JP2000075799A - Display device, electronic equipment, and manufacture of light guide plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display device employing a new layout of a light source in place of the backlight type, electronic equipment, and a method for manufacturing a light guide plate suited for constructing the display device. SOLUTION: In this display device, an upper polarization separator 20, a liquid-crystal panel 10, and a lower polarization separator 50 are arranged in that order, and a light guide plate 130 for guiding light from a LED 120 is placed between the upper polarization separator 20 and the liquid-crystal panel 10. The light guide plate 130 is a resin molding and has no optical anisotropy since it is molded to have round corners. By placing the light guide plate 130 between the first polarization separation means 20 and the second polarization separation means 50, light from the light source 120 is guided thereto for display. Thus, the light source 120 has the advantage of being high in degree of freedom of design since it does not need to be placed on the lower surface of the display device.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, an electronic apparatus provided with the display device, and a method of manufacturing a light guide plate suitable for constituting the display device.

[0002]

2. Description of the Related Art TN (Twisted Nematic) liquid crystal and STN
(Super-Twisted Nematic) In a liquid crystal panel in which a liquid crystal or the like is sealed between a pair of substrates, the alignment state of the liquid crystal can be controlled for each region depending on whether or not an electric field is applied to the liquid crystal between the substrates. Therefore, this liquid crystal panel is a transmission polarization axis variable element (transmission polarization axis variable means) that can switch between the first state and the second state for each area by changing the transmission polarization axis of incident light. Can be used.
A liquid crystal display device using such a transmission polarization axis variable optical element has a structure in which the transmission polarization axis variable optical element is sandwiched between two polarizing plates. If this liquid crystal display device is configured as a transflective type and a backlight is disposed on the back side, display can be performed by the light of the backlight even in a dark place.

For example, in a transflective liquid crystal display device using a TN liquid crystal panel shown in FIG.
130, a liquid crystal panel 5140, a lower polarizer 5170, a semi-transmissive reflector 5180, and a backlight 5190 are arranged in this order. In FIG. 15, the optical elements are illustrated as being separated from each other so that the nature of light at each position can be easily understood. However, in practice, the optical elements are arranged in close contact with each other.

In this liquid crystal display device, a liquid crystal panel 5
In the no-voltage application region of 140, of the external light 5111 incident on the upper polarizing plate 5130, only the linearly polarized light in the direction parallel to the paper surface is transmitted, and then the transmitted polarization axis is twisted by 90 ° in the liquid crystal panel 5140, The light becomes linearly polarized light perpendicular to the paper surface and passes through the liquid crystal panel 5140. LCD panel 51
The light transmitted through the light-transmitting plate 40 passes through the lower polarizing plate 5170 as linearly polarized light in a direction perpendicular to the plane of the paper, and is transmitted through the semi-transmissive reflecting plate 518.
At 0, a part is reflected, but a part is transmitted. The light reflected by the transflector 5180 is again transmitted to the lower polarizer 5170.
Is transmitted as linearly polarized light perpendicular to the paper surface, and the liquid crystal panel 5
After the transmission polarization axis is twisted by 90 ° at 140, the light exits from the upper polarizing plate 5130 as linearly polarized light parallel to the paper surface.

On the other hand, natural light 5112 emitted from the backlight 5190 is partially reflected by the semi-transmissive reflection plate 5180, but partially transmitted. This transflective plate 5180
After only the linearly polarized light perpendicular to the paper surface of the light transmitted through the lower polarizing plate 5170, the liquid crystal panel 51
At 40, the transmission polarization axis is twisted by 90 °, becomes linearly polarized light parallel to the paper surface, and transmits through the liquid crystal panel 5140.
The light transmitted through the liquid crystal panel 5140 passes through the upper polarizing plate 5130 as linearly polarized light parallel to the plane of the paper and is emitted.

On the other hand, in the voltage application region of the liquid crystal panel 5140, the transmission polarization axis is not twisted, so that the light is not emitted from the upper polarizing plate 5130. Therefore, information can be displayed based on the difference in brightness between the voltage application region and the voltage non-application region of the liquid crystal panel 5140.

[0007] The applicant of the present invention has a backlight 519.
Instead of the lower polarizing plate 5180 on the zero side, a transflective display device using a polarization separator that transmits a linearly polarized light component in a predetermined direction and reflects a linearly polarized light component in a direction perpendicular to the predetermined direction is proposed. And filed a patent application (Japanese Patent Application No. 8-245)
346). A transflective display device using this polarization separator will be described with reference to FIG.

In FIG. 16, reference numeral 5120 denotes a voltage non-application region of the TN liquid crystal panel, and reference numeral 5110 denotes a voltage application region of the TN liquid crystal panel. This liquid crystal display device generally includes an upper polarizer 5130, a voltage application region 5110 of the liquid crystal panel, a voltage non-application region 5120 of the liquid crystal panel, a polarization separator 516.
0, semi-transmissive absorption plate 5180 and backlight 5190
Are stacked in this order.

First, a description will be given of white and black display during reflective display using external light. In the voltage non-applied region 5120 of the liquid crystal panel, of the external light 5601 incident on the upper polarizing plate 5130, only linearly polarized light in a direction parallel to the paper surface is transmitted, and then the transmission polarization axis in the voltage non-applied region 5120 of the liquid crystal panel. Is twisted by 90 °, becomes linearly polarized light perpendicular to the plane of the paper, and passes through the no-voltage application region 5120 of the liquid crystal panel. The light transmitted through the no-voltage application region 5120 of the liquid crystal panel is reflected by the lower polarizing plate 5160 as linearly polarized light perpendicular to the plane of the drawing, and then is applied to the no-voltage application region 51 of the liquid crystal panel.
20. The incident linearly polarized light perpendicular to the paper surface is twisted by 90 ° in the transmission polarization axis in the no-voltage application region 5120 of the liquid crystal panel, becomes a linearly polarized light parallel to the paper surface, and becomes a no-voltage application region 5120 of the liquid crystal panel. After transmitting through the upper polarizing plate 5130, white display is performed.

On the other hand, in the voltage application region 5110 of the liquid crystal panel, the external light 56
03, only the linearly polarized light in the direction parallel to the plane of the paper (the linearly polarized light component directed in the first direction) is transmitted, and then the linearly polarized light in the direction parallel to the plane of the paper is left in the voltage application region 5110 of the liquid crystal panel. To Penetrate. Liquid crystal panel voltage application area 511
The light transmitted through 0 transmits through the lower polarizing plate 5160 as linearly polarized light parallel to the paper surface (linearly polarized light component directed in the second direction), and is then absorbed by the semi-transmissive absorption plate 5180. Therefore, this area performs black display.

On the other hand, the voltage non-application region 512 of the liquid crystal panel
At 0, light 5602 from backlight 5190
Are transmitted through the semi-transmissive absorption plate 5180 and are transmitted through the lower polarizing plate 516.
Incident at 0. Of the light that has entered the lower polarizing plate 5160, only linearly polarized light parallel to the paper surface is the lower polarizing plate 516.
0 is transmitted, and is incident on the no-voltage application region 5120 of the liquid crystal panel. The light incident on the no-voltage application area 5120 of the liquid crystal panel has a transmission polarization axis twisted by 90 ° and is converted into linearly polarized light perpendicular to the paper surface of the liquid crystal panel.
, And cannot pass through the upper polarizing plate 5130. Therefore, the non-voltage application region 512 of the liquid crystal panel
0 performs black display.

On the other hand, in the voltage application region 5110 of the liquid crystal panel, the light 56
In No. 04, after transmitting through the semi-transmissive absorption plate 5180, only linearly polarized light parallel to the paper surface passes through the lower polarizing plate 5160 and enters the liquid crystal panel voltage application region 5110. The light incident on the liquid crystal panel 5120 passes through the liquid crystal panel 5120 as linearly polarized light parallel to the paper surface as it is.
The white light is transmitted through the upper polarizing plate 5130 to perform white display.

[0013]

As described above, in any of the conventional liquid crystal display devices, when display by external light cannot be performed, the backlight 5190 must be disposed at the lowest position. There is a restriction in.

An object of the present invention is to provide a display device adopting a new light source arrangement structure instead of the conventional backlight system arranged on the lower side, an electronic device equipped with this display device,
Another object of the present invention is to provide a method for manufacturing a light guide plate suitable for constituting the display device.

[0015]

In order to solve the above-mentioned problems, according to the present invention, of incident light, a linearly polarized light component passing in a first direction is transmitted, and a linearly polarized light component orthogonal to the first direction is reflected or absorbed. (1) a polarization splitting means, and a transmission polarization axis changing means for changing the transmission polarization axis when the incident linearly polarized light component is transmitted, thereby enabling switching for each region between the first state and the second state; A display device in which, among the incident linearly polarized light components, a second polarized light separating unit that transmits a linearly polarized light component oriented in the second direction and reflects or absorbs a linearly polarized light component orthogonal to the second polarized light component is arranged in this order. A light guide plate made of a substantially rectangular resin molded product that guides light from a light source to the side of the second polarized light separating means is disposed between the polarized light separating means and the second polarized light separating means. , 4 of the light guide plate At least one corner of the corners is characterized in that it comprises a planar shape rounded.

In the present invention, the light from the light source is guided to the light guide plate for display by arranging the light guide plate between the first polarization separation means and the second polarization separation means. Therefore, there is an advantage that the degree of freedom in design is high, for example, the light source does not necessarily need to be arranged on the lower surface side of the display device. In addition, in such a configuration, in both of the display using external light and the display using light from the light source,
The light passes through the light guide plate, which is a resin molded product, until the light is emitted toward the observer. Therefore, according to the present invention, by forming the resin so that the corners where optical anisotropy is likely to occur during resin molding of the light guide plate are rounded, stress is concentrated on this portion at the time of resin molding and the light guide plate is formed. Optical anisotropy is prevented from occurring. Therefore, even in a display device using a light guide plate manufactured by resin molding, there is no optical anisotropy, so there is no color unevenness, and there is no useless light absorption due to the light guide plate, so that bright display and color High-quality display with no luminance difference between the two.

In the present invention, for example, at least two adjacent corners of the four corners of the light guide plate have a rounded planar shape.

Here, as the second polarization splitting means, a means for transmitting a linearly polarized light component directed in the second direction among incident linearly polarized light components and reflecting a linearly polarized light component orthogonal thereto is used. it can.

In the present invention, a liquid crystal panel in which liquid crystal is sealed between a pair of substrates can be used as the transmission polarization axis changing means.

The display device having such a configuration can be mounted on an electronic device such as a mobile phone.

According to the present invention, in the method for manufacturing a light guide plate used for a display device having such a configuration, the resin injection gate is opposed to the inside of a mold having a substantially rectangular planar shape into which resin is injected from the resin injection gate. The method is characterized in that a substantially rectangular light guide plate is manufactured by resin molding using a mold having a planar shape with rounded corners on the inner peripheral surface of the mold.

Here, it is preferable that after the resin is injected from the resin injection gate into the mold, pressure is applied to the resin in the mold.

[0023]

Embodiments of the present invention will be described with reference to the drawings.

[First Embodiment] FIG. 1 is a schematic cross-sectional view for explaining a liquid crystal display device to which the present invention is applied and a mobile phone (electronic device) equipped with this liquid crystal display, and FIG.
FIG. 2 is a schematic cross-sectional view for explaining main parts of the liquid crystal display device shown in FIG.

As shown in FIGS. 1 and 2, in the mobile phone 2 of the present embodiment, the liquid crystal display device 1 is formed inside a mobile phone main body case 4 having a transparent cover 3 and the display on the liquid crystal display device 1 is performed. The contents can be observed from outside via the transparent cover 3.

As shown in FIG. 2, the liquid crystal display device 1 uses a liquid crystal panel 10 having a TN type or STN type liquid crystal as a transmission polarization axis variable optical element. A retardation film 30 is disposed on the upper surface of the liquid crystal panel 10, and a diffusion plate 40, a lower polarization separator 50 (second polarization separator), and a color filter 6 are disposed below the liquid crystal panel 10.
0, PET (polyethylene terephthalate) film 7
0, and an aluminum vapor-deposited film 80 (reflecting means) formed on the back side of the PET film 70 are arranged in this order.

In the liquid crystal panel 10, a TN type or STN type liquid crystal 14 is sealed in a cell constituted by two glass substrates 11, 12 and a sealing member 13.

The mobile phone body case 4 includes a PCB board 90
(Printed wiring board) is attached. This PC
On a B substrate 90, an aluminum vapor-deposited film 80, a PET film 70, a color filter 60, a lower polarization separator 5
0, a diffusion plate 40, a liquid crystal panel 10, and a retardation film 30. A plurality of LEs are provided on both sides of the PCB board 90 corresponding to both sides of this structure.
D120 (light source) are arranged in two rows on both sides, and each LED 12
0 is arranged to emit light upward.

Panel fixing frames 11 are provided on both sides of the above-mentioned structure.
The panel fixing frame 110 positions and fixes components such as the liquid crystal panel 10 in the left-right direction. Here, the panel fixing frames 110 are formed from a material having a light transmitting property, and the lower end of each panel fixing frame 110 is a portion for introducing light emitted from the LED 120. These panel fixing frames 1
Reference numeral 10 extends upward along the side surface of the structure such as the liquid crystal panel 10, and the upper end thereof is bent on the retardation film 30 toward the inside of the retardation film 30. A space between the lower surface of the upper end of each panel fixing frame 110 and the retardation film 30 is fixed with a double-sided tape 112.

An upper polarized light separator 20 (first polarized light separating means) is disposed above the upper end of the panel fixing frame 110, and the upper surface of the upper end of the panel fixing frame 110 and the upper polarized light separator 20. Are fixed with a double-sided tape 111.

The retardation film 30 is used as an optically anisotropic body for color compensation, and has a function of compensating coloring generated in the liquid crystal 14 such as STN. Further, the aluminum vapor-deposited film 80 provided on the back surface side of the PET film 70 functions as a reflection unit, and has a function of brightening a color display by the color filter 60.

The upper polarization separator 20 and the lower polarization separator 50
Between the retardation film 30 and the upper polarization separator 2
The light guide plate 130 is disposed between the light guide plate 130 and the light guide plate 130. Both the panel fixing frame 110 and the light guide plate 130 are made of optically isotropic polycarbonate resin or acrylic resin. Therefore, the light emitted from the LED 120 is transmitted to the upper polarization separator 2 by the panel fixing frame 110.
After the light is guided to a position between 0 and the retardation film 30, the light is introduced into the light guide plate 130 from the tip of the upper end of the panel fixing frame 110, and is emitted toward the retardation film 30. The light guide plate 130 transmits light from the upper polarization separator 20 to the retardation film 30 and transmits light from the retardation film 30 to the upper polarization separator 20.

Referring to FIG. 3, liquid crystal display device 1 of the present embodiment
Polarization separator 20 and lower polarization separator 50 used for
Will be described.

The lower polarization splitter 50 has two different layers 5
1 (A layer) and 52 (B layer) have a structure in which a plurality of layers are alternately laminated. Refractive index of the A layer 51 in the X direction (nAX)
Is different from the refractive index (nAY) in the Y direction orthogonal to the X direction. The refractive index (nBX) in the X direction and the refractive index (nBY) in the Y direction of the B layer 52 are equal. The refractive index (nAY) of the A layer 51 in the Y direction is equal to the refractive index (nBY) of the B layer 51 in the Y direction.

Therefore, the upper surface 5 of the lower polarization splitter 50
The linearly polarized light having the transmission polarization axis in the Y direction among the light incident on the lower polarization splitter 50 from the direction perpendicular to 5 is transmitted through the lower light splitter 50 and transmitted through the lower surface 56 in the Y direction. Emitted as linearly polarized light having an axis. Conversely, of the light incident on the lower polarization separator 50 from a direction perpendicular to the lower surface 56 of the lower polarization separator 50, the linearly polarized light having the transmission polarization axis in the Y direction is the lower polarization separator 50. Through,
The light is emitted from the upper surface 56 as linearly polarized light having a transmission polarization axis in the Y direction.

On the other hand, the thickness of the A layer 51 in the Z direction is t
When the thickness of the A and B layers 52 in the Z direction is tB and the wavelength of the incident light is λ, tA · nAX + tB · nBX = λ / 2. The linearly polarized light having the transmission polarization axis in the X direction among the lights of the wavelength λ incident on the lower polarization separator 50 from the direction perpendicular to the upper surface 55 of the polarization separator 50 is converted by the lower polarization separator 50 into X-rays. It is reflected as linearly polarized light with a directional transmission polarization axis. Also,
Linearly polarized light having a transmission polarization axis in the X direction out of the light of wavelength λ incident on the lower polarization separator 50 from a direction perpendicular to the lower surface 56 of the lower polarization separator 50 is the lower polarization separator 5.
By 0, the light is reflected as linearly polarized light having a transmission polarization axis in the X direction.

The thickness t of the A layer 51 in the Z direction
By varying the thickness tB of the A and B layers 52 in the Z direction so that the above equation (1) is satisfied over the entire wavelength range of visible light, the X direction can be applied not only to a single color but also to all white light. Is reflected as linearly polarized light having a transmission polarization axis in the X direction, and linearly polarized light having a transmission polarization axis in the Y direction is transmitted as linearly polarized light having a transmission polarization axis in the Y direction. Is obtained.

In the above description, the lower polarization separator 50 has been described as an example, but the upper polarization separator 20 may have the same structure.

Such a polarized light separator is disclosed as a reflective polarizer in International Publication WO95 / 17692, and the present embodiment also uses the polarized light separator disclosed in this publication.

Referring to FIGS. 4 and 5A, the configuration of the light guide plate 130 used in the liquid crystal display device 1 according to the present embodiment will be described. FIG. 4 and FIG. 5A are a schematic sectional view and a schematic perspective view of the light guide plate, respectively.

In FIG. 4, the light guide plate 130 has a single surface (an emission surface) of a flat plate 131 made of a transparent substantially rectangular resin molded product.
134 has a number of projections 132. Each projection 132
Are cylindrical in shape, and are composed of a bottom surface 135 substantially parallel to the emission surface 134 and a side surface 136 substantially perpendicular to the emission surface 134. The light guide plate 130 is formed of a resin material having a refractive index of about 1.4 or more. The luminous flux emitted from the LED 120 is, as schematically shown by light rays 122 and 123, a side end face 137.
, The light is repeatedly total-reflected in the light guide plate 130, and is emitted only from the side surface 136 of the projection 132. Therefore, the illuminated body 150 can be effectively illuminated.
In this manner, the light guide plate 130 efficiently emits the light incident on the side end surface 137 from the emission surface 134 side, transmits the light incident from the upper surface 133 from the lower surface 134 side, and From the upper surface 133
From the side.

As a transparent material for forming the light guide plate 130, a transparent resin such as an acrylic resin, a polycarbonate resin, and an amorphous polyolefin resin is used. In the present embodiment, an optically isotropic polycarbonate resin is used. I have. The thickness of the light guide plate 130 is 0.2 mm to 2 mm, preferably 0.4 mm to 0.8 mm. The size of the projection 132 is such that the wavelength of visible light is about 380 nm to 700 n.
Since it is about m, it is necessary to be about 5 μm or more so that the influence of diffraction does not occur. In addition, it is desirable that the projection 132 is about 300 μm or less so that the projection 132 is not so noticeable to the naked eye. Further, in consideration of manufacturing convenience, the size of the projection 132 is desirably approximately 10 μm or more and 100 μm or less. In addition, the ratio of the height to the width of the protrusion 132 (the diameter in the case of a substantially cylindrical shape) may be 1 to 1 or less from the viewpoint that the light ray in the light guide plate 130 has an elevation angle of 45 degrees or less in the plane direction. 90% of rays below 20 degrees
Because of the above, sufficient performance is exhibited up to about 1: 2. Therefore, in this embodiment, the diameter of the projection 132 is set to 20 μm.
m, the height was 15 μm, and the pitch was 20 μm.

Further, in this embodiment, as shown in FIG. 5A, the light guide plate 130 has a substantially rectangular planar shape as a whole, but has four corners 136A, 136B, 136.
C, 136D, two adjacent corners 136C, 1
About 36D, it is rounded with a diameter of 0.5 mm to 2.0 mm, preferably 1.0 mm to 1.5 mm,
These corners 136C and 136D have an arc-shaped planar shape.

Therefore, when the light guide plate 130 shown in FIG. 5A is used, for example, as shown in FIG.
A panel fixing frame 110 in which two of the four inner corners have a rounded planar shape is used, and the light guide plate 130 is in close contact with the inner peripheral surface of the panel fixing frame 110.
Is arranged. A plurality of LEDs 120 are arranged at the lower end of the panel fixing frame 110 along the side of the light guide plate 130.

In forming the light guide plate 130 having such a configuration by resin molding, in this embodiment, a light guide plate molding die 230 shown in FIG. 7 is used. This mold 120
In the inside 232 of the female mold 232 having a substantially rectangular planar shape into which resin is injected from the resin injection gate 231, two corners 236C and 236D of the female inner peripheral surface 233 facing the resin injection gate 231 are rounded. It has a frustrated planar shape. Therefore, when the resin injection gate 231 is injected into the gap formed between the female die 232 and the male die 256 after being combined, the resin injection gate
1, two corners 236C of the female inner peripheral surface 233 facing
Since 236D is rounded, these corners 236D
C and 236D also allow the resin to flow smoothly.
Therefore, inside the mold 230, the corners 236C, 2
Since stress concentration does not occur in the resin even in the portion corresponding to 36D, even in the light guide plate 130 manufactured by the resin molding method, the light guide plate 130 does not have optical anisotropy. Therefore, in the light guide plate 130, even if the transmitted polarization axis of the light transmitted through the light guide plate 130 is a linearly polarized light component in any direction, the light is transmitted equally.

In this embodiment, in order to eliminate the optical anisotropy of the light guide plate 130, after the resin has been injected into the mold 230, a higher pressure is applied from the resin injection gate 231 to the inside of the mold. By performing a step of applying a high pressure to the resin 232 or a step of pressing the male mold 256 against the female mold 232, a uniform force is newly applied to the entire resin filled in the mold 230. Therefore, even from this point, the manufactured light guide plate 130 has no optical anisotropy, and evenly transmits a linearly polarized light component whose transmission polarization axis is oriented in any direction.

In the light guide plate 130 shown in FIG. 5A, four corners 136A, 136B, 136C, 136 are provided.
D, two adjacent corners 136C and 136D are rounded, but as shown in FIG.
All four corners 136A, 136B, 136C, 136D may be rounded. When such a light guide plate 130 is used, for example, as shown in FIG. 6B, a panel fixing frame 110 having a planar shape in which all four inner corners are rounded is used. Fixed frame 110
The light guide plate 130 is disposed in close contact with the inner peripheral surface of the light guide plate 130.
The light guide plate 1 is provided at the lower end of the panel fixing frame 110.
A plurality of LEDs 120 are arranged along 30 sides.

Further, in the structure of the mold, if there is only one corner on the inner peripheral surface of the mold facing the resin injection gate, the one corner may be rounded.

The operation of the liquid crystal display device 1 according to the present embodiment will be described with reference to FIGS. In the present embodiment, an STN liquid crystal or the like is used as the liquid crystal 14. However, for the sake of simplicity, a case where a TN liquid crystal is used as the liquid crystal 14 will be described as an example.

FIGS. 8 and 9 show a voltage application region 210 and a voltage non-application region 220 in the liquid crystal panel, respectively.
FIG. 3 is an explanatory view showing a state when external light 215 and 225 are incident on the light, and light 211 and 212 from the LED 120.
FIG. 3 is an explanatory diagram showing a state where light is incident on a voltage application region 210 and a voltage non-application region 220 of the liquid crystal panel. In FIGS. 8 and 9, the optical elements are illustrated as being separated from each other so that the nature of light at each position can be easily understood. However, in actuality, the optical elements are arranged in close contact with each other. Is done.

In FIG. 8, in the voltage non-applied area 220 of the liquid crystal panel 10, of the external light 225 incident on the upper polarized light separator 20 (first polarized light separating means), linearly polarized light (in the direction parallel to the plane of the drawing) After transmitting only the linearly polarized light component directed in the first direction), the light passes through the light guide plate 130 and passes through the liquid crystal panel 10.
To the no-voltage application region 220. This liquid crystal panel 1
The linearly polarized light incident on the zero voltage application region 220 parallel to the paper surface is twisted by 90 ° in the transmission polarization axis, becomes a linear polarization light perpendicular to the paper surface, and becomes a non-voltage application region 2 of the liquid crystal panel 10.
20 is transmitted. No-voltage application area 22 of liquid crystal panel 10
The linearly polarized light (linearly polarized light component directed in a direction orthogonal to the second direction) perpendicular to the paper surface that has passed through the zero-polarized light is transmitted through the diffusion plate 40, and then the lower polarized light separator 50 (second polarized light separating means) Reflected by The linearly polarized light perpendicular to the paper surface reflected by the lower polarization separator 50 again enters the voltage non-applying area 220 of the liquid crystal panel 10. The linearly polarized light that is perpendicular to the plane of the paper and is incident on the non-voltage applied area 220 of the liquid crystal panel 10 has a transmission polarization axis twisted by 90 ° and becomes a linearly polarized light parallel to the plane of the paper. After passing through 220, the light passes through the light guide plate 130 and the upper polarization separator 20 and is emitted as white light 226.

On the other hand, in the voltage application area 210 of the liquid crystal panel 10, the external light 2
15, only the linearly polarized light in the direction parallel to the paper surface (the linearly polarized light component oriented in the first direction) is transmitted,
0, and after that, the light passes through the voltage application region 210 of the liquid crystal panel 10 as linearly polarized light in a direction parallel to the paper surface. The light transmitted through the voltage application region 210 of the liquid crystal panel 10 is transmitted through the diffusion plate 40, and then is converted into linearly polarized light in a direction parallel to the plane of the drawing (linearly polarized light component directed in the second direction) by the lower polarization separator 50. To Penetrate. A part of the linearly polarized light parallel to the sheet of the paper transmitted through the lower polarization separator 50 is reflected by the color filter 60 and a part is transmitted through the color filter 60. The light transmitted through the color filter 60 transmits through the PET film 70 and is reflected by the aluminum vapor-deposited film 80 formed on the back surface thereof.
0, after passing through the color filter 60, the lower polarization separator 50, and the diffusion plate 40, the voltage application area 21 of the liquid crystal panel 10
However, the light incident here is transmitted as a linearly polarized light parallel to the paper surface through the voltage application region 210 of the liquid crystal panel 10 and then transmitted through the light guide plate 130 and the upper polarization separator 20 to be colored. The emitted light 216 is emitted.

On the other hand, in FIG. 9, light emitted from the LED 120 is transmitted to the panel fixing frame 110 and the light guide plate 130.
Then, the light is emitted to the side of the retardation film 30 (the side of the liquid crystal panel 10). Of the light emitted from this, light 221 incident on the no-voltage application area 220 of the liquid crystal panel 10
Is transmitted through the no-voltage application region 220 of the liquid crystal panel 10 with the transmission polarization axis of the linearly polarized light component in each direction twisted by 90 °. The light transmitted through the no-voltage application area 220 of the liquid crystal panel 10 transmits through the diffusion plate 40, and then the linearly polarized light perpendicular to the paper is reflected by the lower polarization separator 50. The linearly polarized light perpendicular to the paper surface reflected by the lower polarization separator 50 has a transmission polarization axis twisted by 90 ° in the no-voltage application region 220 of the liquid crystal panel 10 to become a linearly polarized light parallel to the paper surface. After passing through the no-voltage application area 220 of the panel 10, the light passes through the light guide plate 130 and the upper polarization separator 20 and is emitted as white light 222.

The linearly polarized light parallel to the plane of the paper transmitted through the lower polarization separator 50 is partially reflected by the color filter 60 and partially transmitted through the color filter 60. The light transmitted through the color filter 60 is transmitted through the PET film 70 and is reflected by the aluminum vapor-deposited film 80 formed on the back surface of the PET film 70. The light reflected by the aluminum vapor-deposited film 80 is again transmitted to the PET film 7.
After passing through the color filter 60, the lower polarization separator 50, and the diffusion plate 40, the light enters the voltage non-applied region 220 of the liquid crystal panel 10 as linearly polarized light parallel to the plane of the drawing. Then, the linearly polarized light incident on the voltage non-applied region 220 of the liquid crystal panel 10 and parallel to the plane of the paper has a transmission polarization axis twisted by 90 ° and is linearly polarized light perpendicular to the plane of the paper (in the direction orthogonal to the first direction). After being transmitted as a linearly polarized light component through the no-voltage application area 220 of the liquid crystal panel 10 and the light guide plate 130, the light is reflected by the upper polarized light separator 20 and is not emitted from the upper polarized light separator 20.

On the other hand, of the light of the LED 120 emitted to the phase difference film 30 side (the liquid crystal panel 10 side) through the panel fixing frame 110 and the light guide plate 130,
Light 21 incident on voltage application region 210 of liquid crystal panel 10
1 is a voltage application region 210 of the liquid crystal panel 10 as it is.
Through. The light transmitted through the voltage application region 210 of the liquid crystal panel 10 is transmitted through the diffusion plate 40, and then linearly polarized light perpendicular to the paper is reflected by the lower polarization separator 50. The linearly polarized light perpendicular to the paper surface reflected by the lower polarization splitter 50 is applied to the voltage applied region 2 of the liquid crystal panel 10 while the voltage applied region 210 of the liquid crystal panel 10 remains linearly polarized light perpendicular to the paper surface.
Since the light passes through the light guide plate 10 and the light guide plate 130, the light is reflected by the upper polarized light separator 20 and is not emitted from the upper polarized light separator 20.

On the other hand, the linearly polarized light parallel to the plane of the paper transmitted through the lower polarization separator 50 is partially reflected by the color filter 60 and partially transmitted through the color filter 60. The light transmitted through the color filter 60 is transmitted through the PET film 70 and is reflected by the aluminum vapor-deposited film 80 formed on the back surface of the PET film 70. The light reflected by the aluminum vapor-deposited film 80 is again transmitted to the PET film 7.
After passing through the color filter 60, the lower polarization separator 50, and the diffusion plate 40, the light enters the voltage application region 210 of the liquid crystal panel 10 as linearly polarized light parallel to the paper surface. Then, the linearly polarized light parallel to the paper surface incident on the voltage application region 210 of the liquid crystal panel 10 passes through the voltage application region 210 of the liquid crystal panel 10 as linearly polarized light parallel to the paper surface as it is, and then the light guide plate 130 and the upper side. The light passes through the polarized light separator 20 as colored light 212 and is emitted.

The lower polarization separator 50 and the liquid crystal panel 1
Since the diffusion layer 40 is disposed between the upper and lower parts, the light emitted from the upper polarization separator 20 is soft light.

As described above, in the liquid crystal display device 1 of the present embodiment, when displaying is performed using external light,
In any case of performing display using light from 0, light is transmitted through the light guide plate 130 until the light is emitted from the upper polarization separator 20 to the observer side. Therefore, as shown in FIG. 5C, the four corners 136A, 136
B, 136C, and 136D have a square shape.
When resin is molded, the resin injection gate 2 is formed at the time of resin molding.
31 (see FIG. 7), stress concentration occurs in the resin near the corner corresponding to the part facing the corner 31 (see FIG. 7).
The light guide plate 130 having optical anisotropy is manufactured near 136D, and light to be emitted from the upper polarization separator 20 may be absorbed by the light guide plate 130. However, in the present embodiment, as described with reference to FIG. 5A, the corners 136C and 136D in which the optical anisotropy is likely to be generated during the resin molding of the light guide plate 130 are formed by rounding the resin. This prevents stress from concentrating on this portion during resin molding. Therefore, since the light guide plate 130 used in the liquid crystal display device 1 of the present embodiment does not have optical anisotropy, there is no color unevenness, the entire display is bright, and high-quality display with no color luminance difference is performed. Can be.

In this embodiment, since a polycarbonate resin molded product having high environmental resistance is used as the light guide plate 130, optical anisotropy due to stress at the time of resin molding is easily generated. Since the problem of optical anisotropy can be solved according to this embodiment, the liquid crystal display device 1 with high display quality and high reliability can be realized.

Further, in the liquid crystal display device 1 of the present embodiment, the upper polarization splitter 20 and the liquid crystal panel 1 are formed by the light guide plate 130.
By introducing the light from the LED 120 between 0 and 0 and utilizing the transmission and reflection of the lower polarization separator 50, the liquid crystal can be used for both display using external light and display using light from the LED 120. Since bright colored light is emitted from the upper polarization separator 20 from the voltage application region 210 of the panel 10, the display by the external light and the LED 120
There is also an advantage that so-called positive / negative inversion does not occur between the display and the display by the light from the light source.

The non-voltage application area 2 of the liquid crystal panel 10
The light 222 and 225 incident on the lower polarization separator 5
Since it is reflected at 0 and emitted as 222 and 225,
A bright display is obtained. Moreover, since the diffusion layer 40 is disposed between the lower polarization separator 50 and the TN liquid crystal 14,
The reflected light from the lower polarization splitter 50 has an advantage of performing soft and high-quality display.

Since the aluminum vapor-deposited film 80 functioning as a reflection plate is provided, the color light 212 or 216 colored by the color filter 60 becomes bright.

The transmission axis of the lower polarization splitter 50 is set to 90
It is also possible to reverse the display mode performed in the voltage application region and the voltage non-application region by rotating by °. That is, display by external light,
In both of the display using light from the light source such as the LED 120 and the like, a negative type display may be performed.

Further, in the voltage non-applying section 220, the light reflected by the lower polarization separator 50 is scattered by the diffusion layer 40 to become white light 222, 226. The light transmitted through the polarization separator 50 is colored by the color filter 60 to become color emission lights 212 and 216, and a color display is obtained on a white background. Are absorbed, and black display can be performed on a white background.

[Second Embodiment] From the viewpoint of preventing the display quality from deteriorating due to the optical anisotropy of the light guide plate 130, a linearly polarized light component oriented in a predetermined direction is transmitted, and is orthogonal to the component. The present invention is also effective for a liquid crystal display device using a polarizing plate having a polarization characteristic of absorbing a linearly polarized light component.

An embodiment in which the present invention is applied to a liquid crystal display device using such a polarizing plate will be described with reference to FIGS. In FIGS. 10 and 11, the optical elements are illustrated as being separated from each other so that the properties of light at the respective positions can be easily understood. Is done.

As shown in FIGS. 10 and 11, in the liquid crystal display device 1 of the present embodiment, the upper polarizing plate 20C (first polarization separating means) and the TN type or S type as the variable transmission polarization axis optical element are used.
Liquid crystal panel 10 having TN type liquid crystal, lower polarizing plate 5
An 0C (second polarized light separating means), a PET (polyethylene terephthalate) film 70, and an aluminum deposited film 80 (reflecting means) formed on the PET film 75 are arranged in this order.

Also, as described with reference to FIGS. 1 and 2, also in the liquid crystal display device 1 of the present embodiment, the panel fixing frame 110 is raised upward along the side surface of the structure such as the liquid crystal panel 10. A light guide plate 130 is disposed between the upper polarizer 20 </ b> C and the liquid crystal panel 10. Therefore, also in the present embodiment, the light emitted from the LED 120 can be guided to the light guide plate 130 via the panel fixing frame 110 and further emitted toward the liquid crystal panel 10.

Also in this embodiment, the light guide plate 130 is the same as that shown in FIG.
As described with reference to FIG. 5A and FIG. 5A, one surface (emission surface) of the flat plate 131 made of a transparent substantially rectangular resin molded product.
134 is provided with a number of projections 132,
Out of the liquid crystal panel 10. The light guide plate 130 is a resin molded product made of an acrylic resin, a polycarbonate resin, an amorphous polyolefin resin, or the like. Here, the light guide plate 130 has a substantially rectangular planar shape as a whole.
Of the 6A, 136B, 136C, and 136D, two adjacent corners 136C and 136D are rounded, and these corners 136C and 136D have an arc-shaped planar shape. That is, as described with reference to FIG. 7, in the mold 230 for forming the light guide plate 130 by resin molding, the two corners 236C, 236D of the female inner peripheral surface 233 facing the resin injection gate 231. Is angular, optical anisotropy occurs at portions corresponding to the corners 236C and 236D in the light guide plate 130 shown in FIG. 5C, so that in the present embodiment, the female mold facing the resin injection gate 231 is formed. Two corners 236C, 236 of peripheral surface 233
D is rounded to prevent optical anisotropy from occurring in portions corresponding to the corners 236C and 236D (the corners 136C and 136D of the light guide plate 130). Also in this embodiment, after the resin is injected into the mold 230, a step of applying a higher pressure to the resin in the mold interior 232 with a higher pressure from the resin injection gate 231, or a male By performing a process such as pressing the mold 256, a uniform force is newly applied to the entire resin filled in the mold 230. Therefore, even from this point, the manufactured light guide plate 130 has no optical anisotropy, and evenly transmits a linearly polarized light component whose transmission polarization axis is oriented in any direction.

In this embodiment, as shown in FIG. 5B, four corners 136A, 136B, 136C, 136 are formed.
D may be rounded. Furthermore, in the structure of the mold, the corner of the inner peripheral surface of the mold facing the resin injection gate is 1 mm.
If it is only a location, the one corner may be rounded.

The operation of the liquid crystal display device 1 according to the present embodiment will be described with reference to FIGS. In the present embodiment, an STN liquid crystal or the like is used as the liquid crystal 14. However, for simplicity, a case where a TN liquid crystal is used as the liquid crystal 14 will be described as an example.

FIGS. 10 and 11 show a voltage application region 210 and a voltage non-application region 2 in the liquid crystal panel, respectively.
FIG. 4 is an explanatory view showing a state where external light 215 and 225 are incident on the light 20, and light 211 and light 2 from the LED 120.
FIG. 12 is an explanatory diagram showing a state where the light enters a voltage application region 210 and a voltage non-application region 220 of the liquid crystal panel.

In FIG. 10, in the voltage non-applied area 220 of the liquid crystal panel 10, of the external light 225 incident on the upper polarizing plate 20C, the linearly polarized light in the direction parallel to the paper surface (the linearly polarized light component in the first direction). Only) pass through the upper polarizer 20C and the light guide plate 130, and then enter the voltage non-applying area 220 of the liquid crystal panel 10. The linearly polarized light parallel to the sheet of paper incident on the voltage non-applied area 220 of the liquid crystal panel 10 is twisted by 90 ° in the transmission polarization axis, becomes a linearly polarized light perpendicular to the sheet of paper, and becomes a voltage non-applied area of the liquid crystal panel 10. 220 is transmitted. The linearly polarized light (linearly polarized light component directed in a direction orthogonal to the second direction) perpendicular to the paper surface that has passed through the non-voltage-applied region 220 of the liquid crystal panel 10 is transmitted to the lower polarizing plate 50C.
And is not emitted from the upper polarizing plate 20C.

On the other hand, in the voltage application region 210 of the liquid crystal panel 10, the external light 21
5, after only the linearly polarized light in the direction parallel to the paper surface (the linearly polarized light component directed in the first direction) passes through the upper polarizing plate 20C and the light guide plate 130, remains linearly polarized light in the direction parallel to the paper surface. The light passes through the voltage application region 210 of the liquid crystal panel 10. The light transmitted through the voltage application region 210 of the liquid crystal panel 10 transmits through the lower polarizing plate 50C as linearly polarized light (a linearly polarized light component directed in the second direction) in a direction parallel to the paper surface. The linearly polarized light transmitted through the lower polarizing plate 50C and parallel to the paper surface passes through the PET film 70, is reflected by the aluminum vapor-deposited film 80 formed on the back surface side, and then is again subjected to P
After passing through the ET film 70 and the lower polarizing plate 50C, the light enters the voltage application region 210 of the liquid crystal panel 10.
The light incident here passes through the voltage application region 210 of the liquid crystal panel 10 as it is as linearly polarized light parallel to the paper surface, and then passes through the light guide plate 130 and the upper polarization separator 20,
Is emitted.

On the other hand, in FIG. 11, light emitted from the LED 120 is applied to the panel fixing frame 110 and the light guide plate 13.
The light is emitted to the side of the liquid crystal panel 10 through 0. Of the light emitted from this, the light 221 incident on the no-voltage application area 220 of the liquid crystal panel 10 has the transmission polarization axis of the linearly polarized light component oriented in each direction twisted by 90 °, and 220 is transmitted. Of the light transmitted through the no-voltage application region 220 of the liquid crystal panel 10, only linearly polarized light parallel to the paper surface transmits through the lower polarization separator 50. And
The linearly polarized light that is parallel to the paper and transmitted through the lower polarization separator 50 is transmitted through the PET film 70, and the aluminum vapor-deposited film 80 formed on the back side of the PET film 70.
Reflected by The light reflected by the aluminum deposition film 80 is again transmitted to the PET film 70 and the lower polarization separator 5.
After passing through 0, the light enters the no-voltage application area 220 of the liquid crystal panel 10 as linearly polarized light parallel to the paper surface. And
The linearly polarized light parallel to the sheet of paper incident on the no-voltage application area 220 of the liquid crystal panel 10 has its transmission polarization axis twisted by 90 °,
After being converted into linearly polarized light perpendicular to the paper and passing through the no-voltage application area 220 of the liquid crystal panel 10 and the light guide plate 130, the light is absorbed by the upper polarizer 20C and is not emitted from the upper polarizer 20C.

On the other hand, of the light emitted from the LEDs 120 through the panel fixing frame 110 and the light guide plate 130 toward the liquid crystal panel 10, the natural light 211 incident on the voltage application region 210 of the liquid crystal panel 10 remains unchanged. , Through the voltage application region 210 of the liquid crystal panel 10. Then, of the light transmitted through the voltage application region 210 of the liquid crystal panel 10, only the linearly polarized light parallel to the paper surface is the lower polarization separator 50.
Through. Then, the linearly polarized light parallel to the paper surface that has passed through the lower polarization separator 50 passes through the PET film 70 and is reflected by the aluminum vapor-deposited film 80 formed on the back side of the PET film 70. The light reflected by the aluminum deposition film 80 is again transmitted to the PET film 70.
After passing through the lower polarization separator 50, the voltage application area 210 of the liquid crystal panel 10 is converted into linearly polarized light parallel to the paper surface.
Incident on. Then, the voltage application area 2 of the liquid crystal panel 10
The linearly polarized light parallel to the paper surface incident on 10 is
After passing through the voltage application region 210 of the liquid crystal panel 10, the light passes through the light guide plate 130 and the upper polarizing plate 20C, and is emitted from the upper polarizing plate 20C.

As described above, also in the liquid crystal display device 1 of the present embodiment, when performing display using external light,
In any case of performing display using light from 0, light is transmitted through the light guide plate 130 until the light is emitted from the upper polarization separator 20 to the observer side. Still,
In the present embodiment, as described with reference to FIG. 5A, the resin is formed by rounding the corners 136C and 136D at which optical anisotropy is likely to occur during the resin molding of the light guide plate 130. This prevents stress from being concentrated on this portion during resin molding. Therefore, since the light guide plate 130 used in the liquid crystal display device 1 of the present embodiment has no optical anisotropy,
There is no color unevenness and the entire display is bright.

[Embodiment 3] In Embodiments 1 and 2,
Although the light guide plate is arranged between the first polarization separation means and the transmission polarization axis variable means, the light guide plate 130 may be provided between the first polarization separation means and the second polarization separation means. The second
The light guide plate may be arranged between the polarized light separating means and the transmitted polarization axis changing means. For example, as shown in FIGS. 12 and 13, in the liquid crystal display device described in the first embodiment, light guide plate 130 may be arranged between lower polarization splitter 50 and liquid crystal panel 10.

FIGS. 12 and 13 are an explanatory diagram for explaining a display operation by external light and an explanatory diagram for explaining a display operation by a light source in a liquid crystal display device to which the present invention is applied. FIG. 12 and FIG.
However, although the optical elements are shown as being separated from each other so that the properties of light at the respective positions can be easily understood, the optical elements are actually arranged in close contact with each other.

As shown in FIGS. 12 and 13, in the present embodiment, the upper polarized light separator 20 (first polarized light separating means), the liquid crystal panel 10 (transmitted polarization axis variable means), the light guide plate 130,
Diffusion plate 40, lower polarized light separator 50 (second polarized light separating means), color filter 60, PET (polyethylene terephthalate) film 70, and aluminum vapor-deposited film 80 (reflecting means) formed on the back side of this PET film 70 ) Are arranged in this order. The illustration of the retardation film and the like is omitted.

Also in this embodiment, the lower polarization splitter 50 is
As described with reference to the above, of the incident light of wavelength λ, linearly polarized light having a transmission polarization axis in the X direction is reflected as linearly polarized light having a transmission polarization axis in the X direction, and transmission in the Y direction is performed. Linearly polarized light having a polarization axis is transmitted as linearly polarized light having a transmission polarization axis in the Y direction.

As described with reference to FIG. 4, the light guide plate 130 has a large number of projections 132 on one surface (output surface) 134 of a flat plate 131 made of a transparent substantially rectangular resin molded product. The light flux emitted from the LED 120 (light source) enters the light from the side end surface 137, and then repeats total reflection in the light guide plate 130, and emits only from the side surface 136 of the protrusion 132. The light incident from the lower surface 134 is
From the side. As a transparent material for forming the light guide plate 130, a transparent resin such as an acrylic resin, a polycarbonate resin, and an amorphous polyolefin resin is used. Also in the present embodiment, as shown in FIG. 5A, the light guide plate 130 has a substantially rectangular planar shape as a whole, but two of the four corners 136A, 136B, 136C, and 136D are adjacent to each other. Since the two corners 136C and 136D are rounded, as described in Embodiment 1, the transmitted polarization axis of the light transmitted through the light guide plate 130 is a linearly polarized light component in any direction. Are equally transmitted.

The operation of the liquid crystal display device 1 will be described with reference to FIGS. Also in this embodiment, STN is used as the liquid crystal.
Although a liquid crystal or the like is used, a case in which a TN liquid crystal is used as the liquid crystal will be described here for simplicity.

FIG. 12 shows that the external light 2 is applied to the voltage application area 210 and the voltage non-application area 220 in the liquid crystal panel.
15 and 225 are shown, and FIG. 13 shows a state where light from the LED 120 is incident on the voltage application area 210 and the voltage non-application area 220 of the liquid crystal panel.

In FIG. 12, in the voltage non-applied area 220 of the liquid crystal panel 10, of the external light 225 incident on the upper polarized light separator 20 (first polarized light separating means), a linearly polarized light ( After transmitting only the linearly polarized light component directed in the first direction), the voltage non-applied region 22 of the liquid crystal panel 10
Incident at 0. No-voltage application area 2 of this liquid crystal panel 10
The linearly polarized light parallel to the plane of the light incident on the paper 20 is twisted by 90 ° in the transmission polarization axis, becomes linearly polarized light perpendicular to the plane of the paper, and transmits through the voltage-free area 220 of the liquid crystal panel 10. The linearly polarized light (linearly polarized light component directed in a direction orthogonal to the second direction) perpendicular to the paper surface transmitted through the voltage non-applied region 220 of the liquid crystal panel 10 is transmitted through the light guide plate 130 and the diffusion plate 40 and then to the lower side. The light is reflected by the polarization separator 50 (second polarization separation means). The linearly polarized light perpendicular to the paper surface reflected by the lower polarization splitter 50 is again transmitted to the diffusion plate 40 and the light guide plate 130.
And is incident on the no-voltage application area 220 of the liquid crystal panel 10. The linearly polarized light incident on the voltage non-applied area 220 of the liquid crystal panel 10 and perpendicular to the plane of the paper has a transmission polarization axis of 90.
The liquid crystal panel 10 is twisted, becomes linearly polarized light parallel to the paper surface, transmits through the no-voltage application region 220 of the liquid crystal panel 10, transmits through the upper polarization separator 20, and is emitted as white light 226.

On the other hand, in the voltage application region 210 of the liquid crystal panel 10, the external light 2
15, only the linearly polarized light in the direction parallel to the paper surface (the linearly polarized light component in the first direction) is transmitted, and then the voltage application region 210 of the liquid crystal panel 10 is kept in the linearly polarized light direction in the direction parallel to the paper surface. To Penetrate. Voltage application area 2 of liquid crystal panel 10
The light transmitted through 10 transmits through the light guide plate 130 and the diffusion plate 40, and then transmits through the lower polarization separator 50 as linearly polarized light in a direction parallel to the paper surface (linearly polarized light component directed in the second direction). A part of the linearly polarized light parallel to the sheet of paper transmitted through the lower polarization separator 50 is reflected by the color filter 60,
Part of the light passes through the color filter 60. The light transmitted through the color filter 60 passes through the PET film 70 and is reflected by the aluminum vapor-deposited film 80 formed on the back surface of the PET film 70.
0, lower polarization separator 50, diffusion plate 40 and light guide plate 13
0, the voltage application area 220 of the liquid crystal panel 10
However, the light incident here is transmitted as it is as linearly polarized light parallel to the paper surface, as it is, through the voltage application region 210 of the liquid crystal panel 10, then through the upper polarization separator 20, and as colored light 216. Is emitted.

On the other hand, in FIG. 13, light emitted from LED 120 is applied to panel fixing frame 110 and light guide plate 13.
The light is emitted through the diffusion plate 40 to the side of the diffusion plate 40 (the side opposite to the liquid crystal panel 10). The light emitted from here is the diffuser 4
After passing through 0, linearly polarized light perpendicular to the plane of the paper is reflected by the lower polarization separator 50. The linearly polarized light perpendicular to the paper surface reflected by the lower polarization splitter 50 passes through the diffusion plate 40 and the light guide plate 130 and then enters the voltage non-applied area 220 of the liquid crystal panel 10. And this liquid crystal panel 10
The transmission polarization axis is twisted by 90 ° in the no-voltage application region 220 of FIG.
After passing through the zero voltage application region 220, the light passes through the upper polarization separator 20 and is emitted as white light 222.

The linearly polarized light parallel to the plane of the paper transmitted through the lower polarization separator 50 is partially reflected by the color filter 60 and partially transmitted through the color filter 60. The light transmitted through the color filter 60 is transmitted through the PET film 70 and is reflected by the aluminum vapor-deposited film 80 formed on the back surface of the PET film 70. The light reflected by the aluminum vapor-deposited film 80 is again transmitted to the PET film 7.
0, after passing through the color filter 60, the lower polarization splitter 50, the diffusion plate 40, and the light guide plate 130, as a linearly polarized light parallel to the plane of the drawing, the voltage application region 220 of the liquid crystal panel 10
Incident on. Then, the linearly polarized light incident on the voltage non-applied region 220 of the liquid crystal panel 10 and parallel to the plane of the paper has a transmission polarization axis twisted by 90 ° and is linearly polarized light perpendicular to the plane of the paper (in the direction orthogonal to the first direction). After being transmitted as a linearly polarized light component through the no-voltage application region 220 of the liquid crystal panel 10, it is reflected by the upper polarization separator 20 and is not emitted from the upper polarization separator 20.

On the other hand, through the panel fixing frame 110 and the light guide plate 130, the side of the diffusion plate 40 (the liquid crystal panel 10
Out of the light emitted from the LED 120 out of the LED 120, the light 211 incident on the voltage application region 210 of the liquid crystal panel 10.
After the light passes through the diffusion plate 40, linearly polarized light perpendicular to the paper surface is reflected by the lower polarization splitter 50. The linearly polarized light perpendicular to the paper surface reflected by the lower polarization splitter 50 passes through the diffusion plate 40 and the light guide plate 130, and then passes through the liquid crystal panel 1
Since the zero voltage application region 210 is transmitted through the voltage application region 210 of the liquid crystal panel 10 while being linearly polarized light perpendicular to the plane of the paper, the light is reflected by the upper polarization separator 20 and becomes the upper polarization separator 2.
No light is emitted from 0.

On the other hand, the linearly polarized light parallel to the plane of the paper transmitted through the lower polarization separator 50 is partially reflected by the color filter 60 and partially transmitted through the color filter 60. The light transmitted through the color filter 60 is transmitted through the PET film 70 and is reflected by the aluminum vapor-deposited film 80 formed on the back surface of the PET film 70. The light reflected by the aluminum vapor-deposited film 80 is again transmitted to the PET film 7.
After passing through the color filter 60, the lower polarization separator 50, the diffusion plate 40, and the light guide plate 130, the light enters the voltage application region 210 of the liquid crystal panel 10 as linearly polarized light parallel to the plane of the drawing. Then, the voltage application area 21 of the liquid crystal panel 10
The linearly polarized light parallel to the plane of the light incident on 0 is transmitted as it is as a linearly polarized light parallel to the plane of the paper through the voltage application region 210 of the liquid crystal panel 10 and then transmitted as colored light 212 through the upper polarization separator 20. Is emitted.

As described above, also in the liquid crystal display device 1 of the present embodiment, when performing display using external light,
In any case of performing display using light from 0, light is transmitted through the light guide plate 130 until the light is emitted from the upper polarization separator 20 to the observer side. Still,
In the present embodiment, as described with reference to FIGS. 5A and 5B, the resin is formed by rounding the corners where optical anisotropy is likely to occur when forming the light guide plate 130 with resin. This prevents stress from concentrating on this portion during resin molding. Therefore, since the light guide plate 130 used in the liquid crystal display device 1 of the present embodiment does not have optical anisotropy, there is no color unevenness, the entire display is bright, and high-quality display with no color luminance difference is performed. Can be.

In the present embodiment, since a polycarbonate resin molded product having high environmental resistance is used as the light guide plate 130, optical anisotropy due to stress during resin molding is likely to occur. Since the problem of optical anisotropy can be solved according to this embodiment, the liquid crystal display device 1 with high display quality and high reliability can be realized.

Further, in the liquid crystal display device 1 of the present embodiment, the upper polarization separator 20 and the liquid crystal panel 1 are formed by the light guide plate 130.
By introducing the light from the LED 120 between 0 and 0 and utilizing the transmission and reflection of the lower polarization separator 50, the liquid crystal can be used for both display using external light and display using light from the LED 120. Since bright colored light is emitted from the upper polarization separator 20 from the voltage application region 210 of the panel 10, the display by the external light and the LED 120
There is an advantage similar to that of the first embodiment, such as an advantage that so-called positive / negative inversion does not occur between the display and the display by the light from the light source.

[Other Embodiments] In each of the above embodiments, a TN liquid crystal has been described as an example. However, instead of a TN liquid crystal, an STN liquid crystal or an ECB (Electrical) is used.
The basic operation principle is the same even if another transmission polarization axis such as a liquid crystal (liquid crystal) is used by a voltage or the like.

Further, as a structure for emitting light from the light guide plate 130, in any of the above-described embodiments, a structure in which a columnar projection 132 is formed is used. However, as shown in FIG. Light guide plate 130 having a conical concave portion as shown in FIG. 14 (B), and light guide plate 130 having a substantially hemispherical concave portion as shown in FIG. 14 (C). 130 and a light guide plate 130 having a columnar recess as shown in FIG. 14D can also be used.

Further, the density distribution of the irregularities may be changed in the plane so that the surface luminance of the light guide plate 130 becomes uniform.

Further, in the above embodiment, a portable telephone has been described as an example of an electronic device provided with the liquid crystal display device according to the present invention. However, the present invention is not limited to this, and may be applied to a liquid crystal display device mounted on various electronic devices. The present invention may also be applied.

[0098]

As described above, in the display device according to the present invention, the light guide plate is disposed between the first polarization splitting means and the second polarization splitting means, so that the light from the light source is placed here. And display. Therefore, there is an advantage that the degree of freedom in design is high, for example, it is not necessary to arrange the light source on the lower surface side of the display device. In addition, when performing display using external light, or when performing display using light from a light source introduced by a light guide plate made of a resin molded product disposed between two polarization separating units. In this case, the light passes through the light guide plate until the light is emitted toward the observer. Nevertheless, according to the present invention, the resin is formed such that the corners where optical anisotropy is likely to occur during resin molding of the light guide plate are rounded. Optical anisotropy is prevented from occurring. Therefore, even in a display device using a light guide plate manufactured by resin molding, since there is no optical anisotropy, there is no color unevenness, and there is no useless light absorption caused by the light guide plate, so that bright display and color display are achieved. High-quality display with no difference in luminance can be realized.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view for explaining a liquid crystal display device for a mobile phone according to a first embodiment of the present invention.

FIG. 2 is an enlarged schematic cross-sectional view of the liquid crystal display device shown in FIG.

FIG. 3 is a schematic perspective view illustrating a polarization separator used in the liquid crystal display device shown in FIG.

FIG. 4 is a schematic cross-sectional view for explaining a light guide plate used in the liquid crystal display device shown in FIG.

5A and 5B are perspective views of a light guide plate used in the liquid crystal display device according to the present invention, and FIG.
It is a perspective view of the light guide plate concerning a comparative example.

6 (A) and 6 (B) are each a light guide plate, a panel fixing frame, and an LE used in the liquid crystal display device according to the present invention.
It is explanatory drawing which shows the planar positional relationship of D.

FIG. 7A is an exploded perspective view of a mold for explaining a method of manufacturing the light guide plate in FIG.

FIG. 8 is an explanatory diagram for explaining a display operation by external light in the liquid crystal display device shown in FIG.

FIG. 9 is an explanatory diagram for explaining a display operation by a light source in the liquid crystal display device shown in FIG.

FIG. 10 is an explanatory diagram for explaining a display operation by external light in the liquid crystal display device according to the second embodiment of the present invention.

FIG. 11 is an explanatory diagram for explaining a display operation by a light source in the liquid crystal display device according to the second embodiment of the present invention.

FIG. 12 is an explanatory diagram for explaining a display operation by external light in the liquid crystal display device according to Embodiment 3 of the present invention.

FIG. 13 is an explanatory diagram for explaining a display operation by a light source in the liquid crystal display device according to Embodiment 3 of the present invention.

14 (A) to (D) are explanatory diagrams each showing a modification of the light guide plate shown in FIG. 5;

FIG. 15 is an explanatory diagram for explaining a display operation in a conventional liquid crystal display device.

FIG. 16 is an explanatory diagram for explaining a display operation in the liquid crystal display device according to the reference example.

[Explanation of symbols]

Reference Signs List 1 liquid crystal display device 2 mobile phone (electronic device) 3 transparent cover 4 mobile phone main body case 10 liquid crystal cell 14 liquid crystal layer 20 upper polarization separator (first polarization separator) 20C upper polarizer (first polarization separator) REFERENCE SIGNS LIST 30 retardation film 40 diffusion plate 50 lower polarization separator (second polarization separation unit) 50C lower polarization plate (second polarization separator) 60 color filter 70 PET film 80 aluminum evaporated film (reflection unit) 90 PCB Substrate 110 Panel fixing frame 120 LED 130 Light guide plate 136A, 136B, 136C, 136D Corner of light guide plate 230 Mold 233 Female inner peripheral surface 231 Resin injection gate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H091 FA02Z FA08X FA08Z FA11X FA14Z FA23X FA23Y FA23Z FA31Z FA45Z FB02 FB08 FC01 FC02 FC17 FC29 FD01 HA07 HA10 LA11 LA16 5G435 AA02 AA03 AA04 BB12 BB16 CC12 DD13 FF03 FF03 FF03 FF03 GG23 GG26 HH02 HH05 KK07 KK10 LL07

Claims (6)

[Claims] A first polarized light separating means for transmitting a linearly polarized light component in a first direction and reflecting or absorbing a linearly polarized light component orthogonal to the first polarized light component; and transmitting the incident linearly polarized light component. A transmission polarization axis changing unit that enables switching between the first state and the second state for each region by changing a transmission polarization axis at the time; and a linear polarization component of the incident linear polarization component that is oriented in the second direction. And a second polarization separating means for reflecting or absorbing a linearly polarized light component orthogonal to the second polarized light separating means is disposed in this order, between the first polarized light separating means and the second polarized light separating means. A light guide plate made of a substantially rectangular resin molded product for guiding light from a light source toward the second polarization splitting means is arranged, and at least one of four corners of the light guide plate is provided. The part is rounded Display apparatus characterized by comprising a planar shape. 2. The display device according to claim 1, wherein at least two adjacent corners of the four corners of the light guide plate have a rounded planar shape. 3. The display device according to claim 1, wherein the transmission polarization axis changing unit is a liquid crystal panel in which liquid crystal is sealed between a pair of substrates. 4. An electronic apparatus comprising the display device defined in claim 1. 5. A mold having a substantially rectangular planar shape into which a resin is injected from a resin injection gate, wherein a corner of an inner peripheral surface of the mold facing the resin injection gate has a rounded planar shape. A method for manufacturing a light guide plate, wherein a substantially rectangular light guide plate is manufactured by resin molding using a mold. 6. The method for manufacturing a light guide plate according to claim 5, wherein after injecting the resin into the mold from the resin injection gate, a pressure is applied to the resin in the mold. .