JP2010129503A - Lighting system and projector equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system and a projector equipped with the same, readily and reliably increasing the use efficiency of light by considering the flux form of light outgoing from a lamp. <P>SOLUTION: Positions of reflective surfaces 30a, 30b relative to respective light source lamp units 10, 20 are displaced toward the upstream of an optical path beyond second focal points F2a, F2b which are to be references, corresponding to the flux form of the outgoing light IL. Thus, the outgoing lights IL which are synthesized on the reflective surfaces 30a, 30b can be made to reflect in such a state that the outgoing lights IL are adjacent to each other while maintaining original characteristics in an optical design such as setting of reflection angles of first and second reflectors 12, 22 and a synthetic mirror 30. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an illumination device that combines illumination light generated from a plurality of lamps to form illumination light, and a projector including the illumination device.

2. Description of the Related Art A projection-type image display device such as a projector is known that forms a bright image using an illumination device having two light source devices (see, for example, Patent Document 1). When illuminating light beams from two light source devices arranged opposite to each other are reflected in substantially the same direction by a mirror having a V-shaped reflection surface and combined to form illumination light, for example, In each case, an elliptical reflector is used as a condensing optical system, the light emitting point of the light source light is arranged at the first focal point of the reflector, and the V-shaped reflecting surface of the mirror is at the second focal point or in the vicinity thereof. It is arranged. Thereby, the utilization efficiency of light is improved by condensing light on the reflective surface (see the same as above).
Japanese Patent No. 4045692

  In order to improve the light utilization efficiency and the like when two lights are reflected and synthesized in substantially the same direction by using a mirror having a V-shaped reflecting surface as in Patent Document 1 above, It is desirable that the light from the two directions be as close as possible during synthesis. That is, it is desirable that light be incident on the side of the reflecting surface of the mirror that is as close to the V-shaped edge portion (tip portion) as possible, that is, the direction in which the mirror reflects light. However, even if, for example, an elliptical reflector is used as the condensing optical system and the reflecting surface of the mirror is arranged at the second focal point of the reflector, the influence of the shape of the arc tube on the light source side, the spread of the arc position, etc. Thus, the light beam emitted from the lamp does not necessarily converge at one point as ideal at the second focal point. Further, the second focus of the reflector or the like is not necessarily in an optimal state in order that the cross-sectional shapes of the light beams are not necessarily close to each other.

  Therefore, the present invention provides an illuminating device capable of easily and surely improving the light utilization efficiency by taking into consideration the shape of the actual light beam emitted from the lamp, and a projector including such an illuminating device. The purpose is to provide.

  In order to solve the above-described problems, the illumination device according to the present invention condenses the first and second arc tubes that generate light source light and the light source light generated from the first and second arc tubes, respectively. Are disposed between the first and second lamps, and the first and second lamps having first and second reflectors that are spaced apart from each other while being emitted from the first and second lamps. Including a reflecting surface arranged corresponding to the minimum position of the beam size of the emitted light from at least one of the two lamps, and reflecting each emitted light emitted from each of the first and second lamps in the same direction. And a V-shaped combining mirror for combining.

  In the illuminating device, the reflecting surface of the combining mirror is arranged not corresponding to the focal position on the lamp optical system but corresponding to the minimum position of the beam size of the emitted light from at least one of the first and second lamps. . Accordingly, when combining the light to form illumination light, the light can be brought closer to the combined optical axis, so that the light use efficiency can be improved easily and reliably.

  Further, according to a specific aspect of the present invention, the combining mirror is disposed as the above-described reflecting surface corresponding to the minimum position of the beam size of the emitted light from both the first lamp and the second lamp. First and second reflecting surfaces. In this case, in the light synthesis, the light from both the first lamp and the second lamp can be brought close to each other, so that the light use efficiency can be improved easily and reliably.

  According to another aspect of the present invention, the minimum position of the beam size of the emitted light from at least one of the first and second reflectors is such that the reflecting surface of the combining mirror corresponding to the optical axis of the reflector and the reflector At or near the intersection. In this case, the beam size of the emitted light on the reflection surface of the composite mirror can be surely minimized.

  According to another aspect of the present invention, the first and second reflectors are elliptical. Here, an elliptical reflector is obtained by rotating not only a reflector having a part of a spheroidal surface formed by rotating the ellipse as a reflecting surface, but also a free curve corrected for the ellipse around the optical axis. Also included is a reflector having a curved surface as a reflecting surface. In this case, various optical designs can be performed using the axis passing through the first focus and the second focus corresponding to the basic spheroid as the optical axis. It is assumed that the minimum position of the beam size is a position deviated from the second focal point even after correction.

  According to another aspect of the present invention, the minimum position of the beam size of the emitted light from at least one of the first and second reflectors is located upstream of the corresponding second focal point of the reflector. is there. In this case, the minimum position of the beam size of the emitted light is separated from the position of the second focal point of the reflector to the upstream side of the optical path, and the light utilization efficiency can be simplified by performing synthesis by reflecting the corresponding light. It can certainly be improved.

  According to another aspect of the present invention, the minimum position of the beam size of the emitted light from at least one of the first and second reflectors is located on the downstream side of the optical path from the position of the corresponding second focal point of the reflector. is there. In this case, the minimum position of the beam size of the emitted light is separated from the position of the second focal point of the reflector to the downstream side of the optical path, and the light utilization efficiency can be simplified by performing synthesis by reflecting the corresponding light. It can certainly be improved.

  According to another aspect of the present invention, the first and second lamps are high-pressure discharge lamps that are either high-pressure mercury lamps or metal halide lamps. In this case, for example, even if an illumination device is incorporated in a projector or the like, substantially white light source light having a light quantity sufficient for image light formation by the projector can be generated.

  According to another aspect of the present invention, the first lamp and the second lamp are optical systems having the same specification, and are arranged symmetrically with respect to the combining mirror. In this case, the light formed by the synthesis of the light from each lamp is balanced.

  According to another aspect of the present invention, the illumination device further includes a collimating optical system that collimates the synthesized outgoing light on the downstream side of the optical path of the synthesis mirror. In this case, since the light is collimated, the illumination device is suitable for use in, for example, a projector.

  As a specific aspect of the present invention, a projector according to the present invention projects any one of the illumination devices described above, a light modulation device that is illuminated by illumination light from the illumination device, and image light that has passed through the light modulation device. A projection optical system. In this case, by using the illumination device, the projector can project an image whose luminance is improved by improving the light utilization efficiency.

  FIG. 1 is a schematic plan view for explaining an optical system of a projector in which the illumination device according to the first embodiment is incorporated. FIG. 2 is an enlarged view of the illumination device in FIG. It is a top view.

  The projector 100 includes an illumination device 50 that forms and emits illumination light, and a color separation optical system that separates illumination light from the illumination device 50 into three colors of blue (B), green (G), and red (R). 40, a light modulation unit 60 that forms image light of each color, a cross dichroic prism 70 that combines color image light emitted from the light modulation unit 60 to form color image light, and a cross dichroic prism 70 And a projection optical system 80 that projects the passed image light.

  The illuminating device 50 emits light emitted from the first and second light source lamp units 10 and 20 which are lamps that generate light source light and the first and second light source lamp units 10 and 20 in substantially the same direction. A combining mirror 30 that combines by reflecting, a collimating optical system 34 that is a lens that collimates the illumination light combined by the combining mirror 30, and a first light that divides the collimated light beam into a plurality of partial light beams. A first and second fly-eye lenses 35 and 36; a polarization conversion element 37 that adjusts the polarization state of illumination light incident from the second fly-eye lens 36; and a superimposing lens for superimposing a plurality of partial light beams on the downstream side of the optical path. 38.

  As shown in FIG. 2 and the like, both the light source lamp units 10 and 20 of the lighting device 50 have the same structure and are first and second light sources that generate light source light including a visible light wavelength region. Second arc tubes 11 and 21, and first and second reflectors 12 and 22 that are reflection members that reflect light source light emitted from the first and second arc tubes 11 and 12, respectively. Yes. The first light source lamp unit 10 and the second light source lamp unit 20 are optical systems having the same structure, and the first arc tube 11 and the second arc tube 21 have the same specifications. Each arc tube 11, 21 is, for example, a high-pressure discharge lamp such as a high-pressure mercury lamp. At the time of lighting, the vapor pressure of mercury or the like enclosed in each glass tube is, for example, about 100 k to 1000 kPa (1 to 10 atm). Become. As a result, each arc tube 11, 21 generates substantially white light source light having a light quantity sufficient for image light formation. The 1st reflector 12 and the 2nd reflector 22 are arrange | positioned in the state which spaced apart in the mutually opposing state, and shared the optical axis RX on the same axis | shaft. The inner surfaces of the reflectors 12 and 22 form a locus obtained by rotating a free curve obtained by correcting an ellipse around the optical axis. That is, each of the reflectors 12 and 22 has a free curved surface that approximates a spheroidal surface as a reflecting surface. Therefore, the first reflector 12 uses the axis passing through the first focal point F1a and the second focal point F2a corresponding to the basic spheroidal surface as the optical axis RX. Similarly, the second reflector 22 uses an axis passing through the first focus F1b and the second focus F2b as the optical axis RX. The light emission points of the first and second arc tubes 11 and 21 substantially coincide with the first focal points F1a and F1b of the first and second reflectors 12 and 22, respectively. The light source light generated from the second arc tubes 11 and 21 is emitted from the opening OP toward the synthesis mirror 30 so as to be condensed as the emitted light IL.

  Here, the optical axes RX of the reflectors 12 and 22 are perpendicular to the illumination optical axis OC of the illuminating device 50, and the reflectors 12 and 22 are arranged symmetrically about the illumination optical axis OC. . Therefore, the composite mirror 30 is disposed in the middle of the first light source lamp unit 10 and the second light source lamp unit 20 on the optical axis RX. In the figure, the direction of the optical axis RX is the x direction, and the direction of the illumination optical axis OC is the z direction. Further, the illumination device 50 is incorporated in the projector 100 shown in FIG. 1 so that the illumination optical axis OC is the same as the system optical axis OA.

  The composite mirror 30 is formed on the side surface of the prism 30p having a triangular prism shape, the first reflecting surface 30a corresponding to the emitted light IL from the first light source lamp unit 10, and the emitted light IL from the second light source lamp unit 20. And a corresponding second reflecting surface 30b. More specifically, the shape of the composite mirror 30 is such that one end of the first reflecting surface 30a and the second reflecting surface 30b are connected, and the apex side end portion PK that is an edge portion is formed. A pair of rear-side end portions EG and the apex-side end portions PK, which are the other ends of the reflecting surfaces 30a and 30b, are connected to form a reflecting portion in a V shape in plan view. The first reflecting surface 30a provided on the first reflector 12 and the second reflecting surface 30b provided on the first reflector 12 are arranged so as to be symmetric with respect to the illumination optical axis OC. The first light source lamp unit 10 and the second light source lamp unit 20 are arranged symmetrically about the illumination optical axis OC. Here, in particular, the intersection CS between the first reflecting surface 30a and the optical axis RX is located upstream of the second focal point F2a of the first reflector 12 in the optical path. Similarly, the intersection CS of the second reflecting surface 30b and the optical axis RX is also located upstream of the second focal point F2b of the second reflector 22 by the same amount as the first reflecting surface 30a. As described above, in the present embodiment, the positions where the reflecting surfaces 30a and 30b are appropriately shifted from the second focal points F2a and F2b to the upstream side of the optical path instead of the corresponding second focal points F2a and F2b or the vicinity thereof are used as a reference. It has been arranged. Thereby, although mentioned later for details, in the synthetic | combination mirror 30, the light from both light source lamp units 10 and 20 can be synthesize | combined in the state which adjoined.

  Hereinafter, the synthesis of light by the two light source lamp units 10 and 20 and the synthesis mirror 30 will be described with reference to FIGS. 3, 4A and 4B. FIG. 3 is a cross-sectional view schematically showing the state of light emitted from the first light source lamp unit 10. In the drawing, the main light beam line is shown as a light beam IB of the emitted light IL to be emitted, and the outer shape of the light beam by the actual actual emitted light IL as a whole is schematically shown as a contour RD. Since the second light source lamp unit 20 (see FIG. 2) has the same structure as the first light source lamp unit 10, the description and illustration thereof are omitted.

  In the first light source lamp unit 10 of FIG. 3, the light emitting point of the first arc tube 11 substantially coincides with the first focal point F <b> 1 a of the first reflector 12. The light source light emitted from the light emitting point is reflected at each point on the reflecting surface 12a of the first reflector 12 through the glass tube 11a of the first light emitting tube 11 as shown by the main light beam IB. Is emitted as outgoing light IL from the opening OP of the reflector 12. Note that, regarding the emitted light IL, the spot diameter of the light beam when emitted from the opening OP is equal to the diameter D1 of the reflector 12. Here, it is assumed that the light emission point of the first arc tube 11 completely coincides with the first focal point F1a, and that the light source light emitted radially from the first focal point F1a goes straight without being refracted and travels straight through the first reflector. When the light is reflected at 12, the light having the theoretical virtual light beam shape VL indicated by the dotted line in the figure is emitted and condensed at the second focal point F2a. However, in practice, for example, the glass tube 11a constituting the first arc tube 11 has a structure that can withstand at least the vapor pressure and temperature generated in the internal space at the time of lighting. It has a thickness. For this reason, the glass tube 11a gives, for example, an effect as a convex lens (hereinafter referred to as a lens effect) to the transmitted light, although it is slightly. Further, the arc position of the first arc tube 11 also has a certain width, and does not exactly coincide with the first focal point F1a. Due to these influences, the actual emitted light IL is not condensed at the second focal point F2a or in the vicinity thereof, as shown in the main light beam IB, for example. In order to deal with such various factors, the curved surface shape of the reflecting surface 12a of the first reflector 12 is a curvature-corrected shape as described above. Although the minimum value of the light beam cross section of the emitted light IL is made as small as possible by the correction, the emitted light IL does not necessarily converge to one point at the second focal point F2a as ideal. For example, when the influence of the lens effect by the convex glass tube 11a is large, generally, the emitted light IL tends to be condensed on the upstream side of the optical path from the second focal point F2a. Therefore, for example, as shown in FIG. 3, the virtual light beam shape VL is condensed at the second focal point F2a, whereas the actual emitted light IL is on the upstream side of the optical path with respect to the illumination optical axis OC upper point F2a. At the position of the point K, the light is condensed in a state where the light beam cross section is minimized. That is, the outline RD, which is the outer shape of the light beam of the emitted light IL, has a minimum cross section cut perpendicularly to the illumination optical axis OC at the point K, and forms a beam waist BW (Beam Waist). When viewed along the illumination optical axis OC, the contour RD of the emitted light IL is greatly expanded before and after the beam waist BW.

  As described above, the actual luminous flux of the outgoing light IL is shifted by the distance Δt from the second focal point F2a to the upstream side of the optical path along the optical axis RX, not the second focal point F2a, due to the lens effect of the glass tube 11a. It has a shape with the position of the point K as the minimum position. In this way, the illumination device 50 according to the present embodiment takes into consideration that the second focus F2a and the minimum position of the contour RD of the light beam of the emitted light IL do not match.

  In the illuminating device 50, as described above, the combining mirror 30 has the reflecting surfaces 30a and 30b arranged with reference to the position of the beam waist BW, which is the position where the beam cross section of the emitted light IL, that is, the beam size is minimized. ing. 4A and 4B, FIG. 4A shows the position of the first reflecting surface 30a of the composite mirror 30 with respect to the output light IL, that is, the reflection position of the output light IL at the composite mirror 30. FIG. It is a figure for demonstrating, FIG.4 (B) is a figure of the comparative example. Since the second reflecting surface 30b has the same configuration as the first reflecting surface 30a due to symmetry, description and illustration are omitted. As shown in FIG. 4A, here, the point K which is the center position of the beam waist BW and the intersection CS between the optical axis RX of the first reflector 12 and the first reflecting surface 30a of the combining mirror 30 Match. In this case, as shown in the drawing, the width a1 from the intersection CS to the apex-side end portion PK that is the edge portion can be set to a small value substantially equal to the radius width a2 of the beam waist BW. Therefore, as shown in FIG. 2 etc., the emitted light IL from the two directions by the two light source lamp units 10 and 20 can be combined in a state where they are closer to each other. In this case, it is also possible to suppress the loss of light due to the light beam being partially blocked. Therefore, the illumination light SL formed by the composite mirror 30 is close to an ideal state and can be used more efficiently. In contrast, as shown in FIG. 4B, when the intersection CS between the optical axis RX and the reflecting surface 30a coincides with the second focal point F2a of the first reflector 12, the position of the beam waist BW is Since it moves away from the reflecting surface 30a, the outline RD of the emitted light IL formed on the reflecting surface 30a becomes wider than in the case of FIG. 4A, that is, the luminous flux sectional area of the emitted light IL becomes larger. Therefore, if the outgoing light IL from the two directions is too close, the light loss may increase.

  Further, for example, as shown in FIG. 2, the composite mirror 30 emits the emitted light IL emitted from the first and second light source lamp units 10 and 20 by the first and second reflecting surfaces 30 a and 30 b, respectively. Reflects in approximately the same direction. More specifically, first, in the composite mirror 30, the angle α formed by the first reflecting surface 30a and the second reflecting surface 30b is about 92 °, for example. As a result, the outgoing light IL emitted from each of the light source lamp units 10 and 20 has an angle θ (about 2 °) with the central axis CX slightly inclined with respect to the illumination optical axis OC on each of the reflection surfaces 30a and 30b. It is reflected in the state to do. The outgoing light IL from the opposite direction due to the reflection by the composite mirror 30 is combined by being reflected in substantially the same direction, and the illumination light SL is formed. The formed illumination light SL is incident on a collimating optical system 34 that is an optical system located on the downstream side of the optical path of the combining mirror 30.

  The collimating optical system 34 is a condensing lens that synthesizes the reflected light, and collimates the illumination light SL synthesized into one light beam by reflection at the synthesizing mirror 30. The illumination light SL emitted from the collimating optical system 34 enters the first and second fly-eye lenses 35 and 36 that are the uniformizing optical system in a substantially collimated state.

  The first and second fly-eye lenses 35 and 36 are each composed of a plurality of element lenses 35a and 36a arranged in a matrix, and are collimated by the element lenses 35a and 36a via the collimating optical system 34. Divide the light and collect and diverge it individually. More specifically, the first fly-eye lens 35 has a function as a light beam splitting optical element that splits a light beam of light that has passed through the collimating optical system 34 into a plurality of partial light beams, and the illumination optical axis OC, that is, system light. The plurality of element lenses 35a described above are provided in a plane orthogonal to the axis OA. The contour shape of each element lens 35a is substantially similar to the shape of illuminated areas (effective pixel areas in which image information is formed) on the liquid crystal panels 61b, 61g, 61r in the light modulation section 60 of FIG. It is set to make. The second fly-eye lens 36 is an optical element that adjusts the divergence angles of a plurality of partial light beams divided by the first fly-eye lens 35 described above. The second fly-eye lens 36 includes the above-described plurality of element lenses 36a in a plane orthogonal to the system optical axis OA in the same manner as the first fly-eye lens 35, but is intended to adjust the divergence angle. The contour shape of each element lens does not have to correspond to the illuminated area of the liquid crystal panels 61b, 61g, 61r.

  As described above, the illumination light SL formed through the first and second fly-eye lenses 35 and 36 enters the polarization conversion element 37. The polarization conversion element 37 has a PBS array and has a role of aligning the polarization direction of each partial light beam divided by the first fly-eye lens 35 with one direction of linearly polarized light. The specific structure and the like will be described. The polarization conversion element 37 has a configuration in which polarization separation films 37a and reflection mirrors 37b that are inclined with respect to the system optical axis OA are alternately arranged. The former polarization separation film 37a transmits one polarized light beam among the P-polarized light beam and S-polarized light beam included in each partial light beam, and reflects the other polarized light beam. The other polarized light beam reflected is bent in the optical path by the latter reflecting mirror 37b, and is emitted in the emission direction of the one polarized light beam, that is, the direction along the system optical axis OA. One of the emitted polarized light beams is polarized and converted by a phase difference plate 37c provided in a stripe shape on the light beam exit surface of the polarization conversion element 37, and the polarization directions of all the polarized light beams are aligned. By using such a polarization conversion element 37, it is possible to align the light beam emitted from the illumination device 50 with a polarized light beam in one direction, thereby improving the utilization factor of light used in the light modulation unit 60 of FIG. Can be made.

  The superimposing lens 38 condenses a plurality of partial light beams that have passed through the first fly-eye lens 35, the second fly-eye lens 36, and the polarization conversion element 37, and the liquid crystal panels 61b and 61g of the light modulation unit 60 in FIG. It is a superimposing optical element for making it superimpose and enter on the 61r image formation area. The light beam emitted from the superimposing lens 38 is emitted to the color separation optical system 40 on the downstream side of the optical path while being made uniform by superposition. That is, the illumination light that has passed through both the fly-eye lenses 35 and 36 and the superimposing lens 38 passes through a color separation optical system 40 that will be described in detail below. The image forming area is uniformly illuminated.

  In the illuminating device 50, as described above, the outgoing light IL emitted from each of the light source lamp units 10 and 20 has an angle θ (about 2 °) in which the central axis CX is slightly inclined with respect to the illumination optical axis OC. In this state, illumination light is incident on each optical system on the downstream side of the optical path. By applying such an optical design, for example, an arc image can be formed in each element lens 36a of the second fly's eye lens 36 for any of the two outgoing lights IL, thereby improving the light utilization efficiency. Can be improved.

  As described above, in the illuminating device 50, the second focal points F2a and F2b that should be based on the positions of the reflecting surfaces 30a and 30b with respect to the light source lamp units 10 and 20 corresponding to the light beam shape of the emitted light IL. Since the light beam cross section of the outgoing light IL can be reduced on the reflecting surface 30a by setting the upstream side of the optical path, the outgoing light IL from both the light source lamp units 10 and 20 is more combined in the synthesis of the outgoing light IL. Can be close. As a result, more light can be reflected in an appropriate state without waste, and the light utilization efficiency can be improved. Also, at this time, the conventional characteristics of the other optical designs for improving the light use efficiency such as the setting of the reflection angles of the first and second reflectors 12 and 22 and the combining mirror 30 may be retained. Is possible.

  Hereinafter, returning to FIG. 1, each configuration of the projector 100 arranged on the downstream side of the optical path from the illumination device 50 will be described.

  The color separation optical system 40 includes first and second dichroic mirrors 41a and 41b, reflection mirrors 42a, 42b, and 42c, field lenses 43b, 43g, and 43r, and relay lenses 45 and 46. Among these, the first and second dichroic mirrors 41a and 41b separate the illumination light into three light beams of blue (B) color light, green (G) color light, and red (R) color light. Each of the dichroic mirrors 41a and 41b is an optical element obtained by forming a dielectric multilayer film having a wavelength selection function that reflects a light beam in a predetermined wavelength region and transmits a light beam in another wavelength region on a transparent substrate. Yes, they are arranged in an inclined state with respect to the system optical axis OA. The first dichroic mirror 41a reflects the blue light LB among the three colors B, G, and R, and transmits the green light LG and the red light LR. The second dichroic mirror 41b reflects the green light LG out of the incident green light LG and red light LR and transmits the red light LR. The field lenses 43b, 43g, and 43r for each color provided on the emission side of the color separation optical system 40 have each partial light beam emitted from the second fly-eye lens 36 and incident on the light modulation unit 60 on the system optical axis OA. On the other hand, it is provided so as to have an appropriate degree of convergence or divergence. The pair of relay lenses 45 and 46 are disposed on a red third optical path OP3 that is relatively longer than the blue first optical path OP1 and the green second optical path OP2. These relay lenses 45 and 46 transmit the image formed immediately before the incident-side first relay lens 45 to the field lens 43r on the exit side almost as it is, so that the light use efficiency due to light diffusion or the like is achieved. Is prevented.

  In the color separation optical system 40, the illumination light SL emitted from the illumination device 50 first enters the first dichroic mirror 41a. The blue light LB reflected by the first dichroic mirror 41a is guided to the first optical path OP1, and enters the field lens 43b via the reflection mirror 42a. Further, the green light LG transmitted through the first dichroic mirror 41a and reflected by the second dichroic mirror 41b is guided to the second optical path OP2 and enters the field lens 43g. Further, the red light LR that has passed through the second dichroic mirror 41b is guided to the third optical path OP3, and enters the field lens 43r through the reflection mirrors 42b and 42c and the relay lenses 45 and 46.

  The light modulation unit 60 includes three liquid crystal panels 61b, 61g, and 61r on which illumination lights LB, LG, and LR of three colors respectively enter, and three sets of polarized light disposed so as to sandwich the liquid crystal panels 61b, 61g, and 61r. Filters 62b, 62g, and 62r are provided. Here, for example, the liquid crystal panel 61b for blue light LB and the pair of polarizing filters 62b and 62b sandwiching the liquid crystal panel 61b constitute a liquid crystal light valve for two-dimensionally modulating the luminance of illumination light based on image information. . Similarly, the liquid crystal panel 61g for green light LG and the corresponding polarizing filters 62g and 62g also constitute a liquid crystal light valve, and the liquid crystal panel 61r for red light LR and the polarizing filters 62r and 62r also have a liquid crystal light valve. Constitute. Each of the liquid crystal panels 61b, 61g, 61r is a liquid crystal which is an electro-optical material hermetically sealed between a pair of transparent glass substrates. For example, each of the liquid crystal panels 61b, 61g, 61r is a polysilicon TFT as a switching element, The polarization direction of the polarized light beam incident on the light is modulated.

  In the light modulation unit 60, the blue light LB guided to the first optical path OP1 illuminates the image forming region in the liquid crystal panel 61b through the field lens 43b. The green light LG guided to the second optical path OP2 illuminates the image forming area in the liquid crystal panel 61g through the field lens 43g. The red light LR guided to the third optical path OP3 illuminates the image forming area in the liquid crystal panel 61r via the first and second relay lenses 45 and 46 and the field lens 43r. Each of the liquid crystal panels 61b, 61g, 61r is a non-light-emitting and transmissive light modulation device for changing the spatial distribution of the polarization direction of incident illumination light. The color lights LB, LG, and LR incident on the liquid crystal panels 61b, 61g, and 61r are polarized in units of pixels in accordance with drive signals or control signals input as electrical signals to the liquid crystal panels 61b, 61g, and 61r. The state is adjusted. At that time, the polarization filters 62b, 62g, and 62r adjust the polarization direction of the illumination light incident on the liquid crystal panels 61b, 61g, and 61r, and a predetermined amount of light is emitted from the liquid crystal panels 61b, 61g, and 61r. The modulated light in the polarization direction is extracted. As described above, the liquid crystal panels 61b, 61g, 61r and the polarizing filters 62b, 62g, 62r form image lights of the corresponding colors.

  The cross dichroic prism 70 is a light combining optical system that forms a color image by combining image light modulated for each color light emitted from each liquid crystal panel 61b, 61g, 61r. The cross dichroic prism 70 has a substantially square shape in plan view in which four right angle prisms are bonded together, and a pair of dielectric multilayer films 71 and 72 intersecting in an X shape are formed at the interface where the right angle prisms are bonded to each other. Is formed. One first dielectric multilayer film 71 reflects blue light, and the other second dielectric multilayer film 72 reflects red light. The cross dichroic prism 70 reflects the blue light LB from the liquid crystal panel 61b by the first dielectric multilayer film 71 and emits the green light LG from the liquid crystal panel 61g to the first and second dielectrics. The red light LR from the liquid crystal panel 61r is reflected by the second dielectric multilayer film 72 and emitted to the left in the traveling direction through the multilayer films 71 and 72.

  The image light combined by the cross dichroic prism 70 in this way is projected as a color image on a screen (not shown) at an appropriate magnification through a projection optical system 80 as a magnification projection lens.

  FIG. 5 shows the distance along the optical axis RX from the opening OP of the light source lamp unit 10 shown in FIG. 3 and the beam size of the outgoing light IL, that is, the contour RD when the outgoing light IL is cut in a cross section perpendicular to the optical axis RX. It is a graph which shows the relationship with the spot diameter which is a magnitude | size. That is, in FIG. 5, the horizontal axis indicates the distance from the opening OP along the optical axis RX, and the vertical axis indicates the spot diameter of the contour RD. Therefore, for example, the value of the spot diameter of the contour RD on the opening OP is the diameter D1 of the reflector 12. As already described with reference to FIG. 3 and the like, the cross-sectional area cut perpendicularly to the optical axis RX of the contour RD is minimum at the position of the point K where the beam waist BW is formed. Therefore, also in the graph of FIG. 5, the spot diameter of the contour RD is the smallest at the position of the point K. On the other hand, at the second focal point F2a, the spot diameter of the contour RD is relatively large. In the example shown in FIG. 4A, the position of the point K and the position of the point CS are made to coincide with each other, but it is sufficient that the spot diameter is sufficiently small even at a position near the point K. However, the position of the point K and the position of the point CS do not necessarily coincide with each other. For example, the point K may be on the intersection of the optical axis RX and the illumination optical axis OC.

  In the above, in determining the contour RD of the emitted light IL, the illuminance distribution of the light beam cross section in the vicinity of the beam waist BW of the emitted light IL can be used as a reference. FIG. 6A is a cross-sectional view for explaining an example of the illuminance distribution on the reflecting surface of the composite mirror of the lighting device. FIG. 6A is a diagram showing an illuminance distribution in a cross section obtained by cutting the light beam of the emitted light IL perpendicularly to the optical axis RX. That is, the outermost edge portion in the figure is the contour RD of the emitted light IL. 6B is a graph showing the illuminance distribution corresponding to FIG. 6A. Of the x and y axes in the plane shown in FIG. 6A, the output light IL on the x axis. It represents the size of illuminance. The origin O in FIG. 6B corresponds to the origin O that is the intersection of the x-axis and the y-axis in FIG. 6A, and as shown in the graph, the illuminance of light is generally the center of the luminous flux. It is so strong that it gets weaker as you go around. Therefore, as far as the contour RD of the emitted light IL, a threshold value may be set for the intensity of light in FIG. 6B, for example, depending on whether or not it is equal to or greater than the threshold value. By determining the contour RD of the emitted light IL, the position of the beam waist BW, which is the position where the beam size of the emitted light IL is minimized, is determined. Further, by this, the position (that is, the value of the distance Δt) and the size (that is, the value of the width a2) of the beam waist BW are determined, and accordingly, the width a1 of the combining mirror 30 in FIG. The arrangement position of each optical system including the value of is determined.

  As described above, the illuminating device 50 according to the present embodiment optimizes the shape of the light flux on the reflecting surfaces 30a and 30b of the emitted light IL by considering the distances of the reflectors 12 and 22 with respect to the combining mirror 30. High intensity light can be emitted with certainty. Further, since the projector 100 according to the present embodiment can emit high-intensity light by using the illumination device 50 having the structure shown in FIG. 2 or the like as a light source, each of the liquid crystal panels 61b, 61g, 61r can be appropriately used. Illumination is possible, and a high-luminance image can be projected.

  The present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof. For example, the following modifications are possible.

  First, in the said embodiment, although the 1st and 2nd light source lamp units 10 and 20 are shifted and arrange | positioned by the same amount, not only this but each light source lamp unit 10 and 20 is fine-tuned separately. It may be a thing.

  In the above embodiment, the beam waist BW is located upstream of the second focal point F2a due to the lens effect of the convex glass tube 11a. However, depending on the shape of the glass tube 11a, for example, the generated lens It is also conceivable that the effect is opposite to that described above and the beam waist BW is located on the downstream side of the optical path from the second focal point F2a. In order to cope with such a case, the reflecting surfaces 30a and 30b of the composite mirror 30 may be arranged based on positions appropriately shifted from the second focal points F2a and F2b to the downstream side of the optical path.

  As each arc tube 11 and 21 used for each light source lamp unit 10 and 20, other high pressure discharge lamps such as a metal halide lamp may be used instead of the high pressure mercury lamp.

  Moreover, in the said embodiment, although the illuminating device 50 is made from the 1st and 2nd light source lamp units 10 and 20 to the superimposition lens 38, for example from the 1st and 2nd light source lamp units 10 and 20 to the synthetic | combination mirror 30, for example. It is good also as an illuminating device which distributes as one article.

  In the above embodiment, an example in which the illumination device 50 is applied to the projector 100 using the transmissive liquid crystal light valve has been described. However, the embodiment can also be applied to a projector using the reflective liquid crystal light valve. .

  In the above-described embodiment, the projector 100 uses the liquid crystal light valves 35a, 35b, and 35c as image forming elements in the image forming optical unit 30, but a light modulation device such as a device in which pixels are configured by micromirrors. It is also possible to use image forming means such as a film or a slide.

It is a conceptual diagram explaining the projector which concerns on 1st Embodiment. It is a figure explaining the structure of the illuminating device among projectors. It is a conceptual diagram explaining the emitted light from a lamp | ramp. (A), (B) is the figure for demonstrating reflection of the light in the synthetic | combination mirror in one Example of an illuminating device, and the figure of the comparative example. It is a graph which shows the relationship between the distance from a lamp | ramp, and the beam size of emitted light. (A), (B) is sectional drawing for demonstrating the illumination intensity distribution in the reflective surface of the synthetic | combination mirror of an illuminating device, and the graph of the illumination intensity distribution.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 50 ... Illuminating device 10, 20 ... Light source lamp unit 11, 21 ... Arc tube, 12, 22 ... Reflector, 30 ... Synthetic mirror, 30a, 30b ... Reflecting surface, 100 ... Projector, IL ... Outgoing light, RX ... Reflector Optical axis, CX ... Center axis, OC ... Illumination optical axis, OA ... System optical axis, SL ... Illumination light, OP ... Aperture, EG, PK ... Synthetic mirror end, F1a, F1b ... First focus, F2a, F2b ... Second focal point, CS: intersection of reflector optical axis and reflecting surface, VL: virtual luminous flux shape, IB: luminous flux, RD: contour of luminous flux, BW: beam waist, K: point at minimum position of luminous flux section, D1 ... Reflector diameter, Δt: distance from the second focal point to the minimum position of the beam cross section, O: center point of the beam cross section

Claims (10)

The first and second light-emitting tubes that respectively generate light source light and the light source light generated from the first and second light-emitting tubes are emitted so as to condense, and are spaced apart from each other. First and second lamps having first and second reflectors,
A reflective surface disposed between the first and second lamps and disposed corresponding to a minimum position of a beam size of light emitted from at least one of the first and second lamps; An illuminating device comprising: a V-shaped composite mirror that synthesizes each of the emitted lights respectively emitted from the second lamps by reflecting them in the same direction.   The composite mirror has first and second reflecting surfaces arranged corresponding to the minimum positions of the beam sizes of light emitted from both the first and second lamps as the reflecting surfaces, respectively. Item 2. The lighting device according to Item 1.   The minimum position of the beam size of the emitted light from at least one of the first and second reflectors is at or near the intersection of the optical axis of the reflector and the reflecting surface of the combining mirror corresponding to the reflector. The lighting device according to claim 1 or 2.   The lighting device according to any one of claims 1 to 3, wherein the first and second reflectors are elliptical.   The illuminating device according to claim 4, wherein a minimum position of a beam size of emitted light from at least one of the first and second reflectors is located upstream of a corresponding second focal point of the reflector.   The illuminating device according to claim 4, wherein a minimum position of a beam size of emitted light from at least one of the first and second reflectors is located on the downstream side of the optical path with respect to the position of the second focal point of the corresponding reflector.   The lighting device according to any one of claims 1 to 6, wherein the first and second lamps are high-pressure discharge lamps of either a high-pressure mercury lamp or a metal halide lamp.   The illumination according to any one of claims 1 to 7, wherein the first lamp and the second lamp are optical systems having the same specifications and are arranged symmetrically with respect to the combining mirror. apparatus.   The illumination device according to any one of claims 1 to 8, further comprising a collimating optical system that collimates the synthesized outgoing light on the downstream side of the optical path of the synthesis mirror. The lighting device according to any one of claims 1 to 9,
A light modulation device illuminated by illumination light from the illumination device;
A projector comprising: a projection optical system that projects image light that has passed through the light modulation device.

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