JPS59214075A - Ic substrate for active panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of designing an active panel using a semiconductor substrate.

Liquid crystal panels, which are non-luminescent displays, have been widely used in small portable devices such as wristwatches, calculators, and measuring instruments, taking advantage of their characteristics such as being able to be driven at low voltage and having low power consumption. These liquid crystal panels are widely used because conventional segment display panels that only display numbers are simple, but there are more flexible display formats.
Dot matrix panels, in which small display units (pixels) are arranged in an array vertically and horizontally, are attracting attention because a panel with a large display capacity and capable of high-quality display is desired.

However, similar to conventional segment display panels, this dot matrix panel is made by sealing liquid crystal between two glass substrates on which orthogonal transparent electrodes are formed, and applying complex signals between these orthogonal electrodes. Achieving a display using a multiplex driving method has problems such as the difficulty of increasing pixel density and the inability to increase the number of pixels. An active panel has been realized in which a switching element or an electric circuit is formed on the top of the active panel, and a signal applied to the liquid crystal driving electrode of each pixel is controlled to display light.

Dot matrix panels, in which pixels are arranged in an array, can be used for televisions, which can also display intermediate dimming, depending on the purpose of display, and for displaying characters, figures, etc. using binary coloring of white and black. They are broadly divided into panels, with different circuit configurations and required liquid crystal characteristics.

Figure 1 (1) * (2) shows an example of a pixel circuit of an active panel. FIG. 1 (1) is a circuit diagram of a pixel of a display panel for a television that can also display halftones. 1 is a pixel circuit included in one pixel, and display image data 2 is written into a signal holding capacitor 5 by turning on an N-channel field effect transistor 4 by a pixel selection signal 3. This is connected to the pixel electrode 6 formed on the top of each pixel, and applies an electric field to the liquid crystal 8 sealed between it and the transparent electrode 7 formed on the upper glass substrate, and is held in the signal holding capacitor 5. A display with gradations corresponding to the applied voltage is performed.

FIG. 1(2) is an example of a pixel circuit of a storage type active panel that can display two pixels, white and black, and statically hold display data. 9 is a pixel circuit included in one pixel, and optical image data 10 (DAT
A) and 11 (DATA) turn on the N-channel field effect transistors 13 and 14 by the pixel selection signal 12.
state and is written into a memory cell constituted by two inverters 15, 16. Using the data 17.18 of this memory cell, the low frequency liquid crystal drive signal 1
The clocked inverters 20 and 21 to which the clocked inverter 9 is input are opened and closed to change the phase of the liquid crystal drive signal applied to the pixel electrode 22. The same low frequency liquid crystal drive signal as 19 is input to the transparent electrode 23 of the upper glass substrate, and 24 is a liquid crystal sealed between them.

Now, normally, in order to design an active panel that uses these pixels as one display unit, as shown in Fig. 2, within the area occupied by one pixel 25, as shown in Fig. Design the mask pattern of the circuit and connect them with arrows 26,
As shown in 27.28.29, a method is used to create a mask pattern for all pixels on the screen by repeating (repeat) vertically and horizontally. In this design method, only a mask pattern for one pixel is designed, and then the entire screen can be designed by simple operations on CAD.

The size of the pixel, which is the unit of display, is determined mainly by the display purpose of the panel, and there is a considerable amount of space available to build a pixel circuit like the one shown in Figure 1. There are many. Therefore, they are typically designed under design rules that are much looser than the dimensional design rules achievable with current integrated circuit technology to make the panels easier to manufacture and to avoid lower yields due to defects. However, even when such design rules are used, a considerable area within the pixel is often left unused, and it is difficult to design by unnecessarily distributing elements and wiring in these extra areas. Even so, no improvement in yield can be expected.

FIG. 3 shows the configuration of the entire active panel when the screen portion is designed by repeating a mask pattern of one pixel as described above. 30 is shown in Figure 1 (1
) I This is a semiconductor substrate on which a pixel circuit and peripheral control circuit as shown in (2) are built. Pixels 31 with built-in pixel circuits are arranged vertically and horizontally to form a screen 32,
A liquid crystal layer is placed on this portion, and the sealant 33 prevents the liquid crystal layer from flowing out. A dashed line 34 indicates the upper glass substrate on which the transparent electrode is formed.

In such a dot matrix panel, as shown in Fig. 1 (1
), The display image data signal, 1-pixel selection signal, and liquid crystal drive signal that are input to the circuit in (2) run horizontally and vertically across the screen. It is necessary to incorporate a signal control circuit (shift register, etc.), a decoder circuit for the 9 pixel selection signals, and the like. In the design method shown in FIG. 2, pixel circuits are formed in the screen area, and peripheral circuits must be formed outside of this, but these circuits are formed from immediately adjacent to the screen to below the sealant 33. This is undesirable because it may lead to defects due to pressure on the board during panel assembly. Therefore, as shown in FIG. 3, the peripheral circuits 35, 36,
37.38 are designed. 59, 40, 41, and 42 are signal input terminals, and arrows 43 and the like indicate signal lines.

However, in this design method in which the peripheral circuit is built outside the sealant, the edge 44 of the screen and the edge 4 of the semiconductor substrate
The distance between the wafer and the wafer increases by 46 mm, which in turn causes an increase in the overall size of the semiconductor chip, resulting in a decrease in the number of chips that can be made from one wafer, and a decrease in yield. In addition, in small portable devices, such unnecessary outer periphery is a problem due to the design of the device itself.
I don't like the design.

The present invention aims to reduce the dimensions around the screen by consolidating the pixel circuits in the screen part and incorporating peripheral control circuits at the bottom of the screen, making it possible to reduce the size of the entire panel. This paper attempts to provide a method for designing panels.

FIG. 4 shows an example of the structure of an active panel according to the present invention. As in FIG. 3, 30 is a semiconductor substrate, 33 is a sealant for preventing liquid crystal from flowing out, and 34 is a glass substrate. 47 is a pixel electrode for driving the liquid crystal, and 48 is a pixel circuit that generates a signal for the pixel electrode. In the example shown in Figure 4, each pixel circuit is not built under the corresponding pixel electrode, but the pixel circuits are concentrated in the center of the screen in a shape that is almost similar to the arrangement of pixel electrodes on the display screen. It is formed by The signal at each pixel 'pi pole is guided from this integrated pixel circuit to the pixel electrodes over the entire screen of the display body, as shown by arrows 49, 50, etc. The peripheral control circuit described in FIG. 3 is built into the blank space of the screen created by the aggregation (51, 52, 53, 54). 5
5 and the like are signals from the peripheral control circuit to the pixel circuit. By concentrating the pixel circuits in the center of the screen in this way, a considerable amount of blank space is created, so the input signals (56, 57, 58, 59) to each peripheral control circuit must be guided in one direction on the panel. The input terminal 60 for the input signal can be formed centrally on one side of the panel, which facilitates mounting.

In this example, mask pattern design is easy when the number of rffI primes is small, but as the number of pixels increases, the number of signal wires from the pixel circuit to the entire screen increases significantly, and the length also increases. It is not suitable for such cases. Further, since the area where the peripheral control circuit elements are formed and the wiring area from the pixel circuit to the pixel electrode overlap, multilayer wiring is required.

By consolidating the pixel circuits in the center of the planning screen and building the peripheral control circuits in the blank bottom of the screen,
Since there is no need to form a circuit outside the seal as shown in Figure 3, the distance between the edge of the screen and the edge of the semiconductor substrate is 61.
can be designed with minimum dimensions, and only the area forming the signal input terminal 60 remains outside the sealant 33.
The entire panel can be made smaller.

FIG. 5 shows a second active panel according to the structure of the present invention.
An example was given. As described above, in the configuration example of FIG. 4 in which the entire pixel circuit is similarly reduced and the pixel circuit is formed in the center of the screen, the number of wiring increases as the number of pixels increases, making the design difficult. In the example shown in Figure 5, the pixel circuits for the pixels in the center of the screen are created below each pixel electrode as before, and only the pixel circuits at the periphery of the screen are consolidated, and the peripheral control circuits are created in the margins. be included.

As in FIG. 3, 30 is a semiconductor substrate, 33 is a sealant for preventing liquid crystal from flowing out, and 34 is an upper glass substrate.

In the pixel 62 in the rectangular area ABOD at the center of the screen, pixel circuits are built in one-to-one correspondence under the pixel electrodes, as in FIG. 3. Pixel circuits corresponding to the pixel electrodes in four directions around the screen are integrated into four areas (63, 64, 65, 66) close to the central area ABOD, and this screen Signals 68, 69, etc. are connected to the pixel electrodes 67 around the . 70.71 etc. are signals from the consolidated pixel circuit to the normal pixel circuit,
Display image data signals, 1-pixel selection signals, liquid crystal drive signals, etc. are wired while maintaining the relationship between rows and columns on the screen. 72
．． 73, 74.75 are peripheral control circuits, 76.77
．． 78 is an input signal to the peripheral control circuit. In this example as well, the signal input terminals 79 can be concentrated in one direction of the panel, and the distance between the edge of the screen and the edge of the semiconductor substrate can be reduced.

The size of the pixel area around the screen where the pixels are concentrated is determined by taking into account the scale of the peripheral control circuit to be built and the number of wires.
According to such a configuration, the number of signals sent from the pixel circuit to the pixel electrode is greatly reduced compared to the example shown in FIG. 4, and the length thereof is also shortened, so that it is particularly suitable for designing a large panel.

FIG. 6 shows the third active panel according to the structure of the present invention.
An example was given. In this example, the screen is divided into a plurality of blocks (six blocks in the figure), and within each block, pixel circuits are concentrated and formed in the center, as in FIG. 4.

As in FIG. 3, 30 is a semiconductor substrate, 33 is a sealant for preventing liquid crystal from flowing out, and 34 is an upper glass substrate.

An integrated pixel circuit 8° is formed in the center of the block, and signals 82, 83, etc. are sent from the pixel circuit to the pixel electrode 81 in the block. Each block consists of such aggregated pixel circuits (8o.

84, 85), 86, 87, 88), and peripheral control circuits 89, 90, etc. are built into the blocks around the screen. 91, 92, etc. are signals between the aggregated pixel circuits, and 93, 94, etc. are input signals to the peripheral control circuit. Similar to the examples shown in FIGS. 4 and 5, the signal input terminals 95 can be concentrated in one direction of the panel, and the distance between the edge of the screen and the edge of the semiconductor substrate can be reduced.

Further, with such a configuration, it is possible to prevent the wiring length from increasing as shown in FIG. 4.

As described above, as in the present invention, the pixel circuits of the entire screen or a part of the screen are integrated regardless of the position of the pixel electrodes, and peripheral control circuits are built into the blank space created at the bottom of the screen. This eliminates the inconvenience of conventionally building one peripheral control circuit outside the display screen, which increases the distance between the edge of the screen and the edge of the semiconductor substrate and increases the size of the semiconductor chip. It is possible to reduce manufacturing costs, simplify panel mounting, and improve design.

[Brief explanation of the drawing]

FIGS. 1(1) and 1(2) are examples of pixel circuits of an active panel. FIG. 2 is a diagram for explaining a normal method of designing an active panel. FIG. 3 shows an example of the overall configuration of an active panel having a screen designed by the method shown in FIG. FIG. 4 to FIG. 6 are examples of the configuration of an active panel having a screen designed using the integrated pixel circuit of the present invention. Applicant: Suwa Seikosha Co., Ltd. Figure 5 3Q Figure 6

Claims (1)

[Claims] In an active panel that displays liquid crystal by controlling signals applied to pixel electrodes by electric circuits formed on a semiconductor substrate, a pixel circuit corresponding to the pixels of the entire screen of the panel or a portion thereof are formed in a specific area at the bottom of the screen, and peripheral control circuits, signal lines, etc. are formed in the area at the bottom of the screen other than the area where the aggregated pixel circuits are formed. Integrated circuit board for active panels.