JPH06347816A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To provide a liquid crystal display element which has such a structure to allow production without making the production process intricate and difficult and with the higher fineness and higher density of pixels are attained. CONSTITUTION:The pixel size of apparent one pixel of a screen is made finer while pixel size of the one pixel of a first liquid crystal cell 101 and a second liquid crystal cell 103 are held intact. The driving voltage to be impressed to the first liquid crystal cell 101 and the driving voltage to be impressed to the second liquid crystal cell 103 are made into different waveforms while these voltage are synchronized with each of frame periods, thereby, the first liquid crystal 101 and the second liquid crystal cell 103 can be discretely driven, and the display state each of the apparent pixels finely divided can be set by the combination of the display states of these liquid crystal cells 101, 103.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a high definition liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal display devices are widely used as information processing devices such as word processors and personal computers, and display devices such as small televisions and projection televisions. In recent years, research and development of liquid crystal display elements that support high-speed response and high definition have been advanced, and liquid crystal display elements have a thin and light display screen and high image quality.
It is attracting attention as a device that can be made larger.

An example of the structure of a conventional general liquid crystal display device is shown in FIG. FIG. 3 shows the case of a simple matrix type liquid crystal display element. A plurality of scan electrodes 303 made of transparent electrodes such as ITO are arranged in a row on a glass substrate 301, and a scan electrode substrate 307 having an alignment film 305 formed so as to cover the scan electrodes 303, and the scan electrode substrate 3
07, a plurality of signal electrodes 309 are arranged in a line on the glass substrate 311, and the alignment film 31 is formed so as to cover the signal electrodes 309.
3 and the signal electrode substrate 315 on which the substrate 3 is formed, and these substrate 3
07 and 315 are arranged to face each other with a gap interposed between them by a spacer 317, and the liquid crystal composition that forms a pixel by being sandwiched between the scanning electrode 303 and the signal electrode 309 that are sealed in the substrate gap and face each other. The main part of the liquid crystal cell is constituted by 319, and the main part of the liquid crystal display element is constituted by polarizing plates 321 and 323 which are attached to the liquid crystal cell so as to sandwich the liquid crystal cell from above and below.

In order to improve the definition of pixels of such a liquid crystal display device, it is necessary to make the dimensions of the scanning electrodes 303 and the signal electrodes 309, which are the electrodes forming the pixels, smaller than ever. Become. Alternatively, although not shown in FIG. 3, even in the case of an active matrix type liquid crystal display element, it is necessary to further reduce the size of the pixel electrode.

However, as such, the scan electrodes 303
Further, if the dimensions of the signal electrode 309 are further miniaturized, there is a limit to the manufacturing capability such as the resolution of the resist pattern and the etching accuracy when the scanning electrode 303 and the signal electrode 309 are formed from the transparent conductive film by photolithography. However, there is a problem that it is practically difficult to miniaturize beyond its manufacturing capability. Further, when the scan electrode 303 and the signal electrode 309 are miniaturized even to the limit of the manufacturing capacity, the scan electrode 303 made of a transparent conductive film during the manufacturing process.
Further, there is a problem that the signal electrode 309 and the like are significantly damaged and the manufacturing yield is significantly reduced.

[0006]

The present invention has been made to solve such a problem, and its object is to provide a structure which can be manufactured without making the manufacturing method complicated or difficult. An object of the present invention is to provide a liquid crystal display device that realizes high definition and high density of pixels.

[0007]

In order to solve the above-mentioned problems, the present invention comprises a first substrate having a first electrode formed thereon and a second electrode arranged so as to face the first electrode. Second
Liquid crystal cell having a first liquid crystal layer enclosed and sandwiched between the first substrate and the second substrate, and the first electrode of the first liquid crystal cell. And the second
A first drive circuit for applying a drive voltage of the first waveform to the electrode of, a third substrate on which the third electrode is formed, and a fourth electrode arranged to face the third electrode. And a second liquid crystal layer enclosed and sandwiched between the third substrate and the fourth substrate.
A second liquid crystal cell arranged so that at least a part of the plurality of pixels overlaps with the pixel; the third electrode and the fourth electrode of the second liquid crystal cell; and the first liquid crystal cell. A second drive circuit for applying a drive voltage of a second waveform different from the applied drive voltage of the first waveform in synchronization with the frame period of the drive voltage of the first waveform. Is characterized by.

The pixel size of one pixel of the first liquid crystal cell and the pixel size of one pixel of the second liquid crystal cell are set to the same size, and the panel size of the first liquid crystal cell and the second liquid crystal cell are set to the same size. The size of the panel of the liquid crystal cell is the same as that of the first liquid crystal cell, and the pixels of the first liquid crystal cell and the pixels of the second liquid crystal cell are arranged so that their planar positions are shifted by, for example, 1/2 pixel dimension. It is desirable that four pixels of the second liquid crystal cell overlap with one pixel of the second liquid crystal cell by 1/4 pixel size. In this way, the dimensional specifications of the first liquid crystal cell and the dimensional specifications of the second liquid crystal cell can be made to be the same, so that it is possible to avoid complication of the manufacturing method of making either one smaller. , And the pixel size of 1 pixel
This is because it can be miniaturized to 1/4. However, the present invention is not limited to this, and the pixel size of one pixel of the first liquid crystal cell is different from the pixel size of one pixel of the second liquid crystal cell, and one pixel of the first liquid crystal cell is used. On the other hand, it is also possible to arrange, for example, two pixels of the second liquid crystal cell so as to overlap each other. At this time, the pixel size of the second liquid crystal cell is preferably 10 times or less to 1/10 or more of the pixel size of the first liquid crystal cell.

In the case of a liquid crystal cell using a nematic liquid crystal as the liquid crystal layer, polarizing plates may be used above and below the liquid crystal cell. Needless to say, a color filter or the like may be used together when performing color display.

[0010]

According to the present invention, the pixel of the first liquid crystal cell and the second liquid crystal cell
By arranging the first liquid crystal cell and the second liquid crystal cell so that the two-dimensional position of the first liquid crystal cell and the pixel of the second liquid crystal cell are displaced from each other, one pixel of the first liquid crystal cell is provided with a plurality of second liquid crystal cells At least a part of the pixels overlap, and the apparent number of pixels increases by the number of overlapping subdivisions. As a result, the 1-pixel size of the first liquid crystal cell and the second liquid crystal cell remains the same, and
The pixel size of the pixel can be miniaturized. At this time, by making the drive voltage applied to the first liquid crystal cell and the drive voltage applied to the second liquid crystal cell have different waveforms in synchronization with each frame period, By driving the two liquid crystal cells individually and combining the display states of these liquid crystal cells, it is possible to set the above-mentioned apparent display state of each pixel subdivided into a plurality of pixels. Conversely speaking, the first drive voltage and the second drive voltage having waveforms that can control the display state of each apparently subdivided pixel are generated so as to generate the first drive voltage and the second drive voltage. It goes without saying that the drive circuit and the second drive circuit are respectively formed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid crystal display device according to the present invention will be described below in detail with reference to the drawings. FIG. 1 is a partially omitted perspective view showing a structure of a liquid crystal display element according to the present invention, and FIG. 2 is a sectional view thereof. 1 and 2, for simplification of description, various wirings such as scanning wirings, signal wirings, auxiliary capacitance lines, and TFTs (Thin Film Transistor) other than the main part of the present invention are shown.
r) Illustration of details such as switching elements is omitted.

This liquid crystal display device comprises a first liquid crystal cell 10
1 and a second liquid crystal cell 103 arranged so as to be superposed thereon.
And polarizing plates 105, 107, 109 and 111 attached above and below the liquid crystal cells 101 and 103, respectively,
A first drive circuit (not shown) that applies a drive voltage of a first waveform to the first liquid crystal cell 101, and a drive voltage of a second waveform different from the drive voltage of the first waveform And a second drive circuit (not shown) for applying the drive voltage of the waveform in synchronization with the frame period.

The first liquid crystal cell 101 has a pixel electrode 113.
And a TFT (not shown) for switching the voltage application to the pixel electrode 113, and an alignment film 115 that covers the surface of the substrate including these TFT array substrate 11
7 and a counter electrode 119 arranged to face the pixel electrode 113.
And the counter substrate 1 on which the alignment film 121 covering the same is formed.
23, the TFT array substrate 117, and the counter substrate 123 are opposed to each other through a spacer 125, and the space between them is sealed with a sealing material 127, and the empty cells formed thereby are sealed. Liquid crystal layer 129 sandwiched
The main part is composed of the
5, 107 are attached.

The second liquid crystal cell 103 has substantially the same structure as the first liquid crystal cell 101 described above, and has a pixel electrode 131 and a TFT (not shown) for switching voltage application to the pixel electrode 131. ), A TFT array substrate 135 on which an alignment film 133 covering the surface of the substrate is formed, a counter electrode 137 opposed to the pixel electrode 131, and a counter electrode 139 covering the counter electrode 137. Substrate 141, TFT array substrate 135, and counter substrate 1
41 and a liquid crystal layer 147, which is sealed and sandwiched in an empty cell formed by sealing with a sealing material 145 in the gap (cell gap) between the substrates, which are opposed to each other via a spacer 143. The polarizing plate 109, 111 is attached on the upper and lower sides of the section. And this second
The liquid crystal cell 103 of 1 is the same as that of the first liquid crystal cell 101.
The pixels are arranged to be shifted by 1/4 in length and width (about 150 μm) with respect to the pixel of the first liquid crystal cell 101 so that 1/4 portion of each of 4 adjacent pixels overlaps each other. .

A first drive circuit (not shown) is electrically connected to the first liquid crystal cell 101 so as to apply a drive voltage having a first waveform to the first liquid crystal cell 101. The second drive circuit (not shown) applies a second drive voltage of the second waveform to the second liquid crystal cell 103 in synchronization with the frame period of the first waveform.
Is electrically connected to the liquid crystal cell 103.

For each of the pixel electrodes 113 and 131, an ITO (indium tin oxide) film is used as a transparent conductive film,
It is formed as a pixel electrode having a pixel size of about 300 μm in length and width. In addition, the first liquid crystal cell 101 and the second liquid crystal cell 103 are formed by the arranged pixel electrodes 113 and 131.
The display area of the screen formed in each is 150m in height.
The size is m x width 250 mm, and the number of pixels is about 400,000.

Further, as the liquid crystal layers 129 and 147, STN is used.
A liquid crystal composition obtained by adding a chiral agent to a (Super Twisted Nematic) type liquid crystal was used. The liquid crystal layers 129 and 147
The molecular axis of is about 2 between the upper and lower substrates due to the action of the chiral agent.
The alignment film 11 is twisted and arranged at a twist angle of 10 degrees.
5, 121, 133, and 139 were subjected to rubbing orientation treatment, and no voltage was applied to each substrate surface by 4-5.
The orientation is maintained in a substantially constant azimuth with a pretilt angle of about several degrees.

As described above, in the liquid crystal display element of the present invention, one pixel of the first liquid crystal cell 101 overlaps with each one-fourth pixel size of each of the four adjacent pixels of the second liquid crystal cell 103. It is arranged. As a result, the liquid crystal display element according to the present invention has a pixel size (area of 1 pixel) of one pixel is 1/4 of that of a liquid crystal display element having a conventional structure using only one of the liquid crystal cells. 150 μm x 1
The size can be reduced to 50 μm, and the number of pixels is about four times
The number of pixels is 1.6 million, and the size of the pixel electrodes 113 and 131 inside the first liquid crystal cell and the second liquid crystal cell is the same as that of the conventional liquid crystal display element. And high density.

When each of the first liquid crystal cell 101 and the second liquid crystal cell 103 performs 16 gradation display, the maximum number of displayable gradations of the liquid crystal display element according to the present invention is 16.
× 16 = 256 gradations can be realized. At this time the first
It goes without saying that the sizes of the pixel electrodes 113 and 131 inside the liquid crystal cell 101 and the second liquid crystal cell 103 may be the same as those of the conventional liquid crystal display element.

Further, the twist of the molecular axis of the liquid crystal layer 129 of the first liquid crystal cell 101 and the twist of the molecular axis of the liquid crystal layer 147 of the second liquid crystal cell 103 are made opposite to each other, whereby total transmission is achieved. Since it is possible to obtain the so-called color correction effect of eliminating the coloring of the image in the state (white mode), it can be said that it is suitable, for example, in the case of performing full-color display together with a color filter.

By the way, by making the drive voltage applied to the first liquid crystal cell 101 and the drive voltage applied to the second liquid crystal cell 103 have different waveforms in synchronization with each frame cycle, The liquid crystal cell 101 and the second liquid crystal cell 103 are individually driven to drive these liquid crystal cells 1
The display state of each apparently subdivided pixel is controlled by the combination of 01 and 103 display states. Conversely speaking, the waveform of the first drive voltage and the waveform of the second drive voltage having such waveforms that can control the display state of each apparently subdivided pixel are generated. Needless to say, the first drive circuit and the second drive circuit are formed in advance. When pixel display data is input from the outside to each of the first drive circuit and the second drive circuit set in this way, according to the above-described embodiment, the first drive circuit and the second drive circuit are input. The drive circuit generates the first waveform and the second waveform corresponding to the display state of each pixel for 1.6 million pixels in synchronization with the frame period as a reference, and respectively generates the first liquid crystal cell 101 and the second liquid crystal. The first liquid crystal cell 10 is applied individually to the cell 103.
The first and second liquid crystal cells 103 are individually driven in synchronization with each other.

In the above embodiment, the first liquid crystal cell 1
The pixel size of 1 pixel of 01 and 1 of the second liquid crystal cell 103
The pixel size of the pixel is the same, and the first liquid crystal cell 101 and the second liquid crystal cell 103 are connected to each other by the pixel electrode 1
Although the overlaps of 13 and 131 are arranged so as to be shifted by 1/4 pixel, the present invention is not limited to this. For example, the first
Pixel size of 1 pixel of the liquid crystal cell of 1 and 1 of the second liquid crystal cell
It is also possible to make the pixel size different from the pixel size and to arrange, for example, two pixels of the second liquid crystal cell to overlap one pixel of the first liquid crystal cell. In such a case, the pixel size of the second liquid crystal cell is preferably 10 times or less to 1/10 or more of the pixel size of the first liquid crystal cell.

Further, in the above embodiment, the case of the active matrix type liquid crystal display element using the switching element such as the TFT and the STN type liquid crystal is exemplified, but the present invention is not limited to this. In addition to this, it goes without saying that the technique of the present invention can be applied to an active matrix type liquid crystal display element using a so-called TN type liquid crystal having a twist angle of about 90 degrees, a simple matrix liquid crystal display element and the like. Further, it goes without saying that the present invention can be applied not only to the nematic liquid crystal as described above, but also to other liquid crystal display devices using, for example, a ferroelectric liquid crystal or a liquid crystal of the dynamic scattering effect. Yes.

In addition, it goes without saying that various changes can be made to the material for forming each part of the liquid crystal display device of the present invention without departing from the scope of the present invention.

[0025]

As is clear from the detailed description above, according to the present invention, the structure is such that the manufacturing method can be performed without making the manufacturing method complicated and difficult, and the pixel definition and density can be increased. It is possible to provide a liquid crystal display device that realizes the above.

[Brief description of drawings]

FIG. 1 is a partially omitted perspective view showing a structure of a liquid crystal display element according to the present invention.

FIG. 2 is a sectional view showing a structure of a liquid crystal display element according to the present invention.

FIG. 3 is a sectional view showing a structure of a conventional liquid crystal display element.

[Explanation of symbols]

101 ... First liquid crystal cell, 103 ... Second liquid crystal cell, 1
05, 107, 109, 111 ... Polarizing plates, 113, 13
1 ... Pixel electrodes, 115, 121, 133, 139 ... Alignment films 117, 135 ... TFT array substrates 119, 13
7 ... Counter electrode, 123, 141 ... Counter substrate, 125, 1
43 ... Spacers, 127, 145 ... Sealing materials, 129, 1
47 ... Liquid crystal layer

Claims (1)

[Claims] 1. A first substrate on which a first electrode is formed, a second substrate on which a second electrode is arranged facing the first electrode, the first substrate and the second substrate. A first liquid crystal cell having a first liquid crystal layer sealed and sandwiched between the first liquid crystal cell and the first substrate, and a first waveform of the first corrugated electrode on the first electrode and the second electrode of the first liquid crystal cell. A first drive circuit for applying a drive voltage, a third substrate on which a third electrode is formed, a fourth substrate on which a fourth electrode is formed facing the third electrode, And a second liquid crystal layer enclosed and sandwiched between the third substrate and the fourth substrate, and arranged so that at least a part of a plurality of pixels overlaps one pixel of the first liquid crystal cell. Applied to the first liquid crystal cell to the third electrode and the fourth electrode of the second liquid crystal cell. A second drive circuit for applying a drive voltage of a second waveform different from the drive voltage of the first waveform according to a frame cycle of the drive voltage of the first waveform. Liquid crystal display device.