JPH07270813A - Liquid crystal display device and information transferring device provided with the same - Google Patents

Abstract

PURPOSE:To display multi-levels by allowing prescribed plural sub-pixels to light with various patterns and also prevent the generation of a pseudo outline and the complication of the constitution of a circuit impressing signals. CONSTITUTION:At the time of a multi-level display, a same signal is impressed to two lines of electrodes Ca, Cc by allowing scanning electrodes Ca, Cc to be conducted with a conductive part 45. Thus, a circuit impressing signals to scanning electrodes Ca,... is simplified by the amount being conducted. In other words, the number of sub-pixels constituting pixels performing the multi- level display can be increased with a margin by the amount by which the circuit is simplified. Consequently, since parts of a white display can be arranged while being disparsed symmetrically in the up-and-down direction and to the center line by increasing the number of sub-pixels, the generation of the pseudo outline is prevented even though multi-levels are made different.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to a liquid crystal display device which displays a plurality of gray levels by lighting a predetermined plurality of subpixels in various patterns.

[0002]

2. Description of the Related Art Conventionally, various methods have been proposed for expressing multi-tone in a liquid crystal display device. An example is a method of controlling the applied voltage to each pixel according to an applied voltage-transmittance curve to obtain a desired level of brightness. One frame is divided into several subframes, and ON / OFF is time-modulated. By doing so, there is a method of performing multi-tone display. However, in the above method, since the applied voltage-transmittance curve is very steep, the brightness greatly changes even by a small error in the applied voltage, and it is difficult to accurately output the desired level of brightness. It was Further, in the above method, there is a problem that the circuit becomes complicated and the load on the display device and the peripheral circuits becomes large because high-speed scanning is required from the viewpoint of suppressing flicker.

By the way, as another method, there is a method in which several pixels (sub-pixels) are set as one set and a plurality of pixels (sub-pixels) are lit in various patterns to display multi-tone.

Here, the above-mentioned specific example and its features will be described with reference to FIGS. 1 (a) and 1 (b) and FIG. It should be noted that each of the specific examples is for performing multi-tone display of 16 levels.

In the specific example shown in FIGS. 1A and 1B, four pixels (sub-pixels) are set as one set, and a pixel capable of multi-tone display is formed by these four sub-pixels. And
To obtain a linear optical level of 16 levels from 0 to 15, the area ratio of these sub-pixels is 8: 4: 2: 1,
The combination of driven sub-pixels is changed.
It should be noted that the difference between FIGS. 1A and 1B is only the arrangement of the four sub-pixels. Also, for example, the sub-pixel shown in FIG. 1A is formed by the intersection of four scanning electrodes and one information electrode. However, in order to make the area of the sub-pixel as described above, The width is set to be 8: 4: 2: 1. Here, these electrodes are formed on a pair of substrates arranged so as to face each other, as is known. By the way, generally, the area ratio of the sub-pixels is set to 2 ⁿ : 2
^A linear optical level can be obtained by setting ^n-1 : ...: 2 ¹ : 2 ⁰ . Further, in order to obtain a more natural image in this method, image processing such as a dither method or an error diffusion / average density method is used together.

By the way, when the number of sub-pixels is as small as 4 as described above, a peculiar pattern called "pseudo contour" occurs when a natural image such as a photograph is displayed, and the image quality is significantly deteriorated. There was a problem.

That is, for example, when a level 7 gradation is displayed using the pixels shown in FIG. 1A, the upper side of each pixel is displayed in white as shown in the portion of FIG. 3I. , When the gradation of level 7.5 is displayed, the diagonally diagonal part is displayed in white as shown in the part of FIG. 3 (II). Further, when the gradation of level 8 is displayed, the lower side of each pixel is displayed in white, contrary to the case of level 7. Therefore, when considering the center of the ON region (white display portion), it is located above the pixel at level 7, at approximately the center of the pixel at level 7.5, and at the bottom at level 8. As a result, when a natural image such as a photograph is displayed and the actual contour of the image changes from level 7 to level 8, in the liquid crystal display device, the ON area is changed due to the difference in gradation. The center of (white part) is shifted, and the contour is different from the actual contour (pseudo contour).
Therefore, there is a problem in that the image quality remarkably deteriorates due to the deviation of the contour. Normal pixel pitch is a few
Although it is about 00 μm, the deviation of the contour is recognized very clearly even at such a pixel pitch, and a problem of pseudo contour occurs.

[0008]

DISCLOSURE OF THE INVENTION The present inventors
A display device having a structure as shown in FIG. 2 was produced. That is,
By setting nine pixels (sub-pixels) having an area ratio as shown in FIG. 2 as one set, and driving these sub-pixels in an appropriate combination, as shown in FIG. It is arranged to be arranged vertically symmetrically (or horizontally symmetrically). Therefore, in any gradation, the center of the ON region (white display portion) is located at the center of the pixel and does not change, and it is possible to prevent the occurrence of the pseudo contour as described above.

By the way, in the method shown in FIG. 2, the pseudo contour is prevented from occurring by increasing the number of sub-pixels.
Since the number of electrodes that have to be driven is increased, the configuration of a circuit for applying a signal may be complicated and enormous correspondingly.

Therefore, according to the present invention, a plurality of electrodes, which are formed on the same substrate and constitute the same pixel, are made conductive, and the same signal is applied to the plurality of electrodes to generate a pseudo contour, and An object of the present invention is to provide a liquid crystal display device that prevents the configuration of a circuit for applying a signal from becoming complicated, and an information transmission device including the liquid crystal display device.

[0011]

The present invention has been made in view of the above circumstances, and a liquid crystal display device according to the first invention comprises a pair of substrates arranged to face each other,
A pair of electrode groups respectively formed on the pair of substrates and forming a large number of sub-pixels at intersections, and a predetermined plurality of sub-pixels constitutes one pixel, and the predetermined plurality of sub-pixels. In a liquid crystal display device in which pixels are lit in various patterns to display multi-tone, a plurality of electrodes which are formed on the same substrate and constitute the same pixel are electrically connected, and the same signal is applied to these electrodes. It is characterized in that it is applied.

The information transmission device according to the second invention is
A logic control circuit for outputting a drive control signal; a scanning line drive circuit for outputting scanning line address data and a scanning method signal; an information line drive circuit for outputting display data and a scanning method signal; and the liquid crystal display device. It is characterized by having.

[0013]

According to the above construction, by applying the same signal to the plurality of electrodes which are conducted, multi-tone display is possible, and a circuit for applying a signal is provided by the amount of conduction of the electrodes. Easy to configure.

[0014]

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

First, the liquid crystal display device 1 according to this embodiment will be described with reference to FIGS. 5 and 6.

The liquid crystal display device 1 is provided with a pair of scanning electrode substrate 2 and information electrode substrate 3 which are arranged so as to face each other with a predetermined gap therebetween, and a scanning electrode group is provided on each substrate 2 and 3. C and the information electrode group I are formed respectively. Here, the scan electrode group C includes the strip-shaped scan electrodes Ca and C.
b, Cc, ... are arranged side by side, and the other information electrode group I also has band-shaped information electrodes Ia, Ib, I.
A large number of c, ... Are arranged side by side.

By the way, in this embodiment, as shown in FIG. 2, nine sub-pixels are set as one set, and 16 gradations can be displayed by these sub-pixels. That is, the scanning electrodes Ca, Cb, Cc, ... Are not uniform in electrode width, as shown in detail in FIG.
The width ratios of three adjacent scan electrodes Ca, Cb, Cc are set to be 2: 1: 2. On the other hand, the information electrodes Ia, Ib, Ic, ... Have a uniform width (the ratio of the electrode widths of the three information electrodes Ia, Ib, Ic is 1: 1 :).
It is set to be 1). The pair of electrode groups C and I have a large number of pixels (hereinafter,
“Sub-pixel”) is formed, and three scan electrodes C are formed.
The sub-pixels a, Cb, Cc and the three information electrodes Ia, Ib, Ic constitute nine sub-pixels as shown in FIG.

Each end of the information electrodes Ia and Ic is electrically short-circuited (conducted) by the conducting portion 46, and each end of the scanning electrodes Ca and Cc is electrically short-circuited by the conducting portion 45. There is. Then, these information electrodes Ia, Ic
The same signal is applied to the scanning electrodes Ca and Cc, respectively, so that 16 gradations as shown in FIG. 4 are displayed. The display state of the nine sub-pixels is as shown in FIG.
As shown in, since it is vertically symmetrical and horizontally symmetrical,
Even if the information electrodes Ia and Ic and the scanning electrodes Ca and Cc are short-circuited, 16 levels of gradation can be displayed without any problem.

Next, peripheral devices of the liquid crystal display device 1 according to this embodiment will be briefly described with reference to FIG.

A scanning line drive circuit 402 and an information line drive circuit 403 are connected to the liquid crystal display element 1 according to this embodiment, and a drive voltage generation circuit 405 and a logic control circuit 406 are connected to these circuits 402 and 403. Are connected respectively. In addition, the logic control circuit 406 includes
A data generator 407 having a video RAM (VRAM) is connected. Then, the data from the data generator 407 is converted into a scan line drive control signal and an information line drive control signal (image signal) by the logic control circuit 406, and the respective signals are supplied to the scan line drive circuit 402 and the information line drive circuit. It is configured to be applied to 403.

Next, the effect of this embodiment will be described.

According to the present embodiment, the display state of 16 gradations is as shown in FIG. 4, and the center of the ON area (white display portion) is constant and does not change in any gradation. The occurrence of false contours as described is prevented. In addition, in this embodiment, one subpixel is formed by nine subpixels.
Although the number of electrodes that must be driven is increased by configuring two multi-gradation display pixels, since a part of the electrodes is short-circuited (conducted) as described above, the final output stage number of the drive circuit is 2 / It can be reduced to 3. On the contrary,
If the short circuit is not performed, the drive circuit becomes enormous and complicated, and the device becomes expensive.

In the liquid crystal display device shown in FIG. 5, 15 scanning electrodes and 18 information electrodes are provided.
Although 5 × 18 sub-pixels are formed and 5 × 6 pixels are formed, it is not limited to this. For reference, the present inventor prototyped a device having 400 × 640 pixels.

Next, an embodiment for color display will be described with reference to FIGS. The same parts as those shown in FIG. 5 are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the scanning electrode group C1 has the same shape as that of the above-described embodiment, but the information electrode group I1 is used.
Is configured by alternately arranging wide information electrodes Iw and narrow information electrodes In. The pair of electrode groups C1 and I1 form a large number of sub-pixels at the intersections, and are formed by three scanning electrodes Ca, Cb and Cc and two information electrodes Iw and In. Two sub-pixels
Pixels that perform R, G, or B monochromatic color display are configured (see FIGS. 7B and 8). It should be noted that the pixels that perform the single color display are displayed in multiple gradations, as shown in FIG. Pixels for multicolor display are formed by grouping three pixels for single color display.

Further, the respective ends of the scan electrodes Ca and Cc are electrically short-circuited by the conducting portion 45, and the same signal is applied as in the above-mentioned embodiment. As shown in FIG. 9, since the display states of the six sub-pixels are vertically symmetrical, 16-level gradation can be displayed without any problem even if the scan electrodes Ca and Cc are short-circuited.

Therefore, also in this embodiment, as in the above-described embodiments, the ON regions (white display portions) are vertically symmetrically arranged in any gradation, so that the pseudo contour as described in the above-mentioned conventional example is arranged. Is prevented from occurring. Regarding the left-right direction, the ON region (white display part) is not symmetrical, but since the width ratio of the information electrodes Iw and In is 2: 1, the ON region (white display part) shifts in the left-right direction. Is small and the influence of the pseudo contour is small. In addition, in the present embodiment, three scanning electrodes Ca, Cb, and Cc constitute one multi-tone display pixel, and although the number of electrodes that must be driven increases, a part of the electrodes as described above. , The final output stage number of the drive circuit can be reduced to 2/3. Then, in this way, when one pixel has 4096 colors, and image processing such as a dither method is added, a substantially larger number of colors are expressed, and a good image is obtained.

Although FIG. 7 shows 5 × 6 color display pixels, the number of color display pixels is not limited to this. For reference, the present inventor prototyped a device having 400 × 640 pixels.

[0029]

As described above, according to the present invention,
Since a plurality of electrodes which are formed on the same substrate and constitute the same pixel are made conductive, and the same signal is applied to the plurality of electrodes, the electrodes are made conductive,
The configuration of a circuit for applying a signal can be simplified. In addition, since the configuration of the circuit for applying the signal is simple,
It is possible to increase the number of sub-pixels that constitute the multi-tone display pixel, and therefore it is possible to disperse the white display portion and prevent pseudo contours from occurring.

[Brief description of drawings]

FIG. 1 is a schematic diagram for explaining a method of displaying multiple gradations with four subpixels as one set, and FIGS. 1A and 1B are diagrams showing two examples in which the arrangement of subpixels is different.

FIG. 2 is a schematic diagram for explaining a method of displaying multiple gradations with nine subpixels as one set.

FIG. 3 is a diagram for explaining a problem when displaying multiple gradations by the pixel of FIG. 1 (a).

FIG. 4 is a diagram for explaining a display state of the pixel of FIG.

5A is a view for explaining the structure of the liquid crystal display device according to the first embodiment, and FIG. 5B is a detailed view thereof.

FIG. 6 is a diagram for explaining peripheral devices of the liquid crystal display device according to the present embodiment.

7A is a diagram for explaining the structure of the liquid crystal display device according to the second embodiment, and FIG. 7B is a detailed diagram thereof.

FIG. 8 is a schematic diagram for explaining the arrangement of sub-pixels in the second embodiment.

FIG. 9 is a schematic diagram showing a display state of a liquid crystal display device according to a second example.

[Explanation of symbols]

 1 liquid crystal display device 2 substrate (scan electrode substrate) 3 substrate (information electrode substrate) 402 scan line drive circuit 403 information line drive circuit 406 logic control circuit C electrode group (scan electrode group) C1 electrode group (scan electrode group) I electrode Group (information electrode group) I1 electrode group (information electrode group)

Claims (2)

[Claims] 1. A predetermined number of substrates are provided, comprising a pair of substrates arranged to face each other, and a pair of electrodes formed on the pair of substrates to form a large number of sub-pixels at intersections. And one sub-pixel of
In a liquid crystal display device for displaying a plurality of gradations by lighting a plurality of predetermined sub-pixels in various patterns, a plurality of electrodes which are formed on the same substrate and constitute the same pixel are made conductive, A liquid crystal display device characterized in that the same signal is applied to both. 2. A logic control circuit which outputs a drive control signal, a scan line drive circuit which outputs scan line address data and a scan method signal, and an information line drive circuit which outputs display data and a scan method signal. 1. A liquid crystal display device according to 1, and an information transmission device comprising: