JPH06161395A - Method for displaying background of active matrix type color display - Google Patents

Abstract

PURPOSE:To make bright point defects of specially conspicuous green and red colors nonactual by specifying a display color for a background area. CONSTITUTION:The active matrix type color display 1 has bright point defective pixels with some statistical probability and green defective pixels GP are included. Then green is specified as the display color of the background area 3 so as to make the specially remarkable green defective pixels GP nonactual. In concrete, the video signal supplied from a video signal source 5 connected to the color display 1 is controlled. This video signal source 5 consists of a computer, etc., and the video signal is controlled through software to set the display color of the background area to green. Namely, a green signal component DG of the video signal distributed to the background area 3 is set to a low level below a threshold voltage and a red signal component DR and a blue signal component DB are set to a high level above the threshold voltage. Then only green pixels illuminate in normally white mode and a uniform green background color is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a background display method for an active matrix type color display. More specifically, the present invention relates to a background display method for making a bright spot defective pixel invisible on a color graphic display of a computer or a display of a game machine.

[0002]

2. Description of the Related Art In order to facilitate understanding of the present invention, first, a general structure of an active matrix type liquid crystal color display will be briefly described with reference to FIG. In addition,
The present invention is not limited to liquid crystal color displays, but also covers color displays using other electro-optical materials. As shown in the figure, the liquid crystal 1 is provided between the drive substrate 101 and the counter substrate 102, which are bonded together with a predetermined gap.
03 is filled. Scanning lines 104 and signal lines 105 that are orthogonal to each other are provided on the inner surface of the drive substrate 101. Pixel electrodes 106 and thin film transistors (TFTs) 107 are arranged in a matrix at each intersection to define individual pixels. Further, although not shown, a liquid crystal alignment film is also formed on the inner surface of the drive substrate 101. On the other hand, the counter substrate 1
A counter electrode 108 and a color filter layer 109 are formed on the inner surface of 02. The color filter layer 109 has segments of three primary colors of red (R), green (G), and blue (B) and is aligned with each pixel electrode 106 to form three types of color pixels. Although not shown, a liquid crystal alignment film is also provided on the surface of the counter electrode 108. Further, polarizing plates 110 and 111 are attached to the outer surfaces of the drive substrate 101 and the counter substrate 102, which are adhered to each other. The TFT 107 is selected via the scanning line 104, and a video signal is written to the pixel electrode 106 via the signal line 105. A voltage is generated between the pixel electrode 106 and the counter electrode 108, and the liquid crystal 103 rises. This is a pair of crossed Nicols arranged polarizing plates 11
When 0, 111, the white incident light is transmitted as a change in transmission amount, and color display is performed.

FIG. 6 is a schematic view showing one pixel of an active matrix type liquid crystal color display cut out. The left side shows a state in which no voltage is applied, and the right side shows a state in which voltage is applied. The polarization axis a of the upper polarizing plate 111 and the polarization axis b of the lower polarizing plate 110 are orthogonal to each other. Further, the alignment direction of the upper alignment film 112 and the alignment direction of the lower alignment film 113 are also orthogonal to each other. Therefore, the liquid crystal 103 has a twist orientation twisted by 90 °. When no voltage is applied, the linearly polarized light component of the incident light that has passed through the upper polarizing plate 111 is rotated by 90 ° by the twist-aligned liquid crystal 103 and passes through the lower polarizing plate 110. Therefore, white display is obtained when no voltage is applied. On the other hand, when a voltage is applied, the liquid crystal 103
Rises and the optical rotation is lost. Therefore, the linearly polarized component of the incident light is blocked by the lower polarizing plate 110, and black display is obtained. Hereinafter, such a display system is referred to as a normally white mode.

FIG. 7 is a graph showing the relationship between the pixel transmittance and the applied voltage when the active matrix liquid crystal color display is driven in the normally white mode. In the normally white mode, the pixel transmittance reaches 100% with no voltage applied, and the applied voltage is, for example, 5%.
When it is raised to V or higher, the transmittance becomes 0%. If the applied voltage is set to an intermediate level, it is possible to obtain a desired gradation display. As described with reference to FIG. 5, the voltage applied to the pixel via the conductive TFT is maintained as it is until the next selection timing after the TFT is brought into the non-conductive state. However, when the TFT has a current leakage failure or the like, the holding voltage of the pixel is gradually decreased, the transmittance is increased, and a so-called bright spot defect occurs.

[0005]

FIG. 8 shows a display screen 11 of an active matrix type liquid crystal color display 100.
It is a schematic diagram which shows 5. When the color display is used for computer graphic display or game console image display, the entire screen 115 is occupied by the background area 116 in the standby state. Also, when displaying a message such as characters or characters, most of the screen is occupied by the background area. Conventionally, black or gray has been generally used as the display color of the background area 116. When driving in the normally white mode, a desired black display can be obtained by applying a voltage to all of the RGB three primary color pixels. Alternatively, a desired gray display color can be obtained by applying an intermediate level voltage.
By the way, in general, due to variations in the manufacturing process,
Active matrix liquid crystal color display 100
There is a probability that a bright spot defective pixel is inherently present in the pixel. If the bright spot defective pixels 117 are scattered in the black background region 116, the display quality is remarkably impaired, so that the defective products are conventionally discarded as defective products, which causes a reduction in manufacturing yield.
As shown in the figure, red (R), green (G), and blue (B) bright spot defective pixels occur with a certain statistical probability. Among these, the green bright spots are particularly conspicuous due to the visibility, and are a fatal defect. Also, red bright spots are the next most visible, and blue bright spots are not so noticeable. In this way, since the saliency differs depending on the hue, the actual number of defective pixels is set for each of the three primary colors. For example, in order to facilitate understanding, only one green bright spot defect is allowed, two red bright spot defects are allowed, and three blue bright spot defects are allowed. And In this case, the occurrence of the green bright spot defect is particularly fatal and significantly lowers the manufacturing yield. However, no effective means has conventionally been taken to remedy such a bright spot defect, which has been a problem to be solved in terms of manufacturing yield and manufacturing cost.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention relieves an active matrix type color display having bright spot defective pixels at the actual use stage and substantially improves the manufacturing yield. The purpose is to do.
The following measures have been taken in order to achieve this object. That is,
When a screen including a background area is displayed in a normally white mode on an active matrix type color display including a plurality of types of color pixels, the relatively conspicuous intrinsic bright point defects of the color pixels are made relatively invisible. Therefore, the background area is specified as a specific display color.

[0007]

As described above, the bright spot defect of the green pixel is particularly remarkable from the viewpoint of the visibility. In order to selectively make this non-visible, the background area is designated as the green display color. The green bright spots are buried in the green background and become completely inconspicuous. Specifically, among the video signals distributed to the background area, the green signal component may be set below the threshold level, and the remaining red signal component and blue signal component may be set above the threshold level. In the normally white mode, only the green pixels are turned on and a uniform green background area is obtained. In addition to the green pixels, the bright spot defect of the next most prominent red pixel also becomes invisible at the same time, so the background area may be designated as an additive mixed color display color of green and red (that is, a yellow display color).
In this case, the green bright spots and the red bright spots are scattered on the yellow background, but they can be relatively invisible compared to the black background. Alternatively, the background area can be designated as a red display color in order to effectively make the bright spot defect of the red pixel non-visible.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic diagram showing a first embodiment of a background display method for an active matrix color display according to the present invention. As shown in the figure, the active matrix color display 1 is intended for the liquid crystal electro-optical material shown in FIG. 5, for example. However, the present invention is not limited to this, and a display using another electro-optical material may be used. This color display 1 is driven in a normally white mode, for example, a color graphic display of a computer,
Used for displaying images on game consoles. The screen 2 in the standby state of the computer or the game machine is entirely occupied by the background area 3. Alternatively, when the message area 4 such as characters and characters is included, most of the rest of the screen 2 is the background area 3.
Occupied by.

The active matrix type color display 1 includes bright spot defective pixels with a certain statistical probability.
The green defective pixel GP is included in this. The present embodiment is characterized in that the display color of the background area 3 is designated as green in order to make this particularly prominent green defective pixel GP non-visible. Specifically, the video signal supplied from the video signal source 5 connected to the color display 1 is controlled. The video signal source 5 comprises a computer or the like, and controls the video signal by software to set the display color of the background area to green.
That is, of the video signals distributed to the background area 3, the green signal component DG is set to a low level equal to or lower than the threshold voltage, and the red signal component DR and the blue signal component DB are set to a high level equal to or higher than the threshold. In the normally white mode, only the green pixels are lit and a uniform green background is obtained. Therefore, the green bright spot defective pixel GP is buried in the background region 3 and cannot be distinguished at all. In the present embodiment, it is possible to remarkably improve the manufacturing yield of the active matrix type color display by actually relieving the green bright spot defect having a strict tolerance limit.

FIG. 2 is a schematic view showing a second embodiment of the background display method of the active matrix type color display according to the present invention. The basic principle is the first shown in FIG.
Similar to the embodiment, corresponding parts are provided with corresponding reference numerals and reference symbols to facilitate understanding. The difference from the first embodiment is that the background area 3 is designated as an additive mixed color display color of green and red. As described above, in addition to the green defective pixel GP, the screen defect 2 may include the next remarkable red defective pixel RP. In the present embodiment, bright spot defects of red pixels in addition to green pixels are not visible. When the background area 3 is displayed in an additive color mixture of green and red, the background area 3 is yellow as a whole. The green bright spot defective pixel GP on the yellow background is
Obviously less noticeable than on a black background. Similarly, the red bright spot defective pixel RP on the yellow background is less noticeable than the black background. Therefore, the manufacturing range of the color display 1 is relatively improved because the allowable range for the bright spot defective pixel is widened. In order to display a mixed color of red and green, among the video signals distributed from the video signal source 5 to the background area 3, the green signal component DG and the red signal component DR are set to a low level and the blue signal component is set. DB should be set to a high level.

FIG. 3 is a schematic view showing a third embodiment of the background display method of the active matrix type color display according to the present invention. The basic principle is the first shown in FIG.
Similar to the embodiment, corresponding parts are provided with corresponding reference numerals and reference symbols to facilitate understanding. In this example, in particular, the background region 3 is designated as a red display color in order to effectively make the red bright spot defective pixel RP non-visible. Specifically, among the video signals distributed from the video signal source 5 to the background area 3, only the red signal component DR is set to low level, and the remaining green signal component DG and blue signal component DB are set to high level. . In general, bright spot defects are noticeable on a static screen,
This is especially noticeable when most of the screen is occupied by a uniform background area. On the other hand, when displaying a moving image, the bright spot defect is not so noticeable. In view of this point, the present invention is characterized in that the bright spot defects are practically made invisible at the use stage according to the application of the active matrix type color display. In a computer color graphic display or a color display of a game machine that appropriately displays a still screen, it is easy to specify the display color of the background area by means of software.

FIG. 4 is a block diagram showing a structural example of an active matrix type liquid crystal color display driven according to the present invention. As shown in the drawing, liquid crystal color pixels LC of three types of RGB are arranged in a matrix. An additional capacitance CS is connected in parallel to each liquid crystal pixel LC. In order to drive each liquid crystal pixel LC, a corresponding thin film transistor TFT is provided. The gate electrode of each TFT is connected to the scanning line 51, the source electrode is connected to the signal line 52, and the drain electrode is connected to the pixel electrode located at one end of the corresponding liquid crystal pixel LC. The other end of each liquid crystal pixel LC is connected to a common counter electrode COM.

A plurality of scanning lines 51 are provided in the vertical shift register 5
3 are connected and selected line by line. On the other hand, the plurality of signal lines 52 are connected to any of the three input lines via the corresponding sampling switches SW. For example, the first signal line counting from the left end is connected to the first input line 54 and receives the supply of the red signal component DR of the video signal. The second signal line is connected to the second input line 55 and receives the green signal component DG. The third signal line is connected to the third input line 56 and receives the blue signal component DB. Hereinafter, this sequence is repeated. A horizontal shift register 58 is connected to each sampling switch SW via a gate circuit 57. The horizontal shift register 58 sequentially makes the sampling switches SW selectively conductive via the gate circuit 57.

Next, the operation of the active matrix type liquid crystal color display shown in FIG. 4 will be described. The vertical shift register 53 selects the scanning lines 51 line by line. The transistor TFT arranged on the selected scanning line becomes conductive. The horizontal shift register 58 sequentially opens the sampling switch SW, samples the video signal from each of the input lines 54 to 56, and supplies it to the corresponding signal line.
The supplied video signal is a transistor TF in a conductive state.
It is written in the liquid crystal pixel LC via T. When the selection of the scanning line is released, the transistor TFT becomes non-conductive, and the video signal written in the liquid crystal pixel LC is held until the next selection timing. When a video signal having the same potential as that of the counter electrode COM is written, the liquid crystal pixel is in a light transmitting state. On the contrary, when a video signal having a potential difference of ± 5 V with respect to the potential of the counter electrode is written, the liquid crystal pixel is in a light blocking state, and normally white mode driving is performed. At this time, if the amplitude of the green signal component DG of the video signal is set to 0 V with respect to the counter electrode potential and the amplitudes of the remaining red signal component DR and blue signal component DB are set to ± 5 V, the background region of the green display color is set. Is obtained. Such potential setting of each signal component is performed by software by a computer. In the present invention, the background display color is forcibly designated and the bright spot defect is made non-visible when no image information is given.

[0015]

As described above, according to the present invention, by designating the background region as a specific display color, the conspicuous green and red bright spot defects are made non-visible, and are conventionally discarded as defective products. The active matrix color display panel is relieved as a good product. As a result, the manufacturing yield is improved and the cost can be reduced. The color display panel relieved by the means of designating the display color of the background area can be used in a sufficiently wide range such as a color graphic display of a computer or an image display of a game machine.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a first embodiment of a background display method of an active matrix type color display according to the present invention.

FIG. 2 is a schematic diagram showing a second embodiment of the same.

FIG. 3 is a schematic view showing a third embodiment of the same.

FIG. 4 is a circuit diagram showing a specific configuration example of an active matrix type color display driven according to the present invention.

FIG. 5 is a schematic perspective view showing a conventional general active matrix liquid crystal color display.

FIG. 6 is a schematic diagram for explaining normally white mode driving of an active matrix type color display.

FIG. 7 is a graph showing the relationship between pixel transmittance and applied voltage of an active matrix liquid crystal color display.

FIG. 8 is a schematic diagram showing a background display method of a conventional active matrix color display.

[Explanation of symbols]

 1 active matrix color display 2 screen 3 background area 4 message area 5 video signal source GP green bright spot defective pixel RP red bright spot defective pixel

Claims (4)

[Claims] 1. When a screen including a background area is displayed in a normally white mode on an active matrix type color display including a plurality of types of color pixels, a relatively significant luminescent spot defect of the color pixels inherent therein is relatively caused. To become non-existent,
A background display method for an active matrix type color display, characterized in that the background area is designated as a specific display color. 2. The background display method for an active matrix color display according to claim 1, wherein the background area is designated as a green display color in order to make the bright spot defect of the green pixel invisible in particular. 3. The active matrix color display according to claim 1, wherein the background area is designated as an additive color mixture display color of green and red in order to make the bright spot defects of the green pixel and the red pixel non-visible. Background display method. 4. The background display method for an active matrix color display according to claim 1, wherein the background area is designated as a red display color in order to effectively make the bright spot defects of the red pixels invisible.