JPH06201516A - Generating device of pseudodefect for liquid crystal panel - Google Patents

Abstract

(57) [Summary] [Purpose] To artificially create a stable and highly accurate liquid crystal panel for visual inspection limit samples. [Structure] The pseudo defect generating device 1 is configured to pseudo-create a state equivalent to a display defect of a product liquid crystal panel by an electric signal and exemplarily display this on the sample liquid crystal panel 2. The pseudo defect generating device 1 includes a background signal generating unit 4, a defect signal generating unit 5, a defective address generating unit 6, and a signal switching unit 7.
It consists of and. The background signal generator 4 generates a background signal used for displaying a predetermined background pattern on the sample liquid crystal panel 2. The defect signal generator 5 generates a defect signal used to display a predetermined defect pattern on the sample liquid crystal panel 2. The defect address generator 6 generates defect address data that specifies the defect position of the sample liquid crystal panel 2. The signal switching unit 7 switches the background signal and the defect signal in accordance with the defect address data to create a composite signal, which is input to the sample liquid crystal panel 2 to exemplarily display a desired display defect.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pseudo defect generating device for liquid crystal panels. More specifically, the present invention relates to a pixel defect generating device for artificially creating a limit sample in a visual inspection of an active matrix type liquid crystal panel.

[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 panel will be briefly described with reference to FIG. As shown in the figure, liquid crystal 203 is filled between the drive substrate 201 and the counter substrate 202 that are bonded together with a predetermined gap. Scanning lines 204 and signal lines 205 that are orthogonal to each other are provided on the inner surface of the drive substrate 201. Pixel electrodes 206 at each intersection
And thin film transistors (TFTs) 207 are arranged in a matrix to define individual pixels. On the other hand, the counter electrode 208 and the color filter layer 209 are formed on the inner surface of the counter substrate 202.
Are formed. The color filter layer 209 has segments of three primary colors of red (R), green (G), and blue (B) and is matched with each pixel electrode 206 to form three types of color pixels. Further, the drive substrates 201 adhered to each other
Polarizing plates 210 and 21 are formed on the outer surfaces of the counter substrate 202 and the counter substrate 202, respectively.
1 is attached. TFT 20 via the scanning line 204
7 is selected and an image signal is written in the pixel electrode 206 through the signal line 205. A voltage is generated between the pixel electrode 206 and the counter electrode 208, and the liquid crystal 203 rises. This is taken out as a change in the amount of transmission of white incident light by a pair of polarizing plates 210 and 211 arranged in crossed Nicols, and color display is performed.

[0003]

If there is an electrical failure or malfunction in the TFT that drives each pixel, it will not operate normally and defective pixels will occur. For example, when the liquid crystal panel is driven in the normally white mode, if there is a leak current defect in the TFT, a so-called bright spot defect occurs. Conversely, if the TFT has a short-circuit fault, a dark spot defect occurs. Since such a pixel defect significantly impairs the display quality of the active matrix type liquid crystal panel, the display appearance inspection is usually performed at the shipping stage. By the way, liquid crystal panels are used for TVs, projectors,
The allowable level of display defects including pixel defects differs depending on the purpose of use such as a viewfinder for a video camera. When setting the permissible level, it is general to make an appearance limit sample to align the inspector. However, it is practically impossible to prepare appropriate appearance limit sample samples according to various items such as defect types (bright spot defect, dark spot defect), generation position, hue, and brightness level.
In addition, the display defect of the liquid crystal panel selected as the sample sample is often unstable, and the degree of the defect may change with time. For this reason, there is a problem in that, when it is determined whether or not the actually observed defect is within an allowable level, variations occur and the accuracy of appearance inspection deteriorates.

[0004]

In view of the above-mentioned problems of the conventional technique, the present invention artificially creates a desired display defect,
The purpose is to provide a stable limit sample required for visual inspection. In order to achieve such an object, a device for generating a pseudo defect for a liquid crystal panel was devised. That is, the pseudo defect generating apparatus according to the present invention is a device for pseudo-creating a state equivalent to a display defect of a product liquid crystal panel by an electric signal and displaying this on the sample liquid crystal panel as an example. More specifically, the pseudo defect generating device for a liquid crystal panel includes a background signal generating section, a defect signal generating section, a defective address generating section, and a signal switching section. The background signal generation unit generates a background signal used for displaying a predetermined background pattern on the sample liquid crystal panel.
The defect signal generator also generates a defect signal used for displaying a predetermined defect pattern on the sample liquid crystal panel. The defect address generation unit generates defect address data that specifies a defect position of the sample liquid crystal panel. The signal switching unit switches the background signal and the defect signal according to the defect address data to create a composite signal, which is input to the sample liquid crystal panel to exemplarily display a desired display defect. The background signal generator, the defect signal generator or the defect address generator can freely set the type, position, hue or brightness of the display defect.

[0005]

According to the present invention, the display defect of the active matrix type liquid crystal panel is exemplarily displayed by the synthesized electric signal so that the brightness, position and hue of the display defect can be freely set. As a result, it is possible not only to facilitate the alignment of display defects, to set a permissible level, to determine a standard, and to easily check a standard on a selection line in an appearance inspection process, but also to improve inspection accuracy.

[0006]

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 block diagram showing a basic configuration of a pseudo defect generating device for a liquid crystal panel according to the present invention. As shown in the figure, the pseudo defect generating device 1 is configured to pseudo-create a state equivalent to a display defect of a product liquid crystal panel (not shown) by an electric signal and display this on the sample liquid crystal panel 2 as an example. ing. The sample liquid crystal panel 2 used in this example is an active matrix type color liquid crystal panel having the structure shown in FIG. However, the application range of the present invention is not limited to this, and the present invention can be applied to a simple matrix type liquid crystal panel and the like. The sample liquid crystal panel 2 is a normal product that does not include any defective pixels. Pixel electrodes and switching TFTs arranged in a matrix
In addition to the pixel array consisting of, etc., the peripheral drive parts such as the vertical scanning circuit and the horizontal scanning circuit are also built in on the same substrate, and the pixel array is sequentially driven according to the timing signal input from the outside to obtain a desired image. Display.

The pseudo defect generating device 1 is composed of a timing signal generating section 3, a background signal generating section 4, a defect signal generating section 5, a defective address generating section 6, a signal switching section 7 and the like. The timing signal generator 3 generates a timing signal for driving the sample liquid crystal panel 2. The timing signal includes a start signal and a clock signal supplied to the vertical scanning circuit and the horizontal scanning circuit. The background signal generator 4 generates a background signal used for displaying a predetermined background pattern on the sample liquid crystal panel 2. It is configured so that the brightness and hue of the displayed background can be adjusted. The defect signal generator 5 generates a defect signal used to display a predetermined defect pattern on the sample liquid crystal panel 2. The defect signal generator 5 is configured so that the type of defect pattern, hue, brightness level, etc. can be freely set. The defect address generation unit 6 generates defect address data that specifies a defect position of the sample liquid crystal panel (for example, an XY address of the active matrix pixel array). The signal switching unit 7 switches the background signal and the defect signal according to the defect address data to create a composite signal,
Input to the sample liquid crystal panel 2 to display desired display defects as an example. The defect signal 5 is selected only when the address of the pixel designated by the defect address generator 6 is output on the sample liquid crystal panel 2, and the background signal is selected otherwise. The timing signal generator 3, the background signal generator 4, and the defect signal generator 5 described above are controlled in synchronization with each other, and the background signal and the defect signal are output in serial form and sequentially distributed to individual pixels. ing.

FIG. 2 is a circuit diagram showing a concrete configuration example of the above-mentioned signal switching section 7. The signal switching unit 7 includes a first changeover switch SW1 and a second changeover switch SW2 which are complementary to each other. SW1 is composed of a transmission gate element including a pair of P-channel transistor PCH and N-channel transistor NCH. SW2 is also a pair of P-channel transistors PCH
And a N-channel transistor NCH. A background signal is supplied to the input terminal of SW1, while its output terminal is connected to a sample liquid crystal panel (not shown). SW1 P
Defective address data is supplied to the gate terminal on the channel transistor side, and inverted data thereof is supplied to the gate terminal on the N channel transistor side via the inverter 8. On the other hand, a defect signal is supplied to the input terminal of SW2, and the output terminal is connected to the sample liquid crystal panel. or,
The defective address data inverted through the inverter 9 is applied to the P-channel transistor side gate terminal of SW2, and the address data is directly applied to the N-channel transistor side gate terminal. As a result, SW
A combined signal is generated at the output terminals of 1 and SW2 that are commonly connected. As described above, the supply timing of the defective address data and the transfer timing of the background signal and the defect signal are controlled in synchronization with each other.

The operation of the pseudo defect generating apparatus shown in FIGS. 1 and 2 will be described in detail with reference to the timing chart of FIG. In this example, the sample liquid crystal panel is driven by so-called one field, and the image signal is inverted for each field around a predetermined reference level. First, as shown in (a), defective address data representing the positions of defective pixels are sequentially read from the defective address generator 5 in response to a timing signal. In this example, for simplicity, one defective pixel is designated on the display screen.
The corresponding address data is read for each field.

Next, as shown in (b), a background signal is supplied to the input terminal of the first changeover switch SW1 (see FIG. 2). This background signal is inverted for each field around the reference level, and its amplitude value is set to a predetermined level. The brightness of the displayed background can be set by adjusting the amplitude value. For example, a black background display can be obtained by setting the amplitude level above the threshold voltage of the liquid crystal in the normally white mode. The background signal can be regarded as a waveform in which signal components corresponding to individual pixels are arranged in time series. The shaded signal component corresponds to the above-described defective address data. As described above, the read timing of defective address data and the transfer timing of the shaded signal component are synchronized with each other. As shown in Figure 2,
When the defective address data is input to the gate terminal of the first changeover switch SW1, the transmission gate element is temporarily cut off and the shaded background signal component is separated from the output side. When the defective address data is released, the transmission gate element becomes conductive again and the background signal is directly supplied to the output side.

On the other hand, as shown in (c), a defect signal is supplied to the input terminal of the second changeover switch SW2 (see FIG. 2). This defect signal has a predetermined amplitude level, and its polarity is inverted every field. The amplitude level can be adjusted as appropriate to set the brightness of the defect display.

Finally, as shown in (d), the amplitude voltage level of the defective signal is fitted into the portion of the background signal component cut out to obtain a combined signal. That is, when the defective address data is read, the transmission gate element of the second changeover switch SW2 becomes conductive and a defective signal having a predetermined amplitude level is supplied to the liquid crystal panel side instead of the background signal. The amplitude level or voltage level of this defect signal is set to a value necessary to generate a pseudo pixel defect.

FIG. 4 shows a case where an active matrix type liquid crystal panel is driven in a normally white mode.
6 is a graph showing the relationship between pixel transmittance and applied voltage. In the normally white mode, the pixel transmittance reaches 100% when no voltage is applied, and the transmittance becomes 0% when the applied voltage is increased to, for example, 5V. If the applied voltage is set to an intermediate level, it is possible to obtain a desired gradation display. In the present invention, for example, the voltage level of the background signal is set to 5V and the voltage level of the defect signal is set to 1V. Therefore, it is possible to obtain a liquid crystal panel for a visual inspection sample in which white defects or bright spot defects are scattered in a black background in the normally white mode. By setting the voltage of the defect signal to the intermediate level,
The allowable limit range of bright spot defects can be displayed freely. On the contrary, by setting the voltage level of the background signal to 1 V and the voltage level of the defect signal to 5 V, a sample liquid crystal panel for appearance inspection in which black defects or dark spot defects are scattered in the white background is created. Is also possible.

FIG. 5 is a schematic view showing a display example of the sample liquid crystal panel 100 thus created. In this example, the background portion 116 is set to black on the display screen 115. Bright spot defects 117 are scattered at designated positions on the black background. In this example, the allowable number of green bright spot defects G is 1, the allowable number of red bright spot defects is 2, and the allowable number of blue bright spot defects is 3. Further, the luminance of the permissible limit level is displayed for each color bright spot defect. As described above, according to the present invention, it is possible to freely set the type, position, hue or brightness of the display defect.

Finally, FIG. 6 is a perspective view showing a structural example of a liquid crystal panel visual inspection apparatus to which the pseudo defect generating apparatus according to the present invention is applied. A turntable 102 that is index-driven is mounted on the base 101. A plurality of positioning portions are assigned to the turntable 102, and the inspection liquid crystal panel to be inspected is positioned and mounted. A supply tool 103 is attached, and the inspection liquid crystal panels are sequentially taken out from the tray 104 and supplied to the turntable 102. A video camera 105 is mounted above the turntable 102 and a backlight 106 is stored below the measurement stage. The video camera 105 images the inspection liquid crystal panel 107 transferred by the index drive of the turntable 102. The captured image of the inspection liquid crystal panel 107 is enlarged and displayed on the monitor 109 on the right side. In order to perform a visual inspection during operation, the inspection liquid crystal panel 107 is supplied with a test image signal via the probe 108 to perform a predetermined display operation. The appearance inspection result is input by operating the determination switch 110. An ejection tool 111 is provided on the downstream side of the measurement stage, and the inspected liquid crystal panels are sorted into non-defective products and defective products according to the input determination result and stored in a predetermined tray.

An image of a sample liquid crystal panel produced according to the present invention is enlarged and displayed on the left monitor 112 arranged on the base 101. In this example, an enlarged image obtained by capturing an image of the sample liquid crystal panel with a video camera is stored in a recording medium in advance and set on the monitor 112. Therefore,
The inspector can perform the appearance inspection with extremely high accuracy by comparing the image of the inspection liquid crystal panel enlarged and displayed on the monitor 109 on the right side with the image of the sample liquid crystal panel enlarged and displayed on the monitor 112 on the left side. . Note that the application example of the present invention is not limited to this, and for example, the actual sample liquid crystal panel can also be used to align a plurality of inspectors.

[0017]

As described above, according to the present invention, it is possible to arbitrarily set the type, hue, luminance level, position, etc. of the pixel defect and display it on the sample liquid crystal panel. There is an effect that the alignment work at the time of setting can be easily performed. Further, since it becomes an accurate and stable appearance limit sample, there is an effect that it becomes possible to make a very highly accurate judgment, such as when judging whether or not an actual defect is within an allowable level.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a pseudo defect generating device for a liquid crystal panel according to the present invention.

FIG. 2 is a circuit diagram showing a configuration example of a signal switching unit included in the pseudo defect generating device shown in FIG.

FIG. 3 is a timing chart for explaining the operation of the pseudo defect generating device shown in FIG.

FIG. 4 is a graph showing the relationship between the transmittance and the applied voltage of an active matrix type liquid crystal panel.

FIG. 5 is a schematic view showing a display example of a sample liquid crystal panel created by the pseudo defect generating apparatus according to the present invention.

FIG. 6 is a perspective view showing an example of a liquid crystal panel appearance inspection device to which the pseudo defect generating device for a liquid crystal panel according to the present invention is applied.

FIG. 7 is a perspective view showing a general configuration of an active matrix type color liquid crystal panel.

[Explanation of symbols]

 1 Pseudo-defect generator 2 Sample liquid crystal panel 3 Timing signal generator 4 Background signal generator 5 Defect signal generator 6 Defect address generator 7 Signal switcher

Claims (4)

[Claims] 1. A pseudo defect generation device for a liquid crystal panel, which creates a state equivalent to a display defect of a product liquid crystal panel in a pseudo manner by an electric signal and exemplarily displays this on a sample liquid crystal panel. 2. A background signal generation unit for generating a background signal used for displaying a predetermined background pattern on the sample liquid crystal panel, and a defect signal used for displaying a predetermined defect pattern on the sample liquid crystal panel. A defect signal generating section, a defect address generating section for generating defect address data for designating a defect position of a sample liquid crystal panel, and a sample by creating a composite signal by switching the background signal and the defect signal according to the defect address data. 2. The pseudo defect generating device for a liquid crystal panel according to claim 1, further comprising a signal switching unit which inputs to the liquid crystal panel and exemplarily displays a desired display defect. 3. The pseudo defect generation for a liquid crystal panel according to claim 2, wherein the background signal generation unit, the defect signal generation unit or the defect address generation unit can freely set the type, position, hue or brightness of the display defect. apparatus. 4. A pseudo defect creating method in which a state equivalent to a display defect of a product liquid crystal panel is artificially created by image signal processing and is displayed as an example on a sample liquid crystal panel.