JP3186360B2 - Inspection method and inspection device for active matrix liquid crystal panel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for testing an active matrix liquid crystal panel. More specifically, the present invention relates to a technique for taking an image of a display screen of an active matrix liquid crystal panel, analyzing recorded image data, and performing an automatic inspection.

[0002]

2. Description of the Related Art In order to clarify the background of the present invention, a general structure of an active matrix liquid crystal panel will first be briefly described with reference to FIG. The active matrix liquid crystal panel 100 has a flat structure in which a liquid crystal layer 103 is sandwiched between a pair of substrates 101 and 102 disposed facing each other with a predetermined gap. Pixel electrodes 104 are arranged in a matrix on the lower substrate 101. Thin film transistors 105 are formed corresponding to the individual pixel electrodes 104. The drain electrode of the thin film transistor 105 is connected to the corresponding pixel electrode 104, the gate electrode is connected to the gate line 106, and the source electrode is connected to the data line 107. On the other hand, a color filter 108 is formed on the inner surface of the upper substrate 102. The color filter 108 has segments divided into RGB ternary colors, and corresponds to each pixel electrode 104. The counter electrode 10 is provided on the surface of the color filter 108.
9 are formed. A pixel is defined by the liquid crystal layer 103 sandwiched between the counter electrode 109 and each pixel electrode 104. Polarizing plates 110 and 111 are attached to the outer surfaces of the pair of substrates 101 and 102, respectively. In such a configuration, the gate lines 106 are sequentially scanned to make the thin film transistors 105 conductive for each row, and an image signal is supplied from each data line 107 and written to the pixel electrode 104 via the conductive thin film transistors 105.
A predetermined voltage is applied between each pixel electrode 104 and the counter electrode 109 according to the written image signal, and the molecular arrangement of the liquid crystal layer 103 changes. This change is converted into a change in transmittance by the pair of polarizing plates 110 and 111. Therefore, when the liquid crystal panel 100 is illuminated with a backlight, a full-color image display can be obtained according to the transmittance of each pixel.

An active matrix liquid crystal panel having such a structure can achieve high definition and miniaturization, and hundreds of thousands of pixels are formed in an integrated manner. Defective pixels are generated due to various factors such as defective characteristics of thin film transistors and short / open failures of wiring patterns such as gate lines and data lines. Since the presence of defective pixels significantly impairs the display quality, it is essential to carry out inspections at the stage of product shipment to eliminate defective products.

Conventionally, an inspection of an active matrix liquid crystal panel has been performed visually. However, inspection items are diversified and individual pixels are miniaturized. Therefore, since a large amount of time is required for visual inspection and it is difficult to make a quantitative and objective judgment on quality, an automatic inspection device has recently been introduced. For example,
An automatic inspection apparatus combining a video camera and an image processing unit is disclosed in JP-A-63-136086 and JP-A-1-189696. As shown in FIG. 5, the conventional automatic inspection apparatus includes a stage 201, on which an active matrix liquid crystal panel 202 to be inspected is mounted. The liquid crystal panel 202 is driven by the drive unit 203 and displays a desired test pattern. A backlight 204 for illumination is arranged below the stage 201. The stage 201 and the backlight 204 are mounted on a rotary table 205. The supply and discharge of the liquid crystal panel 202 to and from the stage 201 are automatically performed by the robot arm 206. A video camera 207 is set above the stage 201, and captures and records a display screen of the liquid crystal panel 202. The video camera 207 is attached to the carriage 208,
Positioning is possible in the X and Y directions.

[0005]

The display screen of a liquid crystal panel to be inspected is captured by a video camera having a built-in image sensor such as a CCD and converted into image data. This image data is recorded in the frame memory. An image processing unit including a computer sequentially reads out image data from a frame memory, performs pixel analysis, and performs an automatic inspection. That is, scanning is performed for all pixels,
The luminance is measured for each pixel, and the presence or absence of a defect is determined by comparing the measured luminance with a predetermined reference level. The quality of the liquid crystal panel is determined based on the result of analyzing all the pixels. Inspection items are extremely diversified, and a large amount of time is required until the completion of the inspection because all the pixels are sequentially analyzed, which is an obstacle in streamlining the manufacturing process.

[0006]

SUMMARY OF THE INVENTION In view of the above-mentioned problems in the prior art, an object of the present invention is to provide a quick and simple method and apparatus for inspecting an active matrix liquid crystal panel. The following measures were taken to achieve this purpose. That is, the present invention provides an inspection method and an inspection apparatus for an active matrix liquid crystal panel including a pixel group arranged in a matrix, a gate line group connected to each row of the pixel group, and a data line group connected to each column of the pixel group. Is provided. The inspection method according to the present invention sequentially scans the gate line group to select each row of the pixel group, and supplies a predetermined drive signal from the input end side of each data line to display the matrix of the pixel group in full lighting. The procedure, the procedure of imaging the pixel group that is all lit and displayed and recording it in the frame memory, and the lighting state of the recorded pixel group from the row located on the open end side of the data line group to the input end side Sequentially performing pixel analysis toward the row.

Further, the inspection apparatus according to the present invention includes a stage, a drive unit, a camera unit, a memory unit, and an image processing unit. The stage mounts an active matrix liquid crystal panel to be inspected. The drive unit sequentially scans the gate line group of the active matrix liquid crystal panel and applies a predetermined drive signal through the input end side of each data line to display the matrix of the pixel group in full lighting. The camera unit picks up an image of the pixel group that is all lit and displayed. The memory unit records the lighting state of the imaged pixel group. The image processing unit accesses the memory unit and analyzes the lighting state of the sequentially recorded pixel group from the row located on the open end side of the data line group to the row located on the input end side.

[0008]

The inspection method and inspection apparatus according to the present invention can quickly detect a pixel defect (line defect) continuously occurring along a data line. This type of line defect is caused by a disconnection failure of the data line. If there is a disconnection failure on the way from the signal input end to the open end of the data line, all pixel columns along the open end from the disconnection point become dark spot defects. That is, since no image signal is supplied to the pixels after the disconnection point, when the active matrix liquid crystal panel is fully lit, the pixels appear as a column of dark pixels and display quality is significantly impaired. In view of this point, in the present invention, the sequential pixel analysis is performed from the row located on the open end side of the data line group to the row located on the input end side. When there is a disconnection failure of the data line, a dark spot defect is necessarily included in the pixel row located at the open end. If the next row also includes a dark spot defect in the same column, a disconnection failure of the data line can be immediately detected. Therefore, without performing pixel analysis on the entire display screen, it is possible to immediately determine a defect and stop the subsequent inspection, thereby shortening the working time.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing a basic configuration of an active matrix liquid crystal panel inspection apparatus according to the present invention. This inspection apparatus is divided into an imaging unit 1 and a determination unit 2. Both are connected to each other by a cable via an RS232C interface or the like. The imaging unit 1 has basically the same structure as that shown in FIG. That is, a stage 3 is provided, on which an active matrix liquid crystal panel 4 to be inspected is placed. Note that a light source unit 5 for illumination is incorporated in a lower portion of the stage 3. The active matrix liquid crystal panel 4 basically has a flat structure shown in FIG. 4, and is connected to a pixel group arranged in a matrix, a gate line group connected to each row of the pixel group, and each column of the pixel group. And a data line group. A drive unit 6 is connected to the liquid crystal panel 4 via a probe (not shown) or the like. The drive unit 6 sequentially scans the gate line group of the liquid crystal panel 4 and applies a predetermined drive signal through the input end of each data line to display the matrix of the pixel group in full lighting. A camera unit 7 is set above the stage 3, and captures an image of a pixel group of the liquid crystal panel 4 that is lit and displayed. The camera unit 7 includes, for example, a lens system 8 and a CC.
D9 and a high-resolution video camera or the like. The lens system 8 can be moved and adjusted in the X and Y directions, and accurately matches the imaging position of the liquid crystal panel 4. Further, the camera unit 7 is adjustable in rotation with respect to the optical axis, and captures an image at an angle of view that matches the display screen of the liquid crystal panel 4. If a rotation error is included in the screen of the liquid crystal panel 4 and the angle of view, an inconvenience will occur in the subsequent image processing.

On the other hand, the determination unit 2 includes a CPU 10 and controls the entire system. The CPU 10 is connected to the control unit 23 and the light source unit 5 on the imaging unit 1 side via a cable. The control unit 23 is a CPU 10
To control the operation of the camera unit 7. At the same time, the image data output from the CCD 9 is transferred to the CPU 10. The CPU 10 also issues commands for adjusting the position of the lens system 8, adjusting the light amount of the light source unit 5, and the like. The determination unit 2 includes a memory unit 11 that receives image data sent from the CCD 9 via the CPU 10 and records the lighting state of the captured pixel group. As schematically shown, the imaged pixel group is recorded on the frame memory 12, and the pixel group included in the liquid crystal panel 4 and the pixel group recorded in the memory unit 11 are one.
There is a one-to-one correspondence. Therefore, the following description will be made without distinguishing between actual pixels and recorded pixels unless otherwise required. Since the liquid crystal panel 4 is imaged in a fully lit display,
If there is no defect, only the bright spot pixels are recorded on the frame memory. However, since some defects are usually included, dark pixels are included as shown in the figure. If a plurality of dark spot pixels continue on the same column, a line defect occurs. An image processing unit 13 is connected to the memory unit 11, and the memory unit 11 is accessed to sequentially record data from a row located on the open end side of the data line group to a row located on the input end side. The blinking state of the pixel group is analyzed. In the illustrated example, on the frame memory 12, the open end side of the data line group is the bottom row, and the input end side is the top row. Therefore, in this example, the memory units 11 are sequentially accessed from the bottom row to the top row as indicated by arrows.

Next, a method for testing an active matrix liquid crystal panel according to the present invention will be described in detail with reference to FIG. As described above, the active matrix liquid crystal panel 4
Has a group of pixels 14 arranged in a matrix, a gate line 15 connected to each row of the pixels 14, and a data line 16 connected to each column of the pixels 14. When testing the active matrix liquid crystal panel 4 having such a configuration, first, the gate lines 15 are sequentially scanned to select each row of the pixels 14, and a predetermined drive signal is input from the input terminal 17 side of each data line 16. Then, the entire matrix of the pixels 14 is supplied and displayed. In the illustrated example, the input end 17 of the data line 16 is located at the upper end of the screen, and the open end 18 is located at the lower end of the screen. Next, a procedure of taking an image of the pixel 14 which is displayed in all the lighting and recording it in the frame memory is performed. Subsequently, the recorded pixel 14
Is sequentially performed from the bottom row 19 located on the open end 18 side of the data line 16 to the top row 20 located on the input end 17 side of the data line 16.

In the illustrated example, the screen of the liquid crystal panel 4 includes two line defects, which are included in columns 21 and 22. In the case of a line defect, a dark spot pixel always appears on the bottom row 19. Also, a dark pixel appears in the upper row. As described above, when two or more dark spot defective pixels are consecutive on the same column, there is a high possibility that the pixel is a line defect. However, in some cases, there is a probability that two independent dark spot defects exist accidentally along the column direction. Therefore, the pixel analysis of the third row from the lower end is continued, and if a dark pixel defect is found on the same column, a line defect can be detected almost certainly. As described above, pixel analysis is performed for a predetermined number of rows from the bottom row,
When a plurality of dark spot defective pixels are detected on the same row, the pixel analysis is stopped at that point, and the liquid crystal panel 4 is excluded as a defective product. Since the following pixel analysis can be omitted, the detection time can be significantly reduced. In the illustrated example, for example, a disconnection failure has occurred in the data line corresponding to the column 21 at the position of the second row from the top. Therefore, all the pixels in the third row and below in the column 21 are defective pixels. Similarly, for column 22, a disconnection fault has occurred at the position of the corresponding data line in the sixth row from the top. Therefore, all the subsequent pixels become dark spot defects.

Finally, the mode of line defect generation will be briefly described for reference with reference to FIG. FIG. 3 is an equivalent circuit diagram of the active matrix liquid crystal panel. As shown, a gate line 51 extends in the row direction. The data line 52 extends along the column direction. A thin film transistor 53 is formed at the intersection of each gate line 51 and data line 52. A liquid crystal pixel 54 is connected to a drain electrode of the thin film transistor 53. The other end of the liquid crystal pixel 54 is connected to a counter electrode 55. Also, the liquid crystal pixel 54
And a storage capacitor 56 is connected in parallel. The gate electrode of the thin film transistor 53 is connected to the corresponding gate line 51. The source electrode is connected to the corresponding data line 52.

Each gate line 51 is connected to a vertical scanning circuit 57. On the other hand, the input end of each data line 52 is connected to a common signal line 59 via a switching element 58. Each switching element 58 is sequentially controlled to open and close by a horizontal scanning circuit 60.

In such a configuration, when each gate line 51 is line-sequentially scanned by the vertical scanning circuit 57, the thin film transistors 53 in each row are turned on. In synchronization with this, when each switching element 58 is sequentially switched to the conductive state by the horizontal scanning circuit 60, the drive signal is sampled from the common signal line 59 to each data line 52, and the corresponding drive signal is supplied via the conductive thin film transistor 53. The data is written in the liquid crystal pixel 54 and the storage capacitor 56 to perform a desired image display. However, if an interruption occurs in the data line 52, an image signal cannot be supplied to the thin film transistor connected from the disconnection portion toward the open end.
Therefore, when a disconnection failure occurs, a line defect occurs as described above. As can be seen from this defect mode,
In the case of a line defect, a dark spot defect always appears on the pixel electrode of the row located on the open end side. The present invention is characterized by shortening the inspection time by utilizing this fact. In general, the gate line 51 is formed of the same material as the gate electrode of the thin film transistor, so that a disconnection failure hardly occurs. On the other hand, the data line 52 is provided above the gate line 51, and is formed by patterning metal aluminum or the like in a stripe shape. The probability of occurrence of a disconnection failure is high due to the influence of the unevenness of the base. Therefore, by first analyzing the line defects in the column direction with a high probability of occurrence,
Inspection time can be reduced.

[0016]

As described above, according to the present invention, in the pixel analysis of the active matrix liquid crystal panel, by sequentially performing the analysis from the last row located on the open end side, the line defect can be easily and in the shortest time. Can be detected, and defective liquid crystal panels can be eliminated. According to the present invention,
Since there is no need to employ a complicated pixel analysis program,
The inspection device can be simplified and the inspection time can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic block diagram showing an inspection device for an active matrix liquid crystal panel according to the present invention.

FIG. 2 is an explanatory diagram showing a method for inspecting an active matrix liquid crystal panel according to the present invention.

FIG. 3 is an equivalent circuit diagram of an active matrix liquid crystal panel tested according to the present invention.

FIG. 4 is a perspective view showing a general configuration of an active matrix liquid crystal panel.

FIG. 5 is a perspective view showing a general configuration of a conventional active matrix liquid crystal panel inspection apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Imaging part 2 Judgment part 3 Stage 4 Liquid crystal panel 5 Light source unit 6 Drive unit 7 Camera unit 8 Lens system 9 CCD 10 CPU 11 Memory unit 12 Frame memory 13 Image processing unit 14 Pixel 15 Gate line 16 Data line 17 Input end 18 Open End 23 control unit

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-209422 (JP, A) JP-A-4-133088 (JP, A) JP-A-63-136086 (JP, A) JP-A-1- 189696 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) G02F 1/1368 G02F 1/13 101

Claims (3)

(57) [Claims] 1. An active matrix liquid crystal panel inspection method comprising: a pixel group arranged in a matrix; a gate line group connected to each row of the pixel group; and a data line group connected to each column of the pixel group. A procedure of sequentially scanning the gate line group to select each row of the pixel group and supplying a predetermined drive signal from the input end side of each data line to display the matrix of the pixel group in a fully lit state; A procedure for imaging the group and recording it in the frame memory; and a procedure for sequentially analyzing the recorded lighting state of the pixel group from the row located on the open end side of the data line group to the row located on the input end side. An inspection method for an active matrix liquid crystal panel having: 2. An active matrix liquid crystal panel inspection apparatus comprising: a pixel group arranged in a matrix; a gate line group connected to each row of the pixel group; and a data line group connected to each column of the pixel group. A stage on which an active matrix liquid crystal panel to be inspected is placed; and a gate line group of the active matrix liquid crystal panel is sequentially scanned, and a predetermined drive signal is applied through an input end of each data line to form a complete matrix of pixel groups. A drive unit for lighting and displaying, a camera unit for capturing an image of a pixel group that is fully lit and displayed, a memory unit for recording a lighting state of the captured pixel group, and an open end of the data line group for accessing the memory unit From the line located on the input end side to the line located on the input end side,
An inspection apparatus for an active matrix liquid crystal panel, comprising: an image processing unit that analyzes a lighting state of a sequentially recorded pixel group. 3. A pixel group arranged in a matrix and each row of the pixel group
Connected gate line group and data connected to each column of pixel group
Manufacture of active matrix liquid crystal panels that form lines
In the fabrication method, it is assumed that the gate line group is sequentially scanned to select each row of the pixel group.
A predetermined drive signal is supplied from the input end of each data line.
To display the matrix of the pixel group with full lighting, and capture the image of the pixel group with all lighting displayed and record it in the frame memory
And the lighting state of the recorded pixel group is changed to the open end side of the data line group.
From the line located at the input end to the line located at the input end side.
And a next pixel analysis step.
A method for manufacturing a submatrix liquid crystal panel.