JP4369158B2 - Display panel inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an apparatus for inspecting a display panel such as a liquid crystal display panel, and to a method for inspecting lighting of the display panel.
[0002]
[Prior art]
A display panel such as a liquid crystal display panel is turned on and inspected for quality. Such lighting inspection includes a point defect inspection for inspecting the presence or absence of a luminance defect (that is, a point defect) of each display pixel of the display panel, and an uneven defect inspection for inspecting luminance unevenness in a predetermined area of the display panel. There is.
[0003]
Such lighting inspection includes visual inspection in which the illuminated display panel is visually inspected by an operator, and electrical signals obtained by photographing the illuminated display panel with a sensor such as a line sensor or area sensor. Is carried out by any one of so-called automatic inspections (image processing).
[0004]
In general, an automatic inspection apparatus, like a CCD camera, takes a picture with a sensor in which light receiving elements (sensor elements) are arranged in a line or matrix, and performs image processing on the output signal of the sensor, thereby determining whether the display panel is good or bad. Judgment.
[0005]
As one of this type of automatic lighting inspection apparatus, an area sensor such as a CCD TV camera in which a large number of sensor elements are arranged in a matrix in a plane parallel to a display panel on a stage is used (Patent Document 1). In some cases, a line sensor such as a CCD line sensor in which a large number of sensor elements are arranged in one direction (Y direction) in a plane parallel to the display panel on the stage is used (Patent Document 2).
[0006]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 9-258157
[Patent Document 2]
Japanese Patent Laid-Open No. 11-142288
These inspection devices determine whether the display panel is good or bad by photographing the display panel with a sensor while the display panel is lit, and performing image processing using the obtained electrical signals. Yes.
[0009]
[Problems to be solved]
However, since the resolution of the area sensor is low, the inspection accuracy is low and it is not suitable for point defect inspection that requires high inspection accuracy. On the other hand, the line sensor is suitable for point defect inspection because of its high resolution, but it takes time to perform processing such as sensor output capturing processing and image processing using captured signals.
[0010]
An object of the present invention is to reduce the image processing time without reducing the inspection accuracy.
[0011]
[Solution, action, effect]
An inspection method according to the present invention includes an area sensor in which a plurality of sensor elements are arranged in a matrix in a state where a display panel to be inspected arranged on a stage is lit, and each of the display panels includes a plurality of sensor elements. The display panel is photographed from the same side by a line sensor arranged in at least a first direction parallel to the line sensor, and an uneven defect inspection and a point defect inspection of the display panel are performed using output signals of the area sensor and the line sensor. Including doing. The uneven defect inspection is performed using an output signal of the area sensor, and the point defect inspection is performed in a second direction intersecting the first direction and parallel to the display panel by moving the line sensor. The movement is performed in the second direction using the output signal of the line sensor.
[0012]
The area sensor has difficulty in recognizing bright spot defect addresses and colors, and it is difficult to obtain high resolution, but it can perform image capture and image processing at high speed, and it can perform signal-to-noise ratio (S) by lighting and photographing for a long time. / N) can be increased. For this reason, at the time of uneven defect inspection, the display panel is photographed by the area sensor, and the presence or absence of uneven brightness is determined using the output signal of the area sensor.
[0013]
On the other hand, the line sensor requires time for image capture and image processing, but can obtain high resolution. For this reason, at the point defect inspection, the display panel is photographed by the line sensor, and the presence or absence of the point defect is determined using the output signal of the line sensor.
[0014]
As described above, the display panel can be imaged with an area sensor or line sensor suitable for the type of inspection, and the presence / absence of a defect can be determined. Therefore, the inspection processing accuracy is not lowered, and the image processing time is shortened.
[0016]
The display panel may be photographed by dividing the display panel into a plurality of regions in the first direction by the plurality of line sensors arranged in alignment in the first direction.
[0017]
Prior to photographing of the display panel by the area sensor, the display panel may be moved with respect to a probe unit disposed above the stage by a driving mechanism.
[0018]
The drive mechanism can move the area sensor in the first direction, the second direction, and a third direction that intersects the first and second directions.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
1 to 5, the inspection apparatus 10 uses a liquid crystal display panel having a rectangular shape as a display panel 12 to be inspected, and is used for an automatic lighting inspection of the panel 12. In the illustrated example, the panel 12 has a plurality of electrodes on each of two adjacent sides.
[0020]
In the following description, two orthogonal directions (directions of adjacent edges (rectangular sides) of the rectangular panel 12) in a plane parallel to the display panel 12 disposed at the inspection position of the inspection apparatus 10 are X. A direction perpendicular to the panel 12 is referred to as a Z direction.
[0021]
The inspection apparatus 10 includes a stage 14 disposed on a frame (not shown) so as to be movable in the horizontal direction. The stage 14 is an inspection stage including a chuck top that receives the panel 12 and a backlight unit that illuminates the received panel 12 from behind.
[0022]
For this reason, the stage 14 can move the received panel 12 two-dimensionally in the X and Y directions parallel to the panel 12 and can move the panel 12 in the Z direction perpendicular to the panel 12. 12 can be rotated angularly about a Z axis perpendicular to it.
[0023]
The stage 14 is movable to a delivery position for delivering the panel 12 to a delivery device such as a transfer robot, and an inspection position for performing a lighting inspection of the panel 12.
[0024]
A substrate 16 is horizontally attached to the frame above the stage 14. The board | substrate 16 has the rectangular hole 18 which can see the stage 14 moved to the test | inspection position from upper direction. The hole 18 has a larger planar dimension than the panel 12.
[0025]
On the substrate 16, the probe unit 20 is disposed at a location corresponding to the rectangular hole 18. In the probe unit 20, a plurality of known probe blocks 22 in which a plurality of probes individually pressed against the electrodes of the panel 12 are arranged in a block are attached to a plate-like probe base 24, and the probe base 24 is attached to the lower surface of the substrate 16. It is attached.
[0026]
The probe base 24 has a rectangular hole 25 that is smaller than the hole 18 of the substrate 16 and larger than the panel 12, and is attached to the substrate 16 so that the hole 25 is coaxial with the hole 18.
[0027]
The probe block 22 is divided into two probe block groups that individually correspond to two adjacent sides of the rectangle. The probe blocks 22 of each probe block group are attached to the probe base 24 so that the tips (needle tips) of the probes are aligned.
[0028]
The inspection apparatus 10 also includes a plurality of line sensors 26 arranged on the substrate 16 in a state of being aligned in a line in the Y direction so as to photograph the panel 12 in a line, and the substrate 16 in order to photograph the panel 12 in a planar shape. And an area sensor 28 disposed above.
[0029]
Each line sensor 26 is a known sensor such as a CCD line sensor in which a plurality of sensor elements are arranged in at least three columns adjacent to each other in the X direction and extending in the Y direction. It is moved in three dimensions by 32 and 34.
[0030]
Each of the X moving mechanisms 30 uses a pair of linear guides having a stator 36 having a long stator region and a mover 38 movably assembled to the stator 36. The stator region is attached to the upper surface of the substrate 16 so that the stator region extends in parallel in the X direction with 18 facing each other. The mover 38 is supported by the stator 36 so as to be movable in the X direction.
[0031]
Each of the Z moving mechanisms 34 also uses a pair of linear guides having a stator 40 having a long stator region and a mover 42 movably assembled to the stator 40. The stator 40 is attached to the mover 38 of the X moving mechanism 30 so that the stator region extends in parallel in the Z direction with the 18 facing each other. The mover 42 is supported by the stator 40 so as to be movable in the Z direction.
[0032]
The Y moving mechanism 32 uses a linear guide having a stator 44 having a long stator region and a plurality of movers 46 movably assembled to the stator 44, and the stator 44 extends in the Y direction. As described above, the stator 44 is supported by the movable element 42 of the Z moving mechanism 34. The mover 46 is supported by the stator 44 so as to be individually movable in the Y direction.
[0033]
The area sensor 28 is a known sensor in which a plurality of sensor elements are arranged in a matrix like a CCD TV camera, and is moved in three directions of X, Y, and Z with respect to the stage 14 by the drive mechanism 48.
[0034]
The drive mechanism 48 includes a Z drive mechanism 50 attached to a frame (not shown) so as to move the area sensor 28 in the Z direction, and an X drive mechanism attached to the Z drive mechanism so as to move the area sensor 28 in the X direction. 52 and a Y drive mechanism 54 attached to the X drive mechanism 52 so as to move the area sensor 28 in the Y direction. Such a drive mechanism 48 can also be configured using three or more linear guides.
[0035]
Each line sensor 26 is supported by the movable element 46 of the Y moving mechanism 32 in a state where the light incident side faces the panel 12 on the stage 14. The area sensor 28 is also supported by the Y drive mechanism 54 of the drive mechanism 48 with its light incident side facing the panel 12 on the stage 14.
[0036]
Each of the above-described linear guides is a known drive mechanism that is commercially available under the name of a linear motor table or the like. Such a drive mechanism generally includes a stator having a plurality of coils arranged in one direction, such as a linear motor, and one or more movers assembled to the stator so as to be movable in the one direction. By supplying AC power to the mover, the mover can be moved relative to the stator and can be maintained at a predetermined position. The stator has a guide that regulates the moving direction of the mover.
[0037]
Referring to FIG. 10, the main control processing device 60 controls the driver 62 to move the area sensor 28 in the X, Y, and Z directions with respect to the panel 12 on the stage 14. Thereby, the X, Y and Z drive mechanisms 52, 54 and 50 of the drive mechanism 48 are individually driven by the driver 62.
[0038]
The main control processor 60 also controls the drivers 64, 66 and 68 to move the line sensor 26 in the X, Y and Z directions with respect to the panel 12. Thereby, the X, Y, and Z moving mechanisms 30, 32, and 34 are driven by the drivers 64, 66, and 68, respectively. Although not shown, the driver 66 of the Y moving mechanism 32 is configured to move the movers 46 individually.
[0039]
The main control processor 60 is further provided with a plurality of capturing circuits 70 provided for each line sensor 26 for capturing the output signal of the line sensor 26 and for each line sensor 26 for performing image processing of the captured signal. A plurality of image processing circuits 72 are controlled.
[0040]
As the main control processing device 60, the capturing circuit 70, and the image processing circuit 72, a general computer can be used. In particular, as the main control processing device 60, it is preferable to use an input device such as a keyboard and a mouse or a computer provided with a display device.
[0041]
However, the functions of these processing devices and processing circuits may be assigned to a single computer, or may be controlled by another processing device that cooperates with the main control processing device 60 to control the drive mechanism 48 and the moving mechanisms 30, 32, and 34. It may be done. Furthermore, the stage 14 may be controlled by any of the main control processing device 60, the other processing device, and the processing device dedicated to the stage.
[0042]
The line sensor 26 takes time for image capturing and image processing, but can obtain high resolution. For this reason, at the time of point defect inspection, the panel 12 is photographed by the line sensor 26, and the presence or absence of point defects is determined using the output signal of the line sensor 26.
[0043]
On the other hand, the area sensor 28 has difficulty in recognizing bright spot defect addresses and colors and is difficult to obtain high resolution, but can perform image capture and image processing at high speed, and can be signaled by lighting and photographing for a long time. The noise-to-noise ratio (S / N) can be increased. For this reason, at the time of uneven defect inspection, the panel 12 is photographed by the area sensor 28 and the presence or absence of uneven brightness is determined using the output signal of the area sensor 28.
[0044]
Next, the operation of the inspection apparatus 10 will be described.
[0045]
Prior to the inspection, the panel 12 is positioned with respect to the probe unit 26. This positioning is performed, for example, by photographing a plurality of locations such as alignment marks on the panel 12 while the panel 12 on the stage 14 is separated from the probe block 22 and the line sensor 26 or the area sensor 28 is moved to a predetermined position. Then, the stage 14 is moved in the X and Y directions by the stage 14 so that those positions are in predetermined positions in the photographed image.
[0046]
In the case of the stage 14 having a function of rotating the panel 12 around the Z axis in an angular manner, the panel 12 is arranged so that the arrangement direction of the display pixels coincides with the arrangement direction of the sensor elements of the line sensor 26. Is rotated angularly about the Z axis.
[0047]
Next, the panel 12 is raised by the stage 14, the electrodes of the panel 12 are pressed by the probes of the probe block 22, the panel 12 is energized, and the backlight in the stage 14 is turned on. In this state, uneven defect inspection and point defect inspection are performed.
[0048]
When inspecting the uneven defect, as shown in FIG. 5, the line sensor 26 is retracted to a position that does not hinder the photographing of the panel 12 by the area sensor 28 by the X, Y, and Z moving mechanisms 30, 32, and 34.
[0049]
In the above state, first, the driver 62 is controlled by the main control processing device 60 to drive the drive mechanism 48 so that the panel 12 is at a predetermined position in the imaging region of the area sensor 28.
[0050]
Next, the main control processing device 60 captures the output signal of the area sensor 28, performs image processing based on the captured signal, and determines the presence or absence of uneven brightness.
[0051]
The uneven defect inspection relates to uneven brightness of the entire panel, and can be performed, for example, by determining whether or not the deviation of brightness between predetermined areas in the image exceeds an allowable value. This determination result is stored in a memory attached to the main control processing device 60.
[0052]
When inspecting a point defect, each mover 46 of the Y moving mechanism 32 is moved in the Y direction by the driver 66 so that each line sensor 26 captures a display pixel of a predetermined area in the Y direction of the panel 12 and one display is displayed. The movable element 42 of the Z moving mechanism 34 is moved in the Z direction by the driver 68 so that the pixel is photographed by a plurality of sensor pixels, and the Y moving mechanism 32 and, consequently, the movable element 46 is moved in the Z direction.
[0053]
The number of sensor pixels assigned to one display pixel can be set to three as shown in FIGS. 7, 8, and 9, for example. In the case of color, one display pixel 56 can be a set of R, G, B primary color pixels, that is, a set of primary color pixels necessary to represent one color. However, each primary color pixel may be used as the display pixel 56.
[0054]
7, 8, and 9, three display pixels 56 are illustrated as being photographed by one line sensor 26. However, in actuality, each line sensor 26 has a plurality of n sensor elements arranged in the Y direction, so each line sensor 26 images 3 × n = r display pixels 56.
[0055]
In the above state, the driver 64 is controlled by the main control processing device 60, and the line sensor 26 is moved at least once from one end to the other end in the X direction by the X moving mechanism 30 as shown in FIG. Thereby, the panel 12 is photographed by the line sensor 26.
[0056]
When the line sensor 26 shoots the panel 12, each capture circuit 70 is controlled by the main control processing device 60 to capture the output signal of the corresponding line sensor 26 for each column of sensor elements. The signal captured by each capturing circuit 70 is supplied to the corresponding image processing circuit 72 via the main control processing device 60.
[0057]
Each image processing circuit 72 performs image processing for each display element array based on an input signal for each sensor element array, and determines whether there is a luminance defect in each display element. The luminance defect can be performed, for example, by determining whether the luminance of the display element is within a predetermined allowable value.
[0058]
When the display panel 12 of a different type from the standard display panel 12 is inspected, the panel size (dimension) of the panel 12, the size of the display pixels 56, the arrangement pitch of the display pixels 56, and the display in the Y direction. Depending on the number of pixels, at least one operation selected from the group of increase / decrease of the line sensor 26, adjustment of the position of each line sensor 26 in the Y direction, and adjustment of the position of the line sensor 26 in the Z direction is performed.
[0059]
For example, as shown in FIG. 7A, the standard number of display pixels 56 that can simultaneously photograph one line of display pixels 56 in the Y direction by the standard number of line sensors 26 and that have display pixels 56 of an array pitch. In the case of the display panel 12, the Y moving mechanism 32 is moved up and down by the Z moving mechanism 34, and the line sensor 26 is positioned with respect to the panel 12 so as to photograph one display pixel 56 with a plurality of sensor elements. .
[0060]
However, as shown in FIG. 7B, the number of display pixels is the same as that of the standard panel 12, but when inspecting the display panel 12a having a large arrangement pitch of the display pixels 56, the Y moving mechanism 32 is set to Z. While being raised by the moving mechanism 34, each line sensor 26 is moved in the Y direction by the Y moving mechanism 32, and the line sensor 26 is separated from the panel 12 a so as to photograph one display pixel 56 with a plurality of sensor elements. .
[0061]
Further, as shown in FIGS. 8B and 8C, the display panel 12b having the same panel size but double the number of display pixels as the standard panel 12 shown in FIG. 8A is inspected. When doing so, the inspection apparatus 10 is driven as follows.
[0062]
First, as shown in FIG. 8B, the Y moving mechanism 32 is lowered by the Z moving mechanism 34 to divide the display pixels 56 into two groups of r, and each display pixel 56 of one group is divided into two groups. The line sensor 26 is brought close to the panel 12a so as to photograph with a plurality of sensor elements. In this state, the line sensor 26 is moved once in the X direction together with the Y moving mechanism 32 by the X moving mechanism 30 to photograph the panel 12b.
[0063]
Next, as shown in FIG. 8C, the line sensor 26 captures the next group of display pixels 56 with a plurality of sensor elements, so that the line sensor 26 uses the Y moving mechanism 32 by the size of the pixel r. Moved in the Y direction. In this state, the line sensor 26 is moved once in the X direction together with the Y moving mechanism 32 by the X moving mechanism 30 to photograph the panel 12b.
[0064]
Further, as shown in FIG. 9B, the display pixel arrangement pitch is the same as that of the standard panel 12 shown in FIG. 9A, but the panel size is increased and the number of display pixels is large. When inspecting the panel 12c, the inspection apparatus 10 is driven as follows.
[0065]
First, as shown in FIG. 9B, one or more line sensors 26a are added according to the panel size and the number of display pixels, and the line sensor 26 so that each display pixel 56 is photographed by a plurality of sensor elements. Is moved in the Y and Z directions relative to the panel 12a by the Y and Z moving mechanisms 32 and 34. In this state, the line sensor 26 is moved once in the X direction together with the Y moving mechanism 32 by the X moving mechanism 30 to photograph the panel 12b.
[0066]
As described above, the positions of the plurality of line sensors 26 in the Y direction can be individually changed, and the positions of the line sensors 26 in the Z direction can be changed. As a result, even if the number of sensor elements to be assigned to one display element 56 is the same or different, different types of display panels can be inspected.
[0067]
When the line sensor 26 and the area sensor 28 are provided as described above, the panel 12 can be photographed by the line sensor 26 or the area sensor 28 according to the type of inspection, and the presence or absence of defects can be determined. The image processing time is shortened without lowering.
[0068]
In addition, the line sensor 26 includes a capturing circuit 70 and an image processing circuit 72, and a main control processing device that captures an output signal of the area sensor 28 and performs image processing, and controls the capturing circuit and the image processing circuit. As a result, the image capture time and the image processing time are further shortened.
[0069]
Further, if the capturing circuit 70 and the image processing circuit 72 are provided for each line sensor 26, the image capturing time and the image processing time are further shortened.
[0070]
The present invention can be applied not only to inspection of a liquid crystal display panel but also to inspection of other display panels such as a display panel using a light emitting diode, an organic EL, and the like.
[0071]
The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the present invention.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of an inspection apparatus used in an inspection method according to the present invention, with a part thereof broken away.
FIG. 2 is a perspective view of the inspection apparatus shown in FIG.
FIG. 3 is a plan view of the inspection apparatus shown in FIG.
4 is a cross-sectional view taken along line 4-4 in FIG.
FIG. 5 is a cross-sectional view taken along line 5-5 in FIG.
6 is a diagram showing a state in which the line sensor in the apparatus shown in FIG. 1 is moved in the X direction. FIG.
7 is a diagram showing the relationship between a line sensor and display pixels in order to explain the operation of the apparatus shown in FIG. 1. FIG.
FIG. 8 is a diagram showing a relationship between a line sensor and display pixels in order to explain another operation of the apparatus shown in FIG.
9 is a diagram showing a relationship between a line sensor and a display pixel in order to explain still another operation of the apparatus shown in FIG. 1. FIG.
10 is a block diagram showing an embodiment of an electric circuit in the apparatus shown in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Inspection apparatus 12,12a, 12b, 12c Display panel 14 Stage 16 Board | substrate 18,25 Hole 20 Probe unit 22 Probe block 24 Probe base 26 Line sensor 26a Additional line sensor 28 Area sensor 30, 32, 34 Line sensor X, Y, Z moving mechanism 36, 40, 44 Moving mechanism stator 38, 42, 46 Moving mechanism mover 48 Area sensor driving mechanism 50, 52, 54 Area sensor Z, X, Y drive mechanism 56 Display pixel

Claims (4)

An area sensor in which a plurality of sensor elements are arranged in a matrix in a state where a display panel to be inspected arranged on a stage is lit, and at least a first direction in which each of the plurality of sensor elements is parallel to the display panel Photographing the display panel with the line sensor arranged on the same side, and using the output signals of the area sensor and the line sensor to inspect the display panel for uneven defect inspection and point defect inspection,
The uneven defect inspection is performed using an output signal of the area sensor, and the point defect inspection is performed in a second direction intersecting the first direction and parallel to the display panel by moving the line sensor. A method for inspecting a display panel, which is performed using an output signal of the line sensor by moving in a second direction.   The inspection method according to claim 1, wherein the display panel is photographed by dividing the display panel into a plurality of regions in the first direction by the plurality of line sensors arranged in alignment in the first direction.   3. The inspection method according to claim 1, wherein the display panel is moved with respect to a probe unit disposed above the stage by a driving mechanism prior to imaging of the display panel by the area sensor. .   4. The drive mechanism according to claim 3, wherein the drive mechanism moves the area sensor in the first direction, the second direction, and a third direction intersecting the first and second directions. Inspection method.

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