JP3932873B2 - Inspection apparatus and inspection method for liquid crystal panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inspection apparatus and an inspection method for a liquid crystal panel that enable inspection of light leak pixel unevenness.
[0002]
[Prior art]
A liquid crystal device such as a liquid crystal light valve is configured by sealing liquid crystal between two substrates such as a glass substrate and a quartz substrate. In a liquid crystal light valve, active elements such as thin film transistors (hereinafter referred to as TFTs) are arranged in a matrix on one substrate, a counter electrode is arranged on the other substrate, and sealed between both substrates. By changing the optical characteristics of the stopped liquid crystal layer according to the image signal, it is possible to display an image.
[0003]
A liquid crystal panel used for a projector uses a TN (twisted nematic) liquid crystal having a high transmittance and a relatively high contrast ratio. As a drive device, a high-temperature polysilicon TFT that has a relatively high light leakage resistance and enables high-definition display is mainly used.
[0004]
The optical characteristics of the liquid crystal layer are controlled by changing the alignment of the liquid crystal molecules by applying a voltage based on the video signal to the liquid crystal layer. In order to define the alignment of liquid crystal molecules when no voltage is applied, an alignment film is formed on the surface of one substrate (active matrix substrate) and the other substrate (counter substrate) in contact with the liquid crystal layer, and the alignment film is rubbed Apply.
[0005]
By the way, the TFT element has a characteristic that its characteristics are changed by the influence of light. Therefore, a light-shielding film that shields light is formed on at least a portion facing the TFT element portion on the element substrate or the counter substrate so that light is not irradiated to the channel region or the channel adjacent region of the TFT element portion.
[0006]
In recent years, liquid crystal projectors have adopted high-power lamps and improved light utilization efficiency for the purpose of increasing the brightness of projected images. In addition, the liquid crystal device employed in the projector is also designed to improve the projection light transmittance by increasing the aperture ratio of the pixels in order to cope with higher brightness.
[0007]
[Problems to be solved by the invention]
However, although the light shielding property with respect to the TFT element is enhanced, light incident from an oblique direction causes multiple reflection within the laminated structure, and is irradiated to the channel region and the channel adjacent region of the TFT element. Then, a light leak current is generated in the TFT element, the characteristics of the TFT element are changed, and the image quality is deteriorated.
[0008]
Such pixel unevenness due to light leakage (hereinafter referred to as light leakage pixel unevenness) has not been manifested until high-intensity light is transmitted through the liquid crystal panel. For this reason, at present, the inspection system for such light leak pixel unevenness is not prepared, and it is not included in various inspection processes for the liquid crystal panel.
[0009]
That is, conventionally, it was possible to detect light leak pixel unevenness for the first time when a finished liquid crystal panel was mounted on a liquid crystal device such as a projector and actually used.
[0010]
Note that pixel unevenness may be inspected by an image that is transmitted through the liquid crystal panel and projected onto the screen. However, the light leak pixel unevenness is greatly influenced by the light incident distribution from the light source, and the inspection device having a different light incident distribution from the liquid crystal device to which the liquid crystal panel is actually applied is accurate only for the light leak pixel unevenness. There was a problem that quantitative determination was impossible.
[0011]
An object of the present invention is to provide an inspection apparatus and an inspection method for a liquid crystal panel capable of accurately and reliably inspecting light leak pixel unevenness for each light incident condition.
[0012]
[Means for Solving the Problems]
According to an aspect of the present invention, an inspection apparatus for a liquid crystal panel includes a plurality of TFTs, and makes light incident on an incident surface of the liquid crystal panel to which signals are given to the plurality of TFTs so as to project a predetermined image. A light source device, and an optical axis of the light source device that is rotatable within a predetermined plane perpendicular to the incident surface of the liquid crystal panel to change a light incident angle of the light from the light source device to the incident surface of the liquid crystal panel An incident angle control unit that controls the image, an image acquisition unit that acquires an image of the light emitted from the liquid crystal panel, and the light incident of the light that is incident on the incident surface of the liquid crystal panel using the acquired image Determination means for determining light leak pixel unevenness for each angle. The image acquisition unit acquires the first image when the light incident angle is 0 degrees, and acquires the second image when the light incident angle is other than 0 degrees. Further, the determination unit determines the light leak pixel unevenness with respect to the light incident angle when the second image is acquired by using the first image as a reference for the second image.
[0013]
According to such a configuration, the influence of pixel unevenness due to causes other than light leakage to the TFT can be reduced, and light leak pixel unevenness can be determined for each light incident angle.
[0014]
The light source device includes a two-lamp type light emitting unit and a condensing optical system that condenses light from the light emitting unit.
[0015]
According to such a configuration, by using a two-lamp type light emitting unit, light with sufficient intensity can be incident on the incident surface of the liquid crystal panel, and light leak pixel unevenness can be forcibly generated. . Further, since light close to parallel light can be made incident on the incident surface of the liquid crystal panel by the condensing optical system, light leak pixel unevenness is more likely to occur. In addition, the change of the image due to the projection light can be made steep so that the characteristics can be easily determined.
[0016]
The liquid crystal panel further includes a rotation mechanism for rotating the liquid crystal panel in a plane perpendicular to the optical axis of the light source device.
[0017]
According to such a configuration, it is possible to inspect not only the horizontal direction of the incident surface of the liquid crystal panel but also the characteristics in the vertical direction.
[0018]
The incident angle control means may rotate the optical axis of the light source device in two planes perpendicular to each other in two predetermined planes perpendicular to the plane of incidence of the liquid crystal panel.
[0019]
According to such a configuration, it is possible to inspect not only the horizontal direction but also the vertical characteristic of the incident surface of the liquid crystal panel without rotating the liquid crystal panel.
[0020]
Further, the light source device makes parallel light incident on an incident surface of the liquid crystal panel.
[0021]
According to such a configuration, light leak pixel unevenness is likely to occur, and the change of the liquid crystal panel image due to the projection light can be made steep to facilitate the determination of the characteristics.
[0022]
The incident angle control means can change the light incident angle on the incident surface of the liquid crystal panel by a predetermined angle unit.
[0023]
According to such a configuration, the characteristics of the liquid crystal panel according to the incident angle of light can be finely inspected in arbitrary angle units.
[0024]
Further, the incident angle control means changes the light incident angle on the incident surface of the liquid crystal panel within a range of 0 degrees to ± 20 degrees.
[0025]
According to such a configuration, it is possible to inspect the characteristics at all incident angles until the light leak pixel unevenness characteristic of the liquid crystal panel is saturated.
[0026]
The image acquisition unit may include a screen on which projection light from the liquid crystal panel is projected, and an imaging unit that captures an image on the screen.
[0027]
According to such a configuration, the projection light from the liquid crystal panel is projected on the screen, and the image on the screen is captured by the imaging unit. Thereby, the image obtained by the liquid crystal panel is accurately detected.
[0028]
The determination unit may detect the light leak pixel unevenness when the second image is acquired by pattern recognition with respect to a difference between the first image and the second image.
[0029]
According to such a configuration, pattern recognition is performed on the first image and the second image. This cancels pixel unevenness due to causes other than light leakage to the TFT. As a result, the influence of pixel unevenness due to causes other than light leakage to the TFT can be reduced, and light leak pixel unevenness can be detected for each light incident angle.
[0030]
According to an aspect of the present invention, a liquid crystal panel inspection method includes a plurality of TFTs, and allows light to be incident on an incident surface of the liquid crystal panel in which signals are given to the plurality of TFTs so as to project a predetermined image. A procedure, a procedure for changing a light incident angle of the light on the incident surface of the liquid crystal panel within a predetermined plane perpendicular to the incident surface of the liquid crystal panel, and an image obtained by the light emitted from the liquid crystal panel. An image acquisition procedure and a determination procedure for determining light leak pixel unevenness for each light incident angle of the light incident on the incident surface of the liquid crystal panel using the acquired image. The image acquisition procedure includes a procedure for acquiring the first image when the light incident angle is 0 degrees, and a procedure for acquiring the second image when the light incident angle is other than 0 degrees. , Including. Further, the determination unit determines the light leak pixel unevenness with respect to the light incident angle when the second image is acquired by using the first image as a reference for the second image.
[0031]
According to such a configuration, the influence of pixel unevenness due to causes other than light leakage to the TFT can be reduced, and light leak pixel unevenness can be determined for each light incident angle.
[0032]
The determination procedure may include a procedure of detecting the light leak pixel unevenness when the second image is acquired by pattern recognition with respect to a difference between the first image and the second image.
[0033]
According to such a configuration, pattern recognition is performed on the first image and the second image. This cancels pixel unevenness due to causes other than light leakage to the TFT. As a result, the influence of pixel unevenness due to causes other than light leakage to the TFT can be reduced, and light leak pixel unevenness can be detected for each light incident angle.
[0036]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an explanatory view showing an inspection apparatus for a liquid crystal panel according to the first embodiment of the present invention. FIG. 2 is an equivalent circuit diagram of various elements and wirings in a plurality of pixels constituting the pixel region of the liquid crystal device. FIG. 3 is a plan view of an element substrate such as a TFT substrate as viewed from the counter substrate side together with each component formed thereon, and FIG. 4 is an assembly process in which the element substrate and the counter substrate are bonded together to enclose liquid crystal. It is sectional drawing which cut | disconnects and shows the liquid crystal device after completion | finish at the position of the HH 'line | wire of FIG. FIG. 5 is a cross-sectional view showing the liquid crystal device in detail.
[0037]
In this embodiment, by making it possible to appropriately set the incident distribution of light to the liquid crystal panel, the incident light distribution causing the light leak pixel unevenness is determined for each liquid crystal panel, and the light leak pixel unevenness characteristic of the liquid crystal is determined. This makes it possible to determine accurately and reliably.
[0038]
First, the structure of a liquid crystal panel to be inspected will be described with reference to FIGS.
[0039]
As shown in FIGS. 3 and 4, the liquid crystal panel is configured by sealing a liquid crystal 50 between an element substrate 10 such as a TFT substrate and a counter substrate 20. On the element substrate 10, pixel electrodes and the like constituting pixels are arranged in a matrix. FIG. 2 shows an equivalent circuit of elements on the element substrate 10 constituting the pixel.
[0040]
As shown in FIG. 2, in the pixel region, a plurality of scanning lines 3a and a plurality of data lines 6a are wired so as to cross each other, and a pixel electrode is formed in a region partitioned by the scanning lines 3a and the data lines 6a. 9a are arranged in a matrix. A TFT 30 is provided corresponding to each intersection of the scanning line 3 a and the data line 6 a, and the pixel electrode 9 a is connected to the TFT 30.
[0041]
The TFT 30 is turned on by the ON signal of the scanning line 3a, whereby the image signal supplied to the data line 6a is supplied to the pixel electrode 9a. A voltage between the pixel electrode 9 a and the counter electrode 21 provided on the counter substrate 20 is applied to the liquid crystal 50. In addition, a storage capacitor 70 is provided in parallel with the pixel electrode 9a, and the storage capacitor 70 makes it possible to hold the voltage of the pixel electrode 9a for a time that is, for example, three orders of magnitude longer than the time when the source voltage is applied. The storage capacitor 70 improves the voltage holding characteristic and enables image display with a high contrast ratio.
[0042]
FIG. 5 is a schematic cross-sectional view of a liquid crystal panel focusing on one pixel.
[0043]
A groove 11 is formed in the element substrate 10 such as glass or quartz in order to adjust the step shape when the element substrate is completed. A TFT 30 having an LDD structure is formed on the groove 11 with a light shielding film 12 and a first interlayer insulating film 13 interposed therebetween. The groove 11 flattens the boundary surface between the TFT substrate and the liquid crystal 50.
[0044]
The TFT 30 includes a scanning line 3a that forms a gate electrode through an insulating film 2 on a semiconductor layer in which a channel region 1a, a source region 1d, and a drain region 1e are formed. The light shielding film 12 is formed in a region corresponding to the formation region of the TFT 30, a formation region such as a data line 6a and a scanning line 3a described later, that is, a region corresponding to a non-display region of each pixel. The light shielding film 12 prevents reflected light from entering the channel region 1 a, the source region 1 d, and the drain region 1 e of the TFT 30.
[0045]
A second interlayer insulating film 14 is laminated on the TFT 30, and an intermediate conductive layer 15 is formed on the second interlayer insulating film 14. On the intermediate conductive layer 15, the capacitor line 18 is disposed opposite to the dielectric film 17. The capacitance line 18 includes a capacitance layer and a light shielding layer, and forms a storage capacitor with the intermediate conductive layer 15 and has a light shielding function for preventing internal reflection of light. The intermediate conductive layer 15 is formed at a position relatively close to the semiconductor layer, so that irregular reflection of light can be efficiently prevented.
[0046]
A third interlayer insulating film 19 is disposed on the capacitor line 18, and a data line 6 a is stacked on the third interlayer insulating film 19. The data line 6a is electrically connected to the source region 1d through contact holes 24a and 24b penetrating the third and second interlayer insulating films 19 and 14. A pixel electrode 9a is stacked on the data line 6a with a fourth interlayer insulating film 25 interposed therebetween. The pixel electrode 9a is electrically connected to the drain region 1e through the capacitor line 18 through contact holes 26a and 26b that penetrate the fourth to second interlayer insulating films 25, 19, and 14. On the pixel electrode 9a, an alignment film 16 made of polyimide polymer resin is laminated and rubbed in a predetermined direction.
[0047]
When the ON signal is supplied to the scanning line 3a (gate electrode), the channel region 1a becomes conductive, the source region 1d and the drain region 1e are connected, and the image signal supplied to the data line 6a becomes the pixel electrode. 9a.
[0048]
On the other hand, the counter substrate 20 is provided with a first light-shielding film 23 in a region facing the data line 6a, scanning line 3a, and TFT 30 formation region of the TFT array substrate, that is, in a non-display region of each pixel. The first light shielding film 23 prevents incident light from the counter substrate 20 side from entering the channel region 1 a, the source region 1 d, and the drain region 1 e of the TFT 30. A counter electrode (common electrode) 21 is formed over the entire surface of the substrate 20 on the first light shielding film 23. An alignment film 22 made of a polyimide-based polymer resin is laminated on the counter electrode 21 and rubbed in a predetermined direction.
[0049]
A liquid crystal 50 is sealed between the element substrate 10 and the counter substrate 20. Thereby, the TFT 30 writes the image signal supplied from the data line 6a to the pixel electrode 9a at a predetermined timing. The alignment state of the molecular assembly of the liquid crystal 50 changes according to the written potential difference between the pixel electrode 9a and the counter electrode 21 to modulate light and enable gradation display.
[0050]
As shown in FIGS. 3 and 4, the counter substrate 20 is provided with a light shielding film 42 as a frame for partitioning the display area. The light shielding film 42 is formed of, for example, the same or different light shielding material as the light shielding film 23.
[0051]
A sealing material 41 that encloses liquid crystal in a region outside the light shielding film 42 is formed between the element substrate 10 and the counter substrate 20. The sealing material 41 is disposed so as to substantially match the contour shape of the counter substrate 20 and fixes the element substrate 10 and the counter substrate 20 to each other. The sealing material 41 is missing in a part of one side of the element substrate 10, and a liquid crystal injection port 78 for injecting the liquid crystal 50 is formed in the gap between the bonded element substrate 10 and the counter substrate 20. The After the liquid crystal is injected from the liquid crystal injection port 78, the liquid crystal injection port 78 is sealed with a sealing material 79.
[0052]
A data line driving circuit 61 and a mounting terminal 62 are provided along one side of the element substrate 10 in a region outside the sealing material 41 of the element substrate 10, and scanning lines are provided along two sides adjacent to the one side. A drive circuit 63 is provided. On the remaining side of the element substrate 10, a plurality of wirings 64 are provided for connecting between the scanning line driving circuits 63 provided on both sides of the screen display area. In addition, a conductive material 65 for electrically connecting the element substrate 10 and the counter substrate 20 is provided in at least one corner of the counter substrate 20.
[0053]
Next, the panel assembly process will be described. The element substrate 10 (TFT substrate) and the counter substrate 20 are manufactured separately. Polyimide (PI) to be the alignment films 16 and 22 is applied to the TFT substrate and the counter substrate 20 manufactured separately. Next, a rubbing process is performed on the alignment film 16 on the surface of the element substrate 10 and the alignment film 22 on the surface of the counter substrate 20.
[0054]
Next, a cleaning process is performed. This cleaning process is for removing dust generated by the rubbing process. When the cleaning process is completed, the sealing material 41 and the conductive material 65 (see FIG. 3) are formed. After the sealing material 41 is formed, the element substrate 10 and the counter substrate 20 are bonded together, and the pressure bonding is performed while alignment is performed, and the sealing material 41 is cured. Liquid crystal is sealed from a notch provided in a part of the sealing material 41, and the notch is closed to seal the liquid crystal.
[0055]
Next, each cell on the mother glass substrate is divided. A plurality of element substrates 10 are formed on one mother glass substrate, and each counter substrate 20 having an area smaller than that of the element substrate 10 is bonded to each element substrate 10. Therefore, the scribing process is performed on the mother glass substrate (element substrate 10) between the opposing substrates 20. The mother glass substrate is divided using the notches formed by the scribing process to obtain a liquid crystal panel composed of the element substrate 10 and the counter substrate 20 shown in FIGS.
[0056]
FIG. 1 shows a planar shape of a liquid crystal panel inspection apparatus as viewed from the upper surface side. In FIG. 1, a liquid crystal panel 82 having the same configuration as in FIGS. 3 and 4 is placed on an inspection table 81. The liquid crystal panel 82 is arranged in a direction (vertical direction) in which the incident surface is orthogonal to the horizontal direction.
[0057]
A light source device 83 is also provided on the inspection table 81 behind the liquid crystal panel 82. The light source device 83 can emit light and make it incident on the incident surface of the liquid crystal panel 82. The optical axis of the light source device 83 is generally set in the normal direction with respect to the incident surface of the liquid crystal panel 82.
[0058]
In the present embodiment, the light source device 83 is arranged on a rotating table 84 provided on the inspection table 81. The turntable 84 is rotatable on the inspection table 81 in a horizontal plane. By rotating the turntable 84, the light source device 83 can rotate the optical axis about ± 20 degrees in the horizontal plane around the normal direction with respect to the incident surface of the liquid crystal panel 82. Yes. Further, the swing angle of the light source device 83 can be changed and fixed in units of 0.5 degrees. That is, the light from the light source device 83 is incident on the incident surface of the liquid crystal panel 82 within an angle range of ± 20 ° in the horizontal plane.
[0059]
FIG. 6 is an explanatory diagram showing a specific configuration of the light source device 83 in FIG.
[0060]
As shown in FIG. 6, the light source device 83 is a two-lamp type. The lamps 101 and 102 are arranged to face each other and emit light having a predetermined wavelength, for example, light having a wavelength of about 550 nm, which is frequently used in a liquid crystal device or the like. Light from the lamps 101 and 102 enters the combining prism 103. The combining prism 103 constitutes a condensing optical system, combines the light emitted from the lamps 101 and 102, converts the light into substantially parallel light, and outputs the light to the front (on the incident surface side of the liquid crystal panel 82).
[0061]
An integrator lens 104 is disposed on the optical path of the outgoing light from the combining prism 103. The integrator lens 104 can make incident light uniform and enter the entire incident surface of the liquid crystal panel 82. For example, the integrator lens 104 can be configured by first and second lens arrays having a plurality of small lenses.
[0062]
Since the light source device 83 is configured in a two-lamp system, it can emit a sufficient amount of light for intentionally generating light leak pixel unevenness. For example, the light source device 83 is configured to be able to emit light with a brightness of an image on the screen 85 described later of 2000 lumens.
[0063]
Note that when the two-light type is adopted as the light source device, the combining prism 103 that is a condensing optical system is necessary, but the integrator lens 104 is not necessarily used.
[0064]
In FIG. 1, the liquid crystal panel 82 can rotate the incident surface within a vertical plane by a rotation mechanism (not shown) attached to the inspection table 81. Thereby, in the present embodiment, the orientation of the incident surface of the liquid crystal panel 82 can be appropriately set in association with the setting of the incident distribution of light.
[0065]
For example, when the horizontal direction of the incident surface of the liquid crystal panel 82 is made to coincide with the rotation direction of the optical axis of the light source device 83, the light leakage angle is controlled by controlling the light incident angle in the horizontal direction of the incident surface of the liquid crystal panel 82. Inspection inspection for pixel unevenness is possible. Similarly, when the vertical direction of the incident surface of the liquid crystal panel 82 is made to coincide with the direction perpendicular to the rotation direction of the optical axis of the light source device 83, light incidence in the vertical direction of the incident surface of the liquid crystal panel 82 is performed. It is possible to perform inspection determination of light leak pixel unevenness by controlling the angle.
[0066]
In the present embodiment, the turntable 84 is driven to rotate by a rotation drive unit 86. The rotation driving unit 86 is controlled by the control unit 87 to drive and control the rotation of the rotation driving unit 86, so that the optical axis of the light source device 83 is oriented in the horizontal direction, that is, incident on the incident surface of the liquid crystal panel 82. The incident distribution of light can be set as appropriate within a range of ± 20 degrees in a horizontal plane, for example.
[0067]
A screen 85 is disposed on the emission surface side of the liquid crystal panel 82 at a position separated by a predetermined distance. On the screen 85, the light emitted from the light source device 83 is projected through the liquid crystal panel 82.
[0068]
Next, the operation of the embodiment configured as described above will be described.
[0069]
First, the liquid crystal panel 82 is placed on the inspection table 81. Next, a predetermined halftone image is displayed on, for example, the entire display area of the liquid crystal panel by a liquid crystal panel drive circuit (not shown). Next, the operator operates the control unit 87 to, for example, align the optical axis of the light source device 83 in the normal direction with respect to the incident surface of the liquid crystal panel 82 as an initial state.
[0070]
The light emitted from the light source device 83 enters the incident surface of the liquid crystal panel 82, passes through the liquid crystal panel 82, and is projected on the screen 85. The image displayed by the liquid crystal panel drive circuit displays the entire screen in a predetermined halftone, and when there is no light leak pixel unevenness, the display on the screen 85 is a predetermined halftone pattern. It becomes the image of.
[0071]
Next, the operator changes the incident light distribution of the light incident on the incident surface of the liquid crystal panel 82 by the control unit 87. For example, the control unit 87 changes the optical axis of the incident light from the light source device 83 in increments of ± 1 degree or 0.5 degree with respect to the normal direction of the incident surface of the liquid crystal panel 82.
[0072]
When the optical axis of the incident light from the light source device 83 is inclined by a predetermined angle or more with respect to the normal direction of the incident surface of the liquid crystal panel 82, light leak pixel unevenness occurs. The light leak pixel unevenness is displayed in a rough pattern on the screen 85. By viewing the display on the screen 85, the operator can know the incident light distribution in which the light leak pixel unevenness occurs.
[0073]
Next, the incident surface of the liquid crystal panel 82 is rotated 90 degrees in the vertical plane. Thereby, the light incident angle in the vertical direction of the incident surface of the liquid crystal panel 82 can be changed. Thereafter, the incident light distribution in which the light leak pixel unevenness occurs in the vertical direction is inspected and determined in the same manner.
[0074]
As described above, in this embodiment, an arbitrary incident light distribution can be generated on the incident surface of the liquid crystal panel, and the relationship between the light leak pixel unevenness and the incident light distribution can be determined for each liquid crystal panel. it can. Thereby, it is possible to perform an accurate and reliable inspection for light leak pixel unevenness for each light incident condition. Therefore, by using the apparatus shown in FIG. 1 at the development and design stage, it is possible to objectively evaluate the effect of the design change in the TFT substrate and quickly feed back the design change. Further, by using the apparatus of FIG. 1 in the mass production stage, the inspection accuracy can be improved and the throughput can be increased.
[0075]
In the embodiment described above, the liquid crystal panel 82 is rotated in the vertical plane so that the light leak pixel unevenness characteristic with respect to an arbitrary direction of the incident surface of the liquid crystal panel 82 can be detected. However, for example, in the case where a panel in which light leakage pixel unevenness hardly occurs in the vertical direction is adopted as the liquid crystal panel 82, for example, the inspection determination of light leakage pixel unevenness is performed only in the horizontal direction of the incident surface of the liquid crystal panel 82. Good. Therefore, in this case, a rotation mechanism that rotates the incident surface of the liquid crystal panel 82 is not necessary.
[0076]
In this embodiment, an example in which a rotation mechanism that rotates the liquid crystal panel 82 is provided has been described. However, the light source device 83 has a configuration in which the optical axis can be changed not only in a horizontal plane but also in a vertical plane. It is clear that the same operation and effect can be obtained.
[0077]
The light source device 83 may be configured to emit parallel laser light such as helium neon. In this case, it is possible to set the incident light distribution with high accuracy. In addition, as the light incident on the incident surface of the liquid crystal panel 82 is parallel light and has a higher intensity, the steep detection of light leak pixel unevenness is possible.
[0078]
FIG. 7 is an explanatory view showing a second embodiment of the present invention. In FIG. 7, the same components as those in FIG.
[0079]
In the first embodiment, the example in which the light leak pixel unevenness is visually inspected has been described. However, in the visual inspection, determination is different for each inspector, and an objective inspection is not always performed. On the other hand, in the present embodiment, the inspection of the light leak pixel unevenness is quantified and automated to increase the inspection speed and improve the objectivity of the inspection.
[0080]
In the present embodiment, in light leak pixel unevenness, a screen display pattern peculiar to light leak pixel unevenness is registered by utilizing the fact that the screen has a rough pattern display. The relationship between the occurrence of unevenness and the distribution of incident light is quantitatively inspected and determined.
[0081]
In FIG. 7, the liquid crystal panel checker 93 drives the liquid crystal panel 82 by supplying an image signal for inspection to the liquid crystal panel 82. For example, the liquid crystal panel checker 93 generates an image signal for displaying a uniform halftone on the entire screen.
[0082]
The CCD 92 takes in an optical image of the image displayed on the screen 85, photoelectrically converts it, and outputs it as a detected image to a personal computer (personal computer) 94. When twisted nematic liquid crystal is used as the liquid crystal panel 82, the screen position at which light leak pixel unevenness easily occurs varies depending on the characteristics of the projection light from the light source device 83 and the liquid crystal twist angle and direction. Therefore, in the present embodiment, the CCD 92 captures only the screen portion where light leak pixel unevenness is likely to appear. This enables high resolution image recognition.
[0083]
Further, when the light source device 83 does not emit parallel laser light, even if the optical axis of the light source device 83 is set in the normal direction to the incident surface of the liquid crystal panel 82, the incident light The distribution has a cone-like distribution inclined at a maximum of about 6 to 7 degrees with respect to the incident surface of the liquid crystal panel 82. Therefore, the CCD 92 determines the position and size of the screen to be imaged in consideration of this point.
[0084]
The personal computer 94 detects pixel unevenness quantitatively based on an image signal from the CCD 92 using pixel unevenness quantification software.
[0085]
When the personal computer 94 performs image processing using a predetermined weighting function on the image signal from the CCD 92, the human eye projects the pattern of the image projected on the screen 85 as light leak pixel unevenness. Similar determination is possible.
[0086]
As described above, the light leak pixel unevenness results in a display with a rough pattern on the screen. Therefore, for example, it is possible to binarize the output of the CCD 92 into white (gray) and black, and determine the light leak pixel unevenness based on the area ratio and the pitch between white and black. In this case, predetermined image processing is performed so that the white and black patterns become clear. Further, by using the output of the CCD 92 with multiple gradations, the inspection accuracy can be further improved.
[0087]
In addition, for example, the personal computer 94 acquires a typical image of light leak pixel unevenness based on the results obtained by the inspection of a plurality of liquid crystal panels, digitizes this image (patterns), and obtains this pattern (light leak). It is also possible to determine the light leak pixel unevenness by a matching calculation between the pixel unevenness pattern) and the image from the CCD 92.
[0088]
In this case, the personal computer 94 stores a light leak pixel unevenness pattern in a memory (not shown), and determines the degree of light leak pixel unevenness by matching with this pattern.
[0089]
Further, as pixel unevenness, in addition to light leak pixel unevenness, electrical unevenness also exists. Therefore, the personal computer 94 sets the state in which the incident angle to the incident surface of the liquid crystal panel 82 coincides with the normal direction as an initial state, sets the output of the CCD 92 in the initial state as a reference image, and an image when the angle is shifted and the reference image Pattern recognition / comparison may be performed with respect to the difference. It can be determined that the light leak pixel unevenness does not occur in the reference image and only other pixel unevenness occurs, and the influence of the pixel unevenness other than the light leak pixel unevenness can be canceled.
[0090]
As the light source device 83, light having a wavelength (for example, 550 nm) often used in an actual liquid crystal device is used.
[0091]
Next, the operation of the embodiment configured as described above will be described with reference to FIGS. FIG. 8 is a flowchart showing the light leak pixel unevenness inspection. FIG. 9 shows the light leak pixel unevenness characteristic of a general liquid crystal panel, with the horizontal axis representing the light incident angle on the incident surface of the liquid crystal panel 82 and the vertical axis representing the nonuniformity (the degree of occurrence of light leak pixel unevenness). It is a graph.
[0092]
As shown in FIG. 9, in a general liquid crystal panel, when the incident angle on the incident surface coincides with the normal direction (0 degree), light leak pixel unevenness hardly occurs and the incident angle is about The nonuniformity rate increases rapidly around 10 degrees, and when it exceeds 10 degrees, the nonuniformity rate is saturated. Therefore, in the present embodiment, the light incident pixel unevenness is determined by changing the light incident angle from 0 degree to ± 20 degrees in steps of 0.5 degree or 1 degree. In consideration of the characteristics of the liquid crystal panel, a change in the light incident angle in the positive direction and a change in the negative direction are individually determined.
[0093]
In step S1 of FIG. 8, the control unit 91 sets the light incident angle to an initial setting of 0 degrees (normal direction with respect to the incident surface). That is, the control unit 91 controls the rotation driving unit 86 to rotate the turntable 84 so that the optical axis of the light source device 83 is aligned with the normal direction with respect to the incident surface of the liquid crystal panel 82.
[0094]
In this state, the liquid crystal panel checker 93 drives the liquid crystal panel 82 so as to obtain a predetermined halftone image. Light from the light source device 83 is modulated by the liquid crystal panel 82 and projected onto the screen 85. In this state, the CCD 92 images a predetermined position on the screen 85 by a predetermined size (step S2).
[0095]
The image picked up by the CCD 92 is transferred to the personal computer 94. In step S3, the personal computer 94 processes the input image and obtains an image pattern. If the image transferred to the personal computer 94 is a reference image, the process proceeds from step S4 to step S6, and the pattern of the reference image is stored.
[0096]
If the final angle set in step S7 has not been reached, the incident angle distribution is changed in step S8. The control unit 91 controls the rotation driving unit 86 to rotate the incident angle of light on the incident surface of the liquid crystal panel 82 by +1 degree in the positive direction, for example. The CCD 92 captures the image on the screen 85 again and outputs it to the personal computer 94.
[0097]
The personal computer 94 performs image processing in step S3 to obtain a pattern of the captured image. Next, in step S5, the captured image is corrected using the reference image, and then compared with a light leak pixel unevenness pattern stored in a memory (not shown). For example, the unevenness ratio of FIG. 9 can be obtained by comparing the patterns in step S5. The personal computer 94 stores the comparison result.
[0098]
Thereafter, the same operation is repeated, and the pattern of the captured image is compared with the optical pixel unevenness pattern while changing the incident angle of light. Thus, the degree of light leak pixel unevenness is detected for each incident angle distribution, and for example, a graph similar to the graph of FIG. 9 is created. Thus, the light leak pixel unevenness characteristic can be obtained for each liquid crystal panel.
[0099]
For example, when a graph similar to that in FIG. 9 is created, the light leak pixel unevenness characteristic in the entire measurement range can be obtained. By using this result at the development and design stage, it is possible to quickly and accurately acquire the influence on the light leak pixel unevenness due to the design change.
[0100]
Further, the characteristics of the liquid crystal panel with respect to the light leak pixel unevenness may be determined based on whether or not the level of the light leak pixel unevenness at an angle up to a predetermined light incident angle exceeds a threshold value. By using this result in the mass production stage, inspection accuracy and throughput can be improved.
[0101]
Thus, in the present embodiment, light leak pixel unevenness can be automatically detected quantitatively, and an accurate and reliable inspection for light leak pixel unevenness is possible.
[0102]
【The invention's effect】
As described above, according to the present invention, there is an effect that it is possible to perform an accurate and reliable inspection for light leak pixel unevenness for each light incident condition.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an inspection apparatus for a liquid crystal panel according to a first embodiment of the present invention.
FIG. 2 is an equivalent circuit diagram of various elements and wirings in a plurality of pixels constituting a pixel region of the liquid crystal device.
FIG. 3 is a plan view of an element substrate such as a TFT substrate as viewed from the counter substrate side together with each component formed thereon.
4 is a cross-sectional view of the liquid crystal device after the assembly process in which the element substrate and the counter substrate are bonded to each other and the liquid crystal is sealed is cut along the line HH ′ in FIG. 3;
FIG. 5 is a cross-sectional view illustrating a liquid crystal device in detail.
6 is an explanatory diagram showing a specific configuration of the light source device 83 in FIG. 1. FIG.
FIG. 7 is an explanatory diagram showing a second embodiment of the present invention.
FIG. 8 is a flowchart showing light leak pixel unevenness inspection;
FIG. 9 shows the light leak pixel unevenness characteristic of a general liquid crystal panel, with the horizontal axis representing the light incident angle on the incident surface of the liquid crystal panel 82 and the vertical axis representing the unevenness rate (the degree of occurrence of light leak pixel unevenness). Graph showing.
[Explanation of symbols]
81 ... Inspection table
82 ... LCD panel
83 ... Light source device
84 ... turntable
86: Rotation drive unit
87 ... Control unit

Claims (11)

A light source device that includes a plurality of TFTs and causes light to be incident on an incident surface of a liquid crystal panel in which a signal is given to the plurality of TFTs so as to project a predetermined image;
Incident angle control for changing the light incident angle of the light from the light source device to the incident surface of the liquid crystal panel by rotating the optical axis of the light source device within a predetermined plane perpendicular to the incident surface of the liquid crystal panel. Means,
Image acquisition means for acquiring an image by the light emitted from the liquid crystal panel;
Determination means for determining light leak pixel unevenness for each light incident angle of the light incident on the incident surface of the liquid crystal panel using the acquired image,
Comprising
The image acquisition means acquires the first image when the light incident angle is 0 degrees, acquires the second image when the light incident angle is other than 0 degrees,
The determination unit determines the light leak pixel unevenness with respect to the light incident angle when the second image is acquired using the first image as a reference for the second image.
LCD panel inspection equipment. The light source device includes a two-lamp type light emitting unit;
The liquid crystal panel inspection apparatus according to claim 1, further comprising: a condensing optical system that condenses light from the light emitting unit.   The liquid crystal panel inspection apparatus according to claim 1, further comprising a rotation mechanism that rotates the liquid crystal panel in a plane perpendicular to the optical axis of the light source device.   2. The incident angle control means makes the optical axis of the light source device rotatable in two planes that are perpendicular to each other in two predetermined planes perpendicular to the plane of incidence of the liquid crystal panel. The inspection apparatus for liquid crystal panels described in 1.   The liquid crystal panel inspection apparatus according to claim 1, wherein the light source device causes parallel light to be incident on an incident surface of the liquid crystal panel.   The liquid crystal panel inspection apparatus according to claim 1, wherein the incident angle control unit is capable of changing a light incident angle on an incident surface of the liquid crystal panel by a predetermined angle unit.   The liquid crystal panel inspection apparatus according to claim 1, wherein the incident angle control unit changes a light incident angle on an incident surface of the liquid crystal panel within a range of 0 ° to ± 20 °. The image acquisition means includes a screen on which projection light from the liquid crystal panel is projected,
The liquid crystal panel inspection apparatus according to claim 1, further comprising an imaging unit that captures an image on the screen.   The said determination means detects the said light leak pixel nonuniformity when the said 2nd image is acquired by the pattern recognition with respect to the difference of a said 1st image and a said 2nd image. The inspection apparatus for liquid crystal panels described in 1. A procedure for providing light to an incident surface of a liquid crystal panel provided with a plurality of TFTs and providing a signal to the plurality of TFTs so as to project a predetermined image;
Changing the light incident angle of the light to the incident surface of the liquid crystal panel within a predetermined plane perpendicular to the incident surface of the liquid crystal panel;
An image acquisition procedure for acquiring an image by the light emitted from the liquid crystal panel;
Using the acquired image, a determination procedure for determining light leak pixel unevenness for each light incident angle of the light incident on the incident surface of the liquid crystal panel;
Comprising
The image acquisition procedure includes a procedure of acquiring the first image when the light incident angle is 0 degrees, and a procedure of acquiring the second image when the light incident angle is other than 0 degrees. Including
The determination means determines the light leak pixel unevenness with respect to the light incident angle when the second image is acquired using the first image as a reference for the second image. Method.   The determination procedure includes a procedure of detecting the light leak pixel unevenness when the second image is acquired by pattern recognition with respect to a difference between the first image and the second image. The liquid crystal panel inspection method according to claim 11.

Images