JP4080514B2 - Inspection device, inspection method, inspection program, and computer-readable recording medium - Google Patents

Description

  The present invention relates to an apparatus for detecting the position of a display panel, and more particularly to a position detection apparatus provided in an inspection apparatus for inspecting a defect in a display panel.

  A flat panel display (hereinafter referred to as FPD) displays an image using a combination of many dots that emit light in three colors of red, blue, and green. Defects may occur in the manufacture of this FPD. There are many types of defects, including bright spot defects in which the dots always emit light, black spot defects in which the dots do not light up, and uneven defects in which the amount of light emission of many dots is not uniform. These defects are found in the inspection process for inspection, and are subject to correction and product grade setting.

  The FPD inspection process is performed at various stages of the manufacturing process. Among them, the lighting inspection step is a step of displaying an image on the FPD and inspecting for defects. This lighting inspection process consists of a process of inspecting only the plate-like panel portion to be displayed, a frame-like bezel that gives the panel strength, and a module that incorporates an electric circuit for lighting the panel. And a process of performing an inspection. Since modules are sometimes sold as parts to FPD manufacturers, the inspection process in the module state occupies an important position.

  Conventionally, in the lighting inspection of a module, a visual inspection is performed by an inspector, and the determination is made based on whether or not a defect is visible to the inspector. Since the FPD is for human viewing, even if there is a minute abnormality on the circuit, it can be said that the abnormality is not a defect if it is invisible to humans. An inspection apparatus for efficiently performing visual inspection is described in Patent Document 1, for example.

  In recent years, the size and resolution of FPDs have increased, and the need to see fine parts and the need to see a wide area has increased, and the burden of visual judgment has increased. In addition, in the determination that relies on the visual inspection of the inspector, there are problems such as oversight and variations in determination criteria, and it is difficult to perform quality control of the product.

  For this reason, FPD lighting inspection devices have been developed and put into practical use. This FPD lighting inspection apparatus displays a specific video on the FPD, images the displayed state with an imaging device, and determines the presence or absence of a defect by performing image processing on the captured image. Such an FPD lighting inspection apparatus is described in Patent Documents 2 and 3, for example.

  Many FPD lighting inspection apparatuses are inspection apparatuses that inspect an FPD only for a panel. In the panel-only inspection process, the panel is fragile, and in order to drive the panel, it is necessary to align the electrode at the end of the panel with the electrode called the contact probe, It is difficult to carry out by hand conveyance. For this reason, an automatic conveyance mechanism and a positioning mechanism are mounted in the conveyance system, and an operator has been performing a visual inspection operation while operating the mechanism unit. Therefore, when the FPD lighting inspection apparatus is introduced into the panel-only inspection process, it is not necessary to newly provide a mechanism for detecting the exact position of the panel.

  On the other hand, in the inspection process in the module state, the panel is protected by the bezel, so it is difficult to break, and in order to drive the panel, it is only necessary to insert the wiring called the harness as a connector, so the exact position Together, it was not necessary until now. Moreover, since the work of inserting the harness is difficult to automate, it was performed exclusively by workers. Further, the module has a problem that the position of the panel varies somewhat depending on the product even if the outer bezel is accurately aligned due to the accuracy of assembly of the outer bezel and the panel. Therefore, when an FPD lighting inspection device is introduced into the module inspection process, a mechanism for detecting the exact position of the panel is required.

  One method of detecting the exact position of the panel is to create an alignment mark at the edge of the panel and illuminate the alignment mark to detect the position when performing pattern inspection or exposure. It is done.

  However, when the module is inspected, the edge of the panel is hidden by the bezel, so it is necessary to create an alignment mark near the display area. Further, when detecting a bright spot defect with the FPD lighting inspection apparatus, it is required to take an image in a dark room state in which ambient light does not enter in order to pick up a slight light emission of the bright spot defect. In addition to an imaging device that detects bright spot defects, an illumination device that illuminates light of a wavelength that cannot be detected by the imaging device and an imaging device that can image with light of that wavelength are required. Therefore, it is difficult to implement the above detection method.

  As another method for detecting the correct position of the panel, there is a method of displaying an alignment mark on the panel, imaging the alignment mark, and detecting the position of the panel during panel alignment. Such a method of detecting the position and rotation angle of the display pixel of the panel is described in, for example, Patent Document 4.

  In this position detection method, an area sensor type imaging device or a line sensor type imaging device can be used as the imaging device. When an area sensor type imaging device is used, it is possible to perform imaging without changing the positional relationship between the panel and the imaging device. It can be acquired before the process and the position of the panel can be recognized.

As for the panel alignment method, when an area sensor type imaging device is used, once the positional relationship between the optical system and the panel is determined, the positional relationship does not change even if the lighting pattern is changed and imaging is performed. ,
(1) Display the alignment mark and check the position.
(2-1) Finely adjust the position of the panel and detect the position and rotation angle of the display pixel of the liquid crystal display panel,
(2-2) The method of memorizing the mark position, inspecting it as it is, and converting the coordinates in the image based on the mark position can be taken.

  However, there is no area sensor type imaging device having a sufficient number of pixels for inspecting an FPD for a large TV, and there is a problem that it is necessary to mount a plurality of cameras and the cost increases.

On the other hand, when a line sensor type imaging device is used, a high pixel image can be obtained at a lower cost than an area sensor type imaging device.
JP 2003-42959 A (published February 13, 2003) JP 2002-131180 A (published May 9, 2002) JP 2002-98651 A (published April 5, 2002) JP-A-6-250138 (published on September 9, 1994)

  However, in the above-described conventional configuration, if there is a bright spot defect in the alignment mark portion in the lighting inspection, regardless of the type of the imaging device, the defect cannot be detected, and an undetectable region is created. In order to avoid this problem, if the inspection is performed a plurality of times by changing the position of the alignment mark, there arises a problem that the tact time of the inspection is extended.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an inspection apparatus capable of detecting the bright spot defect even when the alignment mark portion has the bright spot defect, and the inspection. An object of the present invention is to provide a position detection device included in the device.

In order to solve the above-described problems, the inspection apparatus according to the present invention lights the alignment mark for lighting the alignment mark for position detection on the display panel with low luminance and luminance that is difficult to see, and the alignment mark. A position detection unit that detects the position of the display panel based on an image obtained by imaging the display panel, and the correction of the image based on the detection result of the position detection unit, and based on the corrected image And a defect detecting means for detecting a bright spot defect in the display panel .

Inspection method according to the present invention, in order to solve the above problems, there is provided an inspection method for inspecting device for inspecting the display panel based on the image of the display panel, an alignment mark for position detection A lighting control step for lighting the display panel with low luminance and a luminance that is difficult to see; a position detection step for detecting the position of the display panel based on an image obtained by imaging the display panel with the alignment mark lit ; The image correction is performed based on the detection result in the position detection step, and a defect detection step of detecting a bright spot defect in the display panel based on the corrected image is included.

  The bright spot defect is a defect in which dots having brightness higher than a reference value exist, but does not become a defect unless it is visually recognized by human eyes.

  According to the above configuration, the lighting control unit lights the alignment mark on the display panel with luminance that is difficult to see, and the position detecting unit displays the display based on an image obtained by imaging the display panel on which the alignment mark is lit. The position of the panel is detected.

Therefore , even when a dot forming an alignment mark has a bright spot defect, the brightness of the bright spot defect is higher than the brightness of the alignment mark, so that the dot can be detected as a bright spot defect. In other words, a visible bright spot defect having a brightness higher than that of the alignment mark can be detected.

  Therefore, since it is not necessary to perform the inspection a plurality of times by changing the position of the alignment mark, the inspection efficiency in the inspection apparatus can be increased.

  The lighting control means preferably lights a blue alignment mark having a luminance that is difficult to see.

  Human visual angle sensitivity is lower for blue than for green. Therefore, with the above configuration, alignment marks that are difficult to view can be easily turned on.

  The lighting control means preferably lights a red alignment mark having a luminance that is difficult to see.

  Human visual angle sensitivity is lower for red than for green. Especially in dark places, red is difficult to see. Therefore, with the above configuration, alignment marks that are difficult to view can be easily turned on.

The inspection apparatus further includes a lighting unit that lights the alignment mark on the display panel based on a signal output from the lighting control unit, and an imaging unit that images the display panel that lights the alignment mark. It is preferable to provide.

  According to the above configuration, the lighting unit lights the alignment mark on the display panel with luminance that is difficult to see under the control of the lighting control unit, and the imaging unit images the display panel with the alignment mark lit. . The position detection unit detects the position of the display panel based on the image captured by the imaging unit, and the defect detection unit corrects the captured image using the detection result of the position detection unit and the correction. A defect in the display panel is detected based on the captured image.

  Therefore, even when a dot forming the alignment mark has a bright spot defect, the presence or absence of the bright spot defect can be inspected.

  Therefore, since it is not necessary to perform the inspection a plurality of times by changing the position of the alignment mark, the inspection efficiency can be improved.

The imaging unit preferably includes a sensor having an imaging element and a moving unit that moves the sensor in a direction parallel to the surface of the display panel .

  With the above configuration, even if the display panel has a size that does not fit in the imaging area of the sensor, the entire display panel can be imaged by moving the sensor in one axial direction.

Further, an inspection program for causing a computer to function as the means of the inspection apparatus and a computer-readable recording medium on which the inspection program is recorded are also included in the technical scope of the present invention.

As described above, the inspection apparatus according to the present invention includes the lighting control means for lighting the alignment mark for position detection on the display panel with low luminance and luminance that is difficult to see, and the display panel on which the alignment mark is lit. Position detection means for detecting the position of the display panel based on the captured image, correction of the image based on the detection result of the position detection means, and the display panel based on the corrected image And a defect detection means for detecting a bright spot defect .

As described above, the inspection method according to the invention includes the lighting control step of lighting the alignment mark for position detection on the display panel with low luminance and luminance that is difficult to see, and the display panel on which the alignment mark is lit. A position detection step for detecting the position of the display panel based on the captured image, and correction of the image based on the detection result in the position detection step, and the display panel based on the corrected image And a defect detection step of detecting a bright spot defect .

Therefore , even if the dot forming the alignment mark has a bright spot defect, the dot can be detected as a bright spot defect .

  The following describes one embodiment of the present invention with reference to FIGS.

(Human visibility characteristics)
First, human visibility characteristics that are important in understanding the present invention will be described with reference to FIGS. FIG. 14 is a graph showing the emission wavelength distribution of the FPD. FIG. 15 is a graph showing human light / dark vision sensitivity characteristics. FIG. 16 is a graph showing the light receiving sensitivity characteristic when the FPD is viewed in a bright place. FIG. 17 is a graph showing the light receiving sensitivity characteristic when the FPD is viewed in a dark place. FIG. 18 is a graph showing the sensor spectral sensitivity characteristics of the CCD. FIG. 19 is a graph showing light receiving sensitivity characteristics when an FPD is imaged by a CCD.

  As shown in FIG. 14, FPD has a red (R) dot peak at 610 nm, 580 nm to 700 nm, a green (G) dot peak at 540 nm, 490 nm to 610 nm, and a blue (B) dot peak at 435 nm, 420 nm to 510 nm. The light of the wavelength is emitted.

  On the other hand, as shown in FIG. 15, human visibility is high with respect to light having a wavelength of 460 nm to 660 nm with a peak at 555 nm in photopic vision and 420 nm to 590 nm with a peak at 507 nm in dark vision. Also, as shown in FIGS. 16 and 17, the visibility of blue and red is poor in bright and dark places compared to green. In particular, red visibility is poor in a dark place.

  On the other hand, as shown in FIG. 18, the spectral sensitivity of a CCD element used in a general imaging device is high with respect to light having a wavelength from 400 nm to 950 nm with a peak at 540 nm, and all wavelengths emitted by the FPD. Can detect light. Further, as shown in FIG. 19, the light receiving sensitivity of the CCD element maintains relatively high sensitivity for blue and red as compared with visual observation.

  Therefore, in the case of photopic vision, the sensitivity of the blue dots is lower than that of the CCD element, and in the case of dark vision, the sensitivity of red dots is lower than that of the CCD element.

(Basic technical idea of the present invention)
By utilizing the difference between the light receiving sensitivity of the human eye and the light receiving sensitivity of the CCD element, the inspection apparatus of the present invention performs low brightness alignment on the display panel when detecting bright spot defects on the display panel. A mark is displayed, the position of the alignment mark is detected from an image obtained by imaging the alignment mark, and the position of the display panel is specified based on the position of the alignment mark. At this time, when the FPD product is assumed to be used in a bright place, the alignment mark is displayed with a low-brightness B dot, and in the case of an FPD product expected to be used in a dark place, it is low. An alignment mark is displayed with a luminance R dot.

  In addition, the brightness of the alignment mark is lower than the brightness (defect reference brightness) at which a dot having the same color as the alignment mark is determined to be a bright spot defect, and higher than the minimum brightness that can be detected by the imaging apparatus. The defect reference luminance is a luminance that is determined to be a bright spot defect when the luminance is higher than the luminance.

  With the above configuration, even when a dot displaying an alignment mark has a bright spot defect, the dot of the bright spot defect can be detected as a bright spot defect. Further, when a dot having a luminance lower than that of the alignment mark is present in the alignment mark, the dot is not a bright spot defect, so there is no problem.

(Configuration of the inspection apparatus 1)
Next, the configuration of the liquid crystal panel module lighting inspection apparatus 1 (hereinafter referred to as the inspection apparatus 1) of the present embodiment will be described with reference to FIGS. FIG. 1 is a functional block diagram showing the configuration of the inspection apparatus 1. FIG. 2 is a schematic diagram showing the configuration of the inspection apparatus 1. The inspection apparatus 1 detects a defect of the liquid crystal panel module 11 (display panel). In addition, the to-be-inspected object of the inspection apparatus of this invention is not limited to a liquid crystal panel module, What kind of thing may be sufficient if it is a panel for a display.

  As shown in FIGS. 1 and 2, the inspection apparatus 1 includes a lighting unit 2 (lighting unit) for displaying an image on the liquid crystal panel module 11, a TDI (Time Delay Integration) line sensor 3, and a TDI line sensor 3 (sensor). An imaging unit 5 (imaging unit) configured with a scanning stage 4 ((moving unit)), an image processing unit 6 that processes an image captured by the imaging unit 5, a lighting unit 2, an imaging unit 5, and an image processing unit 6. It is composed of a control unit 7 (lighting control means, position detection device) that drives the two in cooperation.

  In the lighting unit 2, an image (lighting inspection image) to be displayed on the liquid crystal panel module 11 is registered in advance according to the inspection contents in the inspection apparatus 1, and the lighting unit 2 is turned on according to a command from the control unit 7. An inspection image is displayed on the liquid crystal panel module 11.

  As shown in FIG. 2, the imaging unit 5 is disposed above a table (not shown) on which the liquid crystal panel module 11 is placed. The imaging axis of the TDI line sensor 3 provided in the imaging unit 5 faces downward (in the direction along the Y-axis direction in FIG. 2).

  The TDI line sensor 3 is movable along the extension direction (time integration direction) of the stage 4 (X-axis direction in FIG. 2), and the line direction of the TDI line sensor 3 is orthogonal to the extension direction of the stage 4. In the direction (Z-axis direction in FIG. 2). The liquid crystal panel module 11 is arranged so that its longitudinal direction is substantially parallel to the extending direction of the stage 4. Therefore, by scanning the TDI line sensor 3 along the stage 4, it is possible to take an image from one end of the liquid crystal panel module 11 to the other end.

  Optical components such as a lens 3 a are attached to the TDI line sensor 3. In this optical component, the magnification and the focus position are set so that the entire display surface of the liquid crystal panel module 11 can be imaged when the TDI line sensor 3 is scanned along the stage 4.

  The liquid crystal panel module 11 is carried into the inspection apparatus 1 from a factory transport apparatus (not shown) and inspected. At that time, as described above, when the TDI line sensor 3 is scanned, the liquid crystal panel module 11 is disposed at a position where the entire liquid crystal panel display surface can be imaged.

  Here, the entire surface of the liquid crystal panel display surface means an area where the entire liquid crystal panel display surface always enters even when there is an error in the loading position of the liquid crystal panel module 11 or an assembly error when the liquid crystal panel is assembled to the module. To do.

  The image processing unit 6 processes the image captured by the imaging unit 5, detects the position and inclination of the liquid crystal panel module 11, detects the presence or absence of defects in the liquid crystal panel module 11, and transmits the detection result to the control unit 7. To do. Details of the image processing unit 6 will be described later.

  The control unit 7 controls each of the above-described units, and in particular, outputs information related to luminance when displaying the lighting inspection image to the lighting unit 2.

  FIG. 3 is a perspective view showing the appearance of the inspection apparatus 1. As shown in the figure, the inspection apparatus 1 is surrounded by an outer wall 8 so that the inside thereof becomes a dark room, and the liquid crystal panel module 11 is carried in and out through an openable / closable door 9 provided on the outer wall 8. . Therefore, it is not affected by ambient light during inspection.

(Configuration of the image processing unit 6)
The configuration of the image processing unit 6 will be described with reference to FIG. FIG. 4 is a functional block diagram showing the configuration of the image processing unit 6. As shown in the figure, the image processing unit 6 includes a position detection unit 61 (position detection means, position detection device) for detecting the position of the liquid crystal panel module 11 and a defect detection unit 67 (for detecting defects in the liquid crystal panel module 11). Defect detection means).

  The position detection unit 61 detects the position of the liquid crystal panel module 11 by matching a captured image captured by the imaging unit 5 with a template image described later. The position detection unit 61 includes a memory 62, a coincidence calculation unit 63, a distance calculation unit 64, a distance determination unit 65, and a rotation angle calculation unit 66.

  The memory 62 stores template images in advance. The template image is an image obtained by capturing the liquid crystal panel module 11 displaying the alignment marks 12 in a state where there is no rotation shift. Details of the template image will be described later. The memory 62 may be provided outside the position detection unit 61.

  The coincidence calculation unit 63 performs matching between the captured image captured by the image capturing unit 5 and the template image, and calculates the coincidence between the four alignment marks in the captured image and the four alignment marks in the template image. Here, the degree of coincidence is the square of the normalized correlation (= r).

  At this time, for example, the degree of coincidence between the upper right alignment mark in the captured image and the upper right alignment mark in the template image is calculated. That is, the degree of coincidence between the closest alignment marks is calculated.

  Then, the coincidence calculation unit 63 forms an alignment mark pair configured by selecting two of the four alignment marks, and obtains the sum of the coincidence in the pair. Here, since there are six combinations for selecting two from the four alignment marks, the coincidence calculation unit 63 calculates the sum of the six coincidences.

  The distance calculation unit 64 sorts the six sums of coincidence in descending order of numerical values. Then, the pixel coordinates of the alignment marks in the template image that match the combination of the alignment marks having the largest sum of coincidence are extracted, and the pixel distance between the pixel coordinates is calculated.

  The distance determination unit 65 determines whether or not the pixel distance calculated by the distance calculation unit 64 is within a predetermined range as the distance between the alignment marks. When the pixel distance between the two alignment marks is within the range, the coordinate of the alignment mark 12 having the higher degree of coincidence is determined as the coordinate of the first alignment mark 12a, and the coordinate of the other alignment mark 12 is set to the second alignment mark. The coordinates of the mark 12b are determined (see FIG. 10 described later).

  The rotation angle calculation unit 66 determines the X and Z coordinates of the corners of the liquid crystal panel module 11 in the captured image using the coordinates of the first alignment mark 12a, and uses the coordinates of the second alignment mark 12b to set the liquid crystal panel module. 11 is calculated. A method for calculating the rotation angle θ will be described later. The rotation angle calculation unit 66 outputs the calculated value of the rotation angle θ to the panel display surface image forming unit 68 of the defect detection unit 67.

  The defect detection unit 67 includes a panel display surface image forming unit 68, a density comparison unit 69, and a defect determination unit 70.

  The panel display surface image forming unit 68 uses the value of the rotation angle θ output from the rotation angle calculating unit 66 to create a panel display surface image from the captured image captured by the imaging unit 5. Specifically, the panel display surface image forming unit 68 calculates an area in which the panel display surface in the captured image is captured from the pixel coordinates and the rotation angle θ in the captured image of the first alignment mark 12a, and the area is calculated. A panel display surface image is formed by cutting out.

  That is, the panel display surface image is an image corresponding to the area of the panel display surface of the liquid crystal panel module 11 in the captured image captured by the imaging unit 5, and is an image in which the rotation displacement of the liquid crystal panel module 11 is corrected. The panel display surface image is a defect detection image used by the density comparison unit 69.

  The density comparison unit 69 extracts pixels having a density exceeding the reference density from the panel display surface image formed by the panel display surface image forming unit 68. The reference density is a density when a bright spot defect having a defect reference brightness, which is a brightness reference value determined as a bright spot defect, is imaged, and is determined in advance by measurement.

  More specifically, the above-mentioned reference density is measured at the lowest density among the densities when an R dot bright spot defect, a G dot bright spot defect, and a B dot bright spot defect having a defect reference brightness are imaged. Is a concentration that takes into account. In the density comparison unit 69, it is detected as if it is over-detected, and the defect determination unit 70 described later re-determines.

  Here, the luminance means the value of the amount of light actually emitted from the liquid crystal panel module 11, and the density means the luminance of dots in an image obtained by imaging the liquid crystal panel module 11.

  The defect determination unit 70 determines from the coordinates of the pixel whether the pixel extracted by the density comparison unit 69 is an image of R, G, or B dots. Then, when the density of the dot is higher than the density when the dot having the same color as the dot and having the defect reference luminance is imaged, the defect determination unit 70 assumes that the pixel is an image of the bright spot defect. The defect code of the bright spot defect, the coordinates of the pixel, and the density of the pixel are stored in a memory (not shown) provided therein.

  For example, when the dot is an R dot, the defect determination unit 70 compares the density when an R dot bright spot defect having a defect reference luminance is imaged with the density of the R dot.

  As described above, the determination in two stages of the density comparison unit 69 and the defect determination unit 70 reduces the amount of processing for determining which of the RGB dots the dot having the bright spot defect is based on the pixel coordinates. And image processing can be performed at high speed.

  The defect determination unit 70 converts the coordinates of the recorded pixels of the bright spot defect into the display dot positions of the liquid crystal panel module, and transmits the result to the control unit 7.

(Display method of alignment mark 12)
Next, the display method of the alignment mark 12 in the liquid crystal panel module 11 will be described with reference to FIGS. FIG. 5 is a diagram showing a lighting inspection image 13 displayed on the liquid crystal panel module 11. FIG. 6 is a diagram illustrating a range of lighting control values for displaying the alignment mark 12.

  In the case of performing bright spot detection, when the lighting inspection image 13 displayed on the liquid crystal panel module 11 is displayed with 256 gradations for each color, the RGB value of the pixel is (0, 0, 0) as shown in FIG. To be. However, the alignment marks 12 that are alignment marks are displayed at predetermined positions near the four corners of the liquid crystal panel module 11 so that the RGB values are (0, 0, Vm).

Here, a defect reference control value Vd that lights up at a luminance equivalent to the defect reference luminance and a minimum lighting control value VL that lights up at a luminance equivalent to the lowest luminance that can be detected by the imaging unit 5 are measured in advance. . And, as shown in FIG.
VL <Vm <Vd
Is determined in advance from detection reproducibility and the like. That is, Vm is a lighting control value for the alignment mark that is larger than the lighting control value that lights at the luminance that is the lower limit value of the detection limit of the imaging unit 5 and smaller than the lighting control value that lights at the defect reference luminance.

  Vd is substantially equal to the lowest visible luminance. That is, Vd is a lighting control value for lighting at a luminance that is substantially equal to the lower limit value of the luminance at which the alignment mark 12 can be visually recognized.

  Therefore, the alignment mark 12 lit on the liquid crystal panel module 11 can be detected by the imaging unit 5 but cannot be confirmed by human eyes. That is, the alignment mark 12 is lit with a luminance that is difficult to see. Therefore, even when a dot displaying the alignment mark 12 has a bright spot defect, the dot of the bright spot defect can be detected as a defect, and a dot having a brightness lower than the brightness of the alignment mark 12 exists in the alignment mark 12. In such a case, the dot is not a bright spot defect, so this is not a problem.

  Note that the luminance that is difficult to view is the luminance that is actually determined to be a bright spot defect. The luminance that is difficult to visually recognize is set according to the delivery destination of the product and the rating of the product, and is basically a value having a correlation with visual observation. The above difficult-to-view luminance is desirably originally measured with a luminance meter or the like, but actually, the person who determines the standard visually checks the bright spot from a short distance to determine whether it should be a defect. ing.

  The luminance that is difficult to view varies depending on the contrast ratio, the screen size, the pixel size, and the number of gradations. Further, since the visual sensitivity differs depending on the hue, the luminance that is difficult to visually observe is generally different between the R picture element, the G picture element, and the B picture element.

  In addition, even if the same color filter is used with the same contrast specifications, it is difficult to see for Japanese people with relatively high sensitivity from red to yellow and for Europeans and Americans with relatively high sensitivity from green to blue. The brightness is different.

  In addition, the luminance that is difficult to view varies depending on the usage environment of the panel (brightness of the room, color tone of lighting, wall and ceiling of the room, observation distance, etc.).

  In this way, the standard for brightness that is difficult to see varies depending on each user group / environment. However, it is empirically determined that the brightness is difficult to see in the somewhat severe observer / environment that is assumed for that user group / environment. Database can be set. Alternatively, a reference deciding person with a high experience value that determines this reference may be determined by visual observation at a short distance and by judging whether or not a certain color tone appears to be a defect.

  FIG. 7 is a diagram showing the alignment mark 12 displayed on the liquid crystal panel module 11. When the alignment mark 12 is displayed on the liquid crystal panel module 11, one pixel is constituted by three dots of RGB, so as shown in FIG. ) Lights up. In the figure, an example in which the alignment mark 12 is configured by arranging nine B dots in a pyramid shape is shown, and one of the alignment marks 12 shown at the four corners of the lighting inspection image ( An area of 5 pixels in the vertical and horizontal directions (including the upper right one) is shown.

  Which dot of RGB is lit as the alignment mark 12 is based on the usage of whether the liquid crystal panel module 11 is used in a bright place or in a dark place and the above-described human visual characteristics. You only have to set it. For example, when used in a bright place, the alignment mark 12 may be displayed with B dots, and when used in a dark place, the alignment mark 12 may be displayed with R dots.

  The alignment marks 12 are respectively displayed near the four corners of the liquid crystal panel module 11, but the shape is not particularly limited. That is, the number of dots constituting the alignment mark 12 and the relative positional relationship of the dots are not particularly limited.

(Example of template image)
The position detection unit 61 matches the template image with a region having a size in which the alignment mark 12 is inserted even if the position of the liquid crystal panel module 11 is shifted from the four corners of the captured image captured by the imaging unit 5 to the maximum extent.

  FIG. 8 shows a template image 14 when one pixel is imaged with a resolution of 3 × 3 as an example of the template image. In the same figure, only the upper right part (vertical and horizontal 15 pixels) of the template image 14 including the region where the alignment mark 12 is imaged is shown. In the template image 14, one dot is displayed by 3 pixels of the image sensor. Note that the resolution of the template image is not particularly limited as long as it can capture each dot individually.

(Flow of position detection processing in the position detector 61)
Next, the flow of position detection processing in the position detection unit 61 will be described with reference to FIGS.

  FIG. 9 is a flowchart showing the flow of processing in the position detection unit 61. First, the degree-of-matching calculation unit 63 calculates the degree of matching of the template matching at the four corners, and calculates the sum of the degree of matching of the two corners selected from the four corners (S1). Here, since there are six combinations for selecting two corners from the four corners, the coincidence calculation unit 63 calculates the sum of these six coincidences. The coincidence calculation unit 63 outputs the calculated sum of the coincidence values to the distance calculation unit 64.

  When receiving the value of the sum of coincidences, the distance calculating unit 64 sorts the six sums of coincidences in descending order of numerical values. Then, the pixel coordinates of the alignment mark 12 in the template image 14 that match the combination of the alignment marks 12 having the largest sum of coincidences are extracted, and the pixel distance between the pixel coordinates is calculated (S2). The distance calculation unit 64 outputs the calculated pixel distance value to the distance determination unit 65.

  When receiving the value of the pixel distance, the distance determination unit 65 determines whether or not the pixel distance is within a range predetermined as the distance between the alignment marks 12. If the pixel distance is not within the predetermined range (NO in S3), collation is performed with a combination of alignment marks 12 having the next highest sum of coincidence as a template matching error.

  If all of the six combinations exceed the predetermined range (YES in S4), distance determination unit 65 outputs error information indicating that template matching has failed to control unit 7 (S5). .

  When the pixel distance between the two alignment marks 12 is within a predetermined range (YES in S3), the distance determination unit 65 determines the coordinates of the alignment mark 12 with the higher degree of coincidence as the first alignment mark 12a. The coordinates of the other alignment mark 12 are used as the coordinates of the second alignment mark 12b, and both coordinates are output to the rotation angle calculation unit 66 (S6).

  FIG. 10 is a diagram for explaining a method for detecting a region obtained by imaging the display surface of the liquid crystal panel module from a captured image.

  As shown in the figure, since the imaging resolution of the imaging unit 5 is fixed and the size of the liquid crystal panel module 11 to be imaged is also known, the orientation of the liquid crystal panel module 11 in the captured image 16 is the X direction, Z It has three degrees of freedom of direction and rotation in the XZ plane. Therefore, when the coordinates are received, the rotation angle calculation unit 66 uses the coordinates (x, y) of the first alignment mark 12a to detect the corners of the panel display surface area 15 that is an area where the liquid crystal panel module 11 is imaged. The X and Z coordinates are determined, and the rotation angle θ of the panel display surface area 15 with respect to the captured image 16 is calculated using the coordinates of the second alignment mark 12b (S7). The rotation angle calculation unit 66 outputs the calculated value of the rotation angle θ to the panel display surface image forming unit 68 of the defect detection unit 67.

  Note that the distance calculation unit 64 may calculate the pixel distance only for the sum of the six matching degrees having the largest matching degree.

(Flow of defect detection processing in the defect detection unit 67)
Next, the flow of the defect detection process in the defect detection unit 67 will be described with reference to FIGS. FIG. 11 is a flowchart showing the flow of processing in the defect detection unit 67.

  First, when the value of the rotation angle θ is received from the rotation angle calculation unit 66, the panel display surface image forming unit 68 uses the value of the rotation angle θ to generate a panel display surface from the captured image 16 captured by the imaging unit 5. An image 17 is created (S21).

  FIG. 12 is a diagram illustrating a panel display surface image 17 cut out from the captured image 16. As shown in FIG. 12, since the panel display surface image 17 is obtained by correcting the inclination of the panel display surface region 15 using the value of the rotation angle θ, each side of the panel display surface image 17 is subjected to defect detection. It is parallel to the Xi axis or the Zi axis, which is the coordinate axis for the image for use.

  The panel display surface image forming unit 68 outputs the created panel display surface image 17 to the density comparison unit 69.

  When the panel display screen image 17 is received, the density comparison unit 69 extracts, from the panel display screen image 17, pixels having a density exceeding a reference density that is a reference value of density determined to be a luminance defect (S22). The extracted pixel information is output to the defect determination unit 70.

  When the pixel information is received, the defect determination unit 70 determines from the pixel coordinates whether the extracted pixel is an image of R, G, or B, and determines whether it is a defect (S23). .

  Specifically, if the pixel is an area in which an R dot is imaged, the defect determination unit 70 determines that the pixel has an R dot brightness when the density is higher than the density at which an R dot bright spot defect with a defect reference brightness is imaged. It is determined that the point defect has been imaged, and the defect code of the R dot luminescent spot defect, the coordinates of the pixel, and the density of the pixel are stored in a memory (not shown) included in the pixel itself.

  In addition, if the pixel is an area in which a G dot is imaged, the defect determination unit 70 determines that the pixel has a G dot luminescent spot defect if the density is higher than the density at which the G dot luminescent spot defect with the defect reference luminance is imaged. It is determined that the image is taken, and the defect code of the G dot luminescent spot defect, the coordinates of the pixel, and the density of the pixel are stored.

  In addition, if the pixel is an area in which a B dot is imaged, the defect determination unit 70 determines that the pixel has a B dot luminescent spot defect if the density is higher than the density at the time of imaging a B dot luminescent spot defect with a defect reference luminance. It is determined that the image is taken, and the defect code of the B dot luminescent spot defect, the coordinates of the pixel, and the density of the pixel are stored.

  Regarding the dots constituting the alignment mark 12, since the alignment mark 12 is lit at the reference brightness of the B dot, even if the dot constituting the alignment mark 12 has a B dot bright spot defect, the B dot Bright spot defects can be detected. In that case, the defect determination unit 70 determines that the pixel that has captured the dot is the one that has captured the B dot bright spot defect, the defect code of the B dot bright spot defect, the coordinates of the pixel, and the density of the pixel. Remember.

  The defect determination unit 70 converts the stored coordinates of the pixel of the bright spot defect into the position of the display dot of the liquid crystal panel module 11, and transmits it to the control unit 7.

(Processing flow in the inspection apparatus 1)
The flow of processing in the inspection apparatus 1 will be described with reference to FIG. FIG. 13 is a flowchart showing the flow of processing in the inspection apparatus 1. The operations of the imaging unit 5, the image processing unit 6, the lighting unit 2, and the like are performed according to instructions from the control unit 7.

  The inspection device 1 stands by with the imaging unit 5 moved to a position where it does not interfere with the loading of the liquid crystal panel module 11 and the door 9 is open.

  When the transport device (not shown) carries the liquid crystal panel module 11 into the inspection device 1, the door 9 is closed and the interior of the inspection device 1 becomes a dark room (S31).

  Then, the wiring between the lighting unit 2 and the liquid crystal panel module 11 is connected, and the driving of the liquid crystal panel module 11 is started (S32).

  Then, a lighting inspection image corresponding to the inspection item of the liquid crystal panel module 11 is displayed on the liquid crystal panel module 11 by the lighting unit 2 (lighting control step) (S33). At this time, the control unit 7 outputs the lighting control value (Vm) to the lighting unit 2 so that the luminance of the alignment mark 12 is difficult to see.

  The imaging unit 5 scans the TDI line sensor 3 over the entire liquid crystal panel display surface at a constant speed, and the TDI line sensor 3 images the entire liquid crystal panel display surface (S34). The speed at this time is determined in advance by the driving frequency of the liquid crystal panel, the sensitivity of the TDI line sensor 3, the integration time for time integration, the imaging resolution, and the capability of the stage 4. An image captured by the TDI line sensor 3 is transmitted to the image processing unit 6.

  When the captured image is received, the image processing unit 6 detects the position of the liquid crystal panel module 11 based on the captured image (position detection step) (S35).

  Then, the image processing unit 6 detects the presence / absence of a defect based on the panel display surface image 17 whose position has been corrected (S36), and transmits the detection result to the control unit 7.

  When there are a plurality of inspection items of the liquid crystal panel module 11, an image corresponding to the inspection item is displayed on the liquid crystal panel module 11 by the lighting unit 2. The imaging unit 5 captures each displayed image, and the image processing unit 6 repeats the process of detecting the presence or absence of a defect based on each captured image and transmitting the detection result to the control unit 7.

  When all the inspection items are completed, the driving of the liquid crystal panel module 11 is stopped, and the wiring between the lighting unit 2 and the liquid crystal panel module 11 is disconnected (S37).

  Then, the imaging unit 5 moves to a position that does not hinder the carry-out of the liquid crystal panel module 11, the door 9 is opened, and the liquid crystal panel module 11 is carried out by the transport device (S38).

  The controller 7 determines the quality of the liquid crystal panel module 11 by integrating the inspection results received from the image processor 6 (S39). Inspection is performed in this way.

(Effect of inspection device 1)
As described above, the inspection apparatus 1 uses the fact that the visual spectral sensitivity is different from the spectral sensitivity characteristic of the TDI line sensor 3, and pays attention to the blue wavelength having a higher spectral sensitivity of the TDI line sensor 3 than the visual inspection. The coordinates of the liquid crystal panel module 11 are specified by displaying the blue alignment mark 12 of luminance on the liquid crystal panel module 11.

  The shape of the alignment mark 12 is set in advance so as not to misrecognize bright spot defects or noise, and template matching is performed on the region where the alignment mark 12 is supposed to be present, so that the alignment mark 12 is obtained from the captured image. Recognize

  The predetermined luminance for displaying the alignment mark 12 is set so as to be a recognizable density value in an image captured by the TDI line sensor 3 although it cannot be recognized visually.

  With this configuration, the liquid crystal panel module 11 can be mounted on the inspection apparatus 1 with a positional accuracy of about ± 5 mm due to mechanical accuracy even without a special alignment mechanism. By displaying the alignment mark 12 in the position, it is possible to recognize where the display portion of the liquid crystal panel module 11 is in the captured image.

  In addition, if there is a bright spot defect with brightness greater than or equal to a predetermined brightness on the alignment mark 12, detection is possible, and if there is a bright spot defect with a brightness lower than the predetermined brightness of the alignment mark 12, detection is not possible. Although it is possible, since the defect is not visible, even if it cannot be detected, it does not become a defective product.

  In the case where the light is turned on white and a black spot defect is detected, the display area can be specified by using the edge part of the lighted white without needing to display the alignment mark 12.

(Example of change)
In the above configuration, the alignment mark 12 is formed by B dots, but may be formed by R dots. In that case, the luminance of the R dots forming the alignment mark 12 may be set to be difficult to view in consideration of the red visual characteristic. In the above configuration, the lighting inspection image is registered in the lighting unit 2. However, it may be registered in the control unit 7.

  Further, the control unit 7 and the position detection unit 61 may be realized on a single semiconductor chip to form a position detection device.

  Further, the line sensor included in the imaging unit 5 is not limited to the TDI line sensor 3 and may be any line sensor. Furthermore, the imaging unit 5 may include an area sensor.

  The position detection method in the position detection unit 61 is preferably the above-described one, but may not be the one described above.

  Each block of the inspection apparatus 1 described above, in particular, the image processing unit 6 and the control unit 7 may be configured by hardware logic, or may be realized by software using a CPU as follows.

  That is, the inspection apparatus 1 includes a CPU (central processing unit) that executes instructions of a control program that realizes each function, a ROM (read only memory) that stores the program, a RAM (random access memory) that expands the program, A storage device (recording medium) such as a memory for storing the program and various data is provided. The object of the present invention is to record the program code (execution format program, intermediate code program, source program) of the control program (position detection program) of the inspection apparatus 1 which is software that realizes the above-described functions so that it can be read by a computer. This can also be achieved by supplying the recording medium to the inspection apparatus 1 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include tapes such as magnetic tapes and cassette tapes, magnetic disks such as floppy (registered trademark) disks / hard disks, and disks including optical disks such as CD-ROM / MO / MD / DVD / CD-R. Card system such as IC card, IC card (including memory card) / optical card, or semiconductor memory system such as mask ROM / EPROM / EEPROM / flash ROM.

  Further, the inspection apparatus 1 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication. A net or the like is available. Also, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

  Further, the present invention can be expressed as follows.

The position detection apparatus of the present invention includes a lighting control means for lighting an alignment mark for position detection on a display panel with a luminance that is difficult to see, and the display based on an image obtained by imaging the display panel on which the alignment mark is lit. Position detecting means for detecting the position of the panel.

  The position detection method of the present invention is a position detection method in a position detection device for detecting the position of a display panel, and a lighting control step of lighting an alignment mark for position detection on the display panel with a luminance that is difficult to see And a position detection step of detecting the position of the display panel based on an image obtained by imaging the display panel with the alignment mark turned on.

The inspection apparatus of the present invention is an inspection apparatus that inspects the display panel based on the image of the display panel, and is a signal for lighting the alignment mark for position detection on the display panel with a luminance that is difficult to see. Based on a signal from the lighting control means, a lighting means for lighting the alignment mark on the display panel, an imaging means for imaging the display panel with the alignment mark lit, and the imaging A position detecting unit for detecting the position of the display panel based on a captured image captured by the unit; and correcting the captured image based on a detection result of the position detecting unit; and based on the corrected captured image Defect detecting means for detecting a bright spot defect in the display panel.

  The inspection apparatus includes a lighting device that lights a display device, an imaging device that images the display device, and an image processing device that performs image processing on the captured image, and an apparatus that inspects image quality with the display device turned on. A lighting device capable of displaying an alignment mark on a display device with luminance and color that cannot be captured by human vision, and an imaging device capable of imaging the alignment mark are provided.

  Moreover, in the said inspection apparatus, it is preferable that the display method of an alignment mark is what displays by the brightness | luminance which cannot be caught by human vision using a blue dot.

  Moreover, in the said inspection apparatus, it is preferable that the display method of an alignment mark is what displays by the brightness | luminance which cannot be perceived by human vision using a red dot.

  In addition, it is preferable that the imaging apparatus includes a TDI line sensor and a moving stage, and performs imaging by moving the imaging apparatus in a uniaxial direction relative to the display apparatus.

  It should be noted that the present invention is not limited to the above-described embodiment, and various modifications are possible within the scope shown in the claims, and an implementation obtained by appropriately combining technical means disclosed in the embodiment. The form is also included in the technical scope of the present invention.

  Even when there is a bright spot defect in the alignment mark portion, the bright spot defect can be detected, so that it can be used as an inspection apparatus for a display panel such as a liquid crystal panel or a position detection apparatus provided in the inspection apparatus.

It is a functional block diagram which shows the structure of the test | inspection apparatus of one Embodiment. It is the schematic which shows the structure of the test | inspection apparatus of one Embodiment. It is a perspective view which shows the external appearance of the test | inspection apparatus of one Embodiment. It is a functional block diagram which shows the structure of the image process part with which the inspection apparatus of one Embodiment is provided. It is a figure which shows the image for lighting test | inspection displayed on a liquid crystal panel module. It is a figure which shows the range of the lighting control value which displays an alignment mark. It is a figure which shows the alignment mark displayed on the liquid crystal panel module. It is a figure which shows an example of a template image. It is a flowchart which shows the flow of a process in the position detection part with which an image process part is provided. It is a figure explaining the method to detect the area | region which imaged the display surface of the liquid crystal panel module from the captured image. It is a flowchart which shows the flow of the process in a defect detection part. It is a figure which shows the panel display surface image cut out from the captured image. It is a flowchart which shows the flow of the process in the test | inspection apparatus of one Embodiment. It is a graph which shows distribution of the emission wavelength of FPD. It is a graph which shows the human night vision sensitivity characteristic. It is a graph which shows the light reception sensitivity characteristic at the time of seeing FPD in a bright place. It is a graph which shows the light reception sensitivity characteristic at the time of seeing FPD in the dark place. It is a graph which shows the sensor spectral sensitivity characteristic of CCD. It is a graph which shows the light reception sensitivity characteristic at the time of imaging FPD with CCD.

Explanation of symbols

1 LCD panel module lighting inspection device (inspection device)
2 lighting part (lighting means)
3 TDI line sensor (sensor)
4 Stage (moving means)
5 Imaging unit (imaging means)
6 Image processing unit 7 Control unit (lighting control means, position detection device)
11 Liquid crystal panel module (display panel)
12 Alignment Mark 12a First Alignment Mark 12b Second Alignment Mark 61 Position Detection Unit (Position Detection Unit, Position Detection Device)
67 Defect detection unit (defect detection means)

Claims (8)

Lighting control means for lighting an alignment mark for position detection on the display panel with low luminance and luminance that is difficult to see;
Position detecting means for detecting the position of the display panel based on an image obtained by imaging the display panel with the alignment mark turned on ;
An inspection apparatus comprising: defect detection means for correcting the image based on a detection result of the position detection means, and detecting a bright spot defect in the display panel based on the corrected image. . The inspection apparatus according to claim 1, wherein the lighting control unit lights a blue alignment mark having a luminance that is difficult to view. The inspection apparatus according to claim 1, wherein the lighting control unit lights a red alignment mark having a luminance that is difficult to view. Based on the signal output by the lighting control means, lighting means for lighting the alignment mark on the display panel;
  The inspection apparatus according to claim 1, further comprising imaging means for imaging the display panel on which the alignment mark is lit. The inspection apparatus according to claim 4, wherein the imaging unit includes a sensor having an imaging element and a moving unit that moves the sensor in a direction parallel to the surface of the display panel . An inspection method in an inspection apparatus for inspecting the display panel based on an image of the display panel ,
A lighting control process for lighting the alignment mark for position detection on the display panel with low luminance and luminance that is difficult to see,
A position detection step for detecting the position of the display panel based on an image obtained by imaging the display panel with the alignment mark lit ;
It performs correction based on the image of the detection result of the position detecting step, inspecting method characterized by based on the corrected image and a defect detection step of detecting a luminance point defect in the display panel . The inspection program for functioning a computer as said each means of the inspection apparatus of Claims 1-3. A computer-readable recording medium on which the inspection program according to claim 7 is recorded.

Images