JP5012480B2 - Plasma display panel inspection apparatus and inspection method - Google Patents

Description

  The present invention relates to an inspection apparatus and an inspection method for a plasma display panel used for a wall-mounted television or a large monitor, and relates to a technique for inspecting a display defect of a plasma display panel at high speed and with high accuracy.

  In recent years, the number of plasma display devices produced has been dramatically improved. Along with this, establishment of a technique for inspecting the image display quality of a plasma display panel (hereinafter abbreviated as “panel”) in a short time is demanded in production sites.

As a panel display defect, for example, there is a pixel defect due to a lighting defect, and an inspection apparatus and an inspection method for detecting such a display defect have been proposed (for example, see Patent Document 1). In Patent Document 1, the panel is turned on, the screen of the lit panel is captured by an imaging camera, the captured image is taken into an image processing apparatus, and defects and display unevenness of pixel cells of the display panel are detected by the image processing apparatus. It is described that the determination is made by quantification.
JP-A-9-218131

  In recent years, image display quality required for plasma display devices has been increasing. On the other hand, the panel has a display defect that occurs only when a specific gradation is displayed. In order to detect such a display defect, it is necessary to perform inspections for all gradations. In such a case, the time required for the inspection becomes enormous. That is, it is required to automatically detect a display defect that occurs only when displaying a specific gradation and is difficult to detect by a conventional inspection method with high speed and high accuracy.

  The present invention has been made to meet such a demand, and can automatically detect a display defect that occurs only when displaying a specific gradation with high speed and high accuracy. It is an object to provide an inspection apparatus and an inspection method.

  In order to achieve the above object, a panel inspection apparatus of the present invention includes a panel driving unit that displays an inspection pattern image whose gradation changes at a predetermined time interval on the panel, and an image display surface of the panel. From an imaging unit that captures images at a time interval corresponding to the time interval, a change amount calculation unit that calculates a luminance change amount between inspection images by comparing a plurality of inspection images captured by the imaging unit, and a change amount calculation unit A feature for determining whether or not the obtained luminance change amount is within a predetermined range, extracting a region outside the predetermined range, and calculating a feature amount of the region extracted by the region extraction unit It is characterized by comprising an amount calculation unit and a pass / fail determination unit for determining pass / fail of the panel based on the feature amount obtained from the feature amount calculation unit.

  With such a configuration, it is possible to determine whether the panel is good or bad based on the amount of change in luminance between the captured inspection images, so that the abnormal lighting or non-lighting occurs only when a specific gradation is displayed. It is possible to automatically detect a defective cell, which is normally lit when displaying gradation, and which is difficult to detect with the conventional technique, at high speed and with high accuracy.

In addition, the panel inspection apparatus of the present invention includes a maximum value detection unit that detects a maximum change amount that is the maximum value of the luminance change amount and a minimum value detection unit that detects a minimum change amount that is the minimum value of the luminance change amount. The region extraction unit is configured to set a predetermined minimum value for a region where the maximum change detected by the maximum value detection unit is larger than a predetermined maximum value threshold and a minimum change detected by the minimum value detection unit. A region that is smaller than the threshold value may be extracted, and the feature amount calculation unit may determine the presence or absence of the region extracted by the region extraction unit and output the determination result as a feature amount . As a result, the number of pass / fail determinations can be reduced, so that inspection can be performed at higher speed.

  Further, the panel inspection apparatus of the present invention may be configured such that the change amount calculation unit calculates the luminance change amount each time an inspection image is captured. As a result, the amount of image data that must be stored can be greatly reduced.

  In the panel inspection method of the present invention, an inspection pattern image whose gradation changes at a predetermined time interval is displayed on the panel, and an image display surface of the panel is captured at a time interval corresponding to the predetermined time interval described above. A plurality of captured inspection images are compared with each other to calculate a luminance change amount between the inspection images, determine whether the luminance change amount is within a predetermined range, And calculating the feature quantity of the above-described area, and then determining whether the panel is good or bad based on the feature quantity.

  As a result, it is possible to determine whether the panel is good or bad based on the amount of change in brightness between the captured inspection images. Therefore, abnormal lighting or non-lighting occurs only when a specific gradation is displayed. It is possible to automatically detect a defective cell that is normally lit when displayed and difficult to detect with the conventional technology at high speed and with high accuracy.

  According to the present invention, it is possible to provide an inspection apparatus and an inspection method for a plasma display device that automatically detect high-precision and high-speed even when a display defect occurs only when displaying a specific gradation. Become.

  Hereinafter, an inspection apparatus according to an embodiment of the present invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is an exploded perspective view showing the main part of the panel according to Embodiment 1 of the present invention. The panel 10 is configured such that a glass front substrate 21 and a rear substrate 31 are arranged to face each other and a discharge space is formed therebetween. On the front substrate 21, a plurality of scanning electrodes 22 and sustaining electrodes 23 constituting the display electrode pair 28 are formed in parallel with each other. A dielectric layer 24 is formed so as to cover the scan electrodes 22 and the sustain electrodes 23, and a protective layer 25 is formed on the dielectric layer 24. A plurality of data electrodes 32 are formed on the rear substrate 31 in parallel. An insulating layer 33 is formed so as to cover the data electrode 32, and a grid-like partition wall 34 is provided on the insulating layer 33. A phosphor layer 35 is provided on the surface of the insulator layer 33 and the side surfaces of the partition walls 34. The front substrate 21 and the rear substrate 31 are arranged to face each other so that the scan electrode 22 and the sustain electrode 23 and the data electrode 32 intersect each other, and in the discharge space formed therebetween, for example, neon And a mixed gas of xenon. Note that the structure of the panel is not limited to the above-described structure, and for example, a structure having a stripe-shaped partition may be used.

  FIG. 2 is an electrode array diagram of panel 10 used in the first exemplary embodiment of the present invention. N scanning electrodes 22 and n sustaining electrodes 23 are arranged in the row direction, and m data electrodes 32 are arranged in the column direction. A discharge cell is formed at a portion where a pair of scan electrode and sustain electrode intersects with one data electrode, and m × n discharge cells are formed in the discharge space.

  Next, the inspection apparatus according to the present embodiment that inspects the panel 10 configured as described above will be described.

  FIG. 3 is a circuit block diagram of the inspection apparatus 40 according to Embodiment 1 of the present invention. The inspection apparatus 40 that inspects the panel 10 includes a panel inspection table 41 on which the panel 10 is installed, a panel driving unit 42 that displays the inspection pattern image on the panel 10 by driving the panel 10, and an image display surface of the panel 10. And an image processing unit 44 that performs signal processing of an image signal output from the imaging unit 43. As described above, the inspection apparatus 40 displays the inspection pattern image on the panel 10 that is a display unit of the image display apparatus, images the image display surface of the panel 10, and uses the image captured by the imaging to use the panel. This is an inspection apparatus that performs 10 inspections.

  The panel drive unit 42 generates an inspection pattern signal for an inspection pattern image to be displayed on the panel 10 and causes the panel 10 to display the inspection pattern image. This inspection pattern image is an image in which the gradation value changes at a predetermined time interval, and the display gradation is the first floor simultaneously from the gradation value 0 of the minimum gradation value to the gradation value 255 of the maximum gradation value. It is a pattern that increases gradually. Here, it is assumed that one gradation is increased for each field. Accordingly, when 60 fields are displayed per second, it takes about 4.27 seconds from the start of display of the inspection pattern image to the end of display.

  The imaging unit 43 captures the panel 10 on which the inspection pattern image is displayed at a time interval (here, for each field) corresponding to a change in the gradation value in the inspection pattern image, and displays the entire display image (here, the floor). 256 images from gradation value 0 to gradation value 255) are taken in as inspection images. The inspection image captured by the imaging unit 43 is supplied to the image processing unit 44 as inspection image data. In order to perform such processing, the imaging unit 43 controls one or a plurality of cameras 50 that capture the image display surface of the panel 10 and the imaging of the camera 50, and performs AD conversion on the output signal of the camera 50. And an imaging control unit 51 that generates inspection image data by performing signal processing such as the above. In the present embodiment, it is assumed that the camera 50 captures an image for each field in accordance with a change in gradation value in the inspection pattern image. Therefore, each image data of continuous images obtained from the camera 50 has a data value corresponding to the light emission luminance of each discharge cell of the panel 10.

  The image processing unit 44 includes an image storage unit 52 that stores inspection image data corresponding to a plurality of inspection images, a change amount calculation unit 53 that calculates a change amount of luminance between inspection images for each inspection image, and a change amount. It is determined whether or not the luminance change amount obtained from the calculation unit 53 is within a predetermined range, and an area extraction unit 54 that extracts an area on the inspection image that is outside the predetermined range, and an area extracted by the area extraction unit 54 A feature amount calculation unit 55 that calculates a feature amount, and a quality determination unit 56 that determines the quality of the panel 10 according to the feature amount obtained from the feature amount calculation unit 55 are provided.

  In the image processing unit 44, the image storage unit 52 stores image data of a plurality of (in this case, 256) inspection images that the imaging unit 43 has continuously captured in units of a predetermined period (here, for each field). Remember.

  The change amount calculation unit 53 uses the inspection image data stored in the image storage unit 52 to calculate a luminance change amount in units of pixels for each inspection image. Specifically, the image data of the inspection image of interest is compared with the image data of the inspection image captured immediately before and immediately thereafter, and the amount of change in luminance is calculated for each pixel.

  For example, in the image data captured nth in the image storage unit 52, if the image data for the pixel Cij of the camera 50 (i, j: an integer indicating the position of the pixel of the camera 50) is Dij (n), the luminance change The amount ΔDij (n) is calculated based on the following equation corresponding to the second order differential operation.

ΔDij (n) = (Dij (n) × 2-Dij (n + 1) −Dij (n−1)) / 2
In this manner, the change amount calculation unit 53 generates difference image data representing the luminance change amount between the inspection images.

  Here, the luminance change of the image data taken into the inspection apparatus 40 will be described. FIG. 4 is a diagram illustrating an example of a luminance change in a discharge cell having 256 image data captured by the inspection apparatus 40 according to the first embodiment of the present invention. 4 (a) shows the change in luminance in a discharge cell that lights normally, FIG. 4 (b) shows the change in luminance in a discharge cell that lights abnormally at a specific gradation, and FIG. 4 (c) shows a change in luminance at a specific gradation. The luminance change in the discharge cell that becomes the lamp is shown. 4A to 4C, the horizontal axis represents time, and the vertical axis represents emission luminance. When an image pattern in which the display gradation increases from gradation value 0 to gradation value 255 by one gradation as described above is displayed on the panel 10, the discharge cells in the panel 10 are normally lit discharge cells. As shown in FIG. 4A, the emission luminance of the discharge cells (here, the image data in the inspection image taken by the camera 50) increases uniformly. In contrast, in a discharge cell that is abnormally lit at a specific gradation, as shown in FIG. 4B, the emission luminance of the discharge cell is an abnormal value (for example, gradation value 255) at the specific gradation. Further, in a discharge cell that is not lit at a specific gradation, as shown in FIG. 4C, the emission luminance of the discharge cell becomes an abnormal value (for example, gradation value 0) in the specific gradation.

  FIG. 5 is a diagram illustrating an example of the luminance change amount calculated by the change amount calculation unit 53 of the inspection apparatus 40 according to Embodiment 1 of the present invention. 5 shows the time change of the luminance change amount in the discharge cell used in FIG. 4, and FIG. 5 (a) shows the time change of the luminance change amount in the discharge cell normally lit. ) Shows the time change of the luminance change amount in the discharge cell abnormally lit at the specific gradation, and FIG. 5C shows the time change of the luminance change amount in the discharge cell which becomes unlit at the specific gradation. In FIGS. 5A to 5C, the horizontal axis represents time, and the vertical axis represents the luminance change amount.

  In the case of a discharge cell that is normally lit, as shown in FIG. 4A, the emission luminance of the discharge cell increases uniformly, so that the amount of change in luminance is almost as shown in FIG. A constant and small value (here, the gradation value 1 is equivalent). In contrast, as shown in FIG. 4B, in the discharge cell that is abnormally lit in a specific gradation, the luminance change amount shows a large positive value in the specific gradation as shown in FIG. 5B. . Further, in the discharge cell that is not lit at a specific gradation as shown in FIG. 4C, the luminance change amount has a large negative value at the specific gradation as shown in FIG. 5C. Show.

  In this way, discharge cells that are abnormally lit or not lit only when displaying a specific gradation are normally lit when displaying other gradations, but are difficult to detect with the prior art. By using the inspection apparatus 40 shown in the embodiment, these defective cells can be detected at high speed and with high accuracy.

  Next, the region extraction unit 54 determines whether the luminance change amount calculated by the change amount calculation unit 53 is within a predetermined range set in advance, and extracts a region on the inspection image that is outside the predetermined range. To do. Specifically, the calculated difference image data is compared with a plurality of preset threshold values (upper threshold value and lower threshold value), and the difference image data is compared with the upper threshold value and the lower threshold value. It is determined whether or not it is within the predetermined range set in step (b), and an area where pixels having pixel data outside the range are present is extracted. Note that the region extracting unit 54 may be configured to compare the absolute value of the luminance change amount with one threshold value.

  The feature amount calculation unit 55 calculates the feature amount (for example, area) of the region extracted by the region extraction unit 54. This area can be calculated, for example, by calculating the total number of pixels in the extracted region in the target inspection image.

  The quality determination unit 56 determines the quality of the panel 10 by comparing the feature amount extracted by the feature amount calculation unit 55 with a predetermined determination criterion. For example, the pass / fail determination unit 56 determines whether the area of the extracted region exceeds a predetermined threshold value. When it exceeds a predetermined threshold value, it is determined as non-conforming, and when it is below the predetermined threshold value, it is determined as conforming.

  FIG. 6 is a flowchart for explaining the operation of the inspection apparatus 40 according to Embodiment 1 of the present invention.

  First, as shown in FIG. 6, the panel drive unit 42 displays an inspection pattern image on the panel 10 (step S1).

  Next, the inspection apparatus 40 captures the display image on the panel 10 with the camera 50 (step S2). Then, the inspection apparatus 40 stores inspection image data (hereinafter simply referred to as “image data”) captured by imaging in the image storage unit 52 (step S3). At this time, if the number n of image data stored in the image storage unit 52 is less than the predetermined number N (N = 256 in the present embodiment), the process returns to step S1, and the inspection apparatus 40 sets n = N. Repeat the imaging until. On the other hand, if the number n of stored image data is N, the process proceeds to the next step (step S4). As described above, in step S1 to step S4, the inspection pattern image displayed on the panel 10 is captured for each gradation, and N images are captured as inspection images.

  Next, in the image processing unit 44, the change amount calculation unit 53 sets the image data for N sheets stored in the image storage unit 52 in the order in which the image data is captured and the image data before and after the image data is captured. In comparison, the luminance change amount of each pixel is calculated (step S5).

  Next, the region extraction unit 54 compares whether the luminance change amount calculated in step S5 is within a predetermined range set by the upper threshold value and the lower threshold value. Extract the region. Then, the feature amount calculation unit 55 calculates a feature amount (here, area) by obtaining the sum of the number of pixels of the region extracted. Then, the pass / fail determination unit 56 determines whether the feature amount (area) extracted by the feature amount calculation unit 55 is within the determination criterion, that is, below a predetermined threshold, according to a predetermined determination criterion. If it is, it is determined that the panel 10 is incompatible, and the panel inspection is terminated. On the other hand, if it is within the criterion, the process proceeds to the next step (step S6).

  Next, when there are image data for which the luminance change amount has not yet been calculated in the N pieces of image data stored in the image storage unit 52, the process returns to step S5 and the same inspection process is repeated. If all of the N pieces of image data stored in the image storage unit 52 are within the criteria, the panel 10 is determined to be suitable and the inspection is terminated (step S7).

  As described above, in the present embodiment, the panel 10 on which the inspection pattern image whose gradation changes at a predetermined time interval is imaged at the predetermined time interval, and the acquired inspection images are compared with each other. By calculating the luminance change amount between inspection images, extracting a region where the luminance change amount is outside a predetermined range, and determining whether the panel 10 is good or bad based on the feature feature amount of the region. It is possible to automatically detect defective cells that are abnormally lit only when displaying a specific gradation or are not lit and display normally when other gradations are displayed, and that are difficult to detect with the conventional technology at high speed and with high accuracy. Become.

  In the present embodiment, a configuration example in which 256 images from the minimum gradation value 0 to the maximum gradation value 255 are displayed on the panel 10 and the inspection image data of 256 images is acquired has been described. These numerical values are merely examples, and are preferably set in consideration of the panel characteristics, the specifications of the plasma display device, the detection accuracy and the inspection time in the inspection device, and the like.

  In addition, each threshold value used in the determination for performing the above-described pass / fail determination may be determined in a timely manner according to the evaluation criteria. Further, when the inspection pattern is switched, the threshold value may be changed for each inspection pattern.

  In the present embodiment, a configuration has been described in which the change amount calculation unit 53 uses the attention inspection image and each of the inspection images captured immediately before and immediately after the generation of the difference image data. A configuration may be adopted in which difference image data is generated using a plurality of inspection images of two or more before and after. In addition, the calculation formula used in the description of the change amount calculation unit 53 in this embodiment is merely an example, and the calculation for calculating the luminance change amount is the attention inspection image and its forward or backward direction. It may be a simple difference operation corresponding to the first-order differential operation with the inspection image of, or a digital filter having three or more tap coefficients is configured, and a temporal change amount is calculated by a weighting operation using the tap coefficients. It may be a calculation as required.

  In the present embodiment, the inspection pattern image displayed on the panel 10 is a pattern in which the display gradation is monotonously increased for each field from the minimum gradation value to the maximum gradation value at the same time for each gradation. However, for example, a pattern that monotonously decreases from the maximum gradation value to the minimum gradation value may be used.

  In the present embodiment, the feature amount calculation unit 55 calculates the area of the region extracted by the region extraction unit 54 as a feature amount, and the pass / fail determination unit 56 compares the size of the area with a predetermined threshold value. Thus, the configuration for determining whether the panel 10 is good or bad has been described. However, as the feature amount, in addition to the area, a width, a length, an average luminance, and the like can be considered. Then, the determination criterion in the pass / fail determination unit 56 may be set according to the calculated feature amount. The pass / fail determination unit 56 determines that the calculated feature amount is outside the determination criterion, and determines that it is incompatible. It can be determined as conforming.

(Embodiment 2)
FIG. 7 is a circuit block diagram of the inspection apparatus 60 according to Embodiment 2 of the present invention. The difference between the second embodiment and the first embodiment is that, in the image processing unit, a maximum / minimum change amount calculation unit having a luminance change amount maximum value detection unit 63 and a minimum value detection unit 64 before the region extraction unit 54. 62 is provided. Other configurations are the same as those in the first embodiment, and the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted.

  As shown in FIG. 7, the image processing unit 61 of the inspection apparatus 60 includes an image storage unit 52, a change amount calculation unit 53, a maximum / minimum change amount calculation unit 62, a region extraction unit 54, and a feature amount calculation unit 55. And a pass / fail judgment unit 56.

  The maximum / minimum change amount calculation unit 62 includes a maximum value detection unit 63 and a minimum value detection unit 64.

  The maximum value detection unit 63 detects and stores the maximum change amount that maximizes the luminance change amount for each pixel. The minimum value detection unit 64 detects and stores the minimum change amount that minimizes the luminance change amount for each pixel.

  The region extraction unit 54 compares the maximum change amount stored in the maximum value detection unit 63 with a preset maximum value threshold value, and extracts a region where the maximum change amount is larger than the maximum value threshold value. Further, the minimum change amount stored in the minimum value detection unit 64 is compared with a predetermined minimum value threshold value, and an area on the inspection image in which the minimum change amount is smaller than the minimum value threshold value is extracted. The region extracting unit 54 may be configured to compare the absolute value of the maximum change amount and the minimum change amount with one threshold value.

  The feature amount calculation unit 55 determines the presence / absence of the region extracted by the region extraction unit 54, and the quality determination unit 56 determines the quality of the panel 10 according to the presence / absence of the region.

  FIG. 8 is a flowchart for explaining the operation of the inspection apparatus 60 according to the second embodiment of the present invention.

  The operation from step S1 to step S5 is the same as the operation from step S1 to step S5 shown in FIG.

  The maximum value detection unit 63 compares the newly calculated brightness change amount with the maximum change amount stored so far, and if the newly calculated brightness change amount is larger, the maximum change stored is stored. The amount is updated to the newly calculated luminance change amount. The minimum value detection unit 64 compares the newly calculated luminance change amount with the minimum change amount stored so far, and if the newly calculated luminance change amount is smaller, the minimum change amount to be stored Is updated to the newly calculated luminance change amount. In this way, the maximum change amount that is the maximum value of the luminance change amount and the minimum change amount that is the minimum value of the luminance change amount are calculated. (Step 10).

  Until the number n of processed image data in step S10 reaches a predetermined number N (in this embodiment, N = 256), the process returns to step S5 to repeat a series of processes. When n = N, the process proceeds to the next step (step S11).

  Next, the region extraction unit 54 extracts a region where the maximum change amount becomes larger than the maximum value threshold value, and extracts a region where the minimum change amount becomes smaller than the minimum value threshold value. The feature amount calculation unit 55 determines whether or not there is an area extracted in this way. The pass / fail judgment unit 56 determines that the panel 10 is incompatible if there is a region where the maximum change amount is larger than the maximum threshold value or there is a region where the minimum change amount is smaller than the minimum value threshold value. If there is no area, it is determined that the panel 10 is suitable, and the panel inspection is finished (step S12).

  As described above, in the present embodiment, the maximum change amount at which the luminance change amount is maximum and the minimum change amount at which the luminance change amount is minimum are detected, and the maximum change amount is larger than the maximum threshold value. Compared to the first embodiment, the non-defective product determination is performed by determining whether the panel 10 is good or bad based on the presence / absence of a large region and the presence / absence of a region where the minimum change amount is smaller than the minimum threshold value. The number of times to perform can be reduced from N times to 2 times, and it is possible to perform pass / fail judgment of the panel 10 in a shorter time.

(Embodiment 3)
FIG. 9 is a circuit block diagram of the inspection apparatus 70 according to the third embodiment of the present invention. The difference between the third embodiment and the second embodiment is that the image storage unit 52 is reduced in the image processing unit. The other configuration is the same as that of the second embodiment, and the same components as those of the second embodiment are denoted by the same reference numerals and detailed description thereof is omitted.

  As shown in FIG. 9, the image processing unit 71 of the inspection apparatus 70 includes a change amount calculation unit 53, a maximum value detection unit 63, a minimum value detection unit 64, a region extraction unit 54, and a feature amount calculation unit 55. And a pass / fail judgment unit 56. Note that it is desirable that the image processing unit 71 is speeded up by, for example, incorporating an FPGA dedicated to image processing into the image processing board in order to realize real-time processing.

  The change amount calculation unit 53 calculates a luminance change amount every time an inspection image is taken from the imaging unit 43. Further, every time the change amount calculation unit 53 calculates the luminance change amount, the maximum value detection unit 63 compares the maximum change amount stored in the maximum value detection unit 63 with the calculated luminance change amount, and The stored data of the maximum value detection unit 63 is updated according to the comparison result. Further, every time the change amount calculation unit 53 calculates the luminance change amount, the minimum value detection unit 64 compares the maximum change amount stored in the minimum value detection unit 64 with the calculated luminance change amount. The stored data of the maximum value detection unit 63 is updated according to the comparison result.

  FIG. 10 is a flowchart for explaining the operation of the inspection apparatus 70 according to the third embodiment of the present invention.

  In addition, since the operation | movement of step S1, step S2, step S10, and step S12 is the same as that of step S1, step S2, step S10, and step S12 shown in FIG. 8 in Embodiment 2, description is abbreviate | omitted.

  In the image processing unit 71, the change amount calculation unit 53 calculates the luminance change amount of each pixel by comparing with the two pieces of image data captured immediately before the current captured image data (step S13).

  The maximum value detection unit 63 updates the maximum change amount and the minimum change amount based on the comparison with the newly calculated luminance change amount (step 10).

  Until the number n of processed image data in step S10 reaches a predetermined number N (in this embodiment, N = 256), the process returns to step S1 to repeat a series of processes. When n = N, the process proceeds to the next step (step S14).

  The pass / fail determination unit 56 determines whether or not the feature amount calculated by the feature amount calculation unit 55 is within the determination criterion. If the feature amount is outside the determination criterion, the panel 10 determines that the panel 10 is incompatible and is within the determination criterion. In that case, it is determined that the panel 10 is suitable, and the panel inspection is terminated (step S12).

  As described above, in the embodiment, the luminance change amount is calculated every time the inspection image is taken, and the maximum change amount and the minimum change amount are updated every time the luminance change amount is calculated. As a result, compared to the second embodiment, the amount of image data that must be stored can be greatly reduced.

  In the third embodiment, it has been described that the area extraction is performed after N sheets of images have been captured and the panel quality is determined. However, each time the imaging unit 43 captures an image, the area extraction is performed and the panel is extracted. It is good also as a structure which performs the quality determination of.

  In the embodiment of the present invention, it is desirable that the imaging timing of the camera 50 is captured in synchronization with the image display timing of the panel 10. In order to realize this operation, for example, a vertical synchronization signal output from the panel drive unit 42 to the panel 10 is input to the imaging control unit 51, and the imaging control unit 51 performs imaging of the camera 50 based on the vertical synchronization signal. Just do it. Alternatively, a configuration may be adopted in which a synchronization signal synchronized with the control of the camera 50 is input from the imaging control unit 51 to the panel drive unit 42 and an inspection image is displayed on the panel 10 based on the synchronization signal. By synchronizing the driving of the panel 10 and the imaging of the camera 50, the display surface of the panel 10 can be stably imaged, so that stable image data with little noise component can be obtained.

  In the embodiment of the present invention, the configuration for inspecting the plasma display panel has been described. However, other image display devices such as a liquid crystal display, an organic EL display, and a surface conduction electron-emitting device display (SED) are also described. It is also possible to adapt the pass / fail test according to the invention.

  INDUSTRIAL APPLICABILITY The present invention is useful as an inspection apparatus and inspection method for a plasma display panel because even a display defect that occurs only when displaying a specific gradation can be automatically detected with high accuracy and high speed. .

The disassembled perspective view which shows the principal part of the panel in Embodiment 1 of this invention. Electrode arrangement of the panel Circuit block diagram of the inspection apparatus according to Embodiment 1 of the present invention The figure which shows an example of the luminance change in the discharge cell with the image data imaged with the inspection apparatus in Embodiment 1 of this invention The figure which shows an example of the luminance variation calculated in the variation calculation part of the inspection apparatus Flow chart for explaining the operation of the inspection apparatus Circuit block diagram of an inspection apparatus according to Embodiment 2 of the present invention Flow chart for explaining the operation of the inspection apparatus Circuit block diagram of an inspection apparatus according to Embodiment 3 of the present invention Flow chart for explaining the operation of the inspection apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Panel 21 Front substrate 22 Scan electrode 23 Sustain electrode 24 Dielectric layer 25 Protective layer 28 Display electrode pair 31 Back substrate 32 Data electrode 33 Insulator layer 34 Partition 35 Phosphor layer 40, 60, 70 Inspection device 41 Panel inspection table 42 Panel drive unit 43 Imaging unit 50 Camera 51 Imaging control unit 44, 61, 71 Image processing unit 52 Image storage unit 53 Change amount calculation unit 54 Area extraction unit 55 Feature amount calculation unit 56 Pass / fail judgment unit 63 Maximum value detection unit 64 Minimum value Detector 62 Maximum and minimum change calculator

Claims (4)

A panel drive unit that displays on the plasma display panel an inspection pattern image whose gradation changes at predetermined time intervals;
An imaging unit that captures an image display surface of the plasma display panel at a time interval according to the predetermined time interval;
A change amount calculation unit that calculates a luminance change amount between the inspection images by comparing a plurality of inspection images captured by the imaging unit;
A region extraction unit that determines whether or not the luminance change amount obtained from the change amount calculation unit is within a predetermined range, and extracts a region outside the predetermined range;
A feature amount calculation unit that calculates a feature amount of the region extracted by the region extraction unit;
An inspection apparatus for a plasma display panel, comprising: a quality determination unit that determines quality of the plasma display panel based on a feature amount obtained from the feature amount calculation unit. A maximum value detecting unit that detects a maximum change amount that is the maximum value of the luminance change amount, and a minimum value detection unit that detects a minimum change amount that is the minimum value of the luminance change amount;
The region extraction unit includes a region where the maximum change detected by the maximum value detection unit is greater than a predetermined maximum value threshold and a minimum change detected by the minimum value detection unit. Extract the region that is smaller than the value threshold,
The apparatus for inspecting a plasma display panel according to claim 1, wherein the feature amount calculation unit is configured to determine the presence or absence of the region extracted by the region extraction unit and output the determination result as a feature amount. . 3. The plasma display panel inspection apparatus according to claim 2, wherein the change amount calculation unit calculates the luminance change amount each time the inspection image is captured. An inspection pattern image whose gradation changes at a predetermined time interval is displayed on the plasma display panel, and an image display surface of the plasma display panel is imaged at a time interval corresponding to the predetermined time interval,
A plurality of the captured inspection images are compared with each other to calculate a luminance change amount between the inspection images;
Determining whether or not the luminance change amount is within a predetermined range, and extracting a region outside the predetermined range;
A method for inspecting a plasma display panel, wherein after the feature quantity of the region is calculated, the quality of the plasma display panel is determined based on the feature quantity.

Images