JP4432011B2 - Apparatus and method for inspecting plasma display panel back plate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an inspection apparatus and inspection method for a plasma display panel back plate, and more particularly, to an apparatus and method capable of more accurately inspecting RGB phosphors formed on a plasma display panel back plate.
[0002]
[Prior art]
Usually, phosphors for R (red), G (green), and B (blue) are repeatedly applied in order in the form of stripes on the back plate of the plasma display panel. If there is a defect, the light emission state of a predetermined phosphor cannot be obtained, and the image on the display panel is defective. Therefore, the phosphor coating state is inspected at the manufacturing stage of the plasma display panel back plate.
[0003]
Since the plasma display panel is a display device that irradiates the phosphor formed on the back plate with ultraviolet rays and performs display by light emission from the phosphor, the back plate is irradiated with ultraviolet rays as an inspection method. Thus, the method of inspecting the enlarged image by causing the phosphor to emit light is the most accurate inspection method.
[0004]
However, since visual inspection is inefficient, for example, a technique described in Japanese Patent Application Laid-Open No. 11-16498 has been studied. Japanese Patent Application Laid-Open No. 11-16498 discloses an automatic inspection method in which an inspection by ultraviolet irradiation is performed while eliminating ozone, and a predetermined inspection is possible even in the atmosphere.
[0005]
[Problems to be solved by the invention]
However, the method disclosed in Japanese Patent Application Laid-Open No. 11-16498 has the following problems.
Since there is no review imaging device having ultraviolet irradiation means and only automatic inspection is performed, the defect overdetection rate and the oversight rate are high. Further, in the case of only automatic inspection, it is difficult to identify the defect type and the cause of occurrence because the defect image cannot be visually confirmed.
[0006]
An object of the present invention is to solve the above-mentioned problems in the prior art, reduce overdetection and oversight, and accurately inspect the cause of occurrence of a defect. Is to provide.
[0007]
[Means for Solving the Problems]
In order to solve the above-described problems, a plasma display panel back plate inspection apparatus according to the present invention is an RGB phosphor inspection device formed on a plasma display panel back plate, and includes a review imaging device including ultraviolet irradiation means. And a visual field range of the review imaging means and a visual field range of the automatic inspection imaging means overlap each other . Since the review imaging means irradiates the defect with ultraviolet rays, causes the phosphor to emit light, and visually determines the quality, because the user can check the status of the defect in a state close to using the product , Over-detection, inspection with little oversight becomes possible. In particular, it is possible to prevent overdetection by visual inspection even when the detection threshold for automatic inspection is strictly set to prevent oversight. Accordingly, it is possible to reduce product loss due to over-detection and user complaints due to oversight, and to reduce manufacturing costs.
[0008]
In the plasma display panel back plate inspection apparatus according to the present invention, the ultraviolet irradiation means of the review imaging means can also serve as the illumination means of the automatic inspection imaging means.
[0009]
Further, for example, a two-dimensional CCD camera can be used as the light receiving unit of the review imaging unit, and a one-dimensional CCD camera can be used as the light receiving unit of the automatic inspection imaging unit.
[0010]
In the present invention, the visual field range of the imaging means for review overlaps the visual field range of the imaging means for automatic inspection . Moreover, it is preferable that the review imaging unit has a focal length of 50 mm or more and is arranged so as not to obstruct the visual field of the automatic inspection imaging unit. The review imaging unit may further include a visible light illumination unit.
[0011]
The imaging means for automatic inspection has a θ-axis adjustment mechanism that is an angle adjustment mechanism around an axis perpendicular to the back plate of the plasma display panel, and a φ-axis adjustment mechanism that is an angle adjustment mechanism with respect to the vertical axis. Is preferred.
[0012]
The plasma display panel back plate inspection method according to the present invention uses the inspection apparatus as described above to determine whether the defects detected by the automatic inspection imaging means are good or bad by visual inspection using the review imaging means. It consists of the method characterized by.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
1 and 2 show a plasma display panel back plate inspection apparatus according to an embodiment of the present invention. In the figure, reference numeral 1 denotes a back plate of a plasma display panel (hereinafter also abbreviated as PDP) to be used for inspection. The PDP back plate 1 has an R plate as shown in FIG. Phosphors 305, 306, and 307 for (red), G (green), and B (blue) are repeatedly applied in order in a stripe shape.
[0014]
As shown in FIG. 4, the plasma display panel back plate mechanism 300 includes RGB phosphors 305, 306, 307 between the partition walls 304 on the dielectric layer 303 on which the address electrodes 302 are arranged on the back glass substrate 301. Are sequentially applied in a stripe pattern, a front glass substrate 308 is provided above the back plate 1, and a display electrode 309 is provided between the back plate 1 and the front glass substrate 308. The disposed dielectric layer 310 and protective film 311 are interposed. Plasma 312 is generated by the voltage between the display electrode 309 and the address electrode 302, whereby the phosphor at the selected position is colored, and a desired color display is performed by the combination of the coloring of each phosphor. ing.
[0015]
The RGB phosphors 305, 306, and 307 are applied to the PDP back plate 1 by screen printing, for example, as shown in FIG. 5, and the excess amount of the phosphor applied through the printing screen 402 is scraped off with the squeegee 401. As a result, as shown in FIG. 4, each phosphor 305, 306, 307 is applied between the partition walls 304 by a predetermined amount.
[0016]
However, if the RGB phosphors 305, 306, and 307 are not applied as prescribed, color unevenness as shown in FIG. 6 may occur, for example, reddish color unevenness 501 or bluish color unevenness. 502 etc. arise. Further, as shown in FIG. 7, in the arrangement of RGB phosphors 305, 306, and 307, a portion 601 in which a phosphor of a certain color protrudes from a phosphor portion of the next color and color mixing occurs, or omission of coating occurs. As a result, a dark spot 602 may occur.
[0017]
Various defects as described above in the application of the RGB phosphors 305, 306, and 307 to the PDP back plate 1 are inspected by the inspection apparatus shown in FIG. As will be described with reference to FIG. 1 again, the PDP back plate 1 is transported by the transport device 2 including transport rollers and the transport device 2 is controlled by the drive control device 4.
[0018]
Above the transport device 2, an XY gantry stage 3, an ultraviolet irradiation device 5, an automatic inspection imaging device 7, and a review imaging device 8 as shown in FIG. The ultraviolet irradiation device 5, the automatic inspection imaging device 7, and the review imaging device 8 are fixed to one housing, and this housing is referred to as a measurement head 9. The measuring head 9 including the automatic inspection imaging device 7, the review imaging device 8, and the ultraviolet irradiation device 5 is attached to the XY gantry stage 3 as shown in FIG. The XY gantry stage 3 is for scanning the measuring head 9 over the entire surface of the PDP back plate 1. The operations of the XY gantry stage 3 and the transport device 2 are controlled by a drive control device 4.
[0019]
The automatic inspection imaging device 7 is connected to the image processing device 10, and the review imaging device 8 is also connected to the image processing device 10. The control device 11 is connected to the drive control device 4, the lighting control device 6 that controls the lighting of the ultraviolet irradiation device, and the image processing device 10, and controls the operation of these devices. A display device 12 is connected to the image processing device 10, and the display device 12 can display defect information detected by the image processing device 10.
[0020]
The ultraviolet irradiation device 5 is for exciting and emitting the phosphor coated on the PDP back plate 1 and irradiates the PDP back plate 1 with ultraviolet rays. As an ultraviolet ray source, an excimer lamp, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultraviolet laser, or the like can be selected. However, an excimer lamp having a wavelength of 222 nm is preferable because it generates less ozone and the RGB phosphor emits light in a balanced manner. . In addition, it is preferable to transmit ultraviolet rays using an optical fiber such as quartz glass because the configuration of the measurement head can be simplified, the attenuation in the air is small, and the amount of ozone generated is small. Further, when the inspection is performed by irradiating the phosphor with ultraviolet rays as the automatic inspection, for example, as shown in FIG. 8, the single ultraviolet irradiation device 5 (ultraviolet irradiation means) and the imaging device 7 for automatic inspection and the review are used. It is preferable to irradiate the field of view of the imaging device 8 with ultraviolet rays because the configuration is simplified and the cost is reduced. In the form shown in FIG. 8, the review imaging device 8 has a visible light illumination device 21.
[0021]
The automatic inspection imaging device 7 divides a certain range on the PDP back plate 1 into pixels, measures the luminance of each pixel, converts it into an image signal, and transmits the image signal to the image processing device 10. A one-dimensional or two-dimensional CCD or an imaging tube can be selected as the light receiving unit of the automatic inspection imaging device 7, but when a one-dimensional CCD camera is used, inspection can be performed at high speed. Furthermore, if a TDI camera is used, even if the illumination is weak, inspection can be performed with high sensitivity. When ultraviolet rays are used as illumination for the automatic inspection imaging device 7, it is preferable to use a color line sensor camera because each image of RGB phosphors can be obtained by one camera and the optical system can be simplified. Note that the type of illumination of the imaging device for automatic inspection 7 is not limited to ultraviolet rays. If illumination is performed from an oblique direction using visible light, phosphor coating defects with surface irregularities can be detected. .
[0022]
The imaging device for review 8 is for visually judging the quality of defects detected by the automatic inspection. The imaging device for review 8 converts a certain range of luminance on the PDP back plate 1 that emits light into a video signal by the ultraviolet rays irradiated from the ultraviolet irradiation device 5. The converted video signal is temporarily stored in the memory by the image processing device 10 and then transmitted to the display device 12. The quality is visually judged from the image displayed on the display device 12. Therefore, according to the present invention, the defect is irradiated with ultraviolet rays, the phosphor is made to emit light, and the quality is visually judged. Therefore, it is possible to confirm the state of the defect in a state close to the state where the user uses the product. Thus, high-precision inspection becomes possible.
[0023]
It is preferable to use a two-dimensional CCD camera as the light receiving portion because an image can be obtained without scanning the measuring head 9 during review. Further, when a two-dimensional color CCD camera is used, it is sufficient to identify which color phosphor has a defect. Furthermore, it is preferable to have an automatic gain adjustment function (AGC function).
[0024]
As the optical system part, an optical system having a focal length of 50 mm or more is preferable because it can be arranged so as not to obstruct the visual field of the automatic inspection imaging device 7. The optical magnification is preferably 0.5 to 5 times. Furthermore, it is more preferable to use a zoom lens because defects of any size can be determined.
[0025]
In order to perform a review from the result of the automatic inspection, it is necessary to obtain an accurate positional relationship between the review imaging device 8 and the automatic inspection imaging device 7. However, in machine accuracy, errors may occur in millimeters due to fitting of screw holes, etc., so a certain reference point is captured by both imaging devices, and the positional relationship is determined from the coordinates on the image, the coordinates of the XY gantry stage 3, etc. Have to ask for, and work time is long.
[0026]
Therefore, as shown in FIG. 8 , the same reference point is imaged by both imaging devices by arranging the review imaging device 8 so that the visual field range of the review imaging device 8 overlaps the visual field range of the automatic inspection imaging device 7. Thus, an accurate positional relationship can be obtained in units of pixel resolution of the imaging apparatus, and the work is completed in a short time. In addition, when the review imaging device 8 has the visible light illumination means 21, a reference point other than the phosphor can be used, and the operator is not exposed to ultraviolet rays. Therefore, it is more preferable because the operation can be performed easily and safely. Further, when the automatic inspection imaging device 7 is a one-dimensional camera, as shown in FIG. 9, an adjustment mechanism for an angle with respect to an axis perpendicular to the back plate of the plasma display panel (in the example shown, an angle with respect to the mounting surface 22). When a certain φ-axis adjusting device 23 is provided, the visual field range of the review imaging device 8 and the visual field range of the automatic inspection imaging device 7 can be overlapped by simple adjustment.
[0027]
The image processing apparatus 10 is for detecting defects that occur in the phosphor. The image processing apparatus 10 inputs image signals of each of the RGB phosphors imaged by the automatic inspection imaging device 7 and performs image analysis using a known image processing technique. And detect defects.
[0028]
In addition, when performing difference processing between pixels that are separated from each other as image processing, it is necessary to match the stripe direction of the phosphor with either the X or Y coordinate of the image processing device in order to suppress the occurrence of pseudo defects. is there. Therefore, as shown in FIG. 10, when the θ-axis adjusting device 24 that is an angle adjusting mechanism (an angle adjusting mechanism with respect to the mounting surface 22 in the illustrated example) around the axis perpendicular to the back plate of the plasma display panel is provided, The body stripe direction can be easily adjusted.
[0029]
The control device 11 gives an operation command to the transport device 2, the ultraviolet irradiation device 5, the imaging devices 7 and 8, and the image processing device 10 based on the determined procedure, and the image processing device 6 is operated by the display device 12. Each defect information detected in is displayed.
[0030]
In the present invention, the RGB arrangement on the rear panel of the plasma display panel is not limited to the parallel stripe shape as shown in FIG. For example, as shown in FIG. 11, an AC plasma display panel back plate 104 in which RGB are arranged in a matrix may be used.
[0031]
FIG. 12 is a block diagram showing another embodiment of the present invention.
The visual inspection is performed only when a defect occurs and the inspection time is long. Therefore, if it is directly installed in the production line, the visual inspection becomes a rule and the production efficiency decreases. Therefore, as shown in FIG. 12, even when a defect occurs by separating visual inspection from automatic inspection via a buffer, production can be continued without reducing efficiency. Further, the embodiment of the automatic inspection is not limited to that shown in the above-described embodiment. For example, as shown in FIG. 13, the imaging device 32 is arranged in a line with respect to the PDP back plate 31, and the imaging device 32 and the ultraviolet irradiation device 33. On the other hand, when the PDP substrate 31 is transported by the transport device 34, the entire surface can be inspected. As described above, the relative position, the arrangement relationship, and the arrangement of the imaging devices between the imaging device, the ultraviolet irradiation device, and the PDP back plate can be set substantially arbitrarily.
[0032]
The operation of the inspection apparatus according to the present invention will be described with respect to the above-described embodiment. When the PDP back plate 1 is input from the upstream apparatus to the transfer apparatus 2, the transfer apparatus 2 gives a substrate input signal to the control apparatus 11, The conveyance of the PDP back plate 1 is started. When the PDP back plate 1 is transported to a predetermined location, the transport device 2 fixes the PDP back plate 1 by a back plate fixing device (not shown) and gives a fixing completion signal to the control device 11. When the fixing completion signal is input, the control device 11 turns on the ultraviolet irradiation device 5 via the lighting control device 6. When the XY gantry stage 3 transports the measuring head 9 to a predetermined imaging start position, it gives a capture preparation completion signal to the control device 11. When the capture preparation completion signal is input, the control device 11 gives an image capture start signal to the XY gantry stage 3 and the image processing device 10. The XY gantry stage 3 given the image capture start signal starts to move at a predetermined speed, stops after moving a predetermined distance. The image processing apparatus 10 given the image capturing start signal starts capturing the image signal output from the automatic inspection imaging device 7. The image processing apparatus 10 stores an image signal and detects a defect occurring in the PDP back plate 1 by a known image processing technique. Hereinafter, the control device 11 moves the XY gantry stage 3 so that the measuring head 9 can inspect the entire PDP back plate 1. After the inspection of the entire surface is completed, the control device 11 notifies the inspector of the completion of the automatic inspection with a lamp or the like.
[0033]
The inspector who is ready for the visual inspection gives a review start signal to the control device 11. The control device 11 given the review start signal moves the measurement head for all defect candidates detected by the automatic inspection based on the defect information and turns on the ultraviolet irradiation device 5, and then sends it to the review imaging device 8. Then, an image of the defective part is taken and displayed on the display device 12. The inspector visually inspects the defect candidate portion displayed on the display device 12 to determine whether it is acceptable. The inspector visually inspects all defect candidate portions and then gives a visual inspection end signal to the control device 11. The control device 11 given the visual inspection end signal gives a PDP back plate discharge signal to the transport device 2. The conveyance device 2 to which the discharge signal is given carries the PDP back plate 1 to the downstream device.
[0034]
【Example】
Hereinafter, the present invention will be specifically described with reference to examples. However, the present invention is not limited to this.
Example 1
As the ultraviolet irradiation device 5, an excimer lamp enclosing Kr and Cr having a lighting frequency of 14.56 MHz and an irradiation ultraviolet central wavelength of 222 nm was used. The review imaging device 7 uses a Sony two-dimensional color CCD camera (XC-711RR) as the light receiving portion, and the optical system portion is a 0.75-4.5 × zoom lens (ML-Z07545DM) manufactured by Moritex. It was used. Further, a halogen light source (MHF-D100LR) manufactured by Moritex Corporation was used as a visible light illumination device. The imaging device 8 for automatic inspection used a 2048-pixel three-plate type color line sensor camera (3CL2048B) manufactured by NED, and selected a lens so that one pixel corresponds to 30 μm on the PDP back plate. The PDP back plate 1 used a substrate including printing defects and color unevenness, and the XY gantry stage 3 transported the measurement head at 0.5 m / min to perform automatic inspection. After the automatic inspection, the detected defect candidate portion was visually inspected using the review imaging device 7. As a result, it was possible to accurately detect printing defects and color unevenness of the phosphors of RGB.
[0035]
【The invention's effect】
As described above, according to the plasma display panel back plate inspection apparatus and method according to the present invention, the following various effects can be obtained.
(1) The defect is irradiated with ultraviolet rays, the phosphor is made to emit light, and the quality is visually judged. Therefore, the user can check the state of the defect in a state close to the state in which the product is used. Inspection with little oversight is possible. Therefore, it is possible to reduce product loss due to over-detection and user complaints due to oversight, thereby reducing manufacturing costs.
(2) Since it is not necessary to separately prepare ultraviolet irradiation means, the inspection cost can be kept low.
(3) It can be automatically inspected at high speed and can be easily reviewed without moving the stage.
(4) The positional relationship between the review imaging means and the automatic inspection imaging means can be obtained accurately and in a short time.
(5) Since the visual field of the imaging means for automatic inspection is not obstructed, the inspection width can be increased and the inspection time can be shortened.
(6) When the positional relationship between the review imaging means and the automatic inspection imaging means is obtained, it is not necessary to use ultraviolet rays, so that it is possible to easily perform the work without the need for protective equipment.
(7) It is possible to easily adjust the formation direction of the phosphor layer and the direction of the line sensor camera element, and the positional relationship between the visual field of the review imaging unit and the visual field of the automatic inspection imaging unit.
(8) Since the defect candidate points are detected by automatic inspection and the quality is visually judged, the inspection can be performed at high speed and with high accuracy.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a plasma display panel back plate inspection apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view around an XY gantry stage unit of the apparatus of FIG.
FIG. 3 is a schematic plan view of a plasma display panel back plate.
FIG. 4 is a partial longitudinal sectional view of a plasma display panel.
FIG. 5 is a perspective view for explaining a printing method of a phosphor on a back plate by a printing machine.
FIG. 6 is a diagram illustrating examples of various printing defects detected in a print inspection process.
FIG. 7 is a diagram illustrating another example of various print defects detected in the print inspection process.
FIG. 8 is a schematic configuration diagram showing the arrangement relationship among an automatic inspection imaging device, a review imaging device, and an ultraviolet irradiation device.
FIG. 9 is a schematic side view showing a φ-axis adjusting mechanism.
FIG. 10 is a schematic plan view showing a θ-axis adjusting mechanism.
FIG. 11 is a schematic plan view showing another example of a plasma display panel back plate.
FIG. 12 is a block diagram showing another embodiment of the present invention.
FIG. 13 is a schematic perspective view showing another embodiment of the automatic inspection according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 31, 104 Plasma display panel backplates 2, 34 Conveyance device 3 XY gantry stage 4 Drive control device 5, 33 Ultraviolet irradiation device 6 Lighting control device 7 Imaging device for automatic inspection 8 Imaging device for review 9 Measuring head 10 Image processing Device 11 Control device 12 Display device 21 Visible light illumination device 22 Mounting surface 23 φ-axis adjusting device 24 θ-axis adjusting device 33 Imaging device 300 Plasma display panel back plate mechanism 301 Rear glass substrate 302 Address electrode 303 Dielectric layer 304 Partition wall 305 Fluorescence Body (R color)
306 Phosphor (G color)
307 Phosphor (B color)
308 Front glass substrate 309 Display electrode 310 Dielectric layer 311 Protective film 312 Plasma 401 Squeegee 402 Print screen 501 Uneven color (reddish part)
502 Color unevenness (blue part)
601 Mixed color portion 602 Dark spot

Claims (4)

An inspection apparatus for RGB phosphors formed on a back plate of a plasma display panel , comprising review imaging means provided with ultraviolet irradiation means and automatic inspection imaging means, and a visual field range of the review imaging means An inspection apparatus for a back plate of a plasma display panel , wherein the visual field ranges of the imaging means for automatic inspection overlap . The apparatus for inspecting a rear panel of a plasma display panel according to claim 1 , wherein the review imaging unit further includes a visible light illumination unit. The imaging device for automatic inspection includes a θ-axis adjusting mechanism that is an angle adjusting mechanism around an axis perpendicular to the back plate of the plasma display panel, and a φ-axis adjusting mechanism that is an angle adjusting mechanism with respect to the vertical axis. The apparatus for inspecting a back panel of a plasma display panel according to claim 1 or 2 , wherein Using the inspection apparatus according to any one of claims 1 to 3 and a defect detected by the automatic inspection imaging means, using the review imaging means, and judging the quality visually, Inspection method for plasma display panel back plate.

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