JP4457786B2 - Plasma display panel inspection method and inspection apparatus - Google Patents

Description

  The present invention relates to an inspection method and an inspection apparatus for inspecting a phosphor layer in a barrier rib pattern formed on a back substrate of a plasma display panel.

  Generally, a plasma display panel (hereinafter referred to as a PDP) has a structure in which two glass substrates, a front substrate and a rear substrate, are bonded together. Display electrodes, dielectric layers, protective layers, and the like are formed on the front substrate, and address electrodes, barrier ribs, phosphor layers, and the like are formed on the rear substrate. A discharge space is formed by arranging these glass substrates to face each other, and a gas mainly composed of a rare gas such as Ne or Xe is sealed in the discharge space.

  FIG. 14 is a cross-sectional view showing an example of an AC (alternating current) type color PDP, and FIGS. 14A and 14B show cross sections in directions orthogonal to each other. The rear substrate 501 has a stripe-shaped address electrode 502, a dielectric layer 503 covering the address electrode 502, a partition wall 504 for partitioning these discharges, and a red, green, and blue phosphor that covers the dielectric layer 503 and the partition wall 504. A layer 505 is formed. The front substrate 506 is provided with a display electrode (a set of two) composed of a transparent electrode 507 and a bus electrode 508 so as to be orthogonal to the address electrode 502, and further covers the display electrode to cover the dielectric layer 509 and MgO (magnesium oxide). A protective layer 510 is formed. A discharge cell, which is a minimum unit for performing display, includes a region surrounded by two display electrodes, one address electrode 502, and a partition 504. An arbitrary voltage image is displayed with light transmitted through the front substrate 506 by exciting and emitting the phosphor of the phosphor layer 505 by vacuum ultraviolet rays generated by discharge by applying an AC voltage between the two display electrodes in the discharge cell. Is what you do.

  Among the manufacturing methods of PDPs, electrode materials such as display electrodes and address electrodes 502 are formed on a glass substrate by vacuum deposition, sputtering, plating, screen printing, coating, film laminating, etc. There are a method of forming a film and patterning it by a photolithography method and a method of patterning by a screen printing method or offset printing. Further, as a method for forming the partition 504, there are a sand blast method, a method of patterning by a photolithography method after forming a photosensitive paste film, and the like. As a method for forming the phosphor layer 505, there are a coating method using a dispenser, a method of selectively filling phosphor pastes of each color between the partition walls 504 by a screen printing method, etc. Usually, after applying the paste, a drying process and a firing process are performed. After completion.

  The phosphor layer 505 contracts and changes its shape through the drying process. Due to this shape, the vacuum ultraviolet-excited light emission capability of each discharge cell is different, and image defects such as color unevenness occur. An example of the cross-sectional shape when the phosphor layer shape is ideal is shown in FIG. As shown in FIG. 12, in the case where the surface of the phosphor layer 505 is formed in a smooth and continuous curve in the region delimited by the barrier ribs 504, vacuum ultraviolet rays generated by discharge are efficiently generated by the phosphor layer. 505 is irradiated. On the other hand, FIG. 13 shows an example of a cross-sectional shape when the phosphor layer shape is defective. As shown in FIG. 13, in the case where the surface of the phosphor layer 505 has an acute angle and has a singular point 505a and is formed by a plurality of non-continuous curves, there is a portion shaded by the irradiation of vacuum ultraviolet rays generated by discharge. As a result, sufficient excitation light emission cannot be obtained.

  Conventionally, as a method for inspecting the shape of such a phosphor layer, a human has been visually inspected by irradiating the substrate after drying the phosphor paste with vacuum ultraviolet rays. As a method other than visual inspection, the phosphor layer is irradiated with light having a wavelength that does not excite the phosphor before drying the phosphor paste, and the reflected light pattern is analyzed to detect defects in the phosphor layer. An inspection method for detection is disclosed (for example, Patent Document 1).

Further, an inspection method for detecting defects in the phosphor layer by irradiating the phosphor layer with ultraviolet light and detecting excitation radiation from the phosphor layer with a line sensor is also disclosed (for example, Patent Document 2).
JP 2004-39571 A JP 2004-45353 A

  However, these conventional inspection methods have the following problems. The shape abnormality of the phosphor layer often occurs due to shrinkage or the like when the phosphor paste is dried. Therefore, in the method of inspecting the phosphor paste before drying, it is not possible to determine the shape abnormality that has occurred after the phosphor paste is dried, so that the substrate that has become defective in the drying process flows out to the subsequent process. Challenges arise.

  On the other hand, in the inspection method in which the light generated from the phosphor layer excited by irradiating the phosphor layer with ultraviolet light is detected by the line sensor, the Xe resonance line having a wavelength of 147 nm generated by the original PDP discharge is used as the light source. Is impossible due to the absorption wavelength characteristics of the lamp material, and therefore a 222 nm Xe excimer lamp that is normally used is used. However, since the excimer lamp cannot excite the phosphor layer sufficiently, there is a problem that the exposure time needs to be long and the processing time becomes long in order to sufficiently detect the emitted light with the line sensor.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a PDP inspection method and inspection apparatus that can detect a defective shape of a phosphor layer in a short time and reliably and can determine whether it is good or bad. .

In order to solve the above-described problems, a PDP inspection method of the present invention is a PDP inspection method for inspecting the shape of a phosphor formed in a region partitioned by a partition on a substrate, and applying a phosphor paste. The step of irradiating the phosphor surface with ultraviolet light after drying, the step of imaging the light emitted from the phosphor excited by the ultraviolet ray with an area sensor camera, and the phosphor formation state by analyzing the light emission pattern from the phosphor look including the steps of measuring, the step of irradiating ultraviolet rays, the substrate surface to form a phosphor is irradiated with ultraviolet rays from at least two directions non-simultaneously.

  According to such an inspection method, it is possible to detect a defective shape of the phosphor in a short time and reliably and to determine whether it is good or bad.

A PDP inspection method of the present invention is a PDP inspection method for inspecting the shape of a phosphor formed in a region partitioned by a partition on a substrate, and is applied to a phosphor surface after a phosphor paste is applied and dried. When irradiating ultraviolet rays, the substrate surface on which the phosphor is formed is irradiated with ultraviolet rays by continuously changing the irradiation angle, and the light emitted from the phosphor excited by the ultraviolet rays is continuously captured by the area sensor camera. And a step of analyzing a light emission pattern from the phosphor and measuring a formation state of the phosphor. According to such a method, it is possible to obtain more detailed phosphor information such as the schematic shape of the phosphor.

The PDP inspection apparatus of the present invention is a PDP inspection apparatus for inspecting the shape of a phosphor applied to a region partitioned by a partition on a substrate, and is disposed above the substrate and continuously irradiates the substrate with an irradiation angle. to varied and ultraviolet light source for irradiating ultraviolet light to the phosphor, a continuous angle setting means for continuously changing the irradiation angle of the ultraviolet rays from the ultraviolet light source to the substrate, the fluorescence excited by ultraviolet rays is disposed above the substrate the light emission from the body continuously with the area sensor camera for capturing, image processing means for computing an image data obtained by the area sensor camera, and a quality determination means for determining the acceptability of the state of formation of a phosphor ing.

According to such a configuration, it is possible to detect a defective shape of the phosphor in a short time and to determine whether it is good or bad. In addition, more detailed phosphor information such as the schematic shape of the phosphor can be obtained.

  According to the PDP inspection method and the inspection apparatus according to the present invention, it is possible to detect a defective shape of a phosphor in a short time and reliably and to determine whether it is good or bad.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing an outline of a PDP inspection apparatus according to the first embodiment of the present invention. FIG. 2 is a flowchart of the PDP inspection method.

  As shown in FIG. 1, the PDP inspection apparatus has a holding mechanism 102 that places and moves a back substrate 101 that has been coated with a phosphor paste, which is a phosphor material, and moves, and a sensitivity characteristic in the wavelength range of visible light as a light receiving element. An area sensor camera 103 having approximately 10 million CCDs (Charge Coupled Devices) in a matrix, a lens barrel 104 having an objective lens capable of setting the substrate resolution per pixel of CCD to 5 μm square, and coating on the rear substrate 101 Thereafter, an ultraviolet light source 105 that irradiates ultraviolet parallel light having a wavelength of 222 nm for exciting and emitting the dried phosphor layer, a mechanism unit 109 serving as an angle setting unit that sets the ultraviolet light source 105 to an arbitrary angle, and an area sensor camera 103 Image processing means 106 for processing the image obtained by the above, pass / fail judgment means 107, image And a board data storage device 108. In addition, since it is necessary to detect only the ultraviolet-excited light emission from the phosphor layer with the area sensor camera 103, the PDP inspection apparatus is installed in a dark room and can block outside light.

  Hereinafter, the operation of the first exemplary embodiment of the present invention will be described. This will be described with reference to the flowchart of FIG. The back substrate 101 is carried into the holding mechanism 102 of the PDP inspection apparatus, and the phosphor layer is moved to a predetermined position and fixedly held so that the phosphor layer coated and dried on the area partitioned by the partition wall is on the upper surface. Next, the ultraviolet light source 105 disposed above the back substrate 101 is irradiated with ultraviolet rays at a predetermined angle, and excitation light emitted from the phosphor layer at that time is emitted from the area sensor camera 103 disposed above the back substrate 101. Take an image with.

  FIG. 3 is a view showing an example of irradiating the phosphor layer 201 formed between the barrier ribs 200 with ultraviolet rays. The shape of the phosphor layer 201 is formed with a smooth and continuous curve as shown in FIG. It shows the case of an ideal shape. An address electrode 112 and a dielectric layer 111 covering the address electrode 112 are formed on the rear substrate 101, and a partition wall 200 and a phosphor layer 201 are formed on the dielectric layer 111. The phosphor layer 201 is composed of a phosphor paste. Is applied and dried. As shown in FIG. 3, first, the irradiation angle is 45 degrees, that is, the rear substrate 101 is irradiated with parallel ultraviolet rays from an angle of 45 degrees, and the emitted light is imaged by the area sensor camera 103. At this time, the image is taken with the exposure time of the camera being 500 ms and the lens aperture being open. At this time, the excitation light emission state differs depending on the shape of the phosphor layer 201 in the barrier rib 200, and the phosphor layer 201 in the shaded portion of the ultraviolet rays is not directly excited but only weakly excited by the reflected ultraviolet rays. .

  In this way, when the amount of excitation luminescence accumulated in the area sensor camera 103 installed above the back substrate 101 is a light amount distribution in which the distance between the partition walls of each discharge cell is abscissa and the amount of light is ordinate, In the case of the phosphor layer shape shown in FIG. 3, the light quantity distribution has a gentle curve as shown in FIG.

  However, FIG. 5 shows a case where the surface of the phosphor layer 201 has a plurality of discontinuous surfaces such as the recess 203. In the case where the phosphor layer 201 has such a portion that is shaded by ultraviolet rays, the amount of light in this portion is reduced, so the light amount distribution is as shown in FIG. The phosphor formed between the barrier ribs 200 by comparing the light amount distribution of FIG. 4 when the shape of the phosphor layer 201 is normal and the light amount distribution of FIG. 6 where the shape of the phosphor layer 201 is abnormal. A defect in the left portion of the layer 201 can be determined.

  Next, as the second imaging, as shown in FIG. 7, the irradiation angle of ultraviolet rays is set to 135 degrees, that is, an angle of 135 degrees with respect to the back substrate 101, and irradiation with parallel light ultraviolet rays is performed for an exposure time of 500 ms. The image is taken with the lens aperture open. FIG. 7 shows a case where the surface of the phosphor layer 201 has a plurality of non-continuous surfaces such as dents 203. Further, the light amount distribution in this case is shown in FIG. 8, and the light amount is reduced in the recess 203. Also in this case, a light amount distribution corresponding to the shape of the phosphor layer can be obtained, and a defect in the right portion of the phosphor layer 201 can be determined.

  According to such a method, a portion of the phosphor layer that is directly irradiated with ultraviolet rays is strongly excited to generate a strong light amount. Also, shadowed portions such as dents are weakly excited by reflection and generate a weak amount of light. Therefore, the difference in the amount of light between the directly excited portion and the portion excited by reflection in the shadow is large, and the shape of the phosphor layer in the discharge cell can be obtained by irradiating ultraviolet parallel light at different angles. it can.

  Next, the image obtained by the area sensor camera 103 is processed by an image processing means 106 comprising a computer. As the image processing method here, the imaging data is processed by a known method such as noise removal processing. Further, the image obtained by the pass / fail judgment means 107 is checked against an adjacent comparison method or a preset reference value to determine whether or not the shape of the phosphor layer is within an allowable range. That is, according to the above process, the quality of the phosphor layer can be reliably determined in a short time. Note that the noise removal process is a smoothing process for removing noise in the video signal, and a maximum value filter, a minimum value filter, a median filter, or the like can be used as the technique.

  In the first embodiment, the substrate surface on which the phosphor layer is formed is irradiated with ultraviolet rays from two directions of 45 degrees and 135 degrees with respect to the substrate. On the other hand, irradiation may be performed from one direction such as a vertical direction, but the inspection accuracy is slightly lowered. On the contrary, the inspection accuracy can be further improved by increasing the irradiation angle in more than two directions.

(Second Embodiment)
FIG. 9 is a diagram showing an outline of a PDP inspection apparatus according to the second embodiment of the present invention. FIG. 10 is a flowchart of the PDP inspection method.

  As shown in FIG. 9, the basic configuration and operation of the PDP inspection apparatus and inspection method in the second embodiment of the present invention are the same as those in the first embodiment, and are characteristic in the present embodiment. One of them is that a continuous angle setting unit 110 capable of arbitrarily and continuously changing the irradiation angle of the ultraviolet light from the ultraviolet light source 105 is provided.

Therefore, the flowchart shown in FIG. 10 differs from the flowchart of the first embodiment shown in FIG. 2 in that the irradiation angle is changed in two steps, the first time and the second time, in the first embodiment. However, in the present embodiment, the irradiation angle is continuously changed by the continuous angle setting means 110.

Figure 11 shows the same phosphor layers 201 and FIG. 5 explained in the first embodiment, in the case of continuously changing the irradiation angle of the ultraviolet flat row light, the light amount distribution. As shown in FIG. 11, according to the second embodiment of the present invention, it is possible to obtain a light amount distribution over the entire width between the partition walls 200 and to perform inspection in a short time.

  In addition, according to the second embodiment of the present invention, since the continuous shape information of the phosphor layer 201 can be obtained by continuously changing the irradiation angle and irradiating the ultraviolet rays, the irradiation angle is changed. More detailed information than the limited first embodiment can be obtained, and a more reliable pass / fail judgment can be made.

  Note that the light receiving element of the area sensor camera 103 may be not only a CCD but also a CMOS sensor, and its effective pixels are not limited to 10 million pixels, and the higher the number of pixels, the higher the resolution and the single imaging. Needless to say, the area that can be measured by the method increases.

  Further, the wavelength of ultraviolet light used for exciting and emitting the phosphor layer is 222 nm, but it is possible to use vacuum ultraviolet light having a shorter wavelength, for example, wavelength 172 nm, but vacuum ultraviolet light is oxygen in the air. Therefore, it is necessary to take measures such as maintaining the inside of the PDP inspection apparatus at a low pressure or purging the inside of the apparatus with nitrogen or the like.

  Further, in the embodiment of the present invention, the substrate resolution per pixel is 5 μm square, but changing according to the size of the target discharge cell is not contrary to the spirit of the present invention.

  Furthermore, in the embodiment of the present invention, the excitation light emission from the phosphor layer is received by an area sensor camera equipped with a CCD, the distance between partition walls in each discharge cell is taken on the horizontal axis, and the light quantity distribution is taken on the vertical axis. Although the quality is judged based on the cross-sectional shape, the light quantity of the entire discharge cell may be compared in units of CCD pixels.

  It is also possible to determine the quality based on the amount of change in the light quantity by differentiating the light quantity.

  The PDP inspection method and inspection apparatus according to the present invention image and analyze light emitted from a phosphor excited by ultraviolet rays, thereby detecting a defective shape of the phosphor layer in a short time and determining whether it is good or bad. Therefore, it is useful for the inspection of PDP.

The figure which shows the outline of the PDP inspection apparatus in the 1st Embodiment of this invention The flowchart of the PDP inspection method in the first embodiment of the present invention Sectional drawing when irradiating ultraviolet rays at an angle of 45 degrees when the shape of the phosphor layer is ideal in the first embodiment of the present invention In the first embodiment of the present invention, when the shape of the phosphor layer is ideal, the light amount distribution diagram when ultraviolet rays are irradiated at an angle of 45 degrees Sectional drawing when irradiating ultraviolet rays at an angle of 45 degrees when the shape of the phosphor layer is discontinuous in the first embodiment of the present invention In the first embodiment of the present invention, when the shape of the phosphor layer is discontinuous, a light amount distribution diagram when ultraviolet rays are irradiated at an angle of 45 degrees Sectional drawing when irradiating ultraviolet rays at an angle of 135 degrees when the shape of the phosphor layer in the first embodiment of the present invention is discontinuous In the first embodiment of the present invention, when the shape of the phosphor layer is discontinuous, a light amount distribution diagram when ultraviolet rays are irradiated at an angle of 135 degrees The figure which shows the outline of the PDP inspection apparatus in the 2nd Embodiment of this invention The flowchart of the PDP inspection method in the 2nd Embodiment of this invention In the second embodiment of the present invention, when the shape of the phosphor layer is discontinuous, the light amount distribution diagram when the ultraviolet ray is continuously irradiated Sectional drawing which shows an example when a phosphor layer shape is ideal Sectional drawing which shows an example when there exists a defect in a fluorescent substance layer shape Sectional drawing which shows an example of the structure of PDP

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Back substrate 102 Holding mechanism 103 Area sensor camera 104 Lens tube 105 Ultraviolet light source 106 Image processing means 107 Pass / fail judgment means 108 Image and board data storage device 109 Mechanism part 110 Continuous angle setting means 112 Address electrode 200, 504 Partition 201, 505 Fluorescence Body layer 203 dent

Claims (3)

A plasma display panel inspection method for inspecting the shape of a phosphor formed in a region partitioned by barrier ribs on a substrate, the step of irradiating the phosphor surface after applying and drying the phosphor paste with ultraviolet rays , seen containing a step of imaging the light emitted from the phosphor excited by the ultraviolet area sensor camera, and measuring the formation state of the phosphor analyzes emission pattern from the phosphor, the ultraviolet In the plasma display panel inspection method , wherein the step of irradiating the surface of the substrate on which the phosphor is formed irradiates the ultraviolet rays in at least two directions at the same time . A plasma display panel inspection method for inspecting the shape of a phosphor formed in a region partitioned by a partition on a substrate, and when irradiating ultraviolet light on a phosphor surface after applying and drying the phosphor paste, Irradiating the substrate surface on which the phosphor is formed with ultraviolet rays by continuously changing an irradiation angle; and continuously imaging an emission from the phosphor excited by the ultraviolet rays with an area sensor camera; Analyzing the light emission pattern from the phosphor and measuring the formation state of the phosphor . A plasma display panel inspection apparatus for inspecting a shape of a phosphor applied to a region partitioned by a partition on a substrate, wherein the apparatus is disposed above the substrate and continuously changes an irradiation angle with respect to the substrate. An ultraviolet light source for irradiating the phosphor with ultraviolet light, continuous angle setting means for continuously changing an irradiation angle of the ultraviolet light from the ultraviolet light source to the substrate, and the pump disposed above the substrate and excited by the ultraviolet light. an area sensor camera for capturing continuously emitting light from the phosphor, and an image processing means for computing an image data obtained by the area sensor camera, quality determination means for determining the acceptability of the state of formation of the phosphor And a plasma display panel inspection apparatus.

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