JP3897802B2 - Method for evaluating the application state of an object - Google Patents

Description

  The present invention relates to an object application state evaluation method, and more particularly to a method for evaluating a phosphor application state of a plasma display panel (PDP).

  Conventionally, in a matrix display type PDP that displays characters and figures by a combination of dots (pixels) arranged vertically and horizontally, a surface discharge type PDP suitable for displaying a color other than the emission color of the discharge gas by a phosphor is provided. Are known.

  FIG. 2 is an exploded perspective view showing an example of a cross-sectional structure of a portion corresponding to one pixel EG of the PDP. The PDP illustrated in FIG. 2 is an AC drive type PDP having a three-electrode structure, and includes a glass substrate 11 on the display surface side, a pair of display electrodes X and Y extending in parallel with each other in the horizontal direction, and AC drive. Dielectric layer 17 and its protective film 18, glass substrate 21 on the back side, address electrode 22 orthogonal to display electrodes X and Y, rib (partition) 29 parallel to address electrode 22, and fluorescence for color display It consists of a body layer 28 and the like.

  A discharge gas for exciting the phosphor layer 28 with ultraviolet rays is sealed in the internal discharge space 30. Such a discharge space 30 is partitioned for each unit light emitting region EU in the extending direction of the display electrodes X and Y by the ribs 29, and the gap size is defined. The rib 29 is made of a low-melting glass layer having a thickness (height) h of about 100 to 130 μm.

  In the PDP, selection for selecting display or non-display at the intersection of one display electrode Y and the address electrode 22 in each of the three unit light emission regions EU associated with one pixel EG as shown in the figure. A discharge cell is defined, and a main discharge cell (picture discharge cell) is defined between the display electrodes in the vicinity of the selected discharge cell.

  The phosphor layer 28 is provided between the ribs 29 on the glass substrate 21 on the side opposite to the display electrodes X and Y in order to avoid ion bombardment due to the surface discharge, and is excited by ultraviolet rays generated by the surface discharge of the main discharge cell. Is emitted. The light emitted from the surface of the phosphor layer 28 (the surface in contact with the discharge space) passes through the dielectric layer 17 and the glass substrate 11 and is emitted from the display surface.

  In the PDP, the emission colors of the phosphor layers 28 corresponding to the three unit emission regions EU are sequentially red (R), green (G), and blue (B) (the alphabet R in the figure). , G, and B indicate emission colors). Further, since the display electrodes X and Y are arranged on the display surface H side with respect to the phosphor layer 28, the transparent conductive film 41 made of a nesa film or the like and its conductive product are used in order to increase the display brightness. It is comprised from the metal film 42 for supplementing.

  In the PDP 1 having the above-described structure, predetermined constituent elements are separately provided for the glass substrates 11 and 21, the glass substrates 11 and 21 are arranged to face each other, the periphery of the gap is sealed, and internal exhaust and discharge are performed. Manufactured by a series of steps of filling with gas.

  At that time, in the production on the glass substrate 21 side, the screen printing method is usually used for forming the phosphor layer 28. The phosphor layer 28 is formed by printing the phosphor paste in order for each color in a predetermined pattern using a screen mask (also referred to as a screen type) and then firing the phosphor paste.

  In order to increase the display brightness, it is desirable that the phosphor layer 28 has as large a surface area as possible. That is, the ideal shape of the phosphor layer 28 is such that the side surface of the rib 29 is thinly covered with the surface of the glass substrate 21 (including the surface of the address electrode 22) between the ribs 29 as shown in FIG. It is.

  Therefore, the phosphor layer 28 needs to be formed after the rib 29 is provided. Usually, the address electrode 22 is formed on the glass substrate 21 before the rib 29 is provided.

  However, since the ribs 29 have a height of about 140 μm, the phosphor paste is printed in a form in which the phosphor paste is dropped from a screen mask that is raised about 140 μm from the surface of the glass substrate 21, so that the phosphor layer 28 is formed. Variations in area and thickness may result in non-uniform display brightness and color tone, which may impair display quality, and discharge characteristics may become unstable due to variations in the covering state of the address electrodes 22.

  However, display defects caused by such variations in the application state of phosphors are found only at the display test stage after completion of the PDP. Therefore, in order to investigate the cause during the manufacturing process, a method of visually evaluating the application state of the phosphor using a microscope has been adopted. It takes time to reduce the production efficiency of PDP. The present invention has been made in consideration of such circumstances, and provides a method capable of efficiently evaluating the application state of the phosphor immediately after the formation of the phosphor layer during the manufacturing process of the PDP. It is.

The present invention is a method for evaluating the application state of a phosphor applied between a plurality of ribs provided on a substrate surface, and after at least two kinds of phosphors having different emission colors are applied between corresponding ribs and the substrate surface wherein the substrate surface while illuminated with ultraviolet light is scanned in a different light detectors for detecting the light emission color of each phosphor, compared with each other pulse width of the electrical pulse signals obtained from the detector The present invention provides an object application state evaluation method characterized by evaluating the application state of each phosphor.

As a specific example of the substrate in the present invention, a substrate for PDP having a plurality of parallel ribs on the surface can be mentioned. An example of the phosphor is a paste-like phosphor applied to form a phosphor layer between ribs provided on a PDP substrate.
That is, the present invention can be applied to, for example, a PDP substrate in which the substrate has a plurality of parallel ribs on the surface and the phosphor is applied between the ribs.

According to the first invention, the profiles of the first object surface before and after application of the second object are compared, and the cross-sectional shape of the applied second object can be inspected nondestructively. It becomes possible to easily and efficiently evaluate the application state of the second object.
According to the second invention, it is possible to easily evaluate the overlap and bias of the phosphors applied to the substrate immediately after the formation of the phosphor layer.

As an embodiment of the present invention, a method for evaluating the phosphor coating state of PDP will be described in detail below.
First, a process of forming a plurality of parallel ribs on the surface of the substrate and applying a phosphor between the ribs will be described with reference to FIGS.
On the glass substrate 21, for example, an address electrode 22 made of silver and having a thickness of about 20 μm, and a rib 29 made of low-melting glass and having a height h of about 130 μm are provided by a printing method.

  At this time, a screen mask (not shown) in which strip-shaped openings having a width of, for example, 60 μm are arranged at a constant pitch p (for example, 220 μm) is used for printing the silver paste and the glass paste corresponding to the address electrodes 22 and the ribs 29. . In this case, the width of the address electrode 22 is 60 to 70 μm, and the widths w1 and w2 of the bottom portion and the top vicinity portion of the rib 29 are about 80 μm and 40 μm, respectively.

  Next, the process proceeds to the formation process of the phosphor layer 28, and the phosphor paste 28a is printed for each emission color by the following procedure. That is, as shown in FIG. 1A, a screen mask 60 in which openings 61 having a predetermined width are provided at a pitch three times the pitch p is appropriately aligned with the glass substrate 21 and the rib 29 Arrange so that they abut.

  Then, a phosphor paste 28 a obtained by mixing a phosphor of a predetermined emission color (for example, R) and a vehicle is dropped between the ribs 29 through the openings 61. At this time, as the phosphor paste 28a, one having a phosphor content of 10 to 50% by weight is used in order to make the phosphor layer 28 have a thickness of 50 μm or less as described above. The vehicle is composed of a cellulose or acrylic thickener resin and an alcohol or ester organic solvent.

  In addition, here, the phosphor paste 28 a is pushed out from the opening 61 toward the glass substrate 21 so as to substantially fill the gaps between the ribs 29. For this purpose, the corner squeegee 71 is moved in the direction of the arrow M1.

  Subsequently, for the other emission colors (G and B), the phosphor paste 28a having a phosphor content of 10 to 50% by weight is sequentially printed so as to substantially fill the gaps between the ribs 29 [ FIG. 1 (b)].

Thereafter, the phosphor paste 28a is dried and fired at a temperature of 500 to 600 ° C. [FIG. 1 (c)].
For example, (Y, Gd) BO ₃ : Eu ³⁺ is used as the phosphor having the emission color R, and Zn ₂ SiO ₄ : Mn is used as the phosphor having the emission color G, and the emission color is B. For example, BaMgAl ₁₄ O ₂₃ : Eu ²⁺ can be used as the phosphor.

  Next, in the first invention, the displacement meter, for example, modulates the laser diode light at a high frequency and radiates it toward the object, and compares the phase of the reflected modulated wave with the reference wave to the distance from the object. A known optical displacement meter for measuring can be used.

  The data processing means for comparing and evaluating the measurement data includes, for example, a CPU, ROM, RAM, and I / O port.

  A CRT, a printer, or the like can be used as a means for outputting the processing result. Note that the data processing means and the output means can be integrally configured by a personal computer.

  The ultraviolet light source according to the second invention includes, for example, a combination of a laser diode or a single-color light emitting diode that emits laser light having a wavelength in the ultraviolet region and a lens that converges the light on the substrate. Can be used.

  As the photodetector, if the phosphors to be applied are three colors of R, G, and B, for example, a photodiode or fort transistor that can individually detect light of R, G, and B colors is used, and fluorescence is used. If all the bodies have the same color (single color), a photodiode or a phototransistor that can detect the light of that color can be used.

  Since the electrical signal obtained from the photodetector has a pulse-like waveform representing the coating width of the phosphor, it is possible to determine the overlap and positional deviation of adjacent phosphors from the interval of the waveform.

Example (1)
4 and 5 are a side view and a front view of the evaluation apparatus used in Example (1). In these drawings, a mounting table 51 for mounting the substrate 21 is mounted on a Y-axis sliding device 52 that moves in the direction of the arrow YY ′ by a motor 52a, and the Y-axis sliding device 52 is arrowed by a motor 53a. It is mounted on an X-axis sliding device 53 that moves in the XX ′ direction. Further, the displacement meter 54 is fixed via a support arm 56 to a Z-axis sliding device 55 that moves in the direction of the arrow ZZ ′ by a motor 55a.

  FIG. 6 is a block diagram of a control device used in the embodiment (1). A microcomputer 61 incorporating a CPU, ROM, RAM, and I / O port includes a keyboard 62 and a displacement meter for setting various measurement conditions. Data is processed in response to the output from 54, and the motors 52a, 53a, 55a are driven, and images and numerical values are output to the CRT 63.

  A method for evaluating the phosphor application state using this apparatus will be described with reference to the flowchart of FIG. The operator fixes the substrate 21 before applying the phosphor to a predetermined position of the mounting table 51 so that the rib is parallel to the arrow YY ′ direction (step S1), and the keyboard 62 measures the measurement position and the measurement length. Is set (step S2), and then an activation command is input from the keyboard 62 (step S3).

  Accordingly, the distance of the displacement meter 54 from the substrate 21 is adjusted, and the displacement meter 54 moves to the set measurement position (step S4). Then, the displacement meter 54 scans the substrate by moving at a constant speed across the rib in the direction of the arrow X or X 'by a set length.

  At this time, the output signal of the displacement meter 54 is stored in the RAM of the microcomputer 61 (step S5). Steps S4 and S5 are executed for all positions set in step S2 (step S6).

  Next, the operator carries the substrate 21 out of the mounting table 51 (step S7), executes a phosphor coating and baking process (step S9), and then fixes the substrate 21 to a predetermined position on the mounting table 51 again. (Step S10). Then, when the steps S4 to S7 are executed, each measurement data is processed by the microcomputer 61 and displayed on the CRT 64.

FIG. 8 shows an example of the display.
FIG. 8A shows a profile obtained from the measurement data for a predetermined portion of the substrate 21 before the phosphor coating. A high mountain represents the cross-sectional shape of the rib 29 and a low mountain represents the cross-sectional shape of the electrode 22. ing.

FIG. 8B is a profile obtained from measurement data for the same part of the substrate 21 after phosphor coating.
(C) in FIG. 8 is a superposition of the profiles (A) and (B). Thereby, since the cross section of the phosphor layer is obtained as a hatched portion in FIG. 8C, the thickness of the phosphor, the application region, the application accuracy, and the like can be evaluated from the shape.

Example (2)
9 and 10 are a side view and a front view of the evaluation apparatus used in Example (2). In these drawings, a mounting table 151 for mounting the substrate 21 is mounted on a Y-axis sliding device 152 that moves in the direction of arrow YY ′ by a motor 152a. It is mounted on an X-axis sliding device 153 that moves in the XX ′ direction. The photodetector 154 and the light source 157 are fixed via a support arm 56 to a Z-axis sliding device 55 that moves in the direction of arrow ZZ ′ by a motor 155a.

  The light source 157 includes a laser diode that emits an ultraviolet light beam and a lens that converges the light beam on the substrate. The photodetector 154 includes an R photodiode 154r, a G photodiode 154g, and a B photodiode 154b (see FIG. 11). The excitation light from the phosphor is detected respectively.

  FIG. 11 is a block diagram of a control device used in the embodiment (2). A microcomputer 161 incorporating a CPU, ROM, RAM, and I / O port includes a keyboard 162 for setting various measurement conditions and light detection. In response to the output from the device 154, data processing is performed to drive the motors 152a, 153a, and 155a, and to output images and numerical values to the CRT 163.

  A method for evaluating the phosphor application state using this apparatus will be described with reference to the flowchart of FIG. The operator fixes the substrate 21 before applying the phosphor to a predetermined position of the mounting table 151 so that the rib 29 is parallel to the arrow YY ′ direction (step S21), and the keyboard 162 measures the measurement position and the measurement length. Is set (step S22), and an activation command is input from the keyboard 162 (step S23).

  Thereby, the distance from the substrate 21 of the photodetector 154 is adjusted, and the photodetector 154 moves to the set measurement position (step S24). Then, the photodetector 154 scans the substrate by moving at a constant speed across the rib in the direction of the arrow X or X ′ by a set length.

  At this time, the output signal of the photodetector 154 is stored in the RAM of the microcomputer 161 (step S25). Steps S4 and S5 are executed for all positions set in step S22 (step S26). Each measurement data is displayed on the CRT 164 based on a command from the keyboard 162.

  13 and 14 show display examples. In these figures, Sr, Sg, and Sb indicate temporal changes in the outputs of the R photodiode 154r, the G photodiode 154g, and the B photodiode 154b, respectively.

  When the waveform of FIG. 13 is obtained, since the pulses are regularly arranged, it is evaluated that the phosphor layers for R, G, B are applied with a normal width and a normal pitch between the ribs. Is done. When the waveform of FIG. 14 is obtained, the pulse of (b) overlaps the pulse of (b) and the width of the pulse of (c) is shortened, so that the phosphor for G overlaps the phosphor for R. It is evaluated that the width of the phosphor for B is narrower than the normal width.

It is process drawing which shows the manufacturing method of PDP which concerns on this invention. It is a disassembled perspective view which shows an example of the cross-section of the part corresponding to one pixel of PDP which concerns on this invention. It is principal part sectional drawing which shows the ideal shape of the fluorescent substance layer which concerns on this invention. It is a side view of the evaluation apparatus of Example (1). It is a front view of the evaluation apparatus of Example (1). It is a block diagram of the control apparatus of Example (1). It is a flowchart which shows operation | movement of Example (1). It is explanatory drawing which shows the example of a display of Example (1). It is a side view of the evaluation apparatus of Example (2). It is a front view of the evaluation apparatus of Example (2). It is a block diagram of the control apparatus of Example (2). It is a flowchart which shows operation | movement of Example (2). It is a wave form diagram which shows the example of a display of Example (2). It is a wave form diagram which shows the example of a display of Example (2).

Explanation of symbols

21 Glass substrate (substrate)
22 address electrode 29 rib 28 phosphor layer 28a phosphor paste 71 square squeegee

Claims (2)

A method for evaluating the application state of a phosphor applied between a plurality of ribs provided on a substrate surface ,
The substrate surface after at least two kinds of phosphors having different emission colors are applied between the corresponding ribs is illuminated with ultraviolet rays, and the substrate surface is scanned with different photodetectors that detect the emission colors of the respective phosphors. and, coating state evaluation method of an object and evaluating the coating state of each of phosphor pulse width compared to each other of the electrical pulse signals obtained from the detector.   2. The object application state evaluation method according to claim 1, wherein the substrate has a plurality of ribs on the surface, and the phosphor is applied between the ribs.

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