JP3384713B2 - Plasma display panel inspection method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a plasma display panel, in which R, G, B phosphor pastes having different excitation wavelength-emission characteristics are printed on a back plate, and then dried and fired. By doing so, when the fluorescent screen is formed on the back plate, color unevenness on the fluorescent screen,
Or at it relates to a plasma display panel examination of how to detect the presence or absence of print defects.

[0002]

2. Description of the Related Art As a typical self-luminous electronic display, a cathode ray tube (hereinafter, simply referred to as CR
Examples thereof include T) and plasma display panels (hereinafter simply referred to as PDP), but all of them utilize light emission from the phosphor itself. In the CRT, the phosphor is in a light emitting state by irradiating the phosphor with an electron beam, while in the PDP, the phosphor is in a light emitting state due to ultraviolet radiation from the plasma.
In any case, if the phosphors are not uniformly formed on the phosphor screen in advance, color irregularities may occur on the display screen, or there may be problems such as the presence of pixels that cannot be placed in a light emitting state. ing.

As a fluorescent substance inspection method for a CRT, a fluorescent substance is made to emit light by ultraviolet rays and the light is emitted by using a spectrophotometer as described in, for example, JP-A-8-83569. A method of examining a phosphor by analyzing a spectrum is known.

[0004]

By the way, among the phosphors used in PDPs, there is a normal wavelength band (250 to 35).
The reality is that there is something that cannot be excited by UV light of 0 nm). 17A to 17C show the relationship between the excitation wavelength and the emission intensity of the typical R (red), G (green), and B (blue) phosphors currently used, respectively. .
For example, BaAl ₁₂ O ₁₉ : Mn, which is used as a phosphor for G with little afterglow, cannot be sufficiently excited unless the wavelength is ultraviolet light having a wavelength of 200 nm or less. Therefore, if ultraviolet rays having a wavelength of around 250 nm are used for the phosphor emission inspection, the R and B phosphors are kept in a sufficient light emitting state, but the G phosphor is not placed in a light emitting state. Therefore, the inspection cannot be performed. Therefore,
It is considered that the inspection is performed with ultraviolet rays having a wavelength of 240 nm or less. However, in the inspection in the atmosphere, the energy of the ultraviolet rays is absorbed due to the generation of ozone, so the inspection is usually performed in a vacuum or a nitrogen gas atmosphere. It has become something that needs to be done. However, when the inspection is performed in a vacuum or in an atmosphere of nitrogen gas, it also takes a lot of time for evacuation and filling with nitrogen gas, and the inspection efficiency is drastically reduced as the inspection on the mass production line. It cannot be denied that it is a thing.

Incidentally, as a typical illumination light source that emits ultraviolet rays having a wavelength of 240 nm or less, an excimer lamp or a low pressure mercury lamp can be mentioned. FIG. 18 shows the ultraviolet intensity spectrum emitted from the excimer lamp. From this, it can be seen that the excimer lamp can obtain almost single-wavelength ultraviolet light having a central wavelength of 172 nm. On the other hand, the ultraviolet light emitted from the low-pressure mercury lamp is composed of a plurality of emission line spectra, and the emitted ultraviolet intensity spectrum is shown in FIG. When the low-pressure mercury lamp is used, if the quartz glass is used as the material of the tube, ultraviolet rays having a wavelength of 185 nm are emitted, so that the above-mentioned G phosphor can also be put in a light emitting state. Has become. However, at the same time, ultraviolet rays with a wavelength of 254 nm are also emitted, and the intensity of the emitted ultraviolet rays has a wavelength of 185 n.
It is more than 5 times stronger than that at m. Therefore, the R and B phosphors are in a stronger light emitting state than the G phosphor, and as a result, the deterioration of the inspection accuracy cannot be denied due to the poor white balance. .

[0006] The purpose of the present invention, in the course PDP manufacturing, on the back plate, the excitation wavelength - after the emission characteristics different phases R, G, and B phosphor paste is printed, dried, it is baked When the fluorescent screen is formed on the back plate,
Color unevenness on its phosphor screen, or the presence or absence of printing defects Ru Oh <br/> to provide a PDP inspection method may be detected as an inspection efficiency Univ.

[0007]

The above-mentioned object is to irradiate a phosphor screen, which is placed in an air atmosphere, with an excimer lamp that emits ultraviolet rays having a central wavelength of 172 nm or shorter as a light source. This can be achieved by exhausting ozone generated by the irradiation of ultraviolet rays, capturing an image of the fluorescent screen with an imaging device, and detecting color unevenness or the presence of printing defects from the obtained emission intensity distribution.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. First, prior to a detailed description of the present invention, the inspection object according to the present invention will be briefly described. FIG. 2 shows a PDP (P referred to here) as the inspection object.
The DP is not a product, but refers to a planar appearance configuration of (1) immediately after the phosphor paste is printed on the back plate, and then dried and baked, as will be described later. . As shown in the drawing, the phosphors of three colors for R, G, and B are repeatedly formed in a predetermined order.

FIG. 3 shows a vertical cross section of an example of the PDP 1 as a product. Although PDPs generally have the same light emitting principle, they are roughly classified into an AC type in which electrodes are covered with a dielectric material and a DC type in which electrodes are not covered with a dielectric material. 2 shows an internal structure of an AC type. Explaining the configuration, the PDP 1 is roughly divided into a front plate and a back plate. Of these, the front plate is formed in a state in which an electrode 23 is formed on a front glass substrate 21. In order to prevent the deterioration of the electrode 23 itself due to plasma, the electrode 23 is formed on the front glass substrate 21 in a state of being covered with the dielectric material 30. On the other hand, the back plate is formed on the back glass substrate 22 with the electrodes 23 covered with the dielectric material 30, similarly to the front plate.
On the back plate, a partition wall material is printed and then dried, so that the partition wall 26 is formed by, for example, a sandblast method.
Is formed on the back plate, and then the partition wall 2 is formed.
In the space formed between 6 and the adjacent partition wall 26, R
The fluorescent substance 27 for G, the fluorescent substance 28 for G, and the fluorescent substance 29 for B are formed. Therefore, when a discharge gas is introduced into the space between the partition walls 26, for example, a voltage is applied between the upper and lower electrodes 23 corresponding to the R phosphor 27, and the discharge gas is converted into plasma 24, the plasma 24 is radiated. UV rays 2
As a result of the R red phosphor 27 being excited by 5, the red emission is radiated toward the front glass substrate 21 side. The same applies to each of the G and B phosphors 28 and 29 other than the R phosphor 27.

Now, the present invention will be described in detail. FIG. 4A shows a general PDP manufacturing process. In this case, in order to manufacture the front plate, the electrode forming step 31 and the dielectric film forming step 32 are sequentially performed, and for the rear plate, the electrode forming step 3 is performed.
3, the dielectric film forming step 34, the partition wall forming step 35, and the phosphor forming step 36 are sequentially performed. The front plate and the back plate thus manufactured are then integrally assembled and sealed as a product in the assembly and sealing step 37, and the lighting inspection as a product is performed in the lighting inspection step 38. Has become.

By the way, among the above various steps, the present invention is directly related to the phosphor forming step 36.
(B) shows the phosphor forming step 36 as a more detailed step. As shown in the figure, after the phosphor printing step 39, the drying step 40, and the firing step 41 are sequentially performed, various inspections are performed on the phosphor in the printing state in the print inspection step 42. The inspection result information 43 obtained is fed back to each of the phosphor printing step 39, the drying step 40, and the firing step 41 so that the conditions such as printing, drying, and firing are further improved, and high quality phosphor screen manufacturing is performed. It is supposed to be done. In the printing inspection, the phosphors of three colors may be printed and then simultaneously inspected, or may be inspected after each color is printed. Incidentally, in the phosphor printing step 39, printing of the phosphor is performed by the printing machine, and FIG. 5A shows the configuration of the printing machine. As shown, the squeegee 44 is moved in the direction of the arrow on the surface of the printing screen 45, during which the phosphor paste is transferred to the mesh printing screen 45.
It is extruded in the direction of the back plate from which the phosphor is printed on the back plate. FIG. 5B shows the surface of the squeegee 44 in contact with the printing screen 45, that is, the bottom surface (extrusion surface) of the squeegee 44. The squeegee widths l ₁ and l ₂ at the left and right ends are From the viewpoint of reducing unevenness, it is desirable that they are the same. This is because if the squeegee 44 itself wears, the squeegee width l ₁ ,
This is because if l ₂ becomes different, the amount of phosphor paste extruded from the printing screen 45 becomes different between left and right, and as a result, uneven printing occurs.

FIGS. 6A to 6D also show examples of various printing defects detected in the print inspection step 42. Of these, the one shown in FIG. It can be seen that there is unevenness over the whole area, and a bluish part or a reddish part is partially generated. The cause of such unevenness is mainly due to the difference between the squeegee widths l ₁ and l _{2 described} above. On the other hand, (B) to (D) of the same figure show various printing failure modes as an enlarged state. Among these, in the one shown in (B) of the same figure, the phosphor for B is printed in a state of protruding. However, as a factor of this, there is too much phosphor paste for R only at the time of printing. Further, in the example shown in FIG. 6C, the R phosphor is printed in a state of being displaced from a predetermined position, but the positional displacement between the three-color printing screen and the back plate is considered to be the cause. It has become a thing. Further, in the case shown in FIG.
It can be seen that the fluorescent substance is printed in a state in which the fluorescent substance is partially missing due to lack of the fluorescent substance or in a thin state. Therefore, when various printing defects as described above are detected in the print inspection step 42, the amount and viscosity conditions of the phosphor paste, the drying conditions, the firing conditions (temperature, time, etc.) are reviewed to be optimized. Although it is necessary, the above-mentioned inspection result information 43 is obtained as information regarding the printing state as described above, and based on this, optimization of the viscosity of the phosphor paste and discovery of defects in the printing machine itself, When the optimization adjustment of the process conditions and the like in each of the drying / baking steps is performed, the phosphor can be formed on the back plate in a good condition.

The PDP inspection method in the print inspection step 42 will be described below. FIG. 1 shows the configuration of a first example of the PDP inspection apparatus according to the present invention. PDP to be inspected (PDP here is not a product, but a product immediately after the phosphor paste is printed on the back plate, then dried and baked. The same applies hereinafter.)
As shown in FIG. 1, a shield cover 9 is provided with a fluorescent surface formed of R, G, B phosphors that is excited and emitted by ultraviolet light having a wavelength of at least 240 nm. PDP1 installed inside
For the upper fluorescent screen, the wavelength of 240 nm is emitted from each of the ultraviolet lamps 2 using the lamp lighting device 5 in the atmosphere.
Shorter UV rays are emitted. The fluorescent screen is put into a light emitting state by the irradiation of ultraviolet rays. When the light emitting state at this time is captured by the color television camera 3 and displayed on the monitor television 4, for example,
Printing unevenness and the like can be easily evaluated. As described above, the inspection can be performed with high efficiency by irradiating the fluorescent surface with ultraviolet rays in the atmosphere, but on the other hand, ozone is generated in the shielding cover 9 by the ultraviolet rays irradiation in the atmosphere. ing. This ozone is discharged from the inside of the shielding cover 9 by the ozone discharging device 6 and then returned to oxygen by the ozone reducing device 8 via the duct 7.

FIG. 7 also shows the configuration of the second example in which the light emitting states of the R, G, and B phosphors can be evaluated. As shown, the ultraviolet lamp 2 has a reflector 10
Is mounted, and the color television camera 3 is inspected over the entire fluorescent screen while moving the PDP 1 with the field of view set to be small.

FIG. 8 shows a PDP 1 using a low pressure mercury lamp 11.
On the other hand, it shows the configuration of the third example in which the ultraviolet ray having a wavelength of 185 nm is irradiated. Since the low-pressure mercury lamp 11 also radiates ultraviolet rays having a wavelength of 254 nm at the same time, only the ultraviolet rays of 185 nm are selectively applied to the PDP 1 by using the 254 nm cut filter 12 or the 185 nm transmission filter. Generally, when the emission intensity ratio of the R, G, B phosphors is 2 times or less, or 1/2 times or more, almost white balance is achieved and the inspection accuracy is not deteriorated.
When the wavelength is optimally selected as the ultraviolet ray for irradiating No. 1, each of the R, G, and B phosphors can be placed in a light emitting state of substantially the same intensity. By the way, excimer lamp (center wavelength: 220 nm, 172 nm, 147 nm
It is also possible to set the emission intensity ratio of the R, G, B phosphors to 2 times or less, or 1/2 times or more by irradiating ultraviolet rays from (1) or the like.

FIG. 9 shows the construction of a fourth example in which the R, G, and B phosphors are evaluated for each color. The color separation filter 13 is used to separate the light emission state on the phosphor screen on the PDP 1 into three colors. There are three types of color separation filters 13, one for R phosphor, one for G phosphor, and one for B phosphor. Each time the filter drive device 15 switches them selectively, the emission state at that time is changed. Is captured by the monochrome television camera 14 and displayed on the monitor television 4, so that the printing state of the R, G, B phosphors can be evaluated.

FIG. 10 shows a configuration of a fifth example in which the monitor television 4 shown in FIG. 9 is replaced with an image processing device 16 and a microprocessor 17, and quantitative unevenness evaluation is allowed. . Under the control of the microprocessor 17, the color separation filter 13 is passed through the filter driving device 15.
Each time is sequentially and selectively switched, the light emission state imaged by the monochrome television camera 14 is subjected to image analysis by the image processing device 16 by a known image processing technique.

FIG. 11 also shows the monitor television 4 shown in FIG.
Is a configuration of a sixth example in which the image processing device 16 and the microprocessor 17 are replaced and quantitative unevenness evaluation is possible. Under the control of the microprocessor 17, each time the color separation filter 13 is sequentially and selectively switched via the filter driving device 15, the light emission state imaged by the monochrome television camera 14 is known by the image processing device 16. The image is analyzed by.

FIG. 12 shows two types of low pressure mercury lamps 11 and 1.
8 shows the configuration of the seventh example in which the light emitting state when only the 185 nm ultraviolet ray is irradiated to the fluorescent surface is equivalently obtained by using No. 8 of FIG. In this case, under the control of the microprocessor 17, the low-pressure mercury lamps 11 and 18 are selectively turned on sequentially through the lamp lighting device 5, but when the low-pressure mercury lamp 11 is turned on, , The emission state when the fluorescent surface is irradiated with ultraviolet rays having a wavelength of 185 nm or more is also low-pressure mercury lamp 1.
When 8 is turned on, the light emitting state when the fluorescent surface is irradiated with ultraviolet rays having a wavelength of 254 nm or more is obtained, and therefore, on the image processing device 16, as a difference between the light emitting states, The light emission state on the fluorescent screen when only the ultraviolet ray having a wavelength of 185 nm is irradiated is equivalently obtained by the difference image calculation, and then image processing is performed. However, as shown in FIG. 13, it is also possible to use a long-ultraviolet transmission filter 19 that transmits only ultraviolet rays of 254 nm or more, instead of the low-pressure mercury lamp 18. On the image processing device 16, a wavelength of 18 is obtained as a difference between the light emission state when the long ultraviolet transmission filter 19 is present and the light emission state when the long ultraviolet transmission filter 19 is not present, using the drive device 20.
The light-emission state on the phosphor screen when only 5 nm ultraviolet rays are irradiated is equivalently obtained, and the image is processed.

14 (A) and 14 (B) are equivalent to each other in the state of light emission on the fluorescent screen when only the ultraviolet ray having a wavelength of 185 nm is irradiated by the configuration shown in FIG. 12 or 13. The principle of what is obtained is shown as a spectral characteristic. As shown in FIG. 7A, the emission characteristics 51 when the fluorescent surface is irradiated with ultraviolet rays of 185 nm or more
As shown in FIG. 6B, the difference between the emission characteristics 52 when the ultraviolet ray of 254 nm or more is irradiated on the fluorescent surface is as shown in FIG. It can be seen that the light emission characteristics at the time of lighting are indirectly obtained. It should be noted that B, G, and R in FIG. 14B indicate transmission bands of filters for color separation.

Similarly, FIG. 15 shows an example of a PDP inspection processing sequence on the configuration shown in FIG. 12 or FIG. Since this is already clear from the above description, no further description is necessary.

FIGS. 16 (A) to 16 (C) schematically show the R, G, B corresponding emission intensity difference images obtained by the inspection process shown in FIG. In these figures, the shaded portion is shown as a portion having a high emission intensity, but from this, for example, a portion having a large amount of phosphor paste printed and applied is known.

Various kinds of PDP inspection devices according to the present invention have been described above. In any case, as shown in FIG. 4B, the inspection result information 43 has more improved conditions such as printing, drying and baking. If necessary, phosphor printing step 39, drying step 4
0, when feedback is given to each of the firing steps 41,
High quality phosphor screen can be manufactured.

[0024]

As described above , the present invention provides a PDP.
During the manufacture of, the phosphor plate for R, G, B having different excitation wavelength-emission characteristics is printed on the back plate, and then dried and baked to form a phosphor screen on the back plate. In doing so, the unevenness of color on the fluorescent screen or the presence or absence of a printing defect can be detected as a high inspection efficiency.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a first example of a plasma display panel inspection apparatus according to the present invention.

FIG. 2 is a diagram showing a planar appearance configuration of a plasma display panel as an inspection object according to the present invention.

FIG. 3 is a view showing a vertical cross section of an example of the plasma display panel.

4A and 4B are views showing a general plasma display panel manufacturing process and a phosphor forming process in the manufacturing process as more detailed processes, respectively.

5A and 5B are views for explaining a method for printing a phosphor on a back plate by a printing machine.

6A to 6D are views showing examples of various printing defects detected in a print inspection process.

FIG. 7 is a diagram showing the configuration of a second example of the plasma display panel inspection device according to the present invention, in which the emission states of the individual R, G, and B phosphors can be evaluated.

FIG. 8 is a diagram showing the configuration of a third example of the plasma display panel inspection apparatus according to the present invention, which is adapted to be irradiated with ultraviolet rays having a wavelength of 185 nm.

FIG. 9 is a diagram showing a configuration of a fourth example of the plasma display panel inspection apparatus according to the present invention, in which the R, G, and B phosphors can be evaluated for each color.

FIG. 10 is a diagram showing a configuration of a plasma display panel inspection apparatus according to a fifth example of the present invention, which allows quantitative unevenness evaluation by an image processing apparatus and a microprocessor.

FIG. 11 is a sixth view of a plasma display panel inspection apparatus according to the present invention, which is also capable of quantitative unevenness evaluation by an image processing apparatus and a microprocessor.
Figure showing the configuration of the example

FIG. 12 is a diagram showing the configuration of a seventh example of the plasma display panel inspection apparatus according to the present invention when two types of low-pressure mercury lamps are used.

FIG. 13 is a diagram showing a configuration of an eighth example of the plasma display panel inspection apparatus according to the present invention when the same two types of low-pressure mercury lamps are used.

14 (A) and 14 (B) show an equivalent light emission state on the fluorescent screen when only ultraviolet rays having a wavelength of 185 nm are irradiated by the configuration shown in FIG. 12 or FIG. Diagram showing the principle of what is obtained as spectral characteristics

15 is a diagram showing an example of a PDP inspection processing sequence on the configuration shown in FIG. 12 or FIG.

16A to 16C are diagrams schematically showing R, G, B corresponding emission intensity difference images obtained by the inspection process shown in FIG.

17 (A) to (C) are diagrams showing the relationship between the excitation wavelength and the emission intensity of typical R, G, and B phosphors currently used, respectively.

FIG. 18 is a diagram showing an ultraviolet intensity spectrum emitted from an excimer lamp.

FIG. 19 is a diagram showing an ultraviolet intensity spectrum emitted from a low-pressure mercury lamp in the same manner.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Plasma display panel (PDP), 2 ... Ultraviolet lamp, 3 ... Color television camera, 4 ... Monitor television, 6 ... Ozone discharge device, 11, 18 ... Low-pressure mercury lamp, 12 ... 254 nm cut filter, 13 ... Color separation filter , 16 ... Image processing device, 17 ... Microprocessor, 21 ... Front glass substrate, 22 ... Rear glass substrate, 3
9 ... Phosphor printing step, 40 ... Drying step, 41 ... Firing step, 42 ... Printing inspection step, 43 ... Inspection result information

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mikio Hongo 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Hitachi, Ltd. Production Technology Research Laboratory (72) Inventor Masaru Furukawa 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Home Appliance Information Media Business Division, Hitachi, Ltd. (56) Reference JP-A-8-83569 (JP, A) JP-A-63-315935 (JP, A) JP-A-9-273913 (JP, A) Special Kaihei 9-17341 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01J 9/42 H01J 9/227 G01M 11/00

Claims (3)

(57) [Claims] 1. A plasma display panel inspection method for detecting the presence or absence of color unevenness on a fluorescent screen formed on a back plate of a plasma display panel, or the presence or absence of a printing defect, which is placed in an air atmosphere. The excimer lamp that emits ultraviolet rays having a central wavelength of 172 nm or shorter is used as a light source to irradiate the fluorescent surface, and the ozone generated by the ultraviolet irradiation is exhausted, and the fluorescent surface is imaged by an imaging device. A method for inspecting a plasma display panel, which comprises detecting color unevenness or the presence of a printing defect from the obtained emission intensity distribution. 2. A plasma display panel, wherein R, which has different excitation wavelength-emission characteristics, is formed on the back plate during manufacturing.
A plasma display panel for detecting the presence or absence of color unevenness or a printing defect on the fluorescent surface formed on the back plate by printing and drying the G and B phosphor paste. An inspection method, in which ozone generated by irradiation of ultraviolet rays is excluded, and ultraviolet rays having a wavelength of 185 nm or more from one low-pressure mercury lamp are
The emission state when irradiated to the fluorescent surface in the atmosphere and the wavelength from the other low-pressure mercury lamp are 254
As a difference from the light emitting state when the phosphor screen is irradiated with ultraviolet rays of nm or more, the emission intensity or the emission intensity distribution on the phosphor screen when the ultraviolet ray having a wavelength of 185 nm is irradiated. on obtained from the luminous intensity or luminous intensity distribution, uneven color or a plasma display panel inspection method as the presence or absence of printing defects are detected. 3. A plasma display panel is manufactured, on which R, which has different excitation wavelength-emission characteristics, is formed on the back plate.
A plasma display panel for detecting the presence or absence of color unevenness or a printing defect on the fluorescent surface formed on the back plate by printing and drying the G and B phosphor paste. An inspection method, in which ozone generated by irradiation of ultraviolet rays is excluded, and ultraviolet rays having a wavelength of 185 nm or more from a low-pressure mercury lamp are emitted to the fluorescent surface in the air atmosphere. As a difference between the state and the light emitting state when the ultraviolet ray having a wavelength of 185 nm or more from the low-pressure mercury lamp is applied to the fluorescent surface through an optical filter that transmits the ultraviolet ray having a wavelength of 254 nm or more, the wavelength is 185 nm. on ultraviolet to obtain a light emission intensity or the emission intensity distribution on the phosphor screen at when illuminated, from the emission intensity or emission intensity distribution, uneven color or print missing, The plasma display panel inspection method as presence or absence is detected.