JPH10283932A - Inspecting method for shadow mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately inspect, by one time, the shapes of the through hole and recesses of a shadow mask, by measuring the shapes of the through hole and recesses based on light passed through the through hole, and light reflected from a shadow mask; and judging whether the shapes of the through hole and recesses are formed as desired shapes or not. SOLUTION: A through hole, small hole recesses, and a large hole are formed at given intervals on a shadow mask 1. Radiated light 12a, from a first light radiating means 8a, reaches one side surface side of the shadow mask, and radiated light 12a, irradiated to the through hole portion, passes through the through hole, becoming transmitted light 13; and the transmitted light 13 is picked up by a measuring means 9 provided on another side surface side of the shadow mask 1. Successively, radiated light 12b from a second light radiating means 8b reaches another side surface side of the shadow mask 1 too to be reflected, and this reflected light 14 is picked up by the measuring means 9 to be judged by a judging means 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of inspecting a shadow mask having a plurality of through holes formed in a thin metal plate, and more particularly to a high definition shadow mask having a large number of through holes and a small diameter of the through holes. The method for inspecting.

[0002]

2. Description of the Related Art A shadow mask used for a color picture tube or the like has a plurality of through holes formed in a thin metal plate, and is mainly manufactured by a photo-etching method. In addition, there is an increasing demand for higher definition of the shadow mask, and as shown in the example of the manufacturing process shown in FIG. 5 below, a through hole formed in the shadow mask is formed into a small hole recess formed on one surface, and a through hole formed on the other surface. It is becoming the mainstream to form it by using a large hole recess formed on the surface.

[0003] That is, after the surface of a metal sheet (shadow mask material 6) serving as a shadow mask is degreased, leveled, and cleaned, a photoresist solution is applied to both surfaces and dried.
A photoresist film 2 is formed. Next, the shadow mask material 6 is exposed through an exposure mask having a predetermined pattern.
Is exposed with a negative pattern of a small hole image on one side and a negative pattern of a large hole image on the other side. Thereafter, if a development process for dissolving the unexposed and uncured photoresist film with warm water is performed, as shown in FIG. 5A, the small-hole resist film 2a exposing the shadow mask material 6 from the opening is formed. Large resist film
2b is obtained on both sides.

After that, a hardening process and a burning process are performed on the resist film 2, and a first stage etching is performed from both front and back surfaces. At the time of etching, the shadow mask material 6 exposed from the resist film 2 is isotropically etched to form a concave portion. In the first etching step of this example, as shown in FIG. 5B, the etching progress is stopped halfway.

Next, the shadow mask material 6 is washed with water, washed and dried, and then, for example, a photocurable resin is applied by a gravure coating method or the like, and the resin is irradiated with light to obtain a light-cured resin as shown in FIG.
As shown in (c), an etching prevention layer 4 that completely fills the small hole recesses formed by the preceding etching is formed. The surface on which the etching prevention layer 4 is formed may be on the small hole side or on the large hole side, but is often formed on the small hole side.

Subsequently, as shown in FIG. 5D, a second etching step of etching the shadow mask material 6 only from the large hole side is performed, and the large hole concave portion 3b is enlarged, so that the small hole from the large hole side is reduced. A through hole 5 penetrating the hole recess 3a is formed. Finally, a stripping step of stripping and removing the etching prevention layer 4 and the resist film 2 is performed to obtain FIG. 5E, and then unnecessary portions are cut to obtain the shadow mask 1.

In FIG. 5 described above, an example of a manufacturing method of coating and forming the etching prevention layer 4 is described. However, a film-like film is attached as the etching prevention layer 4 or the etching prevention layer 4 is not used. There is also a method of manufacturing a shadow mask. There is also a method of forming the through-hole 5 by etching from one side.

As described in the above-described example, when the shadow mask is manufactured, the through-hole 5 is constituted by at least the concave portion 3 formed on one surface of the shadow mask 1. Is formed with a large number of small-diameter through-holes 5 penetrating a thin metal plate.

When the shadow mask 1 is installed in a color picture tube or the like, each through-hole 5 formed in the shadow mask 1 is formed.
Has a function to correctly guide an electron beam emitted from an electron gun to a fluorescent screen of a color picture tube. Therefore, the shape and the diameter of each through hole 5 to be formed on the shadow mask 1 and the shape of the concave portion 3, particularly the contour shape and the outer diameter of the outer peripheral portion of the concave portion 3 are determined in the design stage before the shadow mask is manufactured. The shape and diameter are set in advance so that when the shadow mask is incorporated in a color picture tube or the like, the color picture tube or the like can exhibit desired performance.

Therefore, after manufacturing the shadow mask, an inspection is performed to determine whether or not the formed pattern is a desired pattern. Since a large number of through holes 5 are formed in the shadow mask 1 as a pattern, and the inspection with the naked eye takes time, the inspection of the shadow mask is often performed automatically using a machine.

That is, as shown in the example of FIG. 4, light such as a high-frequency fluorescent lamp or the like is applied to the inspection site of the shadow mask 1 placed on a light-transmissive or frame-shaped inspection table 7 having an opening. Light is emitted from the irradiating means 8, and the light passing through the through-hole 5 formed in the inspection site is measured by, for example, a solid-state imaging camera or the like provided on the side opposite to the light irradiating means 8 with the shadow mask 1 interposed therebetween It is received as a light image by the means 9. Next, after converting this light image into an electric signal, the electric signal is received by a judging means 10 composed of, for example, a computer or the like.
Is to determine whether or not has a desired shape and a desired hole diameter.

At the time of inspection using the above-described automatic inspection machine, a comparative inspection method is generally used for the shadow mask 1 having a plurality of through holes 5 arranged according to a predetermined pattern. That is, by comparing the shapes of a plurality of adjacent through-holes 5 in a certain area, a through-hole 5 having a shape and a hole diameter different from those of the other through-holes 5 is extracted as a defect. This is sequentially performed on the image area 11 of the shadow mask in which the through holes 5 are formed. When moving the inspection site, the light irradiation unit 8 and the measurement unit 9 are moved to another inspection site in conjunction with each other by a moving unit (not shown), or the light irradiation unit 8 and the measurement unit 9 are moved. The position is fixed, and the inspection table 7 is moved by a moving means (not shown). The series of inspections and the operation of the moving means are controlled by, for example, the judging means 10.

In the above-described method for inspecting the shape of the through hole 5, the inspection of the concave portion 3 cannot be performed. That is, since the concave portion 3 is a portion where light is blocked and becomes a shadow, the measuring means 9 cannot detect the concave portion 3 as a light image. For this reason,
Inspection of the shape of the concave portion 3 may be performed separately, and it is necessary to additionally provide an inspection unit used for the inspection. That is, similarly to the inspection of the through-hole described above, a measuring unit such as a solid-state imaging camera that receives the shape of the concave portion as an optical image and converts it into an electric signal, and receives the electric signal, and receives the electric signal to form the concave portion 3, particularly, the contour Inspection means for inspecting and determining whether or not the shape is a desired shape, for example, having at least determination means including a computer or the like, is required separately.

However, the above-mentioned inspection means is very expensive, for example, it requires high accuracy in order to inspect a fine pattern formed on a shadow mask.
For this reason, providing two types of inspection means for inspecting the through hole and the concave portion increases the inspection cost, and may increase the manufacturing cost of the shadow mask. Furthermore, since the inspection must be performed twice, it takes time and labor to perform the inspection, and it can be said that the inspection efficiency is low.

[0015]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an inspection method capable of accurately inspecting the shapes of through holes and recesses formed in a shadow mask by a single inspection. It is an object of the present invention to provide inspection and reduce inspection costs and improve inspection efficiency.

[0016]

That is, the present invention relates to a method of inspecting a shadow mask in which a plurality of through-holes formed by concave portions formed on at least one surface of a thin metal plate is provided. First light irradiating means for irradiating light to the shadow mask from the surface side of the second, second light irradiating means for irradiating light to the shadow mask from the other side of the shadow mask, and the second light irradiating means side Located in
Means for measuring the shape of the through-hole and the concave portion based on the light irradiated from the first light irradiation means and passing through the through-hole, and the light irradiated from the second light irradiation means and reflected from the shadow mask And a method for inspecting a shadow mask, comprising: at least means for judging whether or not the shapes of the through-holes and the concave portions have a desired shape from the measurement results. It is a solution to the problem.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings schematically showing an embodiment of a shadow mask inspection method according to the present invention.

As shown in FIG. 1, in the shadow mask inspection method of this embodiment, the shadow mask 1 is placed on a light-transmitting inspection table (not shown) with the large hole side facing upward. doing. Next, on one surface side (lower surface side in the example of FIG. 1) of the shadow mask 1, similarly to the inspection of the through-hole which has been conventionally performed, a light irradiation unit (hereinafter, referred to as a first light irradiation unit 8 a) The shadow mask 1 is irradiated with light from the first light irradiation means 8a (irradiation light 12a). In this embodiment, a high-frequency fluorescent lamp (manufactured by Matsushita Electric Industrial Co., Ltd., trade name “Slimline fluorescent lamp 48 type FLR48T6W”) is used as the first light irradiating means 8a. The distance from the shadow mask 1 is about 50 mm.

Next, as a feature of the shadow mask inspection method of the present invention, a light irradiating means (hereinafter referred to as a second light irradiating means 8b) is provided on the other surface side of the shadow mask 1 ( 1, the second light irradiation means
From 8b, the shadow mask 1 is irradiated with light (irradiation light 12b).

On the surface side of the shadow mask 1 provided with the second light irradiating means 8b, for example, a measuring means 9 such as a solid-state image pickup camera is provided. The light 13 and the reflected light 14 reflected from the shadow mask are received as a light image. Incidentally, in the present embodiment, a CCD line sensor camera is used as the measuring means 9.

Next, a judging means 10 comprising, for example, a computer is provided. The light image received by the measuring means 9 is converted into an electric signal, and the electric signal is received by the judging means 10.
The judging means 10 determines the shadow mask 1 based on the electric signal.
Of the through-hole 5 formed in the hole and the second light irradiation means
This is for determining whether or not the shape of the concave portion 3 on the surface side provided with 8b is desired.

A further description will be given below with reference to the drawings. FIG. 2 is a partial sectional view of the shadow mask 1. The shadow mask 1 has through holes 5 and small hole recesses 3 at predetermined intervals.
a, a large hole 3b is formed. With the above-described configuration of the light irradiation unit, the irradiation light 12a from the first light irradiation unit 8a reaches one surface side (the lower surface side in the example of FIG. 2) of the shadow mask, The irradiation light 12a applied to the five portions passes through the through-hole 5 as shown in FIG.
Becomes The transmitted light 13 is imaged by measuring means 9 such as a solid-state imaging camera provided on the other surface side (the upper surface side in the example of FIG. 2) of the shadow mask 1. Next, the irradiation light 12b from the second light irradiation means 8b also reaches the other surface side (the upper surface side in the example of FIG. 2) of the shadow mask 1, and the irradiation light 12b is reflected by the surface of the shadow mask 1. Is what is done. This reflected light 14 is also imaged by the measuring means 9 described above.

Here, the irradiating light 12b applied to the portion other than the concave portion 3 is substantially specularly reflected on the substantially flat surface of the shadow mask 1 to become reflected light 14. As shown in FIG. 1, the reflected light 14 is incident on the measuring means 9 such as a solid-state imaging camera located above. However, the concave portion 3 of the shadow mask 1 and
Irradiation light 12 incident on the defective shape part (X and Y parts in FIG. 2)
“b” reflects obliquely because the incident surface is tapered and has an angle. That is, the light reflected by the concave portion 3 of the shadow mask and the concave portion (X and Y portions in FIG. 2) in which the shape is defective is reflected in an oblique direction, and does not enter the measuring means 9 located above. .
Note that the dotted lines of the X and Y portions in FIG. 2 indicate a predetermined shape to be originally formed, and the Z portion in FIG. 2 indicates an example in which the shape of the through hole 5 is defective. The dotted line in the Z portion indicates the shape of the through hole that should be originally formed.

FIG. 3 is a graph showing a partial cross-sectional view of FIG. 2 in which a light image obtained by capturing an image by the measuring means 9 is converted into a voltage and the voltage is obtained from each part. is there.
In the example of FIG. 3, the voltage is high at a portion where light enters the measuring unit 9, and the voltage is low at a portion where light does not enter. That is, the portion where the voltage value is K in FIG.
The shadow mask portion (concave portion) that did not reflect light to the measuring means 9, the portion having a voltage value of L was a substantially flat shadow mask surface portion that reflected light to the measuring device 9, and the voltage value was L. The portions of M indicate through-hole portions, respectively. In addition, the voltage value L of the shadow mask surface portion is
The reason why the voltage value is lower than the voltage value M at the through-hole portion is that the light reflectance on the surface of the shadow mask used in the example was low.

Here, the waveform showing the voltage change obtained from the portion A which is a region where there is no shape defect in FIG. 2 is the portion A in FIG. 3, and the shape defective portions X, Y and Z portions in FIG. The graph diagram parts obtained from the included region are the x, y, and z parts in FIG. 3, respectively.

In the case where there is no defective shape portion shown in the example of FIG. 2, the graph obtained in FIG. 3 shows the waveform of A in FIG. 3 repeated. However, in FIG. 2, there are defective shape portions (X, Y, and Z portions), and in the graph of FIG. 3, the waveform obtained from the region including the defective shape portion (x, y, and z portions) is , The waveform is different from the waveform A obtained from the part having the predetermined shape.

When the judging means 10 detects a portion having a different waveform as described above, a portion in which the shape of the shadow mask is defective, that is, a portion in which the contour shape of the through-hole and the concave portion is defective. Can be detected.
When detecting portions having different waveforms, in the shadow mask 1 having a plurality of through holes 5 arranged according to a predetermined pattern, it is possible to use the comparative inspection method described in the above section (prior art). desirable.

In the shadow mask inspection method of the present invention, the positional relationship between the pair of the first and second light irradiation means 8 may be upside down. However, when the shadow mask is incorporated into a color picture tube or the like, the large hole concave surface side is incorporated into the electron gun side, and the small hole concave surface side is incorporated into the fluorescent screen side. It can be said that it is important for correctly guiding the electron beam to the phosphor screen. Therefore, the first light irradiating means 8a is positioned on the side of the small hole recess 3a of the shadow mask 1, and the second light irradiating means 8b is positioned on the side of the large hole recess 3b of the shadow mask 1, and the large hole recess 3b It can be said that it is desirable to perform the inspection of the contour shape.

As described above, in the shadow mask inspection method of the present invention, the light reflected from the shadow mask is also used for the inspection, and it can be said that the higher the intensity of the reflected light, the more desirable. This is because, as the amount of reflected light incident on the measuring means 9 increases, the difference between a concave portion or a defective shape portion which becomes a dark portion due to oblique reflection of light and a flat surface which becomes a light image by regularly reflecting light becomes clearer. This is because the outer peripheral shape of the concave portion can be easily grasped, and the inspection accuracy increases.

However, the light reflectance on the surface of the shadow mask is, for example, about 70%. When the light is reflected from the shadow mask, the reflected light is attenuated, so that the light intensity is reduced and the shape of the concave portion is clearly formed. May not be caught.

Therefore, in this embodiment, as shown in FIG.
The second light irradiating means 8b is a substantially H-shaped fluorescent lamp (trade name “Palook fluorescent lamp FHL6EX-N” manufactured by Matsushita Electric Industrial Co., Ltd.) having two cylindrical light emitting portions 15 and emits light. Part 15
The measurement means 9 is positioned on the slit between the two, and the longitudinal direction of the CCD line sensor camera and the longitudinal direction of the slit are substantially parallel.

A second H-shaped fluorescent lamp,
That is, by using two light emitting units and increasing the irradiation light amount,
The light quantity incident on the shadow mask 1 increases. As the amount of incident light increases, the intensity of the reflected light 14 incident on the measuring means 9 also increases, and the contour of the recess 3 can be clearly grasped. Furthermore, by using a substantially H-shaped fluorescent lamp,
The transmitted light 13 and the reflected light 14 can pass through the slit between the light emitting units 15 and can reach the measuring means 9 without being blocked by the light irradiating means. In addition,
It is desirable that the distance between the substantially H-shaped fluorescent lamp and the shadow mask be as close as possible in order to increase the amount of light applied to the shadow mask 1. By the way, in this embodiment, the luminous body
The distance between 15 and the shadow mask 1 is about 5 mm.

Next, as a matter of course, it can be said that it is desirable to position the second light irradiating means 8b between the measuring means 9 and the shadow mask 1. This is because, when the measuring means 9 is located between the second light irradiating means 8b and the shadow mask 1, the measuring means 9 blocks the irradiation light 12b from the second light irradiating means 8b, and Shadows appear on
This is because the inspection accuracy deteriorates. Incidentally, in this embodiment, the distance between the measuring means 9 and the shadow mask 1 is about 450 mm. However, the measuring means 9 and the shadow mask 1
Is not limited to this, and the size of the shadow mask 1 area to be inspected at a time, the measuring means 9
It can be said that it is desirable to appropriately set according to the viewing angle, the focusing distance of the measuring means 9 and the like.

The embodiments of the present invention are not limited to the above-described drawings and description, and it goes without saying that various modifications may be made based on the spirit of the present invention. For example, an inspection table on which a shadow mask is placed,
With the frame-shaped inspection table having an opening, the large-hole side is set to the lower surface so that the outer periphery of the shadow mask contacts the frame, and the opening of the inspection table is located in the inspection area of the shadow mask. A shadow mask may be placed on the inspection table. In this case, it is desirable that the first light irradiating means 8a is located on the upper surface side of the shadow mask, and the second light irradiating means 8b and the measuring means 9 are located on the lower surface side of the shadow mask.

[0035]

As described above, according to the shadow mask inspection method of the present invention, the shape inspection of the through-hole and the concave portion can be accurately performed by one inspection using one inspection means. Become. For this reason, the shadow mask inspection method of the present invention does not require a plurality of expensive inspection means, and has conventionally been a problem. That is, the provision of a plurality of expensive inspection means increases the inspection cost, and thus the shadow mask. This solves the problem of raising the manufacturing cost and the problem that the inspection must be performed in two separate steps, requiring a lot of time and labor for the inspection, and the efficiency of the inspection is poor.

[0036]

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a main part of an embodiment of a shadow mask inspection method according to the present invention.

FIG. 2 is a partially enlarged view showing a main part of one embodiment of a shadow mask inspection method according to the present invention.

FIG. 3 is a graph showing an example of defective portion detection in the shadow mask inspection method of the present invention.

FIG. 4 is an explanatory view showing an example of a conventional shadow mask inspection method.

5A to 5E are explanatory views showing an example of a method of manufacturing a shadow mask in the order of steps.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 shadow mask 2 resist film 3 concave portion 4 etching prevention layer 5 through hole 6 shadow mask material 7 inspection table 8 light irradiation means 9 measurement means 10 determination means 11 image area 12 irradiation light 13 transmitted light 14 reflected light 15 light emitting section

Claims (1)

[Claims] An inspection method of a shadow mask in which a plurality of through-holes formed by concave portions formed on at least one surface of a metal thin plate is provided, wherein light is applied to the shadow mask from one surface side of the shadow mask. First light irradiation means,
The second light irradiating means for irradiating light to the shadow mask from the other surface side of the shadow mask, and located on the second light irradiating means side, passed through the through-hole irradiated by the first light irradiating means. Light and the measuring means for measuring the shape of the through hole and the concave portion based on the light irradiated from the second light irradiating device and reflected from the shadow mask, and the shape of the through hole and the concave portion are determined from the measurement result. A method for inspecting a shadow mask, comprising: at least a determining means for determining whether or not a desired shape is obtained.