JPH11297198A - Shadow mask inspection method and inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically, correctly, easily detect defects of the hole of a shadow mask by masking a mask signal holding the brightness peak value of its signal in the signal of a hole part to form a differential signal, and processing the differential signal. SOLUTION: Light transmitted through a hole and its periphery of a shadow mask 107 is inputted in a measuring instrument 104 as an image. An output signal from the measuring instrument 104 is A/D converted. A calculation processing means 105 forms a mask signal holding the brightness peak value of a signal in a hole part from the signal in the hole part of the converted signals by using mathematical form processing. By masking the mask signal in the signal in the hole part, a differential signal is formed. In the differential signal, the ratio occupying in the differential signal of a signal of the edge part of the original hole for judging defects is made larger than the ratio of the signal of the edge part of the original hole occupying in the signal of the original signal to emphasize the judging information of defects. The processing result of the differential signal is displayed on a display device 106.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask inspection method and an inspection apparatus used for a cathode ray tube, and more particularly to a shadow mask inspection method and an inspection apparatus which can inspect spots and unevenness of a shadow mask.

[0002]

2. Description of the Related Art In a shadow mask manufactured by a photo-etching method using a thin metal plate, the hole of the shadow mask may be manufactured in an abnormal state due to some cause during the manufacturing process of the shadow mask. FIG. 8 shows this phenomenon, that is, the state where the hole of the shadow mask is not normal. For example, FIG. 8A has a protrusion to the hole (a part of the edge of the hole, in which the metal sheet to be the hole is not etched), and is called a hole protrusion. FIG. 8 (b) shows a case where the edge of the hole is chipped (a part of the edge of the hole is a thin metal plate in the periphery of the hole etched), which is referred to as a chipped hole. In FIG. 8C, the diameter of the hole is larger than the target, and is called a hole size. In addition, FIG.
Are smaller in diameter than the target, and are called small holes. In FIGS. 8A to 8D, the dotted lines indicate the target of the hole diameter.

The difference between the shape and size of the hole and the target as described above depends on whether or not the degree of the difference affects the quality of a shadow mask as a product. Generally, when the shape and size of the holes are significantly different from the target, each of the holes constituting the shadow mask appears as one defect. That is, when any of the phenomena shown in FIGS. 8A to 8D is significantly different from the target in shape and size, each defect is regarded as one defect on the screen of the shadow mask. Alternatively, it appears as a plurality of defects in a dot-like light and dark state.

[0004] Specifically, the degree of the difference between the target and the shape and size is, for example, about 100 µm in diameter, and the hole projection shown in Fig. 8A is about 10 µm. Such a defect having a remarkable difference from the target is treated as a shape defect, and since the difference from the target is remarkable, the difference between the transmitted light quantity and the detection of the defect in the defect detection is clearly different. Recognized and relatively easy to detect,
Various automatic inspection techniques have been developed.

On the other hand, when the difference in shape and size of the hole from the target is very small, each of the holes constituting the shadow mask does not appear as a single defect. That is, each of them does not appear as a dot on the screen of the shadow mask as a single defect. However, when a large number of small holes having differences are gathered adjacent to each other, some of them appear as another defect. Such a defect that appears when a large number of holes having a small difference from the target gather adjacently is treated as an appearance defect.

As defects in appearance, for example, spots and unevenness are called. Defects called spots appear on the screen of a shadow mask as bright spots and dark spots like spots stained on the appearance. This spot appears at one or several places in the screen of the shadow mask, and has a size of, for example, about 5 mm in diameter. Such a phenomenon appears when, for example, many dozens or more of holes constituting a shadow mask and having a small difference from a target are adjacent to each other and are gathered.

[0007] Further, a defect called unevenness appears on the screen of a shadow mask in an uneven state of brightness, such as uneven clouds, bright uneven clouds, and dark uneven clouds. Things. This unevenness appears on a part or most of the screen of the shadow mask, and is, for example, about several tens mm in diameter. Such a phenomenon appears when a large number of holes that constitute a shadow mask and have a small difference from the target are, for example, several hundred or more adjacent to each other.

The appearance defects called spots and unevenness that appear when a large number of small holes having a difference from the target in the shape and size of the holes as described above appear adjacently are shadow masks. It is difficult to measure the minute difference and detect it as a defect because the difference between the shape and the size of each hole is very small. Specifically, the degree of the difference between the target and the shape or size is, for example, about 100 μm.
It has a diameter of about 1 μm or less.

At the present time, a method for automatically and accurately inspecting spots and unevenness as defects has not been established, and such external defects have to rely on visual inspection. Further, the visual inspection has disadvantageous problems such as a large amount of labor for the inspector, quantitative / stability of the inspection standard such as variation in judgment by the inspector, and time and cost of the inspection.

[0010]

SUMMARY OF THE INVENTION As described above, according to the present invention, when a shadow mask is manufactured by a photo-etching method using a thin metal plate, the shadow mask is manufactured due to some cause during the manufacturing process of the shadow mask. The hole is manufactured in a state where the hole is not normal, but the shape, size, etc. of the hole in the shadow mask are significantly different from the target, such as hole projections, missing holes, large holes, small holes, etc. Automatically accurately and easily detect defects, and the shape of the holes in the shadow mask, which was difficult with the conventional technology,
A shadow mask that can automatically and easily detect external defects such as spots and unevenness that appear when a large number of adjacent groups gather, when the size is slightly different from the target. An inspection method and an inspection apparatus are provided.

[0011]

SUMMARY OF THE INVENTION According to the present invention, a luminance peak value of a signal in a hole portion of a shadow mask image and a peripheral portion thereof is obtained from a signal of the hole portion by using mathematical morphological processing or the like. By generating a difference signal by masking the mask signal with the signal of the hole portion and generating the difference signal, and processing the difference signal, it is possible to detect a defect in the hole of the shadow mask. This is a characteristic shadow mask inspection method.

Further, the present invention provides the shadow mask inspection method according to the above invention, wherein the mask signal is an image of an image of a hole of the shadow mask to be inspected and a peripheral portion thereof.
An inspection method of a shadow mask, which is created from a signal of a hole portion. Further, the present invention is the shadow mask inspection method according to the above invention, wherein the difference signal is integrated and processed for each hole.

According to the present invention, there is provided an inspection apparatus for a shadow mask formed by a photo-etching method using a thin metal plate, wherein (a) X, Y, Z
A moving device that moves in the direction and the θ direction; (b) an illumination device that irradiates measurement light for measuring the shadow mask;
(C) an imaging device for forming an image of transmitted light obtained by imaging the hole of the shadow mask and its peripheral portion, (d) a measuring device for measuring the luminance of the image formed by the transmitted light,
(E) A mask signal holding a luminance peak value of the signal of the hole portion is created from the signal of the hole portion of the shadow mask based on the output signal of the measuring device, and the mask signal is masked on the signal of the hole portion. Calculating a difference signal, and processing the difference signal to detect a defect in the hole of the shadow mask and determine a pass / fail state.
(F) A shadow mask inspection device, comprising: a display device for displaying a result calculated by the calculation processing means.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A shadow mask inspection method and an inspection apparatus according to the present invention will be described below based on the embodiments. FIG. 1 is a schematic explanatory view showing one embodiment of a shadow mask inspection apparatus according to the present invention. As shown in FIG. 1, the moving device (102) moves the placed shadow mask (107) in the X, Y, Z, and θ directions. Transport device (not shown), and the moving device (10
2), and is carried out by a right-side transfer device (not shown) after the inspection is completed.

An illumination device (101) for irradiating the shadow mask (107) is arranged below the moving device (102). The illumination device (101) is a surface light source, and the light from the surface light source irradiates the shadow mask (107) located above the light as measurement light. Also,
The imaging device (103) is arranged above the shadow mask (107), and forms an image of the transmitted light transmitted through the holes of the shadow mask (107) and the periphery thereof as an image on the measurement device (104). I have. The measuring device (104) is arranged above the image forming device (103), and includes a light receiving element for measuring the luminance of an image.

The calculation processing means (105) includes a measuring device (1).
The defect of the hole of the shadow mask is calculated based on the output signal from the light receiving element in 04), that is, the signal of the transmitted light transmitted through the hole of the shadow mask (107) and its peripheral portion, and the pass / fail is determined. is there. In addition, the display device (10
6) displays the result calculated by the calculation processing means (105).

FIGS. 2A to 2F are block diagrams showing the processing procedure of the shadow mask inspection method according to the present invention. FIG. 2A shows the shadow mask (10) shown in FIG.
7) A step of inputting the transmitted light transmitted through the hole and its peripheral portion to the measuring device (104) as an image. For example, a linear CCD or an area CCD is used as a light receiving element that measures the luminance of an image.

FIG. 2B shows the measuring device (10) shown in FIG.
4) shows a step of A / D converting an output signal from the light receiving element in 4). FIG. 2C shows that the calculation processing means (105) shown in FIG.
The step of generating a mask signal holding the luminance peak value of the signal of the hole portion from the signal of the hole portion in the output signal from the light receiving element in 4) by using mathematical morphological processing or the like is shown. The mask signal generated to extract the signal of the edge portion of the hole is formed to be a mask signal having a diameter smaller than that of the original hole by about 10 to 30%.

FIG. 2 (d) shows a step of creating a difference signal by masking a signal in the hole portion with a mask signal. In this difference signal, the ratio of the signal of the edge of the original hole to the difference signal, which is used to determine whether or not a defect occurs, is the signal of the edge of the original hole, which is the signal of the original hole. It is larger than the ratio. That is, the information for judging whether or not it is a defect is emphasized.

FIG. 2E shows a step of detecting the defect of the hole of the shadow mask and judging the quality by processing the difference signal. FIG. 2F shows a step of detecting a defect in the hole of the shadow mask and displaying the result of the pass / fail judgment.

In the step of inputting the hole of the shadow mask and its peripheral portion as an image in FIG.
An example of a shadow mask hole for imaging is shown in a plan view in FIG. 3A and a cross-sectional view in FIG. 3B. FIG. 3 (a),
In (b), (a) shows a round hole and (b) shows a square hole. In FIGS. 3A and 3B, the diameter (301, 302) of the opening on the side from which the electron beam is emitted is the diameter (303, 30) of the opening on the side on which the electron beam is incident.
It is larger than 4). The penetrating portions are called shadow mask holes (305, 306). Since light passes through this hole, the luminance is high on the image and the signal is large. Since the portion other than the hole is completely shielded from light, the luminance on the image is low, and the signal is near zero. At the edge of the hole, the signal becomes dull due to the influence of scattered light and the like. For this reason, an area having a luminance equal to or higher than a certain threshold value (5 to 10% of the maximum luminance value) is recognized as a hole.

FIG. 4 (a) shows a signal from the light receiving element which has received the transmitted light transmitted through the round hole (305) in FIGS. 3 (a) and 3 (a) in a cross section XX '. Things. The output signal from the light receiving element in FIG.
Following the step of performing the / D conversion, the step of generating the mask signal of FIG. 2C is performed, as shown in FIG. A mask signal is created by performing mathematical morphological processing or approximating a distribution curve as a function and changing parameters from a signal of a hole having a diameter (W ₁ ) and a signal magnitude (H ₁ ). .

The mask signal to be created is a mask signal holding the luminance peak value of the signal of the hole portion as shown in FIG. 4 (b) whose magnitude (H ₂ ). In order to extract a signal at the edge of the hole, the mask signal is formed into a mask signal having a diameter (W ₂ ) such that the mask has a diameter smaller by about 10 to 30% than that of the original hole. Also, in FIGS. 4A and 4B, reference numerals 401 and 402 denote signals of holes and masks, respectively, in plan views.

The above description is as shown in FIGS.
The mask signal is created from the signal of the hole portion when the shape of the hole of the shadow mask is normal, and the shape of the created mask signal is also normal. FIG.
(A) and (b) show a method of creating a mask signal from a signal of a hole portion in a case where the original hole has a defect such as a hole protrusion or a chipped hole. FIG.
FIG. 5A shows a method of making a mask signal from a signal of a hole portion by performing contraction / expansion of mathematical morphological processing, and FIG. 5B shows a method of making a mask signal from a signal of a hole portion. Is a method of performing expansion and contraction of mathematical morphological processing when generating.

In FIG. 5A, the signal of the hole (501) having the defect of the hole becomes a signal of the hole (502) in which the hole is eliminated by performing the contraction processing (A). The signal of the hole (502) in which the hole is missing is subjected to expansion processing (b) to the diameter of the original hole, so that the signal of the hole (503) having the diameter of the original hole in the hole in which the hole missing has disappeared. Is what you get. Since the signal of the hole (503) has a normal shape, the signal of the hole (503) is used to generate a signal of the normal mask (504) as described above. Can be.

In FIG. 5 (a), the signal of the hole (511) having a hole projection defect remains the signal of the hole (512) in which the hole projection does not disappear even after the contraction process (a) is performed. is there. The signal of the hole (512) that does not disappear from the hole projection is
By performing expansion processing (b) on the diameter of the original hole, a signal is obtained for the hole (513) having the diameter of the original hole in the hole where the hole protrusion has disappeared. Since the signal of the hole (513) has a normal shape, the signal of the hole (513) is used to make the normal mask (51) as described above.
The signal of 4) can be created.

On the other hand, in FIG. 5 (b), the signal of the hole (501) having the defect of the hole chip remains the signal of the hole (505) which does not disappear even if the expansion processing (a) is performed. is there. The signal of the hole (505), which does not disappear, is
By performing the shrinking process (b) on the diameter of the original hole, a signal of the hole (506) having the diameter of the original hole is obtained from the hole where the chipped hole has disappeared. Since the signal of the hole (506) has a normal shape, the signal of the hole (506) is used to make the normal mask (50) as described above.
The signal of 7) can be created.

In FIG. 5B, the signal of the hole (511) having the hole protrusion defect becomes a signal of the hole (515) in which the hole protrusion has disappeared by performing the expansion process (A). The signal of the hole (515) in which the hole protrusion has disappeared is subjected to a contraction process (b) to the diameter of the original hole, and the signal of the hole (516) having the diameter of the original hole in the hole in which the hole protrusion disappears. Is what you get. Since the signal of the hole (516) has a normal shape, the signal of the hole (516) is used to generate a signal of the normal mask (517) as described above. Can be.

As described above, in the present invention, for example, a mask signal prepared from a signal of a hole having a normal shape of a certain shadow mask is prepared in advance as a standard or a reference, and the prepared mask signal is used. Instead of performing a defect detection and pass / fail judgment in comparison with a signal of a hole portion of a shadow mask to be actually inspected, a mask signal to be used is an image of a hole of a shadow mask to be inspected and a peripheral portion thereof. It is characterized by being created from a signal of a hole portion of an image.

The shadow mask inspection method according to the present invention has the following advantages. That is, the interval between the holes in the shadow mask is called a variable pitch (unequally spaced arrangement). The interval between the holes is not uniform, and the interval between the holes varies depending on the position of the hole on the screen. Therefore, in a method in which a mask signal is prepared in advance as a standard or a reference, a separate mask signal is required for each of a plurality of adjacent holes when inspecting the regions.
According to the present invention, since a mask can be created from a hole to be inspected, it is not necessary to hold an enormous amount of mask data, and it is easy to deal with various types.

Next, the masking step shown in FIG. 2D for masking the signal of the hole portion with a mask signal to generate a difference signal is performed by the hole diameter (W ₁ ) in FIG. Then, a mask signal having a diameter (W ₂ ) and a signal magnitude (H ₂ ) shown in FIG. 4B is subtracted from the signal of the hole portion having the signal magnitude (H ₁ ), and FIG.
The difference signal shown in (c) is created. Fig. 4 (c)
, W ₃ is the width of the ring of the created difference signal, H ₃ is the size of the difference signal, and 403 is a plan view of the difference signal.

In this difference signal, the ratio of the signal of the edge portion of the original hole to the difference signal for judging whether or not a defect occurs is determined by the edge of the original hole in the signal of the original hole. It is larger than the ratio of the signal of the section. That is, the information for judging whether or not it is a defect is emphasized.

In FIG. 4C, the region of the difference signal shown in the plan view (403) defines a constant threshold value, and a portion having a value equal to or larger than the threshold value is connected to the connected portion. A method such as recognition as an area is used. Then, by integrating (accumulating) the difference signals in this area,
This is to obtain an integrated signal of one hole. This integrated signal is used as a signal for determining whether or not the single hole or a large number of adjacent holes becomes a defect in the next step, ie, the determination process shown in FIG. What is used. In the determination process, the integrated signal obtained as described above is subjected to, for example, a binarization process and then the determination process is performed.

FIG. 6 is a plan view showing how masking is performed to create a difference signal in a hole having a hole notch or a hole protrusion. The signal of the mask (602) created from the signal of the hole is subtracted from the signal of the hole (601) having a hole, to obtain a difference signal (603). At this time, the difference signal (60
In the case of 3), the signal is larger than that of a normal hole by an amount corresponding to the hole missing portion (604). Further, the signal of the mask (612) created from the signal of the hole is subtracted from the signal of the hole (611) having the hole protrusion to obtain a difference signal (613). At this time, the signal of the difference signal (613) is smaller than that of the normal hole by the projection (614).

As described above, when there is a significant difference between the shape and size of the hole in the shadow mask and the target, each of the holes constituting the shadow mask appears as a single defect. . In this case, the integrated signal of the corresponding hole is either extremely large or extremely small. Therefore, detection of such a shape defect is relatively easy. For example, about 100 μm
In the case of a hole having a diameter, when the hole protrusion shown in FIG. 8A is about 10 μm, the decrease of the integrated signal becomes remarkable corresponding to about 10 μm of the hole protrusion.

However, as described above, the defects referred to as spots and unevenness have small differences in the shape and size of the holes in the shadow mask from the target, as described above. Each one of the holes constituting the mask does not appear as a single defect. In this case, the integrated signal of the corresponding hole is in a state of being slightly large or small. In response to such an appearance defect, the integrated signal of each single hole obtained as described above is used as a set of holes in the arrangement state of the holes constituting the shadow mask, that is, The integrated signal of the holes is set as a set in the arrangement state, and the determination process is performed in the arrangement state.

For example, in the case of a defect called a spot or unevenness, when there is a small difference of about 1 μm or less in a large number of adjacent holes of several tens or hundreds or more. In addition, the increase or decrease of the integrated signal corresponding to the minute difference in the hole diameter is determined by determining whether the defect is a defect in a state where a large number of adjacent tens or hundreds or more are arranged. . The determination result may be displayed on a display device or the like, and may be recorded on an external storage device such as a hard disk as needed.

Here, the transmitted light transmitted through the hole of the shadow mask (107) and its peripheral portion shown in FIG. 1 is input as an image to the measuring device (104), and serves as a light receiving element for measuring the luminance of the image. For example, as for the performance of the CCD, the spatial resolution for resolving the position of the image is 10 μm.
m is desirable, and the luminance resolution for resolving the gradation of the image is preferably as high as 8 to 16 bits. By using a light-receiving element having such a high resolution, a small difference in the shape and size of a hole in a shadow mask in a defect referred to as a spot or unevenness as described above is detected. It is possible to decide whether or not to do so.

As described above, when the difference from the target, such as the shape and size of the hole in the shadow mask, is very small, the stains appear when a large number of adjacent groups are gathered. It is also possible to automatically and easily detect external defects such as unevenness.

An embodiment of the present invention will be described below.

<Embodiment 1> As shown in FIG. 7, a moving device (702) moves a placed shadow mask (701) in X, Y, Z and θ directions. The mask (701) is carried in by, for example, a transfer device (not shown) on the left side, placed on a moving device (702), and unloaded by a transfer device (not shown) on the right side after the inspection.

The illumination device (710) for irradiating the shadow mask (701) is arranged below the moving device (702). The lighting device (710) includes a shadow mask (7).
01) is irradiated with measurement light. The illumination device (710) includes a laser light source (703) and a deflecting element (70).
4), a lens (705) and the like, and adopts a raster scan method. The laser light from the laser light source (703) is raster-scanned in the X direction and moved by the moving device (702) in the Y direction, so that the entire surface of the placed shadow mask (701) is irradiated. I have.

When the laser light from the laser light source (703) has a large divergence angle, the laser light source (703)
A collimator lens is required between 3) and the deflecting element (704). As the deflecting element (704), for example, a polygon mirror, a galvano mirror, or a rotating prism can be used.

The image forming device (706) is arranged above the shadow mask (701), and forms the transmitted light transmitted through the holes of the shadow mask (701) and the periphery thereof as an image on the measuring device (707). I have an image. The imaging device (706) does not necessarily need to be an imaging optical system,
For example, it is also possible to guide light to the measuring device (707) using a mirror having a curved surface such as a quadratic function curved surface.

The measuring device (707) includes an image forming device (70).
6), and is composed of a photodetector for measuring the brightness of an image. For example, a phototransistor or a photomultiplier tube can be used as the photodetector. The calculation processing means (708)
Based on an output signal from the photodetector in the measuring device (707), that is, a signal of transmitted light transmitted through the hole of the shadow mask (701) and a peripheral portion thereof, a defect of the hole of the shadow mask is calculated and pass / fail is determined. Things.

The output signal from the photo detector is A / D
The conversion results in a digital signal. This signal is a time-series signal, and is converted into a two-dimensional image signal by, for example, a method of using a synchronization signal or synchronizing from a theoretical scan speed value. The display device (709) displays the result calculated by the calculation processing means (708).

[0046]

According to the present invention, a luminance peak value of a signal of a hole portion is retained by using a mathematical morphological process or the like from a signal of the hole portion of an image obtained by imaging a hole of a shadow mask to be inspected and a peripheral portion thereof. A mask signal is created, and a mask signal is masked on the signal of the hole portion to create a difference signal. This difference signal is integrated for each hole and processed to detect a hole defect in the shadow mask. Automatically and easily detects geometric defects such as hole protrusions, missing holes, large holes, and small holes when the difference from the target, such as the shape and size of the shadow mask hole, is significant. In addition, when the difference from the target, such as the shape and size of the hole of the shadow mask, is very small, the appearance of spots and unevenness that appears when a large number of adjacent groups gather is difficult with the conventional technology. Automatically accurate and accurate defect detection It can be carried out in. In addition, a shadow mask inspection device for that purpose can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an embodiment of a shadow mask inspection apparatus according to the present invention.

FIGS. 2A to 2F are block diagrams showing processing procedures of a shadow mask inspection method according to the present invention.

FIG. 3A is a plan view of an example of a hole of a shadow mask. (B) is a sectional view of an example of a hole of a shadow mask.

FIG. 4A shows a signal from a light receiving element that has received transmitted light transmitted through a round hole in a cross section taken along line XX ′. (B) is a mask signal holding the luminance peak value of the signal of the hole portion.

FIG. 5A is a diagram showing a method of creating a mask signal from a signal of a hole portion by performing contraction / expansion of mathematical morphological processing. FIG. 6B is a diagram illustrating a method of creating a mask signal from a signal of a hole portion by performing expansion and contraction of mathematical morphological processing.

FIG. 6 is a plan view showing a state of masking for creating a difference signal in a hole having a hole notch or a hole protrusion.

FIG. 7 is a schematic explanatory view of Embodiment 1 of a shadow mask inspection apparatus according to the present invention.

FIG. 8 is an explanatory view showing a state where holes of a shadow mask are not normal.

[Explanation of symbols]

101, 710: Illumination device 102, 702: Moving device 103, 706: Imaging device 104, 707: Measuring device 105, 708: Calculation processing means 106, 709: Display device 107, 701: Shadow mask 301, 302: Electron beam Diameters of openings 303, 304... Diameters of openings on the side where electron beams are incident 305, 306... Holes of shadow mask W ₁ W ₂ ... Diameters of holes, diameters of masks W ₃ . Ring widths H ₁ , H ₂ , H ₃ ... The magnitude of the hole signal, the magnitude of the mask signal, and the magnitude of the difference signal. 501: a hole having a defective hole 502: a hole having a missing hole 503: a hole having a missing hole, the hole having the original diameter 504, 507, 514, 517: a mask 511: a defect of a hole protrusion Holes 512: Holes in which the hole protrusions do not disappear 513: Holes in which the hole protrusions have disappeared and the diameter of the original hole 505 ... Holes in which the hole missing does not disappear 506 ... Holes in which the hole lacking disappears and the original hole diameter Holes 515: Holes with hole protrusions disappeared 516: Holes with hole protrusions disappeared and having the original diameter of the hole 601: Holes with hole cutouts 611: Holes with hole protrusions 602, 612: Created from signal of holes Masks 603, 613: Difference signal 703: Laser beam 704: Deflection element 705: Lens

Claims (4)

[Claims] 1. A mask signal which retains a luminance peak value of a signal of a hole portion of an image obtained by imaging a hole of a shadow mask and a peripheral portion thereof from a signal of the hole portion by using mathematical morphological processing or the like. A shadow mask inspection method comprising: forming a difference signal by masking the mask signal with the signal of the hole portion; and processing the difference signal to detect a defect in a hole of the shadow mask. . 2. The shadow mask inspection according to claim 1, wherein the mask signal is created from a signal of a hole portion of an image obtained by imaging a hole of the shadow mask to be inspected and a peripheral portion thereof. Method. 3. The shadow mask inspection method according to claim 1, wherein the difference signal is integrated and processed for each hole. 4. An apparatus for inspecting a shadow mask formed by a photo-etching method using a thin metal plate, comprising the steps of: (a) placing a shadow mask thereon in the X, Y, Z directions and θ;
(B) an illuminating device for irradiating measurement light for measuring the shadow mask, (c) an imaging device for forming an image of transmitted light obtained by imaging the hole of the shadow mask and a peripheral portion thereof. (D) a measuring device for measuring the brightness of the image formed by the transmitted light, (e) a brightness of a signal of the hole portion from a signal of the hole portion of the shadow mask based on an output signal of the measuring device. Create a mask signal holding the peak value, mask the mask signal to the signal of the hole portion, create a difference signal, and process the difference signal to detect a hole defect in the shadow mask. And (f) a display device for displaying a result calculated by the calculation processing means.