JPH10267855A - Method and device for inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect irregularity information (defective cutting) on the surface of base material (base tube) of translucent layer-structure, which is to be inspected, like a photoreceptor drum, and further to detect such defect as flow and projection on the surface of layer-structure together with defective cutting on the surface of base material. SOLUTION: A photoreceptor drum (to-be-inspected) 20 comprises a translucent photoreceptor layer 21 and a base tube 22. A reflected light 30 to an incident light (P polarized light) 10 is introduced to a photo-detector 32 through a lens 31, and then it is transferred to electric signal by the photo-detector 32. Here, when an incident light 10 comprising only p-polarized component is made incident on the specimen 20 at a Brewster's angle (i) shown in an equation i=tan<-1> (n2 /n1 ) (n1 is refraction factor in the air, n2 is refraction factor of the photoreceptor layer 21), it reaches the surface of the base tube 22 with no reflection on the surface of the photoreceptor layer 21. By photoelectric- transferring the reflected light with the photo-detector 32, surface of the base tube 22 can be observed even after the photoreceptor 21 is coated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inspection method and apparatus, and more particularly, to an unevenness of a surface of a semi-transparent layered test object or an underlayer surface, for example, a surface of a photosensitive drum or an element. The present invention relates to a method and an apparatus for detecting a defect or a cutting defect on a pipe surface.

[0002]

2. Description of the Related Art In the case of a photosensitive drum used in a copying machine or the like, it is necessary to visually or visually inspect the appearance of all the photosensitive drums after coating the photosensitive layer. At this time, there is an appearance defect due to a cutting defect generated when cutting the raw tube before coating the photoconductor layer. The poor cutting refers to an unremained portion or excessively removed portion of the raw tube when the tube is cut, resulting in a difference of a certain degree or more from the normal portion. In order to detect this cutting defect, it is only necessary to perform an appearance inspection on all the pipes before coating the photosensitive member, but in such a case, two times including the inspection after the photosensitive member coating are performed. It is necessary to perform a visual inspection, and the production efficiency becomes very poor.

[0003] As a method of inspecting the circumferential surface for flaws, Japanese Patent Laid-Open No.
-169840 (Circumferential surface flaw inspection method and apparatus)
According to the method described in this publication, it is possible to inspect the surface of the photosensitive member for scratches, but it is difficult to detect the unevenness of the surface of the tube.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides, for example, information on unevenness of a base surface of a translucent layered test object such as a photosensitive drum. , And further, detecting cutting defects,
The purpose of the present invention is to detect defects such as scratches and protrusions on the surface of the layer structure simultaneously with defective cutting of the surface of the underlayer.

[0005]

According to a first aspect of the present invention, a p-polarized light is incident at a Brewster's angle on the surface of an object having a translucent layer structure, and the reflected light is received to receive the object. Inspection of the surface of the underlayer of the object is performed, and the inspection of the surface of the underlayer of the test object having a translucent layer structure can be performed by making the p-polarized light incident at the Brewster angle. It was made.

According to a second aspect of the present invention, p-polarized light is deflected using a deflecting mirror and an fθ lens, and p-polarized light is applied to the entire region of the translucent layer-structured test object using only the central portion of the effective scanning width. Injecting light at a Brewster's angle, receiving the reflected light with a light receiver, and inspecting the surface of the underlayer of the test object, thereby deflecting optics using a deflecting mirror (polygon mirror) and an fθ lens. By using only the center of the effective scanning width portion in the system, light can be made incident on the entire surface of the test object at a Brewster angle.

According to a third aspect of the present invention, a p-polarized light is deflected by using a deflecting mirror and a lens disposed at a position apart from the deflecting mirror by a focal length, so as to cover the entire area of the test object having a translucent layer structure. p-polarized light is incident at a Brewster's angle, and the reflected light is received by a light receiver to inspect the underlying surface of the object to be inspected, whereby only a deflecting mirror (polygon mirror) and a focal length therefrom. By configuring the deflection optical system with a separate lens, it is possible to make light incident on the entire surface of the test object at a Brewster angle.

According to a fourth aspect of the present invention, in the second or third aspect, the scanning direction of the light and the direction of the cutting streak of the test object are made parallel, and the direction of the cutting streak is determined based on a signal obtained by the light receiver. Calculates the average amount of received light and detects cutting defects based on the magnitude of the average value, so that the direction of cutting streaks on the surface of the underlayer of the translucent layered test object and the scanning direction of light are parallel. By calculating the average amount of received light in the cutting streak direction from the obtained signal, it is possible to detect a cutting defect.

The invention of claim 5 is the invention of claim 2 or 3 or 4
In the invention, the scanning direction of the light and the direction of the cutting streak of the test object are made parallel, and after removing the periodic cutting streak signal from the signal obtained by the photodetector by a filter operation, the translucent layer structure is obtained. It is characterized in that defects on the surface of the test object are also detected at the same time as cutting defects, and thus, by removing periodic cutting streak signals by a filter operation, defects on the surface of the test object with a semi-transparent layer structure are removed from the underlayer. This makes it possible to simultaneously detect surface cutting defects.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION In the following, embodiments of the present invention will be described with reference to an example of a photoreceptor as a test object.
The test object is not limited to the photoreceptor.

(Invention of Claim 1) FIG. 1 is a schematic view of a main part for explaining the invention of claim 1, wherein 10 is incident light (p-polarized light), 20 is a test object, In the illustrated example, the translucent photoreceptor layer 21 and a part of the element tube 22 are shown in an enlarged manner. Reference numeral 30 denotes reflected light. The reflected light 30 is guided to a light receiver 32 through a lens 31, and is converted into an electric signal by the light receiver 32.

FIG. 2 is a diagram showing the polarization characteristics (n ₁ = 1.0, n ₂ = 1.5) of the reflected light from the glass surface. The polarization characteristics of the reflected light are as shown in FIG. Has characteristics. Here, the incident angle at which the reflectance (R _p ) of the p-polarized component becomes 0 is called the Brewster angle (i), the refractive index in air is n ₁ , and the refractive index of the photoconductor layer is n _2. It is obtained by the formula. i = tan ⁻¹ (n ₂ / n ₁ ) Equation (1) Therefore, as shown in FIG.
When the light 10 having only the polarization component is incident on the test object 20, the light reaches the surface of the raw tube 22 without being reflected at all on the surface of the photoreceptor layer 21. If the reflected light is photoelectrically converted by the light receiver 32, even after the photoreceptor 21 is applied, the raw tube 2
2 can be observed.

(Invention of Claim 2) FIG. 3 is a view showing an example of an apparatus configuration (invention of Claim 2) for realizing the invention of Claim 1, and FIG. Conceptual diagram, Figure 3
(B) is a conceptual diagram viewed from above. The light from the laser light source 11 is converted into only the p-polarized light component using the polarization beam splitter 12 and the light is converted into a polygon mirror (deflection mirror) 13.
Then, the light is deflected using the fθ lens 14 and is incident on the test object 20 at a Brewster angle using the reflection mirror 15 as shown in FIG. In this case, as shown in FIG. 3A, when the test object 20 is viewed from the side, the light is incident on the entire test object at a Brewster angle. However, FIG.
As shown in (2), when the test object 20 is viewed from above, the light enters vertically at the center of the effective scanning width of the polygon mirror, but the incident angle shifts as the distance from the center increases. That is, at the end of the effective scanning width of the polygon mirror, the incident angle is
It cannot be said that the Brewster angle is as shown in FIG. Therefore, as shown in FIG. 3B, a mask 16 or the like is provided between the polygon mirror (polygon scanner) 13 and the test object 20 so that the central portion of the effective scanning width, that is, the incident angle is the Brewster angle. Is used as the inspection range. Then, the light reflected from the base surface in that range is condensed by the lens 31 and
2 performs photoelectric conversion. In addition, the entire surface can be inspected by moving with a driving device in the X and Y directions (not shown).

(Invention of Claim 3) FIG. 4 is a view showing an example of an apparatus configuration (invention of claim 3) for realizing the invention of claim 1, wherein light from a laser light source 11 is polarized by a polarizing beam splitter. Then, only the p-polarized light component is used by using the polygon mirror 12, and the light is irradiated onto the test object 20 by using the polygon mirror 13 and the scan lens 17 having the focal length f. Here, as shown in FIG. 4, the reflection point of the polygon mirror 13 and the scan lens 17
Is the focal length f of the scan lens 17,
The light deflected by the polygon mirror 13 is emitted from the scan lens 17 in the same direction. The parallel light is incident on the test object 20 at a Brewster angle using the reflection mirror 15. Thereby, the incident angle can be set to the Brewster angle in the entire inspection range L. In this case as well, the entire surface can be inspected by moving it with a driving device in the X and Y directions (not shown).

(Invention of FIG. 4) When the inspection is performed by using the apparatus shown in FIGS. 3 and 4 with the light scanning direction and the cutting line direction of the raw tube parallel, the obtained signal is as shown in FIG. become. That is, the amount of received light increases in some places due to the change in unevenness due to the cutting of the surface of the base tube, and decreases in some places. Such a cutting defect, if present, usually occurs as a streak in the X direction all around.
Since the cutting streak is almost periodic, the obtained signal also has a bright and dark stripe pattern corresponding to the cycle of the cutting streak as shown in FIG. First, the average light amount in the X direction at each point in the Y direction is calculated based on the data in FIG. 5, as shown in FIG. Here, the cutting defect to be detected is one in which a difference between the normal portion and the normal portion is equal to or more than a certain value due to uncut or excessively cut. If there is a cutting defect, the amount of light increases or decreases as compared with the normal part. Therefore, FIG.
As shown in, threshold levels 1 and 2 are provided, and when the threshold level 1 is exceeded or the threshold level 2
It is determined that the cutting is abnormal when the value is less than. According to this signal processing method, since the data is averaged in the direction of the cutting streak, it is possible to remove the influence of noise due to fine foreign matter or the like.

In the scanning method shown in FIG.
Assuming that the rotation angular velocity of the third lens is ω, the rotation angle is θ, and the focal length of the scan lens is f, the scanning speed on the test object 20 is as shown in FIG. 7 from the equations (2) and (3). That is, FIG.
As shown in (1), the scanning speed is higher at the end than at the center, and the sampling pitch is coarser at the end than at the center. Generally, if there is only one cutting defect, it occurs as a single streak on the entire circumference. Further, when the signal processing is performed by the present method, the difference in the sampling pitch does not cause any particular problem because the average light amount is calculated in the streak direction (X direction).

[0017]

(Equation 1)

(Invention of claim 5) When an inspection is performed by the apparatus of claim 2 or 3, a defect 20a such as a scratch or a projection is actually formed on the surface of the test object 20 as shown in FIG. When there is, the incident light 10 is scattered, the scattered light 10a is received by the light receiver 32, and a point-like defect signal appears in the cutting streak, and a photoconductor surface defect or a tube defect as shown in FIG. Image data representing 20b is obtained. First, based on the original image data, the raw pipe 22 is obtained by the method according to the fourth aspect of the present invention.
Detects cutting defects. Next, returning to the original image (FIG. 10), a filter calculation process for removing periodic cutting streaks is performed, and then a defect enhancement process such as a differentiation process and a binarization process are performed. Defects on the body surface can also be detected.

By the way, as described in the fourth aspect of the invention, in the scanning method of the third aspect, as described in FIGS. 7 and 8, the scanning speed on the test object 20 differs depending on the location. In the case of defect inspection, pass / fail judgment may be made depending on the size of the defect. However, if the size is directly calculated from the original image (FIG. 10), the sampling pitch in the X direction is not constant, so that the size in the X direction cannot be calculated correctly. Therefore, first, the original image (FIG. 10)
I will compress only the direction. The compression ratio is determined from the equation (3) indicating the scanning speed in FIG. 7, and the compression ratio is increased toward the center. As a result, an image sampled at the same sampling pitch as shown in FIG. I do. If the subsequent processing is the same as described above, the size can be calculated correctly.

[0020]

According to the first aspect of the present invention, p-polarized light is incident on the surface of a test object having a translucent layer structure at a Brewster's angle, and the reflected light is received, whereby the underlayer of the test object is received. Since the surface inspection is performed, the surface of the underlayer of the semi-transparent layer-structured test object can be inspected by making the p-polarized light incident at the Brewster angle.

According to a second aspect of the present invention, p-polarized light is deflected by using a deflecting mirror and an fθ lens, and p-polarized light is applied to the entire region of the semi-transparent layered test object using only the central portion of the effective scanning width. Since the light is incident at a Brewster angle and the reflected light is received by a light receiver to inspect the surface of the underlayer of the object, a deflection optical system using a deflection mirror (polygon mirror) and an fθ lens is used. By using only the center of the effective scanning width portion, light can be incident on the entire surface of the test object at a Brewster angle.

According to a third aspect of the present invention, a p-polarized light is deflected by using a deflecting mirror and a lens disposed at a position separated by a focal distance from the deflecting mirror, so that the entire area of the test object having a semi-transparent layer structure is irradiated. The p-polarized light is incident at a Brewster angle, and the reflected light is received by a light receiver to inspect the underlying surface of the object to be inspected. By configuring a deflection optical system with a lens, light can be incident on the entire surface of the test object at a Brewster angle.

According to a fourth aspect of the present invention, in the second or third aspect, the scanning direction of the light and the direction of the cutting streak of the test object are made parallel to each other, and the direction of the cutting streak is determined from a signal obtained by the light receiver. Since the average received light amount was calculated and the cutting defect was detected from the average value, the direction of the cutting streak on the surface of the underlayer of the translucent layered test object and the scanning direction of the light were parallelized. By calculating the average amount of received light in the direction of the cutting streak from the signal obtained, it is possible to detect a cutting defect.

The invention of claim 5 is the invention of claim 2 or 3 or 4
In the invention, the scanning direction of the light and the direction of the cutting streak of the test object are made parallel, and after removing the periodic cutting streak signal from the signal obtained by the photodetector by a filter operation, the translucent layer structure is obtained. Since the defect on the surface of the test object is also detected at the same time as the cutting failure, the periodic cutting streak signal is removed by a filter operation, so that the defect on the surface of the semi-transparent layer structure test object can be detected on the surface of the underlayer. It can be detected simultaneously with cutting failure.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a main part for describing the invention of claim 1;

FIG. 2 is a diagram showing polarization characteristics of light reflected from a glass surface.

FIG. 3 is a diagram showing an example of a device configuration for realizing the invention of claim 1 (the invention of claim 2).

FIG. 4 is a diagram showing another example of the device configuration for realizing the invention of claim 1 (the invention of claim 3).

FIG. 5 is a diagram showing an unevenness signal due to cutting of the surface of the raw pipe.

FIG. 6 is a diagram showing an average light amount in the X and Y directions based on the data of FIG.

FIG. 7 is a diagram for explaining a light inspection speed on a test object.

FIG. 8 is a diagram for explaining a change in scanning speed on a test object.

FIG. 9 is a diagram for explaining scattered light when the surface of the test object has a defect.

FIG. 10 is a diagram showing image data when a defect is present on the surface of the test object.

FIG. 11 is a diagram showing a state in which the size of the defect shown in FIG. 10 is corrected.

[Explanation of symbols]

Reference Signs List 10: incident light (p-polarized light), 11: laser light source, 12: polarization beam splitter, 13: deflection mirror (polygon mirror), 14: fθ lens, 15: reflection mirror, 16: mask, 17: scan lens, 20: Specimen, 20a ...
Defects, 21: photoreceptor layer, 22: base tube, 30: reflected light, 3
1 ... Lens, 32 ... Receiver.

Claims (5)

[Claims] 1. A method of inspecting the surface of an underlayer of a test object by irradiating p-polarized light at a Brewster angle on the surface of the test object having a translucent layer structure and receiving the reflected light. Inspection method to be characterized. 2. A p-polarized light beam is deflected using a deflecting mirror and an fθ lens, and the p-polarized light beam is spread over the entire area of the semi-transparent layered test object using only the central portion of the effective scanning width. An inspection apparatus characterized in that the light is incident at an angle and the reflected light is received by a light receiver to inspect the surface of the underlayer of the test object. 3. A p-polarized light is deflected by using a deflecting mirror and a lens disposed at a position separated by a focal distance from the deflecting mirror, and the p-polarized light is applied to the entire region of the semi-transparent layer structure test object by Brewster. An inspection apparatus, wherein the light is incident at an angle, and the reflected light is received by a light receiver to inspect a base surface of the inspection object. 4. The method according to claim 2, wherein the scanning direction of the light and the direction of the cutting streak of the test object are made parallel, and an average amount of light received in the cutting streak direction is calculated from a signal obtained by the light receiver. An inspection device that detects a cutting defect from the magnitude of the average value. 5. The method according to claim 2, wherein the scanning direction of the light is made parallel to the direction of the cutting streak of the test object, and a periodic cutting streak signal is filtered from a signal obtained by the photodetector. An inspection apparatus for detecting a defect on a surface of a test object having a translucent layered structure after removing by using the method.