JPH1031392A - Method for inspecting surface of photoreceptor base material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To confirm a very minute defect by radiating a laser beam in a spot state to the surface of a drum-like photoreceptor base material along the center shaft of the drum from an oblique direction and detecting scattered light from the surface. SOLUTION: While the drum base material 1 is rotated at fixed circumferential speed by a rotating motor 2, a laser light source 3 and a photoelectric conversion element 4 are moved in the shaft direction of the base material 1 at the fixed speed by a moving stage 5. A distance by which the stage 5 is moved while the base material 1 is rotated once is made smaller than the spot diameter of the laser beam, desirably, equal to or under the half of the spot diameter, so as to uniformly scan all the positions of the surface of the base material. While scanning, an electrical signal from the element 4 is recorded by a data processing part 5. In the case the defect exists on the base material 1, the electrical signal from the element 4 is increased by the scattered light from the defect, so that the defect is detected according to the change of the signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting the surface of a drum-shaped photosensitive member substrate for an electrophotographic photosensitive member.

[0002]

2. Description of the Related Art A photosensitive member used in an electrophotographic copying machine, printer, or the like has a photosensitive layer coated on a conductive base material such as aluminum. In the manufacturing process of the photoreceptor, if the surface of the base material before coating the photosensitive layer has defects such as protrusions, dents and scratches having a size of several μm or more, defects occur in the photosensitive layer and white spots and black spots. Image quality is deteriorated.

Conventionally, a method for inspecting the surface of a photoreceptor has been described.
There has been proposed a method of illuminating the surface of a photoreceptor, detecting the light reflected from the surface with a CCD camera, and performing image processing (Japanese Patent Laid-Open No. 61-7406). Further, a method has been proposed in which laser light is optically scanned in the axial direction of a photosensitive drum by a polygon mirror to detect scattered light from defects (Japanese Patent Application Laid-Open No. 60-86405).

[0004]

However, all of the above methods are applied to the surface inspection of the photoreceptor after the photosensitive layer is coated, and the size of the defect which can be detected by those methods is increased. Is several tens μm or more, and several μm
However, there is a problem that the method cannot be applied to the inspection of the surface of the photoreceptor base material which requires the detection of a minute defect from the size.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in the prior art, and an object of the present invention is to detect minute defects on the surface of a photoreceptor substrate with high accuracy. It is to provide a simple surface inspection method.

[0006]

Means for Solving the Problems In order to achieve the above object of the present invention, as a result of intensive studies, the present inventor has found that the surface of a drum-shaped photoreceptor substrate is obliquely arranged along the center axis of the drum. The present inventors have found that minute defects can be confirmed by irradiating a laser beam with a spot and detecting scattered light from the surface, and have completed the present invention.

That is, in the method for detecting the surface of a photoreceptor substrate according to the present invention, the surface of a drum-shaped photoreceptor substrate is spot-irradiated with a laser beam in an oblique direction along the central axis of the photoreceptor substrate. By moving the laser beam in the axial direction of the photoconductor substrate while rotating the body substrate, the entire surface of the photoconductor substrate is scanned, and scattered light emitted from defects on the surface is detected. And

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a semiconductor laser or a gas laser such as a He-Ne laser is preferably used for spot irradiation, and the spot diameter is 100 μm.
The following are preferably used:

When a laser beam is spot-irradiated on the surface of the photoreceptor substrate from an oblique direction, and the surface is scanned, if a defect is present on the surface, the irradiation light is scattered by the defect. Therefore, if the scattered light is detected by the photoelectric conversion means provided at a position deviated from the regular reflection position of the laser light, a defect existing on the surface of the base material can be detected. In order to accurately detect minute defects, it is important that the incident angle of the laser beam does not change due to scanning. For this purpose, the surface of the drum-shaped photoconductor substrate may be irradiated with laser light from an oblique direction, and the photoconductor substrate may be moved in the axial direction while rotating, thereby scanning the entire surface of the substrate.

Further, since the size of the defect has a correlation with the photoelectric conversion signal detected by the photoelectric conversion means, it is necessary to compare the signal level with a preset signal level and detect only a larger signal. It is possible to detect a defect having a size larger than the size of the defect.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is an example of an apparatus for implementing the present invention. In FIG. 1, reference numeral 1 denotes a drum-shaped photoconductor substrate (hereinafter abbreviated as “drum substrate”), which is rotated by a motor 2. Reference numeral 3 denotes a laser light source for irradiating a laser beam with a spot on the drum surface. In the embodiment shown in this figure, a commercially available semiconductor laser collimator having a condenser lens at the tip is used. Reference numeral 4 denotes a photoelectric conversion element for detecting scattered light, and a photomultiplier is used in the embodiment shown in FIG. The laser light source 3 and the photoelectric conversion element 4 are configured to be movable in the central axis direction of the drum substrate by the moving stage 5. Reference numeral 6 denotes a data processing unit.

FIG. 2 is an explanatory diagram showing the positional relationship between the laser light source 3 and the photoelectric conversion element 4 in FIG. The laser light source 3 can detect a smaller defect as the angle (α) with respect to the center axis of the drum substrate becomes smaller.
It is preferable that the angle is from 0 ° to 60 °, particularly from 0 ° to 30 °. Further, the photoelectric conversion element 4 is installed at a position where the angle (β) with respect to the center axis of the drum deviates from the optical path of the regular reflection light of the laser light, and particularly, up to 90 ° from the optical path of the regular reflection light of the laser light. , That is, α <
It is preferable to provide them so that β ≦ 90 °.

The spot diameter of the laser beam on the drum substrate is adjusted by the condenser lens at the tip of the semiconductor laser collimator. The smaller the spot diameter, the smaller the defect can be detected. Diameter is 100 μm
The thickness is preferably 50 μm or less.

In the case of inspecting the drum substrate by the surface inspection apparatus having the above configuration, the laser light source 3 and the photoelectric conversion element 4 are moved while the drum substrate 1 is rotated at a constant peripheral speed by the rotary motor 2. To move the drum substrate in the axial direction at a constant speed. The moving distance of the moving stage 5 during one rotation of the drum substrate 1 is set to be smaller than the spot diameter of the laser beam, preferably equal to or smaller than half the spot diameter. Scan all positions uniformly. During this time, the photoelectric conversion element 4
Are recorded by the data processing unit 5. When there is a defect on the drum substrate, the electric signal of the photoelectric conversion element 4 increases due to the scattered light from the defect, so that the defect can be detected based on this signal change.

FIG. 3 is a graph showing the relationship between the size of a defect and the size (scattered light intensity) of an electric signal of the photoelectric conversion element due to light scattered from the defect. Note that the graph of FIG. 3 shows that the setting angles of the laser beam and the photoelectric conversion element are set to α = 20 ° and β = 75 °, respectively, and that the laser beam spot diameter on the drum substrate is 30 μm. It was created in.

As can be seen from FIG. 3, the magnitude of the electric signal of the photoelectric conversion element has a correlation with the magnitude of the defect. Further, the size of the detectable defect was 2 μm or more in view of the S / N ratio of the signal. Therefore, according to the present invention, the size of the defect can be specified by comparing the signal level with a preset signal level. Therefore, by setting the detection level to a specific size and detecting a signal change of an unacceptable size (for example, 5 μm or more), the number of defects of an unacceptable size can be accurately measured. It is.

The present invention is intended to measure a drum-shaped photoreceptor substrate, but can be applied to any drum-shaped substrate other than the photoreceptor substrate. It is.

[0018]

According to the present invention, since it has the above structure, a minute defect of about several μm existing on the surface of the drum-shaped substrate can be detected with high accuracy. If the signal level is set in advance, it is possible to accurately detect only a defect having a predetermined size.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an apparatus for carrying out the present invention.

FIG. 2 is a diagram illustrating a positional relationship between a laser light source and a photoelectric conversion element in FIG.

FIG. 3 is a graph showing the relationship between the size of a defect and the intensity of scattered light.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Drum-shaped photoreceptor base material (drum base material) 2 ... Rotation motor 3 ... Laser light source 4 ... Photoelectric conversion element 5 ... Moving stage 6 ... Data processing part.

Claims (2)

[Claims] 1. A laser beam spot irradiation is performed on a surface of a drum-shaped photoreceptor base material obliquely along a central axis of the photoreceptor base material, and the laser light is irradiated while rotating the photoreceptor base material. A method for inspecting the surface of a drum-shaped photoconductor substrate, comprising scanning the entire surface of the photoconductor substrate by moving the material in the axial direction, and detecting scattered light generated from defects on the surface. . 2. The method for inspecting the surface of a photoconductor substrate according to claim 1, wherein the size of the defect is specified by comparing the detected amount of scattered light with a preset level.