JPH06123707A - Method for inspecting surface defect and its device - Google Patents

Abstract

PURPOSE:To make easy detection of a defect of moderate recesses and projections of a surface on which a uniform membrane is applied to a base of metal and the like by detecting a change of an axial center direction boundary part of a projection light image having an end edge crossing at right angles with an axial center direction formed on the surface of a cylinder. CONSTITUTION:A projector 4 serves to form a belt-like projection light image 6 crossing at right angles with an axial center direction of a cylinder 1 for the surface of the cylinder 1. A light receiver 5 for making a visual field 7 of a boundary part 8 of the projection light image 6 is arranged and serves to receive reflection light in the neighborhood of the boundary part 8 in the visual field 7. In the case where a defect 3 exists on the surface 2 of the cylinder 1, a strain occurs on a projection light image end edge part of the boundary part 8 due to existence of the defect 3 and appears in the output of the light receiver 5. Accordingly a signal corresponding to the strain is analyzed for the purpose of detection of a defect on the surface. As the result, since the neighborhood of the boundary part in the longitudinal direction of the cylinder of the projection image formed on the surface of the cylinder is made a light receiving position of a line sensor constituting the light receiver, the detection of moderate recesses and projections defects of the surface is made easy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface defect inspection of a cylindrical body, and particularly in a coating process of a photosensitive drum used in an image output device such as an electrostatic copying machine or a laser printer by an electrophotographic technique. The present invention relates to a surface defect inspection method and apparatus for inspecting a surface defect.

[0002]

2. Description of the Related Art An intermediate recording body made of a cylindrical body used in a copying machine or a laser printer, that is, a so-called photosensitive drum, is applied to a surface of a photosensitive body during application of a photosensitive material, vapor deposition, and handling during assembly of a photosensitive unit. Defects called "mechanical scratches" that are dents and scratches occur. Since this mechanical flaw appears as an image quality defect such as a black spot or a white spot on a copy, all the surface inspections are performed on the photosensitive drums.

Also, in recent years, O
PC (organic photoconductor) has defects called "coating process defects" that occur in the photoconductor coating process in addition to the above-mentioned defects called "mechanical scratches". FIG. 9 is a cross-sectional view of a main part of the photosensitive drum for explaining various defects occurring on the surface of the photosensitive drum. 1 is the photosensitive drum, 21 is a charge transport layer, 22 is a charge generation layer, and 23 is a lower layer. The pulling layer 24 is an aluminum base. Further, 31 is an exposed aluminum surface, 32 is a change in film thickness, 33 is a foreign matter, and 34 is a surface irregularity.

Mechanical scratches expose the aluminum substrate 24 and cannot function as an intermediate recording medium. The OPC consists of an aluminum substrate 24, an undercoat layer 23, a charge generation layer 22,
The charge transport layer 21 is applied, and the defects that occur in the OPC are "spots", "axis lines", "unevenness", and "patterns" of the charge generation layer 22, depending on the shape and the cause thereof.
There are more than 10 kinds of defects in total, which are classified into the inclusion of metal pieces or other foreign substances into the metal, the change in the film thickness of the charge transport layer 21 (“dent”, “sag”, “bulge”) and the like. The size of these defects is about 0.1 mm to several mm.

FIG. 10 is an explanatory view of various defects that occur on the surface of the photosensitive drum, and the reference numerals correspond to the defective portions shown in FIG. As shown in FIG. 10, among the surface defects,
The change 32 in the film thickness is "spots", "axis lines", "wind ripple patterns".
There are "hail pattern", "scaly pattern", and "step unevenness". The foreign material 33 deteriorates the charge transport property due to the inclusion of metal pieces and other foreign materials, and the surface unevenness is "bulging".
There are "dents" and "axis lines".

In particular, "stain" and "unevenness" defects appear as subtle changes in the hue of the photosensitive drum surface, and "dent" defects appear as subtle irregularities in the mirror surface of the photosensitive drum surface. It can be detected only after observing. The non-uniformity of the film thickness of the photoconductor that occurs in the coating process causes unevenness of the surface potential, resulting in deterioration of image quality especially in halftone copying. Halftone copying is used for photographic originals and is an important function of copying machines. For this reason, inspecting for subtle color unevenness and dents in the photoconductor coating process is becoming increasingly important in terms of quality assurance.

As a method for inspecting a surface defect using a cylindrical body as an object to be inspected, a visual inspection by an inspector has been conventionally performed (for example, see Japanese Utility Model Laid-Open No. 63-54166). However, visual inspection has problems such as variation in inspection quality, increase in inspection man-hours, increase in inspection space, deterioration of work environment due to visual fatigue, difficulty in securing workers, and increase in training time for workers.

Therefore, as a technique for automating the visual inspection work of the surface of the object to be inspected, the following methods and devices have been conventionally proposed. FIG. 11 is an explanatory diagram of a first example of a conventional automatic inspection device for the surface of a photosensitive drum, in which the spot light of a laser 113 is lined up on the surface of the photosensitive drum 111, which is an object to be inspected, via a deflector 114. Scanning is performed, the scattered light due to defects on the inspection surface is collected by the light collector 112, guided by the optical fiber bundle 115, received by the light receiver 116 composed of a photomultiplier tube, and calculated by the calculation means 117 with a predetermined threshold value. Then, the calculation result is displayed on the display means 118 (JP-A-60-86405). However, in this conventional example, there is a problem that interference fringes are generated in the photosensitive layer and the inspection accuracy is lowered.

FIG. 12 is an explanatory view of a second example of a conventional automatic inspection device for the surface of a cylindrical body, in which light of a laser 123 having a predetermined wavelength according to the light absorption characteristics of a photosensitive layer is deflected by a deflector 124. By scanning the surface of the drum 121 and receiving the reflected light from the photosensitive drum 121 by the light receiver 126, the incident angle of the laser light to the photosensitive layer accompanying the scanning of the laser light in the above example is This is to improve the interference fringes that occur when the change is used (Japanese Patent Laid-Open No. 2011-2011).
42 publication).

FIG. 13 is an explanatory view of the wavelength region of the laser used in the conventional example of FIG. 12, in which 100 parts by weight of polycarbonate, 100 parts by weight of diethylaminobenzaldehyde phenylhydrazone, and 8 parts by weight of metal-free phthalocyanine are used as the photosensitive layer. In that case, it is shown that the generation of the interference fringes is suppressed by using a 632.8 nm He—Cd laser source as the laser 123.

FIG. 14 is an explanatory diagram of a third example of a conventional automatic inspection device for the surface of a cylindrical body, in which the surface of the photosensitive drum 141 is illuminated by an illuminating device 143 and the reflected light is imaged by a unity magnification image forming element 14.
5 forms an image on the sensor array 146, and the image processing device 147
The defect data obtained by processing with the surface means 14
No. 8 (Japanese Patent Laid-Open No. 3-54438).

FIG. 15 is an explanatory view of a fourth example of the conventional automatic inspection device for the surface of a cylindrical body, in which 151 is a line sensor and 1 is a line sensor.
52 is a drum drive motor, 153 is dust removal air, 154
Is a light-shielding plate, 155 is a cylinder lens, 156 is an optical fiber, 157 is a halogen light source, 158 is a photosensitive drum as an object to be inspected, 159 is scattered light, 160 is a signal processing device, and 161 is a judgment processing device.

This device is used by the present inventors as an inspection device for a photoconductor drum using the line sensor 151.
No. 64762 and Japanese Patent Application Laid-Open No. 4-70553, the light from the halogen light source 157 is condensed by the optical fiber 156 and the cylinder lens 155 and projected on the surface of the photosensitive drum 158 as slit light. The scattered light 159 on the surface of the photoconductor drum 158 is condensed on the line sensor 151 via a reduction optical system, the output of the line sensor 151 is processed by the signal processing device 160, and then the defect is judged by the judgment processing device. Is.

FIG. 16 is a conventional automatic inspection device for the surface of a cylindrical body.
FIG. 17 is an explanatory view of a fifth example of FIG.
72 is a scanner, 173 is a light receiver, 174 is laser light, 1
75 is reflected light. This automatic inspection device is a scanner 17
Flying laser light 174 from the laser source prepared for 2
Sensing linearly polarized light at Brewster's angle in spot method
The reflected light 1 is incident on the inspection surface of the optical drum 171 and projected.
Two light receiving parts 173a provided with the light receiving device 173
Waviness composed of gentle unevenness by receiving light at 73b
This makes it possible to detect defects and minute irregularities. Well
Also, as shown in FIG. 17, the photosensitive layer of the photosensitive drum 171
Is a two-layer reflective layer L₁, L₂Consists of each reflected light
R ₁, R₂Laser light 174
Insert the 1/2 wave plate 1722 into
As described above, the laser light incident on the photosensitive drum 171 is P
It becomes polarized light and the reflected light R₁Becomes 0, and the reflected light R₂only
Is incident on the light receiver 173, so the above interference does not occur.
(JP-A-3-291552, etc.).

FIG. 19 is an explanatory view of a sixth example of a conventional automatic inspection device for the surface of a cylindrical body, in which 191 is a photosensitive drum and 1
Reference numeral 92 denotes a slit light source including a fluorescent lamp 1921 and a slit 1922, 193 denotes a light receiver including a line sensor, and 19
Reference numeral 4 is a projected light image, 195 is a central portion of the projected light image, 196 is a boundary portion of the projected light image, 197 is an image processing portion, and 198 is a defect determination portion.

As shown in the figure, in this conventional example, a white scattering light source forming a slit light source 192 is used as a light source,
The projected light image 1 on the surface of the photosensitive drum 191 which is the inspection object
The central portion 195 and the boundary portion 196 of 94 are received by the light receiver 193 including a line sensor, and the received light signal is received by the image processing unit 19
7 and the defect determination unit 198 determines the defect, which was previously filed by the present inventors (Japanese Patent Application No. 3-2714787).

[0017]

Among the above-mentioned conventional techniques, the first to fifth examples detect the strong scattered light Rm due to the mechanical flaw 31 described with reference to FIG. That is, in the first example, interference light is generated by the reflected light on the surface of the charge transport layer 21 which is the outermost surface of the photosensitive layer and the reflected light on the boundary surface of the charge generation layer 22 below the photosensitive layer. The interference fringe waveform is superimposed on the signal waveform received by the photomultiplier tube, and it has been difficult to extract a defect signal that emits weak scattered light Rc such as a coating defect.

When the influence of the interference fringes is eliminated by using the technique described in the second example, the object to be inspected is limited to the mechanical scratch on the surface of the photoconductor, and the lower photoconductor layer 22 (charge generation layer). It was difficult to detect the coating defect 32. Since the inspection method of the third example uses the same-magnification imaging element for the sensor array, there is a problem that the sensor array and the imaging element need to have a size larger than the width of the inspection drum, and the apparatus becomes large.

Further, in the method of detecting the surface defect by receiving the scattered light of the fourth example, the mechanical flaw 31 in which the surface metal is completely peeled off and the surface of the base metal such as aluminum is exposed. The mechanical flaw is generated by the slit light projected by the optical fiber bundle of halogen light to generate strong scattered light Rm, which is received by the line sensor at a position displaced by 10 to 20 degrees with respect to the angle of the regular reflection direction. However, since the thickness of each layer is about 0.1 μm to several tens of μm in the photoconductor coated in multiple layers, defects 34 such as “bulges” and “dents” due to subtle changes in film thickness are caused by optical fiber bundles. Almost no scattered light is generated for slit light. For this reason, it is impossible for the line sensor to detect defects such as "dents" at the light receiving position deviated from the regular reflection light direction by 10 to 20 degrees.

In the method of the fifth example, it is possible to detect the smooth unevenness 34 of the surface layer of the photoconductor while suppressing the interference phenomenon, but it is not possible to simultaneously detect the coating defect 32 of the lower layer,
Further, since the apparatus is a flying spot type, the size of the apparatus is large, and a dark room environment is required. On the other hand, the method of the sixth example is effective for detecting coating defects, and in experiments by the present inventors, the line sensor is focused on the center of the light image projected from the white scattering light source on the photosensitive drum to receive specular reflection light. By the method, "foreign matter", "bulge", and "axis line" are detected. Also, by the scattered light receiving method that focuses on the boundary part of the light image, "dents" and "sags" are received. "Stain" depending on the light receiving method
We were able to detect "patterns" and "mura". However, "dents" and "bulges" 34 have a depth and height of about 5 μm,
The detection of the surface inclination up to 1/300 was the limit.

The "dent" or "bulge" defect is a very gradual change in film thickness of the photosensitive layer of about several .mu.m when the difference in height is the smallest. Since the surface potential of the photoconductor is proportional to the film thickness of the photosensitive layer, the surface potential changes by several% at the above-mentioned "dimple" or "bulge" defect of the height difference. Changes by about 50 V, resulting in uneven lightness and unevenness in image quality.

In view of the problems of the prior art as described above, the present invention provides a surface of a substrate such as a metal uniformly coated with a coating, especially a surface layer of several μm of a photoreceptor layer coated in multiple layers. It is an object of the present invention to provide an optical photoreceptor defect inspection apparatus that receives a defect signal that can be discriminated by a threshold value using a line sensor for a defect caused by a gentle "dent" or "bulge".

[0023]

In order to achieve the above object, the first aspect of the present invention is to form a projected light image on the surface 2 of a cylindrical body 1 having an edge perpendicular to the axial direction thereof. A boundary portion 8 of the formed projection light image in the axial direction of the cylindrical body
The surface defect of the cylindrical body 1 is detected by detecting the change in.

The second aspect of the present invention is the surface 2 of the cylindrical body 1.
A band-shaped projected light image 6 having a long axis orthogonal to the axial direction of the cylindrical body 1 is formed along the axial direction of the cylindrical body 1. The surface defect of the cylindrical body 1 is continuously detected in the axial direction by detecting the change in the boundary portion in the axial direction.

In the third aspect of the present invention, the cylindrical body 1 is rotated, and a band-shaped projected light image 6 having a long axis orthogonal to the axial direction of the cylindrical body 1 is formed on the surface 2 of the cylindrical body 1. The band-shaped projection light image 6 formed by moving along the axial direction
The surface defect of the entire surface of the cylindrical body 1 is detected by continuously detecting the change in the axial center boundary portion 8 of the cylindrical body 1 in the axial direction of the cylindrical body 1.

The fourth aspect of the present invention is the surface 2 of the cylindrical body 1.
In a surface defect detecting device for irradiating the surface of the cylindrical body 1 with light and irradiating the surface of the cylindrical body 1 with a long axis perpendicular to the axial direction of the cylindrical body 1, the surface defect of the cylindrical body 1 is detected. The projector 4 that forms a strip-shaped projected light image 6 and the strip-shaped projection by aligning the longitudinal direction of the light-receiving visual field 7 with a boundary portion 8 of the strip-shaped projected light image 6 that is orthogonal to the axial center direction of the cylindrical body 1. A light receiver 5 for detecting reflected light in the vicinity of the boundary portion 8 in the axial direction of the light image 6, and detecting a surface defect of the cylindrical body 1 in the vicinity of the boundary portion in the axial direction.

The fifth aspect of the present invention is the surface 2 of the cylindrical body 1.
In a surface defect detecting device for irradiating the surface of the cylindrical body 1 with light and irradiating the surface of the cylindrical body 1 with a long axis perpendicular to the axial direction of the cylindrical body 1, the surface defect of the cylindrical body 1 is detected. The projector 4 that forms a strip-shaped projected light image 6 and the strip-shaped projection by aligning the longitudinal direction of the light-receiving visual field 7 with a boundary portion 8 of the strip-shaped projected light image 6 that is orthogonal to the axial center direction of the cylindrical body 1. A light receiver 5 for detecting reflected light in the vicinity of the axial boundary portion 8 of the light image 6, and a synchronous movement unit for synchronously moving the light projector 4 and the light receiver 5 along the axial direction of the cylindrical body 1. 10 is provided, and surface defects of the cylindrical body 1 are continuously detected in the axial direction in the vicinity of the axial boundary portion 8.

The sixth aspect of the present invention is the cylindrical body 1.
In the surface defect detection device for irradiating the surface 2 of the cylinder with light and detecting the change in the reflected light to detect the surface defect of the cylindrical body 1, the surface 2 of the cylindrical body 1 has a length perpendicular to its axial direction. A projector 4 for forming a belt-shaped projected light image 6 having an axis;
Reflection in the vicinity of the axial boundary portion 8 of the strip-shaped projected light image 6 by aligning the longitudinal direction of the light-receiving visual field with the boundary portion 8 of the strip-shaped projected light image 6 orthogonal to the axial center direction of the cylindrical body 1. Light receiver 5 for detecting light, the light projector 4 and the light receiver 5
The synchronous moving part 10 for synchronously moving the and along the axial direction of the cylindrical body 1, the cylindrical body rotating part 11 for rotating the cylindrical body 1, and the light receiving signal of the light receiving part 5 from the surface of the rotating body 1. Defect signal extraction unit 13 for extracting the surface defect signal of No. 2
And a defect determination processing unit 14 that determines the quality of the defect and the type of defect from the surface defect signal extracted by the defect signal extraction unit 13, and detects the surface defect of the cylindrical body 1 of the cylindrical body 1. The feature is that detection is performed continuously over the entire surface.

The cylindrical body which is the object to be inspected is, for example, a photosensitive drum, the projector is composed of a slit-shaped white diffused light source such as a straight tube fluorescent lamp light source, and the light receiver is composed of a line sensor. It is preferable to include a sensor attitude adjusting mechanism for matching a strip-shaped projected light image formed by projection of slit light formed on the surface of the inspection object with the light-receiving visual field of the line sensor, and a light receiver including the line sensor. The synchronous movement mechanism section that moves the projector in synchronization with each other is configured to be controlled in correlation with the rotation of the rotating body, so that, for example, a belt-shaped projected light image is formed on the surface of the cylindrical body by the belt-shaped projected light image. By continuously scanning in the axial direction and stepwise scanning in the circumferential direction with the band width, it is possible to continuously and automatically inspect the entire surface of the cylindrical body.

Further, although it is preferable that the defect judgment processing section is composed of a defect quality judgment processing section and a defect type judgment processing section, a known image processing apparatus may be used together with the defect signal extraction section. is there. Incidentally, the present invention, as the inspection object,
The present invention is not limited to the above-mentioned photoconductor drum, but can be a cylindrical body having a mirror surface and a curved surface, or a shape conforming to this.

[0031]

In the structure of the first aspect of the invention, the change in the axial edge of the cylindrical body 1 of the projected light image 6 formed on the surface 2 of the cylindrical body 1 and having the edge orthogonal to the axial direction thereof. Is detected, the surface defect of the cylindrical body 1 is detected. In the configuration of the second invention, the surface 2 of the cylindrical body 1
A band-shaped projected light image 6 having a long axis orthogonal to the axial direction of the cylindrical body 1 is formed along the axial direction of the cylindrical body 1. A change in the axial edge region is detected as a defect in the axial edge region of the cylindrical body surface in the axial edge region.

In the structure of the third invention, the cylindrical body 1
Is rotated, a strip-shaped projected light image 6 having a long axis orthogonal to the axial direction of the cylindrical body 1 is formed on the surface 2 by movement along the axial direction of the cylindrical body 1, and the formed strip-shaped image is formed. Of the projected light image 6 is detected in the axial edge region of the cylindrical body 1, and defects in the edge region of the cylindrical body surface are continuously detected in the axial edge region.

In the configuration of the above-mentioned fourth invention, the projector 4
Forms a band-shaped projected light image 6 having a long axis orthogonal to the axial direction on the surface 2 of the cylindrical body 1. The light receiver 5 is arranged orthogonal to the axial direction of the cylindrical body 1 and detects reflected light in the vicinity of the axial edge of the strip-shaped projected light image 6 formed on the surface 2 of the cylindrical body 1. . In the structure of the fifth aspect of the invention, the projector 4 forms a band-shaped projected light image 6 having a major axis orthogonal to the axial direction on the surface 2 of the cylindrical body 1.
The light receiver 5 is arranged orthogonal to the axial direction of the cylindrical body 1 and detects reflected light in the vicinity of the axial edge of the strip-shaped projected light image 6 formed on the surface 2 of the cylindrical body 1. . Also,
The synchronous moving unit 10 synchronously moves the light projector 4 and the light receiver 5 in the axial direction of the cylindrical body 1. As a result, the strip-shaped projected light image 6 is continuously moved in the axial direction of the cylindrical body 1, and a change in the edge region of the moving projected light image 6 is continuously detected along the axial direction of the cylindrical body. To be done.

Then, in the configuration of the sixth invention,
The light projector 4 projects a band-shaped projected light image 6 having a long axis orthogonal to the axial direction on the surface 2 of the cylindrical body 1. The light receiver 5 is arranged orthogonal to the axial direction of the cylindrical body 1 and detects reflected light near the edge in the axial direction of the strip-shaped projected light image 6 projected on the surface 2 of the cylindrical body 1. . The light projector 4
And the light receiver 5 are synchronously moved in the axial direction of the cylindrical body 1 by the synchronous moving unit 10 to move the projected light image 6
The change in the edge region of the cylinder is continuously detected along the axial direction of the cylindrical body. Then, the cylindrical body rotating unit 11 rotates the cylindrical body 1 and scans the entire surface of the cylindrical body with the projected light image. The output signal of the light receiver 5 is processed by the defect signal extraction unit 13, and the surface defect signal of the surface 2 of the rotating body 1 is extracted. The defect determination processing unit 14 determines the quality of the defect and the type of the defect from the surface defect signal extracted by the defect signal extraction unit 13. As a result, surface defects on the entire surface of the cylindrical body are detected.

In the above, the projector is composed of a band-shaped white scattering light source, and the band-shaped white scattering light source emitted from the light source is irradiated so as to have a long axis in the circumferential direction of the surface of the photosensitive drum. If there is a gradual dent or bulge defect on the surface of the projected light image projected and formed in the circumferential direction of the surface, the projected light is scattered by this defect and the edge portion in the longitudinal direction of the drum of the strip-shaped projected light image is scattered. Change. The line sensor in which the long axis of the visual field is arranged along the edge portion of the projected light image in the longitudinal direction of the striped light image and the focus is on the edge portion is the edge portion of the projected light image. Is received and a defect signal corresponding to the presence of a defect is output. The output signal of the line sensor is processed by the defect signal extraction unit, and the signal of the extracted defective portion is subjected to the non-defective / defective product determination process based on the feature of the signal and its feature amount in the defect determination processing unit according to its degree. , A discrimination signal is output for each type of defect.

[0036]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic view for explaining an embodiment of an apparatus configuration to which a surface defect inspection method according to the present invention is applied, in which 1 is a cylindrical body as an inspection object, 2 is a surface of the inspection object, 3 is a defect, Reference numeral 4 is a light projector, 5 is a light receiver, 6 is a projected light image, 7 is a field of view of the light receiver, and 8 is a boundary portion of the projected light image.

In the figure, the projector 4 forms a band-shaped projected light image 6 on the surface 2 of the cylindrical body 1 orthogonal to the axial direction of the cylindrical body 1. A light receiver 5 having a boundary portion 8 of the projected light image 6 as a visual field 7 is arranged to receive reflected light near the boundary portion 8 in the visual field 7. When there is a defect 3 on the surface 2 of the cylindrical body 1, the defect 3 causes distortion in the edge portion of the projected light image of the boundary portion 8, and this causes the light receiver 5 to distort.
Appear in the output of.

Therefore, the surface defect can be detected by analyzing the signal corresponding to the distortion. FIG. 2 is a schematic diagram for explaining another embodiment of the apparatus configuration to which the surface defect inspection method according to the present invention is applied. The same reference numerals as those in FIG. 1 correspond to the same portions, 11 is a cylindrical driving portion, 41 Is a fluorescent lamp,
42 is a slit, 51 is a line sensor, 52 is a reduction optical system, 10 is a synchronous moving unit, 12 is a three-axis attitude adjustment device, 13
Is a defect signal extraction unit, and 14 is a defect determination processing unit.

In this embodiment, a fluorescent lamp 41 is used as a light source forming the floodlight 4, and a slit 42 is provided on the front surface of the fluorescent lamp 41 along the longitudinal direction of the fluorescent lamp 41.
On the inspection surface 2 of the photoconductor drum, the major axis thereof is installed in the direction orthogonal to the axial direction of the cylindrical body 1 to form a strip-shaped projected light image 6. The fluorescent lamp 41 as a light source,
The diffused light source was selected because the illuminance of the diffused surface is high and the uniformity of the light amount distribution is good. According to the experiments by the present inventors,
As an optical positional relationship between the projector 4 and the cylindrical body 1,
The distance from the slit 42 to the inspection surface 3 is about 100 m
m, width of slit light is about 30 mm, diameter 84 mmφ
It is preferable to obtain a slit light image (projection light image) of about 10 mm on the surface 2 of the cylindrical body 1 by visual observation.

A slit 42 installed on the fluorescent lamp 41
And the line sensor 51 constituting the light receiver 5 are moved and scanned in the axial direction (longitudinal direction) of the cylindrical body 1 in synchronization with the cylindrical body 1 by the synchronous movement unit 10. When the scanning along the axial direction of the cylindrical body is completed, the cylindrical body (photosensitive drum in this case) 1 which is the surface inspection body is driven by the drive unit 11 at a constant angle (corresponding to the width in the longitudinal direction of the belt-shaped projected light image). Rotate only). The entire area of the surface 2 of the cylindrical body 1 is scanned by alternately and sequentially performing longitudinal scanning of the cylindrical body 1 and rotational scanning of the cylindrical body 1.

Since the surface of the photosensitive drum as the cylindrical body 1 is a mirror surface on which the photosensitive member is uniformly applied, the slit 42
Is projected onto the surface of the photosensitive drum to form a band-shaped projected light image 6. The line sensor 51 having a visual field aligned with the boundary portion 8 of the band-shaped projected light image 6 receives reflected light near the boundary line (near the boundary portion) of the boundary portion 8 of the projected light image 6 through the reduction optical system 52.

The light receiving field 9 of the line sensor 51 is set by the three-axis attitude adjusting device 52 so as to coincide with the boundary portion 8. That is, the direction of the light receiving field 9 is aligned with the circumferential direction of the photoconductor, and when the boundary portion 8 of the projected light image 6 scans the surface in the vicinity of the dent or bulge defect 3, the boundary line portion of the projected light image 6 concerned. The (edge portion) is disturbed, and the scattered light is received in the light receiving field 9. The line sensor 51 photoelectrically converts the reflected light in the vicinity of the boundary portion, supplies the output signal to the defect signal extraction circuit 13 to extract the defect signal, and the defect determination processing unit 14 determines whether the defect is good or not and the defect type determination device determines. Done.

FIG. 3 is a schematic view of the optical system of the above-described embodiment of the apparatus configuration to which the surface defect inspection method according to the present invention is applied, as seen from the cross-sectional direction of the photosensitive drum as a cylindrical body to be inspected. The same reference numerals as those in FIG. 2 correspond to the same parts.
In the figure, the light of the fluorescent lamp 41 passing through the slit 42 forms a projected light image 6 on the surface of the photosensitive drum (cylindrical body 1). The line sensor 51 is arranged with its major axis aligned in the circumferential direction of the photosensitive drum.

The range 61 in the circumferential direction of the photosensitive drum in which the line sensor 51 can receive the projected light image 6 is due to the interference of the arrangement of the fluorescent lamp 41 and the line sensor 51 in the photosensitive drum having a diameter of 84 mmφ. It was about 35 degrees. The surface defects mainly targeted by the present invention are subtle “dents” and “bulges” on the surface generated in the outermost charge transport layer of the drum composed of a plurality of organic photosensitive layers.

According to the conventional inspection by visual observation, as shown in FIG.
As shown in, when the drum position is set so that the "dent" and "bulge" defects are aligned with the boundary line (near the boundary) of the projected light, weak scattering due to surface irregularities on the boundary line is generated. There is a difference in the scattered light between the light and the part deviated from the boundary part to the outside, and the boundary line of the slit light image, which is originally a straight line, appears as an irregular line.

FIG. 4 is a schematic cross-sectional view of the main part of the cylindrical body in the circumferential direction for explaining the surface defect. In order to quantitatively show the "dent" or "bulge" defect, as shown in FIG. It is represented by a slope 341 using the radius-depth ratio of 34,
The inclination due to the curvature of the photosensitive drum in the circumferential direction is indicated by 342. In the figure, for a "dent" or "bulge" of about 1/300 in inclination, the light of the fluorescent lamp 41 passing through the slit 42 is projected in the longitudinal direction of the photosensitive drum (cylindrical body 1). It could be detected by observing the boundary in the circumferential direction. However, a very gentle “dent” having a depth of several μm and an inclination of about 1/1000 cannot be observed by the above method.

As shown in FIG. 4, the inclination 342 due to the curvature in the circumferential direction of the photosensitive drum is larger than the inclination 341 on the surface due to the "dent" defect, and the distribution of scattered light in the circumferential direction depends on the curvature. This is because the influence becomes dominant and the scattered light 61 due to the “dent” cannot be detected. As a result of observation and investigation, by projecting the projected light image in the circumferential direction of the photoconductor drum and observing the boundary region in the longitudinal direction of the photoconductor drum with no curvature, very gentle “dents” and “bulges”
It turns out that can be detected.

FIG. 5 is a schematic cross-sectional view of the main part of the cylindrical body in the axial direction for explaining the surface defect, and the same reference numerals as those in the above figures correspond to the same parts. The "dent" or "bulge" in the longitudinal direction (axial direction) of the photosensitive drum having no curvature is also detected by receiving the scattered light 61 from that portion.
FIG. 6 is a schematic view for explaining still another embodiment of the apparatus configuration to which the surface defect inspection method according to the present invention is applied, and is an apparatus configuration for shortening the scanning time of the entire surface of the cylindrical body (photosensitive drum). .

In the figure, the same reference numerals as those in the respective figures of the above-mentioned embodiment correspond to the same portions, 40 is a projector having a planar light source, 401 is a light shielding plate, 421 is a slit-shaped opening, and 50 is a slit.
Reference numerals 1 and 502 are light receivers. A plurality of light receivers 5 are provided for the projector 40 having a planar light source composed of a fluorescent light source or the like.
01 and 502 are arranged. The surface light source 40 is provided with a light shielding plate 401 having a slit-shaped opening 421 having a longitudinal direction in a direction orthogonal to the axial direction of the photoconductor 1 on the entire surface.

With this structure, there is provided a synchronous moving means for synchronously moving the slit-shaped opening 421 and the plurality of light receivers 501 and 502 having the line sensor 51 in the directions of arrows B and C, and the photosensitive drum is indicated by an arrow. The entire surface of the photosensitive drum is scanned by providing a driving means for driving in the A direction. With this configuration, it becomes easy to carry in and out the photosensitive drum as a cylindrical body that is a surface inspection body in the automation line. In addition, in this embodiment, the light projector 40 having a planar light source is used, so that the light projection angle and the light reception can be achieved. Since it is easy to set or change the optical conditions such as the angle, it is preferable that the photosensitive drum is installed in the longitudinal direction and the lower end portion of the photosensitive drum is held and rotated.

FIG. 7 is an explanatory view of the signal output of the line sensor which constitutes the photodetector, where 71 is the signal output (dark current level) of the line sensor on the normal surface, and 72 is the signal of the line sensor at the defective portion. Output, 73 is a threshold for discrimination,
The horizontal axis shows the pixel position of the line sensor, and the vertical axis shows the signal output of the line sensor. In the figure, the signal on the normal surface having no defect is almost the dark current level 71, and the signal 72 from the defective portion appears in the positive direction. This is discriminated by the threshold value 73 and the defect signal is extracted.

The accuracy of adjusting the projected light image receiving position of the line sensor may be about 10 times as high as the resolution of the line sensor on the surface to be inspected. When the light is received twice as much, it is about 0.01 degree.
This can be realized by the axis attitude adjusting device 12. For this attitude adjustment, it is preferable to adopt the three-axis attitude adjusting mechanism proposed in Japanese Utility Model Application No. 4-64763 filed by the present applicant for the purpose of reducing the adjustment man-hour, and as shown in FIG. 5
This is embodied by automatic posture adjustment around the longitudinal axis Z of 1, the axis X for receiving the light beam of the line sensor, and the lateral axis Y. Particularly, the field of view 9 is adjusted so as to match the boundary portion 8 of the projected light image 6 by the rotation about the axis X.

In the above embodiment, the straight tube fluorescent lamp is used as the light source forming the floodlight.
The configuration is not limited to this, and the following configuration may be adopted. FIG. 8 is a schematic view for explaining still another embodiment of the apparatus configuration to which the surface defect inspection method according to the present invention is applied.
Reference numerals a and 81b are halogen light sources, reference numerals 82a and 82b are optical fiber bundles, reference numeral 84 is a lens holder, reference numeral 85 is a perfect diffusing surface lens, and the same reference numerals as those in the above embodiment correspond to the same portions.

As shown in the figure, the light from the halogen light sources 81a and 81b constituting the projector 4 is made into slit light by the optical fiber bundles 82a and 82b, and the surface is scattered on the front surface of the end faces of the optical fiber bundles 82a and 82b. It is possible to add a perfect diffusing surface lens 85 such as a treated cylinder lens so as to emit white scattered light.

Also in this embodiment, the same effect as that of each of the above embodiments can be obtained. The object to be inspected is not limited to the light-transmissive photoreceptor applied on the mirror-finished metal drum in the above-described embodiment,
Even if it is a photoconductor drum with a roughened metal drum substrate for a laser printer, or a surface layer applied to a cylindrical substrate as well as the photoconductor drum, the surface layer is transparent. Even in the case of a non-coated film, since the applied surface layer is uniform and has a mirror-like surface, it is effective for detecting a very gentle dent defect as in each of the above examples.

[0056]

As described above, according to the present invention, based on the conventional inspection method of visual detection, the slit light of the white scattered light is applied to the surface of the cylindrical body such as the photosensitive drum as the inspection object. Is irradiated in the circumferential direction of the cylindrical body, and the vicinity of the boundary line portion in the longitudinal direction of the cylindrical body of the projection light image formed on the surface of the cylindrical body is set as the light receiving position of the line sensor that constitutes the light receiver. This makes it easy to detect very gentle “dents” and “bulges” defects.

Further, the inspection device can be downsized by using a reduction optical system for the light receiver, and by using white scattered light having a wide spectral distribution such as a fluorescent lamp for the light source, the laser light is projected. It is possible to easily extract the surface defect position while avoiding the occurrence of interference fringes in the conventional method of detecting by
It is possible to provide a surface defect inspection method and a device therefor which can easily extract a defect signal.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating one embodiment of an apparatus configuration to which a surface defect inspection method according to the present invention is applied.

FIG. 2 is a schematic diagram illustrating another embodiment of the apparatus configuration to which the surface defect inspection method according to the present invention is applied.

FIG. 3 is a schematic view of the optical system of the above-described embodiment of the apparatus configuration to which the surface defect inspection method according to the present invention is applied, as seen from the cross-sectional direction of a photosensitive drum as a cylindrical body that is an inspection object.

FIG. 4 is a schematic sectional view of an essential part for explaining a surface defect.

FIG. 5 is a schematic cross-sectional view of a main part in the axial direction of a cylindrical body for explaining a surface defect.

FIG. 6 is a schematic view for explaining still another embodiment of the apparatus configuration to which the surface defect inspection method according to the present invention is applied.

FIG. 7 is an explanatory diagram of a signal output of a line sensor which constitutes a light receiver.

FIG. 8 is a schematic diagram illustrating still another embodiment of the apparatus configuration to which the surface defect inspection method according to the present invention is applied.

FIG. 9 is a cross-sectional view of a main part of a photosensitive drum for explaining various defects that occur on the surface of the photosensitive drum.

FIG. 10 is an explanatory diagram of various defects that occur on the surface of the photosensitive drum.

FIG. 11 is an explanatory diagram of a first example of a conventional automatic inspection device for the surface of a photosensitive drum.

FIG. 12 is an explanatory diagram of a second example of a conventional automatic inspection device for the surface of a cylindrical body.

13 is an explanatory diagram of a wavelength region of a laser used in the conventional example of FIG.

FIG. 14 is an explanatory diagram of a third example of a conventional automatic inspection device for the surface of a cylindrical body.

FIG. 15 is an explanatory diagram of a fourth example of the conventional automatic inspection device for the surface of a cylindrical body.

FIG. 16 is an explanatory diagram of a fifth example of the conventional automatic inspection device for the surface of a cylindrical body.

FIG. 17 is a configuration diagram illustrating a countermeasure in the case where reflected light from a photosensitive layer of a photosensitive drum including two reflective layers interferes with each other.

FIG. 18 is an explanatory diagram of a light receiving state when reflected light from a photosensitive layer of a photosensitive drum including two reflective layers interferes with each other.

FIG. 19 is an explanatory diagram of a sixth example of a conventional automatic inspection device for the surface of a cylindrical body.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ...- Cylindrical body to be inspected, 2 ... Surface of inspected body, 3 ...- Surface defect, 4 ...- Projector, 41
.... Fluorescent lamp, 42 ... Slit, 5 ... Light receiver, 51 ... Line sensor, 52 ... Reduction optical system, 6 ... Projected light image, 7 ... ... View of receiver,
8 ... ・ Boundary portion of projected light image, 11 ... Cylindrical drive unit, 10 ... Synchronous moving unit, 12 ... Triaxial posture adjusting device, 13 ... Defect signal Extraction unit, 14 ...
・ Defect determination processing unit

Claims (6)

[Claims] 1. A projection light image having an edge perpendicular to the axial direction of the cylinder is formed on a surface of the cylinder, and a change in the formed projection light image at a boundary portion in the axial direction of the cylinder is detected. The surface defect inspection method is characterized by detecting the surface defect of the cylindrical body. 2. A strip-shaped projected light image having a long axis orthogonal to the axial direction of the cylindrical body is formed along the axial direction of the cylindrical body by movement, and the formed projected optical image of the strip shape is formed. The surface defect inspection method is characterized in that the surface defect of the cylindrical body is continuously detected in the axial direction by detecting a change in a boundary portion of the cylindrical body in the axial direction. 3. A cylindrical body is rotated, and a band-shaped projected light image having a long axis orthogonal to the axial direction of the cylindrical body is formed on the surface by moving along the axial direction of the cylindrical body. Characterized in that a surface defect on the entire surface of the cylindrical body is detected by continuously detecting a change in the axial direction boundary portion of the cylindrical body of the formed band-shaped projected light image in the axial center direction of the cylindrical body. Surface defect inspection method. 4. A surface defect detecting apparatus for irradiating a surface of a cylindrical body with light and detecting a change in reflected light thereof to detect a surface defect of the cylindrical body, wherein A projector for forming a belt-shaped projection light image having orthogonal long axes, and a projection part of the projection light image in which a longitudinal direction of a light receiving field is aligned with a boundary portion orthogonal to the axial center direction of the cylindrical body of the projection light image. A surface defect inspecting apparatus, comprising: a photodetector that detects reflected light in the vicinity of a boundary portion in the axial direction, and detects a surface defect of the cylindrical body in the vicinity of the boundary portion in the axial direction. 5. A surface defect detecting device for irradiating light on the surface of a cylindrical body and detecting a change in reflected light thereof to detect a surface defect of the cylindrical body, comprising: A projector that forms a strip-shaped projected light image having orthogonal long axes, and the strip-shaped projection in which the longitudinal direction of the light-receiving visual field is aligned with a boundary portion of the strip-shaped projected light image that is orthogonal to the axial direction of the cylindrical body. A light receiver for detecting reflected light in the vicinity of a boundary portion of the optical image in the axial direction, and a synchronous movement unit for synchronously moving the light projector and the optical receiver along the axial direction of the cylindrical body, A surface defect inspecting apparatus, wherein surface defects of a cylindrical body are continuously detected in the axial direction in the vicinity of the boundary portion in the axial direction. 6. A surface defect detecting device for irradiating a surface of a cylindrical body with light and detecting a change in reflected light thereof to detect a surface defect of the cylindrical body, wherein the surface of the cylindrical body has an axial direction thereof. A projector that forms a strip-shaped projected light image having orthogonal long axes, and the strip-shaped projection in which the longitudinal direction of the light-receiving visual field is aligned with a boundary portion of the strip-shaped projected light image that is orthogonal to the axial direction of the cylindrical body. A light receiver for detecting reflected light in the vicinity of the axial center boundary portion of the optical image, a synchronous moving unit for synchronously moving the light projector and the light receiver along the axial direction of the cylindrical body, and the cylindrical body. A cylindrical rotating part for rotating, and a defect signal extracting part for extracting a surface defect signal of the surface of the rotating part from a light receiving signal of the light receiving part,
The defect signal extraction unit is provided with a defect determination processing unit that determines the quality of the defect and the type of defect from the surface defect signal extracted by the defect signal extraction unit, and the surface defects of the cylindrical body are continuously applied over the entire surface of the cylindrical body. A surface defect inspection device characterized by detecting.