JPH0961362A - Defect inspecting device for electrophotographic photoreceptor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a defect inspecting device in which the defect of a photoreceptor, even when it is a defect with little density difference or shallow flaw, can be detected with high sensitivity regardless of the kind of the photoreceptor. SOLUTION: In the defect inspecting device having a light source 2 for emitting a light along the axial direction of the peripheral surface of a cylindrical photoreceptor 1, a CCD camera (surface scanning line sensor) 3 for scanning the emitted surface, thereby receiving the reflected light of the emitted surface to detect the intensity of light, and a rotating motor 5 for rotating the photoreceptor 1 around the cylindrical axis, a light source having a peak wavelength within a range longer than the color wavelength of the peripheral surface of the photoreceptor which is a body to be inspected by 50nm-170nm is used as the light source 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect inspection apparatus for an electrophotographic organic photoconductor used in a copying machine or a printer for electrophotographic application products.

[0002]

2. Description of the Related Art In recent years, organic photoconductors have rapidly become widespread as electrophotographic photoconductors used in electrophotographic application devices. Such an organic photoreceptor is usually manufactured by forming a photosensitive layer made of an organic material on the outer peripheral surface of a conductive cylindrical support by a coating method. Further, if necessary, a subbing layer may be provided between the support and the photosensitive layer or a protective layer may be provided on the surface of the photosensitive layer by a coating method.

In such a photoreceptor, there are physical defects such as scratches on the surface of the support, contamination, chemical defects such as oxides, and a photosensitive layer or an undercoat layer formed on the support. If there are defects such as scratches, coating unevenness, and the mixture of foreign matters on the protective layer and the like, the image processing function of the photoconductor is deteriorated, and defects occur in the obtained image. For this reason, in the final step of the photoconductor manufacturing line, the presence or absence of defects as described above is inspected by visual inspection. That is, when observing the reflected light by irradiating the outer peripheral surface of the photoconductor, the intensity of the reflected light is different between the normal part and the defective part of the photoconductor,
The outer peripheral surface of the photoconductor is irradiated with light and the reflected light is observed to inspect for defects.

As a defect inspection as described above, a visual inspection has been conventionally performed by an inspector. However, since the visual inspection is a sensory inspection, a change in inspection level, erroneous judgment, and oversight may occur to some extent. Inevitably, therefore, it is necessary to prevent the defective products from being mixed in with the good products by tightening the inspection level and taking sufficient time for the inspection, which is a risky and costly inspection. Met. In addition, the degree of eye fatigue of the inspector is high, which is a worrying method for health problems. Therefore, the introduction of a defect inspection method instead of visual inspection has been urgently needed.

As such a defect inspection method, various photoelectric automatic inspection methods such as a laser light source method, an optical fiber method, and a CCD camera method have been proposed. The laser light source method is effective for defects such as surface scratches that scatter light because the light source has a single wavelength, but its detection capability is weak for defects that have no unevenness on the surface and have a light and shade difference.
The optical fiber method, which sets the light irradiation and light receiving parts, can detect scratches and detect differences in light and shade, but the measurement area is a spot and the inspection takes time. The CCD camera system can detect both scratches and grayscales. The CCD camera system includes an area sensor and a line sensor. The area sensor is suitable for defect inspection of an inspection surface having a flat surface and a relatively small area, and the line sensor has an inspection surface having a flat surface and a large area. It is suitable for defect inspection of cylindrical products that can be rotated around the cylinder axis.

In the electrophotographic photosensitive member, a photosensitive layer or the like is usually formed on the outer peripheral surface of a cylindrical support, and as a defect inspection device for the photosensitive member, a CCD camera type line sensor device is suitable. Development is in progress. FIG. 1 is a diagram showing a configuration of an example of such a defect inspection apparatus.
1A is a side view, and FIG. 1B is a front view. A light source 2 (for example, a fluorescent lamp) that uniformly projects light in a strip shape along the axial direction on the outer peripheral surface of the cylindrical photoreceptor 1 is arranged,
When the angle α with the light source 2 as viewed from the cylindrical axis of the photoconductor 1 is within a range of 90 °, the focus is placed on the outer peripheral surface of the photoconductor 1 at the highest illuminance point where the direct light strikes the projection surface of the light source 2. CCD camera 3 as a scanning line sensor to match
Is arranged. A plurality of CCD cameras 3 are arranged so that the entire length can be inspected at one time according to the length of the photoconductor 1 (two cases are shown in the figure). Reference numeral 4 is a signal processing unit that receives the output of the CCD camera 3 and processes the signal, and reference numeral 5 is a drive motor that rotates the photoconductor 1 about its cylindrical axis. In the apparatus having such a structure, the light source 2 is connected to the photosensitive member 1
Light is irradiated in a band shape on the outer peripheral surface of the device along the axial direction, the reflected light is received by the CCD camera 3, the light intensity is detected, and the output is processed by the signal processing unit 4 to detect a defect. By rotating the photosensitive member 1 around the cylindrical axis by the drive motor 5, the entire peripheral surface of the photosensitive member is scanned and the entire surface of the photosensitive member can be easily inspected.

The image defect appears as a dark (dark) portion or a light (light) portion as compared with the density of a normal portion on the image. When a photoconductor is irradiated with light, a photoconductor defect (hereinafter referred to as a dark defect) that appears as a high density portion on an image
Has less light reflection than the normal part, and the output of the CCD camera is low. Further, a photoconductor defect (hereinafter referred to as a bright defect) that appears as a low density on the image has more light reflection than a normal portion, and the output of the CCD camera is high. Therefore,
The defect of the photoconductor can be detected by swinging the output of the CCD camera higher or lower than the output of the normal portion of the photoconductor.

In FIG. 2, in the device as described above, CC
An example of the defect detection signal from the signal processing unit obtained by processing the output of the D camera is shown. In FIG. 2, the horizontal axis is the time axis, and the vertical axis is the signal obtained by processing the output of the CCD camera when it receives the reflected light from the surface of the normal portion of the photoconductor as the reference value 0. The fluctuation (amplitude) in the (±) direction of the signal obtained by processing the output of the CCD camera when receiving the reflected light from each part of the surface is shown. (+) In the figure
Each peak point a, b of the waveform swayed in the direction is a bright defect,
The peak points c and d of the waveform swayed in the (-) direction correspond to dark defects, of which a and d indicate defects in a region where the difference in shade is large and small compared to the normal portion, and b and c are It shows a defect in a large area with a small difference in light and shade compared to the normal area. As described above, since the defects are detected by the variation in the (±) direction with respect to the reference value 0, it is important to detect both the dark and light defects with equal sensitivity. Further, according to the actual measurement, some signal fluctuation is observed even in a normal portion region where there is no defect on the surface of the photoconductor, and therefore, in reality, the judgment level ((±) direction threshold value with respect to the reference value 0 ( (Indicated by a broken line in the figure) is set, and if it swings more than that level, it is determined as a defect.

[0009]

By the way, as described above, an automatic inspection device of various ideas can be considered as an alternative to the visual inspection, but any of them requires enormous confirmation experiments. In addition, the photosensitive material and the sensitivity of the organic photoconductor are selected according to the performance of a copying machine or a printer to be mounted, and there are various types of photoconductors. CCDs are used as scanning sensors for various types of organic photoconductors.
As a result of performing a defect inspection by an automatic inspection device using a camera, there may be a problem in the detection ability of a defect that has a small density difference and is not clearly visible, or a shallow scratch, and that the detection ability of the defect varies depending on the type of the photoconductor. It turns out that there is a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems and to provide a defect inspection apparatus capable of sensitively detecting a defect having a small difference in density and a shallow defect regardless of the type of the photoconductor.

[0011]

According to the present invention, the above-mentioned problems can be solved by: a light source for irradiating light along the cylindrical axial direction of the outer peripheral surface of a cylindrical photoconductor; and an irradiation surface for scanning the irradiation surface. A surface scanning line sensor that receives reflected light and detects the light intensity, a signal processing unit that processes the output of the sensor and detects surface defects of the photoconductor, and the photoconductor is rotationally driven around a cylindrical axis. In the defect inspection apparatus for an electrophotographic photosensitive member, the peak wavelength of the light source is 50 n from the color wavelength of the outer peripheral surface of the photosensitive member as the inspection object.
It is solved by a defect inspection apparatus for an electrophotographic photosensitive member using a light source having a long range of m to 170 nm.

When the color wavelength of the outer peripheral surface of the photosensitive member is 500 nm to 520 nm, the peak wavelength of the light source is 57 nm.
It may be 0 nm to 670 nm. As described above, the photosensitive material is selected according to the performance of the copier or printer to be mounted, and the photosensitive material and sensitivity are selected.
The color wavelength on the surface of the photoconductor changes. By changing the wavelength of the light source that irradiates the surface of the photoconductor in accordance with the color wavelength of the surface of the photoconductor, the detectability of defects varies. The defect detection capability can be enhanced by using a light source having a peak wavelength longer by 50 nm to 170 nm than the color wavelength of the surface of the photoconductor.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The relationship between the wavelength of a light source and the defect detection capability was examined by using a defect inspection apparatus having a structure as shown in FIG. Surface color wavelength is 500nm-520nm
An output signal from the same defective portion was detected by changing the wavelength of the light source using a (green) photoconductor. The result is shown in FIG.
In FIG. 3, the vertical axis represents the peak value of the fluctuation (amplitude) of the signal from the defective portion in the (±) direction with the output signal from the normal portion as the reference value 0, and the horizontal axis represents the wavelength of the light source. As shown in FIG. 3, among the defects, the bright unevenness in which the output signal swings in the (+) direction has a larger peak value as the wavelength of the light source becomes longer than the color wavelength of the surface of the photoconductor and is easy to detect. Variation in peak value becomes large. Similarly, the peak value of the white spot becomes large and it becomes easy to detect, but 670 nm
It does not change above a certain level. The dark linear unevenness in which the output signal swings in the (-) direction has a peak value that increases as the wavelength of the light source increases in a range where the wavelength of the light source is 550 nm, which is approximately 50 nm longer than the color wavelength of the surface of the photoconductor.
When the wavelength of the light source is about 660 nm or more, the peak value tends to decrease.
For these defects, the peak wavelength is 570 nm to 6
It can be seen that high defect detection capability can be obtained by using a light source within the range of 70 nm, that is, within the range of 50 nm to 170 nm from the color temperature of the surface of the photoconductor. The highest detection ability is obtained when the color temperature is 650 nm to 660 nm.

While the three types of defects that generally occur frequently have been described above, almost the same results can be obtained for other defects. For other types of photoconductors having different surface color temperatures, the range of 50 nm to
By using a light source having a peak wavelength that is 170 nm longer, the defect detection capability is improved as described above.

[0015]

According to the present invention, a light source for irradiating light on the outer peripheral surface of a cylindrical photosensitive member along the cylindrical axis direction, and a light reflected by the irradiating surface are received by scanning the irradiating surface and the light intensity thereof is obtained. For an electrophotographic photosensitive member having a surface scanning sensor for detecting a signal, a signal processing unit for processing an output of the sensor to detect a surface defect of the photosensitive member, and a unit for rotationally driving the photosensitive member around a cylindrical axis. In the defect inspection apparatus, by using, as the light source, a light source having a peak wavelength in the range of 50 nm to 170 nm longer than the color wavelength of the outer peripheral surface of the photoconductor as the object to be inspected, defects and shallow scratches with little difference in density are sensitive. It can be detected well. Further, even when the color temperature of the surface of the photoconductor differs depending on the type of the photoconductor, it is possible to detect with equal sensitivity.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an example of a defect inspection apparatus according to the present invention, FIG. 1 (a) is a side view, and FIG. 1 (b) is a front view.

FIG. 2 is a waveform diagram of an example of a defect detection signal output from the defect inspection apparatus illustrated in FIG.

FIG. 3 is a diagram showing the relationship between the wavelength of the light source of the defect inspection apparatus and the defect detection capability.

[Explanation of symbols]

 1 photoconductor 2 light source 3 CCD camera 4 signal processing unit 5 drive motor

Claims (2)

[Claims] 1. A light source for irradiating light along a cylindrical axis of an outer peripheral surface of a cylindrical photoreceptor, and a surface scanning sensor for detecting reflected light of the irradiating surface by scanning the irradiating surface and detecting the light intensity thereof. In the defect inspection apparatus for an electrophotographic photoconductor, which comprises: a signal processing unit that processes an output of the sensor to detect a defect of the photoconductor; and a unit that rotationally drives the photoconductor around a cylindrical axis, As a defect inspection apparatus for an electrophotographic photosensitive member, a light source having a peak wavelength in the range of 50 nm to 170 nm longer than the color wavelength of the outer peripheral surface of the photosensitive member as the inspection object is used. 2. The electrophotographic apparatus according to claim 1, wherein the color wavelength of the outer peripheral surface of the photoconductor as the inspection object is 500 nm to 520 nm, and the peak wavelength of the light source of the inspection device is 570 nm to 670 nm. Defect inspection device for photoconductor.