JPH09196643A - Apparatus and method for inspection of appearance of photosensitive body of electrophotography - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an apparatus and a method in which a linear abnormality part and a large-area abnormality part with a small shading difference on the surface of a photosensitive body can be detected in a manner which is equivalent to visual inspection. SOLUTION: An apparatus is provided with a light source 2 which project light on the outer circumferential face of a cylindrical photosensitive body 1, with a line sensor 3 which scans an irradiation face, which receives reflected light and detects an optical intensity inside the face, with a signal processing part 4 which processes the output of the sensor and detects the abnormality of the appearance of the photosensitive body 1 and with a means which turns and drives the photosensitive body 1 around the axis. In this case, the signal processing part 4 stores the output of all pixels by the line sensor 3 which scans the whole surface of a photosensitive body 1, it performs image processing on the basis of the output of all the pixels, an appearance inspection apparatus which detects the abnormality of the appearance is formed, the whole surface of the photosensitive body 1 is scanned by the line sensor 3 by using the apparatus, the outputs of all the pixels are stored in the signal processing part 4, and the abnormality part of the appearance is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a visual inspection apparatus and an inspection method for an organic photoconductor for electrophotography, which is 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 become popular as electrophotographic photoconductors used in copying machines and printers to which electrophotographic technology is applied. The organic photoconductor 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. Furthermore, if necessary, an undercoat 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.

In such a photoreceptor, there are physical defects such as scratches on the surface of the support, contamination, chemical defects such as oxides, a photosensitive layer formed on the support, or undercoating. If defects such as scratches, coating unevenness, and mixture of foreign matters are present on the layer or the protective layer, the image processing function of the photoconductor is deteriorated, and defects occur in the obtained image. If the above-mentioned defects are present on the support or the photosensitive layer, the appearance of the surface of the photosensitive member becomes abnormal. In the photoconductor manufacturing line, the presence or absence of the above defects is inspected by a visual inspection in the final step.

Conventionally, as such an appearance inspection, a visual inspection has been performed by an inspector. However, since the visual inspection is a sensory inspection, a change in inspection level, erroneous judgment, oversight, etc. may occur to some extent. Inevitable, because of that,
The inspection level was high and the cost was high because it was necessary to prevent overlooking of defective products by tightening the inspection level and spending a lot of time in the inspection.

As a countermeasure against this, development of an automatic inspection device is in progress. As one of them, paying attention to the fact that the intensity of the reflected light is different between the normal part and the abnormal part of the surface of the photoconductor when illuminating the photoconductor surface and observing the reflected light. A method is known in which light is irradiated in a band shape along the axial direction, the reflected light is received by a line sensor that scans the surface of the photoconductor to detect the light intensity, and the output is processed to detect an abnormal appearance part. There is. According to this method, the entire surface of the photoconductor can be easily inspected by rotating the photoconductor once in the axial direction. A line sensor of a CCD camera is preferably used as a sensor for scanning the surface of the photoconductor.

The image defect appears as a portion having a darker density (dark portion) or a portion having a lighter density (lighter portion) than the normal portion of the image. When the photoconductor is irradiated with light, the abnormal portion on the surface of the photoconductor corresponding to the image defect with high density has less light reflection than the normal part, and the output (luminance level) of the CCD camera is low, resulting in the image defect with low density. There is more light reflection in the abnormal surface area of the photoconductor that corresponds to
The output of the camera is high. Therefore, the abnormal portion can be detected by swinging the output of the CCD camera higher or lower than the output of the normal surface portion of the photoconductor.

FIG. 2 shows an example of a photoconductor surface abnormal portion detection signal obtained by processing the output of a CCD camera with a conventional apparatus and method. In FIG. 2, the horizontal axis is the time axis, and the vertical axis is the signal obtained by processing the output of the pixel of the CCD camera when receiving the reflected light from the normal portion of the photosensitive member surface,
On the other hand, the fluctuation (amplitude) in the ± direction of the signal obtained by processing the output of each pixel of the CCD camera from each part of the photosensitive member surface is shown. The peaks 5 and 7 of the waveform swung in the + direction correspond to the image defects having a low density, and the peaks 6 and 8 of the waveform swung to the − direction correspond to the image defects of a high density. Since the abnormality is detected by the variation in the ± direction with respect to the reference value in this manner, the reference value matches the center value of the gradation of the brightness level of the CCD camera in order to detect both the dark and light abnormalities with high sensitivity. As described above, it is necessary to select the intensity of the light with which the surface of the photoconductor is irradiated. FIG. 2 shows the case of a CCD camera having a brightness level gradation of 250.
The irradiation light is selected so that 5 becomes the reference value. Also,
According to the actual measurement, some signal fluctuations are observed even in the normal area of the surface of the photoconductor, so in reality, when the detection level that is the threshold value in the ± direction with respect to the reference value is set and the level is exceeded, Will be determined to be abnormal. In FIG. 2, the case where this threshold value is 15 is shown by a broken line. Therefore, FIG.
Point-like peaks 9 and 11 and continuous peak 1 in
Since 0 and 12 do not exceed the threshold value, they are not detected as abnormal parts.

[0008]

The abnormal part includes a dot-like high density abnormal part, a low-density abnormal part, a linear high-density abnormal part, a low-density abnormal part and a relatively wide area density. There are dark areas and areas with low density. In the case of visual inspection, the inspector determines the lightness and darkness after grasping the overall density, so even if there is little difference in lightness and darkness between the dot-like abnormal part, the linear abnormal part, and the wide-area abnormal part, With regard to the abnormal part that causes the above problem, all can be detected as the abnormal part by referring to the limit sample. However, in the inspection device using the conventional CCD camera as described above, the memory is minimized and the quality is judged for each line of the line sensor. Therefore, a linear portion with a small difference in light and shade (a peak value does not exceed the threshold value) (for example, a fine scratch or the like) (in the detection signal, it appears as 9 in FIG. 2), a wide area (in the detection signal, 2) is not detected, but an image defect may occur from such a portion (for example, a portion having a large area with a diameter of several mm or more), which is regarded as normal. Therefore, image defects are generated, and the correlation with the visual inspection is not good.

The present invention solves the above problems and provides a visual inspection apparatus and an inspection method capable of detecting a linear abnormal portion having a small difference in light and shade and an abnormal portion having a large area in the same manner as visual inspection. To aim.

[0010]

According to the present invention, there is provided a light source for irradiating light on the outer peripheral surface of a cylindrical photosensitive member in the direction of the cylinder axis, and a reflected light is received by scanning the irradiation surface. A line sensor that detects in-plane light intensity, a signal processing unit that processes the output of the sensor to detect an abnormal appearance of the photoconductor, and a unit that rotationally drives the photoconductor about a cylindrical axis. In the appearance inspection apparatus for an electrophotographic photoreceptor, the signal processing unit stores the output of all the pixels of the line sensor that scans the entire surface of the photoreceptor, and the output of all the pixels is image-processed to cause an abnormal appearance. A visual inspection device for an electrophotographic photoconductor that detects a portion of the image, and using such a device, the entire surface of the photoconductor is scanned by a line sensor, and the output of all pixels is stored in a signal processing unit. Process output Calculating an average output of the total surface Te, it is solved by detecting the abnormality of the appearance of the average output and the difference image processing to the photosensitive member surface and the output of each pixel.

As described above, by performing image processing on the output of the pixels on the entire surface of the photosensitive member, it is possible to recognize a linear abnormal portion and an abnormal portion having a large area as an image, and the difference in gray scale is small, and the conventional method is used. It is possible to detect a linear portion or a portion having a large area (portions 10 and 12 in FIG. 2) which is difficult to detect by the device and the detecting method as the abnormal portion.

[0012]

1 is a plan view of the inspection apparatus and inspection method of the present invention, FIG. 1 (a) is a plan view, and FIG. 1 (b) is a side view. While rotating the cylindrical photoreceptor 1 having an outer diameter of bmm and a length of cmm about its cylindrical axis (a rotation mechanism is not shown), a light source 2 (for example, a fluorescent lamp) is provided on the surface of the photoreceptor 1 along the axial direction. To irradiate the light, and the reflected light is a CCD camera (line sensor) with a resolution of amm 3
Then, the output for each pixel is stored in the signal processing unit 4. After storing and accumulating the output of all the pixels when scanning the entire surface of the photoconductor with a line sensor, the average output of all the pixels is calculated, and the change in the output difference of each pixel is calculated and image processing is performed. Even if the output fluctuation is small, it is possible to detect an elongated linear abnormal area or an abnormal area over a wide area. The number of pixels A in the axial direction on the surface of the photoconductor is c / a,
Since the number of pixels B in the circumferential direction is 3.14 × b / a, a memory of A × B or more, that is, 3.14 × b × c / a ² or more is required to store all the outputs of these pixels. Will be needed. Therefore, the input memory of the signal processing unit of the inspection device is set to a memory larger than this, and image processing is performed based on the output of all these pixels, so that it is possible to detect a linear abnormal area or an abnormal area having a large area. Becomes

For example, using an inspection device using a CCD camera having a resolution of 0.048 mm, an outer diameter of 30 mm and a length of 24
If a visual inspection of a 0 mm photosensitive member is performed, the number of pixels A in the axial direction is 240 / 0.048 = 5,000 (pieces), and the number of pixels B in the circumferential direction is 3.14 × 30 / 0.048 =
1,963 (pieces), and by setting the input memory of the signal processing unit to A × B = 9,815,000 or more, all pixels are memorized, and the signal processing as described above becomes possible.

[0014]

According to the present invention, a light source for irradiating light on the outer peripheral surface of a cylindrical photosensitive member in the direction of the cylinder axis, and a reflected light is received by scanning the irradiation surface to detect the in-plane light intensity. Appearance inspection device for electrophotographic photoreceptor having a line sensor, a signal processing unit that processes an output of the sensor to detect an abnormality in the appearance of the photoreceptor, and a unit that rotationally drives the photoreceptor around a cylindrical axis. In the appearance inspection device, the signal processing unit stores the output of all pixels of the line sensor that scans the entire surface of the photoconductor, and performs image processing with the output of all pixels to detect an abnormal portion of the appearance. Using such a device, scan the entire surface of the photoconductor with a line sensor, store the output of all pixels in the signal processing unit, and calculate the average surface output of the entire surface of the photoconductor by the output of all pixels. , The difference between the average output of the output of each pixel image processing to detect an abnormality of the external appearance of the photoreceptor surface. By adopting such an apparatus and method, it is possible to improve the correlation with the visual inspection even for the linear abnormal area with a small difference in gray level and the abnormal area with a large area, which were difficult to detect with the conventional apparatus and method, and The error of the abnormal part detection from the inspection is
It can be significantly reduced from 50% in the method to 10% or less.

[Brief description of drawings]

1A and 1B are principle explanatory diagrams of an inspection apparatus and an inspection method according to the present invention, in which FIG. 1A is a plan view and FIG. 1B is a side view.

FIG. 2 is a waveform diagram of an example of an abnormal appearance portion detection signal in a conventional inspection apparatus and inspection method.

[Explanation of symbols]

1 Photoreceptor 2 Light Source 3 CCD Camera (Line Sensor) 4 Signal Processing Part 5 Dotted or Linear Abnormal Area with Low Concentration 6 Abnormal Area with Dotted or Linear Dark Concentration 7 Abnormal Area with Low Density 8 Abnormal area with high density over a wide area 9 Point or linear area with low density difference and low density 10 Wide area with low density difference and low density 11 Point or linear area with low density difference and low density 12 Wide area with little difference in density and high density

Claims (2)

[Claims] 1. A light source for irradiating light on the outer peripheral surface of a cylindrical photosensitive member in the cylindrical axis direction, a line sensor for detecting reflected light by scanning the irradiation surface and detecting the light intensity within the surface, and a line for the line sensor. In the appearance inspection apparatus for an electrophotographic photosensitive member, which includes a signal processing unit that processes an output of a sensor to detect an abnormal portion of the external appearance of the photosensitive member, and a unit that rotationally drives the photosensitive member around a cylindrical axis, An electrophotographic photosensitive member characterized in that the processing unit stores the output of all the pixels of the line sensor which scans the entire surface of the photosensitive member, and performs image processing with the output of all the pixels to detect an abnormal appearance portion. Appearance inspection device. 2. The appearance inspection apparatus for an electrophotographic photosensitive member according to claim 1, wherein the entire surface of the photosensitive member is scanned by a line sensor, the output of all pixels is stored in a signal processing unit, and the output of all pixels is output. A method for inspecting the appearance of an electrophotographic photosensitive member, characterized by detecting an abnormal appearance portion on the surface of the photosensitive member by image processing.