JPH0755710A - Defect inspecting device for drum of photoreceptor - Google Patents

Abstract

PURPOSE:To provide a defect inspecting device for the drum of a photoreceptor, which can accurately detect many kinds of diversified defects including the defects on the surface of the drum and the defects in the inside of a photosensitive layer with excellent sensitivity. CONSTITUTION:This device comprises the combination of a light source 4, which emits the light in the axial direction of the surface of a photoreceptor drum 1, two stages of CCD cameras 5A and 5B as the line sensors, which are arranged on both sides of the light source 4 with the light source 4 in-between, receive the reflected light from the drum and the detect the intensity of the light, a signal processing part 6 thereof and a driving motor 7 for rotating the photoreceptor drum 1. The CCD camera 5A and 5B are focused on a bright part A, on which the direct emitted light is cast from the light source 4, and a dark part B, on which the scattered light is cast, on the surface of the photoreceptor drum 1. The drum 1 rotated under this state, and the light source 4 is turned ON. The defects such as the flaws formed in the surface of the photoreceptor drum 1, the foreign matters mixed into the inside of the photosensitive layer, the unevenness of painting of the photosensitive layer and the like are detected through the CCD camera 5A and 5B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic photoconductor (OP) used in a copying machine or a printer for electrophotography.
C) A drum surface defect inspection apparatus.

[0002]

2. Description of the Related Art First, the structure of the organic photoconductor drum described above and the state of defects occurring on the photoconductor drum are shown in FIG.
Shown in (a) and (b). In the figure, 1 is a photosensitive drum,
Reference numeral 2 denotes the drum tube 1, 3 is a photosensitive layer formed on the surface of the drum tube 1, and the photosensitive layer 3 is a carrier generation layer (CG).
Layer) 3a and carrier transport layer (CT layer) 3b.

By the way, in the manufacturing process, the photosensitive drum may have defects such as scratches on the surface and in the photosensitive layer, the mixture of foreign matters, or uneven coating. Image processing function deteriorates. In FIG. 6B, X is a surface defect such as a scratch,
Y represents an internal defect such as foreign matter mixed in the photosensitive layer and uneven coating. Therefore, in the photoconductor drum manufacturing line, a defect inspection is performed in the final inspection step to check whether there is the above-mentioned surface defect or internal defect.

As the defect inspection method, at present, visual inspection is generally performed by an inspector. However, since this visual inspection has a limited inspection capability, various photoelectric methods that can replace visual inspection are used. An automatic inspection method has been proposed and its development is in progress. Further, as one of the defect inspection methods, an apparatus for inspecting a surface defect of a photoconductor drum by using a CCD camera as a line sensor is disclosed in JP-A-3-5443.
It is already known in Japanese Patent Publication No. 8 and the like.

FIG. 7 shows this defect inspection apparatus, in which 4 is a light source (for example, a fluorescent lamp), and 5 is a line C.
A CCD camera as a line sensor having a built-in CD element 5a and a condenser lens 5b, 6 is a signal processing unit (image processing circuit), 7 is a drive motor for rotating the photosensitive drum 1, and the CCD camera 5 is on the drum surface. Of the light source 4 is focused and arranged on the projected surface of the light source 4, in particular, at the point where the illuminance is the highest when the direct light strikes. When the light source 4 is turned on with such a configuration, the drum surface is irradiated with a band of light along the axial direction, and the reflected light is received by the CCD camera 5.
Further, if the photosensitive drum 1 is rotated once by the drive motor 7, the entire peripheral surface of the drum is scanned. Then, based on the output signal of the CCD camera 5, the signal processing unit 6 determines the presence / absence of a defect, the size of the defect, etc. and outputs a defect signal.

[0006]

By the way, the above-mentioned C
The defect inspection device employing the CD camera has the following drawbacks in terms of inspection capability. That is, when the light source 4 and the CCD camera 5 are arranged with respect to the photoconductor drum 1 in a positional relationship as shown in FIG. 7, most of the light rays emitted from the light source are transparent to the photosensitive layer 3. After passing through, it reaches the surface of the drum tube 2 and is reflected. For this reason, although the surface defect X or the internal Y shown in FIG. 6B can be detected as the light emission intensity of the light source is relatively deep, the surface defect having a relatively deep scratch and the internal defect having a clear shade are detected. The surface defects such as shallow scratches and the internal defects with a small difference in density are transmitted without being attenuated. Therefore, the light receiving amount of the CCD camera hardly shows a difference from the normal surface area having no defect. , Becomes undetectable. On the contrary, when the light intensity of the light source is low, the detection sensitivity is lowered, so that the shallow scratch on the drum surface can be detected, but the defect inside the photosensitive layer cannot be accurately detected.

The present invention has been made in view of the above points, and an object thereof is to solve the above problems and to detect a wide variety of defects including defects on the surface of a drum and defects inside the photosensitive layer with high sensitivity and accuracy. Another object of the present invention is to provide a defect inspection apparatus for a photosensitive drum.

[0008]

In order to achieve the above object, the defect inspection apparatus of the present invention receives a light source which irradiates light in the axial direction of the surface of the photosensitive drum and a light which is reflected from the irradiation surface. It is composed of a line sensor for detecting the light intensity, a signal processing unit for the line sensor, and a rotation driving means for the photoconductor drum, and scatters a bright part which is formed by the light source on the surface of the photoconductor drum. It is assumed that the line sensors are focused on the dark areas exposed to the light to detect defects.

Further, in the above structure, as a concrete means for detecting a defect by focusing the line sensor on the bright portion and the dark portion formed on the surface of the photosensitive drum, it is carried out in the following manner. You can (1) One light source is provided, and a two-stage line sensor is opposed to the circumference of the photoconductor drum by focusing on the bright and dark parts formed on the surface of the photoconductor drum by irradiation from the light source. Deploy.

(2) The line sensor is used as one stage, and two light sources for forming a bright portion and a dark portion are provided at the focus position of the line sensor, and the light sources are alternately turned on to detect a defect. (3) One stage of line sensor and one light source are arranged, and the light source is provided with a projection slit with a shutter for forming a bright portion and a dark portion at a focus position of the line sensor, and a shutter for each slit is provided. The defects are detected by alternately switching.

[0011]

As described above, the belt-shaped bright portion on which the direct light of the light source strikes and the dark portion on which the scattered light strikes are formed on the surface of the photosensitive drum, and the light portion and the dark portion are respectively focused by the line sensor. By detecting defects in combination with the above, surface defects such as deep scratches and defects inside the photosensitive layer are detected in the bright portion, and surface defects such as shallow scratches are detected in the dark portion. Then, the photosensitive drum is rotated to inspect the entire surface of the drum. As described above, by performing the defect detection of the photoconductor drum separately for the bright portion and the dark portion, it becomes possible to accurately detect all of various surface defects and internal defects.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. In the drawings of each embodiment, the same members corresponding to FIGS. 6 and 7 are designated by the same reference numerals. Embodiment 1 FIGS. 1 (a), 1 (b) and 2 show an embodiment corresponding to claim 2 of the present invention, which is on the peripheral surface of the photosensitive drum 1 (diameter 30 mmφ, length 300 mm). Is provided with a light source (a rod-shaped fluorescent lamp) 4 which is opposed to the drum shaft in parallel to the drum axis.
CD cameras 5A and 5B are arranged toward the drum peripheral surface. The CCD cameras 5A and 5B are, for example, 2048 Bi
As shown in FIG. 2, two drums having a length of t are arranged side by side in the axial direction of the photosensitive drum 1 so that the drum full length region having a length of 300 mm can be detected.

Here, the CCD cameras 5A and 5B are respectively positioned under the following conditions. That is, when the surface of the photoconductor drum 1 is irradiated with the light emitted from the light source 4, a bright portion A of high illuminance on which the direct light from the light source 4 strikes a narrow area on the line connecting the light source and the drum center, and this bright portion A low-illuminance dark portion B on which light rays scattered by the reflection cover 4a of the light source 4 impinge is formed in a strip shape on both sides of the sandwiched portion.
Therefore, the CCD camera 5A of one stage focuses on the P position in the bright portion A, and the CC of the other stage CC
The D camera 5B is set in focus at the Q position in the dark area B.

Then, the light source 4 is turned on, and the photosensitive drum 1
The CCD camera 5 while rotating the drive motor 7
A. The reflected light from the drum is received by 5B, and the output signal thereof is processed by the signal processing unit 6 in the subsequent stage to perform the defect inspection. FIG. 5 shows an example of the defect detection signal actually measured in this way. The horizontal axis represents the time axis and the vertical axis represents the fluctuation (amplitude) in the ± direction of the signal with reference to 0 point. Here, the waveform oscillated in the + direction represents a bright portion as compared with the reference value, and the waveform oscillated in the − direction represents a dark portion, and each peak point a, b of the waveform in the figure is a normal portion. In contrast, defect portions having a higher density (dark), c and d are defect portions having a lighter density (bright), of which a and c are defects with a clear contrast, b and
d represents a defect with little difference in shade. Further, according to the actual measurement, some signal fluctuation is observed even in a normal surface area where there is no defect on the photoconductor drum. Therefore, in the signal processing unit 6, a judgment level (broken line) that is a threshold value in the ± direction with respect to the reference value of 0 point Is set in advance, and when the signal from the CCD camera exceeds this determination level, it is determined as a defect and is output.

As a result, C corresponding to the bright portion A described above is obtained.
With the CD camera 5A, deep scratches on the surface of the photosensitive drum 1 and defects inside the photosensitive layer (dirt tube stain, C
The CCD camera 5B corresponding to the dark portion B can detect with high sensitivity foreign substances mixed in the G and CT layers, color irregularity due to abnormal coating, etc.
It has been confirmed that it is possible to detect irregularities and shallow scratches on the photosensitive layer surface with high sensitivity.

As CCD cameras 5A and 5B, 2
When 048 Bit, scanning speed: 2 MHz, and drum circumferential resolution: 78 μm are used, the number of scanning lines per second is 1000 lines / sec, and the circumferential detection speed is 78 mm.
Therefore, the time required to scan the entire circumference of the photosensitive drum 1 having an outer diameter of 30 mmφ (peripheral length 94.2 mm) is 94.2 / 78 = 1.2 seconds. The rotation speed of the photosensitive drum 1 is 50 rpm.

Embodiment 2 FIG. 3 shows an embodiment corresponding to claim 3 of the present invention. In this example,
A one-stage CCD camera 5 is arranged so as to focus on the P position on the surface of the photosensitive drum 1.
On the other hand, as a light source (fluorescent lamp), a light source 4A arranged so as to form a bright portion by irradiating the surface area at the P position with direct light.
And a light source 4B which is arranged so as to irradiate the surface area at the P position with scattered light so as to form a dark portion, and a light source 4B. Then, at the time of defect inspection, the light source 4A
And the light source 4B are alternately turned on in a short cycle, and the CCD camera 5
A bright portion and a dark portion are alternately formed at the focusing position P with respect to.

As a result, one stage of the CCD camera 5 detects a surface defect such as a deep scratch in the state where the P position on the drum surface is a bright part, and an internal defect having a clear gradation difference. In the state where the P position is switched to the state of the dark part, a shallow flaw surface defect and an internal defect having a small grayscale difference are detected. Therefore, by performing the defect inspection while rotating the photosensitive drum 1 in this state, a wide variety of surface defects and internal defects generated on the peripheral surface of the photosensitive drum 1 as in the above-described first embodiment. Can be accurately detected.

Embodiment 3 FIG. 4 shows an embodiment corresponding to claim 4 of the present invention. In this example,
The one-stage CCD camera 5 is arranged in focus on the P position on the surface of the photosensitive drum 1 as in the case of the above-described second embodiment. On the other hand, a lamp house 8 accommodating a fluorescent lamp is attached to the light source 4.
Slits 8a and 8b with shutters are formed on the front surface of the shutter so as to form a bright portion and a dark portion with respect to the P position, and the relative positions are displaced from each other.

Here, in the lamp house 8 of the light source 4, when the shutter of the slit 8a is opened, the direct light of the light source 4 is emitted to form a strip-shaped bright portion in the surface area at the P position.
On the other hand, when the shutter of the slit 8b is opened, the light rays reflected and scattered inside the lamp house are emitted to form a dark portion in the surface area at the P position. Then, with the light source 4 turned on, the slit 8
If the shutters a and 8b are alternately opened and closed in a short cycle, the bright portions and the dark portions are alternately formed at the focus position P of the CCD camera 5 as in the second embodiment. Therefore, while rotating the photosensitive drum 1 in this state, C
If a defect is detected through the CD camera 5, the first and second embodiments are performed.
As with the above, a wide variety of surface defects and internal defects can be accurately detected.

[0021]

As described above, according to the present invention, the defect detection is divided into the light portion and the dark portion formed on the surface of the photosensitive drum, and therefore, the conventional defect inspection apparatus is used. It is possible to accurately detect all of the various surface defects and internal defects of the photoconductor drum, which could not be achieved, and to provide a defect inspection device with high inspection capability.

[Brief description of drawings]

FIG. 1 is a configuration layout diagram of a defect inspection apparatus corresponding to a first embodiment of the present invention, in which (a) is a side view and (b) is an enlarged view of essential parts.

FIG. 2 is a front view of FIG.

FIG. 3 is a configuration diagram of a main part corresponding to a second embodiment of the present invention.

FIG. 4 is a configuration diagram of a main part corresponding to Noji 3 of the present invention.

FIG. 5 is a waveform diagram of a defect detection signal actually measured in the embodiment of the present invention.

6A and 6B are configuration diagrams of an organic photoconductor drum to which the present invention is applied, in which FIG. 6A is a side view of the drum, and FIG. 6B is a partially enlarged view of a photosensitive layer including defects.

FIG. 7 is a schematic diagram of a conventional photoelectric defect inspection apparatus.

[Explanation of symbols]

 1 Photoconductor drum 3 Photosensitive layer 4, 4A, 4B Light source 5, 5A, 5B CCD camera (line sensor) 6 Signal processing unit 7 Drive motor for drum rotation 8 Lamp house 8a, 8b Slit with shutter

Claims (4)

[Claims] 1. A defect inspection apparatus for a photosensitive drum, which detects defects such as scratches on the surface of the photosensitive drum, foreign substances mixed in the photosensitive layer, and uneven coating of the photosensitive layer. It is composed of a light source that irradiates light in the surface axis direction, a line sensor that receives the reflected light from the irradiation surface and detects the intensity of the light, a signal processing unit thereof, and a rotation driving unit of the photosensitive drum. A defect inspection apparatus for a photoconductor drum, wherein a line sensor is focused on a bright portion on which a direct light is applied and a dark portion on which a scattered light is applied, which are formed by irradiation of the light source on the surface of the photoconductor drum, to detect a defect. . 2. The defect inspection apparatus according to claim 1, wherein one light source is provided, and a light portion and a dark portion formed on the surface of the photoconductor drum by being irradiated with the light source are respectively focused to be a photoconductor. A defect inspection apparatus for a photosensitive drum, characterized in that two stage line sensors are arranged opposite to each other on the circumference of the drum. 3. The defect inspection apparatus according to claim 1, wherein the line sensor is one stage, and two light sources for forming a bright portion and a dark portion are provided at a focus position of the line sensor, and the light sources are alternately arranged. A defect inspection device for a photosensitive drum, which is lit up to detect a defect. 4. The defect inspection apparatus according to claim 1, wherein one line sensor and one light source are arranged, and the light source has a shutter for forming a bright portion and a dark portion at a focus position of the line sensor. A defect inspection apparatus for a photosensitive drum, comprising: a light-projecting slit attached thereto, wherein the shutter of each slit is alternately switched to detect a defect.