JPH05107196A - Surface layer defect detector - Google Patents

Abstract

PURPOSE:To enable the extraction of a correct defect signal by correcting sensor input signal levels with the determination of a mean thereof to eliminate effects of changes in the reflection factor per drum and changes in the photodetecting field of view because of rotary eccentricity. CONSTITUTION:Light is made to irradiate the surface of an object 1 to be inspected and a line sensor S and the object 1 to be inspected are moved relatively in a subscanning direction Y detecting reflected light with the sensor S having a number of photodetectors along the main scanning direction X to obtain a physical quantity Vi detected of the surface of the object 1 to be inspected. A mean Va of the physical quantity Vi is calculated by a means E1 for calculating a mean of the physical quantity detected. On the other hand, thresholds T1i, T2i and T3i set corresponding to a quantity of light detected of a non-defect surface calibrated almost the same as that of the object 1 to be inspected are stored into threshold memories M1 and M2. A detection correcting physical quantity (Vi-Va) is calculated with a subtractor 39 and a defect detection signal (0, 1) corresponding to a difference between the thresholds T1i, T2i and T3i is outputted from correctors C1 and C2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface layer of an object to be inspected having a substrate and a surface layer formed on the surface thereof, for example, a photosensitive drum used in an image output device such as a copying machine or a laser printer. The present invention relates to a surface layer defect detection device that detects defects such as a photosensitive layer on the surface.

[0002]

2. Description of the Related Art A photosensitive member such as a photosensitive drum or an endless photosensitive belt is used in a copying machine or a laser printer. Next, the structure of such a photosensitive member and the types of defects will be described with reference to FIG. In FIG. 14, a photosensitive member 01 is composed of a base material 02 such as aluminum and a photosensitive layer 03 formed on the surface thereof, and the photosensitive layer 03 is an undercoat layer 04 sequentially laminated on the base material 02, and a charge. Generation layer 0
5 and a charge transport layer 06. Defects that may occur on the surface of the photosensitive layer 03 of the photosensitive member 01 include subtle unevennesses 03a on the surface or defects "mechanical scratches" 03b such that the substrate 02 is exposed because the photosensitive layer 03 is completely peeled off.
There is. Further, when the charge transport layer 06 on the surface of the photosensitive layer 03 has a light-transmitting property, defects due to changes 05a and 06b in the respective thicknesses of the charge transport layer 06 or the charge generation layer 05 and impurities 07 in the photosensitive layer 03. Occurs.

The quality of such a photosensitive member 01 is ensured by a total number of surface inspections in order to prevent defects in copy image quality. The mechanical scratches 03b on the photosensitive member 01 are scratches that occur when the photosensitive member 01 is assembled into a unit. Due to the mechanical flaw 03b, black dots appear on the copy image quality, for example, in a blank copy state, or white dots occur in a solid black copy. The size of the mechanical scratch is 0.2 mm or more, the photosensitive member on the substrate is completely peeled off, and strong scattered light is emitted with respect to the slit light.

Further, when the photosensitive layer 03 is formed on the surface of the base material 02 in order to manufacture the photosensitive member 01, the undercoat layer 04, the charge generation layer 05, the charge transport layer 06 and the like are sequentially laminated, so that the photosensitive material is formed. It is necessary to perform the coating process and the vapor deposition process. In each of the above steps, "unevenness", "bulging", "dents", "streaks" due to coating and drying, and "dripping" of the coating liquid may occur. Especially in recent years, OPC, which has become a main force in the production of photosensitive materials, has become more sensitive and has a longer life.
In the case of (organic photosensitive member), the photosensitive material is applied in a plurality of layers for the purpose of function separation, and therefore defects such as the above-mentioned coating unevenness are likely to occur. These do not appear in the copy image quality in the black and white text originals that were mainly used in conventional copying machines, but the density which is an intermediate function between white and black, such as photographic originals, which is an important function of copying machines in recent years. It is a defect that appears as density unevenness in image quality in a required copy (halftone copy). Visually, the size is about 0.1 mm to 1 mm, but it is a very delicate defect and can be detected only after careful observation under a fluorescent lamp or the like.

As an inspection for these surface defects, a visual inspection has been conventionally performed by an inspector. However, the visual inspection has problems such as variation in inspection quality, increase in inspection man-hours, deterioration of working environment due to visual fatigue, difficulty in securing workers, and increase in worker training time. Therefore, a device for detecting surface layer defects for the purpose of automating the visual inspection work was first devised, and a utility model registration application has already been filed (Japanese Patent Application No. 2-10721). This application 2-10
The proposal proposed in No. 721 is that the halogen light spot light is made into slit light by an optical fiber bundle, condensed by a cylinder lens and projected on the surface of the photosensitive member, and scattered light from "mechanical scratches" is reduced by a line sensor by a reduction optical system. This is a method of receiving light.

According to the method of detecting the surface defect by receiving the scattered light from the mechanical scratch as in the invention of Japanese Patent Application No. 2-10721, the photosensitive layer on the surface is completely peeled off and the metal surface is exposed. It was effective against mechanical scratches and had the following features. That is, mechanical scratches generate strong scattered light due to projection of slit light by an optical fiber bundle of halogen light, which is 10 to 20 with respect to the angle of the regular reflection direction.
It was possible to receive light with the line sensor at the position shifted. However, since the thickness of each photosensitive layer applied in multiple layers is about 0.1 μm to several μm, defects such as “bulges” and “dents” due to subtle changes in film thickness (see 05a and 06a in FIG. 14) Almost no scattered light is generated for the slit light by the optical fiber bundle. For this reason, it is impossible for the line sensor to detect defects such as "dents" at a position shifted by 10 to 20 degrees from the direction of the regular reflection light which is the light receiving position. Further, a defect such as "mura" due to a change in film thickness needs to detect a difference in reflectance of about several percent, and cannot be detected by receiving scattered light according to the invention of Japanese Patent Application No. 2-10721. It was

A method of setting the light receiving position of the line sensor to the position of regular reflection light of the halogen light slit light is also considered as an application example of the invention of Japanese Patent Application No. 2-10721.
In the optical fiber array that converts halogen light into slit light, the unevenness of the light quantity is remarkably generated at the exit end face of the fiber, which becomes a noise component of the sensor signal,
The light from the fiber is aligned in the direction by the cylinder lens, so the sensor detects "waviness" with a period of several mm on the metal surface of the substrate, which has no problem in terms of photoreceptor function,
Since this becomes a noise component, it is difficult to extract only defects in the photoconductor coating layer. Further, the invention of Japanese Patent Application No. 2-10721 is a device of a mechanical device such as an optical system, and does not describe a method of processing a detection signal received by a line sensor.

The present inventor has invented a detection signal processing method for stably extracting a defect signal from a detection signal of a line sensor, and has already applied for a patent (Japanese Patent Application No. Hei 2-182980).
No.) The invention proposed in Japanese Patent Application No. 2-182980 measures the dark output Vi1 and the master drum for each light receiving element Si (i = 1, 2, ..., K) of the line sensor S as shown in FIG. This is a method of determining a threshold value Thi for each light receiving element Si from the light amount Vi2 and performing a scratch determination. That is,
A master drum that measures the dark output Vi1 of each light receiving element Si with respect to the temperature fluctuation of the output of the line sensor having k light receiving elements Si (i = 1, 2, ..., K) and receives the light by the line sensor. (Reference photosensitive drum having no defect) With respect to the amount of light reflected from the surface, each light receiving element Si of the line sensor
The detected light amount signal Vi2 (1, 2, ..., K) is measured for each.
Then, using the Vi1 and Vi2, the threshold value Thi is determined for each light receiving element Si as in the following expression (1). Thi = (Vi2−Vi1) × p + Vi1 (1) where i = 1, 2, ..., kp are constants and the photosensitive drum (photosensitive member) to be inspected When detecting a defect on the surface of the photosensitive member from the detected light amount Vi of each light receiving element Si from the surface, the threshold value Thi is used to determine whether the detection signal of each light receiving element Si of the line sensor S detects a defect. It is used as a threshold of. Threshold Thi
Is a fixed value, but the master drum is measured every lot exchange or temperature change, and the threshold value is updated. As a result, defect signals can be detected by correctly extracting scratch signals with respect to temperature fluctuations and light quantity fluctuations. The threshold value Thi is calculated by experimentally determining a defect signal level p for all types of surface defects detected in the inspection process, by setting a sample of a limit to be determined as a defect. According to the experiments conducted by the inventors, “defects of mechanical type” were p = 200% to 300% as the types of defects.

[0009]

SUMMARY OF THE INVENTION
4. The photosensitive member 01 shown in FIG. 4 is irradiated with strip-shaped white diffused light to determine the posture (or light receiving position) of the line sensor, and the detection posture for receiving reflected light from the center line portion of the strip-shaped light on the surface of the photosensitive layer 03 (band-shaped light It was confirmed that the defect detection signal generated by the changes 05a and 06a in the film thickness of the photosensitive layer 03 and the impurities 07 in the layer can be obtained by setting the center line light receiving position).
As described above, the Japanese Patent Application No. 2-18 proposed by the present inventor proposes a method of setting the detection posture of the line sensor to the band-shaped light receiving position.
When the fixed threshold value of the invention of No. 2980 is applied, the defect signal level such as “unevenness” generated in the coating step is about ± 10 to 50% compared to the signal level of the master drum,
The "mechanical flaw" is 200 to 300%, which is a very small defect signal level. Further, when the photosensitive layer defect is detected by this method, the reflectance varies due to the variation of the reflectance of each drum on a normal surface and the deviation of the light receiving optical axis due to the rotational eccentricity of the drum pipe. This causes a signal level fluctuation of about ± 20% on the normal surface of the photosensitive member.

Therefore, when the conventional "mechanical damage" is targeted, the signal variation of the normal surface of each drum is sufficiently smaller than the defect signal level.
It was possible to correctly determine a defect by the threshold setting method according to the invention of No. 182980. On the other hand, in the case of defects such as "unevenness" occurring in the coating process, the signal variation on the normal surface of each drum is approximately the same as the defect signal level. Therefore, in the fixed threshold value according to the invention of Japanese Patent Application No. 2-182980, The defect signal cannot be extracted correctly.

Further, as a conventional technique for detecting a photosensitive layer defect, an inspection device composed of a charger, a surface potential meter, a static eliminator, etc., as disclosed in JP-A-59-49573, is used. There is a method of measuring the surface potential of a member. When the fixed threshold value of the invention of the above-mentioned Japanese Patent Application No. 2-182980 proposed by the present inventor is applied to the method disclosed in Japanese Patent Laid-Open No. 59-49573, defects such as "unevenness" occur in the coating process. The signal level is about ± 10 to 50% of the signal level of the master drum, which means "mechanical damage".
Of 200 to 300% results in a very small defect signal level.

[0012] Further, variations in the measurement include variations in the charging sensitivity of the photosensitive member, fluctuations in the position of the electrometer probe during the measurement, and uneven charging of the charger, which cause a signal of about ± 20% on the normal surface of the photosensitive member. There is level fluctuation. Furthermore, since only the surface potential characteristics at the initial charging in the unexposed state can be inspected, it is impossible to detect the image quality defects such as "axis stripes" which appear in a halftone copy such as a photo original. .. "Axis line" is a type that cannot be observed at all by visual inspection of the photosensitive member due to the manifestation of malfunction of the photosensitive member due to the thickness change of the colorless and transparent "charge transport layer" on the outermost surface layer of the multilayer photosensitive member. It is based on the defect of. Therefore, the method of measuring the surface potential is the same as the method of setting the light-receiving visual field of the line sensor to the band-shaped light center line light-receiving position, as described in Japanese Patent Application No. 2-182.
The fixed signal according to the invention of No. 980 cannot correctly extract the defect signal.

The above description of the problems of the prior art is as follows.
Although it has been described as a problem at the time of detecting a defect of the photosensitive layer on the surface of the photoreceptor, the problem is that the surface layer other than the photosensitive layer,
This is also a problem in a defect detection apparatus for various surface layers that requires that various detectable physical quantities such as predetermined optical characteristics or surface potential characteristics be uniform. The present invention correctly extracts a defect signal with respect to a defect of a surface layer having a predetermined geometrical accuracy such as a surface of a photosensitive member or a predetermined physical characteristic, particularly a defect such as “unevenness” occurring in a coating process. An object of the present invention is to provide a surface layer defect detection device capable of performing the above.

[0014]

Next, the structure of the present invention devised to solve the above problems will be described. The constituent elements of the present invention correspond to those of the embodiments described later. For simplification, the reference numerals of the constituent elements of the embodiment are enclosed in parentheses. The reason why the present invention is described in association with the reference numerals of the embodiments described later is to facilitate understanding of the present invention and not to limit the scope of the present invention to the embodiments. In order to solve the above-mentioned problems, the surface layer defect detection device of the first invention of the present application is the surface of an object to be inspected (1) having a substrate (2) and a surface layer (3) formed on the surface thereof. The measurable physical quantity related to the state of the object to be inspected (1)
A surface layer defect detection apparatus that includes a physical quantity measuring device that detects while scanning in a main scanning direction and a sub-scanning direction that are orthogonal to the surface, and a surface layer defect detecting apparatus that detects a surface layer defect by a detected physical quantity detected by this physical quantity measuring device, Threshold value (T1i, T) set corresponding to the detected physical quantity of the surface of the inspected object having no defect, which is configured in substantially the same manner as the inspected object (1)
2i, T3i) and threshold value storage means (M1, M2), and detected physical quantity average value calculation means (Va) for calculating an average value (Va) of detected physical quantities obtained by scanning a predetermined portion of the surface of the inspection object (1) ( E1) and the detected physical quantity average value storage means (37) for storing the calculated detected physical quantity average value (Va).
And a detected correction physical quantity (Vi-Va) obtained by subtracting the detected physical quantity average value (Va) from the detected physical quantity Vi (i = 1, 2, ...) Obtained in the scan subsequent to the scanning of the predetermined portion and the threshold value ( Defect detection signal output means (C1, C2) for outputting a defect detection signal ("0", "1") corresponding to the difference between T1i, T2i, and T3i).

The surface layer defect detecting apparatus of the second invention of the present application is the same as the surface layer defect detecting apparatus of the first invention,
The physical quantity is a light quantity, and the physical quantity measuring device includes a light irradiating device (K) that irradiates the surface of the object (1) to be inspected with inspection light, and the surface layer (3) provided along the main scanning direction. ), A large number of light receiving elements (S
a line sensor (S) having an i) and a moving device (D) that relatively moves the line sensor (S) and the surface of the device under test (1) in the sub-scanning direction.
1i, T2i, T3i) is set for each of the light receiving elements (Si).

The surface layer defect detecting apparatus of the third invention of the present application is the same as the surface layer defect detecting apparatus of the first invention,
The physical quantity is an electric potential, and the physical quantity measuring device includes a charger (41) for uniformly charging the surface of the inspection object (1).
And a halftone exposure device (42) for performing halftone exposure with a light amount approximately equal to the amount of light reflected from the halftone original, and a small surface electrometer (S ') for measuring the potential of the surface of the inspection object (1).
And the micro surface electrometer (S ') and the object to be inspected (1)
And a moving device that relatively moves the surface in a main scanning direction and a sub scanning direction orthogonal to each other.

[0017]

In the surface layer defect detection apparatus according to the first aspect of the present application, the threshold value storage means (M1, M2) has a defect-free object having substantially the same structure as the object to be inspected (1) to be inspected. A threshold value (T1i, which is set corresponding to the physical quantity detected on the surface of the inspection object,
(T2i, T3i) is stored. Further, the physical quantity measuring device detects a measurable physical quantity related to the state of the surface of the inspection object (1) while scanning in the main scanning direction and the sub-scanning direction orthogonal to the surface of the inspection object. An average value (Va) of the detected physical quantity obtained by scanning a predetermined portion of the surface of the inspection object (1) is calculated by the detected physical quantity average value calculating means (E1). The calculated detected physical quantity average value (Va) is stored in the detected physical quantity average value storage means (37). Detection correction physical quantity (Vi-Va) obtained by subtracting the detected physical quantity average value (Va) from the detected physical quantity (Vi, i = 1, 2, ...) Obtained in the scan following the scan of the predetermined portion.
The defect detection signal (“0”, “1”) corresponding to the difference between the threshold value (T1i, T2i, T3i) is output from the defect detection signal output means (C1, C2).

Therefore, a value obtained by subtracting the average value (Va) of the detected physical quantities (Vi) of the respective portions on the surface of the inspection object (1) from the detected physical quantities (Vi, i = 1, 2, ...). The defect is detected by the signal corresponding to the difference between (Vi-Va) and the threshold value (T1i, T2i, T3i). Therefore, the average value (Va, m-1) of the detected physical quantity (Vi, m-1) in a certain part of the surface of the inspection object (1) and the average value of the detected physical quantity (Vi, n-1) in the other part. Even if there are variations with (Va, n-1), these variations can be compensated for, so that defects can be detected using the same threshold values (T1i, T2i, T3i).

Further, the surface layer defect detecting device of the second invention of the present application adopts the light quantity as the physical quantity to be detected. Then, the surface layer defect detection device of the second invention of the present application,
The threshold value storage means (M1, M2) receives light of each of the line sensors (S) corresponding to the amount of detected light on the surface of the inspected object having no defect, which is configured in substantially the same manner as the inspected object (1) to be inspected. The threshold values (T1i, T2i, T3i) set for each element (Si) are stored. Further, the physical quantity measuring device is provided with a light irradiation device (K), and the light irradiation device (K) irradiates the surface layer (3) of the inspection object (1) with inspection light.
A large number of light-receiving elements (Si) provided along the main scanning direction
The line sensor (S) having the surface layer (3)
The amount of reflected light from is detected. The line sensor (S) and the surface of the device under test (1) are relatively moved in the sub-scanning direction by the moving device (D). Therefore,
The line sensor (S) can detect the amount of reflected light from the entire surface of the surface of the inspection object (1) in the main scanning direction and the sub scanning direction.

From the detected light quantity (Vi) obtained by scanning a predetermined portion of the surface of the object (1) to be inspected, an average value (Va) is calculated by the detected physical quantity average value calculating means (E1). The calculated average value (Va) of the detected light quantity (Vi) is stored in the detected physical quantity average value storage means (37). Detected light amount Vi obtained in the scan following the scan of the predetermined portion
Defects corresponding to the difference between the detected correction light amount (Vi-Va) obtained by subtracting the average value (Va) of the detected light amount (Vi) from (i = 1, 2, ...) And the threshold value (T1i, T2i, T3i). The detection signal (“0”, “1”) is the defect detection signal output means (C
It is output from 1, C2).

Further, the surface layer defect detecting device of the third invention of the present application employs a potential as a physical quantity to be detected. Then, the surface layer defect detection device of the third invention of the present application,
Thresholds (T1i, T2i) set in the threshold value storage means (M1, M2) corresponding to the detected potential of the defect-free surface of the object to be inspected having substantially the same structure as the object to be inspected (1) to be inspected. )
Is remembered. In addition, the charger (4
In 1), the surface of the device under test (1) is uniformly charged.
A halftone exposure device (42) performs uniform halftone exposure on the surface of the charged object (1) to be inspected with a light amount similar to the amount of light reflected from the halftone original. The small surface electrometer (S ') for measuring the potential of the surface of the object to be inspected (1) and the surface of the object to be inspected (1) are orthogonal to each other by the moving device (D) in the main scanning direction and the sub-scanning direction. Can be moved relative to each other. Therefore, the minute surface electrometer (S ′) can detect the surface potential of the entire surface of the surface of the inspection object (1) in the main scanning direction and the sub scanning direction.

An average value (Va) is calculated by the detected physical quantity average value calculation means (E1) from the detected surface potential (Vi) obtained by scanning a predetermined portion of the surface of the object to be inspected (1). The calculated average value (Va) of the detected surface potential (Vi) is stored in the detected physical quantity average value storage means (37). Detection correction surface potential (Vi-V) obtained by subtracting the average value (Va) of the detected surface potential from the detected surface potential Vi (i = 1, 2, ...) Obtained in the scan subsequent to the scanning of the predetermined portion.
The defect detection signal ("0", "1") corresponding to the difference between a) and the threshold value (T1i, T2i) is output from the defect detection signal output means (C1, C2).

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the surface layer defect detecting device of the present invention will be described with reference to the drawings. 1, FIG. 2 and FIG. 3 are schematic explanatory views of the configuration of the first embodiment of the surface layer defect detection apparatus.
Is a schematic perspective view, and FIGS. 2 and 3 are plan views of FIG. 2 is a diagram showing a state in which the line sensor S of the surface layer defect detection device of this embodiment is held in a first detection posture P1 (described later), and FIG. 3 is a second detection posture P2 (described later). It is a figure which shows the state currently hold | maintained at. In this first embodiment, the light quantity is used as the detected physical quantity. In FIGS. 1, 2 and 3, the photosensitive drum 1 as the inspection object is the same as that shown in FIG.
It has a structure substantially similar to that of the photoconductor 01 shown in FIG. 1 and is composed of a cylindrical aluminum base material 2 and a multi-layered organic translucent photosensitive layer (surface layer) 3 formed on the surface thereof. There is. As shown in FIGS. 2 and 3, the photosensitive layer 3 is composed of a charge transport layer 4, a charge generation layer 5 and a charge transport layer 6 which are sequentially laminated on the surface of the aluminum base material 2. The drum supporting device D that supports the photosensitive drum 1 includes a case 11. A drum support member 12 is rotatably supported on the upper surface of the case 11. Drum support member 1
A drum mounting portion on which the photosensitive drum 1 is mounted is formed on the upper surface of 2, and a gear 13 is provided on the lower surface. In the case 11, the stepping motor 14
The drive gear 15 fixed to the output shaft of the stepping motor 14 meshes with the gear 13. Therefore, the photosensitive drum 1 mounted on the drum support member 12 is rotationally driven by the stepping motor 14 at a constant rotational speed.

A light irradiating device K for irradiating the surface of the photosensitive drum 1 with a belt-like light (slit light) for inspection parallel to its axis is a fluorescent lamp 16 as a white diffused light source and a reflecting mirror 17.
And a slit forming plate 18. The slit forming plate 18 is provided with a slit 18a. In the light irradiation device K, the band-shaped light (hereinafter, also referred to as “slit light”) of the white diffused light emitted from the slit 18a is formed on the surface of the photosensitive drum 1 mounted on the drum supporting member 12 so that the photosensitive drum 1 is exposed. It is arranged to irradiate parallel to the axis. In this embodiment, the distance from the slit 18a to the surface of the photosensitive drum 1 is about 100 mm, the vertical width of the slit light is about 15 mm, and the photosensitive drum 1 is φ84 mm.
The width of the slit light on the surface is set to about 5 mm. Fluorescent lamps are generally suitable as the light source used in the present invention because the illuminance of the diffusion surface is high and the uniformity of the light amount distribution is good.

According to the experiment, as the type of the fluorescent lamp used for the inspection of the photosensitive layer 3, the type used for improving the color rendering property is 3
A white fluorescent lamp having a relatively wide spectral distribution is suitable for a wavelength range arc tube. This is because the spectral distribution of the three-wavelength arc tube is concentrated in three types of wavelengths, and therefore interference light is likely to be generated between the surface of the photosensitive layer and the surface of the lower photosensitive layer, which appears as signal noise. Is. On the other hand, the white fluorescent lamp has a relatively wide spectral distribution, and the interference light is less generated. A perfect diffused light source is desirable to detect subtle unevenness on the surface of the photosensitive drum with high sensitivity by reflected light at the boundary portion of the slit light on the surface of the photosensitive drum 1, and sensitivity of a failure signal. For improvement, the higher the contrast of the boundary, the better. For this purpose, the back reflector 12 of the fluorescent light slit light device may be subjected to a non-reflective treatment such as matte black coating so as to suppress the secondary reflection by the back reflector. It is preferable to use one having a small illuminance distribution and a high light amount at the front opening. In order to improve the sensor signal level, the direct current lighting system is preferable to the commercial frequency lighting or high frequency lighting system for the fluorescent lamp light source. According to experiments, the direct current lighting system has improved the illuminance by about 10% as compared with the commercial frequency lighting.

The line sensor S supported by the line sensor support device U so as to be capable of adjusting its posture around the X, Y, and Z axes orthogonal to each other is 2 to 12 arranged along the longitudinal direction (that is, the X axis). Power = 4096 light receiving elements Si (i
= 1, 2, ... 4096) (see FIGS. 2 and 3) and a reduction optical system Sa for forming a slit light image irradiated on the surface of the photosensitive drum 1 on each of these light receiving elements Si. ..

The line sensor support device U includes a rotary table 21 which is rotationally adjusted about the X axis extending in the longitudinal direction of the line sensor S. On the rotary table 21, a Z-axis swing table 22 is swingable around a Y-axis parallel to the optical axis of the line sensor S and an axis perpendicular to the X-axis.
It is supported so that the posture around the axis can be adjusted. On the Z-axis swing table 22, a Y-axis swing table 23 that is swingable around the Y-axis parallel to the optical axis of the line sensor S is supported so that the attitude around the Y-axis can be adjusted. Therefore, in the line sensor support device U, the posture of the line sensor S is set at the position of the boundary line portion whose light-receiving field extends on the surface of the photosensitive drum 1 in the longitudinal direction of the slit light image.
1st detection posture (slit light boundary line receiving posture) P1
And the second detection posture (slit light center line light receiving posture) P2 shown in FIG. 3 in which the light receiving field is set at the center line portion extending in the longitudinal direction of the slit light image on the surface of the photosensitive drum 1. It has the function of holding.

The adjustment accuracy of the detection posture of the line sensor S is 10 which is the sensor resolution on the inspection surface (photosensitive drum surface).
It is sufficient that the position adjustment resolution and the position repeatability of the two light-receiving fields (the light-receiving fields of the first or second detection positions of the line sensor S) of the posture adjustment are φ84 to be inspected drum (photosensitive drum). It is about 0.01 degree when 1 is received with an optical magnification of about 5 times, and these can be easily realized by a commercially available automatic stage whose posture can be adjusted around three axes. As for the positional relationship between the line sensor S and the light irradiation device K, as shown in FIGS. 2 and 3, the light projection angle 24 of the light irradiation device K and the light reception angle 25 of the line sensor S are equal. As a result, the line sensor S can receive the slit light image of the slit light of the light irradiation device K which is imaged on the photosensitive layer 3 at the position of receiving the specular reflection light. The angles 24 and 25 can be arranged up to about 5 degrees to 60 degrees, but particularly 10 to
Defects of about 20 degrees are easy to detect.

FIG. 4 is a circuit portion of the photosensitive layer defect detecting device shown in FIGS. 1, 2 and 3, that is, defect detection signal output means E.
FIG. In FIG. 4, the 4096 (2 to the 12th power) light receiving elements Si (i = 1 to 4) of the line sensor S are arranged.
The detected light amount signal detected in 096) is input to the A / D (analog / digital) converter 31. The A / D converter 31 converts the input signal (the detected light amount signal) into a 6-bit digital signal, that is, a 6th power of 2 = 64-level digital light amount detection signal Vi (i = 1 to 4096) and adds it. Is output to 32.

The adder 32 adds the digital light amount detection signal of each light receiving element Si input from the A / D converter 31 and the output signal of the latch 33 and outputs the result to the latch 33. In this embodiment, the latch 33 is composed of an 18-bit memory, and the 6-bit digital light amount detection signal Vi output from each of the 2 @ 12 light receiving elements Si (i = 1 to 4096) is output in one line. It is configured to be able to store minutes. The adder 32 and the latch 33 are operated by the sampling clock signal 34 having the same cycle as the drive signal of the line sensor S, and the latch 33 has the sum ΣVi of the light amount detection signals Vi for one main scanning line of the light receiving element Si. Are configured to be latched.

The latch 33 outputs the latch signal of the latch 33 to the shift register 37 every time the counter 36 for counting the start pulse 35 which is the scanning start signal for each main scanning line counts "1". The latch data is reset at the same time. Therefore, every time the counter 36 counts "1", the shift register 37 always receives the light receiving element Si.
The total sum of the detected light amounts for one line is output.

The output signal of the counter 36 is the register 3
It is also entered in 8. This register 38 is the counter 3
It has a function of shifting the data held in the shift register 37, to which the sum of the detected light amounts for one line of the light receiving element Si is input, to the lower side by 12 bits in accordance with the input signal from 6. The held data in the shift register 37, which is obtained by shifting the held data to the lower side by 12 bits, is
The average value Va of the detected light amounts detected by the 4096 (2 to the 12th power) light receiving elements Si is obtained.

In this embodiment, the average value Va of the detected light amount of each light receiving element Si is held in the shift register 37 every time one main scanning line is scanned. The value Va can be held in the shift register 37 every time the main scanning line is scanned for n lines. For example, the average value Va
Can be detected every time 4 main scanning lines (2 squared lines) are scanned. In this case, in the above-described embodiment, the memory of the latch 33 has a 20-bit configuration, the counter 36 is configured to output a signal to the latch 33 and the register 38 each time 4 lines are counted, and the lower register of the shift register 37 is configured. The shift to the side may be 14 bits. With such a configuration, the average value Va output from the shift register 37 can be an average value of the detected light amounts of four main scanning lines.

The digital detected light amount signal Vi of each light receiving element Si output from the A / D converter 31 and the average value Va of the detected light amount output from the shift register 37 are calculated by the subtractor 3
9 has been entered. The subtractor 39 outputs the difference Vi-Va between the input signals Vi and Va, and the difference Vi-Va is input to the comparators (that is, defect detection signal output means) C1 and C2. The output signals of the threshold memories M1 and M2 are input to the comparators C1 and C2. The threshold memory M1 has thresholds T11 and T1.
2, ... T1n (n = 4096) and threshold values T21, T22, ... T2
n (n = 4096) is stored. Thresholds T11, T12, ...
T1n (n = 4096) is the 6-bit digital detection light amount signal Vi of each light receiving element Si when the line sensor S is in the first detection posture (slit light boundary line receiving posture) P1.
Is a positive 6-bit threshold value to be compared with
21, T22, ... T2n (n = 4096) are the 6-bit digital detection light amount signals Vi of the respective light receiving elements Si when the line sensor S is in the second detection posture (slit light center line light receiving posture) P2. 6-bit threshold value on the plus side compared with.

The threshold memory M2 has thresholds T31, T32, ...
T3n (n = 4096) is stored. Threshold values T31, T32,
T3n (n = 4096) is compared with the 6-bit digital detection light amount signal Vi of each light receiving element Si when the line sensor S is in the second detection posture (slit light boundary receiving posture) P2. It is a side 6-bit threshold value. Each of the thresholds T11, T12, ... T1n (n = 4096), thresholds T21, T2
2, ... T2n (n = 4096) and threshold values T31, T32, ... T3
n (n = 4096) is a threshold value set corresponding to the detected light amount signal on the surface of the photoconductor drum 1 having substantially the same structure as that of the photoconductor drum 1 to be inspected.

Each of the threshold memories M1 and M2 receives a threshold selection signal A (see FIG. 4) corresponding to the detected posture of the line sensor S and a read clock signal B having the same cycle as the sampling clock signal 34, and the threshold T1i. (I = 1,
2, ..., N, n = 4096), or T2i, T3i are read out. That is, when the threshold selection signal A is "0" corresponding to the first detection position P1, the 6-bit threshold T1i is read from the threshold memory M1 and "0" is output from the threshold memory M2. Also,
When the threshold selection signal A is "1" corresponding to the second detection position P2, the 6-bit threshold T2 is read from the threshold memory M2.
i is read out, and the threshold value T3i is output from the threshold value memory M2.

The comparator C1 has a difference Vi- between Vi-Va + Vo obtained by adding a constant value Vo to the input Vi-Va and a threshold value T1i or T2i called from the threshold value memory M1.
Va-Vo-T1i (or T2i) is calculated and the calculated value is output to the defect determination circuit H1. The defect discrimination circuit H1 is
When the calculated value is positive, the defect detection signal is output. Further, the comparator C2 obtains Vi-Va + obtained by adding a constant value Vo to the input Vi-Va.
Difference V between Vo and the threshold T3i called from the threshold memory M2
i-Va-Vo-T3i is calculated and the calculated value is output to the defect discrimination circuit H2. The defect determination circuit H2 is configured to output a defect detection signal when the calculated value is negative. Detected physical quantity average value calculation means (that is, detected light quantity average value calculation means) E1 is configured from the components indicated by the reference numerals 32 to 38, and the detected physical quantity average value storage means (that is, detected A light amount average value storage means) is configured. Further, the defect signal extracting means E is composed of the components indicated by the reference numerals 31 to 39, C1, C2, H1, H2, M1 and M2.

Next, the operation of the first embodiment of the surface layer defect detecting device of the present invention having the above-mentioned structure will be described. The light emitted from the fluorescent lamp 16 as the white diffused light source of the light irradiating device K is applied to the surface of the photosensitive drum 1 by the slit 18a as strip-shaped slit light parallel to the direction of the light receiving element Si row of the line sensor S. It In this state, the light receiving visual field of the line sensor S is set to the boundary line portion extending in the longitudinal direction of the band-shaped slit light on the surface of the photosensitive drum 1. That is, the line sensor S is held in the first detection posture P1. Then, the line sensor 3 receives the reflected and scattered light of the slit light from the surface of the photosensitive drum 1 to perform the main scanning, and the drum supporting member 12 of the drum supporting device D is rotated to make a line with the surface of the photosensitive drum 1. The sensor S is relatively moved in the sub scanning direction. In this embodiment, the scanning speed is about 1 KHz for main scanning and about 0.2 rotations / second for sub-scanning. Band-shaped white diffused light (slit light) irradiated on the surface of the photosensitive drum 1
Is reflected by the surface of the base material 2 and the light-transmissive photosensitive layer 3 having a multi-layer structure laminated on the surface. When the line sensor S is held in the first detection posture P1, the presence of irregularities on the boundary line portion extending in the longitudinal direction of the band-shaped slit light on the surface of the photosensitive layer 3 or the photosensitive layer 3 is completely peeled off Due to the presence of a defect in which the lower substrate 2 is exposed, the light amount detection signal from each light receiving element Si of the line sensor S changes.

That is, as can be seen from FIG. 4, the amount of light reflected from the boundary line portion of the slit light on the surface of the photosensitive drum 1 is detected by each light receiving element Si of the line sensor S, and sequentially digitalized by the A / D converter 31. The detected light amount signal Vi is converted. The first value V1 (digital detection light amount signal of the first line detected by the light receiving element S1) of the 6-bit digital detection light amount signal input from the A / D converter 31 to the adder 32 is output from the latch 33. Do 1
8-bit signal "0000000000000000"
0 ”is added. The output signal of the adder 32 at this time is V1, which is latched by the latch 33. Next, the value V2 of the digital detection light amount signal input to the adder 32
The (digital detection light amount signal detected by the light receiving element S2) is added to the digital detection light amount signal V1 output from the latch 33. The output signal of the adder 32 at this time is V1 + V2. When the scanning of one main scanning line is performed in this manner, the latch 33 is set to one of the main scanning lines.
The total sum of the detected light amount signals for the lines is latched.

When the scanning of one line of the main scanning line is completed and the scanning of the next line, that is, the second line is started, the counter 36 for counting the start pulse 35 which is the scanning start signal outputs "1". Count and latch 33
And outputs a signal to the register 38. This counter 3
By the output signal of 6, the latch signal of the latch 33 (the sum of the detected light amount signals for one main scanning line) is output to the shift register 37, and the signal held in the latch 33 is reset. Therefore, every time the counter 36 counts "1", the total sum of the detected light amounts for one line of the light receiving element Si is always output to the shift register 37.

The register 38 to which the output signal of the counter 36 is input shifts the data held in the shift register 37, to which the total amount of detected light for one line of the light receiving element Si is input, to the lower side by 12 bits. .. The held data in the shift register 37 obtained by shifting the held data to the lower side by 12 bits is 4096 (2 to the 12th power).
1 detected by each of the light receiving elements Si (i = 1 to 4096)
Average value Va of the detected light intensity Vi (i = 1 to 4096) for the line
(= ΣVi / 4096).

On the other hand, the digital detection light amount signal Vi for the first one of the main scanning lines is input to the adder 32 and the subtractor 39. However, the output of the shift register 37 is 0 during scanning of the first one main scanning line. Therefore, the output of the subtractor 39 during the scanning of the first one line is
It becomes Vi-0. The defect discrimination signal of the defect discrimination circuit H1 obtained by scanning the first one line is ignored in this embodiment. In this case, in the first scanning of one line, the defect determination of that line is not performed,
By rotating the photosensitive drum 1 once and then rotating it for another line to perform defect determination, the defect determination for the first one line can be performed.

In the scanning of the second and subsequent main scanning lines, the digital detected light amount signal Vi from the A / D converter 31 and the average value Va of the detected light amount one line before are input to the subtractor 39. .. In this case, for example, the average value Va, m-1 of the digital detection light amount signal shown in FIG. 5 is obtained by scanning the m-1th line, and the average value Va, m-1 of the digital detection light amount signal shown in FIG.
A digital detection light amount signal Vi, m shown in is obtained. Also,
The scanning of the n-1th line obtains the average value Va, n-1 of the digital detection light amount signal shown in FIG. 5, and the scanning of the nth line obtains the digital detection light amount signal Vi, n shown in FIG. In the case shown in FIG. 5, the average value Va, m-1 of the reflected light amount of the photosensitive layer 3 output from the shift register 37 during the scanning of the m-th line is obtained from the shift register 37 during the scanning of the n-th line. Average value of reflected light output Va, n-1
Will be greater than.

In this case, it means that the average value of the amount of reflected light is different in the vicinity of the portion for scanning the m-th line of the photosensitive drum 1 and in the vicinity of the portion for scanning the n-th line. In such a case, the same threshold value is applied to the digital detection light amount signal Vi, m obtained by scanning the m-th line and the digital detection light amount signal Vi, n obtained by scanning the n-th line. Defect determination cannot be performed.

Therefore, when Vi-Va is calculated for all the light receiving elements Si (i = 1, 2, ..., 4096) by the subtractor 39, the digital detection light amount signal Vi, m, of the m-th and n-th lines is calculated. Data V as shown in FIGS. 6A and 6B with respect to Vi, n
i, m-Va, m-1, and Vi, n-Va, n-1 are obtained. However, the V
a, m-1 and Va, n-1 are average values of the digital detection light amount signals of the light receiving elements Si of the m-1th line and the n-1th line, respectively.

Vi-Va output from the subtractor 39 is the comparator C.
Input to 1 and C2. When the photoconductor drum 1 is held at the first detection position, the threshold selection signal A is "0" corresponding to the first detection position P1, and at this time, the 6-bit threshold T1i from the threshold memory M1. Is read out and 0 is output from the threshold memory M2. in this case,
The comparator C1 compares a value obtained by adding a constant value Vo to the input signal Vi-Va from the subtractor 39, that is, Vi-Va + Vo, with the input signal T1i from the threshold value memory M1. The constant value Vo
The reason for adding is to unify the value of the detected light amount to be compared with the threshold value T1i by the comparator C1 to a positive value and to unify the data value of the threshold value T1i to a positive value.

All the light receiving elements Si (i = 1, 1,
2, ..., 4096), Vi-Va + Vo is calculated, and the digital detected light amount signal Vi, of the m-th and n-th lines is calculated.
The data Vi, m-Va, m-1 + Vo and Vi, n-Va, n-1 + Vo as shown by the solid lines in FIGS. 7A and 7B are obtained for m and Vi, n. Data Vi, m-V shown in FIGS. 7A and 7B
a, m-1 + Vo and Vi, n-Va, n-1 + Vo are the amounts of reflected light in the vicinity of the portion for scanning the m-th line of the photosensitive drum 1 and in the vicinity of the portion for scanning the n-th line. It is a digital detection light amount signal in which the variation of the average value is corrected. Digital detection light amount signals Vi, m-Va, m-1 + Vo and V shown in FIGS. 7A and 7B in which the variation in the average value of the reflected light amount is corrected.
For i, n-Va, n-1 + Vo, the same threshold value T1i (see FIG.
Defect determination can be performed by applying (see dotted lines A and 7B).

The comparator C1 has a threshold value memory corresponding to the value Vi-Va + Vo obtained by adding Vo to the signal Vi-Va input for each light receiving element Si input from the subtractor 39, and each light receiving element Si. Vi which is the difference from the threshold value T1i read from M1
-Va + Vo-T1i (see FIGS. 7A and 7B, provided that FIG. 7A,
In 7B, the subscripts ", m" and ", n" are added to the values of Vi on the m-th line and the n-th line, and the subscripts are added to the values of Va on the m-1th line and the n-1th line. , m-1 "
And ", n-1" are added. ) Is output to the defect discrimination circuit H1. As can be seen from FIGS. 7A and 7B, when Vi−Va + Vo is smaller than T1i, Vi−Va
+ Vo-T1i has a negative value, but if it is large, then Vi-Va
+ Vo-T1i becomes a positive value. The comparator C1 has the above-mentioned Vi-
When the value of Va + Vo-T1i is negative, "0" is output, and when the value is positive, "1" is output. The defect discrimination circuit H1 stores "0" when the output signal of the comparator C1 is "0", and stores "1" when it is positive. That is, the defect discrimination circuit H1
Stores the detection signal of each light receiving element Si after binarizing it.

FIGS. 8A and 8B are explanatory views of a signal obtained by binarizing the output signal of the comparator C1 and are signals obtained from the signals of FIGS. 7A and 7B. When the output signal of the comparator C1 has a positive value, that is, it means that there is a defect in the photosensitive layer 3 of the photosensitive drum 1 corresponding to the portion in which the defect determination circuit H1 stores "1". Since the defect is detected for each light receiving element Si, the size of the area of the defective portion can be determined.

When the line sensor S is held in the first detection posture P1, the digital detection light amount signal of each light receiving element Si changes in the positive direction according to the presence of the unevenness on the surface of the photosensitive layer 3. The defect detection signal changing in the negative direction does not appear. Therefore, in the light quantity measurement by the line sensor S in the first detection posture P1, the threshold value in the negative direction is unnecessary, and therefore the threshold value output from the threshold value memory M2 is set to zero.

As described above, the photosensitive drum 1 is set to 1 while the line sensor S is held in the first detection posture P1.
After inspecting the entire surface of the line sensor by rotating it more than once, the rotary table 21 of the line sensor supporting device U is rotated,
The light receiving field of the line sensor S is set to the center line extending in the longitudinal direction of the strip-shaped slit light on the surface of the photoconductor. That is, the line sensor S is held in the second detection posture P2. When the line sensor S is held in the second detection posture P2, changes in the film thicknesses of the light-transmissive layers (for example, the charge generation layers 4 and 6 and the charge transport layer 5) that form the photosensitive layer 3 and The presence of impurities in each layer indicates that the light amount detection signal from each light receiving element Si of the line sensor S is abnormal (that is,
Detected (as a defect detection signal).

Even when the line sensor S is held in the second detection posture P2, the output signal of the subtractor 39 is Vi-Va, as in the case where the line sensor S is held in the first detection posture P1. In the case of the second detection posture P2, the threshold selection signal A is "1" corresponding to the second detection position P2, and at this time, the threshold memory M2 outputs the 6-bit threshold T2i, and the threshold memory The threshold value T3i is output from M2. In this case, the comparator C1 has a value obtained by adding a constant value Vo to the input signal Vi-Va from the subtractor 39, that is, Vi-V.
A + Vo is compared with the input signal T2i from the threshold memory M1. Further, the comparator C2 has a value obtained by adding a constant value Vo to the input signal Vi-Va from the subtractor 39, that is, Vi-Va + Vo.
And the input signal T3i from the threshold memory M2 are compared.

In the comparators C1 and C2, all the light receiving elements Si (i =
1, 2, ..., 4096), Vi-Va + Vo is calculated, and the digital detected light amount signal Vi, of the m-th and n-th lines is calculated.
The data Vi, m-Va, m-1 + Vo and Vi, n-Va, n-1 + Vo as shown by the solid lines in FIGS. 9A and 9B are obtained for m and Vi, n. The data Vi, m-Va, m-1 + V0 and Vi, n-Va, n-1 + V0 of the m-th and n-th lines shown in FIGS. 9A and 9B are
It is a digital detection light amount signal in which the variation in the average value of the reflected light amount between the vicinity of the portion for scanning the m-th line of the photosensitive drum 1 and the vicinity of the portion for scanning the n-th line is corrected. The digital detection light amount signals Vi, m-Va, m-1 + V0 and Vi, n-Va, n-1 + Vo of the respective lines (the m-th line and the n-th line) corrected for variations in the average value of the reflected light amount.
The same threshold values T2i and T3i (see the dotted lines in FIGS. 9A and 9B) can be applied to the defect determination.

That is, the comparator C1 receives the signal Vi-Va input for each light receiving element Si input from the subtractor 39.
And the value of the light receiving element Si
Vi−Va + Vo−T2i which is the difference from the threshold value T2i read from the threshold value memory M1 in correspondence with (see FIGS. 9A and 9B,
However, in FIGS. 9A and 9B, the m-th line and the n-th line
Subscripts ", m" and ", n" are added to the value of Vi of the line, and subscripts ", m-1" and ", n- are added to the value of Va of the m-1th line and the n-1th line. 1 ”is added. ) Is output to the defect discrimination circuit H1. Further, the comparator C2 has a difference between the signal Vi-Va + Vo and the threshold value T3i read from the threshold value memory M2, Vi-Va + Vo-.
A signal corresponding to T3i is output to the defect discrimination circuit H2.

As can be seen from FIGS. 9A and 9B, Vi-Va +
When Vo is smaller than T2i, Vi-Va + Vo-T2i has a negative value, and when it is larger, Vi-Va + Vo-T2i has a positive value. The comparator C1 outputs "0" when the value of Vi-Va + Vo-T2i is negative, and outputs "1" when it is positive. The defect discrimination circuit H1 stores "0" when the output signal of the comparator C1 is "0", and stores "1" when it is positive. That is, the defect determination circuit H1 binarizes and stores the detection signal of each light receiving element Si.

As can be seen from FIGS. 9A and 9B, Vi
If −Va + Vo is larger than T3i, then Vi−Va + Vo−
T3i has a positive value, but when it is small, Vi-Va + Vo-
T3i becomes a negative value. The comparator C2 has the above-mentioned Vi-Va + Vo.
When the value of -T3i is positive, "0" is output, and when it is negative, "1" is output. The defect discrimination circuit H2 stores "0" when the output signal of the comparator C1 is "0", and stores "1" when it is positive. That is, the defect determination circuit H2 binarizes and stores the detection signal of each light receiving element Si.

The upper graphs of FIGS. 10A and 10B are explanatory diagrams of the binarized signal output from the comparator C1 (the signal obtained by comparison with the threshold value T2i), and the lower graphs of FIGS. 10A and 10B are: It is explanatory drawing of the binarized signal (signal obtained by comparison with threshold value T3i) which the comparator C2 outputs. 10A is a signal obtained from the signal of FIG. 9A, and FIG. 10B is a signal obtained from the signal of FIG. 9B. The defect discrimination circuits H1 and H2 correspond to the part storing "1" (that is, the part where the output signal of the comparator C1 has a positive value and the part where the output signal of the comparator C2 has a negative value). This means that the photosensitive layer 3 of the photosensitive drum 1 has a defect. Since the defect is detected for each light receiving element Si, the size of the area of the defective portion can be determined.

Note that the line sensor S1 has the second detection posture P.
The defects detected when the number 2 exists are the light-transmitting layers forming the photosensitive layer 3 (for example, the charge generation layer 6 and the charge transport layer 5).
Is a defect due to the change in each film thickness and the presence of impurities in each layer.

In the first embodiment, the fluorescent lamp 16 for emitting white scattered light and the slit 18a are used in the light irradiation device. The fluorescent lamp 16 is inexpensive and commercially available, and can emit complete diffused light easily, so that the light irradiation device K can be manufactured at low cost. Further, in the above-described embodiment, the light receiving visual field of the line sensor S is set at two positions, that is, the boundary line portion extending in the longitudinal direction of the image of the slit light projected on the surface of the photosensitive drum 1 and the position of the center line. It is possible to detect irregularities on the surface of the photosensitive layer 3 and also to detect defects such as the above-mentioned “color unevenness” and “stains” due to subtle changes in the film thickness of the photosensitive layer 3 composed of multiple layers. Further, in the first embodiment, since the reduction optical system Sa is used as means for forming the slit light image irradiated on the surface of the photosensitive drum 1 on the light receiving element Si of the line sensor S, the apparatus can be downsized. It will be possible. Furthermore, a defect on the surface portion of the photosensitive layer 3 is detected by detecting the reflected light from the boundary line portion of the surface of the photosensitive layer 3 which extends in the longitudinal direction of the slit light, and from the center line portion of the slit light. Since the defect inside the photosensitive layer 3 can be detected by the reflected light of, the defect type can be classified.

Next, a second embodiment of the surface layer defect detecting device of the present invention will be described with reference to FIGS. In the second embodiment, the photosensitive drum 1 as the inspection object
Is the same as that of the first embodiment. And
The second embodiment differs from the first embodiment in which the light amount is used in that the surface potential is used as a detection physical quantity for detecting defects in the surface layer. The signal processing circuit for detecting the defect detection signal from the detected physical quantity (surface potential) uses a circuit substantially similar to that of the first embodiment. In the following description of the second embodiment, elements corresponding to those of the first embodiment are designated by the same reference numerals as those used in the first embodiment, and detailed description thereof will be omitted.

In FIGS. 11 and 12, a photosensitive drum 1 as an object to be inspected has substantially the same structure as the photosensitive member 01 shown in FIG. 14, and is formed on a cylindrical aluminum base material 2 and its surface. And an organic light-transmitting photosensitive layer (surface layer) 3 having a multilayer structure. As shown in FIG. 12, the photosensitive layer 3 includes a charge transport layer 4, a charge generation layer 5, and a charge transport layer 6 which are sequentially laminated on the surface of the aluminum base material 2.
It consists of

The photosensitive drum 1 is rotatably supported by the drum supporting device D similar to that of the first embodiment. Around the photoconductor drum 1 supported by the drum supporting device D, a charger 41, a halftone exposure device 42, a fine surface electrometer S ′, and a static eliminator 46 are arranged.

The halftone exposure device 42 comprises a fluorescent lamp 43 as a light source and an ND filter 44 arranged in front of the fluorescent lamp 43. As the light source of the exposure device 42, a halogen light source may be used in addition to the fluorescent lamp, and the halftone exposure device 42 irradiates the light emitted from the light source to the grayscale chart original document and reflects it. It is also possible to adopt a structure in which is exposed through a slit. In this halftone exposure device 42, the exposure amount is adjusted so that the surface potential after exposure becomes an intermediate level between the potential in the unexposed state and the potential in the completely exposed state. This is because defects such as "axis stripes" can be well detected when the surface potential is measured by performing exposure (hereinafter, abbreviated as intermediate exposure) corresponding to a halftone original. According to the experiment, when the halftone exposure device 42 has a structure in which the light emitted from the light source is applied to the gray scale chart original document and the reflected light is exposed through the slit, 0.2 to 0.5 gray is obtained. It is preferable to use a chart, and in particular, the 0.2 gray chart gives the largest defect signal. Further, as another embodiment of the halftone exposure device 42, a spot type exposure device 45 as shown by a virtual line in FIG. 11 may be used. Specifically, the beam diameter is several
A halogen light spot light device having a size of about mm or a semiconductor laser beam light device having a wavelength at which the inspected drum has an exposure sensitivity is preferable. These are commercially available and can be easily obtained. The spot type exposure device 45 is set at a position in the X direction equal to the measurement position of the micro electrometer S '. Then, the electrometer S ′ and the exposure device 45 scan the stage device in the X direction while maintaining the same positional relationship. Thereby, the exposure device 42 such as a fluorescent lamp is
In the case of, the exposure amount varies due to the unevenness of the light amount distribution in the X direction, but the light amount is always the same.
The exposure amount can be made uniform.

The detection signal of the minute surface electrometer S'is input to the defect signal extraction means E shown in FIG. The defect signal extraction means E is the constituent elements 31 to 3 of the first embodiment.
9, C1, C2, H1, H2, M1, M2 are composed of substantially the same components. However, in the first embodiment, since the line sensor S detects signals for two types of postures, the first detection posture and the second detection posture, the threshold memories M1 and M2 indicate the respective postures. Correspondingly, two types of threshold values were output respectively, but in the second embodiment, the inspection is performed with one type of posture. Therefore, in the second embodiment, one type of positive side threshold data T1i is stored in the threshold value memory M1 for one main scanning line, and one type of negative side threshold value is stored in the threshold value memory M2. The data T2i is stored for one main scanning line. As will be described later, the main scanning direction of the second embodiment is the arrow Y direction of FIGS. 11 and 13 (the circumferential direction of the surface of the photosensitive drum 1). Further, in the second embodiment, the threshold value selection signal A of the first embodiment is unnecessary and therefore omitted.

Next, the operation of the second embodiment of the surface layer defect detecting device of the present invention having the above-mentioned structure will be described. In the second embodiment, the scanning of the surface of the photosensitive drum 1 is the scanning in the arrow Y direction of FIG. 13 (scanning in the circumferential direction of the photosensitive drum 1) and the scanning in the arrow X direction (the photosensitive drum 1). (Scanning in the axial direction of 1) is the sub-scanning direction. That is, in the second embodiment, the main scanning is performed by the rotation of the photosensitive drum 1, and the minute surface electrometer S'is moved in the axial direction (X direction) of the photosensitive drum 1 to perform the sub scanning. The surface of the photosensitive drum 1 is spirally scanned. The scanning speed in this embodiment is about 60 Hz in the main scanning and 1 mm / in the sub-scanning.
It was about a second.

While the photosensitive drum 1 is rotated, its surface is uniformly charged by the charger 41. And
The halftone exposure device 42 performs halftone exposure on the uniformly charged surface of the photosensitive drum 1. The potential of the surface of the photosensitive drum 1 which has been subjected to the halftone exposure differs between the normal portion and the defective portion. Therefore,
The potential of the surface of the photosensitive drum 1 that has been subjected to the halftone exposure is
A defect in the photosensitive layer 3 on the surface of the photosensitive drum 1 can be detected by detecting with the minute surface electrometer S '.

The detection potential on the surface of the photosensitive drum 1 detected by the minute surface electrometer S'is processed by the defect signal extraction E in the same manner as in the first embodiment to extract a defect signal. That is, as for the detected surface potential obtained by scanning a predetermined portion of the surface of the photosensitive drum 1, the average value Va of the detected physical quantity average value calculating means E1 is calculated.
The calculated average value Va of the detected surface potentials is stored in the shift register 37 as the detected physical quantity average value storage means. The detected correction surface potential (Vi-Va) obtained by subtracting the average value Va of the detected surface potential from the detected surface potential Vi (i = 1, 2, ...) Obtained in the scan following the scan of the predetermined portion and the threshold memory. The thresholds T1i and T2i stored in M1 and M2 are the comparators (that is, defect detection signal output means) C1 and C2.
Are compared in. Similar to the first embodiment, the comparators C1 and C2 have a fixed value Vo for the detected correction surface potential (Vi-Va).
Value (Vi-Va + Vo) and the threshold memory M1, M
The threshold values T1i and T2i stored in 2 are compared, and the signal (Vi-
The defect detection signal "0" or "1" is output according to the positive or negative of Va + Vo-T1i) and Vi-Va + Vo-T2i).

Therefore, in the second embodiment as well, as in the first embodiment, the average value Va of the detection potentials at the respective portions of the photosensitive layer 3 on the surface of the photosensitive drum 1 is subtracted from the detection potential Vi. Value (Vi-Va) and the threshold value (Ti)
The defect will be detected by the signal corresponding to the difference.
Therefore, the average value (Va, m) of the detected potential in a part of the photosensitive layer 3 of the photosensitive drum 1 (for example, the m-th line part of the main scanning line) and another part (for example, the main scanning line). Even if there is a variation with the average value (Va, n) of the detected potential in the (n-th line portion), these variations can be compensated, so that the same threshold value T1i can be used to detect a defect. ..

It should be noted that variations in the detected potential at each portion of the surface of the photosensitive drum 1, that is, sensor output fluctuation, are
It is caused by the eccentricity of the photosensitive drum 1, the change in the distance from the measurement surface to the sensor surface due to the lack of parallelism with the surface of the photosensitive drum 1 when the minute surface electrometer S'is sub-scanned, and the like.

When detecting a defect, it is confirmed that a defect signal can be clearly obtained only at the time of intermediate exposure when three kinds of exposure amounts of an unexposed state, an intermediate exposure and a complete exposure state are given. did. This is considered to be due to the following reasons. Explaining defects of uneven film thickness such as “axis stripes” from the process of xerography, the surface of the photosensitive drum 1 is charged to −800 V as an initial charge, for example, and the laser is scanned by a reflection slit light of a document or a polygon mirror. In the process of forming a latent image by exposing with light, and developing, transferring, and obtaining a copy with a fixing device, a defective portion such as coating unevenness on the surface of the photosensitive drum 1 is a normal surface at the exposure level of a halftone original. The potential is about −300 V, but in the defective portion such as uneven film thickness, the functional defect of the charge transport layer of the photosensitive layer 3 becomes apparent and the surface potential shows a difference of about 100 V from the normal surface, and the difference in the density in terms of image quality. Appears as. On the other hand, in the unexposed state and the fully exposed state, which are initial charging, the difference in surface potential from the normal surface is small and no defect appears in the image quality.

Although the embodiment of the photosensitive layer failure detecting apparatus of the present invention has been described in detail above, the present invention is not limited to the above-mentioned embodiment, and deviates from the invention described in the claims. It is possible to make various small design changes without any need. For example, the photoconductor to which the present invention is applied is not limited to the photoconductor having a light-transmitting property applied on the mirror-finished metal drum shown in the embodiment, and a metal drum substrate for a laser printer is not used. Whether a surface-processed photoconductor drum, a photoconductor applied to a sheet-shaped substrate, not limited to a metal drum, or a non-translucent film, Since the body is uniform and mirror-like, it is possible to detect defects as well. Further, it is effective not only for the surface of the photoconductor but also for the defect inspection of the surface where the film is uniformly provided on the substrate.

[0072]

According to the present invention described above, the average value of the sensor input signal level is calculated by the detected physical quantity average value calculating means and the value of the sensor input signal level is corrected, so that the surface of the object to be inspected such as the photosensitive member drum is corrected. In the defect inspection described above, in the optical detection method, the defect signal can be correctly extracted by eliminating the influence of the fluctuation of the reflectance for each drum and the fluctuation of the light-receiving visual field due to the rotational eccentricity. Further, in the electrical detection method, it is possible to correctly extract the defect signal by eliminating the influence of the uneven charging and the sensor output fluctuation due to the distance fluctuation to the sensor surface of the point sensor.

[Brief description of drawings]

FIG. 1 is a schematic perspective view of a first embodiment of a surface layer defect detection device of the present invention.

FIG. 2 is a schematic plan view of the embodiment, showing a state in which the line sensor S is held in a first detection posture (a posture in which a light-receiving field of view is set at a boundary line portion of band-shaped light). Is.

FIG. 3 is a schematic plan view of the embodiment, showing a state in which the line sensor S is held in a second detection posture (the posture in which the light-receiving field of view is set at the center line portion of the band-shaped light). Is.

FIG. 4 is an explanatory diagram of a circuit portion of the embodiment, that is, a defect signal extracting means E.

FIG. 5 is an operation explanatory diagram when the line sensor S is in the first detection posture P1 in the same embodiment, and shows detection signals Vi, m, Vi, n of the m-th and n-th lines of each light receiving element Si. ,
The average value Va, m-1, of the detection signals of the m−1th and n−1th lines,
It is a figure which shows Va, n-1.

FIG. 6 is an operation explanatory diagram when the line sensor S is in the first detection posture P1 in the same embodiment, from the detection signals Vi, m, Vi, n of the m-th and n-th lines of each light receiving element Si. , The average value Va, m- of the detection signals of the (m-1) th and (n-1) th lines.
It is a figure which shows the value which subtracted 1, Va, n-1.

FIG. 7 is an operation explanatory view when the line sensor S is in the first detection posture P1 in the embodiment, and FIG.
Detection signals Vi, m of the m-th and n-th lines of each light receiving element Si,
A threshold value T1i and a value obtained by adding a constant value Vo to a value obtained by subtracting the average value Va, m-1, Va, n-1 of the detection signals of the m-1 and n-1 lines from Vi, n are shown. FIG. 6 is an explanatory diagram of signals compared by a comparator C1.

FIG. 8 is an explanatory view of the operation when the line sensor S is in the first detection posture P1 in the same embodiment, from the detection signals Vi, m, Vi, n of the m-th and n-th lines of each light receiving element Si. , The average value Va, m- of the detection signals of the (m-1) th and (n-1) th lines.
From the value obtained by adding a constant value Vo to the value obtained by subtracting 1, Va, n-1,
A defect detection signal obtained by shaping after subtracting the threshold value T1i,
That is, it is an explanatory diagram of the output signal of the comparator C1.

FIG. 9 is an operation explanatory view when the line sensor S is in the second detection posture P2 in the embodiment, and FIG.
Detection signals Vi, m of the m-th and n-th lines of each light receiving element Si,
A value obtained by adding a constant value Vo to a value obtained by subtracting the average value Va, m-1, Va, n-1 of the detection signals of the m-1 and n-1 lines from Vi, n, and threshold values T2i and T3i. In the figure, the comparators C1 and C2
FIG. 6 is an explanatory diagram of signals compared with each other.

FIG. 10 shows a line sensor S in the same embodiment.
In the first detection posture P1, the detection signals Vi, m, Vi, n of the m-th and n-th lines of each light receiving element Si are shown.
From the average value Va of the detection signals of the m-1 and n-1 lines,
The defect detection signal obtained by subtracting the threshold values T2i and T3i from the value obtained by adding the constant value Vo to the value obtained by subtracting m-1, Va, n-1, that is, the output signals of the comparators C1 and C2 FIG.

FIG. 11 is a schematic perspective view of a second embodiment of the surface layer defect detecting device of the present invention.

FIG. 12 is a schematic plan view of the second embodiment.

FIG. 13 is an explanatory diagram of a circuit portion of the second embodiment, that is, a defect signal extraction means E.

FIG. 14 is an explanatory diagram of a defect state of a surface layer (photosensitive layer) of a photoconductor (inspection object) and reflected light at the defective portion.

FIG. 15 is an explanatory diagram of a conventional threshold setting method of the surface layer defect detection apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Inspected object (photosensitive drum), 2 ... Base material, 3 ... Surface layer (photosensitive layer), 16 ... Fluorescent lamp, 18a ... Slit, 37 ...
Detected physical quantity average value storage means, 41 ... Charging device, 42 ... Halftone exposure device C1, C2 ... Defect detection signal output means (comparator), E1 ... Detected physical quantity average value calculation means, K ... Light irradiation device, M1, M2 …
Threshold value storage means, P1 ... First detection attitude, P2 ... Second detection attitude, S ... Line sensor, Si ... Light receiving element, S '... Micro surface electrometer, T1i, T2i, T3i ... Threshold value, U ... Line sensor support device , Va ... average value of detected physical quantity, Vi ... detected physical quantity,
Vi-Va ... Detection correction physical quantity, X ... Strip light (slit light)
Or the longitudinal direction of the line sensor S (direction in which a large number of light receiving elements Si are arranged), Y ... Optical axis direction of the line sensor, Z ... Relative movement direction of the surface of the DUT 1 and the line sensor S. ,

Claims (3)

[Claims] 1. A measurable physical quantity relating to the state of the surface of an object to be inspected having a base material and a surface layer formed on the surface thereof is scanned in a main scanning direction and a sub scanning direction orthogonal to the surface of the object to be inspected. However, in the surface layer defect detection device that is equipped with a physical quantity measuring device for detecting and detects surface layer defects by the detected physical quantity detected by this physical quantity measuring device, there is no defect that is configured almost the same as the inspected object to be inspected. Threshold value storage means for storing a threshold value set corresponding to the detected physical quantity of the surface of the object to be inspected, and detection physical quantity average value calculation means for calculating the average value of the detected physical quantity obtained by scanning a predetermined portion of the surface of the object to be inspected ,
Between the detected physical quantity average value storage means for storing the calculated detected physical quantity average value and the detected correction physical quantity obtained by subtracting the detected physical quantity average value from the detected physical quantity obtained in the scan subsequent to the scanning of the predetermined portion and the threshold value. A defect detection signal output means for outputting a defect detection signal corresponding to the difference, and a surface layer defect detection device. 2. The physical quantity is a light quantity, and the physical quantity measuring device comprises a light irradiating device for irradiating the surface of the object to be inspected with inspection light, and a reflection from the surface layer provided along the main scanning direction. A line sensor having a large number of light receiving elements for detecting the amount of light, and a moving device for relatively moving the line sensor and the surface of the object to be inspected in the sub-scanning direction, and the threshold value is set for each of the light receiving elements. A surface layer defect detection device characterized by the above. 3. The physical quantity is an electric potential, and the physical quantity measuring device performs halftone exposure with a charger for uniformly charging the surface of the object to be inspected and a light quantity about the same as the quantity of light reflected from a halftone original. Performing a halftone exposure device, a micro surface electrometer for measuring the potential of the surface of the object to be inspected, and relatively moving the micro surface electrometer and the surface of the object to be inspected in a main scanning direction and a sub scanning direction orthogonal to each other. A surface layer defect detection device, comprising: