JP2002168611A - Method and device for inspecting cylindrical object to be inspected for surface ruggedness - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and device by which a cylindrical object to be inspected, such as photosensitive drum, etc., can be inspected for surface flaws with high sensitivity. SOLUTION: The cylindrical object 1 to be inspected is scanned with a spot light 2, by moving the light 2 at a uniform velocity in the axial direction of the object 1, and the reflected light from the object 1 is received by means of a linear light-receiving element 3. The scanning clock of the element 3 is set equally to the scanning speed of the light 2. Since the light 2 is positioned, so that the reflected light lies in side of the visual field 4 of the element 3, the received light quantity becomes larger. However, when the height of the object 1 is changed, a spot light 2' goes out of the visual field 4 and the received light quantity decreases. Therefore, scanning is performed by rotating the object 1, so that the whole surface of the object 1 is irradiated with the spot light 2. Since the received light quantity decreases at a spot where the surface ruggedness of the object 1 changes, the object 1 can be inspected for surface ruggedness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the detection of surface defects of a cylindrical test object, and more particularly, to the detection of bulges and irregularities of ridges substantially parallel to the direction of a cylindrical axis, and three-dimensional measurement. The present invention relates to a method and an apparatus.

[0002]

2. Description of the Related Art A conventional defect inspection method for a cylindrical test object such as a photosensitive drum for an image forming apparatus is disclosed in Japanese Patent Application Laid-Open No. 2-201142 or 4-169840. There is one shown in Japanese Patent Publication No.

FIG. 1 is a perspective view showing a method disclosed in Japanese Patent Application Laid-Open No. Hei 2-201142. In the figure, a laser light beam 32 from a light source 31 is irradiated via a rotary polygon mirror 36 so as to scan in the axial direction of a photosensitive drum 33. The scanning light is reflected on the photosensitive layer surface of the drum 30, and the reflected light from the normal surface almost enters the light receiver 35, the intensity of the reflected light is detected, and the output is sent to a predetermined arithmetic processing unit or the like. Is entered. In this process, when the detection value drops abnormally, it is detected as an abnormality in the surface state.

FIG. 2 is a diagram showing a method disclosed in Japanese Patent Application Laid-Open No. 4-169840. In the figure, a slit light 42 is projected from a light projector 41 having a halogen light source and the like toward a photosensitive drum 43. The scattered light scattered by the surface defect of the photoconductor drum 43 is collected by the lens 44 and received by the line sensor 45. The line sensor 45 has a pixel row, and its light receiving range is a range indicated by 431 on the surface of the photosensitive drum 43. Here, abnormalities in scattered light due to defects are detected.

A variety of defects such as pinholes, dents, abrasions, entrapment of air bubbles, cracks, dust and the like, irregularities in the thickness of the photosensitive layer, liquid dripping, and scratches on the support are all present on the photosensitive drum. May occur. In the case of the conventional optical inspection device as described above, a high detection power is exhibited for a defect having a large rate of change in surface unevenness, such as a defect due to adhesion of pinholes, dents, abrasions, dust and the like. However, there is a problem in detection accuracy for a defect having a small rate of change in unevenness, such as unevenness in the thickness of the photosensitive layer, or a defect having no change in unevenness on the surface of the photosensitive member, such as a scratch on a support. is there.

In view of the above problems in the conventional defect inspection of a cylindrical test object, the present invention provides a method and an apparatus capable of detecting irregularities on a cylindrical test object such as a photosensitive drum with high sensitivity. With the goal.

[0007]

According to a first aspect of the present invention, there is provided a method for inspecting the surface unevenness of a cylindrical object, wherein the cylindrical object is rotated while rotating the cylindrical object. The spot light is scanned on the ridge line of the inspection object, and light is received while synchronizing with the spot light scanning using a line type light receiving element in which pixels are arranged in the same direction as the spot light scanning direction. The surface unevenness of the cylindrical test object is detected from a decrease in the amount of light received at each pixel.

According to a second aspect of the present invention, in order to achieve the above object, the method for inspecting the surface unevenness of a cylindrical object according to the first aspect of the present invention comprises the steps of:
The scanning is performed by a scanning optical system including a polygon mirror and an fθ lens.

According to a third aspect of the present invention, in order to achieve the above object, in the inspection method of the first aspect, the spot light scanning is performed by an LED array. And

According to a fourth aspect of the present invention, in order to achieve the above object, the method of inspecting the surface unevenness of a cylindrical object is the same as the inspection method of any one of the first to third aspects, wherein the viewing direction of the line type light receiving element is changed. The imaging is performed a plurality of times by changing the direction, and the viewing direction in which the amount of received light is maximized is specified for each pixel, and the direction of the unevenness of the cylindrical test object and the amount thereof are determined from the direction.

According to a fifth aspect of the present invention, there is provided a method for inspecting the surface unevenness of a cylindrical test object, wherein the irradiation position of the spot light is changed in the inspection method according to any one of the first to third aspects. The imaging position is determined a plurality of times, the irradiation position at which the amount of received light is maximized is specified for each pixel, and the unevenness direction and the amount of the cylindrical test object are determined from the irradiation position.

According to a sixth aspect of the present invention, in order to achieve the above object, the method for inspecting the surface unevenness of a cylindrical object according to any one of the first to third aspects, comprises: The imaging is performed a plurality of times by changing the height, the height at which the amount of received light is maximized is specified for each pixel, and the unevenness direction and the amount of the cylindrical test object are determined from the height. .

According to a seventh aspect of the present invention, in order to achieve the above object, the method for inspecting the surface unevenness of a cylindrical test object according to any one of the first to third aspects, comprises the steps of: A plurality of images are taken by changing the height of the scanning optical system and the entire light receiving optical system for receiving light, and the height at which the amount of received light is maximized is specified for each pixel, and the cylindrical test object is determined from the height. It is characterized in that the direction of the unevenness of the object and the amount thereof are determined.

According to an eighth aspect of the present invention, in order to achieve the above object, the method for inspecting the surface unevenness of a cylindrical test object uses a confocal optical system in any one of the first to seventh aspects. Features.

According to a ninth aspect of the present invention, there is provided an apparatus for inspecting the surface unevenness of a cylindrical test object, comprising: means for rotating the cylindrical test object; Means for scanning the spot light, means for receiving light while synchronizing with the spot light scanning using a line type light receiving element in which pixels are arranged in the same direction as the spot light scanning direction, and each pixel of the line type light receiving element And means for detecting the surface irregularities of the cylindrical test object from the decrease in the amount of received light.

According to a tenth aspect of the present invention, in order to achieve the above object, the inspection apparatus according to the ninth aspect has the following features.
Means for changing the irradiation position of the spot light, the height of the cylindrical test object or the entire height of the scanning optical system for scanning the spot light and the entire light receiving optical system for light reception, Imaging is performed, and the detecting means specifies a visual field direction in which the amount of received light is maximized for each pixel, and determines the uneven direction and the amount of the cylindrical test object from the direction.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a perspective view showing the first embodiment of the present invention. As shown in the drawing, the spot light 2 is scanned at a constant speed along the axial direction of the cylindrical test object 1, and the reflected light is received by the line type light receiving element 3. At this time, the scanning cycle of the line type light receiving element 3 is set to be the same as the scanning speed of the spot light 2 (see FIG. 4). As a result, as shown in FIG. 5, in the case of the cylindrical specimen 1, the amount of received light is large because the position of the spot light 2 is inside the visual field 4 of the line-type light receiving element 3. However, the height changes and the cylindrical test object 1 '
In this case, the amount of received light decreases because the spot light 2 ′ is outside the visual field 4. Therefore, the spot light 2 is scanned over the entire surface by rotating the cylindrical test object 1. As a result, as shown in FIG. 6, the amount of received light is reduced where the irregularity of the cylindrical test object 1 changes, so that the irregularity test of the cylindrical test object 1 can be performed. Further, according to this method, not only the detection of the surface unevenness but also the defect which does not have the unevenness such as the shading unevenness but differs only in the reflectance can be detected from the difference in the amount of received light.

FIG. 7 is a perspective view showing a second embodiment of the present invention. In order to scan the spot light 2 at a constant speed, a laser light source 5, a polygon scanner 6, and an fθ lens 7 are used as shown. Then, the reflected light is condensed by the imaging lens 8 and received by the CCD line sensor 9, whereby the first
The inspection method according to the embodiment is realized. The scanning speed of the CCD line sensor 9 and the rotation speed of the polygon scanner 6 are adjusted to synchronize the spot light 2 and the scanning speed of the CCD line sensor 9.

FIG. 8 is a perspective view showing a third embodiment of the present invention. As shown, the spot light 2 is scanned at a constant speed using the LED array 10. The reflected light is condensed by the imaging lens 8 and received by the CCD line sensor 9, thereby realizing the inspection method of the first embodiment. The scanning clock of the CCD line sensor 9 and the lighting frequency of the LED array 10 are adjusted to synchronize the spot light 2 and the scanning speed of the CCD line sensor 9.

FIG. 9 is a perspective view showing a fourth embodiment of the present invention. In the inspection methods of the first to third embodiments,
Even if the presence or absence of the unevenness of the cylindrical test object 1 is known, the unevenness cannot be distinguished. Therefore, as shown in FIG. 9, the image is taken a plurality of times by changing the position of the line type light receiving element 3. First, when the first imaging is performed with the line-type light receiving element at the position 3, the amount of received light is large only when the cylindrical test object is at the height of 1. Next, when the second imaging is performed with the line-type light receiving element at the position 3 ', the amount of received light is large only when the cylindrical test object is at the height of 1'. In addition, 3 "line type photo detector
When the third imaging is performed at the position, the amount of received light is large only when the cylindrical test object is at a height of 1 ″. The imaging is repeated a predetermined number of times as described above, and each pixel is scanned as shown in FIG. The number of times of imaging at which the amount of received light is maximized is calculated for each time, and as a result, the unevenness of the cylindrical test object 1 can be determined, that is, FIG.
In the case of the embodiment, if the amount of light received by the line-type light receiving element 3 'is the maximum, it can be determined that the height of the cylindrical test object is the height indicated by reference numeral 1' in the figure. FIG. 16 shows the flow of signal processing.
Shown in

The configuration of the device according to the present embodiment is as follows.
Constant-speed scanning of the spot light 2 by the polygon scanner 6 shown in FIG. 7 or the LED array 10 shown in FIG.
In the light reception by the CCD line sensor 9, the field of view of the CCD line sensor 9 may be changed (a mechanism for changing the view is not shown, but a known mechanism may be used as appropriate), and the imaging may be repeated a plurality of times.

FIG. 10 is a perspective view showing a fifth embodiment of the present invention, and shows another method capable of judging unevenness similarly to the embodiment of FIG. As shown in the drawing, imaging is performed a plurality of times by changing the irradiation position of the spot light 2. First, when the irradiation position of the spotlight is set to 2 and the first imaging is performed, the cylindrical test object becomes 1
The received light amount is large only when the height is Next, when the second imaging is performed with the irradiation position of the spot light set to 2 ′, the received light amount is large only when the cylindrical test object is at the height of 1 ′.
In this manner, the imaging is repeated a predetermined number of times, and the number of times of imaging that maximizes the amount of received light is calculated for each pixel as shown in FIG. The unevenness of the cylindrical test object 1 is determined from the result. The flow of the signal processing is the same as in FIG.

As a method and an apparatus for changing the irradiation position of the spot light 2, a method of changing the angle by placing a reflecting mirror 11 in the optical path as shown in FIG.
As shown in (1), a method of changing the angle of the entire light source unit 12 can be considered.

Another method capable of determining the unevenness of the cylindrical test object as in the embodiment of FIG. 9 will be described. Cylindrical test object 1
The imaging is performed a plurality of times by changing the height of the cylindrical object 1. First, the cylindrical object 1 is set to a certain height to perform the first imaging, and then the height is changed a predetermined number of times to perform the imaging. Search for the height that maximizes the amount of received light. The unevenness of the cylindrical test object 1 is determined from the result. The flow of the signal processing is the same as in FIG.

It should be noted that instead of changing the height of the cylindrical test object 1, imaging may be performed a plurality of times by changing the height of the entire optical system.

FIG. 13 shows a method for improving the detection sensitivity by configuring a confocal optical system in the above embodiment. That is, as shown in FIG. 13, the light from the light source unit 12 is condensed on the cylindrical test object 1 using the lens 13, and the reflected light is condensed using the imaging lens 14, and the image is formed. A pinhole 15 is arranged at the position, and light is received by the line type light receiving element 3 placed behind. In this case, if the height of the cylindrical test object 1 changes (in FIG. 13, if it changes in the horizontal direction on the paper surface), the reflection spot deviates from the image forming position, and as a result, it cannot pass through the pinhole 15, and No light can be received. That is, a characteristic of the confocal optical system is that the amount of received light sharply increases only when the cylindrical test object 1 is at a predetermined height.

FIG. 1 shows a specific configuration example of a confocal optical system.
It is shown in FIG. In the illustrated example, an imaging lens 14 is provided for each element of the line type light receiving element 3, a pinhole 15 is placed at the image forming position, and the line type light receiving element 3 is arranged immediately after. Of course, other configurations may be used. By using the device having this configuration, it is possible to detect the unevenness of the cylindrical test object 1 with higher sensitivity.

In the above embodiment, instead of changing the height of the cylindrical test object 1, the height of the entire optical system may be changed.

[0029]

According to the first aspect of the present invention, the method for inspecting the unevenness of the surface of a cylindrical test object is achieved by synchronizing the spot light scanning with the scanning speed of the line type light receiving element. There is an effect that irregularities of an object can be detected with high sensitivity.

According to a second aspect of the present invention, as described above, the scanning optical system including the laser light source, the polygon mirror, and the fθ mirror,
The use of the D-line sensor has an effect that it is possible to synchronize the spot light scanning with the light receiving element in addition to the effect common to the method of the first aspect.

According to a third aspect of the present invention, as described above, the method for inspecting the surface unevenness of a cylindrical object uses the scanning optical system composed of the LED array and the CCD line sensor to realize the method of the first aspect. In addition to the common effect, there is an effect that it is possible to synchronize the spot light scanning with the light receiving element.

In the method for inspecting the surface unevenness of a cylindrical object according to a fourth aspect, as described above, imaging is performed a plurality of times while changing the viewing direction of the line type light receiving element, and the amount of light received for each pixel is reduced. By specifying the direction of the visual field which is maximized, in addition to the effects common to the methods of claims 1 to 3, there is an effect that it is possible to determine the uneven direction of the cylindrical test object.

In the method for inspecting the surface unevenness of a cylindrical test object according to the fifth aspect, as described above, imaging is performed a plurality of times while changing the irradiation position of the spot light, and the amount of received light is maximized for each pixel. By specifying such an irradiation position, in addition to the effects common to the methods of claims 1 to 3, there is an effect that it is possible to determine the uneven direction of the cylindrical test object.

In the method for inspecting the surface unevenness of a cylindrical object according to a sixth aspect, as described above, imaging is performed a plurality of times while changing the height of the cylindrical object, and the amount of received light is determined for each pixel. By specifying the height at which is maximized, in addition to the effects common to the methods of claims 1 to 3, there is an effect that it is possible to determine the uneven direction of the cylindrical test object.

According to a seventh aspect of the present invention, in the method for inspecting the surface unevenness of a cylindrical test object, as described above, the imaging is performed a plurality of times by changing the height of the entire scanning optical system and the light receiving optical system, By specifying the height at which the amount of received light is maximized, in addition to the effects common to the methods of claims 1 to 3, there is an effect that it is possible to determine the uneven direction of the cylindrical test object.

According to the eighth aspect of the present invention, as described above, the method for inspecting the unevenness of the surface of the cylindrical test object has the same effects as those of the first to seventh aspects by configuring the confocal optical system. In addition, there is an effect that unevenness of a cylindrical test object can be detected with high sensitivity.

According to a ninth aspect of the present invention, as described above, the apparatus for inspecting the unevenness of the surface of a cylindrical object performs imaging a plurality of times while changing the height of the cylindrical object, and receives the amount of received light for each pixel. By specifying the height at which is maximized, it is possible to determine the uneven direction of the cylindrical test object.

According to the tenth aspect of the present invention, as described above, the apparatus for inspecting the surface unevenness of a cylindrical object performs imaging a plurality of times by changing the heights of the scanning optical system and the light receiving optical system as a whole, and performs each pixel. By specifying the height at which the amount of received light is maximized,
In addition to the same effects as the device according to claim 9, there is an effect that it is possible to determine the uneven direction of the cylindrical test object.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a conventional method for inspecting the surface unevenness of a cylindrical test object.

FIG. 2 is a perspective view showing another example of the conventional method for inspecting the surface unevenness of a cylindrical test object.

FIG. 3 is a perspective view showing the first embodiment of the present invention.

FIG. 4 is a diagram illustrating a relationship between a scan clock and a scan speed in the embodiment of the present invention.

FIG. 5 is a perspective view for explaining a change in the height of the cylindrical test object and a change in the amount of received light.

FIG. 6 is a diagram for explaining a change in unevenness and a change in a received light amount of a cylindrical test object.

FIG. 7 is a perspective view showing a second embodiment of the present invention.

FIG. 8 is a perspective view showing a third embodiment of the present invention.

FIG. 9 is a perspective view showing a fourth embodiment of the present invention.

FIG. 10 is a perspective view showing a fifth embodiment of the present invention.

FIG. 11 is a perspective view showing a method and an apparatus for changing the irradiation position of the spot light.

FIG. 12 is a perspective view showing another method and apparatus for changing the irradiation position of the spot light.

FIG. 13 is a conceptual diagram showing a configuration of a confocal optical system.

FIG. 14 is a diagram illustrating a specific configuration example of a confocal optical system.

FIG. 15 is a diagram illustrating an example of a change in the amount of received light in one pixel during multiple scanning.

FIG. 16 is a flowchart of an operation in the embodiment of the present invention.

[Explanation of symbols]

 1, 1 ', 1 "cylindrical test object 2, 2' spot light 3, 3 ', 3" line type light receiving element 4 field of view of line type light receiving element 5 laser light source 6 polygon scanner 7 fθ lens 8 imaging lens 9 CCD line sensor 10 LED array 11 Reflecting mirror 12 Light source unit 13 Lens 14 Imaging lens 15 Pinhole

Continued on the front page F-term (reference) 2F065 AA49 BB08 FF01 FF04 GG04 GG14 HH04 JJ02 JJ25 LL15 MM26 MM28 2G051 AA90 AB07 BA10 BA20 BB09 BB11 BC01 BC06 CA03 CB01 CC07 CD01 CD02 2H035 CA07 CB01 CB02 2

Claims (10)

[Claims] 1. A line type light receiving element in which pixels are arranged in the same direction as the spot light scanning direction by scanning a spot light on a ridge line of the cylindrical object while rotating the cylindrical object. To receive light while synchronizing with the spot light scanning,
A method for inspecting the surface unevenness of a cylindrical test object, wherein the surface unevenness of the cylindrical test object is detected from a decrease in the amount of light received at each pixel of the line type light receiving element. 2. A method according to claim 1, wherein said spot light scanning is performed by a scanning optical system comprising a laser light source, a polygon mirror and an fθ lens. 3. The method according to claim 1, wherein the spot light scanning is performed by an LED array. 4. A plurality of images are taken by changing the viewing direction of the line-type light receiving element, a viewing direction in which the amount of received light is maximized for each pixel is specified, and the uneven direction of the cylindrical object is determined from the direction. 4. The method for inspecting the surface unevenness of a cylindrical test object according to claim 1, wherein the amount is determined. 5. An image pickup operation is performed a plurality of times while changing the irradiation position of the spot light, an irradiation position at which the amount of received light is maximized is specified for each pixel, and the projection and depression directions of the cylindrical test object are determined from the irradiation position. 4. The method according to claim 1, wherein the amount is determined. 6. A plurality of images are taken by changing the height of the cylindrical test object, a height at which the amount of received light is maximized is specified for each pixel, and the height of the cylindrical test object is determined from the height. 4. The method for inspecting the surface unevenness of a cylindrical test object according to claim 1, wherein the direction and the amount of the unevenness are determined. 7. A scanning optical system for scanning the spot light and a light receiving optical system for receiving light are changed in height to perform image pickup a plurality of times, and a height at which the amount of received light is maximized for each pixel. 4. The method according to claim 1, further comprising: determining an uneven direction of the cylindrical test object and an amount thereof based on the height.
Inspection method for surface unevenness of any one of the cylindrical specimens. 8. The method according to claim 1, wherein a confocal optical system is used. 9. A means for rotating a cylindrical test object, a means for scanning a spot light on a ridge line of the cylindrical test object,
Means for receiving light while synchronizing with the spot light scanning using a line type light receiving element in which pixels are arranged in the same direction as the spot light scanning direction; and Means for detecting surface irregularities of a cylindrical test object. 10. A scanning optical system for scanning the field direction of the line type light receiving element, the irradiation position of the spot light, the height of the cylindrical test object or the spot light, and the light receiving optical system for the light reception. It has a means for changing the height of the entire system, performs imaging a plurality of times, and the detecting means specifies a viewing direction in which the amount of received light is maximized for each pixel, and from that direction, the unevenness of the cylindrical test object is determined. The apparatus for inspecting the surface unevenness of a cylindrical test object according to claim 9, wherein the direction and the amount thereof are determined.