JPH04169840A - Method and apparatus for inspecting flaw of circumferential surface - Google Patents

Abstract

PURPOSE:To make it possible to detect a flaw in the circumferential direction accurately in addition to the detection of a linear flaw and a dent in the parallel direction with a drum shaft by increasing the ratio between a main scanning period and the rotating period of a body under inspection in comparison with the ratio when a lateral linear flaw is detected. CONSTITUTION:For example, the circumferential length of a drum 3 of a light sensitive body 3 is made to be 250mm. When a main scanning period is made to be 1 millisecond under the state wherein the drum 3 is rotated by one rotation for 5 seconds, the surface of the drum is moved by about 50mum in the secondary scanning direction. When the period of the main scanning is made to be about 6 milliseconds, the surface of the drum 3 is moved by about 300mum during the main scanning period. Namely, when the starting point of the main scanning on the drum 3 is P and the terminating point of one main scanning is q2, the length of the Pq2 measured in the secondary scanning direction becomes about 300mum. Therefore, the scattered light signal caused by the flaw for 300mum in the secondary scanning direction is received in one main scanning, and the signals can be accumulated. In this way, the circumferential flaw can be accurately detected in addition to the detection of the linear flaw and the dent in parallel with the drum shaft.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to a method and apparatus for inspecting circumferential surface flaws, and particularly to surface flaws in a plane perpendicular to the rotational axis of an object to be inspected, that is, circumferential streaks. The present invention relates to a circumferential surface flaw inspection method and device that can detect flaws with high accuracy.

(Conventional technology) A specific example of the object to be inspected is a copying machine.

There are photoreceptor drums, fuser rolls, pressure rolls, etc. -C will be explained below using a photosensitive drum as an example, but is not limited to this.

Conventionally, a method shown in FIG. 7 has been adopted as a method for inspecting surface flaws on a photoreceptor drum.

A photosensitive drum 31 is irradiated with slit light 33 from a light projector 32. I! If the surface of the light drum 310 is not damaged,
The slit light 33 is specularly reflected on this surface, and the specularly reflected light 33
a and progresses. However, the photoreceptor drum 31
If there is a scratch on the surface of
l Proceed in different directions.

34 is a light receiver placed in a position that receives the scattered light 33b and does not receive the specularly reflected light 1, (3a).A line sensor is built into this light receiver, and the received scattered light is converted into electricity. The level of the signal output from the sensor 1'5 is low when there is no surface flaw, and becomes high when there is a surface flaw.Thereby, the presence or absence of surface flaws can be detected.

(Problems to be solved and attempted by the invention) Recent copying machines utilize a tram unit ridge type so that the user can replace the photoluminescent body and ram by himself/herself. . At the manufacturer, the tram unit rotates the drum, so there is a possibility of friction between the dust attached to the drum surface and the brushes that are in constant contact with the drum. Intervention t4-. t-, vertical streak-like scratches (hereinafter referred to as circumferential type and 11-f) may occur along the circumference of the drum.

Such circumferential shapes affect the normal image quality and appear in stretched images recorded on copy paper. For this reason, drums with circumferential molds must be rejected as defective products. Therefore, the surface inspection of the tram unit type photoreceptor drum is
In addition to inspecting the tram individually, inspection after the l/ram unit is assembled is also required.

By the way, in the table ■jj of the photoconductor tram 31, FIG.
As shown in a), there are line scratches 41 in the direction parallel to the drum axis, black scratches 43 such as dents with no directionality,
There is a circumferential type 45 as shown in b).

Black scratches 4 such as line scratches 41 and dents in the direction parallel to the drum axis
When the slit light 33 is irradiated to the first lens 3, scattered light 33b is generated in the direction explained in FIG. In addition, this scattered light 33
b is distributed in the circumferential direction of the photoreceptor tram 31.

On the other hand, when the circumferential mold 45 is irradiated with the Surino lt 33, the scattered light 33a' is reflected in the regular reflection direction 3 in FIG.
The soil 3a advances in approximately the same direction and is distributed in the axial direction of the Tokuko body drum 31.

Therefore, in the conventional surface flaw detection method, the line flaws 41 in the direction parallel to the drum axis and the point flaws 43 such as dents can be detected with high accuracy, but the scattered light from the circumferential mold 45 is small. There was a problem in that the light could not be detected accurately because it did not enter the light receiver 34.

In order to solve this problem, it is conceivable to arrange multiple false sensors in the light receiver 34, but this would increase the size of the device and require multiple systems of signal processing devices to process the output signals of the line sensors. Therefore, there was a problem that equipment costs increased.

The purpose of the present invention is to eliminate the problems of the conventional method described above,
It is an object of the present invention to provide a surface flaw inspection method and apparatus that can detect black flaws such as line flaws and dents in a direction parallel to the drum axis, as well as detect the circumferential flaws with high accuracy.

(Means and effects for resolving the division report) In order to achieve the above object, the invention of claim (1) provides a main scanning period determined by the reading period of the line sensor and a rotation speed of the object to be inspected. The feature is that the ratio between the two is larger than the ratio when horizontal line flaws are detected.

In general, horizontal line scratches are long in the main scanning direction but have a small width in the sub-scanning direction, whereas circumferential scratches have a small width in the main scanning direction and a continuous shape in the sub-scanning direction. In the line sensor, the accumulated amount of scattered light from the circumferential type is relatively large compared to the accumulated amount of scattered light from the horizontal line flaw.

As a result, information on circumferential flaws is emphasized, and circumferential flaws can be detected with high accuracy.

The invention according to claim (3) comprises a high-pass filter that receives the signal output of the line sensor as input, and a predetermined threshold value, and the signal output of the high-pass filter that exceeds the threshold value is determined by the circumference of the object to be inspected. The feature is that it is determined to be a circumferential flaw when it is detected continuously in the direction.

According to this invention, although the signal output of the circumferential flaw detected by the line sensor is small, the circumferential flaw information is emphasized by the high-pass filter, so that no circumferential flaw is missed.

As a result, circumferential flaws can be detected with high precision.

(Example) The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows a perspective view of an embodiment of the invention.

In the figure, 1 is a projector such as a halogen light, and 2 is a projector 1.
3 is a photoreceptor drum which is an object to be inspected; 4 is an optical system that collects the scattered light scattered by scratches on the surface of the photoreceptor drum 3; 5 is a line that receives the scattered light. It is a sensor. 5a is a pixel column of the line sensor 5, which is formed of, for example, 5000 pixels.

6 is a light-receiving field of view of the line sensor 5, and its width 6a is approximately 70 μm. The photosensitive drum 3 is rotated once in the direction of the arrow 7 at a constant speed in order to scan its entire surface.

As a result, sub-scanning is performed. On the other hand, the line sensor 5 scans the received information in the direction of arrow 8 and outputs it. This performs main scanning.

Regarding the sub-scanning and main scanning, conventionally, the sub-scanning was performed at a rate of rotating the photosensitive drum 3 once every 5 seconds, and the period of the main scanning was 1 msec. According to this conventional method, the line scratches 41 and black scratches 43 such as dents in the direction parallel to the drum axis could be detected with considerably high accuracy. However, the circumferential flaw 45 has not been detected accurately.

Therefore, in this embodiment, the main scanning speed is slowed down so that the main scanning period is, for example, 6 msec. the result,
The circumferential flaw can now be detected with high accuracy from the signal output of the line sensor 5.

The reason for this will be explained with reference to FIG. In the figure, 1
Reference numeral 1 indicates a circumferential scratch on the photoreceptor drum 3, 12 indicates a horizontal line scratch in a direction parallel to the drum axis, and the same reference numerals as in FIG. 1 indicate the same items as in FIG.

Now, if the circumference of the photoreceptor drum 3 is 250 cm, and the photoreceptor drum 3 is rotated once every 5 seconds, and the main scanning period is 1 msec as in the conventional method, this main scanning During the period, the surface of the photosensitive drum 3 moves about 50 μm in the sub-scanning direction.

For example, let the starting point of main scanning on the photoreceptor drum 3 be p,
If the end point of one main scan is qt, the length of pql measured in the sub-scanning direction is about 50 μm.

In contrast, in this embodiment, the main scanning period is approximately 6 msec.

If the main scanning period is about 6 msec, the surface of the photosensitive drum 3 will move about 300 μm in the sub-scanning direction during this main scanning period. That is, if the starting point of main scanning on the photosensitive drum 3 is p and the ending point of one main scanning is q2, the length of pq2 measured in the sub-scanning direction is about 300 μm.

Therefore, according to this embodiment, it is possible to receive and accumulate scattered light signals due to scratches of 300 μm in the sub-scanning direction in one main scan.

Here, focusing on the signal received by the pixel row 5a of the line sensor 5, the (n+1)th pixel has the circumferential scratch 11 as its field of view, and the '4n+3 and n+4th pixels have the horizontal line scratch 12 as its field of view. As in this example, if the main scanning period is slowed down,
As described above, since the moving distance in the sub-scanning direction becomes long, the scattered light from the circumferential scratch 11 continuously enters and accumulates in the n+1-th pixel every main scanning period, whereas The scattered light from the horizontal line scratches 12 does not enter the n+3rd and n+4th pixels continuously. Therefore, the amount of scattered light from the circumferential ulcer 11 that is incident on the n+1th pixel and accumulated is the amount that the scattered light from the horizontal line gi and the amount of scattered light from the circumferential tumor 12 are
+3, n + The ratio becomes relatively large compared to the amount of light incident on the fourth pixel and accumulated.

Therefore, the circumferential scratch 11 output from the line sensor 5
The signal output for the horizontal line flaw 12 is relatively larger than the signal output for the horizontal line flaw 12, and is emphasized.

FIG. 3 shows a flowchart of a photosensitive drum flaw inspection method employing the surface flaw inspection method according to this embodiment.

In step S1, the rotational speed of one rotation of the photosensitive drum is set to 5 seconds 17, and the main scanning period is set to 1 msec. In step S2, the line sensor detects the scattered η light from the photoreceptor drum surface at a main scanning period of 1 msec.
Detects horizontal line scratches, black scratches, etc. In step S3, it is determined whether the photoreceptor drum has rotated one rotation (7 degrees or not.) According to the affirmative answer in step S3, the entire surface of the photoreceptor drum has been inspected for horizontal line scratches, -scratches, etc. , proceed to the next step.

In step S4, the main scanning period is set to 6 msec. Then, the photosensitive drum is rotated at the same speed as above. In step S5, the circumferential flaw 11 is detected. In step S6, it is determined whether the photoreceptor drum has rotated 1/3 of a revolution or not, and if this determination is affirmative, a series of flaw inspection processes is completed.

In this flowchart, the detection of the circumferential flaw 11 is completed after the photoreceptor drum has been rotated 173 times, but since circumferential flaws normally extend over the entire circumference of the photoreceptor drum,
A test of 3 rotations is sufficient. Thereby, the inspection time for flaw determination can be shortened. Note that the specific times in the flowchart are merely examples, and the present invention is not limited thereto.

In the embodiment described above, the main scanning period is lengthened, but the sub-scanning speed may be increased at the same time as the main scanning period is lengthened. In this way, the circumferential flaw is further emphasized and the inspection time can be shortened. Alternatively, the main scanning period may be constant (for example, 1 msec) and only the sub-scanning period may be changed.

Next, a second embodiment of the present invention will be described with reference to FIG. 4. FIG. 4 shows a block diagram of the embodiment.

In the figure, 5 is a line sensor, 15 is a line sensor 5
A high-pass filter whose input is the output of , 16 is a threshold, 1
7 is a comparator, and 18 is a display that displays the output of the comparator 17. In this example, the width of the circumferential scratch is at its maximum, () 3
Since it was a normal level, a 1 Ipasu filter with a 3QQKHz culmness was used.

The line sensor 5 outputs an output signal of the scattered light received by the method shown in FIG. The waveform of this 1-power signal is as shown in C in Figure 5. C1 indicates the signal output of a horizontal line flaw, and C2 indicates the signal output of a circumferential flaw.1゜The method shown in Figure 3 - The method of determining flaws using the output signal of the received scattered light takes into account the unevenness of the light intensity distribution as in the conventional method. However, in this embodiment, the light intensity distribution (, which is affected by -5 is the first, and in order to extract the -circle 1'.') The output signal of the filter 5 is input to the high-pass filter 15.

The output signal waveform of the high-pass filter 15 becomes a signal in which the flawed portion is extracted, as shown in FIG. 5A. Therefore, the threshold value 16 is set to a constant value 17 as shown in b in the figure, and the signal a and the threshold value S are compared by a comparator 17. Then, the output is displayed on the display 18.

According to this embodiment, since the output signal of the line sensor 5 is filtered through the No. 1 bus filter 15 (J through A), information on the width of the scratch is lost. Instead of making a determination, the determination can be made based on whether G exists continuously in the circumferential direction, so the accuracy of detecting circumferential flaws can be increased by one.

Next, a third embodiment of the present invention will be described with reference to FIG. In the figure, 20 indicates a light receiver, and the same reference numerals as in FIG. 1 indicate the same parts as in FIG.

In this embodiment, the slit light 2 emitted from the floodlight 1 is
The focal point 2a of the light emitter tram 3 is placed at a position approximately 5 cities away from the surface of the light emitter tram 3). Mano Photoreceptor Drano,
3. Leg/Front C.) Specular reflection direction 21) of the slit light irradiation section 21), 1 is a position that is off H3, and the optical axis 23 is placed at the peripheral part of the slit light irradiation section 21 described in 0.1. The light receiver 20 is placed at.

In this example, although the reason is not clear due to the inventor's experiment,
It was found that the scattered light from the circumferential flaws was incident on the line sensor of the light receiver 20 well, and the detection accuracy of the circumferential flaws was improved.

In order to realize the apparatus of this embodiment, it is only necessary to slightly move the light projector 1 and the light receiver 20 from the conventional arrangement of the optical device for detecting surface flaws, and the apparatus can be easily realized.

Furthermore, when this embodiment and the first embodiment are combined,
Circumferential flaws can be detected with higher accuracy.

The method for detecting circumferential scratches according to the present invention is not limited to photosensitive drums, but can also be used to detect circumferential tin on cylindrical metal rolls such as fuser rolls and pressure rolls.

(Effects of the Invention) As is clear from the above description, according to the present invention, the circumferential flaw information output from the line sensor is relatively emphasized compared to other flaw information. can be detected with high accuracy.

As a result, the accuracy of determining whether the inspected object is good or defective can be improved.

[Brief explanation of drawings]

Fig. 1 is a schematic perspective view of an embodiment of the present invention, Fig. 2 is an enlarged view of its main parts, Fig. 3 is a flowchart for explaining the operation of this embodiment, and Fig. 4 is a schematic perspective view of an embodiment of the present invention. FIG. 5 is a block diagram of the second embodiment, FIG. 5 is a waveform diagram of the main part of the signal, FIG. 6 is a schematic diagram of the third embodiment of the present invention, FIG. 7 is a schematic diagram of the conventional GT position, and FIG. 8 is a schematic diagram of the conventional GT position. FIG. 3 is an explanatory diagram of the traveling direction of scattered light due to scratches. DESCRIPTION OF SYMBOLS 1... Floodlight, 3... Photoreceptor drum, 5... Line sensor, 11... Circumferential scratch, 12... - Horizontal line scratch, 15
...High-pass filter, 20... Light receiver. Agent: Patent attorney Michito Hiraki and 1 other person Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) By rotating the object to be inspected around its axis, projecting light extending in the axial direction onto the surface of the object, and receiving the scattered light from the surface with a line sensor, damage to the surface of the object to be inspected is detected. A surface flaw inspection method for detecting surface flaws, characterized in that the ratio between the main scanning period determined by the readout period of a line sensor and the rotation period of the object to be inspected is larger than the ratio when detecting horizontal line flaws. Circumferential surface flaw inspection method. (2) By rotating the object to be inspected around its axis, projecting light extending in the axial direction onto the surface of the object, and receiving the scattered light from the surface with a line sensor, the scratches on the surface of the object to be inspected are removed. A surface flaw inspection method for detecting surface flaws, wherein the surface of the object to be inspected is irradiated with light extending in the axial direction in an out-of-focus state, and the line sensor receives scattered light from the periphery of the light. A circumferential surface flaw inspection method characterized by: (3) By rotating the object to be inspected around its axis, projecting light extending in the axial direction onto the surface of the object, and receiving the scattered light from the surface with a line sensor, damage to the surface of the object to be inspected is detected. A surface flaw inspection device for detecting surface flaws, comprising a high-pass filter that receives the signal output of the line sensor as input, and a predetermined threshold value, and the signal output of the high-pass filter that exceeds the threshold value is detected in the circumferential direction of the object to be inspected. A circumferential surface flaw inspection device characterized in that a circumferential surface flaw is determined to be a circumferential flaw when continuously detected.