JP2008070164A - Roller testing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a roller testing method capable of objectively grasping roughness of a circumferential surface of a roller which is made of a porous elastic body, improving efficiency of a quality judging work and suppressing variations in quality judgements. <P>SOLUTION: A contour of the circumferential surface of a roller main body is detected from a projection image of the roller, and coordinates of a plurality of pixels making up the contour are acquired. Then, distances between a base line which is parallel to the center axis of the roller, and the plurality of pixels, are obtained. Next, a variance is obtained from respective distance values. The above distance variance corresponds to the roughness of the circumferential surface of the roller main body well. Therefore, the roughness of the circumferential surface of the roller main body can be determined objectively from the distance variance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a roller inspection method for determining the roughness of the outer peripheral surface of a roller made of a porous elastic body.

  2. Description of the Related Art Conventionally, for example, in an electrophotographic printer or copying machine, an electrostatic latent image using a potential difference is formed on a photosensitive drum, and this electrostatic latent image is reversely developed by a developing device and visualized as a toner image. Next, the toner image is transferred from the photosensitive drum onto the transfer paper by the transfer drum. In this developing device, toner in the hopper or toner cartridge is supplied to the developing roller by the toner supply roller, and further supplied from the developing roller to the photosensitive drum. The toner supply roller has a configuration in which a roller body made of, for example, polyurethane foam is supported on a cored bar. The toner supply roller is required to have a function of forming a toner film having a uniform density on the surface of the developing roller.

  Such a toner supply roller is generally manufactured as follows. That is, when forming a roller main body from slab foaming urethane, first, a prism or a round bar is cut out, and both are integrated through a cored bar in a hole opened in these. Next, the outer peripheral surface of a prism or a round bar is ground into a columnar shape while rotating around a cored bar. Also, when forming a roller body using a foamed urethane foam, the cored bar is set in the mold and molded integrally, or a molded product in which a hole into which the cored bar is inserted is formed by the mold. A cored bar is inserted and bonded, or a hole is made later in the molded body formed into a solid bar shape, and the cored bar is inserted and bonded. Next, the outer peripheral surface of the roller body is ground into a cylindrical shape in the same manner as the roller using the slab foaming urethane. However, fluffy protrusions are often formed on the outer peripheral surface of the roller body of the roller thus manufactured. This protrusion prevents the toner from being uniformly supplied to the surface of the developing roller as the number of protrusions is particularly high, and decreases the recording quality of the image on the recording paper. Therefore, conventionally, when manufacturing the toner supply roller, the operator visually confirms the formation state of the protrusion on the outer peripheral surface of the roller body, that is, the roughness of the outer peripheral surface of the roller main body, and determines whether the product is good or bad. Work was being done. In this inspection, basically, a toner supply roller on which many high protrusions are formed is selected as a defective product. However, in the inspection visually performed by the worker, not only the work efficiency is bad, but it is also unavoidable that a difference in the judgment of pass / fail is generated among the workers. Accordingly, in order to keep the quality of the entire product above a certain level, the criteria for judgment are made strict, and even if there is a difference in judgment, the quality must be kept below a certain level.

As a method for inspecting the surface of a non-inspection object, for example, there is one disclosed in Patent Document 1. This inspection method detects the presence or absence of uneven defects on the dome-shaped surface of the inspection object.
Japanese Patent Laid-Open No. 11-160046

  By the way, the roller body of the toner supply roller is inspected for the degree of roughness of the outer peripheral surface corresponding to the formation state of the protrusion. On the other hand, the inspection method disclosed in Patent Document 1 detects the presence or absence of uneven defects on the surface of the inspection object, and does not determine the degree of roughness. Therefore, the inspection method of Patent Document 1 cannot be used for the inspection of the roughness of the outer peripheral surface of the toner supply roller.

  An object of the present invention is to objectively grasp the roughness of the outer peripheral surface of a roller made of a porous elastic body. As a result, it is possible to improve the efficiency of quality judgment work and to suppress variations in quality judgment. An object of the present invention is to provide a roller inspection method.

  In order to achieve the above object, the invention described in claim 1 is a roller inspection method for inspecting the roughness of the outer peripheral surface of a roller made of a porous elastic body. Distance between the plurality of pixels and the reference line set in parallel to the central axis of the roller by detecting the contour line of the outer peripheral surface and grasping the coordinates of the plurality of pixels constituting the contour line Each of the distances is obtained, a variance of each distance value is obtained, and the roughness of the outer peripheral surface of the roller is determined based on the magnitude of the variance. Here, “dispersion” is the same as the definition used in statistics, and is a value obtained by the following procedure. First, the distance from the reference line of the pixels constituting the contour line is obtained, and the average value of each distance is obtained. Next, for each distance, a deviation between the distance and the average value is obtained, and a value obtained by squaring the deviation is obtained. Next, all the square values obtained for each distance are added, and a value obtained by dividing the added value by the number of pixels is obtained. This value is the variance.

  In the present invention, the roughness of the outer peripheral surface of the roller appears as the height difference of the unevenness on the contour line of the roller detected from the black and white binary image of the roller. The degree of unevenness in the height difference of the unevenness is grasped as the dispersion of the distance between the reference line set parallel to the central axis of the roller and the plurality of pixels constituting the contour line. The larger the dispersion, the greater the height or number of protrusions formed on the outer peripheral surface of the roller. That is, a large dispersion of distance corresponds to a decrease in recording quality of an image printed on recording paper. Therefore, by determining the roughness of the outer peripheral surface of the roller based on the magnitude of the distance dispersion, it is possible to determine a roller that does not deteriorate the recording quality of the image printed on the recording paper.

  According to a second aspect of the present invention, in the first aspect of the invention, the black and white binary image is an image of the same roller projected in a direction orthogonal to the central axis of the roller. .

  In the present invention, since the boundary line between the projection area of the roller and the other area can be easily detected as the contour line of the outer peripheral surface of the roller, unlike the appearance image of the roller using reflected light, The outline of the outer peripheral surface of the roller can be detected without performing the value processing.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the roughness of the outer peripheral surface of the roller is determined at a plurality of positions in the circumferential direction.
In the present invention, it is possible to more accurately determine the roughness of the entire outer peripheral surface of the roller.

  According to the present invention, it is possible to objectively grasp the roughness of the outer peripheral surface of a roller made of a porous elastic body, and as a result, it is possible to improve the efficiency of quality judgment work and to suppress variations in quality judgment. There is an effect that can be done.

Next, an embodiment embodying the present invention will be described with reference to FIGS.
As shown in FIG. 1, a roller 10 whose outer peripheral surface is inspected for roughness by the roller inspection method of this embodiment is a roller made of a porous elastic body such as polyurethane foam on the outer periphery of a core metal 11. The main body 12 is supported. Such a roller 10 is manufactured as follows. That is, first, a rectangular column is cut out from a strip-shaped porous elastic body foamed or slab foamed, and the rectangular column and the core metal 11 are integrated by an adhesive through a core metal 11 in a hole formed in the rectangular column along the longitudinal direction. Make it. Next, the surface of the rectangular column supported by the core metal 11 is ground into a cylindrical shape with a grindstone to form the roller body 12. Fluffy protrusions are often formed on the outer peripheral surface of the roller main body 12 of the roller 10 thus manufactured. For this reason, the roughness of the outer peripheral surface of the roller body 12 due to the plurality of protrusions is inspected by a roller inspection method.

Next, a method for inspecting the roughness on the outer peripheral surface of the roller body 12 will be described with reference to the flowchart of FIG.
First, in step (hereinafter abbreviated as S) 100, a projector 20 as shown in FIG. 4 is operated by an operator to project an image in a direction orthogonal to the central axis of the roller body 12, The projection image is acquired. The projector 20 includes a light emitting diode 21, a light projecting lens 22, a light projecting side mirror 23, a stage glass 24, a first light receiving lens 25, a light receiving side mirror 26, a second light receiving lens 27, a two-dimensional CCD ( (Charge Coupled Device) image sensor 28, signal processor 29, and the like. In the projector 20, the illumination light projected from the light emitting diode 21 is collimated by the light projecting lens 22 and then projected onto the stage glass 24 on which the roller 10 is placed. This light is focused by the first light receiving lens 25 after passing through the stage glass 24. Further, the light is collimated by the second light receiving lens 27 through the light receiving side mirror 26 and then incident on the two-dimensional CCD image sensor 28. The light incident on the two-dimensional CCD image sensor 28 is converted into an analog electric signal and then input to the signal processing unit 29. And the projection image 30 of the roller 10 as shown in FIG. The projection image 30 is composed of a black region corresponding to the projection region of the image of the roller 10 and a white region corresponding to the other region, and is substantially a monochrome binary bitmap image. Therefore, the contour line of the outer peripheral surface of the roller body 12 is clearly shown in the projection image 30. The data of the projection image 30 is output to an external computer 31 that is electrically connected to the signal processing unit 29.

  Next, in S101, the contour line of the roller body 12 is obtained from the projection image 30 (black and white binary image) of the roller body 12 by the external computer 31 that operates based on a preset program as shown in FIG. 32 is detected. The detection of the contour line 32 is performed by extracting the pixel of the portion where the density difference between black and white is generated. Accordingly, the contour line 32 is composed of a chain of pixels that form a boundary line between a black region corresponding to the projection region of the image of the roller 10 and a white region corresponding to a region other than the projection region in the projection image 30. . The unevenness of the contour line 32 represents the roughness of the outer peripheral surface of the roller body 12.

  Next, in S102, the following processing is executed by the external computer 31. That is, as shown in FIG. 6, the coordinates of each pixel 33 are grasped in a coordinate system in which the reference line 34 set parallel to the central axis of the roller 10 is the X axis and the direction orthogonal to the reference line 34 is the Y axis. Is done. Next, a distance Y (i) between each pixel 33 constituting the contour line 32 and a reference line 34 set in parallel to the central axis of the roller body 12 is obtained. As shown in FIG. 6, the interval δ between the pixels 33 adjacent to each other in the X-axis direction on the contour line 32 corresponds to, for example, 40 μm in actual distance.

Here, n is the total number of pixels 33 constituting the contour line 32.
Next, in S104, it is compared by the external computer 31 whether or not the variance σ ² exceeds a preset determination value, and the roughness of the outer peripheral surface of the roller body 12 is based on the comparison result. The result of determining whether or not is good is displayed on a display (not shown). This determination result is a result of inspecting the roughness of the outer peripheral surface of the roller body 12 on one ridge line of the outer peripheral surface. For this reason, as shown in FIG. 7, the roughness of the outer peripheral surface of the roller body 12 is inspected at a plurality of positions in the circumferential direction of the roller body 12, for example, the positions A1 to A6 whose center angles are shifted by 45 degrees. . And when dispersion | distribution (sigma) ² obtained from any position A1-A6 of the outer peripheral surface of the roller main body 12 exceeds the determination value, the roller 10 is determined as a defective product based on the display result of the display. .

According to the roller inspection method of this embodiment described in detail above, the following effects can be obtained.
(1) The contour line 32 of the outer peripheral surface of the roller main body 12 is detected from the projection image of the roller 10, the coordinates of a plurality of pixels 33 constituting the contour line 32 are grasped, and parallel to the central axis of the roller 10. The distances Y (i) between the set reference line 34 and the plurality of pixels 33 are obtained. Then, the roughness of the outer peripheral surface of the roller body 12 is determined based on the variance σ ² obtained from the value of each distance Y (i). Therefore, unlike the case where the operator visually determines the roughness of the outer peripheral surface of the roller body 12, the efficiency of the quality work is improved and the variation in the quality determination of the roller 10 can be suppressed. In addition, the greater the variance σ ² of the distance Y (i), the greater the number of high protrusions formed on the outer peripheral surface of the roller body 12. That is, a large variance σ ² of the distance Y (i) corresponds to a decrease in recording quality of an image printed on recording paper in a printer or a copying machine. Therefore, by determining whether or not the roughness of the outer peripheral surface of the roller body 12 is good by the variance σ ² , it is possible to determine the roller 10 that does not deteriorate the recording quality of the image printed on the recording paper.

  (2) Since the projected image 30 of the roller body 12 is used, the boundary line between the projected area of the image of the roller body 12 and the other area can be easily detected as the contour line 32 of the roller body 12. For this reason, unlike the appearance image of the roller main body 12 using reflected light, the contour line 32 of the roller main body 12 can be detected without performing the binarization processing of the image.

  (3) The roughness of the outer peripheral surface of the roller body 12 is determined at a plurality of positions in the circumferential direction. Therefore, since the roughness of the entire outer peripheral surface of the roller body 12 can be determined more accurately, the roller 10 with higher quality can be determined.

  Next, an example of this embodiment configured as described above will be described.

When the roller 10 was used as a toner supply roller of a printer, the relationship between the dispersion σ ² and the image recording quality was examined.
・ Printer used: Sharp Corporation AR-C262FP
-Test environment: Environmental temperature 23 ° C, environmental humidity 55%
Test conditions: A pattern image output with 50% halftone was compared with an image sample output using a current toner supply roller to determine the recording quality.

As shown in Table 1, it is estimated that there is a clear correlation between the variance σ ² and the image recording quality. Therefore, by determining the roughness of the outer peripheral surface of the roller body 12 based on the dispersion σ ² of the distance Y (i), a roller that can maintain the image recording quality at a certain level or more when used as a toner supply roller. 10 can be discriminated with a certain discrimination accuracy.

In addition, this embodiment can also be changed and embodied as follows.
For example, distances Y (i) between every other pixel 33 constituting the contour line 32 and the reference line 34 are obtained, and the variance σ ² of each distance Y (i) is obtained. . In this way, since the number of pixels to be processed can be reduced, the time required for processing can be shortened.

-The central axis of the roller 10 is used as the reference line.
-Only the variance σ ² is displayed on the display, and the operator determines whether or not the roughness of the outer peripheral surface of the roller body 12 is good.

The roller 10 is imaged in a direction orthogonal to the central axis to obtain an appearance image, and the appearance image is binarized to obtain a black and white binary image. Then, the variance σ ² of the distance Y (i) is obtained from this black and white binary image by the same processing as in the above embodiment.

FIG. 3 is a front view of a part of the roller according to the embodiment. Projected image of the roller body. The flowchart which shows the test | inspection procedure of the outer peripheral surface of a roller main body. The block diagram which shows the structure of an inspection system. The figure which shows one outline of the outer peripheral surface in a roller main body. The schematic diagram which shows the pixel which comprises an outline. The side view which shows a roller.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Roller, 12 ... Roller main body, 30 ... Projection image as black and white binary image, 32 ... Contour line, 33 ... Pixel, 34 ... Reference line, A1-A6 ... Position, Y (i) ... distance, σ ² ... dispersion.

Claims (3)

A roller inspection method for inspecting the roughness of the outer peripheral surface of a roller made of a porous elastic body,
Detecting the contour of the outer peripheral surface of the roller from the black and white binary image of the roller, grasping the coordinates of a plurality of pixels constituting this contour,
Each of the distance between the reference line set in parallel to the central axis of the roller and the plurality of pixels is obtained,
Find the variance of each distance value,
A roller inspection method, wherein the roughness of the outer peripheral surface of the roller is determined based on the magnitude of the dispersion.   The roller inspection method according to claim 1, wherein the black and white binary image is an image of the roller projected in a direction orthogonal to the central axis of the roller.   The roller inspection method according to claim 1, wherein roughness of the outer peripheral surface of the roller is determined at a plurality of positions in a circumferential direction of the roller.

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