JPH02201144A - Abnormality detector for surface of coating material - Google Patents

Abstract

PURPOSE:To surely and accurately detect the abnormality of the surface of a coating material by scanning the surface with laser light in a prescribed direction and removing the signal of a prescribed frequency band from the information detection signal thereof. CONSTITUTION:The laser light from a light source 11 is projected via a rotary polyhedral mirror 13 to a photosensitive drum 30 and scans the drum in the axial center direction thereof. The laser light is made incident on the surface of the drum 30 while the incident angle thereof is successively changed in the scanning direction. The reflected light from the drum 30 is made incident to a photodetector 20 and the voltage corresponding to the light intensity is detected by a photoelectron multiplier 22. This voltage is inputted via a noise filter 23 to an arithmetic processing section, etc. The abnormality on the drum 30 surface is inspected by the repetition of such operation over the entire surface.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a coating in which a coating layer is provided on a substrate, such as a photoreceptor used in an image forming apparatus such as a copying machine or a laser printer. The present invention relates to a device for detecting abnormalities on the surface of objects.

(Prior Art) Photoreceptor drums used in image forming devices such as copying machines and laser printers are usually made by directly attaching them to aluminum tubes.
Alternatively, a photosensitive layer is coated with an alumite layer interposed therebetween. Such a photoreceptor drum cannot form a good image if its surface (photoreceptor layer surface) is scratched or has foreign matter such as dust attached. The surface of the photosensitive layer is inspected to see if there are any abnormalities such as scratches or adhesion of foreign matter.

For inspection of the surface of the photoreceptor drum, for example, Japanese Patent Application Laid-Open No. 61-2
The device disclosed in Publication No. 0080 is used. This device irradiates the surface of the photoreceptor drum with light and detects abnormalities on the surface of the photoreceptor drum based on the amount and intensity of the reflected light.

Recently, coherent laser light has been used in such photoreceptor drum surface inspection devices to improve inspection accuracy and inspection speed. Photoconductor drum abnormality detection equipment uses laser light.
Laser light emitted from a laser light source is directly irradiated onto the surface of the photoreceptor drum by a scanning means such as a rotating polygon mirror, and the surface of the photoreceptor drum is scanned in a predetermined direction. The laser beam reflected by the photoreceptor drum is incident on a photomultiplier tube that detects optical information of the laser beam, for example, and the intensity of the laser beam is detected by the photomultiplier tube as, for example, a voltage. Ru. When there is an abnormality such as a scratch on the surface of the photoreceptor drum, the laser light is diffusely reflected at the abnormal part, and the intensity of the laser light incident on the photomultiplier tube is reduced. Therefore, an abnormality on the surface of the photoreceptor drum is detected based on the voltage corresponding to the intensity of the laser light output by the child multiplier.

(Problems to be Solved by the Invention) As mentioned above, the photosensitive drum has a photosensitive layer on the outer peripheral surface of the aluminum tube, either directly or via an alumite layer. When a photosensitive drum on which a photosensitive layer is laminated is irradiated with laser light, part of the laser light is reflected by the surface of the photosensitive layer, but the rest enters the photosensitive layer. When the laser light that has entered the photosensitive layer is diffusely reflected within the photosensitive layer,
The amount of laser light transmitted through the photosensitive layer is small, and therefore the amount of laser light reflected at the interface between the photosensitive layer and the aluminum tube is small, and the laser light reflected at the interface is However, when the light transmittance of the photosensitive layer is high, the amount of laser light reflected at the interface between the photosensitive layer and the aluminum tube increases, and the amount of laser light emitted from the photosensitive layer increases. To increase. A rotating polygon jl! is applied to the photosensitive layer of the photosensitive drum. Since the laser beam scanned by the scanning means such as It changes sequentially while being scanned along the axial direction. For this reason, the phase of the laser beam reflected by the photosensitive layer and the laser beam reflected at the interface between the photosensitive layer and the aluminum tube described above and emitted from the photosensitive layer is shifted, causing interference between the two. As the laser beam scans, this phase difference changes sequentially along the fine direction of the photoreceptor drum, and so-called interference fringes, which are bright and dark patterns, are generated on the photoreceptor drum. Since the laser beam reflected by the photosensitive drum is incident on, for example, a photomultiplier tube, the interference fringes described above are superimposed as noise on the detection signal of the photomultiplier tube. In such a state, there is a possibility that an abnormality on the surface of the photoreceptor drum cannot be detected.

The present invention solves the above-mentioned conventional problems, and its purpose is to provide an abnormality detection device on the surface of a coated object that can reliably and accurately detect abnormalities on the surface of the coated object using laser light. It is in.

(Means for Solving the Problems) The abnormality detection device for a coated object of the present invention detects an abnormality on the surface of the coated object by irradiating a laser beam onto the surface of the coated object, which has a coating layer provided on a substrate. The apparatus includes a laser light source, a scanning means for sequentially scanning the laser light emitted from the laser light source in a predetermined direction on the surface of the coated object, and capturing reflected light of the laser light irradiated onto the surface of the coated object. The above-mentioned object is achieved by comprising: a detection means for detecting the optical information of the detection means; and a filter for removing signals in a predetermined frequency band from the detection signal of the detection means.

(Example) The present invention will be described below with reference to Examples.

FIG. 1 is a schematic diagram of an apparatus for detecting an abnormality on the surface of a coated object according to the present invention. The detection device is used, for example, to detect an abnormality on the surface of a photosensitive drum 30 used in an image forming bag W of a copying machine or the like. The photosensitive drum 30
A photosensitive layer is directly laminated on the outer peripheral surface of an aluminum tube. The photosensitive drum 30, which is the object to be inspected, is
It is placed on a horizontal stage 16. The stage 16
is housed in the output shaft of a stepping motor 15 disposed below the stage 16, and the stage 16 is intermittently rotated by the stepping motor 15.

On the side of the photosensitive drum 30 placed on the stage 16, there is a laser light source 11 that emits a He-He laser beam.
is installed. Laser light emitted from the laser light source 11 is irradiated via reflecting mirrors 18 and 19 onto a rotating polygon mirror 13, which is a laser light scanning means. The rotary polygon jl13 has a rotation axis perpendicular to the irradiated laser light, and the laser light irradiated to the rotary polygon j113 is directed to the photoreceptor drum 3 placed on the stage 16.
It is reflected towards the surface of 0. Then, the rotating polygon jH3
Due to its rotation, the photosensitive drum 3 on the stage 16
The laser beam reflection position of the first rotor surface bell 13, which sequentially scans the laser beam in the axial direction of 0, is opposite to the center of the photosensitive drum 30. The incident angle of the light with respect to the scanning direction changes sequentially on the surface of the photoreceptor drum 30, and the maximum (
9Q''), which is the minimum at each end.

The laser beam that is scanned along the axial direction of the surface of the photoreceptor drum 30 is reflected by the surface of the photoreceptor drum 30 at a predetermined reflection angle with respect to the radial direction, and is directed to the light receiver 20. irradiated. The light receiver 20 has a light receiving surface parallel to the axial direction of the photoreceptor drum 30, and a light receiving window is provided on the light receiving surface. The length of the light receiving window is the photosensitive drum 30.
The light receiving window has a diffuser plate 21 made of ground glass, for example, attached to the light receiving window. The laser beam reflected by the photoreceptor drum 30 enters the interior of the light receiver 20 via the diffusion plate 21 .

A photomultiplier tube 22 for detecting the intensity of the laser beam reflected from the photoreceptor drum 30 is disposed inside the photoreceptor 21 as a means for detecting optical information of the laser beam reflected from the photoreceptor drum 30. The laser beam reflected by the body drum 30 is diffused by the diffusion plate 21 and enters the photomultiplier tube 22 . The diffusion plate 21 eliminates unevenness in the amount of laser light that passes through the enlarged L plate 21 and enters the photomultiplier tube 22. The photomultiplier tube 22 outputs an fS voltage corresponding to the intensity of the incident laser beam.

The output signal of the photomultiplier tube 22 is filtered through a noise filter 23.
It is output to. The noise filter 23 removes low frequencies in a predetermined band from the output signal of the photomultiplier tube 22 . The output of the noise filter 23 is input to a predetermined arithmetic processing section, display section, storage section, etc.

In the inspection device for the surface of a coated object with such a configuration,
The laser light emitted from the laser light source 11 is reflected 1
The light is irradiated onto the rotating polygon mirror 13 via 18 and 19.

The rotating polygon mirror 13 reflects the irradiated laser light toward the surface of the photoreceptor drum 30 placed on the stage 16, thereby transferring the laser light to the photoreceptor drum 30.
The surface of the photoreceptor drum 3 is directly irradiated, and its rotation causes the photoreceptor drum 3 to
Scan sequentially in the direction of the 0 axis. As a result, the corresponding! Laser light is incident on the surface of the five-light drum 30, with the incident angle changing sequentially with respect to the scanning direction.

The laser beam irradiated onto the photoreceptor drum 30 is reflected by the photoreceptor drum 30 and sequentially irradiated onto the light receiver 20 . After passing through the diffuser plate 21 of the light receiver 20, the laser light irradiated onto the light receiver 20 is applied to a photomultiplier tube 22, which is an optical information detection means for the laser light disposed inside the light receiver 20. It will be done. The photomultiplier tube 22 sequentially detects the intensity of the incident laser light and outputs a voltage corresponding to the intensity.

The output signal of the photomultiplier tube 22 is filtered through a noise filter 23.
The data is input to a predetermined arithmetic processing unit, display device, storage device, etc. via the .

When the laser beam is scanned from one end to the other along the fine details of the photoreceptor drum 30, the stepping motor 15 is driven, the stage 16 is rotated by a predetermined amount, and the rotating polygon mirror is rotated by a predetermined amount. The position of the laser beam irradiated onto the surface of the photoreceptor drum 30 on the stage 16 at step 13 is adjacent to the position of the laser beam scanned immediately before. Then, the photosensitive drum 30 is scanned with laser light, and the scanned laser light is sequentially incident on the photomultiplier tube 22 of the light receiver 21). By sequentially repeating such operations, the photosensitive drum 3
A laser beam is scanned over the entire 0 surface, and an abnormality inspection is performed over the entire surface.

As described above, the laser beam irradiated onto the photoreceptor drum 31 changes its incident angle sequentially with respect to the scanning direction on the surface of the photoreceptor drum 30.
is being scanned in the axial direction. Therefore, when the laser beam reflected at the interface between the photosensitive layer and the aluminum tube in the photosensitive drum 30 is emitted from the surface of the photosensitive layer,
At the time of emission, the laser beam that is irradiated onto the photosensitive layer and directly reflected on the surface of the photosensitive layer is out of phase with the laser beam, and the two interfere with each other. Furthermore, as the phase difference laser beam scans, it changes sequentially along the fine direction of the photoreceptor drum 31). As a result, when the interference laser beam reflected by the photosensitive drum 30 is incident on the photomultiplier tube 22 in the photoreceiver 20, the photoelectron 1'11 multiplier tube 22
Interference fringes are superimposed on the second detection signal as noise.

The output signal of the photomultiplier tube 22 is filtered through a noise filter 23.
The noise filter 23 removes low frequencies in a predetermined band from the output signal of the photomultiplier tube 22 .

When inspecting the surface of the photoreceptor drum 30 with laser light, the photoreceptor drum as the object to be inspected has a length of 35 mm.
f) Organic photoreceptor drum of m+++ (relative refractive index of photosensitive layer 2
．． 5-4. θ, and its film thickness is 10 to 40 μm), at each end of the photosensitive drum, the laser beam reflected by the photosensitive layer and the laser beam reflected at the interface between the photosensitive layer and the aluminum tube. The period of the interference light with the laser beam emitted from the photosensitive layer becomes the maximum, and the maximum period per 10 m is about 4.75 periods (wavelength of interference fringes 2.b+n
On the other hand, at the center of the photoreceptor drum in the axial direction, the period of the interference light is minimum, which is 10 am.
The minimum cycle per cycle is about 0.0153 cycles (wavelength of interference fringes is about 652.1 m). Therefore, when inspecting the surface of such a photoreceptor drum, the noise filter 23 should be is 652. From lea level to 2.1
．． It is sufficient to use one that can remove noise of about aI.However, usually, the minimum wavelength of this interference light is 2.1■
Since larger scratches and foreign objects can be detected visually, there is no practical problem as long as a noise filter that can remove only noise smaller than this minimum wavelength is used.Normally, the scanning speed of the laser beam is , 1 per 0.5μ56C
Therefore, in order to remove the noise with the minimum wavelength of the interference light of about 2.1 m, a noise filter that can remove a period of 1.05 μsec or less, that is, a frequency band of about I MHz or less, is used. It will be done.

In this way, low frequencies in a predetermined band are removed from the output signal of the photomultiplier tube 22 by the noise filter 23. If there is an abnormality such as a scratch on the surface of the photoreceptor drum 30, the laser light is diffusely reflected at the abnormal part, and the intensity of the laser light incident on the photomultiplier tube 22 is reduced. When the intensity of the laser beam incident on the photomultiplier tube 22 decreases, the output voltage value of the photomultiplier tube 22 decreases. Since noise in a predetermined frequency band is removed from the output voltage of the photomultiplier tube 22 by the noise filter 23, the output voltage of the noise filter 23 has decreased due to diffused reflection due to the presence of an abnormality on the surface of the photoreceptor drum 30. can be easily detected, and scratches on the surface of the photoreceptor drum 30, adhesion of foreign matter, etc. can be found very easily.

(Effects of the Invention) In this way, the apparatus for detecting abnormalities on the surface of a coated object of the present invention is configured such that the laser beam sequentially scanned by the predetermined scanning means is applied to the surface of the coated object, which is the object to be inspected. The direct reflected light and the reflected light at the interface of the coating layer interfere with each other, but noise is removed by a predetermined filter from the detection signal of the detection means that detects the optical information of the interference light. Therefore, abnormalities on the surface of the coated object can be detected reliably and accurately.

, .

11... Laser light source, 13... Rotating polygon mirror, 15
...Stepping motor, 16... Stage, 2
0... Photoreceiver, 22... titanium multiplier, 23...
·Noise filter.

that's all

Claims (1)

[Claims] 1. An apparatus for detecting abnormalities on the surface of a coated article by irradiating the surface of a coated article with a coating layer on a substrate, comprising: a laser light source; and the laser light source. scanning means that sequentially scans the laser beam emitted from the coating object in a predetermined direction on the surface of the coating object; a detection means that captures the reflected light of the laser beam irradiated onto the surface of the coating object and detects its optical information; An abnormality detection device on the surface of a coated object, comprising: a filter that removes a signal in a predetermined frequency band from a detection signal of the detection means.