JPH10332534A - Laser optical system inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily inspect whether a foreign object such as dust is adhered to a laser optical system and, for example, distortion or waviness is generated or not. SOLUTION: A laser light source 12 is totally lit by a laser control part 14, and laser beams LB are scanned while rotating a polygonal mirror 32. A CCD camera 18 is arranged at the image-forming position of the laser beams LB, and an electric charge is accumulated for each pixel when the laser beams LB are received and is outputted to a monitor 20 as illumination data. The illumination data are binarized by a specific threshold level and are displayed on a screen, thus viewing the trace of the laser beams LB being extended in scanning direction. When a foreign object is adhered to a laser optical system 16, the laser beams LB are screened by the foreign object, thus detecting the foreign object from the break of the trace being displayed on the monitor 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser optical system inspection apparatus, and more particularly, to a laser optical system inspection apparatus that inspects a laser optical system for irradiating a laser beam onto a surface to be irradiated and scanning the surface.

[0002]

2. Description of the Related Art Conventionally, for example, in a copying machine, a facsimile or a printer using an electrophotographic process, a laser beam is scanned on the surface of a photosensitive drum via a laser optical system to form a desired latent image. An image forming system is configured to form an image by attaching toner to the latent image and transferring the latent image to paper. In this type of image forming system, laser light is scanned through a laser optical system including a mirror surface (for example, a polygon mirror) and a lens. Therefore, dust adheres to the mirror surface and the lens constituting the laser optical system. If distortion or undulation occurs, an appropriate image cannot be formed. Therefore, when inspecting the laser optical system for defects in a conventional image forming system, a laser beam is irradiated onto the photoreceptor (image forming surface), and the beam size and light intensity are determined from the formed image. There has been used a laser optical system inspection apparatus or the like that measures a reflected laser beam diameter by making a determination or operating a measuring device by adjusting a polygon mirror (rotating polygon mirror) to a predetermined measurement point.

[0003]

However, in such a conventional laser optical system inspection apparatus, when inspecting the laser optical system, many points such as setting measurement points and operating a measuring instrument are required. It takes time and effort, and the measurement result is only for the measurement point. If a foreign matter (dust or the like) is attached to a place other than the measurement point, it may be overlooked. Therefore, the inspection may be performed at all points where the laser beam is scanned. However, as described above, the conventional laser optical system inspection apparatus is practically difficult because the inspection requires time and effort. in this way,
When a foreign substance is attached to the laser optical system, the laser beam that is going to pass through that part is blocked and does not reach the photoreceptor to be irradiated. However, there was a problem that white streaks (black streaks depending on the process) occurred. Further, when a mirror surface or a lens constituting the laser optical system is distorted or undulated, the optical path of the laser light is distorted, so that there is a disadvantage that an appropriate image cannot be formed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a laser optical system which irradiates a laser beam onto a surface to be irradiated and scans the surface. Another object of the present invention is to provide a laser optical system inspection apparatus capable of performing inspection by visually observing occurrence of distortion or undulation by an image display means. It is an object of the present invention to provide a laser optical system inspection apparatus in which a received light output is not saturated by adjusting a received light amount of a laser beam irradiated to an image sensor by a filter. A third object of the present invention is to provide a laser optical system inspection apparatus for inspecting a laser optical system by comparing illuminance between adjacent divided regions in a scanning direction based on data of irradiation of a laser beam to an image sensor. To provide. A fourth object of the present invention is to provide a laser optical system inspection apparatus for inspecting a laser optical system by obtaining an illuminance distribution of all divided regions in a scanning direction based on laser beam irradiation data on an image sensor. Is to do. An object of the present invention is to provide a laser optical system inspection capable of visually inspecting irradiation data of laser light applied to an image sensor by an image display means by controlling a lighting pattern of the laser light. It is to provide a device. It is an object of the present invention to provide a laser optical system inspection apparatus capable of selecting a mirror surface of a rotary polygon mirror of a laser optical system by controlling lighting of a laser beam.

[0005]

According to the first aspect of the present invention, there is provided a laser optical system inspection apparatus for inspecting a laser optical system which irradiates a laser beam from a laser light source onto a surface to be irradiated and performs scanning. An image pickup element that is arranged at an image forming position of the laser light irradiated with the laser light and detects laser light in a predetermined irradiation area irradiated through the laser optical system; and Moving means for moving;
Image display means for displaying an image of the irradiation data of the laser light taken into the image pickup device. According to the first aspect, the image pickup device is disposed at an image forming position where the laser light is irradiated, detects the laser light in a predetermined irradiation area irradiated through the laser optical system, and moves the image pickup device by the moving unit. The laser beam is moved in the scanning direction of the light, and the irradiation data of the laser light taken into the image sensor by the image display means is displayed as an image. For this reason, when a foreign substance is attached to the laser optical system or when distortion or undulation occurs, the inspection can be performed by visually observing the displayed image. Claim 2
According to the invention described in (1), in the laser optical system inspection apparatus according to claim 1, a filter that adjusts a light receiving amount of laser light applied to an image sensor is arranged between the laser optical system and the image sensor. It is characterized by. According to claim 2,
By disposing a filter for adjusting the amount of laser light received on the image sensor between the laser optical system and the image sensor, an undetectable state due to saturation of the output of the image sensor can be prevented. .

[0006] The invention described in claim 3 is the invention according to claim 1 or 2.
In the laser optical system inspection device according to the above, the irradiation data taken in when scanning while continuously irradiating the imaging device with laser light is divided into a plurality of regions in the scanning direction of the laser light, the adjacent divided regions It is characterized by further comprising detecting means for comparing the illuminance and detecting a change in the illuminance. According to the third aspect, the irradiation data taken into the image sensor by the detection unit is divided into a plurality of regions in the scanning direction of the laser light, and the illuminance of adjacent divided regions is compared to detect a change in illuminance. Foreign matter and the like attached to the laser optical system can be detected. The invention described in claim 4 is
3. The laser optical system inspection apparatus according to claim 1, wherein irradiation data taken in when scanning while continuously irradiating the imaging element with laser light is divided into a plurality of regions in a scanning direction of laser light, And a detecting unit for detecting an illuminance distribution by obtaining the illuminance of the divided area. According to the fourth aspect of the present invention, the irradiation data taken into the image sensor by the detecting means is divided into a plurality of regions in the scanning direction of the laser beam, and the illuminance distribution is detected by obtaining the illuminance of all the divided regions. Foreign matter and the like attached to the system can be detected.

[0007] The invention according to claim 5 is the invention according to claim 1 or 2.
In the laser optical system inspection device according to the above, further comprising a lighting control means for controlling the lighting and extinguishing of the laser light emitted from the laser light source, the laser light emitted in a predetermined lighting pattern by the lighting control means Irradiation data irradiating the image sensor is displayed as an image on the image display means. According to the fifth aspect, by controlling lighting and extinguishing of the laser light emitted from the laser light source by the lighting control means, the image pickup device is irradiated with the laser light emitted in a predetermined lighting pattern to the image display means. By displaying an image and visually observing the degree of disturbance of the displayed pattern, distortion or undulation of the laser optical system can be detected. According to a sixth aspect of the present invention, in the laser optical system inspection apparatus according to the fifth aspect, the laser optical system has a rotary polygon mirror for scanning a laser beam, and the lighting control means includes a rotary polygon mirror. A mirror surface selecting unit for performing lighting control in synchronization with the rotation to select a mirror surface is further provided. According to the sixth aspect, when the laser optical system has a rotating polygonal mirror for scanning laser light, a mirror surface selecting unit that performs lighting control in synchronization with the rotation of the rotating polygonal mirror and selects a mirror surface is provided. Since the lighting control means is further provided, it is possible to selectively use only an appropriate mirror surface of the rotary polygon mirror.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION

<< First Embodiment >> Hereinafter, a first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the first
FIG. 2 is a block diagram of the laser optical system inspection apparatus 10 according to the embodiment, and FIG. 2 shows a locus of the laser beam LB displayed on the monitor 20 of the laser optical system inspection apparatus 10 in FIG. FIG. 3 shows a locus of the laser beam LB displayed on the monitor 20 when a foreign substance is attached to the laser optical system 16 of the laser optical system inspection apparatus 10 of FIG. 1, and FIG. The lighting control state of the laser beam LB is shown. The laser optical system inspection apparatus 10 according to the first embodiment is implemented as a laser optical system inspection apparatus that forms a latent image on a photosensitive drum of a copying machine using, for example, an electrophotographic process. In FIG. 1, a laser optical system inspection apparatus 10 includes a laser light source 12 for generating a laser beam LB, and a laser control unit 1 for controlling light emission of a laser beam LB generated from the laser light source 12.
4. A laser optical system 16 which focuses the laser beam LB and irradiates it while scanning the irradiation surface, and a CCD (Charge Coupled Device) as an image pickup device for inspection of the laser optical system arranged at an image forming position of the laser beam LB. : A charge-coupled device) as a moving means that enables inspection in the entire irradiation region of the laser beam LB by holding the camera 18 and the CCD camera 18 and sliding them in the scanning direction of the laser beam (the direction of the arrow in the figure). Slide stage 19, CCD
A monitor 20 such as a CRT or a liquid crystal display as image display means for displaying the irradiation data of the laser beam LB captured by the camera 18 as an image, and the laser optical system 16 and C
It is composed of a filter 22 and the like provided between the CD camera 18 and attenuating a laser beam. Further, the laser optical system 16 includes a lens 30 that focuses the laser beam LB generated from the laser light source 12 to a predetermined beam diameter,
A polygon mirror 32 composed of a rotatable polygon mirror for scanning the focused laser beam LB, a polygon mirror 32
Motor 34, polygon mirror 3 for rotating
Various mirrors 36, 38, 40, 42, 4 for transmitting or reflecting the laser beam LB reflected and scanned by the laser beam 2
4 and the like.

Next, the operation will be described. The lens 30 of the laser optical system 16 and various mirrors 36, 38, 42, 4
When foreign matter such as dust adheres to the photosensitive drum 4, the laser beam is partially emitted by the foreign matter, so that an image formed on a photosensitive drum (not shown) is incomplete. Therefore, in order to detect a foreign substance attached to the laser optical system 16, a laser control unit 14 that controls light emission of the laser light source 12 is used.
As shown in FIG. 4, the polygon mirror 32 of the laser optical system 16 is
Rotate by 4. Then, the laser beam LB emitted from the laser light source 12 rotates while the mirror surface of the polygon mirror 32 is irradiated on the mirror surface, so that the incident angle and the output angle of the mirror gradually change, and the irradiated surface is scanned. Can be done. Here, when inspecting the laser optical system 16, as shown in FIG. 1, normally, the CC is located at the image forming position of the laser beam LB where the photosensitive drum is arranged.
When the D camera 18 is arranged and the polygon mirror 32 comes to a position where the laser beam LB is projected on the image forming surface 18a of the CCD camera 18, electric charges corresponding to the illuminance are accumulated in each pixel of the CCD camera 18, Irradiation data can be captured.

The polygon mirror 32 of the first embodiment
Is rotated at a high speed by the polygon motor 34, so that the shutter speed of the CCD camera 18
By appropriately selecting the filter 22 that attenuates the laser beam LB, the output value of each pixel of the CCD camera 18 does not saturate, and an output value sufficient to perform arithmetic processing using the output value is obtained. Adjust to obtain. In this adjusted state, the irradiation data captured by the CCD camera 18 is binarized in the monitor 20 to display an image. Here, the binarization level (threshold level) in the monitor 20 is set in the vicinity of the middle of the output value from the CCD camera 18, and pixels having an output value higher than the threshold level are “black” and below the threshold level. Are displayed in “white”, a locus 50 of the laser beam LB extending in the scanning direction is displayed on the screen of the monitor 20 as shown in FIG. Such inspection operation of the laser optical system is performed while sequentially moving the CCD camera 18 on the slide stage 19 in the scanning direction (the direction of the arrow in the figure).
In the entire region of No. 6, the same monitor inspection is performed.

If foreign matter is attached to the lens 30 of the laser optical system 16 or the various mirrors 36, 38, 42, 44, etc., the laser beam LB is blocked by the foreign matter, so that the CCD camera 18 Does not reach the imaging surface 18a. In the screen on the monitor 20 in this case, as shown in FIG. 3, a portion where the laser beam LB is not received due to a foreign substance or the like is displayed as a missing portion 52 in the middle of the trajectory 50. For this reason, due to the positional relationship between the position of the CCD camera 18 on the slide stage 19 and the cutout 52 on the screen, foreign matter or the like adheres to any part of the laser optical system 16 (the lens and mirror cannot be distinguished). Can be grasped to some extent.

As described above, according to the first embodiment, the CC arranged at the image forming position of the laser beam LB is used.
The laser beam LB emitted while being scanned by the D camera 18 via the laser optical system 16 is imaged, and the captured image is displayed on the monitor 20 and visually inspected, thereby attaching to the laser optical system 16. The presence or absence of foreign matter such as dust can be detected. Also, depending on the degree of distortion of the displayed image, it is possible to detect distortion, undulation, and the like generated in the lens and mirror of the laser optical system. And CC
Since the D camera 18 can be moved in the scanning direction on the slide stage 19, it is possible to execute the inspection in the entire area of the laser optical system 16. In the above-described first embodiment, the filter 22 that appropriately attenuates the laser beam received by the CCD camera 18 so that the output does not become saturated is used. The same effect may be obtained by adjusting the sensitivity of the CCD camera 18.

<< Second Embodiment >> Next, a second embodiment will be described with reference to FIGS. Here, the same reference numerals are given to the same or equivalent components as those of the first embodiment, and the description thereof will be simplified or omitted. Although the schematic configuration of the laser optical system inspection apparatus 10 of FIG. 1 is common, if there is a feature in the added portion or the internal configuration, it will be described each time. In the second embodiment, when a defect due to foreign matter such as dust is minute, the missing portion 52 may not be clearly displayed on the screen as shown in FIG. 3 in the first embodiment. That is, 2 using the threshold level
When the binarization is performed, a subtle illuminance difference is discarded, so that it may not be possible to determine the difference on the screen. In such a case, as shown in FIG. 1, the output of the CCD camera 18 is input to a signal processing unit 60 as a detecting means, and the presence or absence of foreign matter such as dust is detected by performing signal processing. is there. The signal processing unit 60 performs an arithmetic process on the output of the CCD camera 18 in fixed frame units, stores the result,
It is composed of a microcomputer or the like that can compare the stored calculation results.

Next, the operation will be described. First, the signal processing unit 60 defines a fixed frame 62 with respect to the image plane of the CCD camera 18 as shown in FIG. This frame 62 is
It is not necessary to match the pixels of the CD camera 18, but the smaller the size of the area of one frame 62, the finer the dust can be determined (the smallest frame is the pixel). For example, here, a frame of up to 1, 2,..., N columns is set in the horizontal direction on the paper with respect to the locus 50 of the laser beam LB displayed on the monitor 20 shown in FIG. The output sum is calculated by the signal processing unit 60, and, for example, a difference D is obtained by, for example, calculating the sum of the output of the Nth row, which is an intermediate frame, and the sum of the outputs before and after the sum as in the following equation (1). Thereby, the difference in illuminance from the adjacent frame is quantified, so that even if the difference in illuminance due to adhesion of dust or the like is minute, it can be detected.列 N column−Σ (N−1) column = D (1) A reference value is provided for the value of the difference D, and when the value of D exceeds the reference value, dust is attached. Assuming that there is a difference in the illuminance, it is presumed that there is a foreign substance at the front and rear positions of the frame of the N rows. The signal processing unit 60 can automatically and automatically process the comparison between the difference D between adjacent frames and the reference value as described above and the evaluation thereof. In addition, the signal processing unit obtains the total output ΣN in each column of the frame 62 in all the regions scanned by the laser beam LB, thereby obtaining the signals shown in FIG.
As shown in (1), the light emission intensity distribution of the beam at each measurement position irradiated with the laser beam LB via the laser optical system 16 can be obtained. As shown in FIG. 5, if the light emission intensity distribution of the laser beam LB is obtained, the state of the change in the light emission intensity can be known at a glance. Can be determined. Here, the frame 62
Is defined as a fixed area, but one pixel, which is the minimum unit, is defined as one area.
Signal processing may be performed as one frame. In this way, even if there is a minute difference in illuminance or small foreign matter is attached, it is possible to determine this.

<< Third Embodiment >> Next, a third embodiment will be described with reference to FIGS. Here, components that are the same as or equivalent to those in the first and second embodiments described above are given the same reference numerals, and descriptions thereof will be simplified or omitted. Although the schematic configuration of the laser optical system inspection apparatus 10 of FIG. 1 is common,
If there is a feature in the added portion or the internal configuration, it will be described each time. In the first and second embodiments described above, the laser beam LB is scanned in the fully lit state as shown in FIG. 4, but in the third embodiment, the laser control unit 14 controls the laser beam LB. By controlling the lighting state of the beam LB to be variable, the laser optical system 16 is controlled.
Is to be inspected for defects. That is, as shown in FIG. 1, the laser optical system 16 has a mirror 40 that reflects the laser beam LB when the scanning end is irradiated with the laser beam LB, and detects the laser beam LB reflected by the mirror 40. And a cycle detection sensor 70 for detecting a scanning cycle. Then, the laser control unit 14
Are a trigger forming unit 72 that forms a trigger based on a synchronization signal input from the cycle detection sensor 70, and a lighting control unit that controls lighting of the laser light source 12 based on the trigger formed by the trigger forming unit 72. 74.

Next, the operation will be described. For example, as shown in FIG. 7, the laser control unit 14 controls to turn on and off five times between a synchronization signal indicating one scan and the next synchronization signal, as shown in FIG. Such a dot pattern 76 is formed, and this can be displayed on the monitor 20 as an image. As a result, the lens 30 and various mirrors 36, 38, 42, 4 constituting the laser optical system
If there is distortion, undulation, or the like in the image 4, the image of the laser beam LB formed at the image forming position is not the original irradiation pattern as shown in FIG. 8, and for example, as shown in FIG. Since a combined pattern 78 and a pattern (not shown) that widens the space between the dot patterns 76 are formed, the radiation pattern displayed on the monitor 20 can be observed only by looking at the distortion or undulation in the laser optical system 16. Defects can be detected. Also,
As shown in FIG. 1, the laser control unit 14 further controls the lighting control unit 74 based on a synchronization signal input from the period detection sensor 70 to select the mirror surface of the polygon mirror 32. A mirror surface selection unit 80 as a possible mirror surface selection unit may be further provided.

When the mirror surface selecting unit 80 in the laser control unit 14 is used, the reflectance of each mirror surface of the polygon mirror 32 is detected in advance by using the signal processing unit 60 or the like, and the reflection of the mirror surface is determined. If there is an error in the image formed due to the difference in the reflectivity, always use the same mirror surface.If there is a mirror surface with a large difference in reflectivity, skip the mirror surface only. Is appropriately selected. If a foreign object is attached to a part of the mirror surface of the polygon mirror 32 or distortion or undulation is detected by the monitor 20 or the signal processing unit 60, the mirror surface selection unit 80 sets the mirror surface. The mirror surface is appropriately selected so as to be used by skipping. Accordingly, since the laser beam LB is scanned using only the appropriate mirror surface of the polygon mirror 32, an appropriate image can always be formed.

[0018]

As described above, according to the first aspect of the present invention, foreign matter adheres to a laser optical system that scans a surface to be irradiated by irradiating a laser beam, and distortion or undulation is caused. It can be inspected by visually observing what has occurred with the image display means. According to the second aspect of the present invention, by adjusting the amount of laser light received by the filter to irradiate the image sensor, it is possible to properly inspect the light receiving output of the image sensor so as not to be saturated. According to the third aspect of the present invention, the adhesion of a foreign substance or the like to the laser optical system is inspected by comparing the illuminance between adjacent divided regions in the scanning direction based on the irradiation data of the laser light to the image sensor. Can be. According to the fourth aspect of the present invention, it is possible to inspect the adhesion of a foreign substance or the like to the laser optical system by obtaining the illuminance distribution of all the divided regions in the scanning direction based on the irradiation data of the laser light to the image sensor. it can. According to the fifth aspect of the present invention, by controlling the lighting pattern of the laser light, the irradiation data of the laser light applied to the image pickup device is visually observed by the image display means, so that the distortion or undulation caused in the laser optical system. Etc. can be inspected. According to the sixth aspect of the present invention, by controlling the lighting of the laser beam, it is possible to select an appropriate mirror surface of the rotary polygon mirror of the laser optical system, so that scanning can be performed while appropriately irradiating the laser beam.

[Brief description of the drawings]

FIG. 1 is a block diagram of a laser optical system inspection apparatus according to a first embodiment.

FIG. 2 is a diagram showing a trajectory of a laser beam displayed as an image on a monitor of the laser optical system inspection apparatus in FIG. 1;

FIG. 3 is a diagram showing a locus of a laser beam displayed on a monitor as an image when a foreign substance is attached to the laser optical system of the laser optical system inspection apparatus in FIG. 1;

FIG. 4 is a timing chart showing a laser beam lighting control state according to the first embodiment.

FIG. 5 is a diagram illustrating a processing procedure of an output of a CCD camera in a signal processing unit of a laser optical system inspection apparatus according to a second embodiment.

FIG. 6 is a diagram of a light emission intensity distribution based on an output of a CCD camera obtained by a signal processing unit of a laser optical system inspection device according to a second embodiment.

FIG. 7 is a timing chart showing a laser beam lighting control state according to a third embodiment.

8 is a diagram illustrating an example of a display image on a monitor when the laser beam lighting control of FIG. 7 is performed.

9 is a diagram showing an example of a display image on a monitor when a laser optical system has distortion when the laser beam lighting control of FIG. 7 is performed.

[Explanation of symbols]

10 laser optical system inspection device, 12 laser light source,
14 laser control unit (lighting control means), 16 laser optical system, 18 CCD camera (image pickup device), 19
Slide stage (moving means), 20 monitors (image display means), 22 filters, 60 signal processing section (detecting means), 72 trigger forming section (part of lighting control means), 74 lighting control section (one of lighting control means) Department),
80 Mirror surface selector (mirror surface selector, part of lighting control means), LB laser beam (laser light)

Claims (6)

[Claims] 1. A laser optical system inspection apparatus for inspecting a laser optical system that scans by irradiating a laser beam from a laser light source onto a surface to be irradiated, wherein an image forming position of the laser beam irradiated with the laser beam is provided. An image sensor that detects a laser beam in a predetermined irradiation area irradiated through the laser optical system, a moving unit that moves the image sensor in a scanning direction of the laser beam, A laser optical system inspection apparatus, comprising: an image display unit that displays an image of laser beam irradiation data. 2. The laser optical system according to claim 1, further comprising a filter arranged between the laser optical system and the image sensor for adjusting an amount of laser light received on the image sensor. Inspection equipment. 3. Irradiation data taken in when scanning while continuously irradiating the image pickup device with laser light is divided into a plurality of regions in the scanning direction of laser light, and the illuminance of adjacent divided regions is compared. The laser optical system inspection apparatus according to claim 1, further comprising a detection unit configured to detect a change in illuminance. 4. Irradiation data obtained when scanning while continuously irradiating the image pickup device with laser light is divided into a plurality of regions in the scanning direction of laser light, and illuminance of all divided regions is obtained. The laser optical system inspection device according to claim 1, further comprising a detection unit configured to detect a laser beam. 5. A lighting control means for controlling lighting and extinguishing of a laser light emitted from the laser light source, wherein the laser light emitted in a predetermined lighting pattern by the lighting control means is applied to the image pickup device. 2. The irradiation data is displayed as an image on the image display means.
Or the laser optical system inspection device according to 2. 6. The laser optical system has a rotary polygon mirror for scanning a laser beam, and the lighting control means performs a lighting control in synchronization with the rotation of the rotary polygon mirror to select a mirror surface. The laser optical system inspection device according to claim 5, further comprising: