JPH07218854A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To prevent the degradation of the picture quality accompanied with the dirt of a rotating polygon mirror or the change of the quantity of light emitted from a semiconductor laser. CONSTITUTION:A rotating polygon mirror 1 is made of a transparent material, and each reflection face 1b consists of a semitransparent film. An optical sensor 3 is built in the rotating polygon mirror 1 and detects transmitted light from the semitransparent film. A semiconductor laser 4 is provided with an emitted beam quantity controller which controls the quantity of emitted beam based on the output of the optical sensor 3, and the quantity of beam emitted from the semiconductor laser is controlled to prevent the degradation of the picture quality if each reflection face is dirtied by dust or the like or the quantity of emitted beam from the semiconductor laser itself is changed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic apparatus used for laser printers, laser facsimiles and the like.

[0002]

2. Description of the Related Art In an electrophotographic apparatus used for a laser printer, a laser facsimile or the like, as shown in FIG. 5, a laser beam L ₁ generated from a semiconductor laser S is collimated by a collimator lens (not shown) and then cylindrical. The light is condensed linearly by the lens C and is irradiated onto each mirror surface 101a on the outer peripheral surface of the rotary polygon mirror 101. The laser beam L ₂ deflected by the rotation of the rotary polygon mirror 101 is imaged on the photoconductor on the rotary drum D via the imaging lens F and the folding mirror M, and the main scanning by the rotation of the rotary polygon mirror 101 and the rotary drum D. An electrostatic latent image is formed by sub-scanning by rotation of the. Further, a part of the laser light L ₂ deflected by the rotary polygon mirror 101 is reflected by the detection mirror N to the light receiving end of the optical fiber G, and is input to the semiconductor laser S as a write start signal. The rotary polygon mirror 101,
The imaging lens F, the folding mirror M, the detection mirror N, the optical fiber G, etc. are housed in the optical box E, and the semiconductor laser S is mounted on one side wall of the optical box E. Further, on the bottom wall of the optical box E, there is provided an extraction window W for the laser light L ₃ reflected from the folding mirror M toward the rotary drum D.

The drive system for rotating the rotary polygon mirror 101 is
As shown in FIG. 6, the rotor 104 integrated with the shaft 103 supported by the bearing 105 and the housing 1 of the bearing 105.
The rotor 1 comprises a stator 106 fixed to 05a.
04 and the stator 106 constitute a motor that rotationally drives the rotary polygon mirror 101. That is, the magnet 104a of the rotor 104 and the coil 106a of the stator 106 are disposed so as to face each other, and the rotary polygon mirror 101 is pressed against the rotor 104 by the leaf spring 102 and integrally coupled to the rotor 104, so that the coil 106a of the stator 106 is When a current is supplied from a drive circuit (not shown) on the substrate 107 on which the shaft is mounted, the shaft 103, the rotor 104, and the rotary polygon mirror 101 rotate integrally.

Further, the semiconductor laser S has a light amount adjusting device for adjusting the light emission amount of the laser light L ₁ according to the required light amount of the laser light imaged on the photosensitive member of the rotary drum D, that is, the exposure light.

[0005]

However, according to the above-mentioned prior art, a means is provided for detecting when the dust and the like in the air adheres to the respective mirror surfaces of the rotary polygon mirror and the reflectance decreases. Therefore, it is unavoidable that the light quantity of the exposure light, that is, the exposure quantity of the photosensitive member is changed by the contamination of the mirror surface and the image quality of the electrophotographic apparatus is deteriorated.

Further, when the mirror surface of the rotary polygon mirror is significantly contaminated, it is common to replace the whole rotary polygon mirror with a new one, and in order to reduce the frequency of replacement, the mirror surface of the rotary polygon mirror is contaminated. Although measures such as providing a cover for preventing the above are made, it is not preferable because it causes an increase in the size of the device and the replacement work of the rotary polygon mirror is complicated.

The present invention has been made in view of the above problems of the prior art, and it is possible to prevent deterioration of image quality due to contamination of the mirror surface of the rotating polygon mirror or change in the light emission amount of the semiconductor laser. It is intended to provide a photographic device.

[0008]

To achieve the above object, an electrophotographic apparatus of the present invention comprises a rotary polygon mirror having at least one reflecting surface on its outer peripheral surface, and a light source for irradiating the reflecting surface with illumination light. And a photoconductor exposed by the reflected light from the reflecting surface, and a detection means for detecting the amount of the reflected light.

The reflecting surface is a semi-transmissive film, and the detecting means has an optical sensor for detecting the illuminating light radiated to the reflecting surface that has transmitted the illuminating light. Is preferably configured to detect.

The optical sensor may be incorporated in the rotary polygon mirror.

Further, it is preferable that the light source is provided with a light emission amount adjusting device for adjusting the light emission amount based on the output of the detecting means.

Further, it is preferable to have a cleaning means for cleaning the reflecting surface.

[0013]

The amount of reflected light of the illumination light applied to the reflecting surface of the rotary polygon mirror is detected by the detecting means, and the amount of exposure of the photoconductor is detected based on the output, and the amount of light emitted from the light source is adjusted. By cleaning the reflective surface, it is possible to prevent deterioration of image quality due to contamination of the reflective surface or a change in the light emission amount of the light source.

The reflecting surface is a semi-transmissive film, and the detecting means has an optical sensor for detecting the illuminating light radiated to the reflecting surface that has passed through the light sensor, and the light quantity of the reflected light is based on its output. If it is configured to detect, the amount of light reflected by the reflecting surface can be detected with high accuracy. Further, if the optical sensor is incorporated in the rotary polygon mirror, a new space for installing the detecting means is not required, so that the device can be prevented from becoming large and complicated. Further, if the light source is provided with a light emission amount adjusting device that adjusts the light emission amount based on the output of the detection unit, the light emission amount of the light source is automatically adjusted based on the output of the detection unit to prevent deterioration of image quality. be able to. If there is a cleaning means for cleaning the reflecting surface, when the reflecting surface is contaminated, it can be cleaned by the cleaning means to prevent changes in the exposure amount of the photoconductor.

[0015]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is an explanatory view for explaining the main part of one embodiment, which has a regular hexagonal columnar main body 1a made of a transparent material, and six reflecting surfaces 1b on the outer peripheral surface thereof. A rotary polygon mirror 1 having a shaft 2 and a shaft 2 integrally connected to the rotary polygon mirror 1.
And a semiconductor laser 4 which is a light source for irradiating the outer peripheral surface of the rotary polygon mirror 1 with laser light L which is illumination light. Each reflection surface 1b of the mirror 1 is composed of a semi-transmissive film that transmits a part of the light irradiated on the mirror 1 and reflects the remaining light, and the optical sensor 3 is one of the six reflection surfaces 1b. It is arranged so as to receive the transmitted light transmitted through and detect the amount of light. Further, the semiconductor laser 4 includes a detection unit that detects the light amount of the reflected light of the reflecting surface 1b based on the output of the optical sensor 3 and a light emission amount adjustment device (not shown) that controls the light emission amount of the semiconductor laser 4 based on the output. I have it.

The rotating polygon mirror 1 is rotated by a motor which is composed of a rotor (not shown) integrated with the shaft 2 and a stator on a substrate which is integrated with a casing (not shown) for supporting the rotating polygon mirror 1 and the semiconductor laser 4. The casing supports an imaging lens system, a reflection mirror, an optical fiber, a folding mirror, etc., which are not shown.

Laser light L emitted from the semiconductor laser 4
Part of the light is transmitted through each reflection surface 1b, and the rest is deflected and scanned by the rotation of the rotary polygon mirror 1, and an image is formed on a photoconductor of a rotating drum (not shown) through the image forming lens system and the folding mirror, and the light is exposed.

Since the rotating speed of the rotary polygon mirror 1 reaches 10,000 times per minute and is extremely high, friction with the surrounding air is large and dust in the air is reflected on each reflecting surface 1b. Adheres to the surface and the reflectance decreases. Such a decrease in the reflectance of each reflecting surface 1b of the rotary polygon mirror 1 or a change in the amount of light emitted from the semiconductor laser 4 itself changes the amount of light reflected by each reflecting surface 1b.
As a result, the exposure amount of the photoreceptor changes and the image quality deteriorates.
Therefore, the light amount of the reflected light of each reflection surface 1b is detected based on the light amount of the transmitted light detected by the optical sensor 3, and the light emission amount of the semiconductor laser 4 is adjusted by controlling the light emission amount adjusting device described above. It compensates for changes in the exposure amount of the photoconductor and realizes stable high image quality.

FIG. 2 illustrates a process of appropriately controlling the exposure amount of the photoconductor by controlling the light emission amount of the semiconductor laser 4 based on the output of the optical sensor 3. In step S1, the semiconductor laser 4 is controlled. Light emission is started, the light amount of the reflected light is detected based on the output of the optical sensor 3 in step S2, the exposure amount of the photoconductor is detected based on this, and the exposure amount is set to a reference value stored in advance in step S3. On the other hand, it is determined whether or not the value is an appropriate value within an error range of, for example, ± 10%. If the value is an appropriate value, an image forming cycle such as copying by the electrophotographic apparatus is started in step S4. If the exposure amount is not the proper value, it is determined in step S5 whether it is larger or smaller than the proper value. If it is larger than the proper value, the light emission amount of the semiconductor laser 4 is reduced in step S6 to be smaller than the proper value. If it is smaller, the light emission amount of the semiconductor laser 4 is increased in step S7 and the process returns to step S1.

In this embodiment, the amount of laser light transmitted through each reflecting surface of the rotating polygon mirror is detected by an optical sensor incorporated in the rotating polygon mirror, so that the reflectance decreases due to contamination of each reflecting surface and the semiconductor. Since the change in the laser emission amount is detected, the change in the exposure amount of the photoconductor on the rotating drum is detected quickly and accurately, the emission amount of the semiconductor laser is adjusted, and the exposure amount is maintained at an appropriate value. be able to. Therefore, even if each reflecting surface of the rotary polygon mirror is contaminated or the amount of light emitted from the semiconductor laser changes, the density of the image does not change due to this. As a result, a stable and highly accurate image can be obtained.

When a decrease in the amount of light reflected by the rotary polygon mirror 1 is detected by the output of the optical sensor 3, it is determined that this is mainly due to the contamination of each reflecting surface 1b of the rotary polygon mirror 1. If so, the semiconductor laser 4
Instead of adjusting the amount of light emitted from each of the reflecting surfaces 1 of the rotary polygon mirror 1, a wiper 5 as a cleaning means as shown in FIG. 3 is used.
It is desirable to clean b.

The wiper 5 comprises a cleaning pad 5b held by an arm 5a, and the cleaning pad 5b is a rotary polygon mirror 1.
4 has a width that is the same as or slightly wider than the width of each reflecting surface 1b in the circumferential direction, and is brought into contact with each reflecting surface 1b by the robot, not shown, manually or in the axial direction of the rotary polygon mirror 1, as shown in FIG. Sliding to removes dust and the like adhering to each reflecting surface 1b.

The cleaning of the reflecting surfaces 1b by the wiper 5 is not limited to the case where the contamination of the reflecting surfaces 1b is detected by the optical sensor 3, but is constantly performed before the electrophotographic apparatus is started. Needless to say, if it is done, the reliability of the electrophotographic apparatus will be improved and it will contribute to higher efficiency.

Further, since the optical sensor 3 is incorporated in the rotary polygon mirror 1 and a new space for installing the optical sensor 3 is not required, there is no fear that the device becomes large or complicated.

Further, it is possible to provide a plurality of optical sensors 3 and individually detect contamination of some or all of the six reflecting surfaces 1b of the rotary polygon mirror 1.

[0027]

Since the present invention is constructed as described above, it has the following effects.

It is possible to prevent a change in the light emission amount of the photoconductor due to the contamination of the reflecting surface of the rotating polygon mirror or a change in the light emission amount of the semiconductor laser, and to realize stable high image quality.

By incorporating an optical sensor for detecting the amount of light reflected by the reflecting surface into the rotary polygon mirror, a compact and simple electrophotographic apparatus can be realized.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a main part of one embodiment.

FIG. 2 is a sequence diagram showing a process of detecting the light amount of exposure light and adjusting the light emission amount of a semiconductor laser.

FIG. 3 is a plan view showing a wiper that cleans a reflecting surface of a rotary polygon mirror.

4A and 4B are diagrams for explaining the operation of the wiper of FIG. 3, in which FIG. 4A is a state immediately before the wiper is brought into contact with the reflecting surface of the rotating polygon mirror, and FIG. FIG. 6 is a sectional view showing a state in which the wiper is in contact with the upper end, and a state in which the wiper is slid in the axial direction of the rotary polygon mirror.

FIG. 5 is an explanatory diagram illustrating the entire electrophotographic apparatus.

6 is a cross-sectional view showing a driving unit of the rotary polygon mirror in FIG.

[Explanation of symbols]

 1 rotating polygon mirror 1b reflecting surface 2 axis 3 optical sensor 4 semiconductor laser 5 wiper

Claims (5)

[Claims] 1. A rotating polygon mirror having at least one reflecting surface on its outer peripheral surface, a light source for irradiating the reflecting surface with illumination light, and a photoconductor exposed by the reflected light from the reflecting surface.
An electrophotographic apparatus having a detection unit that detects the amount of the reflected light. 2. The reflecting surface is a semi-transmissive film, and the detecting means is
It has a photosensor which detects the illumination light which permeate | transmits this among the illumination light with which the said reflective surface was irradiated, and it is comprised so that the light quantity of reflected light may be detected based on the output. 1. The electrophotographic apparatus according to 1. 3. The electrophotographic apparatus according to claim 2, wherein the optical sensor is incorporated in the rotary polygon mirror. 4. The electrophotographic apparatus according to claim 1, wherein the light source includes a light emission amount adjusting device that adjusts the light emission amount based on the output of the detecting means. 5. The electrophotographic apparatus according to claim 1, further comprising cleaning means for cleaning the reflecting surface.