JPH03180812A - Optical scanner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical scanning device that can be suitably used as an optical scanning unit in an electrophotographic image recording apparatus.

Conventional technology An optical scanning device in an electrophotographic image recording apparatus usually uses a rotating polygon mirror, as disclosed in Japanese Patent Application Laid-open No. 55-129313, etc., and its rotation axis is The laser beam is irradiated from the perpendicular direction, and the rotating polygon is configured so that as the polygon rotates, the laser beam is sequentially reflected from each reflective surface on its outer periphery for optical scanning.

An example of an optical scanning device using a rotating polygon mirror will be explained with reference to FIG. 3. Laser light emitted from a laser light source 21 is converted into a parallel beam light via a collimator lens 22 and a cylindrical lens 23, and is converted into a parallel beam of light that is transmitted through a rotating polygon mirror. The reflected light from the reflective surface on the outer periphery is scanned in a predetermined angle range as the rotating polygon mirror 24 rotates, and the reflected light can be rotated around the axis via the fθ lens 25 and the cylindrical lens 26. An electrostatic latent image of an image to be formed on the photoreceptor drum 27 is formed using modulated laser light that is scanned on the outer peripheral surface of the photoreceptor drum 27 in its axial direction. In order to detect a reference position for setting the image formation start position in the optical scanning direction on the photoreceptor drum 27, an optical sensor 28 is disposed near the end of the photoreceptor drum 27 on the optical scanning start end side. There is.

As is well known, the electrostatic latent image formed on the photosensitive drum 27 is developed with toner in a developing device and then transferred onto a sheet of paper, thereby forming a predetermined image on the sheet of paper.

Problem to be Solved by the Invention However, in the above-mentioned device in which the reference position for starting image formation is detected by the optical sensor 28 disposed near the photoreceptor drum 27, there is a lens in front of the optical sensor 28. , etc., and reflective optical systems are often required, resulting in high costs and the problem that it takes time and effort to adjust the position so that the scanning light is properly incident on the optical sensor 28. When the light source 21 is not emitting light, the reference position cannot be detected, and the detection output changes due to variations in the output of the laser light source 21, causing problems such as detection errors and detection errors in the reference position. there were.

In view of the above-mentioned conventional problems, the present invention enables reliable detection of the reference position for starting operations such as image formation, regardless of the light emitting state of the light source, and has a simple configuration and does not require the effort of adjustment. The purpose of the present invention is to provide an optical scanning device.

Means for Solving the Problems In order to achieve the above object, the present invention includes: a light source; a reflecting means having a reflecting surface tilted with respect to the optical axis on its tip axis and rotatable between the optical axes; The present invention is characterized in that it includes a rotating body that rotates together with the reflecting means and has a detection mark formed on its outer periphery, and a means for detecting the detection mark that is arranged opposite to the outer periphery of the rotating body.

According to the above configuration of the present invention, the light emitted from the light source is reflected by the reflecting surface of the reflecting means and deflected, and as the reflecting means rotates, the reflected light moves rotationally between the optical axes. , one line of light is scanned every rotation of the reflecting means, and therefore, the fixed rotational position of the reflecting means can be determined by using the detecting means to detect a detection mark on the outer periphery of the rotating body that rotates together with the reflecting means. This detection position can be used as a reference position to set an operation start position for image formation, etc.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

In FIG. 1, l is a laser light source such as a semiconductor laser, 2
is a collimator lens, and 3 is a rotating reflector.The optical axes of the laser light source 1 and the collimator lens 2 are aligned, and the rotational axis of the rotating reflector 3 is aligned with the optical axis, so that the laser beam emitted from the laser light source 1 is The collimator lens 2 converts the light into parallel light and makes it incident on the rotational axis of the rotating reflecting mirror 3. As shown in FIG. 2, the rotating reflector 3 is formed with a reflective surface 3a that is inclined at an angle of 45° with respect to the optical axis on the optical axis, and the incident laser beam is tilted with respect to the optical axis. The emitted light is deflected in the vertical direction and emitted, and as the rotating reflecting mirror 3 rotates, the emitted light is emitted as scanning light that rotates in the rotational direction on a plane perpendicular to the optical axis. The scanning light is configured to be irradiated onto the outer circumferential surface of the photoreceptor drum 5 via the fθ lens 4. The photosensitive drum 5 is disposed so that its axis is parallel to the scanning direction of the scanning light, and is configured to be rotatably driven in a fixed direction in synchronization with the scanning of the scanning light.

A rotary disk 6 is concentrically and integrally provided at the lower part of the rotary reflecting mirror 3, and a detection mark 7 made of a thin line extending in the axial direction is formed at an appropriate location on the outer peripheral surface of the rotary disk 6. Further, a reflective optical sensor 8 for detecting the detection mark 7 is arranged opposite to the outer peripheral surface of the rotating disk 6. This reflective optical sensor 8 is installed on a substrate 9 that supports the rotating reflecting mirror 3, the rotating disk 6, and its driving means.

Next, the optical scanning unit 10 for the photoreceptor drum 5
A specific example configured as follows will be explained with reference to FIG.

The optical scanning unit) 10 is unitized by a cylindrical support frame 11. That is, the mounting plate 12 on which the laser light source l is attached is fixed to the upper end of this cylindrical support frame 11,
A collimator lens 2 is fitted into a mounting hole 13 having a step 14 formed on the inner periphery of an intermediate portion in the vertical direction, and a substrate 9 is fixed to a downward step 15 formed at the bottom. A drive motor 16 such as a flat motor is installed on the lower surface of this substrate 9, and a rotating reflector 3 and a rotating circle Fi6 are attached to the output shaft of the drive motor 16 that penetrates the substrate 9 and protrudes upward.
are mounted concentrically, and a reflective optical sensor 8 is placed on the base vi9 at the side of the rotating disk 6. The mounting plate 12 and the substrate 9 are positioned so that the optical axes of the laser light source 1 and the collimator lens 2 are concentric with the axis of the drive motor 16, and appropriate positioning means such as positioning pins (not shown) are used for this purpose. ) is provided. Further, on the peripheral wall of the cylindrical support frame 11, an optical axis and a reflective surface 3 are provided.
The fθ lens 4 is disposed at a position on a horizontal plane passing through the intersection with a.

According to the above configuration, a modulated laser beam is output from the laser light source 1, and the rotating reflecting mirror 3 is rotated to repeatedly scan the outer peripheral surface of the photoreceptor drum 5 in the axial direction with the laser beam at high speed. At the same time, by rotating the photosensitive drum 5 about its axis, an electrostatic latent image of a predetermined image can be formed on the outer peripheral surface of the photosensitive drum 5. At this time, the image formation start position in each optical scan may be set using the rotational position of the rotary reflecting mirror 3 at the time when the detection mark 7 is detected by the reflective optical sensor 8 as a reference position. That is, after a certain period of time has elapsed after the detection signal from the reflective photosensor 8 is output, the laser light source 1 is modulated and driven based on predetermined image data, so that the photoreceptor drum 5 is completely covered with each previous scan. Can form synchronized images. In addition to the modulation drive period of the laser light output from the laser light source 1,
By setting the operating period of the laser light source 1 only to the period during which the photosensitive drum 5 is scanned based on the signal from the reflective sensor 8, the laser light source 1 can be operated only during the effective period, and its lifespan can be reduced. It can be made longer.

According to the above configuration, since the reference position is detected by detecting the detection mark 7 with the reflective optical sensor 8, the reference position can be detected even when the laser light source I is not emitting light. Further, there is no possibility that a detection error or a detection error of the reference position will occur due to variations in the output of the laser light source 1.

In addition, it has a simple configuration in which the rotating disk 6 and the reflective optical sensor 7 are provided on the substrate 9, and the installation position of the reflective optical sensor 8 and a predetermined position on the photoreceptor drum 5 in the axial direction are different from each other. Just by detecting the correspondence, the rotating disk 6, the detection mark 7,
There is no need to adjust the position of the reflective optical sensor 8, and assembly and adjustment can be easily performed.

Furthermore, as shown in FIG. 2, by unitizing the entire optical scanning unit 10, assembly, adjustment, and maintenance management become dramatically easier.

Effects of the Invention According to the present invention, one line of light scanning is performed for each rotation of the reflecting means. The reference position can be detected by detecting the detection mark on the outer periphery of the rotating body that rotates with the light source. Therefore, the reference position can be reliably detected regardless of the light emission state of the light source, and a separate optical system for detection is not required. It is easy to configure without having to
Furthermore, there is no need for time and effort for position adjustment, which provides great effects.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an optical scanning device according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing a specific example of the same configuration, and FIG. 3 is a schematic configuration of a conventional optical scanning device. FIG. Laser light source Rotating reflector Rotating disc detection mark Reflective optical sensor Optical scanning unit

Claims (1)

[Claims] A light source, a reflecting means having a reflecting surface inclined with respect to the optical axis on the optical axis and rotatable around the optical axis, and a rotating body that rotates together with the reflecting means and has a detection mark formed on its outer periphery. 1. An optical scanning device comprising: a detecting means for detecting the detection mark disposed opposite to an outer circumferential portion of a rotating body.