JPH0511200A - Scanning optics - Google Patents

Abstract

(57) [Abstract] [Purpose] To shorten the length of the reflecting member of the scanning optical device. A mirror 11 is held by a mirror holding plate 13 via a mirror holding spring 12, and a laser beam L scanned by a polygon mirror passes through a hole 13a provided in the mirror holding plate 13 and 12d provided in the plate spring 11. Then, the light is detected by the photodetector 10 provided at the rear.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning optical device for a laser beam printer or the like, which scans a photosensitive member with a light beam to form an image on the photosensitive member.

[0002]

2. Description of the Related Art Conventionally, as described in Japanese Utility Model Laid-Open No. 63-122317, a scanning optical device in a laser beam printer or the like is provided with a non-deposited region in a part of a reflecting mirror and transmits the light. The photodetector detects a part of the scanning light flux.

FIG. 3 is a perspective view showing the structure of a conventional scanning optical device of a laser beam printer. A radial light beam emitted from the semiconductor laser light source 1 is condensed into a parallel light beam by the collimator lens 2, reflected on each surface of the polygon mirror 3 rotating in the arrow direction at a constant rotation speed, and scanned. After the light flux scanned at a constant angular velocity passes through the fθ lens systems 4 and 5, most of the scan light flux is reflected by the mirror 6 and condensed on the surface of the photoconductor drum 7, and is constant in the arrow direction. And a scanning line is formed on the surface of the photosensitive drum 7. A part of the scanning light flux is transmitted through the mirror 6 through the non-vapor-deposited region 6a provided on one end side of the mirror 6 for each scanning, and is placed at almost the focal position of the fθ lens systems 4 and 5. A photodetector 1 including a lens 8, an optical fiber 9 and a photosensor (not shown)
Detected by 0.

The photodetector 10 functions to determine the start of the recording signal, and a control circuit (not shown) generates a signal for starting the recording signal after a predetermined time has elapsed since the light was received. With this signal,
The semiconductor laser light source 1 is modulated brightly and darkly according to the recording signal from the modulation circuit, and the photosensitive drum 7 rotates in the direction of the arrow to form an electrostatic latent image of a recorded image on the photosensitive drum 7.

[0005]

However, in the scanning optical device as in the above-mentioned conventional example, the mirror 6 is formed in addition to the minimum necessary region necessary for forming an image, without vapor deposition at the end thereof. Since the transparent region 6a must be provided, the following drawbacks occur.

(1) The number of man-hours for manufacturing the mirror 6 increases.
In other words, when vapor-depositing copper or aluminum on the glass material,
Part of the mask must be masked, and the mirror 6 is oriented in the longitudinal direction. Therefore, care must be taken during assembly.

(2) Since the mirror 6 becomes long, it is disadvantageous to set the natural frequency. In general, the natural frequency of the mirror 6 should be set as high as possible so that it does not resonate with the vibration of the polygon mirror 3 and the vibration of other driving units, and the vibration of the mirror 6 does not affect the image. desirable. The vibration of the mirror 6 can be grasped as bending vibration of the beam, but since the natural frequency decreases in inverse proportion to the square of the length of the mirror 6, it is disadvantageous that the mirror 6 becomes longer than necessary.

An object of the present invention is to solve the above-mentioned drawbacks and to provide a scanning optical device in which the length of the reflecting member is set to the minimum necessary length.

[0009]

A scanning optical device according to the present invention for achieving the above object comprises a scanning means for scanning a light beam, a reflecting member for reflecting the light beam scanned by the scanning means, A scanning optical device comprising: a photoconductor that receives a scanning light beam reflected by a reflecting member to record an image; and a detecting unit that receives a part of the scanning light beam and detects the light beam for each scanning, The reflecting member is arranged between the means and the detecting means, and a passing portion for passing a part of the scanning light flux is formed in a holding means for holding an end portion of the reflecting member.

[0010]

In the scanning optical apparatus having the above-described structure, the reflecting member is made to have a minimum length necessary for image formation, and a groove or a hole is formed in the member holding one end of the reflecting member to allow a part of the scanning light beam to pass therethrough. The light beam is detected for each scanning by the detection means arranged ahead of the light beam.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. The same reference numerals as those in FIG. 3 indicate the same members. FIG. 1 is a perspective view of a main part, and FIG. 2 is a schematic configuration diagram of a laser beam printer. In FIG. 1, the mirror 11, which is a reflecting member, is held by a mirror holding plate 13 via a mirror holding spring 12. The mirror holding plate 13 is fixed to a stay 14 shown in FIG. 2, which is a structure of the laser beam printer main body. The mirror holding plate 13 is provided with a hole 13a, and the photodetector 10
The laser beam L which is to be detected by means of is able to pass through. Further, the mirror holding plate 13 is provided with a hole 13b into which the end of the mirror 11 is inserted, so that one end of the mirror 11 can be held and the angular position of the mirror 11 can be positioned and adjusted. There is. That is,
The end of the mirror 11 is positioned by two points, a protrusion 13c provided in the hole 13b of the mirror holding plate 13 and a tip of a screw 15 screwed into the screw hole of the bent and raised portion 13d. Similarly, the opposite end of the mirror 11 is positioned by a mirror holding plate (not shown) and one point by a screw, and the surface of the mirror 11 is adjusted by three points as a whole.

Mirror holding spring 12 curved in a U shape
Plays a role of elastically abutting the mirror 11 on the projection 13 c and the tip of the screw 15, and the mirror holding spring 12 is fixed to the mirror holding plate 13 by the screw 16. The apex of the curved portion of the mirror holding spring 12 is divided into two vertices 12a and 12b, and a groove portion 12c is formed between them so that the mirror 11 can be pressed by following the push and pull of the screw 15. The mirror holding spring 12 is provided with a hole 12d,
The laser beam L that has passed through the hole 13a of the mirror holding plate 13 can pass through the hole 12d and the groove 12c.

Semiconductor laser light source, collimator lens,
The laser beam L scanned and condensed by the polygon mirror 3 and the fθ lens group passes through the hole 13a of the mirror holding plate 13, the hole 12d of the mirror holding spring 12 and the groove 12c to reach the rear side, and the laser beam L is almost focused. It is detected by the photodetector 10 placed in position. This photodetector 10
Has a function of determining the start of the recording signal, and a control circuit (not shown) generates a signal for starting the recording signal after a predetermined time has elapsed since the light was received. With this signal, the semiconductor laser light source is modulated light and dark according to the recording signal from the modulation circuit, and an electrostatic latent image of a recorded image is formed on the photosensitive drum 7.

[0014]

As described above, in the scanning optical device according to the present invention, since the light transmitting portion is provided in the holding means for holding the reflecting member without providing the transmitting portion in the reflecting member, the length of the reflecting member is increased. The advantages are that the length can be shortened and the reflection member can be stably held.

[Brief description of drawings]

FIG. 1 is a perspective view of a main part.

FIG. 2 is a schematic sectional view of a laser beam printer main body.

FIG. 3 is a perspective view of a conventional scanning optical device.

[Explanation of symbols]

10 Photodetector 11 mirror 12 Mirror holding spring 13 Mirror holding plate

Claims (2)

[Claims] 1. A scanning unit that scans a light beam, a reflecting member that reflects the light beam scanned by the scanning unit, a photoconductor that receives the scanning light beam reflected by the reflecting member and records an image, In a scanning optical device including a detection unit that receives a part of a scanning light beam and detects the light beam for each scanning, the reflecting member is arranged between the scanning unit and the detecting unit, and an end portion of the reflecting member is disposed. A scanning optical device, characterized in that a holding portion for holding is formed with a passage portion for passing a part of the scanning light beam. 2. The angular position of the reflecting member is positioned by three points of the holding means, and one end side of the reflecting member through which the light beam detected by the detecting means passes is defined as two points out of the three points. The scanning optical device according to claim 1, wherein the scanning optical device is adjusted by the following method.