JP2000193902A - Writing optical device - Google Patents

Abstract

(57) [Problem] To provide an inexpensive writing optical device capable of ensuring the tightness of a polygon scanner housing with a small number of parts. SOLUTION: In a writing optical device in which a storage section of a deflection scanning means comprising a polygon scanner 1 is required to be hermetically sealed for soundproofing and dustproofing, openings 7 and 8 are secured as an optical path of the laser light L, and A shielding member 4 that covers the polygon scanner 1 is provided, and an opening 8 that is an optical path of reflected light is closed by an fθ lens. Similarly, the opening 7 into which the laser beam L is incident may be closed by a cylindrical lens 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a writing optical device containing various optical parts for providing an optical path of a laser beam, and more particularly to a polygon for deflecting a laser beam emitted from a light source by a rotating polygon mirror. The present invention relates to a writing optical device that houses a scanner covered by a shielding member.

[0002]

2. Description of the Related Art As a writing optical device of an image forming apparatus such as a laser printer or a copying machine, a device using a so-called polygon scanner which deflects a laser beam from a light source by a rotating polygon mirror is well known. However, this polygon scanner always has problems of soundproofing and dustproofing. At present, especially high speed is required,
As the rotation speed of the polygon scanner increases, soundproofing measures such as a polygon motor have become indispensable.

[0003] As an apparatus for soundproofing and dustproofing a polygon scanner, for example, in an apparatus disclosed in Japanese Patent Application Laid-Open No. Hei 7-261107, a shielding cover is provided inside a wall of a housing which partitions a portion for accommodating the polygon scanner. The housing wall and the shielding cover are provided with an entrance opening through which the laser light from the light source is incident on the polygon scanner and an emission opening through which the reflected light from the polygon scanner passes. Shielding glass is attached to each opening to seal the polygon storage section.

[0004]

However, in the above-mentioned conventional apparatus, a shielding glass is attached to each of the entrance-side opening and the exit-side opening to the polygon scanner storage section which is separated from other optical components. Although the tightness of the polygon scanner housing is improved, the more optical components are used, the more the optical performance such as power loss may be degraded.

SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive writing optical device in which the number of components is reduced while ensuring the same hermeticity of the polygon scanner housing as that of the related art.

[0006]

According to the present invention, there is provided a writing optical apparatus which deflects a laser beam from a light source by a rotating polygon mirror, and which covers the deflecting scanning means and which is provided with the laser beam. In a writing optical device having a shielding member provided with an opening as an optical path of light, an opening through which reflected light from the deflection scanning unit is emitted is closed by an fθ lens.

[0007] Alternatively, a configuration may be adopted in which an opening for allowing laser light from the light source to enter the deflection scanning means is closed by a cylindrical lens.

Further, the cylindrical lens is fitted into a lens holder, and the lens holder is slidably fitted into the opening, and the cylindrical lens is moved along the optical axis with the opening closed. It can be configured to be freely movable in the direction. Further, the lens holder,
It is preferable that a seal member is provided between the opening and the periphery.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a top view showing the configuration of a first embodiment of a writing optical device according to the present invention, and FIG. 2 is a sectional view of the device shown in FIG. The deflection scanning means is a regular hexahedral mirror (hereinafter, referred to as a “polygon mirror”) rotated by a motor.
The polygon scanner 1 is disposed in a polygon storage unit 3 integrally formed with a housing 2. The polygon storage unit 3 includes a partition wall 4 as a shielding member, a cover 5 covering the upper surface of the housing, and an elastic sealing member 6 attached to the cover 5 and in close contact with the partition wall 4. The optical path of the laser beam L is secured by the entrance side opening 7 and the exit side opening 8.

The polygon storage unit 3 has an upper surface covered by a cover 5 and an elastic sealing member 6, an entrance opening 7 of the partition wall 4 by an entrance shielding glass 9, and an exit opening 8 by an fθ lens 10. Respectively, and the inside is a closed space. That is, in the present embodiment, the fθ lens 10 itself is adhered to the partition wall 4 from the outside of the opening 8 on the emission side so as to constitute a part of the sealing means.

The laser light L emitted from the LD unit 11 as a light source passes through the cylindrical lens 12 and then passes through the shielding glass 9 closing the opening 7 on the incident side of the polygon housing 3. Polygon scanner 1
Are reflected by the rotating polygon mirror and are deflected and scanned in a predetermined direction. Lens 10 is positioned with respect to the opening 8 on the emission side such that the laser beam L scanned by the polygon scanner 1 is imaged at a predetermined position on the photoconductor surface (not shown).

FIG. 3 shows a second embodiment of the writing optical device according to the present invention.
FIG. 4 is a top view showing the configuration of the embodiment, and FIG.
It is -B sectional drawing. In the second embodiment, a cylindrical lens 12 is used for the sealing means instead of the fθ lens 10.

In this case, the opening 7 on the incident side is formed by a partition wall extending integrally and continuously to the installation position of the cylindrical lens 12, and the cylindrical lens 12 itself is replaced with the opening 7 instead of the incident side shielding glass. Adhered to the end face. The laser light L emitted from the LD unit 11 passes through the cylindrical lens 12 closing the entrance side opening 7 of the polygon storage unit 3 and reaches the mirror surface of the polygon scanner 1. The exit-side opening 8 is closed by the exit-side shielding glass 16, and the fθ lens 10 is independently disposed outside the housing 3.

FIG. 5 is a sectional view showing the configuration of the writing optical device of the third embodiment when the position of the cylindrical lens 12 can be adjusted. In this case, a prismatic lens holder 13 is fitted into the opening 7 on the incident side so as to be able to advance and retreat in the optical axis direction, and the cylindrical lens 12 is adhered to the inner wall of the lens holder 13 so as not to form a gap. Fixed. At the same time, an elastic sealing member 14 is adhered as a sealing member fixed from the inside of the polygon housing portion 3 to the periphery of the opening 7 and slidably contacting the outer peripheral surface of the lens holder 13 in close contact.

With such a configuration of the opening, the cylindrical lens 12 can be moved together with the lens holder 13 along the optical axis direction of the laser light L while maintaining the airtightness inside the polygon housing 3 by the elastic sealing member 14. And fine positioning becomes possible. Then, the lens holder 13 holding the cylindrical lens 12 at a predetermined position,
An outer part integrally formed with the partition wall is fixed by a screw 15 to fix the cylindrical lens 12 so as not to move.

[0016]

As described above, the writing optical device of the present invention comprises a deflection scanning means for deflecting a laser beam from a light source by a rotating polygon mirror, an optical path for covering the deflection scanning means and for passing the laser beam. In a writing optical device having a shielding member provided with an opening, the opening through which the reflected light from the deflection scanning means is emitted is closed by an fθ lens, so that the storage section of the deflection scanning means is sealed. It is not necessary to provide a sealing means such as a shielding glass at the opening on the emission side in order to achieve the state, and the number of components used for soundproofing and dustproofing can be reduced.

According to the construction in which the opening for letting the laser light from the light source enter the deflection scanning means is closed by a cylindrical lens, it is necessary to provide a sealing means such as a shielding glass in the opening on the incidence side. Without
The number of parts used for soundproofing and dustproofing can be reduced.

Further, the cylindrical lens is fitted into a lens holder, and the lens holder is slidably fitted into the opening, and the cylindrical lens is moved along the optical axis with the opening closed. According to the configuration in which movement in the direction is freely adjustable, the position of the cylindrical lens can be moved and adjusted while maintaining the hermeticity of the storage section of the deflection scanning means,
A high-quality device can be provided while taking soundproofing and dustproofing measures.

[Brief description of the drawings]

FIG. 1 is a top view showing a configuration of a first embodiment of a writing optical device according to the present invention.

FIG. 2 is a sectional view of the apparatus of FIG. 1 taken along the line AA.

FIG. 3 is a top view showing the configuration of a second embodiment of the writing optical device according to the present invention.

FIG. 4 is a sectional view of the device of FIG. 3 taken along line BB.

FIG. 5 is a cross-sectional view showing a configuration in which the position of a cylindrical lens can be adjusted in the writing optical device of Example 2.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Deflection scanning means (polygon scanner) 4, 5, 6 Shielding member 7 Opening for laser light 8 Opening for reflected light 10 fθ lens 11 Light source (LD unit) 12 Cylindrical lens 13 Lens holder 14 Sealing member (Elastic sealing member) L Laser light

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Manabu Manabu 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Company (72) Inventor Yoshiharu Manabe 1-3-6 Nakamagome, Ota-ku, Tokyo Stock F term in Ricoh Company (reference) 2H045 AA34 DA02 DA41

Claims (4)

[Claims] 1. A writing optical system comprising: a deflection scanning unit for deflecting a laser beam from a light source by a rotating polygon mirror; and a shielding member for covering the deflection scanning unit and having an opening as an optical path of the laser beam. A writing optical device, wherein an opening through which reflected light from the deflection scanning means is emitted is closed by an fθ lens. 2. The writing optical device according to claim 1, wherein an opening for allowing the laser light from the light source to enter the deflection scanning means is closed by a cylindrical lens. 3. The cylindrical lens is fitted in a lens holder, and the lens holder is slidably fitted in the opening, and the cylindrical lens is moved along the optical axis with the opening closed. 3. The writing optical device according to claim 2, wherein the writing optical device is movable in a direction. 4. The writing optical device according to claim 3, wherein a seal member is provided between the lens holder and the periphery of the opening.