JPS63137205A - Laser optical system - Google Patents

Abstract

PURPOSE:To evade the dew condensation on optical components and to perform fine image recording by providing a means which closes an optical housing hermetically between a cover member and a casing which form the optical housing wherein a laser light source, an optical deflector, and a lens are arranged. CONSTITUTION:A laser optical system 10 includes the optical housing 12 nearly in the shape of a rectangular prism where a swelling part is formed. The housing 12 consists of a casing 14, a casing 16 which swells outward from one flank 14 of the casing 14, and the cover member 18 which seals the opening parts of the casings 14 and 16 integrally. A slit opening part 20 is provided to the bottom part of the casing 14, and the opening part 20 is sealed with light- transmissive glass 22. The semiconductor laser 24, a collimator lens 26, a rotary polygon mirror 28, an ftheta lens 30, and a mirror 32 are arranged in the casings 14 and 16. The casings 14 and 16 and member 18 are sealed internally by a sealing mechanism 38 which includes a female type seal member 40 and a male type seal member 42. Thus, dew condensation on optical components is evaded and a fine image can be recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a laser optical system, and more particularly to a laser light source and an optical member provided on the optical path of a laser beam emitted from the laser light source, in particular a laser constituting a rotating polygon mirror. The present invention relates to a laser optical system configured to prevent dew condensation from forming on a beam reflecting surface, thereby preventing density unevenness or the like from occurring in the image itself when recording an image on a film or the like using a laser beam.

2. Description of the Related Art Conventionally, optical beam scanning devices that scan a laser beam by deflecting it using an optical deflector have been widely employed in, for example, various image scanning recording devices, image scanning reading devices, and the like.

In such a light beam scanning device, a light source such as a laser oscillator or a semiconductor laser, an optical deflector such as a galvanometer mirror or a rotating polygon mirror, and optical components such as lenses and mirrors are incorporated into the housing that houses the optical system. is common.

By the way, if dew condensation occurs on this type of optical component during scanning operation or non-operation of the laser beam, discoloration will occur on the optical component corresponding to the shape of the condensation. Therefore, when the laser beam is transmitted or reflected through this burnt area and scanning is attempted, the area interferes with the normal transmission or reflection of the laser beam, resulting in a significant drop in the performance of the optical system. , causing problems such as the convergent beam shape being disturbed and image unevenness occurring.

For example, in an optical system such as a laser printer that uses a rotating polygon mirror to deflect and scan a laser beam, the variation in reflectance between the multiple mirror bodies that make up the rotating polygon mirror is reduced to 0.2.
It is necessary to keep it below %. In this case, as a result of dew condensation and discoloration occurring on the mirror bodies that make up the rotating polygon mirror, if the reflectance of the laser beam by the multiple mirror bodies varies by 0.2% or more, the displayed image will have a high density. This is because unevenness occurs. In particular, when transporting a light beam scanning device or bringing it indoors for storage and unpacking the optical system, there is a possibility that condensation may form due to the difference in atmospheric temperature inside and outside the optical housing. becomes significantly higher. Furthermore, once dew condensation occurs on an optical component, striped marks remain on the surface of the component even after the dew dries, causing the same deterioration in optical performance as described above.

The present invention has been made in order to overcome the above-mentioned disadvantages, and by making the casing in which various optical components are placed into a substantially shielding structure, the optical system can be transported, stored, installed, and Optical components arranged on the optical path of the laser beam inside the optical system during operation and non-operation after installation,
In particular, it is an object of the present invention to provide a laser optical system that avoids dew condensation on an optical deflector, thereby making it possible to record precise images.

To achieve the above object, the present invention comprises a laser light source;
an optical deflector, a lens and the laser light source, an optical deflector,
The laser optical system includes an optical casing in which a lens is housed, and is characterized in that a means for sealing the casing is provided between a cover member forming the optical casing and the casing.

Next, preferred embodiments of the laser optical system according to the present invention will be described in detail with reference to the accompanying drawings.

In FIG. 1, reference numeral 10 indicates a laser optical system,
This laser optical system 10 includes a substantially rectangular parallelepiped optical housing 12 in which a bulge is formed. In fact, the optical housing 12 includes a casing 14, a casing 16 that bulges out from one side of the casing 14, and a cover member 18 that integrally closes the opening of the casing 14.16.

A slit-shaped opening 20 is provided at the bottom of the casing 14 through which a laser beam to be scanned is guided to the outside. As can be easily understood from FIG. 1, the casing 14 and the casing 16 are in communication with each other, and in this case, the opening 20 is provided to prevent atmospheric air from flowing between the inside and the outside of the casing 14.16. Therefore, a glass 22 with excellent light transmittance is attached.

A semiconductor laser 24 is disposed inside the casing 16 . A laser beam exit of the semiconductor laser 24 faces a collimator lens 26 attached to the casing 14. A rotary polygon mirror 28 is rotatably supported on the optical axis of the collimator lens 26.

On the other hand, the semiconductor laser 2 is centered around the rotating polygon mirror 28.
An fθ lens 30 is disposed in a direction perpendicular to 4. Further, a mirror 32 is provided substantially parallel to the fθ lens 30 and inclined at 45 degrees with respect to the vertical direction, for example. The mirror 32 faces a glass 22 mounted in the opening 20 of the casing 14.

Although not shown in the above configuration, for example, an optical modulator and a cylindrical lens are disposed between the semiconductor laser 24 and the rotating polygon mirror 28, and fθ
It is preferable to arrange a different cylindrical lens between the lens 30 and the mirror 32, since this makes it possible to correct the tilt of the rotating polygon mirror 28.

Here, the sealing mechanism 38 that joins the casing 14, 16 and the cover member 18 and seals the inside of the optical housing 12 will be described in detail below. The sealing mechanism 38 includes a female seal member 40 and a male seal member 42. in this case,
A female seal member 40 is attached so as to surround the upper end surface of the casing 14,16.

On the other hand, a male seal member 42 is attached to the lower edge of the cover member 18 in correspondence with the seal member 40 . As shown in FIG. 2, the sealing member 40 includes a base 44 that goes around the upper surface of the casing 14.16 and an outer fitting member 46 made of synthetic resin.
a and 46b. External fitting member 4
6a and 46b extend substantially parallel to each other in the circumferential direction of the base 44, and between them there is a substantially circular circumferential groove 52 with an open top.
is formed.

On the other hand, the sealing member 42 includes a base 54 that goes around the edge of the lower surface of the cover member 18 and a fitting protrusion 56 that is formed integrally with the base 54 and is directed downward. The fitting protrusion 56 has a distal end portion 58 having a substantially circular cross section.

In the above configuration, the casing 14 and 16 in which the semiconductor laser 24, the rotating polygon mirror 28, etc. are disposed is closed with the cover member 18. That is, if the cover member I8 is pressed against the casing 14.1G, the fitting protrusion 5
6 fits into the circumferential groove 52, and the housing 12 has a sealed structure.

The laser optical system according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, the general operation of the laser optical system 10 is as follows. That is, the laser beam L derived from the semiconductor laser 24 is converted into a parallel beam by the collimator lens 26 and is incident on the rotating polygon mirror 28 . Next, the laser beam L is deflected by the rotating polygon mirror 28, and is focused by the fθ lens 3o so that the laser beam L passing through the fθ lens 30 scans a plane at a constant speed.

This focused laser beam is reflected by the mirror 32 and guided to the outside through the glass 22. At this time, although not shown, a sheet body such as a film is being conveyed below the opening 2o, and therefore, the laser beam L scans the scanned surface of this sheet body, thereby acquiring image information etc. A record will be made.

In the laser optical system 10 that performs the above-described actions, the dew condensation prevention mechanism according to the present invention provides the following actions to the optical components. In other words, if a laser scanning device containing such a laser optical system is brought in from outdoors and unpacked indoors, condensation may occur if the temperature of the laser optical system is lower than the indoor atmospheric temperature. . In this case, condensation on the outside of the laser optical system does not affect the optical performance, but condensation on the optical parts inside the laser optical system, especially on the rotating polygon mirror 28, significantly degrades the optical performance and This may cause shape disturbances, image unevenness, etc. Furthermore, when setting up the laser optical system, the optical housing 12) or the semiconductor laser 2 disposed inside the optical housing 12)
4. If condensation occurs on the collimator lens 26, rotating polygon mirror 28, fθ lens 30, etc., even if the dew dries, traces of condensation such as discoloration will remain, and the traces of condensation will be removed during the next operation. This causes the same performance degradation as described above.

Therefore, in the present invention, seal members 40, 42 are applied to the joint surfaces of the casing 14, 16 and the cover member 18, so that the optical housing 12 has a sealed structure.

Therefore, air containing moisture will not enter the inside of the optical housing, and condensation will be effectively prevented. Therefore, the optical system including the rotating polygon mirror 28 without condensation can achieve the effect of scanning the desired laser beam and recording or reading the desired image. Furthermore, when performing maintenance inside the optical housing 12, the cover member 18
The effect is that it can be easily attached and detached.

FIG. 3 shows another embodiment of the laser optical system according to the present invention. In this laser optical system, the same reference numerals as in the embodiment described above indicate the same components, and detailed explanation thereof will be omitted.

As can be easily seen in the figures, in this embodiment, in particular, the sealing member 42 extends outwardly from the cover member 18, while the sealing member 40 likewise extends outwardly from the casing 14.16. and has been extended.

In this embodiment, the optical housing 12 has a sealed structure by fitting seal members 40, 42 extending outward from the optical housing 12.

That is, according to this embodiment, when attaching and detaching the cover member 18, for example, the seal members 40 and 42 are attached to the housing 1.
2, so that after the cover member 18 is mounted on the casing 14.16, the base 44 and the base 5
The sealing member 40 and the sealing member 42 can be fitted together by bending the sealing member 4 with a relatively small force as if pinching the sealing member 4 between fingers. Moreover, the lid can be opened easily. With this configuration, it is possible to avoid the risk of dew condensation occurring during transportation, storage, installation, and after installation of the laser scanning device including the optical housing.

As described above, according to the present invention, although the configuration is extremely simple, it is possible to effectively prevent dew condensation from occurring mainly on the rotating polygon mirror that constitutes the laser scanning device. Therefore, the laser beam derived from the semiconductor laser is always scanned by the rotating polygon mirror whose reflection efficiency is within the permissible value, resulting in the effect that images can be effectively recorded or read. In other words, by avoiding dew condensation on the mirror surface of the rotating polygon mirror, it does not adversely affect the convergence or directionality of the laser beam, and it is possible to prevent the optical components from becoming burnt and to avoid the occurrence of image density unevenness, etc. Various effects can be obtained.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments.
Of course, various improvements and changes in design are possible without departing from the gist of the present invention.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective explanatory view of a first embodiment of the laser optical system according to the present invention, FIG. 2 is a partial vertical cross-sectional view of a housing constituting the laser optical system according to the present invention, and FIG. FIG. 3 is a partial vertical cross-sectional view of a second embodiment of the laser optical system according to the present invention. 10... Laser optical system 12... Optical housing 14
．． 16...Casing 18 River power spring member 22...
・Glass 24...Semiconductor laser 26...
・Collimator lens 28...Rotating polygon mirror 30...
fθ lens 32...Mirror 40.42...
Seal members 46a, 46b...outer fitting member 56...
・Mating protrusion

Claims (3)

[Claims] (1) In a laser optical system including a laser light source, an optical deflector, a lens, and an optical housing in which the laser light source, optical deflector, and lens are housed, a cover member and a casing forming the optical housing are combined. A laser optical system characterized in that it is configured to include means for sealing the casing in between. (2) In the optical system according to claim 1, the sealing means includes a cover member and a male and female fitting member disposed on the circumferential edge of the casing. (3) The optical system according to claim 2, wherein the male and female fitting members extend outward from the cover member and the casing.