JPH04152317A - Optical scanner - Google Patents

Abstract

PURPOSE:To enter a part of an optical beam which is not made incident on an input end and to relax an allowable deviation value in the vertical direction of the optical beam by disposing a plane mirror in the vicinity of the input end of an optical waveguide array. CONSTITUTION:The optical beam B based on a picture signal from a light source 11, is reflected by a rotary inclined mirror 14, and sequentially made incident on the optical waveguide array 15. The beam B made incident on the array 15 is transmitted inside a waveguide, and outgoes from an emitting end 15b, and the surface of a photosensitive drum 20 is irradiated. At this time, the plane mirror 18 is disposed adjacent to the whole limit of the incident end 15a of the array 15. Thus, a part of the beam which is not made incident on the incident end 15a caused by the plane tilt of the mirror 14 and an axis deviation is reflected by the mirror 18 and can be made incident. Therefore, the allowable deviation value in the vertical direction of the optical beam can be relaxed with a simple constitution.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an optical scanning device used in an optical printer or the like.

[Conventional technology]

In recent years, optical printers have been used to replace the line printers traditionally used as computer output devices.
This optical printer uses an optical scanning device.

Hereinafter, such an optical scanning device will be explained with reference to FIG. 4.

FIG. 4 shows a conventional optical scanning device 30. In this optical scanning device 30, a light beam from a light source 31 is made into a parallel beam by a collimating lens 32, and then
3 and is deflected at a constant angular velocity by a tilting mirror 34 which rotates at a constant velocity.

The trajectory of this deflected light beam lies on one plane, and is incident on the incident end 35a of the flat optical waveguide array 35 on the same plane. The light beam propagates through each leading wavepath and is emitted from its output end 35b. The light is then irradiated onto the rotating photosensitive tram 40 along a straight line parallel to its rotation axis, and one line is scanned by one rotation of the tilting mirror 34.

This optical waveguide array 35 has a large number of optical waveguides arranged in an arc shape at one end to serve as a light beam input end 35a, and the other end arranged in a straight line to serve as a light beam output end 35b. The optical waveguide 35 is made of two types of transparent resins having different refractive indexes for the light beam from the light source, and the material with a high refractive index forms the center of the optical waveguide as a core. A small material is formed as a cladding surrounding the core.

[Problem to be solved by the invention]

However, in conventional optical scanning devices, the deflected light beam does not enter the optical waveguide correctly due to surface tilt or axis misalignment of the rotating reflector, as well as installation errors and deformation of each member over time. There was a problem that the image would be rubbed off.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide an optical scanning device that can reduce the permissible positional deviation amount in the vertical direction with a simple configuration.

[Means for Solving the Problem] In order to achieve this object, an optical scanning device of the present invention includes a light source that emits a light beam based on an image signal, and a large number of optical waveguides that propagate the light beam from the light source. An optical scanning device comprising: a flat plate optical waveguide array formed by arranging a plurality of optical waveguides; and a rotating reflecting mirror for reflecting a light beam from the light source on a mirror surface and sequentially inputting the light beam to the plurality of optical waveguides. A plane mirror is disposed near the input end of the array, and at least a portion of the light beams reflected from the rotating reflecting mirror but not incident on the input end is made to enter the input end. I did it like that.

[Effect]

In the present invention having the above configuration, a light beam emitted from a light source based on image information is deflected at a constant angular velocity by a rotating reflecting mirror, and sequentially enters an optical waveguide array.

At this time, since a plane mirror used for guiding the light beam is provided near the input end of the optical waveguide, the light beam is either directly input to the input end of the optical waveguide, or even if it is not directly input, it is reflected once by the plane mirror. It is incident. Therefore, the allowable width of the deviation of the light beam is approximately twice the deviation with respect to the incident end.

〔Example〕

An embodiment embodying the present invention will be described below with reference to the drawings.

FIG. 1 shows an optical scanning device 10 according to the present invention.

In FIG. 1, an optical scanning device 10 includes a light source 11 that generates a light beam based on an image signal, and a flat light guide in which a large number of optical waveguides are arranged in rows for propagating the light beam from the light source 11 to a photosensitive drum 20. A waveguide array 15, an inclined mirror 14 for deflecting the light beam from the light source 11 at a constant angular velocity and sequentially inputting it into the leading waveguide array 15, and a plane mirror adjacent to the entire lower surface range of the input end 15a of the optical waveguide array 15. 18
It is equipped with

The light source 11 blinks and generates a light beam based on an electric signal based on image information, and specifically, a laser diode (L
D) Alternatively, a semiconductor light source such as a light emitting diode (LED) is used.

A collimating lens 12 is provided downstream in the propagation direction of the light beam from the light source 11 to convert the light beam from the light source 11 into a parallel light beam. This collimating lens 12
Further downstream, a condenser lens 13 is provided for condensing the light emitted from the collimator lens 12 onto the input end 15a of the optical waveguide array 15. Tilt mirror 14
is arranged to be rotatable at high speed by a rotating means such as a motor (not shown). Each member is accurately aligned and arranged so that the light beam condensed by the condenser lens 13 by the rotation of the tilted mirror 14 is sequentially guided to each optical waveguide constituting the input end 15a of the optical waveguide array 15. It is set up.

The optical waveguide array 15 is formed by arranging a large number of optical waveguides for propagating the light beam emitted from the light source 11 to the photosensitive drum 20. The input end 15a of the optical waveguide array 15 is formed in an arc shape centered on the rotation axis of the tilted mirror 4, and the output end 15b is formed in a straight line parallel to the central axis of the photosensitive drum 20. Further, each end face of the entrance end 15a and the exit end 15b is mirror polished and arranged in parallel to the vertical direction.

FIG. 2(A) shows a sectional view of a main part of the optical scanning device 10, and FIG. 2(B) shows a specific example of the angular relationship between the light beam and the tilted mirror.

As shown in FIGS. 2(A) and 2(B), the light beam B emitted vertically downward by the light source 11 passes through the collimating lens 12 and the condensing lens 13, and then passes through the inclined mirror 14.
The incident end 15 of the optical waveguide array 15 is deflected by 80 degrees at the mirror surface 14a of
Head to a.

That is, the angle of the mirror surface 14a of the main diagonal mirror 14 is 40 degrees with respect to the vertical direction, and in order to make the light beam reflected by the mirror surface 14a enter the input end 15a, this mirror surface 14a must be connected to the optical waveguide array 15. It is necessary to arrange the optical waveguide at a position that does not intersect the plane formed by extending the optical axis of each optical waveguide at the input end 15a of the optical waveguide. That is, the mirror surface 14a needs to be disposed above the extension plane. Therefore, by rotating the main oblique mirror 14, the trajectory of the light beam is changed to the mirror surface 14.
It has a conical shape with a as its apex.

The optical waveguide array 15 is composed of two types of translucent materials having different refractive indexes for the light beam from the light source 11. The material with a high refractive index forms the center of the optical waveguide as a core 16a, and the material with a high refractive index forms the center of the optical waveguide as a core 16a. A small material is formed as a cladding 16b to surround the core 16a. Therefore, as shown in FIG. 3(A), cores 16a and claddings 16b are alternately arranged in parallel at regular intervals at the entrance end. Further, the light beam is focused so that the beam spot 17 is larger than the cross-sectional area of the core 16a, and is incident on the optical waveguide array 15. In this way, the influence of the shift in the vertical position of the light beam at the incident end 1'5a is alleviated.

Now, the cross-sectional shape of the core 16a is circular, with a diameter of 50 microns, as shown in FIG.
6a are arranged in parallel with a horizontal position (pitch) of every 85 microns.

In this case, by setting the beam diameter of the light beam B to 200 microns or more, the deviation in the vertical position of the beam spot 17 is suppressed, and the amount of fluctuation in the transmitted optical power due to the incident position is suppressed within a predetermined range (for example, ±10%). Taking this into account, it was confirmed through experiments that a thickness of up to 80 microns is permissible.

As shown in FIGS. 2(A) and 2(B), the light beam B that is incident on the optical waveguide array 15 at an angle of 80 degrees in the vertical direction as described above is caused by the tilted surface of the tilted mirror 14. Due to axis misalignment, installation errors of each component, and deformation over time,
There was a concern that the light would be shifted in the vertical direction and would not enter the optical waveguide correctly. When using the optical waveguide array 15 of the size described above, the permissible vertical positional deviation is 80
It is micron. However, in the present invention, since the plane mirror 18 is provided adjacent to the entire lower surface area of the input end 15a of the optical waveguide array 15, the effect of the mirror surface makes it appear as if the virtual image 15c of the optical waveguide array 15 exists there. Therefore, the permissible vertical positional deviation is 160 microns, which is twice that without the plane mirror 18. Further, in order to obtain this effect, it is preferable that the thickness of the optical waveguide is 80 microns or less, which is the permissible vertical displacement amount. Thereby, power fluctuations caused by vertical positional deviation can be suppressed to a very small level.

As described above, according to the present invention, it is possible to obtain the effect that the vertical deviation can be reduced by twice as much by using a very simple configuration.

Next, the operation of the optical scanning device 10 will be explained using FIG.

The light source 11 blinks and emits a light beam B based on an image signal, and this light beam B is guided to an inclined mirror 14 via a collimating lens 12 and a condensing lens 13.

The light beam B from the light source 11 is caused by the rotation of the tilted mirror 14.
is sequentially incident on each optical waveguide constituting the optical waveguide array 15. Light beam B incident on the optical waveguide array 15
The light propagates within the guide wave path, is emitted from the output end 15b, and is irradiated onto the surface of the photosensitive drum 20.

Here, as described above, the light beam is oriented at an angle of 80 degrees in the vertical direction (see FIG. 2(B)) at the incident end 15a of the optical waveguide array 15.
Since the plane mirror 18 is provided adjacent to the entire range of the incident end 15a, the permissible positional deviation in the vertical direction can be reduced to 2.
It has the effect of being able to relieve stress twice as much.

By the above-described operation, the light beam B from the light source 11 that blinks in response to the image signal is scanned at a constant speed in the direction of the central axis of the photosensitive drum 20, and an image is recorded. Then, the photosensitive drum 20 is rotated at a constant speed by a drive source (not shown), and optical scanning is performed by repeating optical line scanning.

Note that the present invention is not limited to the embodiments described above, and modifications can be made as appropriate.

For example, the plane mirror 18 may be a part of a main body member (not shown) that integrates each member constituting the optical scanning device according to the present invention.

〔Effect of the invention〕

As is clear from the detailed description above, according to the present invention, the light beam reflected by the rotating reflecting mirror is directly incident on the incident surface or reflected by a plane mirror disposed adjacent to the flat optical waveguide array. Since the light beam can be incident on the incident surface, it is possible to reduce the permissible deviation amount of the light beam in the vertical direction with a simple configuration.

[BRIEF DESCRIPTION OF THE DRAWINGS] FIGS. 1 to 4 show embodiments embodying the present invention. FIG. 1 is a schematic perspective view of an optical scanning device according to the present invention, and FIG. A) and (B) are cross-sectional views and angular explanatory views of the optical scanning device according to the present invention, and FIGS. 3 (A) and (B) are side views and specific dimensions of the incident end of the guiding waveguide array according to the present invention. A side view showing an example, and FIG. 4 is a schematic perspective view of a conventional optical scanning device. 10... Optical scanning device 11... Light source 4... Rotating reflecting mirror 4a... Mirror surface 5... Optical waveguide array 5a... Incident end 8... Plane mirror

Claims (1)

[Claims] A light source that emits a light beam based on an image signal, a flat optical waveguide array formed by arranging a large number of optical waveguides that propagate the light beam from the light source, and In an optical scanning device equipped with a rotating reflector for reflecting a light beam on a mirror surface and making it sequentially enter the plurality of optical waveguides, a plane mirror is disposed near an input end of the optical waveguide array, and a plane mirror is provided near the input end of the optical waveguide array, An optical scanning device characterized in that at least a part of the reflected light beams that are not incident on the input end are made incident on the input end.