JPH03216615A - optical scanning device - 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 Industrial Application] The present invention relates to an optical scanning device used in optical printers and the like.

[Conventional technology]

In recent years, optical printers using optical scanning devices have been used as computer output devices instead of line printers that have been conventionally used.

Hereinafter, such an optical scanning device will be explained with reference to FIG. 5.

FIG. 5 shows a conventional optical scanning device 50. In this optical scanning device 50, a light beam emitted from a light source 51 is made into a parallel beam by a collimating lens 52, and then passes through a condensing lens 53 and rotates at a constant speed. polygon mirror 54
is deflected at a constant angular velocity by This deflected light beam passes through the fθ lens 55 and reaches the plane reflection plate 56. Then, the light is reflected by the plane reflection plate 56 and scanned on the rotating photosensitive drum 40 along a straight line parallel to its rotation axis.

However, in such a conventional optical scanning device 50, the light beam is deflected by the polygon mirror 54 at a constant angular velocity, whereas it is necessary to scan the photosensitive drum 57 at a constant velocity. For this reason, an expensive optical lens system such as the fθ lens 55 shown in FIG. 5 is required to convert the uniform angular velocity movement of the light beam into uniform velocity scanning.

As a method to compensate for such drawbacks, an optical scanning device 60 has been proposed in which an optical waveguide array 61 is used in place of the fθ lens 55 to scan the photosensitive drum 57 with a light beam. This optical waveguide array 61 has a large number of optical waveguides arranged in an arc shape at one end to serve as a light beam entrance end 61a, and the other end arranged in a straight line to serve as a light beam output end 6lb. This optical waveguide has two different refractive indexes for the light beam emitted from the light source 51.
A material with a high refractive index forms the core, which forms the center of the optical waveguide, and a material with a low refractive index, which forms the cladding, surrounds the core.

[Problem to be solved by the invention]

However, in such an optical scanning device 60,
When the light beam deflected by the polygon mirror 54 is incident on each optical waveguide constituting the optical waveguide array 61, it is necessary to There has been a problem in that the light beam may not be correctly incident on the entrance of the optical waveguide due to poor horizontal positioning accuracy.

In order to solve this problem, a separately manufactured light beam guiding means is provided at the entrance of the optical waveguide array, and this light beam guiding means allows the light beam to correctly enter the entrance of the optical waveguide. There is something I did. However, such a light beam guiding means is equipped with a pair of reflecting mirrors that face each other at a predetermined angle, and requires high processing precision, making it difficult to manufacture.

Further, there was a problem in that it was difficult to position the optical beam guiding means with respect to the optical waveguide array.

The present invention has been made to solve the above-mentioned problems, and includes an optical waveguide array that is easy to manufacture and that can reliably make the light beam emitted from the light source enter the entrance of the optical waveguide. The purpose of the present invention is to provide an optical scanning device.

[Means to solve the problem]

To achieve this object, the present invention provides a light source that emits a light beam based on an image signal, an optical waveguide array formed by arranging a large number of optical waveguides that propagate the light beam from the light source, and a light source that emits a light beam from the light source. and a light beam distributing means for sequentially inputting the light beam into the optical waveguide, the light beam guiding means guiding the light beam from the light beam distributing means to the entrance of the optical waveguide. The optical beam guiding means is formed integrally with the optical waveguide array so as to form opposing surfaces facing each other at a predetermined angle, and the opposing surfaces are mirror surfaces.

[Effect]

In the optical scanning device of the present invention having the above configuration, the light beam emitted from the light source based on the image signal is deflected by the light beam distribution means and sequentially guided to the entrance of each optical waveguide of the optical waveguide array.

At this time, the light beam that has entered from the entrance of the optical waveguide is guided to the entrance of the optical waveguide array by a light beam guiding means formed integrally with the leading waveguide array and having a mirror surface. Then, this light beam is propagated within the guide wavepath and is sequentially emitted from the output end of the guide waveway array, thereby performing scanning of the light beam.

Furthermore, since this optical beam guiding means is integrally formed with the optical waveguide array, manufacturing is easy.

〔Example〕

Hereinafter, embodiments embodying the present invention will be described with reference to the drawings.

FIG. 1 shows an optical recording device 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 light beam from the light source 11 that is transferred to a photosensitive drum 2.
The optical waveguide array 15 includes an optical waveguide array 15 formed by multiple rows of optical waveguides for propagation to zero, and a polygon mirror 14 for distributing the light beam from the light source 11 to the entrance of each optical waveguide.

The light source 11 generates a light beam by blinking in response to an electric signal based on image information, and specifically, a semiconductor light source such as a laser diode (LD) or 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 beam. A condenser lens 13 is provided further downstream of the collimator lens 12 to condense the light emitted from the collimator lens 12 onto a polygon mirror 14 .

The polygon mirror 14 is arranged to be rotatable at high speed by a motor (not shown). And this polygon mirror
14, the light beam focused by the condenser lens 13 is sequentially guided to the entrance of each optical waveguide constituting the optical waveguide array 15.

The optical waveguide array 15 is formed such that a large number of optical waveguides for propagating the light beam emitted from the light source 11 to the photosensitive drum 20 are arranged in a row.

The input end 15a of the optical waveguide array 15 is formed in an arc shape surrounding the polygon mirror 14, and the output end 15b is formed in a straight line parallel to the central axis of the photosensitive drum 20.

FIG. 2 is a cross-sectional view of the optical waveguide array 15.

In FIG. 2, the optical waveguide array 15 is formed by combining a cladding material 16 in which grooves 16a are formed at a predetermined pitch and a flat cladding material 17. A core material is filled in the cavity formed by both cladding materials 16 and 17 to form a core 18. The cladding material may be, for example, polymethyl methacrylic resin (PMMA) having a refractive index of about 1.4, and the core material may have a refractive index of 1.59.
Polycarbonate resin etc. are used.

3 is a perspective view showing the vicinity of the input end 15a of the optical waveguide array 15, and FIG. 4 is a perspective view showing the vicinity of the input end 15a of the optical waveguide array 15.
It is a sectional view of the vicinity of 5a in the optical pongee direction. In FIGS. 3 and 4, guide portions 16a and 17a whose cross-sectional area gradually decreases are formed in the cladding material 16, 17 of the optical waveguide array.

This guiding portion 16a. The inner surfaces of 17a face each other at a predetermined spread angle θ. Mirror surfaces 16b and 17 on which metal such as aluminum is vapor-deposited are formed on the inner surfaces.
b is formed. Therefore, this mirror surface 16b,1
Reference numeral 7b constitutes a light beam guiding means that faces each other at a predetermined spread angle θ.

In this way, in the present invention, since the optical beam guiding means is formed integrally with the optical waveguide array, it is easy to manufacture the optical beam guiding means, and it is possible to install the optical beam guiding means on the optical waveguide array. positioning is not required.

In such an optical waveguide array 15, a light beam irradiated from the left direction in FIG.
guided by. By configuring the optical waveguide array 15 in this way, the light beam is directed to the core 1 of the optical waveguide array 15.
Even if the optical waveguide enters at a position slightly deviating from the optical waveguide array 15, it is possible to reliably guide the optical waveguide to the core 18 of the optical waveguide array 15.

Here, for example, the diameter of the parallel beam from the collimating lens 12 is 2 mm, and the diameter of the parallel beam from the condensing lens 13 is set to 2 mm.
The optical path length to the incident end 15a is 50 mm, and the convergence angle of the light beam by the condenser lens 13 is approximately 1.5°. It is assumed that the light beam exiting the condenser lens 13 is a parallel beam, and that the light beam is reflected twice between the mirror surfaces 16b and 17b of the light beam guiding means. in this case,
The first reflection changes the optical path by θ, and the second reflection changes it by 3θ, so the final optical path of the light beam changes to 2θ.
It's going to change. This is the core 18 of the optical waveguide array.
It is considered that all the light beams are incident on the core 18 if the critical angle θa is not exceeded. Therefore, the possible range of the spread angle θ is 2θ≦θa. Within this range, the maximum width W at the tip of the optical waveguide array 15 is determined under the condition of θ = θ a /2.

For example, the width d of the core 18 is 100 μm, the critical angle θa is 3
If a 0° optical waveguide is used, the divergence angle θ is 15 from the above equation.
°. In this case, the length l of the light beam guiding means of the optical waveguide array 15 is 1.4 mm, and the maximum aperture width W is 470 μm.
m optical waveguide arrays can be used. Therefore, the permissible positioning range of the light beam from the center position of the optical waveguide array 15 is ±50 μm for the conventional optical waveguide array.
On the other hand, by forming the light beam guiding means, it becomes significantly larger to ±235 μm.

Next, the operation of such an optical recording device 10 will be explained.

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

Then, as the polygon mirror 14 rotates, the light beam from the light source 11 is sequentially incident on each optical waveguide constituting the optical waveguide array 15. Here, as described above, the light beam guiding means is formed in the leading waveguide array, and includes mirror surfaces facing each other at a predetermined spread angle θ. Therefore, even if the light beam enters the optical waveguide with some deviation from the center due to the tilting of the surface of the polygon mirror 14 or poor positioning accuracy of the optical waveguide array 15, the core 18 of the optical waveguide array guided by.

The light beam incident on the optical waveguide array 15 propagates within the core 18 by being totally reflected at the interface between the core 18 and the claddings 16 and 17 due to the relationship between the refractive index of the core 18 and the claddings 16 and 17 of the optical waveguide array 15. be done.

This light beam then passes through the core 18 and the cladding 16.17.
The light is sequentially emitted from the output end 15b of the optical waveguide array 15 at an aperture angle determined by the refractive index.

Through the above-described operation, the light beam 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, each time one line of light scanning is completed, the photosensitive drum 2
0 is intermittently rotated by a drive source (not shown) and image recording 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, in the embodiment described above, cladding 16.17
guiding portion 16a. 17a is formed by decreasing its cross-sectional area at a constant rate of change, but this rate of change may be gradually varied. Furthermore, it is also possible to make the spot diameter of the light beam at the entrance end of the optical waveguide array larger than the width of the entrance of the optical waveguide and allow the light beam to enter the optical waveguide array.

〔Effect of the invention〕

As is clear from the detailed description above, according to the present invention, since the optical beam guiding means is integrally formed in the optical waveguide array, even if the optical beam enters from the center of the optical waveguide, the optical beam It is possible to reliably guide the optical waveguide to the propagation part of the core of the predetermined optical waveguide, and it is also easy to manufacture.

[Brief explanation of drawings]

FIG. 1 is a perspective view schematically showing an optical scanning device according to the present invention;
Fig. 2 is a cross-sectional view of the optical waveguide array, Fig. 3 is a perspective view showing the vicinity of the input end of the optical waveguide array, Fig. 4 is a sectional view in the optical axis direction near the input end of the optical waveguide array, and Fig. 5 and the sixth
Each figure is a perspective view schematically showing a conventional optical scanning device. DESCRIPTION OF SYMBOLS 10... Optical scanning device, 11... Light source, 14... Polygon mirror 15... Optical waveguide array, 16b, 17b... Mirror surface.

Claims (1)

[Claims] a light source that emits a light beam based on an image signal; an optical waveguide array formed by arranging a number of optical waveguides through which the light beam from the light source propagates; and a light beam from the light source that sequentially enters the optical waveguide. The optical scanning device includes a light beam distribution means for guiding the light beam from the light beam distribution means to an entrance of the optical waveguide, and the light beam guide means are arranged at a predetermined angle with respect to each other. An optical scanning device characterized in that it is integrally molded with the optical waveguide array so as to form opposing surfaces facing each other, and the opposing surface is a mirror surface.