JPH03293312A - optical scanning device - Google Patents

Abstract

PURPOSE:To eliminate the need of positioning an optical waveguide array and a condensing means to match with each other by providing the condensing means consisting of a photosetting resin having a refractive index distribution which follows a molecular weight distribution on the emitting end of the optical waveguide array. CONSTITUTION:On the downstream side in the propagation direction of a light beam of a light source 11, a collimating lens 12 for converting the light beam be parallel light beams is provided, and also, on its downstream side, a condensing lens 13 for condensing the light beam from the lens 12 is provided. A polygon mirror 14 can be rotated at a high speed by a motor, and by the rotation of this mirror 14, the condensed light beam is led successively to an incident end of an optical waveguide array 15. The incident end 15a of the array 15 is formed in such a circular are shape as surrounds the polygon mirror 14, an emitting end 15b is formed in a linear shape being parallel to the center shaft of a photosensitive drum 20, and the emitting end 15b is provided with a condensing lens 16 which consists of a single composition and made of a photosetting resin hardened with a refractive index distribution, and by a light beam emitted by the emitting end thereby, the photosensitive drum 20 is exposed to one-to-one in accordance with image information.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical scanning device using electrophotographic technology such as a laser printer, and more particularly to an optical scanning device using an optical waveguide array.

[Prior Art] As a prior art, an optical scanning device has been proposed that uses an optical waveguide array to scan a photosensitive drum with a light beam.

This optical waveguide array has a large number of optical waveguides arranged in an arc shape at one end to serve as an input end for a light beam, and the other end arranged in a straight line to serve as an output end for a light beam. This optical waveguide is composed of two types of materials that have different refractive indexes for the light beam from the light source.The material with a higher refractive index forms the core, which forms the center of the optical waveguide, and the material with a lower refractive index, which forms the cladding, forms the center of the optical waveguide. It was formed to surround the surrounding area.

At the output end, a light beam is emitted with an aperture angle determined by the difference in refractive index between the core and the cladding.The light beam at the output end is directed onto the photosensitive drum by a refractive index gradient lens array such as a SELFOC lens array as a focusing means. was irradiated.

[Problems to be Solved by the Invention] However, in an optical scanning device using such an optical waveguide array, since a gradient index lens array, which is a separate member from the optical waveguide array, is used as a condensing means at the output end,
There was a problem in that it was difficult to align the output end of the optical waveguide array and the gradient index lens array. Another problem is that such a gradient index lens array is expensive.

If the output end of the optical waveguide array is placed close to the photosensitive drum without using such a gradient index lens array, the output end will be contaminated by toner on the photosensitive drum, resulting in a decrease in image quality. This caused the

The present invention has been made to solve the above-mentioned problems, and by providing a light focusing means made of a photocurable resin that hardens according to the refractive index distribution at the output end of the optical waveguide array, it is possible to combine the optical waveguide array and the light focusing means. It is an object of the present invention to provide an inexpensive optical scanning device that does not require alignment with optical means.

[Means for Solving the Problems] An optical scanning device of the present invention includes a light source that emits a light beam based on image information, and a large number of optical waveguides that propagate the light beam from the light source from its input end to its output end. an optical waveguide array formed by the optical waveguide array, and an optical deflector that deflects the light beams from the light source so as to make them sequentially enter the input end of the optical waveguide array; The structure includes a light condensing means made of a photocurable resin having a rate distribution.

[Function] In the optical scanning device of the present invention having the above configuration, the light beam emitted from the light source based on image information is sequentially incident on the input end of the optical waveguide array by the optical deflector, and then the light beam is inputted to the output end of the optical waveguide array. However, since a condensing means made of a photocurable resin that hardens according to the refractive index distribution is provided at the output end of the optical waveguide array, the spread of the emitted light beam is suppressed and the light beam is reliably irradiated onto the photosensitive drum. Ru.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

As shown in FIG. 1, the optical scanning device 1o includes a light source 11 that emits a light beam based on image information, and an optical waveguide array formed of a large number of optical waveguides for propagating the light beam from the light source 11 to a photosensitive drum 20. 15, and a polygon mirror 14 for deflecting the light beam from the light source 11 to the input end of the optical waveguide array.

The light source 11 generates a light beam by blinking in response to an electric signal based on image information, and is specifically a laser diode (LD) or a light emitting diode (LED).
Semiconductor light sources such as are used.

A collimating lens 12 is provided on the downstream side in the propagation direction of the light beam of the light source 11 to convert the light beam from the light source 1°1 into a parallel light beam. This collimating lens 12
A condensing lens 13 for condensing the light beam from the collimating lens 12 is provided further downstream.

The polygon mirror 14 is arranged to be rotatable at high speed by a motor (not shown), and the light beams focused by the condenser lens 13 are sequentially guided to the input end of the optical waveguide array 15 by the rotation of the polygon mirror 14. ing.

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 2o. The input end 15a of this optical waveguide array 15 is formed in an arc shape surrounding the polygon mirror 14, and the output end 15b is formed in the shape of an arc surrounding the polygon mirror 14.
It is formed in a straight line parallel to the central axis of. At this output end 15b, there is a condenser lens 30 made of a photocurable resin having a single composition and curing with a refractive index distribution.
As a result, the photosensitive drum 2° is exposed one-to-one in accordance with the image information by the light beam emitted from the output end 15b.

Next, a method of manufacturing the condenser lens 30 will be explained.

The condensing lens 3o as a condensing means is manufactured by the following steps.

(A) The output end 15b of the optical waveguide array 15 is immersed in an uncured photocurable resin material. What is photocurable resin?
For example, an initiator is mixed with an acrylic acid ester polymer (typically, the refractive index at the time of curing is about 1.54), which is an ultraviolet light-curable resin. However, the refractive index when uncured is about 1% lower than when cured.

(B) Light from an ultraviolet light source for curing the material is made uniformly incident from the incident end 15a of the optical waveguide array 15.

(C) Due to the difference in refractive index between the core 21 and the cladding 22, the light that has propagated within the core 21 is emitted at the output end 15b, or the optical power density distribution of this output light beam roughly follows the central axis of each core 21. It is the sum of Gaussian distributions with vertices. Therefore, the degree to which the photocurable resin is cured follows this optical power density distribution, so depending on the degree of curing, the molecular weight distribution, that is, the refractive index distribution, of the uncured part and the cured part changes as shown in Figure 3 (
This occurs as shown in b), and the hardened portion 19 becomes as shown in FIG. 3(a).

For example, using the above material, the optical power of ultraviolet light at one output end 15b can be increased to 30 nm at a wavelength of 360 nm.
If it is 0μW, this ultraviolet light curable resin is about 100m5e
c, it was cured into the chevron shape shown in FIG. 3(a).

(D) After curing, take out the output end 15b of the optical waveguide array 15 from the photocurable resin, and remove it several hundred μm from the output end 15b.
At this point, it is cut parallel to the output end 15b and the end surface is mirror polished. Then, a gradient index condenser lens 16 as shown in FIG. 2 is obtained.

Through the steps described above, the condenser lens 16 is formed at the output end 15b of the optical waveguide array 15.

Next, the operation of such an optical scanning 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, by the rotation of the polygon mirror 14, the light beam from the light source 11 is guided to the input end 15a of the optical waveguide array 15, and is sequentially incident on each optical waveguide constituting the optical waveguide array 15.

The light beam incident on the optical waveguide array 15 is propagated within the core 21 by being totally reflected at the interface between the core 21 and cladding 22 of the optical waveguide due to the relationship in refractive index between them. This light beam is sequentially emitted from each optical waveguide at the output end 15b of the optical waveguide array 15, but at this time, the widening of the emitted light beam is suppressed by the condenser lens 16 having the refractive index distribution as described above. , the light beam is reliably irradiated onto the photosensitive drum 20.

By the above-described operation, the light beam from the light source 11 that blinks depending on the image information 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 2o
is rotated by a drive source (not shown) and optical scanning is performed by repeating optical line scanning.

Further, the condenser lens 16 has the function of suppressing the spread of the emitted light beam due to its refractive index distribution and ensuring that the light beam is irradiated onto the photosensitive drum 20. Since the condensing lenses 16 having the above-mentioned configuration are made by aligning with the corresponding cores 21, there is no need to align the output end 15b and the condensing lens 30 as if they were separate members. do not have. Furthermore, since only a small amount of photocurable resin is used, it can be constructed at a very low cost.

[Effects of the Invention] As described in detail above, the optical scanning device of the present invention is provided with a light condensing means made of a photocurable resin having a refractive index distribution according to the molecular weight distribution at the output end of the optical waveguide array. The light beam emitted from the end is reliably irradiated onto the photosensitive drum. Further, the manufacturing method eliminates the need for alignment between the optical waveguide array and the light condensing means, and has the advantage that it can be constructed at low cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view schematically showing an optical scanning device according to an embodiment of the present invention, FIG. 2 is a plan view of the vicinity of the output end of the optical waveguide array after cutting, and FIG. 3(a) is after curing. FIG. 3(b) is a plan view of the vicinity of the output end of the optical waveguide array, and is a diagram showing the refractive index distribution. In the figure, 11 is a light source, 14 is an optical deflector, 15 is an optical waveguide array, 15b is an output end, and 16 is a condensing means.

Claims (1)

[Claims] 1. A light source that emits a light beam based on image information, 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 beam from the light source. In the optical scanning device, the light beam deflector deflects the light so as to sequentially enter the plurality of optical waveguides. What is claimed is: 1. An optical scanning device characterized by being provided with a light condensing means.