JPH03171004A - Production of optical device - Google Patents

Abstract

PURPOSE:To prevent the deterioration in image quality by crosstalks by mounting a filter of the light transmittance increasing gradually from the center to the exit port side of respective optical waveguides and exposing the exit port side so as to photopolymerize the same, then removing the residual monomers. CONSTITUTION:A condenser lens 12 is provided on the irradiation side of a light source 11 and the incident port side of the optical waveguide 14 of a scanner 13 is provided on the irradiation side of this condenser lens 12. The filter of the light transmittance increasing gradually from the center is mounted to the exit port side of the respective optical waveguides 14 in this case and the exit port side is so exposed as to photopolymerize the same; thereafter, the residual monomers are removed. Optical devices 18 are then formed on the exit port side of the optical waveguides 14. The exit light rays from the optical waveguides 14 are focused by the optical devices 18. The crosstalking of the exit light rays is obviated and the deterioration in the image quality is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing an optical device, and particularly to a method of manufacturing an optical device on the output end side of an optical waveguide bundle.

[Conventional technology]

In recent years, optical scanning devices have become known, which irradiate and transport optical signals to an optical fiber bundle formed by bundling a plurality of optical fibers, and irradiate the optical signal from this optical fiber bundle onto a photosensitive member for exposure. There is.

FIG. 4 is a perspective view of a conventionally commonly used optical scanning device. Reference numeral 1 in the figure is a light source, which is an LD or an LED.
It is formed by etc. A collimator lens 2 and a condensing lens 3 are provided on the irradiation side of the light source 1. Furthermore, the entrance side of the optical waveguide 5 of the scanner 4 is provided on the irradiation side of the condensing lens 3. Here, as shown in FIG. 5, the optical waveguide 5 has a substantially L-shaped vertical cross section, and is buried so that the output side of the optical waveguide 5 is emitted onto the circumferential side of the rotating body 6. has been done. Also,
Reference numeral 7 in the figure represents a motor, which rotates the rotating body 6 at a constant speed.

Further, a condensing lens 8 is provided on the exit side of the leading waveguide 5, and the optical signal transmitted through the optical waveguide 5 is condensed. Furthermore, an optical fiber bundle 9 is provided on the irradiation side of the condenser lens 8, with its entrance opening shaped like an arc so as to surround the scanner 4 (FIG. 4). Further, the output side of the optical fiber bundle 9 is arranged parallel to the generatrix direction of the photosensitive drum 10.

The operation of the optical scanning device configured in this way will be explained.

An optical signal emitted from a light source 1 passes through a collimator lens 2 and a condensing lens 3 and enters the leading waveguide 5 from the entrance side thereof. At this time, the rotating body 6 in which the optical waveguide 5 is embedded is rotated by the motor 7. In this state, the optical signal emitted from the exit side of the optical waveguide 5 is condensed by the condenser lens 8 so as to be narrowed down to the entrance of the optical fiber bundle 9. As the rotating body 6 rotates, optical signals are sequentially input to each optical fiber. The optical signal incident on this optical fiber bundle 9 is transmitted to the photosensitive drum 10 from the exit side.
is irradiated. As a result, the photosensitive drum 10 can be exposed for one line first. Then, by sequentially repeating this operation, the photosensitive drum 10 can be exposed to an image.

? Incidentally, in the optical scanning device as described above, the aperture angle NA on the exit side of the optical fiber bundle 9 is expressed by the l-order equation from the refractive index nSn2 of the core and cladding of each optical fiber.

NA=Sin(r)■, ...(1)2
．． 2) l/2,. , (2) NA= (n,
2 Then, for example, PMMA (n 1 = 1.4
9) and fluororesin (n2=1.40
) are used for the core and cladding, respectively, then from equation (2) NA=0.5, and from equation (1) the angle r=
It becomes 30°.

However, since the aperture angle is 30°, the diameter of the light beam emitted from the tip of the optical fiber will surely expand. Therefore, if the diameter of the optical fiber is about 85 μm, the gap between the optical fiber and the photosensitive drum is 5 μm.
If the thickness is not less than 0 μm, the image formed on the photosensitive drum will have so-called crosstalk due to interference between signals from adjacent optical fibers, resulting in deterioration of image quality.

Conventionally, it has been proposed to prevent crosstalk and deterioration of image quality by providing precise condensing lenses on the output end sides of each optical fiber.

[Problem to be solved by the invention]

However, if a condensing lens is provided for each optical fiber as described above, there are problems in that manufacturing is difficult and the cost increases.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to prevent the diameter of a light beam irradiated from an optical fiber bundle from expanding, and to prevent deterioration of image quality by preventing crosstalk. An object of the present invention is to provide a method for manufacturing an optical device that can easily manufacture an optical device that can perform the following steps on the output side of an optical fiber bundle.

[Means to solve the problem]

The present invention provides a method for manufacturing an optical device provided on the output side of an optical waveguide bundle made up of a plurality of optical waveguides, in which a filter whose light transmittance gradually increases from the center is attached to the output side of each optical waveguide. , the output end side is exposed to light so as to be photopolymerized, and then the residual monomer is removed.

[Effect]

A filter whose light transmittance gradually increases from the center is attached to the exit side of each optical waveguide forming the leading waveguide bundle. and,
In this state, the exit side is exposed to light for photopolymerization, and then the residual monomer is removed.

Then, an optical device is formed on the exit side of the leading waveguide.

The light emitted from the optical waveguide is focused by an optical device provided on the output end side of each optical waveguide. This results in
There is no quadroke in the emitted light, and deterioration of image quality can be prevented.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 shows a longitudinal sectional view of an optical scanning device of an image forming apparatus according to the present invention. Reference numeral 11 in the figure is a light source, and a condenser lens 12 is provided on the irradiation side of this light source 11. Furthermore, the entrance side of the optical waveguide 14 of the scanner 13 is provided on the irradiation side of the condenser lens 12 .

The optical waveguide 14 has a substantially L-shaped longitudinal section, and is embedded in the rotating body 15 so that the output side of the optical waveguide 14 emits light onto the circumferential side of the rotating body 15. Further, reference numeral 16 in the figure is a motor, and the rotating body 15
is driven to rotate at a constant speed. Further, on the output side of the optical waveguide 14, an optical fiber bundle 1 formed of a plurality of optical fibers is provided.
7 is provided with an entrance opening formed in an arc shape so as to surround the scanner 13. Here, a light condensing lens 18 is provided on the exit side of each optical fiber forming the optical fiber bundle 17. Further, a photosensitive drum 19 is provided on the exit side of the optical fiber bundle 17.

The operation of the optical scanning device configured in this way will be explained below.

An optical signal emitted from the light source 1 is input from the entrance side of the optical waveguide 14 via the condensing lens 12 . At this time, the rotating body 15 in which the optical waveguide l4 is embedded is driven by the motor 16.
It is driven to rotate by. In this state, the optical waveguide 1
The optical signal emitted from the output side of 4 is connected to the optical fiber bundle 17.
The light enters from the entrance side. At this time, as the rotating body 15 rotates, optical signals are sequentially input into each optical fiber. The optical signal scanned within the optical fiber bundle 17 is condensed by a light condensing lens 18 provided on the exit side of the optical fiber bundle 17, and then irradiated onto the photosensitive drum 19. As a result, the photosensitive drum 19 can be exposed for one line first. By sequentially repeating this operation, the photosensitive drum 9 can be exposed to an image. Since the optical signals irradiated onto the photosensitive drum 19 are thus focused, image deterioration due to crosstalk can be prevented.

Hereinafter, a method of manufacturing the optical fiber bundle 17 having the light condensing lens 18 at the exit portion used in the above embodiment by a photopolymerization method will be described with reference to FIGS. 2 and 3.

FIG. 2 is a diagram showing a method of manufacturing the optical fiber bundle 17 by a photopolymerization method, and FIG. 3 is a diagram showing a method of forming a light condensing lens 18 at the exit portion of each optical fiber of the optical fiber bundle 17. .

First, in order to create the base film 20, methyl acrylate, which is a photosensitizer, with a refractive index n2 = 1.48 is incorporated as a dope monomer into polycarbonate with a refractive index nl = 1.59, and a melt extrusion method (also called casting) is carried out. A sheet with a thickness of 50 to 100 μm is formed by this method (FIG. 2(a)).

Next, a mask 21 with a pattern that blocks light is placed on the sheet and exposed to ultraviolet light in the portion desired to be used as an optical waveguide. Only the exposed areas 22a caused by this exposure cause photopolymerization of the methyl acrylate, and the pattern of the mask 21 is transferred (FIGS. 2(b) and 3(a)).

At this stage, a filter 23 whose light transmittance gradually increases from the center is attached to the output end side of the unexposed portion 22b which is in an unpolymerized state. Then, UV exposure is performed in this state (FIG. 3(b)).

Then, a region where the degree of photopolymerization increases in the radial direction from the center appears at the output end of the unexposed portion 22b. That is, at the light emitting end, a region whose refractive index gradually decreases from the center toward the outer periphery is formed, and this region forms the light condensing lens 18 (see FIG. 3 (C)). )).

Next, by removing the remaining monomer in the unpolymerized unexposed portion 22b by vacuum drying, the unexposed portion 22b becomes only the base material polycarbonate, and the refractive index is 1.59.
It becomes the core part of. On the other hand, the refractive index of the exposed portion 22a decreases due to the above-mentioned photopolymerization reaction, so this portion becomes a cladding portion (FIG. 2(c)).

Then, as a final step, a low refractive index acrylic resin is coated as a cladding layer 24 in the vertical direction of the sheet (FIG. 2(d)).

By manufacturing as described above, it is possible to provide an optical fiber bundle 17 having a width and a height of approximately several tens of microns, and having a light condensing lens 18 formed on the light exit side.

As described above, by providing the light condensing lens 18 on the output side of the optical fiber bundle 17, the light emitted from the optical fiber bundle 17 is focused by the light condensing lens 18, so that the light emitted from the optical fiber bundle 17 is Even if the distance between the exit port and the photosensitive drum 19 is widened, crosstalk can be prevented and a good image can be obtained.

〔Effect of the invention〕

The present invention provides an optical device capable of preventing image deterioration due to crosstalk by manufacturing it as described above.
It can be manufactured easily and has the advantage of being able to reduce costs.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of the optical scanning device used in the image forming apparatus of the present invention, FIG. 2(a) is a diagram showing the state of preparation of the base film, and FIG. Figure 2 (c) shows the state of photopolymerization, Figure 2 (c) shows the state of removal of unreacted monomers, Figure 2 (d) shows the state of surface cladding, and Figure 3 (a) shows the state of mask exposure. Fig. 3(b) is a diagram showing a state in which a filter is attached to the output end side of the core section to emit UvI light, and Fig. 3(c) is a diagram showing the state of selective photopolymerization at the output end side of the core section. FIG. 4 is a perspective view of a conventionally commonly used optical scanning device, and FIG. 5 is a longitudinal sectional view of a conventionally commonly used optical scanning device. 1l... Light source, 17... Optical fiber bundle (optical waveguide bundle), 18... Light condensing lens (optical device).

Claims (1)

[Claims] In a manufacturing method of an optical device provided on the output side of an optical waveguide bundle made up of a plurality of optical waveguides, a filter whose light transmittance gradually increases from the center is attached to the output end side of each of the optical waveguides, and the output end 1. A method of manufacturing an optical device, which comprises exposing the part side to light so as to photopolymerize it, and then removing residual monomer.