JPH03200918A - Synchronism detecting device for optical scanner - Google Patents

Abstract

PURPOSE:To reduce the formation of a ghost image and to increase the degree of freedom of the design of an optical system by arranging an optical fiber and a photoelectric converting element so that the center axis of the optical fiber at its projection and, and the photodetection surface of the photoelectric converting element do not intersect at right angles each other, and isolated by more than the optical transmission diameter of the optical fiber. CONSTITUTION:The center axis C of the optical fiber 7 at its projection end 7b and the photodetection surface 8a of the photoelectric converting element 8 are slanted relatively and arranged not to intersect at right angle each other, or the projection end 7b of the optical fiber 7 and the photodetection surface 8a of the photoelectric converting element 8 are isolated by more than the optical transmission diameter of the optical fiber 7. Consequently, much of reflected light Ld from the photodetection surface 8a of the photoelectric converting element 8 is emitted out of the optical fiber 7 and the rate of traveling toward the incidence end 7a decreases. Consequently, the formation of a ghost image is reducible. Further, the mean angle of incidence on a deflector from a light source unit need not be limited unlike before, so the degree of freedom of the design of the optical system never becomes small.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a synchronization detection device used in an optical scanning device, and more particularly to prevention of ghost images caused by diffusely reflected flare light in the synchronization detection device.

[Conventional technology]

As a conventional optical scanning device, there is one shown in FIG. 5, for example. In the figure, a light beam L from a device consisting of a light source, a condensing device, etc. is transmitted through a line image forming system 2 (such as a cylindrical lens) (
The light beam passes through the first imaging optical system (first imaging optical system), enters one reflection surface 3a of the deflector 3 constituted by a rotating polygon mirror, and is formed into a linear image. The luminous flux L is reflected by the reflecting surface 3a, and the spherical single lens 4,
and a single lens 5 having a toric surface with different refractive powers in two orthogonal directions. form. This imaged spot is formed on the photoreceptor surface 6 in the main scanning direction (in the direction of the arrow in the figure) as the deflector 3 rotates.
The image will be scanned at a constant speed.

An input end 7a of an optical fiber 7 is arranged near the photoreceptor surface 6 at a position substantially equivalent to the photoreceptor surface 6, and an image of the light beam is formed on the input end surface of the optical fiber 7, as shown in FIG. A spot is incident. In the figure, reference numeral 11 is a cylinder lens for synchronization.

As shown in FIG. 7, the output end 7b of the other end of the optical fiber 7
A photoelectric conversion element 8, which together with the optical fiber 7 constitutes a synchronization detection device, is provided with its light-receiving surface 8a in contact with the photoelectric conversion element 8. In this synchronous detection device, an imaged spot of a bundle of light entering from an input end 7a of an optical fiber 7 is transmitted through the optical fiber 7 while being reflected by its peripheral wall surface, and is emitted from an output end 7b, which is converted into a photoelectric converter. Light is received and detected by the light receiving surface 8a of the element 8, and the photoelectric conversion element 8 converts it electrically and outputs a detection signal so that the optical scanning device can synchronize the timing for starting the deflection scan. It has become.

The optical fiber 7 has the advantage that it can transmit light more efficiently over a longer distance than a lens, and because it has flexibility, it has a greater degree of freedom in its layout. Photoelectric conversion element 8
A light receiving element such as a photodiode is used.

[Problem to be solved by the invention]

However, in such a conventional optical scanning device, as shown in FIG. Although the light is repeatedly transmitted to the output end 7b side, the optical fiber 7 and the photoelectric conversion element 8 are arranged so that the central axis at the output end 7b of the optical fiber 7 and the light receiving surface 8a of the photoelectric conversion element 8 are orthogonal to each other. Therefore, the incident light La
A part of the light hits the light receiving surface 8a of the photoelectric conversion element 8 and is diffusely reflected, and the reflected light Lb passes through the optical fiber 7 again and returns to the incident end 7a side. This reflected light Lb returns to the incident end 7.
a (diffuse reflected flare light) and enters the single lens 5 of the imaging optical system as shown in FIG.
is further reflected by the reflective surface 3b next to the reflective surface 3a of the deflector 3 used for deflection scanning, and is again reflected by the single lens 5.
Therefore, a ghost image may be formed on the photoreceptor surface 6 and disturb the original image on the photoreceptor surface 6.

Japanese Patent Laid-Open No. 58-68014 proposed a scanning optical system for removing ghost images caused by similar causes.
There is a device published in the above publication, in which the average incident angle to the deflector 3 is limited so that the light that generates a ghost image does not form an image on the photoreceptor surface 6 again. This has the problem that the degree of freedom in designing the optical system is reduced.

Therefore, it is an object of the present invention to solve the above problems.

[Means to solve the problem]

In order to solve the above problems, the present invention has the following configuration.

(1> A synchronization detection device used in an optical scanning device and synchronized by guiding synchronization light to a photoelectric conversion element 8 through an optical fiber 7, in which the central axis C at the output end 7b of the optical fiber 7 and the photoelectric conversion element 8 are synchronized. The conversion element 8 is arranged so as to be relatively inclined so that the light receiving surface 8a is not perpendicular to the light receiving surface 8a.

(2) A synchronization detection device that is used in an optical scanning device and is synchronized by guiding synchronization light to a photoelectric conversion element 8 through an optical fiber 7, which connects the output end 7b of the optical fiber 7 and the photoelectric conversion element 8. The distance between the light receiving surface 8a and the light receiving surface 8a is equal to or more than the optical transmission diameter of the optical fiber 7.

[For production]

According to the synchronization detection device of the optical scanning device having such a configuration,
The central axis C at the output end 7b of the optical fiber 7 and the light-receiving surface 8a of the photoelectric conversion element 8 may be arranged at a relative inclination so that they are not perpendicular to each other, or the output end 7b of the optical fiber 7 and the light-receiving surface of the photoelectric conversion element 8 may be 8a is separated by at least the optical transmission diameter of the optical fiber 7, most of the reflected light Lb reflected by the light-receiving surface 8a of the photoelectric conversion element 8 is dissipated to the outside of the optical fiber 7 and travels in the direction of the incident end 7a. As a result, the occurrence of ghost images on the photoreceptor surface 6 can be reduced.

〔Example〕

Hereinafter, actual tumor examples of the present invention will be explained based on the drawings. FIG. 1 is a diagram showing a first embodiment of a synchronization detection device for an optical scanning device according to the present invention, and a description of the structure similar to that of the conventional example will be omitted.

In the figure, the output @7b surface of the optical fiber 7 is cut obliquely, and the output @7b which is formed obliquely
A photoelectric conversion element 8 is provided in contact with a light receiving surface 8a. That is, the central axis C of the output end 7b of the optical fiber 7 and the light-receiving surface 8a of the photoelectric conversion element 8 are arranged so as to be inclined relative to each other so as to form an angle α (approximately 45°) so as not to be orthogonal to each other.

The optical fiber 7 and the photoelectric conversion element 8 together constitute a synchronization detection device. That is, the incident light a that has entered the input end 7a of the optical fiber 7 is repeatedly reflected from the peripheral wall surface inside the optical fiber 7, is transmitted to the output 1Ii7b side, is emitted from the output end 7b, and is transmitted to the light receiving surface 8a. The light is guided to the photoelectric conversion element 8 to be received. The light receiving surface 8a of the photoelectric conversion element 8 detects the incident light La, and the photoelectric conversion element 8 electrically converts the detected light and outputs a detection signal, which causes the optical scanning device to determine the synchronization timing for starting deflection scanning. It is now possible to take it.

In such a synchronization detection device for an optical scanning device, the incident light La from the incident end 7a is incident on the inner wall surface of the optical fiber 7 at an acute angle, and the incident light La passes through the optical fiber 7. The incident light La is reflected by the light-receiving surface 8a of the photoelectric conversion element 8, and most of the reflected light Lb is diffused to the outside of the optical fiber 7 (to the right in the figure) as shown in the figure, and is emitted @ The reflected light Lb that enters the optical fiber 7 again from 7b is small, and the reflected light Lb that travels in the direction of incidence @ 7a and heads toward the deflector 3 is also small, which prevents the generation of ghost images on the photoreceptor surface 6. can be reduced.

In addition, in an optical scanning device having such a synchronization detection device, there is no need to limit the average angle of incidence from the light source device 1 to the deflector 3 as in the conventional example, so the degree of freedom in designing the optical system is reduced. Furthermore, since no other parts or devices are required, the optical system does not become large.

2 and 3 show a second embodiment of the invention. In this second embodiment, as shown in FIG. 2, the surface of the output end 7b of the optical fiber 7 and the light receiving surface 8a of the photoelectric conversion element 8 are separated by the optical transmission diameter of the optical fiber 7 or more. That is, as shown in FIG. 3, the output fIIA7 of the optical fiber 7
b and the light receiving surface 8a of the photoelectric conversion cable 8 are separated by h, and this h has a relationship of h≧d with respect to the optical transmission diameter d of the optical fiber 7. Generally, the emitted light from the optical fiber 7 has a spread angle θ, and this spread angle θ is θ〉45
It is said that the typical value is θ-53° (optical technology handbook, p. 380, Asakura Shoten edition), assuming that the light emitted from the optical fiber 7 has a uniform light intensity distribution. , the diameter B of the luminous flux at the light receiving surface 8a of the photoelectric conversion element 8 is B = d + 2 h tan θ. The photoelectric conversion element 8 receives the spread light beam on its light-receiving surface 8a and outputs an integral value of approximately the entire light amount. There is no effect on the synchronization detection accuracy even if the distance between the two is more than the optical transmission diameter of the optical fiber 7.
On the same plane as , the luminous flux diameter A is A = d + 4 h
tan θ or more (due to diffusion).

As a result, the light beam that enters the output end 7b of the optical fiber 7 again has a reflectance of 100% on the light receiving surface 8a of the photoelectric conversion element 8.
Even if the reflected light Lb is d2/A2, h=d, θ=
When the angle is set to 45°, the value becomes 1/25. For this reason,
Most (24/25) of the reflected light Lb reflected by the light-receiving surface 8a of the photoelectric conversion element 8 is outside the optical fiber 7! I
(radius outward) and exits fl! The reflected light Lb that enters the optical fiber 7 again from 1f7b is only (1/
25), and the generation of ghost images on the photoreceptor surface 6 can be greatly reduced.

FIG. 4 shows a third embodiment of the present invention. This third embodiment is similar to the first embodiment described above. This embodiment is based on the idea of the second embodiment. That is, the central axis C of the output end 7b of the optical fiber 7 and the light receiving surface 8a of the photoelectric conversion element 8 are arranged so as to be inclined relative to each other, and the output end 7b of the optical fiber 7 and the photoelectric conversion element 8 are arranged so as to be inclined relative to each other.
The light receiving surface 8a is separated from the light receiving surface 8a. According to this third embodiment, the above-mentioned first. Due to the synergistic effect of the second example, it is possible to almost prevent the reflected light Lb from entering the optical fiber 7 again, and more reliably prevent the generation of ghost images on the photoreceptor surface 6.

〔Effect of the invention〕

As explained above, according to the present invention, the center axis at the output end of the optical fiber and the light receiving surface of the photoelectric conversion element are arranged at a relative inclination so that they are not perpendicular to each other, or the output end of the optical fiber and the photoelectric conversion element Since the light-receiving surface of the charge conversion element is separated from the light-receiving surface of the optical fiber by more than after the light is transmitted, most of the reflected light reflected by the light-receiving surface of the charging conversion element is dissipated to the outside of the optical fiber, and a small proportion of the light travels toward the input end. The generation of ghost images on the photoreceptor surface can be reduced.

In addition, in an optical scanning device having such a synchronization detection device, there is no need to limit the average angle of incidence from the light source device to the deflector as in the conventional example, so the degree of freedom in designing the optical system is not reduced. Moreover, since no other parts or devices are particularly required, the optical system does not become large.

[Brief explanation of drawings]

FIG. 1 shows a first synchronization detection device for an optical scanning device according to the present invention.
Enlarged diagram of an optical fiber and photoelectric conversion element showing an actual example, Part 2
FIG. 3 is a diagram showing a second embodiment of the present invention,
Figure 2 is an enlarged view of the optical fiber and photoelectric conversion element, Figure 3 is a conceptual diagram of incident light from the output end of the optical fiber and reflected light reflected by the light receiving surface of the photoelectric conversion element, and Figure 4 is the invention of the present invention. 5 to 7 are diagrams showing a conventional optical scanning device, FIG. 5 is an overall perspective view of the optical scanning device, and FIG. The figure is a partially enlarged plan view of the optical scanning device showing how a ghost image is formed on the surface of the photoreceptor, and FIG. 7 is an enlarged view of the optical fiber and the photoelectric conversion element.

Claims (2)

[Claims] (1) A synchronization detection device used in an optical scanning device and synchronized by guiding synchronization light to a photoelectric conversion element through an optical fiber, the central axis at the output end of the optical fiber and the light-receiving surface of the photoelectric conversion element. What is claimed is: 1. A synchronization detection device for an optical scanning device, characterized in that the devices are arranged at a relative inclination so that they are not orthogonal to each other. (2) A synchronization detection device used in an optical scanning device, which synchronizes by guiding synchronization light to a photoelectric conversion element through an optical fiber, and which connects the output end of the optical fiber and the light-receiving surface of the photoelectric conversion element with light. A synchronization detection device for an optical scanning device, characterized in that the separation is equal to or longer than the optical transmission diameter of a fiber.