JPH0385510A - Synchronization detector for optical scanner - Google Patents

Abstract

PURPOSE:To prevent the occurrence of a ghost image due to image formation of reflected light on the photosensitive body surface by holding the incidence end of an optical fiber on the inside of the end face where the hole of a holding member is opened. CONSTITUTION:A holding member 10 is provided whose hole 10a an incidence end 7a of an optical fiber 7 on which synchronous light La is made incident is fitted to and held in, and the incidence end 7a of the optical fiber 7 is held on the inside of an end 10b where the hole 10a of the holding member 10 is opened. Consequently, reflected light Lb from the incidence end 7a of the optical fiber 7 passes the hole 10a of the holding member 10 and has the peripheral edge part cut and is shaped to a narrow form and is emitted from the hole 10a of the holding member 10. Thus, the diffuse range of the reflected light is narrowed, and the reflected light is prevented from forming an image on the photosensitive surface as the conventional to cause a ghost image.

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. 9, 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 passes through the spherical single lens 4.
, and a single lens 5 having a toric surface with different refractive powers in two orthogonal directions.
The light is incident on the photoreceptor surface 6 through an imaging optical system (imaging optical system) to form an imaging spot. 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.

A photoelectric conversion element (not shown), which together with the optical fiber 7 constitutes a synchronization detection device, is provided at the output end of the other end of the optical fiber 7 . In this synchronous detection device, an imaged spot of a bundle of light incident from the input end 7a of the optical fiber 7 is transmitted through the optical fiber 7 while being reflected by its peripheral wall surface, and is emitted from the output end, and is transferred to a photoelectric conversion element. receives and detects light, converts it electrically and outputs a detection signal,
The optical scanning device is capable of synchronizing the start of the deflection scanning described above.

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.

[Problem to be solved by the invention]

However, in such a conventional optical scanning device, a part of the incident light La entering from the input end 7a of the optical fiber 7 hits the input surface f) if 7 a of the optical fiber 7 and is diffusely reflected. , the reflected light Lb (diffuse flare light) is transmitted through the single lens 5 of the imaging optical system as shown in FIG.
The light enters the lens, passes through the single lens 5, 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 imaged on the photoreceptor surface 6 by the single lens 5. A ghost image may be formed that disturbs 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-mentioned problems, the present invention provides a synchronization detection device that is used in an optical scanning device and is synchronized by guiding synchronization light La to a photoelectric conversion element 8 through an optical fiber 7. A holding member 10 is provided which fits and holds the input end 7a of the optical fiber 7 into the hole 10a, and the input @7a is connected to the end face 1 where the hole 10a of the holding member 10 opens.
The optical fiber 7 is configured such that it is held in a state that it is inserted inside the optical fiber 7, and further, the axis C1 of the input end of the optical fiber 7 is
It is arranged so as to be inclined with respect to the axis C2 of the hole 10a from the end surface 10b of the holding member 10 to the input end 7a of the optical fiber 7.

[For production]

According to the synchronization detection device of the optical scanning device having such a configuration,
The input end 7a of the optical fiber 7 into which the synchronizing light La is input is connected to the hole 1.
A holding member 10 is provided to fit and hold the optical fiber 7.
Since the incident end 7a of the optical fiber 7 is held in a state inside the end surface 10b where the hole 10a of the holding member 10 opens, the reflected light Lb from the incident end 7a of the optical fiber 7 passes through the hole 10a of the holding member 10. By passing through, the reflected light Lb is shaped into a thin shape so that most of its peripheral edge is shaved off, and is emitted from the hole 10a of the holding member 10, so that the diffusion range of the reflected light Lb becomes narrower, and the reflected light Lb becomes narrower. It is possible to prevent a ghost image from being formed on the photoreceptor surface 6 as in the conventional example described above.

Further, since the axis C1 of the input end 7a of the optical fiber 7 is arranged at an angle with respect to the axis C2 of the hole 10a from the end surface tob of the holding member 10 to the input end 7a of the optical fiber 7,
Since most of the reflected light Lb from the input end 7a of the optical fiber 7 hits the wall surface of the hole 10a of the holding member 10 and is blocked, the reflected light Lb emitted from the hole 10a of the holding member 10
can be significantly reduced, and the generation of ghost images formed on the photoreceptor surface 6 can be more reliably prevented.

〔Example〕

Embodiments of the present invention will be described below 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 input end 7a of the optical fiber 7 into which the synchronization light La is input is held by being fitted into a hole 10a of a holding member 10 fixed to a stationary part of the optical scanning device. The input end 7a of the optical fiber 7 is held inside the holding member 10 from the end surface 10b where the hole 10a opens. The circumference of the optical fiber 7 is covered with a cover 1 to prevent stray light.
2. A light receiving surface 8a of a photoelectric conversion element 8 is arranged near the output end 7b of the optical fiber 7.

The photoelectric conversion element 8 and the optical fiber 7 together constitute a synchronization detection device. That is, the synchronized light La that has entered the input end 7a of the optical fiber 7 is repeatedly reflected from the peripheral wall inside the optical fiber 7, is transmitted to the output end 7bl) 1, 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 so that the light is received. The light receiving surface 8a of the photoelectric conversion element 8 detects the synchronized light La, and thereby the photoelectric conversion element 8
The optical scanning device can synchronize the start of deflection scanning by the detection signal that is output by electrically converting the detection light.

In such a synchronization detection device for an optical scanning device, the synchronization light La passes through the hole 10a of the holding member 10 and is connected to the optical fiber 7.
At this time, a part of the incident light La hits the surface of the input end 7a of the optical fiber 7 and is diffusely reflected, and the reflected light b is reflected again on the photoreceptor surface 6 as described above.
There is a risk that an image will be formed on top of the object, forming a ghost image. However, according to the above embodiment, since the input end 7a of the optical fiber 7 is held inside the end face 10b where the hole 10a of the holding member 10 opens, the input end 7a of the optical fiber 7 is When the reflected light Lb passes through the hole 10a of the holding member 10, the hole 1 of the holding member 10 is shaped into a thin shape so that most of the peripheral edge of the reflected light Lb is shaved off.
By being emitted from 0a, the diffusion range of the reflected light Lb is narrowed, and it is possible to prevent the reflected light Lb from forming an image on the photoreceptor surface 6 and generating a ghost image as in the conventional example described above. can.

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.

FIG. 2 shows a second embodiment of the present invention. In this second embodiment, as shown in the figure, the input end 7a of the optical fiber 7 is aligned on the same plane as the end surface of the end 12a of the cover 12. However, the hole 10a of the holding member 10 has the same diameter as the optical fiber 7 as in the first embodiment. The second embodiment can also achieve the same effects as the first embodiment, and the length of the holding member 10 can be made shorter than that of the first embodiment, making the parts smaller and lighter. and even cost reductions.

3 to 6 show a third embodiment of the present invention. As shown in FIG. 3, this third embodiment includes a Hole 1 of holding member 10
The diameter φA of the optical fiber 0a is smaller than the diameter φB of the optical fiber 7.

That is, two types of holes with a diameter φB and a diameter φA are formed on the same axis in the holding member 10, and among these, the hole with a diameter φB has a diameter φ
The position of the optical fiber 7 B is determined by inserting it until it hits the stepped portion where the diameter changes.

In this way, by making the diameter φA of the hole 10a of the holding member 10 smaller than the diameter φB of the optical fiber 7, the reflected light L
The peripheral edge of the light beam b is shaved more than in the case of the embodiment described above, and is further shaped into a thinner shape before being emitted from the hole 10a of the holding member 10, so that the diffusion range of the reflected light Lb is further narrowed, and the reflected light Lb is It is possible to more reliably prevent the formation of an image on the photoreceptor surface 6 and the generation of a ghost image as in the conventional example described above, compared to the case of the aforementioned embodiment.

That is, as shown in FIG. 4, the reflected light Lb at the input end 7a of the optical fiber 7 has a light intensity distribution as shown by a curve S. In other words, as shown in FIG. If this light intensity distribution is shown according to changes in the angle θ from the axis C, a graph as shown in FIG. 5 will be obtained. In FIG. 4, the distance from the input end 7a of the optical fiber 7 to the end surface 10b of the holding member 10 is 1, and the hole 1 of the holding member IO is 1.
When the diameter of 0a is φA, the reflected light L from the incident end 7a
The angular range from the axis C in which b is ejected from the hole 10a is:
O≦θ≦tan” (φA/2j).The smaller θ is, the smaller the amount of reflected light Lb emitted from the hole 10a is. The diameter φA of the optical fiber 7 is preferably smaller than the diameter φB of the optical fiber 7, as described above.

In FIG. 6, the beam diameter at the input end 7a of the optical fiber 7 is generally about several tens to 150 μm, and the diameter φB of the optical fiber 7 is about 0.5 to 1 mm. The beam diameter at the input end 7a of the optical fiber 7 is VVo, and the beam diameter at the end surface 10b of the hole 10a of the holding member 10 is W.
Then, it can be expressed as. However, λ is the wavelength.

Moreover, as shown in FIG. 5, at least about 1 of the reflected light Lb
In order to be able to reduce /4, it is desirable to set θ to θ minus 10°.

In other words, if we replace the graph curve in the same figure with an equivalent straight line, the area of the part larger than 10° is about 1/4 of the whole.
This is because.

7 and 8 show a fourth embodiment of the present invention. In this fourth embodiment, as shown in FIG. 7, the axis C1 of the input end 7a of the optical fiber 7 is Axis line C2 of the hole 10a from 10b to the input end 7a of the optical fiber 7
It is placed at an angle to the According to this fourth embodiment, since most of the reflected light Lb from the input end 7a of the optical fiber 7 hits the wall surface of the hole 10a of the holding member 10 and is blocked, the reflected light emitted from the hole 10a of the holding member 10 By significantly reducing Lb, it is possible to more reliably prevent the formation of ghost images on the photoreceptor surface 6.

That is, in FIG. 8, the input end 7a of the optical fiber 7
If the angle between the axis C1 of the holding member lO and the axis C2 of the hole 10a of the holding member lO is ψ, the reflected light L is a part of the synchronizing light La from the direction of the axis C2 of the hole 10a reflected by the incident end 7a.
b proceeds primarily in the direction of an angle 2ψ with respect to the axis ali C2. Here, the angle θ formed by the straight line E connecting the synchronization detection position (center position) of the input end 7a of the optical fiber 7 and the edge of the end surface 10b of the hole 10a of the holding member 10 with the axis C2 is θo-tan. (φA/21>, so the angle α between the traveling direction of the reflected light Lb and the straight line E is α-2ψ-θo=2ψ-tan-' (φA/24!
>, from this angle α, only the reflected light Lb that protrudes from the straight line E toward the axis C2 side is emitted from the hole 10a to the outside, so if the angle α is made large, the reflected light Lb emitted to the outside
can reduce the amount of

Therefore, for this purpose, if the angle ψ is made large, the amount of reflected light Lb emitted to the outside can be reduced; however,
If the angle ψ is increased to 45° or more, the amount of synchronization light La incident on the inside of the optical fiber 7 will decrease, which will impede synchronization detection. Therefore, the angle ψ will be increased by 5° to 45°.
It is desirable to set the angle φ to approximately 1, and it is sufficient to set φA and 1 together with such an angle φ.

For example, using the optical fiber 7 having the light intensity characteristics as shown in FIG. 5, in order to obtain the amount of reflected light Lb equivalent to when θ=10° under the same conditions as in FIG. 4, ψ= 5',
φA=0.8mm, j! =3mm. At this time,
The angle θo = 2α = 2ψ - θo = 8°, so 8° of α
The reflected light Lb from the inner part is further reduced, and the reflected light Lb which protrudes to the outer part from 8 degrees of α (from the above-mentioned direct +IiE) is emitted to the outside from the hole 10a. Also, ψ=lO°, φ
If A=0.5mm and 1=5mm, angle α=14
°, 2ψ - α = 6°, the reflected light Lb inside 14° of α is reduced, and the reflected light Lb that protrudes to the outside from 14° of α (from the straight line E) is emitted to the outside from the hole 10a. Ru. Therefore, most of the reflected light Lb can be reduced.

〔Effect of the invention〕

As explained above, according to the present invention, since the input end of the optical fiber is held in a state inside the end face where the hole of the holding member opens, the reflected light from the input end of the optical fiber is retained. By passing through the hole in the member, the reflected light is shaped into a thin shape so that most of its peripheral edge is shaved off, and then emitted from the hole in the holding member, which narrows the diffusion range of the reflected light and causes the reflected light to have the same shape as described above. It is possible to prevent a ghost image from being formed on the photoreceptor surface as in the conventional example.

In addition, since the axis of the input end of the optical fiber is arranged at an angle with respect to the axis of the hole from the end surface of the holding member to the input end of the optical fiber, most of the reflected light Lb from the input end of the optical fiber is retained. Since the light hits the wall of the hole in the member and is blocked, the reflected light emitted from the hole in the holding member is significantly reduced, and it is possible to more reliably prevent the formation of a ghost image on the surface of the photoreceptor.

Furthermore, 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 reduced. Moreover, since no other parts or devices are 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.
An enlarged view of an optical fiber and a holding member showing an embodiment, FIG. 2 is an enlarged view of a holding member showing a second embodiment of the present invention, and FIGS. 3 to 6 are views showing a third embodiment of the present invention. and the third
The figure is an enlarged view of the holding member, Figure 4 is a conceptual diagram showing the light intensity distribution of the reflected light, Figure 5 is a graph showing the light intensity characteristics of the optical fiber, and Figure 6 is the beam diameter of the reflected light at each position. The enlarged views of the holding member shown in FIGS. 7 and 8 are the fourth embodiment of the present invention.
7 is an enlarged view of the optical fiber and the holding member, FIG. 8 is a conceptual diagram showing the light intensity distribution of reflected light,
9 and 10 are diagrams showing a conventional optical scanning device. FIG. 9 is an overall perspective view of the optical scanning device, and FIG. 10 is a diagram of the optical scanning device showing how a ghost image is formed on the surface of a photoreceptor. FIG. 3 is a partially enlarged plan view.

Claims (2)

[Claims] (1) A synchronization detection device used in an optical scanning device, in which synchronization light is guided to a photoelectric conversion element through an optical fiber to achieve synchronization, and the input end of the optical fiber into which the synchronization light is input is fitted into a hole. 1. A synchronization detection device for an optical scanning device, characterized in that a holding member is provided, and the incident end is held in a state inside an end face of the holding member in which a hole is opened. (2) The optical fiber according to claim 1, wherein the axis of the input end of the optical fiber is arranged at an angle with respect to the axis of the hole from the end face of the holding member to the input end of the optical fiber. Synchronization detection device for optical scanning device.