JPH03171026A - Optical scanner - Google Patents

Abstract

PURPOSE:To miniaturize the scanner and to improve the efficiency thereof by providing an inner hollow member having a slit in an axial line direction and a turnable outer hollow member having a spiral slit. CONSTITUTION:A light source 8 is housed on the inner side of the inside cylindrical member 9. This inside cylindrical member 9 is provided with the slit 9a extending in the axial line direction and an optical sensor 10 which detects the light exit position is disposed at one end part of the slit 9a. The turnable outside cylindrical member 11 is provided in the outer part of the inside cylindrical member 9. This outside cylindrical member 11 is provided with the spiral slit 11a. An imaging lens 12 for condensing and imaging exit light is provided on the slit 9a side of the inside cylindrical member 9. A photosensitive member 13 is turnably provided on the irradiation side of the imaging lens 12. Since the optical path is shortened in this way, the optical path loss is decreased and the size of the scanner is reduced; in addition, the efficiency is enhanced.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an optical scanning device in an image forming apparatus.

[Conventional technology]

2. Description of the Related Art In recent years, image forming apparatuses have been known that form images by scanning image signals (by exposing a photosensitive member to light) using optical fibers.

FIG. 5 is a diagram showing a commonly used optical scanning device. Reference numeral 1 in the figure is a semiconductor laser, and this semiconductor laser 1 generates a laser beam modulated by an LDRV (not shown). A collimator lens 2 and a cylindrical lens 3 are provided on the irradiation side of the laser beam, and the collimator lens 2 and the cylindrical lens 3 convert the laser beam from the semiconductor laser 1 into a parallel beam. This collimator lens 2
The laser beam, which is made into a parallel beam by the cylindrical drill lens 3, is further incident on a polygon mirror 4. This polygon mirror 4 has a polygonal prism shape and is deflected at a constant speed, thereby deflecting the parallel beam at a constant angular velocity.

Furthermore, the laser beam deflected by the polygon mirror 4 is focused by the f-theta lens 5, and then reaches the reflection mirror 6, and then passes through the reflection mirror 6 onto the photosensitive drum 7, which rotates at a constant speed. An image is formed along a straight line D parallel to the rotation axis.

[Problem to be solved by the invention]

However, since the optical path is bent by a polygon mirror or a reflective mirror, a relatively long optical path is required, resulting in large optical path loss and difficult to align the optical axis. Also, collimator lenses, cylindrical lenses and f-
Lenses such as θ lenses are very expensive, and there is a problem in that the cost of the entire device increases.

The present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a small, efficient, and inexpensive optical scanning device that does not use expensive lenses, mirrors, etc.

[Means to solve the problem]

In the present invention, an inner hollow member having an axial slit is fixedly disposed, the inner hollow member is covered with a rotatable outer hollow member having a spiral slit, and a light source is provided inside the inner hollow member. is disposed, and a photosensitive member is disposed on the opposite side of the inner hollow member, facing the outer hollow member.

[Effect]

The light source is turned on and the outer hollow member is rotated. Then, the light emitted from the light source first passes through the axial slit provided in the inner hollow member. The light that has passed through this slit further passes through a spiral slit provided in the rotating outer hollow member.

At this time, objects that pass through the slits in the inner hollow member but do not pass through the slits in the outer hollow member are shielded. The light passing through the slit in the outer hollow member exposes the exposure member.

〔Example〕

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

FIG. 1 is a schematic diagram of an optical scanning device according to the present invention. Reference numeral 8 in the figure is a light source, and this tip source 8 is housed inside the inner cylinder member 9. FIG. 2 is a perspective view of this inner cylinder member 9. This inner cylinder member 9 has a slit 9 extending in the axial direction.
A is provided.

Further, an optical sensor 10 for detecting the light emission position is provided at one end of the slit 9a. As shown in FIG. 1, a rotatable outer cylinder member 11 is provided on the outer side of the inner cylinder member 9. As shown in FIG. FIG. 3 is a perspective view of this outer cylinder member 11.

As shown here, this outer cylinder member 11 is provided with a spiral slit lla. Further, an imaging lens 12 for condensing and imaging the emitted light is provided on the slit 9a side of the inner cylinder member 9, and furthermore, this imaging lens 12
A photosensitive drum 13 is rotatably provided on the irradiation side. Further, the outer cylinder member 11 is driven by a drive device 14. Note that the reference numeral 15 in the figure is a control circuit, which controls the light source 8, drive device 14, and the like.

The operation of the optical scanning device configured as described above will be explained below.

The light source 8 is blinked while being controlled by the control circuit 15. On the other hand, the drive device {4 is controlled and driven by the control circuit 15, and the outer cylinder member 11 is rotated. Then, first, the optical signal emitted from the light source 8 is transmitted to the inner cylinder member 9.
is irradiated. Then, the slit 9a of this inner cylinder member 9
An optical signal is emitted from the Furthermore, the optical signal emitted from this slit 9a is irradiated onto the outer cylinder member l1. The optical signal irradiated onto the outer cylinder member 11 is emitted to the outside of the outer cylinder member 1l through a spiral slit lla formed in the outer cylinder member l1. At this time, the optical signal from the light source 8 is transmitted through the slit 9a of the inner cylinder member 9 and the slit 11 of the outer cylinder member 11.
Only the optical signal that has passed through both a is emitted to the outside of the outer cylinder member 11, and the emitting position can be determined.

At this time, since the outer cylinder member 11 is rotated by the drive device 14, the emission position sequentially moves in the axial direction since the slit lla of the outer cylinder member 11 is formed in a spiral shape. . The optical signal emitted from the outer cylinder member 11 spreads and travels due to the diffraction phenomenon caused by the slits 9a and lla, but after being focused by the imaging lens 12, it is irradiated onto the photosensitive drum 13 and exposed. It is done.

That is, by one rotation of the outer cylinder member (1), the exposure position is sequentially moved, and the photosensitive drum 13 can be exposed for one line. Furthermore, by sequentially repeating this operation, image information can be input to the photosensitive drum 13.

4 is a block diagram showing the flow of control signals within the control circuit 15. As shown in FIG. Here, the CPU 16 clocks the screen information 18 to a clock 19 in synchronization with the optical sensor signal 17.
and sends it to the driver circuit 20 for driving the light source 8.

〔Effect of the invention〕

By configuring the present invention as described above, the optical path can be shortened, so the optical path loss is small, the optical axis alignment is easy, and the efficiency is high. Furthermore, since the structure does not require an expensive lens, it can be implemented at low cost.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an optical scanning device according to the present invention, FIG. 2 is a perspective view of an inner cylinder member used in the optical scanning device according to the present invention, and FIG. FIG. 4 is a block diagram showing the flow of control signals in the control circuit of the optical scanning device according to the present invention, and FIG. 5 is a schematic diagram of a commonly used optical scanning device. 8... Light source, 9... Inner tube member (inner hollow member), 9a... Slit, 11... Outer tube member (outer hollow member), 11a... Slit.

Claims (1)

[Claims] An inner hollow member having an axial slit is fixedly disposed, the inner hollow member is covered with a rotatable outer hollow member having a spiral slit, and a light source is disposed inside the inner hollow member. In addition, an optical scanning device characterized in that a photosensitive member is disposed on the opposite side of the inner hollow member so as to face the outer hollow member.