JPH04166811A - Light scanning device - Google Patents

Abstract

PURPOSE:To arrange a rotary polygon mirror and an imaging lens in proximity to each other by arranging the imaging lens in the vicinity of a deflecting means to input a laser beam from the deflecting means, in an internal side surface of a cover. CONSTITUTION:Optical parts of a rotary polygon mirror device 5, imaging lens, that is, ftheta lens 7, reflecting mirror 9, second cylindrical lens 11, etc. are provided on an optical base 3, and a cover 13 is mounted by coating these optical parts. That is, the ftheta lens 7 is mounted to an upper part inside of the cover 13 by a lens supporting part 25. In this way, the ftheta lens 7 can be arranged in the vicinity a rotary polygon mirror 22 to receive laser light, reflected by a mirror surface, without being obstructed by a motor flange part 24.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an optical scanning device used in a laser printer or the like.

[Prior Art] Conventionally, in an optical scanning bag holder used in a laser printer or the like, various optical components have been placed together on a base of an optical device. For example, on the same plane on the base, a rotating polygon mirror device that drives a rotating polygon mirror by a motor, an imaging lens that introduces light from a single-rotation pot mirror and forms an image, and reflects the light from the imaging lens. Components such as a reflective mirror are housed therein, and these optical components are regulated and arranged by respective positioning protrusions provided on the base.

Additionally, the top of this base is designed to prevent dust and toner from entering the optical device and adhering to and contaminating the surfaces of lenses and mirrors, or to prevent unnecessary light from entering from outside. In order to do this, a light-shielding cover was provided to cover the optical components (see Japanese Patent Laid-Open No. 64-46713).

[Problems to be Solved by the Invention] However, in the case where the rotating polygon mirror device and the imaging lens are mounted on the same plane on the base, as shown in FIG. The motor flange portion P2 of the mirror device P and the positioning protrusion P of the imaging lens P3
4 interferes, so there is a problem that the imaging lens P3 cannot be mounted close to the transition surface mirror P5.For this reason, the imaging lens P3 cannot be made smaller, and therefore the optical device becomes large, making it difficult to keep costs low.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an optical scanning device in which a rotating polygon mirror and an imaging lens can be disposed close to each other.

[Means for Solving the Problems] In order to achieve this object, the present invention provides a light source that irradiates a laser beam, a deflection means that deflects and scans the laser light in a predetermined direction, and a method using the deflection means. An optical scanning device in which an optical mechanism including an imaging lens system that focuses deflected laser light on a scanned object is provided on a base, and a cover that covers the optical mechanism and blocks light is provided. The object of the present invention is to provide an optical scanning device, characterized in that at least one imaging lens is disposed on the inner surface of the cover so as to be close to the deflection means and to input laser light from the deflection means.

[Function] In the optical scanning device of the present invention, a laser beam is irradiated from a light source,
The laser beam is deflected in a predetermined direction by a deflecting means and scanned, and the deflected laser beam is focused on a scanned object by an imaging lens system.

By arranging at least one imaging lens on the inner surface of the cover so as to input the laser light from the deflection means, the imaging lens and the deflection means can be arranged close to each other. It becomes possible.

[Example] Hereinafter, the overall configuration of an optical scanning device embodying the present invention will be explained as follows.
This will be explained with reference to the figures.

As shown in the figure, the optical scanning device of this embodiment scans a photoreceptor drum 2 using laser light, and has a rotating polygon mirror device 5. Imaging lens (fθ lens) 7° reflection mirror 9. Optical components such as the second cylindrical lens 11 are provided, and a cover 13 is attached to cover these optical components.

The optical bench 3 is made of unsaturated polyester filled with glass fiber and heated and compressed, and the optical bench 3 has a storage hole [5] for storing a rotating polygon mirror device 5 and a second cylindrical lens]]. [fixing member for fixing] 6, and the second
A rectangular opening that serves as a path for the laser beam to the cylindrical force reflex]] and a fixing hole 1 for fixing the cover 13.
8 and a screw hole 19 are formed.

The rotating polygon mirror device 5 includes a laser diode 20 (FIG. 3)
A rotating polygon mirror 22 that deflects and reflects the laser beam irradiated from the mirror, a motor 23 that rotates the rotating polygon mirror 22, and a motor flange that extends above the optical bench 3 to fix this device 5 to the optical bench 3. It consists of a section 24.

The fθ lens 7, as shown in FIG. , the cover 1 is placed close to the rotating polygon mirror 22.
It is attached on the 3rd side.

h- That is, on the inside of the upper part of the cover 13, lens supports 25a to 25d constituting the lens support section 25 protrude downward so as to surround the fθ lens 7 on all sides. 25C225d, the other pair of lens supports 25 should be set at a height that does not block the optical path of the laser beam.
a, 25b are leaf springs 27 extending inward at their tips.
a and 2-7b are screwed.

In the x direction of the arrow (Fig. 1), the fθ lens 7
The optical axis side of the fθ lens 7 is brought into contact with the inner surfaces of the lens supports 25c and 25d for positioning, and the outer peripheral portion of the FE lens 7 is brought into contact with the inner surfaces of the lens supports 25a and 25b in the direction of arrow Y. Furthermore, in the direction of arrow Z, the outer peripheral portion of the fθ lens 7 comes into contact with the support surface 13a that is integrally formed with the cover 13, and the positioning tongue leaf spring 27a is brought into contact with the support surface 13a.

It is pressed and fixed by 27b.

In addition, the reflecting mirror 9 is configured as shown in FIG.
It is a rectangular mirror that reflects the laser beam from the θ lens 7 toward the photoreceptor drum 2 side, and the side surface 13b is inclined at a predetermined angle, that is, the mirror is inclined in advance at an angle that allows such reflection. Cover 13 molded by
It is attached to the side surface 13b of.

The second cylindrical lens]] is arranged in line with the opening [7] to guide the laser beam from the reflection mirror 9 to the photosensitive drum 2, and is a rectangular lens that can be slid in its longitudinal direction. be.

The cover 13 that covers the above-mentioned optical component is a light-shielding cover made of thermoplastic resin containing glass fiber, and is equipped with the lens support part 25 on the inside upper part thereof.
The reflective mirror 9 is attached to the inclined side surface 13b. The positioning plate is fixed to the optical bench 3 by means of a fixing protrusion 26 that engages with the fixing hole 18 and a screw 30 passed through the screw hole 19.28.

Next, the operation of the optical scanning device according to the present embodiment having the above configuration will be explained based on FIG. 3.

First, an LED driver (not shown) is activated by an image information signal.
The laser light emitted from the laser diode 20 as a light source is converted into a parallel beam by the collimator lens 32.The laser light is then turned into a parallel light beam by the collimator lens 32.The laser light is then passed through the first cylindrical lens 33 to the mirror surface of the rotating polygon mirror 22 that rotates at a constant high speed. 2
2a.

As the rotating polygon mirror 22 rotates, the reflected laser beam is deflected within a predetermined angle range for each mirror surface 22a. Therefore, as the rotating polygon mirror 22 rotates at a constant speed, the laser beam Scan the same angular range repeatedly.

The laser beam reflected by the rotating polygon mirror 22 passes through the fθ lens 7 as an imaging lens so as to form an image in a straight line at a constant speed on the circumferential surface of the photoreceptor drum 2 as an object to be scanned. do. Next, the reflection mirror 9 reflects the light in a direction perpendicular to the direction of incidence, and the light reaches the second cylindrical lens 11 .

Laser light enters the surface of the photoreceptor drum 2 from the second cylindrical lens 1 to perform main scanning.At the same time, the rotation of the photoreceptor drum 2 performs sub-scanning.

=8- The synchronization signal that determines the writing start position of this main scan is made by reflecting the laser beam at a predetermined position before the start of writing in the deflection range that has passed through the lens 7 on the Doyo mirror 35 after synchronization, and detecting the synchronization. The light is made incident on the optical sensor 36, which is a photoelectric element, and its detection output is obtained.

As described above, the optical scanning device of this embodiment is equipped with a cover 13.
A thousand lenses 7 are attached to the inside of the upper part by the lens support part 25.
is installed. This allows the fθ lens 7 to be placed very close to the rotating polygon mirror 22 so as to receive the laser beam reflected by the mirror surface 22a without being obstructed by the motor flange portion 24. Therefore,
The entire device can be formed compactly, and a sufficient scanning angle can be obtained even when using the inexpensive 1000 lens 7 with a small aperture, so a significant cost reduction can be achieved.

In addition, since the lens supports 25a-d and plate springs 27a and 27b arranged in a rectangular shape are used to fix the fθ lens 7, it is possible to use a partially cut half-moon shaped lens. , the fθ lens 7 can be easily attached, and the accuracy of the attachment is improved. In addition, unlike conventional methods, there is no need to process the f-theta lens 7 into a strip by removing the part other than the part scanned by the laser beam, so there is no need to increase the processing accuracy of one side to be cut, reducing processing costs. There are advantages.

Furthermore, since the reflection mirror 9 is directly fixed to the cover 13, a highly accurate optical scanning device 1 can be obtained without assembly adjustment such as the reflection angle of the laser beam.

In addition, by fixing the cover 13 to the optical bench 3 using the positioning member 26 and screw holes 19.28, dust and toner can enter the optical scanning device and adhere to the surfaces of lenses and mirrors, causing contamination. It can effectively prevent unnecessary light from entering from the outside.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, by providing the imaging lens on the cover that covers the optical component, the imaging lens can be brought closer to the rotating polygon mirror.

As a result, a sufficient scanning angle can be obtained with a small-diameter imaging lens, so the entire optical scanning device can be made smaller, and the number of manufacturing steps does not increase, making it possible to manufacture an inexpensive and highly accurate optical scanning device. I can do it.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the broken structure of the optical scanning device of the embodiment, FIG. 2(A) is a front view showing the fixed state of the fθ lens,
FIG. 2(B) is a bottom view thereof, FIG. 3 is an explanatory diagram showing the optical path of a laser beam, and FIG. 4 is a partially cutaway front view of a conventional example. ] ... Optical scanning device 3 ... Optical bench 7 ... fθ lens 22 ... Rotating polygon mirror 24 ... Motor flange section 25 ... Lens support section

Claims (1)

[Scope of Claims] 1. A light source that irradiates a laser beam, a deflection device that deflects the laser beam in a predetermined direction and scans it, and an image that focuses the laser beam deflected by the deflection device on a scanned object. In an optical scanning device, in which an optical mechanism including a lens system is provided on a base, and a cover is provided to cover the optical mechanism and block light, at least one imaging lens is disposed close to the deflecting means. An optical scanning device characterized in that the optical scanning device is arranged on an inner surface of the cover so as to input the laser beam from the deflecting means.