JPS61175613A - Optical polarizing device of rotary polygon mirror - Google Patents

Abstract

PURPOSE:To facilitate the size control of an elastic member fitting part and to also facilitate its assembly by providing a receiving member with a cylindrical projection part, piercing a hole in a rotary polygon mirror wherein a projection part is fitted, and providing the projection part with a lock part which prevents an elastic member from moving axially. CONSTITUTION:The rotary polygon mirror 2a of the receiving member 12 fixed on a motor rotating shaft 1 is provided with a cylindrical projection part 2b which surrounds the shaft 1 and projects axially. The circular hole in which the cylindrical projection part 2b is fitted is pierced in the center of the rotary polygon mirror 3 and the projection part 2b is fitted therein to bring a reference fitting surface 3a into contact with the receiving surface 2a of the receiving member 2. An annular groove 2c is formed in the cylindrical projection part 2b so that its upper flank is slightly above the top surface of the rotary polygon mirror 3. The elastic member 10 is mounted in the annular groove 2c and the elastic member 10 is constituted by forming integrally a snap ring type annular part 10a which is cut at one position and tongue pieces 10b of elastic material projecting radially slightly downward from its outer peripheral surface.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical deflection device for a laser printer or the like that uses a rotating polygon mirror to deflect a laser beam within a predetermined angular range to perform writing and scanning.

Conventionally, in portable laser printers and the like, a rotating polygon mirror has been widely used as an optical deflection device for scanning a photoreceptor surface by deflecting a laser beam modulated by one image signal over a predetermined angular range to perform optical writing.

In an optical deflection device using a rotating polygon mirror, when attaching a single rotation polygon mirror to a rotating shaft, the screws etc. that fix the rotating polygon mirror to the mounting member provided on the shaft must be tightened too tightly. When the mirror surface is distorted, the surface of the mirror is tilted, causing pitch unevenness in the image. To prevent this.

As a method of attaching a rotating polygon mirror to a rotating shaft, the mounting reference surface of the rotating polygon mirror is brought into contact with the receiving surface perpendicular to the rotating shaft of a receiving member fixed to the rotating shaft, and the Press the side surface with an elastic member with a moderate pressure 1
A method has been adopted in which a rotating polygon mirror is fixed to a receiving member.

In the optical deflection device having the above structure, the elastic member for pressing the rotating polygon mirror against the mounting member has conventionally been a receiving member 2 fixed to the rotating shaft 1 by press fitting or adhesive, as shown in FIG. 7, for example. , the rotating polygon mirror 3 is mounted on the receiving surface 2a perpendicular to the axis so that the reference surface 3a is in contact with the rotating polygon mirror 3.
A method is to fit the hole in the center of the bushing nut onto the shaft 1, place it there, push the bushing nut onto the shaft 1 from above, and press the surface 3b of the rotary polygon mirror 3 on the opposite side of the reference surface with the lower surface around the bushing nut. Are known. Bushnut 4 is shown in Fig. 8(a), (
As shown in b), a notch 4a is provided outward from the periphery of the hole in a disc made of an elastic material with a hole smaller than the outer diameter of the shaft 1. When this is pushed in from the upper end of the shaft 1 as shown in FIG. Disk outer peripheral portion 4 that slides and forms a planar shape
c is pushed in until it abuts against the upper surface 3b of the rotating polygon mirror with a required pressing force. Due to the elasticity of the tongue piece 4b, the inner peripheral edge of the bushnut 4 presses against the outer peripheral surface of the shaft 1 and is fixed by frictional force, and the pressing force between the bushnut and the upper surface -3b of the rotating polygon mirror is also caused by the elasticity of the tongue piece 4b of the bushnut. It is obtained by

Further, as shown in FIG. 9, an annular groove 1a is provided at a certain distance from the upper surface 3b of the rotating polygon mirror 3 on the rotating shaft 1, and a locking member 5 such as an E-ring is fitted into the ring groove 1a. A mounting method is also known in which a compression spring 7 is provided between the polygon mirror 3 and a retaining ring 6 placed on the polygon mirror upper surface 3b, and the rotating polygon mirror 3 is pressed against and fixed to the receiving member 2.

However, in the case of the former bush nut method, there is no axial positioning or removal stop, so it is difficult to control the dimensions of the bush nut's locking position, and the insertion pressure increases due to variations in the bush nut's inner diameter and shaft outer diameter. The pressing force of the rotating polygon mirror tends to vary, and when the pressing force is too large, the rotating polygon mirror becomes distorted and the surface tilts, and when the pressing force is small, slipping occurs between the rotating polygon mirror and the receiving member. occurs.

In addition, in the case of the latter fixing method using a member such as an E-ring that is locked to the shaft and a compression spring, it is easy to control the dimensions of the spring mounting position, but the number of parts increases, so it takes time to assemble. However, it has the disadvantage of high cost.

Furthermore, since the annular groove that determines the positions of both ends of the spring and the receiving member that receives the rotating polygon mirror are separate members, there is a drawback that dimensional control during assembly becomes difficult.

In either case, a hole is drilled in the center of the rotating polygon mirror,
The diameter of the hole that fits onto the motor's rotating shaft to position the center of rotation must match the outer diameter of the motor's shaft, so many single-turn polygon mirrors have to be small in diameter. When a large number of workpieces are passed through and supported by a holding shaft for simultaneous machining, the rigidity of the holding shaft decreases, and the holding shaft is easily deformed by machining force, causing chatter and reducing machining accuracy. There are drawbacks.

The present invention has a simple structure that eliminates the above-mentioned drawbacks of the optical deflection device using the conventional rotating polygon mirror fixing method, and the dimensions of the elastic member mounting portion can be easily controlled and assembly is easy. It is an object of the present invention to provide a rotating polygon mirror light deflecting device that can be held by a highly rigid holding shaft when processing a large number of rotating polygon mirrors simultaneously.

In order to achieve the above-mentioned object, the present invention provides a cylindrical protrusion concentrically with the motor rotation axis, surrounding the rotation axis, and protruding in the axial direction toward the rotating polygon mirror on the receiving member. The present invention is characterized in that a hole is bored into which the protrusion fits, and a locking part is provided in the protrusion to prevent the end of the elastic member opposite to the rotating polygon mirror pressing side from moving in the axial direction.

The present invention will be explained below based on embodiments shown in the drawings.

In the embodiment shown in FIG. 1, a rotating polygon mirror 2a of a receiving member 2 fixed to a motor rotation shaft 1 is provided with a cylindrical protrusion 2b that surrounds the shaft 1 and projects in the axial direction. A circular hole is provided at the center of the polygon mirror 3 to fit into the cylindrical protrusion 2b, and this is fitted into the protrusion 2b to abut the mounting reference surface 3a against the receiving surface 2a of the receiving member 2. 0
An annular groove 2c is provided in the cylindrical protrusion 2b so that the upper surface thereof is located slightly above the upper surface of the single-rotation polygon mirror 3.

An elastic member 10 shown in FIGS. 2(a) and 2(b) is attached to the annular groove 2c. The elastic member 10 is integrally formed of an elastic material with a snap ring-shaped annular portion 10a cut at one point and a tongue piece 10b projecting radially outward and downward from the outer peripheral surface of the annular portion 10a. It is composed of The cut portion is opened so that the inner diameter of the annular portion 10a is larger than the outer diameter of the cylindrical projection 2b of the receiving member, and the annular portion 10a is inserted from the upper end and restored to its original state at a position that coincides with the annular groove 2c. In this state, the tip of the tongue piece 10b of the elastic member elastically presses the upper surface of the rotating polygon mirror 3 due to its own elasticity, and due to the reaction force, the upper surface of the annular portion 10a is moved to the upper surface of the annular groove 2c. It is positioned in the axial direction by abutting on.

As described above, in the optical deflection device of this embodiment, the receiving surface 2a that receives the reference surface of the one-rotation polygon mirror 3 and the upper surface of the annular groove 2c that positions the upper end of the elastic member 10 are formed on the same receiving member 2. Therefore, the mounting dimensions of the elastic member 10 can be easily controlled simply by improving the machining accuracy of the receiving member 2, and the rotating polygon mirror is always suppressed and fixed to the receiving surface with a constant pressing force. This makes it possible to prevent the mirror surface from tilting due to excessive pressing force and from slipping due to insufficient pressing force.

In addition, the diameter of the hole that positions the center of rotation of the single-rotation polygon mirror 3 can be made to the required size regardless of the outer diameter of the motor's rotating shaft, so when machining multiple pieces at the same time, sufficient rigidity can be maintained. It can be held on the thick shaft provided with the machine, improving machining accuracy.

As the elastic member for pressing the rotating polygon mirror 3 against the receiving member 2, in addition to the one shown in FIG. 2, the one shown in FIG.

It is also possible to use the corrugated washer 20 shown in (b) whose inner diameter can be enlarged by cutting one part, or the snap ring 30 with a warp as shown in FIG. 4. 5 and 6 show these elastic members 20.
30 is a cross-sectional view showing a state in which the rotating polygon mirror 3 is pressed and fixed to the receiving member 2 using the rotating polygon mirror 3.

庺-21 As described above, according to the present invention, with a simple configuration, it is possible to easily manage the dimensions of the attachment part of the elastic member that presses against the receiving member of the single-rotation polygon mirror, and to prevent the mirror surface from tilting and slipping. Furthermore, it is possible to improve the accuracy of simultaneous processing of a large number of single-rotation polygon mirrors.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2(a),
(b) is a plan view and a cross-sectional view of an example of the elastic member used in the example, FIGS. 3(a), (b), and 4.
Figures (a) and (b) are plan views and cross-sectional views of other examples of elastic members used in the present invention, and Figures 5 and 6 show the use of the elastic members shown in Figures 3 and 4, respectively. FIG. 7 is a sectional view of a conventional optical deflection device, and FIG. 8(a) is a sectional view showing the configuration of a rotating polygon mirror mounting portion of a conventional optical deflection device. (b) is a cross-sectional view and a plan view of an elastic member used therein, and FIG. 9 is a cross-sectional view showing the structure of another conventional rotating polygon mirror mounting section. 1...Rotating shaft 2...Receiving member 2a...
Receiving surface 2b... Cylindrical protrusion 2c... Annular groove

Claims (1)

[Claims] The mounting reference surface of the rotating polygon mirror is brought into contact with the receiving surface perpendicular to the rotation axis of the receiving member fixed to the rotating shaft, and the surface of the rotating polygon mirror on the opposite side of the mounting reference surface is elastically moved by an elastic member. In an optical deflection device that is pressed and fixed to a rotating polygon mirror receiving member, the receiving member has a cylindrical protrusion concentrically surrounding the rotating shaft and protruding in the axial direction toward the rotating polygon mirror. A hole is bored in the center of the rotating polygon mirror to fit into the protrusion, and the protrusion is provided with a hole that prevents the end of the elastic member opposite to the pressing side of the rotating polygon mirror from moving in the axial direction. An optical deflection device comprising a locking portion.