JPH0318811A - Optical deflecting device - Google Patents

Abstract

PURPOSE:To eliminate the eccentricity of a rotary polygon mirror, to eliminate the deviation of a write image, and to improve the recording quality by placing a pressing plate through which a rotary shaft passes without a clearance between an elastic member and the rotary polygon mirror. CONSTITUTION:A pressing plate 46 through which a rotary shaft 43 passes without a clearance is placed between an elastic member 47 and a rotary polygon mirror 33. Also, at the time of fixing the rotary polygon mirror 33, force in the diameter direction generated by a fact that the elastic member 47 is crushed is obstructed by the pressing plate 46 so that its force is not transmitted to the rotary polygon mirror 33. In such a way, the eccentricity of the rotary polygon mirror 33 is eliminated, the deviation of a write image is eliminated, and the recording quality can be improved.

Description

[Detailed Description of the Invention] This invention provides a printer, facsimile, and printer using a laser.
The present invention can be used in an electrophotographic recording device that records on paper using an electrophotographic process, such as a copying machine. Specifically, the writing system in such an electrophotographic recording device,
The present invention relates to an optical deflection device that deflects and scans a photoreceptor.

! Conventionally, in this type of optical deflection device, as shown in FIG. 7, for example, a positioning surface 2a is formed on the rotor 2 of the motor 1, and an elastic member such as a wave washer or an O-ring is attached to the positioning surface 2a. 3 to rotate the polygon fi in the direction of the arrow in the figure.
4, the rotating polygon mirror 4 is rotated together with the rotor 2 around the rotating shaft 5, and each mirror surface 4a on the outer periphery is rotated.
The light from a light source (not shown) is sequentially reflected and deflected and scanned over a photoreceptor (not shown).

By the way, in such a light deflection device, the surface angle of the positioning surface 2a with respect to the one-rotation axis 5 is set accurately so that the mirror surface 4a is not tilted, and the rotating polygon mirror 4 is attached to the positioning surface 2a.
A slight clearance C was provided between the center hole 4b of the rotating polygon mirror 4 and the outer periphery of the shaft portion 2b of the rotor 2 in order to ensure close contact and accurate positioning.

However, in this type of conventional optical deflection device, the rotating polygon mirror 4 is positioned by accurately achieving coaxiality with the rotating shaft 5, and the elastic member 3 and the plate 6 are sandwiched between the rotating polygon mirrors 4 and 5. When the ring 7 is installed and fixed, as the elastic member 3 is crushed, a radial force is applied to the rotating polygon mirror 4, and the rotating polygon! 4 may be moved in the radial direction within the range of the clearance C and become eccentric with respect to the rotating shaft 5. Then, as shown in FIG. 8, for example, as the rotating polygon mirror 4 rotates, the position of each mirror surface 4a shifts by a minute distance Ω in the range from a to b. Light a from light g7 is reflected at position a as shown by the solid line in the figure, and reflected at position b as shown by the chain line in the figure, resulting in images being formed at positions shifted by a micro ratio of 11 m. This causes a problem in that the written image on the photoreceptor 8 is shifted between the mirror surfaces 48, resulting in a significant deterioration in recording quality.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such conventional problems in optical deflection devices, eliminate eccentricity of a rotating polygon mirror, eliminate displacement of written images, and improve recording quality.

For this purpose, the present invention according to claim 1 has a rotating shaft 4, as shown in the embodiment shown in FIGS. 1 and 2 below, for example.
A rotor 44 rotating about 3 has a positioning surface 44a perpendicular to its rotation axis 43, and the positioning surface 44a is perpendicular to its rotation axis 43.
The rotating polygon mirror 33 is rotated together with the rotor 44 to reflect the light from the light source 30, and the light is deflected and scanned on the photoreceptor 11. The deflection device is characterized in that a holding plate 46 is sandwiched between the elastic member 47 and the rotating polygon mirror 33, through which the rotating shaft 43 passes through without any clearance.

Further, the invention according to claim 2 is as shown in the embodiment shown in FIGS. 3 and 4 below, for example.

A positioning surface 44a perpendicular to the rotation axis 43 is formed on a rotor 44 rotating around a rotation shaft 43, and a rotating polygon mirror 33 is pressed against the positioning surface 44a by an elastic member 52. 33 rotates together with the rotor 44 to reflect the light from the light source 30 and direct the photoreceptor 1
In the optical deflection device that deflects and scans the surface of the rotating polygon, the elastic member 52 is provided with a holding plate portion 52b through which the rotating shaft 43 passes through without clearance, and extending from the holding plate portion 52b through the holding plate portion 52b. The mirror 33 is characterized by being provided with an elastic portion 52c that presses the mirror 33 against the positioning surface 44a.

Function When fixing the rotating polygon @33, the elastic member 47
The force in the radial direction caused by being crushed is blocked by the holding plate 46 to prevent the force from being transmitted to the rotating polygon mirror 33.

Further, the force in the radial direction generated when the elastic portion 52c is compressed is transferred to the rotating polygon mirror 3 by the pressing plate portion 52b.
Make sure it doesn't get passed on to 3.

χ-1-■ Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 6 shows a schematic overall configuration of the internal mechanism of a laser printer equipped with an optical deflection device according to an embodiment of the present invention, as viewed from the front side. The reference numeral 10 in the figure is the main body of the apparatus.

Inside the apparatus main body 10, a drum-shaped photoreceptor 11 is provided at the center. A charger 12, a developing device 13, a transfer/separation charger 14, and a cleaning device 15 are arranged around the photoreceptor 11 in the rotational direction (counterclockwise in the drawing). A laser writing system 16 is provided below the developing device 13. On the other hand, two paper feed cassettes 18 for storing paper 17 are attached to the right side of the apparatus main body 10 in the figure. At the attachment part of each paper feed cassette 18,
Paper feeding units 20 each having a paper feeding roller 19 are provided. A pair of registration rollers 22 are arranged on the developing device 13 and communicate with the paper feeding section 20 via a paper feeding path 21 . On the other hand, on the opposite side of the transfer/separation charger 14 from the registration roller pair 22, there is a conveyor 23 and a fixing device 2.
4 are arranged in order. A pair of paper ejection rollers 25 is provided on the left side of the fixing device 24 in the figure, and a paper ejection receiver 26 is further provided on the left side thereof, protruding from the main body 10 of the apparatus.

Therefore, when forming an image using this laser printer, the paper feed roller 19 is driven to send out the paper 17 from the paper feed cassette 1B in the six directions indicated by the arrows in the figure.
It passes through the paper feed path 21 and abuts its leading end against a pair of registration rollers 22 . On the other hand, while rotating counterclockwise in the figure, the surface of the photoreceptor 11 is first uniformly charged with a charger 12, and then a laser beam is irradiated with a laser writing system 16 to form an electrostatic latent image on the surface. is formed, and then the developing device 13
The electrostatic latent image is sequentially visualized using toner. Then, in synchronization with the image, the above-mentioned paper 17, which had been in contact with the pair of registration rollers 22, is guided onto the photoreceptor 11. When the paper passes over the photoreceptor 11, the transfer/separation charger 14 transfers the image formed on the surface of the photoreceptor 11 to the lower surface of the paper 17 and records the paper. 17 is electrostatically separated.

Then, the surface of the photoreceptor 11 is cleaned by a cleaning device 15 to remove residual toner on the photoreceptor 11. on the other hand,
The paper 17 is sent to the fixing device 24 by the conveyor 23,
The transferred image is fixed by the fixing device 24. Thereafter, the sheets 17 are sent out in the direction of arrow B in the figure by a pair of paper discharge rollers 25, and the sheets 17 on which recording has been completed are stacked one after another on a paper discharge tray 26.

By the way, the above-mentioned laser writing system 16 is basically constructed as shown in FIGS. 5(A) and 5(B). That is, the neutral number 3o in FIG. 1 is a laser light source such as a semiconductor laser, and the laser light source 30 emits laser light. The laser beam is converted into a parallel beam by a collimating lens 31, and is then passed through an imaging lens 32 to enter the optical deflection device according to the present invention.

The optical deflection device rotates a rotating polygon mirror 33 and reflects the laser beam on its mirror surface 33a, and directs the laser beam to the cylindrical lens 3.
Turn to 4. And that cylindrical lens 34
The photoreceptor 11 is deflected and scanned.

Now, as shown in FIG. 1, the optical deflection device according to the present invention includes a motor 41 inside a motor case 40. As shown in FIG. That is, a ball bearing 42 is provided at the center of the motor case 40,
The rotary shaft 43 is vertically supported by the ball bearing 42 so as to be rotatable. The rotary shaft 43 has a rotor 44 of the motor 41.
Attach.

A magnet 45 is attached to the lower surface of the rotor 44, and a positioning surface 44a perpendicular to the rotating shaft 43 is formed on the upper surface. Further, a shaft portion 44b is provided at the center of the upper surface. Then, the shaft portion 44b is fitted with the center hole 33a with a slight clearance as in the conventional case, and the positioning surface 44a is fitted.
The above-mentioned rotating polygon mirror 33 is placed on top. Rotating polygon mirror 33
A press plate 46 shown in FIG. 2(A) is placed on top. One rotation 043 passes through the center hole 46a of the holding plate 46 without any clearance. On the holding plate 46, there is an elastic member 47 such as a wave washer or a ring as shown in FIG. 2(B).
put on. Further, on the elastic member 47, there is shown in FIG.
Place the board 48 shown in C). Similarly, the rotating shaft 43 passes through the center hole 48a of the plate 48 without any clearance. Then, a ring 49 placed above the plate 48 is fitted onto the rotating shaft 43, and the elastic member 47 is applied to force the rotating polygon mirror 33 against the positioning surface 44a. On the other hand, the magnet 45 attached to the rotor 44 faces the coil 5o attached to the motor case 40. Then, the coil 50 is energized to rotate the rotor 44, and the rotary polygon mirror 33 is rotated together with the rotor 44.

Also in this optical deflection device, since a slight clearance is provided between the shaft portion 44b of the rotor 44 and the center hole 33a of the rotating polygon mirror 33, the rotating polygon fi 33 moves during assembly, causing eccentricity with respect to the rotating shaft 43. It is also possible to do so. However, in this embodiment, since the holding plate 46 is sandwiched between the rotating polygon mirror 33 and the elastic member 47, when the rotating polygon mirror 33 is fixed, the force in the radial direction caused by the elastic member 47 being crushed is absorbed. It is blocked by the holding plate 46 to prevent the force from being transmitted to the rotating polygon jl' 133.

In the embodiment shown in FIG.
4a, the rotating polygon fi 33 is pressed against the positioning surface 44a by the elastic member 52, and the rotating polygon fi 33 is rotated together with the rotor 44, and the mirror 33a is rotated together with the rotor 44.
As shown in FIG. 4, the elastic member 52 that reflects the light from the light source 30 and deflects it to scan the photoreceptor 11 has a holding plate portion 52b having a center hole 52a through which the rotating shaft 43 passes without clearance. and an elastic part 52c extending from the holding plate part 52b and pressing the rotating polygon @33 against the positioning surface 44a via the holding plate part 52b.

In this embodiment, since the holding plate portion 52b prevents the elastic member 52 from moving in the radial direction, when the rotating polygon mirror 33 is fixed, the radial force generated by the elastic portion 52c being crushed is applied to the rotating polygon mirror 33. This will not be communicated to the 33rd.

Therefore, according to the present invention, the force generated when the elastic member is crushed by the presser plate is prevented from being transmitted to the rotating polygon mirror, or the force generated when the elastic member is crushed by the presser plate is prevented from being transmitted to the rotating polygon mirror. It is possible to prevent force from being transmitted to the rotating polygon mirror, eliminate the eccentricity of the rotating polygon mirror, eliminate deviation of written images, and improve recording quality.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an optical deflection device which is an embodiment of the present invention as set forth in claim 1, and FIG. 2 (A) and (B)
(C) is a perspective view of a holding plate, a wave washer, and a plate used in the optical deflection device, and FIG. 4 is a perspective view of an elastic member used in the optical deflection device, and FIG. 5 is an explanation of the principle of a laser writing system equipped with the optical deflection device according to the present invention, where (A) is a front view and (B)
6 is a plan view, and FIG. 6 is an overall schematic diagram of the internal mechanism of the laser printer equipped with the laser writing system. FIG. 7 is a sectional view of a conventional optical deflection device, and FIG. 8 is an explanatory diagram illustrating the occurrence of deviation in written images in the conventional optical deflection device. 11......Photoreceptor, 30......
・Light source, 33...Rotating polygon mirror, 43...
...Rotating axis, 44...Rotor, 44a...Positioning surface, 46...
・・・・・・Press plate, 47・・・・・・Elastic member,
52......Elastic member, 52b...
... Pressing plate part, 52c... Elastic part.

Claims (1)

[Claims] 1. A positioning surface perpendicular to the rotation axis is formed on a rotor that rotates around the rotation axis, and a rotating polygon mirror is pressed against the positioning surface by urging it with an elastic member. In an optical deflection device that rotates a mirror together with the rotor to reflect light from a light source and deflect and scan it on a photoreceptor, the rotation shaft passes through the elastic member and the rotating polygon mirror without any clearance. A light deflection device consisting of a presser plate. 2. A positioning surface perpendicular to the rotation axis is formed on the rotor rotating around the rotation axis, a rotating polygon mirror is pressed against the positioning surface by biasing with an elastic member, and the rotating polygon mirror is rotated together with the rotor. In an optical deflection device that reflects light from a light source and deflects and scans it on a photoreceptor, the elastic member includes a holding plate portion through which the rotating shaft passes through without clearance, and a holding plate extending from the holding plate portion. and an elastic part that presses the rotating polygon mirror against the positioning surface via the elastic part.