JP7114410B2 - Optical scanning device and image forming device - Google Patents

Description

The present invention relates to an optical scanning device and an image forming apparatus, and more particularly to an optical scanning device used in image forming apparatuses such as copiers, printers, and multi-function peripherals.

2. Description of the Related Art It is well known that an optical scanning device used in an electrophotographic image forming apparatus has the following configuration. That is, the optical scanning device deflects a light beam emitted from a light source by a light deflecting means, forms a light spot on the surface to be scanned with the deflected light beam by a scanning imaging optical system, and scans with the light spot. The surface is scanned to form an electrostatic latent image on the scanned surface. A deflector, such as a rotating polygonal mirror, for deflecting the laser light guided from the semiconductor laser is provided inside the optical scanning device. A desired electrostatic latent image is formed on the photosensitive drum by scanning the photosensitive drum with the deflected laser beam and by emitting and extinguishing the semiconductor laser in accordance with the operation of the photosensitive drum. ing.

A rotating member is provided in the deflector, and vibration is generated when the rotating member rotates. This vibration propagates to the semiconductor laser and may cause the semiconductor laser to vibrate. If the semiconductor laser vibrates more than a predetermined amount, the electrostatic latent image formed on the photosensitive drum is defective. Therefore, for example, in Japanese Patent Laid-Open No. 2002-100002, even if there is a poor assembly condition or an uneven load, a light source holding section, which contains a light source, can always be properly positioned. An image forming apparatus has been proposed that suppresses the occurrence of abnormal images.

JP-A-2003-66357

However, in the optical scanning device, when forming an image, the motor unit is driven to drive the rotating polygon mirror of the deflector. Vibration propagates. When this vibration propagates to the semiconductor laser, which is the light source, the optical axis of the laser light emitted from the semiconductor laser may periodically fluctuate in the sub-scanning direction. There is a problem that arises.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent a light source holder holding a semiconductor laser from vibrating in the sub-scanning direction.

In order to solve the above problems, the present invention has the following configuration.

(1) An optical scanning device having a supporting member for supporting a light source holder mounted with a laser chip that emits a laser beam, wherein the light source holder has a cylindrical shape and is provided at one end to which the laser chip is mounted. and a second cylindrical portion provided on the other end side and having a smaller diameter than the first cylindrical portion, and the support member, when supporting the light source holder, a first positioning surface and a second positioning surface that contact the first cylindrical portion; a third positioning surface and a fourth positioning surface that contact the second cylindrical portion ; a pressing member that presses against the first positioning surface, the second positioning surface, the third positioning surface, and the fourth positioning surface, wherein the first positioning surface, the second positioning surface, and the third positioning surface; The surface and the fourth positioning surface are planes formed on the support member, the angle formed by the first positioning surface and the second positioning surface is an acute angle, and the third positioning surface and the fourth positioning surface form an acute angle. The angle formed with the positioning surface is an acute angle, and the first positioning surface and the third positioning surface are planes perpendicular to a sub-scanning direction orthogonal to a main scanning direction in which the laser beam scans the surface to be scanned. An optical scanning device characterized by:
(2) An image forming apparatus for forming an image on a recording medium, comprising the optical scanning device according to (1).

According to the present invention, it is possible to prevent the light source holder holding the semiconductor laser from vibrating in the sub-scanning direction.

Schematic cross-sectional view showing the configuration of an image forming apparatus according to an embodiment 1 is a schematic perspective view showing the configuration of an optical scanning device according to an embodiment; FIG. Perspective view for explaining the configuration of the incident part holder and the light source holder Diagram explaining the force applied to the incident part holder

BEST MODE FOR CARRYING OUT THE INVENTION Below, embodiments of the present invention will be described in detail with reference to the drawings.

In the following description, the rotation axis direction of the rotating polygon mirror 42 of the deflector 43 described later is the Z-axis direction, the main scanning direction that is the scanning direction of the light beam or the longitudinal direction of the optical member is the Y-axis direction, the Y-axis and the Z-axis. The direction orthogonal to is defined as the X-axis direction. Note that the optical axis direction of the optical member is a direction substantially parallel to the X-axis. The Z-axis direction is also the sub-scanning direction, which is the rotation direction of a photosensitive drum, which will be described later.

[Configuration of Image Forming Apparatus]
A configuration of an image forming apparatus according to an embodiment will be described. FIG. 1 is a schematic configuration diagram showing the overall configuration of a tandem-type color laser beam printer according to this embodiment. This laser beam printer (hereinafter simply referred to as a printer) has four image forming engines 10Y and 10M that form toner images for each of the colors yellow (Y), magenta (M), cyan (C) and black (Bk). , 10C, 10Bk (illustrated by dashed lines). The printer also includes an intermediate transfer belt 20 onto which toner images are transferred from image forming engines 10Y, 10M, 10C, and 10Bk. The toner images multiple-transferred onto the intermediate transfer belt 20 are transferred onto a recording sheet P, which is a recording medium, to form a full-color image. Hereinafter, the symbols Y, M, C, and Bk representing each color will be omitted unless necessary.

The intermediate transfer belt 20 is formed in an endless shape and is looped around a pair of belt conveying rollers 21 and 22. The intermediate transfer belt 20 rotates in the direction of arrow H so that the toner image formed by the image forming engine 10 is transferred. It is configured. A secondary transfer roller 65 is disposed at a position facing one belt conveying roller 21 with the intermediate transfer belt 20 interposed therebetween. The recording sheet P is inserted between the secondary transfer roller 65 and the intermediate transfer belt 20 which are in pressure contact with each other, and the toner image is transferred from the intermediate transfer belt 20 . Below the intermediate transfer belt 20, the four image forming engines 10Y, 10M, 10C, and 10Bk are arranged in parallel. (hereinafter referred to as primary transfer). These four image forming engines 10 are arranged along the rotational direction of the intermediate transfer belt 20 (direction of arrow H). and the image forming engine 10Bk for black.

Further, below the image forming engines 10, an optical scanning device 40 is arranged for exposing a photosensitive drum 50, which is a photosensitive member provided in each image forming engine 10, according to image information. Note that detailed illustration and description of the optical scanning device 40 are omitted in FIG. 1, and will be described later with reference to FIG. The optical scanning device 40 is shared by all the imaging engines 10Y, 10M, 10C, and 10Bk, and has four semiconductor lasers (not shown) that emit light beams modulated according to image information of each color. The optical scanning device 40 also includes a rotary polygon mirror 42 that rotates at high speed and deflects each light beam so as to scan the light beams of these four optical paths along the rotation axis direction (Y-axis direction) of the photosensitive drum 50, and a rotating polygon mirror 42 that rotates. A deflector 43 comprising a motor unit for rotating the polygon mirror 42 is provided. Each light beam scanned by the deflector 43 travels along a predetermined path while being guided by an optical member installed in the optical scanning device 40 . Then, each light beam that has traveled a predetermined path exposes each photosensitive drum 50 of each image forming engine 10 through each irradiation port (not shown) provided in the upper portion of the optical scanning device 40 .

Each image forming engine 10 also includes a photosensitive drum 50 and a charging roller 12 that charges the photosensitive drum 50 to a uniform background potential. Each image forming engine 10 further includes a developing device 13 that develops an electrostatic latent image formed on the photosensitive drum 50 (photoreceptor) by exposure to light beams to form a toner image. The developing device 13 forms a toner image corresponding to image information of each color on a photosensitive drum 50 which is a photosensitive member.

A primary transfer roller 15 is disposed at a position facing the photosensitive drum 50 of each image forming engine 10 so as to sandwich the intermediate transfer belt 20 . A predetermined transfer voltage is applied to the primary transfer roller 15 to transfer the toner image on the photosensitive drum 50 to the intermediate transfer belt 20 .

On the other hand, the recording sheet P is supplied from the paper feed cassette 2 accommodated in the lower part of the printer housing 1 to the inside of the printer, specifically to the secondary transfer position where the intermediate transfer belt 20 and the secondary transfer roller 65 are in contact. be. A pickup roller 24 and a paper feed roller 25 for pulling out the recording sheets P accommodated in the paper feed cassette 2 are arranged in parallel on the top of the paper feed cassette 2 . Further, a retard roller 26 for preventing multi-feeding of the recording sheets P is arranged at a position facing the paper feed roller 25 . A conveying path 27 for the recording sheet P inside the printer is provided substantially vertically along the right side surface of the printer housing 1 . A recording sheet P pulled out from a paper feed cassette 2 located at the bottom of the printer housing 1 rises along a conveying path 27 and is sent to a registration roller 29 that controls the entry timing of the recording sheet P to the secondary transfer position. be done. Thereafter, after the toner image is transferred to the recording sheet P at the secondary transfer position, the recording sheet P is sent to the fixing device 3 (illustrated by broken lines) provided downstream in the conveying direction. Then, the recording sheet P on which the toner image is fixed by the fixing device 3 is discharged to the discharge tray 1 a provided in the upper part of the printer housing 1 through the discharge roller 28 .

When a full-color image is formed by the color laser beam printer configured as described above, first, the optical scanning device 40 exposes the photosensitive drum 50 of each image forming engine 10 at a predetermined timing according to the image information of each color.

[Configuration of Optical Scanning Device]
FIG. 2 is a perspective view showing the configuration of the optical scanning device 40 of this embodiment. The optical box 101, which is the housing of the optical scanning device 40, has a bottom surface (bottom portion) parallel to the XY plane, and an outer wall (side wall, hereinafter also referred to as an outer peripheral portion) standing from the bottom surface and substantially parallel to the Z-axis direction. ) and An incident part holder 103 mounted with a laser light source (light source) for emitting a light beam is attached to the outer peripheral part (side wall) of the optical box 101 of the optical scanning device 40 . Furthermore, a circuit board 110 for driving the laser emission source is attached to the outside of the entrance holder 103 . Inside the optical scanning device 40, there are provided a rotating polygon mirror 42 for reflecting and deflecting the light beam, an optical lens 60 (60a to 60d) necessary for guiding the light beam onto the photosensitive drum 50 and forming an image, Reflecting mirrors 62 (62a to 62e) and the like are installed. The reflecting mirror 62 is fixed to the optical box 101 by fixing springs at both ends in the longitudinal direction (Y-axis direction). The light beams deflected by the rotary polygon mirror 42 pass through optical lenses 60a and 60c having strong power in the main scanning direction (Y-axis direction), and then pass through the optical lens 60b having strong power in the sub-scanning direction (X-axis direction). , 60d. The light beam that has passed through the optical lens 60 is reflected at least once by the reflecting mirror 62, guided to the photosensitive drum 50, and imaged.

[Construction of incident part holder]
FIG. 3 is a diagram for explaining the light source holder 111 that holds the laser chip 112 that is the light source, and the incident part holder 103 that is the supporting member that supports the light source holder. FIG. 3A is a perspective view showing a state in which the light source holders 111a and 111b are attached to the entrance holder 103 and the light source pressing member 113 presses and supports the light source holders 111a and 111b. Laser chips 112a and 112b are attached to the light source holder 111 and held by the light source holders 111a and 111b. The light source pressing member 113 is made of a plate spring and is screwed to the entrance holder 103 . Light source holders 111a and 111b holding laser chips 112a and 112b are attached to the entrance holder 103 . Each of the light source holders 111a and 111b is pressed against the contact surface with the incident portion holder 103 by pressing portions 113a and 113b (see FIG. 4A) of the light source pressing member 113 (not shown in FIG. 3A). Thus, it is supported by the entrance holder 103 . Also, the entrance holder 103 is screwed to the side wall of the optical box 101 of the optical scanning device 40 .

FIG. 3(b) is a perspective view showing the shape of the entrance holder 103 with the light source holders 111a and 111b and the light source pressing member 113 removed from the state shown in FIG. 3(a). sub-scanning direction. In order to fix the light source holder 111 at a desired position of the incident portion holder 103, the incident portion holder 103 is provided with a positioning surface with which the light source holder 111 abuts when the light source holder 111 is attached to the incident portion holder 103. ing. FIG. 3B shows four positioning surfaces 115a, 115b, 115c, and 115d with which the light source holder 111a abuts when the light source holder 111a shown in FIG. and each positioning surface is composed of a plane. The positioning surfaces 115b and 115d are surfaces perpendicular to the sub-scanning direction. Furthermore, the positioning surfaces 115a and 115c are parallel, and the positioning surfaces 115b and 115d are also parallel. Further, the angle at which the two positioning surfaces intersect when the positioning surfaces 115a and 115b are respectively extended constitutes an acute angle, which is 60 degrees in this embodiment. Similarly, when the positioning surfaces 115c and 115d are respectively extended, the angle at which the two positioning surfaces intersect constitutes an acute angle, which is 60 degrees in this embodiment. In addition, although FIG. 3B shows a positioning surface for the light source holder 111a, the entrance holder 103 is also formed with a similar positioning surface for the light source holder 111b, as will be described later. . In addition, the incident portion holder 103 has adhesive fixing portions 116 for fixing the light source holders 111a and 111b to the incident portion holder 103 with an adhesive. The recesses into which the two light source holders 111a and 111b of the entrance holder 103 are inserted are formed as follows. That is, the recesses are formed so that the traveling directions of the laser beams emitted from the laser chips 112a and 112b of the light source holders 111a and 111b have an angular difference in both the sub-scanning direction and the main scanning direction orthogonal to the sub-scanning direction. It is

FIG. 3C is a perspective view showing the shape of the light source holder 111 to which the laser chip 112 is attached. The light source holder 111 has three cylindrical portions 117, 118 and 119 having different diameters and lengths but having the same central axis. As for the diameter of the cylindrical portions, the cylindrical portion 117 has the largest diameter, and the cylindrical portions 119 and 118 decrease in order. When the light source holder 111 is attached to the incident portion holder 103, the cylindrical portions 117 and 119, which are the positioning surfaces of the light source holder 111 with respect to the incident portion holder 103, are aligned with the positioning surfaces 115a, 115b, 115c and 115d. That is, the cylindrical portion 117 of the light source holder 111 contacts the positioning surfaces 115a and 115b of the incident portion holder 103 shown in FIG. 115d. As a result, the light source holder 111 is fixed while being positioned on the entrance holder 103 . Further, the light source holder 111 is fixed not only by pressing by the light source pressing member 113 but also by an adhesive to the incident portion holder 103 . That is, an adhesive is applied to the adhesive fixing portion 116 (FIG. 3B) of the incident portion holder 103, and after the light source holder 111 is installed on the incident portion holder 103, the adhesive is cured. As a result, the surface 120 of the light source holder 111 in contact with the adhesive fixing portion 116 is fixed by the adhesive (FIG. 3A).

[Light source pressing member]
4A and 4B are diagrams for explaining the pressing force that the light source holders 111a and 111b receive from the light source pressing member 113 and the reaction force that the light source holder 103 receives. FIG. 4A is a diagram illustrating how the light source pressing member 113 presses the light source holder 111 attached to the entrance holder 103. FIG. The light source pressing member 113 is screwed to the entrance holder 103 . The light source pressing member 113 has pressing portions 113 a and 113 b for pressing the mounted light source holders 111 a and 111 b against the incident portion holder 103 . 4A, the pressing portion 113a presses the cylindrical portion 118a of the mounted light source holder 111a toward the positioning surfaces 115a and 115c and the positioning surfaces 115b and 115d of the incident portion holder 103. In FIG. Similarly, the pressing portion 113b presses the cylindrical portion 118b of the mounted light source holder 111b toward the positioning surfaces 115a and 115c and the positioning surfaces 115b and 115d of the incident portion holder 103. As shown in FIG. 4A shows forces Fa and Fb that the cylindrical portions 118a and 118b of the light source holders 111a and 111b receive from the light source pressing member 113. FIG. The light source pressing member 113 presses the two light source holders 111a and 111b toward the incident portion holder 103, and the pressing direction is approximately midway between the positioning surfaces 115a and 115b.

FIG. 4B is a diagram for explaining the reaction force that the light source holder 111 receives from the incident portion holder 103 due to the pressing force F that the light source holder 111 receives from the light source pressing member 113 . The light source holder 111 a receives force Fa from the light source pressing member 113 . Therefore, reaction forces H1a and H2a are received in the direction perpendicular to the positioning surfaces 115b and 115a at the locations where the cylindrical portion 117a of the light source holder 111a and the positioning surfaces 115b and 115a of the incident portion holder 103 contact each other. Similarly, reaction forces H1a and H2a are received in the direction perpendicular to the positioning surfaces 115d and 115c at the locations where the cylindrical portion 119a of the light source holder 111a and the positioning surfaces 115d and 115c of the incident portion holder 103 contact each other.

The light source holder 111b also receives force Fb from the light source pressing member 113 in the same manner. Therefore, reaction forces H1b and H2b are received in a direction perpendicular to the positioning surfaces 115b and 115a at the locations where the cylindrical portion 117b of the light source holder 111b and the positioning surfaces 115b and 115a of the incident portion holder 103 contact each other. Similarly, reaction forces H1b and H2b are received in the direction perpendicular to the positioning surfaces 115d and 115c at the locations where the cylindrical portion 119b of the light source holder 111b and the positioning surfaces 115d and 115c of the incident portion holder 103 contact each other.

FIG. 4(c) is a diagram for explaining the reaction force H2 that the light source holder 111 receives from the positioning surface 115a of the incident portion holder 103 in FIG. 4(b). FIG. 4C shows the reaction force H2 divided into the main scanning direction and the sub-scanning direction. That is, the reaction force H2a that the light source holder 111a receives from the positioning surface 115a of the entrance holder 103 is divided into a force H2ab divided in the main scanning direction and a force H2aa divided in the sub-scanning direction. Similarly, the reaction force H2b that the light source holder 111b receives from the positioning surface 115a of the entrance holder 103 is divided into a force H2bb divided in the main scanning direction and a force H2ba divided in the sub-scanning direction.

As shown in FIG. 4B, the reaction forces H1a and H1b are oriented in the sub-scanning direction because the positioning surfaces 115b and 115d are perpendicular to the sub-scanning direction. Therefore, the light source holder 111a receives forces in opposite directions in the sub-scanning direction by the reaction force H1a and the reaction force H2aa. Similarly, the light source holder 111b receives forces in opposite directions in the sub-scanning direction by the reaction forces H1b and H2ba. As a result, even if the vibration generated by the rotation of the motor unit of the deflector 43 that drives the rotating polygon mirror 42 is transmitted through the optical box 101 and the like and reaches the light source holder 111, the light source holders 111a and 111b are not in the sub-scanning state. You can prevent it from vibrating in any direction.

As described above, according to this embodiment, it is possible to prevent the light source holder holding the semiconductor laser from vibrating in the sub-scanning direction. In particular, in this embodiment, the light source holder holding structure in which the central axis of the light source holder (the optical axis of the laser) does not vibrate in the sub-scanning direction is configured by only an elastic member without using a member that engages with the light source holder. there is By configuring the light source holder as a positioning surface that receives a reaction force from the positioning surface in the sub-scanning direction, it is possible to prevent the central axis of the light source holder from vibrating in the sub-scanning direction. In addition, since the incident portion holder is positioned in the housing, the optical scanning device can be made compact.

40 optical scanning device 103 incident portion holder 111 light source holder 112 laser chip 113 light source pressing member 115 positioning surface

Claims (5)

An optical scanning device to which a support member for supporting a light source holder mounted with a laser chip that emits laser light is attached,
The light source holder has a cylindrical shape, and includes a first cylindrical portion provided on one end side to which the laser chip is mounted, a second cylindrical portion provided on the other end side and having a diameter smaller than that of the first cylindrical portion; has
The support member includes a first positioning surface and a second positioning surface that contact the first cylindrical portion and a third positioning surface and a fourth positioning surface that contact the second cylindrical portion when the light source holder is supported. a positioning surface; and a pressing member installed on the supporting member to press the light source holder against the first positioning surface, the second positioning surface, the third positioning surface, and the fourth positioning surface;
the first positioning surface, the second positioning surface, the third positioning surface, and the fourth positioning surface are planes formed on the support member;
an angle formed by the first positioning surface and the second positioning surface is an acute angle;
an angle formed by the third positioning surface and the fourth positioning surface is an acute angle;
The optical scanning device, wherein the first positioning surface and the third positioning surface are planes perpendicular to a sub-scanning direction orthogonal to a main scanning direction in which the laser beam scans the surface to be scanned. The supporting member has the first positioning surface, the second positioning surface, the third positioning surface and the fourth positioning surface so that the optical axis of the laser beam has an angular difference in the sub-scanning direction and the main scanning direction. 2. The optical scanning device according to claim 1, wherein a positioning surface positions the light source holder. 3. The optical scanning device according to claim 1, wherein the light source holder is fixed to the support member with an adhesive. 4. The optical scanning device according to claim 1, wherein the pressing member is a leaf spring. An image forming apparatus for forming an image on a recording medium,
An image forming apparatus comprising the optical scanning device according to claim 1 .

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