JP2000162526A - Optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical scanner constituted so that dust or the like is perfectly prevented from entering the inside of a housing and thermal deformation amount can be suppressed to the minimum. SOLUTION: The structure of the housing 14 is hollow. Then, a light source unit 28, a rotary polygon mirror 12 and an (Fθ) lens 52 are fitted to the inside of the housing 14 through fitting ports 22, 24 and 26. By fitting the unit 28, the mirror 12 and the lens 52 to the fitting ports in such a way, the housing 14 is hermetically sealed. Since the housing 14 is not constituted so that the aperture part of the housing is closed by a cover being as the separated body in a conventional way but constituted so that the substance corresponding to the cover is integrated with it, the dust or the like hardly enters the inside of the housing 14. Besides, since the housing 14 is integrally molded, a weak position in strength does not exist. Thus, the sufficient strength and sufficient rigidity are obtained with respect to the thermal deformation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device mounted on an image forming apparatus using an electrophotographic process technology.

[0002]

2. Description of the Related Art As shown in FIG. 9, a light scanning device 140 has a light source 1 on a bottom wall 144 of a housing 142 having an open top.
46, a rotary polygon mirror 148, and a type in which the optical component 150 is assembled (see JP-A-4-190264).

[0003] In this optical scanning device 140, the upper part of a housing 142 is open, so that an optical component 150 is made of toner or dust.
May be contaminated, making it impossible to expose the surface of the photoconductor 152 with laser light.

Further, when the image forming apparatus is in use, the self-heating (rotating polygon mirror 148) of the optical scanning device 140 has
, And the heat generated from the electric circuit and the fixing device, the temperature inside the apparatus rises, and the housing 142 is bent or deformed.

[0005] Therefore, the mounting angle of the optical component 150 disposed in the housing 142 changes, and the optical axis of the laser light changes, so that the laser light deviates from the optical component 150 in the housing 142, The optical axis of the laser light emitted toward the body 152 may be deviated, and image quality may be degraded.

[0006] In order to solve the above inconvenience, FIG.
As shown in FIG. 7, there is an optical scanning device 158 in which an opening of a housing 156 is closed by a lid 154 (see Japanese Patent Application Laid-Open No. 7-225348).

[0007] However, even if the opening is closed by the lid 154, it cannot be completely sealed, and dust or the like enters through a gap between the lid 154 and the housing 156. In addition, although the thermal deformation of the housing 156 can be suppressed to some extent by the lid 154, only the screwed portion is restricted, and sufficient strength and rigidity against deformation cannot be obtained.

[0008]

SUMMARY OF THE INVENTION In consideration of the above-mentioned facts, the present invention provides an optical scanning device capable of almost completely preventing dust or the like from entering a housing and minimizing the amount of thermal deformation. The task is to provide.

[0009]

According to the first aspect of the present invention, the housing has a hollow structure, and the light source, the light deflecting means, and the optical component are mounted inside through the mounting opening. The housing is hermetically sealed by attaching the light source, the light deflecting means, and the optical component to the mounting opening as described above.

That is, unlike the conventional case, the opening of the housing is not closed with a separate lid, but the housing corresponding to the lid is integrated, so that dust and the like hardly enter. In addition, since the housing is integrally formed and there is no weak portion in strength, sufficient strength and rigidity against thermal deformation can be obtained.

According to the second aspect of the present invention, an opening for attaching a light source, an opening for attaching a light deflecting unit for deflecting a light beam from the light source, and a light beam deflected by the light deflecting unit are scanned. An aperture for mounting a lens that forms an image on the
A housing provided with the opening of the light deflecting means on one of two surfaces sandwiching the main scanning plane, and the other of the two surfaces sandwiching the main scanning plane of the housing Are formed integrally and covered.

[0012] In the above configuration, 2 is provided to sandwich the main scanning plane of the housing.
An opening of the light deflecting means is provided on one of the surfaces, and the opening is closed by attaching the light deflecting means. Further, since the other of the two surfaces sandwiching the main scanning plane of the housing is integrally formed, sufficient strength and rigidity against thermal deformation can be obtained.

According to the third aspect of the present invention, the bottom surface of the housing is placed on the main body frame of the image forming apparatus, and the top surface of the housing is restrained by the elastic means fixed to the main body frame. I have. For this reason, as compared with the type in which the housing is fixed to the main body frame with screws, the housing placed on the main body frame and restrained by the surface expands and contracts uniformly as a whole, and partially expands and contracts. Since expansion and contraction are not restricted, it does not bend or deform. The amount of expansion and contraction of the housing is absorbed by the elastic means being elastically deformed.

According to the fourth aspect of the invention, the positioning pin is integrally formed on the bottom surface of the housing, and the main body frame is provided with an elongated hole for movably engaging the positioning pin.

[0015] For this reason, the housing is positioned on the main body frame by engaging the positioning pins with the elongated holes.
Further, since the pin can move through the elongated hole, even if the housing is thermally expanded, the pin is not restrained and thermally deformed.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an optical scanning device 10 according to a first embodiment comprises a top wall 16, a bottom wall 18, and a side wall 2.
0 is integrally formed of a resin material.

The rotating polygon mirror 12 is provided on the bottom wall 18 of the housing 14.
The front side wall 20 has a rectangular mounting port 24 to which an Fθ lens 52 is mounted, and the side wall 20 has a casing 30 of the light source unit 28. Is formed in a circular mounting port 26 to which the.

Further, from both ends of the side wall 20, the housing 14
Of the image forming apparatus is formed as a fixed portion when screwed to a main body frame 34 (see FIG. 6) of the image forming apparatus.

On the other hand, as shown in FIG. 2, a cylindrical metal casing 30 is inserted into the mounting port 26, and the mounting port 26 is hermetically sealed without any gap, whereby the position of the casing 30 is determined. . A lens housing 36 is formed on the distal end side of the casing 30, and two collimator lenses 40 are housed with a ring-shaped spacer 38 interposed therebetween.

A female screw 42 is formed on the inner wall from the lens housing 36 to the rear end. This female screw 4
A ring-shaped lens retainer 44 is screwed into the distal end side of 2 to fix the collimator lens 44.

Further, the female screw 42 is screwed with a metal cylindrical body 48 having a male screw 46 formed on the outer peripheral portion. A laser diode 50 is provided at the rear end of the cylindrical body 48.
The distance between the laser diode 50 and the collimator lens 40 is adjusted by changing the screwing amount between the male screw 46 and the female screw 42.

A coil spring 54 is arranged between the casing 30 and the cylindrical body 48 to eliminate play between the male screw 46 and the female screw 42. After the adjustment is completed, the male screw 46 and the female screw 42 are fixed with a screw fixing agent.

Further, at the rear end of the cylindrical body 48, a printed board 56 is provided. This printed circuit board 56
Is connected to a later-described printed board 58 by a flexible printed board harness (not shown), and a wiring 61 extending from an electric terminal of the laser diode 50 serves as an intermediary role for easily connecting to the flexible printed board harness. Fulfill.

The printed circuit board 56 is sandwiched between the cylindrical body 48 by a holding block 60, and the cylindrical body 48 and the holding block 60 are fixed by screws 62. A leaf spring 64 projects obliquely rearward from the rear end of the holding block 60. The free end of the leaf spring 64 is
The screw 65 is fixed to the top wall 66A of the housing 66 which covers the mounting opening 26 by surrounding the holding block 60 and urges the holding block 60 toward the top wall 66A.

Further, a screw hole is formed in the top wall 66A of the housing 66, and a set screw 68 is screwed therein. The tip of the set screw 68 is in contact with the center of the holding block 60.

With this configuration, the set screw 68 is connected to the leaf spring 6.
4 is screwed against the urging force of the collimator lens 40.
And the laser diode 50 are integrally moved to the inside of the housing 14 (to the side of the rotary polygon mirror 12).
When the collimator lens 4 is loosened,
0 and the laser diode 50 move integrally (in a direction away from the rotary polygon mirror 12) inside the housing 14. Thus, the distance between the rotary polygon mirror 12 and the light source unit 28 can be adjusted. The play of the set screw 68 is absorbed by the leaf spring 64.

On the other hand, a flange 70 projects from the opening edge of the housing 66 described above. This flange 7
At 0, a mounting hole 72 is formed, which is engaged with a positioning pin 74 formed integrally with the side wall 20 to be positioned. The flange 70 is fixed to the side wall 20 with a screw.

Thus, the collimator lens 40 and the laser diode 5 disposed inside the housing 66
0 is fixed to the housing 14, and the final positioning of the laser beam becomes possible. The printed board 58 for driving the laser diode 50 is also positioned on the housing 14 by the positioning pins 74.

As shown in FIGS. 1 and 3, the mounting opening 22 has escaped to the inside of the housing 14 and has a base member 76 to be described later.
Are not projected from the bottom wall 18. A positioning pin 78 protrudes from the periphery of the mounting port 22.

The positioning pin 78 includes a rotating polygon mirror 1
The positioning hole 80 formed in the base member 76 is inserted in a state where 2 is inserted into the inside of the housing 14 through the mounting port 22. The base member 76 is provided with a motor 82 for rotating the rotary polygon mirror 12 at high speed.
And is fixed to the bottom wall 18 by screws.

As a result, the mounting opening 22 is hermetically sealed by the packing 84 and the base member 76 without any gap.
Is also positioned.

On the other hand, as shown in FIGS. 1 and 4, rectangular locking holes 86 are formed in the bottom wall 18 and the top wall 16 that define the mounting port 24. In the locking hole 86, a claw piece 94 punched out on the upper plate 90 and the lower plate 92 constituting the holder 88 is locked.

A frame 96 whose center is cut out is provided on the side surface of the holder 88, and serves as a laser light passing window. The lower plate 92 is provided with three columnar projections 98 so as to draw a triangle. The projection 98 has F
The θ lens 52 is placed and positioning in the height direction is performed. A pressing leaf spring 95 is formed on the upper plate 90 so as to face the projection 98. The pressing plate spring 95 presses the upper surface of the Fθ lens 52, and the Fθ lens 52 is fixed in the holder 88.

Further, a column-shaped projection 102 is provided on the lower side of the lower plate 92 at the center. This protrusion 102
Engages with a long hole 104 formed on the lower surface of the Fθ lens 52 to enable the Fθ lens 52 to move in the optical axis direction and to perform positioning in the lateral direction. Lens 52 is laterally urged by a leaf spring 100 hanging down from the upper plate 90 to perform lateral positioning.

On the other hand, the frame body 96 is a packing 1 having a rectangular frame shape.
At 06, it is sandwiched from both sides, and is pressed together with the Fθ lens 52 against a step portion 108 formed on the back side of the mounting port 24.

In addition, elongated holes 110 are formed at both ends of the upper plate 90 and the lower plate 92. When the holder 88 holding the Fθ lens 52 is attached to the mounting port 24 from the outside, the positioning pin 114 which is engaged with the circular hole 112 formed in the top wall 16 and the bottom wall 18 is inserted into the long hole 110. Is done.

The positioning pins 114 position the Fθ lens 52 in the optical axis direction, and prevent the holder 88 from being pushed out of the mounting port 24 by the elastic force of the packing 106.

As described above, the mounting ports 22, 24,
Since the casing 14 having only the opening 26 is integrally formed, there is no weak point in strength, and sufficient strength and rigidity against thermal deformation can be obtained. In addition, with the unique mounting structure of the light source unit 28, the rotary polygon mirror 12, and the Fθ lens 52, it is possible to prevent intrusion of dust and the like from each mounting port.

Next, the difference between the amount of thermal deformation between the conventional case 120 to which the lid 118 is fixed later and the case 14 of the present embodiment as shown in FIG. Was.

Here, the housing of the present embodiment and the housing of this embodiment are the main body frame.
The distance L between the fixing points fixed to the system is 133 mm, the housing is made of Noryl (trade name) containing glass fiber, and the coefficient of thermal expansion is 3 × 10 ⁻⁵ . The coefficient of thermal expansion of the main frame was 0, and the temperature in the apparatus was 35 ° C to 60 ° C.

At this time, the side wall 134 of the conventional housing 120
Angle (tilt angle with respect to the vertical plane) is 0.0761
°, the falling angle of the housing 14 of the present embodiment is 0.0395 °, and a difference of 0.0366 ° occurs.

Also, the amount of lifting of the bottom wall (the amount of deflection at the center of the bottom wall that rises in a drum shape with the fixed point as a fulcrum).
Is as small as 0.08109 mm in the conventional housing 120 and 0.06919 mm in the housing 14 of the present embodiment.

As described above, the housing 14 of the present embodiment can minimize the amount of deformation due to thermal expansion without using any special member or device, and can reduce the amount of laser light emitted toward the photosensitive member. Does not cause any deviation in the optical axis.

Next, an optical scanning device according to a second embodiment will be described.

In the second embodiment, as shown in FIGS. 5 and 6, a positioning pin 122 for positioning is projected from the bottom wall 17 of the housing 138. This positioning pin 122
Are located on a line M connecting the center of the Fθ lens 52 to the center of the rotary polygon mirror 12 (see FIG. 1), and are disposed at two places near the Fθ lens 52 and near the rotary polygon mirror 12.

On the other hand, the main frame 34 has a circular hole 12 into which the positioning pin 122 is inserted and fixed on the Fθ lens 52 side.
4 has a positioning pin 12 on the rotary polygon mirror 12 side.
A long hole 123 with which the second member 2 is movably engaged is formed.

Thus, when the housing 138 is thermally expanded, it is thermally deformed along a line M connecting the center of the Fθ lens 52 to the center of the rotary polygon mirror 12.

The lower surface of the bottom wall 17 of the housing 138 is flat and is directly mounted on the main frame 34.
A metal band 128 buried in an elastic member 126 such as rubber is wound around the top wall 15 of the housing 138.

Both ends of the band 128 are connected to the body frame.
The band 128 is fixed to the housing 34 with a screw 130 via an elastic member 126 and uniformly presses the housing 138.

With this method of fixing the housing 138, as compared with the first embodiment in which the housing 14 is fixed to the main body frame 34 with screws, as shown in an exaggerated manner in FIG.
The entire housing 138 constrained by the surface expands and contracts uniformly, and the expansion and contraction is not partially restricted, so that the housing 138 does not bend or deform. The amount of expansion and contraction of the housing 138 is absorbed by the elastic deformation of the elastic member 126.

Further, the housing 138 has no unevenness in the portion in contact with the elastic member 126, and the pressing force acts evenly, so that the housing 138 is not easily deformed.

[0052]

According to the present invention having the above-described structure, dust and the like hardly enter, and sufficient strength and rigidity against thermal deformation can be obtained.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view illustrating a housing of an optical scanning device according to a first embodiment.

FIG. 2 is a cross-sectional view showing a mounting structure of a light source unit of the optical scanning device according to the first embodiment.

FIG. 3 is a sectional view showing a mounting structure of a rotary polygon mirror of the optical scanning device according to the first embodiment.

FIG. 4 is a cross-sectional view illustrating a mounting structure of an Fθ lens of the optical scanning device according to the first embodiment.

FIG. 5 is a plan view showing a mounting structure of an optical scanning device according to a second embodiment.

FIG. 6 is a cross-sectional view illustrating a mounting structure of an optical scanning device according to a second embodiment.

FIG. 7 is an explanatory diagram showing a change in thermal expansion of the optical scanning device according to the second embodiment.

FIG. 8 is a perspective view showing a conventional optical scanning device to be compared.

FIG. 9 is a perspective view showing a conventional optical scanning device.

FIG. 10 is a sectional view showing a conventional optical scanning device.

[Explanation of symbols]

 Reference Signs List 12 light deflecting means (rotating polygon mirror) 14 case 28 light source unit (light source) 52 Fθ lens (optical component) 122 positioning pin 123 long hole 126 elastic member 128 case

Claims (4)

[Claims] 1. An optical scanning system comprising: a light source for generating laser light; a light deflecting unit for deflecting the laser light; and an optical component for forming an image of the laser light deflected by the light deflecting unit on a photosensitive member. In the apparatus, the light source, the light deflecting means, and a housing in which a mounting port to which the optical component is mounted are formed in an integrally formed hollow structure, and the light source, the light deflecting means, and An optical scanning device, wherein the housing is hermetically closed by attaching the optical component. 2. An opening for mounting a light source, an opening for mounting light deflecting means for deflecting a light beam from the light source, and a lens for forming an image of the light beam deflected by the light deflecting means on an object to be scanned. An opening; and a housing provided with the opening of the light deflecting means on one of the two surfaces sandwiching the main scanning plane, the two surfaces sandwiching the main scanning plane of the housing. An optical scanning device, wherein the other inner surface is integrally formed and covered. 3. The image forming apparatus according to claim 2, wherein a bottom surface of the housing is mounted on a main body frame of the image forming apparatus, and a top surface of the housing is restrained by an elastic means fixed to the main body frame. The optical scanning device according to claim 1 or 2. 4. The optical scanning device according to claim 3, wherein a positioning pin is integrally formed on a bottom surface of the housing, and an elongated hole is formed in the main body frame so that the positioning pin is movably engaged. apparatus.