JP2001033718A - Multibeam scanning optical device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily exchange a laser beam source. SOLUTION: A pin part 52a is provided to project backward from the unit attaching part 52 of a jig. In the case of completing a laser unit 22, the unit 22 is attached to the attaching part 52 of the jig 51 and rotated nearly around an optical axis so as to set a pitch P in a subscanning direction to a specified one. In such a state, the projection part 55c of a positioning plate 55 is made to abut on the pin part 52a of the attaching part 52, and the plate 55 is fixed on the holder 42 through a fixing screw 56. A pin part equivalent to the pin part 52a of the attaching part 52 of the jig 51 is provided on the optical box. In the case of attaching the unit 22 to the optical box, the projection part 55c of the plate 55 integral with the unit 22 is made to abut on the pin part of the optical box and the unit 22 is fixed in the optical box.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-beam scanning optical apparatus used in a laser beam printer or the like, which deflects a plurality of light beams by a rotating polygon mirror and simultaneously scans a plurality of lines on a non-scanning surface. Things.

[0002]

2. Description of the Related Art In a typical conventional multi-beam scanning optical apparatus, a laser unit 2 is mounted on an optical box 1 as shown in FIG. 8, and laser light emitted from the laser unit 2 is transmitted through a cylindrical lens 3. The light converges in only one direction by being transmitted, and is condensed linearly on the mirror surface 4 a of the polygon mirror 4. The polygon mirror 4 is supported by a rotating shaft of a scanner motor 5, and can rotate at a high speed in the direction A. The laser light reflected by the image effective portion of the mirror surface 4a of the polygon mirror 4 is deflected and scanned at a constant angular velocity according to the rotation of the polygon mirror 4, passes through the fθ lens including the spherical lens 6 and the toric lens 7, and An image of a minute spot is formed thereon, and the photosensitive drum 8 is repeatedly scanned in the B direction at a constant speed.

The laser light deflected at the image non-effective portion of the mirror surface 4a of the polygon mirror 4 passes through a fixed mirror 9 for light detection and a condensing lens 10 to a timing sensor 1.
1, and the timing sensor 11 converts the optical signal into an electric signal. The electric signal from the timing sensor 11 is used to prevent the timing of repeatedly writing information from shifting due to a division error of the mirror surface 4a of the polygon mirror 4.

[0004] As shown in FIG. 9, in a laser unit 2, a semiconductor laser light source 12 is supported by a holder 13, for example, two light emitting points 12 a and 12 b of the light source 12.
Are housed in the stem 12c. A lens barrel 14 having an aperture stop 14a is fitted to the barrel 13a of the holder 13, and a collimator lens 15 is held inside the lens barrel 14. A drive circuit board 16 for driving the light source 12 is fixed to the holder 13.

The light emitting points 12a, 12a of the laser unit 2
The laser light diverging from b is converted into parallel light by passing through the collimator lens 15, and becomes laser light E and F having a shape according to the aperture stop 14a. Then, the laser beams E and F emitted from the laser unit 2 travel as described above to form an image on the photosensitive drum 8 as two spots E'F 'as shown in FIG. , Two lines having a predetermined pitch P are simultaneously main-scanned.

The main scanning means that the laser beams E and F are deflected while being modulated on / off according to image information, and the light emitting points 12a and 12b are turned on individually or simultaneously as necessary. / Off to emit laser beams E and F. When adjusting the pitch P of the spots E'F 'in the sub-scanning direction by the laser beams E and F, the holder 13 is usually rotated around the optical axis using an image processing device and a jig, The holder 13 is positioned with high precision and fixed to the optical box 1.

[0007]

However, in the above-mentioned conventional example, the laser unit 2 has two light emitting points 12a,
12b, the holder 13 is rotated with respect to the optical box 1 by using an image processing device and a jig, and the holder 13 is accurately positioned even when the laser unit 2 is replaced with the optical box 1. There is a need. Therefore, the user of the image forming apparatus equipped with the conventional scanning optical device cannot replace only the laser unit 2 and must replace the scanning optical device when the laser unit 2 needs to be replaced. However, there is a problem that maintenance cost is increased.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a multi-beam scanning optical device that can easily replace a laser light source.

[0009]

In order to achieve the above object, a multi-beam scanning optical apparatus according to the present invention comprises a holding member holding at least one laser light source for emitting a plurality of light beams in an optical box. Attaching and deflecting means for deflecting a light beam emitted from the laser light source,
A focusing means for focusing the light beam deflected by the deflecting means on the surface to be scanned; and a focusing means for shifting the scanning position of the light beam focused on the surface to be scanned by a predetermined pitch in the sub-scanning direction. In a multi-beam scanning optical device that simultaneously performs main scanning of a plurality of lines, an adjustable member that can adjust the predetermined pitch by setting a predetermined positional relationship with a part of the optical box is attached to the holding member. It is characterized by the following.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a plan view of the embodiment. A laser unit 22 that emits, for example, two laser beams as parallel light is attached to a predetermined position of an optical box 21. In the traveling direction of the laser light emitted from the laser unit 22, a cylindrical lens 23 for converging the laser light in only one direction and a polygon mirror 24 for deflecting the laser light from the cylindrical lens 23 are arranged in the optical box 21. , Polygon mirror 24
Are supported by the drive motor 25.

In the traveling direction of most of the laser light deflected by the polygon mirror 24, a spherical lens 26 and a toric lens 27 constituting an fθ lens are disposed in the optical box 21, and the photosensitive drum 28 is Is located outside. In order to detect a part of the laser beam deflected by the polygon mirror 24, a fixed mirror 29, a condenser lens 30 and a timing sensor 31 are disposed in the optical box 21, and a cover (not shown) is placed on the optical box 21. Is equipped.

The laser unit 22 has a plurality of light emitting points and emits laser light.
A holder 42 for holding the light source 41 by press fitting or the like, a collimator lens 43 for converting the laser light emitted from the light source 41 into a parallel state, an aperture stop 44 for determining the shape of the laser light from the collimator lens 43, and a light source. And a drive circuit board 45 for driving the drive circuit 41. The collimator lens 43 is held by a lens barrel 46, and the lens barrel 46 is fitted to the cylindrical portion 42 a of the holder 42. The drive circuit board 45 is fixed to the rear surface of the holder 42 with fixing screws or the like.

In the laser unit 22, a plurality of laser beams are emitted in a divergent state from a light source 41, are transmitted through a collimator lens 43, become parallel, and are emitted in a shape according to an aperture stop 44. The laser light emitted from the laser unit 22 is converged in only one direction by transmitting through the cylindrical lens 23, and is condensed linearly on the mirror surface 24 a of the polygon mirror 24.

The polygon mirror 24 is rotated at a high speed in the direction C by the driving force of the driving motor 25, and most of the laser light reflected on the mirror surface 24a of the polygon mirror 24 passes through the spherical lens 26 and the toric lens 27. The light passes through and forms a minute spot on the photosensitive drum 28.
The laser beam deflected and scanned at a constant angular speed by the polygon mirror 24 passes through the spherical lens 26 and the toric lens 27 to repeatedly scan the photosensitive drum 28 in the D direction at a constant speed.

On the other hand, the mirror surface 24 of the polygon mirror 24
A part of the laser light reflected by a enters the timing sensor 31 via the fixed mirror 29 and the condenser lens 30, and the timing sensor 30 converts an optical signal into an electric signal. The electric signal output from the timing sensor 30 is used to prevent the timing of repeatedly writing information from being shifted due to a division error of the mirror surface 24a of the polygon mirror 24.

FIG. 2 is a perspective view for explaining a method of manufacturing the laser unit 22. The jig 51 is provided with a unit mounting portion 52 for mounting the laser unit 22. Further, the jig 51 is provided with a cylindrical lens 23 ′, a polygon mirror 24 ′, a spherical lens 26 ′, and a toric lens 27 ′ similar to the multi-beam scanning optical device of the present embodiment. Then, the photosensitive drum 28
Is located at a position corresponding to the camera 5 via the objective lens 53.
The camera 54 can detect the pitch P of the two spots LD1 and LD2 of the laser beam in the sub-scanning direction as shown in FIG.

As shown in FIG. 4, a pin portion 52a projects rearward from the unit mounting portion 52 of the jig 51, and an L-shaped positioning is provided on the rear surface of the holder 42 of the laser unit 22. The plate 55 is fixed. The positioning plate 55 includes a base 55b having two screw holes 55a,
Projection 55c extending perpendicular to base 55b
And is fixed to the holder 42 by two fixing screws 56.

When completing the laser unit 22,
The laser unit 22 is attached to the unit mounting portion 52 of the jig 51.
It is attached by fitting. Next, laser unit 2
2 is rotated about the optical axis, and the pitch P in the sub-scanning direction is set to a predetermined value.
c is brought into contact with the pin portion 52a of the unit mounting portion 52.
Then, the two fixing screws 56 are screwed into the screw holes 55a of the positioning plate 55 via the screw insertion holes of the holder 42, and the fixing screws 56 are tightened to fix the positioning plate 55 to the holder 42.

FIG. 5 is a partially enlarged perspective view showing a state in which the laser unit 22 completed as described above is mounted on the optical box 21. The optical box 21 is provided with a pin 52a of a unit mounting portion 52 of a jig 51. The corresponding pin portion 21a is projected. When attaching the laser unit 22 to the optical box 21, the projection 55 c of the positioning plate 55 integrated with the laser unit 22 is brought into contact with the pin 21 a of the optical box 21 to fix the laser unit 22 to the optical box 21.

As described above, in the first embodiment, the holder 42
The positioning plate 55 attached to the
The laser unit 22 can be attached to the optical box 21 at an angle around the optical axis similar to the angle around the optical axis adjusted by the jig 51 by abutting the laser unit 22 on the optical box 21. Therefore, the pitch P in the sub-scanning direction can be automatically set, and it is not necessary to readjust the laser unit 22 on the optical box 21, and the laser unit 22 can be easily replaced.

In the first embodiment, the case where two laser beams are emitted from one semiconductor laser light source 41 has been described.
It goes without saying that the present invention can be applied to a case where one to a plurality of laser beams, that is, a so-called multi-beam is emitted.

FIG. 6 is a partial perspective view of the second embodiment.
In the first embodiment, the space in the optical axis direction is limited,
This corresponds to a case where it is impossible to provide the pin portion 21a in the optical axis direction. That is, the optical box 21 ′ is provided with the reference projection 21 b in a direction orthogonal to the optical axis, and the projection 55 c of the positioning plate 55 is provided so as to project from the holder 42.

When attaching the laser unit 22 to the optical box 21 ', the tool T1 is interposed between the projection 55c of the positioning plate 55 and the reference projection 21b of the optical box 21', and after the laser unit 22 is positioned. Optical box 2
Fix to 1 '. The second embodiment has the same effect as the first embodiment except that the tool T1 is required.

FIG. 7 is a partial perspective view of the third embodiment.
As in the case of the second embodiment, a case where the positioning plate 55 cannot be protruded from the holder 42 due to space limitations is provided. The optical box 21 ″ is provided with a reference plate 21 d having a surface as a reference surface 21 c, and a positioning member 57 having a flat portion 57 a is rotatably attached to the holder 42.
The plane portion 57a of the positioning member 57 is adjusted so as to be parallel to the jig T2 and the reference surface 21c when the pitch P in the sub-scanning direction is set to a predetermined distance.

When the laser unit 22 is mounted on the optical box 21 ", the tool T2 is interposed between the reference surface 21c of the optical box 21" and the flat portion 57a of the positioning member 57, and the laser unit 22 is rotated around the optical axis. Then, it is fixed to the optical box 21 ". The third embodiment has the same effect as the second embodiment.

[0026]

As described above, in the multi-beam scanning optical device according to the present invention, the sub-scanning position on the surface to be scanned by the light beam is determined by setting the relationship between a part of the optical box and the predetermined position. Adjustable members that set the pitch are provided on the holding member, so the position of the plurality of light beams in the sub-scanning direction can be set to a predetermined pitch simply by replacing the holding member holding the laser light source with the optical box. The laser light source can be easily replaced, and the maintenance cost can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a plan view of a first embodiment.

FIG. 2 is an explanatory diagram of a method for manufacturing a laser unit.

FIG. 3 is an explanatory diagram of a pitch in a sub-scanning direction.

FIG. 4 is a partially enlarged perspective view of a fixed state of a positioning plate.

FIG. 5 is an explanatory diagram of a method of mounting a laser unit.

FIG. 6 is an explanatory diagram of a method of mounting a laser unit according to a second embodiment.

FIG. 7 is an explanatory diagram of a mounting method of a laser unit according to a third embodiment.

FIG. 8 is a plan view of a conventional example.

FIG. 9 is a perspective view of a conventional laser unit.

FIG. 10 is an explanatory diagram of a pitch in a sub-scanning direction of a conventional example.

[Explanation of symbols]

 21, 21 ', 21 "optical box 22 laser unit 24 polygon mirror 25 drive motor 26 spherical lens 27 toric lens 28 photoconductor drum 41 semiconductor laser light source 42 holder 55 positioning plate 57 positioning member

Claims (3)

[Claims] 1. A deflecting means for attaching a holding member holding at least one laser light source for emitting a plurality of light beams to an optical box, and deflecting the light beam emitted from the laser light source; A light-condensing means for condensing the deflected light beam on the surface to be scanned is attached to the optical box, and the scanning position of the light beam condensed on the surface to be scanned is shifted by a predetermined pitch in the sub-scanning direction. In a multi-beam scanning optical device that simultaneously main scans a line,
The multi-beam scanning optical device according to claim 1, wherein an adjustable member that adjusts the predetermined pitch by setting a predetermined positional relationship with a part of the optical box is attached to the holding member. 2. The projection device according to claim 1, wherein the protection member is projected from an optical axis direction of a light beam emitted from the laser light source.
The multi-beam scanning optical device according to claim 1, wherein a part of the adjustable member is projected. 3. The multi-beam scanning optical device according to claim 1, wherein a part of the adjustable member abuts a part of the optical box.