JP2002040344A - Optical path separation device for optical scanner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical path separation device for an optical scanner for which a nearly correct reflection surface can be obtained by easily and uniformly vapor-depositing aluminum on a long-length base material. SOLUTION: Long-length reflection mirrors 11 and 12 are opened with an angle of approximately 120 deg. from a closed state where the reflection surfaces 11a and 12a are faced to each other so as to be overlapped. In this case, each end part E of reflection mirrors 11 and 12 is abutted to each other. The reflection mirrors 11 and 12 are so arranged that the center line O of incident light beams L1 and L2 passes through the end part E and the mirrors are symmetrical with respect to the center line O. The incident light beams L1 and L2 are reflected upon the reflection surfaces 11a and 12a, respectively, become the reflected light beams M1 and M2, cross approximately on the center line O, are made incident onto successive optical elements, cylindrical mirrors 13 and 14, for example, and reflected in a proper direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for irradiating a plurality of image carriers such as photoreceptor drums with laser beams to form electrostatic latent images of the same or different colors on the respective image carriers. The toner image formed from the electrostatic latent image is
The present invention relates to an optical scanning device suitable for an image forming apparatus that forms a desired image on a transfer medium by sequentially transferring the transfer medium while moving the transfer medium, and in particular, separates a plurality of optical paths formed substantially in parallel into optical paths in different directions. The present invention relates to an optical path separating device of an optical scanning device suitable for the above.

[0002]

2. Description of the Related Art As a color image forming apparatus such as a color copying machine or a color printer, a so-called tandem type image forming apparatus is widely known. This involves arranging a plurality of image carriers such as photoreceptor drums in parallel, irradiating each of these image carriers with a laser beam while scanning them, and forming an electrostatic latent image. An image forming apparatus adopting a method in which a toner image is formed by developing with a toner, and a color image is formed by sequentially transferring the toner image to a transfer medium such as recording paper moving in a direction in which the image carriers are arranged. It is.

As a general image forming apparatus of this type, for example, there is one described as an optical scanning system in JP-A-11-295625. Such a general tandem type image forming apparatus includes Y (yellow),
Laser beams emitted from four laser light sources corresponding to M (magenta), C (cyan), and BK (black) image data are respectively exposed on four photosensitive drums via scanning optical systems corresponding to the respective laser beams. Thus, an electrostatic latent image is formed.

In such a color image forming apparatus, separate scanning optical systems are provided for a plurality of photosensitive drums, so that miniaturization of the apparatus is hindered and the cost may be increased. There is. For this reason, a single scanning optical system is commonly used for a plurality of photosensitive drums, and a compact color image forming apparatus is disclosed in Japanese Patent Laid-Open No. Hei 6-2862.
26, JP-A-10-20608, JP-A-1-20608
No. 0-133131. The optical scanning device used in these color image forming apparatuses deflects laser beams emitted from a plurality of laser light sources corresponding to the number of the plurality of photoconductors to a separating unit by a deflecting unit that deflects in common, The separation means guides each laser beam to each photoconductor.

The applicant of the present invention has developed a separation polygon mirror having a structure capable of processing with high accuracy by a simple operation as the separation means, and has already filed a patent application for an optical scanning device using this separation polygon mirror. (Japanese Patent Application No. 11-341150)
issue). FIGS. 5 and 6 show a separating polygon mirror developed for the optical scanning device. 4 emitted from laser light source 21
The laser beam is adjusted to a parallel beam by a collimator lens 22 and a cylindrical lens 24,
The light is sequentially reflected by the reflection mirror 23 and the second reflection mirror 25 and enters a polygon mirror 26 serving as a deflecting unit. The laser beam reflected by the polygon mirror 26 passes through the fθ lenses 27a and 27b and enters the separation polygon mirror 28. As shown in FIG. 5, the laser beams incident in parallel are first separated into two beams by two in two directions as shown in FIG.
3 and 34 are separated one by one in four directions. These four
The laser beams in the directions are the first guide mirror 31 and the first cylindrical mirror 36, the second guide mirror 32 and the second cylindrical mirror 37, the third guide mirror 33 and the third cylindrical mirror 38,
An optical path is secured so that the light is sequentially reflected by the fourth guide mirror 34 and the fourth cylindrical mirror 38 and enters an image carrier (not shown).

[0006] As shown in FIG.
The section is formed in a substantially square shape, and is disposed substantially parallel to the radial direction of the polygon mirror 26. The reflecting surfaces 28a and 28b of the separating polygon mirror 28 are formed by surfaces including two adjacent sides of the square. Therefore, processing of these two surfaces is easy and can be performed with high accuracy.

[0007]

However, the above-described separation polygon mirror 28 has the following problems when processing a long one. The reflecting surface of the separation polygon mirror 28 may be processed by evaporating aluminum on the surface of the base material and coating the surface.However, a large evaporation furnace capable of performing evaporation on a long base material is expensive. turn into. Moreover, 2
It is difficult to uniformly vapor-deposit the surface. In particular, if a long bending occurs, the deposition on the two surfaces becomes non-uniform. It should be noted that vapor deposition can be performed relatively easily with the short separation polygon mirror 28, and this separation polygon mirror 28 is effective for a small optical scanning device.

Therefore, according to the present invention, even if it is long, the reflection surface can be easily processed uniformly, and the existing vapor deposition furnace can be used, so that the cost does not increase. It is an object of the present invention to provide an optical path separating device for an optical scanning device.

[0009]

As a technical means for achieving the above-mentioned object, an optical path separating device of an optical scanning device according to the present invention scans an object to be scanned with a plurality of light beams individually. In an optical path separation device that separates substantially parallel incident light beams into reflected light beams in appropriate directions so as to irradiate the respective scanned regions, an optical scanning device that forms an electrostatic latent image, wherein the center line of the optical path of the incident light beams is As a symmetry axis, two reflecting mirrors are characterized in that they are symmetrically arranged by being opened at an appropriate angle so that the reflected light beams intersect substantially on the symmetry axis.

[0010] Since the two reflecting mirrors are combined, the respective reflecting mirrors can be individually vapor-deposited. For this reason, the reflecting surface can be processed uniformly, and an existing vapor deposition furnace can be used. Even when processing a long reflecting mirror, the cost does not increase. Since the directions of the two reflecting surfaces are different from each other with respect to the axis of symmetry, incident light rays are reflected in different directions.
By adjusting the direction of the reflecting surface, the light can be reflected in a desired direction.

The optical path separating device of the optical scanning device according to the second aspect of the present invention is characterized in that the two reflecting mirrors are arranged with their respective edges abutting.

That is, two reflecting surfaces are arranged such that the edges of the reflecting surfaces are brought into contact with each other, and the axis of symmetry passes through the contacting portions.

According to a third aspect of the present invention, in the optical path separating device of the optical scanning device, the two reflecting mirrors are arranged such that one end thereof is in contact with an edge of the other reflecting surface. Features.

That is, one reflecting mirror is brought into contact with the reflecting surface of the other reflecting mirror, and the two reflecting mirrors are arranged so that the axis of symmetry passes through the abutting edge.

The optical path separating device of the optical scanning device according to the invention of claim 4 is characterized in that the two reflecting mirrors are opened at substantially 120 degrees.

That is, the two reflecting mirrors are arranged in an open state so as to be at 60 degrees from the symmetry axis.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an optical path separating device of an optical scanning device according to the present invention will be specifically described based on the illustrated preferred embodiments. In this embodiment, a case where two parallel light beams are separated will be described.

FIG. 1 is a diagram showing an optical scanning apparatus.
Is deflected by a polygon mirror, etc.
Two substantially parallel light rays L₁ , L_Two To the optical path separation device 1
Incident. As shown in FIG.
The two reflecting mirrors 11 and 12 are opposed to the reflecting surfaces 11a and 12a.
From the stacked state to the open state at an appropriate angle
Have been. In addition, this opening degree is almost 120 degrees.
If each reflected light M ₁ , M_Two Interferes with reflectors 11 and 12
Never do.

The reflecting mirrors 11 and 12 are arranged so that their respective edges E are in contact with each other, so that the center lines O of the parallel light beams L ₁ and L ₂ pass through the edges E. It is. Further, the two reflecting mirrors 11 and 12 are arranged symmetrically with the center line O as the axis of symmetry.

According to this embodiment configured as described above,
The operation of the optical path separating device of the optical scanning device will be described below.
You. Two rays L adjusted in parallel₁ , L_Two Is in it
Whether the core wire O passes through the edge E of the optical path separating device 1
Ray L₁ Represents the light beam L_Two Is the reflector 12
Each is incident. Then, the reflected light beam M reflected by the reflecting mirror 11
₁ Is the reflected light M reflected by the reflecting mirror 12 toward the reflecting mirror 12_Two 
Are guided to the side of the reflecting mirror 11, respectively. These reflected light M
₁ , M_Two Is a subsequent optical element, for example, as shown in FIG.
The light enters the cylindrical mirrors 13 and 14. These syrins
The rays reflected by the mirrors 13 and 14 are flat at appropriate intervals.
Rows, each of which is incident on the object to be scanned.
You.

The structure shown in FIG. 1 and the conventional structure shown in FIG.
Compare with structure. In any case, from the reflective surface to the scanned object
Have the same optical path length. As shown in FIG.
In the optical path separation device, the incident light L
₁ , L_Two Is reflected almost at right angles to the cylindrical mirror
-41 and 42. For this reason, light incident on the object to be scanned
Line spacing is D₁ Becomes On the other hand, according to the present invention,
In the optical path separating device, as shown in FIG.
The optical path from a to the cylindrical mirrors 13 and 14 is incident light.
Line L₁ , L_Two At an acute angle to the center line O
Crosses and reaches cylindrical mirrors 13 and 14. this
Therefore, the interval between light beams incident on the object to be scanned is D _Two (<D₁ )
Becomes In other words, while securing the optical path length,
The spacing can be reduced and the width of the optical scanning device can be reduced.
Can be. Further, the reflected light M at the reflecting mirrors 11 and 12
₁ , M_Two Is the incident light L₁ , L_Two Is reflected on the side of
Reduce the distance from the optical path separating device 1 to the object to be scanned.
Can be. Therefore, the size of the optical scanning device can be reduced.
be able to.

FIG. 3 is a diagram showing another embodiment of the optical path separating device of the optical scanning device according to the present invention. In this embodiment, a structure in which the end of the reflecting mirror 15 is brought into contact with the edge of the reflecting surface 16a of the reflecting mirror 16 is combined. The abutting edges E are combined so that the center lines O of the incident light beams L ₁ and L ₂ pass.

In the optical path separating device 2 according to the embodiment shown in FIG. 3, the reflected light beams M ₁ and M ₂ are guided so as to intersect substantially on the center line O.

In the embodiment described above, the number of parallel rays is two. However, two or more rays such as four rays may be used. When four light beams are used, the light beam is suitable for a color image forming apparatus. When two light beams are used as in this embodiment, an electrostatic latent image can be simultaneously formed along two scanning lines, and an image is simultaneously formed on a transfer medium corresponding to the two scanning lines. And an image can be formed quickly.

[0025]

As described above, according to the optical path separating device of the optical scanning device according to the present invention, two light reflecting mirrors are combined to separate parallel light rays. The processing of the reflecting mirror can be easily performed. In addition, since the deposition process can be performed almost uniformly on the surface of the base material, a substantially accurate reflecting surface can be obtained. Further, since an existing evaporation furnace can be used, the processing cost does not increase.

According to the optical path separating device of the optical scanning device according to the second or third aspect of the present invention, two reflecting mirrors can be easily combined.

Further, according to the optical path separating device of the optical scanning device according to the fourth aspect of the present invention, it is possible to prevent the light reflected by one reflecting mirror from interfering with the other reflecting mirror.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a state of a light beam separated by an optical path separation device of an optical scanning device according to the present invention.

FIG. 2 is a diagram illustrating a structure of an embodiment of an optical path separation device according to the present invention.

FIG. 3 is a diagram illustrating the structure of another embodiment of the optical path separation device according to the present invention.

FIG. 4 is a diagram for explaining a state of a light beam separated by a conventional optical path separating device, and is a diagram provided for comparison with the structure shown in FIG. 1;

FIG. 5 is a side view schematically showing a structure of an optical scanning device in which a conventional optical path separating device is incorporated.

6 is a plan view of the structure shown in FIG.

[Explanation of symbols]

 1 Optical path separating device 2 Optical path separating device 11 Reflecting mirror 11a Reflecting surface 12 Reflecting mirror 12a Reflecting surface 13 Cylindrical mirror 14 Cylindrical mirror 15 Reflecting mirror 15a Reflecting surface 16 Reflecting mirror 16a Reflecting surface

Claims (4)

[Claims] 1. An optical scanning apparatus which forms an electrostatic latent image by scanning a scanning object separately with a plurality of light beams so as to irradiate substantially parallel incident light beams to respective scanning regions. An optical path separation device that separates reflected light into two reflected mirrors, with the center line of the optical path of the incident light as a symmetric axis, and opening two reflecting mirrors at an appropriate angle so that the reflected light substantially intersects on the symmetric axis. An optical path separating device for an optical scanning device, wherein the optical path separating device is symmetrically arranged. 2. The optical path separation device of an optical scanning device according to claim 1, wherein the two reflecting mirrors are arranged such that their respective edges are in contact with each other. 3. The optical path separation device of an optical scanning device according to claim 1, wherein the two reflecting mirrors are arranged such that one end thereof is in contact with an edge of the other reflecting surface. . 4. An optical path separation device for an optical scanning device according to claim 1, wherein said two reflecting mirrors are opened at substantially 120 degrees.