KR100412495B1 - multi-beam laser scanning apparatus - Google Patents

Abstract

The multi-beam optical scanning device according to the present invention comprises a plurality of light sources; An optical deflector for deflecting the plurality of light fluxes emitted from the plurality of light sources; And a reflecting surface that reflects the first light flux emitted from a portion of the plurality of light sources at a predetermined position and angle, the first light flux reflected from the reflecting surface and the second light flux emitted from the rest of the plurality of light sources An optical system for incident light for guiding, to the optical deflector, a plurality of light fluxes emitted from a plurality of light sources having a prism for combining and emitting at a predetermined exit position and angle; The incident light optical system is configured to adjust the emission position and angle between the first and second light fluxes emitted from the prism by adjusting the angle and position of the reflecting surface and / or prism. Therefore, the multi-beam optical scanning device of the present invention has an optical system for incident light composed of a prism and / or a reflecting surface which can adjust the position and angle, so that it is easy to manufacture without requiring many components, and that light flux synthesis and light flux There is an effect that the direction and angle can be adjusted efficiently.

Description

Multi-beam laser scanning apparatus

The present invention relates to a multi-beam optical scanning device that can be used in an image forming apparatus applied to a printer, a facsimile, a copier, and the like, and more particularly, a multi-beam optical fiber that can efficiently adjust the synthesis and the direction and angle of the light flux. It is about a private device.

In general, a multi-beam optical scanning device used in an image forming apparatus such as a printer, a facsimile machine, a copier, or the like is used to form an electrostatic latent image of an image on a photosensitive member such as a photosensitive drum or a photosensitive belt at a high speed. A plurality of light sources generating the same light flux are used.

The multi-beam optical scanning device combines a laser beam generated from a plurality of light sources, such as a semiconductor laser diode, through a collimator lens or a prism complex, and converts the laser beam into parallel light having a predetermined interval, thereby rotating at a high speed. After inducing, deflecting the reflection direction of the laser beam in a rotating mirror, a plurality of printed lines are simultaneously scanned on the photosensitive member through a scanning lens such as an f-theta lens to form an electrostatic latent image.

1 and 2, a general multi-beam optical scanning device 10 for forming an electrostatic latent image on a photosensitive member and an optical system for incident light constituting the same are schematically illustrated.

The optical scanning device 10 includes first and second semiconductor lasers 1a and 1b capable of emitting first and second laser beams, and first and second electrodes corresponding to the semiconductor lasers 1a and 1b, respectively. Light synthesizing and adjusting unit 3 for synthesizing the first and second laser beams passing through the two collimator or coupling lenses 2a and 2b and the first and second coupling lenses 2a and 2b and outputting them at predetermined intervals A light having a cylindrical lens 4 for producing a linear image arranged along the path of the first and second laser beams, and a rotating multifaceted mirror 5a for deflecting the reflection directions of the first and second laser beams. A deflector 5.

As shown in FIG. 2, the photosynthesis and adjusting unit 3 includes a half wave plate 16 and a reflecting surface 17 for rotating the second laser beam that has passed through the second coupling lens 2b by 90 °. A first coupling prism 15 provided at an end of the first prism 15 having both ends inclined at 45 ° and the first prism 15 provided with the polarization separation film 18 respectively forming the polarization separation film 18 A second prism 15 'composed of a right angle prism incident at right angles to the first laser beam passing through 2a), and formed on an exit surface of the first prism 15 from which the first and second laser beams are emitted; And an opening controller 19 for shaping the first and second laser beams.

The optical deflector 5 includes a rotating multifaceted mirror 5a which is supported by the spindle motor 14 and driven to rotate in the direction of the arrow A at high speed.

First and second F-theta lenses 6a and 6b for correcting errors included in the first and second laser beams deflected by the rotating polygon mirror 5, and the first and second F-theta lenses 6a. , The optical scanning part including a reflector 9 reflecting the first and second laser beams passing through 6b) to the surface to be scanned of the surface of the photosensitive member such as the photosensitive drum 20, is provided on the deflection plate of the rotating multifaceted mirror 5a. Disposed on the path of most of the first and second laser beams deflected by it. In addition, the mirror 8 is disposed on the paths of the part of the first and second laser beams passing through the end of the second f-theta lens 6b, and the synchronization signal sensor 11 is provided by the mirror 8. Disposed on the paths of the reflected first and second laser beams.

Referring to the operation of the conventional multi-beam optical scanning device 10 configured as described above, the second laser beam emitted from the second semiconductor laser 1b and modulated according to the input image signal is applied to the second coupling lens 2b. Parallel to, converging, or diverging, S (TE) polarized light by being incident at right angles to the incident surface of the first prism 15, passing through the half wave plate 16, and turning the polarization plane by 90 °. Thereafter, the second laser beam is reflected at right angles from the reflective surface 17 toward the polarization splitting film 18, and then reflected back at right angles from the polarizing splitting film 18, at a right angle from the exit surface of the first prism 15. It is emitted.

On the other hand, the first laser beam emitted from the first semiconductor laser 1a passes through the first coupling lens 2a and enters the incidence plane of the second prism 15 'at right angles to the polarization splitting film 18. After passing through, it exits at right angles from the exit surface of the first prism 15.

The first and second laser beams, which are separated from each other with a predetermined distance from the first prism 15, pass through the opening controller 19 for shaping the shape of the laser beam, and then the spindle via the cylindrical lens 4 The motor 14 collides with and deflects the deflection plate of the rotating multifaceted mirror 5a which rotates at a high speed in the direction of the arrow A. FIG. The first and second laser beams are then reflected by the reflector 9 via the first and second F-theta lenses 6a, 6b, and then on the scan surface of the photosensitive drum 20 It collects as a light spot and scans two printing lines 7 along the main scanning direction. At this time, the photosensitive drum 20 is driven to rotate in the direction of the arrow B by a driving motor (not shown), so that the photosensitive drum 20 according to the scanning motion of the light spots along the main scanning direction and the sub scanning direction. As a result of the movement of the latent electrostatic image is formed on the photosensitive drum (20).

On the other hand, some of the first and second laser beams deflected by the rotating polygon mirror 5a are reflected by the mirror 8, transmitted to the synchronization signal generating circuit 23 through the synchronization signal sensor 11, and synchronized. The signal generation circuit 23 generates a synchronization signal. The synchronization signal generated by the synchronization signal generation circuit 23 is input to the central processing unit 12, and the central processing unit 12 controls the scanning start timing and the image formation timing of the light spots on the scan surface.

However, the conventional multi-beam optical scanning device 10 operating as described above has a half wave plate 16, a prism 15 having a reflecting surface 17 and a polarization separating film 18, and a right angle prism 15 '. Since the complicated light synthesizing and adjusting unit 3 composed of) is used, the following problems may occur.

First, when each component of the light synthesizing and adjusting unit 3 is manufactured separately, when the angle or length error due to the manufacturing error occurs, the emission angles and spacings between the laser beams to be synthesized are different from each other. There was a problem of deterioration.

Second, in order to configure the light synthesizing and adjusting unit 3, a plurality of components such as a half wave plate 16, a reflecting surface 17, a polarization separating film 18, a prism 15, and a right angle prism 15 ' This necessitates an increase in manufacturing cost and the need to join these parts together, which may lead to defects due to the prism angle and the joining error.

Third, in the case of component manufacturing or assembly error, the method of adjusting the light synthesizing and adjusting unit 3 rotates the semiconductor lasers 1a and 1b constituting the light source in a diagonal direction or the light synthesizing and adjusting unit 3. Since there is only a method of rotating the at an angle, there was a problem that the error adjustment or correction is almost impossible.

Finally, the first laser beam emitted from the first semiconductor laser 1a is passed using the polarization separator 18 and the second laser beam emitted from the second semiconductor laser 1b is reflected to generate two laser beams. By combining, there is a problem that the polarization direction between the laser beams is different, in this case, if the transmittance for each polarization direction of the other optical component is different, the beam intensity on the scan surface is different from each other may be a direct factor that degrades the image quality.

The present invention has been made to solve the above problems, and the object of the present invention is not only easy to manufacture because it requires a large number of parts, but also can synthesize the light flux and efficiently adjust the direction and angle of the light flux. It is to provide a multi-beam optical fiber.

Another object of the present invention is to provide a multi-beam optical scanning device that can actively adjust the errors in the manufacturing and assembly of parts by using the position and angle of the prism and / or reflecting surface.

1 is a perspective view illustrating a schematic arrangement of a conventional multi-beam optical scanning device.

FIG. 2 is a plan sectional view of an optical system for incident light of the multi-beam optical scanning device shown in FIG. 1; FIG.

3 is a perspective view illustrating the arrangement of a multi-beam optical scanning device in accordance with the present invention;

4 is a schematic plan sectional view of an optical system for incident light of the multi-beam optical scanning device shown in FIG.

* Description of the symbols for the main parts of the drawings *

1a, 1b, 101a, 101b: semiconductor lasers 2a, 2b, 102a, 102b: coupling lenses

3, 103: light combining and adjusting section 4, 104: cylindrical lens

5, 105: optical deflector 5a, 105a: rotating face mirror

6a, 6b, 106a, 106b: f-theta lens 7, 107: printing line

8, 108: mirror 9, 109: reflector

10, 100: Optical scanning device 11, 111: Sync signal sensor

12: central processing unit 14, 114: motor

15, 15 ', 116: Prism 16: 1/2 wave plate

17, 117: reflecting surface 18: polarization separator

19: aperture controller 20, 120: photosensitive drum

23: synchronization signal generating circuit 116a: incident surface

116b: exit surface 118: transmission / reflection portion

121: case 122: circuit board

In order to achieve the above object, the present invention is a plurality of light sources; An optical deflector for deflecting the plurality of light fluxes emitted from the plurality of light sources; And a reflecting surface that reflects the first light flux emitted from a portion of the plurality of light sources at a predetermined position and angle, the first light flux reflected from the reflecting surface and the second light flux emitted from the rest of the plurality of light sources Multi-beams for scanning the scanning surface with a plurality of light fluxes comprising an optical system for incident light for guiding a plurality of light fluxes emitted from a plurality of light sources having a prism to synthesize and emit at a predetermined exit position and angle In the optical scanning device, the incident light optical system adjusts the emission position and angle between the first and second laser beams emitted from the prism by adjusting the angle and position of the reflecting surface and / or prism. to provide.

In a preferred embodiment, the plurality of light sources consists of a plurality of semiconductor lasers mounted at regular intervals on the same plane of the circuit board.

The prism is fixedly adjustable to adjust the position and angle, and adjusts the distance between the first and second light flux emitted from the prism through the position adjustment, and the angle between the first and second light flux through the angle adjustment. Is adjusted to an angle that is parallel, convergent or divergent.

In addition, the first and second light fluxes incident on the prism are configured to be emitted after being reflected or refracted at least twice. To this end, the incident optical system reflects the second light flux incident through the prism and at the same time enters the first light flux reflected through the reflecting surface at an angle having the same or predetermined angle difference as that of the second laser beam. And a transmission / reflection portion that refracts and transmits, and the prism has an incident surface for injecting a second light flux to refracted at a predetermined angle toward the transmission / reflection portion, and first and second light transmitted and reflected through the transmission / reflection portion, respectively. And an exit surface for exiting the flux by refracting the flux at a predetermined angle. The transmission / reflection portion is composed of a member that changes the polarization direction of the preset light flux or adjusts transmission and reflectance. In addition, the prism is preferably formed of glass or plastic material.

The reflective surface is fixedly adjustable to adjust the position and angle, and adjusts the distance between the first and second light fluxes emitted from the prism through the position adjustment, and between the first and second light fluxes through the angle adjustment. Adjust the angle to parallel, convergent or divergent angles.

In the multi-beam optical scanning device of the present invention, the incident light optical system further includes a lens for making a plurality of light fluxes emitted from the plurality of light sources in parallel, converging or diverging light.

The lens, prism, and reflecting surface further have a member for increasing the transmittance or reflectance of the light flux. In addition, the plurality of light sources, lenses, prisms, and reflecting surfaces are preferably fixed by the same support member to prevent performance degradation due to positional variations between structures.

Hereinafter, with reference to the accompanying drawings will be described in detail with respect to the accompanying drawings multi-beam optical scanning device according to a preferred embodiment of the present invention.

3 and 4, the multi-beam optical scanning device 100 and the incident optical system constituting the same according to the present invention are shown, respectively.

The multi-beam optical scanning device 100 of the present invention includes a metal can or a case 121 (FIG. 4), first and second semiconductor lasers 101a and 101b for emitting first and second laser beams, and each semiconductor laser. The first and second laser beams passing through the first and second collimators or coupling lenses 102a and 102b and the first and second coupling lenses 102a and 102b disposed corresponding to 101a and 101b. A light synthesizing and adjusting unit 103 for synthesizing and adjusting the light, and a cylindrical lens 104 for generating a linear image arranged along a path of the first and second laser beams, and the first and second laser beams. And an optical deflector 105 having a rotating polyhedron 105a for deflecting the reflection direction thereof.

The first and second semiconductor lasers 101a and 101b are mounted at regular intervals on the same plane of the circuit board 122 disposed in the case 121 to have a circuit configuration and design margin.

The first and second coupling lenses 102a and 102b have an aspherical or spherical shape and are formed of glass or plastic material. These lenses 102a and 102b serve to make the first and second laser beams emitted from the first and second semiconductor lasers 101a and 101b into predetermined light, that is, light that is parallel, converging or diverging. .

As shown in FIG. 4, the light synthesizing and adjusting unit 103 adjusts to reflect the first laser beam emitted from the first semiconductor laser 101a and passed through the first coupling lens 102a at a predetermined position and angle. And a second laser beam emitted from the reflective surface 117 and the second semiconductor laser 101b and having passed through the second coupling lens 102b to be combined with the first laser beam reflected from the reflective surface 117. And the first laser beam reflected through the reflective surface 117 is incident and refracted and transmitted at a predetermined angle while the second laser beam is incident through the prism 116. The laser beam consists of a transmission / reflection portion 118 formed on one side of the prism 116 to reflect at a predetermined angle.

The reflective surface 117 is fixedly installed to be adjusted through adjustment means such as a screw (not shown), a lever (not shown), etc. in the case 121 to adjust the reflection angle and position. Accordingly, the distance L between the first and second laser beams emitted from the prism 116 is adjusted by adjusting the position of the reflecting surface 117, and parallel, converging or diverging the angle between the first and second laser beams. Adjusting to the angle can be adjusted through the angle of the reflective surface 117.

The prism 116 refracts the incident surface 116a for injecting the second laser beam and refracting it at a predetermined angle, and the first and second laser beams transmitted and reflected through the transmission / reflector 118, respectively, at a predetermined angle. And an exit surface 116b to exit. The prism 116 is preferably formed of glass or plastic material.

Optionally, the prism 116 may be fixed to be adjustable through screws or fixing holders (not shown), etc. to adjust the exit position and angle between the first and second laser beams. In this case, similar to the reflective surface 117, the distance L between the first and second laser beams emitted from the prism 116 may be adjusted by adjusting the position of the prism 116, and the first and second laser beams may be adjusted. Adjusting the angle between the beams to an angle that is parallel, converging or diverging can be adjusted through the angle adjustment of the prism 116.

The transmission / reflector 118 that transmits the first laser beam installed on one side of the prism 116 and reflects the second laser beam may change the polarization direction of the laser beam by a predetermined amount to equalize the amount of light emitted from the laser beam. It consists of members that change or adjust the transmission and reflectance.

As such, the first and second laser beams emitted from the first and second semiconductor lasers 101a and 101b and incident on the prism 116 through the first and second coupling lenses 102a and 102b are prisms. It is reflected or refracted at least two times through the entrance surface 116a, the transmission / reflection portion 118 and the exit surface 116b until exit through the exit surface 116b of 116 and exit.

In more detail, as illustrated in FIG. 4, the second laser beam incident to the prism 116 after passing through the second coupling lens 102b may have an index of refraction determined by the material of the prism 116. By adjusting the position and angle of the prism 116 is reflected or refracted at least two times at the desired angle from the desired position to exit. In the exemplary embodiment of the present invention, the light is refracted once in the incident surface 116a, and then reflected once in the transmissive / reflective portion 118 and refracted in the adjacent exit surface 116b. Meanwhile, the first laser beam that passes through the first coupling lens 102a and then enters the reflecting surface 117 is incident on the reflecting surface 117 at a predetermined angle, and is then transmitted and installed on one side of the prism 116. It is incident on the / reflective unit 118 at a predetermined angle. The first laser beam passing through the transmission / reflection portion 118 is incident on the prism 116 and refracted with the same or predetermined angle difference as that of the second laser beam, and then the exit surface 116b of the prism 116. It is refracted through and exits.

In the multi-beam optical scanning device of the present invention, the first and second coupling lenses 102a and 102b, the prism 116, and the reflecting surface 117 each have a member capable of increasing the transmittance or reflectance of the laser beam. Can be installed additionally. In addition, these devices are preferably fixed by the same support member together with the first and second semiconductor lasers 101a and 101b in order to prevent performance degradation due to positional variations between structures.

Referring again to FIG. 3, the cylindrical lens 104 is disposed in front of the light deflector 105 to produce a linear image by exhibiting a predetermined refractive effect for the first and second laser beams.

The rotating polygon mirror 105a constituting the optical deflector 105 is supported by the spindle motor 114 to be driven to rotate in the direction of the arrow A at high speed, and deflects the first and second laser beams to the deflection plate. Let's do it.

In addition, the multi-beam optical scanning device 100 of the present invention, the first and second F-theta lenses 106a and 106b for correcting errors included in the first and second laser beams deflected by the rotating polygon mirror 105a. And a reflector 109 that reflects the first and second laser beams that have passed through the first and second F-theta lenses 6a and 6b to the scan surface of the photosensitive member such as the photosensitive drum 120. Contains the master. This optical scanning part is disposed on the path of most of the first and second laser beams deflected by the deflection plate of the rotating polygon mirror 105a.

The mirror 108 is disposed on some paths of the first and second laser beams passing through the end of the second f-theta lens 106b, and the synchronizing signal sensor 111 for scanning synchronization is provided to the mirror 108. Disposed on the paths of the first and second laser beams reflected by it.

As described above, the multi-beam optical scanning device 100 of the present invention is composed of only a prism having an incident surface for adjusting the position and angle of the light synthesizing and adjusting unit 103 constituting the incident light optical system, and a transmission / reflection portion. In addition, it is easy to manufacture, and the synthesis of the laser beam and the direction and angle of the laser beam can be adjusted efficiently.

The operation of the multi-beam optical scanning device 100 according to the present invention configured as described above will be described in detail with reference to FIGS. 3 and 4 as follows.

First, the second laser beam emitted from the second semiconductor laser 101b is made of light that is paralleled, converged or diverged by the second coupling lens 102b. Then, the second laser beam is incident on the incident surface 116a of the prism 116 at a predetermined angle and refracted according to the refractive index determined by the material of the prism 116 and the angle of the prism 116, and then the prism ( The light incident on the transmissive / reflective portion 118 provided on one side of 116 is reflected at a predetermined angle, and is refracted by the adjacent exit surface 116b and exits.

At this time, the first laser beam emitted from the first semiconductor laser 101a is made of light that is paralleled, converged or diverged by the first coupling lens 102a. After passing through the first coupling lens 102a, the first laser beam is incident and reflected by the reflective surface 117 at a predetermined angle, and then incident again by the transmission / reflective portion 118 at a predetermined angle. Thereafter, the first laser beam is incident on the prism 116 and is refracted with the same or predetermined angle difference as that of the second laser beam, and is then refracted and exited again through the exit surface 116b of the prism 116. . At this time, if the positions of the reflective surface 117 and / or prism 116 are adjusted, the path of the first laser beam passing and refracting through the prism 116 through the transmission / reflection portion 118 is changed to be emitted. It is possible to adjust the distance L between the first and second laser beams.

In this way, the first and second laser beams are combined in the light synthesizing and adjusting unit 103 and are separated from each other at a small interval in parallel with each other and in a sub-scan direction.

Thereafter, the emitted first and second laser beams enter the rotating polygon mirror 105a via the cylindrical lens 104. The rotating polygon mirror 105a is driven to rotate at high speed by the spindle motor 114 in the direction of the arrow A to deflect the first and second laser beams by the deflection plate. Accordingly, the first and second laser beams pass through the F-thetas 106a and 106b and are reflected by the reflector 109, and then converge as a plurality of light spots on the scan surface of the photosensitive drum 120. do. The light spots scan the print line 107 along the main scanning direction as the two laser beams are deflected. In this case, when an interval error between the scan lines forming the print line 107 occurs, when the angles of the reflective surface 117 and / or the prism 116 are adjusted, the first and second lasers emitted from the prism 116 The angles that parallel, converge or diverge the angles between the beams can be adjusted and corrected.

On the other hand, the photosensitive drum 120 is driven to rotate in the direction of the arrow B by the drive motor, and moves relative to the light spots along the sub-scanning direction. Thus, the electrostatic latent image is formed on the photosensitive drum 120 as a result of the scanning movement of the light spots along the main scanning direction and the movement of the photosensitive drum 120 along the sub scanning direction.

At this time, some of the first and second laser beams deflected by the rotating polygon mirror 105a are reflected by the mirror 108 and received by the synchronization signal sensor 111. A synchronization signal generation circuit (not shown) connected to the synchronization signal sensor 111 generates a synchronization signal in accordance with the output of the synchronization signal sensor 111. The synchronization signal generated by the synchronization signal generation circuit is input to a central processing unit (not shown), which controls the scanning start timing and the image formation timing of the light spots on the scan surface.

As described above, the multi-beam optical scanning device according to the present invention does not require components such as a right angle prism, a half wave plate, and the like, and is easy to manufacture, and also the synthesis of the laser beam and the direction and angle of the laser beam. It provides an effect that can be adjusted efficiently.

In addition, the multi-beam optical scanning device of the present invention can be obtained by adjusting the angle of the prism and / or the reflecting surface in the same optical scanning device to ensure that the laser beams have the same exit angle and spacing, it is possible to obtain excellent image quality .

In addition, the multi-beam optical scanning device of the present invention by using the position and angle of the prism and / or reflecting surface can actively adjust the error in manufacturing and assembly, thereby providing a design and assembly margin.

In the above, certain preferred embodiments of the present invention have been illustrated and described. However, the present invention is not limited to the above-described embodiments, and any person having ordinary skill in the art to which the present invention pertains without departing from the scope of the present invention as claimed in the claims may make various modifications and variations. Would be possible.

Claims (12)

A plurality of light sources; An optical deflector for deflecting a plurality of light fluxes emitted from the plurality of light sources; And a reflecting surface that reflects the first light flux emitted from a portion of the plurality of light sources at a predetermined position and angle, and the first light flux reflected from the reflecting surface and the second light emitted from the rest of the plurality of light sources. The plurality of light fluxes comprising an optical system for incident light for guiding the fluxes to the light deflector and guiding the plurality of light fluxes emitted from the plurality of light sources having a prism for injecting and synthesizing the flux and emitting at a predetermined exit position and angle In the multi-beam optical scanning device for scanning the scanning surface, The incident light optical system may adjust an emission position and an angle between the first and second light fluxes emitted from the prism by adjusting an angle and a position of at least one of the reflective surface and the prism. Beam optical scanning device. The multi-beam optical scanning device of claim 1, wherein the plurality of light sources comprise a plurality of semiconductor lasers mounted at regular intervals on the same plane of the circuit board. The method of claim 1, wherein the prism is fixed to adjust the position and the angle, to adjust the distance between the first and second light flux emitted from the prism through the position adjustment, and through the angle adjustment And adjusting the angle between the first and second light fluxes to be parallel, convergent or divergent. 4. The multi-beam optical scanning device of claim 3, wherein the first and second light fluxes incident on the prism are configured to be emitted after being reflected or refracted at least twice. The method of claim 4, wherein The optical system for incident light reflects the second light flux incident through the prism and simultaneously enters the first light flux reflected through the reflecting surface to achieve the same or predetermined angle difference as that of the second laser beam. A multi-beam optical scanning device characterized in that it further comprises a transmission / reflection unit that is transmitted by refracting at an angle having. The method of claim 5, wherein the prism, An incidence surface incident on the second light flux and refracting at a predetermined angle toward the transmission / reflection portion; And And an emission surface for refracting the first and second light fluxes transmitted and reflected through the transmission / reflection portion at a predetermined angle, respectively. The multi-beam optical scanning device of claim 6, wherein the prism is formed of glass or plastic material. The multi-beam optical scanning device according to claim 5, wherein the transmission / reflection unit is composed of a member for changing a polarization direction of a preset light flux or adjusting transmission and reflectance. The method of claim 1, wherein the reflective surface is fixed to adjust the position and the angle, to adjust the distance between the first and second light flux emitted from the prism through the position adjustment, the angle adjustment And adjusting the angle between the first and second light fluxes to be parallel, convergent or divergent. The multi-beam optical scanning device of claim 1, wherein the optical system for incident light further comprises a lens for making the plurality of light fluxes emitted from the plurality of light sources in parallel, converging or diverging light. . The multi-beam optical scanning device of claim 10, wherein the lens, the prism, and the reflecting surface each include a member for increasing the transmittance or reflectance of the light flux. 12. The multi-beam optical scanning device of claim 11, wherein the plurality of light sources, the lens, the prism, and the reflecting surface are fixed by the same support member to prevent performance degradation due to positional variations between structures. .