JP2004272273A - Optical scanning device - Google Patents

Abstract

An optical scanning device that does not require an aperture as an independent component is realized.
A light beam from a light source is coupled by a coupling lens, and the coupled light beam is formed as a long line image in a main scanning corresponding direction by a first image forming optical system. The light is deflected at an equal angular velocity by an optical deflector 16 having a deflecting / reflecting surface in the vicinity of the image forming position, and the deflected light beam is condensed as a light spot on the surface to be scanned by a second image forming optical system 18 to be scanned. In the optical scanning device that performs optical scanning, a housing 20 in which an optical system is provided is molded by a mold and includes a main light beam of a coupled light beam and passes through a main light beam portion forming a light spot. The peripheral light beam shielding portion 17 that blocks the peripheral light beam portion outside the main light beam portion is formed integrally with the housing 20.
[Selection diagram] FIG.

Description

  The present invention relates to an optical scanning device.

  The light beam from the light source is coupled by a coupling lens, and the coupled light beam is formed as a long line image in the main scanning corresponding direction by the first image forming optical system, and is deflected and reflected in the vicinity of the image forming position of the line image. An optical scanning device that deflects a light beam at an equal angular velocity by an optical deflector having a surface, condenses the deflected light beam as a light spot on the surface to be scanned by a second imaging optical system, and performs optical scanning of the surface to be scanned is Are widely known in relation to digital copiers and optical printers.

  In such an optical scanning device, the light spot formed on the surface to be scanned must have a desired spot diameter in both the main and sub scanning directions in order to achieve a desired recording density.

  For this purpose, an aperture is usually arranged on an optical path between the coupling lens and the first imaging optical system to block a peripheral portion of the coupled light beam (Patent Document 1, etc.). ).

  The opening diameter of the aperture in the aperture in the main scanning direction (the direction corresponding to the main scanning direction in parallel with the main scanning direction on a virtual optical path in which the optical path from the light source to the surface to be scanned is linearly developed along the optical axis); The aperture diameter in the sub-scanning corresponding direction (the direction corresponding to the virtual scanning path in parallel with the sub-scanning direction) can adjust the spot diameter of the light spot in the main and sub-scanning directions. By using this, the spot diameter on the surface to be scanned can be stabilized.

  As described above, the use of the aperture is useful for optical scanning. However, since the aperture is an independent component, there are disadvantages such as an increase in the number of components for configuring the optical scanning device, an increase in the number of assembling steps, and an increase in cost.

JP-A-63-51687

  An object of the present invention is to realize an optical scanning device that does not require an aperture as an independent component.

  An optical scanning device according to the present invention is configured such that "a light beam from a light source is coupled by a coupling lens, and the coupled light beam is formed as a long line image in a main scanning corresponding direction by a first imaging optical system. Is deflected at an equal angular velocity by an optical deflector having a deflecting / reflecting surface in the vicinity of the image forming position, and the deflected light beam is condensed as a light spot on the surface to be scanned by the second image forming optical system, and Optical scanning device that performs optical scanning. "

  As the “light source”, a semiconductor laser or a light emitting diode can be effectively used.

  The coupling action of the "coupling lens" may be a collimating action for converting a light beam from the light source into a parallel light beam, a weak divergent light beam, or a weakly convergent light beam.

  The “second imaging optical system” may have a speed equalizing function such as an fθ function that speeds up the main scanning of the surface to be scanned by the light spot, or electrically adjust the modulation speed of the light source. Thus, the pixel density may be constant in the main scanning direction.

  The “first imaging optical system” can be configured as, for example, a concave cylinder mirror, one or more cylinder lenses, or a combination of a cylinder mirror and a cylinder lens. Since the first imaging optical system has the function of “forming a coupled light beam as a long linear image in the main scanning direction” as described above, it is necessary to have a positive power in the sub-scanning direction. However, the main scanning direction may have a weak positive power or a weak negative power.

The optical scanning device according to the first aspect of the present invention has the following features.
That is, the housing in which the optical system is provided is “molded by a mold”, and passes through the “main light beam portion that includes the main light beam of the coupled light beam and forms a light spot”, and A peripheral light beam shielding portion that blocks a peripheral light beam portion outside the portion is formed integrally with the housing.

  In this case, the peripheral light beam shielding portion can be composed of "a plurality of components disposed at different positions on the optical path" (claim 2). In the optical scanning device according to the first or second aspect, the following can be used as the first imaging optical system.

  That is, the first imaging optical system has an “aperture function for restricting a light beam cross section of the coupled light beam”, and at least one surface of the first imaging optical system includes “a principal ray of the coupled light beam. A surface shape that allows the main light beam portion forming the light spot to pass therethrough and reflects or refracts the peripheral light beam portion (in the light beam cross section) outside the main light beam portion in a direction different from that of the main light beam portion. 3).

  In the optical scanning device according to the third aspect, when the first imaging optical system is “configured as a cylinder lens having a positive power only in the sub-scanning corresponding direction”, around the portion that passes the main light beam portion, It may be configured to have a “refractive surface portion for the peripheral light beam portion” that refracts the peripheral light beam portion in a direction different from that of the main light beam portion (claim 4). A "reflection surface" for reflecting the peripheral light beam portion in a direction different from that of the main light beam portion may be formed. In the case of the optical scanning device according to the fifth aspect of the present invention, the reflection by the "reflection surface" can be "total reflection" (claim 6).

  The “surface that refracts or reflects the peripheral light beam portion” of the first imaging optical system is formed so as to refract or reflect the peripheral light beam portion in a direction away from the main light beam portion, and refracts or reflects the peripheral light beam portion. A "light-shielding portion for shielding a peripheral light beam portion" can be formed by printing or coating on a portion outside the surface.

  Hereinafter, a reference technique that can obtain the same effect as the present invention will be described.

  In the optical scanning device of Reference Technique 1, the first imaging optical system has an aperture function of restricting a light beam cross section of the coupled light beam, and at least one surface of the first imaging optical system is “coupled”. A portion including a main beam portion of a light beam and passing a `` main beam portion forming a light spot '', and a peripheral light beam shielding portion that blocks a peripheral light beam portion outside the main light beam portion around this portion, The peripheral light beam shielding portion is formed by printing or coating, and the portion through which the main light beam portion passes is "recessed with respect to the peripheral light beam shielding portion".

  Also in the case of Reference Technique 1, the first imaging optical system can be configured as a cylinder lens having power only in the sub-scanning corresponding direction, but in addition, a concave cylinder mirror, two or more cylinder lenses, and , A combination of a cylinder mirror and a cylinder lens, and may have a weak positive power or a weak negative power in the main scanning corresponding direction. Further, at least a portion having an aperture function of the first imaging optical system can be formed by “molding with plastic”.

  In the optical scanning device according to Reference Technique 2, the housing in which the optical system is provided is “molded by a mold”, and the first imaging optical system is the one described in claim 3, 4, 5, or 6. Thus, a “light-shielding portion that shields a peripheral light beam portion reflected or refracted in a direction different from the main light beam portion” is formed integrally with the housing.

As described above, according to the present invention, a novel optical scanning device can be realized.
In the optical scanning device according to the present invention, the aperture, which has been conventionally required as an independent component, can be omitted, so that the number of components of the optical scanning device can be reduced, the assembly process can be simplified, and the cost can be reduced.

  According to the first and second aspects of the invention, it is possible to realize a stable light spot on the surface to be scanned without increasing the number of parts, and according to the second aspect of the invention, it is possible to simplify the mold structure for forming the housing. Reduction of molding cost can be realized. According to the third aspect of the present invention, the area of the first imaging optical system that reflects or refracts the peripheral light beam portion can be reduced in the projected area on a surface orthogonal to the optical axis, and the peripheral area formed integrally with the housing can be reduced. Since the accuracy of the light beam shielding portion can be made rough, the yield of the housing can be improved and the cost of the housing can be reduced.

Hereinafter, embodiments of the invention will be described.
An example of an optical scanning device to which the present invention can be applied will be described with reference to FIG.

  In FIG. 1A, a light beam emitted from a semiconductor laser 10 as a “light source” is coupled by a coupling lens 12. As described above, the coupled light beam can be a “weakly divergent light beam or a weakly convergent light beam”, but in this embodiment, it is assumed to be a “parallel light beam”. That is, the action of the coupling lens 12 is a collimating action.

  The light beam coupled by the coupling lens 12 is incident on a cylinder lens 14 forming a “first imaging optical system”. The cylinder lens 14 converges the incident parallel light beam only in the sub-scanning corresponding direction (the direction orthogonal to the drawing in FIG. 1A) and the main scanning corresponding direction near the deflecting and reflecting surface of the polygon mirror 16 which is an “optical deflector”. To form a long line image.

  When the polygon mirror 16 rotates at a constant speed in the direction of the arrow, the light beam reflected by the deflecting / reflecting surface becomes a deflecting light beam deflecting at a constant angular velocity. As light. A photoconductive photoreceptor 20 is provided so that the peripheral surface is in contact with the surface to be scanned. Therefore, the light spot is required to scan the peripheral surface of the photoreceptor 20 at a constant velocity in the generatrix direction. become.

  In FIG. 1A, the second imaging optical system (fθ lens 18) is schematically depicted as a single lens. However, when actually configuring the optical scanning device, the second imaging optical system (fθ lens 18) is used. Needless to say, the optical system can be composed of two or more lenses. In the second imaging optical system, a long cylinder lens, a toroidal lens, or the like for conventionally correcting surface tilt and field curvature can be used. It goes without saying that various optical elements known as optical systems may be included.

  The cylinder lens 14 as the “first imaging optical system” is a plano-convex cylinder lens, and the convex surface thereof is directed to the incident side and has “positive power only in the sub-scanning corresponding direction”.

  As described above, in the optical scanning device according to the first aspect, the housing in which the optical system is provided is molded by the mold, and includes the main light beam portion including the main light beam of the coupled light beam and forming the light spot. The peripheral light beam shielding portion that blocks the peripheral light beam portion outside the main light beam portion is formed integrally with the housing.

An embodiment of the optical scanning device according to the present invention will be described with reference to FIG.
In FIG. 7A, reference numeral 20 denotes a housing. As shown, the housing 20 is provided with an optical system such as a light source 10, a collimating lens 12, a cylinder lens 14a as a first imaging optical system, a polygon mirror 16, and an fθ lens 18 as a second imaging optical system. The peripheral light beam shielding portion 17 for passing the “main light beam portion including the principal light beam of the coupled light beam and forming a light spot” and blocking the peripheral light beam portion outside the main light beam portion is connected to the housing 20. It is formed integrally.

FIG. 7B shows a state in which the housing 20 having the peripheral light beam shielding portion 17 is molded by a mold. The four dies 31, 32, 33 and 34 are combined as shown in the figure, and the housing 20 is formed by injection of plastic.
FIG. 7C shows a state in which the dies 31, 32, 33, and 34 have been removed.
The mold 31 forms the bottom surface of the housing 20. The molds 33 and 34 are in contact with each other on a slope, and the mold 34 is first slid along the slope of the mold 33 and removed. Subsequently, the molds 32 and 33 are removed by upward movement. Finally, the housing 20 is removed from the mold 31. Since the die 34 is slid obliquely to remove the mold, the peripheral light beam shielding portion 17 has an opening portion through which the “main light beam portion including the main light beam of the coupled light beam and forming the light spot” passes. As shown in FIG. 7C, a taper is formed.

  FIG. 8 shows an embodiment of the second aspect of the present invention, in which a peripheral light-shielding portion is formed by two components 171 and 172. The components 171 and 172 are provided at different portions on the optical path. The constituent part 171 shields “light beams on both sides in the main scanning corresponding direction” and shields “lower light beams in the sub-scanning corresponding direction”. In addition, the component part 1712 shields the “upper beam part with respect to the sub-scanning corresponding direction”. Therefore, when the two components 171 and 172 forming the peripheral light beam shielding portion are viewed in the optical axis direction from the light source 10 side, the light spot including the principal ray of the coupled light beam as a rectangular opening overlaps each other. Is formed, an opening portion through which a main light beam portion forming the above is passed. The peripheral light beam portion is shielded from light by the components 171 and 172 on the cylinder lens 14a side.

  The housing 21 as shown in FIG. 8A can be formed by two dies 35 and 36 as shown in FIG. 8B, and the dies 35 and 36 are slid only in the vertical direction in FIG. Can be used to remove the mold, and the cost does not increase. If necessary, the peripheral light beam shielding portion may be formed of three or more components.

  In the embodiments shown in FIGS. 7 and 8, the cylinder lens 14a as the first imaging optical element is a normal cylinder lens and does not have an aperture function. Therefore, the aperture function of blocking the peripheral light beam portion is realized by the peripheral light beam blocking portion 17 or 171 or 172. The first imaging optical system described in 6 can also be used.

  Here, an example of the first imaging optical system having the “aperture function for regulating the light beam cross section of the coupled light beam” according to claims 3 to 6 will be described.

  In FIG. 1A, a cylinder lens 14 serving as a “first imaging optical system” is a plano-convex cylinder lens whose convex surface is directed to the incident side and provides “positive power only in the sub-scanning corresponding direction”. Have. A "dent" is formed on the plane lens surface facing the emission side, that is, the polygon mirror 16 side.

  That is, (b-1) in FIG. 1B is a state in which the cylinder lens 14 is viewed from the main scanning corresponding direction, and the right side, that is, the side of the convex surface is the “light incident side”. (B-2) is a view of the cylinder lens 14 seen from the emission side, and (b-3) is a view of the cylinder lens 14 seen from the sub-scanning corresponding direction.

  As shown in (b-2) of FIG. 1B, the “dent” portion is constituted by a rectangular portion 14A corresponding to the bottom and a slope portion 14B surrounding the rectangular portion, and the rectangular portion 14A is formed. Is a plane, which is parallel to the plane of the exit surface of the cylinder lens 14.

  In FIG. 1C, the cylinder lens 14 is virtually cut by “a plane parallel to the main scanning corresponding direction including the optical axis AX”. When the light beam coupled to the parallel light beam by the coupling lens 12 is incident on the cylinder lens 14, the light beam is only incident in the sub-scanning corresponding direction (the direction orthogonal to the drawing in FIG. 1C) by the convex cylinder surface forming the incident surface. The light passes through the cylinder lens 14 while being converged.

  As shown in FIG. 1C, the rectangular portion 14A (the portion hatched by a broken line in (b-2) of FIG. 1B) in the recess formed on the exit side surface of the cylinder lens 14 The slanted portion 14B passes the peripheral light beam portion LB around the main light beam portion LA in a direction different from that of the main light beam portion LA (the main light beam portion LA). (The direction away from the portion LA).

  In this way, of the light beams incident on the cylinder lens 14, only the main light beam portion LA used for forming the light spot travels along the "optical path to the surface to be scanned", and the peripheral light beam portion LB is not affected. It is separated from the optical path leading to the scanning plane. In other words, the cylinder lens 14, which is the first imaging optical system, has an "aperture function for restricting a light beam cross section of the coupled light beam".

  As described above, in the optical scanning device shown in FIG. 1, the cylinder lens 14, which is the first imaging optical system, has a positive power only in the sub-scanning corresponding direction and passes through the main light beam portion LA. A slope portion 14B for the peripheral light beam portion that refracts the peripheral light beam portion LB in a direction different from that of the main light beam portion is provided as a "refractive surface portion" around the periphery 14A (claim 4).

  The spot diameter of the light spot in the main scanning direction and the length of the short side of the light spot are determined by the length of the long side of the rectangular shape (see (b-2) of FIG. 1B) of the portion 14A through which the main beam portion LA passes. Thus, the spot diameter in the sub-scanning direction can be adjusted.

In FIG. 1C, assuming that the inclination angle of the inclined surface portion 14B as the refraction surface portion is θ and the angle between the peripheral light beam portion LB and the principal ray is θ ′, these angles: θ and θ ′ are Satisfying the relationship “θ ′ = sin ⁻¹ (N × sin θ) −θ”, where N is the refractive index of the material of For example, if θ = 30 degrees and N = 1.52, θ ′ is approximately 19.5 degrees, which is sufficient for separating the main beam portion LA and the peripheral beam portion LB.

As the inclination angle θ of the slope portion 14B increases, the angle θ ′ also increases. However, as in the cylinder lens 140 shown in FIG. 2, the inclination angle θ of the slope portion 14B1 further increases and the inequality “θ> When “sin ⁻¹ (1 / N)” is satisfied, the peripheral light beam portion LB of the light beam that is coupled and enters the cylinder lens 140 is totally reflected inside the cylinder lens 14 by the slope portion 14B1, and the bottom of the depression is formed. Is separated from the main light beam portion LA passing through the rectangular portion 14A1.

  That is, in FIG. 2, a peripheral light beam portion is formed around a rectangular portion 14A1, which is a portion through which a main light beam portion passes, of a cylinder lens 140 having a positive power only in a sub-scanning corresponding direction which is a first imaging optical system. The slope portion 14B1 is formed as a reflection surface that reflects the LB in a direction different from the main light beam portion (claim 5), and the slope portion 14B1 that is the reflection surface is a "total reflection surface" (claim 6).

  Even when there is no “inclination angle enough to cause total reflection” in the slope portion, the main beam portion LA is formed by reflecting the peripheral beam portion LB inside the cylinder lens by forming the “reflection film” on the slope portion. Needless to say, it is also possible to separate them from.

  By the way, when the inclination angle θ of the slope portion is increased to increase the separation angle of the peripheral light beam portion LB separated from the main light beam portion LA, the “projection area of the slope portion onto a plane orthogonal to the optical axis” is increased. Is smaller. For this reason, as shown in FIG. 3, when the light beam diameter of the light beam that is coupled and enters the cylinder lens 145 is large, the main light beam portion LA that passes through the rectangular portion 14A2 is “just outside”. A certain peripheral light beam portion LB is separated from the main light beam portion LA by the inclined surface portion 14B2, and the outermost light beam portion LC “outside” further passes through the cylinder lens 145 to reach the surface to be scanned, thereby forming a light spot. And may disturb the light spot shape.

  In order to effectively eliminate such a problem, as shown in FIG. 4, a slope portion 14B3 outside the rectangular portion 14A3 on the exit surface side of the cylinder lens 147, which is a surface that refracts or reflects a peripheral light beam portion. A light-shielding portion 15 for shielding a peripheral light beam portion (LA or LA and LC in FIG. 3) may be formed on a further outer portion of the light-emitting device.

  The light-shielding portion 15a of the light-shielding portion 15 is a portion for blocking emission of a light beam (the outermost light beam portion LC in FIG. 3) of the incident light beam that is not totally reflected by the slope portion 14B, and the light-shielding portion 15b is This is a part for blocking a light beam part totally reflected by the slope part 14B. Although the light-shielding portion 15b is not always necessary, it is preferable to provide the light-shielding portion 15b in order to eliminate the possibility that the peripheral light beam separated from the main light beam portion by the inclined surface portion 14B exits the cylinder lens and affects the light scanning as stray light. The light shielding portion 15 can be easily and reliably formed by printing or coating.

  By the way, the function of the conventional aperture provided in the optical scanning device is to shut off the peripheral light beam portion of the coupled light beam and to stabilize the shape and spot diameter of the light spot. As shown in FIG. 5, even if the aperture 150 is formed directly on the lens surface of the cylinder lens 148 by printing or coating, the purpose of providing the aperture can be achieved.

  However, when the aperture 150 is formed directly on the lens surface of the cylinder lens 148 by printing or the like as shown in FIG. 5, accurate alignment between the formed aperture 150 and the cylinder lens 148 is not always easy.

  Therefore, in Reference Technique 1, as shown in FIG. 6, a main light beam portion including a main light beam of a coupled light beam and forming a light spot is formed on a surface on the exit side of a cylinder lens 149 as a first imaging optical system. Is formed as a depression 141, and a peripheral light beam shielding unit 150 is formed by printing or coating in a portion around the depression 141. It is practical that the cylinder lens 149 is formed by molding with plastic, and the depression 141 can be easily and reliably formed with high accuracy with respect to the cylinder lens 149 by using a mold. If the peripheral light beam shielding unit 150 is uniformly formed by printing, the inside of the recess 141 automatically "remains without being printed", so that the formation of the peripheral light beam shielding unit 150 is easy. When the peripheral light beam shielding unit 150 is formed by coating, the recess 141 may be filled with a coating, and the coating may be removed after the coating.

  When the cylinder lens 149 having the depression 141 is formed by a mold, it is preferable that the side wall portion of the depression 141 is slightly tapered so that the mold can be easily removed. In this case, the tapered side wall portion acts as a total reflection surface for the peripheral light beam portion just outside the main light beam portion, but the peripheral light beam portion totally reflected at this portion blocks the peripheral light beam. There is no problem because the light is shielded by the unit 150.

  FIG. 9 shows an example in which the cylinder lens 145 described with reference to FIG. 3 is provided in the housing shown in FIG. FIG. 9A shows a configuration in which the cylinder lens 145 is disposed closer to the polygon mirror than the peripheral light beam shielding portion 17. The light beam coupled by the coupling lens 12 is surrounded by the peripheral light beam shielding portion 17. The outer portion of the light beam is blocked and enters the cylinder lens 145.

  Then, the main light beam portion LA passes through the cylinder lens 145, and the peripheral light beam portion LB immediately outside the main light beam portion LA is totally reflected and separated from the main light beam portion LA.

  FIG. 9B shows an embodiment in which the cylinder lens 145 is provided closer to the collimator lens 12 than the peripheral light beam shielding portion 17. When the light beam coupled by the coupling lens 12 enters the cylinder lens 145, the peripheral light beam portion LB immediately outside the main light beam portion LA is totally reflected and separated from the main light beam portion LA, and the light beam outside the peripheral light beam portion LB The outermost peripheral light beam portion LC and the main light beam portion LA pass through the cylinder lens 145. Of these, the outermost peripheral light beam portion LC is blocked by the peripheral light beam shielding portion 17. Thus, only the main beam portion LA advances to the polygon mirror side.

  In the optical scanning device of Reference Technique 2, the housing in which the optical system is provided is molded by a mold, and the aperture function of the first imaging optical system reflects or refracts light in a direction different from the main light beam portion. The light-shielding portion that shields the peripheral light beam portion may be formed integrally with the housing.

  In the embodiment of the reference technology 2 shown in FIG. 10A, in the cylinder lens 14 described with reference to FIG. 1, the light shielding portion 191 for shielding the peripheral light beam portion LB separated from the main light beam portion LA by refraction is provided with the housing. It is formed integrally. In the embodiment shown in FIG. 10B, in the cylinder lens 140 described with reference to FIG. 2, the light shielding portion 192 for shielding the peripheral light beam portion LB separated from the main light beam portion LA by total reflection is integrated with the housing. Is formed.

FIG. 2 is a diagram for explaining an optical scanning device and a first imaging optical system having an aperture function. It is a figure for explaining the 1st imaging optical system of a claim 5 and a 6th. FIG. 9 is a diagram for explaining a problem when a light beam diameter of a light beam that is coupled and enters a cylinder lens 145 is large. . FIG. 4 is a diagram for explaining the solution of the problem in the case of FIG. 3. FIG. 9 is a diagram for describing a problem with reference technology 1. FIG. 2 is a diagram for describing an embodiment of Reference Technique 1. FIG. 2 is a diagram for explaining one embodiment of the invention described in claim 1. It is a figure for explaining another embodiment of the invention of Claim 2. FIG. 6 is a diagram for explaining an embodiment of the invention described in claim 3. FIG. 9 is a diagram for describing an embodiment of Reference Technology 2.

Explanation of reference numerals

14a A cylinder lens as a first image forming optical system 17 A peripheral light beam shielding member for transmitting a main light beam portion including a principal light beam of a coupled light beam and forming a light spot and blocking a peripheral light beam portion outside the main light beam portion Part 17
20 Housing in which peripheral light shielding portion 17 is integrally formed

Claims (6)

The light beam from the light source is coupled by a coupling lens, and the coupled light beam is formed as a long line image in the main scanning corresponding direction by the first image forming optical system, and is deflected and reflected in the vicinity of the image forming position of the line image. An optical scanning device which deflects the light beam at an equal angular velocity by an optical deflector having a surface, condenses the deflected light beam as a light spot on the surface to be scanned by a second imaging optical system, and optically scans the surface to be scanned. At
A housing in which the optical system is provided is molded by a mold,
A peripheral light beam shielding portion that passes a main light beam portion forming a light spot including a main light beam of the coupled light beam and blocks a peripheral light beam portion outside the main light beam portion is formed integrally with the housing. An optical scanning device, comprising: The optical scanning device according to claim 1,
An optical scanning device, wherein the peripheral light beam shielding portion is configured by disposing a plurality of components at different positions on an optical path. The optical scanning device according to claim 1 or 2,
A first imaging optical system having an aperture function of restricting a light beam cross section of the coupled light beam;
At least one surface of the first imaging optical system passes a main light beam portion that includes a main light beam of the coupled light beam and forms a light spot, and passes a peripheral light beam portion outside the main light beam portion to the main light beam portion. An optical scanning device having a surface shape that reflects or refracts light in a direction different from that of the optical scanning device. The optical scanning device according to claim 3,
The first imaging optical system is a cylinder lens having a positive power only in the sub-scanning corresponding direction, and a periphery for refracting a peripheral light beam portion in a direction different from the main light beam portion around a portion for passing the main light beam portion. An optical scanning device having a refraction surface portion for a light beam portion. The optical scanning device according to claim 3,
The first imaging optical system is a cylinder lens having a positive power only in the sub-scanning corresponding direction, and a reflection for reflecting a peripheral light beam in a direction different from the main light beam around a portion through which the main light beam passes. An optical scanning device characterized in that a surface is formed. The optical scanning device according to claim 5,
An optical scanning device, wherein the reflection surface in the first imaging optical system is a total reflection surface.

Images