JP2000035546A - Multi-beam scanner and its light source unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce difficulty in the positional adjustment of a coupling lens and effectively reduce the influence of environmental changes in a multi-beam scanning device. SOLUTION: This multi-beam scanner is provided with plural pieces of semiconductor lasers 101, 102, plural coupling lenses 103, 104 to cope with each of the semiconductor lasers and the couple the beams from the corresponding semiconductor laser to subsequent optical systems and a holder 60 for holding the plural pieces of the semiconductor lasers and the plural coupling lenses. The holder 60 is of a one body structure having a plate-like base part 61 for fixedly holding the plural semiconductor lasers 101, 102 press-fitted at a prescribed position and a shelf-like part 62 projecting so as to almost cross perpendicularly to the plate-like base part 61; the plural coupling lenses 101, 102 are fixed on the shelf-like part 62 with an adhesive while being adjusted at the position and the plural pieces of semiconductor lasers 101, 102 are press-fitted to the holder 60 so that the direction in the package radius direction becomes the same as the holder 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multi-beam scanning device and a light source unit thereof.

[0002]

2. Description of the Related Art A plurality of beams from a plurality of light emitting units are guided to a surface to be scanned through a common optical system, and are condensed as a plurality of spots separated from each other in a sub-scanning direction. It is intended to realize a multi-beam scanning apparatus in which a plurality of beams are simultaneously deflected by a deflector and a plurality of lines are simultaneously scanned by the plurality of spots. FIG. 2A shows an example of a multi-beam scanning device. The light source device 10 emits two beams simultaneously. These two beams are both parallel light beams, are focused by the cylindrical lens 12 in the sub-scanning corresponding direction (the direction corresponding to the sub-scanning direction on the optical path from the light source to the surface to be scanned), and are rotated by an optical deflector. Each of the polygon mirrors 14 forms a long line image in the vicinity of the deflecting reflection surface in the main scanning corresponding direction (the direction corresponding to the main scanning direction on the optical path from the light source to the surface to be scanned), and is reflected by the deflecting reflection surface. Is deflected at a constant angular velocity with the constant speed rotation of the rotary polygon mirror 14, is incident on the fθ mirror 16 having an imaging function, is reflected, and is turned back by the mirror 18, so that the long toroid having a barrel-shaped toroidal surface is obtained. The light passes through the lens 20, the optical path of which is bent by the mirror 22, and the photoconductive photoconductor 24.
(Which forms the substance of the surface to be scanned). mirror 16 and long toroidal lens 20 cooperate to focus each beam as a spot on the surface to be scanned. Each beam from the light source device 10 is a parallel light beam, and is formed as a long line image in the main scanning corresponding direction on the deflection reflecting surface position of the rotary polygon mirror. The fθ mirror 16 mainly functions to form each deflected beam on the surface to be scanned in the main scanning corresponding direction and a function to make the light scanning by the spots uniform (fθ function). And The long toroidal lens 20 has a function of forming each deflected beam on the surface to be scanned in the sub-scanning corresponding direction in cooperation with the fθ mirror 16. That is, the fθ mirror 16 and the long toroidal lens 20 have a function of making the vicinity of the deflecting reflection surface and the position of the scanned surface geometrically conjugate in the sub-scanning corresponding direction. Accordingly, the multi-beam scanning device shown in FIG. 2A has a function of correcting “surface tilt” in the rotary polygon mirror 14.

FIG. 2B shows a light source device 10 shown in FIG.
Of FIG. 1 is an explanatory diagram. A beam from a semiconductor laser 101 as a light source is coupled to a subsequent optical system by a coupling lens 103, and a beam from the semiconductor laser 102 is coupled to a subsequent optical system by a coupling lens 104, and each coupled beam is a “parallel beam”. Becomes Each of the coupled beams is combined by the beam combining unit 105. The beam synthesizing unit 105 includes a half-wave plate 1051 and a prism 10.
52, and the prism 1052 has a polarization separation film 1053. The polarization splitting film 1053 transmits P-polarized light and reflects S-polarized light. Semiconductor lasers 101 and 102
From the polarization separation film 1053
It is emitted to be "polarized." Therefore, when the beam coupled by the coupling lens 103 enters the prism 1052, it passes through the polarization separation film 1053 as it is. The beam coupled by the coupling lens 104 is rotated through the polarization plane by 90 degrees by transmitting through the half-wave plate 1051, and the polarization separation film 10
53 becomes S-polarized light. This beam is applied to prism 1
The light is totally reflected by the prism surface 052, then reflected by the polarization splitting film 1053, and exits from the prism 1052. Thus, the beams from the semiconductor lasers 101 and 102 are combined. Coupling lens 103, 1
04 are parallel to each other, and the distance between these optical axes is
When the beams are combined by the beam combining means 105, the optical axes of the coupling lenses 103 and 104 are determined so as to coincide with each other.

Each beam emitted from the prism 105 is in a linearly polarized state, and the planes of polarization are at 90 degrees to each other. The “common optical system” includes a deflecting / reflecting surface of the rotary polygon mirror 14, the fθ mirror 16, and mirrors 18 and 22.
Included as reflective surface. As is well known, the reflectance of the reflecting surface changes according to the reflection angle, but the reflectance changes depending on whether the reflecting surface is S-polarized light or P-polarized light. A quarter-wave plate (common to each beam) for changing the polarization state of each combined beam to circular polarization in order to prevent variations (causing “shading” which is a variation in spot intensity) not)
Is provided inside the light source device 10 or between the light source device 10 and the cylindrical lens 12. Also, in order to make the shape of the spot condensed on the surface to be scanned an appropriate shape,
Each combined beam needs to be "beam shaped"
An aperture (not shown) for beam shaping (common to each beam) is provided inside the light source device or at an appropriate position.

As described above, the coupling lens 10
3 and 104 are arranged so that “the optical axes of these lenses match” by beam combining by the beam combining means 105, so that the light emitting units of the semiconductor lasers 101 and 102 are positioned on the optical axis of the corresponding coupling lens. If provided, the beam spots from the semiconductor lasers 101 and 102 overlap each other on the surface to be scanned. Therefore, when the light emitting portions of one or both semiconductor lasers are shifted by a small distance with respect to the optical axis of the corresponding coupling lens, the spots formed by the beams are shifted from each other on the surface to be scanned.

FIG. 2C shows the relationship between two spots SP1 and SP2 on the surface to be scanned. The horizontal direction in the figure is the “main scanning direction”, and the vertical direction is the “sub-scanning direction”. The distance between the two light-emitting units in the state of being synthesized by the beam synthesizing unit 105 is dm in the main scanning corresponding direction and ds in the sub-scanning corresponding direction, and the coupling lens, the cylindrical lens 12, the fθ mirror 16, and the long toroidal lens 2
If the combined imaging magnification of the optical system between the light emitting portion and the surface to be scanned is βm in the main scanning corresponding direction and βs in the sub-scanning corresponding direction, the spot S in FIG.
The intervals P1 and SP2 in the main scanning direction: Lm and the interval in the sub-scanning direction: Ls are respectively Lm = βm · dm and the interval in the sub-scanning direction: Ls = βs · ds. Therefore, FIG.
Returning to (a), the light source device 10 can be rotationally adjusted as a whole (with the optical axis of the coupling lens 103 as an axis), and by rotating the light source device 10 as a whole,
The separation amount Ls in the sub-scanning direction of the spots SP1 and SP2 can be adjusted. Since the separation amount: Ls is a pitch of two lines scanned at the same time, by changing this, the "writing density" in writing by multi-beam scanning can be changed. That is, when performing density switching, a "density switching signal" is input to an angle control unit (computer or the like) 26, and the angle control unit 26 controls the rotation of a motor 28 to achieve a desired density. As shown in FIG. 2B, the “write signal” is transmitted to the LD drive unit 3 via the write control unit 30 (computer or the like).
The LD drive unit 32 controls the modulation of the light emission of the semiconductor laser 101 by the write signal of the odd line, and controls the modulation of the light emission of the semiconductor laser 102 by the write signal of the even line. Prior to the start of optical scanning, each beam is detected by a not-shown synchronous light detecting means, and the timing of starting writing with each beam is determined based on the detection result. Spots SP1 and SP shown in FIG.
The separation amount Lm of 2 in the main scanning direction is set so as to separate each spot into “a size large enough to be independently detected by the same detection unit”.

FIG. 3A shows a "holder" intended for holding a semiconductor laser and a coupling lens in the light source device 10 of the multi-beam scanning device of FIG. 2 so as to be orthogonal to the plate-like base 51 of the holder 50.
The two shelves 501 and 502 are projected, and these shelves 5
01 and 502 respectively.
104 is deployed. Each semiconductor laser is press-fitted and fixed to the holes 503 and 504 formed in the base 51 from the back side of the base 51, and the beam from each light-emitting unit is applied to the holes 503 and 50.
4 and enters the coupling lenses 103 and 104. Thus, each semiconductor laser and the coupling lens 1
The holder 50 holding the holders 03 and 104 is screwed (not shown) by screw holes at four corners of the plate-like base 51 in a casing (not shown; a beam combining means is fixedly provided) of the light source device. Fixed at. Shelf-like portions 501 and 502 in the holder 50 and holes 503 for press-fitting the semiconductor laser.
The positional relationship of 504 is such that the semiconductor laser is pressed into the holes 503 and 504 in consideration of the positional relationship between the light emitting portion position of the semiconductor laser and the optical axis of the coupling lens, and the coupling lens is appropriately arranged on the shelf. Then, it is determined that the positional relationship in design is realized. As is well known, a semiconductor laser has a semiconductor laser chip mounted on a package. Referring to FIG. 4, the upper diagram of FIG.
This shows a state where the semiconductor laser is viewed from the front side of the package. The lower part of FIG. 4 (a) is a-a of the upper part of (a).
a section is shown. A semiconductor laser chip 5 is positioned and adhered to a shelf-like holding portion 2 projecting from the bottom of the package 1. This bonding is performed so that the active layer of the semiconductor laser chip is parallel to the surface of the shelf-like holding unit 2. The light emitting section 6 of the semiconductor laser 1 is located at the center of the active layer of the semiconductor laser chip 5. This light emitting portion is designed at the center position of the package 1, but is actually shifted from the center position due to an error in manufacturing, an error at the time of bonding, or the like. This “displacement” mainly occurs in a direction orthogonal to the active layer in the semiconductor laser chip 5 (a mark 7 is written on the package 1 to indicate this direction).

[0008] The position error of the light-emitting portion in the semiconductor laser (the amount of deviation from the center of the package) is about ± 50 μm, and the “variation” is uneven for each lot. Here, the “direction in the package radial direction” of the semiconductor laser is defined as follows. That is, the “direction in the package radial direction” is the same as that in the upper diagram of FIG.
The direction from the light emitting unit 6 to the shelf 2 in the direction orthogonal to the surface of the shelf-like holding unit 2 through the light emitting unit 6 is referred to. In FIG. 4A, therefore, the direction toward the right side of the drawing through the light emitting unit is the “direction in the package radial direction”.
become. Since the plane of polarization of the beam emitted from the semiconductor laser is parallel to the active layer, when the beam combining means as shown in FIG. 2 is used, the direction allowed in the package radial direction is as shown in FIG. Holder 50 like
In this case, the direction is limited to the direction orthogonal to the shelf portions 501 and 502. As described above, when a semiconductor laser having a light emitting unit whose position is shifted is held by the holder 50 of FIG. 3, the positional shift between the light emitting unit of the semiconductor laser and the optical axis of the coupling lens is caused by the position shift. Is generated. As shown in FIG. 3B, the correction of the positional deviation is performed by connecting the coupling lenses 103 and 104 to the shelves 501 and 502.
This is performed by adjusting the thicknesses of the adhesive layers 8A and 8B to be adhered to the layers: Δ1 and Δ2.

By the way, consider the case where the two semiconductor lasers 101 and 102 shown in FIG. 4B are mounted on a holder with the "directions in the package radial direction" being opposite to each other as shown in the figure. Suppose, +50 for each semiconductor laser
If there is a displacement of the light emitting portion of μm, the semiconductor laser 1
Relative shift between light emitting portions 01 and 102: Δ is 100 μm
become. In such a case, when the correction is performed by adjusting the thicknesses of the adhesive layers 8A and 8B: Δ1 and Δ2 shown in FIG. 3B, the difference between the thicknesses of the adhesive layers 8A and 8B becomes 100 μm due to the above-described reasons alone.
m. If there is such a large difference between the thicknesses of the adhesive layers 8A and 8B, "adjustment of the optical axis position" of the coupling lens becomes difficult. Also, when the temperature and humidity change while the light source unit is incorporated in the multi-beam scanning device, the relative positional relationship of the spots on the surface to be scanned changes because the amount of change in the thickness of the adhesive layer changes. However, the recorded image is adversely affected.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the trouble of adjusting the position of the coupling lens in a multi-beam scanning apparatus and to effectively reduce the influence of environmental changes.

[0011]

According to the light source unit of the present invention, "a plurality of beams from a plurality of light-emitting portions are guided to a surface to be scanned through a common optical system, and are formed as a plurality of spots separated from each other in a sub-scanning direction. A part of a light source device used in a multi-beam scanning apparatus of a system in which a plurality of beams are simultaneously deflected by an optical deflector included in the optical system and a plurality of lines are simultaneously scanned by a plurality of spots, It has a plurality of semiconductor lasers, a plurality of coupling lenses, and a holder. "Multiple semiconductor lasers"
Are used individually as light sources. Each of the “plurality of coupling lenses” corresponds to each semiconductor laser, and couples a beam from the corresponding semiconductor laser to a subsequent optical system. The coupling action may be a “collimating action” that causes the coupled beam to be a “substantially parallel light beam”, or depending on the design of the optical system, the coupled beam may have a weak divergent light flux. Or a weakly converging luminous flux. The “holder” holds a plurality of semiconductor lasers and a plurality of coupling lenses. The holder has an integrated structure having a plate-shaped base that press-fits a plurality of semiconductor lasers into predetermined positions and fixedly holds the semiconductor laser, and a shelf-shaped portion that protrudes substantially perpendicular to the plate-shaped base, A plurality of coupling lenses are fixedly mounted on the shelf while being adjusted in position by an adhesive. The plurality of semiconductor lasers are press-fitted into the holder such that “the directions in the package radial direction are the same”.

The number of semiconductor lasers held by the holder can be two (claim 2).
The above-described semiconductor laser (and three or more coupling lenses) can be held by a holder. The shelf of the holder can also hold a beam combining unit that combines the beams coupled by the coupling lenses. Various types of beam combining means can be used. By using a combination of a mirror and a semi-transparent mirror, three or more beams can be easily combined. In particular, as in the light source unit according to claim 2,
When two semiconductor lasers are held in the holder,
On the shelf of the holder, there are two coupling lenses, a prism having a reflection surface and a polarization separation film, and a half-wave plate for rotating the polarization surface of one beam by 90 degrees. Beam synthesis using polarization state of light. "
The beam combining means can be held (claim 3).

[0013] In the light source unit according to the third aspect,
The aperture and / or quarter-wave plate can be held on the shelf of the holder (claim 4). “Aperture” is for performing beam shaping on each of a plurality of beams synthesized by the beam synthesis unit. The "1/4 wavelength plate" is for converting the polarization state of a plurality of beams into circularly polarized light. The aperture and / or quarter wave plate is "common to each beam." 5. The light source unit according to claim 4, wherein each semiconductor laser is oriented in the package radial direction such that the shelf-shaped holding portion to which the semiconductor laser chip is adhered and fixed is located on the shelf-shaped side of the holder. (Claim 5). The light source unit according to any one of claims 1 to 5, wherein each of the press-fit portions of the semiconductor laser in the holder has a "cylindrical shape protruding toward the back side of the plate-like base", and a cylindrical outer periphery of each press-fit portion. A "radiating fin which also serves as a reinforcing rib" can be formed in the portion (claim 6). The multi-beam scanning apparatus according to the present invention is configured such that “a plurality of beams from a plurality of light-emitting portions are guided to a surface to be scanned via a common optical system, and are focused as a plurality of spots separated from each other in a sub-scanning direction. 7. A light source according to any one of claims 1 to 6, wherein the light deflector included in the multi-beam scanning device simultaneously deflects the plurality of beams and simultaneously scans a plurality of lines with a plurality of spots. It has a unit (claim 7).

[0014]

FIG. 1 is a diagram for explaining an embodiment of a light source unit in a multi-beam scanning device according to the present invention. In order to avoid complication, the same reference numerals as those in FIGS. FIG. 1A shows a state in which the light source unit is viewed from a direction orthogonal to a shelf-like portion of the holder. The holder 60 is a member that holds two semiconductor lasers, two coupling lenses, and a beam combining unit.
And a shelf portion 62. The plate-shaped base portion 61 is provided with mounting holes 63 and 64 for mounting a semiconductor laser. FIG. 1B shows the state of FIG. 1A viewed from the lower side of the figure. The figure is a "partial sectional view", and the hatched portion in the figure is a cross section. The mounting hole 63 (not shown, but also the mounting hole 64) penetrates the plate-like base 61, and
The reference numerals 01 and 102 are press-fitted and fixed to the mounting holes 63 and 64 from the rear side of the base. The shelf portion 62 includes a plate-like base portion 61.
And projecting so as to be substantially parallel to the arrangement direction of the semiconductor lasers 101 and 102 held at right angles to the plate-like base 61 and to be integral with the plate-like base 61.

The beam combining means 105 is “the same as that shown in FIG. 2”. As shown in FIG. 1A, a prism 105 having a reflection surface 1050 and a polarization separation film 1053 is used.
2 and 1/2 for rotating the polarization plane of one beam by 90 degrees
It has a wavelength plate 1051 and “performs beam combining using the polarization state of each beam”. In assembling the light source unit, first, as described above, the semiconductor laser 1
01 and 102 are press-fitted into the mounting holes 63 and 64, respectively. Next, a light-curable adhesive, for example, an “ultraviolet curable resin” is applied to the beam combining means provided area of the shelf portion 62,
The beam synthesizing unit 105 is provided in this portion, and the position of the semiconductor lasers 101 and 102 is adjusted. When the adjustment is completed, ultraviolet light is irradiated to cure the resin, and the beam synthesizing unit 105 is fixed to the holder 60. Next, an aperture AP and a quarter-wave plate 70 which are provided in common for each beam and perform beam shaping of each beam are provided as shown in the figure, and are fixed to the shelf 62. The aperture AP has a “rectangular opening that is long in the main-scanning corresponding direction”, and each beam is beam-shaped by passing through this opening so as to block a beam peripheral portion. Subsequently, an ultraviolet curable resin is applied to the coupling lens disposition area, and the coupling lens 10
3 and 104, adjust the position of each coupling lens in the optical axis direction (adjust so that the coupled beam becomes a parallel beam), and adjust the optical axis of each coupling lens and the semiconductor laser. The thickness of the adhesive layer is adjusted so that the positional relationship with the light emitting portion satisfies a predetermined relationship. After the adjustment is completed, each coupling lens is fixed to the shelf by irradiating ultraviolet light. When the semiconductor lasers 101 and 102 are press-fitted into the holder 60, the "directions" of the semiconductor lasers 101 and 102 are aligned such that "the directions in the package radial direction are the same" as shown in FIG. In this embodiment, the direction in the package radial direction is “downward” in FIG. 1C for both the semiconductor lasers 101 and 102, and therefore, the semiconductor laser chip 5 The shelf-shaped holding part 2 to which the adhesive is fixed is located on the side of the shelf-shaped part 62 of the holder 60.

That is, the light source unit in the multi-beam scanning device shown in FIG. 1 guides a plurality of beams from a plurality of light emitting units to a surface to be scanned via a common optical system, and separates the plurality of beams from each other in the sub-scanning direction. It is used as a light source configuration in a multi-beam scanning apparatus of a system in which light is condensed as spots, the plurality of beams are simultaneously deflected by an optical deflector included in the optical system, and a plurality of lines are simultaneously scanned by the plurality of spots. A plurality of semiconductor lasers 101 and 102, a plurality of coupling lenses 103 and 104 corresponding to each semiconductor laser, and coupling a beam from the corresponding semiconductor laser to a subsequent optical system;
It has a holder 60 for holding a plurality of semiconductor lasers and a plurality of coupling lenses, and the holder 60 is a plate-shaped base that press-fits a plurality of semiconductor lasers 101 and 102 into predetermined positions and fixedly holds them. 61, and a shelf-like portion 62 projecting substantially perpendicular to the plate-like base, and the shelf-like portion 62 includes a plurality of coupling lenses 10
3 and 104 are fixed while being adjusted in position by an adhesive, and the plurality of semiconductor lasers 101 and 102 are
0 is pressed into the holder 60 so that the package radial direction is the same (claim 1).

Further, the number of semiconductor lasers held in the holder 60 is two (claim 2), and a beam combining unit combines the beams coupled by the respective coupling lenses to the shelf 62 of the holder 60. The beam combining means 105 includes a reflecting surface 1050 and the polarization separation film 1.
And a half-wave plate 1051 for rotating the polarization plane of one of the beams by 90 degrees, and performs beam combining using the polarization state of each beam. ). As shown in FIG. 1C, the semiconductor lasers 101 and 102 are mounted on the holder 6 such that the direction of the package in the radial direction with respect to the holder 60 is the same.
Even if there is a “position shift of the light emitting portion” in each of the semiconductor lasers, most of them are generated in the same direction in the same type of semiconductor laser.
The thickness of 8B: the difference between ΔA and ΔB does not increase to several tens of μm or more. Therefore, the optical axis position of the coupling lens can be easily adjusted, and the relative positional relationship of the spots on the surface to be scanned is large even when the temperature and humidity change while the light source unit is incorporated in the multi-beam scanning device. Does not change.

The embodiment shown in FIG. 1 also performs beam shaping on each of the plurality of beams synthesized by the beam synthesizing means 105.
P and the polarization state of the plurality of beams to be circularly polarized,
A quarter-wave plate 70 common to each beam is held on the shelf 62 of the holder (claim 4). Therefore, this light source unit has a beam shaping function and a shading correction function as well as a beam combining function.

Then, each of the semiconductor lasers 101 and 102
Is such that the shelf-shaped holding section 2 to which the semiconductor laser chip 5 is adhered and fixed is positioned on the shelf-shaped section 62 side of the holder 60.
The package radial direction is determined (claim 5). In a semiconductor laser chip, heat is generated with lighting. This heat is transmitted to the holder 60 through the package.
When heat is transferred to the holder 60, a temperature distribution occurs in the shelf 62, but the upper surface (the surface on the side where the coupling lens is fixed) of the shelf 62 is closer to the heat source than the lower surface, so that the temperature is lower. When the above temperature distribution occurs, the shelf portion 62 in FIG. 1 (b) has a "warp" in which the end holding the beam combining means 62 is bent downward.
Is generated. On the other hand, the shelf-like holding unit 2 in the semiconductor laser
Generates a “warp” due to the heat transfer of the heat generated as described above, toward a surface (back surface) opposite to the bonding surface of the semiconductor laser chip 5. Contrary to the embodiment of FIG.
1, "the package radial direction" is shown in FIG.
If it is upward in (c), the direction of the warp of the shelf portion 62 due to the heat generation and the direction of the warp of the shelf holding portion 2 are opposite to each other, so that the optical axis of the light beam radiated from the semiconductor laser is The optical axis of the coupling lens and the optical axis of the coupling lens have an angle in a direction away from each other. As a result, the distance in the main scanning direction between two spots on the surface to be scanned is affected. When the package radial direction is determined so that the shelf-like holding portion 2 to which the laser chip 5 is adhered and fixed is located on the side of the shelf-like portion 62 of the holder 60, the shelf-like holding portion 2 accompanying the heat generation can be obtained. Since the warp and the warp of the shelf 62 are in the same direction, the deviation between the optical axis of the light beam emitted from the semiconductor laser and the optical axis of the coupling lens can be effectively reduced.

FIG. 1D shows a state of the back side of the holder 60. As shown in FIGS. 1A and 1B, each of the press-fit portions of the semiconductor lasers 101 and 102 in the holder 60 has a cylindrical shape protruding toward the rear surface of the plate-shaped base 61. ), The radiation fins 601 to 6 which also serve as “reinforcing ribs” are provided on the outer peripheral portion of the cylindrical shape of each press-fitting portion.
07 is formed (claim 6). By having the radiation fins 601 to 607 in this manner, the heat generated in the semiconductor laser is effectively radiated, so that the temperature rise in the semiconductor laser can be effectively reduced, and the radiation fin also serves as a reinforcing rib. Thereby, the strength required for the semiconductor laser press-fitting portion can be effectively maintained. When the temperature of the semiconductor laser rises significantly, a discontinuous change in the oscillation wavelength occurs due to so-called “wavelength jump”, and the chromatic aberration in the optical system changes the spot imaging position and the imaging shape, which affects multi-beam scanning. However, the wavelength jump can be effectively prevented by the cooling effect of the radiation fins.

Obviously, the light source unit shown in FIG. 1 can be used as a light source device in the multi-beam scanning device shown in FIG. 2 by mounting it in a suitable housing. Therefore, the light source device configured using the above-described light source unit as the light source device 10 in FIG. 2 is the first embodiment of the multi-beam scanning device according to claim 7.
Form. In the above embodiment, the beam combining means, the aperture, and the quarter-wave plate are held on the shelf of the holder, but these are separate from the holder, that is, separate from the light source unit. You can also.

[0022]

As described above, according to the present invention, a novel multi-beam scanning device and a light source unit in the multi-beam scanning device can be realized. As described above, the light source unit of the present invention includes a plurality of semiconductor lasers,
Since the package is pressed into the holder in the same radial direction with respect to the holder, the thickness of the adhesive layer with respect to each coupling lens can be maintained even if each semiconductor laser has a "position shift of the light emitting unit". The difference in height is small. Therefore, it becomes easy to adjust the optical axis position of the coupling lens,
Even if the temperature and humidity change while the light source unit is incorporated in the multi-beam scanning device, the relative positional relationship of the spots on the surface to be scanned does not change significantly. According to the fifth aspect of the present invention, the warpage of the shelf-shaped holding portion to which the semiconductor laser chip is adhered and fixed and the warpage of the shelf-shaped portion of the holder are caused in the same direction due to the heat generated by the semiconductor laser chip. The optical axis of the light beam radiated from the optical axis and the optical axis of the coupling lens do not significantly shift due to the warpage. According to the sixth aspect of the invention, the heat generated by the semiconductor laser is effectively radiated by the heat radiation fins, so that the temperature rise in the semiconductor laser can be effectively reduced, and scanning failure due to so-called “wavelength jump” is effectively prevented. Can be reduced or prevented. The multi-beam scanning device according to the present invention is hardly affected by environmental changes by using the light source device as described above, so that good multi-beam scanning can always be realized.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of a light source unit according to the present invention.

FIG. 2 is a diagram illustrating an example of a conventional multi-beam scanning device that is intended to be implemented.

FIG. 3 is a diagram illustrating a light source unit that is conventionally intended.

FIG. 4 is a diagram for explaining a problem to be solved by the invention.

[Explanation of symbols]

 101, 102 Semiconductor laser 103, 104 Coupling lens 60 Holder 61 Plate base 62 Shelf

Claims (7)

[Claims] 1. A plurality of beams from a plurality of light emitting units are guided to a surface to be scanned via a common optical system, and are focused as a plurality of spots separated from each other in a sub-scanning direction. In a multi-beam scanning apparatus of a system in which a plurality of beams are simultaneously deflected by a deflector and a plurality of lines are simultaneously scanned by the plurality of spots, a plurality of semiconductor lasers and a plurality of semiconductor lasers corresponding to the respective semiconductor lasers. A plurality of coupling lenses for coupling the beam to a subsequent optical system; a plurality of semiconductor lasers; and a holder for holding the plurality of coupling lenses. An integrated structure having a plate-shaped base that is press-fitted into a predetermined position and fixedly held therein, and a shelf-shaped portion that projects so as to be substantially perpendicular to the plate-shaped base. Thus, the plurality of coupling lenses are fixed to the shelf while being adjusted in position by an adhesive, and the plurality of semiconductor lasers have the same package radial direction with respect to the holder. A light source unit in the multi-beam scanning device, wherein the light source unit is press-fitted into the holder. 2. The light source unit according to claim 1, wherein the number of semiconductor lasers is two. 3. The light source unit according to claim 2, further comprising beam combining means for combining beams coupled by each coupling lens on a shelf of the holder, wherein said beam combining means includes a reflecting surface and A prism having a polarization splitting film, and rotating the polarization plane of one beam by 90 degrees 1
A light source unit in a multi-beam scanning device, comprising: a half-wave plate; and performing beam combining using the polarization state of each beam. 4. A light source unit according to claim 3, wherein beam shaping is performed on each of the plurality of beams synthesized by the beam synthesis means, and an aperture common to each beam and / or a polarization state of the plurality of beams. A light source unit in a multi-beam scanning apparatus, wherein a 波長 wavelength plate common to each beam, which is a circularly polarized light, is held on a shelf of the holder. 5. The light source unit according to claim 4, wherein each of the semiconductor lasers is arranged in a radial direction of the package such that the shelf-shaped holding portion to which the semiconductor laser chip is adhered and fixed is located on the shelf-shaped side of the holder. A light source unit in a multi-beam scanning device, the direction of which is determined. 6. The light source unit according to claim 1, wherein each of the press-fitting portions of the semiconductor laser in the holder has a cylindrical shape protruding toward the back side of the plate-like base portion. A light source unit in a multi-beam scanning device, wherein a radiation fin serving also as a reinforcing rib is provided on a cylindrical outer peripheral portion. 7. A plurality of beams from a plurality of light-emitting portions are guided to a surface to be scanned via a common optical system, and are focused as a plurality of spots separated from each other in a sub-scanning direction. A multi-beam scanning apparatus of a system in which a plurality of beams are simultaneously deflected by a deflector and a plurality of lines are simultaneously scanned by the plurality of spots, wherein the light source unit according to any one of claims 1 to 6 is provided. Multi-beam scanning device.