JP2001194605A - Multi-beam scanner, multi-beam scanning method, light source device, and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a plurality of deflection light beams individually by synchronous photodetecting means in the multi-beam scanning. SOLUTION: A multi-beam scanner has the synchronous photodetecting means 22 and 24 which detect the deflection light beam going to the scanning area of a surface to be scanned 20. A light source device 10 which emits a plurality of light beams has the N semiconductor lasers 1a-1c and N coupling lenses 2a-2c having the 1:1 correspondence relation to the lasers. Each of the coupiling lenses has the same configuration and the optical axes of the lenses are made in parallel to each other relating to the horizontal scanning direction. In the light receiving face position of the synchronous photodetecting means, when two arbitrary deflection light beams which are mutually adjacent are set to Bi and Bi+1(i=1 to N-1), and the deviation of the horizontal scanning direction from the optical axis of the coupling lens of the semiconductor laser light-emitting part which emits the beams Bi and Bi+1 is set to ζi and ζi+1, with respect to the lateral magnification: M (main) of the horizontal scanning direction of the optical system disposed between each semiconductor laser and light receiving face positions and the resolution: Δof the synchronous photodetecting means, the deviations: ζi and ζi+1 satisfy relation: Δ<=M (main).|ζi-ζi+1|.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a multi-beam scanning device, a multi-beam scanning method, a light source device, and an image forming device.

[0002]

2. Description of the Related Art A plurality of deflected light beams emitted from a light source device and deflected are converged toward a surface to be scanned by a common scanning and imaging optical system, and are converged on the surface to be scanned in the sub-scanning direction. A multi-beam scanning device that forms a plurality of light spots separated from each other and simultaneously scans a plurality of lines by the plurality of light spots has been proposed in the past, and from the viewpoint of increasing the efficiency of light scanning, Its realization is intended. In order to perform multi-beam scanning, a plurality of light beams are required, and the light source device needs a number of light emitting units corresponding to the number of light beams. As such a plurality of light emitting units, a semiconductor laser array can be used, or a plurality of independent semiconductor lasers can be used. The semiconductor laser array has a problem of so-called "crosstalk" in which the light emitting units arranged in the array are close to each other, so that the light emitting intensities of the adjacent light emitting units influence each other. Is difficult. When a plurality of independent semiconductor lasers are used as the light emitting section, there is no problem of crosstalk, and the light quantity control of each semiconductor laser can be performed with high accuracy. In the case of multi-beam scanning, since a plurality of lines on the surface to be scanned are scanned simultaneously, it is necessary to align the scanning start positions for each deflected light beam. To do this, the light spots formed by the plurality of deflected light beams are arranged "in one line in the sub-scanning direction", and any one of the light spots is detected by "synchronous light detecting means for starting scanning". However, a method of performing the same synchronization control for all the light spots can be considered.

In the case where a plurality of light spots are separated in the main scanning direction, the "separation amount in the main scanning direction between adjacent light spots" is determined in advance as a design condition, and the light to start scanning first is determined. The spot is detected by the synchronous light detecting means, and the start of scanning of the "light spot to start scanning first" is synchronized based on the detection signal. There is a method of sequentially generating a synchronization signal for starting scanning of a subsequent light spot by a delay time corresponding to the amount of separation in the main scanning direction from the "spot".
When "independent semiconductor lasers" are used as the light-emitting part of the light source device, the mechanical accuracy of the optical system deteriorates over time due to mechanical vibrations and environmental fluctuations, and the positional relationship between the light spots changes over time. Fluctuates to 1
In the "method of synchronizing the scanning start of another light spot on the basis of one", there is a problem that a "shift" occurs with time in the scanning start position between the light spots and the written image is degraded. Therefore, in order to avoid such a problem, a plurality of light spots are separated in the main scanning direction to separate the individual light spots as in the invention disclosed in Japanese Patent Application Laid-Open No. 8-179229. It is preferable to detect and synchronize the start of scanning individually for a plurality of light spots.

[0004]

SUMMARY OF THE INVENTION According to the present invention, in a multi-beam scanning, when a plurality of independent semiconductor lasers are used as a light emitting unit of a light source device, a plurality of deflection light beams are individually separated by a synchronous light detecting means. Detectable, novel multi-beam scanning device and multi-beam scanning method, novel light source device used in the multi-beam scanning device,
It is an object to realize a novel image forming apparatus using the above multi-beam scanning device.

[0005]

A multi-beam scanning apparatus according to the present invention basically includes a method of "collecting a plurality of deflected light beams emitted from a light source device and deflected toward a surface to be scanned by a scanning image forming optical system. A multi-beam scanning device that forms a plurality of light spots on the surface to be scanned that are separated from each other in the sub-scanning direction, and simultaneously scans a plurality of lines with the plurality of light spots. In order to synchronize the start of scanning, there is provided a "synchronous light detecting means for detecting a deflected light beam directed to the scanning area on the surface to be scanned". The “scanning optical system” for converging a plurality of deflected light beams toward the surface to be scanned and forming a light spot may be constituted by one lens or two or more lenses. Alternatively, a configuration including one or more lenses and “one or more mirrors having an imaging function” may be employed. As described above, the synchronous light detecting means detects the deflected light beam directed to the scanning area on the surface to be scanned. Therefore, the synchronous light detecting means has a "light receiving means", and receives the deflected light beam by the light receiving means to generate a light receiving signal. The light receiving surface of the light receiving means is provided, for example, at a position "equivalent to the surface to be scanned and capable of receiving a light beam traveling toward the scanning area". The position equivalent to the scanned surface is “a position where the light beam received on the light receiving surface is substantially condensed on the light receiving surface at least in the main scanning direction”.
It is.

For example, if a light receiving surface is arranged at a position equivalent to the above-mentioned scanned surface and a "light beam having passed through the scanning image forming optical system" is made incident on the light receiving surface, the scanned surface is not placed on the light receiving surface. A light spot similar to that described above is formed. Scanning optical systems often include `` a long toroidal lens with substantially no power in the main scanning direction, A cylindrical lens. In such a case, since the long toroidal lens or the cylindrical lens does not have substantial power in the main scanning direction, the light spot is generated in the scanning imaging optical system in the main scanning direction. The part excluding the lens ”is formed. In such a case, the light receiving surface of the synchronous light detecting means is placed at a position equivalent to the surface to be scanned, and the scanning image forming optical system receives the "deflected light beam that has passed through the portion excluding the toroidal lens and the cylindrical lens". When light is received by the surface, what is formed on the light receiving surface is “an elliptical spot having a width equivalent to the light spot in the main scanning direction and a long shape in the sub-scanning direction”. Even a spot is enough to be used as synchronization light. In this case, a cylindrical lens may be arranged near the light receiving surface to focus the light beam on the light receiving surface even in the sub-scanning direction. Of course, the light beam deflected toward the scanning area is focused on the light receiving surface of the light receiving means of the synchronous light detecting means by a dedicated optical system without passing through the scanning image forming optical system. ".

The multi-beam scanning device according to the first aspect has the following features. That is, a light source device that emits a plurality of light beams has at least N (≧ 2) semiconductor lasers and N coupling lenses corresponding to each of these semiconductor lasers in a 1: 1 correspondence. The N coupling lenses have the same configuration, and the optical axis is made parallel to the main scanning direction. That is, the optical axes of the N coupling lenses are parallel to each other when viewed from the sub-scanning direction. At the position of the light receiving surface of the synchronous light detecting means, any two deflected light beams adjacent to each other are converted to B _i ,
B _{i + 1} (i = 1 to N−1). These beams B _i , B
The light emitting portion of the semiconductor laser emitting _{i + 1} shifts in the main scanning direction from the optical axis of the corresponding coupling lens:
It is shifted by ζ _i , ず ら_{i + 1} . When the lateral magnification in the main scanning direction of the optical system disposed between each semiconductor laser and the light receiving surface position is M (main), the resolution of the synchronous light detecting means is as follows:
With respect to Δ, the deviation amounts: ζ _i and Δ _{i + 1} are set so as to satisfy Δ ≦ M (main) · | ζ _i −ζ _{i + 1} | Individually detectable. Above displacement: ζ
“0” may be included in _i , ζ _{i + 1} (i = 1 to N−1). "Resolution of synchronization detection means:
Δ ”is a“ light receiving surface ”required for the two polarized light beams because the synchronous light detecting means“ can separate and detect two polarized light beams adjacent in the main scanning direction as separate light beams ”. Upper limit of the amount of separation in the main scanning direction ”. This resolution is about 0.5 mm for a photo sensor which is a typical light receiving means.

According to a second aspect of the present invention, there is provided a multi-beam scanning apparatus.
It has the following features. That is, a light source device that emits a plurality of light beams includes a first light source unit, a second light source unit, and a beam combining unit. The “first light source unit” includes n (≧ 2) semiconductor lasers, n coupling lenses corresponding to each of these semiconductor lasers, and n semiconductor lasers and n cups. The ring lens has a holding body that holds the n coupling lenses with the optical axes of the n coupling lenses parallel to each other in the main scanning direction and integrally holds the ring lenses in a predetermined positional relationship. The “second light source unit” includes m (≧ 2) semiconductor lasers, m coupling lenses corresponding to each of these semiconductor lasers, and m semiconductor lasers and m cups. The ring lens includes a holding member that holds the m coupling lenses with their optical axes parallel to each other in the main scanning direction and integrally holds the ring lenses in a predetermined positional relationship. The “beam combining unit” is a unit that combines the n light beams emitted from the first light source unit and the m light beams emitted from the second light source unit as light beams that are close to each other. A shift amount of a light emitting portion of an arbitrary semiconductor laser in the first light source portion from the optical axis of the corresponding coupling lens in the main scanning direction: ζ _i (i = 1 to n);
The amount of deviation of the light emitting portion of an arbitrary semiconductor laser in the second light source portion from the optical axis of the corresponding coupling lens in the main scanning direction: ζ _k (k = 1 to m), and the first and second light source portions. The positional relationship of the beam synthesizing means is set such that "the deflected light beams adjacent to each other are separated from each other in the main scanning direction by the above-mentioned resolution: Δ or more at the light receiving surface position of the synchronous light detecting means". The light beams can be individually detected by the synchronous light detecting means.

In the multi-beam scanning device according to the second aspect, n = m and the first light source unit and the second light source unit can have the same structure (claim 3). Each semiconductor laser in the first and second light source units is press-fitted and fixed in a holding hole of a corresponding holder, and each coupling lens ゛ is fixed to the corresponding holder with an adhesive resin. Adjusting the position of the optical axis of the laser with respect to the light-emitting portion. " In this case, n = m = 2 (claim 5). As the “adhesive resin”, for example, an “ultraviolet curable resin” can be used. As in the fourth aspect of the present invention, when an adhesive resin is used to fix the coupling lens to the holder, and the position of the optical axis with respect to the light emitting portion of the semiconductor laser is adjusted by the adhesive resin (amount of the adhesive resin), Since the volume of the resin changes due to "fluctuations in temperature and humidity", the relative relationship between the light emitting section and the optical axis of the coupling lens fluctuates due to environmental changes. In such a case, if only one light spot is detected by the synchronous light detecting means, and the synchronization of the scanning start positions of the other light spots is fixedly controlled with reference to this light spot, the above-described “inter-light spot However, in the present invention, since the light beams are individually detected by the synchronous light detecting means, an appropriate timing of the scanning start is given for each light beam. be able to.

The multi-beam scanning device according to claim 6 is
It has the following features. That is, a light source device that emits a plurality of light beams has at least N (≧ 2) semiconductor lasers and N coupling lenses that correspond to each of these semiconductor lasers in a 1: 1 correspondence. The N coupling lenses have the same configuration, and the optical axes are not parallel to each other in the main scanning direction. In the light-receiving surface position of the synchronous light detection means, when any two deflected light beams which are adjacent to each other B _i, B _{i + 1} and (i = 1~N-1), the beams B _i, B _{i + 1} corner optical axis of the coupling lenses corresponding to the semiconductor laser emitting forms the main scanning direction: phi _i, the beam B _i, the interval in the main scanning direction B i _{+ 1} is the resolution of the synchronization light detecting means: delta The setting is made as described above. Therefore, each polarized light beam can be individually detected by the synchronous light detecting means. The multi-beam scanning device according to the seventh aspect has the following features. That is, a light source device that emits a plurality of light beams includes a first light source unit, a second light source unit, and a beam combining unit. The “first light source unit” includes n (≧ 2) semiconductor lasers, n coupling lenses corresponding to each of the semiconductor lasers, and n semiconductor lasers and n couplings. A holding member that holds the lenses integrally so as to maintain a predetermined positional relationship such that the optical axes of the n coupling lenses form a predetermined angle in the main scanning direction.

The “second light source section” includes m (≧ 2) semiconductor lasers, m coupling lenses corresponding to each of these semiconductor lasers, and m semiconductor lasers and m laser diodes. And a holder for integrally holding the coupling lenses in a predetermined positional relationship such that the optical axes of the m coupling lenses form a predetermined angle in the main scanning direction. The “beam combining unit” is a unit that combines n light beams emitted from the first light source unit and m light beams emitted from the second light source unit as light beams that are close to each other. Then, the optical axis direction of each coupling lens in the first and second light source sections, and the mutual positional relationship between the first and second light source sections and the beam combining means are such that the mutually adjacent deflected light beams are in the main scanning direction. The resolution is set so as to be separated by a distance of Δ or more. Therefore,
Each polarized light beam can be individually detected by the synchronous light detecting means. In the multi-beam scanning device according to the seventh aspect, n = m, and the first light source unit and the second light source unit can have the same configuration (claim 8). In the multi-beam scanning device according to the eighth aspect, the light emitting units of the respective semiconductor lasers in the light source device can be arranged on the optical axis of the corresponding coupling lens (claim 9). Also,
9. The multi-beam scanning device according to claim 8, wherein n = m.
= 2 (claim 10). In the multi-beam scanning device according to the sixth aspect, N (≧ 2)
At least P (2 ≦ P ≦ N) of the semiconductor lasers
The light emitting units can be arranged so as to be shifted from the optical axis of the corresponding coupling lens in the main scanning direction.
1). In the multi-beam scanning device according to claim 7, at least P (2) out of n + m semiconductor lasers.
≦ P ≦ n + m) light emitting units can be arranged so as to be shifted from the optical axis of the corresponding coupling lens in the main scanning direction. In this case, n = m, and the first light source unit and the second light source unit can have the same configuration. In the multi-beam scanning device according to the thirteenth aspect, n = m = 2 (claim 14).

According to a fifteenth aspect of the present invention, in the multibeam scanning apparatus according to any one of the first to fourteenth aspects, the plurality of light beams emitted from the light source device are the same as those of the optical deflector. And a light source device is configured so that the plurality of light beams cross in the main scanning direction in the vicinity of the deflecting reflection surface. A multi-beam scanning device according to a sixteenth aspect is the multi-beam scanning device according to any one of the first to fifteenth aspects, wherein the plurality of light beams radiated from the light source device are identically deflected by the optical deflector. It is configured to be deflected simultaneously on the surface, and between the light source device and the optical deflector, a plurality of light beams from the light source device,
In the vicinity of the deflecting / reflecting surface, there is a line image forming optical system that forms an image as a “long line image in the main scanning direction” separated from each other in the sub-scanning direction. It is characterized in that the surface to be scanned is anamorphic in a geometrical conjugate relationship in the sub-scanning direction. With such a configuration of the multi-beam scanning device, it is possible to correct the tilt of the deflecting reflection surface. The "light source device" of the present invention is a light source device used in a multi-beam scanning device, and has a configuration described in any one of the first to sixteenth aspects (claim 17). "Multi-beam scanning method" of the present invention
A plurality of deflected light beams emitted from a light source device and deflected are condensed toward a surface to be scanned by a scanning image forming optical system, and a plurality of light beams separated in the sub-scanning direction are formed on the surface to be scanned. This is a multi-beam scanning method in which spots are formed and a plurality of lines are simultaneously scanned by the plurality of light spots.

A multi-beam scanning method according to the eighteenth aspect is performed using the multi-beam scanning device according to any one of the first to fifteenth aspects. The multi-beam scanning method according to the nineteenth aspect provides the multi-beam scanning method according to the sixteenth aspect.
The method is performed by using the multi-beam scanning device described above. The image forming apparatus of the present invention is an “image forming apparatus that forms a latent image on a latent image carrier by optical scanning and visualizes the latent image to obtain a desired recorded image”. An image forming apparatus according to claim 20, wherein the multi-beam scanning device according to any one of claims 1 to 15 is used as an optical scanning device for optically scanning the latent image carrier. The image forming apparatus described above uses the multi-beam scanning device according to claim 16 as an optical scanning device that optically scans a latent image carrier. 22. The image forming apparatus according to claim 20, wherein the latent image carrier is a photoconductive photoconductor, and an electrostatic latent image is formed by uniform charging and optical scanning.
The formed electrostatic latent image can be configured to be visualized as a toner image. The toner image is fixed on a sheet-like recording medium (transfer paper or a plastic sheet for an overhead projector). In the image forming apparatus according to the present invention, for example, a silver halide photographic film can be used as the photosensitive medium. In this case, the latent image formed by optical scanning by the multi-beam scanning device can be visualized by a normal silver halide photographic process. Such an image forming apparatus can be implemented as, for example, an “optical plate making apparatus”. The image forming apparatus according to claim 22 is, specifically, a laser printer or a laser plotter,
It can be implemented as a digital copying machine, a facsimile machine, or the like. As explained above, in a multi-beam scanning device,
The plurality of light spots must be separated from each other on the surface to be scanned in the sub-scanning direction. Various methods are available for separating a plurality of light spots on the surface to be scanned in the sub-scanning direction. When the light source device includes a plurality of semiconductor lasers and a plurality of coupling lenses corresponding to the semiconductor lasers in a 1: 1 manner as in each of the multi-beam scanning devices described above, for example, the optical axis of the coupling lens In contrast, the light-emitting portion of the corresponding semiconductor laser is shifted in the sub-scanning direction, and the “shift amount of the light-emitting portion in the sub-scanning direction with respect to the optical axis of the coupling lens” is adjusted for each pair of the semiconductor laser and the coupling lens. By
The light spots may be separated from each other in the sub-scanning direction, or the optical axes of the individual coupling lenses may form a small angle with each other in the sub-scanning direction, and the angles formed by the respective optical axes in the sub-scanning direction. By adjusting, the light spots can be separated from each other in the sub-scanning direction, or the direction of the optical axis and the “shift amount in the sub-scanning direction from the optical axis of the light emitting unit” can be adjusted. Accordingly, the light spots may be separated from each other in the sub-scanning direction.

The coupling function of the coupling lens in the above description may be a function of converting a divergent light beam from the light emitting portion of the corresponding semiconductor laser into a parallel beam, or a divergent or convergent light beam. May be used.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1A, three light beams are emitted from a light source device denoted by reference numeral 10 (in order to avoid complication of the drawing, light beams emitted from the light source device 10). Only one of them). The emitted light beams (which are substantially parallel beams) are incident on a cylindrical lens 12 as a line image forming optical system. The cylindrical lens 12 has a positive power only in the sub-scanning direction, focuses the three incident light beams only in the sub-scanning direction, and closes the light beam near the deflecting and reflecting surface of the rotary polygon mirror 14 as an optical deflector. , As a long line image in the main scanning direction. A line image is formed for each light beam, and the line images are separated from each other in the sub-scanning direction. When the rotating polygon mirror 14 is rotated at a constant speed in the direction of the arrow by a motor (not shown), the three light beams reflected by the deflecting / reflecting surface are respectively deflected as deflected light beams and deflected at a constant angular velocity. Each deflected light beam is incident on an fθ lens 16 as a scanning image forming optical system while being deflected, and when transmitted through the fθ lens 16, is reflected by a folding mirror 18 which is a long flat mirror, the optical path is bent, and the surface to be scanned is scanned. The light is condensed as a light spot on the peripheral surface of the photoreceptor 20 which is an entity of the above by the action of the fθ lens 16. The three light spots formed on the surface to be scanned are separated from each other in the sub-scanning direction, and simultaneously scan three lines on the surface to be scanned at a time as shown in the figure. The plane mirror 22 is arranged near the “scan-start-side end” of the folding mirror 18 in the longitudinal direction. The portion where the plane mirror 22 is disposed is outside the effective deflection area necessary for the deflected light beam to scan the effective scanning area on the surface to be scanned. The deflected light beam reflected by the plane mirror 22 is a photosensor 2 serving as a light receiving means for detecting synchronous light.
4 is incident. That is, each deflected light beam is first deflected to the scanning area of the surface to be scanned,
2 and is reflected, and then enters the photosensor 24 and is received. The light receiving surface of the photo sensor 24 is arranged at “a position optically equivalent to the surface to be scanned”. Since each deflected light beam incident on the plane mirror 22 is subjected to the optical action of the fθ lens 16, each deflected light beam is condensed on the light receiving surface of the photo sensor 24 as a light spot similar to that on the surface to be scanned. In this embodiment, the plane mirror 22 and the photo sensor 24 constitute "synchronous light detecting means".
The light receiving area on the light receiving surface of the photo sensor 24 has a size having a resolution: Δ (for example, 0.5 mm) in the main scanning direction.

FIG. 1B is an explanatory diagram showing a main part of the light source device 10 in FIG. 1A. The main part of the light source device 10 includes three semiconductor lasers 1a, 1b, 1
c, and coupling lenses 2a, 2b, and 2c corresponding to these semiconductor lasers on a 1: 1 basis. These semiconductor lasers 1a-1c and coupling lenses 2a-2c
Are defined in a mutual positional relationship, and are integrally held by appropriate holding means (not shown). The semiconductor lasers 1a to 1c and the coupling lenses 2a to 2c have the same configuration, and are each arranged substantially in the main scanning direction. Also, the coupling lenses 2a to 2c
The divergent luminous flux from each of the light emitting units of the corresponding semiconductor lasers 1a to 1c is converted into a “substantial parallel beam”. That is,
The light emitting portion of each semiconductor laser is located substantially on the focal plane of the corresponding coupling lens. FIG. 1 (c)
A state where the coupling lenses 2a to 2c are arranged in the main scanning direction is shown. A “+” mark drawn at the center of each coupling lens indicates an optical axis position. Each optical axis of the coupling lenses 2a to 2c is parallel to each other, and FIG.
(C) is a direction orthogonal to the drawing. The code Ha,
Hb and Hc represent light emitting portions of the semiconductor lasers 1a, 1b and 1c corresponding to the coupling lenses 2a, 2b and 2c, respectively. The light emitting portion Hb is a coupling lens 2b
Is located on the optical axis of. On the other hand, the light emitting section Ha has “ζa” in the main scanning direction from the optical axis of the coupling lens 1a,
It is shifted by “Δa” in the sub-scanning direction. Similarly, the light emitting unit Hc is shifted from the optical axis of the coupling lens 1c by “Δc” in the main scanning direction and by “Δc” in the sub-scanning direction. Such a positional relationship between the light emitting unit and the optical axis is set with high precision using a jig. FIG. 1D shows the light emitting units Ha, Hb,
The behavior of the principal ray of the light beam emitted from Hc is shown.
Since the light emitting unit Hb is located on (the focal position of) the optical axis of the coupling lens 2b, the light beam emitted from the light emitting unit Hb is converted into a parallel beam by the coupling lens 2b,
The chief ray travels along the optical axis of the coupling lens 2b. On the other hand, the light emitting units Ha and Hc are displaced from the optical axes of the corresponding coupling lenses 2a and 2c.
The light beams from these light emitting units are converted into parallel beams by the corresponding coupling lenses, but the direction of the principal ray is refracted by the coupling lenses as shown by the solid line in the figure. For this reason, the direction of the principal ray of the light beam converted into a parallel beam by the coupling lenses 2a and 2c is inclined with respect to the optical axis of the coupling lenses 2a and 2c.

The three light beams emitted from the light source device 10 form a light spot on the surface to be scanned and on the light receiving surface of the photo sensor 24 as described above. FIG. 1 (e)
FIG. 4 shows the state of a light spot on the light receiving surface of the photo sensor 24 as an explanatory diagram. The state of the light spot formed on the surface to be scanned is the same. FIG. 1 (e)
, “Light spots” denoted by reference signs Sa, Sb, Sc
Are formed by light beams emitted from the semiconductor lasers 1a, 1b, and 1c, respectively. Optically, these light spots Sa, Sb, Sc are coupled to the coupling lenses 2a, 2b, 2c and the cylindrical lenses 12, f.
9 is an image of the light-emitting portions Ha, Hb, and Hc by the θ lens 16. Each light spot is formed into an "elliptical shape" slightly longer in the sub-scanning direction by adjusting the "size of the aperture" of the beam shaping aperture disposed at an appropriate position between the light source and the optical deflector. Have been. As shown in FIG. 1E, with respect to the light spot Sb, the light spot Sa is shifted by “δab” in the main scanning direction and “ηa” in the sub-scanning direction.
b, the light spot Sc shifts by “δb
c ”and“ ηbc ”in the sub-scanning direction. Considering a “synthetic optical system” of the coupling lenses 2 a to 2 c (these are optically equivalent as described above), the cylindrical lens 12, and the fθ lens 16, the synthetic optical system is in the main scanning direction. And an anamorphic optical system having different powers in the sub-scanning direction and in the sub-scanning direction.
(Sub), the above-mentioned δab, δbc, ηab, ηb
c is given by δab = M (main) ζa, δbc = M (main) ζc ηab = M (sub) 副 a, ηbc = M (sub) ξ 副 c, respectively. Since ηab and ηbc are scanning line intervals between two adjacent lines scanned at the same time, “ηab = ηb
c ”, ie, |「 a | = | ξc |, the “shift amount in the sub-scanning direction with respect to the optical axis of the coupling lens” of the light emitting units Ha and Hc is set.

On the other hand, for δab and δbc, the light spot formed by each deflected light beam on the light receiving surface of the photosensor 24 needs to be separately detected by the photosensor 24. Photo sensor 2
4 must be larger than the resolution in the main scanning direction: Δ. That is, by defining ζa and ζc so as to satisfy Δ ≦ δab and Δ ≦ δbc, the light spots of the three deflected light beams can be detected separately by the same photo sensor 24. Based on the detection result, the start position of scanning by each deflected light beam can be controlled independently, and the start position can be "aligned to the same position" with high accuracy for each deflected light beam. Note that ζa, ζ
c may be ξa = ξc or ζa ≠ ζc as long as “Δ ≦ δab and Δ ≦ δbc” are satisfied. Since the combining optical system is an afocal system in the main scanning direction, the lateral magnification in the main scanning direction is
Assuming that the focal length of the coupling lenses 2a to 2c is f and the focal length of the fθ lens 16 in the main scanning direction is F, M
(Main) = F / f. In the embodiment described above, the amount of deviation of the light emitting portion Hb of the semiconductor laser 1b from the optical axis of the coupling lens 2b in the main scanning direction: ζ
Although b is 0, ０b may be a finite value other than 0. When ζb ≠ 0, Δ ≦ F / f | ζa−ζb | and Δ ≦ F / f | ζc−
What is necessary is just to set ζa, よ い b, ζc so that ζb | Note that in this case, ζa, ζb, and ζc correspond to FIG.
In the above, the case where it is on the right side of the optical axis is positive, and the case where it is on the left side is negative.

In the embodiment described above, the light source device 10
A plurality of deflected light beams emitted from and deflected by the scanning imaging optical system 16 toward the surface to be scanned 20;
In a multi-beam scanning apparatus that forms a plurality of light spots separated from each other in the sub-scanning direction on the surface to be scanned 20 and simultaneously scans a plurality of lines with the plurality of light spots, synchronization of the scanning start by each deflected light beam is synchronized. For this purpose, the light source device 10 having synchronous light detecting means 22 and 24 for detecting a deflected light beam directed to the scanning area of the surface to be scanned and emitting a plurality of light beams is composed of N (= 3) semiconductor lasers. 1a to 1c, and at least N coupling lenses 2a to 2c corresponding to each of the semiconductor lasers in a 1: 1 ratio. The N coupling lenses 2a to 2c have the same configuration, and have a main scanning direction. The light axes from the corresponding semiconductor lasers are made substantially parallel beams, and are adjacent to each other at the light receiving surface position of the synchronous light detecting means. Any two deflected light beam B that
_i , B _{i + 1} (i = 1 to 2), and these beams B _i , B _{i + 1}
ず れ_i , ζ _{i + 1 in the} main scanning direction from the optical axis of the corresponding coupling lens of the light emitting portion of the semiconductor laser emitting
(Ζaζζc), the lateral magnification in the main scanning direction of the optical system arranged between each semiconductor laser and the light receiving surface position: M
(Main) and the resolution: Δ of the synchronous light detection means, the shift amounts: ζ _i , ζ _{i + 1} , and the relationship: Δ ≦ M (Main) · | ζ _i -ζ _{i + 1}
Is set so as to satisfy |, so that each deflected light beam can be individually detected by the synchronous light detecting means. In the above embodiment, the coupling lenses 2a to 2a
Although the optical axes of c are parallel to each other, they are parallel to each other only in the main scanning direction (that is, parallel to each other when viewed from the sub-scanning direction), and the optical axes are minute in the sub-scanning direction. In this case, even if the amount of deviation is set to ξa = ξb = ξc = 0, the light spot is moved in the sub-scanning direction by adjusting the minute angle formed by the optical axis. Can be separated.

FIGS. 2 and 3 are views for explaining another embodiment of the light source device usable as the light source device of the multi-beam scanning device shown in FIG. 1A. In addition, in order to avoid complication, the same reference numerals are used throughout FIG.
FIG. 2A is a diagram for explaining a structure of a main part of the light source device. Reference numerals 1a, 1b, 1c, and 1d indicate semiconductor lasers, and reference numerals 2a, 2b, 2c, and 2d indicate "coupling lenses corresponding to each of the semiconductor lasers 1a, 1b, 1c, and 1d." Reference numerals 3A and 3B denote holders, and reference numeral 4 denotes a prism as beam combining means. Semiconductor lasers 1a, 1b, 1c, 1d
Have the same configuration, and the coupling lenses 2a, 2
b, 2c, and 2d have the same configuration. Each coupling lens is set to convert a light beam from the corresponding semiconductor laser into a parallel beam. In addition, the holders 3A, 3B
Have the same configuration. Holder 3A and semiconductor laser 1
a, 1b and the coupling lenses 2a, 2b
Light source unit ". The holder 3B, the semiconductor lasers 1c and 1d, and the coupling lenses 2c and 2d constitute a "second light source unit". Since the first and second light source units have the “similar configuration”, the first light source unit will be described as an example. FIG. 2B is a view of the holding body 3A of the first light source unit viewed from the front side. FIG.
(C). As shown in FIGS. 2B and 2C, the base 300 of the holder 3A is plate-shaped, and a convex portion 301 for holding a lens is formed at a central portion thereof. Are formed so as to sandwich the protrusion 301. The through holes 302 and 303 penetrate the base 300 in the thickness direction and are “parallel to each other”. The diameters of the through holes 302 and 303 near the outlet on the back side of the base 300 are enlarged, and the semiconductor lasers 1a and 1b are press-fitted and fixed in these portions (FIG. 2C). Therefore, the positions of the light emitting portions of the semiconductor lasers 1a and 1b are set in the through holes 302 and 3 respectively.
03 is uniquely determined.

Further, coupling lenses 2a and 2b are fixedly provided on the convex portion 301 with the optical axes parallel to each other so as to sandwich the convex portion 301. In addition, FIG.
In (c), reference numerals 304 and 305 indicate fixing screw holes. The second light source unit connects the semiconductor lasers 1c and 1d and the coupling lenses 2c and 2d (see FIG.
Like the light source unit, the light source unit is fixedly held on the holder 3B. The first light source unit and the second light source unit are arranged so that the optical axes of the respective coupling lenses are parallel to each other and face the incident side surface of the prism 4. FIG.
Referring to (a), this figure is a diagram for explaining the state of attachment of the coupling lens to the holder, taking the state of attachment of the coupling lens 2b to the holder 3A as an example. As shown in the figure, the side surface of the convex portion 301 is formed as a concave cylindrical surface, and this cylindrical surface is coupled to the coupling lens 2b.
Mounting reference plane. Coupling lens 2
As for b, the ultraviolet curable resin 310 is applied to the edge portion, and the ultraviolet curable resin 310 is brought into contact with the cylindrical surface portion. The coupling lens 2b has a positional relationship (a shift amount in the main scanning direction: Δb) between the optical axis (represented by a “+” mark) and a light emitting portion Hb (a fixed position fixed to the holder 3A) of the semiconductor laser 1b. , The deviation amount in the sub-scanning direction: Δb) and the position in the optical axis direction are adjusted by a jig (not shown).
With the position adjusted in this way, the ultraviolet curable resin 31
When the resin is hardened by irradiating ultraviolet rays to 0, the coupling lens 2b is fixedly adhered to the convex portion 301. "Holding to the corresponding holding body" of the other coupling lenses 2a, 2c, 2d is performed in the same manner. FIG. 3B is a diagram for explaining the state of beam combining by the prism 4 with respect to the light beams emitted from the light emitting units Ha and Hc. The prism 4 has a side surface shape as shown in FIG.
The prism 4 has a configuration in which a parallelogram prism and a right-angle prism are combined, and a polarization reflection film 401 is formed at a joint between the two prisms. A half-wave plate 4 is provided at a portion where the light beam from the light emitting portion Hc is incident (not shown, but also where the light beam from the light emitting portion Hd is incident).
03 is provided.

The position of the light source is determined so that the light emitted from the light emitting portions Ha and Hb becomes P-polarized light with respect to the polarization reflection film 401. Therefore, the light beam emitted from the light emitting unit Ha and converted into a parallel beam by the coupling lens 2a (not shown, but also the light beam emitted from the light emitting unit Hb and converted into a parallel beam by the coupling lens 2b) is When the light enters the prism 4, the polarization reflection film 4 is formed.
01 through the prism 4. On the other hand, a light beam emitted from the light emitting unit Hc and converted into a parallel beam by the coupling lens 2c (not shown, but the light emitting unit Hc
The light beam radiated from d and converted into a parallel beam by the coupling lens 2 d) passes through the Ｓ wavelength plate 403, and becomes S-polarized light with respect to the polarization reflection film 401. Then, the light is totally reflected by the prism surface 402 of the prism 4 and further totally reflected by the polarization reflection film 401,
Incident from In this way, the four light beams (all of which are parallel beams) emitted from the prism 4 are combined as light beams that are close to each other. Note that two of the four light beams emitted from the prism 4 are S-polarized light, and the other two are P-polarized light, and the polarization planes are orthogonal to each other. As is well known, the reflectivity of the reflecting surface changes differently between the S-polarized light and the P-polarized light with the change in the incident angle. Therefore, if "as is", the four light beams emitted from the light source device are When the light is reflected by the deflecting / reflecting surface of the rotary polygon mirror 14, the turning mirror 18, or the like in FIG. 1A, the light intensity of the light spot on the surface to be scanned varies for every two light beams due to a change in reflectance. In order to avoid such a problem, the beam synthesized by the prism 4 is
It is preferable that the four light beams are made into a “circularly polarized state” by passing the light beams through a を wavelength plate. FIG. 3C illustrates a state where the light source device 10 is viewed obliquely from behind. The prism 4 is accommodated in a box-shaped casing indicated by the reference numeral 5 while being adjusted to a predetermined position, and the rear side plate of the casing 5 is provided with the semiconductor lasers 1a and 1a.
b, a holder 3A in which the coupling lenses 2a and 2b (not shown) are integrated, and a holder 3B in which the semiconductor lasers 1c and 1d and the coupling lenses 2c and 2d (not shown) are integrated. The holder projection (to which the coupling lens is fixed) is fitted into an engagement hole formed in the rear side plate, and the mounting position is adjusted and fixed. The four combined light beams (parallel beams) are emitted from a cylindrical emission port 5A formed in the casing 5. The exit port 5A is provided with the above-mentioned "1/4 wavelength plate" and an aperture for beam shaping. Therefore, all four parallel light beams emitted from the light source device 10 are beam-shaped and circularly polarized.

As shown in FIG. 1A, the four light beams radiated from the light source device 10 are
2 forms a "long line image in the main scanning direction" separated from each other in the sub-scanning direction in the vicinity of the deflecting and reflecting surface of the rotary polygon mirror 14, and is converted into a deflected light beam by the rotary polygon mirror. Thereby, a light spot separated in the sub-scanning direction is formed on the surface to be scanned, which is the peripheral surface of the photoconductor 20. Then, four lines (four scanning lines) on the surface to be scanned are simultaneously scanned by these four light spots. FIG. 4A is an explanatory diagram showing a combined state of the prism 4. Prism 4
When the prism 4 is viewed from the combining side, the center between the optical axes of the coupling lenses 2a and 2b and the center between the optical axes of the coupling lenses 2c and 2d match as a position q shown in FIG. Shall be performed.
In order to avoid complication of the drawing, the coupling lens 2a and the coupling lens 2c are drawn on top of each other, and the coupling lens 2b and the coupling lens 2d are drawn on top of each other. Since the optical axes of the coupling lenses are parallel to each other, and the coupling action is to convert the light beam from the semiconductor laser into a parallel beam, each coupling as long as the center between the optical axes coincides with the position: q. The position of the lens may be anywhere, and therefore, the generality of the following description is not lost even if two coupling lenses are drawn one on top of the other as shown in FIG. The semiconductor laser 1a, relative to the optical axis (indicated by a “+” mark) of the coupling lenses 2a, 2c,
The shift amounts of the light emitting portions Ha and Hc of 1c are ζa and ζc in the main scanning direction and ξa and ξc in the sub-scanning direction.
Similarly, the optical axes (“+”) of the coupling lenses 2b and 2d
Relative shift amounts of the light emitting portions Hb and Hd of the semiconductor lasers 1b and 1d with respect to the main scanning direction.
d, ξb and ξd with respect to the sub-scanning direction. At this time,
3 | ζa | = | ζc |, 3 | ζb | = | ζd |
When | ξa | = | ξc | and 3 | ξb | = | ξd |, the states of the light spots Sa, Sb, Sc, and Sd formed on the scanned surface (similarly, the light receiving surface of the photosensor 24) are set. Is as shown in FIG. “Q” is an image of the position: q by the cylindrical lens 12 and the fθ lens 16.

Assuming that the “interval in the main scanning direction” between adjacent light spots is δab, δac, δbd as shown in FIG.
These are expressed as follows using the above-described imaging magnification: M (main) (= F / f). δab = M (main) | ζb−ζa | δac = M (main) | ζc−ζa | δbd = M (main) | ζd−ζb | In order for the light spot to be separately detected by the photosensor 24, the three conditions of δab ≦ Δ, δac ≦ Δ, and δbd ≦ Δ may be independently satisfied. In other words, the shift amounts: ζa, ζc, ζb, and ζd may be set according to the imaging magnification: M (main) so that the above condition is satisfied. Shift amount in the sub-scanning direction: ξa, ξb, ξ
c and ξd are set according to the imaging magnification in the sub-scanning direction: M (sub) so that the adjacent intervals of the light spots Sa, Sb, Sc, and Sd in the sub-scanning direction match a predetermined scanning line pitch. I do. FIG. 4C shows the light emitting units Hb and H in FIG.
This is the case where the position with d is exchanged. At this time, the arrangement of the light spots Sa, Sb, Sc, and Sd on the surface to be scanned is as shown in FIG. That is, the arrangement of the light spots Sa, Sb, Sc, and Sd can be appropriately adjusted by adjusting the positional relationship between the light emitting unit and the optical axis of the coupling lens. In the case of the light spot arrangement shown in FIG. 4D, the conditions under which each light spot can be individually detected by the photosensor 24 are δad ≦ Δ, δac ≦ Δ, δbd ≦ Δ, in light of the above description. It will be easily understood.

The light source device 10 in the multi-beam scanning device shown in FIG. 1A using "the light source device described in the embodiment shown in FIGS. 2 to 4" is emitted from the light source device 10 and simultaneously deflected. The plurality of deflected light beams are condensed toward the surface to be scanned 20 by the scanning and imaging optical system 16 to form a plurality of light spots separated from each other in the sub-scanning direction on the surface to be scanned. By the light spot of
In a multi-beam scanning apparatus for simultaneously scanning a plurality of lines, there are synchronous light detecting means 22 and 24 for detecting a deflecting light beam directed to a scanning area on a surface to be scanned in order to synchronize for starting scanning with each deflecting light beam. The light source device 10 that emits a plurality of light beams includes n (= 2) semiconductor lasers 1a and 1b, and each of these semiconductor lasers has a 1: 1 ratio.
N coupling lenses 2a, 2b corresponding to
Semiconductor lasers and n coupling lenses, n
A first light source unit having a holder 3A for holding the optical axes of the coupling lenses parallel to each other with respect to the main scanning direction and integrally holding them in a predetermined positional relationship, and m (= 2)
Semiconductor lasers 1c and 1d, and m coupling lenses 2 corresponding to each of the semiconductor lasers 1: 1
c, 2d, the m semiconductor lasers and the m coupling lenses, and the optical axes of the m coupling lenses are integrally held while maintaining the predetermined positional relationship with the optical axes of the m coupling lenses being parallel to each other. A second light source unit having a holding body 3B, and n (= 2) light beams emitted from the first light source unit 3A, and m (= 2) light beams emitted from the second light source unit And a beam synthesizing means 4 for synthesizing the light beams as light beams close to each other, and a shift amount of a light emitting portion of an arbitrary semiconductor laser in the first light source portion from an optical axis of a corresponding coupling lens in a main scanning direction: ζ _i (ζa, ζb) and the second
The amount of deviation of the light emitting portion of an arbitrary semiconductor laser in the light source portion from the optical axis of the corresponding coupling lens in the main scanning direction: ζ _k (ζc, ζd), the first and second light source portions, and the beam combining means 4 Is set such that, at the light receiving surface position of the synchronous light detecting means, the deflected light beams adjacent to each other are separated in the main scanning direction by a distance equal to or more than the resolution of the synchronous light detecting means: Δ. This is a multi-beam scanning device configured so that the deflected light beams can be individually detected by the synchronous light detecting means.

In the light source device described with reference to FIGS. 2 to 4, n = m, the first light source unit and the second light source unit have the same structure (claim 3). Each semiconductor laser in the first and second light source units is press-fitted and fixed in a holding hole of a corresponding holding body, and each coupling lens 固定 is fixed to the corresponding holding body with an adhesive resin (see FIG. 3), and is bonded with an adhesive resin. The position of the optical axis of the corresponding semiconductor laser with respect to the light emitting portion is adjusted (claim 4), and n = m = 2 (claim 5). In the above-described embodiment, the optical axes of the coupling lenses 2a to 2d are parallel to each other. However, these optical axes are parallel to each other in the "main scanning direction" and form a small angle with each other in the sub-scanning direction. You may do so. As described above, when the optical axis of each coupling lens forms a small angle with respect to the sub-scanning direction, the shift amount Δa to Δd of each light emitting unit in the sub-scanning direction can be set to “0”. .
Further, it is easy to extend the embodiment described in FIGS. 2 to 4 to the case where the number of semiconductor lasers and coupling lenses: n and m is 3 or more. In the embodiment described with reference to FIGS. 1 to 4, for example, the coupling lens 2a,
Although the direction of the displacement of the light emitting units Ha and Hb with respect to the optical axis of 2b has been described as “the direction away from each other”, the “direction of the displacement”
Is not limited to such a “direction away from each other”. With reference to FIG. 5, a case where the light emitting portions Ha and Hb are displaced from the optical axes of the coupling lenses 2a and 2b will be described as an example. The light emitting portions Ha and Hb are arranged as shown in FIG. May be shifted from each other so as to approach the main scanning direction. In this case, the principal rays of the light beams that have been converted into parallel beams by the coupling lenses 2a and 2b travel away from each other in the main scanning direction. Further, as shown in FIG. 5B, the light emitting units Ha and Hb may be shifted in the “same direction”. In this case, the shift amount in the main scanning direction: ζa,
Depending on the magnitude relationship of ζb, the traveling directions of the coupled light beams can either cross each other or move away from each other in the main scanning direction.

In each of the embodiments described above, the relationship between the coupling optical axes is basically parallel to each other with respect to the main scanning direction, and the light emitting portion of the semiconductor laser is aligned with the optical axis of the corresponding coupling lens. On the other hand, it is located at a position shifted in the main scanning direction. In this case, when the number of deflected light beams used for simultaneous scanning increases, a part of the light emitting unit is arranged at a position "far away" from the optical axis of the coupling lens. Since the light flux from such a light emitting unit passes through the periphery of the corresponding coupling lens,
The wavefront aberration in the coupled light beam increases. When such wavefront aberration increases to some extent, the light beam increases the spot diameter of a light spot formed on the surface to be scanned. If an image is written on such a light spot, the image quality of the written image may not be able to achieve the desired quality. As a measure for avoiding such a problem, it can be considered that the directions of the optical axes of the coupling lenses are not parallel to each other in the main scanning direction. FIG. 6 conceptually shows one example of such a light source device. The main part of the light source device 10A includes two semiconductor lasers 1a and 1b, and coupling lenses 2a and 2b corresponding to the two semiconductor lasers 1a and 1b. The figure shows a state in which the light source device 10A is viewed from the sub-scanning direction. As shown, the optical axes of the coupling lenses 2a and 2b are "non-parallel with respect to the main scanning direction". The optical axes are in the same plane in the sub-scanning direction. The light emitting portions of the semiconductor lasers 1a and 1b are Ha and Hb as before, and the shift amounts of the light emitting portions from the optical axes of the coupling lenses 2a and 2b are Δa and Δb in the main scanning direction and Δa and Δb in the sub-scanning direction. Then, ζa = ζb = 0, and ξa and ξb are determined so that the light spot on the surface to be scanned is separated by the scanning line pitch in the sub-scanning direction. In this case, it is not necessary to dispose the light-emitting portion largely away from the optical axis of the coupling lens, and the above-described problem of wavefront aberration degradation can be effectively avoided (even if the number of semiconductor lasers and coupling lenses increases, the same applies). Is).

When such a light source device is used as a light source device of a multi-beam scanning device as shown in FIG. 1A, light spots are individually formed on a light receiving surface of a photo sensor 24 equivalent to a surface to be scanned. The conditions that can be detected are described below. In FIG. 7, reference numeral 16 denotes “FIG.
Lens 16 "shown in FIG. As shown in the figure, when a light beam having a convergence angle: φ is incident on the fθ lens 16 in the main scanning direction (up and down direction in the figure), the incident light beam has a convergence angle of “ γφ ”and forms an image at point P in the figure. Then, on the surface to be scanned 20 distant from the image forming point P by a distance: S, the area spreads by “δ” in the main scanning direction. The above “γ” is called an angular magnification of the fθ lens 16 in the main scanning direction. The angular magnification γ is uniquely determined according to the fθ lens 16. Here, the convergence angle: φ in FIG. 7 is considered to be the “angle formed in the main scanning direction” between the principal rays of the two light beams emitted from the light source device 10A shown in FIG. Then, the principal rays of the two light beams intersect at the point P, but each light beam (deflected light beam) forms an image at the position of the surface to be scanned 20. Therefore, the two light spots formed by imaging on the surface to be scanned are separated by a distance: δ in the main scanning direction. The distance: δ can be expressed as δ = 2S · tan (γφ / 2) using the angle: γφ and the distance: S in FIG. Therefore, the condition under which the two light spots can be detected individually is the resolution of the photo sensor 24: Δ
In contrast, Δ ≦ δ = 2S · tan (γφ / 2) holds. The manner of use of the fθ lens 16 is determined as a design condition, and the angular magnification γ is also determined as a characteristic of the fθ lens 16. When the angle φ is determined, the position of the point P, that is, the distance S is determined. Therefore, the angle φ should be set so as to satisfy the above condition “Δ ≦ δ = 2S · tan (γφ / 2)”. The above description can be easily extended even when the number of light beams is three or more.

That is, a light source device for emitting a plurality of light beams
Are N (≧ 3) semiconductor lasers and these semiconductor lasers.
N coupling wrens that correspond 1: 1 to each individual user
And at least N coupling lenses have
With the same configuration, the optical axes are not parallel to each other in the main scanning direction
In the case of the above, the light receiving surface of the synchronous light detecting means
In position, any two polarized light beams adjacent to each other
B_i, B_{i + 1}(I = 1 to N-1), these
Beam B_i, B_{i + 1}Power for semiconductor lasers that emit
Angle between the optical axis of the coupling lens and the main scanning direction: φ_iTo
"Beam B_i, B _{i + 1}The interval in the main scanning direction of the
Step resolution: Δ or more ”.
(Claim 6). For example, light emitted from a light source device
The number of beams is four, and these beams are₁~ B_Four
At the light receiving surface position of the synchronous light detecting means,
Assuming that the light beams B are sequentially adjacent,₁, B_TwoIs leading
Angle in inspection direction: φ₁₂And incident on the fθ lens,
And the light beam B_Two, B_ThreeIs the angle in the main scanning direction: φ_{twenty three}Doing
light beam B incident on the fθ lens_Three, B_FourIs in the main scanning direction
Angle: φ₃₄And then enter the fθ lens.
Light beam B₁, B_TwoFrom the position where the chief rays cross
The distance to the surface is S₁₂, Light beam B_Two, B_ThreeChief rays intersect
The distance from the position to_{twenty three}, Light beam B_Three,
B_FourThe distance from the position where the chief rays intersect to the light receiving surface is S
₃₄Can be used to detect each light spot individually.
To solve this problem, for the resolution of the synchronous light detection means: Δ, Δ ≦ 2S₁₂・ Tan (γφ₁₂/ 2) Δ ≦ 2S_{twenty three}・ Tan (γφ_{twenty three}/ 2) Δ ≦ 2S₃₄・ Tan (γφ₃₄/ 2) The light source device may be configured to satisfy the following condition. Each semi
Optical axis of the coupling lens that the light emitting part of the body laser corresponds to
Is not shifted in the main scanning direction (ζ = 0)
The optical axis of each coupling lens in the main scanning direction.
Angle is the above angle: φ ₁₂, Φ_{twenty three}, Φ₃₄Set to be
Good.

FIG. 8 shows a specific example of the light source device as shown in FIG. The holder denoted by reference numeral 30 has two through holes 302 ′, 30 ′ at an angle to each other in the thickness direction.
3 'is drilled, and the semiconductor lasers 1a and 1a are provided at the ends of the through holes.
b is press-fitted and fixed. Coupling lenses 2a and 2b corresponding to the respective semiconductor lasers 1a and 1b are bonded and fixed to the protrusion protruding from the center of the holder 30 in the same manner as described with reference to FIG. ing. However, in this example, the position of each coupling lens is adjusted such that each light emitting unit of the semiconductor laser is located on the optical axis of the corresponding coupling lens. The optical axes of the coupling lenses 2a and 2b are not parallel to each other in the main scanning direction as shown in the drawing, and the light spots formed by the respective light beams are separated on the surface to be scanned in the sub-scanning direction. To
In the sub-scanning direction, they form a small angle (instead of doing so, the two optical axes are on the same plane parallel to the main scanning direction, and the light-emitting portion of the semiconductor laser corresponding to each coupling lens is The position may be displaced from the optical axis position in the sub-scanning direction). Thus, two light beams that are not parallel to each other in the main scanning direction are obtained. Each coupling lens is optically identical, and converts a divergent light beam from the light emitting unit into a parallel beam. The optical device as shown in FIG. 8 uses two similar devices, and these are configured as a light source device similar to that described with reference to FIG. 2 together with the above-described prism 4 as first and second light source units. , Two light beams from the first and second light source units can be combined by the prism 4 and emitted as four parallel light beams close to each other. FIG. 9 is a diagram for explaining such a light source device. In FIG. 9, reference numeral 3C denotes the light source shown in FIG. 8, which is the first light source unit. Sign 3D
Indicates a second light source unit having the same configuration as the first light source unit 3C.
The first light source unit 3C, the second light source unit 3D is, as shown, are spaced apart by "L" in the main scanning direction, the light beam B _1, B ₃ emitted from the first light source unit 3C, the second The light beams B ₂ and B ₄ emitted from the light source unit 3D are combined so as to be alternately arranged in the main scanning direction (not shown in FIG. 9, but in order to do so, the first light source unit 3C And the second light source unit 3D, in a plane parallel to the plane of FIG. 9, the “straight line that divides the optical axis of the two coupling lenses into two equal parts” in each light source unit forms an angle with each other There). These four light beams are combined by a prism (not shown) (beam combining means similar to the prism 4 shown in FIG. 2).

These light beams B₁, B_Two, B_Three, B_FourBut
On the scanning surface (and on the light receiving surface of the synchronous light detecting means),
As shown in the figure on the right, light spots with the same
To S ₁, S_Two, S_Three, S_FourIf these are formed, these
The conditions for individually detecting light spots are as shown in FIG.
Angle the beam makes in the main scanning direction: φ₁₂, Φ_{twenty three}, Φ ₃₄
Is the angular magnification of the fθ lens: γ, the disassembly of the synchronous light detecting means
Function: Δ, with respect to the above condition: Δ ≦ 2S₁₂・ Tan (γφ₁₂/ 2) Δ ≦ 2S_{twenty three}・ Tan (γφ_{twenty three}/ 2) Δ ≦ 2S₃₄・ Tan (γφ₃₄/ 2) is satisfied, and the light source device is configured as described above.
This makes it possible to detect four light beams individually.
it can. The light source device described with reference to FIG.
Used as the light source device 10 of the multi-beam scanning device shown in FIG.
By doing so, the scanned surface that is the peripheral surface of the photoconductor 20 is
It is possible to scan four lines at a time. That is, like this
Multi-beam scanning device emits light from the light source device 10.
A plurality of deflected light beams deflected by the scanning and imaging optical system 1
6 converges toward the surface to be scanned 20 and
Form multiple light spots separated from each other in the sub-scanning direction.
And multiple lines are simultaneously formed by these multiple light spots.
In a multi-beam scanning device that scans each beam,
To be synchronized to start scanning by the
Photodetection to detect the deflected light beam heading to the scanning area
Light having emission means 22 and 24 and emitting a plurality of light beams
The source device is composed of n (= 2) semiconductor lasers and these semiconductor lasers.
N couplings corresponding to each of the body lasers 1: 1
Lens, n semiconductor lasers and n couplings
The main scanning of the lens is performed by the optical axis of the n coupling lenses.
At predetermined angles in the directions,
And a holding body that holds the body integrally while maintaining the positional relationship.
One light source unit 3C, m (= 2) semiconductor lasers, and
Cups corresponding to each of the semiconductor lasers 1: 1
Ring lens, m semiconductor lasers and m cups
The optical axis of the m coupling lenses is
At a predetermined angle in the main scanning direction,
And a holder that is held integrally in a predetermined positional relationship.
Is emitted from the second light source unit 3D and the first light source unit 3C.
n light beams and m light beams emitted from the second light source unit 3D
To combine two light beams as light beams close to each other.
In the first and second light source units.
Optical axis direction of each coupling lens, first and second light source units
And the beam synthesizing means
The deflected light beams are synchronized with each other in the main scanning direction.
Step resolution: Set to separate by a distance of Δ or more,
Direction light beam can be detected individually by synchronous light detection means
(Claim 7).

Further, when n = m, the first light source unit 3C and the second light source unit 3D have the same configuration (claim 8), and the light emitting unit of each semiconductor laser in the light source device has the optical axis of the corresponding coupling lens. (Claim 9), and n = m =
2 (claim 10). In the light source device used in the invention described in claim 6, at least P (2 ≦ P ≦ N) light emitting units of the N (≧ 2) semiconductor lasers are generally connected to the corresponding coupling lens. Can be shifted from the optical axis in the main scanning direction.
1). Similarly, in the light source device described with reference to FIG. 9, at least P (2
.Ltoreq.P.ltoreq.n + m) light-emitting portions can be arranged so as to be shifted in the main scanning direction from the optical axis of the corresponding coupling lens (claim 12). The first light source unit and the second light source unit may be configured to have the same configuration (claim 13), and n = m = 2. By arranging the light emitting portion of the semiconductor laser in the main scanning direction from the optical axis of the corresponding coupling lens, the direction of the main beam of the parallelized light beam is changed from the optical axis direction of the coupling lens to the main scanning direction. it is possible to divert the direction, angle (the angular: phi _23, etc.) which the light beam cross forms the main scanning direction can be easily adjusted. Incidentally, in each of the light source devices described above, it is preferable that all the light beams emitted from the semiconductor laser intersect in the main scanning direction in the vicinity of the deflecting and reflecting surface of the rotary polygon mirror 14. This will be described with reference to FIG. In FIG. 10, the vertical direction is the main scanning direction. In FIG. 10A, for example, the light emitting units Ha and H
The light beams from b are incident on the deflecting / reflecting surface 14A of the rotating polygon mirror while spreading out from each other. Considering the point G in the main scanning direction on the surface to be scanned 20 assuming that the rotation direction of the rotary polygon mirror is the direction of the arrow, when the light spot of the light beam from the light emitting section Ha is located at the point G, it is deflected and reflected. The surface 14A is at the position indicated by the solid line, and the light beam reaches the point G through the optical path indicated by the solid line. On the other hand, the light beam from the light emitting portion Hb is G
At the time when a light spot is formed at a point, the deflection reflecting surface 14A
Has rotated to the position shown by the broken line, and the light beam reaches the point G through the optical path shown by the broken line. As you can see from this figure,
If the positions at which the light beams from the light emitting units Ha and Hb are incident on the deflecting / reflecting surface 14 are far apart, the two light beams pass through “substantially different optical paths” and pass through different positions of the fθ lens 16. Fθ for each light beam imaged at a point
The optical action of the lens 16 is not the same. For this reason, the two light beams reaching the same image height in the main scanning direction on the surface to be scanned 20 have different optical characteristics such as aberrations, causing the scanning line to bend. There is a risk of causing fluctuation.

On the other hand, as shown in FIG.
If the light beams from the light emitting units Ha and Hb are made to cross in the main scanning direction in the vicinity of the deflecting reflection surface 14A, the light beams (deflection light beams) heading for the same image height on the surface to be scanned 20 will be substantially formed. Therefore, the scanning line is not bent as described above, and the problem of "variation in scanning line pitch between image heights" is not caused. In addition, by making all the light beams from the light source device intersect in the main scanning direction near the deflecting / reflecting surface, the radius of the inscribed circle of the rotating polygon mirror 14 can be reduced, and the rotating polygon mirror can be rotated at high speed. So,
This is advantageous for speeding up scanning. In the multi-beam scanning device according to the fifteenth aspect, in the multi-beam scanning device according to the various embodiments described above, a plurality of light beams emitted from the light source device are simultaneously deflected by the same deflective reflection surface of the optical deflector. The light source device is configured so that a plurality of light beams cross in the main scanning direction in the vicinity of the deflecting / reflecting surface. If the light source device used in such a multi-beam scanning device is realized by, for example, the light source device shown in FIG.
φ _12, φ _23, by adjusting the phi _34, the light beam B _1, B _2, B
_3, B ₄ may be to intersect in the main scanning direction by the deflecting reflection surface near. In order to realize the light source device as described with reference to FIG. 2, as shown in FIG.
3B (simplified) is separated by a distance L in the main scanning direction (vertical direction in the figure), and the light beams Ba and Bb emitted from the light emitting units Ha and Hb and the light beams Hc and Hd emitted from the light emitting units Hc and Hd. The light beams Bc and Bd can be arranged alternately in the main scanning direction, and can cross each other near the deflecting reflection surface 14A. FIG. 11B shows an example of the positional relationship between the coupling lenses 2a, 2b, 2c, and 2d and the relationship between the light-emitting portions Ha, Hb, Hc, and Hd. Since the same members are used as the coupling lenses and the holders 3A and 3B for holding the semiconductor laser, the light emitting section H
The distance between a and Hb; the distance between Aab and the distance between the light emitting portions Hc and Hd, Acc, is the same. The relative positional relationship between each light emitting unit and the optical axis of the corresponding coupling lens is appropriately set when the coupling lens is bonded and fixed.

In the example shown in FIG. 11B, a holder 3B holding the coupling lenses 2c and 2d is inclined in the longitudinal direction with respect to a holder 3A holding the coupling lenses 2a and 2b. FIG.
FIG. 3B shows a state in which the arrangement of the light emitting units as shown in FIG.
Reference numeral 2 denotes a synthesized virtual coupling lens. At this time, the light beams emitted from the light emitting units Ha, Hb, Hc, Hd form four light spots Sa, Sb, S formed on the surface to be scanned (and on the light receiving surface of the synchronous light detecting means).
The state of c and Sd is shown in FIG. In the multi-beam scanning device of FIG. 1A using each of the light source devices described above as the light source device 10, a plurality of light beams emitted from the light source device 10 are simultaneously emitted on the same deflecting and reflecting surface of the optical deflector 14. Between the light source device 10 and the optical deflector 14, a plurality of light beams from the light source device are placed near the deflecting / reflecting surface, and are separated from each other in the sub-scanning direction by long lines in the main scanning direction. The scanning image forming optical system 16 has a line image forming optical system 12 for forming an image as an image, and the scanning image forming optical system 16 has an anamorphic anamorphic relationship in which the position of the deflecting reflection surface and the position of the surface to be scanned are geometrically conjugated in the sub-scanning direction. (Claim 16). The light source device described variously is a light source device used for a multi-beam scanning device, and has a configuration described in any one of claims 1 to 16 (claim 1).
7). As described in the above embodiment, by using the multi-beam scanning device, a plurality of deflected light beams emitted from the light source device and deflected are condensed toward the surface to be scanned by the scanning imaging optical system. On the surface to be scanned, a plurality of light spots separated from each other in the sub-scanning direction are formed, and a multi-beam scanning method of simultaneously scanning a plurality of lines by the plurality of light spots can be realized.

[0035]

EXAMPLE As a specific example, a specific example of the embodiment described with reference to FIG. 1 will be described. Focal length of each coupling lens in the light source device 10: f = 27 m
m, f The focal length of the fθ lens 16 in the main scanning direction: F = 22
5.3 mm. Therefore, the above-described imaging magnification in the main scanning direction: M (main) (= F / f) = 8.34 times. At this time, the light spots Sa, Sb, Sc shown in FIG.
Are individually detectable, assuming that the resolution of the photosensor 24 is Δ = 0.5 mm and Δ ≦ δab = M (main) · ζa, Δ using δab and δbc in FIG.
.Ltoreq..delta.bc = M (main) .multidot.c. M (main) = 8.34
Considering the magnification, the shift amounts of the light-emitting portions Ha and Hc with respect to the optical axis of the coupling lens in the main scanning direction: Δa and Δc are respectively Δa = Δc ≧ 0.06 mm (= 0.5 / 8.3).
4) is good.

FIG. 12 shows an embodiment of the image forming apparatus of the present invention. The photoconductive photoreceptor 20 as a latent image carrier is formed in a cylindrical shape, rotates at a constant speed in the direction of the arrow, and uses a charging means (a contact type using a charging roller, but a corona discharge type). ), And an electrostatic latent image is formed by writing by the optical scanning of the multi-beam scanning device 114. This electrostatic latent image is
The toner image developed by the developing means 116 and obtained by the development is transferred to a transfer means (transfer / separation charger type, but may be a roller type).
Is transferred onto a sheet-like recording medium (transfer paper, plastic sheet for overhead projector, etc.) S.
The recording medium S fixes the transferred toner image to the fixing unit 122.
And is discharged out of the apparatus. After the transfer of the toner image, the cleaning device 124 removes residual toner and paper dust from the photoconductor 20. As the multi-beam scanning device 114, the above-described embodiments have been described.
Those described in any one of 16 are used. That is, FIG.
The image forming apparatus shown in FIG. 2 forms a latent image on the latent image carrier 20 by optical scanning, and visualizes the latent image to obtain a desired recorded image. As the device, a multi-beam scanning device according to claims 1 to 15 or claim 16 is used (claim 2).
0, 21), the latent image carrier 20 is a photoconductive photoconductor, and an electrostatic latent image is formed by uniform charging and optical scanning, and the formed electrostatic latent image is visualized as a toner image. (Claim 22).

[0037]

As described above, according to the present invention, a novel multi-beam scanning device, multi-beam scanning method, light source device, and image forming device can be realized. In the multi-beam scanning apparatus and the multi-beam scanning method according to the present invention, a plurality of deflected light beams heading for the scanning area for simultaneously scanning the surface to be scanned can be individually detected by the synchronous light detecting means. Since it is possible to set independently for each deflected light beam and to align the writing start position of an image written by simultaneous scanning with respect to all deflected light beams, extremely good image writing can be realized. Also,
The light source device according to the present invention separates a plurality of deflected light beams that are simultaneously scanned in the main scanning direction so that they can be individually detected on the way to the scanning region. Can be. Further, since the image forming apparatus of the present invention performs image writing using the multi-beam scanning device, high-speed and good image formation is possible. Further, the first and second light source units used in the light source device have the same structure as in the multi-beam scanning device according to claims 3 to 5, 8, and 10, so that the light source device can be shared by parts. Cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of a multi-beam scanning device according to the present invention.

FIG. 2 is a diagram for explaining an embodiment of the light source device of the present invention.

FIG. 3 is a diagram for explaining the optical device according to the embodiment shown in FIG. 2;

FIG. 4 is a diagram for explaining an example of a light spot forming state when the light source device shown in FIGS. 2 and 3 is used.

FIG. 5 is a diagram for explaining another example of the positional relationship between the light emitting unit and the coupling lens in the light source device shown in FIGS.

FIG. 6 is a view for explaining an embodiment of a light source device according to the invention described in claim 6;

FIG. 7 is a diagram for explaining conditions for individual detection of each light beam in the invention described in claim 6;

FIG. 8 is a view for explaining a specific example of the light source device according to the invention of claim 6;

FIG. 9 is a diagram for explaining an example of a light source device that combines two light source devices of FIG. 8 and performs beam combining by a prism that is a beam combining unit.

FIG. 10 is a diagram for explaining an advantage of the invention described in claim 15;

FIG. 11 is a view for explaining an example of a light source device in the multi-beam scanning device according to claim 15;

FIG. 12 is a diagram for describing one embodiment of an image forming apparatus.

[Explanation of symbols]

 1a, 1b, 1c Semiconductor lasers 2a, 2b, 2c Coupling lens 10 Light source device 12 Cylindrical lens (linear image forming optical system) 14 Rotating polygon mirror (optical deflector) 16 fθ lens (scanning optical system) 20 Photosensitivity Body (actually the scanned surface) 22 Plane mirror 24 Photosensor

Continued on front page F term (reference) 2H045 AA01 BA02 BA22 BA33 CA67 CA88 CB24 DA02 5C072 AA03 BA02 BA04 HA02 HA06 HA08 HA13 HB08 HB11

Claims (22)

[Claims] A plurality of deflected light beams emitted from a light source device and deflected are converged toward a surface to be scanned by a scanning image forming optical system, and are separated from each other in the sub-scanning direction on the surface to be scanned. In a multi-beam scanning apparatus that forms a plurality of light spots and scans a plurality of lines simultaneously with the plurality of light spots, in order to synchronize the start of scanning with each deflected light beam, a deflection toward a scanning area on a surface to be scanned is performed. A light source device that emits a plurality of light beams and has N (≧ 2) semiconductor lasers and N light sources corresponding to each of the semiconductor lasers in a 1: 1 correspondence At least a coupling lens, wherein the N coupling lenses have the same configuration, the optical axes are parallel to each other with respect to the main scanning direction, and at the light receiving surface position of the synchronous light detecting means, Any two deflected light beam B _i adjacent to each _{other, B i + 1 (i =} 1~
N−1), and the shift amounts of the light emitting portions of the semiconductor lasers emitting these beams B _i , B _{i + 1} in the main scanning direction from the optical axis of the corresponding coupling lens are ζ _i , ζ _{i + 1} . When the optical system disposed between each semiconductor laser and the light receiving surface position has a shift amount with respect to the lateral magnification M (main) in the main scanning direction and the resolution Δ of the synchronous light detecting means, : Ζ _i , ζ
_{i + 1} is set so as to satisfy the relationship: Δ ≦ M (main) · | ζ _i −ζ _{i + 1} |, so that the respective polarized light beams are individually detected by the synchronous light detecting means. A multi-beam scanning device characterized in that it is configured to be capable of scanning. 2. A plurality of deflected light beams emitted from a light source device and simultaneously deflected are converged toward a surface to be scanned by a scanning image forming optical system, and are converged on the surface to be scanned in the sub-scanning direction. In a multi-beam scanning device that forms a plurality of separated light spots and scans a plurality of lines at the same time with the plurality of light spots, in order to synchronize the start of scanning with each deflected light beam, the scanning area of the surface to be scanned is A light source device for radiating a plurality of light beams, comprising: n (≧ 2) semiconductor lasers; and n corresponding to each of these semiconductor lasers in a one-to-one correspondence. Coupling lenses,
A holding body that holds the n semiconductor lasers and the n coupling lenses such that the optical axes of the n coupling lenses are parallel to each other with respect to the main scanning direction, and that they are integrally held while maintaining a predetermined positional relationship; A first light source unit having: (m) (m> 2) semiconductor lasers; and m coupling lenses corresponding to each of these semiconductor lasers in a 1: 1 relationship;
A holding body that holds the m semiconductor lasers and the m coupling lenses so that the optical axes of the m coupling lenses are parallel to each other with respect to the main scanning direction, and is integrally held while maintaining a predetermined positional relationship; Beam combining for combining n light beams emitted from the first light source unit and m light beams emitted from the second light source unit as light beams close to each other. And a shift amount of a light-emitting portion of an arbitrary semiconductor laser in the first light source portion from the optical axis of a corresponding coupling lens in the main scanning direction: ζ _i (i = 1 to n); The amount of deviation of the light emitting portion of an arbitrary semiconductor laser in the second light source portion from the optical axis of the corresponding coupling lens in the main scanning direction: ζ _k (k = 1 to m), and the first and second light source portions And the positional relationship of the beam combining means At the light receiving surface position of the light detection means, the deflection light beams adjacent to each other are set so as to be separated in the main scanning direction by a distance equal to or more than the resolution of the synchronous light detection means: Δ or more. A multi-beam scanning device characterized in that it can be individually detected by synchronous light detecting means. 3. The multi-beam scanning device according to claim 2, wherein n = m and the first light source unit and the second light source unit have the same structure. 4. The multi-beam scanning device according to claim 3, wherein each of the semiconductor lasers in the first and second light source sections of the light source device is press-fitted and fixed in a holding hole of a corresponding holding body. A multi-beam scanning device, which is fixed to a corresponding holder with an adhesive resin, and the position of the optical axis with respect to the light emitting portion of the corresponding semiconductor laser is adjusted by the adhesive resin. 5. The multi-beam scanning device according to claim 4, wherein n = m = 2. 6. A plurality of deflected light beams emitted from a light source device and deflected by a scanning image forming optical system toward a surface to be scanned, and are separated from each other in the sub-scanning direction on the surface to be scanned. In a multi-beam scanning apparatus that forms a plurality of light spots and scans a plurality of lines simultaneously with the plurality of light spots, in order to synchronize the start of scanning with each deflected light beam, a deflection toward a scanning area on a surface to be scanned is performed. A light source device having synchronous light detecting means for detecting a light beam and emitting a plurality of light beams is composed of N (≧ 2) semiconductor lasers and N number of lasers corresponding to each of these semiconductor lasers in a 1: 1 relationship. At least a coupling lens, wherein the N coupling lenses have the same configuration, the optical axes are not parallel to each other in the main scanning direction, and Any two deflected light beam B _i adjacent to each _{other, B i + 1 (i =} 1~N-
When a 1), the angular optical axes of the beams B _i, the coupling lens corresponding to the semiconductor laser emitting a B i _{+ 1} forms the main scanning direction: the phi _i, the beam B _i, B i _{+ 1} Are set so as to be equal to or more than the resolution of the synchronous light detecting means: Δ, and the respective polarized light beams can be individually detected by the synchronous light detecting means. Multi-beam scanning device. 7. A plurality of deflected light beams emitted from a light source device and deflected are converged toward a surface to be scanned by a scanning imaging optical system, and are separated from each other in the sub-scanning direction on the surface to be scanned. In a multi-beam scanning apparatus that forms a plurality of light spots and scans a plurality of lines simultaneously with the plurality of light spots, in order to synchronize the start of scanning with each deflected light beam, a deflection toward a scanning area on a surface to be scanned is performed. A light source device for emitting a plurality of light beams, the light source device comprising: n (≧ 2) semiconductor lasers; and n light sources corresponding to each of the semiconductor lasers in a 1: 1 correspondence A coupling lens,
The n semiconductor lasers and the n coupling lenses are integrally formed while maintaining a predetermined positional relationship such that the optical axes of the n coupling lenses form a predetermined angle in the main scanning direction. A first light source unit having a holding body for holding; m (≧ 2) semiconductor lasers; and m coupling lenses corresponding to each of these semiconductor lasers in a 1: 1 relationship;
The m semiconductor lasers and the m coupling lenses are integrally formed while maintaining a predetermined positional relationship such that the optical axes of the m coupling lenses form a predetermined angle in the main scanning direction. A second light source unit having a holding body for holding, n light beams emitted from the first light source unit, and m light beams emitted from the second light source unit as light beams close to each other Beam combining means for combining, and the optical axis direction of each coupling lens in the first and second light source sections, and the mutual positional relationship between the first and second light source sections and the beam combining means are adjacent to each other. The resolution of the synchronous light detecting means: Δ
A multi-beam scanning apparatus which is set so as to be separated by the above-mentioned distance, and configured so that each of the deflected light beams can be individually detected by the synchronous light detecting means. 8. The multi-beam scanning device according to claim 7, wherein n = m and the first light source unit and the second light source unit have the same configuration. 9. The multi-beam scanning device according to claim 8, wherein the light emitting units of the respective semiconductor lasers in the light source device are arranged on the optical axis of the corresponding coupling lens. 10. The multi-beam scanning device according to claim 8, wherein n = m = 2. 11. The multi-beam scanning apparatus according to claim 6, wherein at least P (2) out of N (≧ 2) semiconductor lasers.
≦ P ≦ N) light emitting units are shifted from the optical axis of the corresponding coupling lens in the main scanning direction. 12. The multi-beam scanning device according to claim 7, wherein at least P (2 ≦ P) out of n + m semiconductor lasers.
≦ n + m) light emitting units are shifted from the optical axis of the corresponding coupling lens in the main scanning direction. 13. The multi-beam scanning device according to claim 12, wherein n = m and the first light source unit and the second light source unit have the same configuration. 14. The multi-beam scanning device according to claim 13, wherein n = m = 2. 15. A multi-beam scanning apparatus according to claim 1, wherein a plurality of light beams emitted from the light source device are simultaneously deflected by the same deflecting and reflecting surface of the optical deflector. Wherein the light source device is configured such that the plurality of light beams cross in the main scanning direction in the vicinity of the deflecting reflection surface. 16. A multi-beam scanning apparatus according to claim 1, wherein a plurality of light beams emitted from the light source device are simultaneously deflected by the same deflective reflection surface of the optical deflector. A plurality of light beams from the light source device are formed between the light source device and the optical deflector as a linear image long in the main scanning direction separated from each other in the sub-scanning direction near the deflecting reflection surface. The scanning image forming optical system is an anamorphic one in which the position of the deflecting reflective surface and the position of the surface to be scanned are geometrically conjugated in the sub-scanning direction. A multi-beam scanning device. 17. A light source device used for a multi-beam scanning device, having a configuration according to any one of claims 1 to 16. 18. A plurality of deflected light beams emitted from a light source device and deflected are converged toward a surface to be scanned by a scanning image forming optical system, and are separated from each other in the sub-scanning direction on the surface to be scanned. A multi-beam scanning method for forming a plurality of light spots, and simultaneously scanning a plurality of lines with the plurality of light spots, wherein the method is performed using the multi-beam scanning device according to any one of claims 1 to 15. A multi-beam scanning method. 19. A plurality of deflected light beams emitted from a light source device and deflected are converged toward a surface to be scanned by a scanning image forming optical system, and are separated from each other in the sub-scanning direction on the surface to be scanned. A multi-beam scanning method for forming a plurality of light spots and scanning a plurality of lines simultaneously with the plurality of light spots, wherein the multi-beam scanning method is performed using the multi-beam scanning device according to claim 16. Method. 20. An image forming apparatus for forming a latent image on a latent image carrier by optical scanning and visualizing the latent image to obtain a desired recorded image, wherein the optical scanning device optically scans the latent image carrier. Claim 1
An image forming apparatus using the multi-beam scanning device according to any one of the fifteenth aspects. 21. An image forming apparatus for forming a latent image on a latent image carrier by optical scanning and visualizing the latent image to obtain a desired recorded image, wherein the optical scanning device optically scans the latent image carrier. Claim 16
An image forming apparatus using the multibeam scanning device according to any one of the preceding claims. 22. The image forming apparatus according to claim 20, wherein the latent image carrier is a photoconductive photoconductor, and an electrostatic latent image is formed by uniform charging and optical scanning. An image forming apparatus that visualizes the electrostatic latent image as a toner image.