JP2005266492A - Light source device, optical scanner, image forming apparatus, system, method of positioning optical scanner, and method of manufacturing optical scanner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source device with which the problem that a difference in the optical path lengths is caused since the optical paths are different among luminous fluxes emitted from respective light source parts can be solved, an optical scanner having the same, and an image forming apparatus or the like. <P>SOLUTION: The light source device is composed of a light source part in which the combination of light sources and a first imaging optical system which condenses and couples luminous fluxes from the light sources is integrally supported via a supporting member, and a luminous flux combining means which combines a plurality of luminous fluxes emitted from the light source parts when the luminous fluxes are projected onto a main scanning plane. The light source device is characterized in that spacial center lines of the plurality of luminous fluxes emitted from the respective light source parts are arranged closely to each other. The optical scanner having such a light source device, the image forming apparatus, the system, and a positioning method are provided. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a light source device, an optical scanning device having the device, an image forming apparatus, a system, a method for positioning the optical scanning device, and a method for manufacturing the optical scanning device.

  As an image forming apparatus such as a laser printer equipped with an optical writing type optical system, for example, Japanese Patent Application Laid-Open No. 11-23988 is known. In this publication, a pair of a semiconductor laser and a coupling lens is arranged in the main scanning direction, and a light source unit integrally supporting the pair by a supporting member, and the supporting member is arranged in the sub-scanning direction, and emitted from each light source. It consists of beam combining means that emits light beams close to each other, and is configured so that the light beams emitted from each light source unit intersect in the vicinity of the deflecting reflection surface (polygon mirror reflection surface) when an image is projected in the main scanning direction. It is characterized by that. However, since the invention of this publication has a configuration in which the light source units are arranged side by side in the sub-scanning direction, it becomes higher in the sub-scanning direction. That is, this apparatus has a problem that it becomes large in the height direction as a machine.

  In addition, since the expansion and contraction of each holding member due to the influence of environmental fluctuations is not considered, the expansion and contraction of each holding member causes the relative positional relationship of each optical element to be out of order, and as a result, the sub-scanning beam pitch shifts. In the case of a color machine, there is a drawback that it causes deterioration during the formation of the obtained image, that is, density unevenness and color misregistration in the case of a color machine.

  Japanese Patent Application Laid-Open No. 2003-29180 of Patent Document 2 discloses a light source unit in which a pair of a semiconductor laser and a coupling lens is arranged in the main scanning direction and is integrally supported by a support member, and the support member is a sub-portion. Beam combining means arranged in the scanning direction and emitting light beams emitted from the respective light sources close to each other. An attitude adjusting member is provided between the light source unit (supporting member) and a holding member for holding the light source unit (light source unit ( It is possible to adjust the inclination of the support member) with respect to the sub-scanning direction so that the light beams emitted from the respective light source sections intersect in the vicinity of the deflecting reflection surface (polygon mirror reflection surface) when projected in the main scanning direction. It is characterized by being composed. However, the invention described in this publication does not consider the difference in the optical path lengths of the light beams emitted from the support members arranged in the sub-scanning direction. Furthermore, the description of the examples in this publication merely shows that a configuration in which the difference in optical path length is widened is presented.

  Japanese Patent Laid-Open No. 2002-350758 of Patent Document 3 discloses that two laser light sources that irradiate substantially parallel laser beams and two laser beams from the light sources are brought close to each other, and a predetermined angle with respect to the irradiation direction. An invention of a laser scanning device comprising beam combining means for radiating from substantially the same position in a predetermined radiation direction intersecting at (90 °) and an image forming apparatus provided with the same are disclosed. In the invention described in this publication, a method for synthesizing two light sources (packages) is presented as a light source, but only up to this presentation, and no consideration is given to the difference in the optical path length of the light flux.

Furthermore, Japanese Patent Application Laid-Open No. 2003-107381 of Patent Document 4 discloses a method of combining emitted light beams from a semiconductor laser array (LDA) having a plurality of light emitting points using beam combining means. In this publication, a diaphragm is provided between the deflector and the light source unit, and the light beams intersect at the position of the diaphragm, so that each light beam is shifted on the deflection reflection surface of the deflector, and the width is widened. Therefore, the area of the deflecting / reflecting surface must be increased. As a result, the deflector becomes large and it is difficult to reduce the size of the writing optical system. Also, the motor for driving the deflector is large and its power consumption is large.
Further, this publication only presents a synthesis method, and no consideration is given to the difference in the optical path length of the luminous flux.
Japanese Patent Laid-Open No. 11-23988 JP 2003-29180 A JP 2002-350758 A JP 2003-103871 A

  In order to improve the output speed of image forming devices such as laser printers, a multi-beam optical scanning device has been developed that forms an image by optically scanning an image forming body such as a photoconductor as a scanned medium with a plurality of light beams at once. Has been. As a light source, a combination of a plurality of semiconductor lasers (LD) or a semiconductor laser array (LDA) having a plurality of light emitting points is used.

  As a light source device, a plurality of pairs (sets) consisting of a semiconductor laser and a coupling lens are arranged in the main scanning direction and are integrally supported by a support member (holder), and a light source unit and a support constituting this light source unit A multi-beam light source device that constitutes a light source device has been invented and disclosed by a light beam combining unit that arranges members in the sub-scanning direction and emits light beams emitted from the respective light sources close to each other (for example, Patent Document 1). (See JP-A-11-23988 and JP-A-2003-29180 in Patent Document 2).

In these publications, a light source unit that supports a light source and a coupling lens on a support member and a light beam emitted from each light source unit by a combining prism that is a light beam combining unit are combined and combined. Since the optical paths of the light beams emitted from are different, the optical path length is different.
In addition, since the light source units are arranged in the sub-scanning direction, the sub-scanning direction becomes high, which becomes a factor for increasing the size of the light source device. As a result, the image forming apparatus is also increased in size.

In contrast to the above-described conventional example, a multi-beam light source device that constitutes a light source device is also invented and disclosed by a light beam synthesizing unit that arranges light source unit support members in the main scanning direction and emits light beams emitted from the respective light sources close to each other. (For example, Japanese Patent Application Laid-Open No. 2003-107381 of Patent Document 4).
However, this publication also has a problem that the optical path length is different because the optical paths of the light beams emitted from the respective light source units are different.
The object of the present invention is to provide means for solving the above-mentioned problems.

  According to the first aspect of the present invention, a plurality of sets including a light source and a first imaging optical system that condenses and couples light beams from the light source are integrally supported via a support member and projected onto the main scanning plane. When a plurality of light beams emitted from a plurality of light sources and a plurality of light beam groups emitted from the plurality of light source units are projected onto a main scanning plane, And a combining unit configured to combine the spatial center lines in each of the light beam groups so as to be close to each other between the plurality of light beam groups, wherein the light source device is emitted from each of the light source units. The light source device is arranged so that the intersecting positions of the plurality of light beams are substantially equal.

  According to a second aspect of the present invention, in the first aspect, the light source sections are arranged such that the substantial optical path lengths from the light beam combining means of the light sources are substantially equal for the emitted light beams. And

  According to a third aspect of the present invention, in the second aspect, an optical path correction member is provided between at least one light source section and the holding member so that the optical path lengths are substantially equal.

  According to a fourth aspect of the present invention, in the light source device according to the first to third aspects, the light source unit includes a plurality of light source units having the same configuration.

  According to a fifth aspect of the present invention, in the first aspect, the light source is a laser diode, a semiconductor laser array in which a plurality of light emitting points are arranged on a straight line, or a surface emitting laser array in which a plurality of light emitting points are arranged in a two-dimensional manner. It is characterized by being at least one selected from.

  A sixth aspect of the invention is an optical scanning device on which at least one of the light source devices of the first to fifth aspects is mounted, and the seventh aspect of the invention is an optical scanning device of the sixth aspect. And an image information communication system in which the image forming apparatus according to claim 7 and a computer are connected via a network.

  The present invention also provides a method for positioning an optical scanning device. By applying such a method, the optical scanning device of the present invention is manufactured.

  That is, according to the present invention (for example, claim 1), by configuring the light beams emitted from the light source sections to intersect in the main scanning direction, the separation of the light beams on the deflection reflection surface is reduced, and the deflection reflection surface is reduced. This makes it possible to make the deflector small. In the present invention, the light source units are arranged in the main scanning direction, and the spatial center lines of the light beams emitted from the light source unit are brought close to each other by the combining prism that is the light beam combining unit, so And a multi-beam light source unit can be realized.

  According to the second and third aspects of the present invention, by equalizing the optical path length from the light source to the exit position of the light beam synthesizing means, the incident conditions of the light beams emitted from the light source units to the scanning optical system are made equal, and the scanned object is scanned. The imaging performance on the surface can be made substantially equal, and each light source unit can be shared.

  According to the fourth aspect of the present invention, it is possible to make each light source unit common, to reduce the types of assembly adjustment, and to reduce the number of management components.

  The invention according to claim 5 is a semiconductor laser array (LDA) in which light emitting points are arranged on a common element on a straight line, or a surface emitting laser array in which light emitting points are two-dimensionally arranged on a common element. By using as a light source, it is possible to further increase the number of beams as the light source device.

  According to the sixth aspect of the present invention, an optical scanning device capable of multi-beam writing can be formed by incorporating any of the light source devices of the present invention described above.

  According to the seventh aspect of the present invention, an image forming apparatus capable of multi-beam writing can be formed by incorporating any one of the above-described optical scanning apparatuses according to the present invention. It is preferable to position the optical scanning device by displacing the center point that can be created from the center point of the light spot, and to position the light source by applying such a positioning method.

  The present invention is illustrated by examples.

[Configuration / Operation Example]
FIG. 1 shows an example of the overall configuration of a multi-beam optical scanning device including the light source device of the present invention. In this figure, the state seen from the main scanning direction is schematically shown. In FIG. 1, the holding parts for each optical element are omitted.
A light emitting portion comprising a light source 1A-1 having a semiconductor laser (LD) and a coupling lens 2A-1 (first imaging optical system) that collects a divergent light beam (hereinafter referred to as a light beam) from the light source. And a pair of light emitting portions composed of a coupling lens 2A-2 that condenses the light beam from the light source 1A-2 are integrally supported by a support member (not shown) to constitute the light source portion 12A. Is done.

  For example, the light source unit 12A fixes the light source 1A-1 and the light source 1A-2 to aluminum die cast holders 101-1 and 101-2 (not shown), respectively, It is formed by being fixed to a common support member 102A (not shown) via a fixing means such as a screw. The holders 101-1 and 101-2 may be configured to hold and hold the light sources 1A-1 and 1A-2 between a plate-like member and a fixing means such as a screw, for example. The light source 1A-1 and the like may be fixed by fitting or the like by drilling holes.

  As shown in FIG. 2, the coupling lenses 2A-1 and 2A-2 respectively convert the light beams emitted from the corresponding light sources 1A-1 and 1A-2 into any state of a parallel light beam, a convergent light beam, or a divergent light beam. Coupling so that the positions in the optical axis direction of the lens are aligned to form a pair (couple) with the light source and formed on the support member 102A shown in FIG. 2A, for example, a V-shaped groove or U A shape groove is formed in the support portions 103A-1 and 103A-2 (not shown), and a gap between the groove and the coupling lens (a gap between the surface contacting the coupling lens on the support portion and the coupling lens) ) Can be fixed by irradiating with UV after applying a UV curable adhesive, for example.

  Similarly, as shown in FIG. 2A, in the second light source unit 12B, the light sources 1B-1 and 1B-2 are fixed to the holders 101B-1 and 101B-2, respectively, and the holders 101B-1 and 101B -2 is fixed to the support member 102B in the same manner as described above, and the coupling lenses 2B-1 and 2B-2 are integrally supported by the support member 102B to constitute the light source unit 12B. Here, the light source portions 12A and 12B may be integrally formed as a single component on the different support members. 2A shows an example in which a plurality of light source units 12A and 12B (two light source units) are integrally formed on one support member.

  As shown in FIGS. 2A and 5, the light source units 12A and 12B are arranged side by side in the main scanning direction (the arrow direction in the drawing in the drawing), and cylindrical portions 104A and 104B (not shown) on the support member. ) And a hole 105A, 106B is formed in the holding member 105 (see FIG. 2A) common to each support member, for example, to form holes 106A, 106B. The light source is brought into contact with the cylindrical portion with reference to the positioning portion formed on each support member, and is fixed from the front side of the holding member 105 through a screw. Here, the supporting members 102A and 102B shown in FIG. 2A are configured to be rotatable around the centers of the cylindrical portions 104A and 104B and to be fixed at arbitrary positions. Thereby, the light beam emitted from the support member can be tilted.

By arranging the light source units 12A and 12B side by side in the main scanning direction (for example, the horizontal direction in FIG. 5), the light source devices disclosed in Patent Document 1 and Patent Document 2 described above are arranged in the sub-scanning direction (for example, FIG. 5) (the direction perpendicular to the sheet of FIG. 5) can be reduced.
In the holding member 105, plates (apertures) 107A and 107B provided with aperture stops 3A-1, 3A-2 and 3B-1, 3B-2 as shown in FIGS. The spatial center line 14A of the exit beams from 1A-1 and 1A-2 is combined with the spatial center line 14B of the exit beams from the light sources 1B-1 and 1B-2 together with the main scanning direction and the sub-scanning direction. A beam combining prism 4 (light beam combining means) for allowing the light to be emitted is supported. The spatial center lines 14A and 14B of the exit beam from the beam combining prism 4 are configured to be parallel. In the present invention, the axis 14A shown in FIG. 5 is the central axis (optical axis) of the light flux from each light source.

The holding member 105 configured as described above and shown in FIG. 5 is assembled to an optical housing 108 (not shown) that houses the scanning optical means, and allows a plurality of beams to enter the scanning optical means. The holding member 105 may be assembled directly to the optical housing or may be assembled via a bracket.
On the other hand, a substrate 109 (not shown) on which a drive circuit for a semiconductor laser (LD) as a light source is formed is fixed to a support 110 (not shown), and the semiconductor laser leads are joined by solder or the like to make circuit connection. Made.
The above is the description of the light source device (claim 1).

  In the first light source unit 12A, as shown in FIG. 1, the light flux emitted from the light source 1A-1 is regulated by the aperture stop 3A-1 and passed through the beam synthesis prism 4 (light flux synthesis means) (transmitted). ), Main scanning in the vicinity of one point on the deflecting / reflecting surface 6A of the deflector 6 (polygon scanner: scanner using a polygon mirror) by the cylindrical lens 5 (second imaging optical system) which is a line image imaging optical system. Condensed linearly long in the direction.

As shown in FIG. 1, the deflector 6 rotates at an equiangular speed about the rotation axis 6B, and deflects the incident light beam at the equiangular speed. A third imaging optical system 7 (scanning optical system: FIG. 1 shows an example of a two-lens configuration between the deflector 6 and the scanned medium 9. In the present invention, this is used for this scanning optical system. The number of lenses is not particularly limited, and a reflection optical system (a mirror or a mirror and a lens system may be used, or a combination thereof may be used) is arranged and deflected by the deflecting reflection surface 6A. The light beam 8a-A1 forms a light spot 10a-A1 on the scanned medium 9. The light spot 10a-A1 is optically scanned on the scanned medium 9 by the rotation of the deflector 6, for example, in the direction of the arrow shown in FIG. 1 (in the direction of the arrow in the deflector 6 which is the polygon scanner of FIG. 1). The light is scanned by the rotation of).
Similarly, the light beam emitted from the light source 1A-2 is regulated by the aperture stop 3A-2, and the width of the light beam is controlled (transmitted) through the beam combining prism 4 to be a cylindrical lens 5 (second image forming optical system). The imaging optical system) converges in a linear shape in the vicinity of the deflection reflection surface 6A of the deflector 6 (polygon scanner) in the main scanning direction.

Here, the aperture stops 3A-1 and 3A-2 may be provided separately, or may be formed integrally.
The light beam 8b-A2 deflected by the deflecting reflection surface 6A forms a light spot 10b-A2 on the scanned medium 9, and the light spot 10b-A2 is rotated on the scanned medium 9 by the rotation of the deflector 6. Similarly to the above, optical scanning is performed in the direction of the arrow shown in FIG.

  The light beam emitted from the light source 1A-1 and the light beam emitted from the light source 1A-2 are configured to intersect in the vicinity of the deflecting / reflecting surface 6A. With respect to the light beam emitted from the light source 1A-1, the light beam emitted from the light source 1A-2 is deflected by φ / 2, which is half the angle φ formed by the light beams emitted from the light sources 1A-1 and 1A-2, and deflected The apparatus is configured to perform deflection scanning with the device 6 shifted. With this configuration, the light beams 8a-A1 and 8b-A2 from the light sources 1A-1 and 1A-2 reflected by the deflecting / reflecting surface 6A can pass through the optical path on the third imaging optical system, which is a scanning optical system. It is possible to reduce the image formation image plane tilt due to the scanning light beam on the surface to be scanned, and to prevent the image formation performance (field curvature, magnification error, etc.) from deteriorating.

In other words, the light beams emitted from the respective light sources of the light source unit 12A are arranged and configured so as to intersect in the vicinity of the deflection reflection surface 6A of the deflector when projected onto the main scanning plane.
Similarly, in the second light source unit 12B, the light beam emitted from the light source 1B-1 is regulated in its beam width by the aperture stop 3B-1 and is reflected (reflected) by the beam combining prism 4 so that the line image imaging optics. By a cylindrical lens 5 (second imaging optical system) which is a system, light is condensed in the vicinity of the deflecting reflection surface 6A of the deflector 6 (polygon scanner) in a linear shape in the main scanning direction.

The light beam 8a-B1 deflected by the deflecting reflecting surface 6A forms a light spot 10a-B1 on the scanned medium 9, and the light spot 10a-B1 is rotated by the deflector 6 (in the direction of the arrow in the figure). The top is optically scanned in the direction of the arrow in the figure.
The same applies to the luminous flux emitted from the light source 1B-2.
Similarly to the light source unit 12A, the light beam emitted from the light source 1B-1 and the light beam emitted from the light source 1B-2 are configured to intersect in the vicinity of the deflecting reflection surface 6A, and are generated by the scanning light beam on the scanned surface. A configuration in which the tilt of the image plane is reduced and the degradation of the imaging performance (field curvature, magnification error, etc.) is prevented.

The light source section 12A as shown in FIG. 2A is a spatial center of each optical axis that passes near the intersection of the optical axes (emitted axes) of the light beams emitted from the light sources 1A-1 and 1A-2. The line 14A (or an axis substantially parallel to 14A) is configured as the rotation axis. Similarly, the light source unit 12B can also rotate around the spatial center line 14B of each optical axis (or an axis substantially parallel to 14B) passing through the vicinity of the intersection of the optical axis (exit axis) of the emitted light beam. And Thereby, the arrangement of the light beams emitted from the respective light source units can be tilted.
That is, in FIG. 2A, the light source unit is configured to include two light sources. However, in the present invention, the light source unit may include a plurality of light sources. As described above, the line 14A or 14B has intersections of the optical axes of a plurality of light beams, and these line segments may be configured to be rotationally symmetric axes of the light source unit. preferable.

The beam combining prism 4 (light beam combining means) has a polarization separation film 4A, and a light beam emitted from the light source unit 12A passes through the polarization separation film 4A. The light beam emitted from the light source unit 12B is rotated by 90 degrees from the original state in the polarization direction by a half-wave plate (1/2 lambda plate: 1 / 2λ plate) 13 shown in FIG. Thereafter, the light is sequentially reflected by the prism surface 4B and the polarization separation film (polarization separation interface) 4A, and is emitted from the beam combining prism 4.
By adopting such a configuration, the light source units 12A and 12B can be arranged on a plane (preferably on the same plane), so that a single drive board for driving a semiconductor laser as a light source is configured. And the configuration can be simplified.

The light beam emitted from the light source unit 12A and the light beam emitted from the light source unit 12B are shifted in polarization direction by 90 degrees by the half-wave plate 13, so that the transmission and reflection characteristics with respect to the incident angle (reflection angle) with respect to each optical element are In contrast, there is a difference in the amount of light at each scanning position on the surface to be scanned, thereby causing unevenness in the amount of light. This unevenness in the amount of light becomes unevenness in the density of the output image, particularly in a color image output machine, which causes the image quality to deteriorate.
As a method of reducing this unevenness in light quantity, a 1/4 wavelength plate (1 / 4λ plate) is disposed immediately after the beam combining prism 4 (on the side from which the light beam is emitted), and the polarization direction of the light beam is rotated by 45 degrees. This can be reduced.

  For example, as shown in FIG. 1, the synchronization detection optical system 11 has a configuration in which a light beam deflected by a deflector 6 passes through a mirror 11-3 and a synchronization detection imaging element 11-2, and is then The deflected light beam is guided to the synchronous detection sensor 11-1 constituted by a diode or the like. Then, when the light beam passes over the synchronization detection sensor 11-1, a synchronization signal is generated and processed by a synchronization circuit (not shown), and a write start signal is transmitted after a certain timing (or a predetermined time). To do. The certain timing here is, for example, the time from the detection position of the synchronization detection sensor 11-1 to the writing start position (however, the light source may not emit light during this period).

As the imaging element 11-2 for synchronization detection, any of a lens having power (refractive power) only in the sub-scanning direction, a lens having power only in the main scanning direction, and a lens having power in both main and sub-directions may be used. . Further, as the synchronization detecting imaging element 11-2, a mirror or the like may be used instead of the above-described lens. As this mirror, it is preferable to use a mirror having a light collecting power (such as a concave mirror). Alternatively, the synchronization detection imaging element 11-2 is not used, and the mirror 11-3 can be used to guide (for example, directly) to the synchronization detection sensor 11-1 using the above-described mirror or as described above. The synchronization detection optical system 11 may be configured using appropriate mirrors and lenses as appropriate.
The above is the description of the optical scanning device (claim 6).

FIG. 2A is a diagram for explaining the details of the light source device, as viewed from the main scanning direction.
Spatial center lines 14A of the optical axes 15A-1 and 15A-2 (each indicated by dotted lines) of the light beams emitted from the light sources 1A-1 and 1A-2 of the light source unit 12A, and each of the light source units 12B The spatial center line 14B of the optical axes 15B-1 and 15B-2 (similarly indicated by dotted lines) of the light beams emitted from the light sources 1B-1 and 1B-2 is the one after passing through the beam combining prism 4 Is synthesized as a close luminous flux.
The light beams emitted from the beam combining prism 4 are combined in the main scanning direction.
The light source units 12A and 12B and the beam combining prism 4 are integrally held in parallel on a common plate-like holding member 105.

FIG. 2B is a diagram for explaining the details of the light beam emitted from the light source unit in the sub-scanning direction and schematically showing the state seen from the sub-scanning direction.
The emission directions of the light beams emitted from the light sources 1A-1 and 1A-2 of the light source unit 12A are substantially parallel in the sub-scanning direction, and are sub-scanned with respect to the optical axes of the corresponding coupling lenses 2A-1 and 2A-2, respectively. Accordingly, the light beams emitted from the beam combining prism 4 are emitted at an angle in the sub-scanning direction.

  The same applies to the light beams emitted from the light sources 1B-1 and 1B-2 of the light source unit 12B. In FIG. 2B, since the light sources and the coupling lens overlap when viewed from the sub-scanning direction, the light source and the coupling lens on the back side are omitted.

By holding each light source unit in close proximity to a common holding member 105, the influence of environmental fluctuations due to temperature fluctuations and the like becomes substantially equal, and the influence on optical characteristics (scanning pitch and imaging position fluctuations) can be reduced. it can.
Furthermore, by using a material having a linear expansion coefficient close to the holder and the supporting member constituting the light source unit, or a holding member that holds the light source unit in common, or the same material, the ratio of expansion and contraction of each member due to temperature fluctuations can be set. It is approximately the same, reducing deformation caused by distortion when temperature fluctuations occur and distortion caused by stress generated at the screw fastening part, and maintaining the relative positional relationship of the light flux emitted from each light source on the scanned surface. become able to.

  In the sub-scanning direction, the positional relationship between the light emitting points of the semiconductor laser, which is the light source, and the relative positional relationship between the scanning spots on the scanned medium are the imaging system between the light source and the scanned medium (see FIG. In the example 1, the coupling lenses 2A-1, 2B-1,..., The cylindrical lens 5, and the third imaging optical system 7) are determined according to the composite magnification in the sub-scanning direction: β, The arrangement is set so that the scanning interval (scanning pitch) of the scanning lines becomes a desired value.

  However, as shown in FIG. 3, the optical path length of the light beam emitted from the light source unit 12B shown in FIG. 1 is equal to that of the prism surface 4B of the beam combining prism 4 shown in FIG. It becomes longer by an amount corresponding to the interval from 4A (interval shown in FIG. 2A: L). Therefore, when the light source units 12A and 12B are configured to have the same structure, and the crossing angle φ of the emitted light beams is equalized between the light source units 12A and 12B, as shown in FIG. There is a difference between the position where the light beams emitted from 12A intersect and the position where the light beams emitted from light source unit 12B intersect. Thereby, in the vicinity of the deflecting / reflecting surface 6A, the light beams emitted from at least one of the light source units do not cross each other, and the imaging image surface falls down, leading to performance deterioration.

This will be described in more detail with reference to FIG. FIG. 3 is a diagram showing an optical path from the light source device viewed from the main scanning direction. This diagram is a diagram in which the optical path is developed on a plane. In order to make the relationship easy to understand, the exit surface 4C of the beam combining prism 4 is shown. It is the figure typically shown on the basis. For this reason, the other configurations are omitted from the drawing.
The light sources 1A-1 and 1A-2 that emit light beams that pass through the beam combining prism 4 are arranged so that the emitted light beams have an intersection angle φ, and are transmitted through the beam combining prism 4D (indicated by a dotted line in the figure) and then positioned. At 19 the two light beams intersect. The light sources 1B-1 and 1B-2 that emit light beams reflected and deflected by the beam combining prism 4 are arranged so that the emitted light beams also have an intersecting angle φ, and are reflected at the position 20 after reflection and deflection by the beam combining prism 4E. Two light beams intersect. In FIG. 3, AX is a combined optical axis of spatial centerlines (in other words, symmetry axes) of the light sources 1A-1 and 1A-2 and the light sources 1B-1 and 1B-2.

  Since the actual optical path length of the beam combining prism 4 is different between the light source units 12A and 12B, the actual optical path length is 4E in the light source unit 12A as in the beam combining prism 4D in the light source unit 12B. The reflected and deflected light beam is lifted by the beam combining prism 4E (substantially the focal point becomes longer) and the crossing position extends to approach the position 19, but the optical path length difference L by the beam combining prism L Therefore, the positions 19 and 20 where the light beams intersect with each other are shifted by Δ.

  As described when explaining FIG. 1, in order to prevent the deterioration of the imaging performance on the surface to be scanned, the crossing position of each light beam is set in the vicinity of the deflecting reflection surface to reduce the tilt of the imaging surface. There is a need. For this purpose, the positions 19 and 20 should be matched and crossed in the vicinity of the deflecting reflection surface. For this purpose, the crossing angle φ of the light beams emitted from the light source units 12A and 12B is different, for example, each crossing angle θ1 and , Θ2, and a method in which the light beams emitted from the respective light source sections intersect with each other in the vicinity of the deflecting reflection surface 6A so as to correspond to each other.

In order to apply this method, it is necessary to adjust the light source units 12A and 12B separately, and the adjustment amount may be changed or the process may be complicated in the adjustment process. It is necessary to store and manage, and each work becomes complicated.
In addition, in order to avoid the possibility of mounting the light source units 12A and 12B in error, if the components that make up the light source units 12A and 12B are separate parts, it will not be possible to share the parts, further increasing costs and complicating management work. Leads to.

  In the present invention, in order to overcome such difficulties, the distance between the light source 1A-1 and the beam combining prism 4 of 1A-2 (light source unit 12A) in FIG. 3 corresponds to Δ as shown in FIG. The amount was extended with respect to the light source 1A (away from the beam combining prism 4 by Δ), and the device was devised so that the positions 19 and 20 coincided.

In this way, even if the crossing angle φ of the light source units 12A and 12B is set to the same angle by moving the light source unit on the side transmitting the beam combining prism 4 away from the beam combining prism 4 as shown in FIG. The crossing positions of the luminous fluxes emitted from can be matched (substantially intersect at one point).
The distance can be achieved by making the distance between the prism surface 4B and the polarization separation film 4A optically substantially the same (making the optical path lengths substantially the same).

Accordingly, the intersection position of the light beams emitted from the respective light source units can be set near the deflecting reflection surface, and therefore, it is possible to prevent the image forming performance from being deteriorated on the surface to be scanned.
Here, as a means for moving the light source portion whose optical path length is shorter by Δ with respect to the combining prism 4 from the beam combining prism 4, the optical path length can be changed by providing a step in the holding member 105. However, when the step is provided directly on the holding member 105, the shape of the holding member 105 becomes complicated. Therefore, as shown in FIG. 5, an optical path correction member 21 is provided between the light source unit 12A and the holding member 105 holding the light source unit 12A. The optical path length may be changed by arranging it (claim 3).

  FIG. 6 is a diagram schematically showing the arrangement of light spots by the light beams emitted from the respective light sources on the surface to be scanned. Each light spot is arranged at a scanning interval Pi in the sub-scanning direction. This scanning interval Pi is determined by the writing density. For example, it can be 42.3 μm for 600 dpi and 21.2 μm for 1200 dpi.

  The light spots of the light beams 15A-1 and 15A-2 emitted from the light source unit 12A are 17A-1 and 17A-2, respectively, and the light spots of the light beams 15B-1 and 15B-2 emitted from the light source unit 12B Are 17B-1 and 17B-2, respectively. At this time, 17A-3 and 17B-3 indicate points (center points) representing the center positions between the light spots of the respective light source units. This center point indicates the position where the spatial center lines 14A and 14B of the optical axis (exit axis) of the light beam emitted from each light source unit intersect with the scanned medium.

The light source units 12A and 12B are configured to be rotatable about the above-described spatial center lines 14A and 14B as rotation axes.
With this configuration, when the light source unit 12A is rotated about the center line 14A as the rotation axis, the interval between the light sources 1A-1 and 1A-2 in the sub-scanning direction can be changed. Similarly to the light source unit 12A, the light source unit 12B can change the interval between the light sources 1B-1 and 1B-2 in the sub-scanning direction.
The center points 17A-3 and 17B-3 are points representing the positions where the optical axes 14A and 14B reach the scanned medium via the respective optical systems. From this, the light spot caused by the light beams emitted from the light sources 1A-1 and 1A-2 and 1B-1 and 1B-2 can be displaced about 17A-3 and 17B-3. That is, in the present invention, by adopting such an arrangement, the scanning interval in the sub-scanning direction can be freely changed.

  As described above, in the sub-scanning direction, the relative positional relationship between the light emitting point interval of the light source and the scanned medium is determined by the combined lateral magnification β of the imaging system disposed therebetween. The light spot 17A-1 and 17A-2, 17B-1 and 17B-2 on the scanned medium are obtained by multiplying the change amount of the light emitting point interval in the sub-scanning direction by β, and the center points 17A-3 and 17B-3. And the scanning intervals Pi1 and Pi2 change.

  Furthermore, by rotating the light source device with the combined optical axis AX as the rotation center axis, the midpoints that can be created from the center points 17A-3 and 17B-3 of the light spot on the surface to be scanned, and further from these center points It can be displaced around 18. Thereby, all the scanning intervals Pi1, Pi2, and Pi3 can be displaced. Therefore, in the present invention, the scanning intervals Pi1, Pi2, Pi3,... Can all be adjusted by appropriately combining the rotation of the light source device and the rotation of the light source unit.

  Thus, in the present invention, the scanning interval on the scanned medium can be freely adjusted. Further, in the present invention, it is possible to adjust the relative position of the light emitting point of each light source with substantially the same amount of change with the spatial center line as the rotation axis, and the present invention adjusts the positional relationship. It can be easily done.

The following points can be mentioned as effects obtained by rotationally adjusting the positioning of the light source unit or the optical element using the spatial center line of the light beam emitted from the light source unit or a substantially parallel axis as the rotation axis. It is done.
When the processing accuracy of the optical element and an error due to assembly occur, the scanning interval Pi on the scanned medium 9 deviates from the target (designed position) interval. However, by making the spatial center line of the emitted light beam from the light source section rotatable as a rotation axis, due to processing errors of the light source device components, processing errors of each component constituting the writing optical system, etc. When the scanning interval of the light beam on the scanned medium deviates from a desired or designed expected interval, it can be adjusted to a correct scanning interval.

  As an embodiment described above, there can be mentioned a case where two sets of a semiconductor laser as a light source and a coupling lens (first imaging optical system) are combined in one light source unit. As a modified example of this example, a larger number of groups (for example, a plurality of groups such as 3, 4,..., But in the present invention, the number of groups is not particularly limited) may be combined.

  Thus, by configuring a light source unit using a plurality of light sources (LD) and further combining a plurality of such light source units, the number of light beams scanned on the scanned medium 9 can be increased freely. With this configuration, the image forming apparatus equipped with the writing optical system including the light source unit of the present invention can improve the output speed. Even if the output speed is not changed, the present invention can reduce the rotational speed of the deflector. Accordingly, in the present invention, it is possible to configure a writing optical system that takes into consideration the environment such as reduction of power consumption and reduction of heat generation.

Next, as means for improving the output speed, means other than increasing the number of light sources and light source units as described above will be described below.
Regarding the light source, the semiconductor laser (LD) has been described as an example in the above embodiment, but in the present invention, a semiconductor laser array (LDA) in which a plurality of light emitting points are arranged in a monolithic array instead of the semiconductor laser (LD). : Monolithic laser array) can be used as a light source. Thereby, in this invention, the effect equivalent to the light source using the semiconductor laser (LD) mentioned above can be acquired. When a light source unit using such a semiconductor laser array (LDA) is used, divergent light beams emitted from a plurality of light emitting points can be coupled by a common coupling lens, and a combination of these can be configured as a light source unit. Also good.
In the present invention, as another light source, a surface emitting laser array (surface emitting laser array) in which a plurality of light emitting points are two-dimensionally arrayed is used in combination with a coupling lens to constitute a light source unit. (Claim 5).

FIG. 7 is a diagram showing a schematic configuration of an image forming apparatus 30 on which the scanning optical system of the present invention is mounted.
For example, as shown in FIG. 7, a document 31 is placed on a contact glass 32, light for reading a document is irradiated by a lamp 33, and image light on the document is guided to a scanner lens block 34 by a mirror. The converted image data 35 is converted into image data by the CCD, and the converted image data 35 is transferred to the multi-beam optical scanning device 36 of the present invention. Scanned as a spot. Then, the light spot is optically scanned on the photosensitive member charged by the charger 40 to form an electrostatic latent image, which is developed as a toner image by the developing device 37, and the paper is fed from the paper feeding tray 38 by the paper feeding roller 39. After being guided to the photosensitive member and transferred onto the paper by the transfer roller 40, the toner image is fixed by the fixing device 41 and discharged to the paper discharge tray 42 by the paper discharge roller 44. The photoreceptor 20 is subjected to charge removal and cleaning by the charge removal / cleaner 43, and the process from charging as described above is repeated in the same manner.
By incorporating the light source unit or the optical scanning device of the present invention into the image forming apparatus, it is possible to form an image forming apparatus capable of multi-beam writing without wasteful light utilization efficiency.

  Further, by connecting the image forming apparatus of the present invention to an electronic arithmetic device (computer, etc.), an image information communication system (facsimile etc.), etc. via a network, for example, output from a plurality of devices with one image forming apparatus. An information processing system that can process an instruction (output job) can be formed.

  In the present invention, a plurality of image forming apparatuses are connected on a network (a network including the Internet or an intranet connected by wire or wireless: a network including a wired or wireless connection such as a LAN or WAN). Well, when such a system is constructed, it is possible to know the status of each image forming apparatus (the degree of job congestion, whether the power is on, whether it is broken, etc.) from each output request. The image output device or the image output system most suitable for the user's wishes can be configured, and the user can freely select any one of these image output devices as appropriate, and can freely output Will be able to.

  The light source unit of the present invention can cross a plurality of light beams emitted from the light source on the surface of a polygon scanner which is a light deflecting unit. Such an optical scanning device having a plurality of light source units preferably employs a configuration in which a plurality of light beams from the light source units are condensed (intersects on the surface of the polygon scanner) on the surface of a polygon scanner which is a light deflection unit. If such an optical scanning device is employed in an image forming apparatus, an image forming apparatus having a more compact optical deflecting means can be obtained, and an optical scanning device and an image forming apparatus that are smaller than conventional ones can be provided. . In addition, these devices can more easily arrange the optical components, leading to cost reduction during manufacturing, and are also industrially effective in downsizing the components, improving yield, and reducing manufacturing time. Is increased by the present invention.

It is a figure which shows an example of the whole structure of the multi-beam optical scanning device containing the light source device of this invention. (A) is a figure for demonstrating the detail of a light source device, and is the figure seen from the main scanning direction, (b) is for demonstrating the detail of the subscanning direction of the light beam inject | emitted from a light source part. It is a figure which shows typically the state seen from the subscanning direction. It is a diagram showing the optical path from the light source device viewed from the main scanning direction, and is a diagram in which the optical path is developed on a plane, schematically showing the exit surface 4C of the beam combining prism 4 as a reference for easy understanding of the relationship. It is a figure. It is a figure for demonstrating the spatial arrangement | positioning and optical path difference of the optical scanning device of this invention. It is the figure which showed the structure which assembled | attached the holding member to the optical housing 21 which accommodates a scanning optical means. It is a figure which shows typically arrangement | positioning of the light spot by the light beam inject | emitted from each light source on a to-be-scanned surface. 1 is a diagram illustrating a schematic configuration of an image forming apparatus in which a scanning optical system including a light source unit of the present invention is mounted.

Explanation of symbols

1A, 1B Light source (LD)
2A, 2B coupling lens 3A, 3B aperture 4 beam combining prism 5 cylindrical lens 6 polygon scanner (deflector)
7 Third imaging optical system 8 Light beam 9 Scanned medium

Claims (10)

When a plurality of sets including a light source and a first imaging optical system that condenses and couples light beams from the light source are integrally supported via a support member and projected onto a main scanning plane, the plurality of light sources A light source configured to intersect a plurality of light beams emitted from
When combining a plurality of light beam groups emitted from a plurality of light source units onto a main scanning plane, combining so that spatial center lines in each light beam group are close to each other between the plurality of light beam groups Means,
A light source device comprising:
The light source device is arranged so that crossing positions of a plurality of light beams emitted from the respective light source units are substantially equal. In claim 1,
Each light source unit is arranged so that the substantial optical path length from the light beam combining means of each light source becomes substantially equal for each emitted light beam. In claim 2,
A light source device characterized in that an optical path correction member is provided between at least one light source section and a holding member so that the optical path lengths are substantially equal.   4. The light source device according to claim 1, wherein the light source unit uses a plurality of light source units having the same configuration. In claim 1,
The light source is at least one selected from a laser diode, a semiconductor laser array in which a plurality of light emitting points are arranged in a straight line, or a surface emitting laser array in which a plurality of light emitting points are arranged in a two-dimensional manner. A light source device.   An optical scanning device equipped with at least one of the light source devices according to claim 1.   An image forming apparatus equipped with the optical scanning device according to claim 6.   An image information communication system in which the image forming apparatus according to claim 7 and a computer are connected via a network.   A method of positioning the optical scanning device by displacing a center point that can be created from the center point of the light spot on the surface to be scanned.   A method for manufacturing an optical scanning device, wherein the method according to claim 9 is applied to position a light source.

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