JP4728584B2 - Optical scanning apparatus, image forming apparatus, and color image forming apparatus - Google Patents

Description

  The present invention relates to an optical scanning device, an image forming apparatus, and a color image forming apparatus that constitute an optical writing optical system.

  Conventionally, in order to improve the output speed of an image forming apparatus such as a laser printer, a multi-beam optical scanning apparatus has been developed that forms an image by optically scanning a scanned medium (an image forming body such as a photoreceptor) at once with a plurality of light beams. Has been. As a light source, a plurality of semiconductor lasers (LD) are combined, or a semiconductor laser array (LDA) having a plurality of light emitting points is used. In addition, a method of independently using a vertical cavity surface emitting laser array (VCSEL) having a plurality of light emitting lasers arranged two-dimensionally has been developed.

  As an example of the prior art, first, regarding a combination of a plurality of light sources, 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 (light source unit). And beam combining means for emitting the light beams emitted from the respective light sources close to each other. When projected in the main scanning direction, the light beams emitted from the respective light source portions intersect in the vicinity of the deflection reflection surface (polygon reflection surface). There are a “multi-beam light source device” and a “multi-beam scanning device” characterized by being configured to do so (see, for example, Patent Documents 1 and 2).

On the other hand, with respect to a light source in which light emitting points are arranged two-dimensionally, a “multi-beam scanning device” that effectively reduces the density unevenness of the recorded image while ensuring the writing speed or the density unevenness of the recorded image while ensuring the scanning speed. There is a “multi-beam scanning device” that can effectively reduce the above-mentioned problem, avoids the problem of thermal stroke, and realizes high density recording images (see, for example, Patent Documents 3 and 4). Further, as the same basic structure as Patent Documents 3 and 4, there are "surface emitting laser pattern of multi-beam laser scanner" and "multi-beam light source, optical scanning device, and image forming method and apparatus" (for example, Patent References 5 and 6).
Japanese Patent Laid-Open No. 11-23988 Japanese Patent Laid-Open No. 9-236763 Japanese Patent Laid-Open No. 10-301044 JP 2001-350111 A JP-A-9-36497 JP 2003-255247 A

  However, in the inventions described in Patent Documents 1 and 2, the beam combining means uses the polarization of the semiconductor laser, and considering the light utilization efficiency, the beam divergence direction (direction of the active layer) of each semiconductor laser is aligned. Therefore, a half-wave plate is required in the middle of the optical path. Thus, the cost of the beam combining means increases.

  In the inventions described in Patent Documents 3 and 4 above, an optical scanning device is configured using a light source in which a plurality of light emitting sources are two-dimensionally arranged. No method is stated.

  In the inventions described in Patent Documents 5 and 6, a vertical cavity surface emitting laser array (VCSEL) having a plurality of light emitting lasers arranged two-dimensionally as a light source is disclosed. Is not mentioned.

  The present invention has been made in view of the above circumstances, and provides an optical scanning device, an image forming apparatus, and a color image forming apparatus that constitute a light source device by combining a plurality of the surface emitting laser arrays to further increase the speed. For the purpose. Specific objects of the present invention are as follows.

  The present invention uses a vertical cavity surface emitting laser array having a plurality of light emitting lasers arranged two-dimensionally as a light source, and combines a plurality of sets (light source portions) of the same with a coupling lens. An object of the present invention is to increase the number of light beams for optical scanning on a scanning medium and improve the output speed of the image forming apparatus.

  Further, the present invention is configured such that the light beams emitted from the respective light sources intersect in the main scanning direction, thereby making it possible to reduce the separation of each light beam on the deflection reflection surface and to reduce the deflection reflection surface, The object is to make it possible to reduce the size of the deflector.

  Another object of the present invention is to reduce the tilt of the imaging image plane of the scanning light beam on the surface to be scanned, and to prevent the deterioration of the imaging performance (field curvature, magnification error, etc.) of each light spot. .

  Another object of the present invention is to hold each light source unit close to each other so that the influences of environmental fluctuations due to temperature fluctuations are substantially equal, and the influence on optical characteristics (scanning pitch and imaging position fluctuations) is reduced. And

  Another object of the present invention is to construct a multi-beam light source unit by utilizing the fact that a surface emitting laser has a small operating current and therefore generates a small amount of heat and has little influence of thermal interference between adjacent light emitting points arranged. To do.

  Another object of the present invention is to eliminate the need for a half-wave plate by changing the polarization direction of light beams synthesized by a beam synthesis prism by 90 °.

In order to achieve such an object, the optical scanning device of the present invention guides a light beam from a light source to a deflector, and the light beam deflected by the deflector forms a light spot on a scanned medium by a scanning optical system to perform deflection scanning. In the optical scanning device, the light source is a vertical cavity surface emitting laser array in which a plurality of independently-modulated light emitting points are two-dimensionally arranged, and the light source is coupled with a divergent light beam emitted from the light source. A light source device is configured by combining a plurality of sets of lenses, and light beams emitted from the plurality of sets of light sources and coupling lenses are combined by a light beam combining unit that combines the light beams through an aperture stop that regulates the light beams. is configured to be synthesized, the arrangement of light emitting points of the plurality of light sources are the same, at least one light source of the polarization direction of the plurality of light sources, the polarization direction and the other light source Unlike 0 degrees, the light intensity distribution of the light beam emitted from the light source is characterized by a circular.

Further, in the optical scanning device of the present invention , the plurality of groups are integrally supported via the support member, and are projected when viewed on the main scanning plane which is a plane orthogonal to the rotation axis of the deflector. The plurality of luminous fluxes are configured to intersect each other.

An image forming apparatus according to the present invention includes the optical scanning device according to the present invention .

The color image forming apparatus of the present invention is equipped with the optical scanning apparatus of the present invention .

  According to the present invention, the rotational speed of the deflector can be reduced compared with the case where the scanned medium is optically scanned by the light flux from one light emitting point, so that the power consumption by the deflector can be reduced and the amount of heat generated can be reduced. Can be lowered. In addition, the motor constituting the deflector can be reduced, and material consumption can be reduced.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a diagram schematically showing an example of the overall configuration of a multi-beam optical scanning device including a light source device of the present invention as viewed from the main scanning direction. Note that the holding parts of each optical element are omitted.
A light source 1A composed of a vertical cavity surface emitting laser array (VCSEL) having a plurality of light emitting points arranged two-dimensionally, and a coupling lens 2A (first imaging optical system) that condenses the divergent light beam from the light source 1A ) And a combination of the coupling lens 2B that collects the divergent light beam from the light source 1B are integrally supported by a support member (not shown) to form the light source unit 12.

  Details of the structure of the light source unit 12 and its peripheral part will be described. In the light source unit 12, the light source 1A and the light source 1B are fixed to aluminum die-cast holders 101A and 101B (not shown), and each holder is screwed from the back side to a common support member 102 (not shown). Fixed. The holders 101 </ b> A and 101 </ b> B may be configured to sandwich and hold the light sources 1 </ b> A and 1 </ b> B between the plate members through screws from the back side, or may be configured to press-fit each into the mating holes.

  The coupling lenses 2A and 2B couple the divergent light beams of the corresponding light sources 1A and 1B, align the positions in the lens optical axis direction so as to be in any state of the parallel light beam, the convergent light beam, and the divergent light beam. UV curing adhesive is applied to the gap between the V-groove or U-groove support portions 103A and 103B (not shown) formed on the support member 102 (or the clearance around the lens and support portion contact surface). And fixed. Here, the holders 101A and 101B and the support member 102 may be integrally formed as one component.

  The light source unit 12 engages the cylindrical portion 104 (not shown) formed on the support member with the mating hole 106 from the back side of the holding member 105 (not shown), and puts the cylindrical portion on each support member. The formed positioning portion is brought into contact with the reference, and is fixed from the front side of the holding member 105 through a screw. Here, the support member 102 is configured to be rotatable at the center of the cylindrical portion 104 and fixed at an arbitrary position. Thereby, the arrangement of the light beams emitted from the support member can be tilted.

The holding member 105 configured as described above 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 driving circuit of a surface emitting laser array as a light source is formed is fixed to a support 110 (not shown), and a semiconductor laser lead is soldered to make a circuit connection.
The above is the description of the light source device.

  In the light source unit 12, a plurality of light beams emitted from the light source 1 </ b> A have their light beam widths restricted by the aperture stop 3 </ b> A and are deflected by a cylindrical lens 5 (second image forming optical system) that is a line image forming optical system (polygon). In the vicinity of the deflecting / reflecting surface 6A of the scanner), the light is condensed into a long line in the main scanning direction.

  The deflector 6 rotates at a constant angular velocity about the rotation shaft 6B, and deflects the incident light beam at a constant angular velocity. Between the deflector 6 and the scanned medium 9, a third imaging optical system 7 (scanning optical system: a two-lens configuration in the figure, but the number is not limited, and a reflection optical system may be used). The light beam 8A deflected by the deflecting / reflecting surface 6A forms a light spot 10A on the scanned medium 9. Actually, since the light source 1A is composed of a surface emitting laser array, a plurality of light beams are simultaneously deflected by the deflecting / reflecting surface 6A to form a plurality of light spots on the scanned medium. This is shown by one light beam and a light spot. The light spot 10A optically scans the scanned medium 9 in the direction of the arrow in the figure by the rotation of the deflector 6 (in the direction of the arrow in the figure).

  Similarly, the width of light beams emitted from the light source 1B is restricted by the aperture stop 3B, and the deflector 6 (polygon scanner) is formed by the cylindrical lens 5 (second image forming optical system) which is a line image forming optical system. ) In the vicinity of the deflecting reflection surface 6A. Here, the aperture stops 3A and 3B may be separate bodies or may be formed integrally.

  The light beam 8B deflected by the deflecting and reflecting surface 6A forms a light spot 10B on the scanned medium 9. Also here, since the light source 1B is composed of a surface-emitting laser array, a plurality of light beams are optically scanned, but this is represented by a single light beam and a light spot as representative. The light spot 10B optically scans the scanned medium 9 in the direction of the arrow in the figure by the rotation of the deflector 6 (in the direction of the arrow in the figure).

  The light beam emitted from the light source 1A and the light beam emitted from the light source 1B are configured to intersect in the vicinity of the deflecting / reflecting surface 6A. The light beam emitted from the light source 1B is deflected and scanned with the deflector 6 being half the angle φ (φ / 2) formed by the light beams emitted from the light sources 1A and 1B with respect to the light beam emitted from the light source 1A. Configure. With this configuration, the light beams 8A and 8B emitted from the light sources 1A and 1B reflected by the deflecting and reflecting surface 6A can have substantially the same optical path in the third imaging optical system that is a scanning optical system, Thereby, the tilting of the imaging image plane of the scanning light beam on the surface to be scanned can be reduced, and the deterioration of the imaging performance (field curvature, magnification error, etc.) of each light spot can be prevented. In other words, when projected onto the main scanning plane, the center lines of a plurality of emitted light beams from the respective light sources of the light source unit 12 are arranged and configured so as to intersect in the vicinity of the deflection reflection surface 6A of the deflector.

  The light source unit 12 rotates a spatial center line 14 (or an axis substantially parallel to 14) of each exit axis passing through the vicinity of the intersection of the center lines (exit axes) of a plurality of exit light beams from the light sources 1A and 1B. The shaft is rotatable. Thereby, the arrangement of the light beams emitted from the respective light source units can be tilted.

  The synchronization detection optical system 11 deflects the light beam deflected by the deflector 6 to the synchronization detection sensor 11-1 including a photodiode after passing through the mirror 11-3 and the synchronization detection imaging element 11-2. Guide the luminous flux. Then, when the light beam passes over the synchronization detection sensor 11-1, a synchronization signal is generated, is processed by a synchronization circuit (not shown), and a writing start signal is transmitted after a certain timing. The certain timing here is the time from the detection position of the synchronization detection sensor 11-1 to the writing start position (however, the light source does not emit light during this period).

  The synchronization detection imaging element 11-2 may be a lens having power (refractive power) only in the sub-scanning direction, a lens having power only in the main scanning direction, or a lens having power in both main and sub directions. Further, as the synchronization detection imaging element 11-2, a curved mirror having power may be used instead of the lens. In addition, the synchronization detection optical system 11 is configured by using the mirror 11-3 with the above-described power and guiding it directly to the synchronization detection sensor 11-1 without using the synchronization detection imaging element 11-2. May be. The above is the description of the optical scanning device.

  FIG. 2 shows a configuration example in which two light source sections 12 shown in FIG. 1 are combined using light beam combining means, and the number of light beams scanned on the scanned surface 9 is further increased.

  In the first light source unit 12, a plurality of light beams emitted from the light source 1A-1 have their light beam widths restricted by the aperture stop 3A-1, and are transmitted (transmitted) through the beam combining prism 4 which is a light beam combining unit. A cylindrical lens 5 (second imaging optical system) that is an image optical system collects light in the vicinity of the deflecting reflection surface 6A of the deflector 6 (polygon scanner) in the form of a long line in the main scanning direction.

  The same applies to the light beam emitted from the light source 1B-1 (through the beam combining prism 4 (transmission)), and the deflector 6 (polygon scanner) by the cylindrical lens 5 (second imaging optical system) which is a line image imaging optical system. Near the deflecting / reflecting surface 6A is condensed in a line shape long in the main scanning direction.

  The center lines of the plurality of emitted light beams emitted from the light source 1A-1 and the center lines of the plurality of emitted light beams emitted from the light source 1B-1 prevent deterioration of the imaging performance of each light spot on the scanned surface. It is configured to intersect in the vicinity of the deflecting and reflecting surface 6A.

  Similarly, in the second light source unit 13, the luminous flux emitted from the light source 1 </ b> A- 2 is regulated by the aperture stop 3 </ b> A- 2, and is reflected (reflected) via the beam synthesis prism 4. A cylindrical lens 5 (second imaging optical system) that is a system condenses in the vicinity of the deflecting reflection surface 6A of the deflector 6 (polygon scanner) in a linear shape that is long in the main scanning direction. The same applies to the light beam emitted from the light source 1B-2.

  Similarly to the light source unit 12, in order to prevent deterioration of the imaging performance of each light spot on the scanned surface, the center lines of a plurality of emitted light beams emitted from the light source 1A-2 and the light source 1B-2 are emitted. The center lines of the plurality of emitted light beams are configured to intersect in the vicinity of the deflecting / reflecting surface 6A.

  The light source unit 12 passes through the vicinity of the intersection of the center lines (exit axes) of the plurality of emitted light beams from the light sources 1A-1 and 1B-1, and is substantially parallel to the spatial center line 14 (or 14) of each exit axis. The shaft is configured to be rotatable about the rotation axis.

  Similarly, the light source unit 13 also rotates a spatial center line 15 of each exit axis (or an axis substantially parallel to 15) that passes near the intersection of the center lines (exit axes) of a plurality of emitted light beams from the respective light sources. The shaft is rotatable. Thereby, the arrangement of the light beams emitted from the respective light source units can be tilted.

  Each light beam deflected by the deflecting / reflecting surface 6A forms a light spot on the scanned medium 9, and the light spot moves on the scanned medium 9 in the direction of the arrow in the figure by the rotation of the deflector 6 (the direction of the arrow in the figure). Light scan.

  The beam combining prism 4 which is a light beam combining means has a polarization separation film 4A, the emitted light beam from the light source unit 12 is transmitted through the polarization separation film 4A, and the emitted light beam from the light source unit 13 is reflected by the polarization separation film 4A. Then, it is configured to emit from the beam combining prism 4.

  As disclosed in Japanese Patent Application Laid-Open No. 9-236763 (Patent Document 2) and Japanese Patent Application Laid-Open No. 11-23988 (Patent Document 1), the light flux from the light source unit 13 is conventionally just before entering the beam combining prism 4. A half-wave plate is disposed on the polarizing plate, and the light flux from each light source unit is synthesized by changing the polarization direction in the polarization separation film 4A by 90 ° and transmitting or reflecting the light. This is because the edge-emitting semiconductor laser (LD) that has been used as a conventional light source has different light beam divergence angles in the direction perpendicular to the active layer of the LD, and therefore the polarization direction of the light source LD. Is not able to be rotated by 90 ° in each light source section, and will be described below.

  FIG. 3A is a diagram for explaining the divergence state of the light beam emitted from the semiconductor laser (LD). When the electrons resonate inside the semiconductor laser 16 and reach an energy level, the light emission point 17b of the active layer 17a Laser light is emitted. Due to diffraction at the light emitting point 17b, the laser beam has a radiation angle different between a direction perpendicular to the active layer and a horizontal direction, and the laser beam is emitted in an elliptical intensity distribution.

  Therefore, when the LD, which is the light source, is rotated by 90 °, each light beam that irradiates the aperture stop 23 has an intensity similar to that of the light beams 24 and 25 with respect to the aperture diameter of the aperture stop 23, as shown in FIG. The direction of the distribution ellipse is rotated 90 °. As a result, the relationship between the light beams 24 and 25 with respect to the aperture stop 23 is different, resulting in a difference in the light amount and beam spot diameter of the light spot on the scanned surface of each light beam, which causes deterioration in image quality.

  In contrast, a vertical cavity surface emitting laser array (VCSEL) having a plurality of light emitting points arranged two-dimensionally is arranged on the substrate surface of the surface emitting laser array 20 as shown in FIG. From the light emitting points (21a to 21d) provided, the laser light is emitted in a substantially circular intensity distribution. As a result, as shown in FIG. 4B, the intensity distribution of the light beam 26 that irradiates the aperture stop 23 becomes substantially circular with respect to the aperture diameter of the aperture stop 23, and therefore the intensity distribution is influenced by the polarization direction of the laser. I do not receive it. However, since the positions of the light emitting points are different, the directions of the principal rays of the light beams emitted from the coupling lens 2 are different as shown in FIG. For this reason, depending on the arrangement position of the aperture stop 3, a difference occurs in the irradiation state of each light beam to the aperture stop, and the difference in the amount of light spot and the beam spot diameter on the scanned surface of each light beam described above occurs. As a result, the image quality deteriorates.

  Therefore, by arranging the aperture stop 3 at the focal position S of the coupling lens, the irradiation state of the aperture stop 3 for each light beam becomes equal, and the above-described problem can be solved.

  A vertical cavity surface emitting laser array (VCSEL) having a plurality of light emitting points arranged two-dimensionally has a uniform polarization direction. By doing so, the beam can be synthesized by the beam synthesis prism 4. Further, by changing the polarization direction of the light beam incident on the beam combining prism 4 by 90 ° between the light transmitting side and the light reflecting side, a half-wave plate that is conventionally required for beam combining is unnecessary. Thus, by simplifying the configuration of the beam combining prism, the cost of the parts can be reduced.

  Since the emitted light beam from the light source unit 12 and the emitted light beam from the light source unit 13 are shifted in polarization direction by 90 degrees, transmission or reflection characteristics with respect to an incident angle (or reflection angle) to each optical element after the beam combining prism 4 Therefore, there is a difference in the amount of irradiated 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 appears as an unevenness in the density of the output image, particularly in a color image output machine, and causes deterioration in image quality. As a method for reducing the unevenness in the amount of light, a quarter wavelength plate is disposed immediately after the beam combining prism 4 and the polarization direction of the light beam is rotated by 45 degrees.

  FIG. 6 shows an example of a light source device having another configuration using a beam combining prism which is a light beam combining means. The light source units 112 and 113 are held by the holding member 111, and light beams 112 </ b> A and 112 </ b> B are emitted from the light source unit 112, and light beams 113 </ b> A and 113 </ b> B are emitted from the light source unit 113. Since the light source is composed of a surface emitting laser array, a plurality of light beams are emitted at the same time.

  The beam combining prism 27 has a polarization separation film 27B, and the light beam emitted from the light source unit 112 is transmitted through the polarization separation film 27B. The polarization direction of the surface emitting laser array of the light source unit 113 is assembled in a state of being rotated by 90 degrees with respect to the polarization direction of the surface emitting laser array of the light source unit 112, and the emitted light beam from the light source unit 113 is combined with the prism surface 27A and the polarization separation film. The beam is sequentially reflected by 27B and emitted from the beam combining prism 27.

  With this configuration, the light source units 112 and 113 can be arranged on the same plane, so that a single drive board for driving the surface emitting laser array as the light source can be configured. The configuration can be simplified. Note that the configuration shown in FIG. 6 may be a configuration viewed from the main scanning direction or a configuration viewed from the sub-scanning direction.

  In addition, with such a configuration, each light source unit is held close to the common holding member 105, and the influence of environmental fluctuations due to temperature fluctuations and the like becomes substantially equal, and the optical characteristics (scanning pitch and connection). The influence on the image position fluctuation) can be reduced. 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.

A configuration example of the irradiation position of the light beam emitted from each light source on the surface to be scanned will be described with reference to FIG.
FIG. 7 is a diagram schematically showing the irradiation position on the surface to be scanned of the luminous flux emitted from the surface emitting laser array as a light source. FIG. 7A shows an example in which the light spots by the light sources 1A ′ and 1B ′ are arranged alternately (staggered) as scanning lines. In this configuration, the light fluxes emitted from one light source are complemented by the light fluxes emitted from another light source.

In such a configuration, when the interval between the light emitting points cannot be reduced due to a droop problem or a crosstalk problem, the scanning pitch on the surface to be scanned is made narrower by combining a plurality of light sources as described above ( (Narrow pitch) and higher density optical writing becomes possible.
FIG. 7B shows an example in which the surface to be scanned is optically scanned with the light beam emitted from the next light source following the light beam emitted from one light source.

  As another configuration example, there is a method called an interlaced scanning method (interlace scanning method). As disclosed in Japanese Patent No. 2508871 and Japanese Patent No. 2939813, this is a method of filling a space between light beams by a plurality of scans, and writing with higher density than the method of FIG. Although it becomes possible, there is a problem that a large amount of memory is required for storing line data.

  The example of FIG. 7 is an example in which two surface emitting laser arrays as light sources are combined, but the same applies to the case where more are combined.

  In the sub-scanning direction, the positional relationship between each light emitting point of the surface emitting laser array as a light source and the relative positional relationship between each light spot on the scanned medium are between the light source and the scanned medium. The scanning magnification of the imaging system (coupling lens, cylindrical lens 5 and third imaging optical system 7 in the example of FIG. 1) in the sub-scanning direction is determined according to β, and scanning of each scanning line on the scanned medium The interval (scanning pitch) is set to a desired value.

  The above embodiment is an example in the case where two sets of a surface emitting laser array as a light source and a coupling lens (first imaging optical system) are combined in one light source unit. Also good. For example, in FIG. 6, one or both of the light source units 112 and 113 may be configured as three light sources.

  Similarly, the above embodiment is an example in which two light source units are combined as a light source device, but a light source device may be configured by combining more light source units. Conversely, one of the light source units combined by the beam combining prism as the beam combining unit may be a light beam from one light source, and a light beam from the other light source unit may be a light beam from a plurality of light sources.

  In this way, by configuring a light source unit using a plurality of light sources and further combining a plurality of light source units, the number of light beams scanned on the scanned medium 9 can be increased. As a result, the output speed of the image forming apparatus equipped with the writing optical system can be improved. Conversely, if it is not necessary to change the output speed, the rotation speed of the deflector can be reduced, and a writing optical system that takes into consideration the environment, such as power consumption and heat generation, should be constructed. Is possible.

  FIG. 8 is a view for explaining an image forming apparatus 30 on which the scanning optical system of the present invention is mounted. An original 31 is placed on a contact glass 32, illuminated by a lamp 33, and an image of the irradiated original is guided to a scanner lens block 34 by a mirror and processed as image data by a CCD. Data is transferred to the light beam scanning device 36, and the LD is repeatedly turned on and off based on the image signal, and the light spot scans on the photosensitive drum 46. The photosensitive member charged by the charger 40 is optically scanned to form an electrostatic latent image, developed as a toner image by the developing unit 37, and the paper is guided from the paper supply tray 38 to the photosensitive member by the paper supply roller 39, The image is transferred by the transfer roller 45, fixed by the fixing device 41, and discharged to the paper discharge tray 42 by the paper discharge roller 44. The photoreceptor 46 is subjected to charge removal and cleaning by the charge removal / cleaner 43, and the process from charging is repeated again.

  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.

  A color image capable of high-speed output can be obtained by incorporating the light source unit or the optical scanning device of the present invention into a color image forming apparatus in which a plurality of photosensitive drums are arranged and color toner images are superimposed to form a color image. A forming device can be formed.

  Furthermore, 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, a single image forming apparatus processes the output from a plurality of devices. An information processing system that can do this can be formed. In addition, if multiple image forming devices are connected to the network, the status of each image forming device (the degree of job congestion, whether the power is on, whether it is broken, etc.) can be known from each output request. Thus, it is possible to select and output an image output device that is in the best condition (best suited to the user's wishes).

  As described above, according to each embodiment of the present invention, since the present invention relates to a multi-beam writing optical system that optically scans a scanned medium with a plurality of light beams, the light beams from one light emitting point are scanned on the scanned medium. The rotational speed of the deflector can be reduced compared to the case of optical scanning. Thereby, the power consumption by a deflector can be reduced and the emitted-heat amount can also be reduced. In addition, the motor constituting the deflector can be reduced, and material consumption can be reduced.

  Further, according to the embodiment of the present invention, the number of light beams for optical scanning on the scanned medium can be increased, and the output speed of the image forming apparatus can be increased.

  In addition, according to the embodiment of the present invention, it is possible to reduce the separation of each light beam on the deflection reflection surface and to reduce the deflection reflection surface, thereby reducing the deflector. The tilt of the imaging image plane of the scanning light beam on the surface to be scanned can be reduced, and the deterioration of the imaging performance (field curvature, magnification error, etc.) of each light spot can be prevented.

  Further, according to the embodiment of the present invention, the influence of environmental fluctuations due to temperature fluctuations can be made substantially equal, and the influence on optical characteristics (scanning pitch and imaging position fluctuations) can be reduced.

  Further, according to the embodiment of the present invention, a multi-beam light source unit utilizing the advantages of the surface emitting laser can be configured.

  Further, according to the embodiment of the present invention, the half-wave plate is not necessary.

  Further, according to the embodiment of the present invention, an optical scanning device, an image forming device, and a color image forming device capable of multi-beam writing can be formed.

  As mentioned above, although the Example of this invention was described, it is not limited to the said Example, A various deformation | transformation is possible in the range which does not deviate from the summary.

  The present invention can be applied to a laser printer, a laser copying machine, a laser fax machine, a printing machine and the like equipped with an optical writing optical system.

It is a figure which shows the structure of the multi-beam optical scanning apparatus which concerns on Example 1 of this invention. It is a figure which shows the structure of the multi-beam optical scanning apparatus which concerns on Example 2 of this invention. It is a figure which shows the divergence state of the light beam which concerns on Example 2 of this invention. It is a figure which shows the intensity distribution state of the light beam which concerns on Example 2 of this invention. It is a figure which shows the emission direction of the light beam which concerns on Example 2 of this invention. It is a figure which shows the structure of the light source device which concerns on Example 3 of this invention. It is a figure which shows the structure of the irradiation position of the light beam which concerns on Example 4 of this invention. It is a figure which shows the structure of the image forming apparatus which concerns on Example 5 of this invention.

Explanation of symbols

1A, 1B Light source 2A, 2B Coupling lens 3A, 3B, 23 Aperture stop 4, 27 Beam combining prism 4A, 27B Polarization separation film 5 Cylindrical lens (second imaging optical system)
DESCRIPTION OF SYMBOLS 6 Deflector 6A Deflection reflective surface 6B Rotating shaft 7 3rd imaging optical system 8A, 8B, 24, 25 Light beam 9 Scanning medium 10A, 10B Light spot 11 Synchronization detection optical system 11-1 Synchronization detection sensor 11-2 Synchronization detection Imaging element 11-3 Mirror 12, 13 Light source section 14, 15 Center line 17a Active layer 17b, 21a, 21b, 21c, 21d Light emitting point 20 Surface emitting laser array 27A Prism surface 30 Image forming apparatus 31 Document 32 Contact glass 33 Lamp 34 Scanner lens block 35 Image data 36 Multi-beam optical scanning device 37 Developer 38 Paper feed tray 39 Paper feed roller 40 Charger 41 Fixing device 42 Paper discharge tray 43 Static elimination / cleaner 44 Paper discharge roller 45 Transfer roller 46 Photosensitive drum 111 Holding member 112, 113 Light source 11 A, 112B, 113A, 113B light beam

Claims (4)

In an optical scanning device that guides a light beam from a light source to a deflector, the light beam deflected by the deflector forms a light spot on a scanned medium by a scanning optical system, and performs deflection scanning.
The light source is a vertical cavity surface emitting laser array in which a plurality of light emitting points that can be independently modulated are two-dimensionally arranged,
A light source device is configured by combining a plurality of combinations of the light source and a coupling lens for coupling a divergent light beam emitted from the light source,
The light beams emitted from a plurality of sets including the light source and the coupling lens are configured to be combined by a light beam combining unit that combines the light beams through an aperture stop that regulates the light beams,
The arrangement of the light emitting points of the plurality of light sources is the same, and at least one of the polarization directions of the plurality of light sources is 90 degrees different in polarization direction from the other light sources ,
An optical scanning device characterized in that a light intensity distribution of a light beam emitted from the light source is circular . The plurality of sets are integrally supported via a support member,
2. The optical scanning device according to claim 1, wherein when projected onto a main scanning plane which is a plane orthogonal to the rotation axis of the deflector, a plurality of emitted light beams intersect with each other. . Image forming apparatus including the optical scanning device according to claim 1 or 2. Color image forming apparatus including the optical scanning device according to claim 1 or 2.

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