JP2004286989A - Optical scanner and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical scanner and an image forming apparatus that maintain a relative arrangement relation between light beams corresponding to respective pieces of color image information despite ambient temperature change and that can reduce the subscanning intervals of the light beams corresponding to respective colors. <P>SOLUTION: The optical scanner is equipped with: a deflection means 213 that performs main scanning by deflecting all together the light beams emitted from a plurality of light source means 201 to 204 and separated in the subscanning direction; a plurality of image forming means 218 that make the scanned light beams form an image on the corresponding surfaces to be scanned; and a housing means that holds the foregoing means. The plurality of light source means are arranged with the direction of each emitting axis in the same direction, and with the intervals at least in the main scanning direction specifically set at each emitting position. On the optical path of the light beams directed from each light source means to the deflection means 213, beam confluencing means 214 to 217 are installed and held by the housing means to bring the positions in the main scanning direction of the light beams successively closer to each other and make them incident on the deflection means 213. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device used in an optical writing system such as a digital copying machine and a laser printer, and an image forming apparatus using the same. In particular, the present invention relates to a multicolor image forming a color image by superposing a plurality of color toner images. The present invention relates to an optical scanning device suitable for a forming apparatus and an image forming apparatus using the same.
[0002]
[Prior art]
2. Description of the Related Art In an image forming apparatus using an electrophotographic process called a Carlson process, an electrostatic latent image is formed on the surface of a rotating drum according to the rotation of a photosensitive drum, developed with toner, and the toner image is transferred to transfer paper. By doing so, an image is formed. A plurality of the photoconductor drums are arranged, an electrostatic latent image is formed on the surface of each photoconductor drum according to an image information signal for each color component, and is developed with a corresponding color toner. Thus, a color image can be formed. Such an image forming apparatus is referred to as a multi-color image forming apparatus, and an image forming section for each color including each photosensitive drum and an optical scanning device for writing an image on the photosensitive drum is referred to as an image forming station. In a multi-color image forming apparatus, the difference in the time from the latent image formation to the transfer due to the eccentricity and the variation in the diameter of the photosensitive drum, the difference in the photosensitive drum interval corresponding to each color, the drive speed of the transfer body, for example, the transfer belt Due to the fluctuation or meandering of the toner, or the speed fluctuation or meandering of the conveyor belt that conveys the recording paper as a transfer member, a registration shift of each toner image occurs, which causes a color shift or a color change, thereby deteriorating the image quality. Also, in an optical scanning device that forms a latent image on a photosensitive drum, if the latent image forming position on each photosensitive drum is not accurately aligned, color shift or color change may occur.
[0003]
Conventionally, this registration deviation is not distinguished from that of the optical scanning device and that of the device other than the optical scanning device, and the sub-scanning position is periodically detected between jobs and the like based on the registration deviation detection pattern recorded on the transfer body, and the writing start timing. (For example, see Patent Literature 1 and Patent Literature 2).
[0004]
Also, regarding the processing error and thermal deformation of the scanning lens itself, the deviation of the beam incident height to the scanning lens, and the bending of the scanning line caused by the so-called eccentricity, the scanning lens having the power in the sub-scanning direction is mainly scanned. An example in which correction is performed by moving along a direction (for example, see Patent Document 3), an example in which an optical axis of a scanning lens is shifted with respect to a light beam (for example, see Patent Document 4), in a plane orthogonal to a scanning surface There has been proposed a method of correcting by means such as tilting a scanning lens (for example, see Patent Document 5). In these methods, for example, it is possible to detect the amount of scan line bending between jobs and the like, and to correct this in accordance with the detected amount of bending.
[0005]
On the other hand, as a method that can reduce the deviation without such correction, as the image forming means, a scanning lens common to each color beam and having no converging power in the sub-scanning direction, and a scanning lens for each color beam individually (For example, see Patent Documents 6 and 7). As described above, by scanning the light beam corresponding to the image information of each color in the same direction, it is possible to reduce the influence of a processing error for each scanning lens and a change in refractive index due to non-uniform temperature, and to reduce a resist deviation. Are known.
[0006]
In this case, in order to collectively scan a plurality of light beams corresponding to the image information signals of the respective colors on the same surface of the polygon mirror as the deflecting means, optical beams from a plurality of light source means are aggregated and incident on the polygon mirror. Examples of means have been proposed (see, for example, Patent Documents 8 and 9), and examples of separation optical means having light source means having a plurality of light emitting sources and leading to each scanned surface after being deflected have been proposed. (For example, see Patent Documents 10 and 11).
[0007]
[Patent Document 1]
Japanese Patent No. 3049606
[Patent Document 2]
Japanese Patent No. 3078830
[Patent Document 3]
JP-A-2002-148551
[Patent Document 4]
JP-A-11-64758
[Patent Document 5]
JP-A-64-52116
[Patent Document 6]
JP-A-2-250020
[Patent Document 7]
JP-A-7-43627
[Patent Document 8]
JP 2001-296492 A
[Patent Document 9]
JP-A-9-179047
[Patent Document 10]
JP 2000-330049 A
[0008]
[Problems to be solved by the invention]
As described above, in the multi-color image forming apparatus in which a plurality of image forming stations are arranged along the transfer direction of the transfer body and the images corresponding to the respective colors are superimposed, the image is formed at each station according to the image information corresponding to the respective colors. Unless the registration positions of the latent images at the transfer position are properly adjusted, color registration or color change may occur.
[0009]
However, in the optical scanning device, even if the scanning position deviation between the stations, which causes the registration deviation, is adjusted before the job, if the number of prints in one job increases, the above-described housing may be changed with the temperature change. Since the position of incidence on the scanning lens fluctuates due to the deformation, the fluctuation of the scanning position in the period until the next correction is inevitable. Of course, even within one job, it is possible to interrupt printing and make corrections in the middle, but it takes time to correct not only the writing position of the main scanning and sub-scanning of the scanning line but also the bending of the scanning line. . Furthermore, in order to detect the adjusted result, it is necessary to record the registration shift detection pattern on the transfer body, and during that time, the apparatus is in a state where recording is not possible, and the printing waiting time is prolonged, thereby impairing the work efficiency. Further, if the number of corrections is large, the amount of wasteful toner consumption increases, so that it is desirable to avoid frequent corrections. Therefore, it is a problem how to keep the scanning position stable even if there is an environmental change.
[0010]
On the other hand, in order to suppress the heat generated by the polygon motor, which is one of the causes of environmental changes, it is necessary to reduce as much as possible the windage loss due to the wind breaking at the edge of the polygon mirror which is a high-speed rotating body. Since windage increases in proportion to the thickness of the polygon mirror, it is desirable to minimize the sub-scanning interval of each color beam and to reduce the thickness of the polygon mirror as much as possible, thereby reducing power consumption.
[0011]
The present invention focuses on an incident position shift to a deflecting unit such as a polygon mirror in a sub-scanning direction, which is a main cause of a scan position shift and a bending, and there is a change in a condition over time, especially a change in an environmental temperature. Therefore, while maintaining the relative positional relationship between the light beams corresponding to each color image information, the sub-scanning interval of the light beams corresponding to each color is minimized, and the polygon mirror is thinned to suppress the heat generated by the polygon motor. An object of the present invention is to provide an optical scanning apparatus and an image forming apparatus capable of obtaining a stable color image without color shift or color change accompanying a printing operation by making it difficult for an environmental change to occur. It is another object of the present invention to provide an optical scanning device and an image forming apparatus that suppress power consumption and wasteful toner generation due to correction of color overlay accuracy such as registration misregistration and maintain the environment. Further, the purpose of each claim is as follows.
[0012]
According to the inventions of claims 1 to 3, 5 and 6, the mounting orientations of the respective color light sources are made uniform, and the deviation of the light beam emission directions due to the environmental temperature change is caused similarly, so that the relative distance between the respective light beams is increased. It is an object of the present invention to provide an optical scanning device capable of maintaining a good positional relationship.
[0013]
According to a fourth aspect of the present invention, the distance between the respective color beams on the polygon mirror is reduced, and the light beam can be surely separated after the light beam is deflected by the deflecting means. An object is to provide an optical scanning device capable of reducing a temperature change.
[0014]
According to the present invention, even when a light source having a plurality of light emitting sources is used, the scanning line pitch on the surface to be scanned can be adjusted for each light source, so that high-speed and high-density image recording can be performed. It is an object to provide an optical scanning device that can be adapted.
[0015]
According to the tenth to thirteenth aspects of the present invention, each light source can be arranged in the same plane, so that each light source can be easily integrated into a single unit, and each light source can be shared by a common driving circuit. It is an object of the present invention to provide an optical scanning device that can be directly mounted on a substrate to reduce the number of components, reduce the number of work steps such as wiring connection, and improve productivity and maintainability.
[0016]
According to a fourteenth aspect of the present invention, by adopting the optical scanning device according to any one of the first to thirteenth aspects as a unit for executing an image writing or exposure process, the position of a scanning line associated with a change in environmental conditions is obtained. It is an object of the present invention to provide an image forming apparatus which is suitable for colorization, high-speed operation, and high-density operation by reducing displacement and bending.
[0017]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of an optical scanning device and an image forming apparatus according to the present invention will be described with reference to the drawings.
[0018]
FIG. 1 shows an embodiment in which an optical scanning device and a writing device for writing an image on a photosensitive member by the optical scanning device are arranged in one direction for four stations. FIG. 2 is a sectional view thereof. 1 and 2, four photosensitive drums 101, 102, 103, and 104 are arranged along the moving direction of the transfer belt 105, and transfer toner images of different colors sequentially formed on the respective photosensitive drums to the transfer belt. It is configured such that a color image can be formed by superimposing and transferring the image on the image 105. In this color image forming apparatus, each optical scanning device is integrally formed in an appropriate housing means, and all the light beams are deflected and reflected by the same deflection reflecting surface of a single polygon mirror 213 to scan. I have.
[0019]
The semiconductor lasers 201, 202, 203, and 204 as a plurality of light source means are arranged at equal intervals on a straight line inclined by γ from the main scanning corresponding direction so that the light emitting source positions are on the same plane. The emitted light beams are converted into parallel light beams by the coupling lenses 205, 206, 207, and 208, respectively. In the path of each light beam transmitted through the coupling lens, cylinder lenses 209, 220, 211, and 212 having one surface being a flat surface and the other surface having a common curvature in the sub-scanning direction are arranged. . Each light beam is arranged so that the light path length to the deflection point of the polygon mirror 213 becomes equal by passing through the cylinder lens. Each light beam is converged only in the sub-scanning direction by the cylinder lens, and a long line image is formed in the main scanning direction near the deflecting reflection surface of the polygon mirror 213.
[0020]
Reflecting mirrors 214, 215, 216, and 217 as beam merging means are arranged between the cylinder lenses and the polygon mirror 21 on the path of the light beam transmitted through each of the cylinder lenses 209, 220, 211, and 212. Have been. These reflecting mirrors are arranged stepwise in accordance with the height position of each light beam so that each reflecting surface is parallel. The light beam from the semiconductor laser 201 is adjusted to the optical path toward the polygon mirror 213 by the reflection mirror 214, and the light beam from the semiconductor laser 202 is merged on the optical path by the reflection mirror 215 so that the position in the vertical direction is matched. The beam from the semiconductor laser 203 is merged on the optical path by the reflecting mirror 216 so that the position in the vertical direction is matched, and the light beam from the semiconductor laser 204 is aligned on the optical path by the reflecting mirror 217 in the vertical direction. It is configured to be joined. As described above, the reflection mirrors 214, 215, 216,... Are reflected such that the light beams are reflected in order from the side farthest from the polygon mirror 213, and are incident on the polygon mirror 213 with the main scanning directions of the beams overlapping in the vertical direction. 217 are arranged.
[0021]
When each light beam is emitted at a predetermined interval L in the sub-scanning direction, the interval S between the semiconductor lasers 201, 202, 203, and 204 is
L = S · sin γ = 5 mm
It is arranged to be. The respective emission axes are parallel, and this interval L is maintained even on the deflecting / reflecting surface of the polygon mirror 213, and the light enters from a direction perpendicular to the deflecting / reflecting surface, more precisely, from a direction perpendicular to the rotation center axis of the polygon mirror 213. Therefore, the polygon mirror 213 is formed thick in the direction of the rotation center axis.
[0022]
In the illustrated embodiment, the polygon mirror 213 is a six-sided mirror, and a circumferential groove is formed at a portion between light beams that does not contribute to the deflection and reflection of the light beam to a depth slightly smaller than the inscribed circle of the polygon mirror 213. The shape is provided so that windage loss can be further reduced. The thickness of one layer of the deflecting reflection surface is about 2 mm.
[0023]
When the polygon mirror 213 is rotationally driven, each light beam is deflected and reflected by each deflecting / reflecting surface, and an fθ lens 218 constituting a scanning image forming optical system is arranged on the path of the deflected light beam. lens 218 is common to each light beam, is formed to be thick like the polygon mirror 213, and has no converging force in the sub-scanning direction. lens 218 has a non-cylindrical surface shape with power in the main scanning direction so that a light beam moves at a constant speed on each photosensitive drum surface as the polygon mirror 213 rotates. lens 218 is provided for each beam, and a toroidal lens having a surface tilt correcting function of the polygon mirror 213 is provided on the path of each of the deflection light beams between the fθ lens 218 and the photosensitive drums 101, 102, 103, and 104. 219, 220, 221 and 222 are arranged. The toroidal lenses 219, 220, 221 and 222, together with the fθ lens 218, form each light beam into a spot image on the surface of the photosensitive drums 101, 102, 103 and 104, and apply the light beams to the four photosensitive drum surfaces. It constitutes an optical scanning means or an image forming means for simultaneously forming an electrostatic latent image.
[0024]
In each optical scanning unit, the light path length of each light beam from the polygon mirror 213 to the surface of the photosensitive drum is equal, and the incident positions and incident angles on the photosensitive drums arranged at equal intervals are equal. In this manner, a plurality of folding mirrors are arranged. The optical path of each optical scanning means will be described. The light beam emitted from the semiconductor laser 201 is deflected and reflected by the uppermost layer of the polygon mirror 213 and is reflected by the return mirror 223 after passing through the fθ lens 218. Then, the light is guided to the photosensitive drum 101 via the toroidal lens 219, and a yellow image is formed on the surface of the photosensitive drum 101 as first optical scanning means.
[0025]
The light beam emitted from the semiconductor laser 202 is deflected and reflected by the second-stage deflecting and reflecting surface of the polygon mirror 213, passes through the fθ lens 218, is reflected by the turning mirror 224, passes through the toroidal lens 220, and is turned by the turning mirror. The light is reflected at 227 and guided to the photosensitive drum 102, and forms a magenta image on the surface of the photosensitive drum 102 as a second optical scanning unit.
[0026]
The light beam emitted from the semiconductor laser 203 is deflected and reflected by the third-stage deflecting and reflecting surface of the polygon mirror 213, passes through the fθ lens 218, is reflected by the turning mirror 225, passes through the toroidal lens 221 and passes through the turning mirror. The light is reflected at 228 and guided to the photosensitive drum 103, and forms a cyan image on the surface of the photosensitive drum 103 as third optical scanning means.
[0027]
The light beam emitted from the semiconductor laser 204 is deflected and reflected by the lowermost deflecting and reflecting surface of the polygon mirror 213, passes through the fθ lens 218, is reflected by the turning mirror 226, passes through the toroidal lens 222, and passes through the turning mirror 228. As a result, a black image is formed on the surface of the photosensitive drum 103 as fourth optical scanning means.
[0028]
Of these optical scanning devices, the folding mirrors 224, 225, and 226 constitute beam splitting means, and first split the beam from the semiconductor laser 204 that has been finally joined by the beam joining means along the beam flow. Further, the beam from the semiconductor laser 203 is sequentially branched, for example, in accordance with the arrangement order in the sub-scanning direction. In the illustrated embodiment, the reflection angle of each return mirror has the following relationship, and the entire optical path is routed to the lower side of the polygon motor 106, thereby reducing the size of the entire housing 105.
β1 <β2 <β3 <β4, β4-β1 <90 °
The four optical scanning means are housed in a single housing 110 as shown in FIG.
[0029]
The polygon motor 106 in the illustrated embodiment is of a dynamic pressure air bearing type. The dynamic pressure air bearing is provided by mounting a fixed shaft 108 erected on a base 107 fixed to a housing 110 and having a herringbone groove formed on the outer periphery thereof, and a cylindrical sleeve 109 formed by hollowing out the center of a polygon mirror 213. And the cylindrical sleeve 109 of the rotary body is inserted into a fixed shaft 108. An annular magnet 111 is provided below the rotating body, and a polygon motor 106 is configured by the magnet 111 and a magnetic coil 112 facing the magnet on the outer side in the circumferential direction. The polygon mirror 213 is driven to rotate at a high speed together with the rotating body by switching and controlling the energization to the 112. The fθ lens and the toroidal lens are fixed at predetermined positions of the housing 110 by means such as bonding or pressing with a leaf spring.
[0030]
As shown in FIG. 2, each of the photoconductor drums 101, 102, 103, and 104 is disposed below the outside of the housing 110, and a dust-proof glass 234, 235, 236 and 237 are arranged. Each dustproof glass is mounted on a cover that covers the lower side of the housing 110. The first optical scanning means is provided with a synchronization detection sensor 230 that receives a light beam that is turned back by a part of the dustproof glass 234 on the scanning start side of the image recording area and receives the light beam. Based on the detection signal from the sensor 230, the timing of starting writing in the main scanning direction in each optical scanning unit is matched.
[0031]
Further, the transfer belt 231 is configured to be extended and rotated by three rollers including a driving roller and a driven roller, so that a toner image is sequentially transferred from each photosensitive drum. When transferring the toner images, the registration positions are adjusted according to the writing start timing in the sub-scanning direction, and the respective toner images are superimposed.
[0032]
As described above, the registration position is periodically adjusted, and detectors for reading the reference position of each image to be formed on the transfer belt 231 are provided at both ends in the width direction of the transfer belt. The detector includes an LED element 231 for illumination, a photo sensor 232 that receives light reflected from the transfer belt 231, and a pair of condenser lenses 233. Near the both ends in the width direction of the transfer belt 231, detection patterns composed of toner images of the reference color (yellow) and other colors (cyan, magenta, black) are formed in parallel. In the illustrated embodiment, a detection pattern of a toner image inclined by 45 ° from the main scanning direction is formed. This pattern is read, the amount of registration shift in the sub-scanning direction is calculated from the detection timing, and based on the detection result, the optical scanning means sets the deflecting reflection surface of the polygon mirror every other surface, that is, one scanning line pitch P. The writing timing in the sub-scanning direction is adjusted as a unit.
[0033]
FIG. 3 is a plan view showing a light source unit in the embodiment, and FIG. 4 is an exploded perspective view showing an example of a light source unit used in the light source unit. 3 and 4, a so-called semiconductor laser array in which two light emitting sources are monolithically formed at a pitch of several tens of μm is used as the semiconductor lasers 201, 202, 203, and 204 constituting a plurality of light source means. The respective semiconductor lasers are press-fitted and fixed to a common support member 301 by fitting the outer periphery of the package so as to be symmetrical with respect to the emission axis. The coupling lenses 205, 206, 207, and 208 are provided corresponding to the respective semiconductor lasers, and are provided in the semicircular grooves of the protrusion 302 formed with the semicircular grooves provided on the common support member 301 back to back. Fixed. Then, each coupling lens is aligned on the xy plane (a plane orthogonal to the emission axis) so that the optical axis coincides with each emission axis, and the z direction (the exit beam becomes a parallel light beam). It is fixed by aligning the position in the optical axis direction and filling the gap with the outer periphery of the lens with an ultraviolet (UV) curing adhesive.
[0034]
In the illustrated embodiment, the light sources are arranged such that the beams are emitted in parallel with an interval L of 5 mm in the sub-scanning direction. A cylindrical pedestal 304 is formed on the back side of the support member 301 by integral molding. The cylindrical pedestal 304 is fixed to the surface side of the printed circuit board 303 with screws, and is printed with each semiconductor laser fitting portion of the support member 301. A predetermined space is formed between the substrate 303 and the surface thereof. The lead terminals extending from the back surface side of each semiconductor laser are inserted into through holes of the printed circuit board 303, and are soldered to circuit patterns on the printed circuit board 303, whereby the light source unit 300 is integrally formed.
[0035]
The light source unit 300 is positioned with reference to a cylindrical projection 306 in an engagement hole provided in a wall surface 305 of a housing in which the above-described polygon mirror, fθ lens, and the like are held and housed, and a light beam emission axis. The light source unit 300 is integrally fixed to the housing by abutting an abutting surface 307 perpendicular to. As described above, the cylinder lenses 209, 20, 211, 212 and the reflection mirrors 214, 215, 216, 217 are arranged so as to satisfy the following conditions.
α1 = α2 = α3 = α4
ae = abf = acg = adh
[0036]
Here, the distance ΔL = ae−dh between the cylinder lenses increases as the distance between the semiconductor lasers increases, and a useless space is generated. However, the focal length of each cylinder lens 209, 20, 211, 212 is
f1>f2>f3> f4
By bringing ΔL closer to 0, it is also possible to align them on the same plane orthogonal to the emission axis. In this case, the lateral magnification 副 in the sub-scanning direction differs for each optical scanning means, and the beam spot interval on the photoconductor surface between the light emitting sources of the respective semiconductor lasers changes. By changing the inclination angle γ in the plane, the beam spot interval can be adjusted as shown in FIG.
[0037]
Now, assuming that the sub-scanning lateral magnification of the entire optical system including the coupling lens, the fθ lens, and the toroidal lens is ζ and the emission source pitch is d, the interval P between the beam spots 301 and 302 in the sub-scanning direction is
P = ζ · d · sinγ
By changing the inclination angle γ, a plurality of adjacent lines are simultaneously scanned in accordance with the pixel pitch P according to the recording density.
[0038]
In the embodiment, the light source unit corresponding to each color including the semiconductor laser and the coupling lens is a light source unit that is integrated. However, even if the light source units are individually configured, each light source unit is held when the light source unit is held in the housing. The same effect can be obtained if the direction of the emission axis is adjusted and the position of the plane orthogonal to the emission axis on which the light emitting source is arranged is made closer.
[0039]
FIG. 5 shows a supporting portion of the reflecting mirror in the beam merging means. Each reflection mirror 500 is installed on an L-shaped mounting portion 501 formed on the bottom surface of the housing, and the reflection mirror is pressed against a vertical surface by a leaf spring 502. The upward displacement of the reflection mirror is regulated by the bent end portion 503 of the leaf spring so that a part of the reflection mirror is not applied to the beam passing therethrough. By gradually changing the installation height H of each reflection mirror by the L-shaped mounting portion 501, the reflection mirror can be arranged according to the beam interval in the sub-scanning direction, and the pressing direction can be set to the same side of the housing. They can be aligned and supported in a similar manner.
[0040]
FIG. 15 shows an embodiment in which the reflection mirror in the beam merging means is formed integrally. The high-purity aluminum block is cut out stepwise to form four parallel surfaces, and these four surfaces are used as reflection mirrors 504, 505, 506, and 507. The light beam merging means made of the aluminum block is fixed to the housing by abutting the bottom surface thereof to the housing through the through holes 508 at both ends of the block.
[0041]
FIG. 6 is a configuration diagram of a light source unit in another embodiment, and shows an example in which a plurality of semiconductor lasers are provided for each color. FIG. 7 is a perspective view of the light source unit. The structure of the beam converging means is composed of reflecting mirrors 603, 604, 605, and 606 arranged so that the respective surfaces are parallel to each other, as in the above embodiment. The semiconductor lasers 607, 608, 611, 612, 615, 616, 619, 620 and the coupling lenses 609, 610, 613, 614, 617, 618, 621, 622 are each provided on the emission axis for each color scanning means. They are arranged symmetrically in the main scanning direction.
[0042]
As shown in the sectional view of FIG. 8, in the semiconductor laser as the light source means, the outer periphery of the package is fitted or press-fitted into each of the support members 623, 624, 625, 626. Each coupling lens is aligned with the semi-circular groove of the protrusion 637 formed with a pair of semi-circular grooves back to back in the optical axis direction so that the emitted beam becomes a parallel light beam, and is positioned on the outer periphery of the lens. Is filled and fixed with an ultraviolet (UV) curing adhesive. Each optical axis is inclined so as to be in a direction crossing each other with respect to the emission axis C. In the embodiment, the shape of the support member is designed so that this intersection position is near the deflection reflection surface of the polygon mirror.
[0043]
The support members 623, 624, 625, and 626 are formed at regular intervals in the base member 627 so that an interval L in the sub-scanning direction is a predetermined interval. , 629, 630, and 631, the cylindrical portions 635 of the respective support members are inserted, and a pair of flange portions 636 are positioned by abutting against a contact surface (base member back surface) orthogonal to the injection axis C to be formed on the flange portions. A screw is screwed into the screw hole from the front side of the base and fixed. At the time of this fixing, similarly to the above-described embodiment, the beam spot interval can be adjusted to the pixel pitch P according to the recording density by adjusting the amount of tilt with reference to the cylindrical portion. Further, the printed circuit board 632 on which the drive circuit is formed is mounted on a cylindrical pedestal 634 erected on the base member 627 by screw fixing, and the light source unit 600 is integrally configured. The light source unit is screwed by abutting the contact surface 638 against the wall surface of the housing. Each contact surface (the back surface of the base member) is formed such that the emission axes C are parallel to each other or in a direction intersecting the main scanning direction.
[0044]
As in the above embodiment, a semiconductor laser array having a plurality of light emitting sources may be used for each of the semiconductor lasers. By increasing the number of beams for each color scanning means by combining these, a higher speed and higher density can be achieved. It can be applied to various image recordings.
[0045]
FIG. 10 shows an embodiment in which the beam merging means is provided integrally with the light source unit. FIG. 11 is a sectional view in the main scanning corresponding direction. The beam converging means 701 includes a prism having a parallelogram cross section and a prism having a triangular cross section, and the joint surface 702 forms a polarization beam splitter. A λ / 2 plate 721 is attached to the beam incident surface on the parallelogram side, so that the polarization directions of the beams from the semiconductor lasers 703 and 704 are rotated by 90 °. The beams from the semiconductor lasers 703 and 704 are incident on the beam converging means 701, are reflected on the slope 707, are reflected on the bonding surface 702, and come close to the beams from the semiconductor lasers 705 and 706 transmitted in the main scanning direction. It is injected.
[0046]
The semiconductor lasers 703, 704, 705, and 706 corresponding to the respective colors are divided into two for every two colors. Is held in. In the present embodiment, the semi-circular grooves for joining the coupling lenses and the coupling lenses of the semiconductor lasers are coaxial so that the semiconductor lasers are arranged in the sub-scanning direction and the optical axes are parallel to each other. Designed. The support member abuts a pair of flange portions 723 against the base member 714 and is fixed by screws. The light-emitting sources are arranged in a staggered manner on an xy plane orthogonal to the emission axis, and the distance between the semiconductor lasers on each support member is 2L. A printed circuit board 716 on which a semiconductor laser drive circuit is formed is fixed to a cylindrical pedestal 717 erected on the base member 714 by screws.
[0047]
The beam converging means 701 is accommodated in the holder member 715, and is joined to the base member 714 by screws with the contact surface 724 abutting on the beam converging means 701, thereby integrally configuring the light source unit 700. The light source unit 700 is positioned on the housing wall surface with reference to the cylindrical protrusion 718, and is fixed by screws by abutting a contact surface 719 orthogonal to the emission axis. The contact surface 719 is parallel to the abutting surface of the flange portion 723 and the contact surface 724.
[0048]
In the present embodiment, the cylinder lens 720 has a plane side perpendicular to the emission axis aligned on the same plane, and the other side is adjacent to the sub-scanning direction at equal intervals and has a continuous cross-sectional shape. The respective curvatures are the same, and the focal lines are formed so as to be aligned on a plane orthogonal to the emission axis. Each beam is incident on a plane passing through the center of curvature of the corresponding lens unit, and the deflecting and reflecting surface of the polygon mirror The power is set to converge above.
[0049]
Next, a mechanism for correcting the inclination and the bending of the scanning line will be described. FIG. 12 shows a first embodiment of the present invention, in which a support portion of the toroidal lens 401 to the optical housing bottom surface 400 is shown. Each of the toroidal lenses 401 is opposed to each of the photosensitive drums, and is arranged on the bottom surface of the optical housing so that the optical axis direction and the sub-scanning direction are aligned. A projection 405 provided at the center of the box-shaped rib 402 is attached to the optical housing. The main scanning direction (longitudinal direction) is regulated by engaging with the formed concave portion 403, and the lower ends of the flange portions 404 provided at both ends are similarly engaged with the concave portion 406 to change the optical axis direction (transverse direction). Regulating. Further, the lower surface of the box-shaped rib 402 is set so that one of the main scanning directions is substantially at the center (first support point) in the sub-scanning direction, and the other is emitted from the incident side (second support point) in the sub-scanning direction. It is configured to receive at two points on the side (third support point), that is, a total of three points, and to press and support the plate spring 407 from above.
[0050]
In the embodiment, the second support point is positioned as a reference abutment by a protrusion 408 protruding from the bottom surface of the housing, and the third support point is provided with a shaft extending from the stepping motors 411 and 412 through the through holes 409 and 410 from the back surface. The tips 413 and 414 are directly abutted. In addition, the shaft is a built-in feed screw, and the protrusion amount expands and contracts.
[0051]
Here, when only the first support point is changed, the toroidal lens 401 rotates around the rotation axis connecting the second and third support points in a plane orthogonal to the optical axis as shown by the reference numeral γ. Can be adjusted. As shown in FIG. 14B, the focal line 422 is inclined according to the inclination of the bus 421 in the main scanning direction, and the scanning line is inclined. Further, as shown in FIG. 14A, when only the second support point is changed, as shown by reference numeral β, the toroidal lens 401 moves around the rotation axis connecting the first and third support points. The rotation can be adjusted in the sub-scan section including the optical axis, and the beam can be incident on a position where the amount of eccentricity from the generating line 422 differs in the main scanning direction according to the inclination of the curved surface, and the focal line 422 can be deflected. Thereby, the above-described warpage is intentionally generated and corrected so as to cancel the bending of the scanning line due to a processing error or an arrangement error of the optical element constituting the optical system, and the linearity of the scanning line can be improved. it can. In the embodiment, the adjusting mechanism is provided in the toroidal lens of the optical scanning means other than yellow. Although the rotation axis connecting the first and third support points is not exactly perpendicular to the optical axis, it is considered to be substantially perpendicular to the optical axis because it is sufficiently longer than the interval between the second and third support points. be able to.
[0052]
In FIG. 12, reference numerals 415 and 417 denote attachment portions of the folding mirrors 416 and 418, respectively. The mounting portions are provided on the bottom surface of the housing in pairs in the main scanning direction, and the reflection surface of the return mirror is pressed against the slope by the leaf spring 419 and supported. Further, the upward displacement is regulated by the bent end portion 420 of the leaf spring so that a part of the mirror is not applied to the beam passing above.
[0053]
Each of the folding mirrors 416 and 418 constituting the beam branching means can be arranged by providing the installation height h of the mounting portion stepwise, and supported by aligning the pressing direction of the leaf spring on the same side of the housing. You.
[0054]
Like the adjustment of the registration position, the adjustment of the inclination and the bending of the scanning line described above is periodically performed so as to adapt to the use environment of the image forming apparatus by using a preparation period before a print job or a standby period between jobs. Done in Based on the detection result of the detector, the scan line of each color is automatically corrected so as to be parallel to the reference yellow scan line and to be aligned with the direction of the bend, and the timing correction for writing the image described above. By combining with, the images recorded and formed in each station can be superimposed with high accuracy, and a high-quality color image without color shift can be formed.
[0055]
FIG. 13 shows an example of a color image forming apparatus equipped with the optical scanning device described above. In FIG. 13, a charger 902 for uniformly charging the surface of the photosensitive drum at a high voltage around the photosensitive drum 901, and a charged toner is adhered to the electrostatic latent image recorded by the optical scanning device 900 for visualization. And a cleaning case 905 for scraping and storing the toner remaining on the photosensitive drum 901. As described above, an image is simultaneously recorded on the photosensitive drum 901 by scanning a plurality of lines, that is, two lines in this embodiment, by scanning the deflecting reflection surface of the polygon mirror.
[0056]
The above-described image forming station has been described on behalf of one of the four juxtaposed stations. Four image forming stations are arranged side by side in the moving direction of the transfer belt 906. An image is formed on the photosensitive drum of each station by executing a well-known electrophotographic process of charging, exposure, development, transfer, cleaning, and fixing. However, in the transfer step in the illustrated embodiment, the yellow, magenta, cyan, and black toner images formed on the four photosensitive drums are sequentially transferred onto the transfer belt 906 in sequence at the same timing, and are superimposed to form a color image. An image is formed, and this color image is transferred to recording paper, so that a color image is formed on transfer paper. Each image forming station has basically the same configuration except for the toner color.
[0057]
The recording paper is supplied from a paper feed tray 907 by a paper feed roller 908, and is sent to the image position on the transfer belt 906 by a pair of registration rollers 909 in a timely manner, and a color image on the transfer belt 906 at a predetermined transfer position. Is transferred to the transfer paper. The transferred toner is fixed by a fixing roller 910, and the recording sheet is discharged to a discharge tray 911 by a discharge roller 912.
[0058]
In each of the embodiments described above, the plurality of light source units are integrally held by a common support member with their emission axes aligned in the same direction, and their emission positions are at least predetermined in the sub-scanning direction. It may be detachably held by the housing means so as to form an interval. By doing so, the mounting posture between the light sources can be accurately adjusted, even if there is a shift due to the assembly or replacement of the light source means, it can be corrected immediately, and even if there is an environmental change, the relative position of each light source can be corrected. Can be modified to maintain the correct posture.
[0059]
【The invention's effect】
According to the first aspect of the present invention, a deflecting unit that deflects light beams emitted from a plurality of light source units and is separated in the sub-scanning direction collectively to perform main scanning, and converts the scanned light beams into these light beams In an optical scanning device having a plurality of image forming means for forming an image on a surface to be scanned corresponding to the above, and a housing means for holding these means, the plurality of light source means are arranged such that the directions of their emission axes are aligned and each At least the intervals of the emission positions in the main scanning direction are arranged at a predetermined interval, and beam merging means is provided on an optical path of a light beam from each light source means to the deflecting means, and the beam merging means is provided by housing means. It is characterized in that it is held so that the position of the light beam in the main scanning direction is sequentially approached to be incident on the deflecting means. Thereby, when arranging the beams from the respective light sources in a line in the sub-scanning direction and deflecting the light beams, the distance between the light beams can be narrowed without depending on the size of the light source unit, and the mounting posture of the light source unit is aligned. Since they can be arranged, even if the attitude of each light source fluctuates due to thermal deformation of the housing or the like, the directions of the exit beam directions are aligned. Therefore, by applying this optical scanning device to an image forming apparatus, the relative positional relationship between the beams is maintained, and a high-quality color image without color shift or color change can be formed.
[0060]
According to a second aspect of the present invention, there is provided a deflecting unit that deflects each light beam emitted from a plurality of light source units and is separated in the sub-scanning direction collectively to perform main scanning, and divides each scanned light beam into these light beams. In an optical scanning device having a plurality of image forming means for forming an image on a surface to be scanned corresponding to the above, and a housing means for holding these means, the plurality of light source means have a common direction in which their emission axes are aligned. , And are detachably held by housing means so that the respective emission positions are at least a predetermined interval in the sub-scanning direction. Therefore, the mounting posture between the light sources can be accurately adjusted, there is no deviation due to the assembling or replacement of the light source means, and the relative posture of each light source is always maintained even if there is an environmental change. Therefore, by applying this to an image forming apparatus, a high-quality color image without color shift or color change can be formed.
[0061]
According to a third aspect of the present invention, in the optical scanning device according to the second aspect, the beam converging means for emitting the light beams from the plurality of light source means integrally held in the main scanning direction in proximity to each other is shared. It is characterized by being provided in. This makes it possible to accurately match the emission directions between the beams, and there is no deviation due to assembly or replacement of the light source means.
[0062]
According to a fourth aspect of the present invention, there is provided a deflecting unit that deflects light beams emitted from a plurality of light source units and separated in the sub-scanning direction collectively to perform main scanning, and converts the scanned light beams into these light beams. In an optical scanning device having a plurality of image forming means for forming an image on a surface to be scanned corresponding to the above, and a housing means for holding these means, each light source is arranged on an optical path from the plurality of light source means to the deflecting means. Beam converging means for causing a light beam from the means to sequentially approach the deflecting means from one side in the main scanning direction and a beam for sequentially branching each light beam scanned by the deflecting means in accordance with the arrangement order in the sub-scanning direction The branching means is provided on the housing means. Therefore, the distance between the beams at the position of the deflecting means, such as a polygon mirror, can be narrowed, and the beams can be reliably separated after being deflected.The thickness of the deflecting means is minimized, heat generation is suppressed, and environmental temperature changes occur. Can be difficult.
[0063]
According to a fifth aspect of the present invention, in the optical scanning device according to the first, second or fourth aspect, the plurality of light source units each have a contact surface in a direction orthogonal to the emission axis, and the contact surfaces are common. It is characterized by being held against the support member. Therefore, the emission directions between the beams can be accurately adjusted, and by aligning the regulating means, the relative attitude of each light source is always maintained even if there is an environmental change.
[0064]
According to a sixth aspect of the present invention, in the optical scanning device of the fifth aspect, each of the contact surfaces is held so as to be substantially flush with each other. This makes it possible to more accurately match the emission directions between the beams, and to prevent displacement due to assembly or replacement of the light source means.
[0065]
According to a seventh aspect of the present invention, in the optical scanning device according to the first, second or fourth aspect, at least one of the light source means is disposed so that the light emitting source is eccentric from the emission axis in a plane orthogonal to the emission axis. In addition, the emission direction is set so that the light beam from each light source crosses the emission axis. Therefore, when assembling the light source means, the position of the beam spot can be adjusted by a simple operation of inclining in a plane perpendicular to the emission axis, and the writing start timing such as a multi-beam scanning device that simultaneously scans a plurality of beams. A scanning line pitch that cannot be adjusted by adjustment can be accurately adjusted. When this optical scanning device is applied to an image forming apparatus, a high-quality image without density unevenness can be formed.
[0066]
According to an eighth aspect of the present invention, in the optical scanning device according to the seventh aspect, the light source means includes a plurality of light emitting sources arranged in a plane perpendicular to the emission axis, and the light beams from the respective light emitting sources are mutually connected. The injection direction is set so as to intersect. As a result, each beam spot can be separated on the surface to be scanned and can be simultaneously recorded by a plurality of scanning lines, so that high-speed and high-density image recording can be performed without complicating the structure. An adaptive optical scanning device can be provided.
[0067]
According to a ninth aspect of the present invention, in the optical scanning device of the eighth aspect, the light source is held so as to be capable of adjusting a tilt in a plane perpendicular to the emission axis. When assembling the light source means, it is possible to accurately adjust the scanning line pitch between each color by simple work of tilting in the plane perpendicular to the emission axis, enabling high-quality color image recording without color shift or color change A simple optical scanning device can be provided.
[0068]
According to a tenth aspect of the present invention, in the optical scanning device according to the first, second or fourth aspect, the pre-deflection imaging means for converging the light beams from the plurality of light sources in the sub-scanning direction on the deflecting surface by the deflecting means is a beam. It is provided in the optical path to the merging means, and is arranged so that the distance from the light source means to the pre-deflection imaging means differs according to the arrangement order in the sub-scanning direction. With such a configuration, the pre-deflection imaging means of each light source can be shifted in the main scanning direction and the light source position can be aligned and arranged on a plane perpendicular to the emission axis. The beam interval in the sub-scanning direction can be narrowed without depending on the diameter, the heat generation can be suppressed by minimizing the thickness of the deflecting means, the environmental temperature does not easily change, and the influence of the heat generation can be made uniform among the light sources. Therefore, by applying this to an image forming apparatus, a high-quality color image without color shift or color change can be formed.
[0069]
According to an eleventh aspect of the present invention, in the optical scanning device according to the first, second or fourth aspect, the pre-deflection imaging means for converging the light beams from the plurality of light source means in the sub-scanning direction on the deflecting surface of the deflecting means comprises a light source. The imaging means before deflection is provided in the optical path from the means to the beam merging means, and has different convergence forces corresponding to the arrangement order in the sub-scanning direction. By making the convergence of the pre-deflection imaging means different according to the difference in the optical path lengths from the beam converging means to the deflecting means, the pre-deflection imaging from each light source is possible even if the distance between the light sources in the main scanning direction increases Since the optical path length to the means can be minimized and the light source position can be aligned on a plane perpendicular to the emission axis, the housing is reduced in size and is less susceptible to thermal deformation. Can be reduced.
[0070]
According to a twelfth aspect of the present invention, in the optical scanning device according to the first, second or fourth aspect, the pre-deflection imaging means for converging the light beams from the plurality of light source means in the sub-scanning direction on the deflecting surface of the deflecting means is provided. It is provided in each of the optical paths from the joining means to the deflecting means, and the pre-deflection imaging means are arranged in layers in the sub-scanning direction and are integrally formed. Even if the housing is affected by thermal deformation and changes in the attitude of the pre-deflection imaging means, there will be no relative misalignment, so the difference between the light sources can be reduced and high quality without color shift or color change. A color image can be recorded.
[0071]
According to a thirteenth aspect of the present invention, in the optical scanning device according to the tenth, eleventh, or twelfth aspect, the plurality of light source units are arranged so that the respective light emitting sources are substantially aligned on the same plane. It is easy to integrate the components into a single support member, and each light source can be directly mounted on a common drive circuit board, so that the number of parts can be reduced and the number of work steps such as wiring connection is reduced. Thus, the production efficiency is improved, and a low-cost optical scanning device can be provided.
[0072]
The invention according to claim 14 includes an optical writing device for forming a latent image on the surface of a photoreceptor, a developing device for developing the latent image as a toner image, and a transfer unit for transferring the toner image to transfer paper. In the above image forming apparatus, the optical writing device comprises the optical scanning device according to any one of claims 1 to 13. Therefore, the effect obtained by the optical scanning device according to any one of the first to thirteenth aspects can be obtained, and a high-quality color image without color shift or color change can be formed.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an embodiment of an optical scanning device according to the present invention.
FIG. 2 is a partial cross-sectional front view of the embodiment.
FIG. 3 is a side sectional view showing an example of a light source unit applicable to the present invention.
FIG. 4 is an exploded perspective view showing a main part of the light source unit.
FIG. 5 is an exploded perspective view showing an example of a support portion of a reflection mirror in a beam merging unit applicable to the present invention.
FIG. 6 is a perspective view showing another example of a light source unit and a beam merging unit applicable to the present invention.
FIG. 7 is an exploded perspective view showing another example of a light source unit applicable to the present invention.
FIG. 8 is a side sectional view showing still another example of the light source unit applicable to the present invention.
FIG. 9 is a conceptual diagram showing a state of adjusting a beam spot interval by the light source unit.
FIG. 10 is an exploded perspective view showing still another example of the light source unit and the beam merging unit applicable to the present invention.
FIG. 11 is a sectional side view of the same.
FIG. 12 is an exploded perspective view showing an example of a scan line tilt and bend correction mechanism applicable to the present invention.
FIG. 13 is a front view schematically showing an embodiment of the image forming apparatus according to the present invention.
FIGS. 14A and 14B are diagrams showing how a tilt of a focal line is adjusted by turning a toroidal lens used in a scanning imaging optical system. FIG. Indicates adjustment of the inclination of the generatrix in the main scanning direction.
15 (a) is a plan view and FIG. 15 (b) is a front view showing an example in which a reflecting mirror in a beam merging means applicable to the present invention is integrally formed.
[Explanation of symbols]
110 housing means
201 Semiconductor laser as light source means
202 Semiconductor laser as light source means
203 Semiconductor laser as light source means
204 Semiconductor laser as light source means
205 coupling lens
206 coupling lens
207 coupling lens
208 coupling lens
209 cylinder lens
210 cylinder lens
211 cylinder lens
212 cylinder lens
213 Deflection means
214 Reflecting mirror as beam merging means
215 Reflecting mirror as beam merging means
216 Reflecting mirror as beam merging means
217 Reflecting mirror as beam merging means
218 fθ lens as imaging means
224 Beam splitting means
225 Beam splitting means
226 Beam splitting means

Claims (14)

A deflecting unit that deflects the light beams emitted from the plurality of light source units and is separated in the sub-scanning direction collectively to perform main scanning; and connects the scanned light beams to a surface to be scanned corresponding to these light beams. In an optical scanning device having a plurality of imaging means for imaging and a housing means for holding these means,
The plurality of light source units are arranged so that the directions of the respective emission axes are aligned and at least intervals of the respective emission positions in the main scanning direction are predetermined intervals, and the light beams from each light source unit toward the deflecting unit are provided. Beam converging means is provided on the optical path of
The optical scanning device, wherein the beam converging means is held by the housing means and sequentially makes the positions of the light beams in the main scanning direction closer to each other and makes the light beams incident on the deflecting means. A deflecting unit that deflects the light beams emitted from the plurality of light source units and is separated in the sub-scanning direction collectively to perform main scanning; and connects the scanned light beams to a surface to be scanned corresponding to these light beams. In an optical scanning device having a plurality of imaging means for imaging and a housing means for holding these means,
The plurality of light source means are arranged such that the directions of the respective emission axes are aligned and integrally held by a common support member, and the housing means is arranged such that the respective emission positions are at least predetermined intervals in the sub-scanning direction. An optical scanning device, which is detachably held in a device. 3. The light according to claim 2, wherein said common support member is provided with a beam merging means for emitting light beams from said plurality of integrally held light source means in the main scanning direction. Scanning device. A deflecting unit that deflects the light beams emitted from the plurality of light source units and is separated in the sub-scanning direction collectively to perform main scanning; and connects the scanned light beams to a surface to be scanned corresponding to these light beams. In an optical scanning device having a plurality of imaging means for imaging and a housing means for holding these means,
The beam converging means is arranged on an optical path from the plurality of light source means to the deflecting means, and the light beams from the respective light source means are sequentially approached from one side in the main scanning direction and are incident on the deflecting means. A beam splitting means for splitting each of the light beams sequentially according to the arrangement order in the sub-scanning direction. 3. The light source device according to claim 1, wherein each of the plurality of light sources has a contact surface in a direction perpendicular to the emission axis, and each of the contact surfaces is held against a common support member. Or the optical scanning device according to 4. 6. The optical scanning device according to claim 5, wherein said contact surfaces are held so as to be substantially flush with each other. At least one of the light source means is arranged so that the light source is eccentric from the emission axis in a plane perpendicular to the emission axis, and the emission direction is set so that the light beam from each light source intersects the emission axis. 5. The optical scanning device according to claim 1, wherein the optical scanning device is used. The light source means is characterized in that a plurality of light emitting sources are arranged in a plane perpendicular to the emission axis, and the emission direction is set so that light beams from the respective light emitting sources intersect each other. The optical scanning device according to claim 7. 9. An optical scanning device according to claim 8, wherein said light source means is held so as to adjust an inclination in a plane perpendicular to said emission axis. Pre-deflection imaging means for converging the light beams from the plurality of light sources in the sub-scanning direction on the deflection surface of the deflection means are provided in the optical path leading to the beam merging means, respectively. 5. The optical scanning device according to claim 1, wherein the distance to the means is different so as to correspond to the arrangement order in the sub-scanning direction. Pre-deflection imaging means for converging light beams from the plurality of light source means in the sub-scanning direction on the deflection surface of the deflection means are provided in an optical path from the light source means to the beam merging means, respectively, and the pre-deflection imaging means is provided. 5. The optical scanning device according to claim 1, wherein the optical scanning device has different convergence forces corresponding to the arrangement order in the sub-scanning direction. Pre-deflection imaging means for converging the light beams from the plurality of light sources in the sub-scanning direction on the deflecting surface of the deflecting means are respectively provided in the optical path from the beam converging means to the deflecting means. 5. The optical scanning device according to claim 1, wherein the optical scanning device is arranged integrally in a layered manner in the scanning direction. 13. The optical scanning device according to claim 10, wherein the plurality of light source units are arranged such that the respective light emitting sources are arranged substantially on the same plane. An image forming apparatus comprising: an optical writing device that forms a latent image on the surface of a photoreceptor; a developing device that develops the latent image as a toner image; and a transfer unit that transfers the toner image to transfer paper. 14. An image forming apparatus comprising the optical scanning device according to any one of claims 1 to 13.

Images