JP2004246032A - Optical write-in device and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To support a lens and to adjust the position of the lens in the optical axis direction with a simple structure in an optical write-in device. <P>SOLUTION: In the optical write-in device which has a light source, a first optical system, and an optical scanning system including a scanning means and a second optical system and forms a latent image by irradiating an image carrier with a light beam emitted from the light source via the optical scanning system, the first optical system is composed of a cylinder lens and a lens holding member 20 which supports the lens, the lens holding member 20 is fitted movably along an optical axis direction on a case of the device, and when fitted on the case, a lens holding part 20a which supports the cylinder lens, namely the upper side, is positioned by a main body in a direction opposite to the fitting direction of the cylinder lens on the lens holding part 20a. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an optical writing device that performs optical writing using a laser beam, and an image forming apparatus using the optical writing device, such as a digital copier, a printer, and a facsimile, and more particularly, to a light having an optical system adjustment function. The present invention relates to a writing device and an image forming device.
[0002]
[Prior art]
In recent image forming apparatuses, high-quality images have been demanded, and high-performance optical systems have been used for optical writing apparatuses. It is sufficient that the high performance can be maintained only with the parts, but there are cases where there are dimensional errors and assembling errors of the parts, so that an adjustment work may be required at the time of assembling the parts. After the optical writing device is assembled, the position of a part of the optical system may be adjusted so as to obtain a desired beam diameter on the photoconductor. Of course, the adjustment operation is not performed repeatedly, and even if the adjustment is performed in the middle of the assembling process, it is often necessary to confirm again in the final process. Therefore, it is more efficient that the adjustment work is performed after all the assembling operations. Since the optical writing device is often in a sealed state or a state close to it due to its characteristics, it is not easy to make contact with parts inside the device after all the assembly is completed.
[0003]
Therefore, for example, Japanese Patent Application Laid-Open No. 5-34618 proposes a device having a configuration in which a lens is brought into frictional contact with a lens holding member and moved in the optical axis direction by a frictional force. Japanese Patent Application Laid-Open No. 8-304726 proposes a configuration in which a lens is moved in an optical axis direction. Further, Japanese Patent Application Laid-Open No. Hei 10-215351 proposes an apparatus for vertically moving a cylindrical lens for each color so that color shift does not occur.
[0004]
[Patent Document 1]
JP-A-5-34618
[Patent Document 2]
JP-A-8-304726
[Patent Document 3]
JP-A-10-215351
[Problems to be solved by the invention]
However, the invention described in Patent Document 1 does not disclose a method of holding a lens and a method of fixing a lens holding member in a vertical direction, and uses a roller member for guiding in a direction parallel to an optical axis. It cannot be denied that the number of components increases.
[0008]
Further, in the invention described in Patent Document 2, there is only proposed a configuration in which the lens is moved in the optical axis direction, and there is no specific disclosure of the moving mechanism. It only describes that it is moving like.
[0009]
Further, the invention described in Patent Literature 3 has a structure in which an electric driving device has to be employed because the cylindrical lens is moved up and down every time the color changes.
[0010]
SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances of the related art, and has as its object to use an optical writing device capable of holding a lens and adjusting a position in an optical axis direction with a simple structure, and using the optical writing device. To provide an improved image forming apparatus.
[0011]
Another object of the present invention is to provide an optical writing device in which a housing has a function of positioning a lens in a vertical direction and position adjustment in an optical axis direction in a state where the optical writing device is assembled. An object of the present invention is to provide an image forming apparatus used.
[0012]
[Means for Solving the Problems]
To achieve the above object, the first means has an optical scanning system including a light source, a first optical system, a scanning means, and a second optical system, and light emitted from the light source via the optical scanning system. In an optical writing device that forms a latent image by irradiating a beam on an image carrier, the first optical system includes a lens and a holding member that holds the lens, and the holding member is attached to a housing of the device. The lens holder is movably attached along the optical axis direction, and when attached to the housing, the holding unit for holding the lens is moved by the apparatus body in a direction opposite to the mounting direction when the lens is mounted on the holding unit. It is characterized by being positioned.
[0013]
According to a second aspect, in the first aspect, the attachment of the holding member to the housing is performed by snap-fitting a groove formed long in the optical axis direction.
[0014]
A third means is the first means, wherein an eccentric cam is provided between the housing and the holding member, and the holding member is moved by rotation of the eccentric cam.
[0015]
The fourth means is characterized in that, in the third means, a regulating member which slides on the outer periphery of the eccentric cam and regulates the rotation of the eccentric cam is provided.
[0016]
A fifth means is the fourth means, wherein the eccentric cam is provided with a portion which is elastically deformed by the contact of the regulating member.
[0017]
A sixth means is the first means, wherein the lens is a cylinder lens.
[0018]
A seventh means is an optical writing device according to the first to sixth means, an image carrier for forming an electrostatic latent image by the optical writing device, and a latent image formed on the image carrier for visualizing the latent image. And an image forming means for forming a visible image on a recording medium.
[0019]
According to the first means, while the lens is held by the holding member, the movement can be adjusted in the optical axis direction while the case is provided with a highly accurate vertical positioning in the housing. Dimensional tolerance of other parts does not enter, and high-precision positioning and a desired beam diameter can be obtained.
[0020]
According to the second means, mounting and position adjustment can be performed with a simple structure using a snap fit. At this time, since the position can be adjusted by moving the holding member from the outside of the housing along the longitudinal direction of the groove, the beam diameter can be adjusted without removing a component such as a cover after assembling the optical writing device. Can be performed, and more accurate adjustment can be performed.
[0021]
According to the third means, the position adjustment including the fine adjustment can be easily performed by rotating the eccentric cam. Also in this case, since the holding member can be moved along the longitudinal direction of the groove by rotating the eccentric cam from the outside of the housing, the components such as the cover are removed after the optical writing device is assembled. The beam diameter can be adjusted without any adjustment, and more accurate adjustment can be performed.
[0022]
According to the fourth means, since the regulating member is provided, the position at the time of adjustment can be reliably held.
[0023]
According to the fifth means, since the regulating member is provided with a portion which is elastically deformed by the contact of the regulating member, it can be securely held by utilizing not only the frictional force but also the elastic force, and the position is maintained after the adjustment. Reliability can be improved.
[0024]
According to the sixth means, since positioning in the vertical direction with strict accuracy is performed by the housing, the position in the direction orthogonal to the longitudinal direction of the cylinder lens can be held with high accuracy.
[0025]
According to the seventh means, the effects of the first to sixth means can be exerted also in the image forming apparatus.
[0026]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0027]
FIG. 1 is a configuration diagram schematically showing a color laser printer as an image forming apparatus according to the present embodiment, FIG. 2 is a plan view of an optical writing (exposure) device, and FIG. FIG.
[0028]
In FIG. 1, a color laser printer 1 as an image forming apparatus employs an electrophotographic image forming process, and basically includes an image forming apparatus 2, a sheet feeding device 3 including a sheet feeding cassette, and a fixing device 4. Have been. The image forming apparatus 2 includes photosensitive drums 10Y, 10C, 10M, and 10K, an exposure unit 6, a transfer unit (transfer roller 12), and the like, and includes a plurality of photosensitive drums (hereinafter, generally denoted by reference numeral 10). The charging unit 8, the exposure unit 6, the developing unit 9, the transfer unit, and the cleaning unit 7 are arranged for each color in the order of rotation. Hereinafter, the description will be generally given with only the reference numerals, and when it is necessary to touch the elements for each color, the description will be given with Y, C, M, and K added to the reference numerals.
[0029]
The charging unit 8 includes a conductive roller formed in a roller shape, and supplies a charging bias voltage to the roller from a power supply device to uniformly charge the photosensitive layer on the surface of the photosensitive drum 10. The exposure unit 6 irradiates the surface of the photosensitive drum 10 with laser light that is turned on / off based on image data, and forms an electrostatic latent image on the photosensitive drum 10. The developing unit 9 includes a developing roller and a developer accommodating section, and visualizes an electrostatic latent image on the photosensitive drum 10. A color image forming apparatus often has four developing means of three colors of yellow Y, cyan C, and magenta M and black K for forming a color image like a color laser printer. In the present embodiment, as shown in FIG. 1, four image forming units of yellow Y, cyan C, magenta M, and black K are arranged from the left of the figure (from the upstream side in the rotation direction of an intermediate transfer belt described later). ing. However, since a full-color image can be formed even with three colors of yellow Y, cyan C, and magenta M excluding black, the image forming apparatus can be configured without black K.
[0030]
The transfer unit transfers the image visualized by the toner on the photosensitive drum 10 from the photosensitive drum 10 to an intermediate transfer belt 11 as an intermediate transfer body by a transfer roller 12. The intermediate transfer belt 11 is stretched between a driving roller, a driven roller, and a pressure roller, and rotates counterclockwise in the drawing as the driving roller rotates. The toner image formed on each photoconductor drum 10 comes into contact with the intermediate transfer belt 11 and a predetermined bias voltage is applied to a transfer roller 12 (12Y, 12C, 12M, 12K) disposed on the back surface of the intermediate transfer belt 11. Is transferred onto the intermediate transfer belt 11. Such transfer is generally called primary transfer, and such a transfer unit is also called primary transfer unit. The cleaning unit 7 removes the developer remaining on the photosensitive drum 10 after the transfer to the intermediate transfer belt 11 before the next image forming operation.
[0031]
The transfer method of such a color image forming apparatus is roughly classified into the following two methods. One is a method in which images formed by a plurality of photosensitive drums 10Y, 10C, 10M, and 10K are superimposed on the intermediate transfer belt 11 and then transferred to a transfer material (this is referred to as secondary transfer). So-called intermediate transfer type. The other is a so-called direct transfer system in which images formed on the photosensitive drums 10Y, 10C, 10M, and 10K are directly transferred to a transfer material and are superimposed on the transfer material. The color laser printer 1 shown in FIG. 1 is of the former type.
[0032]
In the intermediate transfer method described in the present embodiment, images superimposed on the intermediate transfer belt 11 are collectively transferred onto a transfer material by a transfer roller 13 as a transfer unit (referred to as a secondary transfer unit). The transfer material is often a recording material such as paper (hereinafter, also referred to as transfer paper), and is stored in the paper feed cassette 3a of the paper feed device 3 described above. The transfer paper is separated and conveyed one by one by the pickup roller 3b. The transfer paper separated and conveyed one by one by the pickup roller 3b is conveyed to the transfer roller 13 as the secondary transfer means by the paper feed roller 3c, where the full-color toner superimposed on the intermediate transfer belt 11 there. The image is transferred to transfer paper. After that, in order to fix the image, the transfer paper is conveyed to the fixing device 4 and heated and pressed by the fixing device 4 to fix the image. Further, the sheet is discharged from the sheet discharging roller 3e to the outside of the apparatus via the conveying roller 3d.
[0033]
FIG. 2 shows the internal structure of the exposure unit 6 in detail. As can be seen from FIG. 2, the basic configuration of the exposure unit 6 includes a laser light source (unit) 61 that oscillates a laser beam L and a deflection scanning unit that deflects and scans the laser beam L modulated based on an image signal. A mirror mirror 62, an imaging optical system (second optical system) 63 for imaging the laser beam L deflected and scanned to a desired size on the photosensitive drum 10, and a scanning start timing of the laser beam L. It comprises a synchronization detecting section 64 as a synchronization detecting means. The polygon mirror 62 is driven to rotate at high speed by a polygon motor 62a. In the present embodiment, four laser light sources 61Y, 61M, 61C and 61K are mounted to irradiate the laser beam L to the four photoconductors 10 of Y, C, M and K, and two light sources 61Y and 61C are provided. And a so-called opposing scanning method in which the light is incident on both sides of the polygon mirror 62 separately into 61M and 61K.
[0034]
In the present embodiment, a semiconductor laser (LD) is used as a light emitting source, and this semiconductor laser, a collimating lens that makes the divergent light emitted from the semiconductor laser substantially parallel, a semiconductor laser drive circuit board, and these are held. A laser light source unit (LD unit) 61 is composed of the holding member (base).
[0035]
The laser beam L emitted from the LD unit 61 passes through the aperture 65 and the cylinder lens 66 and reaches the polygon mirror 62 as can be seen from FIG. In order to make the two laser beams LY, LC and LM, LK independently incident on the polygon mirror 62 from one side, mirrors 67a, 67b are arranged on one optical path as shown in FIG. In this embodiment, the cylinder lens 66 constitutes a first optical system.
[0036]
When the rotation speed of the polygon mirror 62 is high enough to exceed 30,000 rpm, soundproof glass is often used in front of the polygon mirror 62 for noise control or the like. In the figure, a soundproof glass 68 is provided on both sides of the polygon mirror 62.
[0037]
The laser beam deflected and scanned by the polygon mirror 62 again passes through the soundproof glass 68 and enters the imaging lens 63. Thereafter, the laser beam guided to the photosensitive drum 10 reaches the photosensitive drum 10 via the mirror 69. The irradiation angle with respect to the surface of the photosensitive drum 10 is set to be substantially the same for each of the Y, C, M, and K colors. On the other hand, for synchronization detection for determining the timing of starting writing, the laser beam L passing through the imaging lens 63 is turned back by the synchronization detection mirror 64a to reach the synchronization detection unit 64. The synchronization detector 64 includes an imaging lens 64b, an electric circuit board 64c having a photoelectric element, and a holding member 64d for holding them.
[0038]
Since the original meaning of the synchronization detection is to take the timing of the scanning light, it is sufficient that the synchronization detection is provided prior to the normal scanning. However, in this embodiment, a change in the speed (or time) of one scanning is detected. For this purpose, a detecting means is also provided at the end of scanning. FIG. 2 shows a configuration for synchronizing before and after this scanning. In this example, one synchronization detection unit 64 detects the upper and lower scanning beams.
[0039]
FIG. 3 shows an example of a configuration in which a laser beam is emitted from one optical deflector to all of the plurality of photosensitive drums 10Y, 10C, 10M, and 10K. Although not shown in the figure, individual exposure means can be provided for each of the plurality of photoconductors. For example, it is also possible to adopt a configuration in which four exposure means are respectively arranged on four photoconductors to perform optical writing. In FIG. 3, dustproof glass 60Y, 60C, 60M, 60K is provided at the exit from the exposure unit 6 to the photosensitive drum 10 in order to prevent dust from entering the exposure means. It is not always necessary as an element. In the figure, the dustproof glass is in a state of being attached to a cover 71 of the optical writing device.
[0040]
The above components are housed in the housing 70 and closed by the cover 71.
[0041]
Hereinafter, the configuration of the present invention will be described in more detail. FIGS. 2 and 3 show an optical writing device having a configuration in which four beams are emitted in order to write a latent image on four photosensitive members. However, the present embodiment is equivalent to four optical paths. A description will be given on behalf of the black writing system.
[0042]
FIG. 4 shows a specific example of the lens holding member 20. In this embodiment, the lens holding member 20 is for holding a cylinder lens 66 constituting the first optical system. The cylinder lens 66 is inserted into the lens holding portion 20a of the lens holding member 20 from the bottom side in FIG. , Will be retained. The lens holding member 20 is integrally molded of an elastic resin material, and has protrusions 21a and 21b for pressing and holding the inserted cylinder lens 66, and a tip of the cylinder lens 66 on the insertion side opposite to the insertion side of the cylinder lens 66. A projection 22 for holding the (upper) portion is provided. Accordingly, the cylinder lens 66 can be held without dropping in a state of being inserted into the lens holding member 20. The projection 22 is pressed from the main body side when the lens holding member 20 is attached to the main body, and applies a predetermined pressure to the cylinder lens 66 from the upper side in FIG. Thereby, it is stably and elastically held in relation to the projections 21a and 21b.
[0043]
The lens holding member 20 is provided with four projections 23 to be attached to the housing 6a of the exposure unit 6, and constitutes an attachment leg. The projection 23 is inserted into a long groove-shaped mounting hole 6b formed in the housing 6a as shown in FIG. 5, and elastically engages with the inner edge of the mounting hole 6b to fix the lens holding member 20. The shape and position of the protrusion 23 and the size and position of the mounting hole 6b are set so that the protrusion 23 can be so-called snap-fit to the mounting hole 6b. In this embodiment, four protrusions 23 are provided, but the number is appropriately set according to the shape and size. As shown in FIGS. 5 and 6, the mounting hole 6b is formed to be long in the optical axis direction for moving in the optical axis direction (for adjusting the position in the optical axis direction). An inclined surface 20c is provided on the bottom plate portion 20b, and a similar inclined surface 25, a cylindrical convex portion 26, and the like are provided on an attached portion of the housing 6a. Thereby, it is possible to move only in the optical axis direction while the slope 20c slides with respect to the slope 25 or the protrusion 26.
[0044]
The movement adjustment of the cylinder lens 66 in the optical axis direction is performed by moving the lens holding member 20 from the outside of the housing 6a in the optical axis direction. At this time, as shown in FIG. When a convex portion 27 protruding outward is provided on the lens holding member 20 and is protruded to the outside of the housing 6a from a protruding hole 6d provided in the housing 6a, and the protruding convex portion 27 is operated, the lens holding Adjustment can be easily performed with the member 20 attached.
[0045]
Also. The shape of the holding member in FIG. 4 is an example in which the lens holding portion 20a is shifted to one side of the lens holding member 20. The position of the lens holding portion 20a is appropriately determined according to the internal structure of the optical writing device. However, the lens holding portion 20a can be disposed at the center as shown in FIG. 8, and the arrangement shown in FIG. Needless to say, it is better.
[0046]
As described above, the lens holding member 20 is provided with four protrusions (legs) 23 that engage with the mounting portion of the housing, and when the lens holding member 20 is inserted into the mounting hole 6b of the housing 6a, the resin is removed. The protrusion 23 elastically engages with the inner edge of the mounting hole 6b due to the elasticity described above, and is fixed by a so-called snap fit. At this time, since the mounting hole 6b is formed to be long in the optical axis direction as described above, it is possible to move in the longitudinal direction while the projection 23 is snap-fitted to the mounting hole 6b. For this movement, it is possible to provide a convex portion 27 as shown in FIG. 7 and to operate from this convex portion 27. However, when the lens holding member 20 is attached to the housing 6a as shown in FIG. The eccentric cam 30 may be provided between the camera and the lens holding member 20 to be moved by the rotation of the eccentric cam 30.
[0047]
That is, support holes 6c and 20c for supporting the rotating shaft 30a of the eccentric cam 30 are provided in the housing 6a and the lens holding member 20, respectively, and the rotating shaft 30a is inserted into each of the supporting holes 6c and 20c to mount the lens holding member 20. It is mounted on the housing 6. A projection 32 is provided on the housing 6 side for sliding contact with the eccentric cam 30. When the lens holding member 20 is mounted on the housing 6, the cam outer peripheral portion 30 b of the eccentric cam 30 contacts the projection 32. Thus, when the eccentric cam 30 is rotated, the position of the rotation shaft 30a changes, and the position of the lens holding member 20 changes in the optical axis direction according to this change. In this way, the rotation can be converted into the movement in the optical axis direction by the eccentric cam 30, and at the same time, the amount of movement can be appropriately set by the amount of eccentricity of the cam, so that fine adjustment is possible and the adjustment work can be made easier. . Also, an arc-shaped groove 31 that penetrates or does not penetrate the disk portion of the eccentric cam 30 is provided in a part of the eccentric cam 30 so that an outer peripheral portion 30b abutting on the protrusion 32 is partially elastically deformed. And attached. As a result, the eccentric cam 30 does not rotate due to the influence of external vibrations other than giving an arbitrary rotational force at the time of adjustment, and a highly reliable position holding function can be exhibited for a long time.
[0048]
Further, as shown in FIG. 10, if an elastic member 33 is provided between the lens holding member 20 and the housing 6 so that a holding force using an elastic force can be added, only a high holding function can be obtained. In addition, when the holding function lens holding member 20 is attached to the housing 6, it is possible to improve the ease of attachment and the mobility in the optical axis direction by preventing elastic force from being applied.
[0049]
【The invention's effect】
As described above, according to the present invention, it is possible to hold the lens and adjust the position in the optical axis direction with a simple structure. In addition, the housing is provided with a function of positioning the lens in the vertical direction, and the position adjustment in the optical axis direction can be easily performed in a state where the optical writing device is assembled, so that a high-precision optical system can be manufactured at low cost. Can be configured.
[Brief description of the drawings]
FIG. 1 is a configuration diagram schematically illustrating a color laser printer as an image forming apparatus according to an embodiment.
FIG. 2 is a plan view of the optical writing device according to the embodiment.
FIG. 3 is a sectional view schematically showing an optical writing device according to the embodiment.
FIG. 4 is a perspective view of a lens holding member according to the embodiment.
FIG. 5 is an explanatory view showing a state where the lens holding member of FIG. 4 is attached to a housing.
FIG. 6 is an explanatory diagram of a housing portion similar to FIG. 5;
FIG. 7 is a diagram illustrating an example of a protrusion provided for moving a lens holding member.
FIG. 8 is a diagram illustrating an example in which a lens holding portion of a lens holding member is provided at a central portion.
FIG. 9 is a perspective view of a main part showing an eccentric cam inserted between a lens holding member and a housing.
FIG. 10 is a view showing an example in which an elastic member is provided on a lens holding member.
[Explanation of symbols]
6. Optical writing device (exposure means)
6a Housing 6b Mounting hole 6d Projection hole 7 Cleaning means 8 Charging means 9 Developing means 10Y, 10C, 10M, 10Bk Photoconductor 12 Transfer roller 20 Lens holding member 20a Lens holding portion 20b Bottom plate portion 20c Slopes 21a, 21b, 22, 23 Projection 25 Slope 26 Convex part 30 Eccentric cam 30a Rotary shaft 31 Groove 32 Projection

Claims (7)

A light source, a first optical system, an optical scanning system including a scanning unit and a second optical system, and irradiating a light beam emitted from the light source onto the image carrier through the optical scanning system to form a latent image. In the optical writing device to be formed,
The first optical system includes a lens and a holding member that holds the lens,
The holding member is attached movably along the optical axis direction with respect to the housing of the device, and when attached to the housing, a holding unit that holds a lens mounts the lens on the holding unit. The optical writing device is positioned by the device main body in a direction opposite to the mounting direction of the optical writing device. 2. The optical writing device according to claim 1, wherein the attachment of the holding member to the housing is performed by snap-fitting a groove formed long in the optical axis direction. The optical writing device according to claim 1, wherein an eccentric cam is provided between the housing and the holding member, and the holding member is moved by rotation of the eccentric cam. 4. The optical writing device according to claim 3, further comprising a regulating member that slides on an outer periphery of the eccentric cam and regulates rotation of the eccentric cam. 5. The optical writing device according to claim 4, wherein the eccentric cam is provided with a portion that is elastically deformed by the contact of the regulating member. The optical writing device according to claim 1, wherein the lens is a cylinder lens. An optical writing device according to any one of claims 1 to 6,
An image carrier that forms an electrostatic latent image by the optical writing device;
Image forming means for visualizing the latent image formed on the image carrier and forming a visible image on a recording medium,
An image forming apparatus comprising:

Images