JP6418481B2 - Optical scanning apparatus and image forming apparatus - Google Patents

Description

The present invention relates to an optical scanning device and an image forming apparatus.

  In an image forming apparatus such as a copying machine, a printer, or a facsimile machine, a latent image is formed on a latent image carrier by scanning writing light corresponding to image information on the latent image carrier, and the latent image is developed. It is known to obtain images. An optical scanning device as means for scanning writing light includes a polygon mirror that deflects and scans writing light from a light source, and a latent image carrier that is an object to be irradiated with the writing light that is deflected and scanned by the polygon mirror. In general, an optical element such as a long lens for image formation on the surface is provided.

  In such an optical scanning device, the curvature of field of the optical element, the torsion of the housing of the optical scanning device, the thermal deformation of each component of the optical scanning device due to the heat generated from the polygon motor that rotationally drives the polygon mirror, and the latent image Due to various factors such as twisting when the carrier is attached, the scanning lines on the surface of the latent image carrier due to the writing light are bent or inclined. If the scanning line is bent or inclined, a correct latent image corresponding to the image information cannot be formed on the surface of the latent image carrier, and a normal image cannot be formed.

  In particular, in a so-called tandem type color image forming apparatus in which images of different colors (visible images) are formed on a plurality of latent image carriers and these images are superimposed on each other to form a color image, each latent image is formed. If the curve or inclination of the scanning line is relatively deviated between the image carriers, this appears as color misregistration. In order to prevent the occurrence of this color misregistration, scanning line adjustment means for adjusting the bending and inclination of the scanning line is necessary.

  Patent Document 1 describes a scanning line adjustment device as a scanning line adjustment unit that adjusts the bending and inclination of a scanning line, and an optical scanning device and an image forming apparatus mounted thereon. The bending of the scanning line is performed by a scanning line bending adjustment unit that is attached to the center of the bracket that supports both ends of the long lens and adjusts the amount of bending at the center of the long lens by pressing the long lens. . In addition, the inclination of the scanning line is adjusted to adjust the inclination of the long lens rotating around the center fulcrum by contacting with one end of the bracket supporting the long lens and displacing in the contact direction. This is done by the adjustment unit.

FIG. 17A is a diagram for explaining the outline of the scanning line adjustment apparatus described in Patent Document 1. FIG.
This scanning line adjustment device includes a long lens unit (tilt varying member) 250 composed of a long lens 251 and a bracket 252 that holds the long lens 251, a drive motor 256, a drive motor holder 257, and rotation axes of the drive motor 256. An adjuster 258 that is screwed into the screw portion is provided.
The adjuster 258 has a D-shaped cross section and is inserted into the D-shaped adjuster insertion port of the drive motor holder 257. The top of the adjuster 258 protrudes from the adjuster insertion port and comes into contact with the bracket 252. When the rotation shaft of the drive motor 256 rotates and the adjuster 258 moves up and down relative to the rotation shaft of the drive motor, the motor side end of the long lens unit 250 moves in the direction of arrow C.
Specifically, when the adjuster 258 is raised, the motor side end of the long lens unit 250 is raised against the urging force of the first leaf spring 261. The long lens unit 250 rotates clockwise in the figure with the support base 266 as a fulcrum, and changes its posture. When the adjuster 258 is lowered, the motor side end of the long lens unit 250 is lowered by the urging force of the first leaf spring 261.
Thereby, the long lens unit 250 rotates counterclockwise in the figure with the support base 266 as a fulcrum, and changes its posture. In this scanning line adjustment apparatus, the same operation as that in the normal image forming operation is performed on the photosensitive member that is the object of light irradiation at a predetermined timing to form a latent image of a predetermined tilt adjustment pattern. Then, the inclination adjustment pattern latent image is developed into an inclination adjustment pattern by the same operation as that in the normal image forming operation, and the inclination adjustment pattern is detected by a pattern sensor (optical sensor). Based on the detection result, the posture of the long lens unit 250 is changed by controlling the rotation angle of the drive motor 256 so that the inclination of the inclination adjustment pattern becomes an appropriate inclination. Thereby, the inclination of the scanning line on the photosensitive member can be adjusted to an appropriate one.

  In an image forming apparatus equipped with a scanning line adjustment device, the inclination adjustment unit generally adjusts the inclination of the scanning line when a predetermined number of sheets are printed when the image forming apparatus is activated or during continuous printing. However, this is limited to a predetermined case, such as when the rise value of the temperature sensor that monitors the temperature inside the apparatus becomes a set value or more.

  In the scanning line adjustment apparatus shown in FIG. 17A, when the temperature of the surrounding environment of the long lens 251 rises between the time when the scanning line is adjusted and the time when the next adjustment is performed, the long lens is adjusted. The height of 251 extends due to thermal expansion. On the other hand, since the adjuster 258 is generally formed of a metal member, there is almost no elongation due to thermal expansion even when the temperature of the surrounding environment rises.

  FIG. 17A shows a state before the long lens 251 is thermally expanded. For convenience of explanation, it is assumed that the long lens unit 250 is kept horizontal. When the temperature of the surrounding environment rises, as shown in FIG. 17B, the long lens 251 thermally expands, but the adjuster 258 formed of a metal member hardly thermally expands. It rotates in the direction of arrow D around the support base 266. And as shown in FIG.17 (c), the elongate lens unit 250 inclines right shoulder upward in the figure. If the unintentional tilt occurs in the long lens unit 250 due to the thermal expansion of the long lens 251, the scanning line tilts as much as the long lens unit 250 tilts.

  In the so-called tandem type color image forming apparatus, when the inclination of the scanning line between the latent image carriers is shifted, this appears as a color shift. In the scanning line adjustment device corresponding to each scanning line, the temperature fluctuation around the scanning line adjustment device is different. For this reason, in the scanning line adjustment apparatus corresponding to each scanning line, the unintended inclination of the long lens unit 250 due to the thermal expansion of the long lens 251 is also different, and the inclination of the scanning line between the latent image carriers is different. This will appear as color misregistration. In order to meet the demand for higher image quality, the unintentional inclination of the long lens unit 250 caused by the thermal expansion of the long lens 251 must be made as small as possible in order to further reduce the amount of color misregistration. .

  However, in the configuration of the scanning line adjustment apparatus shown in FIG. 17A, in order to reduce the unintended inclination of the long lens unit 250 caused by the thermal expansion of the long lens 251, the inclination adjustment of the scanning line is performed. We must increase the number of times. However, for example, when a large number of sheets must be printed, if the number of scan line tilt adjustments is increased, the time required for the adjustment becomes longer, which results in downtime of the apparatus. That is, if the number of scan line tilt adjustments is increased, the need for shortening the time required for printing cannot be satisfied.

The present invention has been made in view of the above background, and its object is without increasing the number of times of performing the tilt adjustment of the scanning line, can Ru optical scanning device and reducing unintended tilt of the long lens unit An image forming apparatus is provided.

In order to achieve the above object, the invention of claim 1 is directed to a light source, scanning means for irradiating the light irradiation target with light irradiated from the light source and scanning the light irradiation target, and from the light source to the light irradiation target. In an optical scanning apparatus provided with a scanning optical system provided on the optical path and configured to adjust the bending and inclination of the scanning line, the scanning line adjustment unit changes its attitude with respect to the scanned light. The tilt variation member is provided, comprising: a tilt variation member that changes the tilt of the scanning line on the light irradiation target irradiated with the light; and a fulcrum portion that serves as a fulcrum when the tilt variation member rotates. A support member; an abutting member that abuts on the tilt varying member; a displacement means for displacing the abutting member to rotate the tilt varying member; and the tilt variation in a direction in which the tilt varying member rotates. A biasing means for biasing the member; Has, by adjusting the amount of displacement of the contact member by the displacement means to adjust the orientation of the tilt change member, between the abutment member and the tilt variation member, said line than the contact member A thermal expansion member formed of a material having a large expansion coefficient, and a value of a product of a length of the thermal expansion member in a displacement direction of the contact member and a linear expansion coefficient of the thermal expansion member; The thermal expansion member in which k satisfies 0 <k <2, where k is a value obtained by dividing the length of the inclination variation member in the displacement direction by the product of the linear expansion coefficient of the inclination variation member. The scanning optical system has two or more optical paths, the scanning line adjusting means is used for at least one of the optical paths, and the thermal expansion member of the scanning line adjusting means corresponding to each optical path includes: Responding to the temperature distribution in the surrounding environment of the scanning line adjusting means. Te, the value of k is characterized in that different ones were selected.

  The unintended inclination of the long lens unit can be reduced without increasing the number of times of adjusting the inclination of the scanning line.

1 is a schematic configuration diagram illustrating a printer according to an embodiment. FIG. 2 is a schematic configuration diagram of an image forming station of the printer. FIG. 2 is a schematic configuration diagram of an optical writing unit of the printer. The perspective view of the scanning line adjustment apparatus mounted in the same optical writing unit. The perspective view from the other direction of the scanning line adjustment apparatus. Explanatory drawing of the inclination adjustment means of the long lens unit of the scanning line adjustment apparatus. The expansion block diagram of the free end part vicinity of the elongate lens unit. The block diagram which shows the bending adjustment mechanism of the elongate lens unit. Explanatory drawing of the method of the bending adjustment of the same long lens unit. Explanatory drawing of the attachment position of the thermal expansion member in the same long lens unit. Explanatory drawing of the modification of the same thermal expansion member. Explanatory drawing of the other modification of the thermal expansion member. The block diagram which shows the support mechanism by the side of the edge part of the same elongate lens unit. Explanatory drawing of the method of inclination adjustment of the same long lens unit. Explanatory drawing of an effect | action of the thermal expansion member in the same long lens unit. Explanatory drawing of the scanning line position on the photoconductor when the same thermal expansion member is used. Explanatory drawing of the malfunction which generate | occur | produces in the specific structure of the conventional optical scanning device.

  Hereinafter, an embodiment in which the present invention is applied to a printer as an image forming apparatus will be described. In the present embodiment, a so-called intermediate transfer type tandem image forming apparatus will be described as an example, but the present invention is not limited to this.

FIG. 1 is a schematic configuration diagram illustrating a printer according to the present embodiment.
The printer includes an apparatus main body 1 and a paper feed cassette 2 that can be pulled out from the apparatus main body 1. In the central portion of the apparatus main body 1, image forming stations 3Y, 3C, and 3C for forming toner images (visible images) of respective colors of yellow (Y), cyan (C), magenta (M), and black (K). 3M, 3K. Hereinafter, the subscripts Y, C, M, and K of the respective symbols indicate members for yellow, cyan, magenta, and black, respectively.

FIG. 2 is a configuration diagram showing a schematic configuration of a yellow (Y) imaging station. The other image forming stations have the same configuration.
As shown in FIGS. 1 and 2, the image forming stations 3Y, 3C, 3M, and 3K include drum-shaped photoconductors 10Y, 10C, 10M, and 10K as latent image carriers that rotate in the direction of arrow A in the drawing. ing. Each of the photoreceptors 10Y, 10C, 10M, and 10K includes an aluminum cylindrical substrate having a diameter of 40 mm and an OPC (organic photo semiconductor) photosensitive layer that covers the surface of the photoreceptor.

  Each of the image forming stations 3Y, 3C, 3M, and 3K has charging devices 11Y, 11C, 11M, and 11K that charge the photoconductor around the photoconductors 10Y, 10C, 10M, and 10K, and a latent image formed on the photoconductor. Developing devices 12Y, 12C, 12M, and 12K as developing means for developing an image, and cleaning devices 13Y, 13C, 13M, and 13K for cleaning residual toner on the photoreceptor are provided.

Below each image forming station 3Y, 3C, 3M, 3K, an optical writing unit 4 as an optical writing means, which is an optical scanning device that can irradiate the photoconductors 10Y, 10C, 10M, 10K with the writing light L. It has.
Above each of the image forming stations 3Y, 3C, 3M, and 3K, an intermediate transfer unit 5 including an intermediate transfer belt 20 to which a toner image formed by each of the image forming stations 3Y, 3C, 3M, and 3K is transferred is provided. ing. Further, a fixing unit 6 is provided for fixing the toner image transferred to the intermediate transfer belt 20 to the transfer paper P as a recording material.

  At the upper part of the apparatus main body 1, toner bottles 7Y, 7C, 7M, and 7K that store toners of respective colors of yellow (Y), cyan (C), magenta (M), and black (K) are loaded. The toner bottles 7 </ b> Y, 7 </ b> C, 7 </ b> M, and 7 </ b> K are configured to be detachable from the apparatus main body 1 by opening a paper discharge tray 8 formed on the upper part of the apparatus main body 1.

  The optical writing unit 4 deflects writing light (laser light) L emitted from a laser diode as a light source by a polygon mirror or the like, and irradiates it while scanning on the photoconductors 10Y, 10C, 10M, and 10K. Detailed description of the optical writing unit 4 will be described later.

  The intermediate transfer unit 5 includes an intermediate transfer belt 20, primary transfer rollers 24Y, 24C, 24M, and 24K that transfer toner images formed on the photoreceptors 10Y, 10C, 10M, and 10K to the intermediate transfer belt 20, and an intermediate transfer belt. A secondary transfer roller 25 that transfers the toner image transferred onto the transfer paper P, and a belt cleaning device 26 that cleans the transfer residual toner on the intermediate transfer belt 20 that has not been transferred onto the transfer paper P. ing. The intermediate transfer belt 20 is wound around a driving roller 21, a tension roller 22, and a driven roller 23, and is driven to rotate counterclockwise in the drawing at a predetermined timing.

A process of obtaining a color image in the printer having the above configuration will be described.
In the image forming stations 3Y, 3C, 3M, and 3K, the photoreceptors 10Y, 10C, 10M, and 10K are uniformly charged by the charging devices 11Y, 11C, 11M, and 11K. Thereafter, the optical writing unit 4 scans and exposes the laser light L based on the image information to form latent images on the surfaces of the photoreceptors 10Y, 10C, 10M, and 10K.

  The latent images on the photoconductors 10Y, 10C, 10M, and 10K are developed with toners of the respective colors carried on the developing rollers 15Y, 15C, 15M, and 15K of the developing devices 12Y, 12C, 12M, and 12K, and can be used as toner images. Visualized.

  The toner images on the photoreceptors 10Y, 10C, 10M, and 10K are sequentially transferred onto the intermediate transfer belt 20 that is rotated counterclockwise by the action of the primary transfer rollers 24Y, 24C, 24M, and 24K. The image forming operation of each color at this time is shifted in timing from the upstream side in the moving direction of the intermediate transfer belt 20 toward the downstream side so that the toner image is transferred to the same position on the intermediate transfer belt 20. Executed.

  The surfaces of the photoreceptors 10Y, 10C, 10M, and 10K after the completion of the primary transfer are cleaned by the cleaning blades 13a of the cleaning devices 13Y, 13C, 13M, and 13K, and are prepared for the next image formation. The toner filled in the toner bottles 7Y, 7C, 7M, and 7K is placed in the developing devices 12Y, 12C, 12M, and 12K of the image forming stations 3Y, 3C, 3M, and 3K by a conveyance path (not shown) as necessary. A fixed amount is supplied.

  The transfer paper P in the paper feed cassette 2 is conveyed into the apparatus main body 1 by a paper feed roller 27 disposed in the vicinity of the paper feed cassette 2, and a secondary transfer section at a predetermined timing by a registration roller pair 28. It is conveyed to. Then, the toner image formed on the intermediate transfer belt 20 is transferred to the transfer paper P in the secondary transfer portion.

  The transfer paper P onto which the toner image has been transferred passes through the fixing unit 6 to be fixed, and is discharged to the paper discharge tray 8 by the discharge roller 29. Similar to the photoconductor 10, the transfer residual toner remaining on the intermediate transfer belt 20 is cleaned by a belt cleaning device 26 that contacts the intermediate transfer belt 20.

The configuration of the optical writing unit 4 will be described in detail.
FIG. 3 is an explanatory diagram showing the configuration of the optical writing unit 4 in the present embodiment.
The optical writing unit 4 includes two polygon mirrors 41a and 41b having a regular polygonal column shape. The polygon mirrors 41a and 41b have reflection mirrors on their side surfaces, and are rotated at a high speed around the central axis of the regular polygonal cylinder by a polygon motor (not shown). Thus, when writing light (laser light) from a laser diode (light source) (not shown) is incident on the side surface, the laser light is deflected and scanned.

  In addition to the polygon mirrors 41a and 41b, the optical writing unit 4 is provided with sound-insulating glasses 42a and 42b for the sound-proofing effect of the polygon motor, and polygon scanning mirrors 41a and 41b that perform equiangular motion of laser scanning at a constant velocity straight line. Fθ lenses 43a and 43b that change into motion, and mirrors 44a, 44b, 44c, 44d, 46a, 46b, 46c, 46d, 47a, 47b, 47c, and 47d that guide laser light to the photoreceptors 10Y, 10C, 10M, and 10K. And long lens units 50a, 50b, 50c, and 50d as tilt variation members, and dust-proof glasses 48a, 48b, 48c, and 48d that prevent dust and the like from falling into the housing. Note that reference numerals La, Lb, Lc, and Ld in FIG. 3 indicate the optical paths of the writing light applied to the respective photoreceptors 10Y, 10C, 10M, and 10K.

The configuration of the scanning line adjustment device that adjusts the inclination of the scanning line by the optical writing unit 4 will be described.
The scanning line adjustment apparatus in this embodiment can adjust not only the inclination of the scanning line but also the bending of the scanning line.
In the present embodiment, the bending of the scanning line is adjusted by forcibly deforming the long lenses of the long lens units 50a, 50b, 50c, and 50d. On the other hand, the inclination of the scanning line is adjusted by changing the postures of the long lens units 50a, 50b, 50c, and 50d. In the present embodiment, a mechanism for adjusting the bending of the scanning line is provided in all the long lens units 50a, 50b, 50c, and 50d.

  A mechanism for adjusting the inclination of the scanning line is provided in the long lens units 50a, 50b, and 50c corresponding to the photoreceptors 10Y, 10C, and 10M of yellow (Y), cyan (C), and magenta (M). The long lens unit 50d corresponding to black (K) is not provided. Hereinafter, the long lens unit 50a corresponding to the yellow (Y) photoreceptor 10Y will be described as an example. However, in the following description, the color code is omitted.

FIG. 4 is a perspective view of the long lens unit 50. FIG. 5 is a perspective view of the long lens unit 50 from another direction.
The long lens unit 50 includes a long lens 51 that corrects surface tilt of the polygon mirrors 41 a and 41 b, a bracket 52 that holds the long lens 51, and an elastic pressure for holding and adjusting the long lens 51 and the bracket 52. The bending adjustment leaf spring 53 which is a member, the first and second leaf springs 61 and 62 as urging means, the bending adjustment screw 65 for adjusting the bending of the long lens 51, and the heat of the long lens 51 It comprises a thermal expansion member 70 for adjusting the scan line inclination due to expansion, smooth surface members 63 and 64 as friction coefficient reducing means, and the like.

  6A is a perspective view of the tilt adjusting unit, and FIG. 6B is a cross-sectional view of the tilt adjusting unit. The inclination adjusting means includes a drive motor 56 as a displacement means, a drive motor holder 57, and an adjuster 58 as a contact member. The output shaft of the drive motor 56 is provided with a screw portion, and an adjuster 58 is screwed to the screw portion. The adjuster 58 has a D-shaped cross section and is inserted into the D-shaped adjuster insertion port of the drive motor holder 57. As a result, the adjuster 58 is restricted in rotational movement by the adjuster insertion port, and does not rotate even when the output shaft of the drive motor 56 rotates. The adjuster 58 is moved up and down by being screwed by the output shaft.

  When attaching the long lens 51 to the bracket 52, as shown in FIG. 7A, the long lens 51 is brought into contact with the contact portions 52a provided near both ends in the longitudinal direction of the bracket 52. The long lens 51 is temporarily positioned on the bracket 52. Thereafter, as shown in FIG. 7B, the long lens 51 and the bracket 52 are sandwiched between the U-shaped fixing leaf springs 54 and 55, and are fixed at both ends in the longitudinal direction.

  As shown in FIG. 8, a screw hole is provided in a portion of the top surface of the bracket 52 where the bending adjustment leaf spring 53 is attached, and the bending hole inserted through the hole of the bending adjustment leaf spring 53 is provided in this screw hole. An adjusting screw 65 is attached. A projection 51b is provided at the center of the long lens 51 in the longitudinal direction, and the claw of the bending adjustment leaf spring 53 is hooked on the projection 51b. Thus, the bracket 52 is sandwiched between the bending adjustment leaf spring 53 and the long lens 51.

  The long lens 51 is held by the bracket 52 in a state in which the vicinity of both ends in the longitudinal direction is regulated by the contact portions 52a of the bracket 52 and the central portion in the longitudinal direction is pulled toward the bracket 52 by the bending adjustment leaf spring 53. Is done. As a result, the long lens 51 is pressed against the top surface side of the bracket 52 as shown in FIG. 9 by the contact portion 52a and the urging force of the fixing plate springs 54 and 55 and the bending adjustment plate spring 53. And is held by the bracket 52 in a bent state.

  As shown in FIG. 10, the thermal expansion member 70 is attached to the back surface of the top surface of one end portion in the longitudinal direction of the bracket 52 (end portion on the motor side). The thermal expansion member 70 is formed of a resin member, for example. The thermal expansion member 70 is attached to the bracket 52 by a fastening member such as a screw. As shown in FIG. 11, the thermal expansion member 70 may be formed in a U shape so that the thermal expansion member 70 is attached so as to sandwich the bracket 52. In addition, as shown in FIG. 12, the thermal expansion member 70 may be formed so as to be fitted to a guide provided on the bracket 52. The operation when the thermal expansion member 70 is attached will be described in detail later.

  As shown in FIG. 10, the long lens unit 50 assembled in this way has a central portion in the longitudinal direction on the bottom surface of the long lens 51 (surface opposite to the top surface of the bracket 52) as a housing. It is placed on a support base 66 as a fixed semi-cylindrical support member. Further, the drive motor holder 57 holding the drive motor 56 is fixed to the housing. Then, the top portion of the adjuster 58 screwed into the screw portion of the motor shaft of the drive motor 56 is brought into contact with the thermal expansion member 70 attached to the bracket 52.

A protrusion 51 b is provided at the end of the long lens 51 on the motor side. As shown in FIG. 13, one of the two side surfaces orthogonal to the optical path L in the projection 51b abuts on the fixing portion 67 of the housing, and the other contacts the first unit supporting leaf spring 59 fixed to the housing. Touch. With such a configuration, the motor side end of the long lens 51 is positioned in a state of being pressed against the fixing portion 67 of the housing by the first unit supporting plate spring 59.
A protrusion 51 a is also provided at the end of the long lens 51 opposite to the end on the motor side (hereinafter referred to as “free end”). As shown in FIG. 13, one of the two side surfaces orthogonal to the optical path L of the projection 51a also abuts against the fixing portion 67 of the housing, and the other contacts the second unit supporting leaf spring 60 fixed to the housing. Touch.
With such a configuration, the free end portion of the long lens 51 is positioned in a state where it is pressed against the fixing portion 67 of the housing by the second unit supporting leaf spring 60. In this way, the both ends of the long lens 51 are pressed against the fixing portion 67 of the housing by the first unit supporting plate spring 59 and the second unit supporting plate spring 60, so that the long lens unit 50 has an optical path. Movement in the direction of L is restricted.

  As shown in FIG. 10, the first plate spring 61 and the second plate spring 62 fixed to the housing are in contact with both ends in the longitudinal direction of the top surface of the bracket 52. Due to the urging force of the first leaf spring 61 and the second leaf spring 62, the top surface of the bracket 52 receives a force that is pushed down toward the bottom surface. As a result, the long lens unit 50 includes the adjuster 58, the first plate spring 61, the second plate spring 62, and the support in the direction (vertical direction) orthogonal to both the longitudinal direction of the long lens 51 and the direction of the optical path L. It is held by a base 66.

A method of adjusting the curve of the scanning line in this embodiment will be described.
The scanning line bending adjustment is performed when the printer is shipped. A specific adjustment method is as follows. In a state where the bend adjusting screw 65 is not tightened, as shown in FIG. 9, the longitudinal center portion of the long lens 51 is urged toward the top surface of the bracket 52 by the bend adjusting leaf spring 53. When the bend adjusting screw 65 is tightened from this state, the apex of the bend adjusting screw 65 comes into contact with the central portion in the longitudinal direction of the long lens 51, and the distance between this portion and the top surface of the bracket 52 increases. Both ends of the long lens 51 in the longitudinal direction are fixed to the bracket 52 by fixing plate springs 54 and 55, and the rigidity of the long lens 51 is lower than that of the bracket 52. Therefore, by tightening the bend adjustment screw 65, the long lens 51 is deformed from a state bent in the longitudinal direction to a straight state. The degree of bending of the scanning line by the laser light passing through the long lens 51 changes according to the amount of bending of the long lens 51. Therefore, by adjusting the tightening amount of the bend adjustment screw 65, it is possible to correct the bend of the scanning line that was initially generated.

A method of adjusting the inclination of the scanning line in this embodiment will be described.
The inclination of the scanning line is adjusted at the time of shipment of the printer, and at a predetermined timing such as a timing when the number of prints reaches a predetermined number or a timing when a user instruction is received during operation of the printer. When the inclination of the scanning line is adjusted in the printer shown in FIG. 1, first, a latent image of a predetermined inclination adjustment pattern is displayed on each of the photoconductors 10Y, 10C, 10M, and 10K by the same operation as in a normal image forming operation. Form an image. Then, the inclination adjustment pattern latent image of each color is developed to form an inclination adjustment pattern (toner image) and transferred to the intermediate transfer belt 20 in the same operation as in a normal image forming operation. Thereafter, the inclination adjustment pattern of each color transferred to the intermediate transfer belt 20 is detected by a pattern sensor (optical sensor) (not shown). Based on the detection result, each positional deviation amount between the black (K) inclination adjustment pattern and the other color (Y, C, M) inclination adjustment patterns is grasped. Then, the inclination amount of the scanning line for the other color (Y, C, M) with respect to the scanning line for black (K), which can minimize the grasped positional deviation amount, is calculated, and the result is an attitude adjustment not shown It outputs to the inclination control part which is a means.

FIG. 14 is an explanatory diagram of a method for adjusting the inclination of the scanning line in the present embodiment.
The tilt control unit controls the rotation angle of the drive motor 56 based on the calculation result. As the drive motor 56 rotates, the adjuster 58 attached to the rotating shaft of the drive motor 56 moves up and down, and the motor side end of the long lens unit 50 moves in the direction of arrow C in FIG. Specifically, when the adjuster 58 rises, the motor side end of the long lens unit 50 rises against the urging force of the first plate spring 61. As a result, the long lens unit 50 rotates clockwise in FIG. 14 with the support base 66 as a fulcrum, and changes its posture. On the other hand, when the adjuster is lowered, the motor side end of the long lens unit 50 is lowered by the urging force of the first leaf spring 61. Accordingly, the long lens unit 50 rotates counterclockwise in FIG. 14A with the support base 66 as a fulcrum, and changes its posture.

  When the posture of the long lens unit 50 changes in this way, the position where the laser light L enters the incident surface of the long lens 51 changes. The long lens 51 in this embodiment is long when the incident position of the laser beam L with respect to the incident surface of the long lens 51 changes in a direction (vertical direction) orthogonal to the longitudinal direction of the long lens 51 and the direction of the optical path. It has a characteristic that the angle (emitting angle) with respect to the vertical direction of the laser light emitted from the emitting surface of the scale lens 51 changes. Due to this characteristic, when the posture of the long lens unit 50 is changed by the adjuster 58, the emission angle of the laser light emitted from the emission surface of the long lens 51 is changed accordingly. As a result, the photosensitive member by this laser light is changed. The slope of the upper scan line changes. For example, in the scanning line inclination adjustment, as shown in FIG. 14B, when the drive amount of the drive motor 56 is operated so that the rotation angle of the long lens unit 50 is α, FIG. As shown in FIG. 4, the scanning line moves to the adjusted scanning line B, which is inclined by the rotation angle α from the scanning line A before adjustment.

The operation when the thermal expansion member 70 is attached will be described below.
FIG. 15 is a diagram illustrating the action of the thermal expansion member 70 when the temperature of the surrounding environment rises.
When the height of the long lens 51 is L1, the height of the thermal expansion member 70 is L2, the linear expansion coefficient of the long lens 51 is a1, and the linear expansion coefficient of the thermal expansion member 70 is a2, the temperature of the surrounding environment is ΔT. The height extension ΔL1 of the long lens 51 and the height extension ΔL2 of the thermal expansion member 70 when only the change is made can be expressed by the following equations, respectively.
ΔL1 = a1 × L1 × ΔT
ΔL2 = a2 × L2 × ΔT

The ratio value k between the height extension ΔL1 of the long lens 51 and the height extension ΔL2 of the thermal expansion member 70 can be expressed by the following equation.
k = (a2 × L2 × ΔT) / (a1 × L1 × ΔT)
The characteristic of the thermal expansion member 70 can be defined by the value of k.

  FIG. 15A shows a state before the temperature of the surrounding environment rises, and FIGS. 15B to 15D show a state when the temperature of the surrounding environment rises by ΔT. . 15B shows a case where k = 1, FIG. 15C shows a case where 0 <k <1, and FIG. 15D shows a case where 1 <k <2. In order to simplify the explanation, it is assumed that the long lens unit 50 is in a horizontal state in FIG.

  In FIG. 15B, since k = 1, ΔL1 and ΔL2 are equal. The position of the long lens unit 50 rises by the thermal expansion ΔL1 of the height of the long lens 51, but the height of the thermal expansion member 70 also extends by the same length ΔL1 (= ΔL2) due to thermal expansion. The lens unit 50 is kept in a horizontal state.

  In FIG. 15C, since 0 <k <1, ΔL1> ΔL2. The position of the long lens unit 50 increases by the thermal expansion ΔL1 of the height of the long lens 51, but the thermal expansion of the thermal expansion member 70 is ΔL2, which is smaller than ΔL1, so that the long lens The unit 50 rotates counterclockwise around the support base 66 with respect to the horizontal position and tilts.

  In FIG. 15D, since 1 <k <2, ΔL1 <ΔL2. The position of the long lens unit 50 is increased by the thermal expansion ΔL1 of the height of the long lens 51, but the thermal expansion of the thermal expansion member 70 is ΔL2, which is larger than ΔL1, so that the long lens The unit 50 rotates clockwise around the support base 66 with respect to the horizontal position and tilts.

  In the thermal expansion member 70 in which the value k of the thermal expansion member 70 shown in FIG. 15B is k = 1, the long lens unit 50 is unintentionally inclined due to the thermal expansion of the long lens 51. Does not occur at all. For this reason, it is preferable to use the thermal expansion member 70 whose value of k is as close as possible to 1. However, it is difficult to stably manufacture the thermal expansion member 70 with k≈1 in terms of processing accuracy and manufacturing cost.

  In the case of k ≠ 1, an unintended inclination of the long lens unit 50 due to the thermal expansion of the long lens 51 occurs. However, if the value of k of the thermal expansion member 70 shown in FIGS. 15C and 15D is in the range of 0 <k <2, the thermal expansion can be obtained by using this. As compared with the case where the member 70 is not used, the tilt amount of the long lens unit 50 can be reduced. Therefore, if the thermal expansion member 70 satisfies 0 <k <2, the unintended inclination of the long lens unit 50 due to the thermal expansion of the long lens 51 can be reduced to a level that does not hinder practical use. .

Inside the optical writing unit 4, the temperature fluctuation of the surrounding environment is not necessarily the same. For example, in the layout of the optical writing unit 4 shown in FIG. 16A, among the colors of yellow (Y), cyan (C), magenta (M), and black (K), the frequently used black ( In the optical path D in which the photoconductor 10K for toner image formation of K) is nearby, the temperature rises more easily than the other optical paths (optical paths A, B, C). For this reason, in the long lens unit 50d in the optical path D, the inclination due to the thermal expansion of the long lens 51 becomes large.
Considering the case where the printer is continuously operated, the influence of heat generated by the polygon mirrors 41a and 41b rotating at high speed is very large. Therefore, in the long lens units 50b and 50c in the optical paths B and C around this, The inclination due to the thermal expansion of the long lens 51 becomes large. Therefore, at least in the scanning line adjustment apparatus for the optical path D, the thermal expansion member 70 is used. In consideration of the case where the printer is continuously operated, the thermal expansion member 70 is also used in the scanning line adjustment devices for the optical paths B and C.
Thus, among the plurality of optical paths, at least in the scanning line adjustment device of the optical path in which the ambient temperature is likely to rise, the thermal expansion member 70 is used, resulting in the thermal expansion of the long lens 51. It is possible to reduce the deviation of the inclination of the scanning line between the photosensitive members.

  When the optical writing unit 4 has a plurality of optical paths, the thermal expansion member 70 may be used in the scanning line adjustment devices for all the optical paths. For example, in the optical writing unit 4 shown in FIG. 16A, the thermal expansion member 70 is attached to the corresponding long lens units 50a, 50b, 50c, and 50d for all of the optical paths A, B, C, and D. Good. However, among the plurality of optical paths, the long lens units 50b and 50c are used in the optical path where the ambient temperature of the corresponding long lens unit 50 is likely to rise (for example, the optical paths B, C, and D in FIG. 16A). In order to make the inclination of 50d as small as possible, it is preferable to select the thermal expansion member 70 with the value of k as close to 1 as possible. By doing in this way, the shift | offset | difference of the inclination of the scanning line between each photoreceptor resulting from the thermal expansion of the elongate lens 51 can be made small.

  When the scanning optical system has two or more optical paths, an optical path group in which the moving direction of the scanning line position on the photosensitive member that is moved by the scanning line adjusting operation by the scanning line adjusting unit is the rotational direction of the photosensitive member, and the photosensitive member The thermal expansion member 70 may be used in the scanning line adjustment device in any one of the optical path groups opposite to the rotation direction of the body. The merit of doing this will be described below.

For example, in FIG. 16A, when the thermal expansion member 70 is used in the scanning line adjustment means, the optical paths B and C are in the direction in which the scanning line position on the photosensitive member moves due to the adjustment action by the thermal expansion member 70. The optical path group is the rotation direction of the photosensitive member. In addition, when the thermal expansion member 70 is used in the scanning line adjustment means, the optical paths A and D are such that the scanning line position on the photoconductor moves due to the adjustment by the thermal expansion member 70 is the rotation direction of the photoconductor. It is a group of optical paths that are reversed.
The writing light emitted from the light source passes through the long lens unit 50 and then is reflected by a plurality of mirrors and reaches the photosensitive member. In the optical paths B and C, after passing through the long lens units 50b and 50c, they are reflected by the mirror a plurality of times (twice). On the other hand, in the optical paths A and D, after passing through the long lens units 50a and 50d, they are reflected by an odd number of times (three times) mirrors. For this reason, even if the long lens unit 50 is similarly tilted by the action of the thermal expansion member 70, the position of the scanning line on the photosensitive member is adjusted in the reverse direction. This will be specifically described below.

FIG. 16B shows a long length when the thermal expansion member 70 is not used and when the respective thermal expansion members 70 having k values of k = 1, 0 <k <1, and 1 <k <2 are used. The inclination of the lens unit 50 is shown respectively. For simplicity, it is assumed that the effect of adjusting the inclination of the long lens unit 50 when the same thermal expansion member 70 is used in each optical path is the same.
FIG. 16C shows a photoconductor in the case where the thermal expansion member 70 having different values of k (0 <k <1, k = 1, 1 <k <2) is used in the scanning line adjustment apparatus for the optical path A. It is the figure which showed the position of the scanning line on 10Y, respectively. When the thermal expansion member 70 is not used, the position of the scanning line on the photoreceptor 10Y is P1a. When the thermal expansion member 70 is used, the position of the scanning line on the photoconductor 10Y is P2a when the value of k of the thermal expansion member 70 is 0 <k <1, P3a when k = 1, and 1 <k <2. Then, it is P4a.
FIG. 16D shows a case where the thermal expansion member 70 having different k values (0 <k <1, k = 1, 1 <k <2) is used in the scanning line adjustment device for the optical path B. It is the figure which each showed the position of the scanning line on the photoreceptor 10C. When the thermal expansion member 70 is not used, the position of the scanning line on the photoconductor 10C is P1b. When the thermal expansion member 70 is used, the position of the scanning line on the photoreceptor 10Y is P2b when the value of k of the thermal expansion member 70 is 0 <k <1, P3b when k = 1, and 1 <k <2. Then, it is P4b.

In the optical paths A and B, when the thermal expansion member 70 with the scanning line adjustment device k = 1 is used, the position of the scanning line on the photoreceptor 10Y becomes a desired position. That is, the positions of P3a and P3b on the respective photoconductors 10Y and 10C coincide.
In the optical path A, the position P1a when the thermal expansion member 70 is not used and the position P2a when the thermal expansion member 70 of 0 <k <1 is used in the rotation direction of the photoconductor 10Y with respect to the desired position P3a. It's off. Further, the position P4a when the thermal expansion member 70 of 1 <k <2 is used is shifted in the direction opposite to the rotation direction of the photoconductor 10Y.
On the other hand, in the optical path B, the position P1b when the thermal expansion member 70 is not used and the position P2b when the thermal expansion member 70 of 0 <k <1 are used with respect to the desired position P3b are rotations of the photoconductor 10C. The direction is shifted in the opposite direction. Further, the position P4b when the thermal expansion member 70 of 1 <k <2 is used is shifted in the rotation direction of the photoconductor 10C.
That is, when the thermal expansion member 70 is not used in either of the optical path A and the optical path B, it is shifted to the opposite side with respect to a desired position on the photosensitive member. Further, in both the optical path A and the optical path B, the thermal expansion member 70 with 0 <k <1 is used, and in either case, the thermal expansion member 70 with 1 <k <2 is used. It will be shifted to the opposite side to the desired position.

For example, in both the optical path A and the optical path B, when the thermal expansion member 70 of 1 <k <2 is used, the shift of the scanning line position is the sum of the arcs P3a to P4a and the arcs P3b to P4b. On the other hand, when the thermal expansion member 70 of 1 <k <2 is used only for the optical path A, the shift of the scanning line position is an absolute value of the difference between the arcs P3a to P4a and the arcs P3b to P1b. When the thermal expansion member 70 of 1 <k <2 is used only for the optical path B, the shift of the scanning line position is an absolute value of the difference between the arcs P3a to P1a and the arcs P3b to P4b. Depending on the value of k of the thermal expansion member 70 used and the temperature fluctuation of the surrounding environment, each of the photoconductors is used rather than using the thermal expansion member 70 in either the optical path A or the optical path B. In some cases, the shift of the scanning line position can be reduced.
As described above, the optical path group in which the moving direction of the scanning line position on the photosensitive member that is moved by the scanning line adjusting operation by the scanning line adjusting unit is the rotating direction of the photosensitive member, and the optical path group that is opposite to the rotating direction of the photosensitive member. The thermal expansion member 70 may be used in the scanning line adjustment device in any one of the optical path groups.

What has been described above is an example, and the present invention has a specific effect for each of the following aspects.
(Aspect A)
An inclination changing member that changes the inclination of a scanning line on a light irradiation target irradiated with the light by changing a posture with respect to the scanned light, and a fulcrum portion that serves as a fulcrum when the inclination changing member rotates. In addition, a support member that supports the tilt variation member, a contact member that contacts the tilt variation member, a displacement unit that displaces the contact member to rotate the tilt variation member, and the tilt variation member Scanning line adjustment that adjusts the attitude of the tilt varying member by adjusting the amount of displacement of the contact member by the displacing means. In the apparatus, a thermal expansion member formed of a material having a linear expansion coefficient larger than that of the contact member is provided between the inclination varying member and the contact member.
By providing the thermal expansion member 70 made of a material having a larger linear expansion coefficient than the contact member between the inclination change member and the contact member, when the temperature of the surrounding environment rises, Since both of the thermal expansion members 70 are thermally expanded, an unintended inclination amount of the long lens unit 50 can be reduced.

(Aspect B)
In the scanning line adjustment apparatus according to aspect A, the value of the product of the length of the thermal expansion member in the displacement direction of the contact member and the linear expansion coefficient of the thermal expansion member is the inclination in the displacement direction of the contact member. When k is a value obtained by dividing the length of the variable member by the product of the linear expansion coefficient of the tilt variable member, k is 0 <k <2.
The thermal expansion member that satisfies the above conditions was used.
The length of the tilt variation member such as the long lens unit 50 in the displacement direction of the contact member is L1, the linear expansion coefficient is a1, and the length of the thermal expansion member 70 in the displacement direction of the contact member is L2. When the linear expansion coefficient is a2, in the scanning line adjustment device,
k = (a2 × L2) / (a1 × L1)
0 <k <2
By using the thermal expansion member 70 satisfying the above relationship, when the tilt variation member such as the long lens unit 50 is thermally expanded due to a temperature increase in the surrounding environment, the thermal expansion member 70 is Thermal expansion can be achieved by an amount approximately equal to the thermal expansion.

(Aspect C)
A light source, scanning means for irradiating the light irradiation target with the light irradiated from the light source and scanning the light irradiation target, and an optical path from the light source to the light irradiation target are provided to adjust the bending and inclination of the scanning line. In an optical scanning device provided with a scanning optical system composed of a scanning line adjustment means to perform,
The scanning optical system has two or more optical paths, and the scanning line adjustment device according to the aspect A or B is used as at least one of the scanning line adjustment means corresponding to each optical path.
A thermal expansion member provided at a contact position with an abutting member such as an adjuster 58 in the long lens unit 50 when an inclination changing member such as the long lens unit 50 is thermally expanded due to a temperature rise in the surrounding environment. 70 is thermally expanded by an amount substantially equal to the thermal expansion of the long lens unit 50, whereby the unintended inclination of the long lens unit 50 can be prevented. As a result, it is possible to reduce the amount of color misregistration due to the deviation of the inclination of the scanning line between the latent image carriers.

(Aspect D)
In the optical scanning device according to aspect C, the optical path group in which the moving direction of the scanning line position on the latent image carrier that is moved by the scanning line adjustment operation by the scanning line adjustment unit is the rotational direction of the latent image carrier, and the latent image In any one of the optical path groups opposite to the rotation direction of the carrier, the scanning line adjusting device according to the aspect A or B was used as the scanning line investigation means corresponding to each optical path.
The writing light emitted from the light source passes through the long lens unit 50 and then is reflected by a plurality of mirrors and reaches the photosensitive member. An optical path group reflected by the mirror a plurality of times after passing through the long lens unit 50 and an optical path group reflected by the mirror an odd number of times after passing through the long lens unit 50 are caused by the action of the thermal expansion member 70. Even if the long lens unit 50 is tilted in the same manner, the position of the scanning line on the photoreceptor is adjusted in the reverse direction. That is, the value of the ratio of the expansion of the tilt variation member in the displacement direction of the contact member to the expansion of the thermal expansion member in the displacement direction of the contact member with respect to a certain temperature change of the thermal expansion member 70 to be used. Depending on k (when k ≠ 1, especially when k≈2, etc.), the adjustment of the thermal expansion member 70 may not be able to reduce the deviation of the inclination of the scanning line between the latent image carriers. is there. By using the thermal expansion member 70 only in one of the optical path groups in which the positions of the scanning lines on the photosensitive member are adjusted in opposite directions, the value of k of the thermal expansion member 70 to be used is set to k. Even if ≈1 is not set, the deviation of the inclination of the scanning line between the latent image carriers can be reduced.

(Aspect E)
In the optical scanning device of aspect C, among the scanning line adjustment means corresponding to each optical path, at least the scanning line adjustment means in which the temperature fluctuation of the surrounding environment is relatively large is the scanning line adjustment of aspect A or B. A device was used.
In the optical path, the temperature fluctuation of the surrounding environment is relatively large, and the unintended inclination of the long lens unit 50 is increased due to thermal expansion of the long lens unit 50. In a scanning line adjustment apparatus for an optical path in which temperature fluctuations in the surrounding environment are relatively large, the thermal expansion member 70 is used, and the inclination of the unintended long lens unit 50 is reduced, thereby scanning between each latent image carrier. The inclination of the line can be reduced.

(Aspect F)
In the optical scanning device according to aspect C, the scanning line adjustment device according to aspect B is used as the scanning line adjustment unit, and the thermal expansion member of the scanning line adjustment unit corresponding to each optical path includes a periphery of the scanning line adjustment unit. Different k values were selected according to the environmental temperature distribution.
In the thermal expansion member 70 in which the value of k of the thermal expansion member 70 is k = 1, the long lens unit 50 is not tilted. Therefore, between the latent image carriers due to the thermal expansion of the long lens 51. No deviation of the scan line inclination occurs. For this reason, it is preferable to use the thermal expansion member 70 whose value of k is as close as possible to 1. However, it is difficult to stably manufacture the thermal expansion member 70 with k≈1 in terms of processing accuracy and manufacturing cost. In the optical path scanning line adjustment apparatus in which the temperature fluctuation of the surrounding environment is relatively large, the thermal expansion member 70 with k≈1 is selected, and in the other optical path scanning line adjustment apparatuses, the range of 0 <k <2 is satisfied. If the thermal expansion member 70 is appropriately selected, it is possible to reduce the deviation of the inclination of the scanning line between the latent image carriers while suppressing the manufacturing cost of the thermal expansion member 70.

(Aspect G)
A latent image carrier, optical writing means for writing a latent image on the surface of the latent image carrier by irradiating and scanning the surface of the latent image carrier with writing light according to image information, and the optical writing Developing means for developing the latent image formed on the surface of the latent image carrier by the means into a visible image,
In an image forming apparatus for forming an image on the recording material by transferring a visible image on the surface of the latent image carrier directly or indirectly onto the recording material, any one of modes C to F is used as the optical writing unit. One optical scanning device was used.
A thermal expansion member provided at a contact position with an abutting member such as an adjuster 58 in the long lens unit 50 when an inclination changing member such as the long lens unit 50 is thermally expanded due to a temperature rise in the surrounding environment. 70 is thermally expanded by an amount substantially equal to the thermal expansion of the long lens unit 50, whereby the unintended inclination of the long lens unit 50 can be prevented. As a result, it is possible to reduce the amount of color misregistration due to the deviation of the inclination of the scanning line between the latent image carriers.

50 Long lens unit 51 Long lens 52 Bracket 53 Bending adjustment plate springs 54, 55 Fixing plate spring 56 Drive motor 57 Drive motor holder 58 Adjuster 61 First plate spring 62 Second plate spring 63, 64 Lubricating surface member 65 Bending adjustment screw 66 Support base 70 Thermal expansion member

Japanese Patent No. 4951242

Claims (2)

A light source, scanning means for irradiating the light irradiation target with the light irradiated from the light source and scanning the light irradiation target, and an optical path from the light source to the light irradiation target are provided to adjust the bending and inclination of the scanning line. In an optical scanning device provided with a scanning optical system composed of a scanning line adjustment means to perform,
The scanning line adjusting means includes a tilt changing member that changes a tilt of a scanning line on a light irradiation target irradiated with the light by changing a posture with respect to the scanned light, and a tilt changing member that rotates when the tilt changing member rotates. A support member that supports the tilt variation member, a contact member that abuts the tilt variation member, and a displacement that displaces the contact member to rotate the tilt variation member. And a biasing means for biasing the tilt variation member in a direction in which the tilt variation member rotates, and by adjusting a displacement amount of the contact member by the displacement means, Adjust posture ,
A thermal expansion member formed of a material having a larger linear expansion coefficient than the contact member is provided between the inclination changing member and the contact member ,
The value of the product of the length of the thermal expansion member in the displacement direction of the contact member and the linear expansion coefficient of the thermal expansion member is expressed as the length of the inclination variation member in the displacement direction of the contact member and the inclination variation. When the value obtained by dividing by the product of the linear expansion coefficient of the member is k, the thermal expansion member is used, wherein k satisfies 0 <k <2.
The scanning optical system has two or more optical paths, and the scanning line adjusting means is used for at least one of the optical paths.
Optical scanning characterized in that the thermal expansion member of the scanning line adjustment means corresponding to each optical path is selected to have a different k value according to the temperature distribution of the surrounding environment of the scanning line adjustment means. Equipment . A latent image bearing member, a optical writing means for writing a latent image on the latent image bearing member surface by scanning and irradiating the latent image bearing member surface writing light corresponding to image information, the optical writing And developing means for developing the latent image formed on the surface of the latent image carrier to visualize it, and directly or indirectly the visible image on the surface of the latent image carrier on the recording material. In the image forming apparatus for transferring and forming an image on the recording material,
An image forming apparatus using the optical scanning device according to claim 1 as the optical writing unit.

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