JP2010216540A - Reduction gear, image carrier driving device, and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reduction gear capable of restricting an increase of the manufacturing cost, capable of automatically correcting the parallel degree of a rotary shaft between members for transmitting drive with friction, and capable of transmitting the speed reducing drive to an image carrier, more accurately restricting the fluctuation of the rotating speed, and to provide an image carrier driving device and an image forming device. <P>SOLUTION: This reduction gear includes a push regulating means 88, which has a regulating member 87a for regulating deviation of a driving shaft 86 in the rotating direction of a drive transmitting member 85 and which pushes the driving shaft 86 toward the center of rotation of the drive transmitting member 85. Drive is transmitted to the driving shaft 86 from a drive source 81 through a coupling 110. The push regulating means 88 is structured to swing in a direction for restricting force of the driving shaft 86 in the rotary shaft direction in response to the force of the driving shaft 86 in the rotary shaft direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reduction device that reduces the rotational speed of a drive source and transmits it to an image carrier, and an image carrier drive device including the reduction device and an image forming apparatus such as a copying machine, a facsimile machine, and a printer.

  In an image forming apparatus provided with an image carrier such as a photoreceptor, image formation is performed by subjecting the image carrier to a charging process, an exposure process, a development process, a transfer process, and the like according to the rotation of the image carrier. To do. In such an image forming apparatus, a drive source such as a motor for rotationally driving the image carrier is provided, but the rotational speed of the drive source is generally larger than the rotational speed required for the rotation of the image carrier. Therefore, conventionally, reduction gears using gears (for example, see Patent Literature 1 and Patent Literature 2) and reduction gears using planetary rollers (for example, see Patent Literatures 3 to 5) are used.

  With a reduction gear using gears, the rotational speed of the image carrier may vary due to backlash when a rotational load is generated on the image carrier during the above-described steps. There is a problem that may decrease. On the other hand, the speed reduction mechanism using planetary rollers has the advantage that such fluctuations are unlikely to occur because no gear is used, but the problem is that the mechanism is relatively complex and it is difficult to reduce the size and cost. is there.

  As a technique for suppressing fluctuations in the rotational speed of the image carrier in the speed reduction mechanism using gears, a technique using a flywheel is known, and in particular, transmission of drive between the drive side and the driven side, A technique has been proposed in which friction is caused between the peripheral surface of the driving roller and the peripheral surface of the driven roller instead of the gear (see, for example, Patent Document 1 and Patent Document 2). This technique has the advantage that fluctuations in the rotational speed of the flywheel due to backlash are suppressed. Therefore, it is conceivable that the technique of driving transmission by friction is diverted to a reduction gear and the speed is reduced by the rotation ratio between the driving roller and the driven roller. However, the structure in this technology is such that the drive transmission is simply performed by friction between the peripheral surface of the drive roller and the peripheral surface of the driven roller. Therefore, the drive transmission is suppressed while suppressing fluctuations in rotational speed for the following reason. There is a problem that it is difficult to do.

  That is, in order to perform drive transmission by friction, there is a requirement that the driving roller and the driven roller must be in pressure contact with each other in order to ensure frictional force. On the other hand, in order to suppress fluctuations in the rotational speed, there is a requirement that the rotational deviations of the driving roller and the driven roller must be suppressed. These two requirements are in a trade-off relationship.

  In other words, if the driving roller and the driven roller are brought into pressure contact with each other in order to ensure the frictional force, the rotation shafts of these rollers bend, and the rotation of these rollers becomes unstable, resulting in an unstable result. As a result, the rotation speed fluctuates. However, if the driving roller and the driven roller are simply in contact with each other to prevent the deflection of the rotating shaft, or if the pressure contact force of these rollers is weakened, the drive cannot be transmitted, Transmission may be insufficient.

  In view of this, the present applicant has proposed a reduction device, an image carrier driving device, and an image forming apparatus that can reliably perform drive transmission while suppressing fluctuations in rotational speed using frictional drive transmission. Application No. 2008-171609). This speed reduction device includes a pressing member that includes a restricting member for restricting the shift of the drive shaft in the rotation direction of the drive transmission member and presses the drive shaft toward the rotation center of the drive transmission member. According to this configuration, it is possible to prevent drive shaft displacement in the rotation direction of the drive transmission member and reliably perform drive transmission while suppressing fluctuations in the rotation speed.

  However, in the reduction gear configured as described above, if the parallelism between the rotation axis (axis) of the drive shaft and the rotation axis (axis) of the drive transmission member is not maintained, a skew angle is generated between these rotation axes, and the drive Along with the rotation of the shaft, there is a possibility that a shifting force is generated at the contact portion between the drive shaft and the drive transmission member in order to move both in the thrust direction (rotation shaft direction). If there is backlash that can move in the thrust direction between these drive shafts and the drive transmission member, it moves in the thrust direction by this backlash and absorbs the shifting force. When the static frictional force in the thrust direction at the contact portion with the transmission member is exceeded, the slipping occurs and the original position in the thrust direction is returned by the amount of play. When slip occurs in the thrust direction, slip also occurs in the rotation direction, which may cause a deviation in the rotation angle for driving transmission, resulting in fluctuations in rotation speed.

  In order to reduce the shifting force, the degree of parallelism between the rotation shaft of the drive shaft and the rotation shaft of the drive transmission member is improved by increasing the accuracy of each component constituting the reduction gear or increasing the assembly accuracy. This can be dealt with by reducing the deviation and making the skew angle small, but there is a problem that the manufacturing cost increases.

  The present invention suppresses an increase in manufacturing cost and automatically corrects the parallelism of the rotating shaft between the members that perform drive transmission by friction, and decelerates the image carrier while more reliably suppressing fluctuations in the rotational speed. It is an object of the present invention to provide a speed reducer, an image carrier driving device, and an image forming apparatus that can perform drive transmission.

  In order to achieve the above object, a first aspect of the present invention includes a drive shaft that is rotationally driven by a drive source, a drive transmission member that has a circumferential surface in contact with the drive shaft and is rotationally driven by the drive shaft. A reduction device that decelerates the drive from the drive source and transmits it to the image carrier, and includes a restricting member for restricting the displacement of the drive shaft in the rotational direction of the drive transmitting member. A pressure restricting means for pressing the drive shaft toward the rotation center of the drive transmission member; the pressure restricting means holds the drive source, and the drive shaft according to a force in the rotation shaft direction of the drive shaft; It is configured to be swingable in a direction to suppress the force in the direction of the rotation axis.

  The invention according to claim 2 includes a drive shaft that is rotationally driven by the drive source, and a drive transmission member that has a circumferential surface that contacts the drive shaft and is rotationally driven by the drive shaft. A reduction device that decelerates drive and transmits the image to an image carrier, the drive device having a restricting member for restricting the displacement of the drive shaft in the rotational direction of the drive transmitting member. A pressure restricting means for pressing toward the center of rotation, wherein the drive shaft is driven and transmitted from the drive source via a coupling, and the pressure restricting means is driven according to a force in a rotation direction of the drive shaft. It is configured to be swingable in a direction to suppress the force of the shaft in the rotational axis direction.

  According to a third aspect of the present invention, in the speed reduction device according to the first or second aspect, the shaft adjustment swing fulcrum portion having a swing fulcrum of the press restricting means and the shaft adjustment for guiding the swing of the press restricting means. A swing guide portion, and the shaft adjustment swing fulcrum portion is located away from the installation position of the drive shaft in the direction of the reaction force that the drive shaft receives from the drive transmission member when the drive shaft rotates. It is characterized by being provided.

  According to a fourth aspect of the present invention, in the speed reducer according to the third aspect, the shaft adjustment swing fulcrum has a pressure member for pressing the drive shaft toward the rotation center of the drive transmission member. The shaft adjustment swing guide portion includes a press swing support member that serves as a swing support point of the press restricting means for pressing the drive shaft, and a support member that rotatably supports the press swing support member. It is characterized by having.

  According to a fifth aspect of the present invention, in the speed reducer according to the fourth aspect, the support member is formed with a hole through which the pressing rocking fulcrum member is movably engaged when the pressing regulating means swings. It is characterized by.

  According to a sixth aspect of the present invention, in the speed reduction device according to the fourth or fifth aspect, the support member is configured to be deformable in accordance with the swinging of the pressing restricting means.

  A seventh aspect of the present invention is the speed reducer according to the fourth aspect, wherein the pressing and swinging fulcrum member is a roller, and the support member is configured to support the roller. Is.

  According to an eighth aspect of the present invention, in the speed reduction device according to the seventh aspect, the roller is a spherical roller or a cylindrical roller.

  According to a ninth aspect of the present invention, in the speed reducer according to the third aspect, the shaft adjusting swing guide portion includes a pressure member for pressing the drive shaft toward the rotation center of the drive transmission member, A pressure support member that supports the pressure member; and an engaging portion that engages with the pressure support member, wherein the shaft adjustment swing fulcrum portion is the pressure regulating means for pressing the drive shaft. And a support member for rotatably receiving and supporting the pressure swing fulcrum member.

  According to a tenth aspect of the present invention, in the speed reducer according to the ninth aspect, the engagement portion is formed with a hole through which the pressure support member is movably engaged when the pressing restricting means swings. It is characterized by this.

  The invention according to claim 11 is the reduction gear according to any one of claims 1 to 10, wherein the restricting member is provided at a position facing the circumferential surface, and the drive shaft is restricted at this position. And at least two contact points between the restricting member and the drive shaft on a peripheral surface of the drive shaft opposite to the peripheral surface facing the drive transmission member.

  According to a twelfth aspect of the present invention, in the speed reducer according to the eleventh aspect, the position of the contact is determined by the resultant force of the force that the pressing restricting means presses the drive shaft toward the circumferential surface at the contact. The drive shaft is in a position that is in a direction toward the rotation center of the drive transmission member.

  In a thirteenth aspect of the present invention, in the speed reducer according to the eleventh or twelfth aspect, the position of the contact is symmetrical with respect to a straight line connecting the rotation center of the drive shaft and the rotation center of the drive transmission member. It is characterized by being.

  A fourteenth aspect of the present invention is the speed reduction device according to any one of the eleventh to thirteenth aspects, wherein the restricting member is two press-contact rollers that abut against the drive shaft and can be driven to rotate by the drive shaft. It is what.

  According to a fifteenth aspect of the present invention, in the speed reducer according to the fourteenth aspect, the two pressure contact rollers are ball bearings or roller bearings.

  A sixteenth aspect of the present invention is the speed reducer according to any one of the eleventh to thirteenth aspects, wherein the restricting member has a substantially U-shaped, substantially V-shaped or polygonal recess, and the drive is performed in this recess. It abuts on the shaft.

  According to a seventeenth aspect of the present invention, in the reduction gear according to any one of the first to tenth aspects, the restricting member is configured to freely rotate the drive shaft on both sides of the drive transmission member in the axial direction of the drive shaft. The bearing is a supported bearing.

  According to an eighteenth aspect of the present invention, in the speed reduction device according to any one of the first to tenth aspects of the present invention, the restricting member includes the drive shaft and the drive source with respect to the drive transmission member in the axial direction of the drive shaft. Is a bearing that is rotatably supported on the opposite side.

  According to a nineteenth aspect of the present invention, in the speed reducer according to any one of the first to eighteenth aspects, the drive shaft has a flexible portion with a narrowed shaft diameter at a root portion thereof.

  A twentieth aspect of the present invention is the speed reduction device according to any one of the first to nineteenth aspects, further comprising a displacement unit that supports the drive source so as to be displaceable with respect to the non-moving body for supporting the drive source. It is characterized by.

  According to a twenty-first aspect of the present invention, in the speed reducer according to the twentieth aspect, the displacement means includes an elastic member that supports the drive source so as to be displaceable with respect to the non-moving body.

  According to a twenty-second aspect of the present invention, in the speed reducer according to the twentieth or twenty-first aspect, the displacement means is configured to displace the drive source in a first direction in which the pressing restricting means presses the drive shaft against the drive transmission member. It has a biasing member for biasing.

  The invention according to claim 23 is the speed reduction device according to claim 20 or 21, wherein the urging member includes a first urging member for urging the drive source in a first direction, and the drive source. And a second biasing member for biasing the drive source in a second direction opposite to the first direction, and the first biasing member biases the drive source in the first direction. The urging force is characterized in that the second urging member is larger than the urging force that urges the drive source in the second direction.

  According to a twenty-fourth aspect of the present invention, in the speed reducer according to any one of the first to twenty-third aspects, the drive shaft and the drive transmission member are made of metal, and lubrication is provided between the drive shaft and the circumferential surface. It has the lubrication means which makes it the state lubricated with the agent.

  According to a twenty-fifth aspect of the present invention, in the speed reducer according to the twenty-fourth aspect, the lubricant is traction oil.

  According to a twenty-sixth aspect of the present invention, in the reduction gear according to any one of the first to twenty-fifth aspects, a rotational speed detecting means for detecting a rotational speed of the drive transmission member, and the rotational speed detected by the rotational speed detecting means. And a rotational speed control means for controlling the rotational speed of the drive shaft so as to keep constant.

  A twenty-seventh aspect of the invention includes the speed reduction device according to any one of the first to twenty-sixth aspects and the driving source having the driving shaft, and the driving force of the driving source via the driving transmission member. An image carrier driving apparatus that rotationally drives the image carrier.

  According to a twenty-eighth aspect of the invention, there is provided an image forming apparatus having the image carrier driving device according to the twenty-seventh aspect and an image carrier that is rotationally driven by the image carrier driving device.

  According to the present invention, when a force in the rotation axis direction is generated on the drive shaft that is rotationally driven by the drive source, the pressure restricting means that presses the drive shaft toward the drive transmission member swings, thereby The parallelism of both rotation axes is automatically corrected so that the rotation axis and the rotation axis of the drive transmission member are parallel to each other. In addition, the mechanism for swinging the pressure restricting means is lower in cost than the case where the precision of the components of the pressure restricting means is increased or the assembly accuracy is increased in order to make both the rotating shafts parallel. Can be manufactured. Therefore, it is possible to suppress the increase in manufacturing cost, suppress the deviation in the rotation axis direction of the member that performs the drive transmission due to friction, and perform the drive transmission while more reliably suppressing the fluctuation of the rotation speed.

1 is a schematic front view of an image forming apparatus to which the present invention is applied. FIG. 2 is a schematic perspective view of an image carrier, an image carrier driving device and the like provided in the image forming apparatus shown in FIG. 1. FIGS. 3A and 3B are schematic views of the image carrier driving device and the speed reduction device provided in the image carrier driving device shown in FIG. 2, wherein FIG. 3A is a schematic side sectional view, and FIG. FIG. 4 is a block diagram showing a control configuration for performing feedback control in the image carrier driving device and the speed reduction device shown in FIG. 3. FIG. 4 is a schematic top view of the vicinity of the contact portion between the drive shaft and the wheel shown in FIG. 3, wherein (a) shows a pressure member and a skew member in which a skew angle is generated between the rotation shaft of the drive shaft and the rotation shaft of the drive transmission member. (B) is a schematic top view of a state in which the press contact arm swings and the parallelism is automatically corrected, and (c) is a schematic view of the press contact arm with the lower side on the right side. It is a schematic top view of the state which inclined. It is a schematic side view which shows the structural example of the other speed reducer from which the structure of the attachment part of the motor 81 differs from FIG. FIG. 7 is a schematic top view of the vicinity of the contact portion between the drive shaft and the wheel in the speed reducer configured as shown in FIG. 6, wherein FIG. FIG. 4B is a schematic top view of the resulting pressing member in which the lower side inclines to the left side, FIG. 5B is a schematic top view of the state in which the pressure contact roller swings and the parallelism is automatically corrected, and FIG. It is a schematic top view in the state where the lower side in the figure is inclined to the right side. It is the schematic which shows the other structural example of the press control means comprised so that rocking | fluctuation, Comprising: (a) is a schematic front view, (b) is a schematic top view, (c) is a schematic side view. It is the schematic which shows the further another structural example of the press control means comprised so that rocking | fluctuation, Comprising: (a) is a schematic front view, (b) is a schematic top view. It is the schematic using a cylindrical roller as a roller in the structure of FIG. 9, Comprising: (a) is a schematic front view, (b) is a schematic top view. It is the schematic which shows the further another structural example of the press control means comprised so that rocking | fluctuation, Comprising: (a) is a schematic front view, (b) is a schematic top view. It is the schematic front view which showed another structural example of the press control means with which the reduction gear shown in FIG. 3 was equipped. FIG. 12 is a schematic front view showing a configuration example of the support member provided in the pressing restricting means. It is the graph which showed the characteristic of the conventional speed reducer, Comprising: (a) is a time domain, (b) is a graph which showed this characteristic in a frequency domain. It is the graph which showed the characteristic of the reduction gear of this embodiment, Comprising: (a) is a time domain, (b) is a graph which showed this characteristic in a frequency domain. FIG. 4 is a schematic view of another configuration example of the image carrier driving device and the speed reduction device provided in the image carrier driving device shown in FIG. ) Is a schematic front view. FIGS. 3A and 3B are schematic views illustrating a configuration example of a reduction gear including a pressure restricting unit having a configuration different from that in FIGS. 3 and 12, wherein (a) is a schematic side sectional view and (b) is a schematic front view. It is the schematic of another structural example regarding having provided the displacement means with respect to the image carrier drive device shown in FIG. 17, and the reduction gear provided in this, Comprising: (a) is a schematic sectional side view, (b) ) Is a schematic front view. FIG. 18 is a schematic view of another configuration example related to the cantilever mode of the drive shaft bearing with respect to the image carrier driving device shown in FIG. 17 and the speed reduction device provided therein; FIG. Side sectional view, (b) is a schematic front view. It is the schematic of another structural example regarding having provided the displacement means with respect to the image carrier drive device shown in FIG. 19, and the reduction gear provided in this, Comprising: (a) is a schematic sectional side view, (b) ) Is a schematic front view. FIG. 21 is a schematic view of another configuration example related to the fact that the displacing means includes an urging member with respect to the image carrier driving device and the speed reduction device provided in the image carrier driving device shown in FIG. FIG. 2B is a schematic front view. 20 is a schematic diagram of another configuration example related to the image carrier driving device shown in FIG. 20 and the speed reduction device provided therein, in which the displacement means does not include an elastic member but includes first and second urging members. (A) is a schematic sectional side view, and (b) is a schematic front view. It is the schematic for demonstrating the shift | offset | difference of the rotating shaft between a drive transmission member and a drive shaft, Comprising: (a) is a schematic front view, (b) And (c) is a schematic top view.

  FIG. 1 schematically shows an image forming apparatus to which the present invention is applied, which is a multicolor image forming apparatus capable of forming a color image. The image forming apparatus 100 is a combination machine of a color laser printer and a facsimile, but may be another type of image forming apparatus such as another type of printer, facsimile, copying machine, copying machine and printer combination machine, or the like. . The image forming apparatus 100 performs an image forming process based on an image signal corresponding to image information received from the outside. This is the same when the image forming apparatus 100 is used as a facsimile. The image forming apparatus 100 can form an image on a sheet-like recording medium using not only plain paper generally used for copying, but also OHP sheets, cardboard, cardboard, cardboard, and envelopes. It is.

  The image forming apparatus 100 is a cylindrical photosensitive member that is a latent image carrier as a plurality of image carriers that can form images as images corresponding to colors separated into yellow, magenta, cyan, and black. This is a tandem structure that adopts a tandem structure in which body drums 20Y, 20M, 20C, and 20BK are arranged in parallel, in other words, a tandem image forming apparatus.

  The photoconductive drums 20Y, 20M, 20C, and 20BK have the same diameter, and the outer peripheral surface of the transfer belt 11 as a transfer conveyance belt that is an endless belt disposed almost in the center of the main body 99 of the image forming apparatus 100. They are arranged at equal intervals on the side, that is, on the image forming surface side.

  The photosensitive drums 20Y, 20M, 20C, and 20BK are arranged in this order from the upstream side in the A1 direction that is the moving direction of the transfer belt 11. The photoconductive drums 20Y, 20M, 20C, and 20BK are image stations 60Y, 60M, 60C, and 60BK that are image forming units as image forming units for forming yellow, magenta, cyan, and black images, respectively. Is provided.

  The visible image, that is, the toner image formed on each of the photosensitive drums 20Y, 20M, 20C, and 20BK is superimposed and transferred onto a transfer sheet that is a transfer medium that is a recording medium conveyed by the transfer belt 11 that moves in the arrow A1 direction. It has come to be.

  In the superimposing transfer to the transfer belt 11, the toner images formed on the photosensitive drums 20Y, 20M, 20C, and 20BK are superimposed on the same position on the transfer paper in the process in which the transfer paper is moved in the A1 direction by the transfer belt 11. By applying voltage by transfer units 12Y, 12M, 12C, and 12BK as transfer chargers disposed at positions facing the respective photoconductive drums 20Y, 20M, 20C, and 20BK with the transfer belt 11 interposed therebetween. , The timing is shifted from the upstream side toward the downstream side in the A1 direction, and the transfer is performed at a transfer position that is opposite to each of the photosensitive drums 20Y, 20M, 20C, and 20BK and the transfer belt 11.

  The transfer belt 11 is an elastic belt whose entire layer is formed using an elastic member such as a rubber agent. The transfer belt 11 may be a single-layer elastic belt, may be an elastic belt using a part of the elastic belt, or a conventionally used fluorine-based resin, polycarbonate resin, or polyimide resin. Or an inelastic belt may be used.

  The image forming apparatus 100 is a transfer conveyance device that includes four image stations 60Y, 60M, 60C, and 60BK, and is disposed to face the photosensitive drums 20Y, 20M, 20C, and 20BK, and includes a transfer belt 11. And a transfer belt unit 10 as a certain belt unit.

  The image forming apparatus 100 is also transported from the sheet feeding device 61, a sheet feeding device 61 on which transfer paper transported between the photosensitive drums 20 </ b> Y, 20 </ b> M, 20 </ b> C, 20 </ b> BK and the transfer belt 11 is stacked. The recording sheet that has been fed toward the transfer portion between the photosensitive drums 20Y, 20M, 20C, and 20BK and the transfer belt 11 at a predetermined timing that matches the timing of toner image formation by the image stations 60Y, 60M, 60C, and 60BK. It has a registration roller pair 13 that feeds out, and a sensor (not shown) that detects that the leading edge of the transfer paper has reached the registration roller pair 13.

  The image forming apparatus 100 also includes a fixing device 6 as a roller fixing type fixing unit for fixing the toner image onto the transfer paper onto which the toner image has been transferred, and the transfer paper that has passed through the fixing device 6 outside the main body 99. A paper discharge roller 7 for discharging, a paper discharge tray 17 disposed on the side of the main body 99 and for stacking transfer paper discharged to the outside of the main body 99 by the paper discharge roller 7, and yellow, magenta, And a toner bottle (not shown) as a toner hopper filled with cyan and black toners.

  The image forming apparatus 100 also includes a CPU (not shown) and storage means such as a ROM and a RAM (not shown). As shown in FIG. 2, image forming such as drive control of the photosensitive drums 20Y, 20M, 20C, and 20BK is performed. Control means 40 for controlling the overall operation of the apparatus 100 is provided.

  As shown in FIG. 1, the transfer belt unit 10 includes a transfer inlet roller 72 that also serves as a driving roller as a driving member as a plurality of winding members around which the transfer belt 11 is wound in addition to the transfer belt 11. And a driven roller 73.

  The transfer belt unit 10 is also disposed opposite to the transfer belt 11 and is disposed opposite to the transfer belt 11 on the upstream side of the charge eliminator 74 in the A1 direction. A position shift detection sensor 75 configured to detect a pattern of each color formed on the transfer belt 11 in the position shift detection mode, and a transfer belt disposed opposite to the transfer belt 11 downstream of the static eliminator 74 in the A1 direction. 11 has a cleaning device 18 as a transfer belt cleaning device provided with a transfer cleaning brush (not shown) for cleaning the surface.

The transfer entrance roller 72 is rotationally driven by driving a motor as a drive source (not shown), and thereby the transfer belt 11 is rotationally driven in the A1 direction. The transfer entrance roller 72 is connected to a power source (not shown) and functions as a charging roller as a charging unit that charges the transfer belt 11 so that the transfer belt 11 electrostatically attracts the transfer paper.
The driven roller 73 functions as a tension roller that urges the transfer belt 11 so that the transfer belt 11 is rotationally driven with a constant tension.

  The static eliminator 74 neutralizes the charge on the surface of the transfer belt 11 charged by the transfer entrance roller 72 so that the pattern, other toner, paper dust, and the like on the transfer belt 11 are easily removed by the cleaning device 18.

  The position shift detection sensor 75 detects the pattern of each color formed on the transfer belt 11 by each of the image stations 60Y, 60M, 60C, and 60BK in the position shift detection mode, and respectively detects the image stations 60Y, 60M, 60C, and 60BK. The misalignment of the image forming position by each is read. Based on the read position deviation, the image forming positions by the image stations 60Y, 60M, 60C, and 60BK are adjusted by the control unit 40 so that the position deviation is eliminated. A reflection type photo sensor or a transmission type photo sensor is used as the positional deviation detection sensor 75.

The fixing device 6 includes a fixing roller 62 that is a heating roller having a heat source (not shown), and a pressure roller 63 that is pressed against the fixing roller 62, and adds a transfer sheet carrying a toner image to the fixing roller 62. By passing the toner image through a fixing portion that is a pressure contact portion with the pressure roller 63, the carried toner image is fixed on the surface of the transfer paper by the action of heat and pressure.
The sheet feeding device 61 includes a paper feed tray 15 that is a paper feed cassette on which transfer papers are stacked, and a paper feed roller 16 that feeds transfer papers stacked on the paper feed tray 15.

  Regarding the image stations 60Y, 60M, 60C, and 60BK, the configuration will be described as a representative of the configuration of the image station 60Y including the photosensitive drum 20Y. Since the configuration of the other image station is substantially the same, in the following description, for the sake of convenience, a reference numeral corresponding to the reference symbol assigned to the configuration of the image station 60Y is attached to the configuration of the other image station. Further, detailed description will be omitted as appropriate, and those with Y, M, C, and K at the end of the reference numerals are configurations for forming yellow, magenta, cyan, and black images, respectively. Will be shown.

  The image station 60Y including the photosensitive drum 20Y has a cleaning unit for cleaning the transfer device 12Y and the photosensitive drum 20Y around the photosensitive drum 20Y along a rotation direction B1 which is a clockwise direction in the drawing. A cleaning device 70Y, a charging device 30Y as a charging unit for charging the photosensitive drum 20Y to a high voltage, and a developing device 50Y as a developing unit for developing the photosensitive drum 20Y. is doing.

  The image station 60Y is also disposed above the photosensitive drum 20Y and serves as an optical writing device that is a writing unit that exposes the photosensitive drum 20Y at a position between the charging device 30Y and the developing device 50Y in the direction B1. It has an optical scanning device 8Y as a writing device. The optical scanning device 8Y scans and exposes the surface to be scanned formed by the surface of the photosensitive drum 20Y to form an electrostatic latent image, which is a laser beam as a laser beam based on an image signal. LY is emitted.

  As shown in FIG. 2, the image station 60Y also includes a motor 81Y as a drive source for rotationally driving the photosensitive drum 20Y, and an image carrier as a drive unit that rotationally drives the photosensitive drum 20Y by the driving force of the motor 81Y. A driving device 80Y is provided. Details of the image carrier driving device 80Y will be described later.

  With the configuration described above, the surface of the photosensitive drum 20Y is uniformly charged by the charging device 30Y as it rotates in the B1 direction, and corresponds to the yellow color by the exposure scanning of the beam LY from the optical scanning device 8. An electrostatic latent image is formed. The electrostatic latent image is formed by scanning the beam LY in the main scanning direction, which is a direction perpendicular to the paper surface, and performing sub scanning in the circumferential direction of the photosensitive drum 20Y by rotating the photosensitive drum 20Y in the B1 direction. This is done by scanning in the direction as well.

  To the electrostatic latent image formed in this manner, charged yellow toner supplied by the developing device 50Y adheres, and is developed into a yellow color to be visualized. The toner image, which is a visible image, is transferred to transfer paper that moves in the A1 direction by the transfer device 12Y, and foreign matters such as toner remaining after transfer are scraped off and stored by the cleaning device 70Y, and the photosensitive drum 20Y is charged. It is used for the next charging by the device 30Y.

  Similarly, toner images of the respective colors are formed on the other photosensitive drums 20C, 20M, and 20BK, and the formed toner images of the respective colors are the same on the transfer paper that moves in the A1 direction by the transfer units 12C, 12M, and 12BK. Sequentially transferred to the position.

  The transfer paper conveyed between the photosensitive drums 20Y, 20C, 20M, and 20BK and the transfer belt 11 is fed from the sheet feeding device 61, and is sensitized by the registration roller pair 13 based on the detection signal from the sensor. The toner image on the body drum 20 </ b> Y is sent out at a timing when the leading end of the toner image faces the transfer belt 11.

  When the toner images of all colors are sequentially transferred and carried on the transfer paper, the transfer paper peels off from the transfer belt 11 and enters the fixing device 6, and passes through the fixing portion between the fixing roller 62 and the pressure roller 63. The carried toner image is fixed by the action of heat and pressure, and a color image as a composite color image is formed on the transfer paper by this fixing process. The fixed transfer paper that has passed through the fixing device 6 passes through the paper discharge roller 7 and is stacked on the paper discharge tray 17. On the other hand, the transfer belt 11 that has finished transporting the transfer paper is discharged by the charge eliminator 74 and then cleaned by the cleaning device 18 to prepare for the transfer of the next transfer paper.

  In the image forming apparatus 100, the image carrier driving devices 80Y, 80M, 80C, and 80BK have substantially the same configuration. Hereinafter, the image carrier driving devices 80Y, 80M, 80C, and 80BK will be described as the image carrier driving device 80. Accordingly, the photosensitive drums 20Y, 20M, 20C, and 20BK will be described as the photosensitive drum 20, and the motors 81Y, 81M, 81C, and 81BK will be described as the motor 81.

  As shown in FIG. 3, the image carrier driving device 80 reduces the rotational speed of the motor 81 and the motor 81 to the rotational speed required for the rotation of the photosensitive drum 20 and transmits it to the photosensitive drum 20 to transmit it to the photosensitive drum 20. And a coupling 83 that connects the speed reduction device 82 and the photosensitive drum 20.

  The motor 81 has a motor shaft 81a that is an output shaft thereof, and a drive shaft 86 that is coupled to the tip of the motor shaft 81a via a flexible joint 110 as a coupling. The drive shaft 86 is positioned on the rotation center axis of the output of the motor 81 and is rotationally driven by the motor 81. The output shaft of the motor 81 is substantially provided as a transmission shaft that transmits the driving force of the motor 81 in other words. The motor shaft 81a itself may be used. The flexible joint 110 is an integral joint that transmits rotational driving force while absorbing the eccentricity and declination between the motor shaft 81a and the drive shaft 86, and is slidable in the Oldham type, disk type, universal joint type or axial direction. The universal joint type.

  The coupling 83 is disposed at the end of the shaft 21 having the rotation center of the photosensitive drum 20 as the rotation center and at the end of the output shaft 84 of the reduction gear 82, and is coupled to the coupling 83a. A coupling 83b that meshes with the coupling 83b. The coupling 83 can be separated by detaching the coupling 83a and the coupling 83b. The coupling 83a and the coupling 83b are fitted with no play in the engaged state, and the shaft 21 and the output shaft 84 are located on the same axis. Therefore, a decrease in rotational accuracy of the photosensitive drum 20 in the coupling 83 is ignored. It is possible.

  Here, if the speed reduction device 82 uses a gear to decelerate the rotation of the motor 81, the rotational speed of the photosensitive drum 20 may fluctuate due to backlash as described above. If the rotational speed of the photosensitive drum 20 varies, there is a problem because image quality is degraded due to image misalignment or streaks due to density unevenness. Since this problem is conspicuous as color misregistration in a configuration in which toner images of respective colors are superimposed to obtain an image as in the image forming apparatus 100, the rotational speed of the photosensitive drum 20 needs to be performed with high accuracy. Further, if the speed reducing device 82 uses a planetary roller to decelerate the rotation of the motor 81, it is difficult to reduce the size and cost as described above.

  Therefore, the speed reduction device 82 is driven and fixed around the output shaft 84 so as to drive the photosensitive drum 20 accurately and smoothly and to be a relatively small and low-cost mechanism. The wheel 85 is a rotation transmission wheel as a drive transmission member which is provided at the center, in other words, coaxially with the photosensitive drum 20 and is in contact with the drive shaft 86, and has a rotation radius larger than the rotation radius of the drive shaft 86. The wheel 85 which has is provided. The reduction gear 82 uses the friction between the drive shaft 86 and the wheel 85 without using gears and planetary rollers by rotating the wheel 85 so as to rotate integrally with the photosensitive drum 20 by the drive shaft 86. To decelerate. The drive shaft 86 and the wheel 85 form a columnar shape with at least the abutting portion as the center of rotation, and are in contact with each other on the circumferential surfaces 86a and 85a of the columnar portion. In this method, since drive transmission is performed between smooth circumferential surfaces, rotation unevenness caused by drive transmission by a gear such as backlash is suppressed. In addition, it is easier to finish the surface of the circumferential surface with higher accuracy than gear processing, and because roundness and the like can easily obtain an accuracy one digit higher than that of the gear, drive transmission is performed extremely accurately and smoothly. There are advantages.

  However, in order to transmit the drive by friction between the circumferential surfaces 86a and 85a, the circumferential surfaces 86a and 85a must be in a pressure-contact state, but simply by adjusting the arrangement positions of the drive shaft 86 and the wheel 85. Assuming that the circumferential surfaces 86a and 85a are in pressure contact with each other, it is difficult to perform drive transmission while suppressing fluctuations in the rotational speed of the drive shaft 86 and the wheel 85 as described above.

  Therefore, the speed reduction device 82 includes a pressing restriction means 88 as a pressure contact restriction means for pressing the drive shaft 86 toward the rotation center of the wheel 85. The pressing restricting means 88 has various configuration examples as will be described later. In order to regulate the displacement of the drive shaft 86 in the rotation direction of the wheel 85 in common with each configuration example, the drive shaft A regulating member is provided that engages with 86 in a predetermined manner and presses the drive shaft 86 against the circumferential surface 85a. The regulating member in the configuration example shown in FIG. 3 includes two pressure rollers 87 a as driven members that abut on the drive shaft 86 and rotate following the drive shaft 86.

  In addition to the output shaft 84 and the wheel 85, the speed reduction device 82 includes a wheel 89 and a housing 89 that supports the motor 81, and a bearing 90 that rotatably supports the output shaft 84 with respect to the housing 89. The housing 89 is fixedly supported by the output shaft 84 and has the rotation center of the output shaft 84 as the rotation center. In other words, the encoder disk 91 provided coaxially with the output shaft 84 and the periphery of the encoder disk 91 are received. It has an encoder sensor 92 as a rotational speed detecting means which is fixedly supported on the inner surface of the housing 89 and detects the rotational speed of the output shaft 84, in other words, the rotational speed.

  The speed reduction device 82 also includes an oil storage member 93 having a recess 93a positioned below the housing 89 and receiving the periphery of the wheel 85, and a circumferential surface 85a of the wheel 85 stored in the recess 93a and entering the recess 93a. Oil 94 as a lubricant whose periphery is immersed, and a motor control circuit 41 for controlling the rotation speed, timing, and the like of the motor 81 based on the output of the encoder sensor 92 are provided.

  The drive shaft 86 is a shaft-like member made of metal and subjected to quenching and tempering heat treatment, and is connected to the motor shaft 81 a via the flexible joint 110. It is preferable to use a needle roller generally used for a needle roller bearing as the drive shaft 86 because both heat treatment and dimensional accuracy are stable. When the drive shaft 86 is constituted by the motor shaft 81a itself, the drive shaft 86 is formed by heat-treating the tip of the motor shaft 81a to a required size.

  The wheel 85 is a disk-shaped member made of metal and subjected to quenching and tempering heat treatment, and is fixed to the output shaft 84 by press-fitting. The fixing mode of the wheel 85 with respect to the output shaft 84 may be another mode. Since it is important for the wheel 85 to have the circumferential surface 85a located on the same axis as the output shaft 84, cutting is performed after fixing the wheel 85 to the output shaft 84, thereby obtaining the necessary accuracy. As a metal material used as the material of the wheel 85, a material such as SUJ2 used for a rolling bearing is preferable in terms of hardness and wear resistance.

  The housing 89 has a part of the side plate 89a of the main body 99 and a drive side plate 89b fixed to the side plate 89a. The side plate 89 a and the driving side plate 89 b are non-moving bodies that do not move with respect to the main body 99, and the housing 89 is also a non-moving body that does not move with respect to the main body 99. The motor 81 is fixedly supported on the driving side plate 89b.

  The bearing 90 is disposed on each of the side plate 89a and the drive side plate 89b, and supports the output shaft 84 in two places so as to be freely rotatable. The coupling 83b is fixed to the output shaft 84 outside the housing 89 on the side plate 89a side.

The encoder disk 91 is located between the side plate 89 a and the wheel 85 of the output shaft 84. The encoder disk 91 is provided with a large number of radial slits.
The encoder sensor 92 is fixed on the inner surface of the side plate 89a. The encoder sensor 92 detects the number of rotations of the output shaft 84 by detecting the slit of the encoder disk 91.

  The motor control circuit 41 keeps the rotational speed of the photosensitive drum 20 constant, so that the rotational speed of the drive shaft 86 is kept constant based on the rotational speed of the output shaft 84 detected by the encoder sensor 92. It functions as a rotation speed control means for feedback control of the motor, and is realized as one function of the control means 40.

  Such feedback control is performed because the photosensitive drum 20 is driven by friction between the drive shaft 86 and the wheel 85. That is, in friction transmission, even if the rotational speed of the motor 81 is kept constant, the rotational speed of the photosensitive drum 20 is affected by the processing accuracy and wear of the diameter of the wheel 85, and by the influence of minute slipping. This is not necessarily the same as the number, and is performed because a deviation may occur.

Such feedback control is performed according to the configuration of the block diagram shown in FIG.
First, when the target value of the rotational speed of the photosensitive drum 20 for forming an appropriate image on the photosensitive drum 20 is set in the motor control circuit 41, the controller 42 of the motor control circuit 41 based on the target value. A drive signal is generated, the driver 43 of the motor 81 is driven by this signal, and the motor 81 is driven by energization from the driver 43. The number of revolutions of the motor 81 is reduced by the ratio of the radius of rotation of the drive shaft 86 and the wheel 85, that is, a so-called reduction ratio, and transmitted to the output shaft 84. The rotational speed of the output shaft 84 is detected by a pulse period generated by an encoder sensor 92 (shown as “encoder” in FIG. 4) by detecting a slit of an encoder disk 91 provided coaxially with the output shaft 84. . This pulse period is input to the motor control circuit 41, and a drive signal is generated toward the driver 43 by the controller 42 so that the pulse period becomes constant.

  In this way, the pulse output of the encoder sensor 92 is input to the motor control circuit 41, and the drive shaft 86 is controlled by controlling the rotation speed of the motor 81 so that the rotation speed of the photosensitive drum 20 becomes a target constant value. Even if the diameter and shape of the peripheral surface 86a and the peripheral surface 85a of the wheel 85 vary depending on the processing accuracy, wear, and the like, the rotational speed of the photosensitive drum 20 is kept accurately constant.

  The pressing restricting means 88 includes, in addition to the pressure rollers 87a and 87a, a pressure arm 95 as a bracket that is a support member that supports the pressure rollers 87a and 87a, and a pressure arm fulcrum that slidably supports the pressure arm 95 on the drive side plate 89b. The shaft 96 and one end of the shaft 96 abut against the pressure contact arm 95, and the pressure contact rollers 87a and 87a press the drive shaft 86. The pressure contact arm 95 is urged to the center of the shaft 96 and the drive shaft 86 is pressed against the circumferential surface 85a. A spring 97 that is a pressure contact spring as a pressing member (pressure member) to be pressed and a screw 98 for positioning the spring 97 are provided. The shaft 96 is a press swinging fulcrum member that serves as a swinging fulcrum of the pressing restricting means 88 for pressing the drive shaft 86.

  Each of the pressure rollers 87a and 87a has a shaft 87a1 supported by a pressure arm 95 which is made of metal and has been subjected to quenching and tempering heat treatment, and is rotatably supported by the shaft 87a1. The pressure-contact rollers 87a and 87a can each be constituted by a normal ball bearing or a needle-shaped roller bearing.

  The pressure contact rollers 87 a and 87 a are in contact with the drive shaft 86 so that the drive shaft 86 is sandwiched between peripheral surfaces parallel to the rotation center of the drive shaft 86. The contact points between the pressure contact rollers 87a and 87a and the drive shaft 86 are two locations on the peripheral surface of the drive shaft 86 opposite to the peripheral surface facing the wheel 85. As a result, the drive shaft 86 is held in position by a total of three contact points including the contact points with the wheel 85, and displacement of the drive shaft 86 is prevented.

  Further, the position of the contact point with the pressure contact rollers 87a and 87a is such that the resultant force of the pressure contact rollers 87a and 87a pressing the drive shaft 86 toward the circumferential surface 85a at this contact point is determined by the drive shaft 86 being the center of rotation of the wheel 85. The position is symmetrical with respect to a straight line connecting the rotation center of the drive shaft 86 and the rotation center of the wheel 85 so as to be directed in the direction toward. As a result, the force that moves the drive shaft 86 in the direction intersecting the straight line is canceled out by the pressing force generated by the contact points with the pressure rollers 87a and 87a, and the drive shaft 86 is positioned with higher accuracy and driven. The shaft 86 is pressed straight against the wheel 85.

  The screw 98 is supported by the drive side plate 89b by abutting the other end of the spring 97 on one end and screwing the end of the screw 98 on the drive side plate 89b functioning as a fixed bracket. Therefore, by adjusting the screwing position of the screw 98 with respect to the drive side plate 89b, the urging force of the press contact arm 95 by the spring 97 is adjusted, thereby adjusting the pressing force of the press contact rollers 87a and 87a by the spring 97 with respect to the drive shaft 86. Then, the pressure contact force between the drive shaft 86 and the wheel 85 is adjusted, and the frictional force between them is adjusted.

  Here, if the parallelism between the rotation axis (axis center) of the drive shaft 86 and the rotation axis (axis center) of the wheel 85 is not maintained, a skew angle is generated, and a thrust force is generated on each axis as the rotation is driven. End up.

  FIG. 23 is a schematic view of a contact portion between the drive shaft 86 and the wheel 85. FIG. 23A is a schematic front view of the contact portion, FIG. 23B is a schematic top view of the contact portion when the parallelism of both rotation axes is maintained, and FIG. It is a schematic top view of the contact part when the parallelism of is not maintained. In FIG. 23A, the drive shaft 86 is rotated in the direction of the arrow C2 by the rotational driving force of the motor 81. On the other hand, the wheel 85 is rotated in the direction of the arrow B <b> 2 by the rotation transmission from the drive shaft 86. At this time, the rotational driving force T acts on the wheel 85 at the contact portion with the drive shaft 86. On the other hand, a reaction force R of the rotational driving force T of the wheel 85 acts on the drive shaft 86. Even if the reaction force R acts on the drive shaft 86, the drive shaft 86 is pressed against the wheel 85 by the press contact arm 95 via the two press contact rollers 87a so that the drive shaft 86 does not move. In FIG. 23B, the parallelism is maintained between the rotating shaft of the drive shaft 86 and the rotating shaft of the wheel 85, so that the rotational driving force T has a direction of action that coincides with the rotating direction of the wheel 85 and is smooth. The rotational driving force is transmitted. Since the two pressing rollers 87a are supported adjacent to each other by the pressing arm 95 that is the same member, the accuracy of the parallelism between these pressing rollers 87a is high. Further, since the drive shaft 86 is supported by being sandwiched between the two pressure rollers 87a, the accuracy of the parallelism with the pressure roller 87a is high. Therefore, as shown in FIG. 23C, a state in which the pressure contact roller 87a and the drive shaft 86 are not maintained in parallel with the wheel 85 is likely to occur. In the illustrated example, if the rotation axis of the drive shaft 86 and the rotation axis of the wheel 85 are eccentric with a skew angle θ, the wheel 85 has a rotational axis direction (right direction in the figure) as a component of the rotational drive force T. A thrust force Ts (= Tsinθ) acts on the drive shaft 86, and a thrust force Rs (= Rsinθ) acts on the drive shaft 86 as a component of the reaction force R in the rotation axis direction (left direction in the figure). The thrust force Rs acting in the direction of the rotational axis of the drive shaft 86 also acts on the pressure contact roller 87a and the pressure contact arm 95 that supports the pressure contact roller 87a. These thrust forces Ts and Rs not only cause drive transmission loss, but also cause movement of each rotating body in the axial direction, causing heat generation and damage due to contact, and possibly reducing the life of the reduction gear 82.

  Therefore, the speed reduction device 82 is configured such that the pressing restricting means 88 can swing the pressure contact arm 95 using the thrust force Rs generated on the drive shaft 86, and each rotation shaft and wheel of the pressure contact roller 87 a and the drive shaft 86. The parallelism with the 85 rotation axis can be automatically corrected.

  As shown in FIG. 3 (b), the speed reducing device 82 of the present embodiment is configured so that the pressure restricting means 88 swings so that the parallelism of the rotation axes is automatically adjusted. A shaft adjustment swing fulcrum portion 111 having a swing fulcrum and a shaft adjustment swing guide portion 120 that guides the swing of the pressing restricting means 88 are provided. The shaft adjustment swinging fulcrum 111 is provided with a spring 97 as a pressure member for pressing the drive shaft 86 toward the rotation center of the wheel 85. Further, the shaft adjustment swing guide portion 120 can rotate the shaft 96 as a press swing support member serving as a press swing support point of the press restricting means 88 for pressing the drive shaft 86, and the shaft 96. A shaft support bracket 112 as a support member to be supported is provided. As described above, the pressure contact arm 95 is swingable in the vertical direction in the figure with the shaft 96 as a fulcrum and the left side in the figure biased by the spring 97. Further, a long hole 112 a extending in the longitudinal direction of the press contact arm 95 is formed as a support hole of the shaft support bracket 112 engaged so that the shaft 96 penetrates. By moving the shaft 96 in the longitudinal direction of the long hole 112a, the right side of the pressure contact arm 95 in the drawing is also swung toward the front side and the back side with respect to the paper surface, using the screw 98 as a pivot for pivot adjustment. It is possible to move.

  FIG. 5 is a schematic top view of the vicinity of the contact portion between the drive shaft 86 and the wheel 85. FIG. 5A shows a pressure contact roller 87a, a skew angle between the rotation shaft of the drive shaft 86 and the rotation shaft of the wheel 85, and a pressure contact arm. 95 is a schematic top view of the state in which the lower side inclines to the left side, (b) is a schematic top view in which the pressing arm 95 swings and the parallelism is automatically corrected, and (c) is a drawing of the pressing arm 95. It is a schematic top view in the state where the middle lower side is inclined to the right side.

  In FIG. 5A, a screw 98 is provided in a screw through hole 95b formed in the press contact arm 95, and the press contact arm 95 swings with the central axis of the screw 98 as a swing fulcrum 98a. Since the pressure contact roller 87 a is supported by the pressure contact arm 95, it swings integrally with the pressure contact arm 95. Further, since one end portion of the drive shaft 86 is cantilevered by the flexible joint 110, when the wheel 85 is pressed by the two pressing rollers 87a, the drive shaft 86 is inclined by the rotation of the rotation shaft. Following this, both the pressure roller 87a and the pressure arm 95 swing. Since the drive shaft 86, the pressure contact roller 87a, and the pressure contact arm 95 integrally swing like a caster around the swing support point 98a, the swing support point 98a reacts with the reaction force R acting on the drive shaft 86 when the drive shaft 86 rotates. Is provided at a position away from the installation position of the drive shaft 86 in the direction of the reaction force R. Further, the press contact arm 95 is supported by a pair of shaft support brackets 112 by a shaft 96 disposed on the opposite side (lower side in the figure) to the swing fulcrum 98a. The interval (span) of the shaft support bracket 112 is set so as not to contact within the swing range of the press contact arm 95. In the illustrated example, the rotation axis of the drive shaft 86 is tilted obliquely upward to the left with respect to the rotation axis of the wheel 85 to generate a skew angle, and the reaction force R and the thrust force Rs act on the drive shaft 86 by the rotation drive. . The thrust force Rs acts as a force that moves the drive shaft 86 in the right direction in the figure, and the drive shaft 86, the pressure contact roller 87a, and the pressure contact arm 95 swing in the direction of the arrow Yr. Along with this swinging, the skew angle between the rotating shaft of the drive shaft 86 and the rotating shaft of the wheel 85 decreases, and the thrust force Rs also decreases. When the skew angle becomes zero, the thrust force Rs also becomes zero and the oscillation stops. Then, as shown in FIG. 5B, the rotational drive is performed in a state where the parallelism without a skew angle between the rotation shaft of the drive shaft 86 and the rotation shaft of the wheel 85 is automatically corrected to a good state. Do.

  Further, in FIG. 5 (c), in contrast to the state of FIG. 5 (a), the rotation shaft of the drive shaft 86 is inclined obliquely upward to the right with respect to the rotation shaft of the wheel 85, and a skew angle is generated. A reaction force R and a thrust force Rs act on the drive shaft 86. The thrust force Rs acts as a force that moves the drive shaft 86 in the left direction in the drawing, and the drive shaft 86, the pressure contact roller 87a, and the pressure contact arm 95 swing in the direction of the arrow Yl. Thus, in the same manner as the above-described operation, as shown in FIG. 5B, the parallelism without a skew angle between the rotating shaft of the drive shaft 86 and the rotating shaft of the wheel 85 is automatically improved. Rotation drive is performed in a state corrected to.

  FIG. 6 shows a configuration example of another speed reducer in which the configuration of the mounting portion of the motor 81 is different from that in FIG. In this configuration example, a configuration in which the motor 81 is attached to the pressure contact arm 95 is used instead of the configuration in which the motor 81 is attached to the drive side plate 89b. In the same figure, the part which attached | subjected the code | symbol is the structure similar to said structure, and abbreviate | omits description.

  In FIG. 6, the press contact arm 95 is configured to have a shape to which the motor 81 can be attached, and the motor 81 is directly attached. In this configuration, the press contact arm 95 swings around the swing fulcrum 98a integrally with the motor 81, the drive shaft 86, and the press contact roller 87a. The drive shaft 86 may be fixed to the motor shaft 81a, or the motor shaft 81a may be formed as the drive shaft 86. Since the flexible joint 110 is not provided, the number of components can be reduced, which is advantageous for cost reduction.

  FIG. 7 is a schematic top view of the vicinity of the contact portion between the drive shaft 86 and the wheel 85 in the reduction gear configured as shown in FIG. 6, and (a) shows the rotation of the wheel 85 and the rotary shaft of the pressure contact roller 87 a and the drive shaft 86. A schematic top view of a state in which a skew angle is generated in the shaft and the lower side of the press contact arm 95 in the drawing is inclined to the left side, and (b) is a schematic top view in which the press contact arm 95 swings and the parallelism is automatically corrected. (C) is a schematic top view of a state in which the lower side of the press-contact arm 95 is inclined to the right side.

In FIG. 7A, the thrust arm Rs acting to the right in the drawing with respect to the drive shaft 86 by rotational driving causes the press contact arm 95 to be integrated with the motor 81, the drive shaft 86, and the press contact roller 87a. Swing in the direction of the arrow Yr around 98a, and as shown in FIG. 7B, the parallelism without a skew angle between the rotating shaft of the drive shaft 86 and the rotating shaft of the wheel 85 is automatically in a good state. Rotation drive is performed in a state corrected to.
In FIG. 7 (c), the thrust arm Rs acting on the drive shaft 86 in the left direction in the figure by rotational drive causes the press contact arm 95 to swing together with the motor 81, the drive shaft 86, and the press contact roller 87a. Swing in the direction of the arrow Yl around the moving fulcrum 98a, as shown in FIG. 7B, the parallelism with no skew angle between the rotating shaft of the drive shaft 86 and the rotating shaft of the wheel 85 is in a good state. Rotation drive is performed in a state where it is automatically corrected.

FIG. 8 shows another configuration example of the pressing restricting means 88 configured to be swingable. In this configuration example, the shaft support bracket 112 is replaced with a configuration that uses a member that is not easily deformed, and a configuration using a flat plate member having flexibility. This configuration is advantageous for simplification of the apparatus and low cost. The flat shaft support bracket 112 can be made of a metal material such as SPCC steel plate, phosphor bronze, or SUS304-CSP used as a leaf spring material. Further, the flexible part 112b may be formed by making the plate thickness of the part to be deformed thinner than other parts (see FIG. 8C).
In the schematic front view of FIG. 8A, the shaft 96 of the press contact arm 25 is supported by a pair of flat shaft support brackets 112, and supports the pressurizing force of the press contact spring 97. The flat shaft support bracket 112 allows deformation in the direction of arrow F as shown in the schematic top view of FIG. 8B, and press-contact as shown in the schematic side view of FIG. The arm 95 can be swung by the deformation of the shaft support bracket 112. The shaft 96, the shaft support bracket 112, and the long hole 112a constitute the shaft adjustment swing guide portion 120.

  FIG. 9 shows still another configuration example of the pressing restricting means 88 configured to be swingable. In this configuration example, instead of the configuration using the shaft 95 that supports the press-contact arm 95, the configuration is supported using a rotating roller. The press contact arm 95 supports the pressing force of the press contact spring 97 by two rollers 114 rotatably supported by a flange 113 on the upper surface of the end opposite to the end where the screw 98 is provided. Is supported in the direction of the arrow Y around the swing fulcrum 98a. By using the roller 114, the press contact arm 95 can swing more smoothly, swing in response to a smaller thrust force Rs, and the rotation axis of the drive shaft 86 and the rotation axis of the wheel 85 are more accurately parallelized. Can be realized. The number of rollers 114 can be arbitrarily set from the pressure resistance of each roller in the pressing direction. The flange 113 and the roller 114 constitute an axis adjustment swing guide portion 120.

Although the example of FIG. 9 uses a spherical roller as the roller 114, a cylindrical roller can also be used.
FIG. 10 shows a configuration using a cylindrical roller instead of the configuration using a spherical roller as the roller 114. In the schematic front view of FIG. 10A, a cylindrical roller 114 b is disposed on the flange 114 as the roller 114. Since the cylindrical roller 114b is in line contact with the press contact arm 95, the pressure resistance is higher than that of the spherical roller. Further, as shown in the schematic top view of FIG. 10B, it is advantageous to reduce the sliding resistance if the rotating shaft of the cylindrical roller 114 is disposed toward the swing fulcrum 98a.

FIG. 11 shows still another configuration example of the pressing restricting means 88 configured to be swingable. In this rocking means, instead of the configuration in which the screw 98 is a rocking fulcrum, the right side in the drawing of the press contact arm 95 is a rocking fulcrum. This configuration is advantageous when the wheel 85 is rotated in the direction of arrow B1.
In the schematic front view of FIG. 11A, the front end of the flange 113 is provided with a hemispherical convex portion 113a, and the press-contact arm 95 is formed with a concave portion 95c that can be slidably fitted with the convex portion 113a. The pressing force of the spring 97 is supported. Further, in the schematic top view of FIG. 11B, since the press-contact arm 95 has a through hole of the screw 98 formed by a long hole 95d, the foremost portion of the convex portion 113a of the flange 113 is used as a swing fulcrum 113b. The screw 98 side (upper side in the figure) can swing in the arrow Y direction. The screw 98 and the long hole 95d constitute an axis adjustment swing guide portion 121. In order to obtain good sliding between the convex portion 113a of the flange 113 and the concave portion 95c of the pressure contact arm 95, it is desirable that these materials have a low coefficient of friction and have excellent wear resistance. . Specifically, it is preferable to use a resin material based on polyacetal, nylon, Teflon (registered trademark), or a metal material such as oil-containing sintering. Also, a recess is formed in the flange 113. A configuration in which a hemispherical convex portion is formed on the pressure contact arm 95 may be employed.

  FIG. 12 shows still another configuration example of the pressing restricting means 88 configured to be swingable. In this pressing restricting means 88, a support member 87b that supports the drive shaft 86 is used as the restricting member instead of the press contact rollers 87a and 87a. In the same figure, the part which attached | subjected the code | symbol is the structure similar to said structure, and abbreviate | omits description.

  The support member 87b is a side on which the drive shaft 86 abuts on the wheel 85 so that a contact point with the drive shaft 86 occurs at least on the peripheral surface of the drive shaft 86 opposite to the peripheral surface facing the wheel 85. Is a member that supports the drive shaft 86 so as to contact the wheel 85 by contacting and supporting the drive shaft 86 from the opposite side, and accepts the drive shaft 86 to support the drive shaft 86 in a positioned state. It has the fitting part 87b1 which is a hollow to fit.

  The support member 87 b also functions as a pressurizing member that pressurizes the drive shaft 86 against the wheel 85 by the pressing force of the spring 97. The support member 87b slides at the fitting portion 87b1 with respect to the rotation of the drive shaft 86. Therefore, the material of the support member 87b is preferably a resin or metal bearing material. Specifically, it is preferable to use a resin material based on polyacetal, nylon, Teflon (registered trademark), or a metal material such as oil-containing sintering. Note that it is important that the drive shaft 86 is firmly fixed so that the drive shaft 86 does not move in the tangential direction of the peripheral surface 85a at the contact point with the wheel 85 even if the support member 87b is worn. .

FIG. 13 shows various specific shapes of the fitting portion 87b1.
FIG. 13A shows the shape of the support member 87b in which the fitting portion 87b1 is formed in the support member 87b as a U-shaped groove. In this shape, the contact point with the drive shaft 86 is a surface. Since it is a contact surface and can be taken relatively wide, it is advantageous for wear.
FIG. 13B shows the shape of the support member 87b in which the fitting portion 87b1 is formed in the support member 87b as a V-shaped groove, and the contact point with the drive shaft 86 is shown in FIG. Although less than the example, it is advantageous in that the position of the drive shaft 86 is firmly fixed even when worn.
FIG. 13C shows the shape of the support member 87b formed on the support member 87b as a fitting base 87b1 having a polygonal shape, specifically, a home base-like groove. Since there are more contacts than the example shown in FIG. 5B, the contact pressure of the surface at each contact is dispersed, which is advantageous for wear.

  In each of the press contact means 88 described above, the number of contact points between the regulating member and the drive shaft 86 is not limited to two as shown in FIG. 3, but is set to three or more as shown in FIG. 13 (c). Alternatively, as shown in FIG. 13 (a), three or more points may be formed by forming such contacts on a surface. Further, as in the example shown in FIG. 13, it is desirable that the contact point be symmetric with respect to a straight line connecting the rotation center of the drive shaft 86 and the rotation center of the wheel 85.

  The oil storage member 93 functions as a lubricating means for lubricating the oil 94 between the drive shaft 86 and the wheel 85 and between the drive shaft 86 and the pressure roller 87a or the support member 87b. The drive shaft 86, the wheel 85, the pressure contact roller 87a, and the support member 87b are formed of a metal material or the like subjected to heat treatment such as quenching as described above in order to obtain high rigidity, high durability, and smooth rotation transmission. Has been. Therefore, since a lubricant is required between these members, the oil 94 is stored in the oil storage member 93, the wheel 85 is constantly immersed in the oil, and the rotation of the wheel 85 causes the oil 94 to pass through the wheel 85. The oil 94 is supplied to the contact between the drive shaft 86 and the pressure roller 87a or the support member 87b through the drive shaft 86 by the rotation of the drive shaft 86.

  As the oil 94, general industrial oil may be used, but in this embodiment, a known traction oil known as a friction transmission driving oil is used. Traction oil is a lubricant that tends to vitrify under extreme pressure conditions, and maintains a coefficient of friction of about 0.1 under extreme pressure. Therefore, the traction oil is excellent in increasing the slip start torque, and is suitable for drive transmission by friction between the drive shaft 86 and the wheel 85, that is, drive transmission by rolling friction. When traction oil is used, the friction coefficient at high pressure is increased by 50% compared to the friction coefficient when using normal oil, and the transmittable torque is also increased by 50%.

  Here, the relationship between the transmission torque and the pressure contact force will be described. When a wheel 85 having a diameter of 60 mm is used to transmit torque of 1 N · m (about 10 kg · cm), the drive shaft 86 and the wheel 85 In the pressure contact portion, a frictional force of 1 / 0.03 = 33.3N is required. Since the frictional force is the product of the applied pressure and the friction coefficient μ, the applied pressure when traction oil is used as the oil 94 can be transmitted at 33.3 / 0.1 = 333 N (about 33.3 kg) or more. Become.

  A reduction ratio in the reduction gear 82 having such a configuration will be described. The shaft diameter of the drive shaft 86 is sufficient to drive the wheel 85 with a diameter of about 1 mm if the torque is small. When the shaft diameter of the drive shaft 86 is 1 mm, if the speed reduction ratio is 1/20, the diameter of the wheel 85 is 20 mm, and the speed reduction device 82 is very small. Even if the shaft diameter of the drive shaft 86 is 4 mm, the diameter of the wheel 85 when the reduction ratio is 1/20 is within 80 mm, and the mutual interval between the photosensitive drums 20 is about 100 mm. A sufficient space for arranging the speed reduction device 82 with respect to the photosensitive drum 20 is secured. Regarding the mutual interval between the photoconductive drums 20, the normal diameter of the photoconductive drums 20 is 30 mm to 60 mm, and it is considered that each of the photoconductive drums 20 is provided with the developing unit and the cleaning unit as described above. Such a mutual interval is generally 70 mm to 100 mm. Therefore, it can be seen that even when the shaft diameter of the drive shaft 86 is 4 mm, a sufficient space for disposing the speed reduction device 82 with respect to each photosensitive drum 20 is ensured.

The operation of the image carrier driving apparatus 80 configured as described above will be briefly described.
When the motor 81 as a drive source is driven, the drive shaft 86 rotates. The drive shaft 86 is pressed against the wheel 85 by the pressing restricting means 88 in a state where the displacement of the wheel 85 in the circumferential direction and the rotational direction is restricted, and the wheel 85 is swung by the swinging means of the pressing restricting means 88. A rotational driving force is transmitted to the wheel 85 while maintaining parallelism with the rotation axis. The wheel 85 is rotated by the rotational driving force, and the output shaft 84 that is rotatably supported by the bearings 90 and 90 is rotated, whereby the shaft 21 is rotated via the coupling 83, and the photosensitive drum 20 is rotated. Rotate. Further, the wheel 85 has a circumferential surface 85 a which is a drive transmission surface lubricated by the oil 94 stored in the oil storage member 93. The rotation of the output shaft 84 is detected by reading the rotation of the encoder disk 91 provided on the output shaft 84 by the encoder sensor 92, and the motor control circuit 41 cancels the rotation variation of the output shaft 84 detected by the encoder sensor 92. Thus, feedback control for driving the motor 81 is performed.

  In the reduction gear 82, since no gear is used, backlash caused by the gear is prevented, and friction between the drive shaft 86 and the wheel 85 is ensured by the pressing restricting means 88. It is not necessary to press each other by position adjustment with 85 itself, and these rotational fluctuations are suppressed, so that drive transmission without rotational unevenness is performed. Further, although the pressing restricting means 88 is provided, the planetary roller mechanism is not used, so that the apparatus can be miniaturized.

14 and 15, the state of occurrence of uneven rotation of the photosensitive drum 20 is compared between the case where the reduction gear using the gear is used and the case where the reduction gear 82 of the present embodiment is used.
FIG. 14 is a case where a reduction gear using a gear is used, and shows the occurrence of rotation unevenness in the case of one-stage reduction, where FIG. FIG. 2B shows a frequency analysis of the rotation unevenness. FIG. 15 shows the state of occurrence of uneven rotation when the speed reducer 82 is used. FIG. 15A shows the fluctuation of the rotation speed on the time axis, and FIG. 15B shows the rotation unevenness. This is a frequency analysis diagram.

In the case of gear reduction, vibration for each tooth is generated from FIG. 14A, and from FIG. 14B, in frequency analysis, C: one rotation cycle of the photosensitive shaft, D: one rotation cycle of the motor shaft, E: It turns out that the rotation nonuniformity of the one-tooth period of a gearwheel and the fluctuation | variation in the higher order frequency generate | occur | produce.
On the other hand, when the speed reducer 82 is used, the rotation unevenness of the one-tooth period of the gear, that is, the rotation fluctuation of the tooth pitch, which has appeared as E in FIG. Further, from FIG. 15B, it can be seen that the rotation unevenness of C: one rotation cycle of the photosensitive member shaft and D: one rotation cycle of the motor shaft are also reduced. This is considered to be caused by an improvement in the roundness of the drive shaft 86 and the wheel 85, a flywheel effect generated by the rotor of the motor 81, and the like. Thus, when the speed reducer 82 is used, stable driving can be obtained.

The reason why the flywheel effect is generated by the rotor of the motor 81 will be described.
First, the effect of a normal flywheel will be described. The flywheel is generally configured to rotate integrally with a driven part such as a photosensitive drum, and when the rotational speed of the driven part is about to fluctuate, the flywheel is also configured. At the same time, the rotational speed will fluctuate, but the flywheel moment of inertia is set so as to act as a brake against such fluctuation, so fluctuations in the rotational speed of the driven part are also suppressed. It becomes. This is the normal flywheel effect.

  Next, in the case of a normal gear reducer, the gear needs to have backlash, and the rotation of the motor is normally accurately transmitted to a driven part such as a photoconductor, but a sudden load is applied to the driven part. In general, when a situation occurs where the driven part is pushed forward or the driven part is pushed forward by an external force, the motor and the driven part are separated from each other by backlash, and the driven part itself is free to move. Is. Therefore, in the gear drive, the moment of inertia of the motor rotor does not work as a flywheel.

  On the other hand, the reduction gear 82 does not use gears, and the drive transmission unit is always in contact by friction, so there is no backlash. Therefore, when an external force is applied to the driven part and the rotation angle is to be changed, the rotation of the driven part does not change unless the rotor of the motor 81 is rotated at the speed increasing ratio that is the reciprocal of the reduction ratio. Therefore, looking at the magnitude of the rotational moment of the rotor, the inertia moment is a small value compared to a normal flywheel, but the inertia moment of the rotor is a value obtained by multiplying the motor speed increase ratio by the square. Therefore, when the speed increase ratio of the motor is 10 times, the moment of inertia is equivalent to 100 times, and when the speed increase ratio is 20 times, the moment of inertia is equivalent to 400 times, so that the rotor can obtain the same effect as a normal large flywheel. It will be. Note that the condition is that the rotation of the motor is accurately controlled and is maintained in a state where there is little rotation unevenness.

  Hereinafter, various modified examples of the speed reduction device 82 to which the present invention can be applied are shown in FIGS. In each modification, the same reference numerals are given to the same components as those already described, and the description will be omitted as appropriate.

  The reduction gear 82 shown in FIG. 16 will be described. In the reduction gear 82 shown in FIG. 3, the support mode of the motor 81 is a fixed support mode by fixed support, whereas in the reduction gear 82 shown in FIG. 16, the support mode of the motor 81 is displaceable. It has become. Specifically, in the reduction gear 82 shown in FIG. 3, the motor 81 is fixedly supported on the driving side plate 89b which is a non-moving body, whereas in the reduction gear 82 shown in FIG. Displacement means 44 that supports the motor 81 so as to be displaceable with respect to the drive side plate 89b.

  There are various configuration examples of the displacing means 44 as will be described later. In any case, the arrangement purpose of the displacing means 44 is that the positions of the drive shaft 86 and the motor shaft 81a may slightly vary due to errors in the diameter or wear. In consideration of the above, when the drive shaft 86 and the motor shaft 81a rotate out of the original center of rotation and bending stress acts on them, the displacement means 44 displaces the motor 81 so as to absorb the stress. The drive shaft 86 and the motor shaft 81a are prevented from being damaged or the frictional force between the drive shaft 86 and the wheel 85 is reduced, so that the stable pressure contact force of the drive shaft 86 to the wheel 85 is maintained. It is to be.

  The displacement means 44 shown in FIG. 16 includes a rubber 44a as an elastic member, and the motor 81 is supported by the drive side plate 89b via the rubber 44a and can be displaced with respect to the drive side plate 89b. . The rubber 44a has a ring shape, and the motor 81 is screwed with a screw (not shown) so as to sandwich the rubber 44a with the driving side plate 89b. The installation mode of the motor 81 is not limited to this. For example, the motor 81 may be bonded to the rubber 44a and the rubber 44a may be bonded to the drive side plate 89b.

  By having the displacing means 44, when the bending stress described above is applied, the motor 81 is displaced so as to absorb the stress caused by the elastic deformation of the rubber 44a, thereby the drive shaft 86 and the motor shaft 81a. The occurrence of breakage or fluctuations in the frictional force between the drive shaft 86 and the wheel 85 is alleviated, and a stable pressure contact force of the drive shaft 86 with respect to the wheel 85 is maintained.

  A speed reduction device 82 shown in FIG. 17 includes a pressing restricting means 88 having a configuration different from the configuration examples shown in FIGS. 3 and 12. Specifically, the pressing restricting means 88 shown in FIG. 17 contacts and slides on the drive shaft 86 as the restricting member, such as the pressing roller 87a shown in FIG. 3 and the support member 87b shown in FIG. The bearing 87c which is engaged with the drive shaft 86 and supports the drive shaft 86 with respect to the press contact arm 95 is provided. In the drawing, a bearing 87c rotatably supports the drive shaft 86 in a so-called both-side supported manner on both sides of the wheel 85 in the axial direction of the drive shaft 86.

  In this configuration, since the drive shaft 86 is supported and pressed against the circumferential surface 85a in a both-sided state, the efficiency of drive transmission by friction is improved over the entire axial direction. Further, since the restricting member does not slide on the drive shaft 86, the burden on the drive shaft 86 is reduced. Since the drive shaft 86 is a thin shaft-like member, the interval between the bearings 87c and 87c is made as small as possible in order to prevent or reduce the bending and breakage caused by the bending moment caused by the pressure contact with the wheel 85. It is preferable. As the bearing 87c, a normal ball bearing, a needle bearing, or the like can be used.

  The speed reduction device 82 shown in FIG. 18 shows a configuration example having the pressing restricting means 88 using the bearing 87c shown in FIG. 17 and the displacing means 44 shown in FIG. The functions of the restricting means 88 and the displacing means 44 are exhibited simultaneously.

  A reduction gear 82 shown in FIG. 19 shows another configuration example of the pressing restriction means 88 using the bearing 87c shown in FIG. 17, and in the pressing restriction means 88 of this configuration example, the bearing 87c is connected to the drive shaft 86. In the axial direction, the drive shaft 86 is rotatably supported in a so-called cantilever manner on one side opposite to the motor 81 main body with respect to the wheel 85.

  In this configuration, it is possible to reduce the size of the pressing restricting means 88 and to reduce the size of the speed reduction device 82 and the image carrier driving device 80 as compared with the support mode of the drive shaft 86 with both ends shown in FIG. . Further, in this configuration, since it is cantilevered, the tip of the drive shaft 86 can be slightly swung as indicated by an arrow D with the motor 81 main body as the center as compared with the case where both are supported. Therefore, when the above bending stress is applied, the stress is more easily absorbed, and the drive shaft 86 and the motor shaft 81a are damaged, or the frictional force between the drive shaft 86 and the wheel 85 varies. This further relaxes and maintains a more stable pressure contact force of the drive shaft 86 with respect to the wheel 85.

  The cantilever mode is the reverse of that shown in FIG. 19, that is, the bearing 87 c may support the drive shaft 86 on the motor 81 main body side with respect to the wheel 85 in the axial direction of the drive shaft 86. The cantilever in the mode shown in FIG. 19 has a better response to the bending stress described above.

  A reduction gear 82 shown in FIG. 20 shows a configuration example having the pressing restricting means 88 using the bearing 87c shown in FIG. 19 and the displacing means 44 shown in FIG. The functions of the restricting means 88 and the displacing means 44 are exhibited simultaneously.

  In the speed reduction device 82 shown in FIG. 21, compared to the speed reduction device 82 shown in FIG. 20, the displacement means 44 includes the rubber 44 a, and the pressing restriction means 88 presses the drive shaft 86 against the wheel 85. 3 shows a configuration example including a spring 44b as a biasing member that biases the motor 81 in a first direction E1 which is a lower side in the drawing, and a bracket 44c that supports the spring 44b.

  Since the motor 81 is elastically displaceable in the first direction E1 by the rubber 44a, the shaft of the drive shaft 86 with respect to the axial direction of the wheel 85 is pressed by the spring 44b in the first direction E1. The drive shaft 86 is pressed against the circumferential surface 85a in a state where the parallelism of the direction is improved. In order to improve parallelism, the urging force by the spring 44 b is set to a magnitude that generates a rotational moment that balances the rotational moment of the urging force by the spring 97 around the contact point between the drive unit 86 and the wheel 85. The spring 44b has a function of pressing the drive shaft 86 against the wheel 85, and thus can be said to be an urging member provided in the pressing restricting means 88.

  Compared to the speed reduction device 82 shown in FIG. 21, the speed reduction device 82 shown in FIG. 22 does not include the rubber 44 a, and on the other hand, includes a spring 44 b and a bracket 44 c. A configuration example provided with a spring 44d as an urging member for urging the motor 81 in a second direction E2 which is the upper side in the drawing and opposite to the first direction E1, and a bracket 44e supporting the spring 44d. Is shown.

  The motor 81 is supported only by the springs 44b and 44d in the first direction E1 and the second direction E2, and the spring 44d is disposed to support the motor 81 from below. The biasing force that biases the motor 81 in the first direction E1 by the spring 44b is larger than the biasing force that biases the motor 81 in the second direction E2 by the spring 44d. The resultant force of these biasing forces is shown in FIG. The spring 44b in the displacement means 44 is equal to the biasing force that biases the motor 81 in the first direction E1. Even in such a configuration, the drive shaft 86 is pressed against the circumferential surface 85a in a state where the parallelism of the drive shaft 86 with respect to the axial direction of the wheel 85 is improved. In this case as well, the spring 44b has a function of pressing the drive shaft 86 against the wheel 85, so that it can be said that the spring 44b is an urging member provided in the pressing restricting means 88.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to this specific embodiment, Unless it is specifically limited by the above-mentioned description, this invention described in the claim is described. Various modifications and changes are possible within the scope of the gist of the invention.

  For example, the pressing restricting means may include not only one of the driven member and the bearing, but also both of them. The displacement means may include an elastic member even when it has the second urging member.

  The present invention can also be applied to an image forming apparatus of a so-called intermediate transfer system in which toner images of respective colors are sequentially transferred onto an intermediate transfer member and transferred to a recording medium in a lump. It is. The present invention can also be applied to a so-called one-drum type image forming apparatus that sequentially forms toner images of respective colors on a single photosensitive drum and sequentially superimposes the color toner images to obtain a color image. The present invention can also be applied to an image forming apparatus capable of monochrome image formation.

  The effects described in the embodiments of the present invention are only the most preferable effects resulting from the present invention, and the effects of the present invention are limited to those described in the embodiments of the present invention. is not.

  As described above, according to the present embodiment, when a force in the rotational axis direction is generated on the drive shaft 86 that is rotationally driven by the motor 81 as the drive source, the drive shaft 86 is pressed toward the wheel 85 as the drive transmission member. As the pressing restricting means 88 swings, the parallelism of both rotation axes is automatically corrected so that the rotation axis of the drive shaft 86 and the rotation axis of the wheel 85 are parallel. Moreover, the mechanism for swinging the pressure restricting means 88 is more suitable than the case where the precision of the components of the pressure restricting means 88 is increased or the assembly accuracy is increased in order to make the two rotation shafts parallel. It can be manufactured at low cost. Therefore, it is possible to suppress the increase in manufacturing cost, suppress the deviation in the rotation axis direction of the member that performs the drive transmission due to friction, and perform the drive transmission while more reliably suppressing the fluctuation of the rotation speed.

  Further, according to the above embodiment, the shaft adjustment swing fulcrum portion 111 having the swing support point of the press restricting means 88 and the shaft adjustment swing guide portion 120 for guiding the swing of the press restricting means 88 are provided. The shaft adjustment swinging fulcrum 111 is provided at a position away from the installation position of the drive shaft 86 in the direction of the reaction force that the drive shaft 86 receives from the wheel 85 as a drive transmission member when the drive shaft 86 rotates. . As a result, the pressure regulating means 88 is centered on the fulcrum of the shaft adjustment swing fulcrum 111 according to the force in the direction of the rotation axis that acts on the drive shaft 86 when the drive shaft 86 rotates. Then, it is swung like a caster and automatically corrected so that the rotation axis of the drive shaft 86 maintains parallelism with the rotation axis of the wheel 85.

  Further, according to the above-described embodiment, the pressing restricting means 88 holds the motor 81 as a drive source, so that the pressing restricting means 88 and the motor 81 coupled to the drive shaft 86 swing integrally. Therefore, the motor 81 does not hinder the automatic correction of the parallelism of the rotation axis of the drive shaft 86 with respect to the rotation axis of the wheel 85.

  Further, according to the above embodiment, the drive shaft 86 is driven and transmitted from the motor 81 as the drive source via the flexible joint 110 as the coupling, so that the rotation axis of the drive shaft 86 is automatically corrected. Since the rotation axis of the drive shaft 86 and the output shaft of the motor 81 can be inclined at the flexible joint 110, the motor 81 can automatically correct the parallelism of the rotation axis of the drive shaft 86 with respect to the rotation axis of the wheel 85. There is no hindrance.

  In addition, according to the above embodiment, the shaft adjustment swing fulcrum 111 has the spring 97 as a pressure member for pressing the drive shaft 86 toward the rotation center of the wheel 85 as a drive transmission member, The shaft adjustment swing guide portion 120 includes a shaft 96 as a press swing support member serving as a press swing support of the press restricting means 88 for pressing the drive shaft 86, and a support member that rotatably supports the shaft 96. As a pivot support bracket 112. As a result, a press swing mechanism for pressing the drive shaft 86 and a shaft adjustment swing for automatically correcting the rotation shaft of the drive shaft 86 so as to maintain parallelism with the rotation shaft of the wheel 85. Since the mechanism can be configured integrally, an increase in manufacturing cost can be further suppressed.

  Further, according to the above embodiment, the shaft support bracket 112 is formed with the long hole 112a in which the shaft 96 as the pressing / swinging fulcrum member is movably engaged when the shaft regulating swinging of the pressing regulating means 88 is performed. Therefore, the shaft 96 is fitted and supported while rotating or sliding in the elongated hole 112a, and the shaft regulating swing of the pressing restricting means 88 can be performed smoothly.

  Further, according to the above embodiment, the shaft support bracket 112 is configured to be deformable in accordance with the shaft adjustment swing of the pressing swing means 88, so that the shaft support bracket 112 and the shaft 96 can be moved together with the swing. Sliding can be reduced, and the life of parts can be extended.

  Further, according to the above embodiment, the pressing swing fulcrum member is the roller 114, and the shaft support bracket 112 is configured to support the roller 114, thereby rolling contact at the contact portion with the press contact arm 95. Can reduce sliding friction

  Moreover, according to the said embodiment, by using the spherical roller 114 or the cylindrical roller 114b as said roller, it can comprise using a cheap commercial item and can further suppress the increase in manufacturing cost.

  In addition, according to the above-described embodiment, the spring 97 as a pressure member for pressing the shaft adjustment swing guide portion 121 toward the rotation center of the wheel 85 as the drive transmission member, and the spring A screw 98 as a pressure support member that supports 97 and an engaging portion that engages with the screw 98, and the shaft adjustment swing fulcrum portion 111 is pressed to press the drive shaft 86. A flange 113 having a hemispherical convex portion 113a as a pressing oscillating fulcrum member serving as a fulcrum of the regulating means 88, and a concave portion 95c as a support portion that rotatably receives and supports the convex portion 113a of the flange 113. With this configuration, even when the rotation direction of the drive shaft 86 is reverse, the drive shaft 86 follows the wheel 85 like a caster, and the rotation shaft of the drive shaft 86 is It can be automatically corrected so as to maintain the parallelism between the rolling axis.

  Further, according to the above-described embodiment, the long hole 95d is formed in the engaging portion so that the spring 97 as the pressure support member is movably engaged when the shaft regulating swing of the pressing restricting means 88 is swayed. With this configuration, the press contact arm 95 can swing about the swing support point 113b.

  In addition, according to the above-described embodiment, the pressure contact roller 87a as the restriction member is provided at a position facing the circumferential surface of the wheel 85, and the drive shaft 86 is restricted at this position. The pressure contact roller 87a and the drive shaft By providing at least two contact points with the peripheral surface of the drive shaft 86 on the side opposite to the peripheral surface of the drive shaft 86, the wheel 85 can be circled without bending the drive shaft 86 by the pressing roller 87a. The drive shaft 86 is positioned well over the entire width of the peripheral surface, and smooth drive transmission due to friction can be used to reliably perform drive transmission while suppressing fluctuations in rotational speed. It is possible to provide a reduction gear that can be reduced in size with a reduction ratio, and that can function as a flywheel by controlling the rotation of the motor rotor. .

  Further, according to the above-described embodiment, the position of the contact is determined by the resultant force of the force that the pressing roller 87a as the pressing restricting means 88 presses the drive shaft 86 toward the circumferential surface of the wheel 85 at the contact. Since the position 86 is a direction toward the rotation center of the wheel 85, the drive shaft 86 can be positioned more favorably by the pressure contact roller 87a that forms the contact point.

  Further, according to the above embodiment, the position of the contact is symmetrical with respect to a straight line connecting the rotation center of the drive shaft 86 and the rotation center of the wheel 85, so that the pressure contact roller 87a that forms the contact is formed. As a result, the displacement of the drive shaft 86 can be highly suppressed and positioning can be performed satisfactorily.

  In addition, according to the above-described embodiment, the press contact roller 87a is the two press contact rollers 87a that are in contact with the drive shaft 86 and can be driven to rotate by the drive shaft 86, so that the wear of the drive shaft 86 is caused by the two press contact rollers 87a. Can be suppressed.

  Moreover, according to the said embodiment, since the said 2 press-contact roller 87a is a ball bearing or a roller bearing, abrasion of the drive shaft 86 can further be suppressed by the 2 press-contact roller 87a with favorable rotation.

  Further, according to the embodiment, the support member 87b as the restricting member has the substantially U-shaped, substantially V-shaped or polygonal recess 87b1, and the contact with the drive shaft 86 in the recess 87b1. The positioning of the drive shaft 86 can be easily and satisfactorily performed by the restriction member having a relatively simple configuration.

  Further, according to the above-described embodiment, the restriction member is a bearing 87c that rotatably supports the drive shaft 86 on both sides of the wheel 85 in the axial direction of the drive shaft 86, and thus is rotated by the bearing 87c. The drive shaft 86 which is freely supported with high positioning accuracy can use smooth drive transmission by friction with high efficiency.

  Further, according to the above-described embodiment, the regulating member is the bearing 87c that supports the drive shaft 86 so as to be rotatable on the side opposite to the motor 81 as the drive source with respect to the wheel 85 in the axial direction of the drive shaft 86. As a result, smooth drive transmission by friction can be used by the drive shaft 86 supported by the bearing 87c in a rotatable and relatively simple configuration.

  Moreover, in the said embodiment, you may comprise the drive shaft 86 so that it may have a U-shaped groove | channel as a flexible part which narrowed the shaft diameter in the root part. In this case, the contact between the drive shaft 86 and the wheel 85 can be satisfactorily performed by the bending of the drive shaft 86.

  Moreover, according to the said embodiment, it has the displacement means which supported the motor 81 so that displacement was possible with respect to the stationary body 89 for supporting the motor 81 as a drive source, and contact | abutted with the wheel 85 by a displacement means. Thus, the contact with the wheel 85 can be satisfactorily performed while suppressing the drive shaft 86 from being bent.

  Further, according to the above embodiment, the displacement means has the elastic member 44a that supports the drive source 81 so as to be displaceable with respect to the non-moving body 89, so that the elastic member 44a is driven by contact with the wheel 85. It is possible to satisfactorily make contact with the wheel 85 while suppressing the shaft 86 from being bent.

  Further, according to the embodiment, the displacing means includes the urging member 44 b that urges the motor 81 as the driving source in the first direction in which the pressing restricting means 88 presses the drive shaft 86 against the wheel 85. As a result, the urging members 44b can improve the parallelism of the rotation center axes of the drive shaft 86 and the wheel 85.

  Further, according to the above-described embodiment, the urging member includes the first urging member 44b for urging the motor 81 as a drive source in the first direction and the motor 81 in the first direction. A second urging member 44d for urging in the opposite second direction, and the urging force by which the first urging member 44b urges the motor 81 in the first direction is the second urging force. By configuring the biasing member 44d to be larger than the biasing force that biases the motor 81 in the second direction, the drive shaft 86 is supported while the motor 81 is supported by the first and second biasing members 44b and 44d. The parallelism of the rotation center axes of the wheels 85 can be improved.

  Further, according to the above embodiment, the drive shaft 86 and the wheel 85 are made of metal, and the lubricating means is provided to lubricate the space between the drive shaft 86 and the circumferential surface of the wheel 85 with the lubricant. The deformation and wear of the drive shaft 86 and the wheel 85 can be suppressed.

  Further, according to the above embodiment, by using traction oil as the lubricant, it is possible to suppress wear while increasing the coefficient of friction between the drive shaft 86 and the wheel 85.

  Further, according to the above embodiment, the encoder sensor 92 serving as a rotational speed detecting means for detecting the rotational speed of the wheel 85, and the rotational speed of the drive shaft 86 so as to keep the rotational speed detected by the encoder sensor 92 constant. By having the motor control circuit 41 as a rotational speed control means for controlling the control, it is possible to perform control so as to keep the rotational speed of the wheel 85 constant while using smooth drive transmission by friction.

  Further, the present invention includes the speed reducing device 82 and the drive source 81 having the drive shaft 86, and the photosensitive drum 20 as an image carrier by the driving force of the drive source 81 through the wheel 85. The image carrier driving device 80 that rotationally drives the motor can reliably transmit the drive while suppressing fluctuations in the rotational speed while using smooth drive transmission due to friction, and at a higher reduction ratio than the gear. It is possible to reduce the rotational speed of the drive source 81 in a highly constant state by a reduction device 82 that can be reduced in size and that can function as a flywheel to suppress rotation fluctuations. By driving the body drum 20, the image bearing body driving device 80 that can drive the photosensitive drum 20 at a constant speed with high accuracy and contribute to good image formation is provided. It can be provided.

  Further, since the present invention is in the image forming apparatus 100 having the image carrier driving device 80 and the photosensitive drum 20 that is rotationally driven by the image carrier driving device 80, smooth drive transmission by friction is used. In addition to being able to reliably transmit drive while suppressing fluctuations in rotational speed, it is possible to reduce the size with a high reduction ratio compared to gears, and to function as a flywheel by rotating the motor rotor. By the image carrier driving device 80 including the reduction device 82 that can be suppressed, the rotational speed of the driving source 81 is decelerated in a highly constant state to drive the photosensitive drum 20 at a constant speed with high accuracy. Therefore, it is possible to provide the image forming apparatus 100 that can perform good image formation.

20, 20Y, 20M, 20C, 20BK Image carrier 41 Rotational speed control means 44 Displacement means 44a Elastic member 44b Biasing member, first biasing member 44d Second biasing member 80, 80Y, 80M, 80C, 80BK Image carrier driving device 81, 81Y, 81M, 81C, 81BK Drive source 82 Deceleration device 85 Drive transmission member 85a Circumferential surface 86 Drive shaft 87a, 87b, 87c Restriction member 87a Pressure contact roller 87b Support member 87b1 Depression 87c Bearing 88 Press restriction Means 89, 89b Non-moving body 92 Rotational speed detecting means 93 Lubricating means 94 Lubricant, traction oil 95 Pressing arm 95a Shaft mounting part 95c Recess 95 Pressing arm 96 Shaft 98 Screw 98a Swing fulcrum 100 Image forming apparatus 110 Flexible joint 111 Shaking Dynamic fulcrum 112 Shaft support bracket 112a Long hole 113 Flange 113a Hemispherical convex 113b Swing fulcrum 114 Roller 114b Cylindrical roller 120, 121 Shaft adjustment swing guide part E1 First direction E2 Second direction

JP 2001-134138 A JP-A-10-288915 Japanese Patent Application Laid-Open No. 2002-171779 JP 2000-346144 A Japanese Patent No. 2981295

Claims (28)

A drive shaft that is rotationally driven by a drive source;
A drive transmission member that has a circumferential surface that abuts on the drive shaft and is rotationally driven by the drive shaft, and that decelerates the drive from the drive source and transmits it to the image carrier,
A pressing member that has a restricting member for restricting the shift of the drive shaft in the rotation direction of the drive transmission member and presses the drive shaft toward the rotation center of the drive transmission member;
The pressing restricting means is configured to hold the drive source and swing in a direction to suppress the force in the rotation axis direction of the drive shaft according to the force in the rotation axis direction of the drive shaft. Characteristic reduction gear. A drive shaft that is rotationally driven by a drive source;
A drive transmission member having a circumferential surface abutting on the drive shaft and driven to rotate by the drive shaft, wherein the drive device decelerates the drive from the drive source and transmits it to the image carrier,
A pressing member that has a restricting member for restricting the shift of the drive shaft in the rotation direction of the drive transmission member and presses the drive shaft toward the rotation center of the drive transmission member;
The drive shaft is driven and transmitted from the drive source via a coupling,
The reduction device according to claim 1, wherein the pressing restricting means is configured to be swingable in a direction to suppress a force in the rotation axis direction of the drive shaft in accordance with a force in the rotation direction of the drive shaft. The reduction gear according to claim 1 or 2,
A shaft adjustment swing fulcrum portion having a swing fulcrum of the pressure restricting means, and an axis adjustment swing guide portion for guiding the swing of the press restricting means,
The shaft adjustment swing fulcrum portion is provided at a position away from an installation position of the drive shaft in a direction of a reaction force that the drive shaft receives from the drive transmission member when the drive shaft rotates. To reduce the speed. The speed reducer according to claim 3,
The shaft adjustment swing fulcrum has a pressure member for pressing the drive shaft toward the rotation center of the drive transmission member,
The shaft adjustment swing guide portion includes a press swing support member serving as a swing support point of the press restricting means for pressing the drive shaft, and a support member that rotatably supports the press swing support member. A speed reducer comprising: The speed reducer according to claim 4,
The speed reducer according to claim 1, wherein the support member is formed with a hole for movably engaging the pressing swing fulcrum member when the pressing restricting means swings. The speed reducer according to claim 4 or 5,
The speed reduction device according to claim 1, wherein the support member is configured to be deformable in response to swinging of the pressing restricting means. The speed reducer according to claim 4,
The pressing swing fulcrum member is a roller,
The speed reducing device, wherein the support member is configured to support the roller. The speed reducer according to claim 7,
The roller is a spherical roller or a cylindrical roller. The speed reducer according to claim 3,
The shaft adjustment swing guide portion includes a pressure member for pressing the drive shaft toward the rotation center of the drive transmission member, a pressure support member for supporting the pressure member, and the pressure support member. And an engaging portion that engages with
The shaft adjustment swing fulcrum is a press swing support member that serves as a swing support for the press restricting means for pressing the drive shaft, and a support that rotatably receives and supports the press swing support member. And a speed reducing device. The speed reducer according to claim 9,
The speed reducing device according to claim 1, wherein a hole is formed in the engaging portion so that the pressing support member is movably engaged when the pressing restricting means swings. The speed reducer according to any one of claims 1 to 10,
The regulating member is provided at a position facing the circumferential surface, and regulates the drive shaft at this position,
A speed reducer having at least two contact points between the restriction member and the drive shaft on a peripheral surface of the drive shaft opposite to the peripheral surface facing the drive transmission member. The speed reducer according to claim 11,
The position of the contact is a position where the resultant force of the force that the pressing restricting means presses the drive shaft toward the circumferential surface at the contact is a direction in which the drive shaft is directed toward the rotation center of the drive transmission member. A reduction gear characterized by being. The speed reducer according to claim 11 or 12,
The speed reducing device according to claim 1, wherein the position of the contact point is symmetrical with respect to a straight line connecting the rotation center of the drive shaft and the rotation center of the drive transmission member. The reduction gear according to any one of claims 11 to 13,
The speed reducing device according to claim 1, wherein the restricting member is two pressure contact rollers that abut against the drive shaft and can be driven to rotate by the drive shaft. The speed reducer according to claim 14,
The two pressure contact rollers are ball bearings or roller bearings. The reduction gear according to any one of claims 11 to 13,
The restriction member has a substantially U-shaped, substantially V-shaped or polygonal depression, and abuts against the drive shaft in the depression. The speed reducer according to any one of claims 1 to 10,
The speed reducing device, wherein the regulating member is a bearing that rotatably supports the drive shaft on both sides of the drive transmission member in the axial direction of the drive shaft. The speed reducer according to any one of claims 1 to 10,
The speed reduction device according to claim 1, wherein the restricting member is a bearing that rotatably supports the drive shaft in a direction opposite to the drive source with respect to the drive transmission member in an axial direction of the drive shaft. The reduction gear according to any one of claims 1 to 18,
The drive shaft has a flexible portion with a narrowed shaft diameter at a base portion thereof. The reduction gear according to any one of claims 1 to 19,
A speed reducer comprising a displacement means for supporting the drive source so as to be displaceable with respect to a non-moving body for supporting the drive source. The speed reducer according to claim 20,
The said displacement means has the elastic member which supported the said drive source so that a displacement with respect to the said non-moving body was possible. The reduction gear according to claim 20 or 21,
The speed reducing device, wherein the displacement means includes a biasing member that biases the drive source in a first direction in which the pressing restriction means presses the drive shaft against the drive transmission member. The reduction gear according to claim 20 or 21,
The urging member includes a first urging member for urging the driving source in a first direction, and an urging member for urging the driving source in a second direction opposite to the first direction. A second biasing member, and the first biasing member biases the drive source in the first direction. The second biasing member biases the drive source in the second direction. A speed reducer characterized in that it is larger than the biasing force. The reduction gear according to any one of claims 1 to 23,
The speed reduction device according to claim 1, wherein the drive shaft and the drive transmission member are made of metal, and have a lubricating means for lubricating the drive shaft and the circumferential surface with a lubricant. The reduction gear according to claim 24,
A speed reducer, wherein the lubricant is traction oil. The reduction gear according to any one of claims 1 to 25,
A rotational speed detecting means for detecting the rotational speed of the drive transmission member;
A speed reduction device comprising: a rotation speed control means for controlling the rotation speed of the drive shaft so as to keep the rotation speed detected by the rotation speed detection means constant. A reduction gear according to any one of claims 1 to 26;
The drive source having the drive shaft,
An image carrier driving apparatus that rotationally drives the image carrier by the driving force of the drive source via the drive transmission member.   An image forming apparatus comprising: the image carrier driving device according to claim 27; and an image carrier that is rotationally driven by the image carrier driving device.

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