JP2011028167A - Rotation transfer device and image forming apparatus including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotation transfer device which smoothly and reliably connects/disconnects rotation between two shafts and which prevents backlash of a coupling member, thus achieving precise rotation transfer. <P>SOLUTION: The rotation transfer device 30 transfers rotation between a drive shaft 31 and a driven shaft 32 by a coupling member 34 on the outer periphery of the driven shaft 32 slidably in the shaft direction and non-rotatably in the circumferential direction, by engaging the tip part of the driven shaft 32 with an engagement hole 31a formed on the end shaft center of the driven shaft 31, by unevenly engaging the coupling member 34 with the drive shaft 31, and by energizing the coupling member 34 in the engagement direction by a spring 37. The degree of engagement of the coupling member 34 with the driven shaft 32 is made different before and after the uneven engagement of the coupling member 34 with the drive shaft 31. The degree of engagement after the uneven engagement of the coupling member 34 is made as high as possible within the limit of being slidable. The degree of engagement before the uneven engagement of the coupling member 34 is made lower than that after the uneven engagement. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a rotation transmission device for transmitting rotation between two coaxially arranged shafts, and an image forming apparatus such as a copying machine and a printer equipped with the rotation transmission device.

  For example, in an image forming apparatus such as a copying machine or a printer that employs an electrophotographic system, a latent image formed on an image carrier such as a photosensitive drum that is rotationally driven at a predetermined speed (process speed) is developed with toner. The toner image is visualized as a toner image, the toner image is transferred onto the recording material, and then the toner image is heated and pressurized to be fixed on the recording material to form an image on the recording material. Is done.

  In such an image forming apparatus, in consideration of maintenance and the like, peripheral devices such as an image carrier and a charger arranged around the image carrier are integrated as a cartridge, and the cartridge is attached to and detached from the image forming apparatus main body. Often the configuration is adopted. When such a configuration is adopted, a rotation transmission device capable of connecting and disconnecting the rotation transmission to the image carrier included in the cartridge is indispensable when the cartridge is attached and detached.

  In the rotation transmitting device, a coupling member is slidable in the axial direction and non-rotatable in the circumferential direction on the outer periphery of the first shaft of the first and second shafts arranged coaxially, and the second A front end portion of the first shaft is fitted into a fitting recess formed in an end shaft center of the shaft, and the coupling member is concavo-convexly fitted to the second shaft, and the coupling member is It is configured to transmit rotation between the first shaft and the second shaft by urging in the fitting direction. In such a rotation transmission device, if the degree of fitting between the coupling member and the first shaft is set to be loose in order to improve the slidability of the coupling member, the coupling member is loose on the first shaft. As a result, problems such as the occurrence of vibration in the rotation of the image carrier and the generation of jitter (vertical lines) in the image occur.

  Therefore, for example, in Patent Document 1, as shown in FIG. 10, a drive transmission member (coupling member) 134 fitted to the outer periphery of the drive shaft (first shaft) has a tapered shape whose width changes in the axial direction. A long hole 134a is formed, and the pin 135 penetrating the drive shaft is fitted into the long hole 134a. When the drive shaft and the driven shaft are separated, the degree of fitting between the long hole 134a and the pin 135 is loosened. After the drive shaft 134 and the driven shaft are connected to each other, the sliding force of the drive transmission member 134 is improved, and the degree of fitting between the long hole 134a and the pin 135 is tightened to eliminate the backlash of the drive transmission member 134, thereby vibrating the photosensitive drum. A configuration has been proposed in which the occurrence of image defects is prevented by suppressing the occurrence of image defects.

Japanese Patent No. 4037044

  However, in the configuration shown in FIG. 10 proposed in Patent Document 1, the effect is easily influenced by the dimensional accuracy of the long hole 134 a and the pin 135 formed in the drive transmission member 134, and the shaft between the drive transmission member 134 and the drive shaft. There is a problem that it is not easy to make the hearts coincide with each other with high accuracy and eliminate the play of the drive transmission member 134.

  The present invention has been made in view of the above problems, and the object of the process is to smoothly and reliably connect and disconnect the rotation between the two shafts, and to easily and reliably eliminate the rattling of the coupling member. An object of the present invention is to provide a rotation transmission device that enables accurate rotation transmission, and an image forming apparatus that can stably obtain a high-quality image by suppressing rotational vibration of an image carrier.

  In order to achieve the above object, according to the first aspect of the present invention, the coupling member is slidable in the axial direction and rotated in the circumferential direction on the outer periphery of the first shaft of the first and second shafts arranged coaxially. The tip of the first shaft is fitted into a fitting hole formed in the end shaft center of the second shaft, and the coupling member is concavo-convexly fitted to the second shaft. And a rotation transmitting device that transmits rotation between the first shaft and the second shaft by urging the coupling member in the fitting direction, and the second shaft of the coupling member The degree of fitting between the coupling member and the first shaft is changed before and after the concave / convex fitting to the fitting, and the fitting degree after the concave / convex fitting of the coupling member is as tight as possible within the slidable limit. That the coupling member before fitting the concave and convex portions is looser than the fitting degree after fitting. And butterflies.

  According to a second aspect of the present invention, in the first aspect of the present invention, a large-diameter portion is formed on a part of the first shaft in a sliding range of the coupling member.

  According to a third aspect of the present invention, in the first aspect of the present invention, the outer diameter from the tip of the first shaft to the sliding range of the coupling member is set constant and larger than the outer diameter of other portions. It is characterized by that.

  According to a fourth aspect of the present invention, the latent image formed on the rotationally driven image carrier is developed as a toner image with toner, and the toner image is transferred onto the recording material. An image forming apparatus for forming an image on a recording material through an electrophotographic process for fixing, wherein the rotation transmission device according to any one of claims 1 to 3 is provided in a drive transmission path from a drive source to the image carrier. It is characterized by that.

  According to the first aspect of the present invention, the axial center of the first shaft and the coupling member diameter (outer diameter and inner diameter) is provided so that the fitting degree of the coupling member after the concave-convex fitting is slid. Since it is as tight as possible to the extent that it can be moved, rattling of the coupling member during rotation transmission can be easily and reliably suppressed, and highly accurate rotation transmission is possible. In addition, since the degree of fitting of the coupling member before the concave-convex fitting is made looser than the degree of fitting after the fitting, the coupling member can smoothly slide on the first shaft, and the rotation transmission and disconnection can be made. Is surely made.

  According to invention of Claim 2 and 3, since the large diameter part formed in the 1st axis | shaft remove | deviates from the internal diameter part of a coupling member before a coupling member carries out uneven | corrugated fitting with respect to a 2nd axis | shaft. When the coupling member is loosened and the coupling member is concavo-convexly fitted to the second shaft, the large-diameter portion formed on the first shaft fits into the inner diameter portion of the coupling member. Therefore, the degree of fitting of the coupling member becomes tight and the rattling is suppressed, and highly accurate rotation transmission becomes possible.

  According to the fourth aspect of the present invention, the rotation transmission / reception device provided in the image forming apparatus can smoothly and surely connect and disconnect the rotation between the two axes, and the backlash of the coupling member can be suppressed to achieve high accuracy. Therefore, the image carrier can be attached and detached smoothly and reliably, and high-quality images can be stably obtained by suppressing the rotational vibration of the image carrier.

1 is a side sectional view of an image forming apparatus (laser printer) according to the present invention. 1 is an exploded perspective view of a rotation transmission device according to a first embodiment of the present invention. It is a sectional side view of the driven shaft of the rotation transmission apparatus which concerns on Embodiment 1 of this invention. It is a perspective view of the coupling member of the rotation transmission device according to the first embodiment of the present invention. (A)-(c) is a plane sectional view which shows the connection procedure of the rotation transmission apparatus which concerns on Embodiment 1 of this invention. (A)-(c) is a side view which shows the connection procedure of the rotation transmission apparatus which concerns on Embodiment 1 of this invention. It is a disassembled perspective view of the rotation transmission apparatus which concerns on Embodiment 2 of this invention. It is a sectional side view of the driven shaft of the rotation transmission apparatus which concerns on Embodiment 2 of this invention. (A)-(c) is a plane sectional view which shows the connection procedure of the rotation transmission apparatus which concerns on Embodiment 2 of this invention. It is a top view of the drive transmission member of the conventional rotation transmission apparatus.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

[Image forming apparatus]
FIG. 1 is a side sectional view of a laser printer as an embodiment of an image forming apparatus according to the present invention. In the illustrated laser printer 1, a central portion of the upper surface of a rectangular box-shaped printer main body (image forming apparatus main body) 2 is shown. In addition, an inclined concave paper discharge tray 3 is provided. An openable and closable manual feed tray 4 is provided at the upper part of the front surface of the printer main body 2 (the right side in FIG. 1 is the front). The manual feed tray 4 and a manual feed tray that is rotatably provided in the printer main body 2 at the back thereof. The sheet feeding roller 5 constitutes a manual sheet feeding unit 6.

  Thus, the laser printer 1 transfers the paper P based on image data transmitted from a terminal (not shown) while transporting the paper P as a recording material along the transport path L provided in the printer body 2. The transport path L is formed in a substantially L shape in a side view and extends to the paper discharge tray 3.

  The laser printer 1 includes a cassette paper feeding unit 7 provided at a lower portion of the printer main body 2, an image forming unit 8 provided at a substantially central portion in the printer main body 2 above the cassette paper feeding unit 7, A fixing device 9 disposed behind the image forming unit 8 and a concave paper discharge unit 10 provided on the upper surface of the printer main body 2 above the fixing device 9 are provided.

  The cassette sheet feeding unit 7 stacks and stores a plurality of sheets of paper P in a rectangular tray-shaped sheet feeding cassette 11 having an open upper surface, and picks a roller 12 that picks up the sheets P in the sheet feeding cassette 11 one by one. And a feed roller 13 and a retard roller 14 for separating the taken paper P one by one and feeding them to the transport path L. The transport path L has a predetermined length after the fed paper P is temporarily held. A registration roller pair 15 is provided to be supplied to the image forming unit 8 at this timing.

  The image forming unit 8 forms an image corresponding to the image data on the paper P supplied one by one from the manual paper feeding unit 6 or the cassette paper feeding unit 7. A photosensitive drum 16 as an image carrier that is rotatably arranged on the printer, a charger 17 disposed around the photosensitive drum 16, a developing device 18 that is a developing unit, a transfer roller 19 that is a transfer unit, and a cleaning device 20, and the like. A laser scanner unit (LSU) 21 disposed above, a toner hopper 22 containing replenishing toner, and the like are provided.

  The fixing device 9 is for fixing the toner image transferred onto the paper P in the image forming unit 8 to the paper P, and includes a fixing roller 23 and a pressure roller 24 that rotate while being pressed against each other. I have. The fixing roller 23 incorporates a heating means such as a heater, and the pressure roller 24 is pressed against the fixing roller 23 by a biasing means such as a spring with a predetermined pressure. Is formed.

  Further, the paper discharge unit 10 is for discharging the paper P on which the toner image has been fixed in the fixing device 9 to the outside of the printer main body 2, and is a pair of upper and lower discharges provided at the end of the conveyance path L. A pair of paper rollers 25, a plurality of vertical rib-shaped conveyance guide ribs 26 for guiding the sheet P conveyed from the fixing device 9 along the conveyance path L to the sheet discharge roller pair 25, and the printer body 2 are discharged. The paper discharge tray 3 for loading the paper P to be printed is provided.

  Next, an image forming operation of the laser printer 1 having the above configuration will be described.

  For example, when a print start signal is transmitted to the laser printer 1 from a terminal such as a personal computer (personal computer), the photosensitive drum 16 is moved in the direction indicated by the arrow (clockwise) in FIG. ) At a predetermined process speed, and its surface is uniformly charged to a predetermined potential by the charger 17. When a laser beam based on the image data transmitted from the terminal is output from the laser scanner unit 21 and irradiated onto the photosensitive drum 16, an electrostatic latent image corresponding to the image data is formed on the photosensitive drum 16. Is done. Then, the electrostatic latent image formed on the photosensitive drum 16 is developed by the developing device 18 using toner as a developer to be visualized as a toner image.

  By the way, when cassette feeding is performed, the paper P stored in the paper feeding cassette 11 of the cassette paper feeding unit 7 is picked up one by one from the uppermost one by the pick roller 12, and the feed roller 13 and the retard roller 14. Are separated one by one and conveyed to the registration roller pair 15. In the registration roller pair 15, the paper P is temporarily put into a standby state and then supplied to the image forming unit 8 at a predetermined timing synchronized with the toner image on the photosensitive drum 16.

  In the image forming unit 8, the sheet P supplied to the transfer nip between the photosensitive drum 16 and the transfer roller 19 is conveyed while being pressed against the photosensitive drum 16 by the transfer roller 19, so that the surface (transfer) The toner image on the photosensitive drum 16 is transferred onto the surface. The sheet P on which the toner image has been transferred is conveyed to the fixing device 9 where it is heated and pressurized in the process of being sandwiched and conveyed by the fixing nip between the fixing roller 23 and the pressure roller 24. The toner image is fixed. The toner remaining on the surface of the photosensitive drum 16 (transfer residual toner) after the transfer of the toner image onto the paper P is removed by the cleaning device 20, and the photosensitive drum 16 whose surface has been cleaned is prepared for the next image forming operation. .

  Thus, the sheet P having the toner image fixed on the surface thereof by the fixing device 9 is conveyed upward along the conveyance path L toward the sheet discharge unit 10, and along the conveyance guide rib 26 to the pair of sheet discharge rollers 25. And is fed out of the printer main body 2 while being sandwiched between the pair of paper discharge rollers 25 and stacked on the paper discharge tray 3 provided on the upper portion of the printer main body 2, and a series of image forming operations is completed. .

  When the user manually feeds the paper, the paper P stacked on the manual tray 4 of the manual paper feed unit 6 is supplied to the registration roller pair 15 by the manual paper feed roller 5. Through the same process, an image is formed on the paper P, and the paper P on which the image is formed is stacked on the paper discharge tray 3 outside the printer main body 2.

[Rotation transmission device]
Next, an embodiment of the rotation transmission device according to the present invention will be described.

<Embodiment 1>
2 is an exploded perspective view of the rotation transmission device according to Embodiment 1 of the present invention, FIG. 3 is a side sectional view of a driven shaft of the rotation transmission device, and FIG. 4 is a perspective view of a coupling member of the rotation transmission device. FIGS. 5A to 5C are plan sectional views showing the connection procedure of the rotation transmission device, and FIGS. 6A to 6C are side views showing the connection procedure of the rotation transmission device.

  As shown in FIGS. 2, 5, and 6, the rotation transmission device 30 according to the present invention includes a drive shaft 31 and a driven shaft 32 that are coaxially arranged, and the driven shaft of the drive shaft 31. As shown in FIG. 5, a circular fitting hole 31a is formed over a predetermined length at the axial center of one end in the axial direction on the side facing 32, and the end of the drive shaft 31 is cylindrical. It is formed in a shape. Then, two fitting grooves 31b having a rectangular groove shape are formed on the end face in the axial direction facing the driven shaft 32 of the drive shaft 31 at a 180 ° pitch.

  On the other hand, the driven shaft 32 constitutes the rotating shaft of the photosensitive drum 16 and is inserted and fixed to the central portion of the photosensitive drum 16. A drum gear 33 is bound to the outer periphery of one end of the photosensitive drum 16 in the axial direction. A substantially cylindrical coupling member 34 as shown in FIG. 4 is provided on the outer periphery of an axial end portion (an axial end opposite to the drive shaft 31) of the driven shaft 32 protruding in the axial direction from the photosensitive drum 16. Are slidable in the axial direction and non-rotatable in the circumferential direction.

  As shown in FIG. 4, two convex portions 34A are integrally formed at two opposite locations on the outer periphery of the coupling member 34, and each convex portion 34A opens toward the drive shaft 31 side. Engaging grooves 34a are respectively formed. Further, the coupling member 34 is fitted into the fitting groove 31b formed on the one end face of the drive shaft 31 at two opposing positions between the convex portions 34A on the end face of the coupling member 34 facing the drive shaft 31. Two fitting protrusions 34b having a rectangular claw shape are integrally formed.

  Here, the outer diameter of the end of the driven shaft 32 protruding from the axial end of the photosensitive drum 16 toward the drive shaft 31 is larger than the inner diameter of the fitting hole 31 a formed at one end of the drive shaft 31 in the axial direction. It is set to be slightly smaller, and a round bar-like pin 35 is inserted and fixed in the direction perpendicular to the axis at the end of the driven shaft 32. The tip of the driven shaft 32 is formed in a conical shape that tapers in the direction of the drive shaft 31. The coupling member 34 is fitted to the outer periphery of the end of the driven shaft 32 so as to be slidable in the axial direction, and is formed on the coupling member 34 as shown in FIGS. The axially opposite ends of the pin 35 are engaged with the two engaging grooves 34a, respectively, so that the coupling member 34 cannot rotate in the circumferential direction with respect to the driven shaft 32 (can rotate integrally with the driven shaft 32). It is connected.

  As shown in FIG. 3, a snap ring 36 is fitted on the outer periphery of the end surface portion of the photosensitive drum 16 of the driven shaft 32, and between the coupling member 34 and the snap ring 36 on the outer periphery of the driven shaft 32. A spring 37 is mounted on the front side. Therefore, the coupling member 34 is always urged by the spring 37 in the tip direction of the drive shaft 31 (the direction in which the fitting protrusion 34b of the coupling member 34 is fitted in the fitting groove 31b of the drive shaft 31). In the state shown in FIG. 3 before the drive shaft 31 and the driven shaft 32 are connected, the coupling member 34 is stationary at a position where the pin 35 abuts against the bottom of the engagement groove 34a.

  Thus, in the rotation transmission device 30 according to the present embodiment, the drive shaft 31 and the driven shaft can be obtained by inserting the tip end portion of the driven shaft 32 into the fitting hole 31a of the drive shaft 31 as shown in FIG. 32 is coaxially arranged so that both are centered. If the driven shaft 32 is further pushed into the drive shaft 31 side together with the photosensitive drum 16 in this state, when the fitting protrusion 34b of the coupling member 34 and the fitting groove 31b of the drive shaft 31 do not match, FIG. ) And FIG. 6A, the fitting protrusion 34b of the coupling member 34 and the fitting groove 31b of the drive shaft 31 are not fitted, and both end surfaces abut against each other, and the coupling member 34 is a spring. It slides on the driven shaft 32 in the direction indicated by the arrow (right direction) against the urging force of 37.

  When the driven shaft 32 is rotated in any direction together with the photosensitive drum 16 from the above state, the fitting protrusion 34b of the coupling member 34 and the fitting groove 31b of the drive shaft 31 are aligned as shown in FIG. Since the coupling member 34 slides in the direction of the drive shaft 31 due to the biasing force of the spring 37, the fitting protrusion 34b of the coupling member 34 is connected to the drive shaft as shown in FIGS. 5 (c) and 6 (c). The drive shaft 31 and the driven shaft 32 are connected via a coupling member 34, and rotation from a drive source (not shown) is driven from the drive shaft 31 via the coupling member 34. The driven shaft 32 and the photosensitive drum 16 bound to the driven shaft 32 are rotated at a predetermined speed.

  By the way, in the present embodiment, the degree of fitting between the coupling member 34 and the driven shaft 32 is changed before and after the concave / convex fitting of the coupling member 34 to the drive shaft 31, and after the concave / convex fitting of the coupling member 34. The degree of fitting of the coupling member 34 is as tight as possible as long as the coupling member 34 is slidable, and the degree of fitting of the coupling member 34 before fitting the concave and convex portions is made looser than the degree of fitting after fitting. Features.

  Specifically, as shown in FIG. 5, the outer diameter of the distal end portion of the driven shaft 32 is set smaller than the inner diameter of the coupling member 34, and the large diameter portion 32 a is provided around a part of the outer periphery. It is integrally formed. Here, the outer diameter of the large-diameter portion 32 a is set slightly smaller than the inner diameter of the coupling member 34, and this large-diameter portion 32 a allows the coupling member 34 to slide on the inner periphery of the coupling member 34. Fit to the nectar to the extent you want.

  Thus, as shown in FIG. 5A, when the coupling member 34 is not in contact with the end surface of the drive shaft 31, the coupling member 34 is urged toward the drive shaft 31 by the spring 37, and The pin 35 is stationary in a state where the pin 35 is engaged with the bottom of the engaging groove 34a (the state shown in FIG. 3). At this time, the large-diameter portion 32a of the driven shaft 32 is fitted to the inner periphery of the coupling member 34, and the degree of fitting of the coupling member 34 with respect to the driven shaft 32 is determined by the coupling member 34. 32 is set as tight as possible as long as it can slide on.

  When the driven shaft 32 is pushed together with the photosensitive drum 16 toward the drive shaft 31 from the state shown in FIG. 5A, the fitting protrusion 34b of the coupling member 34 and the fitting groove 31b of the drive shaft 31 are formed. 5 (b) and FIG. 6 (a), the fitting protrusion 34b of the coupling member 34 and the fitting groove 31b of the drive shaft 31 do not fit with each other, as shown in FIGS. The coupling member 34 slides on the driven shaft 32 in the illustrated arrow direction (right direction) against the urging force of the spring 37. When the coupling member 34 slides on the driven shaft 32 in this manner, the fitting between the inner periphery of the coupling member 34 and the large diameter portion 32a of the driven shaft 32 is released, and the fitting protrusion 34b of the coupling member 34 is removed. In the state before being fitted into the fitting groove 31 b of the drive shaft 31, the outer periphery of the driven shaft 32 other than the large diameter portion 32 a is fitted to the inner circumference of the coupling member 34. Accordingly, in this state, the coupling member 34 is loosely fitted, and the coupling member 34 can be smoothly slid on the driven shaft 32.

  Next, when the driven shaft 32 is rotated in any direction together with the photosensitive drum 16 from the above state, the fitting protrusion 34b of the coupling member 34 and the fitting groove 31b of the drive shaft 31 are shown in FIG. 6B. And the coupling member 34 slides in the direction of the drive shaft 31 (leftward in FIG. 6B) by the biasing force of the spring 37, and the coupling member 34 is fitted as shown in FIG. 5C. The mating protrusion 34 b is fitted in the fitting groove 31 b of the drive shaft 31. At this time, the large-diameter portion 32 a of the driven shaft 32 is fitted again to the inner periphery of the coupling member 34, and the degree of fitting of the coupling member 34 to the driven shaft 32 is determined by the coupling member 34. In the state shown in FIG. 5C and FIG. 6C in which the drive shaft 31 and the driven shaft 32 are connected via the coupling member 34, as far as possible as far as possible is slidable. As a result, rattling of the coupling member 34 is suppressed, and highly accurate rotation transmission to the photosensitive drum 16 becomes possible.

  In the laser printer 1 shown in FIG. 1, the rotation transmission device 30 provided in the laser printer 1 smoothly and surely connects and disconnects the rotation between the drive shaft 31 and the driven shaft 32, and the coupling member 34. Since rattling is suppressed and high-accuracy rotation transmission to the photosensitive drum 16 is possible, the photosensitive drum 16 can be attached and detached smoothly and reliably, and high-quality images can be obtained by suppressing rotational vibration of the photosensitive drum 16. It can be obtained stably.

<Embodiment 2>
Next, a power transmission device according to a second embodiment of the present invention will be described with reference to FIGS.

  7 is an exploded perspective view of a rotation transmission device according to Embodiment 2 of the present invention, FIG. 8 is a side sectional view of a driven shaft of the rotation transmission device, and FIGS. 9A to 9C are views of the rotation transmission device. It is a plane sectional view showing a connection procedure, and in these figures, the same numerals are given to the same element as what was shown in Drawing 2-Drawing 6, and the explanation about them again is omitted below.

  In the present embodiment, as shown in FIGS. 7 to 9, the outer diameter of the distal end portion 32A from the distal end of the driven shaft 32 to the sliding range of the coupling member 34 is constant and is larger than the outer diameters of the other portions 32B. It is characterized by a large setting. Here, the outer diameter of the tip portion 32A having a large diameter of the driven shaft 32 is set slightly smaller than the inner diameter of the fitting hole 31a of the drive shaft 31 and the coupling member 34, and has a diameter other than the tip portion 32A of the driven shaft 32. The outer diameter of the small portion 32B is set smaller than the inner diameter of the coupling member 34.

  Accordingly, the tip end portion 32A of the driven shaft 32 is fitted into the fitting hole 31a of the drive shaft 31 and the state shown in FIG. 9A before the coupling member 34 abuts against the end surface of the drive shaft 31. In the state shown in FIG. 9C after the fitting protrusion 34 b of the coupling member 34 is fitted in the fitting groove 31 b of the drive shaft 31, the tip end portion 32 </ b> A of the driven shaft 32 is formed on the inner periphery of the coupling member 34. The degree of fitting of the coupling member 34 with respect to the driven shaft 32 is set as tight as possible to the extent that the coupling member 34 can slide on the driven shaft 32.

  Thus, also in the present embodiment, the degree of fitting of the coupling member 34 and the driven shaft 32 is changed before and after the concave / convex fitting of the coupling member 34 to the drive shaft 31, and the concave / convex of the coupling member 34. The degree of fitting after fitting is as tight as possible as long as the coupling member 34 is slidable, and the degree of fitting of the coupling member 34 before the concave-convex fitting is less than the degree of fitting after fitting. is doing.

  That is, as shown in FIG. 9A, when the coupling member 34 is not in contact with the end face of the drive shaft 31, the coupling member 34 is urged toward the drive shaft by the spring 37, and the engagement groove thereof. The pin 35 is stationary with the pin 35 engaged with the bottom of the pin 34a (the state shown in FIG. 8). At this time, the leading end portion 32A having a large diameter of the driven shaft 32 is fitted in the inner periphery of the coupling member 34, and therefore, the degree of fitting of the coupling member 34 to the driven shaft 32 is determined according to the coupling member. 34 is as tight as possible as long as it can slide on the driven shaft 32.

  If the driven shaft 32 is pushed together with the photosensitive drum 16 from the above state to the drive shaft 31 side, when the fitting protrusion 34b of the coupling member 34 and the fitting groove 31b of the drive shaft 31 do not coincide with each other, FIG. As shown in FIG. 3, the fitting protrusion 34b of the coupling member 34 and the fitting groove 31b of the drive shaft 31 do not fit together, and both end surfaces come into contact with each other, and the coupling member 34 resists the biasing force of the spring 37. Then, it slides on the driven shaft 32 in the direction indicated by the arrow (right direction). When the coupling member 34 slides on the driven shaft 32 in this manner, the fitting between the inner periphery of the coupling member 34 and the distal end portion 32A having a large diameter of the driven shaft 32 is disengaged, and the coupling member 34 is fitted. In a state before the protrusion 34 b is fitted in the fitting groove 31 b of the drive shaft 31, the outer periphery of the small diameter portion 32 </ b> B other than the tip portion 32 </ b> A of the driven shaft 32 is fitted to the inner periphery of the coupling member 34. Accordingly, in this state, the coupling member 34 can swing with respect to the driven shaft 32, and the coupling member 34 can be smoothly engaged with the driven shaft 32.

  Next, when the driven shaft 32 is rotated in any direction together with the photosensitive drum 16 from the above state, the fitting protrusion 34b of the coupling member 34 and the fitting groove 31b of the drive shaft 31 are matched, and the coupling member 34 is aligned. Is slid in the direction of the drive shaft 31 (in the direction of the arrow in the figure) by the biasing force of the spring 37, and the fitting protrusion 34b of the coupling member 34 is fitted in the fitting groove 31b of the drive shaft 31 as shown in FIG. Match. At this time, the tip end portion 32A having a large diameter of the driven shaft 32 is re-fitted to the inner periphery of the coupling member 34, and the degree of fitting of the coupling member 34 to the driven shaft 32 is determined by the coupling member 34 being driven. In the state shown in FIG. 9C in which the drive shaft 31 and the driven shaft 32 are coupled via the coupling member 34, the coupling member is as tight as possible as long as it can slide on the shaft 32. 34 is suppressed, and highly accurate rotation transmission to the photosensitive drum 16 becomes possible.

  As described above, also in the present embodiment, the same effect as in the first embodiment can be obtained.

  Although the present invention has been described with respect to a mode in which the present invention is applied to a laser printer and a rotation transmission mechanism that connects and disconnects rotation transmission to the photosensitive drum, the present invention is provided with any other image forming apparatus and the same. Of course, the present invention can be similarly applied to any rotation transmission mechanism that connects and disconnects rotation transmission to any given process equipment.

1 Laser printer (image forming device)
2 Printer body (image forming device body)
DESCRIPTION OF SYMBOLS 3 Paper discharge tray 4 Manual feed tray 5 Manual feed roller 6 Manual paper feed part 7 Cassette paper feed part 8 Image forming part 9 Fixing device 10 Paper discharge part 11 Paper feed cassette 12 Pick roller 13 Feed roller 14 Retard roller 15 Registration roller 16 Photosensitive drum (image carrier)
17 Charging Device 18 Developing Device 19 Transfer Roller 20 Cleaning Device 21 Laser Scanner Unit (LSU)
22 toner hopper 23 fixing roller 24 pressure roller 25 discharge roller pair 26 guide rib 30 rotation transmission device 31 drive shaft (second shaft)
31a Drive shaft fitting hole 31b Drive shaft fitting groove 32 Driven shaft (first shaft)
32A Tip portion of driven shaft 32B Portions other than tip portion of driven shaft 32a Large diameter portion of driven shaft 33 Drum gear 34 Coupling member 34A Convex portion of coupling member 34a Engaging groove of coupling member 34b Coupling of coupling member Projection 35 Pin 36 Snap ring 37 Spring L Conveyance path P Paper

Claims (4)

A coupling member is fitted on the outer periphery of the first shaft of the first and second shafts arranged coaxially so as to be slidable in the axial direction and non-rotatable in the circumferential direction, and the end shaft of the second shaft The tip end portion of the first shaft is fitted into a fitting hole formed in the center, and the coupling member is concavo-convexly fitted to the second shaft, and the coupling member is urged in the fitting direction. In the rotation transmission device that performs rotation transmission between the first shaft and the second shaft,
The degree of fitting between the coupling member and the first shaft is changed before and after the concave / convex fitting of the coupling member to the second shaft, and the degree of fitting of the coupling member after the concave / convex fitting is changed. A rotation transmission device characterized in that the coupling member is tightened as much as possible and the fitting degree before the fitting of the coupling member is made looser than the fitting degree after fitting. The rotation transmission device according to claim 1, wherein a large diameter portion is formed in a part of the first shaft in a sliding range of the coupling member.   2. The rotation transmission device according to claim 1, wherein an outer diameter from a tip of the first shaft to a sliding range of the coupling member is constant and set larger than an outer diameter of another portion. The latent image formed on the rotationally driven image carrier is developed as a toner image with toner, the toner image is transferred onto a recording material, and then recorded through an electrophotographic process for fixing the toner image on the recording material. In an image forming apparatus for forming an image on a material,
An image forming apparatus comprising the rotation transmission device according to claim 1 in a drive transmission path from a drive source to the image carrier.

Images