JP4227488B2 - Drive transmission device and image forming apparatus - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive transmission device for transmitting a driving force to a unit that can be attached to and detached from an apparatus main body, and an image forming apparatus provided with the drive transmission device. The present invention relates to an image forming apparatus capable of preventing density unevenness and a drive transmission device used therefor.

  In recent years, the demand for color electrophotographic image forming apparatuses capable of forming color images has increased, (1) low running cost, (2) small space, (3) low power, (4) high image quality, It is expected to introduce a color image forming apparatus that can achieve six items of (5) high speed and (6) improved operability.

  Among them, (6) while simplifying operability, (5) high speed, and (4) tandem or 4 drums as a technology to provide high quality color images There is a color image forming apparatus of the type. This is a system that uses four color process cartridges of yellow, magenta, cyan, and black in a color image forming apparatus to form an image by arranging four photosensitive drums in parallel to improve operability and increase the speed. It is.

  Further, from the viewpoint of the above (6) improvement in operability, the electrophotographic photosensitive member, the charging means, the developing means, the cleaning means, etc. are integrated into a cartridge, and this cartridge can be attached to and detached from the main body of the image forming apparatus. A process cartridge system is adopted. The operability is further improved by this cartridge system, and the user can easily perform maintenance of the process means. Similarly, the intermediate transfer member of the main body of the image forming apparatus has a unit configuration and is detachable from the main body of the image forming apparatus, thereby improving operability and maintainability.

JP 2003-167411 A

  However, in the above-described conventional configuration, four color images are formed independently and one color image is formed on the intermediate transfer member. Therefore, the image formation points formed on each drum are intermediate transfer images. There is a problem that it is easily displaced from a target (ideal) position when transferred onto the body. In addition, since the four color process cartridges and the intermediate transfer unit are detachable from the image forming apparatus main body in consideration of operability, the configuration of the image forming apparatus main body has become complicated. There was a problem that accuracy and rotation accuracy during drive transmission deteriorated.

  In particular, the position accuracy of the photosensitive drum and the intermediate transfer belt in the intermediate transfer body unit and the rotational accuracy during drive transmission in each of the four color process cartridges are not varied in order to achieve high accuracy and high image quality. Although stable and high accuracy is required, both are configured to be detachable from the main body of the image forming apparatus. Therefore, the number of parts interposed therebetween has increased and the drive connection configuration has become complicated. The accuracy and rotational accuracy during drive transmission tend to deteriorate.

  When the process cartridge including the photosensitive drum in contact with the intermediate transfer belt is detached from the image forming apparatus main body in the drum axial direction, it is necessary to once separate the entire intermediate transfer unit from the photosensitive drum. The image forming apparatus having the configuration has a contact / separation mechanism for the intermediate transfer unit as shown in FIG.

  At this time, in order to achieve both the contact / separation function of the intermediate transfer body unit and the detachable structure from the main body, as shown in FIG. 14, the drive coupling provided in the main body drive unit for driving the intermediate transfer body unit It is necessary for 500 to retreat from the drive transmission position by performing a thrust movement in the axial direction of the fitted main body drive shaft 501 and to release the drive connection to the intermediate transfer body unit.

To the drive coupling 500 to allow thrust moving on body drive shaft, the drive coupling 500 inside diameter portion and the minimum of the fitting backlash outside diameter portion of the main assembly driving shaft 501 (in FIG. 14 A gap D) is required. For this reason, when a load fluctuation or the like occurs in the intermediate transfer member and the photosensitive drum, the above-described fitting backlash D causes rotation unevenness between the drive coupling 500 and the main body drive shaft 501, thereby transporting the intermediate transfer unit. There is a possibility of inducing speed unevenness in the speed.

  Then, in the state where the transfer speed of the intermediate transfer belt is uneven, the toner image formed on the photosensitive drum of each color shifts the transfer position to the intermediate transfer belt for each color, causing color shift, In addition, there is a problem that even in the same color, transferability is uneven and density unevenness is caused.

  SUMMARY OF THE INVENTION The present invention solves the above-described problems, and an object of the present invention is to improve the operability of the detachable unit and drive transmission without rotational blur and a high-quality image using the same. An image forming apparatus capable of forming images is provided.

The first means in the present invention includes a drive shaft and a drive coupling supported so as to be movable in the axial direction on the drive shaft, and the drive coupling is detachable from the apparatus main body. Engage with the driven coupling provided in the unit to transmit the drive, and the engaging portion between the drive coupling and the driven coupling generates a retraction force when transmitting the drive. In the drive transmission device provided with the pull-in force generating means , the drive shaft is provided with a shaft taper portion, and an inner diameter portion of the drive coupling is provided with a coupling taper portion that can be engaged with the shaft taper portion, thereby transmitting the drive. Sometimes, the shaft taper portion and the coupling taper portion come into contact with each other by the pulling force of the pulling force generating means, and the drive coupling is in contact with the drive shaft. While being positioned in the axial direction, the driving center of the drive coupling and the drive shaft, characterized in that it is alignment.

The second means includes an image carrier and an intermediate transfer member to which the toner image formed on the image carrier is transferred, and the toner image transferred to the intermediate transfer member is transferred to a recording medium. 2. The image forming apparatus according to claim 1, wherein the intermediate transfer member is configured as a unit that can be attached to and detached from the apparatus main body, and the drive transmission device according to claim 1 transmits a driving force to the unit. To do.

In the first means, a rotational force is transmitted to the driving coupling on the main body side by adopting a configuration in which a pulling force is generated by engagement of the driving coupling on the main body side and the driven coupling of the unit. During this, a thrust force is always generated on the driven coupling side of the unit. In order for the drive coupling to move in a thrust manner on the main body drive shaft, the drive coupling and the main body drive shaft need a minimum required backlash (gap), but the main body drive shaft is provided with a tapered portion. By providing a similar taper portion on the inner diameter portion of the drive coupling to be engaged with each other and engaging each other, the drive coupling is positioned in the thrust direction by the taper portion, and the drive coupling The drive center of the drive center and the drive center of the main body drive shaft are automatically aligned, and it is possible to prevent the above-described drive unevenness due to the fitting play during rotation transmission.

Accordingly, in the image forming apparatus that transmits the drive to the unit using the drive transmission device such as the first means , for example, it is possible to prevent the occurrence of speed unevenness in the intermediate transfer member or the like. Improves the problem that the toner image that has been created shifts the transfer position to the intermediate transfer body for each color and causes color misregistration, and unevenness in transferability within the same color causes density unevenness. A high-quality color image can be provided.

  Next, an image forming apparatus including a drive transmission device according to an embodiment of the present invention will be described with reference to the drawings.

[First Embodiment]
[Overall Description of Image Forming Apparatus]
First, a general image forming operation of the overall configuration of the color image forming apparatus will be schematically described with reference to FIG.

  FIG. 1 is an explanatory diagram of the overall configuration of a laser printer which is an embodiment of a color image forming apparatus.

  As shown in FIG. 1, the color laser printer includes a photosensitive drum 1 as an image carrier that rotates at a constant speed for each color of yellow (Y), magenta (M), cyan (C), and black (K). The image forming unit includes a color developing unit, and an intermediate transfer member 9 that holds the color image developed and transferred by the image forming unit and further transfers it to the transfer material 2 fed from the feeding unit. The transfer material 2 to which the color image has been transferred is then conveyed to the fixing unit 17 to fix the color image on the transfer material 2 and discharged to a discharge unit 23 on the upper surface of the apparatus by a discharge roller. The four color developing devices are individually detachable from the printer body.

  Next, the configuration of each part of the image forming apparatus will be sequentially described in detail.

[Photosensitive drum]
A photosensitive drum 1 (1Y, 1M, 1C, 1K), which is a drum-shaped electrophotographic photosensitive member as an image carrier, is integrally formed as a process cartridge 3 (3Y, 3M, 3C, 3K) together with a developing device and a charging unit. The developing unit 4 (4Y, 4M, 4C, 4K) is configured to be detachably supported with respect to the printer body, and can be easily replaced in accordance with the life of the photosensitive drum 1. The photosensitive drum 1 according to this embodiment is configured by coating an organic photoconductor layer on the outside of an aluminum cylinder, and is rotatably supported by a frame of the process cartridge 3 of the photosensitive drum 1. Further, the driving force of a driving motor (not shown) is transmitted to one end on the rear side in the drawing, whereby the photosensitive drum 1 is rotated in the counterclockwise direction shown in the drawing according to the image forming operation.

[Charging means]
The charging means 5 (5Y, 5M, 5C, 5K) uses an injection charging method, and uniformly charges the surface of the photosensitive drum 1 with a charging agent applied voltage via a charging agent.

[Exposure means]
The exposure to the photosensitive drum 1 is performed from the scanner unit 6 (6Y, 6M, 6C, 6K). That is, when an image signal is applied to the laser diode, the laser diode irradiates the polygon mirror 6a (6Ya, 6Ma, 6Ca, 6Ka) with image light corresponding to the image signal. The polygon mirror 6a is rotated at a high speed by a scanner motor, and the surface of the photosensitive drum 1 on which the image light reflected by the polygon mirror 6a rotates at a constant speed via the imaging lens 6b (6Yb, 6Mb, 6Cb, 6Kb) is selected. Exposure, and as a result, an electrostatic latent image is formed on the photosensitive drum 1.

[Development means]
The developing means is composed of four developing units 4 that can develop each color of yellow, magenta, cyan, and black in order to visualize the electrostatic latent image. In each of the four color developing devices 4, sleeves 3S (3YS, 3MS, 3CS, and 3KS) are arranged at a position facing the corresponding photosensitive drum 1 with a minute interval from the photosensitive drum 1, and each color toner is placed on the photosensitive drum 1. To form a visible image.

  Each color developer 4 feeds the toner in the container by a feeding mechanism, and on the outer periphery of the sleeve 3S, the powder in which the toner (non-magnetic) and the developer (magnetic) are mixed on the outer periphery of the sleeve 3S is rotated clockwise in the figure. Coat. Thereafter, the toner in the powder is developed with toner corresponding to the electrostatic latent image on the photosensitive drum 1.

[Intermediate transfer member]
The intermediate transfer member 9 rotates in the clockwise direction in synchronization with the outer peripheral speed of the photosensitive drum 1 in order to multiplex-transfer the toner images visualized by the developing units 4 during the color image forming operation. In addition, the intermediate transfer member 9 that has undergone multiple transfer sandwiches and conveys the transfer material 2 by a secondary transfer roller 10 to which a voltage is applied, thereby simultaneously transferring multiple color toner images on the intermediate transfer member to the transfer material 2.

  The intermediate transfer member 9 according to the present embodiment is formed of a resin belt having a circumferential length of about 1000 mm. The intermediate transfer member 9 is stretched around three axes of a driving roller 9a, a secondary transfer counter roller 9b, and a tension roller 9c, and both ends of the tension roller 9c. Even if the peripheral length of the intermediate transfer body 9 changes due to temperature and humidity in the main body and changes with time, the amount of change can be absorbed. The intermediate transfer member 9 is supported on the main body with a driving roller as a fulcrum, and the driving force of a driving motor (not shown) is transmitted to the driving roller at one end on the rear side of the drawing, whereby the intermediate transfer member 9 is shown in FIG. It is made to rotate in the turning direction. Further, the intermediate transfer body 9 is configured as an intermediate transfer body unit 90 together with the driving roller 9a, the tension roller 9c and the like, and the intermediate transfer body unit 90 can be easily attached to and detached from the apparatus main body in the front of FIG. It can be done.

[Transfer material transport section]
The feeding unit feeds the transfer material 2 to the image forming unit, and includes a cassette 7 containing a plurality of transfer materials 2, a feed roller 8a, a feed roller 8b, a double feed preventing retard roller 8c, and a feed. It is mainly composed of a guide 8d and a registration roller 8e. At the time of image formation, the feeding roller 8a is driven and rotated in accordance with the image forming operation to separate and feed the transfer material 2 in the cassette 7 one by one, and is guided by the guide plate 8d, and the registration roller via the conveying roller. 8e. During the image forming operation, the registration roller 8e performs a non-rotating operation for causing the transfer material 2 to stand still and a rotating operation for transporting the transfer material 2 toward the intermediate transfer member in a predetermined sequence. The image at the process and the transfer material 2 are aligned.

  Further, the transfer material 2 on which the toner image has been transferred and fixed is discharged to the discharge portion 23 by the discharge rollers 20, 21 and 22.

[Transfer section]
In a primary transfer portion that transfers a toner image from the photosensitive drum 1 to the intermediate transfer member 9, a primary transfer roller 71 (71Y, 71M, 71C, 71K) is passed through the intermediate transfer member 9 by an urging force (not shown). Pressurized in the direction of the drum 1, a nip portion is formed by both of them, and the toner image on the photosensitive drum 1 is primarily transferred to the intermediate transfer member 9 at a position T1 (T1Y, T1M, T1C, T1K) in the drawing. .

  On the other hand, the secondary transfer portion that transfers the toner image from the intermediate transfer member 9 to the transfer material 2 is composed of a swingable transfer roller 10. The transfer roller 10 has a metal shaft wound with a medium resistance foamed elastic body, is movable up and down in the drawing, and has a drive. While the four color toner images are formed on the intermediate transfer member 9, that is, until the toner image on the intermediate transfer member 9 reaches the secondary transfer portion, transfer is performed as shown by the dotted line in the figure so as not to disturb the image. The roller 10 is positioned below and is separated from the intermediate transfer member 9.

  Thereafter, in accordance with the timing of transferring the color image to the transfer material 2, the transfer roller 10 is moved to a position T2 by a cam member (not shown) at an upper position indicated by a solid line in the drawing, that is, to the intermediate transfer body 9 via the transfer material 2. Pressed with pressure. At this time, a bias is simultaneously applied to the transfer roller 10, and the toner image on the intermediate transfer body 9 is transferred to the transfer material 2. Here, since the intermediate transfer member 9 and the transfer roller 10 are respectively driven, the transfer material 2 sandwiched between the two is conveyed at a predetermined speed in the left direction in the figure at the same time as the transfer step is performed, and the next step. It is sent to the fixing device.

[Intermediate transfer member cleaning section]
The intermediate transfer body cleaning unit 14 includes a cleaning blade 12a, a pressure spring for pressing the cleaning blade 12a against the intermediate transfer body 9, a fur brush 13, and a cleaner container 14a for holding them.

  The fur brush 13 is formed of rayon yarn, and neutralizes the toner image that has not been transferred on the intermediate transfer body after the secondary transfer. The fur brush 13 is rotated at a constant peripheral speed in the reverse direction (clockwise direction) with respect to the intermediate transfer member 9 by transmitting a driving force of a driving motor (not shown) to one end on the front side in the drawing. Note that a tension roller 9c is disposed as a backup roller at the opposite portion of the fur brush 13.

  The material of the cleaning blade 12a is urethane rubber, which is affixed to the metal plate 12b and is pressed against the intermediate transfer body 9 at a predetermined angle by the pressure spring 12e with the shaft 12d held in the cleaner container 14a as the rotation center. Uniform contact with the intermediate transfer member 9 is possible. Note that a tension roller 9c is disposed as a backup roller at the opposite portion of the cleaning blade 12a so that the cleaning blade 12a can contact the intermediate transfer member 9 with a predetermined contact pressure. The toner image neutralized by the fur brush 13 at the point of contact of the cleaning blade 12a is scraped off from the intermediate transfer member 9 and the intermediate transfer member 9 is cleaned.

[Fixing part]
The fixing unit 17 fixes the toner image formed on the transfer material 2 via the intermediate transfer member 9 with the toner image formed by the developing means, and heat is applied to the transfer material 2 as shown in FIG. It comprises a fixing roller 18 for adding and a pressure roller 19 for pressing the transfer material 2 against the fixing roller 18. Each roller is a hollow roller and has a heater (not shown) inside, and is rotated and simultaneously transferred. It is comprised so that the material 2 may be conveyed. In other words, the transfer material 2 holding the toner image is conveyed by the fixing roller 18 and the pressure roller 19, and the toner is fixed to the transfer material 2 by applying heat and pressure.

[Image forming operation]
Next, an operation when image formation is performed by the apparatus configured as described above will be described.

  First, the feeding roller 8a shown in FIG. 1 is rotated to separate one transfer material 2 in the feeding cassette 1, and is conveyed to the registration roller 8e. On the other hand, the photosensitive drum 1 and the intermediate transfer member 9 each rotate at a predetermined outer peripheral speed V in the direction indicated by the arrow.

  As shown in FIG. 2, when an arbitrary point on the outer periphery of the intermediate transfer member reaches the position S in the figure, the photosensitive drum 1 whose surface is uniformly charged by the charging means is subjected to laser exposure at the position E in the figure. Perform image formation. The distance a from the exposure position E on the circumferential surface of the photosensitive drum 1 to the contact portion T1 with the intermediate transfer member 9 and the distance b from the illustrated point S to T1 of the intermediate transfer member 9 are respectively the photosensitive drum. 1 and the intermediate transfer member 9 correspond to the distance traveled during a predetermined time t. Therefore, after the elapse of time t, the point E at the beginning of image writing coincides with the point S on the intermediate transfer member 9 at the position T1. That is, the image is formed in the counterclockwise direction with respect to the intermediate transfer member 9 with the point S as the tip.

  The scanner unit 6Y irradiates the yellow image with a laser, forms a yellow latent image on the photosensitive drum 1Y, and develops it with the developing device 4Y to form a yellow toner image. The toner image is applied to the intermediate transfer member 9. Primary transcription. Similarly, the color toner images of magenta M, cyan C, and black K are superimposed and transferred to the intermediate transfer member 9 to form a color image, which is collectively transferred to the transfer material 2 conveyed in the secondary transfer portion. A full color image is formed.

  The transfer material 2 that has passed through the secondary transfer portion is peeled off from the intermediate transfer member 9, transported to the fixing portion 17, and after toner fixing, the image is transferred onto the discharge tray 23 at the top of the main body via the discharge roller pair 20, 21, 22. The sheet is discharged with the surface facing downward, and the image forming operation is completed.

[Drive transmission device]
Next, the configuration of the drive transmission device for transmitting the drive from the image forming apparatus main body to the unit, which is a feature of the present embodiment, will be described.

  First, FIGS. 3 to 7 show the main body structure around the intermediate transfer body unit in which the intermediate transfer body 9 is separated from the photosensitive drum 1, and the drive transmission structure will be described using this.

  FIG. 3 is an explanatory view showing a state of a drive connecting portion between the intermediate transfer body unit 90 and the image forming apparatus main body. Inside the main body of the image forming apparatus, a guide rail portion (not shown) for attaching / detaching the intermediate transfer body unit 90 is provided inside the front and rear side plates along the horizontal direction of the main body. Install 90 in the body.

  Further, on the back side of the image forming apparatus main body, a drive unit for driving the plurality of photosensitive drums 1 and the intermediate transfer body unit 90 is positioned and fixed outside the frame (main body rear side plate) on the back side of the image forming apparatus main body. Has been.

  FIG. 4 is an explanatory view showing the function of the intermediate transfer body unit 90 contacting and separating from the photosensitive drum 1. The contact / separation function is constituted by the eccentric cams 210 and 216 and the eccentric cam shaft 209. The eccentric cams 210 and 216 are rotatably held around the eccentric cam shaft 209, and are configured to perform the same rotational operation by a link mechanism (not shown). When the user rotates a contact / separation lever (not shown) after the process cartridge 3 and the intermediate transfer body unit 90 are mounted on the image forming apparatus main body, the eccentric cams 210 and 216 are rotated 180 degrees by the link mechanism described above, and the frame The eccentric cam receiving portion 205a provided at 129 (see FIG. 5) is pushed up (see FIG. 8), and the intermediate transfer body unit 90 is lifted substantially in parallel to come into contact with the photosensitive drum 1 and drive-coupled. It has become.

  FIG. 5 and FIG. 6 are explanatory diagrams of the drive connection configuration of the drive unit 103 and the intermediate transfer body unit 90. FIG.

  As shown in FIG. 6, the drive unit 103 drives the drive units 103Y, 103M, 103C, and 103K that drive the photosensitive drums 1 of yellow, magenta, cyan, and black, and the intermediate transfer member 9 on the drive frame 104. Each drive unit 103ITB is positioned and fixed with high accuracy. Further, a drum motor 45 fixed to each drive unit for each color, a pinion 46 fixed to the motor shaft of the motor 45, and an intermediate gear that meshes with the pinion 46 and the large gear 48 and is rotatably supported. 47, a large gear 48, a drum drive shaft 49 fixed to the large gear 48 and having a substantially spherical positioning portion 57 formed at the tip thereof, a bearing 51 for supporting the drum drive shaft 49, and a triangular coupling 52 and a return spring 62 that urges the triangular coupling 52 in the process cartridge direction (the right direction in FIG. 6B). The bearing 51 supports the drum drive shaft 49 so as not to move in the axial direction.

  Further, as shown in FIG. 5, the intermediate transfer body unit driving unit 103ITB includes a fixed motor 45, a pinion 120 fixed to the motor shaft, and an intermediate gear that meshes with the pinion 120 and the large gear 122 and is rotatably supported. 121, a large gear 122, a drive shaft 125 fixed to the large gear 122, a bearing 51 that supports the drive shaft 125, and a drive coupling 124. The bearing 51 supports the drive shaft 125 so as not to move in the axial direction.

Further, as shown in FIG. 5, the drive coupling 124 is supported in the coupling holder 123 so as to be movable in the thrust direction (axial direction of the drive shaft) along the drive shaft 125, and is intermediately transferred by the return spring 126. It is biased in the body direction (left direction in FIG. 5). Further, a convex portion 210a is provided on the side surface of the eccentric cam 210, and in the separated state shown in FIG. 5, the convex portion 210a is separated from the connection release lever 130 that is rotatably supported. The lever 130 is rotated in the clockwise direction by the release spring 200 in the drawing having a stronger urging force than the return spring 126, holds the drive coupling 124 in the retracted position, and the drive connection is completely released.

  Further, as shown in FIG. 6A, the positioning pins 105a and 105b are fixed at two locations on the opposite side of the gear portion on the drive frame 104, and their positions are coaxial with the central axis of the photosensitive drum 1 of each color. Above (y = 0). Further, as shown in FIG. 6C, the black side positioning pin (first reference axis) 105a is also a reference in the x direction in the driving frame 104 (x = 0), and the driving unit 103 has the positioning pin (first reference axis). (1 reference shaft) 105a is fixed to the rear plate of the main body by screws or the like. The drum driving shaft 49 and the intermediate transfer member positioning unit 131 for driving the photosensitive drums 1 of the respective colors are both in the x direction (horizontal direction) and the y direction (vertical direction) with reference to the positioning pin (first reference axis) 105a. The drive unit 103 is mounted with high accuracy and is fixed to the rear plate of the main body with reference to the positioning pin (first reference shaft) 105a, so that the user performs the contact operation of the intermediate transfer body unit 90 described above. In this case, the positioning fitting member 132 provided on the intermediate transfer body frame 129 is accurately fitted between the two intermediate transfer body positioning portions 131 on the drive frame 104 (see FIG. 10), and the intermediate transfer body unit 90 Is positioned accurately with reference to the positioning pin (first reference axis) 105a. At this time, the intermediate transfer member drive shaft 125 is accurately installed in the x direction on the drive frame 104 with reference to the intermediate transfer member positioning portion 131, and the positioning fitting member 132 is fitted between the intermediate transfer member positioning portions 131. When the intermediate transfer body 9 is positioned together, a dimensional error in the horizontal direction (x direction) between the drive shaft 125 and the central axis of the drive roller shaft 128 of the intermediate transfer body unit 90 is caused by the coupling between the two couplings. It can be minimized.

  FIG. 7 is an explanatory view showing details of the drive connecting portion of the intermediate transfer body unit 90 in the separated state. The drive coupling 124 is thrustly moved on the intermediate transfer body drive shaft 125 in the right direction (main body side) in FIG. 7 against the urging force of the return spring 126 by the connection release lever 130 shown in FIG. The state is retracted from the transmission position. The intermediate transfer body drive shaft 125 is provided with a shaft taper portion 152b. At the same time, a coupling taper portion 152a having the same angle is formed on the inner diameter portion of the drive coupling 124 fitted therewith.

  In addition, a minimum required backlash (gap) is provided between the inner diameter of the drive coupling 124 and the outer diameter of the intermediate transfer member drive shaft 125 so that the drive coupling 124 can be smoothly transferred to the intermediate transfer member. It is configured to be able to perform a thrust movement on the drive shaft 125. Further, a D-cut portion is provided at the inner diameter portion of the drive coupling 124 and the outer diameter tip portion of the intermediate transfer member drive shaft 125, and the driving force is transmitted to the intermediate transfer member 9 by engaging both.

  Next, FIGS. 8 to 11 are views showing the main body structure around the intermediate transfer body unit when the intermediate transfer body 9 is in contact with the photosensitive drum 1, and the drive transmission structure will be described with reference to this. To do.

  As shown in FIG. 8, when the user rotates the separation lever (not shown) to bring the intermediate transfer unit 9 into contact with the photosensitive drum 1, the convex shape of the eccentric cam 210 is shown in FIG. The receiving part of the connection release lever 130 on which the part 210a is rotatably supported is pushed, and the connection release lever 130 is rotated counterclockwise by overcoming the urging force of the release spring 200 in the drawing. As a result, the drive coupling 124 is released from the restraining force of the connection release lever 130, and is slid along the drive shaft 125 in the direction of the intermediate transfer body unit (left direction in FIG. 9) by the urging force from the return spring 126. It is connected to the driven coupling 127 of the body unit 90. At the same time, as shown in FIG. 10, the positioning fitting member 132 of the intermediate transfer body unit 90 is accurately fitted between the intermediate transfer body positioning portions 131, and the intermediate transfer body 9 is positioned with respect to the image forming apparatus main body. Is done.

  FIG. 11 is an explanatory view showing details of the drive connecting portion of the intermediate transfer body unit 90 in a contact state. The drive coupling 124 is released from the restraining force of the connection release lever 130 shown in FIG. 9 and is thrust to the left in FIG. 11 (on the intermediate transfer body unit side) by the biasing force of the return spring 126. A shaft taper portion 152b provided on the transfer body drive shaft 125 and a coupling taper portion 152a provided on the inner diameter portion of the drive coupling 124 are engaged and positioned and fixed in the thrust direction. At this time, a gap A is provided between the driven coupling 127 and the driving coupling 124 provided on the intermediate transfer body unit 90 side, and the driving transmission position of the driving coupling 124 is only the tapered portions 152a and 152b. It is determined.

  As described above, the contact portion in the axial direction of the drive coupling 124 is an engagement portion between the shaft taper portion 152b and the coupling taper portion 152a, and the engagement portion between the driven coupling 127 and the drive coupling 124 has a shaft at the engagement portion. There is no directional contact.

  FIG. 12 is a view for explaining the configuration of the pull-in force generating means formed by the engagement between the drive coupling 124 and the driven coupling 127 provided in the intermediate transfer body unit 90. The drive ribs 151b of the drive coupling 124 have a plurality of protrusions formed on a tapered surface having an angle θ with respect to the rotation direction, and at the same time, have a plurality of recesses 151a having the same angle θ. The driving force is transmitted to the intermediate transfer body unit 90 by engaging with the driving coupling 127.

  In FIG. 12, the force F exerted by the rotation of the drive coupling 124 generates the component force of the rotational force F1 and the pull-in force F2 by the engagement of the drive rib 151b and the recessed portion 151a of the driven coupling 127, respectively. Therefore, the pulling force F2 always acts on the drive coupling 124 in the left direction (intermediate transfer member unit side) in FIG. This acts as a contact force when the shaft taper portion 152b and the coupling taper portion 152a are engaged with each other, and the drive coupling 124 is stabilized by the shaft taper portion 152b of the intermediate transfer member drive shaft 125 as described above. Is positioned.

  FIG. 13 is a detailed view for explaining the engagement state between the shaft taper portion 152b of the intermediate transfer body drive shaft 125 and the coupling taper portion 152a provided on the inner diameter portion of the drive coupling 124. The drive coupling 124 thrust moves from the separated state shown in FIG. 13 (a) by the biasing force of the return spring 126, and the tapered portions 152a and 152b are engaged in the contact state shown in FIG. 13 (b). Yes.

  The tapered portions 152a and 152b are both in the shape of a truncated cone, and when they are engaged, the drive shaft center of the intermediate transfer member drive shaft 125 and the drive center of the drive coupling 124 are automatically aligned and coincide. . As a result, the driving coupling 124 always generates a pulling force toward the intermediate transfer body unit 90 while being driven by the above-described pulling force generating means, so that the intermediate transfer body driving shaft 125 and the driving coupling 124 are always stably provided. The drive center is aligned, so that it is possible to eliminate any drive unevenness due to fitting play (gap) in the drive transmission to the intermediate transfer body unit 90.

[Other Embodiments]
In the above-described embodiment, an example in which the drive transmission device is used in an electrophotographic image forming apparatus using an intermediate transfer member has been described. However, the drive transmission device described above can also be applied to image forming apparatuses of other recording methods. Furthermore, it can be suitably used not only for the image forming apparatus but also for an apparatus that includes a unit that can be attached to and detached from the apparatus main body and that transmits drive to the unit from the apparatus main body.

1 is a longitudinal sectional view showing an overall configuration according to a first embodiment in a color laser printer to which the present invention is applied. In the color laser printer to which the present invention is applied, it is a longitudinal sectional view for explaining the configuration of the primary transfer according to the first embodiment. 1 is a perspective view illustrating a configuration according to a first embodiment in a color laser printer to which the present invention is applied. In the color laser printer to which the present invention is applied, it is a configuration diagram illustrating a contact / separation mechanism of the intermediate transfer body unit according to the first embodiment. In the color laser printer to which the present invention is applied, it is a configuration diagram illustrating a drive transmission configuration of the drive unit and the intermediate transfer body unit according to the first embodiment. 1 is a configuration diagram illustrating a configuration of a drive unit according to a first embodiment in a color laser printer to which the present invention is applied. FIG. 3 is a detailed diagram illustrating a driving and rolling configuration of a driving unit and an intermediate transfer body unit according to the first embodiment in a color laser printer to which the present invention is applied. In the color laser printer to which the present invention is applied, it is a configuration diagram illustrating a contact / separation mechanism of the intermediate transfer body unit according to the first embodiment. In the color laser printer to which the present invention is applied, it is a configuration diagram illustrating a drive transmission configuration of the drive unit and the intermediate transfer body unit according to the first embodiment. 1 is a perspective view illustrating a configuration according to a first embodiment in a color laser printer to which the present invention is applied. FIG. 3 is a detailed diagram illustrating a drive transmission configuration of a drive unit and an intermediate transfer body unit according to the first embodiment in a color laser printer to which the present invention is applied. In the color laser printer to which this invention is applied, it is detail drawing explaining the structure of the drawing-in force generation means concerning 1st Embodiment. FIG. 5 is a detailed diagram illustrating a positioning configuration related to drive transmission between the drive unit and the intermediate transfer body unit according to the first embodiment in the color laser printer to which the present invention is applied. It is a block diagram explaining the structure of the prior art example of a color laser printer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum 2 ... Transfer material 3 ... Process cartridge 3S ... Sleeve 4 ... Developing device 5 ... Charging means 6 ... Scanner part 6a ... Polygon mirror 6b ... Imaging lens 7 ... Cassette 8a ... Feed roller 8b ... Feed roller 8c ... retard roller 8d ... feeding guide 8e ... registration roller 9 ... intermediate transfer member 9a ... drive roller 9b ... secondary transfer counter roller 9c ... tension roller 9x ... center 9y ... both ends
10 ... Secondary transfer roller
12a ... Cleaning blade
12b ... Metal plate
13… Fur brush
14… Intermediate transfer member cleaning unit
14a ... cleaner container
17… Fixing part
18… Fixing roller
19… Pressure roller
20, 21, 22… discharge roller
23… discharge section
45… Drum motor
46… Pinion
47… Intermediate gear
48… Large gear
49… Drum drive shaft
51… Bearings
52… Triangular coupling
57… Positioning part
62… Return spring
71… Primary transfer roller
80Y, 80M, 80C, 80K ... Developer
90 ... Intermediate transfer unit
101… Rear side plate
103… Drive unit
103ITB ... Drive unit
104… Drive frame
105a, 105b ... Locating pin
120… Pinion
121… Intermediate gear
122… Large gear
123… Coupling holder
124… Drive coupling
125… Drive shaft
126… Return spring
127… Driven coupling
128… Drive roller shaft
129… Intermediate transfer member frame
130… Connection release lever
131 ... Intermediate transfer member positioning part
132… Positioning fitting
151a ... recess
151b ... Drive rib
152a ... Coupling taper
152b… shaft taper
200… Release spring
205a ... Eccentric cam receiver
209… Eccentric camshaft
210, 216 ... Eccentric cam
210a ... Convex part

Claims (2)

A drive coupling that is supported so as to be movable in the axial direction on the drive shaft, and the drive coupling is provided in a unit that can be attached to and detached from the apparatus main body. The drive is provided with a pull-in force generating means for generating a pull-in force at the time of driving transmission at the engaging portion between the drive coupling and the driven coupling. In the transmission device,
A shaft taper portion is provided on the drive shaft, and a coupling taper portion engageable with the shaft taper portion is provided on an inner diameter portion of the drive coupling,
At the time of driving transmission, the shaft taper portion and the coupling taper portion come into contact with each other by the pulling force of the pulling force generating means, and the drive coupling is positioned in the axial direction with respect to the drive shaft, and the drive A drive transmission device characterized in that a shaft and a drive center of the drive coupling are aligned . An image forming apparatus comprising: an image carrier; and an intermediate transfer member onto which a toner image formed on the image carrier is transferred, wherein the toner image transferred onto the intermediate transfer member is transferred to a recording medium. And
The intermediate transfer member is configured as a unit detachable from the apparatus main body,
The image forming apparatus according to claim 1, wherein the drive transmission device transmits a driving force to the unit.

Images