JP5156364B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus having an intermediate transfer unit.

  As an image forming apparatus, a color copier using an intermediate transfer belt is known. In such a color copier, first, the process of primary transfer of each color toner image developed on the surface of each of the four photosensitive drums onto the intermediate transfer belt is sequentially repeated, so that each color toner image is transferred onto the intermediate transfer belt. A superimposed full-color toner image is formed. The color copier then forms a predetermined full-color image on the surface of the paper by secondarily transferring the full-color toner image on which the respective color toner images are superimposed onto the predetermined paper.

  In this color copying machine, a secondary transfer roller disposed in an intermediate transfer unit is used for secondary transfer. The intermediate transfer unit includes, for example, a rotation drive gear disposed at a fixed position with respect to the color copying machine main body, a driven gear for rotating the secondary transfer roller connected to the secondary transfer roller, and a rotation drive gear. A transmission gear that contacts the driven gear and transmits the rotational driving force in the rotary driving gear to the driven gear is configured. The intermediate transfer unit is brought into contact with and separated from a contact position where the secondary transfer roller is brought into contact with the intermediate transfer belt and a separation position where the intermediate transfer belt is separated from the intermediate transfer belt by a predetermined contact / separation unit.

  When the intermediate transfer unit is in the contact position, the secondary transfer roller to which the secondary transfer bias is applied is disposed so as to sandwich the sheet together with the intermediate transfer unit. As a result, the sheet is pressed against the intermediate transfer belt, and the full-color toner image primarily transferred to the intermediate transfer belt is secondarily transferred to the surface of the sheet.

  Here, when the secondary transfer roller is brought into contact with the intermediate transfer belt, the secondary transfer roller needs to be disposed at an accurate position. That is, the intermediate transfer unit moved by the contact / separation means needs to be positioned at an accurate position so that the secondary transfer roller is correctly brought into contact with the intermediate transfer belt.

On the other hand, an image forming apparatus having a position regulating means for positioning the secondary transfer roller has been proposed. Specifically, the secondary transfer roller is formed by fitting pin members as positioning members formed at both ends of the secondary transfer roller into notches formed in a box-shaped guide disposed on the opposing roller side. An image forming apparatus that accurately positions the image has been proposed (see, for example, Patent Document 1).
Japanese Patent No. 3596719

  However, since the intermediate transfer unit is mounted at a fixed position with respect to the image forming apparatus main body, when the intermediate transfer unit is positioned at the contact position by the position restricting member of Patent Document 1, the intermediate transfer unit is positioned at two different fixed positions. It will be fixed. In this case, if an error occurs due to a manufacturing tolerance or manufacturing accuracy in a housing or the like constituting the intermediate transfer unit, the intermediate transfer unit and related members may be adversely affected. For this reason, the intermediate transfer unit is designed so that the distance between the rotation drive unit and the positioning member can be changed by the amount of the error so that the above-described error is not adversely affected.

  Here, when the above-mentioned distance is changed, the distance between each member arrange | positioned at an intermediate transfer unit is also changed similarly. For example, the distance between the rotation drive gear and the rotation drive gear is changed. In this case, by changing the distance between the transmission gear and the rotation drive gear or the rotation drive gear, abnormal noise due to gear tooth bottom generation, torque increase, gear tooth skipping, and gear tip cracking Etc. may occur.

  The present invention relates to a rotational drive unit, a rotational drive unit coupled to a secondary transfer roller, and a driving force transmission that contacts the rotational drive unit and the rotational drive unit with a predetermined urging force applied thereto. An image forming apparatus including an intermediate transfer unit including a means, wherein the rotational driving force in the rotational drive unit is suitably transmitted to the rotational drive unit even when an error due to tolerance or manufacturing accuracy occurs in the intermediate transfer unit. An object of the present invention is to provide an image forming apparatus.

  The present invention provides one or more image carriers having an electrostatic latent image formed on the surface, and one or more developments for developing a toner image on the electrostatic latent images formed on the one or more image carriers. A secondary transfer nip that forms a secondary transfer nip in contact with the intermediate transfer belt, an intermediate transfer belt on which the toner image formed on the one or more image carriers is primarily transferred, a rotation drive unit, and the intermediate transfer belt A roller, a rotationally driven portion connected in the rotational axis direction of the secondary transfer roller and spaced from the rotational driving portion, and a rotational driving force of the rotational driving portion transmitted to the rotationally driven portion. An intermediate transfer unit that causes the intermediate transfer unit to contact the intermediate transfer belt, and the secondary transfer roller does not contact the intermediate transfer belt. Separation position Comprising a moving means for moving, to said driving force transmitting means, an image forming apparatus is brought into contact with said driven rotatable portion and the rotary drive unit in a state in which a predetermined biasing force is applied.

  Further, the driving force transmission means presses the transmission gear portion against the rotation driving portion and the rotation driven portion, and the transmission gear portion that contacts the rotation driving portion and the rotation driven portion. It is preferable to have a first biasing member that biases the

  In addition, the transmission gear unit moves to the rotation driving unit side in the state where the transmission gear unit is in contact with the rotation driving unit and the rotation driven unit, and the rotation driven. It is preferable that a restricting portion for restricting movement toward the portion side is disposed.

  The driving force transmission means includes an endless transmission belt that is hung so as to surround the rotation driving unit and the rotation driving unit, and an abutting member that is in contact with an outer surface of the transmission belt And a second urging member that urges the abutting member so as to press against the outer surface of the transmission belt.

  In addition, it is preferable to include positioning means for positioning the intermediate transfer unit at the contact position.

  According to the present invention, the rotational drive unit, the rotational drive unit coupled to the secondary transfer roller, and the drive that contacts the rotational drive unit and the rotational drive unit with a predetermined urging force applied thereto. An image forming apparatus including an intermediate transfer unit including a force transmission unit, and the rotational drive force in the rotational drive unit is suitable for the rotational drive unit even when an error due to tolerance or manufacturing accuracy occurs in the intermediate transfer unit. It is possible to provide an image forming apparatus that is transmitted to the printer.

  With reference to FIG. 1, the overall structure of a color copier 1 as an image forming apparatus in this embodiment will be described. FIG. 1 is a diagram for explaining the arrangement of each component in the color copier 1.

  The color copying machine 1 includes a document feeding unit 70 that is arranged on the upper side of the color copying machine 1 and sends a predetermined document, an image reading unit 71 that reads an image formed on the document sent by the document feeding unit 70, and Is provided. The color copier 1 includes photosensitive drums 2a, 2b, 2c, and 2d as image carriers, charging units 10a, 10b, 10c, and 10d, laser scanner units 4a, 4b, 4c, and 4d, and a developing unit. 16a, 16b, 16c, 16d, toner cartridges 5a, 5b, 5c, 5d, toner supply devices 6a, 6b, 6c, 6d, an intermediate transfer belt 7 and an intermediate transfer unit 200 including a secondary transfer roller 8. And a fixing device 9. Further, the color copier 1 includes a paper feed cassette 52 that is disposed so as to be able to be pulled out below the copier and that stores the paper T in a stacked state. The color copying machine 1 further includes a transport path 54 through which the paper T sent from the paper feed cassette 52 is transported.

  The photosensitive drums 2a, 2b, 2c, and 2d are cylindrical members. Each of the photosensitive drums 2a, 2b, 2c, and 2d is disposed so as to be rotatable around a rotation axis perpendicular to FIG. An electrostatic latent image is formed on the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d.

  The charging units 10a, 10b, 10c, and 10d are disposed above the photosensitive drums 2a, 2b, 2c, and 2d, respectively. The charging units 10a, 10b, 10c, and 10d uniformly and positively (positively) charge the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d.

  The laser scanner units 4a, 4b, 4c, and 4d are disposed above the photosensitive drums 2a, 2b, 2c, and 2d and spaced apart from the photosensitive drums 2a, 2b, 2c, and 2d, respectively. Each of the laser scanner units 4a, 4b, 4c, and 4d includes a laser light source (not shown), a polygon mirror, a polygon mirror driving motor, and the like.

  Each of the laser scanner units 4a, 4b, 4c, and 4d scans and exposes the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d based on the image information related to the image read by the image reading unit 71. Scanning exposure is performed by each of the laser scanner units 4a, 4b, 4c, and 4d, so that charges charged on the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d are removed. Thereby, electrostatic latent images are formed on the respective surfaces of the photosensitive drums 2a, 2b, 2c, and 2d.

  Each of the developing devices 16a, 16b, 16c, and 16d is disposed on the side (left side in FIG. 1) of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the developing devices 16a, 16b, 16c, and 16d develops toner images of the respective colors on the electrostatic latent images formed on the photosensitive drums 2a, 2b, 2c, and 2d. Each of the developing devices 16a, 16b, 16c, and 16d corresponds to four toner colors of yellow, cyan, magenta, and black. Each of the developing devices 16a, 16b, 16c, and 16d includes developing rollers 116a, 116b, 116c, and 116d that can be disposed to face the photosensitive drums 2a, 2b, 2c, and 2d, and a stirring roller for stirring the toner. The

Each of the toner cartridges 5a, 5b, 5c, and 5d stores toner of each color supplied to each of the developing devices 16a, 16b, 16c, and 16d. Each of the toner cartridges 5a, 5b, 5c, and 5d accommodates yellow toner, cyan toner, magenta toner, and black toner.
Each of the toner supply devices 6a, 6b, 6c, and 6d supplies the toners of the respective colors stored in the toner cartridges 5a, 5b, 5c, and 5d to the developing devices 16a, 16b, 16c, and 16d, respectively.

  Each of the drum cleaning devices 11a, 11b, 11c, and 11d is disposed on the side (right side in FIG. 1) of each of the photosensitive drums 2a, 2b, 2c, and 2d. Each of the drum cleaning devices 11a, 11b, 11c, and 11d removes toner and deposits remaining on the surfaces of the photosensitive drums 2a, 2b, 2c, and 2d.

  The toner images of the respective colors developed on the photosensitive drums 2a, 2b, 2c, and 2d are sequentially transferred to the intermediate transfer belt 7. The intermediate transfer belt 7 is arranged so as to be stretched between the driving roller 35 and the tension roller 36. Since the tension roller 36 is biased to the side away from the drive roller 35 by the spring 38, a predetermined tension is applied to the intermediate transfer belt 7.

  Primary transfer rollers 37a, 37b, 37c, and 37d are arranged to face each other on the opposite side of the intermediate transfer belt 7 from the photosensitive drums 2a, 2b, 2c, and 2d. The primary transfer rollers 37a, 37b, 37c, and 37d are respectively transferred to the intermediate transfer belt 7 with the respective color toner images developed on the photosensitive drums 2a, 2b, 2c, and 2d by a voltage application unit (not shown). The primary transfer bias is applied.

  Predetermined portions of the intermediate transfer belt 7 are sandwiched between the primary transfer rollers 37a, 37b, 37c, and 37d and the photosensitive drums 2a, 2b, 2c, and 2d, respectively. The predetermined portion thus sandwiched is pressed against the surface of each of the photosensitive drums 2a, 2b, 2c, and 2d. In this way, primary transfer nips N1a, N1b, N1c, and N1d are formed, and the color toner images developed on the photosensitive drums 2a, 2b, 2c, and 2d are sequentially transferred to the intermediate transfer belt 7. As a result, a full-color toner image is formed on the intermediate transfer belt 7.

  The secondary transfer roller 8 secondarily transfers the toner image primarily transferred to the intermediate transfer belt 7 onto the paper T. A secondary transfer bias for transferring the toner image on the intermediate transfer belt 7 to the paper T is applied to the secondary transfer roller 8 by a voltage application unit (not shown).

  The secondary transfer roller 8 is brought into contact with and separated from the intermediate transfer belt 7. Specifically, the secondary transfer roller 8 is configured to be movable between a contact position where the secondary transfer roller 8 is in contact with the intermediate transfer belt 7 and a spaced position where the secondary transfer roller 8 is separated from the intermediate transfer belt 7. Specifically, the secondary transfer roller 8 is moved to the contact position when the toner image primarily transferred onto the surface of the intermediate transfer belt 7 is secondarily transferred to the paper T, and is separated from the other position. Moved to. Here, the contact / separation operation of the secondary transfer roller 8 is performed by rotating the entire intermediate transfer unit 200 as described later.

  A counter roller 108 is disposed on the side of the intermediate transfer belt 7 that faces the secondary transfer roller 8. A predetermined portion of the intermediate transfer belt 7 is sandwiched between the secondary transfer roller 8 and the opposing roller 108. Then, the paper T is pressed against the surface of the intermediate transfer belt 7 (the side on which the image is primarily transferred). In this way, the secondary transfer nip N2 is formed, and the toner image primarily transferred to the intermediate transfer belt 7 is secondarily transferred to the paper T.

  Here, the secondary transfer roller 8 is included in the intermediate transfer unit 200. The intermediate transfer unit 200 accommodates the secondary transfer roller 8 and rotatably supports the secondary transfer roller 8, and a rotation drive gear 210 as a rotation drive unit disposed on a side surface of the housing 201. A roller-side gear 220 as a rotationally driven portion disposed on the side surface of the housing 201 in the rotational axis direction of the secondary transfer roller 8, and a transmission disposed in contact with the rotational drive gear 210 and the roller-side gear 220. And an idle gear 230 as a gear unit. The intermediate transfer unit 200 is configured such that the secondary transfer roller 8 has an intermediate transfer belt 7 centered on a rotation axis I (see FIGS. 2 and 3) of a shaft 310 (see FIGS. 2 and 3) to be described later by contact and separation means described later. Is moved to a contact position that can contact the intermediate transfer belt 7 and a separation position that does not contact the intermediate transfer belt 7. The intermediate transfer unit 200 will be described in detail later.

  The fixing device 9 melts and fixes each color toner constituting the toner image secondarily transferred onto the paper T. The fixing device 9 includes a heating roller 9a heated by a heater, and a pressure roller 9b pressed against the heating roller 9a. The heating roller 9a and the pressure roller 9b convey the paper T onto which the toner image is secondarily transferred so as to sandwich the paper T. By being conveyed so as to be sandwiched between the heating roller 9a and the pressure roller 9b, the toner transferred onto the paper T is melted and fixed.

  A belt cleaning device 40 for cleaning the intermediate transfer belt 7 is disposed between the secondary transfer roller 8 and the tension roller 36. The belt cleaning device 40 includes a cleaning brush 41 that is in sliding contact with the surface of the intermediate transfer belt 7, a cleaning roller 42 that is disposed so as to be in contact with the cleaning brush 41, and a tip that is in contact with the surface of the cleaning roller 42. The blade 43 is disposed, and the recovery spiral 44 is disposed below the blade 43.

  On the lower side of the color copying machine 1, a paper feed cassette 52 that accommodates the paper T is disposed so as to be pulled out in the horizontal direction. In the paper feed cassette 52, paper T is stored in a stacked state. In the paper feed cassette 52, a placement plate 60 on which the paper T is placed is disposed. The paper T placed on the placement plate is sent out to the transport path 54 by the cassette paper feed unit 51 disposed at the paper feed side end of the paper feed cassette 52 (right end in FIG. 1). The cassette paper feeding unit 51 includes a double feed prevention mechanism including a forward feed roller 61 for taking out the paper T on the placement plate 60 and a roller pair 63 for feeding the paper T one by one to the transport path 54.

  A conveyance path 54 for conveying the paper T is formed between the cassette paper feeding unit 51 and the discharge unit 50. The conveyance path 54 includes a first conveyance path 55 from the cassette paper feeding unit 51 to the secondary transfer roller 8, a second conveyance path 56 from the secondary transfer roller 8 to the fixing device 9, and a discharge unit 50 from the fixing device 9. And the third conveyance path 57. Further, a branching claw 58 is provided at the outlet of the fixing device 9, and the paper T is placed in the first conveyance path 55 between the branching claw 58 and a curved path 55 a described later in the first conveyance path 55. A return conveyance path 59 for returning is formed.

  The first conveyance path 55 conveys the paper T fed from the paper feed cassette 52 upward, while turning the conveyance direction to the left in FIG. 1 and the curved path 55a to the secondary transfer roller 8. Straight path 55b. In the first conveyance path 55, a guide plate and a roller pair that convey the paper T while guiding it are arranged. Further, a sensor for detecting the paper T and a registration roller pair 80 for adjusting the skew (oblique paper feeding) of the paper T and the timing of the toner image are arranged in the first transport path 55. The sensor is disposed immediately before (on the upstream side) the registration roller pair 80 in the transport direction of the paper T. The registration roller pair 80 conveys the paper T by performing the above-described correction and timing adjustment based on the detection signal information from the sensor.

  The second transport path 56 is a linear transport path that is inclined downward toward the fixing device 9 side. A transport belt 156 that transports the paper T in a state where the paper T is placed is disposed in the second transport path 56. A sensor for detecting the paper T is disposed at a predetermined position in the second transport path 56.

  The third transport path 57 is formed so as to extend obliquely upward to the left in FIG. 1 from the exit of the fixing device 9. The third conveyance path 57 is configured to have a vertical conveyance path 57 a that is located on the downstream side of the branch claw 58 in the conveyance direction and formed upward. The paper T transported by the third transport path 57 passes through the upper surface side of the branching claw 58, is transported substantially vertically upward, and is ejected from the discharge unit 50 to the outside of the color copying machine main body M. The third transport path 57 includes a guide plate and a roller pair that transport the paper T while guiding the paper T, like the other transport paths.

  The return conveyance path 59 branches from the branch claw 58 to the lower side opposite to the third conveyance path 57 and passes below the fixing device 9, the second conveyance path 56, the secondary transfer roller 8, and the registration roller pair 80. Furthermore, it forms so that it may go upwards. The return conveyance path 59 is formed so as to merge with the curved path 55 a in the first conveyance path 55. The return conveyance path 59 is a conveyance path for returning the paper T that has passed through the fixing device 9 to the upstream side of the registration roller pair 80 disposed on the upstream side of the secondary transfer roller 8. The return conveyance path 59 is a conveyance path that is used when performing so-called double-sided printing (printing) in which toner images (including characters and the like) are printed (printed) on both sides of the paper T. For example, the paper T is returned to the first transport path 55 via the return transport path 59 in a state where the front and back surfaces are reversed by the reverse roller 600. Like the other transport paths, the return transport path 59 has a guide plate and a pair of rollers that transport the paper T while guiding it, and a sheet detection sensor is disposed at a predetermined position.

  A manual paper feed unit 64 is provided on the right side surface of the color copier 1 in FIG. The manual paper feed unit 64 includes a manual feed tray 65 that forms a side wall in the closed state, and a paper feed roller 66. The manual feed tray 65 is attached to the vicinity of the curved path 55a of the first transport path 55 so that the lower end of the manual feed tray 65 can rotate (open and close). The manual paper feed unit 64 feeds the paper T placed on the open manual feed tray 65 to the curved path 55 a of the first transport path 55.

  Next, the structure and operation of the intermediate transfer unit 200 in the first embodiment will be described with reference to FIGS. FIG. 2 is a perspective view illustrating a state in which the intermediate transfer unit 200 according to the first embodiment is disposed at the contact position. FIG. 3 is a perspective view illustrating a state in which the intermediate transfer unit 200 according to the first embodiment is disposed at the separation position. FIG. 4 is a front view illustrating a state in which the intermediate transfer unit 200 according to the first embodiment is disposed at the contact position. FIG. 5 is a front view of the housing 201 constituting the intermediate transfer unit 200 in the first embodiment. FIG. 6 is a diagram illustrating a state in which the intermediate transfer unit 200 according to the first embodiment is disposed at the contact position by the contact / separation unit. FIG. 7 is a diagram illustrating a state in which the intermediate transfer unit 200 according to the first embodiment is disposed at the separation position by the contact / separation unit.

  As shown in FIGS. 2 to 4, the intermediate transfer unit 200 accommodates the secondary transfer roller 8 and is disposed on a side surface of the housing 201, and a housing 201 that rotatably supports the secondary transfer roller 8. A rotation drive gear 210 as a rotation drive unit, a roller side gear 220 as a rotation drive unit disposed on the side surface of the housing 201 in the rotation axis J direction of the secondary transfer roller 8, and the rotation drive gear 210 and the roller side And an idle gear 230 that constitutes a driving force transmission means disposed in contact with the gear 220.

  The housing 201 has a bottom surface 202 formed below in FIG. 2, a first wall portion 203 formed on the near side in FIG. 2 and perpendicular to the bottom surface 202, and a first wall portion positioned on the left side in FIG. 2. A second wall portion 204 formed perpendicular to the wall portion 203, a protruding plate portion 205 formed on the bottom surface side of the first wall portion 203 so as to extend toward the front side in FIG. 2, and a first wall portion 203 2, and is formed so as to extend upward in FIG. 2, and is perpendicular to the thin wall portion 206 from the thin wall portion 206 and on the back side in FIG. 2. And a pin member 207 formed so as to extend.

  As shown in FIG. 5, the first wall 203 of the housing 201 has a horizontally elongated first hole 271 through which the shaft 310 (see FIGS. 2 and 3) is inserted, and an idle gear 230 (FIG. 2 and FIG. 2). The shaft portion 8a (see FIGS. 1 to 3) and the shaft portion 8a (see FIG. 1 to FIG. 3) formed at both ends of the vertically long second hole 272 through which the rotation shaft portion of the rotation shaft portion of FIG. A circular third hole 273 is formed through which (see FIGS. 2 and 3) is inserted.

  The housing 201 is attached to the color copying machine main body M so as to be rotatable about a rotation axis I (see FIGS. 2 and 3) of a shaft 310 inserted through a first hole 271 described later.

  A secondary transfer roller 8 is accommodated in the housing 201. In the housing 201, the secondary transfer roller 8 is accommodated while being rotatably supported by the housing 201. The secondary transfer roller 8 has a shaft portion 8a formed on the side of the rotation shaft J (see FIGS. 2 and 3). The shaft portion 8 a is inserted into the third hole 273 formed in the first wall portion 203 of the housing 201, so that the secondary transfer roller 8 is accommodated while being rotatably supported by the housing 201.

  A roller side gear 220 (see FIGS. 2 and 3) is coupled to the shaft portion 8a. The roller side gear 220 is disposed on the outer side opposite to the secondary transfer roller 8 with the first wall 203 interposed therebetween. By rotating the roller side gear 220, the secondary transfer roller 8 is rotated.

  As shown in FIG. 2 or 3, the roller side gear 220 is a cylindrical member and has a gear tooth portion 221 having a plurality of gear teeth 221a formed on the side surface. Further, the roller side gear 220 has a disk-like roller side flange 223 which is a surface perpendicular to the rotation axis J and is disposed on the front side surface in FIG. The roller side flange 223 is a disk-like member having a radius smaller than the tooth tip circle radius of the roller side gear 220 disposed on the outer surface of the roller side gear 220. Specifically, the roller-side flange 223 is a disk-like member having a radius substantially the same as the pitch circle radius of the roller-side gear 220.

  A gear tooth portion 221 of an idle gear 230 described later is brought into contact with the gear tooth portion 221 so as to mesh with each other. Further, an idle gear side flange 233 that constitutes a restricting portion described later is brought into contact with the roller side flange 223.

  In the housing 201, a rotation drive gear 210 connected to the shaft 310 inserted through the first hole 271 (see FIG. 5) is disposed. The rotation drive gear 210 is disposed outside the first wall 203 of the housing 201. The rotation drive gear 210 is disposed on the same side as the roller side gear 220 in the first wall 203 of the housing 201.

  The rotational drive gear 210 is a cylindrical member and has a gear tooth portion 211 having a plurality of gear teeth 211a formed on a side surface. The rotation drive gear 210 has a disk-like rotation drive side flange 213 which is a surface perpendicular to the rotation axis I and is disposed on the front surface in FIG. The rotation drive side flange 213 is a disk-shaped member having a radius smaller than the tooth tip circle radius of the rotation drive gear 210 disposed on the outer surface of the rotation drive gear 210. Specifically, the rotation drive side flange 213 is a disk-like member having a radius substantially the same as the pitch circle radius of the rotation drive gear 210.

  A gear tooth portion 231 of an idle gear 230 described later is brought into contact with the gear tooth portion 211 so as to mesh with each other. Further, an idle gear side flange 233 to be described later is brought into contact with the rotation drive side flange 213.

  As shown in FIGS. 2 to 4, the rotary drive gear 210 is movable in the horizontal direction because the shaft 310 to be connected is inserted into the first hole 271 formed in a horizontally long shape (long shape in the horizontal direction). Configured. In other words, the horizontal distance B between the rotation axis I of the rotation drive gear 210 and the rotation axis J of the roller side gear 220 in FIG.

  The housing 201 is provided with an idle gear 230 that is coupled to a first shaft portion (not shown) that is inserted into the vertically long second hole 272 (see FIG. 5). The idle gear 230 is disposed outside the first wall 203 of the housing 201. The idle gear 230 is disposed on the same side of the first wall 203 of the housing 201 as the rotational drive gear 210 and the roller side gear 220.

  The idle gear 230 is a cylindrical member and has a gear tooth portion 231 having a plurality of gear teeth 231a formed on a side surface. Further, the idle gear 230 has a disk-shaped idle gear side flange 233 that is disposed on a front surface in FIG. As described above, the idle gear side flange 233 is a member that constitutes a restricting portion, and is a disk-shaped member having a radius smaller than the tooth tip circle radius of the idle gear 230 disposed on the outer surface of the idle gear 230. . Specifically, the idle gear side flange 233 is a disk-shaped member having a radius substantially the same as the pitch circle radius of the idle gear 230. Here, as described above, since the radius of each flange is set to be substantially the same as the pitch circle radius in each gear, the peripheral speed difference between the flanges can be eliminated. Thereby, it can suppress that the outer periphery of each flange is shaved by the circumferential speed difference.

  The idle gear 230 is configured to be movable in the vertical direction because the first shaft portion (not shown) is inserted into the vertically long second hole 272 (see FIG. 5). Furthermore, the idle gear 230 is configured to be movable in the vertical direction by a force applied by a spring member 240 as a first urging member described later.

  The idle gear 230 is formed with a second shaft portion 235 that extends to the opposite side of the first shaft portion (not shown). The second shaft portion 235 includes a bearing portion 237 that rotatably receives the second shaft portion 235, a holding member 245 that is disposed below the bearing portion 237 and holds the bearing portion 237, a holding member 245, and a protruding plate portion 205 is supported by a spring member 240 that is arranged in a state having elasticity F with 205.

A cylindrical support part 250 is formed on the protruding plate part 205. The support member 250 is fitted with a spring member 240 formed so as to be spirally wound.
One end side (downward) of the spring member 240 is attached to the protruding plate portion 205 via the support portion 250. A holding member 245 is attached to the other end side (upper side) of the spring member 240.

  The holding member 245 includes a U-shaped holding portion 246 that holds the bearing portion 237 and an attachment portion 247 that is connected to the holding portion 246. The holding member 245 is attached to the spring member 240 with the attachment portion 247 fitted to the other end side (upward) of the spring member 240.

  The spring member 240 is arranged in a state shorter than the natural length. The spring member 240 is arranged in a state of having an elastic force F directed upward. That is, the holding member 245 that holds the second shaft portion 235 via the bearing portion 237 is biased upward by the spring member 240.

  As described above, the idle gear 230 is urged upward by the spring member 240 via the holding member 245 in FIG. As a result, the idle gear 230 is biased so as to be pressed against both the rotation drive gear 210 and the roller side gear 220 by the spring member 240 via the holding member 245.

  Here, in the present embodiment, the second shaft portion 235 is held by the holding member 245 via the bearing portion 237, but the second shaft portion 235 is configured to be directly held by the holding member 245. Also good.

  The idle gear 230 is disposed in contact with both the rotation drive gear 210 and the roller side gear 220. Specifically, the idle gear 230 is arranged such that the gear tooth portion 231 of the idle gear 230 is in contact with both the gear tooth portion 211 of the rotational drive gear 210 and the gear tooth portion 221 of the roller side gear 220. That is, the idle gear 230 is disposed such that the gear tooth portion 231 of the idle gear 230 meshes with the gear tooth portion 211 of the rotational drive gear 210 and the gear tooth portion 221 of the roller side gear 220. The idle gear 230 as the transmission gear unit transmits the rotational driving force in the rotational driving gear 210 to the roller side gear 220. The rotational driving force transmitted to the roller side gear 220 via the idle gear 230 rotates the roller side gear 220 and the secondary transfer roller 8 to which the roller side gear 220 is connected.

  The idle gear 230 is disposed in contact with both the rotation drive gear 210 and the roller side gear 220 in a state where the idle gear side flange 233 is in contact with the rotation drive side flange 213 and the roller side flange 223. Specifically, in the idle gear 230, the gear tooth portion 231 in the idle gear 230 is the gear tooth in the rotational drive gear 210 in a state where the idle gear side flange 233 is in contact with the rotational drive side flange 213 and the roller side flange 223. The portion 211 and the roller side gear 220 are arranged so as to mesh with both the gear teeth 221.

  Since the idle gear 230 is urged by the spring member 240 so as to be pressed against the rotation drive gear 210 and the roller side gear 220, each gear is changed even when the distance between the rotation drive gear 210 and the roller side gear 220 is changed. The meshing state between the parts is maintained. Further, excessive movement of the idle gear 230 to the rotational drive gear 210 side and the roller side gear 220 side is restricted by the idle gear side flange 233. That is, the idle gear 230 is disposed in contact with the rotation drive gear 210 and the roller side gear 220 in a state where the meshing between the gear tooth portions is suitably maintained.

  The intermediate transfer unit 200 is configured to be rotatable about a rotation axis I of the shaft 310 to a contact position shown in FIG. 2 and a separation position shown in FIG. Specifically, the intermediate transfer unit 200 rotates to a contact position where the secondary transfer roller 8 can contact the intermediate transfer belt 7 and a separation position where the secondary transfer roller 8 does not contact the intermediate transfer belt 7. Configured to be possible. The intermediate transfer unit 200 is rotationally moved around the rotation axis I by a cam mechanism 390 (see FIGS. 6 and 7), which will be described later as contact / separation means. The intermediate transfer unit 200 is moved to the contact position when the toner image primarily transferred to the intermediate transfer belt 7 is secondarily transferred to the paper T to form the secondary transfer nip N2, and in other cases. It is moved to the separation position.

  As shown in FIGS. 6 and 7, the cam mechanism 390 as the contact / separation means is disposed so as to mesh with the drive motor 400, the motor side gear 405 that transmits the rotational driving force of the drive motor 400, and the motor side gear 405. Intermediate gear 410, cam-side gear 420 arranged to mesh with intermediate gear 410, and eccentric cam 430 connected to cam-side gear 420.

  The intermediate transfer unit 200 is moved to the contact position and the separation position in response to the rotation of the eccentric cam 430. Specifically, the rotational driving force from the drive motor 400 is transmitted to the intermediate gear 410 via the motor side gear 405 connected to the drive motor 400. The rotational driving force transmitted to the intermediate gear 410 is transmitted to the cam-side gear 420 attached to the end of the eccentric cam 430 in the rotational axis direction. Thereby, the eccentric cam 430 is rotated. Then, the intermediate transfer unit 200 (housing 201) that is abutted and supported by the eccentric cam 430 from below is rotated and moved between the abutting position and the separated position around the rotation axis I according to the rotation of the eccentric cam 430. The For example, the intermediate transfer unit 200 (housing 201) rotates from the contact position shown in FIG. 6 to the separated position shown in FIG. 7 in response to the rotation of the eccentric cam 430 by the rotational driving force transmitted from the drive motor 400. It is rotated around the axis I. As shown in FIG. 7, when the eccentric cam 430 rotates in the direction of arrow r, the intermediate transfer unit 200 (housing 201) rotates in the direction of arrow R from the contact position and moves to the separation position.

  As shown in FIG. 2, the intermediate transfer unit 200 includes a pin member 207 constituting positioning means, and a notch 301 formed at the outer edge of the U-shaped wall 300 fixed to the color copying machine main body M. It is positioned at the contact position. Specifically, the intermediate transfer unit 200 is positioned at the contact position when the pin member 207 is fitted into the notch 301 formed in the U-shaped wall 300.

  As shown in FIGS. 3 and 4, the notch 301 is formed in a U shape. A curved locking portion 301 a in the notch 301 is formed corresponding to the outer peripheral shape of the pin member 207. Between the opening 301b and the locking portion 301a in the notch 301, an introduction portion 301c is formed that is movable with the pin member 207 inserted. The introduction part 301c guides the movement of the pin member 207.

  The notch 301 is formed such that the opening 301b is wider than the width of the introduction portion 301c (the vertical direction in FIGS. 3 and 4). Moreover, the introduction part 301c is formed so that the width becomes wider toward the opening part 301b. Thereby, when the intermediate transfer unit 200 is pivotally moved from the separated position to the contact position, the pin member 207 is easily inserted into the notch 301.

Subsequently, the operation of the present embodiment will be described with reference to FIGS. 4 and 5.
As shown in FIG. 4, the intermediate transfer unit 200 is positioned and fixed at a contact position by a shaft 310 (see FIGS. 2 and 3) and a pin member 207 fitted in the notch 301. The shaft 310 is disposed at a fixed position with respect to the color copying machine main body M. Further, since the notch 301 is formed at a position fixed to the color copier body M, the pin member 207 fitted to the notch 301 is similarly fixed to the color copier body M. Placed in position. That is, the intermediate transfer unit 200 is positioned and fixed at the contact position by the shaft 310 disposed at the fixed position with respect to the color copying machine main body M and the pin member 207 disposed at the fixed position with respect to the color copying machine main body M. . In other words, the distance A in the horizontal direction between the shaft 310 and the pin member 207 fitted in the notch 301 is set to a predetermined fixed value (fixed distance).

  Here, an error may occur with respect to a predetermined fixed value at the distance A in the horizontal direction between the shaft 310 and the pin member 207 due to a manufacturing tolerance and manufacturing accuracy. In order to compensate for this error, the first hole 271 is formed in a horizontally long shape as shown in FIG. In other words, when the first hole 271 through which the shaft 310 (see FIGS. 2 and 3) is inserted is circular, the position of the first hole 271 is formed to be shifted from a predetermined position due to tolerance or the like. The horizontal distance A described above is different from a predetermined fixed distance. In this case, there is a problem that the pin member 207 is difficult to be inserted into the notch 301 (see FIG. 4) when the intermediate transfer unit 200 (see FIGS. 2 and 3) is rotated, and the pin member 207 is notch 301. There may be a problem that a load is applied to the shaft 310 in a contact state fitted to the shaft 310. In order to suppress the occurrence of such a problem, the first hole 271 is formed in a horizontally long shape so that the above-described horizontal distance A is adjusted to a predetermined fixed distance.

  When the horizontal distance A between the shaft 310 and the pin member 207 is adjusted to be a predetermined fixed distance, the distance B between the rotation drive gear 210 and the roller side gear 220 connected to the shaft 310 is adjusted. The distance is changed by the distance corresponding to the error. When the position of the idle gear 230 is fixed, the distance B between the rotational drive gear 210 and the roller side gear 220 is changed, thereby generating abnormal noise due to contact with the gear tooth bottom, increasing torque, gear tooth skipping, A problem that the tip of the gear tooth breaks may occur.

  On the other hand, in the present embodiment, in order to cope with the change of the distance B, the idle gear 230 is configured to be movable in the vertical direction, and the idle gear 230 is moved by the spring member 240 to the rotational drive gear 210 and the roller side gear. It is urged to press against 220. Specifically, a second hole 272 into which a first shaft portion (not shown) in the idle gear 230 is inserted is formed in a vertically long shape and idled via a bearing portion 237 that receives the second shaft portion 235 by the spring member 240. The gear 230 is urged so as to press against the rotation drive gear 210 and the roller side gear 220.

  With this configuration, when the horizontal distance B between the rotation drive gear 210 and the roller side gear 220 is changed, the idle gear 230 moves in the vertical direction, and the rotation drive gear 210, the roller side gear 220, It is possible to maintain a state in contact with. In particular, when the distance B is increased, the state where the idle gear 230 is in contact with the rotation drive gear 210 and the roller side gear 220 is preferably maintained, and the rotation drive force in the rotation drive gear 210 is increased. To communicate.

  Further, since the idle gear side flange 233 is brought into contact with the rotational drive side flange 213 and the roller side flange 223 in the meshed state, the idle gear 230 is restricted from excessively moving toward the rotational drive gear 210 and the roller side gear 220. The With this configuration, when the distance B is changed, the idle gear 230 is maintained in contact with the rotation drive gear 210 and the roller side gear 220 and is suppressed from being excessively close. That is, even when the distance B is changed, the idle gear 230 is in contact with the rotation drive gear 210 and the roller side gear 220 in a suitable meshing state.

  According to the present embodiment, when the distance B between the rotation drive gear 210 and the roller side gear 220 is changed to be long, the idle gear 230 biased by the spring member 240 is moved, so that the rotation drive is performed. The rotational driving force in the gear 210 is suitably transmitted to the roller side gear 220. In this case, it is possible to prevent the gear teeth from jumping and the gear teeth from cracking.

  Further, according to the present embodiment, when the distance B between the rotational drive gear 210 and the roller side gear 220 is changed so as to be shortened, the rotational drive force in the rotational drive gear 210 is moved by moving the idle gear 230. Is suitably transmitted to the roller side gear 220. Further, since the idle gear 230 is prevented from excessively approaching the rotational drive gear 210 and the roller side gear 220 by the idle gear side flange 233, the idle gear 230 maintains the optimal meshing state while the rotational drive gear 210 is maintained. Can be transmitted to the roller side gear 220. In this case, the generation of abnormal noise and the increase in torque due to the gear bottom contact are suppressed.

  That is, according to the present embodiment, the rotational driving force in the rotational driving gear 210 is suitably transmitted to the roller side gear 220 even when an error due to tolerance or manufacturing accuracy occurs in the intermediate transfer unit 200.

  Next, the intermediate transfer unit 200A in the second embodiment will be described with reference to FIG. FIG. 8 is a perspective view illustrating a state in which the intermediate transfer unit 200A according to the second embodiment is disposed at the contact position. Hereinafter, the intermediate transfer unit 200 </ b> A according to the second embodiment will be described mainly focusing on the configuration and the like different from the intermediate transfer unit 200 according to the first embodiment. The description of the same configuration as the intermediate transfer unit 200 in the first embodiment is omitted.

  As shown in FIG. 8, the intermediate transfer unit 200 </ b> A in the second embodiment is a rotation drive pulley 210 </ b> A as a rotation drive unit connected to the shaft 310 and a rotation drive unit connected to the secondary transfer roller 8. The roller-side pulley 220A, the endless transmission belt 230A that is hung so as to surround the rotation drive pulley 210A and the roller-side pulley, and the lower side of the transmission belt 230A are disposed in contact with the outer surface of the transmission belt 230A. A contact pulley 500 as a contact member, and a spring member 240A as a second urging member that urges the contact pulley 500 toward the transmission belt 230A. In the second embodiment, the driving force transmission means includes a transmission belt 230A, a contact pulley 500, and a spring member 240A.

The contact pulley 500 is attached in a rotatable state to a plate member 502 attached to the first wall 203 of the housing 201 so as to be movable in the vertical direction.
One end of the spring member 240 </ b> A is fixed to the protruding plate portion 205, and the other end is attached to a protruding portion 504 formed on the plate member 502. The spring member 240A is attached in a state having an elastic force F1. The plate member 502 is urged upward by the spring member 240A attached to the protruding portion 504. That is, the contact pulley 500 is biased upward by the spring member 240A. Specifically, the contact pulley 500 is biased by the spring member 240A so as to be pressed against the outer surface of the portion located on the lower side of the transmission belt 230A. In other words, the contact pulley 500 is urged so as to push up a portion located on the lower side of the transmission belt 230A. As a result, a predetermined tension FA is generated in the transmission belt 230A.

  Further, as in the case of the first embodiment, the rotational drive pulley 210 </ b> A and the distance A (see FIG. 4) in the horizontal direction between the pin member 207 fitted to the notch 301 are changed, thereby rotating the drive pulley. When the horizontal distance B (see FIG. 4) between 210A and the roller-side pulley 220A is changed, the contact pulley 500 biased by the spring member 240A moves in the vertical direction, and the tension FA in the transmission belt 230A is increased. Maintain above a predetermined level.

  Thereby, even when the horizontal distance B between the rotation driving pulley 210A and the roller side pulley 220A is changed, the transmission belt 230A transmits the rotation driving force in the rotation driving pulley 210A to the roller side pulley 220A.

  According to the present embodiment, it is possible to obtain the effects obtained in the intermediate transfer unit 200 in the first embodiment.

  As mentioned above, although preferred embodiment was described, this invention can be implemented with a various form, without being limited to embodiment mentioned above. For example, in the present embodiment, the color copying machine 1 is described as the image forming apparatus, but the present invention is not limited to this, and may be a monochrome copying machine, a printer, a facsimile machine, or a multifunction machine of these.

  Moreover, in this embodiment, although the helical spring member was demonstrated as a 1st urging member and a 2nd urging member, it is not limited to this, It is not limited to this, It is by the material which has elasticity, such as a leaf | plate spring and a rubber member. It may be a configured member.

  In this embodiment, as positioning means, a pin member 207 disposed in the intermediate transfer unit 200, and a notch 301 formed on the outer edge of the U-shaped wall 300 fixed to the color copying machine main body M However, the present invention is not limited to this. For example, as a positioning unit, a pin-like member may be formed on the color copying machine main body M side, and a notch may be formed on the intermediate transfer unit 200 side.

2 is a diagram for explaining the arrangement of each component in the color copier 1. FIG. FIG. 6 is a perspective view illustrating a state where the intermediate transfer unit 200 according to the first embodiment is disposed at a contact position. FIG. 6 is a perspective view illustrating a state where the intermediate transfer unit 200 according to the first embodiment is disposed at a separation position. 6 is a front view illustrating a state in which the intermediate transfer unit 200 according to the first embodiment is disposed at a contact position. FIG. FIG. 3 is a front view of a housing 201 constituting the intermediate transfer unit 200 in the first embodiment. FIG. 6 is a diagram illustrating a state in which the intermediate transfer unit 200 according to the first embodiment is disposed at a contact position by a contact / separation unit. FIG. 6 is a diagram illustrating a state in which the intermediate transfer unit 200 according to the first embodiment is disposed at a separation position by a contact / separation unit. FIG. 10 is a perspective view illustrating a state where an intermediate transfer unit 200A according to a second embodiment is disposed at a contact position.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Color copier (image forming apparatus), 2a, 2b, 2c, 2d ... Photosensitive drum (image carrier), 16a, 16b, 16c, 16d ... Developing device, 7 ... Intermediate transfer belt, 8 ...... Secondary transfer roller, 200 ... Intermediate transfer unit, 201 ... Housing, 207 ... Pin member (positioning means), 210 ... Rotation drive gear (rotation drive part), 213 ... Rotation drive side flange (regulation) Part), 220 ... roller side gear (rotation driven part), 223 ... roller side flange (regulation part), 230 ... idle gear (driving force transmission means, transmission gear part), 230A ... transmission belt (drive) Force transmission means), 233... Idle gear side flange (regulating portion), 240... Spring member (first urging member), 240 A... Spring member (second urging member), 301. Positioning means , 390 ...... cam mechanism (moving means) 500 ...... contact pulley (abutting member), I ...... rotating shaft, J ...... rotation axis, K ...... rotating shaft, N2 ...... 2 transfer nip

Claims (4)

One or more image carriers having electrostatic latent images formed on the surface;
One or more developing devices for developing a toner image on the electrostatic latent image formed on the one or more image carriers;
An intermediate transfer belt on which a toner image formed on the one or more image carriers is primarily transferred;
A rotation drive unit, a secondary transfer roller that abuts on the intermediate transfer belt to form a secondary transfer nip, and a rotation shaft of the secondary transfer roller are connected in the direction of the rotation axis and spaced apart from the rotation drive unit. An intermediate transfer unit, and a rotation driving unit that transmits a rotation driving force in the rotation driving unit to the rotation driving unit.
Contact / separation means for moving the intermediate transfer unit between a contact position where the secondary transfer roller contacts the intermediate transfer belt and a separation position where the secondary transfer roller does not contact the intermediate transfer belt;
The rotation drive unit is supported so that a distance between the rotation drive unit and the rotation drive unit can be changed,
The driving force transmission means is
A transmission gear portion that is in contact with the rotation drive portion and the rotation drive portion;
A first urging member that urges the transmission gear portion to press against the rotation drive portion and the rotation drive portion, and the drive force transmission means is applied with a predetermined urging force . An image forming apparatus in contact with the rotation drive unit and the rotation drive unit in a state. The transmission gear portion includes the movement of the transmission gear portion toward the rotation driving portion and the rotation driving portion side in a state where the transmission gear portion is in contact with the rotation driving portion and the rotation driving portion. The image forming apparatus according to claim 1 , wherein a restricting portion that restricts movement to is disposed. The driving force transmission means is
An endless transmission belt hung so as to surround the rotation drive unit and the rotation drive unit;
A contact member that is in contact with an outer surface of the transmission belt;
The image forming apparatus according to claim 1, further comprising: a second urging member that urges the abutting member to press against the outer surface of the transmission belt. The image forming apparatus according to any one of claims 1-3; and a positioning means for positioning the intermediate transfer unit to the contact position.

Images