JPH0581859U - Oil transfer prevention mechanism for recording paper of heat roll fixing device in image forming apparatus using electrophotography - Google Patents

Abstract

(57) [Abstract] [Purpose] A heat roll for an image forming apparatus using electrophotography, which has a simple structure and can prevent the oil attached to the heat roller from being transferred to a fixing recording paper. An oil transfer prevention mechanism on the recording paper of the fixing device. A heat roller 30H can be located in a fixing position where it comes into pressure contact with a press roller 30P and a retracted position that is a predetermined amount above the fixing position, and a heat roller gear 38 fixed to the side end at the retracted position. Engages with the gear 46 of the retracting heat roller drive system 41 linked to the motor 10, disengages at the fixing operation position, is rotationally driven by the rotation of the motor 10 at the retracting position, and stops by disengagement when returning to the fixing operation position. To do.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a heat roll fixing device used in an electrophotographic image forming apparatus, and more particularly, to an electrophotographic image forming apparatus configured to retract a heat roller from a working position during standby. It relates to a mechanism for preventing oil transfer to the recording paper of the heat roll fixing device.

[0002]

[Prior Art]

 Conventionally, a photoreceptor on the surface of a photosensitive drum is exposed to form a latent image, a toner is attached to the latent image for development (toner image formation), and this toner image is transferred to a recording sheet, and at the same time, a fixing device is formed. A so-called electrophotographic method of fixing by means of a known method is known, and as one of image forming apparatuses utilizing such an electrophotographic method, an image is formed on the same continuous recording paper as that used in a conventional line printer. There is an electrophotographic printer that does. The same continuous recording paper used in line printers is folding continuous paper with feed holes (hereinafter simply referred to as continuous paper), so-called fan-hold paper, and the folded parts are easily perforated. It is configured so that it can be disconnected.

By the way, in an image forming apparatus using a conventional general electrophotographic method such as a copying machine, as a method of fixing a toner image on a recording sheet, an unfixed recording sheet is set on a heated roller (heat roller). In many cases, so-called heat roll fixing is used in which the toner is heated and fused by abutting and pressing and heat applied from the heat roller. In heat roll fixing, a heat roller that is heated to a high temperature and a press roller are installed in parallel and adjacent to each other to form a fixing roller pair, and by sandwiching the recording paper between the fixing roller pair, the recording paper is pressed against the heat roller. Since it is heated by heating, it has an advantage of high thermal efficiency and high speed. Usually, the heat roller is rotationally driven, and the fixing device can also drive the conveyance of the recording paper.

Here, when this heat roll fixing is adopted in the electrophotographic printer that uses continuous paper as the above-mentioned recording paper, the recording paper (continuous paper) becomes a heat roller and a pressing roller while waiting for printing (image formation). If the same part of the recording paper is pinched by the heat roller (that is, in the fixing operation state), the heat applied from the heat roller causes a problem such as burning or blistering. If possible, prevent the recording paper from contacting the heat roller during printing standby (during fixing), and at the start of printing (at the start of fixing operation), the front edge of the toner image is transferred by the rotation of the photosensitive drum after the start of image formation. The heat roller is returned to the fixing operation position slightly before the start of the image formation, and at the same time, the toner image is rotationally driven or fixed in synchronization with the front end of the toner image reaching the transfer portion after the start of image formation. A configuration is considered in which the action and the recording paper conveyance are started.

[0005]

[Problems to be solved by the device]

 By the way, in the heat roll fixing device, a cleaner in which a fibrous member such as felt is impregnated with a release agent such as silicone oil is used to clean the heat roller in order to clean the toner adhered to the surface of the heat roller and prevent the fusion. Abuttingly arranged. Here, in the fixing device configured such that the heat roller retracts from the fixing operation position during the fixing standby as described above, the rotation of the retracted heat roller is stopped, but at the time of the stop (that is, the fixing standby). Since the cleaner is kept in contact with the same position of the heat roller for a long time, the oil oozes out from the cleaner and partially adheres to the outer peripheral surface of the heat roller, and this oil is transferred to the fixing recording paper at the start of fixing action. There was a problem that the recording paper was stained.

For this reason, the applicant has previously established a clutch on the heat roller side of the drive system that drives the tractor and the heat roller by the same drive source, and independently inherits the driving force to the heat roller. The heat roller is driven to rotate for a specified time immediately before returning to the fixing position, and then stopped, so that the oil that oozes out from the cleaning felt and adheres to the outer peripheral surface of the heat roller becomes the cleaning felt. Therefore, we proposed a structure that can be absorbed or spread over the entire outer surface to prevent the adhered oil from being transferred to the fixed recording paper. However, this structure requires a clutch and the control becomes complicated. was there.

[0007]

[The purpose of the device]

 In view of the above circumstances, the present invention provides an image forming apparatus using electrophotography, which has a simple structure and can prevent the oil attached to the heat roller from being transferred to the fixing recording paper. The purpose of the present invention is to provide an oil transfer prevention mechanism for recording paper of a heat roll fixing device.

[0008]

[Means for solving the problem]

 In order to achieve the above object, an oil transfer preventing mechanism for a recording sheet of a heat roll fixing device in an image forming apparatus using an electrophotographic method according to the present invention has a driving force transmission system for transmitting a driving force from a driving source. A tractor that can drive the recording paper through the heat roller and a heat roll A recording paper transport drive mechanism that is configured to rotate the heat roller of the fixing device is provided. In the device configured to retreat from the retreat heat roller drive system, the retreat heat roller drive system that transmits the driving force from the retreat heat roller drive source drives the heat roller at the retreat position and the heat roller so that the heat roller can be driven. It is provided to release the linkage at the fixing position, and the heat roller retracts before returning from the retracted position of the heat roller to the fixing position. It is configured to be rotationally driven via the save heat roller drive system by Torora driving source.

[0009]

[Example of device]

 Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a schematic structure of a drive mechanism of a fixing device of an electrophotographic printer using fan-hold paper as recording paper to which the present invention is applied, and FIG. 2 shows a state in which a heat roller retracting drive system 41 is removed. It is a top view. The drive mechanism of the fixing device shown in the figure transmits a rotational force from a motor gear 11 fixed to a spindle of a motor 10 serving as a drive source to a gear 14 mounted on a shaft 13 via a gear 12 and also from the shaft 13 Is a tractor drive system 21 that transmits a rotational force to the tractor 20 that drives the recording paper, and a fixing device drive system 31 that transmits a rotational force to the fixing device 30 are linked independently of each other. It is composed of Although not shown, a drive system reaching the photosensitive drum is linked to the motor gear 11, and the motor 10 also serves as a rotation driving means for the photosensitive drum. In other words, the motor 10 is a rotation drive source for the photosensitive drum and a drive source for the tractor 20 and the fixing device 30, and also serves as a drive source for a retract heat roller drive system 41 described later.

The fan-hold paper is driven to be conveyed by a fixing device 30 which will be described later, and when the fan-hold paper is set, the tip of the tractor 20 corresponds to the fixing operation position of the fixing device 30 (conveyance by the fixing device 30). The rotation speed is set to be slightly slower than the conveyance speed of the fan-hold paper by the fixing device 30, and at the time of normal image formation (fan-hold paper conveyance). At the time), the fan hold paper conveyed and driven by the fixing device 30 is configured to allow the driven circulation.

The gear 14 is attached to the shaft 13 via an electromagnetic clutch 15 as a clutch means. When the clutch 15 is engaged, the gear 14 rotates to drive the shaft 13 to rotate. When the engagement is released, the gear 14 idles so that the rotational driving force is not transmitted to the shaft 13. That is, the transmission / reception of the rotational force to both the tractor drive system 21 and the fixing device drive system 31 can be intermittently operated by the intermittent operation of the clutch 15. A timing pulley 32 for inputting a rotational force to the fixing device drive system 30 is fixed to the shaft 13 so as not to rotate relative to it, and a tractor gear 22 of the tractor drive system 21 is fixed to be unable to rotate relative to the shaft 13.

In the tractor drive system 21, a tractor gear 22 meshes with an input gear 23 fixed to a shaft 25 provided with one pulley 24 that links the tractor 20, and rotation of the shaft 13 causes the tractor gear 22 and the Rotational force is transmitted via the input gear 23, and the tractor 20 is driven to rotate. Although not shown, the pulley 24 is provided on the shaft 25 via a one-way clutch, and the action of the one-way clutch allows the tractor 20 to idle in a direction in which the tractor 20 rapidly rotates in its orbital drive direction (fan hold paper conveyance direction). Is becoming That is, by the action of the one-way clutch, the tractor 20 can be rotated by being driven by the fan-hold paper that is conveyed and driven by the fixing device 30 as described above.

The fixing device drive system 31 has a timing belt 34 connected between a timing pulley 32 and a pulley 33 on the fixing device 30 side, and a pulley gear 36 coaxially connected to the pulley 33 via a one-way clutch 35. The idle gear 37 meshes with the heat roller gear 38 fixed to the end of the heat roller 30H of the fixing device 30. The one-way clutch 35 is engaged with the counterclockwise rotation of the pulley 33 indicated by an arrow in the drawing, and the pulley gear 36 is driven to rotate, and is not engaged with the counterclockwise rotation of the pulley 33 and idles with respect to the pulley gear 36. The counterclockwise rotation of the timing pulley 32 is transmitted through the timing belt 34, the pulley 33, the one-way clutch 35, the pulley gear 36, and the idle gear 37 to the heat roller gear 38 (immediately). The heat roller 30H) is driven to rotate counterclockwise in the figure, and even if the heat roller 30H is rotated in the same direction, the one-way clutch 35 acts on the pulley 33 from the heat roller gear 38 (that is, the heat roller 30H) side to rotate it. It is not transmitted. Incidentally, reference numeral 39 in the figure denotes a tension pulley for applying a predetermined tension to the timing belt 34.

Further, a retract heat roller drive system 41 is linked to the gear 14. In the retract heat roller drive system 41, a gear 44, which is integrally provided coaxially with a pulley 43, meshes with an upper side of the gear 14, and the pulley 43 and a gear 46 arranged at a predetermined upper position of the fixing device 30 are coaxial with each other. The timing belt 47 is stretched between the pulley 45 and the pulley 45, which are integrally provided with the gear. The rotation of the gear 14 (that is, the rotation of the motor 10) causes the timing belt 47 to pass through the gear 44, the pulley 43, and the timing belt 47. The pulley 45 (that is, the gear 46) is rotationally driven. The gear 46 is arranged at a position where the heat roller gear 38 fixed to the side end of the heat roller 30H of the fixing device 30, which will be described later, is just meshed with the heat roller 30H.

The motor 10 and the clutch 15 are operated and controlled by a control device (not shown) of the electrophotographic printer including the fixing device 30. The rotation of the motor 10 drives the photosensitive drum to rotate and simultaneously. The driving force is transmitted to the evacuation heat roller driving system 41, and the transmission of the driving force to the tractor driving system 21 and the fixing device driving system 31 can be interrupted by operating the clutch 15 when the motor 10 is rotating. Immediately, while the photosensitive drum is rotating, the retract heat roller drive system 41 is driven, and independently of this, the tractor drive system 21 and the fixing device drive system 31 can be driven or stopped. ..

In the image forming apparatus using the electrophotographic method, the operating parts such as the exposing part, the developing part, and the transferring part are arranged around the photosensitive drum, and each process is performed as the photosensitive drum rotates. With the above structure, the image forming start position of the recording paper is made to coincide with the transfer portion, and the recording paper is conveyed when the exposed portion of the photosensitive drum reaches the transfer action portion facing the recording paper by the rotation of the photosensitive drum. By starting it, it becomes possible to form an image from a predetermined position on the recording paper.

As shown in a perspective view of FIG. 3 and a sectional view taken along line AA of FIG. 4, the fixing device 30 includes a pair of fixing rolls in which a heat roller 30H and a press roller 30P are arranged one above the other in FIG. A heat roller 30H supported by a holder 50, which is arranged so as to be orthogonal to the conveyance direction of the fan hold paper 20 shown by the arrow and is swingable around a shaft 51 which is the rotation center of the idle gear 36 as a fulcrum. Is urged by a predetermined pressing force to the lower press roller 30P to reach the fixing position (state shown in the drawing), and heat is generated by the counterclockwise swinging around the shaft 51 of the holder 50 in the figure. The roller 30H can be set in a retracted state in which it is separated from the press roller 30P. In the figure, 30C is a cleaning felt.

The upper heat roller 30H is a cylindrical roller in which a heating element such as a halogen lamp is inserted, and is heated to a predetermined temperature by the heating element. Both ends thereof are supported by a holder 50 pivotally mounted on the chassis 1 by a shaft 51 so as to be capable of swinging relative to the chassis 1. Although not shown in FIGS. 3 and 4, the above-mentioned heat roller gear 38 is fixed to one side end, and the rotational force transmitted through the fixing device drive system 31 causes the heat roller gear 38 to pass through the heat roller gear 38. It is designed to be driven to rotate. The lower press roller 30P is formed by forming an elastic member layer such as silicone rubber having a predetermined hardness having heat resistance around a core metal, and rotatably supported at a predetermined position of the chassis 1 (the supporting structure is shown in FIG. (Not shown).

The holder 50 for supporting the heat roller 30H has a length substantially the same as that of the heat roller 30H and arm portions 50B extending from both ends of the connecting portion 52A located above the heat roller 30H to the fan hold paper 20 introduction side. It is provided and is pivotally supported on the chassis 1 by a shaft 51 at substantially the center of the arm portion 50B. In addition, a spring receiver 50C is formed at the tip of the arm portion 50B. The spring receiver 50C is formed by bending the upper side portion raised upward toward the inside (center side of the apparatus). Inside the left and right arm portions 50B, a lever 52 is swingably supported by the same shaft 51 that pivotally supports the arm portions 50B (that is, the holder 50).

The lever 52 is pivotally supported by a shaft 51 substantially at the center in the longitudinal direction, and a cam follower 53 is rotatably provided at the tip of one side (fan hold paper 20 introduction side) of the lever 52. Further, a spring holding portion 52A is provided at a lower side portion of the holder 50 corresponding to the spring receiver 50C at a lower side portion so as to be bent and protruded outward (toward the arm portion 50B), and a shaft 51 of the spring holding portion 52A is provided. A hook 52B is provided so as to be bent adjacent to the side and bent outward.

As shown in FIG. 4, a torsion spring 54 (not shown in FIG. 3 for the sake of complexity) is externally inserted between the arm portion 50 B of the holder 50 of the shaft 51 and the lever 52. One of the extending ends of the torsion spring 54 is located above the hook 52B of the lever 52, and the other end is in contact with the lower surface of the hook portion 1A formed by bending the upper side of the chassis 1 inward, so that the torsion spring 54 can be restored. The lever 52 is urged to oscillate counterclockwise in FIGS. 1 and 4, and the cam follower 53 attached to the end of the lever 52 is placed on the outer peripheral cam surface of the eccentric cam 2 located below the cam follower 53. I am supposed to contact you.

A coil spring 55 is interposed between the spring receiver 50C of the holder 50 and the spring holding portion 52A of the lever 52, and the holder 50 is rotated clockwise relative to the lever 52 by the urging force of the coil spring 55. The rocking restricting bolt 56 fixed to the spring holding portion 52A through the spring receiver 50C is rocked and biased (that is, in the direction in which the holding side of the heat roller 30H faces downward) and faces the lever 52. The relative swing amount of the holder 50 (on the side where the angle between the two is widened) is regulated. That is, the lever 52 is oscillated and urged counterclockwise in FIG. 4 by the torsion spring 54 so that the cam follower 53 contacts the eccentric cam 2 and is oscillated and driven according to the displacement of the outer peripheral cam surface due to the rotation of the eccentric cam 2. At the same time, the holder 50 is adapted to swing together with the swing of the lever 52 via the coil spring 55 or the swing regulation bolt 56.

Then, as shown in FIG. 4, when the cam follower 53 is in contact with the position where the displacement of the outer peripheral cam surface of the eccentric cam 2 from the center of rotation is largest (the state where the cam follower 53 is located on the uppermost side), the heat roller 30H Of the press roller 30P comes into contact with the outer periphery of the press roller 30P, and the lever 52 swings after the contact of the heat roller 30H with the press roller 30P, so that the coil spring 55 is compressed and deformed by a predetermined amount to restore the coil spring 55. Then, the heat roller 30H is brought into pressure contact with the press roller 30P with a predetermined pressing force to enter the fixing operation state. On the other hand, when the cam follower 53 is in contact with the position where the displacement of the outer peripheral cam surface of the eccentric cam 2 from the rotation center is the smallest (the state where the cam follower 53 is located at the lowermost side), the lever 52 swings counterclockwise in the figure. The holder 50 is interlocked with the movement through the rocking restricting bolt 56, and the heat roller 30H held by the holder 50 is at the retracted position, which is apart from the press roller 30P by a predetermined distance as shown in FIG.

The eccentric cam 2 is non-rotatably fixed to a cam shaft 2A that is rotatably supported by a chassis (not shown) of an electrophotographic printer including the heat roll fixing device 30. 2A is rotatably driven by a drive source (not shown) which is driven and controlled by a control device (not shown) of the electrophotographic printer, and at the time of printing (at the time of image formation), a predetermined pressing force is applied to the heat roller 30H as shown in FIGS. The press roller 30P is pressed to the fixing action position, and the heat roller 30H is controlled so that the heat roller 30H is in the retracted position above the press roller 30P as shown in FIG.

Here, the heat roller gear 38 fixed to the side end of the heat roller 30H transmits the driving force to the gear 46 of the retract heat roller drive system 41 in the state where the heat roller 30H retracts upward as described above. This meshing is possible, and when the heat roller 30H returns to the fixing operation position, this meshing state is released. Since the retracting of the heat roller 30H (the swinging of the holder 50) is performed around the shaft 51, which is the rotation center of the idle gear 37 of the fixing device drive system 31, the fixing device drive system 31 is operated by the heat roller 30H. It is in the linked state regardless of whether it is in the retracted position or the fixing operation position.

In the fixing device 30 configured as described above, the lever 52 and the holder 50 are swingably driven by the rotation of the eccentric cam 2 as described above, and at the time of printing, the heat roller 30H is used as the fixing action position to perform the fixing action. When printing is on standby, it is retracted by a predetermined amount. At the fixing operation position, the heat roller 30H is pressed and pressed by the press roller 30P with a predetermined pressing force, and the heat roller 30H is rotationally driven to pressurize and heat the fan hold paper 20 sandwiched between the rollers 30H and 30P. Then, while performing the fixing action, the fan hold paper 20 is conveyed and driven to be discharged.

That is, when the image formation is started from the print standby state in which the heat roller 30H shown in FIG. 5 is in the retracted state, as shown in the timing chart of FIG. 6, the image of the recording paper (fan hold paper) is From the state where the formation start position coincides with the transfer portion and is stopped, the motor 10 is rotated with the clutch 15 disengaged to rotate the photosensitive drum, and after a predetermined time, exposure is started and the eccentric cam 2 is rotated. Then, the heat roller 30H is returned to the fixing state, and at the same time when the exposed portion of the photosensitive drum reaches the transfer action portion facing the recording paper by the rotation of the photosensitive drum (predetermined from the start of exposure. Time: after T), the clutch 15 is engaged. As a result, the tractor 20 and the heat roller 30H are driven through the tractor drive system 21 and the fixing device drive system 31 to start the conveyance of the recording paper (fan hold paper), and the recording paper (fan hold paper) is started from the photosensitive drum. The transfer of the toner image to (4) and the fixing action by the heat roller fixing device 30 are performed.

Here, the heat roller 30H in the retracted position has its heat roller gear 38 linked to the retracted heat roller drive system 41 and rotates when the motor 10 starts rotating, but retracts due to the rotation of the eccentric cam 2. While returning from the position to the fixing operation position, the heat roller gear 38 disengages from the gear 46 of the retract heat roller drive system 41, and stops. When the latch 15 is continued, it is rotationally driven via the fixing device drive system 31.

That is, the heat roller 30H in the retracted state is rotationally driven simultaneously with the start of rotation of the motor 10 via the retractable heat roller drive system 41, stops in the middle of returning to the fixing position, and stops in the fixing operation position. As described above, the heat roller 30H is rotationally driven for a predetermined period of time before the fixing operation is started, so that the heat roller 30H oozes from the cleaning felt 30C to the outer peripheral surface of the heat roller 30H. The adhering oil is absorbed by the cleaning felt 30C or spread over the entire outer peripheral surface, and the adhering oil is prevented from being transferred to the fixing recording paper (fan hold paper) after the start of the fixing operation. When the heat roller 30H in the retracted position is rotationally driven via the retracted heat roller drive system 41, the rotational force of the heat roller 30H is transmitted to the fixing device drive system 31 via the heat roller gear 38, the idle gear 37, and the pulley gear 36. Although transmitted in reverse, the pulley 33 does not rotate due to the action of the one-way clutch 35, and therefore the tractor 20 is not driven by the tractor drive system 21 to move the recording paper.

In the above-described embodiment, the tractor drive system 21 and the fixing device drive system 31 are connected to each other via the motor 10 which is the rotational drive source of the photosensitive drum via the clutch 15 and the motor 10 is being driven (the rotation of the photosensitive drum). A structure in which the tractor drive system 21 and the fixing device drive system 31 are driven by engaging the clutch 15 in the middle (namely, the motor 10 drives the photosensitive drum, the tractor 20, the fixing device 30, and the retract heat roller). However, the present invention is not limited to this configuration, and the drive sources of the tractor 20 and the fixing device 30 (the tractor drive system 21 and the fixing device drive system 31) are used as the drive source of the photosensitive drum. It may be provided separately, or may be appropriately changed by providing an independent drive source for the retract heat roller drive system 41.

Next, an embodiment in which the drive sources of the tractor 20 and the fixing device 30 (the tractor drive system 21 and the fixing device drive system 31) are provided separately from the drive source of the photosensitive drum will be described with reference to FIGS. 7 to 9. To do. FIG. 7 is a schematic configuration diagram of the drive mechanism, FIG. 8 is a plan view showing a state in which the heat roller retracting drive system 41 is removed, and FIG. 9 is a plan view of the heat roller retracting drive system 41. The input gear 28 of the tractor drive system 21 and the idle gear 37 of the fixing device drive system 31 mesh with the drive gear 61 fixed to the spindle of the motor 60, and the tractor is turned ON / OFF by the motor. The rotational force is transmitted to the drive system 21 and the fixing device drive system 31 (that is, the orbital drive of the tractor 20 and the rotational drive of the heat roller 30H are performed). The input gear 28 is fixed to a shaft 26 provided with one pulley 27 that links the tractor 20. Further, the pulley 27 has a structure in which the tractor 20 is driven in its orbital drive direction (fan hold paper conveyance direction) as in the above-described embodiment. ) Is mounted on the shaft 26 via a one-way clutch (not shown) so that it can rotate in the direction of faster rotation.

In the heat roller retracting drive system 41, the gear 46 is arranged at a position where the heat roller gear 38 meshes when swinging and retracting, as in the above-described embodiment. The photosensitive drum (not shown) is rotationally driven via the gear 12. The motor 10 is driven by the rotation of the motor 10 (that is, in synchronization with the rotation of the photosensitive drum) in cooperation with the motor gear 11 fixed to the spindle of the motor 10 which is a drive source. It has become so. With the above configuration, when the heat roller 30H is in the retracted state and the image formation is started from the print standby, the rotation of the motor 10 (rotation of the photosensitive drum) is performed before the heat roller 30H returns to the fixing state. The heat roller 30H is rotationally driven through the retract heat roller drive system 41, and the adhering oil is wiped by the cleaning felt 30C. The rotation of the heat roller 30H is stopped by the disengagement of the heat roller gear 38 and the gear 46 of the retract heat roller drive system 41 during the return from the retracted position to the fixing position, and the heat roller 30H is in this stopped state. Then, it is pressed against the press roller 30P, and then rotated by the rotation of the motor 60 through the fixing device drive system 31.

[0033]

[Effect of the device]

 As described above, according to the present invention, it is possible to rotate the heat roller for a predetermined time before returning to the fixing operation position before starting the fixing operation with a simple structure, whereby the heat roller oozes out from the cleaning felt. The oil adhering to the outer peripheral surface of the roller can be absorbed by the cleaning felt or spread to the entire outer peripheral surface to prevent the oil adhering to the fixing recording paper after the fixing operation is started.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a drive mechanism of a fixing device of an electrophotographic printer to which the present invention is applied.

FIG. 2 is a plan view showing a state in which a retract heat roller drive system is removed from FIG.

FIG. 3 is a perspective view showing a swing-back structure of a heat roller.

4 is a sectional view taken along line AA of FIG.

FIG. 5 is a diagram showing a state where the heat roller is moved to the retracted position from FIG. 1.

[Fig. 6] Operation time chart

FIG. 7 is a schematic configuration diagram of a drive mechanism of a fixing device according to another embodiment of the present invention.

FIG. 8 is a plan view showing a state in which a drive system for retracting the heat roller is removed from FIG.

FIG. 9 is a plan view of a drive system for retracting the heat roller.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Motor (drive source: rotation drive source of photosensitive drum: retract heat roller drive source) 15 ... Clutch (clutch means) 20 ... Tractor 21 ... Tractor drive system (driving force transmission system) 30 ... Fixing device (heat roll fixing device) ) 31 ... Fixing device drive system (driving force transmission system) 30H ... Heat roller 41 ... Retraction heat roller drive system 60 ... Motor (drive source)

Claims (3)

[Scope of utility model registration request] 1. A recording sheet conveying device configured to rotate and drive a tractor capable of conveying a recording sheet and a heat roller of a heat roll fixing device via a driving force transmission system for transmitting a driving force from a driving source. In the one having a drive mechanism and configured such that the heat roller is retracted from the fixing operation position by the retract drive means during the standby for fixing, the retract heat roller drive system for transmitting the driving force from the retract heat roller drive source, The heat roller at the retracted position and the heat roller are provided so as to be drivably linked with each other and the heat roller is released so as to release the link at the fixing operation position.
Prior to the return of the heat roller from the retracted position to the fixing operation position, the heat roller is configured to be rotationally driven by the retract heat roller drive source via the retract heat roller drive system. A mechanism for preventing oil transfer to a recording paper of a heat roll fixing device in an image forming apparatus utilizing electrophotography. 2. A retracting heat roller driving source is a rotary driving source of a photosensitive drum which is driven prior to the returning of the heat roller from the retracted position to the fixing operation position, and the heat roller in the retracted position is the photosensitive drum. 2. The heat roll fixing in the image forming apparatus using the electrophotographic method according to claim 1, wherein the rotary drive source is rotationally driven through the retracting heat roller drive system. Mechanism to prevent oil transfer to the recording paper of the device. 3. A drive source for the tractor and the heat roller of the heat roll fixing device is a rotary drive source for the photosensitive drum which is driven prior to the return of the heat roller from the retracted position to the fixing operation position, and its drive source. Clutch means capable of interrupting the transmission of rotational force is interposed in the force transmission system, and the clutch means is configured to rotationally drive the tractor and the heat roller at a predetermined timing with the rotation of the photosensitive drum. An oil transfer preventing mechanism for a recording paper of a heat roll fixing device in an image forming apparatus utilizing the electrophotography according to claim 2.