JP3195523B2 - Image forming apparatus having moving member whose moving speed is controlled - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, and more particularly, to forming an image on a photosensitive drum and
The present invention relates to an image forming apparatus that once transfers an image to an intermediate transfer member and then transfers the image to a recording medium.

[0002]

2. Description of the Related Art Conventionally, a cylindrical intermediate transfer drum is constructed by surrounding a sheet-like transfer member in a cylindrical shape, and a secondary transfer roller 12 and a cleaner 11 provided downstream of the roller are connected to the intermediate transfer drum. An apparatus arranged to be separated from the outer surface of the drum, and if necessary, brought into contact with the outer surface to perform transfer to recording paper and removal of residual toner is disclosed in JP-A-6-161292.
No. 6,098,045.

In order to press or move the moving member such as the cleaner and the secondary transfer drum to and from the outer surface of the intermediate transfer drum, the moving member is pressed by a cam mechanism to make contact with the outer surface or to move the cam mechanism. A mechanism for following and contacting the outer surface, or a mechanism for pressing the outer surface by urging the moving member in a direction of pressing the outer surface and releasing a clutch, and further, a motor for moving the moving member And a mechanism for pressing against the outer surface by the driving force of the motor.

[0004]

However, as described above, according to the prior art, the mechanism using the cam mechanism turns off the power when a trouble occurs due to the jam of the recording transfer paper. It is necessary to remove the transfer paper and return the cam to the initial position. For that purpose, it is required to turn on the power again and to reversely drive the cam mechanism. This reverse drive affects the life of the device.

In the above-described mechanism using a clutch and a mechanism driven by a motor, since the moving member travels by an urging force or a motor driving force, an impact sound and an impact force become problems. And the like, and the vibration at the time of absorbing the shock by the damper causes a time loss until stable pressing, or the temporal deformation of the damper disturbs the timing at which the moving member comes into contact with the outer surface.

In view of the above circumstances, it is an object of the present invention to provide an image forming apparatus which does not give an impact to an outer surface of an intermediate transfer member when the moving member contacts the outer surface. Also,
Another object of the present invention is to provide an image forming apparatus in which no time loss occurs until a movable member is stably pressed against an intermediate transfer member. It is another object of the present invention to provide an image forming apparatus capable of accurately controlling the position at which the moving member presses the intermediate transfer member. Another object of the present invention is to
An object of the present invention is to provide an image forming apparatus with improved durability.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an image forming apparatus having an intermediate transfer drum and a moving member which comes into contact with and separates from the outer surface of the drum. A moving member that contacts the outer surface of the drum and presses the outer surface, and that the moving member is separated from the outer surface against the urging force and released, and the traveling member travels by releasing the moving member. A one-way rotation driving member connected to the moving member and receiving a rotation driving force only in one direction from a rotation driving source; and a one-way rotation driving member provided on the one-way rotation driving member. A one-way clutch configured such that the moving member follows the moving direction in a turning direction, and the moving member is freely movable in a counter-rotating direction of the one-way rotation driving member; By The moving member is configured such that the moving member in accordance with the rotation of the one-way rotary drive member approaches the is speed controlled external surface.

[0008] As shown in FIG.
The holding member 62 having the cleaning blade 63 constituting the cleaner portion 13 having a biasing force by the spring 68 toward 6 acts as a moving member that comes into contact with the outer surface 26 of the drum and presses the outer surface. This holder 62
The cleaning blade 63 and the intermediate transfer sheet 26, which is the outer surface of the intermediate transfer drum, are held apart from each other at the initial position by being connected to the plunger 66A via the rack 65A.

A gear 41 connected to a driving source transmits a driving force to a shaft 70 via a gear 71. The shaft 70 serves as a one-way rotation driving member that rotates only in one direction. In FIG. 8, the rotation is clockwise. The gear 42 into which the shaft 70 is inserted is
When a one-way clutch is interposed between the shaft and the shaft 70 and the shaft 70 is stopped at the initial position, the shaft 70 freely rotates clockwise. When an electric signal comes into the plunger 66A while the shaft 70 is rotating, the rack 65A by the plunger
Is released, and the rack 65A attempts to move rightward by the urging force of the spring 68.

When the shaft 70 is stopped, the gear 42 is prevented from rotating clockwise. However, when the shaft 70 is rotating clockwise, the gear 42 follows the rotation of the shaft 70 and rotates clockwise. Rotate. Therefore, the rack 65A also moves to the right. This axis 7
When the rotation speed of the rotation 0 is sufficiently reduced from the driving source, the holding member 62 connected to the rack 65A is controlled by the speed of the shaft 70 to move, and the cleaning blade 63 generates an impact on the intermediate transfer sheet 26. Hold down and touch. Therefore, the one-way rotation driving member and the one-way clutch constitute a moving speed control means. When the holding member is released, the moving member is controlled in speed by the moving speed control means to approach and contact the outer surface.

When an electric signal enters the plunger 66A while the cleaning blade 63 is in pressure contact with the intermediate transfer sheet 26, the plunger 66A is moved to the rack 65.
A is sucked, and the rack 65A moves to the left. At this time, even if the shaft 70 rotates clockwise, the gear 42 rotates counterclockwise without being restricted by the one-way clutch, and the cleaning blade 63 of the holder 62 separates from the intermediate transfer sheet 26 and initially moves. Return to position.

As shown in FIG. 9, a second transfer roller holding plate having a second transfer roller 19 constituting a recording paper transfer section 79 having a biasing force by a spring 69 toward the outer surface 26 of the intermediate transfer drum. 67 acts as a moving member that contacts the outer surface 26 of the drum and presses the outer surface. This holding plate 67 is connected to a plunger 66B via a rack 65B.
At the initial position, the second transfer roller 19 and the intermediate transfer sheet 26, which is the outer surface of the intermediate transfer drum, are held apart from each other.

A gear 49 connected to a driving source transmits a driving force to a shaft 74 via a gear 73. The shaft 74 functions as a one-way rotation driving member that rotates only in one direction. The rotation is counterclockwise in FIG. Gear 50 for inserting shaft 74
When a one-way clutch is interposed between the shaft 74 and the shaft 74, the shaft 74 freely rotates counterclockwise when stopped at the initial position. When the shaft 74 is rotating, the plunger 66
When an electric signal arrives at B, the rack 6 by the plunger
The lock of 5B is released, and the rack 65B tries to move rightward by the urging force of the spring 69.

When the shaft 74 is stopped, the gear 50 is prevented from rotating counterclockwise. However, when the shaft 74 is rotating counterclockwise, the gear 50 follows the rotation of the shaft 74 and rotates counterclockwise. Rotate clockwise. Therefore, the rack 65B also moves to the right. When the rotation speed of the shaft 74 is sufficiently reduced from the driving source, the second transfer roller holding plate 67 connected to the rack 65B moves while being regulated by the speed of the shaft 74, and the second transfer roller 19 The intermediate transfer sheet 26 contacts the intermediate transfer sheet 26 while suppressing the occurrence of impact. Therefore, the one-way rotation driving member and the one-way clutch constitute a moving speed control means. When the holding member is released, the moving member is controlled in speed by the moving speed control means to approach and contact the outer surface.

The second transfer roller 19 is used as an intermediate transfer sheet 26
When an electric signal enters the plunger 66B in a state where the plunger 66B is in pressure contact with the plunger 66B, the plunger 66B sucks the rack 65B and moves leftward in the rack 65B. At this time, even if the shaft 74 rotates counterclockwise, the gear 50 rotates clockwise without being restricted by the one-way clutch, and the second transfer roller 19 separates from the intermediate transfer sheet 26 and moves to the initial position. Return to.

With the above-described structure, when the moving member abuts on the outer surface of the intermediate transfer drum without using a special damper, the moving member does not give an impact to the outer surface. It is possible to provide an image forming apparatus with improved durability without causing a time loss until the moving member is stably pressed on the intermediate transfer drum.

Preferably, the moving member is adapted to a cleaning blade. As described above, when the moving member abuts on the outer surface of the intermediate transfer drum without using a special damper, the moving member does not apply an impact to the outer surface, and the moving member does not impact the intermediate transfer body due to vibration of the damper or the like. Since no time loss occurs until the stable pressing, the cleaner unit can be located closer to the recording transfer unit on the upstream side, and the apparatus can be downsized.

Preferably, the moving member is adapted to a recording paper transfer roller. As described above, when the moving member abuts the outer surface of the intermediate transfer drum without using a special damper, the outer member does not give an impact to the outer surface, and the moving member does not impact the intermediate transfer drum due to vibration of the damper or the like. Since no time loss occurs until the stable pressing, the image can be transferred to an accurate position on the recording paper in synchronization with the recording paper having a determined margin.

It is preferable that the moving member is a recording paper transfer roller and a cleaning blade, and the one-way rotation driving member connected to both is driven by the same driving source. If both are driven by the same drive source, the driving speed of both moving members can be regulated to a constant value even when the cleaner unit is located close to the recording transfer unit on the upstream side. The stable position can be controlled accurately.

Further, it is preferable that the recording paper transfer roller, the one-way rotation driving member connected to the cleaning blade, and the intermediate transfer drum are driven by a reduction gear train connected to the same driving source.
When the three members are driven by a reduction gear train connected to the same drive source, the moving speed of the intermediate transfer drum and the moving speed of the one-way rotation driving member correspond to the number of teeth of the gear, and the moving teeth of the intermediate transfer drum are changed. The number of rotations of the intermediate transfer drum with respect to the number thereof and the contact with the outer surface of the intermediate transfer drum can be accurately controlled.

Further, it is preferable that the holding means is a plunger so as to control suction, holding and release of the moving member by an electric signal. With this configuration, the moving member does not need to drive the drive mechanism or the like to return to the initial position, and can drive and return the plunger by an electric signal. The return is completed quickly. Therefore, when a trouble occurs due to a jam of the recording transfer paper, there is no need to reversely drive the moving member to return to the initial position by removing the transfer paper after the transfer paper is removed. Since the mechanism is not driven, the durability is improved.

Further, it is preferable that the holding means is configured to suck and hold the moving member in synchronization with a power supply cutoff. With this configuration, when the power is cut off due to a recording paper jam, a power failure, or the like, the moving member automatically returns to the initial position. Therefore, in the non-use state, the moving member is held in contact with the intermediate transfer sheet, so that the moving member or the intermediate transfer sheet is not deformed by the pressing of both and does not adversely affect image formation.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only.

FIG. 1 is an external view of an image forming apparatus to which the present invention is applied, FIG. 2 is a schematic view showing an intermediate transfer drum and a mechanism around the intermediate transfer drum, FIG. 4 is a view as viewed from the direction BB in FIG. 3, FIG. 5 is a configuration diagram of a roller disposed in the intermediate transfer drum, FIG. 6 is an operation diagram of a roller disposed in the intermediate transfer drum, 7 is a mechanism diagram of a cleaner unit and a recording paper transfer unit, FIG. 8 is a perspective view of the cleaner unit, FIG. 9, a perspective view of the recording paper transfer unit, FIG. 10 is a partially enlarged view of the cleaner unit, and FIG. FIG. 7 is an explanatory diagram of an operation of a cleaner unit.

As shown in FIG. 1, the image forming apparatus according to the embodiment of the present invention uses a light scanning system 1 comprising a polygon mirror 2, a lens system 3, etc. An electrostatic latent image is formed on photosensitive drums 9A and 9B via 5, 6 and 7, 8. The photosensitive drum 9A is provided with a yellow toner developing device 10A and a magenta toner developing device 10B, and the photosensitive drum 9B is provided with a cyan toner developing device 10C and a black toner developing device 10D. Have been.

The surfaces of the photosensitive drums 9A and 9B contact an intermediate transfer sheet 26 (external table) stretched on the intermediate transfer drum 11, and the intermediate transfer sheet has a volume resistivity of 10 6 to 10 12.
A resistor in a medium resistance region of Ωcm, which is formed of polycarbonate, polyimide, polyetheretherketone, or the like having a thickness of about 1 mm.

The photosensitive drums 9A and 9B are developed one by one from the developing device for each rotation of the drum, and are transferred to the intermediate transfer sheet 26 of the intermediate transfer drum 11 by Coulomb force. When the transfer of one color is completed, the toner is removed from the photosensitive drum by a cleaner mechanism (not shown), and then the other color is developed on the photosensitive drum. Specifically, yellow is transferred from the photosensitive drum 9A to the intermediate transfer sheet 26,
Thereafter, the intermediate transfer sheet 26 rotated to the position of the photosensitive drum 9B is transferred with cyan from the photosensitive drum 9B.

After transferring the yellow color of the intermediate transfer sheet 26 to the photosensitive drum 9A, the residual toner is removed with a cleaner.
Develop magenta color and apply the magenta color to the intermediate transfer sheet 2
Transfer to No. 6. Similarly, after transferring the cyan color also on the photosensitive drum 9B, the residual toner is removed by a cleaner, and the transfer is performed by developing the black color.

When the four color toners are transferred to the intermediate transfer sheet 26, the paper accommodated in the paper cassette 14 passes through the passages 16 and 17 by the rollers 15 and the like, and the intermediate transfer sheet 26 and the second transfer roller 19 The toner that forms each image is transferred to the sheet, and the transferred sheet is discharged to the transfer device 20 and transferred to the fixing unit 22 by the transfer belt 21. In the fixing unit 22, the image is fixed by the fixing roller 23 and the pressure roller 24,
5 to the outside.

Next, the intermediate transfer drum 11 and its internal configuration will be described. FIG. 2 is a schematic view showing the intermediate transfer drum and a mechanism around the intermediate transfer drum. In the figure, a cylindrical intermediate transfer drum 11 is provided with an intermediate transfer sheet 26 surrounding the outer peripheral portion and in contact with the photosensitive drums 9A and 9B.
The end is fixed to the support 36.

The state will be described with reference to FIGS. FIG. 3 is a sectional view taken along line AA of FIG. 2, and FIG.
It is the figure seen from the B direction. As shown in FIG. 3, the intermediate transfer drum 11 formed in a cylindrical shape has flanges 29 at both ends of the cylindrical shape, and an opening hole 29b is opened at the center of the flange 29. The base 28 b of the shaft head 28 is rotatably fitted to the flange 29, and the flange 2
The vertical position of the flange 29 is regulated by the screw 31 of 8c.

A hole 28d is formed at the center of the shaft head 28,
The small-diameter ends 27a provided at both ends of the intermediate transfer drum shaft 27 are fitted into the holes 28d, and are fixed by screws 30. A gear 29a is cut out on the outer periphery of the flange 29,
The gear 29a is a gear 44 connected to the drive source 12 (FIG. 1).
(FIGS. 2 and 4). The shaft head 28 is fixed to a substrate portion of a device (not shown), and the flange 29 is configured to be rotatable around the shaft head 28 by receiving a driving force from the drive source 12.

3 and 4, a recess 29c is provided in the flange 29 near the gear 29a, and a support 36 is fixed to the recess 29c by a screw 32. Integrated by body 36. The intermediate transfer sheet 26 formed in a rectangular shape has a pressing plate 37 adhered to an end portion thereof with a double-sided tape 78,
The holding plate 37 is attached to the support 36 by fixing it with screws 32.

On the other hand, as shown in FIG. 2, backup auxiliary rollers 57A, 57A are provided inside the intermediate transfer drum 11.
B, backup rollers 58A to 58D, first transfer rollers 59A and 59B, and the like are provided to the intermediate transfer sheet 26 by shafts 53A to 53H with a predetermined pressing force.

The shafts 53A and 53D to which the backup auxiliary rollers 57A and 57B are attached, and the backup roller 58
The shaft 53G to which the C is attached and the shaft 53H to which the backup roller 58D is attached
1a is configured as a radial axis radiating outward from
A shaft 53B having a first transfer roller 59A provided in parallel with the shaft 53A near 3A; a shaft 53E having a first transfer roller 59B provided in parallel with the shaft 53D near the shaft 53D; The shafts 53C, 53F and the like to which 58A and 58B are attached are configured as non-radial shafts extending outward from a position away from the rotation center 11a of the intermediate transfer drum 11 to the right.

Axis 5 such as these radial axis and non-radial axis
3 is implanted on a shaft support 52 fixed to the intermediate transfer drum shaft 27 with screws 51 as shown in FIG.
A damper 55 formed of an elastic member such as rubber is adhered to the shaft 53. A shaft hole 56 b of a biaxial bearing 56 is slidably fitted to the shaft 53, and the biaxial bearing 56 is wound around the shaft 53. The roller 57A is urged by the coil spring 54 in the upper left direction in FIG. 3 so that the roller 57A presses the intermediate transfer sheet 26 with a predetermined pressing force at a position where the damper 55 contacts the biaxial bearing.

The configuration in which the shaft 53, the coil spring 54, the damper 55, and the roller 57 press the intermediate transfer sheet 26 with a predetermined pressing force includes a backup auxiliary roller 57B.
And the other rollers 58A-
58D and the first transfer rollers 59A and 59B have the same other configuration even though there is a difference in the predetermined pressing force pressing the intermediate transfer sheet 26.

Now, returning to FIG. 2 again, a cam 35 is provided on the support 36 inside the intermediate transfer drum 11. When the intermediate transfer drum 11 rotates clockwise, the cam 35 separates the rollers from the intermediate transfer sheet 26 and pushes down the rollers so that the rollers do not contact the support 36. As shown in FIG. 4, the cams 35 are provided one by one near the end of the support 36,
As shown in FIG. 3, the roller abuts on a stepped portion 57Ab having a larger diameter than the shaft portion 57Aa between the small-diameter shaft portion 57Aa fitted into the shaft hole 56a of the biaxial bearing 56 and the outermost portion of the roller. The roller is pressed down so as not to be in contact with the intermediate transfer sheet 26.

FIG. 5 shows the relationship between each roller and the cam 35 and the biaxial bearing 56. (A) shows the configuration of the roller 58D, in which the cam 35 is in contact with the step 58Db, and the support 36 is separated from the outer diameter of the roller 58D by a distance T.
(B) shows the configuration of the backup roller 58 and the first transfer roller 59, and the cam 35 has a stepped portion 59b (58Ab,
58Bb, 59Ab, 59Bb).
And the outer diameter of the roller are spaced from each other with an interval T. (C) shows the configuration of the backup auxiliary roller 57, in which the cam 35 is in contact with the stepped portion 57Ab (57Bb), and is separated from the support 36 by an interval T with the outer diameter of the roller 57.

Next, the operation of the embodiment constructed as described above will be described with reference to FIG. When the intermediate transfer drum 11 rotates clockwise, the lower side 35a of the cam 35 first contacts the step 57Ab of the roller 57A at an angle α57A where the line L1 forms the center line S1 of the shaft 53A. Then, as the cam 35 rotates, the lower side 35a of the cam 35 becomes a line L2.
As shown in (5), it moves while increasing the angle α57A.

As the cam 35 moves, the rollers 57
A descends as shown by a virtual line (dash-dot line),
The shaft 53B to which the transfer roller 59A is attached is a shaft 53a.
Roller 57A is in parallel with the roller 59A.
There is no contact with A. The lower side 35a of the cam 35 is L3
(Angle α59A), the stepped portion 5 of the roller 59A
9Ab comes into contact with the roller 57A and the roller 59A starts to descend. As the cam 35 moves, the rollers 57A
Starts rising from the lowest point indicated by a virtual line, and the lower side 3 of the cam 35
When 5a reaches the position of L4 (angle β57A), the cam 35
The lower side 35a starts to separate from the step 57Ab of the roller 57A.

At about the same time as L4, the roller 59A reaches the lowest point indicated by the imaginary line, and the lower side 35a of the cam 35 becomes L
5 (angle α58A). As the cam 35 moves, the roller 59A starts rising from the lowest point indicated by the imaginary line, and the lower side 35a of the cam 35 is at the position of L6 (angle β59A).
, The lower side 35a of the cam 35 starts to separate from the step portion 59Ab of the roller 59A. Almost at the same time as this L6,
The roller 58A reaches the lowest point indicated by the imaginary line, and as the cam 35 moves, the roller 58A starts rising from the lowest point indicated by the imaginary line, and the lower side 35a of the cam 35 is at the position L7 (the angle β).
58A), the lower side 35a of the cam 35 is
Withdrawal from the step 58Ab of A starts.

At about the same time as L7, the lower side 35a of the cam 35 contacts the step 57Bb of the roller 57B. Thereafter, the rollers 57B, 59B, and 58B perform the same operation as the rollers 57A, 59A, and 58A described above. As the cam 35 rotates, the lower side 35a of the cam 35 reaches the line L8 (angle α58C). As the cam 35 moves, the roller 58C reaches the lowest point indicated by the imaginary line, and as the cam 35 moves, the roller 58C starts rising from the lowest point indicated by the imaginary line, and the lower side 35a of the cam 35 is at the position L9 (angle). β58
When reaching C), the lower side 35a of the cam 35 starts to separate from the step 58Cb of the roller 58C.

As the cam 35 rotates, the lower side 35a of the cam 35 reaches the line L10 (angle α58D). As the cam 35 moves, the roller 58D reaches the lowest point indicated by the imaginary line, and as the cam 35 moves, the roller 58D starts rising from the lowest point indicated by the imaginary line and the lower side 35a of the cam 35
Reaches the position L11 (angle β58D), the lower side 35a of the cam 35 starts to separate from the step 58Db of the roller 58D.

As described above, in the present embodiment, the primary transfer roller 69 for transferring the latent image from the photosensitive drum 9 to the intermediate transfer sheet 26 is provided in the intermediate transfer drum 11, and is provided upstream of the transfer roller. A backup auxiliary roller 5 that is positioned to push the intermediate transfer sheet further toward the photosensitive drum
7. A backup roller 58 for satisfactorily rotating the intermediate transfer sheet 26 is provided. These rollers have a rotating shaft rotatably fitted to a bearing having an urging force by a spring toward the intermediate transfer sheet 26, and are interposed between the large-diameter portion contacting the intermediate transfer sheet 26 and the bearing. A step portion having a smaller diameter than the large diameter portion is provided.

On the other hand, a cam 35 is provided integrally with the intermediate transfer sheet in the intermediate transfer drum, and is rotated by rotation of the intermediate transfer drum so as to engage with the stepped portion and resist the urging force. , The plurality of rollers are sequentially separated from the intermediate transfer sheet by a predetermined amount in synchronization with the rotation of the intermediate transfer sheet.

Therefore, by appropriately selecting the shape of the cam for pushing down the roller, the pushing down depth,
In addition, the rotation angle of the intermediate transfer drum that contributes to pushing down can be set. Therefore, when it is not necessary to make contact with the intermediate transfer sheet, the durability of the roller can be improved by separating the roller from the sheet. Although the cam 35 is in contact with the step of the roller to push down the roller, the step may be pushed down.

Further, a support member 36 provided between two circular flanges is provided, and the end of the intermediate transfer sheet is surrounded by the support member 36 by surrounding the intermediate transfer sheet in a tubular shape. The roller is supported and fixed by the cam 35 so that the roller is separated from the support member 36 by a predetermined amount in a non-contact state in the rotation axis direction of the intermediate transfer drum. Even if the support member is located at the seam at the end of the intermediate transfer sheet without contacting the member, the rollers do not contact the support member, and the rollers are deformed to form an image. It does not adversely affect or reduce the durability of each roller.

Further, a plurality of rollers are formed as radial shafts 53A, 53D, 53G, and 53H having axial directions radially outward from the rotation center 11a of the intermediate transfer drum.
The non-radial shafts 53B, 53C, 53E, and 53F, each having an axial direction extending outward from a position deviated from the center of the rotation shaft, are respectively held, and the non-radial shafts adjacent to the radial shaft are both of them. The rollers are separated from each other as long as the rollers do not interfere with each other.

Therefore, the distance between the plurality of rollers can be set to the minimum distance. That is, if the arrangement of the two adjacent rollers is set so that they both slide in the radial direction with respect to the center of the rotation axis of the intermediate transfer drum, when both rollers are pushed down by the cams, they come close to each other. hand,
The outer periphery comes into contact. However, if one of the rollers is set to slide in the radial direction and the other is set to slide in the non-radial direction, when both rollers are arranged close to each other, when both rollers are pushed down, they do not approach each other, Or, they do not interfere when approaching. Therefore, more rollers can be arranged in a space-saving manner without increasing the outer diameter of the intermediate transfer drum, and the outer diameter of the rollers can be selected according to each application.

Further, since the non-radial shaft has a parallel non-radial shaft arranged in parallel with the adjacent radial shaft, even if both rollers are disposed close to each other, both rollers are disposed close to each other. When pushed down, do not approach each other. And since it is arranged in parallel with one of the adjacent radial axes, it does not approach the other adjacent radial axis until it escapes from the parallel state with the one radial axis, and further reduces the intermediate transfer body with a smaller diameter. It is possible to provide a small-sized image forming apparatus.

As shown in FIG. 6, the lower side 35a of the cam 35
Comes into contact with each roller at an angle α and leaves at an angle β. The angle of the penetrating contact can be made large if the axis of each roller is not a radial axis but a non-radial axis from a position shifted clockwise. By increasing the angle, the force applied to the shaft in the direction perpendicular to the shaft when the cam 35 contacts the step of each roller can be reduced, and the durability of the shaft is improved.

However, from the viewpoint of space saving, if all the shafts are non-radial shafts, if the rollers need to be arranged close to each other, the size is rather increased. Therefore, in that case, a combination of a radial axis and a non-radial axis is desirable. It is desirable that the contact and detachment of the roller and the cam 35 be performed between 60 ° and 120 ° in consideration of manufacturing and assembly errors between 62 ° and 115 °.

Further, the radial shaft and the non-radial shaft each having an elastic cushioning member on a head thereof, and a biaxial bearing having two shaft holes opened in a direction perpendicular to each other are provided, and one of the biaxial bearings is provided. One of the plurality of rollers is rotatably fitted in the shaft hole, and the radial shaft or the non-radial shaft is slidable by applying an urging force in the intermediate transfer sheet pressing direction to the other shaft hole. , So as to reduce the impact when the plurality of rollers press and return to the intermediate transfer sheet.

Therefore, the impact at the time when the roller comes back into contact with the intermediate transfer sheet is reduced by the elastic buffering member, and the vibration is suppressed as much as possible even if the plurality of rollers are successively and continuously separated from the intermediate transfer sheet. It is possible to provide an image forming apparatus that can provide an intermediate transfer member with less load fluctuation, can eliminate adverse effects on image formation, and have improved durability with less noise and noise.

Next, the configurations of the cleaner unit and the recording paper transfer unit according to this embodiment will be described. In FIG. 7, a cleaner unit 13 for removing residual toner on the intermediate transfer sheet 26
Is provided on the holder 62 so that the cleaning blade 63 can be brought into contact with and separated from the intermediate transfer sheet 26 of the intermediate transfer drum 11 so as to remove the residual toner on the intermediate transfer sheet 26 that has been transferred to the recording paper by the recording paper transfer unit 79. It is composed of

Then, the second transfer roller 19 of the recording paper transfer unit 79 and the cleaning blade 6 of the cleaner unit 13
In both cases, a pressing force is applied to the intermediate transfer sheet 26 by a spring, but the intermediate transfer sheet 26 is separated from the intermediate transfer sheet 26 and locked against the spring force by the action of the plunger. Is released, it approaches the intermediate transfer sheet 26 by the force of the spring. However, the approach speed by the spring is regulated by a reduction gear connected from the drive source 12, and the intermediate transfer sheet 26
It is configured to mitigate the impact on the vehicle. Hereinafter, this mechanism will be described.

In FIG. 7, the driving force from the driving source 12 (FIG. 1) is connected to a gear 38. Then, the driving force is further transmitted to the gears 38, 39, 40, 41 and the cleaner unit 13 side. Finally, the power is transmitted from the gear 41 to the gear 42, the details of which are shown in FIG. The driving force is transmitted from the gear 38 to the gears 39, 43, 4
4, 45, 46, 47, 48, 49 and recording paper transfer unit 79
Transmitted to the side. Finally, the power is transmitted from the gear 49 to the gear 50, the details of which are shown in FIG. 9 described later.

FIG. 8 is a perspective view of the cleaner 13.
The rotating shaft 70 has its ends 70a and 70b rotatably disposed on a main plate of a device (not shown). A gear 71 is integrally fixed to the shaft 70, and the gear 71 is engaged with the gear 41. A one-way clutch is interposed between the gear 42 inserted into the shaft 70 and the shaft 70, and the gear 42 can rotate counterclockwise freely, but the clockwise rotation follows the rotation of the shaft 70. Is permitted, but is restricted so as not to rotate beyond the rotation of the shaft 70.

The gear 42 is provided with a rack 65A which is guided by guide shafts 72, 72 implanted in a base plate of a device (not shown) in the elongated hole 65Aa, and which is arranged to be movable left and right. One end is connected to the drive shaft of the plunger 66A, and the other end is connected to one end of the connecting plate 64. It is rotatably connected to a pin 62a implanted at the lower end of the holding member 62 provided so as to be able to rotate.

On the intermediate transfer sheet 26 side of the holder 62,
A cleaning blade 63 that comes into contact with the sheet 26 and removes residual toner is fixed with an adhesive or the like, and a shaft 73 is attached to the roof 62 a of the holder 62 by a coil spring 68.
The urging force is applied in the counterclockwise direction with respect to. The illustration shows a state in which the rack 65A is drawn all the way to the left by the plunger 66A, and the cleaning blade 63 and the intermediate transfer sheet 26 are kept in a non-contact state.

In this embodiment constructed as described above, when the gear 71 rotates clockwise by the driving force from the drive source 12 (FIG. 1) and the shaft 70 rotates in the same direction, the shaft 7 rotates.
The gear 42 does not rotate due to the one-way clutch between the gear 0 and the gear 42. On the other hand, when an electric signal is input to the plunger 66A and the force of pulling leftward is released, the rack 65A attempts to move rightward due to the urging force of the spring 68, but reaches the gear 71 from the drive source 12. If the gear 42 is sufficiently decelerated in the process, the gear 42 is regulated by the rotation speed of the shaft 70, the gear 42 cannot move beyond it, and the cleaning blade 63 collides with the intermediate transfer sheet 26 at high speed, The impact does not damage both members, thereby lowering durability and generating no noise.

Even when the shaft 70 is rotating clockwise, when an electric signal comes in with the plunger 66A releasing the holding force, the plunger 66A drives the rack 65A by suction. Then, since the gear 42 can be freely rotated in the counterclockwise direction, the holder 62 automatically returns to the initial position.

FIG. 9 is a perspective view of the recording paper transfer section 79.
The rotating shaft 74 has its ends 74a and 74b rotatably provided on a main plate of a device (not shown). A gear 73 is integrally fixed to the shaft 74, and the gear 73 is engaged with the gear 49. A one-way clutch is interposed between the gear 50 inserted into the shaft 74 and the shaft 74, and the clockwise rotation of the gear 50 is free, but the counterclockwise rotation follows the rotation of the shaft 74. Is permitted, but is restricted so that it cannot rotate beyond the rotation of the shaft 74.

The gear 50 is provided with a rack 65B which is guided by a guide shaft 75 implanted in a base plate of a device (not shown) in a long hole 65Ba and is disposed so as to be movable left and right. A second transfer roller holding plate provided with a second transfer roller 19 rotatably provided around a shaft 67a planted on a ground plate of a device (not shown), which is connected to a drive shaft of the plunger 66B. The other end of the holding plate 67 is biased by a coil spring 69 in the clockwise direction in FIG. The illustration shows a state in which the rack 65B is drawn all the way to the left by the plunger 66B, and the second transfer roller 19 and the intermediate transfer sheet 26 are kept in a non-contact state.

In this embodiment constructed as described above, when the gear 73 rotates counterclockwise by the driving force from the driving source 12 (FIG. 1) and the shaft 74 rotates in the same direction, Gear 50 by a one-way clutch between gear 50
Does not rotate. On the other hand, when an electric signal enters the plunger 66B, the force of pulling to the left is released and the spring 69
The rack 65B attempts to move to the right due to the urging force, but the gear 50 is restricted to the rotation speed of the shaft 74 if the speed is sufficiently reduced in the process from the drive source 12 to the gear 73,
The gear 50 cannot move beyond it, and the second transfer roller 19 collides with the intermediate transfer sheet 26 at high speed,
The impact does not damage both members, thereby lowering durability and generating no noise.

Even if the shaft 74 is rotating counterclockwise,
When the plunger 66B releases the holding force and an electric signal comes in, the plunger 66B drives the rack 65B by suction. Since the clockwise rotation of the gear 50 can be freely performed, the second transfer roller holding plate 67 automatically returns to the initial position.

Since the present embodiment is constructed as described above, when the moving member contacts the outer surface of the intermediate transfer member without using a special damper, it does not give an impact to the outer surface.
It is possible to provide an image forming apparatus having improved durability without causing a time loss until the movable member is stably pressed against the intermediate transfer member due to vibration of the damper or the like.

When the moving member is adapted to the cleaning blade, the moving member does not give an impact to the outer surface of the intermediate transfer member even if a special damper is not used. Because time loss does not occur until the stable pressing of the moving member to the intermediate transfer body by the etc.
The cleaner section can be located closer to the recording transfer section on the upstream side, and the apparatus can be made smaller.

Further, when the moving member is adapted to the recording paper transfer roller, the moving member does not give an impact to the outer surface of the intermediate transfer drum even if a special damper is not used. Since no time loss occurs until the movable member is stably pressed against the intermediate transfer drum due to vibrations of the recording paper, an image can be transferred to an accurate position on the recording paper in synchronization with the recording paper having a determined margin.

The moving member is a recording paper transfer roller and a cleaning blade. If the one-way driving member connected to both is driven by the same driving source, the cleaner is located on the upstream side. Even in the case where the distance between the moving member and the recording transfer unit is short, the driving speed of both moving members can be regulated to be constant, and the stable pressing position of both members can be accurately controlled.

Further, when the recording paper transfer roller, the respective one-way drive members connected to the cleaning blade and the intermediate transfer drum are configured to be driven by a reduction gear train connected to the same drive source, the intermediate transfer The moving speed of the drum and the moving speed of the one-way driving member are made to correspond to the number of teeth of the gear, and when the intermediate transfer drum rotates to the number of moving teeth of the intermediate transfer drum, it contacts the outer surface of the intermediate transfer drum. Can be precisely controlled.

Further, if the holding means is a plunger and is configured to control suction, holding and release of the moving member by an electric signal, the moving member needs to drive a driving mechanism or the like to return to the initial position. In addition, since the plunger can be driven and returned by an electric signal, the return is completed quickly without driving an extra mechanism with a simple configuration. Therefore, when a trouble occurs due to a jam of the recording transfer paper, it is not necessary to reversely drive the moving member to return the driving mechanism to the initial position after removing the transfer paper.
Since the drive mechanism is not driven from the drive source unnecessarily, the durability is improved.

The holding means of the present embodiment is constituted by a plunger, and the moving member is sucked, held, and held by an electric signal.
It is configured to control release. Therefore, a capacitor and a pulse generator are prepared as means for generating an electric signal, and the capacitor is charged while the power is being supplied to the device, and the electric charge charged in the capacitor is discharged after a predetermined time in synchronization with the power interruption. Then, by applying the electric signal to the plunger in a pulse shape, the plunger can be driven to return the moving member to the initial position.

Further, the moving member is self-held in the initial position by the permanent magnet in the plunger, and by supplying power, the moving member is driven against the self-holding force, and the moving member is shut off by power supply. You may comprise so that it may return to an initial position by the attraction force of the said permanent magnet.

With this configuration, the holding means can suck and hold the moving member in synchronization with the power cutoff, and when the power is cut off due to a recording paper jam, power failure, or the like, the moving member is automatically turned on. To return to the initial position
Since the intermediate transfer sheet and the moving member do not come into contact with each other under the condition that the power is shut off, the moving member is held in a non-contact state with the intermediate transfer sheet in a non-use state. And does not adversely affect image formation.

Next, an auxiliary roller mechanism for efficiently rotating the intermediate transfer sheet 26 of the intermediate transfer drum 11 will be described. 2, the intermediate transfer drum 11 has a flange 29
Is rotated by the driving force of the gear 29a, and the portion of the intermediate transfer sheet 26 is provided in the intermediate transfer drum 11 and is driven by various rollers and the photosensitive drums 9A and 9B. In the photosensitive drums 9A and 9B and the first transfer rollers 59A and 59B provided opposite thereto, the portion sandwiched between the photosensitive drum and the transfer roller is efficiently rotated, but the other backup rollers 58 Only the portion of the intermediate transfer sheet 2
6, a partial delay occurs, and the sheet is distorted, which affects image formation.

In this embodiment, the auxiliary roller 60 is rotatably disposed on the auxiliary roller retainer 61 having a spring property (FIGS. 8 and 9), and the backup rollers 58A, 58B, 58
C, 58D, an appropriate pressing force is applied to the positions at both ends in the longitudinal direction to hold the auxiliary rollers 61A, 61B, 61C, 61.
D is arranged as shown in FIG.

As shown in FIG. 7, these auxiliary roller retainers 61 are fixed to a base plate portion of a device (not shown).
As shown in FIG. 9, the backup roller 58 is pressed through both ends of the intermediate transfer sheet 26 in the longitudinal direction.

Next, the cleaning blade 63 of the cleaner section 13 and the intermediate transfer sheet 26 used in this embodiment are used.
The contact position will be described. In FIG. 10, the contact end 63a of the cleaning blade 63 is
The backup roller 58D is in contact with the intermediate transfer sheet 26 at a position 82A on the upstream side by a dimension R from a position 81 in contact with the intermediate transfer sheet 26 of the backup roller 58D located on a center line 80 radially emitted from the rotation center of the roller.

Now, as shown in FIG. 11A, the position 81 of the backup roller 58D which comes into contact with the intermediate transfer sheet 26.
When the end 63a of the cleaning blade 63 comes into contact with the intermediate transfer sheet 26 on the further downstream side, a counterclockwise rotational force is applied to the auxiliary tool 62, and the backup roller 58D rotates in the direction of the arrow. Therefore, the intermediate transfer sheet 26 having the locus of 26A at the beginning becomes the locus of 26B due to the frictional force at the contact position 82B, and the angle θ
1 to θ2, which results in damage to the intermediate transfer sheet 26 and the cleaning blade 63.

On the other hand, as shown in FIG.
When the contact position 82A is located further upstream, the counterclockwise urging force of the holder 62 is absorbed by the rotation center 58Da of the backup roller 58D, and the path 26 of the intermediate transfer sheet 26
A does not change and the angle θ3 does not change, and the intermediate transfer sheet can be driven stably.

[0083]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG.
Comes into contact with each roller at an angle α and leaves at an angle β. These angles are determined by the backup auxiliary roller 57.
For A, α57A is 62 °, β57A is 115 °
It is. Hereinafter, when these data for each roller are described, the first transfer roller 59A has α59A of 65 °,
β59A is 115 ° and backup roller 58A is α
58A is 70 °, β58A is 115 °, and the backup roller 58C is α58C at 70 ° and β58C is 111.
°, backup roller 58D, α58D is 66 °,
β58D was 112 °.

Note that the backup auxiliary roller 57B
7A has the same data as 57A because it is a radial shaft extending outward from the rotation center 11a of the intermediate transfer drum 11 and uses the same members. Also, the first transfer roller 59B has the same data as 59A, and the backup roller 58B has the same data as 58A. As is apparent from these data, the contact and separation between the roller and the cam 35 are performed between 62 ° and 115 °.

[0085]

As described in detail above, the present invention has a simple structure, and allows the intermediate transfer drum by the moving member to be precisely timed.
It is possible to provide an image forming apparatus capable of forming a stable image by being capable of being locally pressurized and retracted, and by reducing vibration and impact.

[Brief description of the drawings]

FIG. 1 is an external view of an image forming apparatus to which the present invention is applied.

FIG. 2 is a schematic diagram illustrating an intermediate transfer drum and a mechanism around the intermediate transfer drum.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a view as seen from the BB direction in FIG. 3;

FIG. 5 is a configuration diagram of a roller disposed in the intermediate transfer drum.

FIG. 6 is an operation diagram of a roller disposed in the intermediate transfer drum.

FIG. 7 is a mechanism diagram of a cleaner unit and a recording paper transfer unit.

FIG. 8 is a perspective view of a cleaner unit.

FIG. 9 is a perspective view of a recording paper transfer unit.

FIG. 10 is a partially enlarged view of a cleaner portion.

FIG. 11 is an explanatory diagram of an operation of a cleaner unit.

[Explanation of symbols]

 Reference Signs List 9 photosensitive drum 10 developing device 11 intermediate transfer drum 12 drive source 13 cleaner unit 14 paper cassette 15, 25 roller 18 registration roller 19 second transfer roller 20 transport device 22 fixing unit 26 intermediate transfer sheet 27 intermediate transfer drum shaft 28 shaft head 29 Flange 35 Cam 36 Support 37 Press plate 52 Shaft support 53, 70, 74 Shaft 55 Damper 56 Biaxial bearing 57 Backup auxiliary roller 58 Backup roller 59 First transfer roller 60 Auxiliary roller 61 Auxiliary roller presser 62 Holder 63 Cleaning blade Reference numeral 64 Communication plate 65 Rack 66 Plunger 67 Second transfer roller holding plate 79 Recording paper transfer unit

Claims (7)

(57) [Claims] 1. An image forming apparatus having an intermediate transfer drum and a moving member that comes into contact with and separates from the outer surface of the drum, the image forming apparatus having a biasing force toward the outer surface of the intermediate transfer drum, and A moving member for contacting and pressing the outer surface thereof, holding means for holding the moving member away from the outer surface against the urging force, and releasing the moving member to allow the moving member to travel, A one-way rotation drive member connected to the movement member and receiving rotation drive force from the rotation drive source in only one direction; and a one-way rotation drive member provided on the one-way rotation drive member; Follow and move,
The one-way rotation drive member includes a one-way clutch configured to be freely movable in a counter rotation direction of the one-way rotation drive member, and the movement member is rotated by the one-way rotation drive member by releasing the holding member. An image forming apparatus provided with a moving member whose moving speed is controlled, wherein the moving member is controlled in speed so as to approach the outer surface. 2. The image forming apparatus according to claim 1, wherein the moving member is a cleaning blade. 3. The image forming apparatus according to claim 1, wherein the moving member is a recording paper transfer roller. 4. The moving device according to claim 1, wherein the moving member is a recording paper transfer roller and a cleaning blade, and the one-way rotation driving member connected to the both is driven by the same driving source. An image forming apparatus including a moving member whose speed is controlled. 5. The recording paper transfer roller, the one-way rotation driving member connected to a cleaning blade, and the intermediate transfer drum are driven by a reduction gear train connected to the same driving source. Item 5. An image forming apparatus comprising the moving member whose moving speed is controlled according to Item 4. 6. The image forming apparatus according to claim 1, wherein said holding means is a plunger and controls suction, holding and release of said moving member by an electric signal. . 7. The image forming apparatus according to claim 6, wherein the holding unit sucks and holds the moving member in synchronization with power cutoff.