JPH1039662A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the image accuracy by installing two-series communicating means of an image holding member and an intermediate transfer member from a motor, for reducing the engaging parts and reducing the driven inversion of the back lash by the variation of load to the intermediate transfer member. SOLUTION: An image holding member 1 and an intermediate transfer member 2 are driven by a motor 3. A driving gear 4 of the image holding member 1 is engaged with a gear part 3a of the motor 3. The other gear part 3b is installed at the opposite side of the gear part 3a, and these gear parts 3a, 3b are fixed in the rotating direction, so that the relative position of these is not changed. Further an idler 10 is held by a holding box 11 of the intermediate transfer member 2, and a gear 10a is fixed on the same axis. By using one motor 3 as a driving source, an image accuracy is not affected by the variation of load of the transfer roller or the like. Further by installing the idler gear 10, the variation of the contact pressure to the image holding member 1 can be prevented, even when the external load is varied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic or electrostatic recording type color image forming apparatus such as a color copying machine or a color printer.

[0002]

2. Description of the Related Art FIG. 5 is a sectional view of a conventional color laser printer. First, a conventional color laser printer will be schematically described with reference to FIG. The primary charger is a charging roller 104b to which a voltage is applied, which is pressed against the image carrier 104a, and uniformly charges the surface of the image carrier 104a by the charging roller 104b prior to forming a latent image.

[0005] Exposure to the image carrier 104a is performed by a scanner unit 110a having a laser diode.
The laser diode emits light in response to the image signal and irradiates a polygon mirror (not shown). The polygon mirror is rotated at high speed by a scanner motor (not shown) and reflects a laser beam. The laser beam reflected by the polygon mirror selectively exposes the outer peripheral surface of the image carrier 104a via the coupling lens 110b and the reflection mirror 110c in accordance with the image signal. The image carrier 104a forms an electrostatic latent image of each color by laser exposure.

The rotary developing device 105 includes a plurality of color developing devices,
That is, the developing devices 105M, 105C, 105Y, and 105K provided with magenta, cyan, yellow, and black toners.
have. These four color developing units are a rotary developing device 1
The center of each developing unit is rotated in conjunction with a rotating gear disposed on the outer periphery of the revolving gear, and its posture is maintained constant. At the time of image formation, a developing device 105 of a color corresponding to the latent image is stopped at a position facing the image carrier 104a, and further, there is a developing sleeve 1 as a developer (toner) carrier.
05b is positioned so as to face the surface of the image carrier 104a via a minute gap.

When the developing device is rotated to the developing position, the developing sleeve 1 is connected to the high voltage power source of the printer main body.
05b performs a predetermined rotation while being coupled with the driving means from the driving source at the same time when the developing bias is applied. At the time of development, the latent image on the image carrier 104a is developed by receiving the bias application and the rotation drive of the developing sleeve 105b to form a toner image.

A paper feeding unit 101 is for feeding the transfer material 102 to the transfer drum 103, and is provided with a paper feed cassette 101a for storing the transfer material 102 loaded at the bottom of the apparatus main body.
have. At the time of image formation, the paper feed roller 101b rotates according to the image forming operation, and separates the transfer materials 102 one by one from the paper feed cassette 101a and feeds them to the transfer drum 103.

The transfer drum 103 wraps the transfer material 102 fed from the paper supply unit 101 and transfers the toner images of each color on the image carrier 104a onto the transfer material 102 at the transfer unit. At the same speed (for example, V = 75.4 mm / sec) (hereinafter referred to as process speed).

The transfer drum 103 has an elastic layer 103b formed of sponge, rubber or the like on the outer periphery of an aluminum cylinder 103a having a diameter of 180 mm, a resistive layer 103c formed on the outer periphery thereof, and a dielectric layer 103d formed on the outermost layer. It is constituted by doing. At a predetermined position on the outer periphery of the transfer drum 103, a gripper 103f for gripping the leading end of the fed transfer material is provided. Further, an electrostatic attraction roller 103g is provided on the outer periphery of the transfer drum 103 so as to be able to be separated from and brought into contact with the outer periphery of the transfer drum 103 so as to sandwich the transfer material 102 between the transfer drum 103 and the attraction roller 103g. Then, the suction roller 103g and the transfer drum 103
, A charge is induced in the dielectric transfer material 102 and the dielectric layer 103 d of the transfer drum 103, and the transfer material 102 is electrostatically attracted to the outer periphery of the transfer drum 103.

The cleaner 104d is for cleaning the toner remaining on the image carrier 104a after being transferred to the transfer material 102.
4a.

The fixing unit 106 is driven by the pressure roller 10.
6a, and a fixing roller 106b which presses against this and applies heat and pressure to the transfer material. Transfer material 1 that holds toner images of each color and is peeled and conveyed from transfer drum 103
02 through the transfer material 1
02 is fixed.

The image forming operation includes a sheet feeding cassette 101
The transfer material 102 in a is fed to the transfer drum 103 by the paper feed roller 101b. The transfer drum 103 grips the leading end of the fed transfer material 102 with a gripper 103f and electrostatically attracts the peripheral surface thereof.

On the other hand, the image carrier 104a whose surface is uniformly charged by the primary charger 104b is exposed to a magenta image from the scanner unit 110a, and forms a latent image of the magenta image on the outer peripheral surface thereof. At the same time as the formation of the latent image, the magenta developing unit 105M is driven to charge the image carrier 104a with the same polarity and substantially the same developing bias so that the magenta toner adheres to the magenta latent image formed on the image carrier 104a. A voltage is applied to develop, and a magenta toner image is obtained on the image carrier 104a. Then, a transfer voltage having a polarity opposite to that of the magenta toner is applied to the transfer drum 103 to transfer the magenta toner image on the image carrier to the transfer material 102 on the transfer drum 103.

When the transfer of the magenta toner image is completed, the next cyan developing unit 105C rotates and is positioned at the developing position opposed to the image carrier 104a.
The formation of latent images of cyan, yellow, and black, development, and transfer of the obtained toner image are sequentially performed, and a full-color image is formed on the transfer material 102.

By rotating the transfer drum holding the transfer material 102 by four rotations, one four-color full-color image can be obtained. That is, 180π × 4 /
One full color is output in 75.4 = 30 seconds.

The transfer material on which the transfer of the four-color toner image has been completed is
After being separated from the transfer drum 103 and conveyed to the fixing unit 106, where the fixing unit 106 fixes the toner image, the toner image is discharged to the discharge tray 108 by the discharge roller pair 107.

[0016]

However, in the above-mentioned prior art, the driving gear of the image carrier, the two rows of idler gears,
It is necessary to provide an intermediate transfer member (transfer drum) and a transmission path, and the intermediate transfer member has four gear engagement portions,
There are many causes of pitch unevenness, and reversal of sub-drive is likely to occur for a long time due to excessive backlash in response to load fluctuation on the intermediate transfer member, for example, contact of the transfer roller. This is more conspicuous as the number of gear meshing points increases, and adversely affects image accuracy.

Next, the gear immediately before the intermediate transfer member has a swing mechanism (not shown). This is to bring the intermediate transfer member into contact with the image carrier and to absorb variations in the outer diameter of both drums (the intermediate transfer member and the image carrier). When the transfer roller is brought into contact, for example, the idler gear oscillates to generate a component force, the contact pressure contact between the image carrier and the intermediate transfer member fluctuates, and image density unevenness occurs.

Next, it is desirable that the driving gear of the image carrier has a larger pitch circle than that of the image carrier in order to reduce pitch unevenness due to engagement of one pitch on the image carrier. Since the layout has to be very close, the layout protrudes outside the main body housing. As a result, the drive gear of the intermediate transfer member and the drive gear of the image carrier driven by the motor gear must be largely separated. Therefore, in the case of a conventional one-axis motor, it is necessary to provide an idler gear having an axial length between the motor gear and the driving gear of the intermediate transfer member. It is necessary to provide a pair of bearings for an idler gear having gears at both ends. Further, in order to accurately maintain the center distance between the gears, it is necessary to provide a highly rigid fixture.

Next, in a configuration in which two series of drive transmission means of an intermediate transfer body and an image carrier are provided, when the image carrier and the intermediate transfer body are inserted and then the intermediate transfer body is brought into pressure contact, Normal,
The driving frame does not fit into the concave portion provided in the image carrier. In such a state, when driving by the motor is started, the image carrier starts image formation by the driven rotation by the rotation of the intermediate transfer member. However, the image carrier rotates at a slightly different rotation speed from the ideal rotation speed due to variations in the outer diameter of the intermediate transfer member and the image carrier, and variations in the contact pressing force. When the relative angular position of the concave portion of the carrier is matched), the driving piece fits into the concave portion of the image carrier. At this moment, a sudden load fluctuation occurs, and during image formation, image disturbance occurs.

Further, in order to prevent the motor from following the shocking load fluctuation, and to prevent the stepping motor from losing synchronism and not returning to the original state,
Unnecessary high current required high torque driving or the use of large capacity motors.

In the case of an image forming apparatus aiming at high image accuracy, positioning of an image carrier, a motor, a gear and an intermediate transfer member is important. In this conventional example, a driving device including a motor, a driving gear of an image carrier, and a shaft is provided outside a main body housing. This is because the ease of assembling to the main body housing and the ease of maintenance are taken into account. The intermediate transfer body unit including the intermediate transfer body and the driving gear of the intermediate transfer body is inside the main body housing. In order to perform high-precision positioning of the drive component including the swing pressure mechanism, it is necessary to use a simple penetrating member as much as possible.

Next, in the preparation stage of the image forming operation, the rotation speed of the intermediate transfer member is intentionally changed by changing the pressing force or the amount of the intermediate transfer member applied to the image carrier, thereby completing the coupling. It is also effective, but it takes time to connect the coupling or secure a sufficient amount of penetration, and increase the speed difference between the rotation speed from the image carrier and the rotation speed from the intermediate transfer body. Care must be taken. In order to secure a sufficient amount of penetration, the surface layer of the intermediate transfer member must be thickened, and the increase in the amount of the elastic body increases the cost.

The connection operation of the coupling needs to be performed when the image carrier is detached. When the coupling play of the coupling is as small as about 10 mm and the intermediate transfer body is driven by a motor, the gear train of the intermediate transfer body, the motor, Even if the coupling is rotated, the intermediate transfer member may be brought into contact with the coupling member without being able to be coupled without intentionally rotating the coupling on the image carrier unit side.

Accordingly, it is an object of the present invention to provide an image forming apparatus which has solved the above-mentioned disadvantages of the prior art.

[0025]

SUMMARY OF THE INVENTION The above-mentioned object of the present invention is as follows.
This is achieved by an image forming apparatus configured according to the present invention described below. That is, in the present invention, first, by providing two series of transmission means of the image carrier and the intermediate transfer member from the motor, the number of meshing portions is reduced, and the follow-up inversion of the backlash due to the load fluctuation on the intermediate transfer member is reduced. I do. Thereby, image accuracy is improved.

In the present invention, secondly, an idler gear is provided at the center of the pressure swing of the intermediate transfer member in contact with the image carrier. Thus, a stable contact pressure is maintained irrespective of the load change and the difference in the outer diameter of the image carrier and the intermediate transfer body, and the image density unevenness is prevented.

Third, the present invention provides a motor between the drive gear of the intermediate transfer member and the drive gear of the image carrier, and a shaft provided in both directions from the motor, and a gear provided at each end of the shaft. This eliminates the need for an idler gear with a long shaft,
By using a pair of bearings in the motor, a highly rigid fixture is not required, and the distance between the gear centers can be accurately maintained.

Fourth, the present invention drives the two-line drive transmission means to the intermediate transfer member and the image carrier before the intermediate transfer member contacts, thereby preventing image disturbance during image formation and eliminating the need for a motor. Or to use a motor of an appropriate capacity.

Fifth, the present invention makes it possible to obtain the same effects as described above by setting the rotation at a speed lower than the rotation at the time of image formation in the preparatory stage (ie, at the time of coupling).

Sixth, in the present invention, the amount of pressurization (or the amount of intrusion) is switched between the preparatory stage and the time of image formation, so that the connection of the coupling to the image carrier in the preparatory stage is quickly and reliably performed.

Seventh, the present invention uses a positioning protrusion of a motor, penetrates a positioning hole of a driving device to a main body housing, and further, a mounting positioning hole of a holding guide plate of a driving idler gear of an intermediate transfer body. , The gear distance between the motor and the intermediate transfer member is accurately maintained.

Eighth, in the present invention, since the image carrier is driven by the intermediate transfer member in the coupling operation, the relative rotational speed difference between the image carrier and its driving gear is only a very small amount. Consider spending time up to
The drive of the intermediate transfer member is actively stopped to speed up the completion of the coupling. In addition, when the intermediate transfer member is attached or detached, the drive transmission is released to improve the operability deterioration due to the engagement of the gear.

According to the ninth aspect of the present invention, the image bearing member and the intermediate transfer member are rotated in a preparation stage accompanying a power reset.
By performing at least one operation of releasing and returning the drive transmission during this time, image disturbance due to sudden connection of the coupling during image formation is prevented. At the same time, the motor drive current is set high only during the preparation stage, thereby preventing the motor from stepping out and cutting unnecessary current. As a result, heat resistance is also advantageous. For example, an electromagnetic clutch is used for releasing and returning the drive transmission. Since this electromagnetic clutch is used so that transmission is performed most of the time, it is better to use a type that transmits when the current is turned off.

[0034]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a view for explaining a driving device used in the image forming apparatus of the present invention. FIG. 1a is a front view of the driving device, and FIG. FIG. In FIG. 1, the image carrier 1 (corresponding to the image carrier 104 in FIG. 5) and the intermediate transfer member 2 (corresponding to the transfer drum 103 in FIG. 5) are driven by a motor 3 as described later in detail. You.

The drive gear 4 of the image carrier 1 is engaged with the gear 3a of the motor 3, and the drive shaft 5 of the image carrier 1 is fixed so as to pass through the drive gear 4. As shown in FIG. 1B, a drive shaft 5 of the image carrier 1 is slidably fitted with a coupling 1a on a side portion of the image carrier 1 and has a pin 6 for transmitting a driving force in a rotational direction. Is caulking. Specifically, the pin 6 is slidable along an axial long groove 5 ′ formed on the drive shaft 5. When the coupling 1a is inserted into the drive shaft 5 at a position different from the fitting position on the back surface of the top 7 (when the angular positions of the top 7 and the coupling 1 do not match), the top 7 is retracted. When rotated to the fitting position (when the angular positions match), a spring 9 for coupling the top 7 and the coupling 1a is used.
Is provided. That is, the spring 9 couples the top 7 to the coupling 1
a. Specifically, the coupling 1a
Has a notch 1a 'having a U-shaped cross section, and the top 7 has a protruding member 8 for engaging with the notch 1a'. The protruding member 8 has a cross section as shown in FIG. 1
a has a width (perpendicular to the drawing) larger than the width of the cut 1a '. Therefore, the coupling 1a
Each time it rotates by 180 °, it is fitted with the top 7. FIG. 1A shows a state in which the coupling 1a and the top 7 are fitted.

The motor 3 has another gear portion 3b on the side opposite to the gear portion 3a, and these gear portions 3a, 3b are fixed in the rotation direction, and their relative positions do not change. Although the same member is used here, a pinion may be used, and the gear portions 3a and 3b need not be gears of the same specification. The idler gear 10 is an intermediate transfer member 2
And the gear 10a is coaxially held
Has been fixed. The gear 10a is engaged with the drive gear 12 of the intermediate transfer body 2, and drives the intermediate transfer body 2 to rotate. The ring-shaped convex portion 11a serving as a rotation center when the intermediate transfer body 2 swings and abuts on the image carrier 1 is located at a position concentric with the idler gear 10, and is positioned through by the positioning convex portion 3c of the motor 3. It is held by the holding and fixing plate 13 to keep the accuracy of the center-to-center distance between the gear portion 3b and the idler gear 10 good.

The motor 3 has bearings (not shown) such as bearings at both ends inside. The motor 3 is arranged between the drive gear 4 of the image carrier 1 and the drive gear 12 of the intermediate transfer body 2 to achieve high height. A rigid drive is obtained.

When the image carrier 1 is set by moving the image carrier 1 in the direction indicated by the arrow A in the preparation stage before the image forming operation, the relative angular positions of the coupling 1a and the frame 7 are shifted. The coupling 1a and the top 7 do not fit,
Top 7 retreats. When the intermediate transfer body 2 is brought into a swinging contact in this state, the coupling 1a is fitted to the frame 7 even during image formation due to a slight rotation variation, and as a result, the image is disturbed due to a sudden change in torque, and the motor loses synchronism. Will be.

Therefore, it is preferable to fit the coupling 1a and the frame 7 in a preparatory stage before the image forming operation, and the procedure will be described with reference to FIG. FIG. 2 is a plan view of the driving device of the present invention. The cam 15 is fixed to the stepping clutch 14 and is configured to rotate with the rotation of the stepping clutch. In a preparation stage before the image forming operation, the cam 15 is retracted to the initial position by the 180 ° stepping clutch 14. On the other hand, in this embodiment, the coupling 1a is formed so as to be fitted to the top 7 every 180 degrees of the rotation angle (formed so that the relative angular positions coincide). Therefore, the motor 3 is driven so that the driving gear 4 of the image carrier 1 rotates 180 ° or more. The intermediate transfer member 2 is driven to rotate, but when the coupling is performed, the cam 15 is retracted to the initial position, so that the intermediate transfer member 2 is not in contact with the image carrier 1 and the image carrier 1 is stopped. is there. After rotation of the motor for a predetermined time (because the coupling 7a and the coupling 7 are fitted after rotating the coupling 7 by an angle of 180 ° or more), the stepping clutch 14 is turned on, and the cam is rotated to the contact position. The cam 15 acts to press the outer peripheral surface of the intermediate transfer body 2, and the reaction force causes the housing 11 to rotate around the idler gear 11 to bring the intermediate transfer body 2 into contact with the image carrier, thereby preparing To end. The reference numeral 22 denotes a gear, and the gear 22 rotates constantly so as to transmit a torque from a motor (not shown) to the stepping clutch 14.

In the coupling operation in the preparation stage, the frame 7 is rapidly coupled to the coupling 1a even though the image carrier 1 is stopped, so that the step-out occurs when the motor 3 is a stepping motor. , There is a risk of stopping.
To avoid this, it is preferable to perform the coupling operation by rotating the motor 3 at a lower speed than the rotation during image formation.

Next, an example in which the present invention is provided with a mechanism for adjusting the contact pressure of the intermediate transfer member will be described with reference to FIG. FIG.
It is sectional drawing of the adjustment mechanism of the contact pressure used by a drive device. In FIG. 3, the adjusting mechanism is attached to the housing 11 at the same position as in FIG. 2, and the spring end plate 16 has a knurled outer periphery and a threaded inner periphery. . A pressing member 18 such as a spring is disposed between the spring end plate 16 and the cap member 17, whereby the cap member 1 is moved.
7 is preloaded outward. After setting the intermediate transfer body unit on the main body, the cap member is pressed by a lever 19 attached to the main body side and manually moved, and the holding housing 11, and therefore, the intermediate transfer body 2 is rotated about the idler gear 10, and the intermediate transfer body is rotated. The transfer member 2 is pressed against the image carrier 1. Thereafter, when the coupling is executed, the spring end plate 16 is manually rotated to move to the coupling rotation position B. As a result, the pressing force changes, the amount of the intermediate transfer body 2 abutting on the image carrier 1 changes, and the driven image carrier 1 rotates slower than the rotation during image formation. That is, a speed difference occurs between the image carrier 1 and the drive gear 4. After rotating for an appropriate time, the coupling is completed. At the time of image formation, the spring end plate 16 is rotated again to return to the image forming position A.

Next, another embodiment of the coupling will be described with reference to FIG. FIG. 4 is a front view showing another embodiment. In FIG. 4, the electromagnetic clutch 21 is provided between the idler gear 10 and the gear 10a, and is held by the intermediate transfer unit 20. For example, electromagnetic clutch 2
In the ON state, the gear 10a is separated from the idler gear 10, and in the ON state, the gear 10a is
Combined with 0. Therefore, the electromagnetic clutch
F to the gear 3a from the idler gear 10
When the rotational force from the image carrier is not transmitted, the image carrier 1
When the intermediate transfer member 2 and the intermediate transfer member 2 are engaged with each other, the intermediate transfer member 2 is stopped, and the image carrier 1 is also stopped. As described above, when the rotation of the image carrier 1 is positively stopped from the idler gear 10 and the motor 3 is driven, the coupling is completed.

For example, when a jam occurs, the electromagnetic clutch 21 is turned on and off at least once in the preparation stage, and the image carrier 1 is detached. Alternatively, when a new image carrier is used, the case where the coupling is not connected is prepared.

[0045]

【The invention's effect】

(1) By driving the intermediate transfer member and the image bearing member by two drive transmission means using one motor as a drive source, the influence of image accuracy on load fluctuations such as the transfer roller is small. (2) Since the idler gear of the drive transmission means is provided at the swing center of the contact of the intermediate transfer member with the image carrier, the image carrier can be used even when the external load fluctuates when the transfer roller contacts the intermediate transfer member. The change of the contact pressure against the contact can be suppressed. (3) Since the image carrier, the intermediate transfer member, and the drive motor are provided between the two drive gears, there is no need to provide an axial idler gear, and the motor bearing is used, so that the rigidity is high.
The distance between the gear centers can be accurately maintained. (4) The motor is driven before the swinging of the intermediate transfer member and swings after the coupling, so that the drive is reliably transmitted, so that unnecessary high current does not flow and a large-capacity motor is used. No need to use. (5) In the preparatory stage before the image forming operation, the motor is rotated at a lower speed than during the image forming, so that the motor out-of-step which occurs at the time of a sudden coupling coupling can be reduced. (6) Also, in the preparatory stage before the image forming operation, it is possible to set a pressure amount or an approach amount different from that at the time of image forming, thereby realizing an early coupling operation. (7) The positioning of the drive device to the main body housing and the mounting and fixing of the holding / fixing guide plate of the idler gear for driving the intermediate transfer body are performed by the positioning projections of the intermediate transfer body and the image carrier drive motor, so that the drive transmission means High-precision positioning is achieved, and pitch unevenness can be reduced. (8) By providing an electromagnetic clutch between the motor and the intermediate transfer member, only the drive gear of the image carrier can be positively rotated,
The coupling operation can be terminated early. Further, when the drive transmission is turned off at the time of attaching and detaching the intermediate transfer member, the operability of the intermediate transfer member can be improved. (9) Similarly, when the drive transmission is turned off and on by the electromagnetic clutch at least once in the preparation stage before the image forming operation, unnecessary current can be cut off, and the heat resistance is also advantageous.

[Brief description of the drawings]

FIG. 1 is a side view for explaining a driving device used in an image forming apparatus of the present invention.

FIG. 2 is a plan view of the driving device of the present invention.

FIG. 3 is a sectional view of a contact pressure adjusting mechanism used in the driving device.

FIG. 4 is a side view of a drive device according to another embodiment using an electromagnetic clutch.

FIG. 5 is a side view showing the overall configuration of a conventional example and the image forming apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image carrier 2 Intermediate transfer body 3 Motor 3a, 3b Gear part 3c Positioning convex part 4 Image carrier drive gear 5 Image carrier drive shaft 6 Pin 7 Frame 8 Frame fitting part 9 Spring 10 Idler gear 11 Intermediate transfer body holding case Body 11a Swing center 12 Intermediate transfer body drive gear 13 Drive shaft 14 180 ° stepping clutch 15 Cam 16 Spring end plate 17 Cap member 18 Pressurizing member 19 Lever 20 Intermediate transfer body unit 21 Electromagnetic clutch

Claims (12)

[Claims] An image carrier having an intermediate transfer body, an image carrier, and a common motor for driving the intermediate transfer body and the image carrier, wherein a transfer material gripped by the intermediate transfer body carries a toner image. In an image forming apparatus including a step of transferring a toner image to a transfer material by abutting on a body, a first driving force transmitting means for transmitting a driving force from a motor to an intermediate transfer member, and the first driving force transmitting means are separate from each other. And a second driving force transmitting means for transmitting driving force from the motor to the image carrier, provided in the image forming apparatus. 2. The image forming apparatus according to claim 1, wherein
Swinging contact means for swinging the intermediate transfer body to abut against the image carrier, wherein the first driving force transmitting means comprises a gear train, and the gear train is fixed to a motor shaft. And an idler gear engaged with the gear, wherein the swing center of the swing contact means coincides with the center of the idler gear. 3. The image forming apparatus according to claim 1, wherein
The image forming apparatus according to claim 1, wherein the second driving force transmitting unit includes a coupling unit between the motor and the image carrier. 4. The image forming apparatus according to claim 1, wherein
The motor has a shaft extending in both directions, and first and second gears are provided at both ends of the shaft. One of the first gears is a gear of the first driving force transmitting means, and the other is a gear of the first driving force transmitting means. Wherein the second gear is a gear of the second driving force transmitting means. 5. The image forming apparatus according to claim 4, wherein
The second driving force transmitting means includes a third gear engaged with the other second gear of the motor, a hollow shaft supporting the third gear, and a rotational movement restricted inside the hollow shaft. A frame means slidably disposed and slidable between a coupling position and a non-coupling position, and couplable at the coupling position with respect to the frame means and supported by the image carrier. An image forming apparatus comprising: 6. The image forming apparatus according to claim 5, wherein
The image forming apparatus is characterized in that the coupling between the frame unit and the coupling unit is performed by rotating the frame unit by driving the motor while the image carrier is stopped. 7. The image forming apparatus according to claim 6, wherein
The image forming apparatus according to claim 1, wherein the coupling is performed at a lower speed than a rotation of a motor during normal image formation. 8. The image forming apparatus according to claim 7, wherein
The image forming apparatus further includes a swing contact unit that swings the intermediate transfer body to make contact with the image carrier, wherein the swing contact unit includes:
An image forming apparatus comprising: a switching unit that switches a swing contact force according to the coupling or the image formation. 9. The image forming apparatus according to claim 8, wherein
The switching means is a screw means fixed to the intermediate transfer member, a spring end plate screwed to the screw means, and is arranged to be opposed to the spring end plate and to be able to be pressed from outside toward the spring end plate. An image forming apparatus comprising: a cap member provided; and a spring disposed between the spring end plate and the cap member. 10. The image forming apparatus according to claim 1, wherein the motor has a positioning projection, and the projection is used for both positioning with respect to the main body housing and positioning with respect to the intermediate transfer body. Image forming device. 11. The image forming apparatus according to claim 1, further comprising an electromagnetic clutch provided between said motor and said intermediate transfer member, wherein said electromagnetic clutch is turned on and off.
An image forming apparatus according to claim 1, wherein the driving force from the motor is transmitted to the intermediate transfer member, or the driving force is not transmitted from the motor to the intermediate transfer member. 12. The image forming apparatus according to claim 11, wherein the second driving force transmitting unit has a coupling unit between the motor and the image carrier, and connects the image carrier and the intermediate transfer member. In the contact state, the driving force from the motor is not transmitted to the image carrier by the electromagnetic clutch,
An image forming apparatus, wherein coupling is performed by the coupling unit.