JPH0943928A - Image forming device - Google Patents

Abstract

(57) Abstract: To suppress image jitter due to mechanical vibration. In a first aspect, a driven side gear (303) for rotationally driving a contact charging means (201), a gear for rotating and driving the gear by directly or indirectly meshing with the gear (303) Drive side gear
(302), and an electric motor (300) for rotating the driving side gear (302), which is separate from the main motor (400) and is exclusively used for rotationally driving the contact charging means (FIG. 1). . In the second mode, an electric motor for driving the sheet feeding means and the conveying means, which rotationally drives the image bearing member (11) and the contact charging means (201).
An electric motor (43) dedicated to rotationally driving the image bearing member and the contact charging means was provided separately from the motor (FIG. 2). In the third aspect,
Driving force transmission system (402, 40) that rotationally drives the contact charging means (201)
The clutch drive system (35-37), which is a separate system from the
(Figure 4).

Description

Detailed Description of the Invention

[0001]

The present invention relates to charging a photoreceptor,
The present invention relates to an image forming apparatus in which a charged surface is exposed with image light to form an electrostatic latent image and the electrostatic latent image is visualized by a developing device. In particular, a photoreceptor is contact-charged with a charging roller or a charging belt. Alternatively, the present invention relates to a contact charging type image forming apparatus in which a visible image of a photoconductor is contact-charged by a transfer roller or a transfer belt. This type of image forming apparatus is used in a copying machine, a printer, a facsimile machine and the like.

[0002]

2. Description of the Related Art In a contact charging type image forming apparatus,
The contact charging member (charging roller, charging belt) that uniformly charges the photoconductor and the contact transfer member (transfer roller, transfer belt) that transfers the visible image onto the transfer paper transfer the toner image (visual image). A visible image carrier to be formed (generally a photoconductor, but
In the case of recording, an intermediate transfer medium such as an intermediate transfer drum or an intermediate transfer belt for color superposition is also included) at all times or during contact with an image. These contact charging and transfer members are made of an elastic material in order to avoid scratches and vibrations on the image bearing member as much as possible when contacting the image bearing member. To drive the contact charging / transfer member, a driving force is transmitted from a main motor of the image forming apparatus through a gear.

FIG. 6 shows one of copying machines of this type. This is a two-color simultaneous copying machine, which is provided with two charging units each including a charging charger, two exposing units including a writing unit, and two developing units. During image formation (during copying), the photoconductor drum (visual image carrier) 11 is rotationally driven by the main motor, and first, light is emitted by the static elimination means 12 including a static elimination lamp and a static elimination charger to eliminate static electricity. As a result, the surface potential becomes a reference potential of 0V to -100V. Next, the photosensitive drum 11 is uniformly charged by being charged with electric charges by the first charging means 13 composed of a charging charger, and the surface potential becomes about -850V. Digitally recorded image information (black image information) of the original sent from a device (not shown) is received by the line driver circuit of the exposure unit 14 including the first writing unit and amplified by the laser driver circuit. The digital recorded image information is a multi-valued signal of 8 bits per pixel, and the laser driver circuit activates the laser diode in response to the digital recorded image information from the line driver circuit.

Laser light emitted from this laser diode is deflected by an optical deflector composed of a polygon mirror, passes through an f-θ lens, is reflected by a first mirror, a second mirror and a third mirror 141 and is exposed. The image formation and irradiation of the body drum 11 exposes the black original image component. Here, the photosensitive drum 11 includes the third mirror 141.
The surface potential of the portion (image portion) irradiated with the laser beam 142 from is 0 to −100 V, and an electrostatic latent image corresponding to the black original image component is formed. Therefore, the charger 13 and the first writing unit 14 form an electrostatic latent image forming means. Next, the photosensitive drum 11 is
By the development by the developing device 15, black toner adheres to the image portion and the electrostatic latent image becomes a black toner image. The first developing device 15 includes the developing rollers 151 and 152 and the stirring roller 1 during the developing operation.
53, the stirring blade 154 is rotationally driven by a driving unit, and the developer including the black toner and the carrier in the developing container 155 is stirred by the stirring roller 153 and the stirring blade 154 and conveyed.

The developing sleeve 151 adsorbs the developer, which has been conveyed from the stirring blade 154, by an internal magnet and conveys it with rotation. The developer on the developing sleeve 151 is partially scraped off by a doctor member 156 and adjusted to a constant amount, and then the photosensitive drum 11 and the developing sleeve 151,
After passing through the gap 152, the toner is returned to the inside of the developing container 155, again stirred by the stirring roller 153 and the stirring blade 154, and conveyed. Further, the developer scraped off the developing sleeve 151 by the doctor member 156 is separated by the separator 157.
After that, the toner drops into the developing container 155, is stirred again by the stirring roller 153 and the stirring blade 154, and is conveyed.

While the developer circulates in this manner, the electrostatic latent image on the photoconductor drum 11 is developed by the developer passing between the photoconductor drum 11 and the developing sleeves 151, 152. Toner is replenished to the developer in the developing container 155 from the toner replenishing section 158. Developing sleeve 15
A developing bias voltage of about -600 V is applied from the power source to the reference numerals 1 and 152, and toner adheres to the image portion on the photosensitive drum 11 by the developing device 15, but the photosensitive drum 1
The non-image area on 1 remains around -850V, and toner does not adhere even during development by the developing device 15.

The first charging step of charging the photosensitive drum 11 with the charging charger 13 and the exposure of the photosensitive drum 11 by the first writing unit 14
The exposure step and the first developing step by the first developing device 15 are:
The operation is performed only when the two-color mode or the monochrome mode is selected by the operation unit, and when the mono-color (red / blue) single-color mode is selected by the operation unit, the charger 13, the first writing unit 14, and the first The developing device 15 does not operate, the first charging step to the first developing step are not performed, and the black toner image on the photosensitive drum 11 is not formed.

Next, the photosensitive drum 11 is subjected to a second charging step by the second charging means 16 which is a charger, a second exposure step by the exposure means 17 which is a second writing unit, and a second development step by the second developing device 18. The second charging process to the second developing process are performed only when the two-color mode or the mono-color (red / blue) single-color mode is selected in the operation unit. In the monochrome mode, the charging charger 16 and the second charging process are performed. The second writing unit 17 and the second developing device 18 do not operate, and the second charging step to the second developing step are not performed, and the black toner image on the photosensitive drum 11 advances to the transfer position as it is.

In the two-color mode and the mono-color (red / blue) single-color mode, the photoconductor drum 11 passes through the charging charger 16, and in the second charging step, the charging charger 1 is used.
The charge is applied by 6 and the surface potential becomes about −850 V again. The photoconductor drum 11 is the second writing unit 1.
In the second exposure step of passing through the position 7, the digital recording image information of a color other than black, for example, red or blue, of the original sent from an apparatus not shown is received by the line driver circuit of the second writing unit 17. Is amplified by the laser driver circuit. The digital recorded image information is a multi-valued signal of 8 bits per pixel, and the laser driver circuit energizes the laser diode in response to the digital recorded image information from the line driver circuit.

Laser light emitted from this laser diode is deflected by an optical deflector composed of a polygon mirror, passes through an f-θ lens, is reflected by the mirror, and is image-formed on the photosensitive drum 11. The red or blue original image component is exposed. Here, the photosensitive drum 11
The surface potential of the portion (image portion) irradiated with the laser beam from the second writing unit 17 becomes 0 to −100 V, and an electrostatic latent image corresponding to a red or blue original image component is formed. Therefore, the charger 16 and the second writing unit 18 form an electrostatic latent image forming means.

In the second developing step in which the photosensitive drum 11 passes through the second developing device 18, the image portion of the electrostatic latent image corresponding to the red or blue original image component is developed by the second developing device 18. Red or blue color toner adheres, and the electrostatic latent image becomes a red or blue color toner image. The second developing device 18 includes the stirring rollers 181, 182 and the scooping roller 18 during the developing operation.
3. The developing roller 184 is rotatably driven by the driving unit to agitate and circulate the developer consisting of the red or blue color toner and the carrier in the developing container 185, and the developing roller 184 transfers the developer to the photosensitive drum 11. Supply the photoconductor drum 11
The electrostatic latent image corresponding to the red or blue original image component is developed into a red or blue toner image.

The developing roller 184 receives -750V from the power source.
Front and rear development bias voltages are applied, and the photosensitive drum 11
Color toner adheres to the image portion of the electrostatic latent image corresponding to the red or blue original image component due to development by the developing device 18,
Color toner does not adhere to the non-image portion on the photoconductor drum 11 even when the developing device 18 develops the image.

After passing through the developing device 18, the photoconductor drum 11 is de-charged by the pre-transfer static eliminator 19, and the toner image is transferred from the transfer paper from the paper feeding device by the transfer means 20 which is a transfer / conveying belt device. Is transferred to the transfer material. In this case, the transfer paper is fed from the paper feeding device to the registration roller 21, and the registration roller 21 transfers the transfer paper to the photosensitive drum 1.
The toner image is sent to the transfer means 20 at a timing such that the leading edge of the toner image on the sheet 1 and the leading edge of the transfer sheet are aligned.

The transfer means 20 is a transfer / conveying belt 201.
And the drive roller 20 on which the transfer / transport belt 201 is stretched.
2 and a driven roller 203, a bias roller 204 that comes into contact with the back surface of the transfer / conveyance belt 201, and a cleaning device 205. The drive roller 202 is connected to the transfer motor via a gear and the transfer motor rotates. At the same time, the transfer / transport belt 201 is rotated, and the transfer / transport belt 201 is brought into contact with the photosensitive drum 11 by the belt contact / separation mechanism. Further, the transfer / conveying belt 201 is separated from the photosensitive drum 11 by the belt contact / separation mechanism when the transfer motor is turned off.

Further, the bias roller 204 applies a transfer bias having a polarity opposite to the charging polarity of the black toner and the color toner from the high voltage power source to the bias roller 204 when the transfer sheet is sent from the registration roller 21 to the transfer means 20. The transfer paper is transferred to the transfer / transport belt 201 and the photosensitive drum 1.
In the nip portion (transfer nip portion) with 1, a charge having a polarity opposite to the charging polarity of the toner is supplied from the high-voltage power source via the bias roller 204 and the transfer conveyance belt 201, and the toner image on the photosensitive drum 11 is transferred. It

The transfer / conveying belt 201 includes a high voltage power source 206.
The transfer sheet is electrostatically adsorbed by being applied with a transfer bias from the bias roller 204 and conveyed in accordance with the rotation, and the transfer sheet is transferred with the toner image after the transfer of the toner image.
Electrostatically separated from. The transfer paper not separated from the photosensitive drum 11 is separated by the separating claw 22.
And is conveyed by the transfer conveyer belt 201.

The transfer sheet is conveyed by the transfer conveyer belt 201, separated from the transfer conveyer belt 201 by the curvature of the transfer sheet due to the waist of the transfer conveyer 201, and the toner image is fixed by heat and pressure applied by the fixing device. And then discharged as a copy to the outside. After separating the transfer paper, the transfer / transport belt 201 is cleaned by the cleaning device 205 with the cleaning brush
The residual toner is scraped off by 05a and the cleaning blade 205b. After the transfer paper is separated from the photosensitive drum 11, the cleaning brush 231 and the cleaning blade 232 remove all residual toner from the cleaning device 23, and the process moves to the next image forming step again.

FIG. 7 shows the photosensitive drum 11 and the resist roller.
A conventional drive system for rotationally driving the drive roller 21, the drive roller 202, and the like is shown. The gear 407 rotationally drives the developing device (roller and sleeve) and the photoconductor drum 11 via a power transmission system (not shown), and meshes with the intermediate gear 405. The gear 406 rotationally drives the fixing device (roller thereof) and the paper discharge device (conveyance roller) via a power transmission system (not shown), and meshes with the intermediate gear 405. The gear 404 is the timing belt 41.
Through the power transmission system including 0,
Roller, registration roller) are driven to rotate,
It meshes with the intermediate gear 402. The gear 403 drives the contact transfer unit 20, and meshes with the intermediate gear 402. A sheet feeding device (not shown) includes a clutch for starting and stopping the conveyance of the transfer sheet, and the OFF / ON of the clutch is repeated during the operation of the copying machine.

[0019]

As described above, the copying machine has a developing device, a photosensitive drum, a fixing device, a paper feeding device, etc. as its main units, and each unit has one main motor 400. There are many examples of driving with. In the case of a high speed copying machine (for example, A4 horizontal 50 cpm or more), a plurality of motors such as a developing motor and a paper feeding motor are used for driving in addition to the main motor. The aim of using multiple motors in a high-speed copying machine is to disperse the drive output as the speed increases.

Conventionally, the transfer or charging device has a small driving load by itself, and is driven by the same motor as another unit such as a fixing system and a paper feeding system. However, in the fixing system and the paper feeding system, a load fluctuation occurs when the transfer paper passes, and a rotation fluctuation of the transfer or charging device occurs via the drive motor reduction gear and a rotation fluctuation of the photosensitive drum in contact with them occurs. Of the laser beam 142 caused unevenness in the irradiation of the laser beam 142 and caused jitter. In the case of the conventional example shown in FIG. 7, the vibration at the ON timing and the OFF timing of the registration clutch fixed to the registration roller 21 is transferred through the path of the timing belt 410, the timing pulley 404, the gear 402, the gear 403, and the gear 303. It propagates to the conveyor belt 201, and the moving speed of the belt 201 vibrates. When the belt 201 is in contact with the photoconductor drum 11, the vibration of the belt 201 propagates to the photoconductor drum 11 and the rotational speed of the photoconductor drum 11 vibrates.

FIG. 8 shows the speed fluctuation of the photosensitive drum 11 when the resist clutch is turned on. In the experiment, the transfer / transport belt 201 was connected to the photosensitive drum 1 by the belt contact / separation mechanism.
It was confirmed that the speed fluctuation of the photosensitive drum 11 disappeared when the distance from 1 was removed. This means that if the belt 201 does not vibrate, the photosensitive drum 11 does not vibrate at the above-described rotational speed.

The transfer belt 201 is separated from the photoconductor 11 except during copying. This is because if the transfer belt 201 remains in contact with the photoconductor 11, the plasticizer of the belt 201 moves to the photoconductor 11 and causes a defect on the image. Therefore, as shown in FIG. 9, the driven side gear 303
The clutch drive gear 10 is connected to the intermediate gear 9 to rotate the input shaft (the gear 10 is fixed) of the 1/2 rotation electromagnetic spring clutch. A cam 8 is fixed to the output shaft of the clutch, and when the clutch is energized, the clutch connects the input shaft to the output shaft while the output shaft (cam 8) makes a half rotation, and outputs an output when the rotation makes a half rotation. Separate the axis from the input axis. In this way, the output shaft (cam 8) makes 1/2 rotation in one energization.

For example, when the clutch is energized once in the state shown in FIG. 9, the cam 8 makes a half rotation in the clockwise direction, and as shown in FIG. 10, the lever 8a of the cam 8 rotates counterclockwise about the shaft 5. The lever 7b, which is integral with the lever 7a, also rotates counterclockwise while compressing the compression coil spring 6. The arm supporting the rotating shaft of the driven roller 203 is rotatable about the axis of the driven roller 203, and since this arm is connected to the lever 7b, Similarly, the drive roller 203 rotates counterclockwise and the belt 20
1 is separated from the photosensitive drum 11. That is, the belt 20
1 moves to the retracted position (FIG. 10).

When the clutch is energized once in the state shown in FIG. 10, the cam 8 makes a half turn in the clockwise direction, and the repulsive force of the compression coil spring 6 causes the lever 7b (and the roller 203 supporting roller connected thereto). And the lever 7b) is rotated clockwise so that the belt 201 moves to the photosensitive member 1 as shown in FIG.
Touch 1. That is, the belt 201 moves to the operating position.

To prevent the toner adhering portion 3 (FIG. 10) for checking the toner density during copying from being scraped off by the belt 201, the belt 201 is kept away from the photoconductor 11 until the toner adhering portion 3 passes through. Be done. Toner of attachment section 3
The density is detected by the photo sensor 4.

First copy time (time from when the copy print key is pressed until the copy paper comes out of the machine)
In order to reduce the toner density, the toner adhesion portion 3 for developing density detection is generated, and immediately after the latent image writing (exposure) for image formation is started, the toner adhesion portion 3 is generated during this exposure. The part 3 passes through the driven roller 203. Therefore, during exposure, the toner adhering portion 3 passes through the driven roller 203 and then is driven by a 1/2 rotation electromagnetic spring clutch to drive the roller 2.
03 is driven up to bring the belt 201 into contact with the photoconductor 11, but vibration during clutch operation during exposure propagates to the drive gear 303 via the idler gear 9. When the drive gear 303 vibrates, the photoconductor 11 vibrates through the drive roller 202 and the transfer belt 201 as a relay, and jitter such as density unevenness and image shift occurs in the latent image.

A first object of the present invention is to reduce the rotational unevenness of the contact charging means, and the second object is to reduce the rotational unevenness due to the load fluctuation from the fixing system, the paper feeding system, the developing system and the like and the impact. The purpose of. A third object is to prevent the vibration of the 1/2 rotation electromagnetic spring clutch, which causes the above-mentioned jitter, from shaking the photosensitive drum 11.

[0028]

The first invention of the present application is as follows:
In an image forming apparatus having a visible image carrier (11), an electric motor for driving the carrier that rotationally drives it (400), and a contact charging means (201) in contact with the visible image carrier (11), A driven gear (303) for rotationally driving the contact charging means (201), a drive gear (302) for directly or indirectly meshing with the gear (303) to rotationally drive the gear, and The drive side gear (302)
An electric motor (400) for driving the carrier to rotate
, And an electric motor (3
00), the second invention of the present application is
Visual carrier (11), image forming means (1) for forming a visible image on it
3 to 15), a paper feeding means (2) for feeding the transfer paper to the image bearing member (11).
1), a contact charging means (201) for transferring the visible image on the visible image carrier to the transfer paper, a conveying means for feeding the transfer paper on which the visible image is transferred, and an electric device for driving the paper feeding means and the conveying means. Mode
In an image forming apparatus equipped with a motor, the image bearing member (11) and the contact charging means (201) are rotationally driven, separately from the electric motor for driving the paper feeding means and the conveying means,
An electric motor (43) dedicated to rotationally driving the image bearing member and the contact charging means is provided. The second embodiment of the invention is an electric motor (6) fixed to the rotary shaft (30) of the image bearing member (11) and exclusively used for rotating the image bearing member and the contact charging means (201). Driven gear (40) of the image bearing member, which is rotationally driven by 43), flywheel (44) which is rotationally driven by this, and rotary shaft (50) for rotational drive of contact charging means (201). ), And a driven gear (47) of the contact charging means, which is driven to rotate by the rotation shaft (30) of the image bearing member. A third invention of the present application is to provide a visible image carrier (11), an electric motor for driving the visible image carrier to rotate the same, a contact charging means (201) and the contact charging means (201) to the visible image carrier. Carrier
In an image forming apparatus having a rotary type contact / separation mechanism (8 to 6) that is driven to a retracted position that does not contact with an operating position that contacts (11), a driven-side gear for rotationally driving the contact charging means (201). (303) and a drive force transmission system (402, 403, 303) including a drive side gear (402, 403) for rotationally driving the gear by directly or indirectly meshing with the gear, a system different from the contact and separation mechanism (8 ~
Driven side gear (10) for rotationally driving 6) and the gear
It is characterized in that it is provided with a clutch drive system (35 to 37) including a drive side gear (36) for rotating and driving the gear (10) by directly or indirectly meshing with (10).

In order to facilitate understanding, the symbols of the corresponding elements in the embodiments shown in the drawings and described later are added in parentheses for reference.

According to the first invention, the contact charging means (20
The power transmission system for driving (1) is separated from the power transmission system for driving the image bearing member (11) and other driven elements, and the contact charging means (201) is the dedicated electric motor. Since it is driven to rotate by (300), the rotation speed of the contact charging means (201) does not vibrate due to load fluctuations of the power transmission system that drives the image bearing member (11) and other driven elements, and Since the image carrier (11) is not subjected to velocity vibration, contact charging means (2
Even if (01) is a contact transfer, no jitter is generated in the image formed on the transfer paper.

According to the second aspect of the invention, the power transmission system for driving the image bearing member (11) and the contact charging means (201) is separated from the power transmission system for driving the other driven elements. Since the image carrier (11) and the contact charging means (201) are rotationally driven by the electric motor (43) dedicated to them, load fluctuation due to on / off of driven elements other than these Is not added to the power transmission system of the image carrier (11) and the contact charging means (201), the rotation speed of the contact charging means (201) does not vibrate, and the speed vibration is applied to the image carrier (11). Since it does not occur, jitter does not occur in the image formed on the transfer paper even when the contact charging means (201) performs contact transfer. In one embodiment of the second aspect of the invention, the flywheel (44) absorbs or suppresses the vibration and shock of the image bearing member (11). When another driven element or transfer paper comes into contact with or separates from the image carrier (11), the rotational load of the image carrier (11) fluctuates and the rotation speed easily vibrates. ) Suppress.
Since the contact charging means (201) is driven via the rotary shaft of the visible image carrier (11) whose vibration is suppressed by the flywheel (44), the visible image carrier to the contact charging means (201) is The vibration and shock of (11) are small, and the effect of suppressing the vibration of the contact charging means (201) is high, and even if the contact charging means (201) performs contact transfer, the image formed on the transfer paper will have jitter. -Does not occur.

According to the third invention, the contact charging means (20
The clutch drive system (35 to 37) for contacting and separating (1) with respect to the image bearing member (11) is different from the driving force transmission system (402, 403, 303) for rotationally driving the contact charging means (201). Since it is a system, the vibration due to the clutch drive is
2,403,303) and does not cause velocity vibration to the visible image carrier (11), jitter does not occur in the image even if the clutch is driven during latent image formation (exposure).

Other objects and features of each invention of the present application will be apparent from the following description of embodiments with reference to the drawings.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION

[0035]

【Example】

—First Embodiment— FIG. 1 shows a transfer belt drive system according to an embodiment of the first invention. In this embodiment, the power system for driving the transfer belt 201 of the copying machine shown in FIG. 6 is changed to that shown in FIG. The mechanism excluding the drive system of the transfer belt 201 and the image forming process have already been described with reference to FIG. 6, and thus the description thereof is omitted here, and the power system for driving the transfer belt 201 is described with reference to FIG. To do.

Drive roller 2 with transfer belt 201 stretched
A driven gear 303 fixed to the shaft of No. 02 meshes with a reduction gear (intermediate gear) 302, and this reduction gear 302 is connected to the output shaft of the electric motor 300.
It meshes with 01. The gear 302 has 36 teeth,
Rotation speed is 142.6 rpm. The gear 303 has 30 teeth and rotates at a rotation speed of 171.6 rpm. 40
Reference numeral 0 denotes a main motor, which, like the conventional drive system shown in FIG. 7, rotationally drives the developing device and the photoconductor drum 11 via a gear 407, and rotates the fixing device and the paper discharge device via a gear 406. The sheet feeding device is driven to rotate via the gear 404. 401 is an output shaft (pinion gear) of the main motor 400. The sheet feeding device (not shown) includes a clutch for starting and stopping the conveyance of the transfer sheet,
During operation of the copying machine, the clutch is repeatedly turned off and on. The load fluctuation and speed vibration of the motor 400 and the gear coupled thereto due to this are not applied to the driving roller 202 around which the transfer belt 201 is stretched.

As described above, since the exclusive motor 300 is used for the driving device of the transfer belt 201, there is no influence of the uneven rotation due to the load fluctuation of other units, and the photosensitive drum 11 is not affected.
Even when a flywheel is added to, the inertial mass can be reduced. Although the contact charging means is the transfer belt 201 in this embodiment, it may be a transfer roller, and the contact charging means is replaced with the main charge 13 (FIG. 6) and the photosensitive drum 11. Even if it is a charging roller or a charging belt for contact charging, the driving system may be similarly configured.

-Second Embodiment- FIGS. 2 and 3 show an embodiment of the second invention. In addition,
The whole of this embodiment is the transfer belt 2 of the copying machine shown in FIG.
2 (longitudinal sectional view) and FIG.
It has been changed to that shown in (cross-sectional view). The mechanism other than the drive system of the transfer belt 201 and the image forming process have already been described with reference to FIG. 6, and thus description thereof will be omitted here, and the transfer belt 201 will be described with reference to FIGS.
A power system for driving the motor will be described.

FIG. 2 shows an axial cross section of the drive unit for the photosensitive drum 11 and the transfer unit 20 (FIG. 6). The photoconductor drum 11 has a flange 32 fixed to a pin 31 that is press-fitted into a shaft 30 that is inserted between side plates of the copying machine body.
And is fixed to the other flange 33. The shaft 30 has one end supported by a positioning plate 36 positioned on the front plate 35 of the main body via a bearing 37, and the other end is
The main body rear side plate 38 is supported by bearings 39 and is rotatable. The timing pulley (driven gear of the photosensitive drum 11) 40 is fixed to the shaft 30. The timing belt 41 is looped around the timing pulley 40 and the driving side timing pulley 42a. Reduction gear 42
b and the driving side timing pulley are integrally formed of resin, and the driving force of the driving motor 43 is transmitted to the photoconductor 11 via the reduction gear 42b. A flywheel 44 is screwed to a flange 45 fixed to the shaft 30.

One of the timing belts 45 is attached to the timing pulley 40 and the other is attached to the timing pulley 46, and the timing pulley 46 is integrally formed of resin with a gear. The driving force is transmitted from this gear to the gear 47. The gear 47 is fixed to the shaft 50 via a press fit or a rotation stopper, and the shaft 50 is fixed to the transfer drive roller 52.
It is press-fitted (or pressed against the end face). Further, the shaft 51 has the same processing as the transfer driving roller 52. The shaft 50 is a transfer unit casing 49.
Is supported by a bearing 53, and the shaft 51 is also supported by the bearing 5.
It is supported by the casing 49 via 4. The transfer driving roller 52 is rotatable on bearings 53 and 54. Further, the shaft 51 is supported by a positioning plate 36 which is positioned on the front plate 35 of the main body via a bearing 55, and the shaft 50 is supported by a rear plate 38 of the main body via a positioning flange 48 to position the transfer unit drive section. Are doing.

FIG. 3 is a sectional view of the drive unit for the photosensitive drum 11 and the transfer unit 20 (FIG. 6), which crosses the drum 11. The drive motor 43 drives only the photosensitive drum 11 and the transfer unit 20. The drive direction of the drive motor 43 is rotated clockwise by the reduction gear 42b, transmitted from the timing pulley 42a to the timing pulley 40, and similarly drives the photoconductor 11 clockwise. A flywheel 44 is fixed to the shaft 30. Load fluctuation due to the cleaning blade 232 (FIG. 6) that is in pressure contact with the photoconductor 11 and the gap roller of the developing unit 15 (roller that is abutted against the end of the photoconductor to position the developing unit and the photoconductor) The flywheel 44 cuts the impact of the tip of the paper hitting the surface of the photoconductor. The stable driving force with no rotation unevenness is provided by the timing belt 45 and the timing spool 46 (clockwise).
Is transmitted to the driven gear 47 via a gear and drives the transfer belt 201 via the transfer driving roller 202.
The transfer driving roller 202 rotates counterclockwise, and the transfer belt 201 rotates counterclockwise in a loop formed with the driven roller 203. The rotation of the transfer belt 201 is not affected by the above load fluctuation and impact. In addition, the drive system of the present case is independent of the drive systems of the paper feed system, the fixing system, and the developing system, and is not affected by the impact and load fluctuations generated in those systems.

Although the contact charging means is the transfer belt 201 in this embodiment, it may be a transfer roller, and the contact charging means may be replaced by the main charger 13 (FIG. 6) and exposed. Charging roller for contact charging the body drum 11
A drive system may be similarly configured for a charging belt or a charging belt.

-Third Embodiment- FIG. 4 shows a transfer belt drive system according to an embodiment of the third invention. In this embodiment, the power system for driving the transfer belt 201 of the copying machine shown in FIG. 6 is changed to that shown in FIG. Since the mechanism excluding the drive system of the transfer belt 201 and the image forming process have already been described with reference to FIG. 6, the transfer belt 201 is moved from the operating position (FIG. 4) to the retracted position away from the photosensitive drum 11. Since the clutch drive system for driving and vice versa is the same as that described with reference to FIGS. 9 and 10, description thereof is omitted here, and the transfer belt 201 is referred to with reference to FIG.
A power system for driving the motor will be described.

Reference numeral 400 is a drive motor, and 401 is a motor pinion gear attached to the drive shaft. The motor pinion gear 401 includes two reduction gears 405, 40.
2 meshes. One reduction gear 405 transmits the driving force to the developing device 15 and the cleaning brush 231. The other reduction gear 402 includes a large gear 402a that meshes with the motor pinion gear 401, and a small gear 402b that meshes with the transmission gear 403 coaxially with the large gear 402a. And transmission gear 4
The rotation of the transfer belt 201 is transmitted to the drive gear 303 coaxial with the drive roller 202 via the engagement with the drive roller 03, and the drive force is transmitted to the transfer device 20 to rotationally drive the transfer belt 201.

The gear 10 fixed to the input shaft of the 1/2 rotation electromagnetic spring clutch having the cam 8 fixed to the output shaft is driven by the idler gear 36, the cleaning brush drive gear 35, the idler gear 37 (driving the developing device 15). The driving force is transmitted from the gear 405 via a timing belt or a gear (not shown). ON / OFF of the 1/2 rotation electromagnetic spring clutch is achieved by not connecting the gear 10 fixed to the input shaft of the 1/2 rotation electromagnetic spring clutch and the drive gear 303.
The vibration (impact force) at that time does not propagate to the drive gear 303.

The gears in FIG. 4 are all resin gears and have a low elastic modulus (more elastic than metal gears), and the clutch is ON / O.
The vibration during FF is caused by the gear 1 fixed to the input shaft of the clutch.
From 0 to gears 36, 35, 37, 405,
There is almost no vibration propagating in the order 01, 402, 403, 303 (the vibration due to the clutch is absorbed by the elastic deformation of the gear tooth root in the process of passing through many resin gears).

The vibration transmitted from the gear 10 to the gear 405 due to the moment of inertia of the rotor of the motor 400 causes the motor pin-on gear 401 (only this gear is made of metal: S45).
It is alleviated in C).

FIG. 5 shows a case where the vibration when the 1/2 rotation electromagnetic spring clutch is turned on / off is transmitted by connecting the idler gear 9 (FIGS. 9 and 10: conventional example) from the drive gear 303 and the drive gear. This is a description of the speed fluctuation of the photoconductor drum 11 when it is transmitted without connecting 303 (FIG. 4).

In the third embodiment, the transfer drive gear 303 and the half rotation electromagnetic spring clutch gear 10 are used.
By using different drive trains, the vibration (impact force) at the time of clutch ON / OFF does not propagate to the transfer drive gear 303, and the transfer belt 201 does not vibrate from the gear 303 and the drive roller 202. The vibration of the belt 201 does not shake the photosensitive drum 11 to disturb the image during writing of the latent image (during exposure).

[Brief description of drawings]

FIG. 1 is a side view showing a main part of an embodiment of a first invention of the present application.

2 is a cross-sectional view showing a main part of an embodiment of a second invention of the present application, showing a cross section taken along line 2A-2A of FIG.

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

FIG. 4 is a side view showing a main part of an embodiment of a third invention of the present application.

FIG. 5: ON / OFF of the 1/2 rotation electromagnetic spring clutch when the drive system shown in FIGS. 9 and 4 is used.
6 is a graph showing the speed fluctuation of the photosensitive drum 11 at the time.

FIG. 6 is a cross-sectional view showing a main part of a two-color color copying machine.

7 is a side view showing the configuration of a conventional main drive system used in the copying machine shown in FIG.

8 is a graph showing speed fluctuations of the photosensitive drum 11 shown in FIG. 6 when the paper feed clutch is brought into contact, when the drive system shown in FIG. 7 is used.

[Explanation of symbols]

5: Shaft 6: Compression coil spring 7a, 7b: Lever 8: Cam 9: Idler gear 10: Clutch drive gear 11: Photosensitive drum 12: Static eliminator 13: First charging charger 14: Exposure system 15: First Developing device 16: Second charging charger 17: Exposure device 18: Second developing device 19: Pre-transfer static eliminator 20: Transfer device 30: Shaft 31: Pin 32: Flange 33: Flange 35: Side plate 36: Positioning plate 37 : Bearing 38: Side plate 39: Bearing 40: Timing pulley 41: Timing belt 42a: Timing pulley 42b: Reduction gear 44: Flywheel
Rule 45: Timing belt 46: Timing pulley 47: Gear 48: Flange 49: Case 50: Shaft 51: Shaft 52: Drive roller 53: Bearing 54, 55: Bearing 201: Transfer belt 202: Drive roller -La 203: Driven roller 204: Bias roller 205: Cleaning device 208: Transfer device frame 21: Registration roller 22: Separation claw 23: Cleaning device 300: Transfer belt drive motor 301: Pinion gear 302: Reduction gear 303: Driven gear 400: Main mode
401: Pinion gear 402: Reduction gear 403: Intermediate gear 404-407: Mechanism drive gear

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[Procedure amendment]

[Submission date] January 11, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of drawings]

FIG. 1 is a side view showing a main part of an embodiment of a first invention of the present application.

2 is a cross-sectional view showing a main part of an embodiment of a second invention of the present application, showing a cross section taken along line 2A-2A of FIG.

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

FIG. 4 is a side view showing a main part of an embodiment of a third invention of the present application.

FIG. 5: ON / OFF of the 1/2 rotation electromagnetic spring clutch when the drive system shown in FIGS. 9 and 4 is used.
6 is a graph showing the speed fluctuation of the photosensitive drum 11 at the time.

FIG. 6 is a cross-sectional view showing a main part of a two-color color copying machine.

7 is a side view showing the configuration of a conventional main drive system used in the copying machine shown in FIG.

8 is a graph showing speed fluctuations of the photosensitive drum 11 shown in FIG. 6 when the paper feed clutch is brought into contact, when the drive system shown in FIG. 7 is used.

9 is a side view showing a configuration of a conventional transfer belt drive system used in the copying machine shown in FIG.
1 shows a state in which 1 is placed in the working position.

10 is a side view showing a configuration of a conventional transfer belt drive system used in the copying machine shown in FIG.
01 is shown in the retracted position.

[Explanation of Codes] 5: Shaft 6: Compression Coil Spring 7a, 7b: Lever 8: Cam 9: Idler Gear 10: Clutch Drive Gear 11: Photoreceptor Drum 12: Eliminating Device 13: First Charging Charger 14: Exposure System 15: First developing device 16: Second charging charger 17: Exposure device 18: Second developing device 19: Pre-transfer static eliminator 20: Transfer device 30: Shaft 31: Pin 32: Flange 33: Flange 35: Side plate 36: Positioning plate 37: Bearing 38: Side plate 39: Bearing 40: Timing pulley 41: Timing belt 42a: Timing pulley 42b: Reduction gear 44: Flywheel
Rule 45: Timing belt 46: Timing pulley 47: Gear 48: Flange 49: Case 50: Shaft 51: Shaft 52: Drive roller 53: Bearing 54, 55: Bearing 201: Transfer belt 202: Drive roller -La 203: Driven roller 204: Bias roller 205: Cleaning device 208: Transfer device frame 21: Registration roller 22: Separation claw 23: Cleaning device 300: Transfer belt drive motor 301: Pinion gear 302: Reduction gear 303: Driven gear 400: Main mode
401: Pinion gear 402: Reduction gear 403: Intermediate gear 404-407: Mechanism drive gear

Claims (4)

[Claims] 1. An image forming apparatus having a visible image bearing member, an electric motor for driving the bearing member for rotationally driving the image bearing member, and a contact charging unit for contacting the visible image bearing member, wherein the contact charging unit is rotationally driven. Driven gear for driving, a driving gear for directly or indirectly meshing with the gear to drive the gear, and an electric motor for driving the carrier to rotate the driving gear. An image forming apparatus provided with an electric motor dedicated to rotationally driving contact charging means, which is separate from the above. 2. A visible image carrier, image forming means for forming a visible image on the visible image carrier, sheet feeding means for supplying transfer paper to the visible image carrier, and contact for transferring the visible image on the visible image carrier to the transfer paper. In an image forming apparatus provided with a charging means, a conveying means for feeding a transfer sheet onto which a visible image is transferred, and an electric motor for driving the paper feeding means and the conveying means, a visible image carrier and a contact charging means are rotationally driven. And an electric motor dedicated to rotationally drive the image bearing member and the contact charging means, which is separate from the electric motor for driving the paper feeding means and the conveying means. apparatus. 3. A driven gear for a visible image carrier, which is fixed to a rotary shaft of the visible image carrier and is rotationally driven by an electric motor dedicated to rotationally driving the visible image carrier and the contact charging means. A flywheel rotatably driven, and a driven gear of the contact charging means, which is fixed to a rotation shaft of the contact charging means for rotation driving, and is driven to rotate by the rotation shaft of the image carrier.
The image forming apparatus according to claim 2, further comprising: 4. A visible image carrier, an electric motor for driving the visible image carrier for rotating the same, a contact charging means, and a retracted position where the contact charging means does not come into contact with an operating position in contact with the visible image carrier. In an image forming apparatus having a rotary type contact / separation mechanism to be driven, a driven side gear for rotationally driving the contact charging means and a driving side gear for directly or indirectly engaging with the gear to rotationally drive the gear. And a driven gear for rotationally driving the contact / separation mechanism and a driving gear for rotationally driving the gear by directly or indirectly engaging with the gear. An image forming apparatus comprising a clutch drive system.