JPH07210032A - Driving device for rotary image forming body - Google Patents

Abstract

PURPOSE:To smoothly rotate a rotary image forming body at stable speed with stable driving torque by making the rigidity of a rotary body driving system small. CONSTITUTION:A side surface member 40 where an inner peripheral part 40B elastically deformed is formed is attached to the end face of a photoreceptor drum 10, and an engaging hole 40C is provided on the inner peripheral part 40B so as to be engaged with the engaging pin 30P of a driving gear 30. By the driving of the gear 30, the member 40 is elastically deformed by the pin 30P, and the drum 10 is rotated by the reaction of the elastic deformation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotating body of an image output device for forming an image in a digital system by an electrophotographic system, and more particularly to a driving device of a rotating image forming body for rotating a photosensitive body. Further, the present invention relates to a color image forming apparatus which forms a color toner image by arranging a plurality of developing devices on the peripheral surface of an image forming body and superposing monochromatic toner images.

[0002]

2. Description of the Related Art In electrophotographic copying machines, printers, etc., an electrostatic latent image is formed on a surface of a rotating cylindrical photosensitive member or a belt-shaped photosensitive member to form an electrostatic latent image on the surface. Toner is attached to the latent image for development, and the toner image is transferred and fixed on a recording paper to obtain an image.

Here, a cylindrical photosensitive member of an image output device,
That is, the photoconductor drum and the drive roller that drives the belt-shaped photoconductor are referred to as a rotating body.

When the speed of the rotating photoconductor changes due to some influence, jitter or image unevenness occurs in the output image. This is particularly noticeable in the digital electrophotographic technology in which writing on the photoconductor is performed by scanning with a semiconductor laser, and the speed fluctuation of the rotation of the photoconductor becomes the speed fluctuation of the writing system in the sub-scanning direction. This causes a slight deviation in the interval between the two and causes a significant deterioration in image quality.

Particularly, in a color image forming apparatus in which a plurality of developing devices are arranged on the peripheral surface of an image forming body and a color toner image is formed by superposing monochromatic toner images,
Since the color tone of the secondary color formed by two or more toner layers is determined by the appropriate adhesion amount of the toner of each color of each layer, the accuracy of the position of each layer is strictly required. That is, the first mechanism for changing the color tone is that, in the image forming process for the second and subsequent layers, the semiconductor layer or the like exposes the toner layer already formed on the photoconductor,
When the position of what is to be exposed on the toner layer is displaced due to the fluctuation of the speed of the photoconductor, the surface of the photoconductor without the toner layer is exposed. At this time, the surface potential of the photoconductor is lower than that when the toner layer is already present.
The amount of adhered toner after development is larger than that when considered on the toner layer. As a result, the color tone of this portion deviates from the target value. Further, as a second mechanism for changing the color tone, in a digital image output device, an image is often composed of lines which are a continuous body of dots. In this case, the exposure interval is narrowed due to the speed fluctuation of the photoconductor. Since there is a difference in the density of lines or dots between the darkened portion and the widened portion, this appears as color unevenness in the rotational direction of the photoconductor as an image. This significantly deteriorates the quality of the color image.

On the other hand, in the conventional design of a drive system such as a copying machine or a printer, the drive target should be appropriate in relation to the allowable space while satisfying the numerical values such as the line speed and the rotation speed derived from the product specifications. Emphasis was placed on exploring the placement. In other words, how to transmit the power from the power source to the drive target and what to use as a mechanical element for power transmission were of great interest. Therefore, if the unevenness or uneven rotation occurs in the finished product, search for the cause and change the bearing of the drive shaft of the photoconductor to a sintered product, or connect the flywheel to the drive shaft of the photoconductor.
Measures have been taken such as mounting a brake that combines a spring and a friction member on the rotating shaft of the photoconductor, improving gear accuracy, and using helical gears having various torsion angles.

[0007]

The main causes of speed fluctuations of the drive system are speed fluctuations per one rotation of the rotary shaft of the motor, and large absolute values of fluctuation components of one rotation component and one tooth component of the gear. , It was found that these fluctuation components and their harmonic components are amplified or cause a resonance phenomenon in relation to the natural frequency of the drive system.

FIG. 9 shows the speed fluctuation power spectrum of the drive system of the conventional machine. According to this, the fluctuation component due to one gear tooth based on the machine-specific line speed has 176 Hz for the gear directly connected to the motor, 64 Hz for the second shaft, and 25 Hz for the gear directly connected to the drum. As 50Hz
Things are appearing. Further, it has 22 Hz as one rotation component of the gear directly connected to the motor, and 44 Hz appears as its harmonic.

On the other hand, FIG. 10 shows an example of measurement of a transfer function for numerically capturing the natural frequency of the drive system. In this case, the output of the impact excitation hammer and the output of the piezoelectric pickup sensor attached to one end of the photosensitive drum so that the acceleration fluctuation in the rotational direction can be measured are connected to the dual channel FET analyzer, and the Fourier analysis of each Fourier It was carried out by a method of obtaining a spectrum ratio. From this Figure 10,
It can be seen that the peak of the natural frequency of this drive system is near 45 Hz, and the region where the level of the transfer function is high spreads to around 30 to 60 Hz.

FIG. 11 is a graph in which the fluctuation component spectrum and the transfer function are superimposed. As you can see from this figure,
This drive system has a peak of a transfer function, a fluctuation component and its 2
The positions in the frequency domain where the second harmonics exist are overlapping. That is, it was found that this drive system is a system that amplifies the fluctuation component (causes resonance).

Actually, when the actually measured values of three machines having this drive system were examined, the rotation fluctuation of the photosensitive member showed a value of 5 to 8%.

The present invention has been made to solve the above problems. That is, it is possible to prevent uneven rotation and uneven rotation of a photosensitive member of an image output device that performs image formation in a digital method by an electrophotographic method, that is, to keep the writing line interval in the sub-scanning direction constant and to prevent jitter and image unevenness. It is an object of the present invention to provide a driving device for a rotating body that enables high-quality image formation without any problem.

A further object of the present invention is to provide an image forming apparatus for forming a high-quality image in a digital color image without density unevenness or color unevenness occurring in the rotation direction of the photoconductor.

In order to solve the above-mentioned problems, the present invention is premised on reducing the speed fluctuations at the generation source such as a motor or gear, and in addition to this, pays attention to the point that the fluctuation component is transmitted in the drive transmission system. However, the drive device for the rotating body is configured as follows in consideration of the concepts of transfer function, resonance, and natural frequency, and considering how to attenuate the transmitted fluctuation.

First, in order to avoid resonance of the rotating body drive system, it has been decided to prevent the natural frequency of the rotating body drive system from matching the frequency of the fluctuation component transmitted to the rotating body drive system.
In general, the natural frequency f _N is expressed by the following equation.

F _N = (1 / 2π) √ (K / I) (Equation 1) In the formula, K is the torsional rigidity of the drive system, and I is the moment of inertia. The value of f _N can be changed by changing the value of K or I to avoid resonance. From the viewpoint of avoiding resonance, f _N may be increased or decreased relative to the fluctuation component of the rotary drive system. The method of increasing f _N can be realized by increasing K or decreasing I. Also, in order to reduce f _N ,
This can be achieved by increasing I or decreasing K.

FIG. 12 and FIG. 13 show that the natural frequency of the drive system of the data shown in FIG.
Similar to FIG. 11, the measured values of the power spectrum of the rotational fluctuation of the drive system and the transfer function when the values are moved to a smaller value are superposed. Further, FIG. 14 compares the peak values of the transfer function for the above three drive systems. The structural modification for lowering the rigidity of the drive system in FIG. 11 is to reduce the value of the torsional rigidity K of the drive system. Comparing the data of FIGS. 12, 13 and 14, it is conceivable that the torsional rigidity K of the drive system is reduced to move the natural frequency in order to avoid resonance and the natural frequency is lowered. In the case of changing the structure to move to the frequency side, the transfer function becomes smaller as the natural frequency moves. This is because the damping element becomes noticeable due to its flexible structure as the structure is changed to move the natural frequency.
This is considered to be due to a shift to a structure in which the drive system itself absorbs rotational fluctuations. As a result, when the movement of the natural frequency for avoiding the resonance is performed, the structural change to reduce the torsional rigidity K of the drive system is accompanied by the change of the transmission gain of the fluctuation of the rotation speed. It can be seen that it is advantageous and effective in reducing speed fluctuations.

Therefore, in the present invention, by engaging the rotating body and the driving side member with a member having low rigidity, the driving side member can transmit power to the rotating image forming body without transmitting the rotational fluctuation. Aimed at.

[0019]

SUMMARY OF THE INVENTION The above object is to provide a rotary image forming body in which a driving gear for rotationally moving is integrally coaxially coupled to a photoconductor for digitally forming an image by an electrophotographic system. In the driving device, the side surface member of the rotating body is formed such that the outer peripheral portion in contact with the surface of the rotating body is a rigid body and the inner peripheral portion including the shaft portion is a radial elastic body or a viscoelastic body,
A rotation characterized in that an engagement hole is provided in the inner peripheral portion to engage a protrusion member of the drive gear, and the driving force from the drive gear is transmitted to the rotating body via the engagement portion. Rotational image formation in which a drive device for driving an image formation body (first invention) and a drive gear for performing rotational movement are coaxially integrally coupled to a photoconductor that digitally forms an image by electrophotography. In the body drive device, the side member of the drive gear has a rigid outer peripheral portion in contact with the tooth profile, and an inner peripheral portion including the shaft portion formed into a radial elastic body or a viscoelastic body, and is engaged with the inner peripheral portion. A drive device for a rotary image forming body, characterized in that a hole is provided to engage a protruding member of the rotating body, and the driving force from the drive gear is transmitted to the rotating body via the engaging portion ( Second
And an image forming member, a charging unit for charging the image forming member, an exposing unit for forming a latent image on the image forming member, and a toner image for developing the latent image. A plurality of developing means, a transfer means for transferring the toner image onto a transfer body, a cleaning means for cleaning the image forming body after transferring the toner image onto the transfer body, and a front surface of the apparatus main body for opening. A color image forming apparatus having means, wherein a drive gear for rotating the image forming body is integrally connected to the image forming body, wherein a side surface of the image forming body is provided. The member is such that the outer peripheral portion in contact with the surface of the image forming body is formed as a rigid body, and the inner peripheral portion including the shaft portion is formed as a radial elastic body or a viscoelastic body, and an engaging hole is formed in the inner peripheral portion to form a protrusion of the drive gear. Engage the member,
A driving device for a rotating image forming body (third invention), wherein the driving force from the driving gear is transmitted to the image forming body via the engaging portion, and the image forming body and the image forming. Charging means for charging the body, exposure means for forming a latent image on the image forming body, a plurality of developing means for developing the latent image to obtain a toner image, the toner image transfer body A color image forming apparatus comprising: a transfer unit for transferring the toner image to a transfer member; a cleaning unit for cleaning the image forming member after transferring the toner image to the transfer member; and a unit for opening the front surface of the main body of the apparatus. In a drive unit for a rotary image forming body, in which a drive gear for rotating the image forming body is integrally connected, a side member of the drive gear has a rigid outer peripheral portion in contact with a tooth mold and a shaft. Radial bullet around the inner part including the part Body or a viscoelastic body, and an engaging hole is provided in the inner peripheral portion to engage the projection member of the image forming body, and the driving force from the drive gear is applied to the image through the engaging portion. It is achieved by a driving device (4th invention) for a rotating image forming body, which is transmitted to the forming body.

[0020]

By reducing the rigidity K of the rotary body drive system, the natural frequency of the rotary body drive system expressed by the equation (1) decreases, so that the natural frequency and the fluctuation component in the frequency domain can be separated. It is possible to prevent the resonance of the drive system and reduce the rotation speed fluctuation. Furthermore, when the rigidity of the rotary body drive system is reduced, the transmission gain of the rotary body drive system can be reduced by achieving the flexible structure, and the level of speed fluctuation in the rotary body drive can be reduced. As a result, the speed fluctuation of the rotating body is reduced, and the quality of the output image can be greatly improved. Further, the device can be downsized, the cost can be reduced, and the reliability of the entire system can be improved.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Prior to the description of each embodiment of the present invention, the structure and operation of a color image forming apparatus using the above-mentioned rotating body, that is, an image forming body will be described.

In FIG. 1, reference numeral 10 designates a photosensitive drum which is an image forming body, and is formed by coating an OPC photosensitive body on the drum and is grounded and rotated clockwise. Reference numeral 12 denotes a scorotron charger, which applies uniform charge of V _{H to} the peripheral surface of the photosensitive drum 10 by corona discharge by a grid and a corona discharge wire whose potential is held at V _G. Prior to the charging by the scorotron charger 12, a PCL using a light emitting diode or the like to eliminate the history of the photosensitive member until the previous printing.
The surface of the photoconductor is neutralized by exposure using 11.

After uniformly charging the photosensitive member, the image exposing means 13 performs image exposure based on the image signal. Image exposure means
Reference numeral 13 is a reflection mirror 1 via a polygon mirror 131 that rotates using a laser diode (not shown) as a light emitting source, an fθ lens
The optical path is bent by 32 and scanning is performed, and a latent image is formed by the rotation (sub-scanning) of the photosensitive drum 10.
In this embodiment, the character portion is exposed to form an inverted latent image in which the character portion has a lower potential V _L.

Yellow (Y)
Developers each containing a developer composed of toner such as magenta (M), cyan (C), black (K), and a carrier.
14 is provided, and first, the development of the first color is performed by the developing sleeve 141 which contains a magnet and holds the developer and rotates. The developer is a carrier in which a ferrite core is coated with an insulating resin around it, a polyester as a main material, a pigment according to the color, and a charge control agent,
The toner consists of toner to which silica, titanium oxide, etc. have been added.
The layer is regulated to a layer thickness (developer) of 00 to 600 μm and conveyed to the developing area.

The gap between the developing sleeve 141 and the photosensitive drum 10 in the developing area is 0.2 to larger than the layer thickness (developer).
As 1.0mm, D of the AC bias and V _DC of V _AC during this time
The C bias is superimposed and applied. Since V _DC and V _H and the toner are charged with the same polarity, the toner given the opportunity to be separated from the carrier by V _AC does not adhere to the V _H portion, which has a higher potential than V _{DC, and} has a potential higher than V _DC. attached to a lower V _L portion of visualized (reversal development) is carried out.

After the visualization of the first color is completed, the process proceeds to the image forming process of the second color, the uniform charging is performed again by the scorotron charger 12, and a latent image based on the image data of the second color is formed by the image exposing means 13. To be done. At this time, the charge elimination by the PCL 11 performed in the image forming process of the first color is not performed because the toner attached to the image portion of the first color scatters due to the rapid decrease in the potential around the image.

Once again, V is applied over the entire peripheral surface of the photosensitive drum 10.
A latent image similar to that of the first color is formed on the portion of the photoconductor having the _H potential and the image of the first color is not developed, but development is performed again on the portion having the image of the first color. In the portion to be performed, the latent image of V _M ′ is formed due to the light shielding by the toner of the first color and the electric charge of the toner itself, and V _DC
And development is performed according to the potential difference between V _M 'and V _M '. In the overlapping portion of the images of the first color and the second color, the development of the first color is V _L
When the latent image of is formed, the balance between the first color and the second color is lost, so the exposure amount of the first color is reduced and V _H > V _M > V
_It may be an intermediate potential that becomes _L.

An image forming process similar to that of the second color is performed for the third and fourth colors, and a visible image of four colors is formed on the peripheral surface of the photosensitive drum 10.

On the other hand, the recording paper carried out from the paper feed cassette 15 via the half-moon roller 16 is temporarily stopped, and when the transfer timing is adjusted, the recording paper is fed to the transfer area by the rotation operation of the paper feed roller 17.

In the transfer area, the transfer roller 18 is pressed against the peripheral surface of the photosensitive drum 10 in synchronization with the transfer timing.
The supplied recording paper is sandwiched and the multicolor image is transferred at once.

Next, the recording paper is discharged at almost the same time by a separating brush 19 which is brought into a pressure contact state, separated by the peripheral surface of the photosensitive drum 10 and conveyed to a fixing device 20, where the heating roller 201 and the pressure roller 202 are heated and pressed. After the toner is welded by the means, it is discharged to the outside of the apparatus through the paper discharge roller 21. The transfer roller 18 and the separation brush 19 are retracted and separated from the peripheral surface of the photosensitive drum 10 after the recording paper has passed to prepare for the next toner image formation.

On the other hand, the photosensitive drum 10 from which the recording paper is separated is
The residual toner is removed and cleaned by the pressure contact of the blade 221 of the cleaning device 22, and the charge is removed by the PCL 11 and the charger again.
After receiving the electric charge from 12, the next image forming process starts. The blade 221 moves immediately after cleaning the surface of the photoconductor and retracts from the peripheral surface of the photoconductor drum 10.

The features of the functions and performances of the respective equipments constituting the image forming section of the above apparatus will be described below.

(Photosensitive member) The photosensitive drum 10 is stably rotated so that the OPC photosensitive member on the peripheral surface is uniformly charged by the scorotron charger 12. During charging, the grid potential is controlled to stabilize the charging potential.
The specifications of the photoconductor and the charging conditions thereof are set as follows as an example.

Photosensitizer: OPC φ120 Linear velocity 100 mm / sec Negative charging Charging condition: Charging wire: Platinum wire (clad or alloy) is preferably used. _VH- 750V, _VL- 50V (Image exposure) FIG. 2A shows the plane and side of the layout of the image exposure means 13, and FIG. 2B shows the semiconductor laser unit used for the image exposure means 13. It is explanatory drawing of 135.

The OPC photosensitive member on the peripheral surface of the photosensitive drum 10 is negatively charged by the charger 12 and then exposed by the light emission of the semiconductor laser unit 135 of the image exposing means 13 to form an electrostatic latent image.

The image data from the formatter which decodes the printer command is sent to the laser diode (LD) modulation circuit, and when the LD of the semiconductor laser unit 135 emits light by the modulated image signal, the light beam is reflected by the mirror 1.
The scanning lines are synchronized with each other by the beam index 136 via 32 and projected onto the polygon mirror 131.

The polygon mirror 131 reflects the beam light on the polyhedron and scans it. The beam shape of the scanning light is corrected by the fφ lens 133 and the cylindrical lens 134, and then the photoconductor is exposed through the reflection mirror 132. Main scanning is performed to form an electrostatic image.

The beam system of laser light is narrowed down to an equivalent of 600 DPI by an optical system. Therefore, in order to obtain a high quality image, it is necessary to reduce the particle size of the toner. In this embodiment, toner of 8 μm size is used for each color. But most important to the user is the black text quality,
The black toner is preferably a small particle size toner (7 μm to 11 μm).

As the image exposure optical system, for example, a system having the following structure is used.

Polygon mirror: 6 surfaces, rotation number 23600 rpm, air bearing adopted Lens focal length: f = 140 mm Dot clock: 20 MH ₂ beam diameter: approx. 60 × 80 μm (current image) FIG. The toner supplied from the toner box is dropped to the right end of the developing device, and is agitated and mixed with the carrier by a pair of agitating screws 142 that rotate in opposite directions to give a predetermined charge amount (Q / M). Is set to.

The agitated two-component developer is supplied to the supply roller 143.
Is conveyed to the developing sleeve 141 via the layer thickness regulating member 144.
Is transferred to the developing area of the photosensitive drum 10 as a thin layer, and reversal development of the electrostatic latent image is performed under the developing conditions described below.

Current image gap: 0.5 mm toner transport amount: 20-30 mg / cm ² Development bias (AC): 2 KV, 8 KH ₂ (DC): -650 V Development sleeve rotation direction: Positive with respect to photoconductor drum Image density adjustment: Development sleeve rotation speed control or development bias control (forms a patch image on the photoconductor with a laser beam, measures the reflection density after development, and adjusts the image density) Explanation of the image density adjustment To do.

The patch image P is formed by exposing and developing for each color outside the image area of the photosensitive drum 10 every time a predetermined number of prints are completed.

The patch image P formed for each color is shown in FIG.
As shown in (a), the reflectance, that is, the image density is detected by each patch detection unit 100 located on the downstream side of the rotation of the photosensitive drum 10 of each developing device 14, and the detection signal is converted into an output voltage by the detection circuit. It is input to a control logic circuit that controls the bias voltage of the developing bias.

The patch detection unit 100 described above is shown in FIG.
As shown in (b), it is composed of a light emitting portion 101 made of an LED and a light receiving portion 102 made of a phototransistor, and changes the reflectance of the toner image of each patch image P according to the rotation of the photosensitive drum 10. It detects and sends the detection signal to the detection circuit.

The detection signal is input to the developing bias control logic circuit as the output voltage Vout by the processing of the detecting circuit shown in FIG. 5, and the image density is controlled by controlling the developing bias applied to each developing sleeve 141. Adjustment.

The photosensitive drum 10 is driven and rotated by the driving device shown in FIG. The driving device is composed of a driving motor M and a gear group G connected to the driving motor M. The driving gear 30, which is the final gear of the gear group G, directly transmits power to the photosensitive drum 10 or is a side member fixed to the end face. Power is transmitted indirectly via 40.

(Embodiment 1) An embodiment of the first and third inventions of the present invention will be described with reference to FIG.

The side surface member 40 is attached and fixed to the end surface of the photosensitive drum 10 by screwing to be integrated.

In the side member 40, the outer peripheral portion 40A contacting the surface of the photosensitive drum 10 is a ring-shaped rigid body which cannot be deformed, and the inner peripheral portion 40B connecting the central shaft portion and the outer peripheral portion 40A is elastically deformable. A to be a radial elastic or viscoelastic body
It is integrally molded with a resin material such as BS or polycarbonate.

Therefore, when the side member 40 applies a torsional moment to the inner peripheral portion 40B with the outer peripheral portion 40A fixed, only the inner peripheral portion 40B can be elastically deformed in the rotational direction within a predetermined angle. Has become.

The side member 40 is provided with a plurality of engaging holes 40C at predetermined positions on the inner peripheral portion 40B, while the drive gear 30 is provided on the side surface facing the side member 40 at a corresponding position of the engaging hole 40C. A plurality of engaging pins 30P, which are projecting members, are projectingly provided.

The photosensitive drum 10 and the driving gear 30 are assembled at predetermined positions, and the engaging pin 30P is engaged with the engaging hole 40C.
When the drive gear 30 is driven by engaging with the inner peripheral portion 40,
B elastically deforms according to the magnitude of the load on the side of the photoconductor drum 10 to transmit power and rotate the photoconductor drum 10 in the direction of the arrow.

At the time of transmitting power, the inner peripheral portion 40B absorbs a shock or a driving force on the driving gear 30 side and a temporary or steady fluctuation of the driving speed, and as a result, the photosensitive drum 10 always has a constant speed. It is possible to form a high quality image by rotating with.

(Embodiment 2) An embodiment of the second and fourth inventions of the present invention will be described with reference to FIG.

The photosensitive drum 10 is provided with a plurality of engaging pins 10P, which are projecting members, at predetermined positions on the end surface thereof, and one driving gear 30
The side member 50 is attached and fixed to the side surface facing the end surface of the photosensitive drum 10 by screwing.

The side member 50 has a ring-shaped rigid body whose outer peripheral portion 50A contacting the surface of the photosensitive drum 10 is not deformable, and an inner peripheral portion 50B which connects the central shaft portion and the outer peripheral portion 50A can be elastically deformed. A to be a radial elastic or viscoelastic body
It is integrally molded with a resin material such as BS or polycarbonate.

Therefore, when the side member 50 applies a torsional moment to the outer peripheral portion 50A with the inner peripheral portion 50B fixed, the inner peripheral portion 50B is elastically deformed and only the outer peripheral portion 50A is elastically rotated by a predetermined angle. You can do it.

The side member 50 has a plurality of engaging holes 50 at positions corresponding to the inner peripheral portions 50B of the engaging pins 10P of the photosensitive drum 10.
C is provided.

The photosensitive drum 10 and the driving gear 30 are assembled at predetermined positions, and the engaging pin 10P and the engaging hole 50C are provided.
Are engaged with each other to drive the drive gear 30, the inner peripheral portion 50B elastically deforms according to the magnitude of the load on the photoconductor drum 10 side to transmit power, and the photoconductor drum 10 is moved in the arrow direction. Rotate in the direction shown.

During the transmission of power, the inner peripheral portion 50B absorbs a shock or a driving force on the driving gear 30 side and a temporary or steady fluctuation of the driving speed, and as a result, the photosensitive drum 10 always has a constant speed. It is possible to form a high quality image by rotating with.

In each of the above embodiments, the object to be driven is limited to the drum-shaped photoconductor, but in the first and second inventions, the belt-shaped photoconductor is used in addition to the drum-shaped photoconductor. A rotating body, which is used to convey the so-called “rotating roller”, is also included in the driving target.

FIG. 15 shows this embodiment, in which a charging device 312 and a plurality of developing devices 31 containing different color toners are provided around the periphery of a belt photosensitive member 310 having a photosensitive member provided on a belt.
4, a transfer unit 318 and a cleaning unit 322 are provided.
The belt photoreceptor 310 includes a driving roller 320A and a driven roller 320B.
The belt photosensitive member 310 is stretched in a clockwise direction in the figure and charged on the belt photosensitive member 310 by the charger 312, and then is scanned by the exposure unit 313 using a laser to form a latent image. The image forming process of developing by the developing device 314 to form a toner image is repeated a plurality of times, and a multicolor toner image is superimposed on the belt photoconductor 310. The superposed toner images are transferred onto the recording paper separately fed by the transfer unit 318,
The recording paper is separated and then fixed. Also in a color image forming apparatus using such a belt-shaped photosensitive member, by applying the driving device according to the present invention between the driving source and the driving roller 320A, the same effect as that described in the previous embodiment can be obtained. To be

[0065]

According to the present invention, the photosensitive member can be rotated at a stable speed by minimizing the influence of the change of the load or the change of the driving force of the drive system, and as a result, the image quality on the photosensitive member can be improved. An image forming body capable of forming an image excellent in color tone or a rotary image forming body driving apparatus for driving the image forming body is provided.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of an image forming apparatus including a rotary image forming body driving apparatus of the present invention.

FIG. 2 is an explanatory diagram of an image exposure unit of the apparatus.

FIG. 3 is a sectional view of a developing device of the apparatus.

FIG. 4 is an explanatory diagram of image density control in the apparatus.

FIG. 5 is a control circuit diagram.

FIG. 6 is a perspective view showing a drive system of a rotating body.

FIG. 7 is an explanatory diagram of a driving method (first example).

FIG. 8 is an explanatory diagram of a driving method (second example).

FIG. 9 is a graph showing a power spectrum of speed fluctuation of a conventional photoconductor.

FIG. 10 is a graph showing a transfer function of a conventional photoconductor drive system.

FIG. 11 is a graph showing the speed fluctuation power spectrum of the conventional photoconductor and the transfer function of the photoconductor drive system together.

FIG. 12 is a graph showing the transfer function of the photoconductor drive system and the speed fluctuation power spectrum of the photoconductor when the natural frequency is increased.

FIG. 13 is a graph showing the transfer function of the photoconductor drive system and the speed fluctuation power spectrum of the photoconductor when the natural frequency is reduced.

FIG. 14 is a graph showing the peak value of the transfer function of each drive system.

FIG. 15 is a cross-sectional view showing another embodiment of the image forming apparatus provided with the drive device for the rotating image forming body of the present invention.

[Explanation of symbols]

 10 Photoconductor drum 10P, 30P Engagement pin 30 Drive gear 40, 50 Side member 40A, 50A Outer periphery 40B, 50B Inner periphery 40C, 50C Engagement hole

Claims (5)

[Claims] 1. A drive unit for a rotary image forming body, wherein a drive gear for rotating the photosensitive body, which forms an image digitally by an electrophotographic system, is coaxially integrally connected to the photosensitive body. The side member of the drive gear has an outer peripheral portion in contact with the surface of the rotating body as a rigid body, and an inner peripheral portion including a shaft portion as a radial elastic body or a viscoelastic body, and an engaging hole is provided in the inner peripheral portion of the drive gear. A drive device for a rotary image forming body, wherein a protrusion member is engaged with the drive force from the drive gear, and the drive force is transmitted to the rotary body via the engagement portion. 2. A drive device for a rotary image forming body, wherein a drive gear for rotationally moving is integrally coupled coaxially to a photoconductor for digitally forming an image by an electrophotographic system. The side member of the is formed with a rigid outer peripheral portion in contact with the tooth form and a radial elastic body or viscoelastic body including the shaft portion, and an engaging hole is formed in the inner peripheral portion to form a protrusion of the rotating body. A drive device for a rotary image forming body, wherein the drive device is engaged with a member, and the driving force from the drive gear is transmitted to the rotating body via the engaging portion. 3. An image forming body, charging means for charging the image forming body, exposing means for forming a latent image on the image forming body, and for developing the latent image to obtain a toner image. A plurality of developing means, a transfer means for transferring the toner image onto a transfer body, a cleaning means for cleaning the image forming body after transferring the toner image onto the transfer body, and a front surface of the apparatus main body for opening. A color image forming apparatus having means, wherein a drive gear for rotating the image forming body is integrally connected to the image forming body, wherein a side surface of the image forming body is provided. The member has a rigid outer peripheral portion in contact with the surface of the image forming body, and a radial elastic body or viscoelastic body at the inner peripheral portion including the shaft portion. Engage the member, and through the engaging portion A drive device for a rotating image forming body, wherein the driving force from the drive gear is transmitted to the image forming body. 4. An image forming body, charging means for charging the image forming body, exposing means for forming a latent image on the image forming body, and for developing the latent image to obtain a toner image. A plurality of developing means, a transfer means for transferring the toner image onto a transfer body, a cleaning means for cleaning the image forming body after transferring the toner image onto the transfer body, and a front surface of the apparatus main body for opening. A color image forming apparatus having a means, wherein a drive gear for rotating the image forming body is integrally coupled to the image forming body, wherein a side member of the drive gear is provided. Is a rigid member for the outer peripheral portion in contact with the tooth mold, and a radial elastic body or a viscoelastic body for the inner peripheral portion including the shaft portion. An engaging hole is formed in the inner peripheral portion to form a protrusion member of the image forming body. To the drive, and the drive A drive device for a rotating image forming body, wherein a driving force from a moving gear is transmitted to the image forming body. 5. The rotation image forming method according to claim 1, wherein the outer peripheral portion and the inner peripheral portion including the shaft portion are integrally molded of the same resin material. Body drive.