JPH0895327A - Image forming device - Google Patents

Abstract

PURPOSE: To prevent the expansion and contraction of a latent image and a transferred image by eliminating the fluctuation in the circumferential speed of an image carrying member having a latent image forming layer on its outer periphery. CONSTITUTION: A revolving shaft 1 of an ultrasonic motor 7 is extended over a latent image forming region and a photoconductive layer 2 is formed in the latent image forming region. The revolving shaft 1 is supported by a bearing 7a in the ultrasonic motor 7 and a bearing 4 outside the ultrasonic motor 7. Since the image carrying member and a driving source are heretofore connected to each other by a gear or shaft coupling, etc., the shaking of a driving system and the fluctuation in the circumferential speed based on elastic deformation are generated in the part of the photoconductive layer 2 and the fluctuation in the circumferential speed of the image carrying member is thereby nearly entirely eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an image forming apparatus,
The present invention relates to an apparatus for driving an image carrier for forming a latent image in a small size with high accuracy and at a low cost.

[0002]

2. Description of the Related Art FIG. 6 shows a cross section of a functional part of a main part of a conventional example as viewed from the top.

As shown in FIG. 6, a hollow drum-shaped image carrier 3 having a photoconductive layer 2 used in an electrophotographic copying machine, a printer or the like is fitted to a rotary shaft 1 so as to be detachable. It is fixed. The rotating shaft 1 is supported by bearings 4d and 4d.

The rotating shaft 1 is connected to a motor shaft 5a of a motor 5 by a shaft coupling 6. Motor shaft 5a is bearing 5
It is supported by the motor frame via m and 5 m.

For example, a rotating force is generated on the motor shaft 5a of the electric motor 5 by using the electric motor 5 or the like as a drive motor, and the rotating shaft 1 is rotationally driven from the motor shaft 5a through the shaft coupling 6 and installed on the rotating shaft 1. The image carrier 3 having the photoconductive layer 2 thus formed is similarly driven to rotate.

At this time, in many cases, the image carrier 3 is forced to be replaced after a certain period of use due to its product life. Therefore, the image carrier 3 having the photoconductive layer 2 is
A fitting shaft is fixed to the rotating shaft 1 so as to be replaceable.

[0007]

It is desirable that the image carrier having the photoconductive layer rotates without fluctuation. This is because when the image carrier rotates and fluctuates, that is, when the peripheral speed of the image carrier fluctuates, a speed difference occurs between the latent image forming state and the visible image forming state. This is because expansion and contraction occur, the image formed with the latent image and the image after the transfer of the visible image are displaced from each other, and the image is deteriorated.

Here, the peripheral velocity v of the image bearing member can be expressed by the following equation if it is represented by the product of the radius r from the image bearing member rotating center (axial center) to the image bearing member surface and the angular velocity ω of the rotating shaft. Can be expressed as

V = rω (1) Therefore, in order to improve the quality of an image so that the image is less displaced, it is necessary to reduce the fluctuation Δv of the peripheral velocity v of the image carrier. Therefore, it can be said that it is necessary to keep the fluctuation Δω of the angular velocity ω of the rotating shaft as low as possible and also keep the fluctuation Δr of the radius r from the shaft center to the surface of the image carrier as low as possible. If these relationships are shown by equations, they are as follows.

Δv = f (Δr, Δω) (2) To keep the peripheral speed constant, Δv → 0 (3) To set Δv to 0, Δr → 0, Δω → 0 (4) In the conventional example, the following problems occur. 1) When only Δω is set to approximately 0 (when Δr remains) Even if it is possible to suppress the fluctuation Δω of the angular velocity ω of the rotating shaft as low as possible by the rotation control system and the torque transmission system, the photoconductive layer is provided. Since it has a structure that allows replacement of the image carrier,
Since the image bearing member is axially stopped with the fitting backlash with respect to the rotating shaft, a deviation Δr occurs between the center of rotation of the rotating shaft and the center of the image bearing member. Due to these deviations Δr, whirling of the surface of the image carrier with respect to the rotation axis occurs when the shaft rotates, and fluctuations Δv occur in the peripheral speed of the image carrier while the image carrier rotates.

For this reason, a speed difference Δv occurs between when the latent image is formed on the image carrier and when the visible image is transferred, which causes a deviation between the image intended when the latent image is formed and the image after the image is transferred.

In particular, when a plurality of image carriers having photoconductive layers are installed in parallel in order to transfer toners of a large number of colors, as in the case of realizing a color copying machine, so-called "registration". The "deviation" becomes noticeable, and the image quality deteriorates. 2) When only Δr is set to approximately 0 (when Δω remains) Even if it is possible to suppress the variation Δr of the radius r to the surface of the image carrier as low as possible, the image carrier having the photoconductive layer is driven. Therefore, the following problems occur even when the rotary drive source is installed outside. 2-1) When the shaft of the rotary drive source and the rotary shaft having the image carrier are coaxial, as in direct drive, a rotary drive source is installed outside and the rotary shaft is connected by a shaft joint to drive directly. In this case, there is a shaft coupling between the drive shaft (motor shaft) and the rotary shaft having the image carrier, and the axial center between the drive shaft and this rotary shaft is deviated. At this time, the drive shaft is relatively rigidly supported by a bearing or the like inside the drive source, and in many cases, the rotary shaft having the image carrier is also rigidly supported by the bearings inside the apparatus. In order to drive the shaft in a state where there is a deviation in the axial center, that is, in a state where the concentricity between the drive shaft and the rotary shaft cannot be ignored and the shafts are relatively rigidly fixed. The rotational load torque fluctuates due to the elasticity of the shaft, the elasticity of the shaft coupling, and other backlash while absorbing the concentricity deviation, and the fluctuation Δω of the rotational speed of the image carrier occurs. Therefore, a peripheral speed difference Δv between the latent image on the image bearing member and the latent image on the latent image is generated, and a difference between the intended image at the time of latent image formation and the image after the latent image transfer occurs. 2-2) When the shaft of the rotary drive source and the rotary shaft having the image bearing member are not coaxial, such as in the case of driving a gear or a belt. When the rotary shaft having the carrier is not coaxial, a plurality of members (gear, belt, etc.) for associating the two must be interposed. As a result, the mutual stacking of the component accuracies lowers the positional accuracies and the like, which in turn lowers the rotational accuracies, causing the rotational speed fluctuation Δω of the image carrier. Therefore, a peripheral speed difference Δv between the latent image formed on the image bearing member and the latent image formed at the time of transfer of the visible image occurs, and the intended image at the time of latent image formation and the image after the visible image transfer are displaced.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the problem when the image carrier is rotationally driven by direct driving, and to provide an image forming apparatus having an image carrier having a small peripheral speed error.

[0014]

Means and Actions for Solving the Problems A latent image forming layer is formed on the surface of a shaft portion of a drive motor to form an image carrier, and a motor output shaft can be rotated by bearings provided inside and outside the drive motor. By stopping the shaft in this way, the peripheral speed fluctuation of the image carrier due to rotation is minimized, the component structure is simplified, the number of parts is reduced, and the accuracy of parts is reduced. Also, it is possible to realize an image forming apparatus having an image carrier driving mechanism that ensures driving accuracy and reliability.

According to the first aspect of the present invention, a cylindrical image carrier having a latent image forming layer on its outer periphery is provided, and a drive motor for driving the image carrier is disposed coaxially with the image carrier. In the image forming apparatus described above, the rotation axis of the drive motor is extended beyond the latent image forming area, and a latent image forming layer is formed on the surface of the rotation axis in the latent image forming area to form an image carrier. The image forming apparatus.

The second invention of the present invention is the image forming apparatus according to the first invention, wherein the latent image forming layer is a photoconductive layer. A third invention of the present invention is the image forming apparatus as described in the first or second invention, characterized in that the rotation shaft of the motor is supported by bearings provided inside and outside the drive motor.

A fourth invention of the present invention is the image forming apparatus according to any one of the first to third inventions, characterized in that the drive motor is an ultrasonic motor.

A fifth invention of the present invention is the image forming apparatus as described in any one of the first to third inventions, characterized in that the drive motor is an electric motor.

According to a sixth aspect of the present invention, in an image forming apparatus having a plurality of cylindrical image carriers each having a latent image forming layer on its outer periphery, a drive motor is provided for each image carrier. The rotary shaft of each drive motor is extended beyond the latent image forming area, a latent image forming layer is formed on the surface of the rotary shaft in the latent image forming area to form an image carrier, and each drive motor is synchronized. The image forming apparatus is characterized in that it is driven by.

A seventh invention of the present invention is the image forming apparatus according to the sixth invention, characterized in that the peripheral speed of each image carrier is driven in synchronization with one reference speed profile. .

An eighth aspect of the present invention is characterized in that the peripheral speed of one image carrier is used as a reference, and the peripheral speed of each of the other image carriers is synchronized with the reference peripheral speed to drive the image carrier.
The image forming apparatus according to the invention.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 1 shows a horizontal cross-section of a functional part of a main portion as seen from the upper surface of Embodiment 1.

FIG. 2 shows a vertical cross-section of the functional parts of the essential parts as seen from the side surface of the first embodiment.

In a mechanism for rotationally driving an image carrier used in an electrophotographic copying machine or printer, as shown in FIG. 1, the rotary shaft 1 is used as a shaft of an ultrasonic motor 7 which is a drive motor. To extend beyond the latent image forming region, and by directly providing the latent image forming layer, for example, the photoconductive layer 2 on the surface portion on the rotating shaft 1 in the latent image forming region, the image is formed on the rotating shaft itself of the drive motor. It gives the function of a carrier. As the photoconductive layer 2, for example, amorphous silicon,
Amorphous selenium, zinc oxide, titanium oxide, organic photoconductor (OPC), etc. are included.

In order to rotatably support the rotary shaft 1, one end of the rotary shaft 1 is made to enter the inside of the ultrasonic motor 7 and supported by a motor frame via a bearing 7a, and the outside of the ultrasonic motor 7 is supported. The other end of the rotary shaft 1 is supported by the bearing 4.
As the rotating shaft 1, a conductive material such as SUS420 is used.

As shown in FIG. 2, an electric charge is applied by a charger 1b to a rotary shaft 1 which has a photoconductive layer 2 and thus has an image bearing function and is driven to rotate in the direction of the arrow shown in FIG. Exposure is performed by the exposing device 1e shown, a latent image is formed on the photoconductive layer 2 portion on the rotation axis 1, and toner is developed on the latent image by the developing device 1d to form a visible image. Then, the transfer material conveying belt 8 driven by the driving pulley 9 and the driven pulley 10 conveys a transfer material (not shown), and the transfer device 1c transfers the transfer material to the toner, whereby a desired image is transferred. Can be formed. Then, the excess toner remaining on the photoconductive layer 2 portion on the rotary shaft 1 having the function of the image bearing member, which cannot be completely transferred to the transfer material and remains, is cleaned by the cleaning device 1f. Remove from above. The transfer material supporting the toner image is conveyed to a fixing device (not shown) by the transfer material conveying belt 8 moving in the direction of the arrow in the figure, and the toner image is fixed to the transfer material.

Here, since the rotary shaft 1 having the function of the image carrier by having the photoconductive layer 2 is a common member with the ultrasonic motor 7 which is the rotary drive source, the rotational accuracy of the drive source is high. Since the rotation accuracy of the rotating shaft 1 having the photoconductive layer 2 is directly obtained, the controllability of the rotating speed of the ultrasonic motor 7 as a drive source is sufficiently enhanced, the rotating speed fluctuation is sufficiently reduced, and the rotating shaft 1 itself. By sufficiently suppressing the vibration of the rotating shaft 1 by increasing the precision of the above, it is possible to easily secure a highly accurate and stable rotation state of the peripheral speed of the rotating shaft 1 as compared with the conventional example.

Further, since the rotary shaft 1 having the function of the image carrier by having the photoconductive layer 2 is a common member with the ultrasonic motor 7 which is the rotary drive source, the ultrasonic motor which is the drive source. Since there is no deviation between the rotation center of the drive shaft of 7 and the rotation center of the rotation shaft 1, the torque fluctuation that occurs due to the deviation of concentricity when the motor shaft and the rotation shaft are separately connected by a shaft coupling Does not happen.

Further, the rotating shaft 1 having the image carrier function by having the photoconductive layer 2 is provided with the bearings 4 and 7a on the side of the ultrasonic motor 7 which is the rotational drive source and the end portion on the side opposite thereto. Since the bearing is used as a bearing, the number of bearings used can be kept to a minimum compared to the conventional example, and the output shaft of the drive motor and the rotary shaft of the image carrier are supported by two bearings each, and the shaft joint is used. Eliminates concentricity error, backlash, elastic deformation of each axis, runout of the image carrier, etc. that occurs when the output shaft of the drive motor and the rotation shaft of the image carrier intersect or differ as in the case of connection. .

[Embodiment 2] FIG. 3 shows a horizontal cross-section of the functional parts of the essential parts as seen from the upper surface of Embodiment 2.

Except for the ultrasonic motor 7 which is the drive source in the first embodiment shown in FIGS. 1 and 2, the drive source is the electric motor 5 in the same relationship, and the bearing 5a of the electric motor 5 is one end of the rotary shaft 1. I support you. The electric motor 5 may be a DC motor or an AC motor that can rotate at a constant speed. When speed control is necessary, numerical control is performed using a DC servo motor or inverter control is performed using an induction motor.

[Embodiment 3] FIG. 4 shows a horizontal cross-section of the functional parts of the essential parts as seen from the upper surface of Embodiment 3.

FIG. 5 is a vertical cross-sectional view of the functional parts of the essential parts of the four-drum full-color image forming apparatus as seen from the side surface of the third embodiment.

Image forming stations I, II, III,
The images of IV, yellow, magenta, cyan, and black are formed and transferred to the same transfer material.

Image forming stations I, II, III,
IV is the ultrasonic motor 101g, 102 as in the first embodiment.
Rotating shafts 101a, 102a, 103a, 10 extending the output shafts g, 103g, 104g beyond the latent image forming region
4a is provided with the photoconductive layer 2.

In the image forming station I, a charging device 101b, a transfer device 101c, a developing device 101d, an exposing device 101e, and a cleaning device 101f are arranged around a rotating shaft 101a having a photoconductive layer 2.

In the image forming station II, a charging device 102b is provided around a rotating shaft 102a having a photoconductive layer 2.
A transfer device 102c, a developing device 102d, an exposure device 102e, and a cleaning device 102f are provided.

In the image forming station III, the charger 103 is provided around the rotating shaft 103a having the photoconductive layer 2.
b, transfer device 103c, developing device 103d, exposure device 103
e, a cleaning device 103f are provided.

At the image forming station IV, the rotating shaft 104a having the photoconductive layer 2, the charging device 104b, and the transfer device 1 are provided.
04c, a developing device 104d, an exposing device 104e, and a cleaning device 104f.

The conveyor belt 8 wound around the drive pulley 9 and the driven pulley 10 has rotary shafts 101a, 102a, 103.
a and 104a and roller-shaped transfer devices 101c, 102c, 103c and 104c, which are respectively provided opposite to the rotary shafts, are inserted.

In order to form a color image, first, in the image forming station I, a charge is applied by a charger 101b to a rotating shaft 101a having a function of an image carrier by having a photoconductive layer 2. Then, exposure is performed by an exposure device 101e indicated by an arrow, a latent image is formed on the photoconductive layer 2 on the rotating shaft 101a, and a development device 101d is used.
The yellow toner is developed with respect to the latent image to form a yellow visible image. The transfer material conveying belt 8 driven by the drive pulley 9 and the driven pulley 10
Then, a transfer material (not shown) is conveyed, the toner is transferred to the transfer material by the transfer device 101c, and the transfer material is conveyed to the next step. Further, the toner remaining on the photoconductive layer portion 2 formed on the rotating rotary shaft 101a is prepared for new latent image formation by the cleaning device 101f.

A similar process is performed in the next image forming station II, and the magenta toner is transferred onto the transfer material supporting the yellow toner image in an overlapping manner. Then, thereafter, such a process is continuously performed for the image forming stations III and IV so that the toners of yellow, magenta, cyan, and black are transferred to the transfer material in an overlapping manner, and a desired color image is obtained. Can be formed.

At this time, the rotating shaft 1 having the function of each image carrier
By controlling the rotation speeds of 01a, 102a, 103a and 104a, higher quality image can be obtained.

For example, with reference to the peripheral speed of the rotary shaft 1 having the image carrier function of the image forming station I, the peripheral speeds of the rotary shafts having the image carrier functions of the remaining image forming stations II, III and IV are synchronized. By doing so, it is possible to make the images formed by the image forming stations II, III, IV into images that follow the images formed by the image forming station I, and the images formed by the respective image carrier sets can be It is possible to configure a device capable of preventing the deviation of the image and forming a high-quality color image.

In such an apparatus structure, the reference of the peripheral speed of the rotary shaft is not limited to the image forming station I, but the image forming stations II and II.
It may be either I or IV.

As shown in FIG. 4, the rotary shafts 101a, 102a of the image forming stations I, II, III, IV,
Similar to the ultrasonic motors of the first embodiment, one ends of 103a and 104a are ultrasonic motors 101g, 102g and 103, respectively.
g, 104 g. This ultrasonic motor 101
In order to rotate g, 102g, 103g, and 104g synchronously, ultrasonic waves with the same frequency and the same amplitude and a phase difference π
It may be added over the phase B. Further, the gear shift can be performed by the excitation frequency deviated from the resonance frequency.

These ultrasonic motors can also be changed to electric motors. A DC servomotor is suitable for the electric motor. For example, the DC servomotor of the image forming station I is driven by the C-axis numerical control device, and an encoder is connected to the end of the rotary shaft 101a of the image forming station I. To the C-axis numerical control device, and with the C-axis numerical control device, another image forming station II,
The DC servomotors III and IV can rotate at the same speed.

[Fourth Embodiment] In the fourth embodiment, the speed of the rotary shaft is controlled as follows in a configuration substantially similar to FIGS. 4 and 5 showing the third embodiment.

A rotary shaft 101a having the function of each image carrier,
The peripheral speed of 102a, 103a, 104a is made into a desired rotational speed profile (the rotational speed of the rotating shaft changes while the rotating shaft makes one rotation, and therefore the peripheral speed of the rotating shaft also changes during one rotation of the rotating shaft). The rotational speeds of the rotary shafts 101a, 102a, 103a, 104a having all the image carrier functions are set and rotationally driven in accordance with the rotational speed profile, so that the accuracy of parts, assembly accuracy, etc. It is possible to configure a device capable of forming a high-quality color image by adjusting the peripheral speed fluctuation of the rotating shaft caused by the variation and preventing the deviation between the images formed by the respective image carrier sets.

At this time, the rotary shafts 101a, 102a, 10
The rotation speed profiles of 3a and 104a are the rotation axis 10
It may be set for each of 1a, 102a, 103a, 104a, or may be set with reference to one certain rotation axis speed profile. With such a desired rotation speed profile, each rotation axis is driven by a DC servo motor, and each DC servo motor is driven by a four-axis numerical control device, and the rotation speed of each rotation axis is stored in the memory of the four-axis numerical control device. This can be achieved by programming and inputting the profile. In the above, when the rotational speed profile is based on one rotational speed profile for each of the rotating shafts 101a, 102a, 103a, 104a, a numerical control device for uniaxial control is sufficient.

According to the present embodiment, since the rotation shaft is the image bearing member and the output shaft of the drive motor, when the rotation speed is changed by the rotation speed profile, there is rattling of the drive system and a rotation angle due to elastic deformation. Since there is no error,
In particular, when numerical control is performed, highly accurate rotation control can be realized, each rotation shaft can be rotated at a desired rotation speed, and registration deviation can be eliminated.

In the above embodiments, the mechanism for rotationally driving the image carrier has been described based on the case of being used in an image forming apparatus such as an electrophotographic copying machine or a printer. The image forming means is not limited to the electrophotographic method, and any image forming means may be used.

[0054]

According to the first aspect of the present invention, the rotary shaft of the drive motor is extended beyond the latent image forming region, and the latent image forming layer is formed on the surface of the rotary shaft in the latent image forming region. Therefore, it is possible to minimize the speed fluctuation of the surface of the image carrier due to the rotation.

The parts structure is simplified and the number of parts is reduced,
It is possible to realize an image forming apparatus having an image carrier driving mechanism that secures driving precision and reliability while reducing component cost by reducing the stacking of precision of components.

In the second invention of the present invention, since the latent image forming layer is a photoconductive layer in the first invention, an image forming apparatus such as an electrophotographic apparatus or a printer for inputting an image as light to form an image. It is suitable to be applied to.

A third invention of the present invention is the bearing provided inside and outside the drive motor in the first or second invention,
Since the rotation shaft of the motor is supported, the motor shaft of the drive motor is supported by the two bearings, and the rotation shaft of the image carrier is supported by the two bearings, as compared with the conventional example. In addition, it is sufficient to support the rotating shaft with only two bearings, so that the frictional resistance of the bearings can be reduced and the power of the drive motor can be reduced.

The fourth invention of the present invention is suitable for driving an image carrier having a low peripheral speed, since the drive motor is an ultrasonic motor in any one of the first to third inventions.

The fifth aspect of the present invention is based on any one of the first to third aspects of the invention, in which the drive motor is an electric motor. C. Numerical control drive as a servo motor or inverter control as an induction motor can facilitate speed control.

According to a sixth aspect of the present invention, in an image forming apparatus having a plurality of cylindrical image carriers, each image carrier is provided with a drive motor, and the rotation axis of the drive motor is set to a latent image forming area. Since the latent image forming layer is formed on the surface of the rotary shaft in the latent image forming region and the drive motors are driven in synchronization with each other as image carriers, the rotary shaft of the drive motor is Since it is a body, there is no concentricity, backlash, and scratches compared to the case where the drive motor and the image bearing body are connected by a shaft joint, and the speed fluctuation can be minimized, so the deviation of the synchronous drive is minimal. The deviation of the ratio can be made extremely small.

In the seventh invention of the present invention, in the sixth invention, the peripheral speed of each image carrier is driven in synchronism with one reference speed profile, so that there is no rattling in the drive system. The elastic deformation of the drive system is so small that it can be ignored, and each image carrier can be accurately rotated according to the speed profile.

In the eighth invention of the present invention, in the sixth invention, the peripheral speed of one image carrier is used as a reference, and the peripheral speeds of the other image carriers are synchronized with the reference peripheral speed to drive the image carrier. Therefore, there is no play in the drive system, and the elastic deformation of the drive system is so small that it can be ignored, and the peripheral speed of one image carrier accurately matches the peripheral speed of the other image carrier. effective.

[Brief description of drawings]

FIG. 1 is a horizontal cross-sectional view showing a functional part of a main part of a first embodiment of the present invention viewed from an upper surface part.

FIG. 2 is a vertical cross-sectional view showing the functional components of the essential parts of the first embodiment of the present invention as viewed from the side surface.

FIG. 3 is a horizontal cross-sectional view showing a functional part of a main part when a second embodiment of the present invention is viewed from an upper surface part.

FIG. 4 is a horizontal cross-sectional view showing a functional part of a main part of a third embodiment of the present invention when viewed from the upper surface part.

FIG. 5 is a vertical cross-sectional view showing a functional part of a main part of a third embodiment of the present invention viewed from a side surface.

FIG. 6 is a horizontal cross-sectional view showing a functional part of a main part when the conventional example is viewed from an upper surface part.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 rotating shaft 1b charger 1c transfer device 1d developing device 1e exposure device 1f cleaning device 2 photoconductive layer 3 image carrier 4 bearing 5 electric motor 6 joint 7 ultrasonic motor 8 transfer material conveying belt 9 drive pulley 10 driven pulley 101a rotation Shaft 101b Charging device 101c Transfer device 101d Developing device 101e Exposure device 101f Cleaning device 102a Rotating shaft 102b Charging device 102c Transfer device 102d Developing device 102e Exposure device 102f Cleaning device 103a Rotating shaft 103b Charging device 103c Transfer device 103d Developing device 103e Cleaning device 104a Rotating shaft 104b Charging device 104c Transfer device 104d Developing device 104e Exposure device 104f Cleaning device

Claims (8)

[Claims] 1. An image forming apparatus comprising a cylindrical image carrier having a latent image forming layer on its outer periphery, and a drive motor for activating the image carrier coaxially with the image carrier. An image forming apparatus, wherein a rotation shaft of a motor is extended beyond a latent image forming region, and a latent image forming layer is formed on a surface of the rotation shaft in the latent image forming region to form an image carrier. 2. The image forming apparatus according to claim 1, wherein the latent image forming layer is a photoconductive layer. 3. The image forming apparatus according to claim 1, wherein a rotation shaft of the motor is supported by bearings provided inside and outside the drive motor. 4. The image forming apparatus according to claim 1, wherein the drive motor is an ultrasonic motor. 5. The image forming apparatus according to claim 1, wherein the drive motor is an electric motor. 6. An image forming apparatus having a plurality of cylindrical image bearing members each having a latent image forming layer on the outer periphery thereof, wherein each image bearing member is provided with a drive motor, and each drive motor is The rotary shaft extends beyond the latent image forming area, a latent image forming layer is formed on the surface of the rotary shaft in the latent image forming area to form an image carrier, and each drive motor is driven in synchronization. Image forming apparatus. 7. The image forming apparatus according to claim 6, wherein the peripheral speed of each image carrier is driven in synchronization with one speed profile serving as a reference. 8. Based on the peripheral speed of one image carrier,
7. The image forming apparatus according to claim 6, wherein the image forming apparatus is driven by synchronizing the peripheral speed of each of the other image carriers with the reference peripheral speed.