JPH04271361A - Photosensitive body driving device - Google Patents

Abstract

PURPOSE:To prevent the influence of vibration caused by the meshing of the teeth of a timing belt and a pulley upon the quality of a toner image in the case of driving a photosensitive drum by using the timing belt in an image forming device where an electrophotographic process is used. CONSTITUTION:In order to drive the photosensitive drum 5 of the image forming device, a transmission system 10 is arranged between a motor 7 and the drum 5. The transmission system 10 is constituted by respectively arranging the pulleys by two in the motor 7 and the drum 5 and arranging two timing belts 11 and 12. The pulley and the belts 11 and 12 are arranged in such a state that the phase of tooth is shifted by 1/2 pitch or 1/4 pitch, so that the vibration caused by the meshing of the teeth of the belt and the pulley is within a scope that it does not influence the quality of the toner image formed on the photosensitive drum in the case of driving the photosensitive body 5.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a photoreceptor drive device in an image forming apparatus using an electrophotographic process, such as a laser printer or an electronic copying machine, and particularly relates to a photoreceptor drive device that uses a timing belt to drive the photoreceptor. The present invention relates to a device that prevents vibrations caused by the meshing of teeth between a timing belt and a timing pulley from affecting the quality of a toner image formed on a photosensitive drum when driving a drum.

0002

2. Description of the Related Art In digital image forming apparatuses using an electrophotographic process, such as electronic copying machines and laser printers, a laser beam is applied to an image carrier such as a photosensitive drum. A toner image is created by writing an image using a beam or the like to form an electrostatic latent image on the photoreceptor drum, and supplying toner from a developing device to the electrostatic latent image. It uses means such as forming. and,
The toner image formed on the photosensitive drum is transferred onto paper by an image transfer section, and the paper carrying the toner image is fixed through a fixing device to create a copy.

Among the image forming apparatuses described above, in electronic copying machines and the like, each device such as a photosensitive drum, fixing device, developing device, paper conveying device, etc. is connected to an individual drive motor, and each device is connected to an individual drive motor. In addition to driving these devices separately, for example, a driving means as disclosed in Japanese Patent Application Laid-Open No. 127762/1984 may be used. In the conventional apparatus described above, a single motor is used to drive the photosensitive drum, the developing device, the fixing device, etc., and a timing belt is used to transmit the driving force.

On the other hand, in digital image forming apparatuses such as laser printers, the drive system for the photosensitive drum is generally configured to use an independent motor. Conditions such as the number of rotations of the photosensitive drum are set accurately to improve image quality. Also,
In order to increase the degree of freedom in arranging the drive device relative to the photoreceptor drum and to reduce costs, the motor and the photoreceptor drum are often connected via a timing belt. .

[0005]

[Problems to be Solved by the Invention] However, in the conventional digital image forming apparatus as described above, there is a problem that if there is unevenness in the rotation of the photoreceptor drum, the rotational fluctuation immediately affects the image quality. be. In other words,
When scanning linearly in the length direction of the photoreceptor drum using a laser beam, if the interval between each scanning line is not maintained constant, the density of the created image may vary. The problem is that unevenness occurs and defective copies are created. However, in the case of devices that use a timing belt as the drive transmission means, the teeth of the timing belt are connected to the timing pulley.
When the teeth mesh with each other, fluctuations in rotation occur depending on the timing of the meshing of those teeth. When the frequency of the rotational fluctuation matches the speed of the photosensitive drum, unevenness in image writing clearly appears.

For example, if the speed of the photosensitive drum is 160 mm
In this case, if a rotational fluctuation frequency of 160 Hz occurs, an image will be formed in an area with poor image quality, and when the speed of the photoreceptor drum is 200 mm, the frequency of 200 Hz has the greatest effect. be. Also, the 6th
As seen in the graph in the figure, in the relationship between amplitude and rotational fluctuation frequency, the upper part of the curve is considered to be an area of poor image quality, and both conditions are set so that other conditions apply. It is necessary to. In order to solve the above problem, it is possible to take measures such as changing the pitch of the belt to change the frequency generated during driving.

However, if the pitch of the teeth of the belt is increased in order to lower the frequency caused by the rotational fluctuations, a problem arises in that the amplitude fluctuations increase, further deteriorating the image quality. On the other hand, if the pitch is made smaller, the transmission torque becomes insufficient, which causes tooth skipping. Therefore, in conventional timing belt drive devices, the pitch of the teeth is made as small as possible, and the transmission device is constructed within a limit that does not cause tooth skipping. It has become impossible to do so. In addition, if the photoreceptor drum is driven using a pulse motor or the like to prevent the effects of vibration frequency, in addition to having a large impact on the manufacturing cost of the image forming apparatus, There are also space-related issues that need to be resolved, such as the increasing size of the equipment.

[0008]

OBJECTS OF THE INVENTION The present invention solves the above-mentioned drawbacks of the conventional device, and the drive mechanism for the photoreceptor drum is replaced by a timing pulley in which two timing belts are provided with teeth of different phases. The object of the present invention is to provide an apparatus that can improve image quality by setting the frequency of rotational fluctuation higher than the defective area of the image.

[0009]

[Means and effects for solving the problems] The present invention provides a timing pulley on each axis of a photoreceptor that forms an image using an electrophotographic process and a motor that drives the photoreceptor. The present invention relates to an image forming apparatus configured to be driven by winding a timing belt around both timing pulleys. In the image forming apparatus of the present invention, two or more timing pulleys are arranged on the shaft of the photoreceptor, and the teeth of the plurality of timing pulleys are arranged in different phases, and -The driving force from
The signal is transmitted to the shaft of the photoreceptor via a plurality of timing belts.

Furthermore, in the apparatus of the present invention, two timing pulleys are attached to the shaft of the photoreceptor with their teeth shifted in phase, and two timing belts are installed between the pulley on the motor side and the pulley on the motor side. can be arranged to transmit the driving force from the motor-side pulley to the shaft of the photoreceptor. moreover,
In the present invention, two gears are meshed with a gear provided on the shaft of the photoreceptor, and each is connected to a timing pulley driven by one timing belt, and the phase of the teeth of the timing pulley is adjusted. It is also possible to use means that can increase the vibration frequency by making the vibration frequency different.

By having the structure described above, the photoreceptor drive device of the present invention allows the use of a plurality of timing belts or the use of a drum shaft gear without significantly changing the structure of the conventional transmission device. Since only a slight change in the drive system is required, there is no significant impact on cost. Further, in the driving method of the present invention, since the fluctuation frequency can be easily set high when driving the photosensitive drum, recording paper with good image quality can be produced.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a photoreceptor driving device of the present invention will be explained according to the illustrated example. In the transmission device 10 of the present invention shown in FIG.
An example of a method of driving the photoreceptor drum 5 using the following is shown. In this embodiment, two timings are provided for the motor-side pulley 13 provided on the shaft 8 of the motor 7 and the drum-side pulley 15 provided on the shaft 6 of the photoreceptor drum 5. Belt 11, 1
2 is wrapped around it. The drum side pulley is shown in Fig. 2(a).
), two drum-side pulleys 15 and 16 are attached to the drum shaft 6, and the drum-side pulley 15
, 16 teeth are arranged with slightly different phases. For example, the phase of the teeth of the drum-side pulley may be shifted by 1/4 pitch as shown in FIG. Arrangements can be made with an arbitrary phase shift, such as by shifting the pitch.

In correspondence with the drum-side pulley shown in FIG. 2, the pulley 13 of the motor shaft 8 in FIG. 1 also has two timing pulleys corresponding to the drum-side pulley. Arrange with shifted phase. Then, one timing belt 11, 12 is arranged for each motor side pulley and drum side pulley, and the two drum side pulleys are used to connect the photosensitive drum. 5.

In the embodiment of the present invention shown in FIG. 1, idlers 17 and 18 are arranged for the two timing belts 11 and 12, respectively, so that the belt tension can be set appropriately. Idler with two idlers
It is supported by the frame 2 of the image forming apparatus via a bracket 19. Furthermore, the motor 7 and the photosensitive drum 5 are
Although it is configured to be supported by the frame 2 using a bearing member (not shown), these supporting means may be of any mechanism as in the case of conventional devices such as electronic copying machines. It can be configured as Incidentally, the pitch of the teeth provided on the timing belt can be arbitrarily set as long as the pitch of the teeth is made as small as possible and tooth skipping does not occur, as in the case of conventional drive mechanisms. Then, as shown in FIG. 2(b) or (c), adjustment is made to arbitrarily change the phase of the teeth in response to the unevenness in density of the toner image formed on the photosensitive drum. As a result, the amplitude and rotational vibration frequency are set within the range of the good image area shown in the graph of FIG. 6, so that the photosensitive drum can be driven.

In another embodiment of the invention shown in FIG.
4 shows a device that drives a photosensitive drum using one timing belt 21 and two timing pulleys placed on the photosensitive drum side, and FIG. 4 corresponds to FIG. 3 above. It is shown as a side view. Figures 3 and 4 above
In the example shown in FIG.
6 is provided, and two gears 2 are provided for the drum shaft gear 26.
3 and 25 are arranged so as to mesh with each other. The gears 23 and 25 are a timing pulley 22 and a timing pulley 22, respectively.
24, and the timing pulleys 22 and 24 are arranged so that the teeth meshing with the timing belt 21 have different phases, similar to the case of the drum side pulley shown in FIG. are doing. The two timing pulleys 2
The timing belt 21 that is wound around the timing belts 2 and 24 is driven by a motor-side pulley 20 provided on the motor shaft 8.
7 and 28 are arranged to apply a predetermined tension to the belt and to enable good transmission of driving force.

By using the drive mechanism configured as described above, for example, in the drive device shown in FIG. 1 or 3, timing pulleys a and b (see FIG. If the rotational fluctuation frequency occurs in a pulse form for each of the pulleys 15 and 16 in Figure 2 or the pulleys 22 and 24 in Figure 3, the combined wave will increase to twice the frequency. I can do it. Then, it is possible to cancel out the primary frequency generated in each drum-side pulley and prevent the rotation of the photosensitive drum from being affected. In addition, when the waveform of the rotational vibration is output as a waveform close to a sine wave, as shown in FIG.
By changing the phase of the teeth of the two drum-side pulleys a and b by 1/2 pitch, it is possible to generate vibrations of opposite phases by the two drum-side pulleys. By creating a state in which the synthesized wave hardly generates vibration, it is possible to prevent the influence of vibration of each drum-side pulley from occurring on the photosensitive drum.

The photoreceptor driving device of the present invention having the above-described configuration can be applied to image forming apparatuses such as laser printers, etc., and can also be applied to digital electronic copying devices. It can be applied to devices such as machines. Furthermore, an image forming mechanism based on a general electrophotographic process can be applied as is to the photosensitive drum using the above-mentioned driving method.

[0018]

Effects of the Invention The photoconductor drive device of the present invention has the above-described configuration, and can be used without significantly changing the configuration of the conventional transmission device, by using a plurality of timing belts, or by using a drum. Since only a slight change is made to the drive system of the shaft gear, there is no significant impact on cost. In addition, in the photoreceptor driving device of the present invention, the photoreceptor drum is driven by increasing the vibration frequency or reducing the amplitude when driving the photoreceptor drum. It is possible to prevent the effects of vibrations and the like from occurring, and to produce recording paper with good image quality.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the configuration of a photoreceptor driving device of the present invention.

FIG. 2(a) is a perspective view showing the configuration of the drum-side pulley of the present invention, and FIGS. 2(b) and 2(c) are explanatory views of the drum-side pulley in different phases.

FIG. 3 is an explanatory diagram of another embodiment of the photoreceptor driving device of the present invention.

FIG. 4 is a side view corresponding to FIG. 3;

FIG. 5 is an explanatory diagram of waveforms appearing on the drum-side pulley and their composite waves.

FIG. 6 is a graph showing conditions for good image quality corresponding to vibration and frequency.

[Explanation of symbols]

1 Image forming device 5 Photosensitive drum 7 Motor 10 Transmission device 11/12 Timing belt 13 Motor side pulley 15/16 Drum side pulley 20 Motor side pulley 21 Timing belt 22/24 Timing pulley 23/25 Gear 26 Drum shaft gear.

Claims (1)

[Claims] 1. A timing pulley is provided on each axis of a photoreceptor that forms an image using an electrophotographic process and a motor that drives the photoreceptor, and the timing pulleys of both are provided.
In an image forming apparatus configured to be driven by a timing belt wrapped around the photoreceptor, two or more timing pulleys are disposed on the shaft of the photoreceptor, and
A photosensitive device characterized in that the driving force from the motor-side pulley is transmitted to the shaft of the photoreceptor via the plurality of timing belts while the phases of the teeth of the plurality of timing pulleys are different. Body drive device.