JP2000352898A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce or eliminate the positional deviation of an AC component with an inexpensive and simple structure in an image forming device. SOLUTION: This device is provided with a photoreceptor drum 1, an electrifying means for uniformly electrifying the surface of the drum 1, an exposure means for forming an electrostatic latent image by radiating exposure light beam corresponding to image data onto the electrified drum 1, a developing means developing the electrostatic latent image formed on the drum 1, a transfer means transferring a toner image developed on the drum 1 to transfer material, a driving spline 17 to which driving force generated by a driving motor is transmitted, and a driven spline 18 attached to the rotary shaft of the drum 1, positioned in the radial direction by the spline 17 and coupled with the spline 17, and transmitting the driving force of the driving motor transmitted from the spline 17 to the drum 1 so as to rotate the drum 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a multiplex image forming apparatus for forming a composite image by superimposing image information on a transfer material using electrophotographic technology or the like.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus employing an electrophotographic technique, an electrophotographic photosensitive member as an image carrier is charged by a charger, and the photosensitive member is irradiated with light according to image information. 2. Description of the Related Art A latent image is formed, and the latent image is developed by a developing device, and a visualized toner image is transferred to a sheet material or the like to form an image.

On the other hand, a plurality of image carriers on which such a series of image forming processes are developed in accordance with colorization of an image are provided, and each color image of a cyan image, a magenta image, a yellow image, and preferably a black image is provided. Is formed on each image carrier, and a tandem-type image forming apparatus that forms a full-color image by superimposing and transferring each color image on a transfer material at a transfer position of each image carrier has been proposed.

Since such a tandem type multiple image forming apparatus has an image forming unit for each color,
This is advantageous for speeding up. A technical problem is how to properly perform registration (registration) of each image formed by different image forming units. This is because the shift of the image forming positions of the four colors transferred to the sheet material eventually appears as a color shift or a change in color tone.

By the way, as shown in FIG. 12, the type of positional deviation of the transferred image is a positional deviation (top margin) in the scanning line writing direction (the direction of arrow A in the figure) with respect to the transfer material 9 (FIG. a)), misalignment (left margin) in the scanning direction (arrow B direction orthogonal to arrow A direction in the figure)
(FIG. 12 (b)), the displacement in the oblique direction (FIG.
(C)), there is a deviation of the magnification error (FIG. 12 (d)), and in reality, a superposition of these four types of deviations appears.

The main cause of the displacement is shown in FIG.
In the case of the top margin shown in FIG. 12A, the image writing timing of each image forming station is shifted.
In the case of the left margin (b), it is a shift of the writing timing of each image of each image forming station, that is, the shift of the scanning start timing in one scanning line. In the case of the inclination shift in the oblique direction in FIG. 12C, it is the mounting angle shift of the scanning optical system or the angle shift of the rotation axis of the image carrier. In the case of the shift due to the magnification error in FIG. This is due to the deviation of the scanning line length due to the error of the optical path length from the scanning optical system of each image forming station to the image carrier.

In order to eliminate the four types of shifts as described above, the shift amounts of the top margin and the left margin are adjusted by adjusting the scanning timing of each color. With respect to the magnification error deviation and the inclination deviation, the mirror surfaces of the three folding mirrors 101, 102, and 105 installed in the optical path of each image forming station shown in FIG. Mirror 10
Correction is made by adjusting actuators 1 and 102 independently in the directions of arrows M and N by actuators 103 and 104, respectively.

As an actuator for adjusting the folding mirrors 101 and 102, a linear step actuator or the like provided with a step motor as a driving source that moves linearly stepwise is used.

However, the above-described four types of positional deviation adjustments are intended for DC components that always have a fixed amount of deviation, and it is difficult to correct AC components that fluctuate with a certain period.

Particularly, a problem with the tandem type image forming apparatus is the displacement of the AC component. The displacement of the AC component in the scanning direction (the direction of arrow B in FIG. 12) as shown in FIG. When a ladder pattern is printed, the pitch of the ladder fluctuates with a certain period.

The causes of the displacement of the AC component in the scanning line writing direction (the direction of arrow A in FIG. 12) include, for example, uneven rotation of the image carrier due to eccentricity of the gear driving the image carrier, and rotation of the transfer material. There is unevenness in the rotation of the transfer material due to variations in thickness in the direction, eccentricity of the transfer member drive roller shaft, and eccentricity of the gear driving the drive roller. .

For example, the positional deviation caused by the eccentricity of the gear for driving the image carrier or the eccentricity of the transfer member driving roller is short, and occurs repeatedly in the transfer member. Further, the displacement caused by unevenness in the thickness of the transfer body is a long period,
Occurs repeatedly with each rotation.

If the ladder patterns of a plurality of image carriers are superimposed and printed without any correction, the magnitudes and phases of the AC components of the ladder patterns of the plurality of image carriers differ. Is shifted and transferred to the transfer body,
A so-called color shift occurs.

In particular, a large displacement of the AC component in the scanning line writing direction occurs due to uneven rotation of the image carrier.

For this reason, in a conventional tandem-type multiplex image forming apparatus, for example, as disclosed in Japanese Patent Publication No. 4-31590, a means for detecting uneven rotation (not shown) is provided on the image carrier. To detect the period and phase of rotational unevenness,
The displacement of the AC component is corrected by controlling the rotation speed of a driving unit (not shown).

In Japanese Patent Application Laid-Open No. 9-146329, a detection pattern (not shown) is transferred onto a transfer material and detected by a detection means in order to detect rotation unevenness of the image carrier. There has also been proposed a technique of detecting rotational unevenness by using a control unit and controlling the rotational speed of a driving unit (not shown) of the image carrier to correct the displacement of the AC component.

The above-described displacement of the AC component causes jitter and uneven density even on a single-color image, thereby deteriorating the image quality. Therefore, the displacement of the AC component causes a problem not only in the multiplex image forming apparatus but also in the monochromatic image forming apparatus.

[0018]

However, in the above-described conventional technique for correcting the displacement of the AC component, there is a problem in that the detecting means such as an encoder or the like for correcting the rotational unevenness is used to detect the rotational unevenness of the image carrier. However, there is a problem that a complicated control means is required, which leads to an increase in the size of the apparatus and an increase in cost.

Further, the technique of transferring a detection pattern and detecting the same requires a long detection pattern to detect the period and phase of uneven rotation, and has a problem that toner consumption increases.

The problem of the displacement of the AC component is very serious particularly when a high-quality image is formed in a digital color multiplex image forming apparatus.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus capable of reducing or eliminating a displacement of an AC component with a low cost and a simple structure.

[0022]

In order to solve this problem, an image forming apparatus according to the present invention comprises a photosensitive member, charging means for uniformly charging the surface of the photosensitive member, and Exposure means for irradiating an exposure light beam corresponding to image data to form an electrostatic latent image, developing means for visualizing the electrostatic latent image formed on the photoconductor, and toner developed on the photoconductor A transfer unit for transferring an image to a transfer material, a drive transmission unit to which a driving force generated by a drive motor is transmitted, and a drive transmission unit mounted on a rotating shaft of the photosensitive member and positioned in a radial direction by the drive transmission unit And a drive follower for transmitting the driving force of the drive motor transmitted from the drive transmission unit to the photoconductor and rotating the photoconductor.

As a result, the rotation center of the drive transmission unit and the rotation center of the drive follower unit coincide with each other, thereby reducing or eliminating angular velocity fluctuations.
It is possible to reduce or eliminate the transfer position shift of the C component.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a photosensitive member, a charging means for uniformly charging the surface of the photosensitive member, and an exposure corresponding to image data on the charged photosensitive member. Exposure means for irradiating light rays to form an electrostatic latent image, developing means for visualizing the electrostatic latent image formed on the photoconductor, and transfer of the toner image developed on the photoconductor to a transfer material Transfer means, and a drive transmission unit to which a drive force generated by a drive motor is transmitted, and mounted on the rotating shaft of the photoreceptor, positioned in the radial direction by the drive transmission unit and connected to the drive transmission unit,
An image forming apparatus comprising: a drive driven unit that transmits a driving force of a drive motor transmitted from a drive transmission unit to a photoconductor and rotates the photoconductor, wherein a rotation center of the drive transmission unit and a rotation center of the drive driven unit are rotated. And angular velocity fluctuations are reduced or eliminated, and AC is achieved under a low-cost and simple structure.
This has the effect of making it possible to reduce or eliminate transfer misregistration of components.

According to a second aspect of the present invention, in the first aspect of the invention, the outer peripheral portion of the drive transmitting portion and the inner peripheral portion of the drive driven portion are engaged with each other to form the driven driven portion. Is an image forming apparatus that is positioned in the radial direction, the rotation center of the drive transmission unit and the rotation center of the drive driven unit can be more accurately matched, so that the angular velocity fluctuation can be reduced or eliminated, This has the effect that it is possible to reduce or eliminate the transfer displacement of the AC component.

According to a third aspect of the present invention, in the second aspect of the present invention, the drive transmission unit and the drive follower are:
An image forming apparatus in which the root of the drive transmission unit and the tip of the drive follower are engaged with each other, and the drive transmission unit and the drive follower can be smoothly and smoothly engaged with each other.
The rotation center of the drive transmission unit and the rotation center of the drive follower can be accurately matched to reduce or eliminate angular velocity fluctuations, thereby reducing or eliminating the transfer displacement of the AC component. Have.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the valley diameter of the spline teeth on the drive driven portion side is determined in the radial direction by the peak diameter of the spline teeth on the drive transmission portion side. The image forming apparatus is capable of smoothly and smoothly engaging the drive transmission unit and the drive driven unit, and accurately aligning the rotation center of the drive transmission unit with the rotation center of the drive driven unit. This has the effect of reducing or eliminating angular velocity fluctuations and reducing or eliminating transfer displacement of the AC component.

According to a fifth aspect of the present invention, in the image forming apparatus according to the fourth aspect, the spline teeth have an involute tooth profile, and the driving force of the drive transmission unit is smoothly applied to the drive driven unit. In addition, the rotation center of the drive transmission unit and the rotation center of the drive follower unit can be accurately matched to reduce or eliminate angular velocity fluctuations. Can be reduced or eliminated.

According to a sixth aspect of the present invention, there is provided an image forming apparatus according to the fourth aspect, wherein the spline teeth are formed in a parallel tooth shape, and the rotational torque is applied in the radial direction as a photosensitive force. The center of rotation of the body is prevented from shifting,
Furthermore, the rotation center of the drive transmission unit and the rotation center of the drive driven unit can be accurately matched to reduce or eliminate angular velocity fluctuations, thereby reducing or eliminating the transfer position deviation of the AC component. Having.

According to a seventh aspect of the present invention, in the first aspect of the present invention, the driving force of the driving force from the driving motor to the photosensitive member via the driving transmitting portion and the driving driven portion is provided. This is an image forming apparatus that uses a timing belt for transmission, which can reduce or eliminate rotational unevenness of the drive system itself and reduce or eliminate angular velocity fluctuations of the photoconductor, and reduce the transfer position shift of the AC component. Alternatively, it has the effect of being able to eliminate it.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. In these drawings, the same members are denoted by the same reference numerals, and duplicate description is omitted.

(Embodiment 1) FIG. 1 is an explanatory view showing the structure of an image forming apparatus according to Embodiment 1 of the present invention, and FIG. 2 is a perspective view showing the structure of a drive unit in the image forming apparatus of FIG. 3 is a perspective view showing the drive unit and the photosensitive drum of FIG. 2, FIG. 4 is a perspective view showing a main part of FIG. 3, and FIG.
FIG. 6 is an explanatory diagram showing a meshing state between the driving spline and the driven spline, and FIG. 6 is an explanatory diagram showing a radial play in a state where the driving spline and the driven spline are connected;
FIG. 7 is an explanatory diagram showing an angular velocity variation due to a shift of the rotation center between the driving spline and the driven spline, and FIG. 8 is an explanatory diagram showing transmission of the angular velocity by the driving spline and the driven spline in the image forming apparatus of the first embodiment. .

As shown in FIG. 1, the image forming apparatus according to the present embodiment is a multiplex image forming apparatus in which four image forming stations Pa, Pb, Pc and Pd constituting a drive unit 2 are arranged. Image forming stations Pa, P
b, Pc, and Pd have photoconductor drums (photoconductors) 1a, 1b, 1c, and 1d as image carriers.

Around the photosensitive drums 1a, 1b, 1c, 1d, charging means 3a, 3b, which uniformly charge the surface of each of the photosensitive drums 1a, 1b, 1c, 1d to a predetermined potential.
3c, 3d, charged photosensitive drums 1a, 1b, 1
Exposure light rays 4 corresponding to image data of a specific color on c and 1d
Exposure means 4 for irradiating K, 4C, 4M, 4Y to form an electrostatic latent image, developing means 5a for visualizing the electrostatic latent images formed on photosensitive drums 1a, 1b, 1c, 1d, 5b, 5
c, 5d, transfer means 6a, 6b, 6c, 6d for transferring the toner image visualized on the photosensitive drums 1a, 1b, 1c, 1d to an endless intermediate transfer belt (intermediate transfer body) 8.
After transferring the toner images from the photoreceptor belts 1a, 1b, 1c, 1d to the intermediate transfer belt 8, the photoreceptor belts 1a, 1
Cleaning means 7a, 7b, 7c, 7d for removing residual toner remaining in b, 1c, 1d are arranged respectively.

Here, the exposing means 4 comprises the photosensitive drum 1
They are arranged with a predetermined inclination with respect to a, 1b, 1c and 1d. The intermediate transfer belt 8 rotates in the direction of arrow A in the illustrated case. In the image forming stations Pa, Pb, Pc, and Pd, a black image, a cyan image, a magenta image, and a yellow image are formed, respectively. The photosensitive drums 1a, 1b, 1c,
The single-color images of each color formed in 1d are sequentially superimposed and transferred onto the intermediate transfer belt 8 to form a full-color image.

At the lower part of the apparatus, there is provided a paper feed cassette 11 in which a sheet material 10 such as printing paper is stored.
Then, the sheet material 10 is sent out from the sheet feeding cassette 11 to the sheet conveying path one by one by the sheet feeding roller 9.

The intermediate transfer belt 8 contacts the outer peripheral surface of the intermediate transfer belt 8 for a predetermined amount on the paper transport path.
A sheet material transfer roller 12 for transferring the color image formed thereon to the sheet material 10, and a fixing device for fixing the color image transferred on the sheet material 10 to the sheet material 10 by the pressure and heat associated with the pinching rotation of the roller. A vessel 13 is arranged.

In the multiplex image forming apparatus having such a configuration, first, a latent image of a black component color of image information is formed on the photosensitive drum 1a by the charging unit 3a and the exposing unit 4 of the image forming station Pa. This latent image is visualized as a black toner image by a developing unit 5a having black toner by a developing unit 5a, and is transferred as a black toner image onto the intermediate transfer belt 8 by a transfer unit 6a.

On the other hand, while the black toner image is being transferred to the intermediate transfer belt 8, a latent image of a cyan component color is formed in the image forming station Pb.
Thus, the cyan toner image by the cyan toner is visualized.
Then, the cyan toner image is transferred by the transfer means 6b of the image station Pb to the intermediate transfer belt 8 where the transfer of the black toner image has been completed in the previous image station Pa, and is superimposed on the black toner image.

Hereinafter, image formation is performed in the same manner for the magenta toner image and the yellow toner image, and when the superposition of the four color toner images on the intermediate transfer belt 8 is completed,
Sheet material transfer rollers 12 collectively transfer toner images of four colors onto sheet material 10 fed from sheet cassette 11 by sheet feed roller 9. Then, the transferred toner image is heated and fixed to the sheet material 10 by the fixing device 13, and a full-color image is formed on the sheet material 10.

Each of the photosensitive drums 1a, 1b, 1c and 1d after the transfer is completed is connected to the cleaning means 7a,
At 7b, 7c and 7d, the residual toner is removed, and is prepared for the next image formation to be performed subsequently.

Next, the configuration of the drive unit 2 will be described.

As shown in FIG. 2, the drive unit 2 is provided with a drive motor 14, and a motor pulley 15 a is attached to a motor shaft of the drive motor 14. Further, the drive unit 2 is provided with an intermediate pulley 15b and a final pulley 15c to which a drive spline (drive transmission unit) 17 is integrally attached, and a first-stage timing belt is provided between the motor pulley 15a and the intermediate pulley 15b. A second stage timing belt 16b is stretched over the intermediate pulley 15b and the final pulley 15c.

Thus, the driving force of the driving motor 14 is
The first stage timing belt 16 from the motor pulley 15a
a, intermediate pulley 15b, second-stage timing belt 16
b, transmitted to the drive spline 17 via the final pulley 15c.

Although the present embodiment has a two-stage configuration in which the driving force is transmitted by the two timing belts 16a and 16b, any number of stages may be used as long as the timing belt is used. Is also good.

In the case of a gear, drive unevenness due to eccentricity is likely to occur.
Since the drive unevenness is reduced or eliminated by transmitting the drive force at 6a, 16b, the photosensitive drums 1a, 1b
The angular velocity fluctuations b, 1c, and 1d can be reduced or eliminated, and the displacement of the AC component in the scanning line writing direction can be reduced or eliminated with a low-cost and simple structure.

Next, the drive unit 2 and the photosensitive drum 1
The drive connection with a, 1b, 1c, 1d will be described.

As shown in FIGS. 3 and 4, the drive spline 17 is a driven spline (drive driven portion) mounted on the rotating shaft of the photosensitive drums 1a, 1b, 1c, 1d.
The driving force transmitted to the driving spline 17 is transmitted to the photosensitive drums 1a, 1b, 1c, 1d via the driven spline 18, and thereby the photosensitive drums 1a, 1b, 1c, 1d. Is driven to rotate.

As shown in detail in FIG. 4, the driving spline 17 and the driven spline 18 are formed by inserting the driven spline 18 in the axial direction with respect to the driving spline 17 so that the outer periphery of the driving spline 17 and the inner periphery of the driven spline 18 are formed. The parts are connected by engaging with each other. By using the splines 17 and 18 as described above, the two can be smoothly and smoothly connected.

The splines 17 and 18 are involute in the tooth profile, and the driving spline 17 and the driven spline 18 are easily engaged with each other, so that the driving force of the driving spline 17 can be smoothly and stably transmitted to the driven spline 18. Can be. Thus, the angular velocity fluctuation can be reduced or eliminated, and the displacement of the AC component can be reduced or eliminated.

Further, the drive spline 17 is stepped in the axial direction, and the tip is thinner than the root. Then, as shown in FIG. 5, the peak diameter of the spline teeth at the root coincides with the trough diameter of the spline teeth of the driven spline 18, whereby the driven spline 18 has the spline teeth at the root of the driving spline 17. It is positioned in the radial direction by the peak diameter.

In practice, the diameter of the spline teeth at the root of the driving spline 17 is made larger than the root diameter of the spline teeth of the driven spline 18 so that the driven spline 18 is inserted with a slight press fit due to the problem of machining accuracy.

As described above, according to the present embodiment, the positioning is performed at a part of the splines 17 and 18 in the axial direction, so that the driving spline 17 and the driven spline 18 may be engaged at the time of insertion. Therefore, the driven spline 18 can be smoothly and smoothly inserted into the drive spline 17.

In this case, the root diameter of the spline teeth at the root is made to match the root diameter of the spline teeth of the driven spline 18, but the root diameter of the spline teeth at the root part is set to the root diameter of the spline teeth of the driven spline 18. May be matched.

Further, according to such a configuration, the driven spline 18 is integrated with the drive spline 17, so that the rotation center of the photosensitive drum 1 can be made to coincide with the rotation center of the drive spline 17, and Can be reduced or eliminated, and the displacement of the AC component can be reduced or eliminated.

Here, as shown in FIG. 6, since the driving spline 17 and the driven spline 18 are not positioned, there is a backlash in the radial direction. Further, as shown in FIG. Let us consider a case where the rotation center of the driven spline 18 of the photosensitive drum 1 is shifted upward by E and fixed with respect to the rotation center of.

In FIG. 7, A is the center of the ridge diameter and valley diameter of the drive spline 17 of the drive unit, that is, the pitch circle, and B is the pitch circle of the driven spline 18 of the photosensitive drum 1.

As shown, the pitch circle of the driven spline 18 of the photosensitive drum 1 is decentered by E with respect to the center of rotation. Actually, the pitch circle of the driven spline 18 of the photosensitive drum 1 is also eccentric due to the problem of processing accuracy. However, here, for convenience of explanation, the photosensitive drum 1
It is assumed that only the pitch circle of the driven spline 18 has eccentricity.

FIG. 7A shows a state where the pitch circle of the driven spline 18 of the photosensitive drum 1 is eccentric downward. At this time, the engagement position between the driving spline 17 and the driven spline 18 is on the upper side. And
Assuming that the driving spline 17 is rotating at a constant angular velocity ω0 about its rotation center, the driven spline 18 rotates at ω1. Here, since the distance from the rotation center of the driven spline 18 to the meshing position is short, ω1> ω0, and the driven spline 18, that is, the photosensitive drum 1 rotates at a higher angular velocity than the driving spline 17.

In FIG. 7B, the photosensitive drum 1 is 180
, The pitch circle of the driven spline 18 is eccentric upward. At this time, the engagement position between the driving spline 17 and the driven spline 18 is on the lower side. The driving spline 17 is also rotating at the constant angular speed ω0, while the driven spline 18 is rotating at ω2. Here, since the distance from the rotation center of the driven spline 18 to the engagement position is large, ω2 <ω0, and the driven spline 18, that is, the photosensitive drum 1 is driven spline 17
It will rotate at a lower angular velocity.

From the above, it can be seen that the distance from the rotation center of the driven spline 18 of the photosensitive drum 1 to the meshing position fluctuates in one rotation cycle, and the angular velocity fluctuates accordingly.

Here, since the writing position of the latent image on the photosensitive drum 1 and the transfer position of the toner image to the transfer belt are far apart, for example, when a ladder pattern is formed, the pitch is It changes in one rotation cycle of the drum 1. Specifically, assuming that the latent image writing position is 180 ° apart from the latent image writing position and that the latent image writing is performed when the photosensitive drum 1 is rotating at a high angular velocity, the transfer position Then, photosensitive drum 1
Of the ladder pattern becomes longer, and the pitch of the ladder pattern becomes longer. Conversely, when writing of a latent image is performed while the angular velocity of the photosensitive drum is low, the pitch is reduced. That is, a displacement of the AC component occurs such that the pitch of the ladder pattern expands and contracts in one rotation cycle of the photosensitive drum 1. This also means that jitter and density unevenness in one rotation cycle of the photosensitive drum 1 occur.

In the above description, a case has been considered where the rotation center of the driven spline 18 of the photosensitive drum 1 is fixed to be shifted upward with respect to the rotation center of the driving spline 17 of the drive unit. A similar phenomenon occurs.

On the other hand, as shown in FIG.
When the driven spline 18 is positioned in the radial direction by the driving spline 17 of the driving unit, even if the pitch circle of the driven spline 18 of the photosensitive drum 1 is eccentric, FIGS. As shown, there is no change in the distance from the rotation center of the photosensitive drum 1 to the meshing position, and the rotation center of the driving spline 17 matches the rotation center of the driven spline 18 attached to the photosensitive drum 1. As a result, the rotation angle of the driving spline 17 and the rotation angle of the driven spline 18 coincide with each other, so that the displacement of the AC component in one rotation period of the photosensitive drum as shown in FIG. 7 does not occur.

That is, the images on the plurality of photosensitive drums 1 are transferred to the same position on the intermediate transfer belt 8, and no color shift occurs. Also, when viewed in a single color, no jitter or density unevenness occurs during one rotation cycle of the photosensitive drum.

(Embodiment 2) FIG. 9 is a perspective view showing a drive unit and a photosensitive drum of an image forming apparatus according to Embodiment 2 of the present invention, FIG. 10 is a perspective view showing a main part of FIG.
FIG. 11 is an explanatory diagram showing a meshing state between the driving spline and the driven spline in FIG. Note that the overall configuration of the image forming apparatus according to the present embodiment is the same as that shown in FIG. 1 in the first embodiment, and therefore illustration and description are omitted.

As shown in FIGS. 9 and 10, the driving spline 17 is connected to a driven spline 18 mounted on the rotating shaft of the photosensitive drums 1a, 1b, 1c, 1d. 1a, 1b, 1
c and 1d are driven to rotate.

As shown in detail in FIG. 10, the driving spline 17 and the driven spline 18
Are connected to the drive spline 17 by being inserted in the axial direction. Thereby, both are smoothly and smoothly connected.

As shown in FIG. 11, the splines 17 and 18 have parallel teeth and do not generate a radial acting force due to the rotation torque of the driving spline 17, so that the driven spline 18, that is, the photosensitive It is possible to prevent the rotation center of the body drum 1 from being shifted from the rotation center of the drive spline 17. As a result, as in the case of the first embodiment, the angular velocity fluctuation of the photosensitive drum 1 can be reduced or eliminated, and the displacement of the AC component can be reduced or eliminated.

Further, the drive spline 17 is stepped in the axial direction, and the tip is thinner than the root. Then, as shown in FIG. 11, the peak diameter of the spline teeth at the root portion matches the valley diameter of the spline teeth of the driven spline 18, and the driven spline is
Is positioned in the radial direction by the peak diameter of the spline teeth at the root of the spline. In practice, due to the problem of machining accuracy, the peak diameter of the spline teeth at the root of the driving spline 17 is made larger than the root diameter of the spline teeth of the driven spline 18 so that the driven spline 17 is inserted slightly.

As described above, according to the present embodiment, the positioning is performed at a part of the splines 17 and 18 in the axial direction. Therefore, the driving spline 17 and the driven spline 18 may be engaged at the time of insertion. Therefore, the driven spline 18 can be smoothly and smoothly inserted into the drive spline 17.

Here, the root diameter of the spline teeth at the root part is made to match the root diameter of the spline teeth of the driven spline 18, but the root diameter of the spline teeth at the root part is set to the root diameter of the spline teeth of the driven spline 18. The same effect can be obtained even if it is matched.

Further, with such a configuration, the driven spline 18 is integrated with the driving spline 17, so that the rotation center of the photosensitive drum 1 can be made to coincide with the rotation center of the driving spline 17, and Can be reduced or eliminated, and the displacement of the AC component can be reduced or eliminated.

In the above description, the tandem type multiple image forming apparatus has been described. However, the present invention is not limited to the multiple image forming apparatus in which the transfer member is rotated a plurality of times to superimpose images, or a single-color image forming apparatus. It can also be applied to a forming apparatus. Therefore, in various image forming apparatuses, it is possible to form a high-quality image in which jitter and uneven density and furthermore, a pitch shift when forming a ladder pattern or the like are reduced or eliminated.

[0075]

As described above, according to the present invention, the center of rotation of the drive transmission unit and the center of rotation of the drive follower unit coincide with each other, so that angular velocity fluctuations are reduced or eliminated, and a low-cost and simple structure is achieved. Therefore, an effective effect that it becomes possible to reduce or eliminate the displacement of the transfer position of the AC component is obtained.

When the drive follower is positioned in the radial direction such that the outer peripheral portion of the drive transmission portion and the inner peripheral portion of the drive follower engage with each other, the rotation center of the drive transmission portion and the rotation of the drive follower can be rotated. Since the center and the center can be more accurately matched, the angular velocity fluctuation can be reduced or eliminated, and A
An effective effect that it is possible to reduce or eliminate the transfer position shift of the C component is obtained.

If the root portion of the drive transmitting portion is engaged with the distal end portion of the drive driven portion, the drive transmission portion and the driven driven portion can be smoothly and smoothly engaged with each other. The rotation center of the unit and the rotation center of the driven unit can be accurately matched to reduce or eliminate the angular velocity fluctuation, and the effective effect of reducing or eliminating the transfer position deviation of the AC component can be obtained. can get.

If the valley diameter of the spline teeth on the drive driven portion side is determined in the radial direction by the peak diameter of the spline teeth on the drive transmission portion side, the engagement between the drive transmission portion and the drive driven portion can be smoothly and smoothly performed. In addition, the rotation center of the drive transmission unit and the rotation center of the drive driven unit can be accurately matched to reduce or eliminate the angular velocity fluctuation,
An effective effect of being able to reduce or eliminate the displacement of the transfer position of the AC component is obtained.

By forming the spline teeth into involute teeth, it is possible to smoothly and stably transmit the driving force of the drive transmission unit to the drive follower unit, and to achieve the rotation center of the drive transmission unit and the rotation of the drive follower unit. It is possible to reduce or eliminate the angular velocity fluctuation by accurately matching the center with the center, and to obtain an effective effect that it is possible to reduce or eliminate the transfer displacement of the AC component.

By making the spline teeth parallel, the rotational center is prevented from being shifted due to the rotational torque acting in the radial direction, and the rotational center of the drive transmission unit and the rotational center of the drive follower are prevented from shifting. Is accurately matched to reduce or eliminate the angular velocity fluctuation, and an effective effect that it is possible to reduce or eliminate the transfer displacement of the AC component is obtained.

By using the timing belt for transmitting the driving force, the rotation unevenness of the driving system itself can be reduced or eliminated, and the fluctuation of the angular velocity of the photosensitive member can be reduced or eliminated. An effective effect of being able to eliminate is obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an image forming apparatus according to a first embodiment of the present invention;

FIG. 2 is a perspective view showing a configuration of a drive unit in the image forming apparatus of FIG.

FIG. 3 is a perspective view showing a drive unit and a photosensitive drum of FIG. 2;

FIG. 4 is a perspective view showing a main part of FIG. 3;

FIG. 5 is an explanatory diagram showing a meshing state between a driving spline and a driven spline in FIG. 4;

FIG. 6 is an explanatory diagram showing a radial play in a state where a driving spline and a driven spline are connected to each other.

FIG. 7 is an explanatory diagram showing an angular velocity variation due to a shift of a rotation center between a driving spline and a driven spline.

FIG. 8 is an explanatory diagram illustrating transmission of angular velocity by a driving spline and a driven spline in the image forming apparatus according to the first embodiment;

FIG. 9 is a perspective view showing a drive unit and a photosensitive drum of the image forming apparatus according to Embodiment 2 of the present invention.

FIG. 10 is a perspective view showing a main part of FIG. 9;

FIG. 11 is an explanatory diagram showing a meshing state between a driving spline and a driven spline in FIG. 10;

FIG. 12 is an explanatory diagram showing types of displacement of a transferred image.

FIG. 13 is a perspective view showing a correction mechanism in a conventional image forming apparatus.

FIG. 14 is an explanatory diagram showing types of AC component errors in scanning lines of a conventional image forming apparatus.

[Explanation of symbols]

 1a, 1b, 1c, 1d Photoreceptor drum (photoreceptor) 2 Drive unit 3a Charging means 4 Exposure means 5a Developing means 6a Transfer means 16 Timing belt 17 Drive spline (drive transmission unit) 18 Drive spline (drive follower)

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Kohei Suyama 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. Term (reference) 2H035 CG03 2H071 CA02 DA26 3J103 AA02 AA64 FA15 FA30 GA03 GA52 GA74

Claims (7)

[Claims] A photoconductor, a charging unit configured to uniformly charge the surface of the photoconductor, and irradiating the charged photoconductor with exposure light corresponding to image data to form an electrostatic latent image. Exposure means; developing means for visualizing the electrostatic latent image formed on the photoreceptor; transfer means for transferring a toner image developed on the photoreceptor to a transfer material; And a drive transmission unit to which the driving force is transmitted. The drive transmission unit is mounted on the rotation axis of the photoconductor, is positioned in the radial direction by the drive transmission unit, is connected to the drive transmission unit, and is transmitted from the drive transmission unit. An image forming apparatus comprising: a driving follower that transmits a driving force of the driving motor to the photoconductor and rotates the photoconductor. 2. The drive driven portion is positioned in a radial direction such that an outer peripheral portion of the drive transmitting portion and an inner peripheral portion of the drive driven portion are engaged with each other. 2. The image forming apparatus according to 1. 3. The image according to claim 2, wherein said drive transmission portion and said drive driven portion are engaged at a root portion of said drive transmission portion and a distal end portion of said drive driven portion. Forming equipment. 4. The image forming apparatus according to claim 3, wherein a valley diameter of the spline teeth on the drive driven portion side is positioned in a radial direction by a peak diameter of the spline teeth on the drive transmission portion side. 5. An image forming apparatus according to claim 4, wherein said spline teeth have an involute tooth profile. 6. An image forming apparatus according to claim 4, wherein said spline teeth have a parallel tooth shape. 7. A timing belt according to claim 1, wherein a driving force is transmitted from said drive motor to said photosensitive member via said drive transmission section and said driven section. The image forming apparatus according to claim 1.