JPH0416966A - Photosensitive body driving device - Google Patents

Abstract

PURPOSE:To restrain the unevenness of an image by setting one driving pitch of a driving body directly coupled with a photosensitive body corresponding to the feeding pitch of a photosensitive body which is equal to one scanning pitch in the subscanning direction of an electrostatic latent image. CONSTITUTION:An exposing part 5 for forming the electrostatic latent image is provided on the outer periphery of the photosensitive body 1. Then, one driving pitch of a gear 2 is set corresponding to the feeding pitch of the photosensitive body 1 which is equal to one scanning pitch in the subscanning direction of the electrostatic latent image. In such a case, the rotation of a motor is transmitted to the gear 2 through intermediate gears 3 and 4, one pulse of driving voltage is impressed on the motor, and the photosensitive body 1 is fed by one pitch which is the feeding pitch equal to one scanning pitch in the subscanning direction of the electrostatic latent image when the gear 2 is driven by one pitch. Then, an effect on the feeding quantity of one pitch of the photosensitive body by the unevenness of the rotation of a driving system is made small. Thus, the unevenness of the image is restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a photoreceptor drive device used in image forming apparatuses such as copying machines, facsimiles, and printers that form images based on electrophotography.

Prior Art First, a conventional example described in Japanese Patent Application Laid-Open No. 64-21466 will be described with reference to FIGS. 4 to 7. In the device shown in FIG. 4, a plurality of ribs 21 are arranged radially at one end of a photoreceptor 20, a pin 23 is provided on the outer periphery of a drive shaft 22 that contacts the rib 21, and the rotational force of the drive shaft 22 is transmitted from the pin 23. The photoreceptor 20 is rotated by being transmitted to the rib 21 . In the one shown in FIG. 5, the rotation of the motor is transmitted to a gear 25 directly connected to the photoreceptor 20 via an intermediate gear 24. In the device shown in FIG. 6, tapered serrations 26 and 27 are directly connected to each of the drive shaft 22 and the photoreceptor 20, and the serrations 26 and 27 have play by urging the photoreceptor 20 in the axial direction. This allows them to mesh together without any problems.

Problems to be Solved by the Invention In the device shown in FIG. 4, there is too much play between the rib 21 and the bottle 23, resulting in large uneven rotation of the photoreceptor 20. Further, in the case shown in FIG. 5, uneven rotation occurs in the photoreceptor 20 when there is a load fluctuation due to the influence of backlash in the power transmission path from the plurality of intermediate gears 24 to the gear 25. In the case shown in FIG. 6, when there is a load change, the photoreceptor 2o is displaced in the axial direction, so that play occurs between the serrations 26 and 27.

Furthermore, conventionally, in order to rotate the photoreceptor 20 with a feed amount equal to one scanning pitch in the sub-scanning direction of the static latent image,
The gear 25 and serrations 27 are driven multiple times. As a result, the influence of uneven rotation of the drive system is accumulated multiple times when the photoreceptor 20 is rotated by one scanning pitch.

As a result, if backlash occurs in the rotation transmission path due to changes over time or causes due to the usage environment, etc., and uneven rotation occurs due to load fluctuations, etc., the arrangement pitch of the electrostatic latent image in the sub-scanning direction A noticeable disturbance occurs.

Here, the arrangement of dots in the sub-scanning direction of the electrostatic latent image formed on the photoreceptor 2o by the exposure section and the arrangement of dots after this electrostatic latent image is developed are shown in FIG. The unmarked dots are the electrostatic latent image, and the hatched dots are the developed image. If there is no load fluctuation, Fig. 7 (a
), there is no disturbance in the arrangement pitch of the dots in the sub-scanning direction, but if there is rotational unevenness,
), the arrangement pitch of the dots is extremely disordered, and in areas where there are many overlapping dots, the image is blurred, and in areas where there is space between adjacent dots, the image is skipped.

Means for solving the problem One drive pitch of the drive body directly connected to the photoreceptor,
The pitch was set to correspond to the feeding pitch of the photoreceptor, which is equal to one scanning pitch in the sub-scanning direction of the electrostatic latent image.

When the actuating driver is driven by one pitch, the electrostatic latent image can be moved by one pitch with a feed pitch corresponding to one pitch in the sub-scanning direction. The influence of rotational unevenness can be resolved only once, and therefore, unlike conventional methods, the driver must be driven by multiple pitches in order to advance the photoreceptor one pitch in correspondence with one scanning pitch in the sub-scanning direction of the electrostatic latent image. Compared to the case where the photoconductor is fed by one pitch, the influence of uneven rotation of the driving body on the amount of feed of the photoreceptor per pitch can be reduced, and therefore, unevenness in images can be suppressed.

Embodiment A first embodiment of the present invention will be explained based on FIGS. 1 and 2. 3 is a photoconductor, and a gear 2 which is a driving body is directly connected to the end of this photoconductor 1, and this gear 2 is connected to intermediate gears 3 and 4.
It is connected to a motor (not shown) via a motor. Also,
An exposure section 5 is provided that forms an electrostatic latent image on the outer periphery of the photoreceptor 1 by applying a charge to the outer periphery of the photoreceptor 1 using a charger (not shown) and scanning an optical signal on the charged portion. .

Thus, the pitch of one drive of the gear 2 is set to correspond to the feeding pitch of the photoreceptor l, which is equal to one scanning pitch of the electrostatic latent image in the sub-scanning direction. θ is the angle of one drive pitch of the gear 2, a is the feed pitch of the photoreceptor l equal to one scanning pitch in the sub-scanning direction of the electrostatic latent image formed by the exposure section 5, and radius of the photoreceptor 1. If b is the radius on the pitch circle of gear 2, C is the radius on the pitch circle of gear 2, and d is the driving pitch (l weight in number of teeth) on the pitch circle of gear 2, then d = b
-c/a relationship is established.

In this example, a=10nvn, b=100
μ, (0,1mm), c=50mm, d=o,'
Each is set to 5mm.

In such a configuration, the rotation of the motor is controlled by intermediate gears 3,
4 to gear 2. Here, when one pulse of drive voltage is applied to the motor, gear 2 moves at an angle of θ.
Pitch driven. At this time, the drive pitch d on the pitch circle of gear 2 is 0.5 discs, and the feed pitch a of photoreceptor 1 is 0.1
“It is.

In this way, when the gear 2 is driven by one pitch, the photoreceptor l can be moved by one pitch with a feed pitch corresponding to one scanning pitch in the sub-scanning direction of the electrostatic latent image, and thereby, the photoreceptor l can be moved by one pitch. The influence of rotation unevenness of gear 2 on the feed pitch can be eliminated once, and therefore, unlike conventional methods, the gear 2 needs to be adjusted in order to feed the photoreceptor one pitch corresponding to one scanning pitch in the sub-scanning direction of the electrostatic latent image. Compared to the case where a drive system such as the above is driven for a plurality of pitches, the influence of uneven rotation of the drive system on the amount of feed of the photoreceptor per pitch can be reduced. The situation is shown in Figure 2.

Figure 2 shows the arrangement of dots in the sub-scanning direction of the electrostatic latent image formed on the photoreceptor 20ζ by the exposure section and the arrangement of dots after this electrostatic latent image has been developed. The hatched dots are the electrostatic latent image, and the hatched dots are the image after development.If there is no load fluctuation, the image shown in Figure 2 (
As shown in a), there is no disturbance in the arrangement pitch of the dots in the sub-scanning direction. Even if rotational unevenness occurs, the effect is small for the reasons mentioned above, so that the spacing between dots does not jump or the adjacent dots do not overlap closely as shown in FIG. 2(b). Therefore, image unevenness can be suppressed.

Next, a second embodiment of the present invention will be described based on FIG. In this embodiment, a timing belt 7 is wound around a pair of pulleys 6, one of which is driven by a motor, and the rotation of the timing belt 7 is transmitted to the gear 2. Further, the driving pitch of the gear 2 is set to correspond to the feeding pitch of the photoreceptor 1, which is equal to one scanning pitch of the electrostatic latent image in the sub-scanning direction. Therefore, it is possible to achieve the same objective as in the previous embodiment.

Note that a motor may be directly connected to the photoreceptor 1 as a driving member. In this case, the driving pitch of the motor is set to correspond to the feeding pitch of the photoreceptor 1, which is equal to one scanning pitch of the electrostatic latent image in the sub-scanning direction.

Effects of the Invention As described above, the present invention makes one drive pitch of the driver directly connected to the photoreceptor correspond to a feeding pitch of the photoreceptor that is equal to one scanning pitch in the sub-scanning direction of the electrostatic latent image. By setting this, when the driver is driven by one pitch, the photoreceptor can be advanced by one pitch with a feed pitch corresponding to one pitch in the sub-scanning direction of the electrostatic latent image.
The influence of uneven rotation of the drive body per one feed pitch of the photoreceptor can be eliminated once, and therefore, unlike conventional methods, the photoreceptor is moved one pitch in correspondence with one scanning pitch in the sub-scanning direction of the electrostatic latent image. Compared to the case where the driving body is driven by multiple pitches for feeding, the influence of rotational unevenness of the driving body on the l-pitch feeding amount of the photoreceptor can be reduced, and therefore, image unevenness can be suppressed. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a side view showing a first embodiment of the present invention, FIG. 2 is an explanatory diagram showing the arrangement of dots in an electrostatic latent image and a developed image, and FIG. 3 is a side view showing a second embodiment of the present invention. FIGS. 4 to 6 are side views showing a conventional example, and FIG. 7 is an explanatory view showing the arrangement of dots in an electrostatic latent image and a developed image. ■...Photoreceptor, 2...Driver, 5...Exposure section, b
...Feeding pitch of the photoreceptor, d...Pitch of one drive of the driver

Claims (1)

[Claims] In an image forming apparatus that forms an electrostatic latent image by scanning a rotating photoreceptor with an optical signal from an exposure unit in the main scanning direction and the sub-scanning direction, one drive of a driver directly connected to the photoreceptor A photoconductor driving device, characterized in that the pitch is set to correspond to a feeding pitch of the photoconductor that is equal to one scanning pitch in a sub-scanning direction of an electrostatic latent image.