JPH0731433B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a copying machine using an electrophotographic method or an electrostatic recording method,
The present invention can be applied to a recording device and other image forming devices.

(Prior Art) Conventionally, in a recording apparatus using an electrophotographic method of this type of apparatus, a cleaner blade is used in a cleaning device in order to remove toner remaining on a photosensitive drum after a toner image is transferred onto a transfer material. It is pressed against the drum surface. If the positional relationship between the cleaner blade and the photosensitive drum in the drum axial direction is fixed, the photosensitive drum is always rubbed at the same position with the blade. For this reason, there is a problem that the damage of the blade and the influence of fine foreign matter entering between the blade and the photosensitive drum are concentrated on the same portion of the photosensitive drum, and the deterioration of the drum is accelerated due to the damage of the photosensitive drum. .

Further, as a measure against the above, a means for avoiding the same spot rubbing of the photosensitive drum, which is conventionally performed, is, for example, a cleaning blade of a cleaning device used for forming an image on the photosensitive drum or a transfer material from the photosensitive drum. In some cases, a separation claw for separation is moved in the rotation axis direction of this drum.

(Problems to be Solved by the Invention) However, these conventional mechanisms have a complicated structure because they require a separate drive mechanism independent of the drive mechanism of the photosensitive drum. An object of the present invention is to solve the above problems with a configuration that can be achieved simply and at low cost.

(Means for Solving the Problems) The present invention for solving the above problems is an image forming apparatus for forming an image on a transfer material, and is supported by a drum shaft and the drum shaft so as to be movable in the axial direction thereof. A photosensitive drum that rotates by the rotation of the drum shaft; a conversion unit that decelerates the rotation of the drum shaft to convert it into a reciprocating oscillating motion; and a first reciprocating oscillating motion through a first one-way clutch. A transmission means for transmitting the swinging movement in the direction to the first gear as a rotational force, and a second gear meshing with the first gear rotating in the rotation direction transmitted by the transmission means via the second one-way clutch. And a reciprocating means for reciprocating the photosensitive drum in the axial direction by the rotation of the second gear, and the photosensitive drum is moved in the axial direction by the rotation of the drum shaft. An image forming apparatus characterized by being configured to perform a backward movement.

Hereinafter, the present invention will be described in detail with reference to the drawings.

In the embodiments described below, a rotating cylindrical image carrier, a speed reduction mechanism that obtains a reduction ratio from the rotational movement of the image carrier, and the image carrier by the motion obtained by the speed reduction mechanism. The image forming apparatus includes a driving unit that reciprocates in the axial direction and a process unit that is used for forming an image on the image carrier, and reciprocates the image carrier in the rotation axis direction.
Here, as the image bearing member, there is an electrophotographic photosensitive member, a drum such as an insulating drum that holds a latent image or a toner image. Further, as the process means, there are a latent image forming means, a developing device, a cleaning device, and a separating means for separating the transfer material from the image carrier, but it is not essential to have all of these means in the present invention.

FIG. 1 is a sectional view of a photosensitive drum showing an embodiment of an image carrier driving device to which the present invention is applied. In the figure, a bearing 3 is provided at the center of the drum front flange 2 of the photosensitive drum 1.
Has been press-fitted. Reference numeral 5 denotes a centering pin of the photosensitive drum, and the pin and the bearing 3 are fitted so as to be movable in the axial direction. The pin 5 is integrated with the centering plate 4 and fixed to the front plate 7 of the copying machine 4. A compression spring 6 is incorporated between the bearing 3 and the centering plate 4, and the photosensitive drum 1, the drum rear flange 8 and the drum front flange 2 are incorporated.
Is always biased in the direction of arrow D. The operating gear 9 of the photosensitive drum 1 is fixed to the shaft 10. On the other hand, eccentric cam
Numeral 19 is fixed to the rear side plate 11, and the cam lever 13 is constantly urged in the direction of arrow B by the tension spring 20 shown in FIG. 2 to come into contact with the outer peripheral portion of the eccentric cam 19. A gear shaft 15 is provided on the drum side of the lever 13, and a one-way clutch is press-fitted and attached to the cam lever 13 side at a fitting portion with the cam lever 13. The rotation restriction direction of the one-way clutch is the gear shaft 15
Is fixed and the cam lever 13 is rotated in the direction of arrow A, the rotation of the cam lever 13 is restricted.

The cam lever base 14 is fixed to the shaft 10 and supports both the cam lever 13 and the gear shaft 15. A one-way clutch is also press-fitted to the cam lever base 14 side in the fitting portion between the cam lever base 14 and the gear shaft 15. The direction of rotation restriction of the gear shaft 15 relative to the cam lever base 14 is
It is in the same direction as in case 13. Therefore, in FIG. 3, the gear shaft 15 rotates in the arrow C direction when the cam lever 13 rotates in the arrow A direction.

Next, the idler gear 16 will be described. The gear 16 has a cam surface 16 'on the corresponding peripheral surface. The drum rear flange 8 is formed integrally with a driven plate 17 that contacts the cam surface 16 'of the idler gear 16. When the driven plate 17 becomes the cam surface 16 'of the idler gear 16, the photosensitive drum 1 moves in the direction of arrow E in FIG.
The movement of the photosensitive drum 1 in the direction of the arrow D is performed by the compression spring 6
Driven by. A parallel pin 18 is press-fitted into the drum rear flange 8 and slides axially in the sliding portion of the shaft 10. Therefore, it is possible to transmit the rotational movement of the shaft 10 to the photosensitive drum 1 while reciprocating the drum rear flange 8 in the axial direction.

In the drawing, I indicates an image forming area in the width direction of the photosensitive drum. In this embodiment, a part of the mechanism is this area I.
It can be said that it is a progressive structure by improving the inferior space effect due to the presence of overlapping inside, but it is not an essential requirement.

Next, the configuration operation will be described.

In FIG. 3, when the operating gear 9 is rotated clockwise (arrow F), the lever base 1 integrated with the drum shaft 10 is shown.
4, the cam lever 13 and the gear shaft 15 rotate in the directions of the arrows. That is, the cam lever 13 causes the tension spring 20 to move the arrow B
Is always urged in the direction of. This cam lever 13 follows the cam 19 which is mounted eccentrically with respect to the center of rotation of the shaft 10, so that the shaft 13 is rotated by an angle corresponding to the amount of eccentricity.
Shake around a. Then, as described above, the cam lever 13
Since the one-way clutch is press-fitted into the fitting portion of the lever base 14 and the gear shaft 15 with the same locking direction, the gear shaft 15 rotates only in the direction of arrow C.

Next, the reduction ratio by the eccentric cam 19 and the cam lever 13 will be described.

As shown in Fig. 4, the dimensions of each part are set to 2a, b, c, l, x. That is, the amount of eccentricity of the eccentric cam from the center O of the rotating body is x (7th
Fig.), And the rotation angle is θ '(Fig. 6). Cam lever
13 is most vibrated when passing the cam surface of the eccentric cam 19 that is farthest from the rotation center O. The angle at that time is αma
Let x. On the contrary, the eccentric cam 19 closest to the rotation center O
The smallest deflection angle is obtained when passing through the upper cam surface, and the angle at that time is defined as αmin.

Since the respective equations (1) and (2) are established, the cam lever 13 swings by αmax−αmin (= θ) − (3) when the eccentric cam 19 rotates.

Therefore, the reduction ratio m ₁ by the eccentric cam 19 and the cam lever 13 is m ₁ = θ / π- (4).

Further, if the number of teeth of the pinion of the gear shaft 15 and the number of gear teeth of the cam shaft gear 16 are Zp and Zg, respectively, the gear shaft 15 and the cam shaft gear 1
The reduction ratio m ₂ due to 6 is m ₂ = Zp / Zg- (5).

Therefore, the rotation speed of Shaft 10 is It is decelerated with the reduction ratio of.

The cam surface 16 'of the cam-equipped gear 16 is formed in a sinusoidal curve as shown in FIG. The range of the cam surface 16 '(a) is driven plate 17
When the pin portion 17a comes into contact with the driven plate 17, the drum rear flange 8 and the photosensitive drum 1 move in the direction of arrow E in FIG. Since the pin 17a of the drive plate 17 is located at two positions facing each other at the rotation angle of 180 °, the final reduction ratio m is m = 2m ₁ m _2- (7).

Driving in the direction of arrow E in FIG. 3 is performed by transmitting the rotational torque of the shaft 10 to the cam lever 13, the gear shaft 15, the gear 16 with cam and the drive plate 17. On the other hand, as described above, the driving in the direction of the arrow D in FIG. 3 is achieved by the restoring force of the compression spring 6.

The latent image forming process on the photosensitive drum is performed by using a conventional corona charger and irradiation of information light, development is performed by toner, and residual toner is removed by a rubbing means such as a blade in a cleaning device. Therefore, the illustrated description of each of the conventional means is omitted.

(Other Embodiments) In the embodiment of the present invention, as shown in FIG.
The drive in the arrow D direction is performed by the compression spring 6, and the drive in the arrow E direction is realized by the cam surface 16 ′ of the gear with cam 16 pushing the driven plate 17. However, the driving in the direction of the arrow D can also be realized by using a member having the same function as the cam surface 16 'and the driven plate 17 without using the compression spring 6.

Further, as shown in FIG. 2, in the above embodiment, the cam lever
The tension spring 13 is biased in the direction of arrow B by the tension spring 20 and abuts against the eccentric cam 19. However, if the cam surface of the eccentric cam 19 is formed into an eccentric groove shape and the hook 13 'of the cam lever 13 swings following the cam groove, the tension spring 20
Becomes useless.

As described above, according to this embodiment, it is possible to prevent fatigue and deterioration of the same portion of the image bearing member, and it is possible to always maintain stable performance by improving durability. That is,
By having the mechanism in which the image carrier itself reciprocates in the rotation axis direction, the same portion of the image carrier can be continuously used for image formation, and deterioration or damage of the sensitivity characteristics of the photoconductor can be prevented.
In particular, as in the present invention, by incorporating the reciprocating rotation mechanism in the rotation axis direction in the image carrier itself, it is not necessary to provide a drive mechanism different from the drive of the image carrier, so that it is possible to save space in the entire apparatus. To do. Further, as in the embodiment, by constructing a part of this mechanism so as to overlap a part of the image forming area on the peripheral surface of the image carrier, the space saving effect is improved.

(Effects of the Invention) As described in detail above, according to the present invention, the rotational force of the drum shaft can be reduced and then converted into the reciprocating movement force. Therefore, according to the present invention, since the photosensitive drum can be reciprocated by the rotational force of the drum shaft, the drive mechanism for reciprocating the photosensitive drum can be downsized by effectively utilizing the driving force.

[Brief description of drawings]

1 is an axial cross-sectional view of a rotary body drive device, FIG. 2 is a front view of a speed reducer portion with an eccentric cam, FIG. 3 is a perspective view of the rotary body drive device, and FIG. 4 is a size reduction mechanism with an eccentric cam. Explanatory drawing, FIG. 5 is an explanatory view showing the rotation angle and eccentricity of the cam-equipped gear 16, FIG. 6 is a front view of the cam-equipped gear, and FIG. 7 is a side view of the cam-equipped gear. In the figure, 1 ... Photosensitive drum, 2 ... Drum front flange, 4 ... Centering plate, 6 ... Compression spring, 8 ... Drum rear flange, 9 ... Photosensitive drum operating gear, 10 ... Shaft, 13 ...... Cam lever, 13 '... Hook, 14 ... Lever base, 15 ... Gear shaft, 16 ... Gear with cam, 16' ... Cam surface, 17 ... Following plate, 19 ... Eccentric cam.

Claims (1)

[Claims] 1. An image forming apparatus for forming an image on a transfer material, comprising: a drum shaft, a photosensitive drum movably supported by the drum shaft in an axial direction thereof, and rotating by rotation of the drum shaft, A conversion means for decelerating the rotation of the drum shaft to convert it into a reciprocating oscillating motion, and a unidirectional oscillating motion of the reciprocating oscillating motion as a rotational force to the first gear through the first one-way clutch. Transmitting means for transmitting, a second gear meshing with the first gear rotating in the rotation direction transmitted by the transmitting means via a second one-way clutch, and rotation of the second gear Reciprocating means for reciprocating the photosensitive drum in its axial direction, and reciprocating the photosensitive drum in its axial direction by rotation of the drum shaft. Image forming apparatus.