JP2915690B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus applicable as a facsimile, a printer or a copying machine, and more particularly to a cleaning roller for removing a toner remaining on a photoreceptor after transferring a toner image carried on the photoreceptor. And an image forming apparatus having the same.

[0002]

2. Description of the Related Art Conventionally, an exposure image is formed on a drum-shaped or belt-shaped photosensitive member using a light output corresponding to a document image or image information, and the exposed image is formed using a developing device. 2. Description of the Related Art An electrophotographic apparatus configured to transfer a toner image to a plain paper or other recording material after forming a toner image is known, and is widely used in printers, copiers, and other image forming apparatuses.

[0003] This type of apparatus generally uses a cleaning blade as a cleaning mechanism for removing residual toner adhering to the photosensitive drum after the toner image is transferred. Not only is it difficult to press uniformly on the blade, but also toner solidification occurs on the press contact surface with the blade while the drum is stopped, and if this is left as it is and restarted, the drum will be damaged. Film phenomenon is likely to occur.

For this reason, a rubbing roller composed of an elastic roller or a sponge roller which rotates at a peripheral speed different from that of the photosensitive drum is conventionally provided upstream of the cleaning blade 51, and the rubbing roller previously moves the photosensitive drum. The toner and paper dust attached to the surface are swept off, and the cleaning blade is configured to scrape off only the remaining toner that could not be swept off by the rubbing roller.

In such an apparatus, in order to enable uniform pressure contact between the rubbing roller and the photosensitive drum, both ends of the rubbing roller are parallel to the drum axis, as shown in, for example, JP-A-61-114269. Attached to one end of an arm member rotatable around a support shaft disposed in the center, and configured to be swingable in a direction away from and adjacent to the drum peripheral surface, and a spring is attached to the other end of the arm or a weight is attached. There is disclosed a technique in which a pressing force is applied to the drum peripheral surface side by mounting.

[0006]

However, in such prior art, the support shaft for rotatably supporting the arm cannot always be made parallel to the drum axis due to an assembly error or the like. A certain amount of play is required for the bearing to be rotatably supported on the bearing, which makes it more difficult to achieve the parallelism. Even if the degree of parallelism can be achieved, it is impossible to follow the eccentricity of the drum peripheral surface if it is eccentric.

Further, a driving system is connected to one shaft end of the sliding contact roller because the sliding contact roller needs to rotate at a peripheral speed different from that of the photosensitive drum. In such a configuration, the driving system is connected. On the other hand, the combined force of the torque reaction force in the tangential direction of the sliding roller due to the rotation of the drive system and the biasing force of the spring acts on the side connected to the drive system, while on the other side of the sliding roller Since only the urging force of the spring acts and the contact pressure becomes non-uniform in the axial direction, smooth cleaning cannot be performed.

[0008] In view of the drawbacks of the prior art, the present invention provides
Even when the peripheral surface of the drum and the peripheral surface of the cleaning roller are eccentric, a smooth line contact is obtained by following the eccentricity, and even when a drive system is attached to one shaft end side of the cleaning roller, it is uniform in the axial direction. It is an object of the present invention to provide an image forming apparatus capable of obtaining a high contact pressure.

[0009]

According to the present invention, as shown in FIG. 1, a pair of bearings 501 and 502 are provided at both ends in the axial direction of the cleaning roller 50. A point provided with a pair of guide portions 521 and 523 (see FIGS. 2A and 2B) that slidably support 501 and 502 only in a direction of contacting and separating from the peripheral surface of the photosensitive drum 1; It is provided with a pair of spring members 54 and 55 for urging elastic force toward the photosensitive drum 1 side, respectively, and is obtained from drive systems 11 to 18 (see FIG. 4) for applying a rotational force to the cleaning roller 50. An image forming apparatus is proposed in which the urging force between the pair of spring members 54 and 55 is made different in accordance with the torque reaction force. The present invention is particularly effective for a device in which the peripheral speed of the cleaning roller 50 is made different from the peripheral speed of the drum and the rotational force is set so as to rub the surface of the photosensitive drum 1, but the present invention is not limited to this. Note that the direction in which the photosensitive drum 1 is separated from and in contact with the peripheral surface is not necessarily limited to the radial direction, but includes a surface parallel to the radial direction.

[0010]

First, the cleaning roller 50 does not swing around the fulcrum as in the prior art, but swings along the direction in which the cleaning roller 50 separates from the circumferential surface of the photosensitive drum 1. Even if there is eccentricity on the surface, it swings following this, and line contact can always be ensured. When a drive system is connected to one shaft end of the cleaning roller 50, the torque connection in the tangential direction of the cleaning roller 50 due to the rotation of the drive system on the connection side of the drive system as shown in FIG. to the sum of the forces F ₃ and the urging force F ₁ of the spring acts on the side connected to the drive system, by increasing or decreasing the urging force F ₁ of the spring in response to the torque reaction force F ₃ , whereas the other side shaft end of the spring is thereby it is possible to balance the biasing force F ₂ of the roller, resulting in the axial direction can be obtained a contact thickness equal to. 5 (A) and 5 (B), the free end of the scraper 57 fixed on the step under the screw roller 53 is brought into contact with the peripheral surface of the cleaning roller 50, as shown in FIGS. There is an apparatus that cleans the surface, but in such an apparatus, as shown in FIG. 5A, when the edge of the scraper is cut into the roller, a large amount of torque is required to drive the roller. In addition, there may be cases where an even contact pressure cannot be obtained due to torque fluctuation or the like. Therefore, the present invention provides FIG.
As shown in (B), the scraper is designed so that the edge of the scraper escapes from the peripheral surface of the roller, more specifically, the angle θ between the scraper and the tangential direction on the downstream side in the roller rotation direction is obtuse. It is good to set the disposition angle of. Thus, the driving torque of the cleaning roller 50 is reduced and the torque is prevented from fluctuating. This is particularly effective for the cleaning roller 50 having a large frictional resistance with bubbles and an elastic roller having a low rubber hardness.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Not just. FIG.
Reference numeral denotes a photosensitive drum unit incorporated in the image forming apparatus according to the embodiment of the present invention. The photosensitive drum 1 including a heater 2 has an opening on the right and lower sides of the photosensitive drum 1 in the drawing so as to face a developing unit and a transfer unit (not shown). In addition, an LED unit 3, a charger 4, an eraser 7, and a cleaning mechanism 5 are arranged from the upper side to the left side of the drum in FIG.

The cleaning mechanism 5 is provided with a cleaning roller 50 and a cleaning blade 51 on the side facing the peripheral surface of the photosensitive drum 1 along the rotation direction thereof, and the peripheral surface and the tip of the blade 51 can be pressed against the drum. And the frame 52 that supports or supports them is substantially
A screw roller 53 that is formed in a letter shape and extends parallel to the drum axis together with the cleaning roller 50 is disposed behind the frame 52. Reference numeral 59 denotes a mylar for preventing detachment of the residual toner from the frame 52. The screw roller 53 and the cleaning roller 50 are connected to a drive system described later, and are configured to be rotatable in the same direction. The peripheral speed of the cleaning roller 50 is set to be higher than the peripheral speed of the photosensitive drum 1, so that the residual toner is scraped off toward the upper side of the cleaning roller 50. The free end of the mylar film-shaped scraper 57 fixed on the step under the screw roller 53 is removed from the peripheral surface of the cleaning roller 50 so that residual toner and foreign matter adhering to the cleaning roller 50 are removed at every rotation. Is in contact with At this time, as shown in FIG. 5B, the angle θ between the scraper 57 and the tangential direction on the downstream side in the rotation direction of the roller 53 becomes obtuse so that the edge of the scraper 57 does not bite into the cleaning roller 50. The scraper 57 is extended by setting the disposition angle as described above, and the disposition angle of the scraper 57 is slightly inclined downward to the screw roller 53 side. As a result, the residual toner removed from the cleaning roller 50 is easily guided to the screw roller 53 side, which is preferable.

FIG. 6 is a plan sectional view showing the relationship between the cleaning mechanism 5 and the photosensitive drum 1, and FIG. 2A is a sectional view taken along line AA of FIG. As is clear from this figure, the cleaning roller 50 on the side connected to the drive system.
And the screw roller 53 are integrally supported by a rectangular bearing portion 501, and the rectangular bearing portion 501 has a frame 521 (hereinafter, referred to as a frame) surrounding the photosensitive drum 1 on three sides except for the side facing the photosensitive drum 1. (Referred to as a guide frame), and is configured to be slidable only in the horizontal direction in which the photosensitive drum 1 is separated from and in contact with the photosensitive drum 1. A spring mounting hole 522 is provided on the back side of the guide frame 521, and the bearing portion 501 is provided in the hole 522.
Is interposed in a coil spring 54 that presses in the direction of approaching the drum.

The cleaning roller 50 on the side opposite to the drive system
2B, only the cleaning roller 50 is pivotally supported as shown in FIG. 2 (B), the screw roller 53 passes through a stupid hole 503 provided in the bearing portion 502, and the shaft end of the screw roller 50 is fixed. It is configured to be connectable to a belt transport mechanism 8 for guiding to the illustrated residual toner collecting container. Then, the rectangular bearing portion 502 is similarly connected to the guide frame 52.
3 and is slidable only in the horizontal direction in which the photosensitive drum 1 is separated from and in contact with the photosensitive drum 1.
A spring interposition hole 524 is provided on the back side of the. And a coil spring 55 for pressing the bearing portion 502 in the drum approaching direction is interposed in the hole 524.

FIG. 4 shows the construction of a drive system connected to the cleaning mechanism 5. Numerals 11 and 12 denote drum gears arranged around the shaft end of the photosensitive drum 1.
Reference numeral 12 indicates that the drum gear 11 on the large diameter side meshes with the drive gear 13 in the main body by mounting the drum unit in the main body. On the other hand, the small-diameter drum gear 12 is connected to the shaft gear 16 of the screw roller 53 via an intermediate gear A14 and an intermediate gear B15, and the intermediate gear B15 is a larger-diameter intermediate gear C17.
Are connected with the intermediate gear C17 and the shaft gear 18 of the cleaning roller 50. (Note that, as shown in FIG. 6, the shaft gear 16 of the screw roller 53 and the shaft gear 18 of the cleaning roller 50 are not on the same plane and do not mesh with each other.)

According to this embodiment, the cleaning roller 50 includes the bearing portions 501 and 502 and the guide frame 52.
1 and 523, the photoconductor drum 1 is swingable in a direction in which the photoconductor drum 1 is separated from and in contact with the peripheral surface of the photoconductor drum 1, more specifically, in a plane parallel to the axis of the photoconductor drum 1. A uniform line contact can be obtained irrespective of the eccentricity of one circumferential surface and the variation of the hardness distribution of the cleaning roller 50.

The cleaning roller 50 receives a rotational force from the intermediate gear C via the shaft gear 18 in the direction of the arrow. At this time, the bearing 501 swings along a plane parallel to the axis of the photosensitive drum 1. Since it is freely fitted to the guide frame 521, F _{3 in the} direction of D (−
F ₃ ). Therefore, the urging force of the coil spring 54 urging the bearing portion 501 is F ₁ ,
If the urging force of the coil spring 55 for biasing the other of the bearing portions 502 opposite to the driving system and the F _2, to make equal the biasing force applied to the bearing portion 501 and 502 F ₂ = F <sub>1
+ (- F 3), F</sub> 1> may be set a biasing force F ₂ of F ₁ and the coil spring 55 of the coil spring 54 so as to maintain the relationship of F _2. Thereby, the contact pressure between the cleaning roller 50 and the photosensitive drum 1 can be maintained uniformly in the axial direction.

[0018]

As described above, according to the present invention, even when the peripheral surface of the drum or the cleaning roller has an eccentricity or a variation in hardness distribution, a smooth line contact can be obtained by following the deviation. Even when a driving system is mounted on one shaft end of the cleaning roller, a uniform contact pressure can be obtained in the axial direction. In particular, even when a scraper for cleaning the cleaning roller is provided in the second aspect of the present invention, the driving torque of the cleaning roller can be smoothly reduced, torque fluctuation can be prevented, and the effect can be further enhanced. And so on.

[Brief description of the drawings]

FIG. 1 is a basic configuration diagram of the present invention.

2A is a cross-sectional view taken along line AA of FIG. 6 showing a cross-sectional configuration of a bearing portion of a cleaning roller on a driving system side, and FIG. 2B is a cross-sectional view of a bearing portion of the cleaning roller on the side opposite to the driving system. FIG. 7 is a sectional view taken along the line BB of FIG. 6 showing the configuration.

FIG. 3 is a cross-sectional configuration diagram of a photosensitive drum unit, and is a cross-sectional view taken along line CC of FIG. 6;

FIG. 4 is a sectional view taken along line DD of FIG. 6, showing a configuration of a drive system connected to the cleaning mechanism.

5A is a diagram showing a problem when a scraper is brought into contact with a peripheral surface of a cleaning roller, and FIG. 5B is an operation diagram showing a solution to the problem.

FIG. 6 is a plan sectional view showing a relationship between a cleaning mechanism and a photosensitive drum.

[Explanation of symbols]

 Reference Signs List 1 photosensitive drum 50 cleaning roller 501, 502 bearing part 521, 523 guide part 54, 55 spring member 11-18 drive system

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 21/10-21/12 B41J 13/00 B41J 15/00-15/24

Claims (2)

(57) [Claims] 1. An image forming apparatus having a cleaning roller for removing a residual toner by rubbing against a photosensitive drum in parallel with a photosensitive drum shaft, the cleaning roller being disposed on both ends in the axial direction of the cleaning roller. A pair of bearing portions, a pair of guide portions that slidably support the respective bearing portions only in a direction in which the respective bearing portions are separated from and brought into contact with the peripheral surface of the photosensitive drum, and an elastic force directed toward the photosensitive drum side for each of the bearing portions. And a pair of biasing spring members, wherein the biasing force between the pair of spring members is made different according to a torque reaction force obtained from a drive system that applies a rotational force to the cleaning roller. Image forming device 2. The image forming apparatus according to claim 1, wherein a scraper in the form of a mylar film is brought into contact with the peripheral surface of the cleaning roller so that an angle between the scraper and a tangential direction on the downstream side in the roller rotation direction is obtuse. Image forming apparatus, wherein an angle at which the scraper is disposed is set in the image forming apparatus.