JPH05289581A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an electrophotographic printer capable of obtaining stable image quality without sticking toner to the light-emitting surface of a lens array, etc., even if the electrophotographic printer is used for a long period. CONSTITUTION:A pair of bearing parts 501 and 502 disposed on both end parts in the axial direction of a cleaning roller 50 removing residual toner, and a pair of guiding parts 521 and 523 supporting respective bearing parts 501 and 502 so as to slide them only in the direction of separating from or coming near the periphery of a photosensitive drum 1, are provided. A pair of spring members 54 and 55 energizing elastic force toward the side of the photosensitive drum 1, are provided on the bearing parts 501 and 502, respectively. Then, a pressing force between a pair of the spring member 54 and 55 is made different from each other in accordance with torque reaction obtained by driving systems 11, 12, and 18 imparting the rotational force of the cleaning roller 50.

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 and a copying machine, and more particularly to a cleaning roller for removing a toner remaining on a photoconductor after transferring a toner image carried on the photoconductor. The present invention relates to an image forming apparatus provided with.

[0002]

2. Description of the Related Art Conventionally, an exposure image is formed on a photosensitive member formed in a drum shape or a belt shape by using light output corresponding to an original image or image information, and the exposure image is formed using a developing device. 2. Description of the Related Art An electrophotographic apparatus in which a toner image can be transferred onto a plain paper or other recording material after being formed into a toner image is well known, and is widely used in printers, copying machines and other image forming apparatuses.

In this type of apparatus, a cleaning blade is generally used as a cleaning mechanism for removing the residual toner adhering to the photosensitive drum after the transfer of the toner image. However, the cleaning blade has an axial direction due to a slight mounting error or the like. Not only is it difficult to press the blades evenly, but toner solidification occurs on the pressing surface with the blade when the drum is stopped, and if this is left as it is and restarted, drum damage occurs, and also the toner The film phenomenon is likely to occur.

For this reason, conventionally, a sliding rubbing roller composed of an elastic roller or a sponge roller rotating at a peripheral speed different from that of the photosensitive drum is arranged upstream of the cleaning blade 51, and the photosensitive drum is previously moved by the sliding rubbing roller. The toner and paper dust adhering to the surface are wiped off, and the cleaning blade is configured to scrape off only the residual toner that cannot be swept off by the rubbing roller.

In order to enable uniform contact between the rubbing roller and the photosensitive drum in such an apparatus, for example, as shown in JP-A-61-114269, both end sides of the rubbing roller are parallel to the drum axis. Is attached to one end side of an arm member rotatable around a support shaft arranged in the center of the arm member so as to be swingable in a direction in which the drum peripheral surface is brought into contact with and separated from the drum peripheral surface. A technique is disclosed in which a pressure contact force is applied to the drum peripheral surface side by mounting the drum.

[0006]

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

Further, since it is necessary to rotate the sliding contact roller at a peripheral speed different from that of the photosensitive drum, a drive system is connected to one shaft end side of the sliding contact roller. In such a structure, the drive system is connected. On the other side, the torque reaction force in the tangential direction of the slide contact roller due to the rotation of the drive system and the combined force of the vector of the urging force of the spring act on the side connecting with the drive system, while on the other side of the slide contact roller. Only the biasing force of the spring acts, and as a result, the contact pressure becomes non-uniform in the axial direction, so that smooth cleaning cannot be performed.

The present invention has been made in view of such drawbacks of the prior art.
Even if the peripheral surface of the drum or the cleaning roller is eccentric, smooth line contact is obtained by following this, and even if a drive system is attached to one shaft end side of the cleaning roller, it is uniform in the axial direction. An object of the present invention is to provide an image forming apparatus capable of obtaining various contact pressures.

[0009]

According to the present invention, as shown in FIG. 1, a pair of bearings 501 and 502 are provided at both ends of the cleaning roller 50 in the axial direction, respectively. A point including a pair of guide portions 521 and 523 (see FIGS. 2A and 2B) that slidably support 501 and 502 only in a direction in which they separate from and contact the peripheral surface of the photosensitive drum 1. It is provided with a pair of spring members 54 and 55 each of which applies an elastic force toward the photoconductor drum 1 side, and it is obtained from drive systems 11 to 18 (see FIG. 4) which applies a rotational force to the cleaning roller 50. An image forming apparatus is proposed which is characterized in that the biasing force between the pair of spring members 54, 55 is made to correspond to the torque reaction force. The present invention is particularly effective for an apparatus in which the peripheral speed of the cleaning roller 50 is 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 peripheral surface of the photoconductor drum 1 separates and contacts is not necessarily limited to the radial direction, but includes a plane parallel to the radial direction and the like.

[0010]

First, since the cleaning roller 50 does not swing around the fulcrum as in the prior art, it swings along the direction in which it separates from and contacts the circumferential surface of the photosensitive drum 1, so that the cleaning roller 50 swings around the photosensitive drum 1. Even if there is eccentricity on the surface, it oscillates following this, and line contact can always be secured. When a drive system is connected to one shaft end side of the cleaning roller 50, the tangential torque reaction of the cleaning roller 50 due to the rotation of the drive system on the drive system connected side is shown in FIG. Since the sum of the force F ₃ and the urging force F ₁ of the spring acts on the side connected to the drive system, the urging force F _{1 of the} spring is increased or decreased in accordance with the torque reaction force F _3. On the other hand, it can be balanced with the urging force F ₂ of the spring on the other shaft end side of the roller, and as a result, a uniform contact thickness in the axial direction can be obtained. In the above apparatus, as shown in FIGS. 5A and 5B, the free end edge of the scraper 57 fixed on the stepped portion below the screw roller 53 is brought into contact with the peripheral surface of the cleaning roller 50 so that the cleaning roller peripheral Although there is a device for cleaning the surface, in such a device, as shown in FIG. 5 (A), when the scraper has a shape in which the edge of the scraper bites into the roller, a large torque is required to drive the roller. In addition to the above, there is a case where a uniform contact pressure cannot be obtained due to torque fluctuation or the like. Therefore, the present invention is shown in FIG.
As shown in (B), the scraper has an end edge that escapes from the roller peripheral surface, and more specifically, an angle θ between the scraper and a tangential direction on the downstream side in the roller rotation direction is an obtuse angle. It is better to set the arrangement angle of. This reduces the drive torque of the cleaning roller 50 and prevents the torque fluctuation, and is particularly effective for the cleaning roller 50 having a large frictional resistance such as bubbles and an elastic roller having a low rubber hardness.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described in detail below as an example with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Not too much. Figure 3
Is a photoconductor drum unit incorporated in the image forming apparatus according to the embodiment of the present invention. The photoconductor drum 1 including the heater 2 is opened on the right side and the bottom side in the figure so as to face a developing unit and a transfer unit (not shown). At the same time, the LED unit 3, the charger 4, the eraser 7, and the cleaning mechanism 5 are arranged from the upper side to the left side of the drum in the figure.

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. In addition, the frame body 52 that supports or supports them is substantially
A screw roller 53, which is formed in a letter shape and extends in parallel with the drum shaft, is arranged on the inner side of the frame 52 together with the cleaning roller 50. Reference numeral 59 is a mylar for preventing the residual toner from being detached from the frame body 52. The screw roller 53 and the cleaning roller 50 are connected to a drive system described later so that they can rotate in the same direction. The peripheral speed of the cleaning roller 50 is set 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. It should be noted that the residual toner or foreign matter attached to the cleaning roller 50 is attached to the free end edge of the scraper 57 in the form of a mylar film fixed on the stepped portion below the screw roller 53 so as to be removed every revolution. Abutting against. At this time, as shown in FIG. 5B, the angle θ formed between the scraper 57 and the tangential direction on the downstream side in the rotation direction of the roller 53 is an obtuse angle so that the edge of the scraper 57 does not bite into the cleaning roller 50. The scraper 57 is extended by setting the disposing angle as described above, and the scraper 57 is disposed so that the disposing angle of the scraper 57 is slightly inclined toward 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 the line AA showing the structure of the bearing portion thereof. 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 is a frame body 521 (hereinafter referred to as a frame body 521 that surrounds the three sides except the side facing the photosensitive drum 1 in a rectangular shape). It is fitted and held in a guide frame) and slidable only in the horizontal direction in which it separates from and contacts the photosensitive drum 1. A spring insertion hole 522 is provided on the back side of the guide frame 521, and the bearing portion 501 is provided in the hole 522.
A coil spring 54 for pressing in the drum approaching direction is interposed.

Cleaning roller 50 on the opposite side of the drive system
2B, only the cleaning roller 50 is rotatably supported, and the screw roller 53 penetrates the inside of the fool hole 503 provided in the bearing 502, so that the shaft end of the screw roller 50 is not supported. It is configured so that it can be connected to a belt transport mechanism 8 for guiding to the illustrated residual toner recovery container. Then, the rectangular bearing portion 502 is similarly formed by the guide frame 52.
The guide frame 523 is configured to be slidable only in the horizontal direction in which it is fitted and held by the photoconductor 3, and is brought into contact with and separated from the photosensitive drum 1.
A spring insertion hole 524 is provided on the back side of the coil spring 55, and a coil spring 55 for pressing the bearing 502 in the drum approaching direction is inserted in the hole 524.

FIG. 4 shows the structure of a drive system connected to the cleaning mechanism 5. Reference numerals 11 and 12 denote drum gears provided on the shaft end side of the photosensitive drum 1 so as to form a ring.
By mounting the drum unit in the main body 12, the drum gear 11 on the large diameter side meshes with the drive gear 13 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 the intermediate gear A14 and the intermediate gear B15, and the intermediate gear B15 is a larger-diameter intermediate gear C17.
Are connected to each other and mesh with the intermediate gear C17 and the shaft gear 18 of the cleaning roller 50. (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.
Since it is configured to be swingable in the direction in which it is separated from and in contact with the peripheral surface of the photosensitive drum 1 via 1, 523, more specifically, in a plane parallel to the axis of the photosensitive drum 1, Uniform line contact can be obtained irrespective of the eccentricity of the 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 in the direction of the arrow via the shaft gear 18, and at this time, the bearing portion 501 swings along a plane parallel to the axis of the photosensitive drum 1. Since it is freely fitted to the guide frame 521, it is F _{3 in the} direction D (in the direction approaching the drum 1, −
The torque reaction force F ₃ ) will be received. Therefore, the urging force of the coil spring 54 urging the bearing 501 is F ₁ ,
When the biasing force of the coil spring 55 that biases the other bearing portion 502 on the opposite side of the drive system is F ₂ , in order to make the biasing forces applied to the bearing portions 501 and 502 equal, F ₂ = F ₁
The biasing forces of F ₁ of the coil spring 54 and F ₂ of the coil spring 55 may be set so as to maintain the relationship of + (− F ₃ ), F ₁ > F ₂ . As a result, the contact pressure between the cleaning roller 50 and the photosensitive drum 1 can be maintained uniform in the axial direction.

[0018]

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

[Brief description of drawings]

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

2A is a sectional view taken along the line AA of FIG. 6 showing a sectional structure of the bearing portion of the cleaning roller on the drive system side, and FIG. 2B is a sectional view of the bearing portion of the cleaning roller on the side opposite to the drive system. It is a BB sectional view taken on the line of FIG. 6 which shows a structure.

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

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

FIG. 5A is a view showing a problem when a scraper is brought into contact with the peripheral surface of the cleaning roller, and FIG.

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

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor drum 50 Cleaning roller 501,502 Bearing part 521,523 Guide part 54,55 Spring member 11-18 Drive system

Claims (2)

[Claims] 1. An image forming apparatus comprising a cleaning roller for removing residual toner by rubbing against the drum in parallel with the shaft of the photosensitive drum. The cleaning roller is disposed at both axial ends 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 they are in contact with the peripheral surface of the photosensitive drum, and an elastic force toward the photosensitive drum side to each of the bearing portions. A pair of spring members for urging, wherein the urging force between the pair of spring members is made to correspond to a torque reaction force obtained from a drive system for applying a rotational force to the cleaning roller. Image forming device 2. The image forming apparatus according to claim 1, wherein a mylar film-shaped scraper is in contact with the peripheral surface of the cleaning roller so that an angle formed between the scraper and a tangential direction on the downstream side in the roller rotation direction is an obtuse angle. An image forming apparatus characterized in that the scraper arrangement angle is set in the