This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2009-058444 filed on Mar. 11, 2009.
(i) Technical Field
The present invention relates to an image forming apparatus, a cartridge, and a cleaning device.
(ii) Related Art
There is a well-known type of image forming apparatus in which a cleaning member (for example, a rubber blade) removes adhesion substances, such as toner and an external additive, which adhere onto an image bearing body retaining a toner image.
The present invention has been made in view of the above circumstances and provides an image forming apparatus, a cartridge, and a cleaning device, which can prevent a damming member from excessively damming the adhesion substance.
According to an aspect of the invention, there is provided an image forming apparatus including:
an image bearing body on which surface an image is formed and borne;
an image forming section that forms the image on the surface of the image bearing body;
a transfer device that transfers the image formed on the surface of the image bearing body to a transferring body;
a cleaning member that comes into contact with the surface of the image bearing body to scrape an adhesion substance from the surface after the transfer device transfers the image to the transferring body;
a storage tank in which the adhesion substance removed by and moved from the cleaning member is stored;
a damming member that obstructs a region between the cleaning member and the storage tank to temporarily dam the adhesion substance moving from the cleaning member to the storage tank on the cleaning member side, the damming member including plural overlapped members having openings, the plural members including a movable member that is slidable with respect to other member; and
a driving section that drives the movable member to change an overlapping amount between the openings of the plural members.
Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein:
The printer 1 illustrated in
A flow of image forming operation in the printer 1 will briefly be described.
In the printer 1 of
The photoreceptor 10 is an example of the image bearing body of the invention in which an image is formed and borne on the surface thereof. The charging roll 11, the exposure device 12, and the development device 13 correspond to an example of the image forming section of the invention. The process cartridge 1B is an example of the cartridge of the invention.
The cleaning device 20 includes a cleaning member 21. The cleaning member 21 is located on the downstream side of the transfer device 14 in the rotating direction of the arrow A and on the upstream side of the charging roll 11, and a leading end of the cleaning member 21 is into contact with an overall width of the photoreceptor 10 along the rotating axis of the photoreceptor 10, thereby scraping the toner adhering to a portion of the photoreceptor 10 in which the toner image is already transferred and removing from the surface of the photoreceptor 10. The removed toner is recovered in a storage tank 22 of the cleaning device 20. The cleaning member 21 of the cleaning device 20 is made of a rubber plate-like member, and the cleaning member 21 is fixed to a wall 22A of the cleaning device 20.
In the cleaning device 20, an external additive and the like other than the toner are also removed and recovered as an adhesion substance adhering to the photoreceptor 10 by the cleaning member 21. However, because the toner makes up large part of the adhesion substance, the toner removal and recovery will be described below as a representative of the adhesion substance. Although described in detail later, a damming member 23 is provided in the cleaning device 20 of the first exemplary embodiment in order to enhance the performance of the cleaning member 21 to clean the toner remaining on the surface of the photoreceptor 10. The damming member 23 obstructs a region between the cleaning member 21 and the storage tank 22 to temporarily dam the toner going from cleaning member 21 to the storage tank 22 on the side of the cleaning member 21. The dammed toner forms a toner reservoir between the cleaning member 21 and the damming member 23. When the toner is increased in the toner reservoir, the toner overflows to the storage tank 22 due to flection of the damming member 23. However, because sometimes the excessively increased toner in the toner reservoir affects the motion of the photoreceptor, an opening is provided in the damming member in order to discharge the excessive toner.
In the printer 1, a control section 1A controls the whole of various operations. In
Although the printer 1 is a monochrome image dedicated machine, the invention may be applied to a color image machine. In the first exemplary embodiment, the photoreceptor is an example of the image bearing body. Alternatively, the image bearing body of the invention may be an intermediate transfer belt.
As illustrated in
The member 23A is fixed to the inside of the wall 22A of the cleaning device 20. The member 23B is fixed to a shaft, and the member 23B is held by a guide 22B while being movable in a horizontal direction of
The operation in which the control section 1A drives the movable member 23B to slidably move the movable member 23B with respect to the fixed member 23A will be described below.
The shaft SH is fixed to an upper end of the movable member 23B, and the shaft SH is held by a retaining member (not illustrated) so as not to be rotatable but to be slidable in the horizontal direction of
The uppermost part of
Therefore, because the toner is not discharged from the openings 231A and 231B, the toner that is removed and moved by the cleaning member 21 is discharged from below the damming member 23 by the flection of the whole of damming member 23, and the toner is stored in the storage tank 22.
The intermediate part of
Therefore, the toner is discharged from an overlapping P between the openings 231A and 231B. And the toner that is removed and moved by the cleaning member 21 is discharged from below the damming member 23 by the flection of the damming member 23 as well as from the openings 231A and 231B.
The lowermost part of
Therefore, the toner is maximally discharged from the openings 231A and 231B, and the amount of toner discharged from the toner reservoir also reaches a maximum.
The control section 1A illustrated in
When high-density images are continuously formed while the overlapping amount between the openings 231A and 231B remains in the state illustrated in the uppermost part of
Therefore, the control section 1A obtains the same image data supplied to the exposure device 12 and the density of the image expressed by the image data, and based on the image density, indirectly learns the increase or decrease in toner dammed in the toner reservoir by the damming member 23. That is, when the image expressed by the image data has high density, consumption of the toner necessary for the development is increased, the remaining toner (and the external additive and the like) is increased after the image transfer, and the amount of toner removed and recovered by the cleaning device 20 is also increased. Therefore, the toner amount is increased in the toner reservoir. On the other hand, when the image expressed by the image data has low density, the remaining toner (and the external additive and the like) is decreased, and the amount of toner removed and recovered by the cleaning device 20 is also decreased. Therefore, the toner amount is decreased in the toner reservoir.
The control section 1A obtains the image density to learn the increase or decrease in toner, and directs the driving circuit 24 to drive the movable member 23B in order to adjust the overlapping amount between the openings 231A and 231B of the fixed member 23A and movable member 23B, respectively, according to the image density. Therefore, the balance between the amount of toner entering the toner reservoir and the amount of toner discharged from the toner reservoir is adjusted to properly maintain the toner amount in the toner reservoir. As a result, the proper amount of toner is replenished between the cleaning member 21 and the photoreceptor 10, and the toner (and the external additive and the like) on the photoreceptor 10 is appropriately removed by the replenished toner and the cleaning member 21.
The operation in which the control section 1A causes the driving circuit 24 to drive the movable member 23B to properly adjust the toner amount in the toner reservoir based on the image density will be described in detail with reference to
In the following description, in an initial state in which the toner reservoir is not formed, it is assumed that the damming member 23 is in the state illustrated in the uppermost part of
When the control section 1A is in the initial state (the uppermost part of
When the control section 1A learns that the integration value of the image density becomes an integration value corresponding to a proper amount of toner in the toner reservoir after the images are continuously formed, the control section 1A determines that the toner amount is properly accumulated in the toner reservoir. Then, from the next image formation, the control section 1A directs the driving circuit 24 to drive the movable member 23B to properly control the toner amount in the toner reservoir based on the density obtained by the image data.
When the control section 1A learns that the image density obtained based on the image data is lower than predetermined standard density, the control section 1A maintains the state illustrated in the uppermost part of
When the control section 1A learns that the image density obtained based on the image data is higher than the predetermined standard density, the control section 1A determines that the toner amount is properly accumulated in the toner reservoir in the state illustrated in the uppermost part of
Thus, when the control section 1A learns that the density of the formed image exceeds the standard density to tend to increase the toner amount in the toner reservoir, the overlapping amount between the openings 231A and 231B of the fixed member 23A and movable member 23B, respectively, is increased to enlarge an area of the toner moving path from the cleaning member 21 to the storage tank 22, and the amount of toner moved from the toner reservoir to the storage tank 22 is increased to properly maintain the toner amount in the toner reservoir. On the other hand, when the control section 1A learns that the image density is lowered to tend to decrease the toner amount in the toner reservoir, the overlapping amount between the openings 231A and 231B is decreased to properly maintain the toner amount in the toner reservoir. The control section 1A continuously adjusts the overlapping amount between the openings 231A and 231B in a non-step manner according to the image density.
When the control section 1A directs the driving circuit 24 to drive the movable member 23B according to the image density increase and decrease corresponding to the increase and decrease of the toner amount in the toner reservoir, the toner amount in the toner reservoir is properly maintained, and the proper amount of toner is replenished between the photoreceptor 10 and the leading end of the rubber plate-like cleaning member 21 that is in contact with the photoreceptor 10. As a result, the toner (and the external additive and the like) on the photoreceptor 10 does not slip through the leading end of the cleaning member 21, but the toner is securely removed to prevent the increase in rotational load on the photoreceptor 10.
In the first exemplary embodiment, the control section 1A is an example of the increase and decrease learning section of the invention, and particularly is an example of the density type increase and decrease learning section. The control section 1A is also an example of the driving control section. The driving circuit 24 and a motor including the driving shaft 24A are an example of the driving section of the invention.
In the second exemplary embodiment, a damming member 33 of a cleaning device 20A and a mechanism retaining the damming member 33 are different from those of the first exemplary embodiment. Also a method of controlling the toner amount in the toner reservoir is different from that of the first exemplary embodiment. In the following description, the components similar to those of the first exemplary embodiment are omitted, and the cleaning device 20A and the toner amount control that are different from those of the first exemplary embodiment will mainly be described.
As illustrated in
The member 33A is fixed to the inside of the wall 22A of the cleaning device 20A. The member 33B is fixed to a shaft, and retained by a guide 22C while being movable in a horizontal direction of
In the damming member 33, a distortion sensor S1 is adhered on a side opposite to the cleaning member 21. The distortion sensor S1 is distorted itself by the flection (that is, a kind of distortion) of the damming member 33, and outputs a signal according to magnitude of the distortion.
The operation in which the control section 1A drives and slidably moves the movable member 33B with respect to the fixed member 33A will be described below.
The shaft SH1 is fixed to a lower end of the movable member 33B, and a contact portion G4 that is in contact with the oval-shaped member G3 is provided in an end portion of the shaft SH1. The shaft SH1 is retained by a retainer (not illustrated) while being movable in a vertical direction of
That is, when the control section 1A directs the driving circuit 34 to rotate the driving shaft of the motor M to rotate the oval-shaped member G3, the shaft SH1 and the movable member 33B are moved in the vertical direction of
In the state illustrated in the uppermost part of
Therefore, because the toner is not discharged from the openings 331A and 331B in the state illustrated in the uppermost part of
At this point, for example, when images having a certain level of high density are continuously formed in the state illustrated in the uppermost part of
Therefore, the control section 1A directly learns the increase and decrease of the toner dammed by the damming member 33, based on the signal outputted from the distortion sensor S1 adhering to the damming member 33. As described above, the distortion sensor Si supplies the signal according to the magnitude of the distortion of itself. The distortion of the distortion sensor S1 is generated by the flection of the damming member 33, and the flection of the damming member 33 is generated by a pressure of the toner dammed by the damming member 33. Accordingly, the magnitude of the signal outputted from the distortion sensor S1 indicates the magnitude of the toner pressure, and the increase and decrease of the magnitude of the output signal indicates the increase and decrease of the toner amount. The control section 1A provides instructions to the driving circuit 34 according to the magnitude of the signal outputted from the distortion sensor S1, and the control section 1A causes the driving circuit 34 to drive the movable member 33B to adjust the overlapping amount between the openings of the fixed member 33A and movable member 33B. However, the adjustment of the overlapping amount in the second exemplary embodiment differs from the adjustment of the overlapping amount in the first exemplary embodiment, and it is a stepwise adjustment to be described later.
The operation in which the control section 1A directs the driving circuit 34 to drive the movable member 33B based on the signal outputted from the distortion sensor S1 will be described with reference to
In the following description, in the initial state in which the toner reservoir is not formed, it is assumed that the damming member 33 is in the state illustrated in the uppermost part of
In the state illustrated in the uppermost part of
After images are continuously formed and the toner amount becomes proper in the toner reservoir, flection begins to be generated in the damming member 33 to increase the magnitude of the signal outputted from the distortion sensor S1. At this point, the control section 1A learns the increase and decrease of the toner in the toner reservoir based on the output signal, and the control section 1A directs the driving circuit 34 to drive the movable member 33B to properly control the toner amount in the toner reservoir.
The control section 1A determines whether the magnitude of the signal outputted from the distortion sensor S1 exceeds a predetermined threshold. When the magnitude of the signal does not exceed the predetermined threshold, the control section 1A maintains the state illustrated in the uppermost part of
The control section 1A causes the driving circuit 34 to drive the movable member 33B to be located at the position illustrated in the intermediate part of
Thus, when the control section 1A directs the driving circuit 34 to drive the movable member 33B based on the signal outputted from the distortion sensor S1, the toner amount is appropriately increased and decreased to properly maintain the toner amount in the toner reservoir. When the toner amount is properly maintained in the toner reservoir, the toner is properly replenished between the photoreceptor 10 and the leading end of the rubber plate-like cleaning member 21 that is in contact with the photoreceptor 10. Accordingly, the toner (and the external additive and the like) on the photoreceptor 10 is securely removed without slipping through the leading end of the cleaning member 21, and the increase in rotational load on the photoreceptor 10 is avoided.
In the second exemplary embodiment, basically the toner amount is properly maintained in the toner reservoir by the control. However, sometimes the toner amount is not properly maintained by the control when images having higher density are continuously formed. Therefore, in the second exemplary embodiment, the following control is performed in order to deal with such cases.
Even after the control section 1A causes the driving circuit 34 to drive the movable member 33B to be located at the position illustrated in the intermediate part of
The control section 1A causes the driving circuit 34 to drive the movable member 33B to put the openings 231A and 231B in the state illustrated in the lowermost part of
Thus, in the second exemplary embodiment, the state illustrated in the intermediate part of
In the second exemplary embodiment, the control section 1A corresponds to an example of the increase and decrease learning section of the invention, particularly to an example of the distortion sensing type increase and decrease learning section. The control section 1A also corresponds to an example in which the increase and decrease determination section and the driving control section are combined, and the driving circuit 24, the motor M, and the oval-shaped member G3 correspond to an example of the driving section of the invention.
The third exemplary embodiment only differs from the second exemplary embodiment in that a laser displacement meter LM is used instead of the distortion sensor S1 in
The laser displacement meter LM irradiates the damming member 33 with a laser beam, receives a reflected light that is reflected from the damming member 33 by a light receiving element, and outputs a signal in accordance with the magnitude of the received light. Although not illustrated, the light receiving element receives the reflected light at a point where the reflected light reaches when the flection is not generated in the damming member 33. The point where the reflected light reaches is displaced accordingly from the position of the light receiving element as the flection of the damming member 33 (that is, a kind of displacement or distortion) is increased. And the amount of a received light received by the light receiving element is decreased as the flection of the damming member 33 is increased, thereby reducing the magnitude of the signal outputted from the laser displacement meter LM. The use of the laser displacement meter LM correctly detects the distortion of the damming member 33 without affecting the motion of the damming member 33 (that is, without interfering with the motion).
In the third exemplary embodiment, the laser displacement meter LM is used instead of the distortion sensor S1 in
In the third exemplary embodiment, the control section 1A corresponds to an example of the distortion type increase and decrease learning section as well as an example of the increase and decrease determination section of the invention. The laser displacement meter corresponds to an example of the distortion meter of the invention.
Next, a fourth exemplary embodiment of the invention will be described. In the first exemplary embodiment, the control section indirectly learns the increase and decrease of the toner amount in the toner reservoir from the density of the image expressed by the image data. On the other hand, in the fourth exemplary embodiment, the control section indirectly learns the increase and decrease of the toner amount in the toner reservoir from a rotating torque of the rotating photoreceptor 10. Except for the method of learning the increase and decrease of the toner amount, the structure of the fourth exemplary embodiment is similar to that of the first exemplary embodiment.
In the fourth exemplary embodiment, the control section 1A of
The photoreceptor driving circuit 18 rotates the photoreceptor 10 at constant speed in order to stably form images. However, when the toner amount is changed in the toner reservoir, in particular when the toner amount is excessively accumulated in the toner reservoir, the rotational load (that is, rotating torque) on the photoreceptor 10 is changed.
That is, when the toner amount is excessively accumulated in the toner reservoir, the toner in the toner reservoir is aggregated near the cleaning member 21 to become the load on the rotation of the photoreceptor 10, and the aggregated toner damps the rotation of the photoreceptor 10. This means that the excessive toner becomes the load to increase the torque for the rotation of the photoreceptor 10.
To keep the rotation speed of the photoreceptor 10 constant even when the rotating torque is increased, the photoreceptor driving circuit 18 automatically adjusts the driving current. Accordingly the increase in the rotating torque induces the increase in the driving current Idrive of the photoreceptor 10 as illustrated in
The detection of the driving current in the photoreceptor driving circuit 18 corresponds to the detection of the rotating torque of the photoreceptor 10. Because the increase and decrease of the rotating torque are caused by the increase and decrease of the toner amount in the toner reservoir, the control section 1A indirectly learns the increase and decrease of the toner amount in the toner reservoir by detecting the increase and decrease of the driving current. When the control section 1A learns the increase of the toner amount in the toner reservoir from the increase in the driving current Idrive, the control section 1A directs the driving circuit 24 to drive the movable member 23B such that the overlapping amount of the openings of the fixed member 23A and movable member 23B is increased. When the control section 1A learns the decrease of the toner amount in the toner reservoir from the decrease in the driving current Idrive, the control section 1A directs the driving circuit 24 to drive the movable member 23B such that the overlapping amount between the openings of the fixed member 23A and movable member 23B is decreased. In the fourth exemplary embodiment, the overlapping amount is adjusted in the stepwise manner like the second exemplary embodiment.
The toner amount is properly maintained in the toner reservoir when the control section 1A adjusts the overlapping amount between the openings based on the detection result of the driving current Idrive.
In the fourth exemplary embodiment, the control section 1A of
Next, a fifth exemplary embodiment and a sixth exemplary embodiment of the invention will be described. The structures of the fifth and sixth exemplary embodiments are similar to those of the first and second exemplary embodiments except that the sizes of the openings of the members forming the damming member are different from each other.
In the first to fourth exemplary embodiments, the openings of the members constituting the damming member have the same size. Mechanisms that retain a photoreceptor, a cleaning member, or a damming member are frequently provided at both ends of the image forming apparatus typified by a printer, and the amount of toner dammed in the toner reservoir easily becomes excessive in the end portion of the photoreceptor 10 rather than the central portion.
Therefore, in the fifth and sixth exemplary embodiments, the sizes of the openings 231A2 and 331B2 located at ends of the damming member 33 are made larger than other openings 231A1 and 331B1 as illustrated in
In the exemplary embodiments, a printer is cited as an example of the image forming apparatus of the invention. Alternatively, the image forming apparatus of the invention may be a copying machine or a facsimile. In the exemplary embodiments, the damming member includes two members. Alternatively, the damming member may include three and more members.
Finally, examples corresponding to the respective exemplary embodiments will be described.
Before describing examples 1 to 6 that are of a machine running test performed by employing the printer of
As a result of the machine running test performed by the printer of
The machine running test is performed by the printer of
In the printer of
In the printer of
In the printer of
The machine running test is performed by applying the structure of
Instead of the structure of
The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The exemplary embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling other skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.
Number | Date | Country | Kind |
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2009-058444 | Mar 2009 | JP | national |