JP2020086392A - Cleaning device, image forming apparatus, and cleaning method - Google Patents

Abstract

To provide a cleaning device that prevents the occurrence of a cleaning failure and turn-up and chipping of a blade, and has a high cleaning effect.SOLUTION: A cleaning device of the present invention is provided with cleaning members 6, 31, 26 that are in contact with surfaces of forward-rolling rotating bodies 1, 15, 25 to remove toner, and a detection member that detects insertion of a foreign substance between the rotating bodies 1, 15, and 25. When the insertion is detected, the cleaning device outputs a signal for reversing the rotation of the rotating bodies 1, 15, 25.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cleaning device, an image forming device, and a cleaning method.

In image forming apparatuses such as printers, copiers, and facsimiles, foreign matter such as paper dust, dust, and hair is present between the image carrier and a cleaning member such as a cleaning blade that removes transfer residual toner on the image carrier. It may get caught.

For example, the image forming apparatus described in Japanese Patent Application Laid-Open No. 2004-242242 removes foreign matter sandwiched between the cleaning member and the image carrier by reversing the operation of the image carrier.

By the way, when the reverse operation of the image carrier for the purpose of removing foreign matter is performed at every predetermined timing such as at the end of printing, by performing the reverse operation of the image carrier even if the foreign matter is not caught. It may cause harmful effects. For example, the toner lumps accumulated on the edge portion of the cleaning blade are not separated from the edge portion by the reverse rotation operation, and the toner lump cannot be completely removed during the normal rotation operation, which may cause cleaning failure. Further, for example, when the toner having lubricity is separated from the edge portion by the reverse rotation operation and the forward rotation operation is performed, the blade is turned up by cleaning the surface of the image carrier whose lubricity is deteriorated by the initial cleaning again. It may cause chipping.

An object of the present invention is to provide a cleaning device, an image forming apparatus, and a cleaning method that suppress the occurrence of defective cleaning, blade curling, chipping, and the like and have a high cleaning effect.

In order to solve the above-mentioned problems, the cleaning device of the present invention detects a cleaning member that comes into contact with the surface of a rotating body that rotates in the normal direction to remove toner, and pinching between the cleaning member and the rotating body. For detecting the pinching by the detection member, and outputs a signal for reversing the rotating body.

According to the present invention, it is possible to suppress the occurrence of defective cleaning, blade curling or chipping, and enhance the cleaning effect.

FIG. 1 is a diagram showing an example of a schematic configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 3 is a diagram showing an example of a schematic configuration of an image forming apparatus when a secondary transfer unit having a belt configuration is applied. FIG. 3 is a block diagram showing an example of a functional configuration of an image forming apparatus related to a cleaning device. FIG. 6 is a diagram for explaining a first example of a mechanism that is provided in the image forming apparatus and that detects the entrapment of foreign matter between the cleaning member and the image carrier. The figure for demonstrating the logic which detects the entrapment of the foreign material with the mechanism of the 1st example shown by FIG. FIG. 6 is a diagram showing an example of a case where the mechanism of the first example shown in FIG. 4 is applied to detection of entrapment of foreign matter between another cleaning member and another image carrier. FIG. 6 is a diagram showing another example of the case where the mechanism of the first example shown in FIG. 4 is applied to detection of entrapment of foreign matter between another cleaning member and another image carrier. 6 is a flowchart showing an operation procedure of a cleaning device in the image forming apparatus. FIG. 6 is a diagram for explaining a second example of a mechanism that is provided in the image forming apparatus and that detects the entrapment of foreign matter between the cleaning member and the image carrier. FIG. 6 is a diagram for explaining a third example of a mechanism that is provided in the image forming apparatus and that detects the entrapment of foreign matter between the cleaning member and the image carrier. FIG. 8 is a diagram for explaining a fourth example of a mechanism that is provided in the image forming apparatus and that detects the entrapment of foreign matter between the cleaning member and the image carrier. The figure for demonstrating the logic which detects the entrapment of the foreign material with the mechanism of the 4th example shown by FIG. FIG. 6 is a diagram for explaining a first pattern of a drive sequence of an image carrier for removing foreign matter in the image forming apparatus. FIG. 6 is a diagram for explaining a second pattern of the drive sequence of the image carrier for removing foreign matter in the image forming apparatus. FIG. 6 is a diagram showing an example of a schematic configuration of an image forming apparatus according to another embodiment of the present invention. FIG. 6 is a block diagram showing an example of a functional configuration of an image forming apparatus according to another embodiment related to a cleaning apparatus. FIG. 6 is a diagram for explaining a first example of a mechanism that is included in an image forming apparatus according to another embodiment and that detects the entrapment of foreign matter between a cleaning member and an image carrier. FIG. 6 is a diagram for explaining a second example of a mechanism that is included in an image forming apparatus according to another embodiment and that detects the entrapment of foreign matter between a cleaning member and an image carrier.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a diagram illustrating an example of a schematic configuration of an image forming apparatus according to an embodiment. FIG. 1 shows an example in which the image forming apparatus is realized as a printer or a facsimile including an image forming unit and a paper feeding unit. The image forming apparatus is not limited to this, and may be realized as, for example, a multi-function machine that further includes a scanner unit, a document conveyance unit, and the like, and that also functions as a copying machine.

In FIG. 1, reference numeral 1 indicates a photosensitive drum that is an image carrier. The cylindrical photosensitive drum 1 basically rotates in the direction of the arrow (normal rotation operation). The photoconductor drum 1 can also rotate in the direction opposite to the arrow (reverse operation).
A roller-shaped charger 2 as a charging unit is pressed against the surface of the photosensitive drum 1. The charger 2 is driven to rotate by the rotation of the photosensitive drum 1. The surface of the photoconductor drum 1 is uniformly charged by applying a bias of a DC voltage (DC) or a DC voltage (DC) superposed with an AC voltage (AC) from the charger 2 by a high-voltage power supply. To be done. Although the charger 2 has a roller shape here, a charging method such as a wire discharge type is also applicable.

Subsequently, the surface of the photosensitive drum 1 is exposed with image information by the exposure member 3 which is a latent image forming means. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 1. This exposure process is performed by a laser beam scanner using a laser diode, an LED (light emitting diode), or the like.

In FIG. 1, reference numeral 4 indicates a developing device that is a developing unit. The developing device 4 visualizes the electrostatic latent image on the photosensitive drum 1 as a toner image by a predetermined developing bias supplied from a high voltage power source. Toner is stored in the developing device 4.
In FIG. 1, reference numeral 10 indicates a process unit. The process unit 10 is a unit in which the photoconductor drum 1, the charging device 2, and the developing device 4 described above and a photoconductor cleaning unit 7 having a photoconductor cleaning blade 6 therein, which will be described later, are integrated. Four process units 10 are arranged in parallel. At the time of forming a full-color image, the visible images of black, cyan, magenta, and yellow are sequentially transferred in the transport direction of the transfer belt 15 that is in contact with each process unit 10 to form a full-color image. To be done. Although the four process units 10 are provided above the transfer belt 15 here, a part or all of them may be provided below the transfer belt 15. is there.

The photoconductor cleaning unit 7, which is a cleaning device, performs cleaning by scraping off the transfer residual toner on the photoconductor drum 1 by the photoconductor cleaning blade 6 that counter-contacts the photoconductor drum 1. Here, an example in which the photoconductor cleaning unit 7 uses a blade cleaning method is shown, but an electrostatic brush method, an electrostatic roller method, or the like can also be applied. That is, as the cleaning member, a brush, a roller, or the like can be applied in addition to the blade.

The transfer belt 15, which is an image carrier, is stretched around a secondary transfer opposing roller that is a transfer driving roller 21, a cleaning opposing roller 16, a primary transfer roller 5 (5_1 to 4), and a tension roller 20. The transfer belt 15 is rotationally driven by a drive motor via a transfer drive roller 21. The drive sources of the process unit 10 and the transfer drive roller 21 may be independent or common. In FIG. 1, the driving of the black process unit 10 and the transfer driving roller 21 are simultaneously turned on/off.
Therefore, at least the drive source for the black process unit 10 and the transfer driving roller 21 is used in common for downsizing and cost reduction of the main body. Further, as a tensioning mechanism for the transfer belt 15, the tension roller 20 is pressed by springs on both sides of the roller shaft. In addition to the tensioning mechanism of the transfer belt 15, a cleaning counter roller 16 is further provided between the tension roller 20 and the transfer driving roller 21, so that the image forming apparatus can transfer the transfer belt by the transfer belt cleaning unit 32 described later. The cleaning effect of 15 is enhanced. The transfer belt 15 can also be reversed in the same manner as the photosensitive drum 1.

The transfer belt cleaning unit 32 is a cleaning device that performs cleaning by scraping off transfer residual toner on the transfer belt 15 by a cleaning blade 31 that is in counter-contact with the transfer belt 15. Similar to the photoconductor cleaning unit 7 described above, the transfer belt cleaning unit 32 is not limited to the blade cleaning system, and an electrostatic brush system or an electrostatic roller system can be applied.

The transfer residual toner scraped off by the cleaning blade 31 is stored in the intermediate transfer member waste toner storage portion 33 through the toner transport path.
The primary transfer rollers 5 (5_1 to 4) are metal rollers or conductive sponge rollers. The primary transfer rollers 5 (5_1 to 4) are arranged to face the photosensitive drum 1 with the transfer belt 15 in between. The primary transfer rollers 5 (5_1 to 4) transfer a toner image on the photoconductor drum 1 to the transfer belt 15 by applying a predetermined primary transfer bias from a single high-voltage power supply. The primary transfer roller 5 (5_1 to 4) includes a metal roller (aluminum, SUS [stainless steel]), an ion conductive roller (urethane+carbon dispersion, NBR [nitri rubber], hydrin rubber), and an electronic conductive type roller (EPDM). [Ethylene propylene rubber]) and the like are used.

As a material used for the transfer belt 15, PVDF (vinyl fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), TPE (thermoplastic elastomer), carbon black, etc. An endless belt in the form of a resin film is used in which the electroconductive material is dispersed.

The secondary transfer unit (rectangular portion of broken line) facing the transfer driving roller 21 via the transfer belt 15 has a roller structure or a belt structure. FIG. 1 shows a secondary transfer unit having a roller structure.
In the case of a roller structure, the secondary transfer roller 25 as a rotating body is, for example, a sponge (rubber or synthetic resin) roller, an ion conductive roller (urethane+carbon dispersion, NBR, hydrin) or an electronic conductive type roller (EPDM). ) And the like are used. A metal roller may be applied as the secondary transfer roller 25. In FIG. 1, reference numeral 27 indicates a secondary transfer roller cleaning unit which is a cleaning device. The secondary transfer roller cleaning unit 27 performs cleaning to scrape off the toner on the secondary transfer roller 25 that has been transferred from the transfer belt 15 by the cleaning blade 26 that counter-contacts the secondary transfer roller 25. As with the photoconductor cleaning unit 7 and the transfer belt cleaning unit 32 described above, the secondary transfer roller cleaning unit 27 is not limited to the blade cleaning system, and an electrostatic brush system or an electrostatic roller system can be applied.

FIG. 2 shows an example of a schematic configuration of an image forming apparatus when a secondary transfer unit having a belt configuration (rectangular portion of broken line) is applied.
The belt-shaped secondary transfer unit includes a secondary transfer roller 25, a cleaning unit 27 having a cleaning blade 26, a secondary transfer belt 28 as a rotating body, and a tension roller 29.
As shown in FIG. 2, in the case of the belt structure, the secondary transfer belt 28 is stretched by the secondary transfer roller 25 (to which a bias is applied) and the tension roller 29. The secondary transfer belt 28 is rotationally driven by a drive motor via the secondary transfer roller 25. Further, in the case of the belt structure, the above-mentioned secondary transfer roller cleaning unit 27 functions as a secondary transfer belt cleaning unit that performs cleaning by scraping off the toner on the secondary transfer belt 28. The secondary transfer roller 25 and the secondary transfer belt 28 can also be reversed in the same manner as the photoconductor drum 1 and the transfer belt 15. Further, in order to enhance the cleaning effect of the secondary transfer belt 28, the cleaning blade 26 is arranged around the winding portion of the secondary transfer roller 25.

Returning to FIG. 1, the description of the configuration of the image forming apparatus will be continued.
For example, a transfer material (transfer body) such as paper is set in the transfer material cassette 22 or the manual feed port 42. These transfer materials reach the secondary transfer position between the secondary transfer roller 25 and the secondary transfer counter roller 21 at the front end portion of the toner image on the surface of the transfer belt 15 by the sheet feeding/conveying roller 23, the pair of registration rollers 24 and the like. Paper is fed at the right time. By applying a predetermined secondary transfer bias between the secondary transfer roller 25 and the secondary transfer counter roller 21 by a high voltage power source, the toner image on the transfer belt 15 is transferred to the transfer material. In this configuration, the paper feed is in a vertical path. The transfer material is separated from the transfer belt 15 by the curvature of the secondary transfer counter roller 21. The toner image transferred to the transfer material is fixed by the fixing member 40 and then discharged from the discharge port 41.

Next, the operation of the cleaning device in the image forming apparatus having the above configuration will be described. As described with reference to FIGS. 1 and 2, this image forming apparatus includes a photoconductor cleaning unit 7 for cleaning the transfer residual toner on the photoconductor drum 1 and a transfer residual toner on the transfer belt 15. There are three types of cleaning devices: a transfer belt cleaning unit 32 for cleaning to scrape off the toner and a secondary transfer roller cleaning unit 27 for cleaning to scrape off the toner on the secondary transfer roller 25 (or the secondary transfer belt 28). Have.

When these cleaning devices apply the blade cleaning method, the blades and the image carrier such as the photosensitive drum 1, the transfer belt 15, the secondary transfer roller 25 (or the secondary transfer belt 28), It is necessary to consider entrapment of foreign matter such as toner lumps, paper powder, dust, fibers, and hair. As a method of removing such foreign matter, the rotating body to which the toner adheres is reversely operated.

The entrapment of foreign matter can occur when the image carrier as a rotating body is operated. Therefore, the reverse operation of the image carrier must be performed for the purpose of removing foreign matter that may be trapped in the image carrier at every predetermined timing, for example, when the printing process ends. Increase the risk of poor cleaning, turning over and chipping. Therefore, the cleaning device in this image forming apparatus is provided with a mechanism for detecting the entrapment of the foreign matter, and when the entrapment of the foreign matter is detected at a predetermined timing when the entrapment of the foreign matter may occur, the reverse operation of the image carrier is performed. The above will be described in detail below.

FIG. 3 is a block diagram showing an example of the functional configuration of the image forming apparatus related to the cleaning apparatus.
As shown in FIG. 3, this image forming apparatus has a detection unit 110 in the cleaning device, and has an I/O unit 120, a control unit 130, and various drive motors 140 as functions related to the cleaning device.

The detection unit 110 detects a state between the cleaning member and the image carrier. That is, the detection unit 110 changes the state between the photoconductor cleaning blade 6 of the photoconductor cleaning unit 7 and the photoconductor drum 1, which changes due to the entrapment of foreign matter, the cleaning blade 31 of the transfer belt cleaning unit 32, and the transfer belt 15. The state between the cleaning blade 26 of the secondary transfer roller cleaning unit 27 and the secondary transfer roller 25 (or the secondary transfer belt 28) is detected. The detection unit 110 outputs detection data (signal) indicating the state between the cleaning member and the image carrier to the I/O unit 120. Some examples of the mechanism of the detection unit 110, which is a detection member, will be described later.

The I/O unit 120 executes data relay, for example, when data is input to a predetermined port, the data is output from the predetermined port. The detection data output from the detection unit 110 is supplied to the control unit 130 via the I/O unit 120.

The control unit 130 controls each component in the image forming apparatus. That is, the control unit 130 is a module that controls the entire image forming apparatus, and as a part thereof, controls the cleaning apparatus. Specifically, the control unit 130, which is a control member, detects foreign matter trapped between the cleaning member and the image carrier based on the detection data from the detection unit 110, and performs the reverse operation of the image carrier. The control unit 130 has a processor and a memory. The control unit 130 causes each component to perform an operation according to the description of the various programs for print processing, for example, by causing the processor to execute the various programs stored in the memory. Various drive motors 140 related to the cleaning device are included in the components controlled by the control unit 130. Specifically, it includes a drive motor for rotating the photosensitive drum 1, the transfer belt 15, and the secondary transfer roller 25 (or the secondary transfer belt 28) in the forward direction or the reverse direction. The control of the various drive motors 140 by the control unit 130 based on the detection data from the detection unit 110 will also be described later.

Here, a first example of the mechanism of the detection unit 110 will be described. FIG. 4 is a diagram for explaining a first example of the mechanism of the detection unit 110 that detects the entrapment of foreign matter between the photoconductor cleaning blade 6 of the photoconductor cleaning unit 7 and the photoconductor drum 1.
As shown in FIG. 4, the photoconductor cleaning blade 6 is composed of a blade holder 6a and a blade 6b. In the first example, first, the blade 6b is made conductive (conductive blade) by, for example, applying a conductive coating to the blade 6b. Instead of providing the conductive coating, the blade 6b may be made of a conductive material. In addition, in the first example, current or voltage is supplied to the conductive blade 6b. Then, in the first example, by reading the change in the current value or the voltage value on the conductive blade 6b, the entrapment of the foreign matter between the blade 6b and the photosensitive drum 1 is detected. With reference to FIG. 5, a logic for detecting the entrapment of a foreign substance by the mechanism of the first example will be described.

In FIG. 5, (A) shows a state in which no foreign matter is sandwiched between the blade 6b, which is a cleaning member, and the photosensitive drum 1, which is an image carrier. On the other hand, (B) shows a state in which a foreign substance (foreign substance 200) is sandwiched between the blade 6b and the photosensitive drum 1. In the first example, it is utilized that the entrapment of foreign matter becomes an electric resistance, and it becomes difficult for current to flow from the blade 6b side to the photosensitive drum 1 side. That is, the measuring device 111 reads an electrical change in current or voltage when the state (A) is changed to the state (B), and detects the entrapment of foreign matter between the blade 6b and the photosensitive drum 1. “Conductive bias” in FIG. 3 indicates the value of current or voltage measured by the measuring instrument. The “conductive bias” is an example of the detection target of the detection unit 110. For example, when measuring a voltage value, if a value higher than a certain width is measured from a value measured in a stationary state where no foreign matter is caught, it is determined that the foreign matter is caught. That is, when a high voltage value exceeding the threshold value is measured, entrapment of a foreign matter is detected. Further, for example, when measuring a current value, if a low value that is less than a certain width is measured from the value measured in a stationary state where no foreign matter is caught, it is determined that the foreign matter is caught. That is, when a low current value less than the threshold value is measured, entrapment of a foreign matter is detected.

4 and 5, the region between the photoconductor cleaning blade 6 of the photoconductor cleaning unit 7 and the photoconductor drum 1 is illustrated as the target region for detecting the entrapment of foreign matter. Between the cleaning blade 31 of the transfer belt cleaning unit 32 and the transfer belt 15, or between the cleaning blade 26 of the secondary transfer roller cleaning unit 27 and the secondary transfer roller 25 (when the secondary transfer unit has a roller structure. In the case of the belt structure, the secondary transfer belt 28. The same applies to the following).

Specifically, in detecting the entrapment of foreign matter between the cleaning blade 31 of the transfer belt cleaning unit 32 and the transfer belt 15, as shown in FIG. 6, a blade holder 31a and a blade 31b that configure the cleaning blade 31 are used. The blade 31b of the blades is made conductive, and a current or voltage is applied to the conductive blade 31b. Then, by reading the change in the current value or the voltage value, the entrapment of the foreign matter between the blade 31b and the transfer belt 15 is detected.

As shown in FIG. 7, when detecting the entrapment of a foreign substance between the cleaning blade 26 of the secondary transfer roller cleaning unit 27 and the secondary transfer roller 25, a blade holder 26a and a blade 26b which form the cleaning blade 26 are detected. One of the blades 26b is made conductive, and a current or voltage is applied to the conductive blade 26b. Then, the change in the current value or the voltage value is read to detect the entrapment of foreign matter between the blade 26b and the secondary transfer roller 25 (or the secondary transfer belt 28).

Next, the control of the various drive motors 140 by the control unit 130 based on the detection data from the detection unit 110 that detects the entrapment of foreign matter in FIG. 3 will be described.
As described above, the entrapment of the foreign matter between the cleaning member and the image carrier may occur when the image carrier is operated. The control unit 130 removes the foreign matter if the foreign matter is detected by the detection data from the detection unit 110 at a predetermined timing such as the end of the printing process involving the operation of the image carrier. The image carrier is reversely operated. In other words, if the entrapment of the foreign matter is not detected, the control unit 130 does not rotate the image carrier in the reverse direction.
When the image carrier is rotated in the reverse direction, specifically, the control unit 130 controls the various drive motors 140 to rotate the image carrier in the reverse direction. Several patterns are conceivable for the drive sequence of the image carrier including the reversing operation for the purpose of removing foreign matter. The drive sequence of this image carrier will be described later.

Further, the process involving the operation of the image carrier is not limited to the print process, and may include, for example, an initialization process when the image forming apparatus is powered on. As the predetermined timing at which the control unit 130 should determine whether or not to perform the reverse operation of the image carrier, it is possible to detect the entrapment of the foreign matter in all of the cases where these processes are executed, and It is also possible to detect the entrapment of a foreign substance when a specific type of processing is executed.

Further, as described above, the entrapment of foreign matter is caused by the secondary transfer roller cleaning unit 27 and the secondary transfer between the photoconductor cleaning unit 7 and the photoconductor drum 1, the transfer belt cleaning unit 32 and the transfer belt 15, and the secondary transfer roller cleaning unit 27. It can occur with the roller 25. When a foreign substance is caught in any of these, the reverse rotation operation of the image carrier is individually performed. When the drive sources of the units are the same, a clutch mechanism may be provided and the units may be separately provided, or the reverse operation time widths may be different for the entire units and synchronous execution may be started.

FIG. 8 is a flowchart showing an operation procedure of the cleaning device in the image forming apparatus in which the various drive motors 140 are controlled by the control unit 130 of FIG.
When the process (job) involving the operation of the image carrier is started (step S1: Yes), the cleaning device changes the state between the cleaning member and the image carrier, which changes depending on whether or not a foreign object is caught ( The state of foreign matter is detected (step S2). As described above, as the target of step S2, all the processes involving the operation of the image carrier may be set, or only a specific type of process among those processes may be set.

In the cleaning device, the processing (job) ends when the value of the detection data indicating the state (foreign matter state) between the cleaning member and the image carrier is less than or equal to a threshold value at which it can be determined that no foreign matter is trapped. In the case (step S3: No, step S4: Yes), the reverse operation of the image carrier (step S6) is omitted. On the other hand, if the processing (job) ends in a state in which the value of the detection data exceeds a threshold value at which it can be determined that a foreign substance is trapped (step S3: Yes, step S5: Yes), the cleaning device The reverse operation of the carrier is executed (step S6).

As described above, the cleaning device in the image forming apparatus performs the reverse operation when the trapping of the foreign matter is detected, so that defective cleaning, curling or chipping can be prevented, and the cleaning effect can be enhanced. It is also possible to reduce the load on the drive gear that occurs during the subsequent forward rotation operation.

Next, a second example of the mechanism of the detection unit 110 will be described. FIG. 9 is a diagram for explaining a second example of the mechanism of the detection unit 110 that detects the entrapment of foreign matter between the cleaning member and the image carrier. FIG. 9 shows the photoconductor cleaning blade 6 of the photoconductor cleaning unit 7, the blade holders 6 a and 6 c which are the constituent members of the photoconductor cleaning blade 6, and the photoconductor drum 1. Here, the detection of the state between the photoconductor cleaning blade 6 of the photoconductor cleaning unit 7 and the photoconductor drum 1 will be described with reference to FIG. 9. In the second example, the transfer belt cleaning unit 32 will be described. Can also be used to detect the state between the cleaning blade 31 and the transfer belt 15 and the state between the cleaning blade 26 of the secondary transfer roller cleaning unit 27 and the secondary transfer roller 25.

In the second example, the vibration sensor 112 detects the vibration of the blade holder 6a during the normal rotation operation of the photosensitive drum 1. Then, in the second example, by reading the change in the vibration, the entrapment of the foreign matter between the blade 6c and the photosensitive drum 1 is detected. Specifically, if a vibration in which the difference from the steady-state vibration in which the foreign matter is not caught has exceeded a certain width is detected, it is determined that the foreign matter is caught. That is, in the second example, when foreign matter is caught during cleaning, the vibration of the cleaning blade 6 changes, and the foreign matter is detected.
In the example of FIG. 9, the vibration sensor 112 is arranged on the upper surface of the blade holder 6a (the surface not facing the photosensitive drum 1). However, the arrangement mode of the vibration sensor 112 is not limited to this example. As another example, the vibration sensor 112 may be arranged on the lower surface of the blade holder 6a (the surface facing the photoconductor drum 1).

Subsequently, a third example of the mechanism of the detection unit 110 will be described. FIG. 10 is a diagram for explaining a second example of the mechanism of the detection unit 110 that detects the entrapment of foreign matter between the cleaning member and the image carrier. Similar to the second example (FIG. 9) described above, detection of the state between the photoconductor cleaning blade 6 of the photoconductor cleaning unit 7 and the photoconductor drum 1 will be described. In the third example, the transfer belt cleaning unit is also described. It can also be used to detect the state between the cleaning blade 31 of 32 and the transfer belt 15 and the state between the cleaning blade 26 of the secondary transfer roller cleaning unit 27 and the secondary transfer roller 25.

In the third example, the strain gauge 113 is attached to the blade 6c. Then, in the third example, the strain gauge 113 detects the strain of the blade 6c when a foreign object is caught. That is, in the third example, focusing on the fact that the blade 6c is distorted by the entrapped foreign matter, the entrapment of the foreign matter with the photosensitive drum 1 is detected.
In the example of FIG. 10, the strain gauge 113 is arranged on the upper surface of the blade 6c (the surface on the side not facing the photosensitive drum 1). However, the arrangement mode of the strain gauges 113 is not limited to this example. As another example, the strain gauge 113 may be arranged on the lower surface of the blade 6c (the surface facing the photoconductor drum 1).

Subsequently, a fourth example of the mechanism of the detection unit 110 will be described. FIG. 11 is a diagram for explaining a fourth example of the mechanism of the detection unit 110 that detects the entrapment of the foreign matter between the cleaning member and the image carrier. Similar to the second example (FIG. 9) and the third example (FIG. 10) described above, the detection of the state between the photoconductor cleaning blade 6 of the photoconductor cleaning unit 7 and the photoconductor drum 1 will be described. In each of the four examples, the state between the cleaning blade 31 of the transfer belt cleaning unit 32 and the transfer belt 15 is detected, and the state between the cleaning blade 26 of the secondary transfer roller cleaning unit 27 and the secondary transfer roller 25 is detected. It can also be used for detection.

In the fourth example, the capacitance sensor 114 (electrode for sensor) is arranged downstream of the contact portion (nip) between the blade 6c and the photosensitive drum 1 (“capacitance sensor” in FIG. 1). The downstream here is premised on the moving direction of the surface of the photosensitive drum 1 during the normal rotation operation of the photosensitive drum 1. Although FIG. 11 shows an example in which the electrostatic capacity sensor 114 is attached to the blade 6c, the present invention is not limited to this, and the electrostatic capacity sensor 114 is arranged at an arbitrary position downstream of the contact portion. be able to. However, it is preferable that the capacitance sensor 114 is arranged near the contact portion.

With reference to FIG. 12, a logic for detecting the entrapment of a foreign substance by the mechanism of the fourth example will be described.
In FIG. 12, (A) shows a state in which no foreign matter is sandwiched between the blade 6c and the photosensitive drum 1. On the other hand, (B) shows a state in which a foreign substance (foreign substance 200) is sandwiched between the blade 6c and the photosensitive drum 1. Further, in (B), reference numeral 201 denotes the transfer residual toner that has passed through the gap created between the blade 6c and the photosensitive drum 1 due to the foreign matter 200 being sandwiched.

The capacitance sensor 114 can be used as a distance measuring sensor that measures the distance to the target by measuring the capacitance generated between the sensor electrode and the target. When the transfer residual toner 201 passes by the entrapment of the foreign matter 200, the distance between the electrostatic capacity sensor 114 and the surface of the photosensitive drum 1 changes (distance x ₁ →distance x ₂ ). In the fourth example, the change in the distance is read to detect the entrapment of the foreign matter. In other words, the fourth example detects the entrapment of a foreign substance by detecting the transfer residual toner that is estimated to have been scraped off due to the entrapment of the foreign substance.

The mechanism of the detection unit 110 adopts the first example between the blade 6c of the photoconductor cleaning unit 7 and the photoconductor drum 1, and the blade 31c of the transfer belt cleaning unit 32 and the transfer belt 15 are used. It is also possible to mix a plurality of types in the image forming apparatus, such as adopting the second example.
Next, a drive sequence of the image carrier for removing foreign matter will be described.

FIG. 13 is a diagram for explaining the first pattern of the drive sequence of the image carrier for removing foreign matter. In FIG. 13, the vertical axis represents the drive torque of the image carrier, and the horizontal axis represents time. Further, reference numeral 300 indicates a time series change of the drive torque of the image carrier.

The first pattern is a pattern in which only the reverse operation of the image carrier such as the photosensitive drum 1, the transfer belt 15, the secondary transfer roller 25 (or the secondary transfer belt 28) is performed.
In the first pattern, the drive motor accelerates the image carrier in the reverse direction so that the surface of the image carrier moves in the opposite direction by a certain distance, and the image carrier is inertially rotated in the reverse direction (a11). Then, the image carrier that rotates in the reverse direction is decelerated by the brake (a12). In this way, the first pattern causes the image carrier to operate in the reverse direction by the amount required to remove the foreign matter.

FIG. 14 is a diagram for explaining the second pattern of the drive sequence of the image carrier for removing foreign matter. Similar to FIG. 13, in FIG. 14, the vertical axis represents the drive torque of the image carrier and the horizontal axis represents time.
In the second pattern, when the image carrier such as the photoconductor drum 1, the transfer belt 15, the secondary transfer roller 25 (or the secondary transfer belt 28) is reversely operated, the surface of the image carrier is further changed to the image carrier. This is a pattern for performing a normal rotation operation of the image carrier for returning to the position before the reverse rotation operation.

In the second pattern as well, first, the drive motor accelerates the image carrier in the reverse direction so that the surface of the image carrier moves in the reverse direction by a predetermined distance, and the image carrier is reversely operated by inertia (a21). ), and subsequently, the image carrier that is rotating in the reverse direction is decelerated by the brake (a22). In addition to this, in the second pattern, a waiting period is secured so as not to damage the drive motor and the like (a23), and the surface of the image carrier is driven so as to move in the positive direction for a certain distance. The image carrier is accelerated in the forward direction by the motor, and the image carrier is inertially rotated in the normal direction (a24), and subsequently, the image carrier that is normally rotated in the inertial direction is decelerated by the brake (a25). In this way, the second pattern causes the image carrier to rotate in the reverse direction as much as the amount required to remove the foreign matter, and the reverse motion to return the surface of the image carrier to the position before the reverse operation of the image carrier. The image carrier is rotated in the normal direction by the amount.

In this second pattern, the combination of the reverse operation of the image carrier and the normal operation of the image carrier may be repeated a plurality of times. In this case, after the normal rotation operation of the image carrier, a waiting period is secured to prevent damage to the drive motor and the like (a26).

Further, in the second pattern, when the image carrier is rotated in the normal direction, the moving speed of the surface of the image carrier is slowed as compared with the normal operation of the image carrier in a steady state such as a printing process. May be. For example, it is possible to prevent the toner lumps, which are accumulated at the edge portion of the cleaning blade and are separated from the edge portion due to the reverse rotation operation, from colliding with the edge portion of the cleaning blade at high speed. Further, the amount of toner to be removed per unit time is reduced so that this toner lump is surely removed.

Next, another embodiment in which a brush is applied instead of the blade as the cleaning member will be described. FIG. 15 is a diagram showing an example of a schematic configuration of an image forming apparatus according to another embodiment.
As shown in FIG. 15, in this image forming apparatus, the photoconductor cleaning unit 7 for cleaning the transfer residual toner on the photoconductor drum 1 is replaced with the photoconductor cleaning brush 6 instead of the photoconductor cleaning blade 6. 8 is provided. Further, the transfer belt cleaning unit 32, which performs cleaning for scraping off the transfer residual toner on the transfer belt 15, includes a cleaning brush 34 in place of the cleaning blade 31 described above. The secondary transfer roller cleaning unit 27, which performs cleaning to scrape the transfer residual toner on the secondary transfer roller 25 (or the secondary transfer belt 28), includes a cleaning brush 30 instead of the cleaning blade 26.

Even when a brush is applied as the cleaning member, entrapment of foreign matter between the cleaning member and the image carrier may occur. When foreign matter is caught, defective cleaning or the like may occur. Reversing the operation of the image carrier is effective as a method for removing the foreign matter that has been caught even when a brush is used as the cleaning member.

It is preferable to stop the reverse operation of the image carrier to the minimum necessary even when a brush is applied as the cleaning member. Specifically, it is preferable that the reverse rotation operation of the image carrier is executed when the pinch of the foreign matter is detected. Therefore, next, some examples of a mechanism for detecting the entrapment of foreign matter between the cleaning member and the image carrier when a brush is applied as the cleaning member will be described.

FIG. 16 is a block diagram showing an example of the functional configuration of an image forming apparatus according to another embodiment related to the cleaning device.
When the rotating brush is used as the cleaning member, the selection of detection targets by the detection unit 110 is wider than when the blade is used as the cleaning member (see FIG. 3 ). Specifically, when a rotating brush is applied as the cleaning member, the detection unit 110 detects the driving torque of the roller-shaped brush that contacts the surface of the image carrier and rotates in the counter direction with respect to the image carrier. It is possible (“driving torque” in FIG. 16). The “driving torque” is an example of a detection target of the detection unit 110.

FIG. 17 is a diagram for explaining a first example of the mechanism of the detection unit 110 that detects the entrapment of foreign matter between the cleaning member and the image carrier in the image forming apparatus according to another embodiment.
In FIG. 17, the photoconductor cleaning brush 8 of the photoconductor cleaning unit 7 and the photoconductor drum 1 are shown. Here, the detection of the state between the photoconductor cleaning brush 8 of the photoconductor cleaning unit 7 and the photoconductor drum 1 will be described with reference to FIG. 17. In the first example, the transfer belt cleaning unit 32 will be described. Can also be used to detect the state between the cleaning brush 34 and the transfer belt 15 and the state between the cleaning brush 30 of the secondary transfer roller cleaning unit 27 and the secondary transfer roller 25.

In the first example, it is used that the entrapment of foreign matter becomes a physical resistance and the drive torque of the brush 8 becomes dull. That is, the change in the drive torque of the brush 8 (FIG. 17: b1) when the state in the steady state in which the foreign matter is not caught is changed to the state in the abnormal state in which the foreign matter is caught is determined by the motor for rotating the brush. It is read by detecting the torque of the rotary shaft and the torque of the rotary shaft to detect the entrapment of foreign matter between the brush 8 and the photosensitive drum 1. Specifically, when a drive torque that is equal to or less than a threshold value that is lower than the drive torque in a steady state in which foreign matter is not caught is measured, the foreign matter is detected as being caught.

FIG. 18 is a diagram for explaining a second example of the mechanism of the detection unit 110 that detects the entrapment of foreign matter between the cleaning member and the image carrier in the image forming apparatus according to another embodiment. is there. Similar to the second example (FIG. 17) described above, detection of the state between the photoconductor cleaning brush 8 of the photoconductor cleaning unit 7 and the photoconductor drum 1 will be described. It can also be used to detect the state between the transfer belt 15 and the state between the cleaning brush 30 of the secondary transfer roller cleaning unit 27 and the secondary transfer roller 25.

In the second example, current or voltage is applied to the brush 8. That is, the entrapment of the foreign matter is detected by utilizing the fact that the entrapment of the foreign matter becomes an electrical resistance and the current is less likely to flow from the brush 8 side to the photosensitive drum 1 side. Specifically, the change of the current value or the voltage value when the state of the normal state where the foreign matter is not caught occurs to the abnormal state where the foreign matter is caught is read by the measuring instrument 111, and the foreign matter is caught. To detect. For example, in the case of measuring the voltage, if a high value exceeding a certain width is measured from the value measured in a stationary state where no foreign matter is caught, it is determined that the foreign matter is caught. Further, for example, when measuring a current value, if a value lower than a certain width is measured from a value measured in a stationary state where no foreign matter is caught, it is determined that the foreign matter is caught.

Thus, even when a brush is used as the cleaning member, it is possible to detect the entrapment of foreign matter between the brushes 8, 34, 30 and the image carriers 1, 15, 25 (28). Therefore, when the entrapment of the foreign matter is detected, the image carriers 1, 15, 25 (28) are reversed in the driving sequence of FIGS. 13 and 14. That is, by performing the reverse rotation operation when a foreign substance is trapped, it is possible to enhance the cleaning effect and reduce the load of the drive gear generated during the reverse rotation operation.

The cleaning methods such as the photoconductor cleaning unit 7, the transfer belt cleaning unit 32, and the secondary transfer roller cleaning unit 27 do not necessarily have to be unified in the cleaning method in the image forming apparatus. For example, in the photoconductor cleaning unit 7, the photoconductor cleaning blade 6 scrapes off the transfer residual toner on the photoconductor drum 1, and in the transfer belt cleaning unit 32, the cleaning brush 34 removes the transfer residual toner on the transfer belt 15. It may be scraped off. In addition to the mixing of the cleaning methods, a plurality of kinds of mechanisms for detecting the state between the cleaning member and the image carrier may be mixed as described above.

As described above, in the image forming apparatuses according to some of the embodiments shown here, foreign matter may be trapped between the cleaning member and the image carrier, which may be accompanied by the operation of the image carrier, such as a printing process. By performing the reverse operation when a foreign substance is detected to be caught at a predetermined timing such as at the time of completion, it is possible to prevent defective cleaning, curling or chipping.

The above description of some embodiments is not intended to limit the scope of the invention, and various modifications and changes can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1... Photosensitive drum, 6... Photosensitive cleaning blade, 6a... Blade holder, 6b, 6c... Blade, 7... Photosensitive cleaning unit, 8... Photosensitive cleaning brush, 15... Transfer belt, 25... Secondary transfer roller, 26... Cleaning blade, 26a... Blade holder, 26b... Conductive blade, 27... Secondary transfer roller cleaning unit, 28... Secondary transfer belt, 30... Cleaning brush, 31... Cleaning blade, 31a... Blade holder, 31c... Blade , 32... Transfer belt cleaning unit, 34... Cleaning brush, 110... Detecting section, 111... Measuring instrument, 112... Vibration sensor, 113... Strain gauge, 114... Capacitance sensor, 120... I/O unit, 130... Control Part, 140... Various drive motors.

JP, 2007-079126, A

Claims (9)

A cleaning member that removes toner by contacting the surface of a rotating body that rotates in the forward direction;
A detection member for detecting entrapment between the cleaning member and the rotating body,
A cleaning device that outputs a signal for reversing the rotating body when a pinch is detected by the detection member. The cleaning member has conductivity,
The detection member supplies a current or a voltage to the cleaning member, and detects entrapment based on the current value or the voltage value of the cleaning member,
The cleaning device according to claim 1. The cleaning device according to claim 1, wherein the detection member detects pinching based on vibration of the cleaning member during normal rotation of the rotating body. The detection member is an electrostatic discharge generated between the surface of an electrode disposed on the downstream side in the moving direction of the surface of the rotating member from the contact portion between the rotating member and the cleaning member in the normal rotation of the rotating member. The cleaning device according to claim 1, wherein entrapment is detected based on the capacity. The cleaning member is a rotating brush,
The cleaning device according to claim 1, wherein the detection member detects entrapment based on a drive torque of the brush. The cleaning device according to claim 1, wherein after rotating the rotating body, the rotating body is rotated in the normal direction to a position before the reverse rotation. The cleaning device according to claim 6, wherein the reverse rotation of the rotary body and the normal rotation of the rotary body to a position before the reverse rotation are repeated a predetermined number of times. A rotating body,
A transfer member for transferring the toner on the rotating body to a transfer body,
A cleaning device according to any one of claims 1 to 7,
A control member for reversing the rotating body when a signal for reversing the rotating body is received from the cleaning device at a predetermined timing;
An image forming apparatus comprising: A cleaning method for removing the toner of a rotating body rotating in the normal direction by a cleaning member which is brought into contact with the surface of the rotating body,
Detecting entrapment between the cleaning member and the rotating body,
Outputting a signal for reversing the rotating body when pinching is detected,
A cleaning method comprising:

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