JP2020086012A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can execute reverse movement control for an image carrier at an appropriate timing and prevent the occurrence of turn-up and chipping of a cleaning member or a cleaning failure.SOLUTION: An image forming apparatus comprises: an image carrier 15 that carries a toner image; transfer means that transfers the toner image on a surface of the image carrier 15 to a recording medium; cleaning means 32 that has a cleaning member 31 in contact with the surface of the image carrier; and control means 150 that executes reverse movement control for moving the surface of the image carrier 15 in a direction opposite to that during image formation, and comprises detection means 51 that detects the amount of a foreign substance Pd at a predetermined position 52 in the apparatus. The control means 150 executes the reverse movement control based on a result of the detection performed by the detection means 51.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image forming apparatus.

Conventionally, an image carrier that carries a toner image, a transfer unit that transfers the toner image on the surface of the image carrier to a recording medium, a cleaning unit that has a cleaning member that contacts the surface of the image carrier, and an image carrier An image forming apparatus is known that includes a control unit that executes reverse movement control for moving the surface of the sheet in the direction opposite to that in the image formation.

For example, Patent Document 1 describes an image forming apparatus that changes the frequency of performing the reverse movement control depending on the surface roughness of a recording medium (transfer material) that forms an image.

In the image forming apparatus described in Patent Document 1, the cleaning member may be turned over or chipped, or the toner may pass through the contact portion between the image bearing member and the cleaning member to cause cleaning failure such as scumming on the recording medium. It was likely to occur.

In order to solve the above-mentioned problems, the present invention provides an image carrier for carrying a toner image, a transfer means for transferring a toner image on the surface of the image carrier to a recording medium, and a surface of the image carrier. In an image forming apparatus including a cleaning unit having a cleaning member in contact with the image carrier, and a control unit performing reverse movement control for moving the surface of the image bearing member in a direction opposite to that at the time of image formation, at a predetermined position in the apparatus. It is characterized in that it comprises a detection means for detecting the amount of foreign matter, and the control means executes the reverse movement control based on a detection result of the detection means.

According to the present invention, there is an excellent effect that the reverse movement control of the image carrier can be executed at an appropriate timing to prevent the cleaning member from being turned over or chipped, or the cleaning failure.

FIG. 6 is an explanatory diagram of a configuration for performing reverse rotation control of the intermediate transfer belt based on the amount of paper dust collected from the pair of registration rollers. 1 is a schematic configuration diagram of a printer of an embodiment. FIG. 3 is a schematic configuration diagram of a printer including a secondary transfer belt as a secondary transfer member. The block diagram which shows the outline of the structure which performs reverse rotation control based on the result of the detection means, such as a weight sensor and an optical sensor. The flowchart of control which determines whether reverse rotation control is performed. Timing chart of reverse rotation control.

An embodiment of an electrophotographic image forming apparatus to which the present invention is applied will be described below.
FIG. 2 is a schematic configuration diagram of the printer 100 that is the image forming apparatus according to the embodiment.

As shown in FIG. 2, the four process units 10 having the photoconductor 1, the intermediate transfer belt 15, the secondary transfer roller 25, and the fixing device 40 are provided.
Since the four process units 10 have the same configuration except that the colors of the toners used are different, the reference numerals of the respective members of the process unit 10 are given only to the leftmost one in FIG. There is.
The process unit 10 is configured to integrally support the photoconductor 1, the charging device, the developing device 4, and the photoconductor cleaning device 7. Inside the photoconductor cleaning device 7, a photoconductor cleaning blade 6 as a cleaning member that contacts the surface of the photoconductor 1 is arranged.

The photoconductor 1 is a cylindrical photoconductor drum, and rotates in the clockwise direction in FIG. 2 (the direction indicated by the arrow in FIG. 2) during image formation. A roller-shaped charging roller 2 provided in a charging device serving as a charging unit is pressed against the surface of the photoconductor 1, and the charging roller 2 is driven to rotate by the rotation of the photoconductor 1. The surface of the photoconductor 1 is uniformly charged by applying a bias (DC bias) or a bias obtained by superimposing AC (AC bias) on DC to the charging roller 2 by a high-voltage power supply. In the charging device of this embodiment, the charging method using the charging roller 2 is used, but a charging method using wire discharge may be used.

The photoreceptor 1 whose surface is uniformly charged is exposed based on image information by the exposure light 3 emitted from the exposure device 30 which is a latent image forming means, and an electrostatic latent image is formed. This exposure process is performed by a laser beam scanner using a laser diode or an LED.

A developing device 4 which is a developing unit is arranged on the downstream side in the surface moving direction of the photoconductor 1 with respect to the position where the exposure light 3 of the photoconductor 1 is irradiated. The developing device 4 has an accommodating portion for accommodating a developer containing toner, and a developing roller which is a developer carrying member carrying the developer. Then, by supplying a predetermined developing bias to the developing roller from a high voltage power source, the toner is supplied to the electrostatic latent image on the surface of the photoconductor 1 and visualized as a toner image.

The four process units 10 are arranged in parallel along the surface moving direction of the intermediate transfer belt 15. When forming a full-color image, the toner images of the respective colors (black, cyan, magenta, and yellow) formed on the four photoconductors 1 that are in contact with the intermediate transfer belt 15 are sequentially transferred to the intermediate transfer belt 15 in an overlapping manner. To form a full-color image.

The intermediate transfer belt 15 is stretched around a secondary transfer counter roller 21, a cleaning counter roller 16, four primary transfer rollers 5 (5 a to 5 d ), and a tension roller 20. The secondary transfer counter roller 21, which is a drive roller, receives drive transmission from the drive motor and is rotationally driven in the counterclockwise direction indicated by the arrow in FIG. 2, so that the intermediate transfer belt 15 also rotates counterclockwise in FIG. Rotate around.

The drive source for driving each member of the process unit 10 and the drive source (drive motor) for rotationally driving the secondary transfer counter roller 21 may be independent or common. However, at least the first process unit 10a, which is the process unit 10 for black, and the intermediate transfer belt 15 are generally controlled to be "ON/OFF" at the same time, and the size and cost of the apparatus body can be reduced. Therefore, it is desirable to be common. Further, as a transfer belt tensioning mechanism, the tension roller 20 is biased by a biasing member such as a spring in a direction away from the secondary transfer counter roller 21.

A belt cleaning device 32 is provided on the downstream side in the surface moving direction with respect to the position where the intermediate transfer belt 15 is stretched by the secondary transfer facing roller 21. The belt cleaning device 32 performs cleaning by scraping off transfer residual toner on the intermediate transfer belt 15 with a belt cleaning blade 31 arranged so as to make counter-contact with the intermediate transfer belt 15.

As the belt cleaning device 32, an electrostatic brush method or an electrostatic roller method can be used instead of the blade cleaning method. However, in these electrostatic systems, a cleaning brush member or a cleaning roller member for applying a bias is arranged instead of the belt cleaning blade 31. In this case, pre-charging of the transfer residual toner may be necessary depending on the usage of the image forming apparatus, and the belt cleaning device 32 itself becomes large. In addition, there is a drawback that a system for applying a high voltage power source is added to one or two systems, and an extra operation for cleaning using a bias is required. From this point of view, the blade cleaning method is preferable from the viewpoints of downsizing of the apparatus, cost reduction, and improvement of cleanability.
The transfer residual toner scraped off by the belt cleaning blade 31 of the belt cleaning device 32 passes through the waste toner transport path and is stored in the waste toner storage portion 33 for the intermediate transfer body.

The four primary transfer rollers 5 (a to d) are metal rollers or conductive sponge rollers, and are arranged so as to face the photoconductor 1 with the intermediate transfer belt 15 interposed therebetween to form a primary transfer nip. There is. A toner image on the photoconductor 1 is transferred to the intermediate transfer belt 15 by applying a predetermined primary transfer bias to the primary transfer roller 5 with a single high-voltage power supply.

As the primary transfer roller 5, a metal roller (aluminum, SUS), an ion conductive roller (urethane+carbon dispersion, NBR, hydrin rubber), an electronic conductive type roller (EPDM), or the like can be used.
As the intermediate transfer belt 15, a belt containing a material such as PVDF (vinyl fluoride), ETFE (ethylene-tetrafluoroethylene copolymer), PI (polyimide), PC (polycarbonate), TPE (thermoplastic elastomer) or the like. Can be used. A resin film-shaped endless belt obtained by dispersing a conductive material such as carbon black in these materials can be used as the intermediate transfer belt 15.

A roller member or a belt member is used as a secondary transfer member that forms a secondary transfer nip facing the intermediate transfer belt 15 and transfers the toner image on the surface of the intermediate transfer belt 15 onto the transfer paper P that is a recording medium. Can be used. The printer 100 shown in FIG. 2 includes a roller-shaped secondary transfer roller 25.

The secondary transfer roller 25 is a sponge roller, and an ion conductive roller (urethane+carbon dispersion, NBR, hydrin rubber), an electronic conductive type roller (EPDM) or the like is used. The printer 100 also includes a secondary transfer member cleaning device 27 that removes foreign matter on the surface of the secondary transfer roller 25. The secondary transfer member cleaning device 27 has a secondary transfer member cleaning blade 26 that counter-contacts the surface of the secondary transfer roller 25 that rotates in the clockwise direction in FIG. Then, the secondary transfer roller cleaning blade 26 cleans the secondary transfer roller 25 by scraping off the toner adhering to the surface of the secondary transfer roller 25.

FIG. 3 is a schematic configuration diagram of a printer 100 having a belt-like secondary transfer belt 28 as a secondary transfer member. The printer 100 has the same configuration as the printer 100 shown in FIG. 2 except that the secondary transfer member is the secondary transfer belt 28.
In the case of the configuration including the secondary transfer belt 28 shown in FIG. 3, the secondary transfer belt 28 is rotationally driven by a drive source and a secondary transfer roller 25 to which a secondary transfer bias is applied and a secondary transfer tension roller 29. It is stretched by. Rotational drive is transmitted from a drive motor that is a drive source to rotate the secondary transfer roller 25, and the secondary transfer belt 28 stretched around the secondary transfer roller 25 rotates in the clockwise direction in FIG. 3.

The printer 100 shown in FIG. 3 includes a secondary transfer member cleaning device 27 that removes foreign matter on the surface of the secondary transfer belt 28. The secondary transfer member cleaning device 27 has a secondary transfer member cleaning blade 26 that counter-contacts the surface of the secondary transfer belt 28. Then, the secondary transfer belt cleaning blade 26 cleans the secondary transfer belt 28 by scraping off the toner adhering to the surface of the secondary transfer belt 28.

The transfer paper P is set in the paper feed cassette 22 or the manual paper feed port 42, and is conveyed toward the registration roller pair 24 by the paper feed roller 23 or a conveyance member arranged in the manual paper feed port 42. When the front end of the transfer paper P hits the registration nip of the registration roller pair 24, the conveyance is temporarily stopped.
The transfer paper P that has abutted on the registration nip is restarted to be conveyed at the timing when the front end of the toner image formed on the surface of the intermediate transfer belt 15 reaches the secondary transfer nip. Then, the toner image on the surface of the intermediate transfer belt 15 is transferred to the transfer paper P by applying a predetermined secondary transfer bias from the high voltage power supply.

The printer 100 shown in FIG. 2 has a vertical path as the paper feeding configuration.
The transfer sheet P is separated from the intermediate transfer belt 15 by the curvature of the secondary transfer facing roller 21, the toner image transferred to the transfer sheet P is fixed by the fixing device 40, and then discharged from the discharge port 41 to the outside of the apparatus. It

As the secondary transfer bias, there are two methods including an attractive transfer method and a repulsive transfer method. In the attractive transfer method, a bias of positive polarity is applied to the secondary transfer roller 25, and the secondary transfer counter roller 21 is grounded to form a secondary transfer electric field. In the repulsive transfer method, a negative polarity bias is applied to the secondary transfer counter roller 21 and the secondary transfer roller 25 is grounded to form a secondary transfer electric field.

FIG. 1 is an explanatory diagram of a configuration for performing reverse rotation control of the intermediate transfer belt 15 based on the amount of paper dust Pd collected from the registration roller pair 24.
As shown in FIG. 1, the paper dust Pd attached to one of the two rollers forming the registration roller pair 24 is scraped and collected by the paper dust collecting member 50. As the paper dust collecting member 50, a sheet-shaped member such as a resin film, a metal plate, or a resin plate is used. The paper dust Pd scraped by the paper dust collecting member 50 is conveyed to the paper dust collecting container 52.

The printer 100 of this embodiment detects the amount of paper dust Pd at a predetermined position in the apparatus. Then, based on the detection result, the belt drive motor 54, which is the drive source of the secondary transfer counter roller 21, is controlled to move the intermediate transfer belt 15 in the direction opposite to that at the time of image formation (clock in FIGS. 1 and 2). Reverse rotation control to rotate in the direction of rotation is executed. Depending on the detected amount of paper dust, the execution frequency of the reverse rotation control and the movement amount of the intermediate transfer belt 15 in the reverse rotation direction during the reverse rotation control are controlled.

Since the intermediate transfer belt 15 comes into contact with the transfer paper P at the secondary transfer nip, paper dust generated from the transfer paper P adheres to the surface of the intermediate transfer belt 15 and the space between the belt cleaning blade 31 and the intermediate transfer belt 15. Paper dust may be caught. As a result, the toner may slip through the gap created by the paper dust being caught in the contact portion between the belt cleaning blade 31 and the intermediate transfer belt 15, resulting in defective cleaning.

On the other hand, in the present embodiment, the intermediate transfer belt 15 is reversed to remove foreign matter including the paper dust Pd at the contact portion between the belt cleaning blade 31 and the intermediate transfer belt 15. By the reverse rotation control, it is possible to suppress the paper dust Pd from being caught in the contact portion. Even if the paper dust Pd is already caught in the abutting portion, the paper dust Pd can be moved to the upstream side of the abutting portion in the surface moving direction during image formation by the reverse rotation control, so that the paper dust Pd can be corrected again. It can be removed by the belt cleaning blade 31 during the rotating operation. By performing the reverse rotation control in this manner, it is possible to suppress the occurrence of cleaning failure due to the paper dust Pd being left sandwiched between the contact portions.

However, if the reverse rotation control is regularly performed regardless of the presence or absence of the paper dust Pd caught in the contact portion, the toner accumulated in the edge portion of the belt cleaning blade 31 may be separated from the edge portion. If the toner is exhausted from the edge portion, there arise problems that cleaning failure occurs, and that the edge portion loses lubricity and causes curling or chipping.

In the printer 100 of the present embodiment, the transfer paper transport path in the apparatus (the path through which the transfer paper P passes from the paper feed cassette 22 or the manual paper feed port 42 to the discharge port 41 to be discharged to the outside of the device). ), the accumulation status of the paper powder Pd is detected. Then, the reverse rotation control of the intermediate transfer belt 15 is executed according to the detection result. Therefore, the reverse rotation control can be performed only when there is a possibility that the paper dust Pd has entered the contact portion between the belt cleaning blade 31 and the intermediate transfer belt 15. As a result, it is possible to prevent the occurrence of cleaning failure and the occurrence of curling or chipping due to the deterioration of the lubricity of the edge portion, and it is possible to enhance the cleaning effect.

In the printer 100 of the present embodiment, the paper dust Pd is scraped off from the surface of the roller forming the transfer paper transport path, and the paper dust Pd is used by using one or both of the following “first method” and “second method”. Detect the amount of Pd.
The amount of the paper dust Pd is detected by scraping the paper dust Pd from a roller member satisfying the following requirements (1) to (3), like the roller on the left side of the registration roller pair 24 shown in FIGS. 2 and 3. Is desirable to detect.
That is, (1) the upper surface side of the transfer paper P of the paper feed cassette 22, and (2) the toner adhesion surface side at the time of transfer (contact with the surface of the transfer paper P on the side where the toner image is transferred at the transfer nip). Then, (3) a roller member on the upper side of the paper surface, which is a roller member that conveys the paper P obliquely upward.

[First method]
Next, a first method (hereinafter, referred to as “first method”) for detecting the amount of paper dust Pd at a predetermined position in the apparatus will be described.
In the first method, the weight sensor 51 is used to detect the amount of paper dust Pd collected in the paper dust collecting container 52. The control unit 150 changes the frequency at which the reverse rotation control is executed according to the amount of accumulated paper dust Pd that is the detection result at this time.

No matter what kind of paper the transfer paper P is, the paper dust Pd gradually increases as the paper is passed, but the amount of paper dust Pd generated differs depending on the paper kind. Therefore, in the first method, the execution timing of the reverse rotation control can be controlled so that the reverse rotation control frequency becomes the optimum frequency by detecting the accumulated amount of the paper powder Pd in the paper dust collection container 52. Becomes

As the frequency of the reverse rotation control, the timing at which the reverse rotation control is executed is changed according to the increase in the accumulated amount of the paper dust Pd in the paper dust collecting container 52. For example, in the initial state of using the printer 100, the reverse rotation control is performed once for every 100 sheets of printing, and after the 10,000 sheets have been printed, the reverse rotation control is performed once for every 10 sheets of printing. After that, the reverse rotation control is performed once every five prints.
If the amount of accumulated paper dust Pd at the contact portion becomes excessive, when the intermediate transfer belt 15 is rotated in the reverse direction, the load on the drive transmission member such as the drive gear increases and the life of the drive transmission member may be shortened. is there. On the other hand, by performing the reverse rotation control at an appropriate frequency, it is possible to reduce the load on the drive transmission member that occurs during reverse rotation, and suppress the reduction in the life of the drive transmission member.

Further, as a configuration using the detection result of the weight sensor 51, the frequency of the reverse rotation control may be changed according to the amount of change in the accumulation amount of the paper dust Pd in the paper dust collecting container 52.
Even if the transfer paper P that is passed is the same paper type, the generation amount of the paper dust Pd varies depending on the image area ratio of the toner image that is transferred. The increase amount of the paper powder Pd stored in the collection container 52 is not constant. Therefore, the change in the amount of accumulated paper dust Pd in the paper dust collecting container 52 is calculated, and when there is almost no change, it is determined that the paper dust Pd is small (almost no), and the reverse rotation control is not executed. When the accumulated amount increases, the reverse rotation control is frequently executed.

[Second method]
Next, a second method (hereinafter, referred to as “second method”) for detecting the amount of paper dust Pd at a predetermined position in the apparatus will be described.
In the second method, the optical sensor 53 measures the passing amount of the paper dust Pd on the paper dust collecting member 50, which is the moving path of the paper dust Pd scraped by the paper dust collecting member 50 and toward the paper dust collecting container 52. To detect. Then, the reverse rotation control is executed only when the passing amount exceeds a predetermined amount. As a result, unnecessary reverse rotation control can be eliminated, and it is possible to prevent toner from running out of the edge portion of the belt cleaning blade 31. As a result, it is possible to prevent defective cleaning, and curling or chipping due to deterioration in the lubricity of the edge portion.
As the frequency of the reverse control of the second method, the reverse control is executed when the change amount of the accumulated amount of the paper dust Pd in the paper dust collecting container 52 increases.

FIG. 4 is a block diagram showing an outline of a configuration for executing the reverse rotation control based on the results of the detection means such as the weight sensor 51 and the optical sensor 53.
As shown in FIG. 4, the detection data detected by the detection means is supplied to the control unit 150 via the I/O unit 155. Based on the detection data supplied, the control unit 150 rotates each drive motor such as the belt drive motor 54 in the direction opposite to that at the time of image formation, and reverses the intermediate transfer belt 15 as necessary.

FIG. 5 is a flowchart of control for determining whether to execute reverse rotation control.
As shown in FIG. 5, when the print job is started (“Y” in S1), the paper dust state is detected (S2). If the paper dust state exceeds the threshold value ("Y" in S3), the reverse rotation control is executed at the end of the print job ("Y" in S4) (S5).
Here, when the weight sensor 51 is used to detect the paper dust state, the paper dust state is detected based on the weight of the paper dust Pd collected in the paper dust collecting container 52 or the change amount thereof.
On the other hand, when the optical sensor 53 is used to detect the paper dust state, the presence or absence of passage of a predetermined amount of the paper dust Pd at the above-described predetermined position is detected, and the paper dust state is detected based on the detection result.

FIG. 6 shows a timing chart of the reverse rotation control. FIG. 6A is a timing chart of the operation of performing only reverse rotation, and FIG. 6B is a timing chart of the operation of performing reverse rotation and forward rotation.

“T1” in FIG. 6A indicates the time for reverse rotation, which is “50 [ms]” here. Further, “T2” in FIG. 6A indicates the time when the brake for stopping the rotation after the reverse rotation is turned on, and is “450 [ms]” here.
In the control shown in FIG. 6A, the belt drive motor 54 accelerates in the reverse rotation direction so that the surface of the intermediate transfer belt 15 moves in the reverse direction by a predetermined distance, and the intermediate transfer belt 15 is reversely rotated by inertia. .. Subsequently, the intermediate transfer belt 15 that rotates in the reverse direction is decelerated by the brake. As the reverse rotation amount, the intermediate transfer belt 15 is reversely rotated with the reverse rotation amount being the amount required to remove the foreign matter (paper dust Pd) at the contact portion.

“T3” in FIG. 6B indicates the time for reverse rotation, which is “50 [ms]” here. Further, “T4” in FIG. 6B indicates a time period in which the brake that stops the rotation after the reverse rotation is turned on, and is “450 [ms]” here. “T5” in FIG. 6B indicates the waiting time after the rotation is stopped after the brake that stops the reverse rotation, and is “100 [ms]” here. In addition, “T6” in FIG. 6B indicates the time for performing the forward rotation, and is “50 [ms]” here. Further, “T7” in FIG. 6B indicates a time period in which the brake for stopping the rotation after the normal rotation is turned on, and is “450 [ms]” here. Further, “T8” in FIG. 6B indicates a waiting time after the rotation stops after the brake that stops the forward rotation, and is “100 [ms]” here.

In the reverse rotation control shown in FIG. 6B, in addition to the control shown in FIG. 6A, the normal transfer of the intermediate transfer belt 15 for returning the surface of the intermediate transfer belt 15 to the position before the reverse rotation is performed. Perform rotation. After the reverse rotation, a waiting period is provided to prevent the belt drive motor 54 from being damaged. After that, the intermediate transfer belt 15 is accelerated in the forward rotation direction by the belt drive motor 54 so that the intermediate transfer belt 15 moves in the positive direction (the surface moving direction during image formation) by a certain distance. After that, the intermediate transfer belt 15 is inertially moved in the forward rotation direction, and subsequently, the intermediate transfer belt 15 inertially moved in the forward rotation direction is decelerated by a brake.

The moving speed of the intermediate transfer belt 15 during the reverse rotation and the forward rotation described with reference to FIGS. 6A and 6B may be slower than the steady speed during image formation or the like. ..

In the above-described embodiment, the case where the image carrier that moves in reverse by the reverse movement control is the intermediate transfer belt 15 that is an intermediate transfer member has been described. By performing the reverse movement control of the intermediate transfer belt 15 based on the detection result of the detection means such as the weight sensor 51 or the optical sensor 53, the reverse movement control of the intermediate transfer belt 15 can be executed at an appropriate timing. For this reason, it is possible to prevent the belt cleaning blade 31, which is a cleaning member, from being turned over or chipped, or cleaning failure. In the configuration in which the intermediate transfer belt 15 is controlled to move in the reverse direction, the transfer unit that transfers the toner image from the intermediate transfer belt 15, which is the image carrier, to the recording medium is the secondary transfer roller 25.

The image carrier that performs the reverse movement control is not limited to the intermediate transfer belt 15. The photoconductor 1, which is a latent image carrier in the printer 100, may also be configured to perform reverse movement control based on the detection result of the detection means. In the printer 100 of the present embodiment, the photoconductor 1 does not come into direct contact with the transfer paper P, but the paper dust adhering to the intermediate transfer belt 15 contacting the transfer paper P moves to the photoconductor 1 at the primary transfer nip, and Paper powder may adhere to the surface of the body 1. Then, paper dust may be caught between the photoconductor cleaning blade 6 and the photoconductor 1. As a result, the toner may slip through the gap created by the paper dust being sandwiched between the abutting portions of the photoconductor cleaning blade 6 and the photoconductor 1, resulting in poor cleaning. If the reverse movement control is performed at a predetermined timing regardless of the amount of paper dust in order to prevent this cleaning failure, the photoconductor cleaning blade 6 may be turned over or chipped, or cleaning failure may occur.

On the other hand, by performing the reverse movement control of the photoconductor 1 based on the detection result of the detection unit, the reverse movement control of the photoconductor 1 can be executed at an appropriate timing. For this reason, it is possible to prevent the photosensitive member cleaning blade 6 as a cleaning member from being turned over or chipped, or from being defective in cleaning. In the configuration in which the photoconductor 1 is controlled to move in the reverse direction, the transfer unit that transfers the toner image from the photoconductor 1, which is the image carrier, to the recording medium is the intermediate transfer belt 15 and the secondary transfer roller 25.

Further, the surface moving body for performing the reverse movement control is not limited to the image carrier such as the intermediate transfer belt 15 and the photoconductor 1. The secondary transfer roller 25, which is a transfer member in the printer 100, may also be configured to perform reverse movement control based on the detection result of the detection means.
When the toner attached to the intermediate transfer belt 15 reaches the secondary transfer nip at the timing when the transfer sheet P is not present, the toner is transferred to the secondary transfer roller 25. Further, since the secondary transfer roller 25 comes into contact with the transfer paper P, paper dust may adhere to it. For this reason, paper dust may be caught between the secondary transfer member cleaning blade 26 and the secondary transfer roller 25.

As a result, the toner may slip through the gap created by the paper dust being caught in the contact portion between the secondary transfer member cleaning blade 26 and the secondary transfer roller 25, and cleaning failure may occur. In order to prevent this cleaning failure, if the reverse movement control is performed at a predetermined timing irrespective of the amount of paper dust, the secondary transfer member cleaning blade 26 may be turned over or chipped, or cleaning failure may occur. On the other hand, by performing the reverse movement control of the secondary transfer roller 25 based on the detection result of the detection means, the reverse movement control of the secondary transfer roller 25 can be executed at an appropriate timing. For this reason, it is possible to prevent the secondary transfer member cleaning blade 26, which is a cleaning member, from being turned over or chipped, or occurrence of cleaning failure.
Here, the case where the transfer member is the secondary transfer roller 25 shown in FIG. 2 has been described, but even if the transfer member is the secondary transfer belt 28 shown in FIG. 3, it is based on the detection result of the detection means. It is possible to apply a configuration for performing all reverse movement control.

In the above-described embodiment, the weight sensor 51 or the optical sensor 53 detects the amount of the paper powder Pd collected from one of the rollers of the registration roller pair 24 among the members arranged in the transfer paper conveyance path. The location for collecting the paper dust Pd for detecting the amount is not limited to the registration roller pair 24, but may be another location on the transfer paper transport path.

For example, the air on the upper surface side of the transfer paper P of the paper feed cassette 22 may be sucked, the amount of paper dust Pd contained in the sucked air may be detected, and the reverse rotation control may be executed based on the detection result.
Further, when performing reverse control of the intermediate transfer belt 15 and the photoconductor 1, the amount of paper dust Pd removed by the secondary transfer member cleaning blade 26 from the surface of the secondary transfer roller 25 is detected, and based on the detection result. The reverse rotation control may be executed. Further, when the reverse rotation control of the photoconductor 1 is performed, the amount of the paper dust Pd removed by the belt cleaning blade 31 from the surface of the intermediate transfer belt 15 which is the toner adhering surface side at the secondary transfer nip is detected, and the detection is performed. The reverse rotation control may be executed based on the result.
Further, from a roller (paper feed roller 23, a paper feed roller when there is a paper feed roller between the paper feed roller 23 and the registration roller pair 24) that comes into contact with the upper surface of the transfer paper P to be carried from the paper feed cassette 22. The amount of the paper dust Pd scraped may be detected by scraping the paper dust Pd.

In the above-described embodiment, the removing unit that removes the foreign matter (paper dust Pd) on the surface of the surface moving body (roller member of the registration roller pair 24) is the blade-shaped paper dust collecting member 50 that contacts the surface moving body. However, the removing means is not limited to the configuration of contacting the surface moving body. Any structure capable of removing foreign matter and detecting the amount thereof, such as removing foreign matter by air suction or air blowing without contact with the surface moving body, or a configuration of removing foreign matter using static electricity Non-contact removing means may be used.

The image forming apparatus according to the present invention is not limited to a printer, but can be applied to other image forming apparatuses such as a copying machine and a facsimile.

What has been described above is an example, and the following unique effects can be obtained.

(Aspect 1)
An image carrier such as the intermediate transfer belt 15 or the photoconductor 1 that carries a toner image, a transfer unit such as a secondary transfer roller 25 that transfers the toner image on the surface of the image carrier to a recording medium, and an image carrier Cleaning means such as a belt cleaning device 32 or a photoconductor cleaning device 7 having a cleaning member such as a belt cleaning blade 31 or a photoconductor cleaning blade 6 contacting the surface, and the surface of the image bearing member in a direction opposite to that at the time of image formation. In an image forming apparatus such as a printer 100 including a control unit such as a control unit 150 that executes a reverse movement control for moving the paper dust Pd removed from a predetermined position (a roller surface of the registration roller pair 24) in the apparatus. In the paper dust collecting container 52, on the paper dust collecting member 50, or the like), a detection unit such as a weight sensor 51 or an optical sensor 53 for detecting the amount of foreign matter such as paper dust Pd is provided, and the control unit is the detection unit. It is characterized in that the reverse movement control is executed based on the detection result.
In the image forming apparatus described in Patent Document 1, the frequency of the reverse movement control is varied depending on the surface roughness of the recording medium, but at a predetermined timing, the reverse movement control stays at the contact portion between the image carrier and the cleaning member. The reverse movement control is executed regardless of the amount of foreign matter (paper dust Pd) present. For this reason, the reverse movement control is executed in a state where the amount of foreign matter staying at the contact portion is small, so that the toner disappears from the contact portion and the cleaning failure or the lubricity at the contact portion is deteriorated and the cleaning member is turned up. There were cases where chips and chips occurred. In addition, due to the fact that the reverse movement control is not executed until a predetermined timing, even if the amount of foreign matter staying at the contact portion is large, the toner passes through the contact portion and scumming on the recording medium is prevented. Poor cleaning could occur. As described above, in the conventional image forming apparatus that executes the reverse movement control of the image bearing member, there is a possibility that the cleaning member may be turned over or chipped, or defective cleaning may occur.
As a result of intensive studies by the present inventors, it was found that the amount of foreign matter staying at the contact portion between the image carrier and the cleaning member is related to the amount of foreign matter at a predetermined position in the apparatus. ..
Aspect 1 performs reverse movement control based on a detection result of a detection unit that detects the amount of foreign matter at a predetermined position in the apparatus such as a storage unit that stores the foreign matter collected from a member arranged on the recording medium conveyance path. Run. As a result, the reverse movement control of the image carrier can be executed at an appropriate timing when the amount of foreign matter staying in the contact portion is neither too small nor too large. Therefore, it is possible to prevent the cleaning member from being turned over, chipped, or defective in cleaning.

(Aspect 2)
In the first aspect, the image carrier has an intermediate transfer belt on which a toner image formed on another image carrier such as the photoconductor 1 is transferred, and the transferred toner image is transferred to a transfer target such as a transfer paper P. It is characterized in that it is an intermediate transfer member such as 15.
According to this, the reverse movement control of the intermediate transfer member can be executed at an appropriate timing, and it is possible to prevent the cleaning member (the belt cleaning blade 31 or the like) that comes into contact with the intermediate transfer member from being turned over or chipped, or the occurrence of defective cleaning.
In the printer 100 of the embodiment, the case where the transfer target to which the toner image of the intermediate transfer member is transferred is the recording medium (transfer paper P) has been described, but the transfer target is not limited to the recording medium, and other intermediate transfer may be performed. It may be the body.

(Aspect 3)
In Aspect 1, the latent image is formed on the surface of the image bearing member by the latent image forming means such as the exposure device 30, and the latent image is developed by the developing means such as the developing device 4, and the toner image is carried, and the toner is carried. It is characterized in that it is a latent image carrier such as the photoconductor 1 that transfers an image to a transfer target such as the intermediate transfer belt 15.
According to this, the reverse movement control of the latent image carrier can be executed at an appropriate timing, and the cleaning member (photoreceptor cleaning blade 6 or the like) that comes into contact with the latent image carrier can be prevented from being turned over or chipped, or the cleaning failure can occur. It can be prevented.
In the printer 100 according to the embodiment, the transfer target to which the toner image on the latent image carrier is transferred is the intermediate transfer member (intermediate transfer belt 15), but the transfer target is not limited to the intermediate transfer member. The present invention can be applied as a configuration for performing reverse movement control of the latent image carrier even if the toner image on the latent image carrier is directly transferred to the recording medium such as the transfer paper P.

(Aspect 4)
In modes 1 to 3, in the reverse movement control, control for performing only an operation (reverse rotation or the like) of moving the surface of the image carrier in a direction opposite to that in image formation (control of FIG. 6A), or image Control for performing an operation of moving the surface of the carrier in a direction opposite to that during image formation (reverse rotation, etc.) and an operation for moving in the same direction as during image formation (forward rotation, etc.) (control of FIG. 6B) It is characterized by executing.
According to this, in the reverse movement control, in the control in which only the operation of moving the image carrier in the direction opposite to that at the time of image formation is performed, the reverse movement is performed only for the time required to remove the foreign matter from the contact portion. Since the reverse movement control ends, the time required for the reverse movement control can be minimized.
On the other hand, as the reverse movement control, in the control of performing the operation of moving the image carrier in the direction opposite to that at the time of image formation and the operation of moving it in the same direction as that at the time of image formation, the operation of moving the image carrier in the opposite direction is performed. The foreign matter redeposited on the surface can be cleaned with a cleaning member before image formation.

(Aspect 5)
An image carrier such as an intermediate transfer belt 15 that carries a toner image, and a transfer such as a secondary transfer nip that faces the image carrier and transfers the toner image on the surface of the image carrier to a recording medium such as transfer paper P. A transfer member such as a secondary transfer roller 25 that forms a portion, a cleaning unit such as a secondary transfer member cleaning device 27 that brings a cleaning member such as a secondary transfer member cleaning blade 26 into contact with the surface of the transfer member, and the transfer member. In the image forming apparatus such as the printer 100 including the control unit such as the control unit 150 that executes the reverse movement control for moving the surface of the sheet in the direction opposite to that in the image formation, a predetermined position in the apparatus (the registration roller pair 24 Control is provided with a detection unit such as a weight sensor 51 or an optical sensor 53 that detects the amount of foreign matter in the paper dust collecting container 52 that collects the paper dust Pd removed from the roller surface or on the paper dust collecting member 50). The means is characterized by executing the reverse movement control based on the detection result of the detecting means.
According to this, similarly to the above-described aspect 1 in which the cleaning target by the cleaning unit is the image carrier, the reverse movement control of the image carrier can be executed at an appropriate timing even when the cleaning target is the transfer member. It is possible to prevent curling and chipping, or occurrence of defective cleaning.

(Aspect 6)
In the fifth aspect, in the reverse movement control, control is performed only to move the surface of the transfer member in a direction opposite to that in image formation (reverse rotation, etc.) (control in FIG. 6A), or Control (control of FIG. 6B) for performing an operation of moving the surface in the direction opposite to the image formation (reverse rotation, etc.) and an operation of moving the surface in the same direction as the image formation (forward rotation, etc.) It is characterized by that.
According to this, in the reverse movement control, in the control in which only the operation of moving the transfer member in the direction opposite to that at the time of image formation is performed, the transfer member is moved in the opposite direction for the time necessary to take out the foreign matter from the contact portion and reversely moved. Since the movement control ends, the time for reverse movement control can be minimized.
On the other hand, in the reverse movement control, in the control of performing the operation of moving the transfer member in the direction opposite to that at the time of image formation and the operation of moving it in the same direction as that at the time of image formation, the surface of the image carrier is moved by the movement in the opposite direction. The foreign matter redeposited on the can be cleaned with a cleaning member before image formation.

(Aspect 7)
In any one of Aspects 1 to 6, the detection means collects from a member (a roller member or the like that constitutes the registration roller pair 24) arranged in a recording medium conveyance path (transfer sheet conveyance path or the like) in the apparatus. The feature is that the amount of foreign matter is detected.
According to this, by detecting the amount of the foreign matter adhering to the member arranged on the conveyance path of the recording medium, there is a correlation with the amount of the foreign matter adhering to the image carrier or the transfer member and generated from the recording medium. It is possible to detect the amount of foreign matter.

(Aspect 8)
In Mode 7, a surface moving body (a roller member or the like forming the registration roller pair 24) that applies a conveying force to the recording medium in the conveying path, and a paper dust collecting member 50 that removes foreign matters on the surface of the surface moving body. And a detecting unit such as the weight sensor 51 detects the weight of the foreign matter removed by the removing unit.
According to this, by changing the frequency of the reverse movement control according to the amount of the foreign matter removed by the removing means, the reverse movement control of the image carrier or the transfer member can be executed at an appropriate timing, and the cleaning member can be turned up or down. It is possible to prevent chipping or defective cleaning. By executing the reverse movement control at an appropriate timing, it is possible to prevent the frequency of the reverse movement control from becoming excessive, and reduce the load on the drive transmission member that occurs when moving the image carrier or the transfer member in the reverse direction. Can be planned.

(Aspect 9)
In Mode 7, a surface moving body (a roller member or the like forming the registration roller pair 24) that applies a conveying force to the recording medium in the conveying path, and a paper dust collecting member 50 that removes foreign matters on the surface of the surface moving body. And a detection unit such as the weight sensor 51 for detecting the amount of change in the weight of the foreign matter removed by the removal unit.
According to this, by changing the frequency of the reverse movement control according to the amount of change in the weight of the foreign matter removed by the removing means, the reverse movement control of the image carrier or the transfer member can be executed at an appropriate timing, and the cleaning member It is possible to prevent curling and chipping, or occurrence of defective cleaning. By executing the reverse movement control at an appropriate timing, it is possible to prevent the frequency of the reverse movement control from becoming excessive, and reduce the load on the drive transmission member that occurs when moving the image carrier or the transfer member in the reverse direction. Can be planned.

(Aspect 10)
In Mode 7, a surface moving body (a roller member or the like forming the registration roller pair 24) that applies a conveying force to the recording medium in the conveying path, and a scraping device that comes into contact with the surface moving body and scrapes foreign matter on the surface. A member (paper dust collecting member 50 and the like) and a containing portion such as a paper dust collecting container 52 for containing the foreign matter scraped by the scraping member are provided, and the detection means such as the optical sensor 53 is scraped by the scraping member. It is characterized in that the amount of foreign matter passing through the path of movement of the foreign matter (such as the upper surface of the paper dust collecting member 50) toward the storage unit is detected.
According to this, by performing the reverse movement control only when the foreign matter is detected by the detection means in the movement path of the foreign matter, the reverse movement control can be executed at an appropriate timing, and the cleaning member is curled or chipped, or It is possible to prevent the occurrence of cleaning failure. By executing the reverse movement control at an appropriate timing, it is possible to prevent the frequency of the reverse movement control from becoming excessive, and reduce the load on the drive transmission member that occurs when moving the image carrier or the transfer member in the reverse direction. Can be planned.

DESCRIPTION OF SYMBOLS 1 photoconductor 2 charging roller 3 exposure light 4 developing device 5 primary transfer roller 6 photoconductor cleaning blade 7 photoconductor cleaning device 10 process unit 10a first process unit 15 intermediate transfer belt 16 cleaning facing roller 20 tension roller 21 secondary transfer facing Roller 22 Paper feed cassette 23 Paper feed roller 24 Registration roller pair 25 Secondary transfer roller 26 Secondary transfer member cleaning blade 27 Secondary transfer member cleaning device 28 Secondary transfer belt 29 Secondary transfer tension roller 30 Exposure device 31 Belt cleaning blade 32 belt cleaning device 33 waste toner storage unit for intermediate transfer body 40 fixing device 41 discharge port 42 manual paper feed port 50 paper dust collecting member 51 weight sensor 52 paper dust collecting container 53 optical sensor 54 belt drive motor 100 printer 150 control unit 155 I/O unit P Transfer paper Pd Paper dust

JP, 2017-90820, A

Claims (10)

An image carrier that carries a toner image,
Transfer means for transferring the toner image on the surface of the image carrier to a recording medium,
Cleaning means having a cleaning member that contacts the surface of the image carrier,
An image forming apparatus comprising: a control unit that executes a reverse movement control for moving the surface of the image carrier in a direction opposite to that in image formation.
A detection means for detecting the amount of foreign matter at a predetermined position in the device,
The image forming apparatus, wherein the control unit executes the reverse movement control based on a detection result of the detection unit. The image forming apparatus according to claim 1,
An image forming apparatus, wherein the image carrier is an intermediate transfer member to which a toner image formed on another image carrier is transferred and which transfers the transferred toner image to a transfer target. The image forming apparatus according to claim 1,
The latent image carrier has a latent image formed on its surface by a latent image forming means, carries the toner image by developing the latent image by a developing means, and transfers the carried toner image to a transfer target. An image forming apparatus comprising: The image forming apparatus according to any one of claims 1 to 3,
In the reverse movement control, a control is performed only to move the surface of the image carrier in a direction opposite to that during image formation, or an operation to move the surface of the image carrier in a direction opposite to that during image formation. An image forming apparatus, wherein control is performed to perform an operation of moving in the same direction as when the image is formed. An image carrier that carries a toner image,
A transfer member that faces the image carrier and forms a transfer unit that transfers the toner image on the surface of the image carrier to a recording medium;
Cleaning means for bringing a cleaning member into contact with the surface of the transfer member,
An image forming apparatus comprising: a control unit that executes reverse movement control for moving the surface of the transfer member in a direction opposite to that in image formation.
A detection means for detecting the amount of foreign matter at a predetermined position in the device,
The image forming apparatus, wherein the control unit executes the reverse movement control based on a detection result of the detection unit. The image forming apparatus according to claim 5,
In the reverse movement control, control is performed only to move the surface of the transfer member in a direction opposite to that during image formation, or operation in which the surface of the transfer member is moved in a direction opposite to that during image formation and image formation. An image forming apparatus, which executes a control for performing an operation of moving in the same direction as time. The image forming apparatus according to any one of claims 1 to 6,
The image forming apparatus, wherein the detecting unit detects an amount of the foreign matter collected from a member arranged in a conveyance path of the recording medium in the apparatus. The image forming apparatus according to claim 7,
A surface moving body that applies a carrying force to the recording medium in the carrying path;
A removing means for removing the foreign matter on the surface of the surface moving body,
The image forming apparatus, wherein the detecting means detects the weight of the foreign matter removed by the removing means. The image forming apparatus according to claim 7,
A surface moving body that applies a carrying force to the recording medium in the carrying path;
A removing means for removing the foreign matter on the surface of the surface moving body,
The image forming apparatus, wherein the detection unit detects the amount of change in the weight of the foreign matter removed by the removal unit. The image forming apparatus according to claim 7,
A surface moving body that applies a carrying force to the recording medium in the carrying path;
A scraping member that comes into contact with the surface moving body and scrapes off the foreign matter on the surface thereof,
A storage unit for storing the foreign matter scraped by the scraping member,
The image forming apparatus, wherein the detection unit detects an amount of the foreign matter that has passed along a movement path of the foreign matter that is scraped by the scraping member and headed toward the accommodation portion.

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