JP2018072693A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the occurrence of failure in cleaning of an image carrier in an image forming apparatus.SOLUTION: An image forming apparatus 100 transfers toner images formed on the surfaces of photoreceptor drums 11Y, 11M, 11C, and 11K to an intermediate transfer belt 17 and secondarily transfers the toner images transferred to the intermediate transfer belt 17 to a sheet P, and comprises: a cleaning blade 21 that is in contact with the intermediate transfer belt 17 to remove a toner remaining on the intermediate transfer belt 17; a retaining part 30 that retains the toner removed by the cleaning blade 21; and a control part that forms a toner band 300 on the intermediate transfer belt 17 with the toner retained in the retaining part 30, separates and removes a toner having a predetermined amount of charge from the toner band 300 on the intermediate transfer belt 17, subsequently detects the resistance of the remaining toner band 300, and supplies a new toner to the retaining part 30 according to a result of the detection.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an image forming apparatus.

  2. Description of the Related Art Conventionally, there is known an image forming apparatus that forms a toner image on a photosensitive member, transfers the toner image to an intermediate transfer belt (image carrier), and transfers the toner image on the intermediate transfer belt onto a sheet. In such an image forming apparatus, in order to remove toner remaining on the intermediate transfer belt after transfer to the paper, the intermediate transfer belt contacts the intermediate transfer belt on the downstream side in the rotation direction of the intermediate transfer belt with respect to the transfer position to the paper. There is a configuration called a blade cleaning system in which a blade that scrapes off remaining toner is provided (see, for example, Patent Document 1).

In the blade cleaning method, it is necessary to press the blade against the intermediate transfer belt with a force of a certain size or more in order to scrape off the toner reliably, and friction is generated between the intermediate transfer belt and the blade. Friction may cause blade edge wear, damage, and the like.
Therefore, the toner removed by the blade is temporarily stored in the vicinity of the blade, and the blade is configured so that the toner is always present at the pressure contact portion between the blade and the intermediate transfer belt (external additive is replenished). There is known a configuration that imparts lubricity to the blade to prevent abrasion or damage of the blade edge. At this time, the amount of toner stored is kept at the required amount.

JP 2013-167808 A

However, in such a configuration, since the toner scraped by the blade is used, the quality of the toner is not constant, and there is a possibility that a cleaning failure may occur.
Specifically, for example, when the amount of foreign matter such as paper dust mixed in the toner is large, there is a case where foreign matter is caught in the blade and cleaning failure is caused. In addition, when there are many deteriorated toners with insufficient external additives in the toner, the external additive is not supplied to the blade, so that the desired effect of preventing wear or damage of the blade edge cannot be obtained, resulting in poor cleaning. There was a case.

  An object of the present invention is to suppress occurrence of defective cleaning of an image carrier in an image forming apparatus.

In order to solve the above problems, according to the present invention,
In an image forming apparatus that primarily transfers a toner image formed on the surface of a photosensitive member to an image carrier, and secondarily transfers the toner image on the image carrier to a transfer member.
A cleaning member that contacts the image carrier and removes toner remaining on the image carrier after secondary transfer;
A reservoir for storing toner removed by the cleaning member;
A toner band forming unit that forms a toner band of toner stored in the storage unit on the image carrier;
A toner separation / removal unit that separates and removes toner having a predetermined charge amount from the toner band on the image carrier;
A resistance detection unit for detecting the resistance of the toner band after passing through the toner separation and removal unit;
A toner supply unit that supplies new toner to the storage unit according to a detection result of the resistance detection unit;
It is characterized by providing.

  According to the present invention, it is possible to suppress the occurrence of poor cleaning of the image carrier in the image forming apparatus.

1 is a schematic configuration diagram of an image forming apparatus in an embodiment of the present invention. 2 is a block diagram illustrating a control configuration of the image forming apparatus. FIG. It is a schematic diagram which shows the structure of a cleaning mechanism. It is a schematic diagram which shows the structure of a cleaning mechanism. 6 is a flowchart illustrating a toner supply process. FIG. 6 is a diagram for explaining toner supply processing.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

[Configuration of Image Forming Apparatus]
First, the configuration of the image forming apparatus in the present embodiment will be described.

FIG. 1 is a schematic configuration diagram of the image forming apparatus 100. FIG. 2 is a block diagram illustrating a control configuration of the image forming apparatus 100.
As shown in FIGS. 1 and 2, the image forming apparatus 100 includes an image forming unit 10, a cleaning mechanism 200, a toner adhesion amount detection unit 40, a paper feeding unit 50, a control unit 61, an operation unit 62, a display unit 63, and a storage unit. 64, a communication unit 65, and the like, and each unit is connected by a bus.

  The image forming unit 10 includes photosensitive drums 11Y, 11M, 11C, and 11K corresponding to yellow (Y), magenta (M), cyan (C), and black (K) colors, and charging units 12Y, 12M, 12C, and 12K. , Exposure units 13Y, 13M, 13C, 13K, developing units 14Y, 14M, 14C, 14K, primary transfer rollers 15Y, 15M, 15C, 15K as primary transfer units, photoconductor cleaning units 16Y, 16M, 16C, 16K, An intermediate transfer belt 17 as an image carrier, a secondary transfer roller pair 18 as a secondary transfer portion, and a fixing portion 19 are provided.

The charging units 12Y, 12M, 12C, and 12K uniformly charge the photosensitive drums 11Y, 11M, 11C, and 11K.
The exposure units 13Y, 13M, 13C, and 13K are composed of laser light sources, polygon mirrors, lenses, and the like, and scan and expose the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11K with laser beams based on the image data of each color. An electrostatic latent image is formed.
The developing units 14Y, 14M, 14C, and 14K store developers corresponding to yellow (Y), magenta (M), cyan (C), and black (K), respectively, and are photosensitive drums 11Y, 11M, and 11C. , 11K, the toner of each color is attached to the electrostatic latent image, and development is performed.

  As the developer, for example, a two-component developer composed of toner and carrier is used. For the toner constituting the two-component developer, for example, silica having a particle size of 10 to 1000 nm, titania, etc. for the purpose of imparting fluidity to the toner and improving charging property, developing property, transfer property and cleaning property, etc. An external additive made of alumina or the like is added.

The primary transfer rollers 15Y, 15M, 15C, and 15K sequentially transfer the toner images of the respective colors formed on the photosensitive drums 11Y, 11M, 11C, and 11K onto the intermediate transfer belt 17 (primary transfer).
Specifically, the primary transfer rollers 15Y, 15M, 15C, and 15K are respectively provided with bias application units 15a, 15b, 15c, and 15d, and the primary transfer rollers 15Y, 15M are provided by the bias application units 15a, 15b, 15c, and 15d, respectively. , 15C, and 15K, and a toner image on the photosensitive drums 11Y, 11M, 11C, and 11K is transferred to the intermediate transfer belt 17.
As a result, a color toner image is formed on the intermediate transfer belt 17 by superimposing the four color toner images.
The primary transfer rollers 15Y, 15M, 15C, and 15K can be applied with a bias having a polarity opposite to that when the toner image is transferred to the intermediate transfer belt 17 by the bias applying units 15a, 15b, 15c, and 15d. It is.
The primary transfer rollers 15Y, 15M, 15C, and 15K include driving units m1, m2, m3, and m4, respectively. The primary transfer rollers 15Y, 15M, and 15C are driven by the driving units m1, m2, m3, and m4. , 15K are configured to be able to contact and separate from the intermediate transfer belt 17.

  The photoconductor cleaning units 16Y, 16M, 16C, and 16K remove the toner remaining on the peripheral surfaces of the photoconductor drums 11Y, 11M, 11C, and 11K after the transfer.

  The intermediate transfer belt 17 is an endless belt, is stretched by a plurality of rollers (a driving roller, a driven roller, etc.), and is driven to rotate in a direction indicated by an arrow A in FIG.

The secondary transfer roller pair 18 collectively transfers the color toner image formed on the intermediate transfer belt 17 onto one surface of the sheet P as a transfer target supplied from the sheet feeding unit 50 (secondary transfer). Next transfer).
The secondary transfer roller pair 18 is provided with a measuring unit 18A that applies a constant current and measures the value of the feedback voltage.

  The fixing unit 19 fixes the toner transferred on the paper P onto the paper P by heating and pressing.

  The cleaning mechanism 200 removes residual toner, paper dust, and the like that are not transferred to the paper P from the intermediate transfer belt 17 after the color toner image is transferred to the paper P by the secondary transfer roller pair 18, and performs intermediate transfer. This is a mechanism for cleaning the belt 17. Details of the configuration of the cleaning mechanism 200 will be described later.

The toner adhesion amount detection unit 40 is provided downstream of the cleaning mechanism 200 in the rotational direction of the intermediate transfer belt 17.
The toner adhesion amount detection unit 40 includes, for example, an IDC (Image Density Control) sensor, a line sensor, and the like.
The toner adhesion amount detection unit 40 is for detecting the toner adhesion amount in the toner band 300 when a later-described toner band 300 is formed on the intermediate transfer belt 17.

  The paper feed unit 50 is provided in the lower part of the image forming apparatus 100 and includes a detachable paper feed cassette 51. The paper P stored in the paper feed cassette 51 is sent out one by one from the uppermost one by the paper feed roller 52 to the transport path.

  The control unit 61 is configured by a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and comprehensively controls the processing operation of each unit of the image forming apparatus 100. The CPU reads various processing programs stored in the ROM, expands them in the RAM, and executes various processes according to the expanded programs.

  The operation unit 62 includes a touch panel formed so as to cover the display screen of the display unit 63 and various operation buttons such as numeric buttons and a start button, and outputs an operation signal based on a user operation to the control unit 61.

  The display unit 63 is configured by an LCD (Liquid Crystal Display), and displays various screens according to instructions of a display signal input from the control unit 61.

  The storage unit 64 includes a storage device such as a nonvolatile semiconductor memory or a hard disk, and stores data related to various processes.

  The communication unit 65 transmits and receives data to and from an external device connected to a network such as a LAN (Local Area Network).

[Configuration of cleaning mechanism]
Next, the configuration of the cleaning mechanism 200 will be described.

FIG. 3 is a schematic diagram showing the configuration of the cleaning mechanism 200. FIG. 4 is a view for explaining the operation of the cleaning blade 21 in the cleaning mechanism 200.
Each part constituting the cleaning mechanism 200 is elongated along the width direction of the intermediate transfer belt 17.

  As shown in FIG. 3, the cleaning mechanism 200 includes a casing CA, a cleaning unit 20 provided in the casing CA, and a storage unit 30 provided below the cleaning unit 20 in the casing CA. .

  The casing CA is a housing that covers each member constituting the cleaning unit 20 and the storage unit 30.

  The cleaning unit 20 contacts the intermediate transfer belt 17 with a cleaning blade (cleaning member) 21, a blade holder 22 that holds the cleaning blade 21, a pressure spring 23 that is connected to the base end of the blade holder 22, and the cleaning blade 21. A drive unit 24 and the like to be separated are provided.

The cleaning blade 21 is a plate body made of an elastic body such as urethane rubber having a length of about 10 mm and a thickness of about 2 mm, for example.
The cleaning blade 21 comes into contact with the intermediate transfer belt 17 whose front end circulates, thereby scraping off, for example, toner or paper powder on the intermediate transfer belt 17 to clean the intermediate transfer belt 17.
Specifically, the cleaning blade 21 is fixed to the blade holder 22 at the base end, and comes into contact with the intermediate transfer belt 17 in a state where the front end faces in the direction opposite to the rotation direction of the intermediate transfer belt 17 (counter direction). . The contact angle of the cleaning blade 21 with respect to the intermediate transfer belt 17 is set to be about 25 °, for example. The pressure contact force (contact pressure) with which the cleaning blade 21 is pressed against the intermediate transfer belt 17 is set to be, for example, about 30 N / m.

  The blade holder 22 is rotatably attached to a support shaft G provided in the casing CA, and holds the cleaning blade 21.

  The pressing spring 23 urges the blade holder 22 to rotate counterclockwise around the support shaft G, and presses against the intermediate transfer belt 17 with the tip of the cleaning blade 21 facing the counter direction. It arrange | positions so that it may press-contact with C. With this configuration, when the intermediate transfer belt 17 rotates, the cleaning blade 21 can scrape and remove the toner on the intermediate transfer belt 17.

The drive unit 24 is a drive motor that rotates the blade holder 22, and rotates the blade holder 22 about the support shaft G in the clockwise direction under the control of the control unit 61.
As a result, as shown in FIG. 4, the tip of the cleaning blade 21 is separated from the intermediate transfer belt 17, and the toner stored in the storage unit 30 passes through the gap, so that the toner of the stored toner is transferred onto the intermediate transfer belt 17. A band 300 is formed.
The blade holder 22 and the cleaning blade 21 can return to their original positions by the contraction force of the pressing spring 23.

The storage unit 30 stores the toner scraped off by the cleaning unit 20.
The storage unit 30 includes a storage roller 31 installed below the cleaning blade 21, a storage sheet 32 as a regulating member, a holding member 33 that holds the storage sheet 32, and a scattering prevention sheet installed further below the storage roller 31. 34 etc. are provided.

The storage roller 31 is, for example, a roller member made of foamed urethane or the like having a diameter of about 17 mm, and is located upstream of the pressure contact position C between the cleaning blade 21 and the intermediate transfer belt 17 in the rotational direction of the intermediate transfer belt 17. The transfer belt 17 is disposed so as to contact the transfer belt 17. The amount of biting of the storage roller 31 into the intermediate transfer belt 17 is set to about 1 mm.
The storage roller 31 is rotated in a width direction (a direction along the rotation direction of the intermediate transfer belt 17) with respect to the rotation direction of the intermediate transfer belt 17 by a driving unit (not shown) at a contact position with the intermediate transfer belt 17. Is configured to do.

The storage sheet 32 is a plate made of, for example, a PET (polyethylene terephthalate) sheet having a thickness of about 0.1 mm.
One end of the storage sheet 32 contacts the surface of the storage roller 31 at a position opposite to the contact position between the storage roller 31 and the intermediate transfer belt 17, and the other end is provided above the storage roller 31. It is fixed to the member 33 and restricts the toner scraped off by the cleaning blade 21 from being discharged outside the storage space 35.

  The holding member 33 is fixed to a protruding portion inside the casing CA by a screw or the like, and holds the storage sheet 32.

With the above configuration, a space surrounded by the intermediate transfer belt 17, the storage roller 31, and the storage sheet 32 is formed. This space forms a storage space 35 in which the toner scraped from the surface of the intermediate transfer belt 17 by the cleaning blade 21 is stored.
A constant amount of toner stored in the storage space 35 is maintained. When the amount exceeds the specified amount, one end of the storage sheet 32 is separated from the surface of the storage roller 31 and discharged to the outside of the storage space 35. It will be.

  The scattering prevention sheet 34 is a plate body made of, for example, a PET (polyethylene terephthalate) sheet. One end of the anti-scattering sheet 34 is bonded to the bottom of the casing CA facing the intermediate transfer belt 17, and the other end is installed so as to be in light contact with the intermediate transfer belt 17, and the toner inside the casing CA falls downward. To prevent that.

[Toner supply processing to cleaning mechanism]
Next, toner supply processing for the cleaning mechanism 200 in the image forming apparatus 100 of the present embodiment will be described.

As a premise, in the image forming apparatus 100 of the present embodiment, during the image formation, the cleaning blade 21 of the cleaning unit 20 scrapes off the remaining toner that has not been transferred from the intermediate transfer belt 17 to the paper P. The toner thus stored is stored in the storage space 35 of the storage unit 30. Since the stored toner is always conveyed to the press contact position C as the intermediate transfer belt 17 rotates, the external additive is replenished to the press contact position C to make the cleaning blade 21 lubricous. Has been granted.
At this time, a good quality of the stored toner is effective for suppressing the occurrence of poor cleaning. In the image forming apparatus 100 of the present embodiment, at an appropriate timing such as after the end of a job or between images. A process (toner supply process) for maintaining the quality of the stored toner at a constant level is executed.

  FIG. 5 is a flowchart showing the toner supply process. FIG. 6 is a diagram for explaining the toner supply process.

First, the control unit 61 separates the cleaning blade 21 from the intermediate transfer belt 17 at a predetermined timing (step S1).
Specifically, the control unit 61 drives the drive unit 24 to rotate the blade holder 22 about the support shaft G clockwise when a predetermined timing such as after the end of a job or between images is reached, for example. Then, the tip of the cleaning blade 21 is separated from the intermediate transfer belt 17 (see FIG. 4).
As a result, as shown in FIG. 6, a gap is formed between the tip of the cleaning blade 21 and the intermediate transfer belt 17, and a toner band 300 of the stored toner stored in the storage space 35 is formed on the intermediate transfer belt 17. The Rukoto.

  Next, when the toner band 300 reaches the detection area of the toner adhesion amount detection unit 40 as the intermediate transfer belt 17 rotates, the toner adhesion amount detection unit 40 causes the toner adhesion to the toner band 300. The amount is detected (step S2).

  Next, the control unit 61 determines whether or not the adhesion amount of the toner band 300 has reached a predetermined amount set in advance (step S3), and determines that it has not reached the predetermined amount (step S3: NO). Then, the process proceeds to step S9 described later.

On the other hand, when it is determined that the adhesion amount of the toner band is equal to or larger than the predetermined amount (step S3: YES), the control unit 61 has a predetermined charge amount from the toner band 300 on the intermediate transfer belt 17 in the primary transfer unit. The toner is separated and removed (step S4).
Specifically, the controller 61 controls the primary transfer roller 15K by the bias application unit 15d at the timing when the toner band 300 reaches the primary transfer unit (here, the primary transfer roller 15K) as the intermediate transfer belt 17 rotates. A bias having a polarity opposite to that during normal transfer is applied.
At this time, the current applied to the primary transfer roller 15K is desirably a low current of about several μA to 10 μA, for example.
At this time, the control unit 61 controls the drive units m1, m2, and m3 to separate the primary transfer rollers 15Y, 15M, and 15C from the intermediate transfer belt 17.
As a result, in the toner band 300, a toner that is kept in a favorable charged state (a toner having a predetermined charge amount) is transferred to the primary transfer roller 15K by the electric field. It remains on the intermediate transfer belt 17.

Next, before the toner band 300 on the intermediate transfer belt 17 reaches the secondary transfer roller pair 18, the control unit 61 preferably at a timing immediately before the toner band 300 reaches the secondary transfer roller pair 18. The resistance of the secondary transfer roller pair 18 is detected (step S5).
Specifically, the control unit 61 applies a constant current to the secondary transfer roller pair 18 by the measurement unit 18A before the toner band 300 on the intermediate transfer belt 17 reaches the secondary transfer roller pair 18. The resistance value of the secondary transfer roller pair 18 is measured by detecting the feedback voltage at that time.

Next, the controller 61 detects the resistance of the secondary transfer roller pair 18 at the timing when the toner band 300 is sandwiched between the nip portions of the secondary transfer roller pair 18 (step S6).
Specifically, the control unit 61 applies a constant current to the secondary transfer roller pair 18 by the measurement unit 18A at the timing when the toner band 300 is sandwiched between the nip portions of the secondary transfer roller pair 18, and at that time, , The resistance value of the secondary transfer roller pair 18 is measured.

Next, the control part 61 performs the calculation which correct | amends the value of said step S6 with the value of said step S5 as a calculating part (step S7).
Specifically, the control unit 61 performs an operation for calculating a difference or a ratio between the two values.
The resistance value of the nip portion of the secondary transfer roller pair 18 changes due to production variations (tolerances), energization deterioration, and environmental fluctuations, but the accuracy of the detected value can be improved by performing the calculation in step S7. it can.

Next, the control unit 61 determines whether or not the calculated value is within a preset threshold value (step S8) as a result of the calculation in step S7. If the calculated value is within the preset threshold value (step S8) : YES), this process is terminated.
Note that the threshold used for the determination in step S8 is preferably changed according to the absolute humidity value in the apparatus. Specifically, when the absolute humidity value is high, it is desirable to lower the threshold value. This is because the paper powder contained in the deteriorated toner and the resistance value of the toner having a reduced charge amount vary depending on the amount of water.

  On the other hand, when the preset threshold value is exceeded (step S8: NO), the control unit 61 creates a toner supply band, supplies new toner to the storage unit 30 (step S9), and performs this process. finish.

The processing of step S5 to step S9 is performed in view of the fact that the toner band 300 after the normally charged toner is removed is difficult to accurately measure the quantity and quality by a sensor such as an IDC sensor. Processing.
That is, the control unit 61 determines that the toner stored in the storage unit 30 has deteriorated when the value calculated in step S7 exceeds a preset threshold value, and creates a toner supply band. Then, new toner is supplied to the storage unit 30. Thereby, the toner stored in the storage unit 30 can be replaced.

The length of the toner band 300 used for the toner supply process is preferably equal to or longer than the circumference of the secondary transfer roller pair 18. The length of the toner band 300 can be adjusted by the time for separating the tip of the cleaning blade 21 from the intermediate transfer belt 17.
By setting the length of the toner band 300 in this way, even when the resistance value of the secondary transfer roller pair 18 is uneven when detecting the value of step S6, the accuracy of the detected value is obtained by using the average value. It is because it becomes possible to improve.

In addition, as a timing for performing the toner supply process, an image is formed by selecting a condition in which foreign matters such as paper dust easily enter the cleaning unit 20, for example, a paper type with a lot of paper dust such as plain paper or recycled paper. In such cases, it is desirable to increase the detection frequency.
Further, since the deteriorated toner is likely to be generated when the printing rate is low, it is desirable to adjust the detection frequency based on the printing rate history.

As described above, according to the present embodiment, the toner images formed on the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11K are transferred to the intermediate transfer belt 17, and the toner images transferred to the intermediate transfer belt 17 are transferred. In the image forming apparatus 100 that secondarily transfers the toner onto the paper P, the cleaning blade 21 that contacts the intermediate transfer belt 17 and removes the toner remaining on the intermediate transfer belt 17 after the secondary transfer is removed by the cleaning blade 21. A predetermined charge amount is obtained from a storage unit 30 that stores toner, a toner band forming unit that forms a toner band from the toner stored in the storage unit 30 on the intermediate transfer belt 17, and a toner band on the intermediate transfer belt 17. A toner separation / removal unit for separating and removing toner, a resistance detection unit for detecting the resistance of the toner band after passing through the toner separation / removal unit, and a resistance detection unit In accordance with the detection result, and a toner supply unit for supplying new toner to the reservoir 30.
Therefore, the quality of the stored toner supplied from the storage unit 30 to the intermediate transfer belt 17 can be detected, and new toner can be supplied according to the detection result, so that the quality of the stored toner can be kept constant.
Therefore, it is possible to prevent a situation in which the amount of foreign matter in the toner stored in the storage unit 30 is reduced and foreign matter is caught in the cleaning blade 21 to cause cleaning failure. In addition, it is possible to prevent a situation in which a defective cleaning is caused by a decrease in the amount of deteriorated toner mixed in the toner stored in the storage unit 30 and no external additive being supplied to the cleaning blade 21.

Further, according to the present embodiment, the cleaning blade 21 can be brought into contact with and separated from the intermediate transfer belt 17, and the reservoir 30 is located upstream of the cleaning blade 21 in the rotational direction of the intermediate transfer belt 17. The storage roller 31 that rotates in contact with the intermediate transfer belt 17, the storage sheet 32 that contacts the surface of the storage roller 31, and the storage space 35 formed by the intermediate transfer belt 17 store the toner removed by the cleaning blade 21. The control unit 61 forms the toner band 300 on the intermediate transfer belt 17 by separating the cleaning blade 21 from the intermediate transfer belt 17.
Therefore, the toner band 300 can be formed on the intermediate transfer belt 17 only by operating the cleaning blade 21.

Further, according to the present embodiment, the toner separation and removal unit includes a primary transfer unit that transfers the toner images formed on the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11K to the intermediate transfer belt 17, and a primary transfer unit. Bias application units 15a, 15b, 15c, and 15d that apply a bias having a polarity opposite to that at the time of transferring the toner image to the intermediate transfer belt 17 at the timing when the toner band 300 arrives at Have
For this reason, it is not necessary to provide a new member as the toner separation and removal unit, and the configuration can be simplified.

Further, according to the present embodiment, the resistance detection unit passes the toner image transferred to the intermediate transfer belt 17 to the paper P, and the secondary transfer unit passes the toner separation and removal unit to the secondary transfer unit. A measurement unit 18A that applies a constant current to the secondary transfer unit and measures the value of the feedback voltage at the timing when the subsequent toner band arrives.
For this reason, it is not necessary to provide a new member as the resistance detection unit, and the configuration can be simplified.

Further, according to the present embodiment, the control unit 61 determines the value measured when the secondary transfer unit sandwiches the toner band 300, and the secondary transfer unit is formed with the toner band 300 of the paper P. Compensate with the value measured while holding the non-existing part.
For this reason, the precision of a detected value can be improved.

Further, according to the present embodiment, the secondary transfer unit includes the secondary transfer roller pair 18, the toner band has a length equal to or longer than the circumference of the secondary transfer roller pair 18, and the control unit 61. Measures the distance equal to or greater than the circumference of the secondary transfer roller pair 18 when measuring the value of the feedback voltage of the toner band.
For this reason, even if the measurement value is uneven, the accuracy of the detection value can be improved by using the average value.

Further, according to the present embodiment, the control unit 61 supplies new toner to the storage unit 30 when the detection result of the resistance detection unit exceeds a predetermined threshold, and image formation is performed. The threshold value is changed according to the absolute humidity value in the apparatus 100.
For this reason, it is possible to cope with the case where the resistance value of the paper powder included in the deteriorated toner or the resistance value of the toner whose charge amount has decreased varies depending on the moisture amount.

In addition, according to the present embodiment, the toner adhesion amount detection unit 40 that detects the toner adhesion amount with respect to the toner band 300 on the intermediate transfer belt 17 before reaching the toner separation and removal unit is provided, and the control unit 61 includes When the toner adhesion amount detected by the toner adhesion amount detection unit 40 is less than a predetermined amount, new toner is supplied to the storage unit 30 (a toner supply zone is created).
For this reason, when the toner adhesion amount of the toner band is less than the predetermined amount, it is determined that the toner storage amount of the storage unit 30 is small and new toner is supplied to the storage unit 30. The amount of 30 stored can be kept constant.

Further, according to the present embodiment, the control unit 61 selects the toner band when a preset paper type that generates a large amount of paper dust is selected, or when images with a low printing rate are continuously formed. Increase the frequency of formation.
For this reason, it is possible to more accurately prevent the quality of the toner stored in the storage unit 30 from being lowered.

  The embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be appropriately changed without departing from the spirit of the present invention.

For example, in the above-described embodiment, the configuration in which the toner is separated only at the nip portion of the primary transfer roller 15K has been described as an example. However, the toner may be separated at the nip portion of the primary transfer roller other than this, The toner may be separated at two or more nip portions of the primary transfer rollers 15Y, 15M, 15C, and 15K.
In this case, the control unit 61 can also apply a reverse polarity bias to each nip portion with different output values. For example, when the current value is gradually lowered as it goes downstream in the circumferential direction of the intermediate transfer belt 17, an improvement in toner separation accuracy can be expected.

  In the above embodiment, a configuration is shown in which a constant current is applied to the secondary transfer portion and the value of the feedback voltage is measured. However, a constant voltage is applied to the secondary transfer portion. It may be configured to apply and measure the value of the feedback current.

In the above embodiment, the configuration using the primary transfer unit and the bias application units 15a, 15b, 15c, and 15d as the toner separation / removal unit has been described as an example. However, the toner separation / removal unit is referred to as the primary transfer unit. It can also be set as the structure provided separately.
In this case, as the toner separation / removal unit, for example, a roller pair having the same configuration as that of the primary transfer unit may be provided between the toner adhesion amount detection unit 40 and the primary transfer roller 15Y.

In the above embodiment, the configuration using the secondary transfer unit and the measurement unit 18A as the resistance detection unit has been described as an example. However, the resistance detection unit is configured to be provided separately from the secondary transfer unit. You can also.
In this case, as the resistance detection unit, for example, a roller pair similar to the secondary transfer unit may be provided between the primary transfer roller 15K and the secondary transfer roller pair 18.

  Further, in the above-described embodiment, the configuration in which toner is supplied to the storage unit 30 by creating a toner supply band has been described as an example. However, for example, a separate toner is provided near the storage unit 30. A configuration in which a supply unit is provided and new toner is supplied to the storage unit 30 from the supply unit may be used.

10 Image forming units 11Y, 11M, 11C, 11K Photosensitive drum (photosensitive member)
15Y, 15M, 15C, 15K Primary transfer roller (primary transfer unit, toner separation / removal unit)
15a, 15b, 15c, 15d Bias application unit (toner separation / removal unit)
m1, m2, m3, m4 Drive unit 17 Intermediate transfer belt (image carrier)
18 Secondary transfer roller pair (secondary transfer part, resistance detection part)
18A Measurement unit (resistance detection unit)
20 Cleaning part 21 Cleaning blade (cleaning member)
22 Blade holder 23 Press spring 24 Drive unit 30 Storage unit 31 Storage roller 32 Storage sheet (regulating member)
33 holding member 34 scattering prevention sheet 35 storage space 40 toner adhesion amount detection unit 50 paper feeding unit 61 control unit (toner band forming unit, toner supply unit, calculation unit)
62 Operation unit 63 Display unit 64 Storage unit 65 Communication unit 100 Image forming apparatus 200 Cleaning mechanism 300 Toner belt P Paper

Claims (10)

In an image forming apparatus that primarily transfers a toner image formed on the surface of a photosensitive member to an image carrier, and secondarily transfers the toner image on the image carrier to a transfer member.
A cleaning member that contacts the image carrier and removes toner remaining on the image carrier after secondary transfer;
A reservoir for storing toner removed by the cleaning member;
A toner band forming unit that forms a toner band of toner stored in the storage unit on the image carrier;
A toner separation / removal unit that separates and removes toner having a predetermined charge amount from the toner band on the image carrier;
A resistance detection unit for detecting the resistance of the toner band after passing through the toner separation and removal unit;
A toner supply unit that supplies new toner to the storage unit according to a detection result of the resistance detection unit;
An image forming apparatus comprising: The cleaning member can be brought into contact with and separated from the image carrier,
The storage section includes a roller member that rotates in contact with the image carrier on the upstream side of the cleaning member as viewed in the rotation direction of the image carrier, a regulating member that contacts a surface of the roller member, and the image carrier The toner removed by the cleaning member is stored in a storage space formed by
The image forming apparatus according to claim 1, wherein the toner band forming unit forms the toner band on the image carrier by separating the cleaning member from the image carrier. The toner separation and removal unit
A primary transfer portion for primarily transferring a toner image formed on the surface of the photoreceptor to the image carrier;
At the timing when the toner band formed by the toner band forming unit reaches the primary transfer unit, a bias having a polarity opposite to that at the time of transferring the toner image to the image carrier is applied to the primary transfer unit. A bias applying unit to be applied;
The image forming apparatus according to claim 1, further comprising: The primary transfer unit includes a plurality of primary transfer rollers,
The image forming apparatus according to claim 3, wherein the bias applying unit applies reverse polarity biases with different output values to the plurality of primary transfer rollers. The resistance detector
A secondary transfer unit for secondary transfer of the toner image primarily transferred to the image carrier to the transfer target;
A constant current or voltage is applied to the secondary transfer unit at a timing when the toner band after passing through the toner separation and removal unit reaches the secondary transfer unit, and a feedback voltage or a value of the feedback current is set. A measuring section to measure,
The image forming apparatus according to claim 1, further comprising: The resistance detector
The value measured when the secondary transfer part is sandwiching the toner band, the value measured when the secondary transfer part is sandwiching a portion of the transfer body where the toner band is not formed The image forming apparatus according to claim 5, further comprising: a calculation unit that corrects the image by the correction. The secondary transfer unit includes a secondary transfer roller,
The toner band has a length equal to or greater than a circumference of the secondary transfer roller;
7. The measurement unit according to claim 5, wherein the measurement unit measures a distance equal to or greater than a circumference of the secondary transfer roller when the secondary transfer unit holds the toner band. 8. Image forming apparatus. When the detection result of the resistance detection unit exceeds a predetermined threshold, the toner supply unit supplies new toner to the storage unit,
The image forming apparatus according to claim 1, wherein the threshold value is changed according to an absolute humidity value in the image forming apparatus. A toner adhesion amount detection unit that detects a toner adhesion amount with respect to the toner band on the image carrier before reaching the toner separation and removal unit;
9. The toner supply unit according to claim 1, wherein when the toner adhesion amount detected by the toner adhesion amount detection unit is less than a predetermined amount, new toner is supplied to the storage unit. The image forming apparatus according to one item.   The toner band forming unit increases the frequency of forming the toner band when a preset paper type that generates a large amount of paper dust is selected or when images with a low printing rate are continuously formed. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.

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