JP6965633B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus.

The electrophotographic image forming apparatus forms optical image information on a uniformly charged image carrier, and the obtained charged latent image is visualized by toner from the developing apparatus. Then, an image is formed by transferring and fixing this visible image on a recording paper (recording material). As an image forming apparatus of this kind, for example, Patent Document 1 is known.

The image forming apparatus of Patent Document 1 forms a toner image on the surface of a drum-shaped photoconductor by a well-known electrophotographic process. An endless intermediate transfer belt is brought into contact with the photoconductor to form a primary transfer nip. Then, at the primary transfer nip, the toner image on the photoconductor is first transferred to the intermediate transfer belt. A secondary transfer roller as a nip forming member is brought into contact with the intermediate transfer belt to form a secondary transfer nip. Further, a secondary transfer opposed roller is arranged in the loop of the intermediate transfer belt, and the intermediate transfer belt is sandwiched between the secondary transfer opposed roller and the above-mentioned secondary transfer roller.

A secondary transfer bias is applied to the secondary transfer roller on the outside of the loop, while the secondary transfer opposed roller on the inside of the loop is connected (grounded) to the ground. As a result, a secondary transfer electric field is formed between the secondary transfer opposed roller and the secondary transfer roller to electrostatically move the toner image from the former side to the latter side. Then, the toner image on the intermediate transfer belt is secondarily transferred to the recording paper fed into the secondary transfer nip at the timing synchronized with the toner image on the intermediate transfer belt by the action of the secondary transfer electric field.

The transfer residual toner remaining on the intermediate transfer belt is removed by a cleaning blade (cleaning device) pressed against the intermediate transfer belt.

An object of the present invention is to provide an image forming apparatus capable of improving the heating efficiency of a cleaning member and suppressing a decrease in cleaning function.

The above-mentioned problems are a carrier for transporting a recording material, a cleaning member for cleaning the carrier, a heater, an image carrier for carrying a toner image, and a moving mechanism for moving the cleaning member and / or the heater. The moving mechanism brings the cleaning member closer to the heater and the heater at a predetermined timing other than when the toner image is formed on the recording material. In the image forming apparatus that generates heat, the moving mechanism is solved by an image forming apparatus that also serves as a contacting / separating mechanism that brings the carrier and the image carrier into contact with each other and separates the image carrier.

The subject also includes an image carrier that supports a toner image, a cleaning member that cleans the image carrier, a heater, a photoconductor, and a moving mechanism that moves the cleaning member and / or the heater. At a predetermined timing other than when the toner image is formed on the image carrier, the moving mechanism brings the cleaning member closer to the heater as compared with when the toner image is formed on the image carrier. In the image forming apparatus for generating heat of the heater, the image supporting body is also solved by an image forming apparatus characterized in that it is an intermediate transfer body that abuts on the photoconductor to form a transfer nip.

In the image forming apparatus of the present invention, the distance between the cleaning member and the heater is made closer and the heater is moved at a predetermined timing other than when the toner image is formed on the recording material or the like as compared with the time when the toner image is formed on the recording material or the like. Make it generate heat. Therefore, it is possible to improve the heating efficiency of the cleaning member and suppress the deterioration of the cleaning function.

It is a graph which shows the relationship between the ambient temperature in a cleaning blade, and the amount of toner passing through. It is a schematic block diagram of the image forming apparatus which concerns on one Embodiment of this invention. It is an external view of the secondary transfer apparatus which concerns on one Embodiment of this invention as seen from obliquely above. It is an external view which looked at the secondary transfer apparatus and the contact / separation cam mechanism which concerns on one Embodiment of this invention from obliquely above. It is an external view of the secondary transfer apparatus and the contact / detachment cam mechanism which concerns on one Embodiment of this invention as seen from the side. It is a schematic diagram which shows the state of the secondary transfer unit at the time of image formation. It is a schematic diagram which shows the state of the secondary transfer unit except at the time of image formation. It is a schematic diagram which shows the internal structure of the heater unit which concerns on one Embodiment of this invention. It is a flowchart explaining the heater lighting / extinguishing state of the image forming apparatus which concerns on embodiment.

Hereinafter, before the embodiment is described, preliminary matters for facilitating the understanding of the embodiment will be described.

A rubber member is used for the cleaning blade that removes residual toner during transfer, and it is known that the cleaning function deteriorates due to wear over time. Especially in a low temperature environment, it is also known that the deterioration of the rubber function causes minute toner slip-through and promotes wear of the blade edge.

FIG. 1 is a graph showing the relationship between the ambient temperature of the cleaning blade and the amount of toner slipping through. The horizontal axis is the ambient temperature (degrees), and the vertical axis is the amount of toner slipping through. Cluff shows two types of cleaning blades that have gone through different sheets of paper.

As can be seen from FIG. 1, the lower the ambient temperature, the larger the amount of toner slipping through. This is because the function of the rubber used for the blade is reduced. Further, the larger the number of sheets to be passed (the more the paper is used over time), the larger the amount of toner slipping through. As described above, the cleaning blade has accelerated wear of the blade edge, especially in a low temperature environment, and the cleaning function is deteriorated due to wear over time.

As a remedy for this phenomenon (problem), a method of heating the cleaning blade with a heater or the like to improve the rubber function is known. However, in a low temperature state immediately after startup, it takes time for the cleaning blade to reach a sufficient temperature, and there is a problem that the cleaning blade is used before obtaining a desired rubber function.

In the following embodiment, an image forming apparatus capable of improving the heating efficiency of the cleaning member and suppressing the deterioration of the cleaning function will be described.

(Embodiment)
FIG. 2 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. In the present embodiment, the same functions and the same configurations are designated by the same reference numerals, and duplicate description will be omitted as appropriate. Drawings may be partially omitted to aid in understanding some configurations. In the figure, Y, M, C, and K are subscripts attached to the constituent members corresponding to yellow, magenta, cyan, and black, and are omitted as appropriate.

As shown in FIG. 2, the electrophotographic color printer (hereinafter referred to as “printer”) 100, which is an image forming apparatus, has yellow (Y), magenta (M), cyan (C), and black (K) toners. It includes four image forming units 1Y, 1M, 1C, and 1K that form an image. Further, the printer 100 includes an intermediate transfer unit 30 as an intermediate transfer device, a belt-type secondary transfer device 40, a cassette 60 for accommodating an object to be transported, a fixing device 90, a power supply device, and the like.

The four image forming units 1Y, 1M, 1C, and 1K, which serve as image forming portions, are powders and use toners of different colors Y, M, C, and K as developing agents, but have the same configuration other than that. Is. The image forming units 1Y, 1M, 1C, and 1K are drum-shaped photoconductors 2Y, 2M, 2C, and 2K that are image carriers, drum cleaning devices 3Y, 3M, 3C, 3K, a static eliminator, and a charging device 6Y. , 6M, 6C, 6K and developing devices 8Y, 8M, 8C, 8K and the like. The image forming units 1Y, 1M, 1C, and 1K form a process cartridge unit in which these plurality of devices are held in a common holder and can be integrally attached to and detached from the printer 100. That is, these four image forming units 1Y, 1M, 1C, and 1K can be exchanged in units of units, and can be exchanged, for example, when the service life is reached.

The photoconductors 2Y, 2M, 2C, and 2K are rotationally driven in the counterclockwise direction in the drawing by a driving means such as a motor. In the charging devices 6Y, 6M, 6C, and 6K, the charging roller and the photoconductor 2Y, 2M, 2C are brought into contact with or close to the photoconductors 2Y, 2M, 2C, and 2K while the charging roller, which is a charging member to which the charging bias is applied, is brought into contact with or close to the photoconductors 2Y, 2M, 2C, and 2K. A discharge is generated between 2K and 2K. As a result, the surfaces of the photoconductors 2Y, 2M, 2C and 2K are uniformly charged. In addition, instead of the method of bringing a charging member such as a charging roller into contact with or close to the photoconductors 2Y, 2M, 2C, and 2K, a method using a charging charger may be adopted.

The surfaces of the photoconductors 2Y, 2M, 2C, and 2K uniformly charged by the charging devices 6Y, 6M, 6C, and 6K include laser light emitted from the optical writing unit 101 arranged above the image forming unit 1. Light is scanned by the exposure light of the above, and an electrostatic latent image for each color is formed.

This electrostatic latent image is developed by developing devices 8Y, 8M, 8C, and 8K having toners of each color to obtain a toner image T as an image of each color. The toner image T of the photoconductors 2Y, 2M, 2C, and 2K is primarily transferred and supported on the front surface 31a of the intermediate transfer belt 31 made of an endless belt member.

The drum cleaning device 3Y, 3M, 3C, and 3K removes the transfer residual toner adhering to the surfaces of the photoconductors 2Y, 2M, 2C, and 2K after undergoing the primary transfer step (primary transfer nip N1 described later). The static eliminator removes residual charges of the photoconductors 2Y, 2M, 2C, and 2K after being cleaned by the drum cleaning device 3Y, 3M, 3C, and 3K. The surfaces of the photoconductors 2Y, 2M, 2C, and 2K are initialized by this static elimination to prepare for the next image formation.

(Intermediate transfer unit)
Below the image forming units 1Y, 1M, 1C, and 1K, the intermediate transfer unit is a belt unit that moves (rotates) in the clockwise direction in the figure while the intermediate transfer belt 31 is stretched, and is an intermediate transfer device. 30 is arranged. The intermediate transfer unit 30 is also referred to as a primary transfer unit or a transfer unit. In the present embodiment, the surface moving direction of the intermediate transfer belt 31 is the belt moving direction a (arrow a in the figure).

The intermediate transfer unit 30 is detachable (replaceable) with respect to the printer 100. The intermediate transfer unit 30 includes an intermediate transfer belt 31 which is both a belt-shaped image carrier and an intermediate transfer body. The intermediate transfer unit 30 includes a drive roller 32, a secondary transfer back surface roller 33, a cleaning backup roller 34, four primary transfer rollers 35Y, 35M, 35C, 35K, a pre-transfer roller 37, and the like. Of these, the secondary transfer back surface roller 33 is a nip forming member, which is a pressurized body, and is a repulsive roller, which is arranged inside the loop of the intermediate transfer belt 31, which is a transfer member that moves endlessly.

The intermediate transfer belt 31 is transferred to a drive roller 32 which is a rotating body arranged inside the loop, a secondary transfer back surface roller 33, a cleaning backup roller 34, and primary transfer rollers 35Y, 35M, 35C, 35K. It is wrapped around the front roller 37 and stretched. Then, due to the rotational force of the drive roller 32 that is rotationally driven in the clockwise direction in the drawing by a drive means such as a drive motor, the drive roller 32 is endlessly moved and conveyed in the same direction.

In the present embodiment, the intermediate transfer belt 31 is composed of an endless elastic belt having elasticity in which a plurality of layers are laminated, and the toner image on the photoconductors 2Y, 2M, 2C, and 2K is primarily transferred. ..

The primary transfer rollers 35Y, 35M, 35C, and 35K sandwich the endlessly moved intermediate transfer belt 31 between the photoconductors 2Y, 2M, 2C, and 2K. Then, the front surface 31a forming the image-carrying surface of the intermediate transfer belt 31 and the surfaces of the photoconductors 2Y, 2M, 2C, and 2K are in contact with each other to form the primary transfer nip N1 serving as the primary transfer portion. ..

A primary transfer bias is applied to each of the primary transfer rollers 35Y, 35M, 35C, and 35K from a well-known transfer bias power supply. As a result, a transfer electric field is formed between the toner images of Y, M, C, and K on the photoconductors 2Y, 2M, 2C, and 2K and the primary transfer rollers 35Y, 35M, 35C, and 35K.

The Y toner image formed on the surface of the yellow photoconductor 2Y enters the yellow primary transfer nip N1 as the photoconductor 2Y rotates. Then, by the action of the transfer electric field and the nip pressure, the primary transfer is performed from the photoconductor 2Y onto the intermediate transfer belt 31. The intermediate transfer belt 31 on which the Y toner image is primarily transferred in this way then sequentially passes through the primary transfer nip N1 for M, C, and K. Then, the M, C, and K toner images on the photoconductors 2M, 2C, and 2K are sequentially superimposed on the Y toner image and primary transferred. By this superposition primary transfer, a four-color superposition toner image is formed on the intermediate transfer belt 31.

The image forming steps up to this point have been described on the premise of forming a four-color full-color image. However, the printer 100 may form a single color toner image of any one of yellow, magenta, cyan, and black, or a toner image using at least two colors of the toner, and transfer the toner image to the intermediate transfer belt 31. It is possible.

(Secondary transfer device)
A secondary transfer device 40 including a secondary transfer unit 41, a heater unit 490, and a plurality of cleaning members 407 and 408 is arranged below the outside of the loop of the intermediate transfer belt 31. The secondary transfer unit 41 includes a secondary transfer belt 406 which is a belt member and a transfer member. The secondary transfer belt 406 is also a carrier that conveys the recording material P. The secondary transfer belt 406 is a material harder than the resin intermediate transfer belt 31, and is, for example, a polyimide resin belt (PI belt).

The secondary transfer belt 406 includes a separation roller 401, a driven roller 402, a tension roller 403 constituting the first blade facing roller and the tension applying member, and a second blade facing roller 404, which are a plurality of rotating bodies. It is wound around the next transfer roller 405. Further, the secondary transfer belt 406 is tensioned from the inside to the outside by the tension roller 403. The secondary transfer belt 406 also functions as a drive roller. That is, the secondary transfer belt 406 is configured to rotate and transfer in the counterclockwise direction in the drawing by transmitting the driving force from the drive source to the secondary transfer roller 405.

The secondary transfer unit 41 is mounted on a pressure frame 49 constituting the pressure device 480, and the side plate 49A below the pressure frame 49 is rotatably supported around a support shaft 48. ..

As shown in detail in FIG. 6, the pressurizing device 480 includes pressurizing arms 481A and 481B which are pressurizing structures rotatable around a rotation fulcrum 484. Further, the cams 482A and 482B rotatably supported by the rotation fulcrum 485, the cam followers 483A and 483B, and the drive motor 486 are provided. The cams 482A and 482B are rotated by the drive motor 486 to move the cam followers 483A and 483B provided on the pressurizing arms 481A and 481B. Further, the pressurizing arms 481A and 481B can come into contact with the other end side 49B of the pressurizing frame 49 constituting the pressurizing device 480.

With this configuration, by driving the drive motor 486 clockwise / counterclockwise, the pressurizing arms 481A and 481B urge the force in the direction of pushing up the other end side 49B of the pressurizing frame 49. It can be released.

That is, the pressurizing device 480 supports the secondary transfer unit 41 including the secondary transfer belt 406 so as to be swingable by the support shaft 48, and the pressurizing arm is attached to the other end side 49B located away from the support shaft 48. The 481 is brought into contact. As a result, the secondary transfer unit 41 mounted on the pressure frame 49 is urged toward the intermediate transfer belt 31, and the secondary transfer belt 406 is pressed against the intermediate transfer belt 31.

Returning to FIG. 2, the secondary transfer unit 41 sandwiches the intermediate transfer belt 31 between the secondary transfer back surface roller 33 and the secondary transfer belt 406 arranged inside the loop of the intermediate transfer belt 31. Then, a secondary transfer nip N2 is formed as a transfer portion where the front surface 31a of the intermediate transfer belt 31 and the secondary transfer belt 406 come into contact with each other. In the present embodiment, the secondary transfer bias is applied to the secondary transfer back surface roller 33 by the secondary transfer power supply 39 as the transfer bias output means. As a result, a secondary transfer electric field is formed between the secondary transfer back surface roller 33 and the secondary transfer belt 406, and the toner charged in a negative polarity is transferred from the secondary transfer back surface roller 33 side to the secondary transfer belt 406 side. Electrostatically move toward.

In the present embodiment, the toner image on the intermediate transfer belt 31 is secondarily transferred to the recording material P at the secondary transfer nip N2 serving as the transfer portion. The intermediate transfer belt 31 is an image carrier that forms a secondary transfer nip N2 with the secondary transfer belt 406, which is a transfer belt (conveyor), and is a toner image on the photoconductors 2Y, 2M, 2C, and 2K. Is also an intermediate transcript to which is primarily transcribed. The toner image transferred to the secondary transfer belt 406 is a toner image used for measuring the image density.

Then, the transfer residual toner remaining on the secondary transfer belt 406 is removed by the cleaning members 407 and 408 pressed against the secondary transfer belt 406.

In the present embodiment, the secondary transfer back surface roller 33 is configured to apply a bias (secondary transfer bias) used for the secondary transfer from the secondary transfer power supply 39. Instead of this, a bias may be applied from the secondary transfer power supply 39 to the secondary transfer roller 405 which is arranged to face the secondary transfer back surface roller 33 and constitutes the pressure member. When applying the secondary transfer bias to the secondary transfer roller 405, the secondary transfer bias having the opposite polarity to the toner is applied, and when applying the transfer bias to the secondary transfer back surface roller 33, it is the same as the toner. Apply a polarity bias. The secondary transfer roller 405 is also referred to as a nip forming roller.

(Heater unit)
The heater unit 490 arranged under the secondary transfer device 40 includes a heat generating portion (heater) that generates heat by receiving power supply and a case that covers the heat generating portion. When the main power supply 45 of the apparatus main body is turned on, the heat generating portion of the heater unit 490 is supplied with electric power and starts to generate heat. A capacitor (electric storage device) may be provided inside the printer 100, and power may be supplied to the heat generating portion (heater) by the capacitor. In this case, electric power can be supplied to the heat generating portion (heater) even when the main power supply of the apparatus main body is turned off.

(cassette)
Below the secondary transfer device 40, a cassette 60 that serves as an accommodating portion that can accommodate a plurality of recording materials P in a bundle is arranged. In this cassette 60, the roller 60a is brought into contact with the recording material P at the top of the bundle, and by rotationally driving the roller 60a at a predetermined timing, the recording material P is directed from the cassette 60 to the secondary transfer nip N2. It is sent out toward the transport path 65. The recording material P sent out to the transport path 65 is sent out to the secondary transfer nip N2 by the resist roller pair 61 at the timing synchronized with the toner image on the front surface 31a of the intermediate transfer belt 31 in the secondary transfer nip N2. Is done. The recording material P is one of the objects to be transported.

The toner image of the front surface 31a of the intermediate transfer belt 31 is collectively secondary transferred onto the recording material P by the secondary transfer nip N2 by the action of the secondary transfer electric field and the nip pressure, and is in full color in combination with the white color of the recording material P. It becomes a toner image. The transfer residual toner that has not been transferred to the recording material P is attached to the front surface 31a of the intermediate transfer belt 31 after passing through the secondary transfer nip N2. The transfer residual toner is cleaned from the belt surface by the intermediate belt cleaning device 38 that is in contact with the front surface 31a of the intermediate transfer belt 31.

(Fixing device)
A fixing device 90 is arranged downstream of the secondary transfer nip N2 in the recording material transport direction b. The recording material P on which the toner image is transferred is sent to the fixing device 90. The fed recording material P is sandwiched between the fixing nips in which the fixing roller 91 having a heat source inside and the pressure roller 92 come into contact with each other. Then, the toner in the full-color toner image is softened and fixed by heating and pressurizing. The recording material P after fixing is discharged from the inside of the fixing device 90 and discharged to the outside of the machine.

(Power supply)
The printer 100 is provided with a main power supply 45, which is a breaker, and a power supply switch 46 as power supply devices. When the main power supply 45 is OFF, the printer 100 is not energized and is completely stopped. When the main power supply 45 is ON, the printer 100 is energized. When the main power supply 45 is turned on and the power switch 46 is turned on, the printer 100 is prepared for printing.

(controller)
The printer 100 includes a controller 72 as a control unit connected to the power control unit 70 and the drive motor 486. The controller 72 is also connected to the image forming units 1Y, 1M, 1C, 1K, the secondary transfer power supply 39, and the like to control the formation of the toner image on the recording material. The power control unit 70 controls the power supplied from the main power supply 45 (or the capacitor) to the heater unit 490 based on the control signal output from the controller 72.

The controller 72 uses a moving mechanism (contact / detachment mechanism) to bring the cleaning member closer to the heater at a predetermined timing other than when forming the toner image on the recording material, as compared with when forming the toner image on the recording material. In addition, the power control unit 70 and the drive motor 486 are controlled so as to generate heat at the same time. The moving mechanism (contact / detachment mechanism) will be described later.

Subsequently, the secondary transfer device 40 and the devices around it will be described.

FIG. 3 is an external view of the secondary transfer device according to the embodiment of the present invention as viewed from diagonally above. In FIG. 3, the same objects as those in FIG. 2 are designated by the same reference numerals, and detailed description thereof will be omitted.

The secondary transfer device 40 intermediately transfers the secondary transfer roller 405, which is a nip forming member, over the entire width direction W orthogonal to the belt movement direction a in the front 31 a of the intermediate transfer belt 31 by the pressurizing device 480. Pressurization can be performed toward the belt 31.

As shown in FIG. 3, the pressure frame 49 is provided with a support shaft 48 on the side plate 49A. The pressurizing frame 49 is swingably supported by the side plates 50A and 50B of the pressurizing device holding unit 50 with the support shaft 48 as a fulcrum.

Further, the position of the support shaft 48 can be adjusted. One end 48A of the support shaft 48 extends to the side plate 49A of the pressurizing frame 49 located in the width direction W, and penetrates the side plate 50A of the pressurizing device holding unit 50 located outside the side plate 49A. The end 48A of the penetrating support shaft 48 is rotatably supported by the position adjusting plate 530, which is a position adjusting member.

The position adjusting plate 530 is made of sheet metal and is attached to the side plate 50A of the pressurizing device holding unit 50 with a fastening member. The mounting position is movable because it is composed of elongated holes and the like, and therefore the position of the support shaft 48 is adjustable.

Further, the position adjusting plate 530 is formed with a jig insertion portion 531 for inserting a jig for adjustment. When loosening the fastened state of the position adjusting plate 530 and adjusting the position, the position can be easily adjusted by inserting the jig into the jig insertion portion 531.

Subsequently, the configuration of the contact / detachment cam mechanism that abuts or separates the secondary transfer back surface roller 33 from the secondary transfer roller 405 will be described.

FIG. 4 is an external view of the secondary transfer device and the contact / detachment cam mechanism according to the embodiment of the present invention as viewed from diagonally above, and FIG. 5 shows the secondary transfer device and the contact / detachment cam mechanism according to the embodiment of the present invention. It is an external view which is seen from the side. In FIGS. 4 and 5, the same objects as those in FIGS. 2 and 3 are designated by the same reference numerals, and detailed description thereof will be omitted.

The contact / detachment cam mechanism 470 includes the contact / detachment cams 471A and 471B, the rotary rollers 472A and 472B that come into contact with the contact / detachment cams 471A and 471B, and the contact / detachment motor 473 as a drive source for rotationally driving the contact / detachment cams 471A and 471B. To be equipped. Here, the contact / detachment cams 471A and 471B are provided at both ends of the shaft 33A of the secondary transfer back surface roller 33, and the rotary rollers 472A and 472B are provided at both ends of the shaft 405A of the secondary transfer roller 405.

The contact / detachment cams 471A and 471B are eccentric cams formed on the same cam profile, and are fixed to both ends of the shaft 33A at the same angle (phase). In the contact / detachment cams 471A and 471B, the position where the distance between the contact / detachment cams 471A and 471B and the shaft 33A is the longest is set as the top dead center, and the position where the distance between the contact / detachment cams 471A and 471B and the shaft 33A is the shortest is below. It is a dead center.

A pulley 474 is provided at the end of the shaft 33A located outside the contact / detachment cam 471A in the axial direction. A drive belt 476 is wound around the pulley 474 with a drive pulley 475 provided on the drive shaft 473a of the contact / detachment motor 473. A cam position sensor 477 as a cam position detecting means for detecting the positions of the contact / detachment cams 471A and 471B by detecting the rotation angle of the pulley 474 is arranged around the pulley 474.

The operation of the contact / detachment cam mechanism 470 will be described. When the contact / detachment motor 473 operates, the rotational driving force of the contact / detachment motor 473 is transmitted to the shaft 33A via the drive pulley 475, the drive belt 476, and the pulley 474. Then, the distance between the shaft 33A and the shaft 405A changes as the contact / detachment cams 471A and 471B fixed to both ends of the shaft 33A rotate.

When the contact / detachment cams 471A and 471B and the shaft 33A are separated from each other (top dead center), the secondary transfer back surface roller 33 and the secondary transfer roller 405 are separated from each other. On the other hand, when the contact / detachment cams 471A and 471B and the shaft 33A come close to each other (bottom dead center), the secondary transfer back surface roller 33 and the secondary transfer roller 405 come into contact with each other. The rotation angles (rotation positions) of the contact / detachment cams 471A and 471B are detected by the cam position sensor 477.

The contact / disengagement operation by the contact / disengagement cam mechanism 470 is executed within a short time between the recording material P to be conveyed and the next recording material P. That is, at the time of printing in which the toner image is transferred to the recording material P, the contact / detachment motor 473 is operated so as to press the rotary rollers 472A and 472B at the top dead center of the contact / detachment cams 471A and 471B, respectively. Then, the contact / detachment motor 473 is operated so that the bottom dead center of the contact / detachment cams 471A and 471B comes into contact with the rotary rollers 472A and 472B between the recording material P and the next recording material P, so-called paper. Therefore, it is preferable to use a stepping motor, which is a responsive motor, as the contact / detachment motor 473 for the contact / detachment operation of the secondary transfer unit 41.

Subsequently, a characteristic part of the present invention will be described.

As shown in FIG. 2, the cleaning members 407 and 408 provided in the secondary transfer unit 41 are cleaning blades, and it is known that the cleaning property is deteriorated in a low temperature environment. In the present embodiment, a heater unit 490 for heating the cleaning members 407 and 408 is provided in the vicinity of the cleaning members 407 and 408.

However, when the temperature including the main body device is low, for example, immediately after the main power is turned on, there is a problem that it takes time for the cleaning blade to reach a sufficient temperature. Further, since the cleaning blade is generally heated by the heat generated when the image forming apparatus is driven, a sufficient rubber function can be obtained from a certain point in time. On the other hand, when the image forming apparatus is not driven, the temperature of the main body apparatus decreases and the temperature of the cleaning blade also decreases.

From these facts, it is desirable to bring the cleaning blade to a sufficient temperature as soon as possible from the time when the main power is turned on, and to prevent the temperature of the cleaning blade from dropping in the non-driving state (stopped state, standby state). I can say.

Therefore, in the present embodiment, at a predetermined timing other than when the toner image is formed on the recording material, the distance between the cleaning member and the heater is made closer than when the toner image is formed on the recording material, and the heater is heated. Use the configuration. As a result, the heating efficiency of the cleaning members 407 and 408 can be improved, and the cleaning property can be maintained.

Here, the above-mentioned "predetermined timing other than when forming a toner image on a recording material" is a state in which an image is not formed (other than when an image is formed), and is a timing in which the device main body is in a stopped state or a standby state. Means that it is in. The "stopped state" is a state in which the main body of the device is energized (the main power supply 45 is ON), but the power switch 46 is OFF. The "standby state" is a state in which a part of the function is stopped for the purpose of reducing power consumption when the device main body is not operated for a certain period of time. The image forming apparatus in the standby state can shift to the driving state (the state in which image formation is possible) in a short time.

FIG. 6 is a schematic diagram showing the state of the secondary transfer unit at the time of image formation, and FIG. 7 is a schematic diagram showing the state of the secondary transfer unit at the time other than the time of image formation. In FIGS. 6 and 7, the same objects as those in FIGS. 2 to 5 are designated by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 6, at the time of image formation, the intermediate transfer belt 31 and the secondary transfer belt 406 are brought into contact with each other (pressure contact state) by the contact / detachment cam mechanism 470. Further, the pressurizing device 480 urges the secondary transfer unit 41 to push it upward. The contact state here is a pressurized state in which a nip pressure at which a toner image can be transferred is generated on the recording material P.

At the time of image formation (that is, when forming a toner image on the image carrier), the temperature of the cleaning members 407 and 408 is set to a temperature at which a sufficient rubber function can be obtained due to the heat generated when various devices are driven. Is kept in. Therefore, at the time of image formation, the heat generation of the heater unit 490 is stopped.

On the other hand, as shown in FIG. 7, the intermediate transfer belt 31 and the secondary transfer belt 406 are separated from each other by the contact / detachment cam mechanism 470 except when the image is formed. Further, the urging force of the pressurizing device 480 is lost, and the secondary transfer unit 41 is pushed downward. In the present embodiment, the heater unit 490 is turned on except when this image is formed. At the same time, the cleaning members 407 and 408 are moved downward along with the secondary transfer unit 41 to approach the heater unit 490.

As described above, the temperature of the cleaning members 407 and 408 can be efficiently raised by bringing the cleaning members 407 and 408 closer to the lit heater unit 490 except when the image is formed. Further, the secondary transfer belt 406 can also approach the heater unit 490 and heat its surface. In this case, it is possible to prevent the heat of the cleaning members 407 and 408 from escaping to the secondary transfer belt 406, so that the heating efficiency can be further improved.

When the image is formed again, the state shown in FIG. 7 shifts to the state shown in FIG. As the secondary transfer unit 41 separates from the heater unit 490, the cleaning members 407 and 408 also move away from the heater unit 490. As a result, it is possible to prevent the cleaning members 407 and 408 from being heated more than necessary due to the heat of the heater unit 490 or the heat remaining near the heater unit 490.

In the present embodiment, the contact / detachment cam mechanism 470 and the pressurizing device 480 are moving mechanisms for moving the cleaning members 407 and 408 to the heater unit 490. That is, the contact / disengagement cam mechanism 470 and the pressurizing device 480 are not only a moving mechanism but also a contact / disengagement mechanism for contacting and separating the carrier and the image carrier. This configuration is advantageous because the movement and attachment / detachment mechanism can be implemented at no cost.

Instead of this configuration, a moving mechanism (for example, a cylinder or the like) for moving the cleaning members 407 and 408 may be provided so as to move (approach or separate) the heater unit 490. Further, the heater unit 490 may be provided with a moving mechanism, and the heater unit 490 may be moved with respect to the cleaning members 407 and 408, or both the cleaning members 407 and 408 and the heater unit 490 may be provided with a moving mechanism.

The present invention is also effective in a configuration in which the cleaning members 407, 408 and / or the secondary transfer belt 406 are arranged in the exterior (cover) of the secondary transfer unit 41. By bringing the secondary transfer unit 41 itself closer to the heater unit 490, which is the heating source, the temperature around the secondary transfer unit 41 rises faster. Therefore, the cleaning members 407, 408 and / or the secondary transfer belt 406 can be efficiently heated.

FIG. 8 is a schematic view showing the internal structure of the heater unit according to the embodiment of the present invention. An advantageous configuration of the heater unit 490 will be described with reference to FIG.

The heating unit 82 of the heater unit 490 is a "heater" and has a heating wire. The heat generating unit 82 generates heat by the electric power supplied from the power source via the power control unit 70. The amount of electric power supplied, that is, the amount of heat generated by the heater is controlled by the controller 72 (see FIG. 2). The power supply (power control unit 70) and the heat generating unit 82 are electrically connected by a harness 86. A thermostat 84, which is an automatic temperature control device, is provided in the middle of the path of the harness 86. The heat generating portion 82, the thermostat 84, and the like are housed in the case 88. For convenience of explanation, the case 88 shows only the back side portion of the heat generating portion 82. The actual case 88 is also provided on the front side of the heat generating portion 82, and covers the entire heat generating portion 82.

With this configuration, the heat generating unit 82 of the heater unit 490 generates heat when power is supplied, but when the temperature of the heat generating unit 82 reaches a predetermined temperature, the power supply is cut off by the thermostat 84. .. Therefore, the heater unit 490 can prevent the cleaning members 407 and 408 from being heated more than necessary even if the state other than the time of image formation continues for a long time. The thermostat 84 of the present embodiment is set to shut off the power supply when the temperature of the heat generating portion reaches about 40 degrees.

Instead of the thermostat 84, a device provided with a sensor and a controller and controlling ON / OFF of the power supply according to the detection temperature of the sensor may be used as the automatic temperature control device.

Subsequently, the heater on / off state of the image forming apparatus (printer 100) according to the present embodiment will be described with reference to the flowchart of FIG.

First, when the main power supply 45 of the printer 100 is turned on (S1), the heater unit 490 lights up (S2). As a result, the cleaning members 407 and 408 are heated by the heater unit 490. Next, when the power switch 46 is turned on (S3), the heater unit 490 is turned off (S4), and the intermediate transfer belt 31 and the secondary transfer belt 406 are in contact with each other (S5). From this, the printer 100 can print.

Next, in step S6, when the power switch 46 is turned off, the intermediate transfer belt 31 and the secondary transfer belt 406 are separated from each other (S7), and the printer 100 is stopped (S8). Then, the heater unit 490 lights up (S9).

On the other hand, in step S6, if the power switch 46 is ON, the process proceeds to step S10. When the printer 100 is not operated (not operated) for a predetermined time, the intermediate transfer belt 31 and the secondary transfer belt 406 are separated from each other (S11), and the printer 100 is put into a standby state (S12). Then, the heater unit 490 lights up (S9). If the printer 100 is operated (operated) in step S10, the process returns to step S4.

In this way, the heater unit 490 lights up when (a) the main power supply 45 is turned on, and (b) the printer 100 is in the stopped state or the standby state. Further, as the intermediate transfer belt 31 and the secondary transfer belt 406 are separated from each other, the cleaning members 407 and 408 approach the heater unit 490.

(Modification example)
In the above embodiment, an example applied to the secondary transfer device 40 of the secondary transfer belt type of the image forming apparatus that forms a color image as a belt-shaped carrier has been described, but the application of the belt-shaped carrier is applicable. It is not limited to the secondary transfer device 40. For example, an image forming apparatus for forming a monochrome image is a transfer device, which abuts on an image carrier and an image carrier to form a transfer portion between the two, and conveys a recording material to the transfer portion to convey a toner image. It can also be applied to a transfer device of a direct transfer method that directly transfers the image to a recording material. Further, it can be applied to a roller-shaped carrier instead of the belt-shaped carrier.

In the above embodiment, the image forming apparatus has been described by using a transfer unit (secondary transfer nip N2) for transporting the recording material P in the horizontal direction, but the present invention is not limited to this. The present invention can also be applied to an image forming apparatus having a structure in which a recording material P is conveyed upward, downward, diagonally upward, diagonally downward, or the like at a transfer unit.

Further, a photoconductor that is an image carrier that supports toner, a cleaning member that cleans the photoconductor, a heater that heats the cleaning member, and a moving mechanism (contact / detachment mechanism) that brings the photoconductor and the heater closer to each other or separated from each other are provided. It can also be applied to an image forming apparatus provided. Furthermore, the same can be applied to an image forming apparatus including an intermediate transfer body which is an image carrier that abuts on a photoconductor to form a transfer nip. In these configurations, the distance between the cleaning member and the heater is brought closer and the heater is heated at a predetermined timing other than when the toner image is formed on the image carrier. Further, when the toner image is formed on the image carrier, the heat generation of the heater is stopped.

That is, even in these configurations, the heating efficiency of the cleaning member can be improved and the deterioration of the cleaning function can be suppressed by bringing the cleaning member close to the lit heater except when the image is formed.

In the above embodiment, the heater is heated at a predetermined timing other than when the toner image is formed on the recording material (or image carrier), and when the toner image is formed on the recording material (or image carrier), the heater An example of stopping heat generation has been described, but the present invention is not limited to this. When forming a toner image on a recording material (or an image carrier), the amount of heat generated by the heater may be weakened as compared with a predetermined timing.

In the modified example, the amount of heat generated by the heater is controlled by the amount of electric power supplied from the power source to the heater. For example, the amount of power when forming a toner image on a recording material (or image carrier) is 10 watts, and the amount of power at a predetermined timing other than when forming a toner image on a recording material (or image carrier) is 20. Let it be watts. As for the moving mechanism for moving the cleaning member, the same configuration as that of the embodiment can be used. Also in this case, the heating efficiency of the cleaning member can be improved at a predetermined timing other than when the toner image is formed on the recording material (or the image carrier), and the deterioration of the cleaning function can be suppressed. Further, similarly to the above embodiment, the power consumption of the heater when forming the toner image can be reduced.

Further, in the above embodiment, an example including a moving mechanism (contact / detachment mechanism) for moving only the cleaning member among the cleaning member and the heater has been described, but a moving mechanism (contact / detachment mechanism) for moving both the cleaning member and the heater has been described. May be provided.

The image forming apparatus may be not a printer but a copying machine, a facsimile alone, or a multifunction device having at least two functions of a copying machine, a printer, a facsimile, and a scanner.

The preferred embodiment of the present invention has been described above. The present invention is not limited to such a specific embodiment, and unless otherwise specified in the above description, various modifications and modifications can be made within the scope of the invention described in the claims. It is possible.

Moreover, the effects described in the embodiments of the present invention merely list the most preferable effects arising from the present invention, and the effects according to the present invention are not limited to those described in the embodiments of the present invention.

1Y, 1M, 1C, 1K Image forming unit 2Y, 2M, 2C, 2K Photoreceptor 3Y, 3M, 3C, 3K Drum cleaning device 6Y, 6M, 6C, 6K Charging device 8Y, 8M, 8C, 8K Developer 30 Intermediate transfer Unit 31 Intermediate transfer belt 31a Front surface 32 Drive roller 33 Secondary transfer Back surface roller 33A Axis 34 Cleaning backup roller 35Y, 35M, 35C, 35K Primary transfer roller 37 Pre-transfer roller 38 Intermediate belt cleaning device 39 Secondary transfer power supply 40 Secondary transfer device 41 Secondary transfer unit 45 Main power supply 46 Power switch 48 Support shaft 48A End 49 Pressurized frame 49A Side plate 49B Other end side 50 Pressurizing device holding unit 50A, 50B Side plate 60 Cassette 60a Roller 61 Resist roller pair 65 Transport path 70 Power control unit 72 Controller 82 Heat generation unit 84 Thermostat 86 Harness 88 Case 90 Fixing device 91 Fixing roller 92 Pressurizing roller 100 Printer 101 Optical writing unit 401 Separation roller 402 Driven roller 403 Tension roller 404 Second blade Opposing roller 405 Secondary transfer roller 405A Shaft 406 Secondary transfer belt 407, 408 Cleaning member 470 Contact / detachment cam mechanism 471A, 471B Contact / detachment cam 472A, 472B Rotating roller 473 Contact / detachment motor 473a Drive shaft 474 Pulley 475 Drive pulley 476 Drive belt 477 Sensor 480 Pressurizing device 481A, 481B Pressurizing arm 482A, 482B Cam 483A, 483B Cam follower 484, 485 Rotation fulcrum 486 Drive motor 490 Heater unit 530 Position adjustment plate 531 Jig insertion part N1 Primary transfer nip N2 Secondary transfer nip P Material

Japanese Unexamined Patent Publication No. 2005-165143

Claims (9)

A carrier that transports recording materials and
A cleaning member that cleans the carrier and
With a heater
An image carrier that supports a toner image and
A moving mechanism for moving the cleaning member and / or the heater is provided.
An image in which the cleaning member and the heater are brought closer by the moving mechanism and heat is generated by the moving mechanism at a predetermined timing other than when the toner image is formed on the recording material. In the forming device
The moving mechanism is an image forming apparatus that also serves as a contact / detachment mechanism that brings the carrier and the image carrier into contact with each other and separates them from each other. The image forming apparatus according to claim 1 , wherein when the toner image is formed on the recording material, the heat generation of the heater is stopped. The image forming apparatus according to claim 1 , wherein when forming a toner image on a recording material, the calorific value of the heater is weakened as compared with the predetermined timing. An image carrier that supports a toner image and
A cleaning member for cleaning the image carrier and
With a heater
Photoreceptor and
A moving mechanism for moving the cleaning member and / or the heater is provided.
At a predetermined timing other than when the toner image is formed on the image carrier, the moving mechanism brings the cleaning member closer to the heater and the heater as compared with the case where the toner image is formed on the image carrier. In the image forming apparatus that generates heat
An image forming apparatus, wherein the image carrier is an intermediate transfer body that comes into contact with the photoconductor to form a transfer nip. The image forming apparatus according to claim 4 , wherein when the toner image is formed on the image carrier, the heat generation of the heater is stopped. The image forming apparatus according to claim 4 , wherein when forming a toner image on the image carrier, the calorific value of the heater is weakened as compared with the predetermined timing. The image forming apparatus according to any one of claims 1 to 6 , wherein the heater includes an automatic temperature control device. The image forming apparatus according to claim 7 , wherein the automatic temperature control device is a thermostat. The image forming apparatus according to any one of claims 1 to 8 , wherein the predetermined timing is a timing in which the apparatus main body is in a stopped state or a standby state.

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