JP5303901B2 - FIXING DEVICE, IMAGE FORMING DEVICE, FIXING DEVICE CONTROL METHOD, AND FIXING DEVICE CONTROL PROGRAM - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, an image forming apparatus, a fixing device control method, and a fixing device control program, and in particular, a fixing device including a plurality of rolls that form a nip portion, an image forming apparatus, and a fixing device control method. And a fixing device control program.

  An electrophotographic image forming apparatus (MFP (Multi Function Peripheral), facsimile machine, copying machine, printer, etc.) has a fixing device (fixing device) that fixes toner on paper (media) to the paper with heat and pressure. Is provided.

  The fixing device is generally composed of a heating roll (fixing roll) and a pressure roll, and the toner is fixed to the paper by the pressure and heat between the two rolls. The heating roll is formed of a cored bar and elastic rubber, thereby forming an NIP (nip) so that sufficient fixing performance can be secured.

  FIG. 7 is a cross-sectional view of a partial configuration of the fixing device.

  The heating roll 1521 is a roll on the toner (T) surface side of the paper (P), and its temperature greatly affects the fixing property. The roll opposite to the paper toner surface is called a pressure roll 1522.

  Regarding the hardness relationship between the two rolls, the heating roll 1521 is generally made softer than the pressure roll 1522 as shown in the figure. The reason is to prevent the paper from wrapping. Since the paper is easy to wrap around the roll on the toner surface side, the pressure roll 1522 is hardened to form an NIP shape that is easily conveyed to the pressure side. Because.

  As described above, since the pressure roll has a higher hardness, when pressure is applied to both rolls, the heating roll is pushed by the hard pressure roll and deforms.

  FIG. 8 is a diagram illustrating the bending of the roll in the NIP portion.

  The deformed heating roll 1521 forms flexures 1521a and 1521b at the NIP inlet and outlet as shown. Further, a separation claw 8 is disposed on the NIP exit side of the heating roll 1521 to prevent paper wrapping (paper is transported in the “B” direction).

  Deformation of the heating roll caused by being pressed by the above-described hard pressure roll will be described below.

  The heating roll is divided into a belt part and a roll part. By attaching a cylindrical belt part to a columnar roll part and fixing both ends with flanges, a heating roll is obtained.

  In order to fix the toner, it is necessary to form an NIP having a certain width. For this reason, a Si sponge layer is provided in the roll part which has elasticity. A cored bar layer is formed below the sponge layer to ensure the strength of the roll. Generally, Fe or Al is used as the material for the core metal layer.

  Immediately after the electrophotographic apparatus (image forming apparatus) is turned on, it is called morning one. In the morning, the sponge layer in the roll part gradually warms after the heater is turned on after the power is turned on. As the temperature increases, the outer diameter expands and the hardness increases. The time from when the heater is turned on to the completion of warm-up when the surface of the heating roll reaches a predetermined temperature (about 180 ° C.) is about 30 seconds to 1 minute.

  However, the Si sponge layer in the roll part and the Si rubber layer in the belt part are gradually stabilized in outer diameter expansion and hardness hardening over about 2 hours after the heater is turned on.

  In the morning, since the Si sponge part of the roll part is not expanded, the outer diameter is still small compared to the stable state.

  Therefore, there is still a gap between the roll part and the belt part. The belt part is deformed so as to protrude to both sides of the NIP entrance / exit by the deformation of the NIP part (FIG. 8). In the stable state, the separation claw has a gap with the heating roll set to about 0.3 to 0.5 mm. The belt that protrudes in the morning comes into contact with the separation claw. Due to this contact, streaks enter the belt and appear as image streaks.

  In the LL (low temperature and low humidity) environment, the outer diameter of the roll part in the morning is smaller than that in the HH (high temperature and high humidity) environment, so the gap between the belt part and the roll part is large, and the belt sticks out. large. For this reason, strong stripes are generated.

  The present invention has been made to solve such problems, and a fixing device, an image forming apparatus, a fixing device control method, and a fixing device control program capable of improving the state of a roll used. The purpose is to provide.

In order to achieve the above object, according to one aspect of the present invention, a fixing device for fixing a toner image formed on a medium includes at least two rolls forming a nip portion, and the at least two rolls are heating rolls. And a pressure roll having a hardness higher than that of the heating roll, and the fixing device further includes a separation claw provided on the nip exit side of the heating roll, and a deformation of the roll into the heating roll at a predetermined timing. and a heating device for providing heat as a temperature above the heating roll includes a belt portion in contact with the media, the belt unit includes a elastic member deformed by heating, the heating device, the elastic at a predetermined time against member, applying heat to the variations thereof temperature above the deformation temperature is at least one temperature higher than the highest temperature of the temperature adjustment temperature during the image formation of the roll That.

  Preferably, the predetermined timing is determined by the number of fixing times.

  Preferably, the predetermined timing is when the power is turned on.

  Preferably, the predetermined timing is a timing at regular time intervals.

According to another aspect of the invention, a fixing device for fixing a toner image formed on the media, to form a nip portion, comprising at least two rolls, at least two rolls, a pressurized hot roll, a heating roll The fixing roll further has a separation claw provided on the nip outlet side of the heating roll, and the heating roll has a temperature equal to or higher than the deformation temperature of the heating roll at a predetermined timing. A predetermined timing is after passing a cardboard having a predetermined basis weight or more.
According to still another aspect of the present invention, a fixing device that fixes a toner image formed on a medium includes at least two rolls that form a nip portion, and the at least two rolls include a heating roll and a heating roll. and a high pressure roll hardness than the fixing device further includes a separation claw which is provided to the nip exit side of the heating roll, at a predetermined timing, the heating Russia Lumpur, deformation temperature than the roll And a predetermined timing is determined based on the detection result of temperature and humidity.

According to still another aspect of the present invention, a fixing device that fixes a toner image formed on a medium includes at least two rolls that form a nip portion, and the at least two rolls include a heating roll and a heating roll. and a high pressure roll hardness than the fixing device further includes a separation claw which is provided to the nip exit side of the heating roll, at a predetermined timing, the heating Russia Lumpur, deformation temperature than the roll The predetermined timing is when the temperature is determined to be lower than the predetermined temperature and the humidity is lower than the predetermined humidity.

  According to another aspect of the present invention, an image forming apparatus includes any of the fixing devices described above.

According to still another aspect of the present invention, in a control method of a fixing device for fixing a toner image formed on a medium, the fixing device includes at least two rolls that form a nip portion, and the at least two rolls are The heating roll and a pressure roll having a higher hardness than the heating roll, the fixing device further includes a separation claw provided on the nip exit side of the heating roll, and the control method has a predetermined timing, a heating roll, a heating step of applying heat to be its role of deformation temperature or higher, the heating roll includes a belt portion in contact with the media, belts portion includes a resilient member which is deformed by heating, the heating device, against the elastic member at a predetermined timing, applying heat to the its deformation temperature or higher, deformation temperature, at least one temperature control temperature during the image formation of the roll A higher temperature than the highest temperature.
According to still another aspect of the present invention, in a control method of a fixing device for fixing a toner image formed on a medium , the fixing device includes at least two rolls that form a nip portion , and the at least two rolls are a heating roll, and a hardness higher pressure roll than the heating roll, a fixing device further includes a separation claw provided on the nip exit side of the heating roll, the control method, when a predetermined timing , the heating roll, a heating step of providing a deformation temperature or the Do that heat of the roll, the predetermined timing is later passed through a predetermined basis weight or more thick.
According to still another aspect of the present invention, in a control method of a fixing device for fixing a toner image formed on a medium , the fixing device includes at least two rolls that form a nip portion , and the at least two rolls are a heating roll, and a hardness higher pressure roll than the heating roll, a fixing device further includes a separation claw provided on the nip exit side of the heating roll, the control method, when a predetermined timing , the heating roll, a heating step of providing a Do that heat and deformation temperature above its role, the predetermined timing is determined based on the detection result of the temperature and humidity.
According to still another aspect of the present invention, in a control method of a fixing device for fixing a toner image formed on a medium , the fixing device includes at least two rolls that form a nip portion , and the at least two rolls are a heating roll, and a hardness higher pressure roll than the heating roll, a fixing device further includes a separation claw provided on the nip exit side of the heating roll, the control method, when a predetermined timing , the heating roll, a heating step of providing a Do that heat and deformation temperature than that role, predetermined timing, when the temperature is lower than a predetermined temperature, or one humidity is determined to be lower than the predetermined humidity is there.

According to still another aspect of the present invention, in a control program for a fixing device that fixes a toner image formed on a medium, the fixing device includes at least two rolls that form a nip portion, and the at least two rolls are The heating roll and a pressure roll having a higher hardness than the heating roll, the fixing device further includes a separation claw provided on the nip exit side of the heating roll, and the control program has a predetermined timing, the heating roll, to execute the heating step of providing a heat equal to or higher than deformation temperature of the roll into the computer, the heating roll includes a belt portion in contact with the media, the belt portion includes a resilient member which is deformed by heating, heating equipment, to the elastic member at a predetermined timing, applying heat to the its deformation temperature or higher, deformation temperature, at least one It is not higher temperature than the highest temperature of the temperature adjustment temperature during the image formation of the roll.
According to a further aspect of the present invention, in the control program of the fixing device for fixing a toner image formed on the medium, the fixing device forms a nip, with at least 2 filtrates Lumpur, at least two The roll has a heating roll and a pressure roll having a hardness higher than that of the heating roll , the fixing device further includes a separation claw provided on the nip exit side of the heating roll , and the control program has a predetermined timing. In this case, the heating step of applying heat to the heating roll that is equal to or higher than the deformation temperature of the roll is executed by the computer, and the predetermined timing is after passing the cardboard having a predetermined basis weight or more.
According to a further aspect of the present invention, in the control program of the fixing device for fixing a toner image formed on the medium, the fixing device forms a nip, with at least 2 filtrates Lumpur, at least two The roll has a heating roll and a pressure roll having a hardness higher than that of the heating roll , the fixing device further includes a separation claw provided on the nip exit side of the heating roll , and the control program has a predetermined timing. In this case , the computer is caused to execute a heating step for applying heat to the heating roll that is equal to or higher than the deformation temperature of the roll .
According to a further aspect of the present invention, in the control program of the fixing device for fixing a toner image formed on the medium, the fixing device forms a nip, with at least 2 filtrates Lumpur, at least two The roll has a heating roll and a pressure roll having a hardness higher than that of the heating roll , the fixing device further includes a separation claw provided on the nip exit side of the heating roll , and the control program has a predetermined timing. Then, the heating step of applying heat to the heating roll that is equal to or higher than the deformation temperature of the roll is executed by the computer, and the predetermined timing is determined that the temperature is lower than the predetermined temperature and the humidity is lower than the predetermined humidity. Is the time.

  According to these inventions, it is possible to provide a fixing device, an image forming apparatus, a fixing device control method, and a fixing device control program capable of improving the state of a roll used.

  Hereinafter, an electrophotographic image forming apparatus according to an embodiment of the present invention will be described.

  The image forming apparatus forms an image on a recording material by an electrophotographic method. The image forming apparatus includes a heat fixing device.

  The fixing device periodically rotates the heating roll at a temperature higher than the temperature control temperature at the time of fixing, thereby improving the occurrence of image streak, which has been a problem of the prior art. The heating roll in the fixing device is formed by covering a rubber part, which is an elastic body, with a tube belt.

  The rubber part is expanded by heat, but the tube belt is not thermally expanded. At room temperature, a minute gap is formed between the tube belt and the rubber. By heating to the fixing temperature (about 180 ° C.), the rubber expands and there is no gap with the tube belt. As a result, the tube belt is stretched in the circumferential direction with a certain pressure (tension).

  Increasing the temperature of the heating roll (for example, 180 ° C. → 230 ° C.) increases the thermal expansion of the rubber, resulting in higher tension. Here, the deformation of the belt portion will be described.

  The belt portion includes a fluororesin release layer, an elastic rubber layer, and a Ni layer that is an electromagnetic induction heating layer. The Young's modulus is small in the rubber layer and large in the resin layer and the Ni layer. For this reason, it is the rubber layer that is deformed by the separation claw, and the resin layer and the Ni layer are not deformed.

  On the other hand, the Young's modulus of rubber decreases with increasing temperature. For this reason, when heat and pressure are applied in a deformed state of the rubber layer, the resin layer returns from the deformed (depressed) state to the original tensioned state.

  If the temperature until returning to the original temperature is adjusted at a high temperature and lowered to the normal temperature after returning to the original state, the Young's modulus increases due to the temperature decrease, so this time it does not easily deform.

  The fixing device in the present embodiment uses this phenomenon to eliminate the paper edge on the tube and the dent due to the separation claw. That is, by periodically adjusting the temperature of the heating roll to a high temperature, the tension with which the rubber presses the tube is increased. The tube dent can be eliminated by stretching the tube with heat and pressure.

  After cooling at a high temperature for a certain period of time, the tension drops, but the tube that has been flattened without any dents remains flat.

  Thus, image streaks (heating roll streaks) and the like due to tube dents are improved by adjusting the temperature at a high temperature for about 5 minutes once every few hours.

  In order to perform such an operation, the belt of the heating roll includes an elastic member that is deformed by heating. Heat that is equal to or higher than the deformation temperature of the elastic member is applied at a predetermined timing.

  FIG. 1 is a diagram showing a configuration of an image forming apparatus according to one embodiment of the present invention.

  First, a schematic configuration of the image forming apparatus 1501 will be described. The image forming apparatus 1501 includes an intermediate transfer belt 1502 as a belt member at a substantially central portion inside the image forming apparatus 1501. The intermediate transfer belt 1502 is supported on the outer periphery of the rollers 1504 and 1505 and is driven to rotate in the direction of arrow A. The intermediate transfer belt drive roller 1505 is connected to a drive motor (not shown), and the roller 1504 is driven to rotate as the intermediate transfer belt drive roller 1505 rotates.

  Below the lower horizontal portion of the intermediate transfer belt 1502, four image forming units 1506Y, 1506M, 1506C, respectively corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), and black (K), 1506K are arranged side by side along the intermediate transfer belt 1502.

  Each of the image forming units 1506Y, 1506M, 1506C, and 1506K has a photosensitive drum 1507Y, 1507M, 1507C, and 1507K, respectively. Around each of the photosensitive drums 1507Y, 1507M, 1507C, and 1507K, the photosensitive members 1508, the print head unit 1509, the developing device 1510, and the intermediate transfer belt 1502 are sandwiched in order along the rotation direction. Primary transfer rollers 1511Y, 1511M, 1511C, and 1511K facing the drums 1507Y, 1507M, 1507C, and 1507K, and a cleaner 1512 are arranged, respectively.

  A secondary transfer roller 1503 is pressed against a portion of the intermediate transfer belt 1502 supported by the intermediate transfer belt driving roller 1505, and a nip (NIP) portion between the secondary transfer roller 1503 and the intermediate transfer belt 1502 is 2 A next transfer area 1530 is formed.

  A fixing device 1520 including a heating roll 1521, a pressure roll 1522, and a magnetic flux generation unit 1523 is disposed at a downstream position of the conveyance path 1541 behind the secondary transfer region 1530. A pressure contact portion between the heating roll 1521 and the pressure roll 1522 is a fixing NIP region 1531.

  A paper feed cassette 1517 is detachably disposed below the image forming apparatus 1501. The sheets P stacked and accommodated in the sheet feeding cassette 1517 are sent out one by one from the uppermost one to the conveyance path 1540 by the rotation of the sheet feeding roller 1518.

  An AIDC (image density) sensor 1519 also serving as a registration sensor is installed between the image forming unit 1506K on the most downstream side of the intermediate transfer belt 1502 and the secondary transfer region 1530. This registration sensor 1519 measures the interval between the patterns of the respective colors formed on the intermediate transfer belt 1502 and compares the interval with a predetermined reference value to adjust the start timing of writing the image of each color. belongs to.

  Next, a schematic operation of the image forming apparatus 1501 having the above configuration will be described.

  When an image signal is input from an external device (for example, a personal computer) to an image signal processing unit (not shown) of the image forming apparatus 1501, the image signal processing unit performs color conversion of the image signal into yellow, cyan, magenta, and black. The digital image signal is generated, and the print head unit 1509 of each of the image forming units 1506Y, 1506M, 1506C, and 1506K is caused to emit light based on the input digital signal. Thereby, electrostatic latent images for the respective colors are formed on the surfaces of the photosensitive drums 1507Y, 1507M, 1507C, and 1507K, respectively.

  The electrostatic latent images formed on the photosensitive drums 1507Y, 1507M, 1507C, and 1507K are respectively developed by the developing units 1510 to become toner images of the respective colors. Then, the toner images of the respective colors are primary-transferred by being sequentially superimposed on the intermediate transfer belt 1502 moving in the arrow A direction by the action of the primary transfer rollers 1511Y, 1511M, 1511C, and 1511K.

  The superimposed toner image formed on the intermediate transfer belt 1502 in this way reaches the secondary transfer region 1530 as the intermediate transfer belt 1502 moves. In the secondary transfer region 1530, the superimposed color toner images are secondarily transferred onto the paper P collectively by the action of the secondary transfer roller 1503.

  Next, the toner image secondarily transferred to the paper P reaches the fixing NIP area 1531. In the fixing NIP region 1531, the toner image is fixed on the paper P by the action of the heating roll 1521 and the pressure roll 1522 that generate induction heat by the magnetic flux generator 1523.

  The paper P on which the toner image is fixed is discharged to a paper discharge tray 1513 via a paper discharge roller 1514.

  The arrangement and method of each element in FIG. 1 may be changed as appropriate according to the apparatus.

  The image forming apparatus may be a monochrome / color copying machine, a printer, a FAX, or a complex machine of these.

  FIG. 2 is a diagram illustrating a cross-sectional configuration of the fixing device in FIG. 1.

  Here, a fixing device employing an electromagnetic induction heating method for a color laser printer will be described as an example.

  Referring to the figure, the fixing device includes a heating roll 1521, a pressure roll 1522, a magnetic flux generator 1523, a high frequency inverter (excitation circuit) 4, a control circuit 5, a temperature sensor 6, and a demagnetizing coil circuit 7. A separation claw 8, an excitation coil 31, a degaussing coil 34, a core 32, and a coil bobbin 33. In the figure, toner is attached to the upper surface of the paper P, and the paper P is conveyed from the left to the right in the drawing.

  Also connected to the control circuit 5 are an environmental sensor 10 for measuring the temperature and humidity of the environment, and a switch 11 that receives input from the user for eliminating streaks.

  The heating roll 1521 has a moving belt. The pressure roll 1522 has higher hardness than the heating roll.

  The heating roll 1521 and the pressure roll 1522 are arranged in parallel in the vertical direction, and both ends are rotatably supported by bearing members (not shown). The pressure roll 1522 is urged in the direction of the rotation axis of the heating roll 1521 by a pressure mechanism (not shown) using a spring or the like. A pressure roll 1522 is brought into pressure contact with a lower surface portion of the heating roll 1521 with a predetermined pressure to form a pressure nip portion (fixing nip portion).

  The pressure roll 1522 is rotationally driven in a clockwise direction indicated by an arrow at a predetermined peripheral speed by a drive mechanism (not shown). The heating roll 1521 rotates following the rotation of the pressure roll 2 by the pressure frictional force with the pressure roll 1522 at the pressure nip portion.

  Note that the heating roll 1521 may be driven to rotate, and the pressure roll 1522 may be driven to rotate. Further, the relationship between driving and driven may be reversed.

  FIG. 3 is a diagram showing a schematic concept of the heating roll 1521.

  The heating roll is divided into a belt part and a roll part. For convenience of the manufacturing process, the heating roll is manufactured by attaching a cylindrical belt portion to a columnar roll portion and fixing both ends with flanges.

  The heating roll 1521 has a layer structure, and in order from the inside to the outside, the core metal 11 as a support layer, the heat insulating layer (Si sponge layer) 12, the electromagnetic induction heating layer 13, the elastic layer (Si rubber layer) 14, and It has a five-layer structure of a release layer (fluororesin layer) 15. As the roll hardness, for example, an Asker C hardness of 30 to 90 degrees is used.

  In order to fix the toner, it is necessary to form an NIP having a certain width. For this reason, an elastic sponge layer is required. In the heating roll of FIG. 3, the sponge layer 12 is composed of Si sponge.

  A cored bar layer 11 is formed below the sponge layer 12 in order to ensure the strength of the roll. As a material of the core metal layer 11, Fe or Al is generally used.

  The belt portion is composed of an electromagnetic induction heat generating layer 13 whose lowermost layer is Ni. This functions as a heat generating layer of the IH heat fixing method. The intermediate layer includes an elastic Si rubber layer 14, which is the same as the elastic layer of the roll portion and is a layer for forming a certain NIP width. The uppermost layer is composed of a fluororesin layer 15 as a release layer. This is a layer for ensuring releasability from paper and toner.

  The metal core 11 as the support layer is made of aluminum having a thickness of 4 mm. The material only needs to be strong, and for example, iron or a heat-resistant molded pipe such as PPS (polyphenylene sulfide) can be used. However, in order to prevent the cored bar from generating heat, it is desirable to use a nonmagnetic material that is less affected by electromagnetic induction heating.

  The heat insulation layer 12 is for heat insulation holding of the electromagnetic induction heat generating layer 13, and a heat-resistant and elastic rubber material or a sponge material (heat insulation structure) of resin material is used. By using a heat-resistant and elastic rubber or resin sponge (heat insulation structure) for the heat insulating layer 12, the electromagnetic induction heat generating layer 13 is insulated and held. Further, it plays the role of allowing the deflection of the electromagnetic induction heat generating layer 13 to increase the pressure nip width and reducing the roll hardness to improve the paper discharge performance and the recording material separation performance.

  The heat insulating layer 12 may have a two-layer structure of a rubber material and a sponge body.

  For example, when a silicon sponge material is used for the heat insulating layer 12, the thickness is 2 to 10 mm (preferably 3 to 7 mm), and the hardness is 20 to 60 degrees (preferably 30 to 50 degrees) with an Asker rubber hardness meter. Is set.

  The electromagnetic induction heat generating layer 13 in the present embodiment is an endless nickel electroformed belt layer having a thickness of 10 to 100 μm (preferably 20 to 50 μm). As another material of the electromagnetic induction heat generating layer 13, a material having a relatively high magnetic permeability μ and an appropriate resistivity ρ such as a magnetic material (magnetic metal) such as magnetic stainless steel may be used. Furthermore, even a nonmagnetic material can be used by making the material a thin film as long as it is a conductive material such as metal.

  The electromagnetic induction exothermic layer 13 may be a resin in which exothermic particles are dispersed. Separation can be improved by using a resin-based material for the electromagnetic induction heat generating layer 13.

  Next, the elastic layer 14 will be described. The elastic layer 14 serves to increase the adhesion between the recording material and the surface of the heating roll. The elastic layer 14 is a layer of a rubber material or a resin material that is a foam member having heat resistance and elasticity, and a heat resistant elastomer such as silicon rubber or fluoro rubber that can withstand use at a fixing temperature can be used.

  Various fillers may be mixed into the elastic layer 14 for the purpose of improving thermal conductivity, reinforcing, or the like. Examples of the thermally conductive particles include diamond, silver, copper, aluminum, marble, and glass. Practically, silica, alumina, magnesium oxide, boron nitride, beryllium oxide, and the like are used.

  For example, the thickness of the elastic layer 14 is preferably 10 to 800 μm, and more preferably 100 to 300 μm. When the thickness of the elastic layer is less than 10 μm, it is difficult to obtain the desired elasticity in the thickness direction. On the other hand, when the thickness exceeds 800 μm, the heat generated in the heat generating layer hardly reaches the outer peripheral surface of the fixing film, and the thermal efficiency tends to deteriorate.

  The elastic layer 14 is preferably made of silicon rubber having a JIS hardness of 1 to 80 degrees (desirably 5 to 30 degrees). Within this JIS hardness range, it is possible to prevent poor toner fixability while preventing a decrease in strength of the elastic layer and poor adhesion.

  Specifically, one-component, two-component or three-component or more silicone rubber, LTV type, RTV type or HTV type silicon rubber, condensation type or addition type silicon rubber can be used as this silicon rubber. . In the present embodiment, the elastic layer 14 is a silicon rubber layer having a JIS hardness of 10 degrees and a thickness of 200 μm.

  The outermost release layer 15 is for enhancing the release property of the heating roll surface. The release layer 15 can withstand use at the fixing temperature and has toner release properties. As the release layer 15, for example, silicon rubber, fluororubber, or fluororesin such as PFA, PTFE, FEP, and PFEP is preferably used. 5-100 micrometers is preferable and, as for the thickness of a mold release layer, 10-50 micrometers is more preferable. Further, in order to improve the interlayer adhesion, an adhesion treatment with a primer or the like may be performed. In addition, a conductive material, an abrasion resistant material, and a good heat conductive material can be added to the release layer 15 as necessary.

  The heating roll can be composed of at least four layers of a support layer (core metal), a heat insulating layer, an electromagnetic induction heat generating layer, and a release layer in order from the inside to the outside, and further corresponds to a color image. Therefore, it is desirable to provide the elastic layer 14.

  The magnetic flux generator 1523 is disposed outside the heating roll 1521 and causes the generated magnetic flux to act on the electromagnetic induction heat generating layer 13 from the outer surface side of the heating roll 1521.

  Since the heat capacity of the electromagnetic induction heat generating layer 13 that contributes to heat generation and generates eddy current is small, and the electromagnetic induction heat generating layer 13 is insulated and held by the sponge layer 12, the elastic layer 14 on the heating roll surface layer side or the separation layer is separated. The mold layer 15 is rapidly heated. The surface of the heating roll can quickly reach the temperature necessary for fixing, and can catch up with the supply of heat even if the paper P such as paper or OHP sheet is deprived of heat.

  FIG. 4 is a diagram showing a schematic configuration of the pressure roll 1522.

  The pressure roll 1522 has an elastic layer 22 made of silicon sponge rubber having a thickness of 3 to 10 mm on the outer periphery of an aluminum core bar 21 having a thickness of 3 mm, and further improves the surface releasability like the heating roll 1521. The mold release layer 25 is provided.

  As the release layer 25, for example, a fluororesin release layer having a thickness of 10 to 50 μm such as PTFE or PFA is provided to form a roller.

  As long as the material of the core metal 21 can secure the strength, for example, a pipe of a heat resistant mold such as iron or PPS (polyphenylene sulfide) can be used. It is desirable to use a nonmagnetic material that is less affected by induction heating.

  The pressure roll 1522 is pressed against the heating roll 1521 with a load of 300 to 500N. In this case, the nip width is about 5 to 15 mm. Depending on circumstances, the nip width may be changed by changing the load.

  The thickness of the heat insulating layer 22 can be appropriately changed in accordance with the use conditions in the range of 3 to 10 mm. The heat insulating layer 22 may have a two-layer structure of silicon rubber and silicon sponge.

  Note that the material and configuration of the roll and the like are not limited to the present embodiment. The time may be changed according to the device.

  The recording material P introduced into the pressure nip between the heating roll 1521 and the pressure roll 1522 is nipped and conveyed by the pressure nip and heated by the heating roll 1521. As a result, the unfixed toner image is melted and fixed on the paper P.

  The paper P that has passed through the pressure nip is separated from the heating roll 1521 and discharged and conveyed. The separation claw 8 is disposed in contact with the surface of the heating roll 1521. The separation claw 8 forcibly separates the paper P from the surface of the heating roll 1521 and prevents jamming when the paper P sticks to the surface of the heating roll 1521 after passing the pressure nip portion.

  FIG. 5 is a diagram showing the time until the streak (scratch) due to the separation claw 8 attached to the heating roll 1521 disappears.

  The inventor of the present application experimentally attached a streak similar to an actual streak to the heating roll, and then heated the heating roll to a different temperature and idled it. It was experimented how many minutes later the streak disappears by idling at various temperatures.

  As shown in FIG. 5, when the heating roll temperature is adjusted to a high temperature of 220 ° C. to 230 ° C., the streaks attached to the belt disappear in a short time of 5 minutes to 10 minutes. On the other hand, at 190 to 210 ° C., it takes 50 minutes or more. The reason why there is a large difference in time between temperatures up to 210 ° C. and 220 ° C. and 230 ° C. is presumed to be because the manner of deformation of the molecular arrangement changes greatly at that point.

  FIG. 6 is a flowchart illustrating a control method of the fixing device.

  In step S101, it is determined whether a predetermined timing for eliminating the streaks of the heating roll has come. If YES, in step S103, the heating roll is controlled to a predetermined temperature or higher. That is, since the belt of the heating roll includes an elastic member that is deformed by heating, heat that is equal to or higher than the deformation temperature of the elastic member is given to the elastic member at a predetermined timing.

  The deformation temperature due to heating of the belt is higher than the highest temperature control temperature during image formation of the heating roll. That is, for example, when the temperature of the heating roll at the time of fixing is 180 ° C., the heating roll is heated to a temperature of about 220 ° C. to 230 ° C. in step S103 of FIG.

  The predetermined timing is one of the following timings.

  (1) Timing determined based on the number of fixing times. That is, after a predetermined number of times of fixing, the heating roller is heated to a predetermined temperature in order to eliminate streaks attached to the belt.

  (2) After passing cardboard having a basis weight of 200 g or more (predetermined weight or more). When the thick paper is passed through the fixing device, the deformation (deflection) of the roll becomes larger than when the plain paper is passed. This increases the possibility that the roll surface will hit the separation claw, thereby eliminating streaks.

  (3) At startup by turning on the power. Before the image forming apparatus is used, streaks of the heating roller are eliminated.

  (4) Timing at regular time intervals. Every time the predetermined time elapses, streaks of the heating roller are eliminated.

  (5) Timing determined based on temperature and humidity detection results by a temperature and humidity detector (environmental sensor). For example, in the HH environment, it is difficult for the heating roller to be streaked. Therefore, it is not necessary to eliminate the heating roller streak, and the heating roller streak is eliminated only in the LL environment.

  (6) When the temperature and humidity detector determines that the temperature is lower than the predetermined temperature and the humidity is lower than the predetermined. This is the same as (5) above.

  (7) Timing when the user (operator) presses the switch 11 (FIG. 2). In other words, the user presses the switch 11 when streaks appear in the image printed on the medium. As a result, the heating roller is heated to a predetermined temperature, and streaks attached to the belt are eliminated.

  [Effects of the embodiment]

  As described above, according to the present embodiment, the belt includes the elastic member that is deformed by heating, and heat that is equal to or higher than the deformation temperature is applied to the elastic member at a predetermined timing. Thereby, streaks of the heating roll due to the separation claw or the like are improved.

  That is, the heating roll is caused to thermally expand by periodically adjusting the temperature of the heating roll at a high temperature. This increases the pressure on the belt and improves streaks due to separation claw marks and the like.

  [Others]

  The image forming apparatus may be any one of a monochrome / color copying machine, a printer, a facsimile machine, and a complex machine (MFP) thereof.

  Further, the processing in the above-described embodiment may be performed by software or by using a hardware circuit.

  In addition, a program for executing the processing in the above-described embodiment can be provided, and the program is recorded on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, and a memory card and provided to the user. You may decide to do it. The program may be downloaded to the apparatus via a communication line such as the Internet.

  In addition, it should be thought that the said embodiment is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1 is a diagram illustrating a configuration of an image forming apparatus according to one embodiment of the present invention. FIG. 2 is a diagram illustrating a cross-sectional configuration of the fixing device in FIG. 1. It is a figure which shows the schematic concept of the heating roll 1521. FIG. 5 is a diagram showing a schematic configuration of a pressure roll 1522. It is a figure which shows time until the stripe (scratch) by the separation nail | claw 8 attached to the heating roll 1521 disappears. 5 is a flowchart illustrating a fixing device control method. FIG. 3 is a cross-sectional view of a partial configuration of the fixing device. It is a figure which shows the bending of the roll in a NIP part.

Explanation of symbols

8 Separation Claw 10 Environmental Sensor 11 Switch 1501 Image Forming Device 1502 Intermediate Transfer Belt 1503 Secondary Transfer Roller 1504 Intermediate Transfer Belt Tension Roller 1505 Intermediate Transfer Belt Drive Roller 1506Y, M, C, K Image Forming Unit 1507Y, M, C, K 107 Photosensitive drum 1508 Charger 1509 Print head unit 1510 Developer 1511Y, M, C, K Primary transfer roller 1512 Cleaner 1513 Paper discharge tray 1514 Paper discharge roller 1517 Paper feed cassette 1518 Paper feed roller 1519 AIDC (image density) sensor 1520 Fixing device 1521 Heating roll 1522 Pressure roll 1523 Magnetic flux generation unit 1530 Secondary transfer area 1531 Fixing NIP area 1540, 1541, 1542 Transport path P Paper

Claims (16)

A fixing device for fixing a toner image formed on a medium,
Comprising at least two rolls forming a nip,
The at least two rolls include a heating roll and a pressure roll having a higher hardness than the heating roll, and the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll;
When it comes to a predetermined timing, the heating roll is provided with a heating device that applies heat that is equal to or higher than the deformation temperature of the roll ,
The heating roll includes a belt portion in contact with the medium,
The belt portion includes an elastic member that is deformed by heating,
The heating device provided for the elastic member at a predetermined timing, the heat becomes its deformation temperature than on,
The fixing device , wherein the deformation temperature is higher than a temperature at which a temperature adjustment temperature is highest during image formation of the at least one roll . The fixing device according to claim 1, wherein the predetermined timing is determined by the number of times of fixing. The fixing device according to claim 1, wherein the predetermined timing is when the power is turned on. The fixing device according to claim 1, wherein the predetermined timing is a timing at regular time intervals. A fixing device for fixing a toner image formed on a medium,
Comprising at least two rolls forming a nip,
The at least two rolls include a heating roll and a pressure roll having a higher hardness than the heating roll, and the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll;
When it comes to a predetermined timing, the heating roll is provided with a heating device that applies heat that is equal to or higher than the deformation temperature of the roll ,
Wherein the predetermined timing is passed through a predetermined basis weight or more thick, constant Chakusochi. A fixing device for fixing a toner image formed on a medium,
Comprising at least two rolls forming a nip,
The at least two rolls include a heating roll and a pressure roll having a higher hardness than the heating roll, and the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll;
When it comes to a predetermined timing, the heating roll is provided with a heating device that applies heat that is equal to or higher than the deformation temperature of the roll ,
Wherein the predetermined timing is determined based on the detection result of the temperature and humidity, constant Chakusochi. A fixing device for fixing a toner image formed on a medium,
Comprising at least two rolls forming a nip,
The at least two rolls include a heating roll and a pressure roll having a higher hardness than the heating roll, and the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll;
When it comes to a predetermined timing, the heating roll is provided with a heating device that applies heat that is equal to or higher than the deformation temperature of the roll ,
Wherein the predetermined timing is when the temperature is lower than the predetermined temperature, and humidity is determined to be lower than the predetermined humidity, constant Chakusochi. It provided with a fixing device according to any one of claims 1 to 7, the image forming apparatus. A method for controlling a fixing device for fixing a toner image formed on a medium, comprising:
The fixing device includes at least two rolls forming a nip portion,
The at least two rolls include a heating roll and a pressure roll having a higher hardness than the heating roll, and the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll is provided, and the control method includes:
When the predetermined timing is reached, the heating roll is provided with a heating step for applying heat that is equal to or higher than the deformation temperature of the roll ,
The heating roll includes a belt portion in contact with the medium,
The belt portion includes an elastic member that is deformed by heating,
The heating device provided for the elastic member at a predetermined timing, the heat becomes its deformation temperature than on,
The fixing device control method , wherein the deformation temperature is higher than a temperature at which a temperature adjustment temperature is highest during image formation of the at least one roll . A method for controlling a fixing device for fixing a toner image formed on a medium, comprising:
The fixing device includes at least two rolls forming a nip portion,
The at least two rolls are a heating roll and a pressurization whose hardness is higher than that of the heating roll. And the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll is provided, and the control method includes:
When the predetermined timing is reached, the heating roll is heated to a temperature equal to or higher than the deformation temperature of the roll. A heating step to give,
The predetermined timing is a method of controlling the fixing device after passing a cardboard having a predetermined basis weight or more. Law. A method for controlling a fixing device for fixing a toner image formed on a medium, comprising:
The fixing device includes at least two rolls forming a nip portion,
The at least two rolls are a heating roll and a pressurization whose hardness is higher than that of the heating roll. And the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll is provided, and the control method includes:
When the predetermined timing is reached, the heating roll is heated to a temperature equal to or higher than the deformation temperature of the roll. A heating step to give,
The predetermined timing is determined based on the detection result of temperature and humidity, and is controlled by the fixing device. Your method. A method for controlling a fixing device for fixing a toner image formed on a medium, comprising:
The fixing device includes at least two rolls forming a nip portion,
The at least two rolls are a heating roll and a pressurization whose hardness is higher than that of the heating roll. And the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll is provided, and the control method includes:
When the predetermined timing is reached, the heating roll is heated to a temperature equal to or higher than the deformation temperature of the roll. A heating step to give,
The predetermined timing is such that the temperature is lower than the predetermined temperature and the humidity is lower than the predetermined humidity. A control method of the fixing device when it is determined that A control program for a fixing device for fixing a toner image formed on a medium,
The fixing device includes at least two rolls forming a nip portion,
The at least two rolls include a heating roll and a pressure roll having a higher hardness than the heating roll, and the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll is provided, and the control program is
When the predetermined timing is reached, the computer is caused to perform a heating step for applying heat to the heating roll that is equal to or higher than the deformation temperature of the roll ,
The heating roll includes a belt portion in contact with the medium,
The belt portion includes an elastic member that is deformed by heating,
The heating device provided for the elastic member at a predetermined timing, the heat becomes its deformation temperature than on,
The fixing program is a control program for a fixing device, wherein the deformation temperature is higher than a temperature at which a temperature adjustment temperature at the time of image formation of the at least one roll is highest . A control program for a fixing device for fixing a toner image formed on a medium,
The fixing device includes at least two rolls forming a nip portion,
The at least two rolls are a heating roll and a pressurization whose hardness is higher than that of the heating roll. And the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll is provided, and the control program is
When the predetermined timing is reached, the heating roll is heated to a temperature equal to or higher than the deformation temperature of the roll. Let the computer perform the heating step to give,
The predetermined timing is after the control sheet of the fixing device is passed through a thick paper having a predetermined basis weight or more. Program. A control program for a fixing device for fixing a toner image formed on a medium,
The fixing device includes at least two rolls forming a nip portion,
The at least two rolls are a heating roll and a pressurization whose hardness is higher than that of the heating roll. And the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll is provided, and the control program is
When the predetermined timing is reached, the heating roll is heated to a temperature equal to or higher than the deformation temperature of the roll. Let the computer perform the heating step to give,
The predetermined timing is determined based on the detection result of temperature and humidity, and is controlled by the fixing device. Your program. A control program for a fixing device for fixing a toner image formed on a medium,
The fixing device includes at least two rolls forming a nip portion,
The at least two rolls are a heating roll and a pressurization whose hardness is higher than that of the heating roll. And the fixing device further includes:
A separation claw provided on the nip exit side of the heating roll is provided, and the control program is
When the predetermined timing is reached, the heating roll is heated to a temperature equal to or higher than the deformation temperature of the roll. Let the computer perform the heating step to give,
The predetermined timing is such that the temperature is lower than the predetermined temperature and the humidity is lower than the predetermined humidity. The fixing device control program when it is determined.

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