JP6686300B2 - Fixing device and image forming apparatus - Google Patents

Description

  The present invention relates to a thermal fixing device in an electrophotographic image forming device, and an image forming device such as a copying machine, a printer, or a facsimile equipped with the fixing device.

  In image forming apparatuses such as copiers, printers, and facsimiles, a toner image is formed on an image carrier based on image information, the toner image is transferred onto a recording material such as paper or an OHP sheet, and the toner image is carried. The recording material is passed through a fixing device to fix the toner image on the recording material by heat and pressure.

  A belt and film type fixing device is used as an energy saving fixing device, and a technique of selectively heating an area corresponding to a paper width size has been proposed.

"Paper width heating with plate heater and film method"
For example, the fixing device of Patent Document 1 includes a thin-walled cylindrical heat-resistant film, a plate-shaped heating body that comes into contact with the film, and a pressure roller, and sandwiches the recording material between the film and the pressure roller so as to make them adhere to each other. Apply thermal energy to the recording material. Since the film is as thin as about 100 μm, it is only necessary to raise the temperature of the plate-shaped heating body having a substantially small heat capacity for start-up, so the rise time can be shortened and preheating power can be reduced.

  In Patent Document 2, at least one of the resistance value of the plurality of heating resistors formed between the electrodes and the interval between the heating resistors is adjusted. This is effective in a structure in which the base material is ceramic and has a high thermal conductivity, but in the glass heater base material for improving the heating characteristics, if the spacing between the heating resistors is wide, the temperature unevenness of the heat generation is large. Therefore, there is a problem that the image quality is deteriorated.

  Conventionally, in a fixing device of a type that has a fixing member and a pressure member, and an inner peripheral surface of the fixing member and a fixed pressing member (nip forming member, heat source, etc.) slide in contact with each other, the rotational driving torque is reduced. For this purpose, a lubricant such as grease or oil has been applied to the inner surface of the fixing member. The viscosity of the lubricant changes depending on its own temperature, and the viscosity becomes high especially in a low temperature state. If the coefficient of static friction is high at the moment of starting the rotational driving of the fixing device, the torque becomes high, and in some cases, a problem such as slipping occurs between the fixing member and the pressing member. When the slip occurs, the recording material is not fed at the linear velocity when the paper is passed, and a jam occurs, or an abnormal image in which a trace of rubbing of peripheral members remains is generated.

  Therefore, an object of the present invention is to prevent high torque and slip from occurring when the fixing device is rotationally driven, and to prevent leakage of the lubricant.

In order to solve this problem, the present invention provides an endless fixing member having flexibility, a pressure member that forms a fixing nip by contact with the fixing member, and a heat source that heats the fixing member by heat conduction. In a fixing device for fixing an unfixed image on a recording material in the fixing nip, a lubricant is applied to the inner surface of the fixing member, and the heat source is divided into a plurality of pieces in the longitudinal direction of the heat source. A plate-shaped heating element having a controllable heating area, wherein in order to suppress the leakage of the lubricant from the longitudinal end of the fixing member, the heating area of The heating region at the central portion in the longitudinal direction is heated first, and then the heating region at the end portions in the longitudinal direction is heated.

  The lubricant that has accumulated on the inner surface of the fixing member and has increased in viscosity due to natural cooling and heat dissipation of the fixing device while the rotation of the fixing device is stopped is heated, and the viscosity can be reduced. As a result, the torque peak at the start of rotational driving of the fixing device can be reduced, and slippage between the pressure member and the fixing member due to high torque at the start of rotational driving can be suppressed. In addition, the viscosity of the lubricant in the central portion is reduced by heating the heating area in the central portion, and the heat is gradually transferred from the central portion to the end portion due to heat conduction in the member, so the lubricant viscosity at the end portion is also increased. It can be lowered to some extent, and the leakage of the lubricant from the belt end portion is also suppressed.

FIG. 2 is a schematic view of a cross section of the image forming apparatus. FIG. 3 is a schematic cross-sectional view of the fixing device according to the embodiment. FIG. 3 is a partially enlarged view of FIG. 2. It is an enlarged sectional view of a heater 56. It is a schematic diagram showing the composition of heater 56. It is a schematic diagram showing another composition of heater 56. 6 is a graph showing the relationship between the surface temperature of the fixing belt in the longitudinal direction of the heater and the heat generation density of the heater during continuous sheet feeding. 5 is a schematic cross-sectional view of a fixing device according to a second exemplary embodiment. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic view of a cross section of an image forming apparatus.
As shown in FIG. 1, a printer as an example of the image forming apparatus according to the present exemplary embodiment includes a sheet feeding unit 4, a registration roller pair 6, a photosensitive drum 8 as an image carrier, a transfer unit 10, It has a fixing device 12 and the like.

  The paper feeding means 4 feeds the paper feed tray 14 in which the paper P as a recording material is accommodated in a stacked state and the paper P accommodated in the paper feed tray 14 in order of separating from the top one by one. It has rollers 16 and the like. The paper P sent out by the paper feed roller 16 is temporarily stopped by the registration roller pair 6 and the misalignment is corrected. After that, at the timing synchronized with the rotation of the photosensitive drum 8, that is, at the timing when the front end of the toner image formed on the photosensitive drum 8 and the predetermined position of the front end of the paper P in the transport direction coincide, the paper P It is sent to the transfer portion N by the pair of registration rollers 6. A toner image is formed on the sheet P at the transfer portion N.

  Around the photoconductor drum 8, a cleaning unit 24 having a cleaning blade 24a, a charging roller 18 as a charging unit, a mirror 20, and a developing unit having a developing roller 22a are arranged in the order of rotation directions indicated by arrows in the figure. 22 and the transfer means 10 and the like are arranged. The mirror 20 constitutes a part of the exposure means. Between the charging roller 18 and the developing means 22, the exposure light Lb is applied to the exposure section 26 on the photoconductor drum 8 via the mirror 20, and scanning is performed.

The image forming operation in the printer is performed in the same manner as the conventional one.
That is, when the photoconductor drum 8 starts to rotate, the surface of the photoconductor drum 8 is uniformly charged by the charging roller 18, and the exposure light Lb is irradiated and scanned on the exposure unit 26 based on the image information to be created. An electrostatic latent image corresponding to the image is formed.

  This electrostatic latent image is moved to the developing means 22 by the rotation of the photosensitive drum 8, and the toner is supplied there to be visualized to form a toner image. The toner image formed on the photosensitive drum 8 is transferred onto the paper P that has entered the transfer portion N at a predetermined timing by applying a transfer bias by the transfer unit 10.

The sheet P carrying the toner image is conveyed toward the fixing device 12, fixed by the fixing device 12 having the fixing belt 28 and the pressure roller 30, and then discharged and stacked on the discharge tray.
The residual toner remaining on the photosensitive drum 8 without being transferred onto the sheet P at the transfer portion N reaches the cleaning means 24 as the photosensitive drum 8 rotates, and while passing through the cleaning means 24, the cleaning blade. It is scraped off and cleaned by 24a.
After that, the residual potential on the photoconductor drum 8 is removed by the charge eliminating means provided in the fixing device, and the next image forming step is prepared.

2 and 3 are schematic cross-sectional views of the fixing device according to the embodiment.
<Belt configuration>
The fixing device 12 has a fixing belt 28 which is an endless fixing member having flexibility, and a pressure roller 30 as a pressure member which forms a fixing nip SN by contact with the fixing belt 28. The fixing belt 28 has a nickel base having an outer diameter of about 30 mm and a thickness of about 10 to 70 μm, and an elastic layer coated on the surface of the base. The elastic layer is formed of, for example, silicon rubber having excellent heat resistance, and has a thickness of about 50 to 150 μm.

On the outermost layer of the fixing belt 28, a fluorine-based resin such as PFA or PTFE is formed as a release layer in order to improve durability and heat resistance and ensure toner releasability, and the thickness thereof is about 5 to 50 μm. is there.
Further, the fixing belt substrate is not limited to nickel, but may be a metal substrate such as SUS or a heat resistant resin such as polyimide (PI).

  A stay 61, which is a support member, is arranged inside the fixing belt, and both ends of the stay 61 are connected to the device side plates. The stay 61 receives the pressing force of the pressure roller 30 and forms a fixing nip SN. At the location of the fixing nip SN, a heater holding member 57 having a pressing portion 60 (see FIG. 3) and a pressure roller 30 are installed and connected to the apparatus side plate to support the fixing belt 28. The heater holding member 57 is supported by the stay 61.

<Pressure roller and fixing nip>
In FIG. 2, a pressure roller 30 as a pressure member has an outer diameter of about 30 mm and includes a solid or hollow iron cored bar 30a and an elastic layer 30b formed on the surface of the cored bar 30a. There is.

  The elastic layer 30b is made of, for example, silicon rubber having excellent heat resistance and has a thickness of about 5 mm. It is desirable to form a fluororesin layer having a thickness of about 40 μm on the surface of the elastic layer 30b in order to enhance the releasability. The silicon rubber forming the elastic layer may be solid rubber, but sponge rubber may be used when there is no heater inside the pressure roller. Sponge rubber is more preferable because it has higher heat insulation and is less likely to absorb heat from the fixing belt 28.

  Referring to FIG. 3, the pressure roller 30 is pressed against the fixing belt 28 by the biasing means. The pressure roller 30 presses against the heat transfer member 50 via the fixing belt 28 to form the fixing nip SN. The heater 56 and the heat transfer member 50 are pressed against the surface of the fixing belt 28 by another biasing means.

<Around the heater>
FIG. 4 is an enlarged sectional view of the heater 56.
The heater 56, which is a heat source for heating the fixing belt 28, is a plate-shaped heating element in which a resistance heating element 56a is formed on a low thermal conductivity base material 56b made of ceramics such as glass or alumina. More specifically, the resistance heating element 56a is screen-printed and fired on the low thermal conductivity base material 56b, and the overcoat (OC) layer 56c is further formed on the low thermal conductivity base material 56b. As a result, the resistance heating element 56a is insulated from the outside. The OC layer 56c located on the fixing belt 28 side is also formed of glass or the like, but it is thinner than the low thermal conductivity base material 56b and heat is more easily transferred to the OC layer side than to the base material side. Heating efficiency is improved.

  The temperature of the fixing belt 28 is increased by heat transfer by bringing the heat transfer member 50, which is heated in contact with the heater 56, into sliding contact with the inside of the fixing belt 28 such as a film or a sleeve, and is conveyed to the fixing nip SN. The unfixed image on the sheet of paper P can be heated and fixed.

  The heat transfer member 50 is made of a high heat conductive material such as copper or aluminum, and contacts the heater 56 to transfer heat from the surface of the heater 56 to the fixing belt 28. By interposing a heat conductive grease or a heat conductive sheet between the heater 56 and the heat transfer member 50, the adhesion thereof is improved, and the heat transfer property to the front surface is improved rather than the heat transfer to the back surface of the heater to improve the belt heating characteristic. At the same time, the heat transfer in the longitudinal direction of the heater is improved to ensure uniform heating.

Further, in FIG. 3, the heater holding member 57 is in contact with the back surface of the heater 56 and holds it. The heater holding member 57 is not in contact with the entire back surface, but is in partial contact so that heat conduction to the heater holding member 57 is minimized. The heater holding member 57 is made of a material having a low thermal conductivity such as a heat resistant resin such as LCP. Although the fixing belt 28 and the heat transfer member 50 are in contact with each other to form the fixing nip SN, a region projecting to the belt side with respect to this contact surface is formed by the pressing portion 60 before and after the nip, and the paper P is thereby formed. Separation is improved.
The heat transfer member 50, the heater 56, the heater holding member 57, and the like function as a nip forming member that forms a fixing nip SN between the pressure roller 30 and the fixing belt 28.

5 and 6 are schematic views showing the configuration of the heater 56.
In FIG. 5, the plate-shaped heater 56 has a resistance heating element 56a in a longitudinal direction perpendicular to the sheet conveying direction, and the resistance heating element 56a has a plurality of heating regions (regions 1 to 5). Individual heating lines [1 to 5 ch] and common lines [com. ] Is connected to each of the heating regions, and each of the heating regions can be individually controlled by turning on / off the five switches SW that connect the heating region to the power source 40. Each heating region (regions 1 to 5) is composed of a plurality of heating elements. For example, in the region 3 of FIG. 5, a resistance heating element is formed on the comb-teeth-shaped electrode and 10 heating elements heat the area. Areas 1 and 5 are formed by seven heating elements, but the interval between the comb-teeth-shaped electrodes is narrower than areas 2 to 4, and the divided heating portions are also narrowed. The amount of heat generated per unit length is high.

  In the modified example of the heater 56 shown in FIG. 6, the regions 1 to 5 are formed by forming the individual resistance heating elements 56a on the opposing electrodes. For example, in the region 3, ten resistance heating elements 56a are formed at equal intervals, and in the regions 1 and 5, three wider resistance heating elements 56a are formed at equal intervals. As a result, the density of the amount of heat generated is increased in the end regions 1 and 5, and the amount of heat generated per unit length in the longitudinal direction can be increased.

  In addition, in FIG. 6, each heating region and the power source 40 are connected by three switches SW. In this way, the power supplies of the heating regions (regions 1, 5 and regions 2, 4) located symmetrically from the longitudinal center (region 3) are turned on / off at the same time. This can reduce the number of switch elements such as triacs and FETs for turning on / off.

  In the heater 56 shown in FIGS. 5 and 6, the heating region is divided into five, but it is also possible to divide into nine or three.

<Sensor and heating control / pressurization detection>
In FIG. 2, the fixing device 12 has a thermistor 34 as a temperature detecting means for detecting the surface temperature of the fixing belt 28 downstream of the fixing nip SN and a thermistor 36 as a heater temperature detecting means for detecting the temperature of the heater 56. . Further, the fixing device 12 has a power source 40 for supplying electric power to the heater 56, and a heating control means 42 for controlling the power source 40 based on the detection information of the thermistors 34, 36.

  The external heating control means 42 means a microcomputer including a CPU, a ROM, a RAM, an I / O interface and the like.

  The fixing device 12 also includes a thermistor 39 as a temperature detecting means for detecting the surface temperature of the pressure roller 30. The thermistor 39 may be of a type that is always in contact with the surface layer, or may be a non-contact type that is installed with a slight gap. The contact type is superior in responsiveness and accuracy, but the contact mark of the thermistor remains on the surface layer. Further, if a plurality of thermistors are installed in the longitudinal direction of the pressure roller 30, the temperature at each location such as the central portion and the end portion can be detected and grasped with higher accuracy, and more accurate heater control can be performed. It is possible to provide information to do.

  Therefore, the heating control of the heater 56 installed in the fixing nip SN is performed according to the temperature of the pressure roller 30 detected by the thermistor 39. When the pressure roller 30 is warm immediately after the sheet is passed, the temperature around the fixing nip is also high, so that the viscosity of the lubricant is low. However, as the temperature of the pressure roller decreases and the temperature around the fixing nip also decreases, the viscosity of the lubricant gradually increases accordingly. Therefore, the pressure roller temperature that gradually decreases is detected, and the heater 56 (the resistance heating element 56a provided on the insulated substrate) provided in the fixing nip is controlled according to the detected temperature. To do. As a result, since the viscosity of the lubricant around the fixing nip can be reduced by heating the fixing belt 28 only when the fixing device 12 is cold while the rotation of the fixing belt 28 is stopped, there is no unnecessary power consumption and an energy saving effect is obtained. You can

  Further, in accordance with the temperature of the pressure roller 30 detected by the thermistor 39, which heating area in the heater 56 divided in the longitudinal direction of the fixing nip SN is selected and controlled. For example, when the temperature of the pressure roller is extremely low, heating is performed over a wide range in a plurality of heating regions at the central portion and the end portions. On the other hand, when the pressure roller temperature is not so low, heating is performed only in the central heating area (limited to the narrow heating area). The condition of the lubricant viscosity is predicted and calculated according to the temperature of the pressure roller detected by the thermistor 39, and heating is performed in a heating region corresponding to the temperature, so that the excess region is not heated, and heating is sufficient. Therefore, an energy saving effect can be obtained.

  Further, in accordance with the temperature gradient of the pressure roller 30 detected by the thermistor 39, which heating area in the heater 56 divided in the longitudinal direction of the fixing nip SN is selected and controlled. After passing the paper, the pressure roller 30 gradually radiates heat naturally, and the temperature decreases. The temperature gradient with respect to time is when the entire pressure roller is warm (for example, after continuous paper feeding) and when only the pressure roller surface layer is warm (for example, after a few papers have passed since the first startup in the morning). And is different. Specifically, when the gradient is large (for example, after passing a small number of sheets from the start-up in the morning), heating is performed over a wide range in the heating areas at the central portion and the end portions, and when the gradient is small ( For example, after continuous paper feeding), heating is performed in the heating area only in the central portion. Since the viscosity of the lubricant also varies depending on the temperature gradient of the pressure roller 30, wasteful power consumption can be avoided and more energy saving effect can be obtained by performing heating control in a heating region that is optimal for the temperature gradient.

  As described above, the heater 56 provided in the fixing nip is properly and accurately controlled based on the temperature information detected by the thermistor 39 of the pressure roller 30.

<Control>
FIG. 7 is a graph showing the relationship between the surface temperature of the fixing belt and the heat generation density of the heater in the heater longitudinal direction during continuous sheet feeding in the heater of FIGS. 5 and 6.
Each heating area (areas 1 to 5) of the heater 56 can be heated independently, and the heating control unit 42 changes the heating rate of the heater 56 based on the paper size information of the paper P. For example, when the paper passing width of the paper P corresponds to the paper passing area a, the heating area corresponding to the paper passing area a is heated so that the temperature of the non-paper passing area b does not become too high. By controlling the heating according to the paper size information, it is possible to prevent the damage of each member and the deterioration of the image quality due to the excessive temperature rise of the non-sheet passing portion b.

  At this time, the power supply may be completely stopped in the heating area corresponding to the non-sheet passing area b, but if the fixing belt temperature is too low, the rising to the fixing temperature in the next image area may not be completed in time. is there. For this reason, the temperature is controlled so as to keep the fixing belt at a second target temperature that is lower than the first target temperature corresponding to the image area but is a predetermined value or higher than room temperature, and corresponds to the non-sheet passing area b. Power is also supplied to the parts.

  The fixing belt 28 and the pressure roller 30 are rotationally driven during the passage of the paper, and at the same time, the fixing belt 28 is heated by the heater 56 provided inside the fixing belt 28 corresponding to the fixing nip SN. Low viscosity and low sliding resistance. However, after the paper passing job is completed, the rotation is stopped, and if there is no next paper passing job in the standby state or the sleep state for a while, the temperature of the pressure roller and the temperature around the nip are gradually lowered, and the lubricant temperature is gradually lowered, so that the viscosity is decreased. To rise. Therefore, when the rotation of the fixing belt 28 is stopped, by heating the heater 56 in the region 3 at the center in the longitudinal direction shown in FIGS. 5 and 6, it is possible to suppress the increase in the viscosity of the lubricant. The temperature of the fixing belt 28 and the central portion in the longitudinal direction around the nip is eventually conducted to both ends, and the increase in the viscosity of the lubricant at the ends can be suppressed.

  While the rotation of the fixing device 12 is stopped, the lubricant (grease oil) that has accumulated on the inner surface of the fixing belt and around the fixing nip such as the nip forming member and has increased in viscosity with natural cooling and heat radiation of the fixing device is heated, Its viscosity can be reduced. As a result, the torque peak at the start of the rotation drive of the fixing device can be reduced, and the slip between the pressure roller 30 and the fixing belt 28 due to the high torque at the start of the rotation drive can be suppressed.

  By heating the fixing belt by energizing only the heater in the central portion in the longitudinal direction, the viscosity of the lubricant in the central portion can be lowered. From the central part to the end part, the heat conduction in the member gradually causes natural heat transfer, and the lubricant viscosity at the end part can be reduced to some extent. If the lubricant viscosity at the end is significantly reduced, the lubricant may leak from the belt end, but if the lubricant viscosity is reduced only at the center part, the torque reduction effect and lubrication from the end will occur. It is possible to achieve both agent leakage.

  By the way, when the fixing belt 28 and the pressure roller 30 are arranged vertically, the lubricant applied to the inner surface of the fixing belt is likely to collect near the fixing nip SN due to the influence of gravity. Therefore, it is preferable that the heater 56 is provided inside the fixing belt so as to correspond to the fixing nip SN. As a result, the heater 56 approaches the lubricant whose viscosity has increased, and the lubricant can be heated more efficiently.

  Further, when the rotation of the fixing belt 28 is stopped, the heater 56 in the region 3 at the center in the longitudinal direction illustrated in FIGS. 5 and 6 is first heated, and then the heaters 56 in the regions 2 and 4 at the end in the longitudinal direction are heated, and then. Further, the heaters 56 in the regions 1 and 5 at the longitudinal ends may be heated. By heating the heater in this order from the central portion in the longitudinal direction toward the end portion, heat conduction in the longitudinal direction can be promoted and heat conduction from the central portion to the end portion can be carried out in a short time. More efficient and energy-saving temperature control becomes possible. The heating control from the central portion to the end portion in the longitudinal direction may be repeated not only once but also at regular intervals. By keeping the heating control while rotation is stopped so that the lubricant viscosity at each location in the longitudinal direction can be maintained at an appropriate value, problems such as high torque and slip will occur regardless of when the next paper passing job starts. It can be avoided.

  If you try to reduce the viscosity of the lubricant only with the heater in the center in the longitudinal direction around the fixing nip, it will take time for the heat conduction of each member and heat transfer between multiple members, and the viscosity of the lubricant will decrease. It also takes time. Therefore, by heating the heater in the central portion and then sequentially heating the heaters installed in the end portions, the lubricant viscosity can be lowered in a wider range in a shorter time. As a result, even when the next job comes immediately, the lubricant viscosity is reduced over a wide range, so it is possible to reduce the sliding resistance over a wide range, and to further reduce the unit torque. Is possible. At the same time, it is possible to avoid the slip phenomenon that occurs when the sliding resistance is too high.

  The number of divisions of the heating area of the heater installed in the fixing nip and the range of each divided area are not limited to those shown in FIGS. If the number of divisions is increased, the temperature of the fixing belt in the longitudinal direction can be controlled with higher accuracy, and the increase in the viscosity of the lubricant can be suppressed with higher accuracy.

  On the other hand, if all the heaters are uniformly heated while the rotation drive is stopped, the viscosity of the lubricant at both ends in the longitudinal direction will be reduced more than necessary, and the low viscosity lubricant will be removed from both ends of the fixing belt. There is a risk of leakage. As a result, the amount of lubricant tends to be insufficient, and problems such as increased sliding resistance, increased torque, and slip are likely to occur. Therefore, it is possible to prevent the viscosity of the lubricant at the end portions from being reduced more than necessary by heating with a heater only in the center portion or sequentially heating from the center portion toward the end portions. When the heater is sequentially heated from the central portion toward the end portion, the central heating region may be first heated, and the end heating region may be sequentially heated while heating the heating region. Alternatively, the central heating region may be first heated and turned off, and then the end heating region may be sequentially heated and turned off.

Next, the fixing device 12 as the second embodiment will be described based on FIG.
In the fixing device 12 according to the present embodiment, the heater 56 is composed of a thermal heater or a ceramic heater in which a resistance heating element is placed on a plate-shaped substrate. The heater 56 is disposed inside the fixing belt (fixing film) 28 and heats the temperature of the fixing belt 28 to heat and fix the unfixed image conveyed to the fixing nip SN.

  The heater 56 is arranged upstream of the fixing nip SN in the rotational direction. This is because it takes some time for the heat from the heater 56 disposed inside the fixing belt 28 to reach the surface of the fixing belt.

  As already shown in FIGS. 5 and 6, the heater 56, which is a plate-shaped heating means, has a plurality of heating regions divided in the direction orthogonal to the paper transport direction, and each heater 56 can be independently heated. It is possible. Therefore, when the rotation of the fixing belt 28 is stopped, by heating the heater 56 in the region 3 at the center in the longitudinal direction shown in FIGS. 5 and 6, it is possible to suppress the increase in the viscosity of the lubricant. The temperature of the central portion of the fixing belt 28 in the longitudinal direction is eventually conducted to both ends, and the increase in the viscosity of the lubricant at the ends can be suppressed.

  A stay 61, which is a support member, is arranged inside the fixing belt, and both ends of the stay 61 are connected to the device side plates. A pressing member 62 is installed at the fixing nip SN, and both ends of the pressing member 60 are connected to the device side plates to support the fixing belt 28.

In FIG. 8, members having the same reference numerals as the members shown in FIG. 2 have the same function as the members, and therefore the description thereof will be omitted.
The image forming apparatus is provided with the above-described fixing device 12, so that printing with higher image quality and energy saving is realized.

12 fixing device 28 fixing belt (fixing member)
30 pressure roller (pressure member)
39 Thermistor (temperature detection means)
56 Heater (heat source)
P paper (recording material)
SN fixing nip

Japanese Patent Laid-Open No. 06-95540 JP 2012-189806 A

Claims (7)

A flexible endless fixing member, a pressure member that forms a fixing nip by contact with the fixing member, and a heat source that heats the fixing member by heat conduction are provided on the recording material at the fixing nip. In the fixing device that fixes the unfixed image of
A lubricant is applied to the inner surface of the fixing member,
The heat source is a plate-shaped heating element having individually controllable heating regions divided into a plurality in the longitudinal direction of the heat source,
In order to suppress the leakage of the lubricant from the end portion in the longitudinal direction of the fixing member, the heating area at the central portion in the longitudinal direction of the heating area is first heated and then the longitudinal portion while the rotation of the fixing member is stopped. A fixing device characterized in that a heating region at an end portion in a direction is heated. The fixing nip includes a flexible endless fixing member, a pressure member that forms a fixing nip by contact with the fixing member, and a heat source that heats the fixing nip of the fixing member by heat conduction. In the fixing device that fixes the unfixed image on the recording material,
A lubricant is applied to the inner surface of the fixing member,
The heat source is a plate-shaped heating element having individually controllable heating regions divided into a plurality in the longitudinal direction of the heat source,
In order to suppress the leakage of the lubricant from the end portion in the longitudinal direction of the fixing member, the heating area at the central portion in the longitudinal direction of the heating area is first heated and then the longitudinal portion while the rotation of the fixing member is stopped. A fixing device characterized in that a heating region at an end portion in a direction is heated.   The fixing device according to claim 1, wherein the heat source is provided inside the fixing member so as to correspond to the fixing nip. A temperature detecting means for detecting the surface temperature of the pressure member,
The fixing device according to claim 1, wherein the heating control of the heat source is performed according to the temperature of the pressure member detected by the temperature detecting unit.   The fixing device according to claim 4, wherein which of the heating regions is to be heated is selected according to the temperature of the pressure member detected by the temperature detecting unit.   The fixing device according to claim 4, wherein which of the heating regions is to be heated is selected according to the temperature gradient of the pressure member detected by the temperature detecting unit.   An image forming apparatus comprising the fixing device according to claim 1.

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