JP2018156054A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to heat a desired area and control temperature by reducing energy consumption in a fixing device using a plurality of heat sources having different heat distributions (light distributions).SOLUTION: An inter-heater interference removal device 55 is provided in the subsequent stage of a temperature controller 51. A modified duty d1r obtained by subtracting a value obtained by multiplying a duty d2 of an end heater 41b by a factor α from a duty d1 of a center heater 41a is submitted to a power supply circuit 52a; at the ends, a modified duty d2r obtained by subtracting a value obtained by multiplying the duty d1 of the center heater 41a by a factor β from the duty d2 of the end heater 41b is submitted to a power supply circuit 52b; the center heater 41a and end heater 41b are caused to generate heat to heat a fixing roller 21.SELECTED DRAWING: Figure 8

Description

  The present invention relates to a fixing device that fixes an image on a recording medium and an image forming apparatus including the fixing device.

In recent years, market demands for energy saving and high speed have been increasing for image forming apparatuses such as printers, copiers, and facsimiles.
In an image forming apparatus, an unfixed toner image is transferred to a recording material sheet, printing paper, photosensitive paper, electrostatic recording paper, etc. by an image transfer method or a direct method by an image forming process such as electrophotographic recording, electrostatic recording, and magnetic recording. Formed on recording material. As a fixing device for fixing an unfixed toner image, a contact heating method fixing device such as a heat roller method, a film heating method, and an electromagnetic induction heating method is widely used.

  In image forming apparatuses such as copiers, printers, and facsimiles, toner images (unfixed toner images) formed by an image forming process such as electrophotographic recording, electrostatic recording, and magnetic recording are recorded directly or via an intermediate transfer member. The toner image is transferred onto a recording medium such as a material sheet, printing paper, photosensitive paper, or electrostatic recording paper, and the recording medium carrying the toner image is passed through a fixing device to fix the toner image on the recording medium.

  As a fixing device for fixing an unfixed toner image, a heat fixing device for fixing a toner image on a recording material (recording medium) by heat and pressure is widely used. In a typical example of such a fixing device, a fixing member and a pressure member, for example, a fixing roller and a pressure roller are brought into contact with each other with a predetermined pressure, and a toner image is formed on the contacted portion. The unfixed toner image is fixed on the sheet by the fixing and pressure roller by conveying the sheet having the sheet. A fixing roller used in such a fixing device generally includes a method in which a heater member such as a halogen lamp is housed therein and the fixing roller is uniformly heated by the heater member.

  However, in these image forming apparatuses, the size of paper conveyed for image formation is not constant. For example, sheets of various sizes such as A3 size (297 × 420 mm) to government postcard size (100 × 148 mm) are conveyed, and fixing is performed by the fixing device. At this time, in order to sufficiently fix even a large size sheet (for example, A3 size), a heater member is formed corresponding to the large size sheet and is sufficiently extended in the axial direction of the fixing roller ( For example, it is common to arrange the heater member in a state where the short side 297 mm of A3 size is sufficiently covered.

  However, as described above, when the heater member is formed in accordance with the large size paper, if the small size paper such as the postcard size or B5 size is continuously conveyed to the fixing device, the small size paper passes. The temperature of only a part falls and the problem that the temperature of another part rises more than a regulation value will arise. Therefore, a heater member having a long heating action portion and a heater member having a short heating action portion are provided for the large and small size papers to be conveyed in the axial direction of the fixing roller, respectively. There is already known a method of arranging each heater member so that the heating portion is positioned at the position where the heating is performed.

  Further, in the fixing device that uses a plurality of heating elements (heater members) depending on the paper size as described above, temperature detection means is provided at a position corresponding to each heat generation location (paper passage area). As this temperature detecting means, for example, a thermistor is adopted, and temperature control for the heater is executed from the surface temperature of the fixing roller measured by this sensor.

  However, even though the plurality of heating elements are heating elements that warm the small-size paper portion, there is a problem that the non-sheet passing portion of the small-size paper is also heated. Therefore, when the central heater is turned on to heat the central portion, the end portion is also heated, and conversely, when the end heater is heated to heat the end portion, the central portion is also heated.

  On the other hand, Patent Document 1 (Japanese Patent Application Laid-Open No. 2015-7755) has a plurality of heaters that heat the axially central portion and end portions of the fixing roller, and is provided with a movable reflective member. A fixing device that can heat only a specific portion during small-size printing is disclosed.

  In the fixing device disclosed in Patent Literature 1, the heater emits light in the portion covered with the reflecting member, but it is not used for heating the fixing member, and the problem of preventing interference between the heaters can be solved. By covering with a plate, there is energy that is not used for heating the fixing member that emits light from the heater.

  Therefore, the present invention is capable of heating a desired region in a fixing device using a plurality of heat sources having different heat distributions (light distributions) and controlling the temperature by reducing energy consumption. It is an object of the present invention to provide a fixing device and an image forming apparatus that can be used.

  In order to solve this problem, the present invention comprises a rotatable fixing member and a pressure member that is pressed against the fixing member to form a nip portion, and carries a non-fixed toner image in the nip portion. And a second heat source for heating an axial end portion of the fixing member in a fixing device for fixing an unfixed toner image on a recording material by passing the toner image. And first temperature detecting means for detecting the temperature of the axially central portion of the fixing member, and second temperature detecting means for detecting the temperature of the axial end portion of the fixing member, The present invention is characterized in that an apparatus for removing interference between heat sources that removes interference between heat sources is provided.

  The lighting of the first heat source that heats the axial central portion of the fixing member and the second heat source that heats the axial end portion can be effectively used for central heating and end heating of the fixing member. For this reason, it is possible to efficiently heat a desired region and realize heat source control without consuming wasteful power.

1 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. 1 is a schematic cross-sectional view of a fixing device according to a first embodiment. It is a figure which shows arrangement | positioning of the several heater which a fixing device has. It is a schematic diagram which shows the example of heat distribution of each heater. 6 is a graph showing a temperature rise state of the fixing roller when the apparatus is started up. It is a schematic diagram explaining a heater duty. FIG. 6 is a diagram illustrating an example of temperature rise at the center and the end in the fixing roller axial direction when a plurality of heaters in the embodiment are independently lit (heated). It is a control block diagram which shows the characteristic structure of this invention. It is a schematic sectional drawing which shows the fixing device of 2nd Embodiment.

  The fixing device according to the present invention has a heating element (heater) that is a plurality of heat sources, and is capable of removing interference by providing an inter-heater interference removing device that removes interference between heating portions between the heaters. It is said. The features of the present invention will be described in detail below.

In the present invention, the heater duty of the central heater and the end heater as heating elements for heating the fixing member (the heater lighting time ratio per unit time is defined as a heat generation rate), the temperature rising gradient at the center of the fixing member, and the end By formulating the relationship of the temperature rise gradient and relating it in a 2 * 2 matrix,
(Central heating ramp) = (A11 A12) (Central heater duty)
(End temperature ramp) (A21 A22) (End heater duty) (Equation 1)
For the relationship
Center heater duty correction value = (center heater duty)-(edge heater duty) * coefficient α
End heater duty correction value = (end heater duty) − (center heater duty) * coefficient β (Expression 2)
Can be set such that A12 = A21 = 0 in equation (1), and the relationship as in equation (3) can be obtained.
(Central heating ramp) = (A11 0) (Central heater duty)
(End temperature ramp) (0 A22) (End heater duty) (Equation 3)
In addition, since each numerical formula is described here in a simulated manner as a character, the accurate mathematical formula is inserted as an image in the embodiment.

  With such a setting, the relation between the charging duty of the central heater and the central ascending / descending gradient becomes a proportional relation, and the relation between the charging duty of the end heater and the end temperature rising gradient can be made proportional.

  Thus, when it is desired to heat the center of the fixing member, only the central heater is turned on at a high heater duty, and when it is desired to heat the end of the fixing member, only the end heater is turned on at a high heater duty. The lighting of the heater and the end heater can be effectively used for heating the center portion and the end portion of the fixing member. Therefore, it is possible to control the heater of the fixing device that can heat a desired region and does not consume useless power.

Hereinafter, embodiments will be described with reference to the drawings.
FIG. 1 is a cross-sectional configuration diagram illustrating an example of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 1 shown in this figure is a tandem type color printer in which image forming units for forming a plurality of color images are juxtaposed along the belt extending direction. However, the present invention is not limited to this method, and can be applied not only to a printer but also to a copying machine, a facsimile machine, and the like.

  Four bottles 102Y, 102M, 102C, and 102K corresponding to the respective colors (yellow, magenta, cyan, and black) are detachably (replaceable) installed in the bottle housing portion 101 above the image forming apparatus main body. Yes.

An intermediate transfer unit 85 is disposed below the bottle housing portion 101.
Image forming units 4Y, 4M, 4C, and 4K corresponding to the respective colors (yellow, magenta, cyan, and black) are arranged in parallel so as to face the intermediate transfer belt 78 of the intermediate transfer unit 85. Photosensitive drums 5Y, 5M, 5C, and 5K are disposed in the image forming units 4Y, 4M, 4C, and 4K, respectively.

  Further, around each of the photosensitive drums 5Y, 5M, 5C, and 5K, a charging unit 75, a developing unit 76, a cleaning unit 77, a charge eliminating unit, and the like are disposed. Then, an image forming process (charging process, exposure process, development process, transfer process, cleaning process) is performed on each of the photoconductive drums 5Y, 5M, 5C, and 5K. An image of each color is formed on 5K.

  The photosensitive drums 5Y, 5M, 5C, and 5K are rotationally driven in the clockwise direction in FIG. 1 by a drive motor. Then, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K are uniformly charged at the position of the charging unit 75 (charging process).

  Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach the irradiation position of the laser light L emitted from the exposure unit 3, and electrostatic latent images corresponding to the respective colors are formed by exposure scanning at this position. (Exposure process).

  Thereafter, the surfaces of the photosensitive drums 5Y, 5M, 5C, and 5K reach a position facing the developing device 76, and the electrostatic latent image is developed at this position to form toner images of each color (developing process). ). Thereafter, the surfaces of the photoconductive drums 5Y, 5M, 5C, and 5K reach the positions facing the intermediate transfer belt 78 and the first transfer bias rollers 79Y, 79M, 79C, and 79K, and at these positions, the photoconductive drums 5Y, 5M. The toner images on 5C and 5K are transferred onto the intermediate transfer belt 78 (primary transfer step). At this time, a small amount of untransferred toner remains on the photosensitive drums 5Y, 5M, 5C, and 5K.

  Thereafter, the surfaces of the photoconductive drums 5Y, 5M, 5C, and 5K reach a position facing the cleaning unit 77, and untransferred toner remaining on the photoconductive drums 5Y, 5M, 5C, and 5K is removed at this position. It is mechanically recovered by a cleaning blade 77 (cleaning process).

  Finally, the surfaces of the photoconductive drums 5Y, 5M, 5C, and 5K reach a position facing the charge eliminating unit, and the residual potential on the photoconductive drums 5Y, 5M, 5C, and 5K is removed at this position. Thus, a series of image forming processes performed on the photosensitive drums 5Y, 5M, 5C, and 5K is completed. Thereafter, the toner images of the respective colors formed on the respective photosensitive drums through the developing process are transferred onto the intermediate transfer belt 78 in an overlapping manner. In this way, a color image is formed on the intermediate transfer belt 78.

  Here, the intermediate transfer unit 85 includes an intermediate transfer belt 78, four primary transfer bias rollers 79Y, 79M, 79C, and 79K, a secondary transfer backup roller 82, a cleaning backup roller 83, a tension roller 84, and an intermediate transfer cleaning unit 80. , Etc. The intermediate transfer belt 78 is stretched and supported by three rollers 82 to 84, and is moved endlessly in the direction of the arrow in the figure (counterclockwise in the figure) by the rotational drive of one roller 82.

  The four primary transfer bias rollers 79Y, 79M, 79C, and 79K sandwich the intermediate transfer belt 78 with the photosensitive drums 5Y, 5M, 5C, and 5K, respectively, thereby forming primary transfer nips. Then, a transfer bias reverse to the polarity of the toner is applied to the primary transfer bias rollers 79Y, 79M, 79C, and 79K. The intermediate transfer belt 78 travels in the direction of the arrow and sequentially passes through the primary transfer nips of the primary transfer bias rollers 79Y, 79M, 79C, and 79K. In this way, the toner images of the respective colors on the photosensitive drums 5Y, 5M, 5C, and 5K are primarily transferred while being superimposed on the intermediate transfer belt 78.

  Thereafter, the intermediate transfer belt 78 onto which the toner images of the respective colors are transferred in an overlapping manner reaches a position facing the secondary transfer roller 89. At this position, the secondary transfer backup roller 82 sandwiches the intermediate transfer belt 78 between the secondary transfer roller 89 and forms a secondary transfer nip. The four color toner images formed on the intermediate transfer belt 78 are transferred onto the recording medium P conveyed to the position of the secondary transfer nip. At this time, untransferred toner that has not been transferred to the recording medium P remains on the intermediate transfer belt 78. Thereafter, the intermediate transfer belt 78 reaches the position of the intermediate transfer cleaning unit 80. At this position, the untransferred toner on the intermediate transfer belt 78 is collected.

Thus, a series of transfer processes performed on the intermediate transfer belt 78 is completed.
Here, the recording medium P transported to the position of the secondary transfer nip is transported from the paper feeding unit 12 disposed below the apparatus main body 1 via the paper feeding roller 97 and the registration roller pair 98. It is a thing.

  Specifically, a plurality of recording media P such as transfer paper are stored in the paper supply unit 12 in an overlapping manner. When the paper feed roller 97 is rotated counterclockwise in FIG. 3, the uppermost recording medium P is fed between the rollers of the registration roller pair 98. The recording medium P conveyed to the registration roller pair 98 is temporarily stopped at the position of the roller nip of the registration roller pair 98 that has stopped rotating. Then, the registration roller pair 98 is rotationally driven in synchronization with the color image on the intermediate transfer belt 78, and the recording medium P is conveyed toward the secondary transfer nip. In this way, a desired color image is transferred onto the recording medium P.

  Thereafter, the recording medium P on which the color image is transferred at the position of the secondary transfer nip is conveyed to the position of the fixing device 20. At this position, the color image transferred to the surface is fixed on the recording medium P by heat and pressure generated by the fixing member 21 and the pressure member 31. Thereafter, the recording medium P is discharged out of the apparatus through a pair of paper discharge rollers 99. The recording medium P discharged out of the apparatus by the discharge roller pair 99 is sequentially stacked on the stack unit 100 as an output image. Thus, a series of image forming processes in the image forming apparatus is completed.

FIG. 2 is a cross-sectional view illustrating a configuration example of the fixing device. The present invention is not limited to this method, and an appropriate configuration such as a belt fixing device can be employed.
The fixing device 20 illustrated in FIG. 2 includes a fixing member 21 and a pressure member 31 that is pressed against the fixing member 21. In this example, the pressure roller 31 is in pressure contact with the fixing roller 21 having a heat source 41 therein.

  The fixing roller 21 includes a base material 21b and a surface layer 21a. The base material 21b is a metal such as iron or aluminum. The surface layer 21a is provided with a release layer such as PFA on a thin elastic member such as silicone rubber. . The surface layer 21a of the fixing roller 21 may be configured such that a release layer such as PFA is directly coated on the base material 21b. In order to save energy, the base material 21b of the fixing roller 21 is configured with a thin thickness of about 0.3 to 0.7 mm.

  The pressure roller 31 of the pressure member is also composed of a base material 31b and an elastic layer 31a. The base material 31b is made of a metal such as iron, and the elastic layer 31a is made of silicone rubber or sponge. Similar to the roller, a release layer such as PFA is provided.

  A nip portion N is formed between the fixing roller 21 and the pressure roller 31. By passing the transfer paper on which the toner image is formed in the nip portion N, the toner adhering to the transfer paper is removed. It is melted by heat and attached to transfer paper by pressurization.

FIG. 3 is a diagram illustrating an arrangement of a plurality of heaters included in the fixing device.
In the fixing device 20 of this example, two halogen heaters as heat sources 41 are arranged inside the fixing roller 21. One is a heater 41a (first heater) that mainly heats the central portion of the paper passing area, and the other is a heater 41b (second heater) that mainly heats the end of the paper passing area.

  An example of the heat distribution of each heater is shown in FIG. The first heater 41a is configured such that the center portion has a heat distribution peak with respect to the maximum sheet width. For example, the winding of the filament is adjusted so that the width of this peak corresponds to, for example, the width of an A5 size paper. The second heater 41b is configured so that both ends thereof have a heat distribution peak with respect to the maximum sheet width. The central portion of the second heater 41b adjusts the winding of the filament so that about 20% of the rated power is applied.

  FIG. 4 is a schematic diagram showing the heat distribution of the halogen heater. Since the halogen heater heater as the heat source 41 has such a configuration, the first heater 41a heats the center of the sheet (in this example, the center in the width direction of the sheet conveyed with the center reference), and the second heater 41b has a role of heating the end of the paper, but the first heater 41a also has filament winding at the end (the filament winding is shown by cross-hatching in the figure), so that the first heater 41a is heated. Thus, the temperature rise is also observed at the end portion, and by heating the second heater 41b, the center is also heated by the filament winding at the center portion of the second heater.

  The reason for providing a plurality of heaters is that only the first heater 41a (also referred to as a central heater) is used when printing on a paper with a small paper width (small size paper). At the time of printing, the second heater 41b (also referred to as an end heater) is used in combination with the first heater 41a (center heater) to give a heat amount capable of fixing the toner to the sheet over the entire width of the sheet.

  FIG. 5 is a graph showing a temperature rising state of the fixing roller when the apparatus is started up (at the start of use in the morning). The temperature rise of the fixing roller may be different between the central portion and the end portion. In the graph of FIG. 5, the temperature rising gradient at the axial center of the fixing roller 21 is shown as “central temperature rising gradient: dT1 / dt”, and the temperature rising gradient at the end in the axial direction is “edge temperature rising gradient: dT2 //”. dt ".

  FIG. 6 is a schematic diagram for explaining the heater duty representing the heater lighting rate. A percentage of the heater ON time ratio (heater on time / control cycle) with respect to the control cycle for performing heater control is referred to as heater duty.

  In the fixing device of the embodiment, when the plurality of heaters having the heat distribution shown in FIG. 4 are lit (heated) independently, the temperature rises at the center and the end in the fixing member longitudinal direction (fixing roller axial direction). An example is shown in FIG.

  FIG. 7A shows the lighting duty of the first heater 41a (center heater) and the second heater 41b (end heater), and the temperature rise gradient at the center and end in the axial direction under each condition. FIG. 7B shows the rate contributing to the temperature increase gradient of the first heater 41a (center heater) and the second heater 41b (end heater).

  Test condition A shows a central temperature rise gradient and an end temperature rise gradient when the center heater duty is 100% and the end heater duty is 100%. Test condition B is lit only at the center heater with a heater duty of 100%. The end heater shows a central temperature rising gradient and an end temperature rising gradient at a duty of 0% (non-lighting).

Test condition C indicates the central temperature rise gradient and the end temperature rise gradient when only the end heater is turned on with a heater duty of 100% and the central heater is not turned on.
The sum of the temperature increase gradients of test condition B and test condition C is the temperature increase gradient of test condition A, and both the central heater and the end heater are turned on to accelerate the temperature increase at startup. . The contribution of the central heater and the end heater to the temperature gradient at the center and the end is as shown in FIG. 7B. In this example, the central heater contributes about 79% to the center temperature increase. However, it can be seen that the end heater contributes about 50% to the end temperature increase.

This also leads to the fact that the conventional fixing device consumes a large amount of energy because it cannot be controlled independently when it is desired to heat only the center.
The following formula (formula 1) is formulated from the result of FIG.

This is shown in the control block diagram in FIG.
Based on the difference between the target temperature at the center and end in the axial direction and the detected temperature at the center and end, the heater duty required by the temperature controller (PID control, etc.) is calculated for each of the center and end.

  Conventionally, the power supply circuit is driven with the heater duty calculated as described above to turn on the heater to obtain the temperature rise gradient at the center and end, and the center and end detection temperatures are obtained as integral amounts. It has been.

On the other hand, in the present invention, the inter-heater interference removing device 55 is provided downstream of the temperature controller 51.
Here, the inter-heater interference removing device inputs a corrected duty d1r obtained by subtracting a value obtained by multiplying the duty d1 of the central heater 41a by the duty d2 of the end heater 41b to the coefficient α to the power supply circuit 52a. In this device, the power supply circuit 52b is supplied with a corrected duty d2r obtained by subtracting a value obtained by multiplying the duty d2 of the end heater 41b by the coefficient β of the duty d1 of the central heater 41a.

  In the embodiment, the center and end temperature in the axial direction of the fixing roller 21 are detected by the temperature sensors 45 and 46. Further, the temperature rising gradients at the center and at the end of the fixing roller 21 are integrated by integrators 53a and 53b to obtain detected temperatures at the center and at the end, respectively. The detected temperature is fed back.

The configuration of the inter-heater interference removal apparatus is shown in the following formula (Formula 2).

The following formula (Formula 3) is formulated by putting Formula 2 into the central heater duty term of Formula 1.

From this, the relationship between the temperature gradient at the center and the end and the duties d1 and d2 is expressed by coefficients including α and β.
Therefore, in order to set the interference term to 0, the interference can be removed by selecting the values of α and β in the following equation (Equation 4), and the heater duty without interference as in the following equation (Equation 5) A temperature ramp relationship is obtained.

In addition, the structure of the inter-heater interference removal apparatus in this embodiment is as shown in FIG.
Incidentally, in the example of FIG.
A11 = 0.172, A12 = 0.057, A21 = 0.044, A22 = 0.058
α = 0.33 and β = 0.759.

  In the image forming apparatus according to the present exemplary embodiment, by applying the interference removal between the heaters as described above at the time of printing, it is possible to fix the paper width without wasteful power consumption. In particular, enabling at the time of printing is effective in reducing energy consumption. That is, in a fixing device using a plurality of heat sources having different heat distributions (light distributions), a desired region can be heated, and temperature control can be performed while reducing energy consumption.

FIG. 9 is a cross-sectional configuration diagram showing an embodiment of a belt fixing device using a fixing belt as a fixing member.
The fixing device 120 includes a fixing belt 121 as a rotatable fixing member, and a pressure roller 131 as a pressure member that is disposed opposite to the fixing belt 121 and is rotatable, and includes halogen heaters 141a and 141b as a plurality of heat sources. As a result, the fixing belt 121 is directly heated by radiant heat from the inner peripheral side. At this time, in the loop of the fixing belt 121, there is a nip forming member 124 that forms a nip portion with the pressure roller 131 via the fixing belt 121, and directly on the inner surface of the fixing belt or through the sliding sheet 127. It is designed to slide indirectly. The recording medium P that has passed through the secondary transfer roller is conveyed in the direction of the arrow in the figure, and the toner image on the recording medium P is fixed at the nip portion N by heating and pressing.

  Although the shape of the nip portion is flat in FIG. 9, it may be a concave shape or other shapes. In the case of the concave nip portion, the discharge direction of the leading end of the recording material is closer to the pressure roller, and the separation is improved, so that the occurrence of jam is suppressed.

  The fixing belt 121 is constituted by an endless belt or a film using a metal material such as nickel or SUS or a resin material such as polyimide. The surface layer of the belt has a release layer such as a PFA or PTFE layer, and has a release property so that toner does not adhere. There may be an elastic layer formed of a silicone rubber layer or the like between the belt substrate and the PFA or PTFE layer. When there is no silicone rubber layer, the heat capacity is reduced and the fixability is improved, but when the unfixed image is crushed and fixed, minute irregularities on the belt surface are transferred to the image, and the image has a crusty skin shape. There may be a problem that the gloss unevenness (skin skin image) remains. In order to improve this, it is necessary to provide a silicone rubber layer of 100 [μm] or more. Due to the deformation of the silicone rubber layer, fine irregularities are absorbed and the skin image is improved.

  A stay 125 as a supporting member for supporting the nip forming member 124 and the nip portion N is provided in the loop of the fixing belt 121 to prevent the nip forming member 124 that receives pressure from the pressure roller 131 from being bent, and in the axial direction. So that a uniform nip width can be obtained. The stay 125 is held and fixed and positioned on flanges as holding members at both ends. In addition, reflection members 128a and 128b are provided between the halogen heaters 141a and 141b and the stay 125, and wasteful energy consumption due to the stay 125 being heated by radiation heat from the halogen heaters 141a and 141b is suppressed. Here, instead of providing the reflecting member 128, the same effect can be obtained even if the surface of the stay 125 is heat-insulated or mirror-finished.

  The pressure roller 131 has an elastic rubber layer on the core metal, and a release layer (PFA or PTFE layer) is provided on the surface in order to obtain releasability. The pressure roller 131 is rotated by a driving force transmitted from a driving source such as a motor provided in the image forming apparatus via a gear. The pressure roller 131 is pressed against the fixing belt 121 by a spring or the like, and has a predetermined nip width as a result of the elastic rubber layer being crushed and deformed. The pressure roller 131 may be a hollow roller, and the pressure roller 131 may have a heating source such as a halogen heater. The elastic rubber layer may be solid rubber, but if there is no heater inside the pressure roller 131, sponge rubber may be used. Sponge rubber is more desirable because it increases heat insulation and makes it difficult for the fixing belt to lose heat.

  The fixing belt 121 is rotated by the pressure roller 131. In the case of FIG. 9, the pressure roller 131 is rotated by the driving source, and the driving force is transmitted to the belt at the nip portion N, whereby the fixing belt 121 rotates. The fixing belt 121 is sandwiched and rotated at the nip portion N, and travels while being guided by the flanges at both ends other than the nip portion.

  In this fixing device, the halogen heater 141a is a first heater (center heater), and the halogen heater 141b is a second heater (end heater). The first heater (center heater) and the second heater (end heater) 141b have the same heat distribution as the first heater (center heater) 41a and the second heater (end heater) 41b in the fixing device 20 of FIG. The filament winding of each heater is set so that

  In addition, a temperature sensor 145 that detects the temperature of the central portion of the fixing belt 121 in the axial direction and a temperature sensor 146 that detects the temperature of the end portion of the fixing belt 121 in the axial direction are provided. In this example, the temperature sensor 145 is in contact with or close to the fixing belt 121 such that the temperature sensor 145 faces the first heater (center heater) 141a and the temperature sensor 146 faces the second heater (end heater) 141b. Are arranged. In this example, the temperature sensor 145 that detects the temperature at the center uses a thermopile, and the temperature sensor 146 that detects the temperature at the end uses a contact thermistor. Since the belt-type fixing device has a higher temperature rise than the roller configuration, it is desirable that the center portion be a thermopile and the end portion be a contact thermistor.

  Then, the inter-heater interference removing device 55 is provided in the same manner as the fixing device 20 in FIG. 2, and the interference removal between the heaters as described in FIG. An effect can be obtained. That is, in a fixing device using a plurality of heat sources having different heat distributions (light distributions), a desired region can be heated and temperature control can be performed while reducing energy consumption.

  As mentioned above, although this invention was demonstrated based on the example of illustration, this invention is not limited to this. For example, the heat source of the fixing device is not limited to the halogen heater, and an appropriate heat source can be adopted as long as the present invention can be applied. The present invention can also be applied to a configuration including three or more heat sources each having a different heat distribution.

  As the image forming apparatus, any configuration can be adopted as long as the present invention is applicable. The image forming apparatus is not limited to a printer, and may be a copying machine, a facsimile machine, or a multifunction machine having a plurality of functions.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 4 Image forming part 5 Photosensitive drum 20 Fixing apparatus 21 Fixing roller (fixing member)
31 Pressure roller (Pressure member)
41 Halogen heater (heat source)
41a First heater (central heater)
41b Second heater (end heater)
45, 46 Temperature sensor (temperature detection means)
REFERENCE SIGNS LIST 51 Temperature controller 52 Power supply circuit 53 Integrator 55 Interference heater removing device 120 Fixing device 121 Fixing belt
124 Nip forming member 131 Pressure roller (Pressure member)
141 Halogen heater (heat source)
141a First heater (central heater)
141b Second heater (end heater)
145, 146 Temperature sensor (temperature detection means)
P paper (recording medium, recording material)
N Fixing nip

Japanese Patent Laying-Open No. 2015-7755

Claims (7)

A rotation fixing member; and a pressure member that is pressed against the fixing member to form a nip portion. The recording material carrying an unfixed toner image is passed through the nip portion to pass the unfixed toner image to the recording material. In a fixing device that fixes to
A first heat source for heating an axially central portion of the fixing member;
A second heat source for heating the axial end of the fixing member;
First temperature detecting means for detecting the temperature of the axially central portion of the fixing member;
Second temperature detection means for detecting the temperature of the axial end of the fixing member;
Have
A fixing device comprising a heat source interference removing device for removing interference between the heat sources. The interference canceling apparatus between heat sources is
Deviation between the target temperature in the axial center when heating the fixing member and the temperature detected by the first temperature detecting means, the target temperature in the axial direction when heating the fixing member, and the detected temperature by the second temperature detecting means And calculating the heating rate of the first heat source and the heating rate of the second heat source based on the deviation of
A value obtained by multiplying the heat generation rate of the second heat source by a predetermined coefficient is subtracted from the calculated heat generation rate of the first heat source, and the first heat source is calculated from the calculated heat generation rate of the second heat source. A process of subtracting a value obtained by multiplying the heat generation rate of the heat source by a predetermined coefficient,
The fixing device according to claim 1, wherein the heat generation rate of the first heat source and the heat generation rate of the second heat source are corrected. The interference canceling apparatus between heat sources is
Temperature rise gradient of the first heat source = A11 × first heat source heat generation rate + A12 × second heat source heat generation rate Temperature rise gradient of the second heat source = A21 × first heat source heat generation rate + A22 × first When the heat generation rate of the second heat source
Heating rate correction value of the first heat source = (heating rate of the first heat source) − (heating rate of the second heat source) × (A12 / A11)
Heating rate correction value of the second heat source = (heating rate of the second heat source) − (heating rate of the first heat source) × (A21 / A22)
The fixing device according to claim 2, wherein:   The fixing device according to claim 1, wherein the interference removal by the interference removal device between heat sources is performed during a fixing operation.   The fixing device according to claim 1, wherein the heat source is a halogen heater.   6. The fixing device according to claim 1, wherein the fixing member is a fixing belt, the first temperature detecting means is a thermopile, and the second temperature detecting means is a thermistor disposed in contact with the fixing member. The fixing device according to claim 1. An image forming apparatus comprising the fixing device according to claim 1.

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