JP7354857B2 - Fixing device and image forming device - Google Patents

Description

The present invention relates to a fixing device and an image forming apparatus.

Conventionally, in image forming apparatuses such as printers, copiers, facsimile machines, and multifunction devices, such as electrophotographic printers, the main body of the printer, that is, the main body of the apparatus, includes an image forming unit, an LED head, a transfer unit, and a fixing device. The image forming unit is provided with a photosensitive drum, a charging roller, a developing roller, a supply roller, a toner cartridge, and the like.

In the image forming unit, the surface of the photosensitive drum uniformly charged by the charging roller is exposed to light by the LED head to form an electrostatic latent image, and toner is attached to the electrostatic latent image by the developing roller. The toner image is transferred onto a sheet of paper as a medium by a transfer unit, and is fixed in a fixing device to form an image and printing is performed.

By the way, as a fixing device, a heater is disposed inside the fixing belt, and the fixing belt is heated by the heater, and the toner image is heated and pressurized in the nip formed between the fixing belt and the backup roller. A belt-heating type fixing device for fixing to paper has been provided (for example, see Patent Document 1).

Japanese Patent Application Publication No. 2018-138937

However, in the conventional fixing device, the fixing belt is not heated uniformly, and the toner image cannot be properly fixed on the paper, resulting in a decrease in image quality.

FIG. 2 is a conceptual diagram showing the fixing device in a conventional pressurized state, and FIG. 3 is a conceptual diagram showing the fixing device in a conventional released state.

In the figure, 18 is a belt heating type fixing device, 21 is a belt unit, 22 is a backup roller, 51 is an endless fixing belt, and 53 is a heater unit disposed within the fixing belt 51.

The heater unit 53 includes a frame Fr1, a heater Ht1 disposed within the frame Fr1 to heat the fixing belt 51, and a heater Ht1 disposed between the heater Ht1 and the fixing belt 51 to heat the heat generated by the heater Ht1. The fixing device includes a heat diffusion member 55 that diffuses heat and heats the fixing belt 51, a holder Fd1 that holds the heater Ht1 and the heat diffusion member 55 to the frame Fr1, and the like. In order to efficiently transfer the heat of the heater Ht1 to the heat diffusion member 55, grease is applied to the surface of the heat diffusion member 55.

In the pressurized state of the fixing device 18 where fixing is performed, the frame Fr1 is moved downward by the biasing forces of springs sp1 and sp2 disposed at both ends of the frame Fr1, and the heater unit 53 is moved through the fixing belt 51. When the paper is pressed against the backup roller 22 and current is supplied to the heater Ht1 via the connector 57, the toner image on the paper is heated and heated in the nip formed between the fixing belt 51 and the backup roller 22. It is pressed and fixed to the paper.

On the other hand, in a released state of the fixing device 18 where fixing is not performed, the frame Fr1 is moved upward by a mechanism such as a cam (not shown) against the urging force of the springs sp1 and sp2. At this time, if the clearance CL between the heater Ht1 and the heat diffusion member 55 varies due to manufacturing errors in the locking parts En1 and En2 between the holder Fd1 and the heat diffusion member 55, the grease application state may be uneven. It will happen.

As a result, when the fixing device 18 is placed in a pressurized state and current is supplied to the heater Ht1, the fixing belt 51 is not heated uniformly, making it impossible to properly fix the toner image on the paper. The quality will deteriorate.

An object of the present invention is to provide a fixing device and an image forming device that can solve the problems of the conventional fixing device 18, fix a developer image well on a medium, and improve image quality. With the goal.

For this purpose, the fixing device of the present invention includes first and second fixing members, and in a pressurized state, the medium is held between the first and second fixing members by the biasing force of the first biasing member. The developer image on the medium is fixed, and in the released state, the first and second fixing members are separated.

The first fixing member includes an endless fixing belt movably disposed opposite to the second fixing member, and a heating unit disposed within the fixing belt to heat the fixing belt. Be prepared.

The heating unit also includes a heating member, a heat diffusion member disposed between the heating member and the fixing belt and configured to diffuse heat generated by the heating member, and a heat diffusion member disposed between the heating member and the heat diffusion member. A heat transfer promoter is disposed to promote heat transfer, and a second biasing member biases the heat diffusion member toward the heating member by a biasing force in the released state.

According to the present invention, the fixing device includes the first and second fixing members, and in a pressurized state, the medium is held between the first and second fixing members by the biasing force of the first biasing member. The developer image on the medium is fixed, and in the released state, the first and second fixing members are separated.

The first fixing member includes an endless fixing belt movably disposed opposite to the second fixing member, and a heating unit disposed within the fixing belt to heat the fixing belt. Be prepared.

The heating unit also includes a heating member, a heat diffusion member disposed between the heating member and the fixing belt and configured to diffuse heat generated by the heating member, and a heat diffusion member disposed between the heating member and the heat diffusion member. A heat transfer promoter is disposed to promote heat transfer, and a second biasing member biases the heat diffusion member toward the heating member by a biasing force in the released state.

In this case, when the fixing device is in the released state, the heat diffusion member is urged toward the heating member by the urging force of the second urging member and brought into close contact with the heating member, so that the heat diffusion member is disposed between the heating member and the heat diffusion member. It is possible to prevent unevenness from occurring in the applied state of the heat transfer promoter.

Therefore, when the fixing device is placed under pressure and current is supplied to the heating member, the fixing belt can be heated uniformly, so the developer image can be well fixed on the medium, and the image Quality can be improved.

FIG. 3 is a conceptual diagram showing the fixing device in a released state according to the first embodiment of the present invention. FIG. 2 is a conceptual diagram showing a fixing device in a conventional pressurized state. FIG. 2 is a conceptual diagram showing a conventional fixing device in a released state. FIG. 1 is a conceptual diagram of a printer according to a first embodiment of the present invention. FIG. 2 is a perspective view of the fixing device according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view showing the fixing device in a pressurized state according to the first embodiment of the present invention. FIG. 3 is a longitudinal cross-sectional view showing the fixing device in a pressurized state according to the first embodiment of the present invention. FIG. 2 is a perspective view of a main part of the fixing device in a pressurized state according to the first embodiment of the present invention. FIG. 2 is a first enlarged view of essential parts showing the fixing device in a pressurized state according to the first embodiment of the present invention. FIG. 7 is a second enlarged view of main parts showing the fixing device in a pressurized state according to the first embodiment of the present invention. FIG. 3 is a cross-sectional view showing the fixing device in a released state according to the first embodiment of the present invention. FIG. 3 is a longitudinal cross-sectional view showing the fixing device in a released state according to the first embodiment of the present invention. FIG. 3 is a first enlarged view of essential parts showing the fixing device in a released state according to the first embodiment of the present invention. FIG. 7 is a second enlarged view of main parts showing the fixing device in a released state according to the first embodiment of the present invention. FIG. 7 is a conceptual diagram showing a fixing device in a pressurized state according to a second embodiment of the present invention. FIG. 7 is a conceptual diagram showing a fixing device in a released state according to a second embodiment of the present invention. FIG. 7 is a conceptual diagram showing a fixing device in a released state according to a third embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, a fixing device as a fixing device and a printer as an image forming device will be described.

In each figure, the x-axis positive direction is the opposite direction to the paper P transport direction, the x-axis negative direction is the paper P transport direction, and the y-axis positive direction is when viewed from the upstream side in the paper P transport direction. The right direction, the y-axis negative direction is the left direction when viewed from the upstream side in the conveyance direction of the paper P, and the z-axis positive direction is the height direction of the printer 10.

FIG. 4 is a conceptual diagram of a printer in the first embodiment of the present invention.

In the figure, 10 is the printer, Bd is the main body of the printer 10, that is, the main body of the printer, Cs is the casing of the printer 10, and a paper cassette 11 as a medium storage section is disposed at the bottom of the casing Cs. Paper P as a medium is loaded in the paper cassette 11. A paper feeding mechanism 12 is disposed adjacent to the front end of the paper feeding cassette 11.

The paper feed mechanism 12 includes a hopping roller (not shown) that feeds out the uppermost sheet P in the paper cassette 11, a paper feed roller 13 that feeds the fed sheet P to a paper transport path Rt1 as a medium transport path, and It consists of a separation member 14 that is disposed to face the paper feed roller 13 and prevents double feeding of paper P.

A pair of registration rollers m1 is provided on the downstream side of the paper feeding mechanism 12 in the paper transport path Rt1, and an image forming section Q1 is provided on the downstream side of the pair of registration rollers m1.

The image forming section Q1 includes image forming units 16Bk, 16Y, 16M, and 16C of black, yellow, magenta, and cyan, each of which is detachably attached to the apparatus main body Bd, and each image forming unit 16Bk, 16Y. , 16M, and 16C, and an LED head (not shown) as an exposure device.

Each of the image forming units 16Bk, 16Y, 16M, and 16C includes a photosensitive drum 31 as an image carrier, a charging roller 32 as a charging device, a developing device 33, a toner cartridge 34 as a developer storage section, and a cleaning member as a cleaning member. A cleaning blade 35 and the like are provided, and a toner cartridge 34 stores toner as a developer. Furthermore, the LED head is disposed above each photoreceptor drum 31 so as to face the photoreceptor drum 31 .

The transfer unit u1 includes a driving roller r1 as a first rotating roller, a driven roller r2 as a second rotating roller, and a belt member stretched between the driving roller r1 and the driven roller r2 so as to run freely. A transfer belt 17, and a transfer roller (not shown) as a transfer member, which is rotatably disposed facing each of the photoreceptor drums 31 with the transfer belt 17 in between, and forms a transfer portion between the transfer belt 17 and the photoreceptor drums 31. Equipped with

A fixing device 18 is disposed downstream of the image forming section Q1 in the paper transport path Rt1. In the present embodiment, the fixing device 18 is a belt heating type fixing device, and includes a belt unit 21 as a first fixing member and a backup roller 22 as a second fixing member in the housing Hs. . In the pressurized state, the paper P is held between the belt unit 21 and the backup roller 22, a nip portion is formed between the belt unit 21 and the backup roller 22, and in the released state, the belt unit 21 and the backup roller 22 are separated. I am made to do so.

A conveyance roller 37 is disposed downstream of the fixing device 18 in the paper conveyance path Rt1, and a discharge roller 38 is disposed downstream of the conveyance roller 37.

Note that in this embodiment, the photoreceptor drum 31 is used as the image carrier, but a belt-shaped photoreceptor may also be used.

Next, the operation of the printer 10 will be explained.

When a print command is sent to the printer 10 from a host computer (not shown) serving as a host device, the topmost paper P in the paper cassette 11 is fed out by the hopping roller and separated one by one by the paper feed mechanism 12. The paper is fed to the paper transport path Rt1, transported by a pair of registration rollers m1, and supplied to the image forming section Q1.

In the image forming section Q1, the surface of the photoreceptor drum 31 of each image forming unit 16Bk, 16Y, 16M, 16C is uniformly charged by the charging roller 32 and exposed to light by the LED head. An electrostatic latent image is formed as a latent image, and the electrostatic latent image is developed by the developing device 33 to form a toner image as a developer image.

The paper P supplied to the image forming section Q1 is conveyed as the transfer belt 17 runs, passes between each photoreceptor drum 31 and each transfer roller, and at this time, the paper P is transferred by each transfer roller. , the toner images of each color formed on each photoreceptor drum 31 in each of the image forming units 16Bk, 16Y, 16M, and 16C are sequentially transferred onto the paper P in an overlapping manner to form a color toner image. Toner remaining after the toner image is transferred on each photosensitive drum 31 is scraped off by a cleaning blade 35 , and the photosensitive drum 31 after the toner has been scraped off is charged again by a charging roller 32 .

The paper P on which the color toner image has been formed is sent to the fixing device 18. At this time, the fixing device 18 is placed in a pressurized state, and the color toner image on the paper P is heated and pressurized at the nip portion to be fixed on the paper P, forming a color image on the paper P. .

The paper P discharged from the fixing device 18 is conveyed by the conveyance roller 37, and then discharged to the outside of the apparatus main body Bd by the discharge roller 38, and is stacked on the stacker St1.

Next, the fixing device 18 will be explained.

FIG. 1 is a conceptual diagram showing the fixing device in the released state according to the first embodiment of the present invention, FIG. 5 is a perspective view of the fixing device according to the first embodiment of the present invention, and FIG. 7 is a cross-sectional view showing the fixing device in a pressurized state according to the first embodiment of the present invention, and FIG. 7 is a cross-sectional view showing the fixing device in a pressurized state in the first embodiment of the present invention. FIG. 8 is a perspective view of a main part of the fixing device when it is placed in a pressurized state in the first embodiment of the present invention, and FIG. FIG. 10 is a first enlarged view of main parts showing the fixing device when it is placed in a pressurized state in the first embodiment of the present invention. 11 is a longitudinal sectional view showing the fixing device in the released state in the first embodiment of the present invention; FIG. 12 is a second enlarged view of the main parts of the fixing device; FIG. FIG. 13 is a longitudinal cross-sectional view showing the fixing device in the released state in the first embodiment of the present invention; FIG. FIG. 14 is a second enlarged view of main parts showing the fixing device in the released state in the first embodiment of the present invention.

9 is an enlarged view of area Ar1 in FIG. 7 in a pressurized state, FIG. 10 is an enlarged view of area Ar2 in FIG. 7 in a pressurized state, and FIG. 13 is an enlarged view of area Ar1 in FIG. 12 in a released state. 14 is an enlarged view of area Ar2 in FIG. 12 in the released state.

In the figure, 18 is a fixing device, 21 is a belt unit, and 22 is a backup roller. The fixing device includes an endless fixing belt 51 that is movably disposed to face each other, and a heater unit 61 that is disposed within the fixing belt 51 and serves as a heating unit that heats the fixing belt 51.

The backup roller 22 is rotatably supported by the housing Hs around shafts sh1 at both ends, and is rotated by rotation from a fixing motor (not shown) serving as a fixing drive unit.

The fixing belt 51 is made to run as the backup roller 22 rotates, and includes a base material made of a buffer metal layer or a resin layer, an elastic layer made of silicone rubber formed surrounding the base material, and the elastic layer. It has a PFA tube etc. as a surface layer formed surrounding it. The PFA tube is formed from a resin consisting of a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene.

As shown in FIGS. 1 and 3, the heater unit 61 includes a frame Fr1 that is vertically movably supported by the housing Hs, is disposed within the frame Fr1, is made of a resistance heating element, and is connected to the fixing belt 51. a heater Ht1 as a heating member that heats the fixing belt 51; a heat diffusion member 55 disposed in contact with the inner circumferential surface of the fixing belt 51 between the heater Ht1 and the fixing belt 51; attached to the frame Fr1; A holder Fd2 that holds the heater Ht1 and the heat diffusion member 55 is disposed on the frame Fr1, urges the heater unit 61 downward with a predetermined urging force, and presses the heater unit 61 downward through the fixing belt 51 to the backup roller 22. springs sp11 and sp12 as first urging members that press against the holder Fd2; and a second urging member that connects the frame Fr1 and the heat diffusion member 55 and presses the heater Ht1 and the heat diffusion member 55 against the holder Fd2 with a predetermined urging force. It is equipped with a spring sp13 and the like.

Note that, as current is supplied to the heater Ht1 and the heater Ht1 generates heat, the holder Fd2, the heater Ht1, and the thermal diffusion member 55 expand with a coefficient of thermal expansion depending on their respective materials. At this time, if the holder Fd2, the heater Ht1, and the heat diffusion member 55 are connected by a fixing member such as a screw, the heater unit 61 will be deformed. Therefore, in this embodiment, the holder Fd2, the heater Ht1, and the heat diffusion member 55 are connected by the biasing force of the spring sp13 so that they can be thermally contracted independently of each other.

The spring sp13 is disposed at a predetermined location in the longitudinal direction of the heater unit 61, in this embodiment, at one end (the end in the negative direction of the y-axis) of the heater unit 61.

Further, a connector 57 is attached to a predetermined location in the longitudinal direction of the heater Ht1, in this embodiment, the other end (end in the positive direction of the y-axis) of the heater Ht1, and a current from a power supply device (not shown) is connected to the connector 57. It is supplied to the heater Ht1 via 57. The connector 57 includes first and second connector parts 65 and 66 that sandwich the heater Ht1, and a connector holder 68 that holds the first and second connector parts 65 and 66.

The holder Fd2 is formed of a resin such as a liquid crystal polymer, and has a recess 63 (FIG. 6) formed on the surface facing the heater Ht1, and a temperature sensor 64 as a temperature detection section is disposed in the recess 63.

When a current is supplied from the power supply device to the heater Ht1 and the heater Ht1 is turned on, the fixing belt 51 is heated, and when the temperature of the fixing belt 51 detected by the temperature sensor 64 reaches the set fixing temperature, the paper P is sent to the fixing device 18.

The heat diffusion member 55 diffuses the heat generated by the heater Ht1 and uniformly heats the fixing belt 51. Therefore, the heat diffusion member 55 is formed of a material with high thermal conductivity, for example, a metal material such as aluminum or stainless steel, and in this embodiment, aluminum.

In order to efficiently transfer the heat of the heater Ht1 to the heat diffusion member 55, heat transfer is promoted between the heater Ht1 and the heat diffusion member 55, in this embodiment, to the surface of the heat diffusion member 55. Grease gr (FIG. 6) is applied as a heat transfer promoter.

The springs sp11 and sp12 are disposed at predetermined positions of the frame Fr1, in this embodiment, in contact with both ends of the frame Fr1, and the spring sp13 is disposed at one end in the longitudinal direction of the heater unit 61 (y-axis negative The frame Fr1 and the heat diffusion member 55 are connected to each other at the end of the direction).

In order to move the belt unit 21 in the vertical direction within the housing Hs, a lifting mechanism (not shown) is provided on the frame Fr1. The elevating mechanism includes a cam rotatably disposed at the lower part of the frame Fr1, and an elevating motor as an elevating drive unit that rotates the cam, and when the elevating motor is driven and the cam is rotated, Depending on the shape of the cam surface, the frame Fr1 is pushed upward against the urging force of the springs sp11 and sp12, and the belt unit 21 is moved upward, or the frame Fr1 is pushed upward by the urging force of the springs sp11 and sp12. The belt unit 21 is pushed downward, and the belt unit 21 is moved downward.

Note that, instead of the cam, the elevating mechanism may be formed by a nut disposed on the frame Fr1 and a screw connected to the output shaft of the elevating motor and screwed into the nut. In that case, the belt unit 21 is moved in the vertical direction by rotating the lifting motor in the forward and reverse directions.

In the pressurized state of the fixing device 18, the frame Fr1 is pushed downward by the biasing forces of springs sp11 and sp12 disposed at both ends of the frame Fr1, the heater unit 61 is lowered, and the fixing belt 51 is The heat diffusion member 55 is pressed against the backup roller 22, and thereby, as shown in FIGS. 9 and 10, the heat diffusion member 55 is brought into close contact with the heater Ht1.

Then, current is supplied to the heater Ht1 via the connector 57, and the toner image on the paper P is heated and pressed onto the paper P in the nip formed between the fixing belt 51 and the backup roller 22. be established.

On the other hand, in the released state of the fixing device 18, the frame Fr1 is pushed upward by the elevating mechanism against the urging force of the springs sp11 and sp12, and the heater unit 61 is raised and separated from the backup roller 22. As a result, the fixing belt 51 has a rounded shape at the nip portion.

At this time, the heater Ht1 is held between the first and second connector parts 65 and 66 at the other end in the longitudinal direction (the end in the positive direction of the y-axis) of the heater unit 61, and at one end in the longitudinal direction of the heater unit 61. (the end in the negative direction of the y-axis), the thermal diffusion member 55 is pressed against the holder Fd2 by the urging force of the spring sp13.

Therefore, the heat diffusion member 55 is held by the adhesive force of the grease gr at the other end in the longitudinal direction of the heater unit 61, and is urged upward by the urging force of the spring sp13 at one end in the longitudinal direction of the heater unit 61. The entire area is brought into close contact with the heater Ht1. That is, as shown in FIGS. 13 and 14, the heat diffusion member 55 is brought into close contact with the heater Ht1.

As described above, in the present embodiment, when the fixing device 18 is in the released state, the heat diffusion member 55 is brought into close contact with the heater Ht1 by the biasing force of the spring sp13. It is possible to prevent unevenness from occurring in the applied grease gr.

Therefore, when the fixing device 18 is placed under pressure and current is supplied to the heater Ht1, the fixing belt 51 can be uniformly heated, so that the toner image can be well fixed on the paper P. , image quality can be improved.

Next, a second embodiment of the present invention will be described. Components having the same structure as those in the first embodiment are given the same reference numerals, and the effects of the first embodiment are referred to for the effects of the invention due to having the same structure.

FIG. 15 is a conceptual diagram showing the pressurized state of the fixing device in the second embodiment of the present invention, and FIG. 16 is a conceptual diagram showing the released state of the fixing device in the second embodiment of the present invention.

In the figure, 61 is a heater unit as a heating unit, and the heater unit 61 includes a frame Fr1 that is movably supported in the vertical direction by a housing Hs (FIG. 4), and is disposed within the frame Fr1 and generates resistance heat. a heater Ht1 as a heating member that heats the fixing belt 51; a heat diffusion member 56 disposed in contact with the inner peripheral surface of the fixing belt 51 between the heater Ht1 and the fixing belt 51; A holder Fd3 that holds the heater Ht1 and the heat diffusion member 56 movably in the vertical direction with respect to the frame Fr1, which is disposed on the frame Fr1 and biases the heater unit 61 downward with a predetermined biasing force. The springs sp11 and sp12 as first biasing members that press against the backup roller 22 as the second fixing member via the fixing belt 51, the frame Fr1 and the heat diffusion member 56 are connected, and the heat diffusion member 56 is connected by a predetermined biasing force. A spring sp13 and the like are provided as a second biasing member that presses the heater Ht1 and the heat diffusion member 56 against the holder Fd3.

The spring sp13 is disposed at a predetermined location in the longitudinal direction of the heater unit 61, in this embodiment, at one end (the end in the negative direction of the y-axis), connecting the frame Fr1 and the heat diffusion member 56. Ru.

Further, a locking portion En3 is formed at a predetermined location in the longitudinal direction of the heat diffusion member 56 and the holder Fd3, in this embodiment, the other end (the end in the positive direction of the y-axis), and the heat diffusion member 56 is attached to the holder Fd3. Retained by Fd3. For this purpose, a hook 71 as a locking member is formed to protrude from the heat diffusion member 56, a notch 72 as a locked member is formed in the holder Fd3, and the hook 71 and the notch 72 are locked. I am made to do so.

In this case, the heat diffusion member 56 is held by the hook 71 and the notch 72 at the other end of the heater unit 61, and is held by the adhesive force of the grease gr (FIG. 6) as a heat transfer promoter. At one end of the heater unit 61, the heater unit 61 is urged upward by the urging force of the spring sp13, and the entire area is brought into close contact with the heater Ht1, so that the fixing device 18 is placed in a pressurized state and current is supplied to the heater Ht1. At times, the fixing belt 51 can be heated uniformly.

Next, a third embodiment of the present invention will be described. Components having the same structure as those in the first embodiment are given the same reference numerals, and the effects of the first embodiment are referred to for the effects of the invention due to having the same structure.

FIG. 17 is a conceptual diagram showing the released state of the fixing device in the third embodiment of the present invention.

In the figure, 61 is a heater unit as a heating unit, and the heater unit 61 includes a frame Fr1 that is movably supported in the vertical direction by a housing Hs (FIG. 4), and is disposed within the frame Fr1 and generates resistance heat. a heater Ht1 as a heating member that heats the fixing belt 51; a heat diffusion member 55 disposed in contact with the inner peripheral surface of the fixing belt 51 between the heater Ht1 and the fixing belt 51; A holder Fd2 that holds the heater Ht1 and the heat diffusion member 55 is disposed on the frame Fr1, and biases the heater unit 61 downward with a predetermined biasing force. Springs sp11 and sp12 as first biasing members that press against the backup roller 22 as a fixing member connect the frame Fr1 and the heat diffusion member 55, and apply a predetermined biasing force to move the heater Ht1 and the heat diffusion member 55 to the holder Fd2. A spring sp14 and the like are provided as a second urging member for pressing.

The spring sp14 is disposed at a predetermined location of the heater unit 61, in this embodiment, at both ends of the heater unit 61, connecting the frame Fr1 and the heat diffusion member 55.

In this case, the heat diffusion member 55 is held by the adhesive force of grease gr (FIG. 6) as a heat transfer promoter, and is urged upward by the urging force of the spring sp14 at both ends of the heater unit 61. Since the entire area is brought into close contact with the heater Ht1, the fixing belt 51 can be uniformly heated when the fixing device 18 as a fixing device is placed in a pressurized state and current is supplied to the heater Ht1.

Although the printer 10 has been described in each of the embodiments, the present invention can be applied to image forming apparatuses such as copying machines, facsimile machines, and multifunction devices.

Note that the present invention is not limited to the embodiments described above, and various modifications can be made based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

18 Fixing device 21 Belt unit 22 Backup roller 51 Fixing belts 55, 56 Heat diffusion member 61 Heater unit gr Grease Ht1 Heater P Paper sp11 to sp14 Spring

Claims (10)

It has first and second fixing members, and in a pressurized state, the medium is held between the first and second fixing members by the urging force of the first urging member, and the developer image on the medium is fixed. a fixing device in which the first and second fixing members are separated from each other in a released state;
(a) The first fixing member includes an endless fixing belt that is movably disposed facing the second fixing member, and a heating unit that is disposed within the fixing belt and heats the fixing belt. Equipped with
(b) The heating unit includes a heating member, a heat diffusion member disposed between the heating member and the fixing belt and configured to diffuse heat generated by the heating member, and a space between the heating member and the heat diffusion member. It is characterized by having a heat transfer accelerator disposed in and promoting heat transfer, and a second biasing member that biases the heat diffusion member toward the heating member by a biasing force in the released state. Fusing device. (a) the heating unit includes a frame;
(b) The fixing device according to claim 1, wherein the frame and the heat diffusion member are connected by the second biasing member. (a) the heating unit includes a holder attached to the frame;
(b) The fixing device according to claim 2, wherein the heating member and the heat diffusion member are pressed against the holder by the urging force of the second urging member. The fixing device according to claim 3, wherein the second biasing member is disposed at one end in the longitudinal direction of the heating unit. 5. The fixing device according to claim 4, wherein the heat diffusion member is held at the other end in the longitudinal direction of the heating unit by the adhesive force of a heat transfer promoter. The fixing device according to claim 4, wherein the heat diffusion member and the holder are engaged with each other at the other end in the longitudinal direction of the heating unit. The fixing device according to claim 3, wherein the second biasing member is disposed at both ends of the heating unit in the longitudinal direction. The fixing device according to claim 2, wherein the first biasing member biases the heating unit downward and presses it against the second fixing member. The fixing device according to any one of claims 4 to 7, wherein a connector for supplying current to the heating member is disposed at the other end in the longitudinal direction of the heating unit. An image forming apparatus comprising the fixing device according to claim 1.

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