JP2008107390A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device which suppresses image defects such as offset when a large-size paper is passed after a small-size paper is passed. <P>SOLUTION: The fixing device has: a heating roller 1 and a pressure belt 2 which are rotated in contact with each other; a heating heater 11 which heats the heating roller 1; and an elastic pressing portion 3 and a non-elastic pressing portion 4 which are arranged inside the pressure belt 2 and press the pressure belt 2 toward the heating roller 1. The thermal conductivity of the end portion of the non-elastic pressing portion 4 in the axial direction of the pressure belt 2 is larger than that of the central portion of the non-elastic pressing portion 4 in the axial direction of the pressure belt 2. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a fixing device used for, for example, a copying machine, a laser printer, a facsimile, and the like, and an image forming apparatus using the fixing device.

Conventionally, the fixing device has a heating roller that is heated by a heating source, a pressure belt that contacts the peripheral surface of the heating roller, and a pressure contact member that presses the pressure belt against the heating roller from the inside. The recording paper is sandwiched between the heating roller and the pressure belt, and the toner image is heated and melted and fixed on the recording paper (see Japanese Patent Laid-Open No. 2002-372887: Patent Document 1).
Japanese Patent Laid-Open No. 2002-372887

  However, in the conventional fixing device, when a small-sized recording material is continuously passed between the heating roller and the pressure belt, the temperature of the end portion that is the outer area of the heating roller passes through. After that, when a large-size recording material is passed, there is a problem that image trouble such as offset occurs.

  In particular, when the heat capacity of the heating roller is reduced in order to reduce the electric power for increasing the temperature of the heating roller and shorten the time, the heating roller having a small heat capacity does not transfer heat in the axial direction. There is a problem in that it is more difficult to occur and an image defect occurs.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fixing device that suppresses image troubles such as offset at the time of passing a large size after passing a small size.

In order to solve the above problems, the fixing device of the present invention is:
A heating rotator and a pressure rotator that rotate together in contact with each other;
A heating unit for heating the heating rotator;
An elastic pressing portion that is disposed inside the pressure rotator and elastically deforms and presses the pressure rotator toward the heating rotator;
The heating unit is disposed inside the pressurizing rotator, and further on the downstream side in the rotation direction of the pressurizing rotator on the contact surface between the heating rotator and the pressurizing rotator than the elastic pressing portion. An inelastic pressing portion that presses the pressure rotating body toward the rotating body,
The heat dissipation performance of the end portion of the inelastic pressing portion in the axial direction of the pressurizing rotating body is greater than the heat dissipation performance of the central portion of the inelastic pressing portion in the axial direction of the pressurizing rotating body.

  Here, the said edge part of the said inelastic press part and the said center part of the said inelastic press part each include the press surface which presses the said pressurization rotary body of the said inelastic press part. “The heat dissipation of the inelastic pressing portion” means that the heat of the heating rotator is radiated.

  According to the fixing device of the present invention, the heating rotator and the pressure rotator that rotate in contact with each other, the heating unit that heats the heating rotator, and the pressure rotator facing the heating rotator. An inelastic pressing portion that presses the heat rotating body when the inelastic pressing portion presses the heating rotating body via the pressure rotating body. It is transmitted to.

  And since the heat dissipation of the said edge part of the said inelastic press part is larger than the heat dissipation of the said center part of the said inelastic press part, it is small between the said heating rotary body and the said pressurization rotary body. When a recording material of a size is passed, the heat at the axial end portion of the heating rotator is radiated from the end portion of the inelastic pressing portion by the end portion having high heat dissipation of the inelastic pressing portion. Thus, the temperature rise at the end of the heating rotator can be prevented.

  On the other hand, the heat of the central portion in the axial direction of the heating rotator is difficult to move to the central portion of the inelastic pressing portion by the central portion having a small heat dissipation property of the inelastic pressing portion. It becomes easy to move to the said edge part, and the temperature of the said heating rotary body is equalized over an axial direction.

  Therefore, it is possible to suppress the occurrence of offset, paper wrinkles, and the like when passing a large size after passing a small size.

  In the fixing device according to an embodiment, the end of the inelastic pressing portion is configured such that the heat dissipation of the end of the inelastic pressing portion is greater than the heat dissipation of the central portion of the inelastic pressing portion. The material of the part and the central part of the inelastic pressing part are different.

  According to the fixing device of this embodiment, the end of the inelastic pressing portion is configured such that the heat dissipation of the end of the inelastic pressing portion is greater than the heat dissipation of the central portion of the inelastic pressing portion. Since the material of the central portion of the non-elastic pressing portion is different from that of the central portion of the non-elastic pressing portion, the heat dissipation performance of the end portion of the non-elastic pressing portion is reliably ensured. Can be bigger.

  In the fixing device according to the embodiment, the thermal conductivity of the end portion of the inelastic pressing portion is larger than the thermal conductivity of the central portion of the inelastic pressing portion.

  According to the fixing device of this embodiment, since the thermal conductivity of the end portion of the inelastic pressing portion is larger than the thermal conductivity of the central portion of the inelastic pressing portion, it is ensured that the inelastic pressing portion is The heat dissipation of the end of the part can be made larger than the heat dissipation of the central part of the inelastic pressing part.

  In the fixing device according to an embodiment, the area of the pressing surface that presses the pressure rotator at the end of the inelastic pressing portion is equal to the pressure rotator at the center of the inelastic pressing portion. It is larger than the area of the pressing surface to be pressed.

  According to the fixing device of this embodiment, the area of the pressing surface at the end of the inelastic pressing portion is larger than the area of the pressing surface at the central portion of the inelastic pressing portion. The heat dissipation of the end of the inelastic pressing portion can be made larger than the heat dissipation of the central portion of the inelastic pressing portion.

  In one embodiment, the fixing device includes a support portion that supports the elastic pressing portion and the inelastic pressing portion.

  According to the fixing device of this embodiment, since the elastic pressing portion and the inelastic pressing portion are supported, the elastic pressing portion and the inelastic pressing portion are simultaneously added to the additional pressure by the supporting portion. The heating rotary body can be pressed via the pressure rotary body.

  In the fixing device according to the embodiment, the inelastic pressing portion integrally forms a support portion that supports the elastic pressing portion.

  According to the fixing device of this embodiment, since the inelastic pressing portion integrally forms a support portion that supports the elastic pressing portion, the surface area of the inelastic pressing portion can be increased, and the non-elastic pressing portion can be increased. The heat dissipation of the elastic pressing part can be further improved.

In the fixing device according to an embodiment, a length of the heating unit in the heating rotator axial direction is shorter than a length of the inelastic pressing unit in the pressure rotator axial direction.
When viewed from the direction orthogonal to the heating rotator axis and the pressurizing rotator axis, the heating part is inside the inelastic pressing part.

  According to the fixing device of this embodiment, the length of the heating unit in the heating rotator axis direction is shorter than the length of the inelastic pressing unit in the pressure rotator axis direction, and the heating rotator shaft and When viewed from the direction orthogonal to the pressure rotating body axis, the heating part is inside the inelastic pressing part, so that the end of the inelastic pressing part extends to the outside of the end of the heating part. It can arrange | position and the said edge part of the said inelastic press part becomes difficult to be heated by the said heating part, and can further improve the heat dissipation of the said edge part of the said inelastic press part.

In the fixing device of one embodiment,
The heating part is
A heating part for passing small size paper that heats the central part other than the end part in the axial direction of the heating rotator,
A heating section for passing large-size sheets that heats the axial end and center of the heating rotator.

  According to the fixing device of this embodiment, the heating unit includes a heating unit for small-size sheet passing that heats the central portion other than the end in the axial direction of the heating rotator, and an axial direction of the heating rotator. A heating unit for passing large-size paper that heats the end and the center, so that when the large-size recording material is passed between the heating rotating body and the pressing rotating body, On the other hand, when a small-size recording material is passed between the heating rotator and the pressure rotator, using the heating unit for small-size paper passing, It is possible to more reliably prevent the temperature rise at the end of the heating rotator when a small size is passed.

  Further, in the fixing device according to an embodiment, each of the end portion and the center portion in the axial direction of the heating rotating body is heated based on the thermal conductivity of each of the end portion and the center portion of the inelastic pressing portion. A control unit for setting the output of the heating unit when performing.

  According to the fixing device of this embodiment, each of the end portion and the central portion of the heating rotating body is heated based on the thermal conductivity of each of the end portion and the central portion of the inelastic pressing portion. Since it has a control unit that sets the output of the heating unit when, compared to the conventional case where the thermal conductivity of each of the end portion and the central portion of the inelastic pressing portion is uniform, It is possible to make the output of the heating part uniform when heating each of the end part and the central part of the heating rotator, and it is easy to set the output of the heating part.

  Further, in the fixing device according to an embodiment, each of the end portion and the central portion in the axial direction of the heating rotating body is based on the thermal conductivity of each of the end portion and the central portion of the inelastic pressing portion. It has a control part which sets up contact pressure to a pressurization rotating body.

  According to the fixing device of this embodiment, based on the respective thermal conductivities of the end portion and the center portion of the inelastic pressing portion, each of the end portion and the center portion of the heating rotator is subjected to the addition. Since it has a control part which sets contact pressure to a pressure rotating body, compared with the case where each thermal conductivity of the above-mentioned end part of the above-mentioned inelastic press part and the above-mentioned central part is uniform like the past, The contact pressure at the end and the center of the heating rotator can be made uniform, and the contact pressure of the heating rotator can be easily set.

  An image forming apparatus according to the present invention includes the fixing device.

  According to the image forming apparatus of the present invention, since the fixing device is provided, a high quality image forming apparatus can be realized.

  According to the fixing device of the present invention, the heat dissipation property of the end portion of the inelastic pressing portion is greater than the heat dissipation property of the central portion of the inelastic pressing portion. It is possible to suppress image trouble such as offset at the time of paper.

  Also, according to the image forming apparatus of the present invention, since the fixing device is provided, a high quality image forming apparatus can be realized.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

(First embodiment)
FIG. 1 is a simplified configuration diagram showing a first embodiment of a fixing device according to the present invention. This fixing device heats the heating roller 1 (as a heating rotator) and the pressure belt 2 (as a pressure rotator) rotating together with the outer peripheral surfaces in contact with each other, and the heating roller 1 (heating unit). And a heating heater 11 and an elastic pressing portion 3 and an inelastic pressing portion 4 that are disposed inside the pressure belt 2 and press the pressure belt 2 toward the heating roller 1.

  The elastic pressing portion 3 and the inelastic pressing portion 4 are formed along the axial direction of the pressure belt 2 to have substantially the same length as the width dimension of the heating roller 1 and the pressure belt 2. .

  The elastic pressing portion 3 elastically deforms and presses the pressure belt 2 toward the heating roller 1. The inelastic pressing portion 4 is directed toward the heating roller 1 on the downstream side in the rotation direction of the pressure belt 2 on the contact surface between the heating roller 1 and the pressure belt 2 with respect to the elastic pressing portion 3. Then, the pressure belt 2 is pressed.

  The heating roller 1 is rotated by a driving unit such as a motor (not shown), and the pressure belt 2 rotates following the rotation of the heating roller 1 by friction with the heating roller 1.

  The heating roller 1 and the pressure belt 2 are in contact with each other and fix the toner t of the recording material P while conveying the recording material P. More specifically, a nip portion is formed by contact between the heating roller 1 and the pressure belt 2, and the recording material P is melted and fixed by the nip portion while the toner t of the recording material P is melted and fixed. Transport.

  The toner t is satisfactorily fixed on the recording material P by the pressing due to the elastic deformation of the elastic pressing portion 3. By the pressing of the inelastic pressing portion 4, the heating roller 1 is distorted, the adhesive force between the recording material P and the heating roller 1 is reduced, and the recording material P can be easily peeled off.

  The recording material P is, for example, a sheet such as paper or an OHP sheet. A toner t is attached to one surface of the recording material P, and the toner t is made of a material having heat melting properties such as a resin, a magnetic material, or a colorant.

  The heating roller 1 is in contact with one surface (image surface) of the recording material P. The heating roller 1 is a hollow roller, and has a core layer, an elastic layer, and a surface layer in order from the inside to the outside. The outer diameter of the heating roller 1 is, for example, 26 mm. The core layer is made of aluminum having a thickness of 2 mm, for example. The elastic layer is made of, for example, silicon rubber having a thickness of 200 μm. The surface layer is made of a PFA tube having a thickness of 20 μm, for example.

  The surface temperature of the heating roller 1 is detected by the thermistor 10, and the output of the heater 11 is adjusted based on the detected temperature of the thermistor 10. For example, the 700 W heater 11 is adjusted so that the temperature detected by the thermistor 10 is 190 ° C.

  The pressure belt 2 is an endless belt, and the outer diameter of the pressure belt 2 is, for example, 30 mm and is made of polyimide having a thickness of 70 μm.

  A belt guide 7 for guiding the pressure belt 2 from the inside is provided inside the pressure belt 2. Inside the pressure belt 2, a support portion 5 that supports the elastic pressing portion 3 and the inelastic pressing portion 4 is provided. The support portion 5 and the belt guide 7 are connected by a connecting portion 6, and the pressure belt 2 is moved from the inside by the elastic pressing portion 3 and the inelastic pressing portion 4 and the belt guide 7. , Support while applying tension. The support portion 5 can simultaneously press the elastic pressing portion 3 and the inelastic pressing portion 4 against the heating roller 1 via the pressure belt 2.

  The pressure belt 2 is pressed against the heating roller 1 by a load of 100 to 530 N by the elastic pressing portion 3 and the inelastic pressing portion 4. In this case, the width dimension of the nip portion (the dimension in the rotation direction of the pressure belt 2) is about 9 mm. The length of the nip portion (the dimension of the pressure belt 2 in the rotation axis direction) is about 240 mm.

  Note that the pressure of the nip portion can be changed by a nip pressure adjusting portion (not shown) that relatively approaches or separates the heating roller 1 and the pressure belt 2.

  The elastic pressing portion 3 is made of, for example, silicon rubber having a rubber hardness of 10 ° to 20 °. The elastic pressing portion 3 is curved in a shape along the outer peripheral surface of the heating roller 1.

  As shown in FIG. 2, the heat dissipation of the end portion 41 of the inelastic pressing portion 4 in the axial direction of the pressure belt 2 is the heat dissipation of the central portion 40 of the inelastic pressing portion 4 in the axial direction of the pressure belt 2. Greater than sex. Here, the end portion 41 and the central portion 40 of the inelastic pressing portion 4 each include a pressing surface 4 a that presses the pressure belt 2 of the inelastic pressing portion 4. The heat radiating property of the inelastic pressing portion 4 is to radiate the heat of the heating roller 1.

  That is, the materials of the end 41 and the central portion 40 of the inelastic pressing portion 4 are different, and the thermal conductivity of the end 41 of the inelastic pressing portion 4 is the inelastic pressing portion 4. Greater than the thermal conductivity of the central portion 40.

  More specifically, the end portion 41 is made of aluminum as a high heat conductive material, and the central portion 40 is made of iron as a low heat conductive material. The axial length of the central portion 40 is 140 mm, and the axial lengths of the both end portions 41 and 41 are each 100 mm. That is, the axial range of the central portion 40 is an area through which a small size recording material P is passed.

  The central portion 40 may be a low thermal conductive resin of 10 W / (m · K) or less, and examples thereof include a synthetic resin having heat resistance such as LCP, PET, PPS. The end portion 41 may be a high thermal conductive resin of 80 W / (m · K) or more, for example, a material having a graphite type crystal structure or a diamond type crystal structure.

  Further, the central portion 40 and the end portion 41 may be constituted by a combination of a metal such as iron, aluminum, copper, and magnesium, or an alloy containing these and the resin, and the thermal conductivity of the end portion 41. May be larger than the thermal conductivity of the central portion 40.

  According to the fixing device having the above configuration, when the inelastic pressing portion 4 presses the heating roller 1 via the pressure belt 2, the heat of the heating roller 1 is transmitted to the inelastic pressing portion 4. .

  And since the heat dissipation of the said edge part 41 of the said inelastic press part 4 is larger than the heat dissipation of the said center part 40 of the said inelastic press part 4, between the said heating roller 1 and the said pressure belt 2 When the recording material P having a small size is passed there between, the heat at the end in the axial direction of the heating roller 1 is applied by the inelastic pressing portion 41 by the end 41 having a large heat dissipation property of the inelastic pressing portion 4. Heat is radiated from the end portion 41 of the portion 4, and temperature rise at the end portion of the heating roller 1 can be prevented.

  On the other hand, the heat at the central portion in the axial direction of the heating roller 1 is difficult to move to the central portion 40 of the inelastic pressing portion 4 by the central portion 40 having a small heat dissipation property of the inelastic pressing portion 4. It becomes easy to move to the said edge part of the heating roller 1, and the temperature of the said heating roller 1 is equalized over an axial direction.

  Therefore, it is possible to suppress the occurrence of offset, paper wrinkles, and the like when passing a large size after passing a small size.

  The material of the end 41 of the inelastic pressing part 4 and the center part 40 of the inelastic pressing part 4 are different, and the thermal conductivity of the end 41 of the inelastic pressing part 4 is Since it is larger than the thermal conductivity of the central portion 40 of the non-elastic pressing portion 4, the heat dissipation of the end portion 41 of the non-elastic pressing portion 4 is surely ensured. It can be larger than heat dissipation.

(Second Embodiment)
In the second embodiment of the fixing device of the present invention, instead of changing the thermal conductivity of the central portion 40 and the end portion 41 of the first embodiment shown in FIG. The area of the pressing surface 4a that presses the pressure belt 2 at the end portion 41 is made larger than the area of the pressing surface 4a that presses the pressure belt 2 at the central portion 40 of the inelastic pressing portion 4. Yes.

  Therefore, the heat dissipation of the end portion 41 of the inelastic pressing portion 4 can be surely made larger than the heat dissipation of the central portion 40 of the inelastic pressing portion 4.

(Third embodiment)
FIG. 3 shows a third embodiment of the fixing device of the present invention. The difference from the first embodiment (FIG. 1) will be described. In the third embodiment, the inelastic pressing portion 14 is integrally formed with a support portion 42 that supports the elastic pressing portion 3. is doing. The inelastic pressing part 14 is supported by the support part 5 connected to the connection part 6.

  Therefore, the surface area of the inelastic pressing portion 14 can be increased, and the heat dissipation of the inelastic pressing portion 14 can be further improved.

(Fourth embodiment)
FIG. 4 shows a fourth embodiment of the fixing device of the present invention. The difference from the first embodiment (FIG. 1) will be described. In the fourth embodiment, the inelastic pressing portion 24 integrally forms a support portion 43 that supports the elastic pressing portion 3. is doing. The support portion 43 of the inelastic pressing portion 24 is connected to the connecting portion 6.

  Therefore, the surface area of the inelastic pressing portion 24 can be increased, and the heat dissipation of the inelastic pressing portion 24 can be further improved.

(Fifth embodiment)
FIG. 5 shows a fifth embodiment of the fixing device of the present invention. The difference from the first embodiment (FIG. 1) will be described. In the fifth embodiment, the length of the heater 11 in the axial direction of the heating roller 11 is the same as that of the inelastic pressing portion 4. The heater 11 is inside the inelastic pressing portion 4 when viewed from a direction that is shorter than the length of the pressure belt 2 axis and is orthogonal to the heating roller 1 axis and the pressure belt 2 axis.

  Therefore, the end portion 41 of the inelastic pressing portion 4 can be disposed to the outside of the end portion of the heater 11, and the end portion 41 of the inelastic pressing portion 4 is heated by the heater 11. It becomes difficult, and the heat dissipation of the end portion 41 of the inelastic pressing portion 4 can be further improved.

(Sixth embodiment)
FIG. 6 shows a sixth embodiment of the fixing device of the present invention. The difference from the first embodiment (FIG. 1) will be described. In the sixth embodiment, the heater 11 is a small heater that heats the central portion other than the end portion in the axial direction of the heating roller 1. A heater 11a for passing size paper and a heater 11b for passing large size paper for heating the axial end and center of the heating roller 1 are included.

  Therefore, when the large size recording material P is passed between the heating roller 1 and the pressure belt 2, the heating heater 11b for passing the large size paper is used, while the heating roller 1 and the heating belt 11 are added. When the small size recording material P is passed between the pressure belt 2 and the heater 11a for passing the small size, the temperature of the end of the heating roller 1 when passing the small size is used. The rise can be prevented more reliably.

(Seventh embodiment)
FIG. 7 shows a seventh embodiment of the fixing device of the present invention. The difference from the first embodiment (FIG. 1) will be described. In the seventh embodiment, based on the respective thermal conductivities of the end portion 41 and the central portion 40 of the inelastic pressing portion 4. And a control unit 8 for setting the output of the heater 11 when heating the axial end and center of the heating roller 1.

  Therefore, as compared with the conventional case where the thermal conductivity of each of the end portion 41 and the central portion 40 of the inelastic pressing portion 4 is uniform, the end portion and the central portion of the heating roller 1 are compared. It is possible to make the output of the heater 11 uniform when heating each part, and to easily set the output of the heater 11.

(Eighth embodiment)
FIG. 8 shows an eighth embodiment of the fixing device of the present invention. The difference from the first embodiment (FIG. 1) will be described. In the eighth embodiment, based on the thermal conductivity of each of the end portion 41 and the central portion 40 of the inelastic pressing portion 4. The control unit 9 sets the contact pressure of the heating roller 1 in the axial direction with respect to the pressure belt 2 at the end and the center.

  Therefore, as compared with the conventional case where the thermal conductivity of each of the end portion 41 and the central portion 40 of the inelastic pressing portion 4 is uniform, the end portion and the central portion of the heating roller 1 are compared. The contact pressure of the part can be made uniform, and the contact pressure of the heating roller 1 can be easily set.

(Ninth embodiment)
FIG. 9 shows a ninth embodiment of the fixing device of the present invention. The difference from the first embodiment (FIG. 1) will be described. In the ninth embodiment, an electromagnetic induction heating unit 71 is used instead of the heater 11 as a heating unit for heating the heating roller 1. Is used.

  The electromagnetic induction heating unit 71 has a core 71 a and a coil 71 b and is disposed inside the heating roller 1. The electromagnetic induction heating unit 71 generates magnetic flux from the inside of the heating roller 1 and heats the heating roller 1 by electromagnetic induction.

(Tenth embodiment)
FIG. 10 shows a tenth embodiment of the fixing device of the present invention. The difference from the first embodiment (FIG. 1) will be described. In the tenth embodiment, a heating belt 75 is used instead of the heating roller 1 as a heating rotator.

  The heating belt 75 is wound around a first roller 76 and a second roller 77. The heater 11 is disposed inside the first roller 76. The second roller 77 faces the pressure belt 2.

  By rotating at least one of the first roller 76 and the second roller 77, the heating belt 75 is driven to rotate and is heated from the heater 11 via the first roller 76. Receive. Then, fixing is performed by a nip portion formed by contact between the heating belt 75 and the pressure belt 2.

(Eleventh embodiment)
FIG. 11 is a simplified configuration diagram showing an embodiment of the image forming apparatus according to the present invention. The image forming apparatus includes an image forming apparatus 80 that forms an image by attaching unfixed toner t to the recording material P, and the first embodiment in which the toner t is melted and fixed to the recording material P. The fixing device 81 is provided. This image forming apparatus is an electrophotographic 4-color printer.

  The image forming device 80 includes an intermediate transfer belt 61, four image forming units 51 that are arranged along the intermediate transfer belt 61 and that form toner images, and toner images formed by the image forming units 51. Are transferred to the intermediate transfer belt 61, and a secondary transfer portion 63 is formed to transfer the image transferred to the intermediate transfer belt 61 onto the recording material P.

  The image forming unit 51 that forms a black (BK) toner image, the image forming unit 51 that forms a yellow (Y) toner image, the image forming unit 51 that forms a magenta (M) toner image, and The image forming units 51 for forming a cyan (C) toner image are arranged in order from the upstream side to the downstream side of the intermediate transfer belt 61.

  Each of the image forming units 51 includes a photosensitive drum 52, a charging unit 53 for uniformly charging the photosensitive drum 52, and an exposure unit 59 for performing image exposure on the charged photosensitive drum 52. And a developing section 54 for developing the electrostatic latent image formed by exposure with toner of each color.

  The image forming apparatus includes a control device 68 that controls the entire image forming apparatus, and an exposure control device 69 to which a signal corresponding to the image is sent from the control device 68. The exposure control device 69 drives each of the exposure units 59 according to each color.

  Next, the operation of this image forming apparatus will be described.

  The toner image developed on the photosensitive drum 52 of the image forming unit 51 is primarily transferred onto the intermediate transfer belt 61 by the primary transfer unit 62 at a contact position with the intermediate transfer belt 61.

  Each time the toner image transferred onto the intermediate transfer belt 61 passes through each image forming unit 51, each color is superimposed thereon, and finally, a full-color toner image is transferred onto the intermediate transfer belt 61. Formed.

  Thereafter, the full-color toner image on the intermediate transfer belt 61 is secondarily transferred onto the recording material P by the secondary transfer unit 63 downstream of the intermediate transfer belt 61.

  The recording material P passes through the fixing device 81 on the downstream side of the conveyance path of the recording material P, whereby the toner image is fixed and discharged onto the discharge tray 66.

  The recording material P is stored in the lowermost cassette 67 and is conveyed one by one from the cassette 67 to the secondary transfer unit 63.

  The toner remaining on the photosensitive drum 52 after the primary transfer is removed by the cleaning unit 55 disposed downstream and collected from below the cleaning unit 55.

  The toner remaining on the intermediate transfer belt 61 after the secondary transfer is removed from the intermediate transfer belt 61 by the cleaning blade 65, conveyed by a conveyance screw (not shown), and collected in a waste toner container (not shown). The

  According to the image forming apparatus having the above configuration, since the fixing device 81 is provided, good fixed image performance can be obtained. The fixing device described in any of the second to tenth embodiments may be used as the fixing device of the image forming apparatus.

  In addition, this invention is not limited to the above-mentioned embodiment. For example, the pressure rotating body may be a roller other than the pressure belt 2. Further, the heater 11 may be disposed outside the heating roller 1.

  Further, the non-elastic member 4 has a thermal conductivity of the non-elastic member 4 from the end portion 41 to the central portion in order to eliminate a difference in fixing property between large-size paper passage and small-size paper passage. You may make it change to 40 gradually.

  Moreover, you may make it change the thermal conductivity of the said center part 40 and the said edge part 41 by providing a fin in the said inelastic member 4. FIG.

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

1 is a simplified configuration diagram illustrating a first embodiment of a fixing device according to the present invention. It is a simplified top view which shows the press surface of an inelastic press part. It is a simplified block diagram which shows 3rd Embodiment of the fixing device of this invention. It is a simplified block diagram which shows 4th Embodiment of the fixing device of this invention. It is a simplified block diagram which shows 5th Embodiment of the fixing device of this invention. It is a simplified block diagram which shows 6th Embodiment of the fixing device of this invention. FIG. 10 is a simplified configuration diagram illustrating a seventh embodiment of the fixing device of the present invention. It is a simple block diagram which shows 8th Embodiment of the fixing device of this invention. It is a simplified block diagram which shows 9th Embodiment of the fixing device of this invention. It is a simplified block diagram which shows 10th Embodiment of the fixing device of this invention. 1 is a simplified configuration diagram showing an image forming apparatus of the present invention.

Explanation of symbols

1 Heating roller (heated rotating body)
10 Thermistor 11 Heater (heating unit)
11a Heater for passing small size paper (heating part for passing small size paper)
11b Heater for passing large size paper (Heating part for passing large size paper)
2 Pressure belt (Pressurizing rotator)
DESCRIPTION OF SYMBOLS 3 Elastic press part 4,14,24 Inelastic press part 4a Press surface 40 Center part 41 End part 42,43 Support part 5 Support part 6 Connection part 7 Belt guide 8,9 Control part 71 Electromagnetic induction heating unit (heating part)
71a Core 71b Coil 75 Heating belt (Heating rotating body)
76 First roller 77 Second roller 80 Image forming device 81 Fixing device P Recording material t Toner

Claims (11)

A heating rotator and a pressure rotator that rotate together in contact with each other;
A heating unit for heating the heating rotator;
An elastic pressing portion that is disposed inside the pressure rotator and elastically deforms and presses the pressure rotator toward the heating rotator;
The heating unit is disposed inside the pressurizing rotator, and further on the downstream side in the rotation direction of the pressurizing rotator on the contact surface between the heating rotator and the pressurizing rotator than the elastic pressing portion. An inelastic pressing portion that presses the pressure rotating body toward the rotating body,
The heat dissipation of the end portion of the inelastic pressing portion in the axial direction of the pressing rotator is greater than the heat dissipation performance of the central portion of the inelastic pressing portion in the axial direction of the pressing rotator. apparatus. The fixing device according to claim 1,
The end portion of the inelastic pressing portion and the center of the inelastic pressing portion so that the heat dissipation performance of the end portion of the inelastic pressing portion is greater than the heat dissipation performance of the center portion of the inelastic pressing portion. The fixing device is characterized in that the material of the part is different. The fixing device according to claim 1,
The fixing device according to claim 1, wherein a thermal conductivity of the end portion of the inelastic pressing portion is larger than a thermal conductivity of the central portion of the inelastic pressing portion. The fixing device according to claim 1,
The area of the pressing surface that presses the pressing rotator at the end of the inelastic pressing portion is larger than the area of the pressing surface that presses the pressing rotator at the center of the inelastic pressing portion. A fixing device characterized by the above. The fixing device according to claim 1,
A fixing device having a support portion for supporting the elastic pressing portion and the inelastic pressing portion. The fixing device according to claim 1,
The fixing device according to claim 1, wherein the inelastic pressing portion integrally forms a support portion that supports the elastic pressing portion. The fixing device according to claim 1,
The length of the heating unit in the axial direction of the heating rotator is shorter than the length of the inelastic pressing unit in the direction of the axis of pressurizing rotator,
The fixing device, wherein the heating unit is located inside the inelastic pressing unit when viewed from a direction orthogonal to the heating rotating body axis and the pressure rotating body axis. The fixing device according to claim 1,
The heating part is
A heating part for passing small size paper that heats the central part other than the end part in the axial direction of the heating rotator,
A fixing device comprising: a heating section for passing large-size sheets that heats an end portion and a central portion in the axial direction of the heating rotator. The fixing device according to claim 3.
Based on the respective thermal conductivities of the end portion and the central portion of the inelastic pressing portion, the output of the heating portion when heating the axial end portion and the central portion of the heating rotating body is set. A fixing device having a control unit for performing the above operation. The fixing device according to claim 3.
Based on the respective thermal conductivities of the end part and the central part of the inelastic pressing part, the contact pressures of the end part and the central part of the heating rotator in the axial direction with respect to the pressurizing rotator are set. A fixing device having a control unit.   An image forming apparatus comprising the fixing device according to claim 1.

Images