JP2019091028A - Fixing device and image forming apparatus - Google Patents

Abstract

To provide a fixing device and an image forming apparatus that can reduce the rise time of the surface temperature of a heating unit, compared with a configuration in which a low heat conduction member is partially arranged.SOLUTION: A fixing device comprises: a circulating belt member 611; a pressing unit that is in contact with the belt member and applies pressure to a recording medium moving between the belt member and pressing unit; a heat source 612 having a substrate 612A, and a resistance heating element that is formed on a surface of the substrate to extend in the longitudinal direction of the substrate and heats an inner surface of the belt member; a low heat conduction part 613 that is arranged on a surface of the heat source 612 on the opposite side of a surface close to the belt member; and a high heat conduction part 614 that is arranged on a surface of the low heat conduction part on the opposite side of a surface close to the heat source. The heat source is arranged in contact with the low heat conduction part and not in contact with the high heat conduction part.SELECTED DRAWING: Figure 4

Description

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

  A heating member having a heater, a heat insulating supporting member for supporting the heater and preventing heat radiation, a film provided slidably in contact with the heater, and a pressing member disposed on the heating member side so as to be capable of pressurizing A heating device for conveying the sheet between the film and the pressing member and heating while pressing the sheet, wherein the high thermal conductive member is interposed between the heater and the heat insulating support member. It is known (patent document 1).

  A fixing film which is driven to travel, and a heating member and a pressing member which are in pressure contact with each other across the fixing film; and the fixing film of the fixing nip portion formed by the pressure of the heating member and the pressing member with the fixing film interposed therebetween; By supplying a recording material carrying an unfixed toner image to the pressing member and moving it through the fixing nip with the traveling fixing film, heat energy is given to the recording material from the heating body through the fixing film. Is a fixing device that heats and fixes a visible image, and a high thermal conductivity member having a thermal conductivity of 100 kcal / mhr ° C. or higher is provided on the opposite side of the heating body to the contact surface with the fixing film. A fixing device is also known (Patent Document 2).

Japanese Patent Application Laid-Open No. 11-84919 Unexamined-Japanese-Patent No. 5-289555

  The present invention provides a fixing device and an image forming apparatus capable of shortening the rise time of the surface temperature of the heat generating portion as compared with the configuration in which the low heat conductive member is partially disposed.

In order to solve the above-mentioned subject, the fixing device according to claim 1,
A circulating belt member,
Pressing means for pressing the recording medium contacting the belt member and moving between the belt member and the belt member;
A substrate, and a heating unit that heats the inner surface of the belt member, the heating unit being formed on the surface of the substrate so as to extend in the longitudinal direction of the substrate;
A low heat conducting portion disposed on the side opposite to the side near the belt member of the heating means;
And a high thermal conductivity portion disposed on a surface opposite to the surface close to the heating means of the low thermal conductivity portion;
The heating means is disposed so as to be in contact with the low thermal conductivity portion and not to be in contact with the high thermal conductivity portion.
It is characterized by

According to a second aspect of the present invention, in the fixing device according to the first aspect,
The width of the low thermal conductivity portion in the conveyance direction of the recording medium is wider than the width of the heating unit in the conveyance direction of the recording medium.
It is characterized by

The invention according to claim 3 is the fixing device according to claim 1 or 2
The low heat conducting portion is longer in the longitudinal direction than the heat generating portion of the heating means.
It is characterized by

According to a fourth aspect of the present invention, in the fixing device according to the third aspect,
The low thermal conductivity portion is shorter than the base of the heating means in the longitudinal direction.
It is characterized by

The invention according to claim 5 is the fixing device according to any one of claims 1 to 4 in which
The width of the high thermal conductivity portion in the conveyance direction of the recording medium is wider than the width of the heating unit in the conveyance direction of the recording medium.
It is characterized by

The invention according to claim 6 is the fixing device according to any one of claims 1 to 5,
The thickness of the high thermal conductivity portion is such that both outer sides of the heat generating portion are thick in the conveyance direction of the recording medium of the high thermal conductivity portion.
It is characterized by

The invention according to claim 7 is the fixing device according to claim 6.
The thickness of the low thermal conductivity portion is thicker at a central portion in the conveyance direction of the recording medium of the low thermal conductivity portion.
It is characterized by

The invention according to claim 8 is the fixing device according to any one of claims 1, 2, 3, 5 to 6, wherein
The low heat conducting portion is in contact with the entire surface of the heating means.
It is characterized by

The invention according to claim 9 is the fixing device according to claim 1.
The width of the low thermal conductivity portion in the transport direction of the recording medium is wider than the width of the high thermal conductivity portion in the transport direction of the recording medium,
It is characterized by

In order to solve the above-mentioned subject, the fixing device according to claim 10,
A circulating belt member,
Pressing means for pressing the recording medium contacting the belt member and moving between the belt member and the belt member;
A substrate, and a heating unit that heats the inner surface of the belt member, the heating unit being formed on the surface of the substrate so as to extend in the longitudinal direction of the substrate;
A low heat conducting portion disposed on the side opposite to the side near the belt member of the heating means;
And a high thermal conductivity portion disposed on a surface opposite to the surface close to the heating means of the low thermal conductivity portion;
In the surface of the high thermal conductivity portion in contact with the low thermal conductivity portion, a recess is not formed over the entire area in the longitudinal direction,
It is characterized by

In order to solve the above-mentioned subject, the fixing device according to claim 11,
A circulating belt member,
Pressing means for pressing the recording medium contacting the belt member and moving between the belt member and the belt member;
A substrate, and a heating unit that heats the inner surface of the belt member, the heating unit being formed on the surface of the substrate so as to extend in the longitudinal direction of the substrate;
A low heat conducting portion disposed on the side opposite to the side near the belt member of the heating means;
And a high thermal conductivity portion disposed on a surface opposite to the surface close to the heating means of the low thermal conductivity portion;
The surface of the heating means opposite to the surface close to the belt member is disposed so as to be in contact with the low heat conduction portion and not to be in contact with the high heat conduction portion.
It is characterized by

The invention according to claim 12 is the fixing device according to any one of claims 1 to 11:
The low heat conducting part is a heat resistant synthetic resin or an air layer,
It is characterized by

In order to solve the above-mentioned subject, the image forming apparatus according to claim 13 is
An image forming unit for forming an image on a recording medium;
The fixing device according to any one of claims 1 to 12, which fixes the image on the recording medium on which the image is formed by the image forming unit.
It is characterized by

  According to the inventions of claims 1 and 13, the rise time of the heat generating portion surface temperature can be shortened as compared with the configuration in which the low heat conduction member is disposed in part.

  According to the second aspect of the present invention, the heating means and the high thermal conductivity portion can be prevented from coming in contact with each other in the width direction of the heating means.

  According to the third aspect of the present invention, even in the longitudinal direction of the heating means, it is possible to prevent the portion corresponding to the heat generating portion of the heating means from coming into contact with the high thermal conductivity portion.

  According to the fourth aspect of the present invention, it is possible to suppress the heat insulation of the area where the heat insulation is unnecessary in the longitudinal direction of the heating means.

  According to the fifth aspect of the present invention, it is possible to suppress the temperature rise in the non-sheet passing area.

  According to the sixth aspect of the present invention, it is possible to suppress the temperature rise in the non-sheet passing area.

  According to the seventh aspect of the invention, it is possible to suppress the temperature rise in the non-sheet passing area.

  According to the sixth aspect of the present invention, the heat generation distribution on the surface of the heat generating portion can be made uniform, as compared with a configuration in which the thickness of the high thermal conductivity portion changes.

  According to the seventh aspect of the invention, it is possible to suppress the temperature rise in the non-sheet passing area.

  According to the eighth aspect of the present invention, the pressure distribution in the contact area between the pressurizing means and the heating means can be made uniform.

  According to the ninth aspect of the present invention, the high thermal conductivity portion can be configured not to contact the heating means more reliably.

  According to the invention as set forth in claim 10, compared with the configuration in which the recess is formed in the entire area in the longitudinal direction on the surface of the high thermal conductivity portion in contact with the low thermal conductivity portion, the area contacting the low thermal conductivity portion of the high thermal conductivity portion The heat generation distribution on the surface of the heat generating portion can be made more uniform.

  According to the invention as set forth in claim 11, the rise time of the surface temperature of the heat generating portion can be shortened as compared with the configuration in which the surface opposite to the surface close to the belt member in the heating means is in contact with the high thermal conductivity portion. . can do.

  According to the twelfth aspect of the present invention, the rise time of the heat generating portion surface temperature can be shortened.

FIG. 2 is a schematic cross-sectional view showing an internal configuration of the image forming apparatus. FIG. 1 is a schematic cross-sectional view showing the entire configuration of a fixing device. It is a plane schematic diagram which shows the structure of a heating source. It is a cross-sectional schematic diagram explaining the one aspect | mode of a structure of a heating module. It is a longitudinal cross-section schematic diagram explaining the structure of the longitudinal direction of a heating module. It is a cross-sectional schematic diagram explaining the other aspect of a structure of a heating module. It is a perspective view explaining the contact of a constant heat conduction part and a high heat conduction part. (A) is explanatory drawing explaining the heat transfer at the time of standup in a fixing device, (b) is explanatory drawing explaining the heat transfer at the time of printing. It is a cross-sectional schematic diagram which shows the structure of the heating module which has the low thermal-conduction part which concerns on the modification 1. FIG. It is a cross-sectional schematic diagram which shows the structure of the heating module which has the high heat conduction part which concerns on the modification 2. As shown in FIG. It is a cross-sectional schematic diagram which shows the structure of the heating module which has the low thermal-conduction part which concerns on the modification 3. FIG. It is a cross-sectional schematic diagram which shows the structure of the heating module which has the low thermal-conduction part which concerns on the modification 4. FIG. FIG. 6 is a view showing the relationship between the rise time of the fixing device and the thickness of the low heat conducting portion. FIG. 7 is a schematic longitudinal sectional view of the heating module of the fixing device according to Embodiment 2; FIG. 7 is a view showing the relationship between the temperature of the fixing belt at the non-sheet passing portion and the thickness of the high heat conduction portion in the fixing device according to Embodiment 2. FIG. 10 is a schematic cross-sectional view of a heating module of the fixing device according to Embodiment 3. FIG. 13 is a schematic longitudinal sectional view of the heating module of the fixing device according to Embodiment 3; It is a cross-sectional schematic diagram of the heating module of the fixing device which concerns on a comparative example. It is a longitudinal cross-section schematic diagram of the longitudinal direction of the heating module of the fixing device concerning a comparative example.

Next, the present invention will be described in more detail by way of embodiments and specific examples with reference to the drawings, but the present invention is not limited to these embodiments and specific examples.
Moreover, in the description using the following drawings, it should be noted that the drawings are schematic, and that the ratio of each dimension is different from the actual one, and is necessary for the explanation to facilitate understanding. The illustration other than the members is appropriately omitted.
In order to facilitate understanding of the following description, in the drawings, the left-right direction is taken as the X-axis direction, the front-rear direction as the Y-axis direction, and the vertical direction as the Z-axis direction.

First Embodiment
(1) Overall Configuration and Operation of Image Forming Apparatus FIG. 1 is a schematic sectional view showing an internal configuration of an image forming apparatus 1 according to the present embodiment.
The overall configuration and operation of the image forming apparatus 1 will be described below with reference to the drawings.

  The image forming apparatus 1 is configured to include a control device 10, a sheet feeding device 20, a photosensitive unit 30, a developing device 40, a transfer device 50, a fixing device 60, and a power supply device 70. On the upper surface (Z direction) of the image forming apparatus 1, a discharge tray 1a is formed in which the sheet on which the image is recorded is discharged and stored.

  The control device 10 includes an image forming apparatus control unit 11 that controls the operation of the image forming apparatus 1, a controller unit 12 that prepares image data according to a print processing request, and an exposure control unit 13 that controls lighting of the exposure head LH. Have.

  The controller unit 12 converts print information input from an external information transmission apparatus (for example, a personal computer or the like) into image information for forming a latent image and outputs a drive signal to the exposure head LH at a preset timing. . The exposure head LH of the present embodiment is configured of an LED head in which a plurality of light emitting elements (LEDs: Light Emitting Diodes) are linearly arranged along the main scanning direction.

  At the bottom of the image forming apparatus 1, a sheet feeding device 20 is provided. The sheet feeding device 20 includes a sheet stacking plate 21, and a plurality of sheets P as recording media are stacked on the upper surface of the sheet stacking plate 21. The sheet P stacked on the sheet stacking plate 21 and whose position in the width direction is determined by the restriction plate (not shown) is drawn forward one by one from the upper side by the sheet extracting portion 22 (X direction). The sheet is conveyed to the nip 23

  The photosensitive unit 30 is provided in parallel with each other above the sheet feeding device 20 (in the Z direction), and includes a photosensitive drum 31 as an image holding member that is rotationally driven. The charging roller 32, the exposure head LH, the developing device 40, the primary transfer roller 52, and the cleaning blade 34 are disposed along the rotational direction of the photosensitive drum 31. A cleaning roller 33 for cleaning the surface of the charging roller 32 is disposed opposite to and in contact with the charging roller 32.

The developing device 40 has a developing housing 41 in which a developer composed of toner and carrier is accommodated. In the developing housing 41, a developing roller 42 as a developer holding member disposed opposite to the photosensitive drum 31, and the developer is stirred and conveyed to the developing roller 42 side obliquely downward on the back side of the developing roller 42. A pair of augers 44, 45 are provided. A layer regulating member 46 for regulating the layer thickness of the developer is disposed close to the developing roller 42.
The developing devices 40 are similarly configured except for the developer contained in the developing housing 41, and form toner images of yellow (Y), magenta (M), cyan (C) and black (K) respectively. .

  The surface of the rotating photosensitive drum 31 is charged by the charging roller 32, and an electrostatic latent image is formed by the latent image forming light emitted from the exposure head LH. The electrostatic latent image formed on the photosensitive drum 31 is developed as a toner image by the developing roller 42.

  The transfer device 50 includes an intermediate transfer belt 51 on which the toner images of the respective colors formed on the photosensitive drums 31 of the respective photosensitive unit 30 are multiply transferred, and an intermediate transfer belt of the respective color toner images formed on the respective photosensitive units 30. A primary transfer roller 52 that sequentially transfers (primary transfer) to 51, and a secondary transfer roller 53 that collectively transfers (secondary transfer) toner images on the intermediate transfer belt 51 onto the sheet P. There is.

  Each color toner image formed on the photosensitive drum 31 of each photosensitive unit 30 is transferred to the intermediate transfer belt 51 by the primary transfer roller 52 to which a predetermined transfer voltage is applied from the power supply device 70 controlled by the image forming apparatus control unit 11. Electrostatic transfer (primary transfer) is sequentially performed on the upper side, and a superimposed toner image in which toners of respective colors are superimposed is formed.

  The superimposed toner image on the intermediate transfer belt 51 is conveyed to a region (secondary transfer portion TR) in which the secondary transfer roller 53 is disposed as the intermediate transfer belt 51 moves. When the superimposed toner image is conveyed to the secondary transfer portion TR, the sheet P is supplied from the sheet feeding device 20 to the secondary transfer portion TR in accordance with the timing. Then, a predetermined transfer voltage is applied to the secondary transfer roller 53 from the power supply device 70 controlled by the image forming apparatus control unit 11, the sheet P is sent out from the registration roller pair 23, and the sheet P guided by the conveyance guide The multiple toner images on the transfer belt 51 are collectively transferred.

  The residual toner on the surface of the photosensitive drum 31 is removed by the cleaning blade 34 and collected in a waste developer storage portion. The surface of the photosensitive drum 31 is recharged by the charging roller 32. Incidentally, the residue which can not be completely removed by the cleaning blade 34 and is attached to the charging roller 32 is captured and accumulated on the surface of the cleaning roller 33 which rotates in contact with the charging roller 32.

  The fixing device 60 includes a heating module 61 including a heating source 612 and a pressure module 62. The pressure contact area of the heating module 61 and the pressure module 62 forms a fixing nip N (fixing area).

The sheet P on which the toner image has been transferred in the transfer device 50 is conveyed to the fixing device 60 via the conveyance guide in a state where the toner image is not fixed. The sheet P conveyed to the fixing device 60 is fixed in a toner image by the action of pressure bonding and heating by the pair of heating modules 61 and the pressure module 62.
The sheet P on which the fixed toner image is formed is discharged from the discharge roller pair 69 to the discharge tray 1 a on the upper surface of the image forming apparatus 1 through the conveyance roller pair 68.

(2) Configuration of Fixing Device 60 FIG. 2 is a schematic cross sectional view showing the entire configuration of the fixing device 60, FIG. 3 is a schematic plan view showing the configuration of the heating source 612, and FIG. 5 is a longitudinal cross-sectional schematic view explaining the configuration of the heating module 61 in the longitudinal direction, FIG. 6 is a schematic cross-sectional view explaining the other aspect of the configuration of the heating module 61, and FIG. 8A is an explanatory view for explaining the heat transfer at the time of start-up in the fixing device 60, and FIG. 8B is an explanatory view for explaining the heat transfer at the time of printing. .

(2.1) Overall Configuration of Fixing Device The fixing device 60 includes a heating module 61 as an example of a heating unit and a pressure module 62 as an example of a pressure unit.

The heating module 61 includes a fixing belt 611 as an example of a belt member used for fixing a toner image on the sheet P, and a heating source 612 with which the inner surface of the fixing belt 611 contacts and slides. It is made of a heat-resistant synthetic resin such as polyethylene terephthalate (PET) through a low heat conductive portion 613 made of a heat resistant synthetic resin material and a high heat conductive portion 614 made of aluminum oxide which is a heat resistant / electrical insulating material. It is held by a holding member 617. The holding member 617 also has the function of a guide for guiding the rotation of the fixing belt 611 as well as the holding function of the heat source 612.
The holding member 617 is supported by a supporting member 618 which is made of metal and has high bending strength.

The pressure module 62 includes a pressure roller 621 and a pressure mechanism (not shown) including a pressure spring (not shown) for pressing the pressure roller 621 against the heating module 61.
The pressure roller 621 further includes, for example, a cylindrical core member 622 made of metal, and a heat-resistant elastic layer 623 (for example, a silicone rubber layer, a fluorine rubber layer, etc.) coated on the outer peripheral surface of the core member 622. If necessary, a surface release layer 624 made of, for example, a heat resistant resin coating such as PFA or a heat resistant rubber coating is laminated and configured.

  The pressure roller 621 receives power from a motor (not shown) and rotates clockwise (in the direction of arrow R in FIG. 2) in the drawing. When the pressure roller 621 rotates, the fixing belt 611 follows and rotates in the counterclockwise direction (the direction of arrow R in FIG. 2). The sheet P is nipped and conveyed by the fixing nip N, whereby the toner image of the sheet P with which the surface of the fixing belt 611 is in contact is heated and fixed to the sheet P by the heat of the heating source 612 being transmitted.

The fixing belt 611 is a multi-layered belt member including a base material layer, an elastic layer for improving the fixing property of the toner image, and a surface release layer coated on the uppermost layer. As a base material layer, a resin material etc. (for example, polyimide resin) with a thickness of 50 micrometers-200 micrometers are used, for example. The elastic layer is formed by laminating toners of respective colors on the sheet P to be fixed, and the fixing belt follows the unevenness of the toner image on the sheet P in order to uniformly supply heat to the entire toner image at the nip portion. It is preferable that the surface of the surface 611 is deformed. For example, silicone rubber having a thickness of 100 μm to 600 μm and a hardness of 10 ° to 30 ° (JIS-A) is used. In the case of a black and white image forming apparatus, the elastic layer can be omitted.
For example, PFA (tetrafluoroethylene perfluoroalkyl vinyl ether polymer) is used to weaken the adhesion of the sheet P to the fixing belt 611 by weakening the adhesion with the toner melted on the sheet P. PTFE (polytetrafluoroethylene), silicone copolymers, or composite layers thereof are used.

  Inside the fixing belt 611, as shown in FIG. 3, a heating source 612 extending along the moving direction (X direction) of the fixing belt 611 and the width direction (Y direction) of the fixing belt 611 is provided. . The heating source 612 is a sheet-like heating element extending in the longitudinal direction, and the heating source 612 heats the fixing belt 611 to a predetermined temperature.

  The heating source 612 includes, for example, a base 612A formed of stainless steel (SUS) or ceramic, and a resistance heating element 612B mainly composed of a silver-palladium (Ag-Pd) alloy formed on the base 612A. A conductive pattern 612C mainly composed of a silver-palladium (Ag-Pd) alloy, an insulator (in the present embodiment, a glass) insulator 612D covering the resistance heating element 612B and the conductive pattern 612C, silver-palladium (Ag-Pd) ) Has a feed electrode 612E made of a good conductor film made of an alloy, and is connected to a power supply (not shown) to receive a feed.

  The low heat conducting portion 613 is in contact with the surface of the heat source 612 opposite to the surface in contact with the inner surface of the fixing belt 611. The low thermal conductive portion 613 is formed of a heat resistant synthetic resin material such as polyphenylene terephthalate (PET), polyphenylene sulfide (PPS), liquid crystal polymer (LCP), polyamide imide (PAI), polyetheretherketone (PEEK), etc. ing. The low thermal conductivity portion 613 suppresses thermal conduction to the high thermal conductivity portion 614 described later, thereby suppressing the deterioration of the rising time of the heating source 612 at the start of the energization.

  The high thermal conductivity portion 614 is in contact with the surface of the low thermal conductivity portion 613 opposite to the surface in contact with the heating source 612. The high thermal conductivity portion 614 is made of, for example, an aluminum plate (JIS A1050) with a thickness of 5 mm to 10 mm, and moves the amount of heat of the heating source 612 in the longitudinal direction to reduce temperature consumption and power consumption across the entire base 612A. Have an effect.

As shown in FIGS. 2 and 4, a thermistor 615 is provided in contact with the surface of the high thermal conductivity portion 614 opposite to the low thermal conductivity portion 613, and penetrates the high thermal conductivity portion 614 and the low thermal conductivity portion 613. A thermostat 616 is disposed in contact with the surface of the heat source 612 opposite to the resistance heating element 612B.
The thermistor 615 and the thermostat 616 are biased by a coil spring SR (see FIG. 2) to abut the high thermal conductivity portion 614 and the heating source 612 to obtain stable thermal response.

The temperature of the heat source 612 is detected by the thermistor 615, and the heat source 612 is temperature-controlled to a predetermined target set temperature based on the detected temperature, and the fixing belt 611 is heated to that temperature.
Specifically, based on the detected temperature of the thermistor 615 and the set temperature of the heating source 612, for example, the image forming apparatus 1 performs feedback control on input power continuously so that the heating source 612 reaches the target temperature from the difference. Perform PI control to calculate the power to be supplied. Furthermore, it converts into the control level of the phase angle (phase control) and wave number (wave number control) corresponding to the supplied electric power, and controls the triac (not shown) according to the control condition.

  When the heating module 61 is in a heat generation state beyond the steady state due to a failure of the power control unit, such as a short circuit of the TRIAC, the thermostat 616 operates to cut off the power supply to the heating source 612. When the temperature detected by the thermistor 615 detects a predetermined temperature or higher, the relay is deenergized to cut off the power supply to the heating source 612.

(2.2) Configuration of low thermal conductivity portion and high thermal conductivity portion The low thermal conductivity portion 613 has its one surface 613a in contact with the horizontally long rectangular parallelepiped base material 612A of the heating source 612 as shown in FIG. 4 and FIG. It is arranged. Specifically, as shown in FIG. 4, the low thermal conductivity portion 613 has the width W 0 of the base 612 A so that the width W covers the base 612 A of the heating source 612 in the width direction (X direction) of the heating source 612. As shown in FIG. 5, the length L is longer than the length L 0 of the resistance heating element 612 B of the heating source 612, and the heating source 612 and the high-temperature heat The configuration is such that the conductive portion 614 does not contact.

FIG. 6 shows another aspect of the configuration in which the heat source 612 and the high thermal conductivity portion 614 do not come in contact with each other. As shown in FIG. 6, the surface (base material 616A) opposite to the surface (insulator 612D) close to the fixing belt 611 in the heating source 612 is in contact with the low thermal conductivity portion 613.
In the high thermal conductivity portion 614, as shown in FIG. 6, both outer sides (614a shown in FIG. 6) of the resistance heating element 612B are formed thick in the direction (width direction) intersecting the longitudinal direction of the heating source 612, It contacts with both ends 612Aa of base 612A of heating source 612, and the whole does not contact heating source 612.
Thus, the rise time of the surface temperature of the heat generating portion of the heat source 612 can be shortened as compared with a configuration in which the surface on the opposite side to the surface near the fixing belt 611 in the heat source 612 contacts the high thermal conductivity portion 614.

Further, as shown in FIG. 5 and FIG. 7, the high thermal conductivity portion 614 has no recess formed in the entire area in the longitudinal direction on the surface of the high thermal conductivity portion 614 in contact with the low thermal conductivity portion 613. Specifically, the upper surface of the low thermal conductivity portion 613 of the high thermal conductivity portion 614 (on the opposite side to the heating source 612, except for the through holes 616a passing through the high thermal conductivity portion 614 and the low thermal conductivity portion 613 for mounting the thermostat 616. No concave portion is formed on the surface (see the shaded portion in FIG. 7) which is in contact with the surface, and the entire surface is in contact with the low heat conducting portion 613.
As a result, the area of the high thermal conductivity portion 614 in contact with the low thermal conductivity portion 613 is increased compared to the configuration in which the recess is formed on the entire surface in the longitudinal direction on the surface of the high thermal conductivity portion 614 in contact with the low thermal conductivity portion 613. The heat generation distribution on the surface of the heat generating portion of the heat source 612 can be made more uniform.

  As described above, by arranging the heating source 612 to be in contact with the low thermal conductivity portion 613 and not to be in contact with the high thermal conductivity portion 614, as schematically shown in FIG. The low thermal conductivity portion 613 suppresses thermal conduction to the high thermal conductivity portion 614 (see arrow H2 in FIG. 8A), and the heat generated by the resistance heating element 612B of the heating source 612 is mainly transferred through the fixing belt 611. The pressure is transmitted to the pressure roller 621 side (see arrow H1 in FIG. 8A). As a result, the heat conduction to the high thermal conductivity portion 614 is suppressed, and the deterioration of the rise time at the start of the energization of the heating source 612 is suppressed.

Further, at the time of printing after rising, as schematically shown in FIG. 8B, the heat generated by the resistance heating element 612B of the heating source 612 is also transmitted to the high thermal conductivity portion 614 (FIG. 8B) Middle arrow H2). The high thermal conductivity portion 614 is wider than the low thermal conductivity portion 613 so as to cover the low thermal conductivity portion 613 in the width direction (X direction) of the thermal source 612, and as shown in FIG. And the resistance heating element 612B of the heating source 612 is formed longer.
As a result, the high thermal conductivity portion 614 covers the entire low thermal conductivity portion 613, and the amount of heat of the thermal source 612 transmitted through the low thermal conductivity portion 613 is moved in the longitudinal direction, whereby the non-sheet-passing of the thermal source 612 is performed. Excessive temperature rise in the region can be suppressed.

  The low thermal conductivity portion 613 is formed shorter than the base 612A in the longitudinal direction (Y direction) of the heating source 612. Thereby, the heat insulation of the area | region where heat insulation is unnecessary in the longitudinal direction of the heat source 612 can be suppressed.

"Modification 1"
FIG. 9 is a schematic cross-sectional view showing the configuration of a heating module 61A having a low thermal conductivity portion 613A according to the first modification.
As shown in FIG. 9, in the direction (width direction) intersecting the longitudinal direction of the heat source 612, the low heat conducting portion 613A is formed such that its central portion is thicker than its both ends in the thickness direction. Thus, the heat generated by the resistance heating element 612B of the heating source 612 is easily transmitted from the central portion where the low thermal conductive portion 613A is thickly formed to the high thermal conductive portion 614, thereby suppressing an increase in rise time at the start of energization. can do.

"Modification 2"
FIG. 10 is a schematic cross-sectional view showing the configuration of a heating module 61B having a high thermal conductivity portion 614A according to the second modification.
In the high thermal conductivity portion 614A, both outer sides (614Aa shown in FIG. 8) of the resistance heating element 612B are formed thick in the direction (width direction) intersecting the longitudinal direction of the heating source 612. The heat generated by the resistance heating element 612B of the heating source 612 is easily transferred upward through the low thermal conductivity portion 613, and the region of the high thermal conductivity portion 614A facing the resistance heating element 612B (614Ab illustrated in FIG. 10). The thinner the thickness, the more the rise time is suppressed. On the other hand, it is known that when the thickness of the high thermal conductivity portion 614A is thin, it is difficult to move the heat quantity of the heating source 612 in the longitudinal direction, and the effect of temperature equalization across the longitudinal direction becomes low.

  The high thermal conductivity portion 614A according to the modification 2 is formed by increasing the thickness of both outer sides (614Aa) of the resistance heating element 612B in the direction (width direction) intersecting the longitudinal direction of the heating source 612, at the start of energization. The heat quantity of the heat source 612 can be easily moved in the longitudinal direction while suppressing an increase in the rise time of the sheet, thereby suppressing an excessive temperature rise in the non-sheet-passing area.

"Modification 3"
FIG. 11 is a schematic cross-sectional view showing the configuration of a heating module 61C having a low thermal conductive portion 613B according to the third modification.
The low thermal conductivity portion 613 B is formed as an air layer provided between the heat source 612 and the high thermal conductivity portion 614 as shown in FIG. The air layer has lower thermal conductivity than heat-resistant synthetic resin materials such as PET (polyphenylene terephthalate) and LCP (liquid crystal polymer), and suppresses the thermal conduction from the heating source 612 to the high thermal conductivity portion 614 to reduce cost. Thus, it is possible to suppress the deterioration of the rise time of the heating source 612 at the start of energization.

"Modification 4"
FIG. 12 is a schematic cross-sectional view showing the configuration of a heating module 61D having a low thermal conductive portion 613C according to the fourth modification.
As shown in FIG. 12, the low thermal conductivity portion 613C has a width W1 in the conveyance direction (X direction) of the sheet P as a recording medium that is greater than the width W2 in the conveyance direction (X direction) of the high thermal conductivity portion 614 It is widely formed. That is, the low thermal conductivity portion 613C made of a heat resistant synthetic resin material disposed between the heating source 612 and the high thermal conductivity portion 614 is wider than the high thermal conductivity portion 614 even in the width direction intersecting the longitudinal direction (Y direction) ( It is arrange | positioned so that it may become W1> W2).
Thus, the high thermal conductivity portion 614 can be more reliably prevented from coming into contact with the heating source 612 which is the heating means.

Example 1
FIG. 13 is a view showing the relationship between the rise time of the fixing device 60 and the thickness of the low heat conducting portion 613. As shown in FIG.
In the heating module 61 shown in FIG. 5, the heating source 612 has a base material 612A made of alumina and having a thickness of 1 mm, a length of 250 mm in the longitudinal direction, and a length (width) of 7 mm in the direction orthogonal to the longitudinal direction. is there. The resistance heating element 612B is formed by coating an electrical resistance material consisting of silver palladium by screen printing with a thickness of about 10 μm, a length in the longitudinal direction of 216 mm, and a width of 1.0 mm, and glass is used as the insulator 612D. Coated.

The high thermal conductivity portion 614 is made of an aluminum plate (JIS A1050), and has a thickness of 10 mm, a length of 250 mm in the longitudinal direction, and a length (width) of 7 mm in the direction orthogonal to the longitudinal direction.
The low thermal conductivity portion 613 has a length of 250 mm in the longitudinal direction and a length (width) 7 mm in the direction orthogonal to the longitudinal direction, and has a thickness of 0 mm (without the low thermal conductivity portion 613; the high thermal conductivity portion 614 is the base material of the heating source 612 The configuration in contact with 612 A) was changed to 2.0 mm every 0.1 mm. Further, as a material of the low thermal conductive portion 613, two types of PET (polyphenylene terephthalate) and PI (polyimide) were used.

A power of 850 W was applied to the heating source 612 of the fixing device 60 having such a configuration, and the rise time t was measured as the time until the surface temperature of the fixing belt 611 became the fixable temperature.
The deterioration of the rise time t can be suppressed in the PI (polyimide) resin having a low thermal conductivity of the low thermal conductive portion 613. In addition, the deterioration of the rise time t becomes shorter as the thickness increases, and the high thermal conductivity portion 614 is heated if the thickness is 1.0 mm or more, whichever material is PET (polyphenylene terephthalate) or PI (polyimide). Compared with the case where the source 612 was not in contact (rise time t ₀ = 3.0 sec), the deterioration was only 0.1 sec.

(Example 2)
FIG. 14 is a schematic longitudinal sectional view of the heating module 61 of the fixing device 60 according to the second embodiment, and FIG. 15 is the temperature of the fixing belt 611 in the non-sheet passing portion S of the fixing device 60 and the thickness of the high heat conducting portion 614 FIG.
In the fixing device 60 shown in FIG. 14, the heating source 612 is a base 612A made of alumina, having a thickness of 1 mm, a length of 250 mm in the longitudinal direction, and a length (width) of 7 mm in the direction orthogonal to the longitudinal direction. is there. The resistance heating element 612B is formed by coating an electrical resistance material consisting of silver palladium by screen printing with a thickness of about 10 μm, a length in the longitudinal direction of 216 mm, and a width of 1.0 mm, and glass is used as the insulator 612D. Coated.

The low thermal conductive portion 613 is made of PI (polyimide) and has a thickness of 0.5 mm, a length of 250 mm in the longitudinal direction, and a length (width) of 7 mm in the direction orthogonal to the longitudinal direction.
The high thermal conductivity portion 614 has a length of 250 mm in the longitudinal direction and a length (width) of 7 mm in the direction orthogonal to the longitudinal direction, and the thickness is changed to 1 mm, 5 mm, and 10 mm. Further, as the material of the high thermal conductivity portion 614, two types of copper plate and aluminum plate were used as materials having different thermal conductivity.

The image forming apparatus 1 provided with the fixing device 60 having the above configuration passes 100 to 150 sheets of A5 size paper at a productivity of 25 ppm (the number of continuously printed sheets per minute), and is non-A5 size outside The surface temperature T of the fixing belt 611 at the sheet passing portion S (see S in FIG. 14) was measured.
The surface temperature T of the fixing belt 611 at the non-sheet-passing portion S was lower (the temperature rise is smaller) in the copper plate having a high thermal conductivity compared to the aluminum plate in the high thermal conductivity portion 614. The high thermal conductivity portion 614 of the copper plate having a high thermal conductivity is easy to move the heat amount of the heating source 612 in the longitudinal direction, and it is presumed that the excessive temperature rise of the non-sheet-passing portion S is suppressed.

  The surface temperature T of the fixing belt 611 at the non-sheet passing portion S decreases with the increase of the thickness of the high thermal conductivity portion 614, and when the heat resistance temperature of the fixing belt 611 is 220 ° C. If the thickness is 4.5 mm or more and the thickness is 4.5 mm or more in the high thermal conductivity portion 614 of the aluminum plate, productivity of 25 ppm or more can be realized.

(Example 3)
16 is a schematic cross-sectional view of the heating module 61 of the fixing device 60 according to the third embodiment, FIG. 17 is a schematic longitudinal cross-sectional view of the heating module 61 of the fixing device 60, and FIG. 18 is a schematic view of the fixing device 600 according to the comparative example. FIG. 19 is a schematic cross-sectional view of the heating module 610 of the fixing device 600 in the longitudinal direction.
As shown in FIGS. 18 and 19, in the fixing device 600 according to the comparative example, the low thermal conductivity portion 613 is disposed in contact with the base 612A of the thermal source 612 and contacts the thermal source 612 of the low thermal conductivity portion 613. The high thermal conductivity part is not disposed on the surface opposite to the surface.

  In any of the third embodiment and the comparative example, the heating source 612 is a substrate 612A made of alumina, having a thickness of 1 mm, a length in the longitudinal direction of 250 mm, and a length in the direction orthogonal to the longitudinal direction (width) It is 7 mm. The resistance heating element 612B is formed by coating an electrical resistance material consisting of silver palladium by screen printing with a thickness of about 10 μm, a length in the longitudinal direction of 216 mm, and a width of 1.0 mm, and glass is used as the insulator 612D. Coated.

As shown in FIGS. 16 and 17, the low thermal conductive portion 613 is made of PI (polyimide) and has a thickness of 0.5 mm, a length in the longitudinal direction of 250 mm, and a length (width) in the direction orthogonal to the longitudinal direction of 7 mm It is.
The high thermal conductivity portion 614 in the third embodiment is made of an aluminum plate (JIS A1050), has a thickness of 5 mm, a length of 250 mm in the longitudinal direction, and a length (width) of 7 mm in the direction orthogonal to the longitudinal direction.

The image forming apparatus 1 provided with the fixing device 60 having the above configuration passes 100 to 150 sheets of A5 size paper at a productivity of 25 ppm (the number of continuously printed sheets per minute), and is non-A5 size outside The surface temperature T of the fixing belt 611 at the sheet passing portion S (see S in FIG. 17 and FIG. 19) was measured.
The maximum temperature of the fixing belt 611 in the non-sheet passing portion S exceeds 250 ° C. in the comparative example, but in Example 3, it becomes 220 ° C. or less, and the temperature rise in the non-sheet passing portion S is suppressed by 30 ° C. or more Result.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus 10 ... Control apparatus 20 ... Paper feeding apparatus 30 ... Photosensitive body unit 31 ... Photosensitive drum 40 ... Development apparatus 42 ... Development roller 50 ... Transfer device 51: Intermediate transfer belt 53: Secondary transfer roller 60, 600: Fixing device 61, 61A, 61B, 61C, 61D, 610: Heating module 611: Fixing belt 612 Heat source 612A: base material 612B: insulating layer 612C: resistance heating element 612D: insulator 613: low thermal conductivity portion 614: high thermal conductivity portion 615: thermistor 616 .. · Thermostat 617 · · · Holding member 618 · · · Support member N · · · · · · fixing nip portion

Claims (13)

A circulating belt member,
Pressing means for pressing the recording medium contacting the belt member and moving between the belt member and the belt member;
A substrate, and a heating unit that heats the inner surface of the belt member, the heating unit being formed on the surface of the substrate so as to extend in the longitudinal direction of the substrate;
A low heat conducting portion disposed on the side opposite to the side near the belt member of the heating means;
And a high thermal conductivity portion disposed on a surface opposite to the surface close to the heating means of the low thermal conductivity portion;
The heating means is disposed so as to be in contact with the low thermal conductivity portion and not to be in contact with the high thermal conductivity portion.
A fixing device characterized by The width of the low thermal conductivity portion in the conveyance direction of the recording medium is wider than the width of the heating unit in the conveyance direction of the recording medium.
The fixing device according to claim 1, The low heat conducting portion is longer in the longitudinal direction than the heat generating portion of the heating means.
The fixing device according to claim 1, wherein the fixing device is provided. The low thermal conductivity portion is shorter than the base of the heating means in the longitudinal direction.
The fixing device according to claim 3, characterized in that: The width of the high thermal conductivity portion in the conveyance direction of the recording medium is wider than the width of the heating unit in the conveyance direction of the recording medium.
The fixing device according to any one of claims 1 to 4, characterized in that: The thickness of the high thermal conductivity portion is such that both outer sides of the heat generating portion are thick in the conveyance direction of the recording medium of the high thermal conductivity portion.
The fixing device according to any one of claims 1 to 5, characterized in that: The thickness of the low thermal conductivity portion is thicker at a central portion in the conveyance direction of the recording medium of the low thermal conductivity portion.
The fixing device according to claim 6, The low heat conducting portion is in contact with the entire surface of the heating means.
The fixing device according to any one of claims 1, 2, 3, 5 to 6, characterized in that The width of the low thermal conductivity portion in the transport direction of the recording medium is wider than the width of the high thermal conductivity portion in the transport direction of the recording medium,
The fixing device according to claim 1, A circulating belt member,
Pressing means for pressing the recording medium contacting the belt member and moving between the belt member and the belt member;
A substrate, and a heating unit that heats the inner surface of the belt member, the heating unit being formed on the surface of the substrate so as to extend in the longitudinal direction of the substrate;
A low heat conducting portion disposed on the side opposite to the side near the belt member of the heating means;
And a high thermal conductivity portion disposed on a surface opposite to the surface close to the heating means of the low thermal conductivity portion;
In the surface of the high thermal conductivity portion in contact with the low thermal conductivity portion, a recess is not formed over the entire area in the longitudinal direction,
A fixing device characterized by A circulating belt member,
Pressing means for pressing the recording medium contacting the belt member and moving between the belt member and the belt member;
A substrate, and a heating unit that heats the inner surface of the belt member, the heating unit being formed on the surface of the substrate so as to extend in the longitudinal direction of the substrate;
A low heat conducting portion disposed on the side opposite to the side near the belt member of the heating means;
And a high thermal conductivity portion disposed on a surface opposite to the surface close to the heating means of the low thermal conductivity portion;
The surface of the heating means opposite to the surface close to the belt member is disposed so as to be in contact with the low heat conduction portion and not to be in contact with the high heat conduction portion.
A fixing device characterized by The low heat conducting part is a heat resistant synthetic resin or an air layer,
The fixing device according to any one of claims 1 to 11, wherein the fixing device is provided. An image forming unit for forming an image on a recording medium;
The fixing device according to any one of claims 1 to 12, which fixes the image on the recording medium on which the image is formed by the image forming unit.
An image forming apparatus characterized by

Images