JP2019020651A - Heating body, fixing device, and image forming apparatus - Google Patents

Abstract

To make uniform a temperature distribution in the longitudinal direction in the beginning of heating.SOLUTION: A heater 50 comprises: a base material 50b that has thermal conductivity; heating body patterns 50a that are formed in a predetermined range in the longitudinal direction of the base material 50b; electrode parts 50e, 50f, and 50g that supply power from the outside through electrical contacts; and conductor patterns 50d that conduct the heating body patterns 50a and the electrode parts 50e, 50f, and 50g, and the heater heats a heating target material. The base material 50b is formed such that, in the longitudinal direction, the thickness in at least partial area in a non-heating area where the heating body pattern 50a is not formed is smaller than the thickness in a heating area where the heating body pattern 50a is formed.SELECTED DRAWING: Figure 5

Description

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

  Various image forming apparatuses using an electrophotographic system have been devised as image forming apparatuses such as copying machines, facsimiles, and printers, and are well-known techniques. In the image forming process, an electrostatic latent image is formed on the surface of a photosensitive drum as an image carrier based on image information, and the electrostatic latent image on the photosensitive drum is developed with toner as a developer. The developed image is transferred to a recording medium (also referred to as paper) by a transfer device to carry the image, and the unfixed toner image on the recording medium is fixed by a fixing device using pressure, heat, or the like. It is established by the process.

  In such a fixing device used in the image forming apparatus, a technique is known in which a fixing member is heated in a fixing nip portion by using a heating element having a low heat capacity and a high temperature. And it is considered that this heating element is made to have high thermal conductivity by using a high thermal conductivity member such as aluminum nitride for the substrate in order to meet the needs of high-speed productivity.

  For example, Patent Document 1 discloses that in a heating body that has a resistance layer that generates heat when energized and an electrode portion that comes into contact with an external electrical contact on a substrate surface made of aluminum nitride and heats a material to be heated. A heating body is disclosed in which at least a partial narrowed portion is formed on the substrate between the two portions.

  However, when the base material of the heating body is made highly conductive, the heat energy generated in the heating portion (heating body) of the heating body is easily transmitted to the base material, and the heat transfer in the longitudinal direction of the heating body is promoted. For this reason, in the longitudinal direction of the heating element, on the end side of the heat generation area (heating element formation area) formed in a predetermined range, immediately after the start of heating (heating initial stage, paper feeding initial stage), Heat easily moves to the non-heat-generating area on the end side (heat-generating body non-formation area), and the temperature at the end of the heat-generating area is lower than the center of the heat-generating area, and the temperature distribution in the longitudinal direction is uniform. There was a problem that it was difficult to make it easier. For example, in the initial stage of heating, the temperature may decrease by 10 ° C. or more at the inner end of the heat generating region with respect to the central portion of the heat generating region.

  In the technique of Patent Document 1, since the electrode portion has the same width as the heat generation region, heat transfer from the throttle portion to the electrode portion is easy, and the effect of preventing a temperature drop is not sufficient.

  Then, an object of this invention is to provide the heating body which can aim at equalization of the temperature distribution of the longitudinal direction in the initial stage of a heating.

  In order to achieve such an object, a heating body according to the present invention includes a base material having thermal conductivity, a heat generating portion formed in a predetermined range in the longitudinal direction of the base material, and an electrode portion that feeds power from the outside through an electrical contact. A heating part that heats the material to be heated, and the base material is a non-heating area in which the heating part is not formed in the longitudinal direction. The thickness in at least a part of the region is smaller than the thickness in the heat generating region where the heat generating portion is formed.

  According to the present invention, the temperature distribution in the longitudinal direction in the initial stage of heating can be made uniform.

1 is a schematic configuration diagram illustrating an example of an image forming apparatus. FIG. 2 is a schematic configuration diagram illustrating an example of a fixing device. It is the (A) top view of the heater which shows an example of a heating body, (B) sectional drawing. 1 is a schematic configuration diagram illustrating an embodiment of a fixing device. It is an example of (A) top view and (B) sectional view of a heater concerning a 1st embodiment. It is the (A) top view of the heater which concerns on 1st Embodiment, (B) Another example of sectional drawing. It is an example of the (A) top view of the heater which concerns on 2nd Embodiment, and (B) sectional drawing. It is another example of sectional drawing of the heater which concerns on 2nd Embodiment. It is (A) top view and (B) sectional drawing of the heater which concerns on 3rd Embodiment. It is explanatory drawing about attachment to the heater holder of the heater shown in FIG. 3, Comprising: (A) A perspective view, (B) It is sectional drawing. It is explanatory drawing about attachment to the heater holder of the heater which concerns on 1st Embodiment, Comprising: (A) A perspective view, (B) It is sectional drawing.

  Hereinafter, a configuration according to the present invention will be described in detail based on the embodiment shown in FIGS.

[First Embodiment]
(Image forming device)
FIG. 1 is a schematic configuration diagram illustrating the overall configuration of an image forming apparatus 100 that is an embodiment of an image forming apparatus according to the present invention. With reference to FIG. 1, the outline and operation of the internal configuration of the image forming apparatus 100 will be described. Here, the direct transfer type image forming apparatus will be described as an example, but it is needless to say that the image forming apparatus may adopt an intermediate transfer type.

  As shown in FIG. 1, the image forming apparatus 100 includes a paper feeding unit 2, a photosensitive drum 1 as an image carrier, a transfer unit 6, a fixing device 20, and the like.

  The paper feeding means 2 includes a paper feeding tray 3 that accommodates the recording media P in a stacked state, and a paper feeding roller 4 that feeds the recording media P accommodated in the paper feeding tray 3 one by one in order from the top. Etc. The recording medium P sent out by the paper feed roller 4 is temporarily stopped by the registration roller pair 5, and after the position deviation is corrected, it is formed on the photosensitive drum 1 at a timing synchronized with the rotation of the photosensitive drum 1. The toner image is sent to the transfer portion N by the registration roller pair 5 at a timing when the leading end of the toner image coincides with a predetermined position at the leading end of the recording medium P in the transport direction.

  Around the photosensitive drum 1, a charging roller 8 as a charging unit, a mirror 19 constituting a part of the exposure unit, a developing unit 9 including a developing roller 9 a, and a transfer unit in the order of rotation indicated by arrows. 6 and a cleaning means 7 provided with a cleaning blade 7a. Between the charging roller 8 and the developing means 9, the exposure light 1b is irradiated onto the exposure unit 1a on the photosensitive drum 1 via the mirror 19 and scanned.

  In this image forming apparatus 100, when the photosensitive drum 1 starts to rotate, the surface of the photosensitive drum 1 is uniformly charged by the charging roller 8, and the exposure light 1b is irradiated and scanned on the exposure unit 1a based on the image information. Thus, an electrostatic latent image corresponding to the image to be created is formed. The electrostatic latent image is moved to the developing means 9 by the rotation of the photosensitive drum 1, where toner is supplied to be visualized to form a toner image. The toner image formed on the photosensitive drum 1 is transferred onto the recording medium P that has entered the transfer portion N at a predetermined timing by applying a transfer bias by the transfer unit 6.

  The recording medium P carrying the toner image is conveyed toward the fixing device 20, fixed by the fixing device 20, and then discharged and stacked on a paper discharge tray.

  Residual toner remaining on the photosensitive drum 1 without being transferred at the transfer portion N reaches the cleaning means 7 as the photosensitive drum 1 rotates, and is scraped off by the cleaning blade 7 a while passing through the cleaning means 7. To be cleaned. Thereafter, the residual potential on the photosensitive drum 1 is removed by the charge eliminating means and prepared for the next image forming step.

(Fixing device and heating element)
With reference to FIG. 2 and FIG. 3, the structure which becomes a premise of the fixing device and heating body which concern on this invention is demonstrated. FIG. 2 shows an example of the fixing device 20, and is a schematic cross-sectional view in the axial direction of the pressure roller 30. 3A is a plan view of a heater 50 as a heating body provided in the fixing device 20, and FIG. 3B is a cross-sectional view of the heater 50. FIG.

  The fixing belt 21 as a fixing member is a film member having a base made of PI (polyimide) having an outer diameter of 25 mm and a thickness of 40 to 120 μm, for example. In addition, a release layer made of a fluorine-based resin such as PFA (perfluoroalkoxyalkane) or PTFE (polytetrafluoroethylene) is formed on the outermost surface layer of the fixing belt 21 in order to enhance durability and secure release properties. Is done. The thickness of the release layer is, for example, 5 to 50 μm. The base of the fixing belt 21 is not limited to polyimide, and a heat resistant resin such as PEEK (polyether ether ketone) or a metal such as Ni (nickel) or SUS can also be used.

  The pressure roller 30 as a pressure member includes, for example, a core metal 30a made of solid iron and having an outer diameter of 25 mm and an elastic layer 30b formed on the surface of the core metal 30a. Moreover, it is preferable to form the release layer 30c on the surface of the elastic layer 30b in order to improve the release property. The elastic layer 30b is made of, for example, a silicone rubber and has a thickness of 3.5 mm. The release layer 30c is a fluororesin layer having a thickness of about 40 μm, for example. The pressure roller 30 is pressed against the fixing belt 21 side by the urging means.

  The heater 50 is a heating body in which a heating element pattern 50a is formed by screen printing or the like on a ceramic plate-like base material 50b having heat resistance and electrical insulation and having a low heat capacity. The base material 50b is a long base material extending in the longitudinal direction (axial direction) of the fixing belt 21, and is made of, for example, an alumina (aluminum oxide) plate (thermal conductivity: 20 to 30 W / mk).

The heating element pattern 50a formed on the one surface side of the base material 50b is made of, for example, an electric resistance material paste such as AgPd (silver palladium) or RuO ₂ (ruthenium oxide), for example, 10 μm thick and 1 to 3 mm wide in the longitudinal direction. It is formed by coating and baking by screen printing or the like. For example, two heating element patterns 50 a are formed in parallel along the longitudinal direction of the heater 50.

  On the surface on which the heating element pattern 50a is formed, a conductor pattern 50d having a resistance lower than that of the heating element pattern 50a is formed on both ends of the heating element pattern 50a. The conductor pattern 50d is formed, for example, by applying a conductive material paste such as Ag by screen printing or the like and baking it.

  In addition, electrode portions 50e and 50f are respectively formed on one end sides of the conductor pattern 50d at the longitudinal ends of the surface on which the heating element pattern 50a is formed. In addition, an electrode portion 50g that is electrically connected to the heating element pattern 50a is formed on the end portion in the longitudinal direction opposite to the electrode portions 50e and 50f of the heating element pattern 50a via the conductor pattern 50d.

  Further, a glass layer 50c as an insulating layer is formed so as to cover the heating element pattern 50a and the conductor pattern 50d on the one surface side of the base material 50b of the heater 50, thereby ensuring the insulation of the heater 50 (FIG. 3 ( A range indicated by a dotted line in A). Note that the glass layer 50c is not limited to the example illustrated in FIG. 3, and may be any one that covers the portions other than the portions where the electrode portions 50e, 50f, and 50g are connected to the power supply connector.

  As described above, in the heater 50, an energization path is formed in the longitudinal direction of the heater 50 between the electrode part 50e and the electrode part 50g and between the electrode part 50f and the electrode part 50g.

  As shown in FIG. 2, the heater 50 comes into contact with the inner peripheral surface of the fixing belt 21 on the glass layer 50 c side, and heats the fixing belt 21 to increase the temperature of the fixing belt 21 and is conveyed to the fixing nip portion SN. The toner image T on the recording medium P is heated and fixed. In the fixing device 20, the fixing nip SN is formed by the pressure roller 30 and the heater 50 via the fixing belt 21, and the heater 50 has a function as a nip forming member.

  The heater 50 is held by a heater holder 22 as a holding member provided on the inner peripheral side of the fixing belt 21. Since the heater holder 22 is likely to be heated to high temperatures due to the heat of the heater 50, for example, the heater holder 22 is preferably formed of a resin having high heat resistance such as LCP (Liquid Crystal Polymer), thereby improving heat insulation.

  As shown in FIG. 2, the heater holder 22 does not come into contact with the base material 50b of the heater 50 on the opposite side of the portion where the heating element pattern 50a is formed, and the base material of the heater 50 on the opposite side of the non-formation portion of the heating element pattern 50a. 50b is contacted. In the example of FIG. 2, the heater 50 (base material 50b) is brought into contact with two places on the opposite side of the non-formation portion of the heating element pattern 50a. Thereby, the heat transfer amount from the heater 50 to the heater holder 22 can be suppressed, and the heat from the heater 50 can be efficiently transmitted to the fixing belt 21.

  The heater holder 22 is supported by a stay 23 as a support member provided on the inner peripheral side of the fixing belt 21. The stay 23 is supported by both side plates of the fixing device 20 at the end in the longitudinal direction, receives the pressing force of the pressure roller 30, and forms the fixing nip portion SN.

  The thermistor 24 is temperature detecting means for detecting the temperature of the heater 50. In the example of FIG. 2, the temperature on the opposite side of the heating element pattern 50a of the base material 50b is detected, but the temperature detection position is not limited to this. Based on the detected temperature detected by the thermistor 24, the control unit controls the power supplied to the heater 50, thereby controlling the temperature of the fixing belt 21 to a desired temperature. Further, at the time of passing the paper, the temperature of the fixing belt 21 is controlled to a desired temperature by appropriately applying the additional power in consideration of the heat extracted by the paper passing. Note that the control means is constituted by, for example, a microcomputer having a CPU, a ROM, a RAM, an I / O interface, and the like.

  In the fixing device 20 and the heater 50 shown in FIG. 2 and FIG. 3 described above, if the base material 50b of the heater 50 is made highly conductive, the heat energy generated in the heating element pattern 50a can be easily transmitted to the base material 50b. The heat transfer in the longitudinal direction is promoted. For this reason, in the longitudinal direction of the heater 50, on the end side of the heat generating area (formation area of the heat generating element pattern 50a), immediately after the start of heating, the non-heat generating area (heating element pattern from the heat generating area to the end side of the substrate 50b The heat easily moves to the non-formation region 50a), the temperature of the end of the heat generation region is lower than that of the central portion of the heat generation region, and the temperature distribution in the heat generation region (that is, the sheet passing range) in the longitudinal direction. It was not possible to achieve uniformization.

  Therefore, the heating element (heater 50) according to the present embodiment includes a base material (base material 50b) having thermal conductivity, and a heating part (heating element pattern 50a) formed in a predetermined range in the longitudinal direction of the base material. Heating that heats the material to be heated, which has an electrode portion (electrode portions 50e, 50f, 50g) that feeds power from the outside through an electrical contact and a conductor portion (conductor pattern 50d) that conducts the heat-generating portion and the electrode portion. The base material is such that the thickness of at least a part of the non-heat-generating region where the heat-generating portion is not formed in the longitudinal direction is smaller than the thickness of the heat-generating region where the heat-generating portion is formed. In addition, the code | symbol in embodiment and the example of application are shown in a parenthesis.

  FIG. 4 shows an example of the fixing device 20 according to the present embodiment, and is a schematic cross-sectional view in the axial direction of the pressure roller 30. FIG. 5A is a plan view of a heater 50 as an example of a heating body provided in the fixing device 20, and FIG. 5B is a cross-sectional view of the heater 50. 6A is a plan view of a heater 50 as another example of a heating element provided in the fixing device 20, and FIG. 6B is a cross-sectional view of the heater 50. FIG. The description of the same configuration as the fixing device 20 and the heater 50 shown in FIGS. 2 and 3 will be omitted as appropriate.

  The base material 50b of the heater 50 is made of a highly heat conductive material. Examples of the high thermal conductivity material include ceramic materials such as aluminum nitride (thermal conductivity: 150 to 200 W / mk) and beryllium (thermal conductivity: 280 to 330 W / mk), or SUS, aluminum, copper, and the like. It is a metal material. FIG. 5 shows a heater 50 in which the base material 50b is made of a ceramic material, and FIG. 6 shows a heater 50 in which the base material 50b is made of a metal material.

  The base material 50b is a plate-like member extending in the longitudinal direction (axial direction) of the fixing belt 21, and is, for example, a plate material having a length of 250 mm, a width of 8 mm, and a thickness of 1 mm. Here, the base material 50b is formed with a small thickness in the region where the electrode portions 50e, 50f, 50g and the conductor pattern 50d are formed.

  The heating element pattern 50a is formed by applying an electric resistance material paste of AgPd (silver palladium) with a thickness of 10 μm and a width of 1 to 3 mm by screen printing or the like in the longitudinal direction and baking. Two heating element patterns 50 a are formed in parallel along the longitudinal direction of the heater 50.

  The conductor pattern 50d is formed, for example, by applying a conductive material paste such as Ag by screen printing or the like and baking it.

  In addition, electrode portions 50e and 50f are respectively formed on one end sides of the conductor pattern 50d at the longitudinal ends of the surface on which the heating element pattern 50a is formed. In addition, an electrode portion 50g that is electrically connected to the heating element pattern 50a is formed on the end portion in the longitudinal direction opposite to the electrode portions 50e and 50f of the heating element pattern 50a via the conductor pattern 50d.

  As described above, in the heater 50, an energization path is formed in the longitudinal direction of the heater 50 between the electrode part 50e and the electrode part 50g and between the electrode part 50f and the electrode part 50g.

  Here, when the base material 50b is made of a ceramic material, as shown in FIG. 5, a glass layer as an insulating layer so as to cover the heating element pattern 50a and the conductor pattern 50d on the one surface side of the base material 50b of the heater 50. 50c is formed to ensure insulation of the heater 50 (range shown by a dotted line in FIG. 5A). Note that the glass layer 50c is not limited to the example shown in FIG. 5, and may be anything that covers the electrode portions 50e, 50f, and 50g other than the portion connected to the power feeding connector.

  On the other hand, when the base material 50b is made of a metal material, as shown in FIG. 6, a glass layer 50c as an insulating layer is provided so as to cover the heating element pattern 50a and the conductor pattern 50d on the one surface side of the base material 50b of the heater 50. Is formed (a range indicated by a dotted line in FIG. 6A), and in order to ensure insulation between the base material 50b and the heating element pattern 50a, an insulating layer 50h is provided between the base material 50b and the heating element pattern 50a. Provided. The insulating layer 50h is, for example, a glass layer having a thickness of 75 um. Thereby, the insulation of the heater 50 is ensured.

  Further, when a highly heat conductive material is used for the substrate 50b as in the heater 50 according to the present embodiment, in order to efficiently transfer the heat energy generated in the heating element pattern 50a to the fixing belt 21, FIG. As described above, it is preferable to transfer heat by bringing the base 50b side into contact with the fixing belt 21. That is, in the case of FIG. 2, the opposite surface of the heater 50 is brought into contact with the fixing belt 21. As in FIG. 2, the glass layer 50 c side may be brought into contact with the fixing belt 21.

  Further, as shown in FIG. 4, the heater holder 22 is in contact with the heater 50 in the non-formation range of the heating element pattern 50a.

  When a high thermal conductivity material is used for the base material 50b of the heater 50, the heat energy generated in the heating element pattern 50a is easily transmitted to the base material 50b. The temperature of the end portion of this is lower than that of the central portion of the heat generating region. Moreover, since the conductor pattern 50d and the electrode portions 50e, 50f, and 50g are formed in the non-heat generation region, the non-heat generation region is long in the longitudinal direction and promotes a temperature drop.

  On the other hand, in the heater 50 according to the present embodiment, as shown in FIGS. 5B and 6B, the thickness of the non-heat generating region of the base material 50b is formed thinner than the thickness of the heat generating region. doing. As a result, the heat capacity is reduced in the non-heat-generating area, so the temperature rises quickly, and the heat transfer from the end of the heat-generating area to the non-heat-generating area can be reduced, preventing the temperature drop at the end of the heat-generating area. can do.

  At this time, it is sufficient if the thickness of the base material 50b is reduced in at least a part of the non-heat-generating region, but the thickness is changed to include the formation positions of the conductor patterns 50d and the formation positions of the electrode portions 50e, 50f, and 50g. This makes it possible to minimize the heat transfer to the non-heat generating region. For example, as shown in FIGS. 5B and 6B, it is preferable to reduce the thickness of the non-heat-generating region of the base material 50b.

  Here, when the thickness of the base material 50b (thickness in the heat generation region) is 1, from the viewpoint of achieving both heat insulation and strength, the thickness of the portion where the thickness is reduced in the non-heat generation region is 0.2-0. 8 is preferable, and 0.4 to 0.6 is more preferable. In this embodiment, since the thickness of the base material 50b is 1.0 cm, the thickness in the non-heat generation region is preferably in the range of 0.2 to 0.8 cm, and is 0.4 to 0.6 cm. It is more preferable.

  According to the heater 50 according to the present embodiment, the heat energy generated in the heating element pattern 50a is efficiently transferred to the fixing belt 21, and the heat transfer to the non-heating area is suppressed, so that It is possible to prevent the temperature drop at the end portion and make the temperature distribution in the longitudinal direction uniform.

  Further, unlike the configuration in which the diaphragm is provided in the short direction of the base material 50b (Patent Document 1), the thickness in the thickness direction of the base material 50b is reduced, so that the heating element pattern 50a, the conductor pattern 50d, and the electrode portion There is no influence on the pattern formation of 50e, 50f, 50g, etc., and the degree of freedom of formation of the heating element pattern 50a, etc. can be maintained.

[Second Embodiment]
Hereinafter, other embodiment of the heating body (heater 50) which concerns on this invention is described. In addition, the description about the same point as the said embodiment is abbreviate | omitted suitably.

  FIG. 7A is a plan view of a heater 50 as a heating element included in the fixing device 20, and FIG. 7B is a cross-sectional view of the heater 50.

  The configuration of the heater 50 shown in FIG. 5 and FIG. 6 can reduce the heat transfer to the non-heat generation region, but the strength is reduced when the thickness of the base material 50b is reduced in the entire non-heat generation region. The damage risk is increased accordingly.

  Therefore, as shown in FIG. 7B, in the non-heat generation region, the base material 50b is formed by the formation portion (region b) of the conductor pattern 50d and the formation portions (region a) of the electrode portions 50e, 50f, and 50g. It is possible to prevent the strength from being lowered by changing the thickness of the film stepwise. Moreover, since the thickness of the formation part of electrode part 50e, 50f, 50g is made thinner than the thickness of the formation part of the conductor pattern 50d, it becomes possible to suppress a heat transfer more effectively.

  FIG. 8 is another example of a sectional view of the heater 50. As shown in FIG. 8, it is good also as a shape where the thickness of the base material 50b becomes small as it goes to the edge part of the base material 50b. In the example of FIG. 7, the thickness of the base material 50b is changed stepwise between the formation portion of the conductor pattern 50d and the formation portions of the electrode portions 50e, 50f, and 50g. It is good also as a shape which has the difference of the stepped thickness within an area | region.

[Third Embodiment]
FIG. 9A is a plan view of a heater 50 as a heating element provided in the fixing device 20, and FIG. 9B is a cross-sectional view of the heater 50. In the first and second embodiments, the example in which the electrode portions 50e and 50f are formed on one end side of the heating element pattern 50a and the electrode portion 50g is formed on the other end side is shown, but the heater 50 according to the third embodiment is shown. As shown in FIG. 9A, electrode portions 50e and 50f are formed on one end side of the heating element pattern 50a, the conductor pattern 50d is made conductive on the other end side, and the electrode portion is provided on one side in the longitudinal direction. It has a configuration.

  At this time, the thickness of the region a at the end where the electrode portion is not formed may be the same as the thickness of the base material 50b as the region b at the end where the electrode portion is formed. It is preferable to have a different thickness.

  That is, the side on which the electrode part is not formed can be easily warmed because the length in the longitudinal direction can be shortened compared to the side on which the electrode part is formed. Therefore, as shown in FIG. 9B, the amount of heat transfer is increased by forming the thickness of the region a where the electrode portion is not formed and the length in the longitudinal direction is shorter than the region b where the electrode portion is formed. And the longitudinal direction can be maintained at a uniform temperature.

  Thus, when the length is different at both ends of the non-heat generating region, the heater is provided with a difference in the thickness of the base material 50b at both ends according to the difference in length in the longitudinal direction of both ends. The temperature distribution in the longitudinal direction of 50 can be made uniform.

[Mounting to the heater holder]
Next, an example of attaching the heater 50 to the heater holder 22 will be described. FIG. 10 is an explanatory view of the attachment of the heater 50 having the uniform thickness of the substrate 50b shown in FIG. 3 to the heater holder 22, FIG. 10 (A) is a perspective view, and FIG. 10 (B) is attached. A sectional view in a state is shown. Moreover, FIG. 11 is explanatory drawing about the attachment to the heater holder 22 of the heater 50 (FIG. 5, FIG. 6) which concerns on 1st Embodiment, FIG. 11 (A) is a perspective view, FIG. 11 (B). Shows a cross-sectional view in an attached state. Here, the shape of the heater holder 22 shows an example different from the example shown in FIG. 4, and a configuration example in which the glass layer 50 c side of the heater 50 faces the inner peripheral side of the fixing belt 21 is shown.

  As shown in FIGS. 10 and 11, the power supply connector 25 is connected to the electrode portion of the heater 50 in order for the heater 50 to supply power to the heater 50 in a state of being stored in the storage portion 22 a of the heater holder 22.

  Here, in the accommodating portion 22a of the heater holder 22 shown in FIG. 11, the convex portion 22b having a shallow depth on the end side in accordance with a decrease in the thickness of the end portion of the base material 50b of the heater 50. Is formed. The length in the longitudinal direction of the convex portion 22b may be the same as or shorter than the length in the longitudinal direction of the region (non-heat generation region) where the thickness of the base material 50b of the heater 50 is small. . In the case of shortening, as shown in FIG. 11B, the width L4 in the longitudinal direction of the protrusion 22b is set from the viewpoint of the stability of the assembly of the power supply connector 25, the heater 50, and the heater holder 22 pressurized by a spring. It is preferable that the power supply connector 25 is longer than the width L3 in the longitudinal direction (L4> L3).

  Further, it is preferable that the longitudinal width L2 of the portion (heat generation region) where the thickness of the base material 50b of the heater 50 is large is larger than the longitudinal width L1 of the pressure roller 30 (L2> L1).

  According to the heating body described above, the structure in which the thickness of the base material in the non-heating area in the longitudinal direction of the heating body is made thinner than that in the heating area increases the temperature rise gradient in the non-heating area and generates heat. By reducing the heat transfer from the inner end of the region, the temperature distribution in the longitudinal direction in the initial stage of heating can be made uniform.

  The above-described embodiment is a preferred embodiment of the present invention, but is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Paper feed means 3 Paper feed tray 4 Paper feed roller 5 Registration roller pair 6 Transfer means 7 Cleaning means 7a Cleaning blade 8 Charging roller 9 Developing means 9a Developing roller 19 Mirror 20 Fixing device 21 Fixing belt 22 Heater holder 22a Accommodating Portion 22b Protruding portion 23 Stay 24 Thermistor 25 Power supply connector 30 Pressure roller 30a Core metal 30b Elastic layer 30c Release layer 50 Heater 50a Heating element pattern 50b Base material 50c Glass layer 50d Conductive pattern 50e Electrode portion 50f Electrode portion 50g Electrode portion 50h Insulating layer 100 Image forming apparatus N Transfer site P Recording medium

Japanese Patent Laid-Open No. 10-142976

Claims (10)

A substrate having thermal conductivity;
A heat generating part formed in a predetermined range in the longitudinal direction of the substrate;
An electrode unit that feeds power from outside through an electrical contact;
A heating part that has a conductor part that conducts the heating part and the electrode part, and heats the material to be heated;
The heating element characterized in that the base material has a thickness in at least a part of a non-heat generating area where the heat generating part is not formed in a longitudinal direction smaller than a thickness in a heat generating area where the heat generating part is formed. .   The heating body according to claim 1, wherein a thickness of the base material in the non-heat generating region is uniform in the non-heat generating region.   2. The heating body according to claim 1, wherein a thickness of the base material in the non-heat generation region is different in the non-heat generation region.   2. The heating body according to claim 1, wherein in the non-heat generating region of the base material, a thickness in a region where the electrode portion is formed is smaller than a thickness in a region where the conductor portion is formed. .   2. The heating body according to claim 1, wherein a thickness in the non-heat generation region on one end side in the longitudinal direction of the base material is different from a thickness in the non-heat generation region on the other end side.   The heating body according to any one of claims 1 to 5, wherein the substrate is made of a ceramic member or a metal member. The heating body according to any one of claims 1 to 6,
A fixing member as the material to be heated, the inner peripheral surface of which contacts and slides on the heating body;
And a pressure member that forms a fixing nip portion with the heating body via the fixing member.   The fixing device according to claim 7, wherein a surface of the heating body on which the heat generating portion is not formed slides in contact with an inner peripheral surface of the fixing member. A holding member for holding the heating body on the inner periphery of the fixing member;
The fixing device according to claim 7, wherein the holding member is in contact with a non-formation range of the heat generating portion in the heating body to hold the heating body.   An image forming apparatus comprising the fixing device according to claim 7.