JP2004185899A - Sheet-like heater, and fixing device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet-like heater capable of restraining abnormal heat generation of a resistance heating element, and of preventing separation between a board of the sheet-like heater and the resistance heating element based on the difference of their thermal expansion rates, and to provide a fixing device using the sheet-like heater. <P>SOLUTION: The resistance heating element 12 is formed into a folded pattern folded back in the vicinities of both ends of the board 11, and composed of linear pattern parts 12a and curved pattern parts 12b formed by curving the folded parts. Each pattern part 12a corresponds to paper passing width D, and each pattern part 12b is formed outside the passing width D. Since the pattern part 12b is formed into a pattern having a large width, and its heating value is set lower than that of the pattern part 12a to prevent occurrence of temperature irregularity, so that separation of the heating element 12 from the board 11 based on the difference of the thermal expansion rates can be prevented. Since the pattern parts 12b are formed outside the passing width D, a fixing process is not affected even if the heating values of those parts are small. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a sheet heater and a fixing device of an image forming apparatus using the same.
[0002]
[Prior art]
2. Description of the Related Art In an electrophotographic image forming apparatus such as a copier, a laser printer, a facsimile, or a multifunction peripheral called an MFC having these functions, an electrostatic latent image of an image formed on a photoconductor is developed with toner. After the image is transferred to a recording medium, the image is fixed by performing a fixing process using a fixing device, and the image is recorded.
[0003]
Conventionally, as a fixing device used in such an image forming apparatus, a heat roller type fixing device using a metal roller having a halogen lamp disposed as a heat source on its inner surface has been used.
[0004]
Halogen lamps once convert electric energy into light energy and then into heat energy, and therefore have low heat conversion efficiency. Therefore, a technique has been proposed in which a resistance heating element capable of directly converting electric energy to heat energy is formed on the outer periphery of a core of a heat roller (see Patent Document 1).
[0005]
Further, a semi-cylindrical heat plate in which a sheet-like heater is arranged on the inner surface of a non-rotating semi-cylindrical body has been proposed (see Patent Document 2). This is used in a fixing belt-type fixing device configured to heat a fixing belt wound around an outer peripheral surface of a semi-cylindrical heat plate. In this semi-cylindrical heat plate, the heat capacity of the heat plate can be reduced, so that energy can be saved.
[0006]
[Patent Document 1]
JP-A-07-140828.
[0007]
[Patent Document 2]
JP-A-2002-72735.
[0008]
[Problems to be solved by the invention]
However, in the conventional sheet heater as described above, the substrate, the insulating layer, and the resistance heating element that constitute the sheet heater are each made of different materials, and have different coefficients of thermal expansion. Stress occurs between the layers of the resistance heating element. In particular, in the curved pattern portion located at the end of the resistance heating element, since stress is generated inside the curved section, there is an inconvenience that the resistance heating element generates abnormal heat due to peeling between the substrate and the resistance heating element. May be.
[0009]
The present invention provides a sheet-like heater that does not cause separation between a substrate and a resistance heating element without using a special pressing member or the like, and a fixing device of an image forming apparatus using the sheet-like heater. The purpose is to provide.
[0010]
[Means for Solving the Problems]
The present invention solves the above-mentioned problems, and the invention of claim 1 is a sheet-like heater in which a resistance heating element composed of a pattern having a plurality of folded portions formed in a plane is fixedly arranged on a substrate. The heating element includes a plurality of linear pattern portions arranged in parallel, and a plurality of folded pattern portions connecting the linear pattern portions to adjacent linear pattern portions, and the width of the folded pattern portion is a linear pattern portion. A sheet-shaped heater characterized by being formed wider than the width of the portion.
[0011]
In the resistance heating element of the sheet heater, the length in the longitudinal direction of the plurality of linear pattern portions arranged in parallel corresponds to the width of the recording medium transport area of the fixing device, and The folded pattern portion is configured to be located outside the recording medium transport area of the fixing device.
[0012]
Further, in the resistance heating element, the width of the plurality of linear pattern portions arranged in parallel is preferably at least three times the interval between adjacent linear pattern portions.
[0013]
Furthermore, the resistance heating element can be formed such that the shape of the folded pattern portion is curved.
[0014]
According to a fifth aspect of the present invention, there is provided a substantially semi-cylindrical heat plate provided with the sheet-shaped heater defined in the first aspect, and a loop-shaped fixing belt wound around and movable between the heat plate and the fixing member. And a pressing member for pressing the fixing belt against the fixing member.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described. FIG. 1 is a front view of a sheet heater 10 according to the first embodiment, and FIG. 2 is an enlarged sectional view thereof. In FIG. 1, reference numeral 11 denotes a substrate of a sheet heater, and reference numeral 12 denotes a resistance heating element disposed on the substrate 11. The resistance heating element 12 is formed in a folded pattern that is folded near both ends of the substrate 11, and includes a linear pattern portion 12a and a curved pattern portion 12b in which the folded portion is curved. Note that terminal portions 13a and 13b are formed at the ends of the linear pattern portion 12a.
[0016]
As shown in an enlarged cross section in FIG. 2, the sheet-shaped heater 10 includes an insulating layer 16 disposed on a substrate 11 via an adhesive layer 15, and a straight line via an adhesive layer 17 thereon. A resistance heating element 12 composed of a shape pattern portion 12a and a curved pattern portion 12b is arranged. The substrate 11 is made of, for example, 0.5 mm thick aluminum (material symbol A5052), and the insulating layer 16 is made of 35 μm thick heat resistant synthetic resin polyimide (PI). The adhesive layers 15 and 17 are made of thermosetting synthetic resin polyimide (PI) having a thickness of 8 μm.
[0017]
As the resistance heating element 12, for example, a metal heating element made of stainless steel (material symbol: SUS304) having a thickness of 30 μm is used.
[0018]
When used in a fixing device as described later, the sheet-shaped heater 10 is used by being arranged on an inner surface of a substantially semi-cylindrical heat plate 50 formed in an arc-shaped cross section around which a fixing belt is wound. . At this time, the substrate 11 of the sheet heater 10 can also serve as the holding plate 51 of the heat plate 50.
[0019]
The relationship between the positions of the linear pattern portion 12a and the curved pattern portion 12b of the resistance heating element 12 and the position of the recording medium to be subjected to the fixing process will be described. The recording medium passes through a portion D shown as a sheet passing width in FIG. The linear pattern portion 12a is formed corresponding to the sheet passing width D, and the curved pattern portion 12b and the terminal portions 13a and 13b are formed outside the sheet passing width D.
[0020]
FIG. 3 is a diagram illustrating an example of the dimensions of the linear pattern portion 12a and the curved pattern portion 12b of the resistance heating element 12 of the sheet heater 10. Assuming that the width of the linear pattern portion 12a is W1, the width of the folded portion of the curved pattern portion 12b is W2, and the interval (non-heating portion) between two adjacent linear pattern portions 12a is W3, the linear pattern portion 12a is formed. The width W2 of the folded portion of the curved pattern portion 12b is larger than the width W1 (W1 <W2), and the width W1 of the linear pattern portion 12a is more than three times the interval (non-heat generating portion) W3 between the linear pattern portions 12a. (W1> 3 × W3).
[0021]
Since the curved pattern portion 12b, which is the folded portion of the resistance heating element 12, is formed in a wide pattern and is formed outside the paper passing width D, the amount of heat generated by the curved pattern portion 12b, which is the folded portion, can be reduced. Since the temperature unevenness is hardly generated, the resistance heating element 12 is hardly peeled off.
[0022]
Further, since the curved pattern portion 12b at the folded portion of the end portion of the resistance heating element 12 is formed outside the paper width D, even if the sheet heater 10 using the resistance heating element 12 is used for a fixing device, the curved section is formed. Even if the heat value of the pattern portion 12b is smaller than the heat value of the linear pattern portion 12a, no problem occurs in the fixing process.
[0023]
FIG. 4 is a front view of the sheet-shaped heater 10 according to the second embodiment. As in the case of the first embodiment, the resistance heating element 22 has a folded pattern folded near both ends of the substrate 11. It is formed of a linear pattern portion 22a and a rectangular folded pattern portion 22b.
[0024]
Terminal portions 23a and 23b are formed at the ends of the linear pattern portion 22a. The linear pattern portion 22a is formed corresponding to the paper passing width D, and the folded pattern portion 22b and the terminal portions 23a and 23b are formed. , Outside the sheet passing width D.
[0025]
FIG. 5 is a front view of the sheet-shaped heater 10 of the third embodiment. As in the case of the first embodiment, the resistance heating element 32 has a folded pattern folded near both ends of the substrate 11. It is formed of a linear pattern portion 32a and a curved pattern portion 32b of a folded portion.
[0026]
Terminal portions 33a and 33b are formed at the ends of the linear pattern portion 32a. The linear pattern portion 32a is formed corresponding to the paper passing width D, and the curved pattern portion 32b and the terminal portions 33a and 33b are formed. , Outside the sheet passing width D.
[0027]
In the third embodiment, the size of the curved pattern portion 32b of the folded portion is shorter in the sheet passing width direction than that of the first embodiment, and the sheet passing width is increased even when the same size substrate 11 is used. Can be taken.
[0028]
FIG. 6 is a front view of the sheet-shaped heater 10 according to the fourth embodiment. The sheet-shaped heater 10 includes two resistance heating elements 42 and 45. Unlike the third embodiment, it is configured as a bent maze-shaped linear pattern.
[0029]
The resistance heating element 42 does not have a folded portion near both ends of the substrate 11 and is composed of a linear pattern portion and a folded portion 42a having the same width as the linear pattern. 43a and 43b are formed.
[0030]
The resistance heating element 45 is formed in a folded pattern near both ends of the substrate 11 and includes a linear pattern part 45a and a bent pattern part 45b of a folded part. Terminal portions 46a and 46b are formed.
[0031]
The length of the linear pattern portion 45a of the resistance heating element 42 (including the folded portion 42a) and the resistance heating element 45 is formed corresponding to the sheet passing width D, and the terminal portions 43a and 43b, the bent pattern portion 45b, and the terminal The portions 46a and 46b are formed outside the sheet passing width D. Since the sheet heater 10 of the fourth embodiment includes the two resistance heating elements 42 and 45, the heating value can be adjusted in multiple stages by switching the resistance heating elements.
[0032]
Also in the sheet heaters 10 of the second to fourth embodiments described above, the curved pattern portion 22b which is a folded portion of the resistance heating element 22, the curved pattern portion 32b which is a folded portion of the resistance heating element 32, the resistance heating element Since the 45 bent pattern portions 45b are formed in a wide pattern and formed outside the paper passing width D, the heat generation amount in this portion can be reduced, and the temperature unevenness is less likely to occur. Peeling is less likely to occur.
[0033]
FIG. 7 is a diagram for explaining the relationship between the pattern width of the resistance heating element and the amount of heat generated. The horizontal axis indicates the pattern width and the vertical axis indicates the amount of heat generated. It can be seen that the heat value is substantially inversely proportional to the pattern width, and the heat value decreases as the pattern width increases.
[0034]
FIG. 8 is a perspective view of a heat plate 50 used as a heat source of a fixing device described later. The heat plate 50 is constituted by fixing and disposing the above-described sheet heater 10 on the inner surface of a substantially semi-cylindrical holding plate 51 having an arc-shaped cross section by an appropriate known means such as bonding.
[0035]
Further, the sheet heater 10 described above can be formed into a substantially semi-cylindrical heat plate 50 by forming an arc-shaped cross section by press working or the like. In this case, the substrate 11 of the sheet heater 10 also serves as the holding plate 51.
[0036]
FIG. 9 is a cross-sectional view illustrating the configuration of a first type fixing device 60, in which a fixing belt 52 is wound around a heat plate 50 and a fixing roller 53. A pressure roller 54 is disposed at a position facing the fixing roller 53 with a fixing belt 52 interposed therebetween.
[0037]
When the pressure roller 54 is rotated in the direction of arrow a by a drive mechanism (not shown), the fixing roller 53 also rotates in the direction of arrow a. The fixing belt 52 moves in frictional contact with the fixing roller 53 and the pressure roller 54. At this time, the fixing belt 52 moves in the direction of arrow a while sliding on the outer surface of the heat plate 50, and heat is transmitted from the heat plate 50 to be heated. The fixing process is performed by passing the recording medium P to be fixed through the nip N between the pressure roller 54 and the fixing belt 52.
[0038]
In the above configuration, the fixing roller 53 may be driven and rotated instead of the configuration in which the pressure roller 54 is driven and rotated.
[0039]
FIG. 10 is a cross-sectional view illustrating the configuration of a second type of fixing device 61. In the first type of fixing device 60 shown in FIG. 9, the fixing roller 53 is replaced with a fixing pad 55.
[0040]
When the pressure roller 54 is rotated in the direction of arrow a by a drive mechanism (not shown), the fixing belt 52 comes into frictional contact with the pressure roller 54 and moves together with the pressure roller 54. The fixing belt 52 moves in the direction of arrow a while sliding on the outer surfaces of the heat plate 50 and the fixing pad 55, and heat is transmitted from the heat plate 50 to the fixing belt 52 to be heated. The fixing process is performed by passing the recording medium P to be fixed through the nip N between the pressure roller 54 and the fixing belt 52.
[0041]
FIG. 11 is a cross-sectional view illustrating the configuration of a third type of fixing device 62. In the first type of fixing device 60 shown in FIG. 9, the pressing roller 54 is replaced with a pressing pad 56. .
[0042]
When the fixing roller 53 is rotated in the direction of arrow a by a driving mechanism (not shown), the fixing belt 52 comes into frictional contact with the fixing roller 53 and moves together with the fixing roller 53. The fixing belt 52 moves in the direction of arrow a while sliding on the outer surface of the heat plate 50, and heat is transmitted from the heat plate 50 to the fixing belt 52 and heated. The fixing process is performed by allowing the recording medium P to be fixed to pass through the nip portion N between the pressure pad 56 and the fixing belt 52.
[0043]
The embodiments of the plurality of sheet heaters and the plurality of fixing devices have been described above. However, the embodiments described above include the inventions described below.
[0044]
(1) A sheet-shaped heater according to claim 1, wherein a resistance heating element made of a thin metal plate is fixedly arranged on an insulating layer made of a synthetic resin material formed on a substrate. Heater.
[0045]
(2) In the sheet heater according to the first aspect, the width of the linear pattern portion of the resistance heating element is W1, the width of the folded portion of the curved pattern portion is W2, and the interval between adjacent linear pattern portions is W3. A sheet heater characterized by satisfying a relationship of W1 <W2 and satisfying a relationship of W1> 3 × W3.
[0046]
(3) The sheet-shaped heater according to claim 1 or 2, wherein the folded pattern portion is formed in a rectangular shape.
[0047]
(4) The sheet heater according to claim 1 or 2, further comprising a plurality of resistance heating elements.
[0048]
(5) The sheet-shaped heater according to claim 1 or 2, further comprising a resistance heating element having a bent maze-shaped linear pattern.
[0049]
(6) The fixing device according to claim 5, wherein the fixing member is a fixing roller or a fixing pad, and the pressing member is a pressing roller or a pressing pad.
[0050]
【The invention's effect】
As described above, in the sheet heater of the present invention, the folded portion at the end of the resistance heating element is formed wider than the linear portion of the resistance heating element and smaller than the heat generation amount of the linear portion. Of the sheet heater can be prevented from being separated between the substrate and the resistance heating element based on the difference in the coefficient of thermal expansion.
[0051]
In the sheet heater according to the present invention, since the folded portion at the end of the resistance heating element is formed outside the paper passing width of the fixing device, it can be used in the fixing device without any trouble in the fixing process even if the heat generation amount in this portion is small. can do.
[0052]
Further, the fixing device using the sheet heater of the present invention does not cause separation between the substrate of the sheet heater and the resistance heating element, and thus provides a fixing device that operates stably for a long period of time. Can be.
[Brief description of the drawings]
FIG. 1 is a front view of a sheet heater according to a first embodiment of the present invention.
FIG. 2 is an enlarged cross-sectional view of the sheet heater shown in FIG.
FIG. 3 is a diagram illustrating an example of dimensions of a linear pattern portion and a curved pattern portion of a resistance heating element of a sheet heater.
FIG. 4 is a front view of a sheet heater according to a second embodiment.
FIG. 5 is a front view of a sheet heater according to a third embodiment.
FIG. 6 is a front view of a sheet heater according to a fourth embodiment.
FIG. 7 is a view for explaining a relationship between a pattern width of a resistance heating element and a heat generation amount.
FIG. 8 is a perspective view of a heat plate using a sheet heater.
FIG. 9 is a cross-sectional view illustrating a configuration of a first type fixing device 60.
FIG. 10 is a cross-sectional view illustrating a configuration of a second type fixing device 61.
FIG. 11 is a cross-sectional view illustrating a configuration of a third type of fixing device 62.
[Explanation of symbols]
10 sheet heater 11 substrate (sheet heater substrate)
12, 22, 32, 42 Resistance heating elements 12a, 22a, 32a Linear pattern portions 12b, 32b Curved pattern portions 13a, 13b, 23a, 23b, 33a, 33b Terminal portions 15, 17 Adhesive layer 16 Insulating layer 22b Folded pattern Part 42a Folded parts 43a, 43b, 46a, 46a Terminal part 45 Resistance heating element 45a Linear pattern part 45b Bent pattern part 50 Heat plate 51 Holding plate 52 Fixing belt 53 Fixing roller 54 Pressure roller 55 Fixing pad 56 Pressure pad 60 First-type fixing device 61 Second-type fixing device 62 Third-type fixing device

Claims (5)

In a sheet heater in which a resistance heating element composed of a pattern having a plurality of folded portions formed in a plane is fixedly arranged on a substrate,
The resistance heating element includes a plurality of linear pattern portions arranged in parallel, and a plurality of folded pattern portions connecting the linear pattern portions to adjacent linear pattern portions, and the width of the folded pattern portion is linear. A sheet-shaped heater formed to be wider than the width of the shape pattern portion. In the resistance heating element, the length in the longitudinal direction of the plurality of linear pattern portions arranged in parallel corresponds to the width of the recording medium transport area of the fixing device, and the folded pattern portion of the resistance heating element is the fixing device. 2. The sheet-shaped heater according to claim 1, wherein the sheet-shaped heater is configured to be located outside the recording medium conveyance area. 3. The resistance heating element according to claim 1, wherein a width of a plurality of parallel linear pattern portions is at least three times a distance between adjacent linear pattern portions. 4. Sheet heater. The sheet heater according to claim 1 or 2, wherein the resistance heating element has a folded pattern formed in a curved shape. 2. A substantially semi-cylindrical heat plate provided with a sheet heater as defined in claim 1, a loop-shaped fixing belt wound around and movable between the heat plate and the fixing member, and fixing on the fixing member. A fixing device, comprising: a pressing member for pressing the belt.

Images