JP6172360B1 - Heating device, fixing device and image forming apparatus - Google Patents

Abstract

An object of the present invention is to smooth the temperature distribution in the longitudinal direction with a heating device or the like in which a resistance heating element is divided into a plurality of parts, and to shorten the rise time to a predetermined temperature. A heater to which the present invention is applied includes a substrate, planar heating elements 112, 113, 114 arranged along the longitudinal direction of the substrate, and the substrate of the planar heating elements 112, 113, 114. A plurality of power supply bodies 115 and 116 which are formed at both ends in the width direction along the longitudinal direction and which form power supply lines for the planar heat generation elements 112, 113 and 114, and are arranged in the longitudinal direction of the substrate and are adjacent to each other. The ends 112S, 113S, 114S of the bodies 112, 113, 114 facing each other have a narrower interval between the power supply lines than other intervals. [Selection] Figure 4

Description

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

In Patent Document 1, the resistance heating element is divided into three or more portions in the longitudinal direction in order to prevent the non-sheet-passing portion temperature rise, and a current is supplied to the divided resistance heating element in the conveying direction of the heated material. A heating device is disclosed in which power is supplied so that the current flows, and the divided resistance heating elements are electrically connected in series.
Further, in Patent Document 2, in order to suppress uneven heat generation distribution in the heater longitudinal direction due to a region that does not generate heat in the heater longitudinal direction in the parallelogram heating block of the divided circuit, it is provided on the heater substrate along the substrate longitudinal direction. A resistance heating element is electrically connected in parallel between the two conductive patterns, and the resistance is set so that the shortest current path of each resistance heating element overlaps the shortest current path of the adjacent resistance heating element in the longitudinal direction of the substrate. A heater for disposing a heating element is disclosed.

JP 2007-25474 A Japanese Patent No. 5518080

For example, in a heating device used in a fixing device that heats and fixes a toner image, the resistance heating element is divided into a plurality of parts for the purpose of reducing the total resistance of the resistance heating element or limiting the heating location. Technology has been proposed. If this resistance heating element is divided into multiple parts, slit-like non-heat-generating parts will occur in the divided parts, so if no measures are taken, heat will drop at the slit-like non-heat-generating parts. End up.
In order to prevent unevenness in heat generation in the longitudinal direction due to the drop in heat generation, there are techniques of, for example, forming the heat generation block into a parallelogram shape, or arranging the heat generation block, for example, at an angle. However, for example, if the heat generating block is simply formed in a parallelogram shape, it becomes difficult for a current to flow at an acute angle portion of the parallelogram shape, resulting in uneven heat generation distribution. In addition, when the rectangular heat generating blocks are arranged obliquely, the base material becomes larger due to the increased installation space, and the rise to a predetermined temperature is delayed.
An object of the present invention is to smooth the temperature distribution in the longitudinal direction with a heating device or the like in which a resistance heating element is divided into a plurality of parts, and to shorten the rise time up to a predetermined temperature.

The invention according to claim 1 is formed on a substrate, a resistance heating element arranged along a longitudinal direction of the substrate, and both ends of the resistance heating element in a width direction along the longitudinal direction of the substrate. A plurality of resistance heating elements arranged in the longitudinal direction of the substrate, and configured to increase the amount of heat generation at an end portion where the adjacent resistance heating elements face each other. The current path of the resistance heating element overlaps with the adjacent resistance heating element in the longitudinal direction, and the power supply line covers the periphery of the facing surface of the overlapping acute angle portion of the resistance heating element. It is comprised as follows. It is a heating apparatus characterized by the above-mentioned.
Invention according to claim 2, intervals of the power supply line, Ri a gradually narrowed toward the end portion in which the resistance heating element adjacent the facing, acute angle portions overlapping the parallelogram of the resistance heating element The heating device according to claim 1, wherein the tip of the heating device is cut .
According to a third aspect of the present invention, the resistance heating element is divided into a central portion and both end portions in the longitudinal direction of the substrate, and an interval between the feeding lines at both ends in the longitudinal direction of the central portion is smaller than other intervals. rather narrow Te, a heating apparatus according to claim 1 or 2 the tip of the acute angle portion is characterized in that it is cut to overlap parallelogram the resistance heating element.
The invention according to claim 4 is formed at both ends of the substrate, the plurality of resistance heating elements arranged along the longitudinal direction of the substrate, and the plurality of resistance heating elements along the longitudinal direction of the substrate. A conductor that forms a power supply line for the resistance heating element, and a conductor that is provided separately from the power supply line at an end portion where the plurality of resistance heating elements face each other, and the adjacent resistance heating element faces each other It is configured to increase the amount of heat generation at the part and to raise the temperature of the opposite end of the resistance heating element to be higher than the other part to compensate for the slit of the adjacent resistance heating element . It is the heating apparatus characterized by these.
The invention according to claim 5 is an insulator formed between the substrate and the resistance heating element, and a metal formed along the longitudinal direction of the substrate on one side of the insulator facing the substrate. The heating device according to any one of claims 1 to 4, further comprising a body.
According to a sixth aspect of the present invention, a fixing member that fixes a toner image on a recording material and a heating unit that heats the fixing member are provided. The heating unit includes a substrate and a longitudinal direction of the substrate. A resistance heating element that is arranged, and a conductor that is formed at both ends in the width direction along the longitudinal direction of the substrate of the resistance heating element to form a power supply line for the resistance heating element. A plurality of arranged in the longitudinal direction of the substrate and configured to increase the amount of heat generation at an end portion where the adjacent resistance heating elements face each other, and the current path of the resistance heating elements is The fixing device is configured to overlap in a longitudinal direction, and the power supply line is configured to cover a surface of an opposing acute angle portion of the resistance heating element facing each other .
According to a seventh aspect of the present invention, there is provided a toner image forming portion that forms a toner image, a transfer portion that transfers a toner image formed by the toner image forming portion to a recording material, and a transfer portion that transfers the toner image to the recording material. A fixing unit that fixes the toner image, and the fixing unit includes a fixing member that fixes the toner image on the recording material, and a heating unit that heats the fixing member. A resistance heating element arranged along the longitudinal direction of the substrate; and a conductor formed at both ends of the resistance heating element in the width direction along the longitudinal direction of the substrate to form a power supply line for the resistance heating element; A plurality of the resistance heating elements are arranged in the longitudinal direction of the substrate, and are configured to increase the amount of heat generation at an end portion where the adjacent resistance heating elements face each other. Matching the resistance heating element And overlap in the longitudinal direction Te, an image forming apparatus wherein the feed line is configured so as to cover the periphery of the opposed surfaces, sharp edges overlapping portions of the resistance heating element.

According to the first aspect of the present invention, it is possible to smooth the temperature distribution in the longitudinal direction and to shorten the rise time up to a predetermined temperature.
According to the second aspect of the invention, the temperature change can be smoothed at the end portions of the resistance heating element facing each other.
According to the invention of claim 3, when the resistance heating element in the central portion of the heating device is heated and the both end portions are not heated, the temperature drop at the end of the resistance heating element in the central portion is suppressed. it can.
According to invention of Claim 4, the heat_generation | fever peak in the width direction of the resistance heat generating body of a heating apparatus can be disperse | distributed.
According to invention of Claim 5, the fall of the temperature between the heat_generation | fever areas of a heating apparatus can be suppressed.
According to the sixth aspect of the present invention, it is possible to provide a fixing device in which the temperature distribution in the longitudinal direction is smoothed and the start-up time to a predetermined temperature is shortened.
According to the seventh aspect of the present invention, it is possible to provide an image forming apparatus in which the temperature distribution in the longitudinal direction is smoothed and the start-up time up to a predetermined temperature is shortened.

1 is a diagram illustrating a configuration of an image forming apparatus to which the exemplary embodiment is applied. 2 is a plan view for explaining the configuration of a fixing device to which the exemplary embodiment is applied. FIG. 2 is a cross-sectional view for explaining a configuration of a fixing device to which the exemplary embodiment is applied. FIG. It is a top view for demonstrating the heater to which this Embodiment is applied. (A), (b) is a figure for demonstrating the heater to which this Embodiment is applied. It is a figure for demonstrating distribution of the temperature of the heater to which this Embodiment is applied. (A)-(c) is a figure for demonstrating the modification of the heater to which this Embodiment is applied. (D)-(f) is a figure for demonstrating the modification of the heater to which this Embodiment is applied. It is a figure for demonstrating the modification of the heater to which this Embodiment is applied.

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
<Description of Image Forming Apparatus 1>
FIG. 1 is a diagram illustrating a configuration example of an image forming apparatus 1 to which the exemplary embodiment is applied. An image forming apparatus 1 shown in FIG. 1 is a so-called tandem color printer, and includes an image forming unit 10 that forms an image based on image data and a control unit 31 that controls the operation of the entire image forming apparatus 1. Further, for example, a communication unit 32 that receives image data by communicating with a personal computer (PC) 3 or an image reading device (scanner) 4, and a predetermined image for the image data received by the communication unit 32. An image processing unit 33 that performs processing is provided.

The image forming unit 10 includes four image forming units 11Y, 11M, 11C, and 11K (also collectively referred to as “image forming unit 11”) arranged in parallel at a predetermined interval. Each image forming unit 11 is charged by a photosensitive drum 12 that forms an electrostatic latent image and holds a toner image, a charger 13 that charges the surface of the photosensitive drum 12 at a predetermined potential, and a charger 13. An LED (Light Emitting Diode) print head 14 that exposes the photosensitive drum 12 based on image data for each color, a developing device 15 that develops an electrostatic latent image formed on the photosensitive drum 12, and a photosensitive drum after transfer. A drum cleaner 16 for cleaning the surface of the twelve is provided.
Each of the image forming units 11 is configured in substantially the same manner except for the toner stored in the developing device 15, and each forms a toner image of yellow (Y), magenta (M), cyan (C), and black (K). To do.

  The image forming unit 10 also receives the intermediate transfer belt 20 onto which the color toner images formed on the photosensitive drums 12 of the image forming units 11 are transferred, and the color toner images formed on the image forming units 11. A primary transfer roll 21 that sequentially transfers (primary transfer) to the intermediate transfer belt 20 is provided. Further, a secondary transfer roll 22 that collectively transfers (secondary transfer) each color toner image transferred and superimposed on the intermediate transfer belt 20 to a sheet P that is a recording material, and each color toner image that is secondarily transferred is a sheet P. A fixing unit 60 is provided for fixing on the top. The fixing unit 60 functions as an example of a fixing device or a fixing unit.

  In the image forming apparatus 1 according to the present embodiment, the image data from the PC 3 or the scanner 4 is received by the communication unit 32 under the operation control by the control unit 31, and the received image data is previously received by the image processing unit 33. Defined image processing is performed. Thereafter, the image data subjected to this image processing is sent to each image forming unit 11 as image data for each color under the operation control by the control unit 31, and the image forming unit 10 performs the image forming process. .

  In the image forming unit 11K that forms, for example, a black (K) toner image in the image forming process in the image forming unit 10, the photosensitive drum 12 is rotated in the direction of arrow A while being charged at a predetermined potential by the charger 13. The LED print head 14 scans and exposes the photosensitive drum 12 based on the K color image data that is charged and transmitted from the image processing unit 33, and forms an electrostatic latent image related to the K color image on the photosensitive drum 12. The K-color electrostatic latent image formed on the photosensitive drum 12 is developed by the developing device 15, and a K-color toner image is formed on the photosensitive drum 12. Similarly, yellow (Y), magenta (M), and cyan (C) toner images are formed in the image forming units 11Y, 11M, and 11C, respectively.

  Each color toner image formed on the photosensitive drum 12 of each image forming unit 11 in this way is sequentially electrostatically transferred (primary transfer) onto the intermediate transfer belt 20 that moves in the direction of arrow B by the primary transfer roll 21. A superimposed toner image in which the toner of each color is superimposed is formed on the intermediate transfer belt 20. The superimposed toner image on the intermediate transfer belt 20 is conveyed to a region (secondary transfer portion T) where the secondary transfer roll 22 is disposed as the intermediate transfer belt 20 moves. When the superimposed toner image is conveyed to the secondary transfer unit T, the paper P is supplied from the paper holding unit 40 to the secondary transfer unit T in accordance with the timing. The superimposed toner image is collectively electrostatically transferred (secondary transfer) onto the conveyed paper P by the transfer electric field formed by the secondary transfer roll 22 in the secondary transfer portion T.

Thereafter, the sheet P on which the superimposed toner image is electrostatically transferred is conveyed to the fixing unit 60. The toner image on the paper P conveyed to the fixing unit 60 receives heat and pressure and is fixed on the paper P. Then, the paper P on which the fixed image is formed is conveyed to a paper stacking unit 45 provided in the discharge unit of the image forming apparatus 1.
On the other hand, the toner (primary transfer residual toner) adhering to the photosensitive drum 12 after the primary transfer and the toner (secondary transfer residual toner) adhering to the intermediate transfer belt 20 after the secondary transfer are respectively drum cleaner 16. , And the belt cleaner 25.
In this way, the image forming process in the image forming apparatus 1 is repeatedly executed for the number of printed sheets.

<Description of Fixing Unit 60>
Next, the fixing unit 60 of this embodiment will be described.
First, the overall configuration of the fixing unit 60 will be described with reference to FIGS. FIG. 2 is a plan view for explaining the configuration of the fixing unit 60 to which the present embodiment is applied, and FIG. 3 is a view showing a III-III section of the fixing unit 60 shown in FIG.

2 and 3, the fixing unit 60 includes a heater unit 100, a fixing belt 61 as an example of a fixing member that fixes the toner image by being heated by the heater unit 100, and an outer periphery of the fixing belt 61. And a pressing pad 63 that is pressed from the pressing roll 62 via the fixing belt 61.
In the present embodiment, the rotation axis direction of the fixing belt 61 in the fixing unit 60 is the “longitudinal direction”. Further, since the sheet P is conveyed in the moving direction of the fixing belt 61 in the nip portion N, this moving direction is referred to as a “conveying direction”. Furthermore, the width direction of the heater 110 described later is simply referred to as “width direction”.

  The heater unit 100 is disposed on the inner peripheral side of the fixing belt 61 and heats the fixing belt 61 from the inner peripheral side. The heater unit 100 includes a heater 110 that is a heat generation source and a support portion 120. Although not shown, the support portion 120 supports the heater 110 at both ends in the longitudinal direction.

  The fixing belt 61 is composed of an endless belt member whose original shape is a cylindrical shape, and includes a base material layer that forms mechanical strength as a whole and a release layer that is coated on the base material layer. Have. This release layer is in direct contact with the unfixed toner image held on the paper P.

  In the pressure roll 62, for example, a heat-resistant elastic body layer is formed on the outer peripheral surface of a cylindrical cored bar, and a release layer made of heat-resistant resin coating or heat-resistant rubber coating is laminated. The pressure roll 62 is disposed in the entire region in the longitudinal direction in the region where the fixing belt 61 is pressed, and is rotated in the direction of arrow D in FIG. 3 following the fixing belt 61. The pressure roll 62 is pressed against the pressing pad 63 via the fixing belt 61 by using a pressing spring 68 (see FIG. 2).

  The pressing pad 63 is composed of a block-like rigid body such as silicone rubber or fluororubber. The pressing pad 63 is supported by the support unit 120 inside the fixing belt 61. As shown in FIG. 3, for example, a groove-shaped member having a U-shaped cross section faces the support portion 120 toward the pressure roll 62. The pressing pad 63 is pressed by the support portion 120 and pressed by the pressure roll 62 via the fixing belt 61.

  The pressure roll 62 and the pressing pad 63 form a nip portion N with the fixing belt 61 being sandwiched. By passing the paper P holding the unfixed toner image through the nip portion N, pressure is applied and the heat of the fixing belt 61 heated by the heater unit 100 is applied to fix the unfixed toner image on the paper P. To do.

<Description of heater 110>
Next, the structure of the heater 110 that functions as an example of a heating unit or a heating device will be described with reference to FIGS. FIG. 4 is a plan view for explaining the heater 110 to which the present embodiment is applied. 5A and 5B are explanatory views schematically showing the heater 110 to which the present embodiment is applied. FIG. 5A is a plan view and FIG. 5B is a cross-sectional view. . Further, FIG. 6 is a diagram for explaining the temperature distribution of the heater 110.

  The heater 110 to which this embodiment is applied is a strip-like member extending in the longitudinal direction and has flexibility. The heater 110 includes a substrate 111 and a plurality of resistance heating elements 112, 113, and 114 that are formed on the substrate 111 and generate heat when a voltage is applied. Further, power supply bodies 115 and 116 that supply voltage to the resistance heating elements 112, 113, and 114 and power supply electrodes 117 of the power supply bodies 115 and 116 are provided. The heating surface on which the resistance heating elements 112, 113, 114, the power feeding bodies 115, 116, and the electrode 117 are formed is protected by an overcoat layer 118. In the present embodiment, the heat generating surface of the heater 110 is arranged in a state of being bent in an arc shape along the inner peripheral surface where the nip portion N of the fixing belt 61 is not formed.

  The substrate 111 has heat resistance and insulating properties, and is made of, for example, a material having good thermal conductivity such as polyimide, ceramic such as alumina or aluminum nitride, or metal.

  The power feeding bodies 115 and 116 and the power feeding electrode 117 are simultaneously formed, for example, by screen printing of silver paste. The power feeders 115 and 116 are formed along the longitudinal direction in which the resistance heating elements 112, 113, and 114 are arranged side by side, that is, at both ends in the width direction along the longitudinal direction of the substrate 111, and extend along the longitudinal direction 2. A power supply line is formed. The power supply bodies 115 and 116 and the power supply electrode 117 are provided for the purpose of supplying a voltage to the resistance heating elements 112, 113, and 114. Therefore, the resistances of the power feeding bodies 115 and 116 and the power feeding electrode 117 are lower than the resistances of the resistance heating elements 112, 113, and 114.

  FIG. 5A schematically shows an arrangement structure on the substrate 111 of the power supply bodies 115 and 116 that are power supply lines and the power supply electrodes 117 that supply a voltage to the power supply bodies 115 and 116. . In the present embodiment, the resistance heating element extending in the longitudinal direction of the substrate 111 is divided to form a plurality of resistance heating elements 112, 113, 114, and the power supply bodies 115, 116 that are power supply lines are also divided. It is formed corresponding to the resistance heating elements 112, 113 and 114.

  The resistance heating elements 112, 113, and 114 are made of a conductive heating material, and are formed by screen printing using a paste prepared by kneading graphite, glass powder (inorganic binder), and an organic binder, for example. ing.

The overcoat layer 118 is made of a heat resistant material such as glass. The overcoat layer 118 covers the resistance heating elements 112, 113, 114 printed on the substrate 111 by covering the resistance heating elements 112, 113, 114, the power feeding bodies 115, 116, and the power feeding electrode 117 with a heat resistant material. In addition, electrical insulation on the surface of the heater 110 is ensured.
Further, the overcoat layer 118 is in contact with the inner peripheral surface of the fixing belt 61, and the heater 110 ensures slidability with the fixing belt 61 by the overcoat layer 118.

Next, detailed contents of the resistance heating elements 112, 113, and 114 to which the present embodiment is applied and the power feeding bodies 115 and 116 will be described with reference to FIG.
The resistance heating elements 112, 113, and 114 are arranged along the longitudinal direction. The resistance heating elements 112 and 114 are disposed at both ends in the longitudinal direction of the substrate 111 (hereinafter simply referred to as “both ends”), and the resistance heating element 113 is interposed between the resistance heating elements 112 and 114 (hereinafter referred to as “center portion”). And). The resistance heating element 112, 113, 114 is divided into a plurality of resistance heating elements extending in the longitudinal direction.

  A slit S1 is formed between the resistance heating element 112 and the resistance heating element 113 adjacent to the heater 110. In addition, a slit S2 is formed between the resistance heating element 113 and the resistance heating element 114. In the present embodiment, the slits S1, S2 have, for example, the same width in the longitudinal direction, and this width is, for example, 1 mm.

  Each of the resistance heating elements 112, 113, 114 has a rectangular shape extending in the longitudinal direction. In the present embodiment, each of the resistance heating elements 112, 113, and 114 has the same width in the width direction, and is about 30 mm, for example. In addition, the resistance heating elements 112 and 114 at both ends have the same length in the longitudinal direction, and the resistance heating element 113 disposed at the center is longer than the resistance heating elements 112 and 114. More specifically, the length of each of the resistance heating elements 112, 113, and 114 is determined according to, for example, the size of the sheet P being conveyed. For example, the resistance heating element 113 at the center is 210 mm in accordance with the A4 size, and the resistance heating elements 112 and 114 at both ends are transported by a sheet P having a width of 297 mm, which is the length of the A4 size. In consideration of the above, a width of about 42.5 mm can be obtained in consideration of 1 mm of the width of the slit. For example, when an A4 size short is used as the head in the conveyance direction (A4 vertical feeding) and an image is formed using the central portion in the longitudinal direction, the heater 110 is a resistance heating element 113 disposed in the central portion. Only an excessive temperature rise in a portion where the paper P is not conveyed is suppressed. On the other hand, for example, when forming an image using the central portion in the longitudinal direction with the A4 size long side as the head in the transport direction (A4 lateral feed), the heater 110 is connected to the resistance heating element 113 disposed in the central portion. The divided resistance heating elements 112 and 114 at both ends are heated. In this way, the heater 110 heats each of the resistance heating elements 112, 113, 114 alone or in combination according to the size of the paper P.

  The resistance heating element 112 has an end 112 </ b> S on the side facing the adjacent resistance heating element 113. Further, the resistance heating element 113 has end portions 113 </ b> S on both ends thereof, that is, on the side facing the adjacent resistance heating element 112 and the resistance heating element 114. Further, the resistance heating element 114 has an end 114S on the side where the adjacent resistance heating element 113 faces. The end 113S and the end 112S form a slit S1, and the end 113S and the end 114S form a slit S2.

  Here, in the present embodiment, as a characteristic configuration, notches C that are inclined surfaces inclined toward the center in the width direction are formed at both ends of the surface where the end 112S of the resistance heating element 112 is formed. Is formed. Similarly, notches C are formed at both ends of the surface where the end 113S of the resistance heating element 113 is formed, and notches C are formed at both ends of the surface where the end 114S of the resistance heating element 114 is formed. ing. Here, since two power supply lines 115 and 116, which are two power supply lines, are formed at both ends in the longitudinal direction where the resistance heating elements 112, 113, and 114 are formed, in this embodiment, this cutting is performed. Due to the notch C, the resistance heating elements 112, 113, 114 are spaced apart from each other at the ends of the adjacent resistance heating elements facing each other (end 113S and end 112S, and end 113S and end 114S). It will be narrower than the interval.

  Further, since the surface of the notch C is an inclined surface, the interval between the power supply lines formed by the power supply bodies 115 and 116 gradually increases toward the end portions 112S, 113S, and 114S where the adjacent resistance heating elements face each other. It will become narrower.

<About the heating action of the heater unit 100>
Next, a heat generating action in which the heater unit 100 is energized and the heater unit 100 generates heat will be described.
The heater 110 supplies power to the power supply bodies 115 and 116 via the power supply electrode 117 and heats the resistance heating elements 112, 113, and 114, thereby increasing the temperature over the entire length in the longitudinal direction. . In the image forming apparatus 1 shown in FIG. 1, when the temperature in the longitudinal direction of the heater 110 rises to a predetermined temperature and the rotation peripheral speed of the fixing belt 61 by the rotation of the pressure roll 62 becomes steady, the fixing is performed. The paper P is conveyed to the press nip N formed by the belt 61 and the pressure roll 62, and the unfixed toner image is fixed on the paper P.

この式（１）により、抵抗値Ｒが小さくなれば、発熱量は大きくなることが理解できる。 Here, the amount of heat generated by the heater 110 will be examined.
The resistance value R per unit length between the feeder lines formed by the feeders 115 and 116 is determined by the interval between the two feeder lines, and the resistance value R decreases as the interval between the feeder lines becomes narrower. There is. If the potential difference between the power supply lines is V and the potential difference supplied from the power supply electrode 117 is constant, the heat generation amount W per unit length in the longitudinal direction is expressed by the following equation.

From this equation (1), it can be understood that the heating value increases as the resistance value R decreases.

  Here, when the resistance heating element is divided and no measures are taken, temperature drop occurs in the divided slit region, and heat generation unevenness occurs. Also in the present embodiment, the slit S1 between the resistance heating element 112 and the resistance heating element 113 and the portion of the slit S2 between the resistance heating element 113 and the resistance heating element 114 do not generate heat. However, in the present embodiment, notches C are provided in the resistance heating elements 112, 113, 114 at the slits S1 and S2, and the interval between the power supply lines by the power supply bodies 115, 116 is narrowed. Due to the presence of the notch C, the interval between the power supply lines becomes narrow at the slits S1, S2 of the resistance heating elements 112, 113, 114. By reducing the interval between the power supply lines, the resistance value R per unit length decreases at the slits S1 and S2 of the resistance heating elements 112, 113, and 114. As a result of the decrease in the resistance value R, the amount of heat generated by the resistance heating elements 112, 113, 114 increases in the slits S1, S2, and the adjacent ends 112S, 113S, 114S of the resistance heating elements 112, 113, 114 are adjacent to each other. The calorific value increases. By increasing the heat generation amount of the end portions 112S, 113S, and 114S, the temperature drop caused by the slits S1 and S2 is complemented, and the heat generation unevenness is reduced.

Here, the width (length in the longitudinal direction) of the slits S1 and S2 is 1 mm, and the length in the longitudinal direction of the notch C is 2 mm. If there are cutouts C on both sides of the slits S1 and S2, the length of the two cutouts C is 2 mm × 2 = 4 mm. The width of the slits S1 and S2 (length in the longitudinal direction) and the cutout C The ratio to the length is 1 to 4.
At this time, the target temperature of heat generation by the resistance heating elements 112, 113, and 114 is set to 100% T. Since the amount of heat generated in the slits S1 and S2 is 0, if the region of the slits S1 and S2 is compensated to 100% T by the notch C having a length four times that of the slits S1 and S2, the notch The target temperature for the portion C is 125% T, and the heat generation amount W may be 125%.

  As shown in the equation (1), in order to increase the heat generation amount W, the resistance value R may be decreased. Therefore, in order to reduce the heat generation amount W to 125%, the resistance value R is increased by 0.8 times. do it. In the present embodiment, the notch C is provided to increase the resistance value R. However, if the interval between the feeder lines and the resistance value R are in a proportional relationship, the interval between the feeder lines is 0.8 times. What is necessary is just to determine the shape of the notch C so that it may do. For example, if the interval between the feeder lines formed by the feeders 115 and 116 is 30 mm, the interval between the feeder lines formed by the notches C is 30 mm × 0. .8 = 24 mm, and assuming that notches C are formed on both sides in the width direction, the depth of each notch C is about 3 mm.

  FIG. 6 shows the temperature distribution of the heater 110 to which the present embodiment is applied. At both ends of the slits S1 and S2, the temperature is raised by the notch C to compensate for the temperature drop of the slits S1 and S2, and as a whole, the target temperature is brought to 100% T, thereby reducing unevenness in heat generation.

<Modification of Heater 110>
Next, a modified example of the heater 110 to which the present exemplary embodiment is applied will be described with reference to FIGS. 7-1 (a) to (c), FIGS. 7-2 (d) to (f), and FIG. FIG. 7-1 (a) is an example shown in FIG. 4, and notches C are provided on both ends in the width direction at both ends of the resistance heating elements 112 and 113 facing each other that constitute the slit S1. ing. 7-1 (b), (c) and FIG. 7-2 (d) differ from FIG. 7-1 (a) in the position, number and shape of the notches C. FIG. 7-2 (e) is an example in which the amount of heat generation is increased by a structure instead of the notch C. FIG. Further, FIG. 7-2 (f) is an example in which the amount of heat generation is increased by configuring the power supply line to be covered around the opposing surfaces of the overlapping acute angle portions of the resistance heating element having a parallelogram shape. .
Here, for the sake of simplification, the portion configuring the slit S2 is not shown, but a similar configuration can be employed. FIG. 8 shows an example of the heater 110 in which a heat diffusion metal layer 131 is formed on a substrate 111 and an insulating layer 132 is further formed thereon, as compared with FIG.

  In the above description, a notch C as shown in FIG. 7-1 (a) is provided, and the interval between the feeding lines is made narrower than the other intervals at the end where the adjacent resistance heating elements 112 and 113 face each other. The amount of heat generated at the end of the resistance heating element adjacent to the slit portion was increased. However, a notch such as the notch C (which may have a different shape) is provided in an arbitrary portion of the resistance heating element, or the number of the notches is changed so that the interval between the power feeding body 115 and the power feeding body 116 in the width direction is changed. The amount of heat generated can be adjusted by reducing the resistance value at the end and decreasing the resistance value.

For example, as shown in FIG. 7B, notches C are not formed on both sides in the width direction of the end portion 112S of the resistance heating element 112, but on both sides in the width direction of the end portion 113S of the resistance heating element 113. The structure formed only in this may be sufficient.
Further, for example, as shown in FIG. 7C, the notch C is formed only at one end in the width direction of the end 113S of the resistance heating element 113 and not at the other end. You can also.
For example, as shown in FIG. 7-2 (d), notches having different shapes can be provided at the facing end portions 112S and 113S. For example, as shown in FIG. 7-2 (d), the end portion 112S may be formed with a chamfered cutout C1, and the end portion 113S may be formed with, for example, a rectangular cutout C2 instead of a chamfered shape.

Moreover, it is also possible to comprise so that the resistance value of the edge part which an adjacent resistance heating element faces may be lowered | hung with another method.
For example, as shown to FIG.7-2 (e), the other electric power feeder 119 is provided in the edge parts 112S and 113S which face each other. As a result, the resistance values of the end portions 112S and 113S of the resistance heating elements 112 and 113 facing each other can be made smaller than the resistance values of other regions, and the heat generation amount of the end portions 112S and 113S is increased. be able to. In addition, as a secondary effect, the heat generation peaks of the end portions 112S and 113S can be dispersed in the slit direction (direction orthogonal to the longitudinal direction). Note that the power feeder 119 illustrated in FIG. 7-2 (e) does not need to be connected to the electrode 117 illustrated in FIG. 4 or FIG.

  In addition, as described in the above-mentioned document, when the parallelogram is overlapped to supplement the temperature of the slit, it is difficult for current to flow at an acute angle location unless any countermeasure is taken. However, for example, as shown in FIG. 7-2 (f), the ends of the overlapping acute angle portions of the parallelogram-shaped resistance heating elements 112 and 113 are cut, and the feeding line 115b and the feeding line 116a are further heated by this resistance heating. The body 112 and 113 are configured to cover the C-faces facing each other at the acute angle portions. As a result, the shortage of current at the acute angle portion is resolved and the amount of heat generated at the end portion can be increased.

  In the example shown in FIG. 5B, the resistance heating elements 112, 113, 114 and the power feeding bodies 115, 116 are formed directly on the substrate 111. However, a metal body can be provided between the substrate 111 and the resistance heating elements 112, 113, and 114 to further suppress the temperature drop between the heat generation regions.

  Specifically, as shown in FIG. 8, in the heater 110, a heat diffusion metal layer 131 is formed on a substrate 111, and an insulating layer 132 is further formed thereon. On the insulating layer 132, the power feeding bodies 115 and 116, the power feeding electrode 117, the resistance heating elements 112, 113, and 114 are formed, and the overcoat layer 118 is further formed. The heat diffusion metal layer 131 preferably has a higher thermal conductivity than the insulating layer 132. For example, a single metal such as a stainless steel foil (SUS330), an alloy, or the like can be used. By adopting this heat diffusion metal layer 131, the heating effect of the resistance heating elements 112, 113, 114 is increased, and the temperature unevenness in the direction of the heating surface in the heater 110 can be suppressed.

  In the above-described embodiment, as shown in FIG. 3, in the heater unit 100 of the fixing unit 60, the heater 110 is provided on the side opposite to the nip portion N of the fixing belt 61. That is, the heat generating surface of the heater 110 is arranged along the inner peripheral surface on the inner peripheral surface where the nip portion N of the fixing belt 61 is not formed. However, the heat generating surface of the heater 110 may be arranged on the inner peripheral surface where the nip portion N of the fixing belt 61 is formed.

DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 10 ... Image forming part, 20 ... Intermediate transfer belt, 22 ... Secondary transfer roll, 40 ... Paper holding part, 60 ... Fixing unit, 61 ... Fixing belt, 62 ... Pressure roll, 100 ... Heater Unit, 110 ... heater, 111 ... substrate, 112, 113, 114 ... resistance heating element, 112S, 113S, 114S ... end, 115, 116, 119 ... power feeding body

Claims (7)

A substrate,
A resistance heating element arranged along the longitudinal direction of the substrate;
A conductor that is formed at both ends in the width direction along the longitudinal direction of the substrate of the resistance heating element and forms a power supply line for the resistance heating element;
A plurality of the resistance heating elements are arranged in the longitudinal direction of the substrate, and are configured to increase the amount of heat generation at an end portion where the adjacent resistance heating elements face each other ,
The current path of the resistance heating element overlaps with the adjacent resistance heating element in the longitudinal direction, and the power supply line covers the surrounding surfaces of the overlapping acute angle portions of the resistance heating element. heating apparatus according to claim <br/> that are configured. Spacing of the feed line, Ri a gradually narrowed toward the end portion in which the resistance heating element adjacent the facing, that the front end of the acute angle portion overlapping the parallelogram of the resistance heating element is cut The heating device according to claim 1, wherein The resistance heating element is divided into a longitudinally central portion and both end portions of said substrate, the spacing of the feed line in the longitudinal ends of the central portion rather narrow compared to the other intervals, parallelogram the The heating apparatus according to claim 1 or 2, wherein a tip of an acute angle portion where the resistance heating element overlaps is cut . A substrate,
A plurality of resistance heating elements arranged along the longitudinal direction of the substrate;
A conductor that is formed at both ends of the resistance heating element along the longitudinal direction of the substrate and forms a power supply line to the resistance heating element;
A conductor provided separately from the power supply line at an end portion where the plurality of resistance heating elements face each other;
A conductor provided separately from the power supply line at an end portion where the plurality of resistance heating elements face each other;
Increasing the amount of heat generation at the end portion where the adjacent resistance heating element faces, and raising the temperature of the opposite end portion of the resistance heating element higher than that of the other portion, so that the slit of the adjacent resistance heating element falls. It is comprised so that may be supplemented, The heating apparatus characterized by the above-mentioned .   An insulator formed between the substrate and the resistance heating element, and a metal body formed along the longitudinal direction of the substrate on one side of the insulator facing the substrate. The heating apparatus according to any one of claims 1 to 4. A fixing member for fixing a toner image on a recording material;
A heating section for heating the fixing member,
The heating unit is
A substrate, a resistance heating element arranged along the longitudinal direction of the substrate, and a conductive line formed at both ends of the resistance heating element in the width direction along the longitudinal direction of the substrate to form a power supply line for the resistance heating element A plurality of the resistance heating elements are arranged in the longitudinal direction of the substrate, and configured to increase the amount of heat generation at an end portion where the adjacent resistance heating elements face each other ,
The current path of the resistance heating element overlaps with the adjacent resistance heating element in the longitudinal direction, and the power supply line covers the surrounding surfaces of the overlapping acute angle portions of the resistance heating element. It is comprised in the fixing device characterized by the above-mentioned. A toner image forming unit for forming a toner image;
A transfer unit that transfers the toner image formed by the toner image forming unit to a recording material;
A fixing unit that fixes the toner image transferred to the recording material by the transfer unit,
The fixing unit is
A fixing member that fixes a toner image on a recording material, and a heating unit that heats the fixing member;
The heating unit is
A substrate, a resistance heating element arranged along the longitudinal direction of the substrate, and a conductive line formed at both ends of the resistance heating element in the width direction along the longitudinal direction of the substrate to form a power supply line for the resistance heating element A plurality of the resistance heating elements are arranged in the longitudinal direction of the substrate, and configured to increase the amount of heat generation at an end portion where the adjacent resistance heating elements face each other ,
The current path of the resistance heating element overlaps with the adjacent resistance heating element in the longitudinal direction, and the power supply line covers the surrounding surfaces of the overlapping acute angle portions of the resistance heating element. an image forming apparatus characterized by being configured to.

Images