JP2015230349A - Heater and image heating apparatus including heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that a heater having a substrate, and a heat generating part consisting of two conductor patterns provided on the substrate and having different longitudinal lengths, and a heat element provided between the two conductor patterns on the substrate may sometimes generate left/right temperature unevenness caused by the lengths of the two conductor patterns.SOLUTION: A first heat-generating part and a second heat-generating part, which are two heat generation parts consisting of a heat element provided on a substrate, with it sandwiched between two conductor patterns having different lengths, are aligned in a short-side direction of the substrate along the longitudinal direction of the substrate. A longitudinal end part of the longer-length conductor pattern of the first heat-generating part and an end part of the shorter-length conductor pattern of the second heat-generating part that is close to the end part of the first conductor pattern are electrically connected, where the first heat-generating part and the second heat-generating part are electrically serially connected.

Description

  The present invention relates to a heater provided in an image heating apparatus used in an image forming apparatus such as a copying machine or a laser beam printer.

  A fixing device using a film has been put into practical use as an image heating device used in an image forming apparatus such as a copying machine or a laser beam printer. This fixing device generally includes a cylindrical film, a heater that contacts the inner surface of the film, and a pressure roller that forms a nip portion together with the heater through the film. The recording material carrying the toner image at the nip is heated while being conveyed to fix the toner image on the recording material. Since this fixing device uses a film having a low heat capacity, it has excellent quick start performance.

  However, since this film has a low heat capacity, the fixing device tends to cause a problem of temperature rise in a non-sheet passing portion in which an area where the recording material does not pass is excessively heated when fixing a small size recording material. It has been known. Therefore, Patent Document 1 discloses the following heater as a heater for improving the temperature rise of the non-sheet passing portion. The heater is configured such that a heating resistor having a positive temperature coefficient (Positive Temperature Coefficient) is sandwiched between two conductor patterns provided along the longitudinal direction of the substrate, and is energized in the recording material conveyance direction. It is. Since this heater has an electrical resistance value that increases as the temperature rises, the electrical resistance value at a portion that has become high due to the temperature rise of the non-sheet passing portion is higher than that of the sheet passing portion. As a result, the amount of current to the non-sheet passing portion is smaller than that of the sheet passing portion, and the amount of heat generated in the non-sheet passing portion is reduced.

JP 2009-103881 A

  Incidentally, Cited Document 1 discloses a heater H3 (FIG. 15) that changes the heat generation distribution in the longitudinal direction by changing the width in the short direction of the heating resistor in the longitudinal direction. If the width and length of the two conductor patterns are the same as in this heater, the voltage drop amount in the longitudinal direction of the two conductor patterns when a voltage is applied between the electrical contact portions D3 and D5. Are almost equal, and the unevenness of the heat generation on the left and right sides of the heater is not a problem.

  However, if the width and length of the two conductor patterns sandwiching the heating resistor are different, if there is a difference in the voltage drop amount in the longitudinal direction of the two conductor patterns, unevenness in the heat generation amount on the left and right of the heater It has been found that there is a case where the image becomes defective.

  Therefore, the present invention suppresses unevenness in the amount of heat generation on the left and right sides in a heater having a heating resistor sandwiched between two conductor patterns with different longitudinal lengths provided along the longitudinal direction on the substrate. With the goal.

  A first preferred embodiment of the present invention includes an elongated substrate, a first conductive pattern and a second conductor pattern which are provided on the substrate in a lateral direction of the substrate and are long along the longitudinal direction of the substrate. Provided between the first conductor pattern and the second conductor pattern and electrically connected to the first conductor pattern and the second conductor pattern in the longitudinal direction. A first heat generating portion having a first heating resistor, a third conductor pattern provided on the substrate in a lateral direction of the substrate, and a third conductor pattern that is long along the longitudinal direction of the substrate 4 conductor patterns, provided between the third conductor pattern and the fourth conductor pattern, and electrically connected to the third conductor pattern and the fourth conductor pattern in the longitudinal direction. A second heating resistor, In the heater used in an image heating apparatus that heats a toner image formed on a recording material, the first heat generating section and a second heat generating section provided side by side in the lateral direction. In the range from one end to the other end of the one heating resistor in the longitudinal direction, the second conductor pattern has an electrical resistance value per unit length equal to that of the first conductor pattern and the length in the longitudinal direction. Is longer than the first conductor pattern, and in the range from one end to the other end in the longitudinal direction of the second heating resistor, the third conductor pattern has an electric resistance value per unit length. The end of the second conductor pattern in the longitudinal direction that is equal to the fourth conductor pattern and has a length in the longitudinal direction longer than that of the fourth conductor pattern and closer to one end in the longitudinal direction of the substrate Part and the fourth conductor The heater is characterized in that the end of the turn in the longitudinal direction is electrically connected, and the first heating element and the second heating element are electrically connected in series. .

  A second preferred embodiment of the present invention is an elongated substrate, a first conductor pattern which is provided on the substrate in a lateral direction of the substrate, and is long along the longitudinal direction of the substrate. Two conductor patterns, and provided between the first conductor pattern and the second conductor pattern, and electrically connected to the first conductor pattern and the second conductor pattern in the longitudinal direction. A first heat generating portion including the first heat generating resistor, and a third conductor pattern which is provided on the substrate in a lateral direction of the substrate and is long along the longitudinal direction of the substrate. And the fourth conductor pattern, and provided between the third conductor pattern and the fourth conductor pattern, and electrically connected to the third conductor pattern and the fourth conductor pattern in the longitudinal direction. A second heating resistor connected to A heater for use in an image heating apparatus that heats a toner image formed on a recording material, the first heat generating unit and a second heat generating unit provided side by side in the lateral direction. In the range from the one end to the other end in the longitudinal direction of the first heating resistor, the second conductor pattern has an electric resistance value per unit length equal to that of the first conductor pattern and in the longitudinal direction. In the range from one end to the other end in the longitudinal direction of the second heating resistor, the third conductor pattern has an electrical resistance value per unit length that is longer than the first conductor pattern. Is equal to the fourth conductor pattern and the length in the longitudinal direction is longer than that of the fourth conductor pattern, and the length of the first conductor pattern on the side close to one end of the substrate in the longitudinal direction is The end and the third The longitudinal end of the body pattern is electrically connected to the longitudinal end of the second conductive pattern on the side of the substrate close to the other longitudinal end of the substrate, and the fourth conductive pattern. The longitudinal end of the heater is electrically connected, and the first heating element and the second heating element are electrically connected in parallel.

  In a heater having a heating resistor sandwiched between two conductor patterns having different lengths in the longitudinal direction provided along the longitudinal direction on the substrate, unevenness in the amount of heat generated on the left and right can be suppressed.

1 is a schematic cross-sectional view of an image forming apparatus 10 according to a first embodiment. Schematic sectional view of the fixing device 12 in Embodiment 1. FIG. 3 is a schematic plan view of the fixing heater 16 in the first embodiment. Longitudinal potential distribution of each conductor and longitudinal heating distribution of the heating resistor in Example 1 Schematic plan view of the fixing heater 56 in the second embodiment. Longitudinal potential distribution of each conductor and longitudinal heating distribution of the heating resistor in Example 2 Schematic plan view of the fixing heater 67 in the third embodiment. Schematic configuration diagram of the heater drive circuit 21 in the third embodiment. Longitudinal heat generation distribution of the heating resistors 62, 63, 64 in Example 3 Modification of Example 3 Schematic plan view of fixing heaters 77, 87, 97 as other configuration examples in the present invention. Schematic plan view of fixing heaters 100 and 110 as other configuration examples in the present invention. Schematic plan view of the heater H1 in the comparative example Longitudinal potential distribution of each conductor in the comparative example and longitudinal heating distribution of the heating resistor Schematic plan view of a conventional heater

(Example 1)
The best mode for carrying out the present invention is illustratively described in detail below with reference to the drawings.

  However, the dimensions, materials, shapes, and relative positions of the components described in this embodiment should be changed as appropriate according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope of the invention to the following embodiments.

(1) Overall Configuration of Image Forming Apparatus The overall configuration of the image forming apparatus according to this embodiment will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing an overall configuration of a full-color laser beam printer 10 which is an example of an image forming apparatus. A cassette 11 is provided at the bottom of the printer 10 so that it can be inserted and removed. The recording material P is stacked and stored in the cassette 11. The recording material P is fed from the paper feeding cassette 11 by the pickup roller 13, separated one by one by the feed / retard roller pair 14, and fed to the registration roller 15. Is done. The printer 10 includes an image forming unit 7 corresponding to each color of yellow, magenta, cyan, and black. Below the image forming unit 7, scanner units 3YM and 3CK for irradiating a laser beam based on image information to form an electrostatic latent image on the photosensitive drum 1 are arranged. Each color image forming unit 7 includes a photosensitive drum 1, a charging unit 2 for charging the surface of the photosensitive drum 1, a developing unit 4 having a developing roller 5 for developing an electrostatic image on the photosensitive drum 1, and a primary transfer member. 8 and. The primary transfer member 8 forms a primary transfer portion together with the photosensitive drum 1 via the transfer belt 29, and transfers the toner image developed on the photosensitive drum 1 to the transfer belt 29. The toner image transferred to the transfer belt 29 in the primary transfer portion moves as the transfer belt 29 moves, and is transferred to the recording material P in the secondary transfer portion formed by the secondary transfer member 31 and the transfer belt 29. . Thereafter, the recording material onto which the toner image has been transferred passes through the fixing device 12 and is heated and pressurized to fix the toner image on the recording material P. Thereafter, the recording material is conveyed to the discharge roller pair 32 and discharged to the recording material stacking unit 33.

  Note that the possible width of the recording material P in the printer 10 in this embodiment is 76 mm to 216 mm in a direction orthogonal to the conveying direction (hereinafter referred to as the longitudinal direction), and the paper passing reference of the printer 10 is in the longitudinal direction. On the other hand, it is approximately the center (hereinafter referred to as the center reference).

  Although this embodiment deals with a color laser beam printer having a plurality of photosensitive drums, it can also be applied to a monochrome copying machine and printer having a single photosensitive drum.

(2) Fixing Device The fixing device 12 in this embodiment will be described with reference to FIG. The fixing device 12 of this embodiment is a fixing device using a low heat capacity film 20. The fixing device 12 includes a cylindrical film 20, a plate-like heater 16 that contacts the inner surface of the film 20, and a pressure roller 22 that forms a nip portion together with the heater 16 through the film 20.

  Each member of the fixing device 12 will be described. The film 20 is obtained by forming a rubber layer having a thickness of about 300 μm on a base layer such as SUS formed in a cylindrical shape having an inner diameter of 24 mm and a thickness of 30 μm. A PFA resin tube having a thickness of 30 μm is coated on the outside of the rubber layer as a surface layer. A heat-resistant resin such as polyimide may be used as the base layer material.

  Further, the rubber layer is not always necessary. A surface layer coated with a fluororesin such as PTFE may be used. The heater 16 is a member in which a heating resistor pattern is formed on an elongated substrate made of ceramic or the like. The detailed configuration of the heater 16 will be described later. The pressure roller 22 as a backup member is formed by forming a rubber layer of about 3 mm on a metal core and coating a PFA resin tube having a thickness of about 40 μm thereon. The outer diameter of the pressure roller 22 in this embodiment is 25 mm. As for this pressure roller 22, the edge part of the both sides of a metal core is supported between the side plate of the back side and the near side of the apparatus frame 24 which were not shown through the bearing. The support member 17 is formed of a liquid crystal polymer resin, and supports a surface on the side opposite to the surface that contacts the inner surface of the film 20 of the heater 16. The thermistor 18 is disposed so as to contact the inner surface of the film 20, and transmits temperature information of the film 20 to the heater drive circuit 21. The thermistor 19 is disposed at the center in the longitudinal direction of the surface of the heater 16 opposite to the surface that contacts the inner surface of the film 20, and transmits temperature information of the heater 16 to the heater drive circuit 21. The film 20, the heater 16, and the support member 17 constitute a film unit. By pressing this film unit against the pressure roller 22 in such a direction that the heater 16 faces the pressure roller 22, the heater 16 forms a nip portion N together with the pressure roller 22 via the film 20. The force for pressing the film unit against the pressure roller 22 is 98 N (10 kgf) on one side and 196 N (20 kgf) in total in the configuration of this embodiment. The entrance guide 23 is a member for guiding the recording material P that has passed through the secondary transfer nip to the nip portion N of the fixing device 12. The entrance guide 23 is made of polyphenylene sulfide (PPS) resin. The fixing paper discharge roller 26 is a member for conveying the fixed recording material to the paper discharge roller pair 32.

  A driving configuration of the fixing device 12 will be described. The pressure roller 22 is rotationally driven at a predetermined peripheral speed in the direction of the arrow by a driving member (not shown). The film 20 is driven and rotated by receiving a frictional force at the nip portion N by the rotational driving of the pressure roller 22.

  Next, control of the heater 16 will be described. Power supply to the heater 16 is controlled based on temperature information from the thermistor 18 or 19. Specifically, power supply to the heater 16 is controlled so that the temperature of the thermistor 18 or 19 becomes a target temperature at which fixing is possible.

  When the film 20 is driven and reaches a target temperature at which the heater 16 or the film 20 can be fixed by the control of the heater 16, the recording material P carrying the unfixed toner image T in the nip portion N is guided along the entrance guide 23. The The recording material P is heated while being conveyed in the nip portion N, and the unfixed toner image T is fixed on the recording material P. The recording material P that has passed through the nip N is separated from the film 20 and is discharged through the fixing paper discharge roller 26.

  The configuration of the heater 16 will be described in detail with reference to a schematic plan view of the heater 16 shown in FIG. The substrate 41 is a flat plate that is long in a direction orthogonal to the recording material conveyance direction, and is made of ceramic such as alumina or aluminum nitride. The substrate 41 of this example was 270 mm in the longitudinal direction, 15 mm in the lateral direction, and 1 mm in the thickness direction, and was made of alumina. The substrate is not limited to ceramic but may be formed of a metal such as SUS or a heat resistant resin such as polyimide.

  A heating resistor pattern 42 (first heating resistor) and 43 (second heating resistor) are formed on one surface of the substrate 41 by screen printing or the like along the longitudinal direction. The heating resistor pattern is formed of a material such as ruthenium oxide or silver palladium. A conductive paste (TCR = 1500 ppm / ° C.) having a positive temperature coefficient (Positive Temperature Coefficient, hereinafter referred to as PTC characteristic) is used as the heating resistor pattern. The heating resistor patterns 42 and 43 of the present embodiment are formed on the substrate with a thickness of about 10 μm, a width of about 1 to 5 mm, and a longitudinal length of 220 mm. The electrical resistance values in the short direction of the heating resistor patterns 42 and 43 of this embodiment are both 5Ω, and the total electrical resistance value when connected in series is set to 10Ω.

  The conductor patterns 42a (first conductor pattern) and 42b (second conductor pattern) are electrically connected to the heating resistor pattern 42 across the longitudinal direction of the substrate 41 with the heating resistor pattern 42 in between, and generate heat. A first heat generating portion is formed together with the resistor pattern 42. The conductor patterns 43b (third conductor pattern) and 43a (fourth conductor pattern) are electrically connected to the heating resistor pattern 43 across the longitudinal direction of the substrate 41 with the heating resistor pattern 43 in between, and generate heat. A second heat generating portion is formed together with the resistor pattern 43. These conductor patterns are formed of a material having a low electrical resistance value such as silver or silver palladium, and are formed on one surface of the substrate 41 by screen printing or the like along the longitudinal direction. In any of the conductor patterns, since the width in the short direction of the substrate 41 is 0.5 mm and the thickness is 10 μm, the electric resistance values per unit length are equal.

In this example, silver palladium of TCR = 1000 ppm / ° C. and resistance value per unit area = 9 × 10 ⁻³ Ω / mm ² is used as the material of the conductor pattern. The end in the longitudinal direction of the conductor pattern 42b and the end in the longitudinal direction of the conductor pattern 43a are electrically connected, and the first heat generating portion and the second heat generating portion are connected in series.

  The electrode pattern 44a (first electrical contact portion) and the electrode pattern 44b (second electrical contact portion) are electrically connected to the longitudinal end of the conductor pattern 42a and the longitudinal end of the conductor pattern 43b, respectively. It is connected. In addition, a thin glass coat 45 having a thickness of about 30 to 100 μm is formed in order to ensure the protection and insulation of the heating resistor patterns 42 and 43. The heating resistor patterns 42 and 43 are formed so that the width in the short direction gradually becomes narrower from the end to the center in the longitudinal direction. The connection length L42a of the conductor pattern 42a with the heating resistor and the connection length L42b of the conductor pattern 42b with the heating resistor have a relationship of L42a <L42b. In this embodiment, L42a = 220 mm and L42b = 222 mm are set. The power supply entrances A <b> 1 and B <b> 1 for the heating resistor pattern 42 are arranged to form a diagonal of the formation region of the heating resistor pattern 42. In the heating resistor pattern 43, conductor patterns 43a and 43b and an electrode pattern 44b are arranged so that the connection relationship between the conductor and the electrode in the heating resistor pattern 42 is opposite in the longitudinal direction. The connection length L43b of the conductor pattern 43b with the heating resistor 43 and the connection length L43a of the conductor pattern 43a with the heating resistor 43 have a relationship of L43a <L43b. In this embodiment, L43a = 220 mm and L42b = 222 mm are set. The power supply entrances A <b> 2 and B <b> 2 for the heating resistor pattern 43 are arranged to form a diagonal of the formation region of the heating resistor pattern 43. A power supply connector (not shown) is attached to the electrode patterns 44a and 44b of the fixing heater 16 in FIG. By supplying power from the heater drive circuit 21 to the electrode portions 44a and 44b through the power supply connector, a current flows in the transport direction (short direction of the heater 16) with respect to the heating resistor patterns 42 and 43. Heat is generated and the fixing heater 16 is heated.

  Next, FIG. 13 shows the configuration of the heater H1 of the comparative example, and the effect of the heater 16 of the present embodiment shown in FIG. 3 will be described in comparison with the comparative example.

  The heater H1 of the comparative example is provided between the two conductor patterns 1a and 1b provided along the longitudinal direction of the substrate and arranged in the short direction, and the conductor patterns 1a and 1b provided between the conductor patterns 1a and 1b. And a heating resistor pattern R1 electrically connected to 1b. The end of the conductor pattern 1a in the longitudinal direction is electrically connected to the electrode D1, and the end of the conductor pattern 1b in the longitudinal direction is electrically connected to the electrode E1. The connection length L1a of the conductor pattern 1a with the heating resistor pattern R1 and the connection length L1b of the conductor pattern 1b with the heating resistor pattern R1 have a relationship of L1a <L1b. FIG. 14A is a diagram showing the potential distribution in the longitudinal direction of the conductor pattern 1a and the conductor pattern 1b when the heater of FIG. 13 is energized. According to FIG. 14A, the voltage drop amount ΔV1a from the electrode D1 to the right end of the conductor pattern 1a and the voltage drop amount ΔV1b from the left end of the conductor pattern 1b to the electrode E1 have a relationship of ΔV1a <ΔV1b. ing. Accordingly, the potential differences ΔVL and ΔVR at both ends in the longitudinal direction of the conductor pattern 1a and the conductor pattern 1b are in a relationship of ΔVL <ΔVR. FIG. 14B shows a heat generation distribution when the heater of FIG. 13 is energized. When there is a difference between the potential differences ΔVL and ΔVR, the amount of heat generated when the heating resistor pattern R1 is energized can also be different. Therefore, in principle, there is a left-right difference in the heat generation amount of the heater, and the relationship of WL <WR is established between the heat generation amount WL on the left end side and the heat generation amount WR on the right end side in FIG.

  On the other hand, FIG. 4A shows the potential distribution in the longitudinal direction of the conductor patterns 42a, 42b, 43a, 43b in the present embodiment. According to FIG. 4 (a), the left-right difference in the voltage drop amount of the heating resistor pattern 42 obtained from the potential distribution of the conductor patterns 42a and 42b is obtained from the heating resistor pattern 43 obtained from the potential distribution of the conductor patterns 43a and 43b. It can be seen that the voltage drop amount cancels out due to the left-right difference. FIG. 4B shows an image of contribution to the heat generation distribution in the longitudinal direction of the heater 16 and the heat generation resistor patterns 42 and 43 in the present embodiment.

  The heat generation distribution in the longitudinal direction of the heater 16 shown here is that when 800 W of electric power is applied to the heater 16 and the maximum value of the heater surface temperature reaches 200 ° C. According to FIG. 4B, it can be seen that the left-right difference in the amount of heat generated between the heating resistor pattern 42 and the heating resistor pattern 43 is offset, and the left-right difference in the amount of heat generation is suppressed as a whole heater.

  In other words, according to the present embodiment, the left and right heat generation amount generated by the configuration of the heater H1 of the comparative example is configured so as to cancel out by the two heat generating portions arranged in the short direction. The unevenness of the calorific value can be suppressed.

  In the present embodiment, the case where the material of each conductor pattern and the width in the short direction are all the same and only the length is different has been described. However, the configuration of the present invention is not limited to the configuration of the present embodiment. The present invention can also be applied when the material and width of the conductor pattern are different. For example, a heat generating portion having two conductive patterns having the same length in the longitudinal direction of the substrate and different electrical resistance values from one end to the other end, and a heating resistor pattern sandwiched and connected between the two conductive patterns It is applicable also to the heater which has two by arranging in short direction. The configuration in which the difference in the electrical resistance value in the longitudinal direction of the conductor pattern, such as the configuration in which the materials and widths of the two conductor patterns sandwiching the heating resistor pattern are different, is the amount of heat generated by one heating resistor. The left-right difference increases. Therefore, it is effective to apply the technical idea of this embodiment. In this embodiment, the heater used in the fixing device has been described. However, a heater used in an image heating device that heats an image to increase the gloss of the image may be used.

(Example 2)
The heater in the present embodiment is obtained by connecting two heating resistor patterns 52 and 53 in parallel, and the description of the same configuration as in the first embodiment is omitted.

  FIG. 5 shows a plan view of the heater 56 in the present embodiment. The heating resistor pattern, the conductor pattern, and the electrode pattern of the heater 56 in the present embodiment are formed of the same material as in the first embodiment. The two heating resistor patterns 52 (first heating resistor) and 53 (second heating resistor) formed in the longitudinal direction of the substrate 51 have a width in the short direction gradually narrowing from both longitudinal ends to the center. It has become. The heating resistor pattern 52 is electrically connected between the conductor pattern 52a (first conductor pattern) and the conductor pattern 52b (second conductor pattern) to form a first heating portion. . The heating resistor pattern 53 is electrically connected to the conductor pattern 53b (third conductor pattern) and the conductor pattern 53a (fourth conductor pattern) to form a second heating portion. .

  The electrode pattern 54 a formed on one end of the substrate 51 includes an end portion in the longitudinal direction of the conductor pattern 52 a connected to the heating resistor pattern 52 and an end portion of the conductor pattern 53 b connected to the heating resistor pattern 53. And are electrically connected. The electrode pattern 54b formed on the other end of the substrate 51 is electrically connected to a conductor pattern 52b connected to the heating resistor pattern 52 and a conductor pattern 53a connected to the heating resistor pattern 53. It is connected. That is, the first heat generating part and the second heat generating part are connected in parallel. The combined electric resistance value of the heating resistor pattern 52 and the heating resistor pattern 53 is set to 10Ω. When a voltage is applied between the electrode patterns 54a and 54b, the heat generating resistor patterns 52 and 53 form a heat generation distribution in which the heat generation amount in the central portion is larger than the end portions in the longitudinal direction.

  Here, the connection length L52a of the conductor pattern 52a with the heating resistor pattern 52 and the connection length L52b of the conductor pattern 52b with the heating resistor pattern 52 have a relationship of L52a <L52b. In this embodiment, L52a = 220 mm and L52b = 222 mm are set. The power supply entrances A3 and B3 for the heating resistor pattern 52 are arranged so as to form a diagonal of the region where the heating resistor pattern 52 is formed. The connection length L53a of the conductor pattern 53a to the heating resistor pattern 53 and the connection length L53b of the conductor pattern 53b to the heating resistor pattern 53 have a relationship of L53a <L53b. In this embodiment, L53a = 220 mm and L53b = 222 mm are set. The power supply entrances A4 and B4 for the heating resistor pattern 53 are arranged so as to form a diagonal of the region where the heating resistor pattern 53 is formed.

  FIG. 6A is a diagram showing the potential distribution in the longitudinal direction of the conductor patterns 52a, 52b, 53a, 53b in the present embodiment. According to FIG. 6A, the left-right difference of the voltage drop amount of the heating resistor pattern 52 obtained from the potential distribution of the conductor patterns 52a and 52b is represented by the difference in the heating resistor pattern 53 obtained from the potential distribution of the conductor patterns 53a and 53b. It can be seen that the voltage drop is offset by the difference between the left and right. FIG. 6B shows a heat generation distribution in the longitudinal direction of the heater 56 in this embodiment and an image of contribution to the heat generation distribution of each of the heating resistor patterns 52 and 53. According to FIG. 6B, it can be seen that the left-right difference between the heat generation amounts of the heating resistor pattern 52 and the heating resistor pattern 53 is offset, and the left-right difference in the heat generation amount as a whole is suppressed.

  As described above, according to the present embodiment, even in a heater having a configuration in which a plurality of heat generating portions energized in the transport direction are connected in parallel, unevenness in the amount of heat generated on the left and right of the heater can be suppressed.

(Example 3)
The heater of the present embodiment is a heater having a configuration capable of independently controlling a plurality of heating resistor patterns. The description of the same configuration as that of the second embodiment is omitted.

  FIG. 7 shows a plan view of the heater 67 in this embodiment. The heating resistor pattern, the conductor pattern, and the electrode pattern in the heater 67 in the present embodiment are all formed of the same material as in the first embodiment. The heater 67 has two heat generating resistor patterns 62 (first ones) in which the heat generation amount in the central portion is made larger than that in the end portions by gradually decreasing the width in the short direction from the end portion in the longitudinal direction to the central portion. 1 heating resistance pattern) and 63 (second heating resistance pattern). The heater 67 further has a heating resistor pattern 64 (third) in which the heat generation amount at the end portion is larger than that at the center portion by gradually increasing the width in the short direction from the end portion in the longitudinal direction to the center portion. Heat generating resistor). The heating resistor pattern 62 is electrically connected between the conductor pattern 62a (first conductor pattern) and the conductor pattern 62b (second conductor pattern) to form a first heating portion. . The heating resistor pattern 63 is electrically connected between the conductor pattern 63b (third conductor pattern) and the conductor pattern 63a (fourth conductor pattern) to form a second heating portion. . Furthermore, the conductive pattern 64a (fifth conductive pattern) and the conductive pattern 64b (sixth conductive pattern) are sandwiched between the first heat generating part and the second heat generating part in the short direction of the substrate 61. A heating resistor pattern 64 electrically connected to them is provided. The electrode pattern 66a formed on one end of the substrate 61 is connected to the end in the longitudinal direction of the conductor pattern 62a and the end in the longitudinal direction of the conductor pattern 63b. A conductor pattern 64a connected to the heating resistor pattern 64 is connected to the electrode pattern 66b formed at the end of the substrate 61 on the same side as the electrode pattern 66a. The electrode pattern 66c formed on the other end side of the substrate 61 includes an end portion of the conductor pattern 62b on the other end side of the substrate 61, an end portion of the conductor pattern 63a, and an end portion of the conductor pattern 64b. Electrically connected. That is, the heating resistor pattern 62 and the heating resistor pattern 63 are connected in parallel between the electrode patterns 66a and 66c, and the heating resistor pattern 64 is connected between the electrode patterns 66b and 66c. The electrical resistance value in the short direction in each heating resistor pattern is set to 30Ω, the combined resistance value of the electrical resistance values in the short direction of the heating resistor patterns 62 and 63 is set to 15Ω, and the heating resistor pattern The electrical resistance value of 64 in the short direction is set to 15Ω.

  Here, the connection length L62a of the conductor pattern 62a to the heating resistor pattern 62 and the connection length L62b of the conductor pattern 62b to the heating resistor pattern 62 have a relationship of L62a <L62b. In this embodiment, L62a = 220 mm and L62b = 223 mm are set. The power supply entrances A5 and B5 with respect to the heating resistor pattern 62 are arranged to form a diagonal of the region where the heating resistor pattern 62 is formed.

  The connection length L63a of the conductor pattern 63a to the heating resistor pattern 63 and the connection length L63b of the conductor pattern 63b to the heating resistor pattern 63 have a relationship of L63a <L63b. In this embodiment, L63a = 220 mm and L63b = 223 mm are set. The power supply entrances A6 and B6 for the heating resistor pattern 63 are arranged so as to form a diagonal of the region where the heating resistor pattern 63 is formed.

  Furthermore, the connection length L64a between the conductor pattern 64a and the heating resistor pattern 64 and the connection length L64b between the conductor pattern 64b and the heating resistor pattern 64 have a relationship of L64a = L64b. In this embodiment, L64a = L64b = 221 mm is set. The power supply entrances A <b> 7 and B <b> 7 for the heating resistor pattern 64 are arranged to form a diagonal of the formation region of the heating resistor pattern 64.

  The drive control of the heater 67 in the present embodiment will be described with reference to FIG. The drive circuit 21 in FIG. 8 is a schematic example of a drive circuit that controls power control of the heater 67. When the temperature information of the thermistor 18 is input to the CPU 211, the CPU 211 controls the lighting timing of the triacs 212 a and 212 b to perform desired power control based on the detection result of the thermistor 18. Here, the triac 212a is connected to the heating resistor patterns 62 and 63 via the electrode pattern 66a, and the triac 212b is connected to the heating resistor pattern 64 via the electrode pattern 66b. The heating resistor patterns 62, 63 and 64 are connected to the electrode pattern 66c to form a circuit.

  The CPU 211 can independently control the lighting duty of the triac 212a and the lighting duty of the triac 212b, and can form a desired heat generation distribution in the longitudinal direction of the heater. For example, the CPU 211 determines the lighting duty ratio (hereinafter referred to as the lighting ratio) Pa: Pb of the triacs 212a and 212b and controls the driving so that the heat generation distribution in the longitudinal direction of the heater 67 has an arbitrary gradient. It becomes possible. In the case of this embodiment, for example, the heat generation distribution in the longitudinal direction when the lighting ratio Pa: Pb = 10: 10 is substantially flat, and the heat generation distribution when Pb / Pa <1, such as Pa: Pb = 10: 7, is the central portion. The heat generation distribution when Pb / Pa> 1, such as high, Pa: Pb = 7: 10, is the edge height.

  FIG. 9 also shows an image of contribution to the heat generation distribution in the longitudinal direction of the heater 67 and each heat generation resistor pattern 62, 63, 64 in the present embodiment. As in the second embodiment, the heating resistor patterns 62 and 63 are configured such that the left and right differences in the amount of heat generated by the heater 67 can be offset from each other. The heating resistor pattern 64 is configured so that the connection length between the conductor patterns 64a and 64b is the same, so that a difference in the amount of generated heat hardly occurs. By adopting such a configuration, it is possible to suppress unevenness in the amount of heat generated on the left and right sides of the heater as a whole.

  As described above, according to the present embodiment, even in a heater configuration having a plurality of heating resistors that can be independently driven and controlled, it is possible to suppress the left-right difference in the amount of heat generation in the longitudinal direction of the heater.

  FIG. 10 shows a schematic plan view of a heater 120 according to a modification of the present embodiment. The heater 120 is a heater capable of independently driving and controlling the heating resistor pattern 122 (first heating resistor) and the heating resistor pattern 123 (second heating resistor). The heating resistor pattern 122 is a heating resistor whose width in the short direction gradually decreases from the end portion in the longitudinal direction to the center portion, and the heating resistor pattern 123 has the width in the short direction in the end portion in the longitudinal direction. It is a heating resistor that gradually increases from the center to the center. The heating resistor pattern 122 and the heating resistor pattern 123 have an asymmetric shape with respect to a central line that divides the substrate 121 into two in the short direction.

  The heating resistor pattern 122 is provided between the conductor pattern 122a (first conductor pattern) and the conductor pattern 122b (second conductor pattern), and is electrically connected to the first heating part. Form. The heating resistor pattern 122 is also provided between the conductor pattern 123b (third conductor pattern) and the conductor pattern 123a (fourth conductor pattern), and is electrically connected to the second heating pattern. Forming part. The connection length of the conductor pattern 122b with the heating resistor pattern 122 is longer than the connection length of the conductor pattern 122a with the heating resistor pattern 122. Further, the connection length of the conductor pattern 123b with the heating resistor pattern 122 is longer than the connection length of the conductor pattern 123a with the heating resistor pattern 122. A longitudinal end portion of the conductive pattern 122a is connected to the electrode pattern 124a provided at one longitudinal end of the substrate 121. An electrode pattern 124b is provided at the end of the substrate 121 on the side where the electrode pattern 124a is provided, to which the end of the conductive pattern 123b in the longitudinal direction is electrically connected. The electrode pattern 124c provided at the other end in the longitudinal direction of the substrate 121 is electrically connected to the longitudinal end of the conductive pattern 122b and the longitudinal end of the conductive pattern 123a. .

  By changing the energization ratio to the heating resistor pattern 122 and the heating resistor pattern 123, the heat generation distribution in the longitudinal direction of the heater 120 can be made variable.

  In the heater having two heating resistor patterns that can be independently driven and controlled and are asymmetric in the short direction, the amount of heat generated on the left and right sides of the heater as a whole can be increased by adopting the configuration described above. Can be compensated for.

  In this embodiment, the conductor pattern 122a and the conductor pattern 123a are made the same length, and the conductor patterns 122b and 123b are made the same length, thereby further suppressing the left-right difference in the calorific value.

  As another structural example of the heater in this embodiment, the present invention can be applied to a heater having more than three heating resistor patterns. For example, a heater 77 (FIG. 11A) in which the width of the heating resistor pattern is gradually increased from the end portion to the center portion in the longitudinal direction, and a heater having a heating resistor pattern in which the width is locally changed in the longitudinal direction. 87 (FIG. 11B) may be used. Further, a heater 97 (FIG. 11C) of a ladder shape in which a large number of heating resistor patterns extending in the short direction of the substrate are sandwiched between conductor patterns may be used. Further, the present invention can also be implemented by the heater 100 (FIG. 12A) in which the heating resistor pattern and the conductor pattern are connected so as to cancel the left-right difference between the one surface side and the opposite surface side of the substrate. Furthermore, the present invention can also be implemented with the heater 110 (FIG. 12B) in which the heating resistor pattern and the conductor pattern are connected so as to cancel the left-right difference between the one surface side and the opposite surface side of the substrate. Further, the arrangement is not limited to being symmetric in the short direction of the substrate, but may be an asymmetric arrangement.

DESCRIPTION OF SYMBOLS 12 Fixing device 16 Heater 20 Film 22 Pressure roller 41 Substrate 42 Heating resistor pattern 42a, 42b Conductor pattern 43 Heating resistor pattern 43a, 43b Conductor pattern 61 Substrate 62 Heating resistor pattern 62a, 62b Conductor pattern 63 Heating resistor pattern 63a, 63b Conductor pattern 64 Heating resistor pattern 64a, 64b Conductor pattern 122 Heating resistor pattern 122a, 122b Conductor pattern 123 Heating resistor pattern 123a, 123b Conductor pattern

Claims (9)

An elongated substrate;
A first conductor pattern and a second conductor pattern which are provided on the substrate in a line in the short direction of the substrate and are long along the longitudinal direction of the substrate, and the first conductor pattern and the second conductor. A first heat generating portion provided between the first conductive pattern and a first heat generating resistor electrically connected to the first conductive pattern and the second conductive pattern in the longitudinal direction; ,
A third conductor pattern and a fourth conductor pattern which are provided on the substrate side by side in the short direction of the substrate and are long along the longitudinal direction of the substrate, and the third conductor pattern and the fourth conductor. A second heating resistor provided between the first conductor pattern and electrically connected to the third conductor pattern and the fourth conductor pattern in the longitudinal direction. A second heat generating portion provided side by side with the heat generating portion in the lateral direction;
In a heater used in an image heating apparatus for heating a toner image formed on a recording material,
In the range from one end to the other end in the longitudinal direction of the first heating resistor, the second conductor pattern has an electric resistance value per unit length equal to that of the first conductor pattern and the longitudinal direction. Is longer than the first conductor pattern, and in the range from one end to the other end in the longitudinal direction of the second heating resistor, the third conductor pattern has an electric resistance per unit length. The value is equal to the fourth conductor pattern and the length in the longitudinal direction is longer than the fourth conductor pattern,
The longitudinal end of the second conductor pattern on the side of the substrate close to the longitudinal end is electrically connected to the longitudinal end of the fourth conductor pattern, and the first The heat generating part and the second heat generating part are electrically connected in series. An elongated substrate;
A first conductor pattern and a second conductor pattern which are provided on the substrate in a short-side direction of the substrate and are long along the longitudinal direction of the substrate, the first conductor pattern and the second conductor pattern A first heat generating portion provided between the first conductive pattern and the first conductive pattern and electrically connected to the first conductive pattern and the second conductive pattern in the longitudinal direction. When,
A third conductor pattern and a fourth conductor pattern that are provided on the substrate in a lateral direction of the substrate and are long along the longitudinal direction of the substrate, the third conductor pattern, and the fourth conductor pattern. A second heating resistor provided between the conductor pattern and electrically connected to the third conductor pattern and the fourth conductor pattern in the longitudinal direction. A second heat generating portion provided side by side in the short direction,
In a heater used in an image heating apparatus for heating a toner image formed on a recording material,
In the range from one end to the other end in the longitudinal direction of the first heating resistor, the second conductor pattern has an electric resistance value per unit length equal to that of the first conductor pattern and the longitudinal direction. Is longer than the first conductor pattern,
In the range from one end to the other end in the longitudinal direction of the second heating resistor, the third conductor pattern has an electric resistance value per unit length equal to that of the fourth conductor pattern and the longitudinal direction. Is longer than the fourth conductor pattern,
The end in the longitudinal direction of the first conductor pattern on the side close to one end in the longitudinal direction of the substrate is electrically connected to the end in the longitudinal direction of the third conductor pattern, and The longitudinal end of the second conductor pattern on the side close to the other end in the longitudinal direction is electrically connected to the longitudinal end of the fourth conductor pattern, and the first heat generation is performed. And the second heat generating portion are electrically connected in parallel.   3. The heater according to claim 1, wherein the width of the first heating resistor in the short direction is larger at an end portion than at a center portion in the longitudinal direction.   4. The heater according to claim 3, wherein a width of the second heat generating resistor in the short direction is larger in a center portion than in an end portion in the longitudinal direction. The first heating resistor and the second heating resistor are equal in length in the longitudinal direction, and in the range from one end to the other end in the longitudinal direction of the first heating resistor,
The first conductor pattern has the same electrical resistance value per unit length and the length in the longitudinal direction as the fourth conductor pattern,
The said 2nd conductor pattern is equal to the said 3rd conductor pattern, and the electrical resistance value per unit length and the length of the said longitudinal direction are equal, The length of any one of Claims 1-4 characterized by the above-mentioned. heater. A fifth conductor pattern and a long first conductor pattern provided along the longitudinal direction of the substrate are provided side by side between the first heat generating portion and the second heat generating portion in the short direction of the substrate. 6 conductor pattern, provided between the fifth conductor pattern and the sixth conductor pattern, and electrically connected to the fifth conductor pattern and the sixth conductor pattern in the longitudinal direction. And a third heat generating resistor having a third heat generating resistor,
In the range from the one end to the other end in the longitudinal direction of the third heating resistor, the fifth conductor pattern includes the sixth conductor pattern, the electrical resistance value per unit length, and the length in the longitudinal direction. Are equal,
The longitudinal end of the sixth conductor pattern is electrically connected to the longitudinal end of the second conductor pattern and the longitudinal end of the fourth conductor pattern, and The end portion of the fifth conductor pattern is not electrically connected to the end portion in the longitudinal direction of the second conductor pattern and the end portion in the longitudinal direction of the fourth conductor pattern. The heater according to claim 2.   The heater according to claim 6, wherein the width of the third heating resistor in the lateral direction is larger in the center portion than in the longitudinal direction in the longitudinal direction. A toner formed on a recording material while transporting the recording material at the nip portion, having a cylindrical film, a heater on the inner surface of the film, and a backup member forming a nip portion between the film In an image heating apparatus for heating an image,
An image heating apparatus, wherein the heater is the heater according to claim 1. The image heating apparatus according to claim 8, wherein the heater forms the nip portion together with the backup member via the film.

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