JP5424786B2 - Heater and image heating apparatus equipped with the heater - Google Patents

Description

  The present invention relates to a heater suitable for use in a heating and fixing device mounted in an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer, and an image heating apparatus including the heater.

  As a fixing device mounted on a copying machine or a printer, there is an apparatus having an endless belt, a ceramic heater that contacts an inner surface of the endless belt, and a pressure roller that forms a fixing nip portion with the ceramic heater via the endless belt. . When small-size paper is continuously printed by an image forming apparatus equipped with this fixing device, a phenomenon (temperature increase of the non-sheet passing portion) occurs in which the temperature of the region where the paper does not pass in the longitudinal direction of the fixing nip portion gradually increases. If the temperature of the non-sheet passing part becomes too high, the parts in the device will be damaged, or if printing on large size paper with the non-sheet passing part temperature rise, the non-sheet passing part of small size paper The toner may be offset at a high temperature in a region corresponding to.

  As one method for suppressing the temperature rise of the non-sheet passing portion, it is considered that the heating resistor on the ceramic substrate is formed of a material having a negative resistance temperature characteristic. Since the resistance value of the heating resistor in the non-sheet-passing portion decreases even when the temperature of the non-sheet-passing portion rises, the idea that heat generation in the non-sheet-passing portion can be suppressed even if current flows through the heating resistor in the non-sheet-passing portion It is. The negative resistance temperature characteristic is a characteristic in which the resistance decreases as the temperature increases, and is hereinafter referred to as NTC (Negative Temperature Coefficient). Conversely, it is also considered that the heating resistor is formed of a material having a positive resistance temperature characteristic. When the temperature of the non-sheet-passing part rises, the resistance value of the heating resistor in the non-sheet-passing part increases, and the current flowing through the heating resistor in the non-sheet-passing part is suppressed, thereby suppressing the heat generation in the non-sheet passing part This is the idea. The positive resistance temperature characteristic is a characteristic in which the resistance increases as the temperature rises, and is hereinafter referred to as PTC (Positive Temperature Coefficient).

  However, in general, the material of NTC has a very high volume resistance, and it is very difficult to set the total resistance of the heating resistor formed in one heater within a range that can be used with a commercial power source. On the contrary, the material of PTC has a very low volume resistance, and it is very difficult to set the total resistance of the heating resistor of one heater within a range that can be used with a commercial power source, as in the case of NTC.

  In view of this, the PTC heating resistor formed on the ceramic substrate is divided into a plurality of heating blocks in the longitudinal direction of the heater, and each heating block is configured so that a current flows in the short direction of the heater (the conveyance direction of the recording paper). The two conductors are arranged at both ends of the substrate in the short direction. Further, Patent Document 1 discloses a configuration in which a plurality of heat generating blocks are electrically connected in series. With such a shape, it becomes easy to set the total resistance of the heater within a range that can be used with a commercial power source even in the case of a PTC heating resistor. This document also discloses that a plurality of heating resistors are electrically connected in parallel between two conductors to form a heating block.

JP 2005-209493 A

  However, the resistance value of the conductor is not zero, and the voltage applied to the heating resistor in the central part in one heating block is applied to the heating resistors at both ends due to the influence of the voltage drop generated in the conductor. It turned out to be smaller than the voltage. Since the heat generation amount of the heating resistor is proportional to the square of the applied voltage, the heat generation amount differs between the central portion and both end portions of one heat generation block. In this way, when heat generation unevenness occurs in one heat generation block, heat generation unevenness in the heater longitudinal direction also increases.

  The present invention for solving the above-described problems is connected to a substrate, first and second conductors provided on the substrate, and the first conductor and the second conductor. A heating resistor, wherein the first conductor is provided along a longitudinal direction of the substrate, and the second conductor is different from the first conductor in a lateral direction of the substrate. The heating resistor is electrically connected in parallel between the first conductor and the second conductor, and is electrically connected in parallel. In a heater in which a plurality of heat generating blocks having a plurality of heat generating resistors are provided along the longitudinal direction, and the plurality of heat generating blocks are electrically connected in series, the electrically in series A row having a plurality of heat generating blocks connected to the substrate There are a plurality of the heat generation blocks in the first row so that the end of the heat generation block in the first row and the end of the heat generation block in the second row do not overlap in the longitudinal direction. The position and the position of the heat generating block in the second row are shifted in the longitudinal direction.

  According to the present invention, uneven heat generation distribution in the heater longitudinal direction can be suppressed.

Sectional drawing of the image heating apparatus of this invention. FIG. 2 is a heater configuration diagram according to the first embodiment. Explanatory drawing of heat generation distribution of the heater of Example 1. FIG. Heat generation distribution explanatory drawing of the heater of a comparative example. FIG. 6 is a diagram illustrating a relationship with a paper size of the heater according to the first exemplary embodiment. Explanatory drawing of the non-sheet-passing part temperature rise suppression effect of the heater of Example 1. FIG. The heater block diagram of Example 2. FIG. The heater block diagram of Example 3. FIG.

  FIG. 1 is a cross-sectional view of a fixing device as an example of an image heating device. The fixing device includes a cylindrical film (endless belt) 1, a heater 10 that contacts the inner surface of the film 1, and a pressure roller (nip portion forming member) that forms a fixing nip portion N together with the heater 10 via the film 1. 2 and. The material of the base layer of the film is a heat resistant resin such as polyimide, or a metal such as stainless steel. The pressure roller 2 includes a metal core 2a made of iron or aluminum and an elastic layer 2b made of silicone rubber or the like. The heater 10 is held by a holding member 3 made of heat resistant resin. The holding member 3 also has a guide function for guiding the rotation of the film 1. The pressure roller 2 receives power from a motor (not shown) and rotates in the direction of the arrow. When the pressure roller 2 rotates, the film 1 is driven and rotated.

  The heater 10 includes a ceramic heater substrate 13, a heat generation line A (first row) and a heat generation line B (second row) formed on the substrate 13, and insulation (this embodiment) covering the heat generation lines A and B. In this example, the surface protective layer 14 is made of glass. A temperature detection element 4 such as a thermistor is in contact with the minimum size paper passing area set by the printer on the back side of the heater substrate 13. The electric power supplied from the commercial AC power source to the heat generation line is controlled according to the detected temperature of the temperature detecting element 4. The recording material (paper) P carrying the unfixed toner image is heated and fixed while being nipped and conveyed by the fixing nip N. A safety element 5 such as a thermo switch that contacts when the heater is abnormally heated and shuts off the power supply line to the heat generation line is also in contact with the back side of the heater substrate 13. Similarly to the temperature detection element 4, the safety element 5 is also in contact with the paper passing area of the minimum size paper. Reference numeral 6 denotes a metal stay for applying a spring pressure (not shown) to the holding member 3.

  FIG. 2 is a view for explaining the structure of the heater. 2A is a plan view of the heater, FIG. 2B is an enlarged view showing one heat generation block A1 in the heat generation line A, and FIG. 2C is one heat generation block B1 in the heat generation line B. It is the enlarged view shown. The heating resistors in the heating line A and the heating resistors A1 and B1 in the heating line B are both PTC.

  The heat generation line A (first row) has 20 heat generation blocks A1 to A20, and the heat generation blocks A1 to A20 are connected in series. The heat generation line B (second row) also has 20 heat generation blocks B1 to B20, and the heat generation blocks B1 to B20 are also connected in series. The heat generation line A and the heat generation line B are also electrically connected in series. Electric power is supplied to the heat generation lines A and B from electrodes AE and BE connecting the power feeding connectors.

  The heat generation line A is provided along the longitudinal direction of the substrate at a position different from the conductive pattern Aa (first conductor of the heat generation line A) provided in the longitudinal direction of the substrate and the conductive pattern Aa in the lateral direction of the substrate. The conductive pattern Ab (second conductor of the heat generation line A) is provided. The conductive pattern Aa is divided into 11 (Aa-1 to Aa-11) in the longitudinal direction of the substrate. The conductive pattern Ab is divided into ten (Aa-1 to Aa-10) in the longitudinal direction of the substrate. As shown in FIG. 2B, there are a plurality (eight in this example) between the conductive pattern Aa-1 which is a part of the conductive pattern Aa and the conductive pattern Ab-1 which is a part of the conductive pattern Ab. ) Heating resistors (A1-1 to A1-8) are electrically connected in parallel to form a heating block A1. Also, eight heating resistors (A2-1 to A2-8) are electrically connected in parallel between the conductive pattern Ab-1 and the conductive pattern Aa-2, and the heat generating block A2 (in FIG. 2). Since the part of A2 is omitted, the symbol is omitted). In the heat generation line A, a total of 19 heat generation blocks (A1 to A19) having the same configuration as the heat generation block A1 are provided. However, only the heat generation block A20 in the heat generation line A is different from other heat generation blocks in the length of the heat generation block and the number of heat generation resistors.

  The heat generation line B also has a conductive pattern Ba (first conductor of the heat generation line B) provided along the longitudinal direction of the substrate and the conductive pattern Ba at a position different in the lateral direction of the substrate along the longitudinal direction of the substrate. The conductive pattern Bb (second conductor of the heat generation line B) is provided. The configuration of the heat generation block in the heat generation line B is the same as that of the heat generation line A, and the configuration of the 19 heat generation blocks (B2 to B20) in the heat generation line B is the same as the heat generation block (A1 to A19) of the heat generation line A. is there. Further, only the heat generation block B1 in the heat generation line B is different from other heat generation blocks in the length of the heat generation block and the number of heat generation resistors.

  By the way, as described above, the resistance value of the conductor is not zero, and the voltage applied to the heating resistor in the central portion in one heating block is caused by the resistance of the both ends. It was found to be smaller than the voltage applied to the body. Since the heat generation amount of the heating resistor is proportional to the square of the applied voltage, the heat generation amount differs between the central portion and both end portions of one heat generation block. Specifically, in one heat generating block, the heat generation amount at both ends of the block is the largest, and the heat generation amount in the central portion is small. In this way, when heat generation unevenness occurs in one heat generation block, heat generation unevenness in the heater longitudinal direction also increases.

  Therefore, in the heater of this embodiment, as shown in FIG. 2A, a plurality of rows having a plurality of heat generating blocks electrically connected in series are arranged in a short direction on the substrate (with heat generation lines A and A). Exothermic line B). The end of the heat generating block in the heat generating line A (first row) and the end of the heat generating block in the heat generating line B (second row) do not overlap in the longitudinal direction of the substrate. ) And the position of the heat generation block in the heat generation line B (second row) are shifted in the longitudinal direction of the substrate. Since the position where the heat generation amount in the heat generation line A is large and the position where the heat generation amount in the heat generation line B is large or the position where the heat generation amount is small do not overlap in the longitudinal direction of the substrate, the uneven heat generation distribution in the longitudinal direction of the heater can be reduced.

  A heat distribution unevenness suppressing effect when the heat generation block of the heat generation line A and the heat generation block of the heat generation line B are shifted in the longitudinal direction of the substrate will be described with reference to FIG. 3A is a simulation circuit diagram of the heater, FIG. 3B is a diagram showing the positional relationship between the heat generation block of the heat generation line A and the heat generation block of the heat generation line B, and FIG. 3C is a heat generation distribution diagram of the heater. is there. In FIG. 3A, a simulation circuit diagram is created by simplifying the conditions. In FIG. 3A, the total resistance value of the heating resistor of the heater 10 is about 12.85Ω, the sheet resistance value of the conductive pattern is 0.005Ω / □, and the sheet resistance value of the heating resistor paste is 0.85Ω. / □. These resistance values are values at 200 ° C. The resistance temperature coefficient of the heating resistor paste is 1000 ppm. In FIG. 3A, the resistance values of the heat generating blocks other than the heat generating blocks A7, A8, B7, and B8 are represented as combined resistance values. In the present embodiment, the heat generating blocks are shifted so that both end portions of the heat generating block B7 and the central portions of the heat generating blocks A7 and A8 overlap in the longitudinal direction of the substrate.

  As shown in FIG. 3A, the resistance value of the conductive pattern connecting adjacent heating resistors in one heating block is 0.007Ω. Therefore, the current flowing to the heating resistors located at both ends in one heating block increases, and the current is less likely to flow in the heating resistor located in the center. Therefore, as shown in FIG. 3B, the heat generation block of the heat generation line A and the heat generation block of the heat generation line B are shifted in the longitudinal direction of the substrate. As shown in the temperature distribution of FIG. 3C, when the heat generation block is shifted, the upper and lower limit values of the heat generation distribution are in the range of about ± 3%, and the peak period may be half of the heat generation block length. I understand.

  In contrast, FIGS. 4A to 4C show comparative examples in which the heat generation block of the heat generation line A and the heat generation block of the heat generation line B are completely overlapped without shifting in the longitudinal direction of the substrate. It can be seen that the upper and lower limits of the heat generation distribution are in the range of about ± 8%, and the peak period is the same as the heat generation block length. Comparing the simulation results of FIG. 3 and FIG. 4, the heater of the present embodiment has a variation in the upper and lower limit values of the heat generation distribution that is less than half that of the comparative heater, and the peak period of the heat generation distribution is ½. It can be seen that the heater of this example has less heat distribution unevenness than the heater of the comparative example. The unevenness of heat generation described above becomes more prominent as the resistance component of the conductive pattern becomes higher than the resistance component of the heat generation resistor, and as the number of heat generation resistors in one heat generation block increases. For example, when the sheet resistance value of the conductive pattern of the heater becomes high or the line width of the conductive pattern becomes narrow, the heat generation unevenness occurs more remarkably.

  As described above, there are a plurality of rows having a plurality of heat generation blocks electrically connected in series in the short direction on the substrate, and the positions of the heat generation blocks and the heat generation lines in the heat generation line A (first row). If the position of the heat generation block in B (second row) is shifted in the longitudinal direction of the substrate, uneven heat generation distribution can be suppressed.

  Further, the shape of one heating resistor is not limited to a rectangle as shown in FIG. 2, but is preferably a rectangle. By making the shape rectangular, current can flow through the entire heating resistor. For example, when the shape of the heating resistor is a parallelogram, the shortest path through which current flows easily becomes a part rather than the entire one heating resistor, and a large amount of current concentrates on this shortest path. For this reason, the current distribution flowing through one heat generating resistor is biased, and the effect of suppressing uneven heat distribution is reduced, but this phenomenon can be suppressed by making the shape rectangular. Furthermore, by arranging the heating resistors adjacent to each other so as to partially overlap in the longitudinal direction of the substrate, it is possible to avoid the generation of a region that does not generate heat in the longitudinal direction of the substrate. Thereby, the nonuniformity of the heat generation distribution can be further reduced.

  Next, heat generating blocks (A20 and B1) having different configurations from the other heat generating blocks in the heat generating lines A and B in the heater shown in FIG. 2 will be described. As described above, when the position of the heat generation block of the heat generation line A and the position of the heat generation block of the heat generation line B are shifted in the longitudinal direction of the substrate, the position of the heat generation line B is aligned with the position of the end of the heat generation block A1 in the longitudinal direction of the substrate. There will be no heat generation block. Similarly, the heat generation block of the heat generation line A does not exist at the same position as the end portion of the heat generation block B20. Since only one of the heat generation lines A or B exists in the region at both ends of the heater, the amount of heat generated at both ends becomes small.

  Therefore, in the present embodiment, as described above, the heat generating blocks (A20 and B1) are configured differently from the other heat generating blocks. FIG. 2C shows a configuration of the heat generation block B1 as a representative of the heat generation blocks (A20 and B1). The heat generation block B1 has a block length f in the substrate longitudinal direction that is 1.3 times the block length c of the heat generation blocks B2 to B20 (the relationship between the heat generation block A20 and the heat generation blocks A1 to A19 is the same). The block lengths c and f are heater longitudinal lengths of a region where a heating resistor exists in one heating block. FIG. 2B shows the heat generation block A1 as a representative of the heat generation blocks A1 to A19 and B2 to B20. As described above, the heat generation block A20 and the heat generation block B1 are provided to compensate for a decrease in the heat generation amount at both ends of the heater. Further, although heat generation blocks A20 and B1 for compensating for a decrease in the heat generation amount at both ends of the heater are provided, both ends of the heat generation line A and the heat generation line B are slightly shifted. This is because, as described above, heat generation unevenness occurs in one heat generation block, and thus heat generation unevenness increases if the end portions of the heat generation block A1 and the heat generation block B1 are overlapped in the heater longitudinal direction ( The same applies to the heat generation blocks A20 and B20).

  FIG. 5 is a diagram for explaining the temperature rise of the non-sheet passing portion of the heater 10. FIG. 5 shows a case in which A4 size (210 mm × 297 mm) paper is transported in parallel with the transport direction with respect to the central portion of the heat generation line. The heater 10 in FIG. 5 has a heat generation line length (heat generation area) of 220 mm so that US-LETTER paper (about 216 mm × 279 mm) can also be used. The reason why the heat generation line length is longer than the paper width is to allow the end of the paper to be sufficiently heated even when the paper passing position is shifted in the heater longitudinal direction. When the A4 paper having a paper width of 210 mm is fixed using the heater 10 having a heat generation line length of 220 mm, a non-sheet passing region of 5 mm is generated at both ends of the heat generation line. The heater 10 is power-controlled so that the output of the thermistor 4 provided in the paper passing portion maintains the target temperature. Accordingly, the heater temperature rises in the non-sheet passing portion where the heat is not taken away by the sheet compared to the sheet passing portion.

  FIG. 6 is a simulation circuit diagram and simulation results for explaining the effect of suppressing the temperature rise of the non-sheet passing portion of the heater 10. In FIG. 6A, a simulation circuit diagram is created by simplifying the conditions. In this simulation, the total resistance value of the heater 10 is about 12.85Ω. The sheet resistance value of the conductive pattern is 0.005Ω / □, and the sheet resistance value of the heating element paste is 0.85Ω / □. Further, the resistance temperature coefficient of the heating element paste is set to 1000 ppm. The resistance value per heating resistor included in the heating blocks A1 to A19 and B2 to B20 is 2.23Ω. If adjacent heating resistors in the heating block A1 are connected by a conductive pattern having a line length of 1.3 mm and a line width of 1 mm, the resistance value of the conductive pattern connecting the heating resistors is 0.007Ω. Become. The total resistance value of the heat generation block A1 formed of such heat generation resistors and conductive patterns is about 0.32 Ω. On the other hand, the resistance value around one heating resistor included in the heating blocks A20 and B1 is 2.57Ω. If adjacent heating resistors in the heating block B1 are connected by a conductive pattern having a line length of 2 mm and a line width of 1 mm, the resistance value of the conductive pattern connecting the heating resistors is 0.01Ω. The total resistance value of the heat generating block B1 formed of such heat generating resistors and conductive patterns is about 0.41Ω. In FIG. 6A, the heat generation blocks other than the heat generation blocks A1, A2, and B1 necessary for the explanation are simplified and shown as combined resistance values. The resistance value of the heating resistor is a value at 200 ° C.

  FIG. 6B is an enlarged view of the heat generation blocks A1, A2, and B1 according to this simulation. The simulation was performed in a state where the temperature of the paper passing area was controlled to 200 ° C. and the temperature of the non-paper passing area was raised to 300 ° C. The boundary between the non-sheet passing area and the sheet passing area is 4.125 mm from the left end of the heat generation line A. Since the temperature rises to 300 ° C. in the non-sheet passing region, the resistance values of the heating resistors A1-1 to A1-3 and the heating resistor B1-1 are respectively affected by the resistance temperature coefficient of the heating resistors. It has risen 10%. Since the resistance temperature coefficient of the conductive pattern has little influence, this simulation does not consider the resistance change due to temperature.

  FIG. 6C is a simulation result showing the heat generation distribution of the heater 10 under the above conditions. From the simulation results, it can be seen that the heater 10 generates less heat in the non-sheet passing area than in the sheet passing area. The vertical axis in the figure shows the heat generation amount per unit length in the heater longitudinal direction, taking into account the heat generation amount of the conductive pattern. It can be seen that the average heat generation amount in the non-sheet passing area, excluding the range of 2 mm from the left end of the heating line A where the heat generating line B does not exist, is reduced by about 4% compared to the average in the sheet passing area. In this way, recording is performed so that the boundary between the sheet passing area and the non-sheet passing area is generated in one heat generation block A1, while controlling the power so that the output of the thermistor 4 provided in the sheet passing section maintains the target temperature. When the paper is conveyed, the temperature of the heating resistors (A1-1 to A1-3) existing in the non-sheet passing area rises. Then, since the resistance value of the heating resistor (A1-1 to A1-3) increases, the amount of current flowing through the heating resistor (A1-1 to A1-3) can be reduced. Therefore, the temperature rise of the non-sheet passing portion can be suppressed. When the boundary between the sheet passing area and the non-sheet passing portion area is on the heat generating resistor A1-1 at the extreme end of the heat generating block A1, the effect of connecting a plurality of heat generating resistors in parallel in one heat generating block is reduced. The effect of suppressing the temperature rise of the non-sheet passing portion may not be sufficiently obtained. Therefore, as shown in FIGS. 5 and 6B, the heating resistor A1-1 in the heating block A1, the heating resistor B1-1 in the heating block B1, and the heating resistor A20- in the heating block A20. 7 and by designing the heater so that the sheet does not overlap the heating resistor B20-8 in the heating block B20, the effect of suppressing the temperature rise of the non-sheet passing portion can be effectively obtained.

  FIG. 7 is a diagram illustrating a configuration of the heater 20 according to the second embodiment. The heater 20 has a configuration in which the heat generation line A (first row) and the heat generation line B (second row) can be independently driven by two heater drive circuits. For this purpose, the electrode CE is connected to the heater 10 of the first embodiment. It is added between the heat generation lines A and B. The heat generation line A is supplied with electric power through the electrodes AE and CE, and the heat generation line B is supplied with electric power through the electrodes BE and CE. The configuration is the same as that of the heater 10 except that the electrode CE is added. Thus, the present invention can also be applied to a heater having a configuration in which the heat generation lines A and B can be controlled independently.

  FIG. 8 is a diagram illustrating a configuration of the heater 30 according to the third embodiment. As shown in FIG. 8A, the heat generating blocks A1, A2, B1, and B2 similar to the heater 10 of the first embodiment are provided at both ends of the heater 20 in the longitudinal direction. Between the heat generation block A1 and the heat generation block A2 of the heat generation line A, it is not a heat generation block in which a plurality of PTC heat generation resistors (A1-1 to A1-8, A3-1 to A3-8) are connected in parallel. A heating pattern AP made of a single heating resistor is connected in series with the heating blocks A1 and A2. The heat generation line B has the same configuration as the heat generation line A. This heater 30 also makes the heat generation distribution in the longitudinal direction of the substrate uniform, so that the heat generation block A1 of the heat generation line A does not completely overlap the heat generation block B1 of the heat generation line B in the heater longitudinal direction (of the heat generation block). The heaters are arranged so as to be shifted in the heater longitudinal direction so that the ends do not overlap each other. The positional relationship between the heat generation block A2 and the heat generation block B2 is the same. In this way, the heat generating blocks of each row of the heaters 30 are provided at the ends in the substrate longitudinal direction, and one heater block is provided on the paper passing reference side (in this example, the center side in the substrate longitudinal direction) from this heat generating block. A heating pattern made of a heating resistor is connected.

  FIG. 8B shows an enlarged view of a part of the heat generation block A1 representing the four heat generation blocks and the heat generation pattern AP connected to the heat generation block A1. In the heat generation block A1, eight rectangular heat generation patterns having a line length g and a line width h are arranged and connected in parallel via the conductive patterns Aa-1 and Ab-1. The heat generation blocks A2, B1, and B2 have the same shape. The total resistance value of the heater 30 is about 12.85Ω. In the heat generation blocks A1, A2, B1, and B2, the sheet resistance value of the conductive pattern is 0.005Ω / □, the sheet resistance value of the heat generating paste is 0.85Ω / □, and the resistance value per heating resistor is 2 .23Ω. The dimensions of each part are g = 1.84 mm, h = 0.7 mm, and i = 10.73 mm. If adjacent heating resistors in the heating block A1 are connected by a conductive pattern having a line length of 1.3 mm and a line width of 1 mm, the resistance value of the conductive pattern between the heating resistors is 0.007Ω. The total resistance value of the heat generation block A1 composed of such heat generation resistors and conductive patterns is 0.32 Ω.

  The heat generation pattern AP is a belt-like heat generation pattern extending in the longitudinal direction of the heater with a sheet resistance value of the heat generating paste of 0.047Ω / □, a total resistance of 5.9Ω, a line width of 1.6 mm, and a length of 198 mm. The heating pattern BP is slightly shorter than the heating pattern AP, the sheet resistance value of the heating element paste is 0.047Ω / □, the total resistance is 5.8Ω, the line width is 1.6 mm, and the length is 194 mm. It is a heat generation pattern. A gap between the heat generation block A1 and the heat generation pattern AP is connected by a conductive pattern (j = 0.27 mm). As described above, the heat generation amount per unit length is adjusted by using materials having different resistance values for the sheet resistance of the heating resistor in the heating block A1 and the sheet resistance of the heating pattern AP. As shown in FIG. 8B, when the heat generation block A1 and the heat generation pattern AP are connected in series, a discontinuous heat generation distribution may occur in the conductive pattern portions of these gap portions. However, since the heat generation block A1 of the heat generation line A is shifted in the heater longitudinal direction so as not to completely overlap the heat generation block B1 of the heat generation line B in the heater longitudinal direction, it is discontinuous generated in the gap portion. The influence of heat generation distribution can be reduced.

1 Fixing film 2 Pressure roller 10 Heater A Heat generation line A (first row)
B Heat generation line B (second row)
A1 to A20 Heat generation block of heat generation line A B1 to B20 Heat generation block of heat generation line B Aa, Ab Conductor of heat generation line A Ba, Bb Conductor of heat generation line B A1-1 to A1-8, B1-1 to B1- 8 Heating resistor

Claims (7)

A first and second conductors provided on the substrate; and a heating resistor connected between the first conductor and the second conductor. The conductor is provided along the longitudinal direction of the substrate, and the second conductor is provided along the longitudinal direction at a position different from the first conductor in the lateral direction of the substrate, A plurality of the heating resistors are electrically connected in parallel between the first conductor and the second conductor, and a heating block having the plurality of heating resistors electrically connected in parallel is provided. A plurality of heaters are provided along the longitudinal direction, and the plurality of heat generating blocks are electrically connected in series.
There are a plurality of rows having a plurality of heat generating blocks electrically connected in series in the short direction on the substrate, and the ends of the heat generating blocks in the first row and the rows in the second row The position of the heat generating block in the first row and the position of the heat generating block in the second row are shifted in the longitudinal direction so that end portions of the heat generating blocks do not overlap in the longitudinal direction. heater. The heater according to claim 1, wherein the heating resistor has a positive resistance temperature characteristic. The heater according to claim 1 or 2 , wherein the first row and the second row are electrically connected in series. The heater according to claim 1 or 2 , wherein the first row and the second row are configured to be independently driven. The heater according to any one of claims 1 to 4, wherein a shape of the heating resistor is rectangular, and the heating resistor is disposed so as to partially overlap with the adjacent heating resistor in the longitudinal direction. . The heat generating blocks of each row are provided at the end in the longitudinal direction, and a heat generating pattern composed of a single heat generating resistor is connected to the sheet passing reference side from the heat generating block. The heater as described in any one of Claims 1-5 . An endless belt, a heater that contacts an inner surface of the endless belt, and a nip portion forming member that forms a nip portion together with the heater via the endless belt, and a recording material that carries an image at the nip portion. In an image heating apparatus for heating while nipping and conveying,
An image heating apparatus, wherein the heater is the heater according to any one of claims 1 to 6 .

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