Patent Publication Number: US-11650527-B2

Title: Heater and heating apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 17/088,467, filed on Nov. 3, 2020, which application is a continuation of U.S. patent application Ser. No. 16/722,786, filed on Dec. 20, 2019, now U.S. Pat. No. 10,859,952, issued on Dec. 8, 2020, which application is a continuation of U.S. patent application Ser. No. 16/396,423, filed on Apr. 26, 2019, now U.S. Pat. No. 10,551,776, issued on Feb. 4, 2020, which application is a continuation of U.S. patent application Ser. No. 15/621,498, filed on Jun. 13, 2017, which application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2016-121446, filed on Jun. 20, 2016, and Japanese Patent Application No. 2017-059366, filed on Mar. 24, 2017, the entire contents all of which are incorporated herein by reference. 
    
    
     FIELD 
     Embodiments described herein relate generally to a heater and a heating apparatus. 
     BACKGROUND 
     In a fixing apparatus mounted on an image forming apparatus in the related art, examined to separately dispose a plurality of heat generating bodies in a direction orthogonal to a conveying direction of a sheet and heat a toner image on the sheet. In this case, a gap is necessary between the heating bodies adjacent to each other. However, this gap portion cannot generate heat. Therefore, temperature drops in the gap portion and temperature unevenness occurs. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a configuration diagram showing an image forming apparatus including a fixing apparatus according to a first embodiment; 
         FIG.  2    is an enlarged configuration diagram of a part of an image forming unit in the first embodiment; 
         FIG.  3    is a configuration diagram showing an example of the fixing apparatus according to the first embodiment; 
         FIG.  4    is a block diagram showing a control system of an MFP in the first embodiment; 
         FIG.  5    is a plan view showing a basic configuration of a heating member in the first embodiment; 
         FIG.  6    is an explanatory diagram showing a connection state of a heat generating member group of the heating member shown in  FIG.  5    and driving circuits; 
         FIG.  7    is an explanatory diagram showing a positional relation between the heat generating member group shown in  FIG.  6    and a printing region of a sheet; 
         FIG.  8    is a diagram showing another disposition example of the heat generating member group in the first embodiment; 
         FIG.  9    is a diagram showing still another disposition example of the heat generating member group in the first embodiment; 
         FIGS.  10 A to  10 D  are a perspective view, a sectional view, and schematic sectional views showing the configuration of the heating member in the first embodiment; 
         FIGS.  11 A to  11 D  are a perspective view, a sectional view, and schematic sectional views showing another configuration of the heating member in the first embodiment; 
         FIGS.  12 A and  12 B  are schematic sectional views showing still another configuration of the heating member in the first embodiment; 
         FIGS.  13 A to  13 D  are a perspective view, a sectional view, and schematic sectional views showing the configuration of a heating member in a second embodiment; 
         FIGS.  14 A to  14 D  are a perspective view, a sectional view, and schematic sectional views showing another configuration of the heating member in the second embodiment; 
         FIGS.  15 A and  15 B  are schematic sectional views showing still another configuration of the heating member in the second embodiment; 
         FIG.  16    is a configuration diagram showing a modification of a fixing apparatus according to an embodiment; and 
         FIG.  17    is a flowchart showing a control operation of an MFP in the embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     According to one embodiment, a heater includes a heat-resistant insulating substrate, a plurality of heat generating members arrayed in a first direction on a first surface of the substrate, and a plurality of heat radiating bodies disposed on a surface different from the first surface of the substrate at positions corresponding to gap portions between the heat generating members to passively radiate heat generated thereby. 
     Embodiments are explained below with reference to the drawings. Note that, in the figures, the same portions are denoted by the same reference numerals and signs. 
     First Embodiment 
       FIG.  1    is a configuration diagram showing an image forming apparatus including a heater and a fixing apparatus (a heating apparatus) according to a first embodiment. In  FIG.  1   , an image forming apparatus  10  is, for example, an MFP (Multi-Function Peripherals), which is a compound machine, a printer, or a copying machine. In the following explanation, the MFP is explained as an example. 
     A document table  12  of transparent glass is present in an upper part of a main body  11  of the MFP  10 . An automatic document feeder (ADF)  13  is provided on the document table  12  to be capable of opening and closing. An operation unit  14  is provided in an upper part of the main body  11 . The operation unit  14  includes an operation panel having various keys and a display device of a touch panel type. 
     A scanner unit  15 , which is a reading device, is provided below the ADF  13  in the main body  11 . The scanner unit  15  reads an original document fed by the ADF  13  or an original document placed on the document table  12  and generates image data. The scanner unit  15  includes a contact-type image sensor  16  (hereinafter simply referred to as image sensor). The image sensor  16  is disposed in a main scanning direction. 
     If the image sensor  16  reads an image of the original document placed on the document table  12 , the image sensor  16  reads a document image line by line while moving along the document table  12 . The image sensor  16  executes the line-by-line reading over the entire document size to read the original document for one page. If the image sensor  16  reads an image of the original document fed by the ADF  13 , the image sensor  16  is present in a fixed position (a position shown in the figure). Note that the main scanning direction is a direction orthogonal to a moving direction of the image sensor  16  moving along the document table  12 . 
     Further, the MFP  10  includes a printer unit  17  in the center in the main body  11 . The printer unit  17  processes image data read by the scanner unit  15  or image data created by a personal computer or the like to form an image on a recording medium (e.g., a sheet). The MFP  10  includes, in a lower part of the main body  11 , a plurality of paper feeding cassettes  18  that store sheets of various sizes. Note that, as the recording medium on which an image is formed, there are an OHP sheet and the like besides the sheet. However, in an example explained below, an image is formed on the sheet. 
     The printer unit  17  includes photoconductive drums and includes, as exposing devices a scanning head  19  including LEDs. The printer unit  17  scans the photoconductive drums with rays from the scanning head  19  and generates images. The printer unit  17  is, for example, a color laser printer by a tandem type. The printer unit  17  includes image forming units  20 Y,  20 M,  20 C, and  20 K of respective colors of yellow (Y), magenta (M), cyan (C), and black (K). 
     The image forming units  20 Y,  20 M,  20 C, and  20 K are disposed in parallel from an upstream side to a downstream side on a lower side of an intermediate transfer belt  21 . The scanning head  19  includes a plurality of scanning heads  19 Y,  19 M,  19 C, and  19 K corresponding to the image forming units  20 Y,  20 M,  20 C, and  20 K. 
       FIG.  2    is an enlarged configuration diagram of the image forming unit  20 K among the image forming units  20 Y,  20 M,  20 C, and  20 K. Note that, in the following explanation, the image forming units  20 Y,  20 M,  20 C, and  20 K have the same configuration. Therefore, the image forming unit  20 K is explained as an example. 
     The image forming unit  20 K includes a photoconductive drum  22 K, which is an image bearing body. An electrifying charger (a charging device)  23 K, a developing device  24 K, a primary transfer roller (a transfer device)  25 K, a cleaner  26 K, a blade  27 K, and the like are disposed along a rotating direction t around the photoconductive drum  22 K. Light is irradiated on an exposure position of the photoconductive drum  22 K from the scanning head  19 K to form an electrostatic latent image on the photoconductive drum  22 K. 
     The electrifying charger  23 K of the image forming unit  20 K uniformly charges the surface of the photoconductive drum  22 K. The developing device  24 K supplies, with a developing roller  24   a  to which a developing bias is applied, a black toner to the photoconductive drum  22 K and performs development of the electrostatic latent image. The cleaner  26 K removes a residual toner on the surface of the photoconductive drum  22 K using the blade  27 K. 
     As shown in  FIG.  1   , a toner cartridge  28  that supplies toners to developing devices  24 Y to  24 K is provided above the image forming units  20 Y to  20 K. The toner cartridge  28  includes toner cartridges  28 Y,  28 M,  28 C, and  28 K of the colors of yellow (Y), magenta (M), cyan (C), and black (K). 
     The intermediate transfer belt  21  is stretched and suspended by a driving roller  31  and a driven roller  32  and moves in a cyclical manner. The intermediate transfer belt  21  is opposed to and in contact with photoconductive drums  22 Y to  22 K. A primary transfer voltage is applied to a position of the intermediate transfer belt  21  opposed to the photoconductive drum  22 K by the primary transfer roller  25 K. A toner image on the photoconductive drum  22 K is primarily transferred onto the intermediate transfer belt  21  by the application of the primary transfer voltage. 
     A secondary transfer roller  33  is disposed to be opposed to the driving roller  31  that stretches and suspends the intermediate transfer belt  21 . If a sheet P passes between the driving roller  31  and the secondary transfer roller  33 , a secondary transfer voltage is applied to the sheet P by the secondary transfer roller  33 . The toner image on the intermediate transfer belt  21  is secondarily transferred onto the sheet P. A belt cleaner  34  is provided near the driven roller  32  in the intermediate transfer belt  21 . 
     As shown in  FIG.  1   , paper feeding rollers  35  are provided between the paper feeding cassettes  18  and the secondary transfer roller  33 . The paper feeding rollers  35  convey the sheet P extracted from the paper feeding cassettes  18 . Further, a fixing apparatus  36 , which is a heating apparatus, is provide downstream of the secondary transfer roller  33 . A conveying roller  37  is provided downstream of the fixing apparatus  36 . The conveying roller  37  discharges the sheet P to a paper discharge section  38 . Further, a reversal conveying path  39  is provided downstream of the fixing apparatus  36 . The reversal conveying path  39  reverses the sheet P and guides the sheet P in the direction of the secondary transfer roller  33 . The reversal conveying path  39  is used if duplex printing is performed. 
       FIGS.  1  and  2    show an example of the embodiment. However, the structures of image forming apparatus portions other than the fixing apparatus  36  are not limited to the example shown in  FIGS.  1  and  2   . The structure of a publicly-known electrophotographic image forming apparatus can be used. 
       FIG.  3    is a configuration diagram showing the fixing apparatus  36 , which is the heating apparatus. The fixing apparatus  36  includes a fixing belt (an endless belt)  41 , which is a rotating body, a press roller  42  (a pressurizing roller), belt conveying rollers  43  and  44 , and a tension roller  45 . The fixing belt  41  is an endless belt on which an elastic layer is formed. The fixing belt  41  is rotatably stretched and suspended by the belt conveying rollers  43  and  44  and the tension roller  45 . The tension roller  45  applies predetermined tension to the fixing belt  41 . 
     A tabular heating member  46  (a heater) is provided between the belt conveying rollers  43  and  44  on the inner side of the fixing belt  41 . The heating member  46  is in contact with the inner side of the fixing belt  41 . The heating member  46  is disposed to be opposed to the press roller  42  via the fixing belt  41 . The heating member  46  is pressed in the direction of the press roller  42  and forms a fixing nip having a predetermined width between the fixing belt  41  and the press roller  42 . 
     If the sheet P passes the fixing nip, a toner image on the sheet P is fixed on the sheet P with heat and pressure. A driving force is transmitted to the press roller  42  by a motor and the press roller  42  rotates (a rotating direction is indicated by an arrow t in  FIG.  3   ). The fixing belt  41 , the belt conveying rollers  43  and  44 , and the tension roller  45  rotate following the rotation of the press roller  42  (a rotating direction of the fixing belt  41 , the belt conveying rollers  43  and  44 , and the tension roller  45  is indicated by an arrow s shown in  FIG.  3   ). 
     In the fixing belt  41 , which is the rotating body, a silicon rubber layer (an elastic layer) having thickness of 200 μm (micrometers) is formed, for example, on the outer side on a SUS or nickel substrate having thickness of 50 μm or polyimide, which is heat-resistant resin having thickness of 70 μm. The outermost circumference of the fixing belt  41  is covered by a surface protecting layer of PFA or the like. In the press roller  42 , which is the pressurizing body, for example, a silicon sponge layer having thickness of 5 mm is formed on the surface of an iron bar of ϕ10 mm. The outermost circumference of the press roller  42  is covered by a surface protecting layer of PFA or the like. A detailed configuration of the heating member  46  is explained below. 
       FIG.  4    is a block diagram showing a configuration example of a control system of the MFP  10  in the first embodiment. The control system includes, for example, a CPU  100  that controls the entire MFP  10 , a bus line  110 , a read only memory (ROM)  120 , and a random access memory (RAM)  121 . The control system includes an interface (I/F)  122 , the scanner unit  15 , an input and output control circuit  123 , a paper feed and conveyance control circuit  130 , an image formation control circuit  140 , and a fixing control circuit  150 . The CPU  100  and the circuits are connected via the bus line  110 . 
     The CPU  100  controls the entire MFP  10 . The CPU  100  realizes a processing function for image formation by executing a computer program stored in the ROM  120  or the RAM  121 . The ROM  120  stores a control program, control data, and the like for controlling a basic operation of image formation processing. The RAM  121  is a working memory. 
     The ROM  120  (or the RAM  121 ) stores, for example, control programs for the image forming unit  20 , the fixing apparatus  36 , and the like and various control data used by the control programs. Specific examples of the control data in this embodiment include a correspondence relation between the size (the width in the main scanning direction) of a printing region in a sheet and a heat generating member to be energized. 
     A fixing temperature control program of the fixing apparatus  36  includes a determination logic for determining the size of an image forming region in a sheet on which a toner image is formed. The fixing temperature control program includes a heating control logic for selecting a switching element of a heat generating member corresponding to a position where the image forming region passes and energizing the switching element before the sheet is conveyed into the inside of the fixing apparatus  36  and controlling heating in the heating member  46 . 
     The I/F  122  performs communication with various apparatuses such as a user terminal and a facsimile. The input and output control circuit  123  controls an operation panel  14   a  and a display device  14   b . An operator can designate, for example, a sheet size and the number of copies of an original document by operating the operation panel  14   a.    
     The paper feed and conveyance control circuit  130  controls a motor group  131  and the like that drive the paper feeding rollers  35 , the conveying roller  37  in a conveying path, or the like. The paper feed and conveyance control circuit  130  controls the motor group  131  and the like on the basis of control signals from the CPU  100 . The paper feed and conveyance control circuit  130  controls the motor group  131  and the like taking into account detection results of various sensors  132  near the paper feeding cassettes  18  or on the conveying path. 
     The image formation control circuit  140  controls the photoconductive drum  22 , the charging device  23 , the exposing device (the scanning head)  19 , the developing device  24 , and the transfer device  25  respectively on the basis of control signals from the CPU  100 . 
     The fixing control circuit  150  controls, on the basis of a control signal from the CPU  100 , a driving motor  151  that rotates the press roller  42  of the fixing apparatus  36 . The fixing control circuit  150  controls energization to a heat generating member (explained below) of the heating member  46 . The fixing control circuit  150  receives input of temperature information of the heating member  46  from a temperature detecting member  152  such as a thermistor and controls the temperature of the heating member  46 . 
     Note that, in this embodiment, the control program and the control data of the fixing apparatus  36  are stored in a storage device of the MFP  10  and executed by the CPU  100 . However, an arithmetic operation device and a storage device may be separately provided exclusively for the fixing apparatus  36 . 
       FIG.  5    is a plan view showing a basic configuration of the heating member  46  (the heater) in the first embodiment. The heating member  46  is configured by a heating member group. As shown in  FIG.  5   , in the heating member  46 , a plurality of heat generating members  51  having a predetermined width are arrayed in a longitudinal direction (the left-right direction in the figure) on a heat-resistant insulating substrate, for example, a ceramic substrate  50 . 
     The heat generating members  51  are formed, for example, directly or by stacking a glaze layer and a heat generation resistance layer on one surface of the ceramic substrate  50 . As explained above, the heat generation resistance layer configures the heat generating members  51 . The heat generation resistance layer is formed of a known material such as TaSiO 2 . The heat generating members  51  are divided into a predetermined length and a predetermined number of pieces in the longitudinal direction of the heating member  46 . Details of the disposition of the heat generating members  51  are explained below. Electrodes  52   a  and  52   b  are formed at both end portions in a latitudinal direction of the heating member  46 , that is, a sheet conveying direction of the heat generating members  51  (the vertical direction in the figure). 
     Note that the sheet conveying direction (the latitudinal direction of the heating member  46 ) is explained as a Y direction in the following explanation. The longitudinal direction of the heating member  46  is a direction orthogonal to the sheet conveying direction. The longitudinal direction of the heating member  46  corresponds to the main scanning direction in forming an image on a sheet, that is, a sheet width direction. The longitudinal direction of the heating member  46  is explained as an X direction in the following explanation. 
       FIG.  6    is an explanatory diagram showing a connection state of the heat generating member group of the heating member  46  shown in  FIG.  5    and a driving circuit for the heat generating member group. In  FIG.  6   , the plurality of heat generating members  51  are respectively individually controlled to be energized by a plurality of driving ICs (integrated circuits)  531 ,  532 ,  533 , and  534 . That is, the electrodes  52   a  of the heat generating members  51  are connected to one end of a driving source  54  via the driving ICs  531 ,  532 ,  533 , and  534 . The electrodes  52   b  of the heat generating member  51  are connected to the other end of the driving source  54 . 
     As specific examples of the driving ICs  531  to  534 , a switching element formed by an FET, a triac, a switching IC, and the like can be used. Switches of the driving ICs  531  to  534  are turned on, whereby the heat generating members  51  are energized by the driving source  54 . Therefore, the driving ICs  531  to  534  configure switching units of the heat generating members  51 . As the driving source  54 , for example, an AC power supply (AC) and a DC powers supply (DC) can be used. Note that, in the following explanation, the driving ICs  531  to  534  are sometimes collectively referred to as driving ICs  53 . 
     A thermostat  55  may be connected to the driving source  54  in series. The thermostat  55  is turned off if the temperature of the heating member  46  reaches temperature (a dangerous temperature) set in advance. If the thermostat  55  is turned off, the thermostat  55  disconnects the driving source  54  and the heat generating members  51  and prevents the heating member  46  from being abnormally heated. 
       FIG.  7    is a diagram for explaining a positional relation between the heat generating member group shown in  FIG.  6    and a printing region of a sheet. In  FIG.  7   , assumed that the sheet P is conveyed in an arrow Y direction. In  FIG.  7   , a state in shown in which the switch of the driving IC  53  connected to the heat generating member  51  present in a position corresponding to the printing region of the sheet (width W of an image forming region) is selectively turned on and the heat generating member  51  is energized and heated. That is, only the printing region of the sheet P is intensively heated. 
     Before the sheet P is conveyed into the fixing apparatus  36 , the size of the printing region of the sheet P is determined. As a method of determining the printing region of the sheet P, there is a method of using an analysis result of image data read by the scanner unit  15  and image data created by a personal computer or the like. There is also a method of determining the printing region on the basis of printing format information such as margin setting on the sheet P. Further, there is, for example, a method of determining the printing region on the basis of a detection result of an optical sensor. 
       FIG.  8    is a diagram showing another disposition example of the heat generating member group in the first embodiment. There are various sizes of the sheet P conveyed to the fixing apparatus  36 . For example, an A5 size (148 mm), an A4 size (210 mm), a B4 size (257 mm), and an A4 landscape size (297 mm) are relatively often used. 
     Therefore, in  FIG.  8   , the heat generating members  51  having a plurality of kinds of widths are arrayed in the X direction to correspond to sheet sizes (the four kinds of sizes explained above). The heat generating member group is energized to have a margin of approximately 5% in a heating region taking into account conveyance accuracy and generation of a skew of a conveyed sheet or release of heat to a non-heated portion. 
     For example, among the four kinds of sizes, a first heat generating member  511  is provided in the center in the X direction to correspond to the width (148 mm) of the A5 size, which is the minimum size. Second heat generating members  512  and  513  are provided on the outer side in the X direction of the first heat generating member  511  to correspond to the width (210 mm) of the A4 size larger than the A5 size. Similarly, third heat generating members  514  and  515  are provided on the outer side of the second heat generating members  512  and  513  to correspond to the width (257 mm) of the B4 size larger than the A4 size. Fourth heat generating members  516  and  517  are provided on the outer side of the third heat generating members  514  and  515  to correspond to the width (297 mm) of the A4 landscape size larger than the B4 size. 
     The electrodes  52   a  of the heat generating members ( 511  to  517 ) are connected to one end of the driving source  54  via the driving ICs  531  to  537 . The electrodes  52   b  are connected to the other end of the driving source  54 . Note that the number of the heat generating members ( 511  to  517 ) and the widths of the heat generating members ( 511  to  517 ) shown in  FIG.  8    are described as an example and are not limited to the example. 
     In  FIG.  8   , the sheet P is conveyed along the center of the conveying path. If the sheet P of the minimum size (A5) is conveyed, only the driving IC  531  connected to the first heat generating member  511  in the center is switched on. As the size of the sheet P increases, the driving ICs ( 532  to  537 ) connected to the second to fourth heat generating members ( 512  to  517 ) are respectively sequentially switched on. 
       FIG.  9    is a diagram showing still another disposition example of the heat generating member group in the first embodiment. In  FIG.  9   , an example is shown in which the sheet P is conveyed along one end portion (e.g., the left side) of the conveying path of the sheet P. As in  FIG.  8   , the heat generating members  51  having the plurality of kinds of width are arrayed in the X direction to correspond to the four kinds of sheet sizes. 
     For example, the first heat generating member  511  is provided on the leftmost side in the X direction to correspond to the width of the A5 size, which is the minimum size, among the four kinds of sizes. The second heat generating member  512  is provided on the right side of the heat generating member  511  to correspond to the width of the A4 size larger than the A5 size. Similarly, the third heat generating member  513  is provided on the right side of the second heat generating member  512  to correspond to the width of the B4 size larger than the A4 size. The fourth heat generating member  514  is provided on the right side of the third heat generating member  513  to correspond to the width of the A4 landscape size larger than the B4 size. 
     The electrodes  52   a  of the heat generating members ( 511  to  514 ) are connected to one end of the driving source  54  via the driving ICs  531  to  534 . The electrodes  52   b  of the heat generating members ( 511  to  514 ) are connected to the other end of the driving source  54 . Note that the number of the heat generating members ( 511  to  514 ) and the widths of the heat generating members shown in  FIG.  9    are described as an example and are not limited to the example. 
     In  FIG.  9   , if the sheet P of the minimum size (A5) is conveyed, only the driving IC  531  connected to the first heat generating member  511  on the leftmost side is switched on. As the size of the sheet P increases, the driving ICs ( 532  to  534 ) connected to the second to fourth heat generating members ( 512  to  514 ) are respectively sequentially switched on. 
     In this embodiment, a line sensor  40  (see  FIG.  1   ) is disposed in a paper passing region. The line sensor  40  determines a size and a position of a passing sheet on a real-time basis. Alternatively, the line sensor  40  may determine a sheet size during a start of a printing operation from image data or information concerning the paper feeding cassettes  18  in which sheets are stored in the MFP  10 . 
     Incidentally, in the heating member  46  shown in  FIGS.  5  and  6   , a gap  56  is present between the heat generating members  51  adjacent to each other. Similarly, in the heating member  46  shown in  FIGS.  8  and  9   , the gap  56  is present between the heat generating members adjacent to each other. This gap  56  portion cannot generate heat. Therefore, a temperature drop occurs in the gap portion. If the temperature drop occurs, heat generation unevenness occurs in a direction orthogonal to a conveying direction Y of a sheet. The heat generation unevenness affects fixing quality. In particular, in the case of color printing, it is likely that differences occur in color development and gloss. Therefore, the temperature of the heating member  46  needs to be equalized. 
     Therefore, in the heater and the fixing apparatus according to the first embodiment, a ceramic substrate is formed in a multiplayer structure. The plurality of heat generating members  51  are arrayed in the X direction on a first surface (a first layer) of the ceramic substrate. A heat radiating body that actively or passively generates heat (radiates stored heat) is disposed on a second surface (a second layer) to compensate for gaps among the plurality of heat generating members  51 . That is, the heat radiating body disposed on the second surface corresponding to gap portions among the plurality of heat generating members. 
       FIGS.  10 A to  10 D  are diagrams showing the configuration of the heating member  46  (the heater) according to the first embodiment.  FIG.  10 A  is a perspective view. The heating member  46  shown in  FIG.  10 A  corresponds to an example in which the plurality of heat generating members  51  having fixed width are arrayed in the X direction as shown in  FIG.  5   . 
     As shown in  FIG.  10 A , the ceramic substrate  50 , which is the heat-resistant insulating substrate, is formed in a multilayer structure including a ceramic substrate  501  of a first layer and a ceramic substrate  502  of a second layer. Note that the ceramic substrate  501  of the first layer forms a layer configuring a main body portion in the ceramic substrate  50 , that is, a base layer. 
     A heat generation resistance layer is directly stacked on a first surface (e.g., the ceramic substrate  501  of the first layer) of the ceramic substrate  50 . A heat generation resistance layer is directly stacked on a second surface (e.g., the ceramic substrate  502  of the second layer) of the ceramic substrate  50 . The heat generation resistance layers configure the heat generating members  51 . The heat generating members  51  are formed of a known material such as TaSiO 2 . Alternatively, the heat generating members  51  may be configured by stacking glaze layers and heat generation resistance layers on the ceramic substrates  501  and  502 . The plurality of heat generating members  51  on the second surface are members for temperature equalization and configure a heat radiating body that actively radiates stored heat. 
     The heat generating members  51  on the ceramic substrate  501  of the first layer are arrayed in the longitudinal direction (the X direction) of the ceramic substrate  501  with predetermined gaps  57  apart from one another. The heat generating members  51  on the ceramic substrate  502  of the second layer are also arrayed in the longitudinal direction (the X direction) of the ceramic substrate  502  with the predetermined gaps  57  apart from one another. 
     However, the heat generating members  51  disposed on the second layer are disposed to compensate for the gaps  57  among the heat generating members  51  of the first layer. That is, the heat generating members  51  of the first layer and the heat generating members  51  of the second layer are alternately disposed in the vertical direction. The end portions in the X direction of the heat generating members  51  of the first layer and the heat generating members  51  of the second layer overlap each other. 
     Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed in the X direction without a gap and can be controlled to uniform temperature. Further, a protecting layer  503  may be provided on the ceramic substrate  502  of the second layer. The protecting layer  503  is made of a material different from the ceramic substrate. The protecting layer  503  is formed of, for example, Si 3 N 4  to cover the heat generating members  51 . 
       FIG.  10 B  is a sectional view of the heating member  46  viewed from an arrow A direction of  FIG.  10 A . As shown in  FIG.  10 B , the heat generating members  51  are formed in multiple layers on the ceramic substrates  501  and  502 . A method of forming the heat generating members  51  (the heat generation resistance layers) is the same as a known method (e.g., a method of forming a thermal head). A masking layer is formed of aluminum on the heat generation resistance layers. In heat generating members adjacent to each other are insulated. Aluminum layers (the electrodes  52   a  and  52   b ) are formed in a pattern in which the heat generating members  51  are exposed in the Y direction. 
     Electric conductors  58  for wiring are connected to the aluminum layers (the electrodes  52   a  and  52   b ) at both ends of the heat generating members  51 . The electric conductors  58  are connected to, by through-hole patterns (silver paste is filled in through-holes), wiring patterns  59  formed on the ceramic substrates  501  and  502  by screen printing or the like. The wiring patterns  59  are respectively joined to the switching elements of the driving ICs  53 . Therefore, power feed to the heat generating members  51  is performed from the driving source  54  via the wiring patterns  59 , the electric conductors  58 , and the switching elements of the driving ICs  53 . 
     Further, the protecting layer  503  is formed in a top section to cover all of the heat generating members  51 , the aluminum layers (the electrodes  52   a  and  52   b ), the electric conductors  58 , and the like on the ceramic substrate  502  of the second layer. AC or DC is supplied to the heat generating member group from the driving source  54 . Note that the switching elements (triacs or FETs) of the driving ICs are desirably switched by a zero-cross circuit to take into account flicker. 
       FIG.  10 C  is a schematic sectional view of the heating member  46  viewed from the Y direction. As it is seen from  FIG.  10 C , the heat generating members  51  are arrayed on the ceramic substrate  501  of the first layer and the ceramic substrate  502  of the second layer. The heat generating members  51  of the first layer are arrayed in the X direction of the ceramic substrate  501  with the gaps  57  having the predetermined width apart from one another. The heat generating members  51  of the second layer are arrayed with the gaps  57  having the predetermined width apart from one another to compensate for the gaps  57  of the first layer. 
     The heat generating members  51  of the first layer and the heat generating members  51  of the second layer are alternately disposed in the vertical direction. The end portions in the X direction of the heat generating members  51  of the first layer and the heat generating members  51  of the second layer overlap each other. Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed in the X direction without a gap and can be controlled to uniform temperature. 
       FIG.  10 D  is a schematic sectional view showing another example of the heating member  46 . The heating member  46  of  FIG.  10 D  corresponds to the example shown in  FIG.  8   . In  FIG.  10 D , only the heat generating members  511 ,  512 ,  514 , and  516  are shown. The heat generating members  511 ,  513 ,  515 , and  517  are symmetrical to the disposition of the heat generating members  511 ,  512 ,  514 , and  516 . Illustration of the heat generating members  511 ,  513 ,  515 , and  517  is omitted. 
     In the example shown in  FIG.  10 D , the heat generating members  516  and  512  on the ceramic substrate  501  of the first layer are arrayed in the X direction on the ceramic substrate  501  with the gap  57  having the predetermined width apart from each other. The heat generating members  514  and  511  on the ceramic substrate  502  of the second layer are disposed with the gap  57  having the predetermined width apart from each other to compensate for the gap  57  of the first layer. 
     The heat generating members ( 516  and  512 ) of the first layer and the heat generating members ( 514  and  511 ) of the second layer are alternately disposed in the vertical direction. Both the end portions in the X direction of the heat generating members of the first layer overlap both the end portions in the X direction of the heat generating members of the second layer. Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed in the X direction without a gap and can be controlled to uniform temperature. 
     By equalizing the temperature of the heating member  46 , possible to reduce temperature unevenness of the fixing belt  41  and achieve temperature equalization. Therefore, toner uniformly adheres during image formation, color unevenness decreases, and the quality of an image can be improved. 
     Note that the heating member  46  shown in  FIG.  10 D  corresponds to the example shown in  FIG.  8   . However, the heating member  46  can also be configured to correspond to the example shown in  FIG.  9   . That is, the heat generating members  511  and  513  shown in  FIG.  9    may be disposed on the ceramic substrate  501  with the gap  57  apart from each other. The heat generating members  512  and  514  may be disposed on the ceramic substrate  502  with the gap  57  apart from each other. In this case, both the end portions in the X direction of the heat generating members of the first layer are also arrayed to overlap both the end portions in the X direction of the heat generating members of the second layer. 
     It is possible to further achieve the temperature equalization if the heat generating members on the first surface (the first layer) and the heat generating members on the second surface (the second layer) are set such that a heat generation amount of the heat generating members of a layer (the first layer) far from the surface of the ceramic substrate  50  (a position where the heating member  46  is in contact with the fixing belt  41 ) is large. 
     That is, if the heating member  46  is set in contact with the fixing belt  41 , the ceramic substrate  501  of the first layer forming the base layer of the ceramic substrate  50  is located at a distance away from the fixing belt  41 . Therefore, a heat generation amount of the heat generating members  51  of the first layer is set larger than a heat generation amount of the heat generating members  51  of the second layer closer to the fixing belt  41 . Therefore, a heat generation amount in the longitudinal direction of the heating member  46  in contact with the fixing belt  41  is substantially uniform. It is possible to heat the fixing belt  41  at uniform temperature. 
     To increase a heat generation amount of the heat generating members in a layer far from the position in contact with the fixing belt  41 , a heat generation resistance layer made of a different material is desirably used. Alternatively, to increase the heat generation amount, a heat generation resistance layer having large thickness is desirably formed of the same material. If viewed from the surface of the ceramic substrate  50 , the length in the Y direction of the heat generating member of the far layer may be reduced. 
     In this way, the heating member  46  sets the heat generation amount of the heat generating members on the first surface and the heat generation amount of the heat generating members (the heat radiating body) on the second surface to be different. That is, possible to further achieve the temperature equalization by setting the heat generation amount of the heat generating members  51  present in the layer (the first layer) far from the contact position (a nip) with the fixing belt  41  to be larger than the heat generation amount of the heat generating members  51  present in the layer (the second layer) close to the contact position. 
       FIGS.  11 A to  11 D  are diagrams showing another configuration of the heating member  46  (the heater) according to the first embodiment.  FIG.  11 A  is a perspective view. In the heating member  46 , pluralities of heat generating members  51  having fixed width are arrayed in the X direction on both surfaces of a single insulating substrate (e.g., the ceramic substrate  501 ). Note that, in  FIGS.  11 A to  11 D , a surface on the upper side of the ceramic substrate  501  is assumed to be a front surface and a surface on the lower surface is assumed to be a rear surface. 
     Heat generation resistance layers are respectively directly stacked and formed on the rear surface (the first surface) and the front surface (the second surface) of the ceramic substrate  501 . Alternatively, glaze layers and heat generation resistance layers may be stacked and formed on the rear surface and the front surface of the ceramic substrate  501 . The heat generation resistance layers configure the heat generating members  51  and are formed of a known material such as TaSiO 2 . 
     The heat generating members  51  formed on the rear surface (the first surface) of the ceramic substrate  501  are arrayed in the longitudinal direction (the X direction) with the predetermined gaps  57  apart from one another. The heat generating members  51  formed on the front surface (the second surface) of the ceramic substrate  501  are also arrayed in the longitudinal direction (the X direction) with the predetermined gaps  57  apart from one another. However, the heat generating members  51  disposed on the front surface are disposed to compensate for the gaps  57  among the heat generating members  51  on the rear surface. The end portions in the X direction of the heat generating members  51  disposed on the rear surface and the heat generating members  51  disposed on the front surface overlap each other. 
     Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed in the X direction without a gap and can be controlled to uniform temperature. Further, the protecting layer  503  may be provided on the upper surface side of the ceramic substrate  501 . A protecting layer  504  may be provided on the lower surface side. The protecting layers  503  and  504  are formed of, for example, Si 3 N 4 . 
       FIG.  11 B  is a sectional view of the heating member  46  viewed from an arrow A direction in  FIG.  11 A . As shown in  FIG.  11 B , the heat generating members  51  are formed on both the surfaces of the ceramic substrate  501 . The aluminum layers (the electrodes  52   a  and  52   b ) are formed in a pattern in which the heat generating members  51  are exposed in the Y direction. 
     The electric conductors  58  for wiring are connected to the electrodes  52   a  and  52   b  at both ends of the heat generating members  51 . The electric conductors  58  are connected to wiring patterns  59  formed on the ceramic substrate  501  by screen printing or the like. The wiring patterns  59  are respectively joined to the switching elements of the driving ICs  53 . 
     In  FIGS.  11 A to  11 D , since the disposition of the heat generating members  51  is mainly explained, details of the wiring patterns  59  are omitted. However, if the width in the Y direction of the ceramic substrate  50  is increased, a space for forming the wiring patterns  59  can be secured. In this way, power feed to the heat generating members  51  is performed from the driving source  54  via the wiring patterns  59 , the electric conductors  58 , and the switching elements of the driving ICs  53 . 
       FIG.  11 C  is a schematic sectional view of the heating member  46  viewed from the Y direction. The heat generating members  51  on the rear surface side of the ceramic substrate  501  are arrayed in the X direction with the gaps  57  having the predetermined width apart from one another. The heat generating members  51  on the front surface side are arrayed with the gaps  57  having the predetermined with apart from one another to compensate for the gaps  57  on the rear surface side. 
     The heat generating members  51  on the rear surface side and the heat generating members  51  on the front surface side are alternately disposed in the vertical direction. The end portions in the X direction of the respective heat generating members  51  overlap each other. Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed in the X direction without a gap. Therefore, possible to control the heating member  46  to uniform temperature. 
       FIG.  11 D  is a schematic sectional view showing another example of the heating member  46 . The heating member  46  shown in  FIG.  11 D  corresponds to the example shown in  FIG.  8   . In  FIG.  11 D , only the heat generating members  511 ,  512 ,  514 , and  516  are shown. The heat generating members  511 ,  513 ,  515 , and  517  are symmetrical to the disposition of the heat generating members  511 ,  512 ,  514 , and  516 . Illustration of the heat generating members  511 ,  513 ,  515 , and  517  is omitted. 
     In the example shown in  FIG.  11 D , the heat generating members  516  and  512  are arrayed in the X direction with the gap  57  having the predetermined width apart from each other on the rear surface side of the ceramic substrate  501 . The heat generating members  514  and  511  are arrayed in the X direction with the gap  57  having the predetermined with apart from each other on the front surface side of the ceramic substrate  501  to compensate for the gap  57 . The heat generating members ( 516  and  512 ) on the rear surface side and the heat generating members ( 514  and  511 ) on the front surface side are alternately disposed in the vertical direction. Both the end portions in the X direction of the respective heat generating members overlap. 
     Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed in the X direction without a gap. Therefore, possible to control the heating member  46  to uniform temperature. By equalizing the temperature of the heating member  46 , possible to reduce temperature unevenness of the fixing belt  41  and achieve temperature equalization and improve quality during image formation. 
     Note that the heat generating members on the first surface (the rear surface) and the heat generating members on the second surface (the front surface) are desirably set such that a heat generation amount of the heat generating members on the surface (the rear surface) far from the surface of the ceramic substrate  501  (a position where the heating member  46  is in contact with the fixing belt  41 ) is large. As a result, possible to further equalize the temperature of the heating member  46 . 
     Note that the heating member  46  shown in  FIG.  11 D  corresponds to the example shown in  FIG.  8   . However, the heating member  46  can also be configured to correspond to the example shown in  FIG.  9   . That is, the heat generating members  511  and  513  shown in  FIG.  9    are disposed with the gap  57  apart from each other on the first surface (e.g., the rear surface) of the ceramic substrate  501 . The heat generating members  512  and  514  are disposed with the gap  57  apart from each other on the second surface (e.g., the front surface) to compensate for the gap  57 . In this case, both the end portions in the X direction of the heat generating members on the first surface are arrayed to overlap both the end portions in the X direction of the heat generating members on the second surface. 
       FIGS.  12 A and  12 B  are schematic sectional views showing another modification of the heating member  46 .  FIGS.  12 A and  12 B  are a modification of the array of the heat generating member  51  of the first layer and the heat generating members  51  of the second layer shown in  FIG.  10 C . As shown in  FIG.  12 A , the heat generating members  51  are arrayed on the ceramic substrates  501  and  502  of the first layer and the second layer. The heat generating members  51  of the first layer are arrayed in the X direction of the ceramic substrate  501  with the gaps  57  having the predetermined width apart from one another. The heat generating members  51  in the second layer are arrayed with the gaps  57  having the predetermined with apart from one another to compensate for the gaps  57  of the first layer. 
     The heat generating members  51  of the first layer and the heat generating members  51  of the second layer are alternately disposed in the vertical direction. However, the heat generating members  51  of the first layer and the heat generating members  51  of the second layer coincide with the gaps  57  opposed thereto without the end portions in the X direction thereof overlapping. That is, the gaps  57  are set to coincide with the width in the X direction of the heat generating members  51  of the first layer and the heat generating members  51  of the second layer. 
     Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed in the X direction without a gap and can be controlled to uniform temperature. As shown in  FIG.  10 C , the heat generating members  51  of the first layer and the heat generating members  51  of the second layer do not overlap. However, the gaps  57  of the first layer are compensated by the heat generating members  51  of the second layer. Therefore, possible to suppress a temperature drop of the gap  57  portions. 
       FIG.  12 B  is still another modification of the heating member  46 . The heat generating members  51  are arrayed in the X direction with the gaps  57  having the predetermined width apart from one another respectively on the ceramic substrates  501  and  502  of the first layer and the second layer. The heat generating members  51  of the first layer and the heat generating members  51  of the second layer are alternately disposed in the vertical direction. 
     However, the end portions in the X direction of the heat generating members  51  of the first layer and the heat generating members  51  of the second layer do not overlap. The gaps  57  are set lightly larger than the width in the X direction of the heat generating members  51  of the first layer and the second layer. Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed in the X direction with a few gaps. 
     In the example shown in  FIG.  12 B , the end portions of the heat generating members  51  of the first layer and the second layer do not overlap unlike the end portions shown in  FIG.  10 D . However, since most of the gaps  57  of the first layer are compensated by the heat generating members  51  of the second layer, there is an effect of suppressing a temperature drop of the gap  57  portions. 
     Note that the configuration in which the heat generating members  51  of the first layer and the heat generating members  51  of the second layer do not overlap can be applied to the heating member  46  shown in  FIGS.  8  and  9   . Similarly, the configuration can also be applied to the heating member  46  formed on the ceramic substrate  501  having a single layer structure shown in  FIGS.  11 A to  11 D . 
     As explained above, with the heater and the fixing apparatus according to the first embodiment, in the plurality of heat generating members in the heating member  46  (the heater), insulation among the heat generating members is secured and occurrence of temperature unevenness can be reduced. 
     Note that, in the first embodiment, ceramics is explained as the example of the heat-resistant insulating substrate. However, it is evident that the same effect is obtained with a heat-resistant insulating substrate such as a glass epoxy substrate or a glass composite substrate. A higher layer in an upper part of a heat generation resistance layer may be made of SiO 2 . 
     Second Embodiment 
     A heater and a fixing apparatus according to a second embodiment are explained. In the heating member  46  in the second embodiment, a ceramic substrate is formed in, for example, a multilayer structure and a plurality of heat generating members  51  are arrayed in the X direction on a first surface of the ceramic substrate (on the ceramic substrate of the first layer). A plurality of good heat conductors  60  are arrayed on a second surface (on the ceramic substrate of the second layer) to compensate for gaps among the plurality of heat generating members. The plurality of good heat conductors  60  on the second surface are members for temperature equalization and configure a heat radiating body that passively generates heat (radiates stored heat). 
       FIGS.  13 A to  13 D  are diagrams showing the configuration of the heating member  46  according to the second embodiment.  FIG.  13 A  is a perspective view. The heating member  46  shown in  FIG.  13 A  corresponds to the example in which the heat generating members  51  having the fixed width are arrayed in the X direction as shown in  FIG.  5   . 
     As shown in  FIG.  13 A , the ceramic substrate  50 , which is the heat-resistant insulating substrate, is formed in a multilayer structure including the ceramic substrate  501  of the first layer and the ceramic substrate  502  of the second layer. A heat generation resistance layer is directly stacked on the ceramic substrate  501  of the first layer. Alternatively, a glaze layer and a heat generation resistance layer are stacked on the ceramic substrate  501  of the first layer. The heat generating resistance layer configures the heat generating members  51 . The heat generating members  51  are formed on a known material such as TaSiO 2 . 
     The good heat conductors  60  are arrayed on the ceramic substrate  502  of the second layer with predetermined gaps apart from one another to compensate for gap  56  portions among the heat generating members  51  on the ceramic substrate  501  of the first layer. The good heat conductors  60  are members for temperature equalization made of a metal layer of aluminum, copper, or the like. The good heat conductors  60  receive the heat of the heat generating members  51  of the first layer to generate heat. That is, the good heat conductors  60  configure a heat radiating body that passively radiates stored heat. The end portions in the X direction of the heat generating members  51  of the first layer and the good heat conductors  60  of the second layer overlap each other. 
     Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed in the X direction such that the gaps  56  are hidden by the good heat conductors  60 . The heat of the heat generating members  51  is transmitted to the good heat conductors  60  to reduce a temperature drop in the gap  56  portions. Consequently, possible to control the heating member  46  to uniform temperature. Further, the protecting layer  503  may be provided on the ceramic substrate  502  of the second layer. The protecting layer  503  is formed of, for example, Si 3 N 4  or SiO 2 . 
       FIG.  13 B  is a sectional view of the heating member  46  viewed from an arrow A direction in  FIG.  13 A . As shown in  FIG.  13 B , the heat generating member  51  is formed on the ceramic substrate  501 . A method of forming the heat generating member  51  (the heat generation resistance layer) is the same as an existing method (e.g., a method of forming a thermal head). A masking layer is formed of aluminum on the heat generation resistance layer. The heat generating members adjacent to one another are insulated. The aluminum layers (the electrodes  52   a  and  52   b ) are formed in a pattern in which the heat generating members  51  are exposed in the Y direction. 
     The electric conductors  58  for wiring are connected to the aluminum layers (the electrodes  52   a  and  52   b ) at both ends of the heat generating members  51 . The electric conductors  58  are connected to, by through-hole patterns, wiring patterns  59  formed on the ceramic substrate  501  by screen printing or the like. The wiring patterns  59  are respectively joined to the switching elements of the driving ICs  53 . Therefore, power feed to the heat generating members  51  is performed from the driving source  54  via the wiring patterns  59 , the electric conductors  58 , and the switching elements of the driving ICs  53 . 
     The good heat conductors  60  are arrayed with predetermined gaps apart from one another on the ceramic substrate  502  of the second layer to compensate for the gap  56  portions among the heat generating members  51  on the ceramic substrate  501  of the first layer. Further, the protecting layer  503  is formed in a top section to cover all of the good heat conductors  60  and the like on the ceramic substrate  502  of the second layer. 
       FIG.  13 C  is a schematic sectional view of the heating member  46  viewed from the Y direction. As it is seen from  FIG.  13 C , the heat generating members  51  and the good heat conductors  60  are respectively disposed on the ceramic substrates  501  and  502  of the first layer and the second layer. The heat generating members  51  on the ceramic substrate  501  of the first layer are arrayed in the X direction of the ceramic substrate  501  with the gaps  56  having the predetermined width apart from one another. 
     The good heat conductors  60  arrayed in the second layer are arrayed with predetermined gaps apart from one another to compensate for the gaps  56  of the first layer. The end portions in the X direction of the heat generating members  51  of the first layer and the good heat conductors  60  of the second layer overlap each other. Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed such that the gaps  56  are hidden by the good heat conductors  60 . It is possible to reduce a temperature drop in the gap  56  portions by transferring the heat of the heat generating members  51  to the good heat conductors  60 . Therefore, possible to control the heating member  46  to uniform temperature. 
       FIG.  13 D  is a schematic sectional view showing another example of the heating member  46 . The heating member  46  shown in  FIG.  13 D  corresponds to the example shown in  FIG.  8   . In  FIG.  13 D , only the heat generating members  511 ,  512 ,  514 , and  516  are shown. The heat generating members  511 ,  513 ,  515 , and  517  are symmetrical to the disposition of the heat generating members  511 ,  512 ,  514 , and  516 . Illustration of the heat generating members  511 ,  513 ,  515 , and  517  is omitted. 
     In the example shown in  FIG.  13 D , the heat generating members  511 ,  512 ,  514 , and  516  on the ceramic substrate  501  of the first layer are arrayed in the X direction of the ceramic substrate  501  with the gaps  56  having the predetermined width apart from one another. The good heat conductors  60  arrayed on the ceramic substrate  502  of the second layer are arrayed to compensate for the gaps  56  of the first layer. 
     The end portions in the X direction of the heat generating members  511 ,  512 ,  514 , and  516  of the first layer and the good heat conductors  60  of the second layer overlap each other. Therefore, the heat generating members  51  are disposed in the X direction such that the gaps  56  are hidden by the good heat conductors  60 . It is possible to reduce a temperature drop in the gap  56  portions by transferring the heat of the heat generating members  51  to the good heat conductors  60 . 
     With the fixing apparatus according to the embodiment shown in  FIGS.  13 A to  13 D , in the plurality of heat generating members  51  in the heating member  46 , insulation among the heat generating members is secured. The good heat conductors  60  present in the gap  56  portions receive the heat from the heat generating members  51  and passively generate heat to reduce a temperature drop in the gap  56  portions. Therefore, possible to reduce occurrence of temperature unevenness of the heating member  46 . 
     The heat generated by the heating member  46  is diffused by a substrate, an elastic layer, a surface protecting layer, and the like of the fixing belt  41 . Therefore, the good heat conductors  60  are desirably disposed to extend across the gap  56  portions among the heat generating members  51 . 
     In the second embodiment, heat generation in a portion equivalent to an image size is explained. However, it is also possible to segment the heater and heat only a place where an image is present or heat a place where a temperature difference is partially present because of some reasons while correcting the temperature difference. 
       FIGS.  14 A to  14 D  are diagrams showing a configuration of a modification of the heating member  46  according to the second embodiment.  FIG.  14 A  is a perspective view. In the heating member  46  shown in  FIG.  14 A , the plurality of heat generating members  51  are arrayed in the X direction on the first surface (the rear surface) of a single insulating substrate (e.g., the ceramic substrate  501 ) and the good heat conductors  60  are arrayed in the X direction on the second surface (the front surface). 
     As shown in  FIG.  14 A , a heat generation resistance layer is directly stacked and formed on the rear surface of the ceramic substrate  501 . Alternatively, a glaze layer and a heat generation resistance layer are stacked and formed on the rear surface of the ceramic substrate  501 . The heat generation resistance layer configures the heat generating members  51 . The heat generating members  51  are formed of a known material such as TaSiO 2 . The heat generating members  51  are arrayed in the longitudinal direction (the X direction) with the predetermined gaps  56  apart from one another. 
     The good heat conductors  60  are arrayed with predetermined gaps apart from one another on the surface of the ceramic substrate  501  to compensate for the gap  56  portions among the heat generating members  51  formed on the rear surface. The good heat conductors  60  are metal layers of aluminum or copper. The heat generating members  51  on the rear surface of the ceramic substrate  501  and the good heat conductors  60  on the front surface are arrayed such that the end portions in the X direction overlap each other. 
     Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed in the X direction such that the gaps  56  are hidden by the good heat conductors  60 . A temperature drop in the gap  56  portions is reduced by transferring the heat of the heat generating members  51  to the good heat conductors  60 . Consequently, possible to control the heating member  46  to uniform temperature. 
     Further, the protecting layer  503  may be provided on the front surface of the ceramic substrate  501  and the protecting layer  504  may be provided on the rear surface. The protecting layers  503  and  504  are formed of, for example, Si 3 N 4  or SiO 2 . 
       FIG.  14 B  is a sectional view of the heating member  46  viewed from an arrow A direction in  FIG.  14 A . As shown in  FIG.  14 B , the heat generating member  51  is formed on the rear surface of the ceramic substrate  501 . The aluminum layers (the electrodes  52   a  and  52   b ) are formed in the Y direction of the heat generating member  51 . 
     The electric conductors  58  for wiring are connected to the electrodes  52   a  and  52   b  at both ends of the heat generating members  51 . The electric conductors  58  are connected to the wiring patterns  59  formed on the ceramic substrate  501  by screen printing or the like. The wiring patterns  59  are respectively joined to the switching elements of the driving ICs  53 . 
     In  FIGS.  14 A to  14 D , since the disposition of the heat generating members  51  and the good heat conductors  60  is mainly explained, details of the wiring patterns  59  are omitted. However, if the width in the Y direction of the ceramic substrate  501  is increased, a space for forming the wiring patterns  59  can be secured. In this way, power feed to the heat generating members  51  is performed from the driving source  54  via the wiring patterns  59 , the electric conductors  58 , and the switching elements of the driving ICs  53 . 
       FIG.  14 C  is a schematic sectional view of the heating member  46  viewed from the Y direction. As seen from  FIG.  14 C , the heat generating members  51  are disposed on the rear surface of the ceramic substrate  501  and the good heat conductors  60  are disposed on the front surface. 
     The heat generating members  51  formed on the rear surface of the ceramic substrate  501  are arrayed in the X direction of the ceramic substrate  501  with the gaps  56  having the predetermined width apart from one another. The good heat conductors  60  arrayed on the front surface of the ceramic substrate  501  are arrayed with predetermined gaps apart from one another to compensate for the gaps  56  of the heat generating members  51 . The end portions in the X direction of the heat generating members  51  on the rear surface and the good heat conductors  60  on the front surface overlap each other. 
     Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  are disposed such that the gaps  56  are hidden by the good heat conductors  60 . The good heat conductors  60  receive the heat from the heat generating members  51  and passively generate heat to reduce a temperature drop in the gap  56  portions. Consequently, possible to control the heating member  46  to uniform temperature. 
       FIG.  14 D  is a schematic sectional view showing another example of the heating member  46 . The heating member  46  shown in  FIG.  14 D  corresponds to the example shown in  FIG.  8   . In  FIG.  14 D , only the heat generating members  511 ,  512 ,  514 , and  516  are shown. The heat generating members  511 ,  513 ,  515 , and  517  are symmetrical to the disposition of the heat generating members  511 ,  512 ,  514 , and  516 . Illustration of the heat generating members  511 ,  513 ,  515 , and  517  is omitted. 
     In the example shown in  FIG.  14 D , the heat generating members  511 ,  512 ,  514 , and  516  formed on the rear surface of the ceramic substrate  501  are arrayed in the X direction of the ceramic substrate  501  with the gaps  56  having the predetermined width apart from one another. The good heat conductors  60  on the surface of the ceramic substrate  501  are arrayed to compensate for the gaps  56 . 
     The end portions in the X direction of the heat generating members  511 ,  512 ,  514 , and  516  and the good heat conductors  60  overlap each other. Therefore, the heat generating members  51  are disposed in the X direction such that the gaps  56  are hidden by the good heat conductors  60 . The good heat conductors  60  receive the heat from the heat generating members  51  and passively generate heat to reduce a temperature drop in the gap  56  portions. 
     With the fixing apparatus according to the embodiment shown in  FIGS.  14 A to  14 D , in the plurality of heat generating members in the heating member  46 , insulation among the heat generating members is secured. The good heat conductors  60  present in the gap  56  portions receive the heat from the heat generating members  51  and passively generate heat. Therefore, possible to reduce a temperature drop in the gap portions and reduce occurrence of temperature unevenness. 
     Note that the heating member  46  shown in  FIG.  14 D  corresponds to the example shown in  FIG.  8   . However, the heat generating members  511 ,  512 ,  513 , and  514  may be disposed with the gaps  56  apart from one another on the first surface (e.g., the rear surface) of the ceramic substrate  501  and the good heat conductors  60  may be alternately disposed on the second surface (e.g., the front surface) to correspond to the example shown in  FIG.  9   . 
       FIGS.  15 A and  15 B  are schematic sectional views showing another modification of the heating member  46 .  FIGS.  15 A and  15 B  area modification of the array of the heat generating members  51  of the first layer and the good heat conductors  60  of the second layer shown in  FIG.  13 C . As seen from  FIG.  15 A , the heat generating members  51  and the good heat conductors  60  are respectively disposed on the ceramic substrates  501  and  502 . The heat generating members  51  on the ceramic substrate  501  of the first layer are arrayed in the X direction of the ceramic substrate  501  with the gaps  56  having the predetermined width apart from one another. 
     The heat generating members  51  of the first layer and the good heat conductors  60  are alternately disposed in the vertical direction. The width in the X direction of the good heat conductors  60  coincides with the gaps  56  opposed thereto. 
     Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  and the good heat conductors  60  are disposed in the X direction without a gap. That is, as shown in  FIG.  10 C , the heat generating members  51  of the first layer and the good heat conductors  60  of the second layer do not overlap. However, since the gaps  56  of the first layer are compensated by the good heat conductors  60  of the second layer, it is possible to suppress a temperature drop in the gap  56  portions. 
       FIG.  15 B  is another modification of the heating member  46 . The heat generating members  51  are arrayed in the X direction with the gaps  56  having the predetermined width apart from one another on the ceramic substrate  501  of the first layer. The good heat conductors  60  of the second layer are arrayed to compensate for the gaps  56 . 
     The heat generating members  51  of the first layer and the good heat conductors  60  of the second layer are alternately disposed in the vertical direction. The end portions in the X direction do not overlap. The width in the X direction of the good heat conductors  60  is slightly smaller than the gaps  56 . 
     Therefore, if the heating member  46  is viewed from right above the figure, the heat generating members  51  and the good heat conductors  60  are disposed in the X direction with a few gaps. As shown in  FIG.  14 C , the end portions of the heat generating members  51  of the first layer and the good heat conductors  60  of the second layer do not overlap. However, since most of the gaps  56  of the first layer are compensated by the good heat conductors  60  of the second layer, there is an effect of suppressing a temperature drop of the gap  56  portions. 
     Note that the configuration in which the heat generating members  51  of the first layer and the heat generating members  51  of the second layer do not overlap can be applied to the heating member  46  shown in  FIGS.  8  and  9   . The configuration can also be applied to the heating member  46  formed on the ceramic substrate  501  having the single layer structure shown in  FIGS.  14 A to  14 D . 
       FIG.  16    is a configuration diagram showing a modification of the fixing apparatus  36  according to an embodiment. In the fixing apparatus  36  shown in  FIG.  16   , the fixing belt  41  shown in  FIG.  3    is replaced with a cylindrical endless belt  411 . The fixing apparatus  36  includes the fixing belt  411 , which is a cylindrical rotating body, and the press roller  42 . 
     A driving force is transmitted to the press roller  42  by a motor and the press roller  42  rotates. A rotating direction of the press roller  42  is indicated by an arrow t in  FIG.  16   . The fixing belt  411  rotates following the rotation of the press roller  42 . A rotating direction of the fixing belt  411  is indicated by an arrow s in  FIG.  16   . The tabular heating member  46  is provided to be opposed to the press roller  42  on the inner side of the fixing belt  411 . 
     An arcuate guide  47  is provided on the inner side of the fixing belt  411 . The fixing belt  411  is attached along the outer circumference of the guide  47 . The heating member  46  is supported by a supporting member  48  attached to the guide  47 . The heating member  46  is in contact with the inner side of the fixing belt  411  and pressed in the direction of the press roller  42 . Therefore, a fixing nip having a predetermined width is formed between the fixing belt  411  and the press roller  42 . If the sheet P passes the fixing nip, a toner image on the sheet P is fixed on the sheet P with heat and pressure. 
     That is, the fixing belt  411  revolves around the heating member  46  while being supported by the guide  47 . The heating member  46  has the basic configuration shown in  FIG.  6    or  FIGS.  8  and  9   . The heating member  46  is formed on the ceramic substrate  50  of the multilayer structure as shown in  FIGS.  10 A to  10 D  (or  FIGS.  13 A to  13 D ). Alternatively, the heating member  46  is formed on the ceramic substrate  501  having the single layer structure as shown in  FIGS.  11 A to  11 D  (or  FIGS.  14 A to  14 D ). 
     Operation during printing of the MFP  10  configured as explained above is explained with reference to a flowchart of  FIG.  17   .  FIG.  17    is a flowchart showing a specific example of control by the MFP  10  in the first embodiment. 
     First, in Act  1 , the scanner unit  15  reads image data. The CPU  100  executes an image formation control program in the imaging forming unit  20  and a fixing temperature control program in the fixing apparatus  36  in parallel. 
     If image formation processing is started, in Act  2 , the CPU  100  processes the read image data. In Act  3 , an electrostatic latent image is written on the surface of the photoconductive drum  22 . In Act  4 , the developing device  24  develops the electrostatic latent image. 
     On the other hand, if fixing temperature control processing is started, in Act  5 , the CPU  100  determines a sheet size and the size of a printing range of the image data. The determination in Act  5  is performed on the basis of, for example, a detection signal of the line sensor  40 , sheet selection information by the operation panel  14   a , or an analysis result of the image data. 
     In Act  6 , the fixing control circuit  150  selects, as a heat generation target, a heat generating member group disposed in a position corresponding to the printing range of the sheet P. For example, in the example shown in  FIG.  7   , fourteen heat generating members  51  disposed in the center to correspond to the width of the printing region are selected. 
     Subsequently, in Act  7 , the CPU  100  turns on a temperature control start signal to the selected heat generating member group. According to a start of temperature control, energization to the selected heat generating member group is performed and temperature rises. 
     Subsequently, in Act  8 , the CPU  100  detects the surface temperature of the heat generating member group with the temperature detecting member  152  disposed on the inner side or the outer side of the fixing belt  41 . Further, in Act  9 , the CPU  100  determines whether the surface temperature of the heat generating member group is within a predetermined temperature range. If determining that the surface temperature of the heat generating member group is within the predetermined temperature range (Yes in Act  9 ), the CPU  100  proceeds to Act  10 . On the other hand, if determining that the surface temperature of the heat generating member group is not within the predetermined temperature range (No in Act  9 ), the CPU  100  proceeds to Act  11 . 
     In Act  11 , the CPU  100  determines whether the surface temperature of the heat generating member group exceeds a predetermined temperature upper limit value. If determining that the surface temperature of the heat generating member group exceeds the predetermined temperature upper limit value (Yes in Act  11 ), in Act  12 , the CPU  100  turns off energization to the heat generating member group selected in Act  6  and returns to Act  8 . 
     If determining that the surface temperature of the heat generating member group does not exceed the predetermined temperature upper limit value (No in Act  11 ), the surface temperature is lower than a predetermined temperature lower limit value according to the determination result in Act  9 . Therefore, in Act  13 , the CPU  100  maintains the energization to the heat generating member group in the ON state or turns on the energization again and returns to Act  8 . 
     Subsequently, in Act  10 , the CPU  100  conveys the sheet P to a transfer section a state in which the surface temperature of the heat generating member group is within the predetermined temperature range. In Act  14 , the CPU  100  transfers a toner image onto the sheet P. After transferring the toner image onto the sheet P, the CPU  100  conveys the sheet P into the fixing apparatus  36 . 
     Subsequently, in Act  15 , the fixing apparatus  36  fixes the toner image on the sheet P. In Act  16 , the CPU  100  determines whether to end the print processing of the image data. If determining to end the print processing (Yes in Act  16 ), in Act  17 , the CPU  100  turns off the energization to all the heat generating member groups and ends the processing. On the other hand, if determining not to end the print processing of the image data yet (No in Act  16 ), the CPU  100  returns to Act  1 . That is, if printing target image data remains, the CPU  100  returns to Act  1  and repeats the same processing until the processing ends. 
     As explained above, in the fixing apparatus  36  according to the embodiment, the heat generating member group of the heating member  46  (the heater) is disposed in the direction (the X direction) orthogonal to the sheet conveying direction Y. The heating member  46  is disposed in contact with the inner side of the fixing belt  41 . Any one of the heat generating member groups is selectively energized to correspond to a printing range (an image forming region) of image data. Therefore, possible to prevent abnormal heat generation of a non-paper passing portion of the sheet of the heating member  46  and suppress useless heating of the non-paper passing portion. Therefore, possible to greatly reduce thermal energy. 
     Even if the heat generating members of the heating member  46  are disposed with predetermined gaps apart from one another, it is possible to suppress a temperature drop in the gap portions and equalize temperature with heat generation members complementarily disposed in multiple layers and a good heat conductor layer. Therefore, possible to improve fixing quality. 
     Note that the formation of the heat generation resistance layer and the good heat conductor layer on the ceramic substrate  50  and the formation of the wiring patterns can also be configured by an LTCC (Low Temperature Co-fired ceramics) multilayer substrate. The LTCC multilayer substrate is known as a low-temperature baked stacked ceramics substrate formed by simultaneously baking a wiring conductor and a ceramics substrate at low temperature of, for example, 900° C. or less. Also possible to realize the LTCC multilayer structure by forming a layer of a heat-resistant insulating body through various film formation (thin film and thick film) processes. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the invention. Indeed, the novel apparatus described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the apparatus described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.