Patent Publication Number: US-7917073-B2

Title: Sliding member and fixing device, and image forming apparatus using the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 USC 119 from Japanese Patent Application No. 2007-244301 filed on Sep. 20, 2007. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a sliding member and a fixing device, and an image forming apparatus using the sliding member or the fixing device. 
     2. Description of the Related Art 
     Various fixing devices have been proposed recently that use a belt, instead of conventional fixing devices that use rolls, with the aim of achieving high manufacturability and increasing the ease-of-use by shortening the warm up time of heating members and the like. 
     SUMMARY OF THE INVENTION 
     The present invention provides a sliding member that may effectively prevent cracking and delamination of a diamond-like carbon layer. 
     Further provided is a fixing device that may maintain superior abrasion resistance and sliding properties over a prolonged period of time, and an image forming apparatus that may provide superior images over a prolonged period of time. 
     According to a first exemplary embodiment of a first aspect of the invention, there is provided a sliding member comprising: 
     a substrate; and 
     a non-continuous diamond-like carbon layer provided on a surface of the substrate, the non-continuous diamond-like carbon layer being formed from a plurality of diamond-like carbon layer portions that are separated from one another by grooves. 
     According to a first exemplary embodiment of a second aspect of the invention, there is provided a fixing device comprising: 
     a fixing belt; 
     a pressure member that contacts the outer peripheral surface of the fixing belt; and 
     at least one fixed sliding member on which the fixing belt slides, the fixed sliding member contacting the inner peripheral surface of the fixing belt, at least one of the fixing belt and the fixed sliding member comprising a non-continuous diamond-like carbon layer on a sliding surface between the fixing belt and the fixed sliding member, the non-continuous diamond-like carbon layer being formed from a plurality of diamond-like carbon layer portions that are separated from one another by grooves. 
     According to a first exemplary embodiment of a third aspect of the invention, there is provided an image forming apparatus, comprising a sliding member including: a substrate; and a non-continuous diamond-like carbon layer provided on a surface of the substrate, the non-continuous diamond-like carbon layer being formed from a plurality of diamond-like carbon layer portions that are separated from one another by grooves. 
     According to a first exemplary embodiment of a fourth aspect of the invention, there is provided an image forming apparatus comprising a fixing device including: 
     a fixing belt; 
     a pressure member that contacts the outer peripheral surface of the fixing belt; and 
     at least one fixed sliding member on which the fixing belt slides, the fixed sliding member contacting the inner peripheral surface of the fixing belt, 
     at least one of the fixing belt and the fixed sliding member comprising a non-continuous diamond-like carbon layer on a sliding surface between the fixing belt and the fixed sliding member, the non-continuous diamond-like carbon layer being formed from a plurality of diamond-like carbon layer portions that are separated from one another by grooves. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a schematic configuration diagram showing an image forming apparatus according to a first exemplary embodiment of the invention; 
         FIG. 2  is a schematic cross-section showing a fixing device according to the first exemplary embodiment; 
         FIG. 3  is a different schematic cross-section showing a fixing device according to the first exemplary embodiment; 
         FIG. 4A  is a schematic cross-section showing the surface of a fixing belt using conventional technology, and  FIG. 4B  is a schematic cross-section showing the surface of a fixing belt of the first exemplary embodiment; 
         FIG. 5  is a schematic plan view showing a fixing belt according to the first exemplary embodiment; 
         FIG. 6  is a schematic cross-section showing the surface of a fixed sliding member according to a second exemplary embodiment of the invention; 
         FIG. 7  is a schematic cross-section showing the surface of a fixed sliding member according to a third exemplary embodiment of the invention; and 
         FIG. 8  is a graph showing the results of drive torque measurement in Examples of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention provides a sliding member, including: 
     a substrate; and 
     a non-continuous diamond-like carbon layer provided on a surface of the substrate, the non-continuous diamond-like carbon layer being formed from a plurality of diamond-like carbon layer portions that are separated from one another by grooves. 
     Specific examples of the sliding member include a belt for image formation, a fixing belt, and a fixed sliding member for an image forming apparatus. 
     Explanation will now be given of exemplary embodiments of the present invention with reference to the drawings. It should be noted that members with the same function are appended with the same reference numerals throughout the drawings, and duplicated explanation thereof may be omitted. 
     First Exemplary Embodiment 
       FIG. 1  is a schematic configuration diagram showing an image forming apparatus according to a first exemplary embodiment of the invention.  FIG. 2  is a schematic cross-section showing a fixing device according to the first exemplary embodiment.  FIG. 3  is a different schematic cross-section showing a fixing device according to the first exemplary embodiment.  FIG. 4A  is a schematic cross-section showing the surface of a fixing belt with conventional technology.  FIG. 4B  is a schematic cross-section showing the surface of a fixing belt which is a sliding member of the first exemplary embodiment.  FIG. 5  is a schematic plan view showing a fixing belt according to the first exemplary embodiment. 
     A schematic cross-section of the fixing device is shown in  FIG. 2 , looking along the axial direction of the fixing device.  FIG. 3  is a schematic cross-section of a fixing device, and is a schematic cross-section taken on  2 - 2  of  FIG. 2  shown looking along a direction that is orthogonal to the axial direction of the fixing device.  FIG. 4A  and  FIG. 4B  are schematic cross-sections of fixing belts showing surface profiles thereof.  FIG. 5  is a schematic plan view of a fixing belt seen from the direction of arrow G in  FIG. 4B  (the inner peripheral surface of the fixing belt seen from a direction that is orthogonal to the fixing belt axial direction). 
     An image forming apparatus  100  according to the first exemplary embodiment, as shown in  FIG. 1 , is provided with a circular cylinder-shaped photoreceptor drum  10  that rotates in one direction (shown as the direction of arrow A in  FIG. 1 ). Around the periphery of the photoreceptor drum  10  there are provided, in sequence from the upstream side in the rotation direction of the photoreceptor drum  10 : a charging device  12  for charging the surface of the photoreceptor drum  10 ; an exposure device  14  for irradiating image light L onto the photoreceptor drum  10  to form latent images on the surface of the photoreceptor drum  10 ; a developing device  16  including developers  16 A to  16 D for selectively transferring toner onto the latent images on the photoreceptor drum  10  surface to form toner images; an intermediate transfer member  18  that is of an endless belt shape, supported so as to face the photoreceptor drum  10  and so that the peripheral surface of the intermediate transfer member  18  is able to rotate; a cleaning device  20  for removing any toner remaining on the photoreceptor drum  10  after the toner images have been transferred onto the intermediate transfer member  18 ; and a charge removing light exposing device  22  for removing remaining charge on the surface of the photoreceptor drum  10 . 
     Furthermore, there are, disposed at the inside of the intermediate transfer member  18 , a primary transfer device  24  for primary transferring the toner image that has been formed on the surface of the photoreceptor drum  10  to the intermediate transfer member  18 , two support rolls  26 A and  26 B, and a transfer counter roll  28  for carrying out secondary transfer. The intermediate transfer member  18  is entrained around the primary transfer device  24 , the support rolls  26 A and  26 B, and the transfer counter roll  28  so as to be able to rotate in one direction (shown as the direction of arrow B in  FIG. 1 ). There is a transfer roll  30  provided facing the transfer counter roll  28  with the intermediate transfer member  18  therebetween, the transfer roll  30  carrying out secondary transfer of the toner images, which been primary transferred to the outer peripheral surface of the intermediate transfer member  18 , onto a sheet of recording paper (a recording medium) P, with a press-contact portion between the transfer counter roll  28  and the transfer roll  30  such that the sheet of recording paper P is fed in, in the direction of arrow C. The toner image is secondary transferred onto the surface of the recording paper P at the press-contact portion and the recording paper P is conveyed in the direction of arrow C. 
     On the downstream side of the transfer roll  30  in a direction in which the sheet of recording paper P is conveyed (i.e., a direction of arrow C), there is provided a fixing device  32  for thermally fusing the toner image transferred onto the surface of the recording sheet of paper P to fix it on the recording sheet of paper P. The sheet of recording paper P having the toner image is fed into the fixing device  32  via a paper guide member  36 . Around the intermediate transfer member  18 , a cleaning device  34  for removing the toner remaining on the surface of the intermediate transfer member  18  is provided downstream in the rotation direction of the intermediate transfer member  18  (i.e., a direction of arrow B). 
     Explanation will now be given of a fixing device according to the first exemplary embodiment. 
     As shown in  FIG. 2  and  FIG. 3 , a fixing device  32  according to the first exemplary embodiment is provided with: a fixing belt  38  that is of an endless belt shape and that rotates in one direction (the direction of arrow D); a pressure roll  40  that press contacts with the outer peripheral surface of the fixing belt  38  and that rotates in one direction (the direction of arrow E); and a magnetic field generation device  42  that is disposed facing, but at a distance from, the outer peripheral surface of the fixing belt  38  at the opposite side thereof to the side of the press-contact surface of the pressure roll  40 . 
     At the inner peripheral side of the fixing belt  38  there are provided: a fixed sliding member  44  that forms a contact portion with the pressure roll  40 ; a heat generation control member  46  that is disposed facing the magnetic field generation device  42  with the fixing belt  38  therebetween, the heat generation control member  46  being disposed in contact with the inner peripheral surface of the fixing belt  38 ; and a support member  48  for supporting the fixed sliding member  44 . The heat generation control member  46  is also supported by the support member  48 . There are driving force transmission members  50  provided at the two edge portions of the fixing belt  38 , for imparting rotational driving force to the fixing belt  38  for rotational driving the fixing belt. 
     There is also a separating member  52  provided to the downstream side in the recording paper P conveying direction (direction of arrow F) of the contact portion between the fixing belt  38  and the pressure roll  40 . The separating member  52  is formed with a support portion  52 A that is fixed and supported at one end thereof, and a separation sheet  52 B that is supported by the support portion  52 A. The leading edge of the separation sheet  52 B is disposed so as to be in the vicinity of, or in contact with, the fixing belt  38 . 
     Explanation will first be given of the fixing belt  38 . The fixing belt  38  is provided with a belt substrate  62  and a non-continuous diamond-like carbon (DLC) layer  64  that is provided on the surface (inner peripheral surface) of the belt substrate  62 , as shown in  FIG. 4B . 
     The belt substrate  62  is a heat generation layer that generates heat under the action of a magnetic field (magnetic flux), and the belt substrate  62  may be formed from a material that readily allows a magnetic field (magnetic flux) to pass through and readily generates heat by the action of such a magnetic field, with a low heat capacity. Specific examples of the heat generation layer include, for example, heat generation layers that include a non-magnetic metal material and are of a thickness of equal to or about 1 μm to equal to or about 20 μm, with equal to or about 2 μm to equal to or about 15 μm being preferable. Examples of the non-magnetic metal material include, for example, metals such as copper, aluminum or silver. 
     The non-continuous DLC layer  64  of the invention is different from the continuous DLC layer  64 A shown in  FIG. 4A , and as shown in  FIG. 4B , in the non-continuous DLC layer  64  of the invention there are plural DLC layer portions  64 B formed in a non-continuous film on the surface of the belt substrate  62 , so as to be separate from each other. The thickness of the non-continuous DLC layer  64  is, for example, equal to or about 0.01 μm to equal to or about 5 μm, with equal to or about 1 μm to equal to or about 5 μm being preferable. 
     Furthermore, the plural DLC layer portions  64 B are separated from each other by grooves  66 , and, as shown in  FIG. 5 , the grooves  66  are formed at an angle that is toward the belt axial direction central portion when facing from the downstream side back toward the upstream side in the sliding direction (direction of arrow H) relative to the fixed sliding member  44 . In other words, in reference to  FIG. 5 , the grooves  66  are formed symmetrically from the belt axial direction central portion to the respective left and right sides of the belt, and the grooves  66  that are formed in the region to the right side of the belt axial direction central portion are formed slanting at an angle up to the left from the axial direction portion edge of the right side region, while the grooves  66  that are formed in the region to the left side of the belt axial direction central portion are formed slanting at an angle up to the right from the axial direction portion edge of the left side region. 
     It should be noted that the length of each side of the plural DLC layer portions  64 B shown above (that is to say the length of each side when the plural DLC layer portions  64 B that have been formed on the belt inner peripheral surface are viewed from the belt radial direction) is formed to be equal to or about 10 μm to equal to or about 3 mm, with equal to or about 10 μm to equal to or about 100 μm being preferable. Furthermore, the width of the grooves  66  is formed to be equal to or about 1 μm to equal to or about 100 μm, with equal to or about 1 μm to equal to or about 10 μm being preferable. 
     Explanation will now be given of the diamond-like carbon (DLC) used in the plural DLC layer portions  64 B. The structure and other properties relating to materials formed from carbon atoms, that is diamond, DLC, and graphite, are shown in Table 1. DLC is a material formed from carbon atoms, and is composed of an amorphous structure including both diamond structures and graphite structures, with partial hydrogenation thereof (part of which including bonds with hydrogen atoms). DLC therefore possesses properties that are intermediate to those of diamond and graphite. 
     Furthermore, a ta-C (Tetrahedral Amorphous Carbon) form of DLC is particularly preferably used from the standpoint of its high hardness and low abrasion coefficient. ta-C refers to a material formed from carbon atoms with an amorphous structure, wherein equal to or about 85% or more of bonding within the structure is sp3 bonding. 
     Table 1 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 DLC 
                   
               
               
                   
                 DIAMOND 
                 (Diamond Like Carbon) 
                 GRAPHITE 
               
               
                   
               
             
            
               
                 STRUC- TURE 
                 
                   
                     
                     
                         
                         
                     
                   
                 
                 
                   
                     
                     
                         
                         
                     
                   
                 
                 
                   
                     
                     
                         
                         
                     
                   
                 
               
               
                   
               
               
                 CONSTI- 
                 C 
                 C•H 
                 C 
               
               
                 TUTIVE 
               
               
                 ELEMENT 
               
               
                 PROCESS 
                 Plasma-Assisted Chemical 
                 Plasma-Assisted CVD 
                 CVD 
               
               
                   
                 Vapor Deposition(CVD) 
                 Ion Plating etc. 
                 (Equilibrium Plasma) 
               
               
                   
                 (Nonequilibrium Plasma) 
                 (Nonequilibrium Plasma) 
               
               
                 REACTIVE 
                 CnHm and H 2   
                 CnHm or C Vapor 
                 CnHm 
               
               
                 GAS 
                 CH 4 :H 2  = 1:100 
                 CH 4 , C 2 H 2 , C 6 H 6 , etc. 
                 CnHm 
               
               
                 PROCESS- 
                 ~700° C. 
                 RT~300° C. 
                 &gt;1500° C. 
               
               
                 ING 
               
               
                 TEMPER- 
               
               
                 ATURE 
               
               
                   
               
            
           
         
       
     
     There are no particular limitations to the method of forming the plural DLC layer portions  64 B, but they may be formed, for example, by a plasma-chemical vapor deposition method or by a cathodic arc method. The thickness of the plural DLC layer portions  64 B is preferably equal to or about 0.5 μm to equal to or about 5 μm. 
     A ta-C layer may be formed as the plural DLC layer portions  64 B by, for example, extracting C +  from carbon (graphite) using electric arc discharge, and forming a film. Such a method is referred to as a cathodic arc method, and DLC layers with particular characteristics that have been formed by such methods are described, for example, in the publication International Conference on Micromechatronics for Information and Precision Equipment (Tokyo, Jul. 20-23, 1997) pp. 357 to 362. Such DLC layers have a relatively large number of sp3 bonds in comparison to DLC layers formed as films using reactive sputtering methods, Electron Cyclotron Resonance—Chemical Vapor Deposition (ECR-CVD) methods, and the like, and such DLC layers have the properties of hardness and a low abrasion coefficient, when used as coating materials. 
     Masking of the belt substrate  62  with predetermined shapes, in advance of application of the DLC, may be included in the method for forming the plural DLC layer portions  64 B. In such a method the shape of the plural DLC layer portions  64 B in the non-continuous DLC layer  64  may be freely designed. 
     The configuration of the fixing belt  38  is not limited to the configuration described above, and belts may be used in which, as a belt substrate  62 , a heat generation layer is provided on the surface of a substrate layer, with a DLC layer formed on the inner peripheral surface thereof (surface of the substrate layer), and belts may be used that have a heat generation layer provided on such a substrate layer, but with an elastic layer therebetween. 
     It should be noted that the substrate layer is preferably formed from a material selected from materials which are strong enough for supporting the heat generation layer, are heat-resistant, and do not generate heat, or hardly generate heat, due to the action of a magnetic field while allowing the magnetic field to pass therethrough. For example, a metal belt may be used that is formed of a metal material, such as non-magnetic metals such as non-magnetic stainless-steel, soft magnetic materials and hard magnetic materials such as Fe, Ni, Co, or alloys thereof (such as Fe—Ni—Co alloys and Fe—Cr—Co alloys), and the like, or a resin belt may be used that is formed of a resin such as polyimide. In addition, the elastic layer may include silicone rubber, fluorine rubber, fluorosilicone rubber, or the like. 
     The radius of the fixing belt  38  is, for example, suitably about 20 mm to about 50 mm. A lubricant (such as silicone oil, for example) may be applied to the inner peripheral surface of the fixing belt  38  that has been formed with the plural DLC layer portions  64 B (the sliding surface against the fixed sliding member  44 ). 
     Explanation will next be given of the pressure roll  40 . An example is described below of the first exemplary embodiment in which the pressure roll  40  is separable from the fixing belt  38 . However, the fixing belt  38  and the pressure roll  40  may be in constant contact. The pressure roll  40  is disposed, for example, with spring members (not shown) at each end thereof, so as to press the fixed sliding member  44 , through the fixing belt  38  with a total load of equal to or about 294 N (equal to or about 30 kgf). However, upon pre-heating (heating up to the state in which fixing is possible) the pressure roll  40  is moved (not shown) so as to be separated from the fixing belt  38 . 
     As the pressure roll  40 , for example, a roll including a cylindrical core member  40 A made of a metal and an elastic layer  40 B (e.g., a silicone rubber layer, a fluororubber layer) provided on the surface of the core member  40 A can be used. If necessary, the pressure roll  40  may have a surface release layer (e.g., a fluoroplastic layer) on the outermost surface thereof. 
     Explanation will next be given of the heat generation control member  46 . The heat generation control member  46  is configured in a shape that is similar to the inner peripheral surface of the fixing belt  38 , and is disposed so as to contact the inner peripheral surface of the fixing belt  38 , and so as also to face the magnetic field generation device  42  with the fixing belt  38  therebetween. 
     Furthermore, the heat generation control member  46  is held, through spring members  48 B of the support member  48 , in a non-contact state to the support member body  48 A and the heat generation control member  46  maintains the fixing belt  38  in a circular cylindrical shape while disposed in contact with the inner peripheral surface of the fixing belt  38  without applying thereto pressure. In the first exemplary embodiment the heat generation control member  46  contacts the inner peripheral surface of the fixing belt  38  with a force of equal to or about I N. There is no extreme distortion of the belt shape when the heat generation control member  46  contacts with the belt, since a tensional force is not applied to the belt. 
     The heat generation control member  46  may, for example, be composed of a temperature-sensitive magnetic metal material having a Curie point, and includes a non-heat generating body that does not generate heat by the action of a magnetic field thereon. The Curie point of the temperature-sensitive magnetic metal material is preferably in a range of a preset temperature of the fixing belt  38  to a heat-resistant temperature of the fixing belt  38 . More specifically, the Curie point is preferably in a range of, for example, equal to or about 140° C. to equal to or about 240° C., more preferably in a range of equal to or about 150 to equal to or about 230° C. 
     Explanation will next be given of the fixed sliding member  44 . The fixed sliding member  44  may, for example, be composed of a rod shaped member with an axial line along the axial direction (width direction) of the fixing belt  38 , and is a member that resists the pressure acting from the pressure roll  40 . The fixing belt  38  is deformed to the inner peripheral surface side thereof, by pressure from the pressure roll  40  pressing the fixed sliding member  44  through the fixing belt  38 . In this manner, curvature is applied to the fixing belt  38  at the downstream side portion in the paper conveying direction of the contact portion between the pressure roll  40  and the fixed sliding member  44 , and the paper is thereby separated from the fixing belt  38 . 
     In order to obtain the above separating effect of the paper, the configuration of the fixing belt  38  is determined depending on whether the fixing belt  38  is able to elastically deform toward the inner peripheral side thereof by the pressing of the pressure roll  40  to the fixed sliding member  44  through the fixing belt  38 . In the first exemplary embodiment a metal material is used for the fixing belt  38 . Therefore the flexibility of the fixing belt is determined by the layer of the metal, which determines the rigidity of the fixing belt  38 . 
     It may be examined by use of a non-magnetic stainless hard material whether or not the fixing belt  38  warps or bends toward the inside thereof inside its elastic deformation region. When a pressing force equal to or more than the load imposed onto the fixing belt at least at the time of the fixation of an image is given thereto, the warp amount thereof is evaluated. As a result, when the thickness of the hard material is 250 μm, the material hardly warps. When the thickness is 200 μm, the generation of a slight warp begins. When the thickness is 150 μm, 125 μm, 100 μm, and 75 μm, a sufficient warp is generated. Accordingly, the metal material layer of the fixing belt  38  is desirably 200 μm or less. 
     There are no particular limitations to the material of the fixed sliding member  44 , as long as the warp amount is below a certain amount when the pressing force of the pressure roll  40  acts thereon. Silicone rubber, for example, may be appropriately used. Other than silicone rubber, heat resistant resins, such as aluminum or glass fiber reinforced PPS (polyphenylene sulfite), phenol, polyimide, or liquid crystal polymers, may be used. 
     Explanation will next be given of the support member  48 . The support member  48  is, for example, configured with: a support member body  48 A; spring members  48 B for supporting the heat generation control member  46 ; and shafts  48 C that are provided at both ends, in the length direction of the support member body  48 A, of the support member body  48 A. 
     The support member body  48 A and the shafts  48 C may, for example, be made from a metal material or from a resin material or the like, and the support member body  48 A may be composed, for example, of a non-magnetic metal material (for example copper, aluminum or silver). If the warp due to the load on the shafts  48 C is large and the shaft rigidity is a problem, then the shafts  48 C may be constructed from a material having a Young&#39;s modulus such that the warp is small, together with a non-magnetic material. 
     The spring members  48 B are connecting members between the heat generation control member  46  and the support member body  48 A, and directly support the heat generation control member  46 . The spring members  48 B are connected to the heat generation control member  46  at both ends in the width direction of the heat generation control member  46 . 
     The spring members  48 B are, for example, configured as bent plate springs (made, for example, from a metal, or from various elastomers). The heat generation control member  46  is supported by these spring members  48 B, and also follows displacement of the fixing belt  38 , even if the fixing belt  38  rotates eccentrically and the fixing belt  38  is displaced in the radial direction thereof, so as to maintain a contact state with the inner peripheral surface of the fixing belt  38 . 
     Explanation will next be given of the driving force transmission members  50 . The driving force transmission members  50  are each a member for transmitting driving force for rotating the fixing belt  38  around its rotary center. The members  50  are each composed of, for example, a flange section  50 A fitted to the inside of one of ends of the fixing belt  38  and a cylindrical gear section  50 B having, in its outer peripheral surface, irregularities. The driving force transmission members  50  are composed of, for example, a metal material, a resin material, or the like. 
     The driving force transmission members  50  are disposed at the edge portions of the fixing belt  38  while the flange portions  50 A of the driving force transmission members  50  are fitted inside each of the edges of the fixing belt  38 . The gear portions  50 B of the driving force transmission members  50  are rotationally driven by a motor or the like (not shown), and this rotational force is transmitted to the fixing belt  38 , and the fixing belt  38  itself rotates. 
     The driving force transmission members  50  are fitted to both ends of the fixing belt  38  in its axial direction. However, the invention is not limited to this form. A driving force transmission member may be fitted only to one end of the fixing belt  38  in its axial direction. The driving force transmission members  50  are supported at the ends of the fixing belt  38  by fitting the flange sections  50 A to the insides of the ends of the fixing belt  38 . However, the invention is not limited to this form. The driving force transmission members  50  may be supported at the ends of the fixing belt  38  by fitting ends of the fixing belt  38  to the insides of the flange sections  50 A. 
     Explanation will next be given of the magnetic field generation device  42 . The magnetic field generation device  42  is formed to have a shape following the outer peripheral surface of the fixing belt  38 . The magnetic field generation device  42  is arranged so as to face the heat generation control member  46  through the fixing belt  38  between the device  42  and the member  46 , and separately from the outer peripheral surface of the fixing belt  38  to have an interval of, for example, equal to or about 1 mm to equal to or about 3 mm. In the magnetic field generation device  42 , an exciting coil (magnetic field generation unit)  42 A wound into plural circles is arranged along the axial direction of the fixing belt  38 . 
     To this exciting coil  42 A is connected an exciting circuit (not shown) for supplying an alternating current to the exciting coil  42 A. Moreover, a magnetic substance member  42 B is arranged to extend along the length direction of the exciting coil  42 A (the axial direction of the fixing belt  38 ) on the surface of the coil  42 A. 
     Due to the output of the magnetic field generation device  42 , for example, a magnetic field (magnetic flux) passes through the heat generation layer of the fixing belt  38  and causes the heat generation layer to heat up. 
     It should be noted that the magnetic field generation device  42  may be provided at the inner peripheral surface side of the fixing belt  38  with a predetermined gap thereto. In such a case, the heat generation control member  46  is provided in contact with the outer peripheral surface of the fixing belt  38 . 
     Explanation will now be given of the operation of the image forming apparatus  100  according to the first exemplary embodiment. 
     First, the surface of the photoreceptor drum  10  is charged by the charging device  12 . Next, from the exposure device  14 , the light L is imagewise radiated to the surface of the photoreceptor drum  10  so that a latent image is formed on the surface by a difference between electrostatic potentials on the surface. The photoreceptor drum  10  is rotated in the direction of the arrow A so that the latent image is transferred to a position opposite to one (the developer  16 A) out of the developers of the developing device  16 . A first color toner is then transferred from the developer  16 A onto the latent image so that a toner image is formed on the surface of the photoreceptor drum  10 . By the rotation of the photoreceptor drum  10  in the direction of the arrow A, this toner image is transported to a position opposite to the intermediate transferring member  18 , and then the image is electrostatically transferred primarily onto the surface of the intermediate transferring member  18  by the transfer device  24 . 
     Toner remaining on the surface of the photoreceptor drum  10  after primary transfer is removed by the cleaning device  20 , and the surface of the cleaning device  20  after cleaning is initialized to the initial voltage by the charge removing light exposing device  22 , and then the surface is moved to a position which again faces the charging device  12 . 
     The three developers  16 B,  16 C and  16 D of the developing device  16  then move so as to sequentially be positioned facing the photoreceptor drum  10 . The toner images of the second color, third color and fourth color are formed in succession with the same method as used for the first color, and these toner images are each primary transferred onto the surface of the intermediate transfer member  18  so as to be superimposed as four colors. 
     The toner images that have been superimposed on top of each other on the intermediate transfer member  18  are moved by the rotational movement of the intermediate transfer member  18  in the direction of arrow B, and conveyed to the position between the transfer roll  30  and the transfer counter roll  28 , and the toner images contact with the recording paper P that has been conveyed in. A transfer bias voltage is applied between the transfer roll  30  and the intermediate transfer member  18 , and the toner images are secondary transferred onto the surface of the recording paper P. 
     The recording paper P holding the toner images, which have not yet been fixed, is carried via a paper guide member  36  to the fixing device  32 . 
     The operation of the fixing device  32  according to the first exemplary embodiment will next be explained. 
     First, in the fixing device  32 , for example, the toner image forming operation in the image forming apparatus  100  is initiated, and at the same time (there may, of course, be a time lag, and this also applies to other cases below), with the fixing belt  38  and the pressure roll  40  in a separated state, the driving force transmission members  50  are rotationally driven by a motor (not shown), and the fixing belt  38  is rotationally driven therewith in the direction of arrow D at, for example, a peripheral speed of equal to or about 200 mm/s. 
     Together with the rotational driving of the fixing belt  38 , an alternating current is supplied from an excitation circuit (not shown) to an exciting coil  42 A included in the magnetic field generation device  42 . When the alternating current is supplied to the exciting coil  42 A, magnetic flux (magnetic field) is repeatedly generated and extinguished in the periphery of the exciting coil  42 A. When this magnetic flux (magnetic field) cuts across the heat generation layer of the fixing belt  38 , an eddy current is generated in the heat generation layer, which generates a magnetic field that opposes the change in the initial magnetic field, and heat is generated in proportion to the surface resistance of the heat generation layer and the square of the current flowing in the heat generation layer. 
     The fixing belt  38  is thereby heated by the heat generation layer up to a predetermined temperature (150° C., for example) for equal to or about 10 seconds, for example. 
     Next, in a state in which the pressure roll  40  is pressed against the fixing belt  38 , the recording paper P that has been conveyed into the fixing device is conveyed into the contact portion between the fixing belt  38  and the pressure roll  40 , and the recording paper P pressed and heated by the fixing belt  38  that has been heated by the heat generation layer and the pressure roll  40 , the toner image is fused and press-adhered to the surface of the recording paper P, and the toner image is fixed to the surface of the recording paper P. 
     The plural DLC layer portions  64 B that are formed on the inner peripheral surface of the fixing belt  38  are of a material that is extremely hard and brittle. If the DLC layer was to be made in the manner of the continuous layer DLC layer  64 A as shown in  FIG. 4A , then when force is applied to the belt substrate  62 , such as by the driving of the fixing belt  38  and the sliding movement against the fixed sliding member  44 , then cracking and delamination of the DLC layer  64 A would occur. As a result, a reduction in the abrasion resistance and ability to slide of the DLC occurs, with a reduction in reliability. 
     In contrast, by making the DLC layer  64  as a non-continuous layer (a layer formed from plural DLC layer portions  64 B that have been formed to be separate from each other), concentrations of stress due to warping of the DLC may be prevented from occurring, and the occurrence of cracks and delamination in the DLC layer  64  may be suitably prevented. 
     Furthermore, the plural DLC layer portions  64 B are separated from each other with the grooves  66  therebetween, and the grooves  66  are formed at an angle that is toward the belt axial direction central portion when facing from the downstream side back to the upstream side in the sliding direction (direction of arrow H) relative to the fixed sliding member  44 . Therefore, a lubricant flows toward the belt axial direction central portion during sliding against the fixed sliding member  44 , and uneven distribution of the lubricant toward the two edge portions, and leakage of the lubricant, may furthermore be suitably prevented, so that good sliding characteristics may be maintained over a prolonged period. 
     When fixing is carried out with the fixing belt  38  and the pressure roll  40 , the fixing belt  38  is contacted without pressure to the heat generation control member  46  that has a shape that is similar to that of the inner peripheral surface of the fixing belt  38 . Thereby: the fixing belt  38  rotates while being supported; a reduction in the sliding resistance is suppressed: vibrations of the fixing belt  38  due to the fixed sliding member  44  are suppressed, and electromagnetic force (the repulsion force between the magnetic field from the coil and the reaction magnetic field opposing the coil magnetic field formed by eddy currents flowing in the heat generation layer, that is to say the force acting on the belt from the coil in a direction to force them apart) is taken by the heat generation control member  46 ; and fixing takes place with a stable separation distance between the belt and the coil, with the belt shape maintained. 
     When the recording paper P is transferred from the contact portion between the fixing belt  38  and the pressure roll  40 , the recording paper P attempts to carry straight on in the direction in which it has been conveyed out due to its rigidity, and the leading edge of the recording paper P is thereby separated from the curve of the rotating fixing belt  38 . Then, the separating member  52  (separation sheet  52 B) intrudes into the gap between the leading edge of the recording paper P and the fixing belt  38 , and the recording paper P is separated from the fixing belt  38 . 
     As described above, the toner image is formed on the recording paper P and then fixed thereon. 
     Furthermore, the first exemplary embodiment shows a belt on which the non-continuous DLC layer  64  is formed from the plural DLC layer portions  64 B, which is used as the fixing belt, but there is no limitation thereto. The belt formed with the non-continuous DLC layer  64  may be used, for example, as an intermediate transfer belt, a recording medium conveying belt, or the like. 
     Second Exemplary Embodiment 
     An image forming apparatus according to a second exemplary embodiment of the invention is the same as the image forming apparatus according to the first exemplary embodiment except that it has a non-continuous DLC layer formed on a sliding surface of the fixed sliding member  44  in the fixing device  32 , instead of having the plural DLC layer portions  64 B formed on the surface of the belt substrate  62  of the fixing belt  38  as in the image forming apparatus according to the first exemplary embodiment. The term sliding surface refers here to a surface of the fixed sliding member  44  on/against which another member slides, and in the second exemplary embodiment refers to the surface of the fixed sliding member  44  on which the fixing belt  38  slides. 
     The same configuration as that in the image forming apparatus according to the first exemplary embodiment may be used, as it is, in the image forming apparatus according to the second exemplary embodiment, apart from the different characteristics mentioned above. Therefore, these characteristics will now be explained, and explanation of the rest of the configuration will be omitted. 
       FIG. 6  is a schematic cross-section showing the surface (sliding surface) of a fixed sliding member according to the second exemplary embodiment 
     In the image forming apparatus according to the second exemplary embodiment there is no non-continuous DLC layer  64  formed on the surface of the fixing belt  38 , as described above, that is to say the belt substrate  62  alone configures the fixing belt  38 . Furthermore, as shown in  FIG. 6 , in the fixed sliding member  244  of the second exemplary embodiment there is a non-continuous DLC layer  264  formed from plural DLC layer portions  264 B on the surface (sliding surface) of a substrate  262 . The plural DLC layer portions  264 B are furthermore separated from each other by grooves  266 , and the grooves  266 , in the same manner as the grooves  66  of the first exemplary embodiment, are formed at an angle that is toward the belt axial direction central portion direction when facing in the sliding direction (the direction that the fixing belt  38  slides) from the upstream side toward the downstream side. The same materials may be used for the substrate  262  of the fixed sliding member  244  as are used in the fixed sliding member  44  of the first exemplary embodiment. 
     Forming the non-continuous DLC layer  264  on the surface (sliding surface) of the fixed sliding member  244  may be undertaken by the same methods as are used for forming the non-continuous DLC layer  64  in the first exemplary embodiment. 
     The DLC for forming the DLC layer portions  264 B provided on the sliding surface of the fixed sliding member  244  is a material that is extremely hard and brittle, and conventionally there would be concern that cracking and delamination of a DLC layer might occur if force is applied to the substrate. However, in contrast, by using the configuration of the non-continuous DLC layer  264  formed from the plural DLC layer portions  264 B that have been formed so as to be separate from each other, concentrations of stress due to warping of the DLC may be prevented from occurring, and the occurrence of cracks and delamination in the non-continuous DLC layer  264  (DLC layer portions  264 B) may be suitably prevented. 
     Furthermore, the plural DLC layer portions  264 B are separated from each other with the grooves  266  therebetween, and the grooves  266  are formed at an angle that is toward the belt axial direction central portion when facing in the sliding direction of the fixing belt  38  from the upstream side toward the downstream side. Therefore, a lubricant flows in the direction toward the belt axial direction central portion during the sliding of the fixing belt  38 , and uneven distribution of the lubricant to the two edge portions, together with leaking of the lubricant, may furthermore be suitably prevented, and good sliding characteristics may be maintained over a long period of time. 
     Third Exemplary Embodiment 
     An image forming apparatus according to a third exemplary embodiment of the invention is the same as the image forming apparatus according to the second exemplary embodiment except that it has a characteristic surface shape of the substrate  262  of the fixed sliding member  244  and characteristic regions on which the plural DLC layer portions  264 B are formed. However, other than these characteristics, the configuration of the image forming apparatus according to the second exemplary embodiment may be used as it is. Explanation will therefore be given of the above characteristics, with explanation of other parts of the configuration omitted. 
       FIG. 7  is a schematic cross-section showing the surface of a fixed sliding member in the third exemplary embodiment. 
     A fixed sliding member  344  according to the third exemplary embodiment has a substrate  362  with an undulating surface (the inner peripheral surface) formed from protrusions  3622  and indentations  3624 . Plural DLC layer portions  364 B are formed to regions at least including the tops of the protrusions  3622 . 
     The same methods may be used for forming the non-continuous DLC layer portions  364 B to the regions including the tops of the protrusions  3622  on the surface of the substrate  362  as are used for forming the DLC layer portions  64 B in the first exemplary embodiment. 
     The surface of the substrate  362  is undulated, and by forming the non-continuous DLC layer  364  to regions thereof including at least the tops, cracking and delamination may be suitably prevented from occurring in the non-continuous DLC layer  364  (DLC layer portions  364 B), and good releasing characteristics may be obtained by a reduction in the contact surface area to the fixing belt  38 . 
     It should be noted that while embodiments of the fixing device  32  are shown in the second and third embodiments in which the fixed sliding member  244  or the fixed sliding member  344  have been formed to have the non-continuous DLC layer  264  or the non-continuous DLC layer  364  thereon, the fixed sliding member of the invention is not limited to application thereto, and, for example, the fixed sliding member may be used for a photoreceptor cleaning blade or the like in an image forming apparatus. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents. 
     EXAMPLES 
     Hereinafter, examples will be given of the image forming apparatuses according to the above exemplary embodiments of the invention. 
     Example 1 
     An image forming apparatus according to the second exemplary embodiment is prepared using the following components for the members used.
         Fixing belt  38 : a belt formed with a belt substrate  62  (stainless steel (SUS)) having thereon a PFA outer peripheral surface layer (PFA: tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer) (belt diameter: 35 mm)   Pressure roll  40 : a member in which a PFA layer is formed on the surface of an elastic layer (silicone sponge) (diameter: 35 mm)   Fixed sliding member  244 : a member in which non-continuous layer shaped plural DLC layer portions  264 B are formed on a sliding surface of a substrate  262  (silicone rubber) (grooves  266  are formed at an angle that is toward the belt axial direction central portion when facing in the sliding direction of the fixing belt  38  from the upstream side toward the downstream side)       

     Comparative Example 1 
     An image forming apparatus is prepared that is of the same configuration as the image forming apparatus of Example 1, except that a fluororesin layer (continuous layer) is formed in place of the non-continuous DLC layer  264  of the fixed sliding member  244  of Example 1. 
     Comparative Example 2 
     An image forming apparatus is prepared that is of the same configuration as the image forming apparatus of Example 1, except that a continuous DLC layer is formed in place of the non-continuous DLC layer  264  of the fixed sliding member  244  of Example 1. 
     Evaluation 
     The image forming apparatuses of Example 1 and Comparative Examples 1 and 2 are driven, the change in the fixing belt driving torque with time is measured, and the abrasion of the fixed sliding member is observed. 
     As shown in  FIG. 8 , in the Comparative Example 1, the initial driving torque is good, but a reduction in the sliding properties occurs due to abrasion of the fluororesin layer, and the driving torque increases. 
     In the Comparative Example 2, initially good properties are maintained, but a reduction in the sliding properties occurs due to delamination of the continuous DLC layer, and the driving torque increases. 
     In the Example 1, there is no reduction in the sliding properties due to abrasion of the sliding member, and no delamination occurs, the sliding properties are maintained over a prolonged period of time and an increase in the driving torque is prevented. 
     Example 2 
     An image forming apparatus is prepared that is of the same configuration as the image forming apparatus of Example 1, except that 0.5 g of a lubricating oil is applied to the sliding surface (the inner peripheral surface of the fixing belt  38 ) of the fixing belt  38  against the fixed sliding member  244 . 
     Example 3 
     An image forming apparatus is prepared that is of the same configuration as that of Example 2, except that the grooves  266  in the fixed sliding member  244  of Example 2 are formed in a lattice (that is, formed with grooves that are parallel to the belt axial direction and grooves that are parallel to the belt circumferential direction). 
     Evaluation 
     The image forming apparatuses of Examples 2 and 3 are driven, and any leakage of the lubricating oil is observed. 
     There is a small amount of leakage of the lubricating oil observed from the two edge portions of the fixing belt of Example 3. However, there is no leakage of the lubricating oil observed from the fixing belt of Example 2. 
     Example 4 
     An image forming apparatus according to the third exemplary embodiment is prepared using the following components for the members used.
         Fixing belt  38 : a belt formed with a belt substrate  62  (SUS) having thereon a PFA outer peripheral surface layer (belt diameter: 35 mm)   Pressure roll  40 : a member in which a PFA layer is formed on the surface of an elastic member (silicone sponge) (diameter: 35 mm)   Fixed sliding member  244 : a member in which a non-continuous layer shaped DLC layer  264  is formed on the sliding surface on a substrate  262  (silicone rubber) (the surface of the substrate  262  has undulations thereon, with the DLC layer portions  264 B formed on regions including at least the tops of the undulations)
 
Evaluation
       

     The change in the driving torque of the fixing belt with time is measured, and the abrasion of the fixed sliding member is observed in the same manner as in Example 1 and Comparative Examples 1 and 2. As shown in  FIG. 8 , in Example 4 there is no reduction in the sliding properties due to abrasion of the sliding member, and no delamination occurs, and the sliding properties are maintained over a prolonged period of time and an increase in the driving torque is prevented.