WO2022093302A1

WO2022093302A1 - Heat treatment device

Info

Publication number: WO2022093302A1
Application number: PCT/US2021/017566
Authority: WO
Inventors: Manabu Ono; Takeshi Kawamura
Original assignee: Hewlett Packard Development Co LP
Current assignee: Hewlett Packard Development Co LP
Priority date: 2020-10-30
Filing date: 2021-02-11
Publication date: 2022-05-05
Anticipated expiration: 2023-04-30
Also published as: JP2022073077A

Abstract

An example heat treatment device includes a toner-layer-forming device to supply toner, and an endless belt including a toner-layer-forming portion to receive a layer of toner from the toner-layer-forming device, and a transfer-and-fixing portion to transfer and fix the layer of toner to a medium. The endless belt generates heat in the transfer-and-fixing portion, in response to an electric power supply, during a rotation of the endless belt.

Description

HEAT TREATMENT DEVICE, IMAGE FORMING DEVICE, PROCESS CARTRIDGE, AND HANDY-TYPE HEAT TREATMENT DEVICE BACKGROUND [0001] Some gloss imparting devices and belt type fixing devices have been proposed in order to increase the glossiness of a color image obtained by an electrophotographic method. For example, one method of forming a high-gloss image involves superimposing a transparent toner image on a paper medium on which a color toner image is fixed in advance, heating and melting the toner image using a belt-type heating and fixing device, and then cooling and peeling off the paper medium. Further, in recent years, there has been an attempt, in addition to applying a transparent toner to a print material, to additionally superimpose a toner image of a decorative toner or an invisible toner for security, as a new way of adding value to a printed material. BRIEF DESCRIPTION OF DRAWINGS [0002] FIG. 1A is a schematic diagram illustrating a configuration of an example heat treatment device. FIG. 1B is another schematic diagram illustrating a configuration of the example heat treatment device and biases applied to portions of the heat treatment device. FIG. 2 is a schematic diagram illustrating another example heat treatment device. FIG. 3 is a schematic diagram illustrating another example heat treatment device. FIG. 4 is a schematic diagram illustrating a an example image forming device including the heat treatment device of FIG.3. FIG. 5 is a schematic diagram illustrating another example heat treatment device. FIG. 6A is a schematic diagram illustrating an operational state of an example heat treatment device . FIG. 6B is a schematic diagram illustrating a relationship between a bias voltage applied to respective portions of the example heat treatment device of FIG. 6A and a surface potential of an endless belt of the example heat treatment device. FIG. 7A is a schematic diagram illustrating an operational state of the example heat treatment device. FIG. 7B is a schematic diagram illustrating a relationship between a bias voltage applied to respective portions of the example heat treatment device of FIG.7A and a surface potential of the endless belt. FIG. 8A is a schematic diagram illustrating an operational state of the example heat treatment device. FIG. 8B is a schematic diagram illustrating a relationship between a bias voltage applied to respective portions of the example heat treatment device of FIG.8A and a surface potential of the endless belt. FIG. 9A is a schematic diagram illustrating an operational state of the example heat treatment device. FIG. 9B is a schematic diagram illustrating a relationship between a bias voltage applied to respective portions of the example heat treatment device and a surface potential of the endless belt. DETAILED DESCRIPTION [0003] Hereinafter, examples of a heat treatment device will be described. The dimensions, materials, shapes, relative arrangements, and the like of the components described below are appropriately changed depending on various conditions or the configuration of the device to which the present disclosure is applied and are not intended to limit the scope of the present disclosure. In the following description, with reference to the drawings, the same reference numbers are assigned to the same components or to similar components having the same function, and overlapping description is omitted. [0004] An example heat treatment device includes: an endless belt to generate heat in a rotation state by a voltage applied thereto, and a toner layer forming device to form a toner layer on the endless belt. The endless belt includes a toner layer forming portion to form the toner layer on the endless belt and a transferring and fixing portion to transfer and fix the toner layer to a medium in a heat generation state. The toner layer formed on the endless belt is transferred onto a sheet-like medium and is heated and fixed thereto, for example, when a sheet-like medium such as paper is conveyed. Accordingly, a toner image based on the shape of the toner layer is newly added onto the sheet-like medium. According to examples, the heat treatment device can be used in a fixing device or the like, that is mounted in an electrophotographic image forming apparatus (or electrophotographic image forming device). [0005] An example heat treatment device 1 illustrated in FIGS. 1A and 1B includes an endless belt 11 which can generate heat in a rotation state by a voltage applied thereto and a toner layer forming device (also referred to as a toner-layer-forming device) 20 which forms a toner layer on the endless belt 11. The endless belt 11 includes a toner layer forming portion D which forms a toner layer on the endless belt 11 and a transferring and fixing portion (also referred to as a transfer-and-fixing portion) F which transfers (or applies) and fixes the toner layer to a medium in a heat generation state. [0006] The toner layer forming device 20 includes a toner storage chamber 24 which stores a toner T, a toner carrier 21 which is rotatably disposed and carries and conveys the toner T inside the toner storage chamber 24, and a toner regulation member 25 that regulates (or limits) a thickness of a layer of the toner T carried on the toner carrier 21. [0007] A suspension roller 12 which suspends (or supports) the endless belt 11 is disposed to face the toner carrier 21 with a base portion of the endless belt 11 interposed therebetween. The toner layer forming portion D is formed between the toner carrier 21 and the suspension roller 12 so as to move the toner T carried on the toner carrier 21 onto the outer circumferential surface of the endless belt 11 when a moving bias (also referred to as a transfer bias) is applied thereto. [0008] The toner layer forming portion D may have a contact type configuration in which the toner carrier 21 and the endless belt 11 are in contact with each other, with the toner T carried on the toner carrier 21 interposed therebetween. In other examples, the toner layer forming portion D may have a non-contact type configuration in which the toner carrier 21 and the endless belt 11 are separated (or spaced apart) from each other, so as not to be in contact with each other. When the contact type is selected, since the toner is easily moved from the toner carrier 21 to the endless belt 11, the moving bias (or transfer bias) applied between the toner carrier 21 and the suspension roller 12 is generated by a DC component exclusively, and this configuration can contribute to the miniaturization of the device. On the other hand, when the non-contact type is selected, since the toner T is to be transferred from the toner carrier 21 to the endless belt 11 without any contact therebetween, an AC component is superimposed on a DC component in the moving bias. Consequently, durability and operation speed may be increased, although the device may be increased in size. [0009] The example toner layer forming device 20 illustrated in FIG.1A adopts the contact type and the moving bias having a DC component (without an AC component) is applied between the toner carrier 21 and the suspension roller 12. The toner carrier 21 is formed as a conductive elastic roller and rotates in the same direction as the endless belt 11. The rotating speed of the toner carrier 21 is set so that the movement amount of the toner T onto the endless belt 11 reaches a targeted amount and is adjusted by the amount of the toner T carried on the toner carrier 21 and the speed ratio with respect to the moving speed of the endless belt 11. The speed ratio of the rotating speed of the toner carrier 21 with respect to the moving speed of the endless belt 11 may be within the range of 1.0 to 2.5. A speed ratio that is less than 1.0, may lead to an unsuitable charged state or an unsuitable movement amount of the toner T onto the endless belt 11. On the other hand, a speed ratio that exceeds 2.5, may cause scattering or deterioration of the toner T carried on the toner carrier 21. [0010] The amount of the toner T carried on the toner carrier 21 is adjusted by a toner supply roller 22 and the toner regulation member 25 which are disposed to contact the circumferential surface of the toner carrier 21. [0011] The toner supply roller 22 is a supply member for supplying the toner T supplied by the rotation of a conveyance member 23 provided in the toner storage chamber 24 and the toner T scraped off from the toner carrier 21 by the toner regulation member 25 which will be described further below, to the toner carrier 21. [0012] The toner supply roller 22 may be formed of an elastic member such as polyurethane foam, so as to be elastically deformable, and contacts the toner carrier 21 in the elastically deformed state. For example, the toner supply roller 22 may rotate counterclockwise and move in the direction opposite to the toner supply roller 22 in the contact region with the toner supply roller 22 rotating counterclockwise in the same way. The toner T supplied from the conveyance member 23 adheres to the surface of the toner supply roller 22. When the surface of the toner supply roller 22 comes into contact with the surface of the toner carrier 21, the toner T is supplied from the toner supply roller 22 to the toner carrier 21 and the toner is carried on the toner carrier 21. Further, the toner supply roller 22 peels off the toner T not used for the forming portion D, from the toner carrier 21 at the same time as the toner T is supplied. The toner supply roller 22 also prevents the toner T from staying on the toner carrier 21 and causing an excessive increase in charge amount. [0013] The toner regulation member 25 illustrated in FIG.1A is a member that adjusts the toner T carried on the toner carrier 21. The toner regulation member 25 extends in the axial direction of the toner carrier 21, and is disposed to contact the circumferential surface of the toner carrier 21. [0014] The toner regulation member 25 may be formed of a plate-shaped member, for example, made of phosphor bronze, stainless steel, or the like. The toner T carried on the toner carrier 21 can be adjusted to a targeted amount by the press-contact state of the toner regulation member 25 with respect to the toner carrier 21 and the shape of the free end portion of the toner regulation member 25. [0015] The endless belt 11 is stretched (or tensioned) around the suspension roller 12, a peeling member 13, and a pressing member 16. The pressing member 16 is pressed against a pressing roller (or pressure roller) 15 by a pressing mechanism. The pressing member 16 and the pressing roller 15 form a nip portion to position the endless belt 11 therebetween, and the endless belt 11 rotates in a following manner in accordance with the rotation of the pressing roller 15. A sheet-like medium (e.g., a sheet of paper) P is introduced and conveyed between the endless belt 11 and the pressing roller 15, and faces the outer circumferential surface of the endless belt 11 and the toner layer formed on the endless belt 11. [0016] The pressing member 16 includes a first electrode portion (or first electrode) 17 and a second electrode portion (or second electrode) 18 which extend in the axial direction of the endless belt 11 and form a nip portion NP therebetween. The first electrode portion 17 is positioned on the upstream side of the second electrode portion 18, in the rotation direction of the endless belt 11. The first electrode portion 17 and the second electrode portion 18 contact a base portion constituting the inner circumferential surface of the endless belt 11. Each of the first electrode portion 17 and the second electrode portion 18 has a plate shape and extends in the axial direction of the endless belt 11. The first electrode portion 17 is disposed to be separated (or spaced apart) from the second electrode portion 18 in a direction intersecting the axial direction. A short-circuit preventing insulation portion is provided between the first electrode portion 17 and the second electrode portion 18. A power source device is connected between the first electrode portion 17 and the second electrode portion 18 and a fixing bias supplied from the power source device generates heat on the inner circumferential surface along a segment of the endless belt 11 that extends from the downstream end portion of the first electrode portion 17 to the upstream end portion of the second electrode portion 18, so that a heat generation region H1 is formed. [0017] The toner layer on the endless belt 11, facing the sheet-like medium P is heated when reaching the heat generation region H1 so that the toner layer starts to be softened. Then, the toner layer passes through the nip portion NP while contacting the sheet-like medium P which is conveyed by the endless belt 11 and the pressing roller 15 to pass therebetween. The nip portion NP forms a transferring and fixing portion and the toner layer on the endless belt 11 is simultaneously fixed to the surface of the sheet-like medium while being transferred thereto. [0018] The endless belt 11 is formed of a nanocomposite material in which carbon nanofiller is dispersed. The endless belt 11 serves as a heating body that generates heat by energization in the heat generating region. The nanocomposite material used for the base portion (base material portion) of the endless belt 11 is a composite material composited on a nanoscale, in which carbon filler is dispersed in a matrix resin. [0019] In most composite materials, repeated deformation due to an external force causes shear stress or displacement stress in the internal structure and tends to cause a decrease in strength. This tendency is accelerated by repeated energization and heat shock. [0020] A volume resistivity A of the endless belt 11 in the rotation direction (hereinafter, referred to as the "volume resistivity A in the rotation direction") may be set to be less than a volume resistivity B of the endless belt 11 in the axial direction (hereinafter, referred to as the "volume resistivity B in the axial direction"). In this case, the influence of the internal stress generated when the endless belt 11 is rotated can be reduced, so as to better maintain the conductive path. A ratio of the volume resistivity A in the rotation direction with respect to the volume resistivity B in the axial direction (hereinafter, referred to as the "volume resistivity ratio A/B") may be within a range of 0.50 to 0.95. In this case, it is possible to significantly reduce an increase in the applied voltage during continuous use of the endless belt 11. Further, the volume resistivity ratio A/B may be within a range of 0.60 to 0.85, to stabilize the rotational movement of the endless belt 11 in a heat generation state and reduce occurrences of gloss unevenness in the fixed image. [0021] Examples of the carbon filler used for the base portion of the endless belt 11 include, for example, carbon fibers, carbon nanotubes (hereinafter, referred to as "CNT"), whiskers made of carbon-based materials, and the like. Any one of such examples or a combination thereof may be used to form the carbon filled. Among these, CNT is used as an example. Further, the diameter may be within a range of 2 nm to 20 nm and the ratio of the length with respect to the diameter (hereinafter, referred to as the "aspect ratio") may be within a range of 100 to 150,000. A diameter that exceeds 20 nm or an aspect ratio that is less than 100 may not be suitable to form a conductive path. Additionally, an aspect ratio that exceeds 15,000, may cause insufficient dispersion in the matrix material. [0022] The content of the carbon filler may be within a range of 3% by mass to 25% by mass, or within a range of 5% by mass to 20% by mass. If the content of the carbon filler is insufficient, sufficient heat generation characteristics may not be obtained. Further, if the content of the carbon filler is excessive, the base portion of the endless belt 11 may become too rigid, the mechanical strength may be impaired, and the volume resistivity A/B may not be easily adjusted. [0023] Examples of the matrix material used for the base portion of the endless belt 11 include, for example, a polyimide resin or a polyamide-imide resin. Any one of such examples or a combination thereof may be used to form the matrix material. Such matrix material exhibits suitable heat generation characteristics in addition to suitable mechanical properties, thermal stability, chemical stability, and the like. [0024] The base portion of the endless belt 11 is manufactured so that the volume resistivity A of the endless belt 11 in the rotation direction is less than the volume resistivity B of the endless belt 11 in the axial direction. The base portion of the endless belt 11 can be manufactured by using any suitable manufacturing method. For example, the base portion can be treated and molded from a coating liquid. The coating liquid is obtained by dispersing carbon filler in a matrix material, or in a raw material of the matrix material that is dissolved in a solvent or that is heated to melt. The coating is applied to a mold, then dried or heated, and in some cases, the coating may be subjected to a flame treatment. In some examples, a coating liquid having dispersed therein a carbon filler having a specific shape, may be applied to the surface of the mold from a dispenser having a small-diameter discharge port or the like, so as to adjust the orientation state of the carbon filler in the endless belt and to impart suitable characteristics to the endless belt. [0025] The endless belt 11 may have a structure including a heat generation layer, an intermediate layer and a surface layer, in which a base of a nanocomposite material obtained by dispersing carbon filler is set as the heat generation layer, and in which the intermediate layer is laminated on the heat generation layer, either directly or via an adhesive layer, and the surface layer is laminated on the intermediate layer, either directly or via an adhesive layer. In other examples, the intermediate layer can be omitted, and in that case, the surface layer is laminated on the heat generation layer directly or via an adhesive layer. [0026] A material having suitable heat resistance and elasticity such as silicone rubber may be used for the intermediate layer of the endless belt 11 so as to impart elasticity to the endless belt 11. For example, the intermediate layer can be easily manufactured by curing the silicone rubber applied on the heat generating layer. Accordingly, the external force on the base portion of the endless belt 11 can be absorbed by the elasticity of the intermediate layer. As a result, the influence of the internal stress generated when the endless belt 11 is rotated can be reduced, so as to better maintain the conductive path. The thickness of the intermediate layer may be within a range of 0.3 mm to 3 mm. A thickness of the intermediate layer that is less than 0.3 mm, may exhibit insufficient elasticity. A thickness of the intermediate layer that exceeds 3 mm, may exhibit insufficient flexibility of the base portion of the endless belt 11. [0027] A surface layer may be provided on the outer circumferential surface of the endless belt 11. As the surface layer of the endless belt 11, for example, a material having suitable heat resistance and releasability such as a fluororesin may be used. Examples thereof include polytetrafluoroethylene (PTFE), perfluoroalkoxy alkane resin (PFA), and fluorinated ethylene/propylene hexafluorinated copolymer (FEP). Additionally, additives may be dispersed in such fluororesins and the like, to impart properties such as flame retardancy and antistatic properties. The surface layer may be formed by a method of sintering the applied fluororesin, a method of coating a fluororesin tube, or the like, according to examples. The thickness of the surface layer may be 1/2 or less of the thickness of the base portion (e.g., the heat generation layer) of the endless belt 11 and the volume resistivity of the surface layer may be 10 times or more the volume resistivity A of the base portion in the rotation direction. A thickness of the surface layer that exceeds 1/2 of the base portion (e.g., the heat generation layer) of the endless belt 11, may exhibit insufficient flexibility of the base portion of the endless belt 11. Additionally, a volume resistivity of the surface layer that is less than 10 times the volume resistivity A of the rotational resistivity of the base portion, may cause the formation of a new energization path inside the endless belt 11 so as to deteriorate the energization efficiency to the heat generating layer. [0028] According to examples of the heat treatment device, the moving bias (or transfer bias) applied to the suspension roller 12 also serves as the fixing bias. Accordingly, the power source device or control circuit can be simplified and a new heat generation region H2 can be provided between the suspension roller 12 and the first electrode portion 17. [0029] As illustrated in FIG.1B, the first electrode portion 17 is grounded, and additionally, the fixing bias applied to the second electrode portion 18 and the fixing bias applied to the suspension roller 12 and also serving as the moving bias, are set to the same potential. Accordingly, in addition to the heat generation region H1, a heat generation region H2 is formed by generating heat on the inner circumferential surface of the endless belt 11. The heat generation region H2 is formed along a segment of the endless belt 11, that extends from a separation portion of the suspension roller 12 and the endless belt 11, where the endless belt 11 extends away from the suspension roller 12, to the upstream end portion of the first electrode portion 17. Accordingly, the toner layer moving to the heat generation region H1 in accordance with the rotation of the endless belt 11 may be heated in advance, so as to reduce the fixing load in the transferring and fixing portion F. [0030] The heat generation temperature in the heat generation region H1 is set based on the length of the segment of the endless belt 11 extending from the downstream end portion of the first electrode portion 17 to the upstream end portion of the second electrode portion 18, in the rotation direction of the endless belt 11, and based on the increase and decrease of the input voltage of the fixing bias. Additionally, the heat generation temperature in the heat generation region H2 is set based on the length of the segment of the endless belt 11 extending from the separation portion of the suspension roller 12 and the endless belt 11 to the upstream end portion of the first electrode portion 17, in the rotation direction of the endless belt 11, and based on the increase and decrease of the input voltage of the fixing bias. [0031] In the example heat treatment device 1 illustrated in FIG. 1A, the temperature of the outer circumferential surface of the endless belt 11 in the heat generation region H1 is set to be equal to or greater than a deformation temperature of the toner layer, corresponding to a temperature at which the material forming the toner layer formed on the endless belt 11 can be deformed. The temperature of the outer circumferential surface of the endless belt in the heat generation region H2 is set to a temperature which is lower than the glass transition temperature (Tg) exhibited by the toner T, by 15qC or more, to achieve a suitable storability of the toner T stored in the toner storage chamber 24. [0032] Since the fixing bias applied to the second electrode portion 18 and the fixing bias applied to the suspension roller 12 and also serving as the moving bias, are set to the same potential, the inner circumferential surface of the segment of the endless belt 11 that extends from the downstream end portion of the second electrode portion 18 to a contact portion of the suspension roller 12 and the endless belt 11, where the endless belt 11 comes into contact with the suspension roller 12, does not generate heat. Accordingly, the endless belt 11 having passed through the heat generation region H1 returns to the toner layer forming portion D while being deprived of heating, so as to protect the toner layer forming portion D from an excessive rise in temperature. In addition, the base layer portion of the endless belt 11 is made of a nanocomposite material in which carbon filler is dispersed, so as to exhibit suitable heat generation characteristics and thermal conductivity. As a result, the endless belt 11 is efficiently cooled in the region L corresponding to the segment extending from the downstream end portion of the second electrode portion 18 to the contact portion of the suspension roller 12 and the endless belt 11, in the rotation direction of the endless belt 11. [0033] The suspension roller 12 is a conductive member that may have a substantially cylindrical shape and may be formed of any suitable material. The curvature of the suspension roller 12 is set to be less than the curvature of the toner carrier 21, in order to stabilize the movement state of the toner T in the toner layer forming portion D. According to examples, the curvature of the suspension roller 12 may be less than 0.86 relative to the curvature of the toner carrier 21, so as to form a uniform toner layer on the endless belt 11. [0034] The pressing roller 15 is rotationally driven by a motor of which a rotation is controlled by a rotation control section (or rotation control device). While the endless belt 11 rotates in a following manner as the pressing roller 15 is rotationally driven, the energization of the first electrode portion 17 and the second electrode portion 18 is carried out to control the heat generation state of the endless belt 11 in the heat generation region H1 between the first electrode portion 17 and the second electrode portion 18. [0035] The pressing roller 15 may include an elastic layer formed around a core metal. The elastic layer is made of heat-resistant silicone rubber or the like, that exhibits a suitable elasticity. The core metal is made of a metal material such as an aluminum material or a steel use stainless (SUS) material. The pressing roller 15 may include a mold release layer exhibiting releasability on its outermost surface. [0036] The peeling member 13 guides the endless belt 11 to move in a direction orthogonal to its axial direction at a predetermined position where peels off the sheet-like medium P in close contact with the outer circumferential surface of the endless belt 11 is peeled off due to the rigidity of the sheet-like medium P. The peeling member 13 may include a metal material that is formed in a roller shape or a cylindrical shape, for examples. For example, a cylindrical member having suitable thermal conductivity may be used as the peeling member 13, so that the endless belt 11 can be more easily cooled slowly, and so as to increase the productivity, and increase the range of adjusting the glossiness that can be imparted to the fixed image on the sheet-like medium P. [0037] With reference to FIG. 1A, the peeling member 13 may be a roller-shaped member, so as to tiltably mount the peeling member 13, for example by fixing a first end of the shaft of the peeling member 13 and supporting a second end so as to be displaced with respect to the axial direction of the endless belt 11 by a displacement mechanism. Accordingly, the endless belt 11 may be movable in a reciprocating manner in the axial direction. For the movement operation of the endless belt 11 by the peeling member 13 and the displacement mechanism, the position of the side end portion of the endless belt 11 is detected by a position detection sensor or the like and the movement operation is controlled based on the detection information. Any suitable method may be selected for the driving means of the displacement mechanism, the control method of the movement operation, and the like. [0038] The base layer portion of the endless belt 11 is supported around the peeling member 13, and adheres to the outer circumferential surface of the peeling member 13. The base layer portion of the endless belt 11 may be made of a nanocomposite material in which carbon filler is dispersed, so as to achieve suitable heat generation characteristics and thermal conductivity. As a result, the endless belt 11 is efficiently cooled by the peeling member 13. The external dimensions of the peeling member 13 are set based on the adhesive force between the endless belt 11 and the fixed image on the sheet-like medium P and a winding angle formed by linear portions of the endless belt that extend from the peeling member 13. The toner layer on the endless belt 11 is simultaneously transferred and fixed to the sheet-like medium P to form a fixed image T, by the heat generated in the endless belt 11 and the pressure generated in the pressing roller 15. The toner layer is in close contact with the outer circumferential surface of the endless belt 11 while the sheet-like medium P passes through the heat generation region H1. Accordingly, the smoothness exhibited by the outer circumferential surface of the endless belt 11 is transferred to the fixed image T on the sheet-like medium P while being in close contact with the endless belt 11, so as to impart gloss to the surface of the fixed image T. [0039] According to examples of the heat treatment device, the surface potential of the outer surface layer of the endless belt 11 is adjusted before the moving bias (of transfer bias) is applied at the toner layer forming portion D, so as to more easily control the shape or amount of the toner layer to be formed on the endless belt 11. [0040] With reference to FIG. 1A, a charging device 19 may be disposed to face the outer circumferential surface corresponding to a region L of the endless belt 11. The charging device 19 may be a brush-type contact charging device extending in the axial direction of the endless belt 11, that provides two rows of conductive brushes including conductive fibers, in which the two rows are spaced apart in the movement direction of the endless belt 11. Among the conductive brushes, the conductive brushes in the front row (or first row located at an upstream position) in the movement direction of the endless belt 11 are grounded. The conductive brushes in the back row (or second row located at a downstream position) are divided in the axial direction of the endless belt 11 and a selected divided portion can be charged by applying a charging bias from an external power source. [0041] When the charging bias is applied to the charging device 19, a charged portion C is formed between the charging device 19 and the endless belt 11 and a surface potential according to the charging bias can be obtained. Accordingly, the layer thickness of the toner layer formed on the endless belt 11 can be made uniform or continuously changed. [0042] The charging device 19 may eliminate static electricity from the outer surface layer of the endless belt 11. The outer surface layer of the endless belt 11 may be charged after eliminating static electricity therefrom in advance, to increase the uniformity of the toner layer formed on the endless belt 11 and to prevent the toner adhesion in a portion to be free of the toner layer. [0043] In addition to the brush type, a blade type or roller type contact charging device or a corotron type non-contact charging device can be used as the charging device 19. For example, the contact charging device may be selected, to set the charging bias to the DC component exclusively, which contributes to miniaturization or size reduction of the heat treatment device. Accordingly, the heat treatment device can be more easily made into a cartridge or handy type (e.g., handheld or portable type) by using the charging bias as a DC component together with the moving bias or the fixing bias. [0044] Examples of the heat treatment device 1 can take various forms by modifying the arrangement or the like of the components, depending on the relative position or the like of the toner layer forming device 20 with respect to the treatment direction of the sheet-like medium which is an object to be treated, or the movement path of the object to be treated. [0045] In an example heat treatment device 1A illustrated in FIG. 2, the relative placement position of a toner layer forming device 40 with respect to the movement path of the object to be treated is the lower side while the treatment direction of the sheet-like medium remains horizontal, although the front and back sides of the sheet-like medium are reversed. The heat treatment device 1A includes an endless belt 31, a suspension roller 32, a peeling member 33, a pressing roller (or pressure roller) 35, a pressing member 36, a first electrode portion 37, a second electrode portion 38, a charging device 39, a toner carrier 41, a toner supply roller 42, a conveyance member 43, a toner storage chamber 44, and a toner regulation member 45. [0046] The relative position of the toner layer forming device 40 with respect to the movement path of the object to be treated is disposed at the lower side, so as to reduce or minimize the risk of contamination of the surface of the object to be treated by the toner T leaking from the toner layer forming device 40. Additionally, the toner layer forming device 40 can be disposed below the endless belt 31 which is a heat source, so as reduce or minimize the risk of thermal deterioration of the toner T stored in the toner storage chamber 44. [0047] The toner layer forming device 40 of the heat treatment device 1A has a configuration in which the toner T is pumped from the toner storage chamber 44 disposed at the bottom toward the toner carrier 41. A new toner supply chamber 46 is disposed adjacently above the toner storage chamber 44. The toner supply chamber 46 is provided with a toner supply roller 42 which is disposed to face and contact the toner carrier 41 and a stirring member 49 that prevents toner packing. The toner supply chamber 46 supplies the toner T to the toner supply roller 42. The toner supply chamber 46 may form a space for resupplying the toner stripped from the toner carrier 41 by the toner supply roller 42 to the toner supply roller 42 without returning the toner to the toner storage chamber 44, so as to prevent excessive deterioration of the toner T. [0048] A partition wall 47 is provided between the toner storage chamber 44 and the toner supply chamber 46, an opening portion 48 is provided in the partition wall 47, and the toner storage chamber 44 and the toner supply chamber 46 are connected to each other through the opening portion 48. The toner storage chamber 44, the toner supply chamber 46, and the partition wall 47 are integrally formed with each other. [0049] The toner storage chamber 44 is provided with a conveyance member 43 that conveys the toner T to the toner supply chamber 46. The conveyance member 43 may rotate so that a predetermined amount of the toner T stored in the toner storage chamber 44 is conveyed into the toner supply chamber 46 through the opening portion 48 of the partition wall 47. [0050] In an example heat treatment device 1B illustrated in FIG. 3, the treatment direction of the sheet-like medium is a vertical direction and the relative placement position of a toner layer forming device 60 with respect to the movement path of the object to be treated is a horizontal direction. The heat treatment device 1B includes an endless belt 51, a suspension roller 52, a peeling member 53, a pressing roller (or pressure roller) 55, a pressing member 56, a first electrode portion 57, a second electrode portion 58, a charging device 59, a toner carrier 61, a toner supply roller 62, a conveyance member 63, and a toner regulation member 65. [0051] The example heat treatment device 1B may minimize the risk of contamination by the toner T and the risk of thermal deterioration of the toner T similarly to the example heat treatment device 1A. Additionally, the treatment direction of the sheet-like medium may be in the vertical direction so as to more easily mount the heat treatment device on a full-color printer using an electrophotographic method as a fixing device or a post-processing device immediately after the fixing device. [0052] FIG. 4 illustrates an example image forming apparatus (or image forming device) in which the heat treatment device 1B illustrated in FIG. 3 is mounted as a fixing device of a full-color printer using an electrophotographic method. In this case, a toner layer which is a color toner image formed in advance by a color image forming portion is provided on the surface of the sheet-like medium P which is an object to be treated. The example heat treatment device 1B may operate similarly to the other fixing devices and can perform an additional heat treatment on the sheet-like medium P using the toner T stored in a toner storage chamber 124. [0053] An image forming apparatus (or image forming device) 100 illustrated in FIG. 4 forms, for example, a color image using the toners of respective colors of magenta, yellow, cyan, and black. The image forming apparatus 100 includes, for example, a conveyance route 171 which conveys the sheet-like medium P such as a printing sheet, a developing device 120 which develops an electrostatic latent image into a toner image, and a transfer device 130 which transfers the toner image to a recording material such as the printing sheet to print the toner image thereon. Further, the image forming apparatus 100 includes an image carrier 140 on which the electrostatic latent image is formed, the heat treatment device 1B which is a fixing device that additionally operates for heat treatment, and a discharge roller 162 which discharges a recording material. [0054] According to examples, the recording material (the sheet-like medium P) which is accommodated in a cassette K in a stacked state is picked up by a paper feeding roller 135 and is conveyed along the conveyance route 171. The recording material reaches a secondary transfer region 172 through the conveyance route 171 at a timing at which the toner image to be transferred reaches the secondary transfer region 172. The developing device 120 includes a developing roller 121 which develops a toner on the image carrier 140. The transfer device 130 may convey the toner image formed by the developing device 120 to the secondary transfer region 172 where the toner image is secondarily transferred to the recording material. The transfer device 130 includes a transfer belt 131, a suspension roller 132, a primary transfer roller 133, and a secondary transfer roller 134. The developing device 120, a charging roller 141, an exposure unit (or exposure device) 142, and a cleaning unit (or cleaning device) 170 are provided around the image carrier 140. [0055] The charging roller 141 charges the surface of the image carrier 140. The exposure unit 142 exposes the surface of the image carrier 140 charged by the charging roller 141 according to an image to be formed on the recording material. Four developing devices 120 develop the electrostatic latent image formed on the respective image carriers 140 with the toner supplied from the respective toner tanks N to form the toner image. The toner tanks N are respectively filled with magenta, yellow, cyan, and black toners. The cleaning unit 170 collects the toner remaining on the image carrier 140 after the toner image formed on the image carrier 140 is primarily transferred to the transfer belt 131. [0056] In the image forming apparatus (or image forming device) 100, the example heat treatment device 1B operates as a fixing device for an additional heat treatment. For example, the heat treatment device 1B fixes the toner image secondarily transferred from the transfer belt 131 to the recording material (the sheet-like medium P) while pressing the toner image against the recording material in a heated state (fixing operation) and forms the toner layer on an endless belt 111 using the toner T stored in the toner storage chamber 124. Accordingly, the heat treatment device 1B may simultaneously perform various additional heating treatments (heat treatment operations). Subsequently, the pair of discharge rollers 162 discharges the recording material having a fixed image and having been subjected to the additional heat treatment, to the outside of the image forming apparatus 100. [0057] According to examples, the image forming apparatus (or image forming device) 100 may include a recording material identification device 180 for identifying the state of the recording material (the sheet-like medium P). The recording material identification device 180 may be disposed along the conveyance route 171 of the recording material. The recording material identification device 180 acquires identification information such as the basis weight or surface smoothness of the recording material passing through the conveyance route 171 and outputs the identification information to a control unit (or controller) of the heat treatment device 1B. The control unit of the heat treatment device 1B may control the fixing operation and the additional heat treatment operation for the recording material of the heat treatment device 1B based on the acquired identification information, so as to impart a targeted glossiness according to the type of the sheet-like medium P. Namely, even in the same lot printing in which different types of recording materials are mixed, the degree of gloss can be adjusted according to the type of recording material in such a manner that the identification information of the recording material obtained by the recording material identification device 180 is fed back to the heat treatment device 1B. [0058] According to examples, the example heat treatment device 1B or a portion thereof excluding the pressing roller (or pressure roller) 115 can be used as a decorative process cartridge (e.g., process cartridge 125) that is attachable to and detachable from the main body of the example image forming apparatus (or image forming device) 100. [0059] In the present disclosure, "decoration" or "decorative" refers to the post-processing content applied to a printed image. "Decoration" may refer to gloss adjustment and waterproofing treatment using transparent toner, the adding-on of images such as gold and silver patterns, characters, and symbols, the adding-on of invisible images visualized by irradiation with black light, or post-processing such as adding fragrance to images. [0060] As the contents of such decorations may be numerous and varied as described above, the toner T stored in the toner storage chamber 124 is to be replaced at each post-processing. According to examples, the heat treatment device 1B or the portion of the heat treatment device 1B excluding the pressing roller 115 may be attachable to and detachable from the main body of the image forming apparatus (or image forming device) 100 to form the process cartridge 125. Accordingly, the process cartridge 125 may be detachably mounted to the image forming apparatus 100, as a replaceable cartridge that may be adapted for each type of toner corresponding to the targeted post-processing content, so as to add various decorations to an image with a single image forming apparatus. The process cartridge 125 may include, for example, a drive transmission unit (or drive transmission device) and a control signal transmission unit (or control signal transmission device) with respect to the image forming apparatus 100 which is an attachment and detachment target, and may additionally include an identification information storage unit (or storage device) storing setting information of each application bias used in the heat treatment device in addition to the heat treatment device 1B or the portion of the heat treatment device 1B excluding the pressing roller. The process cartridge 125 can be integrated and stored in a container (or a housing) 127 that accommodates the toner layer forming device 60 and the endless belt 51, and that is detachably mountable to the image forming apparatus 100, to provide a replaceable process cartridge. According to examples, the container 127 may be attachable and detachable via a guide member such as a rail provided in the image forming apparatus 100. [0061] FIG.5 illustrates another example in which the heat treatment device is a handy printer 1C (e.g., handy heat treatment device) that is sized to be portable or handheld. In this case, the object to be treated may be a three-dimensional object Y having a flat surface or a curved surface. The example handy printer 1C may be moved in a direction indicated by an arrow X while maintaining a state in which an endless belt 71 is positioned to extend between a pressing member 76 and the surface of the object to be treated, the toner layer formed by the toner T can be transferred and fixed to the surface of the three-dimensional object Y. [0062] The handy printer 1C includes an endless belt 71, a suspension roller 72, a peeling member 73, the pressing member 76, a first electrode portion 77, a second electrode portion 78, a charging device 79. The handy printer 1C does not include any pressing roller. The handy printer 1C fixes, for example, the toner T to the printing target by the heating of the endless belt 71 which is a self-heating belt and the pressing force of the endless belt 71 to the printing target. The handy printer 1C additionally includes a toner layer forming device 80 that includes a toner carrier 81, a conveying roller 82, a conveyance member 83, a stirring member 84, and a toner regulation member 85. [0063] The handy printer 1C includes the endless belt 71 which can generate heat in a rotation state by a voltage applied thereto and the toner layer forming device 80 which forms the toner layer on the endless belt 71. The endless belt 71 includes the toner layer forming portion D which forms the toner layer on the endless belt 71 and the transferring and fixing portion F which transfers and fixes the toner layer to the surface of the three-dimensional object Y in a heat generation state. [0064] The toner layer forming device 80 includes a toner storage chamber 86 which stores the toner T, the toner carrier 81 which is rotatable to as to carry and convey the toner T in the toner storage chamber 86, and the toner regulation member 85 which regulates the layer thickness of the toner T carried on the toner carrier 81. The suspension roller 72 which suspends (or supports) the endless belt 71 is disposed to face the toner carrier 81 with the base portion of the endless belt 71 interposed therebetween. The toner layer forming portion D is provided to transfer the toner T carried on the toner carrier 81 onto the outer circumferential surface of the endless belt 71 by applying a moving bias (or transfer bias) between the toner carrier 81 and the suspension roller 72. [0065] The endless belt 71 is stretched (or tensioned) around the suspension roller 72, the peeling member 73, and the pressing member 76. The pressing member 76 is pressed against the surface of the three-dimensional object Y by a pressing mechanism. The pressing member 76 and the surface of the three-dimensional object Y form a nip portion NP2 that nips the endless belt 71. The endless belt 71 rotates in accordance with the moving speed of the handy printer 1C. The surface of the three-dimensional object Y faces the outer circumferential surface of the endless belt 71 where the toner layer is formed. The toner layer on the endless belt 71 facing the surface of the three-dimensional object Y is heated when reaching the heat generation region H1 so that the toner layer starts to be softened. Then, the toner layer passes through the nip portion NP2 while contacting the surface of the three-dimensional object Y. The nip portion NP2 forms the transferring and fixing portion F and the toner layer on the endless belt 71 is simultaneously fixed to the surface of the three-dimensional object Y while being transferred thereto. [0066] Test examples of the image forming apparatus (or image forming device) will be described, although the present disclosure is not limited to the test examples described herein. [0067] Test Example 1 In a Test Example 1, a modified test machine was prepared so that the cartridge type heat treatment device 1B illustrated in FIG. 3 was attachable to and detachable from a fixing device part of M577dn (manufactured by HP Development Company, L.P.) corresponding to an electrophotographic color MFP and a print speed was adjusted to 16 ppm. The cartridge includes an identification information storage unit which stores setting information for each application bias used in the heat treatment device 1B in response to the stored toner type. The modified test machine can change and set the bias application condition or the like based on the setting information stored in the identification information storage unit whenever the cartridge is replaced. [0068] A negatively charged transparent toner (particle diameter; 6.5 Pm, Tg; 60qC) was stored in a toner storage chamber 64 of the heat treatment device 1B. As an example, it was set and designed so that the speed ratio of the rotating speed of the toner carrier 61 with respect to the moving speed of the endless belt 51 was 1.5 and the curvature of the suspension roller 52 was 0.67 with respect to the curvature of the toner carrier 61. Accordingly, the transparent toner in a well-charged state can be moved stably along the endless belt 51 without excess or deficiency. [0069] The endless belt 51 was obtained by coating a tube (thickness: 20 Pm) made of PFA with a polyimide composition (thickness: 67 Pm) containing 10% by mass of CNT. The volume resistivity of the endless belt 51 in the heat generation state is 0.16 :^cm in the rotation direction and 0.22 :^cm in the axial direction. A ratio between the volume resistivity in the rotation direction and the volume resistivity in the axial direction was 0.73. [0070] The charging device 59 was a brush-type contact charging device and was obtained by arranging two rows of conductive brushes using a conductive fiber in the movement direction of the endless belt 51, to be spaced apart from each other. In the conductive brushes, the front row (first row) of the conductive brush in the movement direction of the endless belt 51 is grounded. The back row (second row downstream the first row) of the conductive brush is divided so that a charging bias can be applied to a selected portion of the endless belt 51 in the axial direction. With reference to FIGS.6A and 6B, the charged portion in the axial direction was divided into three charged portions 591 to 593, a DC component of -600 v was applied to the charged portions (charged end portions) 591 to 593, and a charging bias was not applied to the charged portion (charged central portion) 592. As a result, the surface potential of the outer circumferential surface of the endless belt 51 at the portions corresponding to the charged portions 591 and 593 was -250 v and the surface potential at the portion corresponding to the charged portion 592 was r0 v. [0071] As a moving bias (or transfer bias), a DC component of -180 v was applied to the toner carrier 61 and a DC component of +20 v was applied to the suspension roller 52. As a result of applying the DC component of +20 v to the suspension roller 52, the surface potential of the outer circumferential surface of the endless belt 51 at the portions corresponding to the charged portions 591 and 593 was -230 v and the surface potential at the portion corresponding to the charged portion 592 changed to +15 v. [0072] A portion (central portion) of the endless belt 51, corresponding to the charged portion 592 causes a potential difference of +195 v with respect to the moving bias of -180 v applied to the toner carrier 61, such that the toner T which is a negatively charged transparent toner is transferred so as to form a toner layer. In this case, since the surface potential of the portion corresponding to the charged portion 592 to which the toner T is transferred is the potential generated by the influence of the elimination of static electricity by the charging device 59 and the moving bias applied to the suspension roller 52, there is relatively little variation in surface potential. Therefore, the toner layer having a uniform layer thickness is formed on the endless belt 51. On the other hand, the potential difference of the charged portions 591 and 593 with respect to the toner carrier 61 is -50 v, such that the negatively charged toner T does not transfer to the endless belt 51 so as to be prevented from adhering thereto. [0073] As a fixing bias, the first electrode portion 57 is grounded and a DC component of +20 v was applied to the second electrode portion 58. Consequently, the surface temperature of the endless belt 51 of the portion (see FIGS. 1A and 1B) corresponding to the heat generation region H1 partitioned by the first electrode portion 57 and the second electrode portion 58 reached 180qC. [0074] The toner layer formed on the portion corresponding to the charged portion 592 of the endless belt 51 was transferred and fixed to the recording material when passing through the contact region between the pressing member 56 and the pressing roller 55 while being in close contact with the recording material to which the color toner image was transferred in advance. As a result, a color print having a uniform transparent layer on the surface of the color image was obtained. In addition, no stains or the like due to the transparent toner were found at the portions (edge portions) of the endless belt 51 corresponding to the charged portions 591 and 593. [0075] Further, the portion of the endless belt 51 corresponding to the heat generation region H2 that extends between the first electrode portion 57 and the suspension roller 52 is sufficiently longer than the portion of the endless belt 51 corresponding to the heat generation region H1 (cf. FIGS. 1A and 1B). Accordingly, the surface temperature of the endless belt 51 did not reach 50qC or more and no effect on the toner T (the transparent toner) stored in the toner storage chamber 64 was observed. [0076] Further, since the moving bias applied to the suspension roller 52 and the fixing bias applied to the second electrode portion 58 were set to the same potential, the endless belt 51 at the portion corresponding to the region L defined by the suspension roller 52 and the second electrode portion does not generate heat (cf. FIGS. 1A and 1B). As a result, the endless belt 51 is cooled in the region L, so as to eliminate the influence on the toner layer forming portion D or the charging device disposed in the region L, and additionally to simplify the feeding part used for the generation and control of moving bias and fixing bias. [0077] Test Example 2 In a Test Example 2, the conditions were the same as in Test Example 1 with some exceptions in that the application conditions of the charging bias, the moving bias (or transfer bias), and the fixing bias were modified. [0078] With reference to FIGS. 7A and 7B, a DC component of +800 v was applied to the charged portion 592 and no charging bias was applied to the charged portions 591 and 593. As a result, the surface potential of the outer circumferential surface of the endless belt 51 at the portion corresponding to the charged portion 592 was +250 v and the surface potential at the portions corresponding to the charged portions 591 and 593 was r0 v. [0079] As a moving bias, a DC component of +70 v was applied to the toner carrier 61 and a DC component of +20 v was applied to the suspension roller 52. As a result of applying the DC component of +20 v to the suspension roller 52, the surface potential of the outer circumferential surface of the endless belt 51 at the portions corresponding to the charged portions 591 and 593 was +270 v and the surface potential at the portion corresponding to the charged portion 592 changed to +15 v. [0080] A portion of the endless belt 51 corresponding to the charged portion 592 causes a potential difference of +200 v with respect to the moving bias of +70 v applied to the toner carrier 61, which causes a negatively charged toner to be transferred so that a toner layer is formed. In this case, since the surface potential of the portion corresponding to the charged portion 592 which is the destination of the toner to be transferred, is the potential which is generated by the influence of the charging of the charging device 59 and the moving bias applied to the suspension roller 52, there is a variation in surface potential due to the uneven charging of the charging device 59. Therefore, although some layer thickness unevenness occurs in the toner layer on the endless belt 51, the unevenness is negligible in practical use. On the other hand, since the potential difference between the charged portions 591 and 593 with respect to the toner carrier 61 is -50 v, the negatively charged toner T (transparent toner) does not transfer to the endless belt 51 and is prevented from adhering to the endless belt 51. [0081] As a fixing bias, the first electrode portion 57 was grounded and a DC component of +20 v was applied to the second electrode portion 58. As a result, the surface temperature of the endless belt 51 of the portion corresponding to the heat generation region H1 reached 180qC, but the surface temperature of the endless belt 51 of the portion corresponding to the heat generation region H2 was less than 50qC. Further, since the moving bias applied to the suspension roller 52 and the fixing bias applied to the second electrode portion are the same potential, heat is not generated at the portion corresponding to the region L of the endless belt 51. [0082] The toner layer formed on the portion corresponding to the charged portion 592 of the endless belt 51 is transferred and fixed to the recording material when passing through the contact region between the pressing member 56 and the pressing roller 55 while being in close contact with the recording material to which the color toner image is transferred in advance. As a result, a color print having a transparent layer on the surface of the color image was obtained. In addition, no stains or the like due to the transparent toner were found at the portions corresponding to the charged portions 591 and 593 of the endless belt 51. Further, the heat generated by the endless belt 51 did not affect the toner T (transparent toner) stored in the toner storage chamber 64 or other parts constituting the heat treatment device 1B. [0083] Test Example 3 With reference to FIGS. 8A and 8B, in a Test Example 3, the cartridge storing the toner T (transparent toner) used in Test Example 1 was replaced with a cartridge storing a positively charged invisible toner (particle size; 5.8 Pm, Tg; 61qC). The cartridge storing the invisible toner differs in terms of the type of toner contained, and the other components are similar to those in Test Example 1. [0084] The identification information storage unit of the cartridge storing the invisible toner stores the application conditions of the charging bias, the moving bias (or transfer bias), and the fixing bias according to the invisible toner. As a charging bias, the elimination of static electricity was performed on the portion of the charging device 59 forming the toner layer and the voltage applied to the portion that does not form the toner layer was +800 v. As a moving bias, the voltage applied to the suspension roller 52 was -20 v and the voltage applied to the toner carrier 61 was +180 v. As a fixing bias, the first electrode portion 57 was grounded and the voltage applied to the second electrode portion 58 was -20 v. [0085] In the modified test machine used in Test Example 3, the bias application conditions were changed and set based on the application conditions stored in the identification information storage unit. After the elimination of static electricity of the endless belt 51, a DC component of +800 v was applied to the portions where the toner layer was not formed (corresponding to the charged portions 591 and 593). As a result, the surface potential of the outer circumferential surface of the endless belt 51 at the portion provided with the toner layer (corresponding to the charged portion 592) was r0 v and the surface potential at the portion not provided with the toner layer was +250 v. [0086] As a moving bias, a DC component of +180 v was applied to the toner carrier 61 and a DC component of -20 v was applied to the suspension roller 52. As a result of applying the DC component of -20 v to the suspension roller 52, the surface potential of the outer circumferential surface of the endless belt 51 at the portion provided with the toner layer was -15 v and the surface potential at the portion not provided with the toner layer changed to +230 v. [0087] The portion provided with the toner layer on the endless belt 51 causes a potential difference of -195 v with respect to the moving bias of +180 v applied to the toner carrier 61, such that the positively charged invisible toner is transferred so as to form the toner layer. In this case, since the surface potential of the portion forming the toner layer is the potential caused by the influence of the elimination of static electricity by the charging device 59 and the moving bias applied to the suspension roller 52, there is relatively little variation in surface potential. Therefore, the toner layer formed on the endless belt 51 has a uniform layer thickness. On the other hand, since the potential difference at the portion not provided with the toner layer is +50 v, the positively charged invisible toner is not transferred to the endless belt 51 and is prevented from adhering thereto. [0088] As a fixing bias, the first electrode portion 57 was grounded and a DC component of -20 v was applied to the second electrode portion 58. As a result, the surface temperature of the endless belt 51 of the portion corresponding to the heat generation region H1 reached 180qC, but the surface temperature of the endless belt 51 of the portion corresponding to the heat generation region H2 did not reach 50qC or more. Further, since the moving bias applied to the suspension roller 52 and the fixing bias applied to the second electrode portion 58 are the same potential, heat is not generated at the portion corresponding to the region L of the endless belt 51. [0089] The toner layer formed on the endless belt 51 was transferred and fixed to the recording material when passing through the contact region of the pressing member 56 and the pressing roller 55 while being in close contact with the recording material to which the color toner image was transferred in advance. As a result, a color print was obtained in which an image with invisible toner was added to the surface of the color image. When the obtained color print was irradiated with black light, various images that could not be seen with normal light appeared. In this case, the image appearing in the black light was uniform and no stains due to the invisible toner were observed in the parts other than the image appearing in the black light. Further, the heat generated by the endless belt 51 did not affect the invisible toner stored in the toner storage chamber 64 or other parts constituting the heat treatment device 1B. [0090] Test Example 4 With reference to FIGS.9A and 9B, in a Test Example 4, the conditions were similar to those of Test Example 3 with some exceptions in that the application conditions of the charging bias, the moving bias, and the fixing bias were modified. [0091] In the endless belt 51, a DC component of -600 v was applied to the portion provided with the toner layer (corresponding to the charged portion 592) after the elimination of static electricity by the charging device 59. As a result, the surface potential of the outer circumferential surface of the endless belt 51 at the portion provided with the toner layer was -250 v and the surface potential at the portion not provided with the toner layer was r0 v. [0092] As a moving bias (or transfer bias), a DC component of -70 v was applied to the toner carrier 61 and a DC component of -20 v was applied to the suspension roller 52. As a result of applying the DC component of -20 v to the suspension roller 52, the surface potential of the outer circumferential surface of the endless belt 51 at the portion provided with the toner layer was -270 v and the surface potential at the portion not provided with the toner layer changed to -15 v. [0093] The portion provided with the toner layer on the endless belt 51 causes a potential difference of -200 v with respect to the moving bias of -70 v applied to the toner carrier 61, such that the positively charged invisible toner is transferred so as to form the toner layer. In this case, since the surface potential of the portion forming the toner layer is the potential generated by the influence of the charging of the charging device 59 and the moving bias applied to the suspension roller, there is a variation in surface potential due to uneven charging of the charging device. Therefore, the toner layer on the endless belt 51 had some layer thickness unevenness. On the other hand, since the potential difference of the portion not provided with the toner layer with respect to the toner carrier 61 is +55 v, the positively charged invisible toner does not transfer to the endless belt 51 and is prevented from adhering thereto. As a fixing bias, the first electrode portion 57 was grounded and a DC component of -20 v was applied to the second electrode portion 58. As a result, the surface temperature of the endless belt 51 at the portion corresponding to the heat generation region H1 reached 180qC, but the surface temperature of the endless belt 51 at the portion corresponding to the heat generation region H2 did not reach 50qC or more. Further, since the moving bias applied to the suspension roller 52 and the fixing bias applied to the second electrode portion 58 are the same potential, heat is not generated at the portion corresponding to the region L of the endless belt 51. [0094] The toner layer formed on the endless belt 51 was transferred and fixed to the recording material when passing through the contact region of the pressing member 56 and the pressing roller 55 while being in close contact with the recording material to which the color toner image was transferred in advance. As a result, a color print was obtained in which an image with invisible toner was added to the surface of the color image. When the obtained color print was irradiated with black light, various images that could not be seen with normal light appeared. The image that appeared in black light had some unevenness, but was at an acceptable level. No stains due to invisible toner were found in the parts other than the image that appeared in the black light. Further, the heat generated by the endless belt 51 did not affect the invisible toner stored in the toner storage chamber 64 or other parts constituting the heat treatment device 1B. [0095] It is to be understood that not all aspects, advantages and features described herein may necessarily be achieved by, or included in, any one particular example. Indeed, having described and illustrated various examples herein, it should be apparent that other examples may be modified in arrangement and detail is omitted.

Claims

CLAIMS 1. A heat treatment device comprising: a toner-layer-forming device to supply toner; and an endless belt including a toner-layer-forming portion to receive a layer of toner from the toner-layer-forming device, and a transfer-and-fixing portion to transfer and fix the layer of toner to a medium, the endless belt to generate heat in the transfer-and-fixing portion, in response to an electric power supply, during a rotation of the endless belt.

2. The heat treatment device according to claim 1, wherein the toner-layer-forming device includes: a toner storage chamber to store a toner, a toner carrier that is rotatable to carry and convey the toner from the toner storage chamber, and a toner regulation member to limit a layer thickness of the toner carried on the toner carrier, wherein the heat treatment device comprises a suspension roller to support the endless belt, wherein the suspension roller faces the toner carrier so that the endless belt extends between the suspension roller and the toner carrier, and the toner-layer-forming portion of the endless belt is formed between the toner carrier and the suspension roller, to receive the layer of toner in response to a moving bias that causes the toner carried on the toner carrier to transfer onto the endless belt.

3. The heat treatment device according to claim 2, comprising: a first electrode and a second electrode that contact a base layer of the endless belt, wherein the first electrode and the second electrode extend in an axial direction of the endless belt, and are spaced apart in a rotational direction of the endless belt, the transfer-and-fixing portion to transfer and fix the layer of toner to the medium when a fixing bias that generates heat in the endless belt, is applied between the first electrode and the second electrode.

4. The heat treatment device according to claim 3. the moving bias to operate as the fixing bias.

5. The heat treatment device according to claim 4, wherein the fixing bias includes a first fixing bias and a second fixing bias that is set to the same potential as the first fixing bias, the first electrode to be grounded, the second electrode to receive the first fixing bias, and the suspension roller to receive the second fixing bias.

6. The heat treatment device according to claim 3, comprising: a pressing member to extend in the axial direction of the endless belt; and a pressure roller facing the pressing member, so that the endless belt extends between the pressing member and the pressure roller, wherein a contact region of the endless belt that contacts the pressure roller forms the transfer-and fixing portion and wherein the transfer-and-fixing portion of the endless belt extends between the first electrode and the second electrode, in the rotational direction of the endless belt.

7. The heat treatment device according to claim 3, comprising: a charging device facing the endless belt, wherein a charged portion is formed between the charging device and the endless belt to control a charged state of an outer surface layer of the endless belt when a charging bias is applied to the charging device.

8. The heat treatment device according to claim 7, the charging device to eliminate static electricity from the outer surface layer of the endless belt.

9. The heat treatment device according to claim 7, wherein any one among the fixing bias, the moving bias, and the charging bias is to be generated by a DC voltage.

10. The heat treatment device according to claim 7, wherein the moving bias includes a first moving bias to be applied to the toner carrier and a second moving bias to be applied to the suspension roller, wherein a difference between a bias potential of the first moving bias applied to the toner carrier and a surface potential of an outer surface of the endless belt is a polarity opposite to a charging polarity of the toner forming the layer of toner on the endless belt, and wherein the surface potential of the outer surface of the endless belt is selected from the group consisting of: a first surface potential of the outer surface of the endless belt generated by applying a charging bias to the charging device and by applying the second moving bias to the suspension roller, and a second surface potential of the outer surface of the endless belt generated by eliminating static electricity via the charging device and by applying the second moving bias to the suspension roller.

11. The heat treatment device according to claim 10, the bias potential associated with the first moving bias to be set according to the second surface potential of the outer surface of the endless belt, to a potential that causes the layer of toner to transfer to the endless belt.

12. The heat treatment device according to claim 1, wherein the endless belt includes a base layer formed of a nanocomposite material obtained by dispersing carbon filler, and a non-conductive outer surface layer.

13. The heat treatment device according to claim 1, comprising: a container that houses the toner-layer-forming device and the endless belt, wherein the container is removably attachable to an electrophotographic image forming device, as a replaceable process cartridge.

14. An electrophotographic image forming device comprising: a heat treatment device forming a fixing device of the electrophotographic image forming device, wherein the heat treatment device includes: a toner-layer-forming device to supply toner; and an endless belt including a toner-layer-forming portion to receive a layer of toner from the toner-layer-forming device, and a transfer-and-fixing portion to transfer and fix the layer of toner to a medium, the endless belt to generate heat in the transfer-and-fixing portion, in response to an electric power supply, during a rotation of the endless belt.

15. A handy-type heat treatment device comprising: a toner-layer-forming device to supply toner; and an endless belt including a toner-layer-forming portion to receive a layer of toner from the toner-layer-forming device, and a transfer-and-fixing portion to be pressed against a surface of an object to be treated, so as to transfer and fix the layer of toner to the surface, the endless belt to generate heat in the transfer-and-fixing portion, in response to an electric power supply, during a rotation of the endless belt, the endless belt to rotate in accordance with a movement of the handy-type heat treatment device relative to the surface of the object when the transfer-and-fixing portion is pressed against the surface, so as to receive the layer of toner from the toner-layer-forming device and to transfer and to fix the layer of toner to the surface of the object while the endless belt is rotationally moved in a pressed state.