Fixing device and image forming device

Abstract

The present invention relates to a fixing device and an image forming device. The fixing device comprises: a hollow rotating body; a planar heating element arranged inside the rotating body, extending in a width direction perpendicular to the conveying direction of a recording medium conveyed accompanying the rotation of the rotating body, and heating the rotating body; and a plurality of heat-conducting components, which are in contact with the surface of the planar heating element on the opposite side of the contact surface of the rotating body, and are arranged at intervals in at least one of the width direction and the conveying direction, so that the heat of the planar heating element is conducted in the width direction, and when viewed from the conveying direction in a plane-unfolded state, the plurality of heat-conducting components are arranged so that a portion of one heat-conducting component overlaps a portion of another heat-conducting component adjacent to the one heat-conducting component.

Description

Technical Field

[0001] The present disclosure relates to a fixing device and an image forming device. Background Art

[0002] Japanese Patent Gazette No. 2016-71284 discloses an image heating device, which comprises: a heating component, which has a slender substrate and a resistive heating element formed on the substrate along the length direction and generates heat when electricity is applied; an endless belt, the inner circumference of which contacts and slides with the first surface of the heating component and can rotate around the heating component; a heat conduction component, which contacts the second surface of the heating component and has a higher thermal conductivity than the substrate; a contact component, which contacts the endless belt; and a rotating body, which contacts the outer surface of the endless belt to form a clamping portion, and the recording material carrying an image is conveyed by the rotation of the rotating body while being clamped and heated, wherein, in a direction perpendicular to the conveying direction of the recording material within the conveying path surface of the recording material, in an area of ​​the passage area of ​​the recording material with the maximum width dimension that can be conveyed by the image heating device, a first area where the heat conduction component contacts the heating component is wider than a second area where the heat conduction component does not contact, and in the circumferential direction of the endless belt, a third area where the contact component contacts the endless belt at least includes the second area. Summary of the invention

[0003] The object of the present disclosure is to provide a fixing device and an image forming device, in which, in a structure having a planar heating element and a plurality of heat-conductive components in contact with a surface on a side of the planar heating element opposite to a rotating body, generation of a temperature difference in a width direction of the planar heating element can be suppressed compared to a structure in which respective end faces of adjacent heat-conductive components are along a conveying direction, and the planar heating element heats a plurality of recording media of different sizes in a width direction perpendicular to the conveying direction in a conveying state.

[0004] According to a first aspect of the present disclosure, there is provided a fixing device, wherein the fixing device comprises:

[0005] A hollow rotating body;

[0006] a planar heating element disposed inside the rotating body and extending in a width direction perpendicular to a conveyance direction of a recording medium conveyed along with the rotation of the rotating body, for heating the rotating body; and

[0007] A plurality of heat-conducting components are in contact with the surface of the planar heat generating element on the opposite side of the contact surface of the rotating element, and are arranged at intervals in at least one of the width direction and the conveying direction so that the heat of the planar heat generating element is conducted in the width direction. When observed from the conveying direction in a plane unfolded state, the plurality of heat-conducting components are arranged so that a portion of one of the heat-conducting components overlaps a portion of another heat-conducting component adjacent to the one heat-conducting component.

[0008] According to the second aspect of the present disclosure, the lengths of the adjacent heat conductive members in the conveying direction are set to be the same, and the adjacent heat conductive members entirely overlap when viewed from the width direction.

[0009] According to the third aspect of the present disclosure, when viewed from the thickness direction perpendicular to the conveying direction and the width direction, the opposing edges of the adjacent heat conductive members that face each other extend in the intersecting direction that intersects the conveying direction.

[0010] According to a fourth aspect of the present disclosure, the number of the plurality of heat conductive members is an odd number of 3 or more, and when viewed from the thickness direction, the heat conductive member located at the center in the width direction among the plurality of heat conductive members has an outer shape of an isosceles trapezoid.

[0011] According to the fifth aspect of the present disclosure, when viewed from the thickness direction perpendicular to the conveyance direction and the width direction, at least a portion of mutually opposing edges of the adjacent heat conductive members face each other in the conveyance direction.

[0012] According to the sixth embodiment of the present disclosure, a recessed portion that is recessed in the width direction when viewed from the thickness direction is formed on the end surface in the width direction of one of the adjacent heat-conducting components, and a protruding portion that protrudes in the width direction when viewed from the thickness direction is formed on the end surface in the width direction of the other adjacent heat-conducting component, and the protruding portion is inserted into the recessed portion.

[0013] According to the seventh aspect of the present disclosure, a plurality of corners are formed at mutually opposing locations of the adjacent heat conductive members, and when viewed in a thickness direction perpendicular to the conveying direction and the width direction, the angles of the plurality of corners are all greater than 90 degrees.

[0014] According to an eighth aspect of the present disclosure, there is provided an image forming apparatus comprising: an image forming unit that forms a developer image on a recording medium; and a fixing device that heats and pressurizes the developer image to fix the developer image to the recording medium.

[0015] Effects of the Invention

[0016] According to the first scheme, in a structure having a planar heating element and a plurality of heat-conducting components in contact with the surface of the planar heating element on the side opposite to the rotating body side, the generation of temperature differences in the width direction of the planar heating element can be suppressed compared to a structure in which the respective end faces of adjacent heat-conducting components are along the conveying direction, and the planar heating element heats a plurality of recording media of different sizes in the width direction perpendicular to the conveying direction in a conveying state.

[0017] According to the second aspect, compared with a structure in which only a part of each of the plurality of heat-conductive members faces each other in the width direction, it is possible to suppress a temperature difference in the width direction of the recording medium.

[0018] According to the third aspect, the heat conducting member can be manufactured more easily than in a structure in which the facing surface is formed in a step shape.

[0019] According to the fourth aspect, the heat conducting members can be arranged symmetrically with respect to the center in the width direction of the planar heat generating element.

[0020] According to the fifth aspect, compared with a structure in which the gaps between the plurality of heat conductive members extend in a direction intersecting the conveying direction, the gaps in the conveying direction can be made smaller.

[0021] According to the sixth aspect, compared with a structure in which the protrusion is not inserted into the recess, it is possible to suppress the heat conduction member from being largely displaced in the conveyance direction during manufacture of the fixing device.

[0022] According to the seventh aspect, deformation of the heat conducting member can be suppressed compared to a structure in which at least one corner is an acute angle.

[0023] According to the eighth aspect, compared with a structure in which the gaps between adjacent heat-conductive members extend along the conveying direction, it is possible to suppress image defects caused by a temperature difference in the width direction of the planar heat generating element. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a front view of the image forming apparatus according to the first embodiment.

[0025] Figure 2 It is a longitudinal sectional view of the fixing device according to the first embodiment.

[0026] Figure 3A It is a perspective view of a part of the planar heating element and two heat conducting members according to the first embodiment.

[0027] Figure 3B This is a plan view of two heat conducting members according to a modification of the first embodiment when viewed from the thickness direction.

[0028] Figure 4A It is a plan view showing the arrangement state of two heat conducting members according to the first embodiment.

[0029] Figure 4B This is a side view showing a superimposed state of two heat conducting members according to the first embodiment.

[0030] Figure 5 It is a plan view showing the arrangement of the resistor of the planar heating element, a plurality of heat-conductive members, and paper according to the first embodiment.

[0031] Figure 6 It is an explanatory diagram showing the arrangement relationship among a plurality of heat conducting members, thermistors, and thermostats according to the first embodiment.

[0032] Figure 7 It is an explanatory diagram showing a state of heat conduction from the planar heat generating element to the heat conducting member according to the first embodiment.

[0033] Fig. 8A This is a graph showing the difference in uneven glossiness of an image in the width direction in the fixing device according to the first embodiment.

[0034] Figure 8B This is a graph showing the temperature distribution in the transport direction at a portion of the planar heat generating element in contact with the central portion of the heat conducting member according to the first embodiment.

[0035] Figure 8C This is a graph showing the temperature distribution in the transport direction at a portion of the planar heat generating element in contact with the end portion of the heat conducting member according to the first embodiment.

[0036] Fig. 9 It is a plan view showing the arrangement state of two heat conducting members according to the second embodiment.

[0037] Fig.10 This is a graph showing the relationship between the length of the gap between two heat conducting members and the temperature difference in the conveyance direction of the planar heat generating element according to the second embodiment.

[0038] Fig.11 It is a plan view showing the arrangement state of two heat conducting members according to the third embodiment.

[0039] Fig.12 It is a plan view showing an arrangement state of two heat conducting members according to a modification of the third embodiment.

[0040] Fig.13 It is a plan view showing the arrangement state of two heat conducting members according to the fourth embodiment.

[0041] Fig.14A It is a plan view showing the arrangement state of two heat conducting members according to the comparative example.

[0042] Fig. 14B This is a graph showing the difference in uneven glossiness of an image in the width direction in a fixing device according to a comparative example.

[0043] Fig. 14C This is a graph showing the temperature distribution in the transport direction at a portion of the planar heat generating element in contact with the heat conducting member according to the comparative example.

[0044] Fig.14D This is a graph showing the temperature distribution in the conveying direction in the gap portion of the planar heat generating element according to the comparative example which is not in contact with the heat conducting member. DETAILED DESCRIPTION

[0045] [First embodiment]

[0046] As examples of the image forming apparatus and the fixing device, an image forming apparatus 10 and a fixing device 30 according to the first embodiment will be described.

[0047] 〔Overall structure〕

[0048] Figure 1 An image forming device 10 is shown. The image forming device 10 is configured to include a storage unit 12 that stores paper P; a conveying unit 14 that conveys paper P; an image forming unit 16 that forms a toner image G on the paper P; a control unit 18 that controls the operation of each unit of the image forming device 10; and a fixing device 30. In the following description, with respect to the image forming device 10, the height direction is referred to as the "device height direction", the depth direction is referred to as the "device depth direction", and the left and right direction is referred to as the "device width direction". The device height direction, the device depth direction, and the device width direction are directions perpendicular to each other.

[0049] Paper P is an example of a recording medium. As an example of paper P, in this embodiment, two types of paper PA and PB having different lengths (widths) in the device width direction are used. In the following description, paper with a narrower width is referred to as paper PA, and paper with a width wider than the width of paper PA is referred to as paper PB. In addition, the length of paper PA in the device width direction is set to L1 [mm], and the length of paper PB in the device width direction is set to 2 [mm] (refer to Figure 5 ). The toner image G is an example of a developer image.

[0050] The storage section 12 stores the paper sheets PA and PB. The conveying section 14 conveys the paper sheets P from the storage section 12 toward the upper side in the height direction of the device along the conveying path T. The image forming section 16 is an example of an image forming unit. In addition, as an example, the image forming section 16 is configured to use a single color or a plurality of color toners to perform the charging, exposure, development, and transfer processes of a known electronic photography method to form a toner image G on the paper sheet P.

[0051] 〔Main structure〕

[0052] Next, the fixing device 30 will be described.

[0053] Figure 2 The fixing device 30 shown has a housing 32 constituting the main body of the device; a heating unit 40, which is provided in the housing 32 and arranged on one side of the conveying path T for conveying the paper P; and a pressure roller 34, which is provided in the housing 32 and arranged on the other side of the conveying path T. As an example, the direction in which the conveying path T extends (the conveying direction of the paper P) coincides with the height direction of the device. In addition, in the fixing device 30, a method of conveying the paper P by aligning the center of the conveying path T and the center of the paper P in the depth direction of the device is adopted, that is, a center positioning method. The fixing device 30 heats and pressurizes the toner image G so that the toner image G is fixed to the paper P.

[0054] <Pressure roller>

[0055] The pressure roller 34 is an example of a pressure member, and includes a shaft member 35 with the device depth direction as the axial direction, an elastic layer 36, and a release layer 37. The shaft member 35 is supported by a bearing (not shown) and driven to rotate by a motor (not shown). Furthermore, the shaft member 35 is pressed toward the heating unit 40 side arranged on one side of the conveying path T by a pressing member including a spring (not shown).

[0056] <Heating section>

[0057] As an example, the heating unit 40 includes a support frame 42, a holding member 44, a belt 46 as an example of a rotating body, a planar heating element 48, a plurality of heat conducting members 56, and a detection unit 62. In addition, in a non-passing state of the paper P, a portion where the outer peripheral surface of the belt 46 contacts the outer peripheral surface of the pressure roller 34 is referred to as a nip portion NP. The paper P is transported with the rotation of the belt 46.

[0058] (Support frame)

[0059] The support frame 42 is a member that is long in the depth direction of the device. When viewed from the depth direction of the device, the cross-sectional shape of the support frame 42 is a U-shape that opens toward the pressure roller 34. In addition, both ends of the support frame 42 in the depth direction of the device are supported by the housing 32, and the central portion is arranged inside the belt 46 described later.

[0060] In the following description, the length direction of the support frame 42 is referred to as the Z direction. The Z direction is an example of a width direction. In addition, the conveying direction that is perpendicular to the Z direction and conveys the paper P in the fixing device 30 is referred to as the X direction. Furthermore, the direction that is perpendicular to the X direction and the Z direction and constitutes the thickness direction of the planar heating element 48 described later is referred to as the Y direction. In this embodiment, as an example, the Z direction is consistent with the depth direction of the device, the X direction is consistent with the height direction of the device, and the Y direction is consistent with the width direction of the device. That is, the X direction, the Y direction, and the Z direction are directions perpendicular to each other.

[0061] When distinguishing between the positive and negative components of the X-axis direction, they are called the upper side and the lower side. When distinguishing between one side and the other side relative to the center in the Y direction, they are called the heating side and the pressure-applying side. When distinguishing between one side and the other side relative to the center in the Z direction, they are called the back side and the near front side.

[0062] (Retaining parts)

[0063] As an example, the holding member 44 is a member made of polyimide resin that is long in the Z direction. The holding member 44 is attached to a portion of the support frame 42 on the pressure-applying side, and holds a planar heating element 48 and a plurality of heat-conducting members 56 described later in the X direction.

[0064] (bring)

[0065] As an example of a hollow rotating body, the belt 46 is a member made of polyimide resin with a fluorine coating applied to the surface (outer peripheral surface), and is formed into a cylindrical (ring-shaped) shape when viewed from the Z direction. Both ends of the belt 46 in the Z direction are rotatably supported by cover members (not shown). Furthermore, the belt 46 rotates in the direction of arrow R in the figure along with the rotation of the pressure roller 34 (driven by the rotation of the pressure roller 34), thereby conveying the paper P in the X direction. The length of the belt 46 in the Z direction is set to L3 [mm] (refer to Figure 5 ). The length L3 is longer than the length L2 ( Figure 5 Reference) length.

[0066] (Surface heating element)

[0067] When viewed from the Y direction, Figure 5 The planar heating element 48 shown is formed into a rectangular plate shape that is long in the Z direction and short in the X direction. The Z direction is an example of the width direction of the planar heating element 48. In addition, the planar heating element 48 has a base material 49 as a main body, a pair of electrodes 51 for voltage application, a resistor 52, and an insulating film 53.

[0068] The substrate 49 is formed into a rectangular plate shape that is long in the Z direction. The length of the substrate 49 in the Z direction is longer than the length L3 described above. The length of the substrate 49 in the X direction is shorter than the length of the support frame 42 in the X direction. As an example, the thickness of the substrate 49 is set to 0.7 [mm]. In addition, as an example, the substrate 49 is composed of an alumina molded body having insulating properties. In this embodiment, the insulating property refers to a conductivity of 1×10 －10 [S / m] or less. As an example, the heat transfer characteristics of the substrate 49 are set to be isotropic. As an example, the thermal conductivity of the substrate 49 is 41 [W / mK]. The thermal conductivity described in this embodiment is based on JISR2616:2001.

[0069] The resistor 52 is formed into a U-shape that is longer in the Z direction when viewed from the Y direction. In addition, the resistor 52 has a linear heating portion 52A that is arranged on the lower side in the X direction (upstream side in the conveying direction) and extends in the Z direction, and a linear heating portion 52B that is arranged on the upper side in the X direction (downstream side in the conveying direction) and extends in the Z direction. The heating portion 52A and the heating portion 52B are arranged approximately parallel to each other along the Z direction, with a gap in the X direction. The length of the heating portion 52A in the Z direction is the same as the length of the heating portion 52B in the Z direction, which is longer than the above-mentioned length L2.

[0070] Furthermore, the resistor 52 is covered with an insulating film 53 formed of a heat-resistant resin material. As an example, the height of the surface of the insulating film 53 is aligned with the height of the surface of the substrate 49 to be almost the same. In addition, the resistor 52 and the pair of electrodes 51 are connected. Here, by passing a current (energization) from a power source (not shown) through the pair of electrodes 51 to the resistor 52, the heat generating portions 52A and 52B generate heat.

[0071] like Figure 2 As shown, the planar heating element 48 is arranged on the inner side of the belt 46 with the Y direction as the thickness direction, and is held by the holding member 44. Specifically, the planar heating element 48 is arranged on the heating side in the Y direction relative to the belt 46 in the clamping portion NP, and is in contact with the inner peripheral surface of the belt 46. The surface of the planar heating element 48 in contact with the belt 46 is referred to as a contact surface 54. In addition, the surface of the planar heating element 48 on the side opposite to the belt 46 side in the Y direction is referred to as a back surface 55. The planar heating element 48 clamps the belt 46 and the paper P together with the pressure roller 34 in the clamping portion NP, and applies pressure and heats the belt 46 and the paper P.

[0072] (Heat conduction components)

[0073] like Figure 5 As shown in FIG. 1 , as an example, the fixing device 30 includes five heat conducting members 56. Figure 55 heat-conducting components 56 are shown in the state when they are unfolded in the X-Z plane and observed from the Y direction. The five heat-conducting components 56 are components that are in contact with the back surface 55 and conduct the heat conducted from the planar heating element 48 in the Z direction. As an example, they are made of graphite. The heat conductivity of the heat-conducting component 56 in the Z direction is higher than the heat conductivity of the substrate 49 in the Z direction. As an example, the thickness of the heat-conducting component 56 is set to 0.3 [mm].

[0074] like Figure 3A As shown, the heat conducting member 56 is formed in a flat plate shape with the Y direction as the thickness direction. In addition, as an example, the outer shape of the heat conducting member 56 when viewed from the Y direction is a parallelogram. The heat conducting member 56 overlaps with the back surface 55 of the planar heat generating element 48.

[0075] As an example, Figure 5 The heat conductivity of the heat conducting member 56 in the in-plane direction is shown to be 1000 [W / mK]. As an example, the heat conductivity of the heat conducting member 56 in the thickness direction is 15 [W / mK]. That is, in the heat conducting member 56, more heat is conducted in the Z direction than in the Y direction.

[0076] As an example, five heat-conducting components 56 are formed by dividing a heat-conducting component (not shown) which is long in the Z direction into five components with the same size and shape in the Z direction. The reason why the heat-conducting component is divided into five components (multiple components are arranged) is to suppress deformation of the heat-conducting component caused by the difference in their respective thermal expansion coefficients when one long heat-conducting component is brought into contact with one long planar heating element 48.

[0077] When distinguishing the five heat conducting members 56, they are marked with A, B, C, D, and E in order from the front side in the Z direction. The heat conducting member 56C is arranged so as to contact the center portion in the Z direction of the planar heating element 48. The heat conducting member 56C is arranged within the range where all the paper sheets P pass.

[0078] The position corresponding to the approximate center in the Z direction of the heat conducting member 56B is aligned with the position of the front side end in the Z direction of the paper PA. The position corresponding to the approximate center in the Z direction of the heat conducting member 56D is aligned with the position of the back side end in the Z direction of the paper PA. The front side end in the Z direction of the paper PB is located at a position closer to the front side than the center in the Z direction of the heat conducting member 56A. The back side end in the Z direction of the paper PB is located at a position further back than the center in the Z direction of the heat conducting member 56E.

[0079] The heat conducting members 56A, 56B, 56C, 56D, and 56E have the same structure. Therefore, hereinafter, the heat conducting members 56A and 56B will be described, and the description of the heat conducting members 56C, 56D, and 56E will be omitted.

[0080] Figure 4A The heat conducting component 56A and the heat conducting component 56B are shown in a state when they are unfolded in the X-Z plane and observed from the Y direction. The heat conducting component 56A and the heat conducting component 56B are arranged with a gap (gap 57) in the Z direction and are adjacent to each other in the Z direction. Furthermore, a part of the inner side end in the Z direction of the heat conducting component 56A and a part of the front side end in the Z direction of the heat conducting component 56B are arranged so as to overlap in the X direction when viewed from the X direction. As an example, the overlapping part is located closer to the front side in the Z direction than the front side end in the Z direction of the paper PA and closer to the inner side in the Z direction than the front side end in the Z direction of the paper PB. In addition, the lengths in the X direction of the heat conducting component 56A and the heat conducting component 56B are set to be the same length, and overlap in the entire X direction (from one end to the other end) when viewed from the Z direction.

[0081] When viewed from the Y direction, the gap 57 extends linearly along the intersecting direction (hereinafter referred to as the C direction) intersecting the X direction. In addition, when viewed from the Y direction, the direction perpendicular to the C direction is referred to as the D direction. Here, the side surface of the heat conducting component 56A that forms the gap 57 is referred to as the opposing surface 58A. In addition, the side surface of the heat conducting component 56B that forms the gap 57 is referred to as the opposing surface 58B. The opposing surface 58A and the opposing surface 58B are examples of opposing edges that are opposed to each other. Therefore, when viewed from the Y direction, the opposing surface 58A and the opposing surface 58B extend in the C direction respectively, and are opposed to each other with the gap 57 in between in the D direction.

[0082] When observing the heat conducting components 56A and 56B from the Y direction, the position of the opposing surface 58A that constitutes the inner end in the Z direction (the vertex of the acute angle of the parallelogram) is indicated by point A. Point A is located on the upper surface 59A of the heat conducting component 56A located on the upper side in the X direction. In addition, the line passing through point A and along the X direction is called the imaginary line V1. Furthermore, the surface of the heat conducting component 56B located on the lower side in the X direction is called the lower surface 59B. The intersection of the imaginary line V1 and the opposing surface 58B is indicated by point E, and the intersection of the imaginary line V1 and the lower surface 59B is indicated by point F. Similarly, the position of the opposing surface 58B that constitutes the near front end in the Z direction (the vertex of the acute angle of the parallelogram) is indicated by point D. Point D is located on the lower surface 59B. In addition, the line passing through point D and along the X direction is called the imaginary line V2. The intersection point of the imaginary line V2 and the facing surface 58A is indicated by point B, and the intersection point of the imaginary line V2 and the upper surface 59A is indicated by point C.

[0083] Here, regarding the heat conducting member 56A and the heat conducting member 56B, when viewed from the X direction, the portion located between the imaginary line V1 and the imaginary line V2 in the Z direction (referred to as region N1) is an overlapping portion. When viewed from the Y direction, this portion is composed of the end S1 represented by the triangle ABC and the end S2 represented by the triangle DEF. In the heat conducting member 56A, heat conduction is performed from the end S1 to other portions. In the heat conducting member 56B, heat conduction is performed from the end S2 to other portions. In addition, the region N1 is located between the Z direction front side end of the paper PA and the Z direction front side end of the paper PB.

[0084] As an example, the length of the heat conducting member 56A in the X direction, the length of the heat conducting member 56B in the X direction, and the length of the planar heating element 48 in the X direction are set to be the same length. Furthermore, when viewed from the Y direction, as an example, the positions of the ends of the heat conducting member 56A and the heat conducting member 56B in the X direction are aligned with the positions of the ends of the planar heating element 48 in the X direction to be the same position.

[0085] Figure 4B The heat conducting member 56A and the heat conducting member 56B are shown in a state when they are developed in the X-Z plane and viewed from the X direction. As shown by the shadow, the end S1 of the heat conducting member 56A and the end S2 of the heat conducting member 56B overlap in the X direction. In other words, the end S1 and the end S2 are arranged so as to overlap when projected in the X direction.

[0086] (Detection Department)

[0087] Figure 6 Shown from the clamping portion NP ( Figure 2 The state when observing the heat-conducting components 56A, 56B, 56C, 56D, 56E and the detection unit 62 from the side (reference). As an example, the detection unit 62 is configured to include four thermistors 64A, 64B, 64C, 64D and one thermostat 66. Thermistor 64A detects the temperature of the heat-conducting component 56A. Thermistor 64B detects the temperature of the heat-conducting component 56B. Thermistor 64C detects the temperature of the heat-conducting component 56D. Thermistor 64D detects the temperature of the heat-conducting component 56E. When the temperature of the heat-conducting component 56C exceeds a preset set temperature, the thermostat 66 turns on the temperature of the planar heating element 48 (reference). Figure 2 ) is stopped from being energized, thereby suppressing the excessive temperature rise of the planar heating element 48.

[0088] [Comparative Example]

[0089] Fig.14A FIG. 2 shows a part of a fixing device 200 of a comparative example. The fixing device 200 is different only in that the fixing device 30 (see FIG. 20 ) is Figure 2) in the heat conducting member 56 (refer to Figure 2 ) are replaced by heat conducting components 200A, 200B.

[0090] The heat conducting members 200A and 200B are formed into rectangular shapes that are long in the Z direction and are arranged at intervals in the Z direction. The gap 202 between the heat conducting member 200A and the heat conducting member 200B extends linearly in the X direction. In other words, when viewed from the X direction, the heat conducting member 200A and the heat conducting member 200B do not overlap in the X direction. In the Z direction, the Z-direction center position of the heat conducting member 200A is referred to as position Z1, and the Z-direction center position of the gap 202 is referred to as position Z2.

[0091] exist Fig. 14B The heat conducting member 200A, the gap 202 and the heat conducting member 200B (all refer to Fig.14A ), the image gloss unevenness at each position, and the threshold value K indicating the upper limit value within the allowable range of the image gloss unevenness are shown as a graph G5. The image gloss is a characteristic value measured using a gloss meter based on the definition described in JIS standard Z8741. The image gloss unevenness is obtained by measuring the gloss of the toner image G after fixation with a gloss meter for the toner image G which is a rectangular shape long in the Z direction, and obtaining the difference between the maximum and minimum gloss values ​​in the X direction for each position in the Z direction.

[0092] In the fixing device 200 of the comparative example, the image gloss unevenness is lower than the threshold value K at the position Z1 and the like, but is larger than the threshold value K at the position Z2. This is considered to be because heat conduction in the Z direction can be performed by the heat conduction member 200A at the position Z1, but the heat conduction members 200A and 200B do not exist at the position Z2, so that heat conduction from other parts is insufficient, and the temperature of a part of the planar heat generating element 48 in the X direction is lower than that of other parts.

[0093] Fig. 14C The position Z1 is shown in FIG. Fig.14A ) in the X direction and the temperature of the planar heating element 48. Since the heat conducting member 200A (see Fig.14A ), so even if the position in the X direction changes, the temperature of the planar heating element 48 is unlikely to differ.

[0094] Fig.14D The display shows the position Z2 (refer to Fig.14A) and the temperature of the planar heating element 48. At position Z2, since there is no heat conducting member 200A, the heat supply in the Z direction to the planar heating element 48 is reduced, which is different from the temperature at position Z1 (graph G6 (refer to Fig. 14C )) is lower than that of the planar heating element 48. In addition, the resistor 52 (see Figure 5 ) area, the temperature becomes locally high.

[0095] 〔effect〕

[0096] Next, operations of the fixing device 30 and the image forming apparatus 10 according to the first embodiment will be described.

[0097] exist Figure 7 In the fixing device 30 shown, the planar heating element 48 generates heat by being energized, thereby heating the belt 46. Then, the paper PA with the toner image G formed thereon enters between the belt 46 and the pressure roller 34 (the nip portion NP), whereby the toner image G is heated and pressurized and fixed to the paper PA. The paper PA with the toner image G fixed thereon is discharged from the nip portion NP as the pressure roller 34 and the belt 46 rotate.

[0098] Heat Q is supplied to the paper PA and the toner image G at a portion of the planar heating element 48 in the Z direction and located in the paper passing area W1 of the paper PA when viewed from the X direction, so that the temperature of this portion is lowered compared to the temperature immediately before fixing. In order to eliminate the local temperature drop of the planar heating element 48, the planar heating element 48 is energized, so that the heating amount of the planar heating element 48 as a whole is increased.

[0099] On the other hand, in the non-paper-passing area W2 which is a part of the planar heating element 48 in the Z direction and is located outside the paper-passing area W1 of the paper PA in the Z direction when viewed from the X direction, there is no paper PA and the toner image G, and it is difficult to consume the heat Q. Therefore, the temperature of the planar heating element 48 becomes higher than the temperature of the paper-passing area W1. In the non-paper-passing area W2, since the temperature of the heat-conducting member 56B is lower than the temperature of the planar heating element 48, the heat Q is transferred from the planar heating element 48 to the heat-conducting member 56B.

[0100] The heat Q transferred to the heat conducting member 56B is conducted to the paper passing area W1 by the characteristics of the heat conducting member 56B (characteristics of conducting more heat in the Z direction than in the Y direction). And, in the paper passing area W1, the heat Q is transferred from the heat conducting member 56B to the planar heating element 48. As a result, the excess heat Q of the non-paper passing area W2 of the planar heating element 48 is transferred to the paper passing area W1 of the planar heating element 48, so that the temperature of the non-paper passing area W2 is reduced, and the temperature of the paper passing area W1 is increased. That is, the temperature difference in the Z direction of the planar heating element 48 is reduced.

[0101] Furthermore, if Figure 4A As shown in FIG. 1 , the end S1 of the heat-conducting member 56A and the end S2 of the heat-conducting member 56B are arranged so as to overlap when viewed from the X direction, so that the heat-conducting member 56 is always present (contacting) in a portion of the planar heating element 48 in the X direction. Therefore, since there is no region where the heat-conducting member 56 does not exist in the X direction, the non-paper-passing region W2 (refer to FIG. 1 ) of the planar heating element 48 with respect to the paper PA is made smaller than in the above-mentioned comparative example. Figure 7 ) is easily conducted and transferred in the Z direction. Thus, the temperature difference in the Z direction of the planar heating element 48 is suppressed.

[0102] Furthermore, since the temperature difference in the Z direction of the planar heating element 48 is suppressed, after the toner image G is fixed to the paper PA, the paper PB passes through the nip portion NP (see Figure 2 ), the occurrence of a temperature difference in the Z direction of the paper PB is suppressed. In addition, the occurrence of a temperature difference in the Z direction of the planar heating element 48 is suppressed, thereby suppressing the occurrence of a pressure difference in the Z direction inside the planar heating element 48 or inside the heat conducting component 56 caused by thermal expansion.

[0103] In the fixing device 30, the lengths of the adjacent heat-conducting members 56A and 56B in the X direction are set to be the same, and the entirety overlaps when viewed from the Z direction. As a result, the area of ​​the portion of the planar heating element 48 that is not in contact with the heat-conducting member 56 is reduced compared to a structure in which only a portion of each of the heat-conducting members 56A and 56B is opposed in the Z direction. In other words, in the planar heating element 48, since the area of ​​the portion where the heat-conducting member 56 conducts heat is increased, the temperature difference of the paper P in the Z direction is suppressed compared to a structure in which only a portion of each of the heat-conducting members 56A and 56B is opposed in the Z direction.

[0104] Furthermore, in the fixing device 30 , the facing surfaces 58A and 58B extend in the direction C. Therefore, compared with a structure in which the facing surfaces 58A and 58B are formed in a step shape, it is easier to cut out the facing surfaces 58A and 58B, and thus it is easier to manufacture the heat conductive member 56 .

[0105] According to the image forming apparatus 10 (refer to Figure 1 ), by including the fixing device 30, the temperature difference in the Z direction of the planar heating element 48 is suppressed compared with the structure in which the gap 57 is along the X direction. As a result, in the next fixing, when the paper PB wider than the paper PA passes through the nip portion NP (refer to Figure 2 ), the temperature difference in the Z direction of the paper PB is suppressed, so that image defects caused by the temperature difference in the Z direction of the planar heating element 48 are suppressed. As an example of image defects, there are image (toner image G) missing or image contamination when thermal offset occurs.

[0106] Fig. 8A The graph G1 shows the relationship between the heat conducting member 56A, the gap 57 and the heat conducting member 56B (see Figure 4A ) corresponding to the position in the Z direction, the uneven glossiness of the image at each position, and the threshold value K. In the fixing device 30 (refer to Figure 2 ) in the image, the glossiness of the image is uneven at position Z1 and position Z2 (refer to Figure 3A ) is lower than the threshold value K. This is considered to be because, at position Z2, heat conduction in the Z direction is performed and the temperature drop is suppressed compared with the above-mentioned comparative example.

[0107] Figure 8B The display position Z1 (refer to Figure 3A ) in the X direction and the temperature of the planar heating element 48. At position Z1, the heat conducting members 56A and 56B ( Figure 3A Therefore, even if the position in the X direction changes, the temperature of the planar heating element 48 is unlikely to differ.

[0108] Figure 8C The display shows the position Z2 (refer to Figure 3A ) and the temperature of the planar heating element 48. At position Z2, although it is lower than at position Z1, a part of the heat conducting members 56A and 56B is present, so heat is supplied to the planar heating element 48 in the Z direction, and the temperature of the planar heating element 48 is suppressed from being lower than the temperature at position Z1. Figure 5 ) the temperature locally rises and a peak can be seen.

[0109] <Modification>

[0110] Figure 3BTwo heat conducting members 72 (heat conducting members 72A and 72B) are shown as examples of the five heat conducting members 56 (see Figure 2 ). The heat-conducting components 72A and 72B are adjacently arranged near the front side and the back side relative to the center of the planar heating element 48 in the Z direction. When viewed from the Y direction, the heat-conducting component 72A is formed into a trapezoidal shape with the upper side in the X direction as the lower bottom side and the lower side in the X direction as the upper bottom side. When viewed from the Y direction, the heat-conducting component 72B is formed into a trapezoidal shape with the lower side in the X direction as the lower bottom side and the upper side in the X direction as the upper bottom side.

[0111] When viewed from the X direction, a portion of the heat-conducting member 72A overlaps a portion of the heat-conducting member 72B. In addition, when viewed from the Y direction, the gap 74 between the heat-conducting member 72A and the heat-conducting member 72B extends in an oblique direction intersecting the X direction. Furthermore, the Z-direction front end of the heat-conducting member 72A contacts the entire X-direction of the planar heating element 48. Thus, at both ends of the Z-direction of the planar heating element 48, the width of the heat-conducting member in the X direction can be expanded compared to the heat-conducting member 56 of the first embodiment.

[0112] [Second embodiment]

[0113] Next, the image forming apparatus 10 and the fixing device 80 according to the second embodiment are described. Components and locations that are basically the same as those of the image forming apparatus 10 and the fixing device 30 according to the first embodiment are denoted by the same reference numerals as those of the first embodiment, and their description is omitted.

[0114] Fig. 9 The fixing device 80 shown in the figure is different in that the fixing device 30 (see Figure 2 ) in the heat conducting member 56 (refer to Figure 2 ) is replaced by the heat conducting component 82, and the other structures are the same as those of the fixing device 30.

[0115] As an example, the heat-conducting component 82 and the heat-conducting component 56 are made of the same material (material), but only have different shapes. In addition, the heat-conducting component 82 is in contact with the back surface 55, and conducts more heat from the planar heating element 48 in the Z direction than in the Y direction. In addition, as an example, the heat-conducting component 82 is composed of two (one in the figure) heat-conducting components 84 arranged at both ends in the Z direction and three (two in the figure) heat-conducting components 86 arranged between the two heat-conducting components 84 in the Z direction. In other words, the heat-conducting component 84 and the heat-conducting component 86 are arranged with a gap (gap 87) in the Z direction and the X direction. Here, one heat-conducting component 84 and one heat-conducting component 86 adjacent to each other in the Z direction are described.

[0116] The heat conducting component 84 is an example of a heat conducting component, and is formed into a flat plate with the Y direction being the thickness direction. In addition, when viewed from the Y direction, the heat conducting component 84 has a main body 84A and an extension 84B extending in the Z direction from the end of the main body 84A in the Z direction. And the heat conducting component 84 overlaps (contacts) with the back surface 55 of the planar heating element 48. The main body 84A is formed into a rectangular shape that is longer in the Z direction. As an example, the length of the main body 84A in the X direction is set to be substantially the same as the length of the planar heating element 48 in the X direction.

[0117] The extension portion 84B protrudes from one end of the main body 84A in the Z direction and the portion constituting the lower side in the X direction toward the center of the planar heating element 48 in the Z direction. In addition, the extension portion 84B is formed into a rectangular shape that is longer in the Z direction. Furthermore, as an example, the length of the extension portion 84B in the X direction is set to about 2 / 5 of the length of the main body 84A in the X direction. As an example, the length of the extension portion 84B in the Z direction is set to about 1 / 4 of the length of the main body 84A in the Z direction.

[0118] The heat-conducting component 86 is an example of other heat-conducting components, and is formed into a flat plate with the Y direction as the thickness direction. In addition, when observed from the Y direction, the heat-conducting component 86 has a main body 86A, an extension 86B extending in the Z direction from the near front end of the main body 86A in the Z direction, and an extension 86C extending in the Z direction from the inner end of the main body 86A in the Z direction. In addition, the heat-conducting component 86 overlaps (contacts) with the back surface 55. The main body 86A is formed into a rectangular shape that is longer in the Z direction. As an example, the length of the main body 86A in the X direction is set to be substantially the same as the length of the planar heating element 48 in the X direction (the length of the main body 84A in the X direction).

[0119] The extension portion 86B protrudes from the portion of the main body 86A which is near the front side in the Z direction and constitutes the upper side in the X direction toward the near front side in the Z direction. In addition, the extension portion 86B is formed into a rectangular shape which is long in the Z direction. Furthermore, as an example, the length of the extension portion 86B in the X direction is set to about 2 / 5 of the length of the main body 86A in the X direction. As an example, the length of the extension portion 86B in the Z direction is set to about 1 / 4 of the length of the main body 86A in the Z direction.

[0120] The extension portion 86C protrudes from the Z-direction inner end of the main body 86A and the lower side of the X-direction toward the center side of the planar heating element 48 in the Z-direction. In addition, the extension portion 86C is formed into a rectangular shape that is longer in the Z-direction. Furthermore, as an example, the length of the extension portion 86C in the X-direction is set to about 2 / 5 of the length of the main body 86A in the X-direction. As an example, the length of the extension portion 86C in the Z-direction is set to about 1 / 4 of the length of the main body 86A in the Z-direction.

[0121] When viewed from the X direction, the extension portion 84B and the extension portion 86B are arranged so as to overlap in the X direction. As an example, the overlapping portion is located outside the end of the paper PA in the Z direction and inside the end of the paper PB in the Z direction. In addition, the heat conducting member 84 and the heat conducting member 86 are opposed to each other in the Z direction over the entire X direction.

[0122] When viewed from the Y direction, the gap 87 is formed in a crank shape in which a portion along the X direction and a portion along the Z direction are alternately connected. The surface of the heat conducting member 84 that forms the side surface of the gap 87 and is arranged in the X direction is referred to as an opposing surface 88A. In addition, the surface of the heat conducting member 86 that forms the side surface of the gap 87 and is arranged in the X direction is referred to as an opposing surface 88B. That is, when viewed from the Y direction, the opposing surface 88A and the opposing surface 88B extend in the Z direction, respectively, and are opposed in the X direction. The opposing surface 88A and the opposing surface 88B are examples of opposing edges that are opposed to each other.

[0123] The portion of the extension portion 84B that overlaps with the extension portion 86B in the X direction forms a quadrilateral. Points A, B, C, and D represent the vertices of the quadrilateral. The portion of the extension portion 86B that overlaps with the extension portion 84B in the X direction forms a quadrilateral. Points E, F, G, and H represent the vertices of the quadrilateral. Points B, A, H, and G are arranged on an imaginary line V3 along the X direction. Points C, D, E, and F are arranged on an imaginary line V4 along the X direction.

[0124] Here, regarding the heat conducting member 84 and the heat conducting member 86, the portion between the imaginary line V3 and the imaginary line V4 in the Z direction (referred to as region N2) is an overlapping portion when viewed from the X direction. When viewed from the Y direction, this portion is composed of the end S3 represented by the quadrilateral ABCD and the end S4 represented by the quadrilateral EFGH. The end S3 is a part of the heat conducting member 84. The end S4 is a part of the heat conducting member 86.

[0125] At the end S3, heat is conducted with other parts of the heat conducting member 84. At the end S4, heat is conducted with other parts of the heat conducting member 86. The region N2 is located between the Z-direction front end of the paper PA and the Z-direction front end of the paper PB.

[0126] A plurality of corners 92A, 92B, 92C, and 92D are formed at the positions where the adjacent heat conducting members 84 and 86 face each other. The corners 92A and 92B form the corners of the extension portion 84B. The corners 92C and 92D form the corners of the extension portion 86B. And, when viewed from the Y direction, as an example, the angles of the corners 92A, 92B, 92C, and 92D are all set to 90 degrees. In addition, the angle of 90 degrees is not limited to exactly 90 degrees, and also includes angles that have different values ​​relative to 90 degrees within the range of angle measurement error.

[0127] 〔effect〕

[0128] Next, the operation of the second embodiment will be described. In addition, the description of the same structure and operation as those of the first embodiment will be omitted.

[0129] According to the fixing device 80, the extending portion 84B and the extending portion 86B are arranged side by side in the X direction, and thus the gap 87 is aligned with the C direction intersecting the X direction (see Figure 4A ) compared to the structure extending upward, the gap 87 in the X direction becomes smaller.

[0130] Furthermore, according to the fixing device 80, by having the corners 92A, 92B, 92C, and 92D, the rigidity of the heat conducting members 84 and 86 against the force acting in the Y direction is increased compared to a structure in which at least one corner is an acute angle, and deformation of the heat conducting members 84 and 86 in the Y direction is suppressed.

[0131] Fig.10 The graph G4 shows that the fixing device 80 (refer to Fig. 9 ), when the gap 87 (refer to Fig. 9 ) in the X direction [mm], the planar heating element 48 ( Fig. 9 Reference) in the X direction. In addition, as an example, the planar heating element 48 uses a component made of aluminum oxide and having a thickness of 1 [mm]. As an example, the heat conduction components 84 and 86 use a component made of graphite sheets and having a thickness of 50 [μm]. The paper P to be fixed is A4 plain paper, and the conveying speed is set to 35 [sheets / min].

[0132] In the graph G4, when the length (interval) of the gap 87 in the X direction is longer, the temperature difference becomes larger. Here, it is confirmed that the change rate of the temperature difference in the interval of 5 [mm] to 10 [mm] is smaller than the change rate of the temperature difference in the interval of 0 [mm] to 5 [mm]. It is considered that this is because the longer the length of the gap 87 in the X direction, the greater the contribution of the heat conduction in the Z direction of the heat conduction members 84 and 86.

[0133] [Third Embodiment]

[0134] Next, the image forming apparatus 10 and the fixing device 100 according to the third embodiment are described. Components and locations that are basically the same as those of the image forming apparatus 10 and the fixing device 30 according to the first embodiment are given the same reference numerals as those of the first embodiment and their description is omitted.

[0135] Fig.11 The fixing device 100 shown in the figure is different in that the fixing device 30 (refer to Figure 2 ) in the heat conducting member 56 (refer to Figure 2 ) is replaced by the heat conducting component 102, and the arrangement of the resistor 52 is changed, and the other structures are the same as those of the fixing device 30.

[0136] The heat conducting member 102 is a member that contacts the back surface 55 and conducts the heat of the planar heating element 48 in the Z direction, and is made of graphite, for example. The heat conductivity in the Z direction of the heat conducting member 102 is higher than the heat conductivity in the Z direction of the substrate 49. That is, in the heat conducting member 102, more heat is conducted in the Z direction than in the Y direction.

[0137] In addition, as an example, the heat-conducting member 102 is composed of two heat-conducting members 104 arranged at a distance in the Z direction, and one heat-conducting member 106 located between the two heat-conducting members 104 and located in the center in the Z direction. The heat-conducting members 104 and the heat-conducting members 106 are arranged at a distance (gap 107) in the Z direction and the X direction. The two heat-conducting members 104 are arranged in a substantially line-symmetrical manner in the Z direction with respect to an imaginary line V5 passing through the center of the heat-conducting member 106 and along the X direction. Therefore, the heat-conducting member 104 and the heat-conducting member 106 on the front side in the Z direction will be described, and the description of the heat-conducting member 104 on the back side in the Z direction will be omitted.

[0138] The heat-conducting component 104 is an example of a heat-conducting component, and is formed into a flat plate with the Y direction as the thickness direction. In addition, the outer shape of the heat-conducting component 104 when viewed from the Y direction is a trapezoid. Specifically, the upper base and the lower base of the trapezoid of the heat-conducting component 104 are along the Z direction. The waist of the trapezoid of the heat-conducting component 104 near the front side in the Z direction is along the X direction, and the waist on the inner side constitutes an oblique side intersecting the X direction. The heat-conducting component 104 overlaps with the back surface 55. As an example, the length of the heat-conducting component 104 in the X direction is equal to the length of the planar heating element 48 in the X direction.

[0139] The heat-conducting component 106 is an example of other heat-conducting components, and is formed into a flat plate with the Y direction as the thickness direction. In addition, as an example, the outer shape of the heat-conducting component 106 when viewed from the Y direction is an isosceles trapezoid. Specifically, the upper surface 106B of the heat-conducting component 106, which is equivalent to the lower base of the trapezoid, is arranged on the upper side in the X direction, and is a surface along the Y-Z direction. The lower surface 106C of the heat-conducting component 106, which is equivalent to the upper base of the trapezoid, is arranged on the lower side in the X direction, and is a surface along the Y-Z direction. The two legs of the heat-conducting component 106 are respectively oblique sides intersecting the X direction. The heat-conducting component 106 overlaps with the back surface 55. As an example, the length of the heat-conducting component 106 in the X direction is slightly shorter than the length of the planar heating element 48 in the X direction.

[0140] The heat conducting member 104 and the heat conducting member 106 are adjacent to each other in the Z direction. When viewed from the X direction, the Z direction rear end of the heat conducting member 104 and the Z direction front end of the heat conducting member 106 are arranged so as to overlap in the X direction. As an example, the overlapping portion (ends S5 and S6 described later) is located between the two ends of the paper PA in the Z direction. In addition, the heat conducting member 104 and the heat conducting member 106 are opposed to each other in the Z direction over the entire X direction.

[0141] When viewed from the Y direction, the gap 107 extends linearly in an inclined direction intersecting the X direction. Here, the side surface of the heat conducting member 104 forming the gap 107 is referred to as an opposing surface 104A. In addition, the side surface of the heat conducting member 106 forming the gap 107 is referred to as an opposing surface 106A. That is, when viewed from the Y direction, the opposing surface 104A and the opposing surface 106A extend in an inclined direction, respectively, and face each other with the gap 107 in a direction perpendicular to the inclined direction. The opposing surface 104A and the opposing surface 106A are examples of opposing edges facing each other.

[0142] When viewed from the Y direction, the position of the opposing surface 104A that constitutes the inner end in the Z direction (the vertex of the acute angle of the parallelogram) is represented by point A. Point A is located on the lower surface 104C of the heat conducting member 104 located on the lower side in the X direction. In addition, the line passing through point A and along the X direction is called an imaginary line V6. The surface of the heat conducting member 104 located at the upper end in the X direction is called the upper surface 104B. The surface of the heat conducting member 106 located at the upper side in the X direction is called the upper surface 106B, and the surface of the heat conducting member 106 located at the lower end in the X direction is called the lower surface 106C.

[0143] Point D indicates the position of the Z-direction front end (the vertex of the acute angle of the parallelogram) of the facing surface 106A. In addition, point E indicates the intersection of the imaginary line V6 and the facing surface 106A, and point F indicates the intersection of the imaginary line V6 and the upper surface 106B. The line passing through point D and along the X direction is called imaginary line V7. Point B indicates the intersection of the imaginary line V7 and the facing surface 104A, and point C indicates the intersection of the imaginary line V7 and the lower surface 104C.

[0144] Regarding the heat conducting member 104 and the heat conducting member 106, the portion located between the imaginary line V6 and the imaginary line V7 in the Z direction (referred to as region N3) is an overlapping portion when viewed from the X direction. When viewed from the Y direction, this portion is composed of the end S5 indicated by the triangle ABC and the end S6 indicated by the triangle DEF. In the end S5, heat conduction is performed with other portions of the heat conducting member 104. In the end S6, heat conduction is performed with other portions of the heat conducting member 106.

[0145] In the heat conductive member 106, as an example, one corner when viewed from the Y direction, and an obtuse angle portion obtained by removing the end S6 is referred to as an obtuse angle portion 108. The obtuse angle portion 108 is a portion where the lower surface 106C and the facing surface 106A intersect.

[0146] When projected in the Y direction, the heating portion 52A overlaps with the obtuse angle portion 108 (the portion on the obtuse angle side). When projected in the Y direction, the heating portion 52B overlaps with the end portion S5 and the end portion S6. In other words, as an example, the resistor 52 is arranged at a position lower than the center of the planar heating element 48 in the X direction (upstream in the conveying direction of the paper PA).

[0147] 〔effect〕

[0148] Next, the operation of the third embodiment will be described. In addition, the description of the same structure and operation as those of the first embodiment will be omitted.

[0149] According to the fixing device 100, since the outer shape of the heat conducting member 106 when viewed from the Y direction is a trapezoid, unlike the case where the outer shape is a parallelogram, the shape of the back side portion and the shape of the front side portion of the heat conducting member 106 in the Z direction are line-symmetrical about the imaginary line V5. Thus, the heat conducting member 102 composed of the heat conducting member 104 and the heat conducting member 106 can be symmetrically arranged about the center of the planar heating element 48 in the Z direction.

[0150] Furthermore, according to the fixing device 100, when projected in the Y direction, the heat generating portion 52A overlaps with the obtuse angle portion 108. Therefore, compared with a structure in which the heat generating portion 52A overlaps with the acute angle portion of the heat conducting member 106, the volume of the heated portion of the heat conducting member 106 is large, so that a part of the heat conducting member 106 is suppressed from being heated intensively. That is, compared with a structure in which the resistor 52 overlaps with the acute angle portion of the heat conducting member 106, deformation of the heat conducting member 106 due to heating is suppressed.

[0151] <Modification>

[0152] Fig.12 Heat conducting members 112 and 114 are shown as modified examples of the third embodiment.

[0153] The heat conducting member 112 is an example of a heat conducting member, and the end S5 ( Fig.11 The front end portion of the heat conducting member 104 (see FIG. 1 ) is cut in the X direction to form a trapezoidal end portion S7 with the Z direction as the height direction when viewed from the Y direction. Fig.11 )different.

[0154] The heat conducting member 114 is an example of another heat conducting member, and the end S6 (see Fig.11 ) is cut in the X direction to form a trapezoidal end S8 with the Z direction as the height direction when viewed from the Y direction, which is similar to the heat conducting member 106 (see Fig.11 ) is different. When viewed from the X direction, the end S7 overlaps with the end S8. In addition, regarding the heat conducting members 112 and 114, the same reference numerals are given to the same parts as the heat conducting members 104 and 106, and the description thereof is omitted.

[0155] The four vertices of the end S7 are represented by points A, B, C, and D. The line segment AB corresponds to the upper base of the trapezoid, and the line segment CD corresponds to the lower base of the trapezoid. The line segment AD is located on the opposing surface 104A. In addition, the endpoint on the side opposite to point A of the opposing surface 104A is set to point M. Similarly, the four vertices of the end S8 are represented by points E, F, G, and H. The line segment EF corresponds to the upper base of the trapezoid, and the line segment GH corresponds to the lower base of the trapezoid. The line segment EH is located on the opposing surface 106A. In addition, the endpoint on the side opposite to point E of the opposing surface 106A is set to point N.

[0156] When viewed from the Y direction, the angle of the corner 116A including the point B, the angle of the corner 116B including the point A, and the angle of the corner 116C including the point M are all obtuse angles of 90 degrees or more. Similarly, when viewed from the Y direction, the angle of the corner 118A including the point F, the angle of the corner 118B including the point E, and the angle of the corner 118C including the point M are all obtuse angles of 90 degrees or more. Thus, in the heat conductive members 112 and 114, all the corners of the portions facing each other in the Z direction can be set at obtuse angles. Thus, even if the heat conductive members 112 and 114 are heated by the resistor 52, deformation of the heat conductive members 112 and 114 is suppressed.

[0157] [Fourth embodiment]

[0158] Next, the image forming apparatus 10 and the fixing device 120 according to the fourth embodiment will be described. In addition, the same reference numerals as those in the first embodiment are given to the components and parts that are basically the same as those in the image forming apparatus 10 and the fixing device 30 according to the first embodiment, the fixing device 80 according to the second embodiment, and the fixing device 100 according to the third embodiment, and the description thereof will be omitted.

[0159] Fig.13 The fixing device 120 shown in FIG. 1 is different in that the fixing device 30 (see FIG. Figure 2 ) wherein a plurality of heat conducting members 56 (see Figure 2 ) are replaced by a plurality of heat conducting members 122, and the other structures are the same as those of the fixing device 30. Here, a group of heat conducting members 122 adjacent in the Z direction will be described. Two adjacent heat conducting members 122 are arranged with a gap (gap 127) in the Z direction and the X direction.

[0160] The heat conducting member 122 is a member that contacts the back surface 55 and conducts the heat of the planar heating element 48 in the Z direction, and is made of graphite, for example. Figure 5 ), the thermal conductivity of the heat conducting member 122 in the Z direction is higher than the thermal conductivity of the heat conducting member 122 in the Y direction. That is, in the heat conducting member 122, more heat is conducted in the Z direction than in the Y direction.

[0161] The heat conducting member 122 is formed in a flat plate shape with the Y direction as the thickness direction. Furthermore, when viewed from the Y direction, most of the outer shape of the heat conducting member 122 is formed in a rectangular shape that is long in the Z direction. An end face 123 that is partially along the X direction is formed at the Z-direction front end of the heat conducting member 122. A recessed portion 126 that is recessed in the Z direction when viewed from the Y direction is formed at the X-direction center of the end face 123. Another end face 124 that is partially along the X direction is formed at the Z-direction back end of the heat conducting member 122. A protrusion 128 that protrudes in the Z direction when viewed from the Y direction is formed at the X-direction center of the end face 124.

[0162] The recessed portion 126 is recessed from the end surface 123 toward the inner side in the Z direction. The shape of the recessed portion 126 is a quadrilateral along the X direction and the Z direction. In other words, the end portion of the heat conducting member 122 near the front side in the Z direction is formed into a U-shape that opens toward the front side in the Z direction. In addition, in the heat conducting member 122, the portion on the upper side in the X direction relative to the recessed portion 126 is called an extension portion 132, and the portion on the lower side in the X direction relative to the recessed portion 126 is called an extension portion 133.

[0163] Corners 132A and 132B are formed at the ends of the extension portion 132 in the Z direction. As an example, the angle between the corners 132A and 132B when viewed from the Y direction is 90 degrees. In addition, an end S9 represented by a quadrilateral ABCD is set in the extension portion 132 .

[0164] Corner portions 133A and 133B are formed at the ends of the extension portion 133 in the Z direction. As an example, the angle between the corner portions 133A and 133B when viewed from the Y direction is 90 degrees. In addition, an end portion S10 indicated by a quadrilateral EFGH is set in the extension portion 133 .

[0165] The protrusion 128 protrudes from the end surface 124 toward the inner side in the Z direction. The shape of the protrusion 128 is a quadrilateral along the X direction and the Z direction. And, the protrusion 128 is inserted into the recessed portion 126. The length of the protrusion 128 in the X direction is shorter than the length of the recessed portion 126 in the X direction. In addition, as an example, the length of the protrusion 128 in the Z direction is set to a length that is equal to the length of the extension portion 132 or the extension portion 133 in the Z direction. Furthermore, corners 128A and 128B are formed at the ends of the protrusion 128. As an example, the angle when the corners 128A and 128B are observed from the Y direction is 90 degrees. In addition, an end S11 represented by a quadrilateral IJKL is set in the protrusion 128.

[0166] A line passing through points A, B, L, K, F, and E and along the X direction is referred to as an imaginary line V8. A line passing through points D, C, I, J, G, and H and along the X direction is referred to as an imaginary line V9. With respect to the adjacent heat conducting members 122, the portion located between the imaginary line V8 and the imaginary line V9 in the Z direction (referred to as region N4) is the portion that overlaps when viewed from the X direction. In other words, the end portions S9, S10, and S11 are located within the region N4.

[0167] When viewed from the Y direction, the gap 127 is formed into a crank shape that is bent at approximately right angles at four locations. As an example, the length of the gap 127 in the Z direction and the length in the X direction are set to the same degree of length. Here, the surface of the extension portion 132 that is opposite to the protrusion 128 in the X direction is called the opposing surface 132C. The surface of the protrusion 128 that is opposite to the extension portion 132 in the X direction is called the opposing surface 128C. The surface of the protrusion 128 that is opposite to the extension portion 133 in the X direction is called the opposing surface 128D. The surface of the extension portion 133 that is opposite to the protrusion 128 in the X direction is called the opposing surface 133C. The opposing surfaces 132C, 128C, 128D, and 133C are examples of opposing edges that are opposite to each other, and are all set as surfaces along the Z direction when viewed from the Y direction.

[0168] 〔effect〕

[0169] Next, the operation of the fourth embodiment will be described. In addition, the description of the same structure and operation as those of the first and second embodiments will be omitted.

[0170] In the operation (during manufacturing) of bonding a plurality of heat-conducting components 122 to the planar heating element 48, the protrusion 128 is inserted into the recess 126, so that the end S9 is arranged on the upper side (one side) in the X direction relative to the end S11, and the end S10 is arranged on the lower side (the other side) in the X direction. Here, when one heat-conducting component 122 is offset in the X direction, the protrusion 128 contacts the extension 132, or the protrusion 128 contacts the extension 133. Thus, compared with a structure in which the protrusion 128 is not inserted into the recess 126, the situation in which the heat-conducting component 122 is greatly offset in the X direction during the manufacturing of the fixing device 120 is suppressed.

[0171] In addition, the present disclosure is not limited to the above-mentioned embodiments.

[0172] In the fixing device 30 , the lengths of the plurality of heat conducting members 56 in the X direction may not be the same. Furthermore, the plurality of heat conducting members 56 may at least partially overlap when viewed from the Z direction. Parts of the facing surfaces 58A and 58B may be along the X direction.

[0173] In the fixing device 80 , the facing surfaces 88A and 88B may face each other in a direction intersecting the direction X. The heat conducting member 82 may have an acute angle portion.

[0174] In the fixing device 100, the lengths of the heat conducting members 104 and 106 in the X direction may not be the same. In addition, when viewed from the Z direction, at least a portion of the heat conducting members 104 and 106 may overlap. Furthermore, the number of heat conducting members included in the heat conducting member 102 is not limited to three, and may be an odd number of three or more. Parts of the facing surfaces 104A and 106A may be along the X direction. The resistor 52 may not be disposed at the obtuse angle portion 108.

[0175] In the fixing device 120 , the facing surfaces 128C, 128D, 132C, and 133C may face each other in a direction intersecting the direction X. The heat conducting member 122 may have an acute angle portion.

[0176] The rotating body is not limited to the belt 46, and may be a cylindrical member made of resin.

[0177] The heat conducting components 56, 82, 102, 122 are not limited to flat plate-shaped components along the X-Z plane, and may be, for example, components that are bent so as to protrude upward or downward in the X direction when viewed from the Z direction. In the case where a plurality of heat conducting components are bent components, they may be arranged so as to overlap in the X direction when viewed from the X direction in a state where the X-Z plane (plane) is unfolded. In addition, the heat conducting components 56, 82, 102, 122 may be made of different materials so that the heat conductivity of the components on the end sides is higher than that of the components on the center side in the Z direction.

[0178] The thickness of the heat conductive member 56 , 82 , 102 , 122 may be different in the X direction. For example, the thickness may be changed in the X direction by overlapping and affixing a sheet-like heat conductive member and a part of the heat conductive member 56 , 82 , 102 , 122 in the Y direction.

[0179] As long as a portion of each of the plurality of heat-conducting components is arranged so as to overlap in the X direction, it is also possible to arrange them at intervals in the X direction. Although not shown in the figure, for example, there are rectangular heat-conducting components A and B adjacent to each other in the Z direction, and rectangular heat-conducting components C and D adjacent to each other in the Z direction. Furthermore, there is a gap d1 along the X direction between the heat-conducting components A and B, and there is a gap d2 along the X direction between the heat-conducting components C and D. Here, as long as the heat-conducting components A, B, C, and D are arranged so that the gap d1 and the gap d2 are not arranged in the X direction, heat conduction can be performed at any position in the Z direction through any position in the X direction.

[0180] In the fixing devices 30, 80, 100, and 120, each planar heating element and each heat-conducting member may not be arranged at a position corresponding to the clamping portion NP. For example, a fixing device may be provided with a planar heating element and a heat-conducting member at a position upstream of the clamping portion NP in the rotation direction of the belt 46 and inside the belt 46. In this fixing device, the belt 46 is heated at a position upstream of the clamping portion NP, and the toner image G of the belt 46 is heated and pressurized in the clamping portion NP.

[0181] In the image forming apparatus 10 , an inkjet (liquid droplet ejection) image forming unit may be used instead of the image forming unit 16 , and the obtained developer image may be fixed by the fixing device 30 , 80 , 100 , 120 .

[0182] The present disclosure is not limited to the above-described embodiments, and various modifications and applications are possible without departing from the gist of the present disclosure.

Claims

1. A fixing device, in, The fixing device comprises: A hollow rotating body; a planar heating element disposed inside the rotating body and extending in a width direction perpendicular to a conveyance direction of a recording medium conveyed along with the rotation of the rotating body, for heating the rotating body; and a plurality of heat-conducting members which are in contact with a surface of the planar heat generating element on the opposite side of the contact surface of the rotating element and are arranged at intervals in the width direction and the conveying direction so that heat of the planar heat generating element is conducted in the width direction, and when viewed from the conveying direction in a flat unfolded state, the plurality of heat-conducting members are arranged so that a portion of one of the heat-conducting members overlaps a portion of another heat-conducting member adjacent to the one heat-conducting member, When viewed from a thickness direction perpendicular to the conveying direction and the width direction, at least a portion of mutually opposing edges of adjacent heat conducting members are opposed in the conveying direction. A recessed portion that is recessed in the width direction when viewed from the thickness direction is formed on an end surface in the width direction of one of the adjacent heat conducting members, A protrusion that protrudes in the width direction when viewed from the thickness direction is formed on the end surface of the other of the adjacent heat conducting members in the width direction, The protrusion is inserted into the recess.

2. The fixing device according to claim 1, in, A plurality of corners are formed at mutually opposing locations of adjacent heat conducting members, When viewed from a thickness direction perpendicular to the conveying direction and the width direction, all of the angles of the plurality of corners are equal to or greater than 90 degrees.

3. An image forming device, in, The image forming device comprises: an image forming unit that forms a developer image on a recording medium; as well as The fixing device according to claim 1 or 2, wherein the developer image is fixed to the recording medium by heating and applying pressure to the developer image.

Images