Fixation device and image formation device

Abstract

To solve the problem in a fixation device equipped with a mechanism absorbing expansion accompanied by heating of a heating member in which distortion of the heating member cannot be suppressed and thus a malfunction may occur in a heater accompanied by repeated state displacements.SOLUTION: A fixation device comprises: a fixation belt 110 that extends in an arrow Y direction; a pressure roller 102 that is arranged in a way capable of forming a nip part while facing the fixation belt 110; a heater 121 that extends in the same direction, and heats the fixation belt 110; a stay 111 that extends in the same direction, and supports the heater 121; right and left support levers 112 and 113 and compression spring that are for urging the stay 111 to urge the heater 121 against the pressure roller 102; front and rear connectors 141 and 142 that are electrically connected to the heater 121; and a connector holder 130 that holds the connectors 141 and 142 to maintain the electrical connection to the heater 121, and is supported freely oscillatably relative to the stay 111.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus, and more particularly to a fixing device having a holding mechanism for a heat generating member. [Background technology]

[0002] 2. Description of the Related Art Conventionally, there has been a fixing device provided with a mechanism for absorbing the expansion of a heating member caused by heating of the heating member (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-71639 A (Page 12, FIG. 5) Summary of the Invention [Problem to be solved by the invention]

[0004] However, since the distortion of the heating member caused by the state change operation cannot be suppressed, particularly when a thin heater is used as the heating member, repeated state change operations can cause malfunction of the heater. [Means for solving the problem]

[0005] The fixing device according to the present invention comprises: The device is characterized by comprising a first rotating body extending in a first direction, a second rotating body extending in the first direction and positioned so as to form a nip portion while facing the first rotating body, a heating portion extending in the first direction and heating the first rotating body, a support body extending in the first direction and supporting the heating portion, a biasing mechanism biasing the support body to bias the heating portion against the second rotating body, a connection portion electrically connected to the heating portion, and a holding portion supporting the connection portion to maintain electrical connection with the heating portion and supported so as to be freely swingable relative to the support body. Effect of the Invention

[0006] According to the fixing device of the present invention, since the distortion caused by the state change operation of the heating member can be suppressed, it is possible to suppress malfunction of the heating member caused by repeated state change operations. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram showing a configuration of a main part of an image forming apparatus according to a first embodiment of the present invention, which is provided with a fixing device; [Diagram 2] 2 is a perspective view of the appearance of a fixing belt unit and a pressure roller which constitute the main part of the fixing device according to the present invention; FIG. [Diagram 3] 1A is a front view of the fixing belt unit and the pressure roller as viewed in the direction of arrow A (X direction), which is the conveying direction of the recording paper, and FIG. [Figure 4] 3(b), (b) is a partially enlarged view of the left end portion thereof, and (c) is a further partially enlarged view of the vicinity of the spacer. [Diagram 5] 3(a) is a cross-sectional view taken along line BB in FIG. 3(a), and FIG. [Figure 6] 1A is a diagram illustrating a connector holder, in which (a) is an external perspective view of the connector holder alone, (b) is a left side view of the connector holder, and (c) is a DD cross-sectional view of (b). FIG. [Figure 7] FIG. 3(b) is a cross-sectional view taken along line CC of FIG. [Figure 8] 3(a) are cross-sectional views for explaining the operation of the present invention, taken near the left end of cross-section EE, slightly before cross-section AA in FIG. 3(a). (a) is a cross-sectional view showing a case where the lower surface of the lower wall of the connector holder is higher than the lower surface of the heater holder facing the pressure roller, and (b) is a cross-sectional view showing a case where the lower surface of the heater holder facing the pressure roller is higher than the lower surface of the lower wall of the connector holder. [Figure 9]FIG. 1A is a diagram for explaining the stay employed in the fixing device of the present invention and the comparative example device, and FIG. 1B is a schematic diagram emphasizing the bulge in the center of the stay to explain the crown shape. [Figure 10] FIG. 8(a) is an image diagram emphasizing the state of each part when the connector holder holding the left end of the heater is tilted clockwise. [Figure 11] FIG. 1 is a conceptual diagram illustrating a schematic configuration of a first modified example of the first embodiment. [Figure 12] 1A and 1B are schematic diagrams showing the configuration of variant example 2 of embodiment 1, in which (a) shows an example in which the center of oscillation is shifted from the center of the connector in the width direction, (b) shows an example in which the center of oscillation is a convex portion, and (c) shows an example in which a support portion for oscillation is formed on the stay side. [Figure 13] FIG. 11 is a cross-sectional view of a connector holder and its surroundings that constitute the comparative example device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Embodiment 1 FIG. 1 is a schematic diagram illustrating a main configuration of an image forming apparatus 1000 according to a first embodiment of the present invention, which is equipped with a fixing device 100 according to the present invention.

[0009] The image forming apparatus 1000 shown in the figure has a configuration as, for example, a color electrophotographic printer, and inside the apparatus is installed a paper feed cassette 1004 that stores recording paper 1001 as a recording medium, a paper feed roller 1005 that removes the recording paper 1001 from the paper feed cassette 1004, and a registration roller 1006 that feeds the recording paper 1001 to the image forming section at a predetermined timing.

[0010] Also, within the image forming apparatus 1000, as image forming sections, there are a developing device 1010K which forms a toner image as a black (K) developer image, a developing device 1010Y which forms a yellow (Y) toner image, a developing device 1010M which forms a magenta (M) toner image, and a developing device 1010C which forms a cyan (C) toner image (these developing devices may be simply referred to as 1010 when there is no need to distinguish between them), which are arranged in this order from the upstream side along the transport path of the recording paper 1001. These developing devices 1010 have the same configuration except that they use toner of a predetermined color.

[0011] As shown, for example, in developing device 1010K that uses black (K) toner, each developing device 1010 includes a photosensitive drum 1011 as an electrostatic latent image carrier, and arranged around it in order from the upstream side in the rotation direction (arrow direction), a charging device 1012 that supplies charge to the surface of the photosensitive drum 1011 to charge it, an exposure device 1013 that selectively irradiates the charged surface of the photosensitive drum 1011 with light based on image data to form an electrostatic latent image, a developer supply device 1014 that develops the electrostatic latent image formed on the photosensitive drum 1011 with the toner to form a toner image, and a cleaning device 1015 that is arranged in contact with the photosensitive drum 1011 to remove toner remaining on the surface of the photosensitive drum 1011.

[0012] Also, within the image forming apparatus 1000, there is provided a belt-type transfer device 1020, which includes an endless transfer belt 1021 that transports the recording paper 1001 and sequentially transfers the toner images formed by each developing device onto the recording paper 1001 being transported, a drive roller 1022 that is rotated by a drive unit not shown in the figure to drive the endless transfer belt 1021 in the direction of arrow A, and a tension roller 1023 that pairs with the drive roller 1022 and tensions the endless transfer belt 1021.

[0013] A fixing device 100 is provided on the discharge side of the recording paper 1001 by the endless transfer belt 1021. The fixing device 100 has a fixing belt unit 101 and a pressure roller 102, and fixes the toner transferred onto the recording paper 1001 by applying heat and pressure. Conveyor rollers 1030 and 1031 are provided on the discharge side of the fixing device 100, and the printed recording paper 1001 discharged from the fixing device 100 is discharged to a paper discharge stacker 1032. The fixing device 100 will be described in detail later.

[0014] In addition, the X, Y, and Z directions in FIG. 1 are the X direction (arrow A direction) in which the recording paper 1001 passes through the developing devices 1010K, 1010Y, 1010M, and 1010C, the Y direction is the direction of the rotation axis of each photoconductor drum 1011, and the Z direction is the direction perpendicular to both of these directions. Furthermore, when the X, Y, and Z directions are shown in other figures described later, these directions indicate common directions. That is, the XYZ directions in each figure indicate the arrangement direction when the depicted parts of each figure constitute the image forming apparatus 1000 shown in FIG. 1. Furthermore, here, the Z direction is arranged to be approximately vertical.

[0015] In the above configuration, the printing operation of the image forming apparatus 1000 will be outlined with reference to Fig. 1. Note that the dotted arrow in the figure indicates the conveying direction of the recording paper 1001 being conveyed.

[0016] When the image forming apparatus 1000 is turned on and an operator performs a well-known operation to start image formation, the recording paper 1001 stored in the paper feed cassette 1004 is removed from the paper feed cassette 1004 by the paper feed roller 1005, and after the recording paper 1001 is corrected for skew by the registration roller 1006, it is transported to the image forming section consisting of four developing devices 1010 and a transfer device 1020 at a predetermined timing.

[0017] At this time, as the photoconductor drum 1011 rotates in the direction of the arrow, the surface of the photoconductor drum 1011 of each developing device 1010 is charged by the charging device 1012 to which a voltage is applied by a power supply device (not shown). Next, when the charged surface of the photoconductor drum 1011 reaches the vicinity of the exposure device 1013, it is exposed by the exposure device 1013, and an electrostatic latent image corresponding to the image information is formed on the surface of the photoconductor drum 1011. This electrostatic latent image is developed by the developer supply device 1014, and a toner image corresponding to each color is formed on the surface of the photoconductor drum 1011.

[0018] The recording paper 1001 conveyed to the image forming section is attracted to the endless transfer belt 1021 and conveyed in the direction of arrow A, and in the process of being sequentially nipped between the photoconductor drums 1011 rotating in the direction of the arrow of each developing device 1010 and the endless transfer belt 1021, toner images of each color of black (K), yellow (Y), magenta (M), and cyan (C) formed at a predetermined timing are sequentially transferred and superimposed, forming a color image of each color toner on the recording paper 1001. After the photoconductor drum 1011 is cleaned by scraping off residual toner remaining on the photoconductor drum 1011 after transfer by a cleaning device 1015, it is prepared for the next charging.

[0019] Next, the recording paper 1001, on whose surface a color image has been formed using toners of each color, is transported to the fixing device 100. The toner image on the recording paper 1001 is melted by pressure and heat applied by the fixing device 100 and fixed onto the recording paper 1001. Thereafter, the recording paper 1001 is discharged to a paper discharge stacker 1032 by conveying rollers 1030 and 1031, and the printing operation is completed.

[0020] FIG. 2 is an external perspective view of the fixing belt unit 101 and the pressure roller 102 constituting the main part of the fixing device 100 according to the present invention. FIG. 3(a) is a front view of the fixing belt unit 101 and the pressure roller 102 as viewed from the direction of the arrow A (X direction) which is the conveying direction of the recording paper 1001, and FIG. 3(b) is a left side view thereof. FIG. 4(a) is an AA cross-sectional view of FIG. 3(b), FIG. 4(b) is a partial enlarged view of the left end portion thereof, and FIG. 4(c) is a further partial enlarged view of the vicinity of the spacer 118 thereof. FIG. 5(a) is a BB cross-sectional view of FIG. 3(a), and FIG. 5(b) is a partial enlarged view thereof. In addition, as viewed from the direction of the arrow A (X direction) shown in FIG. 2, there are cases where the top (positive direction of the Z axis), bottom, left, right, front, and rear are specified.

[0021] 4(a) and 5, the fixing belt 110 as the first rotating body of the fixing belt unit 101 is formed endlessly and extends in the direction of the arrow Y (width direction) as a first direction, and inside thereof, a stay 111 as a support body formed with a U-shaped cross section extends in the same direction beyond both ends of the fixing belt 110. The stay 111 fixedly holds a left support lever 112 by a fixing screw 116 at a position beyond the left end of the fixing belt 110, and holds a right support lever 113 by a fixing screw 117 at a position beyond the right end of the fixing belt 110.

[0022] The left support lever 112 holds a left guide member 114 having an inner guide portion 114a that guides the upper part of the left end portion of the fixing belt 110 from the inside, and a left regulating portion 114b that regulates the leftward movement of the fixing belt 110. Similarly, the right support lever 113 holds a right guide member 115 having an inner guide portion 115a that guides the upper part of the right end portion of the fixing belt 110 from the inside, and a right regulating portion 115b that regulates the rightward movement of the fixing belt 110.

[0023] The stay 111 holds a heater holder 120 which holds a thin plate-like heater 121 extending in the width direction. The heater 121 as a heating unit is disposed along an attachment portion extending in the width direction (Y direction) at the bottom of the heater holder 120 as an intermediate member, as shown in Fig. 5(b), for example, and its lower surface is covered by a heat diffusion plate 122 attached to the heater holder 120 at a lower portion thereof. Furthermore, only the upper surface of the stay 111 extends further left than the fixing screw 116, and this leftmost end portion holds a connector holder 130 as described below.

[0024] The fixing belt unit 101 having the above-mentioned components is rotatably held by a main body of the fixing device 100 (not shown). That is, as shown in Fig. 2, a shaft disposed in the main body of the fixing device 100 is fitted into a left rotation hole 112a formed in the left support lever 112 and a right rotation hole 113a formed in the right support lever 113, and the fixing belt unit 101 is rotatably held around a rotation shaft 200.

[0025] The fixing belt unit 101 is supported by compression springs (not shown) between the spring receiving portion 112b of the left support lever 112 and the spring receiving portion 113b of the right support lever 113 and the fixing device body, and each of these receives a predetermined force F1, thereby biasing the fixing belt unit 101 in the direction of arrow B around the rotation axis 200.

[0026] Furthermore, the fixing belt unit 101 is rotated to a position between a movable position where a predetermined amount of nip is generated between the fixing belt 110 and the pressure roller 102 by the biasing force generated by a compression spring, as shown in Fig. 5(b), and a retracted position where they are separated. The left support lever 112, the right support lever 113, and the compression spring, not shown, correspond to a biasing mechanism.

[0027] The pressure roller 102 as the second rotating body has a rotating shaft 102a rotatably held by the main body of the fixing device 100, and rotates in the direction of the arrow C as necessary by receiving a rotational force transmitted from outside the main body of the fixing device 100. Therefore, when the fixing belt unit 101 is in the movable position, the pressure roller 102 is driven to rotate in the direction of the arrow C, and the fixing belt 110 rotates with it, and the recording paper 1001 to which the toner has been transferred, which is sent to the nip portion, is heated and pressurized to fix the toner while sending it downstream. At this time, the heater 121 is in a heated state by an electric current supplied from the outside via a connector, which will be described later.

[0028] Next, a description will be given of the connector holder 130 as a holding part supported on the leftmost end of the stay 111. Fig. 6 is a diagram for explaining the connector holder 130, in which Fig. 6(a) is an external perspective view of the connector holder 130 alone, Fig. 6(b) is a left side view of the connector holder 130, and Fig. 6(c) is a DD cross-sectional view of Fig. 6(b).

[0029] 6, connector holder 130 is integrally formed with hollow outer casing 131 having a rectangular cross section, upper wall 132 dividing the hollow interior into three sections in the vertical direction, and lower wall 133. A square upper opening 134a is formed in top plate 134 of outer casing 131 into which a part of spacer 118 (described later) is fitted. A plurality of protrusions 133a extending in the front-rear direction are arranged at approximately equal intervals on the upper surface of lower wall 133.

[0030] Further, on the underside of the outer casing 131, a front step 131b and a rear step 131c are formed which are upside down with respect to the center in the fore-aft direction, and on the left and right side portions of the outer casing 131, as described below, through holes 131d, 131e are formed which extend in the fore-aft direction so as to be flush with the underside of the lower wall 133, through which a left end portion 121a (see FIG. 4(b)) of the heater 121 as a second exposed portion passes, and further, a left opening 131f and a right opening 131g are formed through which an upper extension portion 111a (see FIG. 4(b)) of the stay 111 as a first exposed portion passes.

[0031] The connector holder 130 having the above-mentioned shape is attached to the upper extension 111a of the stay 111 penetrating the left opening 131f and the right opening 131g by a locking screw 119 via a spacer 118 that fits into the upper opening 134a, as shown in Fig. 4(b) and Fig. 6. During this attachment, the left end 121a of the heater 121 extending further leftward from the left end of the heater holder 120 penetrates the left and right through-holes 131d, 131e of the connector holder 130 and protrudes to the left side of the connector holder 130. The left opening 131f and the right opening 131g are arranged to face each other with an internal space therebetween, forming an insertion portion 135 through which the upper extension 111a of the stay 111 penetrates.

[0032] As shown in FIG. 4(c), the spacer 118 has an insertion portion 118a that fits into an upper opening 134a of the top plate 134 of the connector holder 130 to regulate the front-back, left-right and right movement of the connector holder 130, and a flange portion 118b that protrudes above the top plate 134 to regulate the upward movement of the connector holder 130.

[0033] As described below, a gap is formed between the upper surface 134b of the top plate 134 of the connector holder 130 and the lower surface of the flange portion 118b, which is sufficient to allow slight vertical movement and tilt of the connector holder 130. In addition, a gap is provided between the upper opening 134a of the top plate 134 and the fitting portion 118a of the spacer 118, allowing a certain degree of forward / backward and left / right movement.

[0034] As shown in FIG. 6(c), the top plate 134 of the connector holder 130 has a left inclined surface 134c as a first inclined surface and a right inclined surface 134d as a second inclined surface formed back-to-back on its underside, with both ends positioned above the ridge portion 134e so as to form a ridge portion 134e as a swing center that is located in the center in the left-right direction (Y direction) and extends in the front-to-back direction (X direction).

[0035] Therefore, as shown in FIG. 4(c), when the connector holder 130 is attached to the upper extension portion 111a of the stay 111 by locking screws 119 via spacers 118 and in its natural state under its own weight, wedge-shaped gaps are formed between the left inclined surface 134c and the right inclined surface 134d and the upper surface of the upper extension portion 111a, respectively, which widen toward the ends.

[0036] In this embodiment, as described above, the ridge portion 134e, which is the center of oscillation, is located at the center of the width direction (arrow Y direction) of the connector holder 130, so that the connector holder 130 itself is configured so that a force that would bend the heater 121 due to gravity is unlikely to be generated.

[0037] Next, the attachment of the front connector 141 and the rear connector 142 will be described. Fig. 7 is a cross-sectional view taken along line CC in Fig. 3(a), and Fig. 8 is a diagram for explaining the operation of the present invention, showing a cross-sectional view of the vicinity of the left end portion in cross-section EE, slightly before cross-section AA in Fig. 3(a). For reference, a position corresponding to cross-section EE is shown in Fig. 7.

[0038] As shown in these figures, the front connector 141 serving as a connection part is a substantially rectangular parallelepiped member, and includes a deeply formed cutout portion 141a having a concave cross section at the rear, and a convex portion 141b at the bottom that fits with a front step portion 131b of the outer casing 131 of the connector holder 130. This front connector 141 is press-fitted into the upper through-hole 130a and the lower through-hole 130b (FIG. 6) of the connector holder 130 from the front side, while fitting the front halves of the left end portion 121a of the heater 121 disposed along the lower wall 133 and the underside of the lower wall 133 of the connector holder 130 into the cutout portion 141a.

[0039] Similarly, the rear connector 142 serving as a connection part is also a substantially rectangular parallelepiped member, and includes a deeply formed cutout portion 142a having a concave cross section in the front part, and a convex portion 142b (FIG. 8(a)) at the bottom that fits with a rear step portion 131c of the outer casing 131 of the connector holder 130. This rear connector 142 is press-fitted into the upper through-hole 130a and the lower through-hole 130b of the connector holder 130 from the rear side, while fitting the rear halves of the left end portion 121a of the heater 121 disposed along the lower wall 133 of the connector holder 130 and the underside of the lower wall 133 into the cutout portion 142a.

[0040] As a result, a front half of the left end 121a of the heater 121 is pressed against the underside of the lower wall 133 of the connector holder 130 by the front connector 141, and a rear half of the left end 121a of the heater 121 is pressed against the underside of the lower wall 133 of the connector holder 130 by the rear connector 142. Furthermore, a drive current for the heater 121 is supplied from the outside to the heater 121 via the connectors 141, 142 by electrical connection of electrical terminals (not shown) formed on each of the joint surfaces of the front connector 141 and the heater 121, and by electrical connection of electrical terminals (not shown) formed on each of the joint surfaces of the rear connector 142 and the heater 121.

[0041] Before describing the operation of the present invention, the problems of the fixing device shown as a comparative example will be described. Fig. 9 is a diagram for explaining the fixing device 100 of the present invention and the stay 111 used in the comparative example, and Fig. 13 is a cross-sectional view of the connector holder 501 and its periphery constituting the comparative example. The only difference between the fixing device 100 of the present invention and this comparative example is the shape of a part of the connector holder and the heater holder. The cross-sectional position of Fig. 13 corresponds to the cross-sectional position of Fig. 8, that is, the E-E cross-sectional position of Fig. 3. In Fig. 9, the heater 121, the thermal diffusion plate 122, and the fixing belt 110 are omitted.

[0042] As shown in Figure 13, connector holder 501 in this comparative example differs from connector holder 130 according to the present invention in that its top plate 501a is formed in a flat plate shape, does not have left and right inclined surfaces 134c, 134d (see Figure 6) like top plate 134 of connector holder 130 according to the present invention, and is firmly fixed to upper extension portion 111a of stay 111 by locking screw 119.

[0043] In the above configuration, the heater 121 is held in the vertical direction by the attached front connector 141 and rear connector 142 at the position of the connector holder 501, so as to be urged against the underside of the lower wall 133 of the connector holder 501, and at the position opposite the pressure roller 102, by being urged against the underside of the heater holder 502.

[0044] Therefore, heater 121 is biased by different members at the position of connector holder 501 and the position of pressure roller 102, and may be biased to surfaces at different heights due to dimensional variations. As a result, heater 121 is deformed by inclination as shown in Fig. 13 in the region between the position of connector holder 501 and the position of the part pressed by pressure roller 102. Also, distance L1 in the width direction (Y direction) of the region tends to become smaller as the fixing device becomes more space-saving, and in this case, it becomes more susceptible to damage.

[0045] In addition, the height between the lower surface of the lower wall 133 of the connector holder 501 and the lower surface of the heater holder 502, where the heater 121 is energized, is likely to vary since it passes through multiple parts. For example, as shown in Fig. 9(a), the contact surface 111b (see Fig. 5(b)) of the stay 111 as the pressing portion with the heater holder 502 often has a crown shape as adopted in this embodiment. The crown shape is a shape in which the center is bulged in advance so that the pressure distribution in the width direction (arrow Y direction) becomes uniform due to deformation that occurs when the pressure roller 102 and the pressure roller 102 are in a pressed state (when a nip is formed).

[0046] 9(b) is a schematic diagram emphasizing the bulge at the center to explain the crown shape. As shown in the figure, the contact surface 111b of the stay 111 with the heater holder 502 has an arc shape with the center portion 111c projecting most in at least the region in the width direction that contacts the pressure roller 102.

[0047] Therefore, the contact surface 111b becomes nearly flat when nipped (pressed), but when released from the nipped state, it returns to a crowned shape, and this state change is repeated according to the operation mode. Therefore, the heater 121, together with the heater holder 502, repeats deformation between a flat state and a crowned state in accordance with the state change of the contact surface 111b of the stay 111 via the heater holder 502.

[0048] For these reasons, the underside of the lower wall 133 of the connector holder 501 and the underside of the heater holder 502, to which the heater 121 is energized, are unlikely to always be equal in height in the Z direction and in angle with respect to the horizontal direction, and the heater 121, which deforms in accordance with each underside, is subjected to stress and becomes prone to damage.

[0049] Based on the above description of the comparative example device, the operation of the fixing device 100 according to the present invention will be described. As shown in Fig. 4(c), the movement of the top plate 134 of the outer casing 131 of the connector holder 130 is restricted with a predetermined play in the front-rear and left-right directions by the fitting portion 118a of the spacer 118 that fits into the upper opening 134a, and the movement in the up-down direction is restricted with a certain degree of play by the spacer 118 and the upper extension portion 111a of the stay 111.

[0050] Furthermore, as described above, the bottom surface of the top plate 134 is formed back-to-back such that the left inclined surface 134c and the right inclined surface 134d form the ridge portion 134e. Therefore, the connector holder 130 is configured to be able to move up and down and tilt left and right within a predetermined range.

[0051] Here, the allowable range of vertical movement and left / right tilt will be examined. In the case where the fixing device 100 is a device that can handle up to A3 portrait printing, for example, as shown in Fig. 9(b), the protrusion amount d1 of the center portion 111c of the crown-shaped contact surface 111b of the stay 111 relative to the left end portion facing the pressure roller 102 is set to 0.5 mm, and the position error in the height direction (Z direction) of the opposing surfaces of the upper extension portion 111a of the stay 111 and the flange portion 118b of the spacer 118 shown in Fig. 4(c) is assumed to be about ±0.5 mm.

[0052] Therefore, as shown in Fig. 4(c), the amount of play in the up-down direction of the connector holder 130 permitted by the spacer 118 and the upper surface extension 111a of the stay 111 is preferably about 1.0 mm, which is the sum of the two. On the other hand, as shown in Fig. 4(c) and Fig. 6(c), the connector holder 130 has a left inclined surface 134c and a right inclined surface 134d formed back-to-back on the underside of the top plate 134, which form a ridge portion 134e located at the center in the left-right direction (Y direction) and extending in the front-rear direction (X direction). This allows the connector holder 130 to move up-down with a play of about 1.0 mm and to tilt in the clockwise and counterclockwise directions.

[0053] This allows the connector holder 130 to change its position in response to changes in the shape of the heater 121.

[0054] For example, as shown in the cross-sectional view of Figure 8(a), when the underside of the lower wall 133 of the connector holder 501 is higher in the direction of arrow Z than the underside of the heater holder 502 facing the pressure roller 102, the connector holder 130 holding the left end portion 121a of the heater 121 is tilted clockwise, so that the deformation occurring in the heater 121 is mitigated by the tilt of the connector holder 130 and the load due to the deformation is also reduced.

[0055] On the other hand, as shown in the cross-sectional view of Figure 8(b), when the underside of the heater holder 502 facing the pressure roller 102 is higher in the direction of arrow Z than the underside of the lower wall 133 of the connector holder 501, the connector holder 130 holding the left end portion 121a of the heater 121 is tilted counterclockwise, so that the deformation occurring in the heater 121 is similarly mitigated by the tilt of the connector holder 130, and the load due to the deformation is also reduced.

[0056] 9(b), in the case where the fixing device 100 is a device that supports up to A3 portrait printing, for example, the protrusion amount d1 of the center portion 111c of the crown shape of the contact surface 111b of the stay 111 relative to the left end portion facing the pressure roller 102 is set to 0.5 mm. In this case, the deformation angle as the second inclination angle of the heater 121 when following this crown shape is about 0.2°, and the assumed deformation angle of the heater 121 due to the widthwise distance L1 (see FIG. 4) from the roller end of the pressure roller 102 to the connector holder 130 and a vertical position error of 0.5 mm in this region is 1.0°.

[0057] For these reasons, it is desirable to set the inclination angle θ1 (see FIG. 6), which is the first inclination angle of the left inclined surface 134c and the right inclined surface 134d of the top plate 134 of the connector holder 130 (not inclined state) shown in FIG. 4(c) with respect to the horizontal plane, to the sum of the two deformation angles mentioned above, 1.2° (0.2° + 1.0°).

[0058] From the above, the effect becomes greater as the inclination angle θ1 becomes larger than 0°, but the effect saturates at about 1.2°. On the other hand, if the inclination angle θ becomes larger than necessary, exceeding 1.2°, when the fixing device 100 is subjected to vibration or impact, the connector holder 130 becomes more likely to be displaced by the action of the front connector 141 and the rear connector 142, which may damage the heater 121. For these reasons, it is desirable that the upper limit of the inclination angle θ1 be about 10°.

[0059] FIG. 10 is an image diagram emphasizing the state of each part when connector holder 130 holding left end portion 121a of heater 121 is tilted clockwise as shown in FIG. 8(a).

[0060] As shown in the figure, when the heater 121 deforms in accordance with the crank shape of the stay 111, the connector holder 130 holding the left end 121a of the heater 121 moves up and down and tilts clockwise in accordance with the deformation of the heater 121. As a result, even though the left end of the heater 121 is held by the connector holder 130, the load caused by this is suppressed.

[0061] In this embodiment, when the heater 121 deforms to assume a crown shape as described above, tapered surface 120a is formed as a gap forming portion for forming a gap between the heater holder 120 and the heater 121 so that external pressure is not applied to the region from the left end of the pressure roller 102 to the connector holder 130. Note that, although tapered surface 120a that forms a wedge-shaped gap is formed here, it is also possible to form a gap by providing a step.

[0062] Variation 1. FIG. 11 is a conceptual diagram that illustrates a schematic configuration of the first modified example of the present embodiment.

[0063] In this embodiment, as shown in FIG. 4(c), by employing a spacer 118, movement is restricted in the front-rear, left-right, up-down directions with respect to the top extension 111a of the stay 111 while maintaining a predetermined play. However, the present invention is not limited to this. It is also possible to allow free movement in all directions by simply arranging the top extension 111a of the stay 111 so that it penetrates the insertion portion 135 formed by the left opening 131f and the right opening 131g, which are arranged to face each other through an internal space, as shown in FIG. 11.

[0064] Variation 2. FIG. 12 is a conceptual diagram that illustrates a schematic configuration of the second modification of the present embodiment.

[0065] In this embodiment, as shown in Fig. 6(c), the ridge portion 134e serving as the swing center of the connector holder 130 is formed to be located at the center in the width direction (arrow Y direction) of the connector holder 130, but is not limited to this. For example, as shown in Fig. 12(a), the ridge portion 134e serving as the swing center may be formed at a position shifted from the width direction center of the connector holder 130. Also, as shown in Fig. 12(b), the swing center may be a convex portion 134f formed in a convex shape, rather than a ridge portion formed by two inclined surfaces.

[0066] 12(c), a support portion (corresponding to ridge portion 134c) for generating rocking motion may be formed on upper surface extension portion 111a of stay 111, rather than on top plate 134 of connector holder 130. In this case, the surface of upper surface extension portion 111a facing top plate 134 of connector holder 130 may be formed in an arc shape so as to abut against top plate 134 at a portion in the direction of arrow Y, for example.

[0067] As described above, according to the fixing device of this embodiment, the load caused by the deformation of the heater 121 due to manufacturing errors or the movement of the fixing belt unit 101 between a movable position and a retracted position can be suppressed by the oscillation of the connector holder 130 that follows the deformation, so that malfunction of the heater 121 caused by repeated movement between positions, etc. can be suppressed.

[0068] In addition, in the description of the above embodiment, terms such as "upper," "lower," "left," "right," "front," and "rear" are used, but these are used for convenience and do not limit the absolute positional relationship when the fixing device is arranged. [Industrial Applicability]

[0069] In the above embodiment, an example was shown in which the present invention is applied to an image forming apparatus as a color printer, but the present invention is not limited to this and can also be used in image processing apparatuses such as copiers, facsimiles, MFPs, etc. Also, although a color printer has been described, a monochrome printer may also be used. [Explanation of symbols]

[0070] 100 fixing device, 101 fixing belt unit, 102 pressure roller, 102a rotating shaft, 110 fixing belt, 111 stay, 111a upper surface extension portion, 111b contact surface, 111c center portion, 112 left support lever, 112a left pivot hole, 112b spring receiving portion, 113 right support lever, 113a right pivot hole, 113b spring receiving portion, 114 left guide member, 114a inner guide portion, 114b left regulating portion, 115 right guide member, 115a inner guide portion, 115b right regulating portion, 116 fixing screw, 117 fixing screw, 118 spacer, 118a fitting portion, 118b flange portion, 119 locking screw, 120 heater holder, 120a tapered surface, 121 heater, 121a left end portion, 122 heat diffusion plate, 130 connector holder, 130a upper through hole, 130b lower through hole, 131 outer casing, 131b front step portion, 131c rear step portion, 131d through hole, 131e through hole, 131f left opening portion, 131g right opening portion, 132 upper wall, 133 lower wall, 133a convex portion, 134 top plate, 134a upper opening portion, 134b upper surface, 134c left inclined surface, 134d right inclined surface, 134e ridge portion, 134f convex portion, 141 front connector, 141a Notch portion, 141b convex portion, 142 rear connector, 142a notch portion, 142b convex portion, 200 rotating shaft, 501 connector holder, 501a top plate, 502 heater holder, 1000 image forming device, 1001 recording paper, 1004 paper feed cassette, 1005 paper feed roller, 1006 registration roller, 1010 developing device, 1011 photosensitive drum, 1012 charging device, 1013 exposure device, 1014 developer supply device, 1015 cleaning device, 1020 transfer device, 1021 endless transfer belt, 1022 drive roller, 1023 tension roller, 1030 transport roller, 1031 transport roller, 1032 Paper output stacking section.

Claims

1. A first rotor extending in a first direction; a second rotating body extending in the first direction and disposed to face the first rotating body and form a nip portion; a heating section extending in the first direction and configured to heat the first rotating body; A support extending in the first direction and supporting the heating unit; a biasing mechanism that biases the support body so as to bias the heating portion against the second rotating body; A connection part electrically connected to the heating part; a holding part that holds the connection part to maintain electrical connection with the heating part and is supported to be swingable relative to the support; A fixing device comprising:

2. The holding portion is 2. The fixing device according to claim 1, wherein a pivot center extends in a direction intersecting the first direction and is supported pivotally relative to the support.

3. The holding portion is 3. The fixing device according to claim 1, wherein the fixing member is supported so as to be movable in the first direction relative to the support.

4. the first rotating body is a circular belt extending in the first direction, the support body has a first exposed portion protruding outside the first rotating body in the first direction, the heating portion has a second exposed portion protruding to an outside of the first rotating body in the first direction, the connection portion is connected to the second exposed portion of the heating portion, 3. The fixing device according to claim 1, wherein the holding portion holds the second exposed portion and is supported by the first exposed portion.

5. the support body has a first exposed portion protruding outside the first rotating body in the first direction, The holding portion has an insertion portion that forms a cavity extending in a first direction, the first exposed portion is inserted into the insertion portion and abuts against the holding portion at a portion in the first direction; 2. The fixing device according to claim 1, wherein the holding portion is supported so as to be capable of swinging freely.

6. 3. The fixing device according to claim 2, wherein the pressing portion of the support that presses the heating portion has a shape such that the center side protrudes toward the second rotating body from the end portion at least in the region facing the second rotating body in the first direction.

7. The fixing device described in claim 6, characterized in that the swing center of the holding portion corresponds to a ridge portion formed by a first inclined surface and a second inclined surface arranged on the first rotating body side and formed adjacent to each other in the first direction on the surface facing the support, and a first inclination angle of the first inclined surface with respect to the first direction is greater than a second inclination angle of an inclined surface including an end of the pressing portion on the holding portion side of the region facing the second rotating body and a maximum protrusion portion of the protruding shape with respect to the first direction.

8. an intermediate member interposed between the support body and the heating unit and in contact with the heating unit; 3. The fixing device according to claim 1, wherein the intermediate member has a gap forming portion at an end portion on the side of the holding portion for forming a predetermined gap between the intermediate member and the heating portion.

9. 3. The fixing device according to claim 1, wherein the biasing mechanism is capable of displacing the support between a first state in which the first rotating body and the second rotating body form a nip portion, and a second state in which the first rotating body and the second rotating body are separated from each other.

10. 3. The fixing device according to claim 2, wherein the pivot center is located at a center of the holding portion in the first direction.

11. 3. An image forming apparatus comprising the fixing device according to claim 1.

Images