fixing unit

Abstract

The fixing unit includes: a fixing belt; a heater including a substrate, a heating resistor, and electrodes; a retainer; and a power connector configured to supply power to the heater, the power connector including: contacts configured to contact the electrodes; and a housing configured to receive the contacts. The retainer is integrally formed with a retaining portion configured to prevent the power connector from detaching from the heater. The contacts include: a first portion configured to contact the electrodes; and a second portion configured to clamp the heater and the retainer together with the first portion. When viewed along a longitudinal direction, the contacts have a rectangular shape with an opening on one side.

Description

Technical Field

[0001] This disclosure relates to a fixing unit installed on the imaging device of an electrophotographic system. Background Technology

[0002] The fixing unit described in Japanese Patent Application Publication No. H11-345680 includes: a heating unit having a heater and an inner surface of a heating band; and a pressure roller that forms a clamping portion with the heater via a fixing film, thereby fixing the toner onto the recording material. A power connector is arranged in the heating unit, and contact members that engage with an electrode portion connected to a current-carrying heating resistor layer of the heater are arranged in the power connector. Summary of the Invention

[0003] According to one aspect of this disclosure, a fixing unit includes a fixing belt, a heater, a retainer, and a power connector. The fixing belt is tubular. The heater includes: a substrate having a plate shape; a heating resistor disposed on the substrate; and an electrode electrically connected to the heating resistor and disposed at an end portion in the longitudinal direction of the substrate. The heater is disposed within an internal space of the fixing belt. The retainer is disposed within the internal space of the fixing belt and configured to retain the heater in its longitudinal direction. The power connector is configured to supply power to the heater and includes: a contact configured to contact the electrode and having conductivity; and a housing configured to receive the contact. The fixing unit is configured to fix a toner image formed on a recording material via the fixing belt using the heat of the heater. The retainer is integrally formed with a retaining portion configured to prevent the power connector from detaching from the heater. The contact includes: a first portion configured to contact the electrode; and a second portion configured to clamp the heater and the retainer together with the first portion. When viewed along the longitudinal direction, the contact point has a rectangular shape with an opening on one side.

[0004] The features of this disclosure will become clear from the following description of embodiments with reference to the accompanying drawings. The following description of the embodiments is by way of example. Attached Figure Description

[0005] Figure 1 This is a cross-sectional view showing an imaging device according to Example 1.

[0006] Figure 2 This is a cross-sectional view showing the fixing unit according to Example 1.

[0007] Figure 3 This is a cross-sectional view showing the fixing unit according to Example 1.

[0008] Figure 4 This is an exploded perspective view showing the fixing unit according to Example 1.

[0009] Figure 5 This is a top view showing the retainer according to Example 1.

[0010] Figure 6 This is an exploded perspective view showing the retainer, temperature sensor, push member, and bracket according to Example 1.

[0011] Figure 7 This is a bottom view showing the heater, retainer, and belt according to Example 1.

[0012] Figure 8 This is a bottom view showing the heater according to Example 1.

[0013] Figure 9A This is a perspective view showing the state immediately preceding the installation of the connector according to Example 1 into the retainer.

[0014] Figure 9B This is a perspective view showing the connector already installed in the retainer.

[0015] Figure 10 It is a cross-sectional view showing a section taken along a plane perpendicular to the Y direction of the retainer and contacts according to Example 1.

[0016] Figure 11A It is a cross-sectional view showing a section taken along a plane perpendicular to the Z direction of the retainer and contacts according to Example 2.

[0017] Figure 11B It is a cross-sectional view showing a section taken along a plane perpendicular to the Y direction of the retainer and contacts according to Example 2. Detailed Implementation

[0018] In the following description, embodiments of the present disclosure will be presented based on the accompanying drawings. It should be noted that the dimensions, materials, shapes, relative arrangements, etc., of the components described in the examples below may be appropriately modified according to the construction of the device to which the present disclosure is applied and various circumstances. Therefore, unless specifically stated otherwise, the scope of this disclosure is not limited to the examples described herein.

[0019] Figure 1 This is a cross-sectional view of an imaging device 1 that uses the fixing unit 6 in this example of an electrophotographic system. It should be noted that in the following description, as... Figure 1As shown, the clamping direction in the clamping portion np1 of the fixing unit 6 (described later) is called the Z direction. The direction intersecting the Z direction is called the Y direction. The Y direction is parallel to the rotation axis direction of the pressure rotating member 62 (described later). The direction intersecting both the Z and Y directions is called the X direction. The X direction is parallel to the direction in which the heating unit 61 conveys the recording material located at the clamping portion (described later). The X and Y directions are preferably horizontal. Furthermore, the X, Y, and Z directions are preferably perpendicular to each other. Additionally, as needed, the arrows X, Y, and Z directions shown in the figures are referred to as +X, +Y, and +Z directions, respectively, and the opposite directions are referred to as -X, -Y, and -Z directions, respectively. In the following description, the direction in which the sheet S used as recording material is conveyed at the clamping portion np1 (described later) is called the recording material conveying direction (+X direction). Additionally, the rotation axis direction of the pressure rotating member 62 (described later) is called the axial direction. In the axial direction, the direction from the transmission member 617b to the transmission member 617a (described later) is called the first axial direction (+Y direction). In the axial direction, the direction opposite to the first axial direction is called the second axial direction (-Y direction). The Y direction is also the longitudinal direction of the heating unit 61. In addition, the Y direction is the generatrix direction of belt 614.

[0020] Example 1

[0021] Construction of imaging equipment

[0022] Will use Figure 1 The construction of the imaging device 1 according to Example 1 is described. The imaging device 1 includes a device body 2, a processing cartridge 10, and a fixing unit 6. The processing cartridge 10 is detachably attached to the device body 2. The fixing unit 6 is detachably attached to the device body 2. Alternatively, the fixing unit 6 can be said to be mounted relative to the device body 2. It should be noted that the fixing unit 6 can also be attached in a non-detachable manner.

[0023] The device body 2 includes a sheet feed tray 3, a sheet feed unit 4, a conveying path P, a transfer roller 51, a sheet discharge unit 7, a sheet discharge tray 8, a laser scanner 9, and an opening / closing door 21. The processing cartridge 10 includes a photosensitive drum 11 and a developing roller 12, which serves as a developer carrier. Additionally, the processing cartridge 10 stores developer internally. The opening / closing door 21 is pivotally supported about a pivot axis 21a as a center and is configured to move between a closed position (closing the opening portion 2a) and an open position (opening the opening portion 2a). When the opening / closing door 21 is in the open position (opening the opening portion 2a), the processing cartridge 10 can be attached to and detached from the device body 2 via the opening portion 2a.

[0024] The sheet feeding unit 4 consists of a sheet feeding roller 41, a separation roller 42, a separation pad 42a, and a transfer roller pair 43. Based on the printing start signal, the sheet S stored in the sheet feeding tray 3 is sent to the transfer path P through the sheet feeding unit 4 and is transferred to the transfer roller 51 via the alignment roller pair 44.

[0025] When the sheet S is conveyed to the predetermined position, an imaging start signal is sent, and imaging processing begins. The photosensitive drum 11, rotatably driven by a drive source (motor) (not shown), is uniformly charged to a predetermined potential by a charging device (not shown). The surface of the charged photosensitive drum 11 is exposed by a laser scanner 9 based on image information, forming an electrostatic latent image from which the charge has been removed from the exposed area. Toner in the processing cartridge 10, carried by the developing roller 12, is supplied to the photosensitive drum 11 according to the electrostatic latent image; thereby developing the latent image. Thus, the latent image is visualized as a toner image on the photosensitive drum 11.

[0026] The transfer roller 51 is arranged to face the photosensitive drum 11, which is included in the processing cartridge 10. When the sheet S, conveyed by the alignment roller pair 44, passes through the clamping portion between the photosensitive drum 11 and the transfer roller 51, voltage is applied from the device body 2 to the transfer roller 51, and the toner image on the photosensitive drum 11 is transferred onto the sheet S as an unfixed image. Then, the sheet S with the toner image transferred is conveyed to the fixing unit 6, which is equipped with a heating unit 61 and a pressure rotation member 62. The fixing unit 6 is a fixing unit that fixes the toner image (developer image) onto the recording material.

[0027] As the sheet S passes through the clamping portion of the heating unit 61 and the pressure rotating member 62, the unfixed image transferred onto the sheet S is heated and pressurized, and fixed onto the surface of the sheet S. The sheet S with the fixed toner image is then discharged into the sheet discharge tray 8 via the sheet discharge unit 7.

[0028] Construction of fixing unit

[0029] The construction of fixing unit 6 will be described below. Figure 2 This is a cross-sectional view showing the fixing unit 6. (Example) Figure 2 As shown, the heating unit 61 includes a heater 611, a holder 612, a support 613, and a belt 614 (also referred to as a fixing film) serving as a fixing belt. The heater 611 is disposed within the interior space of the belt 614 and heats the belt 614. The heater 611 extends along the generatrix direction (Y direction) of the belt 614, and the heater 611 is constructed in a plate shape. The heater 611 includes a first surface 611a and a second surface 611b, the second surface 611b being on the side opposite to the first surface 611a, and the first surface 611a is held by the holder 612. The holder 612 holds the heater 611 along its longitudinal direction (Y direction).

[0030] The retainer 612 is made of a heat-resistant resin (e.g., polyphenylene sulfide (PPS) or a liquid crystal polymer) and includes a guide surface 612a and a support wall 612b. The guide surface 612a guides the belt 614 by contacting the inner circumferential surface 614a of the belt 614, and the support wall 612b includes a support surface 612b1 supporting the heater 611. The support surface 612b1 of the support wall 612b contacts the first surface 611a of the heater 611. The bracket 613 is a component that supports the retainer 612 and is formed by bending a plate material with higher rigidity than the retainer 612 (e.g., a steel plate with a thickness of 1.6 mm) into a basic U-shaped structure.

[0031] The belt 614 is an annular belt forming a tubular structure and possesses heat resistance and flexibility; for example, the belt 614 is constructed from a metal sleeve (e.g., stainless steel) coated with fluororesin or a laminate of polyimide resin, silicone rubber, fluororesin, etc. The heater 611, retainer 612, and support 613 are arranged within the internal space of the belt 614, and the belt 614 is configured to rotate about these components. The inner circumferential surface 614a of the belt 614 contacts the second surface 611b of the heater 611.

[0032] The pressure rotating member (pressure roller) 62 includes a metal shaft 62a and a roller 62b formed of an elastic material covering the shaft 62a, and is pressed onto the heater 611 via a belt 614. The pressure rotating member 62 forms a clamping portion np1 by clamping the belt 614 with the heater 611, for heating and pressurizing the sheet S by clamping. In other words, it can be said that the pressure rotating member (pressure roller) 62 forms the clamping portion np1 together with the heater 611 via the belt 614. That is, the pressure rotating member 62 heats and pressurizes the sheet S together with the heater 611 at the clamping portion np1.

[0033] The pressure-rotating member 62 is configured to rotate when a driving force from a drive source (including the imaging device 1) is transmitted. As the pressure-rotating member 62 rotates, the belt 614 is driven to rotate. The toner image is thermally fixed as the sheet S on which the toner image has been transferred is conveyed between the pressure-rotating member 62 and the heated belt 614.

[0034] The following will use Figure 3 Describe the frame structure of fixing unit 6. Figure 3This is a cross-sectional view showing the fixing unit 6. The fixing unit 6 includes an upper frame 64 and a lower frame 63. It should be noted that the lower frame 63 and the upper frame 64 can also be referred to as the first frame and the second frame, respectively. The lower frame 63 is a frame that supports the heating unit 61 and the pressure rotating member 62. The upper frame 64 is located on top of the lower frame 63 and covers the heating unit 61. The lower frame 63 and the upper frame 64 are resin members formed from non-conductive molding members (resin members). The upper frame 64 includes an upper guide surface 64a arranged downstream of the heating unit 61 in the recording material transport direction (+X direction). The upper guide surface 64a guides the upper surface of the sheet S conveyed along the recording material transport direction. The lower frame 63 includes a lower guide surface 63a arranged downstream of the heating unit 61 in the recording material transport direction. The lower guide surface 63a guides the lower surface of the sheet S conveyed along the recording material transport direction.

[0035] The following uses Figure 4 The structure of the lower frame 63 supporting the pressurized rotating member 62 is described below. Figure 4 This is an exploded perspective view showing the fixing unit 6. The lower frame 63 includes tracks 63b at each end portion in a first axial direction and a second axial direction. The tracks 63b extend vertically and support the retainer 612 in a manner that allows vertical movement. Each of the two tracks 63b is arranged opposite the other track in the axial direction. The tracks 63b engage with slots 617a1 and 617b1 respectively arranged in the transmission members 617a and 617b.

[0036] The fixing unit 6 includes bearings 62c and 62d. The end portions of shaft 62a in the first and second axial directions are supported by bearings 62c and 62d, respectively. Bearing 62c includes a protrusion 62c1, which is positioned when fitted into a recess 63d1 arranged in the lower frame 63. Similarly, bearing 62d includes a protrusion 62d1, which is positioned when fitted into a recess 63d2 arranged in the lower frame 63. It should be noted that bearing 62c is conductive. It should be noted that in this configuration, protrusions 62c1 and 62d1 are arranged in bearings 62c and 62d, and recesses 63d1 and 63d2 are arranged in the lower frame 63; however, the protrusion-recession relationship can be reversed. Furthermore, the means for fixing bearings 62c and 62d to the lower frame 63 are not limited to a protrusion-recession configuration.

[0037] Figure 5 This is a top view showing the retainer 612. Figure 5 This is a view of the retainer 612 viewed along the -Z direction. Figure 6 This is an exploded perspective view showing the retainer 612, temperature sensors 613a and 613b, push members 613c and 613d, and bracket 613. Figure 5 As shown, the support wall 612b of the retainer 612 includes a plurality of holes 612b2 and 612b3.

[0038] like Figure 6 As shown, temperature sensors 613a and 613b are arranged facing a rear surface 612b4, which is on the opposite side of the support surface 612b1 of the retainer 612. Temperature sensors 613a and 613b contact the first surface 611a of the heater 611 through holes 612b2 and 612b3. Temperature sensors 613a and 613b are pressed against the first surface 611a of the heater 611 by push members 613c and 613d arranged between the bracket 613 and the temperature sensors 613a and 613b (see Figure 1). Figure 2 The temperature sensor 613a is located on one side of the end portion of the holder 612 in the longitudinal direction.

[0039] The center of temperature sensor 613b in the longitudinal direction (Y direction) relative to retainer 612 is located on one side. In this example, temperature sensors 613a and 613b are thermistors, but other temperature sensors, such as thermostats, could also be used. In this example, the push member is a helical spring, but other push members could also be used.

[0040] Figure 7 This is a bottom view showing the heater 611, retainer 612, and belt 614. Figure 4 and Figure 7 As shown, the retainer 612 extends through the interior of the strip 614 in the longitudinal direction (Y direction), and its two end portions in the longitudinal direction protrude outward from the strip 614. The retainer 612 supports the heater 611, and a connector 616 is arranged on one side of the end portion of the heater 611 in the longitudinal direction. The connector 616 serves as a power connector to supply power to the heater 611 and to clamp the heater 611 and the retainer 612.

[0041] It should be noted that in this example, the pressure-rotating member 62 includes a shaft 62a and a roller 62b; however, it is not limited to this. For example, instead of the pressure-rotating member 62, a pressure belt can be used, which is pressed against the belt 614 of the heating unit 61.

[0042] heater

[0043] Figure 8 This is a bottom view showing heater 611. (As shown) Figure 8As shown, the heater 611 includes: a plate-shaped substrate 900 extending in a longitudinal direction (Y direction); and heating resistors 901a and 901b mounted on the substrate 900 and arranged in the longitudinal direction. Conductors 902a to 902c are connected to two end portions of the two heating resistors 901a and 901b in the longitudinal direction.

[0044] The first end of conductor 902a is connected to electrode 903a, which is used as a heating resistor, and the second end of conductor 902a is connected to heating resistor 901a. The first end of conductor 902b is connected to heating resistor 901a, and the second end of conductor 902b is connected to heating resistor 901b. The first end of conductor 902c is connected to heating resistor 901b, and the second end of conductor 902c is connected to electrode 903b, which is used as a heating resistor. That is, electrodes 903a and 903b are electrically connected to heating resistors 901a and 901b. Therefore, by allowing current to flow between electrodes 903a and 903b, a heater circuit structure is established that allows heating resistors 901a and 901b to generate heat simultaneously.

[0045] Here, the centerline in the short direction (X direction) of electrode 903a is called centerline 903c, the centerline in the short direction (X direction) of electrode 903b is called centerline 903d, and the centerline in the short direction (X direction) of heater 611 is called centerline c1. In this case, the centerlines 903c and 903d of electrodes 903a and 903b are located upstream of centerline c1 of heater 611 in the mounting direction (-X direction) of connector 616. It should be noted that it is sufficient for at least one of the centerlines 903c and 903d of electrodes 903a and 903b (not both 903c and 903d) to be located upstream of centerline c1 in the mounting direction (-X direction) of connector 616. Centerline 903c is an example of a first centerline, and centerline c1 is an example of a second centerline.

[0046] connector

[0047] Figure 9A This is a perspective view showing the state immediately preceding the installation of connector 616 into retainer 612. Figure 9B This is a perspective view showing the connector 616 installed in the retainer 612. (As shown) Figure 9AAs shown, connector 616 is mounted in the first end portion of retainer 612 in the +Y direction along a direction from one side of heater 611 in the shorter direction (X direction) toward the other side. That is, connector 616 is mounted relative to retainer 612 in the -X direction. With connector 616 mounted in retainer 612, the width direction of connector 616 is the same as the longitudinal direction (i.e., Y direction) of heater 611.

[0048] Connector 616 includes: a housing 904 and an arm 905, both made of a non-conductive material (e.g., resin); and a contact 906 formed of a conductive material (e.g., metal). A claw 907 is attached to the arm 905.

[0049] like Figure 9B As shown, the housing 904 has a configuration that clamps the retainer 612 and the heater 611 in the longitudinal direction (Y direction) when the connector 616 is mounted in the retainer 612. The housing 904 includes: a first side surface 904A and a second side surface 904B that extend to intersect the Y direction; and a first extension portion 904C and a second extension portion 904D that extend along the -X direction from each of the first side surface 904A and the second side surface 904B toward the heater 611.

[0050] like Figure 9A and 9B As shown, arm 905 is located downstream of housing 904 in the +Z direction (the +Z direction is perpendicular to the mounting direction (-X direction) of connector 616) and extends along the mounting direction (-X direction) of connector 616. Arm 905 is arranged near the center of connector 616 in the width direction (Y direction) of connector 616. Arm 905 is configured such that a first end in the mounting direction is connected to housing 904, and a second end is configured to be elastically bent toward housing 904.

[0051] like Figure 9A and 9B As shown, a claw 907 is formed near the center of the arm 905 in the mounting direction (-X direction) to protrude in a direction away from the housing 904. The claw 907 includes: an upright surface 907a that rises in the +Z direction to be positioned away from the housing 904; and an inclined surface 907b that is arranged downstream of the upright surface 907a in the -X direction. The inclined surface 907b is formed to approach the arm 905 as it extends in the -X direction (the mounting direction of the connector 616).

[0052] The wall of the retainer

[0053] The retainer 612 also includes a pair of wall portions 908, a connecting wall portion 909, and a connecting portion 910, which connects the pair of wall portions 908. The pair of wall portions 908, the connecting wall portion 909, and the connecting portion 910 are integrally formed at the end portion of the retainer 612 in the +Y direction.

[0054] The pair of walls 908 are facing each other in the Y direction (the Y direction is perpendicular to the mounting direction (-X direction) of the connector 616). The pair of walls 908 are arranged to clamp the connector 616 between them when it is mounted in the retainer 612. In the longitudinal direction (Y direction) of the heater 611, the spacing between the pair of walls 908 is slightly greater than the length of the connector in the width direction (Y direction). The pair of walls 908 consists of a wall 908A serving as a first wall and a wall 908B serving as a second wall, the second wall being arranged downstream of wall 908A in the -Y direction. When the connector 616 is mounted in the retainer 612, wall 908A faces the first side surface 904A of the housing 904, and wall 908B faces the second side surface 904B of the housing 904.

[0055] The connecting wall 909 is a wall that connects the downstream end portions of the pair of wall portions 908 (908A, 908B) in the mounting direction (-X direction).

[0056] The connecting portion 910 is arranged such that the upstream end portions of the pair of wall portions 908 are connected to each other in the mounting direction (-X direction). Additionally, a retaining portion 911 is arranged near the center in the Y direction of the connecting portion 910, which serves as a retaining device to prevent the connector 616 from disengaging. That is, the retaining portion 911, serving as the first retaining portion, is integrally formed in the retainer 612.

[0057] like Figure 9B As shown, when the connector 616 is installed into the retainer 612, the arm 905 elastically bends to approach the housing 904. At this time, the inclined surface 907b of the claw portion 907 arranged on the arm 905 slidably engages the lower surface of the connecting portion 910. Then, when the connector 616 is installed into the retainer 612, the arm 905 elastically returns, and the claw portion 907 contacts the retaining portion 911 of the retainer 612. At this time, when engaging with the upright surface 907a of the claw portion 907, the retaining portion 911 restricts the movement of the connector 616 towards the upstream side (i.e., along the +X direction) in the installation direction.

[0058] Additionally, the housing 904 enters the state where the first end portions of the heater 611 and the holder 612 in the longitudinal direction are clamped by the first and second extension portions 904C and 904D via the contacts 906, respectively.

[0059] When the connector 616 is removed from the retainer 612, the operator applies downward pressure to elastically deform the arm 905. This releases the engagement between the upright surface 907a of the claw 907 and the retaining portion 911, allowing the connector 616 to be moved in a removal direction (+X direction) opposite to the mounting direction. Therefore, the connector 616 can be removed from the retainer 612.

[0060] Description of rectangular single-sided opening contact

[0061] Figure 10 This is a cross-sectional view showing a section taken along a plane perpendicular to the Y direction of contact 906. (See attached image.) Figure 10 As shown, inside connector 616, when viewed along the longitudinal direction, contact 906 has a rectangular shape (rectangular U-shaped cross-section) with an opening on one side. Contact 906 includes a surface serving as a first part (i.e., spring pressure surface 912) and a pressure receiving surface 913 serving as a second part, which are arranged to face each other in the Z direction.

[0062] A spring pressure surface 912 is arranged downstream of the pressure receiving surface 913 in the -Z direction and contacts the electrodes 903a and 903b of the heating resistor used in the heater 611 using spring pressure. Furthermore, the pressure receiving surface 913 is configured to receive the pressure applied to the heater 611 by the spring pressure surface 912 via the retainer 612. In other words, the contact 906 is configured to clamp the heater 611 and the retainer 612 between the spring pressure surface 912 and the pressure receiving surface 913, and with this configuration, the positions of the contact 906 and the retainer 612 are fixed, so that they will not shift even when subjected to external disturbances. Additionally, the spring pressure surface 912 and the pressure receiving surface 913 are integrally formed as a single component, and the contact 906 has a rectangular shape with an opening on one side when viewed in the longitudinal direction.

[0063] The effect of Example 1

[0064] According to Example 1 above, the positional relationship between contact 906, connector housing 904, and retainer 612 can be ensured. When claw 907 and retaining portion 911 engage, the positional relationship between housing 904 and retainer 612 is fixed. This positional relationship between contact 906 and retainer 612 is ensured by a configuration in which heater 611 and retainer 612 are clamped between spring pressure surface 912 of contact 906 and pressure receiving surface 913 integrally formed with spring pressure surface 912, contact 906 having a rectangular shape with an opening on one side. This configuration prevents contact 906 from easily detaching from retainer 612.

[0065] Furthermore, if the connector 616 is displaced relative to the heater 611, there is a risk that the spring pressure surface 912 of the contact 906 may detach from the electrodes 903a and 903b. However, according to Example 1, relative to the short direction (X direction) of the heater 611, the center lines 903c of the electrodes 903a and 903 of the electrodes 903b are located upstream of the center line c1 of the heater 611 in the mounting direction (-X direction) of the connector 616. Additionally, since the claw 907 engages with the retaining portion 911, upstream displacement of the connector 616 relative to the heater 611 in the mounting direction (-X direction) of the connector 616 is limited. Therefore, detachment of the spring pressure surface 912 of the contact 906 from the electrodes 903a and 903b can be suppressed. Moreover, downstream displacement of the connector 616 relative to the heater 611 in the mounting direction of the connector 616 is limited by the connecting wall portion 909 of the retainer 612. Therefore, the spring pressure surface 912 of contact 906 can be prevented from disengaging from electrodes 903a and 903b.

[0066] It should be noted that when the retainer 612 and the retaining portion 911 are not integrally molded but formed as separate components, and the retainer 612 and the retaining portion 911 are to be engaged, the positions of the retainer 612 and the retaining portion 911 may become misaligned. Since the connector 616 engages with the retaining portion 911, the positions of the connector 616 and the retainer 612 will also be misaligned when the retainer 612 and the retaining portion 911 are misaligned. As a result, the contact positions between the spring pressure surface 912 and the electrodes 903a and 903b become misaligned. However, in the fixing unit 6 of this example, the retainer 612 and the retaining portion 911 are formed integrally. Therefore, the effect of the deviation in the contact positions between the spring pressure surface 912 and the electrodes 903a and 903b caused by the aforementioned misalignment of the retainer 612 and the retaining portion 911 can be reduced.

[0067] Example 2

[0068] Example 2 of this disclosure will now be described. Example 2 differs from Example 1 in that the retaining portion 917 and the protrusion 914 are respectively added to the housing 904 and contact 906 of Example 1. Therefore, constructions similar to those in the example will be omitted from the figures, or will be described by using the same reference numerals in the figures.

[0069] Figure 11A It is a cross-sectional view showing the retainer 612 and the contact 906 taken along a plane perpendicular to the Z direction. Figure 11B This is a cross-sectional view showing the retainer 612 and contact 906 taken along a plane perpendicular to the Y direction. (See attached image.) Figure 11A and 11B As shown, after crimping the power supply cable 915 with the crimping portion 916, the contacts 906 of the connector 1616, which serves as the power connector according to Example 2, are installed into the housing 904. A retaining portion 917, which serves as a second retaining portion, is arranged in the housing 904, and a plurality of (four in this example) slots 917a are formed in the retaining portion 917.

[0070] A plurality of protrusions 914 (four in this example) capable of engaging with the plurality of slots 917a of the retaining portion 917 are arranged on the contact 906. When the protrusions 914 of the contact 906 engage with the slots 917a of the retaining portion 917, the contact 906 is prevented from disengaging from the housing 904 in the disassembly direction (+X direction) opposite to the installation direction (-X direction) after the contact 906 is installed into the housing 904. The protrusions 914 are substantially arranged at the center portion of the contact 906 in the Z direction to prevent the contact 906 from tilting inside the housing 904. In addition, the slots 917a and protrusions 914 of the retaining portion 917 extend in the X direction and also engage with each other in the Y direction. Therefore, the position of the contact 906 relative to the housing 904 in the Y direction is also determined. It should be noted that although four slots and four protrusions of the retaining portion 917 are arranged in this example, it is not a limitation. For example, the number of grooves 917a and protrusions 914 can be one to three or more.

[0071] Furthermore, to minimize the size of connector 1616, the retaining portion 917 is positioned upstream in the mounting direction (-X direction) of the portion indicated by line c2 (where the claw 907 and retaining portion 911 engage). In other words, when connector 1616 is viewed in the longitudinal direction (Y direction) while mounted in retainer 612, retaining portion 917 is positioned upstream of retaining portion 911 in the mounting direction (-X direction). Moreover, if contact 906 extends too upstream in the mounting direction (-X direction), it would result in an increase in the size of contact 906. Therefore, the protrusion 914 of contact 906 is preferably positioned downstream in the mounting direction (-X direction) of the crimping portion 916 of crimping power supply cable 915, as shown by line c3.

[0072] The effect of Example 2

[0073] According to Example 2 above, when the retaining portion 917 of the housing 904 and the protrusion 914 of the contact 906 engage, the contact 906 in the housing 904 mounted to the connector 1616 is fixed relative to the housing 904. Therefore, the positional relationship between the contact 906, the housing 904, and the retainer 612 can be secured more firmly than in Example 1.

[0074] Other embodiments

[0075] It should be noted that although in the above example the second surface 611b of the heater 611 is in direct contact with the inner circumferential surface of the belt 614, it is not limited to this. For example, the heater 611 may contact the inner circumferential surface of the belt 614 via a sheet material with high thermal conductivity (e.g., an iron alloy or aluminum). Even if such a sheet material is arranged between the heater 611 and the belt 614, the pressure rotating member 62 will clamp the belt 614 together with the heater 611.

[0076] Additionally, although the strip 614 is arranged in the heating unit 61 in the above example, an annular membrane can be used instead of the strip 614. Furthermore, the fixing unit 6 can be configured such that the heating unit 61 applies pressure relative to the pressure rotating member 62, or alternatively, the pressure rotating member 62 applies pressure relative to the heating unit 61.

[0077] According to this disclosure, a novel structure for a fixing unit can be provided that is superior to conventional techniques.

[0078] Although this disclosure has been described with reference to embodiments, it should be understood that this disclosure is not limited to the disclosed embodiments. The scope of the following claims should be interpreted in the broadest sense to cover all such variations and equivalent structures and functions.

Claims

1. A fixing unit, comprising: Fixing belt, wherein the fixing belt is tubular; Heater, the heater comprising: Substrate, the substrate having a plate shape; Heating resistor, the heating resistor being disposed on the substrate; and An electrode, which is electrically connected to the heating resistor, is disposed at the end portion of the substrate in the longitudinal direction, and the heater is disposed in the internal space of the fixing belt; A retainer, the retainer being disposed within the internal space of the fixing belt and configured to retain the heater along its longitudinal direction; and A power connector configured to supply power to the heater, the power connector comprising: A contact, the contact being configured to contact the electrode, the contact being conductive; and A housing configured to accommodate the contacts; The fixing unit is configured to fix the toner image formed on the recording material using the heat from the heater via the fixing belt; The retainer is integrally formed with the retaining portion, and the retaining portion is configured to prevent the power connector from detaching from the heater; The contacts include: A first portion, the first portion being configured to contact the electrode; and The second part, configured to clamp the heater and the retainer together with the first part; and When viewed along the longitudinal direction, the contact point has a rectangular shape with an opening on one side.

2. The fixing unit according to claim 1, wherein, The housing includes a first side surface and a second side surface intersecting the longitudinal direction. The retainer includes a first wall portion facing the first side surface and a second wall portion facing the second side surface, and When the power connector is installed in the retainer, the power connector is located between the first wall portion and the second wall portion of the retainer.

3. The fixing unit according to claim 2, wherein, The retainer includes a connecting portion that connects the first wall portion and the second wall portion, and the retaining portion is disposed on the connecting portion.

4. The fixing unit according to claim 3, wherein, When the retaining portion of the retainer is referred to as the first retaining portion, the housing includes a second retaining portion, the second retaining portion being configured to prevent the contacts from disengaging from the housing towards the upstream side in the mounting direction of the power connector, and Wherein, when the power connector is installed in the retainer and viewed in the longitudinal direction, the second retaining portion is located upstream of the first retaining portion in the installation direction.

5. The fixing unit according to claim 4, wherein, The contact is provided with a crimping portion, which is configured to crimp the power supply cable connected to the contact. The second retaining portion is located downstream of the crimping portion in the mounting direction of the power connector.

6. The fixing unit according to any one of claims 1 to 5, wherein, The heater is configured such that, in the mounting direction of the power connector, the first center line of the electrode in the short direction is located upstream of the second center line in the short direction of the substrate.

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