Fixing device

Abstract

To provide a fixing device that can suppress failure of temperature sensors. [Solution] The fixing device 80 can be mounted on the main body housing of the image forming apparatus. The fixing device 80 includes a heating element 81 having a heater, a pressure roller 82, a first temperature sensor S1 and a second temperature sensor S2 for detecting the temperature of the heating element 81, a fixing connector 150 that can be connected to the main body connector of the main body housing, a relay board 240 that relays the signal from the first temperature sensor S1 to the fixing connector 150 and the signal from the second temperature sensor S2 to the fixing connector 150, a first side frame 210 arranged on one side of the heating element 81 in the longitudinal direction, a second side frame 220 arranged on the other side of the heating element 81 in the longitudinal direction, and a connecting frame 230 that connects the first side frame 210 and the second side frame 220 and is connected to the ground of the main body housing. The ground of the relay board 240 is electrically connected to the connecting frame 230.

Description

Technical Field

[0001] The present invention relates to a fixing device.

Background Art

[0002] Conventionally, as a fixing device that can be attached to the main body casing of an image forming apparatus, there is known one including a plurality of temperature sensors, a fixing connector that can be connected to the main body connector of the image forming apparatus, and a relay board that relays signals from the temperature sensors to the fixing connector (Patent Document 1).

Prior Art Documents

Patent Documents

[0003] [[ID=2I]]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when electrostatic discharge occurs between the fixing connector and the main body connector when the fixing device is attached to the main body casing, there is a possibility that the temperature sensors connected to the relay board may malfunction. Therefore, it is desired to be able to suppress malfunctions of the temperature sensors.

Means for Solving the Problems

[0005] The fixing device is attachable to the main body casing of an image forming apparatus. The fixing device includes a heating member, a pressure member, a first temperature sensor, a second temperature sensor, a fixing connector, a relay board, a first side frame, a second side frame, and a connection frame. The heating member extends in the longitudinal direction and has a heater. The pressure member extends in the longitudinal direction and nips a sheet with the heating member. The first temperature sensor detects the temperature of the heating member. The second temperature sensor detects the temperature of the heating element. The second temperature sensor is positioned differently from the first temperature sensor in the longitudinal direction. The fixing connector can be connected to the main unit connector on the main unit housing. The relay board relays the signal from the first temperature sensor to the fuser connector, and also relays the signal from the second temperature sensor to the fuser connector. The first side frame is positioned on one side of the heating element in the longitudinal direction. The second side frame is positioned on the other side of the heating element in the longitudinal direction. The connecting frame connects the first side frame and the second side frame. The connecting frame is made of metal. The connecting frame is connected to the ground of the main enclosure. The ground of the relay board is electrically connected to the connecting frame.

[0006] The ground of the relay board is electrically connected to the connection frame, which is connected to the ground of the main unit housing. This allows static electricity to be discharged through the connection frame when static electricity discharge occurs between the fuser connector and the main unit connector when the fuser device is mounted to the main unit housing. This helps to suppress failure of the temperature sensor.

[0007] The fixing connector may have a fixing ground terminal, and the main unit connector may have a main unit ground terminal connected to the ground of the main unit housing. The fixing ground terminal may be connected to the ground of the main unit housing via the main unit ground terminal when the fixing connector is attached to the main unit connector.

[0008] The fixing ground terminal is connected to the ground of the main unit enclosure via the main unit ground terminal when the fixing connector is attached to the main unit connector. After the fixing connector and the main unit connector are connected, the relay board can be connected to the ground of the main unit enclosure via the connector.

[0009] The fixing connector may have multiple terminals, including a fixing ground terminal. The fixing ground terminal may protrude further downstream than the other terminals in the direction in which the fixing connector is connected to the main connector.

[0010] The fixing ground terminal protrudes further downstream than the other terminals in the connection direction of the fixing connector to the main unit connector. This allows static electricity to be discharged from the fixing ground terminal to the connection frame when static electricity discharge occurs between the fixing connector and the main unit connector when the fixing device is mounted to the main unit housing. This helps to suppress failure of the temperature sensor.

[0011] The fixing device may also include a compression coil spring. The compression coil spring provides electrical conductivity between the ground of the relay board and the connecting frame. The compression coil spring is positioned between the relay board and the connecting frame.

[0012] By placing a compression coil spring between the relay board and the connecting frame to connect the ground of the relay board and the connecting frame, the conductivity between the ground of the relay board and the connecting frame can be stabilized.

[0013] The fixing device further comprises a resin frame and screws, and the intermediate substrate may be long in the longitudinal direction. The resin frame is positioned between the relay board and the connecting frame. The screws secure the relay board to the resin frame. The resin frame has claws that engage with one end of the relay substrate in the longitudinal direction. The screws secure the other end of the relay board to the resin frame in the longitudinal direction.

[0014] The resin frame has claws that engage with one end of the intermediate board in the longitudinal direction, and screws that secure the other end of the intermediate board to the resin frame in the longitudinal direction, allowing the intermediate board to be easily fixed to the resin frame.

[0015] The compression coil spring may be positioned between the claw and the screw in the longitudinal direction. In the longitudinal direction, the distance from the screw to the compression coil spring may be smaller than the distance from the compression coil spring to the center of the relay board.

[0016] In the longitudinal direction, when the compression coil spring is positioned between the claw and the screw and the distance from the screw to the compression coil spring is smaller than the distance from the compression coil spring to the center of the relay board, when fixing the relay board to the resin frame with the screw, the deflection of the relay board can be suppressed while the compression coil spring can be compressed.

[0017] The compression coil spring may have a coil and an arm extending from an end of the coil close to the relay board. The arm may engage with the resin frame to restrict the rotation of the compression coil spring.

[0018] By engaging the arm of the compression coil spring with the resin frame to restrict the rotation of the compression coil spring, the conduction between the ground of the relay board and the compression coil spring can be stabilized.

[0019] The fixing device may further include a contact portion. The contact portion contacts the main body housing and conducts with the ground of the main body housing when the fixing device is mounted on the main body housing. The contact portion conducts with the connection frame.

[0020] The contact portion that contacts the main body housing and conducts with the ground of the main body housing when the fixing device is mounted on the main body housing conducts with the connection frame, so that the connection frame and the ground of the main body housing can be conducted through the contact portion.

[0021] The contact portion may be a boss extending in the longitudinal direction.

[0022] Since the contact portion is a boss extending in the longitudinal direction, it is easy to contact the fixing device and the main body housing.

[0023] The first side frame may be made of metal, and the boss may be fixed to the first side frame.

[0024] The boss is fixed to the first metal side frame, allowing electrical conductivity between the connecting frame, the first side frame, and the ground of the relay board and the main casing via the boss.

[0025] The contact portion may contact the main housing and establish electrical contact with the ground of the main housing when the fixing device is mounted to the main housing, before the fixing connector is connected to the main housing connector.

[0026] The contact portion makes contact with the main body housing before the fuser connector is connected to the main body connector. This allows static electricity to be more reliably discharged through the connecting frame if static electricity discharge occurs between the fuser connector and the main body connector when the fuser device is mounted to the main body housing. This helps to further suppress failure of the temperature sensor. [Effects of the Invention]

[0027] This can help prevent temperature sensor failures. [Brief explanation of the drawing]

[0028] [Figure 1] This is a cross-sectional view showing an image forming apparatus. [Figure 2] This is a perspective view showing the fixing device and the main body housing with the rear cover open. [Figure 3] This is a perspective view showing the fuser connector side of the fuser device. [Figure 4] This diagram shows the fixing device, the guide surface of the main housing, the first recess, and the second recess. [Figure 5] This is a perspective view showing the first side frame, second side frame, connecting frame, first temperature sensor, second temperature sensor, and relay board of the fixing device. [Figure 6] This is a circuit diagram showing the electrical connection between the fixing device and the main housing. [Figure 7]This is a perspective view showing the resin frame and screws of the fixing device. [Figure 8] This is a perspective view showing the resin frame, intermediate circuit board, screws, and compression coil spring. [Figure 9] This is a view of the relay board and compression coil spring from a second direction. [Figure 10] This is a cross-sectional view of XX in Figure 9. [Figure 11] Figure (a) is a perspective view showing a compression coil spring, and Figure 9 is shown in an enlarged view (b). [Figure 12] Figures (a) and (b) show the fixing connector and the main body connector. [Figure 13] Figures (a) and (b) illustrate the installation of the fixing device. [Figure 14] Figures (a) and (b), following Figure 13, illustrate the installation of the fixing device. [Modes for carrying out the invention]

[0029] Next, embodiments will be described. As shown in Figure 1, the image forming apparatus 1 comprises a main body housing 10, a sheet supply unit 20, an image forming unit 30, a fixing device 80, and a sheet discharge unit 90.

[0030] The main casing 10 includes a front cover 11, an output tray 12, and a rear cover 13. The front cover 11 opens and closes the opening on the front side of the main casing 10. The rear cover 13 opens and closes the opening on the rear side of the main casing 10.

[0031] The sheet supply unit 20 comprises a sheet tray 21 and a supply mechanism 22. The sheet tray 21 holds sheets S such as paper. The supply mechanism 22 supplies the sheets S in the sheet tray 21 to the image forming unit 30.

[0032] The image forming unit 30 comprises an exposure apparatus 40, a process unit PU, and a transfer unit 70.

[0033] The exposure apparatus 40 is located above the process unit PU. The exposure apparatus 40 emits a light beam as shown by the dashed line to expose the surface of the photosensitive drum 51.

[0034] The process unit PU is located between the sheet tray 21 and the exposure device 40. The process unit PU is detachable from the main housing 10 through an opening in the main housing 10, which is opened by opening the front cover 11. The process unit PU comprises a drum cartridge 50 and multiple toner cartridges 60.

[0035] The drum cartridge 50 comprises a plurality of photosensitive drums 51, a plurality of chargers 52 corresponding to the plurality of photosensitive drums 51, and a drum frame 53. The drum frame 53 supports the photosensitive drums 51 and the chargers 52. The drum frame 53 is movably supported in the main body housing 10. A toner cartridge 60 can be attached to and removed from the drum frame 53.

[0036] Multiple toner cartridges 60 each contain toner of a different color. Each toner cartridge 60 includes a developer roller 61, a supply roller 62, a layer thickness regulating blade 63, a toner storage section 64 for storing toner, and an agitator 65. The agitator 65 agitates the toner in the toner storage section 64. The agitator 65 supplies toner to the supply roller 62. The supply roller 62 supplies toner to the developer roller 61. The layer thickness regulating blade 63 regulates the toner on the developer roller 61 to a constant thickness.

[0037] The transfer unit 70 is located between the sheet tray 21 and the process unit PU. The transfer unit 70 comprises a drive roller 71, a driven roller 72, a conveyor belt 73, and a plurality of transfer rollers 74. The conveyor belt 73 is an endless belt for conveying the sheet S. The drive roller 71 and the driven roller 72 rotate the conveyor belt 73. The transfer rollers 74 are located inside the conveyor belt 73. The transfer rollers 74 sandwich the conveyor belt 73 between themselves and the photosensitive drum 51.

[0038] The fixing device 80 comprises a heating element 81 and a pressure roller 82 as a pressurizing element. The heating element 81 has a heating roller 81R and a heater 81A. The heating roller 81R heats the sheet S. The heater 81A is located inside the heating roller 81R. The heating roller 81R rotates under the driving force of a drive source (not shown). The pressure roller 82 nips the sheet S between itself and the heating element 81. The pressure roller 82 rotates in conjunction with the heating roller 81R.

[0039] The charger 52 charges the surface of the photosensitive drum 51. The exposure device 40 exposes the charged surface of the photosensitive drum 51 with a light beam. This forms an electrostatic latent image on the photosensitive drum 51. The developing roller 61 supplies toner to the photosensitive drum 51 on which the electrostatic latent image has been formed. This forms a toner image on the photosensitive drum 51.

[0040] The photosensitive drum 51 and the transfer roller 74 transport the sheet S supplied from the sheet supply unit 20, thereby transferring the toner image formed on the photosensitive drum 51 to the sheet S. The fixing device 80 transports the sheet S, on which the toner image has been transferred, using the heating roller 81R and the pressure roller 82, thereby fixing the toner image to the sheet S.

[0041] The sheet discharge unit 90 has a conveyor roller 91 and a discharge roller 92. The conveyor roller 91 conveys the sheet S to the discharge roller 92. The discharge roller 92 discharges the sheet S onto the discharge tray 12.

[0042] As shown in Figure 2, the fixing device 80 can be mounted on the main body housing 10 of the image forming apparatus 1. More specifically, the fixing device 80 can be mounted on the main body housing 10 through the opening 10B of the main body housing 10, which is opened by opening the rear cover 13. In the following description, directions will be described using the longitudinal direction, the first direction, and the second direction shown in Figure 2.

[0043] The longitudinal direction is the longitudinal direction of the heating element 81. The heating element 81 and the pressure roller 82 each extend in the longitudinal direction. In this embodiment, the longitudinal direction is the direction along the left-right direction of the image forming apparatus 1. One side of the longitudinal direction corresponds to the right side of the image forming apparatus 1, and the other side of the longitudinal direction corresponds to the left side of the image forming apparatus 1.

[0044] The first direction is the direction in which the fixing device 80 is mounted to the main housing 10. The first direction is the direction intersecting the longitudinal direction. In the embodiment, the first direction is the direction perpendicular to the longitudinal direction. The first direction is the direction along the front-to-back direction of the image forming apparatus 1. One end of the first direction corresponds to the rear side of the image forming apparatus 1, and the other end of the first direction corresponds to the front side of the image forming apparatus 1. The fixing device 80 can be mounted to the main housing 10 from one end of the first direction to the other.

[0045] The second direction is a direction that intersects both the longitudinal direction and the first direction. In the embodiment, the second direction is a direction that is perpendicular to both the longitudinal direction and the first direction. The second direction is a direction along the vertical direction of the image forming apparatus 1. One side of the second direction corresponds to the lower side of the image forming apparatus 1, and the other side of the second direction corresponds to the upper side of the image forming apparatus 1. The arrows indicating directions in the drawing point to one side of each direction.

[0046] As shown in Figures 2 and 3, the fixing device 80 further comprises a pair of first bosses 120 as contact parts, a pair of second bosses 130, a protrusion 140, and a fixing connector 150. The image forming apparatus 1 further comprises a main body connector 160.

[0047] The first boss 120 is a portion that is positioned in a first and second direction relative to the main housing 10 by contacting the main housing 10 when the fixing device 80 is mounted on the main housing 10. The first boss 120 has a cylindrical shape. The first boss 120 extends in the longitudinal direction. The first boss 120 is located at one end and the other end of the fixing device 80 in the longitudinal direction. The pair of first bosses 120 have a symmetrical structure with respect to a plane perpendicular to the longitudinal direction. The first boss 120 as a contact portion is an example of a "boss".

[0048] The second boss 130 is a part that stops the rotation of the fixing device 80 around the first boss 120 by contacting the main housing 10 when the fixing device 80 is mounted on the main housing 10. The second boss 130 has a cylindrical shape. The second boss 130 is located to one side of the first boss 120 in the first direction. The second boss 130 is located to one side of the first boss 120 in the second direction. The second boss 130 extends in the longitudinal direction. The second boss 130 is located at one end and the other end of the fixing device 80 in the longitudinal direction. The pair of second bosses 130 have a symmetrical structure with respect to a plane perpendicular to the longitudinal direction.

[0049] The protrusion 140 is located at the other end of the fixing device 80 in the first direction. The protrusion 140 is located at the other end of the fixing device 80 in the longitudinal direction and protrudes toward the other side in the first direction. The shape of the cross section of the protrusion 140 perpendicular to the first direction is cross-shaped. The other end of the protrusion 140 in the first direction is thinner than one end in the first direction.

[0050] The fixing connector 150 is a connector that can be connected to the main body connector 160 of the main body housing 10. The fixing connector 150 is connected to the main body connector 160 when the fixing device 80 is mounted on the main body housing 10. The fixing connector 150 is located at one end of the fixing device 80 in the longitudinal direction. The main body connector 160 is a floating connector held by the main body housing 10 so as to be movable relative to the main body housing 10. When the main body connector 160 and the fixing connector 150 are connected, power can be supplied to, for example, the heater 81A of the heating element 81.

[0051] As shown in Figure 4, the main housing 10 has a guide surface 310, a first recess 320, and a second recess 330 on both sides of the fixing device 80 in the longitudinal direction (see also Figure 13(a)). The guide surface 310, the first recess 320, and the second recess 330 have a symmetrical structure with respect to a plane perpendicular to the longitudinal direction.

[0052] The first recess 320 is a recess that is recessed toward one of the second directions. The first boss 120 of the fixing device 80 is located within the first recess 320 when the fixing device 80 is mounted on the main housing 10. The main housing 10 has metal plates 300 on both sides of the fixing device 80 in the longitudinal direction. The first recess 320 is formed in the metal plate 300. The metal plate 300 is connected to the ground of the main housing 10.

[0053] The first boss 120 is made of metal. More specifically, the first boss 120 consists of a metal rod. The first boss 120 contacts the metal plate 300 of the main housing 10 when the fixing device 80 is mounted on the main housing 10, and is electrically connected to the ground of the main housing 10. In this embodiment, when the fixing device 80 is mounted on the main housing 10, the first boss 120 contacts the metal plate 300 of the main housing 10 before the fixing connector 150 is connected to the main connector 160, and is electrically connected to the ground of the main housing 10.

[0054] The guide surface 310 is a surface that guides the first boss 120 toward the first recess 320 when the fixing device 80 is attached to the main housing 10. The guide surface 310 has a first guide surface 311, a second guide surface 312, and a third guide surface 313. The first guide surface 311 extends in the first direction.

[0055] The second guide surface 312 and the third guide surface 313 are formed on the metal plate 300. The second guide surface 312 is located between the first guide surface 311 and the first recess 320. More specifically, the second guide surface 312 is located between the first guide surface 311 and the third guide surface 313. The second guide surface 312 is inclined diagonally upward so that it is located on the other side of the second direction as one side moves from one side of the first direction to the other side.

[0056] The third guide surface 313 is located between the second guide surface 312 and the first recess 320. The third guide surface 313 extends in the first direction from one end of the second guide surface 312 toward the other.

[0057] The second recess 330 is a recess that curves inward toward the other direction in the first direction. The second boss 130 fits into the second recess 330 when the fixing device 80 is mounted on the main housing 10.

[0058] The main housing 10 has an elongated hole 340. The elongated hole 340 is a bottomed hole that is elongated in the second direction. The elongated hole 340 has a shape that is recessed toward the other side in the first direction. The protruding portion 140 of the fixing device 80 enters the elongated hole 340 when the fixing device 80 is mounted on the main housing 10. The fixing device 80 is positioned in the longitudinal direction by the protruding portion 140 entering the elongated hole 340.

[0059] The longitudinal dimension of the elongated hole 340 is approximately the same as the longitudinal dimension of the projection 140. The projection 140 fits into the elongated hole 340 in the longitudinal direction. The elongated hole 340 restricts the longitudinal movement of the projection 140. As a result, the elongated hole 340 restricts the longitudinal movement of the fixing device 80. The second dimension of the elongated hole 340 is larger than the second dimension of the projection 140.

[0060] As shown in Figure 5, the fixing device 80 further comprises a first side frame 210, a second side frame 220, a connecting frame 230, a first temperature sensor S1, a second temperature sensor S2, a sheet sensor S3, a cam sensor S4, and a relay board 240.

[0061] The first side frame 210, the second side frame 220, and the connecting frame 230 are metal frames. More specifically, the first side frame 210, the second side frame 220, and the connecting frame 230 are made of metal plates.

[0062] The first side frame 210 is positioned on one side of the heating member 81 in the longitudinal direction. The first side frame 210 holds one end of the heating roller 81R in the longitudinal direction. One of the first bosses 120 in the longitudinal direction is fixed to the first side frame 210. In this embodiment, one of the first bosses 120 in the longitudinal direction is fixed to the first side frame 210 by crimping.

[0063] The second side frame 220 is positioned on the other side of the heating member 81 in the longitudinal direction. The second side frame 220 holds the other end of the heating roller 81R in the longitudinal direction. The other first boss 120 in the longitudinal direction is fixed to the second side frame 220. In this embodiment, the other first boss 120 in the longitudinal direction is fixed to the second side frame 220 by crimping.

[0064] The connecting frame 230 connects the first side frame 210 and the second side frame 220. The connecting frame 230 extends in the longitudinal direction. In the longitudinal direction, one end of the connecting frame 230 is fixed to the first side frame 210 by a screw SC1. In the longitudinal direction, the other end of the connecting frame 230 is fixed to the second side frame 220 by a screw SC2.

[0065] The first boss 120 is electrically connected to the connecting frame 230 via the first side frame 210 or the second side frame 220. With the fixing device 80 mounted on the main housing 10, the connecting frame 230 is connected to the ground of the main housing 10 via the first side frame 210 or the second side frame 220, the first boss 120, and the metal plate 300 of the main housing 10 (see Figure 4).

[0066] The first temperature sensor S1 and the second temperature sensor S2 are sensors that detect the temperature of the heating element 81. More specifically, the first temperature sensor S1 and the second temperature sensor S2 are sensors that detect the temperature of the heating roller 81R.

[0067] The first temperature sensor S1 is, for example, a non-contact type thermistor. The first temperature sensor S1 is fixed to the connecting frame 230 by a screw SC3. The first temperature sensor S1 is positioned with a gap between it and the surface of the heating roller 81R. The first temperature sensor S1 is positioned facing the vicinity of the center of the heating roller 81R in the longitudinal direction.

[0068] The second temperature sensor S2 is, for example, a contact-type thermistor. The second temperature sensor S2 is fixed to the connecting frame 230 by a screw SC4. The second temperature sensor S2 is positioned in contact with the surface of the heating roller 81R. The second temperature sensor S2 is positioned differently from the first temperature sensor S1 in the longitudinal direction. Specifically, the second temperature sensor S2 is positioned facing the other end of the heating roller 81R in the longitudinal direction.

[0069] The sheet sensor S3 is a sensor that detects the presence or absence of a sheet S between the heating roller 81R and the pressure roller 82. As an example, the sheet sensor S3 includes an actuator that oscillates when a sheet S passing between the heating roller 81R and the pressure roller 82 comes into contact with it, and an optical sensor that detects the oscillation of the actuator.

[0070] The cam sensor S4 is a sensor that detects the phase of the cam 85. The fixing device 80 includes the cam 85 and the cam gear 86. The cam 85 changes the nip pressure between the heating roller 81R and the pressure roller 82 by rotating. The cam gear 86 is a gear that rotates the cam 85 and rotates by receiving a driving force from a drive source (not shown). The cam sensor S4 is, for example, an optical sensor. The cam sensor S4 detects the phase of the cam 85 by detecting the phase of the cam gear 86. In the image forming apparatus 1, the nip pressure between the heating roller 81R and the pressure roller 82 can be determined by the cam sensor S4 detecting the phase of the cam 85.

[0071] The relay board 240 is a circuit board that is long in the longitudinal direction. The relay board 240 relays the signal from the first temperature sensor S1 to the fixing connector 150, and also relays the signal from the second temperature sensor S2 to the fixing connector 150. In addition, the relay board 240 relays the signal from the sheet sensor S3 to the fixing connector 150, and also relays the signal from the cam sensor S4 to the fixing connector 150.

[0072] The relay board 240 includes a first temperature sensor connector CN1, a second temperature sensor connector CN2, a sheet sensor connector CN3, a cam sensor connector CN4, and a relay connector CN5. The relay board 240 is connected to the first temperature sensor S1 by connecting a first cable C1 extending from the first temperature sensor S1 to the first temperature sensor connector CN1.

[0073] The relay board 240 is connected to the second temperature sensor S2 by connecting the second cable C2 extending from the second temperature sensor S2 to the second temperature sensor connector CN2. The relay board 240 is connected to the sheet sensor S3 by connecting the third cable C3 extending from the sheet sensor S3 to the sheet sensor connector CN3.

[0074] The relay board 240 is connected to the cam sensor S4 by the fourth cable C4 extending from the cam sensor S4 being connected to the cam sensor connector CN4. The relay board 240 is connected to the fuser connector 150 by the fifth cable C5 extending from the fuser connector 150 being connected to the relay connector CN5.

[0075] As shown in Figure 6, the image forming apparatus 1 further comprises a main board 170 and a low-voltage power supply board 180. The main board 170 and the low-voltage power supply board 180 are located inside the main body housing 10.

[0076] The main board 170 controls the fixing device 80. The main board 170 has an ASIC 171 and a plurality of DC / DC converters 172 to 174. DC / DC converter 172 converts the DC voltage (24V) supplied from the low-voltage power supply board 180 to a predetermined DC voltage (5.3V) and outputs it. DC / DC converter 173 converts the DC voltage (5.3V) supplied from DC / DC converter 172 to a predetermined DC voltage (3.3V) and outputs it. DC / DC converter 174 converts the DC voltage (5.3V) supplied from DC / DC converter 172 to a predetermined DC voltage (1.8V) and outputs it.

[0077] The low-voltage power supply board 180 outputs power to the fuser 80 and the main board 170. The low-voltage power supply board 180 includes an AC / DC converter 181, a relay 182, and a switching circuit 183. The AC / DC converter 181 converts the AC voltage supplied from the power supply to a predetermined DC voltage (24V) and outputs it. The main board 170 controls the heater 81A of the fuser 80 by outputting control signals to control the relay 182 and the switching circuit 183.

[0078] The first temperature sensor S1, the sheet sensor S3, and the cam sensor S4 are supplied with power (3.3V) from the main board 170 via connectors 150, 160 and the relay board 240. The second temperature sensor S2 is supplied with power (1.8V) from the main board 170 via connectors 150, 160 and the relay board 240.

[0079] The signals SG1 from the first temperature sensor S1, SG2 from the second temperature sensor S2, SG3 from the sheet sensor S3, and SG4 from the cam sensor S4 are output to the main board 170 via the relay board 240 and connectors 150 and 160. The sheet sensor S3 and cam sensor S4 are connected to the ground of the main board 170 via the relay board 240 and connectors 150 and 160. The ground of the main board 170 is earthed via the low-voltage power supply board 180.

[0080] The ground of the relay board 240 is electrically connected to the metal plate 300 of the main body housing 10 via the compression coil spring 270 (described later), the connecting frame 230, the first side frame 210 or the second side frame 220, and the first boss 120. The metal plate 300 is connected to the main body frame ground FG. The main body frame ground FG is made of a metal plate. The main body frame ground FG is grounded via the low-voltage power supply board 180.

[0081] As shown in Figure 7, the fixing device 80 further comprises a resin frame 250 and screws 260. The resin frame 250 is a resin frame that covers the connecting frame 230. The resin frame 250 is positioned between the relay board 240 and the connecting frame 230. The relay board 240 is fixed to the resin frame 250.

[0082] As shown in Figure 8, the resin frame 250 has a first base 251, a second base 252, a claw 253, a first hole 254, and a second hole 255.

[0083] The first base 251 is a trapezoidal portion that supports one end of the relay substrate 240 in the longitudinal direction. The first base 251 protrudes toward the other end in the second direction. The second base 252 is a trapezoidal portion that supports the other end of the relay substrate 240 in the longitudinal direction. The second base 252 protrudes toward the other in the second direction.

[0084] The claw 253 is a claw that engages with one end of the relay substrate 240 in the longitudinal direction. The claw 253 extends beyond the first base 251 to the other end in the second direction, with its tip protruding toward the other end in the longitudinal direction. The first hole 254 is a hole into which a screw 260 is fastened. The first hole 254 has a shape that is recessed toward one of the second directions. The first hole 254 is located on the second base 252.

[0085] The second hole 255 is a hole in which the compression coil spring 270 is positioned. The second hole 255 penetrates in the second direction. The second hole 255 is located on the second base 252. The first hole 254 and the second hole 255 are aligned in the longitudinal direction. The second hole 255 is located between the claw 253 and the first hole 254 in the longitudinal direction.

[0086] Screw 260 is used to fix the intermediate board 240 to the resin frame 250. More specifically, the intermediate board 240 has a through hole 241 at its other end in the longitudinal direction. The through hole 241 penetrates in a second direction. Screw 260 is fastened through the through hole 241 of the intermediate board 240 to the first hole 254 of the resin frame 250. In this way, screw 260 fixes the other end of the intermediate board 240 to the resin frame 250 in the longitudinal direction.

[0087] The ground of the relay board 240 is electrically connected to the connecting frame 230. More specifically, as shown in Figure 9, the relay board 240 has a board ground terminal 242, indicated by a thin dashed line, on one side in the second direction. The fixing device 80 further includes a compression coil spring 270. The relay board 240 is electrically connected to the connecting frame 230 via the board ground terminal 242 and the compression coil spring 270.

[0088] As shown in Figure 10, the compression coil spring 270 is a metal spring that provides electrical conductivity between the ground of the relay board 240 and the connecting frame 230. The compression coil spring 270 is positioned between the relay board 240 and the connecting frame 230 in a compressed state. In the second direction, one end of the compression coil spring 270 is in contact with the connecting frame 230. In the second direction, the other end of the compression coil spring 270 is in contact with the board ground terminal 242 of the relay board 240.

[0089] The compression coil spring 270 is located longitudinally between the claw 253 of the resin frame 250 and the screw 260. In the longitudinal direction, the distance D1 from the screw 260 to the compression coil spring 270 is smaller than the distance D2 from the compression coil spring 270 to the center 240C of the intermediate board 240. In other words, in the longitudinal direction, the compression coil spring 270 is closer to the screw 260 than to the center 240C of the intermediate board 240.

[0090] As shown in Figure 11(a), the compression coil spring 270 has a coil 271 and an arm 272. The arm 272 extends from the other end of the coil 271 in the second direction. In other words, the arm 272 extends from the end of the coil 271 closer to the relay substrate 240.

[0091] The arm 272 has a first portion 272A and a second portion 272B. The first portion 272A extends radially outward from the other end of the coil 271 in a second direction. The second portion 272B extends radially outward from the outer end of the first portion 272A in the coil 271 in one direction of the second direction.

[0092] As shown in Figure 11(b), the compression coil spring 270 has an arm 272 that is in contact with the board ground terminal 242 of the relay board 240. More specifically, the first part 272A of the arm 272 of the compression coil spring 270 is in contact with the main terminal 242A of the board ground terminal 242, which will be described later.

[0093] The arm 272 engages with the resin frame 250 to restrict the rotation of the compression coil spring 270. More specifically, the resin frame 250 has an engagement surface 256 on one side in a first direction. The arm 272 has a second portion 272B that can contact the engagement surface 256 from one side in the first direction. The arm 272 restricts the rotation of the compression coil spring 270 around the coil 271 by the contact of the second portion 272B with the engagement surface 256 of the resin frame 250.

[0094] The board ground terminal 242 has a main terminal 242A and a sub-terminal 242B. The main terminal 242A is located at one end of the board ground terminal 242 in the first direction and extends in the longitudinal direction. The sub-terminal 242B is located to the other side of the main terminal 242A in the first direction and extends obliquely to the longitudinal direction.

[0095] In this embodiment, the compression coil spring 270 is rotatable between a first contact position, indicated by a solid line on the arm 272, and a second contact position, indicated by a dashed line on the arm 272. The longitudinal length of the main terminal 242A is such that it contacts the first portion 272A of the arm 272 when the compression coil spring 270 is in the first contact position, and also contacts the first portion 272A of the arm 272 when the compression coil spring 270 is in the second contact position.

[0096] Sub-terminal 242B can make contact with coil 271 of compression coil spring 270. Even if arm 272 of compression coil spring 270 loses contact with main terminal 242A for any reason, coil 271 can make contact with sub-terminal 242B, thereby enabling conductivity between the ground of the relay board 240 and the connecting frame 230.

[0097] The ground of the relay board 240 is connected to the ground of the main body housing 10 via the compression coil spring 270, the connecting frame 230, the first side frame 210 or the second side frame 220, the first boss 120, and the metal plate 300, with the first boss 120 in contact with the metal plate 300 (see Figure 4) of the main body housing 10.

[0098] As shown in Figures 12(a) and (b), the main connector 160 has a plurality of terminals 161 and a main connector housing 162 that holds the plurality of terminals 161. The fixing connector 150 has a plurality of terminals 151 corresponding to the terminals 161 of the main connector 160 and a fixing connector housing 152 that holds the plurality of terminals 151. The terminals 151 of the fixing connector 150 and the terminals 161 of the main connector 160 are connected by the mating of the fixing connector housing 152 and the main connector housing 162.

[0099] The multiple terminals 151 of the fixing connector 150 include, for example, terminals that output signals from the first temperature sensor S1 and terminals that output signals from the second temperature sensor S2. The multiple terminals 161 of the main unit connector 160 include, for example, terminals that receive signals from the first temperature sensor S1 and terminals that receive signals from the second temperature sensor S2.

[0100] Furthermore, multiple terminals 161 of the main connector 160 include the main ground terminal 161A, and multiple terminals 151 of the fixing connector 150 include the fixing ground terminal 151A. The main ground terminal 161A is connected to the ground of the main enclosure 10. The fixing ground terminal 151A is connected to the ground of the relay board 240.

[0101] The fixing ground terminal 151A is connected to the main unit ground terminal 161A when the fixing connector 150 is attached to the main unit connector 160. As a result, the fixing ground terminal 151A is connected to the ground of the main unit housing 10 via the main unit ground terminal 161A when the fixing connector 150 is attached to the main unit connector 160.

[0102] The fixing ground terminal 151A protrudes further downstream than the other terminals 151 in the connection direction. The connection direction is the direction in which the fixing connector 150 is connected to the main connector 160. In this embodiment, the fixing ground terminal 151A is longer in the connection direction than the other terminals 151 and extends further downstream in the connection direction than the other terminals 151. As a result, when the fixing connector 150 is attached to the main connector 160, the fixing ground terminal 151A approaches the main ground terminal 161A first and connects to the main ground terminal 161A first.

[0103] As shown in Figure 13(a), the main connector 160 further includes a first guide pin 163 and a second guide pin 164. The main connector housing 162 is located between the first guide pin 163 and the second guide pin 164 in a second direction. The first guide pin 163 and the second guide pin 164 extend in a first direction. The tips of the first guide pin 163 and the second guide pin 164 are located in one direction relative to the main connector housing 162 in the first direction.

[0104] The fixing device 80 has a first guide hole 153 and a second guide hole 154. The fixing connector housing 152 is located between the first guide hole 153 and the second guide hole 154 in the second direction. The first guide hole 153 is a hole for receiving the first guide pin 163. The second guide hole 154 is a hole for receiving the second guide pin 164. The fixing connector housing 152, the first guide hole 153 and the second guide hole 154 are open toward the other in the first direction.

[0105] Next, we will explain the connection between the relay board 240 and the ground of the main body housing 10 when the fixing device 80 is mounted on the main body housing 10. As shown in Figure 13(a), when the fixing device 80 is inserted into the main body housing 10, the first boss 120 of the fixing device 80 comes into contact with the first guide surface 311 of the main body housing 10 and is guided by the first guide surface 311.

[0106] As shown in Figure 13(b), as the fixing device 80 is further inserted, the first guide hole 153 of the fixing device 80 receives the first guide pin 163 of the main body connector 160, and the second guide hole 154 receives the second guide pin 164. In addition, the first boss 120 contacts the second guide surface 312 formed on the metal plate 300 of the main body housing 10. As a result, the relay board 240, which is electrically connected to the first boss 120, is connected to the ground of the main body housing 10 via the metal plate 300 before the fixing connector 150 is connected to the main body connector 160.

[0107] As shown in Figure 14(a), as the fixing device 80 is further inserted, the first boss 120 is guided by the second guide surface 312 and then by the third guide surface 313 in a direction along the first direction. Also, the fixing connector housing 152 of the fixing connector 150 fits into the main connector housing 162 of the main connector 160, and the terminal 151 of the fixing connector 150 (not shown) and the terminal 161 of the main connector 160 come into contact.

[0108] As the fixing device 80 is further inserted and the first boss 120 disengages from the third guide surface 313, the first boss 120 enters the first recess 320, as shown in Figure 14(b). As a result, the fixing device 80 is mounted on the main housing 10 and positioned relative to the main housing 10 in the first and second directions.

[0109] Furthermore, the fixing connector housing 152 is mated into the main unit connector housing 162, and the fixing connector 150 is connected to the main unit connector 160. As a result, the fixing ground terminal 151A and the main unit ground terminal 161A are connected (see Figure 12(a)), and the relay board 240 is also connected to the ground of the main unit housing 10 via connectors 150 and 160.

[0110] Next, the effects of the embodiment will be described. The ground of the relay board 240 is electrically connected to the connection frame 230, which is connected to the ground of the main body housing 10. This allows static electricity to be discharged through the connection frame 230 when static electricity discharge occurs between the fixing connector 150 and the main body connector 160 when the fixing device 80 is mounted on the main body housing 10. This helps to suppress failure of the temperature sensors S1 and S2.

[0111] The fixing ground terminal 151A is connected to the ground of the main unit housing 10 via the main unit ground terminal 161A when the fixing connector 150 is attached to the main unit connector 160. After the fixing connector 150 and the main unit connector 160 are connected, the relay board 240 can be connected to the ground of the main unit housing 10 via connectors 150 and 160.

[0112] The fixing ground terminal 151A protrudes downstream of the other terminals 151 in the connection direction of the fixing connector 150 to the main unit connector 160. This allows static electricity to be discharged from the fixing ground terminal 151A to the connection frame 230 when static electricity discharge occurs between the fixing connector 150 and the main unit connector 160 when the fixing device 80 is mounted to the main unit housing 10. This helps to suppress failure of the temperature sensors S1 and S2.

[0113] By placing the compression coil spring 270, which connects the ground of the relay board 240 to the connecting frame 230, between the relay board 240 and the connecting frame 230, the conductivity between the ground of the relay board 240 and the connecting frame 230 can be stabilized.

[0114] The resin frame 250 has a claw 253 that engages with one end of the intermediate board 240 in the longitudinal direction, and the screw 260 fixes the other end of the intermediate board 240 to the resin frame 250 in the longitudinal direction. This makes it easier to fix the intermediate board 240 to the resin frame 250 compared to, for example, fixing both ends of the intermediate board 240 to the resin frame 250 with screws in the longitudinal direction.

[0115] In the longitudinal direction, the compression coil spring 270 is positioned between the claw 253 and the screw 260, and the distance D1 from the screw 260 to the compression coil spring 270 is smaller than the distance D2 from the compression coil spring 270 to the center 240C of the intermediate board 240. This allows the compression coil spring 270 to be compressed while suppressing the deflection of the intermediate board 240 when the intermediate board 240 is fixed to the resin frame 250 with the screw 260.

[0116] The arm 272 of the compression coil spring 270 engages with the resin frame 250, restricting the rotation of the compression coil spring 270, thereby stabilizing the electrical connection between the ground of the relay board 240 and the compression coil spring 270.

[0117] With the fixing device 80 mounted on the main housing 10, the first boss 120, which contacts the main housing 10 and is electrically connected to the ground of the main housing 10, is electrically connected to the connecting frame 230, thereby enabling electrical connection between the connecting frame 230 and the ground of the main housing 10 via the first boss 120.

[0118] The first boss 120, which serves as the contact point, is a boss that extends in the longitudinal direction, making it easy to bring the fixing device 80 into contact with the main housing 10.

[0119] The first boss 120 is fixed to the metal first side frame 210 or second side frame 220, which allows electrical connection between the relay board 240 and the ground of the main body housing 10 via the connecting frame 230, the first side frame 210 or second side frame 220, and the first boss 120.

[0120] The first boss 120 contacts the main body housing 10 before the fuser connector 150 is connected to the main body connector 160. This allows static electricity to be more reliably discharged through the connecting frame 230 when static electricity discharge occurs between the fuser connector 150 and the main body connector 160 when the fuser device 80 is mounted on the main body housing 10. This further reduces the risk of failure of the temperature sensors S1 and S2.

[0121] The embodiments have been described above, but the fixing device can be modified as appropriate as shown in the following examples.

[0122] In the embodiment, the contact portion was a pair of first bosses 120, but the contact portion may be one of the first bosses 120 (one boss). Furthermore, in the embodiment, the relay board 240 and the ground of the main housing 10 were electrically connected via the first side frame 210 and the second side frame 220 to which the first bosses 120 were fixed. However, for example, the relay board and the ground of the main housing may be electrically connected via one boss and the first side frame without going through the second side frame, or via one boss and the second side frame without going through the first side frame.

[0123] In this embodiment, the contact portion was the first boss 120 (boss), but for example, the contact portion may be at least one edge of the first side frame and the second side frame. To add to this, at least one edge of the first side frame and the second side frame may contact the main body housing and be electrically connected to the ground of the main body housing when the fixing device is mounted on the main body housing.

[0124] In this embodiment, the connecting frame 230 was connected to the ground of the main housing 10 via the side frames 210 and 220 and the first boss 120. However, for example, the connecting frame itself may be connected to the ground of the main housing by contacting the main housing while the fixing device is mounted on the main housing.

[0125] In this embodiment, the intermediate substrate 240 was fixed to the resin frame 250 by a screw 260 at one end in the longitudinal direction and by a claw 253 of the resin frame 250 at the other end in the longitudinal direction. However, for example, the intermediate substrate may be fixed to the resin frame at both ends in the longitudinal direction by screws, or at both ends in the longitudinal direction by claws of the resin frame.

[0126] In the embodiment, the compression coil spring 270 had an arm 272, which engaged with the resin frame 250 to restrict the rotation of the compression coil spring 270. However, for example, if the coil of the compression coil spring is in contact with the ground terminal of the relay board, the compression coil spring does not need to have an arm to restrict its rotation.

[0127] In this embodiment, the fixing device 80 was equipped with a compression coil spring 270 that provided electrical conductivity between the ground of the relay board 240 and the connecting frame 230. However, for example, the fixing device may be equipped with a spring other than the compression coil spring that provides electrical conductivity between the ground of the relay board and the connecting frame. Also, for example, the fixing device may not be equipped with a spring that provides electrical conductivity between the ground of the relay board and the connecting frame. Furthermore, if no spring is provided for conductivity, for example, the relay board and the connecting frame may be in direct contact, and the ground of the relay board may be electrically conductive with the connecting frame.

[0128] In this embodiment, the fixing ground terminal 151A protruded further downstream than the other terminals 151 in the connection direction of the fixing connector 150. However, for example, the position of the downstream end of the fixing ground terminal in the connection direction of the fixing connector may be the same as the position of the downstream end of the other terminals.

[0129] In this embodiment, the first temperature sensor S1 was a non-contact type thermistor, but for example, the first temperature sensor may be a contact type thermistor. Also, in this embodiment, the second temperature sensor S2 was a contact type thermistor, but for example, the second temperature sensor may be a non-contact type thermistor. Furthermore, at least one of the first temperature sensor and the second temperature sensor may be a temperature sensor other than a thermistor.

[0130] In the embodiment, the heating member 81 had a heater 81A and a heating roller 81R, but for example, the heating member may have a heater and an endless belt that rotates around the heater. Also, in the embodiment, a pressure roller 82 was exemplified as the pressure member, but for example, the pressure member may have an endless belt and a pad that is positioned inside the belt and sandwiches the belt between itself and the heating member.

[0131] In this embodiment, the image forming apparatus 1 was a printer capable of forming color images, but for example, the image forming apparatus may be a printer capable of forming only monochrome images. Alternatively, the image forming apparatus may be a copier, a multifunction printer, or the like.

[0132] The elements described in the above embodiments and modifications may be implemented in any combination. [Explanation of Symbols]

[0133] 1. Image forming apparatus 10 Main Unit 80 Fixing device 81 Heating element 81A Heater 82 Pressure roller (pressure component) 150 Fuser Connector 160 Main unit connector 210 First side frame 220 Second side frame 230 connection frames 240 relay board S Seat S1 First temperature sensor S2 Second temperature sensor

Claims

1. A fixing device that can be attached to the main housing of an image forming apparatus, A heating element extending in the longitudinal direction and having a heater, A pressurizing member extending in the longitudinal direction and nipping the sheet between itself and the heating member, A first temperature sensor for detecting the temperature of the heating element, A second temperature sensor for detecting the temperature of the heating element, the second temperature sensor being positioned at a different location from the first temperature sensor in the longitudinal direction, A fixing connector that can be connected to the main body connector of the main body housing, A relay board that relays the signal from the first temperature sensor to the fuser connector and relays the signal from the second temperature sensor to the fuser connector, A first side frame is positioned on one side of the heating member in the longitudinal direction, A second side frame is positioned on the other side of the heating member in the longitudinal direction, A metal connecting frame connecting the first side frame and the second side frame, comprising a connecting frame connected to the ground of the main housing, A fixing device characterized in that the ground of the relay board is electrically connected to the connecting frame.

2. The aforementioned fuser connector has a fuser ground terminal, The main unit connector has a main unit ground terminal connected to the ground of the main unit housing, The fixing device according to claim 1, characterized in that the fixing ground terminal is connected to the ground of the main body housing via the main body ground terminal when the fixing connector is attached to the main body connector.

3. The fixing connector has a plurality of terminals, including the fixing ground terminal. The fixing device according to claim 2, characterized in that the fixing ground terminal protrudes downstream of the other terminals in the direction of connection of the fixing connector to the main body connector.

4. The fixing device according to claim 1, further comprising a compression coil spring that provides electrical conductivity between the ground of the relay board and the connecting frame, the compression coil spring being disposed between the relay board and the connecting frame.

5. A resin frame is disposed between the relay board and the connecting frame, The relay board is further equipped with screws for fixing it to the resin frame, The relay board is long in the longitudinal direction, The resin frame has a claw that engages with one end of the relay substrate in the longitudinal direction, The fixing device according to claim 4, characterized in that the screw fixes the other end of the relay substrate to the resin frame in the longitudinal direction.

6. The compression coil spring is positioned between the claw and the screw in the longitudinal direction. The fixing device according to claim 5, characterized in that, in the longitudinal direction, the distance from the screw to the compression coil spring is smaller than the distance from the compression coil spring to the center of the relay substrate.

7. The compression coil spring comprises a coil and an arm extending from the end of the coil closest to the relay substrate. The fixing device according to claim 5, characterized in that the arm engages with the resin frame to restrict the rotation of the compression coil spring.

8. The fixing device according to claim 1, further comprising a contact portion that contacts the main body housing and is electrically connected to the ground of the main body housing when the fixing device is mounted on the main body housing, and which is electrically connected to the connecting frame.

9. The fixing device according to claim 8, characterized in that the contact portion is a boss extending in the longitudinal direction.

10. The first side frame is made of metal, The fixing device according to claim 9, characterized in that the boss is fixed to the first side frame.

11. The fixing device according to claim 8, characterized in that the contact portion contacts the main body housing and makes electrical contact with the ground of the main body housing before the fixing connector is connected to the main body connector when the fixing device is mounted on the main body housing.

Images