Image-forming device

Abstract

To provide a technique capable of supplying power to each section of a motor for driving a conveyance roller, a process power supply section for supplying process power to a process section for forming an image in a sheet, and a device body as a fixing device in a state in which a cover is open and capable of shutting off power supply to each section of the device body when the fixing device is removed from the device body in a state in which the cover is open.SOLUTION: A fixation presence / absence detection switch 15 enables input of power to a motor drive circuit MD from an AC-DC conversion circuit 112C by connecting the AC-DC conversion circuit 112C and the motor drive circuit MD in a first state, and shuts off input of power to the motor drive circuit MD from the AC-DC conversion circuit 112C by disconnecting the AC-DC conversion circuit 112C from the motor drive circuit MD in a second state.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present application relates to an image forming apparatus that forms a developer image on a sheet by a process unit, and that has a removable fixing device that fixes the developer image formed on the sheet. [Background technology]

[0002] The image forming apparatus of Patent Document 1 includes a fixing unit that is detachable when the cover arranged on the apparatus body is open, a first switch that cuts off an AC power supply line that supplies AC driving power to the fixing heater when the user opens the cover, and a second switch that cuts off the AC power supply line when the user removes the fixing unit. In the image forming apparatus of Patent Document 1, the supply of AC driving power from the apparatus body to the heater is cut off in conjunction with the user opening the cover. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-209486 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in an image forming device that performs straight discharge in which a sheet that has passed through the fixing device is discharged onto the cover with the cover open, as in the image forming device of Patent Document 1, if the power supply from the device body to the heater is cut off when the cover is opened, the developer image cannot be fixed onto the sheet, and therefore this configuration cannot be applied.

[0005] The image forming apparatus of the present application aims to provide technology that enables power to be supplied to each part of the device main body, which is the fixing device, even when the cover is open, including a motor that drives the conveying rollers, a process power supply unit that supplies process power to a process unit that forms an image on a sheet, and the various parts of the device main body, such as the fixing device, and that can cut off the power supply to each part of the device main body when the fixing device is removed from the device main body with the cover open. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the image forming apparatus of the present application comprises a main body housing having an opening, a cover capable of opening and closing the opening of the main body housing, a process unit that forms a developer image on a sheet, a fixing device that fixes the developer image formed on the sheet by the process unit, the fixing device being removable from the opening of the main body housing when the cover is open, a power output unit that outputs power, a transport roller that transports a sheet toward the process unit and the fixing device, a motor that drives and rotates the transport roller, a motor drive circuit that receives power from the power output unit and rotates the motor based on the power, and a switch that is in a first state when the fixing device is attached to the main body housing and in a second state when the fixing device is detached from the main body housing, wherein the switch enables the input of power from the power output unit to the motor drive circuit by connecting the power output unit and the motor drive circuit when in the first state, and blocks the input of power from the power output unit to the motor drive circuit by disconnecting the power output unit and the motor drive circuit when in the second state.

[0007] The image forming apparatus of the present application is provided with a switch that is turned on (first state) when the fixing device is attached to the main body housing, regardless of whether the cover is open or closed, and is turned off (second state) when the fixing device is removed from the main body housing. Regardless of whether the cover is open or closed, when the switch is in the first state, power can be input from the power output unit to the motor drive circuit, so that even when the cover of the image forming apparatus is open, the image forming apparatus can discharge a sheet that is conveyed via the process unit and the fixing device to the cover. On the other hand, when the cover is open and the fixing device is removed by a user, the image forming apparatus can cut off the input of power from the power output unit to the motor drive circuit using the switch.

[0008] The switch is also characterized in that, when in the first state, it inputs power from the power output section to the motor drive circuit.

[0009] This allows power to actually be input from the power output unit to the motor drive circuit, so that even when the cover of the image forming device is open, the image forming device can eject a sheet that is transported through the process unit and fixing device into the cover.

[0010] The image forming apparatus of the present application further includes a process power supply unit that supplies process power to the process unit based on power input from the power output unit, and the switch is further characterized in that, when in a first state, the switch enables the input of power from the power output unit to the process power supply unit by connecting the power output unit and the process power supply unit, and, when in a second state, the switch blocks the input of power from the power output unit to the process power supply unit by disconnecting the power output unit and the process power supply unit.

[0011] As a result, regardless of whether the cover is open or closed, when the switch is in the first state, power can be input from the power output unit to the process power supply unit, so that even when the cover of the image forming apparatus is open, the image forming apparatus can discharge a sheet that is transported via the process unit and the fixing device to the cover. On the other hand, when the cover is open and the fixing device is removed by a user, the image forming apparatus can cut off the input of power from the power output unit to the process power supply unit using the switch.

[0012] The image forming apparatus of the present application further includes a control unit and an on / off circuit that switches whether or not the power output by the power output unit is input to the process power supply unit, wherein the switch inputs power to the on / off circuit when in a first state and does not input power to the on / off circuit when in a second state, and the on / off circuit switches whether or not power is input from the power output unit to the process power supply unit depending on whether or not an instruction is given from the control unit when power is input to the on / off circuit by the switch.

[0013] This makes it possible for the on / off circuit to switch whether or not to input power from the power output unit to the process power supply unit depending on whether or not an instruction is received from the control unit, even when the fixing device is attached to the main body housing.

[0014] The image forming apparatus of the present application further includes a main body connector, a first power supply board having a power output section and receiving AC power supplied from a commercial power source, and an input terminal receiving AC power from the commercial power source, and the fixing device has a heater connected to the input terminal via a relay, and a fixing connector connected to the main body connector when the fixing device is attached to the main body housing, and the first power supply board supplies AC power to the heater via the main body connector and the fixing connector.

[0015] This enables the first power supply board to supply AC power to the heater via the main body connector and the fixing connector.

[0016] The image forming apparatus of the present application further includes a second power supply board having a process power supply unit and generating process power to be supplied to the process unit, the second power supply board being arranged on one side of the main body housing so that the board surface and the one side are parallel to each other, and a main board having a control unit being arranged on the other side opposite the one side so that the board surface and the other side are parallel to each other, the main body connector being arranged on the one side, the fixing connector being arranged on the one side when the fixing device is attached to the main body housing, the main board and the second power supply board being connected by a first connection line arranged along the ceiling surface side or bottom surface side within the main body housing, the second power supply board and the main body connector being connected by a second connection line, and the main board being connected to the fixing device via the first connection line, the second power supply board, the second connection line, the main body connector, and the fixing connector.

[0017] As a result, the main board is connected to the fixing device via the first connection line, the second power board, the second connection line, the main connector, and the fixing connector, so it is possible to omit the connection line connecting the main board and the main connector, which makes it possible to reduce the size of the main housing because the path for the connection line connecting the main board and the main connector is no longer necessary.

[0018] The image forming apparatus of the present application further includes an output tray onto which sheets having developer images fixed by the fixing device are output, and a cover sensor for detecting whether the cover is open or closed, and the control unit, when receiving a print command, controls to perform normal output, in which the sheet that has passed through the process unit and the fixing device is output to the output tray, if the switch is in a first state and the cover sensor detects that the cover is closed, and when receiving a print command, controls to perform straight output, in which the sheet that has passed through the process unit and the fixing device is output to the cover, if the switch is in the first state and the cover sensor detects that the cover is open, and when performing straight output, instructs the relay to cut off the connection between the input terminal and the heater when the switch switches from the first state to the second state.

[0019] This makes it possible to interrupt straight discharge when the switch is switched from the first state to the second state while the straight discharge is being executed.

[0020] The image forming apparatus of the present application comprises a power line for inputting the power output from a power output unit to each of a motor drive circuit, a control unit and an on / off circuit, the power line extending via a switch, the power line branching from the power output unit via the switch at a first branch point downstream and connected to the motor drive circuit, branching from the power output unit via the switch at a second branch point downstream and connected to the control unit, and connected to the on / off circuit at an end via the power output unit via the switch.

[0021] This makes it possible for one power line to be shared by the motor drive circuit, the control unit, and the on / off circuit.

[0022] The fixing device further has a gripping portion that is gripped by a user, a lever that is rotatable between a first position and a second position around a lever axis, and a switch abutment portion that can abut against a switch, and when the gripping portion is not gripped, the switch is in the first state when the lever is in the first position and the switch abutment portion abuts against the switch, and when the gripping portion is gripped, the lever rotates from the first position to the second position and the switch abutment portion moves away, thereby entering the second state.

[0023] This makes it possible to accurately detect, using the switch, whether the fixing device is attached to or detached from the main body housing.

[0024] In addition, the cover is characterized in that, when it is open, a sheet to be transported via the process section and the fixing device can be placed on it.

[0025] This allows the sheet to be discharged straight onto the cover.

[0026] In order to achieve the above-mentioned object, the image forming apparatus of the present application comprises a main body housing having an opening, a cover capable of opening and closing the opening of the main body housing, a process unit that forms a developer image on a sheet, a fixing device that fixes the developer image formed on the sheet by the process unit, the fixing device being removable from the opening of the main body housing when the cover is open, a power output unit that outputs power, a process power supply unit that supplies process power to the process unit based on power input from the power output unit, and a switch that is in a first state when the fixing device is attached to the main body housing and in a second state when the fixing device is detached from the main body housing, wherein the switch enables the input of power from the power output unit to the process power supply unit by connecting the power output unit and the process power supply unit when in the first state, and blocks the input of power from the power output unit to the process power supply unit by disconnecting the power output unit and the process power supply unit when in the second state.

[0027] The image forming apparatus of the present application is provided with a switch that is turned on when the fixing device is attached to the main body housing and turned off when the fixing device is removed from the main body housing, regardless of whether the cover is open or closed. Regardless of whether the cover is open or closed, when the switch is in a first state, power can be input from the power output unit to the process power supply unit, so that the image forming apparatus can discharge a sheet conveyed via the process unit and the fixing device to the cover even when the cover of the image forming apparatus is open. On the other hand, when the fixing device is removed by a user with the cover open, the image forming apparatus can cut off the input of power from the power output unit to the process power supply unit using the switch.

[0028] In addition, the image forming apparatus of the present application further includes a control unit and an on / off circuit that switches whether or not the power generated by the power output unit is input to the process power supply unit, wherein the switch inputs power to the on / off circuit when in a first state and does not input power to the on / off circuit when in a second state, and the on / off circuit switches whether or not to input power from the power output unit to the process power supply unit depending on whether or not an instruction is given from the control unit when power is input to the on / off circuit by the switch.

[0029] This makes it possible for the on / off circuit to switch whether or not to input power from the power output unit to the process power supply unit depending on whether or not an instruction is received from the control unit, even when the fixing device is attached to the main body housing.

[0030] The image forming apparatus of the present application further includes a main body connector, a first power supply board having a power output unit and receiving AC power supplied from a commercial power supply, and an input terminal receiving the AC power supplied from the commercial power supply, the fixing device including a heater connected to the input terminal via a relay, and a fixing connector connected to the main body connector when the fixing device is attached to the main body housing and supplying AC power to the heater via the relay and the main body connector, the first power supply board including a power output unit and supplying AC power to the heater via the main body connector and the fixing connector, and the control unit instructs the relay to cut off connection between the input terminal and the heater when the switch is switched from a first state to a second state with the cover open during an image forming operation.

[0031] This enables the first power supply board to supply AC power to the heater via the main body connector and the fixing connector. [Brief description of the drawings]

[0032] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a color laser printer according to an embodiment of the present application. [Diagram 2]2 is a perspective view showing the color laser printer of FIG. 1 with a rear cover open. [Diagram 3] 3 is a perspective view showing a state in which the fixing device is pulled out from the state shown in FIG. 2. [Figure 4] FIG. 4A shows a state in which the fixing device is located at the mounting position and the lever is located at a first position, and FIG. 4B shows a state in which the lever is located at a second position. [Diagram 5] 2 is a top view showing a schematic internal configuration of the color laser printer shown in FIG. 1. [Figure 6] 2 is a block diagram showing the transmission paths of some signals within the color laser printer of FIG. 1. [Figure 7] 7 is a diagram showing a detailed circuit configuration of a portion of the circuit provided on the main board of FIG. 6. [Figure 8] 7 is a flowchart showing a procedure of a control process executed by an ASIC provided on the main board of FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] Hereinafter, embodiments of the present application will be described in detail with reference to the drawings.

[0034] FIG. 1 is a cross-sectional view showing a schematic configuration of a color laser printer 1 according to an embodiment of the present application. The color laser printer 1 is an example of an image forming device. Hereinafter, the color laser printer 1 will be abbreviated to printer 1. The printer 1 comprises a main body housing 2, a conveying unit 3, a process unit 4, and a fixing device 9. Hereinafter, for convenience of explanation, the up-down direction and the front-rear direction of the printer 1 will be defined as shown by the arrows in FIG. 1. In addition, the side of the paper will be defined as the right, and the other side of the paper will be defined as the left.

[0035] The main body housing 2 has a front cover 21, a rear cover 12, a supply tray 31, a discharge tray 22, and first to third transport paths 25 to 27. The front cover 21 is a cover for opening and closing a front opening 2A provided at the front of the main body housing 2, and is attached to the front surface of the main body housing 2 in an openable and closable state. The rear cover 12 is a cover for opening and closing a rear opening 2B provided at the rear of the main body housing 2, and is attached to the rear surface of the main body housing 2 in an openable and closable state. The supply tray 31 is attached to the lower part of the main body housing 2 in a detachable state. A sheet S is placed on the supply tray 31. The sheet S is a standard sheet such as an A4 size. The sheet S is, for example, a paper medium such as plain paper or thick paper, but is not limited thereto and may be an OHP film. The discharge tray 22 is provided at the upper part of the main body housing 2, and a sheet S on which an image is formed is placed on the discharge tray 22.

[0036] The conveying section 3 has a pickup roller 33, a separation roller 34, a registration roller 35, a first conveying roller 36, a second conveying roller 37, a first switchback roller 38, a second switchback roller 39, a plurality of third conveying rollers 40, a flapper 30, and a main motor 106 (see FIG. 6). A part of the second conveying path 26 is formed by the rear cover 12 in the closed state.

[0037] The pickup roller 33 picks up the sheets S in the supply tray 31 that have been pushed upward by the sheet pressing plate 32, and transports the sheets S toward the first transport path 25. The separation roller 34 separates the sheets S picked up by the pickup roller 33 one by one.

[0038] The registration rollers 35 are disposed upstream of the process unit 4 on the first transport path 25. The registration rollers 35 align the direction of the leading edge of the sheet S, and then transport the sheet S toward the process unit 4. The transport direction in which the registration rollers 35 transport the sheet is from the front to the rear.

[0039] When the conveying unit 3 conveys the sheet S outside the main body housing 2, if the rear cover 12 is closed, the conveying unit 3 conveys the sheet S conveyed from the process unit 4 by the first conveying roller 36, and guides the sheet S to the first conveying path 25 by the flapper 30 (30A). Thereafter, the conveying unit 3 conveys the sheet S guided to the first conveying path 25 by the second conveying roller 37 and the first switchback roller 38, and discharges the sheet S onto the discharge tray 22.

[0040] Furthermore, when the conveying unit 3 conveys the sheet S out of the main body housing 2, if the rear cover 12 is open, the sheet S conveyed from the process unit 4 is conveyed by the first conveying roller 36, guided rearward by the flapper 30 (30B) swung to the position shown by the imaginary line, and discharged onto the open rear cover 12 through the rear opening 2B. In this embodiment, this discharge method is called straight discharge. The printer 1 is capable of forming an image on the sheet S even with the rear cover 12 open, and the rear cover 12 is a cover that enables the sheet S on which an image has been formed to be discharged from the rear opening 2B when open.

[0041] Furthermore, when the conveying unit 3 conveys the sheet S again to the process unit 4, the sheet S conveyed from the process unit 4 is conveyed by the first conveying roller 36, and is guided to the first conveying path 25 or the second conveying path 26 by the flapper 30. When the sheet S is guided to the first conveying path 25, the conveying unit 3 conveys the sheet S in the first conveying path 25 to the third conveying path 27 by the second conveying roller 37 and the first switchback roller 38. When the sheet S is guided to the second conveying path 26, the conveying unit 3 conveys the sheet S in the second conveying path 26 to the third conveying path 27 by the second switchback roller 39.

[0042] The sheet S conveyed to the third conveying path 27 is supplied again to the processing unit 4 by the third conveying roller 40, the registration roller 35, etc. Thereafter, an image is formed on the sheet S in the processing unit 4, and then the sheet S is discharged onto the discharge tray 22 by the conveying unit 3.

[0043] The process unit 4 has a function of forming an image on the sheet S, and transfers a toner image onto the sheet S. The process unit 4 includes an exposure unit 5, a drum unit 6, four developing cartridges 7Y, 7M, 7C, and 7K, and a transfer unit 8.

[0044] The exposure unit 5 is disposed in the upper part of the main body housing 2, and includes a light source, a polygon mirror, a lens, a reflecting mirror, etc. (not shown). The exposure unit 5 exposes the surface of the photoconductor drum 61 by emitting a light beam indicated by a dashed dotted line to the surface of the photoconductor drum 61.

[0045] The drum unit 6 is disposed between the supply tray 31 and the exposure unit 5 inside the main body housing 2, and includes four photosensitive drums 61, four chargers 62, a pinch roller 64, and a support frame 65 that supports the photosensitive drums 61 and the like. The drum unit 6 is detachable from the main body housing 2 through the front opening 2A when the front cover 11 is open. The pinch roller 64 faces the registration roller 35. The pinch roller 64 rotates following the rotation of the registration roller 35, and transports the sheet S together with the registration roller 35.

[0046] The developing cartridges 7Y, 7M, 7C, and 7K correspond to the four colors of yellow (Y), magenta (M), cyan (C), and black (K), respectively, and are removably mounted in the drum unit 6 in the stated order from the front to the rear of the printer 1. Each of the developing cartridges 7Y, 7M, 7C, and 7K includes a developing roller 71, a supply roller 72, and a toner storage section 73. Although the developing cartridges 7Y, 7M, 7C, and 7K differ in toner color, the rest of the configuration is the same, and therefore, hereinafter, any one of the developing cartridges may be referred to as the developing cartridge 7.

[0047] The transfer unit 8 is disposed between the supply tray 31 and the drum unit 6 inside the main body housing 2, and includes a drive roller 81, a driven roller 82, a conveyor belt 83, and four transfer rollers 84. The conveyor belt 83 is stretched between the drive roller 81 and the driven roller 82, and its upper surface is in contact with the photosensitive drum 61. The four transfer rollers 84 are disposed inside the conveyor belt 83 so as to sandwich the conveyor belt 83 between the corresponding photosensitive drum 61.

[0048] The fixing device 9 is disposed behind the process unit 4 inside the main body housing 2. More specifically, the fixing device 9 is disposed between the rear cover 12 in a closed state and the process unit 4. The fixing device 9 has a heating roller 91 that heats the sheet S, and a pressure unit 92 that sandwiches the sheet S between the heating roller 91. In this embodiment, the heating roller 91 has a heater 93 therein that heats the heating roller 91. The pressure unit 92 has an endless belt (not shown with the reference numerals omitted), a pressure pad that sandwiches the endless belt between the heating roller 91, a holder that supports the pressure pad, a belt guide, and the like.

[0049] In the process unit 4, the charger 62 uniformly charges the surface of the photoconductor drum 61, and the exposure unit 5 exposes the surface of the photoconductor drum 61 to light, thereby forming an electrostatic latent image on the surface of the photoconductor drum 61. In addition, the process unit 4 supplies toner in a toner storage unit 73 to a supply roller 72, which then supplies the toner to the developing roller 71. The toner supplied to the developing roller 71 is carried on the developing roller 71 as the developing roller 71 rotates.

[0050] The process unit 4 supplies the toner carried on the development roller 71 to the electrostatic latent image formed on the photoreceptor drum 61, thereby forming a toner image on the surface of the photoreceptor drum 61. Thereafter, the process unit 4 transfers the toner image on the photoreceptor drum 61 to the sheet S by transporting the sheet S supplied from the supply tray 31 by the transport unit 3 between the photoreceptor drum 61 and the transport belt 83. Thereafter, the process unit 4 transports the sheet S to the fixing device 9.

[0051] The fixing device 9 fixes the toner image transferred onto the sheet S onto the sheet S by conveying the sheet S between a heating roller 91 and a pressure unit 92, thereby forming an image on the sheet S.

[0052] The printer 1 further includes, within the main body housing 2, a fixing fan 13 and a fixing temperature sensor TH.

[0053] Fixing fan 13 is provided so as to exhaust air inside main body housing 2 to the outside of main body housing 2 when driven.

[0054] The fixing temperature sensor TH is a temperature sensor that outputs a signal corresponding to the temperature of the fixing device 9, more specifically, the temperature of the heating roller 91. The fixing temperature sensor TH is provided in the fixing device 9 and disposed facing the heating roller 91 in a non-contact state. As the fixing temperature sensor TH, for example, a non-contact thermistor or the like can be used.

[0055] The fixing device 9 can be attached to and detached from the main body housing 2 through a rear opening 2B of the main body housing 2, which is opened by opening the rear cover 12. Fig. 2 shows the state in which the rear cover 12 is open. As shown in Fig. 2, the fixing device 9 includes a fixing housing 120, a fixed handle 130, and a lever 140. The fixed handles 130 are provided on both the left and right ends of the fixing housing 120, and the levers 140 are attached to the fixed handles 130.

[0056] 3, when the user pulls each fixed handle 130 backward while gripping each lever 140, the fixing device 9 can be detached from the main body housing 2. At this time, the fixing connector 160 provided on the fixing device 9 is also detached from the main body connector 150 provided on the main body housing 2. In other words, the fixing connector 160 and the main body connector 150 are connected when the fixing device 9 is attached to the main body housing 2, and are detached when the fixing device 9 is detached from the main body housing 2.

[0057] As shown in Fig. 4, the lever 140 is formed in an L-shape and is configured to be rotatable about a lever shaft 140A between a first position shown in Fig. 4(a) and a second position shown in Fig. 4(b). In this embodiment, the axial direction of the lever shaft 140A is the width direction of the seat S, that is, the left-right direction. The spring SP is a compression spring disposed between the fixed handle 130 and the lever 140. The spring SP constantly biases the lever 140 from the second position toward the first position.

[0058] Lever 140 has a main body portion 141, a grip portion 142, a switch contact portion 143, an engagement portion 144, and a pressed portion 145. Of the two levers 140, the lever 140 provided at the end on one side (for example, the right side) in the left-right direction of fixing housing 120 does not have the switch contact portion 143.

[0059] The main body 141 extends from the lever shaft 140A in the forward direction, and the grip 142 extends from the lever shaft 140A in the upward direction. That is, the grip 142 extends in a direction different from that of the main body 141, and forms an L shape together with the main body 141. The grip 142 is gripped when the fixing device 9 is removed from the main body housing 2. When the user grips both the fixed handle 130 and the grip 142 and moves the grip 142 closer to the fixed handle 130, the lever 140 moves from the first position shown in FIG. 4(a) to the second position shown in FIG. 4(b). That is, the grip 142 is closer to the fixed handle 130 when the lever 140 is in the second position than when the lever 140 is in the first position.

[0060] The switch abutment portion 143 is a projection extending downward from the front end portion of the main body portion 141, and projects in the rotation direction of the lever 140. As shown in FIG. 4(a), when the lever 140 is located at the first position, the switch abutment portion 143 enters the switch hole 16. When the switch abutment portion 143 enters the switch hole 16 provided in the main body housing 2, the switch abutment portion 143 can abut against the arm portion 15A of the fixing presence / absence detection switch 15.

[0061] 4(a), when the fixing device 9 is attached to the main body housing 2 and the grip portion 142 is not gripped, the lever 140 is located at the first position and the switch abutment portion 143 abuts against the arm portion 15A of the fixing presence / absence detection switch 15, thereby turning the fixing presence / absence detection switch 15 to the ON state (first state). On the other hand, when the fixing device 9 is attached to the main body housing 2 and the grip portion 142 is gripped, the lever 140 rotates from the first position to the second position and the switch abutment portion 143 moves away from the arm portion 15A of the fixing presence / absence detection switch 15, thereby turning the fixing presence / absence detection switch 15 to the OFF state (second state) as shown in FIG.

[0062] The engaging portion 146 is a protrusion that extends downward from the rear end of the main body 141 and protrudes in the rotation direction of the lever 140. In this embodiment, the engaging portion 146 has a hook shape with a tip that is bent in the removal direction.

[0063] As shown in FIG. 4(a), when the lever 140 is located at the first position, the engagement portion 146 enters into the engagement hole 17 provided in the main body housing 2. When the engagement portion 146 enters into the engagement hole 17, the engagement portion 146 is able to engage with the main body housing 2. When the engagement portion 146 engages with the main body housing 2, it prevents the fixing device 9 from being removed from the main body housing 2. On the other hand, as shown in FIG. 4(b), when the lever 140 is located at the second position, the engagement portion 146 does not engage with the main body housing 2 and does not prevent the fixing device 9 from being removed from the main body housing 2.

[0064] Next, the internal configuration of the printer 1 will be described with reference to Fig. 5. Note that Fig. 5 mainly describes components necessary for explaining this embodiment, and omits other components of the printer 1.

[0065] As shown in FIG. 5, the printer 1 includes a sheet metal frame 48, a first resin frame 49A, and a second resin frame 49B inside the main body housing 2. The first resin frame 49A, the second resin frame 49B, and the support frame 49C constitute the main body frame 49. The first resin frame 49A and the second resin frame 49B are connected via the support frame 49C. Hereinafter, the vertices of the opposing first resin frame 49A and the second resin frame 49B are connected to each other to form a rectangular parallelepiped shape. Hereinafter, the inside of this rectangular parallelepiped shape will be referred to as the inside of the main body frame 49, and the outside of this rectangular parallelepiped shape will be referred to as the outside of the main body frame 49. The sheet metal frame 48 is grounded. The first resin frame 49A, the second resin frame 49B, and the support frame 49C are made of resin, but may be made of other materials such as metal instead of resin.

[0066] The main board 100, the main motor 106, and the process motor 107 are disposed on the left side of the sheet metal frame 48. That is, the main board 100, the main motor 106, and the process motor 107 are disposed on the left side of the outside of the main body frame 49. The main motor 106 is mounted on the main motor board 106A, and the process motor 107 is mounted on the process motor board 107A. The main board 100 and the main motor board 106A are connected via a first motor harness MHR1, and the main board 100 and the process motor board 107A are connected via a second motor harness MHR2. When the main motor 106 is driven, the heating roller 91 of the fixing device 9 and the roller of the conveying unit 3 rotate. When the process motor 107 is driven, the photosensitive drum 61 and the developing roller 71 rotate.

[0067] The fixing fan 13 is disposed on the second resin frame 49B, and a high-voltage power supply board 114 is disposed on the right side of the second resin frame 49B. That is, the fixing fan 13 and the high-voltage power supply board 114 are disposed on the right side of the main body frame 49. The high-voltage power supply board 114 supplies high voltages HV (see FIG. 7) such as a developing voltage and a charging voltage to the process unit 4. The high-voltage power supply board 114 has a high-voltage generating circuit 114C (see FIG. 6). The high-voltage generating circuit 114C generates a high voltage HV of, for example, about 1 kV based on a DC voltage, for example, DC 24 V, supplied from the AC-DC power supply board 112 via the main board 100, and supplies the high voltage HV to the process unit 4.

[0068] The left side of the main body frame 49 is crowded because the drive system, such as the main motor 106, the process motor 107, and gears (not shown), is arranged there. However, the main board 100 must be arranged near the motors 106 and 107, so it has to be arranged on the left side of the main body frame 49. In contrast, the right side of the main body frame 49 has relatively more space, even though the high-voltage power supply board 114 is arranged there. For this reason, the main body connector 150 is arranged on the right side of the main body frame 49, that is, on the right side of the main body housing 2. This inevitably determines the position of the fixing connector 160, and the fixing connector 160 is arranged at a position where it fits into the main body connector 150 when the fixing device 9 is attached to the main body housing 2. In other words, the fixing connector 160 is arranged at the right end of the fixing housing 120 in FIG. 3.

[0069] The main board 100 and the high-voltage power supply board 114 are connected via a first connection line CA1. The ASIC 101 (see FIG. 6) mounted on the main board 100 needs to exchange control signals between the main board 100 and the high-voltage power supply board 114 in order to control the high-voltage power supply board 114. The first connection line CA1 is for transmitting these control signals. Since there are multiple control signals, there are also multiple signal lines for transmitting the multiple control signals. Therefore, the first connection line CA1 is configured by a harness that bundles multiple signal lines. Furthermore, a flat cable is adopted as the cable shape. The flat cable is adopted in order to reduce the volume of the cable path as much as possible and thereby suppress the size of the main body housing 2.

[0070] As described above, the main board 100 is disposed on the left side of the main frame 49, and the high-voltage power supply board 114 is disposed on the right side of the main frame 49, so the first connection line CA1 connecting the main board 100 and the high-voltage power supply board 114 needs to traverse the main frame 49 from left to right. The first connection line CA1 is disposed along the ceiling surface side within the main body housing 2 in the example of Fig. 5, but is not limited to this, and may be disposed along the bottom surface side within the main body housing 2.

[0071] The AC-DC power supply board 112 is disposed behind the bottom side inside the main body frame 49, below the fixing device 9, parallel to the bottom surface of the main body frame 49 and lying in the left-right direction. The AC-DC power supply board 112 has an AC-DC conversion circuit 112C (see FIG. 6), and inputs an AC voltage supplied by a commercial power source, for example, AC 100V, and converts this AC 100V into a DC voltage, for example, DC 24V, by the AC-DC conversion circuit 112C. The AC-DC power supply board 112 is connected to the main board 100 via a fourth connection line CA4, and outputs the generated DC 24V to the main board 100.

[0072] The main board 100 has a DC-DC conversion circuit 102 (see FIG. 6), and converts DC 24V from the AC-DC power supply board 112 to, for example, DC 3.3V by the DC-DC conversion circuit 102. This DC 3.3V is a voltage for driving various electronic components mounted on the main board 100. However, if there are electronic components that are driven by another DC voltage value, for example, DC 5V, multiple DC-DC conversion circuits may be provided to generate DC 5V in addition to DC 3.3V.

[0073] The AC-DC power supply board 112 is connected to the main body connector 150 via a third connection line CA3, and is connected to the inlet 200 (see FIG. 6) via a fifth connection line CA5. The inlet 200 is for inputting an AC voltage (AC 100V) supplied from a commercial power source, and this AC voltage is supplied to the fixing device 9 from the inlet 200 via the fifth connection line CA5, the AC-DC power supply board 112, the third connection line CA3, the main body connector 150, and the fixing connector 160. The inlet 200 is provided at the rear end of the second resin frame 49B. Therefore, the AC-DC power supply board 112 converts the AC voltage input from the right side of the main body housing 2 into a DC voltage (24V), and outputs the DC voltage to the main board 100 on the left side of the main body housing 2 via the fourth connection line CA4.

[0074] Fig. 6 shows some signal transmission paths within the printer 1. As shown in Fig. 6, an ASIC 101 is mounted on the main board 100. The ASIC 101 has, for example, a CPU, a ROM, a RAM, and an input / output circuit (none of which are shown), and controls the entire printer 1 including the processing unit 4 by performing various arithmetic processing based on programs and data stored in the ROM or the like.

[0075] In addition to the ASIC 101, the main board 100 is provided with a motor drive circuit MD for driving the main motor 106, an on / off circuit 103 for switching whether or not to supply DC 24V to the high voltage generation circuit 114C of the high voltage power supply board 114, a detection circuit (DET) 104 for detecting whether the fixing presence / absence detection switch 15 is in the on or off state, and the DC-DC conversion circuit 102.

[0076] The AC-DC conversion circuit 112C of the AC-DC power supply board 112 is connected to the DC-DC conversion circuit 102 via a power line PL. The power line PL connecting the AC-DC conversion circuit 112C and the DC-DC conversion circuit 102 is included in the fourth connection line CA4. The power line PL branches off at a branch point BP0 on the main board 100 before being input to the DC-DC conversion circuit 102, and extends therefrom, and is connected to the input side of the fixing presence / absence detection switch 15.

[0077] The output side of the fixed-fixed detection switch 15 is connected to the input side of the ON / OFF circuit 103 via the power line PL, branches off at a first branch point BP1 on the power line PL located between the output side of the fixed-fixed detection switch 15 and the input side of the ON / OFF circuit 103, and is connected to the input side of the motor drive circuit MD. Furthermore, the output side of the fixed-fixed detection switch 15 branches off at a second branch point BR2 downstream of the first branch point BP1 on the power line PL located between the output side of the fixed-fixed detection switch 15 and the input side of the ON / OFF circuit 103, and is connected to the input side of the detection circuit 104.

[0078] The output side of the motor drive circuit MD is connected to the main motor 106. As shown in Fig. 7, the motor drive circuit MD is supplied with a voltage applied to a first branch point BP1 on the power line PL. Since the output voltage from the fixed / unfixed detection switch 15 is applied to the first branch point BP1, when the fixed / unfixed detection switch 15 is in the ON state, DC 24 V is applied, and when the fixed / unfixed detection switch 15 is in the OFF state, 0 V is applied.

[0079] Further, a signal EN is input to the motor drive circuit MD from the output port EN of the ASIC 101. The signal EN is a signal for enabling or disabling the motor drive circuit MD. For example, when the value of the signal EN is H, the motor drive circuit MD is in an operable state, and when the value of the signal EN is L, the motor drive circuit MD is in an inoperable state. However, even if the signal EN of H is input to the motor drive circuit MD, the motor drive circuit MD does not operate when DC24V is not applied to the motor drive circuit MD. In other words, when the signal EN of H is input with DC24V applied to the motor drive circuit MD, the motor drive circuit MD starts operating, and when the signal EN of L is input with DC24V applied to the motor drive circuit MD, the motor drive circuit MD stops operating. Therefore, when 0V is applied to the motor drive circuit MD, the motor drive circuit MD stops operating regardless of the value of the signal EN. Note that a well-known method may be used as a method for the motor drive circuit MD to control the main motor 106, and therefore a description thereof will be omitted.

[0080] 6, the output side of the on / off circuit 103 is connected to the power supply voltage input side of the high voltage generation circuit 114C of the high voltage power supply board 114. A control signal is also input to the high voltage generation circuit 114C from an output port (not shown) of the ASIC 101. The high voltage generation circuit 114C has, for example, a boost circuit including a transformer and a transformer drive circuit, and as described above, boosts the input DC 24V based on the input control signal, and supplies the generated high voltage HV, specifically, the charging voltage, the developing voltage, and the transfer voltage (see FIG. 7), to the process unit 4.

[0081] In addition to the output voltage from the fixing detection switch 15, the on / off circuit 103 is supplied with DC 24V, and further receives an HVEN signal from the ASIC 101. As shown in FIG. 7, the on / off circuit 103 is composed of two NPN transistors Q1 and Q2, one P-channel MOSFET 103A, and three resistors R1 to R3. The base of the transistor Q1 is connected to DC 3.3V via the resistor R1, and is also connected to the collector of the transistor Q2. The collector of the transistor Q1 is also connected to the output port HVEN of the ASIC 101, and is also connected to the gate of the FET 103A. The emitter of the transistor Q1 is grounded. The base of the transistor Q2 is connected to the output side of the fixing detection switch 15 via the resistor R2, and the emitter of the transistor Q2 is grounded. The second branch point BR2 is also grounded via the resistor R3. That is, the output voltage from the fixing state detection switch 15 is divided by the resistors R2 and R3. A voltage of DC 24 V is applied to the source of the FET 103A, and the drain of the FET 103A is connected to the power supply voltage input side of the high voltage generation circuit 114C.

[0082] ASIC 101 outputs an HVEN signal to on / off circuit 103. The HVEN signal is a signal for controlling on / off circuit 103, and takes on either an on (=H) or off (=L) value. The output voltage from fixing detection switch 15 is divided by resistors R2 and R3 and applied to the base of transistor Q2.

[0083] When DC24V is applied to the second branch point BR2, the voltage value between the base and emitter of the transistor Q2 becomes equal to or higher than a predetermined value, that is, a value that turns on the transistor Q2, and the transistor Q2 turns on. As a result, a current flows from the collector to the emitter of the transistor Q2, and the potential of the collector approaches the ground potential, so that the voltage applied to the base of the transistor Q1 becomes approximately 0V. As a result, the transistor Q1 turns off. At this time, when the ASIC 101 outputs the HVEN signal, the value of the HVEN signal, that is, the value of the HVEN signal, that is, ON or OFF, is input as it is to the gate of the FET 103A. Therefore, when the HVEN signal is ON, the FET 103A turns ON, and the DC24V applied to the source of the FET 103A is output as it is from the drain of the FET 103A, so that the DC24V is applied to the power supply voltage input side of the high voltage generating circuit 114C. On the other hand, at this time, when the HVEN signal is off, the FET 103A is turned off and the DC 24V applied to the source of the FET 103A is not output from the drain of the FET 103A, so that the power supply voltage input side of the high voltage generating circuit 114C remains at 0V.

[0084] On the other hand, when 0V is applied to the second branch point BR2, the voltage value between the base and emitter of the transistor Q2 also becomes 0V, and the transistor Q2 turns off. As a result, no current flows from the collector to the emitter of the transistor Q2, so the collector potential of the transistor Q2 is pulled up to DC 3.3V, and the base of the transistor Q1, which has the same potential as the collector of the transistor Q2, also becomes DC 3.3V, so the transistor Q1 turns on. At this time, when the ASIC 101 outputs the HVEN signal, when the value of the HVEN signal is on (=H), a current flows from the collector to the emitter of the transistor Q1, so the collector potential approaches the ground potential, and an L HVEN signal is input to the gate of the FET 103A. Therefore, the FET 103A turns off, and the DC 24V applied to the source of the FET 103A is not output from the drain of the FET 103A, so the power supply voltage input side of the high voltage generation circuit 114C remains at 0V. On the other hand, at this time, when the HVEN signal is off, the FET 103A is turned off and the DC 24V applied to the source of the FET 103A is not output from the drain of the FET 103A, so that the power supply voltage input side of the high voltage generating circuit 114C remains at 0V.

[0085] The above-described states of the HVEN signal, the fixing state detection switch 15, and the on / off circuit 103 can be summarized as shown in the following table. [Table 1]

[0086] That is, when DC 24V is input from the fixing state detection switch 15, the on / off circuit 103 switches whether or not DC 24V is input to the high voltage generating circuit 114C according to the value of the HVEN signal output from the ASIC 101.

[0087] Returning to Fig. 6, the output side of the detection circuit 104 is connected to an input port (not shown) of the ASIC 101. As shown in Fig. 7, the detection circuit 104 is composed of one NPN transistor Q3 and three resistors R11 to R13. The base of the transistor Q3 is connected to a second branch point BR2 of the power line PL via a resistor R12 and is grounded via a resistor R13. In addition, the emitter of the transistor Q3 is grounded, and the collector of the transistor Q3 is connected to DC 3.3V via a resistor R11 and is connected to an input port DET of the ASIC 101.

[0088] When the fixing detection switch 15 is turned on and DC 24V is applied to the second branch point BR2, the base-emitter voltage of the transistor Q3 becomes equal to or exceeds a predetermined value, that is, the value that turns on the transistor Q3, and the transistor Q3 turns on. As a result, a current flows from the collector to the emitter of the transistor Q3, and the collector potential approaches the ground potential, so that the ASIC 101 recognizes the detection signal DET output by the detection circuit 104 as L. On the other hand, when the fixing detection switch 15 is turned off and 0V is applied to the power line PL, the base-emitter voltage of the transistor Q3 also becomes 0V, and the transistor Q3 turns off. As a result, no current flows from the collector to the emitter of the transistor Q3, so the collector potential is pulled up to DC 3.3V, and the ASIC 101 recognizes the detection signal DET output by the detection circuit 104 as H. In this way, when the detection signal DET from the detection circuit 104 is L, the ASIC 101 determines that the fixing detection switch 15 is on, and when the detection signal DET from the detection circuit 104 is H, the ASIC 101 determines that the fixing detection switch 15 is off.

[0089] Returning to Fig. 6, an input port (not shown) of the ASIC 101 is connected to the output side of the rear cover open / close detection switch 14. The rear cover open / close detection switch 14 is provided near the rear cover 12, and outputs a rear cover open / close signal indicating a value according to whether the rear cover 12 is open or closed. The ASIC 101 can determine whether the rear cover 12 is open or closed by looking at the value of this rear cover open / close signal.

[0090] The main board 100 is connected to the high-voltage power supply board 114 via a connector 100A on the main board 100 side, a first connection line CA1, and a connector 114A on the high-voltage power supply board 114 side. The high-voltage power supply board 114 is connected to the main connector 150 via a connector 114B on the high-voltage power supply board 114 side and a second connection line CA2.

[0091] As described above, the main body housing 2 includes the inlet 200, and the AC voltage supplied from the inlet 200 is input to the AC-DC power supply board 112 via the connector 112A on the AC-DC power supply board 112 side. The AC-DC power supply board 112 is connected to the main body connector 150 via the connector 112B on the AC-DC power supply board 112 side and the third connection line CA3.

[0092] The main body connector 150 is connected to the fixing connector 160. The fixing connector 160 is connected to the fixing relay board 115 via the connector 115A on the fixing relay board 115 side. As described above, the fixing device 9 includes the heater 93. An AC voltage, for example, AC 100V, input from the inlet 200 is supplied to the heater 93 via the AC-DC power supply board 112, the third connection line CA3, the main body connector 150, and the fixing connector 160.

[0093] The heater 93 is heated by the AC 100V supplied in this manner. When AC 100V is supplied to the heater 93, the ASIC 101 controls the on / off timing of the AC 100V supplied to the heater 93, thereby controlling the heating temperature of the heater 93. In order to control this heating temperature, the fixing temperature sensor TH is provided as described above. In the example of FIG. 6, the fixing temperature sensor TH is composed of three temperature sensors TH1 to TH3. The temperature sensors TH1 to TH3 are respectively arranged at positions where they can detect the temperatures of the left end, center, and right end of the heating roller 91 which is long in the left-right direction.

[0094] Temperature sensors TH1 and TH3, which detect the temperatures at both the left and right ends of the heat roller 91, are supplied with DC 3.3V from the fixing relay board 115, and operate at this DC 3.3V. Meanwhile, temperature sensor TH2, which detects the temperature at the center of the heat roller 91, is supplied with DC 1.8V, and operates at this DC 1.8V. One reason for using temperature sensors TH1 to TH3 with different operating voltages in this way is that when the operation mode of the printer 1 transitions to the sleep mode, the supply of DC 3.3V is stopped, but the supply of DC 1.8V is maintained, so it is desirable to keep some temperature sensor TH2 operating even when the printer 1 transitions to the sleep mode.

[0095] As described above, the ASIC 101 of the main board 100 controls the heating temperature of the heater 93. For this reason, the signals THM1 to THM3 related to the temperatures detected by the temperature sensors TH1 to TH3, that is, the signals THM1 to THM3 detected in the fixing device 9, must be transmitted from the fixing device 9 to the main board 100. In this case, it is necessary to newly install a connection line connecting the main body connector 150 and the main board 100. However, since the main body connector 150 is disposed on the right side of the main body housing 2 and the main board 100 is disposed on the left side of the main body housing 2, the newly installed connection line must cross the main body frame 49 from side to side, similar to the first connection line CA1. However, there is little room in the main body housing 2 to install a similar connection line in addition to the first connection line CA1. Therefore, the first connection line CA1 is provided with a signal line for transmitting the signals THM1 to THM3 detected in the fixing device 9. As a result, by simply installing a short connection line, i.e., a second connection line CA2, connecting the main body connector 150 and the high-voltage power supply board 114 located near the main body connector 150, it becomes possible to transmit the signals THM1 to THM3 detected within the fixing device 9 to the main board 100.

[0096] 6, the signals THM1 to THM3 are transmitted to the main board 100 via the fixing relay board 115, the fixing connector 160, the main body connector 150, the second connection line CA2, the high-voltage power supply board 114, and the first connection line CA1. The ASIC 101 of the main board 100 controls the on / off timing of the 100V AC supplied to the heater 93 based on the signals THM1 to THM3 from the temperature sensors TH1 to TH3.

[0097] The AC-DC power supply board 112 is provided with a switching element 112E that turns on / off the AC 100V supplied to the heater 93, specifically, a circuit including a triac or the like. The ASIC 101 controls the switching element 112E to perform phase control and wave number control of the AC 100V and adjust the amount of power supplied to the heater 93. The AC-DC power supply board 112 is also provided with a relay 112D that turns on / off the input of AC 100V. The ASIC 101 outputs a relay on / off signal from an output port (not shown) to the AC-DC power supply board 112 to perform on / off control of the relay 112D. The on / off control of the relay 112D will be described later with reference to FIG. 8.

[0098] Hereinafter, the control process executed by the printer 1 configured as above will be described in detail with reference to FIG.

[0099] 8 shows the procedure of the print process executed by the ASIC 101. This print process starts when the printer 1 is turned on or when the printer 1 is in standby mode. In the following explanation of each process, steps are represented as "S".

[0100] 8, first, ASIC 101 outputs an OFF command to relay 112D and stops the switching operation of switching element 112E (S10). As a result, if relay 112D operates normally, relay 112D is turned OFF, and the application of AC voltage to heater 93 is cut off even if AC voltage supplied from inlet 200 is input to AC-DC power supply board 112 via connector 112A on the AC-DC power supply board 112 side. Also, if switching element 112E operates normally, application of AC voltage to heater 93 is similarly cut off.

[0101] Next, the ASIC 101 waits until a print command is received (S12: NO), and when a print command is received (S12: YES), the ASIC 101 determines whether the rear cover 12 is open (S14). This determination can be made based on the value of the rear cover open / close signal from the rear cover open / close detection switch 14. If the rear cover 12 is closed (S14: NO), the ASIC 101 performs normal printing to discharge the printed sheet S onto the discharge tray 22 (S40), and then ends the printing process.

[0102] On the other hand, when it is determined in S14 that the rear cover 12 is open (S14: YES), the ASIC 101 performs settings for straight discharge (S16). In straight discharge, as described above, an image is formed on the sheet S with the rear cover 12 open, and therefore the temperature control of the heater 93 of the fixing device 9 is different from that in normal printing, in which an image is formed on the sheet S with the rear cover 12 closed. For this reason, in the straight discharge setting, settings are made to perform temperature control for straight discharge.

[0103] Next, ASIC 101 outputs an ON command to relay 112D and starts the switching operation of switching element 112E (S18). Then, ASIC 101 judges whether or not fixing detection switch 15 is ON (S20). In this judgment, if fixing detection switch 15 is ON (S20: YES), that is, if fixing device 9 is attached to main body housing 2, CPU 39A repeats the judgment of S20 (S22: NO) until printing is completed, and when printing is completed (S22: YES), ASIC 101 ends the printing process.

[0104] On the other hand, if it is determined in S20 that the fixing detection switch 15 is in the OFF state (S20: NO), that is, if the fixing device 9 has been removed from the main body housing 2, the ASIC 101 outputs an OFF command to the relay 112D and stops the switching operation of the switching element 112E (S30) in the same manner as in S10. Then, the ASIC 101 stops printing (S32) and displays an abnormality on the display unit 29 (see FIG. 2), such as that the fixing device 9 has been removed during printing (S34), and then ends the printing process. In addition to the process of S34, the ASIC 101 may set the signal EN (see FIG. 7) to L and output it to the motor drive circuit MD.

[0105] As described above, the printer 1 of the present embodiment includes a main body housing 2 having a rear opening 2B, a rear cover 12 capable of opening and closing the rear opening 2B of the main body housing 2, a process unit 4 that forms a developer image on a sheet S, a fixing device 9 that fixes the developer image formed on the sheet S by the process unit 4, the fixing device 9 being removable from the rear opening 2B of the main body housing 2 with the rear cover 12 open, an AC-DC conversion circuit 112C that outputs power, a registration roller 35 that transports the sheet toward the process unit 4 and the fixing device 9, a main motor 106 that drives and rotates the registration roller 35, a motor drive circuit MD that receives power from the AC-DC conversion circuit 112C and rotates the main motor 106 based on the power, and a fixing presence / absence detection switch 15 that is in a first state when the fixing device 9 is attached to the main body housing 2 and is in a second state when the fixing device 9 is detached from the main body housing 2. The fixing presence / absence detection switch 15 is characterized in that, when in a first state, it enables the input of power from the AC-DC conversion circuit 112C to the motor drive circuit MD by connecting the AC-DC conversion circuit 112C and the motor drive circuit MD, and, when in a second state, it cuts off the input of power from the AC-DC conversion circuit 112C to the motor drive circuit MD by disconnecting the AC-DC conversion circuit 112C and the motor drive circuit MD.

[0106] Thus, the printer 1 of this embodiment includes the fixing presence / absence detection switch 15 that is turned on (first state) when the fixing device 9 is attached to the main body housing 2 and turned off (second state) when the fixing device 9 is removed from the main body housing 2, regardless of whether the rear cover 12 is opened or closed. Regardless of whether the rear cover 12 is opened or closed, when the fixing presence / absence detection switch 15 is in the first state, power can be input from the AC-DC conversion circuit 112C to the motor drive circuit MD. Therefore, even when the rear cover 12 of the printer 1 is open, the printer 1 can discharge the sheet S that is conveyed via the process unit 4 and the fixing device 9 to the rear cover 12. On the other hand, when the fixing device 9 is removed by the user with the rear cover 12 open, the printer 1 can cut off the input of power from the AC-DC conversion circuit 112C to the motor drive circuit MD by the fixing presence / absence detection switch 15.

[0107] Also, the fixing presence / absence detection switch 15 is characterized in that, when in the first state, it inputs power from the AC-DC conversion circuit 112C to the motor drive circuit MD.

[0108] As a result, power is actually input from the AC-DC conversion circuit 112C to the motor drive circuit MD, so that even when the rear cover 12 of the printer 1 is open, the printer 1 is able to eject the sheet S, which is transported via the process section 4 and the fixing device 9, to the rear cover 12.

[0109] The printer 1 further includes a high-voltage generation circuit 114C that supplies process power to the process unit 4 based on the power input from the AC-DC conversion circuit 112C, and the fixing presence / absence detection switch 15 is further characterized in that, in the first state, it enables the input of power from the AC-DC conversion circuit 112C to the high-voltage generation circuit 114C by connecting the AC-DC conversion circuit 112C and the high-voltage generation circuit 114C, and, in the second state, it blocks the input of power from the AC-DC conversion circuit 112C to the high-voltage generation circuit 114C by disconnecting the AC-DC conversion circuit 112C and the high-voltage generation circuit 114C.

[0110] As a result, regardless of whether the rear cover 12 is open or closed, when the fixing presence / absence detection switch 15 is in the first state, power can be input from the AC-DC conversion circuit 112C to the high voltage generation circuit 114C, so that even when the rear cover 12 of the printer 1 is open, the rear cover 12 can eject the sheet S conveyed via the process unit 4 and the fixing device 9 to the rear cover 12. On the other hand, when the rear cover 12 is open and the fixing device 9 is removed by the user, the printer 1 can use the fixing presence / absence detection switch 15 to cut off the input of power from the AC-DC conversion circuit 112C to the high voltage generation circuit 114C.

[0111] The printer 1 further includes an ASIC 101, and an on / off circuit 103 that switches whether or not the power generated by the AC-DC conversion circuit 112C is input to the high voltage generation circuit 114C, and the fixed / unfixed detection switch 15 inputs power to the on / off circuit 103 when in a first state and does not input power to the on / off circuit 103 when in a second state, and when power is input to the on / off circuit 103 by the fixed / unfixed detection switch 15, the on / off circuit 103 switches whether or not to input power from the AC-DC conversion circuit 112C to the high voltage generation circuit 114C depending on whether or not an instruction is given from the ASIC 101.

[0112] As a result, even when the fixing device 9 is attached to the main body housing 2, the on / off circuit 103 can switch whether or not to input power from the AC-DC conversion circuit 112C to the high voltage generation circuit 114C depending on whether or not an instruction is received from the ASIC 101.

[0113] The printer 1 further includes a main body connector 150, an AC-DC power supply board 112 having an AC-DC conversion circuit 112C and receiving AC power supplied from a commercial power source, and an inlet 200 receiving AC power from the commercial power source, and the fixing device 9 includes a heater 93 connected to the inlet 200 via a relay 112D, and a fixing connector connected to the main body connector 150 when the fixing device 9 is attached to the main body housing 2, and the AC-DC power supply board 112 supplies AC power to the heater 93 via the main body connector 150 and the fixing connector 160.

[0114] This allows the AC-DC power supply board 112 to supply AC power to the heater 93 via the main body connector 150 and the fixing connector 160.

[0115] The printer further includes a high-voltage power supply board 114 having a high-voltage generating circuit 114C and generating process power to be supplied to the process unit 4, the high-voltage power supply board 114 being arranged on one side of the main housing 2 so that the board surface and the one side are parallel to each other, and a main board 100 having an ASIC 101 being arranged on the other side opposite to the one side so that the board surface and the other side are parallel to each other, the main connector 150 being arranged on one side, and the fixed connector 160 being When the fixing device 9 is attached to the main housing 2, the main board 100 is arranged on one side, the main board 100 and the high-voltage power supply board 114 are connected by a first connection line CA1 arranged along the ceiling surface side or the bottom surface side within the main housing 2, the high-voltage power supply board 114 and the main connector 150 are connected by a second connection line CA2, and the main board 100 is connected to the fixing device 9 via the first connection line CA1, the high-voltage power supply board 114, the second connection line CA2, the main connector 150 and the fixing connector 160.

[0116] As a result, the main board 100 is connected to the fixing device 9 via the first connection line CA1, the high-voltage power supply board 114, the second connection line CA2, the main body connector 150, and the fixing connector 160, making it possible to omit the connection line connecting the main board 100 and the main body connector 150. As a result, the path of the connection line connecting the main board 100 and the main body connector 150 is no longer necessary, making it possible to reduce the size of the main body housing 2.

[0117] The printer 1 further includes an output tray 22 onto which the sheet S on which the developer image has been fixed by the fixing device 9 is output, and a cover sensor for detecting whether the rear cover 12 is open or closed. When the ASIC 101 receives a print command, if the fixing presence / absence detection switch 15 is in the first state and the rear cover open / close detection switch 14 detects that the rear cover 12 is closed, the ASIC 101 controls to execute normal output, in which the sheet S that has passed through the process unit 4 and the fixing device 9 is output onto the output tray 22 (S40 in FIG. 8). When the fixing presence / absence detection switch 15 is in the first state and the rear cover open / close detection switch 14 detects that the rear cover 12 is open, control is performed to execute straight discharge in which the sheet S that has passed through the process section 4 and the fixing device 9 is discharged to the rear cover 12 (YES in S20), and when the fixing presence / absence detection switch 15 switches from the first state to the second state while straight discharge is being executed, an instruction is given to the relay 112D to cut off the connection between the inlet 200 and the heater 93 (S30).

[0118] This makes it possible to interrupt straight ejection when the fixed state detection switch 15 switches from the first state to the second state while straight ejection is being performed.

[0119] The power line PL is for inputting the power generated by the AC-DC conversion circuit 112C to each of the motor driving circuit MD, the ASIC 101 and the on / off circuit 103, and extends via the fixing presence / absence detection switch 15. The power line PL branches off from the AC-DC conversion circuit 112C via the fixing presence / absence detection switch 15 at a first branch point BP1 on the downstream side and is connected to the motor driving circuit MD, branches off from the AC-DC conversion circuit 112C via the fixing presence / absence detection switch 15 at a second branch point BR2 on the downstream side and is connected to the ASIC 101, and is connected to the on / off circuit 103 at its terminal via the fixing presence / absence detection switch 15 from the AC-DC conversion circuit 112C.

[0120] This makes it possible for the motor drive circuit MD, the ASIC 101, and the on / off circuit 103 to share a single power line PL.

[0121] The fixing device 9 further has a gripping portion 142 to be gripped by a user, a lever 140 that can rotate between a first position and a second position around a lever shaft 140A, and a switch abutment portion 143 that can abut against the fixed / unfixed detection switch 15, and when the gripping portion 142 is not gripped, the lever 140 is in the first position and the fixed / unfixed detection switch 15 abuts against the fixed / unfixed detection switch 15 abutting portion, thereby entering the first state, and when the gripping portion 142 is gripped, the lever 140 rotates from the first position to the second position and the fixed / unfixed detection switch 15 abutting portion moves away, thereby entering the second state.

[0122] This makes it possible to use the fixing presence / absence detection switch 15 to accurately detect whether the fixing device 9 is attached to or detached from the main body housing 2.

[0123] Further, the rear cover 12 is characterized in that, when it is open, a sheet S that is transported via the process unit 4 and the fixing device 9 can be placed thereon.

[0124] This allows the sheet S to be discharged straight onto the rear cover 12.

[0125] As described above, the printer 1 of this embodiment includes a main housing 2, a rear cover 12 that can open and close the rear opening 2B of the main housing 2, a process unit 4 that forms a developer image on a sheet S, a fixing device 9 that fixes the developer image formed on the sheet S by the process unit 4 and is removable from the rear opening 2B of the main housing 2 with the rear cover 12 open, an AC-DC conversion circuit 112C that outputs power, a high-voltage generation circuit 114C that supplies process power to the process unit 4 based on the power input from the AC-DC conversion circuit 112C, and a fixing presence / absence detection switch 15 that is in a first state when the fixing device 9 is attached to the main housing 2 and is in a second state when the fixing device 9 is detached from the main housing 2. The fixing presence / absence detection switch 15 is characterized in that, when in a first state, it connects the AC-DC conversion circuit 112C and the high voltage generation circuit 114C, thereby allowing the input of power from the AC-DC conversion circuit 112C to the high voltage generation circuit 114C, and, when in a second state, it disconnects the AC-DC conversion circuit 112C and the high voltage generation circuit 114C, thereby cutting off the input of power from the AC-DC conversion circuit 112C to the high voltage generation circuit 114C.

[0126] In this manner, the printer 1 of the present embodiment includes the fixing presence / absence detection switch 15 that is turned on when the fixing device 9 is attached to the main body housing 2 and turned off when the fixing device 9 is removed from the main body housing 2, regardless of whether the rear cover 12 is open or closed. Regardless of whether the rear cover 12 is open or closed, when the fixing presence / absence detection switch 15 is in the first state, power can be input from the AC-DC conversion circuit 112C to the high voltage generation circuit 114C. Therefore, even when the rear cover 12 of the printer 1 is in an open state, the rear cover 12 can eject the sheet S conveyed via the process unit 4 and the fixing device 9 to the rear cover 12. On the other hand, when the fixing device 9 is removed by the user with the rear cover 12 open, the printer 1 can cut off the input of power from the AC-DC conversion circuit 112C to the high voltage generation circuit 114C by the fixing presence / absence detection switch 15.

[0127] The printer 1 further includes a control unit and an on / off circuit that switches whether or not the power generated by the AC-DC conversion circuit 112C is input to the high voltage generation circuit 114C, and the fixed / unfixed detection switch 15 inputs power to the on / off circuit 103 when in a first state and does not input power to the on / off circuit 103 when in a second state, and when power is input to the on / off circuit 103 by the fixed / unfixed detection switch 15, the on / off circuit 103 switches whether or not to input power from the AC-DC conversion circuit 112C to the high voltage generation circuit 114C depending on whether or not an instruction is received from the ASIC 101.

[0128] As a result, even when the fixing device 9 is attached to the main body housing 2, the on / off circuit 103 can switch whether or not to input power from the AC-DC conversion circuit 112C to the high voltage generation circuit 114C depending on whether or not an instruction is received from the ASIC 101.

[0129] The printer 1 further includes an AC-DC power supply board 112 having a main body connector and an AC-DC conversion circuit 112C and receiving AC power supplied from a commercial power source, and an input terminal receiving AC power supplied from the commercial power source. The fixing device 9 includes a heater 93 connected to the inlet 200 via a relay, and a fixing connector 160 that is connected to the main body connector 150 when the fixing device 9 is attached to the main body housing 2 and supplies AC power to the heater 93 via the relay 112D and the main body connector 150. The AC-DC power supply board 112 includes the AC-DC conversion circuit 112C and supplies AC power to the heater 93 via the main body connector 150 and the fixing connector 160. The ASIC 101 instructs the relay 112D to cut off the connection between the inlet 200 and the heater 93 when the fixing presence / absence detection switch 15 switches from the first state to the second state with the rear cover 12 open during the image forming operation.

[0130] This allows the AC-DC power supply board 112 to supply AC power to the heater 93 via the main body connector 150 and the fixing connector 160.

[0131] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0132] (1) In the above embodiment, a color laser printer 1 has been described as an example of an image forming apparatus, but the present invention is not limited to this and may be a monochrome laser printer. Also, the present invention is not limited to a printer and may be a multifunction machine or a copier.

[0133] (2) In the above embodiment, the "right side" is given as an example of one side of the main housing 2, but this is only because the right side is the side with sufficient space to place the main connector 150 and the fixed connector 160. In other words, if the side with sufficient space to place the main connector 150 and the fixed connector 160 is the left side, then one side of the main housing 2 can be the "left side."

[0134] (3) In the above embodiment, no mention is made of cutting off the power supply voltage supplied to a motor drive circuit (not shown) for driving the process motor 107. However, this may be done at the same timing as the motor drive circuit MD. [Explanation of symbols]

[0135] 1...color laser printer (image forming apparatus), 2...main body housing, 3...conveying section, 4...processing section, 5...exposure section, 9...fixing device, 12...rear cover (cover), 2B...rear opening (opening), 14...rear cover open / close detection switch (cover sensor), 15...fixing presence / absence detection switch (switch), 22...discharge tray, 31...supply tray, 35...registration roller (conveying roller), 61...photosensitive drum, 62...charger, 91...heating roller, 92...pressure section, 93...heater, 100...main board, 101...ASIC (control section), 102...DC-DC conversion circuit, 103...ON / OFF circuit, 104...detection circuit, 106...mechanism In-motor, 112...AC-DC power supply board (first power supply board), 112C...AC-DC conversion circuit (power output section), 112D...relay, 112E...switching element, 114...high voltage power supply board (second power supply board), 114C...high voltage generation circuit (process power supply section), 130...fixed handle, 140...lever, 140A...lever shaft, 141...main body, 142...grip, 143...switch abutment section, 200...inlet (input terminal), BP1...first branch point, BR2...second branch point, CA1 to CA5...first to fifth connection lines, MD...motor drive circuit, PL...power line, S...sheet, TH, TH1 to TH3...fixing temperature sensors.

Claims

1. a main body housing having an opening; a cover capable of opening and closing the opening of the main body housing; a process unit for forming a developer image on a sheet; a fixing device that fixes a developer image formed on the sheet by the process unit, the fixing device being removable from the opening of the main body housing with the cover open; a power output unit that outputs power; a conveying roller for conveying a sheet toward the processing unit and the fixing device; A motor that rotates the conveying roller; a motor drive circuit that receives the power from the power output unit and rotates the motor based on the power; a switch that is in a first state when the fixing device is attached to the main body housing and in a second state when the fixing device is detached from the main body housing; Equipped with The switch is When in the first state, the power output unit and the motor drive circuit are connected to each other, thereby enabling the input of power from the power output unit to the motor drive circuit, and when in the second state, the power output unit and the motor drive circuit are disconnected to each other, thereby blocking the input of power from the power output unit to the motor drive circuit.

1. An image forming apparatus comprising:

2. The switch is 2. The image forming apparatus according to claim 1, wherein the power is input from the power output section to the motor drive circuit when the image forming apparatus is in the first state.

3. Furthermore, a process power supply unit that supplies process power to the process unit based on the power input from the power output unit, The switch further comprises: When in the first state, the power output unit and the process power supply unit are connected to each other, thereby enabling the input of the power from the power output unit to the process power supply unit; and cutting off the input of power from the power output unit to the process power supply unit by disconnecting the power output unit from the process power supply unit when the power output unit is in the second state.

3. The image forming apparatus according to claim 2,

4. Furthermore, A control unit; an on / off circuit for switching whether or not the power output from the power output unit is input to the process power supply unit; Equipped with The switch is When the power supply is in the first state, the power is input to the on-off circuit, and when the power supply is in the second state, the power is not input to the on-off circuit; The on / off circuit is when the power is being input to the on / off circuit by the switch, switching is performed as to whether or not the power is to be input from the power output unit to the process power supply unit depending on the presence or absence of an instruction from the control unit.

4. The image forming apparatus according to claim 3.

5. Furthermore, The main connector, a first power supply board having the power output unit and receiving AC power supplied from a commercial power supply; an input terminal to which the AC power is input from a commercial power source; Equipped with The fixing device is a heater connected to the input terminal via a relay; a fixing connector that is connected to the main body connector when the fixing device is attached to the main body housing, The first power supply board includes: supplying the AC power to the heater via the main body connector and the fixing connector; 5. The image forming apparatus according to claim 4.

6. a second power supply board having the process power supply unit and generating the process power to be supplied to the process unit, the second power supply board being disposed on one side surface of the main body housing such that a board surface and the one side surface are parallel to each other; A main board having the control unit, the main board being disposed on the other side surface opposite to the one side surface such that the board surface and the other side surface are parallel to each other; Further equipped with The main body connector is disposed on the one side surface side, the fixing connector is disposed on the one side surface side when the fixing device is attached to the main body housing, the main board and the second power supply board are connected by a first connection line arranged along a ceiling surface side or a bottom surface side of the main body housing, the second power supply board and the main body connector are connected by a second connection line; the main board is connected to the fixing device via the first connection line, the second power board, the second connection line, the main body connector, and the fixing connector; 6. The image forming apparatus according to claim 5,

7. Furthermore, an output tray to which the sheet on which the developer image has been fixed by the fixing device is output; a cover sensor for detecting whether the cover is open or closed; Equipped with The control unit is when a print command is received, if the switch is in the first state and the cover sensor detects that the cover is closed, control is performed to execute normal discharge, in which the sheet that has passed through the process unit and the fixing device is discharged onto the discharge tray; when a print command is received, if the switch is in the first state and the cover sensor detects that the cover is open, control is performed to execute straight discharge, in which the sheet that has passed through the process unit and the fixing device is discharged to the cover; when the switch is switched from the first state to the second state during the straight discharge, an instruction is given to the relay to cut off the connection between the input terminal and the heater.

6. The image forming apparatus according to claim 5,

8. a power line for inputting the power generated by the power output unit to each of the motor drive circuit, the control unit, and the on / off circuit, the power line extending via the switch; The power line is a first branch point located downstream from the power output unit via the switch and connected to the motor drive circuit; the power output unit is branched at a second branch point downstream via the switch and connected to the control unit; A terminal connected from the power output unit through the switch is connected to the on / off circuit.

5. The image forming apparatus according to claim 4.

9. The fixing device further comprises: a lever having a grip portion to be gripped by a user and rotatable about a lever axis between a first position and a second position; A switch contact portion capable of contacting the switch; having The switch is When the gripping portion is not gripped, the lever is in the first position and the switch abutment portion abuts against the lever to enter the first state. When the gripping portion is gripped, the lever rotates from the first position to the second position, and the switch abutment portion is released, thereby entering the second state.

2. The image forming apparatus according to claim 1,

10. the cover is capable of supporting the sheet to be transported through the process unit and the fixing device when the cover is open.

2. The image forming apparatus according to claim 1,

11. a main body housing having an opening; a cover capable of opening and closing the opening of the main body housing; a process unit for forming a developer image on a sheet; a fixing device that fixes a developer image formed on the sheet by the process unit, the fixing device being removable from the opening of the main body housing with the cover open; a power output unit that outputs power; a process power supply unit that supplies process power to the process unit based on the power input from the power output unit; a switch that is in a first state when the fixing device is attached to the main body housing and in a second state when the fixing device is detached from the main body housing; Equipped with The switch is When in the first state, the power output unit and the process power supply unit are connected to each other, thereby enabling the input of power from the power output unit to the process power supply unit, and when in the second state, the power output unit and the process power supply unit are disconnected to each other, thereby cutting off the input of power from the power output unit to the process power supply unit.

1. An image forming apparatus comprising:

12. Furthermore, A control unit; an on / off circuit for switching whether or not the power output from the power output unit is input to the process power supply unit; Equipped with The switch is When the power supply is in the first state, the power is input to the on-off circuit, and when the power supply is in the second state, the power is not input to the on-off circuit; The on / off circuit is when the power is being input to the on / off circuit by the switch, switching is performed as to whether or not the power is to be input from the power output unit to the process power supply unit depending on the presence or absence of an instruction from the control unit.

12. The image forming apparatus according to claim 11.

13. Furthermore, The main connector, a first power supply board having the power output unit and receiving AC power supplied from a commercial power supply; an input terminal to which the AC power supplied from a commercial power source is input; Equipped with The fixing device is a heater connected to the input terminal via a relay; a fuser connector that is connected to the main body connector when the fuser device is attached to the main body housing and that supplies the AC power to the heater via the relay and the main body connector; The first power supply board includes: the power output unit supplies the AC power to the heater via the main body connector and the fixing connector; The control unit is when the switch is switched from the first state to the second state with the cover open during an image forming operation, an instruction is given to the relay to cut off a connection between the input terminal and the heater.

13. The image forming apparatus according to claim 12.

14. a second power supply board having the process power supply unit and generating the process power to be supplied to the process unit, the second power supply board being disposed on one side surface of the main body housing such that a board surface and the one side surface are parallel to each other; A main board having the control unit, the main board being disposed on the other side surface opposite to the one side surface such that the board surface and the other side surface are parallel to each other; Further equipped with The main body connector is disposed on the one side surface side, the fixing connector is disposed on the one side surface side when the fixing device is attached to the main body housing, the main board and the second power supply board are connected by a first connection line arranged along a ceiling surface side or a bottom surface side of the main body housing, the second power supply board and the main body connector are connected by a second connection line; the main board is connected to the fixing device via the first connection line, the second power board, the second connection line, the main body connector, and the fixing connector; 14. The image forming apparatus according to claim 13.

15. Furthermore, an output tray to which the sheet on which the developer image has been fixed by the fixing device is output; a cover sensor for detecting whether the cover is open or closed; Equipped with The control unit is when a print command is received, if the switch is in the first state and the cover sensor detects that the cover is closed, control is performed to execute normal discharge, in which the sheet that has passed through the process unit and the fixing device is discharged onto the discharge tray; when a print command is received, if the switch is in the first state and the cover sensor detects that the cover is open, control is performed to execute straight discharge, in which the sheet that has passed through the process unit and the fixing device is discharged to the cover; when the switch is switched from the first state to the second state during the straight discharge, an instruction is given to the relay to cut off the connection between the input terminal and the heater.

14. The image forming apparatus according to claim 13.

16. The fixing device further comprises: a lever having a grip portion to be gripped by a user and rotatable about a lever axis between a first position and a second position; A switch contact portion capable of contacting the switch; having The switch is When the gripping portion is not gripped, the lever is in the first position and the switch abutment portion abuts against the lever to enter the first state. When the gripping portion is gripped, the lever rotates from the first position to the second position, and the switch abutment portion is released, thereby entering the second state.

12. The image forming apparatus according to claim 11.

17. the cover is capable of supporting the sheet to be transported through the process unit and the fixing device when the cover is open.

12. The image forming apparatus according to claim 11.

Images