Image forming apparatus

Abstract

To provide an image forming apparatus capable of saving power and suppressing heat generation compared with a conventional one.SOLUTION: The first discharge path 201A for discharging the sheet S to the outside of the main body without passing through the cutter position and the second discharge path 201B for discharging the sheet S to the outside of the main body via the cutter position are provided as a part of the conveyance path, and the flapper solenoid 89 that switches the flapper 88 to either the first state in which the sheet S is guided to the first discharge path 201A or the second state in which the sheet S is guided to the second discharge path 201B is a self-holding solenoid. The flapper solenoid 89 further includes a flapper switching circuit 119 capable of switching the direction and energization state of a current flowing through one end T1 and the other end T2 of the coil 90 of the flapper solenoid 89.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus equipped with a cutter that cuts a sheet. [Background technology]

[0002] 2. Description of the Related Art Conventionally, as an image forming apparatus for printing an image on a sheet, which is a printing object, an image forming apparatus equipped with a cutter for cutting the sheet on which the image has been formed is known.

[0003] For example, Japanese Patent Application Laid-Open No. 2023-19469 discloses that after an image is formed on a sheet, a pair of discharge rollers arranged downstream in the sheet conveyance direction rotates forward to discharge the sheet toward a cutting device, and the sheet is conveyed to a cutting position and stopped there, and the stopped sheet is cut by a cutting blade extending in the sheet width direction that intersects with the conveyance direction.Then, the cut sheet is discharged by the pair of discharge rollers to a discharge tray and stacked. Here, the image forming apparatus described in the above patent document only has one discharge path provided with a cutting device as a discharge path for discharging sheets after an image has been formed on them. However, since there is no need to cut sheets when performing normal printing on commonly used standard-sized sheets, it is also possible to provide a discharge path that does not pass through the cutting device in addition to the discharge path that passes through the cutting device in order to accommodate such normal printing. An image forming apparatus having multiple discharge paths further requires a flapper for switching between discharge paths, a self-holding solenoid for switching the state of the flapper, and a flapper switching circuit for passing current through the coil of the self-holding solenoid. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-19469 Summary of the Invention [Problem to be solved by the invention]

[0005] The control unit of the image forming device uses a flapper switching circuit to change the direction of current flowing through the coil of the self-holding solenoid and switch the flapper. However, changing the direction of current flowing through the coil of the self-holding solenoid requires connecting the control unit and the flapper switching circuit via at least four terminals. In addition to the flapper switching circuit, the control unit of the image forming device also needs to control the image forming unit and the cutter motor driver for driving the cutter, which results in an insufficient number of terminals in the control unit.

[0006] The present invention has been made to solve the problems of the prior art, and aims to provide an image forming apparatus having two input terminals, a first input terminal and a second input terminal, and a flapper switching circuit that can switch the state of a flapper using a self-holding solenoid. [Means for solving the problem]

[0007] In order to achieve the above object, the image forming apparatus according to the present application includes an image forming unit that forms a developer image on a sheet, a heating rotor that heats the sheet, and a pressure rotor that nips the sheet between the heating rotor and the fixing unit, and that fixes the developer image formed on the sheet, a cutter that is disposed at a cutter position downstream of the fixing unit in a sheet conveyance direction in a conveyance path along which the sheet is conveyed after passing through the image forming unit and the fixing unit, and that cuts the sheet on which the developer image has been fixed, a cutter motor that drives the cutter, a motor driver that controls the drive of the cutter motor, an apparatus main body that has the conveyance path, and that has a first discharge path that is part of the conveyance path and that discharges the sheet outside the apparatus main body without passing through the cutter position, and a second discharge path that passes through the cutter position and that discharges the sheet outside the apparatus main body, and a flatbed that guides the sheet to either one of the first discharge path and the second discharge path. a self-holding solenoid having a flapper, a coil, and switching the flapper between a first state in which the sheet is guided to the first discharge path and a second state in which the sheet is guided to the second discharge path depending on the direction of current flowing through one end and the other end of the coil; a flapper switching circuit capable of switching the direction of current flowing through one end and the other end of the coil and the energized state; and a control unit electrically connected to the image forming unit, the fixing unit, the motor driver, and the flapper switching circuit, respectively; the flapper switching circuit has a first input terminal, a second input terminal, a first output terminal, and a second output terminal, the first output terminal is connected to one end of the coil, the second output terminal is connected to the other end of the coil, and the first input terminal and the second input terminal are respectively connected to the control unit, and the direction of current flowing through one end and the other end of the coil and the energized state can be switched by control signals input from the control unit to the first input terminal and the second input terminal. [Effects of the Invention]

[0008] In the image forming apparatus according to the present application having the above configuration, when the control unit controls the image forming unit, the motor driver, and the flapper switching circuit, the control unit needs terminals for connecting to the image forming unit, the motor driver, and the flapper switching circuit, respectively. The flapper switching circuit has the feature of being able to switch the state of the flapper using two input terminals, a first input terminal and a second input terminal. Therefore, while four terminals are normally required to switch the flapper, because switching can be performed using the first input terminal and the second input terminal, the number of terminals in the control unit can be reduced. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram illustrating the configuration of an MFP according to a first embodiment. [Figure 2] FIG. 2 is a perspective view showing a schematic configuration of a cutter provided in the MFP. [Figure 3] FIG. 2 is a block diagram showing the control configuration of the MFP. [Figure 4] 3 is a diagram showing the electrical configuration of a flapper switching circuit provided on a main board in the first embodiment. FIG. [Figure 5] 10A and 10B are diagrams illustrating patterns of control signals transmitted from an ASIC. [Figure 6] 10 is a diagram illustrating the current flowing through the coil of the flapper solenoid in the first pattern. FIG. [Figure 7] FIG. 2 is a diagram illustrating a flapper solenoid in an initial state. [Figure 8] 10A and 10B are diagrams illustrating a flapper solenoid that performs a suction operation. [Figure 9] 10 is a diagram illustrating the current flowing through the coil of the flapper solenoid in the third pattern. FIG. [Figure 10] 10A and 10B are diagrams illustrating a flapper solenoid that performs a return operation. [Figure 11] 10 is a flowchart showing the procedure of a sheet single-sided printing cutting process. [Figure 12]10 is a flowchart showing a detailed procedure for a flapper switching process, particularly for switching from a first position to a second position. [Figure 13] 10 is a flowchart showing a detailed procedure for a flapper switching process, particularly for switching from the second position to the first position. [Figure 14] 10 is a flowchart showing the procedure of a sheet double-sided printing cutting process. [Figure 15] FIG. 10 is a diagram showing the electrical configuration of a flapper switching circuit provided on a main board in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, first and second embodiments in which an image forming apparatus according to the present application is embodied in an MFP (Multi Function Peripheral, also called a multifunction peripheral) will be described with reference to the drawings.

[0011] First Embodiment First, the overall configuration of the MFP 1 according to the first embodiment will be described. Fig. 1 shows a schematic configuration of the MFP 1 according to the first embodiment. In the following description, the front-rear and up-down directions are as shown on the paper.

[0012] [Overall configuration of MFP] 1 is a cross-sectional view showing a schematic configuration of an MFP1 according to the first embodiment. The MFP1 is an example of an image forming device and has a print function, a copy function, a scan function, etc. The MFP1 may also have a fax function in addition to these functions.

[0013] The MFP 1 includes an image forming main body unit 2 and an image reading unit 9. The image forming main body unit 2 is an electrophotographic type and has a function of forming an image on a sheet S. The image forming main body unit 2 has a function of forming a monochrome image on a sheet S, but the present disclosure is not limited to this, and the image forming main body unit 2 may have a function of forming a full-color image on a sheet S, for example.

[0014] The image reading unit 9 reads an image formed on a medium such as paper, and includes an image reading sensor such as a CCD (Charge Coupled Device) type or a CIS (Contact Image Sensor) type, and a movement mechanism for moving the image reading sensor. The image reading unit 9 reads the image formed on the medium under the control of the ASIC 105 (see FIG. 3).

[0015] The image forming main body 2 includes an apparatus main body 20, a conveying mechanism 3, a process unit 4, a fixing unit 6, and a cutter 10. The process unit 4 corresponds to an example of an "image forming unit." Note that hereinafter, the apparatus main body 20 may also be simply referred to as the "main body 20."

[0016] The main body 20 is formed in a substantially rectangular parallelepiped shape and has a front cover 21, a supply tray 31, a discharge tray 22, a conveying path 201, and a re-conveying path 202. The front cover 21 is attached to the front of the main body 20 in an openable and closable manner. The supply tray 31 is attached to the bottom of the main body 20 in a detachable manner. A sheet S is placed on the supply tray 31. The sheet S is a standard size sheet such as A4 size. The sheet S is, for example, a paper medium such as plain paper or cardboard, but is not limited to these, and may also be an OHP film. The discharge tray 22 is provided on the top of the main body 20, and the sheet S on which a developer image has been formed is placed on the discharge tray 22.

[0017] The conveying path 201 is a path for conveying the sheet S placed on the supply tray 31 in a conveying direction toward the discharge tray 22 via the process unit 4, and includes a first path 201C, a first discharge path 201A, and a second discharge path 201B. The first path 201C is a path through which the sheet S passes through the process unit 4 and the fixing unit 6. The conveying path 201 branches into the first discharge path 201A and the second discharge path 201B from a branch position D1, which is the downstream end position of the first path 201C.

[0018] The first discharge path 201A is a path for discharging the sheet S from the branch position D1 to the outside of the apparatus body 20 without passing through the cutter position SP where the cutter 10 is arranged. The second discharge path 201B is a path for discharging the sheet S from the branch position D1 to the outside of the apparatus body 20 via the cutter position SP. Therefore, the sheet S conveyed via the process unit 4 and the fixing unit 6 is either discharged to the discharge tray 22 via the first discharge path 201A or discharged to the discharge tray 22 via the second discharge path 201B.

[0019] The discharge path of the sheet S is switched between the first discharge path 201A and the second discharge path 201B by a flapper 88. Specifically, the discharge path is switched by switching the position of the flapper 88 between a first position 88A and a second position 88B. More specifically, the first position 88A is a position where the sheet S conveyed by the conveying rollers 36 is guided to the first discharge path 201A. The state where the flapper 88 is at the first position 88A is also referred to as a first state. In the first state where the flapper 88 is at the first position 88A, the sheet S is guided to the first discharge path 201A. On the other hand, the second position 88B is a position where the sheet S conveyed by the conveying rollers 36 is guided to the second discharge path 201B. The state where the flapper 88 is at the second position 88B is also referred to as a second state. In a second state in which the flapper 88 is at the second position 88B, the sheet S is guided to a second discharge path 201B. The position of the flapper 88 is switched via a cam mechanism using a flapper solenoid 89 as a drive source, as described below, and when printing on a standard-sized sheet S that does not require cutting, the flapper 88 is set to the first position 88A and the sheet S is discharged. On the other hand, when printing requires cutting of the sheet S, the flapper 88 is set to the second position 88B and the sheet S is discharged. However, even when cutting is performed, in double-sided printing, the flapper 88 is set to the first position 88A during the first single-sided printing. Details of the operation of the flapper 88 will be described later.

[0020] The re-conveying path 202 is a path for conveying the sheet S, one side of which has a developer image formed thereon, in the opposite direction to the conveying direction and conveying it again toward the process unit 4, i.e., for conveying the sheet S, one side of which has been printed, back to the process unit 4 when double-sided printing is performed. The re-conveying path 202 is a path that starts from a connection position D2 on the second discharge path 201B, which is downstream in the conveying direction from the branching position D1, and ends at a junction position J on the conveying path 201, which is upstream in the conveying direction of the pre-registration sensor SE1. Note that the connection position D2, which is the start point of the re-conveying path 202, may be any position downstream of the fixing unit.

[0021] The conveying mechanism 3 includes a pickup roller 33, a separation roller 34, a registration roller 35, a conveying roller 36, a first discharge roller 87, a second discharge roller 86, a third discharge roller 85, a flapper 88, re-conveying rollers 38 and 39, a main motor 108 (see Figure 3), and a discharge motor 109 (see Figure 3).

[0022] The pickup roller 33 picks up the sheets S in the supply tray 31 that have been pushed upward by the sheet pressure plate 32, and transports them toward the transport path 201. The separation roller 34 separates the sheets S picked up by the pickup roller 33 one by one.

[0023] The registration rollers 35 are disposed upstream of the process unit 4 on the conveying path 201. The registration rollers 35 align the direction of the leading edge of the sheet S, and then convey the sheet S toward the process unit 4. In the following description, the leading edge of the sheet S means the leading edge of the sheet S in the conveying direction, and the trailing edge of the sheet S means the trailing edge of the sheet S in the conveying direction. The conveying rollers 36 convey the sheet S after it has passed through the fixing unit 6 toward the first discharge rollers 87 or the third discharge rollers 85.

[0024] The third discharge roller 85 and the second discharge roller 86 are disposed on the second discharge path 201B. The third discharge roller 85 is disposed at a position upstream of the cutter position SP where the cutter 10 is disposed, and the second discharge roller 86 is disposed at a position downstream of the cutter position SP.

[0025] The third discharge roller 85 is rotated by the driving force from the discharge motor 109 (see FIG. 3). A third driven roller 85A is disposed at a position opposite the third discharge roller 85 across the second discharge path 201B. The third driven roller 85A is rotated in accordance with the rotation of the third discharge roller 85. The second discharge roller 86 is also rotated by the driving force from the discharge motor 109. A second driven roller 86A is disposed at a position opposite the second discharge roller 86 across the second discharge path 201B. The second driven roller 86A is rotated in accordance with the rotation of the second discharge roller 86.

[0026] The third discharge roller 85 and the second discharge roller 86 rotate to transport the sheet S in the transport direction, thereby discharging the sheet S onto the discharge tray 22. The rotation to transport the sheet S in the transport direction corresponds to a counterclockwise rotation when viewed from the left side, with the left-right direction of the main body 20 as an axis.

[0027] On the other hand, the first discharge roller 87 is disposed on the first discharge path 201A. The first discharge roller 87 is rotated by a driving force from a discharge motor 109 (see FIG. 3). A first driven roller 87A is disposed at a position facing the first discharge roller 87 across the first discharge path 201A. The first driven roller 87A is rotated in accordance with the rotation of the first discharge roller 87. The first discharge roller 87 rotates to transport the sheet S in the transport direction, thereby discharging the sheet S onto the discharge tray 22. The first discharge roller 87 also rotates in a direction opposite to the rotation that transports the sheet S in the transport direction, thereby transporting the sheet S to the re-conveyance path 202. The rotation in the direction opposite to the rotation that transports the sheet S in the transport direction corresponds to a clockwise rotation when viewed from the left side, with the left-right direction of the main body 20 as an axis.

[0028] Re-conveying rollers 38 and 39 are arranged on the re-conveying path 202. The re-conveying rollers 38 and 39 convey the sheet S conveyed to the re-conveying path 202 toward the process unit 4. The re-conveying rollers 38 and 39 re-convey the sheet S, on one side of which an image has been formed, toward the process unit 4 via the re-conveying path 202, thereby making it possible to form images on both sides of the sheet S.

[0029] The process unit 4 forms an image on the sheet S and is housed within the main body 20. The image is a developer image. The process unit 4 has a drum cartridge 5 and a laser unit 7. The drum cartridge 5 has a photosensitive drum 51, a toner storage unit 57, a supply roller 56, a developing roller 55, a charger 52, a transfer roller 53, and a pinch roller 54. The drum cartridge 5 can be removed from the main body 20 by opening the front cover 21. The pinch roller 54 of the drum cartridge 5 faces the registration roller 35. The pinch roller 54 rotates following the rotation of the registration roller 35 and transports the sheet S together with the registration roller 35.

[0030] The photosensitive drum 51 is rotated by a driving force from a main motor 108 (see FIG. 3) to transport the sheet S in the transport direction, thereby transporting the sheet S in the transport direction. The photosensitive drum 51 rotates clockwise when viewed from the left, with the left-right direction of the main body 20 as its axis. Toner is stored in the toner storage section 57. The supply roller 56 supplies the toner in the toner storage section 57 to the developing roller 55. The charger 52 is a scorotron type charger, and uniformly charges the surface of the photosensitive drum 51. The charger 52 may be a charging roller.

[0031] A transfer roller 53 is disposed at a position facing the photosensitive drum 51. The transfer roller 53 forms a transfer nip TN between itself and the photosensitive drum 51 on the transport path 201. Note that a transfer belt may be used instead of the transfer roller 53.

[0032] The main body 20 has a laser unit 7 at an upper portion inside thereof. The laser unit 7 has a polygon mirror 131 (see FIG. 3), a laser emission unit 132 (see FIG. 3), a polygon motor 133 (see FIG. 3), a lens, a reflecting mirror, and the like (not shown). The laser unit 7 exposes the surface of the photosensitive drum 51 by scanning the surface of the photosensitive drum 51 at high speed with a laser beam based on image data emitted from the laser emission unit 132. The two-dot chain line in FIG. 1 indicates the laser beam emitted from the laser emission unit 132.

[0033] An electrostatic latent image based on image data is formed on the surface of the photosensitive drum 51 by exposing it to light with the laser unit 7. The developing roller 55 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 51, thereby forming a toner image on the surface of the photosensitive drum 51.

[0034] A transfer voltage is applied to the transfer roller 53. The transfer roller 53 transports the sheet S between itself and the photosensitive drum 51, thereby transferring the toner image formed on the surface of the photosensitive drum 51 onto the sheet S passing through the transfer nip TN. In this way, an image is formed on the sheet S.

[0035] The fixing unit 6 is disposed downstream of the process unit 4 on the conveying path 201. The fixing unit 6 includes a heating roller 61, a pressure roller 62, and a heater 63. The heating roller 61 is an example of a heating rotator and heats the sheet S. The pressure roller 62 is an example of a pressure rotator and forms a nip N between the heating roller 61 and the pressure roller 62 to pressurize the sheet S. The fixing unit 6 corresponds to an example of a "fixing unit." The pressure roller 62 rotates by the driving force of the main motor 108 to convey the sheet S in the conveying direction. The pressure roller 62 rotates counterclockwise as viewed from the left side, with the left-right direction of the main body 20 as its axis to convey the sheet S in the conveying direction. The heater 63 is, for example, a halogen heater and heats the heating roller 61.

[0036] The fixing device 6 heats the sheet S with the heating roller 61 and rotates the pressure roller 62, thereby conveying the sheet S while applying pressure with the heating roller 61 and the pressure roller 62, thereby fixing the developer image formed on the sheet S by the process unit 4 to the sheet S.

[0037] Although the fixing device 6 has been described as including the heating roller 61, the pressure roller 62, and the heater 63, the invention is not limited to this. For example, the fixing device 6 may have a configuration including the heater 63, a nip plate that receives radiant heat from the heater 63, a heating belt that rotates around the nip plate, and a pressure roller.

[0038] The fixing unit 6 may also have a substrate on which a heat generating pattern is formed, a belt that rotates around the substrate, and a pressure roller, with the substrate and belt contacting the pressure roller.The fixing unit 6 may also have a heating roller, a heater, and a pressure belt.

[0039] A cutter 10 is disposed between the third discharge roller 85 and the second discharge roller 86 in the second discharge path 201B. The cutter 10 is disposed downstream of the fixing unit 6 in the conveyance direction of the sheet S. The MFP 1 stops the rotation of the third discharge roller 85 and the second discharge roller 86 so that the cutting position on the sheet S reaches the cutter position SP. With the rotation of the third discharge roller 85 and the second discharge roller 86 stopped, the MFP 1 cuts the sheet S using the cutter 10.

[0040] FIG. 2 shows a schematic configuration of the cutter 10. As shown in FIG. 2, the cutter 10 has a cutter frame 11, a slide rail 12, a fixed blade 13, a sheet passing section 14, a moving blade 15, a slide holder 16, and a cutter motor 106. The cutter frame 11 extends in the axial direction. The slide rail 12 is a rail formed on the cutter frame 11 and extending in the axial direction. The fixed blade 13 is a flat blade fixed to the cutter frame 11 and extending in the axial direction. The sheet passing section 14 is a space formed in the cutter frame 11 through which the sheet S passes. In this embodiment, the sheet passing section 14 is formed between the slide rail 12 and the fixed blade 13. The moving blade 15 is a disc-shaped blade and is rotatably supported by the slide holder 16.

[0041] The slide holder 16 engages with the slide rail 12 and is attached to the cutter frame 11 so as to be slidable along the slide rail 12. When the cutter motor 106 is driven in the forward direction, the slide holder 16 slides from one side to the other in the axial direction. When the cutter motor 106 is driven in the reverse direction, the slide holder 16 slides from the other side to one side in the axial direction. The slide holder 16 is movable from an initial position FP indicated by a solid line in FIG. 2 to a completion position KP indicated by a dashed line. The slide holder 16, to which the moving blade 15 is fixed, is movable at the cutter position SP in a cutting direction intersecting with the conveyance direction of the sheet S. That is, the cutter 10 can cut the sheet S in a direction intersecting with the conveyance direction of the sheet S. The cutting direction is a direction from the initial position FP toward the completion position KP or a direction from the completion position KP toward the initial position FP.

[0042] When the sheet S is at the cutter position SP and the slide holder 16 moves along the slide rail 12 to the completion position KP, the single sheet S is sandwiched between the fixed blade 13 and the movable blade 15 and cut into two pieces. After the sheet S is cut, the MFP 1 rotates the third discharge roller 85 and the second discharge roller 86 for a predetermined time, thereby discharging the two cut sheets S onto the discharge tray 22.

[0043] The MFP 1 is configured to be able to cut A4 and letter-sized sheets S at the center of the sheet in the conveying direction by the cutter 10. In other words, the length of the conveying path 201 from the nip N to the cutter position SP in FIG. 1 is designed to be longer than half (148.5 mm) of the dimension (297 mm) of an A4-sized sheet S in the conveying direction.

[0044] With this configuration, when an A4-sized or letter-sized sheet S is cut at cutter position SP with the rotation of the third discharge roller 85 and the second discharge roller 86 stopped, the trailing edge of the sheet S passes through the nip N of the fuser 6. When the rotation of the third discharge roller 85 and the second discharge roller 86 is stopped to cut the sheet S at cutter position SP with the sheet S sandwiched in the nip N of the fuser 6, the rotation of the pressure roller 62 must be stopped. However, if the rotation of the pressure roller 62 stops with the sheet S sandwiched in the nip N of the fuser 6, heat is applied locally from the heating roller 61 to the same location on the sheet S. Therefore, when the rotation of the third discharge roller 85 and the second discharge roller 86 is stopped and the sheet S is cut at cutter position SP, the trailing edge of the sheet S must pass through the nip N of the fuser 6.

[0045] Furthermore, the length of the conveying path 201 from the nip of the conveying roller 36 to the cutter position SP in FIG. 1 is designed to be longer than half (148.5 mm) of the dimension (297 mm) of an A4 size sheet S in the conveying direction.

[0046] With this configuration, when the sheet S is cut at the cutter position SP with the rotation of the third discharge roller 85 and the second discharge roller 86 stopped, the trailing edge of the sheet S passes through the nip of the conveyance roller 36. If the nip N of the conveyance roller 36 and the pressure roller 62 is rotating while the sheet S is pinched when the sheet S is cut at the cutter position SP with the rotation of the third discharge roller 85 and the second discharge roller 86 stopped, the sheet S may bend like an accordion between the third discharge roller 85 and the conveyance roller 36. Therefore, with the above configuration, it is possible to stop the sheet S at the cutter position SP without the sheet S bending like an accordion by simply stopping the rotation of the third discharge roller 85 and the second discharge roller 86 without stopping the rotation of the conveyance roller 36 or the fixing unit 6.

[0047] The length of the first discharge path 201A is designed to be shorter than the length of the second discharge path 201B. This is to quickly discharge the sheet S outside the apparatus main body 20 when the sheet S after image formation is not cut. The second discharge roller 86 is positioned forward in the front-to-rear direction than the first discharge roller 87. This makes it possible to ensure a space for separating the cutter position SP from the fixing unit 6. Furthermore, since the short cut sheet S discharged from the second discharge roller 86 can be discharged further forward, the user can more easily access the discharged sheet S.

[0048] The distance between the third discharge roller 85 and the second discharge roller 86 is designed to be shorter (139.7 mm) than half the dimension (279.4 mm) of a letter-sized sheet S in the conveying direction. This is to enable the sheet S after being cut by the cutter 10 to be conveyed between the third discharge roller 85 and the second discharge roller 86. Conversely, a cutting instruction is not accepted for a sheet S whose length is less than twice the distance between the third discharge roller 85 and the second discharge roller 86.

[0049] [MFP1 electrical configuration] Next, the electrical configuration of the MFP 1 will be described with reference to Fig. 3. Fig. 7 shows the electrical configuration of the MFP 1. Note that Fig. 3 mainly describes components necessary for explaining the first embodiment, and omits other components of the MFP 1.

[0050] 3, the MFP 1 is provided with multiple boards, including a main board 100 and a low-voltage power supply board 110. The boards are connected to each other via harnesses. Although not shown, there are also main motor boards, high-voltage power supply boards, and the like.

[0051] The low-voltage power supply board 110 has an AC-DC conversion circuit, and inputs an AC voltage supplied by a commercial power source, for example, AC 100 V, and converts this AC 100 V to a DC voltage, for example, DC 24 V, using the AC-DC conversion circuit. The low-voltage power supply board 110 outputs the generated DC 24 V to the main board 100 via a harness.

[0052] The main board 100 has a DC-DC conversion circuit that converts DC 24V from the low-voltage power supply board 110 to, for example, DC 3.3V by the DC-DC conversion circuit. 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 other DC voltage values, for example, DC 5V, multiple DC-DC conversion circuits may be provided to generate DC 1.8V, DC 5V, etc. in addition to DC 3.3V.

[0053] The DC-DC conversion circuit of the main board 100 inputs DC 24V from the low-voltage power supply board 110 to the flapper switching circuit 119 , and the flapper switching circuit 119 supplies it to the flapper solenoid 89 based on a signal from the ASIC 105 .

[0054] The main board 100 also includes an ASIC 105, a ROM 102, a RAM 103, an NVRAM 104, motor drivers 115 to 118 for driving various motors, and a flapper switching circuit 119 for switching the direction and energization state of the current flowing through the flapper solenoid 89. Also connected to the main board 100 are a pre-register sensor SE1, a post-register sensor SE2, a discharge sensor SE3, a sheet sensor SE4, an operation panel PA, a communication interface (I / F) 130, the flapper solenoid 89, and various motors.

[0055] ASIC 105 is equipped with CPU 101. CPU 101 performs overall control of each unit of MFP 1. CPU 101 and ASIC 105 correspond to an example of a "control unit." In the following description, CPU 101 will be described as an operating entity as an example of a control unit, but the operating entity may be replaced by ASIC 105 as a whole, or CPU 101 and ASIC 105 may cooperate to perform each operation. ASIC 105 is electrically connected to ROM 102, RAM 103, NVRAM 104, pre-registration sensor SE1, post-registration sensor SE2, discharge sensor SE3, sheet sensor SE4, operation panel PA, communication I / F 130, fuser 6, and laser unit 7.

[0056] The ROM 102 stores various control programs and various settings for controlling the MFP 1. The control programs include a sheet single-sided printing and cutting process (FIG. 11) and a sheet double-sided printing and cutting process (FIG. 14), which will be described later.

[0057] The RAM 103 is used as a work area from which various control programs are read and as a storage area for temporarily storing image data included in a job. The CPU 101 controls each part of the MFP 1 in accordance with the control programs read from the ROM 102 and signals output from various sensors, while storing the processing results in the RAM 103 or the NVRAM 104.

[0058] The operation panel PA has, for example, a touch panel in which a touchpad and a display are integrally formed, and a key button section. The operation panel PA accepts user operations and outputs the accepted information to the ASIC 105. For example, the user can operate the operation panel PA to configure various settings related to the MFP 1. The user can also issue instructions for executing the copy function and scan function.

[0059] The main motor 108 outputs a driving force to the pickup roller 33, the registration roller 35, the conveyance roller 36, the re-conveyance rollers 38 and 39, the pressure roller 62, and the drum cartridge 5. When the main motor 108 is driven in the forward direction, the output of the main motor 108 transmits a driving force to the conveyance roller 36, the pressure roller 62, the photosensitive drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35. Then, the conveyance roller 36, the pressure roller 62, the photosensitive drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35 rotate to convey the sheet S in the conveyance direction.

[0060] On the other hand, even if the main motor 108 is driven in the reverse direction, the driving force is not transmitted to the conveying roller 36, the pressure roller 62, the drum cartridge 5, the pickup roller 33, and the registration roller 35.

[0061] Furthermore, the CPU 101 drives the main motor 108 in the forward direction via the motor driver 116, thereby transmitting a driving force to the re-conveying rollers 38 and 39. The transmitted driving force causes the re-conveying rollers 38 and 39 to rotate so as to convey the sheet S toward the process unit 4. The rotation of the re-conveying rollers 38 and 39 to convey the sheet S toward the process unit 4 is a clockwise rotation when viewed from the left side, with the left-right direction of the main body 20 as an axis.

[0062] On the other hand, even when the CPU 101 drives the main motor 108 in the reverse direction, the driving force is transmitted to the re-conveying rollers 38 and 39. The transmitted driving force causes the re-conveying rollers 38 and 39 to rotate so as to convey the sheet S toward the process unit 4.

[0063] The discharge motor 109 transmits driving force to the first discharge roller 87, the second discharge roller 86, and the third discharge roller 85. The CPU 101 drives the discharge motor 109 to rotate in the forward direction via a stepping motor driver 117. By driving the discharge motor 109 to rotate in the forward direction, the first discharge roller 87, the second discharge roller 86, and the third discharge roller 85 rotate to transport the sheet S in the transport direction. The rotation of the first discharge roller 87, the second discharge roller 86, and the third discharge roller 85 to transport the sheet S in the transport direction is counterclockwise when viewed from the left side, with the left-right direction of the main body 20 as an axis.

[0064] As a result, the sheet S is discharged onto the discharge tray 22 via the first discharge path 201A or the second discharge path 201B. Meanwhile, the CPU 101 drives the discharge motor 109 in the reverse direction. The first discharge rollers 87 rotate in the direction opposite to the conveying direction of the sheet S. For the first discharge rollers 87, the rotation in the direction opposite to the conveying direction of the sheet S means clockwise rotation as viewed from the left side, with the left-right direction of the main body 20 as an axis. As a result, the sheet S being conveyed along the first discharge path 201A is conveyed in the direction opposite to the conveying direction, and the sheet S is conveyed toward the re-conveyance path 202.

[0065] The CPU 101 controls the drive of the cutter motor 106 via a DC motor driver 118. The cutter motor 106 is a DC brush motor. The cutter motor 106 is not limited to a DC brush motor and may be a DC brushless motor. When the cutter motor 106 is driven in the forward direction, the slide holder 16 moves the moving blade 15 in the width direction of the sheet S, thereby cutting the sheet S. The encoder 113 is attached to the rotation shaft of the cutter motor 106 and outputs a signal corresponding to the rotation of the cutter motor 106. The CPU 101 receives the signal output from the encoder 113 and acquires the rotation direction, rotation position, and rotation speed of the cutter motor 106 based on the received signal. This allows the CPU 101 to know the position of the slide holder 16 on the slide rail 12, i.e., the position of the moving blade 15 in the axial direction.

[0066] The CPU 101 controls the flapper 88 via a flapper switching circuit 119. Specifically, the ASIC 105 and the flapper switching circuit 119 are connected by two signal lines, and a control signal of either on (=H) or off (=L) is input to the flapper switching circuit 119 from an output port of the ASIC 105 depending on the current state of the MFP 1. The flapper switching circuit 119 then controls the on / off of an internal semiconductor transistor based on the input control signal, switching the direction of current flowing through the flapper solenoid 89 and whether it is energized or not. This switches the position of the flapper 88 between a first position 88A and a second position 88B. The first position 88A is a position where the sheet S conveyed by the conveyance roller 36 is guided to the first discharge path 201A. The first position 88A is also a position where the sheet S on the first discharge path 201A is guided to the re-conveyance path 202. The second position 88B is a position where the sheet S conveyed by the conveying roller 36 is guided to the second discharge path 201B. The semiconductor transistors include bipolar transistors and field effect transistors. Details of the operation of the flapper switching circuit 119 and the flapper solenoid 89 will be described later.

[0067] The pre-registration sensor SE1 is disposed upstream of the registration rollers 35 on the conveying path 201 (see FIG. 1), and is a sensor that detects the passage of the sheet S. The pre-registration sensor SE1 may be a sensor having an actuator that oscillates when the sheet S comes into contact with it, or an optical sensor. The pre-registration sensor SE1 outputs an ON signal when the sheet S is passing, and outputs an OFF signal when the sheet S is not passing. The detection signal by the pre-registration sensor SE1 is output to the ASIC 105.

[0068] The post-registration sensor SE2 is disposed upstream of the fixing unit 6 on the conveying path 201, specifically between the registration roller 35 and the transfer roller 53 (see FIG. 1), and is a sensor that detects the passage of the sheet S. The post-registration sensor SE2 has the same configuration as the pre-registration sensor SE1. A detection signal by the post-registration sensor SE2 is output to the ASIC 105.

[0069] The discharge sensor SE3 is disposed between the fixing unit 6 and the conveying roller 36 on the conveying path 201 (see FIG. 1), and detects the passage of the sheet S. The discharge sensor SE3 has the same configuration as the pre-registration sensor SE1. A detection signal from the discharge sensor SE3 is output to the ASIC 105.

[0070] The sheet sensor SE4 is disposed between the cutter position SP and the second discharge roller 86 (see FIG. 1) and detects the passage of the sheet S. The sheet sensor SE4 has the same configuration as the pre-registration sensor SE1. A detection signal from the sheet sensor SE4 is output to the ASIC 105. Note that the distance in the conveying direction from the sheet sensor SE4 to the nip N is greater than the distance in the conveying direction from the discharge sensor SE3 to the nip N.

[0071] The communication I / F 130 is connected to a network such as a LAN, and enables connection to an external device such as a PC incorporating a driver for the MFP 1. The CPU 101 can receive a print job via the communication I / F 130. The print job includes various information required to form an image on the sheet S, such as image data for image formation, the size and type of the sheet S to be used for image formation, and information on whether or not to cut the sheet S.

[0072] [Electrical configuration of the flapper switching circuit] Next, the electrical configuration of the aforementioned MFP1 will be described in more detail, particularly the electrical configuration of flapper switching circuit 119 provided on main board 100, using Fig. 4. Fig. 4 particularly shows only flapper switching circuit 119 provided on main board 100 and the electrical configuration of MFP1 related thereto.

[0073] 4, the flapper switching circuit 119 according to the first embodiment includes six semiconductor transistors: a first NPN transistor Q1, a first PNP transistor Q2, a second NPN transistor Q3, a third NPN transistor Q4, a second PNP transistor Q5, and a fourth NPN transistor Q6, as well as a first resistor R11, a second resistor R12, a third resistor R21, and a fourth resistor R22. On the other hand, as input / output terminals, the flapper switching circuit 119 includes a first input terminal IN1 for receiving a control signal output from an output port P1 of the ASIC 105, a second input terminal IN2 for receiving a control signal output from an output port P2 of the ASIC 105, a first output terminal OUT1 connected to one end T1 of a coil 90 included in the flapper solenoid 89, and a second output terminal OUT2 connected to the other end T2 of the coil 90 included in the flapper solenoid 89. The flapper switching circuit 119 is also provided with DC 24V generated in the low voltage power supply board 110 as a power source.

[0074] In addition, the first NPN transistor Q1 corresponds to the "first semiconductor transistor," the first PNP transistor Q2 corresponds to the "second semiconductor transistor," the second NPN transistor Q3 corresponds to the "third semiconductor transistor," the third NPN transistor Q4 corresponds to the "fourth semiconductor transistor," the second PNP transistor Q5 corresponds to the "fifth semiconductor transistor," and the fourth NPN transistor Q6 corresponds to the "sixth semiconductor transistor."

[0075] Among the semiconductor transistors included in the flapper switching circuit 119, the first NPN transistor Q1 has a base connected to the first input terminal IN1 via a first resistor R11, an emitter connected to ground GND, and a collector connected to the base of the first PNP transistor Q2. The first PNP transistor Q2 has a collector connected to the first output terminal OUT1 and an emitter connected to a 24V DC power supply. The second NPN transistor Q3 has a base connected to the first input terminal IN1 via a second resistor R12, an emitter connected to ground GND, and a collector connected to a connection point CP2 between the second PNP transistor Q5 and the second output terminal OUT2. The third NPN transistor Q4 has a base connected to the second input terminal IN2 via a third resistor R21, an emitter connected to ground GND, and a collector connected to the base of the second PNP transistor Q5. The second PNP transistor Q5 has a collector connected to the second output terminal OUT2 and an emitter connected to a DC 24 V power supply. The fourth NPN transistor Q6 has a base connected to the second input terminal IN2 via a fourth resistor R22, an emitter connected to ground GND, and a collector connected to a connection point CP1 between the first PNP transistor Q2 and the first output terminal OUT1.

[0076] In the flapper switching circuit 119 of the first embodiment, in order to reduce the number of terminals of the ASIC 105 and the flapper switching circuit 119, the signal line between the base of the first NPN transistor Q1 and the input terminal of the flapper switching circuit 119 and the signal line between the base of the second NPN transistor Q3 and the input terminal of the flapper switching circuit 119 are combined into a single common signal line. Similarly, the signal line between the base of the third NPN transistor Q4 and the input terminal of the flapper switching circuit 119 and the signal line between the base of the fourth NPN transistor Q6 and the input terminal of the flapper switching circuit 119 are combined into a single common signal line. In addition, by performing control using the following control signals, the number of signal lines between the ASIC 105 and the flapper switching circuit 119 can be reduced to two, and the direction of the current flowing through the flapper solenoid 89 and whether it is energized or not can be switched.

[0077] Specifically, either an on (=H) or off (=L) control signal is input from output port P1 and output port P2 of ASIC 105 to flapper switching circuit 119. Specifically, the combinations of control signals input from each output port are the three patterns shown in FIG.

[0078] First, the first pattern is a signal combination for switching the position of flapper 88 from position 88A, which is the first position, to position 88B, which is the second position. In the first pattern, an off (=L) control signal is input from output port P1 to first input terminal IN1. With the off control signal, the input voltage is 0V, and current to first input terminal IN1 is cut off. Meanwhile, an on (=H) control signal is input from output port P2 to second input terminal IN2. With the on control signal, a current of, for example, 3.3V is input to second input terminal IN2. In the first pattern, no current flows from the base to the emitter of first NPN transistor Q1, turning first NPN transistor Q1 off; that is, no current flows between the collector and emitter. Similarly, no current flows from the base to the emitter of second NPN transistor Q3, turning second NPN transistor Q3 off; that is, no current flows between the collector and emitter. Furthermore, the absence of current flowing from the collector to the emitter of the first NPN transistor Q1 means that no current flows from the 24V DC power supply connected to the emitter of the first PNP transistor Q2 to the ground GND on the emitter side of the first NPN transistor Q1. In other words, no current flows from the emitter to the base of the first PNP transistor Q2. This means that the first PNP transistor Q2 is off, meaning that no current flows between the emitter and collector. Furthermore, current flows from the base to the emitter of the third NPN transistor Q4, turning the third NPN transistor Q4 on, meaning that current flows between the collector and emitter. Similarly, current flows from the base to the emitter of the fourth NPN transistor Q6, turning the fourth NPN transistor Q6 on, meaning that current flows between the collector and emitter. Furthermore, the fact that current flows from the collector to the emitter of the third NPN transistor Q4 means that current flows from the 24V DC power supply connected to the emitter side of the second PNP transistor Q5 to the ground GND on the emitter side of the third NPN transistor Q4. In other words, current also flows from the emitter to the base of the second PNP transistor Q5, turning on the second PNP transistor Q5, i.e., current flows between the emitter and collector.

[0079] As a result, in the first pattern, current flows from the other end T2 to one end T1 of the coil 90 provided in the flapper solenoid 89 as shown in FIG.

[0080] Here, the flapper solenoid 89, which serves as the driving source for the flapper 88, is a self-holding solenoid. As shown in FIG. 7, the flapper solenoid 89 basically includes a plunger 150, a permanent magnet 151, a coil 90, and a spring 152. The plunger 150 is a movable iron core made of a magnetic material that moves linearly in the axial direction (up and down in FIG. 7) by the flapper solenoid 89, and is connected to the flapper 88 by a cam mechanism (not shown). As described below, the position of the flapper 88 can be switched between a first position and a second position as the plunger 150 moves axially. Furthermore, as shown in FIG. 7, the permanent magnet 151 is disposed coaxially with the coil 90 around the plunger 150. It may be a single cylindrical magnet, or multiple magnets may be disposed to form a cylindrical shape as a whole. The permanent magnet 151 has magnetic poles formed such that the inner side is a north pole and the outer side is a south pole. On the other hand, the spring 152 is connected to one end of the plunger 150 and biases the plunger 150 in one direction (upward in FIG. 7) by the spring force.

[0081] In the flapper solenoid 89 having the above configuration, when no current flows through the coil 90 immediately after the MFP 1 is powered on, the plunger 150 is biased by the spring 152 in the opposite direction (upward in FIG. 7) to the magnetic field generated by the permanent magnet 151, and the flapper solenoid 89 is fixed in the initial state position as shown in FIG. 7. The initial state position is hereinafter referred to as the initial position. When the plunger 150 is in the initial position, the flapper 88 is located at the first position 88A, and is in the first state in which the flapper 88 guides the sheet to the first discharge path 201A.

[0082] In the first pattern described above, when a current flows from the other end T2 to the one end T1 of the coil 90 of the flapper solenoid 89 as shown in FIG. 6, the coil 90 generates a magnetic field in the same direction as the magnetic field generated by the permanent magnet 151 as shown in FIG. 8. The magnetic field generated by the coil 90 attracts the plunger 150, which is a magnetic body, toward the generated magnetic field and moves from the initial position to the attraction position. When the plunger 150 of the flapper solenoid 89 is in the attraction position, the flapper 88 is in the second position 88B, and is in a second state in which the plunger 150 guides the sheet to the second discharge path 201B. Even if the power supply to the coil 90 is immediately cut off after the plunger 150 has moved to the attraction position, the magnetic force of the permanent magnet can continue to hold the plunger 150 in the attraction position.

[0083] Here, the second pattern is a signal combination for holding the plunger 150 in the attraction position after it has moved, as shown in FIG. 8 , i.e., for holding the flapper 88 at the second position 88B. In the second pattern, an OFF (=L) control signal is input from the output port P1 to the first input terminal IN1. With the OFF control signal, the input voltage is 0V, and current to the first input terminal IN1 is cut off. Meanwhile, an OFF (=L) control signal is also input from the output port P2 to the second input terminal IN2. With the OFF control signal, the input voltage is 0V, and current to the second input terminal IN2 is cut off. In the second pattern, no current flows from the base to the emitter of the first NPN transistor Q1, turning the first NPN transistor Q1 off. In other words, no current flows between the collector and emitter. Similarly, no current flows from the base to the emitter of the second NPN transistor Q3, turning the second NPN transistor Q3 off. In other words, no current flows between the collector and emitter. Furthermore, the absence of current flowing from the collector to the emitter of the first NPN transistor Q1 means that no current flows from the 24V DC power supply connected to the emitter of the first PNP transistor Q2 to the ground GND on the emitter side of the first NPN transistor Q1. In other words, no current flows from the emitter to the base of the first PNP transistor Q2, so the first PNP transistor Q2 is off, meaning no current flows between the emitter and collector. Similarly, no current flows from the base to the emitter of the third NPN transistor Q4, so the third NPN transistor Q4 is off, meaning no current flows between the collector and emitter. Similarly, no current flows from the base to the emitter of the fourth NPN transistor Q6, so the fourth NPN transistor Q6 is off, meaning no current flows between the collector and emitter. Furthermore, the fact that no current flows from the collector to the emitter of the third NPN transistor Q4 means that no current flows from the 24V DC power supply connected to the emitter side of the second PNP transistor Q5 to the ground GND on the emitter side of the third NPN transistor Q4, that is, no current flows from the emitter to the base of the second PNP transistor Q5, and the second PNP transistor Q5 is turned off, that is, no current flows between the emitter and collector.

[0084] As a result, in the second pattern, the current to the coil 90 of the flapper solenoid 89 is cut off. Even if no current flows through the coil 90, the plunger 150, which has moved to the attraction position, is held in that position by the permanent magnet 151. That is, the flapper 88 also remains at the second position 88B, and the second state in which the sheet is guided to the second discharge path 201B continues.

[0085] On the other hand, the third pattern is the opposite of the first pattern, and is a signal combination for switching the position of flapper 88 from the second position, 88B, to the first position, 88A. In the third pattern, an ON (=H) control signal is input from output port P1 to first input terminal IN1. With the ON control signal, a current of, for example, 3.3V is input to first input terminal IN1. Meanwhile, an OFF (=L) control signal is input from output port P2 to second input terminal IN2. With the OFF control signal, the input voltage becomes 0V, and current to second input terminal IN2 is cut off. In the third pattern, current flows from the base to the emitter of first NPN transistor Q1, turning on first NPN transistor Q1; that is, current flows between the collector and emitter. Similarly, current flows from the base to the emitter of second NPN transistor Q3; that is, second NPN transistor Q3 is turned on; that is, current flows between the collector and emitter. Furthermore, current flowing from the collector to the emitter of the first NPN transistor Q1 means that current flows from the 24V DC power supply connected to the emitter of the first PNP transistor Q2 to the ground GND on the emitter side of the first NPN transistor Q1. In other words, current also flows from the emitter to the base of the first PNP transistor Q2, turning the first PNP transistor Q2 on, i.e., current flows between the emitter and collector. Furthermore, current does not flow from the base to the emitter of the third NPN transistor Q4, turning the third NPN transistor Q4 off, i.e., no current flows between the collector and emitter. Similarly, current does not flow from the base to the emitter of the fourth NPN transistor Q6, turning the fourth NPN transistor Q6 off, i.e., no current flows between the collector and emitter. Furthermore, the fact that no current flows from the collector to the emitter of the third NPN transistor Q4 means that no current flows from the 24V DC power supply connected to the emitter side of the second PNP transistor Q5 to the ground GND on the emitter side of the third NPN transistor Q4, that is, no current flows from the emitter to the base of the second PNP transistor Q5, and the second PNP transistor Q5 is turned off, that is, no current flows between the emitter and collector.

[0086] As a result, in the third pattern, as shown in FIG. 9, a current flows from one end T1 to the other end T2 of the coil 90 provided in the flapper solenoid 89.

[0087] When a current flows from one end T1 to the other end T2 of the coil 90, the coil 90 generates a magnetic field in the opposite direction to the magnetic field generated by the permanent magnet 151, as shown in FIG. 10. The magnetic field generated by the coil 90 cancels out the magnetic field generated by the permanent magnet 151. The magnetic fields generated by the coil 90 and the permanent magnet 151 are designed to be approximately the same. Then, the plunger 150 returns to its initial position due to the restoring force of the spring 152. Because the plunger 150 of the flapper solenoid 89 returns to its initial position, the flapper 88 is positioned at the first position 88A, and the flapper 88 is in the first state in which it guides the sheet S to the first discharge path 201A.

[0088] Even if the power supply to the coil 90 is immediately cut off after the plunger 150 has moved to the initial position, the magnetic force of the permanent magnet can continue to hold the plunger 150 at the initial position. That is, by sending a control signal in the second pattern after the plunger 150 has moved to the initial position, the plunger 150 is held in that position by the permanent magnet 151 even if no current flows through the coil 90. That is, the flapper 88 also continues to be located at the first position 88A, and the first state in which the sheet is guided to the first discharge path 201A continues.

[0089] As described above, the flapper switching circuit 119 can switch the direction of current flowing through the flapper solenoid 89 and whether or not current is being applied by combining control signals sent from the ASIC 105, thereby switching the position of the flapper 88 between position 88A, which is the first position, and position 88B, which is the second position. In particular, in the first embodiment, the flapper solenoid 89 is a self-holding solenoid, so there is no need to continue to pass current in order to maintain the plunger 150 in the initial position and the attraction position, which makes it possible to suppress heat generation in the coil and reduce power consumption.

[0090] [Control processing by the control unit] Next, among the various control processes executed by the ASIC 105 of the MFP 1 having the above configuration, a single-sided sheet printing and cutting process will be described with reference to Fig. 11. Fig. 11 is a flowchart illustrating a main process executed after the power of the MFP 1 is turned on, particularly a printing process in which single-sided printing and the printed sheet S are cut by the cutter 10. This process is executed when a printing process in which single-sided printing and the printed sheet S are cut by the cutter 10 is received from an external device such as a PC via the communication I / F 130. Note that each process shown in the flowchart in Fig. 11 below is stored in a memory provided in the MFP 1 and executed by the ASIC 105. The ASIC 105 is an example of a control unit.

[0091] First, in step (hereinafter abbreviated as S) 1, the ASIC 105 turns on the heater 63 and controls the heater 63 so that the heating roller 61 reaches a target temperature.

[0092] Next, in S2, the ASIC 105 drives the main motor 108 to rotate in the forward direction. When the main motor 108 is driven in the forward direction, a driving force is transmitted by the output of the main motor 108 to the conveying roller 36, the pressure roller 62, the photosensitive drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35 (FIG. 3). Then, the conveying roller 36, the pressure roller 62, the photosensitive drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35 rotate to convey the sheet S in the conveying direction.

[0093] Thereafter, in S3, the ASIC 105 performs a flapper switching process (FIG. 12) to be described later. In the flapper switching process in S3, the flapper 88 is switched from the first position 88A to the second position 88B, as will be described later.

[0094] As described above, immediately after the MFP 1 is powered on and before the execution of the printing process begins, the flapper 88 is in the first position 88A as its initial position. By the process of S3, the flapper 88 is switched from the first position 88A to the second position 88B. Thereby, the flapper 88 thereafter guides the sheet S conveyed by the conveyance roller 36 to the second discharge path 201B on which the cutter 10 is provided.

[0095] Next, in S4, the ASIC 105 executes image formation processing. Specifically, in the image formation processing, the sheet S in the supply tray 31 is first picked up and transported toward the transport path 201. After the post-registration sensor SE2 detects the leading edge of the sheet S, image formation on the sheet S begins. Image data to be printed is received along with a print instruction from an external device, such as a PC, via the communication I / F 130. The surface of the photosensitive drum 51 is exposed to light by the laser unit 7, forming an electrostatic latent image based on the image data. The developing roller 55 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 51, thereby forming a toner image on the surface of the photosensitive drum 51. The transfer roller 53 then transports the sheet S between itself and the photosensitive drum 51, transferring the toner image formed on the surface of the photosensitive drum 51 to the sheet S passing through the transfer nip TN. In this manner, image formation on the sheet S is completed. The developer image formed on the sheet S by the process unit 4 is then fixed to the sheet S using the fixing device 6. Then, when the discharge sensor SE3 detects the leading edge of the sheet S that has passed between the heating roller 61 and the pressure roller 62 of the fixing unit 6, the discharge motor 109 is driven to rotate forward, and the sheet S on the second discharge path 201B is conveyed in the conveying direction. Then, when it is determined that the discharge sensor SE3 has switched off, the image forming process ends.

[0096] Then, in S5, the ASIC 105 executes the sheet cutting process following the image formation process (S4). In the sheet cutting process, the ASIC 105 first waits until the sheet S, which is being conveyed along the second discharge path 201B by the third discharge roller 85 and the second discharge roller 86, reaches a sheet stop position. For example, when cutting the sheet S at the center in the conveyance direction, the sheet stop position is the position where the center of the sheet S reaches the cutter position SP of the cutter 10. The ASIC 105 determines whether the sheet S has reached the sheet stop position by counting the number of steps of the discharge motor 109 when the leading edge of the sheet S is detected by the sheet sensor SE4. Specifically, the ASIC 105 stops the discharge motor 109 when the amount of rotation of the discharge motor 109 from the time the leading edge of the sheet S is detected by the sheet sensor SE4 reaches a first predetermined amount. Here, the "first predetermined amount" is a value determined based on information about the length of the sheet S in the conveyance direction. Hereinafter, this length information will also be referred to simply as "sheet size information." Specifically, the sheet size information is information such as "A4 size" or "letter size." The sheet size information can be acquired by reading it from the information set as the paper size by the print job. When the sheet S reaches the sheet stop position, the ASIC 105 temporarily stops the drive of the discharge motor 109 and drives the cutter motor 106 in the forward direction to move the slide holder 16 from the initial position FP toward the completion position KP. As a result, the cutter motor 106 slides the slide holder 16 from one side to the other in the axial direction, so that the slide holder 16 starts moving from the initial position FP indicated by the solid line in FIG. 2 toward the completion position KP indicated by the dashed line. As the slide holder 16 moves with the sheet S sandwiched between the movable blade 15 and the fixed blade 13 supported by the slide holder 16, the sheet S is cut in the axial direction. The ASIC 105 then waits until the slide holder 16 reaches the completion position KP and then stops the cutter motor 106. This completes the cutting of the sheet S by the cutter 10.

[0097] Furthermore, after cutting of the sheet S is completed, the discharge motor 109 is driven in the forward direction again, and as the discharge motor 109 is driven in the forward direction, the third discharge roller 85 and the second discharge roller 86 rotate, and the sheet S cut by the cutter 10 is transported toward the discharge tray 22 by the third discharge roller 85 and the second discharge roller 86.

[0098] Then, in S6, the ASIC 105 determines whether the job being executed includes printing of a next sheet. If the determination is that a next sheet is to be printed (S6: YES), the cutter 10 is returned to the initial position FP (S7). More specifically, the ASIC 105 reversely drives the cutter motor 106 to move the slide holder 16 from the completion position KP toward the initial position FP, and stops the cutter motor 106 when the cutter 10 reaches the initial position FP. The CPU 101 then returns the process to S4 and continues executing the processes from S4 onward. Here, when the sheet single-sided printing and cutting process is to be continued on the next sheet S, switching control of the flapper 88 is not performed. This is because the flapper 88 has already been switched to the second position 88B in the process of S3 and is maintained in that state. Therefore, when consecutively printing and cutting, it is not necessary to switch the flapper 88 each time.

[0099] On the other hand, if there is no next sheet to be printed (S6: NO), the process proceeds to S8.

[0100] In S8, the ASIC 105 performs a flapper switching process (FIG. 13) to be described later. In the flapper switching process in S8, the flapper 88 is switched from the second position 88B to the first position 88A, as described later. As a result, the flapper 88 thereafter guides the sheet S conveyed by the conveying roller 36 to the first discharge path 201A where the cutter 10 is not provided.

[0101] Next, in S9, the ASIC 105 drives the cutter motor 106 in the reverse direction to move the slide holder 16 from the completion position KP toward the initial position FP. Then, similar to S7 above, the ASIC 105 waits until the slide holder 16 reaches the initial position FP, and stops the cutter motor 106 when the slide holder 16 reaches the initial position FP (S10).

[0102] Next, in S11, the ASIC 105 turns off the heater 63 and stops the main motor 108 (S12), and then ends the sheet single-sided printing and cutting process.

[0103] The order of the processes in S8 to S12 may be reversed. Also, when printing of the final sheet is completed and an instruction for the next job has been issued, the heater 63 may not be turned off in S11, and the next job may be executed while the main motor 108 is rotating forward.

[0104] Next, the flapper switching process for switching the flapper 88 of S3 from the first position 88A to the second position 88B will be described with reference to Fig. 12. Fig. 12 is a flowchart of the flapper switching process for switching the flapper 88 from the first position 88A to the second position 88B.

[0105] First, in S21, the ASIC 105 outputs an OFF (=L) control signal from the output port P1 to the first input terminal IN1, and outputs an ON (=H) control signal from the output port P2 to the second input terminal IN2. As a result, a current flows from the other end T2 to one end T1 of the coil 90 provided in the flapper solenoid 89, as shown in FIG.

[0106] When a current flows from the other end T2 to the one end T1 of the coil 90, the plunger 150, which is a magnetic body, is attracted to the generated magnetic field and moves from the initial position to the attraction position, as shown in Fig. 8. Accordingly, the flapper 88 moves from the first position 88A to the second position 88B, and enters the second state in which the flapper 88 guides the sheet to the second discharge path 201B.

[0107] Thereafter, in S22, ASIC 105 determines whether a predetermined time has elapsed since the control signal was output in S21. The predetermined time is the time required for plunger 150 to move to the suction position after the control signal is output, i.e., the time required for flapper 88 to move to second position 88B, and is set to an extremely short time, for example, 100 ms.

[0108] Then, when it is determined that a predetermined time has elapsed since the ASIC 105 output the control signal in S21 (S22: YES), the ASIC 105 outputs an OFF (=L) control signal from the output port P1 to the first input terminal IN1, and outputs an OFF (=L) control signal from the output port P2 to the second input terminal IN2 (S23). As a result, the current to the coil 90 provided in the flapper solenoid 89 is cut off. As described above, even if no current flows through the coil 90, the plunger 150, which has moved to the attraction position, is held in that position by the permanent magnet 151. That is, the flapper 88 also remains at the second position 88B, and the second state in which the sheet is guided to the second discharge path 201B continues until a new control signal is sent in S31.

[0109] Next, the flapper switching process for switching the flapper 88 from the second position 88B to the first position 88A in S8 will be described with reference to Fig. 13. Fig. 13 is a flowchart of the flapper switching process for switching the flapper 88 from the second position 88B to the first position 88A.

[0110] First, in S31, the ASIC 105 outputs an ON (=H) control signal from the output port P1 to the first input terminal IN1, and outputs an OFF (=L) control signal from the output port P2 to the second input terminal IN2. As a result, a current flows from one end T1 to the other end T2 of the coil 90 provided in the flapper solenoid 89, as shown in FIG.

[0111] 10, when a current flows from one end T1 to the other end T2 of the coil 90, the magnetic field of the permanent magnet 151 is demagnetized, and the flapper 88 moves from the attraction position to the initial position due to the bias of the spring 152. Accordingly, the flapper 88 moves from the second position 88B to the first position 88A, and enters the first state in which the flapper 88 guides the sheet to the first discharge path 201A.

[0112] Thereafter, in S32, the ASIC 105 determines whether a predetermined time has elapsed since the control signal was output in S31. The predetermined time is the time required for the plunger 150 to move to its initial position after the control signal is output, i.e., the time required for the flapper 88 to move to the first position 88A, and is set to an extremely short time, for example, 100 ms.

[0113] Then, when it is determined that a predetermined time has elapsed since the ASIC 105 output the control signal in S31 (S32: YES), the ASIC 105 outputs an OFF (=L) control signal from the output port P1 to the first input terminal IN1, and outputs an OFF (=L) control signal from the output port P2 to the second input terminal IN2 (S33). As a result, the current to the coil 90 provided in the flapper solenoid 89 is cut off. As described above, even if no current flows through the coil 90, the plunger 150, which has moved to its initial position, is maintained in that position by the permanent magnet 151. That is, the flapper 88 also remains in the first position 88A, and the first state in which the sheet is guided to the first discharge path 201A continues until a new control signal is sent in S21.

[0114] Next, among the various control processes executed by the ASIC 105 of the MFP 1 having the above configuration, a sheet duplex printing and cutting process will be described with reference to Fig. 14. Fig. 14 is a flowchart illustrating a main process executed after the MFP 1 is powered on, particularly a printing process in which double-sided printing is performed and the printed sheet S is cut by the cutter 10. This process is executed when a printing process in which double-sided printing and the printed sheet S is cut by the cutter 10 is received from an external device such as a PC via the communication I / F 130. Note that each process shown in the flowchart in Fig. 14 below is stored in a memory provided in the MFP 1 and is executed by the ASIC 105.

[0115] First, in S41, the ASIC 105 turns on the heater 63 and controls the heater 63 so that the heating roller 61 reaches the target temperature.

[0116] Next, in S42, the ASIC 105 drives the main motor 108 to rotate in the forward direction. When the main motor 108 is driven in the forward direction, a driving force is transmitted by the output of the main motor 108 to the conveying roller 36, the pressure roller 62, the photosensitive drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35 (FIG. 3). Then, the conveying roller 36, the pressure roller 62, the photosensitive drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35 rotate to convey the sheet S in the conveying direction.

[0117] Next, in S43, the ASIC 105 executes image formation processing on the first side of the sheet S. Specifically, in the image formation processing, the sheet S is first picked up from the supply tray 31 and transported toward the transport path 201. After the post-registration sensor SE2 detects the leading edge of the sheet S, image formation on the sheet S begins. Image data to be printed is received along with a print instruction from an external device, such as a PC, via the communication I / F 130. The surface of the photosensitive drum 51 is exposed to light by the laser unit 7, thereby forming an electrostatic latent image based on the image data. The developing roller 55 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 51, thereby forming a toner image on the surface of the photosensitive drum 51. The transfer roller 53 then transports the sheet S between itself and the photosensitive drum 51, thereby transferring the toner image formed on the surface of the photosensitive drum 51 to the sheet S passing through the transfer nip TN. In this way, image formation on the first side of the sheet S is first performed. Then, the developer image formed on the sheet S by the process unit 4 is fixed to the sheet S using the fixing unit 6. Then, when the discharge sensor SE3 detects the leading edge of the sheet S that has passed between the heating roller 61 and the pressure roller 62 of the fixing unit 6, the discharge motor 109 is driven to rotate forward, and the sheet S on the first discharge path 201A is conveyed in the conveying direction. Then, when it is determined that the discharge sensor SE3 has switched off, the image forming process for the first side is completed.

[0118] As described above, immediately after powering on the MFP 1 and before the start of the printing process, the flapper 88 is in the first position 88A as its initial position. Therefore, when the image forming process is performed on the first side of the sheet S, the flapper 88 guides the sheet S conveyed by the conveying roller 36 to the first discharge path 201A where the cutter 10 is not provided.

[0119] Then, after the image formation process for the first side is performed in S43, the ASIC 105 executes the sheet reversing process in S44. In the sheet reversing process, when the trailing edge of the sheet S in the conveying direction reaches the reversing position, the ASIC 105 drives the discharge motor 109 to rotate in the reverse direction. As the discharge motor 109 is driven in the reverse direction, the first discharge rollers 87 rotate in the opposite direction to the rotation that conveys the sheet S in the conveying direction, and the sheet S is conveyed toward the re-conveyance path 202. The sheet S conveyed to the re-conveyance path 202 is conveyed toward the process unit 4 by the re-conveyance rollers 38 and 39. Thereafter, when the post-registration sensor SE2 detects the leading edge of the sheet S, the sheet reversing process ends.

[0120] Thereafter, in S45, the ASIC 105 performs the above-described flapper switching process (FIG. 12). In the flapper switching process of S45, as described above, the flapper 88 is switched from the first position 88A to the second position 88B. Thereafter, the flapper 88 guides the sheet S conveyed by the conveying roller 36 to the second discharge path 201B on which the cutter 10 is provided.

[0121] Next, in S46, the ASIC 105 executes image formation processing on the second side of the sheet S. This is basically the same as the image formation processing in S43, but differs in that the sheet S to be printed is a sheet S that has been printed on its first side via the re-conveyance path 202, and there is no need to pick up a new sheet S from the supply tray 31.

[0122] Thereafter, in S47, the ASIC 105 executes sheet cutting processing for the sheet S having images formed on both the first and second sides. This is basically the same as S5, so details are omitted.

[0123] Next, in S48, the ASIC 105 performs the flapper switching process (FIG. 13) described above. In the flapper switching process in S48, as described above, the flapper 88 is switched from the second position 88B to the first position 88A. Thereby, the flapper 88 thereafter guides the sheet S conveyed by the conveying roller 36 to the first discharge path 201A where the cutter 10 is not provided.

[0124] Thereafter, in S49, the ASIC 105 determines whether the job being executed has a next sheet to be printed. If the determination is that a next sheet has to be printed (S49: YES), the process returns to S43 and the processes from S43 onward are executed again.

[0125] On the other hand, if there is no next sheet to be printed (S49: NO), the process proceeds to S50.

[0126] In S50, the ASIC 105 drives the cutter motor 106 in the reverse direction to move the slide holder 16 from the completion position KP toward the initial position FP. Then, the ASIC 105 waits until the slide holder 16 reaches the initial position FP, and stops the cutter motor 106 when the slide holder 16 reaches the initial position FP (S51).

[0127] Subsequently, in S52, the ASIC 105 turns off the heater 63 and stops the main motor 108 (S53), and then ends the sheet single-sided printing and cutting process.

[0128] The order of the processes of S50 to S53 may be reversed. Also, when printing of the final sheet has been completed and an instruction for the next job has been entered, the heater 63 may not be turned off in S52, and the next job may be executed while the main motor 108 continues to rotate forward.

[0129] As described in detail above, the MFP1 according to the first embodiment includes a cutter 10 that is arranged at a cutter position downstream of the fixation unit 6 in the sheet transport direction on the transport path along which the sheet S is transported after passing through the image forming unit and the fixation unit 6, and that cuts the sheet S on which an image has been fixed, a cutter motor 106 that drives the cutter 10, a DC motor driver 118 that controls the drive of the cutter motor 106, a first discharge path 201A for discharging the sheet S outside the main body 20 without passing through the cutter position, a second discharge path 201B for discharging the sheet S outside the main body 20 via the cutter position, a flapper 88 that guides the sheet S to either the first discharge path 201A or the second discharge path 201B, and a flapper switching circuit 119 that can switch the direction and current state of the current flowing between one end and the other end of the coil 90. On the other hand, a flapper solenoid 89 that switches the flapper 88 between a first state in which the sheet S is guided to the first discharge path 201A and a second state in which the sheet S is guided to the second discharge path 201B is a self-holding solenoid, and the flapper switching circuit has a first input terminal IN1, a second input terminal IN2, a first output terminal OUT1, and a second output terminal OUT2, and the first output terminal OUT1 is connected to one end of a coil 90, and the second output terminal OUT2 is connected to the other end of the coil 90, The first input terminal IN1 and the second input terminal IN2 are each connected to ASIC 105, and the direction and current flowing through one end and the other end of coil 90 can be switched by control signals input from ASIC 105 to the first input terminal IN1 and the second input terminal IN2.Thus, while four terminals are normally required to switch flapper 88, switching can be performed using the first input terminal IN1 and the second input terminal IN2, thereby reducing the number of terminals on ASIC 105. Furthermore, when current flows from one end T1 to the other end T2 of the coil 90, the flapper solenoid 89 switches the flapper 88 from the first state to the second state by the plunger 150, and when the current to the coil 90 is turned off in that state, the flapper 88 is maintained in the second state by the permanent magnet 151 and the plunger 150, so that it is possible to switch and maintain the discharge path to be discharged in only a very short current-carrying time. As a result, it is possible to achieve power savings compared to conventional methods and also to suppress heat generation. Furthermore, in flapper solenoid 89, the direction of the magnetic field generated by coil 90 and the direction of the magnetic field generated by permanent magnet 151 are opposite to each other due to current flowing from the other end T2 to one end T1 of coil 90, and this switches flapper 88 from the first state to the second state, and when current to coil 90 is turned off in this state, flapper 88 is maintained in the first state, so that it is possible to switch and maintain the discharge path to be discharged in only a very short current-carrying time. As a result, it is possible to achieve power savings compared to conventional methods and also to suppress heat generation. It also has an ASIC 105 that controls the image forming unit and the cutter 10, and the flapper switching circuit 119 has a first input terminal IN1, a second input terminal IN2, a first output terminal OUT1, and a second output terminal OUT2, and the first output terminal OUT1 is connected to one end T1 of the coil 90, and the second output terminal is connected to the other end T2 of the coil 90, and the first input terminal IN1 and the second input terminal IN2 are each connected to the ASIC 105, and the direction and current flowing through one end T1 and the other end T2 of the coil 90 can be switched by control signals input from the ASIC 105 to the first input terminal IN1 and the second input terminal IN2. The flapper switching circuit 119 has a first NPN transistor Q1, a second NPN transistor Q3, a third NPN transistor Q4, a fourth NPN transistor Q6, a first PNP transistor Q2, a second PNP transistor Q5, a first resistor R11, a second resistor R12, a third resistor R21, and a fourth resistor R22. The first NPN transistor Q1 has a base connected to the first input terminal IN1 via the first resistor R11, an emitter connected to the reference potential section, and a collector connected to the base of the first PNP transistor Q2. The first PNP transistor Q2 has a collector connected to the first output terminal OUT1 and an emitter connected to the power supply. The second NPN transistor Q3 has a base connected to the first input terminal IN1 via the second resistor R12, an emitter connected to the reference potential section, and a collector connected to the base of the first PNP transistor Q2. The third NPN transistor Q4 has its base connected to the second input terminal IN2 via a third resistor R21, its emitter connected to the reference potential, and its collector connected to the junction between the second PNP transistor Q5 and the second output terminal OUT2. The third NPN transistor Q4 has its base connected to the second input terminal IN2 via a third resistor R21, its emitter connected to the reference potential, and its collector connected to the base of the second PNP transistor Q5. The second PNP transistor Q5 has its collector connected to the second output terminal OUT2 and its emitter connected to the power supply. The fourth NPN transistor Q6 has its base connected to the second input terminal IN2 via a fourth resistor R22, its emitter connected to the reference potential, and its collector connected to the junction between the first PNP transistor Q2 and the first output terminal OUT1. Therefore, the control signals input from ASIC 105 to the first input terminal IN1 and the second input terminal IN2 control the on or off of each transistor, making it possible to switch the direction and current flowing through one end T1 and the other end T2 of coil 90. Furthermore, when the flapper 88 is in the first state, the flapper switching circuit 119 starts energizing the coil 90 from one end T1 to the other end T2 (S21) and then turns off the energization to the coil 90 after a predetermined time has elapsed (S23), thereby switching the flapper 88 from the first state to the second state and maintaining it in the second state, so that it is possible to transition the flapper 88 from the first state to the second state and maintain it in the second state in only a very short energization time. Furthermore, when the flapper 88 is in the second state, the flapper switching circuit 119 starts energizing the coil 90 from the other end T2 to one end T1 (S31) and then turns off the energization to the coil 90 after a predetermined time has elapsed (S33), thereby switching the flapper 88 from the second state to the first state and maintaining it in the first state, so that it is possible to transition the flapper 88 from the second state to the first state and maintain it in the first state in only a very short energization time.

[0130] Second Embodiment Next, an MFP according to a second embodiment will be described with reference to Fig. 15. In the following description, the same reference numerals as those in the configuration of the MFP1 according to the first embodiment shown in Figs. 1 to 14 indicate the same or corresponding parts as those in the configuration of the MFP1 according to the first embodiment.

[0131] The schematic configuration of the MFP according to the second embodiment is almost the same as that of the MFP 1 according to the first embodiment. In addition, the various control processes are also almost the same as those of the MFP 1 according to the first embodiment. However, the electrical configuration of the MFP 1 according to the first embodiment is different, particularly with respect to the flapper switching circuit 119 shown in FIG.

[0132] The electrical configuration of the flapper switching circuit 119 according to the second embodiment will be described below with reference to Fig. 15. Fig. 15 particularly illustrates only the flapper switching circuit 119 provided on the main board 100 and the electrical configuration of the MFP 1 related thereto.

[0133] 15 , the flapper switching circuit 119 according to the second embodiment includes a first NPN transistor Q1, a second NPN transistor Q2, a third NPN transistor Q3, a fourth NPN transistor Q4, a fifth NPN transistor Q5, a sixth NPN transistor Q6, a first resistor R11, a second resistor R12, a third resistor R21, a fourth resistor R22, a fifth resistor R13, and a sixth resistor R23. On the other hand, as input / output terminals, the flapper switching circuit 119 includes a first input terminal IN1 for receiving a control signal output from an output port P1 of the ASIC 105, a second input terminal IN2 for receiving a control signal output from an output port P2 of the ASIC 105, a first output terminal OUT1 connected to one end T1 of a coil 90 included in the flapper solenoid 89, and a second output terminal OUT2 connected to the other end T2 of the coil 90 included in the flapper solenoid 89. The flapper switching circuit 119 is also provided with DC 24V generated in the low voltage power supply board 110 as a power source.

[0134] In addition, the first NPN transistor Q1 corresponds to the "first semiconductor transistor," the second NPN transistor Q2 corresponds to the "second semiconductor transistor," the third NPN transistor Q3 corresponds to the "third semiconductor transistor," the fourth NPN transistor Q4 corresponds to the "fourth semiconductor transistor," the fifth NPN transistor Q5 corresponds to the "fifth semiconductor transistor," and the sixth NPN transistor Q6 corresponds to the "sixth semiconductor transistor."

[0135] Among the semiconductor transistors included in the flapper switching circuit 119, the first NPN transistor Q1 has a base connected to the first input terminal IN1 via a first resistor R11, an emitter connected to ground GND, and a collector connected to the base of the second NPN transistor Q2. The second NPN transistor Q2 has an emitter connected to the first output terminal OUT1, a collector connected to a 24V DC power supply, and a base connected to a fifth resistor R13. The third NPN transistor Q3 has a base connected to the first input terminal IN1 via a second resistor R12, an emitter connected to ground GND, and a collector connected to a connection point CP2 between the fifth NPN transistor Q5 and the second output terminal OUT2. The fourth NPN transistor Q4 has a base connected to the second input terminal IN2 via a third resistor R21, an emitter connected to ground GND, and a collector connected to the base of the fifth NPN transistor Q5. The fifth NPN transistor Q5 has its emitter connected to the second output terminal OUT2, its collector connected to a 24 V DC power supply, and its base connected via a sixth resistor R23. The sixth NPN transistor Q6 has its base connected to the second input terminal IN2 via a fourth resistor R22, its emitter connected to ground GND, and its collector connected to a connection point CP1 between the first NPN transistor Q1 and the first output terminal OUT1.

[0136] Here, the flapper switching circuit 119 of the second embodiment has basically the same configuration as the flapper switching circuit 119 of the first embodiment, but a second NPN transistor Q2 and a fifth resistor R13 are arranged in place of the first PNP transistor Q2 in the first embodiment. Similarly, a fifth NPN transistor Q5 and a sixth resistor R23 are arranged in place of the second PNP transistor Q5 in the first embodiment.

[0137] Also in the flapper switching circuit 119 of the second embodiment, either an on (=H) or off (=L) control signal is input to the flapper switching circuit 119 from the output port P1 and the output port P2 of the ASIC 105. The input control signals are the same as those in the first embodiment, and specifically, the combinations of the control signals input from each output port are the three patterns shown in FIG.

[0138] The details of each pattern are the same as those of the first embodiment, so a detailed description will be omitted. The presence or absence and direction of current flowing through the coil 90 of the flapper solenoid 89 are also the same in each pattern (FIGS. 6 and 9). In the second embodiment, an NPN transistor is used instead of the PNP transistor of the first embodiment. However, the 24V DC power supply is also connected to the base of the second NPN transistor Q2 via the fifth resistor R13. Therefore, when the first NPN transistor Q1 is turned on, current flows from the 24V DC power supply connected to the collector side of the second NPN transistor Q2 to the ground GND on the emitter side of the first NPN transistor Q1 via the fifth resistor R13, and current also flows from the base to the emitter of the second NPN transistor Q2. In other words, when the first NPN transistor Q1 is turned on, the second NPN transistor Q2 is also turned on. Similarly, the 24V DC power supply is also connected to the base of the fifth NPN transistor Q5 via the sixth resistor R23, so when the fourth NPN transistor Q4 is turned on, current flows from the 24V DC power supply connected to the collector side of the fifth NPN transistor Q5 through the sixth resistor R23 to the ground GND on the emitter side of the fourth NPN transistor Q4, and current also flows from the base to the emitter of the fifth NPN transistor Q5. In other words, when the fourth NPN transistor Q4 is turned on, the fifth NPN transistor Q5 is also turned on.

[0139] In the flapper switching circuit 119 of the second embodiment, it is also possible to switch the direction of current flowing through the flapper solenoid 89 and whether or not current is being applied by combining control signals sent from the ASIC 105, thereby switching the position of the flapper 88 between a first position 88A and a second position 88B. Note that, since the flapper solenoid 89 is a self-holding solenoid in the second embodiment as well, it is not necessary to continue to pass current in order to maintain the plunger 150 in the initial position and the attracted position, and this makes it possible to suppress heat generation in the coil and reduce power consumption.

[0140] As described above in detail, in the MFP1 according to the second embodiment, the flapper switching circuit 119 includes a first NPN transistor Q1, a second NPN transistor Q2, a third NPN transistor Q3, a fourth NPN transistor Q4, a fifth NPN transistor Q5, a sixth NPN transistor Q6, a first resistor R11, a second resistor R12, a third resistor R21, a fourth resistor R22, a fifth resistor R13, and a sixth resistor R23. The first NPN transistor Q1 has a base connected to the first input terminal IN1 via the first resistor R11, an emitter connected to ground GND, and a collector connected to the base of the second NPN transistor Q2. The second NPN transistor Q2 has an emitter connected to the first output terminal OUT1, and a collector connected to a 24V DC power supply and also connected to the base via the fifth resistor R13. The third NPN transistor Q3 has its base connected to the first input terminal IN1 via a second resistor R12, its emitter connected to ground GND, and its collector connected to a junction point CP2 between the fifth NPN transistor Q5 and the second output terminal OUT2. The fourth NPN transistor Q4 has its base connected to the second input terminal IN2 via a third resistor R21, its emitter connected to ground GND, and its collector connected to the base of the fifth NPN transistor Q5. The fifth NPN transistor Q5 has its emitter connected to the second output terminal OUT2, its collector connected to a 24V DC power supply, and its base connected to a sixth resistor R23. The sixth NPN transistor Q6 has its base connected to the second input terminal IN2 via a fourth resistor R22, its emitter connected to ground GND, and its collector connected to a junction point CP1 between the first NPN transistor Q1 and the first output terminal OUT1. Therefore, the control signals input from ASIC 105 to the first input terminal IN1 and the second input terminal IN2 control the on or off of each transistor, making it possible to switch the direction and current flowing through one end T1 and the other end T2 of coil 90.

[0141] The present invention is not limited to the above-described embodiment, and it goes without saying that various improvements and modifications are possible within the scope of the present invention. For example, in the above embodiment, bipolar transistors or field effect transistors are used as the semiconductor transistors of the flapper switching circuit 119, but any other semiconductor transistors may be used.

[0142] In addition, in the above embodiment, the image forming apparatus is described as an example of a multifunction device that has a printer function as well as a fax function, a copy function, and a scanner function, but it may also be, for example, a printer that has only a printer function. [Explanation of symbols]

[0143] 1...MFP (image forming apparatus), 2...image forming main body (apparatus main body), 6...fuser (fuser section), 10...cutter, 88...flapper, 89...flapper solenoid, 90...coil, 105...ASIC, 119...flapper switching circuit, 150...plunger, 151...permanent magnet, 201A...first discharge path, 201B...second discharge path, S...sheet, Q1...first semiconductor transistor (first NPN transistor, first P-channel field effect transistor), Q2...second semiconductor transistor (first PN Q1...first N-channel field effect transistor), Q2...third semiconductor transistor (second NPN transistor, second P-channel field effect transistor), Q3...third semiconductor transistor (second NPN transistor, second P-channel field effect transistor), Q4...fourth semiconductor transistor (third NPN transistor, third P-channel field effect transistor), Q5...fifth semiconductor transistor (second PNP transistor, second N-channel field effect transistor), Q6...sixth semiconductor transistor (fourth NPN transistor, fourth P-channel field effect transistor)

Claims

1. an image forming unit that forms a developer image on a sheet; a fixing section including a heating rotor that heats the sheet and a pressure rotor that nips the sheet between the heating rotor and the sheet, and that fixes the developer image formed on the sheet; a cutter disposed at a cutter position downstream of the fixing unit in a sheet conveyance direction in a conveyance path along which the sheet is conveyed after passing through the image forming unit and the fixing unit, the cutter cutting the sheet on which the developer image has been fixed; a cutter motor that drives the cutter; a motor driver for controlling the drive of the cutter motor; an apparatus main body having the transport path, the apparatus main body having a first discharge path as part of the transport path for discharging the sheet to the outside of the apparatus main body without passing through the cutter position, and a second discharge path for discharging the sheet to the outside of the apparatus main body via the cutter position; a flapper that guides the sheet to one of the first discharge path and the second discharge path; a self-holding solenoid having a coil, the solenoid switching the flapper between a first state in which the sheet is guided to the first discharge path and a second state in which the sheet is guided to the second discharge path depending on the direction of current flowing between one end and the other end of the coil; a flapper switching circuit capable of switching the direction and energization state of a current flowing between one end and the other end of the coil; a control unit electrically connected to the image forming unit, the fixing unit, the motor driver, and the flapper switching circuit, The flapper switching circuit an image forming apparatus having a first input terminal, a second input terminal, a first output terminal, and a second output terminal, the first output terminal being connected to one end of the coil, the second output terminal being connected to the other end of the coil, the first input terminal and the second input terminal being connected to the control unit, and the direction and current flowing through one end and the other end of the coil can be switched by a control signal input from the control unit to the first input terminal and the second input terminal.

2. The flapper switching circuit further a first semiconductor transistor, a second semiconductor transistor, a third semiconductor transistor, a fourth semiconductor transistor, a fifth semiconductor transistor, and a sixth semiconductor transistor; the first semiconductor transistor has a control terminal connected to the first input terminal, an output terminal connected to a reference potential portion, and an input terminal connected to the control terminal of the second semiconductor transistor; the second semiconductor transistor has an output terminal connected to the first output terminal and an input terminal connected to a power supply; the third semiconductor transistor has a control terminal connected to the first input terminal, an output terminal connected to a reference potential portion, and an input terminal connected to a connection point between the fifth semiconductor transistor and the second output terminal; the fourth semiconductor transistor has a control terminal connected to the second input terminal, an output terminal connected to a reference potential portion, and an input terminal connected to the control terminal of the fifth semiconductor transistor; the fifth semiconductor transistor has an output terminal connected to the second output terminal and an input terminal connected to a power supply; 2. The image forming apparatus according to claim 1, wherein the sixth semiconductor transistor has a control terminal connected to the second input terminal, an output terminal connected to a reference potential portion, and an input terminal connected to a connection point between the first semiconductor transistor and the first output terminal.

3. The flapper switching circuit further a first NPN transistor, a second NPN transistor, a third NPN transistor, a fourth NPN transistor, a first PNP transistor, a second PNP transistor, a first resistor, a second resistor, a third resistor, and a fourth resistor; the first NPN transistor has a base connected to the first input terminal via the first resistor, an emitter connected to a reference potential portion, and a collector connected to the base of the first PNP transistor; the first PNP transistor has a collector connected to the first output terminal and an emitter connected to a power supply; the second NPN transistor has a base connected to the first input terminal via the second resistor, an emitter connected to a reference potential portion, and a collector connected to a connection point between the second PNP transistor and the second output terminal; the third NPN transistor has a base connected to the second input terminal via the third resistor, an emitter connected to a reference potential portion, and a collector connected to the base of the second PNP transistor; the second PNP transistor has a collector connected to the second output terminal and an emitter connected to a power supply; 2. The image forming apparatus according to claim 1, wherein the fourth NPN transistor has a base connected to the second input terminal via the fourth resistor, an emitter connected to a reference potential portion, and a collector connected to a connection point between the first PNP transistor and the first output terminal.

4. The flapper switching circuit further a first NPN transistor, a second NPN transistor, a third NPN transistor, a fourth NPN transistor, a fifth NPN transistor, a sixth NPN transistor, a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor; the first NPN transistor has a base connected to the first input terminal via the first resistor, an emitter connected to a reference potential portion, and a collector connected to the base of the second NPN transistor; the second NPN transistor has an emitter connected to the first output terminal, a collector connected to a power supply, and a base connected via the fifth resistor; the third NPN transistor has a base connected to the first input terminal via the second resistor, an emitter connected to a reference potential portion, and a collector connected to a connection point between the fifth NPN transistor and the second output terminal; the fourth NPN transistor has a base connected to the second input terminal via a third resistor, an emitter connected to a reference potential portion, and a collector connected to the base of the fifth NPN transistor; the fifth NPN transistor has an emitter connected to the second output terminal, a collector connected to a power supply, and a base connected via the sixth resistor; 2. The image forming apparatus according to claim 1, wherein the sixth NPN transistor has a base connected to the second input terminal via a fourth resistor, an emitter connected to a reference potential portion, and a collector connected to a connection point between the first NPN transistor and the first output terminal.

5. The flapper switching circuit 2. The image forming apparatus according to claim 1, wherein when the flapper is in a first state, the flapper is switched from the first state to the second state and maintained in the second state by turning off the power to the coil after a predetermined time has elapsed since the power started to be supplied from one end of the coil to the other end.

6. The self-holding solenoid is The image forming apparatus of claim 1 further comprises a plunger and a permanent magnet, and when current flows from one end of the coil to the other, the plunger switches the flapper from the first state to the second state, and when current to the coil is turned off in that state, the permanent magnet and the plunger maintain the flapper in the second state.

7. The self-holding solenoid is The image forming apparatus of claim 6, wherein the flapper switches from the first state to the second state when the direction of the magnetic field generated by the coil and the direction of the magnetic field generated by the permanent magnet become opposite due to current flowing from the other end of the coil to one end, and when power to the coil is turned off in that state, the flapper is maintained in the first state.

8. The flapper switching circuit 8. An image forming apparatus as described in claim 7, wherein when the flapper is in the second state, the flapper is switched from the second state to the first state and maintained in the first state by turning off the power to the coil after a predetermined time has elapsed since the power started to be supplied from the other end of the coil to the one end.

Images