Image forming apparatus

Abstract

To provide a technique that can accurately detect a sheet around a cutter.SOLUTION: A printer 1 comprises: an apparatus body 2 that has a conveyance path 201 of a sheet S; a fuser 6 that has a heating roller 61, and fixes an image formed on the sheet S to the sheet S; a first ejection roller 85 that is located on the downstream side of the fuser 6 and conveys the sheet S; a second ejection roller 86 that is located on the downstream side in the conveyance direction of the first ejection roller 85 and ejects the sheet S conveyed by the first ejection roller 85 to the outside of the apparatus body 2; a cutter 10 that is located at a cutter position B being a position between the first ejection roller 85 and the second ejection roller 86 in the conveyance direction, and can cut the sheet S in a cut direction intersecting the conveyance direction; and a sheet detection sensor SE4 that detects whether the sheet S is present at a first detection position between the first ejection roller 85 and the second ejection roller 86 in the conveyance direction.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This application relates to an image forming apparatus that cuts a sheet on which an image is formed with a cutter.

Background Art

[0002] Patent Document 1 describes an image forming apparatus that conveys a sheet sent out from an image forming unit to the position of a cutter and cuts the sheet in a direction orthogonal to the conveyance direction at the central portion in the conveyance direction of the sheet. This image forming apparatus includes a sheet detection unit, and controls a branch guide in response to the sheet detection unit detecting a sheet, and discharges the cut sheet separately to a first discharge tray and a second discharge tray.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the image forming apparatus described in Patent Document 1, accurately detecting a sheet around the cutter is not considered.

[0005] An object of this application is to provide a technology that enables accurate detection of a sheet around a cutter.

Means for Solving the Problems

[0006] To achieve the above objective, the present invention provides an image forming apparatus comprising: an apparatus body having a sheet transport path; a heating rotating body; a pressurizing rotating body that forms a nip between itself and the heating rotating body; a fixer for fixing an image formed on a sheet to the sheet; a first discharge roller located downstream of the fixer in the sheet transport direction along the transport path and transporting the sheet; a second discharge roller located downstream of the first discharge roller in the transport direction and discharging the sheet transported by the first discharge roller to the outside of the apparatus body; a cutter located at a cutter position between the first and second discharge rollers in the transport direction and capable of cutting the sheet in a cutting direction intersecting the transport direction; and a first sensor for detecting whether or not a sheet is present at a first detection position between the first and second discharge rollers in the transport direction.

[0007] According to the image forming apparatus of the present invention, a cutter is placed between a first discharge roller and a second discharge roller in the transport direction, and a detection mechanism is used to detect whether or not a sheet is present at a detection position between the first discharge roller and the second discharge roller in the same manner, thereby enabling accurate detection of the sheet around the cutter.

[0008] The device further comprises a control unit, which, based on the output of the first sensor, drives the first discharge roller and the second discharge roller with a drive amount required to transport the sheet from when the front end of the sheet reaches the first detection position until the cutting position of the sheet reaches the cutter position, and then performs a transport process to stop the transport of the sheet, and after the transport process, performs a cutting process to cut the sheet in the cutting direction using a cutter.

[0009] In this way, the sheet is cut based on the output of the first sensor located near the cutter position. The sheet is transported until it reaches the cutter position, and then cut at that position, making it possible to cut the sheet precisely at the cutting point.

[0010] Furthermore, the control unit receives print data including the sheet size of the sheet, and performs a drive amount acquisition process to acquire a drive amount based on the sheet size included in the received print data. In the transport process, the first discharge roller and the second discharge roller are driven with the drive amount acquired by the drive amount acquisition process, and then the transport of the sheet is stopped.

[0011] This allows the drive amount to be obtained based on the sheet size, which is simple information contained in the received print data, thus simplifying the process of obtaining the drive amount.

[0012] Furthermore, the system includes a second sensor that detects whether or not a sheet is present at a second detection position, which is upstream of the first sensor in the transport direction. The control unit detects, based on the output of the second sensor, when the front end of the sheet has reached the second detection position and when the rear end of the sheet has reached the second detection position. Based on the detected front and rear ends of the sheet, the control unit performs a sheet length acquisition process to obtain the sheet length in the transport direction, and a drive amount acquisition process to obtain a drive amount based on the sheet length obtained by the sheet length acquisition process. In the transport process, the first discharge roller and the second discharge roller are driven by the drive amount obtained by the drive amount acquisition process, and then the transport of the sheet is stopped.

[0013] This allows the drive amount to be obtained based on the measured sheet length, making it possible to accurately cut the sheet at the intended cutting position even if the sheet shrinks and its length becomes shorter than the original length.

[0014] Furthermore, the control unit is characterized in that, in the sheet length acquisition process, it acquires the sheet length in the sheet transport direction based on the amount of sheet transported from the detection of the front end of the sheet to the detection of the rear end of the sheet, based on the output of the second sensor.

[0015] This allows the sheet length to be obtained based on the output of a second sensor already installed in the image forming apparatus, thereby reducing the overall manufacturing cost of the image forming apparatus.

[0016] Furthermore, the system includes a discharge motor for driving the first discharge roller and the second discharge roller, and the control unit is characterized in that, during the transport process, if the first sensor does not detect a sheet even after a predetermined time has elapsed since the discharge motor was started, the control unit stops the discharge motor.

[0017] This makes it possible to accurately detect jams in the sheets during transport and to perform appropriate error handling in response to the jams.

[0018] Furthermore, the system includes a main motor that rotates either the heating rotating body or the pressurizing rotating body, and the control unit is characterized in that, during the transport process, if the first sensor does not detect a sheet even after a predetermined time has elapsed since the discharge motor was started, the main motor is also stopped.

[0019] This makes it possible to perform error handling more accurately in response to jams.

[0020] Furthermore, the device body further includes a display panel, and the control unit is characterized in that, if the first sensor does not detect a sheet even after a predetermined time has elapsed since the discharge motor was started during the transport process, it displays a notification screen on the display panel indicating that a jam has occurred.

[0021] This makes it possible to accurately notify the user of any jams that occur in the sheets during the transport process.

[0022] The device further includes a discharge motor for driving a first discharge roller and a second discharge roller. The control unit, after the cutting process, drives the first discharge roller and the second discharge roller to perform a discharge process in which the cut sheet is discharged to the outside of the device body. During the discharge process, if the first sensor detects a sheet even after a predetermined time has elapsed since the discharge motor was started, the control unit stops the discharge motor.

[0023] This makes it possible to accurately determine the occurrence of sheet jams during the discharge process after cutting and to accurately perform error processing according to the occurrence of jams.

[0024] The apparatus main body further has a display panel, and when the control unit does not detect the sheet with the first sensor even after a predetermined time has elapsed since starting the drive of the discharge motor during the discharge process, the control unit causes the display panel to display a notification screen notifying that a jam has occurred.

[0025] This makes it possible to accurately notify the user of the occurrence of sheet jams during the discharge process after cutting.

[0026] The cutter has a blade for cutting the sheet and a cutting motor for moving the blade in the cutting direction. When the first sensor changes from a state of detecting the sheet to a state of not detecting the sheet while the cutting motor is driving and the discharge motor is not driving during the cutting process, the control unit stops the drive of the cutting motor.

[0027] This makes it possible to accurately determine that the sheet has been pulled out during the cutting process and to accurately perform error processing accordingly.

[0028] The first sensor detects whether a sheet exists at a detection position between the cutter and the second discharge roller.

[0029] This makes it possible to accurately detect the sheet around the cutter.

[0030] The device further includes a cover that can be opened and closed to cover the transport path between the first discharge roller and the second discharge roller, and the first sensor outputs a first signal when the cover is open and when the cover is closed and a sheet is detected, and outputs a second signal when the cover is closed and a sheet is not detected, and the control unit determines that the cover is open when the first signal is output from the first sensor when the sheet is not being transported by the first and second discharge rollers.

[0031] This allows a single first sensor to handle both sheet detection and cover open / closed state detection, thereby reducing the overall manufacturing cost of the image forming apparatus.

[0032] The device further includes a third discharge roller located in a discharge path branched from the transport path between the fuser and the first discharge roller, which is located at a position shorter than the length of the transport path from the fuser to the second discharge roller, and which discharges the sheet to the outside of the device body. The control unit receives print data including information indicating whether or not to cut the sheet, and if the information included in the received print data indicates that the sheet should not be cut, the control unit transports the sheet using the third discharge roller and discharges the sheet to the outside of the device body without cutting it.

[0033] As a result, when a sheet is not cut, it is discharged to the outside of the device via a shorter transport path, making it possible to quickly discharge uncut sheets to the outside of the device.

[0034] The system further includes a flapper that can be switched between a first position for guiding the sheet toward a first discharge roller and a second position for guiding the sheet toward a third discharge roller. The control unit is characterized in that, when the cutting status information indicates that cutting should be performed, the flapper is switched to the first position after the front end of the sheet has left the fuser but before it reaches the flapper, and when the cutting status information indicates that cutting should not be performed, the flapper is switched to the second position after the front end of the sheet has left the fuser but before it reaches the flapper.

[0035] This is convenient because, based on the cutting information included in the print data, the sheet is automatically guided towards either the first or third discharge roller.

[0036] Furthermore, the length of the transport path from the fuser to the cutter is longer than half the length of the sheet in the transport direction of the sheet that can be cut.

[0037] This eliminates the issue of the sheet being pinched by the fuser's nip when the sheet is cut at the cutter position, thus preventing heat from being applied to the sheet from the heating rotating body when the rotation of the pressurizing rotating body has stopped.

[0038] Furthermore, the system further comprises a discharge motor for driving a first discharge roller, a roller located between the first discharge roller and the fuser, and a main motor for driving the roller and the fuser. The length of the transport path from the roller to the cutter is longer than half the length of the sheet in the transport direction of the sheet to be cut, and the control unit keeps the main motor running during the cutting process.

[0039] This allows the sheet to be held in place at the cutter position by stopping only the discharge motor, without stopping the main motor's drive of the rollers or fuser when cutting the sheet.

[0040] Furthermore, the image forming unit, located upstream of the fuser in the transport direction, and forming an image on a sheet, is characterized by further comprising: a photoreceptor drum; a developing roller that supplies toner to the photoreceptor drum; and a transfer roller that transfers the toner image formed on the photoreceptor drum to the sheet.

[0041] This makes it possible to accurately detect the sheet around the cutter even in electrophotographic image forming apparatuses. [Brief explanation of the drawing]

[0042] [Figure 1] This is a cross-sectional view showing the schematic configuration of a monochrome laser printer according to the first embodiment of the present application. [Figure 2] Figure 1 is a perspective view showing the schematic configuration of the cutter included in the monochrome laser printer. [Figure 3] Figure 1 is a block diagram showing the control configuration of a monochrome laser printer. [Figure 4] This diagram shows the cutting position of the sheet ((a)) and the sheet cut at that cutting position. [Figure 5] This diagram shows the operation of the sheet detection sensor in the following states: (a) with the cover open, (b) with the cover closed and no sheet detected, and (c) with the cover closed and sheet detected. [Figure 6] Figure 1 is a flowchart showing the printing process in a monochrome laser printer. [Figure 7] Figure 6 is a flowchart detailing the sheet printing and cutting process included in the printing process. [Figure 8] Figure 7 is a flowchart showing the detailed procedure for determining the number of sheet transport steps based on the set sheet length, which is included in the sheet printing and cutting process. [Figure 9] Figure 7 is a flowchart detailing the sheet transport process to the cutter position, which is included in the sheet printing and cutting process. [Figure 10] Figure 7 is a flowchart showing the detailed steps of the sheet cutting process included in the sheet printing and cutting process. [Figure 11] Figure 10 is a flowchart showing the detailed procedure for error stopping processing due to sheet pull-out detection, which is included in the sheet cutting process. [Figure 12] Figure 7 is a flowchart detailing the error termination procedure caused by JAM (Jam Error) included in the sheet printing and cutting process. [Figure 13] Figure 1 is a flowchart showing the procedure for determining the cover state in a monochrome laser printer. [Figure 14]This flowchart shows a detailed procedure for the sheet printing and cutting process in a monochrome laser printer according to a second embodiment of the present application. [Figure 15] Figure 14 is a flowchart detailing the steps involved in determining the number of sheet transport steps based on the measured sheet length, which is included in the sheet printing and cutting process. [Figure 16] This figure illustrates the process for determining the number of sheet transport steps based on the measured sheet length in Figure 15. [Modes for carrying out the invention]

[0043] The embodiments of this application will be described in detail below with reference to the drawings.

[0044] (First Embodiment) Figure 1 is a cross-sectional view showing the schematic configuration of a monochrome laser printer 1 according to the first embodiment of the present application. The monochrome laser printer 1 is an example of an image forming apparatus. Hereinafter, the monochrome laser printer 1 will be abbreviated as printer 1. Printer 1 comprises a main body 2, a transport unit 3, an image forming unit 4, a fuser 6, a cutter 10, and an operation panel PA. Hereinafter, for the sake of convenience of explanation, the vertical and horizontal directions of printer 1 will be defined as shown by the arrows in Figure 1. The side of the paper facing you will be defined as left, and the side facing you will be defined as right.

[0045] The device body 2 includes a front cover 21, a supply tray 31, an output tray 22, a transport path 201, and a re-transport path 202. The front cover 21 is attached to the front of the device body 2 in a manner that allows it to be opened and closed. The supply tray 31 is attached to the bottom of the device body 2 in a manner that allows it to be attached and detached. A sheet S is placed on the supply tray 31. The sheet S is a standard-sized sheet, such as A4 size. The sheet S is a paper medium such as plain paper or cardboard, but is not limited to this, and may also be OHP film. The output tray 22 is provided on the top of the device body 2, and the sheet S on which the image is formed is placed on the output tray 22.

[0046] The transport path 201 is a path for transporting the sheet S placed on the supply tray 31 along the transport direction towards the discharge tray 22 via the image forming unit 4. The transport path 201 branches from the first branching position D1 into the first discharge path 201A and the second discharge path 201B. Therefore, the sheet S transported via the image forming unit 4 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.

[0047] The re-transport path 202 is a path for transporting the sheet S, on which an image has been formed on one side, inverted and again toward the image forming unit 4. The re-transport path 202 branches off from the transport path 201 at the second branching position D2 and rejoins the transport path 201 at the merging position J on the upstream side of the transport direction of the pre-register sensor SE1.

[0048] The transport unit 3 includes a pickup roller 33, a separation roller 34, a registration roller 35, a roller 36, a first discharge roller 85, a second discharge roller 86, a third discharge roller 87, a flapper 88, re-transport rollers 38, 39, a main motor 108 (see Figure 3), and a discharge motor 109 (see Figure 3).

[0049] The pickup roller 33 picks up the sheets S in the supply tray 31 that have been pushed upward by the sheet pressing plate 32 and transports them toward the transport path 201. The separation roller 34 separates the sheets S picked up by the pickup roller 33 one by one.

[0050] The registration roller 35 is positioned upstream of the image forming unit 4 in the transport path 201. After aligning the direction of the front end of the sheet S, the registration roller 35 transports the sheet S toward the image forming unit 4. The transport direction of the registration roller 35 is from front to back. The roller 36 transports the sheet S after it has passed through the fuser 6 toward the first discharge roller 85 or the third discharge roller 87. The transport direction of the fuser 6 and the roller 36 is from front to back and diagonally upward.

[0051] The first discharge roller 85 and the second discharge roller 86 are located in the first discharge path 201A. The first discharge roller 85 and the second discharge roller 86 are roller pairs consisting of a driven roller and a driven roller. The first discharge roller 85 is located upstream of the cutter position B where the cutter 10 is located, and the second discharge roller 86 is located downstream of the cutter position B.

[0052] The first discharge roller 85 and the second discharge roller 86 discharge the sheet S to the discharge tray 22 by rotating in the forward direction. Forward rotation is a rotation that transports the sheet S in the transport direction and corresponds to counterclockwise rotation with the left-right direction of the main body of the device 2 as the axis. The transport direction in which the first discharge roller 85 transports the sheet is from rear to front and upward. The direction in which the RA86 transports the seats is from rear to front.

[0053] Meanwhile, the third discharge roller 87 is located in the second discharge path 201B. The third discharge roller 87 is also a roller pair consisting of a drive roller and a driven roller. The third discharge roller 87 discharges the sheet S to the discharge tray 22 by rotating in the forward direction. The third discharge roller 87 also transports the sheet S to the re-transport path 202 by rotating in the reverse direction, which is the opposite direction to the forward rotation. Reverse rotation is a rotation that transports the sheet S in the opposite direction to the transport direction, and corresponds to a clockwise rotation with the left-right direction of the device body 2 as the axis. In other words, the transport direction in which the sheet is transported when the third discharge roller 87 rotates in the forward direction is from rear to front, and the transport direction in which the sheet is transported when the third discharge roller rotates in the reverse direction is from front to rear.

[0054] Retransport rollers 38 and 39 are arranged in the retransport path 202. The retransport rollers 38 and 39 transport the sheet S that has been transported in the retransport path 202 toward the image forming unit 4. By retransporting the sheet S, on which an image has been formed on one side, toward the image forming unit 4 via the retransport path 202 using the retransport rollers 38 and 39, it is possible to form an image on both sides of the sheet S. In other words, the transport direction in which the retransport rollers 38 and 39 transport the sheet is from rear to front.

[0055] The image forming unit 4 forms an image on the sheet S and is housed within the main body 2 of the device. The image forming unit 4 has a drum cartridge 5 and a laser unit 7. The drum cartridge 5 has a photoreceptor drum 51, a toner storage unit 57, a supply roller 56, a developer 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 2 of the device 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 in accordance with the rotation of the registration roller 35 and transports the sheet S together with the registration roller 35.

[0056] The photoreceptor drum 51 rotates clockwise by the driving force transmitted from the main motor 108 (see Figure 3), thereby transporting the sheet S in the transport direction. In the photoreceptor drum 51, forward rotation, which transports the sheet S in the transport direction, is clockwise. The toner storage section 57 contains toner. The supply roller 56 supplies the toner from the toner storage section 57 to the developing roller 55. The charger 52 is a Scorotron-type charger that uniformly charges the surface of the photoreceptor drum 51. Note that the charger 52 may also be a charging roller.

[0057] A transfer roller 53 is positioned opposite the photoreceptor drum 51. The transfer roller 53 forms a transfer nip TN between itself and the photoreceptor drum 51 in the transport path 201. A transfer belt may be used instead of the transfer roller 53.

[0058] The main body of the device 2 has a laser unit 7 at its upper interior. The laser unit 7 includes a polygon mirror 131 (see Figure 3), a laser light-emitting unit 132 (see Figure 3), lenses and reflectors (not shown), etc. The laser unit 7 exposes the surface of the photoreceptor drum 51 by rapidly scanning the surface of the photoreceptor drum 51 with laser light (see dashed line in Figure 1) based on image data emitted from the laser light-emitting unit 132.

[0059] The surface of the photoreceptor drum 51 is exposed 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 photoreceptor drum 51, thereby forming a toner image on the surface of the photoreceptor drum 51.

[0060] A transfer voltage is applied to the transfer roller 53 by a voltage application unit (not shown). The transfer roller 53 transports the sheet S between itself and the photoreceptor drum 51, thereby transferring the toner image formed on the surface of the photoreceptor drum 51 to the sheet S as it passes through the transfer nip TN. In this way, an image is formed on the sheet S.

[0061] A fuser 6 is located downstream of the image forming unit 4 in the transport path 201. The fuser 6 includes a heating roller 61, a pressure roller 62, a heater 63 (see Figure 3), and a temperature sensor 64 (see Figure 3). The heating roller 61 is an example of a heating rotating body and heats the sheet S. The pressure roller 62 is an example of a pressure rotating body and forms a nip N with the heating roller 61 to pressurize the sheet S. The pressure roller 62 rotates counterclockwise due to the driving force of the main motor 108. For the pressure roller 62, the forward rotation, which is the rotation that transports the sheet S in the transport direction, is counterclockwise. Thus, the pressure roller 62 is a driving roller and the heating roller 61 is a driven roller, but conversely, the heating roller 61 may be a driving roller that rotates clockwise due to the driving force of the main motor 108, and the pressure roller 62 may be a driven roller.

[0062] The heater 63 is, for example, a halogen heater, and heats the heating roller 61. The temperature sensor 64 is located near the heating roller 61 and detects the temperature of the heating roller 61. The temperature sensor 64 outputs a signal corresponding to the detected temperature to the CPU 101 (see Figure 3).

[0063] The fuser 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, and fixing the image formed on the sheet S by the image forming unit 4 to the sheet S.

[0064] The fuser 6 is configured to include a heating roller 61, a pressure roller 62, and a heater 63, but is not limited to these configurations. For example, the fuser 6 may have a heater, a nip plate that receives radiant heat from the heater, a heating belt that rotates around the nip plate, and a pressure roller. Alternatively, the fuser 6 may have a substrate on which a heating pattern is formed, a belt that rotates around the substrate, and a pressure roller, with the substrate and belt in contact. Furthermore, the fuser 6 may have a heating roller, a heater, and a pressure belt.

[0065] In the first discharge path 201A, a cutter 10 is positioned at cutter position B between the first discharge roller 85 and the second discharge roller 86. As will be described later, the printer 1 stops the rotation of the first discharge roller 85 and the second discharge roller 86 so that the cutting position on the sheet S reaches cutter position B. With the rotation of the first discharge roller 85 and the second discharge roller 86 stopped, the printer 1 uses the cutter 10 to cut the sheet S at cutter position B.

[0066] Figure 2 shows a schematic configuration of the cutter 10. As shown in Figure 2, the cutter 10 includes a cutter frame 11, a slide rail 12, a fixed blade 13, a sheet passage section 14, a movable blade 15, a slide holder 16, and a cutting motor 106. The cutter frame 11 extends in the axial direction. The slide rail 12 is a rail formed in the cutter frame 11 that extends in the axial direction. The fixed blade 13 is a flat, plate-shaped blade that extends in the axial direction and is fixed to the cutter frame 11. The sheet passage section 14 is a space formed in the cutter frame 11 through which a sheet S passes. In this embodiment, the sheet passage section 14 is formed between the slide rail 12 and the fixed blade 13. The movable blade 15 is a disc-shaped blade that is rotatably fixed to the slide holder 16.

[0067] The slide holder 16 engages with the slide rail 12 and is mounted on the cutter frame 11 so as to be slidable along the slide rail 12. When the cutting motor 106 is rotated forward, the slide holder 16 slides from one side to the other in the axial direction, and when the cutting motor 106 is reversed, the slide holder 16 slides from the other side to the one side in the axial direction. The slide holder 16 is movable from the initial position shown by the solid line in Figure 2 to the completed cutting position shown by the dashed line. When the sheet S is at cutter position B, and the slide holder 16 moves along the slide rail 12 to the completed cutting position, one sheet S is sandwiched between the fixed blade 13 and the movable blade 15 and cut into two sheets. After cutting the sheet S, the slide holder 16 is returned from the completed cutting position to the initial position before the sheet S is transported toward the discharge tray 22. However, the slide holder 16 may also be configured to return from the cutting completion position to its initial position after discharging the cut sheet S to the discharge tray 22, and before starting to cut the next sheet S.

[0068] The printer 1 is configured to cut A4 and letter-sized sheets S at the center of the sheet in the transport direction using the cutter 10. In other words, the length of the transport path 201 from the nip N to the cutter position B in Figure 1 is designed to be longer than half the dimensions of the A4-sized sheet S in the transport direction (297 mm) (148.5 mm). With this configuration, when cutting an A4 or letter-sized sheet S at the cutter position B with the rotation of the first discharge roller 85 and the second discharge roller 86 stopped, the rear end of the sheet S passes through the nip N of the fuser 6. If the rotation of the first discharge roller 85 and the second discharge roller 86 is stopped in order to cut the sheet S at the cutter position B while the sheet S is held between the nip N of the fuser 6, the rotation of the pressure roller 62 must also be stopped. If the rotation of the pressure roller 62 stops while the sheet S is held between the nip N of the fuser 6, heat will be locally applied to the same spot on the sheet S from the heating roller 61. Therefore, when cutting the sheet S at cutter position B with the rotation of the first discharge roller 85 and the second discharge roller 86 stopped, the rear end of the sheet S must pass through the nip N of the fuser 6.

[0069] Furthermore, the length of the transport path 201 from the nip of roller 36 to cutter position B in Figure 1 is designed to be longer than half the dimension (148.5 mm) of the A4-sized sheet S in the transport direction (297 mm). With this configuration, when cutting the sheet S at cutter position B with the rotation of the first discharge roller 85 and the second discharge roller 86 stopped, the rear end of the sheet S passes through the nip of roller 36. When cutting the sheet S at cutter position B with the rotation of the first discharge roller 85 and the second discharge roller 86 stopped, if the nip of roller 36 or the pressure roller 62 is rotating while gripping the sheet, there is a risk that the sheet S will bend into an accordion shape between the first discharge roller 85 and roller 36. Therefore, with the above configuration, it is possible to stop the sheet at the cutting position without it bending into an accordion shape by only stopping the rotation of the first discharge roller 85 and the second discharge roller 86, without stopping the rotation of roller 36 or the fuser 6.

[0070] Furthermore, the length of the second discharge path 201B is designed to be shorter than the length of the first discharge path 201A. In other words, the second discharge roller 86 is located in front of the third discharge roller 87. This is to allow the sheet S to be quickly discharged to the outside of the device body 2 when the sheet S is not cut after image formation.

[0071] Next, the control configuration of printer 1 will be described with reference to Figure 3. As shown in Figure 3, printer 1 further includes an ASIC 105, ROM 102, RAM 103, NVRAM 104, a post-cash sensor SE2, an ejection sensor SE3, a sheet detection sensor SE4, and a communication interface (I / F) 130.

[0072] The ASIC105 is equipped with a CPU101. The CPU101 is an example of a control unit and performs overall control of each part of the printer 1. The ASIC105 is electrically connected to the ROM102, RAM103, NVRAM104, cutting motor106, flapper88, electromagnetic clutch107, main motor108, ​​ejection motor109, pre-cash register sensor SE1, post-cash register sensor SE2, ejection sensor SE3, sheet detection sensor SE4, operation panel PA, communication I / F130, drum cartridge5, fuser6, and laser unit7.

[0073] ROM102 stores various control programs and settings for controlling printer 1. The printing process, described later using Figure 6, is included in the control program.

[0074] RAM103 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 the job. The CPU101 controls each part of the printer 1 while storing the processing results in RAM103 or NVRAM104 according to the control programs read from ROM102 and signals output from various sensors.

[0075] The CPU 101 drives the cutting motor 106 to move the slide holder 16, thereby moving the movable blade 15 in the width direction of the sheet S and cutting the sheet S.

[0076] The main motor 108 transmits driving force to the pickup roller 33, registration roller 35, roller 36, re-transport rollers 38, 39, pressure roller 62, and drum cartridge 5. When the CPU 101 drives the main motor 108 in the forward direction, the roller 36, pressure roller 62, and drum cartridge 5 are driven. Driving force is transmitted to the pressure roller 62, the photoreceptor drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35. Then, the roller 36, the pressure roller 62, the photoreceptor drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35 rotate in a direction that conveys the sheet S in the transport direction.

[0077] Specifically, the roller 36 and pressure roller 62 rotate counterclockwise. The photoreceptor drum 51 rotates clockwise. The developing roller 55 rotates counterclockwise. The pickup roller 33 rotates counterclockwise. The registration roller 35 rotates counterclockwise.

[0078] On the other hand, even if the CPU 101 reverses the drive of the main motor 108, the drive force is not transmitted to the roller 36, pressure roller 62, drum cartridge 5, pickup roller 33, and registration roller 35.

[0079] Furthermore, the CPU 101 transmits driving force to the re-transport rollers 38 and 39 by driving the main motor 108 in the forward direction, causing them to rotate clockwise. On the other hand, the CPU 101 also transmits driving force to the re-transport rollers 38 and 39 by driving the main motor 108 in the reverse direction, causing the re-transport rollers 38 and 39 to rotate clockwise.

[0080] The discharge motor 109 is, for example, a stepping motor, and transmits driving force to the first discharge roller 85, the second discharge roller 86, and the third discharge roller 87. When the CPU 101 drives the discharge motor 109 in the forward direction, the first discharge roller 85, the second discharge roller 86, and the third discharge roller 87 rotate counterclockwise. As a result, the sheet S is discharged to the discharge tray 22 via the first discharge path 201A or the second discharge path 201B. On the other hand, the CPU 101 drives the discharge motor 109 in the reverse direction, causing the first discharge roller 85, the second discharge roller 86, and the third discharge roller 87 to rotate clockwise. As a result, the sheet S being transported in the second discharge path 201B is transported in the opposite direction to the transport direction.

[0081] The CPU 101 controls the electromagnetic clutch 107. By turning on the electromagnetic clutch 107, the CPU 101 enables the driving force of the main motor 108 to be transmitted to the pickup roller 33, while by turning off the electromagnetic clutch 107, the CPU 101 prevents the driving force of the main motor 108 from being transmitted to the pickup roller 33.

[0082] The CPU 101 controls the flapper 88. The CPU 101 can switch the position of the flapper 88 between a first position (position 88A, shown by a dashed line in Figure 1) and a second position (position 88B, shown by a solid line in Figure 1) by, for example, turning a flapper solenoid (not shown) on or off. The flapper 88 in the first position 88A guides the sheet S conveyed by the roller 36 to the first discharge path 201A. The flapper 88 in the second position 88B guides the sheet S conveyed by the roller 36 to the second discharge path 201B. The flapper 88 in the second position 88B also guides the sheet S in the second discharge path 201B to the re-conveyance path 202.

[0083] The pre-register sensor SE1 is positioned upstream of the registration roller 35 in the transport path 201 and is a sensor that detects when the sheet S passes. The pre-register sensor SE1 has an actuator that swings when the sheet S comes into contact with it, and a photosensor that detects the position of the actuator. The pre-register sensor SE1 outputs an ON signal when the sheet S is passing and an OFF signal when the sheet S is not passing. The detection signal from the pre-register sensor SE1 is output to the CPU 101.

[0084] The post-register sensor SE2 is located upstream of the fuser 6 in the transport path 201, specifically, This sensor is positioned between the registration roller 35 and the transfer roller 53 and detects when the sheet S passes through. The post-register sensor SE2 has the same configuration as the pre-register sensor SE1. The detection signal from the post-register sensor SE2 is output to the CPU 101.

[0085] The discharge sensor SE3 is positioned between the fuser 6 and the roller 36 in the transport path 201 and detects when the sheet S passes through. The discharge sensor SE3 has the same configuration as the pre-cash register sensor SE1. The detection signal from the discharge sensor SE3 is output to the CPU 101.

[0086] The sheet detection sensor SE4 is positioned between the cutter position B and the second discharge roller 86 and detects when a sheet S passes through, as well as the open / closed state of the cover 23 that opens and closes to cover the first discharge path 201A between the first discharge roller 85 and the second discharge roller 86. The sheet detection sensor SE4 outputs an ON signal when the cover 23 is open and when the cover 23 is closed and a sheet S is passing through, and outputs an OFF signal when the cover 23 is closed and a sheet S is not passing through.

[0087] Figure 5 shows the operation of the sheet detection sensor SE4. Figure 5(a) shows the case when the cover 23 is open, Figure 5(b) shows the case when the cover 23 is closed and the sheet S is not passing through, and Figure 5(c) shows the case when the cover 23 is closed and the sheet S is passing through. As shown in Figure 5, the sheet detection sensor SE4 is an actuator-type photosensor and has an actuator 120 and a transmissive photosensor 121. The transmissive photosensor 121 has a light-emitting part 121A and a light-receiving part (not shown). When the optical path irradiated from the light-emitting part 121A to the light-receiving part is blocked by the actuator 120, it outputs an off signal (an example of a second signal), and when the optical path is not blocked, it outputs an on signal (an example of a first signal).

[0088] The actuator 120 has a first arm portion 120A and a second arm portion 120B. The first arm portion 120A and the second arm portion 120B are formed in a V-shape when viewed from the side, i.e., in the left-right direction, and are rotatable clockwise and counterclockwise around a rotation axis (not shown) in the left-right direction. When the cover 23 shown in Figure 5(a) is in the open state, the first arm portion 120A of the actuator 120 is separated from the cover 23, so the actuator 120 rotates to its maximum extent counterclockwise by a biasing force, such as a spring. At this time, the optical path of the transmissive photosensor 121 is not obstructed by the actuator 120, so the sheet detection sensor SE4 outputs an ON signal. Also, when the cover 23 shown in Figure 5(b) is in the closed state and the sheet S is not passing through, the cover 23 and the upper end of the first arm portion 120A of the actuator 120 come into contact, so the actuator 120 rotates more clockwise than when the cover 23 is in the open state. At this time, the optical path of the transmissive photosensor 121 is blocked by the second arm portion 120B of the actuator 120, so the sheet detection sensor SE4 outputs an off signal. Also, when the cover 23 shown in Figure 5(c) is closed and the sheet S is passing through, the first arm portion 120A of the actuator 120 comes into contact with the sheet S, so the actuator 120 rotates further clockwise. At this time, the optical path of the transmissive photosensor 121 is no longer blocked by the second arm portion 120B of the actuator 120, so the sheet detection sensor SE4 outputs an on signal. The sheet detection sensor may also be, for example, an optical sensor without an actuator that emits light toward the transport path and receives reflected light, and determines whether or not a sheet is in that position by emitting different signals depending on whether or not there is a sheet in the transport path.

[0089] Returning to Figure 3, the control panel PA is located on the top surface of the main body 2 of the device. The control panel PA has, for example, a touch panel in which a touchpad and display are integrally formed, and a key button section. The control panel PA receives user input and outputs the received information to the CPU 101. The user can, for example, set whether or not to cut the sheet S by operating the control panel PA.

[0090] The communication interface 130 is connected to a network such as a LAN and enables connection to external devices such as a PC with a driver for printer 1 installed. The CPU 101 can receive print jobs via the communication interface 130. A print job includes various information necessary for forming an image on the sheet S, such as image data for image formation, the size and type of the sheet S used for image formation, and information on whether or not to cut the sheet S.

[0091] The control processes performed by printer 1, configured as described above, will be explained in detail below with reference to Figures 6 to 13.

[0092] Figure 6 shows the steps of the printing process executed by the ASIC105, particularly the CPU101. This printing process is executed when printer 1 is able to receive print jobs or print commands, for example, when printer 1 is powered on or when printer 1 is in standby mode. Hereafter, each step will be denoted as "S" in the description of each process.

[0093] In Figure 6, the CPU 101 first waits until it receives a print job via the communication interface 130 or a print command via the control panel PA (either S10 or S12: NO). Once it receives a print job or a print command (either S10 or S12: YES), the CPU 101 proceeds to S14.

[0094] In S14, the CPU 101 determines whether or not it is necessary to cut the sheet S to be printed. In this embodiment, this determination is made based on information included in the print job or print command regarding whether or not to cut the sheet S. In other words, if the user has set a mode that specifies cutting the sheet S when setting up the print job, or when setting up a print command via the operation panel PA, then the print job or print command will contain information that the sheet S should be cut. If cutting the sheet S is necessary (S14: YES), the CPU 101 proceeds to S16. On the other hand, if cutting the sheet S is not necessary (S14: NO), the CPU 101 proceeds to S20.

[0095] In S16, the CPU 101 moves the flapper 88 to the first position 88A. The first position 88A is the position that guides the sheet S, which has been conveyed by the roller 36, to the first discharge path 201A, as described above. Next, the CPU 101 performs the sheet printing and cutting process (S18), and then terminates the printing process.

[0096] Meanwhile, in S20, the CPU 101 moves the flapper 88 to the second position 88B. The second position 88B is the position that guides the sheet S, which has been conveyed by the roller 36, to the second discharge path 201B, as described above. Next, the CPU 101 performs normal printing (S22) and then terminates the printing process. In this embodiment, normal printing means printing an image onto the sheet S based on a print job or print command, and then discharging the sheet S to the discharge tray 22 without cutting it.

[0097] Figure 7 shows the detailed procedure for the sheet printing and cutting process in S18. In Figure 7, the CPU 101 first performs a process to determine the number of sheet transport steps based on the set sheet length (S30). Figure 8 shows the detailed procedure for this process to determine the number of sheet transport steps based on the set sheet length.

[0098] In Figure 8, the CPU 101 acquires sheet size information included in the print job or print command (S70). Specifically, sheet size information is information such as "A4 size" or "Letter size". Then, the CPU 101 determines the "sheet cutting position at the time the sheet detection sensor switches from off to on" that corresponds to the acquired sheet size information. After obtaining the number of steps required for the discharge motor to reach the "cutter position" (S72), the process of determining the number of sheet transport steps based on the set sheet length is terminated. More specifically, the ROM 102 or NVRAM 104 stores the number of steps required for the discharge motor to reach the "cutter position" from the corresponding "sheet cutting position when the sheet detection sensor is turned on from off" for each sheet size. For example, if the sheet size information is A4, the CPU 101 obtains the number of steps corresponding to A4 stored in the ROM 102 or NVRAM 104.

[0099] In Figure 4(a), the cutting position CP of the sheet S is the center position of the sheet length L in the transport direction. Therefore, in the process of S72, the CPU 101 obtains the number of steps required for the discharge motor 109 to reach the cutter position B from the cutting position CP of the sheet S, i.e., the center position, at the time when the sheet detection sensor SE4 is turned on from off, i.e., when the front end of the sheet S is detected. Since this number of steps is a fixed value according to the sheet size of the sheet S, the number of steps associated with the sheet size information can be stored in advance in the NVRAM 104, for example, by factory settings. In this case, in S72, the CPU 101 reads and obtains the number of steps corresponding to the sheet size information obtained in S70 from the NVRAM 104.

[0100] Returning to Figure 7, the CPU 101 drives the main motor 108 in the forward direction (S32). At this time, the CPU 101 also turns on the heater 63.

[0101] Next, the CPU 101 executes a pickup command (S34). This causes the CPU 101 to turn on the electromagnetic clutch 107. When the electromagnetic clutch 107 is turned on, as described above, the driving force of the main motor 108 is transmitted to the pickup roller 33, so that the sheet S in the supply tray 31 is picked up and transported toward the transport path 201.

[0102] Next, the CPU 101 waits until the post-registration sensor SE2 switches from off to on (S36: NO). As described above, the post-registration sensor SE2 is positioned between the registration roller 35 and the transfer roller 53 in the transport path 201, and outputs an ON signal when the sheet S is passing and an OFF signal when the sheet S is not passing. Therefore, in S36, the CPU 101 waits until the post-registration sensor SE2 detects the front edge of the sheet S. When the post-registration sensor SE2 detects the front edge of the sheet S (S36: YES), the CPU 101 starts image formation on the sheet S (S38). Note that image formation may be started by triggers other than the post-registration sensor SE2 detecting the front edge of the sheet S. Image formation should be performed in such a way that the toner image formed by the photoreceptor drum 51 is correctly transferred to the image formation position on the sheet S.

[0103] Next, the CPU 101 waits until the discharge sensor SE3 switches from off to on (S40: NO). As described above, the discharge sensor SE3 is positioned between the fuser 6 and the roller 36 in the transport path 201, and outputs an ON signal when the sheet S is passing and an OFF signal when the sheet S is not passing. Therefore, in S40, the CPU 101 waits until the discharge sensor SE3 detects the front end of the sheet S. When the discharge sensor SE3 detects the front end of the sheet S (S40: YES), the CPU 101 drives the discharge motor 109 in the forward direction (S42). As a result, the first to third discharge rollers 85 to 87 begin to rotate.

[0104] Next, the CPU 101 determines whether the sheet detection sensor SE4 has switched from off to on (S44). As described above, the sheet detection sensor SE4 is positioned between the cutter position B and the second discharge roller 86 in the transport path 201, and outputs an ON signal when the sheet S is passing through and an OFF signal when the sheet S is not passing through. As mentioned above, the sheet detection sensor SE4 outputs an ON signal even when the cover 23 is open, but this case is not considered here. Therefore, in S44, the CPU 101 determines whether or not the sheet detection sensor SE4 has detected the front edge of the sheet S. If the sheet detection sensor SE4 does not detect the front edge of the sheet S (S44: NO), the CPU 101 determines whether or not a predetermined time has elapsed (S46). If the predetermined time has not elapsed (S46: NO), the CPU 101 returns to processing S44. On the other hand, if the predetermined time has elapsed (S46: YES), the CPU 101 executes error stop processing due to a JAM (S48) and then terminates the sheet printing and cutting process. Here, "predetermined time" is the time that is calculated by adding a predetermined margin to the normal time it takes from when the discharge motor 109 is driven in the forward direction until the sheet detection sensor SE4 detects the front edge of the sheet S. In other words, if the sheet detection sensor SE4 does not detect the front end of sheet S after this time has elapsed, it can be determined that sheet S is in a jammed state on the transport path 201.

[0105] Figure 12 shows the detailed procedure for error shutdown due to a jam. In Figure 12, the CPU 101 stops the ejection motor 109 (S120), the main motor 108 (S122), and other devices (S124). Other devices include the image forming unit 4 and the fuser 6. Then, the CPU 101 displays a notification screen (not shown) on the operation panel PA indicating that a jam has occurred (S126), and then terminates the error shutdown process due to the jam. Preferably, the notification screen also displays information indicating where the jam occurred, in addition to the fact that a jam has occurred.

[0106] Returning to Figure 7, in the determination at S44, if the sheet detection sensor SE4 detects the front edge of sheet S (S44: YES), the CPU 101 executes the sheet transport process to the cutter position (S50). Figure 9 shows the detailed procedure for the sheet transport process to the cutter position.

[0107] In Figure 9, the CPU 101 starts measuring the number of steps of the discharge motor 109 (S80). As described above, the discharge motor 109 is a stepping motor, so the CPU 101 can easily measure the number of steps of the discharge motor 109 simply by counting the pulses input to the motor driver (not shown) of the discharge motor 109. The number of steps can be measured, for example, by counting up a step count measurement area (not shown) allocated in the RAM 103.

[0108] Next, the CPU 101 waits until it has counted the number of steps acquired in S72 (Figure 8) (S82: NO), and once the counting of the number of steps is complete (S82: YES), the CPU 101 stops the discharge motor 109 (S84). As a result, the sheet S stops with its cutting position CP reaching the cutter position B. Alternatively, the CPU 101 may be configured to use the number of steps acquired in S72 as an initial value, count down with each pulse input to the motor driver of the discharge motor 109, and stop the discharge motor 109 when the remaining number of steps becomes zero.

[0109] Returning to Figure 7, the CPU 101 executes the sheet cutting process (S52). Figure 10 shows the detailed procedure of the sheet cutting process. In Figure 10, the CPU 101 drives the cutting motor 106 in the forward direction (S90). This moves the moving blade 15 in a direction that contacts the sheet S, and the cutting of the sheet S begins. Next, the CPU 101 determines whether the moving blade 15 has reached the cutting completion position (S92). In other words, it determines whether the cutting of the sheet S is complete. If, for example, an encoder-equipped DC motor is used as the cutting motor 106, the encoder outputs signals indicating the rotation direction, rotation position, and rotation speed corresponding to the rotation of the cutting motor 106, so the CPU 101 can determine whether the moving blade 15 has reached the cutting completion position based on these signals. In the determination in S92, if the moving blade 15 cuts... If the completion position has not been reached (S92: NO), the CPU 101 determines whether the sheet detection sensor SE4 has switched from on to off (S100). If the sheet detection sensor SE4 remains on (S100: NO), the CPU 101 returns to processing S92. On the other hand, if the sheet detection sensor SE4 has switched from on to off (S100: YES), the CPU 101 determines that the sheet S being cut has been pulled out of the first discharge path 201A, executes error stop processing due to sheet pull-out detection (S102), and then terminates the sheet cutting process.

[0110] Figure 11 shows the detailed procedure for error stop processing due to sheet pull-out detection. In Figure 11, the CPU 101 performs the same processing as in S120 to S124 in S110 to S114, that is, processing to stop the discharge motor 109, the main motor 108 and other devices. Then, the CPU 101 displays a notification screen (not shown) indicating sheet pull-out on the operation panel PA (S126), and then terminates the error stop processing due to sheet pull-out detection.

[0111] Returning to Figure 10, in the judgment at S92, if the moving blade 15 has reached the cutting completion position (S92: YES), the CPU 101 stops the cutting motor 106 (S94) and then drives it in reverse (S96). As a result, the moving blade 15 starts moving from the cutting completion position shown by the dashed line in Figure 2 toward the initial position shown by the solid line. The CPU 101 then determines whether the moving blade 15 has reached the initial position (S98), and if it has not reached the initial position (S98: NO), it performs the same processing as in S100 and S102 in S104 and S106. In other words, the CPU 101 determines whether the sheet S has been pulled out of the first discharge path 201A while the moving blade 15 is returning to the initial position, and if it has been pulled out (S104: YES), it executes an error stop process due to sheet pull-out detection.

[0112] On the other hand, in the judgment of S98, if the moving blade 15 reaches its initial position (S98: YES), the CPU 101 terminates the sheet cutting process.

[0113] Returning to Figure 7, the CPU 101 drives the discharge motor 109 in the forward direction (S54). As a result, the sheet S cut at the cutting position CP begins to be transported toward the discharge tray 22. Next, the CPU 101 determines whether the sheet detection sensor SE4 has switched from on to off (S56). In other words, it determines whether the discharge of the sheet S toward the discharge tray 22 is complete. If the sheet detection sensor SE4 does not switch from on to off after a predetermined time has elapsed (S58: YES), that is, if the sheet S remains in the first discharge path 201A, the CPU 101 determines that the sheet S is in a JAM state and performs the same JAM error stop process as in S48 (S60), and then terminates the sheet printing and cutting process.

[0114] On the other hand, in the judgment of S56, if the sheet detection sensor SE4 switches from on to off (S56: YES), the discharge motor 109 is stopped after a predetermined time has elapsed (S62). As a result, the sheet S, which has been divided into two equal parts, is discharged into the discharge tray 22. Therefore, the "predetermined time" is the time it takes for the sheet on the upstream side in the transport direction of the divided sheet S to be discharged from the first discharge path 201A into the discharge tray 22.

[0115] Next, the CPU 101 determines whether or not the currently running job requires printing of the next sheet (S64). If the determination indicates that there is printing for the next sheet (S64: YES), the CPU 101 returns to processing S34 and continues processing from S34 onward. On the other hand, if there is no printing for the next sheet (S64: NO), the CPU 101 stops the main motor 108 (S66) and then terminates the sheet printing and cutting process.

[0116] Next, the cover open state detection process will be explained. The sheet detection sensor SE4 is as described above. The device outputs an ON signal when the cover 23 is open and when the cover 23 is closed and the sheet S is passing through, and an OFF signal when the cover 23 is closed and the sheet S is not passing through. The cover open state detection process is a process that detects the open state of the cover 23 based on the output result of the sheet detection sensor SE4.

[0117] Figure 13 shows the procedure for the cover open state detection process executed by the CPU 101. The cover open state detection process is started in parallel with the printing process (Figure 6), for example, when the printer 1 is powered on or when the printer 1 is in standby mode.

[0118] In Figure 13, the CPU 101 determines whether the sheet detection sensor SE4 has switched from off to on when there are no sheets S being processed in the first discharge path 201A (S130, S132). In this determination, if the sheet detection sensor SE4 has switched from off to on when there are no sheets S being processed in the first discharge path 201A (S130 and S132: YES), the CPU 101 determines that the cover 23 is in the open state (S134), and displays a notification screen (not shown) indicating that the cover 23 is in the open state on the operation panel PA (S136), after which the cover open state detection process ends.

[0119] The sheet detection sensor SE4 outputs an ON signal when the cover 23 is open and when the cover 23 is closed and the sheet S is passing through. Therefore, in order to determine that the cover 23 is open, it is necessary to exclude the case when the cover 23 is closed and the sheet S is passing through. In other words, in S130, if there is no sheet S being processed in the first discharge path 201A, the sheet detection sensor SE4 will not be turned ON by the passage of the sheet S, so it is determined that the sheet detection sensor SE4 was not turned ON by the passage of the sheet S. Then, in S132, it is determined that the sheet detection sensor SE4 was not turned ON by the passage of the sheet S, but rather by the cover 23 being opened.

[0120] As described above, the printer 1 of this embodiment is characterized by comprising: a device body 2 having a sheet transport path 201 for sheet S; a fuser 6 having a heating roller 61 and a pressure roller 62 that forms a nip N between itself and the heating roller 61, for fixing an image formed on sheet S to sheet S; a first discharge roller 85 located downstream of the fuser 6 in the transport direction of sheet S along the transport path 201 for transporting sheet S; a second discharge roller 86 located downstream of the first discharge roller 85 in the transport direction for discharging sheet S transported by the first discharge roller 85 to the outside of the device body 2; a cutter 10 located at cutter position B, which is between the first discharge roller 85 and the second discharge roller 86 in the transport direction, capable of cutting sheet S in a cutting direction intersecting the transport direction; and a sheet detection sensor SE4 that detects whether or not sheet S is present at a first detection position between the first discharge roller 85 and the second discharge roller 86 in the transport direction.

[0121] Thus, in the printer 1 of this embodiment, the cutter 10 is positioned between the first discharge roller 85 and the second discharge roller 86 in the transport direction, and the presence or absence of a sheet S at a detection position between the first discharge roller 85 and the second discharge roller 86 is detected in a similar manner, making it possible to accurately detect the sheet S around the cutter 10.

[0122] Incidentally, in this embodiment, the heating roller 61 is an example of a "heating rotating body". The pressure roller 62 is an example of a "pressure rotating body". The sheet detection sensor SE4 is an example of a "first sensor".

[0123] Furthermore, printer 1 is equipped with a CPU 101. The CPU 101 determines, based on the output of the sheet detection sensor SE4, when the front edge of the sheet S reaches a first detection position. The system is characterized by driving the first discharge roller 85 and the second discharge roller 86 for a number of steps required to transport the sheet S until the cutting position of the sheet S reaches the cutter position B, then stopping the transport of the sheet S, and after the transport process, cutting the sheet S in the cutting direction using the cutter 10. Incidentally, the CPU 101 is an example of a "control unit". The number of steps is an example of a "drive amount".

[0124] In this way, the sheet S is transported based on the output of the sheet detection sensor SE4 located near the cutter position B until the cutting position CP of the sheet S reaches the cutter position B, and the sheet S is cut at that transport position. This makes it possible to accurately cut the sheet S at the cutting position CP.

[0125] Furthermore, the CPU 101 receives a print job that includes the sheet size of the sheet S, and executes a drive amount acquisition process that obtains the number of steps based on the sheet size included in the received print job. In the transport process, it drives the first discharge roller 85 and the second discharge roller 86 with the number of steps obtained by the step number acquisition process, and then stops the transport of the sheet S.

[0126] This makes it possible to obtain the number of steps for the ejection motor 109 based on the sheet size, which is simple information included in the received print job, thus simplifying the process of obtaining the number of steps.

[0127] Furthermore, the printer 1 is further equipped with an ejection motor that drives the first ejection roller 85 and the second ejection roller 86. The CPU 101 is characterized in that, during the transport process, if the sheet detection sensor SE4 does not detect the sheet S even after a predetermined time has elapsed since the ejection motor 109 was started to drive, it stops the operation of the ejection motor 109.

[0128] This makes it possible to accurately detect jams in the sheet S during transport and to perform appropriate error handling in response to the jams.

[0129] The printer 1 also includes a main motor 108 that rotates either the heating roller 61 or the pressure roller 62. The CPU 101 is characterized in that, during the transport process, if the sheet detection sensor SE4 does not detect the sheet S even after a predetermined time has elapsed since the discharge motor 109 was started, it also stops the main motor 108.

[0130] This makes it possible to perform error handling more accurately in response to jams.

[0131] The main unit 2 of the device further includes a display panel, and the CPU 101 is characterized in that, during the transport process, if the sheet detection sensor SE4 does not detect the sheet S even after a predetermined time has elapsed since the discharge motor 109 was started to drive, it will display a notification screen on the operation panel PA indicating that a jam has occurred.

[0132] This makes it possible to accurately notify the user of any jams occurring in the sheet S during the transport process.

[0133] The printer 1 also includes an ejection motor 109 that drives the first ejection roller 85 and the second ejection roller 86. The CPU 101 then drives the first ejection roller 85 and the second ejection roller 86 after the cutting process to perform an ejection process that ejects the cut sheet S to the outside of the device body 2. During the ejection process, if the sheet detection sensor SE4 detects the sheet S even after a predetermined time has elapsed since the start of driving the ejection motor 109, the ejection motor The characteristic feature is that it stops the drive of the Ta 109.

[0134] This makes it possible to accurately detect jamming of sheet S during the discharge process after cutting and to perform appropriate error processing in response to the jamming.

[0135] Furthermore, the main unit 2 of the device further includes an operation panel PA, and the CPU 101 is characterized in that, during the discharge process, if the sheet detection sensor SE4 does not detect the sheet S even after a predetermined time has elapsed since the discharge motor 109 was started to drive, it will display a notification screen on the operation panel PA indicating that a jam has occurred. Incidentally, the operation panel PA is an example of a "display panel".

[0136] This makes it possible to accurately notify the user of any jamming that occurs in the sheet S during the discharge process after cutting.

[0137] Furthermore, the cutter 10 includes a movable blade 15 for cutting the sheet S and a cutting motor 106 for moving the movable blade 15 in the cutting direction. The CPU 101 is characterized in that, during the cutting process, when the cutting motor 106 is running and the discharge motor 109 is not running, if the sheet detection sensor SE4 changes from a state of detecting the sheet S to a state of not detecting it, the CPU 101 stops the driving of the cutting motor 106. Incidentally, the movable blade 15 is just one example of a "blade".

[0138] This makes it possible to accurately determine if sheet S has been pulled out during the cutting process and to perform appropriate error handling accordingly.

[0139] Furthermore, the sheet detection sensor SE4 is characterized by detecting whether or not a sheet S is present at the detection position between the cutter 10 and the second discharge roller 86.

[0140] This makes it possible to accurately detect the sheet S around the cutter 10.

[0141] The printer 1 also includes a cover 23 that can be opened and closed to cover the transport path 201 between the first discharge roller 85 and the second discharge roller 86. The sheet detection sensor SE4 outputs an ON signal when the cover 23 is open and when the cover 23 is closed and a sheet S is detected, and outputs an OFF signal when the cover 23 is closed and a sheet S is not detected. The CPU 101 determines that the cover 23 is open when the sheet detection sensor SE4 outputs an ON signal while the sheet S is not being transported by the first discharge roller 85 and the second discharge roller 86. The ON signal is an example of a "first signal". The OFF signal is an example of a "second signal".

[0142] This allows a single sheet detection sensor SE4 to handle both the detection of sheet S and the detection of the open state of cover 23, thereby reducing the overall manufacturing cost of printer 1.

[0143] Furthermore, the printer 1 is equipped with a third discharge roller 87 located in a second discharge path 201B that branches off from the transport path 201 between the fuser 6 and the first discharge roller 85. This third discharge roller 87 is located at a position shorter than the length of the transport path 201 from the fuser 6 to the second discharge roller 86, and discharges the sheet S to the outside of the device body 2. The CPU 101 receives a print job that includes cut information indicating whether or not to cut the sheet S. If the cut information included in the received print job indicates not to cut, the CPU 101 transports the sheet S using the third discharge roller 87 and discharges the sheet S from the device body 2 to the outside without cutting it. This is characterized by the following. Incidentally, a print job is an example of "print data". The second discharge route 201B is an example of a "discharge route".

[0144] As a result, when the sheet S is not cut, it is discharged to the outside of the device body 2 via a shorter path in the transport path 201, making it possible to quickly discharge the uncut sheet S to the outside of the device body 2.

[0145] Furthermore, the printer 1 is equipped with a flapper 88 that can be switched between a first position 88A that guides the sheet S toward the first discharge roller 85 and a second position 88B that guides the sheet S toward the third discharge roller 87. The CPU 101 is characterized in that, if the cutting status information indicates that cutting should be performed, the CPU 101 switches the flapper 88 to the first position 88A after the front end of the sheet S has left the fuser 6 but before it reaches the flapper 88, and if the cutting status information indicates that cutting should not be performed, the CPU 101 switches the flapper 88 to the second position 88B after the front end of the sheet S has left the fuser 6 but before it reaches the flapper 88.

[0146] This is convenient because, based on the cutting information included in the print job, the sheet S is automatically guided toward either the first discharge roller 85 or the third discharge roller 87.

[0147] Furthermore, the length of the transport path 201 from the fuser 6 to the cutter 10 is longer than half the length of the sheet in the transport direction of the sheet that can be cut.

[0148] As a result, when cutting the sheet S at cutter position B, the state in which the sheet S is pinched by the nip N of the fuser 6 is eliminated, making it possible to suppress the application of heat to the sheet S from the heating roller 61 when the rotation of the pressure roller 62 has stopped. In this embodiment, the length is the length in the transport direction from the downstream end of the nip N of the fuser 6 in the transport direction to the fixed blade 13 of the cutter 10, but for example, it may be the length in the transport direction from the downstream end of the outer circumference of the pressure roller 62 or heating roller 61 of the fuser 6 in the transport direction to the fixed blade 13 of the cutter 10.

[0149] Furthermore, the printer 1 further includes an ejection motor 109 that drives the first ejection roller 85, a roller 36 located between the first ejection roller 85 and the fuser 6, and a main motor 108 that drives the roller 36 and the fuser 6. The length of the transport path 201 from the roller 36 to the cutter 10 is longer than half the length of the sheet S in the transport direction, and the CPU 101 keeps the main motor 108 running during the cutting process.

[0150] This makes it possible to keep the sheet S in place at cutter position B by stopping only the discharge motor 109 without stopping the main motor 108 from driving the rollers 36 and the fuser 6 when cutting the sheet S at cutter position B.

[0151] (Second Embodiment) Next, a second embodiment of the present invention will be described. This embodiment is constructed by modifying a part of the sheet printing and cutting process (see Figure 7) described in the first embodiment, so the description will focus on the modified parts, and the description of other parts will be omitted as appropriate. Furthermore, the hardware of this embodiment will be the same as the hardware shown in Figures 1 to 3.

[0152] Figure 14 shows the procedure for the sheet printing and cutting process performed by the ASIC 105, particularly the CPU 101, of the printer 1 in this embodiment. In the sheet printing and cutting process in Figure 7, the cutting position CP of the sheet S is determined by the sheet transport step number determination process (S30) based on the set sheet length. In the first case, the number of steps for the discharge motor 109 to reach cutter position B is determined. In contrast, the sheet printing and cutting process in Figure 14 differs in that the number of steps for the discharge motor 109 to reach cutter position B is determined by a sheet transport step number determination process (S146) based on the measured sheet length. Therefore, in Figure 14, the same reference numerals are used for processes similar to those in Figure 7, and their explanations are omitted as appropriate.

[0153] When the post-cash sensor SE2 detects the front end of sheet S (S36:YES), the CPU 101 starts measuring the sheet length of sheet S (S140). Since the sheet length is measured by time, the CPU 101 can do this by, for example, counting up a timer area (not shown) reserved in RAM 103 at predetermined time intervals (for example, every 0.01 seconds). In this case, in S140, CPU101 starts counting up the timer area.

[0154] Next, after executing the processes in S38 to S42, the CPU 101 waits until the post-register sensor SE2 detects the rear end of sheet S (S142: NO). When the post-register sensor SE2 detects the rear end of sheet S (S142: YES), the CPU 101 terminates the measurement of the sheet length of sheet S (S144). In other words, the CPU 101 terminates the timer count-up.

[0155] Next, the CPU 101 performs a process to determine the number of sheet transport steps based on the measured sheet length (S146). Figure 15 shows the detailed procedure for determining the number of sheet transport steps based on the measured sheet length. In Figure 15, the CPU 101 acquires the measured sheet length information (S150). In this embodiment, the measured sheet length information is a count value in the timer area, so the CPU 101 reads the count value from the timer area to acquire it.

[0156] Next, the CPU 101 calculates the number of steps required for the discharge motor to reach the cutter position from the sheet cutting position when the sheet detection sensor switches from off to on, based on the acquired measured sheet length information (S152), and then terminates the sheet transport step count determination process based on the measured sheet length.

[0157] Figure 16 is a diagram illustrating the sheet cutting position determination process based on the measured sheet length in Figure 15. As shown in Figure 16, the CPU 101 calculates the sheet length L of the sheet S by the number of steps of the discharge motor 109 using the following equation (1). L(STEP)=T(s)×V(mm / s) / D(mm / STEP) ‥‥(1) however, T: Time elapsed from the time the post-register sensor SE2 detects the front end of sheet S until the time the rear end of sheet S is detected = Timer area count value × Time per count; V: The conveying speed at which the main motor 108 conveys the sheet S; D: Conveying distance per step of discharge motor 109; That is the case.

[0158] If the cutting position CP of sheet S is in the middle of the sheet length, then the number of steps from the sheet detection sensor SE4 to the cutting position CP is L / 2. Furthermore, since the cutter position B is located 20 steps upstream from the detection position of the sheet detection sensor SE4, the number of steps calculated in S152 = L / 2 - 20 (STEP).

[0159] Therefore, when the CPU 101 executes the sheet transport process to the cutter position (S50 in Figure 14), the sheet S stops with the cutting position CP having reached the cutter position B.

[0160] As described above, the printer 1 of this embodiment detects whether or not a sheet S is present at a second detection position which is upstream of the sheet detection sensor SE4 in the transport direction. The system is further equipped with a sensor SE2. The CPU 101 detects, based on the output of the post-register sensor SE2, when the front end of the sheet S has reached the second detection position and when the rear end of the sheet S has reached the second detection position. Based on the detected front and rear ends of the sheet S, the CPU 101 performs a sheet length acquisition process to obtain the sheet length in the conveying direction of the sheet S, and a drive amount acquisition process to obtain the number of steps based on the sheet length obtained by the sheet length acquisition process. In the conveying process, the CPU 101 drives the first discharge roller 85 and the second discharge roller 86 with the number of steps obtained by the step number acquisition process, and then stops the conveying of the sheet S. Incidentally, the post-register sensor SE2 is an example of a "second sensor".

[0161] This allows the number of steps to be obtained based on the measured sheet length of sheet S, so even if sheet S shrinks and its length becomes shorter than the original sheet length, it becomes possible to accurately cut sheet S at the intended cutting position.

[0162] Furthermore, in the sheet length acquisition process, the CPU 101 is characterized by acquiring the sheet length in the conveying direction of the sheet S based on the amount of sheet S conveyed from the detection of the front end of sheet S to the detection of the rear end of sheet S, based on the output of the post-register sensor SE2.

[0163] This allows the sheet length of sheet S to be obtained based on the output of the post-register sensor SE2 already installed in printer 1, thereby reducing the overall manufacturing cost of printer 1.

[0164] It should be noted that the present invention is not limited to the embodiments described herein, and various modifications are possible without departing from the spirit of the invention.

[0165] (1) In each embodiment, the detection positions where the pre-cash register sensor SE1, post-cash register sensor SE2, discharge sensor SE3, and sheet detection sensor SE4 detect the passage of the sheet S are approximately the same as the installation positions of the sensors. However, sensors may be used in which the installation position of the sensor and the detection position of the sheet S are far apart.

[0166] (2) In each embodiment, the sheet detection sensor SE4 is placed between the cutter position B and the second discharge roller 86, but it is not limited to this and may be placed between the first discharge roller 85 and the cutter position B.

[0167] (3) In each embodiment, a monochrome laser printer 1 was described as an example of an image forming apparatus, but the apparatus is not limited to this, and a color laser printer may also be used.

[0168] (4) In each embodiment, the case in which sheet P is cut into two equal parts has been described, but the invention is not limited to this, and sheet P may be cut into, for example, three equal parts.

[0169] (5) In each embodiment, when a print job is received from outside the printer 1, it is received via the communication I / F 130, but the invention is not limited to this, and for example, the print job may be received via the USB interface.

[0170] (6) In each embodiment, the opening / closing detection of the cover 23 and the sheet detection were both performed by the sheet detection sensor SE4, but separate detection sensors may be used.

[0171] (7) In each embodiment, if the sheet detection sensor SE4 does not detect a sheet even after a predetermined time has elapsed since the discharge motor 109 was started to drive, it was determined to be a jam. However, the configuration may be such that no such determination is made. For example, the output of the sheet detection sensor SE4 may be used only to transport the sheet S until the cutting position CP of the sheet S reaches the cutter position B. Alternatively, the output of the sheet detection sensor SE4 may not be used to transport the sheet S until the cutting position CP of the sheet S reaches the cutter position B. Instead, the sheet detection sensor SE4 may be used only to determine that there is a jam if the sheet detection sensor SE4 does not detect the sheet even after a predetermined time has elapsed since the start of driving the discharge motor 109.

[0172] (8) In each embodiment, the printer 1 was configured to be able to cut A4 size and letter size sheets S in the middle of the sheet, but for example, A4 size sheets may not be cut and only letter size sheets S may be cut. In that case, the length of the transport path 201 from the nip N to the cutter position B in Figure 1 and the length of the transport path 201 from the nip of the roller 36 to the cutter position B are half the dimension of the letter size in the transport direction (279.4 mm) It just needs to be designed to be longer than 139.7mm. Furthermore, it should be larger than A4 size. The large-sized sheets may be made cuttable.

[0173] (9) In each embodiment, the cutter 10 was composed of a movable blade 15 and a fixed blade 13, but its shape and type are not limited as long as it can cut the sheet S. For example, it may be a configuration in which the sheet is cut by dropping a blade that is long in the cutting direction onto the sheet S, or it may be scissors. [Explanation of Symbols]

[0174] 1...Printer, 2...Main unit, 6...Fuser, 10...Cutter, 61...Heating roller, 62...Pressure roller, 85...First discharge roller, 86...Second discharge roller, 87...Third discharge roller, 88...Flapper, 101...CPU, 102...ROM, 103...RAM, 104...NVRAM, 105...ASIC, 108...Main motor, 109...Discharge motor, 201...Conveyor path, 201A...First discharge path, 201B...Second discharge path, B...Cutter position, SE3...Discharge sensor, SE4...Sheet detection sensor.

Claims

1. A device body having a sheet transport path, A fixing device comprising a heating rotating body and a pressurizing rotating body that forms a nip between itself and the heating rotating body, for fixing an image formed on the sheet to the sheet, In the conveying direction of the sheet along the aforementioned conveying path, a first discharge roller is located downstream of the fuser and conveys the sheet, A second discharge roller is located downstream of the first discharge roller in the conveying direction and discharges the sheet conveyed by the first discharge roller to the outside of the device body, A cover that can be opened and closed to cover the transport path between the first discharge roller and the second discharge roller, A cutter is positioned at a cutter position between the first discharge roller and the second discharge roller in the conveying direction, and is capable of cutting the sheet in a cutting direction intersecting the conveying direction. A first sensor for detecting whether or not the sheet is present at a first detection position between the first discharge roller and the second discharge roller in the conveying direction, Control unit and Equipped with, The first recall was, The first signal is output when the cover is open, when the cover is closed and the sheet is detected, and the second signal is output when the cover is closed and the sheet is not detected. The control unit, When the sheet is not being transported by the first discharge roller and the second discharge roller, if the first signal is output from the first sensor, it is determined that the cover is in the open state. An image forming apparatus characterized by the following features.

2. The control unit is Based on the output of the first sensor, the first discharge roller and the second discharge roller are driven with the amount of drive required to transport the sheet from when the front end of the sheet reaches the first detection position until the cutting position of the sheet reaches the cutter position, and then the transport of the sheet is stopped. After the conveying process, a cutting process is performed in which the sheet is cut in the cutting direction using the cutter, Execute The image forming apparatus according to feature 1.

3. The control unit, The process involves receiving print data including the sheet size of the aforementioned sheet, and executing a drive amount acquisition process to acquire the drive amount based on the sheet size included in the received print data, In the aforementioned transport process, the first discharge roller and the second discharge roller are driven by the drive amount obtained in the drive amount acquisition process, and then the transport of the sheet is stopped. The image forming apparatus according to feature 2.

4. The system further includes a second sensor that detects whether or not the sheet is present at a second detection position which is upstream of the first sensor in the transport direction, The control unit, Based on the output of the second sensor, a sheet length acquisition process is performed to detect when the front end of the sheet has reached the second detection position and when the rear end of the sheet has reached the second detection position, and to acquire the sheet length in the transport direction of the sheet based on the detected front and rear ends of the sheet. A drive amount acquisition process is performed to acquire the drive amount based on the sheet length acquired by the sheet length acquisition process, In the aforementioned transport process, the first discharge roller and the second discharge roller are driven by the drive amount obtained in the drive amount acquisition process, and then the transport of the sheet is stopped. The image forming apparatus according to feature 2.

5. The control unit, In the sheet length acquisition process, based on the output of the second sensor, the sheet length in the conveying direction of the sheet is acquired based on the amount of the sheet conveyed from the detection of the front end of the sheet to the detection of the rear end of the sheet. The image forming apparatus according to feature 4.

6. The system further comprises a discharge motor for driving the first discharge roller and the second discharge roller, The control unit, During the transport process, if the first sensor does not detect the sheet even after a predetermined time has elapsed since the discharge motor was started, the discharge motor is stopped. The image forming apparatus according to feature 2.

7. The system further comprises a main motor that rotates either the heating rotating body or the pressurizing rotating body, The control unit, If, during the transport process, the first sensor does not detect the sheet even after a predetermined time has elapsed since the discharge motor was started, the main motor is also stopped. The image forming apparatus according to feature 6.

8. The main body of the device further includes a display panel, The control unit, If, during the transport process, the first sensor does not detect the sheet even after a predetermined time has elapsed since the discharge motor was started, a notification screen indicating that a jam has occurred will be displayed on the display panel. The image forming apparatus according to claim 6 or 7.

9. The system further comprises a discharge motor for driving the first discharge roller and the second discharge roller, The control unit, After the cutting process, the first discharge roller and the second discharge roller are driven to perform a discharge process in which the cut sheet is discharged to the outside of the main body of the device. During the discharge process, if the first sensor detects the sheet even after a predetermined time has elapsed since the discharge motor was started, the discharge motor is stopped. The image forming apparatus according to feature 2.

10. The main body of the aforementioned device is Display panel, It further possesses, The control unit, If, during the discharge process, the first sensor does not detect the sheet even after a predetermined time has elapsed since the discharge motor was started, a notification screen indicating that a jam has occurred will be displayed on the display panel. The image forming apparatus according to feature 9.

11. The aforementioned cutter is A blade for cutting the sheet, and a cutting motor for moving the blade in the cutting direction, It has, The control unit, In the cutting process, when the cutting motor is running and the discharge motor is not running, if the first sensor changes from detecting the sheet to not detecting it, the cutting motor is stopped. The image forming apparatus according to claim 9 or 10.

12. The first recall was, The system detects whether or not the sheet is present at the detection position between the cutter and the second discharge roller. The image forming apparatus according to feature 1.

13. A third discharge roller located in a discharge path branched from the transport path between the fuser and the first discharge roller, the third discharge roller being located at a position shorter than the length of the transport path from the fuser to the second discharge roller, and discharging the sheet to the outside of the main body of the device. Furthermore, The control unit, The device receives print data containing information indicating whether or not to cut the sheet, and if the information in the received print data indicates that the sheet will not be cut, the device transports the sheet using the third discharge roller and discharges the sheet from the device body to the outside without cutting it. The image forming apparatus according to feature 1.

14. A flapper that can be switched between a first position that guides the sheet toward the first discharge roller and a second position that guides the sheet toward the third discharge roller. Furthermore, The control unit, If the cutting status information indicates that cutting will occur, after the front end of the sheet has left the fuser but before it reaches the flapper, the flapper is switched to the first position. If the cutting status information indicates that cutting will not occur, the flapper is switched to the second position after the front end of the sheet has left the fuser but before it reaches the flapper. The image forming apparatus according to feature 13.

15. The length of the transport path from the fuser to the cutter is longer than half the length of the sheet to be cut in the transport direction. The image forming apparatus according to feature 1.

16. A discharge motor that drives the first discharge roller, A roller located between the first discharge roller and the fuser, A main motor that drives the roller and the fuser, Furthermore, The length of the transport path from the roller to the cutter is longer than half the length of the sheet to be cut in the transport direction. The control unit, The main motor remains running during the cutting process. The image forming apparatus according to feature 2.

17. An image forming unit located upstream of the fuser in the transport direction, which forms an image on the sheet, comprising: a photoreceptor drum; a developing roller that supplies toner to the photoreceptor drum; and a transfer roller that transfers the toner image formed on the photoreceptor drum to the sheet. The image forming apparatus according to claim 1, further comprising the features described above.

Images