Image forming apparatus

Abstract

The invention provides a technology capable of detecting a sheet at the periphery of a cutter with high precision. A printer (1) is characterized by being provided with: a device main body (2) having a conveyance path (201) for a sheet (S); a heating roller (61); a fixing device (6) that fixes the image formed on the sheet (S) to the sheet (S); a first discharge roller (85) that conveys the sheet (S) and is located downstream of the fuser (6); a second discharge roller (86) which is located downstream of the first discharge roller (85) in the conveyance direction and discharges the sheet (S) conveyed by the first discharge roller (85) to the outside of the device main body (2); a cutter (10) that is located at a cutter position (B) between the first discharge roller (85) and the second discharge roller (86) in the conveyance direction and is capable of cutting the sheet (S) in a cutting direction intersecting the conveyance direction; and a sheet detection sensor (SE4) that detects whether or not a sheet (S) is present at a first detection position between the first discharge roller (85) and the second discharge roller (86) in the conveyance direction.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus that cuts a sheet on which an image is formed by a cutter. Background Art

[0002] Patent Document 1 discloses 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 has a sheet detection unit that controls a branch guide according to the detection of the sheet by the sheet detection unit, and discharges the cut sheet to a first discharge tray and a second discharge tray, respectively.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2018-186448

[0006] Technical Problem to be Solved by the Invention

[0007] However, in the image forming apparatus described in Patent Document 1, high-precision detection of the sheet around the cutter is not considered. Summary of the Invention

[0008] An object of the present invention is to provide a technique capable of detecting a sheet with high precision around a cutter.

[0009] Technical Means for Solving the Technical Problem

[0010] To achieve the above object, an image forming apparatus according to the present invention is characterized by including: a device main body having a conveyance path for a sheet; a fixing device having a heating rotating body and a pressing rotating body, and fixing an image formed on the sheet to the sheet, with a nip formed between the pressing rotating body and the heating rotating body; a first discharge roller located downstream of the fixing device in the conveyance direction of the sheet along the conveyance path and conveying the sheet; a second discharge roller located downstream of the first discharge roller in the conveyance direction and discharging the sheet conveyed by the first discharge roller to the outside of the device main body; a cutter located at a cutter position and capable of cutting the sheet in a cutting direction crossing the conveyance direction, the cutter position being a position between the first discharge roller and the second discharge roller in the conveyance direction; and a first sensor that detects whether a sheet exists at a first detection position between the first discharge roller and the second discharge roller in the conveyance direction.

[0011] In the image forming apparatus according to the present invention, a cutter is disposed between a first discharge roller and a second discharge roller in the conveyance direction, and it is detected whether a sheet exists at a detection position between the same first discharge roller and second discharge roller, so that the sheet can be detected with high precision around the cutter.

[0012] Further, it is characterized in that it further includes a control unit that executes: a conveyance process of driving the first discharge roller and the second discharge roller based on the output of the first sensor by a driving amount required to convey the sheet from the front end of the sheet reaching the first detection position until the cutting position of the sheet reaches the cutter position, and then stopping the conveyance of the sheet; and a cutting process of cutting the sheet in the cutting direction using the cutter after the conveyance process.

[0013] In this way, based on the output of the first sensor located near the cutter position, the sheet is conveyed until the cutting position of the sheet reaches the cutter position, and the sheet is cut at this conveyance position, so that the sheet can be correctly cut at the cutting position of the sheet.

[0014] Further, it is characterized in that the control unit executes a driving amount acquisition process of receiving print data including the sheet size of the sheet and acquiring a driving amount based on the sheet size included in the received print data. In the conveyance process, after driving the first discharge roller and the second discharge roller by the driving amount acquired through the driving amount acquisition process, the control unit stops the conveyance of the sheet.

[0015] Thereby, it is possible to acquire the driving amount based on the simple information included in the received print job, that is, the sheet size, so that the process of acquiring the driving amount can be simplified.

[0016] Further, it is characterized in that it further includes a second sensor that detects whether a sheet exists at a second detection position upstream of the first sensor in the conveyance direction. The control unit executes: a sheet length acquisition process of detecting, based on the output of the second sensor, the situation where the front end of the sheet reaches the second detection position until the rear end of the sheet reaches the second detection position, and acquiring the sheet length in the conveyance direction of the sheet based on the detected front end and rear end of the sheet; and a driving amount acquisition process of acquiring a driving amount based on the sheet length acquired through the sheet length acquisition process. In the conveyance process, after driving the first discharge roller and the second discharge roller by the driving amount acquired through the driving amount acquisition process, the control unit stops the conveyance of the sheet.

[0017] Thereby, since the driving amount can be acquired based on the actually measured sheet length of the sheet, even if the sheet shrinks and the sheet length is shorter than the original sheet length, the sheet can be correctly cut at the expected cutting position.

[0018] Further, it is characterized in that, in the sheet length acquisition process, the control unit acquires the sheet length in the sheet conveyance direction based on the output of the second sensor and based on the conveyance amount of the sheet from when the front end of the sheet is detected until the rear end of the sheet is detected.

[0019] Thereby, it is possible to acquire the sheet length of the sheet based on the output of the second sensor already provided in the image forming apparatus, and thus it is possible to suppress the manufacturing cost of the entire image forming apparatus.

[0020] Further, it is characterized in that it further includes a discharge motor that drives the first discharge roller and the second discharge roller, and in the conveyance process, the control unit stops the drive of the discharge motor when the first sensor does not detect the sheet even after a predetermined time has elapsed since the start of the drive of the discharge motor.

[0021] Thereby, it is possible to accurately determine the occurrence of a sheet jam in the conveyance process and accurately perform error processing corresponding to the occurrence of the jam.

[0022] Further, it is characterized in that it further includes a main motor that drives either the heating rotating body or the pressing rotating body to rotate, and in the conveyance process, the control unit also stops the drive of the main motor when the first sensor does not detect the sheet even after a predetermined time has elapsed since the start of the drive of the discharge motor.

[0023] Thereby, it is possible to further accurately perform error processing corresponding to the occurrence of the jam.

[0024] Further, it is characterized in that the apparatus main body further has a display panel, and in the conveyance process, when the first sensor does not detect the sheet even after a predetermined time has elapsed since the start of the drive of the discharge motor, the control unit displays a notification screen notifying the occurrence of a jam on the display panel.

[0025] Thereby, it is possible to accurately notify the user of the occurrence of a sheet jam in the conveyance process.

[0026] Further, it is characterized in that it further includes a discharge motor that drives the first discharge roller and the second discharge roller, and after the cutting process, the control unit performs a discharge process, drives the first discharge roller and the second discharge roller, and discharges the cut sheet to the outside of the apparatus main body. In the discharge process, when the first sensor detects the sheet even after a predetermined time has elapsed since the start of the drive of the discharge motor, the control unit stops the drive of the discharge motor.

[0027] Thereby, it is possible to accurately determine the occurrence of a sheet jam in the discharge process after cutting and accurately perform error processing corresponding to the occurrence of the jam.

[0028] In addition, it is characterized in that the apparatus main body further has a display panel, and during the discharge process, when the first sensor does not detect the sheet even after a specified time has elapsed since the start of driving the discharge motor, the control unit causes a notification screen indicating a jam to be displayed on the display panel.

[0029] Thereby, it is possible to accurately notify the user of the occurrence of a jam of the sheet during the discharge process after cutting.

[0030] In addition, it is characterized in that the cutter has a blade for cutting the sheet and a cutting motor for moving the blade in the cutting direction. During the cutting process, when the cutting motor is driving and the discharge motor is not driving, if the state changes from the state where the first sensor detects the sheet to the state where the first sensor does not detect the sheet, the control unit stops the driving of the cutting motor.

[0031] Thereby, it is possible to accurately determine the situation where the sheet is detached during the cutting process and accurately perform corresponding error handling.

[0032] In addition, it is characterized in that the first sensor detects whether there is a sheet at the detection position between the cutter and the second discharge roller.

[0033] Thereby, it is possible to detect the sheet with high precision around the cutter.

[0034] In addition, it is characterized in that it further has a cover that opens and closes to cover the conveyance path between the first discharge roller and the second discharge roller. The first sensor outputs a first signal when the cover is in the open state and when the cover is in the closed state and the sheet is detected, and outputs a second signal when the cover is in the closed state and the sheet is not detected. When the sheet is not conveyed through the first discharge roller and the second discharge roller, if the first signal is output from the first sensor, the control unit determines that the cover is in the open state.

[0035] Thereby, it is possible to use one first sensor for both detecting the sheet and detecting the open state of the cover, and it is possible to reduce the manufacturing cost of the entire image forming apparatus.

[0036] In addition, it is characterized in that it further has a third discharge roller that is located on a discharge path branching from the conveyance path between the fuser and the first discharge roller and is located at a position shorter than the length of the conveyance path from the fuser to the second discharge roller, and discharges the sheet to the outside of the apparatus main body. The control unit receives print data including cutting presence / absence information indicating whether the sheet is cut. When the cutting presence / absence information included in the received print data indicates non-cutting, the sheet is conveyed by the third discharge roller and discharged from the apparatus main body to the outside without cutting the sheet.

[0037] Thus, without cutting the sheet, the sheet is discharged to the outside of the apparatus main body through a short path of the conveyance path, and thus the uncut sheet can be quickly discharged to the outside of the apparatus main body.

[0038] Further, it is characterized in that it further includes a shutter that can be switched to a first position for guiding the sheet toward the first discharge roller and a second position for guiding the sheet toward the third discharge roller. When the cut presence / absence information indicates cutting, before the leading end of the sheet detaches from the fixing unit and reaches the shutter, the control unit switches the shutter to the first position. When the cut presence / absence information indicates non-cutting, before the leading end of the sheet detaches from the fixing unit and reaches the shutter, the control unit switches the shutter to the second position.

[0039] Thus, based on the cut presence / absence information included in the printing job, the sheet is automatically guided to either the first discharge roller or the third discharge roller, which is convenient.

[0040] Further, it is characterized in that the length of the conveyance path from the fixing unit to the cutter is longer than half of the length of the sheet in the conveyance direction of the sheet that can be cut.

[0041] Thus, when cutting the sheet at the cutter position, the state of holding the sheet by the nip of the fixing unit is eliminated, and thus heat applied from the heating rotating body to the sheet can be suppressed in a state where the rotation of the pressurizing rotating body has stopped.

[0042] Further, it is characterized in that it further includes: a discharge motor that drives the first discharge roller; a roller that is located between the first discharge roller and the fixing unit; and a main motor that drives the roller and the fixing unit. The length of the conveyance path from the roller to the cutter is longer than half of the length of the sheet in the conveyance direction of the sheet that can be cut, and the control unit maintains the state of driving the main motor during the cutting process.

[0043] Thus, when cutting the sheet at the cutter position, the driving of the main motor for the roller or the fixing unit is not stopped, and only the discharge motor is stopped, so that the sheet can be stopped at the cutter position.

[0044] Further, it is characterized in that it further includes an image forming unit that is located upstream of the fixing unit in the conveyance direction, forms an image on the sheet, and the image forming unit includes a photosensitive drum, a developing roller that supplies toner to the photosensitive drum, and a transfer roller that transfers the toner image formed on the photosensitive drum to the sheet.

[0045] Thus, even in an electrophotographic image forming apparatus, the sheet can be detected with high accuracy around the cutter.

[0046] In addition, it is characterized by further comprising: a plurality of conveying rollers including a first discharge roller and a second discharge roller; a second sensor that detects whether a sheet is present at a second detection position between the first discharge roller and the fixing unit in the conveying direction; and a control unit that executes: a conveying process in which, during the conveying process of conveying a sheet along a conveying path using the plurality of conveying rollers, based on the detection results of the first sensor and the second sensor, the rotation amounts of the first discharge roller and the second discharge roller for causing the cutting position of an ideal sheet passing through a part of the conveying path to reach the cutter position are corrected, and after the first discharge roller and the second discharge roller are rotated by the corrected rotation amounts, the first discharge roller and the second discharge roller are stopped; and a cutting process in which, after the conveying process, the sheet is cut in the cutting direction using a cutter.

[0047] Accordingly, based on the detection results of the first sensor and the second sensor, the rotation amounts of the first discharge roller and the second discharge roller for causing the cutting position of an ideal sheet to reach the cutter position are corrected, the first discharge roller and the second discharge roller are stopped after being rotated by the corrected rotation amounts, and the sheet is cut at the stop position. Therefore, even if the sheet shrinks due to the heat applied to the sheet by the fixing unit, the sheet can be cut at a desired cutting position.

[0048] In addition, it is characterized in that, during the conveying process, the control unit obtains a first time when the leading end of the sheet reaches the first detection position based on the detection result of the first sensor, and obtains a second time when the trailing end of the sheet reaches the second detection position based on the detection result of the second sensor, and corrects the rotation amounts of the first discharge roller and the second discharge roller based on the obtained first time and second time.

[0049] Accordingly, since the length of the sheet is actually measured, even if the sheet shrinks due to the heat applied to the sheet by the fixing unit, the sheet can be cut at a desired cutting position.

[0050] In addition, the image forming apparatus of the present invention is characterized by further comprising: a main motor that drives either the heating rotating body or the pressing rotating body included in the fixing unit to rotate; and a discharge motor that drives the first discharge roller and the second discharge roller to rotate, and the control unit controls the main motor and the discharge motor such that the rotation speed of the discharge motor is faster than the rotation speed of the main motor.

[0051] Accordingly, even if the sheet passing through the fixing unit is deflected, since the conveying speed of the sheet is increased by the first discharge roller and the second discharge roller, the deflection of the sheet can be eliminated.

[0052] In addition, the image forming apparatus of the present invention is characterized in that it further includes a memory in which the rotation amounts of a first discharge roller and a second discharge roller required to convey a sheet from a second detection position of a second sensor to a first detection position of a first sensor are pre-stored as a first rotation amount. During a conveyance process, a control unit obtains the rotation amounts of the first discharge roller and the second discharge roller required from a first moment to a second moment as a second rotation amount, obtains the sheet length in the conveyance direction of the sheet after passing through a fixing device based on the first rotation amount and the second rotation amount, determines a cutting position on the sheet according to the obtained sheet length, and stops the rotational drive of a discharge motor.

[0053] Accordingly, it is not necessary to actually measure a fixed value, and thus the sheet length in the conveyance direction of the sheet can be obtained more accurately.

[0054] In addition, it is characterized in that the control unit performs the following control: after obtaining the second moment, the discharge motor is driven to rotate until the determined cutting position on the sheet reaches a cutter position.

[0055] Accordingly, the conveyance of the sheet can be stopped when the determined cutting position on the sheet reaches the cutter position.

[0056] In addition, it is characterized in that the discharge motor is a stepping motor, and the control unit controls the stop timing of the discharge motor by the number of steps of the stepping motor.

[0057] Accordingly, the stop timing of the discharge motor can be controlled by a simple method of counting the number of steps of the stepping motor.

[0058] In addition, it is characterized in that the first sensor is located on the upstream side in the conveyance direction compared to the cutter position, the first rotation amount is represented by the number of steps of the stepping motor, the rotation amounts of the first discharge roller and the second discharge roller required to convey a sheet from the first detection position of the first sensor to the cutter position are pre-stored in the memory as a third rotation amount, the third rotation amount is represented by the number of steps of the stepping motor, during the conveyance process, the control unit obtains the second rotation amount by the number of steps of the stepping motor, and after obtaining the second moment,

[0059] performs the following control: drives the discharge motor to rotate by {first rotation amount - (first rotation amount + second rotation amount) / 2 + third rotation amount}.

[0060] Accordingly, even if the sheet shrinks due to the heat applied to the sheet by the fixing device, it is possible to accurately cut at the center in the conveyance direction of the sheet by a simple method of counting the number of steps of the stepping motor.

[0061] In addition, it is characterized in that the first sensor is located on the downstream side in the conveying direction with respect to the cutter position, the first rotation amount is expressed in terms of the number of steps of the stepping motor, and the rotation amounts of the first discharge roller and the second discharge roller required to convey the sheet from the cutter position to the first detection position of the first sensor are pre-stored in the memory as the third rotation amount, and the third rotation amount is expressed in terms of the number of steps of the stepping motor. During the conveying process, the control unit obtains the second rotation amount in terms of the number of steps of the stepping motor. After obtaining the second moment,

[0062] perform the following control: drive the discharge motor to rotate {the first rotation amount - (the first rotation amount + the second rotation amount) / 2 - the third rotation amount}.

[0063] Thereby, even if the sheet shrinks due to the heat applied to the sheet by the fixing device, it is possible to correctly cut at the center in the conveying direction of the sheet by a simple method of counting the number of steps of the stepping motor.

[0064] In addition, it is characterized in that the apparatus main body has: a first discharge path, which is a part of the conveying path and is used to discharge the sheet to the outside of the apparatus main body via the cutter position; a second discharge path, which is a part of the conveying path and is a path different from the first discharge path and is used to discharge the sheet to the outside of the apparatus main body; and a shutter that guides the sheet to either the first discharge path or the second discharge path. The control unit receives a printing job including information related to whether it is necessary to cut the sheet using the cutter. When it is determined based on the printing job that sheet cutting is required, the control unit moves the position of the shutter so as to guide the sheet to the first discharge path. When it is determined based on the printing job that sheet cutting is not required, the control unit moves the position of the shutter so as to guide the sheet to the second discharge path.

[0065] Thereby, when sheet cutting is required, the sheet is guided to the first discharge path by the shutter, and when sheet cutting is not required, the sheet is guided to the second discharge path by the shutter, which is convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1 is a cross-sectional view showing a schematic structure of a monochrome laser printer according to a first embodiment of the present invention.

[0067] Figure 2 shows Figure 1 a perspective view showing a schematic structure of a cutter included in the monochrome laser printer.

[0068] Figure 3 shows Figure 1 a block diagram showing a control structure of the monochrome laser printer.

[0069] Figure 4 It is a diagram showing the cutting position ((a)) of the sheet and the sheet cut at this cutting position.

[0070] Figure 5 It is a diagram showing the operation of the sheet detection sensor in the open state of the cover ((a)), the closed state of the cover and the non-detection state of the sheet ((b)), and the closed state of the cover and the detection state of the sheet ((c)).

[0071] Figure 6 It is showing Figure 1 The flowchart of the steps of the printing process in the monochrome laser printer of

[0072] Figure 7 It is showing Figure 6 The flowchart of the detailed steps of the sheet printing and cutting process included in the printing process of

[0073] Figure 8 It is showing Figure 7 The flowchart of the detailed steps of the sheet conveyance step determination process based on the set sheet length included in the sheet printing and cutting process of

[0074] Figure 9 It is showing Figure 7 The flowchart of the detailed steps of the sheet conveyance process to the cutter position included in the sheet printing and cutting process of

[0075] Figure 10 It is showing Figure 7 The flowchart of the detailed steps of the sheet cutting process included in the sheet printing and cutting process of

[0076] Figure 11 It is showing Figure 10 The flowchart of the detailed steps of the error stop process for sheet detachment detection included in the sheet cutting process of

[0077] Figure 12 It is Figure 7 The flowchart of the detailed steps of the error stop process for JAM included in the sheet printing and cutting process of

[0078] Figure 13 It is showing Figure 1 The flowchart of the steps of the cover state determination process in the monochrome laser printer of

[0079] Figure 14 It is the flowchart of the detailed steps of the sheet printing and cutting process in the monochrome laser printer according to the second embodiment of the present invention.

[0080] Figure 15 It is showing Figure 14Flowchart of the detailed steps of the sheet conveyance step determination process based on measuring the sheet length included in the sheet printing and cutting process.

[0081] Figure 16 It is used to illustrate Figure 15 The figure of the sheet conveyance step determination process based on measuring the sheet length.

[0082] Figure 17 It is a cross-sectional view showing the schematic structure of the monochrome laser printer according to the third embodiment of the present invention.

[0083] Figure 18 It is a figure used to illustrate the problems generated when cutting a shrunk sheet and the countermeasures therefor.

[0084] Figure 19 It represents Figure 6 Flowchart of the detailed steps of the sheet printing and cutting process included in the printing process.

[0085] Figure 20 It represents Figure 6 Flowchart of the detailed steps of the sheet conveyance process to the cutter position included in the printing process.

[0086] Figure 21 It represents Figure 6 Flowchart of the detailed steps of the sheet cutting process included in the printing process.

[0087] Figure 22 It is used to illustrate Figure 20 The figure of the sheet conveyance process to the cutter position.

[0088] Figure 23 It is used to illustrate Figure 20 The sheet conveyance process to the cutter position of Figure 22 The continuation figure.

[0089] Figure 24 It is a cross-sectional view showing the schematic structure of the monochrome laser printer according to the fourth embodiment of the present invention.

[0090] Figure 25 It represents Figure 24 Flowchart of the steps of the sheet conveyance process to the cutter position in the monochrome laser printer.

[0091] Figure 26 It is used to illustrate Figure 25 The figure of the sheet conveyance process to the cutter position. Detailed implementation manners

[0092] Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

[0093] (First Embodiment)

[0094] Figure 1 FIG. 1 is a cross-sectional view showing a schematic structure of a monochrome laser printer 1 according to a first embodiment of the present invention. The monochrome laser printer 1 is an example of an image forming apparatus. Hereinafter, the monochrome laser printer 1 will be simply referred to as the printer 1. The printer 1 includes a device main body 2, a conveying unit 3, an image forming unit 4, a fixing unit 6, a cutter 10, and an operation panel PA. Hereinafter, for convenience of explanation, as shown by the arrows in FIG. 1, the up-down direction and the front-back direction of the printer 1 are defined. In addition, the near front side of the paper surface is defined as the left, and the opposite side of the paper surface is defined as the right. Figure 1 As shown by the arrows in FIG. 1, the up-down direction and the front-back direction of the printer 1 are defined. In addition, the near front side of the paper surface is defined as the left, and the opposite side of the paper surface is defined as the right.

[0095] The device main body 2 has a front cover 21, a supply tray 31, a discharge tray 22, a conveying path 201, and a re-conveying path 202. The front cover 21 is attached to the front surface of the device main body 2 in a state where it can be opened and closed. The supply tray 31 is attached to the lower part of the device main body 2 in a state where it can be loaded and unloaded. A sheet S is placed on the supply tray 31. The sheet S is a standardized sheet such as A4 size. The sheet S is, for example, a paper medium such as plain paper or thick paper, but is not limited thereto, and may also be an OHP film. The discharge tray 22 is provided at the upper part of the device main body 2, and the sheet S on which an image has been formed is placed on the discharge tray 22.

[0096] The conveying path 201 is a path for conveying the sheet S placed on the supply tray 31 toward the discharge tray 22 in the conveying direction via the image forming unit 4. The conveying path 201 branches from a first branch position D1 into a first discharge path 201A and a second discharge path 201B. Therefore, the sheet S conveyed through the image forming unit 4 includes the sheet discharged to the discharge tray 22 via the first discharge path 201A and the sheet discharged to the discharge tray 22 via the second discharge path 201B.

[0097] The re-conveying path 202 is a path for reversing the sheet S on which an image has been formed on one side and conveying it again toward the image forming unit 4. The re-conveying path 202 branches from the conveying path 201 at a second branch position D2 and merges with the conveying path 201 at a merging position J on the upstream side in the conveying direction of the pre-alignment sensor SE1.

[0098] The conveying 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 stopper 88, re-conveying rollers 38 and 39, a main motor 108 (see Figure 3 ) and a discharge motor 109 (see Figure 3)。The plurality of conveying rollers include a pickup roller 33, a separating roller 34, a registration roller 35, a roller 36, a first discharge roller 85, a second discharge roller 86, and a third discharge roller 87. The printer 1 uses these plurality of conveying rollers to convey the sheet S along the conveying path 201.

[0099] The pickup roller 33 picks up the sheet S in the supply tray 31 lifted upward by the sheet pressing plate 32 and conveys it toward the conveying path 201. The separating roller 34 separates the sheets S picked up by the pickup roller 33 one by one.

[0100] The registration roller 35 is disposed upstream of the image forming unit 4 in the conveying path 201. After aligning the direction of the front end of the sheet S, the registration roller 35 conveys the sheet S toward the image forming unit 4. The conveying direction of the registration roller 35 for conveying the sheet is a direction from the front to the rear. The roller 36 conveys the sheet S that has passed through the fixing unit 6 toward the first discharge roller 85 or the third discharge roller 87. The conveying direction of the fixing unit 6 and the roller 36 for conveying the sheet is a direction from the front to the rear and obliquely upward.

[0101] The first discharge roller 85 and the second discharge roller 86 are disposed in the first discharge path 201A. The first discharge roller 85 and the second discharge roller 86 are a pair of rollers composed of a driving roller and a driven roller. Further, the first discharge roller 85 is disposed at a position upstream of the cutter position B where the cutter 10 is disposed, and the second discharge roller 86 is disposed at a position downstream of the cutter position B.

[0102] The first discharge roller 85 and the second discharge roller 86 discharge the sheet S to the discharge tray 22 by forward rotation. The forward rotation is a rotation for conveying the sheet S in the conveying direction, which is equivalent to a counterclockwise rotation about the left - right direction of the apparatus main body 2. The conveying direction of the first discharge roller 85 for conveying the sheet is a direction from the rear to the front and upward. In addition, the conveying direction of the second discharge roller 86 for conveying the sheet S is a direction from the rear to the front.

[0103] On the other hand, the third discharge roller 87 is disposed in the second discharge path 201B. The third discharge roller 87 is also a pair of rollers composed of a driving roller and a driven roller. The third discharge roller 87 discharges the sheet S to the discharge tray 22 by forward rotation. In addition, the third discharge roller 87 conveys the sheet S to the re - conveying path 202 by rotation in a direction opposite to the forward rotation, that is, reverse rotation. The reverse rotation is a rotation for conveying the sheet S in a direction opposite to the conveying direction, which is equivalent to a clockwise rotation about the left - right direction of the apparatus main body 2. That is, the conveying direction of the sheet S conveyed by the forward rotation of the third discharge roller 87 is a direction from the rear to the front, and the direction of the sheet S conveyed by the reverse rotation of the third discharge roller 87 is a direction from the front to the rear.

[0104] The refeeding path 202 is provided with refeeding rollers 38 and 39. The refeeding rollers 38 and 39 feed the sheet S conveyed to the refeeding path 202 toward the image forming unit 4. Through the refeeding rollers 38 and 39, the sheet S on which an image has been formed on one side is re-fed toward the image forming unit 4 via the refeeding path 202, so that image formation can be performed on both sides of the sheet S. That is, the conveying direction of the sheet S by the refeeding rollers 38 and 39 is from the rear to the front.

[0105] The image forming unit 4 forms an image on the sheet S and is housed in the apparatus main body 2. The image forming unit 4 includes a drum cartridge 5 and a laser unit 7. The drum cartridge 5 has a photosensitive drum 51, a toner storage section 57, a supply roller 56, a developing roller 55, a charger 52, a transfer roller 53, and a pinch roller 54. By opening the front cover 21, the drum cartridge 5 can be detached from the apparatus main body 2. The pinch roller 54 of the drum cartridge 5 faces the registration roller 35. The pinch roller 54 rotates following the rotation of the registration roller 35 and feeds the sheet S together with the registration roller 35.

[0106] The photosensitive drum 51 rotates in the clockwise direction using the driving force transmitted from the main motor 108 (refer to Figure 3 ) and feeds the sheet S in the conveying direction. In the photosensitive drum 51, the rotation for feeding the sheet S in the conveying direction, i.e., the forward rotation, is in the clockwise direction. The toner storage section 57 stores toner. The supply roller 56 supplies the toner in the toner storage section 57 to the developing roller 55. The charger 52 is a vacuum tube type charger that uniformly charges the surface of the photosensitive drum 51. In addition, the charger 52 can also be a charging roller.

[0107] A transfer roller 53 is disposed at a position facing the photosensitive drum 51. The transfer roller 53 forms a transfer nip TN between the transfer roller 53 and the photosensitive drum 51 in the conveying path 201. In addition, a transfer belt can be used instead of the transfer roller 53.

[0108] The apparatus main body 2 has a laser unit 7 in the upper part of its interior. The laser unit 7 includes a polygon mirror 131 (refer to Figure 3 ), a laser emitting section 132 (refer to Figure 3 ), lenses and mirrors (not shown), etc. The laser unit 7 exposes the surface of the photosensitive drum 51 by scanning the surface of the photosensitive drum 51 at high speed with a laser (refer to the double-dot dash line of Figure 1 ) based on the image data emitted from the laser emitting section 132.

[0109] The surface of the photosensitive drum 51 is exposed by the laser unit 7, thereby forming an electrostatic latent image based on the image data. The developing roller 55 forms a toner image on the surface of the photosensitive drum 51 by supplying toner to the electrostatic latent image formed on the surface of the photosensitive drum 51.

[0110] A transfer voltage is applied to the transfer roller 53 by a voltage application unit (not shown). The transfer roller 53 transfers the toner image formed on the surface of the photosensitive drum 51 to the sheet S passing through the transfer nip TN by conveying the sheet S between the transfer roller 53 and the photosensitive drum 51. In this way, image formation on the sheet S is performed.

[0111] A fixing device 6 is disposed on the downstream side of the image forming unit 4 in the conveyance path 201. The fixing device 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 applying rotating body and forms a nip N between the heating roller 61 and the pressure roller 62 to apply pressure to the sheet S. The pressure roller 62 rotates counterclockwise by the driving force of the main motor 108. In the pressure roller 62, the rotation for conveying the sheet S in the conveying direction, that is, the forward rotation, is counterclockwise. In this way, the pressure roller 62 is a driving roller and the heating roller 61 is a driven roller. On the contrary, the heating roller 61 can also be a driving roller that rotates clockwise by the driving force of the main motor 108, and the pressure roller 62 can be a driven roller.

[0112] The heater 63 is, for example, a halogen heater and heats the heating roller 61. The temperature sensor 64 is disposed 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 ).

[0113] The fixing device 6 heats the sheet S by the heating roller 61 and rotates the pressure roller 62, so that the sheet S is conveyed while being pressed between the heating roller 61 and the pressure roller 62, thereby fixing the image formed on the sheet S by the image forming unit 4 to the sheet S.

[0114] In addition, the fixing device 6 has a structure including the heating roller 61, the pressure roller 62, and the heater 63, but is not limited thereto. For example, the fixing device 6 may also have a structure including a heater, a holding plate that receives radiant heat from the heater, a heating belt that rotates around the holding plate, and a pressure roller. Additionally, the fixing device 6 may also have a structure including a substrate on which a heat generating pattern is formed, a belt that rotates around the substrate, and a pressure roller, and the substrate and the belt are in contact. Further, the fixing device 6 may also have a structure including a heating roller, a heater, and a pressure belt.

[0115] In the first discharge path 201A, a cutter 10 is disposed at a cutter position B between a first discharge roller 85 and a 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 the cutter position B. In a state where the rotation of the first discharge roller 85 and the second discharge roller 86 is stopped, the printer 1 uses the cutter 10 to cut the sheet S at the cutter position B.

[0116] Figure 2 shows a schematic structure of the cutter 10. As Figure 2 shown, the cutter 10 includes a cutter frame 11, a slide rail 12, a fixed blade 13, a sheet passing portion 14, a moving 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 track formed on the cutter frame 11 and extending in the axial direction. The fixed blade 13 is a flat blade fixed to the cutter frame 11 and extending in the axial direction. The sheet passing portion 14 is a space formed in the cutter frame 11 for the sheet S to pass through. In the present embodiment, the sheet passing portion 14 is formed between the slide rail 12 and the fixed blade 13. The moving blade 15 is a disc-shaped blade and is rotatably fixed to the slide holder 16. The cutting motor 106 is, for example, a DC motor with an encoder, and the encoder (not shown) outputs a signal related to the rotation of the DC motor to the CPU 101.

[0117] 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 rotates forward, the slide holder 16 slides from one side in the axial direction to the other side, and when the cutting motor 106 rotates backward, the slide holder 16 slides from the other side in the axial direction to one side. The slide holder 16 can move from Figure 2 the initial position shown by the solid line to the cutting completion position shown by the dotted line. When the sheet S is at the cutter position B, if the slide holder 16 moves along the slide rail 12 to the cutting completion position, one sheet S is clamped by the fixed blade 13 and the moving blade 15 and cut into two sheets. After the sheet S is cut, the printer 1 discharges the cut sheet S cut into two sheets to the discharge tray 22 by rotating the first discharge roller 85 and the second discharge roller 86 for a predetermined time.

[0118] In addition, the printer 1 is configured to be able to cut A4 and letter-sized sheets S at the center of the sheet in the conveying direction by the cutter 10. That is, Figure 1The length of the conveyance path 201 from the nip N to the cutter position B is designed to be longer than half (148.5 mm) of the dimension (297 mm) in the conveyance direction of the A4-sized sheet S. With this configuration, when cutting the A4-sized 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 fixing device 6. When 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 being held by the nip N of the fixing device 6, it is necessary to stop the rotation of the pressure roller 62. However, when the rotation of the pressure roller 62 is stopped while the sheet S is being held by the nip N of the fixing device 6, heat is locally applied to the same portion of the sheet S from the heating roller 61. Therefore, when cutting the sheet S at the cutter position B with the rotation of the first discharge roller 85 and the second discharge roller 86 stopped, it is necessary for the rear end of the sheet S to pass through the nip N of the fixing device 6.

[0119] Furthermore, Figure 1 the length of the conveyance path 201 from the nip of the roller 36 to the cutter position B is designed to be longer than half (148.5 mm) of the dimension (297 mm) in the conveyance direction of the A4-sized sheet S. With this configuration, when cutting the 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 of the roller 36. When cutting the sheet S at the cutter position B with the rotation of the first discharge roller 85 and the second discharge roller 86 stopped, if the sheet is held and rotated by the nips of the roller 36 and the pressure roller 62, there is a concern that the sheet S may be bent into a corrugated shape between the first discharge roller 85 and the roller 36. Therefore, by adopting the above configuration, without stopping the rotation of the roller 36 and the fixing device 6, and only stopping the rotation of the first discharge roller 85 and the second discharge roller 86, the sheet can be stopped at the cutting position without being bent into a corrugated shape.

[0120] In addition, the length of the second discharge path 201B is designed to be shorter than the length of the first discharge path 201A. That is, the second discharge roller 86 is located on the front side compared to the third discharge roller 87. This is to quickly discharge the sheet S to the outside of the apparatus main body 2 when not cutting the sheet S after image formation.

[0121] Next, with reference to Figure 3 the control structure of the printer 1 will be described. As Figure 3 shown, the printer 1 further includes an ASIC 105, a ROM 102, a RAM 103, an NVRAM 104, an alignment post sensor SE2, a discharge sensor SE3, a sheet detection sensor SE4, and a communication interface (I / F) 130.

[0122] The ASIC 105 is equipped with a CPU 101. The CPU 101 is an example of a control unit and performs overall control of each part of the printer 1. The ASIC 105 is electrically connected to a ROM 102, a RAM 103, an NVRAM 104, a cutting motor 106, a shutter 88, an electromagnetic clutch 107, a main motor 108, a discharge motor 109, a pre-alignment sensor SE1, an after-alignment sensor SE2, a discharge sensor SE3, a sheet detection sensor SE4, an operation panel PA, a communication I / F 130, a drum cartridge 5, a fuser 6, and a laser unit 7.

[0123] Various control programs, various settings, etc. for controlling the printer 1 are stored in the ROM 102. In addition, the printing process described later is included in the control program. Figure 6 The printing process described later is included in the control program.

[0124] The RAM 103 is used as a work area for reading various control programs and a storage area for temporarily storing image data included in a job. The CPU 101 controls each part of the printer 1 while storing the processing results in the RAM 103 or the NVRAM 104 according to the control program read from the ROM 102 and the signals output from various sensors.

[0125] The CPU 101 drives the cutting motor 106 to move the sliding carriage 16, so that the moving blade 15 moves in the width direction of the sheet S to cut the sheet S.

[0126] The main motor 108 transmits driving force to a pickup roller 33, a registration roller 35, a roller 36, a re-feed roller 38, 39, a pressure roller 62, and a drum cartridge 5. When the CPU 101 drives the main motor 108 to rotate forward, the driving force is transmitted to the roller 36, the pressure roller 62, the photosensitive drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35. Then, the roller 36, the pressure roller 62, the photosensitive drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35 rotate in the direction of conveying the sheet S along the conveying direction.

[0127] Specifically, the roller 36 and the pressure roller 62 rotate counterclockwise. The photosensitive drum 51 rotates clockwise. The developing roller 55 rotates counterclockwise. The pickup roller 33 rotates counterclockwise. The registration roller 35 rotates counterclockwise.

[0128] On the other hand, the structure is as follows: Even if the CPU 101 drives the main motor 108 to rotate reversely, the driving force is not transmitted to the roller 36, the pressure roller 62, the drum cartridge 5, the pickup roller 33, and the registration roller 35.

[0129] In addition, the CPU 101 drives the main motor 108 to rotate forward, transmits the driving force to the re-feed rollers 38 and 39, and causes them to rotate in the clockwise direction. On the other hand, the CPU 101 drives the main motor 108 to rotate in reverse, transmits the driving force to the re-feed rollers 38 and 39, and causes the re-feed rollers 38 and 39 to rotate in the clockwise direction.

[0130] The discharge motor 109 is, for example, a stepping motor, and transmits the 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 to rotate forward, the first discharge roller 85, the second discharge roller 86, and the third discharge roller 87 rotate in the counterclockwise direction. Thereby, 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, when the CPU 101 drives the discharge motor 109 to rotate in reverse, the first discharge roller 85, the second discharge roller 86, and the third discharge roller 87 rotate in the clockwise direction. Thereby, the sheet S being conveyed in the second discharge path 201B is conveyed in the direction opposite to the conveying direction.

[0131] The CPU 101 controls the electromagnetic clutch 107. When the CPU 101 turns on the electromagnetic clutch 107, the driving force of the main motor 108 is transmitted to the pickup roller 33. On the other hand, when the CPU 101 turns off the electromagnetic clutch 107, the driving force of the main motor 108 is not transmitted to the pickup roller 33.

[0132] The CPU 101 controls the shutter 88. For example, by turning on / off a shutter solenoid (not shown), the CPU 101 can switch the position of the shutter 88 to the first position ( Figure 1 the position 88A shown by the dashed line in Figure 1 ) and the second position (the position 88B shown by the solid line in

[0133] ). The shutter 88 located at the first position 88A guides the sheet S conveyed by the roller 36 to the first discharge path 201A. The shutter 88 located at the second position 88B guides the sheet S conveyed by the roller 36 to the second discharge path 201B. In addition, the shutter 88 located at the second position 88B guides the sheet S located in the second discharge path 201B to the re-feed path 202. The pre-alignment sensor SE1 is a sensor that is disposed upstream of the registration roller 35 in the conveying path 201 and detects the passage of the sheet S. The pre-alignment sensor SE1 has an actuator that swings by contacting the sheet S and a photoelectric sensor that detects the position of the actuator. The pre-alignment sensor SE1 outputs an on-signal in the state where the sheet S is passing through, and outputs an off-signal in the state where the sheet S is not passing through. The detection signal of the pre-alignment sensor SE1 is output to the CPU 101.

[0134] After alignment, the sensor SE2 is disposed upstream of the fixing unit 6 in the conveyance path 201. Specifically, it is disposed between the registration roller 35 and the transfer roller 53, and is a sensor that detects the passage of the sheet S. The post-alignment sensor SE2 has the same structure as the pre-alignment sensor SE1. The detection signal of the post-alignment sensor SE2 is output to the CPU 101.

[0135] The discharge sensor SE3 is disposed between the fixing unit 6 and the roller 36 in the conveyance path 201, and detects the passage of the sheet S. The discharge sensor SE3 has the same structure as the pre-alignment sensor SE1. The detection signal of the discharge sensor SE3 is output to the CPU 101.

[0136] The sheet detection sensor SE4 is disposed between the cutter position B and the second discharge roller 86, detects the passage of the sheet S, and detects 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 in the open state and when the cover 23 is in the closed state and the sheet S is passing through, and outputs an OFF signal when the cover 23 is in the closed state and the sheet S is not passing through.

[0137] Figure 5 Indicates the operation of the sheet detection sensor SE4, Figure 5 In (a), it indicates when the cover 23 is in the open state, Figure 5 In (b), it indicates when the cover 23 is in the closed state and the sheet S is not passing through, Figure 5 In (c), it indicates when the cover 23 is in the closed state and the sheet S is passing through. As Figure 5 shown, the sheet detection sensor SE4 is an actuator type photoelectric sensor, and has an actuator 120 and a transmissive photoelectric sensor 121. The transmissive photoelectric sensor 121 has a light emitting portion 121A and a light receiving portion (not shown), and outputs an OFF signal (an example of a second signal) when the optical path irradiated from the light emitting portion 121A to the light receiving portion is blocked by the actuator 120, and outputs an ON signal (an example of a first signal) when the optical path is not blocked.

[0138] 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 form a V shape when viewed from the side, that is, when viewed from the left-right direction, and can rotate clockwise and counterclockwise about a rotation axis in the left-right direction (not shown). In Figure 5When the cover 23 shown in (a) is in the open state, the first arm 120A of the actuator 120 is separated from the cover 23. Therefore, the actuator 120 rotates counterclockwise to the maximum extent by the action of a spring or the like, for example. At this time, since the optical path of the transmissive photoelectric sensor 121 is not blocked by the actuator 120, the sheet detection sensor SE4 outputs an ON signal. In addition, when Figure 5 the cover 23 shown in (b) is in the closed state and the sheet S has not passed through, since the cover 23 abuts against the upper end of the first arm 120A of the actuator 120, the actuator 120 rotates clockwise as compared with when the cover 23 is in the open state. At this time, the optical path of the transmissive photoelectric sensor 121 is blocked by the second arm 120B of the actuator 120, so the sheet detection sensor SE4 outputs an OFF signal. In addition, when Figure 5 the cover 23 shown in (c) is in the closed state and the sheet S is passing through, the first arm 120A of the actuator 120 abuts against the sheet S, so the actuator 120 rotates further clockwise. At this time, the optical path of the transmissive photoelectric sensor 121 is not blocked by the second arm 120B of the actuator 120, so the sheet detection sensor SE4 outputs an ON signal. The sheet detection sensor is, for example, a photosensor that emits light toward the conveyance path without an actuator and receives the reflected light, or a photosensor that emits different signals by detecting a change in the amount of received light when there is a sheet on the conveyance path and when there is no sheet, thereby determining whether the sheet is located at that position.

[0139] Return to Figure 3 , the operation panel PA is arranged on the upper surface of the apparatus main body 2. The operation panel PA has, for example, a touch panel in which a touchpad and a display are integrally formed and a button section. The operation panel PA receives the operation of the user and outputs the received information to the CPU 101. The user can, for example, set whether to cut the sheet S by operating the operation panel PA.

[0140] The communication I / F 130 is connected to a network such as a LAN and can be connected to an external device such as a PC equipped with a driver for the printer 1. The CPU 101 can receive a printing job via the communication I / F 130. The printing job includes image data for image formation, the size and type of the sheet S for image formation, various information required for forming an image on the sheet S, and information on whether to cut the sheet S.

[0141] Hereinafter, with reference to Figures 6 to 13 the control processing executed by the printer 1 configured as described above will be described in detail.

[0142] Figure 6Represents the steps of the printing process executed by the ASIC 105, particularly the CPU 101. This printing process is executed when the printer 1 can receive a printing job or a printing command, such as when the power of the printer 1 is turned on or when the printer 1 is in the standby state, etc. Thereafter, in the description of each process, the step is denoted as "S".

[0143] In Figure 6 , first, the CPU 101 stands by until a printing job is received via the communication I / F 130 or a printing command is received via the operation panel PA (both S10 and S12: No). If a printing job or a printing command is received (either S10 or S12: Yes), the CPU 101 proceeds to S14 with the processing.

[0144] In S14, the CPU 101 determines whether the sheet S to be printed needs to be cut. In the present embodiment, this determination is made based on whether the information of the sheet S included in the printing job or the printing command indicates cutting. That is, if the user sets a mode specifying the cutting of the sheet S during the setting of the printing job, or sets a mode specifying the cutting of the sheet S during the setting of the printing command via the operation panel PA, then the printing job or the printing command includes the information of cutting the sheet S. In this determination, if the cutting of the sheet S is required (S14: Yes), the CPU 101 proceeds to S16 with the processing. On the other hand, if the cutting of the sheet S is not required (S14: No), the CPU 101 proceeds to S20 with the processing.

[0145] In S16, the CPU 101 moves the shutter 88 to the first position 88A. As described above, the first position 88A is the position for guiding the sheet S conveyed by the roller 36 to the first discharge path 201A. Then, after the CPU 101 executes the sheet printing and cutting process (S18), the printing process ends.

[0146] On the other hand, in S20, the CPU 101 moves the shutter 88 to the second position 88B. As described above, the second position 88B is the position for guiding the sheet S conveyed by the roller 36 to the second discharge path 201B. Then, after the CPU 101 performs the normal printing (S22), the printing process ends. In the present embodiment, the normal printing means that after printing an image on the sheet S based on the printing job or the printing command, the sheet S is discharged to the discharge tray 22 without being cut.

[0147] Figure 7 Represents the detailed steps of the sheet printing and cutting process of S18. In Figure 7 , first, the CPU 101 executes the process of determining the number of sheet conveyance steps based on the set sheet length (S30). Figure 8 Represents the detailed steps of the process of determining the number of sheet conveyance steps based on the set sheet length.

[0148] In Figure 8 this case, the CPU 101 acquires the sheet size information included in the printing job or the printing command (S70). Specifically, the sheet size information refers to information such as "A4 size" and "letter size". Further, after the CPU 101 acquires the number of steps of the discharge motor required for the "cut position of the sheet at the time point when the sheet detection sensor changes from off to on" corresponding to the acquired sheet size information to reach the "cutter position" (S72), the process of determining the number of sheet conveyance steps based on the set sheet length ends. More specifically, in the ROM 102 or the NVRAM 104 or the like, for each sheet size, the number of steps of the discharge motor required for the "cut position of the sheet at the time point when the sheet detection sensor changes from off to on" to reach the "cutter position" is stored. For example, if the sheet size information is A4, the CPU 101 acquires the corresponding number of steps for A4 stored in the ROM 102 or the NVRAM 104.

[0149] In Figure 4 the (a) of

[0150] Returning to Figure 7 this case, the CPU 101 drives the main motor 108 to rotate forward (S32). At this time, the CPU 101 also turns on the heater 63.

[0151] Next, the CPU 101 executes a pickup command (S34). Thereby, the CPU 101 turns on the electromagnetic clutch 107. When the electromagnetic clutch 107 is turned on, as described above, since the driving force of the main motor 108 is transmitted to the pickup roller 33, the sheet S in the supply tray 31 is picked up and conveyed toward the conveyance path 201.

[0152] Next, the CPU 101 stands by until the post-alignment sensor SE2 switches from OFF to ON (S36: No). As described above, the post-alignment sensor SE2 is disposed in the conveyance path 201 between the registration roller 35 and the transfer roller 53, and outputs an ON signal in a state where the sheet S is passing therethrough, and outputs an OFF signal in a state where the sheet S is not passing therethrough. Therefore, in S36, the CPU 101 stands by until the post-alignment sensor SE2 detects the leading edge of the sheet S. Then, when the post-alignment sensor SE2 detects the leading edge of the sheet S (S36: Yes), the CPU 101 starts image formation on the sheet S (S38). In addition, image formation may also start on the occasion other than the post-alignment sensor SE2 detecting the leading edge of the sheet S. It is sufficient to perform image formation in such a manner that the toner image formed by the photosensitive drum 51 is correctly transferred to the image formation position of the sheet S.

[0153] Next, the CPU 101 stands by until the discharge sensor SE3 switches from OFF to ON (S40: No). As described above, the discharge sensor SE3 is disposed in the conveyance path 201 between the fixing unit 6 and the roller 36, and outputs an ON signal in a state where the sheet S is passing therethrough, and outputs an OFF signal in a state where the sheet S is not passing therethrough. Therefore, in S40, the CPU 101 stands by until the discharge sensor SE3 detects the leading edge of the sheet S. Then, when the discharge sensor SE3 detects the leading edge of the sheet S (S40: Yes), the CPU 101 drives the discharge motor 109 to rotate forward (S42). Thereby, the first discharge roller to the third discharge roller 85 to 87 start rotating.

[0154] 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 disposed in the conveyance path 201 between the cutter position B and the second discharge roller 86, outputs an on signal when the sheet S is passing therethrough, and outputs an off signal when the sheet S is not passing therethrough. Further, the sheet detection sensor SE4 outputs an on signal even when the cover 23 is in the open state as described above, but this case is not considered here. Therefore, in S44, the CPU 101 determines whether the sheet detection sensor SE4 has detected the leading edge of the sheet S. Then, when the sheet detection sensor SE4 has not detected the leading edge of the sheet S (S44: No), the CPU 101 determines whether a predetermined time has elapsed (S46). If the predetermined time has not elapsed (S46: No), the CPU 101 returns the process to S44. On the other hand, if the predetermined time has elapsed (S46: Yes), the CPU 101 executes an error stop process based on JAM (jam) (S48) and then ends the sheet printing and cutting process. Here, the "predetermined time" is a time with a margin of the predetermined time with respect to the normal time required from when the discharge motor 109 starts rotating forward until the sheet detection sensor SE4 detects the leading edge of the sheet S. That is, even if this time elapses and the sheet detection sensor SE4 has not detected the leading edge of the sheet S, it is possible to determine that the sheet S is in a jam state on the conveyance path 201.

[0155] Figure 12 Shows the detailed steps of the error stop process based on JAM. In Figure 12 , the CPU 101 stops the discharge motor 109 (S120), stops the main motor 108 (S122), and further stops other devices (S124). Examples of other devices include the image forming unit 4 and the fixing unit 6. Then, after the CPU 101 displays a notification screen (not shown) notifying that a jam has occurred on the operation panel PA (S126), the error stop process based on JAM ends. Further, in the notification screen, in addition to displaying the occurrence of a jam, it is preferable to display information indicating where the jam has occurred.

[0156] Return to Figure 7 , in the determination of S44, when the sheet detection sensor SE4 has detected the leading edge of the sheet S (S44: Yes), the CPU 101 executes a sheet conveyance process to the cutter position (S50). Figure 9 Shows the detailed steps of the sheet conveyance process to the cutter position.

[0157] In Figure 9Among them, the CPU 101 starts measuring the number of steps of the discharge motor 109 (S80). Since the discharge motor 109 is a stepping motor as described above, the CPU 101 can simply measure the number of steps of the discharge motor 109 by counting the pulses input to the motor driver (not shown) of the discharge motor 109. The measurement of the number of steps can be performed, for example, by incrementing the number of steps measurement area (not shown) ensured in the RAM 103.

[0158] Next, the CPU 101 stands by until the number of steps obtained in S72 ( Figure 8 ) is counted (S82: No). When the counting of the number of steps is completed (S82: Yes), the CPU 101 stops the discharge motor 109 (S84). Thus, the sheet S stops in a state where its cutting position CP has reached the cutter position B. In addition, the CPU 101 may be configured to use the number of steps obtained in S72 as an initial value, decrement for each pulse input to the motor driver of the discharge motor 109, and stop the discharge motor 109 when the remaining number of steps is zero.

[0159] Return to Figure 7 , the CPU 101 executes the sheet cutting process (S52). Figure 10 Shows the detailed steps of the sheet cutting process. In Figure 10 Among them, the CPU 101 drives the cutting motor 106 to rotate forward (S90). Thus, the moving blade 15 moves in the direction of contacting the sheet S, and the cutting of the sheet S starts. Next, the CPU 101 determines whether the moving blade 15 has reached the cutting completion position (S92). That is, it determines whether the cutting of the sheet S is completed. As the cutting motor 106, for example, in the case of a DC motor with an encoder, a signal representing the rotation direction, rotation position, and rotation speed corresponding to the rotation of the cutting motor 106 is output from the encoder. Therefore, the CPU 101 can determine whether the moving blade 15 has reached the cutting completion position based on this signal. In the determination of S92, when the moving blade 15 has not reached the cutting completion position (S92: No), the CPU 101 determines whether the sheet detection sensor SE4 has switched from on to off (S100). In this determination, when the sheet detection sensor SE4 remains on (S100: No), the CPU 101 returns the process to S92. On the other hand, when the sheet detection sensor SE4 switches from on to off (S100: Yes), the CPU 101 determines that the sheet S being cut has been detached from the first discharge path 201A, and after executing the error stop process based on the sheet detachment detection (S102), ends the sheet cutting process.

[0160] Figure 11 Shows the detailed steps of the error stop process based on the sheet detachment detection. InFigure 11 Among them, the CPU 101 executes the same processing as that in S120 to S124 in S110 to S114, that is, the processing of stopping the discharge motor 109, the main motor 108, and other devices. Then, after the CPU 101 displays a notification screen (not shown) notifying the detachment of the sheet on the operation panel PA (S126), it ends the error stop processing based on the sheet detachment detection.

[0161] Return to Figure 10 In the determination of S92, when the moving blade 15 reaches the cutting completion position (S92: Yes), the CPU 101 stops the cutting motor 106 (S94) and then drives it to reverse (S96). Thus, the moving blade 15 moves from Figure 2 the cutting completion position shown by the dotted line to the initial position shown by the solid line. Then, the CPU 101 determines whether the moving blade 15 has reached the initial position (S98). If it has not reached the initial position (S98: No), the same processing as that in S100 and S102 is performed in S104 and S106. That is, during the return of the moving blade 15 to the initial position, the CPU 101 determines whether the sheet S has been detached from the first discharge path 201A. If it has been detached (S104: Yes), it executes the error stop processing based on the sheet detachment detection.

[0162] On the other hand, in the determination of S98, when the moving blade 15 has reached the initial position (S98: Yes), the CPU 101 ends the sheet cutting process.

[0163] Return to Figure 7 Here, the CPU 101 drives the discharge motor 109 to rotate forward (S54). Thus, the sheet S cut at the cutting position CP starts to be conveyed toward the discharge tray 22. Next, the CPU 101 determines whether the sheet detection sensor SE4 has switched from on to off (S56). That is, it determines whether the discharge of the sheet S to the discharge tray 22 is completed. And when the sheet detection sensor SE4 has not switched from on to off even after a specified time (S58: Yes), that is, when the sheet S stays on the first discharge path 201A, the CPU 101 determines that the sheet S is in the JAM state. After executing the same JAM-based error stop processing as that in S48 (S60), it ends the sheet printing and cutting process.

[0164] On the other hand, in the determination of S56, when the sheet detection sensor SE4 switches from ON to OFF (S56: YES), after a predetermined time has elapsed, the discharge motor 109 is stopped (S62). As a result, the bisected sheet S is discharged to the discharge tray 22. Therefore, the "predetermined time" is the time from when the sheet on the upstream side in the conveyance direction in the bisected sheet S is discharged from the first discharge path 201A until it reaches the discharge tray 22.

[0165] Next, the CPU 101 determines whether there is printing of the next sheet in the job being executed (S64). In this determination, when there is printing of the next sheet (S64: YES), the CPU 101 returns the process to S34 and continues the processes after S34. On the other hand, when there is no printing of the next sheet (S64: NO), the CPU 101 stops the main motor 108 (S66) and then ends the sheet printing and cutting process.

[0166] Next, the cover open state detection process will be described. As described above, the sheet detection sensor SE4 outputs an ON signal when the cover 23 is in the open state, when the cover 23 is in the closed state and the sheet S is passing through, and outputs an OFF signal when the cover 23 is in the closed state and the sheet S is not passing through. The cover open state detection process is a process of detecting the open state of the cover 23 based on the output result of the sheet detection sensor SE4.

[0167] Figure 13 Steps showing the cover open state detection process executed by the CPU 101. The cover open state detection process runs in parallel with the printing process ( Figure 6 ) and starts, for example, when the power of the printer 1 is turned on or when the printer 1 is in the standby state.

[0168] In Figure 13 , in a state where there is no sheet S being processed in the first discharge path 201A, the CPU 101 determines whether the sheet detection sensor SE4 switches from OFF to ON (S130, S132). In this determination, when the sheet detection sensor SE4 switches from OFF to ON in a state where there is no sheet 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), displays a notification screen (not shown) notifying that the cover 23 is in the open state on the operation panel PA (S136), and then ends the cover open state detection process.

[0169] Since the sheet detection sensor SE4 outputs an ON signal when the cover 23 is in the open state and when the cover 23 is in the closed state and the sheet S is passing through, in order to determine that the cover 23 is in the open state, it is necessary to exclude the state when the cover 23 is in the closed state and the sheet S is passing through. That is, 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 due to the passage of the sheet S. Therefore, it is determined that the sheet detection sensor SE4 is not turned on due to the passage of the sheet S. Then, in S132, it is determined that the sheet detection sensor SE4 is not turned on due to the passage of the sheet S, but is turned on because the cover 23 has become in the open state.

[0170] As described above, the printer 1 of the present embodiment is characterized by including: a device main body 2 having a conveyance path 201 for the sheet S; a fixing device 6 having a heating roller 61 and a pressure roller 62 that forms a nip N with the heating roller 61 and fixes the image formed on the sheet S to the sheet S; a first discharge roller 85 that is located downstream of the fixing device 6 in the conveyance direction of the sheet S along the conveyance path 201 and conveys the sheet S; a second discharge roller 86 that is located downstream of the first discharge roller 85 in the conveyance direction and discharges the sheet S conveyed by the first discharge roller 85 to the outside of the device main body 2; a cutter 10 that is located at the cutter position B and can cut the sheet S in a cutting direction intersecting the conveyance direction, and the cutter position B is a position between the first discharge roller 85 and the second discharge roller 86 in the conveyance direction; and a sheet detection sensor SE4 that detects whether there is a sheet S at a first detection position between the first discharge roller 85 and the second discharge roller 86 in the conveyance direction.

[0171] Thus, in the printer 1 of the present embodiment, the cutter 10 is disposed between the first discharge roller 85 and the second discharge roller 86 in the conveyance direction, and it is detected whether the sheet S exists at the detection position between the same first discharge roller 85 and the second discharge roller 86. Therefore, the sheet S can be detected with high precision around the cutter 10.

[0172] Incidentally, in the present embodiment, the heating roller 61 is an example of a "heating rotating body". The pressure roller 62 is an example of a "pressing rotating body". The sheet detection sensor SE4 is an example of a "first sensor".

[0173] In addition, the printer 1 also includes a CPU 101. Moreover, it is characterized in that the CPU 101 executes: a conveyance process, based on the output of the sheet detection sensor SE4, driving the first discharge roller 85 and the second discharge roller 86 by the number of steps required to convey the sheet S from the front end of the sheet S reaching the first detection position to the cutting position of the sheet S reaching the cutter position B, and then stopping the conveyance of the sheet S; and a cutting process, after the conveyance 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 "driving amount".

[0174] In this way, based on the output of the sheet detection sensor SE4 located near the cutter position B, the sheet S is conveyed until the cutting position CP of the sheet S reaches the cutter position B, and the sheet S is cut at this conveyance position, so that the sheet S can be correctly cut at the cutting position CP of the sheet S.

[0175] Moreover, it is characterized in that the CPU 101 executes a driving amount acquisition process, receives a printing job including the sheet size of the sheet S, and acquires the number of steps based on the sheet size included in the received printing job. In the conveyance process, after driving the first discharge roller 85 and the second discharge roller 86 by the number of steps acquired through the number of steps acquisition process, the conveyance of the sheet S is stopped.

[0176] Thereby, the number of steps of the discharge motor 109 can be acquired based on the simple information, i.e., the sheet size, included in the received printing job, so that the process of acquiring the number of steps can be simplified.

[0177] In addition, the printer 1 also includes a discharge motor that drives the first discharge roller 85 and the second discharge roller 86. Moreover, it is characterized in that the CPU 101 stops the driving of the discharge motor 109 in the conveyance process when the sheet detection sensor SE4 does not detect the sheet S even after a predetermined time has elapsed since the start of the driving of the discharge motor 109.

[0178] Thereby, the occurrence of a jam of the sheet S during the conveyance process can be accurately determined, and error processing corresponding to the occurrence of the jam can be accurately performed.

[0179] In addition, the printer 1 also includes a main motor 108 that drives either the heating roller 61 or the pressure roller 62 to rotate. Moreover, it is characterized in that the CPU 101 also stops the driving of the main motor 108 in the conveyance process when the sheet detection sensor SE4 does not detect the sheet S even after a predetermined time has elapsed since the start of the driving of the discharge motor 109.

[0180] Thereby, error processing corresponding to the occurrence of a jam can be further accurately performed.

[0181] Specifically, the device main body 2 also has a display panel. During the conveyance process, when the sheet S is not detected by the sheet detection sensor SE4 even after a specified time has elapsed since the start of driving the discharge motor 109, the CPU 101 displays a notification screen notifying of a jam on the operation panel PA.

[0182] Thereby, it is possible to accurately notify the user of the occurrence of a jam of the sheet S during the conveyance process.

[0183] In addition, the printer 1 further includes a discharge motor 109 that drives the first discharge roller 85 and the second discharge roller 86. Specifically, after the cutting process, the CPU 101 executes a discharge process, drives the first discharge roller 85 and the second discharge roller 86, and discharges the cut sheet S to the outside of the device main body 2. During the discharge process, when the sheet S is detected by the sheet detection sensor SE4 even after a specified time has elapsed since the start of driving the discharge motor 109, the driving of the discharge motor 109 is stopped.

[0184] Thereby, it is possible to accurately determine the occurrence of a jam of the sheet S during the discharge process after cutting, and accurately perform error processing corresponding to the occurrence of the jam.

[0185] In addition, specifically, the device main body 2 also has an operation panel PA. During the discharge process, when the sheet S is not detected by the sheet detection sensor SE4 even after a specified time has elapsed since the start of driving the discharge motor 109, the CPU 101 causes a notification screen notifying of a jam to be displayed on the operation panel PA. Incidentally, the operation panel PA is an example of a "display panel".

[0186] Thereby, it is possible to accurately notify the user of the occurrence of a jam of the sheet S during the discharge process after cutting.

[0187] In addition, specifically, the cutter 10 has a moving blade 15 for cutting the sheet S and a cutting motor 106 for moving the moving blade 15 in the cutting direction. During the cutting process, when the cutting motor 106 is driving and the discharge motor 109 is not driving, and the state changes from the sheet S being detected by the sheet detection sensor SE4 to not being detected, the CPU 101 stops the driving of the cutting motor 106. Incidentally, the moving blade 15 is an example of a "blade".

[0188] Thereby, it is possible to accurately determine the situation where the sheet S is detached during the cutting process, and accurately perform error processing corresponding thereto.

[0189] In addition, specifically, the sheet detection sensor SE4 detects whether the sheet S exists at the detection position between the cutter 10 and the second discharge roller 86.

[0190] Thus, it is possible to detect the sheet S with high precision around the cutter 10.

[0191] In addition, the printer 1 further includes a cover 23 that opens and closes to cover the conveyance path 201 between the first discharge roller 85 and the second discharge roller 86. And, it is characterized in that the sheet detection sensor SE4 outputs an ON signal when the cover 23 is in the open state and when the cover 23 is in the closed state and the sheet S is detected, outputs an OFF signal when the cover 23 is in the closed state and the sheet S is not detected, and when the sheet S is not conveyed through the first discharge roller 85 and the second discharge roller 86, when an ON signal is output from the sheet detection sensor SE4, the CPU 101 determines that the cover 23 is in the open state. The ON signal is an example of the "first signal". The OFF signal is an example of the "second signal".

[0192] Thus, it is possible to use one sheet detection sensor SE4 for both the detection of the sheet S and the detection of the open state of the cover 23, and it is possible to reduce the manufacturing cost of the entire printer 1.

[0193] In addition, the printer 1 further includes a third discharge roller 87 that is located on a second discharge path 201B that branches from the conveyance path 201 between the fixing unit 6 and the first discharge roller 85, and is located at a position shorter than the length of the conveyance path 201 from the fixing unit 6 to the second discharge roller 86, and discharges the sheet S to the outside of the apparatus main body 2. And, it is characterized in that the CPU 101 receives a print job including cutting presence / absence information indicating whether the sheet S is cut or not, and when the cutting presence / absence information included in the received print job indicates not to cut, conveys the sheet S through the third discharge roller 87 and discharges the sheet S from the apparatus main body 2 to the outside without cutting the sheet S. Incidentally, the print job is an example of the "print data". The second discharge path 201B is an example of the "discharge path".

[0194] Thus, when the sheet S is not cut, the sheet S is discharged to the outside of the apparatus main body 2 through a short path of the conveyance path 201, so that the uncut sheet S can be quickly discharged to the outside of the apparatus main body 2.

[0195] In addition, the printer 1 further includes a stopper 88 that can be switched to 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. And, it is characterized in that when the cutting presence / absence information indicates cutting, the CPU 101 switches the stopper 88 to the first position 88A after the leading end of the sheet S has separated from the fixing unit 6 and before reaching the stopper 88, and when the cutting presence / absence information indicates not to cut, the CPU 101 switches the stopper 88 to the second position 88B after the leading end of the sheet S has separated from the fixing unit 6 and before reaching the stopper 88.

[0196] Accordingly, based on the information on whether there is cutting included in the printing job, the sheet S is automatically guided to either the first discharge roller 85 or the third discharge roller 87, which is convenient.

[0197] In addition, it is characterized in that the length of the conveying path 201 from the fixing device 6 to the cutter 10 is longer than half of the length of the sheet in the conveying direction of the sheet that can be cut.

[0198] Accordingly, when cutting the sheet S at the cutter position B, the state of clamping the sheet S by the nip N of the fixing device 6 is eliminated. Therefore, it is possible to suppress the application of heat from the heating roller 61 to the sheet S in a state where the rotation of the pressure roller 62 has stopped. In addition, the length in the present embodiment is the length in the conveying direction from the downstream end in the conveying direction of the nip N of the fixing device 6 to the fixed blade 13 of the cutter 10. However, for example, it may also be the length in the conveying direction from the downstream end in the conveying direction of the outer circumference of the pressure roller 62 or the heating roller 61 of the fixing device 6 to the fixed blade 13 of the cutter 10.

[0199] In addition, the printer 1 is characterized by further comprising: a discharge motor 109 that drives the first discharge roller 85; a roller 36 that is located between the first discharge roller 85 and the fixing device 6; and a main motor 108 that drives the roller 36 and the fixing device 6. The length of the conveying path 201 from the roller 36 to the cutter 10 is longer than half of the length of the sheet S in the conveying direction of the sheet that can be cut, and the CPU 101 maintains the state of driving the main motor 108 during the cutting process.

[0200] Accordingly, when cutting the sheet S at the cutter position B, the driving of the main motor 108 for the roller 36 or the fixing device 6 is not stopped, but only the discharge motor 109 is stopped, so that the sheet S can be stopped at the cutter position B.

[0201] (Second Embodiment)

[0202] Next, a second embodiment of the present invention will be described. Since this embodiment is configured by changing a part of the sheet printing and cutting process (refer to Figure 7 ) described in the first embodiment, the description will be centered on the changed part, and the description of other parts will be appropriately omitted. In addition, the hardware of this embodiment is used as is Figures 1 to 3 the hardware described therein.

[0203] Figure 14 The steps of the sheet printing and cutting process executed by the ASIC 105, particularly the CPU 101, of the printer 1 representing this embodiment. In Figure 7In the sheet printing and cutting process, the process is determined (S30) by the number of sheet conveyance steps based on the set sheet length, and the number of steps of the discharge motor 109 that makes the cutting position CP of the sheet S reach the cutter position B is determined. In this regard, in Figure 14 the sheet printing and cutting process, it is different in that the process is determined (S146) by the number of sheet conveyance steps based on the measured sheet length, and the number of steps of the discharge motor 109 that makes the cutting position CP of the sheet S reach the cutter position B is determined. Therefore, in Figure 14 in, the same symbols are used for the same processes as Figure 7 above, and the description thereof is appropriately omitted.

[0204] When the post-alignment sensor SE2 detects the front end of the sheet S (S36: Yes), the CPU 101 starts measuring the sheet length of the sheet S (S140). Since the measurement of the sheet length is performed by measuring time, the CPU 101 can, for example, perform an up-count on a timer area (not shown) secured in the RAM 103 at every prescribed time (for example, every 0.01 second). In this case, in S140, the CPU 101 starts the up-count of the timer area.

[0205] Next, after the CPU 101 executes the processes of S38 to S42, it stands by until the post-alignment sensor SE2 detects the rear end of the sheet S (S142: No). Then, when the post-alignment sensor SE2 detects the rear end of the sheet S (S142: Yes), the CPU 101 ends the measurement of the sheet length of the sheet S (S144). That is, the CPU 101 ends the up-count of the timer area.

[0206] Next, the CPU 101 executes the sheet conveyance step determination process (S146) based on the measured sheet length. Figure 15 shows the detailed steps of the sheet conveyance step determination process based on the measured sheet length. In Figure 15 this, the CPU 101 acquires the measured sheet length information (S150). In the present embodiment, since the measured sheet length information is the count value of the timer area, the CPU 101 reads and acquires the count value from the timer area.

[0207] Next, after the CPU 101 calculates the number of steps of the discharge motor required for the "cutting position of the sheet at the time point when the sheet detection sensor changes from off to on" to reach the "cutter position" based on the acquired measured sheet length information (S152), it ends the sheet conveyance step determination process based on the measured sheet length.

[0208] Figure 16 is a diagram for explaining the sheet cutting position determination process based on the Figure 15 measured sheet length. As shown in Figure 16As shown, the CPU 101 calculates the sheet length L of the sheet S in terms of the number of steps of the discharge motor 109 by the following formula (1).

[0209] L(STEP) = T(s) × V(mm / s) / D(mm / STEP) ……(1)

[0210] Where, T: the time elapsed from when the front end of the sheet S is detected by the post - alignment sensor SE2 until the rear end of the sheet S is detected = the count value in the timer area × the time per count;

[0211] V: the conveyance speed at which the main motor 108 conveys the sheet S;

[0212] D: the conveyance distance per step of the discharge motor 109.

[0213] And, if the cutting position CP of the sheet S is at the center of the sheet length, the number of steps from the sheet detection sensor SE4 to the cutting position CP is L / 2. Further, since the cutter position B is 20 STEP upstream from the detection position of the sheet detection sensor SE4, the number of steps calculated in S152 becomes = L / 2 - 20(STEP).

[0214] Therefore, when the CPU 101 executes the sheet conveyance process to the cutter position ( Figure 14 S50), the sheet S stops in a state where the cutting position CP reaches the cutter position B.

[0215] As described above, the printer 1 of the present embodiment further includes a post - alignment sensor SE2 that detects whether the sheet S exists at a second detection position on the upstream side in the conveyance direction from the sheet detection sensor SE4. Then, it is characterized in that the CPU 101 executes: a sheet length acquisition process that detects the situation from when the front end of the sheet S reaches the second detection position until the rear end of the sheet S reaches based on the output of the post - alignment sensor SE2, and acquires the sheet length in the conveyance direction of the sheet S according to the detected front end and rear end of the sheet S; and a drive amount acquisition process that acquires the number of steps based on the sheet length acquired by the sheet length acquisition process, and in the conveyance process, after driving the first discharge roller 85 and the second discharge roller 86 by the number of steps acquired by the number - of - steps acquisition process, stops the conveyance of the sheet S. Incidentally, the post - alignment sensor SE2 is an example of the "second sensor".

[0216] Thus, since the number of steps can be acquired based on the actually measured sheet length of the sheet S, even if the sheet S shrinks and the sheet length is shorter than the original sheet length, the sheet S can be correctly cut at the expected cutting position.

[0217] Further, it is characterized in that, in the sheet length acquisition process, the CPU 101 acquires the sheet length in the sheet conveyance direction of the sheet S based on the output of the post-alignment sensor SE2 and based on the conveyance amount of the sheet S from the detection of the front end of the sheet S to the detection of the rear end of the sheet S.

[0218] Thus, it is possible to acquire the sheet length of the sheet S based on the output of the post-alignment sensor SE2 already provided in the printer 1, and thus it is possible to suppress the manufacturing cost of the entire printer 1.

[0219] (Third Embodiment)

[0220] Next, a third embodiment of the present invention will be described. Refer to Figure 6 and Figures 17 to 21 to detail the control process executed by the printer 1 of this embodiment. This embodiment is configured by changing the installation position of the sheet detection sensor SE4 described in the first embodiment. The hardware of this embodiment is generally used as Figures 1 to 3 the described hardware, but in order to clarify the installation position of the sheet detection sensor SE4 in this embodiment, a Figure 17 cross-sectional view is used instead of Figure 1 . However, in Figure 17 , the same reference numerals are assigned to the same components as Figure 1 .

[0221] In this embodiment, the sheet detection sensor SE4 is disposed between the first discharge roller 85 and the cutter position B and is a sensor that detects the passage of the sheet S. The sheet detection sensor SE4 has the same structure as the pre-alignment sensor SE1. The detection signal of the sheet detection sensor SE4 is output to the CPU 101.

[0222] Figure 18 It is a diagram for explaining the problem points generated when cutting the sheet Sa formed by shrinking the sheet S and the countermeasures therefor. Figure 18 (a) of Figure 18 shows the sheet S before shrinkage, and the dashed line in the figure indicates the cutting position CP for cutting the sheet S at the center in the long side direction, i.e., the conveyance direction. In contrast, Figure 18 (b) of Figure 18As shown in (c) of, the sheet Sa can be cut into two sheets of length La / 2. Hereinafter, the control process for correctly cutting the shrunk sheet Sa in half will be described.

[0223] Figure 19 Indicates Figure 6 The detailed steps of the sheet printing and cutting process of S18 in this embodiment. In Figure 19 First, the CPU 101 drives the main motor 108 to rotate forward (S200). At this time, the CPU 101 also turns on the heater 63.

[0224] Next, the CPU 101 executes a pick-up command (S202). As a result, the CPU 101 turns on the electromagnetic clutch 107. When the electromagnetic clutch 107 is turned on, as described above, since the driving force of the main motor 108 is transmitted to the pick-up roller 33, the sheet S in the supply tray 31 is picked up and conveyed toward the conveyance path 201.

[0225] Next, the CPU 101 waits until the post-alignment sensor SE2 switches from off to on (S204: No). As described above, the post-alignment sensor SE2 is disposed between the registration roller 35 and the transfer roller 53 in the conveyance path 201, outputs an on signal in a state where the sheet S is passing through, and outputs an off signal in a state where the sheet S is not passing through. Therefore, in S204, the CPU 101 waits until the post-alignment sensor SE2 detects the leading end of the sheet S. Then, when the post-alignment sensor SE2 detects the leading end of the sheet S (S204: Yes), the CPU 101 starts image formation on the sheet S by the image forming unit 4 (S206).

[0226] Next, the CPU 101 stands by until the discharge sensor SE3 switches from off to on (S208: No). As described above, the discharge sensor SE3 is disposed in the conveyance path 201 between the fixing unit 6 and the roller 36, outputs an on signal in a state where the sheet S is passing therethrough, and outputs an off signal in a state where the sheet S is not passing therethrough. Therefore, in S208, the CPU 101 stands by until the discharge sensor SE3 detects the leading edge of the sheet S. Then, when the discharge sensor SE3 detects the leading edge of the sheet S (S208: Yes), the CPU 101 drives the discharge motor 109 to rotate forward (S210). Thereby, the first to third discharge rollers 85 to 87 start rotating. In addition, the CPU 101 controls the discharge motor 109 and the main motor 108 such that the rotation speed of the discharge motor 109 is faster than the rotation speed of the main motor 108. This is to eliminate the deflection of the sheet S when the sheet S is conveyed in a deflected state between the roller 36 and the first discharge roller 85 or the third discharge roller 87. That is, if the conveyance speeds of the first discharge roller 85 and the third discharge roller 87 are faster than the conveyance speed of the roller 36, then when the sheet S is conveyed by the first discharge roller 85 or the third discharge roller 87, the conveyance speed of the portion of the sheet S that has separated from the roller 36 becomes faster, and thus the deflected state gradually tends to be eliminated.

[0227] Next, the CPU 101 stands by until the sheet detection sensor SE4 switches from off to on (S212: No). As described above, the sheet detection sensor SE4 is disposed in the conveyance path 201 between the first discharge roller 85 and the cutter position B, outputs an on signal in a state where the sheet S is passing therethrough, and outputs an off signal in a state where the sheet S is not passing therethrough. Therefore, in S210, the CPU 101 stands by until the sheet detection sensor SE4 detects the leading edge of the sheet S. Then, when the sheet detection sensor SE4 detects the leading edge of the sheet S (S210: Yes), the CPU 101 starts measuring the number of steps of the discharge motor 109 (S214). Since the discharge motor 109 is a stepping motor as described above, the CPU 101 can measure, that is, count, the number of steps when operating the discharge motor 109. In addition, the measurement result (count value) can be stored, for example, in a step number counting area (not shown) secured in a predetermined area of the RAM 103. Figure 22 Fig. (a) shows a state where the leading edge of the sheet Sa reaches the detection position of the sheet detection sensor SE4.

[0228] Next, the CPU 101 stands by until the discharge sensor SE3 switches from ON to OFF (S216: No). That is, in S216, the CPU 101 stands by until the discharge sensor SE3 detects the rear end of the sheet S. Then, when the discharge sensor SE3 detects the rear end of the sheet S (S216: Yes), the CPU 101 executes the sheet conveyance process to the cutter position (S218). Figure 22 (b) of Figure 22 shows a state where the rear end of the sheet Sa reaches the detection position of the discharge sensor SE3.

[0229] Figure 20 Shows the detailed steps of the sheet conveyance process to the cutter position in S218. In Figure 20 , first, the CPU 101 determines the actually measured number of STEPs (S230). The actually measured number of STEPs (an example of the second rotation amount) is the number of STEPs from when the sheet detection sensor SE4 detects the front end of the sheet Sa until the discharge sensor SE3 detects the rear end of the sheet Sa. The determination of the actually measured number of STEPs can be performed by reading the count value stored in the number-of-STEP count area at this time.

[0230] Next, the CPU 101 calculates the number of STEPs of the sheet length of the sheet S by adding a predetermined value (length X: expressed in the number of STEPs) and the actually measured number of STEPs (S232). Then, the CPU 101 calculates the number of STEPs from the cutting position CP of the sheet S to the cutter position B in the conveyance path 201 including the first discharge path 201A by the following formula (2) (S234).

[0231] Number of STEPs of sheet length / 2 - Actually measured number of STEPs + Number of STEPs from the sheet detection sensor SE4 to the cutter position B... (2)

[0232] Figure 23(a) is a diagram for explaining the processing of S232 and S234, showing the state where the rear end of the sheet Sa reaches the detection position of the discharge sensor SE3. At this time, the measured STEP number determined in S230 is 140 STEP. And since the length X from the discharge sensor SE3 to the sheet detection sensor SE4 is a fixed established value, i.e., 200 STEP, the STEP number of the sheet length in the conveying direction of the sheet Sa can be calculated as 200 + 140 = 340 STEP. The fixed established value of 200 STEP for the length X (an example of the first rotation amount) is pre-stored in the NVRAM104. The CPU101 only needs to read the 200 STEP of the length X from the NVRAM104 for use. In this way, when the STEP number of the sheet length is calculated, its cutting position CPa is calculated as the sheet length STEP number / 2. Specifically, the cutting position CPa = 170 STEP. And since the length X = 200 STEP, the cutting position CPa is located 30 STEP (= 200 - 170) upstream from the detection position of the sheet detection sensor SE4. Furthermore, the length Y from the detection position of the sheet detection sensor SE4 to the cutter position B is a fixed established value, i.e., 40 STEP. The fixed established value of 40 STEP for the length Y (an example of the third rotation amount) is pre-stored in the NVRAM104. Therefore, if the cutting position CPa conveys the sheet Sa 70 STEP (= 30 + 40) downstream from the current position where the discharge sensor SE3 is in the off state, the cutting position CPa reaches the cutter position B. That is, Equation (2) represents the STEP number from when the rear end of the sheet S reaches the detection position of the discharge sensor SE3 until the cutting position CP of the sheet S reaches the cutter position B.

[0233] Return to Figure 20 , and then the CPU101 stands by until the discharge motor 109 is driven to rotate by the amount of the STEP number calculated in S234 (S236: No). When the discharge motor 109 is driven to rotate by this amount of the STEP number (S236: Yes), the CPU101 ends the sheet conveying process to the cutter position. Subsequently, the CPU101 makes the process enter Figure 6 S220 of

[0234] In S220, the CPU101 stops the discharge motor 109. Then, the CPU101 executes the sheet cutting process (S222).

[0235] Figure 21 Shows the detailed steps of the sheet cutting process. In Figure 21 , first, the CPU101 drives the cutting motor 106 to rotate forward (S240). By the forward rotation drive of the cutting motor 106, the moving blade 15 moves from the initial position toward the cutting completion position ( Figure 2starting from the position indicated by the dashed line in the figure). Then, the CPU 101 stands by until the moving blade 15 of the cutter 10 reaches the cutting completion position ( Figure 2 the position indicated by the dashed line in the figure) (S242: No). When the moving blade 15 reaches the cutting completion position (S242: Yes), the CPU 101 proceeds to S244. In addition, the CPU 101 counts the rotational speed of the cutting motor 106 based on the output signal from the encoder provided along with the cutting motor 106, and determines the situation where the moving blade 15 reaches the cutting completion position from the initial position ( Figure 2 the position indicated by the solid line in the figure) based on this count value.

[0236] In S244, the CPU 101 stops the cutting motor 106. Subsequently, the CPU 101 drives the cutting motor 106 to reverse (S246). Then, the CPU 101 stands by until the moving blade 15 reaches the initial position (S248: No). When the moving blade 15 reaches the initial position (S248: Yes), the CPU 101 ends the sheet cutting process. Subsequently, the CPU 101 proceeds to Figure 19 S224.

[0237] When the CPU 101 executes the sheet cutting process, the sheet S stops in a state where its cutting position CP reaches the cutter position B. Therefore, if the sheet cutting process is executed while the sheet S is stopped in this state, as shown in Figure 23 (b) of the figure, even if the sheet S shrinks to become the sheet Sa, the sheet Sa is cut into two sheets at the center in the conveying direction (cutting position CPa).

[0238] In Figure 19 S224, the CPU 101 drives the discharge motor 109 to rotate forward, and after a specified time, stops the discharge motor 109. As a result, the bisected sheet S is discharged to the discharge tray 22. Therefore, the "specified time" is the time it takes for the sheet on the upstream side in the conveying direction of the bisected sheet S to be discharged from the first discharge path 201A to the discharge tray 22.

[0239] Next, the CPU 101 determines whether there is printing of the next sheet in the job being executed (S226). In this determination, if there is printing of the next sheet (S226: Yes), the CPU 101 returns the process to S202 and continues the processing after S202. On the other hand, if there is no printing of the next sheet (S226: No), the CPU 101 stops the main motor 108 (S228) and then ends the sheet printing and cutting process.

[0240] As described above, the printer 1 of the present embodiment includes: a device main body 2 having a conveyance path 201 for a sheet S; a fixing device 6 having a heating roller 61 and a pressure roller 62 that forms a nip N with the heating roller 61, and fixing an image formed on the sheet S to the sheet S; conveyance rollers 35, 36, 85 to 87 having a first discharge roller 85 and a second discharge roller 86, the first discharge roller 85 being located downstream of the fixing device 6 in the conveyance direction of the sheet S along the conveyance path 201 and conveying the sheet S, the second discharge roller 86 being located downstream of the first discharge roller 85 in the conveyance direction and discharging the sheet S conveyed by the first discharge roller 85 to the outside of the device main body 2; a cutter 10 located at a cutter position B and capable of cutting the sheet S in a cutting direction intersecting the conveyance direction, the cutter position B being a position between the first discharge roller 85 and the second discharge roller 86 in the conveyance direction; a sheet detection sensor SE4 that detects whether the sheet S exists at a first detection position between the first discharge roller 85 and the second discharge roller 86 in the conveyance direction; a discharge sensor SE3 that detects whether the sheet S exists at a second detection position between the first discharge roller 85 and the fixing device 6 in the conveyance direction; and a CPU 101.

[0241] Then, the CPU 101 executes: a conveyance process (S218, S220) in which, in the conveyance process of conveying the sheet S along the conveyance path 201 using the conveyance rollers 35, 36, 85 to 87, based on the detection results of the sheet detection sensor SE4 and the discharge sensor SE3, the rotation amounts of the first discharge roller 85 and the second discharge roller 86 for causing the ideal cutting position CP of the sheet S passing through a part of the conveyance path 201 to reach the cutter position B are corrected, and after the first discharge roller 85 and the second discharge roller 86 are rotated by the corrected rotation amounts, the first discharge roller 85 and the second discharge roller 86 are stopped; and a cutting process (S222) in which, after the conveyance process, the sheet S is cut in the cutting direction using the cutter 10.

[0242] Thus, in the printer 1 of the present embodiment, based on the detection results of the sheet detection sensor SE4 and the discharge sensor SE3, the rotation amounts of the first discharge roller 85 and the second discharge roller 86 for causing the ideal cutting position CP of the sheet S to reach the cutter position B are corrected, the first discharge roller 85 and the second discharge roller 86 are stopped after being rotated by the corrected rotation amounts, and the sheet Sa is cut at the stop position. Therefore, even if the sheet S shrinks due to the heat applied to the sheet S by the fixing device 6, the sheet Sa can be cut at the desired cutting position.

[0243] Incidentally, in the present embodiment, the heating roller 61 is an example of a "heating rotating body". The pressure roller 62 is an example of a "pressing rotating body". The CPU 101 is an example of a "control unit". The sheet detection sensor SE4 is an example of a "first sensor". The discharge sensor SE3 is an example of a "second sensor".

[0244] Further, it is characterized in that, in the conveyance process, the CPU 101 obtains a first time (S212) when the leading end of the sheet S reaches the first detection position based on the detection result of the sheet detection sensor SE4, and obtains a second time (S216) when the trailing end of the sheet S reaches the second detection position based on the detection result of the discharge sensor SE3, and corrects the rotation amounts of the first discharge roller 85 and the second discharge roller 86 based on the obtained first time and second time.

[0245] Thus, since the sheet length of the sheet S is actually measured, even if the sheet S shrinks due to the heat applied to the sheet S by the fixing device 6, the sheet Sa can be cut at a desired cutting position.

[0246] Further, the printer 1 further includes: a main motor 108 that drives either the heating roller 61 or the pressure roller 62 included in the fixing device 6 to rotate; and a discharge motor 109 that drives the first discharge roller 85 and the second discharge roller 86 to rotate. And it is characterized in that the CPU 101 controls the main motor 108 and the discharge motor 109 such that the rotation speed of the discharge motor 109 is faster than the rotation speed of the main motor 108.

[0247] Thus, even if the sheet S is deflected in the fixing device 6, since the conveyance speed of the sheet S is increased by the first discharge roller 85 and the second discharge roller 86, the deflection of the sheet S can be eliminated.

[0248] Further, the printer 1 further includes an NVRAM 104. And it is characterized in that a first rotation amount of the first discharge roller 85 and the second discharge roller 86 required to convey the sheet S from the first detection position of the sheet detection sensor SE4 to the second detection position of the discharge sensor SE3 is stored in advance in the NVRAM 104 as a first rotation amount. In the conveyance process, the CPU 101 obtains a rotation amount of the first discharge roller 85 and the second discharge roller 86 required from the first time to the second time as a second rotation amount, obtains the sheet length in the conveyance direction of the sheet Sa after passing through the fixing device 6 based on the first rotation amount and the second rotation amount, determines the cutting position on the sheet S according to the obtained sheet length, and stops the rotational drive of the discharge motor 109. Incidentally, the NVRAM 104 is an example of a "memory".

[0249] Accordingly, it is not necessary to actually measure a predetermined fixed value, so that the length of the sheet Sa in the conveying direction can be obtained more accurately.

[0250] In addition, it is characterized in that the CPU 101 performs the following control: after obtaining the second moment, the discharge motor 109 is driven to rotate until the cutting position CPa on the determined sheet Sa reaches the cutter position B.

[0251] Accordingly, the conveyance of the sheet Sa can be stopped in a state where the cutting position CPa on the determined sheet Sa reaches the cutter position B.

[0252] In addition, it is characterized in that the discharge motor 109 is a stepping motor, and the CPU 101 controls the stop moment of the discharge motor 109 by the number of steps of the stepping motor.

[0253] Accordingly, the stop moment of the discharge motor 109 can be controlled by a simple method of counting the number of steps of the stepping motor.

[0254] In addition, it is characterized in that the sheet detection sensor SE4 is located on the upstream side in the conveying direction with respect to the cutter position B, the first rotation amount is represented by the number of steps of the stepping motor, and the rotation amount of the first discharge roller 85 and the second discharge roller 86 required to convey the sheet S from the first detection position of the sheet detection sensor SE4 to the cutter position B is stored in advance in the NVRAM 104 as the third rotation amount, and the third rotation amount is represented by the number of steps of the stepping motor. During the conveying process, the CPU 101 obtains the second rotation amount by the number of steps of the stepping motor, and after obtaining the second moment, performs the following control:

[0255] The discharge motor 109 is driven to rotate by {the first rotation amount - (the first rotation amount + the second rotation amount) / 2 + the third rotation amount}.

[0256] Accordingly, even if the sheet S shrinks due to the heat applied to the sheet S by the fixing device 6, it is possible to accurately cut at the center in the conveying direction of the sheet Sa by a simple method of counting the number of steps of the stepping motor.

[0257] In addition, the apparatus main body 2 includes: a first discharge path 201A which is a part of the conveyance path 201 and is configured to discharge the sheet S to the outside of the apparatus main body 2 via the cutter position B; a second discharge path 201B which is a part of the conveyance path 201 and is a path different from the first discharge path 201A and is configured to discharge the sheet S to the outside of the apparatus main body 2; and a shutter 88 which guides the sheet S to either the first discharge path 201A or the second discharge path 201B. Further, the CPU 101 receives a printing job including information on whether it is necessary to cut the sheet using the cutter 10, and when it is determined based on the printing job that sheet cutting is necessary, moves the position of the shutter 88 so as to guide the sheet S to the first discharge path 201A, and when it is determined based on the printing job that sheet cutting is not necessary, moves the position of the shutter 88 so as to guide the sheet S to the second discharge path 201B.

[0258] Accordingly, when sheet S cutting is necessary, the sheet S is guided to the first discharge path 201A by the shutter 88, and when sheet S cutting is not necessary, the sheet S is guided to the second discharge path 201B by the shutter 88, which is convenient.

[0259] (Fourth Embodiment)

[0260] Next, a fourth embodiment of the present invention will be described. Since this embodiment is configured by changing the installation position of the sheet detection sensor SE4 described in the third embodiment, the description will focus on the changed part, and the description of other parts will be appropriately omitted. In addition, the hardware of this embodiment is substantially used as is Figures 1 to 3 and Figure 17 the described hardware, but in order to clarify the installation position of the sheet detection sensor SE4a of this embodiment, a cross-sectional view of Figure 24 is used instead of Figure 1 and Figure 17 . However, in Figure 24 , for components identical to Figure 1 and Figure 17 , the same reference numerals are assigned.

[0261] Relative to Figure 17 , the sheet detection sensor SE4 is provided between the first discharge roller 85 and the cutter position B, Figure 24 , the sheet detection sensor SE4a is provided between the cutter position B and the second discharge roller 86. Due to this difference in the installation position, a part of the sheet conveyance process to the cutter position in Figure 20 needs to be changed.

[0262] Figure 25 Shows the detailed steps of the sheet conveying process to the cutter position executed by the CPU 101 of this embodiment. In Figure 25 , the same step numbers are assigned to the same processes as Figure 20 , and the description of this process is appropriately omitted.

[0263] In Figure 25 , the CPU 101 calculates the number of STEPs (S240) from the cutting position CP of the sheet S to the cutter position B in the conveying path 201 and the first discharge path 201A by the following formula (3).

[0264] Number of sheet length STEPs / 2 - Measured number of STEPs - Number of STEPs from the cutter position B to the sheet detection sensor SE4... (3)

[0265] Figure 26 Is a diagram for explaining the process of S240, showing the state where the rear end of the sheet Sa reaches the detection position of the discharge sensor SE3. At this time, the measured number of STEPs determined in S232 is 80 STEPs. That is, the number of STEPs from the front end of the sheet Sa being detected by the sheet detection sensor SE4 to the rear end of the sheet Sa being detected by the discharge sensor SE3 is 80 STEPs. And since the length X1 from the discharge sensor SE3 to the sheet detection sensor SE4 is a fixed established value, that is, 260 STEPs, the number of STEPs of the sheet length in the conveying direction of the sheet Sa can be calculated as 260 + 80 = 340 STEPs. In addition, for example, when the length X1 is pre-stored in the NVRAM 104, it can be read and used. When the number of STEPs of the sheet length is calculated in this way, its cutting position CPa is calculated as the number of STEPs of the sheet length / 2. Specifically, the cutting position CPa = 170 STEPs. And since the length X1 = 260 STEPs, the cutting position CPa is located 90 STEPs ( = 260 - 170) upstream from the detection position of the sheet detection sensor SE4. Furthermore, the length Y1 from the cutter position B to the detection position of the sheet detection sensor SE4 is a fixed established value, that is, 20 STEPs. Therefore, if the sheet Sa is conveyed in such a way that the cutting position CPa moves 70 STEPs ( = 90 - 20) downstream from the current position ( = 170 STEPs), the cutting position CPa reaches the cutter position B. That is, formula (3) represents the number of STEPs from the rear end of the sheet Sa reaching the detection position of the discharge sensor SE3 to the cutting position CPa of the sheet Sa reaching the cutter position B.

[0266] As described above, in the printer 1 of the present embodiment, the sheet detection sensor SE4a is located on the downstream side in the conveyance direction with respect to the cutter position B, the first rotation amount is represented by the number of steps of the stepping motor, and the rotation amounts of the first discharge roller 85 and the second discharge roller 86 required to convey the sheet S from the cutter position B to the first detection position of the sheet detection sensor SE4a are stored in advance in the NVRAM 104 as the third rotation amount, and the third rotation amount is represented by the number of steps of the stepping motor. Then, it is characterized in that, in the conveyance process, the CPU 101 acquires the second rotation amount by the number of steps of the stepping motor, and after acquiring the second time, performs the following control:

[0267] Drive the discharge motor 109 to rotate {the first rotation amount - (the first rotation amount + the second rotation amount) / 2 - the third rotation amount}. Incidentally, the sheet detection sensor SE4a is an example of the "first sensor".

[0268] Thus, even if the sheet S shrinks due to the heat applied to the sheet S by the fixing device 6, it is possible to correctly cut at the center in the conveyance direction of the sheet Sa by a simple method of counting the number of steps of the stepping motor.

[0269] In addition, the present invention is not limited to each embodiment, and various changes can be made without departing from the gist thereof.

[0270] (1) In each embodiment, the detection positions where the pre-alignment sensor SE1, the post-alignment sensor SE2, the discharge sensor SE3, and the sheet detection sensor SE4 detect the passage of the sheet S are almost the same as the installation positions of the respective sensors, but this is not limited thereto, and sensors with the installation positions of the sensors separated from the detection positions of the sheet S can also be used.

[0271] (2) In Embodiments 1 and 2, the sheet detection sensor SE4 is arranged between the cutter position B and the second discharge roller 86, but this is not limited thereto, and it can also be arranged between the first discharge roller 85 and the cutter position B.

[0272] (3) In each embodiment, as an example of the image forming apparatus, the monochrome laser printer 1 has been described, but this is not limited thereto, and it can also be a color laser printer.

[0273] (4) In each embodiment, the case of cutting the sheet P in half has been described, but this is not limited thereto, and the sheet P can also be cut, for example, into three equal parts.

[0274] (5) In each embodiment, when receiving a print job from the outside of the printer 1, it is received via the communication I / F 130, but this is not limited thereto, and for example, it can also be received via a USB interface.

[0275] (6)In each embodiment, the sheet detection sensor SE4 also serves as an opening / closing detector for the cover 23 and detects the sheet, but different detection sensors may also be used.

[0276] (7)In each embodiment, when the sheet detection sensor SE4 does not detect the sheet even after a predetermined time has elapsed since the start of driving of the discharge motor 109, it is determined that there is a jam, but it may also be configured not to make such a determination. For example, it may be a configuration in which the output of the sheet detection sensor SE4 is used only to convey the sheet S until the cutting position CP of the sheet S reaches the cutter position B. Conversely, it may also be a configuration in which the sheet S is conveyed until the cutting position CP of the sheet S reaches the cutter position B without using the output of the sheet detection sensor SE4, and the sheet detection sensor SE4 is used only when it is determined that there is a jam when the sheet detection sensor SE4 does not detect the sheet even after a predetermined time has elapsed since the start of driving of the discharge motor 109.

[0277] (8)In each embodiment, the printer 1 is configured to be able to cut a sheet S of A4 size and letter size at the center of the sheet, but for example, it may not be able to cut A4 size and may only be able to cut a sheet S of letter size. In this case, the length of the conveyance path 201 from the nip N in Figure 1 to the cutter position B and the length of the conveyance path 201 from the nip of the roller 36 to the cutter position B only need to be designed to be longer than half (139.7 mm) of the size (279.4 mm) in the conveyance direction of the letter size. Furthermore, it may also be able to cut a sheet of a size larger than A4 size.

[0278] (9)In each embodiment, the cutter 10 is composed of a moving blade 15 and a fixed blade 13, but as long as it can cut the sheet S, regardless of the shape and type. For example, it may also be a structure or scissors that cut the sheet by dropping a blade that is long in the cutting direction onto the sheet S.

[0279] Reference Signs

[0280] 1... Printer, 2... Apparatus main body, 6... Fixer, 10... Cutter, 61... Heating roller, 62... Pressing 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... Conveyance path, 201A... First discharge path, 201B... Second discharge path, B... Cutter position, SE3... Discharge sensor, SE4, SE4a... Sheet detection sensor.

Claims

1. An image forming apparatus, characterized in that, Comprising: A device main body having a conveyance path for a sheet; A fixing device having a heating rotating body and a pressing rotating body, and fixing an image formed on the sheet to the sheet, with a nip formed between the pressing rotating body and the heating rotating body; A first discharge roller located downstream of the fixing device in the conveyance direction of the sheet along the conveyance path, and conveying the sheet; A second discharge roller located downstream of the first discharge roller in the conveyance direction, and discharging the sheet conveyed by the first discharge roller to the outside of the device main body; A cutter located at a cutter position and capable of cutting the sheet in a cutting direction crossing the conveyance direction, the cutter position being a position between the first discharge roller and the second discharge roller in the conveyance direction; And A first sensor for detecting whether the sheet exists at a first detection position between the first discharge roller and the second discharge roller in the conveyance direction.

2. The image forming apparatus according to claim 1, characterized in that It further comprises a control unit, The control unit performs: A conveyance process, based on the output of the first sensor, driving the first discharge roller and the second discharge roller with a driving amount required to convey 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 stopping the conveyance of the sheet; And A cutting process, after the conveyance process, cutting the sheet in the cutting direction using the cutter.

3. The image forming apparatus according to claim 2, characterized in that The control unit performs a driving amount acquisition process, receives print data including the sheet size of the sheet, and acquires the driving amount based on the sheet size included in the received print data, In the conveyance process, after driving the first discharge roller and the second discharge roller with the driving amount acquired through the driving amount acquisition process, the control unit stops the conveyance of the sheet.

4. The image forming apparatus according to claim 2, characterized in that It further comprises a second sensor for detecting whether the sheet exists at a second detection position upstream of the first sensor in the conveyance direction, The control unit performs: A sheet length acquisition process, based on the output of the second sensor, detecting the situation from when the front end of the sheet reaches the second detection position until the rear end of the sheet reaches the second detection position, and acquiring the sheet length of the sheet in the conveyance direction based on the detected front end and rear end of the sheet; And A driving amount acquisition process, acquiring a driving amount based on the sheet length acquired through the sheet length acquisition process, In the conveyance process, after driving the first discharge roller and the second discharge roller with the driving amount acquired through the driving amount acquisition process, the conveyance of the sheet is stopped.

5. The image forming apparatus according to claim 4, characterized in that In the sheet length acquisition process, the control unit acquires the length of the sheet in the conveyance direction of the sheet based on the output of the second sensor and based on the conveyance amount of the sheet from when the front end of the sheet is detected until the rear end of the sheet is detected.

6. The image forming apparatus according to claim 2, wherein: it further includes a discharge motor that drives the first discharge roller and the second discharge roller, in the conveyance process, when the first sensor does not detect the sheet even after a predetermined time has elapsed since the start of driving the discharge motor, the control unit stops driving the discharge motor.

7. The image forming apparatus according to claim 6, wherein: it further includes a main motor that drives either the heating rotating body or the pressing rotating body to rotate, in the conveyance process, when the first sensor does not detect the sheet even after the predetermined time has elapsed since the start of driving the discharge motor, the control unit also stops driving the main motor.

8. The image forming apparatus according to claim 6 or 7, wherein: the apparatus main body further has a display panel, in the conveyance process, when the first sensor does not detect the sheet even after the predetermined time has elapsed since the start of driving the discharge motor, the control unit displays a notification screen notifying that a jam has occurred on the display panel.

9. The image forming apparatus according to claim 2, wherein: it further includes a discharge motor that drives the first discharge roller and the second discharge roller, after the cutting process, the control unit performs a discharge process, drives the first discharge roller and the second discharge roller, and discharges the cut sheet to the outside of the apparatus main body, in the discharge process, when the first sensor detects the sheet even after a predetermined time has elapsed since the start of driving the discharge motor, the control unit stops driving the discharge motor.

10. The image forming apparatus according to claim 9, wherein: the apparatus main body further has a display panel, in the discharge process, when the first sensor does not detect the sheet even after the predetermined time has elapsed since the start of driving the discharge motor, the control unit causes a notification screen notifying that a jam has occurred to be displayed on the display panel.

11. The image forming apparatus according to claim 9 or 10, wherein: the cutter has a blade for cutting the sheet and a cutting motor that moves the blade in the cutting direction, in the cutting process, when the cutting motor is in a driving state and the discharge motor is in a non-driving state, and when the state changes from the first sensor detecting the sheet to the first sensor not detecting the sheet, the control unit stops driving the cutting motor.

12. The image forming apparatus according to claim 1, wherein: The first sensor detects whether the sheet is present at a detection position between the cutter and the second discharge roller.

13. The image forming apparatus according to claim 1, wherein it further includes a cover that opens and closes to cover the conveyance path between the first discharge roller and the second discharge roller, the first sensor outputs a first signal when the cover is in an open state and when the cover is in a closed state and the sheet is detected, and outputs a second signal when the cover is in a closed state and the sheet is not detected, when the sheet is not conveyed through the first discharge roller and the second discharge roller, when the first signal is output from the first sensor, the control unit determines that the cover is in an open state.

14. The image forming apparatus according to claim 1, wherein it further includes a third discharge roller that is located on a discharge path branching from the conveyance path between the fuser and the first discharge roller and is located at a position shorter than the length of the conveyance path from the fuser to the second discharge roller, and discharges the sheet to the outside of the apparatus main body, the control unit receives print data including cutting presence / absence information indicating whether the sheet is cut, and when the cutting presence / absence information included in the received print data indicates non-cutting, conveys the sheet through the third discharge roller and discharges the sheet from the apparatus main body to the outside without cutting the sheet.

15. The image forming apparatus according to claim 14, wherein it further includes a stopper that can be switched to a first position for guiding the sheet toward the first discharge roller and a second position for guiding the sheet toward the third discharge roller, when the cutting presence / absence information indicates cutting, before the leading end of the sheet separates from the fuser and reaches the stopper, the control unit switches the stopper to the first position, when the cutting presence / absence information indicates non-cutting, before the leading end of the sheet separates from the fuser and reaches the stopper, the control unit switches the stopper to the second position.

16. The image forming apparatus according to claim 1, wherein the length of the conveyance path from the fuser to the cutter is longer than half of the sheet length in the conveyance direction of the sheet that can be cut.

17. The image forming apparatus according to claim 2, wherein It further includes: a discharge motor that drives the first discharge roller; a roller that is located between the first discharge roller and the fuser; and a main motor that drives the roller and the fuser, the length of the conveyance path from the roller to the cutter is longer than half of the sheet length in the conveyance direction of the sheet that can be cut, the control unit maintains the state of driving the main motor during the cutting process.

18. The image forming apparatus according to claim 1, wherein It also includes an image forming unit that is located upstream of the fuser in the conveying direction and forms an image on the sheet. The image forming unit has a photosensitive drum, a developing roller that supplies toner to the photosensitive drum, and a transfer roller that transfers the toner image formed on the photosensitive drum to the sheet.

19. The image forming apparatus according to claim 1, wherein It further includes: a plurality of conveying rollers including the first discharge roller and the second discharge roller; a second sensor that detects whether the sheet exists at a second detection position between the first discharge roller and the fuser in the conveying direction; and a control unit, The control unit performs: a conveying process in which, in the conveying process of conveying the sheet along the conveying path using the plurality of conveying rollers, based on the detection results of the first sensor and the second sensor, the rotation amounts of the first discharge roller and the second discharge roller for making the cutting position of the ideal sheet passing through a part of the conveying path reach the cutter position are corrected, and after the first discharge roller and the second discharge roller are rotated by the corrected rotation amounts, the first discharge roller and the second discharge roller are stopped; and a cutting process in which, after the conveying process, the sheet is cut along the cutting direction using the cutter.

20. The image forming apparatus according to claim 19, wherein in the conveying process, the control unit, based on the detection result of the first sensor, obtains a first time when the front end of the sheet reaches the first detection position, and based on the detection result of the second sensor, obtains a second time when the rear end of the sheet reaches the second detection position, and corrects the rotation amounts of the first discharge roller and the second discharge roller based on the obtained first time and second time.

21. The image forming apparatus according to claim 20, wherein, It further includes: a main motor that drives either the heating rotating body or the pressing rotating body included in the fuser to rotate; and a discharge motor that drives the first discharge roller and the second discharge roller to rotate, The control unit controls the main motor and the discharge motor such that the rotation speed of the discharge motor is faster than the rotation speed of the main motor.

22. The image forming apparatus according to claim 21, wherein it further includes a memory, in the memory, the rotation amounts of the first discharge roller and the second discharge roller required to convey the sheet from the second detection position of the second sensor to the first detection position of the first sensor are pre-stored as a first rotation amount, in the conveying process, the control unit obtains the rotation amounts of the first discharge roller and the second discharge roller required from the first time to the second time as a second rotation amount, obtains the sheet length in the conveying direction of the sheet after passing through the fuser based on the first rotation amount and the second rotation amount, determines the cutting position on the sheet according to the obtained sheet length, and stops the rotational drive of the discharge motor.

23. The image forming apparatus according to claim 22, wherein The control unit performs the following control: After obtaining the second moment, drive the discharge motor to rotate until the determined cutting position on the sheet reaches the cutter position.

24. The image forming apparatus according to claim 22, wherein: The discharge motor is a stepping motor. The control unit controls the stop moment of the discharge motor based on the number of steps of the stepping motor.

25. The image forming apparatus according to claim 24, wherein: The first sensor is located on the upstream side in the conveying direction compared to the cutter position. The first rotation amount is represented by the number of steps of the stepping motor. In the memory, the rotation amount of the first discharge roller and the second discharge roller required to convey the sheet from the first detection position of the first sensor to the cutter position is pre-stored as a third rotation amount, and this third rotation amount is represented by the number of steps of the stepping motor. During the conveying process, the control unit Obtains the second rotation amount based on the number of steps of the stepping motor. After obtaining the second moment, Performs the following control: Drive the discharge motor to rotate {First rotation amount - (First rotation amount + Second rotation amount) / 2 + Third rotation amount}.

26. The image forming apparatus according to claim 24, wherein: The first sensor is located on the downstream side in the conveying direction compared to the cutter position. The first rotation amount is represented by the number of steps of the stepping motor. In the memory, the rotation amount of the first discharge roller and the second discharge roller required to convey the sheet from the cutter position to the first detection position of the first sensor is pre-stored as a third rotation amount, and this third rotation amount is represented by the number of steps of the stepping motor. During the conveying process, the control unit Obtains the second rotation amount based on the number of steps of the stepping motor. After obtaining the second moment, Performs the following control: Drive the discharge motor to rotate {First rotation amount - (First rotation amount + Second rotation amount) / 2 - Third rotation amount}.

27. The image forming apparatus according to claim 19, wherein: The apparatus main body has: A first discharge path, which is a part of the conveying path and is used to discharge the sheet to the outside of the apparatus main body via the cutter position. A second discharge path, which is a part of the conveying path and is a path different from the first discharge path, and is used to discharge the sheet to the outside of the apparatus main body. And A shutter that guides the sheet to either the first discharge path or the second discharge path. The control unit receives a printing job including information related to whether it is necessary to cut the sheet using the cutter. When it is determined based on the printing job that sheet cutting is required, the control unit moves the position of the shutter so as to guide the sheet to the first discharge path. In the case where it is determined based on the printing job that the sheet does not need to be cut, the control unit moves the position of the shutter so as to guide the sheet to the second discharge path.

Images