Image forming device

Abstract

To shorten the operation time for cutting a sheet-like medium again.SOLUTION: A printer comprises: a conveyance unit which conveys a roll sheet; a cutting unit which includes a stationary blade, a rotary blade and a movement mechanism that moves the rotary blade and can cut the roll sheet; a current value output circuit which outputs a current value of a motor for moving the rotary blade; and a control unit. The control unit determines if the printer is in a normal state where the roll sheet is normally cut, a first abnormal state where there is an abnormality in cutting or a second abnormal state where there is an abnormality different from the first abnormal state in cutting on the basis of a signal output from the current value output circuit when the roll sheet is cut by moving the rotary blade from a standby position to the right side, and executes a retry operation of cutting the roll sheet by moving the rotary blade to the left side from a stop position when determining that the printer is in the first abnormal state.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus having a cutting unit capable of cutting sheet media. [Background technology]

[0002] Patent document 1 describes a technology in which, when a movable blade is moved relative to a fixed blade to cut recording paper (sheet-like media), fluctuations in the current of the cutter motor that moves the movable blade are detected to determine whether the recording paper is present between the movable blade and the fixed blade, and if it is determined that the recording paper is not between the blades, it is determined that the recording paper cannot be transported between the blades and a paper jam has occurred. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-7592 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 can determine whether a paper jam has occurred, but cannot determine whether the recording paper has been cut properly. Therefore, even if it determines that the recording paper is between the blades and has been cut, there is a risk that the recording paper will be discharged even if it is not actually cut properly (for example, if the recording paper is only partially cut or if the recording paper is caught and wrinkled during cutting).

[0005] The present inventors have developed a technique for determining whether a sheet medium has been cut normally, but have found the following problems. When cutting a sheet medium, if it is determined that there is an abnormality in the cutting of the sheet medium, returning the blade to the specified position before cutting and then cutting the sheet medium again takes time, which increases the operating time required to cut the sheet medium again.

[0006] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an image forming apparatus that can shorten the operation time required to re-cut the sheet medium. [Means for solving the problem]

[0007] The image forming apparatus of the present invention has a conveying unit that conveys sheet-like media in a conveying direction, an image forming unit that forms an image on the sheet-like media conveyed by the conveying unit, a first blade that can contact one side of the sheet-like media conveyed by the conveying unit, a second blade that can contact the other side of the sheet-like media, a moving mechanism that moves at least one of the first blade and the second blade in a direction intersecting the conveying direction, and a cutting unit in which the first blade and the second blade work together to cut the sheet-like media in the intersecting direction, a signal output unit that outputs a determination signal that indicates the change in the moving load on at least one of the blades over time when the sheet-like media is cut by the cutting unit, and a control unit. The control unit is capable of performing a state determination process that, when cutting the sheet medium by moving at least one of the blades in a first direction that is parallel to the intersecting direction and extends from one end of the sheet medium to the other end of the intersecting direction, determines whether the sheet medium is in a normal state in which it has been cut normally, or an abnormal state in which there is an abnormality in the cutting, based on the determination signal output from the signal output unit, and a retry process that cuts the sheet medium by moving at least one of the blades in a second direction opposite to the first direction if the abnormal state is determined in the state determination process. [Effects of the Invention]

[0008] According to the image forming apparatus of the present invention, if the control unit determines in the state determination process that there is an abnormality in the cutting of the sheet medium, it executes a retry process to cut the sheet medium by moving at least one of the blades in the second direction, thereby shortening the operation time to re-cut the sheet medium. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a side view showing a schematic configuration of a printer according to an embodiment of the present invention; [Figure 2] FIG. 2 is a block diagram of a control unit of the printer shown in FIG. [Figure 3] FIG. 4 is a side cross-sectional view showing the detailed configuration of the cover and the cutting portion. [Figure 4] 2A and 2B are schematic plan views of the cutting section shown in FIG. 1, where (a) shows the rotary blade and carriage positioned in the standby position, (b) shows the rotary blade and carriage positioned in the stop position, and (c) shows the situation in which a second abnormal state occurs when cutting roll paper. [Figure 5] 2A and 2B show the change in current value over time when roll paper is cut at the cutting section shown in FIG. 1, where (a) shows a normal state, (b) shows a first abnormal state, and (c) shows a second abnormal state. [Figure 6] 10A is a cross-sectional view showing a state in which the roll paper is cut normally, and FIG. 10B is a cross-sectional view showing a state in which the roll paper is cut abnormally in a first abnormal state. [Figure 7] 10 is a flowchart showing an example of a processing procedure executed when the printer shown in FIG. 1 receives a roll image formation signal. [Figure 8] 10A and 10B show the change in the moving speed of the rotary blade over time when cutting roll paper in the cutting section of a modified printer, where (a) is a diagram showing the normal state, (b) is a diagram showing the first abnormal state, and (c) is a diagram showing the second abnormal state. DETAILED DESCRIPTION OF THE INVENTION

[0010] A printer 1 according to a preferred embodiment of the present invention will be described below with reference to the drawings. In the following description, the up-down direction is defined based on the state in which the printer 1 is installed so that it can be used (the state shown in FIG. 1), the front-rear direction is defined with the side of the housing 11 where the opening 13 is provided as the near side (front or front), and the side where the opening 14 is provided as the far side (back or rear), and the left-right direction is defined when the printer 1 is viewed from the near side.

[0011] As shown in FIG. 1, the printer 1 has a feeding cassette 2, a conveying section 3, a cutting section 5, a head (the "image forming section" of the present invention) 6, an output tray 7, a control section 8, an alarm section 9 (see FIG. 2), a housing 11, a cover 15, a current value output circuit 16 (see FIG. 2), and an encoder 17 (see FIG. 2).

[0012] The feed cassette 2 is disposed below the head 6 within the housing 11. The discharge tray 7 is disposed in front of the head 6 within the housing 11 and above the feed cassette 2. The feed cassette 2 and discharge tray 7 can be inserted into the housing 11 in the front-to-rear direction through an opening 13 provided on the front surface of the housing 11. Furthermore, the feed cassette 2 attached to the housing 11 can be removed in the front-to-rear direction through the opening 13. Furthermore, the discharge tray 7 attached to the housing 11 can be pulled out forward through the opening 13.

[0013] The feed cassette 2 selectively stores either the roll R or the cut sheets Kp so that either the roll R or the cut sheets Kp can be selectively transported. The roll R is a long length of roll paper ("sheet medium" according to the present invention) Rp wound in a roll shape around the outer circumferential surface of a cylindrical core (paper tube) Rc. As shown in FIG. 1, the feed cassette 2 has a tray 21 having a box shape that opens upward, and a support part 22 that supports the outer circumferential surface of the lower part of the roll R and rotatably supports the roll R. The cut sheets Kp are placed on the bottom surface 21b1 of the tray 21 behind the support part 22, or on the entire bottom surface 21b1 when the support part 22 is removed. In the following description, when there is no need to distinguish between the roll paper Rp unwound from the roll R and the cut sheets Kp, they may be referred to as "paper P."

[0014] The support unit 22 has a support base 23 and three rollers 24 to 26. The roll R is supported by the support unit 22 in an orientation in which its axial direction is parallel to the left-right direction (the direction perpendicular to the plane of FIG. 1). The support base 23 is detachably provided on the bottom 21b of the tray 21. The support base 23 extends along the left-right direction. The rollers 24 to 26 are all rotatably supported by the support base 23 in an orientation in which their axial directions are parallel to the left-right direction.

[0015] Support base 23 has horizontal surface 23a and two inclined surfaces 23b, 23c arranged on either side of horizontal surface 23a in the front-to-rear direction. Roller 24 is arranged on the rear side of inclined surface 23b and is arranged forward of roller 25. Roller 25 is arranged on the front side of inclined surface 23c, and roller 26 is arranged on the rear side of inclined surface 23c. Rollers 24, 25 support roll R from below while contacting the outer peripheral surface of the lower part of roll R.

[0016] The cover 15 is disposed in an opening 14 provided on the rear surface of the housing 11. The lower end of the cover 15 is rotatably supported by a shaft 15a supported by the housing 11. The shaft 15a extends in the left-right direction (the direction perpendicular to the plane of the paper in FIG. 1). The cover 15 can be rotated around the shaft 15a to take a closed position (the position shown by the solid line in FIG. 1) and an open position (the position shown by the dashed line in FIG. 1). When the cover 15 is in the closed position, it forms a transport path W for the paper P by the transport unit 3 between itself and a guide (not shown) provided inside the housing 11. When the cover 15 is in the open position, a portion of the transport path W is opened.

[0017] The transport unit 3 has a feed unit 31, three pairs of transport rollers 32 to 34, and a transport motor 35M (see FIG. 2). The feed unit 31 feeds paper P, either the roll R or cut paper Kp stored in the feed cassette 2, rearward from the feed cassette 2.

[0018] The feeding unit 31 is disposed above the feeding cassette 2 and includes a feeding roller 31a, an arm 31b, and a feeding motor 31M (see FIG. 2). The feeding roller 31a is axially supported at the tip of the arm 31b. The arm 31b is rotatably supported on a support shaft 31c. The arm 31b is biased by a spring or the like in a direction in which the feeding roller 31a contacts the bottom surface 21b1 of the tray 21. The arm 31b is also configured to be able to retract upward when the tray 21 is attached or detached. The feeding roller 31a rotates when a driving force is transmitted from the feeding motor 31M. When the feeding motor 31M is driven under the control of the control unit 8, the feeding roller 31a rotates, and the paper P stored in the tray 21 is fed rearward.

[0019] The three transport roller pairs 32 to 34 transport the paper P fed by the feeding unit 31 within the housing 11 along a transport direction perpendicular to the left-right direction. The three transport roller pairs 32 to 34 are arranged in this order from the upstream side in the transport direction. The transport roller pair 32 transports the paper P sent out from the feeding cassette 2 by the feeding unit 31. The paper P transported by the transport roller pair 32 is first sent upward with one side facing backward and the other side facing forward, and then sent forward after passing through the cutting unit 5. The transport roller pair 33 receives the paper P transported by the transport roller pair 32 and sends it to the head 6. The transport roller pair 34 receives the paper P transported by the transport roller pair 33 and discharges it. The paper P transported by the transport roller pairs 33 and 34 is sent forward.

[0020] Each of the conveying roller pairs 32 to 34 is made up of a drive roller that rotates when a driving force is transmitted from the conveying motor 35M, and a driven roller that rotates along with the drive roller. When the conveying motor 35M is driven under the control of the control unit 8, the drive roller and driven roller of the conveying roller pairs 32 to 34 rotate while nipping the paper P, and the paper P is conveyed in the conveying direction.

[0021] 1, the cutting unit 5 is located between the pair of conveying rollers 32, 33 in the conveying direction and above the pair of conveying rollers 32. The cutting unit 5 has a fixed blade 51, a rotary blade 52, and a movement mechanism 53 (see FIG. 4), and the fixed blade 51 and the rotary blade 52 work together to cut the roll paper Rp that passes through a path Wx (part of the conveying path W) between the fixed blade 51 and the cover 15.

[0022] As shown in FIG. 3, fixed blade 51 ("second blade" of the present invention) has a vertical portion 51a and a horizontal portion 51b, and is formed with an L-shaped cross section. Fixed blade 51 is fixed to housing 11. Vertical portion 51a stands upright from the rear end of horizontal portion 51b. Furthermore, as shown in FIG. 4, fixed blade 51 extends elongatedly in the left-right direction. More specifically, fixed blade 51 is formed to be longer than the width of roll paper Rp (width in the direction perpendicular to the conveying direction). Vertical portion 51a of fixed blade 51 is positioned so that it can abut against the front-facing surface of roll paper Rp passing through path Wx (the "other surface" of the present invention).

[0023] When the cover 15 is in the closed position (the position indicated by the solid line in FIG. 1), the rotary blade 52 (the "first blade" of the present invention) is positioned in a groove 15b formed in the front-facing surface of the cover 15. The rotary blade 52 is mounted on a carriage 54 (see FIG. 4), which will be described later and which is movable in the left-right direction. As shown in FIG. 3, the rotary blade 52 is disk-shaped and supported by the carriage 54 so as to be rotatable about a shaft 52a extending in the vertical direction. The rotary blade 52 is also supported by the shaft 52a so as to be rotatable in a state parallel to the left-right direction. The rotary blade 52 is also positioned so as to be able to come into contact with the rear-facing surface (the "one surface" of the present invention) of the roll paper Rp passing through the path Wx. The rotary blade 52 is also positioned so that its front end can come into contact with the upper end surface of the vertical portion 51a of the fixed blade 51.

[0024] As shown in Fig. 4, the movement mechanism 53 has a carriage 54, a belt 55, a pair of pulleys 56 and 57, a guide rail 58 (see Fig. 3), and a movement motor 53M (see Fig. 2). As shown in Fig. 3, the guide rail 58 is disposed in the groove 15b of the cover 15 when the entire cover is in the closed position. The guide rail 58 is formed long in the left-right direction, and supports the carriage 54 so that it can move left-right.

[0025] As shown in FIG. 4, the carriage 54 rotatably supports the rotary blade 52 and is fixed to the belt 55. The pair of pulleys 56, 57 are arranged spaced apart from each other in the left-right direction, sandwiching the path Wx therebetween. The pulley 56 is a drive pulley to which a rotational force is applied by the movement motor 53M. The belt 55 is an endless circular belt that is stretched over the pair of pulleys 56, 57. The pulley 57 is a driven pulley that rotates due to the belt 55 running as the pulley 56 rotates.

[0026] As shown in FIG. 4(a), the carriage 54 is normally positioned in a standby position at the left end of the fixed blade 51. At this time, the rotary blade 52 is also positioned in a standby position. When cutting the roll paper Rp, the control unit 8 controls the movement motor 53M to rotate in the forward direction, causing the belt 55 to move and the rotary blade 52 to move to the right (the "first direction" of the present invention) along with the carriage 54. At this time, the rotary blade 52 rotates due to friction with the fixed blade 51. As a result, the fixed blade 51 and the rotary blade 52 cooperate to cut the roll paper Rp on the path Wx from one end to the other in the width direction of the roll paper Rp (the direction perpendicular to the conveyance direction). In this way, the rear end of the roll paper Rp is formed. After moving to the right, the carriage 54 and rotary blade 52 are stopped at a stop position at the right end of the fixed blade 51 when the movement motor 53M is stopped, as shown in FIG. 4(b). Thereafter, the movement motor 53M is driven to rotate in the reverse direction, whereby the rotary blade 52 moves leftward together with the carriage 54 and is returned to the standby position shown in FIG. 4(a).

[0027] A current value output circuit 16 is connected to the movement motor 53M. The current value output circuit (the "signal output unit" of the present invention) 16 outputs a signal (the "determination signal" of the present invention) indicating the magnitude (current value) of the load on the movement motor 53M (i.e., the movement load on the rotary blade 52) when moving the rotary blade 52 in the left-right direction. In addition, an encoder 17 is provided at the portion of a transmission mechanism (not shown) that transmits the rotational force applied from the movement motor 53M to the pulley 56. The encoder 17 outputs a signal indicating the position to which the rotary blade 52 has moved from the standby position due to the rotation of the movement motor 53M, and the movement speed during that movement. In this embodiment, a rotary encoder is used as the encoder 17, but a linear encoder may also be used.

[0028] When the rotary blade 52 is moved from the standby position to the stop position to cut the roll paper Rp, if the roll paper Rp is successfully cut, the current value output circuit 16 outputs a current value such as that shown in FIG. 5(a). More specifically, the current value increases while the carriage 54 is moved rightward from the standby position and accelerated to a predetermined speed. Then, as the carriage 54 reaches the predetermined speed and becomes constant, the current value fluctuates near a predetermined value C (e.g., 0.6 A). While the carriage 54 is moving at a constant speed, the roll paper Rp comes into contact with the rotary blade 52, and the fixed blade 51 and rotary blade 52 work together to cut the roll paper Rp from one end to the other in the left-right direction. In a normal state where the roll paper Rp is being cut normally by the fixed blade 51 and rotary blade 52, the current value fluctuates below the first threshold value C1. When the roll paper Rp is cut correctly, as shown in Fig. 6(a), the roll paper Rp is arranged in a vertically linear state and is cut by the rotary blade 52. In this embodiment, the first threshold C1 is set to 110% of the predetermined value C, but this may be changed as needed as long as it is greater than the predetermined value C. Then, when the rotary blade 52 passes the other end of the roll paper Rp, the carriage 54 is decelerated, and the current value decreases until it comes to a stop, as shown in Fig. 5(a).

[0029] Meanwhile, between the time when the rotary blade 52 passes one end of the roll paper Rp and the time when it passes the other end of the roll paper Rp, for some reason, such as deterioration of the paper quality or the blade, the roll paper Rp may not be cut by the fixed blade 51 and the rotary blade 52, and the roll paper Rp may become pinched between the fixed blade 51 and the rotary blade 52, as shown in FIG. 6(b), resulting in a first abnormal state (the "abnormal state" of the present invention) in which there is an abnormality in the cutting of the roll paper Rp. While this first abnormal state occurs, as shown in FIG. 5(b), there is a period Ta during which the cut value exceeds the first threshold value C1 but is equal to or less than the second threshold value C2. In this embodiment, the second threshold value C2 is set to 150% of the predetermined value C, but may be changed as long as it is greater than the first threshold value C1.

[0030] Furthermore, as shown in FIG. 4(c), due to some reason, such as paper quality or blade deterioration, the roll paper Rp is not cut by the fixed blade 51 and rotary blade 52 before the rotary blade 52 passes the other end of the roll paper Rp. Instead, the roll paper Rp is pushed to the right by the rotary blade 52, causing it to bend. This prevents the rotary blade 52 from moving, resulting in a second abnormal state (the "abnormal state" of the present invention) in the cutting of the roll paper Rp, which is different from the first abnormal state. When this second abnormal state occurs, the second threshold C2 is exceeded, as shown in FIG. 5(c). The second abnormal state described above can also occur if a foreign object that prevents the rotary blade 52 from moving is caught between the carriage 54 and the guide rail 58 or between the rotary blade 52 and the fixed blade 51.

[0031] In this way, in this embodiment, when cutting the roll paper Rp, the signal output from the current value output circuit 16 varies greatly depending on the cutting state of the roll paper Rp. This is used in this embodiment to determine whether an abnormality has occurred in the cutting of the roll paper Rp, as will be described later.

[0032] The head (the "image forming unit" of the present invention) 6 is disposed between the pair of transport rollers 33 and the pair of transport rollers 34. The head 6 includes a plurality of nozzles (not shown) formed on its underside and a driver IC 6a (see FIG. 2). When the driver IC 6a is driven under the control of the control unit 8, the head 6 ejects ink supplied from an ink cartridge (not shown) from the nozzles to form an image on the paper P transported by the pair of transport rollers 33. The paper P on which the image has been formed is transported forward (to the left in FIG. 1) by the pair of transport rollers 34. The head 6 may be either a line-type head that ejects ink from nozzles while remaining fixed in position, or a serial-type head that ejects ink from nozzles while moving left and right (in the main scanning direction).

[0033] The discharge tray 7 receives the paper P transported forward by the transport roller pair 34. The paper P stored in the discharge tray 7 is roll paper Rp whose rear end has been formed by the cutting section 5 and on which an image has been formed by the head 6, and cut paper Kp on which an image has been formed by the head 6.

[0034] The notification unit 9 is for performing a notification operation to notify the user of information. The notification unit 9 is, for example, a display provided in the printer 1, and performs the notification operation to the user by displaying the information to be notified to the user. Alternatively, the notification unit 9 is a speaker provided in the printer 1, and performs the notification operation to the user by emitting the information to be notified to the user by voice.

[0035] Next, with reference to FIG. 2, the control unit 8, which controls the entire printer 1, will be described. The control unit 8 includes a central processing unit (CPU) 81, a read-only memory (ROM) 82, a random access memory (RAM) 83, an application-specific integrated circuit (ASIC) 84, a flash memory 85, and other components connected to one another via a bus. These components work together to control the operation of the driver IC 6a, the feed motor 31M, the transport motor 35M, the movement motor 53M, the notification unit 9, and other components. A signal indicating a current value is input to the control unit 8 from a current value output circuit 16. A signal indicating the position of the rotary blade 52 (carriage 54) and the horizontal movement speed of the rotary blade 52 is also input to the control unit 8 from an encoder 17.

[0036] The control unit 8 may be configured such that only the CPU 81 performs various processes, or such that only the ASIC 84 performs various processes, or such that the CPU 81 and the ASIC 84 work together to perform various processes. The control unit 8 may be configured such that one CPU 81 performs processes independently, or such that multiple CPUs 81 share the processes. The control unit 8 may be configured such that one ASIC 84 performs processes independently, or such that multiple ASICs 84 share the processes.

[0037] <Control of roll paper printing> Next, we will explain the control by the control unit 8 during roll paper printing, which forms an image on roll paper Rp. When the printer 1 receives a roll image formation signal to execute roll paper printing, the control unit 8 performs processing according to the flow in Figure 7. The roll image formation signal is a signal that instructs the printer 1 to form an image on roll paper Rp, and is sent to the control unit 8 from an external device or the like.

[0038] Explaining the flow of FIG. 7 in more detail, the control unit 8 first determines whether or not a roll image formation signal has been received (S1). If the roll image formation signal has not been received (S1: NO), S1 is repeated. If the roll image formation signal has been received (S1: YES), the control unit 8 starts roll paper printing (S2). That is, the control unit 8 causes the conveyance unit 3 to convey the roll paper Rp from the feed cassette 2 in the conveyance direction. Then, the head 6 forms an image on the roll paper Rp conveyed by the conveyance unit 3.

[0039] Next, the control unit 8 determines whether the cut portion of the roll paper Rp has been transported to the cutting position of the cutting unit 5 (the upper end surface of the vertical portion 51a of the fixed blade 51) (S3). The cut portion of the roll paper Rp is derived based on the roll image formation signal received by the control unit 8. If the cut portion of the roll paper Rp has not been transported to the cutting position (S3: NO), roll paper printing continues (S4) and the process returns to S3. On the other hand, if the cut portion of the roll paper Rp has been transported to the cutting position (S3: YES), the control unit 8 temporarily halts roll paper printing and proceeds to S5.

[0040] In S5, the control unit 8 starts cutting the roll paper Rp (S5). That is, the control unit 8 drives the movement motor 53M to rotate forward, moving the carriage 54 and the rotary blade 52 from the standby position toward the stop position (i.e., to the right). At this time, the control unit 8 controls the movement motor 53M so that the movement speed of the carriage 54 and the rotary blade 52 accelerates from the standby position until it reaches a first predetermined speed, and then moves at the first predetermined speed. At this time, the control unit 8 also stores current value information in the flash memory 85 based on a signal from the current value output circuit 16. At this time, if previous current value information is stored in the flash memory 85, it overwrites it with the current current value information. The current value information is information about changes in current value over time, as shown in FIG. 5.

[0041] Next, the control unit 8 determines whether the current value from when cutting of the roll paper Rp begins until the rotary blade 52 passes the other end of the roll paper Rp (the end closer to the stop position) exceeds the second threshold C2 (S6: "state determination process" of the present invention). If the current value exceeds the second threshold C2 (S6: YES), the control unit 8 determines that a second abnormal state has occurred and stops cutting the roll paper Rp (S7). That is, in S7, the control unit 8 controls the movement motor 53M to return the rotary blade 52 to the standby position. Thereafter, the control unit 8 causes the notification unit 9 to perform a notification operation to notify the user that a second abnormal state in which movement of the rotary blade 52 is obstructed is likely to have occurred (S8). This ends the flow.

[0042] On the other hand, if the current value is equal to or less than the second threshold C2 (S6: NO), the control unit 8 determines whether the rotary blade 52 has passed the other end of the roll paper Rp based on the signal from the encoder 17 (S9). If the rotary blade 52 has not passed the other end of the roll paper Rp (S9: NO), the process returns to S6. On the other hand, if the rotary blade 52 has passed the other end of the roll paper Rp (S9: YES), the control unit 8 controls the movement motor 53M to stop the rotary blade 52 at the stop position, and ends cutting of the roll paper Rp (S10).

[0043] Next, the control unit 8 determines whether the period Ta is equal to or greater than a predetermined period from the current value information stored in the flash memory 85 (S11: "status determination process" of the present invention). If the period Ta is less than the predetermined period during the current cutting operation of the roll paper Rp (S11: NO), such as when the period Ta does not exist or when the period Ta exists but is extremely short, the control unit 8 determines that the cutting of the roll paper Rp is normal and proceeds to S12.

[0044] Next, in S12, the control unit 8 resumes roll paper printing, which had been temporarily stopped, on the roll paper Rp whose trailing edge has been formed by cutting, and ejects the roll paper Rp on which the image has been formed. At this time, if a retry flag is stored in the flash memory 85, the control unit 8 clears the retry flag. This ends the flow.

[0045] On the other hand, if the period Ta is equal to or longer than the predetermined period in the current cutting operation of the roll paper Rp (S11: YES), the control unit 8 determines that the first abnormal state has occurred, and proceeds to S13.

[0046] In S13, the control unit 8 determines whether or not a retry flag is stored in the flash memory 85. If a retry flag is stored (S13: YES), the control unit 8 causes the notification unit 9 to execute a notification operation to notify the user that a first abnormal state is likely to have occurred (S14). At this time, the control unit 8 erases the retry flag stored in the flash memory 85. The flow then ends.

[0047] On the other hand, if a retry flag is not stored (S13: YES), the process proceeds to S15. In S15, the control unit 8 controls the transport motor 35M to transport the roll paper Rp a predetermined distance. For example, if the head 6 is a serial head, the head 6 is moved left and right to transport the roll paper Rp in the transport direction the distance required for one pass of forming an image on the roll paper Rp. The predetermined distance for transporting the roll paper Rp in S15 can be set appropriately as long as it is shorter than the length of the roll paper Rp in the transport direction after an image is formed based on the roll image formation signal and ejected. By transporting the roll paper Rp a predetermined distance in this way, it is possible to shift the cutting location of the roll paper Rp during the retry operation (described below). In other words, it is possible to cut the roll paper Rp at a new location on the roll paper Rp during the retry operation. This makes it possible to cut the roll paper Rp away from areas of the roll paper Rp that are difficult to cut.

[0048] Next, the control unit 8 executes a retry operation (S16: "retry process" of the present invention). The retry operation refers to an operation in which the carriage 54 is moved in the opposite direction from that in S5 to cut the roll paper Rp again. That is, the control unit 8 drives the movement motor 53M to rotate in the reverse direction, and moves the rotary blade 52 together with the carriage 54, which was stopped at the stop position in S10, toward the standby position (i.e., to the left (the "second direction" of the present invention)). At this time, the control unit 8 controls the movement motor 53M so that the movement speed of the carriage 54 and the rotary blade 52 accelerates from the stop position until it reaches a second predetermined speed that is faster than the first predetermined speed, and then moves at the second predetermined speed. At this time, the control unit 8 also stores a retry flag in the flash memory 85. At this time, the control unit 8 also overwrites the current value information from the current value output circuit 16 in the flash memory 85.

[0049] Next, the control unit 8 again determines whether the current value from when cutting of the roll paper Rp begins until the rotary blade 52 passes one end of the roll paper Rp (the end on the standby position side) exceeds the second threshold C2 (S17: "retry state determination process" of the present invention). If the current value exceeds the second threshold C2 (S17: YES), the control unit 8 determines that a second abnormal state has occurred and stops cutting the roll paper Rp (S18). That is, in S18, the control unit 8 controls the movement motor 53M to return the rotary blade 52 to the stop position. After this, the control unit 8 proceeds to S8 and ends the flow.

[0050] On the other hand, if the current value is equal to or less than the second threshold C2 (S17: NO), the control unit 8 determines whether the rotary blade 52 has passed one end of the roll paper Rp based on the signal from the encoder 17 (S19). If the rotary blade 52 has not passed one end of the roll paper Rp (S19: NO), the process returns to S17. On the other hand, if the rotary blade 52 has passed one end of the roll paper Rp (S19: YES), the control unit 8 proceeds to S10. After this, the process proceeds to S11, where, as described above, the control unit 8 determines whether the period Ta is equal to or greater than a predetermined period based on the current value information stored in the flash memory 85 (the "retry status determination process" of the present invention). If the period Ta is less than the predetermined period during the current retry operation of the roll paper Rp (S11: NO), such as when the period Ta does not exist or, even if it does exist, it is an extremely short period, the control unit 8 determines that the cutting of the roll paper Rp is normal, proceeds to S12, and ends the flow. On the other hand, if the period Ta is equal to or longer than the predetermined period in the current retry operation for the roll paper Rp (S11: YES), the control unit 8 determines that the first abnormal state has occurred, proceeds to S13 and S14, and ends the flow.

[0051] As described above, in the printer 1 of this embodiment, if the control unit 8 determines in S11 that a first abnormal state has occurred, meaning that an abnormality has occurred in the cutting of the roll paper Rp, it executes a retry operation to cut the roll paper Rp by moving the rotary blade 52 leftward from the stop position toward the standby position. By executing a retry operation in this manner, it is possible to shorten the operation time required to re-cut the roll paper Rp, compared to once returning the rotary blade 52 from the stop position to the standby position and then moving it from the standby position toward the stop position. Furthermore, the control unit 8 executes a retry operation when it determines that a first abnormal state has occurred. This allows the retry operation to be executed effectively.

[0052] Furthermore, when it is determined in S6 that the second abnormal state exists, the control unit 8 causes the notification unit 9 to perform the notification operation in S8. This makes it possible to notify the user that there is a high possibility that the movement of the rotary blade 52 is being obstructed when the second abnormal state exists.

[0053] Furthermore, if the control unit 8 determines in S17 after the retry operation in S16 that the second abnormal state has occurred, it causes the control unit 8 to execute an announcing operation in S8, and if it determines in S11 that the first abnormal state has occurred, it causes the control unit 8 to execute an announcing operation in S14. This makes it possible to determine the cut state of the roll paper Rp in S17 and S11 when a retry operation is performed. Then, when either the first abnormal state or the second abnormal state has occurred, the announcing unit 9 executes an announcing operation to notify the user that the abnormal state is likely to have occurred.

[0054] Furthermore, the control unit 8 determines in S6 that the second abnormal state has occurred when the current value exceeds the second threshold C2, determines in S11 that the state is normal when the period Ta is less than a predetermined period, and determines in S11 that the state is first abnormal when the period Ta is equal to or greater than the predetermined period. This makes it possible to determine the movement state of the rotary blade 52 and the cutting state of the roll paper Rp based on the current value of the movement motor 53M.

[0055] Furthermore, in the retry operation of S16, the control unit 8 makes the movement speed of the carriage 54 and rotary blade 52 for cutting the roll paper Rp faster than the movement speed in S5, thereby making it possible to shorten the operation time for the retry operation.

[0056] In the above embodiment, the control unit 8 determines whether the roll paper Rp is cut based on the current value signal from the current value output circuit 16. However, as a modified example, this determination may be based on a signal indicating the position and movement speed (the "determination signal" of the present invention) from the encoder 17. In this modified example, the current value output circuit 16 does not need to be provided.

[0057] In this modified example, when the rotary blade 52 is moved from the standby position to the stop position to cut the roll paper Rp, if the roll paper Rp is successfully cut, the encoder 17 outputs the movement speed shown in FIG. 8(a). When cutting the roll paper Rp, the control unit 8 moves the carriage 54 to the right from the standby position and accelerates it until it reaches a predetermined speed V. Once the carriage 54 reaches the predetermined speed V, the control unit 8 moves it at a constant speed. As the roll paper Rp is cut by the fixed blade 51 and the rotary blade 52 in this state, the movement load on the rotary blade 52 appears as a change in the movement speed. Even if there is some change in speed, it remains near the predetermined speed V. In other words, in a normal state where the roll paper Rp is being properly cut by the fixed blade 51 and the rotary blade 52, the movement speed remains above the first threshold V1. Furthermore, although the first threshold V1 in this modified example is set to 90% of the predetermined speed V, it may be changed as long as it is smaller than the predetermined speed V. Then, when the rotary blade 52 passes the other end of the roll paper Rp, the control unit 8 decelerates and stops the carriage 54.

[0058] Meanwhile, the first abnormal state described above may occur between when the rotary blade 52 passes one end of the roll paper Rp and when it passes the other end of the roll paper Rp. When this first abnormal state occurs, a period Tv occurs during which the speed is less than the first threshold value V1 and greater than or equal to the second threshold value V2, as shown in Figure 8(b). In this embodiment, the second threshold value V2 is set to 50% of the predetermined speed V, but may be changed as needed as long as it is smaller than the first threshold value V1.

[0059] Furthermore, the second abnormal state described above may occur before the rotary blade 52 passes the other end of the roll paper Rp. When this second abnormal state occurs, the movement speed becomes less than the second threshold value V2, as shown in FIG. 8(c).

[0060] When cutting the roll paper Rp in this way, the signal output from the encoder 17 varies greatly depending on the cutting state of the roll paper Rp. By utilizing this, it is possible to determine whether an abnormality has occurred in the cutting of the roll paper Rp, just as in the above-described embodiment. By performing the above-described retry operation when the first abnormal state is present, the same effect as in the above-described embodiment can be achieved.

[0061] While the preferred embodiment of the present invention has been described above, the present invention is not limited to the above embodiment and various modifications are possible within the scope of the claims. For example, in the above embodiment, the control unit 8 determines whether the cut state of the roll paper Rp is normal, a first abnormal state, or a second abnormal state. However, it may determine whether the cut state is normal or the first abnormal state as an abnormal state. In other words, it is not necessary to determine the second abnormal state. In this case, the same effect as described above can be obtained.

[0062] Furthermore, in the above-described embodiment, the cutting unit 5 has the fixed blade 51, but instead of the fixed blade 51, a rotary blade that can move in the left-right direction together with the rotary blade 52 may be provided. The rotary blade may be a blade that does not rotate. Furthermore, the fixed blade 51 and the rotary blade 52 may be interchangeable in the front-to-rear direction. In other words, the fixed blade 51 may be disposed behind the rotary blade 52.

[0063] Furthermore, in the above embodiment, in S15, the roll paper Rp is transported a predetermined distance, but S16 may be executed without transporting the roll paper Rp. In other words, the process of S15 does not have to be executed. Furthermore, the movement speed of the carriage 54 and rotary blade 52 in the retry operation of S16 is faster than the movement speed in S5, but it may be equal to or slower than the movement speed in S5. Furthermore, the notification unit 9 does not have to be provided.

[0064] The present invention can be applied not only to inkjet printers, but also to electrophotographic printers equipped with a laser image forming unit in which an electrostatic latent image is formed by exposing a photosensitive member to a laser, or an LED image forming unit in which an electrostatic latent image is formed by exposing a photosensitive member to an LED. Furthermore, the sheet-like medium is not limited to paper, and may be any sheet-like medium such as cloth. [Explanation of symbols]

[0065] 1. Printer (image forming device) 3. Conveyor 5 Cut section 6 head (image forming unit) 8 Control Unit 9. Notification Department 16 Current value output circuit (signal output section) 17 Encoder (signal output section) 51 Fixed blade (2nd blade) 52 Rotary blade (1st blade) 53 Moving mechanism 53M Travel Motor Rp roll paper (sheet media)

Claims

1. a conveying unit that conveys the sheet medium in a conveying direction; an image forming unit that forms an image on the sheet medium transported by the transport unit; a cutting unit including a first blade capable of contacting one side of the sheet medium conveyed by the conveying unit, a second blade capable of contacting the other side of the sheet medium, and a movement mechanism that moves at least one of the first blade and the second blade in a direction intersecting the conveying direction, wherein the first blade and the second blade cooperate to cut the sheet medium in the intersecting direction; a signal output unit that outputs a determination signal indicating a change in the load on the at least one blade over time when the sheet medium is cut by the cutting unit; a control unit, the movement mechanism has a motor that applies power to move the at least one blade, the signal output unit outputs a current value of the motor as the determination signal; The control unit a state determination process for determining, based on the determination signal output from the signal output unit, whether the sheet medium is in a normal state in which it has been cut normally, a first abnormal state in which there is an abnormality in the cutting, or a second abnormal state in which there is an abnormality in the cutting that is different from the first abnormal state, when the sheet medium is cut by moving at least one of the blades in a first direction that is parallel to the intersecting direction and from one end of the sheet medium to the other end in the intersecting direction; a retry process for cutting the sheet medium by moving the at least one blade in a second direction opposite to the first direction; In the state determination process, when the current value does not exceed a first threshold, the normal state is determined; when there is a period in which the current value exceeds the first threshold and is equal to or less than a second threshold that is greater than the first threshold and the current value does not exceed the second threshold, the first abnormal state is determined; and when the current value exceeds the second threshold, the second abnormal state is determined; When the first abnormal state is determined, the image forming apparatus executes the retry process.

2. Further comprising a notification unit capable of performing a notification operation to notify a user, The image forming apparatus according to claim 1, characterized in that, when the control unit determines in the state determination process that the second abnormal state has occurred, it causes the notification unit to execute the notification operation to notify that there is a high possibility that the second abnormal state has occurred.

3. 3. The image forming apparatus according to claim 1, wherein the control unit, when determining in the state determination process that the first abnormal state has occurred, transports the sheet medium a predetermined distance before executing the retry process.

4. Further comprising a notification unit capable of performing a notification operation to notify a user, The control unit a retry state determination process for determining whether the state is the normal state, the first abnormal state, or the second abnormal state based on the determination signal output from the signal output unit after the retry process is executed; An image forming apparatus as described in any one of claims 1 to 3, characterized in that in the retry state determination process, if it is determined that the first abnormal state has occurred, the notification unit executes the notification operation to notify that there is a high possibility that the first abnormal state has occurred, and if it is determined that the second abnormal state has occurred, the notification unit executes the notification operation to notify that there is a high possibility that the second abnormal state has occurred.

5. The image forming apparatus according to any one of claims 1 to 4, characterized in that, in the retry process, the control unit makes the speed at which at least one of the blades moves in the second direction faster than when it moves in the first direction.

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