Printing apparatus

Abstract

To perform more reliably automatic sheet feeding of an installed roll.SOLUTION: A controller switches the state from a state of supplying a sheet from a roll held by a first holding part to a state of supplying a sheet from a roll held by a second holding part. When switching the state, the controller rewinds the sheet that is supplied to the roll held by the first holding part.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a printing apparatus that pulls out and supplies a sheet from a roll around which a continuous sheet is wound.

Background Art

[0002] Patent Document 1 discloses a printing apparatus that can detect the leading edge of a sheet of a mounted roll and automatically feed the sheet. In this apparatus, while rotating the roll in the winding direction opposite to the feeding direction, the leading edge of the sheet is detected by an optical sensor. When the detection is completed, the roll is rotated in the feeding direction, and the sheet peeled off and separated from the roll is fed into the apparatus.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration of Patent Document 1, even if the leading edge of the sheet of the roll can be detected normally, in the subsequent feeding operation, the leading edge of the sheet may not proceed along the normal feeding path, and conveyance failures such as paper jams may occur. Patent Document 1 does not disclose any solution to such problems.

[0005] An object of the present invention is to provide a printing apparatus capable of more reliably performing automatic feeding of a mounted roll.

Means for Solving the Problems

[0006] Therefore, the present invention provides a first holding unit that rotatably holds a roll around which a sheet is wound in a first direction for supplying the sheet and a second direction opposite to the first direction, a first sensor that detects an end portion of the sheet of the roll held by the first holding unit, a second holding unit that rotatably holds a roll around which a sheet is wound in the first direction and the second direction, a second sensor that detects an end portion of the sheet of the roll held by the second holding unit, and a control unit that executes a first automatic paper feeding which is control to rotate the roll in the second direction when the roll is set in the first holding unit, detect an end portion of the sheet of the roll with the first sensor, then change the rotation direction of the roll from the second direction to the first direction and insert the sheet into the first supply port for the first time, and a second automatic paper feeding which is control to rotate the roll in the second direction when the roll is set in the second holding unit, detect an end portion of the sheet of the roll with the second sensor, then change the rotation direction of the roll from the second direction to the first direction and insert the sheet into the second supply port for the first time. The control unit switches from a state in which a sheet is being supplied from the roll held by the first holding unit to a state in which a sheet is being supplied from the roll held by the second holding unit by the second automatic paper feeding, and when switching to the state in which a sheet is being supplied by the second automatic paper feeding, rewinds the sheet being supplied onto the roll held by the first holding unit.

Advantages of the Invention

[0007] According to the present invention, automatic paper feeding of the mounted roll can be performed more reliably.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, the basic configuration of the present invention will be described.

[0010] (Basic Configuration) FIGS. 1 to 6 are explanatory diagrams of the basic configuration of a printing apparatus as an application example of the present invention. The printing apparatus in this example is an inkjet printing apparatus including a sheet supply device for supplying a sheet as a printing medium and a printing unit for printing an image on the sheet. For the sake of explanation, coordinate axes are set as shown in the figure. That is, the sheet width direction of the roll R is the X-axis direction, the direction in which the sheet is conveyed in the printing unit 400 described later is the Y-axis direction, and the gravity direction is the Z-axis direction.

[0011] As shown in FIG. 1, in the printing apparatus 100 of this example, it is possible to set a roll R (roll sheet) in which a sheet 1, which is a long continuous sheet (sometimes referred to as a web), is wound in a roll shape on two roll holding portions, an upper portion and a lower portion. An image is printed on the sheet 1 selectively drawn from those rolls R. The user can input various commands to the printing apparatus 100, such as specifying the size of the sheet 1 and switching between online / offline, by using various switches provided on the operation panel 28.

[0012] FIG. 2 is a schematic cross-sectional view of a main part of the printing apparatus 100. Two sheet feeding devices 200 corresponding to the two rolls R are arranged vertically. The sheet 1 drawn from the roll R by the feeding device 200 is conveyed by a sheet conveying unit (conveying mechanism) 300 along a sheet conveying path to a printing unit 400 where an image can be printed. The printing unit 400 prints an image on the sheet 1 by discharging ink from an inkjet print head 18. The print head 18 discharges ink from a discharge port by using a discharge energy generating element such as an electrothermal conversion element (heater) or a piezo element. The print head 18 is not limited to only the inkjet method, and the printing method of the printing unit 400 is also not limited. For example, it may be a serial scan method or a full line method. In the case of the serial scan method, an image is printed while accompanying the conveyance operation of the sheet 1 and the scanning of the print head 18 in a direction intersecting the conveyance direction of the sheet 1. In the case of the full line method, a long print head 18 extending in a direction intersecting the conveyance direction of the sheet 1 is used, and an image is printed while continuously conveying the sheet 1.

[0013] The roll R is set in the roll holding part of the supply device 200 with the spool member 2 inserted into its hollow hole part, and the spool member 2 is driven to rotate forward and backward by a motor 33 for driving the roll (see Fig. 5). As will be described later, the supply device 200 is provided with a drive part 3, an arm member (moving body) 4, an arm rotating shaft 5, a sensor unit 6, a swing member 7, driven rotating bodies (contact bodies) 8 and 9, a separation flapper (upper guide body) 10, and a flapper rotating shaft 11.

[0014] The conveyance guide 12 guides the front and back surfaces of the sheet 1 drawn out from the supply device 200 and guides the sheet 1 to the printing part 400. The conveyance roller 14 is rotated forward and backward in the directions of arrows D1 and D2 by a motor 35 for driving the conveyance roller (see Fig. 5) described later. The nip roller 15 can be driven to rotate following the rotation of the conveyance roller 14, and can be brought into contact with and separated from the conveyance roller 14 and the nip force can be adjusted by a motor 37 for adjusting the nip force (see Fig. 5). The conveyance speed of the sheet 1 by the conveyance roller 14 is set higher than the pulling-out speed of the sheet 1 by the rotation of the roll R, so that back tension can be applied to the sheet 1 and it can be conveyed while being stretched.

[0015] The platen 17 of the printing part 400 regulates the position of the sheet 1, and the cutter 20 cuts the sheet 1 on which an image has been printed. The cover 42 of the roll R prevents the sheet 1 on which an image has been printed from returning to the supply device 200. The operations in such a printing device 100 are controlled by a CPU 201 (see Fig. 5) described later.

[0016] Fig. 3 is an explanatory view of the supply device 200. The roll R in Fig. 3(a) is in a state where its outer diameter is relatively large.

[0017] On the conveying guide 12, an arm member (moving body) 4 is rotatably attached in the directions of arrows A1 and A2 by a rotating shaft 5. A guide portion 4b (lower guide body) for guiding the lower surface of the sheet 1 drawn from the roll R is formed on the upper portion of the arm member 4. A torsion coil spring 3c that presses the arm member 4 in the direction of arrow A1 is interposed between the arm member 4 and the rotating cam 3a of the drive unit 3. The rotating cam 3a is rotated by a motor (see FIG. 5) 34 for adjusting the pressing force, which will be described later, and the force with which the torsion coil spring 3c presses the arm member 4 in the direction of arrow A1 changes according to the rotational position thereof. As will be described later, when setting the leading end of the sheet 1 into the sheet supply port between the arm member 4 and the separation flapper 10, the pressing force of the arm member 4 by the torsion coil spring 3c is switched in three steps according to the rotational position of the rotating cam 3a. That is, it is switched to a pressing state with a relatively small force (pressing force of a weak nip), a pressing state with a relatively large force (pressing force of a strong nip), and a state of releasing the pressing force.

[0018] A swing member 7 is swingably attached to the arm member 4, and first and second driven rotators (rotating bodies) 8 and 9 that are displaced in the circumferential direction of the roll R are rotatably attached to the swing member 7. These driven rotators 8 and 9 are pressed against the outer peripheral portion of the roll R from below in the direction of gravity by the pressing force in the direction of arrow A1 with respect to the arm member 4. That is, the driven rotators 8 and 9 are pressed against the outer peripheral portion of the roll R from below in the direction of gravity rather than the horizontal central axis of the roll R. The pressing force is changed according to the pressing force that presses the arm member 4 in the direction of arrow A1.

[0019] A plurality of arm members 4 each having a swing member 7 are provided so that their positions in the X-axis direction are different. The swing member 7 is provided with a bearing portion 7a and a shaft retaining portion 7b as shown in FIG. 3(b), and by these, the rotating shaft 4a of the arm member 4 is received with a predetermined amount of play.

[0020] The bearing portion 7a is provided at the center of gravity position of the swing member 7 and is supported by the rotating shaft 4a so that the swing member 7 assumes a stable posture in each of the X-axis direction, Y-axis direction, and Z-axis direction. Further, since the rotating shaft 4a is received with play, the swing member 7 at any position in the X-axis direction is displaced along the outer peripheral portion of the roll R by the pressing force in the direction of arrow A1 with respect to the arm member 4. With such a configuration (equalizing mechanism), changes in the pressure contact postures of the first and second driven rotators 8 and 9 with respect to the outer peripheral portion of the roll R are allowed. As a result, the contact area between the sheet 1 and the first and second driven rotators 8 and 9 is always kept maximum, and the pressing force on the sheet 1 is equalized, suppressing variations in the conveying force of the sheet 1. When the driven rotators 8 and 9 are in pressure contact with the outer peripheral portion of the roll R, the occurrence of slack in the sheet 1 is suppressed and its conveying force is enhanced.

[0021] A separation flapper 10 positioned above the arm member 4 is rotatably attached to the main body (printer main body) of the printing apparatus 100 about a rotating shaft 11 in the directions of arrows B1 and B2. The separation flapper 10 is configured to contact and lightly press the outer peripheral surface of the roll R by its own weight. When it is necessary to press the roll R more strongly, an urging force of an urging member such as a spring may be used. A driven roller 10a is rotatably provided at the contact portion of the separation flapper 10 with the roll R in order to suppress the influence of the pressing force on the sheet 1. Further, the separation portion 10b at the tip of the separation flapper 10 is formed to extend to a position as close as possible to the surface of the roll R in order to facilitate separation of the leading end of the sheet from the roll R.

[0022] Sheet 1 is drawn out from roll R passing over driven rotators 8 and 9, and after its lower surface is guided by guide portion 4b at the upper part of arm member 4, it is supplied through a supply path formed between separation flapper 10 and arm member 4. In this way, driven rotators 8 and 9 are pressed against the outer peripheral portion of roll R from below, and the lower surface of sheet 1 drawn out passing over those driven rotators 8 and 9 is guided by guide portion 4b. Thereby, by utilizing the self-weight of sheet 1, sheet 1 can be supplied smoothly. Also, according to the roll outer diameter of roll R, by the movement of driven rotators 8 and 9 and guide portion 4b, regardless of the outer diameter of roll R, sheet 1 can be reliably drawn out from roll R and conveyed.

[0023] One of the features of the apparatus of this embodiment is the automatic loading function (automatic sheet feeding function) of the sheet. In automatic loading, when the user sets an unused roll R in the apparatus, the apparatus rotates roll R in the direction opposite to the sheet supply time (sheet feeding time) (referred to as the second direction) while detecting the leading end of the sheet. Next, the apparatus rotates roll R in the rotation direction at the time of sheet supply (forward direction or referred to as the first direction), and automatically sends out the leading end of the sheet separated from roll R. Sensor unit 6 detects that the leading end of sheet 1 has peeled off from the outer peripheral surface of roll R and the sheet has been peeled off (sheet separation). The leading end of sheet 1 detected by sensor unit 6 is automatically inserted into and sent out from the sheet supply port between arm member 4 and separation flapper 10. The more detailed procedure of this automatic loading function will be described later.

[0024] Also, in this example, since two supply devices 200, upper and lower, are provided, it is possible to switch from the state of supplying sheet 1 from one supply device 200 to the state of supplying sheet 1 from the other supply device 200. In such a case, one supply device 200 rewinds the sheet 1 that it has been supplying to roll R. The leading end of the sheet 1 is retracted to a position where it is detected by sensor unit 6 or another sheet end sensor provided in the vicinity of sensor unit 6.

[0025] FIG. 4 is an explanatory view of the supply device 200 when the outer diameter of the roll R is relatively small.

[0026] Since the arm member 4 is always pressed in the direction of arrow A1 by the torsion coil spring 3c, it rotates in the direction of arrow A1 as the outer diameter of the roll R decreases. Further, by rotating the rotary cam 3 in accordance with the change in the outer diameter of the roll R, the pressing force of the arm member 4 by the torsion coil spring 3c can be maintained within a predetermined range regardless of the change in the outer diameter of the roll R. Also, since the separation flapper 10 is always pressed in the direction of arrow B1, it rotates in the direction of arrow B1 as the outer diameter of the roll R decreases. As a result, the separation flapper 10 forms a supply path between itself and the conveyance guide 12 even when the outer diameter of the roll R becomes small, and guides the upper surface of the sheet 1 by the lower surface 10c. In this way, as the outer diameter of the roll R changes, the arm member 4 and the separation flapper 10 rotate, so that a supply path of substantially constant size is formed between them regardless of the outer diameter of the roll R.

[0027] FIG. 5 is a block diagram for explaining a configuration example of a control system in the printing apparatus 100. The CPU 201 of the printing apparatus 100 controls each part of the printing apparatus 100 including the supply apparatus 200, the sheet conveyance unit 300, and the printing unit 400 in accordance with a control program stored in the ROM 204. To the CPU 201, information such as the type, width, and various setting information of the sheet 1 is input via the input interface 202 from the operation panel 28. Further, the CPU 201 is connected to various external devices 29 including a host device such as a personal computer via the external interface 205, and exchanges various information such as print data with the external devices 29. Also, the CPU 201 writes to and reads from the RAM 203 information such as information regarding the sheet 1. The motor 33 is a motor for driving the roll R forward and backward via the spool member 2, and constitutes a drive mechanism (rotation mechanism) capable of rotationally driving the roll R. The motor 34 for pressing force adjustment is a motor that rotates the rotary cam 3a to adjust the pressing force on the arm member 4, and the motor 35 for conveyance roller drive is a motor for rotating the conveyance roller 14 forward and backward. The roll sensor 32 is a sensor for detecting the spool member 2 of the roll R when the roll R is set in the supply apparatus 200. The roll rotation amount sensor 36 is a sensor for detecting the rotation amount of the roll R, and is, for example, a rotary encoder that outputs a number of pulses corresponding to the rotation amount of the roll R.

[0028] FIG. 6 is a flowchart for explaining the sheet supply preparation process starting from the setting of the roll R.

[0029] The CPU 201 of the printing device 100 waits in a state where the arm member 4 is pressed in the direction of arrow A1 by a "weak nip pressing force" (weak nip state). First, it determines whether the roll R has been set (step S1). In this example, when the roll sensor 32 detects the spool member 2 of the roll R, it is determined that the roll R has been set. After the roll R is set, the CPU 201 switches to a state where the arm member 4 is pressed in the direction of arrow A1 by a "strong nip pressing force" (strong nip state) (step S2). Next, it executes a sheet leading edge setting process for inserting the leading edge of the sheet 1 into the sheet supply port between the arm member 4 and the separation flapper 10 (step S3). By this sheet leading edge setting process (automatic loading), the leading edge of the sheet 1 is inserted into the supply port. More detailed movements will be described later.

[0030] Thereafter, the CPU 201 rotates the roll R in the direction of arrow C1 by a motor 33 for driving the roll (see FIG. 5) to start supplying the sheet 1 (step S4). When the leading edge of the sheet 1 is detected by the sheet sensor 16 (step S5), the CPU 201 rotates the conveyance roller 14 forward in the direction of arrow D1, picks up the leading edge of the sheet 1, and then stops the motor 33 and the motor 35 (step S6). Thereafter, the CPU 201 releases the pressing force for pressing the arm member 4 in the direction of arrow A1 and separates the first and second driven rotators 8 and 9 from the roll R (nip release state) (step S7).

[0031] Thereafter, the CPU 201 detects whether the sheet is conveyed (skewed) while being obliquely inclined within the sheet conveyance unit 300. Specifically, the sheet 1 is conveyed by a predetermined amount within the sheet conveyance unit 300, and the amount of skew generated at that time is detected by a carriage mounting the print head 18 or a sensor provided in the sheet conveyance unit 300. When the amount of skew is greater than a predetermined allowable amount, while applying back tension to the sheet 1, the forward and reverse rotations of the conveyance roller 14 and the roll R are repeated to feed and backfeed the sheet 1. By such an operation, the skew of the sheet 1 is corrected (step S8). Thus, when correcting the skew of the sheet 1 and when performing the image printing operation on the sheet 1, by setting the supply device 200 in a nip release state, the influence of the driven rotators 8 and 9 on the skew correction accuracy of the sheet 1 and the image printing accuracy can be avoided. Thereafter, the CPU 201 moves the leading end of the sheet 1 to a standby position (fixed position) before the start of printing in the printing unit 400 by the sheet conveyance unit 300 (step S9). Thereby, the supply preparation of the sheet 1 is completed. Thereafter, the sheet 1 is pulled out from the roll R with the rotation of the roll R and conveyed to the printing unit 400 by the sheet conveyance unit 300.

[0032] Hereinafter, as an embodiment of the present invention, the sheet leading end setting process (step S3) in FIG. 5 in the basic configuration of such a printing apparatus 100 will be described.

[0033] (First Embodiment) FIG. 7 is a detailed view of the sensor unit 6 used in the present embodiment. The sensor unit 6 is provided with an optical sensor 60 including a light emitting part 6c such as an LED, an OLED, and an LD, and a light receiving part 6d such as a photodiode. The light receiving part 6d detects the light emitted from the light emitting part 6c and reflected by the downward surface of the roll sheet (the outer surface of the sheet that was the outer peripheral surface of the roll and the surface to be printed by the printing unit). At this time, the shorter the distance between the optical sensor 60 and the roll sheet, the larger the amount of light received by the light receiving part 6d and the larger the output value. Conversely, the longer the distance, the smaller the amount of light received by the light receiving part 6d and the smaller the output value of the sensor 60.

[0034] Here, consider the case where the CPU 201 rotates the roll R clockwise (C2 direction) while detecting the output of the optical sensor 60 under the above configuration. At this time, after the leading edge F of the sheet disengages from the driven roller 10a of the separation flapper 10 and drops onto the arm member 4, it passes through the detection position of the optical sensor 60 on the sensor unit 6. In the present embodiment, the leading edge of the sheet 1 is detected by detecting the change in the detection output of the optical sensor 60 at this time.

[0035] Specifically, as the roll R rotates in the C2 direction, when the leading edge F of the sheet 1 passes through the driven roller 10a of the separation flapper 10 and drops onto the arm member 4, the optical sensor 60 and the surface of the sheet 1 that it detects rapidly approach, and the output value of the optical sensor 60 changes from a low value to a high value. As the roll R further rotates in the C2 direction, a high output value is maintained for a while, but when the leading edge F of the sheet eventually passes through the detection position of the optical sensor 60, the distance between the optical sensor 60 and the surface of the sheet 1 that it detects widens again, and the output value of the optical sensor 60 shifts to a low value. The CPU 201 determines whether the leading edge F of the sheet has passed by detecting such a change in the output value in association with the rotation amount detected by the roll rotation amount sensor 36. Thereafter, the CPU 201 feeds the sheet 1 into the supply port with the leading edge F of the sheet detected by the above method at the head.

[0036] Figs. 8(a) to (c) are diagrams showing various feeding states of the sheet 1 during feeding. Also, Figs. 9(a) and (b) are diagrams showing the output value V of the sensor unit 6 corresponding to each of the feeding states shown in Figs. 8(a) to (c). In Figs. 9(a) and (b), the horizontal axis represents the rotation angle θ of the roll R, and the vertical axis represents the output value V of the optical sensor 60.

[0037] Figure 8(a) shows a state in which the sheet S is being normally fed along the arm member 4. In Figure 8(a), the sheet 1 advances along the conveyance guide 12 while being supported by it, and no sheet jam is caused. At this time, the sheet 1 advances to a position close to the optical sensor 60, and its output value V is maintained at a high value as shown by the broken line L0 in Figures 9(a) and (b).

[0038] Figure 8(b) shows a state in which the leading end F of the sheet is bent or damaged and abuts against the driven roller 10a, and the fed sheet 1 is buckled. The sheet 1A shown by the solid line in Figure 8(b) is lifted above the arm member 4 and is separated from the sensor unit 6 compared to Figure 8(a). In this case, the output value V of the sensor unit 6 is maintained at a low value after a certain rotation angle as shown by the solid line L1 in Figure 9(a). In the present embodiment, when detecting an output change such as the solid line L1 of the sensor unit 6, the CPU 201 determines that there is a concern that a sheet jam may occur.

[0039] On the other hand, in Figure 8(b), a part of the sheet 1B shown by the dotted line is in a position close to the sensor unit 6 while buckling. In this case, the output value V of the optical sensor 60 is maintained at a high value, and it is impossible to distinguish from normal feeding as shown in Figure 8(a) based on the output value at this time. However, if the roll R is further rotated in the C1 direction from this state, the sheet 1B changes to a bellows state as shown by the sheet 1C in Figure 8(c).

[0040] When the bellows-shaped sheet 1C advances as the roll R rotates, the distance between the optical sensor 60 and the sheet 1 increases and decreases. For this reason, the output value V of the optical sensor 60 repeats increasing and decreasing fluctuations after a certain rotation angle as shown by the solid line L2 in Figure 9(b). Therefore, in the present embodiment, even when detecting an output change such as the solid line L2 during feeding, it is determined that there is a concern that a sheet jam may occur.

[0041] FIG. 10 is a flowchart for explaining a specific process executed by the CPU 201 in the sheet leading edge setting process shown in step S3 of FIG. 6. This process mainly consists of an edge detection step for detecting the edge of sheet 1 and a determination step (jam detection step) for determining the feeding state of sheet 1 with the detected edge as the leading edge.

[0042] When this process is started, the CPU 201 first starts detecting the output of the optical sensor 60 in step S101. Next, the CPU 201 proceeds to step S102 and starts rotating the roll R in the C2 direction. Specifically, the roll driving motor 33 is driven while counting the rotation amount of the roll R with the roll rotation amount sensor 36, and the roll R is rotated at a constant speed in the winding direction, that is, the C2 direction in the figure.

[0043] Next, the CPU 201 proceeds to step S103 and determines whether the output value V of the optical sensor 60 has switched from Low to High with respect to a predetermined threshold value T0. Here, switching from Low to High means that the leading edge F of the sheet has come off the driven roller 10a of the separation flapper 10 and has fallen onto the arm member 4. The CPU 201 continues to detect the output of the optical sensor 60 until such a switch from Low to High is confirmed. If it is determined in step S103 that the determination result of the optical sensor 60 has switched from Low to High, the CPU proceeds to step S104.

[0044] Furthermore, in step S104, the CPU 201 determines whether the output value V of the optical sensor 60 has switched from High to Low with respect to the threshold value T0. Here, switching from High to Low means that the leading edge F of the sheet has passed over the sensor unit 6. The CPU 201 continues to detect the output of the optical sensor 60 until such a switch from High to Low is confirmed. If, in step S104, it is determined that the determination result of the optical sensor 60 has switched from High to Low, the CPU proceeds to step S105, determines that the leading edge F of the sheet has been detected, and stores the current rotation angle in the RAM 203. Then, it proceeds to step S106 and stops the rotation of the roll R in the C2 direction.

[0045] Next, the CPU 201 proceeds to step S107 and resets the counter N (N = 0). The counter N is a variable for counting the number of times the output value of the optical sensor 60 fluctuates beyond a predetermined threshold value since the start of the feeding operation.

[0046] In step S108, the CPU 201 starts the rotation of the roll R in the forward direction (C1 direction in the figure). Specifically, the roll rotation amount sensor 36 drives the roll driving motor 33 while counting the rotation amount of the roll R, and rotates the roll R in the feeding direction, that is, the C1 direction in the figure. As a result, the sheet 1 advances between the arm member 4 and the separation flapper 10 with the leading edge F of the sheet detected in step S105 at the head.

[0047] In step S109, the CPU 201 determines whether the rotation amount has exceeded a predetermined rotation amount since the start of the rotation of the roll R in step S108. Here, the predetermined rotation amount is the rotation amount at which it can be considered that the sheet 1 has normally reached within the sheet supply port when no conveyance abnormality of the sheet 1 is detected. If it is determined that the rotation amount has exceeded the predetermined rotation amount, the CPU 201 ends the output detection of the optical sensor 60 in step S117 and ends this process, that is, the leading edge setting process (step S3 in FIG. 6). On the other hand, if the rotation amount has not exceeded the predetermined rotation amount in step S109, the CPU 201 proceeds to step S110.

[0048] In step S110, the CPU 201 determines whether the output value V of the optical sensor 60 is included in the range between a predetermined threshold value T1 and a threshold value T2. In the present embodiment, the threshold values T1 and T2 are threshold values for determining whether the sheet 1 is in a buckled state such as the solid line 1A shown in FIG. 8(b).

[0049] As the roll R rotates in the C1 direction, when the sheet 1 passing over the sensor unit 6 changes to a state such as the solid line 1A, the sensor 60 and the sheet 1 shift from a proximity state to a separated state, and the sensor output value decreases. In the present embodiment, the upper limit threshold value T2 is the sensor output value at which, if it drops below this value, it is regarded as the separated state. The method for setting the threshold value T2 is not particularly limited, and for example, the following method can be adopted.

[0050] First, as shown in FIG. 11(a), an output value Fv obtained when the sensor 60 detects the outer peripheral surface of the roll R before the leading edge F of the sheet reaches the detection area of the sensor 60 is acquired in advance. Also, as shown in FIG. 11(b), an output value Nv obtained when the sensor 60 detects the surface of the sheet 1 being normally conveyed after the leading edge F of the sheet has passed through the detection area of the sensor 60 is acquired in advance. Then, using these, the lower limit threshold value T2 is calculated according to the following formula. T2 = (Fv + Nv) / 2 × 0.2

[0051] Here, it is set in consideration of fluctuations of about 20% of the output value due to the meandering and floating of the sheet 1 with respect to the average value of Fv and Nv.

[0052] On the other hand, regarding the output value V of the optical sensor 60 while rotating the roll R, even if the sheet 1 is advancing normally, the output value V may suddenly fluctuate due to an impact caused by disturbance or the like as shown in FIG. 12. In this case, although the output value V drops rapidly, it recovers early and is independent of the conveyance state of the sheet 1, and it is preferable that the output fluctuation is ignored. Therefore, in the present embodiment, the sensor output value for determining that the output value V has dropped too far below the upper limit threshold value T2 and is a disturbance fluctuation is set as the lower limit threshold value T1. The lower limit threshold value T1 is not particularly limited, but can be set using, for example, the following formula. T1 = Fv × 0.8

[0053] Here, within the range of normal conveyance, for the lowest Fv that can be assumed, the output value reduced by 20% further is set as the threshold value T1 for distinguishing from a disturbance. In this way, in the present embodiment, in order to reliably detect a buckling state such as the solid line L1 in FIG. 9(a) while excluding sudden fluctuations due to disturbance as shown in FIG. 12, the threshold values T1 and T2 are prepared.

[0054] Return to the flowchart of FIG. 10. When the output value V satisfies T1 < V < T2 in step S110, the CPU 201 determines that the sheet 1 is in a buckling state (jamming state), and jumps to step S115. Then, after stopping the rotation of the roll R, it proceeds to step S116 and executes predetermined error processing. Specifically, the leading end of the sheet 1 cannot be set normally, and it is displayed on the display of the operation panel that there is a feeding failure, prompting the user to check the sheet 1.

[0055] On the other hand, when the output value V does not satisfy T1 < V < T2 in step S110, the CPU 201 proceeds to step S111, and uses threshold values T3 and T4 different from the threshold values T1 and T2 to determine whether the sheet 1 is in a bellows state like the solid line 1C shown in FIG. 8(c).

[0056] When the sheet 1 advances in a bellows state like the solid line 1C, the optical sensor 60 and the sheet 1 repeatedly approach and separate from each other. Therefore, in the present embodiment, a lower limit threshold value T3 for determining separation and an upper limit threshold value T4 for determining proximity are prepared, and when they fluctuate a predetermined number of times (Tn) between them, it is determined that the sheet 1 is in a bellows state. At this time, the lower limit threshold value T3 is preferably set to a value larger than the upper limit threshold value T2 for discriminating the buckling state described above. Here, these threshold values T3 and T4 are set according to the following formula. T3=(Fv+Nv)×0.2 T4=(Fv+Nv)×0.4

[0057] Return to the flowchart of FIG. 10. In step S111, the CPU 201 determines whether the sensor output value V satisfies T3>V. When T3>V is not satisfied, it is considered that no sheet jam has occurred at present, and the CPU 201 returns to step S109 to continue detecting the output of the sensor. On the other hand, when the sensor output value V satisfies T3>V, the CPU 201 proceeds to step S112.

[0058] In step S112, the CPU 201 determines whether the counter N exceeds a predetermined count threshold value Tn. If not, it proceeds to step S113, waits for the roll R to rotate by a predetermined rotation angle, and then determines whether the output value V satisfies T4<V. When T4<V, the CPU 201 considers that one valley in the bellows (that is, the state of T3>V and the state of T4<V) has been confirmed, proceeds to S114, and increments the counter N. Then, it returns to step S109 to continue detecting the output of the sensor. On the other hand, when T4<V is not satisfied, the CPU 201 directly returns to step S109 to continue detecting the output of the sensor.

[0059] When it is determined in step S112 that the counter N has exceeded the counter threshold value Tn, the CPU 201 determines that the sheet 1 is in a bellows state (jam state). Therefore, it jumps to step S115, stops the rotation of the roll R, and then executes a predetermined error process. After that, the output detection of the optical sensor 60 is stopped in step S117. This completes this process.

[0060] According to the present embodiment described above, based on the output value of the optical sensor 60 installed on the arm member 4, it is possible to detect the leading end of the roll sheet R and confirm the state of sheet feeding starting from this leading end. That is, in the sheet leading end setting process before the sheet 1 is guided into the sheet conveyance unit 300 or the conveyance roller 14 is driven, it is possible to detect a sheet jam at an early stage and eliminate it.

[0061] In the above, the method of setting the threshold values T1 to T4 has been exemplified using equations, but the method of setting the threshold values is not limited to the method described above. Also, even when the same optical sensor is used, the reflectance of the sheet varies depending on the type of sheet, and as a result, Fv and Nv also change depending on the type of sheet. Furthermore, the distance between the sensor and the sheet suitable for determining the buckling state and the number of valleys suitable for determining the bellows state also differ depending on the rigidity of the sheet. That is, it is preferable that the threshold values T1 to T4 and the counter threshold value Tn are individually optimized for each type of sheet that can be mounted on the apparatus.

[0062] Also, in the above, as the configuration of the sensor unit 6, the optical sensor 60 including the light emitting unit 6c and the light receiving unit 6d is adopted, but the present invention is not limited to this. For example, the light detected by the light receiving unit 6d does not have to be regular reflected light, and any sensor configuration can be used as long as its output value changes according to the distance from the sheet 1 to be detected. For example, a distance sensor such as an ultrasonic sensor or an electrostatic sensor that non - contact detects the distance to an object can also be used.

[0063] Furthermore, in the above description, based on the output value V of one sensor, the detection of the sheet leading edge F and the determination of a sheet jam were performed. However, the present invention is not limited to such a form. A plurality of sensors may be arranged in the X direction or the Y direction in the sheet sensor unit 6. In this case, by using the output values of these plurality of sensors to detect the sheet leading edge F and determine a sheet jam, the detection of the sheet leading edge F and the determination of a sheet jam can be made more reliable.

[0064] Also, in the above description, the printing apparatus 100 capable of setting two roll sheets has been described as an example. However, of course, the number of roll sheets that can be set is not limited to this. A form in which one roll sheet can be set may be used, or a form in which three or more roll sheets can be set may be used. Furthermore, the present invention is not limited to roll sheets, and it is also possible to determine the occurrence of a jam during the conveyance of a cut sheet from a change in the output value of a sensor.

[0065] Also, the present invention can be widely applied as supply devices for various sheets including paper, film, and cloth, and various sheet processing devices such as a printing apparatus and an image reading apparatus including such a supply device. The image reading apparatus reads a recorded image of a sheet supplied from the supply device by a reading head. Also, the sheet processing device is not limited to only a printing apparatus and an image reading apparatus, and may be any device that performs various processes (processing, coating, irradiation, inspection, etc.) on a sheet supplied from the supply device. When the sheet supply device is configured as an independent device, the device can be provided with a control unit including a CPU. Also, when the sheet supply device is provided in the sheet processing device, at least one of those supply device and the sheet processing device can be provided with a control unit including a CPU.

Explanation of Reference Numerals

[0066] 1 Sheet 60 Optical Sensor 200 Sheet Supply Device 201 CPU R Roll F Sheet End

Claims

[Claim 1] a first holding section that holds a roll around which a sheet is wound so as to be rotatable in a first direction in which the sheet is supplied and in a second direction opposite to the first direction; a first sensor that detects an edge of the sheet of the roll held by the first holding portion; a second holding section that holds a roll around which a sheet is wound so as to be rotatable in the first direction and the second direction; a second sensor that detects an edge of the sheet of the roll held by the second holding portion; a control unit that executes a first automatic sheet feeder that is a control for rotating a roll in the second direction when a roll is set in the first holding unit, detecting an end of a sheet on the roll with the first sensor, and then changing the rotation direction of the roll from the second direction to the first direction to insert a sheet into a first supply port for the first time, and a second automatic sheet feeder that is a control for rotating a roll in the second direction when a roll is set in the second holding unit, detecting an end of a sheet on the roll with the second sensor, and then changing the rotation direction of the roll from the second direction to the first direction to insert a sheet into a second supply port for the first time, The control unit switches from a state in which a sheet is supplied from a roll held by the first holding unit to a state in which a sheet is supplied from the roll held by the second holding unit by the second automatic paper feed, and when switching to a state in which a sheet is supplied by the second automatic paper feed, rewinds the sheet that was being supplied onto the roll held by the first holding unit.

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