Sheet feeding device and printing device

Abstract

To reduce sensor adjustment time.SOLUTION: The present invention provides a sheet feeding device that includes driving means for rotating a roll around which a sheet is wound in a first direction and a second direction, and a sensor whose output changes according to a distance between a detection position facing a peripheral surface of the roll and the peripheral surface of the roll, determines an amplification factor of the sensor based on data consisting of a plurality of output values obtained at different rotation angles while rotating the roll in the second direction by the driving means, in which the data is obtained by changing a plurality of the amplification factors during one rotation of the roll.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a sheet feeding device that draws out and feeds a continuous sheet from a roll around which the sheet is wound, and to a printing apparatus. [Background technology]

[0002] Patent Document 1 discloses a printing device that can detect the leading edge of a sheet on a loaded roll and automatically feed the sheet. In this device, the roll is rotated in the winding direction opposite to the supply direction, and an optical sensor located near the roll detects when the leading edge of the sheet peels off and separates from the roll due to its own weight. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-150106 Summary of the Invention [Problem to be solved by the invention]

[0004] In the sheet feeder provided in the printing apparatus described in Patent Document 1, when the roll sheet is replaced, the optical sensor must be adjusted to detect the leading edge of the sheet peeled from the roll by changing the light intensity on the light-emitting side or the sensitivity on the light-receiving side of the sensor so that a predetermined sensor waveform is output. This sensor adjustment involves changing the amplification value of the light intensity on the light-emitting side or the sensitivity on the light-receiving side, and each time the amplification value is changed, the roll sheet must be rotated two or more times in the winding direction, repeating the rotation operation until the sensor output matches the predetermined waveform. This can take a long time to adjust the sensor.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to shorten the adjustment time of a sensor. [Means for solving the problem]

[0006] In order to achieve the above object, the sheet feeding device of the present invention comprises: a driving means for rotating the roll formed by winding the sheet in a first direction in which the sheet is fed to the conveying path and in a second direction opposite to the first direction; a sensor that outputs an output value according to the distance between a detection position facing the circumferential surface of the roll and the circumferential surface of the roll; Equipped with a sheet feeding device that determines an amplification factor of the sensor based on data consisting of a plurality of output values ​​acquired at different rotation angles while rotating the roll in the second direction by the driving means, The data is obtained by changing the amplification factors during one rotation of the roll. In order to achieve the above object, the printing apparatus of the present invention The sheet feeding device; a printing unit that prints an image on a sheet supplied from the sheet supply device; The present invention is characterized by comprising: [Effects of the Invention]

[0007] Regardless of the remaining amount or type of roll sheet, the sensor can be adjusted by rotating it once, which reduces the time required to adjust the optical sensor that detects sheet peeling. do. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a printing apparatus according to an embodiment of the present invention; [Figure 2] Illustration of a printing device [Figure 3] An explanatory diagram of an arm member of a sheet feeding device [Figure 4] Block diagram for explaining the control system of the printing apparatus [Figure 5] Flowchart of sheet supply preparation process [Figure 6]Sensor unit diagram [Figure 7] Flowchart for explaining sheet leading edge setting processing [Figure 8] Illustrative diagram of changes in sensor output of the sensor unit [Figure 9] Flowchart of sensor output value acquisition processing in the first embodiment [Figure 10] Flowchart for explaining the process of determining the sensor amplification factor [Figure 11] FIG. 10 is an explanatory diagram of a sensor output for each sensor amplification factor in the first embodiment. [Figure 12] 10 is a block diagram of a control system of a printing apparatus according to a second embodiment. [Figure 13] Sensor output diagram of the sensor unit [Figure 14] Flowchart for explaining the process of adjusting the amplification factor of the sensor [Figure 15] Flowchart of sensor amplification factor adjustment processing in the second embodiment [Figure 16] An illustration of the memory space that stores roll installation history DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, with reference to the drawings, a detailed description will be given of an embodiment of the present invention. Note that the dimensions, materials, shapes, and relative positions of the components described in the embodiment may be changed as appropriate depending on the configuration of the device to which the invention is applied and various conditions. In other words, the scope of the present invention is not limited to the following embodiment.

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will now be described with reference to the accompanying drawings. First, a basic configuration of the present invention will be described.

[0011] <Basic configuration> 1 to 4 are explanatory diagrams of the basic configuration of a printing apparatus according to an embodiment of the present invention. The printing apparatus of this embodiment is an inkjet printing apparatus that includes a sheet supply device for supplying sheets as printing media and a printing unit for printing images on the sheets. For ease of explanation, coordinate axes are set as shown in the drawings. That is, the sheet width direction of the roll R is the X-axis direction, the direction in which the sheet is transported in the printing unit 400 (described later) is the Y-axis direction, and the direction of gravity is the Z-axis direction.

[0012] As shown in Fig. 1, the printing apparatus 100 of this embodiment is configured so that rolls R (roll sheets), which are long continuous sheets (sometimes called webs) wound into a roll, can be installed in two roll holders, an upper one and a lower one. An image is printed on a sheet 1 selectively pulled out from the roll R. Using various switches on the operation panel 28, the user can input various commands to the printing apparatus 100, such as specifying the size of the sheet 1 and switching between online and offline.

[0013] FIG. 2 is a schematic cross-sectional view of the main part of the printing apparatus 100. Two sheet supply devices 200 (hereinafter referred to as supply devices) corresponding to two rolls R are arranged one above the other. The sheet 1 drawn from the roll R by the supply devices 200 is transported by a sheet transport section (transport mechanism) 300 along a sheet transport path to a printing section 400 where an image can be printed. The printing unit 400 prints an image on the sheet 1 by ejecting ink from an inkjet print head 18. The print head 18 ejects ink from ejection openings using ejection energy generating elements such as electrothermal conversion elements (heaters) or piezoelectric elements. The print head 18 is not limited to an inkjet type, and the printing type of the printing unit 400 is also not limited, and may be, for example, a serial scan type or a full line type. In the case of the serial scan type, an image is printed by transporting the sheet 1 and scanning the print head 18 in a direction intersecting the transport direction of the sheet 1. In the case of the full line type, an elongated print head 18 extending in a direction intersecting the transport direction of the sheet 1 is used, and an image is printed while the sheet 1 is continuously transported.

[0014] The roll R is set in the roll holding section of the supply device 200 with the spool member 2 inserted in the hollow hole, and the spool member 2 is driven in forward and reverse rotation by a motor 33 (see FIG. 4) which is a drive means for driving the roll. The supply device 200 is equipped with a drive section 3, an arm member (moving body) 4, an arm rotation shaft 5, a sensor unit 6, a swinging member 7, driven rotors (contact bodies) 8 and 9, a separation flapper (upper guide body) 10, and a flapper rotation shaft 11, as will be described later.

[0015] The conveying guide 12 guides the front and back surfaces of the sheet 1 drawn from the supply device 200, and leads the sheet 1 to the printing unit 400. The conveying roller 14 is rotated forward and backward in the directions of arrows D1 and D2 by a motor 35 (see FIG. 4) for driving the conveying roller, which will be described later. The nip roller 15 is rotatable in response to the rotation of the conveying roller 14, and can be moved toward and away from the conveying roller 14 and the nip force can be adjusted by a motor 37 (see FIG. 4) for adjusting the nip force. The conveying speed of the sheet 1 by the conveying roller 14 is set higher than the drawing speed of the sheet 1 by the rotation of the roll R, which applies back tension to the sheet 1 and allows it to be conveyed while kept taut.

[0016] A platen 17 of the printing unit 400 regulates the position of the sheet 1, and a cutter 20 cuts the sheet 1 on which an image has been printed. A cover 42 for the roll R prevents the sheet 1 on which an image has been printed from returning to the supply device 200. Such operations in the printing device 100 are controlled by a CPU 201 (see FIG. 4), which will be described later. The platen 17 is equipped with an adsorption means using negative pressure or electrostatic force, and can adsorb the sheet onto the platen to provide stable support.

[0017] FIG. 3 is an explanatory diagram of the arm member 4 in the supply device 200, and in FIG. 3(a), the roll R has a relatively large outer diameter. An arm member (moving body) 4 is attached to the conveying guide 12 by an arm rotation shaft 5 so as to be rotatable in the directions of arrows A1 and A2. A guide portion 4b (lower guide body) that guides the underside of the sheet 1 pulled out from the roll R is formed on the upper part 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 a rotating cam 3a of the drive unit 3. The rotating cam 3a is rotated by a pressing force adjustment motor 34 (see FIG. 4), 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 depending on the rotation position of the rotating cam 3a. When the leading end of the sheet 1 (a part of the sheet 1 including the leading end) is set in the sheet supply path through the gap 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 between three stages according to the rotational position of the rotating cam 3a. That is, the pressing state can be switched between 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 pressing state where no pressing force is released.

[0018] A swinging member 7 is attached to the arm member 4 so as to be swingable, and the swinging member 7 has first and second driven rotors (rotating bodies) 8 and 9 rotatably mounted thereon, the first and second driven rotors (rotating bodies) 8 and 9 being positioned at different positions in the circumferential direction of the roll R. These driven rotors 8 and 9 move according to the outer shape of the roll R, and press the outer periphery of the roll R from below in the direction of gravity by applying a pressing force in the direction of arrow A1 to the arm member 4. That is, the driven rotors 8 and 9 press the outer periphery of the roll R from below in the direction of gravity relative to 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 swinging member 7, are provided at different positions in the X-axis direction. As shown in Fig. 3(b), the swinging member 7 is provided with a bearing portion 7a and a shaft fastening portion 7b, which receive the rotation shaft 4a of the arm member 4 with a predetermined play.

[0020] The bearing 7a is located at the center of gravity of the oscillating member 7 and is supported by the rotating shaft 4a so that the oscillating member 7 maintains a stable position in the X-axis, Y-axis, and Z-axis directions. Because the rotating shaft 4a is supported with some play, the oscillating member 7, regardless of its position in the X-axis direction, is displaced along the outer periphery of the roll R by the pressing force applied to the arm member 4 in the direction of arrow A1. This configuration (equalizing mechanism) allows the first and second driven rotors 8 and 9 to change their pressing positions against the outer periphery of the roll R. As a result, the contact area between the sheet 1 and the first and second driven rotors 8 and 9 is always maximized, and the pressing force applied to the sheet 1 is equalized, thereby suppressing variations in the conveying force of the sheet 1. The pressing of the driven rotors 8 and 9 against the outer periphery of the roll R prevents the sheet 1 from sagging and increases the conveying force.

[0021] A separation flapper 10 located above the arm member 4 is attached to the main body (printer main body) of the printing device 100 so as to be rotatable around a flapper rotation shaft 11 in the directions of arrows B1 and B2. The separation flapper 10 is configured to abut against and lightly press the outer circumferential surface of the roll R by its own weight. If it is necessary to press the roll R more firmly, a biasing force from a biasing member such as a spring may be used. A driven roller 10a is rotatably provided at the contact point between the separation flapper 10 and the roll R to reduce the effect of the pressing force on the sheet 1. Furthermore, a separation portion 10b at the tip of the separation flapper 10 is formed to extend as close as possible to the surface of the roll R to make it easier to separate the leading edge of the sheet from the roll R.

[0022] The sheet 1 is pulled out from the roll R as it passes over the driven rotors 8 and 9, its underside guided by the guide portion 4b at the top of the arm member 4, and then fed through the feed path formed between the separation flapper 10 and the arm member 4. In this way, the driven rotors 8 and 9 are pressed against the outer periphery of the roll R from below, and the underside of the sheet 1 pulled out as it passes over the driven rotors 8 and 9 is guided by the guide portion 4b. This allows the sheet 1 to be fed smoothly using its own weight. Furthermore, the driven rotors 8 and 9 and the guide portion 4b move in accordance with the outer diameter of the roll R, so that the sheet 1 can be reliably pulled out and fed from the roll R regardless of the outer diameter of the roll R.

[0023] One of the features of the device in this embodiment is the automatic sheet loading function (automatic sheet feeding function). In automatic loading, when a user sets an unused roll R in the device, the device detects the leading edge of the sheet while rotating the roll R in the direction opposite to the sheet supply (sheet feeding) direction (referred to as the reverse direction or second direction, the direction of arrow C2 in FIG. 3(a)). Next, the device rotates the roll R in the rotation direction for sheet supply (referred to as the forward direction or first direction, the direction of arrow C1 in FIG. 3(a)), and automatically feeds out the leading edge of the sheet separated from the roll R. The sensor unit 6 is a unit including a leading edge detection sensor that detects when the leading edge of the sheet 1 is peeled off from the outer peripheral surface of the roll R (sheet separation). The leading edge of the sheet 1 detected by the sensor unit 6 is detected by the arm member 4 and the separation flapper 10. Then, a sheet feeding operation is performed in which the sheet 1 is sent out to the conveying path. The procedure for this automatic loading function will be described in more detail later.

[0024] Furthermore, the printing apparatus 100 of this embodiment is equipped with two supply devices 200, one above the other, and can switch from a state in which the sheet 1 is being supplied from one supply device 200 to a state in which the sheet 1 is being supplied from the other supply device 200. In such a case, one supply device 200 rewinds the sheet 1 that it had been supplying onto the roll R. The leading edge of the sheet 1 is retracted to a position where it can be detected by the sensor unit 6 or another sheet edge sensor provided near the sensor unit 6.

[0025] FIG. 4 is a block diagram illustrating an example of the configuration of a control system in the printing apparatus 100. The CPU 201 of the printing apparatus 100 controls each section of the printing apparatus 100, including the supply device 200, the sheet conveying section 300, and the printing section 400, in accordance with a control program stored in the ROM 204. The type, width, and various setting information of the sheet 1 are input to the CPU 201 from the operation panel 28 via the input / output interface 202. The CPU 201 is also connected to various external devices 29, including host devices such as personal computers, via the external interface 205, and exchanges various information, such as print data, with the external devices 29. The CPU 201 also writes and reads information related to the sheet 1 to and from the RAM 203. The motor 33 is a roll drive motor for rotating the roll R forward and backward via the spool member 2, and constitutes a drive mechanism (rotation mechanism) capable of rotating the roll R. The pressing force adjustment motor 34 is a motor that rotates the rotating cam 3a to adjust the pressing force on the arm member 4, and the transport roller drive motor 35 is a motor that rotates the transport roller 14 forward and reverse. The roll sensor 32 is a sensor that detects the spool member 2 of the roll R when the roll R is set in the supply device 200. The roll rotation amount sensor 36 is a sensor (rotation angle detection sensor) that detects the rotation amount of the spool member 2, i.e., 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.

[0026] <Sheet supply preparation process> FIG. 5 is a flowchart for explaining the supply preparation process for the sheet 1, which starts with setting the roll R.

[0027] The CPU 201 of the printing apparatus 100 waits in a state in which the arm member 4 is pressed in the direction of arrow A1 by a "weak nip pressure" (weak nip state), and first determines whether the roll R has been set (step S1). In this embodiment, when the roll sensor 32 detects the spool member 2 of the roll R, it determines that the roll R has been set. After the roll R has been set, the CPU 201 switches the arm member 4 to a state in which the arm member 4 is pressed in the direction of arrow A1 by a "strong nip pressure" (strong nip state) (step S2). Next, the CPU 201 executes a sheet leading edge setting process to set the leading edge of the sheet 1 between the arm member 4 and the separation flapper 10 into the sheet supply path (step S3). This sheet leading edge setting process (automatic loading) sets (inserts) the leading edge of the sheet 1 into the sheet supply path. The sheet leading edge setting process will be described in detail later.

[0028] Thereafter, the CPU 201 rotates the roll R in the direction of the arrow C1 using the roll driving motor 33, and starts feeding the sheet 1 (step S4). When the leading edge of the sheet 1 is detected by the sensor unit 6 (step S5), the CPU 201 rotates the conveying roller 14 forward in the direction of the arrow D1 to pick up the leading edge of the sheet 1, and then stops the motors 33 and 35 (step S6). Thereafter, the CPU 201 rotates the arm member 4 in the direction of the arrow D1. The pressing force in the A1 direction is released, and the first and second driven rotors 8 and 9 are separated from the roll R (nip release state) (step S7). Thereafter, the CPU 201 determines whether the sheet was conveyed at an angle (skewed) in the sheet conveying section 300. Specifically, the CPU 201 conveys the sheet 1 a predetermined distance in the sheet conveying section 300, and detects the amount of skew that occurs at that time using a carriage that carries the print head 18 or a sensor provided in the sheet conveying section 300. If the amount of skew is greater than a predetermined allowable amount, the CPU 201 applies back tension to the sheet 1 and repeatedly feeds and backfeeds the sheet 1 by rotating the conveying roller 14 and the roll R forward and backward. By performing these operations, the skew of the sheet 1 is corrected (step S8). In this way, by setting the supply device 200 to the nip release state when correcting skew of the sheet 1 and when printing an image on the sheet 1, it is possible to avoid the influence of the driven rotors 8 and 9 on the accuracy of correcting skew of the sheet 1 and the accuracy of printing an image. Thereafter, the CPU 201 causes the sheet conveying unit 300 to move the leading edge of the sheet 1 to a standby position (fixed position) in the printing unit 400 before printing begins (step S9). This completes preparations for supplying the sheet 1. Thereafter, the sheet 1 is pulled out from the roll R as the roll R rotates, and is conveyed to the printing unit 400 by the sheet conveying unit 300.

[0029] The sheet leading edge setting process (step S20) in FIG. 5 in the basic configuration of the printing apparatus 100 will be described.

[0030] The sensor unit 6 uses an optical sensor whose output changes depending on the distance between the sensor unit 6 and the surface (outer surface) of the sheet 1. Then, based on the change in the output of the sensor unit 6 while the roll R is rotating in the reverse direction (the direction of arrow C2), it detects that the leading edge of the sheet 1 has peeled off and separated (separated) from the outer peripheral surface of the roll R, and then the roll R is rotated in the forward direction of arrow C1 to supply the sheet 1.

[0031] As shown in FIG. 6 , the sensor unit 6 of this embodiment incorporates a light-emitting element 6c such as an LED and a light-receiving element 6d such as a photodiode. The light-emitting element 6c emits detection light toward the outer peripheral surface of the roll R, and the light-receiving element 6d receives the detection light reflected by the outer peripheral surface of the roll R and the detection light reflected by the portion of the sheet 1 peeled off from the roll R. The light emitted from the light-emitting element 6c toward the roll R is reflected by the surface of the sheet 1 on the roll R and then detected by the light-receiving element 6d. The light emitted from the light-emitting element 6c and detected by the light-receiving element 6d includes specularly reflected light reflected by the surface of the sheet 1 on the roll R. The output value of the light-receiving element 6d varies depending on the distance (distance) between the sensor unit 6, which is provided at a detection position facing the outer peripheral surface of the roll R, and the downward-facing surface of the sheet 1 (the outer surface of the sheet that was the outer peripheral surface of the roll and is the surface to be printed in the printing unit). In other words, the output value of the light-receiving unit 6d increases as the distance (spacing) between the sensor unit 6 and the surface of the sheet 1 decreases, and decreases as the distance (spacing) increases. Furthermore, locating the sensor unit 6 at a position where the leading edge of the sheet 1 peeled from the roll R is likely to approach and the output value of the light-receiving unit 6d is likely to increase makes it easier to obtain the position of the leading edge of the sheet 1 from the output value. Furthermore, it is necessary to prevent the leading edge of the sheet 1 from sagging into the gap between the driven rotor 8 and the arm member 4 due to its own weight, thereby affecting the nip state of the sheet 1. For this reason, the sensor unit 6 is located between the driven rotor 8 and the separation flapper 10, just before the leading edge of the sheet 1 enters the sheet supply path. The sensor unit 6 may be configured such that the output value of the detection signal changes depending on the distance between the sensor unit 6 and the surface of the sheet 1. The light-emitting unit 6c and the light-receiving unit 6d are not limited to LEDs and photodiodes. The light detected by the light-receiving unit 6d is not limited to specular reflection. The sensor unit 6 is connected to a CPU 201 (see FIG. 4), and the CPU 201 acquires the detection result of the sensor unit 6 at any timing.

[0032] 7 and 8 are explanatory diagrams of the sheet leading edge setting process (step S3 in FIG. 5) using the sensor unit 6. As described above, the sheet leading edge setting process (automatic loading) is a process in which, after the roll R is set, the leading edge of the sheet 1 on the roll R is automatically inserted into the sheet supply path between the arm member 4 and the separation flapper 10, and the sheet 1 is sent out to the conveyance path with the leading edge of the sheet in the lead position. The arm member 4 faces the front surface of the sheet 1 (the outer surface of the sheet), and the separation flapper 10 faces the back surface of the sheet 1 (the inner surface of the sheet).

[0033] Prior to starting the sheet leading edge setting process, the CPU 201 first determines whether the roll R has been set (step S1 in FIG. 5). In this embodiment, when the roll sensor 32 detects the spool member 2 of the roll R, it determines that the roll R has been set. After the roll R has been set, the CPU 201 switches the arm member 4 to a state in which it presses in the direction of arrow A1 with a "strong nip pressing force" (strong nip state) (step S2 in FIG. 5).

[0034] In the subsequent sheet leading edge setting process (step S3 in FIG. 5), the CPU 201 performs a sheet leading edge detection operation using the sensor unit 6 to acquire the position of the leading edge of the sheet peeled off from the outer peripheral surface of the roll R. First, the roll R is rotated (reversely rotated) in the direction of arrow C2 (step S11). Then, during the reverse rotation of the roll R, it is determined whether the output of the detection signal (sensor signal level) of the sensor unit 6 has changed so as to drop from the H level range (within the first level range) to the L level range (within the second level range) (step S12). FIG. 8(a) is an explanatory diagram of an example of a waveform of the sensor output. The rotation angle of the roll R at the start of the reverse rotation of the roll R is set to 0 degrees. Normally, the sensor output is at the L level. When the roll R has rotated 170 degrees in the reverse direction, as shown in FIG. 8(b), the outer surface of the leading edge of the sheet 1 approaches the detection position of the sensor unit 6, and the sensor output rises (increases) from the L level to the H level as shown in FIG. 8(a). More specifically, when the roll R rotates 170 degrees in the reverse direction, the leading edge of the sheet 1 passes the contact position of the driven roller 10a of the separation flapper 10. The leading edge of the sheet 1 then leaves the contact position, begins to peel from the outer circumferential surface of the roll, and falls onto the arm member 4 due to its own weight and the return force of the bent sheet. At this time, as shown in FIG. 8(b), the sheet moves so that the outer surface of the leading edge of the sheet 1 gradually approaches the detection position of the sensor unit 6. When the roll R rotates another 200 degrees in the reverse direction, the outer surface of the leading edge of the sheet 1 passes the detection position above the sensor unit 6, as shown in FIG. 8(c). The strong reflected light from the outer surface of the sheet disappears, and only weak reflected light is received from the surface of the roll R, which is farther away. The sensor output then drops (decreases) from H level to L level. After that, when the roll R rotates further in the reverse direction by an angle θ, the leading edge of the sheet 1 reaches the contact position of the driven rotor 8.

[0035] The H level and L level are the two levels obtained by dividing the output intensity of the sensor unit 6. The H level occurs when the distance between the sensor unit 6 and the sheet 1 on the roll R is small, and the L level occurs when the distance is large. A threshold value TH, which serves as the boundary between these levels, is preset and stored in a nonvolatile memory in the printer or the sensor unit 6. The threshold value TH is set based on the sensor outputs L0 and H0. That is, the threshold value TH is set based on the intermediate value between the minimum and maximum levels of the sensor output when the roll R is rotated one or more times (e.g., multiple times). For example, if the minimum level sensor output is L0 and the maximum level sensor output is H0, the threshold value TH can be set as the intermediate value between these sensor outputs L0 and H0 (TH = (H0 + L0) / 2). Because the threshold value TH varies due to variations in the sensor unit 6, it is desirable to measure the sensor outputs L0 and H0 for each sensor unit 6 and set the threshold value TH based on the measured values.

[0036] As described above, the sensor output increases as the outer surface of the leading edge of the sheet peeled off from the roll R approaches the detection position of the sensor. The sensor output decreases as the outer surface of the leading edge of the sheet moves away from the sensor detection position. By having the CPU 201 capture this change in sensor output (predetermined change), it is possible to detect that the sheet 1 has been peeled off the roll R. As a result, it is possible to accurately determine the timing at which the sheet peeled off the roll reaches the guide surface and sheet peeling is complete. In the control for determining whether the leading edge of the sheet has been peeled off the roll R as described above, the sensor unit 6 and the CPU 201 correspond to the peel detection means in this invention.

[0037] As shown in FIG. 8(c), when the leading edge 1 of the sheet 1 passes the sensor unit 6, the sensor output changes from H level to L level. If the sensor output remains at L level for a certain period of time, the rotation of the roll R is stopped (steps S13 and S14). Specifically, after the sensor output changes from H level to L level, the roll R is further rotated in the reverse direction by a certain angle A. The system determines whether the sensor output remains at L level for a certain period of time. If this state continues, the rotation of the roll R is stopped. The certain angle A is an angle smaller than the angle θ, and in this example, it is half the angle θ (A=θ / 2). When the rotation of the roll R is stopped in step S14, the leading edge of the sheet 1 is positioned on the arm member 4 between the sensor unit 6 and the driven rotor 8. In this way, the position of the leading edge of the sheet can be obtained based on the detection result by the sensor unit 6. Therefore, by subsequently rotating the roll R in the direction of the arrow C1 (step S15), the leading edge of the sheet 1 can be automatically inserted into the sheet supply path between the arm member 4 and the separation flapper 10 and sent out (automatic loading).

[0038] If the sensor output does not change from H level to L level even after the roll R has rotated in the reverse direction one or more times (a predetermined amount of 360 degrees or more), the process proceeds from step S16 to step S17. Furthermore, if the sensor output does not remain at L level for a certain period of time even after the roll R has rotated in the reverse direction one or more times, the process proceeds from step S16 to step S17. If the leading edge of the sheet 1 does not separate from the outer surface of the roll R during one rotation of the roll R, it is considered that the sheet was not properly separated from the outer surface of the roll R. Furthermore, if the leading edge of the sheet 1 that separated from the outer surface of the roll R does not leave the sensor unit 6 during one rotation of the roll R, it is considered that the separated sheet has jammed on the sensor. In either case, automatic sheet feeding cannot be performed. In step S17, the rotation of the roll R is stopped, and the user is notified that automatic loading (automatic sheet feeding) could not be performed, and the user is prompted to manually insert the leading edge of the sheet 1 into the sheet feed path (manual sheet feeding). After inserting the leading edge of the sheet, the user instructs the device to feed the sheet. Based on this instruction, the roll R starts to rotate in the forward direction, and feeds the inserted sheet into the device.

[0039] As described above, in this embodiment, after the roll R is set, the leading edge of the sheet 1 can be automatically inserted into the sheet supply path and fed out. Therefore, after the roll R is set, the user does not need to manually insert the leading edge of the sheet 1 into the sheet supply path, which reduces the workload when setting the roll R.

[0040] (First embodiment) 9 to 11 are diagrams for explaining the first embodiment of the present invention.

[0041] In this embodiment, first, the change in the sensor output value (sub-data) for one revolution of the roll R obtained at a predetermined amplification factor is acquired for each of a plurality of sensor amplification factors, and suitable sub-data is selected from the plurality of sub-data and used for rotation control during sheet conveyance. In acquiring the plurality of sub-data, (1) the amplification factor is changed during one revolution of the roll to obtain the sensor output value, and some of the sensor output values ​​constituting the sub-data are acquired sporadically as actual measurement values. (2) The remaining sensor output values ​​constituting the sub-data are acquired by calculation or the like based on the sensor output values ​​acquired as actual measurement values. The sensor output values ​​thus obtained are From the force value, sub-data for one revolution of the roll for each individual amplification factor is obtained. (3) From the plurality of sub-data thus obtained, suitable sub-data is selected and used to determine the sensor amplification factor.

[0042] FIG. 9 is a flowchart showing the above-mentioned process (1) performed by the CPU 201 in order to obtain output values ​​when the roll R is rotated once at a plurality of sensor amplification factors.

[0043] First, the data processing area is initialized to secure an area for processing output data from the sensor unit 6 (step S81), and the current rotation angle of the roll R is set to 0 degrees (step S82). Next, the sensor gain is set to an initial value previously stored in the printer body or in nonvolatile memory within the sensor unit 6 (step S83). The output value amplified by the sensor gain is acquired and stored in the EEPROM 6g (step S84). The roll R is rotated a predetermined angle (step S85), and the sensor gain is increased (step S86). It is then determined whether the increased sensor gain has reached a predetermined upper limit (step S87). Steps S84 to S86 are repeated until the sensor gain reaches the upper limit, and multiple amplified output values ​​are acquired for each of the multiple gains. Note that the increase in the sensor gain may refer to an increase in either the light-emitting intensity of the light-emitting element 6c or the light-receiving sensitivity of the light-receiving element 6d, or both. Furthermore, the initial value of the sensor amplification factor (step S83), the degree to which the sensor amplification factor is increased (step S86), and the upper limit of the sensor amplification factor (step S87) may be set depending on the type of media used, the operating environment, and the like. When the sensor amplification factor reaches the upper limit, it is determined whether the angle of the roll R has rotated 360 degrees, i.e., whether the roll R has rotated once (step S88). Steps S83 to S87 are repeated until the angle of the roll R reaches 360 degrees. When the angle of the roll R reaches 360 degrees, it is determined that the output value for one rotation of the roll R has been acquired as data for determining the sensor amplification factor, and the process ends. In this way, by sequentially changing the sensor amplification factor during one rotation of the roll R (in the example of FIG. 11(a) , amplification factor 4 → amplification factor 3 → amplification factor 2 → amplification factor 1 → amplification factor 4 → amplification factor 3 . . . ), it is possible to acquire sensor output values ​​for one rotation at different rotation angles at multiple sensor amplification factors as data consisting of multiple sensor output values ​​for one rotation of the roll R.

[0044] Next, as the process (2) above, the remaining sensor output values ​​required to form the sub-data are obtained by calculation or the like based on the sensor output values ​​obtained in the flowchart of FIG.

[0045] FIG. 10 is a flowchart showing the above-mentioned process (3) performed by the CPU 201 to determine an appropriate sensor amplification factor based on the output value for each sensor amplification factor acquired according to the flowchart of FIG.

[0046] First, sub-data for determining the sensor amplification factor shown in FIG. 11(b) is created using the acquired multiple sensor output values, and the maximum value Hd and minimum value Ld of the amplified output values ​​corresponding to the initial sensor amplification factor are extracted from the sub-data (step S91). Next, it is determined whether the extracted maximum value Hd is smaller than an upper limit judgment value THmax, which is a first threshold (step S92). Next, it is determined whether the extracted minimum value Ld is larger than a lower limit judgment value THmin, which is a second threshold (step S93). Furthermore, it is determined whether the difference between the maximum value Hd and the minimum value Ld (Hd-Ld) is larger than a predetermined judgment value THa (step S94). If all judgments in steps S92 to S94 are appropriate, the sensor amplification factor is adopted as the amplification factor used to detect peeling of the leading edge of the sheet, and the appropriate sensor amplification factor determination process is terminated. If any one of the judgments from step S92 to step S94 is not satisfied, the sensor amplification factor is not adopted, and the maximum value Hd and minimum value Ld of the output value after amplification for the other sensor amplification factors are extracted (step S95), and the process is repeated. The process returns to step S92. If the determinations in steps S92 to S94 are not satisfied for all sensor amplification factors, an error message is displayed, such as an error message. In this way, the sensor amplification factor determination process is performed based on the maximum value Hd and minimum value Ld of the output values ​​after amplification for one rotation of the roll obtained according to the flowchart in Figure 9, and the amplification factor to be used for peeling detection at the leading edge of the sheet is determined. In other words, the process in Figures 9 and 10 described so far is the amplification factor adjustment operation for determining the sensor amplification factor to be used by the peeling detection means including the sensor unit 6 for peeling detection at the leading edge of the sheet.

[0047] FIG. 11(a) is a schematic diagram of an output waveform in which the amplified output values ​​obtained according to the flowchart of FIG. 9 are plotted for each rotation angle of the roll R. In this embodiment, the output waveform obtained from the sensor output values ​​corresponding to each of the multiple sensor amplification factors obtained according to the flowchart of FIG. 9 is used as sub-data for determining the sensor amplification factor in the flowchart of FIG. 10. Each output value plotted in FIG. 11(a) corresponds to part of that sub-data. In this diagram, the initial value of the sensor amplification factor is set to amplification factor 4, and the upper limit of the sensor amplification factor is set to amplification factor 1. Because the roll R is rotated each time a sensor output value is obtained, only one sensor output value is obtained for each rotation angle. Furthermore, even if the distance between the roll R and the sensor remains constant, the output value changes depending on the change in the sensor amplification factor.

[0048] FIG. 11(b) illustrates the positional relationship with the judgment value in the process performed in the flowchart of FIG. 10. In FIG. 11(b), the entire output waveform obtained by plotting the sensor output value for each rotation angle of the roll R is data consisting of sensor output values ​​acquired at different rotation angles while changing the sensor amplification factor while rotating the roll R once to determine the sensor amplification factor. The output waveforms corresponding to the multiple sensor amplification factors obtained by connecting the sensor output values ​​plotted for each amplification factor in FIG. 11(a) with lines correspond to the subdata corresponding to each of the multiple sensor amplification factors. For amplification factor 1 in FIG. 11(b), the maximum value Hd exceeds the upper limit judgment value THmax, so step S92 is not satisfied. For amplification factor 4, the minimum value Ld is below the lower limit judgment value THmin, so step S93 is not satisfied. For amplification factors 2 and 3, the maximum value Hd is smaller than the upper limit judgment value and the minimum value Ld is greater than the lower limit judgment value. Therefore, if the difference between the maximum and minimum values ​​(Hd - Ld) is greater than the judgment value THa, the sensor amplification factor is appropriate.

[0049] (Second embodiment) 12 and 13 are diagrams illustrating a second embodiment of the present invention. FIG. 12 is a block diagram of a control system in the second embodiment of the present invention. Similar to the first embodiment, the sensor unit 6 includes an optical sensor whose output changes depending on the distance between the sensor and the surface of the roll R. In this embodiment, similar to the first embodiment, an LED driver 6e with a dimming function under the control of the CPU 201 is connected to the LED light-emitting element 6c. The amplification factor of the light-emitting intensity of the light-emitting element 6c can be changed by adjusting the current flowing through the light-emitting element 6c. A current-voltage conversion circuit 6h and an amplifier circuit 6i are connected to the photodiode light-receiving element 6d. The amplification factor of the light-receiving sensitivity of the light-receiving element 6d can be changed by adjusting the resistance value of a digital potential meter 6f under the control of the CPU 201. The sensor unit 6 also includes a nonvolatile memory, EEPROM 6g, for storing the sensor amplification factors (the amplification factor of the light-emitting intensity of the light-emitting element 6c and the amplification factor of the light-receiving sensitivity of the light-receiving element 6d) after adjustment for the installed roll, the number of times the roll was installed, and other information.

[0050] FIG. 13 is an explanatory diagram of the output waveform of the sensor unit 6 when the roll R is rotated in the reverse direction C2. When the maximum value Hd of the sensor output of the sensor unit 6 becomes larger than the upper limit judgment value THmax, the sensor output may be saturated. When the minimum value Ld of the sensor output of the sensor unit 6 becomes smaller than the lower limit judgment value THmin, the sensitivity of the sensor unit 6 may be insufficient. Also, when the difference between the maximum value Hd and the minimum value Ld is less than a predetermined value, In this case, the sensor output may be affected by stationary noise, making it difficult to detect the position of the leading edge of the sheet 1. Therefore, a judgment value is also set to judge whether the difference between the maximum value Hd and the minimum value Ld is sufficient.

[0051] In this embodiment, in the initial stage of the sheet leading edge setting process (automatic loading) similar to the embodiment described above, the roll R is rotated in reverse, and the amplification factor of the sensor unit 6 is adjusted based on the output (sensor output) of the detection signal of the sensor unit 6 at that time.

[0052] FIG. 14 is a flowchart for explaining the amplification factor adjustment process 1 for adjusting the amplification factor of the sensor unit 6 (sensor amplification factor).

[0053] First, the CPU 201 initializes the data processing area to secure an area for processing output data from the sensor unit 6 (step S41), and then sets an initial value for the sensor gain (step S42). The sensor gain adjusted in the previous gain adjustment process is stored in the EEPROM 6g, and the stored gain is set as the initial value. If no gain is stored, a predetermined gain is set as the initial value. In this case, the initial gain may be set according to the type, diameter, width, etc. of the roll R input in advance via the operation panel 28. The diameter and width of the roll R may be set in the printing device itself, or may be set by a driver on a terminal such as a personal computer connected to the printing device by wire or wirelessly. Furthermore, a temperature and humidity sensor may be provided to set the initial gain according to the environmental temperature and humidity when the roll R is set.

[0054] Next, the CPU 201 rotates the roll R one or more times in the direction of arrow C2, acquires the sensor output at that time as an amplified output value by the sensor (step S43), and calculates a moving average value for each predetermined rotation angle of the roll R from the sensor output (step S44). In this embodiment, the sensor output for two rotations of the roll R is acquired as an amplified output value by the sensor, and calculates a moving average value for each predetermined rotation angle of the roll R. That is, in this embodiment, the entire sensor output for two rotations of the roll R is used as data for determining the above-mentioned sensor amplification factor, and sub-data corresponding to the sensor amplification factor is obtained from each sensor output. Then, using the moving average value calculated from this sub-data, the maximum value Hd and the minimum value Ld are extracted (step S45), and it is determined whether the maximum value Hd is equal to or greater than the upper limit judgment value THmax, which is the first threshold value in FIG. 13 (step S46). If the maximum value Hd is equal to or greater than the upper limit judgment value THmax, the CPU 201 determines whether the amplification factor of the light emission intensity of the light-emitting unit 6c is within a predetermined range (first allowable range) (step S47). If the amplification factor of the light-emitting intensity of the light-emitting unit 6c is within a predetermined range, the CPU 201 reduces the amplification factor of the light-receiving sensitivity of the light-receiving unit 6d (step S48), and if it is outside the predetermined range, the CPU 201 reduces the amplification factor of the light-emitting intensity of the light-emitting unit 6c (step S49). This makes it possible to avoid a situation in which the sensor output becomes saturated.

[0055] On the other hand, if the maximum value Hd is less than the upper limit judgment value THmax, the CPU 201 determines whether the minimum value Ld is less than the lower limit judgment value THmin, which is a second threshold (step S20). If the minimum value Ld is less than the lower limit judgment value THmin, the CPU 201 determines whether the amplification factor of the light-emitting intensity of the light-emitting unit 6c is within a predetermined range (step S51). If the amplification factor of the light-emitting intensity of the light-emitting unit 6c is within the predetermined range, the CPU 201 increases the amplification factor of the light-receiving sensitivity of the light-receiving unit 6d (step S52). If the amplification factor is outside the predetermined range, the CPU 201 increases the amplification factor of the light-emitting intensity of the light-emitting unit 6c (step S53). This increases the detection sensitivity of the sensor unit 6.

[0056] Furthermore, when the minimum value Ld is equal to or greater than the lower limit judgment value THmin, the CPU 201 It is determined whether the difference (Hd - Ld) between Hd and the minimum value Ld is less than a predetermined judgment value (step S51). If the difference (Hd - Ld) is less than the predetermined judgment value, the sensor output may be affected by stationary noise, making it difficult to detect the position of the leading edge of the sheet 1. In this case, the process proceeds from step S4 to step S51 in order to increase the amplification factor of the light emission intensity or light receiving sensitivity of the sensor unit 6. If the difference (Hd - Ld) is equal to or greater than the predetermined judgment value, it is determined that the light emission intensity and the amplification factor of the light receiving sensitivity of the sensor unit 6 have been appropriately adjusted, and the adjustment process of the amplification factor is terminated.

[0057] After adjusting the amplification factors of the light-emitting intensity or the light-receiving sensitivity in steps S48, S49, S52, and S53, the CPU 201 determines whether the amplification factors are within a predetermined range (step S55). That is, it determines whether the light-emitting intensity is within a predetermined range (first tolerance range) and whether the light-receiving sensitivity is within a predetermined range (second tolerance range). If the amplification factors of the light-emitting intensity and the light-receiving sensitivity are both within the predetermined range, the CPU 201 returns to step S41 to reconfirm whether the amplification factors are appropriate. If the amplification factors of the light-emitting intensity and the light-receiving sensitivity are not within the predetermined range, the CPU 201 determines that the amplification factors have exceeded the adjustment limit and executes error processing, such as outputting an error message. If the amplification factors of the light-emitting intensity and the light-receiving sensitivity are within the predetermined range, the CPU 201 may count the number of times the amplification factors are increased and decreased in steps S48, S49, S52, and S53, and execute error processing if the count value is equal to or greater than a certain number.

[0058] FIG. 15 is a flowchart for explaining the process of adjusting the amplification factor of the sensor unit 6 using the history of the number of times the roll has been installed and the sensor amplification factor in the initial stage of the leading end setting process (automatic loading).

[0059] FIG. 16 is a diagram illustrating the memory space used to store the number of roll installations and amplification factors in this embodiment. As shown in FIG. 2, the sheet supply device 200 in this embodiment is configured to allow different types of rolls R to be installed in two roll holding sections, the upper and lower sections. Therefore, to change the sheets supplied to the printing section depending on the application, it is possible to select which of the upper and lower roll holding sections to supply the sheets from, or to replace the roll R itself installed in the roll holding section. The nonvolatile memory (EEPROM 6g) serving as the storage means in FIG. 12 stores and memorizes the roll sheet name, which indicates the type of roll sheet, such as the material of the sheet 1, the sensor amplification factor set for each roll sheet, and the number of times the roll sheet has been installed in the roll holding section of the sheet supply device 200, as a set of history information. The nonvolatile memory (EEPROM 6g) also has separate memories for the upper and lower sections of the sheet supply device 200.

[0060] After the roll is replaced, first, the CPU 201 initializes the data processing area and reserves an area for processing the output data of the sensor unit 6 (step S200). After that, in order to check the sensor amplification factor set for the roll with the most number of roll installations among the history information stored in the EEPROM 6g, the CPU 201 sets a variable (N) representing the roll installation count ranking to 1 (step S201).

[0061] Next, it is checked whether the installation count of the roll with the most installation counts stored in the EEPROM 6g of the nonvolatile memory is zero (step S202). If the installation count is zero, it is determined that there is no history of the roll being installed, and amplification factor adjustment process 1 shown in FIG. 14 is performed to adjust the amplification factor of the sensor (step S204). If the installation count is not zero, it is determined that there is a history of the roll being installed, and it is further determined whether the installation count ranking variable (N) does not exceed a predetermined rank (step S203). If the installation count ranking variable does not exceed the predetermined rank, that is, if it is determined that the installation count of the roll for which the installation count ranking variable N is set to 1 is equal to or less than the predetermined number of times, the amplification factor of the stored installation count ranking is adjusted to the amplification factor of the sensor. The width ratio (adjusted amplification factor) is set (step S205). If the installation count ranking variable exceeds a predetermined rank, i.e., if it is determined that the installation count of the roll for which the installation count ranking variable N is set to 1 exceeds a predetermined number, it is determined that the state of the sheet forming the roll has changed due to repeated sheet supply from the roll, and that the sensor amplification factor stored in the EEPROM 6g does not correspond to the roll. Then, amplification factor adjustment process 1 shown in FIG. 14 is performed again to adjust the sensor amplification factor (step S204). Note that to determine whether the roll installation count is zero, when the roll is installed in the roll holding section, the user inputs information identifying the installed roll, such as the name of the roll sheet, from the operation panel 28, which is an input means. Then, since the roll sheet name and the sensor amplification factor stored in the EEPROM 6g are linked, if the roll is the same as a roll installed in the past, it is possible to determine whether the roll has a history of installation by comparing the roll sheet name with the corresponding sensor amplification factor. If the roll has never been installed before, the roll sheet name and the corresponding sensor amplification factor are not stored in the EEPROM 6g, so it can be determined that there is no history of the roll being installed.

[0062] If the amplification factor saved in the roll setting history is set as the adjusted amplification factor, the CPU 201 rotates the roll R twice in the direction of arrow C2 and acquires the sensor output at that time, i.e., the output value amplified by the sensor amplification factor (step S206). Then, a moving average is calculated from the sensor output for each predetermined rotation angle of the roll R (step S207). In this embodiment, the sensor output for two rotations of the roll R is acquired, and a moving average is calculated for each predetermined rotation angle of the roll R. The maximum value Hd and minimum value Ld of the moving average data are extracted, and the difference between the maximum value Hd and the minimum value Ld (Hd - Ld) is calculated (step S208).

[0063] If the maximum value Hd is smaller than the upper limit judgment value THmax which is a first threshold, the minimum value Ld is larger than the lower limit judgment value THmin which is a second threshold, and the difference between the maximum value Hd and the minimum value Ld (Hd-Ld) is equal to or larger than a predetermined judgment value, the CPU 201 determines that the adjusted amplification factor is an appropriate value, an appropriate amplification factor (steps S209 to S211).Then, the CPU 201 counts up the number of installations and updates the history (step S214).

[0064] On the other hand, if the maximum value Hd is equal to or greater than the upper limit judgment value THmax, the minimum value Ld is equal to or less than the lower limit judgment value THmin, and the difference between the maximum value Hd and the minimum value Ld (Hd-Ld) is less than the predetermined judgment value, it is determined that the amplification factor of the sensor is not an appropriate value (steps S209 to S211).

[0065] If it is determined that the amplification factor is not appropriate, amplification factor adjustment process 1 is performed to adjust the sensor amplification factor and determine the sensor amplification factor again (step S204), and the adjusted amplification factor and the number of roll installations are saved in EEPROM 6g (step S213). Then, it is confirmed whether the installation count ranking variable N has reached its upper limit, i.e., whether there are any rolls for which the sensor amplification factor needs to be checked (step S215). If N has reached its upper limit and there are no more rolls for which the sensor amplification factor needs to be checked, the sensor adjustment process ends. If N has not reached its upper limit and there are still rolls for which the amplification factor needs to be checked, the installation count ranking variable (N) is counted up to set the amplification factor of the roll sheet with the next highest number of installations (step S216).

[0066] Next, returning to step S202, for the roll sheet with the next highest number of installations, the stored roll installation history (FIG. 16) is checked to see if the installation count is zero (step S202) or if the variable (N) of the installation count ranking exceeds a predetermined rank (step S203). Then, the amplification factor stored in the installation count ranking is set (step S205), and the same steps as for the roll sheet with the highest number of installations are performed. First, the roll is rotated in the direction of arrow C2, and the sensor output is obtained as an output value amplified by the sensor amplification factor. Next, the maximum value Hd is checked to see if it is smaller than the upper limit judgment value THmax or if the minimum value Ld is larger than the lower limit judgment value THmin. It is then checked whether the difference (Hd-Ld) between the maximum value Hd and the minimum value Ld is equal to or greater than a predetermined judgment value (steps S206 to S211). If these conditions are met, the amplification factor for the current installation count ranking is judged to be an appropriate value, the installation count is counted up, and the history is updated (step S214). If the maximum value Hd is equal to or greater than the upper limit judgment value THmax, the minimum value is equal to or less than the lower limit judgment value THmin, or the difference (Hd-Ld) between the maximum value Hd and the minimum value Ld is less than the predetermined judgment value, the amplification factor of the sensor is adjusted in sensor amplification factor adjustment process 1 (step S204).

[0067] In this way, the sensor amplification factor stored in the EEPROM 6g is checked sequentially for each roll. Then, in steps S209 to S211, if it is determined that the sensor amplification factor is an appropriate value, the installation count for the installation count ranking (N) at that time is counted up, and the roll installation history in FIG. 201 is updated (step S214). Then, the above-described amplification factor adjustment process and determination process are repeated until the installation count ranking variable (N) reaches its upper limit, that is, until there are no more rolls for which the sensor amplification factor needs to be checked.

[0068] In the sensor amplification factor adjustment process 1 (step S204), which is performed when the number of roll installations is zero, when the installation count rank exceeds a predetermined rank, or when it is determined that the sensor amplification factor set for the roll is not an appropriate value, when adjustment of the sensor amplification factor is completed, it is determined whether the amplification factor value is equivalent to the amplification factor value stored in the memory space of the roll installation history, and if present, the installation count is counted up, and if not present, the installation count is set to 1, the roll installation history is updated, and stored in the EEPROM 6g of the nonvolatile memory (step S213). In addition, the sensor amplification factor adjustment process and the determination process of whether the sensor amplification factor is an appropriate value in this embodiment may be the same as the amplification factor adjustment process and the determination process in the first embodiment.

[0069] The predetermined order in which the roll installation history is used in step S203 can be changed on the operation panel 28. As a result, sensor adjustment after a roll sheet replacement starts with the sensor amplification factor value of the roll sheet that has been installed the most frequently as the initial value, and adjustment is performed in the order of roll sheets that have been installed the most frequently until the acquired sensor output matches the predetermined waveform. Then, the sensor adjustment is repeated while changing the saved sensor amplification factor value. The adjusted sensor amplification factor value is stored in the EEPROM 6g for each roll, and when a sheet is fed, the sensor amplification factor corresponding to that roll is read from the EEPROM 6g and the sensor is adjusted, thereby shortening the time required for sensor adjustment. [Explanation of symbols]

[0070] 1...sheet, 6...sensor unit (sensor), 6c...light emitting section, 6d...light receiving section, 200...sheet supply device, 33...motor, R...roll

Claims

1. a driving means for rotating the roll formed by winding the sheet in a first direction in which the sheet is sent out to the conveyance path and in a second direction opposite to the first direction; a sensor that outputs an output value according to the distance between a detection position facing the circumferential surface of the roll and the circumferential surface of the roll; Equipped with a sheet feeding device that determines an amplification factor of the sensor based on data consisting of a plurality of output values ​​acquired at different rotation angles while rotating the roll in the second direction by the driving means, The sheet feeding device according to claim 1, wherein the data is acquired by changing the amplification factor in a plurality of steps during one rotation of the roll.

2. the data includes a plurality of sub-data obtained from the output values ​​corresponding to the plurality of amplification factors changed during one rotation of the roll, 2. The sheet feeding device according to claim 1, wherein the amplification factor is determined based on the plurality of sub-data.

3. 3. The sheet feeding device according to claim 2, wherein the amplification factor is determined based on a maximum value and a minimum value corresponding to each of the plurality of sub-data.

4. 3. The sheet feeding device according to claim 2, wherein the data is data obtained when the roll is rotated at least two times for each of a plurality of the amplification factors.

5. 5. The sheet feeding device according to claim 4, wherein a moving average value of the sub-data is obtained for each of the plurality of amplification factors, and the amplification factor is determined based on a maximum value and a minimum value of the moving average value.

6. A sheet feeding device as described in claim 3 or 5, characterized in that the amplification factor is an amplification factor among the multiple amplification factors whose maximum value is smaller than a first threshold value, whose minimum value is greater than a second threshold value that is smaller than the first threshold value, and whose difference between the maximum value and the minimum value is greater than a predetermined judgment value.

7. the sensor is an optical sensor having a light-emitting unit and a light-receiving unit, 7. The sheet supply device according to claim 1, wherein the amplification factor is an amplification factor that changes at least one of the light emission intensity of the light emitting portion and the light receiving sensitivity of the light receiving portion. Feeding device.

8. It is configured so that different rolls can be replaced and installed. an input means for inputting information identifying a roll installed in the device; a storage means for storing history information including the amplification factor and the number of times the roll has been installed for each roll; 8. The sheet feeding device according to claim 1, further comprising:

9. The sheet feeding device according to claim 8, characterized in that when the number of times the roll installed in the device is zero, and when the number of times the roll installed in the device is more than a predetermined number, the amplification factor is determined based on the data, and the determined amplification factor is stored in the memory means.

10. When the number of times the roll has been installed in the device is equal to or less than a predetermined number of times and the storage means stores the amplification factor, the amplification factor stored in the storage means is an appropriate amplification factor.

10. The sheet feeding device according to claim 8, wherein the amplification factor is determined based on the data, and if it is not an appropriate amplification factor, the amplification factor is determined again based on the data, and the determined amplification factor is stored in the memory means.

11. a sheet feeding device according to any one of claims 1 to 10; a printing unit that prints an image on a sheet supplied from the sheet supply device; A printing device comprising:

Images