JP7314205B2 - Sheet feeding device and printing device - Google Patents

Description

The present invention relates to a sheet feeding device and a printing device that pull out and feed a sheet from a roll on which a continuous sheet is wound.

Japanese Patent Application Laid-Open No. 2002-200002 discloses a printing apparatus capable of automatically feeding a sheet by detecting the leading edge of the sheet of the mounted roll. In this device, the roll is rotated in the winding direction opposite to the supply direction, and an optical sensor arranged near the roll detects that the leading edge of the sheet is separated from the roll by its own weight.

JP 2011-37557 A

The optical sensor of Patent Document 1 detects sheet peeling by obtaining an ON output from reflected light at the moment when the leading edge of the sheet peeled from the roll passes through the sensor optical axis parallel to the tangential line of the roll. The signal intensity of the sensor output at this time is almost zero until the leading edge of the peeled sheet reaches the optical axis of the sensor, and at the moment when the leading edge of the sheet passes the optical axis of the sensor, a pulse signal is generated by the reflected light from the edge of the leading edge of the sheet. After passing through the sensor optical axis, the sensor light hits the inner surface of the peeled sheet, but since the sensor optical axis and the inner surface of the sheet are almost parallel and the distance increases rapidly, the reflection intensity is weak and the signal level after passing sharply drops. In other words, the optical sensor disclosed in the patent document can basically determine only the moment when the leading edge of the sheet passes the sensor optical axis during the peeling process.

However, in an actual device, the peeling speed (the speed at which the leading edge of the sheet moves) changes depending on various conditions such as the rigidity of the sheet used (returning force that causes the bent sheet to return to its original state) and static electricity. Therefore, in a configuration in which the leading edge of the sheet is detected by a momentary signal pulse during peeling as in Patent Document 1, the signal pulse generation timing changes depending on the situation, and it may be difficult to detect sheet peeling with high accuracy. This timing deviation may hinder the subsequent sheet feeding operation. Patent Document 1 does not disclose any means for solving such problems.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a sheet feeding device and a printing device that can accurately detect sheet separation from a roll and automatically feed the sheet.

The sheet feeding apparatus of the present invention includes a holding section that rotatably holds a rotating shaft of a roll formed by winding a sheet at a fixed position, a first direction for sending out the sheet from the roll held by the holding section, and a driving means that rotationally drives the rotating shaft to rotate the roll in a second direction opposite to the first direction, and a roll.inA sheet feeding device, comprising detecting means for detecting a leading edge of a sheet, a first contact member in contact with a roll, and a second contact member in contact with the roll, for feeding a sheet in an area upstream of the first contact member and downstream of the second contact member in the second direction of the roll, wherein after the leading edge of the sheet is detected based on an output from the detecting means by rotating the roll in the second direction by the driving means, the leading edge of the sheet passes through the second contact member and reaches the area. Rotating the roll in the second direction by the driving means based on the angle of the rotating shaftBythe tip of the sheetfrom outside said areaThe rotation of the roll is changed from the second direction to the first direction when reaching the region.

According to the present invention, it is possible to accurately detect sheet separation from the roll and perform automatic feeding.

1 is a perspective view of a printing device according to an embodiment of the invention; FIG. 4 is an explanatory diagram of a sheet conveying path in the printing apparatus; FIG. FIG. 3 is an explanatory diagram of a sheet feeding device; FIG. 4 is an explanatory diagram of a sheet feeding device when the outer diameter of a roll is small; 3 is a block diagram for explaining a control system of the printing device; FIG. 7 is a flowchart of sheet supply preparation processing; FIG. 4 is an explanatory diagram of a sensor unit according to the first embodiment of the present invention; 9 is a flowchart for explaining sheet leading edge setting processing; FIG. 10 is an explanatory diagram of changes in the sensor output of the sensor unit according to the second embodiment of the present invention; FIG. 4 is an explanatory diagram of sensor output of the sensor unit; 9 is a flowchart for explaining sheet leading edge setting processing; FIG. 11 is a block diagram of a control system of a printing device according to a third embodiment of the invention; FIG. 4 is an explanatory diagram of sensor output of the sensor unit; 5 is a flowchart for explaining a sensor amplification factor adjustment process; FIG. 11 is an explanatory diagram of deployment positions of sensor units according to the fourth embodiment of the present invention; FIG. 4 is an explanatory diagram of the relationship between the optical axis of the sensor unit and the outer peripheral surface of the roll; FIG. 4 is an explanatory diagram of the configuration of the sensor unit; FIG. 11 is an explanatory diagram of deployment positions of sensor units according to the fifth embodiment of the present invention; FIG. 11 is an explanatory diagram of sensor outputs of a sensor unit according to a sixth embodiment of the present invention; FIG. 4 is an explanatory diagram of the behavior of the leading edge of the sheet; 9 is a flowchart for explaining sheet leading edge setting processing; FIG. 20 is an explanatory diagram of a stop position of the leading edge of a sheet according to the seventh embodiment of the present invention; 9 is a flowchart for explaining sheet leading edge setting processing; FIG. 7 is an explanatory diagram of another configuration example of the sheet feeding device;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. First, the basic configuration of the present invention will be explained.

<Basic configuration>
1 to 5 are explanatory diagrams of the basic configuration of a printing apparatus as an embodiment of the present invention. The printing apparatus of this example is an inkjet printing apparatus including a sheet feeding device for feeding sheets as print media and a printing section for printing images on the sheets. For the sake of explanation, coordinate axes are set as shown in the drawing. 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.

As shown in FIG. 1, in the printing apparatus 100 of this example, a roll R (roll sheet) obtained by winding a sheet 1, which is a long continuous sheet (sometimes referred to as a web), into a roll can be set in two roll holding units, upper and lower. Images are printed on the sheets 1 selectively pulled out from those rolls R. The user can use various switches provided on the operation panel 28 to input various commands to the printer 100, such as designating the size of the sheet 1 and switching between online/offline.

FIG. 2 is a schematic cross-sectional view of a main part of the printing device 100. As shown in FIG. Two feeding devices 200 corresponding to two rolls R are arranged one above the other. The sheet 1 pulled out from the roll R by the feeding device 200 is conveyed by the sheet conveying section (conveying mechanism) 300 along the sheet conveying path to the printing section 400 capable of printing an image. The printing unit 400 prints an image on the sheet 1 by ejecting ink from the inkjet print head 18 . The print head 18 uses ejection energy generating elements such as electrothermal conversion elements (heaters) and piezo elements to eject ink from ejection openings. The print head 18 is not limited to the ink jet system, nor is the printing system of the print unit 400 limited. For example, it may be a serial scan system or a full line system. In the case of the serial scan method, an image is printed by conveying the sheet 1 and scanning the print head 18 in a direction crossing the conveying direction of the sheet 1 . In the case of the full-line system, an elongated print head 18 extending in a direction intersecting the conveying direction of the sheet 1 is used to print an image while continuously conveying the sheet 1 .

The roll R, with the spool member 2 inserted into its hollow hole, is set in the roll holding portion of the supply device 200, and the spool member 2 is driven forward and reverse by a roll driving motor 33 (see FIG. 5). As will be described later, the supply device 200 includes a drive section 3, an arm member (moving body) 4, an arm rotating shaft 5, a sensor unit 6, a swinging member 7, driven rotating bodies (contact bodies) 8 and 9, a separation flapper (upper guide body) 10, and a flapper rotating shaft 11.

The conveying guide 12 guides the front and back surfaces of the sheet 1 pulled out from the feeding device 200 and guides the sheet 1 to the printing section 400 . The conveying roller 14 is rotated forward and backward in directions of arrows D1 and D2 by a motor 35 (see FIG. 5) for driving the conveying roller, which will be described later. The nip roller 15 can be driven to rotate according to the rotation of the conveying roller 14, and can come into contact with and separate from the conveying roller 14 and can adjust the nip force by a nip force adjusting motor 37 (see FIG. 5). 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, thereby applying back tension to the sheet 1 and conveying it in a stretched state.

The platen 17 of the printing section 400 regulates the position of the sheet 1, and the cutter 20 cuts the sheet 1 on which the image is printed. The cover 42 of the roll R prevents the image-printed sheet 1 from returning to the supply device 200 . Such operations in the printing apparatus 100 are controlled by a CPU 201 (see FIG. 5), which will be described later. The platen 17 is a platen having a negative pressure or electrostatic force adsorption means, and can adsorb the sheet onto the platen to stably support the sheet.

FIG. 3 is an explanatory diagram of the supply device 200, and the roll R in FIG. 3(a) is in a state where its outer diameter is relatively large. An arm member (moving body) 4 is attached to the transport guide 12 by an arm rotating 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 lower surface of the sheet 1 pulled out from the roll R is formed on the upper portion of the arm member 4. As shown in FIG. A torsion coil spring 3c is interposed between the arm member 4 and the rotating cam 3a of the drive unit 3 to press the arm member 4 in the direction of the arrow A1. The rotary cam 3a is rotated by a pressing force adjusting motor 34 (see FIG. 5), 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 its rotational position. When the leading edge of the sheet 1 (part of the sheet 1 including the leading edge) is set in the sheet supply path through between the arm member 4 and the separation flapper 10, the pressing force of the torsion coil spring 3c on the arm member 4 is switched in three steps according to the rotational position of the rotary cam 3a. That is, the pressing state is switched between a pressing state with a relatively small force (weak nip pressing force), a pressing state with a relatively large force (strong nip pressing force), and a pressing force released state.

A swinging member 7 is swingably attached to the arm member 4, and first and second driven rotating bodies (rotating bodies) 8 and 9 are rotatably attached to the swinging member 7 so as to be displaced in the circumferential direction of the roll R. These driven rotating bodies 8 and 9 move according to the outer shape of the roll R, and press the outer peripheral portion of the roll R from below in the gravity direction by pressing force in the direction of arrow A1 against the arm member 4 . That is, the driven rotating bodies 8 and 9 are pressed against the outer peripheral portion of the roll R from below the horizontal central axis of the roll R in the direction of gravity. The pressing force is changed according to the pressing force that presses the arm member 4 in the arrow A1 direction.

A plurality of arm members 4 each having a swing member 7 are provided so as to have 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 retaining portion 7b, by which the rotating shaft 4a of the arm member 4 is received with a predetermined play.

The bearing portion 7a is provided at the center of gravity of the swinging member 7, and is supported by the rotating shaft 4a so that the swinging member 7 has a stable posture in each of the X-axis direction, the Y-axis direction, and the Z-axis direction. Further, since the rotating shaft 4a is received with play, the swinging 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 the arrow A1 against the arm member 4. Such a configuration (equalization mechanism) allows a change in the pressure contact posture of the first and second driven rotating bodies 8 and 9 with respect to the outer peripheral portion of the roll R. FIG. As a result, the contact areas between the sheet 1 and the first and second driven rotating bodies 8 and 9 are always kept maximized, and the pressing force against the sheet 1 is made uniform, so that the variation in the conveying force of the sheet 1 can be suppressed. Since the driven rotating bodies 8 and 9 are pressed against the outer peripheral portion of the roll R, the occurrence of slack in the sheet 1 is suppressed and the conveying force is increased.

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 about a flapper rotation 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. If it is necessary to press the roll R more strongly, the biasing force of a biasing member such as a spring may be used. A driven roller 10 a is rotatably provided at the portion of the separation flapper 10 that contacts the roll R 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 to the surface of the roll R as possible so that the tip of the sheet can be easily separated from the roll R.

The sheet 1 is pulled out from the roll R by passing above the driven rotating bodies 8 and 9, the lower surface thereof is guided by the upper guide part 4b of the arm member 4, and then supplied through a supply path formed between the separation flapper 10 and the arm member 4. - 特許庁In this manner, the driven rotors 8 and 9 are pressed against the outer peripheral portion of the roll R from below, and the guide portion 4b guides the lower surface of the sheet 1 pulled out over the driven rotors 8 and 9. As shown in FIG. As a result, the sheet 1 can be smoothly fed by utilizing the weight of the sheet 1 itself. Further, the driven rotating bodies 8 and 9 and the guide portion 4b move according to the outer diameter of the roll R, so that the sheet 1 can be reliably pulled out from the roll R and conveyed regardless of the outer diameter of the roll R.

One of the features of the apparatus of this embodiment is the automatic sheet loading function (automatic paper feeding function). In automatic loading, when the 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 time of sheet feeding (when feeding) (referred to as the reverse direction or the second direction, the direction of arrow C2 in FIG. 3(a)). Next, the apparatus rotates the roll R in the direction of rotation when the sheet is supplied (referred to as the forward direction or the first direction, the direction of the arrow C1 in FIG. 3A), and automatically feeds the leading edge of the sheet separated from the roll R. The sensor unit 6 is a unit that includes a leading edge detection sensor that detects that the leading edge of the sheet 1 has peeled off from the outer peripheral surface of the roll R and that the sheet has been peeled (separated from the sheet). The leading edge of the sheet 1 detected by the sensor unit 6 is automatically inserted into the sheet supply path between the arm member 4 and the separation flapper 10 and sent out. A more detailed procedure for this automatic loading function will be described later.

In addition, the printing apparatus 100 of this example includes two upper and lower supply devices 200, and can switch from a state in which the sheet 1 is supplied from one supply device 200 to a state in which the sheet 1 is supplied from the other supply device 200. In such a case, one supply device 200 rewinds the sheet 1 that has been supplied up to that time onto the roll R. As shown in FIG. The leading edge of the sheet 1 is retracted to a position where it is detected by the sensor unit 6 or another sheet edge sensor provided near the sensor unit 6 .

FIG. 4 is an explanatory diagram of the supply device 200 when the outer diameter of the roll R is relatively small. Since the arm member 4 is always pressed in the direction of the arrow A1 by the torsion coil spring 3c, it rotates in the direction of the arrow A1 as the outer diameter of the roll R decreases. Further, by rotating the rotating cam 3a according to the change in the outer diameter of the roll R, the pressing force of the torsion coil spring 3c on the arm member 4 can be maintained within a predetermined range regardless of the change in the outer diameter of the roll R. Further, since the separation flapper 10 is also always pressed in the direction of the arrow B1, it rotates in the direction of the arrow B1 as the outer diameter of the roll R decreases. As a result, the separation flapper 10 forms a supply path with the conveying 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, the arm member 4 and the separation flapper 10 rotate according to the change in the outer diameter of the roll R, thereby forming a supply path of substantially constant size between them regardless of the outer diameter of the roll R.

FIG. 5 is a block diagram for explaining a configuration example of a control system in the printing apparatus 100. As shown in FIG. The CPU 201 of the printing device 100 controls each section of the printing device 100 including the feeding device 200 , the sheet conveying section 300 and the printing section 400 according to the control program stored in the ROM 204 . The type and width of the sheet 1, various setting information, and the like are input to the CPU 201 from the operation panel 28 via the input/output interface 202. FIG. The CPU 201 is also connected to various external devices 29 including a host device such as a personal computer via an external interface 205 and exchanges various information such as print data with the external device 29 . The CPU 201 also writes and reads information about the sheet 1 to and from the RAM 203 . The motor 33 is a roll driving motor for rotating the roll R forward and reverse through the spool member 2, and constitutes a driving mechanism (rotating mechanism) capable of driving the roll R to rotate. The pressing force adjusting 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 driving motor 35 is a motor that rotates the transport 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 on the supply device 200 . The roll rotation amount sensor 36 is a sensor (rotation angle detection sensor) for detecting the amount of rotation of the spool member 2, that is, the roll R, and is, for example, a rotary encoder that outputs a number of pulses corresponding to the amount of rotation of the roll R.

<Sheet supply preparation processing>
FIG. 6 is a flow chart for explaining the supply preparation process for the sheet 1 starting from setting of the roll R. As shown in FIG.

The CPU 201 of the printing apparatus 100 waits in a state (weak nip state) in which the arm member 4 is pressed in the direction of the arrow A1 with a "weak nip pressing force", and first determines whether or not the roll R is 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 is set. After the roll R is set, the CPU 201 switches the arm member 4 to a state (strong nip state) in which the arm member 4 is pressed in the direction of the arrow A1 by the "strong nip pressing force" (step S2). Next, the CPU 201 executes sheet leading edge setting processing for setting the leading edge of the sheet 1 in the sheet supply path through 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 set (inserted) into the sheet supply path. Details of the sheet leading edge setting process will be described later.

After that, the CPU 201 causes the roll driving motor 33 to rotate the roll R in the direction of the arrow C1 to start feeding 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 conveying roller 14 forward in the direction of 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 releases the pressing force pressing the arm member 4 in the direction of the arrow A1 to separate the first and second driven rotating bodies 8 and 9 from the roll R (nip release state) (step S7).

After that, the CPU 201 determines whether or not the sheet is conveyed (skewed) in the sheet conveying portion 300 while being inclined. Specifically, the sheet 1 is conveyed by a predetermined amount in the sheet conveying portion 300, and the amount of skew that occurs at that time is detected by a carriage on which the print head 18 is mounted or a sensor provided in the sheet conveying portion 300. FIG. If the amount of skew is larger than a predetermined allowable amount, feeding and backfeeding of the sheet 1 are repeated by forward and reverse rotation of the conveying roller 14 and the roll R while applying back tension to the sheet 1 . Such an operation corrects the skew of the sheet 1 (step S8). In this way, when the skew feeding of the sheet 1 is corrected and when an image is printed on the sheet 1, the feed device 200 is placed in the nip release state, thereby avoiding the influence of the driven rotating members 8 and 9 on the skew correction accuracy of the sheet 1 and the image printing accuracy. After that, the CPU 201 causes the sheet conveying section 300 to move the leading edge of the sheet 1 to a waiting position (home position) before starting printing in the printing section 400 (step S9). Thus, the preparation for supplying the sheet 1 is completed. After that, the sheet 1 is pulled out from the roll R as the roll R rotates, and is conveyed to the printing section 400 by the sheet conveying section 300 .

Sheet leading edge setting processing (step S20) in FIG. 5 in such a basic configuration of the printing apparatus 100 will be described below as an embodiment of the present invention.

(First embodiment)
In this embodiment, as the sensor unit 6, an optical sensor whose output changes according to the facing distance from the front surface (outer surface) of the sheet 1 is used. Then, based on the change in the output of the sensor unit 6 during the rotation of the roll R in the reverse direction (arrow C2 direction), after detecting that the leading end of the sheet 1 has been peeled off and separated from the outer peripheral surface of the roll R, the roll R is rotated in the forward direction of the arrow C1 to supply the sheet 1.

As shown in FIG. 7, the sensor unit 6 of this example incorporates a light-emitting portion 6c such as an LED and a light-receiving portion 6d such as a photodiode. The light emitted from the light-emitting portion 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 portion 6d. The light emitted from the light-emitting portion 6c and detected by the light-receiving portion 6d includes specularly reflected light reflected from the surface of the sheet 1 on the roll R. As shown in FIG. The output value of the light receiving portion 6b changes according to the facing distance between the sensor unit 6 and the downward surface of the sheet 1 (the outer surface of the sheet which was the outer peripheral surface of the roll and is printed by the printing portion). That is, the smaller the distance (gap) between the sensor unit 6 and the surface of the sheet 1, the larger the output value of the light receiving portion 6b, and the larger the distance (gap), the smaller the output value. The sensor unit 6 may have a configuration in which the output value of the detection signal changes according to the distance between the sensor unit 6 and the surface of the sheet 1, and the light-emitting portion 6c and the light-receiving portion 6d are not limited to LEDs and photodiodes. Moreover, the light detected by the light receiving section 6d is not limited to specularly reflected light. The sensor unit 6 is connected to the CPU 201 (see FIG. 5), and the CPU 201 acquires the detection result of the sensor unit 6 at arbitrary timing.

8 and 9 are explanatory diagrams of the sheet leading edge setting process (step S3 in FIG. 6) using the sensor unit 6. FIG. As described above, the sheet leading edge setting process (automatic loading) is a process of automatically inserting the leading edge of the sheet 1 on the roll R into the sheet supply path between the arm member 4 and the separation flapper 10 after the roll R is set, and feeding the sheet. The arm member 4 faces the front surface of the sheet 1 (outer surface of the sheet), and the separation flapper 10 faces the back surface of the sheet 1 (inner surface of the sheet).

Before starting the sheet leading edge setting process, the CPU 201 first determines whether or not the roll R is set (step S1 in FIG. 6). In this example, when the roll sensor 32 detects the spool member 2 of the roll R, it is determined that the roll R is set. After the roll R is set, the CPU 201 switches the arm member 4 to a state (strong nip state) in which the arm member 4 is pressed in the direction of the arrow A1 by the "strong nip pressing force" (step S2 in FIG. 6).

In the subsequent sheet leading edge setting process (step S3 in FIG. 6), the CPU 201 first rotates the roll R in the opposite direction of the arrow C2 (reverse rotation) (step S11). Then, during the reverse rotation of the roll R, it is determined whether or not the output of the detection signal (sensor signal level) of the sensor unit 6 has changed from within the H level range (within the first level range) to within the L level range (within the second level range) (step S12).

FIG. 9A is an explanatory diagram of an example of the waveform of the sensor output, and assumes that the rotation angle of the roll R at the start of reverse rotation of the roll R is 0 degrees. Normally, the sensor output is at L level. When the roll R rotates in reverse by 170 degrees, the sensor output rises (increases) from the L level to the H level as shown in FIG.

More specifically, when the roll R is reversely rotated by 170 degrees, the leading edge of the sheet 1 passes through the contact position of the driven roller 10a of the separation flapper 10. As shown in FIG. As a result, the leading edge of the sheet 1 moves out of the abutting position, starts peeling from the outer peripheral 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. 9B, the sheet moves such that the outer surface of the leading edge of the sheet 1 gradually approaches the detection position of the sensor unit 6 . Further, when the roll R rotates reversely by 200 degrees, the sheet outer surface of the leading edge of the sheet 1 passes the detection position above the sensor unit 6 as shown in FIG. 9(c). Then, the strong reflected light from the outer surface of the sheet disappears, and the weak reflected light from the surface of the roll R which is far away is received, and the sensor output rapidly drops (decreases) from the H level to the L level. After that, when the roll R is further reversely rotated by the angle θ, the leading edge of the sheet 1 reaches the contact position of the driven rotating body 8 . The H level and the L level are obtained by dividing the output intensity of the sensor unit 6 into two levels, and the H level is set when the facing interval between the sensor unit 6 and the sheet 1 of the roll R is small, and the L level is set when the interval is large. A threshold TH as a boundary dividing these levels is set in advance and stored in a non-volatile memory inside the printer main body or the sensor unit 6 . The threshold TH is set based on the sensor outputs L0, H0. That is, it is set on the basis of an intermediate value between the minimum level and the maximum level of the sensor output when the roll R is rotated one or more times (for example, multiple times). For example, when the sensor output at the minimum level is L0 and the sensor output at the maximum level is H0, the threshold TH can be set as an intermediate value (TH=(H0+L0)/2) between these sensor outputs L0 and H0. Since the threshold TH fluctuates due to variations in the sensor units 6, it is desirable to measure the sensor outputs L0 and H0 for each individual sensor unit 6 and set the threshold TH based on the measured values.

As described above, the sensor output increases as the outer surface of the sheet separated from the roll R approaches the detection position of the sensor. Then, the sensor output drops corresponding to the movement of the outer surface of the sheet away from the detection position of the sensor due to the subsequent rotation of the roll in the second direction. By capturing such a change in sensor output (predetermined change), it is possible to accurately obtain the timing at which the sheet peeled from the roll reaches the guide surface and the sheet peeling is completed.

As shown in FIG. 9B, when the leading edge 1 of the sheet 1 passes the sensor unit 6, the sensor output changes from H level to L level, and thereafter, when the L level of the sensor output continues 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, it is determined whether or not the sensor output continues to be at L level in a fixed period in which the roll R is reversely rotated by a fixed angle A, and when it continues, the rotation of the roll R is stopped. The constant angle A is an angle smaller than the angle θ, and in this example, 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 rotating member 8. As shown in FIG. Therefore, by rotating the roll R forward 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 (automatic loading).

If the sensor output does not change from the H level to the L level even when the roll R rotates in the opposite direction by one turn or more (a predetermined amount of 360 degrees or more), the process proceeds from step S16 to step S17. Further, if the sensor output does not remain at the L level for a certain period of time even when the roll R rotates backward by a predetermined amount equal to or more than one turn, the process proceeds from step S16 to step S17. If the leading end of the sheet 1 is not separated from the outer peripheral surface of the roll R during one rotation of the roll R, it is considered that the separation from the outer peripheral surface of the roll R is defective. If the leading edge of the sheet 1 separated from the outer peripheral 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 causes a paper jam on the sensor. In either case, automatic paper feeding cannot be performed. In step S17, the rotation of the roll R is stopped, the user is notified that automatic loading (automatic paper feeding) could not be executed, and the user is urged to perform a manual operation (manual paper feeding) for inserting the leading edge of the sheet 1 into the sheet feeding path. After inserting the leading edge of the sheet, the user instructs the apparatus to feed the sheet. Based on this instruction, the roll R starts to rotate in the forward direction to send out the inserted sheet into the apparatus. 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 sent out. Therefore, the user does not have to manually insert the leading edge of the sheet 1 into the sheet supply path after setting the roll R, and the work load when setting the roll R is reduced.

(Second embodiment)
10 and 11 are explanatory diagrams of the second embodiment of the present invention. The output of the sensor unit 6 changes according to the facing distance from the surface of the sheet 1, as in the above-described embodiment. For example, in the case of a sheet 1 with a large crest amount and a sheet 1 with high rigidity, when the roll R is reversely rotated in the direction of arrow C2, the sensor output may change during the period from when the leading edge 1 of the sheet 1 passes through the driven rotor 9 until it passes through the driven roller 10a. That is, during that period, the output of the sensor unit 6 may temporarily rise from the L level to the H level and then return to the L level.

FIG. 10 is an explanatory diagram of the output waveform of the sensor unit 6 and the behavior of the leading edge of the sheet 1 when the roll R of the sheet 1 with a large amount of crest is rotated in reverse. From the state where the leading end of the sheet 1 is near the driven roller 10a, the roll R starts to reversely rotate in the direction of the arrow C2, and when it rotates about 45 degrees from the rotation start position, the leading end 1 of the sheet 1 passes through the driven roller 10a and falls onto the arm member 4, as shown in FIG. As a result, as shown in FIG. 10A, the output of the sensor unit 6 rises from the L level to the H level when the rotation angle of the roll R is around 45 degrees. After that, when the roll R rotates about 90 degrees from the rotation start position, the leading edge 1 of the sheet 1 passes over the sensor unit 6 as shown in FIG. 9C. As a result, as shown in FIG. 10(a), the output of the sensor unit 6 drops from the H level to the L level when the rotation angle of the roll R is around 90 degrees.

Furthermore, when the roll R continues to rotate in the reverse direction and rotates about 270 degrees from the rotation start position, the leading end of the sheet 1 is positioned above the roll R, and the weight of the leading end 1 causes the sheet 1 to bend as shown in FIG. 10(b). When such bending occurs, the seat outer surface of the seat 1 approaches the sensor unit 6 as shown in FIG. 10(b). As a result, as shown in FIG. 10A, the output of the sensor unit 6 rises from the L level to the H level when the rotation angle of the roll R is around 270 degrees. After that, by further rotating the roll R in the reverse direction, the bent portion of the sheet 1 is wound around the roll R and the sheet 1 is separated from the sensor unit 6, as shown in FIG. 10(c). As a result, as shown in FIG. 10(a), the output of the sensor unit 6 returns from the H level to the L level when the roll R rotates at about 350 degrees.

When the reverse rotation of the roll R is continued, such changes in the output of the sensor unit 6 are repeated. In the present embodiment, even when the sensor output changes in this way, the position of the leading edge of the sheet 1 can be identified, and the leading edge can be automatically inserted into the sheet supply path between the arm member 4 and the separation flapper 10 to feed the sheet (sheet leading edge setting process).

FIG. 11 is a flowchart for explaining sheet leading edge setting processing (automatic loading) in this embodiment.

Before starting the sheet leading edge setting process, the CPU 201 first determines whether or not the roll R is set (step S1 in FIG. 6). After the roll R is set, the CPU 201 switches the arm member 4 to a state (strong nip state) in which the arm member 4 is pressed in the direction of the arrow A1 by the "strong nip pressing force" (step S2 in FIG. 6).

In the sheet leading edge setting process (step S3 in FIG. 6), the CPU 201 rotates the roll R in the direction opposite to the arrow C2 (reverse rotation) (step S21) and saves the sensor output (step S22). The CPU 201 may, for example, rotate the roll R at a constant speed and store the sensor output at constant time intervals. Further, in order to specify the position of the leading edge of the sheet 1 more accurately, the sensor output may be stored in synchronization with the pulse of the roll rotation amount sensor 36 (see FIG. 5) output according to the rotation amount of the roll R. In this case, it need not be constant on the roll R rotation side. As the sensor output, it is sufficient if data can be collected while the roll R rotates once. However, considering the slack of the sea and 1 when the roll R is set, the roll R is rotated one and a half turns (540 degrees or more in this example) to collect data (step S23).

After completing the data collection, the CPU 201 stops the rotation of the roll R (step S24), and extracts the maximum value Hd and the minimum value Ld of the sensor output from the sensor output data stored in the RAM 203 (step S25). After that, it is determined whether or not the difference (Hd-Ld) between the maximum value Hd and the minimum value Ld exceeds the value (THa) required to specify the position of the leading edge of the sheet 1 (step S26). The threshold value THa may be a fixed value, or may be set for each type of sheet 1 . Further, the value THa may be changed according to a high-humidity environment in which the sheet 1 swells, or a low-temperature, low-humidity environment in which the sheet 1 becomes stiff.

When the difference (Hd-Ld) exceeds the value (THa), the CPU 201 calculates thresholds THd1 and THd2 for determining the H level and L level of the sensor output based on the maximum value Hd and the minimum value Ld (steps S26 and S27). The thresholds THd1 and THd2 are set as independent thresholds with hysteresis in consideration of the noise variation wn due to signal disturbance. The change of the sensor output from H level to L level is determined using threshold THd1, and the change from L level to H level is determined using threshold THd2. The reason why the threshold values THd1 and THd2 are set based on the data of the sensor output when the roll R is rotated is that the light reflection characteristics differ depending on the type of sheet, and therefore the sensor output value of the sensor unit 6 may fluctuate. When specifying the position of the leading edge of a known sheet, values stored in advance in the ROM 204 (see FIG. 5) may be set as the thresholds THd1 and THd2. If the SN ratio of the obtained maximum value Hd and minimum value Ld is sufficiently large, a single intermediate value between the maximum value Hd and the minimum value LdHd may be set as a threshold for determining a change from the H level to the L level and from the L level to the H level of the sensor output.

After that, the CPU 201 analyzes the sensor output data stored in the RAM 203, and obtains the duration PL of the L level after the change from the H level to the L level based on the data for one round of the roll R (step S28). As the L-level duration PL, the rotation angle of the roll R corresponding to the duration PL may be calculated based on the output pulse of the roll rotation amount sensor 36 (see FIG. 5) or data obtained at regular time intervals. When the sensor output changes multiple times so that there are a plurality of durations PLA corresponding to the rotation angle A or more of the roll R as the duration PL of the L level, the CPU 201 selects the maximum duration PLAmax among them (steps S29 and S30). After that, the CPU 201 specifies the separation position where the leading edge of the sheet 1 is separated from the surface of the roll R as shown in FIG. 9B (step S31). Specifically, as shown in FIG. 10A, the change point Pa of the sensor output immediately before the maximum duration PLAmax is specified. The change point Pa corresponds to the rotation position (separation position) when the leading edge 1 of the sheet 1 is separated from the surface of the roll R as shown in FIG. 9B. If there is only one duration PLA corresponding to the rotation angle A or more, the separation position of the leading edge of the sheet 1 is identified from the change point Pa of the sensor output immediately before the duration PLA (steps S32 and S33).

After the separation position of the leading edge of the sheet 1 is identified in step S31 or S33, the CPU 201 reverses the roll R in the arrow C2 direction to the separation position (step S34). As a result, the leading edge 1 of the sheet 1 is peeled off and separated from the surface of the roll R as shown in FIG. Therefore, by rotating the roll R forward in the direction of the arrow C1 (step S35), 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 (automatic loading).

If it is determined in step S26 that the difference (Hd-Ld) does not exceed the threshold value THa, and if it is determined in step S22 that there is no duration PLA corresponding to the rotation angle A or more, the process proceeds to step S36. In step S36, the rotation of the roll R is stopped, the user is notified that automatic loading could not be executed, and the user is urged to perform a manual operation for inserting the leading edge of the sheet 1 into the sheet supply path.

As described above, in the present embodiment, even when the output of the sensor unit 6 temporarily fluctuates, the rotational position (separation position) of the roll R when the leading edge of the sheet 1 separates from the roll R can be specified based on the sensor output when the roll R is rotated in the reverse direction. After that, the roll R is reversely rotated to the separation position, and then the roll R is forwardly rotated, so that the leading edge of the sheet 1 can be automatically inserted into the sheet supply path and sent out.

(Third embodiment)
FIG. 12 is a block diagram of the control system in the third embodiment of the invention. The sensor unit 6 is a sensor whose output changes according to the facing distance from the surface of the roll R, as in the first embodiment described above. In this embodiment, an LED driver 6e with a dimming function under the control of the CPU 201 is connected to the light emitting portion 6c of the LED, and the amplification factor of the light emission intensity of the light emitting portion 6c can be changed by adjusting the current flowing through the light emitting portion 6c. A current-voltage conversion circuit 6h and an amplifier circuit 6i are connected to the light receiving portion 6d of the photodiode, and the amplification factor of the light receiving sensitivity of the light receiving portion 6d can be changed by adjusting the resistance value of the digital potential meter 6f under the control of the CPU 201. Further, the sensor unit 6 is provided with an EEPROM 6g of non-volatile memory for storing the amplification factor of the sensor unit 6 (the amplification factor of the emission intensity of the light emitting part 6c and the amplification factor of the light receiving sensitivity of the light receiving part 6d).

FIG. 13 is an explanatory diagram of output waveforms of the sensor unit 6 when the roll R is rotated in reverse. When the maximum value Hd of the sensor output of the sensor unit 6 becomes larger than the upper limit judgment value THmax, there is a possibility that the sensor output is 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 not be sufficient. Further, when the difference between the maximum value Hd and the minimum value Ld is less than a predetermined value, the sensor output may be affected by steady noise, making it difficult to detect the position of the leading edge of the sheet 1 . Therefore, a determination value is also set for determining whether the difference between the maximum value Hd and the minimum value Ld is sufficient.

In the present 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 of the detection signal (sensor output) of the sensor unit 6 at that time.

FIG. 14 is a flowchart for explaining amplification factor adjustment processing for adjusting the amplification factor (sensor amplification factor) of the sensor unit 6 .

First, the CPU 201 initializes the data processing area to secure an area for processing the output data of the sensor unit 6 (step S41), and then sets the initial value of the amplification factor of the sensor (step S42). The gain of the sensor adjusted by the previous gain adjustment processing is stored in the EEPROM 6g, and the stored gain is set as the initial value. If the gain is not stored, a predetermined gain is set as the initial value. In that case, the initial value of the amplification factor may be set according to the type, winding diameter, width, etc. of the roll R input in advance through the operation panel 28 . The winding diameter and width of the roll R may be set in the main body of the printing apparatus, or may be set by a driver in a terminal such as a personal computer connected to the printing apparatus by wire or wirelessly. Furthermore, a temperature/humidity sensor may be provided to set the initial value of the amplification factor according to the environmental temperature and environmental humidity when the roll R is set.

Next, the CPU 201 rotates the roll R one or more times in the direction of the arrow C2, acquires the sensor output at that time (step S43), and obtains a moving average from the sensor output for each predetermined rotation angle of the roll R (step S44). In the case of this example, the sensor output for two rotations of the roll R is obtained, and a moving average is obtained for each predetermined rotation angle of the roll R. FIG. The maximum value Hd and the minimum value Ld of the moving averaged data are extracted (step S45), and it is determined whether the maximum value Hd is equal to or greater than the upper limit determination value THmax in FIG. 13 (step S46). When the maximum value Hd is equal to or greater than the upper limit determination value THmax, the CPU 201 determines whether or not the amplification factor of the light emission intensity of the light emitting portion 6c is within a predetermined range (within a first allowable range) (step S47). When the amplification factor of the light emission intensity of the light emitting section 6c is within the predetermined range, the CPU 201 reduces the amplification factor of the light emission intensity (step S48), and when it is outside the predetermined range, the CPU 201 reduces the amplification factor of the light reception intensity of the light receiving section 6d (step S49). This makes it possible to avoid a situation in which the sensor output saturates.

On the other hand, when the maximum value Hd is less than the upper limit judgment value THmax, the CPU 201 determines whether or not the minimum value Ld is less than the lower limit judgment value THmin (step S50). When the minimum value Ld is less than the lower limit determination value THmin, the CPU 201 determines whether or not the amplification factor of the light emission intensity of the light emitting section 6c is within a predetermined range (step S51). The CPU 201 then increases the amplification factor of the light emission intensity when the amplification factor of the light emission intensity of the light emitting part 6c is within the predetermined range (step S52), and increases the amplification factor of the light reception intensity of the light receiving part 6d when it is outside the predetermined range (step S53). Thereby, the detection sensitivity of the sensor unit 6 can be enhanced.

Further, when the minimum value Ld is equal to or greater than the lower limit determination value THmin, the CPU 201 determines whether or not the difference (Hd-Ld) between the maximum value Hd and the minimum value Ld is less than a predetermined determination value (step S51). If the difference (Hd−Ld) is less than the predetermined judgment value, the sensor output may be affected by steady noise, making it difficult to detect the position of the leading edge of the sheet 1 . In this case, in order to increase the amplification factor of the light emission intensity or light reception intensity of the sensor unit 6, the process proceeds from step S4 to step S51. If the difference (Hd-Ld) is equal to or greater than the predetermined judgment value, it is determined that the amplification factors of the light emission intensity and the light reception intensity of the sensor unit 6 have been appropriately adjusted, and the amplification factor adjustment process is terminated.

After adjusting the amplification factor of the emitted light intensity or the received light intensity in the previous steps 48, S49, S52, and S53, the CPU 201 determines whether or not the amplification factor is within a predetermined range (step S55). That is, it is determined whether or not the light emission intensity is within a predetermined range (within a first allowable range) and the received light intensity is within a predetermined range (within a second allowable range). If the amplification factors of the emitted light intensity and the received light intensity are within the predetermined range, the process returns to the previous step S41 to reconfirm whether or not the amplification factors are appropriate. If the amplification factor of the emitted light intensity and the received light intensity is not within the predetermined range, it is determined that the amplification factor exceeds the adjustment limit, and error processing such as outputting an error display is executed. When the amplification factors of the emitted light intensity and the received light intensity are within a predetermined range, in steps 48, S49, S52, and S53, the number of times the amplification factors are increased and decreased may be counted, and error processing may be executed when the count value is equal to or greater than a predetermined number.

As described above, in the present embodiment, the output of the sensor unit 6 can be optimized by adjusting the amplification factor of the light emission intensity and the light reception intensity of the sensor unit 6 based on the sensor output when the roll R is reversely rotated by one or more rotations. Therefore, it is possible to reliably specify the positions of the leading ends of various sheets 1 having different reflectances.

(Fourth embodiment)
15 to 17 are diagrams for explaining the fourth embodiment of the present invention.

15A and 15B are diagrams for explaining the position of the sensor unit 6 arranged on the arm member of the sheet feeding device 200. In FIG. 15A, a roll R with a large winding diameter is set, and in FIG. 15B, a roll R with a small winding diameter is set. In this embodiment, the sensor unit 6 is arranged so as to satisfy the positional relationship of the following formula (1) regardless of the winding diameter of the roll R as shown in FIGS. 15(a) and 15(b). Further, when the roll R is formed by winding the sheet 1 around a tube such as a paper tube, the positional relationship of the following formula (1) is established even when only the tube such as the paper tube is set and the roll R has the minimum winding diameter.
α>β (α1>β1, α2>β2) (1)

In FIG. 15(a), let α1 be the distance between a position P1 where the roll R contacts the separation flapper 10a (contact position of the upper guide with respect to the roll R) and a position P2 where the roll R contacts the rotary follower 8 (contact position of the lower guide with respect to the roll). Also, let α2 be the distance between the position P1 and the position P2 in FIG. 15(b). These distances α1 and α1 are collectively referred to as distance α. In FIG. 15(a), the distance between the detection position of the sensor unit 6 and the position P2 is β1, and in FIG. 15(b), the distance between the detection position of the sensor unit 6 and the position P2 is β2. These distances β1 and β1 are collectively referred to as distance β. The detection position of the sensor unit 6 is the position of the detection portion of the sensor unit 6 that can detect the position of the tip, and corresponds to, for example, the positions of the light emitting portion 6c and the light receiving portion 6d.

In this way, the sensor unit 6 is positioned on the arm member so that the distance β1 is smaller than the distance α1 as shown in FIG. 15(a) and the distance β2 is smaller than the distance α2 as shown in FIG. 15(b). That is, regardless of the winding diameter of the roll R, the deployment position of the sensor unit 6 is set so as to satisfy the relationship α>β.

16A and 16B are explanatory diagrams of the light emitting optical axis of the light emitting portion 6c in the sensor unit 6. In FIG. 16A, a roll R with a large winding diameter is set, and in FIG. 16B, a roll R with a small winding diameter is set. Both the angle γ1 between the light emission optical axis I1 of the light emitting portion 6c and the vector Q1 in FIG. 16A and the angle γ2 between the light emission optical axis I2 and the vector Q2 of the light emitting portion 6c in FIG.
0°<γ(γ1, γ2)<90° (2)

A vector Q1 is a vector along a tangent line at an intersection point P3 between the optical axis I1 and the roll R, and directed in the forward rotation direction of the roll R (the direction of the arrow C1). Similarly, a vector Q2 is a vector that points in the forward rotation direction of the roll R along the tangent line at the intersection point P3 between the optical axis I2 and the roll R. The optical axes I1 and I2 are collectively referred to as the optical axis I, the vectors Q1 and Q2 are collectively referred to as the vector Q, and the angles γ1 and γ2 are collectively referred to as the angle γ.

In this way, the sensor unit 6 is arranged so that the angle γ (γ1, γ2) between the virtual line extending the optical axis I (I1, I2) inside the roll R and the vector Q (Q1, Q2) is an acute angle.

FIG. 17 is an explanatory diagram of the positional relationship between the light-emitting portion 6c and the light-receiving portion 6d in the sensor unit 6. As shown in FIG. 17A is a view of the essential parts of the sheet feeding device 200 viewed from the X-axis direction, and FIG. 17B is a view of the main part viewed from the Z-axis direction.

In this embodiment, the light-emitting portion 6c and the light-receiving portion 6d are arranged side by side in the axial direction of the roll R (X-axis direction). By adjoining the light emitting portion 6c and the light receiving portion 6d in the roll R axial direction, the light emitting optical axis of the light emitting portion 6c and the light receiving optical axis of the light receiving portion 6d substantially face each other in the roll R axial direction. By arranging the light-emitting portion 6c and the light-receiving portion 6d in this manner, the facing distance between the leading edge of the sheet 1 and the sensor unit 6 can be detected regardless of the winding diameter of the roll R. That is, the position of the leading edge of the sheet 1 can be detected when the leading edge of the sheet 1 passes through the driven roller 10a of the separation flapper and drops onto the arm member 4 due to the reverse rotation of the roll R.

Further, by setting the angle γ to an acute angle, there is a state in which the light emitting optical axis I and the surface of the leading edge of the sheet 1 are perpendicular to each other during the period from when the leading edge 1 of the sheet 1 drops onto the arm member 4 due to the reverse rotation of the roll R until it passes over the sensor unit 6. That is, during the period from when the leading edge of the sheet 1 passes through the driven roller 10a of the separation flapper until it falls on the arm member 4 under its own weight, the light emitting optical axis I and the surface of the leading edge of the sheet 1 are at right angles at least temporarily. In such a right-angled state, the reflected light emitted from the light-emitting portion 6c and reflected by the surface of the leading end portion of the sheet 1 is detected by the light-receiving portion 6d as the strongest specularly reflected light. Further, by setting the angle formed between the surface of the arm member 4 on which the tip of the sheet 1 falls and the light emission optical axis I to be 90 degrees, when the tip of the sheet 1 follows the surface of the arm member 4, the light emission optical axis I and the surface of the tip of the sheet 1 are at right angles.

In this manner, there is a state in which the light receiving portion 6d receives the strongest specularly reflected light during the period from when the leading edge 1 of the sheet 1 falls on the arm member 4 to when it passes over the sensor unit 6. FIG. Therefore, when the leading edge 1 of the sheet 1 falls on the arm member 4 under its own weight, the sensor output of the sensor unit 6 more reliably becomes H level, and the sensor output necessary for specifying the position of the leading edge of the sheet 1 can be obtained more reliably.

Further, the light-emitting portion 6c and the light-receiving portion 6d are arranged side by side in the axial direction of the roll R, and the light-emitting optical axis and the light-receiving optical axis are substantially opposed to each other. As a result, the influence of the type of sheet 1, the change in the winding diameter of the roll R, the change in the behavior of the leading edge of the sheet 1, and the like on the sensor output can be suppressed. Further, in a series of sensor outputs, the ratio of the sensor output when the light receiving portion 6d receives specularly reflected light can be increased to suppress noise due to the influence of external light. If α < β, γ > 90° without satisfying the above formulas (1) and (2), the optical axis of the sensor unit 6 always faces the separation flapper 10, and the sensor output corresponding to the facing distance from the leading edge of the sheet 1 cannot be obtained.

The deployment position of the sensor unit 6 is not limited to the arm member, and may be deployed at a position other than the arm member in consideration of the optical characteristics of the sensor unit 6 and the like.

(Fifth embodiment)
18A and 18B are explanatory diagrams of the configuration of the sheet feeding device 200 according to the fifth embodiment of the present invention. In FIG. 18A, a roll R with a large winding diameter is set, and in FIG. 18B, a roll R with a small winding diameter is set.

In the present embodiment, the relationship between the arm member 4 and the vector W (W1, W2) pointing in the normal rotation direction of the roll R along the tangent line at the contact point between the roll R and the rotary follower 8 is specified. That is, regardless of the winding diameter of the roll R, the feeding device 200 is configured such that the intersection point P4 between the vector W (W1, W2) and the surface of the arm member 4 exists. Further, the intersection point P4 is located on the upstream side (left side in FIG. 18) in the conveying direction of the sheet 1 from the intersection point P5 between the light emitting optical axis I of the sensor unit 6 and the surface of the arm member 4 .

By configuring the feeding device 200 in this manner, the leading edge of the sheet 1 moves toward the arm member 4 along the vector W when the roll R is rotated in the direction of the arrow C1 to convey the sheet 1. As shown in FIG. Therefore, regardless of the winding diameter of the roll R, the leading edge of the sheet 1 is conveyed while being in contact with the arm member 4 . Further, since the intersection point P4 is positioned upstream in the conveying direction from the intersection point P5, the leading edge of the sheet 1 passes over the sensor unit 6 during the transportation process of the leading edge of the sheet 1 regardless of the winding diameter of the roll R. Therefore, the sensor unit 6 can more reliably detect the distance between the leading end of the sheet 1 and the sheet 1 regardless of the winding diameter of the roll R.

(Sixth embodiment)
19 and 21 are explanatory diagrams of the sixth embodiment of the present invention. FIG. 19(a) is an explanatory diagram of the output waveform of the sensor unit 6. FIG. FIG. 19B is an explanatory diagram of a state in which the leading edge of the sheet 1 is normally separated from the surface of the roll R, and FIG. 19C is an explanatory diagram of a state in which the amount of separation of the leading edge of the sheet 1 from the surface of the roll R is smaller than normal due to the influence of static electricity or the like. FIGS. 20(a), (b), and (c) are explanatory diagrams when the roll R is rotated forward in the direction of the arrow C1 from the state of FIG. 19(c). FIG. 21 is a flowchart for explaining sheet leading edge setting processing (automatic loading) in this embodiment.

As shown in FIG. 19(b), when the leading edge of the sheet 1 is normally separated from the surface of the roll R, the sensor output of the sensor unit 6 changes like the waveform W1 in FIG. 19(a). That is, the roll R starts to reverse in the direction of the arrow C2 from the state where the leading end of the sheet 1 is near the driven roller 10a, and when the roll R rotates about 45 degrees, the leading end of the sheet 1 passes through the driven roller 10a and falls. As a result, the sensor output changes from L level to H2 level. Further, when the roll R rotates about 90 degrees after starting to rotate, the leading edge of the sheet 1 passes over the sensor unit 6 as shown in FIG. 19B, and the sensor output changes from H level to L level. After that, by rotating the roll R forward in the direction of the arrow C1, the leading edge of the sheet 1 can be automatically inserted into the sheet supply path and sent out.

On the other hand, as shown in FIG. 19(c), when the peeling amount of the leading edge of the sheet 1 is smaller than normal, the sensor output of the sensor unit 6 changes as shown by waveform W2 in FIG. 19(a). That is, the roll R starts to reverse in the direction of the arrow C2 from the state where the leading end of the sheet 1 is near the driven roller 10a, and when the roll R rotates about 45 degrees, the leading end of the sheet 1 passes through the driven roller 10a and falls. Further, when the roll R rotates about 90 degrees after starting to rotate, the leading edge of the sheet 1 passes over the sensor unit 6 as shown in FIG. 19C, and the sensor output changes from H level to L level. After that, when the roll R is rotated in the direction of the arrow C1, the peeling amount of the leading edge of the sheet 1 is small as shown in FIG.

The sheet leading edge setting process (automatic loading) in FIG. 21 in this embodiment suppresses the occurrence of such a jam. The same step numbers are assigned to the same processes as those in the flowchart of FIG. 8 of the above-described embodiment, and the description thereof is omitted.

Before starting the sheet leading edge setting process, the CPU 201 first determines whether or not the roll R is set (step S1 in FIG. 6). After the roll R is set, the CPU 201 switches the arm member 4 to a state (strong nip state) in which the arm member 4 is pressed in the direction of the arrow A1 by the "strong nip pressing force" (step S2 in FIG. 6).

In the sheet leading edge setting process, the CPU 201 rotates the roll R one or more times (reverse rotation) in the direction opposite to the arrow C2 (step S11).

The CPU 201 obtains the amount of change (level change amount) when the sensor output of the sensor unit 6 changes from the H level to the L level during reverse rotation of the roll R, and determines whether or not the level change amount is greater than a predetermined threshold value ΔH1 (=H1−L) (step S61). When the level change amount does not exceed a predetermined threshold value ΔH1 (=H1−L) even when the roll R rotates in the opposite direction for one or more rotations, it is determined that the leading edge of the sheet 1 has not been peeled off from the surface of the roll R, and the process proceeds to step S17. In step S17, as described above, the user is prompted to perform a manual operation for inserting the leading edge of the sheet 1 into the sheet supply path. Therefore, the threshold value ΔH1 serves as a criterion for determining whether or not the leading edge of the sheet 1 is separated from the surface of the roll R. L is the lowest level of the sensor output.

The CPU 201 determines that the leading edge of the sheet 1 has separated from the surface of the roll R as shown in FIG. Then, the rotation of the roll R is stopped under the condition that the sensor output has continued to be at the L level for a certain period of time (steps S13 and S14). After that, the CPU 201 determines whether or not the amount of change in level of the sensor output is greater than a predetermined threshold value ΔH2 (=H2−L) (step S62). When the level change amount is larger than the threshold value ΔH2, as shown in FIG. 19(b), it is determined that the leading end portion has normally separated from the surface of the roll R, and automatic loading is executed (step S15). On the other hand, when the level change amount is not larger than the threshold value ΔH2, it is determined that the peeling amount of the leading edge of the sheet 1 from the surface of the roll R is smaller than normal, as shown in FIG. 19C. In this way, when the peeling amount of the leading edge of the sheet 1 is smaller than normal, automatic loading of the sheet 1 is possible depending on the rigidity of the sheet 1, so it is determined whether the rigidity of the sheet 1 is equal to or higher than a predetermined value (step S63). The stiffness of the seat 1 is determined, for example, based on information about the type of the seat 1 input by the user. The criteria for determining the stiffness of the sheet 1 may be set according to the information on the type of the sheet 1, the width size of the sheet 1, the use state of the sheet 1, the use environment of the printing apparatus, and the like. When the stiffness of the sheet 1 is equal to or higher than a predetermined value, the process proceeds to step S15 to execute automatic loading, and when the stiffness of the sheet 1 is less than the predetermined value, the process proceeds to step S17 to prompt the user to perform manual operation for inserting the leading edge of the sheet 1 into the sheet supply path.

In this manner, the peeling amount of the leading edge of the sheet 1 is detected according to the sensor output of the sensor unit 6, and automatic loading is executed on the premise that the peeling amount and the stiffness of the sheet 1 satisfy predetermined conditions. As a result, it is possible to avoid jamming of the sheet 1 in the printing apparatus.

(Seventh embodiment)
22 and 23 are explanatory diagrams of the seventh embodiment of the present invention. In this embodiment, when the leading edge of the sheet 1 cannot be automatically fed into the sheet supply path, i.e., when automatic loading cannot be executed, the leading edge of the sheet 1 is positioned within a predetermined range for manual feeding. FIG. 22 is an explanatory diagram of the stop position of the leading edge of the sheet 1, and FIG. 23 is a flowchart for explaining sheet leading edge setting processing (automatic loading) in this embodiment.

When the leading edge of the sheet 1 cannot be automatically fed into the sheet supply path, as shown in FIG. 22, the roll R is reversely rotated in the direction of the arrow C2 so that the leading edge of the sheet 1 is positioned within the range θ1 (within the visible range) between the driven roller 10a and the driven rotating body 9. The range θ1 includes the range of the circumferential surface of the roll R that can be visually observed by the user when the roll R is attached to or detached from the printing apparatus. By positioning the leading edge of the sheet 1 within such a range θ1, the user can visually recognize the leading edge of the sheet 1, thereby improving workability of manual operation for inserting the leading edge of the sheet 1 into the sheet supply path.

In the sheet leading edge setting process of the present embodiment, as shown in FIG. 23, an operation (step S71) for stopping the leading edge of the sheet 1 at a position within a predetermined range θ1 is added to the sheet leading edge setting process of FIG. 21 in the sixth embodiment. The CPU 201 identifies the position of the leading edge of the sheet 1 based on the processing information of steps S61, S13, and S16, then stops the rotation of the roll R (step S14), and then compares the level change amount of the sensor output with the threshold value ΔH2 (step S62). When the level change amount is larger than the threshold value ΔH2, as described above, it is determined that the leading edge of the sheet 1 has been normally separated from the surface of the roll R, and automatic loading is executed (step S15). If the level change amount is not larger than the threshold value ΔH2, as described above, automatic loading is executed on the condition that the stiffness of the seat 1 is equal to or higher than the predetermined value (steps S63 and S15). When the stiffness of the sheet 1 is less than a predetermined value, the stiffness of the sheet 1 is low and jamming may occur. Therefore, the roll R is reversely rotated in the direction of the arrow C2 so that the leading edge of the sheet 1 whose position is specified in the previous steps S61, S13, and S16 is positioned within the range θ1. After that, the process proceeds to step S17 to prompt the user to perform a manual operation to insert the leading edge of the sheet 1 into the sheet supply path.

In this way, by positioning the leading edge of the sheet 1 within a predetermined range where the user can visually recognize the leading edge, the visibility of the leading edge of the sheet 1 by the user can be improved. In addition, the user can smoothly insert the leading edge of the sheet 1 into the sheet supply path by combining with the warning by the display on the panel or the like. This allows the user to easily perform manual paper feeding.

In this example, from the viewpoint of the user's visibility of the leading edge of the sheet 1, the range θ1 between the driven roller 10a and the driven rotating body 9 is set as the stopping position of the leading edge of the sheet 1, as shown in FIG. However, the leading edge of the sheet 1 may be stopped in a range different from the range θ1 between the driven roller 10a and the driven rotating body 9 in order to reduce the amount of rotation of the roll R and shorten the time required for the manual operation of inserting the leading edge of the sheet 1.

(Modification)
The sensor unit 6 is not limited to an optical sensor, and a distance sensor other than an optical sensor can be used as long as the sensor changes its output value according to the distance to the outer surface of the sheet to be detected. For example, a distance sensor such as an ultrasonic sensor or an electrostatic sensor that detects the distance to the object without contact can be used.

The printing apparatus is not limited to the configuration including two sheet supply devices corresponding to the two roll sheets, and may be configured to include one sheet supply device or three or more sheet supply devices. Further, the printing device is not limited to an inkjet printing device as long as it prints an image on a sheet supplied from a sheet feeding device. Also, the printing method and configuration of the printing device are arbitrary. For example, it may be either a serial scan method in which an image is printed by repeating print head scanning and a sheet conveying operation, or a full line method in which an image is printed by continuously conveying a sheet to a position facing a long print head.

Further, the present invention can be applied to various sheet feeding devices other than a sheet feeding device that feeds a sheet as a print medium to a printing device. For example, it can be applied to a device that supplies a sheet to be read to a reading device such as a scanner or a copier, and a device that supplies a sheet-like processing material to a processing device such as a cutting device. Such a sheet feeding device can be configured separately from devices such as a printing device, a reading device, and a processing device, and may include a control unit (CPU) for the sheet feeding device.

As described above, the sheet feeding device is not limited to the configuration in which the driven rotating bodies 8 and 9 connected to the arm member 4 are pressed against the roll R from below and the position of the tip of the roll R is detected using the sensor unit 6 mounted on the arm member 4. For example, as shown in FIG. 24, the driven rotors 8 and 9 and the sensor unit 6 may be arranged on a fixed structure 40 provided below the roll R, and the roll R may be pressed against the driven rotors 8 and 9 by the weight of the roll R regardless of the winding diameter of the roll R. Alternatively, the roll R may be brought into pressure contact with the driven rotating bodies 8 and 9 using a driving mechanism (not shown).

INDUSTRIAL APPLICABILITY The present invention can be widely applied to various sheet feeding devices including paper, film, cloth, etc., and various sheet processing devices such as printing devices and image reading devices including such feeding devices. The image reading device reads the recorded image on the sheet fed from the feeding device with a reading head. Further, the sheet processing device is not limited to the printing device and the image reading device, and may be any device that performs various processes (processing, coating, irradiation, inspection, etc.) on the sheet supplied from the feeding device. When the sheet feeding device is constructed as an independent device, the device can be provided with a control section including a CPU. Further, when a sheet feeding device is provided in the sheet processing apparatus, at least one of the feeding device and the sheet processing device can be provided with a control section including a CPU.

1 seat 6 sensor unit (sensor)
6c light-emitting portion 6d light-receiving portion 4b guide portion (lower guide)
10 separation flapper (upper guide)
100 printing device 200 sheet feeding device 400 printing section R roll

Claims (12)

a holding part that rotatably holds a rotating shaft of a roll formed by winding a sheet at a fixed position;
driving means for rotationally driving the rotating shaft to rotate the roll in a first direction for sending out the sheet from the roll held by the holding portion and in a second direction opposite to the first direction;
detection means for detecting the leading edge of the sheet on the roll;
a first contact member that contacts the roll;
a second contact member that contacts a roll, and feeds a sheet in a region upstream of the first contact member and downstream of the second contact member in the second direction of the roll,
After rotating the roll in the second direction by the driving means and detecting the leading edge of the sheet based on the output from the detecting means, the roll is rotated in the second direction by the driving means based on the angle of the rotation shaft for the leading edge of the sheet to pass through the second contact member and reach the area, and when the leading edge of the sheet reaches the area from outside the area , rotation of the roll is changed from the second direction to the first direction. 2. The sheet feeding apparatus according to claim 1, further comprising a lower guide that supports the sheet delivered from the roll from below, and wherein the first contact member is provided on the lower guide. 3. The sheet feeding device according to claim 2, wherein the lower guide moves according to the outer diameter of the roll. a pressing member that presses the lower guide;
4. The sheet feeding apparatus according to claim 2, further comprising switching means for switching the force of the pressing member pressing the lower guide. 5. The sheet feeding apparatus according to claim 2, wherein the detection means is provided in the lower guide, and the detection means is positioned downstream of the first contact member in the moving direction of the sheet delivered from the roll. 6. The sheet feeding apparatus according to claim 1, wherein the leading edge of the sheet of the roll rotating in the second direction is separated from the roll after passing through the second contact member, and the sheet approaches the detecting means. 7. The sheet feeding device according to claim 1, further comprising an upper guide for regulating the sheet above the sheet delivered from the roll, wherein the second contact member is provided on the upper guide. 8. The sheet feeding device according to claim 7, wherein the upper guide moves according to the outer diameter of the roll. 9. The sheet feeding apparatus according to claim 1, wherein said detecting means is provided in said area. 10. The sheet feeding apparatus according to any one of claims 1 to 9, further comprising a rotation amount sensor for detecting the amount of rotation of the roll, wherein the position of the leading edge of the sheet on the roll is specified based on the output from the detection means and the rotation angle of the roll from the rotation amount sensor corresponding to the output, and the leading edge of the sheet is caused to reach the area based on the position. 11. The sheet feeding device according to any one of claims 1 to 10, wherein the roll rotates in the second direction within a range of more than one rotation but not more than three rotations before changing rotation in the first direction. a sheet feeding device according to any one of claims 1 to 11;
and printing means for printing an image on the sheet supplied from the sheet supply device.

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