Paper feeder and image forming apparatus

Abstract

To provide a paper feeder capable of automatically accurately detecting that no roll paper is set up without increasing the number of parts and of preventing processing for a case where the roll paper is set up from being carried out despite no roll paper set up.SOLUTION: A paper feeder includes an arm 91 having a sensor 93 and a roll 92 arranged and supporting the sensor and a roll unit so that the sensor and the roll unit abut on a surface of a roll paper. The roll paper has inside a paper tube so as to insert a cylindrical spool inside the paper tube and be attached on the paper feeder, thus being rotated in conjunction with a rotation of the spool. The roll is arranged in a different position from the sensor in a circumferential direction of the roll paper. The sensor has a detection accuracy to detect a step at a tip of the roll paper. The arm 91 is rotatable and to rotate in a range where the sensor is out of contact with the spool. By detecting an inclination K1 of a sensor signal at a passage of a tip of the roll paper through the roll unit and an inclination K2 of a sensor signal at a passage of the tip of the roll paper through the sensor, a presence / absence of a tip of the roll paper is determined.SELECTED DRAWING: Figure 10

Description

[Technical Field]

[0001] The present invention relates to a paper feeder and an image forming apparatus. [Background technology]

[0002] In image forming devices that use roll paper, it is known that the roll paper is set on a spool and placed in a holder of the paper feeder, and then the paper feeder performs a paper feeding operation. In such devices, a technique for detecting the leading edge of the roll paper is known.

[0003] Patent Document 1 discloses a configuration for detecting the leading edge of roll paper by rotating the roll paper in the winding direction and detecting the leading edge of the peeled paper using a sensor (the output value changes depending on the distance to the peeled paper). According to Patent Document 1, this makes it possible to more reliably perform automatic paper feeding of the installed roll.

[0004] Patent Document 2 discloses a paper feeder that includes a support member on which a sensor and rollers are arranged, and the sensor has the detection accuracy to detect the step at the leading edge of the roll paper. According to Patent Document 2, the leading edge of the roll paper can be stably detected and the paper can be transported to the paper feed section. Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the prior art, when a spool without roll paper was inserted into the paper feeder, the printer would sometimes perform the same process as if roll paper had been inserted, even though no roll paper was actually inserted. This required the operator to first cancel the process, which required extra time and effort on the part of the operator. Other issues included the need to shut down the printer and then restart it.

[0006] Furthermore, conventional technologies have had problems such as the need for a large number of components to detect when roll paper is not installed, and the inability to improve detection accuracy. For example, a reflective sensor can be used to detect whether the paper is roll paper or the spool shaft by examining the difference in reflectivity between the surface of the roll paper and the surface of the spool shaft. However, this method has problems such as the increased number of components due to the additional sensor, which leads to increased costs, and the possibility of false detection due to the influence of external light. Therefore, there is a need to improve the accuracy of detecting when roll paper is not installed.

[0007] To provide a paper feeder that can automatically and accurately detect that roll paper is not set without increasing the number of parts, and can prevent processing that would be performed if roll paper were set even when roll paper is not set. [Means for solving the problem]

[0008] In order to solve the above problem, the paper feeder of the present invention is a paper feeder that supplies paper from a roll of long paper, the paper feeder comprising: a support member that supports a sensor and a roller portion so that the sensor and the roller portion contact the surface of the roll paper; and a control unit that acquires a signal from the sensor, The roll paper has a paper tube inside, a spool is inserted inside the paper tube, and the roll paper is provided in the paper feed device, and rotates in conjunction with the rotation of the spool, The sensor and the roller portion are disposed toward the axial center of the spool, the roller portion is disposed at a different position from the sensor in the circumferential direction of the roll paper, the sensor has a detection accuracy capable of detecting a step at the leading edge of the roll paper, the control unit detects the presence or absence of the leading edge of the roll paper by detecting a slope K1 of the sensor signal when the leading edge of the roll paper passes the roller unit and a slope K2 of the sensor signal when the leading edge of the roll paper passes the sensor; The support member is rotatable and is characterized in that it rotates within a range where the sensor does not come into contact with the spool. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a paper feeder that can automatically and accurately detect that roll paper is not set without increasing the number of parts, and that can prevent processing that would be performed as if roll paper were set even when roll paper is not set. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an example of a schematic configuration of an image forming apparatus according to an embodiment; [Figure 2] 1 is a schematic cross-sectional view illustrating an example of the configuration of an image forming apparatus according to an embodiment. [Figure 3] FIG. 10 is a diagram illustrating a conventional method for setting roll paper. [Figure 4] 10A and 10B are diagrams illustrating a method for setting roll paper on a spool. [Figure 5] 1 is a side view illustrating a main part of a configuration example of a paper feed device according to an embodiment. [Figure 6] FIG. 2 is a functional block diagram illustrating an example of functions of a paper feed device according to an embodiment. [Figure 7] 1A and 1B are diagrams illustrating an example of the configuration of an arm according to an embodiment. [Figure 8] 10A and 10B are diagrams illustrating an example of an operation for detecting the leading edge of roll paper. [Figure 9] 10A and 10B are diagrams illustrating differences due to the positional relationship between a roller and a sensor. [Figure 10] 1A is a diagram showing an example of the positional relationship between a roller, a sensor, and the leading edge of roll paper, and FIG. 1B is a diagram showing an example of a signal waveform of the sensor. [Figure 11] 10A to 10C are diagrams illustrating an example of the movements of the roller, sensor, and arm when the position of the leading edge of the roll paper changes. [Figure 12] FIG. 12 is a diagram showing an example of a signal waveform of a sensor in FIG. [Figure 13] 10A to 10D are diagrams illustrating an example of the movement of the roller and the arm when the position of the leading edge of the roll paper changes. [Figure 14] 14(a) to 14(d) are diagrams illustrating an example of the movement of the sensor when the position of the leading edge of the roll paper changes as shown in FIG. 13. [Figure 15] 15(e) to 15(h) are diagrams illustrating an example of the movement of the sensor when the position of the leading edge of the roll paper changes further from that in FIG. 14. [Figure 16] 13 is a diagram for explaining details of the signal waveform of the sensor shown in FIG. 12. FIG. [Figure 17] 10A and 10B are diagrams illustrating an example of a signal waveform of a sensor when a detection operation is repeated. [Figure 18] 10 is a flowchart illustrating an example of a process from setting roll paper to performing a paper transport operation. [Figure 19] 19 is a flowchart illustrating part A of FIG. 18. [Figure 20] 20 is a flowchart illustrating part E of FIG. 19. [Figure 21] FIG. 28 is a diagram for explaining symbols used in the flowcharts shown in FIGS. 19, 20 and 27. [Figure 22] FIG. 10 is a diagram showing an example in which there is no roll paper and a paper tube is set. [Figure 23] FIG. 10 is a diagram showing an example in which only a spool is set in a conventional example. [Figure 24] FIG. 10 is a diagram illustrating an example in which only a spool is set in an embodiment. [Figure 25] 1A shows an example of a signal waveform of the sensor when it is in contact with the surface of the paper tube or spool, and FIG. 1B shows an example of a signal waveform of the sensor when it is not in contact. [Figure 26] FIG. 10 is a diagram showing another example of a signal waveform of the sensor. [Figure 27] 19 is a flowchart illustrating another example of part A of FIG. 18. [Figure 28]19 is a flowchart illustrating another example of part A of FIG. 18. DETAILED DESCRIPTION OF THE INVENTION

[0011] The paper feeder and image forming apparatus according to the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments, and can be modified, added, modified, deleted, or otherwise altered within the scope of what one skilled in the art can conceive. Any embodiment that achieves the functions and effects of the present invention is within the scope of the present invention.

[0012] The paper feeder of the present invention is a paper feeder that supplies paper from a roll of long paper, a support member that supports a sensor and a roller portion so that the sensor and the roller portion contact the surface of the roll paper; and a control unit that acquires a signal from the sensor, The roll paper has a paper tube inside, a spool is inserted inside the paper tube, and the roll paper is provided in the paper feed device, and rotates in conjunction with the rotation of the spool, The sensor and the roller portion are disposed toward the axial center of the spool, the roller portion is disposed at a different position from the sensor in the circumferential direction of the roll paper, the sensor has a detection accuracy capable of detecting a step at the leading edge of the roll paper, the control unit detects the presence or absence of the leading edge of the roll paper by detecting a slope K1 of the sensor signal when the leading edge of the roll paper passes the roller unit and a slope K2 of the sensor signal when the leading edge of the roll paper passes the sensor; The support member is rotatable and is characterized in that it rotates within a range where the sensor does not come into contact with the spool.

[0013] The paper feeder of the present invention is a paper feeder that supplies paper from a roll of long paper, the roll comprising: a support member that supports a sensor and a roller portion so that the sensor and the roller portion contact the surface of the roll paper; and a control unit that acquires a signal from the sensor, The roll paper has a paper tube inside, a spool is inserted inside the paper tube, and the roll paper is provided in the paper feed device, and rotates in conjunction with the rotation of the spool, The sensor and the roller portion are disposed toward the axial center of the spool, the roller portion is disposed at a different position from the sensor in the circumferential direction of the roll paper, the sensor has a detection accuracy capable of detecting a step at the leading edge of the roll paper, the support member is rotatable and rotates within a range where the sensor does not come into contact with the spool; The control unit detects the slope K2 of the sensor signal when the leading edge of the roll paper passes the sensor, and when the slope K2 is detected on the nth rotation of the roll paper or the spool, determines whether the slope K2 is detected again on the n+1th rotation, and determines that the leading edge of the roll paper is present if the slope K2 is detected continuously for a predetermined number of rotations. Here, n is an integer of 1 or more.

[0014] According to the present invention, it is possible to automatically and accurately detect that roll paper is not set without increasing the number of parts, and to prevent the process for when roll paper is set from being performed even though roll paper is not set.

[0015] The paper feeder of this embodiment supplies paper from a roll of paper, which is a recording medium made of a long piece of paper (also called a "sheet") wound into a roll.

[0016] An example of the configuration of an image forming apparatus to which a paper feeder according to an embodiment of the present invention is applied will be described with reference to FIGS. An image forming apparatus according to one embodiment of the present invention is an inkjet printer that prints on a recording medium by ejecting ink droplets in accordance with image data, but the present invention can also be applied to electrophotographic copying machines and printers that transport a recording medium and print.

[0017] Fig. 1 is a perspective view of a schematic configuration example of an image forming apparatus 80 according to one embodiment, and Fig. 2 is a side cross-sectional view of the image forming apparatus, and the overall configuration of the image forming apparatus according to one embodiment and the operation of its main parts will be described. In Fig. 1, arrows indicate X, Y, and Z, respectively, in the depth direction (front-rear direction) of the image forming apparatus 80, width direction (main scanning direction) of the image forming apparatus 80, and up-down direction.

[0018] 1, image forming apparatus 80 is a serial liquid ejection type (ink ejection type) image forming apparatus, and has a main body housing 81 disposed on a main body frame 82. In image forming apparatus 80, a main guide rod 64 and a sub guide rod 65 are stretched across the main scanning direction indicated by double-headed arrow Y in FIG. 1 within main body housing 81. Main guide rod 64 movably supports carriage 66, and carriage 66 is provided with a connecting piece 66a that engages with sub guide rod 65 to stabilize the position of carriage 66.

[0019] In the image forming device 80, an endless timing belt 67 is disposed along a main guide rod 64, and the timing belt 67 is stretched between a drive pulley 68 and a driven pulley 69. The drive pulley 68 is driven to rotate by a main scanning motor 70, and the driven pulley 69 is disposed in a state in which it applies a predetermined tension to the timing belt 67. The drive pulley 68 is driven to rotate by the main scanning motor 70, and thereby causes the timing belt 67 to rotate in the main scanning direction according to the direction of rotation of the drive pulley 68.

[0020] The carriage 66 is connected to a timing belt 67, and when the timing belt 67 is rotated in the main scanning direction by a drive pulley 68, the carriage 66 moves back and forth in the main scanning direction along the main guide rod 64.

[0021] In the image forming device 80, a cartridge unit 71 and a maintenance mechanism unit 72 are detachably housed at an end position in the main scanning direction within a main body housing 81. Cartridge unit 71 houses replaceable cartridges 73, each containing yellow (Y), magenta (M), cyan (C), and black (K) ink. Each cartridge in cartridge unit 71 is connected by a pipe (not shown) to a recording head of the corresponding color among the recording heads (not shown) mounted on carriage 66, and ink is supplied from cartridge unit 71 to the recording head of each color through the pipe.

[0022] The image forming device 80 records an image on the paper P by ejecting ink onto the paper P, which is transported intermittently in a sub-scanning direction (the direction of arrow X in Figure 1) perpendicular to the main scanning direction, on a platen (plate) 74 (see Figure 2) while moving the carriage 66 in the main scanning direction.

[0023] The paper P is not limited to paper, and various types such as rolled film can be used. However, in the following explanation, for clarity, the paper being transported will be referred to as paper P, the rolled state of paper P will be referred to as roll paper Pr (Pa, Pb), and the core tube (core portion) of roll paper Pr will be referred to as Ps.

[0024] As shown in FIG. 2, the image forming device 80 has a chamber 75 with a fan disposed below the platen 74, and by driving the fan, the paper P transported on the platen 74 is transported in close contact with the platen 74.

[0025] The image forming device 80 intermittently transports paper P in the sub-scanning direction, and while the transport of paper P in the sub-scanning direction is stopped, it moves the carriage 66 in the main scanning direction and ejects ink from the nozzle array of the recording head mounted on the carriage 66 onto the paper P on the platen 74, thereby forming (recording) an image on the rolled paper P.

[0026] The maintenance mechanism 72 cleans the ejection surface of the print head, caps it, ejects unnecessary ink, etc., in order to discharge unnecessary ink from the print head and maintain the reliability of the print head.

[0027] In the image forming device 80, an encoder sheet (not shown) is disposed parallel to the timing belt 67 and the main guide rod 64, at least over the range of movement of the carriage 66. An encoder sensor that reads the encoder sheet is attached to the carriage 66. The image forming device 80 controls the movement of the carriage 66 in the main scanning direction by controlling the drive of the main scanning motor 70 based on the results of reading the encoder sheet by the encoder sensor.

[0028] In addition, a reflective sensor (encoder sensor, paper tip detection sensor) mounted on the carriage 66 detects both ends of the paper P transported to the image forming unit 60, and at that time, the size of the paper P is detected from the main scanning direction position read by the paper tip detection sensor.

[0029] In the image forming apparatus 80, as shown in FIGS. 1 and 2, two spool bearing pedestals 5a and 5b are provided on a main body frame 82 that supports a main body housing 81, in the vertical direction in FIGS.

[0030] Paper (rolled paper) P pulled out from the tip of the roll paper Pr set on the spool bearing bases 5a and 5b is transported within the transport path 9 by the transport roller pair 6a and 6b, the registration roller 10, and the registration pressure roller 17, as shown by the arrows in Figure 2. The control unit 110 controls the driving device 7 to rotate the pair of conveying rollers 6a and 6b, the registration roller 10, the registration pressure roller 17, and the like. Below the roll paper Pr (Pa, Pb), roll paper trays 8a, 8b are provided to prevent the roll paper Pr from falling.

[0031] The paper P passes through a transport path 9 supported by medium transport guide members 18a, 18b, etc., and is transported onto a platen 74 in the image forming unit 60.

[0032] In the image forming unit 60, an image is formed by a liquid recording head discharging droplets of each color onto the paper P in accordance with image data. A cutter 76 extending in the sub-scanning direction (paper width direction) is provided at the forward transport direction discharge section for the paper P on which the image has been formed, and is used to cut the paper P, which is made of continuous paper, to a predetermined length.

[0033] To align the leading edge of the transported continuous paper P, the cutter 76 is fixed to a wire or timing belt stretched between multiple pulleys (one of which is connected to a drive motor), and is moved in the main scanning direction Y by the drive motor to cut the paper P to a predetermined length. The cut paper P is then discharged to the discharge section. 1 and 2 show an example of the configuration of an image forming apparatus in which roll paper Pa and Pb can be set on two spool bearing pedestals 5a and 5b, but the image forming apparatus may also be one having one spool bearing pedestal. In addition, in the above explanation, the configurations corresponding to the two rolls of paper Pa and Pb were described using identifiers a and b (for example, spool bearing stands 5a and 5b), but hereafter, when there is no need to distinguish between them, the identifiers a and b will not be used.

[0034] In this embodiment, a sensor may be provided on the spool bearing pedestals 5a and 5b to detect whether a spool has been set. Such a sensor may be referred to as a spool detection sensor. Using a spool detection sensor makes it possible to detect whether roll paper has been set. Furthermore, when roll paper has been set, it becomes possible to perform processing such as displaying a paper feed screen.

[0035] Here, a conventional method for setting roll paper will be described. FIG. 3 is a diagram illustrating a conventional method for setting roll paper. The roll paper Pr has a flange (flange member) at the widthwise end, onto which the spool is set. The user places the roll paper with the spool set into the paper feeder receiver (spool bearing stand) of the device (Figure 3(A)), finds the leading edge of the roll paper, and while maintaining the leading edge, holds it down with both hands as shown in Figure 3(B), and rotates the roll paper so that the leading edge is facing forward. Next, the user positions the leading edge of the paper between the guide plates at the back of the roll and inserts it while rotating (Figure 3(C)). The guide plates are made of transparent material so that the paper can be seen, and consist of two plates, one above the other. The user rotates the roll paper so that the leading edge is at the top of the lower guide, and inserts the paper into the back of the guide, where it is fixed internally and pulled into the device.

[0036] As shown in Figure 3(C), the guide plate where the leading edge of the paper is inserted is located at the back of the roll paper, so it is hidden by the roll paper and difficult to see, and because the guide plate is also transparent, it can happen that when you think you have inserted the paper between two guide plates, it ends up being positioned above the upper guide plate, and you have to start over. Also, if the guide plate were not transparent, it would be difficult to check whether the paper was inserted between the two guide plates. In addition, the leading edge of the roll paper needs to be inserted as evenly as possible, which requires careful attention. If the leading edge of the paper is not inserted evenly, it will be fed at an angle, causing skew, which can lead to restarting the operation or causing jams.

[0037] Furthermore, as shown in Figures 3(D) and (E), in a device with a two-tiered roll paper setting section, if a roll paper is set in the upper tier and a roll paper is set in the lower tier and the leading edge is inserted between the guide plates, the guide plates are even more difficult to see because the roll paper in the upper tier is already there, making setting difficult and increasing the risk of inserting it at an angle.

[0038] Therefore, in one embodiment, a paper feeder is configured to detect the leading edge of roll paper by using a sensor to detect the step at the leading edge of the roll paper, and then transports the roll paper to the paper feed unit. The feed unit is a means for feeding the roll paper to a destination, such as the pair of transport rollers 6 or the transport path 9 in Figure 2.

[0039] Figure 4 is a diagram illustrating an example of setting roll paper on a spool. Figures 1 to 3 in Figure 4 show an example of removing old roll paper, and Figures 4 to 6 show an example of setting new roll paper. As shown in Figures 4, 1 to 3, flanges are provided on both ends of the spool, and after removing the flanges, the old roll paper is removed from the spool. Next, as shown in Figures 4, 4 to 6, the new roll paper is inserted into the spool and the flanges are set.

[0040] In the examples shown in 1 to 3 of Figure 4, old roll paper is used, but when there is no paper left, the paper tube inside the roll paper is removed from the spool. Roll paper has a paper tube inside, and the spool is inserted inside the paper tube and installed (set) in the paper feeder. In addition, by using a flange, for example, the roll paper can rotate in conjunction with the rotation of the spool, but this is not limited to a flange.

[0041] The spool may be referred to as a spool shaft or simply as a shaft. The spool is, for example, cylindrical, and the interior of the cylinder may or may not be hollow. The configuration of the spool is not particularly limited and can be selected appropriately. The spool is basically not in contact with the paper tube, but this does not exclude a configuration in which the spool and the paper tube are in contact.

[0042] FIG. 5 is a side view illustrating a main part of a configuration example of a paper feeder according to an embodiment. The paper feeder 90 includes at least an arm 91, a roller 92, a sensor 93, and a pair of transport rollers 6 as a transport unit. The paper feeder 90 may further include an entrance guide plate 95. 5, the dashed line indicates the position of roll paper Pr when the user sets roll paper Pr in paper feeder 90. Roll paper Pr is held by a module component (not shown) so that it can rotate around the center (axis) of the roll paper.

[0043] Arm (guide plate) 91, which serves as a support member for roll paper Pr, is configured to be rotatable around rotation center 911. Arm 91 is pressed toward the roll paper on one side of rotation center 911 by a spring or the like. This ensures that arm 91 remains in contact with the outer diameter of the roll paper even if the diameter of the roll paper changes. The outline arrow indicates the rotation direction of arm 91. The arm 91 also has a roller 92 and a sensor 93 on the other side of the rotation center 911. The arm 91 is pressed in the direction of the roll paper, so it supports the roller 92 and the sensor 93 so that they abut against the surface of the roll paper Pr.

[0044] The arm 91 functions as a guide plate that guides the paper feed direction of the roll paper Pr. The part of the arm 91 where the roll paper Pr is set (the end side) should be shaped to follow the outer diameter of the roll paper (for example, arc-shaped) so that the roll paper Pr is held in place (to prevent it from falling, etc.) when the user sets the roll paper Pr. The arm 91 also functions as the roll paper holder 8 in Figure 2. The arm 91 as a support member also serves as a guide plate for guiding the roll paper, thereby reducing the number of parts and making it possible to keep costs down.

[0045] The roller 92 and the sensor 93 are arranged so as to face substantially the center of the roll paper (so as to face the axial center of the roll paper) regardless of the diameter of the roll paper. The roller 92 is disposed at a different position from the sensor 93 in the circumferential direction of the roll paper Pr, and the roller 92 and the sensor 93 are disposed offset from each other in the circumferential direction. The sensor 93 has a detection accuracy that allows it to detect the step (paper thickness) at the leading edge of the roll paper Pr.

[0046] The entrance guide plate 95 guides the transport direction of the paper peeled from the roll paper Pr. In the configuration example of Figure 5, during paper feeding (when the roll paper Pr rotates forward), the arm 91, which functions as a guide plate, guides the paper on the upstream side of the paper transport direction, and the entrance guide plate 95 guides it on the downstream side.

[0047] Next, the control of the functions of the paper feeder will be described with reference to Fig. 6. Fig. 6 is a functional block diagram illustrating an example of the functions of the paper feeder according to an embodiment. The control unit 110 controls the entire paper feed device. Fig. 6 shows an example of a functional block in which the control unit 110 controls the sensor 93 and the motor drive circuit units 120 and 140, and other functional blocks are omitted. The functions of the control unit 110 may be configured to be executed by the control unit 110 (see Fig. 2) that controls the entire image forming apparatus.

[0048] The control unit 110 includes, for example, a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), and the like. The CPU executes various programs and controls the entire image processing apparatus based on arithmetic processing and control programs. RAM is a volatile storage medium for reading and writing information at high speed, and functions as a work area when the CPU executes programs. The ROM is a read-only non-volatile storage medium that stores various programs and control programs.

[0049] The motor drive circuit unit 120 drives a motor under the control of the control unit 110 , thereby driving the roll paper drive unit 130 . The roll paper drive unit 130 rotates the roll paper in the forward or reverse direction and is, for example, a roll paper rotation motor. The motor drive circuit unit 140 drives the motor under the control of the control unit 110 to drive the transport drive unit 150 . The transport drive unit 150 drives the transport unit 160 . The conveying section 160 is a conveying means for conveying the paper, and is, for example, a pair of conveying rollers 6.

[0050] Next, a configuration example of an arm as a support member and an example of a tip end detection operation will be described. 7A and 7B are diagrams illustrating an example of the configuration of an arm according to one embodiment, in which (A) is a perspective view illustrating an example of an arm 91, (B) is a schematic diagram illustrating the appearance of a sensor 93, and (C) is a side view illustrating an example of an actuator and a side plate that constitute the sensor 93.

[0051] The arm 91 is positioned so that the roller 92 is on the upstream side in the paper transport direction and the sensor 93 is on the downstream side when the sensor 93 detects the leading edge of the roll paper (reverse rotation).

[0052] The sensor 93 is, for example, an encoder sensor having a slit 932 provided in an actuator 931. The sensor 93 may also be called a paper thickness sensor, a leading edge detection sensor, or the like. Actuator 931 is disposed between two side plates 933 that constitute the housing of the sensor, and shaft 934 is fitted into bearings of side plates 933, so that actuator 931 rotates around shaft 934. Actuator 931 has an asymmetric shape with respect to shaft 934, for example, as shown in FIG.

[0053] Sensor 93 has a light-emitting element and a light-receiving element (not shown), and detects the leading edge of roll paper Pr by counting the number of times light passes from the light-emitting element to the light-receiving element (by counting the number of signal waveforms) through slit 932 in actuator 931. Sensor 93 has a resolution of, for example, about 5 μm / pulse, and is therefore able to detect steps equivalent to the thickness of the paper.

[0054] In the configuration example shown in Figure 7, two rollers 92 are provided, and a sensor 93 is placed between the two rollers 92. By placing the sensor 93 between the rollers 92, it is possible to reliably press down on any floating leading edge of the roll paper, and the output of the sensor 93 does not become unstable depending on the thickness, stiffness, or curl of the paper, so the leading edge can be reliably detected. Also, because the rollers 92 and the sensor 93 are positioned with a circumferential offset, even if there is a partial scratch, the proportion that it will affect both the rollers and the sensor is reduced, making it less likely to cause false detections. In the following description, the two or more rollers 92 will also be referred to as a roller portion.

[0055] Fig. 8 is a diagram illustrating an example of operation for detecting the leading edge of roll paper, and Fig. 9 is a diagram illustrating the difference depending on the positional relationship between the roller and the sensor. Figure 8 shows the process by which the leading edge of the roll paper Pr passes between roller 92 and sensor 93, with (A) showing the state before the leading edge passes roller 92, (B) showing the state after the leading edge passes roller 92 and before passing sensor 93, and (C) showing the state after the leading edge has passed sensor 93. 9A and 9B show the difference in the occurrence of slack in the leading edge detection operation when the roller 92 is downstream of the sensor 93 and when the roller 92 is upstream of the sensor 93, respectively.

[0056] The sensor 93 and roller 92 are positioned adjacent to each other but offset (offset in the circumferential direction of the roll paper), and because roller 92 is located upstream of sensor 93, roller 92 can hold down the leading edge of the paper until just before sensor 93 detects the leading edge (Figure 9(A)). In this way, as shown in Figure 9(B), sensor 93 can detect any unevenness in the surface of the roll paper (paper thickness) as the leading edge with the leading edge in close contact with the surface of roll paper Pr. This prevents the output (detection result) of sensor 93 from becoming unstable due to paper thickness, stiffness, or curl, and allows sensor 93 to reliably detect the leading edge of roll paper Pr.

[0057] In this embodiment, roller 92 is positioned upstream of sensor 93, but detection is also possible in the opposite position (FIG. 9(A)). However, positioning roller 92 upstream of sensor 93 is preferable because it makes it possible to more reliably prevent the leading edge of the roll paper from floating until just before detection. Furthermore, by providing two rollers 92 and placing a sensor between the rollers as shown in FIG. 7, it is possible to more reliably prevent the leading edge of the roll paper from floating than with a single roller 92.

[0058] Next, an example of a signal obtained by the sensor 93 will be described. Fig. 10(A) is a diagram illustrating the positional relationship between roller 92 and sensor 93, arm 91 on which roller 92 and sensor 93 are arranged, and roll paper leading edge Prs, etc. Fig. 10(B) is an example of a signal waveform obtained by sensor 93 in Fig. 10(A).

[0059] 4, 8, etc., the example shown in Figure 10(A) is similar to Figures 4, 8, etc., in that the roller 92 and the sensor 93 are positioned at different positions in the circumferential direction of the roll paper Pr, and the roller 92 and the sensor 93 are offset from each other in the circumferential direction. Also, O in the figure represents the axial center of the spool, and the sensor 93 and roller 92 are positioned toward the axial center of the spool. Also, in the leading edge detection operation, the roller 92 is positioned upstream of the sensor 93.

[0060] In the diagram, (1) to (3) are areas divided by the position of the leading edge of the roll paper Prs. (1) is the area when the leading edge of the roll paper Prs is upstream of the roller 92. (2) is the area when the leading edge of the roll paper Prs is downstream of the roller 92 and upstream of the sensor 93. (3) is the area when the leading edge of the roll paper Prs is downstream of the sensor 93. These are also referred to as area (1), area (2), and area (3).

[0061] As shown in Figure 10(B), the sensor signal value changes when the leading edge of the roll paper Prs moves from area (1) to area (2), and the sensor signal value changes when the leading edge of the roll paper Prs moves from area (2) to area (3). In the example shown here, the sensor signal value in area (1) and the sensor signal value in area (3) are the same or close to each other.

[0062] Next, we will use Figure 11 to provide additional explanation of why the signal waveform shown in Figure 10(B) is obtained. Figure 11 is a diagram illustrating an example of the movement of the roller 92, sensor 93, and arm 91 when the position of the roll paper leading edge Prs changes in the example shown in Figure 10(A). Figure 11(A) is an example of the case where the roll paper leading edge Prs moves through region (1), just like Figure 10(A). In region (1), the sensor signal does not change and remains constant, or approximately constant.

[0063] FIG. 11B shows an example where the leading edge of the roll paper Prs moves through region (2). When the leading edge of the roll paper Prs passes region (1), in other words, when the leading edge of the roll paper Prs passes the roller 92, the arm 91 rotates toward the roll paper Prs by an amount equal to the thickness of the roll paper Prs. This is indicated schematically by the white arrow in the figure. As the arm 91 rotates toward the roll paper Prs, the distance between the arm 91 and the roll paper Prs decreases, and the sensor 93 changes by the amount of this decrease. This is indicated schematically by the black arrow in the figure. This change in the sensor 93 can be expressed as a decrease in the distance between the base of the sensor 93 (the circular part in the figure) and the roll paper Prs, or as a change (smaller angle) in the angle of the sensor's detection part (the L-shaped part in the figure). Therefore, in region (2), the sensor signal decreases, as shown in FIG. 10B. However, depending on the type of sensor, the signal waveform may increase. Furthermore, when the rotation of the arm 91 stops in region (2), the signal from the sensor remains constant or approximately constant until it reaches region (3).

[0064] FIG. 11C shows an example where the leading edge of the roll paper Prs moves through region (3). When the leading edge of the roll paper Prs passes region (2), in other words, when the leading edge of the roll paper Prs passes the sensor 93, the angle of the sensor's detection portion (the L-shaped portion in the figure) increases by the thickness of the roll paper Prs. This is indicated schematically by the black arrow in the figure. In region (3), the arm 91 does not rotate, so the distance between the base of the sensor 93 (the circular portion in the figure) and the roll paper Prs does not change. The sensor 93 in region (3) has the same shape as the sensor 93 in region (1). Alternatively, it can be expressed as the distance between the roll paper Prs and the sensor 93 being the same in region (1) and region (3). Therefore, in region (3), as shown in FIG. 10B, the sensor signal becomes the same value as in region (1), or close to it.

[0065] Next, the signal waveform of the sensor in FIG. 10(B) will be described in detail. Figure 12 is a diagram showing the sensor signal waveform in Figure 10(B) so that the boundaries between regions (1) to (3) can be seen. As shown in Figure 12, it can be seen that the sensor signal has a slope at the boundary between regions (1) and (2) and the boundary between regions (2) and (3). As shown in the figure, at the boundaries between the regions, the sensor signal does not change discontinuously, but changes continuously.

[0066] In this embodiment, the presence or absence of the leading edge of the roll paper can be detected by detecting the slope K1 of the sensor signal when the leading edge of the roll paper passes roller 92, and the slope K2 of the sensor signal when the leading edge of the roll paper passes sensor 93. In other words, in accordance with Figure 12, the leading edge of the roll paper can be detected by detecting the slope K1 of the sensor signal when the leading edge of the roll paper Prs moves from area (1) to area (2), and the slope K2 of the sensor signal when the leading edge of the roll paper Prs moves from area (2) to area (3).

[0067] Here, the slope of the sensor signal when the leading edge of the roll paper passes roller 92 is referred to as slope K1, and the slope of the sensor signal when the leading edge of the roll paper passes sensor 93 is referred to as slope K2. As will be described later, in the example shown here, slope K1 is a negative value and slope K2 is a positive value, but this is not limited to this and the opposite is also possible. Depending on the type of sensor, slope K1 may be a positive value and slope K2 a negative value.

[0068] Next, we will use Figures 13 to 15 to provide additional explanation about the slope of the sensor signal in the sensor signal waveform shown in Figure 12. Figures 13(a) to 13(d) are time-series diagrams of the roll paper leading edge Prs moving from the point indicated by dashed line A in Figure 11(A), i.e., the position of roller 92, to the position shown in Figure 11(B). In other words, these diagrams show the case where the roll paper leading edge Prs reaches the end of region (1) and then moves to region (2).

[0069] As shown in Figures 13(a) to 13(d), when the leading edge of the roll paper Prs passes the roller 92, the distance between the roll paper Prs and the roller 92 gradually changes as the roller 92 rotates. As the leading edge of the roll paper Prs passes the roller 92, it moves from Figure 13(a) to, for example, Figures 13(b) and 13(c) and then to Figure 13(d). As a result, the arm 91 rotates from Figure 13(a) to, for example, Figures 13(b) and 13(c) and then to Figure 13(d). The movement of the roller 92 and arm 91 is shown schematically by white arrows.

[0070] The movement of the sensor 93 at this time is shown in Figures 14(a) to 14(d). Figures 14(a) to 14(d) correspond to Figures 13(a) to 13(d) and represent the same time series. As the arm 91 moves as shown in Figures 13(a) to 13(d), the sensor 93 gradually changes, for example, from Figure 14(a) to Figures 14(b) and 14(c) and then to Figure 14(d). For example, this can be expressed as the distance between the base of the sensor 93 (the circular part in the figure) and the roll paper Pr gradually decreasing, or as the angle of the sensor's detection part (the L-shaped part in the figure) gradually decreasing. Therefore, when the leading edge of the roll paper Prs passes the roller 92, the sensor signal has a slope K1, as shown in Figure 12.

[0071] Figures 15(e) to (h) are time-series diagrams showing the state when the leading edge of the roll paper Prs reaches the point indicated by dashed line B in Figure 11(B), i.e., the position of sensor 93, and then moves to the position shown in Figure 11(C). In other words, these diagrams show the state when the leading edge of the roll paper Prs reaches the end of region (2) and then moves to region (3). Figure 15(e) is a diagram showing the state after a time period shown in Figure 14(d).

[0072] Note that the position of dashed line B in Fig. 11 is slightly different from the position of dashed line B in Fig. 15, but this does not affect the results in any way. Dashed line B in Fig. 11 is a straight line that passes through the contact point of sensor 93 when roll paper leading edge Prs is located in area (1), and dashed line B in Fig. 15 is a straight line that passes through the contact point of sensor 93 when roll paper leading edge Prs is located in area (2).

[0073] As shown in Figures 15(e) to (h), when the leading edge of the roll paper Prs passes the sensor 93, the sensor 93 gradually changes from Figure 15(e) to Figure 15(f) and Figure 15(g), for example, and then to Figure 15(h). As a result, when the leading edge of the roll paper Prs passes the sensor 93, the sensor signal has a slope K2, as shown in Figure 12. In this embodiment, the sensor 93 has the detection accuracy to detect the step at the leading edge of the roll paper, and so it is possible to detect the slopes K1 and K2.

[0074] Next, the sensor signals shown in FIG. 12 will be described in detail with reference to FIG. FIG. 16 is a diagram with explanations of FIG. 12. In the example shown in FIG. 16, when the leading edge of the roll paper Prs passes the roller 92, the sensor signal changes from point a1 to point a4. At this time, the slope K1 can be calculated by selecting any point between point a1 and point a4, points a2 and a3. For example, if the horizontal axis of FIG. 16 is x and the vertical axis is y, and there is a change of x1 and then y1 from point a2 to point a3, the slope K1 is calculated as K1 = y1 / x1, and the slope K1 can be calculated. Although not particularly limited, the slope may be detected when the value of slope K1 is within a predetermined range. Alternatively, multiple points may be selected to calculate multiple slopes and calculate the average.

[0075] In the example shown in Figure 16, when the leading edge of the roll paper Prs passes the sensor 93, the sensor signal changes from point b1 to point b4. At this time, the slope K2 can be calculated by selecting two points, b2 and b3, between points b1 and b4. For example, if the horizontal axis in Figure 16 is x and the vertical axis is y, and the slope changes by x2 and y2 from point b2 to point b3, the slope K2 is calculated as K2 = y2 / x2, and the slope K2 can be calculated. As with the above, although not particularly limited, the slope may be detected if the value of slope K2 is within a predetermined range. Alternatively, multiple points may be selected to calculate the average of multiple slopes. In the example shown in Figure 16, the signs of slope K1 and slope K2 are reversed.

[0076] In this way, the presence or absence of the leading edge of the roll paper can be detected by detecting the slope K1 of the sensor signal when the leading edge of the roll paper passes roller 92, and the slope K2 of the sensor signal when the leading edge of the roll paper passes sensor 93. Furthermore, in this embodiment, by detecting both slope K1 and slope K2, the accuracy of detecting the presence or absence of the leading edge of the roll paper can be improved.

[0077] 16, it is preferable that the slope K1 of the sensor signal when the leading edge of the roll paper passes roller 92 and the slope K2 of the sensor signal when the leading edge of the roll paper passes sensor 93 are detected within a predetermined time T1. In this case, false detection due to unevenness on the surface of the roll paper can be suppressed.

[0078] T1 can be selected as appropriate, but is preferably as follows. When the circumferential distance from the roller 92 to the sensor 93 is L (mm), the linear velocity of the leading edge of the roll paper is V (mm / s), and the set margin time is m1 (s), T1 is calculated as follows: T1=L / V+m1 [s] This makes it possible to prevent false detections due to unevenness on the surface of the roll paper, and also to prevent the leading edge of the roll paper from being missed.

[0079] Furthermore, if the leading edge of the roll paper is not detected even after the roll paper or spool has rotated once since the start of the roll paper leading edge detection operation, it is preferable to rotate the roll paper or spool again and repeat the detection operation. This can further improve detection accuracy. In this case, it is also preferable to set the number of times the operation is performed. By setting the number of times the operation is performed, it is possible to avoid a situation where the detection operation is repeated and never completed.

[0080] As shown in the above formula, T1 can be set arbitrarily. The set margin time m1 (s) is not particularly limited and can be set as appropriate. For example, it may be set taking into consideration the type of sensor, the thickness of the roll paper, etc. However, m1 <T1である。

[0081] In this embodiment, the presence or absence of the leading edge of the roll paper is determined, for example, by the control unit 110. As will be described later, it is also possible to detect not only the presence or absence of the leading edge of the roll paper, but also the position of the leading edge of the roll paper. In this case, the position of the leading edge of the roll paper is the position in the circumferential direction of the roll paper.

[0082] In the above detection example, it was determined that the leading edge of the roll paper was present if the tilt K1 and tilt K2 were detected within a predetermined time T1, but the present invention is not limited to this.As will be explained below, by rotating the roll paper or spool multiple times and repeating the detection operation, it is possible to determine that the leading edge of the roll paper is present when the tilt K1 or tilt K2 is detected on the (n+1)th rotation, even if the tilt K1 or tilt K2 on the nth rotation cannot be detected.

[0083] The details of the sensor signal shown in Figure 12 will be further explained using Figure 17. Figure 17 shows an example where the roll paper or spool is rotated multiple times and the detection operation is repeated. Here, the signal waveforms for the nth rotation and the (n+1)th rotation are shown. n is an integer greater than or equal to 1, for example, 1.

[0084] In the above detection example, if tilt K1 and tilt K2 were detected within time T1 at the nth rotation, it was determined that the leading edge of the roll paper was present. For example, if two or more rollers 92 are arranged in the roll axial direction as shown in Figure 7, it may be difficult to detect tilt K1 and tilt K2 if the leading edge of the paper is cut at an angle.

[0085] Therefore, in this example, after detecting tilt K1 and tilt K2, it can be determined whether tilt K1 is detected again within a predetermined time T2, and if tilt K1 is detected again, it can be determined that the leading edge of the roll paper is present. This can further improve detection accuracy. The predetermined time T2 (s) is the time it takes for the roll paper or spool to make one rotation plus a set margin time m2 (s). Essentially, if tilt K1 is detected on the nth rotation, it is determined whether tilt K1 will be detected on the next (n+1)th rotation.

[0086] Similarly, after detecting tilt K1 and tilt K2, it may be determined whether tilt K2 is detected again within a predetermined time T2, and if tilt K2 is detected again, it may be determined that the leading edge of the roll paper is present. This can further improve detection accuracy. If tilt K1 is difficult to detect, it is preferable to detect tilt K2 and then determine whether tilt K2 is detected again within the predetermined time T2.

[0087] In particular, it is more preferable to repeat the detection of the slope K1 and the slope K2 multiple times, and then determine whether the slope K1 or the slope K2 is detected again within a predetermined time T2, which can further improve the detection accuracy.

[0088] These examples are for carrying out the processes of S21 to S25, S28 and S29 in the flow of FIG. 19, which will be described later.

[0089] The set margin time m2 (s) is not particularly limited and can be selected appropriately. As with the above m1, it may be set taking into consideration the thickness of the roll paper, the type of sensor, etc. However, m2 <T2である。

[0090] When a tilt K1 is detected at the nth rotation, the following is a supplementary explanation regarding the determination of whether the same tilt K1 is detected at the next n+1th rotation. For example, when a tilt is detected at the nth rotation, it may be determined that the tilt K1 has been detected if the tilt is equal to or greater than a predetermined value. Similarly, when a tilt is detected at the n+1th rotation, it may be determined that the tilt K1 has been detected if the tilt is equal to or greater than a predetermined value. The predetermined value may be selected as appropriate, but for example, it may be determined that the tilt K1 has been detected if the absolute value of the detected tilt is 4 or greater. After the tilt K1 is detected, it may be determined that the tilt K1 has been detected again within a predetermined time T2. The same applies to the tilt K2; it may be determined that the tilt K2 has been detected if the absolute value of the detected tilt is equal to or greater than a predetermined value. Note that, before determining the absolute value of the tilt K2, the sign of the tilt is checked to determine that it is different from the tilt K1.

[0091] After detecting the inclination K1, in addition to the above, it is also possible to determine whether the inclination K1 is detected again within a predetermined time T2 by considering the ratio of inclinations. When the inclination K1 at the nth rotation is K1(n) and the inclination K1 at the (n + 1)th rotation is K1(n + 1), K1(n) and K1(n + 1) do not necessarily exactly match. If the ratio between the two is within a predetermined range, it can be said that the inclination K1 is detected again within the predetermined time T2 after the inclination K1 is detected. Although it is difficult to simply say, for example, when K1(n) ≥ K1(n + 1) and K1(n) / K1(n + 1) is 1.0 or more and 1.2 or less, it can be said that the two match. When K1(n) < K1(n + 1) and K1(n) / K1(n + 1) is 0.8 or more and less than 1.0, it can be said that the two match. The same applies to the inclination K2. When K2(n) ≥ K2(n + 1) and K2(n) / K2(n + 1) is 1.0 or more and 1.2 or less, it can be said that the two match. When K2(n) < K2(n + 1) and K2(n) / K2(n + 1) is 0.8 or more and less than 1.0, it can be said that the two match.

[0092] In the present invention, it is also possible to determine whether there is a leading end of the roll paper by detecting only the inclination K2. In this case, the inclination K2 of the sensor signal when the leading end of the roll paper passes through the sensor 93 is detected, and when the inclination K2 is detected at the nth rotation of the roll paper or the spool, it is determined whether the inclination K2 is detected again at the (n + 1)th rotation. When the inclination K2 is continuously detected for a predetermined number of rotations, it is determined that there is a leading end of the roll paper. By doing so, even when it is difficult to detect the inclination K1, the leading end of the roll paper can be detected. The predetermined number of rotations can be appropriately selected.

[0093] Also, for example, when two or more rollers 92 are arranged in the roll axis direction as shown in FIG. 7, if the leading end of the paper is cut obliquely, it may be difficult to detect the inclination K1. In this case, after repeating the detection operations of the inclination K1 and the inclination K2 a predetermined number of times, the detection accuracy can be improved by detecting only the inclination K2.

[0094] The inventors investigated whether unevenness that is not the leading edge of roll paper might be mistakenly detected as the leading edge when determining the leading edge of roll paper based solely on inclination K2. When unevenness that is not the leading edge of roll paper is mistakenly detected as the leading edge, it occurs when the unevenness is sharp and its position coincides with the sensor actuator position. Such unevenness would occur, for example, when the roll paper is struck against the corner of an object. If the unevenness is not sharp, it will not be detected as inclination K2. Furthermore, because the slope of the unevenness is smaller than the shape of the curved portion of the sensor actuator, the slope of the sensor signal is small and it is not detected as the leading edge. Therefore, even when determining the leading edge of roll paper based solely on inclination K2, it is believed that false detection will be unlikely or unlikely to occur.

[0095] Next, an example of the process from setting roll paper to performing paper transport operation will be described using an example flowchart. Figure 18 is a flowchart that explains an example of the operation of setting roll paper in a paper feed device of one embodiment.

[0096] When the control unit 110 detects that roll paper Pr has been set in the paper feeder (for example, by the detection results of sensor 93) (S11), it controls the motor drive circuit unit 120 and controls the roll paper drive unit 130 to reverse the rotation of the roll paper Pr. The roll paper rotation motor (roll paper drive unit 130) rotates the roll paper Pr in the rewinding direction (S12), and the sensor 93 performs a leading edge detection operation (S13).

[0097] A in the diagram refers to the processing performed in the leading edge detection operation in S13. In the leading edge detection operation in S13, flow A shown in Figure 19 is performed. Flow A is divided into two cases: when the leading edge of the roll paper is detected (S14), and when it moves on to flow E. Flow E is shown in Figure 20. Flow E is divided into two cases: when the leading edge of the roll paper is detected (S14), and when the leading edge of the roll paper is not detected (S18).

[0098] When the leading edge is detected by sensor 93 (S14), motor drive circuit 120, under the control of control unit 110, stops the roll paper rotation motor at the paper leading edge stop position (S15) and sends the leading edge of the roll paper in the paper transport direction by rotating it forward (S16). Motor drive circuit 140 rotates transport unit 160 to transport the leading edge of the paper into the device (S17).

[0099] If the leading edge of the roll paper is not detected in flow E (S18), the roll paper rotation motor is stopped (S19). After that, if necessary, a warning is displayed on the display unit or other processing is performed.

[0100] Next, the flowchart of part A in Fig. 18 will be described with reference to Fig. 19. The example of the flowchart of part A shown in Fig. 19 is for performing the leading edge detection operation (S13). First, the leading edge detection count N is set to 0 (S21). Next, it is determined whether or not tilt K1 has been detected (S22). If tilt K1 has been detected (YES in S22), it is determined whether or not tilt K2 has been detected within T1 (S23). If tilt K2 has been detected within T1 from tilt K1 (YES in S23), the leading edge detection count (N) is incremented by 1 (S24). Regarding the determination as to whether the tilt K2 is detected within T1, for example, the content explained in Fig. 16 can be used. Also, S22 may be referred to as determining whether the sensor displacement output (K1) is detected.

[0101] Next, it is determined whether the number of times the leading edge has been detected is equal to or greater than a set value a (S25). The set value a is a value that sets how many times it takes to determine that the leading edge has been detected. The set value a is an integer equal to or greater than 1, and is increased if it is desired to increase the reliability of the detection operation. Note that FIG. 21 provides an explanation of the terms used in the flowchart.

[0102] When the number of leading-edge detections is equal to or greater than the set value a (when S25 is YES), it is determined that the leading edge of the roll paper has been detected. In other words, it is determined that there is a leading edge of the roll paper (S14). Next, the process proceeds to this flow shown in FIG. 18. Note that in FIG. 19, S14 is displayed, and S14 is also displayed in FIG. 18. Although there is overlap between the two, this is merely for ease of understanding.

[0103] To explain the above-described content again, when the set value a is 1, after detecting the inclination K1, since the inclination K2 was detected within T1, this is an example in which it was determined that there is a leading edge of the roll paper (S21 to S25, S14).

[0104] In S25, when N < a (when the number of leading-edge detections N < the set value a), that is, when S25 is NO, the leading-edge detection operation is continued (S28, S29). At this time, in this example, S28 and S29 are performed as shown in FIG. 19. In S28, after detecting the inclination K1, it is determined whether the inclination K1 is detected again within T2. As explained in FIG. 17 above, it determines whether the inclination K1 is detected again within T2, and the detection accuracy can be improved.

[0105] In S28, when the inclination K1 is detected again within T2 (when S28 is YES), after detecting the inclination K1, it is determined whether the inclination K2 is detected within T1 (S29). When S29 is YES, the process returns to S24, and the number of leading-edge detections (N) is incremented by 1. Again, the determination in S25 is performed. When it is YES, it is determined that there is a leading edge, and the process returns to this flow. Thus, by performing S25, S28, and S29, the detection accuracy can be further improved.

[0106] In S22 of FIG. 19, when the inclination K1 is not detected (when S22 is NO), it is determined whether there is an output from the sensor (S26). When there is no output from the sensor (when S26 is NO), it is determined that the sensor is malfunctioning (sensor abnormality) (S27).

[0107] In the determination of S26, for example, it is determined whether there is a sensor output for a predetermined time. The predetermined time is preferably, for example, the time it takes for the roll paper or spool to make one rotation or longer. This can reduce false detections.

[0108] If the determination in S26 is YES, that is, if tilt K1 was not detected and there was a sensor output, the number of rotations of the roll paper is determined (S30). Here, it is determined whether it has rotated R times. As shown in FIG. 21, R is a value that sets the number of times the roll paper must rotate before the leading edge is detected. Note that although the number of rotations of the roll paper is determined, the number of rotations of the spool can also be determined. If the number of rotations of the roll paper is less than R times (if the determination in S30 is NO), the number of rotations is counted up (S31), and it is then determined again whether tilt K1 has been detected (S22).

[0109] In the processing flow of S22, S26, and S30, tilt K1 is not detected, but there is sensor output, so it is assumed that the sensor is not faulty. Since tilt K1 has not been detected for some reason, the roll paper is repeatedly rotated in an attempt to detect tilt K1. By performing this process multiple times, it is possible to reduce the chance of missing the leading edge of the roll paper when it is actually there.

[0110] If the roll rotation count is R (YES in S30), the process proceeds to flow E shown in Fig. 20. Also, if the determinations in S28 and S29 are NO, in other words, if the slopes K1 and K2 are not detected, the process proceeds to flow E shown in Fig. 20 after making the determination in S30. Flow E is the process to which the process proceeds if the leading edge of the roll paper is not detected in flow A.

[0111] FIG. 20 is a flowchart showing an example of flow E. First, the leading edge detection count N is set to 0 (S41). Next, it is determined whether or not the tilt K2 has been detected (S42). In S42, it may be referred to as determining whether or not the sensor displacement output (K2) has been detected.

[0112] If tilt K2 is detected (if S42 returns YES), the leading edge detection count (N) is incremented by 1 (S43). Next, it is determined whether the leading edge detection count is equal to or greater than set value a (S44). Set value a is the same as above, and is a value that sets how many times it is determined to be the leading edge. If the leading edge detection count is equal to or greater than set value a (if S44 returns YES), it is determined that the leading edge of the roll paper has been detected; in other words, it is determined that the leading edge of the roll paper is present (S14). Next, the process moves to the main flow shown in Figure 18. Note that S14 is shown in Figure 20 and also in Figure 18, so there is duplication in both, but it is simply displayed that way for ease of understanding.

[0113] In S44, it is preferable to set the setting value a to 2 or greater, and to perform the process of S46 at least once. In other words, it is preferable to determine whether tilt K2 has been detected over multiple rotations. In the determination of S44, when tilt K2 has been detected over the nth rotation of the roll paper or spool, it is preferable to determine whether tilt K2 has been detected again over the n+1th rotation, and to determine that the leading edge of the roll paper is present if tilt K2 has been detected consecutively for a predetermined number of rotations. In this case, the leading edge of the roll paper can be detected with greater accuracy. For example, it is possible to prevent irregularities that are not the leading edge of the roll paper from being mistakenly identified as tilt K2.

[0114] In S46, after detecting the tilt K2, it is determined whether the tilt K2 is detected again within T2. ​​This means that when the tilt K2 is detected at the nth rotation, it is determined whether the tilt K2 is detected again at the n+1th rotation (see FIG. 17).

[0115] If the determination in S42 is NO, i.e., if tilt K2 was not detected, the number of rotations of the roll paper is determined (S45). Here, it is determined whether the roll paper has rotated R times, where R is the same as above. If the number of rotations of the roll paper is less than R times (if the determination in S45 is NO), the number of rotations is counted up (S31), and it is again determined whether tilt K2 was detected (S42).

[0116] If the number of roll rotations is R or more (YES in S45), it is determined that the leading edge of the roll paper is not there, and the roll paper rotation motor is turned off (S18, S19). Note that S18 and S19 are shown in Figure 20, and S18 and S19 are also shown in Figure 18, so they are duplicated in both, but are shown that way simply for ease of understanding.

[0117] Also, if the determination in S46 is NO, in other words, if tilt K2 is not detected, after the determination in S45, it is determined that the leading edge of the roll paper is not present, and the roll paper rotation motor is turned OFF (S18, S19).

[0118] By performing steps S22, S26, and S30, and then steps S42 and S44, and preferably S46, it is possible to detect the presence or absence of the leading edge of the roll paper using only the tilt K2, even if the tilt K1 is not detected. Furthermore, by performing step S46, detection accuracy can be improved.

[0119] In this embodiment, simply by setting the spool in the holder of the paper feeder, the leading edge of the roll paper can be detected automatically and accurately. Furthermore, in this embodiment, because it is possible to determine that roll paper is set when the leading edge of the roll paper is detected, there is no need to provide a component such as a reflective sensor. Therefore, it is possible to detect whether roll paper is set without increasing the number of components.

[0120] As will be described later, this embodiment can prevent the process from being performed as if roll paper were loaded even when roll paper is not. Conventionally, the printer would detect that a spool was loaded in the holder and display a paper feed screen on the display (operation unit). If only a spool was loaded without roll paper, paper feeding would not be possible, requiring the user to close the paper feed screen. In this case, if the start paper feed button on the paper feed screen is accidentally pressed, the printer will continue to operate until it determines that paper feeding has failed. This will require the user to open the cover, stop the printer, and take action to restart the printer, increasing the burden on the operator (or user).

[0121] According to the present invention, it is possible to automatically and accurately detect that roll paper is not set without increasing the number of parts, and to prevent the process for when roll paper is set from being performed even though roll paper is not set.

[0122] Next, the rotation range of the arm 91 (support member) will be described. 22 is a diagram showing the state in which the paper roll 99 is in contact with the roller 92 and the sensor 93. When the paper wound around the paper roll 99 is used up, the roller 92 attached to the arm 91 comes into contact with the paper roll 99, and the sensor 93 also comes into contact with the paper roll 99, entering a state in which it detects the paper roll 99. In this case, the output of the sensor 93 is in a state in which it detects and outputs the unevenness of the surface of the paper roll 99.

[0123] 23 shows the state when the spool 98 is set without the roll paper Pr set on the spool 98, an example not included in the present invention. As shown in the figure, the sensor 93 comes into contact with the spool 98 and is in a state of detecting the spool. The output of the sensor 93 is in a state of detecting and outputting the unevenness of the surface of the spool 98.

[0124] FIG. 24 is a diagram showing an example of the configuration of this embodiment. Reference numeral 99a denotes the outer diameter of the cardboard tube, which is indicated by a dashed line. The arm 91 can rotate so that the roller 92 and sensor 93 face the axial center of the spool 98. The rotation range of the arm 91 is a range in which the sensor 93 does not come into contact with the spool 98. For example, even when the arm 91 is closest to the spool 98, the sensor 93 does not come into contact with the spool 98. Therefore, if only the spool 98 is set without a roll of paper, the sensor 93 not only does not come into contact with the spool 98, but also does not come into contact with anything. When the sensor 93 is not in contact with anything, the output of the sensor 93 remains constant, and the output signal does not change. This allows for accurate detection of when only the spool is set without a roll of paper.

[0125] FIG. 25 is a diagram illustrating an example of an output signal of the sensor. The output signal shown in Figure 25(a) is an example when the sensor 93 is in contact with the surface of the paper tube 99 or the surface of the spool 98. Because the surface of the paper tube 99 and the surface of the spool 98 are uneven or wavy, the signal is not constant but varies over a certain range. The range is smaller than the signal corresponding to the difference in the height of the paper.

[0126] The output signal shown in FIG. 25(b) is obtained when the sensor 93 is not in contact with anything, and therefore the sensor output is constant. The fact that the sensor output is constant may be determined, for example, by acquiring an output signal in advance when the sensor 93 is not in contact with anything and storing it in the device. To determine that the sensor output is constant, for example, a certain threshold may be set, and if the sensor output does not exceed that threshold, it may be determined that the output is constant or that the output does not change. The threshold may be set taking into account the type of sensor, etc.

[0127] In automatic paper feeding, when the spool 98 is set in a holder (for example, spool bearing pedestal 5a, 5b), a sensor (spool detection sensor) that detects that the spool 98 has been set recognizes this on the system side, and a paper feed screen is displayed on the display unit (also referred to as the operation unit, etc.). The paper feed screen displays a confirmation screen for the paper type, a paper feed start button, a paper feed cancel button, etc. The contents of the paper feed screen can be changed as needed.

[0128] When the paper feed start button is pressed, the automatic paper feed operation begins. The automatic paper feed operation includes, for example, detecting the leading edge of the roll paper and transporting the leading edge of the roll paper to the paper feed unit. Even if a spool without roll paper is placed in the holder, the feed screen appears, and the paper feed start button appears on the screen, requiring the user to cancel the operation using the cancel button or similar. There are various situations in which a spool without roll paper may be placed in the holder, such as when paper is not being fed but there is no storage space for the spool and the user wants to place it in the device.

[0129] If the paper feed start button is pressed at this time, the operation will continue until the device determines that the automatic paper feed has failed, and there will be other problems, such as the need to open the cover to stop the device. Furthermore, if the cover is opened to stop the device, the device will also need to be reset, which will increase the time and effort.

[0130] In this embodiment, the leading edge of the roll paper can be detected automatically and accurately, so for example, if the control unit determines that the leading edge is present, it can carry out the processing that would normally be performed if roll paper were set, and if it determines that the leading edge is not present, it can avoid the processing that would normally be performed if roll paper were set. This prevents the above-mentioned problems and reduces the operator's workload.

[0131] In this embodiment, it is possible to detect that a spool has been installed in the paper feeder. After detecting that a spool has been installed, the device performs an operation to detect whether or not the leading edge of the roll paper is present. If it determines that the leading edge of the roll paper is present, the display unit displays a paper feed screen for paper feeding. If it determines that the leading edge of the roll paper is absent, the display unit does not display the paper feed screen for paper feeding. This arrangement reduces the operator's workload. It also prevents the operator from accidentally pressing the paper feed start button when only the spool is installed without the roll paper. This process can be performed, for example, in S18 and S19 of FIG. 18.

[0132] Furthermore, in this embodiment, if the signal from sensor 93 remains constant within a specified time, it can be determined that no roll paper is installed and only the spool 98 is installed, or that the sensor 93 is malfunctioning. During the operation to detect the leading edge of the roll paper in automatic paper feeding, if the signal from sensor 93 remains constant (no change) within a certain time, it is determined that no roll paper is installed and only the spool is installed, or that the sensor 93 is malfunctioning. By making this determination, it is possible to prevent the paper feed screen from being displayed on the display unit, and to prevent a paper feed operation from being instructed even when paper feeding is not possible.

[0133] The predetermined time is preferably equal to or longer than the time it takes for the roll paper or spool to make one rotation, which can reduce false detections.

[0134] Figure 26 shows an example where the sensor signal is constant. The specified time is set to be equal to or longer than the time it takes for the roll paper (spool) to make one rotation, and the sensor signal is constant in the area enclosed by the dashed line. If the signal from the sensor is constant, in other words, if the sensor signal does not change, it can be determined that there is no roll paper and only the spool 98 is installed, or it can be determined that the sensor 93 is malfunctioning.

[0135] Furthermore, in the above, if the control unit determines that there is no roll paper and only the spool 98 is installed, or that the sensor 93 is malfunctioning, it is preferable that the control unit not display the paper feed screen for paper feeding, but instead display a warning on the display that there is no roll paper or that the sensor 93 is malfunctioning. In this case, if the operator is unaware that roll paper is not installed, this can be notified. It can also prevent a paper feeding operation from being instructed even when paper feeding is not possible.

[0136] Next, an example of a flow that takes the above into consideration will be described. FIG. 27 is another example of the flow of A, in other words, another example of FIG. 19. In FIG. 27, the same processes as those in FIG. 19 are given the same step names. Here, differences from FIG. 19 will be mainly explained. As with FIG. 19 etc., the terms used in the flow are explained in FIG. 21.

[0137] 19, in this example, after determining whether tilt K1 has been detected, it is determined whether there is a sensor output (S22, S26). In this example, if there is no sensor output (NO in S26), it is determined whether the roll paper has rotated S1 times (S51). If the roll paper has rotated S times (YES in S51), it is determined that only the spool has been set or that there is a sensor abnormality (S52).

[0138] Although the rotation speed of the roll paper is determined here, the invention is not limited to this and the rotation speed of the spool may also be determined.

[0139] If S51 is YES, the drive system is stopped and a warning screen is displayed as necessary (S53). In this example, a message is displayed indicating that either only the spool has been set or that there is a sensor abnormality. If the output of sensor 93 is constant, it is possible that either only the spool has been set (a spool without roll paper has been set) or that the sensor 93 has failed, so in this example, a message such as "Only the spool has been set or the sensor has failed" is displayed.

[0140] If the sensor signal is not constant (NO in S26), the same determination as in S30 above is made, and if the roll paper has rotated R times (YES in S30), the same flow E as above is carried out. Flow E and the processing from S23 onwards are the same as above, so a description thereof will be omitted here.

[0141] This example prevents the paper feed screen from appearing when an abnormality occurs in the device or when roll paper is not installed. This eliminates the need to take action when the paper feed screen appears, preventing the operator from having to take time and effort. This can also be done without adding any additional components for detection.

[0142] As mentioned above, when only a spool is set (when a spool without roll paper is set) and when the sensor 93 is broken, no signal is output (the signal is constant), so it is not possible to distinguish between these two cases. Therefore, it is possible to determine whether the sensor is broken, for example, as follows.

[0143] In the following description, the sensor that detects that a spool is provided will be referred to as a spool detection sensor, and the sensor 93 disposed on the arm 91 will be referred to as a tip detection sensor. The spool detection sensor can be provided, for example, on the spool bearing pedestals 5a and 5b in FIG. 1.

[0144] In this example, the control unit stores in advance, as a preliminary operation, an operation in which the spool detection sensor detects that the spool has been installed and the leading edge detection sensor does not output any signal even after the spool has been rotated for a predetermined time. The control unit then determines that the leading edge detection sensor is malfunctioning if the spool detection sensor and the leading edge detection sensor behave in the same manner as in the preliminary operation and this behavior occurs a predetermined number of times in succession. This makes it possible to determine whether a sensor is malfunctioning. In addition to malfunctions of the leading edge detection sensor (sensor 93), this example can also detect improper installation of the sensor connector. The operation of each sensor in the preliminary operation is stored in a storage unit, for example.

[0145] Figure 28 is a flow for explaining this example, and is a flow that performs processing in a different chronological order from S51 in Figure 27. In S51 in Figure 27, if there is no output from sensor 93, it is determined whether the roll paper has made S rotations, and if the roll paper has made S rotations, it is determined that only the spool has been set or that the sensor is faulty (S52). In this example, a determination in S54 is made separately from, for example in parallel with, the processing of S52.

[0146] In S54, it is determined whether the spool detection sensor and the leading edge detection sensor have performed the same operation as the previous operation a predetermined number of times NS in succession. If S54 is YES, it is determined that there is a sensor abnormality (S55), the drive system is stopped, and a warning screen is displayed as necessary (S53). In this example, the warning screen displayed may indicate, for example, that the sensor is broken. This makes it easier for the operator or user to respond.

[0147] Here, we will provide additional explanation of the preliminary operation. The preliminary operation is an operation in which the spool detection sensor detects that the spool has been set in the device, and even if the spool is rotated for a predetermined time, there is no output from the leading edge detection sensor. In the preliminary operation, an operation in which there is no output from the leading edge detection sensor can be performed, for example, by using a faulty leading edge detection sensor. The predetermined time here can be, for example, a time longer than the time it takes for the spool to rotate once.

[0148] When the spool detection sensor and leading edge detection sensor behave in the same way as in the previous operation, the number of times this has occurred is recorded. This number is compared with a predetermined number of times NS, and if this occurs the predetermined number of times NS in succession, it is determined that the leading edge detection sensor is faulty.

[0149] The reason for determining whether an error has occurred a predetermined number of times NS in S54 is that if there is an output from the leading edge detection sensor even once (if the output signal is not constant even once), it is determined that the leading edge detection sensor is not malfunctioning. In this case, the count is cleared after the determination process of S26 (sensor output determination). One example of a case in which there is an output from the leading edge detection sensor even once would be when roll paper is set.

[0150] An actual detection example will be given below for further explanation, but it is not limited to the following example. For example, the first time, a spool without roll paper is set in the device. At this time, an output is generated from the spool detection sensor. Next, suppose that the leading edge detection sensor does not generate an output (the signal remains constant) even after the spool is rotated for a predetermined time. This operation is considered to be the same as the previous operation, and the count is incremented by one. In this case, the determination in S51 of FIG. 27 may be made in parallel, and a warning screen may be displayed indicating that only the spool has been set or that the sensor has failed. For the second time, the first spool is reset. This causes an output from the spool detection sensor. Next, assume that the spool is rotated for a predetermined time, but no output is generated from the tip detection sensor (the signal remains constant). This operation is considered to be the same as the previous operation, and the count is incremented by one. If the NS number of times is 2, the determination in S54 will be YES, it will be determined that there is a sensor abnormality, and a warning to that effect will be displayed. In this way, it is possible to detect a sensor abnormality. In this example, the presence or absence of an output from the spool detection sensor is determined, for example, by roll paper setting detection (S11) in FIG.

[0151] As an example of clearing the count, for example, the first time, the count is incremented by setting a spool without roll paper, and the second time, the count is cleared when a spool with roll paper set is set and an output from the leading edge detection sensor is detected. [Explanation of symbols]

[0152] 6 Transport roller pair 90, 90A paper feeder 91, 91A Arm 92 Coro 93 Sensors 95 Entrance guide plate 97 Support member 98 spools 99 Paper tube 100, 110 control section 120, 140 Motor drive circuit section 130 Roll paper drive unit 150 Conveyor drive unit 160 Conveyor 911 Rotation center 931 Actuator 932 Slit 933 Side Panel 934 Axis [Prior art documents] [Patent documents]

[0153] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-150107 [Patent Document 2] Patent Publication No. 2021-113118

Claims

1. A paper feeder that supplies long sheets of paper from a roll of paper, a support member that supports a sensor and a roller portion so that the sensor and the roller portion contact the surface of the roll paper; and a control unit that acquires a signal from the sensor, The roll paper has a paper tube inside, a spool is inserted inside the paper tube, and the roll paper is provided in the paper feed device, and rotates in conjunction with the rotation of the spool, The sensor and the roller portion are disposed toward the axial center of the spool, the roller portion is disposed at a different position from the sensor in the circumferential direction of the roll paper, the sensor has a detection accuracy capable of detecting a step at the leading edge of the roll paper, the support member is rotatable and rotates within a range where the sensor does not come into contact with the spool; The control unit determines whether the leading edge of the roll paper is present by detecting the slope K1 of the sensor signal when the leading edge of the roll paper passes through the roller portion and the slope K2 of the sensor signal when the leading edge of the roll paper passes through the sensor.

2. The paper feeding device described in claim 1, characterized in that the control unit determines that the tip of the roll paper is present when a slope K1 of the sensor signal when the tip of the roll paper passes through the roller portion and a slope K2 of the sensor signal when the tip of the roll paper passes through the sensor are detected within a predetermined time T1.

3. The control unit When the tilt K1 is detected at the nth rotation of the roll paper or the spool, it is determined whether the tilt K1 is detected again at the n+1th rotation, and if the tilt K1 is detected continuously for a predetermined number of rotations, it is determined that the leading edge of the roll paper is present; or A paper feeding device as described in claim 1, characterized in that when the tilt K2 is detected at the nth rotation of the roll paper or the spool, it is determined whether the tilt K2 is detected again at the n+1th rotation, and if the tilt K2 is detected continuously for a predetermined number of rotations, it is determined that the leading edge of the roll paper is present. Here, n is an integer of 1 or more.

4. A paper feeder that supplies long sheets of paper from a roll of paper, a support member that supports a sensor and a roller portion so that the sensor and the roller portion contact the surface of the roll paper; and a control unit that acquires a signal from the sensor, The roll paper has a paper tube inside, a spool is inserted inside the paper tube, and the roll paper is provided in the paper feed device, and rotates in conjunction with the rotation of the spool, The sensor and the roller portion are disposed toward the axial center of the spool, the roller portion is disposed at a different position from the sensor in the circumferential direction of the roll paper, the sensor has a detection accuracy capable of detecting a step at the leading edge of the roll paper, the support member is rotatable and rotates within a range where the sensor does not come into contact with the spool; The control unit detects the slope K2 of the sensor signal when the leading edge of the roll paper passes the sensor, and when the slope K2 is detected on the nth rotation of the roll paper or the spool, determines whether the slope K2 is detected again on the n+1th rotation, and determines that the leading edge of the roll paper is present when the slope K2 is detected continuously for a predetermined number of rotations. Here, n is an integer of 1 or more.

5. A paper feeding device as described in any one of claims 1 to 4, characterized in that if the signal from the sensor is constant within a predetermined time, the control unit determines that the roll paper is not installed and only the spool is installed, or that the sensor is faulty.

6. 6. The paper feeding device according to claim 5, wherein the predetermined time is equal to or longer than the time it takes for the roll paper or the spool to make one rotation.

7. The paper feeding device described in claim 5 or 6, characterized in that when the control unit determines that the roll paper is not provided and only the spool is provided, or that the sensor is malfunctioning, it does not display a paper feeding screen for feeding paper on the display unit, but instead displays a warning on the display unit that the roll paper is not provided or the sensor is malfunctioning.

8. a spool detection sensor that detects that the spool has been provided; When the sensor disposed on the support member is referred to as a tip detection sensor, The control unit pre-stores an operation as a preliminary operation in which the spool detection sensor detects that the spool has been installed and there is no output from the leading edge detection sensor even when the spool is rotated for a predetermined time, and when the spool detection sensor and the leading edge detection sensor perform the same operation as the preliminary operation and this operation occurs a predetermined number of times in succession, it determines that the leading edge detection sensor is faulty.

9. The control unit is capable of detecting that the spool is installed in the paper feeding device, and after detecting that the spool is installed, performs an operation to detect whether or not the leading edge of the roll paper is present, and if it determines that the leading edge of the roll paper is present, displays a paper feeding screen on the display unit for paper feeding, and if it determines that the leading edge of the roll paper is not present, does not display the paper feeding screen for paper feeding on the display unit.

10. 10. The paper feeding device according to claim 1, wherein the support member is pressed toward the spool.

11. An image forming apparatus comprising the paper feeder according to any one of claims 1 to 10.

Images