Paper feeding device and image forming apparatus

Abstract

To provide a paper feeding device that can effectively automatically and accurately detect that a paper roll is not set on the spool and also, prevent processing for the case that the roller is set from being performed when no paper roll is set.SOLUTION: A paper feeding device includes: a support member 91 arranged with a tip detection sensor 93 and a roller part 92. A paper roll has a paper tube 99 inside and is provided in the paper feeding device with a spool 98 inserted inside the paper tube. The roller part is positioned at a different position from a sensor in a circumferential direction of the roll paper. The sensor is capable of detecting a step at the leading-end of the roll paper. The spool has a concave part or convex part on a surface thereof. The concave or convex part is provided at a position where it contacts the sensor or the roller part when the spool is provided and rotated in the paper feeding device with neither paper nor paper tube on the spool. Based on the sensor signal of the sensor, the control part detects whether or not the leading-end of the roll paper exists and whether or not the roll paper is provided on the spool.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a paper feeding device and an image forming apparatus.

Background Art

[0002] In an image forming apparatus using roll paper, it is known that after setting the roll paper on a spool and placing it on the holding part of the paper feeding device, the paper feeding device performs a paper feeding operation. In such a device, a technique for detecting the leading edge of the roll paper is known.

[0003] In Patent Document 1, for the purpose of detecting the leading edge of the roll paper, a configuration is disclosed in which the roll paper is rotated in the winding direction to peel off the paper, and a sensor (the output value changes according to the distance to the peeled paper) is used to detect the leading edge of the paper. According to Patent Document 1, it is said that the automatic paper feeding of the mounted roll can be performed more reliably.

[0004] In Patent Document 2, a paper feeding device is disclosed that includes a support member on which a sensor and a roller part are arranged, and the sensor has a detection accuracy capable of detecting a step at the leading edge of the roll paper. According to Patent Document 2, it is said that the leading edge of the roll paper can be stably detected and conveyed to the paper feeding part.

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the prior art, when a spool without roll paper is set in the paper feeding device, there are cases where the processing when the roll paper is set is performed even though the roll paper is not set. In addition to the requirement for efficient detection, an improvement in detection accuracy has been demanded.

[0006] Therefore, an object of the present invention is to provide a paper feeding device that can automatically and accurately detect with high efficiency that the roll paper is not set on the spool, and can prevent performing the processing when the roll paper is set even though the roll paper is not set. [Means for solving the problem]

[0007] To solve the above problems, the paper feeding device of the present invention is A paper feeder that supplies paper from a roll of paper in which a long sheet of paper is wound, A support member is provided which a tip detection sensor and a roller are arranged and which supports the tip detection sensor and the roller so that they contact the surface of the roll paper, The system includes a control unit that acquires the sensor signal from the aforementioned tip detection sensor, The aforementioned roll of paper has a paper core inside, and a spool is inserted inside the paper core and provided in the paper feeding device, and rotates in conjunction with the rotation of the spool, The tip detection sensor and the roller portion are arranged toward the axial center of the spool, The roller portion is positioned in a different location from the tip detection sensor in the circumferential direction of the roll paper. The aforementioned tip detection sensor is capable of detecting the step at the leading edge of the roll paper, The spool has a recess or protrusion on a part of its surface, The recess or protrusion is positioned to contact the tip detection sensor or the roller when the spool is installed in the paper feeding device and rotates without the paper and paper core on the spool. The control unit determines, based on the sensor signal from the tip detection sensor, whether or not there is a tip of the roll paper, and whether or not the roll paper is loaded onto the spool. It is characterized by the following: [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a paper feeder that can efficiently and accurately detect when a roll of paper is not set on the spool, and that can prevent the device from performing processing when a roll of paper is set, even though no roll of paper is set. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows a schematic configuration example of an image forming apparatus according to one embodiment. [Figure 2] This is a schematic cross-sectional view showing an example of the configuration of an image forming apparatus according to one embodiment. [Figure 3] This diagram illustrates a conventional method for setting roll paper. [Figure 4] This is a diagram illustrating how to set a roll of paper onto a spool. [Figure 5] This is a side view illustrating the main components of an example configuration of a paper feeding device in one embodiment. [Figure 6] This is a functional block diagram illustrating an example of the functions of a paper feed device in one embodiment. [Figure 7] This figure illustrates an example of the configuration of an arm in one embodiment. [Figure 8] This diagram illustrates an example of how the leading edge of a paper roll is detected. [Figure 9] This diagram illustrates the differences caused by the relative positions of the roller and the sensor. [Figure 10] Figure (A) shows an example of the positional relationship between the roller, sensor, and the tip of the roll paper, and Figure (B) shows an example of the waveform of the sensor signal. [Figure 11] Figures (A) to (C) illustrate an example of the movement of the roller, sensor, and arm when the position of the leading edge of the paper roll changes. [Figure 12] This figure shows an example of the waveform of the sensor signal in Figure 11. [Figure 13] Figures (a) to (d) illustrate an example of the movement of the roller and arm when the position of the leading edge of the paper roll changes. [Figure 14] Figures (a) to (d) illustrate an example of sensor movement when the position of the leading edge of the paper roll changes, as shown in Figure 13. [Figure 15] Figures (e) to (h) illustrate an example of sensor movement when the position of the leading edge of the roll paper changes further, as shown in Figure 14. [Figure 16] Figure 12 is a diagram that provides a detailed explanation of the waveform of the sensor signal shown. [Figure 17] It is a diagram for explaining an example of the waveform of a sensor signal when the detection operation is repeated. [Figure 18] It is a flowchart for explaining an example from setting the roll paper to performing the paper conveyance operation. [Figure 19] It is a flowchart for explaining part A in FIG. 18. [Figure 20] It is a flowchart for explaining part E in FIG. 19. [Figure 21] It is a diagram for explaining the symbols used in the flowcharts shown in FIGS. 19, 20, and 27. [Figure 22] It is diagrams (A) and (B) showing an example when there is no roll paper and a paper tube is set. [Figure 23] It is diagrams (A) and (B) showing an example when set in the state of an empty spool. [Figure 24] It is diagrams (A) and (B) showing another example when set in the state of an empty spool. [Figure 25] It is diagrams (A) to (C) showing an example of the positional relationship between the concavo-convex part, the roller, and the sensor. [Figure 26] It is diagrams (D) to (F) showing an example of the positional relationship between the concavo-convex part, the roller, and the sensor. [Figure 27] It is diagrams (A) and (B) showing an example of a concave part and diagrams (C) and (D) showing an example of a convex part. [Figure 28] It is a diagram showing an output example of a sensor signal when in contact with the surface of the paper tube. [Figure 29] It is a diagram for explaining an example of the movement when the roller passes through the concave part. [Figure 30] It is the contact example (A) of the roller in FIG. 29, the output example (B) of the sensor signal when the roller passes through the concave part, and the slope example (C) of the sensor signal in (B). [Figure 31] It is a diagram showing an output example of a sensor signal when detecting an empty spool, and it is a diagram showing an example when there is one concave part. <0​This figure shows an example of the sensor signal output when detecting an empty spool, specifically an example with two recesses. [Figure 33] Figure (A) shows examples of sensor signal output when detecting an empty spool, with example S1 showing the case with one recess and example S2 showing the case with the maximum usable paper thickness. Figure (B) is a diagram with supplementary explanations added to (A). [Figure 34] This figure shows an example of the sensor signal output when detecting the leading edge of a roll of paper. [Figure 35] This is an example flowchart for detecting the leading edge of a paper roll and detecting an empty spool. [Figure 36] This is another example of a flowchart for detecting the leading edge of a paper roll and detecting an empty spool. [Modes for carrying out the invention]

[0010] The paper feeding device and image forming apparatus according to the present invention will be described below with reference to the drawings. It should be noted that the present invention is not limited to the embodiments shown below, and other embodiments, additions, modifications, and deletions may be made within the scope of what a person skilled in the art can conceive. Any embodiment that achieves the function and effect of the present invention is included within the scope of the present invention.

[0011] The paper feeding device of the present invention is A paper feeder that supplies paper from a roll of paper in which a long sheet of paper is wound, A support member is provided which a tip detection sensor and a roller are arranged and which supports the tip detection sensor and the roller so that they contact the surface of the roll paper, The system includes a control unit that acquires the sensor signal from the aforementioned tip detection sensor, The aforementioned roll of paper has a paper core inside, and a spool is inserted inside the paper core and provided in the paper feeding device, and rotates in conjunction with the rotation of the spool, The tip detection sensor and the roller portion are arranged toward the axial center of the spool, The roller portion is positioned in a different location from the tip detection sensor in the circumferential direction of the roll paper. The aforementioned tip detection sensor is capable of detecting the step at the leading edge of the roll paper, The spool has a recess or protrusion on a part of its surface, The recess or protrusion is positioned to contact the tip detection sensor or the roller when the spool is installed in the paper feeding device and rotates without the paper and paper core on the spool. The control unit determines, based on the sensor signal from the tip detection sensor, whether or not there is a tip of the roll paper, and whether or not the roll paper is loaded onto the spool. It is characterized by the following:

[0012] According to the present invention, it is possible to efficiently and accurately detect automatically when a roll of paper is not set on the spool, and to prevent processing that would occur if a roll of paper were set when it is not. Efficient detection can be achieved, for example, by performing detection without increasing the number of parts.

[0013] The paper feeder of this embodiment supplies paper from a roll of paper. The roll of paper is a recording medium in which a long sheet of paper (also referred to as a "sheet") is wound into a roll.

[0014] Referring to Figures 1 and 2, an example of the configuration of an image forming apparatus to which a paper feeding device according to one embodiment of the present invention is applied will be described. One embodiment of the present invention is an inkjet printer that prints on a recording medium by ejecting ink droplets corresponding to image data. However, the present invention can also be applied to photocopiers, printers, and the like that which transport a recording medium and perform printing.

[0015] Figure 1 shows a perspective view of a schematic configuration example of an image forming apparatus 80 according to one embodiment, and Figure 2 shows a side cross-sectional view of the image forming apparatus. The operation of the main parts will be explained along with the overall configuration of the image forming apparatus according to one embodiment. In Figure 1, the arrows indicate the depth direction (front-to-back direction) of the image forming apparatus 80 (X), the width direction (main scanning direction) of the image forming apparatus 80 (Y), and the up-and-down direction (Z).

[0016] In Figure 1, the image forming apparatus 80 is a serial-type liquid ejection (ink ejection) image forming apparatus, and the main housing 81 is arranged on the main frame 82. Within the main housing 81 of the image forming apparatus 80, a main guide rod 64 and a sub-guide rod 65 are stretched in the main scanning direction indicated by the double arrow Y in Figure 1. The main guide rod 64 movably supports the carriage 66, and the carriage 66 is provided with a connecting piece 66a that engages with the sub-guide rod 65 to stabilize the posture of the carriage 66.

[0017] The image forming apparatus 80 has an endless belt-shaped timing belt 67 arranged along the 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 rotationally driven by the main scanning motor 70, and the driven pulley 69 is positioned to apply a predetermined tension to the timing belt 67. The rotational drive of the drive pulley 68 by the main scanning motor 70 causes the timing belt 67 to rotate in the main scanning direction according to its rotational direction.

[0018] The carriage 66 is connected to the timing belt 67, and as the timing belt 67 is rotated in the main scanning direction by the drive pulley 68, the carriage 66 reciprocates along the main guide rod 64 in the main scanning direction.

[0019] The image forming apparatus 80 has a cartridge unit 71 and a retention mechanism unit 72 detachably housed in the main scanning direction end of the main housing 81. The cartridge unit 71 houses replaceable cartridges 73, each containing yellow (Y), magenta (M), cyan (C), and black (K) inks. Each cartridge in the cartridge unit 71 is connected to the corresponding colored recording head of the recording head (not shown) mounted on the carriage 66 by a pipe (not shown), and ink is supplied from the cartridge unit 71 to the respective colored recording head through the pipe.

[0020] The image forming apparatus 80 records an image on the paper P by moving the carriage 66 in the main scanning direction and ejecting ink onto the paper P, which is intermittently transported on the platen 74 (see Figure 2) in a sub-scanning direction (arrow X direction in Figure 1) perpendicular to the main scanning direction.

[0021] The paper P is not limited to paper; 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 of roll paper Pr will be referred to as Ps.

[0022] As shown in Figure 2, the image forming apparatus 80 has a chamber 75 with a fan located below the platen 74. By driving the fan, the paper P being transported on the platen 74 is transported while in close contact with the platen 74.

[0023] The image forming apparatus 80 intermittently transports the paper P in the sub-scanning direction, and while the transport of the 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 row of the recording head mounted on the carriage 66 onto the paper P on the platen 74 to form (record) an image on the roll-shaped paper P.

[0024] The maintenance mechanism 72 cleans the ejection surface of the recording head, performs capping, ejects excess ink, etc., to remove excess ink from the recording head and maintain the reliability of the recording head.

[0025] The image forming apparatus 80 has an encoder sheet (not shown) arranged parallel to the timing belt 67 and the main guide rod 64, extending at least over the range of movement of the carriage 66. An encoder sensor for reading the encoder sheet is attached to the carriage 66. The image forming apparatus 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 reading result of the encoder sheet by the encoder sensor.

[0026] Furthermore, reflective sensors (encoder sensors, paper leading edge detection sensors) mounted on the carriage 66 detect 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 leading edge detection sensor.

[0027] As shown in Figures 1 and 2, the image forming apparatus 80 has two spool bearing bases 5a and 5b provided on the main frame 82 that supports the main housing 81, in the vertical direction in Figures 1 and 2.

[0028] The paper (roll-shaped paper) P, pulled out from the leading edge of the roll paper Pr set on the spool bearing bases 5a and 5b, is transported in the transport path 9 by the transport roller pairs 6a and 6b, the resist roller 10, and the resist pressure roller 17, as shown by the arrows in Figure 2. The control unit 110 controls the drive unit 7 to rotate the transport roller pair 6a, 6b, the resist roller 10, the resist pressure roller 17, etc. Below the roll of paper Pr(Pa,Pb), there are paper holders 8a and 8b to prevent the roll of paper Pr from falling.

[0029] The paper P is transported onto the platen 74 in the image forming unit 60 by passing through a transport path 9 supported by media transport guide members 18a, 18b, etc.

[0030] In the image forming unit 60, an image is formed when a liquid recording head ejects droplets of each color onto the paper P corresponding to the image data. The forward transport discharge unit for the paper P on which the image has been formed is provided with a cutter 76 that extends in the sub-scanning direction (paper width direction) and is used to cut the continuous paper P to a predetermined length.

[0031] To align the leading edge of the continuous paper P being transported, 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 moves in the main scanning direction Y by the drive motor to cut the paper P to a predetermined length. The cut paper P is discharged to the discharge section. Although Figures 1 and 2 show an example configuration of an image forming apparatus in which roll paper Pa and Pb can be set on two spool bearing bases 5a and 5b, an image forming apparatus with only one spool bearing base may also be used. Furthermore, 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 bases 5a and 5b), but from now on, identifiers a and b will not be used when they are not distinguished.

[0032] Furthermore, in this embodiment, for example, sensors may be provided on the spool bearing bases 5a and 5b to detect whether a spool has been set. Such sensors are also called spool detection sensors. By using spool detection sensors, it is possible to detect whether a roll of paper has been set. In addition, when a roll of paper is set, it becomes possible to perform processing such as displaying the paper feed screen on the display unit 170.

[0033] Here, we will explain the conventional method of setting up roll paper. Figure 3 illustrates a conventional method for setting roll paper. The roll paper Pr has flanges (flange members) at its widthwise ends, and a spool is set on them. The user sets the roll paper with the spool on the paper feed receiving section (spool bearing base) of the device (Figure 3(A)), finds the leading edge of the roll paper, and while holding the edge, rotates the roll paper with both hands as shown in Figure 3(B) so that the leading edge of the paper is facing the user. Next, the user inserts the roll paper while rotating it, positioning the leading edge of the paper between the guide plates at the back of the roll paper (Figure 3(C)). The guide plates are made of transparent material so that the paper can be seen, and consist of two plates, upper and lower. When the user rotates the roll paper inwards so that the leading edge of the paper is on top of the lower guide and inserts the paper into the back of the guide, the paper is fixed inside and pulled into the device.

[0034] As shown in Figure 3(C), the guide plate into which the leading edge of the paper is inserted is located behind the roll of paper, making it difficult to see as it is hidden by the roll. Furthermore, because the guide plate is transparent, it is possible that the paper is inserted above the upper guide plate when intended to be inserted between the two guide plates, requiring the user to start over. Additionally, if the guide plate were not transparent, it would be difficult to confirm whether the paper has been inserted between the two guide plates. In addition, it is necessary to insert the leading edge of the paper roll as evenly as possible, which is a delicate task. Furthermore, if the leading edge of the paper is not inserted evenly, it will be fed at an angle, causing skew, which can lead to having to restart the operation or causing a jam.

[0035] Furthermore, as shown in Figures 3(D) and (E), in a device with a two-tiered roll paper setting section, when a roll of paper is already set in the upper tier, if a roll of paper is to be set in the lower tier and the leading edge is to be inserted between the guide plates, the guide plates become even more difficult to see because the roll of paper in the upper tier is already there, increasing the difficulty of setting the paper and the risk of inserting it at an angle.

[0036] Therefore, in one embodiment of the paper feeding device, in a configuration for detecting the leading edge of the roll paper, the leading edge is detected by a sensor, and the paper is transported to the paper feeding section. The supply section is a means for supplying the roll paper to the supply destination, and is, for example, the transport roller pair 6 or the transport path 9 shown in Figure 2.

[0037] Figure 4 illustrates an example of setting a roll of paper onto a spool. Figures 4-41-43 show examples of removing an old roll of paper, and Figures 4-46 show examples of setting a new roll of paper. As shown in Figures 4-41-43, flanges are provided on both ends of the spool. After removing the flanges, the old roll of paper is removed from the spool. Then, as shown in Figures 4-4-46, the spool is inserted onto the new roll of paper, and the flanges are set.

[0038] In the examples shown in Figures 41-43, old roll paper is used, but if no paper is available, the paper core located inside the roll paper will be removed from the spool. The roll paper has a paper core inside, and the spool is inserted through the inside of the paper core and installed (set) in the paper feeding device. In addition, by using a flange, for example, the roll paper can rotate in conjunction with the rotation of the spool, but it is not limited to a flange.

[0039] The spool may be called a spool shaft or simply a shaft. The spool is, for example, cylindrical, and the inside of the cylinder may or may not be hollow. The spool's configuration is not particularly limited and can be selected as appropriate. The spool is basically not in contact with the paper tube, but this does not preclude configurations in which the spool and paper tube are in contact.

[0040] Figure 5 is a side view illustrating the main components of an example configuration of a paper feed device according to one embodiment. The paper feed device 90 comprises at least an arm 91, a roller 92, a sensor 93, and a pair of transport rollers 6 as a transport section. The paper feed device 90 may further include an entrance guide plate 95. In Figure 5, the position of the roll paper Pr when the user has set it in the paper feeder 90 is shown by a dashed line. The roll paper Pr is held in a modular component (not shown) so as to be rotatable with respect to the center (axis) of the roll paper.

[0041] The arm (guide plate) 91, which serves as a support member for the roll paper Pr, is configured to rotate around a pivot center 911. The arm 91 is pressed in the direction of the roll paper by a spring or the like on one side of the pivot center 911. As a result, the arm 91 will remain in contact with the outer diameter of the roll paper even if the roll paper diameter changes. The white arrow indicates the direction of rotation of the arm 91. Furthermore, the arm 91 has a roller 92 and a sensor 93 on the other side of the pivot center 911. Since the arm 91 is pressed in the direction of the roll paper, the roller 92 and sensor 93 are supported so as to be in contact with the surface of the roll paper Pr.

[0042] The arm 91 acts as a guide plate that guides the direction of transport of the roll paper Pr. The part of the arm 91 where the roll paper Pr is set (end side) should be shaped to follow the outer diameter of the roll paper (for example, an arc shape) 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 support member, arm 91, also serves as a guide plate for guiding the roll of paper, thereby reducing the number of parts and lowering costs.

[0043] The roller 92 and sensor 93 are positioned so as to face approximately the center of the roll paper (opposite the axis center of the roll paper) regardless of the roll paper diameter. The roller 92 is positioned at a different location from the sensor 93 in the circumferential direction of the roll paper Pr, and the roller 92 and sensor 93 are offset from each other in the circumferential direction. The sensor 93 can detect the step (paper thickness) at the leading edge of the roll paper Pr. Specifically, for example, the sensor 93 has a detection accuracy that allows it to detect the step at the leading edge of the roll paper Pr.

[0044] The entrance guide plate 95 guides the direction of transport of the paper peeled from the roll paper Pr. In the configuration example shown in Figure 5, during paper feeding (when the roll paper Pr is rotating forward), the arm 91, which acts as a guide plate, guides the paper on the upstream side in the paper transport direction, while the entrance guide plate 95 guides it on the downstream side.

[0045] Next, we will explain the control of the paper feeder's functions. Figure 6 is a functional block diagram illustrating an example of the functions of a paper feeder according to one embodiment. The control unit 110 controls the entire paper feeding device. Figure 6 shows an example of a functional block in which the control unit 110 controls the sensor 93, the motor drive circuits 120 and 140, and the display unit 170, with other functional blocks omitted. The functions of the control unit 110 may also be configured to be executed by a control unit 110 (see Figure 2) that controls the entire image forming apparatus.

[0046] The control unit 110 includes, for example, a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), and the like. The CPU executes various programs and controls the entire image processing system based on arithmetic processing and control programs. RAM is a volatile storage medium for high-speed reading and writing of information, and it functions as a work area when the CPU executes programs. ROM is a read-only, non-volatile storage medium in which various programs and control programs are stored.

[0047] The motor drive circuit 120 drives the motor under the control of the control unit 110, and drives the roll paper drive unit 130. The roll paper drive unit 130 rotates the roll paper in either the forward or reverse direction. The roll paper drive unit 130 uses, for example, a roll paper rotation motor. The motor drive circuit 140 drives the motor under the control of the control unit 110, thereby driving the transport drive unit 150. The transport drive unit 150 drives the transport unit 160. The transport unit 160 is a transport means for transporting paper, and is, for example, a pair of transport rollers 6. The display unit 170 displays information such as the operating status of the paper feed device.

[0048] Next, we will explain an example of the configuration of the arm as a support member and an example of the tip detection operation. Figure 7 illustrates an example of the configuration of an arm according to one embodiment, with (A) being a perspective view illustrating an example of an arm 91, (B) being a schematic diagram showing the external appearance of a sensor 93, and (C) being a side view illustrating an example of an actuator and side plate constituting the sensor 93.

[0049] The arm 91 is positioned such that, during the operation (reverse rotation) in which the sensor 93 detects the leading edge of the roll paper, the roller 92 is on the upstream side in the paper transport direction and the sensor 93 is on the downstream side.

[0050] The sensor 93 may be an encoder sensor in which a slit 932 is provided on the actuator 931. The sensor 93 may also be called a paper thickness sensor, an edge detection sensor, or the like. The actuator 931 is positioned between two side plates 933 that constitute the sensor housing, and its shaft 934 is fitted into bearings in the side plates 933, allowing it to rotate around the shaft 934. The actuator 931 has an asymmetrical shape with respect to the shaft 934, as shown in Figure 7(C), for example.

[0051] The sensor 93 has a light-emitting section and a light-receiving section (not shown), and detects the leading edge of the roll paper Pr by counting the number of times light passes through the slit 932 of the actuator 931 from the light-emitting section to the light-receiving section (by counting the number of signal waveforms). The sensor 93 has a resolution of, for example, about 5 μm / pulse, which makes it possible to detect a step difference equal to the thickness of the paper.

[0052] 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 lifting at the leading edge of the roll paper, and the output of the sensor 93 will not become unstable due to the thickness, stiffness, or curling of the paper, ensuring reliable detection of the leading edge. Furthermore, since the rollers 92 and the sensor 93 are offset in the circumferential direction, even if there are partial scratches or other imperfections, the proportion of the impact on both the rollers and the sensor is reduced, resulting in a configuration that is less prone to false detections. In the following explanation, two or more rollers 92 will also be referred to as the roller section.

[0053] Figure 8 illustrates an example of the operation for detecting the leading edge of a roll of paper. Figure 9 illustrates the difference depending on the positional relationship between the roller and the sensor. Figure 8 shows the process of the leading edge of the roll paper Pr passing through the roller 92 and the sensor 93, with (A) showing the state before the leading edge passes through the roller 92, (B) showing the state after the leading edge has passed through the roller 92 but before passing through the sensor 93, and (C) showing the state after the leading edge has passed through the sensor 93. Figure 9 shows the difference in slack generation during tip detection operation, with (A) the case where the roller 92 is downstream of the sensor 93 and (B) the case where the roller 92 is upstream of the sensor 93.

[0054] Sensor 93 and roller 92 are positioned in close proximity and offset (offset in the circumferential direction of the roll paper). Because roller 92 is 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 the step (paper thickness) on the surface of the roll paper as the leading edge while keeping its leading edge in close contact with the surface of the roll paper Pr. As a result, the output (detection result) of sensor 93 does not become unstable due to the thickness, stiffness, or curling of the paper, and sensor 93 can reliably detect the leading edge of the roll paper Pr.

[0055] In this embodiment, the roller 92 is positioned upstream of the sensor 93, but detection is also possible with the reverse arrangement (Figure 9(A)). However, positioning the roller 92 upstream of the sensor 93 is preferable because it allows for more reliable suppression of the paper roll's leading edge until just before detection. Furthermore, as shown in Figure 7, by providing two rollers 92 and placing a sensor between them, it becomes possible to more reliably hold down the leading edge of the roll paper compared to using only one roller 92.

[0056] Next, an example of a signal obtained by the sensor 93 will be described. Figure 10(A) is a diagram illustrating the positional relationship between the roller 92 and the sensor 93, the arm 91 on which the roller 92 and sensor 93 are positioned, and the roll paper tip Prs, etc. Figure 10(B) is an example of a signal waveform obtained by the sensor 93 in Figure 10(A).

[0057] In the example shown in Figure 10(A), similar to Figures 4 and 8, the roller 92 and sensor 93 are positioned at different locations in the circumferential direction of the roll paper Pr, and the roller 92 and sensor 93 are offset from each other in the circumferential direction. Also, O in the figure represents the axis center of the spool, and the sensor 93 and roller 92 are positioned toward the axis center of the spool. Furthermore, in the tip detection operation, the roller 92 is positioned upstream of the sensor 93.

[0058] In the diagram, (1) to (3) are regions divided according to the position of the roll paper leading edge Prs. (1) is the region when the roll paper leading edge Prs is upstream of the roller 92. (2) is the region when the roll paper leading edge Prs is downstream of the roller 92 and upstream of the sensor 93. (3) is the region when the roll paper leading edge Prs is downstream of the sensor 93. These are also referred to as region (1), region (2), and region (3).

[0059] As shown in Figure 10(B), the sensor signal value changes when the lead edge Prs of the roll paper moves from region (1) to region (2), and the sensor signal value changes when the lead edge Prs of the roll paper moves from region (2) to region (3). In this example, the sensor signal value in region (1) and the sensor signal value in region (3) are the same or close to each other.

[0060] Next, Figure 11 will be used to provide a supplementary explanation regarding the signal waveform shown in Figure 10(B). 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 where the roll paper leading edge Prs is moving through region (1), similar to Figure 10(A). In region (1), the sensor signal does not change and remains constant or approximately constant.

[0061] Figure 11(B) shows an example where the leading edge Prs of the roll paper is moving through region (2). When the leading edge Prs of the roll paper crosses region (1), in other words, when the leading edge Prs of the roll paper passes the roller 92, the arm 91 rotates toward the roll paper Pr by the thickness of the roll paper Pr. This is schematically shown by the white arrow in the figure. As the arm 91 rotates toward the roll paper Pr, the distance between the arm 91 and the roll paper Pr decreases, and the sensor 93 changes by the amount of this decrease in distance. This is schematically shown by the black arrow in the figure. This change in the sensor 93 can be described as a decrease in the distance between the base of the sensor 93 (the circular part in the figure) and the roll paper Pr, or as a change in the angle of the sensor's detection part (the L-shaped part in the figure) (the angle becoming smaller). Therefore, in region (2), the sensor signal becomes smaller, as shown in Figure 10(B). However, depending on the type of sensor, a signal waveform that makes the sensor signal larger is also acceptable. Furthermore, in region (2), when the rotation of arm 91 stops, the sensor signal remains constant or nearly constant until it reaches region (3).

[0062] Figure 11(C) shows an example where the leading edge Prs of the roll paper is moving through region (3). When the leading edge Prs of the roll paper crosses region (2), in other words, when the leading edge Prs of the roll paper passes the sensor 93, the angle of the sensor's detection part (the L-shaped part in the figure) increases by the thickness of the roll paper Pr. This is schematically shown 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 part in the figure) and the roll paper Pr remains unchanged. The sensor 93 in region (3) has the same shape as the sensor 93 in region (1). Alternatively, this can be expressed as the distance between the roll paper Pr and the sensor 93 being the same in region (1) and region (3). Therefore, in region (3), as shown in Figure 10(B), the sensor signal becomes the same value as in region (1), or close to it.

[0063] Next, we will explain in detail the waveform of the sensor signal in Figure 10(B). Figure 12 shows the waveform of the sensor signal in Figure 10(B), illustrating the boundaries between regions (1) and (3). As shown in Figure 12, the sensor signal has a slope at the boundary between region (1) and region (2), and at the boundary between region (2) and region (3). As illustrated, the sensor signal does not change discontinuously at the region boundaries, but rather changes continuously.

[0064] In this embodiment, the presence or absence of the roll paper's leading edge can be detected by detecting the slope K1 of a graph representing the change in the output intensity of the sensor signal as the leading edge of the roll paper passes through the roller 92 with respect to time, and the slope K2 of a graph representing the change in the output intensity of the sensor signal as the leading edge of the roll paper passes through the sensor 93 with respect to time. To put it in terms of Figure 12, the leading edge of the roll paper can be detected by detecting the slope K1 of the sensor signal as the leading edge of the roll paper Prs moves from region (1) to region (2), and the slope K2 of the sensor signal as the leading edge of the roll paper Prs moves from region (2) to region (3).

[0065] Note that while the graph showing the change in sensor signal output intensity is presented as a change over time, it may also be presented as a change over distance. For simplification, the slope of the graph showing the change in sensor signal output intensity over time may simply be referred to as the slope of the sensor signal.

[0066] Here, the slope of the sensor signal when the leading edge of the roll paper passes through roller 92 is referred to as slope K1, and the slope of the sensor signal when the leading edge of the roll paper passes through 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 may also be true. Depending on the type of sensor, slope K1 may be a positive value and slope K2 may be a negative value.

[0067] Next, regarding the fact that the sensor signal has a slope in the waveform of the sensor signal shown in Figure 12, Figures 13 to 15 will be used to provide a supplementary explanation. Figures 13(a) to 13(d) are time-series diagrams showing the movement of the lead edge of the roll paper Prs from the point indicated by the 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 are diagrams showing the movement of the lead edge of the roll paper Prs from the end of region (1) to region (2).

[0068] As shown in Figures 13(a) to (d), as the leading edge Prs of the roll paper passes through the roller 92, the distance between the roll paper Pr and the roller 92 gradually changes as the roller 92 rotates. As the leading edge Prs of the roll paper passes through the roller 92, it goes from Figure 13(a) to, for example, Figure 13(b) and Figure 13(c) and then to Figure 13(d). Therefore, the arm 91 rotates from Figure 13(a) to, for example, Figure 13(b) and Figure 13(c) and then to Figure 13(d). The movement of the roller 92 and the arm 91 is schematically shown by the white arrows.

[0069] The movement of the sensor 93 at this time is shown in Figures 14(a) to (d). Figures 14(a) to (d) correspond to Figures 13(a) to (d) and represent the same time series. As the arm 91 moves as shown in Figures 13(a) to (d), the sensor 93 gradually changes, for example, from Figure 14(a) through Figures 14(b) and 14(c) to Figure 14(d). For example, this can be described 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, as the leading edge of the roll paper Prs passes the roller 92, the sensor signal will have a tilt K1, as shown in Figure 12.

[0070] Figures 15(e) to 15(h) are time-series diagrams showing the movement of the lead paper roll, from the point indicated by the dashed line B in Figure 11(B), i.e., the position of sensor 93, to the position shown in Figure 11(C). In other words, they show the movement of the lead paper roll, from the point where it reaches the edge of region (2) to the position shown in region (3). Figure 15(e) shows the state at a later time than Figure 14(d).

[0071] Note that the position of dashed line B shown in Figure 11 and the position of dashed line B shown in Figure 15 are slightly different, but this does not affect the results in any way. The dashed line B shown in Figure 11 is a straight line passing through the contact point of sensor 93 when the leading edge Prs of the roll paper is located in region (1), and the dashed line B shown in Figure 15 is a straight line passing through the contact point of sensor 93 when the leading edge Prs of the roll paper is located in region (2).

[0072] As shown in Figures 15(e) to (h), when the leading edge Prs of the roll paper passes through the sensor 93, the sensor 93 gradually changes from Figure 15(e) to, for example, Figure 15(f) and Figure 15(g) and then to Figure 15(h). Therefore, as the leading edge Prs of the roll paper passes through the sensor 93, the sensor signal will have a tilt K2, as shown in Figure 12. Since the sensor 93 in this embodiment has a detection accuracy that can detect the step at the leading edge of the roll paper, it becomes possible to detect tilts K1 and K2.

[0073] Next, the details of the sensor signals shown in Figure 12 will be explained using Figure 16. Figure 16 is a diagram illustrating Figure 12. In the example shown in Figure 16, the sensor signal changes from point a1 to point a4 as the leading edge Prs of the roll paper passes through the roller 92. At this time, the slope K1 can be determined by selecting any points a2 and a3 between points a1 and a4. For example, if the horizontal axis of Figure 16 is x and the vertical axis is y, and the change from point a2 to point a3 is x1 and y1, then the slope K1 = y1 / x1, and the slope K1 can be determined. There are no particular restrictions, but the slope may be considered detected if the value of the slope K1 is within a predetermined range. Alternatively, multiple points may be selected, and the slopes of multiple points may be determined and the average calculated.

[0074] In the example shown in Figure 16, when the leading edge Prs of the roll paper passes the sensor 93, the sensor signal changes from point b1 to point b4. At this time, the slope K2 can be determined by selecting any points b2 and b3 along the path from point b1 to point b4. For example, if the horizontal axis in Figure 16 is x and the vertical axis is y, and the change from point b2 to point b3 is x² and y², then the slope K2 = y² / x², and the slope K2 can be determined. Similarly, although not particularly limited, a slope may be considered detected if the value of the slope K2 is within a predetermined range. Alternatively, multiple points may be selected, and the slopes of multiple points may be determined and the average calculated. In the example shown in Figure 16, the signs of slopes K1 and K2 are opposite.

[0075] In this way, by detecting the tilt K1 of the sensor signal when the leading edge of the roll paper passes through roller 92 and the tilt K2 of the sensor signal when the leading edge of the roll paper passes through sensor 93, the presence or absence of the leading edge of the roll paper can be detected. Furthermore, in this embodiment, by detecting both tilt K1 and tilt K2, the detection accuracy of the presence or absence of the leading edge of the roll paper can be improved.

[0076] Furthermore, as shown in Figure 16, it is preferable that the slope K1 of the sensor signal when the leading edge of the roll paper passes through roller 92 and the slope K2 of the sensor signal when the leading edge of the roll paper passes through sensor 93 are detected within a predetermined time T1. In this case, false detections due to irregularities on the surface of the roll paper can be suppressed.

[0077] T1 can be selected as appropriate, but it is preferable to do so as follows. When the circumferential distance from roller 92 to sensor 93 is L (mm), the linear velocity at the leading edge of the roll paper is V (mm / s), and the set margin time is m1 (s), then T1 is: T1 = L / V + m1 [s] This is preferable. By doing so, false detections due to irregularities on the surface of the roll paper can be suppressed, and detection failures at the leading edge of the roll paper can be suppressed.

[0078] Furthermore, if the leading edge of the roll paper is not detected even after one rotation of the roll paper or spool following the start of the roll paper leading edge detection operation, it is preferable to rotate the roll paper or spool further and repeat the detection operation. This can further improve detection accuracy. In this case, it is preferable to set the number of times the operation should be performed. By setting the number of times the operation should be performed, it is possible to avoid a situation where the detection operation is repeated without completion.

[0079] As shown in the above formula, T1 can be set arbitrarily. Furthermore, the set margin time m1(s) is not particularly limited and can be set as appropriate. For example, it may be set considering the type of sensor, the thickness of the roll paper, etc. However, m1 <T1である。

[0080] In this embodiment, the presence or absence of the leading edge of the roll paper is determined, for example, by the control unit 110. Furthermore, 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 its position in the circumferential direction of the roll paper.

[0081] In the above detection example, the presence of the lead end of the paper roll was determined when tilts K1 and K2 were detected within a predetermined time T1, but the present invention is not limited to this. As described below, by rotating the paper roll or spool multiple times and repeating the detection operation, it is also possible to determine that the lead end of the paper roll is present when tilt K1 or K2 is detected on the n+1th rotation, even if tilt K1 or K2 could not be detected on the nth rotation.

[0082] The details of the sensor signal shown in Figure 12 will be further explained using Figure 17. Figure 17 shows an example where the detection operation is repeated by rotating the roll paper or spool multiple times. Here, the signal waveform at the nth rotation and the signal waveform at the (n+1)th rotation are shown. n is an integer greater than or equal to 1, for example, 1.

[0083] In the detection example above, if tilt K1 and tilt K2 were detected within time T1 on the nth rotation, it was determined that the paper roll had a leading edge. For example, if two or more rollers 92 are arranged in the direction of the roll axis as shown in Figure 7, tilt K1 and tilt K2 may be difficult to detect if the leading edge of the paper is cut at an angle.

[0084] Therefore, in this example, after detecting inclination K1 and inclination K2, it may be possible to determine whether inclination K1 has been detected again within a predetermined time T2, and if inclination K1 is detected again, it may be determined that the leading edge of the roll paper is present. By doing so, the detection accuracy can be further improved. The predetermined time T2(s) is the time it takes for the roll paper or spool to complete one rotation plus a set margin time m2(s). The idea is that if inclination K1 is detected on the nth rotation, it is determined whether inclination K1 will be detected on the next n+1th rotation.

[0085] Similarly, after detecting inclination K1 and inclination K2, it may be determined whether inclination K2 was detected again within a predetermined time T2, and if inclination 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 inclination K1 is difficult to detect, it is preferable to detect inclination K2 and then determine whether inclination K2 was detected again within a predetermined time T2.

[0086] In particular, it is more preferable to repeatedly detect tilt K1 and tilt K2, and then determine whether tilt K1 or tilt K2 was detected again within a predetermined time T2. In this case, the detection accuracy can be further improved.

[0087] These examples demonstrate the processing of steps S21-S25, S28, and S29 in the flow chart shown in Figure 19, which will be described later.

[0088] The set margin time m2(s) is not particularly limited and can be selected as appropriate. Similar to m1 above, it may be set considering factors such as the thickness of the roll paper and the type of sensor. However, m2 <T2である。

[0089] This section provides supplementary information on how to determine whether tilt K1 will be detected again in the next (n+1)th rotation, given that tilt K1 was detected in the nth rotation. For example, if tilt is detected in the nth rotation, and that tilt is greater than or equal to a predetermined value, it may be determined that tilt K1 has been detected. Similarly, in the (n+1)th rotation, if tilt is detected, and that tilt is greater than or equal to a predetermined value, it may be determined that tilt K1 has been detected. The predetermined value can be selected as appropriate, but for example, if the absolute value of the detected tilt is 4 or greater, it can be determined that tilt K1 has been detected. After detecting tilt K1, it can be said that tilt K1 has been detected again within a predetermined time T2. The same applies to tilt K2; if the absolute value of the detected tilt is greater than or equal to a predetermined value, it may be determined that tilt K2 has been detected. Note that for tilt K2, before determining the absolute value, the sign of the tilt should be checked and determined to be different from tilt K1.

[0090] 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 the inclinations. When the inclination K1 at the n-th 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 have to exactly match. If the ratio of 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.

[0091] 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 n-th 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.

[0092] 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.

[0093] Next, we will explain an example of the process from setting the roll paper to performing the paper transport operation using an example flowchart. Figure 18 is a flowchart illustrating an example of the operation of setting the roll paper in a paper feeder according to one embodiment.

[0094] When the control unit 110 detects that the roll paper Pr has been set in the paper feed device (for example, detected by the detection result of the spool detection sensor) (S11), it controls the motor drive circuit unit 120 to control the roll paper drive unit 130 to reverse the direction of the roll paper Pr. The roll paper rotation motor (roll paper drive unit 130) rotates the roll paper Pr in the winding direction in reverse (S12), and the sensor 93 performs a leading edge detection operation (S13).

[0095] In the diagram, A refers to the process performed in the lead-edge detection operation in S13. The lead-edge detection operation in S13 follows the flow shown in Figure 19, A. Flow A is divided into two cases: when the lead edge of the roll paper is detected (S14) and when the process proceeds to flow E. Flow E is shown in Figure 20. Flow E is divided into two cases: when the lead edge of the roll paper is detected (S14) and when the lead edge of the roll paper is not detected (S18).

[0096] When the leading edge is detected by the sensor 93 (S14), the control unit 110 controls the motor drive circuit 120 to stop the roll paper rotation motor at the leading edge stopping position (S15), and then moves the leading edge of the roll paper in the transport direction by forward rotation (S16). The motor drive circuit 140 rotates the transport unit 160 to transport the leading edge of the paper into the device (S17).

[0097] In flow E, if the leading edge of the paper roll is not detected (S18), the paper roll rotation motor is stopped (S19). Subsequently, if necessary, processing such as displaying a warning on the display unit 170 is performed.

[0098] Next, the flowchart for part A in Figure 18 will be explained using Figure 19. The example flowchart for part A shown in Figure 19 is for performing the tip detection operation (S13). First, the number of tip detections N is set to 0 (S21). Next, it is determined whether tilt K1 has been detected (S22). If tilt K1 has been detected (if S22 is YES), it is determined whether tilt K2 has been detected within T1 (S23). If tilt K2 has been detected within T1 from tilt K1 (if S23 is YES), the tip detection count (N) is increased by 1 (S24).

[0099] Regarding the determination of whether a tilt K2 is detected within T1, for example, the method described in Figure 16 can be used. In addition, in S22, it may be referred to as determining whether a sensor displacement output (K1) is detected.

[0100] Next, it is determined whether the number of tip detections is equal to or greater than the set value a (S25). The set value a is the value that sets how many times it takes to determine that the tip has been detected. The set value a is an integer greater than or equal to 1, and the value can be increased if the reliability of the detection operation is to be improved. Figure 21 shows an explanation of the terms used in the flowchart.

[0101] If the number of tip detections is equal to or greater than the set value a (if S25 is YES), it is determined that the tip of the roll paper has been detected, or in other words, that there is a tip of the roll paper (S14). Next, the process proceeds to the main flow shown in Figure 18. Note that S14 is shown in both Figure 19 and Figure 18, so there is some overlap between the two, but it is shown this way simply for the sake of ease of understanding.

[0102] To reiterate the above explanation, for example, if the set value a is 1, then after detecting tilt K1, tilt K2 was detected within T1, so it was determined that the leading edge of the roll paper was present (S21~S25, S14).

[0103] 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, as shown in FIG. 19, S28 and S29 are performed. In S28, after detecting the slope K1, it is determined whether the slope K1 is detected again within T2. This is to determine whether the slope K1 is detected again within T2 as described in FIG. 17 above, and the detection accuracy can be improved.

[0104] In S28, when the slope K1 is detected again within T2 (when S28 is YES), after detecting the slope K1, it is determined whether the slope K2 is detected within T1 (S29). When S29 is YES, it returns to S24 and the number of leading edge detections (N) is incremented by 1. Again, the determination of S25 is performed. If YES, it is determined that there is a leading edge and returns to this flow. Thus, by performing S25, S28, and S29, the detection accuracy can be further improved.

[0105] In S22 of FIG. 19, when the slope K1 is not detected (when S22 is NO), it is determined whether there is an output from the leading edge detection sensor (sensor 93) (S26). When there is no output from the sensor (when S26 is NO), it is determined that the leading edge detection sensor is malfunctioning (sensor abnormality) (S27).

[0106] In the determination of S26, for example, it is determined whether there is an output from the leading edge detection sensor for a predetermined time. As the predetermined time, for example, it is preferably not less than the time for one rotation of the roll paper or spool. By doing so, false detection can be reduced.

[0107] If the judgment in S26 is YES, that is, if tilt K1 is not detected and there is an output from the tip detection sensor, the number of rotations of the roll paper is determined (S30). Here, it is determined whether it has rotated R times. As shown in Figure 21, R is the value set to determine how many times the roll paper will rotate until the tip is detected. Note that although the number of rotations of the roll paper is determined, the number of rotations of the spool may be determined instead. If the number of rotations of the roll paper is less than R (if the judgment in S30 is NO), the number of rotations is counted up (S31), and it is determined again whether tilt K1 was detected (S22).

[0108] In the processing flow of S22, S26, and S30, the tilt K1 is not detected, but since there is output from the tip detection sensor, it is assumed that the tip detection sensor is not malfunctioning. Because the tilt K1 is not detected for some reason, the roll paper is rotated repeatedly in an attempt to detect the tilt K1. By performing this process multiple times, it is possible to reduce the chances of the tip of the roll paper being missed from detection even though the tip is present.

[0109] If the number of roll rotations is R (if the judgment in S30 is YES), the process proceeds to flow E shown in Figure 20. Also, if the judgments in S28 and S29 are NO, in other words, if tilt K1 and tilt K2 are not detected, the process proceeds to flow E shown in Figure 20 after the judgment in S30. Flow E is the process that is followed when the leading edge of the roll paper is not detected in flow A.

[0110] Figure 20 is a flowchart showing an example of Flow E. First, the number of tip detections N is set to 0 (S41). Next, it is determined whether the tilt K2 has been detected (S42). In S42, this may also be referred to as determining whether the sensor displacement output (K2) has been detected.

[0111] If a tilt K2 is detected (if S42 is YES), the number of tip detections (N) is increased by 1 (S43). Next, it is determined whether the number of tip detections is equal to or greater than the set value a (S44). The set value a is the same as above and is the value that sets how many detections are required to determine that the tip has been detected. If the number of tip detections is equal to or greater than the set value a (if S44 is YES), it is determined that the tip of the roll paper has been detected, in other words, that there is a tip of the roll paper (S14). Next, the process proceeds to the main flow shown in Figure 18. Note that S14 is shown in both Figure 20 and Figure 18, so there is some overlap between the two, but it is shown this way simply for the sake of ease of understanding.

[0112] In S44, it is preferable that the set value a is 2 or greater, and that the process in S46 is performed at least once. That is, it is preferable to determine whether the inclination K2 was detected in multiple rotations. In the determination in S44, when inclination K2 is detected in the nth rotation of the roll paper or spool, it is preferable to determine whether inclination K2 was detected again in the n+1th rotation, and if inclination K2 is detected continuously for a predetermined number of rotations, it is preferable to determine that there is a leading edge of the roll paper. In this case, the leading edge of the roll paper can be detected with greater accuracy. For example, it is possible to suppress the misidentification of irregularities that are not the leading edge of the roll paper as inclination K2.

[0113] In S46, after detecting the tilt K2, it is determined whether the tilt K2 was detected again within T2. ​​This means that when the tilt K2 was detected at the nth rotation, it is determined whether the tilt K2 was detected again at the (n+1)th rotation (see Figure 17).

[0114] If the result in S42 is NO, that is, if tilt K2 is not detected, the number of rotations of the roll paper is determined (S45). Here, it is determined whether it has rotated R times. R is the same as above. If the number of rotations of the roll paper is less than R times (if the result in S45 is NO), the number of rotations is counted up (S31), and it is determined again whether tilt K2 is detected (S42).

[0115] If the number of roll rotations is R or greater (resulting in a YES judgment in S45), it is determined that there is no leading edge of the roll paper, and the roll paper rotation motor is turned OFF (S18, S19). Note that S18 and S19 are shown in both Figure 20 and Figure 18, so there is some overlap between the two, but this is done simply for the sake of clarity.

[0116] Furthermore, if the judgment in S46 is NO, in other words, if tilt K2 is not detected, after making the judgment in S45, it is determined that there is no leading edge of the roll paper and the roll paper rotation motor is turned OFF (S18, S19).

[0117] By performing the processes in S22, S26, and S30, and further performing the processes in S42, S44, and preferably S46, it is possible to detect the presence or absence of the leading edge of the roll paper based solely on the tilt K2, even if the tilt K1 is not detected. Furthermore, performing the process in S46 can improve the detection accuracy.

[0118] In this embodiment, the leading edge of the paper roll can be automatically and accurately detected simply by setting the spool in the holding section of the paper feed device. Furthermore, as described above, in this embodiment, the presence or absence of the leading edge of the paper roll can be determined by detecting the inclination K1 of the sensor signal when the leading edge of the paper roll passes the roller section and the inclination K2 of the sensor signal when the leading edge of the paper roll passes the leading edge detection sensor. Since it can be determined that the paper roll is set when the leading edge of the paper roll is detected, there is no need to provide components such as a reflective sensor. Therefore, it is possible to detect whether or not the paper roll is set without increasing the number of parts.

[0119] As will be discussed later, this embodiment prevents the system from performing the operation when a roll of paper is set, even if no roll of paper is actually set. Conventionally, the system detected that the spool was set in the holding unit and displayed the paper feed screen on the display unit 170 (operation unit). If no roll of paper is set and only the spool is set, paper cannot be fed, resulting in the operator having to close the paper feed screen. In this case, if the paper feed start button is accidentally pressed on the paper feed screen, the device will continue to operate until it determines that paper feeding has failed, and it will also be necessary to open the cover and stop the device, and to take action to restart the device, thus increasing the workload for the operator (which may also be called the user).

[0120] According to the present invention, it is possible to automatically and accurately detect whether a roll of paper is not set without increasing the number of parts, and to prevent the system from performing processing when a roll of paper is set, even though it is not.

[0121] Next, the operation for detecting an empty spool in the present invention will be described. In a paper feeder that feeds paper from a roll, for example, when a spool is set, it is detected by a sensor and the paper feed screen is displayed on the display unit 170 (also referred to as the operation unit, display panel, etc.). The paper feed screen displays a confirmation screen for the paper type (settings can be changed as needed), and buttons for starting and canceling paper feeding. When the paper feed start button is pressed, the automatic paper feeding operation is performed. The automatic paper feeding operation, for example, detects the leading edge of the roll of paper and transports the leading edge of the roll to the paper feed unit.

[0122] In such paper feeding devices, a spool that does not contain a roll of paper is also called an empty spool. The empty spool detection operation is the operation (which may also be called the determination operation) of detecting whether the set spool is an empty spool. In other words, for example, the empty spool detection operation is the operation of determining whether the set spool contains a roll of paper, and if the spool does not contain a roll of paper, the device determines that it is an empty spool.

[0123] Generally, there are cases where it is desirable to keep an empty spool in the roll paper holder even though paper feeding is not being performed. For example, this might occur when there is no place to put the spool, and it is desired to keep it in the paper feeding device. In conventional technology, if a spool without a roll of paper is placed in the paper feeding device, the system may perform the same processing as if a roll of paper were set, even though there is no roll of paper. This necessitates the operator to first stop the process, resulting in unnecessary work and time for the operator. In addition, there are other problems such as the need to stop and restart the device.

[0124] In conventional technology, even when an empty spool was placed in the roll paper holder, the paper feed screen and the paper feed start button would appear, requiring the user to cancel the operation by pressing the paper feed cancel button. If the paper feed start button was accidentally pressed while an empty spool was set, malfunctions such as the device continuing to operate until it recognized a paper feed failure would occur. Furthermore, if the paper feed start button was pressed, the user (including the operator) would have to open the cover and stop the device's operation, which would be an unnecessary hassle and take time. Moreover, if the device's operation was stopped by opening the cover, it would also be necessary to restart the device, which would be an even more troublesome and time-consuming process.

[0125] Furthermore, conventional technology had problems such as requiring a large number of parts to detect when the roll paper was not set, and being unable to improve detection accuracy. For example, one could consider a method that uses a reflective sensor to detect whether it is the roll paper or the spool shaft by detecting 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 an increase in the number of parts due to the addition of sensors, leading to increased costs, and the occurrence of false detections due to the influence of ambient light.

[0126] Furthermore, it is considered effective to determine that no roll paper is set on the spool if the sensor is positioned so that it does not contact the spool surface and no output is received from the sensor. However, this can sometimes cause vibrations in the guide plate supporting the sensor to be detected, so there is a need to improve the detection accuracy. Therefore, there is a need to improve the accuracy of detecting when no roll paper is set on the spool.

[0127] To solve these problems, the present invention detects whether an empty spool is present in the spool set in the paper feed device. The control unit in the present invention determines the presence or absence of a leading edge of the roll paper based on the sensor signal from the leading edge detection sensor, and also determines whether roll paper is loaded on the spool. This prevents the paper feeding operation from being performed incorrectly when there is no paper loaded on the spool, thus preventing the user from incurring unnecessary trouble and time.

[0128] Furthermore, as described later, the present invention provides recesses or protrusions on the spool, thereby improving the accuracy of detecting empty spools. The present invention can efficiently and automatically detect with high accuracy when a roll of paper is not set on the spool. In addition, the present invention can detect empty spools without increasing the number of parts.

[0129] The timing for detecting an empty spool in the paper feed device can be selected as appropriate, but one example is when the spool is placed on the roll paper holding section. It is preferable to perform empty spool detection when the spool detection sensor detects a spool.

[0130] Figure 22 shows the state in which the paper core 99 of the roll paper is in contact with the roller 92 and the sensor 93. For example, the spool 98 is fitted inside the paper core 99. When the paper wound on the paper core 99 is used up, the roller 92 provided on the arm 91 comes into contact with the paper core 99, and the sensor 93 also comes into contact with the paper core 99 and detects the paper core 99. In this case, the output of the sensor 93 is the detection and output of the unevenness of the surface of the paper core 99. The sensor signal when the surface of the paper core 99 and the sensor 93 come into contact will be an output like that shown in Figure 28, which will be described later.

[0131] The spool 98 in this invention has a recess 96a or a protrusion 96b on a part of its surface. Figure 22(A) shows an example with a recess 96a, and Figure 22(B) shows an example with a protrusion 96b. By having a recess 96a or a protrusion 96b in the spool 98, the detection accuracy of an empty spool can be improved. The protrusion 96b may or may not be in contact with the paper tube 99.

[0132] Figure 23 shows the state when the spool 98 is set without a roll of paper Pr. In other words, it is a diagram showing an example of a state where an empty spool is set. The spool 98 is placed, for example, on the roll paper holding section. As shown in the diagram, the sensor 93 is in 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 the surface of the spool 98 and outputting. Figure 23(A) is an example with one recess 96a, and Figure 23(B) is an example with two recesses 96a.

[0133] Figure 24, like Figure 23, shows the state when the spool 98 is set without the roll paper Pr set on the spool 98. In other words, it is a diagram showing an example of the state when an empty spool is set. Figure 24(A) is an example with one protrusion 96b, and Figure 24(B) is an example with two protrusions 96b.

[0134] The arrangement, number, and shape of the recesses 96a and protrusions 96b on the spool 98 can be changed as appropriate and are not limited to those shown in the figures. Also, although the pivot center 911 is omitted in Figures 22 to 24, as described above, the arm 91 is rotatable so that the roller 92 and sensor 93 face the axis center of the spool 98.

[0135] Figures 25 and 26 are schematic diagrams illustrating an example of the positional relationship between the recess 96a or protrusion 96b of the spool 98 and the roller 92 and sensor 93. In the figures, reference numeral 96 indicates the recess 96a or protrusion 96b, and when describing the recess 96a and protrusion 96b without distinction, they may be referred to as the recessed / protruding portion 96, etc. Furthermore, the surface of the spool 98 may have irregular shapes that were not intentionally created, but such irregular shapes may be distinguished from the above-mentioned recessed / protruding portion 96 and simply referred to as irregularities, etc. Reference numeral 4 in the figures indicates a flange, but is not limited to the examples shown.

[0136] Figure 25(A) shows an example where there are two protrusions 96, and the arm 91 has two rollers 92. The protrusions 96 are provided on the spool 98 such that when the spool 98 rotates in an empty spool state, the protrusions 96 are in a position to contact the rollers 92. When the spool 98 rotates, one protrusion 96 contacts one roller 92, and the other protrusion 96 contacts the other roller 92. The dashed lines in the vertical direction of the paper in the figure schematically show the direction of movement of the protrusions 96. The dashed line O in the figure schematically shows the axis of rotation of the spool 98.

[0137] When the spool 98 rotates in an empty spool state, the uneven portion 96 (for example, the recess 96a) comes into contact with the roller 92, causing events such as those shown in Figures 13(a) to (d). This results in the output of a sensor signal with a tilt, for example, from (1) to (2) in Figure 12. The recess 96a has a region towards the bottom of the recess and a region away from the bottom of the recess. In the region towards the bottom of the recess, events occur in the order shown in Figures 13(a) to (d), for example, while in the region away from the bottom of the recess, events occur in the reverse order of Figures 13(a) to (d). In the region away from the bottom of the recess, a sensor signal with a tilt, for example, from (2) to (3) in Figure 12, is detected. Therefore, when the roller 92 passes through the recess 96a, the output sensor signal is a sensor signal like that shown in Figure 12, for example, with the bottom portion at (2) absent or small.

[0138] The same considerations apply to the protruding portion 96b as to the recessed portion 96a, and a sensor signal with the opposite inclination to that of the recessed portion 96a is output. Note that when the protruding portion 96 contacts the roller 92, it may also be written as when the protruding portion 96 passes through the roller 92. An example of the sensor signal when the spool 98 has a protruding portion 96 is explained, for example, in Figures 29 to 32 described later.

[0139] In the example shown in Figure 25(A), when the roller 92 and the uneven surface 96 come into contact, the two uneven surfaces 96 and the two rollers 92 are positioned so that they come into contact on the same line. By providing two uneven surfaces 96 and arranging them in this position, false detections can be suppressed.

[0140] Figure 25(B) shows an example in which there is one protrusion 96, and the protrusion 96 is provided on the spool 98 such that when the spool 98 rotates in an empty spool state, the protrusion 96 is in a position to contact the sensor 93.

[0141] The same considerations apply to Figure 25(B) as to Figure 25(A). In Figure 25(B), the uneven portion 96 comes into contact with (or passes through) the sensor 93, resulting in events such as those shown in Figures 15(e) to (h). In the case of the recessed portion 96a, the events occur in the order shown in Figures 15(e) to (h) in the region toward the bottom of the recess, while the events occur in the region away from the bottom of the recess, following the reverse order of Figures 15(e) to (h). The same considerations apply to the convex portion 96b as to the recessed portion 96a, and a sensor signal with the opposite inclination to that of the recessed portion 96a is output.

[0142] Figure 25(C) shows an example with one protrusion 96, where the protrusion 96 is provided on the spool 98 so that it contacts the roller 92 and sensor 93 when the spool 98 rotates in an empty spool state. In addition, in the example shown in Figure 25(C), the width of the protrusion 96 is larger than in the example above. In other words, the length of the spool 98 in the rotation axis direction is larger.

[0143] In the example shown in Figure 25(C), for example, the uneven surface 96 contacts the sensor 93, and then the uneven surface 96 contacts the roller 92. In other words, the timing of the uneven surface 96 contacting the sensor 93 and the timing of the uneven surface 96 contacting the roller 92 are different. Therefore, the output of the uneven surface 96 is detected when the uneven surface 96 passes the sensor 93 and when the uneven surface 96 passes the roller 92. As a result, the output of two sensor signals is detected by a single uneven surface 96, thus suppressing false detections.

[0144] Figures 26(D) and (E) show further variations, illustrating examples where the arrangement and number of the protrusions 96 are changed. As shown in Figure 26(D), the protrusions 96 in Figure 26(C) may be separated. Alternatively, as shown in Figure 26(E), the number of protrusions 96 may be increased, but this will increase the manufacturing effort.

[0145] Figures 27(A) to (D) show examples of recesses 96a and protrusions 96b. While they can be selected as appropriate, for example, the height may change discontinuously, as in Figures 27(A) and (C), or the height may change continuously, as in Figures 27(B) and (D). Considering the grip on the roller 92 or sensor 93, (B) and (D) are preferred. Furthermore, the depth of the recess 96a and the height of the protrusion 96b are not particularly limited, but for example, it is preferable that the slope of the sensor signal when passing through the uneven surface 96 is greater than or equal to the slope of the sensor signal K1max and / or K2max when detecting the leading edge of the maximum usable paper thickness.

[0146] Next, we will explain examples of sensor signal outputs, particularly examples of tilt in sensor signals. Figure 28 shows an example of the output shown in Figure 22, and is an example of the output of the sensor signal on the surface of the paper tube 99. As shown in Figure 22, this is an example of the output when the spool 98 rotates with the paper tube 99 of the roll paper in contact with the roller 92 and the sensor 93.

[0147] As shown in Figure 28, the surface of the paper tube 99 has irregularities and undulations, so the signal is not constant but varies with a certain range. The range of variation is smaller than the output intensity of the paper's unevenness. The magnitude in the vertical axis direction of the sensor signal is also referred to as the output intensity. The range of variation may also be referred to as the variation in output intensity.

[0148] Figure 29 is a schematic diagram illustrating the movement of the roller 92 and arm 91 as the roller 92 passes through the recess 96a. The upper diagram in the figure is similar to Figure 23(A) and schematically shows the arrangement of the roller 92 and the recess 96a. The lower diagram in the figure schematically shows the movement of the roller 92 as it passes through the recess 96a in chronological order. The white arrows in the figure represent the chronological order.

[0149] In the lower section of the diagram, (a) to (c) are shown in chronological order. (a) shows the point in time before the roller 92 passes through the recess 96a. (b) shows the moment when the roller 92 is moving towards the bottom of the recess 96a. The black arrows in the diagram schematically show the movement of the roller 92 and the arm 91. As the roller 92 moves towards the bottom of the recess 96a, the arm 91 moves closer to the spool 98. (c) shows the moment when the roller 92 exits the bottom of the recess 96a. As the roller 92 exits the bottom of the recess 96a, the arm 91 moves away from the spool 98.

[0150] Figure 30 is a diagram illustrating an example of the sensor signal output and an example of the sensor signal slope in the example shown in Figure 29. First, Figure 30(A) shows an example of contact with the roller 92. Since the side surface or cross-section of the roller 92 is circular, the rate of change in the sensor signal value per unit time when passing through the recess 96a increases as it approaches the bottom of the recess 96a and decreases as it exits the bottom of the recess 96a.

[0151] Therefore, an example of the sensor signal output when the roller 92 passes through the recess 96a is a curved valley shape, as shown in Figure 30(B). Plotting the slope of the sensor signal at this time results in the change shown in Figure 30(C). Note that (a) to (c) in Figures 30(B) and (C) correspond to (a) to (c) in Figure 29. The vertical axis in Figure 30(B) is the sensor signal output, denoted as output intensity y, and the vertical axis in Figure 30(C) is the slope k of the sensor signal. In addition, although the time axis is plotted from left to right in Figures 30(B) and (C) for convenience, it is not limited to this, and the time axis may also be plotted from right to left.

[0152] Figure 30(C) shows KS, K1max, and K2max, which are set values. By comparing the detected inclination with the set values, the recess 96a can be detected. K1max is the inclination of the sensor signal when the roller 92 passes the leading edge of the maximum usable paper thickness, and K2max is the inclination of the sensor signal when the sensor 93 passes the leading edge of the maximum usable paper thickness. K1max and K2max are determined in advance. KS is a set value obtained by adding a margin m to K1max. The reason for adding a margin m is to account for sensor variations, etc.

[0153] Furthermore, in Figure 30(C), KS is shown as K2max plus a margin m. While it is assumed that KS is set to a single value, the values ​​may be separated for the K1max and K2max sides. However, since the absolute values ​​of K1max and K2max are expected to be close, it is acceptable to set a single value for KS by adding a certain margin m to either K1max or K2max. Alternatively, KS may be the larger of the value obtained by adding a predetermined margin m to the absolute value of K1max or the value obtained by adding a predetermined margin m to the absolute value of K2max.

[0154] In Figure 30(C), the slope k is denoted as "KS" even in the negative region. This is for convenience, and it may be written as "-KS" considering the sign. To determine whether the detected slope is greater than KS, one can compare the two using their absolute values, for example. In the following explanation, it may be assumed that the comparison is made using absolute values. For example, in the example of the slope of the sensor signal shown in Figure 30(C), KS is greater than K1max, and since this is a comparison using absolute values, it can be said that KS is greater than K1max.

[0155] The above example described the case of the recess 96a, but it can also be applied to the convex portion 96b. In the case of the convex portion 96b, when the convex portion 96b passes through the roller 92, the sensor output is reversed in polarity compared to the recess 96a.

[0156] Furthermore, the sensor output when the recess 96a passes through the sensor 93 has the opposite sign to the sensor output when it passes through the roller 92. That is, in the output example in Figure 30(B), the waveform is convex upwards (positive side).

[0157] Figure 31 shows another example of the sensor signal output when detecting the recess 96a, and is an example of the output shown in Figures 23(A) and 25(A). In the example shown in Figure 25(A), the spool 98 rotates with the sensor 93 in contact with the surface of the spool 98, so the variation range shown in Figure 31 is output due to the irregularities and undulations on the spool 98.

[0158] As shown in Figure 31, when the spool 98 is rotated in an empty spool state, a peak p1 is output when the recess 96a provided in the spool 98 passes over the roller 92. This peak p1 corresponds to the recess 96a. The control unit 110 can detect the recess 96a based on the sensor signal from the sensor 93, and when it detects the recess 96a, it determines that the spool is empty.

[0159] For example, in the example shown in Figure 31, if the slope of the K1K region is greater than that of KS (for example, (b) in Figure 30(C)), it can be determined that there is a recess 96a and that the spool is empty. As mentioned above, it is preferable to compare the two using absolute values. Also, for example, in the example shown in Figure 31, if the slope of the K2K region is greater than that of KS (for example, (c) in Figure 30(C)), it can be determined that there is a recess 96a and that the spool is empty.

[0160] When determining the presence of a recess 96a, the following conditions can be appropriately selected: that the slope of the K1K region is greater than that of KS, that the slope of the K2K region is greater than that of KS, or that both conditions are met. By satisfying either the K1K or K2K region, detection failures can be reduced, and by satisfying both the K1K and K2K regions, false detections can be reduced.

[0161] The example shown in Figure 31 is an example where the recess 96a passes through the roller 92, but when the recess 96a passes through the sensor 93, the sensor output and sign will be reversed compared to when it passes through the roller 92.

[0162] Furthermore, in the example shown in Figure 31, the time for detecting an empty spool is set to be longer than the time it takes for one rotation of the paper roll (more than one full rotation). By setting the time for detecting an empty spool to be longer than the time it takes for one rotation of the paper roll, an empty spool can be reliably detected.

[0163] Furthermore, since the detection of an empty spool and the detection of the leading edge of the roll paper can be performed simultaneously, in this embodiment, it is preferable that the spool 98 to be judged is rotated for a time equal to or longer than one rotation of the roll paper, in order to determine whether or not the leading edge of the roll paper is present and whether or not the roll paper is loaded onto the spool 98.

[0164] Figure 32 shows an example of the output for the example shown in Figure 23(B). In this example, two recesses 96a are detected when one rotation of the roll paper is detected, and this is an example of the output when detection is performed on the example shown in Figure 25(C) and Figure 26(E).

[0165] In Figure 32, peaks p1 and p2 are output. Here, since the shapes of the two recesses 96a are identical (or nearly identical), peaks p1 and p2 have the same (or nearly identical) shape. If there are multiple recesses 96a, it may be determined that a recess 96a has been detected if the slope of any one of them is greater than KS, or if the slopes of multiple recesses are greater than KS.

[0166] In the example above, the case of the recess 96a was used as an example, but the matters described above also apply to the convex portion 96b. Since the convex portion 96b has a region that rises to the top of the convex portion and a region that descends from the top of the convex portion, the sensor output of the convex portion 96b is the opposite of that of the recess 96a.

[0167] When multiple recesses 96 are provided on the spool 98, it is preferable that they be provided at regular intervals (equal intervals) in the circumferential direction. The example shown in Figure 30 is an example where the recesses 96a are provided at regular intervals in the circumferential direction. By doing so, a more distinctive output can be obtained, and the detection accuracy of empty spools can be improved.

[0168] Figure 33(A) shows side-by-side examples of output detected for a spool 98 with one recess 96a (solid waveform S1) and output detected for a roll of paper with the maximum usable paper thickness (dashed waveform S2). Note that waveform S1 is the same as in Figure 31. Figure 33(B) is a diagram to explain which part of the slope K1max and K2max represent in Figure 33(A).

[0169] The shapes of the recess 96a and the protrusion 96b can be selected as appropriate, but it is preferable that the shapes are determined such that the slope of the sensor signal of the sensor 93 is greater than the slope of the sensor signal when detecting the leading edge of the maximum usable paper thickness. In this case, the recess 96a and the protrusion 96b become easier to detect in the sensor signal, making it easier to distinguish between the recess 96a and the protrusion 96b, and preventing false detections.

[0170] When the shapes of the recess 96a and the protrusion 96b are set in this manner, the control unit 110 determines that the spool is empty (no roll paper is loaded onto the spool 98) if it detects a slope greater than the slope of the sensor signal when detecting the leading edge of the maximum usable paper thickness. For example, the slope of the K1K region at peak p1 in Figure 33 is as shown in Figure 30(C), and since it is greater than K1max, it can be determined that the recess 96a has been detected.

[0171] Let's explain the above example again. In the sensor signal of sensor 93, let K1max be the slope of the sensor signal when the leading edge of the maximum usable paper thickness passes through roller 92, and let K2max be the slope of the sensor signal when the leading edge of the maximum usable paper thickness passes through sensor 93. K1max and K2max are determined in advance. Then, the control unit 110 preferably determines that there is no roll paper in the spool 98 (it is an empty spool) when it detects a slope in the sensor signal obtained by rotating the spool 98 that has the same sign as K1max and whose absolute value is greater than K1max, and / or a slope that has the same sign as K2max and whose absolute value is greater than K2max. By doing so, an empty spool can be detected with high accuracy.

[0172] Let's explain a preferred example again for the above example. When KS is the larger of the value obtained by adding a predetermined tolerance to the absolute value of K1max and the value obtained by adding a predetermined tolerance to the absolute value of K2max, it is preferable for the control unit 110 to determine that there is no roll paper in the spool 98 (it is an empty spool) when it detects a slope in the sensor signal obtained by rotating the spool 98 to be judged where the absolute value is larger than KS. In this way, sensor variations and the like can be taken into consideration, and an empty spool can be detected with even greater accuracy.

[0173] The predetermined tolerance value corresponds to the margin m mentioned above. The predetermined tolerance value may also be referred to as the predetermined value, tolerance amount, or set amount. The tolerance value (predetermined value) should be adjusted as appropriate depending on the specifications of the sensor used. For example, if a sensor that outputs 20 pulses for a paper thickness of 0.1 mm is used, assuming a variation equivalent to 0.05 mm, the tolerance value (predetermined value) can be set to 10 pulses, or 50% of the absolute value of K1max.

[0174] Furthermore, the example shown in Figure 33 is an example in which the shapes of the recess 96a and the protrusion 96b are determined so that the output intensity of the sensor signal of sensor 93 is greater than the output intensity of the sensor signal when detecting the leading edge of the maximum usable paper thickness. Here, we will explain the example where the recess 96a is the concave portion 96.

[0175] In this embodiment, the shape of the recess 96a or the protrusion 96b is preferably such that the output intensity of the sensor signal from the sensor 93 is greater than the output intensity of the sensor signal when detecting the leading edge of the maximum usable paper thickness. In this case, it is preferable that the control unit 110 determines that no roll paper is provided on the spool 98 when it detects an output intensity greater than the output intensity of the sensor signal when detecting the leading edge of the maximum usable paper thickness. This prevents false detections.

[0176] In the figure, the output strength of the sensor signal when detecting the leading edge of the maximum usable paper thickness is denoted as b, and the output strength of the sensor signal when the recess 96a passes through the roller 92 is denoted as c. As shown in the figure, the output strength c is greater than the output strength b. When such an output strength c is detected, that is, when an output strength greater than the output strength b is detected, the control unit 110 can determine that the recess 96a has been detected and that the spool is empty.

[0177] When the uneven portion 96 is a concave portion 96a, as shown in the figure, the output intensity b and output intensity c increase in the negative direction from the base (0 in the figure). Therefore, although not particularly limited, when comparing output intensity b and output intensity c, it is also possible to compare them using their absolute values. Alternatively, the sign of the sensor signal output intensity may be reversed so that they can be compared using positive values. Furthermore, when the uneven portion 96 is a convex portion 96b, the sign of output intensity b and output intensity c is reversed, so when comparing output intensity b and output intensity c, they should be compared using their absolute values.

[0178] In the figure, 'a' indicates the range of variation (variation in output intensity) when the surface of the paper tube 99 is detected. 'a' in the figure represents the same range of variation as in Figure 28. When setting the shapes of the recess 96a and the protrusion 96b, it is preferable to consider the range of variation, such as the variation in sensor sensitivity. Furthermore, when setting the shapes of the recess 96a and the protrusion 96b, it is preferable to consider the paper thickness. For example, it is preferable to set the shapes of the recess 96a and the protrusion 96b by considering how much difference there should be between output intensity b and output intensity c.

[0179] Furthermore, in the illustrated output example, the peak at the leading edge of the paper and the peak p1 of the recess 96a are positioned at the same location, but the present invention is not limited to this. In other words, in the horizontal axis direction, the peak at the leading edge of the paper and the peak p1 of the recess 96a are positioned at the same location, but the present invention is not limited to this. The positions of the peaks may be offset.

[0180] Figure 34 is a supplementary diagram showing an example of a signal waveform for detecting the leading edge of a paper roll. It illustrates the waveform changes when the leading edge of the paper roll passes the roller 92 and when the leading edge of the paper roll passes the sensor 93. The leading edge of the paper roll can be detected based on the slope of the sensor signal. In the illustrated example, the vertical axis represents the output intensity y of the sensor signal, and the horizontal axis represents time t.

[0181] If the system determines that the spool is empty, subsequent processing can be selected as appropriate. For example, it is preferable not to display the paper feed screen when the spool is empty. By not displaying the paper feed screen in this way, the user can avoid the hassle of canceling the paper feed by pressing the paper feed cancel button. It also prevents the user from accidentally pressing the paper feed start button, prevents malfunctions such as the system continuing to operate until it recognizes a paper feed failure, and saves the user the extra effort and time of having to open the cover and stop the system's operation.

[0182] To achieve the above, the paper feed device includes a spool detection sensor that detects when the spool is mounted on the spool bearing base, and a display unit capable of displaying a paper feed screen. When the control unit detects that the spool is mounted using the spool detection sensor, it rotates the spool to determine whether the roll paper is mounted on the spool before displaying the paper feed screen on the display unit. If it determines that the roll paper is not mounted on the spool, it prevents the paper feed screen from being displayed on the display unit.

[0183] Furthermore, the control unit may display a warning on the display unit 170 if it determines that no roll paper is loaded onto the spool. Displaying a warning in this way informs the user, thereby preventing accidental paper feeding operations.

[0184] As described above, the arrangement and number of the uneven parts 96 can be changed as appropriate. A preferred example is that the uneven parts 96 are provided at both the position where they contact the roller 92 and the position where they contact the sensor 93. This prevents the system from mistakenly detecting an empty spool even if there is a large scratch on the surface of the roll paper, despite the roll paper being set.

[0185] In other words, it is preferable to do the following: The recess or the protrusion is provided at both a position that contacts the tip detection sensor and a position that contacts the roller when the spool is installed in the paper feeding device and rotates without the paper and paper core on the spool. The control unit then preferably determines that the roll paper is not loaded onto the spool by detecting both the inclination of the sensor signal when the roller passes the recess or the protrusion and the inclination of the sensor signal when the tip detection sensor passes the recess or the protrusion when the spool rotates.

[0186] Next, I will explain an example of a workflow that takes the above into consideration. Figure 35 is an example of a flowchart for part A of Figure 18. In this embodiment, the leading edge of the paper roll and the empty spool can be detected simultaneously.

[0187] In this example, as shown in Figure 35, it is first determined whether tilt has been detected from the sensor signal (S61). If no tilt is detected in the sensor signal during the roll paper rotation operation in automatic paper feeding, and the sensor output remains constant for a certain period of time, it is determined that there is an abnormality in the tip detection sensor and the operation is stopped. This is the process for when the result is NO in S61 and NO in S71 of the flow chart. Furthermore, it is preferable to stop the operation by stopping the drive system and displaying a warning screen, as shown in S73. Note that S30 and S31 are the same as in Figure 19, so their explanation is omitted.

[0188] In the determination in S61, there are no particular restrictions on how to determine whether a tilt has been detected, but for example, it can be done by determining whether the detected tilt is greater than a predetermined value. The predetermined value here can be appropriately selected considering the variability of the sensor, etc.

[0189] When a tilt is detected in the sensor signal during the roll paper rotation operation in automatic paper feeding (YES in S61), the detected tilt is compared with KS (S62). The comparison between the detected tilt and KS can be performed as described above. Here are some examples. For example, it is determined whether a tilt has been detected in which the absolute value of the detected tilt is greater than KS. In addition, for example, it may be compared with K1max or K2max instead of KS (see also Figure 36 below). For the detected tilt, it may be determined whether the absolute value of the measured value with the same sign as K1max is greater than K1max, or whether the absolute value of the measured value with the same sign as K2max is greater than K2max.

[0190] If the detected tilt is greater than KS, it is determined that the spool is empty and the operation is stopped (S63, S64). It is preferable to stop the operation by stopping the drive system and displaying a warning screen, as in S64. Also, if the spool is empty (YES in S62), the process returns to the flow in Figure 18 and S18 and S19 are performed. However, S19 and S64 are the same process. In this case, the transition is shown with a dashed line in Figure 18. If it is determined that the spool is empty, it is not necessary to execute the flow in E.

[0191] In the determinations in S61 and S62, it is preferable to perform the determination of whether or not tilt has been detected, and the comparison of the detected tilt with KS, for a period of time equal to or longer than one rotation of the roll paper. In this case, it is possible to reliably determine whether or not the spool is empty.

[0192] If the detected tilt is less than or equal to KS (NO in S62), it is determined that the spool is not empty, and a determination is made (S22) as to whether tilt K1 was detected. If the result in S22 is YES, a determination is made (S23) as to whether tilt K2 was detected. These steps can be performed in the same way as shown in Figure 19, for example, so the explanation is omitted.

[0193] Figure 36 is another example of the flowchart for part A of Figure 18. In Figure 35, the detected slope was compared with KS, but in this example, the detected slope is compared with K1max and K2max. Note that here, only the differences from the above will be explained, and explanations of the same matters will be omitted.

[0194] First, as described above, it is determined whether tilt has been detected from the sensor signal (S61). If tilt is detected in the sensor signal during the roll paper rotation operation in automatic paper feeding (if YES in S61), the detected tilt is compared with K1max (S65). In S65, it is determined whether the detected tilt has the same sign as K1max, and whether the absolute value of the detected tilt is greater than K1max. If these conditions are met (if YES in S65), a flag is set (S66).

[0195] Whether the result of S65 is YES or NO, the next step is to compare the detected slope with K2max (S67). In S67, it is determined whether the detected slope has the same sign as K2max, and whether the absolute value of the detected slope is greater than K2max. If these conditions are met (YES in S67), a flag is determined (S68). If the result of S68 is YES, that is, if a slope greater than K1max is detected and a slope greater than K2max is detected, it is determined that the spool is empty and the operation is stopped (S63, S64).

[0196] Thus, in Figure 36, if a slope greater than K1max is detected and a slope greater than K2max is detected, it is determined to be an empty spool, thus enabling more reliable detection of empty spools.

[0197] As described above, the lead-edge detection operation of the paper roll and the empty spool detection operation can be performed. The above example flow uses inclination for judgment, but if judgment is to be made using output intensity, it can be modified as appropriate. For example, in Figure 35, the judgment in S61 can be changed to determine whether a predetermined output intensity has been detected, and the judgment in S62 can be changed to determine whether the detected output intensity is greater than output intensity b. Output intensity b is the output intensity of the lead-edge of the paper roll when the maximum usable paper thickness is reached.

[0198] Furthermore, in this invention, the roller 92 and the sensor 93 are positioned at offset locations. That is, the roller 92 and the sensor 93 are positioned at different locations relative to each other in the circumferential direction of the roll paper. Therefore, even if there are partial scratches or other defects on the surface of the roll paper, the leading edge of the roll paper can be detected. In addition, by being positioned at offset locations, false detections can be reduced even during the detection operation of an empty spool.

[0199] In the above description, the terms "detection" and "prediction" are used, but the present invention is not limited by the notation of these terms. For example, "detection" is used in the sense of detecting an empty spool, detecting the leading edge of a paper, or detecting uneven surfaces, while "prediction" is used in the sense of detecting tilt in a sensor signal, or detecting output intensity. In the present invention, these terms may be changed as appropriate; for example, "detection" and "prediction" may be swapped, or other terms such as "judgment," "discrimination," "identification," or "certification" may be used.

[0200] Examples of the present invention are as follows: <1> A paper feeder that supplies paper from a roll of paper in which a long sheet of paper is wound, A support member is provided which a tip detection sensor and a roller are arranged and which supports the tip detection sensor and the roller so that they contact the surface of the roll paper, The system includes a control unit that acquires the sensor signal from the aforementioned tip detection sensor, The aforementioned roll of paper has a paper core inside, and a spool is inserted inside the paper core and provided in the paper feeding device, and rotates in conjunction with the rotation of the spool, The tip detection sensor and the roller portion are arranged toward the axial center of the spool, The roller portion is positioned in a different location from the tip detection sensor in the circumferential direction of the roll paper. The aforementioned tip detection sensor is capable of detecting the step at the leading edge of the roll paper, The spool has a recess or protrusion on a part of its surface, The recess or protrusion is positioned to contact the tip detection sensor or the roller when the spool is installed in the paper feeding device and rotates without the paper and paper core on the spool. The control unit determines, based on the sensor signal from the tip detection sensor, whether or not there is a tip of the roll paper, and whether or not the roll paper is loaded onto the spool. A paper feeding device characterized by the following features. <2> The control unit determines the presence or absence of the tip of the roll paper by detecting the slope K1 of a graph representing the change in the output intensity of the sensor signal as the tip of the roll paper passes the roller part with respect to time, and the slope K2 of a graph representing the change in the output intensity of the sensor signal as the tip of the roll paper passes the tip detection sensor with respect to time. Characterized by <1> The paper feed device described above. <3> The shape of the recess or the protrusion is determined such that the output intensity of the sensor signal of the tip detection sensor is greater than the output intensity of the sensor signal when detecting the tip of the maximum usable paper thickness. The control unit determines that the roll of paper is not loaded onto the spool if it detects an output intensity greater than the output intensity of the sensor signal when detecting the leading edge of the maximum usable paper thickness. Characterized by <2> The paper feed device described above. <4> In the sensor signal of the aforementioned tip detection sensor, let K1max be the slope of the sensor signal when the tip of the paper with the maximum usable paper thickness passes the roller section, and let K2max be the slope of the sensor signal when the tip of the paper with the maximum usable paper thickness passes the tip detection sensor. Then, K1max and K2max are determined in advance. The control unit determines that the roll paper is not provided on the spool if, in the sensor signal obtained by rotating the spool to be judged, it detects a slope that has the same sign as K1max and whose absolute value is greater than K1max, and / or if it detects a slope that has the same sign as K2max and whose absolute value is greater than K2max. Characterized by <1> from <3> A paper feeder as described in any of the following. <5> When KS is the larger of the value obtained by adding a predetermined tolerance to the absolute value of K1max and the value obtained by adding a predetermined tolerance to the absolute value of K2max, The control unit determines that the roll paper is not present on the spool if it detects a slope in the sensor signal obtained by rotating the spool to be judged that is greater than the absolute value of KS. Characterized by <4> The paper feed device described above. <6> The recesses or protrusions are provided in two or more locations on the surface of the spool. Characterized by <1> from <5> A paper feeder as described in any of the following. <7> The control unit rotates the spool to be judged for a time equal to or longer than one rotation of the roll paper, determines whether or not there is a leading edge of the roll paper, and determines whether or not the roll paper is mounted on the spool. Characterized by <1> from <6> A paper feeder as described in any of the following. <8> A spool detection sensor that detects that the spool is mounted on the spool bearing base, It includes a display unit capable of displaying the paper feed screen, When the control unit detects that the spool is installed using the spool detection sensor, it rotates the spool to determine whether the roll paper is installed on the spool before displaying the paper feed screen on the display unit. If it determines that the roll paper is not installed on the spool, it does not display the paper feed screen on the display unit. Characterized by <1> from <7> A paper feeder as described in any of the following. <9> If the control unit determines that the roll paper is not loaded onto the spool, it will display a warning on the display unit. Characterized by <8> The paper feed device described above. <10> The recess or protrusion is provided at both a position that contacts the tip detection sensor and a position that contacts the roller when the spool is installed in the paper feeding device and rotates without the paper and paper core on the spool. The control unit determines that the roll paper is not loaded onto the spool by detecting both the inclination of the sensor signal when the roller passes the recess or the protrusion, and the inclination of the sensor signal when the tip detection sensor passes the recess or the protrusion, as the spool rotates. Characterized by <1> from <9> A paper feeder as described in any of the following. <11> <1> from <10> An image forming apparatus characterized by comprising a paper feeding device as described in any of the following. [Explanation of Symbols]

[0201] 6 Conveyor roller pairs 90, 90A paper feeder 91, 91A tonearm 92 Koro 93 Sensors 95 Entrance Guide Sign 96 Uneven part 96a Recess 96b protrusion 97 Support Member 98 Spool 99 Paper tube 100, 110 control unit 120, 140 Motor drive circuit section 130 Roll paper drive unit 150 Conveyor drive unit 160 Conveying section 170 Display section 911 Rotation center 931 Actuator 932 Slit 933 Side panel 934 axis [Prior art documents] [Patent Documents]

[0202] [Patent Document 1] Japanese Patent Publication No. 2018-150107 [Patent Document 2] Japanese Patent Publication No. 2021-113118

Claims

1. A paper feeder that supplies paper from a roll of paper in which a long sheet of paper is wound, A support member is provided which a tip detection sensor and a roller are arranged and which supports the tip detection sensor and the roller so that they contact the surface of the roll paper, The system includes a control unit that acquires the sensor signal from the aforementioned tip detection sensor, The aforementioned roll of paper has a paper core inside, and a spool is inserted inside the paper core and provided in the paper feeding device, and rotates in conjunction with the rotation of the spool, The tip detection sensor and the roller portion are arranged toward the axial center of the spool, The roller portion is positioned in a different location from the tip detection sensor in the circumferential direction of the roll paper. The aforementioned tip detection sensor is capable of detecting the step at the leading edge of the roll paper, The spool has a recess or protrusion on a part of its surface, The recess or protrusion is positioned to contact the tip detection sensor or the roller when the spool is installed in the paper feeding device and rotates without the paper and paper core on the spool. The control unit determines, based on the sensor signal from the tip detection sensor, whether or not there is a tip of the roll paper, and whether or not the roll paper is loaded onto the spool. A paper feeding device characterized by the following features.

2. The control unit determines the presence or absence of the tip of the roll paper by detecting the slope K1 of a graph representing the change in the output intensity of the sensor signal as the tip of the roll paper passes the roller part with respect to time, and the slope K2 of a graph representing the change in the output intensity of the sensor signal as the tip of the roll paper passes the tip detection sensor with respect to time. The paper feeding device according to feature 1.

3. The shape of the recess or the protrusion is determined such that the output intensity of the sensor signal of the tip detection sensor is greater than the output intensity of the sensor signal when detecting the tip of the maximum usable paper thickness. The control unit determines that the roll of paper is not loaded onto the spool if it detects an output intensity greater than the output intensity of the sensor signal when detecting the leading edge of the maximum usable paper thickness. The paper feeding device according to feature 2.

4. In the sensor signal of the tip detection sensor, when the tip of the paper with the maximum usable paper thickness passes the roller section, let K1max be the slope of the sensor signal, and when the tip of the paper with the maximum usable paper thickness passes the tip detection sensor, let K1max and K2max be determined in advance. The control unit determines that the roll paper is not provided on the spool if, in the sensor signal obtained by rotating the spool to be judged, it detects a slope with the same sign as K1max and whose absolute value is greater than K1max, and / or if it detects a slope with the same sign as K2max and whose absolute value is greater than K2max. The paper feeding device according to feature 1.

5. When KS is the larger of the value obtained by adding a predetermined tolerance to the absolute value of K1max and the value obtained by adding a predetermined tolerance to the absolute value of K2max, The control unit determines that the roll paper is not provided on the spool if it detects a slope in the sensor signal obtained by rotating the spool to be judged where the absolute value is greater than KS. The paper feeding device according to feature 4.

6. The recesses or protrusions are provided in two or more locations on the surface of the spool. The paper feeding device according to feature 1.

7. The control unit rotates the spool to be judged for a time equal to or longer than one rotation of the roll paper, determines whether or not there is a leading edge of the roll paper, and determines whether or not the roll paper is mounted on the spool. The paper feeding device according to feature 1.

8. A spool detection sensor that detects that the spool is mounted on the spool bearing base, It includes a display unit capable of displaying the paper feed screen, When the control unit detects that the spool is installed using the spool detection sensor, it rotates the spool to determine whether the roll paper is installed on the spool before displaying the paper feed screen on the display unit. If it determines that the roll paper is not installed on the spool, it does not display the paper feed screen on the display unit. The paper feeding device according to feature 1.

9. If the control unit determines that the roll paper is not loaded onto the spool, it will display a warning on the display unit. The paper feeding device according to feature 8.

10. The recess or protrusion is provided at both a position that contacts the tip detection sensor and a position that contacts the roller when the spool is installed in the paper feeding device and rotates without the paper and paper core on the spool. The control unit determines that the roll paper is not loaded onto the spool by detecting both the inclination of the sensor signal when the roller passes the recess or the protrusion, and the inclination of the sensor signal when the tip detection sensor passes the recess or the protrusion, as the spool rotates. The paper feeding device according to feature 1.

11. An image forming apparatus characterized by comprising a paper feeding device according to any one of claims 1 to 10.

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