JP7643173B2 - Paper feeder and image forming apparatus - Google Patents

Description

The present invention relates to a paper feeder and an image forming device.

A paper feeder that feeds rolled recording media such as roll paper rotates the set roll paper and continuously pays out the roll paper to the paper feed destination. In this type of paper feeder, a technology is known that automatically detects the leading edge of the roll paper after the roll paper is set, and pays out the detected leading edge to the paper feed destination.

For example, the paper feeder disclosed in Patent Document 1 detects the displacement of the outer circumferential surface of the rotating roll paper using a displacement change detection means (detection unit) that comes into contact with the roll paper, and determines the location where the largest displacement occurs as the leading edge of the roll paper.

However, in order to accurately detect the leading edge of the roll paper, this type of paper feeder must perform high-precision sampling by operating the detection unit at short sampling intervals while the roll paper is rotating, and the control unit must continue to evaluate this detection result. In other words, the paper feeder must continuously perform high-precision sampling until it detects the leading edge of the roll paper, imposing a heavy processing load.

Therefore, the objective is to provide a paper feeder and an image forming device that accurately detects the leading edge of a rolled recording medium while reducing the processing load.

According to one aspect of the present invention, in a paper feeding device including a rotation drive unit that rotates a rolled recording medium, a detection unit that detects the height position of an outer peripheral surface of the rolled recording medium while the rolled recording medium is rotating, and a control unit that performs a leading edge detection process that detects the leading edge of the rolled recording medium based on a detection signal from the detection unit, the control unit operates the detection unit at a first sampling interval at the start of the leading edge detection process to perform low-precision sampling to detect a detection point where the height position of the outer peripheral surface changes, and performs a second sampling interval shorter than the first sampling interval based on the detection point detected by the low-precision sampling. High-precision sampling is performed by operating the detection unit at pulling intervals, and it is determined whether the height position of the outer circumferential surface detected by the low-precision sampling is above a judgment threshold. The point where the height position of the outer circumferential surface is above the judgment threshold is identified as the detected point. Based on multiple plots obtained by sampling the detected point by the high-precision sampling, the slope at which the detected point descends is calculated. The angle of the slope is compared with an angle threshold. If the angle of the slope is above the angle threshold, it is determined that the detected point is not the tip of the rolled recording medium. If the angle of the slope is less than the angle threshold, it is determined that the detected point is not the tip of the rolled recording medium .

The above-mentioned paper feeder and image forming device can accurately detect the leading edge of a rolled recording medium while reducing the processing load.

1 is a schematic side view of a paper feeder according to a first embodiment. 11A and 11B are diagrams illustrating an example of detection of the outer circumferential surface of the roll body by a detection unit. 10 is a flowchart illustrating a first processing example of a control unit. 10 is a flowchart illustrating a second processing example of the control unit. FIG. 11 is a schematic side view of a paper feeder according to a second embodiment. 13 is a flowchart illustrating a third example of processing by the control unit. FIG. 11 is a schematic side view of a paper feeder according to a third embodiment. 13 is a flowchart illustrating a fourth processing example of the control unit. 13 is a schematic side view showing another form of roll paper in the paper feeder according to the third embodiment. FIG. 13 is a flowchart illustrating a fifth processing example of the control unit. 13 is a flowchart of a routine for one item in the fifth processing example. 13 is a flowchart of a multiple routine in the fifth processing example. FIG. 13 is a schematic side view of a paper feeder according to a fourth embodiment. 13 is a flowchart illustrating a part of a sixth processing example of the control unit. 13 is a flowchart illustrating another part of the sixth processing example of the control unit. FIG. 1 is an explanatory diagram showing an image forming apparatus to which a paper feeder according to first to fourth embodiments is applied.

Below, the mode for carrying out the invention will be described with reference to the drawings. The embodiment shown below is an example of a paper feeder for embodying the technical concept of the present invention, and the present invention is not limited to the embodiment shown below. Unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described below are intended as examples, and are not intended to limit the scope of the present invention thereto. Furthermore, the sizes and positional relationships of the components shown in the drawings may be exaggerated for clarity of explanation.

First Embodiment
Fig. 1 is a schematic side view of a paper feeding device 100 according to a first embodiment. As shown in Fig. 1, the paper feeding device 100 feeds a rolled recording medium such as paper (roll paper), cloth, other fibers, a resin sheet, or a resin film wound in a roll shape. Below, the paper feeding device 100 that feeds roll paper RP as a rolled recording medium will be representatively described. In the following, the part of the roll paper RP that is wound in a roll shape will be referred to as the roll body R1, and the part that is unwound from the roll body R1 by the paper feeding operation will be referred to as the unwound section R2.

The paper feeder 100 includes a rotation drive unit 1 that rotates the roll body R1, a detection unit 2 that contacts the outer peripheral surface CS of the roll body R1 to detect the height position of the outer peripheral surface CS, a separation claw unit 3 that separates the leading edge of the roll paper RP, and a transport guide unit 4 that guides the payout unit R2. The paper feeder 100 also includes a control unit 5 that controls the operation of the paper feeder 100.

In this description, the "height position of the outer peripheral surface CS" refers to the height in the radial direction (normal direction, thickness direction of the roll paper RP) of the outer peripheral surface CS of the roll body R1, which has a circular shape in side view. Immediately after the roll paper RP is set in the paper feeder 100, the height position of the outer peripheral surface CS is approximately constant in the circumferential direction of the roll body R1. However, the height position of the outer peripheral surface CS displaces in the radial direction due to the step between the upper and lower layers of paper that occurs at the tip rt of the roll paper RP, and the bending (protrusion) or undulation of the roll paper RP, etc.

The rotation drive unit 1 includes a motor 10, a drive transmission unit 11 connected to a rotating shaft 10a of the motor 10, and a shaft unit 12 connected to the drive transmission unit 11 and on which the roll paper RP is directly attached (set). The rotation drive unit 1 can selectively rotate the roll body R1 in the direction of arrow A (clockwise direction in FIG. 1) and the direction of arrow B (counterclockwise direction in FIG. 1).

The motor 10 is capable of controlling the rotation angle or rotation speed and rotating the rotating shaft 10a forward and backward. The rotation drive unit 1 connects the motor 10 to the control unit 5 via a driver, and rotates the rotating shaft 10a of the motor 10 by supplying power from the driver under the control of the control unit 5. The drive transmission unit 11 is made up of gears, pulleys, belts, etc., and transmits the rotational driving force of the rotating shaft 10a of the motor 10 to the shaft unit 12. The shaft unit 12 is located at the center axis of the roll body R1, and the core of the roll body R1 is removably attached to its outer circumferential surface.

The rotation drive unit 1 may be equipped with a rotation detection sensor that detects the rotation angle and rotation speed of the roll body R1 or the shaft portion 12. The control unit 5 can perform feedback control of the rotation drive unit 1 using the detection signal of the rotation detection sensor. Furthermore, the control unit 5 stores the rotation angle of the roll body R1 and the circumferential position of the outer peripheral surface CS (for example, at the detected point where the height position of the outer peripheral surface CS has been displaced) at an appropriate timing based on the detection signal of the rotation detection sensor. The detection unit 2 may be used as the rotation detection sensor. Furthermore, the rotation drive unit 1 is not limited to the above configuration. For example, the rotation drive unit 1 may be equipped with a payout roller that contacts the outer peripheral surface CS of the roll body R1, and the roll body R1 may be rotated by rolling the payout roller with the motor 10.

The detection unit 2 includes a contactor 20 that contacts the outer peripheral surface CS of the roll body R1, a support 21 that supports the contactor 20, an elastic body 22 that presses the contactor 20 against the roll body R1 via the support 21, and a sensor body 23 that detects the displacement of the support 21.

The contact 20 is formed in a cylindrical or disc shape, and is rotatably supported at one end of the support 21. The contact 20 receives an appropriate pressing force from the support 21 and comes into contact with the outer peripheral surface CS of the roll body R1, and rolls on the outer peripheral surface CS as the roll body R1 rotates. For example, the contact 20 comes into contact with the outer peripheral surface CS at a position slightly shifted toward the arrow X1 side with respect to the outer peripheral surface CS of the roll body R1 located at the lowest end in the vertical direction of the shaft portion 12 (gravity direction: arrow Z direction in Figure 1).

The height position of the contact 20 is maintained or displaced depending on the height position of the outer peripheral surface CS during rotation of the roll body R1. If there is a convex portion c on the outer peripheral surface CS of the roll body R1 due to factors such as the leading end rt of the roll paper RP, or the warping or swell of the roll paper RP, the contact 20 displaces depending on the convex portion c. Note that in FIG. 1, the leading end rt of the roll paper RP and the warping ce occurring on the outer peripheral surface CS of the roll body R1, which are factors that cause the convex portion c, are shown in an exaggerated manner to make the present invention easier to understand.

On the other hand, the support 21 is formed in a rod shape that extends linearly for a predetermined length from one end supporting the contact 20 to the other end, and the sensor body 23 is arranged on the other end side. The support 21 is rotatably supported by a fulcrum 24 in a position near the contact 20 (closer to the one end than the middle position in the extension direction of the support 21). The elastic body 22 is provided, for example, between the fulcrum 24 and the other end of the support 21, and serves as a force point that elastically pulls the support 21, thereby pressing one end of the support 21 (contact 20) toward the outer circumferential surface CS of the roll body R1. In addition, the support 21 amplifies the change in the height position of the contact 20 pressed by the elastic body 22 (displacement of the outer circumferential surface CS) starting from the fulcrum 24 and transmits it to the other end of the support 21.

The sensor body 23 is a displacement sensor capable of detecting the displacement of the other end of the support 21. Examples of displacement sensors include an encoder, a scale sensor, and a micrometer. The sensor body 23 is communicatively connected to the control unit 5, detects the position of the other end of the support 21 in response to a detection command (including a bias voltage) from the control unit 5, and transmits the detection signal to the control unit 5. The control unit 5 appropriately processes the received detection signal to recognize the maintenance or displacement of the height position of the contact 20, i.e., the height position of the outer peripheral surface CS of the roll body R1.

The paper feeder 100 fixes the separation claw 3 at a position slightly offset toward the arrow X2 side with respect to the outer peripheral surface CS of the roll body R1 located at the vertically lowest end of the shaft 12 (a position sandwiching the vertical line of the shaft 12 with respect to the detection unit 2). The separation claw 3 has a separation end 3a that is acutely angled toward the arrow X1 side. When the roll paper RP (feed-out unit R2) rotates in the direction of the arrow B, the tip rt of the roll paper RP (feed-out unit R2) basically separates vertically downward from the outer peripheral surface CS of the roll body R1 due to its own weight. The separation claw 3 promotes the separation of the tip rt of the roll paper RP from the roll body R1. The separation claw 3 may have the separation end 3a in contact with the outer peripheral surface CS of the roll body R1, or may have the separation end 3a positioned at a position slightly separated from the outer peripheral surface CS of the roll body R1.

The transport guide section 4 is in the form of a plate capable of supporting the payout section R2 of the roll paper RP, and one end of the transport guide section 4 on the arrow X1 side is connected to the detection section 2. The transport guide section 4 extends at an angle from the detection section 2 toward the arrow X2 side and downward in the vertical direction, so that it intersects with the vertical direction of the shaft section 12 and is positioned at a predetermined distance vertically downward from the separation claw section 3. This transport guide section 4 can guide the tip rt of the payout section R2, which has separated from the outer peripheral surface CS of the roll body R1, so that it moves smoothly toward the arrow X2 side.

The control unit 5 includes one or more processors 50, a memory 51, an input/output interface, and an electronic circuit. The one or more processors 50 are a combination of one or more of a CPU, an ASIC, an FPGA, a circuit made of multiple discrete semiconductors, etc., and executes and processes a program stored in the memory 51. The memory 51 includes a non-volatile memory and a volatile memory, and forms a storage unit of the control unit 5. Note that a portion of the memory 51 may be built into the one or more processors 50.

The control unit 5 performs a leading edge detection process to determine the leading edge rt of the roll paper RP when the user sets the roll paper RP in the paper feed device 100 and before starting to feed the roll paper RP. For example, it is preferable that the control unit 5 automatically starts the leading edge detection process when it recognizes that the roll paper RP has been set.

In the leading edge detection process, the control unit 5 operates the rotation drive unit 1 to rotate the roll body R1 in the direction of arrow A (leading edge detection rotation direction). When the leading edge rt of the roll paper RP rotates in the direction of arrow A, it rotates along the outer peripheral surface CS of the roll body R1. While the roll body R1 is rotating, the control unit 5 detects the height position of the outer peripheral surface CS of the roll body R1 using the detection unit 2. The control unit 5 then associates the height position of the outer peripheral surface CS of the roll body R1 obtained from the detection unit 2 with the measured time information and stores them in the memory 51.

In addition, when the leading edge detection process starts, the control unit 5 first performs low-precision sampling to detect the height position of the outer peripheral surface CS at a long sampling interval (hereinafter referred to as the first sampling interval). The first sampling interval depends on the expected size of the convex portion c and the rotation speed of the roll body R1, but it is preferable to set it in the range of about 50 ms to 500 ms, for example. By detecting the height position of the outer peripheral surface CS at the first sampling interval, the control unit 5 can reduce the processing load.

Figure 2 illustrates the detection of the outer peripheral surface CS of the roll body R1 by the detection unit 2, where FIG. 2(a) shows the case where low-precision sampling and high-precision sampling are performed, and FIG. 2(b) shows the case where only low-precision sampling is performed. As shown in FIG. 2(a), while the roll body R1 is rotating, the control unit 5 detects a period during which the height position of the outer peripheral surface CS remains roughly constant, and a period during which the height position of the outer peripheral surface CS rises and falls according to the convex portion c of the outer peripheral surface CS. That is, the detection signal (height position of the outer peripheral surface CS) detected by the detection unit 2 shows a mountain-shaped shape that rises once at the convex portion c of the outer peripheral surface CS, and then falls once it passes the top of the convex portion c.

Therefore, the control unit 5 determines the convex portion c where the height position of the outer peripheral surface CS is high based on the detection signal obtained by low-precision sampling. For example, the control unit 5 stores in the memory 51 a judgment threshold Th for determining the convex portion c occurring on the outer peripheral surface CS of the roll body R1, and compares the height position of the outer peripheral surface CS with the judgment threshold Th. Then, when the height position of the outer peripheral surface CS is less than the judgment threshold Th, the control unit 5 determines that the convex portion c has not occurred on the outer peripheral surface CS, and when the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold Th, the control unit 5 determines that the convex portion c has occurred on the outer peripheral surface CS.

The judgment threshold Th for judging the height position of the outer peripheral surface CS may be a fixed value or a variable value. For example, the control unit 5 may set the judgment threshold Th based on at least one of the parameters of past sampling data, paper type, temperature, and humidity. The past sampling data is the detection result when the tip of the roll paper RP was detected in the past, and the displacement amount and displacement time of the detected point Dc. The paper type is the type of roll paper RP (including differences in thickness, number of rolls, and width). The temperature is the temperature of the surrounding environment of the paper feeder, and the paper feeder is equipped with a temperature sensor and detects the temperature. The humidity is the humidity of the surrounding environment of the paper feeder or the set position of the roll paper RP, and the paper feeder is equipped with a humidity sensor and detects the humidity. The control unit 5 has multiple judgment thresholds Th or correction values associated with these parameters, and sets the judgment threshold Th based on the judgment threshold Th or correction value of the parameter close to the condition of the roll paper RP to be actually detected.

However, the convex portion c that occurs on the outer peripheral surface CS of the roll body R1 is caused not only by the leading edge rt of the roll paper RP, but also by the deflection ce and undulations that occur on the outer peripheral surface CS of the roll body R1. In other words, the control unit 5 cannot determine whether the convex portion c is caused by the leading edge rt of the roll paper RP or a factor other than the leading edge rt just by recognizing the convex portion c based on the height position of the outer peripheral surface CS being equal to or greater than the judgment threshold value Th. For this reason, the control unit 5 performs a detailed analysis of the height position of the outer peripheral surface CS at the point where the convex portion c was detected to determine whether it is the leading edge rt of the roll paper RP.

Specifically, the control unit 5 performs high-precision sampling to detect the height position of the outer circumferential surface CS at a sampling interval (hereinafter referred to as the second sampling interval) shorter than the first sampling interval for the detection location Dc of the convex portion c detected by the low-precision sampling. The second sampling interval depends on the expected size of the convex portion c and the rotation speed of the roll body R1, but may be set to a range of about 1/10 to 1/2 of the first sampling interval, for example.

The control unit 5 continues this high-precision sampling until the cause of the convex portion c is determined by the process described below. The period during which high-precision sampling is performed may be set to a predetermined period from the timing when the height position of the outer peripheral surface CS becomes equal to or greater than the judgment threshold Th. The predetermined period is the period during which the height position of the outer peripheral surface CS of the convex portion c is in a generally lowered position, and may be determined by experiment or simulation. Alternatively, the period during which high-precision sampling is performed may be set to include a surplus period from the timing when the height position of the outer peripheral surface CS that became equal to or greater than the judgment threshold Th becomes less than the judgment threshold Th again.

When the control unit 5 determines that the height position of the outer peripheral surface CS is equal to or greater than the determination threshold Th while performing low-precision sampling, it switches to high-precision sampling. In high-precision sampling, the control unit 5 detects the height position of the outer peripheral surface CS at the second sampling interval, thereby enabling detailed recognition of changes in the height position of the outer peripheral surface CS at the convex portion c.

In other words, if a deflection ce or swell occurs on the outer peripheral surface CS, the height position of the outer peripheral surface CS decreases at a gentle slope as it descends from the top of the convex portion c. On the other hand, if the convex portion c is the leading edge rt of the roll paper RP, the height position of the outer peripheral surface CS decreases at a steep slope as it descends from the top of the convex portion c. Therefore, by capturing the slope of the point where the height position of the outer peripheral surface CS descends from the top of the convex portion c, it is possible to distinguish between the leading edge rt of the roll paper RP and the deflection or swell of the outer peripheral surface CS.

For example, the control unit 5 connects the plots of the height positions of the outer peripheral surface CS detected by high-precision sampling to virtually form a continuous change line, and compares the inclination angle θ of the change line as it descends from the apex of the convex portion c with an angle threshold value Tθ pre-stored in the memory 51. As an example, the inclination angle θ is set to the inclination of the tangent line at the point where the change line intersects with the judgment threshold value Th. If the inclination angle θ of the change line is equal to or greater than the angle threshold value Tθ, the control unit 5 determines that the change line is the leading edge rt of the roll paper RP, and if the inclination angle θ of the change line is less than the angle threshold value Tθ, the control unit 5 determines that the change line is due to a deflection ce or swell of the outer peripheral surface CS of the roll paper RP (a factor other than the leading edge rt of the roll paper RP).

Here, referring to the detection result of the detection unit 2 using only low-precision sampling shown in FIG. 2(b), it can be said that even if the control unit 5 recognizes that the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold Th, there is a possibility that the shape of the descending portion of the convex portion c may be overlooked due to low-precision sampling. In other words, by combining low-precision sampling and high-precision sampling, the control unit 5 is able to accurately detect the height position of the outer peripheral surface CS as shown in FIG. 2(a).

The determination of whether the tip rt of the roll paper RP is the tip rt of the roll paper RP is not limited to the inclination when the height position of the detected outer peripheral surface CS changes. As an example, the control unit 5 may measure the time length from the timing when the height position of the outer peripheral surface CS becomes equal to or greater than the judgment threshold Th to the timing when the height position of the outer peripheral surface CS becomes less than the judgment threshold Th, and compare the time length with a pre-stored time threshold. The control unit 5 may determine that the tip rt of the roll paper RP is the tip rt of the roll paper RP when the time length is less than the time threshold, while determining that a factor other than the tip rt of the roll paper RP is the tip rt of the roll paper RP when the time length is equal to or greater than the time threshold. Alternatively, the reference shape of the change line corresponding to the tip rt of the roll paper RP (or the reference shape of the deflection or swell of the outer peripheral surface CS) may be obtained by experiment or the like, and the control unit 5 may correlate the shape of the change line of the outer peripheral surface CS during the implementation period of high-precision sampling with the reference shape. For example, the control unit 5 calculates the correlation coefficient between the shape of the change line of the outer peripheral surface CS and the reference shape of the tip rt of the roll paper RP, and if the correlation coefficient is equal to or greater than a predetermined coefficient, it determines that the tip rt of the roll paper RP is the cause, and if the correlation coefficient is less than the predetermined coefficient, it determines that the cause is a factor other than the tip rt of the roll paper RP.

When the control unit 5 determines the leading edge rt of the roll paper RP, it ends the leading edge detection process. Then, the control unit 5 rotates the roll body R1 in the direction of the arrow A using the rotation drive unit 1, and places the detected leading edge rt of the roll paper RP on the outer peripheral surface CS of the vertically lowermost end of the shaft unit 12. The leading edge rt of the roll paper RP moves away from the outer peripheral surface CS of the roll body R1 due to its own weight. Then, the paper feeder 100 rotates the roll body R1 in the direction of the arrow B (paper feed rotation direction) to start the paper feed operation of the roll paper RP. When the roll paper RP rotates in the direction of the arrow B, the leading edge rt of the roll paper RP moves away from the outer peripheral surface CS of the roll body R1 on the vertically lower side of the roll paper RP. At this time, the separation claw unit 3 may separate the leading edge of the roll paper RP. This allows the paper feeder 100 to smoothly send out the unwinding portion R2 of the roll paper RP between the separation claw unit 3 and the transport guide unit 4.

The paper feeder 100 according to this embodiment is basically configured as described above, and the process flow of the leading edge detection process of the control unit 5 will be described in detail below.

Figure 3 is a flowchart showing a first processing example of the control unit 5. As shown in Figure 3, when the control unit 5 of the paper feeder 100 starts the leading edge detection process, it first operates the rotation drive unit 1 to rotate the roll paper RP in the direction of arrow A (step S10).

Then, while the roll paper RP is rotating in the direction of arrow A, the control unit 5 performs low-precision sampling to detect the height position of the outer peripheral surface CS of the roll body R1 at a first sampling interval using the detection unit 2 (step S11).

In this low-precision sampling, the control unit 5 determines whether the height position of the outer peripheral surface CS of the roll body R1 is equal to or greater than the judgment threshold Th (step S12). If the height position of the outer peripheral surface CS is less than the judgment threshold Th (step S12: NO), the control unit 5 returns to step S11 and repeats the same process. On the other hand, if the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold Th (step S12: YES), the control unit 5 proceeds to step S13.

In step S13, the control unit 5 performs high-precision sampling to detect the height position of the outer peripheral surface CS of the roll body R1 at the second sampling interval using the detection unit 2.

In this high-precision sampling, the control unit 5 judges whether the inclination angle θ of the outer peripheral surface CS of the convex portion c that exceeds the judgment threshold Th is equal to or greater than the angle threshold Tθ (step S14). If the inclination angle θ is less than the angle threshold Tθ (step S14: NO), the convex portion c captured by the high-precision sampling is the cause of the deflection or waviness of the outer peripheral surface CS. Therefore, the control unit 5 returns to step S11 and performs low-precision sampling again.

On the other hand, if the tilt angle θ is equal to or greater than the angle threshold Tθ (step S14: YES), the convex portion c captured by high-precision sampling is the leading edge rt of the roll paper RP. Therefore, the control unit 5 proceeds to step S15, stores the determined circumferential position of the leading edge rt of the roll paper RP in the memory 51, and places the leading edge rt of the roll paper RP on the outer peripheral surface CS of the vertically lowest end of the shaft portion 12 (step S15).

When feeding paper from the paper feeder 100, the control unit 5 operates the rotation drive unit 1 to rotate the roll paper RP in the direction of arrow B. This allows the paper feeder 100 to smoothly guide the leading edge rt of the roll paper RP, which has separated from the roll body R1, to the transport guide unit 4.

As described above, the paper feeder 100 captures the change in the height position of the outer peripheral surface CS of the roll body R1 by low-precision sampling while the roll body R1 rotates once in the direction of arrow A, and performs high-precision sampling at that timing. This allows the paper feeder 100 to accurately detect the leading edge rt of the roll paper RP while reducing the processing load on the control unit 5.

The operation of the sheet feeding device 100 is not limited to the above process flow, and various modifications are possible. For example, the sheet feeding device 100 may continue low-precision sampling during the first rotation of the roll body R1 in the direction of arrow B, and perform high-precision sampling from the second rotation onwards for one or more detection points Dc where the height position of the outer circumferential surface CS is equal to or greater than the judgment threshold value Th. The process flow of the control unit 5 in this case will be described below with reference to FIG. 4. FIG. 4 is a flowchart showing a second processing example of the control unit 5.

The control unit 5 of the paper feeder 100 performs the same processes as steps S10 to S12 in FIG. 3 from step S20 to step S22 of the second processing example shown in FIG. 4. Then, when the height position of the outer peripheral surface CS becomes equal to or greater than the judgment threshold value Th (step S22: YES), the control unit 5 stores the detected point Dc of the outer peripheral surface CS of the roll body R1 that becomes equal to or greater than the judgment threshold value Th in the memory 51 (step S23).

Then, the control unit 5 determines whether the first rotation of the roll body R1 has been completed (one revolution) (step S24). If the first rotation of the roll body R1 has not been completed (step S24: NO), the control unit 5 returns to step S21 and repeats the same process flow. On the other hand, if the first rotation of the roll body R1 has been completed (step S24: YES), the control unit 5 proceeds to step S25, where the control unit 5 stops detecting the height position of the outer circumferential surface CS of the roll body R1 by low-precision sampling. At this time, the control unit 5 moves to the second rotation of the roll body R1.

During the second rotation, the control unit 5 determines whether the detection unit 2 has reached the vicinity of the detection point Dc where the height position of the outer peripheral surface CS during the first rotation was equal to or greater than the judgment threshold value Th (step S26). If the detection unit 2 has not reached the vicinity of the detection point Dc (step S26: NO), the control unit 5 repeats step S26, whereas if the detection unit 2 has reached the vicinity of the detection point Dc (step S26: YES), the control unit 5 proceeds to step S27.

In step S27, the control unit 5 performs high-precision sampling to detect the height position of the outer peripheral surface CS of the roll body R1 at the second sampling interval using the detection unit 2.

In this high-precision sampling, the control unit 5 judges whether the inclination angle θ of the outer peripheral surface CS of the convex portion c that exceeds the judgment threshold Th is equal to or greater than the angle threshold Tθ (step S28). If the inclination angle θ is less than the angle threshold Tθ (step S28: NO), the control unit 5 returns to step S25 and repeats the same process flow. On the other hand, if the inclination angle θ is equal to or greater than the angle threshold Tθ (step S28: YES), the control unit 5 proceeds to step S29. Then, the control unit 5 stores the determined circumferential position of the leading edge rt of the roll paper RP in the memory 51, and places the leading edge rt of the roll paper RP on the outer peripheral surface CS of the lowermost end of the shaft 12 in the vertical direction (step S29). Thereafter, when the paper feeder 100 is to feed the paper, the control unit 5 operates the rotation drive unit 1 to rotate the roll paper RP in the direction of the arrow B.

As described above, the paper feeder 100 performs low-precision sampling during the first rotation of the roll body R1, and then performs high-precision sampling of the detection location Dc during the second and subsequent rotations of the roll body R1. Even in this case, the paper feeder 100 can reduce the processing load and accurately detect the leading edge rt of the roll paper RP.

Second Embodiment
Fig. 5 is a schematic side view of a sheet feeding device 100A according to the second embodiment. As shown in Fig. 5, the sheet feeding device 100A may be configured to have two sensors (a low-precision detection unit 2A that performs low-precision sampling and a high-precision detection unit 2B that performs high-precision sampling) separately as the detection unit 2. Note that the configuration of the sheet feeding device 100A other than the detection unit 2 is the same as the configuration of the sheet feeding device 100 according to the first embodiment, and detailed description thereof will be omitted (the same applies to the following embodiments).

Specifically, the low-precision detection unit 2A is provided vertically above the separation claw portion 3 and on the arrow X1 side of the separation claw portion 3 (the side farther away from the shaft portion 12 than the separation claw portion 3 along the horizontal direction). The low-precision detection unit 2A is connected to the control unit 5, and upon receiving a detection command from the control unit 5, detects the height position of the outer circumferential surface CS of the roll body R1 at a first sampling interval and transmits the detection signal to the control unit 5.

On the other hand, the high-precision detection unit 2B is provided at the same position as the detection unit 2 according to the first embodiment. That is, the high-precision detection unit 2B is provided at a position slightly shifted toward the arrow X1 side with respect to the outer peripheral surface CS of the lowermost end of the shaft portion 12 in the vertical direction (gravity direction). The high-precision detection unit 2B is connected to the control unit 5, and upon receiving a detection command from the control unit 5, detects the height position of the outer peripheral surface CS of the roll body R1 at the second sampling interval and transmits the detection signal to the control unit 5. The low-precision detection unit 2A and the high-precision detection unit 2B may be the same type of sensor, or different types of sensors (for example, the high-precision detection unit 2B having a higher resolution than the low-precision detection unit 2A) may be applied.

The paper feeder 100A according to the second embodiment is basically configured as described above, and the flow of the leading edge detection process by the control unit 5 will be described below.

Figure 6 is a flowchart showing a third processing example of the control unit 5. As shown in Figure 6, when the control unit 5 of the paper feeder 100A starts the leading edge detection process, it first operates the rotation drive unit 1 to rotate the roll paper RP in the direction of arrow A (step S30).

Then, while the roll paper RP is rotating in the direction of arrow A, the control unit 5 performs low-precision sampling to detect the height position of the outer peripheral surface CS of the roll body R1 at a first sampling interval using the low-precision detection unit 2A (step S31).

In this low-precision sampling, the control unit 5 determines whether the height position of the outer peripheral surface CS of the roll body R1 is equal to or greater than the judgment threshold Th (step S32). If the height position of the outer peripheral surface CS is less than the judgment threshold Th (step S32: NO), the control unit 5 returns to step S31 and repeats the same process. On the other hand, if the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold Th (step S32: YES), the control unit 5 stores the circumferential position of the outer peripheral surface CS equal to or greater than the judgment threshold Th in the memory 51 as the detection point Dc, and proceeds to step S33.

In step S33, the control unit 5 performs high-precision sampling using the high-precision detection unit 2B for the detection location Dc where the height position of the outer circumferential surface CS detected by the low-precision detection unit 2A is equal to or greater than the judgment threshold value Th. During this time, the low-precision detection unit 2A continues low-precision sampling.

In this high-precision sampling, the control unit 5 judges whether the inclination angle θ of the outer peripheral surface CS of the convex portion c exceeding the judgment threshold Th is equal to or greater than the angle threshold Tθ (step S34). If the inclination angle θ is less than the angle threshold Tθ (step S34: NO), the control unit 5 proceeds to step S35. In step S35, the control unit 5 stops detection (high-precision sampling) by the high-precision detection unit 2B, returns to step S32, and repeats the same processes thereafter.

On the other hand, if the inclination angle θ is equal to or greater than the angle threshold Tθ (step S34: YES), the convex portion c captured by high-precision sampling is the leading edge rt of the roll paper RP. Therefore, the control unit 5 proceeds to step S36 and stops detection by the low-precision detection unit 2A and the high-precision detection unit 2B. The control unit 5 also stores the determined circumferential position of the leading edge rt of the roll paper RP in the memory 51, and places the leading edge rt of the roll paper RP at the vertical lower end of the shaft unit 12 (step S37). Then, when feeding the paper feeder 100A, the control unit 5 operates the rotation drive unit 1 to rotate the roll paper RP in the direction of the arrow B. This allows the paper feeder 100A to smoothly guide the leading edge rt of the roll paper RP separated from the roll body R1 to the transport guide unit 4.

As described above, even with a configuration including a low-precision detection unit 2A and a high-precision detection unit 2B, the paper feeder 100A can accurately detect the leading edge rt of the roll paper RP while reducing the processing load. In particular, the paper feeder 100A performs low-precision sampling with the low-precision detection unit 2A on the upstream side in the direction of the arrow A, and then performs high-precision sampling with the high-precision detection unit 2B on the downstream side in the direction of the arrow A. This allows the paper feeder 100A to capture the displacement shape of the entire detection point Dc of the roll body R1 with greater accuracy. It goes without saying that the paper feeder 100A according to the second embodiment can also perform the second processing example described above (an operation in which low-precision sampling is performed on the first rotation and high-precision sampling is performed on the second rotation).

Third Embodiment
7 is a schematic side view of a paper feeder 100B according to the third embodiment. As shown in Fig. 7, the paper feeder 100B includes a transport guide 4 and an arrival detector 6. The controller 5 detects the leading edge rt of the roll paper RP based on a detection signal from the detector 2 and a detection signal from the arrival detector 6.

Specifically, the arrival detection unit 6 is provided vertically below the separation claw unit 3 and on the arrow X1 side of the transport guide unit 4. The arrival detection unit 6 can be, for example, a non-contact sensor such as an optical sensor, or a contact sensor that detects the roll paper RP based on whether or not the roll paper RP is in contact.

The control unit 5 continuously performs low-precision sampling from the start of the tip detection process, and performs control to switch to high-precision sampling as necessary based on the detection result of the reach detection unit 6. FIG. 8 is a flowchart showing a fourth processing example of the control unit 5. Below, an example of tip detection processing of the control unit 5 using the reach detection unit 6 will be described with reference to FIG. 8.

The control unit 5 of the paper feeder 100B performs the same processes as steps S10 to S12 in FIG. 3 from step S40 to step S42 of the fourth processing example. That is, after the start of the leading edge detection process, the control unit 5 monitors the change in the height position of the outer peripheral surface CS of the roll paper RP by low-precision sampling. Then, when the height position of the outer peripheral surface CS becomes equal to or greater than the judgment threshold value Th (step S42: YES), the control unit 5 rotates the roll body R1 in the direction of arrow A, and positions the detection point Dc equal to or greater than the judgment threshold value Th on the outer peripheral surface CS at the vertically lowest end of the shaft portion 12 (step S43).

Then, the control unit 5 rotates the rotation drive unit 1 in the reverse direction to rotate the roll body R1 in the direction of arrow B (step S44).

During the rotation of the roll body R1 in the direction of arrow B, the control unit 5 determines whether the tip rt of the payout unit R2 has reached the arrival detection unit 6 (step S45). Here, if the detected point Dc detected by low-precision sampling is the tip rt of the payout unit R2, the arrival detection unit 6 detects the tip rt of the payout unit R2 moving along the transport guide within a predetermined time. Therefore, when the arrival detection unit 6 detects the tip rt of the payout unit R2 (step S45: YES), the control unit 5 ends the tip detection process and proceeds directly to the paper feed operation of the roll paper RP.

On the other hand, if the detected point Dc detected by low-precision sampling is a deflection or undulation of the outer peripheral surface CS, the arrival detection unit 6 will not detect the tip rt of the payout portion R2. Therefore, if the arrival detection unit 6 does not detect the tip rt of the payout portion R2 within a predetermined time (step S45: NO), the control unit 5 proceeds to step S46 and rotates the roll body R1 again in the direction of arrow A. Then, while the roll body R1 is rotating in step S46, the control unit 5 performs high-precision sampling (step S47).

When high-precision sampling is performed, there is a location where the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold value Th before the arrival of the previously detected detection point Dc. Therefore, the control unit 5 determines whether the inclination angle θ of the outer peripheral surface CS is equal to or greater than the angle threshold value Tθ for the location where the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold value Th in high-precision sampling (step S48). If the inclination angle θ is less than the angle threshold value Tθ (step S48: NO), the control unit 5 returns to step S47 and continues high-precision sampling.

On the other hand, if the tilt angle θ is equal to or greater than the angle threshold Tθ (step S48: YES), the control unit 5 proceeds to step S49. In step S49, the control unit 5 stores the determined circumferential position of the leading edge rt of the roll paper RP in the memory 51, and positions the leading edge rt of the roll paper RP at the vertical bottom end of the shaft portion 12.

As described above, the paper feeder 100B may be configured to perform paper feed operations by taking advantage of low-precision sampling, and to perform high-precision sampling if it determines that an abnormality exists in which the leading edge rt of the roll paper RP is not being transported to the transport guide section 4. In particular, when using roll paper RP that is less prone to bending ce or undulation, the paper feeder 100B can efficiently perform the paper feed operation of the roll paper RP. It should be noted that the paper feeder 100B according to the third embodiment can of course also perform the first and second processing examples described above.

Figure 9 is a schematic side view showing another form of roll paper RP in paper feeder 100B according to the third embodiment. As shown in Figure 9(a), the leading edge rt of roll paper RP set in paper feeder 100B may adhere to the outer peripheral surface CS of roll body R1 due to static electricity or the like, which may prevent it from being detected as a convex portion c by detector 2 and prevent it from being separated by separation claw 3. Note that Figure 9(a) illustrates a case where the leading edge rt of roll paper RP adheres to the outer peripheral surface CS and one convex portion c (flexion ce or undulation) occurs. On the other hand, Figure 9(b) illustrates a case where the leading edge rt of roll paper RP adheres to the outer peripheral surface CS and multiple convex portions c (flexion ce or undulation) occur.

Considering that the state shown in FIG. 9(a) or FIG. 9(b) may occur, it is preferable that the control unit 5 issues a warning and stops the paper feed operation if the leading edge rt cannot be detected for a long time based on the detection signal from the detection unit 2 and the detection signal from the reach detection unit 6. The process flow of the control unit 5 in this case will be described below with reference to FIG. 10 to FIG. 12. FIG. 10 is a flowchart showing a fifth processing example of the control unit 5. FIG. 11 is a flowchart of the single-item routine of the fifth processing example. FIG. 12 is a flowchart of the multiple-item routine of the fifth processing example.

The control unit 5 of the paper feeder 100B performs steps S50 to S52 of the fifth processing example, which are the same as steps S10 to S12 in FIG. 3. That is, after the start of the leading edge detection process, the control unit 5 monitors the change in the height position of the outer peripheral surface CS of the roll paper RP by low-precision sampling. Then, when the height position of the outer peripheral surface CS becomes equal to or greater than the judgment threshold value Th (step S52: YES), the control unit 5 stores the detected point Dc in the memory 51 (step S53).

The control unit 5 determines whether the first rotation of the roll body R1 has been completed (one revolution) (step S54). If the first rotation of the roll body R1 has not been completed (step S54: NO), the control unit 5 returns to step S51 and repeats the same process flow. On the other hand, if the first rotation of the roll body R1 has been completed (step S54: YES), the control unit 5 proceeds to step 55, where the control unit 5 determines whether the number of detected locations Dc is one or multiple (step S55). If there is one detected location Dc (step S55: YES), the control unit 5 performs the single-detection routine, and if there are multiple detected locations Dc (step S55: NO), the control unit 5 performs the multiple-detection routine.

In the single-item routine shown in FIG. 11, the control unit 5 rotates the roll paper RP in the direction of arrow A, and positions the detection point Dc of the roll paper RP on the outer peripheral surface CS of the vertically lowermost end of the shaft portion 12 (step S60). Next, the control unit 5 rotates the rotation drive unit 1 in the reverse direction, and rotates the roll body R1 in the direction of arrow B (step S61).

During this rotation of the roll body R1 in the direction of arrow B, the control unit 5 determines whether the leading edge rt of the unwinding part R2 has reached the arrival detection unit 6 (step S62). If the arrival detection unit 6 detects the leading edge rt of the unwinding part R2 (step S62: YES), the control unit 5 ends the leading edge detection process and proceeds directly to the feeding operation of the roll paper RP. On the other hand, if the arrival detection unit 6 does not detect the leading edge rt of the unwinding part R2 within a predetermined time (step S62: NO), the control unit 5 proceeds to step S63 and rotates the roll body R1 again in the direction of arrow A. Then, during the rotation of the roll body R1 in step S63, the control unit 5 performs high-precision sampling (step S64).

During high-precision sampling, the control unit 5 determines whether there is a location where the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold Th (step S65). If there is a location where the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold Th (step S65: YES), the control unit 5 determines whether the inclination angle θ of the outer peripheral surface CS is equal to or greater than the angle threshold Tθ for that location (step S66). If the inclination angle θ is less than the angle threshold Tθ (step S66: NO), the control unit 5 returns to step S65 and continues high-precision sampling. On the other hand, if the inclination angle θ is equal to or greater than the angle threshold Tθ (step S66: YES), the control unit 5 proceeds to step S67. In step S67, the control unit 5 stores the determined circumferential position of the leading edge rt of the roll paper RP in the memory 51, and places the leading edge rt of the roll paper RP on the outer peripheral surface CS at the vertically lowest end of the shaft portion 12 (step S67).

Conversely, if there is no point where the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold Th (step S65: NO), the control unit 5 determines that the leading edge rt of the roll paper RP is in contact with the outer peripheral surface CS. In this case, the control unit 5 outputs a warning via the notification unit (monitor, speaker, etc.) of the paper feeder 100B and stops the rotation of the roll paper RP (step S68). This allows the user of the paper feeder 100B to easily recognize that the leading edge rt of the roll paper RP is in contact with the outer peripheral surface CS.

In the multiple-unit routine shown in FIG. 12, the control unit 5 first determines whether the detection point Dc closest to the transport guide unit 4 is located downstream in the direction of arrow B (downstream in the direction of arrow A) (step S70). If the detection point Dc is located downstream in the direction of arrow B (step S70: YES), the control unit 5 rotates the roll body R1 in the direction of arrow A (step S71). On the other hand, if the detection point Dc is located downstream in the direction of arrow A (step S70: NO), the control unit 5 rotates the roll body R1 in the direction of arrow B (step S72).

The control unit 5 continuously performs high-precision sampling during rotation in the direction of arrow A or during rotation in the direction of arrow B (step S73).

Then, the control unit 5 judges whether there is a location where the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold Th (step S74). If there is a location where the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold Th (step S74: YES), the control unit 5 judges whether the inclination angle θ of the outer peripheral surface CS is equal to or greater than the angle threshold Tθ for that location (step S75). If the inclination angle θ of the outer peripheral surface CS is less than the angle threshold Tθ (step S74: NO), the control unit 5 returns to step S73 and repeats the same process flow. If the inclination angle θ is equal to or greater than the angle threshold Tθ (step S75: YES), the control unit 5 proceeds to step S76, stores the judged circumferential position of the leading edge rt of the roll paper RP in the memory 51, and places the leading edge rt of the roll paper RP at the circumferential position of the vertically lowest end of the shaft portion 12.

On the other hand, if there is no point where the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold Th (step S74: NO), the control unit 5 proceeds to step S77 and judges whether the roll paper RP being sampled with high accuracy has completed one revolution (step S77). If the roll paper RP has not completed one revolution (step S77: NO), the control unit 5 returns to step S73 and repeats the same process flow.

Conversely, if high-precision sampling of all detection points Dc is completed (step S77: YES), the leading edge rt of the roll paper RP cannot be found in all of the convex portions c that have appeared on the outer peripheral surface CS, meaning that the leading edge rt is in close contact with the outer peripheral surface CS. For this reason, the control unit 5 outputs a warning via the notification unit (monitor, speaker, etc.) of the paper feeder 100B and stops the rotation of the roll paper RP (step S78). This allows the user of the paper feeder 100B to easily recognize that the leading edge rt of the roll paper RP is in close contact.

As in the fifth processing example above, the control unit 5 can find the leading edge rt of the roll paper RP by performing high-precision sampling of the convex portion c of the outer peripheral surface CS. If the leading edge rt of the roll paper RP cannot be found even with high-precision sampling, the control unit 5 can output a warning to prompt the user to reset the roll paper RP or peel off the leading edge rt of the roll paper RP. The process of outputting a warning when the leading edge rt of the roll paper RP cannot be found can also be applied to the paper feeders 100 and 100A according to the first and second embodiments.

Fourth Embodiment
Fig. 13 is a schematic side view of a sheet feeding device 100C according to the fourth embodiment. As shown in Fig. 13, the sheet feeding device 100C has a detection unit 2 disposed at a position different from the position of the detection unit 2 of the sheet feeding device 100 according to the first embodiment. Furthermore, the sheet feeding device 100C includes a reach detection unit 6, similar to the sheet feeding device 100B according to the third embodiment.

Specifically, the paper feeder 100C has the detection unit 2 located on the X1 side of the roll paper RP and vertically above the center of the roll paper RP. Even when the detection unit 2 is located in this position, the detection unit 2 can detect the leading edge rt of the roll paper RP based on the change in thickness of the upper roll paper RP relative to the lower roll paper RP at the leading edge rt of the roll paper RP. In short, the location of the detection unit 2 that detects the height position of the outer circumferential surface CS of the roll paper RP is not particularly limited.

The control unit 5 according to this embodiment continues low-precision sampling during the first rotation in the leading edge detection process, and determines whether to perform a second rotation in the direction of arrow A or to rotate the roll paper RP in the direction of arrow B to unwind the unwinding portion R2 depending on the position of the detected point Dc at this time. Figure 14 is a flowchart showing a part of the sixth processing example of the control unit 5. Figure 15 is a flowchart showing the other part of the sixth processing example of the control unit 5.

The control unit 5 of the paper feeder 100C performs steps S80 to S82 of the sixth processing example shown in FIG. 14, which are the same as steps S10 to S12 in FIG. 3. That is, after the start of the leading edge detection process, the control unit 5 monitors the change in the height position of the outer peripheral surface CS of the roll paper RP by low-precision sampling. Then, when the height position of the outer peripheral surface CS becomes equal to or greater than the judgment threshold value Th (step S82: YES), the control unit 5 stores the detected point Dc in the memory 51 (step S83).

The control unit 5 determines whether the first rotation of the roll body R1 has been completed (one revolution) (step S84). If the first rotation of the roll body R1 has not been completed (step S84: NO), the control unit 5 returns to step S81 and repeats the same process flow. On the other hand, if the first rotation of the roll body R1 has been completed (step S84: YES), the control unit 5 proceeds to step 85.

In step S85, the control unit 5 determines whether or not there are multiple detected locations Dc. If there is one detected location Dc (step S85: NO), the control unit 5 executes the routine for one location shown in FIG. 11 (step S86). On the other hand, if there are multiple detected locations Dc (step S85: YES), the control unit 5 proceeds to step S87.

In step S87, it is determined whether or not there is a detected point Dc among the multiple detected points Dc that is closer to the transport guide section 4 than the detection section 2. If there is a detected point Dc that is closer to the transport guide section 4 than the detection section 2 (step S87: YES), it is more efficient to feed paper to the transport guide section 4 for that detected point Dc. Therefore, as shown in FIG. 15, the control section 5 places the detected point Dc that is closer to the transport guide section 4 on the outer peripheral surface CS at the vertically lowermost end of the shaft section 12 (step S88), and further rotates the roll paper RP in the direction of arrow B (step S89).

Then, the control unit 5 determines whether the leading edge rt of the payout unit R2 has reached the arrival detection unit 6 (step S90). If the arrival detection unit 6 detects the leading edge rt of the payout unit R2 (step S90: YES), the control unit 5 ends the leading edge detection process and proceeds directly to the paper feed operation of the roll paper RP. On the other hand, if the arrival detection unit 6 does not detect the leading edge rt of the payout unit R2 within a predetermined time (step S90: NO), the control unit 5 proceeds to step S91 and rotates the roll body R1 again in the direction of arrow A.

During the rotation of the roll body R1 in step S91, the control unit 5 performs high-precision sampling (step S92). When high-precision sampling is performed, there is a point where the height position of the outer circumferential surface CS is equal to or greater than the judgment threshold value Th before the arrival of the detection point Dc where the paper is fed. Therefore, the control unit 5 determines whether the inclination angle θ of the outer circumferential surface CS is equal to or greater than the angle threshold value Tθ for the point where the height position of the outer circumferential surface CS is equal to or greater than the judgment threshold value Th in the high-precision sampling (step S93).

If the tilt angle θ is less than the angle threshold Tθ (step S93: NO), the control unit 5 proceeds to step S94 and determines whether the roll paper RP has rotated one revolution in the second rotation. If the roll paper RP has not rotated one revolution (step S94: NO), the control unit 5 returns to step S92 and continues high-precision sampling. On the other hand, if the roll paper RP has rotated one revolution, the control unit 5 determines that it was unable to find the leading edge rt of the roll paper RP, and outputs a warning via the notification unit of the paper feeder 100C (step S95).

If the inclination angle θ is greater than or equal to the angle threshold value Tθ (step S93: YES), the control unit 5 proceeds to step S96, stores the determined circumferential position of the leading edge rt of the roll paper RP in the memory 51, and positions the leading edge rt of the roll paper RP at the vertical lower end of the shaft portion 12 (step S96).

Returning to step S87, if there is no detected location Dc closer to the transport guide unit 4 than the detection unit 2 (step S87: NO), the control unit 5 proceeds to step S97. In step S97, the control unit 5 performs high-precision sampling using the detection unit 2 while rotating the roll paper RP in the direction of arrow A from the beginning (while performing the second rotation).

In this high-precision sampling, the control unit 5 judges whether the inclination angle θ of the outer peripheral surface CS of the convex portion c exceeding the judgment threshold Th is equal to or greater than the angle threshold Tθ (step S98). If the inclination angle θ is less than the angle threshold Tθ (step S98: NO), the control unit 5 proceeds to step S97 and repeats the same process thereafter.

On the other hand, if the tilt angle θ is equal to or greater than the angle threshold Tθ (step S98: YES), the control unit 5 determines the leading edge rt of the roll paper RP and proceeds to step S99. The control unit 5 then positions the leading edge rt of the roll paper RP on the outer peripheral surface CS of the vertically lowest end of the shaft portion 12 (step S99).

In this way, the sheet feeding device 100C can increase the possibility of performing the sheet feeding operation early by changing the operation depending on the proximity of the detection unit 2 and the transport guide unit 4 for the detection point Dc detected by low-precision sampling. Note that the sixth processing example can also be applied to the sheet feeding devices 100, 100A, and 100B according to the first to third embodiments.

Figure 16 is an explanatory diagram showing an image forming apparatus 200 to which the paper feeders 100, 100A to 100C according to the first to fourth embodiments are applied. As shown in Figure 16, the image forming apparatus 200 has a conveying section 210, a first image forming section 220, a turn bar 230, a second image forming section 240, a sensor section 250, and a control device 260. While conveying the roll paper RP with the conveying section 210, the image forming apparatus 200 forms a full-color image on a first side of the roll paper RP with the first image forming section 220, and forms a full-color image on a second side of the roll paper RP opposite the first side with the second image forming section 240.

The transport section 210 has any one of the paper feeders 100, 100A-100C according to the first to fourth embodiments (paper feeder 100 will be described below as an example), as well as a winding section 211, and transports the unwinding section R2 of the roll paper RP. The paper feeder 100 unwinds the unwinding section R2 of the roll paper RP, and transports the unwinding section R2 by running it toward the first image forming section 220. The winding section 211 winds the unwinding section R2 around a rotated roll, and transports the unwinding section R2 from the second image forming section 240 toward the winding section 211.

The first image forming section 220 has a first liquid ejection unit 221 and a first drying unit 222. The first liquid ejection unit 221 ejects yellow (Y), magenta (M), cyan (C) and black (K) liquids individually. The first drying unit 222 dries the liquid applied to the first surface of the payout section R2 by rotating the first heating drum while contacting the second surface of the payout section R2 with the surface of the first heating drum that has a built-in heater. That is, the first image forming section 220 ejects liquid from the first liquid ejection unit 221 to the payout section R2 being transported based on image data input to the image forming device 200. Then, the liquid applied to the payout section R2 is dried by the first drying unit 222 to form a full-color image on the first surface of the payout section R2.

The turn bar 230 inverts the face of the payout section R2 after it is sent out from the outlet of the first drying unit 222, and sends the payout section R2 into the inlet of the second image forming section 240.

The second image forming section 240 has a second liquid ejection unit 241 and a second drying unit 242. The second liquid ejection unit 241 ejects yellow (Y), magenta (M), cyan (C) and black (K) liquids individually. The second drying unit 242 dries the liquid applied to the second surface of the payout section R2 by rotating the second heating drum while contacting the first surface of the payout section R2 with the surface of the second heating drum that has a built-in heater. That is, the second image forming section 240 ejects liquid from the second liquid ejection unit 241 to the payout section R2 being transported based on image data input to the image forming device 200. Then, the liquid applied to the payout section R2 is dried by the second drying unit 242 to form a full-color image on the second surface of the payout section R2.

The sensor unit 250 has a first transmissive optical sensor 251, a second transmissive optical sensor 252, and a third transmissive optical sensor 253, and outputs a detection signal according to the state of the payout section R2 being transported.

The control device 260 has a processor, memory, an electric circuit board, etc., and controls the conveying by the conveying unit 210 and the image forming operation of the first image forming unit 220 and the second image forming unit 240. For example, the control device 260 controls the conveying and stopping of the payout unit R2 by the conveying unit 210 based on the detection signals output by each of the first transmissive optical sensor 251, the second transmissive optical sensor 252, and the third transmissive optical sensor 253. The control device 260 may include the control unit 5 of the paper feeder 100, or may be provided separately from each other.

The image forming device 200 described above can form an image while transporting the feed section R2 by feeding the paper through the paper feeding operation of the paper feeder 100.

Although the embodiments have been described above, the present invention is not limited to the specifically disclosed embodiments above, and various modifications and variations are possible without departing from the scope of the claims.

As described above, by performing low-precision sampling at the start of the leading edge detection process, the paper feeder 100C is able to reduce the processing load while narrowing down the detection points Dc at which the height position of the outer peripheral surface CS of the roll paper RP changes. Then, by performing high-precision sampling based on the detection points Dc detected by low-precision sampling, the paper feeder 100C is able to accurately detect the leading edge rt of the roll paper RP.

The control unit 5 also determines whether the height position of the outer peripheral surface CS detected by low-precision sampling is equal to or greater than the judgment threshold Th, and identifies the location where the height position of the outer peripheral surface CS is equal to or greater than the judgment threshold Th as the detected location Dc. This allows the paper feeder 100 to easily extract the convex portion c where the height position of the outer peripheral surface CS is displaced.

The control unit 5 also calculates the slope of the descent of the detection point Dc based on multiple plots obtained by sampling the detection point Dc using high-precision sampling, and determines whether the detection point Dc is the leading edge rt of the roll paper RP based on the slope. This allows the paper feed device 100C to detect the leading edge rt of the roll paper RP with even greater accuracy.

The control unit 5 also sets the judgment threshold Th based on at least one of the past sampling data, paper type, temperature, and humidity parameters. This allows the control unit 5 to appropriately set the judgment threshold Th, and to more accurately determine the height position of the outer circumferential surface CS.

In addition, when the control unit 5 detects the detection point Dc by low-precision sampling, the control unit 5 immediately performs high-precision sampling on the detection point Dc. This allows the paper feed device 100C to shorten the time it takes to detect the leading edge rt of the roll paper RP.

The control unit 5 also performs low-precision sampling during the first rotation of the roll paper RP by the rotation drive unit 1, and performs high-precision sampling on the detection point Dc detected by the low-precision sampling during the first rotation and thereafter during the second rotation of the roll paper RP by the rotation drive unit 1. This allows the paper feeder 100C to detect the leading edge rt of the roll paper RP with even greater accuracy.

The detection unit 2 also includes a low-precision detection unit 2A that performs low-precision sampling and a high-precision detection unit 2B that performs high-precision sampling, and performs high-precision sampling on the detection point Dc detected by the low-precision detection unit 2A by the high-precision detection unit 2B. This allows the paper feeder 100C to operate the low-precision detection unit 2A and the high-precision detection unit 2B individually at appropriate times, allowing the detection point Dc to be monitored more accurately.

The device also includes an arrival detection unit 6 that detects when the roll paper RP reaches the transport guide unit 4 when the roll paper RP is fed. When the control unit 5 detects the detection point Dc during low-precision sampling, it starts a paper feeding operation to pay out the roll paper RP based on the detected detection point Dc before high-precision sampling, and if the arrival detection unit 6 does not detect the arrival of the roll paper RP after the paper feeding operation, it performs high-precision sampling. As a result, the paper feeding device 100C performs high-precision sampling when the roll paper RP does not reach the arrival detection unit 6, thereby improving the efficiency of the paper feeding operation of the roll paper RP.

Furthermore, when the control unit 5 detects multiple detection points Dc by performing low-precision sampling during the first rotation of the roll paper RP, it determines whether the detection point Dc is located closer to the transport guide unit 4 than the detection unit 2, and starts the paper feed operation if the detection point Dc is located closer to the transport guide unit 4 than the detection unit 2. If the arrival detection unit 6 does not detect the arrival of the roll paper RP after the paper feed operation, it performs high-precision sampling. This allows the paper feed device 100C to start feeding paper in a shorter time if the roll paper RP can be fed by the feeding operation of the detection point Dc that is closer to the transport guide unit 4 than the detection unit 2. On the other hand, if the roll paper RP cannot be fed, the paper feed device 100C can detect the leading edge rt of the roll paper RP by high-precision sampling.

The control unit 5 also starts the paper feeding operation when one detection point Dc is detected by performing low-precision sampling during the first rotation of the roll paper RP, and after the paper feeding operation, if the arrival detection unit 6 does not detect the arrival of the roll paper RP, it performs high-precision sampling. Even in this case, the paper feeding device 100C can start paper feeding in a shorter time.

In addition, when the control unit 5 detects multiple detection points Dc by performing low-precision sampling during the first rotation of the roll paper RP, it guides the detection point Dc closest to the transport guide unit 4 to the transport guide unit 4 to start the paper feeding operation, and if the arrival detection unit 6 does not detect the arrival of the roll paper RP after the paper feeding operation, it performs high-precision sampling. Even in this case, the paper feeding device 100C can accurately detect the leading edge rt of the roll paper RP while reducing the processing load.

Another aspect of the present invention is an image forming apparatus 200 having the above-mentioned paper feeder 100, 100A to 100C. The image forming apparatus 200 can stably transport the paper roll RP in the payout section R2 by accurately detecting the leading edge of the roll paper RP using the paper feeder 100, 100A to 100C.

REFERENCE SIGNS LIST 1 Rotational drive unit 10 Motor 11 Drive transmission unit 12 Shaft unit 2 Detection unit 2A Low-precision detection unit 2B High-precision detection unit 20 Contact 21 Support body 22 Elastic body 23 Sensor body 3 Separation claw unit 4 Transport guide unit 5 Control unit 50 Processor 51 Memory 6 Arrival detection unit c Convex portion ce Deflection CS Outer circumferential surface Dc Detection target location RP Roll paper R1 Roll body R2 Payout unit rt Tip

JP 2006-273446 A

Claims (12)

A rotation drive unit that rotates the roll-shaped recording medium;
a detection unit that detects a height position of an outer peripheral surface of the rolled recording medium while the rolled recording medium is rotating;
a control unit that performs a leading edge detection process to detect a leading edge of the rolled recording medium based on a detection signal from the detection unit,
The control unit is
At the start of the leading end detection process, the detection unit is operated at a first sampling interval to perform low-precision sampling to detect a detection point where a height position of the outer circumferential surface is displaced;
performing high-precision sampling by operating the detection unit at a second sampling interval that is shorter than the first sampling interval, based on the detection location detected by the low-precision sampling;
determining whether or not the height position of the outer circumferential surface detected by the low-precision sampling is equal to or greater than a determination threshold, and identifying a location where the height position of the outer circumferential surface is equal to or greater than the determination threshold as the detection location;
Based on a plurality of plots obtained by sampling the detected portion by the high-precision sampling, a slope at which the detected portion descends is calculated, the angle of the slope is compared with an angle threshold, and if the angle of the slope is equal to or greater than the angle threshold, it is determined that the detected portion is the leading end of the rolled recording medium, and if the angle of the slope is less than the angle threshold, it is determined that the detected portion is not the leading end of the rolled recording medium.
A paper feeding device characterized by: the detection unit includes a low-precision detection unit that performs the low-precision sampling and a high-precision detection unit that performs the high-precision sampling,
The high-precision detection unit performs the high-precision sampling on the detection target portion detected by the low-precision detection unit.
2. The paper feeder according to claim 1. a reach detection unit that detects the arrival of the rolled recording medium when the rolled recording medium is fed to a transport guide unit,
The control unit is
when the detection target portion is detected in the low-precision sampling, a paper feed operation for unwinding the roll-shaped recording medium based on the detected detection target portion is started prior to the high-precision sampling;
When the arrival detection unit does not detect the arrival of the roll-shaped recording medium after the paper feeding operation, the high-precision sampling is performed.
2. The paper feeder according to claim 1. 4. The paper feed device according to claim 1, wherein the control unit sets the determination threshold value based on at least one parameter selected from the group consisting of past sampling data, paper type, temperature, and humidity. The control unit is
5. The paper feeder according to claim 1, wherein when the detection portion is detected by the low-precision sampling, the high-precision sampling is immediately performed on the detection portion. A rotation drive unit that rotates the roll-shaped recording medium;
a detection unit that detects a height position of an outer peripheral surface of the rolled recording medium while the rolled recording medium is rotating;
a control unit that performs a leading edge detection process to detect a leading edge of the rolled recording medium based on a detection signal from the detection unit,
The control unit is
At the start of the leading end detection process, the detection unit is operated at a first sampling interval to perform low-precision sampling to detect a detection location where a height position of the outer circumferential surface is displaced during a first rotation of the rolled recording medium by the rotation drive unit;
a paper feeding device characterized in that, after the second rotation of the roll-shaped recording medium by the rotation drive unit, high-precision sampling is performed by operating the detection unit at a second sampling interval shorter than the first sampling interval for the detected location detected by the low-precision sampling in the first rotation. A rotation drive unit that rotates the roll-shaped recording medium;
a detection unit that detects a height position of an outer peripheral surface of the rolled recording medium while the rolled recording medium is rotating;
a control unit that performs a leading edge detection process to detect a leading edge of the rolled recording medium based on a detection signal from the detection unit,
The control unit is
At the start of the leading end detection process, the detection unit is operated at a first sampling interval to perform low-precision sampling to detect a detection point where a height position of the outer circumferential surface is displaced;
performing high-precision sampling by operating the detection unit at a second sampling interval that is shorter than the first sampling interval, based on the detection location detected by the low-precision sampling;
the detection unit includes a low-precision detection unit that performs the low-precision sampling and a high-precision detection unit that performs the high-precision sampling,
a high-precision detection section performing the high-precision sampling on the detection location detected by the low-precision detection section, A rotation drive unit that rotates the roll-shaped recording medium;
a detection unit that detects a height position of an outer peripheral surface of the rolled recording medium while the rolled recording medium is rotating;
a control unit that performs a leading edge detection process to detect a leading edge of the rolled recording medium based on a detection signal from the detection unit,
a reach detection unit that detects the arrival of the rolled recording medium when the rolled recording medium is fed to a transport guide unit,
The control unit is
At the start of the leading end detection process, the detection unit is operated at a first sampling interval to perform low-precision sampling to detect a detection point where a height position of the outer circumferential surface is displaced;
performing high-precision sampling by operating the detection unit at a second sampling interval that is shorter than the first sampling interval, based on the detection location detected by the low-precision sampling;
when the detection target portion is detected in the low-precision sampling, a paper feed operation for unwinding the roll-shaped recording medium based on the detected detection target portion is started prior to the high-precision sampling;
the high-precision sampling is performed when the arrival detection unit does not detect the arrival of the roll-shaped recording medium after the paper feeding operation. The control unit is
When a plurality of detection points are detected by performing the low-precision sampling during a first rotation of the roll-shaped recording medium, it is determined whether or not the detection point is located closer to the transport guide unit than the detection unit;
starting the paper feeding operation when the detected portion is located closer to the conveying guide portion than the detection portion;
9. The paper feeding device according to claim 8, wherein the high-precision sampling is performed when the arrival of the roll-shaped recording medium is not detected by the arrival detection unit after the paper feeding operation. The control unit is
when one of the detection points is detected by performing the low-precision sampling during a first rotation of the roll-shaped recording medium, the paper feeding operation is started;
9. The paper feeding device according to claim 8, wherein the high-precision sampling is performed when the arrival of the roll-shaped recording medium is not detected by the arrival detection unit after the paper feeding operation. The control unit is
When a plurality of detection points are detected by performing the low-precision sampling during a first rotation of the roll-shaped recording medium,
The detected portion closest to the transport guide portion is guided to the transport guide portion to start the paper feeding operation.
9. The paper feeding device according to claim 8, wherein the high-precision sampling is performed when the arrival of the roll-shaped recording medium is not detected by the arrival detection unit after the paper feeding operation. An image forming apparatus having a paper feeder according to any one of claims 1 to 11.

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