Sheet supply device and image forming apparatus

Abstract

To provide a sheet feeder for feeding a long sheet wound on a spool that determines reverse setting of a continuous sheet and can rewind the sheet delivered until determination.SOLUTION: A sheet feeder rotates a spool in a reverse direction by rotating means, determines whether the spool is set in a correct direction on a support part or set in a reverse direction on the basis of a first detection signal when a tip of a sheet passes a first sensor, and when the spool is set in the reverse direction, stops the motion of the rotating means.SELECTED DRAWING: Figure 15

Description

Technical Field

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

Background Art

[0002] There is known a sheet feeding device that supplies a continuous form sheet as a long sheet wound around a reel (spool). Further, there is known an image forming device that includes the sheet feeding device and forms an image on the supplied continuous form sheet. As a sheet feeding device, there is already known one that includes a sheet feeding mechanism in which after a user manually inserts the leading end (sheet leading end) of the continuous form sheet into the feeding unit, the device performs a sheet feeding operation after detecting the leading end.

[0003] In a conventional sheet feeding mechanism, there is known a technique of rotating a spool in the winding direction of a continuous form sheet, detecting the leading end of the sheet with a sensor, and after detecting the leading end, rotating the spool forward in the feeding direction of the continuous form sheet (for example, see Patent Document 1).

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique disclosed in Patent Document 1, the rotation in the winding direction of the continuous form sheet is referred to as reverse rotation, and the rotation in the feeding direction of the continuous form sheet is referred to as forward rotation. A sheet feeding mechanism applying the prior art cannot accurately detect the leading end of the sheet when the set direction of the spool is accidentally reversed (when reversely set), and the reverse rotation continues without stopping. As a result, the leading end of the continuous form sheet is fed out from the spool in the direction opposite to the feeding direction, causing problems such as damage.

[0005] An object of the present invention is to provide a technique for determining a reverse set of a continuous form sheet and rewinding the sheet fed out until the determination in a sheet feeding device that feeds a long sheet wound around a spool.

Means for Solving the Problems

[0006] To solve the above problems, one aspect of the present invention provides a support portion for supporting a roll formed by winding a long sheet onto a spool; a rotating means for rotating the roll supported by the support portion in a forward direction for unwinding the sheet and in a reverse direction for winding the sheet onto the roll; a guide member having a facing portion that faces the outer circumferential surface of the roll and a guide portion extending from the facing portion toward the forward direction for the sheet; a support shaft at the end of the guide member, with the downstream end in the forward direction as the pivot center, that rotatably supports the guide member in a direction that moves the facing portion toward or away from the outer circumferential surface; a biasing member that biases the rotation of the guide member toward the direction that moves the facing portion toward the roll; and a portion that protrudes from the facing portion toward the roll and on the outer circumferential surface of the roll. The device comprises: a first sensor biased in the direction of contact and outputting a first detection signal with a signal level corresponding to the amount of protrusion; a roller supported on the opposite side and contacting the outer surface of the roll at a position different from the first sensor in the circumferential direction of the roll; and a controller that controls the rotating means based on the signal change rate, which is the amount of change per unit time of the signal level of the first detection signal. The controller rotates the spool in the opposite direction using the rotating means, determines whether the spool is set in the correct orientation or in the wrong orientation at the support part based on the first detection signal when the leading edge of the sheet passes the first sensor, and stops the operation of the rotating means when the spool is set in the wrong orientation. [Effects of the Invention]

[0007] According to the present invention, in a sheet supply device that supplies a long sheet wound on a spool, it is possible to determine if the continuous sheet is set in the wrong direction and to rewind the sheet that has been unwound up to the time of the determination. [Brief explanation of the drawing]

[0008] [Figure 1] External perspective view of the image forming apparatus according to this embodiment. [Figure 2]A cross-sectional view showing the internal structure of an image forming apparatus. [Figure 3] Schematic diagram of the sheet supply device. [Figure 4] Perspective view of the guide arm. [Figure 5] A close-up view of the area surrounding the opposite side of a properly set continuous form sheet. [Figure 6] A diagram showing the positional relationship between the leading edge of a correctly set continuous sheet and the leading edge detection sensor and roller. [Figure 7] This diagram shows the change in the signal level of the detection signal from the tip detection sensor that detects the leading edge of a correctly set continuous sheet. [Figure 8] A close-up view of the area surrounding the opposite side of a properly set continuous form sheet. [Figure 9] This diagram shows the positional relationship between the leading edge of the inverted continuous sheet, the leading edge detection sensor, and the roller. [Figure 10] This diagram shows the change in the signal level of the detection signal from the tip detection sensor that detects the leading edge of a continuous sheet that is set up in reverse. [Figure 11] This diagram shows the first example of a problem that can occur when a continuous form sheet is inserted in reverse. [Figure 12] This diagram shows a second example of a problem that can occur when a continuous form sheet is inserted incorrectly. [Figure 13] This diagram illustrates a third example of a problem that can occur when continuous forms are inserted in reverse. [Figure 14] Hardware configuration diagram of the control block of an image forming apparatus. [Figure 15] A flowchart illustrating the first embodiment of the sheet setting process. [Figure 16] A flowchart illustrating a second embodiment of the sheet setting process. [Figure 17] A flowchart illustrating a third embodiment of the sheet setting process. [Figure 18] A flowchart showing a fourth embodiment of the sheet setting process. [Figure 19] A flowchart showing the fifth embodiment of the sheet setting process. [Figure 20]Flowchart showing a part of the sixth embodiment of the sheet set processing. [Figure 21] Flowchart showing another part of the sixth embodiment of the sheet set processing. [Figure 22] Diagram for explaining the conventional method of setting roll paper.

Modes for Carrying Out the Invention

[0009] [Embodiment of the Present Invention] Hereinafter, referring to FIGS. 1 and 2, the printer 1 as an embodiment of the image forming apparatus according to the present invention will be described. FIG. 1 is an external perspective view of the printer 1 according to the present embodiment. FIG. 2 is a cross-sectional view showing the internal structure of the printer 1.

[0010] [Overall Configuration of Printer 1] As shown in FIG. 1, the printer 1 as an embodiment of the image forming apparatus has an overall wide outer shape. A central cover 2 is provided at the central portion in the wide direction, and a right cover 3 and a left cover 4 are provided at both ends sandwiching the central cover 2. Further, side plates 5 are provided at the outer ends of the right cover 3 and the left cover 4, and an operation cover 6 that opens and closes with respect to the central cover 2 are provided. The outer shape of the housing of the printer 1 is formed by these respective covers (right cover 3, left cover 4, side plates 5, operation cover 6). Also, the printer 1 is supported by legs 7 provided near both ends in the longitudinal direction of the apparatus main body covered by the respective covers. Casters for facilitating movement are installed on the legs 7.

[0011] The printer 1 according to the present embodiment is an inkjet type image forming apparatus that discharges liquid ink onto a continuous accounting sheet P as a long sheet to form an image on the continuous accounting sheet P. However, the image forming method of the printer 1 is not limited to the inkjet method, and may be an electrophotographic method or the like.

[0012] As shown in Figure 2, the printer 1 mainly comprises a sheet supply unit 10, a transport unit 20, an image forming unit 30, a winding unit 40, and a controller 50 as a control unit, as an embodiment of the sheet supply device according to the present invention. The detailed configuration of the controller 50 will be described later with reference to Figure 14.

[0013] The sheet supply unit 10 supplies the continuous sheet P wound on the spool 8 (winding cylinder) to the transport unit 20 via the transport path L. In this specification, the direction in which the continuous sheet P is sent to the transport unit 20 in the sheet supply unit 10 is defined as the transport direction. The rotation of the spool 8 when the continuous sheet P is transported in the transport direction is defined as forward rotation. In addition, the rotation in the sheet supply unit 10 that moves the continuous sheet P in the opposite direction to the transport direction and winds it onto the spool 8 is defined as reverse rotation.

[0014] The transport path L is the space inside the printer 1 through which the continuous sheet P passes. More specifically, the transport path L is the route from the sheet supply unit 10 through the transport unit 20 and the image forming unit 30 to the winding unit 40. Details of the sheet supply unit 10 will be described later with reference to Figures 2 to 10.

[0015] The transport unit 20 transports the continuous sheet P supplied from the sheet supply unit 10 through the transport path L to the winding unit 40, passing through a position facing the image forming unit 30. The transport unit 20 mainly comprises a transport roller 21, a pressure roller 22, and a transport motor 23. The transport roller 21 and the pressure roller 22 grip the continuous sheet P from both sides in the thickness direction and rotate. The transport roller 21 rotates when the driving force of the transport motor 23 is transmitted. The pressure roller 22 is pressed against the transport roller 21 with a predetermined pressure and moves in conjunction with the rotation of the transport roller 21.

[0016] The image forming unit 30 is located downstream of the transport unit 20 in the transport direction of the continuous sheet P. The image forming unit 30 forms an image on the continuous sheet P by ejecting ink onto the continuous sheet P transported by the transport unit 20. The image forming unit 30 mainly comprises a recording head 31, a carriage motor 32, a platen 33, and a main scanning carriage 34.

[0017] The main scanning carriage 34 moves back and forth in the main scanning direction, which is perpendicular to the transport direction of the continuous sheet P, by the driving force transmitted from the carriage motor 32. The main scanning carriage 34 is also equipped with recording heads 31 that eject liquid inks of black (k), cyan (c), magenta (m), and yellow (y). More specifically, it is equipped with a recording head 31k that ejects black ink, a recording head 31c that ejects cyan ink, a recording head 31m that ejects magenta ink, and a recording head 31y that ejects yellow ink.

[0018] Each of the recording heads 31 ejects liquid ink of its respective color toward the continuous sheet P supported by the platen 33, according to instructions from the controller 50. Generally, the recording heads 31 eject liquid ink toward the direction of gravity. Therefore, the positional relationship between the main scanning carriage 34 and the platen 33 is vertical in the direction of gravity. That is, the platen 33 is located below the opposing main scanning carriage 34. The platen 33 then supports the continuous sheet P transported by the transport unit 20.

[0019] The winding unit 40 is located downstream of the conveying unit 20 and the image forming unit 30 in the conveying direction of the continuous sheet P. The winding unit 40 winds up the continuous sheet P on which the image has been formed by the image forming unit 30. The winding unit 40 mainly comprises a winding roller 41 and a winding motor 42. The winding roller 41 rotates in the direction of winding up the continuous sheet P after the image has been formed, by the driving force transmitted from the winding motor 42.

[0020] [Conventional setup methods and challenges] Here, we will explain the conventional method of setting roll paper with reference to Figure 22. The roll paper has flanges (flange members) at the 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 22(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 22(B) so that the leading edge of the paper is facing the user. Next, the user positions the leading edge of the paper between the guide plates at the back of the roll paper and inserts the roll paper while rotating it (Figure 22(C)). Once the user inserts the paper into the guides, the paper is fixed inside and pulled into the device.

[0021] As shown in Figure 22(C), the guide plate for inserting the leading edge of the paper is located behind the roll of paper, making it difficult to see and confirm whether the paper has been inserted correctly.

[0022] Furthermore, as shown in Figures 22(D) and 22(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.

[0023] In the conventional method of setting roll paper as described above, it was a time-consuming process because it was difficult to confirm insertion when finding the leading edge of the roll paper and inserting it in the transport direction, and it was necessary to insert the leading edge of the paper evenly. Furthermore, if the leading edge of the paper was not inserted evenly, it would be fed at an angle, causing skew, which would require repeating the operation or cause jams, adding even more hassle.

[0024] The sheet supply device according to the present invention solves the above-mentioned problems. It also solves the problem that arises when the direction in which the roll paper is set into the paper feeding receiving section (spool bearing base) of the device is reversed. The sheet supply section 10 as an embodiment of the sheet supply device according to the present invention will be described in detail below with reference to the drawings.

[0025] [Description of the sheet supply unit 10] Figure 3 is a schematic diagram of the sheet supply unit 10. Figure 4 is a perspective view of the guide arm 13 provided by the sheet supply unit 10. As shown in Figures 2, 3, and 4, the sheet supply unit 10 mainly comprises a support unit 11, a supply motor 12, a guide arm 13, a support shaft 14, a coil spring 15, a paper thickness sensor 16 as a first sensor, a plurality of rollers 17 (right roller 17a, left roller 17b), a cutter 18, and a guide plate 19 (upper guide plate 19a, lower guide plate 19b).

[0026] Furthermore, the sheet supply unit 10 includes a roll presser roller 70 positioned on the outer circumference of the roll 9 so as to contact the outer surface of the roll 9 in order to suppress slack in the continuous sheet P. The sheet supply unit 10 also includes a plurality of slack sensors 60, which act as second sensors, at predetermined positions on the outer circumference of the roll 9 to detect when slack occurs in a part of the continuous sheet P during the rotation of the roll 9, making normal rotation difficult. For example, the slack sensors 60 include a first slack sensor 61 at a position corresponding to the downstream side of the paper thickness sensor 16 in the rotation direction of the roll 9 during reverse rotation. It also includes a second slack sensor 62 at a position corresponding to the upstream side of the roller 17, and a third slack sensor 63 at a position corresponding to the upstream side of the roll presser roller 70.

[0027] The support section 11 supports a roll 9, which is formed by winding a continuous sheet P around a shaft-shaped spool 8. The support section 11 detachably supports the roll 9. The support section 11 also rotatably supports both ends of the spool 8.

[0028] The supply motor 12, acting as a rotating means, rotates the spool 8, supported by the support section 11, in a predetermined rotational direction. The rotation of the spool 8 by the supply motor 12 is distinguished into "forward rotation," which rotates the spool 8 in the direction of the feed direction R1 (forward direction) for unwinding the continuous sheet P, and "reverse rotation," which rotates the spool 8 in the direction of the winding direction R2 (reverse direction) for winding the continuous sheet P.

[0029] The guide arm 13, acting as a guide member, brings the paper thickness sensor 16 and rollers 17 (right roller 17a, left roller 17b) into contact with the roll 9, and also guides the continuous sheet P unwound from the roll 9 between the guide plates 19. The guide arm 13 has an elongated plate-like outer shape. The guide arm 13 has a facing portion 13a and a guide portion 13b.

[0030] The opposing portion 13a has an arc shape that follows the outer circumferential surface of the roll 9. The opposing portion 13a faces the outer circumferential surface of the roll 9 below the horizontal line passing through the rotation center of the spool 8. The guide portion 13b extends from the opposing portion 13a downstream in the direction of continuous sheet P supply. More specifically, the opposing portion 13a is positioned to face the region including the lower end of the roll 9 (lower region), and the guide portion 13b extends from the opposing portion 13a to a position between the guide plate 19.

[0031] The support shaft 14 extends in the same direction as the extension direction of the spool 8 supported by the support portion 11. The support shaft 14 is fixed inside each cover. The support shaft 14 is also attached to the downstream end of the guide portion 13b in the direction of continuous sheet P supply, and rotatably supports the guide arm 13. That is, the guide arm 13 is configured to rotate around the support shaft 14 as the pivot point, in a direction that brings the opposing portion 13a into contact with or away from the roll 9.

[0032] Furthermore, the coil spring 15, acting as a biasing member, biases the guide arm 13 in a direction that brings the opposing portion 13a closer to the roll 9.

[0033] The paper thickness sensor 16 protrudes from the opposing portion 13a toward the roll 9. Furthermore, the paper thickness sensor 16 is supported such that its protrusion from the opposing portion 13a changes as the relative position of the opposing portion 13a with respect to the opposing surface of the roll 9 changes. Additionally, the paper thickness sensor 16 is biased to contact the outer circumferential surface of the roll 9 (i.e., protrude from the opposing portion 13a). The paper thickness sensor 16 outputs a first detection signal to the controller 50, with a signal level corresponding to the amount of protrusion from the opposing portion 13a. More specifically, the greater the amount of protrusion of the paper thickness sensor 16 toward the roll 9 relative to the opposing portion 13a, the higher the signal level of the detection signal. Conversely, the smaller the amount of protrusion of the paper thickness sensor 16 relative to the opposing portion 13a (the greater the immersion into the opposing portion 13a), the lower the signal level of the detection signal.

[0034] Multiple rollers 17 are rotatably supported on the opposing section 13a. The rotation axis of each roller 17 extends in the same direction as the extension direction of the spool 8 and the support shaft 14. The rollers 17 are positioned differently from the paper thickness sensor 16 in the circumferential direction of the roll 9. For example, in the example of Figure 3, the rollers 17 are positioned upstream of the paper thickness sensor 16 in the winding direction R2. Furthermore, the rollers 17 are spaced apart in the width direction perpendicular to the circumferential direction of the roll 9, with the paper thickness sensor 16 positioned between the right roller 17a and the left roller 17b.

[0035] The first slack sensor 61, the second slack sensor 62, and the third slack sensor 63, like the paper thickness sensor 16, are normally in a state where they protrude in the direction toward contact with the roll 9. As the reversed roll 9 rotates in the winding direction R2, the leading edge of the sheet peels off, and the continuous sheet P may come into contact with or collide with a structure located on the outer circumference of the roll 9. At that time, the continuous sheet P becomes slack near the point of contact or collision. As the amount of slack in the continuous sheet P increases, the slack in the continuous sheet P pushes against the slack sensor 60, reducing its protrusion. The slack sensor 60 is configured such that the signal level of the second detection signal decreases when the protrusion decreases. Therefore, by monitoring the decrease in the signal level of the second detection signal of each slack sensor 60, it is possible to detect that slack is occurring in the continuous sheet P and to locate it.

[0036] Although not shown in Figure 3, the cutter 18 cuts the leading edge of the continuous sheet P across its entire width. The cutting line made by the cutter 18 extends in a direction perpendicular to the supply direction of the continuous sheet P. In other words, when the leading edge of the continuous sheet P is skewed relative to the supply direction, cutting the leading edge of the continuous sheet P with the cutter 18 makes the leading edge of the continuous sheet P perpendicular to the supply direction.

[0037] The guide plates 19 (upper guide plate 19a, lower guide plate 19b) are positioned downstream of the guide arm 13 in the direction of continuous sheet P supply. The upper guide plate 19a and the lower guide plate 19b are positioned opposite each other across the transport path L. The continuous sheet P, moving along the guide arm 13, passes between the upper guide plate 19a and the lower guide plate 19b and is supplied to the transport section 20. In other words, the guide plates 19 serve as a paper feed section into which the continuous sheet P unwound from the roll 9 enters.

[0038] [Operation when Roll 9 is set in the correct orientation] First, let's explain the case where roll 9 is set in the correct orientation. In the following explanation, setting roll 9 in the correct orientation will be referred to as "setting correctly." When set correctly, the leading edge of the continuous sheet P peeling off from roll 9 will be facing in the opposite direction to the winding direction R2.

[0039] This section describes the operation of the paper thickness sensor 16 and the changes in the detection signal when the spool 8 is rotated in the winding direction R2 after proper setting. Figures 5 to 7 are a series of diagrams illustrating the relationship between the position of the leading edge of the continuous sheet P (hereinafter referred to as the "sheet leading edge") and the signal level of the detection signal output by the paper thickness sensor 16. Figure 5 is an enlarged view of the area around the facing portion 13a. Figure 6 is a partially enlarged view showing the positional relationship between the sheet leading edge and the paper thickness sensor 16 and roller 17. Figure 7 is a diagram showing the change in the signal level of the detection signal from the paper thickness sensor 16 over time.

[0040] The guide arm 13 is biased toward the roll 9 by a coil spring 15 (see Figure 3) acting as a biasing member. Therefore, as shown in Figure 5, the paper thickness sensor 16 and the roller 17 are in contact with the outer circumferential surface of the roll 9. When the spool 8 is rotated in the winding direction R2, the leading edge of the sheet, which is in close contact with the outer circumferential surface of the roll 9, passes the roller 17, and then, due to further rotation in the winding direction R2, passes the paper thickness sensor 16. In the following description, as shown in Figure 5, the area before the leading edge of the sheet passes the roller 17 is referred to as "region α". The area after the leading edge of the sheet passes the roller 17 and before it passes the paper thickness sensor 16 is referred to as "region β". The area after the leading edge of the sheet passes the paper thickness sensor 16 is referred to as "region γ".

[0041] Figure 6(A) shows the state where the leading edge of the sheet is in region α. ​​Figure 6(B) shows the state where the leading edge of the sheet is in region β. First, as shown in Figures 6(A) and 6(B), when the leading edge of the sheet passes the roller 17, the guide arm 13 rotates by the thickness of the continuous sheet P in the direction in which the roller 17 contacts the outer surface of the roll 9. As a result, the paper thickness sensor 16 retracts into the opposite portion 13a by the thickness of the continuous sheet P. In other words, the amount of protrusion of the paper thickness sensor 16 decreases as the leading edge of the sheet passes the roller 17.

[0042] Figure 6(C) shows the state when the leading edge of the sheet reaches region γ. As shown in Figures 6(B) and 6(C), when the leading edge of the sheet passes the paper thickness sensor 16, the roller 17 comes into contact with the outer surface of the continuous sheet P, creating a gap equivalent to the thickness of the continuous sheet P. As a result, the paper thickness sensor 16 protrudes from the opposite portion 13a by an amount equivalent to the thickness of the continuous sheet P. In other words, the amount of protrusion of the paper thickness sensor 16 increases when the leading edge of the sheet passes the paper thickness sensor 16.

[0043] Figure 7(A) shows the change in the detection signal of the paper thickness sensor 16 when the roll 9 rotates in the winding direction R2 so that the leading edge of the sheet moves from Figure 6(A) to Figures 6(B) and 6(C). That is, as shown in Figure 7(A), the detection signal of the paper thickness sensor 16 is a High signal before the leading edge of the sheet passes the roller 17 (region α in Figure 5), and a Low signal after the leading edge of the sheet passes the roller 17 (region β in Figure 5). Note that the High signal has a higher signal level than the Low signal. In other words, the detection signal of the paper thickness sensor 16 decreases in signal level when the leading edge of the sheet passes the roller 17 (right roller 17a, left roller 17b).

[0044] Furthermore, after the leading edge of the sheet passes the paper thickness sensor 16 (region γ in Figure 5), the detection signal of the paper thickness sensor 16 changes from a LOW signal to a High signal. In other words, the detection signal of the paper thickness sensor 16 increases in level as the leading edge of the sheet passes the paper thickness sensor 16.

[0045] Here, as shown in Figure 7(B), when we microscopically observe the change in the signal level of the detection signal, we see that as the leading edge of the sheet passes through roller 17, the detection signal of the paper thickness sensor 16 decreases by signal level y1 during time x1. Also, as the leading edge of the sheet passes through paper thickness sensor 16, the detection signal of paper thickness sensor 16 increases by signal level y2 during time x2.

[0046] Hereinafter, the rate of change per unit time of the signal level of the detection signal will be referred to as the "rate of change of signal". The rate of change of signal when the paper thickness sensor 16 is submerged will be referred to as the first rate of change, and the rate of change of signal when the paper thickness sensor 16 is protruding will be referred to as the second rate of change. Furthermore, as will be described in detail later, the rate of change per unit time of the signal level of the detection signal generated when the roll 9 is rotated in the winding direction R2 with the roll 9 incorrectly set will be referred to as the reverse set rate of change.

[0047] Furthermore, the first signal change rate K1 = |y1 / x1| when the leading edge of the sheet passes the roller 17 exceeds a predetermined first threshold when the roll 9 is rotated in the winding direction R2, provided that the roll 9 is properly set. Also, the second signal change rate K2 = |y2 / x2| when the leading edge of the sheet passes the paper thickness sensor 16 exceeds a predetermined second threshold when the roll 9 is rotated in the winding direction R2, provided that the roll 9 is properly set. The first and second thresholds are thresholds to absorb minute variations in the diameter of the roll 9. The first and second thresholds may be the same value or different values.

[0048] As described above, in the sheet supply unit 10, if the roll 9 is correctly set, when the roll 9 is rotated in the winding direction R2 (reverse rotation), the detection signal of the paper thickness sensor 16 changes from a HIGH signal to a LOW signal and then back to a HIGH signal. This change in the detection signal occurs within a time range corresponding to the rotation speed of the reverse rotation. Based on these, it is possible to determine whether the roll 9 is set in the correct orientation and to determine the position of the leading edge of the sheet.

[0049] [Operation when Roll 9 is set in reverse] Next, we will explain the relationship between the position of the leading edge of the sheet and the signal level of the detection signal output by the paper thickness sensor 16 when the roll 9 is set in reverse relative to the sheet supply unit 10. Figure 8 is an enlarged view similar to Figure 5, illustrating the state in which the roll 9 is set in reverse. Figure 9 is a diagram showing the positional relationship between the leading edge of the continuous sheet P and the paper thickness sensor 16 and roller 17 when the roll 9 is set in reverse. Figure 10 is a diagram showing the change in the signal level of the detection signal of the paper thickness sensor 16 over time when set in reverse.

[0050] As shown in Figure 8, when the roll 9 is set in reverse, the leading edge of the continuous sheet P is facing in the opposite direction to when it is set in the correct direction, i.e., in the winding direction R2. Starting from the state where the leading edge of the sheet is in region α as shown in Figure 9(A), the sheet rotates in the winding direction R2 and the leading edge of the sheet passes the roller 17. When the leading edge of the sheet passes the roller 17, the position of the roller 17 relative to the outer surface of the roll 9 is displaced by the thickness of the continuous sheet P in a direction away from the outer surface of the roll 9 (Figure 9(B)). As a result, the guide arm 13 rotates by the thickness of the continuous sheet P, and the paper thickness sensor 16 protrudes from the opposite portion 13a by the thickness of the continuous sheet P. In other words, the amount of protrusion of the paper thickness sensor 16 increases as the leading edge of the sheet passes the roller 17.

[0051] Up to Figure 9(B), the paper thickness sensor 16 is in contact with the outer surface of the roll 9. As the roll 9 rotates in this state, the paper thickness sensor 16 outputs a detection signal corresponding to the minute displacement of the outer surface.

[0052] Next, when the leading edge of the sheet reaches region γ (Figure 9(C)), the leading edge of the sheet passes through the paper thickness sensor 16, causing the paper thickness sensor 16 to retract into the opposite portion 13a by an amount equivalent to the thickness of the continuous sheet P. In other words, the amount of protrusion of the paper thickness sensor 16 decreases as the leading edge of the sheet passes through the paper thickness sensor 16.

[0053] Therefore, when the roll 9 is rotated in the winding direction R2 with the roll 9 set in reverse, the detection signal of the paper thickness sensor 16 does not change as it would in the correct set state, but changes in the opposite direction as shown in Figure 10. That is, the detection signal of the paper thickness sensor 16 changes from a LOW signal to a HIGH signal and then back to a LOW signal, and this change occurs in accordance with the rotation speed in the winding direction R2. By monitoring the direction of change in the detection signal of the paper thickness sensor 16, it is possible to detect that the roll 9 is set in reverse.

[0054] [Explanation of problems that occur when the parts are set up in reverse] While it is possible to detect a reversed setting based on the change in the detection signal of the paper thickness sensor 16 when the roll 9 is rotated in the winding direction R2 with the roll 9 set in the reverse position, the leading edge of the sheet may peel off from the outer surface of the roll 9 and become loose when the reverse rotation is stopped upon detection of the reverse setting. Examples of problems that may occur when the roll is set in the reverse position are described below.

[0055] [First example of a problem caused by reverse setting] When roll 9 is set in reverse and rotated in the winding direction R2, if the leading edge of the sheet remains wrapped around the outer circumference of roll 9 without detaching, the sheet leading edge will not be detected, causing the reverse rotation to continue and damaging roll 9.

[0056] Furthermore, as illustrated in Figure 11, if the leading edge of the continuous sheet P that has peeled off from the roll 9 hits the roller 17 and cannot pass, the reverse rotation continues, causing the continuous sheet P to accumulate upstream of the roller 17 and become slack. In this case, the second slack sensor 62 is pressed by the slackened continuous sheet P, so the detection signal of the second slack sensor 62 becomes a LOW signal.

[0057] When the detection signal from the second slack sensor 62 becomes a LOW signal, it can be detected that the roll 9 is in the reversed set state and that the continuous sheet P is slack at the upstream position of the roller 17, as illustrated in Figure 11.

[0058] [Second example of a problem caused by reverse setting] When the roll 9 is reversed and rotated in the reverse direction (winding direction R2), if the leading edge of the continuous sheet P that has detached from the roll 9 hits the roll retainer roller 70 and cannot pass, the continuous sheet P accumulates upstream of the roll retainer roller 70 and becomes slack as the reverse rotation continues. In this case, the third slack sensor 63 is pressed by the slackened continuous sheet P, so the detection signal of the second slack sensor 62 becomes a LOW signal.

[0059] Therefore, when the detection signal from the third slack sensor 63 becomes a LOW signal, it can be detected that the roll 9 is in the reversed set state and that the continuous sheet P is slack at the upstream position of the roller 17, as illustrated in Figure 12.

[0060] [Third example of a problem caused by reverse setting] When roll 9 is reversed and rotated in the reverse direction (winding direction R2), even if the leading edge of the continuous sheet P that has peeled off from roll 9 passes the roll retaining roller 70 or roller 17, if the reverse rotation continues, the leading edge of the sheet will be pushed out from the end of the guide arm 13. In this case, the first slack sensor 61, which is installed near the end of the guide arm 13, is pressed by the slackened continuous sheet P, so the detection signal of the first slack sensor 61 becomes a LOW signal.

[0061] Therefore, when the detection signal from the first slack sensor 61 becomes a LOW signal, it can be detected that the roll 9 is in the reversed set state and that the continuous sheet P is being discharged from the guide arm 13, as illustrated in Figure 13.

[0062] [Control block that performs the reverse set detection process for roll 9] Below, we will explain the process for detecting the reverse setting of roll 9 in order to address the examples of malfunctions described above. First, we will explain the control block that enables the reverse setting detection process using Figure 14. Figure 14 shows the hardware configuration of printer 1 that executes the control process described above.

[0063] As shown in Figure 14, the printer 1 has a configuration in which a CPU (Central Processing Unit) 51 as a control means, RAM (Random Access Memory) 52 as a storage means, ROM (Read Only Memory) 53 as a storage means, HDD (Hard Disk Drive) 54 as a storage means, and an I / F 55 as an interface are connected via a common bus 56 as a communication means. The CPU 51, RAM 52, ROM 53, and HDD 54 are examples of the controller 50.

[0064] The CPU 51 is the processing unit and controls the overall operation of the printer 1. The RAM 52 is a volatile storage medium that allows for high-speed reading and writing of information and is used as a workspace for the CPU 51 when processing information. The ROM 53 is a read-only, non-volatile storage medium that stores programs such as firmware. The HDD 54 is a non-volatile storage medium that allows for reading and writing of information and has a large storage capacity, and stores the OS (Operating System), various control programs, application programs, etc.

[0065] Printer 1 processes various programs loaded from ROM 53 and HDD 54 into RAM 52 using the arithmetic functions of the CPU 51. This processing constitutes a software control unit that includes various functional modules of Printer 1. The combination of this software control unit and the hardware resources installed in Printer 1 constitutes a functional block that realizes the functions of Printer 1.

[0066] I / F55 is an interface that connects the sheet supply unit 10, transport unit 20, image forming unit 30, winding unit 40, and operation panel (input unit) 57 to the common bus 56. In other words, the controller 50 controls the sheet supply unit 10, transport unit 20, image forming unit 30, winding unit 40, operation panel 57, and alarm 58 through I / F55.

[0067] The control panel 57 is a user interface equipped with a display that shows various information to be communicated to the operator, and buttons, switches, dials, etc., that accept operations from the operator. The control panel 57 may also be equipped with a touch panel superimposed on the display. It accepts operations from the operator and outputs an operation signal corresponding to the accepted operation to the controller 50.

[0068] The alarm 58, as a notification device, emits a notification sound when it notifies the operator that a reverse setting has been detected or that slack has been detected. The control panel 57 displays various information to be notified, and the alarm 58 should emit a sound corresponding to the content of the information to be notified.

[0069] [First embodiment of reverse set detection processing] Next, the first embodiment of the sheet setting process will be described using the flowchart in Figure 15. This is an example of the control processing flow described below and the processing implemented in the controller 50 mentioned above.

[0070] When the sheet setting process begins, the supply motor 12 starts rotating in the reverse direction to rotate the roll 9 in the winding direction R2 (S1501). After the reverse rotation starts, the changes in the detection signals of the paper thickness sensor 16 and each slack sensor 60 are monitored. If the detection signal of the paper thickness sensor 16 does not determine that the roll is in a reverse set state (S1502: NO), and the detection signal of the first slack sensor 61 also does not determine that the roll is in a reverse set state (S1503: NO), the set state of the roll 9 may be correct, so the sheet leading edge detection is determined (S1504).

[0071] In S1504, if the leading edge of the sheet is not detected (S1504:NO), the process returns to S1502 and the above determination process is repeatedly executed.

[0072] In S1504, if the leading edge of the sheet is detected (S1504: Yes), the process ends and the process moves to the next stage. The next stage of processing is, for example, the process of unwinding the leading edge of the sheet in the transport direction and starting the transport of the continuous sheet P. Details of the sheet leading edge detection process are omitted.

[0073] If, in S1502, the detection signal of the paper thickness sensor 16 changes to one that indicates reverse setting (S1502: Yes), or if, in S1503, the detection signal of the first slack sensor 61 is a LOW signal (S1503: Yes), then the roll 9 is set in reverse. In this case, the rotation of the roll 9 is stopped (S1505), information such as "The paper is set in reverse, please set it in the correct orientation" is displayed on the operation panel 57, and at the same time, an alarm 58 is emitted to indicate that the paper is set in reverse (S1506), and the process is terminated.

[0074] As described above, if the leading edge of the continuous sheet P detaches from the guide arm 13 and is discharged from the sheet supply unit 10, the detection signal from the first slack sensor 61 is monitored to detect the reverse setting. This stops the reverse rotation of the roll 9 and prevents damage to the continuous sheet P.

[0075] [Second embodiment of reverse set detection processing] Next, a second embodiment of the sheet setting process will be described using the flowchart in Figure 16. This is an example of the control processing flow described below and the processing implemented in the controller 50 mentioned above.

[0076] When the sheet setting process begins, the supply motor 12 starts rotating in the reverse direction to rotate the roll 9 in the winding direction R2 (S1601). After the reverse rotation starts, the changes in the detection signals of the paper thickness sensor 16 and each slack sensor 60 are monitored. If the detection signal of the paper thickness sensor 16 does not determine that the roll is in a reverse set state (S1602: NO), the detection signal of the first slack sensor 61 does not determine that the roll is in a reverse set state (S1603: NO), and the detection signal of the second slack sensor 62 does not determine that the roll is in a reverse set state (S1604: NO), then the set state of the roll 9 may be correct, and a determination is made to detect the sheet leading edge (S1604).

[0077] In S1604, if the leading edge of the sheet is not detected (S1604:NO), the process returns to S1602 and the above determination process is repeatedly executed.

[0078] In S1604, if the leading edge of the sheet is detected (S1604:Yes), the process ends and the process moves to the next stage. The next stage of processing is, for example, the process of unwinding the leading edge of the sheet in the transport direction and starting the transport of the continuous sheet P. Details of the sheet leading edge detection process are omitted.

[0079] If, in S1602, the detection signal of the paper thickness sensor 16 changes to one that indicates reverse setting (S1602: Yes), if, in S1603, the detection signal of the first slack sensor 61 is a LOW signal (S1603: Yes), or if, in S1604, the detection signal of the second slack sensor 62 is a LOW signal (S1604: Yes), then the roll 9 is set in reverse. In this case, the rotation of the roll 9 is stopped (S1606), information such as "The paper is set upside down, please set it in the correct orientation" is displayed on the operation panel 57, and at the same time, an alarm 58 is emitted to indicate that the paper is set upside down (S1607), and the process is terminated.

[0080] As described above, the second slack sensor 62, located downstream of the roller 17 in the rotational direction, detects when the continuous sheet P slackens due to collision with the roller 17. This allows for earlier detection of abnormal conditions than the reverse set detection by the first slack sensor 61, thus more reliably preventing damage to the continuous sheet P.

[0081] [Third Embodiment], Next, a third embodiment of the sheet setting process will be described using the flowchart in Figure 17. This is an example of the control processing flow described below and the processing implemented in the controller 50 mentioned above.

[0082] When the sheet setting process begins, the supply motor 12 starts rotating in the reverse direction to rotate the roll 9 in the winding direction R2 (S1701). After the reverse rotation starts, the changes in the detection signals of the paper thickness sensor 16 and each slack sensor 60 are monitored. If the detection signal of the paper thickness sensor 16 does not determine that the roll is in a reverse set state (S1702: NO), the detection signal of the first slack sensor 61 does not determine that the roll is in a reverse set state (S1703: NO), the detection signal of the second slack sensor 62 does not determine that the roll is in a reverse set state (S1704: NO), and the detection signal of the third slack sensor 63 does not determine that the roll is in a reverse set state (S1705: NO), then the set state of the roll 9 may be correct, and a determination is made to detect the sheet leading edge (S1706).

[0083] In S1706, if the leading edge of the sheet is not detected (S1706:NO), the process returns to S1602 and the above determination process is repeatedly executed.

[0084] In S1706, if the leading edge of the sheet is detected (S1706: Yes), the process ends and the process moves to the next stage. The next stage of processing is, for example, the process of unwinding the leading edge of the sheet in the transport direction and starting the transport of the continuous sheet P. Details of the sheet leading edge detection process are omitted.

[0085] If, in S1702, the detection signal of the paper thickness sensor 16 changes to one that indicates reverse setting (S1702:Yes), or in S1703, the detection signal of the first slack sensor 61 is a LOW signal (S1703:Yes), or in S1704, the detection signal of the second slack sensor 62 is a LOW signal (S1704:Yes), or in S1705, the detection signal of the third slack sensor 63 is a LOW signal (S1705:Yes), then the roll 9 is set in reverse. In this case, the rotation of the roll 9 is stopped (S1707), information such as "The paper is set upside down, please set it in the correct orientation" is displayed on the operation panel 57, and at the same time, an alarm 58 is emitted to indicate that the paper is set upside down (S1708), and the process is terminated.

[0086] As described above, the third slack sensor 63, which is located downstream of the roller 17 in the rotational direction and downstream of the roll-holding roller 70 in the rotational direction, detects when the continuous sheet P slackens due to collision with the roll-holding roller 70. This allows for early detection of reverse setting and abnormal conditions at locations where slack is likely to occur during reverse setting, thereby more efficiently suppressing the occurrence of slack in the continuous sheet P.

[0087] [Fourth Embodiment] Next, the fourth embodiment of the sheet setting process will be described using the flowchart in Figure 18. This is an example of the control processing flow described below and the processing implemented in the controller 50 mentioned above.

[0088] When the sheet setting process begins, the supply motor 12 starts rotating in the reverse direction to rotate the roll 9 in the winding direction R2, and the measurement of the reverse rotation speed Nr begins (S1801). After the reverse rotation starts, the changes in the detection signals of the paper thickness sensor 16 and each slack sensor 60 are monitored. If the detection signal of the paper thickness sensor 16 does not determine that the roll is in a reverse set state (S1802: NO), and the detection signal of the first slack sensor 61 also does not determine that the roll is in a reverse set state (S1803: NO), and the reverse rotation speed Nr has not reached a predetermined threshold, the rotation threshold Ne (S1804: NO), then the set state of the roll 9 may be correct, and the determination of sheet tip detection is made (S1805).

[0089] In S1804, if the leading edge of the sheet is not detected (S1805: NO), the process returns to S1602 and the above determination process is repeated. At this time, one rotation is added to the reverse rotation speed Nr.

[0090] In S1805, if the leading edge of the sheet is detected (S1805:Yes), the process ends and the process moves to the next stage. The next stage of processing is, for example, the process of unwinding the leading edge of the sheet in the transport direction and starting the transport of the continuous sheet P. Details of the sheet leading edge detection process are omitted.

[0091] In S1802, if the detection signal of the paper thickness sensor 16 changes to one that indicates reverse setting (S1802: Yes), or in S1803, if the detection signal of the first slack sensor 61 is a LOW signal (S1803: Yes), or in S1804, if the reverse rotation speed Nr reaches the rotation threshold Ne (S1804: Yes), it is determined that the roll 9 is set in reverse. Therefore, the rotation of the roll 9 is stopped (S1806), information such as "The paper is set in reverse, please set it in the correct orientation" is displayed on the operation panel 57, and an alarm 58 is emitted to indicate that the paper is set in reverse (S1807), and the process is terminated.

[0092] According to this embodiment, when the roll 9 is set with the leading edge of the continuous sheet P sealed with a sealing material to prevent the winding state from collapsing, and when the leading edge of the sheet is not peeled off, it is possible to handle cases where the leading edge cannot be detected by reverse rotation. In other words, when executing the process to detect the leading edge of the sheet, an acceptable number of reverse rotations is predetermined as the rotation threshold Ne, and the upper limit of the reverse rotation is controlled in the sheet setting process. As a result, even if the sheet is set correctly, if it is difficult to detect the leading edge of the sheet, the reverse rotation of the roll 9 can be stopped and the user can be notified of the setting abnormality.

[0093] [Fifth Embodiment] Next, the fifth embodiment of the sheet setting process will be described using the flowchart in Figure 19. This is an example of the control processing flow described below and the processing implemented in the controller 50 mentioned above.

[0094] When the sheet setting process begins, the supply motor 12 starts rotating in the reverse direction to rotate the roll 9 in the winding direction R2, and the measurement of the reverse rotation speed Nr begins (S1901). After the reverse rotation starts, the changes in the detection signals of the paper thickness sensor 16 and each slack sensor 60 are monitored. If the detection signal of the paper thickness sensor 16 does not determine that the roll is in a reverse set state (S1902: NO), or if the detection signal of the first slack sensor 61 does not determine that the roll is in a reverse set state (S1903: NO), then the set state of the roll 9 is likely correct, and a determination is made as to whether the sheet leading edge has been detected (S1904).

[0095] In S1904, if the leading edge of the sheet is not detected (S1904:NO), the process returns to S1902 and the above determination process is repeated. At this time, one rotation is added to the reverse rotation speed Nr.

[0096] In S1904, if the leading edge of the sheet is detected (S1904:Yes), the process ends and the process moves to the next stage. The next stage of processing is, for example, the process of unwinding the leading edge of the sheet in the transport direction and starting the transport of the continuous sheet P.

[0097] In S1902, if the change in the detection signal of the paper thickness sensor 16 is that of the reverse setting (S1902: Yes), or in S1903, if the detection signal of the first slack sensor 61 is a LOW signal (S1903: Yes), the rotation of the roll 9 is stopped, and the measurement of the reverse rotation speed Nr is also stopped (S1905).

[0098] Next, the forward rotation of roll 9 is started, and the measurement of the forward rotation speed Nf is also started (S1906). The forward rotation continues until the forward rotation speed Nf reaches the reverse rotation speed Nr (S1906: No). When the forward rotation speed Nf reaches the reverse rotation speed Nr (S1906: Yes), the forward rotation of roll 9 is stopped (S1908).

[0099] In this case, since roll 9 was set upside down, the control panel 57 displays information such as "The paper is set upside down, please set it in the correct orientation," and also provides an audible alert (S1909), and then terminates the process.

[0100] According to this embodiment, if the leading edge of the sheet deviates from the transport path and extends outside the guide arm 13, the detection signal from the first slack sensor 61 detects this abnormal condition and stops the reverse rotation of the roll 9. Until it stops, the continuous sheet P is fed out to the outside of the guide arm 13 by a length equivalent to the reverse rotation speed Nr. Then, by performing forward rotation for a length equivalent to the reverse rotation speed Nr until the reverse set is detected and the reverse rotation is stopped, the discharged continuous sheet P can be rewound onto the spool 8. This prevents soiling and damage to the continuous sheet P.

[0101] [Sixth Embodiment] Next, the sixth embodiment of the sheet setting process will be described using the flowcharts in Figures 20 and 21. These are examples of the control processing flow described below and the processing implemented in the controller 50 mentioned above.

[0102] When the sheet setting process begins, the supply motor 12 starts rotating in the reverse direction to rotate the roll 9 in the winding direction R2, and the measurement of the reverse rotation speed Nr begins (S2001). After the reverse rotation starts, the changes in the detection signals of the paper thickness sensor 16 and each slack sensor 60 are monitored. If the detection signal of the paper thickness sensor 16 does not determine that the roll is in a reverse set state (S2002: NO), or the detection signal of the first slack sensor 61 does not determine that the roll is in a reverse set state (S2003: NO), or the detection signal of the second slack sensor 62 does not determine that the roll is in a reverse set state (S2004: NO), or the detection signal of the third slack sensor 63 does not determine that the roll is in a reverse set state (S2005: NO), then the set state of the roll 9 is likely correct, and the sheet leading edge detection is determined (S2006).

[0103] In S2006, if the leading edge of the sheet is not detected (S2006:NO), the process returns to S2002, and the above determination process is repeated. At this time, one rotation is added to the reverse rotation number Nr.

[0104] In S2006, if the leading edge of the sheet is detected (S2006:Yes), the process ends and the process moves to the next stage. The next stage of processing is, for example, the process of unwinding the leading edge of the sheet in the transport direction and starting the transport of the continuous sheet P. Details of the sheet leading edge detection process are omitted.

[0105] In S2002, if the detection signal of the paper thickness sensor 16 changes to one that indicates the paper has been set in the wrong direction (S1902: Yes), the reverse rotation of the roll 9 is stopped (S2007). In this case, the roll 9 has been set in the wrong direction, so information such as "The paper is set in the wrong direction, please set it in the correct direction" is displayed on the control panel 57, and an alarm 58 is emitted to indicate that the paper has been set in the wrong direction (S2008), and the process is terminated.

[0106] If the detection signal from the first slack sensor 61 is LOW in S2003 (S2003:Yes), if the detection signal from the second slack sensor 62 is LOW in S2004 (S2004:Yes), or if the detection signal from the third slack sensor 63 is LOW in S2005 (S2005:Yes), the process shown in Figure 21 is performed.

[0107] As shown in Figure 21, if any of the detection signals from the slack sensors 60 are LOW in the preceding processing, it means that the roll 9 is in a reversed state, so first the reverse rotation of the roll 9 is stopped, and at the same time the measurement of the reverse rotation speed Nr is also stopped (S2101).

[0108] Next, the forward rotation of roll 9 is started, and the measurement of the forward rotation speed Nf is also started (S2202). As long as the forward rotation speed Nf has not reached the reverse rotation speed Nr, the detection signal of the first slack sensor 61 remains in the reverse set state (S2104: Yes), the detection signal of the second slack sensor 62 remains in the reverse set state (S2105: Yes), and the detection signal of the third slack sensor 63 remains in the reverse set state (S2106: Yes), the forward rotation is continued.

[0109] When the forward rotation speed Nf reaches the reverse rotation speed Nr (S2103: Yes), or when the detection signal from either of the slack sensors 60 is no longer a LOW signal (S2104: No, S2105: No, S2106: No), the forward rotation of the roll 9 is stopped (S21087).

[0110] In this case, since roll 9 was set upside down, the control panel 57 displays information such as "The paper is set upside down, please set it in the correct orientation," and simultaneously emits an alarm sound via alarm 58 to indicate that it was set up upside down (S2109), and then the process is terminated.

[0111] According to this embodiment, if the leading edge of the sheet deviates from the transport path and extends outside the guide arm 13, the detection signal from the first slack sensor 61 detects this abnormal condition and stops the reverse rotation of the roll 9. Until it stops, the continuous sheet P will either be fed out to the outside of the guide arm 13 by a length equivalent to the reverse rotation speed Nr, or it will slacken at one of these positions. Therefore, by performing forward rotation for an amount equivalent to the reverse rotation speed Nr until the reverse set is detected and the reverse rotation is stopped, the discharged continuous sheet P and the slack can be eliminated and the spool 8 can be rewound. This prevents soiling and damage to the continuous sheet P.

[0112] In the embodiments described above, the forward rotation speed Nf is defined based on the previous rotation speed (reverse rotation speed Nr) when performing the rewind operation, but the control is not limited to this. For example, the control may be based on the rotation time of the roll 9 during the roll setting process.

[0113] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the technical essence, and all technical matters included in the technical concept described in the claims are subject to the present invention. The above embodiments are shown as preferred examples, but those skilled in the art can realize various modifications from the disclosed content. Such modifications are also included in the technical scope described in the claims. [Explanation of symbols]

[0114] 1: Printer 8: Spool 9: Roll 10: Sheet supply unit 12: Supply motor 13: Guide Arm 13a: Face-to-face section 16: Paper thickness sensor 17: Koro 30: Image forming unit 50: Controller 51: CPU 52: RAM 53: ROM 54: HDD 55: I / F 56: Common Bus 57: Control Panel 58: Alarm 60: Slack Sensor 61: First slack sensor 62: Second slack sensor 63: Third slack sensor 70: Roller presser roller [Prior art documents] [Patent Documents]

[0115] [Patent Document 1] Japanese Patent Publication No. 2018-150107

Claims

1. A support section that supports a roll formed by winding a long sheet onto a spool, A rotating means for rotating the sheet in the forward direction, which unwinds the sheet from the roll supported by the support portion, and in the reverse direction, which winds the sheet onto the roll. A guide member having a facing portion that faces the outer circumferential surface of the roll, and a guide portion that extends from the facing portion toward the forward direction of the sheet, The end portion of the guide member, with the downstream end in the forward direction as the pivot point, supports the guide member so that it can rotate in a direction that moves the opposing portion closer to or further away from the outer circumferential surface, A biasing member that biases the rotation of the guide member in a direction that brings the opposing portion closer to the roll, A first sensor is provided, which protrudes from the opposing portion toward the roll and is biased in a direction to contact the outer circumferential surface of the roll, and outputs a first detection signal with a signal level corresponding to the amount of protrusion. A roller supported by the aforementioned opposing portion and in contact with the outer circumferential surface of the roll at a position different from the first sensor in the circumferential direction of the roll, The system includes a controller that controls the rotating means based on the signal change rate, which is the amount of change per unit time in the signal level of the first detection signal, The aforementioned controller, A sheet supply device characterized by rotating the spool in the opposite direction using the rotating means, determining whether the spool is set in the correct orientation or in the wrong orientation in the support portion based on the first detection signal when the leading edge of the sheet passes the first sensor, and stopping the operation of the rotating means when the spool is set in the wrong orientation.

2. The system includes a second sensor that protrudes toward the outer surface of the roll and outputs a second detection signal in accordance with the slack of the sheet that has peeled off from the roll, The aforementioned controller, The sheet supply device according to claim 1, wherein when the spool is rotated in the opposite direction by the rotating means, the device determines whether or not there is slack in the sheet based on the second detection signal, and stops the operation of the rotating means when slack has occurred in the sheet.

3. The sheet supply device according to claim 2, wherein the controller measures the number of reverse rotations until the operation of the rotating means is stopped, and stops the rotating means when the number of reverse rotations exceeds a predetermined threshold.

4. The sheet supply device according to claim 3, wherein at least one second sensor is installed upstream of the roller when it is rotating in the reverse direction.

5. The sheet supply device according to claim 3, wherein at least two of the second sensors are installed upstream of the roller when it is rotating in the reverse direction.

6. The sheet supply device according to claim 4 or 5, wherein the second sensor is installed at least downstream of the first sensor during reverse rotation and near the end of the guide member.

7. The sheet supply device according to claim 6, wherein when the controller stops the operation of the rotating means due to slack in the sheet, the rotating means rotates the spool forward based on the reverse rotation speed and then stops the rotating means.

8. The sheet supply device according to claim 6 or 7, wherein when the controller stops the operation of the rotating means due to slack in the sheet, the controller rotates the spool forward using the rotating means based on the reverse rotation speed, and stops the rotating means based on the detection signal of the second sensor.

9. The system includes a notification means for notifying the details of the control of the rotation of the spool, The sheet supply device according to any one of claims 1 to 7, wherein the controller determines that the spool is set in the support portion in the reverse direction, and when the spool is set in the reverse direction, it issues a warning via the notification means.

10. A sheet supply device according to any one of claims 1 to 9, An image forming apparatus comprising an image forming unit that forms an image on a sheet supplied by the sheet supply device.

Images