JP7580960B2 - Sheet Feeding Device - Google Patents

Description

The present invention relates to a sheet supplying device that supplies sheets.

A known sheet feeder that supplies sheets is one that blows air onto sheets stacked on a sheet feed tray to lift the sheets, and then uses a suction and conveyance means to suction and convey the topmost sheet of the lifted sheets to feed them to a destination.

In such a paper feed device, the paper feed tray is raised in response to a decrease in the amount of paper remaining on the tray, and is controlled to maintain the height position of the top surface of the topmost sheet of paper stacked on the tray.

JP 2010-120721 A

In the above-mentioned paper feed device, when the amount of paper remaining on the paper feed tray becomes low, the amount of air blown onto each sheet of paper increases, causing the behavior of the paper to become disrupted.

This can lead to problems with paper feeding. For example, multiple sheets of paper may be adsorbed to the adsorption conveying means, resulting in double feeding, or the paper may climb over an end fence that regulates the upstream end of the paper in the conveying direction, resulting in empty feeding.

The present invention has been made in consideration of the above, and aims to provide a sheet feeding device that can reduce sheet feeding problems.

To achieve the above object, the sheet supplying device of the present invention comprises a liftable loading platform on which sheets are loaded, a floating section which blows air onto the sheets loaded on the loading platform to lift the sheets, a transport section which transports the topmost sheet among the sheets lifted by the floating section, and a control section which controls the lifting of the loading platform in response to a decrease in the remaining amount of sheets on the loading platform, and is characterized in that the control section performs last mode control which fixes the loading platform at a predetermined height position when the remaining amount of sheets on the loading platform is within a specified remaining amount range, and controls the wind speed of the floating section in response to the specified remaining amount range and the height position.

The sheet supply device of the present invention can reduce sheet supply problems.

1 is a schematic configuration diagram of a paper feed device according to a first embodiment. 2 is a control block diagram of the paper feeder shown in FIG. 1 . FIG. 2 is a partially enlarged plan view of the paper feeder shown in FIG. 1 . 2 is an enlarged view of the vicinity of a main floating air outlet of the paper feeder shown in FIG. 1 . 2 is a partial enlarged view of a side fence of the paper feeder shown in FIG. 1 . FIG. 13 is a diagram showing a last mode table. FIG. 13 is a diagram showing a floating state of a paper sheet. 13 is a flowchart of paper feed control in the final stage of paper feeding. 11A and 11B are diagrams illustrating an example of changes in the height position of the paper feed tray and the remaining amount of paper in the last follow-up mode control and the last mode control. 13A and 13B are diagrams illustrating an example of a transition in the height position of the paper feed tray and the remaining amount of paper when transitioning from normal mode control to last mode control without performing last follow-up mode control; 10 is a flowchart illustrating an operation of a paper feed device according to a second embodiment. 10 is a flowchart illustrating an operation of a paper feed device according to a second embodiment. 11 is an explanatory diagram of a method for detecting the number of sheets stacked on a sheet feed tray. FIG. 13 is an explanatory diagram of the height position of the paper feed tray in a paper feed operation under low remaining amount mode control. FIG.

The following describes an embodiment of the present invention with reference to the drawings. The same or equivalent parts and components are designated by the same or equivalent reference numerals throughout the drawings.

The embodiments shown below are examples of devices that embody the technical idea of this invention, and the technical idea of this invention does not specify the materials, shapes, structures, arrangements, etc. of each component part to those described below. The technical idea of this invention can be modified in various ways within the scope of the claims.

[First embodiment]
FIG. 1 is a schematic diagram of a sheet feeding device according to a first embodiment of the present invention. FIG. 2 is a control block diagram of the sheet feeding device shown in FIG. 1. FIG. 3 is a partially enlarged plan view of the sheet feeding device shown in FIG. 1. FIG. 4 is an enlarged view of the vicinity of the main floating air outlet of the sheet feeding device shown in FIG. 1. FIG. 5 is a partially enlarged view of a side fence of the sheet feeding device shown in FIG. 1. In the following description, the direction perpendicular to the paper surface of FIG. 1 is defined as the front-rear direction, and the front direction of the paper surface is defined as the forward direction. Furthermore, the top, bottom, left, and right directions of the paper surface in FIG. 1 are defined as the top, bottom, left, and right directions.

As shown in Figures 1 to 3, the paper feeder (corresponding to a sheet supplying device) 1 of this embodiment includes a paper feed tray (corresponding to a loading tray) 2, a lifting motor 3, a motor encoder 4, a paper presence sensor 5, a paper feed tray sensor 6, a paper feed guide plate 7, a separation gate 8, two side fences 9, an end fence 10, a floating section 11, a separation section 12, a transport section 13, an upper limit sensor 14, and a control section 15.

The paper feeder 1 is a device that feeds paper (corresponding to a sheet) P to a printing unit (not shown) of a printing device. The direction from left to right in FIG. 1 is the direction in which paper P is transported by the transport unit 13 during paper feeding operation. In the following description, upstream and downstream refer to upstream and downstream in the direction in which paper P is transported by the transport unit 13.

The paper feed tray 2 is where the paper P used for printing is loaded. The paper feed tray 2 is configured to be able to rise and fall.

The paper feed tray 2 has a fence insertion hole 2a through which a side fence 9 to which a side lifting mechanism 22 and a side separation mechanism 42 (described later) are attached is inserted. Two fence insertion holes 2a are formed corresponding to the two side fences 9, respectively. One fence insertion hole 2a is formed in the front end of the paper feed tray 2, and the other fence insertion hole 2a is formed in the rear end of the paper feed tray 2.

In addition, the paper feed tray 2 is provided with a detection plate 2b, which is the object to be detected by the paper feed tray sensor 6.

The lifting motor 3 raises and lowers the paper feed tray 2.

The motor encoder 4 outputs a pulse signal for each specified rotation angle of the rotation shaft of the lift motor 3.

The paper presence sensor 5 detects whether or not paper P is present on the paper feed tray 2. The paper presence sensor 5 turns on when paper P is present on the paper feed tray 2, and turns off when paper P is not present on the paper feed tray 2.

The paper feed tray sensor 6 detects the detection plate 2b. The paper feed tray sensor 6 is positioned at a predetermined height.

The paper feed guide plate 7 is a member that regulates the position of the downstream end (right end) of the paper P on the paper feed tray 2. The paper feed guide plate 7 is located near the downstream side of the paper feed tray 2 and below the downstream end of the belt unit 51, which will be described later.

As shown in Figures 3 and 4, the paper feed guide plate 7 has a cutout 7a formed in the upper center in the front-to-rear direction to allow air to be blown from the main floating mechanism 21 (described later) to the paper P on the paper feed tray 2.

The separation gate 8 is a member that blocks the paper P other than the topmost paper P adsorbed to the transport section 13 among the paper P floated by the floating section 11. Two separation gates 8 are installed in the forward and backward directions, spaced apart from each other, near the lower downstream end of the transport section 13.

The side fences 9 are members that regulate the position of the paper P on the paper feed tray 2 in the front-to-rear direction (width direction). The two side fences 9 are arranged spaced apart from each other in the front-to-rear direction. The side fences 9 are inserted into the fence insertion holes 2a of the paper feed tray 2 and are configured to be movable in the front-to-rear direction within the range of the fence insertion holes 2a.

As shown in FIG. 5, the side fence 9 is formed with a side floating air outlet 16 and a side separation air outlet 17. Also, as shown in FIGS. 3 to 5, the side fence 9 is provided with a straightening member 18. Note that FIG. 5 is a view of the rear side fence 9 as seen from the front.

The side floating air outlet 16 is an outlet for the side floating airflow generated by the side floating mechanism 22 described later. The side separated air outlet 17 is an outlet for the side separated airflow generated by the side separation mechanism 42 described later.

The straightening member 18 is a member that attracts the topmost sheet P of the sheets P on the paper feed tray 2 that have been floated by the floating portion 11, and allows the side separation air current to flow between the topmost sheet P and the second sheet P from the top. The straightening member 18 is attached along the upper edge of the side separation air outlet 17 on the inner surface (paper feed tray 2 side) of the side fence 9. The straightening member 18 is inclined so that it becomes higher as it approaches the center of the paper feed tray 2 in the front-to-rear direction.

The end fence 10 is a member that regulates the position of the upstream end (left end) of the paper P on the paper feed tray 2. The end fence 10 is disposed above the paper feed tray 2. The end fence 10 is configured to be movable in the left-right direction.

The floating unit 11 blows air onto the paper P on the paper feed tray 2 to float the paper P. The floating unit 11 includes a main floating mechanism unit 21 and two side floating mechanisms 22.

The main floating mechanism 21 blows air from the downstream side onto the paper P on the paper feed tray 2 to float the paper P. The main floating mechanism 21 is disposed near the downstream side of the paper feed tray 2. The main floating mechanism 21 includes a main floating fan 26, a shutter 27, and two main floating air outlets 28.

The main levitation fan 26 blows air from downstream onto the paper P on the paper feed tray 2, generating a main levitation airflow to lift the paper P.

The shutter 27 switches on and off the blowing of the main floating air current from the main floating air outlet 28. When the main floating fan 26 is running, the main floating air current blows out from the main floating air outlet 28 when the shutter 27 is open, and the blowing of the main floating air current from the main floating air outlet 28 is stopped when the shutter 27 is closed.

The main floating air outlet 28 is an outlet for the main floating airflow generated by driving the main floating fan 26. The two main floating air outlets 28 are arranged spaced apart from each other in the front-to-rear direction near the lower downstream end of the conveying section 13.

The two side lifting mechanisms 22 are arranged at a distance from each other in the front-rear direction, sandwiching the paper feed tray 2. The two side lifting mechanisms 22 are installed on the outside of each of the two side fences 9.

The front side floating mechanism 22 blows air onto the paper P on the paper feed tray 2 from the front side to float the paper P. The rear side floating mechanism 22 blows air onto the paper P on the paper feed tray 2 from the rear side to float the paper P. The side floating mechanism 22 includes a side floating fan 31 and a shutter 32.

The side floating fan 31 blows air from the side floating air outlet 16 of the side fence 9 onto the paper P on the paper feed tray 2, generating a side floating air current to float the paper P.

The shutter 32 switches on and off the blowing of the side floating air current from the side floating air outlet 16. When the side floating fan 31 is running, if the shutter 32 is open, the side floating air current blows out from the side floating air outlet 16, and if the shutter 32 is closed, the blowing of the side floating air current from the side floating air outlet 16 is stopped.

The separation unit 12 separates the topmost sheet P from the sheets P floated by the floating unit 11. The separation unit 12 includes a main separation mechanism unit 41 and two side separation mechanism units 42.

The main separation mechanism 41 blows air from the downstream side between the topmost sheet P that has been floated by the floating portion 11 and adsorbed to the transport portion 13 and the second sheet P from the top. The main separation mechanism 41 includes a main separation fan 46 and two main separation air outlets 47.

The main separation fan 46 blows air from the downstream side between the topmost sheet P and the second topmost sheet P adsorbed to the conveying section 13, generating a main separation airflow to separate the topmost sheet P from the second topmost sheet P and the following sheets P.

The main separation air outlet 47 is an outlet for the main floating air current generated by driving the main separation fan 46. The two main separation air outlets 47 are arranged spaced apart from each other in the front-to-rear direction near the lower downstream end of the conveying section 13. The main separation air outlet 47 blows air upward toward the conveying section 13.

The two side separation mechanism units 42 are arranged spaced apart from each other in the front-rear direction, sandwiching the paper feed tray 2. The two side separation mechanism units 42 are installed on the outside of the two side fences 9, one each. The side separation mechanism unit 42 is arranged adjacent to the right side of the side lift mechanism unit 22.

The side separation mechanism 42 draws the topmost sheet P of the sheets P floated by the floating portion 11 to the straightening member 18, and blows out a side separation airflow from the side separation air outlet 17 of the side fence 9 to separate the topmost sheet P from the second sheet P from the top. The side separation mechanism 42 is equipped with a side separation fan 48 that generates a side separation airflow.

The conveying unit 13 conveys the topmost sheet P of the sheets P floated by the floating unit 11 by suctioning it with air. The conveying unit 13 includes two belt units 51, a conveying motor 52, a chamber 53, and a suction fan 54.

The belt unit 51 attracts and holds the paper P and transports it. The two belt units 51 are arranged side by side in the front-to-rear direction. The belt unit 51 is arranged straddling the right end of the paper feed tray 2 in the left-to-right direction. The belt unit 51 includes a transport belt 56, a drive roller 57, and a driven roller 58.

The conveyor belt 56 is a circular belt that is stretched over a drive roller 57 and a driven roller 58. A plurality of belt holes 56a are formed around the entire circumference of the conveyor belt 56. The conveyor belt 56 attracts and holds the paper P on the conveying surface 56b, which is the lower surface of the conveyor belt 56, by the suction force generated in the belt holes 56a by the drive of the suction fan 54. With the paper P attracted and held, the conveyor belt 56 rotates (endless movement) by the drive of the drive roller 57, and the paper P is conveyed.

The drive roller 57 rotates (endlessly moves) the conveyor belt 56. The drive rollers 57 of the two belt units 51 are connected to each other by a shaft 59.

The driven roller 58 supports the conveyor belt 56 together with the drive roller 57. The driven roller 58 rotates in response to the rotation of the conveyor belt 56. The driven rollers 58 of the two belt units 51 are connected to each other by a shaft 60.

The conveyor motor 52 rotates the drive roller 57 by rotating the shaft 59.

The chamber 53 forms a negative pressure chamber for generating an adhesive force in the belt holes 56a of the belt unit 51. The chamber 53 holds the belt unit 51 inside so that the conveying surface 56b of the conveyor belt 56 is exposed. An air vent (not shown) is formed in the portion of the bottom plate of the chamber 53 through which the conveyor belt 56 passes. An adhesive force is generated in the belt holes 56a by the air being sucked into the chamber 53 through the belt holes 56a in the conveying surface 56b of the conveyor belt 56 and the air vent in the chamber 53.

The suction fan 54 exhausts air from the chamber 53. When the suction fan 54 exhausts air from the chamber 53, air is sucked into the chamber 53 from outside the chamber 53 through the belt holes 56a in the conveying surface 56b of the conveyor belt 56 and the ventilation holes in the chamber 53. The suction fan 54 is located above the chamber 53.

The upper limit sensor 14 is for detecting whether the topmost sheet P of paper P stacked on the paper feed tray 2 is at a predetermined paper upper limit position (target position). The upper limit sensor 14 is disposed downstream of the paper feed tray 2 at a height position where it can detect floating paper P in the floating area, which is the area in the vertical direction where the floating part 11 floats the paper P. The upper limit of the detection range of the upper limit sensor 14 is lower than the upper limit of the floating area, and the lower limit of the detection range is higher than the lower limit of the floating area. The upper limit sensor 14 is made of a reflective optical sensor.

The control unit 15 controls the operation of the entire paper feeder 1. The control unit 15 is configured with a CPU, RAM, ROM, a hard disk, etc.

Specifically, the control unit 15 controls the driving of the floating unit 11 and the separation unit 12 to float the paper P on the paper feed tray 2, adsorb the topmost paper P to the transport surface 56b, and transport and feed the paper by the transport unit 13. At this time, the control unit 15 controls the blowing of air by the floating unit 11 to the paper P for each sheet of paper that is adsorbed to the transport surface 56b of the transport unit 13, in order to separate the topmost paper P from the second and subsequent sheets of paper P, as described below. In addition, in normal mode control, the control unit 15 performs upper limit tracking control to raise the paper feed tray 2 in accordance with the reduction in the remaining amount of paper P on the paper feed tray 2 due to paper feeding, and maintain the height position of the topmost paper P on the paper feed tray 2, i.e., the height position of the top surface of the paper stack PT consisting of multiple sheets of paper P on the paper feed tray 2, at the paper upper limit position (target position).

The paper upper limit position (target position) is preset as the height position of the top surface of the paper stack PT that is appropriate for paper feeding in the paper feeder 1. The paper upper limit position is set to an appropriate position according to the paper type (paper thickness) based on experiments, etc.

In the upper limit tracking control in the normal mode control, the control unit 15 acquires the sensor value of the upper limit sensor 14 while the paper P is floating by the floating unit 11, and raises the paper feed table 2 when the acquired sensor value is less than a predetermined tracking threshold.

The sensor value of the paper P floated by the floating portion 11 while it is floating is the amount of reflected light received from the edge of the floating paper P that is within the detection range of the upper limit sensor 14. Therefore, the sensor value of the paper P while it is floating increases as the number of floating sheets of paper P within the detection range of the upper limit sensor 14 increases.

The number of sheets of paper P that can be floated by the air blown by the floating part 11 is the number of sheets of paper P that are within the floating area. Therefore, the lower the height position of the top surface of the paper stack PT when the paper P on the paper feed tray 2 is not floating, the fewer the number of sheets of paper P that can be floated by the air blown by the floating part 11.

Because of this, the sensor value while the paper P is floating can be used as information indicating the height position of the top surface of the paper stack PT on the paper feed table 2 if the paper P on the paper feed table 2 were not floating. If the height position of the paper feed table 2 does not change, the amount of floating paper P decreases as paper feeding progresses, and the sensor value tends to decrease.

Therefore, as described above, the paper feeder 1 performs upper limit tracking control using the sensor value while the paper P is floating.

In addition, as described below, after starting the paper feeding operation using normal mode control, the paper feeding device 1 determines the tracking threshold by sampling the sensor value while the paper P is floating, and starts the upper limit tracking control. This is to set the tracking threshold according to the actual paper size, paper type, paper color, etc. during the paper feeding operation, and to prevent a decrease in the accuracy of the upper limit tracking control.

In addition, in the paper feeder 1, the control unit 15 performs last mode control in the final stage of feeding the paper P on the paper feed tray 2. Last mode control fixes the paper feed tray 2 to a predetermined final height position (corresponding to a predetermined height position) according to the paper attributes (corresponding to the attributes of the sheet) when the remaining amount of paper on the paper feed tray 2 is within a specified remaining amount range, and controls the wind speed of the floating unit 11 according to the specified remaining amount range, the final height position, and the paper attributes. In last mode control, the control unit 15 also controls the wind speed and floating on time of the separation unit 12 according to the specified remaining amount range, the final height position, and the paper attributes.

Here, the floating on time is the on time per sheet of paper in the on/off control of the blowing of air onto the paper P by the floating part 11. The paper attributes consist of a combination of the paper type and the paper size.

The final height position is preset as the height position of the paper feed tray 2 during last mode control. When the paper feed tray 2 is at the final height position, all of the paper P on the paper feed tray 2 is within the floating area created by the floating part 11. The specified remaining amount range is preset as the range of remaining paper on the paper feed tray 2 at the final height position at the start of last mode control.

The final height position and the specified remaining amount range are set so that at the start of last mode control, the amount of remaining paper is neither too much nor too little relative to the distance between the conveying surface 56b and the paper feed tray 2.

Here, if there is too much remaining paper in relation to the distance between the transport surface 56b and the paper feed tray 2, the topmost sheet P cannot be sufficiently separated from the second and subsequent sheets P from the top, and there is a risk of double feeding of the sheets P. Also, if there is too little remaining paper in relation to the distance between the transport surface 56b and the paper feed tray 2, the air volume per sheet increases, making the behavior of the sheets P more likely to become erratic when floating up. If the behavior of the sheets P becomes erratic, multiple sheets P may be attracted to the transport surface 56b, causing double feeding, or the sheets P may climb over the end fence 10, causing empty feeding.

In addition, the lighter the paper type, the more likely it is that the behavior of the paper P will be disturbed when it floats up. In addition, the smaller the paper size, the more likely it is that the behavior of the paper P will be disturbed when it floats up. In addition, the higher the wind speed at the floating section 11, the more likely it is that the behavior of the paper P will be disturbed when it floats up. In addition, the higher the wind speed at the separation section 12, the more likely it is that the behavior of the paper P will be disturbed when it floats up. In addition, the longer the floating on time, the more likely it is that the behavior of the paper P will be disturbed when it floats up.

In addition, if the remaining amount of paper is the same, the greater the distance between the transport surface 56b and the paper feed tray 2 at the final height position, the greater the air volume per sheet of paper, making it more likely that the behavior of the paper P will be disturbed when it floats up.

The final height position, last mode floating wind speed, last mode separation wind speed, and last mode floating on time are set according to the paper attributes. Here, the last mode floating wind speed is the wind speed of the floating part 11 in the last mode control. The last mode separation wind speed is the wind speed of the separation part 12 in the last mode control. The last mode floating on time is the floating on time in the last mode control.

Specifically, if the paper size is the same, the lighter the paper type, the higher the final height position, the smaller the last mode floating wind speed and last mode separation wind speed, and the shorter the last mode floating on time is set. Also, if the paper type is the same, the smaller the paper size, the higher the final height position, the smaller the last mode floating wind speed and last mode separation wind speed, and the shorter the last mode floating on time is set.

The last mode floating wind speed, last mode separation wind speed, and last mode floating on time according to the paper attributes are set according to the specified remaining amount range and the final height position. In other words, the last mode floating wind speed, last mode separation wind speed, and last mode floating on time according to the paper attributes are set to values that allow the paper P to be separated one by one while the paper feed tray 2 is at the final height position until the paper P of the specified remaining amount range has been fed, and that suppress disturbance in the behavior of the paper P when it floats up.

The last mode floating wind speed, last mode separation wind speed, and last mode floating on time according to the paper attributes are set to values less than the wind speed of the floating part 11, the wind speed of the separation part 12, and the floating on time during normal paper feed control (normal mode control). Here, the wind speed of the floating part 11, the wind speed of the separation part 12, and the floating on time during normal mode control are set according to the paper attributes. The last mode floating wind speed, last mode separation wind speed, and last mode floating on time are determined, for example, experimentally.

However, depending on the final height position, the gap between the transport surface 56b and the paper feed tray 2 is narrow, so that the paper P on the paper feed tray 2 may be sucked onto the transport surface 56b at an unintended timing. To prevent this, the last mode suction wind speed, which is the suction wind speed of the transport section 13 during last mode control, is set according to the final height position. The last mode suction wind speed is set to a value at which the paper P that has not floated on the paper feed tray 2 at the final height position is not sucked onto the transport surface 56b. The last mode suction wind speed is set to a value equal to or lower than the suction wind speed of the transport section 13 during normal mode control. The last mode suction wind speed is determined, for example, experimentally.

The control unit 15 also determines whether to perform last follow-up mode control based on the paper attributes, and if it determines to perform last follow-up mode control, performs last follow-up mode control immediately before last follow-up mode control. The last follow-up mode control is a control that raises the paper feed tray 2 by a specified lift amount according to the paper attributes each time the paper P on the paper feed tray 2 decreases by the number of sheets (corresponding to a specified number of sheets) according to the paper attributes until the paper feed tray 2 reaches the final height position. The last follow-up mode control is performed to make the paper feed tray 2 reach the final height position according to the paper attributes when the remaining amount of paper on the paper feed tray 2 is within the specified remaining amount range.

Whether or not to perform last follow mode control is determined in advance for each paper attribute. For example, last follow mode control is performed when the final height position according to the paper attribute is higher than the normal final height position, which is the height position at which the rise of the paper feed tray 2 stops with upper limit follow control in normal mode control. Also, last follow mode control is performed even if the final height position according to the paper attribute is lower than the normal final height position, in which case if the paper feed tray 2 is allowed to reach the final height position with upper limit follow control in normal mode control, the remaining amount of paper at that point is so small that disturbance in the behavior of the paper P when it floats up would occur.

The height position of the paper feed tray 2 at the start of last-follow mode control, as well as the number of sheets fed and the specified amount of lift in last-follow mode control, are set according to the paper attributes so that there is no disruption in the behavior of the paper P when it floats during last-follow mode control, and the paper feed tray 2 reaches its final height position when the amount of paper remaining on the paper feed tray 2 is within the specified remaining amount range.

The control unit 15 stores the last mode table 61 shown in FIG. 6. The last mode table 61 is a table that associates paper attributes (paper type and paper size), the number of transition pulses, the number of stop pulses, the number of sheets fed in the upward direction, the number of upward pulses, the last mode floating wind speed, the last mode separation wind speed, the last mode suction wind speed, and the last mode floating on time.

In the case of paper attributes that perform last follow mode control, the number of transition pulses is the number of output pulses of the motor encoder 4 from when the paper feed tray sensor 6 detects the detected plate 2b until the transition from normal mode control to last follow mode control. In the case of paper attributes that do not perform last follow mode control, the number of transition pulses is the number of output pulses of the motor encoder 4 from when the paper feed tray sensor 6 detects the detected plate 2b until the transition from normal mode control to last mode control.

The number of stop pulses is the number of output pulses from the motor encoder 4 from when the paper feed tray sensor 6 detects the detection plate 2b until the paper feed tray 2 is stopped at the final height position. In the case of paper attributes that do not perform last follow mode control, the number of transition pulses and the number of stop pulses are the same.

The number of lift pulses is the number of output pulses from the motor encoder 4 for the above-mentioned specified lift amount when the lift motor 3 is driven at a preset duty ratio in last-follow mode control.

In FIG. 6, paper attributes that do not have values for the number of sheets fed to rise and the number of rise pulses do not require last follow mode control.

Next, we will explain the operation of the paper feeder 1.

Here, it is assumed that at the start of the paper feed operation, the paper feed tray 2 is at a height position lower than the height position at which the paper feed tray sensor 6 detects the detection plate 2b. It is also assumed that all the paper P on the paper feed tray 2 is fed.

When the start of paper feeding is instructed, the control unit 15 starts the paper feeding operation in normal mode control. Specifically, the control unit 15 starts raising the paper feed tray 2 from a state in which the topmost paper P (the top surface of the paper stack PT) among the papers P stacked on the paper feed tray 2 is below the lower limit of the detection range of the upper limit sensor 14.

After the paper feed tray 2 starts to rise, when the top end of the paper stack PT on the paper feed tray 2 comes within the detection range of the upper limit sensor 14, the upper limit sensor 14 starts to receive reflected light from the right side of the top end of the paper stack PT. Then, as the paper feed tray 2 rises, the area of the paper stack PT on the paper feed tray 2 that is within the detection range of the upper limit sensor 14 expands, and the sensor value (amount of received light) of the upper limit sensor 14 increases.

When the control unit 15 determines that the sensor value has reached a predetermined non-floating threshold, it stops the rise of the paper feed tray 2. Here, the non-floating threshold is set as the sensor value when the height position of the top surface of the paper stack PT is at a predetermined sensor position within the detection range of the upper limit sensor 14. Therefore, by stopping the rise of the paper feed tray 2 when the sensor value reaches the non-floating threshold as described above, the paper feed tray 2 stops at a height position where the top surface of the paper stack PT is at the above-mentioned sensor position.

Next, the control unit 15 starts raising or lowering the paper feed tray 2, and stops the paper feed tray 2 when the top surface of the paper stack PT reaches a specified paper feed start position. This sets the height position of the top surface of the paper stack PT to the paper feed start position. Here, the control unit 15 determines whether the top surface of the paper stack PT has reached the paper feed start position based on the number of output pulses from the motor encoder 4 from the point when the paper feed tray 2 starts to rise or fall.

The paper feed start position is higher than the paper upper limit position described above, which is the target position for the top surface of the paper stack PT during the paper feed operation. Specifically, the paper feed start position is higher than the paper upper limit position (target position) by the thickness of the paper P for the total number of sheets excluded from sampling, described below, and half the number of sheets sampled, described below.

The control unit 15 then starts driving the main levitation fan 26, the two side levitation fans 31, the main separation fan 46, the two side separation fans 48, and the suction fan 54. The shutter 27 and the two shutters 32 are both in the open state.

As a result, a main floating airflow is blown out from the main floating air outlet 28, a side floating airflow is blown out from the side floating air outlet 16, a main separated airflow is blown out from the main separated air outlet 47, and a side separated airflow is blown out from the side separated air outlet 17. Also, an adhesive force is generated in the belt hole 56a of the belt unit 51.

Here, the control unit 15 controls the main floating fan 26, the side floating fan 31, the main separation fan 46, and the side separation fan 48 so that the wind speed of the floating unit 11 (wind speed of the main floating airflow and the side floating airflow) and the wind speed of the separation unit 12 (wind speed of the main separation airflow and the side separation airflow) become the wind speeds for normal mode control, respectively, according to the paper attributes. The control unit 15 also controls the suction fan 54 so that the suction wind speed of the transport unit 13 becomes the suction wind speed for normal mode control.

As shown in FIG. 7, the main floating air current and the side floating air current cause the uppermost sheets of paper P on the paper feed tray 2 to float, and the uppermost sheet P of the floating sheets P is adsorbed to the conveying surface 56b of the belt unit 51.

When the paper P floats up, the side separation air current blown out from the side separation air outlet 17 flows along the straightening member 18 near the side fence 8, creating a negative pressure state between the straightening member 18 and the topmost paper P. This causes the topmost paper P to be drawn toward the straightening member 18 and come into contact with it. As a result, the side separation air current flows between the topmost paper P and the second topmost paper P.

On the other hand, on the main separation mechanism 41 side, after the topmost sheet P is adsorbed onto the transport surface 56b, the main separation airflow blown out from the main separation air outlet 47 flows upstream (to the left) along the topmost sheet P adsorbed onto the transport surface 56b.

As a result, the main separation airflow, the side separation airflow from the front, and the side separation airflow from the rear collide between the topmost sheet P and the second-highest sheet P, generating positive pressure.

In this state, the control unit 15 controls the shutter 27 and the two shutters 32 to close. After the shutters 27 and 32 are completely closed, the control unit 15 controls the conveying motor 52 to start driving the belt unit 51.

When the belt unit 51 starts to drive, the topmost sheet P adsorbed to the transport surface 56b starts to be transported to the right.

In addition, by closing the shutters 27, 32, the blowing of the main floating air current from the main floating air outlet 28 onto the paper P on the paper feed tray 2 and the blowing of the side floating air current from the side floating air outlet 16 are stopped. In other words, the blowing of air by the floating part 11 onto the paper P on the paper feed tray 2 is turned off (stopped). As a result, the positive pressure between the topmost paper P and the second paper P from the top pushes down the second and subsequent sheets of paper P, separating the topmost paper P from the second and subsequent sheets of paper P. The second and subsequent sheets of paper P fall onto the papers P remaining on the paper feed tray 2.

As described above, the topmost sheet P is transported by the belt unit 51 while the second and subsequent sheets P fall from the top. When the sheets P have finished falling, the sheets P other than the sheet P being transported by the belt unit 51 return to their stacked state on the sheet feed tray 2.

Next, the control unit 15 stops the belt unit 51 at a predetermined timing after the belt unit 51 starts to drive. After this, the control unit 15 opens the shutter 27 and the two shutters 32 to feed the next paper P, and floats the uppermost sheets of paper P on the paper feed tray 2.

By repeating the above operation, the paper P is fed sequentially from the paper feed device 1 to the paper feed destination. Here, the control unit 15 controls the opening and closing of the shutters 27, 32 so that the opening time of the shutters 27, 32 per sheet of paper fed is the floating on time for normal mode control.

After the paper feeding operation starts, when the number of fed sheets reaches the sampling exclusion number, the control unit 15 starts sampling the sensor value to determine the tracking threshold.

Here, the sampling exclusion number is preset as the number of sheets fed for which sampling of the sensor value to determine the tracking threshold is not performed immediately after the start of the paper feed operation. As described below, immediately after the start of the paper feed operation, the behavior of the paper P when it is floated is unstable, so the sampling exclusion number is set and sampling of the sensor value is not performed until that number of sheets have been fed. The behavior of the paper P when it is floated differs depending on the paper attributes, so the sampling exclusion number is set according to the paper attributes. The sampling exclusion number may be one sheet or multiple sheets.

When the above-mentioned sampling is started, the control unit 15 acquires the sensor value of the upper limit sensor 14 while the paper P is floating up to feed the next paper P after the last paper P of the number of sheets excluded from sampling. After this, the control unit 15 acquires the sensor value while the floating paper P is floating up for each sheet of paper transported (fed) by the transport unit 13. As the sensor value while the paper P is floating up, the control unit 15 acquires, for example, the sensor value a predetermined time after the shutters 27, 32 are opened.

When the sensor values for the number of sampled sheets have been acquired, the control unit 15 determines a tracking threshold and starts upper limit tracking control. Specifically, the control unit 15 calculates the average value of the sensor values for the acquired number of sampled sheets, and determines the calculated average value as the tracking threshold. The control unit 15 then starts upper limit tracking control using the determined tracking threshold. Until the upper limit tracking control starts, the height position of the paper feed tray 2 is fixed at the position set at the start of the paper feed operation.

The number of samples is a preset number of sheets fed for sampling the sensor value to determine the tracking threshold. The number of samples is multiple sheets. The number of samples can be a common value regardless of the paper attributes, or the value can be changed depending on the paper attributes.

The sampling period, which is the period during which the sensor values for the number of sampled sheets are acquired, is set so that the same number of sheets are fed both before and after the point at which the height position of the top surface of the paper stack PT reaches the upper paper limit position (target position).

After upper limit tracking control starts, the paper feed tray 2 rises in response to the decrease in the amount of paper remaining on the paper feed tray 2 due to paper feeding.

In the paper feed device 1, the aforementioned last mode control is performed in the final stage of feeding the paper P on the paper feed tray 2. Depending on the paper attributes, last follow-up mode control is performed prior to the last mode control. This paper feed control in the final stage will be explained with reference to the flowchart in Figure 8.

After the paper feed operation starts, in step S1 of FIG. 8, the control unit 15 determines whether the paper feed tray sensor 6 is turned on. Here, the paper feed tray sensor 6 is turned on when it detects the detection target plate 2b. If it is determined that the paper feed tray sensor 6 is not turned on (step S1: NO), the control unit 15 repeats step S1.

If it is determined that the paper feed tray sensor 6 is on (step S1: YES), in step S2, the control unit 15 starts counting the number of output pulses from the motor encoder 4.

Next, in step S3, the control unit 15 determines whether the count value of the number of output pulses from the motor encoder 4 has reached the number of transition pulses corresponding to the paper attributes of the paper P being fed. If it is determined that the count value has not reached the number of transition pulses (step S3: NO), the control unit 15 repeats step S3.

If it is determined that the count value has reached the number of transition pulses (step S3: YES), in step S4, the control unit 15 determines whether or not to perform last follow mode control based on the paper attributes of the paper P being fed.

If it is determined that last tracking mode control should be performed (step S4: YES), in step S5, the control unit 15 transitions from normal mode control to last tracking mode control.

In the last follow mode control, the control unit 15 does not perform upper limit follow control using the upper limit sensor 14 described above, but instead forcibly raises the paper feed tray 2 by a specified lift amount each time the paper P on the paper feed tray 2 decreases by the lift feed number according to the paper attributes of the paper P being fed. Specifically, the control unit 15 drives the lift motor 3 by the number of lift pulses at a preset duty ratio each time the lift feed number of paper P is fed.

After starting the last tracking mode control, the control unit 15 determines whether the count value of the number of output pulses of the motor encoder 4 since the paper feed tray sensor 6 turned on has reached the number of stop pulses corresponding to the paper attributes of the paper P being fed. If it is determined that the count value has not reached the number of stop pulses (step S6: NO), the control unit 15 repeats step S6.

If it is determined that the count value has reached the stop pulse number (step S6: YES), in step S7, the control unit 15 transitions from last tracking mode control to last mode control.

Specifically, the control unit 15 stops the raising of the paper feed tray 2 when the count value reaches the number of stop pulses. This causes the paper feed tray 2 to stop at the final height position according to the paper attributes. After this, the paper feed tray 2 is not raised any further.

The control unit 15 then controls the floating unit 11 and the separation unit 12 so that the wind speed of the floating unit 11 and the wind speed of the separation unit 12 become the last mode floating wind speed and the last mode separation wind speed, respectively, according to the paper attributes.

The control unit 15 also controls the opening and closing of the shutters 27 and 32 for each sheet of paper so that the floating on time is the last mode floating on time according to the paper attributes.

The control unit 15 also controls the suction fan 54 so that the suction wind speed of the conveying unit 13 becomes the last mode suction wind speed according to the final height position in the paper attributes of the paper P being fed.

If it is determined in step S4 that the last tracking mode control is not to be performed (step S4: NO), the control unit 15 proceeds to step S7 and transitions from normal mode control to last mode control. Here, in the case of a paper attribute for which the last tracking mode control is not performed, the number of transition pulses and the number of stop pulses are the same as described above, so the control unit 15 stops the lifting of the paper feed tray 2 when the count value reaches the number of transition pulses.

Next, in step S8, the control unit 15 determines whether or not feeding of the paper P on the paper feed tray 2 has been completed. Here, the control unit 15 determines that feeding of the paper P has been completed when the paper presence/absence sensor 5 turns off. If the control unit 15 determines that feeding has not been completed (step S8: NO), it repeats step S8. If the control unit 15 determines that feeding has been completed (step S8: YES), it ends the series of processes.

An example of the change in height position and remaining amount of paper on the paper feed tray 2 due to last follow mode control and last mode control is shown in Figure 9.

As a comparative example, FIG. 9 shows the transition of the height position of the paper feed tray 2 and the remaining amount of paper when normal paper feed control (normal mode control) is performed until feeding of all the paper P on the paper feed tray 2 is completed. In the paper feed device 1, when normal mode control is performed until feeding of all the paper P on the paper feed tray 2 is completed, the rise of the paper feed tray 2 stops at a predetermined normal final height position.

In the paper attributes example of Figure 9, the final height position in last mode control is higher than the normal final height position, so last follow mode control is performed.

Next, FIG. 10 shows an example of the change in height position of the paper feed tray 2 and the amount of remaining paper when transitioning from normal mode control to last mode control without performing last follow-up mode control.

In the paper attributes example of Figure 10, the final height position is lower than the normal final height position, so last tracking mode is not necessary and a transition is made from normal mode control to last mode control.

As described above, in the paper feeder 1, in last mode control, the control unit 15 fixes the paper feed tray 2 to a final height position according to the paper attributes when the remaining amount of paper on the paper feed tray 2 is within a specified remaining amount range, and controls the wind speed of the floating unit 11 according to the specified remaining amount range, the final height position, and the paper attributes.

This makes it possible to prevent the air volume per sheet of paper P from becoming too large when the paper P floats up, even in the final stage of paper feeding when the remaining paper is low. This makes it possible to suppress disturbances in the behavior of the paper P when it floats up. As a result, it is possible to reduce paper feeding problems such as multiple sheets of paper P being adsorbed to the transport surface 56b, and empty feeding when the paper P climbs over the end fence 10.

In addition, in the last mode control, the control unit 15 controls the wind speed and floating on time of the separation unit 12 according to the specified remaining amount range, the final height position, and the paper attributes. This makes it possible to further suppress disturbances in the behavior of the paper P when it floats up, thereby further reducing paper feeding problems.

In addition, in the last mode control, the control unit 15 sets the suction wind speed (last mode suction wind speed) of the conveying unit 13 according to the final height position, so that the paper P on the paper feed tray 2 is prevented from being sucked onto the conveying surface 56b at an unintended timing. This makes it possible to further reduce paper feeding problems such as double feeding.

In addition, in the paper feeder 1, the control unit 15 determines whether or not to perform last follow-up mode control based on the paper attributes. If it is determined that last follow-up mode control is to be performed, the control unit 15 performs last follow-up mode control immediately before last mode control. This makes it possible to suppress disturbances in behavior when the paper P floats up, while allowing the paper feed tray 2 to reach the final height position with the remaining paper amount within a specified remaining amount range, and to start last mode control. Here, if last follow-up mode control is not performed for paper attributes that require last follow-up mode control, it is not possible to fix the paper feed tray 2 at the final height position with the remaining paper amount within the specified remaining amount range and start last mode control, and there is a risk of disturbances in behavior when the paper P floats up. This can be prevented by performing last follow-up mode control.

[Second embodiment]
Next, a second embodiment, which is a partial modification of the first embodiment described above, will be described.

In the second embodiment, the control unit 15 is capable of executing low-remaining-amount mode control. Low-remaining-amount mode control is control that is performed during paper feed operation when the number of sheets P (loaded number Px) loaded on the paper feed tray 2 at the start of the paper feed operation (corresponding to the sheet supply operation) is equal to or less than a predetermined low-remaining-amount mode maximum number Pth (corresponding to a predetermined number of sheets) described later.

In the paper feeding operation in the low remaining amount mode control, the control unit 15 sets the wind speed of the floating unit 11, the wind speed of the separation unit 12, the floating on time, and the suction wind speed of the transport unit 13 to the same settings as in the last mode control. In addition, in this setting, the control unit 15 controls the height position of the paper feed table 2 according to the remaining amount of paper so that the paper can be fed while suppressing disturbance of the behavior of the paper P during floating and suppressing the suction of the paper P that has not been floated by the transport unit 13.

When the number of sheets P on the paper feed tray 2 is small at the start of the paper feed operation, the air volume per sheet becomes large when the paper P is floated by the floating portion 11, and the behavior of the paper P when it floats becomes unstable. This may prevent the calculation of the tracking threshold value by sampling in the normal mode control described above and the upper limit tracking control from being performed properly. This may result in paper feed problems such as double feeding and empty feeding. Therefore, in the second embodiment, when the number of sheets P on the paper feed tray 2 is small at the start of the paper feed operation, low remaining amount mode control is performed to reduce paper feed problems.

Next, the operation of the paper feeder 1 in the second embodiment will be described with reference to the flowcharts in Figs. 11 and 12. Here, it is assumed that all the papers P on the paper feed tray 2 are fed.

In step S11 in FIG. 11, the control unit 15 detects the number of sheets Px of paper P loaded on the paper feed tray 2 at the start of the paper feed operation.

Specifically, first, the control unit 15 starts the rise of the paper feed tray 2. Here, before the paper feed tray 2 starts to rise, the top surface of the paper stack PT is below the lower limit of the detection area of the upper limit sensor 14. Specifically, the paper feed tray 2 starts to rise from a predetermined rise start position where the top surface of the paper stack PT is below the lower limit of the detection area of the upper limit sensor 14 even when the paper feed tray 2 is full of paper P. When the control unit 15 starts to rise the paper feed tray 2, it starts counting the number of output pulses of the motor encoder 4.

After the paper feed tray 2 starts to rise, if the control unit 15 determines that the sensor value of the upper limit sensor 14 has reached the non-floating threshold value described above, it stops the paper feed tray 2 from rising. This stops the paper feed tray 2 at a height where the paper stack PT is at the sensor position.

Next, the control unit 15 calculates the height position Hpx of the paper feed tray 2 (or its upper surface) at that time from the count value of the number of output pulses from the motor encoder 4 at the time when the raising of the paper feed tray 2 is stopped.

Here, if the height position of the paper feed tray 2 (upper surface) when the paper feed tray 2 (upper surface) is at the sensor position is Hp0, and the thickness of the paper stack PT consisting of paper P with the number of loaded sheets Px is Wpx, the relationship between Hpx, Hp0, and Wpx is as shown in FIG. 13. In other words, the following formula (1) holds.

Hp0-Hpx=Wpx...(1)
Therefore, if the thickness of one sheet of paper P is Wp, the following formula (2) holds true.

Px=(Hp0-Hpx)/Wp...(2)
The control unit 15 calculates the number of stacked sheets Px using formula (2).

Here, Hp0 is a fixed value, and the control unit 15 stores Hp0 in advance. The control unit 15 also stores the thickness of one sheet of paper for each paper type in advance, and calculates the number of stacked sheets Px using the value of the thickness Wp of one sheet of paper corresponding to the paper type. The lift motor 3, motor encoder 4, upper limit sensor 14, and control unit 15 constitute a stacked sheet number detection unit.

Next, in step S12 of FIG. 11, the control unit 15 determines whether the number of sheets loaded Px exceeds the maximum number of sheets Pth for the low remaining amount mode.

Here, the low remaining amount mode maximum number of sheets Pth is set as a threshold value for determining whether or not to perform a paper feed operation in low remaining amount mode control. The low remaining amount mode maximum number of sheets Pth is set to a number that is sufficiently greater than the total number of sheets excluded from sampling and the number of sheets sampled, depending on the paper attributes.

If it is determined that Px>Pth (step S12: YES), in step S13, the control unit 15 starts the paper feed operation in the normal mode control described above. Here, if Px>Pth, the maximum number of sheets in the low remaining amount mode Pth is set so that the height position of the paper feed tray 2 when the top surface of the paper stack PT is at the paper feed start position at the start of the paper feed operation in the normal mode control is lower than the height position at which the paper feed tray sensor 6 detects the detection plate 2b.

When the paper feeding operation in normal mode control is started, the control unit 15 proceeds to step S14. The processes in steps S14 to S21 are the same as the processes in steps S1 to S8 in FIG. 8 described above. If the control unit 15 determines in step S21 that paper feeding has ended (step S21: YES), it ends the series of operations.

If it is determined in step S12 that Px≦Pth (step S12: NO), in step S22 of FIG. 12, the control unit 15 starts the paper feeding operation in the low remaining amount mode control.

Specifically, first, the control unit 15 sets the height position of the top surface of the paper stack PT to the low remaining paper feed start position, which is the height position at the start of the paper feed operation in the low remaining mode control.

Here, let Hpn be the height position of (the top surface of) the paper feed tray 2 when the remaining amount of paper P on the paper feed tray 2 in low remaining amount mode control is Pn. Also, let He be the height position (final height position) of (the top surface of) the paper feed tray 2 in last mode control, and Hs be the height position of (the top surface of) the paper feed tray 2 at the start of the paper feeding operation in low remaining amount mode control when the remaining amount Pn is the low remaining amount mode maximum number of sheets Pth. As shown in FIG. 14, Hpn is determined in the range from Hs to He according to the ratio of the remaining amount Pn to the low remaining amount mode maximum number of sheets Pth. That is, Hpn is expressed by the following formula (3). Also, Hs is expressed by the following formula (4).

Hpn=He-(He-Hs)×Pn/Pth...(3)
Hs=Hp0-Wpth-Ws...(4)
Here, Wpth is the thickness of the sheet stack PT consisting of the maximum number of sheets Pth in the low remaining mode. Ws is the offset amount of the top surface of the sheet stack PT from the sensor position to the low remaining sheet feed start position. 14, Hpth is the height of the sheet feed tray 2 (or its upper surface) when the upper surface of the sheet stack PT made up of the sheets P with the maximum number of sheets Pth in the low remaining amount mode is at the sensor position. It is the position.

The control unit 15 calculates the height position of the paper feed tray 2 (or its upper surface) when the top surface of the paper stack PT is at the low remaining paper feed start position by substituting the number of stacked sheets Px detected in step S1 into Pn in formula (3). The control unit 15 then raises and lowers the paper feed tray 2 so that the height position of the top surface of the paper stack PT moves from the sensor position to the low remaining paper feed start position. Ws is set so that the low remaining paper feed start position set in this way is higher than the paper feed start position in the normal mode control described above.

When the height position of the top surface of the paper stack PT is set to the low remaining paper feed start position, the control unit 15 starts driving the main levitation fan 26, the two side levitation fans 31, the main separation fan 46, the two side separation fans 48, and the suction fan 54. The shutter 27 and the two shutters 32 are both in the open state.

Here, from the start of the paper feeding operation, the control unit 15 controls the floating unit 11, the separation unit 12, and the suction fan 54 so that the wind speed of the floating unit 11 (wind speed of the main floating airflow and the side floating airflow), the wind speed of the separation unit 12 (wind speed of the main separation airflow and the side separation airflow), and the suction wind speed of the transport unit 13 are the same as the last mode floating wind speed, last mode separation wind speed, and last mode suction wind speed, respectively, according to the paper attributes of the paper P being fed.

Then, the control unit 15 performs the same on-off control as in the normal mode control for blowing air onto the paper P by the floating unit 11 (opening and closing control of the shutters 27, 32) and drive control of the belt unit 51 of the conveying unit 13. As a result, the paper P is fed sequentially from the paper feed device 1 to the paper feed destination.

Here, the control unit 15 controls the opening and closing of the shutters 27 and 32 so that the floating on time is the same as the last mode floating on time according to the paper attributes.

In addition, the control unit 15 raises the paper feed tray 2 in response to a decrease in the remaining amount of paper P on the paper feed tray 2 so that the height position of (the upper surface of) the paper feed tray 2 becomes the height position calculated by the above formula (3). This means that the control unit 15 raises the paper feed tray 2 so that the paper feed tray 2 reaches the final height position He when the paper P on the paper feed tray 2 runs out. At this time, the control unit 15 sets Pn to the value obtained by subtracting the number of sheets fed from the number of loaded sheets Px detected in step S1.

In the paper feeding operation under low remaining amount mode control, the wind speed of the floating section 11, the wind speed of the separation section 12, the floating on time, and the suction wind speed of the transport section 13 are set to the same settings as those in the last mode control, and the height position of the paper feed table 2 is controlled as described above, thereby preventing disturbances in the behavior of the paper P during floating and the suction of paper P that is not floating by the transport section 13.

After the start of the paper feeding operation in the low remaining amount mode control, in step S23 of FIG. 12, the control unit 15 determines whether or not the feeding of the number of loaded sheets Px detected in step S1 has been completed.

If it is determined that the feeding of the number of loaded sheets Px has not been completed (step S23: NO), in step S24, the control unit 15 determines whether or not there is paper P on the paper feed tray 2. Here, if the paper presence/absence sensor (corresponding to the sheet presence/absence detection unit) 5 is on, the control unit 15 determines that there is paper P on the paper feed tray 2. If it is determined that there is paper P on the paper feed tray 2 (step S24: YES), the control unit 15 returns to step S23. If it is determined that there is no paper P on the paper feed tray 2 (step S24: NO), the control unit 15 ends the series of operations.

Here, the number of loaded sheets Px detected in step S1 may include an error with respect to the actual number of loaded sheets. For this reason, the paper P on the paper feed tray 2 may run out before the feeding of the number of loaded sheets Px detected in step S1 is completed. If the actual number of loaded sheets at the start of the paper feeding operation is less than the number of loaded sheets Px detected in step S1, the paper P on the paper feed tray 2 will run out before the feeding of the number of loaded sheets Px detected in step S1 is completed, and step S24 will be judged as "NO".

If it is determined in step S23 that the feeding of the number of sheets Px has been completed (step S23: YES), in step S25, the control unit 15 determines whether or not there is paper P on the paper feed tray 2.

Here, if the actual number of loaded sheets at the start of the paper feed operation is greater than the number of loaded sheets Px detected in step S1, paper P will remain on the paper feed tray 2 even after the number of loaded sheets Px detected in step S1 has been fed.

If it is determined that there is no paper P on the paper feed tray 2 (step S25: NO), the control unit 15 ends the series of operations.

If it is determined that paper P is present on the paper feed tray 2 (step S25: YES), in step S26, the control unit 15 fixes the paper feed tray 2 at the final height position He and continues paper feeding. Here, as can be seen from the above formula (3), when the feeding of the number of loaded sheets Px detected in step S1 is completed, the paper feed tray 2 is at the final height position.

Next, in step S27, the control unit 15 determines whether or not there is paper P on the paper feed tray 2. If it is determined that there is paper P on the paper feed tray 2 (step S27: YES), the control unit 15 repeats step S27. If it is determined that there is no paper P on the paper feed tray 2 (step S27: NO), the control unit 15 ends the series of operations.

As described above, in the second embodiment, when the number of sheets P loaded on the paper feed tray 2 at the start of the paper feed operation is equal to or less than the maximum number Pth of sheets in the low remaining amount mode, the control unit 15 executes the paper feed operation under low remaining amount mode control. In the paper feed operation under low remaining amount mode control, the control unit 15 sets the wind speed of the floating unit 11, the wind speed of the separation unit 12, the floating on time, and the suction wind speed of the transport unit 13 to the same settings as those in the last mode control. In addition, in this setting, the control unit 15 controls the height position of the paper feed tray 2 according to the remaining amount of paper so as to suppress disturbance of the behavior of the paper P during floating and suppress the suction of the paper P that has not floated by the transport unit 13. As a result, even if the number of sheets P on the paper feed tray 2 at the start of the paper feed operation is small, disturbance of the behavior of the paper P during floating and the suction of the paper P that has not floated by the transport unit 13 can be suppressed. As a result, paper feed problems can be reduced.

In addition, in the low remaining amount mode control, if the paper presence/absence sensor 5 detects that paper P is present on the paper feed tray 2 when the feeding of the number of stacked sheets Px detected at the start of the paper feed operation is completed, the control unit 15 fixes the paper feed tray 2 to the final height position He from that point onwards. As a result, even if paper P remains on the paper feed tray 2 when the paper feed tray 2 reaches the final height position He due to an error in the detected number of stacked sheets Px, the paper feed operation is performed thereafter using the same control as the last mode control, thereby preventing paper feed problems.

[Other embodiments]
As described above, the present invention has been described by the first and second embodiments, but the descriptions and drawings forming part of this disclosure should not be understood as limiting the present invention. Various alternative embodiments, examples and operating techniques will become apparent to those skilled in the art from this disclosure.

In the first and second embodiments described above, the final height position and the last mode floating wind speed are set according to the paper attributes. However, if disturbances in the behavior of the paper P when it floats can be suppressed, the final height position and the last mode floating wind speed may be set regardless of the paper attributes. Even in this case, in the last mode control, by fixing the paper feed tray 2 to a predetermined final height position when the remaining amount of paper on the paper feed tray 2 is within a specified remaining amount range, and controlling the wind speed of the floating part 11 according to the specified remaining amount range and the final height position, it is possible to reduce paper feeding problems caused by disturbances in the behavior of the paper P when it floats.

In the first and second embodiments described above, the last mode separation wind speed and the last mode floating on time are set according to the paper attributes. However, at least one of the last mode separation wind speed and the last mode floating on time may be set regardless of the paper attributes. Even in this case, in the last mode control, by controlling at least one of the last mode separation wind speed and the last mode floating on time according to the specified remaining amount range and the final height position, it is possible to reduce disturbance in the behavior of the paper P when it floats up.

In addition, at least one of the wind speed and the floating on time of the separation unit 12 may be set to the same value in the last mode control as in the normal mode control. The same applies to the suction wind speed of the transport unit 13.

In addition, in the first and second embodiments described above, the paper attributes consist of a combination of paper type and paper size, but this is not limited to this, and the paper attributes may consist of, for example, only either paper type or paper size.

In addition, in the last follow-up mode control, the wind speed of the floating part 11 may be changed in stages from the wind speed of the floating part 11 in the normal mode control to the last mode floating wind speed. The same applies to the wind speed of the separation part 12.

In the second embodiment described above, in the low remaining amount mode control, the wind speed of the floating part 11, the wind speed of the separation part 12, the floating on time, and the suction wind speed of the transport part 13 are set to the same settings as those in the last mode control. In this setting, the height position of the paper feed table 2 is controlled according to the remaining amount of paper so that the paper can be fed while suppressing disturbance of the behavior of the paper P during floating and suppressing the suction of the paper P that is not floating by the transport part 13.

However, this is not limited to the above, and the low remaining amount mode control may be any control that raises the paper feed tray 2 in response to a decrease in the remaining amount of paper, sets the wind speed of the floating portion 11, the wind speed of the separation portion 12, and the floating on time to values that suppress disturbance of the behavior of the floating paper P, and sets the suction wind speed of the transport portion 13 to a value that suppresses suction of the paper P that is not floating.

In addition, in low remaining amount mode control, even if at least one of the wind speed of the separation section 12 and the floating on time is set to the same as in normal mode control, it is sufficient that the wind speed of the floating section 11 is set to suppress disturbance in the behavior of the paper P during floating.

In addition, in low remaining amount mode control, the suction wind speed of the conveying section 13 may be set to the same setting as in normal mode control.

The present invention can also be applied to devices that supply sheets other than paper.

As such, the present invention naturally includes various embodiments not described here. Therefore, the technical scope of the present invention is determined only by the invention-specific matters related to the scope of the claims that are appropriate from the above explanation.

[Additional Notes]
This application discloses the following inventions.

(Appendix 1)
A liftable loading platform on which sheets are loaded;
a floating unit that blows air onto the sheets stacked on the stacking table to lift the sheets;
a conveying section that conveys a topmost sheet among the sheets floated by the floating section;
a control unit that controls the lifting of the stacking tray in response to a decrease in the number of sheets remaining on the stacking tray,
The control unit of this sheet supplying device performs last mode control in which the loading platform is fixed at a predetermined height position when the remaining amount of sheets on the loading platform is within a specified remaining range, and the wind speed of the floating portion is controlled in accordance with the specified remaining range and the specified height position.

(Appendix 2)
The sheet supplying device according to claim 1, wherein the control unit sets the predetermined height position and the wind speed of the floating portion in the last mode control according to attributes of the sheet.

(Appendix 3)
The sheet lifting device further includes a separation unit that blows air between the topmost sheet and the second sheet from the top to separate the topmost sheet and the second sheet from the top of the sheets lifted by the lifting unit,
The sheet supplying device described in Appendix 1 or 2, characterized in that in the last mode control, the control unit controls at least one of the wind speed of the separation unit and the floating on time, which is the time for which air is blown by the floating unit for each sheet to be transported by the transport unit, in accordance with the specified remaining amount range and the specified height position.

(Appendix 4)
The sheet supplying device described in Appendix 3, characterized in that the control unit sets at least one of the wind speed of the separation unit and the floating on time, which are controlled in the last mode control according to the specified remaining amount range and the specified height position, according to the attributes of the sheet.

(Appendix 5)
The control unit, based on the attributes of the sheet,
determining whether to perform a last follow-up mode control for lifting the loading platform by a prescribed lift amount according to the attributes of the sheets each time the number of sheets on the loading platform is reduced by a prescribed number according to the attributes of the sheets until the loading platform reaches the predetermined height position;
5. The sheet supplying device according to claim 2, wherein when it is determined that the last follow-up mode control is to be performed, the last follow-up mode control is performed immediately before the last mode control.

(Appendix 6)
the conveying unit conveys the sheet by suction with air,
6. The sheet supplying device according to claim 1, wherein the control unit controls a suction wind speed of the conveying unit in accordance with the predetermined height position in the last mode control.

(Appendix 7)
The sheet supplying device described in Appendix 1 or 2, characterized in that when the number of sheets on the stacking tray at the start of the sheet supplying operation is equal to or less than a predetermined number, the control unit performs a low remaining amount mode control in the sheet supplying operation, in which the stacking tray is raised in accordance with the decrease in the remaining amount of sheets on the stacking tray and the wind speed of the floating section is set to a value that suppresses disturbance of the behavior of the sheets during floating.

(Appendix 8)
a stack number detection unit for detecting the number of sheets stacked on the stacking table;
a sheet presence/absence detection unit for detecting the presence or absence of a sheet on the loading platform,
The control unit is
When the number of sheets detected by the stack number detection unit at the start of the sheet supply operation is equal to or less than the predetermined number, it is determined that the low remaining amount mode control is to be performed;
In the low remaining amount mode control, the wind speed in the floating portion is set to the same wind speed as the wind speed in the last mode control,
a height position of the stacking table is controlled so that the stacking table reaches the predetermined height position when the supply of the number of sheets detected by the stacking number detection unit at the start of the sheet supply operation is completed;
The sheet supplying device described in Appendix 7 is characterized in that if the sheet presence/absence detection unit detects that there are sheets on the loading tray at the time when the supply of sheets of the number of sheets detected by the loaded number detection unit at the start of the sheet supply operation has been completed, the loading tray is fixed at the specified height position from that point onwards.

(Appendix 9)
The sheet lifting device further includes a separation unit that blows air between the topmost sheet and the second sheet from the top to separate the topmost sheet and the second sheet from the top of the sheets lifted by the lifting unit,
The control unit, in the low remaining capacity mode control,
Controlling the wind speed of the separation unit to a value that suppresses disturbance of the behavior of the floating sheet; and
The sheet supplying device described in Appendix 7 or 8 is characterized in that it performs at least one of the following controls: setting the floating on time, which is the time during which air is blown by the floating section for each sheet being transported to the transport section, to a value that suppresses disturbance of the behavior of the sheet during floating.

(Appendix 10)
the conveying unit conveys the sheet by suction with air,
The sheet supplying device according to any one of claims 7 to 9, characterized in that, in the low remaining amount mode control, the control unit sets the suction wind speed of the conveying unit to a value that suppresses suction of non-floating sheets.

REFERENCE SIGNS LIST 1 Paper feed device 2 Paper feed tray 3 Lifting motor 4 Motor encoder 5 Paper presence sensor 6 Paper feed tray sensor 7 Paper feed guide plate 8 Separation gate 9 Side fence 10 End fence 11 Floating section 12 Separation section 13 Transport section 14 Upper limit sensor 15 Control section 21 Main floating mechanism section 22 Side floating mechanism section 41 Main separation mechanism section 42 Side separation mechanism section 51 Belt unit 52 Transport motor 53 Chamber 54 Suction fan 61 Last mode table

Claims (10)

A liftable loading platform on which sheets are loaded;
a floating unit that blows air onto the sheets stacked on the stacking table to lift the sheets;
a conveying section that conveys a topmost sheet among the sheets floated by the floating section;
a control unit that controls the lifting of the stacking tray in response to a decrease in the number of sheets remaining on the stacking tray,
The control unit performs last mode control to fix the loading platform at a predetermined height position when the remaining amount of sheets on the loading platform is within a specified remaining amount range, and controls the wind speed of the floating part in a range lower than the wind speed of the floating part during normal paper feeding control in accordance with the specified remaining amount range and the specified height position. The sheet supplying device according to claim 1, characterized in that the control unit sets the predetermined height position and the wind speed of the floating part in the last mode control according to the attributes of the sheet. A liftable loading platform on which sheets are loaded;
a floating unit that blows air onto the sheets stacked on the stacking table to lift the sheets;
a conveying section that conveys a topmost sheet among the sheets floated by the floating section;
a separation unit that blows air between the topmost sheet and the second sheet from the top among the sheets floated by the floating unit, in order to separate the topmost sheet from the second sheet and the following sheets from the top ;
a control unit that controls the lifting of the stacking tray in response to a decrease in the number of sheets remaining on the stacking tray ,
The control unit is
a last mode control is performed in which the loading platform is fixed at a predetermined height position while the remaining amount of the sheets on the loading platform is within a specified remaining amount range, and the wind speed of the floating part is controlled in accordance with the specified remaining amount range and the specified height position;
A sheet supplying device characterized in that, in the last mode control, at least one of the wind speed of the separation section and the floating on time, which is the time during which air is blown by the floating section for each sheet to be transported to the transport section, is controlled in accordance with the specified remaining amount range and the specified height position. The sheet supplying device according to claim 3, characterized in that the control unit sets at least one of the wind speed of the separation unit and the floating on time, which are controlled in the last mode control according to the specified remaining amount range and the predetermined height position, according to the attributes of the sheet. A liftable loading platform on which sheets are loaded;
a floating unit that blows air onto the sheets stacked on the stacking table to lift the sheets;
a conveying section that conveys a topmost sheet among the sheets floated by the floating section;
a control unit that controls the lifting of the stacking tray in response to a decrease in the number of sheets remaining on the stacking tray,
The control unit is
a last mode control is performed in which the loading platform is fixed at a predetermined height position while the remaining amount of the sheets on the loading platform is within a specified remaining amount range, and the wind speed of the floating part is controlled in accordance with the specified remaining amount range and the specified height position;
setting the predetermined height position and the wind speed of the floating part in the last mode control according to the attributes of the sheet;
Based on the sheet attributes,
determining whether to perform a last follow-up mode control in which the loading platform is raised by a prescribed lift amount according to the attributes of the sheets each time the number of sheets on the loading platform is reduced by a prescribed number according to the attributes of the sheets until the loading platform reaches the predetermined height position;
2. The sheet supplying apparatus according to claim 1, wherein, when it is determined that the last follow-up mode control is to be performed, the last follow-up mode control is performed immediately before the last mode control. A liftable loading platform on which sheets are loaded;
a floating unit that blows air onto the sheets stacked on the stacking table to lift the sheets;
a conveying section that conveys a topmost sheet among the sheets floated by the floating section;
a control unit that controls the lifting of the stacking tray in response to a decrease in the number of sheets remaining on the stacking tray,
the conveying unit conveys the sheet by suction with air,
The control unit is
a last mode control is performed in which the loading platform is fixed at a predetermined height position while the remaining amount of the sheets on the loading platform is within a specified remaining amount range, and the wind speed of the floating part is controlled in accordance with the specified remaining amount range and the specified height position;
The sheet supplying device according to claim 1, wherein in the last mode control, a suction air speed of the conveying section is controlled in accordance with the predetermined height position. The sheet supplying device according to claim 1 or 2, characterized in that, when the number of sheets on the stacking tray at the start of the sheet supplying operation is equal to or less than a predetermined number, the control unit performs low-remaining-amount mode control in which, during the sheet supplying operation, the stacking tray is raised in accordance with the decrease in the remaining amount of sheets on the stacking tray, and the wind speed of the floating part is set to a value that suppresses disturbance of the behavior of the sheets during floating. A liftable loading platform on which sheets are loaded;
a floating unit that blows air onto the sheets stacked on the stacking table to lift the sheets;
a conveying section that conveys a topmost sheet among the sheets floated by the floating section;
a stack number detection unit for detecting the number of sheets stacked on the stacking table;
a sheet presence/absence detection unit for detecting the presence or absence of a sheet on the loading platform;
a control unit that controls the lifting of the stacking tray in response to a decrease in the number of sheets remaining on the stacking tray,
the control unit performs a last mode control in which the stacking platform is fixed at a predetermined height position when the remaining amount of the sheets on the stacking platform is within a specified remaining amount range, and the wind speed of the floating part is controlled in accordance with the specified remaining amount range and the specified height position,
In addition, the control unit
When the number of sheets detected by the stack number detection unit at the start of a sheet supply operation is equal to or less than a predetermined number, a low remaining amount mode control is performed in the sheet supply operation, in which the stacking table is raised in accordance with a decrease in the remaining amount of sheets on the stacking table, and a wind speed of the floating section is set to a value that suppresses disturbance of the behavior of the sheets being floated.
In the low remaining amount mode control, the wind speed in the floating portion is set to the same wind speed as the wind speed in the last mode control,
a height position of the stacking table is controlled so that the stacking table reaches the predetermined height position when the supply of the number of sheets detected by the stacking number detection unit at the start of the sheet supply operation is completed;
A sheet supplying device characterized in that, when the sheet presence/absence detection unit detects that there are sheets on the loading tray at the time when the supply of sheets of the number of sheets detected by the loaded number detection unit at the start of the sheet supply operation has been completed, the loading tray is fixed at the specified height position from that point onwards. The sheet lifting device further includes a separation unit that blows air between the topmost sheet and the second sheet from the top to separate the topmost sheet and the second sheet from the top of the sheets lifted by the lifting unit,
The control unit, in the low remaining capacity mode control,
Controlling the wind speed of the separation unit to a value that suppresses disturbance of the behavior of the floating sheet; and
The sheet supplying device according to claim 7 or 8, characterized in that at least one of the following controls is performed: the floating on time, which is the time during which air is blown by the floating section for each sheet transported to the transport section, is set to a value that suppresses disturbance of the behavior of the sheet during floating. the conveying unit conveys the sheet by suction with air,
10. The sheet supplying device according to claim 7, wherein the control unit, in the low remaining amount mode control, sets a suction wind speed of the conveying unit to a value that suppresses suction of a sheet that is not floating.