JP7443112B2 - sheet feeding device - Google Patents

Description

The present invention relates to a sheet feeding device that feeds sheets.

As a sheet feeding device that supplies sheets, air is blown onto the paper stacked on the paper feed tray to make the paper float, and the highest (top) paper among the floated papers is sucked and conveyed by the suction conveyance means. A paper feeding device that feeds paper to a paper feeding destination is known.

In such a paper feeding device, an optical sensor is used to obtain the amount of light received (sensor value) due to reflected light from the floating paper once for each sheet of paper fed, and if the obtained sensor value is less than a threshold value. , control is performed to raise the paper feed table (see Patent Document 1). As a result, the paper feed table is raised as the number of sheets on the paper feed table decreases due to paper feeding, and the paper on the paper feed table is maintained at a height position appropriate for paper feeding.

Here, if the height position of the paper feed table does not change, as the paper on the paper feed table decreases due to paper feeding, the number of sheets that can float due to air blowing from the air outlet decreases, so the sensor's field of view The amount of paper present within the sensor decreases, and the sensor value obtained decreases. Therefore, as described above, when the acquired sensor value becomes less than the threshold value, the paper feed tray is raised to maintain the paper on the paper feed tray at a height position appropriate for paper feeding.

JP 2019-11150 Publication

By the way, in the above-described paper feeding device, uneven floating of the paper may occur when the paper is floated due to deterioration of alignment of the paper on the paper feeding table due to air blowing. In controlling the height position of the paper feed tray according to the decrease in the number of sheets described above, noise may occur in the sensor value due to uneven floating of the sheet. Due to the influence of this noise, the accuracy of controlling the height position of the paper feed tray may be reduced, and paper feeding problems such as double feeding or blank feeding of paper may occur.

The present invention has been made in view of the above, and an object of the present invention is to provide a sheet feeding device that can reduce sheet feeding problems.

According to one aspect of the present invention, there is provided a loading platform on which sheets are loaded, a drive unit that raises and lowers the loading platform, a floating unit that blows air to the sheets on the loading platform to float the sheets, and a floating unit that blows air onto the sheets on the loading platform to float the sheets. a transport unit that transports the uppermost sheet among the sheets floated by the stacking unit; a light emitting unit that emits light from the side of the sheet on the stacking platform to the sheet side; and a light emitting unit that receives light from the sheet side. a detection unit having a light receiving unit; and a detection unit configured to control the floating unit to stop blowing air during a stop period set for each conveyance cycle of the sheet by the conveyance unit, and to control the sheet to be conveyed to the conveyance unit during the stop period. A control unit that acquires the amount of light received by the light receiving unit at a timing when a sheet other than the sheet levitated by the floating unit is falling, and controls the drive unit based on the acquired amount of light received. A sheet feeding device is provided.

According to another aspect of the present invention, there is provided a loading platform on which sheets are loaded, a drive unit that raises and lowers the loading platform, a floating unit that blows air onto the sheets on the loading platform to float the sheets, and a floating unit that blows air onto the sheets on the loading platform to float the sheets. A conveyance unit that conveys the uppermost sheet among the sheets floated by the floating unit, a light emitting unit that emits light from the side of the sheet on the stacking table to the sheet side, and a light receiving unit that receives light from the sheet side. a detecting unit having a light receiving unit that controls the air blowing by the floating unit during a stop period set for each sheet transport cycle by the transport unit, and controlling the amount of light received by the light receiving unit during the stop period; and a control section that controls the driving section based on an average value of the amount of light received during the most recent plurality of stop periods.

According to another aspect of the present invention, there is provided a loading platform on which sheets are loaded, a drive unit that raises and lowers the loading platform, a floating unit that blows air onto the sheets on the loading platform to float the sheets, and a floating unit that blows air onto the sheets on the loading platform to float the sheets. A conveyance unit that conveys the uppermost sheet among the sheets floated by the floating unit, a light emitting unit that emits light from the side of the sheet on the stacking table to the sheet side, and a light receiving unit that receives light from the sheet side. a detecting section having a light receiving section for detecting the light receiving section; There is provided a sheet feeding device characterized by comprising: a control section that controls the drive section based on an average value of the amount of light received by the section.

According to the sheet feeding device of the present invention, problems in sheet feeding can be reduced.

FIG. 1 is a schematic configuration diagram of a paper feeding device according to a first embodiment. 2 is a control block diagram of the paper feeding device shown in FIG. 1. FIG. 2 is a partially enlarged plan view of the paper feeding device shown in FIG. 1. FIG. FIG. 2 is an enlarged view of the vicinity of the main floating air outlet of the paper feeding device shown in FIG. 1. FIG. FIG. 2 is a partially enlarged view of a side fence of the paper feeding device shown in FIG. 1. FIG. FIG. 3 is a diagram showing a floating state of paper. It is a figure showing sensor value acquisition timing in a 1st embodiment. It is a flow chart for explaining upper limit follow-up control in a 1st embodiment. It is a flow chart for explaining upper limit follow-up control in a 2nd embodiment. It is a figure showing an example of transition of a sensor value. 11 is a diagram showing a moving average value calculated from the sensor values in FIG. 10. FIG. It is a flowchart for explaining upper limit follow-up control in a 3rd embodiment. It is a figure which shows the sensor value acquisition timing in 3rd Embodiment. 11 is a diagram showing a cycle average value calculated from the sensor values in FIG. 10. FIG. It is an explanatory diagram of a measurement exclusion period. FIG. 7 is a diagram illustrating an example of a cycle average value when a measurement exclusion period is provided and when a measurement exclusion period is not provided.

Embodiments of the present invention will be described below with reference to the drawings. The same or equivalent parts and components are designated by the same or equivalent symbols throughout the drawings.

The embodiments shown below exemplify devices etc. for embodying the technical idea of this invention, and the technical idea of this invention includes the material, shape, structure, arrangement etc. of each component. shall not be specified as: 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 configuration diagram of a paper feeding device according to a first embodiment of the present invention. FIG. 2 is a control block diagram of the paper feeding device shown in FIG. 1. 3 is a partially enlarged plan view of the paper feeding device shown in FIG. 1. FIG. FIG. 4 is an enlarged view of the vicinity of the main floating air outlet of the paper feeding device shown in FIG. FIG. 5 is a partially enlarged view of the side fence of the paper feeding device shown in FIG. In the following description, the direction perpendicular to the paper surface of FIG. 1 will be referred to as the front-rear direction, and the front direction of the paper surface will be referred to as the front direction. Moreover, the top, bottom, left and right of the paper surface in FIG. 1 are defined as the top, bottom, left and right directions.

As shown in FIGS. 1 to 3, a paper feeding device (corresponding to a sheet feeding device) 1 according to the first embodiment includes a paper feeding table (corresponding to a loading table) 2, and a lifting motor (corresponding to a driving section) 3. , a paper feed guide plate 4, a sabaki gate 5, two side fences 6, an end fence 7, a floating section 8, a separation section 9, a conveyance section 10, an upper limit sensor (corresponding to a detection section) 11, and , and a control unit 12.

The paper feeding device 1 is a device that feeds paper (equivalent to a sheet) P to a printing section (not shown) of a printing device. The direction from left to right in FIG. 1 is the direction in which the paper P is transported by the transport section 10 during the paper feeding operation. Upstream and downstream in the following description refer to upstream and downstream in the direction in which the paper P is conveyed by the conveying section 10.

The paper feed tray 2 is used to stack paper P used for printing. The paper feed tray 2 is configured to be movable up and down.

A fence insertion hole 2a is formed in the paper feed table 2, into which a side fence 6 to which a side floating mechanism section 22 and a side separation mechanism section 42, which will be described later, are attached, is inserted. Two fence insertion holes 2a are formed corresponding to the two side fences 6, respectively. One fence insertion hole 2a is formed at the front end of the paper feed tray 2, and the other fence insertion hole 2a is formed at the rear end of the paper feed tray 2.

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

The paper feed guide plate 4 is a member that regulates the position of the downstream end (right end) of the paper P on the paper feed table 2 . The paper feed guide plate 4 is disposed near the downstream side of the paper feed table 2 and below the downstream end of a belt unit 51, which will be described later. The upper end of the paper feed guide plate 4 is inclined so that it becomes higher toward the downstream side.

As shown in FIGS. 3 and 4, the paper feed guide plate 4 has a notch 4a in the center in the front-rear direction for blowing air from the main flotation mechanism section 21 (to be described later) onto the paper P on the paper feed table 2. It is formed by cutting out the top of the section.

The sabaki gate 5 is a member that dams up sheets P other than the uppermost sheet P attracted to the transport section 10 among the sheets P floated by the floating section 8 . Two Sabaki gates 5 are installed in the lower vicinity of the downstream end of the conveyance section 10, spaced apart from each other in the front-back direction.

The side fence 6 is a member that restricts the position of the paper P on the paper feed table 2 in the front-rear direction. The two side fences 6 are spaced apart from each other in the front-rear direction. As shown in FIG. 5, the side fence 6 is formed with a side floating air outlet 16 and a side separation air outlet 17. Further, as shown in FIGS. 3 to 5, the side fence 6 is provided with a flow regulating member 18. Note that FIG. 5 is a diagram of the rear side fence 6 viewed from the front side.

The side floating air outlet 16 is an outlet for a side floating air flow generated by a side floating mechanism section 22, which will be described later. The side separation air outlet 17 is an outlet for a side separation airflow generated by a side separation mechanism section 42, which will be described later.

The rectifying member 18 pulls the uppermost sheet P of the sheets P floated by the floating unit 8 on the sheet feed tray 2, and creates a gap between the uppermost sheet P and the second sheet P from the top. This is a member that allows the side separation airflow to flow. The flow regulating member 18 is attached along the upper edge of the side separation air outlet 17 on the inside surface of the side fence 6 (on the paper feed table 2 side). The rectifying member 18 is inclined so as to become higher toward the center of the paper feed tray 2 in the front-rear direction.

The end fence 7 is a member that regulates the position of the upstream end (left end) of the paper P on the paper feed table 2 . The end fence 7 is arranged above the paper feed table 2. The end fence 7 is configured to be movable in the left and right direction.

The floating unit 8 blows air onto the paper P on the paper feed tray 2 to float the paper P. The floating section 8 includes a main floating mechanism section 21 and two side floating mechanism sections 22.

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

The main floating fan 26 blows air onto the paper P on the paper feed table 2 from the downstream side to generate a main floating airflow for floating the paper P.

The shutter 27 switches on and off the main floating air flow from the main floating air outlet 28 . While the main flotation fan 26 is being driven, when the shutter 27 is open, the main flotation airflow is blown out from the main flotation air outlet 28, and when the shutter 27 is closed, the main flotation airflow is blown out from the main flotation air outlet 28. The blowing of the main floating airflow is stopped.

The main floating air outlet 28 is an outlet for a main floating air flow generated by driving the main floating fan 26 . The two main floating air outlets 28 are arranged at a distance from each other in the front-rear direction in the lower vicinity of the downstream end of the conveying section 10.

The two side floating mechanisms 22 are arranged so as to be spaced apart from each other in the front-rear direction with the paper feed table 2 in between. The two side floating mechanisms 22 are installed one each on the outside of the two side fences 6.

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

The side floating fan 31 blows air onto the paper P on the paper feed table 2 from the side floating air outlet 16 of the side fence 6 to generate a side floating airflow for floating the paper P.

The shutter 32 switches on/off the blowing of the side floating airflow from the side floating air outlet 16. While the side floating fan 31 is being driven, when the shutter 32 is open, side floating air flows out from the side floating air outlet 16, and when the shutter 32 is closed, the side floating airflow blows out from the side floating air outlet 16. Blowout of the side floating airflow is stopped.

The separating section 9 separates the uppermost sheet P of the sheets P floated by the floating section 8 from the second and subsequent sheets P from the top. The separation section 9 includes a main separation mechanism section 41 and two side separation mechanism sections 42.

The main separation mechanism section 41 flows air from the downstream side between the uppermost sheet P floated by the floating section 8 and adsorbed to the transport section 10 and the second sheet P from the top. The main separation mechanism section 41 includes a main separation fan 46 and two main separation air outlets 47 .

The main separation fan 46 flows air from the downstream side between the top sheet P and the second sheet P from the top that have been attracted to the conveyance unit 10, and separates the top sheet P and the second sheet from the top. A main separation airflow for separating the paper P is generated.

The main separation air outlet 47 is an outlet for the main floating air flow generated by driving the main separation fan 46. The two main separation air outlets 47 are arranged in the lower vicinity of the downstream end of the conveying section 10 and spaced apart from each other in the front-rear direction. The main separation air outlet 47 blows air upward toward the conveying section 10.

The two side separation mechanisms 42 are arranged so as to be spaced apart from each other in the front-rear direction with the paper feed table 2 in between. The two side separation mechanisms 42 are installed one each on the outside of the two side fences 6. The side separation mechanism section 42 is arranged adjacent to the right side of the side floating mechanism section 22.

The side separation mechanism section 42 draws the top sheet P of the sheets P floated by the floating section 8 toward the rectifying member 18, and separates the top sheet P from the second sheet P from the top. A side separation airflow for this purpose is blown out from a side separation air outlet 17 of the side fence 6. The side separation mechanism section 42 includes a side separation fan 48 that generates side separation airflow.

The conveyance section 10 suctions and conveys the uppermost sheet P of the sheets P floated by the floating section 8 by air suction. The conveyance section 10 includes two belt units 51, a conveyance 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 in parallel in the front-rear direction. The belt unit 51 is disposed straddling the right end of the paper feed tray 2 in the left-right direction. The belt unit 51 includes a conveyor belt 56, a drive roller 57, and a driven roller 58.

The conveyance belt 56 is an annular belt that is stretched around a drive roller 57 and a driven roller 58. A plurality of belt holes 56a are formed in the conveyor belt 56 over the entire circumference. The conveyance belt 56 attracts and holds the paper P on the conveyance surface 56b, which is the lower surface of the conveyance belt 56, by the suction force generated in the belt hole 56a by the drive of the suction fan 54. The paper P is transported by the drive roller 57 driving the transport belt 56 to rotate (endless movement) while holding the paper P by suction.

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 as a result of the rotating conveyor belt 56 . The driven rollers 58 of the two belt units 51 are connected to each other by a shaft 60.

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

The chamber 53 forms a negative pressure chamber for generating suction force in the belt hole 56a of the belt unit 51. The chamber 53 holds the belt unit 51 therein so that the conveying surface 56b of the conveying belt 56 is exposed. A ventilation hole (not shown) is formed in a portion of the bottom plate of the chamber 53 through which the conveyor belt 56 passes. By suctioning air into the chamber 53 through the belt hole 56a of the conveyance surface 56b of the conveyor belt 56 and the ventilation hole of the chamber 53, a suction force is generated in the belt hole 56a.

A 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 hole 56a of the conveyance surface 56b of the conveyance belt 56 and the ventilation hole of the chamber 53. The suction fan 54 is arranged above the chamber 53.

The upper limit sensor 11 monitors the downstream (right side) end surface of the paper P stacked on the paper feed table 2 . The upper limit sensor 11 is disposed at a predetermined height position on the downstream side of the paper feed tray 2 so as to be able to detect floating paper P in a floating area F, which will be described later. The upper limit of the field of view (detection range) of the upper limit sensor 11 is located lower than the upper limit of the floating region F, and the lower limit of the field of view of the upper limit sensor 11 is located higher than the lower limit of the floating region F. The upper limit sensor 11 is a reflective optical sensor and includes a light emitting section 61 and a light receiving section 62.

The light emitting unit 61 emits light from the right side of the paper P on the paper feed table 2 to the left side (paper P side). The light receiving section 62 receives light from the left side (paper P side).

The control unit 12 controls the entire operation of the paper feeding device 1 . The control unit 12 includes a CPU, RAM, ROM, hard disk, and the like.

The control unit 12 floats the paper P on the paper feed table 2 by driving the floating unit 8 and the separating unit 9, causes the uppermost paper P to be attracted to the transport surface 56b, and transports the paper P by the transport unit 10 to the paper feed destination. control to feed paper to At this time, in order to separate the uppermost sheet P from the second or lower sheets P from the top, the control section 12 controls the floating section 8 to blow air onto the sheet P while the conveyance section 10 is transporting the sheet 1. Control on/off for each sheet. That is, as will be described later, the control unit 12 controls the floating unit 8 to stop blowing air during a floating airflow stop period (corresponding to a stopping period) set for each transport cycle of the paper P by the transport unit 10. .

Further, the control unit 12 performs upper limit follow-up control to raise the paper feed tray 2 in response to a decrease in the remaining amount of paper P on the paper feed tray 2 due to paper feeding. As will be described later, in the upper limit follow-up control, the control unit 12 acquires the amount of light received by the light receiving unit 62 (sensor value) at a predetermined sensor value acquisition timing during the floating airflow stop period, and controls the vertical motor based on the acquired sensor value. Control 3.

Next, the operation of the paper feeding device 1 will be explained.

When instructed to start feeding, the control section 12 first performs an initial positioning operation. The initial positioning operation is an operation to adjust the height position of the uppermost sheet P (the top surface of the sheet bundle) on the sheet feeding tray 2 to the upper limit position, which is an appropriate position for sheet feeding.

Specifically, first, the control unit 12 controls the lifting motor 3 to start raising the paper feed tray 2. Here, at the start of the initial positioning operation, the paper feed tray 2 is at a height position such that the stack of sheets on the paper feed tray 2 is not within the field of view (detection range) of the upper limit sensor 11 .

After the paper feed tray 2 starts to rise, when the upper end of the paper stack on the paper feed tray 2 enters the field of view of the upper limit sensor 11, the light reflected by the right end surface of the upper end of the paper stack is received by the light receiving section 62. start. Thereafter, as the paper feed tray 2 rises, the range within the field of view of the upper limit sensor 11 in the stack of sheets on the paper feed tray 2 expands, so that the sensor value at the upper limit sensor 11 increases.

Then, when the sensor value of the upper limit sensor 11 reaches a predetermined non-floating threshold, the control unit 12 stops the sheet feeding table 2 from rising.

Here, the non-floating threshold is defined as the height of the light receiving unit 62 when the height position of the uppermost sheet P (top surface of the sheet stack) on the sheet feed table 2 is at a predetermined sensor position within the field of view of the upper limit sensor 11. This is set as the amount of light received (sensor value). Therefore, by stopping the raising of the paper feed tray 2 when the sensor value reaches the non-floating threshold as described above, the paper feed tray 2 is stops. Thereafter, the control unit 12 adjusts the height position of the uppermost sheet P on the paper feed table 2 to the upper limit position. Specifically, the control unit 12 controls the position between the upper limit position according to the paper type (paper thickness) and the sensor position based on the number of output pulses of an encoder (not shown) connected to the lifting motor 3. The paper feed table 2 is moved by a distance of . This completes the initial positioning operation.

When the initial positioning operation is completed, the control unit 12 starts the paper feeding operation. Specifically, the control unit 12 starts driving the main floating fan 26, the two side floating fans 31, the main separation fan 46, the two side separation fans 48, and the suction fan 54. Both the shutter 27 and the two shutters 32 are in an 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 separation airflow is blown out from the main separation air outlet 47, and a side separation airflow is blown out from the side separation air outlet 17. Further, an attractive force is generated in the belt hole 56a of the belt unit 51.

As shown in FIG. 6, the main floating air current and the side floating air current cause the topmost sheets of paper P in the floating area F to float among the sheets P on the paper feed table 2. Then, the uppermost sheet P of the floating sheets P is attracted to the conveyance surface 56b of the belt unit 51. The floating area F is an area where the floating section 8 floats the sheet P in the vertical direction.

Here, when the paper P floats, in the vicinity of the side fence 6, the side separation airflow blown out from the side separation air outlet 17 flows along the rectification member 18, so that the rectification member 18 and the uppermost sheet P There is a negative pressure between the two. As a result, the uppermost sheet P is drawn toward the rectifying member 18 and comes into contact with the rectifying member 18 . As a result, a side separation airflow flows between the uppermost sheet P and the second sheet P from the top.

On the other hand, on the main separation mechanism section 41 side, after the uppermost sheet P is attracted to the conveyance surface 56b, the main separation airflow blown out from the main separation air outlet 47 transfers the uppermost sheet P attracted to the conveyance surface 56b. Flows toward the upstream side (left side) along.

As a result, between the topmost paper P and the second paper P from the top, the main separation airflow, the side separation airflow from the front side, and the side separation airflow from the rear side collide, and positive pressure is generated. .

In this state, the control unit 12 controls the shutters 27 and 32 to close. Thereafter, the control unit 12 controls the conveyance motor 52 to start driving the belt unit 51.

When the belt unit 51 starts driving, the uppermost sheet P attracted to the transport surface 56b starts to be transported rightward.

In addition, by closing the shutters 27 and 32, the main floating airflow from the main floating air outlet 28 and the side floating airflow from the side floating air outlet 16 are blown out to the paper P on the paper feed tray 2. The speech bubble is stopped. That is, the blowing of air onto the paper P on the paper feed table 2 by the floating section 8 is turned off (stopped). As a result, the positive pressure between the topmost sheet of paper P and the second sheet of paper P from the top pushes down the second and subsequent sheets of paper P from the top, so that the topmost sheet of paper P and the second sheet from the top The following paper P is separated.

As described above, while the uppermost sheet P is conveyed by the belt unit 51, the second and subsequent sheets of paper P from the top fall.

Next, the control section 12 stops the belt unit 51 at a predetermined timing after the belt unit 51 starts driving. After that, the control unit 12 opens the shutters 27 and 32 to levitate the paper P in order to feed the next paper P.

By repeating the above operations, the sheets P are sequentially fed from the sheet feeding device 1 to the sheet feeding destination.

Here, as shown in FIG. 7, the shutters 27 and 32 are periodically closed every time the paper P is transported by the transport section 10 (for each sheet of paper transported by the transport section 10). In other words, the floating airflow stop period, which is a period in which the blowing of air by the floating section 8 to the paper P on the paper feed tray 2 is turned off (stopped) due to the closure of the shutters 27 and 32, occurs every transport cycle of the paper P. is set to .

During the floating airflow stop period, after the uppermost sheet P of the sheets P floated by the main floating airflow and the side floating airflow is attracted to the conveying surface 56b, the main floating airflow and the side floating airflow are stopped to feed the next sheet P. This is the period until the side floating airflow starts blowing. The length of the floating air flow stop period is set according to the size of the paper P (length in the transport direction) and the paper interval, which is the interval between the continuously fed papers P. The length of the conveyance cycle of the paper P depends on the length of the floating airflow stop period.

During the paper feeding operation as described above, the control unit 12 performs the above-described upper limit follow-up control of the paper feeding tray 2. This upper limit follow-up control will be explained with reference to the flowchart of FIG. 8. The process of the flowchart in FIG. 8 starts when the paper feeding operation starts.

In step S1 of FIG. 8, the control unit 12 closes the shutters 27 and 32 at the start of the floating airflow stop period.

Next, in step S2, the control unit 12 determines whether the paper P transported by the transport unit 10 during the current floating airflow stop period is the last paper P to be fed in the current paper feeding operation. .

If it is determined that it is not the last sheet P (step S2: NO), in step S3, the control unit 12 determines whether the sensor value acquisition timing shown in FIG. 7 has arrived. If it is determined that the sensor value acquisition timing has not come (step S3: NO), the control unit 12 repeats step S3.

Here, the sensor value acquisition timing is set as the timing when the sheets P floated by the floating section 8 other than the top sheet P conveyed to the conveying section 10 are falling during the floating airflow stop period. be.

The paper P begins to fall a little after the shutters 27 and 32 are closed (the start of the floating air flow stop period). The sensor value acquisition timing is set after the time when the paper P starts to fall. The sensor value acquisition timing is set in advance based on experiments and the like.

The timing at which the paper P starts to fall differs depending on the paper type, such as thick paper or thin paper, and the paper size. Therefore, the sensor value acquisition timing is set to a timing that corresponds to the combination of paper type and paper size.

If it is determined that the sensor value acquisition timing has come (step S3: YES), the control unit 12 acquires the sensor value at the sensor value acquisition timing from the upper limit sensor 11 in step S4.

Here, the sensor value while the paper P is floating is the amount of light reflected from the end surface of the floating paper P within the field of view (detection range) of the upper limit sensor 11 . Therefore, the sensor value while the paper P is floating increases as the number of floating papers P within the field of view of the upper limit sensor 11 increases.

Further, the number of sheets P that can be floated by blowing air by the floating unit 8 is the number of sheets P that are within the floating area F. Therefore, when the paper P on the paper feed tray 2 is not floating, the lower the height position of the uppermost paper P on the paper feed tray 2 (the top surface of the paper bundle), the more air is blown by the floating section 8. The number of floating sheets of paper P is small.

From this, the sensor value while the paper P is floating can be simulated based on the assumption that the paper P on the paper feed tray 2 is not floating. It can be used as top surface position information indicating the height position of the top surface). If the height position of the paper feed table 2 does not change, as paper feeding progresses, the number of floating papers P decreases, and the sensor value tends to decrease.

Therefore, the paper feeding device 1 acquires sensor values to be used as top surface position information in step S4 described above.

The reason why the sensor value acquisition timing is set to the timing when the paper P is falling is that while the paper P is falling, the sensor value is less susceptible to noise due to uneven floating of the paper P.

Here, in the paper feeding device 1, the floating state of the paper P changes with regularity according to the opening and closing operations of the shutters 27 and 32. Accordingly, the sensor value of the upper limit sensor 11 also changes with regularity.

However, for example, by blowing air onto the paper P on the paper feed tray 2 and causing it to float, the paper alignment on the paper feed tray 2 may deteriorate, resulting in uneven floating, such as a plurality of sheets of paper P floating together. There is. Then, due to uneven floating of the paper P, for example, a large number of paper P temporarily exists within the field of view of the upper limit sensor 11, and noise as shown in FIG. 7 may occur in the sensor values. Obtaining the noise value may reduce the accuracy of upper limit tracking control.

On the other hand, while the paper P is falling, the behavior of the paper P is stable and noise in the sensor values is less likely to occur. Therefore, the sensor value acquisition timing is set to the timing when the paper P is falling.

Returning to FIG. 8, in step S5, the control unit 12 opens the shutters 27 and 32 at the end of the floating airflow stop period.

Next, in step S6, the control unit 12 determines whether the sensor value acquired in step S4 is less than a predetermined floating threshold. The floating threshold is preset as a sensor value threshold at the sensor value acquisition timing for determining whether or not to raise the paper feed tray 2. The floating threshold value is set in advance for each paper type based on experiments and the like.

If it is determined that the sensor value is equal to or greater than the floating threshold (step S6: NO), the control unit 12 returns to step S1 and closes the shutters 27 and 32 at the start of the next floating airflow stop period.

If it is determined that the sensor value is less than the levitation threshold (step S6: YES), in step S7, the control unit 12 determines the starting point of the levitation airflow stop period following the levitation airflow stop period for which the sensor value was acquired in step S4. The shutters 27 and 32 are closed.

Next, in step S8, the control unit 12 controls the lift motor 3 to start raising the paper feed tray 2.

Specifically, the control unit 12 starts raising the paper feed tray 2 by driving the lift motor 3 in the floating airflow stop period following the floating airflow stop period for which the sensor value was acquired in step S4. The raising of the paper feed tray 2 may be started simultaneously with the closing of the shutters 27 and 32 in step S7.

Thereafter, the control unit 12 drives the lifting motor 3 for a predetermined driving time to raise the paper feed tray 2. At this time, the control unit 12 controls the drive voltage of the lifting motor 3 according to the difference between the sensor value acquired in step S4 and the floating threshold.

Specifically, the control unit 12 increases the drive voltage of the lifting motor 3 to increase the amount of rise of the paper feed tray 2 as the difference between the sensor value and the floating threshold increases. The larger the difference between the sensor value and the floating threshold, the fewer the sheets P in the floating area F, and the higher the number of sheets P on the sheet feeding table 2 when the sheet P on the sheet feeding table 2 is not floating. The height position (top surface of the paper stack) is low. Therefore, the control unit 12 performs control such that the larger the difference between the sensor value and the floating threshold, the larger the amount of rise of the paper feed table 2 becomes. The relationship between the difference between the sensor value and the floating threshold and the drive voltage of the lifting motor 3 is set in advance for each paper type based on experiments and the like.

After step S8, the control unit 12 returns to step S2.

Note that the timing at which the lifting motor 3 ends and the lifting of the sheet feeding table 2 stops may be later than the sensor value acquisition timing during the floating airflow stop period when the lifting of the sheet feeding table 2 starts in step S8. .

Further, the drive control of the elevating motor 3 may be performed so that the raising of the paper feed tray 2 is completed during the period when the floating airflow is stopped.

In step S2, if it is determined that it is the last sheet P (step S2: YES), the control unit 12 ends the upper limit follow-up control.

The upper limit follow-up control described above ensures that the height position of the uppermost sheet P (the top surface of the paper stack) on the paper feed tray 2 is appropriate for paper feeding when the paper P on the paper feed tray 2 is not floating. It is maintained at the upper limit position.

As described above, in the paper feeding device 1, the control unit 12 uses the sensor value of the upper limit sensor 11 used in the upper limit follow-up control to control the sensor value of the upper limit sensor 11 used in the upper limit follow-up control to The sensor value is acquired at the sensor value acquisition timing set as the timing when the paper P floated by the floating section 8 is falling. This makes it less susceptible to noise in the sensor value due to uneven floating of the paper P, so the accuracy of upper limit follow-up control can be improved. As a result, it is possible to reduce paper feeding problems such as double feeding caused by too many floating sheets P and empty feeding caused by too few floating sheets P.

Furthermore, when raising the paper feed tray 2 in the upper limit follow-up control, the control unit 12 controls the lift motor 3 to start raising the paper feed tray 2 during the floating airflow stop period.

Here, when the paper feed tray 2 rises while the shutters 27 and 32 are open, the paper P that newly enters the floating area F and floats due to the rise of the paper feed tray 2 is different from the floating paper P. This may affect the behavior and cause uneven floating of the paper P. This floating unevenness may generate noise in the sensor values and may also affect the sensor values at the sensor value acquisition timing. As a result, there is a possibility that the accuracy of the upper limit follow-up control will decrease.

On the other hand, by starting the rise of the paper feed tray 2 during the period when the floating airflow is stopped, it is possible to reduce the situation in which the paper feed tray 2 rises during the period when the shutters 27 and 32 are open. As a result, it is possible to reduce the occurrence of uneven floating of the paper P due to the above-mentioned factors, thereby suppressing a decrease in the accuracy of the upper limit follow-up control.

[Second embodiment]
Next, a second embodiment will be described in which the upper limit follow-up control of the first embodiment described above is modified.

In the second embodiment, the control unit 12 performs upper limit tracking using a moving average value, which is the average value of the sensor values of the upper limit sensor 11 acquired during the floating airflow stop period for the most recent moving average number of times (to be described later), as upper surface position information. Take control.

Upper limit follow-up control in the second embodiment will be explained with reference to the flowchart of FIG. 9. The process of the flowchart in FIG. 9 starts when the paper feeding operation starts. Note that the paper feeding operation in the second embodiment is the same as that in the first embodiment.

The processing in steps S11 to S15 in FIG. 9 is similar to the processing in steps S1 to S5 in FIG. 8 described above.

In step S16, the control unit 12 determines whether the number of times sensor values have been acquired since the start of the current sheet feeding operation is less than a predetermined moving average number of times. In other words, the control unit 12 determines whether the number of sheets fed from the start of the current sheet feeding operation to the present is less than the moving average number of sheets. The number of moving averages is preset as the number of times sensor values are acquired for the number of sensor values for which the moving average value is calculated. The moving average number of times is multiple times.

If it is determined that the number of sensor value acquisitions is less than the moving average number (step S16: YES), the control unit 12 proceeds to step S17. The processing in steps S17 to S19 is similar to the processing in steps S6 to S8 in FIG. 8 described above.

If it is determined that the number of sensor value acquisitions is equal to or greater than the moving average number of times (step S16: NO), in step S20, the control unit 12 controls the number of sensor values acquired during the floating airflow stop period for the most recent moving average number of times, including this time. Calculate the moving average value, which is the average value of the values.

Next, in step S21, the control unit 12 determines whether the moving average value calculated in step S20 is less than a predetermined moving average threshold. The moving average threshold value is set in advance as a threshold value of the moving average value for determining whether or not to raise the paper feed tray 2. The moving average threshold value is set in advance for each paper type based on experiments and the like.

If it is determined that the moving average value is less than the moving average threshold (step S21: YES), the control unit 12 proceeds to step S18.

If it is determined that the moving average value is greater than or equal to the moving average threshold (step S21: NO), the control unit 12 returns to step S11.

By the process of the flowchart of FIG. 9 as described above, upper limit follow-up control is performed using the moving average value as upper surface position information after the number of sheets equal to the number of moving averages has been fed. At a stage before that, the moving average value cannot be calculated, so upper limit follow-up control similar to the first embodiment is performed.

In the moving average value, as shown in FIG. 10, even if noise occurs at the sensor value acquisition timing, the influence of the noise is alleviated as shown in FIG. 11. In the examples of FIGS. 10 and 11, the number of moving averages is 5, and n is an integer of 5 or more.

As described above, in the second embodiment, the control unit 12 calculates the average value of the sensor values acquired in the floating airflow stop period for the most recent moving average number of times after the acquisition of the sensor values for the number of moving average times. The lifting motor 3 is controlled based on the moving average value. As a result, even if the acquired sensor value contains noise, the influence of the noise can be alleviated, so that it is possible to suppress a decrease in the accuracy of the upper limit follow-up control. As a result, paper feeding problems such as double feeding and blank feeding can be further reduced.

[Third embodiment]
Next, a third embodiment will be described in which the upper limit follow-up control of the first embodiment described above is modified.

In the third embodiment, the control unit 12 performs upper limit tracking using a cycle average value, which is an average value of the sensor values of the upper limit sensor 11 at sensor value acquisition timings for a specified number of acquisitions, which will be described later, for each transport cycle as upper surface position information. Take control.

Upper limit follow-up control in the third embodiment will be explained with reference to the flowchart of FIG. 12. The process of the flowchart in FIG. 12 starts when the paper feeding operation starts. Note that also in the third embodiment, the paper feeding operation is the same as in the first embodiment.

The processing in steps S31 and S32 in FIG. 12 is similar to the processing in steps S1 and S2 in FIG. 8 described above.

In step S33, the control unit 12 starts acquiring the sensor value of the upper limit sensor 11. Specifically, the control unit 12 acquires the sensor value at the first timing of the sensor value acquisition timings set for the specified number of times of acquisition for each transport cycle.

Here, the prescribed number of times of acquisition, which is a plurality of times of acquiring sensor values for each conveyance period, and the sensor value acquisition timing for the prescribed number of times of acquisition are set in advance according to the length of the conveyance period. The sensor value acquisition timings in the third embodiment are set to a plurality of equally spaced timings, for example, as shown in FIG. 13. The first sensor value acquisition timing in the transport cycle may be at the same time as the shutters 27 and 32 are closed.

After acquiring the sensor value at the first sensor value acquisition timing, the control unit 12 sequentially acquires the sensor value at each sensor value acquisition timing for the prescribed number of acquisitions set in advance.

After starting acquisition of sensor values in step S33, in step S34, the control unit 12 opens the shutters 27 and 32 at the end of the floating airflow stop period.

Next, in step S35, the control unit 12 determines whether the acquisition of sensor values for the specified number of acquisitions has been completed. If it is determined that the prescribed number of acquisitions of sensor values has not been completed (step S35: NO), the control unit 12 repeats step S35.

If it is determined that the acquisition of sensor values for the prescribed number of acquisitions has been completed (step S35: YES), in step S36, the control unit 12 uses the average value of the sensor values for the prescribed number of acquisitions acquired in the current conveyance cycle. Calculate a certain cycle average value.

Next, in step S37, the control unit 12 determines whether the cycle average value calculated in step S36 is less than a predetermined cycle average threshold. The cycle average threshold value is preset as a threshold value of the cycle average value for determining whether or not to raise the paper feed tray 2. The cycle average threshold value is set in advance for each paper type based on experiments and the like.

If it is determined that the cycle average value is less than the cycle average threshold (step S37: YES), the control unit 12 proceeds to step S38. The processing in steps S38 and S39 is similar to the processing in steps S7 and S8 in FIG. 8 described above.

If it is determined that the cycle average value is equal to or greater than the cycle average threshold (step S37: NO), the control unit 12 returns to step S31.

Through the process shown in the flowchart of FIG. 12 as described above, upper limit follow-up control is performed using the cycle average value, which is the average value of the sensor values for the specified number of times of acquisition for each transport cycle, as the upper surface position information. By using the period average value as the top surface position information, even if noise occurs in the sensor values as shown in FIG. 13, the influence of the noise on the top surface position information is alleviated.

When the sensor value changes as shown in FIG. 10 described above, the periodic average value becomes as shown in FIG. 14. The sensor values shown as comparison targets in FIG. 14 are the same as those in FIG. 11, and are acquired from the sensor values in FIG. 10 at the sensor value acquisition timing in the first and second embodiments. As shown in FIG. 14, the influence of noise is alleviated in the period average value.

As described above, in the third embodiment, the control unit 12 controls the lifting motor 3 based on the cycle average value, which is the average value of the sensor values at the sensor value acquisition timings for the specified number of acquisitions for each conveyance cycle. . As a result, even if the acquired sensor value contains noise, the influence of the noise can be alleviated, so that it is possible to suppress a decrease in the accuracy of the upper limit follow-up control. As a result, paper feeding problems such as double feeding and blank feeding can be further reduced.

Further, in the third embodiment, compared to the second embodiment, the sensor values of the past conveyance cycles are not used, so the responsiveness is excellent.

As shown in FIG. 15, the period from a predetermined time after the start of the floating airflow stop period to the end of the floating airflow stop period is defined as the measurement exclusion period, and during the period other than the measurement exclusion period in the transport cycle, , sensor values may be acquired a prescribed number of times.

In this case, at the start of the measurement exclusion period, all of the sheets P floated by the floating section 8 other than the topmost sheet P transported to the transport section 10 have fallen below the lower limit of the field of view of the upper limit sensor 11. This is the point when the situation is reached. That is, the start point of the measurement exclusion period is the point in time when it is assumed that the change in the sensor value due to the light reflected from the paper P stops due to the paper P falling. The time from the start of the floating air flow stop period to the start of the measurement exclusion period is set in advance based on experiments or the like, depending on the paper interval, paper type, and paper size of the paper P to be fed. Note that the measurement exclusion period may not exist depending on conditions, such as when the interval between the sheets of paper P to be fed is short.

In the measurement exclusion period, there is no sheet P floating within the field of view of the upper limit sensor 11, so the sensor value is a small value and hardly changes. When sensor values are acquired during such a period, the cycle average value becomes a small value. Therefore, the degree of change in the periodic average value becomes small, and there is a possibility that the accuracy of determining the magnitude relationship with the periodic average threshold value decreases. As a result, there is a possibility that the accuracy of the upper limit follow-up control will decrease.

On the other hand, by providing a measurement exclusion period, it is possible to suppress a decrease in the cycle average value and to suppress a decrease in accuracy of upper limit follow-up control.

FIG. 16 shows examples of cycle average values when a measurement exclusion period is provided and when a measurement exclusion period is not provided. As shown in FIG. 16, by providing a measurement exclusion period, the decrease in the cycle average value is suppressed more than when no measurement exclusion period is provided.

Note that when all of the sheets P floated by the floating section 8 other than the topmost sheet P transported to the transport section 10 have fallen onto the sheet feed tray 2, the sheet feed tray 2 is within the field of view of the upper limit sensor 11. If the upper limit sensor 11 is arranged at a position where the upper paper P can enter, all the paper P floated by the floating unit 8 except the uppermost paper P transported to the transport unit 10 The time point at which the sheet is assumed to fall onto the paper feed table 2 may be set as the start time point of the measurement exclusion period.

[Other embodiments]
As mentioned above, the present invention has been described by the first to third embodiments, but the statements and drawings that form part of this disclosure should not be understood as limiting the present invention. Various alternative embodiments, implementations, and operational techniques will be apparent to those skilled in the art from this disclosure.

In the second embodiment described above, similarly to the first embodiment, the sensor value acquisition timing is set during the falling of sheets P floated by the floating section 8 other than the topmost sheet P transported to the transport section 10. The timing is not limited to this. Even if the sensor value acquisition timing is other than this timing, by using the moving average value of the sensor values acquired during the most recent floating airflow stop periods as the top surface position information, the influence of noise on the sensor values is alleviated. Decrease in accuracy of upper limit tracking control can be suppressed.

In the first to third embodiments described above, in the upper limit follow-up control, the raising of the paper feed tray 2 is started during the period when the floating airflow is stopped. It may also begin to rise.

Even in this case, in the first embodiment, the sensor value is acquired at the sensor value acquisition timing during the falling of the paper P floated by the floating unit 8 other than the uppermost paper P transported to the transport unit 10 during the floating air flow stop period. Since the value is acquired, it becomes less susceptible to noise in the sensor value due to uneven floating of the paper P, and a decrease in accuracy of upper limit follow-up control can be suppressed. Furthermore, in the second embodiment, since the moving average value is used as the upper surface position information, the influence of noise on the sensor value is alleviated, and a decrease in accuracy of upper limit tracking control is suppressed. Further, in the third embodiment, since the periodic average value is used as the upper surface position information, the influence of noise on the sensor value is alleviated, and a decrease in accuracy of the upper limit follow-up control is suppressed.

In the first to third embodiments described above, a paper feeding device that feeds paper has been described, but the present invention is also applicable to a device that feeds sheets other than paper.

Thus, it goes without saying that the present invention includes various embodiments not described here. Therefore, the technical scope of the present invention is determined only by the matters specifying the invention in the claims that are reasonable from the above description.

[Additional notes]
This application discloses the following invention.

(Additional note 1)
A loading platform loaded with sheets,
a drive unit that raises and lowers the loading platform;
a floating unit that blows air for floating the sheet onto the sheet on the loading platform;
a conveying section that conveys the uppermost sheet among the sheets floated by the floating section;
a detection unit having a light emitting unit that emits light from a side of the sheet on the loading table to the sheet side, and a light receiving unit that receives light from the sheet side;
The blowing of air by the flotation unit is controlled to be stopped during a stop period set for each conveyance cycle of the sheet by the conveyance unit, and during the stop period, the flotation unit controls the flotation of sheets other than the sheets to be conveyed to the conveyance unit. A control section that acquires the amount of light received by the light receiving section at a timing when the sheet is falling, and controls the driving section based on the acquired amount of received light.

(Additional note 2)
A loading platform loaded with sheets,
a drive unit that raises and lowers the loading platform;
a floating unit that blows air for floating the sheet onto the sheet on the loading platform;
a conveying section that conveys the uppermost sheet among the sheets floated by the floating section;
a detection unit having a light emitting unit that emits light from a side of the sheet on the loading table to the sheet side, and a light receiving unit that receives light from the sheet side;
The air blowing by the floating unit is controlled to be stopped during a stop period set for each sheet transport cycle by the transport unit, and the amount of light received by the light receiving unit is acquired during the stop period, and the amount of light received by the light receiving unit is acquired during the stop period. A control section that controls the drive section based on an average value of the amount of light received during the stop period.

(Additional note 3)
Additional note, wherein the control unit acquires the amount of light received by the light receiving unit during the stop period when a sheet floated by the floating unit other than the sheet being transported to the transport unit is falling. 2. The sheet feeding device according to 2.

(Additional note 4)
A loading platform loaded with sheets,
a drive unit that raises and lowers the loading platform;
a floating unit that blows air for floating the sheet onto the sheet on the loading platform;
a conveying section that conveys the uppermost sheet among the sheets floated by the floating section;
a detection unit having a light emitting unit that emits light from a side of the sheet on the loading table to the sheet side, and a light receiving unit that receives light from the sheet side;
controlling the blowing of air by the floating unit to be stopped during a stop period set for each sheet conveyance cycle by the conveyance unit, and based on an average value of the amount of light received by the light receiving unit at a plurality of timings for each conveyance cycle; , and a control section that controls the drive section.

(Appendix 5)
The control unit acquires the amount of light received by the light receiving unit at a plurality of timings in a period excluding a period from a predetermined time after the start of the stop period to the end of the stop period for each transport cycle. 4. The sheet feeding device according to appendix 4, wherein the average value is calculated based on the average value.

(Appendix 6)
The sheet feeding device according to any one of appendices 1 to 5, wherein the control unit controls the drive unit to start raising the loading platform during the stop period when raising the loading platform. .

1 Paper feeding device 2 Paper feeding table 3 Lifting motor 4 Paper feeding guide plate 5 Sabaki gate 6 Side fence 7 End fence 8 Floating section 9 Separating section 10 Transport section 11 Upper limit sensor 12 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 Conveyance motor 53 Chamber 54 Suction fan 61 Light emitting section 62 Light receiving section

Claims (6)

A loading platform loaded with sheets,
a drive unit that raises and lowers the loading platform;
a floating unit that blows air for floating the sheet onto the sheet on the loading platform;
a conveying section that conveys the uppermost sheet among the sheets floated by the floating section;
a detection unit having a light emitting unit that emits light from a side of the sheet on the loading table to the sheet side, and a light receiving unit that receives light from the sheet side;
The blowing of air by the flotation unit is controlled to be stopped during a stop period set for each conveyance cycle of the sheet by the conveyance unit, and during the stop period, the flotation unit controls the flotation of sheets other than the sheets to be conveyed to the conveyance unit. A control section that acquires the amount of light received by the light receiving section at a timing when the sheet is falling, and controls the driving section based on the acquired amount of received light. A loading platform loaded with sheets,
a drive unit that raises and lowers the loading platform;
a floating unit that blows air for floating the sheet onto the sheet on the loading platform;
a conveying section that conveys the uppermost sheet among the sheets floated by the floating section;
a detection unit having a light emitting unit that emits light from a side of the sheet on the loading table to the sheet side, and a light receiving unit that receives light from the sheet side;
The air blowing by the floating unit is controlled to be stopped during a stop period set for each sheet transport cycle by the transport unit, and the amount of light received by the light receiving unit is acquired during the stop period, and the amount of light received by the light receiving unit is acquired during the stop period, and A control section that controls the drive section based on an average value of the amount of light received during a stop period. The control unit obtains the amount of light received by the light receiving unit at a timing when a sheet levitated by the floating unit other than the sheet being conveyed to the conveyance unit is falling during the stop period. Item 2. The sheet feeding device according to item 2. A loading platform loaded with sheets,
a drive unit that raises and lowers the loading platform;
a floating unit that blows air for floating the sheet onto the sheet on the loading platform;
a conveying section that conveys the uppermost sheet among the sheets floated by the floating section;
a detection unit having a light emitting unit that emits light from a side of the sheet on the loading table to the sheet side, and a light receiving unit that receives light from the sheet side;
controlling the blowing of air by the floating unit to be stopped during a stop period set for each sheet conveyance cycle by the conveyance unit, and based on the average value of the amount of light received by the light receiving unit at a plurality of timings for each of the conveyance cycles; , and a control section that controls the drive section. The control unit acquires the amount of light received by the light receiving unit at a plurality of timings in a period excluding a period from a predetermined time after the start of the stop period to the end of the stop period for each transport cycle. 5. The sheet feeding apparatus according to claim 4, wherein the average value is calculated by using the average value. 6. The control unit controls the drive unit to start raising the loading platform during the stop period when raising the loading platform. Sheet feeding device.