Sheet conveying device and sheet conveying medium

Abstract

The present invention provides a sheet supply device and a sheet conveyance medium, which can perform control corresponding to a small remaining amount of the sheet and suppress conveyance defects as compared with a device that always performs the same rising control without detecting the height information of the floating sheet. The sheet conveyance device includes a processor that, when detecting that the remaining amount of the sheet lifted and transferred on the tray is small, changes the rising control for raising the sheet from the normal state control to the small amount state control.

Description

Technical Field

[0001] The present invention relates to a sheet conveying device and a sheet conveying medium. Background Art

[0002] Patent Document 1 discloses a sheet supply device. Even when a signal indicating that the uppermost sheet of the lifted sheets is within a reasonable range is output from the paper surface detection mechanism, when the uppermost sheet being conveyed passes through the rear end sheet surface sensor and a signal indicating that the upper surface of the uppermost sheet of the lifted sheets is lower than the reference position for determining the height at which sheet feeding can be performed is output from the rear end sheet surface sensor, the sheet supply device controls the lifting unit to raise the tray.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2010-195588 Summary of the Invention

[0006] [Problems to be Solved by the Invention]

[0007] An object of the present invention is to provide a sheet supply device that can suppress conveyance failures when the remaining amount of sheets is small, as compared with a device that always performs the same upward control without detecting the height information of the lifted sheets.

[0008] [Technical Means for Solving the Problems]

[0009] Technical Solution 1 is a sheet conveying device, which includes a processor that, when detecting that the remaining amount of the sheets lifted and transferred on the tray is small, changes the upward control for raising the sheets from the normal state control to the small amount state control.

[0010] Technical Solution 2 is the sheet conveying device according to Technical Solution 1, wherein when the processor detects that the remaining amount has decreased by a specified amount in the small amount state control, the processor raises the sheets by an amount of the small amount state rise that is more than the amount of rise in the normal state control.

[0011] Technical Solution 3 is the sheet conveying device according to Technical Solution 2, wherein the processor detects the case where the remaining amount is small and the case where the remaining amount has decreased by a specified amount in different ways.

[0012] Technical Solution 4 is the sheet conveying device according to Technical Solution 3, wherein the processor detects the case where the remaining amount has decreased by a specified amount based on the number of sheets removed from the tray after changing to the small amount state control.

[0013] Aspect 5 is the sheet conveying device according to Aspect 4, wherein, in terms of the number of sheets for the detection, when the thickness of the sheet is thin, it is more than when the thickness of the sheet is thick.

[0014] Aspect 6 is the sheet conveying device according to Aspect 3, wherein, in the small quantity state control, the processor detects the situation where the remaining quantity has decreased by a specified amount based on the rising amount of the tray that rises according to the height of the sheet on the tray.

[0015] Aspect 7 is the sheet conveying device according to any one of Aspects 1 to 6, wherein, in the small quantity state control, the processor controls the blowing amount of the air for floating the sheet to raise the sheet.

[0016] Aspect 8 is the sheet conveying device according to any one of Aspects 1 to 6, wherein, in the small quantity state control, the processor controls the rising amount of the tray to raise the sheet.

[0017] Aspect 9 is the sheet conveying device according to Aspect 8, wherein, in the small quantity state control, the rising amount of the tray is more when the thickness of the sheet is thick than when the thickness of the sheet is thin.

[0018] Aspect 10 is the sheet conveying device according to Aspect 8 or Aspect 9, wherein, in the small quantity state control, the rising amount of the tray is more when the width dimension of the sheet is wide than when the width dimension of the sheet is narrow.

[0019] Aspect 11 is the sheet conveying device according to any one of Aspects 8 to 10, wherein, in the small quantity state control, the rising amount of the tray is more when the length dimension of the sheet is long than when the length dimension of the sheet is short.

[0020] Aspect 12 is the sheet conveying device according to Aspect 8, wherein, when the tray rises to a position higher than the reference height by an excess amount, when raising the tray by a small quantity state rising amount that is more than the rising amount in the normal state control, the processor raises the tray by a subtraction amount obtained by subtracting the excess amount from the small quantity state rising amount, and the reference height is for detecting the small quantity before the sheet is taken out from the tray.

[0021] Technical solution 13 is a sheet conveying medium that causes a computer to perform the following processing: when it is detected that the remaining amount of the sheet lifted and transferred on the tray is small, the lifting control for lifting the sheet is changed from normal state control to low amount state control.

[0022] [Advantages of the Invention]

[0023] In technical solution 1, compared with a device that keeps the lifting control the same all the time without detecting the height information of the lifted sheet, it is possible to suppress conveyance failures when the remaining amount of the sheet is small.

[0024] In technical solution 2, compared with the case where the lifting amount of the sheet remains unchanged even when the remaining amount of the sheet is small, it is possible to suppress transfer failures of the sheet.

[0025] In technical solution 3, compared with the case where the tray is lifted only based on the height information of the lifted sheet, it is possible to change the detection accuracy of the remaining amount before and after changing to the low amount state control.

[0026] In technical solution 4, compared with the case where the remaining amount is detected based on the lifting amount of the tray, it is possible to achieve detection corresponding to the remaining number of sheets.

[0027] In technical solution 5, compared with the case where detection is always performed based on a fixed number of sheets, it is possible to achieve detection corresponding to the height of the sheet.

[0028] In technical solution 6, compared with the case where the remaining amount is detected based on the number of sheets carried out, it is possible to simplify the control.

[0029] In technical solution 7, compared with the case of lifting the tray, it is possible to simplify the mechanism for lifting the sheet.

[0030] In technical solution 8, compared with the case of controlling the blowing amount of the air that makes the sheet float, it is possible to facilitate the adjustment of the height of the sheet.

[0031] In technical solution 9, compared with the case where the lifting amount is always fixed regardless of the sheet width, it is possible to achieve the lifting of the tray corresponding to the sheet thickness.

[0032] In technical solution 10, compared with the case where the lifting amount is fixed, it is possible to achieve the lifting of the tray corresponding to the sheet width.

[0033] In technical solution 11, compared with the case where the lifting amount is fixed regardless of the sheet length, it is possible to achieve the lifting of the tray corresponding to the sheet length.

[0034] In Technical Solution 12, compared with the case where the rising amount in the normal state control is fixed, it is possible to achieve the rising of the tray corresponding to the case where the sheet supply amount to the tray is small.

[0035] In Technical Solution 13, compared with the case where the tray is raised only according to the height information of the floating sheet, it is possible to achieve control corresponding to the case where the remaining amount of the sheet is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a perspective view of an image forming apparatus including a sheet conveying device according to the first embodiment.

[0037] Figure 2 It is a perspective view of the inside of a sheet conveying device according to an embodiment.

[0038] Figure 3 It is an enlarged view of the main part of the housing portion.

[0039] Figure 4 It is an explanatory view showing the case of conveying the sheet in the housing portion.

[0040] Figure 5 It is an explanatory view showing a state where the remaining amount of the sheet in the housing portion is large.

[0041] Figure 6 It is a block diagram showing an example of the hardware configuration of a sheet conveying device according to an embodiment.

[0042] Figure 7 It is a flowchart showing an example of a rising process according to an embodiment.

[0043] Figure 8 It is a flowchart showing an example of a small amount state control process according to an embodiment.

[0044] Figure 9 It is a flowchart showing an example of a reduction amount detection process (1) according to an embodiment.

[0045] Figure 10 It is a flowchart showing an example of a reduction amount detection process (2) according to an embodiment.

[0046] Figure 11 It is a flowchart showing an example of a rising amount determination process according to an embodiment.

[0047] Figure 12 It is a flowchart showing an example of a sheet thickness corresponding process according to an embodiment.

[0048] Figure 13 It is a flowchart showing an example of a sheet width corresponding process according to an embodiment.

[0049] Figure 14 It is a flowchart showing an example of sheet length corresponding processing according to an embodiment.

[0050] Figure 15 It is a flowchart showing an example of rising amount adjustment processing according to an embodiment.

[0051] [Explanation of reference numerals]

[0052] 10: Sheet conveying device

[0053] 40: Sheet storage section

[0054] 42: Tray

[0055] 46: Air supply fan

[0056] 54: Floating device

[0057] 56: Small amount detector

[0058] 74: Lifting device

[0059] 86: Small amount sensor

[0060] 96: Reference height

[0061] 100: Sheet height detector

[0062] 110: Conveying device

[0063] 210: CPU

[0064] 214: Storage section

[0065] 214A: Sheet conveying program

[0066] 216: Input section

[0067] 226: Fan drive section

[0068] 228: Recording medium Detailed implementation mode

[0069] Hereinafter, an embodiment will be described with reference to the drawings.

[0070] In the following description, the direction indicated by the arrow X in the drawings is set as the device width direction, and the direction indicated by the arrow Y is set as the device height direction. Moreover, the direction indicated by the arrow Z orthogonal to the device width direction X and the device height direction Y is set as the device depth direction.

[0071] Figure 1FIG. 0 is a perspective view showing an image forming apparatus 14 provided with a sheet feeding device 12 having a sheet conveying device 10 of the present embodiment. The image forming apparatus 14 is an apparatus that forms an image on a sheet P, and includes an image forming member (not shown) that forms an image on the sheet P, and a conveying member (not shown) that conveys the sheet P to the image forming member.

[0072] In a device body 12A of the sheet feeding device 12, an upper storage portion 16 and a lower storage portion 18 for storing the sheet P are provided so as to be withdrawable from the device body 12A. Further, the sheet conveying device 10 of the sheet feeding device 12 is configured to be attachable with an extension portion 22. Figure 1 FIG. 5 shows a state in which the extension portion 22 is attached. The extension portion is an option and extends from one surface 20 on one side HI in the width direction.

[0073] Here, the sheet P can also be referred to as a medium or film for image formation. Examples of the sheet P include paper sheets and overhead projector (OHP) sheets containing polyethylene terephthalate (PET) resin. Examples of the sheet P for image formation include normal sheets supplied from the respective storage portions 16 and 18 and long sheets supplied using the extension portion 22. Further, as the sheet P to be used, various sheets P such as sheets P having different thicknesses, different width dimensions, and different lengths can be used.

[0074] The upper part of the upper storage portion 16 can be opened and closed by a cover 30 supported by the device body 12A and an extension cover 32 supported by the extension portion 22. A damper 34 extending from the device body 12A is connected to the cover 30 to assist the opening and closing operation.

[0075] Figure 2 FIG. 15 is a view showing the sheet conveying device 10 in the sheet feeding device 12, showing a state in which the extension portion 22 is removed from the sheet conveying device 10 and an end bar 36 is erected. In the sheet feeding device 12 having the sheet conveying device 10, a sheet storage portion 40 for storing the sheet P is provided.

[0076] The sheet storage portion 40 includes a tray 42 forming a bottom plate and side walls 44 erected on both side portions of the tray 42. The trailing edge of the sheet P placed on the tray 42 is positioned by the end bar 36, and the side edges are positioned by the both side walls 44.

[0077] (Side wall)

[0078] On the outer surface of each side wall 44, there is provided a blower fan 46 (only one is shown in the figure), and a first duct 48 and a second duct 50 extend from the blower fan 46. The first duct 48 is connected to a blower hole 52 (only one is shown in the figure) formed in the upper part on the image forming device 14 side of the side wall 44, and blows the air sent out from the blower fan 46 from both ribs toward the sheet P placed on the tray 42.

[0079] The blower hole 52 is formed in a vertically long rectangular shape, and blows air on the sheet P in any height range arranged in the upper part among the sheets P stacked on the tray 42 to make it float. Thus, the blower fan 46, the first duct 48, and the blower hole 52 formed in the side wall 44 constitute a floating device 54 for floating the sheet P on the tray 42.

[0080] From the front edge on the image forming device 14 side of each side wall 44, a front edge flange 44A bent toward the side extends, and from the upper edge of each side wall 44, an upper edge flange 44B bent toward the side extends. Moreover, from the rear edge of each side wall 44, a rear edge flange 44C bent toward the side extends, and a sheet amount detector 56 is provided on the rear edge flange 44C of one of the side walls 44.

[0081] (Tray)

[0082] The tray 42 is formed in a rectangular plate shape, and support members 58 (only one is shown in the figure) extending in the width direction are provided on the lower surfaces of the front edge portion on the image forming device 14 side and the rear edge portion on the side away from the image forming device 14. The end portions of the respective support members 58 extend from the tray 42 (only one is shown in the figure), and the front ends of the wire 60 are fixed to the respective end portions.

[0083] The wire 60 extending from the support member 58 provided at the rear edge of the tray 42 is wound around the winding pulley 70 of the lifting portion 68 via a first pulley, a second pulley 64, and a third pulley 66 provided in a frame (not shown). Moreover, the wire 60 extending from the support member provided at the front edge of the tray 42 is wound around the winding pulley 70 of the lifting portion 68 via the third pulley 66. As an example, a height sensor (not shown) for detecting the height position of the tray 42 is provided in the lifting portion 68.

[0084] The winding pulley 70 is detachably connected to the rotation shaft of the drive motor 72 via a clutch, for example. By rotating the winding pulley 70 by using the drive motor 72, the tray 42 suspended by the respective wires 60 is lifted and lowered. Moreover, by operating the clutch to cut off the connection state between the drive motor 72 and the winding pulley 70, the tray 42 suspended by the respective wires 60 can be lowered by its own weight.

[0085] Thus, a lifting device 74 for lifting the tray 42 is constituted by a support member 58 of the tray 42, a wire 60 extending from the support member 58, pulleys 62, 64, 66, 70 for supporting the wire 60, a drive motor 72 for rotating the winding pulley 70, and a clutch.

[0086] At the rear end of the tray 42, an extension 42A extending laterally is formed. The extension 42A moves up and down along the trailing edge flange 44C of each side wall 44 as the tray 42 is lifted or lowered. Moreover, when the tray 42 rises, the extension 42A enables the operation of the small quantity detector 56.

[0087] [Small quantity detector]

[0088] The small quantity detector 56, as Figure 3 shown, includes: a fixed bracket 80 fixed to the side wall 44; and a sliding bracket 82 supported by the fixed bracket 80 so as to be movable up and down. Moreover, the small quantity detector 56 includes: a detection element 84 fixed to the sliding bracket 82; and a small quantity sensor 86 provided on the fixed bracket 80.

[0089] The small quantity sensor 86 includes a sensor for detecting the movement of the sliding bracket 82, and the small quantity sensor 86 includes a photoelectric sensor as an example of the sensor. The small quantity sensor 86 includes a light emitting portion for emitting light and a light receiving portion for detecting the light from the light emitting portion, and a gap is formed between the light emitting portion and the light receiving portion.

[0090] In the fixed bracket 80, long holes 88 extending vertically are formed at two upper and lower positions. In each long hole 88, a shaft 90 extending from the sliding bracket 82 is inserted so as to be movable up and down.

[0091] In the sliding bracket 82, a rectangular protruding piece 92 protruding toward the image forming device 14 is formed. The protruding piece 92 is disposed in the gap of the small quantity sensor 86 in a normal state where the shaft 90 extending from the sliding bracket 82 is supported by the lower edge of the long hole 88 to block the optical path from the light emitting portion of the small quantity sensor 86 to the light receiving portion.

[0092] In the sliding bracket 82, a base portion 84A of the detection element 84 is fixed. The base portion 84A penetrates a rectangular through hole 94 provided in the trailing edge flange 44C of the side wall 44. An upper extension piece 84B extends upward from the front end of the base portion 84A, and a claw portion 84C extends from the upper end of the upper extension piece 84B to the upper portion of the extension 42A of the tray 42.

[0093] The lower surface of the claw portion 84C is formed flat, and when the rising tray 42 reaches a reference height 96 indicating a specified height, it contacts the upper surface of the tray 42 to cause the detection element 84 to rise together with the tray 42.

[0094] When the sliding bracket 82 rises as the detection element 84 rises, the protruding piece 92 of the sliding bracket 82 leaves the optical path of the small amount sensor 86, allowing the light from the light emitting part of the small amount sensor 86 to pass through to the light receiving part. Then, the light receiving part that receives the light from the light emitting part enables operation, and the tray 42 that rises corresponding to the decrease in the remaining amount of the sheet on the tray 42 reaches the reference height 96, and outputs a signal indicating that the remaining amount of the sheet is a small amount.

[0095] (End strip)

[0096] The end strip 36 is arranged on the trailing edge side of the tray 42, and a sheet height detector 100 is provided at the upper end of the end strip 36.

[0097] [Sheet height detector]

[0098] The sheet height detector 100 includes: an arm part 100A, the base end part of which is rotatably supported by the end strip 36; and a roller 100B, which is rotatably supported by the front end part of the arm part 100A. Moreover, the sheet height detector 100 includes a sheet height switch (not shown), and the sheet height switch enables operation by detecting the inclination of the arm part 100A with the base end part as the center. The roller 100B is configured to contact the sheet P placed on the uppermost part of the tray 42 and can rotate in the supply direction of the sheet P.

[0099] When the roller 100B of the sheet height detector 100 contacts the sheet P on the tray 42 and the front end of the arm part 100A tilts upward, the sheet height switch enables operation and outputs a signal indicating that the height position of the sheet P at the uppermost part of the tray 42 is a height suitable for supply. Moreover, when the roller 100B leaves the sheet P and the front end of the arm part 100A tilts downward, the sheet height switch disconnects operation and outputs a signal indicating that the height position of the sheet P at the uppermost part of the tray 42 is lower than the height suitable for supply.

[0100] (Conveying device)

[0101] Above the tray 42, as Figure 4 shown, a conveying device 110 for adsorbing and conveying the floating sheet P is provided on the side of the image forming apparatus 14.

[0102] The conveying device 110 includes: an adsorption head 112 that adsorbs the floating sheet P; and a moving mechanism (not shown) that moves the adsorption head 112 in the device width direction X.

[0103] The adsorption head 112 is, as Figure 5 shown, arranged at the center in the width direction of the tray 42 of the sheet P.

[0104] The suction head 112 has a negative pressure chamber supplied with negative pressure from a negative pressure device (not shown), and a plurality of suction holes leading to the negative pressure chamber are formed on the lower surface of the suction head 112. Thus, the suction head 112 adsorbs and holds the floating sheet P by the negative pressure from the suction holes.

[0105] The moving mechanism, as Figure 4 shown, moves the suction head 112 between the suction position 114 and the delivery position 116.

[0106] The suction position 114 is set at a position where the central portion in the longitudinal direction of the suction head 112 is located at the center in the width direction of the air supply hole 52 (refer to Figure 2 ), making it easier to adsorb the sheet P floated by the floating device 54 (refer to Figure 2 ).

[0107] The delivery position 116 indicates the position when the sheet P adsorbed at the suction position 114 is transported to the image forming device 14 side. At the delivery position 116, the front end portion of the transported sheet P is inserted between the upper and lower delivery rollers 120 provided in the image forming device 14, thereby transferring the sheet P to the image forming device 14.

[0108] (Hardware Structure of Sheet Transport Device)

[0109] The sheet transport device 10, as Figure 6 shown, includes: a central processing unit (CPU) 210 which is a control unit and constitutes a processor, a memory 212 such as a random access memory (RAM) that forms a temporary storage area, a storage unit 214 including a non-volatile read only memory (ROM), an input unit 216, and a display unit 218 including a liquid crystal display. Moreover, the sheet transport device 10 includes: an informing unit 220 including a speaker, a communication interface (I / F) unit 222 for communicating with external devices, a tray driving unit 224 including a lifting device 74, and a fan driving unit 226 for driving the air supply fan 46 of the floating device 54. And the sheet transport device 10 includes a medium reader / writer (R / W) 227 as an example of a device for program input.

[0110] The CPU 210, memory 212, storage unit 214, input unit 216, display unit 218, notification unit 220, communication I / F unit 222, tray drive unit 224, fan drive unit 226, and medium reading / writing device 227 are connected to each other via the bus B1. The medium reading / writing device 227 reads out the information written to the recording medium 228 and writes the information to the recording medium 228.

[0111] Connected to the input unit 216 are a small amount of sensors 86 of the small amount detector 56, an unillustrated sheet height switch of the sheet height detector 100, an operation panel provided on the sheet conveying device 10, and an unillustrated height sensor that detects the height position of the tray. Further, the input unit 216 sends the states of the small amount sensors 86 and the sheet height switch and the input information to the operation panel to the CPU 210.

[0112] On the operation panel, sheet size information indicating the size of the sheet P set on the tray 42, basis weight information of the sheet P, and on / off information of the small amount control are input, and these input information are stored in the RAM.

[0113] Here, the basis weight means the weight per unit area of the sheet P, and the thickness dimension of the sheet P can be judged based on the basis weight.

[0114] The storage unit 214 is implemented by a hard disk drive (HDD), a solid state drive (SSD), a flash memory, or the like. In the recording medium 228 serving as the storage unit, a sheet conveying program 214A for operating the sheet conveying device 10 is stored.

[0115] The sheet conveying program 214A is read out from the recording medium 228 provided in the medium reading / writing device 227 and stored in the storage unit 214. Alternatively, the sheet conveying program 214A can also be downloaded via a network.

[0116] The CPU 210 reads out the sheet conveying program 214A from the storage unit 214 and expands it into the memory 212, and constitutes a processor and a control unit by sequentially executing the processes included in the sheet conveying program 214A. By operating according to the sheet conveying program 214A, the CPU 210 causes the sheet conveying device 10 to operate.

[0117] (Operation description)

[0118] Next, with reference to Figures 7 to 15 the operation of the sheet conveying device of the present embodiment will be described.

[0119] (Ascending Process)

[0120] When the CPU 210 of the sheet conveying device executes the sheet conveying program 214A and calls the ascending process during the conveying control process, as Figure 7 shown, for example, it is determined whether the small quantity control is set to enabled (S1) by input on the operation panel of the sheet conveying device 10.

[0121] In step S1, when the small quantity control is off and the user has selected not to perform the small quantity control, the process returns to the routine that called the ascending process.

[0122] Moreover, in step S1, when the small quantity control is enabled and the user has selected to perform the small quantity control, it is determined from the input unit 216 whether the small quantity sensor 86 of the small quantity detector 56 has been enabled to operate (S2).

[0123] In step S2, when the small quantity sensor 86 has not been enabled to operate and the remaining quantity of the sheet P lifted and transferred on the tray 42 is more than the specified value, ascending control to raise the sheet P is performed by normal control processing (S3), and the process returns to the routine that called the ascending process.

[0124] On the other hand, in step S2, when the tray 42 rises as the remaining quantity of the sheet on the tray 42 decreases, and thus the small quantity sensor 86 is enabled to operate, the remaining quantity of the sheet P lifted and transferred on the tray 42 is small, so the small quantity state control process is executed (S4), and the process returns to the routine that called the ascending process.

[0125] (Small Quantity State Control Process)

[0126] In the small quantity state control process, as Figure 8 shown, the reduction quantity detection process (SB1) is executed.

[0127] (Reduction Quantity Detection Process (1))

[0128] As the reduction quantity detection process, as Figure 9 shown, the reduction quantity detection process (1) is cited as an example. In the reduction quantity detection process (1), it is determined whether the remaining quantity of the sheet P on the tray 42 has decreased by a specified amount (SC1).

[0129] As an example, the determination of whether the remaining quantity has decreased by the specified amount is made using the signal from the sheet height detector 100, and the sheet height detector 100 detects the case where the height position of the sheet P at the top of the tray 42 is lower than the height suitable for supply.

[0130] Thus, the determination of whether the remaining amount has decreased by a specified amount is made in a different manner from the determination by the small amount sensor 86 as to whether the remaining amount is a small amount.

[0131] In the case where the remaining amount has decreased by the specified amount in step SC1, the rising flag preset in the RAM is set to "1", and the process returns to the small amount state control process that called the small amount state control process (1). On the other hand, in the case where the remaining amount has not decreased by the specified amount in step SC1, the rising flag is maintained at "0" and the process returns to the small amount state control process that called the small amount state control process.

[0132] Here, the rising flag is a flag for determining whether to raise the tray 42. When the rising flag is "1", the tray 42 is raised using the small amount state control process. Moreover, when the rising flag is "0", the tray 42 is not raised using the small amount state control process.

[0133] (Reduction amount detection process (2))

[0134] On the other hand, Figure 10 FIG. is a diagram showing a reduction amount detection process (2) as another example of the reduction amount detection process. In the reduction amount detection process (2), based on the number of sheets P unloaded from the tray 42 after changing to the small amount state control, the case where the remaining amount has decreased by a specified amount is detected. Thus, the determination of whether the remaining amount has decreased by the specified amount is made in a different manner from the determination by the small amount sensor 86 as to whether the remaining amount is a small amount.

[0135] The number of sheets P used for the detection varies according to the thickness of the sheet P. Regarding the number of sheets P used for the detection, it is larger when the thickness of the sheet P is thin than when the thickness of the sheet P is thick. That is, in the reduction amount detection process (2), it is determined whether the number of sheets P unloaded from the tray 42 after changing to the small amount state control exceeds the specified amount (SD1) calculated based on the grammage information stored in the RAM.

[0136] In the calculation of the specified amount, the thickness dimension of the sheet P is calculated based on the grammage information, and the specified amount is reduced when the sheet P is thick. Moreover, the specified amount is increased when the sheet P is thin. Thus, it is determined whether the specified amount of sheets P calculated based on the thickness dimension of the sheet P has been unloaded from the tray 42.

[0137] When it is determined in step SD1 that the number of sheets P removed from the tray 42 after changing to the low quantity state control exceeds the specified quantity, set "1" for the rising flag preset in the RAM, and return to the low quantity state control process that called the said low quantity state control process (2). On the other hand, when it is determined in step SD1 that the number of sheets P removed from the tray 42 after changing to the low quantity state control has not exceeded the specified quantity, keep the rising flag as "0" and return to the low quantity state control process that called the said low quantity state control process.

[0138] (Low quantity state control process)

[0139] In the low quantity state control process, determine whether the rising flag is set to "1" (SB2).

[0140] In the said step SB2, when the rising flag is "0", return to the routine that called the said low quantity state control process. On the other hand, when it is determined in step SB2 that the rising flag is "1", execute the rising quantity determination process (SB3).

[0141] (Rising quantity determination process)

[0142] In the rising quantity determination process, as Figure 11 shown, after sequentially executing the sheet thickness corresponding process (SF1), the sheet width corresponding process (SF2), the sheet length corresponding process (SF3) and the rising quantity adjustment process (SF4), return to the low quantity state control process that called the said rising quantity determination process.

[0143] (Sheet thickness corresponding process)

[0144] In the sheet thickness corresponding process, as Figure 12 shown, as an example, compare the grammage information stored in the RAM with a predetermined thick paper threshold value to determine whether the sheet P is thick paper (SG1).

[0145] When it is determined in step SG1 that the sheet is thick paper, increase the preset low quantity rising quantity in the RAM by a preset increase amount (SG2), return to the rising quantity determination process and then execute the sheet width corresponding process (SF2).

[0146] The said low quantity rising quantity represents the rising quantity of the tray 42 used to make the sheet P rise when the remaining quantity of the sheet P in the low quantity state control decreases by a specified quantity. For the low quantity rising quantity, a predetermined low quantity reference quantity is set.

[0147] When it is determined in step SG1 that the sheet is not thick paper, as an example, compare the grammage information stored in the RAM with a predetermined thin paper threshold value to determine whether the sheet P is thin paper (SG3).

[0148] When it is determined in step SG3 that the sheet is not thin paper, the process returns to the lift amount determination process and then the sheet width corresponding process (SF2) is executed. On the other hand, when it is determined in step SG3 that the sheet is thin paper, the small amount state lift amount preset in the RAM is decreased by a preset decrease amount (SG4), and the process returns to the lift amount determination process and then the sheet width corresponding process (SF2) is executed.

[0149] Thus, in the small amount state control, the lift amount of the tray is made larger when the thickness of the sheet is thicker than when the thickness of the sheet is thinner.

[0150] (Sheet width corresponding process)

[0151] When the sheet width corresponding process (SF2) is called from the lift amount determination process, as Figure 13 shown, as an example, the sheet size information stored in the RAM is compared with a predetermined reference width threshold to determine whether the sheet P is a wide sheet (SH1).

[0152] When it is determined in step SH1 that the width of the sheet P is greater than the reference threshold and is a wide sheet, the small amount state lift amount preset in the RAM is increased by a preset increase amount (SH2), and the process returns to the lift amount determination process and then the sheet length corresponding process (SF3) is executed.

[0153] When it is determined in step SH1 that the width of the sheet P is below the reference threshold and is not a wide sheet, as an example, the sheet size information stored in the RAM is compared with a predetermined reference width threshold to determine whether the sheet P is a narrow sheet (SH3).

[0154] When it is determined in step SH3 that it is not a narrow sheet, the process returns to the lift amount determination process and then the sheet length corresponding process (SF3) is executed. On the other hand, when it is determined in step SH3 that it is a narrow sheet, the small amount state lift amount preset in the RAM is decreased by a preset decrease amount (SH4), and the process returns to the lift amount determination process and then the sheet length corresponding process (SF3) is executed.

[0155] Thus, in the small amount state control, the lift amount of the tray 42 is made larger when the width dimension of the sheet P is wider than when the width dimension of the sheet P is narrower.

[0156] (Sheet length corresponding process)

[0157] When the sheet length corresponding process (SF3) is called from the lift amount determination process, as Figure 14 shown, as an example, the sheet size information stored in the RAM is compared with a predetermined reference length threshold to determine whether the sheet P is long (SJ1).

[0158] In step SJ1, when it is determined that the length of the sheet P is greater than the reference length threshold and is long, the small amount state increase amount preset in the RAM is increased by a preset increase amount (SJ2), and after returning to the increase amount determination process, the increase amount adjustment process (SF4) is executed.

[0159] In step SJ1, when it is determined that the length of the sheet P is less than or equal to the reference length threshold and is not long, as an example, the sheet size information stored in the RAM is compared with a predetermined reference length threshold to determine whether the sheet P is short (SJ3).

[0160] In step SJ3, when it is determined that it is not short, it returns to the increase amount determination process. On the other hand, in step SJ3, when it is determined that it is short, the small amount state increase amount preset in the RAM is decreased by a preset decrease amount (SJ4), and it returns to the increase amount determination process.

[0161] Thus, in the small amount state control, the ascending amount of the tray 42 is made larger when the length dimension of the sheet P is long than when the length dimension of the sheet P is short.

[0162] Here, the small amount state reference amount, which is preset as the small amount state increase amount in the RAM, is set to a value larger than the ascending amount in the normal state control. Moreover, in the normal state control, the ascending amount is also increased or decreased according to the sheet thickness, sheet width, and sheet length, and as an example, the decrease amount or increase amount during the increase or decrease is set to the same amount as in the small amount state control.

[0163] Therefore, in the state where the sheet thickness corresponding process (SF1), the sheet width corresponding process (SF2), and the sheet length corresponding process (SF3) have been executed in the increase amount determination process, the value set as the small amount state increase amount becomes larger than the ascending amount in the normal state control.

[0164] Thus, in the small amount state control, it is possible to make the sheet P ascend by a small amount state increase amount that is larger than the ascending amount in the normal state control.

[0165] (Ascending amount adjustment process)

[0166] In the increase amount determination process, the increase amount adjustment process (SF4) is called, and as Figure 15 shown, the increase amount adjustment process is executed.

[0167] The ascending amount adjustment process is a process for raising the tray 42 when the tray 42 ascends to a position higher than the reference height 96, and the reference height 96 is used to detect a small amount before the sheet P is carried out from the tray 42.

[0168] In the rising amount adjustment process, as an example, the height of the tray 42 is compared with the height threshold value pre-stored in the ROM to determine whether the tray 42 is at a position higher than the reference height 96 (SK1).

[0169] Here, the height threshold value stored in the ROM is set to a value representing a position that is a specified amount higher than the reference height 96 at which the sheet height detector 100 is enabled to operate. Thus, even if the tray 42 stops at a position higher than the reference height 96 at which the sheet height detector 100 is enabled to operate, as long as the tray 42 does not stop at a position that is a specified amount higher than the reference height 96, the rising amount adjustment process is not executed.

[0170] In the case where it is determined in step SK1 that the tray 42 is not at a position higher than the height position indicated by the height threshold value, after returning to the rising amount determination process, it returns to the small amount state control process. After the tray 42 is raised by the rising amount set as the small amount state rising amount (SB4), it returns to the rising process.

[0171] Thus, the sheet P on the tray 42 is raised by the rising amount set based on the sheet thickness, sheet width, and sheet length.

[0172] On the other hand, in the case where it is determined in step SK1 that the tray 42 is at a position higher than the height position indicated by the height threshold value, the reference height 96 is subtracted from the current height of the tray 42 as the excess amount (SK2). Next, the excess amount is subtracted from the small amount state rising amount specified in the sheet thickness corresponding process, sheet width corresponding process, and sheet length corresponding process to obtain a subtraction amount (SK3).

[0173] Next, the subtraction amount is set as the small amount state rising amount (SK4). After returning to the rising amount determination process, it returns to the small amount state control process. The tray 42 is raised according to the rising amount set as the small amount state rising amount (SB4), and then it returns to the rising process.

[0174] Thus, in the case where the tray 42 rises to a position higher than the reference height 96 by the excess amount, when the tray 42 is raised by a small amount state rising amount that is more than the rising amount in the normal state control, the tray 42 is raised by the subtraction amount obtained by subtracting the excess amount from the small amount state rising amount.

[0175] Here, in the present embodiment, the case where the sheet P on the tray 42 is raised by raising the tray 42 in the small amount state control has been described, but it is not limited thereto. For example, in the small amount state control, the output of the air supply fan 46 for floating the sheet P can also be increased, and the sheet P can be raised by controlling the air blowing amount.

[0176] (Function and effect)

[0177] The operation of this embodiment of the above structure will be described.

[0178] In this embodiment, when it is detected that the remaining amount of the sheet P lifted and transferred on the tray 42 is small, the lifting control for raising the sheet P is changed from the normal state control to the small amount state control.

[0179] Therefore, compared with a device that always has the same lifting control without detecting the height information of the lifted sheet P, it is possible to achieve control corresponding to the case where the remaining amount of the sheet is small. Thus, conveyance failures can be suppressed.

[0180] Moreover, compared with the case where the tray 42 is lifted only based on the height information of the lifted sheet P, it is possible to achieve control corresponding to the case where the remaining amount of the sheet is small.

[0181] Moreover, when it is detected in the small amount state control that the remaining amount has decreased by a specified amount, the sheet P is lifted by a small amount state lift amount that is more than the lift amount in the normal state control.

[0182] Therefore, compared with the case where the lift amount of the sheet P remains unchanged even when the remaining amount of the sheet P is small, it is possible to suppress transfer failures of the sheet P.

[0183] Specifically, when the remaining amount on the tray 42 becomes small and the floating height of the uppermost sheet P becomes low, the distance from the adsorption surface of the adsorption head 112 to the sheet P will become far. Then, it takes time to adsorb the sheet P, and a miss feed may occur.

[0184] Moreover, when the sheet P is thin-walled, sagging may occur at both side ends. At this time, an unexpected collision may occur in the downstream conveyance path, causing damage to the sheet P or a miss feed.

[0185] In contrast, in this embodiment, when it is detected in the small amount state control that the remaining amount has decreased by a specified amount, the sheet P is lifted by a small amount state lift amount that is more than the lift amount in the normal state control, thereby suppressing possible failures during the transfer of the sheet P.

[0186] Moreover, the case where the remaining amount is small and the case where the remaining amount has decreased by a specified amount are detected in different ways.

[0187] Therefore, compared with the case where the tray 42 is lifted only based on the height information of the lifted sheet P, it is possible to change the detection accuracy of the remaining amount before and after changing to the small amount state control.

[0188] In addition, in the reduction amount detection process (2), based on the number of sheets P carried out from the tray 42 after changing to the small amount state control, the case where the remaining amount has decreased by a specified amount is detected.

[0189] Therefore, compared with the case of detecting the remaining amount based on the rising amount of the tray 42, detection corresponding to the remaining number of sheets can be achieved.

[0190] Moreover, regarding the number of sheets P used for detection, when the thickness of the sheet P is thin, it is more than when the thickness of the sheet P is thick.

[0191] Therefore, compared with the case of always detecting based on a fixed number of sheets, detection corresponding to the height of the sheet P can be achieved.

[0192] Furthermore, in the reduction amount detection process (1), in the small amount state control, based on the rising amount of the tray 42 that rises according to the height of the sheet P on the tray 42, the case where the remaining amount has decreased by a specified amount is detected.

[0193] Therefore, compared with the case of detecting the remaining amount based on the number of sheets carried out, simplification of the control can be achieved.

[0194] In addition, in the small amount state control, if the blowing amount of air used to float the sheet P is controlled to raise the sheet P, compared with the case of raising the tray 42, the mechanism for raising the sheet can be simplified.

[0195] Moreover, in the small amount state control, the rising amount of the tray 42 is controlled to raise the sheet P.

[0196] Therefore, compared with the case of controlling the blowing amount of air that floats the sheet P, facilitation of the height adjustment of the sheet P can be achieved.

[0197] Furthermore, in the small amount state control, the rising amount of the tray 42 is made larger when the thickness of the sheet P is thick than when the thickness of the sheet P is thin.

[0198] Thereby, compared with the case where the rising amount is always fixed, the rising of the tray 42 corresponding to the sheet thickness can be achieved.

[0199] In addition, in the small amount state control, the rising amount of the tray 42 is made larger when the width dimension of the sheet P is wide than when the width dimension of the sheet P is narrow.

[0200] Thereby, compared with the case where the rising amount is fixed regardless of the sheet width, the rising of the tray 42 corresponding to the sheet width can be achieved.

[0201] Moreover, in the small amount state control, the ascending amount of the tray 42 is made larger when the length dimension of the sheet P is longer than when the length dimension of the sheet P is shorter.

[0202] Thereby, compared with the case where the ascending amount is fixed regardless of the sheet length, the ascending of the tray 42 corresponding to the sheet length can be achieved.

[0203] Furthermore, in the case where the tray 42 ascends to a position higher than the reference height for detecting a small amount by an excess amount, when making the tray 42 ascend by an ascending amount in the small amount state which is larger than the ascending amount in the normal state control, make the tray 42 ascend by a subtraction amount obtained by subtracting the excess amount from the ascending amount in the small amount state.

[0204] Thereby, compared with the case where the ascending amount in the small amount state control is fixed, the ascending of the tray 42 corresponding to the case where the sheet supply amount to the tray 42 is small can be achieved.

[0205] Specifically, in the case where the tray 42 ascends to a position higher than the reference height 96, the excessive ascending of the tray 42 can be suppressed.

[0206] In addition, in the present embodiment, the case where the remaining amount of the sheet is small is detected based on the operating state of the small amount sensor 86 of the small amount detector 56, but it is not limited thereto.

[0207] For example, the case where the remaining amount of the sheet is small may also be detected based on the ascending drive time counted from the state where the tray 42 descends to the lower dead point, or the drive pulse number of the drive motor 72, and moreover, the case where the remaining amount of the sheet is small may be displayed on the display panel.

[0208] In addition, the sheet conveying device 10 can also be referred to as a paper feeding device or a tray lifting device. The paper feeding device or the tray lifting device includes a lifting device 74, a floating device 54, a suction head 112, a conveying device 110, etc.

[0209] In the above embodiment, the so-called processor refers to a processor in a broad sense, including a general-purpose processor (such as a Central Processing Unit (CPU), etc.) or a dedicated processor (such as a Graphics Processing Unit (GPU), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a programmable logic device, etc.).

[0210] Furthermore, the operations of the processor in each of the above-described embodiments may be performed not only by a single processor but also by a plurality of processors located at physically separated positions in cooperation. Moreover, the order of the respective operations of the processor is not limited to the order described in each of the above-described embodiments and may be changed as appropriate.

Claims

1. A sheet conveying device, characterized in that, including a processor, when the processor detects that the remaining amount of the sheets lifted and transferred on the tray is small, the rising control for raising the sheets is changed from the normal state control to the small amount state control, when the processor detects that the remaining amount has decreased by a specified amount during the small amount state control, the sheets are raised by a small amount state rising amount that is more than the rising amount in the normal state control, when the tray is raised to a position higher than the reference height by a height threshold, the rising amount adjustment process is executed, where the reference height is for detecting the small amount before the sheets are carried out from the tray, in the rising amount adjustment process, the current height of the tray is subtracted from the reference height as the excess amount, and the subtraction amount is obtained by subtracting the excess amount from the small amount state rising amount, and the tray is raised by the subtraction amount.

2. The sheet conveying device according to claim 1, characterized in that, the processor detects the situation where the remaining amount is small and the situation where the remaining amount has decreased by a specified amount in different ways.

3. The sheet conveying device according to claim 2, characterized in that, the processor detects the situation where the remaining amount has decreased by a specified amount based on the number of sheets carried out from the tray after changing to the small amount state control.

4. The sheet conveying device according to claim 3, characterized in that, regarding the number of sheets for the detection, when the thickness of the sheets is thin, it is more than when the thickness of the sheets is thick.

5. The sheet conveying device according to claim 2, characterized in that, the processor detects the situation where the remaining amount has decreased by a specified amount based on the rising amount of the tray that rises according to the height of the sheets on the tray during the small amount state control.

6. The sheet conveying device according to any one of claims 1 to 5, characterized in that, the processor controls the blowing amount of the air used to float the sheets to raise the sheets during the small amount state control.

7. The sheet conveying device according to claim 1, characterized in that, the processor makes the rising amount of the tray more when the thickness of the sheets is thick than when the thickness of the sheets is thin during the small amount state control.

8. The sheet conveying device according to claim 1, characterized in that, the processor makes the rising amount of the tray more when the width dimension of the sheets is wide than when the width dimension of the sheets is narrow during the small amount state control.

9. The sheet conveying device according to claim 7 or 8, characterized in that, the processor makes the rising amount of the tray more when the length dimension of the sheets is long than when the length dimension of the sheets is short during the small amount state control.

10. A sheet conveying medium, characterized in that, causing a computer to execute the following process, that is: when it is detected that the remaining amount of the sheets lifted and transferred on the tray is small, the rising control for raising the sheets is changed from the normal state control to the small amount state control, When it is detected in the small amount state control that the remaining amount has decreased by a specified amount, the sheet is raised by a small amount state raising amount that is more than the raising amount in the normal state control. When the tray is raised to a position higher than the reference height by a height threshold, the raising amount adjustment process is executed, where the reference height is for detecting the small amount before the sheet is unloaded from the tray. In the raising amount adjustment process, the current height of the tray is subtracted from the reference height to obtain an excess amount, and the excess amount is subtracted from the small amount state raising amount to obtain a subtraction amount, and the tray is raised by the subtraction amount.

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