JP2014012572A - Paper feeder and image formation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold a position of a medium floating by being sprayed with gas at a preset position without adding a member.SOLUTION: A paper feeder comprises a spray member (6) for spraying a gas from the side of a medium (S) on the medium loaded on a loading member (2) when the medium is taken out, a spray control part (7) for performing control for changing a floating state of the medium (S) being sprayed with the gas by changing the gas sprayed on the medium by the spray member (6), discrimination means (C8B) for discriminating whether or not a preset condition where carrying capacity of the medium (S) is reduced is satisfied, and lifting control means (C8) for lifting the loading member (2) on the basis of a position of the uppermost surface of the medium (S) when the medium (S) is taken out and lifting the loading member (2) when the condition where the carrying capacity of the medium (S) is reduced is satisfied when the medium (S) is taken out.

Description

  The present invention relates to a sheet feeding device and an image forming apparatus.

  Regarding a conventional image forming apparatus, a technique described in Patent Document 1 below is known.

  In Japanese Patent Application Laid-Open No. 2010-111502 as Patent Document 1, warm air is blown to the side surface of the sheet bundle (S), the sheet bundle (S) is floated, and the sheet bundle (S) is prior to paper feeding. The ugly configuration is described. In the configuration described in Patent Document 1, the lift plate (31) on which the sheet bundle (S) is stacked is raised based on the signal from the position detection sensor (PS1) before the sheet feeding command is issued. When an input for feeding paper is made, a paper feed preparation period starts. During the sheet feeding preparation period, the sheet bundle (S) is spread by repeatedly raising and lowering the lift plate (31) while blowing warm air. Then, an intermittent sheet rolling operation is performed in which the lift plate (31) is repeatedly raised and lowered every time 10 sheets are fed until 100 sheets are continuously fed.

JP 2010-111502 A (“0064” to “0133”)

  This invention makes it a technical subject to hold | maintain the position of the medium which a gas blows and floats in a preset position, without adding a member.

In order to solve the technical problem, a paper feeding device according to claim 1 is provided.
A loading member on which the medium is loaded;
An extraction member for taking out the medium loaded on the loading member;
An elevating member for elevating the stacking member with respect to the take-out member;
A blowing member that blows gas from the side of the medium to the medium stacked on the stacking member when the medium is taken out;
A spray control unit that performs control to change the floating state of the medium to which the gas is sprayed by changing the gas sprayed to the medium by the spray member;
A discriminating means for discriminating whether or not a preset condition for reducing the conveyance capability of the medium is satisfied based on at least one of the information on the medium and the information on the environment;
When the medium is taken out, the stacking member is lifted based on the position of the uppermost surface of the medium, and when the medium is taken out, the stacking member is satisfied when a condition for reducing the transporting ability of the medium is satisfied. Elevating control means for raising
It is provided with.

The invention according to claim 2 is the paper feeding device according to claim 1,
An outlet from which the gas is blown;
The air volume control unit configured by an opening and closing member for opening and closing the outlet;
It is provided with.

The invention according to claim 3 is the paper feeding device according to claim 1 or 2,
The discriminating means for discriminating that the condition of reducing the conveyance capacity of the medium is satisfied when the type of the medium is equal to or more than a preset basis weight,
It is provided with.

In order to solve the technical problem, an image forming apparatus according to a fourth aspect of the present invention provides:
The paper feeding device according to any one of claims 1 to 3, which feeds a medium;
A recording unit for recording an image on a fed medium;
It is provided with.

According to the first and fourth aspects of the present invention, gas is blown and floated without adding a member as compared with the case where the stacking member is not raised when the condition for reducing the medium conveyance capability is satisfied. The position of the medium can be held at a preset position.
According to the second aspect of the present invention, as the opening / closing member is opened / closed, the blown-out gas can be inflated, and the ability to spread the medium can be improved.
According to invention of Claim 3, the medium more than the preset basic weight can be hold | maintained in the preset position.

FIG. 1 is an overall explanatory view of an image forming apparatus according to Embodiment 1 of the present invention. FIG. 2 is an explanatory diagram of a main part of the image forming apparatus according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram of a main part of the sheet feeding device according to the first exemplary embodiment, FIG. 3A is a plan view, and FIG. 3B is a side view. 4A and 4B are explanatory views of a main part of the spray member of Example 1, FIG. 4A is a cross-sectional view, and FIG. 4B is a perspective view of a shutter. FIG. 5 is a block diagram illustrating the functions of the control unit of the image forming apparatus according to the first embodiment. FIG. 6 is an explanatory diagram of a flowchart of raising / lowering control of the stacking member during sheet feeding according to the first embodiment. FIG. 7 is an explanatory diagram of a state of gas blowing according to the first embodiment, FIG. 7A is an explanatory diagram of a state in which the shutter starts to move from the closed position to the open position, and FIG. 7B is a shutter from the state illustrated in FIG. 7C is an explanatory view of a state detected by the shutter sensor, FIG. 7C is an explanatory view of a state where the shutter is further moved downward from the state shown in FIG. 7B and moved to the open position, and FIG. 7D is FIG. 7C. FIG. 7E is an explanatory diagram of a state in which the shutter starts to move toward the closed position from the state shown in FIG. 7, FIG. 7E is an explanatory diagram of a state where the shutter moves upward from the state shown in FIG. 7D and is no longer detected by the shutter sensor, and FIG. It is explanatory drawing of the state which the shutter moved further upwards from the state shown to 7E, and moved to the obstruction | occlusion position. FIG. 8 is an explanatory diagram of a time chart in the case where the condition for reducing the conveyance capability is not satisfied in the sheet feeding device according to the first exemplary embodiment. 9 is an explanatory diagram of a state of the recording sheet when the recording sheet of Example 1 is coated paper and has a small basis weight, FIG. 9A is an explanatory diagram of a state where the recording sheet is floating, and FIG. 9B is an explanatory diagram of FIG. 9A. FIG. 9C is an explanatory diagram of a state in which the recording sheet is sent out from the state shown in FIG. FIG. 10 is an explanatory diagram of a time chart in a case where the condition for reducing the conveyance capability is satisfied in the sheet feeding device according to the first exemplary embodiment. 11 is an explanatory diagram of the state of the recording sheet when the recording sheet is thick paper, FIG. 11A is an explanatory diagram of the state where the recording sheet is floating, and FIG. 11B is the recording sheet sent out from the state shown in FIG. 11A. FIG. 11C is an explanatory diagram of a state in which the position of the uppermost surface of the recording sheet is lowered. FIG. 11C is an explanatory diagram of a state in a conventional configuration in which the recording sheet is further fed out from the state illustrated in FIG. 11B and the uppermost surface of the recording sheet is further lowered. 11D is an explanatory diagram of a state in the configuration of the first embodiment in which the recording sheet is sent out after the stacking member is raised from the state illustrated in FIG. 11B and the uppermost surface is lowered, and FIG. 11E is an explanatory diagram of a state in which the recording sheet is not floating. It is.

Next, examples as specific examples of embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following examples.
In order to facilitate understanding of the following description, in the drawings, the front-rear direction is the X-axis direction, the left-right direction is the Y-axis direction, the up-down direction is the Z-axis direction, and arrows X, -X, Y, -Y, The direction indicated by Z and -Z or the indicated side is defined as the front side, the rear side, the right side, the left side, the upper side, the lower side, or the front side, the rear side, the right side, the left side, the upper side, and the lower side, respectively.
In the figure, “•” in “○” means an arrow heading from the back of the page to the front, and “×” in “○” is the front of the page. It means an arrow pointing from the back to the back.
In the following description using the drawings, illustrations other than members necessary for the description are omitted as appropriate for easy understanding.

(Description of Overall Configuration of Printer U of First Embodiment)
FIG. 1 is an overall explanatory view of an image forming apparatus according to Embodiment 1 of the present invention.
FIG. 2 is an explanatory diagram of a main part of the image forming apparatus according to the first embodiment of the present invention.
1 and 2, a printer U as an example of an image forming apparatus according to the first exemplary embodiment includes a printer main body U1, a feeder unit U2 as an example of a supply device that supplies a medium to the printer main body U1, and an image. A discharge unit U3 as an example of a discharge device that discharges a recorded medium, an interface module U4 as an example of a connection unit that connects between the main body U1 and the discharge unit U3, and an operation unit operated by a user And a UI.

(Description of Marking Configuration of Example 1)
1 and 2, the main body U1 of the printer is a control unit C1 for controlling the image forming apparatus U or an information transmitting apparatus connected to the outside of the image forming apparatus U via a dedicated cable (not shown). A communication unit (not shown) that receives image information transmitted from the print image server COM as an example, a marking unit U1a as an example of an image recording unit that records an image on a medium, and the like. Connected to the print image server COM is a personal computer PC as an example of an image transmission device that is connected through a cable or a line such as a LAN (Local Area Network) and that transmits image information to be printed by the printer U. Yes.
The marking unit U1a prints photoconductor drums Py, Pm, Pc, Pk for each color of Y: yellow, M: magenta, C: cyan, K: black, and photographic images as an example of an image carrier. A photosensitive drum Po for glossing the image. The photosensitive drums Py to Po have a surface made of a photosensitive dielectric.

1 and 2, around the black photosensitive drum Pk, along the rotation direction of the photosensitive drum Pk, a charger CCk, an exposure device ROSk as an example of a latent image forming device, a developing device Gk, A primary transfer roll T1k as an example of a primary transfer unit and a photoconductor cleaner CLk as an example of a cleaning unit for an image carrier are disposed.
Similarly, around the other photosensitive drums Py, Pm, Pc, Po, chargers CCy, CCm, CCc, CCo, exposure units ROSy, ROSm, ROSc, ROSo, developing devices Gy, Gm, Gc, Go, 1 Next transfer rolls T1y, T1m, T1c, T1o, and photoconductor cleaners CLy, CLm, CLc, CLo are arranged.
On an upper part of the marking unit U1a, toner cartridges Ky, Kc, Km, Kk, Ko containing a developer supplied to the developing devices Gy to Go are detachably supported as an example of a storage container.

Below each of the photosensitive drums Py to Po, an intermediate transfer belt B, which is an example of an intermediate transfer member and an example of an image carrier, is disposed. The intermediate transfer belt B is a photosensitive drum Py to Po. And the primary transfer rolls T1y to T1o. The back surface of the intermediate transfer belt B includes a drive roll Rd as an example of a drive member, a tension roll Rt as an example of a tension applying member, a walking roll Rw as an example of a meandering prevention member, and a plurality of examples of a driven member. The idler roll Rf, a backup roll T2a as an example of an opposing member for secondary transfer, a plurality of retract rolls R1 as an example of a movable member, and the primary transfer rolls T1y to T1o.
On the surface of the intermediate transfer belt B, a belt cleaner CLB as an example of an intermediate transfer member cleaner is disposed in the vicinity of the drive roll Rd.

A secondary transfer roll T2b as an example of a secondary transfer member is disposed opposite to the backup roll T2a with the intermediate transfer belt B interposed therebetween. Further, a contact roll T2c as an example of a contact member is in contact with the backup roll T2a in order to apply a voltage having a polarity opposite to the charging polarity of the developer to the backup roll T2a. A conveyance belt T2e as an example of a conveyance member is stretched between the secondary transfer roll T2b of Example 1 and a drive roll T2d as an example of a drive member arranged on the lower right.
The backup roll T2a, the secondary transfer roll T2b, and the contact roll T2c constitute the secondary transfer device T2 of Example 1. The primary transfer rolls T1y to T1o, the intermediate transfer belt B, the secondary transfer device T2, and the like. Thus, the transfer devices T1, B, and T2 of Example 1 are configured.

Below the secondary transfer device T2, paper feed trays TR1 and TR2 are provided as an example of a storage unit that stores a recording sheet S as an example of a medium. A pickup roll Rp as an example of a take-out member and a separating roll Rs as an example of a separating member are disposed diagonally to the right of each sheet feeding tray TR1, TR2. A conveyance path SH that conveys the recording sheet S extends from the separation roll Rs, and a plurality of conveyance rolls Rs as an example of a conveyance member that conveys the recording sheet S to the downstream side are arranged along the conveyance path SH. Yes.
As an example of an unnecessary portion removing device, the recording sheet S is set at a preset pressure on the downstream side in the conveyance direction of the recording sheet S with respect to the position where the conveyance paths SH from the two sheet feeding trays TR1 and TR2 merge. A deburring device Bt that removes unnecessary portions of the edge of the recording sheet S, that is, a deburring device Bt is disposed.

On the downstream side of the deburring device Bt, a detection device Jk for measuring the thickness of the recording sheet S passing therethrough and detecting a state in which a plurality of recording sheets S overlap each other, so-called double feeding is disposed. A correction roll Rc that corrects an inclination with respect to the conveyance direction of the recording sheet S, that is, a so-called skew, is disposed on the downstream side of the double-feed detection device Jk as an example of a posture correction device. On the downstream side of the correction roll Rc, a registration roll Rr as an example of an adjustment member that adjusts the conveyance timing of the recording sheet S to the secondary transfer device T2 is disposed.
The feeder unit U2 is also provided with paper feed trays TR1, TR2, paper feed trays TR3, TR4, etc., which are configured in the same manner as the pick-up roll Rp, the pick-up roll Rs, and the transport roll Ra. The conveyance path SH from TR4 merges with the conveyance path SH of the main body U1 of the image forming apparatus U on the upstream side of the double-feed detection device Jk.

A plurality of conveying belts HB that hold the recording sheet S on the surface and convey the recording sheet S to the downstream side are arranged downstream of the conveying belt T2e in the conveying direction of the recording sheet S.
A fixing device F is disposed on the downstream side in the conveyance direction of the recording sheet S with respect to the conveyance belt HB.
A cooling device Co that cools the recording sheet S is disposed on the downstream side of the fixing device F.
On the downstream side of the cooling device Co, a decurler Hd that applies pressure to the recording sheet S to correct the curvature of the recording sheet S, that is, a so-called curl, is disposed.
An image reading device Sc that reads an image recorded on the recording sheet S is disposed on the downstream side of the decurler Hd.

A reversing path SH2 as an example of a transport path branched from the transport path SH extending toward the interface module U4 is formed on the downstream side of the image reading device Sc. A first gate GT1 as an example of the switching member is disposed.
In the reversing path SH2, a plurality of switchback rolls Rb as an example of a conveying member capable of rotating forward and reverse are arranged. On the upstream side of the switchback roll Rb, a connection path SH3 is formed as an example of a transport path that branches off from the upstream portion of the reversing path SH2 and joins the downstream side of the branch section of the transport path SH with the reversing path SH2. Has been. A second gate GT2 as an example of a transfer direction switching member is disposed at a branch portion between the reversing path SH2 and the connection path SH3.

On the downstream side of the reversing path SH2, a folding path SH4 for reversing the conveyance direction of the recording sheet S, that is, for switching back, is disposed below the cooling device Co.
In the return path SH4, a switchback roll Rb as an example of a conveying member capable of rotating in the forward and reverse directions is disposed. In addition, a third gate GT3 as an example of a conveyance direction switching member is disposed at the entrance of the return path SH4.
The conveyance path SH on the downstream side of the return path SH4 merges with the conveyance paths SH of the paper feed trays TR1 and TR2.

In the interface module U4, a transport path SH extending toward the discharge unit U3 is formed.
The discharge unit U3 is provided with a stacker tray TRh as an example of a stacking container on which the recording sheets S to be discharged are stacked, and a discharge path SH5 branched from the transport path SH and extending to the stacker tray TRh is provided. Yes. In the conveyance path SH of the first embodiment, when an additional discharge unit and a post-processing device (not shown) are additionally mounted on the right side of the discharge unit U3, the recording sheet S is attached to the added device. It is configured to be transportable.

(Marking operation)
In the image forming apparatus U, when image information transmitted from the personal computer PC is received via the print image server COM, a job which is an image forming operation is started. When the job is started, the photosensitive drums Py to Po, the intermediate transfer belt B, and the like rotate.
The photosensitive drums Py to Po are driven to rotate by a driving source (not shown).
The chargers CCy to CCo are applied with a preset voltage to charge the surfaces of the photosensitive drums Py to Po.
The exposure units ROSy to ROSo output laser light Ly, Lm, Lc, Lk, Lo as an example of light for writing a latent image in response to a control signal from the control unit C, and output the photosensitive drums Py to Po. Write an electrostatic latent image on the charged surface.
The developing devices Gy to Go develop the electrostatic latent images on the surfaces of the photosensitive drums Py to Po into visible images.
The toner cartridges Ky to Ko replenish the developer consumed with the development in the developing devices Gy to Go.

The primary transfer rolls T1y to T1o are applied with a primary transfer voltage having a polarity opposite to the charged polarity of the developer, and transfer the visible image on the surface of the photosensitive drums Py to Po to the surface of the intermediate transfer belt B.
The photoreceptor cleaners CLy to CLo remove and clean the developer remaining on the surfaces of the photoreceptor drums Py to Po after the primary transfer.
When the intermediate transfer belt B passes through the primary transfer region facing the photosensitive drums Py to Po, the images are transferred and stacked in the order of O, Y, M, C, and K, and the secondary transfer device T2. Pass through the secondary transfer region Q4. In the case of a single color image, an image of only one color is transferred and sent to the secondary transfer area Q4.

The pickup roll Rp records from the paper feed trays TR1 to TR4 to which the recording sheet S is supplied according to the size of the received image information, the designation of the recording sheet S, the size and type of the stored recording sheet S, and the like. The sheet S is sent out.
The separating roll Rs separates and separates the recording sheets S sent out from the pickup roll Rp one by one.
The deburring device Bt applies a preset pressure to the passing recording sheet S to remove burrs.
The double feed detection device Jk detects the double feed of the recording sheet S by detecting the thickness of the recording sheet S passing therethrough.
The correction roll Rc corrects the skew by bringing the recording sheet S passing therethrough into contact with a wall surface (not shown).
The registration roll Rr sends out the recording sheet S in accordance with the timing when the image on the surface of the intermediate transfer belt B is sent to the secondary transfer region Q4.

The secondary transfer device T2 records the image of the intermediate transfer belt B on the recording sheet S by applying a secondary transfer voltage having the same polarity as the developer charging polarity set in advance to the backup roll T2a via the contact roll T2c. Transfer to sheet S.
The belt cleaner CLB removes the developer remaining on the surface of the intermediate transfer belt B after the image is transferred in the secondary transfer region Q4 and cleans it.
The conveying belts T2e and HB hold the recording sheet S on which the image has been transferred by the secondary transfer device T2 on the surface and convey the recording sheet S to the downstream side.

The fixing device F includes a heating roll Fh as an example of a heating member and a pressure roll Fp as an example of a pressure member, and a heater as an example of a heat source is accommodated inside the heating roll Fh. Yes. The fixing device F fixes the unfixed image on the surface of the recording sheet S by heating the recording sheet S passing through the region where the heating roll Fh and the pressure roll Fp are in contact with each other while applying pressure.
The cooling device Co cools the recording sheet S heated by the fixing device F.
The decurler Hd applies pressure to the recording sheet S that has passed through the cooling device Co to remove the curvature of the recording sheet S, so-called curl.
The image reading device Sc reads an image on the surface of the recording sheet S that has passed through the decurler Hd.

When double-sided printing is performed, the recording sheet S that has passed through the decurler Hd is transported to the reversing path SH2 by being actuated by the first gate GT1, switched back by the folding path SH4, and then passed through the transport path SH. The image is retransmitted to the registration roll Rr and printing on the second side is performed.
The recording sheet S discharged to the discharge tray TRh is transported through the transport path SH and discharged to the stacker tray TRh. At this time, when the recording sheet S is discharged to the stacker tray TRh with the front and back sides reversed, the recording sheet S is once carried into the reversing path SH2 and the rear end of the recording sheet S in the conveying direction is the second gate GT2. , The second gate GT2 is switched and the switchback roll Rb rotates in the reverse direction, and is conveyed through the connection path SH3 and conveyed to the stacker tray TRh.
On the stacker tray TRh, the recording sheets S are stacked, and the stacking plate TRh1 is automatically raised and lowered so that the uppermost surface has a preset height according to the stacking amount of the recording sheets S.

(Description of the sheet feeding device of Embodiment 1)
FIG. 3 is an explanatory diagram of a main part of the sheet feeding device according to the first exemplary embodiment, FIG. 3A is a plan view, and FIG. 3B is a side view.
Next, a description will be given of the sheet feeding device according to the first embodiment including the sheet feeding trays TR1 to TR4, the pickup roll Rp, the separating roll Rs, and the like. However, since the configuration of each of the paper feed trays TR1 to TR4 is the same, a detailed description of the paper feed tray TR1 will be given, and a detailed description of the other paper feed trays TR2 to TR4 will be omitted.
In FIG. 3, the paper feed tray TR <b> 1 according to the first embodiment includes a tray body 1 as an example of a storage unit. The tray body 1 is configured in a box shape with the top opened. An end guide 1 a as an example of a first alignment member is supported on the left portion of the tray body 1. The end guide 1a contacts and aligns with the rear end of the recording sheet S in the conveyance direction. A side guide 1 b as an example of a second alignment member is supported at the rear portion of the tray body 1. The side guide 1b contacts and aligns with the end of the recording sheet S in the width direction.

Inside the tray body 1, a bottom plate 2 as an example of a stacking member is disposed. The bottom plate 2 is supported so as to be movable up and down with respect to the tray body 1. The bottom plate 2 can stack a bundle of recording sheets S on the upper surface. A lift 3 as an example of an elevating member is supported on the left end portion of the bottom plate 2.
The lift 3 has a wire 3a as an example of a string portion. One end of the wire 3 a is supported by the bottom plate 2. Above the bottom plate 2, a pulley 3b as an example of a pulley unit is rotatably supported by the printer main body U1. A wire 3a is hung on the pulley 3b. Outside the tray body 1, a lift motor 3c as an example of a drive source is disposed below the pulley 3b. The other end of the wire 3a is supported by the lift motor 3c. The lift motor 3c of the first embodiment is configured by a motor capable of forward and reverse rotation.

4A and 4B are explanatory views of a main part of the spray member of Example 1, FIG. 4A is a cross-sectional view, and FIG. 4B is a perspective view of a shutter.
In FIG. 4A, a blowing port 4 is formed at the upper end of the front portion of the paper feed tray body 1. A blower 6 as an example of a blowing member is supported at a position corresponding to the blowout port 4. In addition, the blower 6 of Example 1 incorporates a heater as an example of a heating member (not shown). Therefore, the blower 6 according to the first embodiment is configured to blow out warm air.
A shutter 7 as an example of an opening / closing member is supported between the blower 6 and the outlet 4 so as to be movable in the vertical direction. In FIG. 4B, a rack 7a as an example of a gear portion is formed on the right end portion of the shutter 7 so as to protrude rightward. A pinion gear 7b as an example of a gear meshes with the rack 7a. The rotation is transmitted to the pinion gear 7b from a shutter motor 7c as an example of a drive source. The shutter motor 7c according to the first embodiment is configured by a motor capable of forward and reverse rotation.

The shutter 7 according to the first embodiment is supported so as to be movable between an upper closed position where the blowout port 4 is closed and a lower open position where the blowout port 4 is opened.
A shutter sensor 8 as an example of a detection member is supported on the main body 1 of the paper feed tray. The shutter sensor 8 is disposed corresponding to the lower part of the moving range of the shutter 7. That is, when the shutter 7 is moved to the closed position, the shutter sensor 8 does not detect the shutter 7, and the shutter sensor 8 is moved to the open position from the closed position to the position where the shutter sensor 8 detects the shutter 7. A shutter sensor 8 is disposed.

In FIG. 3, the separating roll Rs according to the first embodiment includes a feed roll 11 as an example of a driving member. A retard roll 12 as an example of a driven member is supported on the feed roll 11 so as to face the feed roll 11. Rotation is transmitted to the feed roll 11 from a drive source (not shown).
A rotation arm 13 as an example of a support member for the take-out member is rotatably supported on the rotation shaft 11 a of the feed roll 11 with the rotation shaft 11 a of the feed roll 11 as a base end. A pickup roll Rp is supported on the left part of the rotating arm 13. The rotary arm 13 is movable between an upper standby position indicated by a solid line in FIG. 3 and a lower extraction position indicated by an underline in FIG. 3 in accordance with driving of a solenoid as an example of a drive source (not shown). It is supported by.
At the left end of the rotary arm 13, a detected portion 13a extending leftward is formed. Note that a level sensor 14 as an example of a detection member is disposed in a frame Fr as an example of a frame of the paper feed unit corresponding to the detected part 13a.

(Description of the control part of Example 1)
FIG. 5 is a block diagram illustrating the functions of the control unit of the image forming apparatus according to the first embodiment.
In FIG. 5, the control unit C of the printer main body U1 has an input / output interface I / O for inputting / outputting signals to / from the outside. In addition, the control unit C includes a ROM (read only memory) in which a program for performing necessary processing, information, and the like are stored. In addition, the control unit C includes a random access memory (RAM) for temporarily storing necessary data. The control unit C includes a central processing unit (CPU) that performs processing according to a program stored in a ROM or the like. Therefore, the control part C of Example 1 is comprised by the small information processing apparatus, what is called a microcomputer. Therefore, the control part C can implement | achieve various functions by running the program memorize | stored in ROM etc.

(Signal output element connected to the control unit C of the printer body U1)
The control unit C of the printer body U1 receives output signals from signal output elements such as the operation unit UI, the shutter sensor 8, the level sensor 14, the temperature sensor SN1, and the humidity sensor SN2.
The operation unit UI includes a power button UI1 as an example of a power-on unit, a display panel UI2 as an example of a display unit, a numeric input unit UI3, an arrow input unit UI4, and the like.
The shutter sensor 8 detects the position of the shutter 7.
The level sensor 14 detects the presence or absence of the detected portion 13 a of the rotating arm 13. That is, it is detected whether or not the position of the pick-up roll Rp supported by the rotary arm 13 has been lowered too much.
The temperature sensor SN1 measures temperature as an example of environmental information.
The humidity sensor SN2 measures humidity as an example of environmental information.

(Controlled elements connected to the control unit C of the printer body U1)
The control unit C of the printer main body U1 includes a drive circuit D1, a power supply circuit E, a blower drive circuit D2 as an example of a spray member drive circuit, and a shutter drive circuit D3 as an example of an open / close member drive circuit. The lift drive circuit D4 as an example of the lift member drive circuit, the solenoid drive circuit D5 as an example of the lift member drive circuit, and the take-out motor as an example of the drive source drive circuit of the take-out member The drive circuit D6 is connected to other control elements (not shown). The control unit C outputs those control signals to the circuits D1 to D6, E and the like.
D1: Driving circuit for driving source The driving circuit D1 for driving source drives the photosensitive drums Py to Po, the intermediate transfer belt B, and the like through a main motor M1 as an example of a driving source.

D2: Blower Drive Circuit The blower drive circuit D2 controls the blower 6 to control the blowing of gas.
D3: Shutter Drive Circuit The shutter drive circuit D3 controls the position of the shutter 7 by controlling the forward / reverse rotation of the shutter motor 7c.
D4: Lift Drive Circuit The lift drive circuit D4 controls the position of the bottom plate 2 by controlling forward / reverse rotation of the lift motor 3c.

D5: Solenoid Drive Circuit The solenoid drive circuit D5 controls the operation of the solenoid SL to move the pickup roll Rp supported by the rotary arm 13 up and down.
D6: Extraction Motor Drive Circuit The extraction motor drive circuit D6 rotationally drives the pickup roll Rp and the feed roll 11 via an extraction motor M2 as an example of an extraction drive source.

E: Power Supply Circuit The power supply circuit E includes a development power supply circuit Ea, a charging power supply circuit Eb, a transfer power supply circuit Ec, a fixing power supply circuit Ed, and the like.
Ea: Power supply circuit for development The power supply circuit Ea for development applies a development voltage to the development rolls of the development devices Gy to Go.
Eb: Power Supply Circuit for Charging The power supply circuit Eb for charging applies charging voltages for charging the surfaces of the photosensitive drums Py to Po to the chargers CCy to CCo, respectively.
Ec: Power supply circuit for transfer The power supply circuit Ec for transfer applies a transfer voltage to the primary transfer rolls T1y to T1o and the secondary transfer roll T2b.
Ed: Power supply circuit for fixing The power supply circuit for fixing Ed supplies power for heating the heater to the heating roll Fh of the fixing device F.

(Function of the control unit C of the printer body U1)
The control unit C of the printer main body U1 has a function of executing processing according to an input signal from the signal output element and outputting a control signal to each control element. That is, the control unit C has the following functions.
C1: Image Forming Control Unit The image forming control unit C1 controls the driving of each member of the printer U, the application timing of each voltage, and the like according to the image information input from the personal computer PC, thereby performing an image forming operation. Execute the job that is.
C2: Drive Source Control Unit The drive source control unit C2 controls the drive of the main motor M1 via the drive source drive circuit D1, and controls the drive of the photosensitive drums Py to Po and the like.

C3: Power Supply Circuit Control Unit The power supply circuit control unit C3 controls the power supply circuits Ea to Ed to control the voltage applied to each member and the power supplied to each member.
C4: Medium Information Storage Unit The medium information storage unit C4 stores medium information. The medium information storage unit C4 according to the first exemplary embodiment stores information on the type of medium such as the thickness, basis weight, and material of the recording sheet S regarding the recording sheets S accommodated in the paper feed trays TR1 to TR4. The medium type information stores information input in advance by the user from the operation unit UI. In Example 1, as the information of the thickness and basis weight of the medium, "plain paper" of a basis weight of 50~80 [g / ^{m 2],} a basis weight of 80 [g / ^{m 2]} is greater than "thick paper", grammage Information on the divided thickness such as “thin paper” whose amount is less than 50 [g / m ² ], and information on the basis weight to which a numerical value is directly input can be used. Further, in the first embodiment, information such as “plain paper”, “thick paper”, “OHP sheet”, and “coated paper” can be used as the material of the medium.

C5: Means for determining presence / absence of spraying The means for determining presence / absence of spraying C5 determines whether or not to perform gas spraying based on at least one of the type of medium and environmental information including temperature and humidity. The spraying presence / absence determining means C5 determines that the gas is sprayed when a preset spraying condition is satisfied. In the first embodiment, the case where the media are easily brought into close contact with each other and is easily taken out in a state where a plurality of media are overlapped is set as the spraying condition. That is, the spraying condition is set when it is preferable to assist the separation of the medium by blowing a gas on the medium instead of using only the rolling roll Rs. Specifically, when the paper type is a paper type that easily adheres to the surface, such as “coated paper” or “OHP sheet”, it is determined that the spraying condition is satisfied. Also, blown in the case of high temperature and high humidity, which tends to cause close contact between paper due to edge swelling due to moisture absorption of paper and surface tension of moisture, or close contact between paper due to coating agent on the surface of coated paper. It is determined that the attachment condition is satisfied.

C6: Control means for spraying member Control means C6 for the spraying member controls the blower 6 to control the spraying of gas. The spray member control means C6 according to the first embodiment operates the blower 6 to spray gas when it is determined by the spray presence / absence determination means C5 that the spraying conditions are satisfied. In the first embodiment, the blowing member control means C6 controls the blower 6 so as to blow out a gas having a preset air volume. In addition, it is not limited to the structure which blows off the gas of the preset air volume, It is also possible to set it as the structure which controls an air volume and temperature according to paper kind, temperature, humidity, etc.
C7: Opening / Closing Member Control Unit The opening / closing member control unit C7 controls the shutter motor 7c to control the lifting and lowering of the shutter 7. The controller C7 for the opening / closing member according to the first embodiment repeats the control of rotating the shutter motor 7c in the forward direction for a preset time and then rotating it in the reverse direction for the same time. Accordingly, the shutter 7 periodically moves between the closed position and the open position.

C8: Lift Control Means Lift control means C8 as an example of lift control means includes medium height detection means C8A, lift presence / absence determination means C8B, and opening / closing member position detection means. Shutter position detection means C8C, a lowering determination flag FL1, a shutter lowering determination means C8D as an example of an opening / closing member lowering determination means, and a lift as an example of a control means for an elevating drive source Motor control means C8E. The lift control means C8 raises the bottom plate 2 based on the position of the top surface of the medium when the recording sheet S is taken out. When the level sensor 14 is turned on, that is, when the level sensor 14 no longer detects the detected portion 13a, the lift control means C8 of the first embodiment is performed until the level sensor 14 is turned off, that is, the level sensor. The bottom plate 2 is raised until 14 detects the detected part 13a.
Further, when the recording sheet S is taken out, the lift control means C8 raises the bottom plate 2 when the condition for reducing the conveyance capability of the recording sheet S is satisfied. The lift control means C8 according to the first exemplary embodiment raises the bottom plate 2 by a preset increase amount when the condition for reducing the conveyance capability of the recording sheet S is satisfied.

C8A: Medium Height Detection Unit The medium height detection unit C8A detects the height of the recording sheet S based on the detection result of the level sensor 14. When the level sensor 14 detects the detected portion 13a when the pickup roll Rp moves to the position where the pickup roll Rp takes out, the medium height detection unit C8A according to the first exemplary embodiment detects the bundle of recording sheets S that the pickup roll Rp contacts. It is detected that the height of the top surface is higher than a preset position. Further, the medium height detection unit C8A according to the first exemplary embodiment is configured such that when the level sensor 14 does not detect the detected portion 13a when the pickup roll Rp moves to the position where the pickup roll Rp is taken out, the recording sheet S that the pickup roll Rp comes into contact with. It is detected that the height of the top surface of the bundle is lower than a preset position.

C8B: Elevating / Lowering Determining Unit The elevating / lowering determining unit C8B satisfies a preset condition for reducing the conveyance capability of the recording sheet S based on at least one of the information on the recording sheet S and the information on the environment. It is determined whether or not. The raising / lowering determination unit C8B according to the first exemplary embodiment determines that the condition for reducing the conveyance capability of the recording sheet S is satisfied when the type of the recording sheet S is equal to or more than a preset basis weight. Specifically, the basis weight of the recording sheet S is greater than 200 “g / m ² ”, that is, “thick paper” is used, and the shutter 7 is lowered from the preset position. In this case, it is determined that the condition for reducing the conveyance capability is satisfied.
C8C: Shutter position detection means The shutter position detection means C8C detects the position of the shutter 7 based on the detection result of the shutter sensor 8. Therefore, the shutter 7 is lowered when the shutter sensor 8 detects the shutter 7 from the non-detection state based on the detection result of the shutter position detection means C8C of the first embodiment. It is possible to determine that the shutter 7 is raised when the shutter 7 is detected and changed from the detected state to the non-detected state.

FL1: Lowering determination flag The initial value of the lowering determination flag FL1 is “0”, which is “1” when the shutter 7 is detected, and “0” when the shutter 7 is not detected.
C8D: Shutter Lowering Determination Unit The shutter lowering determination unit C8D determines whether the shutter 7 is lowered. The shutter lowering determination means C8D according to the first embodiment is configured such that the lower end of the lowering shutter 7 indicates the position of the shutter sensor 8 when the lowering determination flag FL1 is “0” and the shutter sensor 8 detects the shutter 7. It is determined that it has passed, that is, the shutter 7 is descending.

C8E: Lift Motor Control Unit The lift motor control unit C8E controls the forward / reverse rotation of the lift motor 3c via the lift drive circuit D4. The lift motor control means C8E of the first embodiment drives the lift motor 3c for a preset time when the lift control means C8 raises the bottom plate 2. Accordingly, the bottom plate 2 rises by a preset amount of rise according to the control of the lift motor control means C8E. The lift motor control means C8E operates the lift motor 3c in a state where the pickup roll Rp is moved to the standby position. That is, the bottom plate 2 is raised in a state where no paper is fed or in a period between the recording sheet S and the next recording sheet S during feeding.

C9: Control Unit for Extraction Member The control unit C9 for the extraction member includes an elevating control means C9A and a rotation control means C9B. The take-out member control means C9 takes out the recording sheet S by controlling the pickup roll Rp based on the timing of paper feeding.
C9A: Elevating Control Unit The elevating control unit C9A operates the solenoid SL to move the pickup roll Rp from the standby position to the position for taking it out based on the timing of paper feeding. Then, after the pickup roll Rp moves to the take-out position, when a preset time has passed based on the time when the recording sheet S taken out by the pickup roll Rp is delivered to the feed roll 11, the operation of the solenoid SL is performed. Stop and return the pickup roll Rp to the standby position.

C9B: Rotation Control Unit The rotation control unit C9B drives the take-out motor M2 based on the timing when the pickup roll Rp moves to the take-out position. Then, based on the time when the recording sheet S sent out by the pickup roll Rp and the feed roll 11 is transported by the downstream transport roll Ra, the driving of the take-out motor M2 is stopped.

(Explanation of flowchart of Example 1)
Next, a flow of control in the printer U according to the first embodiment will be described with reference to a flowchart, a so-called flowchart.

(Explanation of flowchart for raising / lowering control of stacking member being fed)
FIG. 6 is an explanatory diagram of a flowchart of raising / lowering control of the stacking member during sheet feeding according to the first embodiment.
6 is performed according to a program stored in the control unit C of the printer U. This process is executed in parallel with other various processes of the printer U. In the printer U according to the first exemplary embodiment, the processing illustrated in FIG. 6 is performed in parallel on each of the paper feed trays TR1 to TR4. Further, when the recording sheet S is replenished to the sheet feeding trays TR1 to TR4 and inserted into the printer main body U1, the bottom plate 2 is set to a preset height according to the position of the uppermost surface of the recording sheet S. Since the processing is simple with respect to the processing to be raised and held, illustration is omitted. In addition, when the recording sheet S is replenished, the process of lowering the bottom plate 2 to the lower end in accordance with the user's input to the operation unit UI is also easy to process, and is not shown. Furthermore, the process of rotating the shutter motor 7c forward for a preset time and then reversely rotating the same for the same time to raise and lower the shutter 7 is not shown because the process is simple. In addition, the process of lowering the pickup roll Rp every time when the recording sheet S is fed and raising the pickup roll Rp after a preset time has elapsed is simple because the process is simple. Omitted.

The flowchart shown in FIG. 6 is started when the printer U is turned on.
In ST1 of FIG. 6, it is determined whether or not an image forming operation, so-called job, has been started. If yes (Y), proceed to ST2. If no (N), repeat ST1.
In ST2, it is determined whether or not the spraying condition is satisfied. That is, it is determined whether or not the spraying condition is satisfied based on the type, temperature, and humidity of the recording sheet S used in the job. If yes (Y), proceed to ST3. If no (N), the process proceeds to ST12.
In ST3, the following processes (1) and (2) are executed. Then, the process proceeds to ST4.
(1) The blower 6 is operated.
(2) The raising / lowering operation of the shutter 7 is started.

In ST4, it is determined whether or not a condition for reducing the conveyance capability of the recording sheet S is satisfied. That is, it is determined whether or not the type of the recording sheet S is a paper type having a large basis weight. If yes (Y), proceed to ST5. If no (N), the process proceeds to ST12.
In ST5, it is determined whether or not the level sensor 14 is on. That is, it is determined whether or not the detected part 13a is not detected. If yes (Y), proceed to ST6. If no (N), the process proceeds to ST7.
In ST6, the lift motor 3c is operated to raise the bottom plate 2. Then, the process proceeds to ST11.

In ST7, it is determined whether or not the shutter sensor 8 is on. That is, it is determined whether or not the shutter sensor 8 is not detecting the shutter 7. If yes (Y), proceed to ST8. If no (N), the process proceeds to ST9.
In ST8, the lowering determination flag FL1 is set to “0”. Then, the process proceeds to ST11.
In ST9, it is determined whether or not the lowering determination flag FL1 = “0”. If yes (Y), proceed to ST10. If no (N), the process proceeds to ST11.
In ST10, the following processes (1) and (2) are executed. Then, the process proceeds to ST11.
(1) The lift motor 3c is operated for a preset time and number of times to raise the bottom plate 2.
(2) The lowering determination flag FL1 = “1”.
In ST11, it is determined whether or not the job is finished. If yes (Y), proceed to ST15. If no (N), the process returns to ST5.

In ST12, it is determined whether or not the level sensor 14 is on. That is, it is determined whether or not the detected part 13a is not detected. If yes (Y), the process proceeds to ST13. If no (N), the process proceeds to ST14.
In ST13, the lift motor 3c is operated to raise the bottom plate 2. Then, the process proceeds to ST14.
In ST14, it is determined whether or not the job is finished. If yes (Y), the process returns to ST1. If no (N), the process returns to ST12.
In ST15, the following processes (1) and (2) are executed. Then, the process returns to ST1.
(1) Stop the blower 6.
(2) Stop raising and lowering the shutter 7.

(Functions of the sheet feeding device of Embodiment 1)
FIG. 7 is an explanatory diagram of a state of gas blowing according to the first embodiment, FIG. 7A is an explanatory diagram of a state in which the shutter starts to move from the closed position to the open position, and FIG. 7B is a shutter from the state illustrated in FIG. 7C is an explanatory view of a state detected by the shutter sensor, FIG. 7C is an explanatory view of a state where the shutter is further moved downward from the state shown in FIG. 7B and moved to the open position, and FIG. 7D is FIG. 7C. FIG. 7E is an explanatory diagram of a state in which the shutter starts to move toward the closed position from the state shown in FIG. 7, FIG. 7E is an explanatory diagram of a state in which the shutter moves upward from the state shown in FIG. 7D and is no longer detected by the shutter sensor, and FIG. It is explanatory drawing of the state which the shutter moved further upwards from the state shown to 7E, and moved to the obstruction | occlusion position.

In the printer U of the first embodiment having the above-described configuration, when the paper feeding is started in the paper feeding device, the blower 6 operates when the spraying conditions are satisfied. Therefore, gas is blown from the side surface of the recording sheet S. At this time, the shutter 7 starts to move up and down.
In FIG. 7A, when the shutter 7 is moved to the closing position, the outlet 4 is closed by the shutter 7. Therefore, gas is not blown out. Therefore, the recording sheet S does not float and is in a state of being stacked on the bottom plate 2.
In FIG. 7B, when the shutter 7 moves toward the open position, gas is blown from the outlet 4 to the upper end portion of the recording sheet S. Accordingly, the recording sheet S at the upper end of the bundle of recording sheets S stacked on the bottom plate 2 floats. Therefore, the recording sheets S are separated and spread.

In FIG. 7C, when the shutter 7 completes moving to the open position, gas is blown from the outlet 4 onto the bundle of recording sheets S below the state shown in FIG. 7B. Therefore, many recording sheets S float compared to the state shown in FIG. 7B.
7D and 7E, when the shutter 7 moves from the open position toward the closed position, the position where the gas is blown moves upward, and the recording sheet S that has floated decreases.
In FIG. 7F, when the shutter 7 completes moving to the closed position, gas is not blown out. Accordingly, the force that floats the recording sheet S does not act, and the air layer gradually escapes due to the weight of the recording sheet S, and tries to return to the state where the recording sheet S is stacked on the bottom plate 2.
In this way, the shutter 7 repeats a series of operations shown in FIGS. 7A to 7F. Therefore, in Example 1, the position where the gas is blown varies as the shutter 7 moves up and down. Therefore, the gas blown onto the recording sheet S is inflated. Therefore, in comparison with the configuration in which a constant gas is blown onto the bundle of recording sheets S, the inflated gas is blown onto the recording sheet S in the first embodiment, and the ability to spread the recording sheet S is improved. Yes.

FIG. 8 is an explanatory diagram of a time chart in the case where the condition for reducing the conveyance capability is not satisfied in the sheet feeding device according to the first exemplary embodiment.
9 is an explanatory diagram of a state of the recording sheet when the recording sheet of Example 1 is coated paper and has a small basis weight, FIG. 9A is an explanatory diagram of a state where the recording sheet is floating, and FIG. 9B is an explanatory diagram of FIG. 9A. FIG. 9C is an explanatory diagram of a state in which the recording sheet is sent out from the state shown in FIG.
In FIG. 8, in the printer U according to the first embodiment, when the paper feeding operation is started, the pickup roll Rp moves to the take-out position, and the recording sheet S is sent out. When the paper feeding operation is started, the raising / lowering of the shutter 7 is started. The output value of the shutter sensor 8 changes when the shutter 7 is lowered from the closed position toward the open position and when the shutter 7 is raised from the open position to the closed position.
When the shutter 7 is lowered from the closed position toward the open position, as shown in FIGS. 7B to 7D and 9A, the recording sheet S that floats is in a large state. Therefore, the height of the uppermost surface of the recording sheet S tends to increase.

Here, in the case where the condition for reducing the conveyance capability is not satisfied, that is, in the case of a paper type having a relatively small basis weight of the coated paper, the recording sheet S tends to float. Therefore, it is easy to ensure a sufficient height of the uppermost surface of the floating recording sheet S.
Therefore, as shown in FIG. 9B, even when the recording sheets S are sequentially sent out as the paper is fed and the floating recording sheets S are reduced, in the case of a paper type having a relatively small basis weight of the coated paper, The recording sheet S that contacts the pickup roll Rp is easily secured. Therefore, as shown in FIG. 8, when the shutter sensor 8 is detecting the shutter 7, the level sensor 14 is difficult to detect the lowering of the pickup roll Rp. Therefore, it is difficult for the recording sheet S to be poorly fed.

Further, when the shutter 7 rises from the open position to the closed position and the output of the shutter sensor 8 changes from the presence of the shutter 7 to the absence, the state shown in FIG. 7E is obtained. Therefore, the recording sheet S that has floated decreases and falls to the bottom plate 2. At this time, if the recording sheet S is sent out and decreased with the paper feeding operation, the height of the uppermost surface of the recording sheet S is lowered. Therefore, as shown in FIG. 8, the level sensor 14 detects the lowering of the pickup roll Rp.
In FIG. 9C, when the level sensor 14 detects the lowering of the pickup roll Rp, the processing of ST12 to ST14 of FIG. 6 is executed, and the lift motor 3c operates. Therefore, the bottom plate 2 rises. Therefore, the height of the uppermost surface of the recording sheet S increases. Therefore, the occurrence of defective feeding of the recording sheet S is reduced.

FIG. 10 is an explanatory diagram of a time chart in a case where the condition for reducing the conveyance capability is satisfied in the sheet feeding device according to the first exemplary embodiment.
11 is an explanatory diagram of the state of the recording sheet when the recording sheet is thick paper, FIG. 11A is an explanatory diagram of the state where the recording sheet is floating, and FIG. 11B is the recording sheet sent out from the state shown in FIG. 11A. FIG. 11C is an explanatory diagram of a state in which the position of the uppermost surface of the recording sheet is lowered. FIG. 11C is an explanatory diagram of a state in a conventional configuration in which the recording sheet is further fed out from the state illustrated in FIG. 11B and the uppermost surface of the recording sheet is further lowered. 11D is an explanatory diagram of a state in the configuration of the first embodiment in which the recording sheet is sent out after the stacking member is raised from the state illustrated in FIG. 11B and the uppermost surface is lowered, and FIG. 11E is an explanatory diagram of a state in which the recording sheet is not floating. It is.

  7B to 7D, 10, and 11, when the recording sheet S is a paper type having a relatively large basis weight such as thick paper, when the thickness of one recording sheet S is increased, the floating recording sheet S The total number of sheets decreases. Further, when the basis weight of the recording sheet S is relatively large, the recording sheet S becomes heavy and is difficult to float. Therefore, when the recording sheet S descends from the closed position toward the open position, the height of the top surface of the floating recording sheet S tends to be lower than that of plain paper or the like. Further, when the pickup roll Rp sends out the recording sheet S and the number of floating recording sheets S decreases, the uppermost surface of the recording sheet S is larger in the case of thick thick paper or the like than in the case of thin paper. The speed at which the height of the lower becomes easier.

Accordingly, even in the case of thick paper or the like, in the conventional configuration in which the processing of ST12 to ST14 in FIG. 6 is performed, the level sensor 14 controls the lowering of the pickup roll Rp during the period in which the recording sheet S is floating, as shown in FIG. May detect. That is, there is a possibility that the recording sheet S is taken out in a state where the lowering of the pickup roll Rp is detected while the recording sheet S is floating and the level sensor 14 detects the lowering of the pickup roll Rp.
In FIG. 11C, when the recording sheet S is taken out with the height of the pickup roll Rp being lowered, the front end in the conveyance direction of the recording sheet S is likely to come into contact with the wall surface 21 of the tray body 1. When the recording sheet S comes into contact with the wall surface 21 of the tray body 1, the conveyance resistance of the recording sheet S increases. In particular, the recording sheet S having a large basis weight is heavy and has a large basic conveyance resistance. That is, in addition to the basic transport resistance, the transport resistance associated with the contact with the wall surface 21 is accumulated. Further, if the height of the recording sheet S is low, the front end in the conveyance direction of the recording sheet S may come into contact with the retard roll 12 below the contact area between the feed roll 11 and the retard roll 12 of the separating roll Rs. is there. If the front end of the recording sheet S hits the retard roll 12, the conveyance resistance of the recording sheet S may be further increased. Further, when the height of the recording sheet S is low, the load that the pickup roll Rp supported by the rotating arm 13 presses against the recording sheet S decreases, and the conveyance force of the pickup roll Rp decreases.

Therefore, if the conveyance force for conveying the recording sheet S by the pickup roll Rp decreases and the conveyance resistance of the recording sheet S increases, slipping between the recording sheet S and the pickup roll Rp is likely to occur. That is, the conveyance capability of the recording sheet S is likely to be reduced, and there is a possibility that the recording sheet S may be poorly fed.
In the conventional configuration, as shown in FIG. 11C, after the lowering of the pickup roll Rp is detected by the level sensor 14, the bottom plate 2 is raised. Therefore, in the state shown in FIG. 11C, the recording sheet S when the level sensor 14 detects the lowering of the pickup roll Rp is sent out before the bottom plate 2 is raised. Therefore, there is a possibility that the bottom plate 2 will not rise in time for the poor feeding of the recording sheet S.

  In the conventional configuration, it is conceivable to provide a sensor for detecting the height of the uppermost surface of the recording sheet S in order to cope with the case of thick paper or the like. That is, it is conceivable that the bottom plate 2 is raised by detecting the height of the uppermost surface of the recording sheet S with a sensor before the pickup roll Rp is lowered to the position where the pickup roll Rp is taken out. However, if the sensor is provided separately, the cost increases. Moreover, even if a sensor is arranged, in the configuration in which the medium is detected by reflected light or ultrasonic waves, accurate detection is difficult due to the surface state of the medium, the curved shape, and the like. Further, the floating state of the medium is various in three dimensions, and even if the amount of floating at the position where the sensor is arranged is determined, the medium may not be at an accurate height.

  On the other hand, in the printer U according to the first exemplary embodiment, when the shutter 7 moves toward the open position in the case of thick paper or the like, the process of ST10 in FIG. 6 is performed. Therefore, as shown in FIG. 11D, before the level sensor 14 detects the lowering of the pickup roll Rp, the bottom plate 2 is raised. That is, when the conveyance capability tends to decrease, before the conveyance failure with the pickup roll Rp occurs, the position of the uppermost surface of the recording sheet S is raised in advance from the state shown in FIG. 11B as shown in FIG. 11D. I am letting. Therefore, it is possible to reduce the height of the top surface of the recording sheet S from being excessively reduced, and to reduce the occurrence of paper feed defects. Accordingly, without adding a member such as a sensor, the position of the recording sheet S that is blown and floated by the gas is set to a preset position, that is, a height higher than a height that can be fed without causing a feeding failure. It can be held in position.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to the said Example, A various change is performed within the range of the summary of this invention described in the claim. It is possible. Modification examples (H01) to (H08) of the present invention are exemplified below.
(H01) In the above-described embodiment, the printer U as an example of the image forming apparatus has been illustrated. However, the present invention is not limited to this. It is also possible to do.
(H02) In the above-described embodiment, the configuration in which the developer of five colors is used as the printer U is illustrated. However, the present invention is not limited to this, and for example, a single-color image forming apparatus, four colors or less, or six colors or more The present invention can also be applied to a multicolor image forming apparatus.

(H03) In the above-described embodiments, the specific numerical values and parameters illustrated can be arbitrarily changed according to the design and specifications.
(H04) In the above-described embodiment, a paper type having a large basis weight is exemplified as a condition for reducing the conveyance capability, but the present invention is not limited to this. For example, in a medium that easily adheres between sheets, such as an OHP sheet, if two media are in close contact, the weight of the medium is doubled and it is difficult to float. It is also possible to determine that the conditions to be satisfied are satisfied. In addition, depending on conditions such as temperature and humidity, it becomes difficult to float due to an increase in the weight of the medium due to moisture absorption in a high humidity environment, or adhesion of the medium is likely to occur in an environment where static electricity is likely to occur at low temperatures. It is also possible to determine that the condition satisfies the condition that the conveyance capacity is reduced. In addition, for example, the thickness of the medium can be used as a parameter instead of the basis weight.

(H05) In the above-described embodiment, the configuration using the shutter 7 is illustrated as an example of the spray control unit, but the configuration is not limited thereto. For example, it is possible to adopt a configuration in which the rotation speed of the blade for blowing inside the blower is changed. It is also possible to provide a baffle plate, a so-called louver, in the blower outlet and rotate the louver to control the wind direction. Further, the configuration is not limited to the closed position when the shutter 7 moves to the upper end, and the closed position can be set when the shutter 7 moves to the lower end.
(H06) In the first embodiment, as the configuration for raising and lowering the bottom plate 2 as an example of the stacking member, the lift 3 that raises and lowers the bottom plate 2 in a horizontal state is used, but is not limited thereto. It is also possible to use a conventionally known elevating member that lifts the bottom plate 2 so that the bottom plate 2 is inclined by lifting the pickup roll Rp side of the bottom plate 2 upward.

(H07) In the above-described embodiment, the configuration in which the paper feed trays TR1 to TR4 are used as the paper feed device of the present invention is exemplified, but the present invention is not limited to this. For example, the present invention can be applied to a manual feed tray or a document feed tray.
(H08) In the above-described embodiment, the configuration in which the type of the recording medium is input from the operation unit UI is exemplified, but the present invention is not limited to this. For example, it is also possible to arrange a device for measuring the thickness of the medium in the transport path SH, automatically detect the thickness of the medium, and use the detected thickness of the medium. Further, the medium material may be automatically detected based on the result of measuring the glossiness and fluorescence of the surface, and the detected medium material may be used.

2 ... Loading member,
3 ... Lifting member,
4 ... Blowout port,
6 ... spraying member,
7: Control unit for spraying, opening / closing member,
C8 ... Elevating control means,
C8B ... discrimination means,
Rp ... extraction member,
S ... medium,
U: Image forming apparatus,
U1a: Recording unit.

Claims (4)

A loading member on which the medium is loaded;
An extraction member for taking out the medium loaded on the loading member;
An elevating member for elevating the stacking member with respect to the take-out member;
A blowing member that blows gas from the side of the medium to the medium stacked on the stacking member when the medium is taken out;
A spray control unit that performs control to change the floating state of the medium to which the gas is sprayed by changing the gas sprayed to the medium by the spray member;
A discriminating means for discriminating whether or not a preset condition for reducing the conveyance capability of the medium is satisfied based on at least one of the information on the medium and the information on the environment;
When the medium is taken out, the stacking member is lifted based on the position of the uppermost surface of the medium, and when the medium is taken out, the stacking member is satisfied when a condition for reducing the transporting ability of the medium is satisfied. Elevating control means for raising
A paper feeding device comprising: An outlet from which the gas is blown;
The air volume control unit configured by an opening and closing member for opening and closing the outlet;
The sheet feeding device according to claim 1, further comprising: The discriminating means for discriminating that the condition of reducing the conveyance capacity of the medium is satisfied when the type of the medium is equal to or more than a preset basis weight,
The sheet feeding device according to claim 1, further comprising: The paper feeding device according to any one of claims 1 to 3, which feeds a medium;
A recording unit for recording an image on a fed medium;
An image forming apparatus comprising:

Images