JP4701954B2 - Paper feeding device, paper feeding method, or image forming apparatus - Google Patents

Description

  The present invention relates to a sheet feeding device, a sheet feeding method, and an image forming apparatus including the sheet feeding device, which are used in an image forming apparatus such as a copying machine, a FAX, a printer, and a multifunction machine. The present invention relates to a sheet feeding device, a sheet feeding method, and an image forming apparatus including the sheet feeding device that separates the top sheet of a sheet bundle one by one and feeds the sheet to the downstream side in the sheet conveyance direction.

  The sheet feeding device of the image forming apparatus is configured to pick up the top sheet of the stack of sheets stacked on the sheet feeding tray one by one by a pickup roller and feed it to the sheet feeding path. If the frictional resistance between the sheets placed on the sheet feeding tray is high, the sheets may be double fed.

As a technique for preventing the double feeding of the paper, techniques described in the following documents (1) and (2) are conventionally known.
(1) Patent Document 1 (Japanese Patent Laid-Open No. 2004-210463)
(2) Patent Document 2 (Japanese Patent Laid-Open No. 2004-244161)
In the techniques described in Patent Documents 1 and 2, a separation roller having a feed roller (feed roller) and a retard roller is installed immediately after the pickup roller. The conventionally known retard roller is provided with a one-way clutch or a friction brake with a torque limiter. The separating roller having the feed roller and the retard roller separates the sheets fed from the pickup roller one by one and conveys them downstream in the sheet conveying direction.

In recent printers, there are many requests for printing on various recording materials, and printing requests on special paper such as mail seal paper are increasing. Paper with glue such as mail seal paper has a higher coefficient of friction than plain paper, has a high incidence of troubles during paper feeding such as double feeding and pick-up mistakes, and may not be able to feed stably. is there.
As a technique for solving such a double feed trouble, a technique described in the following Patent Document (3) is conventionally known.
(3) Patent Document 3 (Japanese Patent Laid-Open No. 2000-143019)
FIG. 8 is an explanatory diagram of the prior art described in Patent Document 3. In FIG.
In the technique described in Patent Document 3, as shown in FIG. 8, an auxiliary roller 12 that can be normally rotated, reversed, stopped, and pressed can be provided at the rear end of the stacked sheets, and can be rotated normally and reversed at the front end. The half-moon type paper feed roller 13 is provided and has a function of forming a loop (curving paper) between the rollers (12, 13). In the technique described in Patent Document 3, the paper is separated by the loop, and when the paper is double-fed, the paper is further separated by the friction separation plate immediately after.

Japanese Patent Laid-Open No. 2004-210463 JP 2004-244161 A JP 2000-143019 A

(Problems of the technology described in Patent Document 1 and Patent Document 2)
In the case of the prior art described in Patent Document 1 and Patent Document 2, when using a postcard paper with glue applied to the entire surface of the paper or a processed paper that is easily charged with static electricity, the paper is strongly adhered to each other. In some cases, a pickup error may occur.
(Problems of the technology described in Patent Document 3)
In the paper feeding device described in Patent Document 3, it is necessary to detect the timing at which the paper feeding roller 13 comes into contact with the uppermost paper and the timing at which the auxiliary roller 12 comes off from the uppermost paper at the time of loop formation. Requires timing detection with extremely high accuracy. Depending on the detection accuracy, the uppermost sheet is pressed by the auxiliary roller 12, so that there is a problem that it becomes a conveyance resistance and cannot be fed. In addition, the operation timing of forward / reverse rotation and stop of the auxiliary roller 12 and increase of the pressing load by the electromagnetic clutch, forward rotation and stop of the paper feed roller 13 is very severe, and the control is complicated.

In view of the above circumstances, the present invention has the following description (O01) as a technical problem.
(O01) To provide a paper feeding device that can prevent double feeding of paper picked up from a paper feeding tray of an image forming apparatus, has a simple configuration, and is easy to control.

(Invention)
Next, the present invention devised to solve the above problems will be described. In order to facilitate correspondence with the constituent elements of the embodiments described later, the constituent elements of the present invention are not described. Add the code enclosed in parentheses.
The reason why the present invention is described in correspondence with the reference numerals of the embodiments described later is to facilitate the understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(First invention)
In order to solve the above-mentioned problems, the sheet feeding device (Rp1, Rp2, Rs; Rp1 ′, Rp2, Rs) of the first invention is characterized by comprising the following structural requirements (A01) to (A09) .
(A01) One of the sheet bundles of the sheet feed trays (TR1, TR1 ') disposed above the front end, which is the downstream end in the sheet conveyance direction, of the sheet feed trays (TR1, TR1') capable of accommodating the sheet bundle. a pressing position for pressing the sheet (S1) on turn, the paper and the release position away upwardly from the upper surface of the bundle, the set and the sheet bundle between the pressing position and said release position (S1, S2 ... A front end side paper pressing member (3, 3 ') movable between a reference position away from the upper surface of Sn) ,
(A02) The uppermost sheet in the sheet bundle of the sheet feed tray (TR1, TR1 ') is disposed above the rear end, which is the upstream end in the sheet conveyance direction of the sheet feed tray (TR1, TR1'). The rear end side paper take-out roll (7) which is movable between a paper take-out position for picking up the uppermost paper in contact with (S1) and a release position away from the uppermost paper (S1). ),
(A03) The paper feed trays (TR1, TR1 ′) are disposed at the rear end portion, which is the upstream end portion in the paper transport direction, and upstream from the rear end side paper take-out roll (7). The pressing position for pressing the rear end of the second sheet (S2) from the top of the sheet bundle in a state where the top sheet (S1) of the sheet bundle (TR1, TR1 ') has moved forward, and the sheet A rear-end-side paper pressing member (8) movable between a release position spaced upward from the upper surface of the bundle (S1, S2,... Sn).
(A04) The paper feed tray (TR1) is disposed at the front end portion, which is the downstream end portion in the paper transport direction, and on the downstream side of the front end side paper pressing member (3, 3 '). ) In the sheet bundle (S1, S2,... Sn) in contact with the top edge of the uppermost sheet, and the uppermost sheet (S1) is taken out from the uppermost sheet (S1). A front end side sheet that is movable between a release position separated from the sheet and a reference position that is set between the sheet take-out position and the release position and is separated from the upper surface of the sheet bundle (S1, S2,... Sn). Take-out roll (2),
(A05) A front end side turning lever (1) supported above the front end of the paper feed tray (TR1) so as to be rotatable about an axis extending in the paper width direction accommodated in the paper feed tray (TR1). ,
(A06) the front end side paper take-out roll (2) supported by the front end of the front end side turning lever (1) and the front end side paper pressing member (3) supported by the rear end;
(A07) After being supported so as to be rotatable about an axis extending in the paper width direction accommodated in the paper feed tray (TR1, TR1 ′) above the rear end portion of the paper feed tray (TR1, TR1 ′). End side turning lever (6),
(A08) The rear end side paper take-out roll (7) supported by the front end portion of the rear end side rotation lever (6) and the rear end side paper pressing member (8) supported by the rear end portion,
(A09) When the sheet feeding is started, the front end side rotation lever (1) is controlled to move the front end side sheet pressing member (3, 3 ') to the pressing position and to move the front end The side paper take-out roll (2) is moved to the release position, and the rear end side rotation lever (6) is controlled to move the rear end side paper pressing member (8) to the release position and The rear end side paper take-out roll (7) is moved to the paper take-out position and the front end of the uppermost sheet (S1) of the sheet bundle (S1, S2,. The uppermost sheet (S1) of the sheet bundle (S1, S2,... Sn) of the sheet feeding trays TR1, TR1 ′) is conveyed by the sheet take-out roll (7), and the sheet bundle (S1, S2... Sn) is conveyed. Curve the top sheet (S1) to form a loop,
In a state where a loop is formed on the sheet (S), the trailing end side turning lever (6) is controlled to move the trailing end side sheet pressing member (8) to the pressing position and the trailing end. The side paper take-out roll (7) is moved to the release position, and the rear end portion of the second paper (S2) from the top of the paper bundle (S1, S2,... Sn) is moved to the rear end side paper pressing member (8). ) And the rear end of the uppermost sheet (S1) of the sheet bundle (S1, S2,... Sn) of the sheet feed tray (TR1, TR1 ′) is the outer periphery of the rear end side sheet pressing member (8). Hold it in contact with the surface,
In a state where the rear end of the uppermost sheet (S1) of the sheet bundle (S1, S2,... Sn) is pressed by the outer peripheral surface of the rear end side sheet pressing member (8), the front end side rotation lever (1 ), The front end side paper pressing member (3) is moved to the reference position, and the front end side paper take-out roll (2) is moved to the reference position, so that the top of the loop is formed. The front end of the sheet (S1) is released to eliminate the loop, and the front end of the sheet (S1) is moved forward by the amount of the canceled loop.
In the state where the loop of the uppermost sheet (S1) of the sheet bundle (S1, S2,... Sn) is eliminated, the front end side pressing lever (1) is controlled to control the front end side sheet pressing member (3). Is moved to the release position, and the front end side sheet take-out roll (2) is moved to the sheet take-out position, so that the rear end of the second sheet (S2) from the top of the sheet bundle (S1, S2,... Sn). The uppermost sheet (S1) of the sheet bundle is conveyed by the front end side sheet take-out roll (2) in a state where the portion is pressed by the rear end side sheet pressing member (8).
Paper pickup control means (C4).

(Operation of the first invention)
In the sheet feeding device (Rp1, Rp2, Rs; Rp1 ′, Rp2, Rs) of the first invention having the above-described structural requirements (A01) to (A09 ), the sheet feeding (S1, S2,... Sn) can be accommodated. The front end side paper pressing member (3, 3 ') disposed above the front end which is the downstream end in the paper transport direction of the paper tray (TR1, TR1') is a sheet of the paper feed tray (TR1, TR1 '). a pressing position for pressing the sheet (S1) of the top flux, the a release position away upwardly from the upper surface of the sheet bundle is set between the release position and the pressing position and the sheet bundle (S1 , S2... Sn) and the reference position away from the upper surface .
The rear end side paper take-out roll (7) disposed above the rear end, which is the upstream end of the paper feed tray (TR1, TR1 ') in the paper transport direction, is in the state where it is moved to the paper take-out position. The top sheet (S1) is taken out by contacting the top sheet (S) of the sheet bundle in the tray (TR1, TR1 '). In the state of moving to the release position, the uppermost sheet (S1) is separated upward.
A rear end paper pressing member (arranged upstream of the rear end of the paper feed tray (TR1, TR1 ') which is the upstream end in the paper transport direction and upstream of the rear end side paper take-out roll (7). 8) When the uppermost sheet (S1) of the sheet bundle in the sheet feed tray (TR1, TR1 ′) moves forward and moves to the pressing position, the sheet bundle (S1, S2,... Sn) The rear end of the second sheet (S2) from the top is pressed. When moved to the release position, the sheet moves upward from the upper surface of the sheet bundle (S1, S2,... Sn).

In the sheet feeder (Rp1, Rp2, Rs) according to the first aspect of the present invention , the front end portion which is the downstream end portion in the sheet transport direction of the sheet feed tray (TR1) and the front end side sheet pressing member (3, 3 '). Also, the front end side paper take-out roll (2) arranged on the upper side on the downstream side is moved to the paper take-out position, and the uppermost sheet bundle (S1, S2,... Sn) of the paper feed tray (TR1). The top sheet (S1) is taken out in contact with the front end of the sheet. The front end side sheet take-out roll (2) is separated from the uppermost sheet (S1) when it is moved to the upper release position. Further, the front end side sheet take-out roll (2) is set between the sheet take-out position and the release position, and is movable to a reference position away from the upper surface of the sheet bundle (S1, S2,... Sn).
Therefore, the front end side paper take-out roll (2) has the top of the paper bundle stored in the paper feed tray TR1 in which the loop is eliminated and the front edge of the paper is moved forward of the paper feed tray (TR1). The sheet S1) can be conveyed forward.

In the paper feeding device (Rp1, Rp2, Rs) according to the first aspect of the invention , above the front end of the paper feeding tray (TR1), around the axis extending in the paper width direction accommodated in the paper feeding tray (TR1). The front end side rotation lever (1) supported so as to be rotatable is such that the front end portion moves upward when the rear end portion rotates downward, and the rear end portion moves when the front end portion rotates downward. Move upward. Therefore, in the second aspect of the first invention, one of the front end side paper take-out roll (2) and the front end side paper pressing member (3) is lowered by rotating the front end side rotating lever (1). At the same time, the other can be raised. Accordingly, the front end side paper take-out roll (2) and the front end side paper pressing member (3) can be raised and lowered simultaneously with a simple mechanism.
When the rear end portion of the front end side rotation lever (1) is rotated downward, the front end side paper pressing member (3) supported by the rear end portion is the top sheet (S1) of the sheet bundle. Press the front end of the. In this state, after forming the loop on the uppermost sheet (S1), the front end side rotation lever (1) is rotated to rotate the front end side sheet pressing member (3) to the upper release position. When moved, the front end of the paper (S1) on which the loop is formed moves forward and the loop is eliminated. The front end side paper take-out roll (2) supported by the front end portion of the front end side rotation lever (1) in a state where the loop is eliminated contacts the front end portion of the paper (S1) from which the loop is eliminated. In this state, the uppermost sheet can be transported to the front of the sheet feed tray (TR1) by the front end side sheet take-out roll (2).

In the paper feeding device (Rp1, Rp2, Rs; Rp1 ′, Rp2, Rs) of the first invention, the paper feeding trays (TR1, TR1) are located above the rear end of the paper feeding tray (TR1, TR1 ′). ′) The rear end side turning lever (6) supported so as to be rotatable around an axis extending in the paper width direction is moved rearward when the front end is turned downward. In a state where the rear end portion is rotated downward, the front end portion moves upward. Therefore, according to the third aspect of the first invention, one of the rear end side paper take-out roll (7) and the rear end side paper pressing member (8) is rotated by rotating the rear end side rotating lever (6). The other can be raised simultaneously with lowering. Accordingly, the rear end side paper take-out roll (7) and the rear end side paper pressing member (8) can be raised and lowered simultaneously with a simple mechanism.
In a state where the front end portion of the rear end side rotation lever (6) is rotated downward, the rear end side sheet take-out roll (7) supported by the front end portion is the top sheet (S1) of the sheet bundle. ) To form the loop. In a state where the rear end portion of the rear end side rotation lever (6) is rotated downward, the rear end side paper pressing member (8) holds the loop of the uppermost paper (S1), and The trailing edge of the second sheet (S2) from the top of the sheet bundle (S1, S2,... Sn) is pressed.
Further, in the sheet feeding device (Rp1, Rp2, Rs; Rp1 ′, Rp2, Rs) of the first invention, the sheet pickup control means (C4) is configured to rotate the front end side when the sheet feeding is started. The moving lever (1) is controlled to move the front end side paper pressing member (3, 3 ') to the pressing position and the front end side paper take-out roll (2) to the release position, and By controlling the end side turning lever (6), the rear end side paper pressing member (8) is moved to the release position, and the rear end side paper take-out roll (7) is moved to the paper take-out position. Then, with the front end of the uppermost sheet (S1) in the sheet bundle (S1, S2,... Sn) pressed, the sheet feeding trays TR1, TR1 ′) are moved by the rear end side sheet take-out roll (7). The top sheet (S1) of the sheet bundle (S1, S2,... Sn) is conveyed to curve the top sheet (S1) of the sheet bundle (S1, S2,... Sn) to form a loop.
Further, the paper pickup control means (C4) controls the rear end side turning lever (6) in a state where a loop is formed on the paper (S), thereby the rear end side paper pressing member (8). Is moved to the pressing position and the trailing edge side sheet take-out roll (7) is moved to the release position, and the trailing edge of the second sheet (S2) from the top of the sheet bundle (S1, S2,... Sn) is moved. The rear end side paper pressing member (8) and pressing the rear end of the uppermost sheet (S1) of the sheet bundle (S1, S2... Sn) of the sheet feeding tray (TR1, TR1 ′). The rear end side paper pressing member (8) is pressed in contact with the outer peripheral surface.
Further, the sheet pickup control means (C4) has the rear end of the uppermost sheet (S1) of the sheet bundle (S1, S2,... Sn) pressed against the outer peripheral surface of the rear end side sheet pressing member (8). In this state, the front end side turning lever (1) is controlled to move the front end side paper pressing member (3) to the reference position and to move the front end side paper take-out roll (2) to the reference position. Then, the front end of the top sheet (S1) on which the loop is formed is released to cancel the loop, and the front end of the sheet (S1) is moved forward by the amount of the canceled loop.
Further, the paper pickup control means (C4) controls the front end side turning lever (1) in a state where the loop of the uppermost paper (S1) of the paper bundle (S1, S2,... Sn) is eliminated. The front end side paper pressing member (3) is moved to the release position and the front end side paper take-out roll (2) is moved to the paper take-out position, so that the top of the paper bundle (S1, S2,. In the state where the rear end portion of the second sheet (S2) is pressed by the rear end side sheet pressing member (8), the uppermost sheet (S1) of the sheet bundle is removed by the front end side sheet take-out roll (2). Transport.
Accordingly, the uppermost sheet (S1) of the sheet bundle in the sheet feed tray (TR1, TR1 ') is separated from the second and lower sheets (S2) and fed to the front of the sheet feed tray (TR1, TR1'). Is done.

( Second invention )
The image forming apparatus (U) according to the second aspect of the present invention is characterized by comprising the following structural requirements (C01).
(C01) Paper feeder of the first invention (Rp1, Rp2, Rs; Rp1 ′, Rp2, Rs).
( Operation of the second invention )
Wherein the image forming apparatus of the second invention having the configuration requirements (C01) (U), the sheet feeding device of the first invention (Rp1, Rp2, Rs; Rp1 ', Rp2, Rs) because it has a second invention sheet feeding device of an image forming apparatus (U) (Rp1, Rp2, Rs; Rp1 ', Rp2, Rs) is the sheet feeding device of the first invention (Rp1, Rp2, Rs; Rp1 ', Rp2, Rs) similar to In addition, the uppermost sheet (S1) of the sheet bundle (S1, S2,... Sn) in the sheet feeding tray (TR1, TR1 ′) can be separated from the other sheets (S2 to Sn) and taken out. Therefore, it is possible to prevent double feeding of paper when taking out the paper.

The above-described present invention has the following effect (E01).
(E01) It is possible to provide a paper feeding device that can prevent double feeding of paper picked up from the paper feeding tray of the image forming apparatus, has a simple configuration, and is easy to control.

Example 1
Next, examples 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 directions indicated by Z and -Z or the indicated sides are defined as front, rear, left, right, upper, lower, or front, rear, left, right, upper, and lower, 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.

FIG. 1 is an overall explanatory view of an image forming apparatus provided with a paper feeding device and a paper feeding method of the present invention.
In FIG. 1, an image forming apparatus (digital copying machine) U according to the first embodiment of the present invention includes a printer (image forming apparatus main body) U1, an image scanner U2, and an automatic document feeder U3.
The automatic document feeder U3 is supported on a platen glass PG on the upper surface of the image scanner U2.
The automatic document feeder U3 has a document feed tray TG1 on which a plurality of documents Gi to be copied are stacked. Each of the plurality of documents Gi placed on the document feed tray TG1 sequentially passes through the copy position on the platen glass PG (the press contact position of the platen roll GR1) and is discharged from the document discharge roll GR2 to the document discharge tray TG2. It is comprised so that.

The automatic document feeder U3 is rotatable with respect to the upper surface of the platen glass PG by a hinge shaft (not shown) extending in the left-right direction provided at the rear end portion (-X end portion). When a person puts it on the platen glass PG by hand, it is rotated upward.
The image scanner U2 has a UI (user interface) through which a user inputs an operation command signal such as a copy start.
An exposure optical system A for reading a document image is disposed below the transparent platen glass PG.
Reflected light from a document transported to the upper surface of the platen glass PG by the automatic document transport device U3 or a document (not shown) manually placed on the platen glass PG is passed through the exposure optical system A to a CCD ( It is converted into an electrical signal by a solid-state imaging device).

The IPS (image processing system) converts R, G, B (red, green, blue) electrical signals input from the CCD into Y, M, C, K (yellow, magenta, cyan, black) image data ( (Digital data) and temporarily stored, and the image data is output to the laser drive circuit DL as image data for forming a latent image at a predetermined timing.
The laser drive circuit DL outputs a laser drive signal to a laser diode (not shown) of a ROS (latent image forming apparatus) in accordance with the input image data. A power supply circuit for applying a bias voltage to the UI (user interface), the IPS and the laser driving circuit DL, and developing rolls R0y to R0k, transfer rolls T1y to T1k, a secondary transfer roll (sheet transfer member) T2b, which will be described later. Operations such as E are controlled by the controller C.
The laser drive circuit DL to which the four-color image data (laser drive data) of YMCK output from the IPS is input receives a laser drive signal of each color corresponding to the input image data of each color at a predetermined timing. Output to ROS (latent image forming apparatus).

The image carriers Py, Pm, Pc, and Pk are uniformly charged by the respective charging rolls (charging members) CRy to CRk, and then the laser beams L output from the ROSs (latent image forming apparatuses) of the respective colors. An electrostatic latent image is formed on the surface. The electrostatic latent images on the surfaces of the image carriers Py, Pm, Pc, and Pk are developed into toner images of the respective colors YMCK in the developing areas that face the developing devices Gy, Gm, Gc, and Gk, respectively. Each of the developing devices Gy, Gm, Gc, and Gk includes a developing container that accommodates toner of each color, and is electrostatically supported on the surface of the image carriers Py, Pm, Pc, and Pk. It has developing rolls R0y to R0k for conveying toner to the latent image and developing the toner image. The developer containers containing the respective color toners are configured to be supplied with the respective color toners from the toner cartridges Ty to Tk.
The developed toner images of the colors Y, M, C, and K are conveyed to a primary transfer region Q3 where the image carriers Py, Pm, Pc, and Pk and the endless intermediate transfer belt B are in contact with each other. The primary transfer rolls T1y to T1k disposed on the back side of the intermediate transfer belt B in each primary transfer region Q3 are opposite to the developer charging polarity at a predetermined timing from the power supply circuit E controlled by the controller C. A polar primary transfer voltage is applied. The toner images on the image carriers Py to Pk are primarily transferred to the intermediate transfer belt B in the primary transfer region Q3 facing the primary transfer rolls T1y to T1k. Residual toner on the surface of the image carrier Py, Pm, Pc, Pk after the primary transfer is removed by the image carrier cleaner CLp.

Each of the image carriers Py to Pk, each color ROS (latent image forming device), each color developing device Gy to Gk, each color toner image forming device UY (Py + ROS + Gy), UM (Pm + ROS + Gm), UC (Pc + ROS + Gc), UK (Pk + ROS + Gk) is configured.
Below the image carriers Py, Pm, Pc, Pk of the respective colors, a slide frame F1 is supported by a pair of left and right slide rails SR, SR so as to be slidable forward and backward (in a direction perpendicular to the paper surface). The slide frame F1 is supported so that the belt frame F2 of the belt module BM can be moved up and down between the raised operating position and the maintenance position moved downward. The configuration for moving the slide frame F1 back and forth and the configuration for moving the belt module BM up and down are conventionally known (see, for example, JP-A-8-171248), and various conventionally known configurations can be employed. .

The belt module BM includes a belt support roll (Rd, Rt, Rw) including the intermediate transfer belt B, a belt drive roll Rd, a tension roll Rt, a walking roll Rw, a plurality of idler rolls (free rolls) Rf, and a backup roll T2a. , Rf, T2a) and the four primary transfer rolls T1y to T1k. The intermediate transfer belt B is supported by the belt support rolls (Rd, Rt, Rw, Rf, T2a) so as to be rotatable in the arrow Ya direction.
A secondary transfer roll (sheet transfer member) T2b is disposed facing the surface of the intermediate transfer belt B in contact with the backup roll T2a. A transfer region (sheet transfer region) Q4 is formed. A secondary transfer voltage having a polarity opposite to the charging polarity of the developer is applied to the secondary transfer roll T2b from a power supply circuit E controlled by the controller C at a predetermined timing. The backup roll T2a disposed opposite to the secondary transfer roll T2b is grounded, and when a secondary transfer voltage is applied to the secondary transfer roll T2b, the secondary transfer roll T2b and A secondary transfer electric field is formed between the backup rolls T2a. The backup roll T2a and the secondary transfer roll T2b constitute a secondary transfer device T2.

The four primary transfer rolls T1y to T1k, the intermediate transfer belt B, the secondary transfer unit T2, and the like are formed on the surface of the image carrier Py to Pk of the toner image forming apparatus (UY, UM, UC, UK). A transfer device (T1y to T1k, B, T2) for transferring the toner image onto the paper S is configured.
A paper feed tray TR1 containing paper S (S1, S2,... Sn) and a paper feed transport path SH1 are provided below the printer (image forming apparatus main body) U1. The sheets S stored in the sheet feeding tray TR1 are fed one by one by a front end side paper pickup unit (front end side member) Rp1, a rear end side paper pickup unit (rear end side member) Rp2 and a separating roll Rs at a predetermined timing. The separated roll is taken out and conveyed to the registration roll Rr by the conveyance roll Ra. The sheet S transported to the registration roll Rr is transported to the secondary transfer area Q4 in time with the primary transfer of the multiple toner image or single color toner image moving to the secondary transfer area Q4.
When the sheet S passes through the secondary transfer region Q4, the secondary transfer voltage is applied to the secondary transfer roll T2b. Therefore, the color toner image primarily transferred over the intermediate transfer belt B is Secondary transfer is performed on the sheet S at once in the secondary transfer region Q4.
The residual toner is removed from the intermediate transfer belt B after the secondary transfer by the belt cleaner CLb. The sheet S on which the toner image is secondarily transferred is conveyed to the fixing nip Q5 by the post-transfer sheet guide SG and the sheet conveying belt HB.

When the sheet S conveyed by the sheet conveying belt HB passes through the fixing nip Q5, a pair of fixing units configured by a heating roll (heating rotation member) Fh and a pressure roll (pressure rotation member) Fp. Heat fixing is performed by a fixing device F having a roll (Fh + Fp).
The sheet S on which the toner image is fixed is conveyed to the sheet discharge path SH2 or the continuous recording conveyance path SH3. The sheet S conveyed to the sheet discharge path SH2 is discharged to the recording sheet discharge tray TRh, and the sheet conveyed to the continuous recording conveyance path SH3 is reversed and passes through the sheet circulation path SH4 to the registration roll Rr. Resent.
A sheet detection sensor SN1 that detects the leading edge of the sheet S is disposed on the downstream side of the separating roll Rs in the sheet conveyance direction.
The separating roll Rs, the front end side paper pickup unit Rp1 and the rear end side paper pickup unit Rp2 constitute the paper feeding device (Rp1, Rp2, Rs) of the first embodiment.
By the sheet feeding device (Rp1, Rp2, Rs), the registration roll Rr, the post-transfer sheet guide SG, the sheet conveying belt HB, the sheet feeding conveying path SH1, the sheet discharging path SH2, the continuous recording conveying path SH3, and the sheet circulation path SH4. A sheet conveying device SH is configured.

(Paper feeder)
FIG. 2 is an explanatory diagram of the sheet feeding device according to the first exemplary embodiment of the present invention, and is a block diagram (functional block diagram) illustrating each function provided in the control unit of the image forming apparatus according to the first exemplary embodiment.
1 and 2, the front end side paper pickup unit Rp1 of the paper feeding device (Rp1, Rp2, Rs) includes a front end side rotation lever 1 provided with a rotation shaft 1a at the center, and the front end side rotation. A front end side paper take-out roll 2 rotatably supported by the left end portion (−Y direction end portion) of the lever 1 and a front end side paper fixed to the right end portion (Y direction end portion) of the front end side rotating lever 1. And a pressing member 3. A gear G <b> 1 that transmits a rotational force to the front end side sheet take-out roll 2 is attached to the rotation shaft 1 a of the front end side rotation lever 1.
The rear end side paper pickup unit Rp2 of the paper feeding device (Rp1, Rp2, Rs) includes a rear end side rotary lever 6 provided with a rotary shaft 6a at the center and a left end of the rear end side rotary lever 6. A rear end side paper take-out roll 7 that is rotatably supported by the part, and a rear end side paper pressing member 8 that is fixed to the right end of the rear end side rotation lever 6. A gear G <b> 2 that transmits a rotational force to the rear end side sheet take-out roll 7 is attached to the rotation shaft 6 a of the rear end side rotation lever 6.

(Description of the control part of Example 1)
In FIG. 2, the controller C stores an I / O (input / output interface) that performs input / output of signals to / from the outside and adjustment of input / output signal levels, programs and data for performing necessary processing, and the like. ROM (read-only memory), hard disk, RAM (random access memory) for temporarily storing necessary data, CPU (central processing unit) that performs processing according to programs stored in the ROM, etc., and It is constituted by a microcomputer having a clock oscillator or the like, and various functions can be realized by executing a program stored in the ROM or the like.

(Signal input element connected to the controller C)
The controller C receives signals from signal input elements such as a UI (user interface) and a sheet detection sensor SN1.
The UI includes input keys such as a display unit UI1, a copy start key UI2, a numeric keypad UI3,..., Detects that they are input, and inputs a detection signal to the controller C.
The paper detection sensor SN1 detects the leading edge of the paper S that is fed from the paper feed tray TR1 and transported through the paper feed transport path SH1.

(Control element connected to the controller C)
The controller C is connected to a main motor drive circuit D1, a front end side paper pickup unit drive circuit D2, a rear end side paper pickup unit drive circuit D3, a paper take-out roll drive circuit D4, a power supply circuit E, and other control elements. These operation control signals are output.
The power supply circuit E includes development power supply circuits E1y to E1k, charging power supply circuits E2y to E2k, transfer power supply circuits E3y to E3k, a secondary transfer power supply circuit E3t, and a fixing power supply circuit E4.
The developing power supply circuits E1y to E1k apply a developing bias to the developing rolls R0y to R0k of the developing devices Gy to Gk.
The charging power supply circuits E2y to E2k apply a charging bias to the charging rolls CRy to CRk for forming toner images of the respective colors Y, M, C, and K.
The transfer power supply circuits E3y to E3k apply a transfer bias to the primary transfer rolls T1y to T1k. The secondary transfer power supply circuit E3t applies a secondary transfer bias to the secondary transfer roll T2b.
The fixing power supply circuit E4 supplies a heater heating current to the heater of the heating roll Fh of the fixing device F.

The main motor driving circuit D1 rotationally drives the image carrier PR, the developing rolls R0y to R0k of the developing devices Gy to Gk, the fixing device F, the conveying roll Ra, and the like via the main motor M1.
The front end side paper pickup unit drive circuit D2 controls the driving of the front end side paper pickup unit drive motor M2 and controls the rotation of the rotation shaft 1a of the front end side rotation lever 1, thereby the front end side paper pickup unit. Rp1 is rotationally controlled.
The rear end side paper pickup unit drive circuit D3 controls the driving of the rear end side paper pickup unit drive motor M3, and controls the rotation of the rotation shaft 6a of the rear end side rotation lever 6, thereby the rear end. The rotation of the side paper pickup unit Rp2 is controlled.
The paper take-out roll drive circuit D4 controls the paper take-out roll drive motor M4 and controls the rotation of the front end side paper take-out roll 2 and the rear end side paper take-out roll 7 through the gears G1 and G2.

(Function of the controller C)
The controller C has a function (control means) for executing a process according to an output signal from each signal output element and outputting a control signal to each control element. The function (control means) of the controller C will be described next.
C1: Job control means The job control means C1 controls the operations of the ROS, the image carriers Py to Pk, the primary transfer rolls T1y to T1k, the fixing device F, etc. according to the input of the copy start key UI2. A job (printing operation, copying operation) that is an image recording operation is executed.
C2: Main motor rotation control means The main motor rotation control means C2 controls the main motor drive circuit D1 to control the driving of the image carriers Py to Pk, the developing devices Gy to Gk, the fixing device F, and the like.

C3: Power supply circuit control means The power supply circuit control means C3 includes a development power supply control means C3A, a charging power supply control means C3B, a transfer power supply control means C3C, and a fixing power supply control means C3D, and controls the power supply circuit E. The power supply to each member of the image forming apparatus U is controlled.
C3A: Development power supply control means The development power supply control means C3A controls the development power supply circuits E1y to E1k to control the development bias.
C3B: Charging power supply control means The charging power supply control means C3B controls the charging power supply circuits E2y to E2k to control the charging bias.
C3C: Transfer Power Supply Control Unit The transfer power supply control unit C3C controls the transfer power supply circuits E3y to E3k to control the transfer bias. The secondary transfer bias is controlled by controlling the secondary transfer power supply circuit E3t.
C3D: Fixing power supply control means The fixing power supply control means C3D controls the fixing power supply circuit E4 to control the fixing temperature of the fixing device F.

C4: Paper Pickup Control Unit The paper pickup control unit C4 includes a front end side paper pickup unit rotation control unit C4A, a rear end side paper pickup unit rotation control unit C4B, a loop forming unit C4C, and a paper take-out roll rotation control unit. C4D.
C4A: Front end side paper pickup unit rotation control means The front end side paper pickup unit rotation control means C4A controls the rotation of the front end side paper pickup unit Rp1 so that the front end side rotation lever 1 is in a horizontal state. (Release position), the front end at the paper take-out position when the front end side turning lever 1 is turned counterclockwise, and the pressing position when the front end side turning lever 1 is turned clockwise. The side paper pickup unit Rp1 is moved.
C4B: Rear end side paper pickup unit rotation control means The rear end side paper pickup unit rotation control means C4B controls rotation of the rear end side paper pickup unit Rp2, so that the rear end side rotation lever 6 is horizontal. A reference position (release position) of the state, a loop formation position (sheet take-out position) in a state where the rear end side rotation lever 6 is rotated counterclockwise, and the rear end side rotation lever 6 is rotated clockwise. The rear end side paper pickup unit Rp2 is moved to the pressed position in the moved state.

C4C: Loop formation means The loop formation means C4C has a loop formation time measurement timer TM1, rotates the front end side paper pickup unit Rp1 to the pressing position, and loops the rear end side paper pickup unit Rp2. The loop formation time measurement timer TM1 measures the required time TM1a for loop formation while being rotated to the formation position, thereby forming a loop on the uppermost sheet S1 stacked on the paper feed tray TR1. To do.
C4D: Paper take-out roll rotation control means The paper take-out roll rotation control means C4D has a paper feed end time measuring timer TM2, and controls the rotation of the front end side paper take-out roll 2 and the rear end side paper take-out roll 7. The paper take-out roll rotation control means C4D detects that the paper sensor SN1 detects the leading edge of the paper S fed from the paper feed tray TR1, and then the paper feed end time measurement timer TM2 sets the paper feed end time TM2a. Measurement is performed, and the rotation of the front end side paper take-out roll 2 and the rear end side paper take-out roll 7 is stopped.

(Description of Flowchart of Paper Feed Control Processing in First Embodiment)
FIG. 3 is a flowchart of the paper feed control process of the image forming apparatus according to the first embodiment.
4A and 4B are explanatory views showing the steps of the paper feeding method according to the first embodiment. FIG. 4A is a diagram showing a state in which the front end side paper take-out roll and the rear end side paper take-out roll are rotated. FIG. FIG. 4C is a diagram illustrating a sheet front end pressing process in which the pickup unit is rotated to the pressing position and the trailing edge side sheet pickup unit is rotated to the loop forming position. FIG. 4C is a diagram illustrating a loop on the uppermost sheet stacked on the sheet feeding tray. 4D is a diagram showing a sheet rear end pressing step in which the rear end side paper pickup unit is rotated to the pressing position, and FIG. 4E is a diagram showing the front end side paper pickup unit being moved to the reference position. FIG. 4F is a diagram showing a state in which the front end side paper pickup unit is rotated to the paper take-out position.
The processing of each ST (step) in the flowchart of FIG. 3 is performed according to a program stored in the ROM or hard disk of the controller C. This process is executed in a multitasking manner in parallel with other various processes of the image forming apparatus U.

The flowchart shown in FIG. 3 is started when the image forming apparatus U is powered on.
In ST1 of FIG. 3, it is determined whether a print execution instruction has been input. That is, it is determined whether or not the copy start key UI2 is turned on. If yes (Y), the process proceeds to ST2. If no (N), ST1 is repeatedly executed.
In ST2, it is determined whether or not it is a paper feed timing. If yes (Y), the process proceeds to ST3, and, if no (N), the process returns to ST2.
In ST3, the front end side paper take-out roll 2 and the rear end side paper take-out roll 7 are rotated (see FIG. 4A).
In ST4, the following process is executed, and the process proceeds to ST5.
(1) The front end side paper pickup unit Rp1 is turned to the pressing position and the rear end side paper pickup unit Rp2 is turned to the loop forming position (paper takeout position) (see FIG. 4B).
(2) The required time TM1a for loop formation is set in the loop formation time measurement timer TM1.

In ST5, it is determined whether or not the loop formation time measurement timer TM1 has measured the required time TM1a for loop formation (whether or not TM1 has timed up). When the loop formation time measurement timer TM1 measures the required time TM1a for loop formation, a predetermined loop is formed on the uppermost sheet S stacked on the paper feed tray TR1 (see FIG. 4C). If yes (Y), the process proceeds to ST6, and, if no (N), ST5 is repeatedly executed.
In ST6, the rear end side paper pickup unit Rp2 is rotated to the pressed position (see FIG. 4D).
In ST7, the front end side paper pickup unit Rp1 is turned to the reference position (see FIG. 4E), and then the front end side paper pickup unit Rp1 is turned to the paper take-out position (see FIG. 4F).
In ST8, it is determined whether or not the sheet detection sensor SN1 has detected the leading edge of the sheet S. If yes (Y), the process proceeds to ST9, and, if no (N), ST8 is repeatedly executed.

In ST9, the paper feed end time TM2a is set in the paper feed end time measuring timer TM2.
In ST10, it is determined whether or not the paper feed end measurement timer TM2 has measured the paper feed end time TM2a (whether TM2 has timed up). If yes (Y), the process moves to ST11, and, if no (N), ST10 is repeatedly executed.
In ST11, the following process is executed, and the process proceeds to ST12.
(1) The front end side paper pickup unit Rp1 is rotated to the reference position (see FIG. 2).
(2) The rear end side paper pickup unit Rp2 is rotated to the reference position (see FIG. 2).
(3) Stop the front end side paper take-out roll 2 and the rear end side paper take-out roll 7 (see FIG. 2).
In ST12, it is determined whether or not the job is finished. If yes (Y), the process returns to ST1, and if no (N), the process returns to ST2.

(Operation of Example 1)
In the image forming apparatus U according to the first embodiment having the above-described configuration, when a print execution instruction is input (the copy start key UI2 is input) and the paper feed timing is reached, the front end side paper take-out roll 2 and the rear end side paper take-out roll 7 Is rotated (see FIG. 4A). Then, the front end side paper pickup unit Rp1 is turned to the pressing position and the rear end side paper pickup unit Rp2 is turned to the loop forming position (paper takeout position) (paper front end pressing of the paper feeding method shown in FIG. 4B). Process and front end side member moving process). The front end side paper pressing member 3 of the front end side paper pickup unit Rp1 presses the front end portion of the uppermost sheet (that is, the uppermost sheet of the sheet bundle S1, S2,... Sn) S1 stacked on the paper feed tray TR1. To do.
From this state, the loop formation time measurement timer TM1 measures the required time TM1a for loop formation, so that a loop is formed on the uppermost sheet S as the trailing edge side sheet take-out roll 7 rotates. (Loop formation process shown in FIG. 4C).

The rear end side paper pickup unit Rp2 is rotated to the pressing position. In a state where the rear end side paper pickup unit Rp2 is rotated to the pressing position, the rear end of the uppermost sheet S1 contacts the rear end side paper pressing member 8 and the loop is held. Further, the rear end side paper pressing member 8 presses the rear end portion of the second sheet S2 from the top loaded on the paper feed tray TR1 downward (the rear end portion pressing step and the rear end shown in FIG. 4D). End side member moving step).
The front end side paper pickup unit Rp1 is rotated to the reference position to release the loop (loop elimination step shown in FIG. 4E). At this time, since the rear end of the uppermost sheet S1 is in contact with the rear end side sheet pressing member 8, the front end portion of the sheet S1 is sent out in the sheet conveying direction when the loop is released (sheet feeding step).
After the loop is released, the front end side paper pickup unit Rp1 is rotated to the paper take-out position. At this time, the uppermost sheet S1 is conveyed to the sheet feeding conveyance path SH1 by the front end side sheet take-out roll 2 and the separating roll Rs. When the sheet S passes through the sheet feeding conveyance path SH1, the sheet detection sensor SN1 detects the leading edge of the sheet S1 (see FIG. 4F).

  When the paper feed end time measurement timer TM2 measures the paper feed end time TM2a after the paper detection sensor SN1 detects the leading edge of the paper S1, the front end side paper pickup unit Rp1 and the rear end side paper pickup unit Rp2 are detected. Rotate to the reference position (front end side roll separation step and rear end side roll separation step). Further, the rotation of the front end side paper take-out roll 2 and the rear end side paper take-out roll 7 is stopped.

In the image forming apparatus U including the paper feeding device (Rp1, Rp2, Rs) and the paper feeding method according to the first exemplary embodiment, the uppermost paper S1 stacked on the paper feeding tray TR1 and the top sheet S1 are formed from the top by the loop formation. Since an air layer is formed between the second sheet S2, the frictional resistance between the sheets is reduced. Further, the rear end portion of the second sheet S 2 from the top is pressed downward by the rear end side sheet pressing member 8. For this reason, it is possible to prevent the double feeding of the sheets that occurs when the uppermost sheet S1 is conveyed to the sheet feeding conveyance path SH1.
Further, the front end side paper pickup unit Rp1 lowers one of the front end side paper take-out roll 2 and the front end side paper pressing member 3 and simultaneously raises the other by rotating the front end side rotation lever 1. be able to. The rear end side paper pickup unit Rp2 lowers one of the rear end side paper take-out roll 7 and the rear end side paper pressing member 8 at the same time by rotating the rear end side rotation lever 6. Can be raised. Therefore, the paper feeding method and the paper feeding devices (Rp1, Rp2, Rs) are easier to control the paper feeding method than the conventional paper feeding methods and paper feeding devices (see References 1 to 3). The paper feeding device can be reduced in size and simplified.

(Example 2)
FIG. 5 is an explanatory diagram of the sheet feeding device and the sheet feeding tray according to the second embodiment. FIG. 5A is a block diagram (functional block diagram) illustrating each function included in the control unit of the image forming apparatus according to the second embodiment. FIG. 5B is a perspective view of the paper feed tray according to the second embodiment.
In the description of the second embodiment, components corresponding to those of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
The second embodiment is different from the first embodiment in the following points, but is configured in the same manner as the first embodiment in other points.
5B, the paper feed tray TR1 ′ according to the second embodiment includes paper positioning walls TR1a ′ and TR1a ′ that regulate the position of the paper S in the width direction (front-rear direction and X-axis direction). An inward projecting claw 9 is formed at the upper end of the sheet positioning wall TR1a ′ so as to project inward of the paper feed tray TR1 ′. The paper S stored in the paper feed tray TR1 ′ is fed in the direction of arrow Yb shown in FIG. 5B.

(Paper feeder)
5A, the front end side paper pickup unit Rp1 ′ according to the second embodiment includes a front end side rotation lever 1 ′ provided with a rotation shaft 1a ′ at the left end portion (−Y direction end portion), and the front end side rotation. And a front end side paper pressing member 3 ′ fixed to the right end (Y direction end) of the lever 1 ′.
The front end side paper pickup unit Rp1 ′, the rear end side paper pickup unit Rp2 and the separating roll Rs constitute a paper feeder (Rp1 ′, Rp2, Rs) of the second embodiment.

(Description of Control Unit of Example 2)
In FIG. 5A, a controller C is a ROM that stores I / O (input / output interface) for input / output of signals to / from the outside and adjustment of input / output signal levels, programs and data for performing necessary processing, (Read-only memory), hard disk, RAM (random access memory) for temporarily storing necessary data, CPU (central processing unit) for processing according to programs stored in the ROM, etc., and clock It is composed of a microcomputer having an oscillator or the like, and various functions can be realized by executing a program stored in the ROM or the like.

(Control element connected to the controller C)
The controller C is connected to a main motor drive circuit D1, a front end side paper pickup unit drive circuit D2 ', a rear end side paper pickup unit drive circuit D3, a paper take-out roll drive circuit D4', a power supply circuit E, and other control elements. And output their operation control signals.
The front end side paper pickup unit drive circuit D2 ′ controls the drive of the front end side paper pickup unit drive motor M2 ′ and controls the rotation of the rotation shaft 1a ′ of the front end side rotation lever 1 ′, thereby controlling the front end. The side paper pickup unit Rp1 ′ is controlled to rotate.
The paper take-out roll drive circuit D4 'controls the paper take-out roll drive motor M4' to control the rotation of the rear end side paper take-out roll 7 through the gear G2.

(Function of the controller C of the second embodiment)
The controller C according to the second embodiment has a function (control means) for executing a process according to an output signal from each signal output element and outputting a control signal to each control element. The function (control means) of the controller C will be described next.
The function of the controller C of the second embodiment shown in FIG. 5 is different from the function of the controller C of the first embodiment shown in FIG. In the description of the controller C of the second embodiment, the same functions as those of the controller C of the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
In the function of the controller C of the second embodiment shown in FIG. 5, the front end side paper pickup unit rotation control means instead of the front end side paper pickup unit rotation control means C4A and loop forming means C4C of the first embodiment shown in FIG. C4A ′ and loop forming means C4C ′ are provided.

C4: Paper Pickup Control Unit The paper pickup control unit C4 includes a front end side paper pickup unit rotation control unit C4A ′, a rear end side paper pickup unit rotation control unit C4B, a loop forming unit C4C ′, and a paper take-out roll rotation. Control means C4D.
C4A ′: Front end side paper pickup unit rotation control means The front end side paper pickup unit rotation control means C4A ′ is a reference position (release position) in which the front end side rotation lever 1 ′ is horizontal and the front end side rotation. The front end side paper pickup unit Rp1 'is rotationally controlled to a pressing position in a state where the lever 1' is rotated clockwise.
C4C ′: Loop forming means The loop forming means C4C ′ has a loop forming time measuring timer TM1, and rotates the front end side paper pickup unit Rp1 ′ to the pressing position, and the rear end side paper pickup unit. In a state where Rp2 is rotated to the loop formation position (paper take-out position), the loop formation time measurement timer TM1 measures the required time TM1a for loop formation, whereby the most loaded paper feed tray TR1 is loaded. A loop is formed on the upper sheet S1.

(Explanation of Flowchart of Paper Feed Control Processing in Embodiment 2)
FIG. 6 is a flowchart of the paper feed control process of the image forming apparatus according to the second embodiment.
FIG. 7 is an explanatory view showing each step of the paper feeding method of the second embodiment, FIG. 7A is a diagram showing a state where the rear end side paper take-out roll is rotated, and FIG. 7B is a diagram showing the front end side paper pick-up unit in the pressing position. FIG. 7C is a diagram illustrating a sheet front end pressing process in which the rear end sheet pickup unit is rotated to the loop forming position, and FIG. 7C is a loop forming process for forming a loop on the uppermost sheet loaded on the sheet feeding tray. FIG. 7D is a diagram showing a sheet trailing edge pressing process in which the trailing edge side paper pickup unit is rotated to the pressing position, and FIG. 7E is a diagram showing the leading edge sheet pickup unit moving to the reference position and releasing the loop. FIG. 10 is a diagram illustrating a sheet feeding process in which a stacked sheet is conveyed.
The flowchart of the paper feed control process shown in FIG. 6 is different from the flowchart of the paper feed control process shown in FIG. In the description of the flowchart of FIG. 6, the same step (ST) number is attached to the same process as the step of the flowchart of FIG. 3 and the detailed description is omitted.
In the flowchart of FIG. 6, ST3 ', ST4', ST7 'and ST11' are provided instead of ST3, ST4, ST7 and ST11 in the flowchart of FIG.

The flowchart shown in FIG. 6 is started when the image forming apparatus U is powered on.
In ST3 ′ of FIG. 3, the trailing edge side paper take-out roll 7 is rotated (see FIG. 7A).
In ST4 ′, the following processing is executed, and the process proceeds to ST5.
(1) The front end side paper pickup unit Rp1 ′ is turned to the pressing position, and the rear end side paper pickup unit Rp2 is turned to the loop forming position (paper takeout position) (see FIG. 7B).
(2) The required time TM1a for loop formation is set in the loop formation time measurement timer TM1.
In ST7 ′, the front end side paper pickup unit Rp1 ′ is rotated to the reference position (see FIG. 7E).
In ST11 ′, the following process is executed, and the process proceeds to ST12.
(1) The rear end side paper pickup unit Rp2 is rotated to the reference position (see FIG. 5).
(2) Stop the trailing edge side sheet take-out roll 7 (see FIG. 5).

(Operation of Example 2)
In the image forming apparatus U according to the second embodiment having the above-described configuration, when the central portion of the uppermost sheet S1 stacked on the sheet feeding tray TR1 ′ forms a loop, the inwardly protruding claws 9, 9 have the uppermost protrusions 9,9. The step of flipping both ends in the width direction of the paper S1 (both front and rear ends, both ends in the X-axis direction) (paper end flipping step during loop formation) occurs. By flipping both ends in the width direction of the uppermost sheet S1, it is possible to prevent a plurality of sheets S (S1, S2,... Sn) from simultaneously forming a loop.
Further, when the front end side paper pickup unit Rp1 ′ is rotated to the reference position, the uppermost paper S1 moves in the paper transport direction due to the rigidity of the paper (loop elimination step shown in FIG. 7E). Then, the paper is transported to the paper feed transport path SH1 by the separating roll Rs and the transport roll Ra (paper feeding process).
Depending on the type and rigidity of the paper, the distance moved in the paper conveyance direction may vary. However, since the sheet detection sensor SN1 for detecting the leading edge of the sheet S is disposed in the sheet feeding transport path SH1, the start and end of the sheet feeding operation can be set appropriately (sheet feeding step). ).

In addition, the paper feeding method and the paper feeding devices (Rp1 ′, Rp2, Rs) according to the second embodiment have the same effects as the paper feeding devices (Rp1, Rp2, Rs) according to the first embodiment. That is, it is possible to prevent double feeding of the sheets S (S1, S2,... Sn) generated when the uppermost sheet S1 is conveyed to the sheet feeding conveyance path SH1.
The rear end side paper pickup unit Rp2 simultaneously lowers one of the rear end side paper take-out roll 7 and the rear end side paper pressing member 8 by rotating the rear end side rotation lever 6. The other can be raised. Therefore, the paper feeding method and the paper feeding devices (Rp1, Rp2, Rs) are easier to control the paper feeding method than the conventional paper feeding methods and paper feeding devices (see References 1 to 3). The paper feeding device can be reduced in size and simplified.

(Example of change)
As mentioned above, although the Example of this invention was explained in full detail, this invention is not limited to each said Example, A various change is made within the range of the summary of this invention described in the claim. Is possible. Modified examples (H01) to (H05) of the present invention are exemplified below.
(H01) In each of the above embodiments, the image forming apparatus U is not limited to a copying machine, and can be applied to an image forming apparatus such as a FAX or a printer.
(H02) In the first embodiment, the front end side paper pressing unit 3 and the rear end side paper pressing member 8 of the front end side paper pickup unit Rp1 and the rear end side paper pickup unit Rp2 are omitted, and the front end side paper take-out roll 2 is omitted. In addition, by providing a clutch in the rear end side paper take-out roll 7, the rotation and stop of the front end side paper take-out roll 2 and the rear end side paper take-out roll 7 are controlled, and the uppermost stack loaded on the paper feed tray TR1 It is also possible to form a loop on the paper S.

(H03) In each of the above embodiments, the front end side paper pickup unit Rp1 and the rear end side paper pickup unit Rp2 are driven by the front end side paper pickup unit drive motor M2 and the rear end side paper pickup unit drive motor M3. not,
The front end side paper pickup unit Rp1 and the rear end side paper pickup unit Rp2 can be driven by a solenoid or the like.
(H04) In each of the above embodiments, the paper take-out roll drive circuit (D4, D4 ′) and the paper take-out roll drive motor (M4, M4 ′) are omitted, and the paper take-out roll (2, 7) is connected to the main motor M1. It is also possible to rotationally drive through the drive.
(H05) In the first embodiment, the front end side paper take-out roll 2 and the front end side paper pressing member 3 of the front end pickup unit Rp1 are connected by the front end side rotation lever 6, but the front end side rotation is not limited to this. It is also possible to omit the lever 6 and operate the front end side paper push roll 2 and the front end side paper pressing member 3 independently of each other. Further, in the rear end pickup unit Rp2, similarly to the front end pickup unit Rp1, the rear end side paper pushing roll 7 and the rear end side paper pressing member 8 can be independently operated.

FIG. 1 is an overall explanatory view of an image forming apparatus provided with a paper feeding device and a paper feeding method of the present invention. FIG. 2 is an explanatory diagram of the sheet feeding device according to the first exemplary embodiment of the present invention, and is a block diagram (functional block diagram) illustrating each function provided in the control unit of the image forming apparatus according to the first exemplary embodiment. FIG. 3 is a flowchart of the paper feed control process of the image forming apparatus according to the first embodiment. 4A and 4B are explanatory views showing the steps of the paper feeding method according to the first embodiment. FIG. 4A is a diagram showing a state in which the front end side paper take-out roll and the rear end side paper take-out roll are rotated. FIG. FIG. 4C is a diagram illustrating a sheet front end pressing process in which the pickup unit is rotated to the pressing position and the trailing edge side sheet pickup unit is rotated to the loop forming position. FIG. 4D is a diagram showing a sheet rear end pressing step in which the rear end side paper pickup unit is rotated to the pressing position, and FIG. 4E is a diagram showing the front end side paper pickup unit being moved to the reference position. FIG. 4F is a diagram showing a state in which the front end side paper pickup unit is rotated to the paper take-out position. FIG. 5 is an explanatory diagram of the sheet feeding device and the sheet feeding tray according to the second embodiment. FIG. 5A is a block diagram (functional block diagram) illustrating each function included in the control unit of the image forming apparatus according to the second embodiment. FIG. 5B is a perspective view of the paper feed tray according to the second embodiment. FIG. 6 is a flowchart of the paper feed control process of the image forming apparatus according to the second embodiment. FIG. 7 is an explanatory view showing each step of the paper feeding method of the second embodiment, FIG. 7A is a diagram showing a state in which the rear end side paper take-out roll is rotated, and FIG. FIG. 7C is a diagram illustrating a sheet front end pressing process in which the rear end sheet pickup unit is rotated to the loop forming position, and FIG. 7C is a loop forming process for forming a loop on the uppermost sheet loaded on the sheet feeding tray. FIG. 7D is a diagram showing a sheet trailing edge pressing process in which the trailing edge side paper pickup unit is rotated to the pressing position, and FIG. 7E is a diagram showing the leading edge sheet pickup unit moving to the reference position and releasing the loop. FIG. 10 is a diagram illustrating a sheet feeding process in which a stacked sheet is conveyed. FIG. 8 is an explanatory diagram of the prior art described in the cited document 3.

Explanation of symbols

1 ... Front end side turning lever,
2. Front end side paper take-out roll,
3, 3 '... front end side paper pressing member,
6 ... rear end side turning lever,
7: Rear end side paper take-out roll,
8 ... rear end side paper pressing member,
9,9 ... inward protruding nails,
Rp1, Rp2, Rs; Rp1 ′, Rp2, Rs...
S1 ... the top sheet in the stack,
S1, S2 ... Sn ... sheet bundle,
TR1, TR1 '... paper feed tray,
TR1a ', TR1a' ... paper positioning wall,
U: Image forming apparatus.

Claims (2)

A paper feeder provided with the following components (A01) to (A09) ,
(A01) a pressing position that is disposed above a front end portion that is a downstream end portion in the paper transport direction of a paper feed tray capable of storing a paper bundle, and presses the top paper of the paper bundle of the paper feed tray ; A front end side paper pressing member that is movable between a release position separated upward from the upper surface of the sheet bundle and a reference position set between the pressing position and the release position and separated from the upper surface of the sheet bundle. ,
(A02) Arranged above the rear end, which is the upstream end in the paper transport direction of the paper feed tray, contacts the top paper in the paper stack of the paper feed tray and takes out the top paper A rear end side paper take-out roll movable between a paper take-out position and a release position separated upward from the uppermost paper;
(A03) The uppermost sheet in the sheet bundle of the sheet feeding tray is disposed at the rear end portion that is the upstream end portion in the sheet conveyance direction of the sheet feeding tray and upstream from the trailing end side sheet take-out roll. A rear end side sheet that is movable between a pressing position that presses the rear end portion of the second sheet from the top of the sheet bundle and a release position that is spaced upward from the upper surface of the sheet bundle in a state where the sheet has moved forward Press member.
(A04) A front end portion that is a downstream end portion in the paper transport direction of the paper feed tray and is disposed on the lower upstream side of the front end side paper pressing member, and is the uppermost paper front end portion of the paper bundle of the paper feed tray. A sheet take-out position for picking up the top sheet in contact with the sheet, a release position spaced upward from the top sheet, and the sheet bundle set between the sheet take-out position and the release position. A front end side paper take-out roll movable between a reference position away from the upper surface of the paper,
(A05) A front end side turning lever supported above the front end portion of the paper feed tray so as to be rotatable around an axis extending in the paper width direction accommodated in the paper feed tray;
(A06) the front end side paper take-out roll supported by the front end of the front end side turning lever and the front end side paper pressing member supported by the rear end;
(A07) A rear end side rotation lever supported so as to be rotatable about an axis extending in the paper width direction accommodated in the paper feed tray above the rear end portion of the paper feed tray;
(A08) the rear end side paper take-out roll supported by the front end portion of the rear end side rotation lever and the rear end side paper pressing member supported by the rear end portion;
(A09) When the paper feeding is started, the front end side turning lever is controlled to move the front end side paper pressing member to the pressing position and to move the front end side paper take-out roll to the release position. And moving the rear end side paper pressing member to the release position and moving the rear end side paper take-out roll to the paper take-out position. With the front end of the top sheet in the bundle pressed, the top end paper in the paper tray is transported by the rear end side paper take-out roll to remove the top sheet in the stack. Curved to form a loop,
In a state where a loop is formed on the paper, the rear end side rotation lever is controlled to move the rear end side paper pressing member to the pressing position and to move the rear end side paper take-out roll to the release position. The rear end of the second sheet from the top of the sheet bundle is pressed by the rear end side sheet pressing member, and the rear end of the uppermost sheet in the sheet bundle of the paper feed tray is moved to the rear end. Press against the outer surface of the side paper pressing member,
In a state where the rear end of the uppermost sheet of the sheet bundle is pressed by the outer peripheral surface of the rear end side paper pressing member, the front end side rotation lever is controlled to move the front end side paper pressing member to the reference position. And the front end side sheet take-out roll is moved to the reference position to release the front end of the uppermost sheet on which the loop is formed to eliminate the loop, and the sheet by the amount of the eliminated loop. Move the front edge of the
In a state where the loop of the uppermost sheet of the sheet bundle is eliminated, the front end side rotation lever is controlled to move the front end side sheet pressing member to the release position and to move the front end side sheet take-out roll to the release position. The topmost sheet in the sheet bundle is moved by the front-end-side sheet take-out roll in a state where the sheet is moved to the sheet take-out position and the trailing edge of the second sheet from the top of the sheet bundle is pressed by the trailing edge side sheet pressing member. Transport,
Paper pickup control means. An image forming apparatus having the following configuration requirements (C01);
(C01) The sheet feeding device according to claim 1 .

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