JP2016008110A - Paper sheet transport device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a paper sheet transport device which can prevent stain and damage on a rear end or rear end surface of a paper sheet transported while being held by transport rollers.SOLUTION: A paper sheet transport device 1 comprises: two pairs of transport rollers 2, 3 which are provided downstream of a printing part and hold and convey a paper sheet; a holding control part 4 which oscillates follower rollers 2a, 3a of the transport rollers to control holding of the paper sheet; a detection part 8 which detects the end of the paper sheet and outputs a detection signal; and a control part which controls the holding control part at prescribed timing on the basis of the detection signal so that the holding pressure of the transport rollers applied to the rear end of the paper sheet becomes smaller than the holding pressure applied to a portion other than the rear end of the paper sheet and which prevent the rear end of the paper sheet from being held. Since the rear end of the paper sheet is not held by the transport rollers, stain and damage do not occur on the rear end or rear end surface of the paper sheet, and thereby the appearance is improved in especially book printing.

Description

  The present invention relates to a sheet conveying apparatus that conveys a sheet by sandwiching the sheet between conveying rollers, and in particular, can prevent the rear end surface of the sheet from being stained and scratched on the rear end surface of the sheet and thereby deteriorating the appearance. The present invention relates to the sheet conveying apparatus.

  As shown in the drawings in Patent Document 1, a printing apparatus 1 disclosed in Patent Document 1 includes a head unit 4 that prints on a sheet, and a sheet printed on the head unit 4 by a plurality of conveyance roller pairs. And a transport unit 3 that transports the transport path. In the transport path on the downstream side of the head unit in the transport direction, the nip pressure of the transport roller pair on the side closer to the head unit 4 is made smaller than the nip pressure of the transport roller pair on the farther side. As a result, it is difficult for the color material to be transferred from the paper in a state where the color material immediately after printing is not sufficiently fixed to the conveyance roller, and it is possible to reduce stains on the printed matter while suppressing a decrease in productivity. Has been.

JP 2012-45800 A

  According to the invention described in Patent Document 1, since the nip pressure of the conveying roller downstream of the head unit 4 is set to be smaller on the side closer to the head unit 4 than on the side farther from the head unit 4, the printed matter after printing is kept at a constant nip. Compared to the case of conveying by pressure, the ink is less likely to transfer to the conveying roller, and there is a possibility that the stain on the printing surface can be reduced, but the printed matter immediately after printing is conveyed across the entire length from the front end to the rear end. There was no change, and even though there was a difference in degree, it was not possible to completely avoid contamination of the printing surface by the conveyance roller coming into contact with the printing surface of the printed matter.

  Further, according to the knowledge of the present inventor, when a normal conveying roller as described above is used, particularly when printing a plurality of pages of paper in order to produce a booklet, the stain on the stamp surface for each page is acceptable. Even if it is inside, ink stains are generated on the rear end and rear end surface of the paper that exits the transport roller, and the rear end surface of the booklet that is produced by stacking this is positioned in the stacking direction (or on the position corresponding to the transport roller). A strip of dirt appears along the thickness of the booklet. The inventor of the present application noticed such a phenomenon, and as a result of diligent research on the cause, the inventors have obtained the following knowledge.

  FIG. 3 shows a state in which a sheet is conveyed by such a conventional conveying roller 100. The transport roller 100 is composed of a pair of upper and lower parts, and is divided into two in the axial direction with a predetermined interval. Although not shown in the figure, it is assumed that a plurality of pairs of such conveying rollers 100 are provided at a predetermined interval and the sheet P is continuously conveyed after printing.

  When the printed paper P is transported by the transport roller 100 configured as shown in FIG. 3, as described above, even if the invention described in Patent Document 1 is adopted, the peripheral surface of the transport roller 100 is stained with ink. In addition, it is not completely possible to prevent the ink stains from gradually accumulating. For this reason, the ink stains adhering to the peripheral surface of the transport roller 100 are transferred to the surface of the paper P as the paper P is transported, and particularly strongly adhere to the paper P by the mechanism described below at the rear end of the paper P. Therefore, it is considered that the phenomenon that the rear end surface stain S occurs at the rear end of the paper P as described above.

  That is, as shown in FIG. 4, when the paper P is nipped and conveyed by the upper and lower driven rollers 100a and the driving roller 100b constituting the conveying roller 100, the paper P is elastically deformed by the driven roller 100a and the driving roller 100b. The pressure is applied to a region of a certain area sandwiched between the inks, the ink is transferred from the marking surface to the peripheral surface of the transport roller 100, and the region receiving the pressure of the paper P moves toward the rear end. The closer the surface of the paper P is to the rear side (upstream side), the more ink tends to adhere from the transport roller 100.

  Then, as shown in FIG. 5, when the trailing edge of the sheet P comes out between the driven roller 100a and the driving roller 100b, the area where the sheet P receives pressure from the transport roller 100 decreases, Since the closer the portion is, the higher the pressure is received, it is considered that the stain due to the transfer of ink from the transport roller 100 becomes more conspicuous toward the rear end of the paper P. In addition, since there is a portion where the conveying roller 100 does not exist in the axial direction, damage to the paper P such as curling occurs due to a difference in pressure between a portion where there is no roller to which pressure is not applied and a paper edge where the pressure becomes the largest. There is also a case. Further, when the transport roller 100 is an elastic body, the rear end surface of the paper P may be soiled because the deformed transport roller 100 directly contacts the rear end surface of the paper P.

  The present invention has been made in view of such a conventional technique and its problems. In a paper transporting apparatus that transports a paper by sandwiching the paper with a transporting roller, when the trailing edge of the paper passes through the transporting roller, The main object of the present invention is to provide a paper conveying apparatus that can prevent the rear end portion and the rear end surface from being contaminated or damaged to impair the appearance.

The paper conveying apparatus according to claim 1 is:
At least two pairs of transport rollers arranged at a predetermined interval on the downstream side of the printing unit and sandwiching and transporting the paper;
A nipping control unit for controlling nipping of the sheet by the conveying roller;
A detection unit that detects an end of the sheet conveyed by the conveyance roller and outputs a detection signal;
A predetermined timing based on the detection signal of the detection unit so that the nipping pressure applied to the trailing edge of the sheet from the conveying roller is smaller than the nipping pressure applied to the portion other than the trailing edge of the sheet from the conveying roller. A control unit for controlling the clamping control unit,
It is characterized by comprising.

The paper conveying device according to claim 2 is the paper conveying device according to claim 1,
The control unit performs the nipping control before the rear end of the sheet conveyed by the second conveyance roller relatively downstream passes through the first conveyance roller relatively upstream. The holding pressure of the first conveying roller is reduced by controlling the portion.

The paper conveying device according to claim 3 is the paper conveying device according to claim 1 or 2,
The control unit controls the clamping control unit based on output timing of the detection signal, size information of a sheet to be conveyed, and a conveyance speed of the conveyance roller.

  According to the paper transport device of the first aspect, the detection unit detects the end of the paper transported by the transport roller, that is, the front end or the rear end of the paper, and outputs a detection signal. The control unit controls the nipping control unit at a predetermined timing when the trailing edge of the sheet passes the conveying roller based on the detection signal of the detecting unit, and the nipping pressure that the conveying roller applies to the trailing edge of the sheet The clamping control unit is controlled so as to be smaller than the clamping pressure applied to the other parts. As a method for reducing the clamping pressure with respect to the trailing edge of the sheet, the clamping pressure may be decreased or the clamping of the sheet may be released. Since the trailing edge of the sheet does not receive high pressure when it comes out of the conveying roller, the trailing edge or the trailing edge of the sheet is not damaged due to dirt or contact with the conveying roller, and the appearance is improved.

  According to the paper transport device of the second aspect, before the rear end of the paper transported by the second transport roller on the downstream side passes through the first transport roller on the upstream side, By reducing the nipping pressure of one transport roller, it is possible to continue transporting the sheet without causing dirt or damage to the trailing edge of the sheet.

  According to the paper conveyance device described in claim 3, the control unit controls the nipping control unit based on the output timing of the detection signal, the size information of the paper to be conveyed, and the conveyance speed of the conveyance roller. It is possible to accurately set the timing at which the nipping pressure of the conveying roller applied to the end of the sheet inside is reduced.

It is a whole block diagram including the control part of embodiment explaining paper conveyance. FIG. 5 is an overall configuration diagram of an embodiment in which a control unit for explaining a control operation when a trailing edge of a conveyed sheet passes through an opened conveyance roller is omitted. It is a perspective view explaining the structure and subject of the conventional conveyance roller. FIG. 10 is a front view illustrating sheet conveyance by a conventional conveyance roller. FIG. 10 is a front view for explaining the operation when the trailing edge of a sheet comes out of the conveyance roller in the conveyance of the sheet by the conventional conveyance roller.

A sheet transport apparatus 1 according to an embodiment will be described with reference to FIGS. 1 and 2.
As shown in FIG. 1, the sheet conveying apparatus 1 according to the embodiment includes at least two pairs of conveying rollers 2 and 3 arranged at a predetermined interval on the downstream side of a printing unit (not shown) arranged on the left side in the drawing. It has. In FIG. 1, a relatively upstream (left side in the figure) conveyance roller is referred to as a first conveyance roller 2, and a relatively downstream (right side in the figure) conveyance roller is referred to as a second conveyance roller 3. The sheet is conveyed from the left upstream to the right downstream as indicated by an arrow A in the figure.

As shown in FIG. 1, each pair of transport rollers 2 and 3 includes upper driven rollers 2a and 3a and lower drive rollers 2b and 3b. The drive rollers 2b and 3b are linked to the drive shafts of the drive motors M1 and M1, and the drive rollers 2b and 3b can be driven to rotate at a required rotational speed under the control of the control unit 10 described later. The driven rollers 2a and 3a are movable by a clamping control unit 4 that controls the clamping of the paper P in cooperation with the driving rollers 2b and 3b. That is, the driven rollers 2 a and 3 a are rotatably attached to the front end portion of the arm 5 that constitutes a part of the clamping control unit 4. The arm 5 is supported at its base end in a swingable manner, and the driven rollers 2a and 3a are urged by the urging means 6 so as to approach the drive rollers 2b and 3b. Further, a cam 7 constituting a part of the clamping control unit 4 is provided in contact with the arm 5 in the vicinity of the base end portion of the arm 5 and on the drive rollers 2b and 3b side. As shown in FIG. 1, the rotating shaft of the cam 7 is driven by a motor M2 that constitutes a part of the clamping control unit 4, and the motor M2 is controlled by the control unit 10 described later. It can be rotated by the required amount. Therefore, according to the clamping control unit 4, the arm 5 is swung against the biasing means 6 by rotating the cam 7 by the motor M2, and the driven rollers 2a and 3a are moved away from the driving rollers 2b and 3b. And can be controlled in a direction to reduce the clamping pressure on the paper P. Further, by rotating the cam 7 by the motor M2, the arm 5 is swung in the opposite direction by the urging force of the urging means 6, and the driven rollers 2a and 3a are moved in a direction approaching the driving rollers 2b and 3b. And can be controlled in a direction to increase the clamping pressure on the paper P.
In the present embodiment, the cam 7 and the motor M2 that drives the cam 7 are shown as means for swinging the driven rollers 2a and 3a and the arm 5 to which the driven rollers 2a and 3a are attached. However, the holding pressure applied to the paper by the driven roller can be variably controlled by various mechanical configurations and control methods. As another example, the clamping pressure applied to the paper can be variably controlled by moving the driven roller directly or indirectly by a solenoid.

  As shown in FIG. 1, a detection unit 8 that detects the edge of the paper P is provided upstream of the first transport roller 2. Although the detection principle of the paper P by the detection unit 8 is not particularly limited, it is possible to detect the end of the paper P conveyed by the conveyance rollers 2 and 3 and output a detection signal.

  As shown in FIG. 1, the sheet conveying apparatus 1 includes a control unit 10. An output terminal of the detection unit 8 is connected to the control unit 10, and a detection signal is input from the detection unit 8. The control unit 10 controls the motors M1 and M1 of the transport rollers 2 and 3 in accordance with a program stored in advance based on a detection signal from the detection unit 8 and a command or job information related to transport of the paper P acquired from the outside. By driving, the driving rollers 2b and 3b are driven to rotate at a necessary speed, and by controlling the motors M2 and M2 of the clamping control units 4 and 4 in the respective transport rollers 2 and 3, the driven rollers 2a and 3a and the driving roller The holding state of the paper P by 2b and 3b can be controlled.

  Note that the job information relating to the conveyance of the paper P includes, for example, size information of the paper P to be conveyed, speed information for conveying the paper P, and the like. The job information may be given to the control unit 10 by manual input from a control panel (not shown), or may be given via an external PC or the like or a storage medium.

According to the control unit 10, the output timing at which the detection signal is output from the detection unit 8, the size information of the paper P to be conveyed, and the conveyance speed information of the designated (or predetermined) conveyance rollers 2 and 3 Based on the above, by controlling the motor M2 of the nipping control unit 4, the nipping pressure of the sheet P by the conveying rollers 2 and 3 decreases in accordance with the timing when the trailing edge of the sheet P passes the conveying rollers 2 and 3. Thus, the clamping control unit 4 can be controlled.

  FIG. 1 is a diagram illustrating a state in which the paper P is being transported by the first and second transport rollers 2 and 3, and FIG. 2 is a diagram illustrating the state in which the rear end of the paper P is moved to the opened first transport roller 2. It is a figure which shows the state which passes. As shown in FIG. 1, when the paper P is being conveyed, the motor M <b> 2 of the clamping control unit 4 is operated, and the driven rollers 2 a and 3 a are set to the lower conveying position by the urging means 6, and each conveying roller 2 , 3 and the driven rollers 2a, 3a and the driving rollers 2b, 3b are in a state of sandwiching the paper P. As shown in FIG. 2, when the trailing edge of the sheet P being conveyed exits between the rollers, the conveyance roller corresponding to the trailing edge of the sheet P is activated by the motor M <b> 2 of the clamping control unit 4. The second driven roller 2a is set at the upper separation position. Although not shown, when the leading edge of the paper P enters the transport rollers 2 and 3, the driven rollers 2a and 3a and the driving rollers 2b and 3b are in a state of facing each other with a gap for receiving the paper.

  In the previous stage of the state shown in FIG. 1, when the paper P is discharged from a printing unit (not shown) in the previous stage and sent downstream, and the front end of the paper P passes through the detection unit 8, the detection unit 8 detects this. A detection signal is output to the control unit 10.

As shown in FIG. 1, the paper P passes through the first transport roller 2 and the second transport roller 3, is sandwiched by both the transport rollers 2 and 3, and is transported downstream.
The control unit 10 determines the size of the paper P, the speed of the paper P coming out of the printing unit, the distance between the detection unit 8 and the first transport roller 2 based on the timing when the front edge of the paper P passes the detection unit 8. The position of the paper P is grasped from the information. That is, the control unit 10 always knows the distance L1 between the detection unit 8 and the front end of the paper P.

  In FIG. 2, when the paper P is transported by the first transport roller 2 and the second transport roller 3, the rear end of the paper P eventually approaches the sandwiched portion of the first transport roller 2. The control unit 10 determines whether the detection unit 8 and the paper P are in the range of the size of the paper P, the conveyance speed of the paper P by the first and second conveyance rollers 2 and 3, the distance between the detection unit 8 and the first conveyance roller 2, and the like. The distance L2 from the front end is grasped, and the timing at which the rear end of the paper P passes the first transport roller 2 can be calculated. Based on the calculation result, the control unit 10 controls the nipping control unit 4 at the timing when the trailing end of the sheet P actually passes the first transport roller 2 and raises the driven roller 2 a of the first transport roller 2. Thus, the clamping with the driving roller 2b is released. The rear end of the paper P is not subjected to the clamping pressure by the first transport roller 2 and is not damaged or damaged. The paper P is transported to the second transport roller 3, passes through the first transport roller 2, and is sent downstream.

  Although not shown, if there is another transport roller on the downstream side of the second transport roller 3, the paper P is transferred to the other transport roller and transported further downstream. At this time, when the rear end of the sheet P passes through the second transport roller 3 by the same control as described above, the driven roller 3a is released upward, and the holding pressure is applied to the rear end of the sheet P. The conveyance is continued in such a manner that the nipping pressure is smaller (or the clamping pressure is smaller than that during the conveyance). If a detection unit is provided between the first conveyance roller 2 and the second conveyance roller 3 or on the downstream side of the second conveyance roller 3 and the edge of the sheet P is detected as appropriate, the sheet P Since the current position can be grasped more accurately, it is useful for the above control. 1 and 2, the detection unit 8 detects the front end of the paper P. However, the detection unit 8 may detect the rear end of the paper P, or may detect both. May be.

  The sheet conveying apparatus 1 of the present embodiment described above has at least two pairs of conveying rollers 2 and 3 as conveying rollers for conveying the sheet P. This is because the sheet P can be continuously conveyed if there are at least two pairs, and as described above, the conveyance of the sheet P is continued while performing the control to reduce the holding pressure of the conveyance roller with respect to the rear end of the sheet P. This is because at least two pairs of transport rollers are required. Also, the detection unit 8 for detecting the end of the paper P has one detection unit 8 upstream of the first transport roller 2 because the front end of the paper P is located upstream of the two pairs of transport rollers. This is because the position of the paper P can be grasped by integrating various information such as the paper size and the conveyance speed. However, as described above, three or more pairs of transport rollers may be arranged at a predetermined interval along the transport path, and the number of detection units is not necessarily one, but two as illustrated above. You may provide above.

  Select one of the booklet printing mode in which each page of a booklet composed of a considerable number of pages is printed continuously in each booklet and stacked in a booklet form, and the normal small number normal printing mode. In the image forming apparatus that can be executed, if the sheet conveying apparatus 1 according to the above-described embodiment is provided on the discharge side of the printing unit, the following effects can be obtained. That is, as described in the section “Problems to be Solved by the Invention”, according to the conventional paper transport device, when the booklet printing mode is executed, the stain on the printing surface for each page is within an allowable range. Even if this occurs, the trailing edge of each page is strongly held by the conveyance roller, and the trailing edge surface stains occur. Therefore, a stain band appears along the thickness direction of the booklet on the trailing edge surface of the booklet. However, according to the paper transport device 1 of the present embodiment, the clamping pressure with respect to the rear end of the paper P can be reduced, so that the rear end surface of the page does not become dirty, and each page is overlapped. It is possible to reliably avoid the problem that a stain band in the thickness direction is formed on the rear end face of the booklet to be produced.

DESCRIPTION OF SYMBOLS 1 ... Paper conveyance apparatus 2 ... 1st conveyance roller 3 ... 2nd conveyance roller 4 ... Nipping control part 8 ... Detection part 10 ... Control part P ... Paper M1, M2 ... Motor

Claims (3)

At least two pairs of transport rollers arranged at a predetermined interval on the downstream side of the printing unit and sandwiching and transporting the paper;
A nipping control unit for controlling nipping of the sheet by the conveying roller;
A detection unit that detects an end of the sheet conveyed by the conveyance roller and outputs a detection signal;
A predetermined timing based on the detection signal of the detection unit so that the nipping pressure applied to the trailing edge of the sheet from the conveying roller is smaller than the nipping pressure applied to the portion other than the trailing edge of the sheet from the conveying roller. A control unit for controlling the clamping control unit,
A sheet conveying apparatus comprising: The control unit performs the nipping control before the rear end of the sheet conveyed by the second conveyance roller relatively downstream passes through the first conveyance roller relatively upstream. The sheet conveying apparatus according to claim 1, wherein the nipping pressure of the first conveying roller is decreased by controlling a portion. The said control part controls the said clamping control part based on the output timing of the said detection signal, the size information of the paper to convey, and the conveyance speed of the said conveyance roller, It is characterized by the above-mentioned. Paper transport device.

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