JP2002128359A - Sheet curl correcting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sheet curl correcting method capable of correcting a curl in a sheet generated in a curl uncorrectable range even when the curl uncorrectable range exists close to a rear end part of a sheet. SOLUTION: The sheet 1 held by a carrying roller 2 and a pressure contact roller 3 is carried to a printing means 4 where it is printed. The sheet after it is printed by the printing means 4 is carried to a curl correcting device 7 disposed on the downstream side of the printing means 4 in a sheet carrying direction as an arrow A. As the sheet 1 is pressed by a curl correcting head and a curl correcting platen in the curl correcting device 7, the curl correcting head is moved in a perpendicular direction to the sheet carrying direction. In this action for adding damage to the sheet to correct the curl generated in the sheet, size of damage applied to the sheet is changed to set damage added to the rear end part of the sheet to be larger than the damage added close to the tip part of the sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for correcting the curl of a sheet which can correct the curl generated on the sheet after printing.

[0002]

2. Description of the Related Art A conventional paper transfer curl correction method using a thermal transfer printer will be described. The thermal transfer printer is not shown, but an ink ribbon is arranged between a thermal head and a platen. The paper pressed and held between the transport roller and the pressure roller between the platen is transported by rotating the transport roller. Then, by moving the thermal head down and moving along the platen, the ink of the ink ribbon is thermally transferred to the paper, and one or more lines are printed simultaneously. Or, the sheet is conveyed to the downstream side by an amount corresponding to the printing amount of a plurality of lines at the same time, and the desired image is printed on one sheet of paper 1 by repeatedly printing one line or a plurality of lines at a time. Has become. In such a thermal transfer printer, the thermal head is moved along the platen while being pressed against the paper during printing,
Due to the ironing of the paper or the evaporation of moisture on the paper surface due to the heat generated by the thermal head, the so-called curl, in which the left and right ends in the width direction warp upward with the recording surface inside, on the printed paper. .

A conventional method of correcting the curl of a sheet for correcting the curl is to dispose a curl correcting platen and a curl correcting head on the downstream side of the thermal head in the conveying direction of conveying the sheet, and to connect the thermal head with the platen after printing. The paper discharged from between is pressed and held between the curl correction platen and the curl correction head. Then, the curl correction head is moved along the curl correction platen. Then
By curling the back surface opposite to the printing surface of the paper with the curl correction head, the back surface of the paper is damaged, and the curl generated on the paper 1 after printing is corrected. .

As shown in FIG. 8, a plurality of belt-shaped curl correction marks K which are hard to visually confirm as shown by a two-dot chain line are formed on the paper 1 after the curl correction. The plurality of curl correction marks K are formed at equal intervals of dimension B, for example, corresponding to the printing lines. As shown in FIG. 8, the curl-corrected sheet 1 has a curl-correction-impossible area C having a predetermined size near the rear end 1b.

While the paper 1 is conveyed by the conveyance rollers in the conveyance direction of arrow A, the curl correction impossible area C is repeatedly printed on the paper 1 one or more lines at a time.
When printing of a desired image on a sheet of paper 1 is completed, the rear end portion 1b of the paper 1 is separated from the transport roller and the pressing roller. Then, there is no support for the paper 1 near the rear end 1b, and the paper 1 becomes free. If the curl correction near the rear end 1b of the paper 1 is to be performed in this state, the paper 1 is pulled by the curl correction head pressed against the curl correction platen, and the paper 1 may be broken. The unusable area C cannot be curled. The uncurlable area C has the same dimension as the distance from the rear end portion 1b just before the paper 1 after printing is separated from the transport roller and the pressure roller to the curl correction head.

[0006]

However, the conventional curl correction method cannot correct the curl generated in the curl impossible area C, and as shown in FIG.
The curl is corrected to be flat near a, but there is a problem that a large curl occurs near the rear end 1b where the curl is not corrected. Such a tip 1a
If there is a difference in the curl amount between the shift and the rear end 1b,
When the printed paper 1 is discharged to a paper output tray (not shown), the paper 1 cannot be aligned. Particularly, when a large amount of paper 1 is printed, the paper 1 discharged to the paper output tray is not used. However, there is a problem that it takes time to arrange the paper 1.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and even if there is a curl correction impossible area near the rear end of the sheet, the curl generated in the curl correction impossible area can be corrected. An object is to provide a curl straightening method.

[0008]

According to a first aspect of the present invention, there is provided a method for correcting a curl of a sheet according to the present invention, comprising the steps of: The desired image is printed, and the curl generated on the paper after printing is corrected by transporting the printed paper to a curl correcting unit downstream of the printing unit in the direction in which the paper is transported. In a state in which the curl correction unit is pressed between the curl correction head and the curl correction platen, the curl correction head is moved in a direction perpendicular to the paper conveyance direction to damage the paper, The curl generated in the paper is corrected, and the curl correction is performed by adjusting the magnitude of the damage to be applied to the paper toward the rear end of the paper rather than toward the front end of the paper. It was such a way as to hear.

[0009] A second aspect for solving the above-mentioned problem is as follows.
As the means, the damage to be applied to the sheet at the time of the curl correction may be such that, among the plurality of curl correction marks formed on the sheet by the movement of the curl correction head, the curl correction mark formed near the rear end of the sheet. Was repeatedly pressed with the curl correction head.

[0010] A third aspect for solving the above-mentioned problems is as follows.
As the means, the damage to be applied to the sheet at the time of the curl correction is such that the curl correction marks adjacent to each other formed near the rear end of the paper are corrected by the curl correction marks adjacent to each other formed near the leading end of the paper. The method is such that they are formed closer to each other than the mark or connected to each other with no gap.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The paper curl correcting method of the present invention will be described with reference to a method used in, for example, a thermal transfer printer. 1 to 3 are schematic views for explaining a printing operation by a thermal transfer pudding according to the present invention, FIG. 4 is a view showing an operation of a curl correcting head according to the present invention, and FIG. 5 is a curl correcting head according to the present invention. FIGS. 6 and 7 are schematic views illustrating a curl correcting method according to the present invention.

First, for example, in a thermal transfer printer using the paper curl correcting method of the present invention, a paper 1 of A4 size or the like can be transported along a paper transport path in the transport direction of arrow A shown in FIG. . Further, a transport roller 2 is provided in the sheet transport path on the right side in the drawing, which is the most upstream side in the transport direction of arrow A.
And a press roller 3 that presses against the transport roller 2. The pressing roller 3 is rotatable with the rotation of the transport roller 2. Further, the transport roller 2 and the pressure roller 3 can be pressed against a plurality of locations in the width direction of the sheet 1 (the direction orthogonal to the transport direction of arrow A).

The paper 1 sent from, for example, a paper feed tray (not shown) on the upstream side of the transport roller 2 has its leading end 1a held between the transport roller 2 and the pressure roller 3, and the transport roller 2 With the rotation in the counterclockwise direction, the paper can be conveyed from the upstream side to the downstream side in the conveyance direction of arrow A, that is, the conveyance direction of arrow A. Further, the sheet 1 held between the transport roller 2 and the pressing roller 3 can be returned in the direction of arrow D opposite to the transport direction of arrow A by rotating the transport roller 2 in the clockwise direction. It has become. The operation of returning the sheet 1 in the direction of the arrow D by rotating the transport roller 2 in the reverse direction is performed when the inks of the ink ribbons of different colors, such as color printing, are overprinted.

A printing means 4 capable of printing a desired image on the sheet 1 is provided downstream of the transport roller 2 in the direction of arrow A. The printing means 4 includes a platen 5 and a thermal head 6, and the platen 5
A flat printing surface 5a is formed on a plate-like upper surface. The thermal head 6 is mounted on a carriage (not shown) that can reciprocate along the longitudinal direction of the platen 5 (perpendicular to the paper surface) above the drawing facing the printing surface 4a of the platen 5. It is arranged. The thermal head 6 can be moved toward and away from the platen 5.

A carriage (not shown) has a ribbon cassette (not shown) in which an ink ribbon is wound.
When the ribbon cassette is mounted on the carriage, the ink ribbon is positioned between the platen 5 and the thermal head 6. In addition, between the platen 5 and the thermal head 6, the paper 1 transported by the transport roller 2 together with the ink ribbon is located below the ink ribbon.

Further, a curl correcting means 7 for correcting the curl generated on the paper 1 during printing is provided on the paper transport path on the downstream side of the platen 5 in the transport direction of arrow A. The curl correcting means 7 includes a flat plate-shaped curl correcting platen 8 disposed on the upper side of the sheet transport path, and a curl correcting head 9 which is disposed so as to be able to press against the curl correcting platen 8 and which can move up and down. ing. As shown in FIG. 4, the curl correction platen 8 has a lower surface to which a friction member 8a made of rubber or the like is adhered and attached. Further, as shown in FIGS. 4 and 5, the curl correction head 9 has a base 9a molded from synthetic resin or the like, and a groove is formed in the center of the base 9a. An elastic member 9b made of a coil spring is provided in a central groove of the base 9a.

A pair of rod-shaped guide rollers 9c made of metal such as aluminum are held on a pair of left and right sides below the base 9a shown in FIG. The guide roller 9c is formed to be longer than the width dimension of the base 9a in the front-rear direction, and protrudes by a predetermined size from both side surfaces in the front-rear direction of the base 9a. A belt fixing portion 9d having an uneven tooth ridge is formed below the base 9a.
Is attached to a drive belt 10 described later. A holder 9e made of a synthetic resin or the like is always provided in the groove at the center of the base 9a so as to be elastically urged upward by the action of the elastic member 9b.

At the upper end of the holder 9e, a rod-shaped roller 9f made of metal such as aluminum is rotatably disposed. Both ends of the roller 9f are pivotally supported by the holder 9e with its outer peripheral surface slightly projecting upward from the upper end of the holder 9e. As shown in FIG. 4, such a curl correction head 9 has a belt fixing portion 9d,
It is attached to a drive belt 10 having an uneven tooth ridge on the inner peripheral side. The drive belt 10 has a drive pinion gear 11 on one side and a rotatable idle gear 1 on the other side.
By rotating a drive source such as a stepping motor (not shown) that is stretched around the pinion 2 and rotating the pinion gear 11 forward or backward, the curl straightening head 9 moves in the directions of arrows E and F, ie, the curl straightening. It is reciprocable along the platen 8.

The curl correction head 9 shown in FIG.
A guide roller 9c projecting from the base 9a is guided by a pair of guide rails 13 formed on a printer main body (not shown), and is movable in the directions of arrows E and F. When the curl correction head 9 is moved, for example, in the direction of arrow F, the guide roller 9c is positioned on the upper surface of the guide rail 13, and the uppermost roller 9f is positioned on the curl correction platen 8.
It can be moved in a state of being pressed against.

When the movement of the curl correction head 9 in the direction of arrow F moves to the end, the guide roller 9c is disengaged from the guide rail 13 and descends below the guide rail 13. When the curl correction head 9 is moved in the direction of the arrow E in this state, the guide roller 9c is located on the lower surface of the guide rail 13, and the roller 9f moves away from the curl correction platen 8 in a non-pressing state. . The guide roller 9c
Is positioned on the upper surface or the lower surface of the guide rail 13 by a cam mechanism (not shown) so that the curl correction head 9 is raised and lowered.

A rotatable paper discharge roller 14 and a paper discharge abutting above the paper discharge roller 14 are provided on the paper transport path on the downstream side of the curl correcting means 7 in the direction of arrow A shown in FIG. A guide 15 is provided, and the curl-corrected sheet 1 conveyed in the direction of arrow A can be discharged to, for example, a discharge tray (not shown). In the thermal transfer printer having such a configuration, the paper 1 and the ink ribbon (not shown) are positioned on the platen 5, and a plurality of heating elements (not shown) of the thermal head 6 pressed down to the platen 5 with the head down. ) Is moved along the platen 5 while selectively generating heat based on the print information, whereby desired characters or images can be printed on the paper 1 one or more lines at a time.

In the paper curl correcting method of the present invention used in such a thermal transfer printer, the printing head 4 raises the thermal head 6 every time one or more lines are printed simultaneously by the printing means 4. The conveying roller 2 is rotated to convey the next line position to be printed. At this time, as shown in FIG. 1, the curl forcing means 7 is in a non-pressing state in which the roller 9f of the curl correction head 9 is separated from the curl correction platen 8, and the leading end 1a of the paper 1 can be transported. I have. Then, the leading end portion 1a of the paper 1 after printing
Is passed between the curl correction head 9 and the curl correction platen 8 in a non-pressed state, and is sandwiched between the paper discharge roller 8 and the paper discharge guide 9.

In this state, the curl straightening head 9 is raised, and as shown in FIG.
To press against the curl straightening platen 8. Next, the curl correction head 9 is moved in the direction of arrow F shown in FIG.
When the back side of the paper 1 is squeezed by the curl correction head 9, the back side of the paper 1 is damaged, and
The curl that has occurred can be corrected. Each time printing of one or more lines is completed,
Is transported in the transport direction of arrow A by the transport roller 2, and each time the paper 1 is damaged by the curl correcting means 7 to perform the above-described curl correction by the curl correcting means 7, thereby achieving the conventional curl as shown in FIG. As described in the technology, a plurality of curl correction marks K which are difficult to visually confirm are formed.

However, the uncurled area C is formed on the sheet 1 after the curl correction as described in the background art. The curl correction impossible area C will be described again with reference to FIG. 3. When printing of a desired image on one sheet 1 is completed, the rear end 1b of the sheet 1
Get off. At this time, the dimension from the rear end 1b of the sheet 1 to the curl correction head 9 becomes the same as the dimension of the curl correction impossible area C. That is, the dimension of the curl correction impossible area C is the same as the dimension G from the transport roller 2 to the curl correction head 9 shown in FIG.

When the trailing edge 1b of the sheet 1 comes off the conveying roller 2 and the pressing roller 3, the printing on the sheet 1 has been completed. There is no supporting member near the rear end 1b, and the rear end 1b is free. Even if the curl correction is performed by pressing the curl correction platen 8 and the curl correction head 9 against the rear end 1b of the paper 1 in the free state, the curl correction is performed on the rear end 1b of the paper 1 in the free state. There was a risk of being pulled by the head 9 and breaking. For this purpose, the printed paper 1 has a rear end 1b.
The curl cannot be corrected in the curl correction impossible area C, and the curl amount of the sheet 1 after the curl correction is larger at the rear end 1b than at the front end 1a.

In order to eliminate the uncurlable area C, the curl correction may be performed by lowering the thermal head 6 to eliminate the free state near the rear end 1b. It has a plurality of heating elements (not shown) formed in rows in the left-right direction of FIG.
Although a part of the sheet 1 in the width direction can be pressed by the heating element, a plurality of portions in the width direction of the sheet 1 cannot be pressed at the same time like the conveying roller 2 and the pressing roller 3. For this reason, the portion where the heating element is not pressed against may be pulled and broken when it is squeezed by the curl correction head 9.

The curl correcting method for paper according to the present invention comprises the following steps:
In the operation for correcting the curl that has occurred, the curl correction head 9 presses and moves the curl correction mark K formed on the paper 1 to form a curl correction impossible area C near the rear end 1 b of the paper 1. The curl correction marks are repeatedly pressed by the curl correction head 9 to form a curl correction mark K1 as shown by hatching in FIG. By repeatedly pressing the curl correction marks near the curl correction impossible area C, the paper 1
The damage applied to the rear end portion 1b can be greater than that of the front end portion 1a.

Therefore, even if the curl correction head 9 cannot be pressed directly against the curl correction impossible area C, the curl correction method of the present invention eliminates the curl of the sheet 1 generated in the curl correction impossible area C. Or smaller. That is, in the operation of correcting the curl generated in the paper 1 by damaging the paper 1, the magnitude of the damage applied to the paper 1 is reduced in the vicinity of the curl correction impossible area C rather than near the leading end 1 a of the paper 1. Is larger at the rear end 1b.

As a modification of the present invention in which the magnitude of the damage to be applied to the paper 1 is varied, as shown in FIG. 7, adjacent curls formed near the rear end 1b of the paper 1 when the curl is corrected. The correction marks K may be formed closer to each other than the gap dimension B adjacent to each other formed near the distal end portion 1a, or may be connected to each other without any clearance to form a wide curl correction mark K2. As a result, the magnitude of damage to be applied to the sheet 1 can be larger at the rear end 1b than at the front end 1a, and the curl in the curl correction impossible area C can be eliminated or reduced. .

[0030]

According to the method for correcting the curl of a sheet of the present invention, the amount of damage to be applied to the sheet is made larger at the rear end of the sheet than at the front end of the sheet. It is possible to eliminate or reduce the curl generated in the near curl correction impossible area, and the paper discharged to the paper discharge tray after printing is good.

In the operation of correcting the curl generated on the sheet, the curl correction mark formed on the sheet near the rear end portion of the plurality of curl correction marks formed on the sheet by the movement of the curl correction head. Since the marks are repeatedly pressed against the curl correction head, the damage to be applied to the paper can be larger at the rear end than at the front end,
The curl generated in the curl uncorrectable region can be eliminated or reduced. In addition, since the intervals between the curl correction marks can be made equal, the amount of paper feeding after printing one or more lines on the paper at the same time can be always constant, and the rotation control of the transport roller can be easily performed. Can be simplified.

Further, the curl correction marks adjacent to each other formed near the rear end of the sheet are connected to each other with a gap closer to the curl correction marks adjacent to each other formed near the leading end of the sheet, or the gap is eliminated. Damage to the paper can be greater at the trailing edge than at the leading edge.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a printing operation by a thermal transfer pudding according to the present invention.

FIG. 2 is a schematic diagram illustrating a printing operation by a thermal transfer pudding according to the present invention.

FIG. 3 is a schematic diagram illustrating a printing operation by a thermal transfer pudding according to the present invention.

FIG. 4 is a view showing the operation of the curl correction head according to the present invention.

FIG. 5 is a perspective view of a curl correction head according to the present invention.

FIG. 6 is a schematic diagram illustrating a method for straightening a sheet according to the present invention.

FIG. 7 is a schematic view illustrating a method for straightening a sheet according to the present invention.

FIG. 8 is a schematic diagram illustrating a conventional paper sheet curl correction method.

FIG. 9 is a perspective view illustrating the state of curl when the curl is corrected by the conventional paper curl correcting method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 paper 1a leading end 1b trailing end 2 transport roller 3 pressure roller 4 printing means 5 platen 5a printing surface 6 thermal head 7 curl correcting means 8 curl correcting platen 9 curl correcting head 9f roller 10 drive belt 11 pinion gear 12 idle gear 13 Guide rail 14 Discharge roller 15 Discharge guide

Claims (3)

[Claims] 1. A desired image is printed on a sheet conveyed to a printing unit while being held between a conveying roller and a pressing roller, and the curl generated on the sheet after printing is corrected in a direction in which the sheet is conveyed. The paper after printing is conveyed to the curl correcting means on the downstream side of the printing means, and the paper is pressed against the curl correcting head of the curl correcting means and the curl correcting platen. The paper is damaged by moving the paper in a direction perpendicular to the transport direction of the paper, and the curl generated on the paper is corrected.The curl correction corrects the magnitude of the damage applied to the paper by changing the size of the paper. A curl correction method for a sheet, characterized in that a portion closer to the rear end of the sheet is made larger than a portion closer to the front end of the sheet. 2. The method according to claim 1, wherein the damage to the sheet at the time of the curl correction is caused by the curl formed at a position closer to a rear end of the sheet among a plurality of curl correction marks formed on the sheet by the movement of the curl correction head. 2. The method according to claim 1, wherein the correction mark is repeatedly pressed by the curl correction head. 3. The method according to claim 1, wherein the damage applied to the sheet at the time of the curl correction is such that the curl correction marks adjacent to each other formed near the rear end of the paper are replaced with the curls adjacent to each other formed near the leading end of the paper. 3. The paper curl correcting method according to claim 2, wherein the curls are formed closer to each other than the correction marks or without any gaps and connected to each other.