JP2007197123A - Recording paper curl correction mechanism, image forming device, and recording paper curl correction method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct a curl formed on a recording paper such as a rolled paper by a compact mechanism efficiently and prevent deterioration of quality of the recording paper after correcting the curl. <P>SOLUTION: This recording paper curl correction mechanism provided with a thermal head 10 and being applicable to a thermal printer 1 for printing image on a rolled paper 41 is provided with a decurl roller 17 capable of bending the rolled paper 41 in the reverse direction to the direction of curl of the rolled paper 41. The decurl roller 17 is arranged at a position which is on the downstream side of the thermal head 10 and at which remaining heat generated upon image printing by the thermal head 10 remains on the rolled paper 41. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a recording paper curl correction mechanism for correcting curl attached to recording paper, an image forming apparatus including such a recording paper curl correction mechanism, and a recording paper curl correction method. The present invention relates to a recording paper curl correction mechanism, an image forming apparatus, and a recording paper curl correction method that enable efficient curl correction and can make the state of the recording paper constant at the time of paper discharge.

  Conventionally, image forming apparatuses such as thermal printers include a type that uses cut paper as a recording paper and a type that uses roll paper. In recent years, with the spread of digital cameras, roll paper, which is advantageous in terms of cost for printing with high image quality, has been widely used. This roll paper is obtained by winding a long recording paper into a cylindrical shape around a paper tube as a winding core, and unwinds and feeds a necessary amount of recording paper each time printing is performed, and after printing is completed The paper is cut into the size of the paper and discharged.

FIG. 8 is a perspective view showing the internal structure of such a conventional thermal printer 100.
As shown in FIG. 8, a thermal head 110 having a plurality of heating elements (for example, heating resistors) is installed inside the thermal printer 100. A platen roller 111 is disposed at a position facing the thermal head 110.

  Further, an ink ribbon 31 (not shown) is sandwiched between the thermal head 110 and the platen roller 111. The ink ribbon 31 includes a plurality of different color inks (for example, yellow (Y), magenta (M), and cyan (C) inks) and a transparent laminate ink (L) in a direction perpendicular to the unwinding direction. Are arranged repeatedly on the base film sequentially.

  Furthermore, a roll paper 41 is held by a paper holder 42 inside the thermal printer 100. The unrolled roll paper 41 passes between transport rollers (capstan roller 112 and pinch roller 113) provided upstream of the platen roller 111 with respect to the feed direction of the roll paper 41, and then the thermal head. 110 and the platen roller 111 are cut by a cutter 118 and then discharged.

FIG. 9 is a flowchart showing a printing operation by the conventional thermal printer 100 shown in FIG.
As shown in FIG. 9, the roll paper 41 is fed in the first step S101 after the start of the printing operation. When a print command is issued in the next step S102, yellow (Y) of the ink ribbon 31 is printed in the next steps S103 to S104.

  That is, in step S103, the capstan roller 112 (see FIG. 8) is driven to rotate counterclockwise, and the leading end of the roll paper 41 is fed to the tip of the thermal head 110 (see FIG. 8). The printing start point and the heating element of the thermal head 110 are opposed to each other. Thereafter, the thermal head 110 that has been raised is lowered, and the ink ribbon 31 and the roll paper 41 are sandwiched between the heating element of the thermal head 110 and the platen roller 111 (see FIG. 8).

  In the subsequent step S104, the capstan roller 112 is driven to rotate backward in the clockwise direction, and the roll paper 41 is returned to the tip of the roll paper 41 in the reverse direction to step S103. Further, the ink ribbon 31 is wound up in the same direction and at the same speed as the roll paper 41. At the same time, the heating elements arranged on the thermal head 110 are selectively energized to apply thermal energy from the heating elements to the ink ribbon 31, and yellow (Y) from the printing start point of the roll paper 41 to the printing end point. ) Color ink is printed.

  Therefore, in the case of the conventional thermal printer 100 shown in FIG. 8, the roll paper 41 is sent to the printing start point in step S103, and printing is performed while returning the roll paper 41 in step S104. ), The roll paper 41 is reciprocated once by feeding and returning the roll paper 41.

  Similarly, in step S105, the roll paper 41 is sent to the printing start point, and in step S106, magenta (M) of the ink ribbon 31 is printed while the roll paper 41 is returned, so that yellow (Y) printing is included. So far, the roll paper 41 reciprocates twice. Furthermore, the roll paper 41 is sent to the printing start point in step S107, and cyan (C) of the ink ribbon 31 is printed while returning the roll paper 41 in step S108. This is the third reciprocation of the roll paper 41. Furthermore, the roll paper 41 is sent to the printing start point in step S109, and the laminate ink (L) of the ink ribbon 31 is transferred while returning the roll paper 41 in step S110. This is the fourth reciprocation of the roll paper 41.

  As described above, in the conventional thermal printer 100 shown in FIG. 8, the roll paper 41 needs to be reciprocated four times in order to print the color ink (Y, M, C) and transfer the laminate ink (L). Further, as described above, the transfer of the laminate ink (L) is performed while returning the roll paper 41. Therefore, in order to cut and discharge the roll paper 41 after printing, the roll paper is printed in the next step S111. It is necessary to send the 41 printing end point to the position of the cutter 118 (see FIG. 8). Then, the roll paper 41 is reciprocated four and a half times, and then the roll paper 41 is cut and discharged in the final step S112, and the printing operation is completed.

  As a result, in the conventional thermal printer 100, the roll paper 41 is reciprocated four and a half times including the feeding of the roll paper 41 after the end of printing, from the start to the end of the printing operation. Here, since the roll paper 41 is obtained by winding a recording paper in a cylindrical shape in advance, the roll paper 41 that has been unrolled is curled. The curl is not naturally corrected even when the roll paper 41 is reciprocated four and a half times, and becomes noticeable as the roll paper 41 is consumed, that is, as the roll paper 41 approaches the end of winding. It will be a thing.

  Therefore, when printing is performed on the unrolled roll paper 41, and the sheet is cut and discharged as it is, the roll paper 41 is curled with the recording surface convex as shown in FIG. The resulting image looks distorted or cannot be properly stacked and ejected, which makes it difficult to see the ejected state. Moreover, such a situation gradually gets worse and the curl will not disappear.

  Therefore, various techniques for correcting the curl of the roll paper 41 are disclosed. That is, a curl correction method is known in which a part of the roll paper 41 is mechanically pressed in the conveyance path of the unrolled roll paper 41, and the roll paper 41 is simply bent in a direction opposite to the curl direction. . This curl correcting method is a method in which a curl correcting means such as a decurling roller is brought into contact with the roll paper 41, and is configured such that the decurling roller can be moved and retracted.

  As a technique for correcting the curl, a method of heating one side of the roll paper 41 and correcting using the difference in heat shrinkage between the front and back is also known. In this curl correction method, the roll paper 41 is heated using a heating means, and a heating element such as a plate heater or a halogen heater is used as the heating means.

For example, Patent Document 1 discloses a thermal printer that changes a discharge direction by bringing a printed roll paper into contact with a curl correction member. According to the technique described in Patent Document 1, since the curl correction effect can be changed by the roll outer diameter detection lever, the curl that becomes stronger as the roll outer diameter decreases can be corrected. .
Japanese Patent No. 3491524

Patent Document 2 discloses a curl correction method having a curl correction head that presses a roll paper to cause damage. The curl correction head is configured to reciprocate at right angles to the direction in which the roll paper is conveyed so as to squeeze the back surface of the roll paper.
JP 2002-128360 A

Furthermore, Patent Document 3 discloses a thermal printer that detects the remaining amount of roll paper, moves the feed roller upward when the remaining amount is low, and applies a tension that curves the roll paper in the reverse direction. ing.
JP 2004-223715 A

Further, Patent Document 4 discloses a thermal printer that includes a curl correcting thermal head that heats the back surface of the roll paper and corrects the curvature of the roll paper by curving the roll paper in the opposite direction.
JP 2000-318194 A

Further, Patent Document 5 discloses a curl correction that includes curl correction means for bending the roll paper in a direction opposite to the curl and heating means (heater) for heating the bent roll paper in the conveyance path. An apparatus is disclosed.
Japanese Patent Laid-Open No. 60-2559

  Here, all of the techniques described in Patent Document 1 to Patent Document 5 provide a mechanical curl correcting means or a heating means to separately correct the curl in the roll paper conveyance path.

  However, in recent years, the material, thickness, standard size, and the like of roll paper have been diversified, and accordingly, the strength of curl formed on the roll paper has become widespread. Therefore, it is necessary to expand the curl correction range according to the strength of the curl, and if the mechanical curl correction means is used, the amount of movement of the curl correction means must be increased, and the apparatus is large. To increase parts cost and manufacturing cost. Further, even if the heating means is provided to correct the curl, the apparatus becomes larger due to the addition or enhancement of the heating means, and the parts cost and manufacturing cost increase. Furthermore, the mechanical damage and thermal damage that the roll paper receives increases, which causes problems in terms of quality such as durability.

  Therefore, the problem to be solved by the present invention is that when correcting curl attached to recording paper such as roll paper, the curl can be corrected efficiently with a compact mechanism, and the recording after the curl is corrected It is to be able to suppress paper quality deterioration.

The present invention solves the above-described problems by the following means.
The invention according to claim 1, which is one of the present invention, is used in an image forming apparatus in which heat is transmitted from a heat source to the recording paper when printing is performed while the recording paper is conveyed. A recording paper curl correction mechanism for correcting attached curl, comprising curl correction means capable of bending the recording paper in a direction opposite to the curl direction of the recording paper, wherein the curl correction means is a paper feed The recording paper is disposed downstream of the heat source with respect to the recording paper feeding direction from the side toward the paper discharge side, and at a position where residual heat at the time of printing by the heat source remains on the recording paper. Features.

(Function)
The invention according to claim 1 includes a curl correcting means capable of bending the recording paper in a direction opposite to the curling direction of the recording paper. Therefore, the curl can be corrected by bending the recording paper in the direction opposite to the curl direction by the curl correcting means. Further, the curl correcting means is arranged at a position downstream of the heat source with respect to the recording paper feeding direction from the paper supply side to the paper discharge side, and at a position where residual heat at the time of printing by the heat source remains on the recording paper. Has been. Therefore, the same effect as that obtained when the curling is corrected by heating can be obtained, and the curling of the recording paper can be reliably corrected while minimizing mechanical and thermal damage to the recording paper.

  According to the above invention, the recording paper is bent in the direction opposite to the direction of the curl attached to the recording paper while utilizing the residual heat remaining on the recording paper at the time of printing. Therefore, the curl can be corrected efficiently with a compact mechanism. Further, the state of the recording paper at the time of paper discharge can be made constant, and the quality deterioration of the curled correction recording paper can be suppressed.

Embodiments of the present invention will be described below with reference to the drawings. In the following embodiment, a thermal printer 1 is taken as an example of the image forming apparatus of the present invention. The recording paper curl correction mechanism of the present invention is mounted on the thermal printer 1.
FIG. 1 is a perspective view showing a thermal printer 1 of the present embodiment.
As shown in FIG. 1, the thermal printer 1 includes a housing part 2 and a door part 3 attached to the front surface of the housing part 2. A paper discharge port 8 is formed in the lower part of the door portion 3, and a paper discharge tray 9 is attached to the paper discharge port 8.

  Here, a power switch 4 is provided on the front side of the housing 2. In addition, an interface unit 5 including a plurality of connectors for external connection is disposed on the rear surface side of the housing unit 2. The interface unit 5 can acquire image information and the like from a computer. Note that various recording media such as a magnetic disk, an optical disk, and a memory card can be connected to the interface unit 5 to read image information and the like without using a computer.

  On the other hand, on the upper part of the door part 3, an operation panel 6 for setting a print or the like with the thermal printer 1 is provided. Information acquired from the interface unit 5, input or selected from the operation panel 6, various other messages, and the like are displayed on the liquid crystal panel 7.

FIG. 2 is a perspective view showing a state in which the door portion 3 of the thermal printer 1 of the present embodiment shown in FIG. 1 is opened. The ink cassette 30 is taken out and illustrated. The outer shape of the ink cassette 30 is indicated by a dotted line so that the internal structure becomes clear.
As shown in FIG. 2, a thermal head 10 is installed on the back side of the door portion 3. On the other hand, a platen roller 11 (corresponding to a platen in the present invention) is disposed in the housing 2 at a position facing the thermal head 10 when the door 3 is closed.

  In addition, a reel driving unit 14 a for rotating the supply reel 32 of the ink cassette 30 is provided above the platen roller 11 in the housing unit 2. Further, below the platen roller 11, reel drive means 14b for rotating the take-up reel 33 of the ink cassette 30 is provided.

  When the ink cassette 30 is attached to the casing 2, the ink ribbon 31 is disposed so as to pass over the platen roller 11. Further, when the door portion 3 is closed, the ink ribbon 31 is disposed between the thermal head 10 and the platen roller 11. In this state, when the reel driving unit 14 b is driven to rotate, the ink ribbon 31 is taken up by the take-up reel 33.

FIG. 3 is a plan view showing the ink ribbon 31 used in the thermal printer 1 of the present embodiment shown in FIG.
As shown in FIG. 3, the ink ribbon 31 is wound between a supply reel 32 and a take-up reel 33 provided in the ink cassette 30 (see FIG. 2). Yellow (Y), magenta (M), and cyan (C) color inks (sublimation dyes) and a transparent laminating ink (L) are sequentially and repeatedly applied on the belt-shaped resin film in a direction perpendicular to each other. It becomes the composition. The laminate ink (L) is laminated on a recording image formed by each color ink (Y, M, C), thereby protecting the recording image from ultraviolet rays and improving light resistance. .

FIG. 4 is a side view showing an outline of the internal configuration of the thermal printer 1 of the present embodiment shown in FIG.
As shown in FIG. 4, a roll paper 41 (a recording paper wound in a cylindrical shape in the present invention) is held by a paper holder 42 inside the housing portion 2 shown in FIG. 1. If necessary, the roll paper 41 unwound by the pair of paper feed rollers 14 is upstream of the thermal head 10 and the platen roller 11 with respect to the feed direction of the roll paper 41 (left direction in FIG. 4). After passing between the capstan roller 12 (driving roller) and the pinch roller 13 (driven roller) provided on the platen, passing between the thermal head 10 and the platen roller 11, the paper is cut by the cutter 18 and discharged. It has become so.

  Here, the capstan roller 12 and the pinch roller 13 correspond to the conveying roller in the present invention, and the roll paper 41 is fed in the feeding direction and the direction by rotating the capstan roller 12 forward and backward as necessary. It can be transported in the return direction. Further, in the thermal printer 1 of the present embodiment, the platen roller 11 is also rotationally driven so that the roll paper 41 can be conveyed in the feeding direction.

  The roll paper 41 is conveyed in the feeding direction by the cooperation of the capstan roller 12 and the platen roller 11. At that time, a torque limiter is attached to the drive mechanism of the platen roller 11 and the peripheral speed when the platen roller 11 is freely rotated is set higher than the peripheral speed when the capstan roller 12 is freely rotated. When the roll paper 41 is conveyed in the feeding direction, a tension is always applied to the roll paper 41 between the capstan roller 12 and the platen roller 11. Therefore, the roll paper 41 is not slackened, and conveyance troubles such as buckling are prevented, and a reliable printing operation can be obtained.

  In addition, a pair of conveyance guides 15 are provided between the conveyance rollers (the capstan roller 12 and the pinch roller 13) and the platen roller 11 to regulate the positions of the front surface side (recording surface side) and the rear surface side of the roll paper 41. Has been. A part of the conveyance guide 15 is formed in a shape parallel to a tangent line connecting the capstan roller 12 and the platen roller 11, and guides the conveyed roll paper 41 onto the platen roller 11. Yes. For this reason, in addition to the cooperation of the capstan roller 12 and the platen roller 11, there is a position restriction by the conveyance guide 15, so that the roll paper 41 may be affected by load fluctuations during printing, or the leading end may be The sheet is reliably transported between the thermal head 10 and the platen roller 11 without colliding with the platen roller 11 and buckling.

  On the other hand, the ink ribbon 31 is unwound from the supply reel 32 in accordance with the gradation data subjected to the color conversion process, is guided to the two guide rollers 19, and is wound on the take-up reel 33. Therefore, when the thermal head 10 is lowered, the ink ribbon 31 and the roll paper 41 are sandwiched between the thermal head 10 and the platen roller 11, and the thermal head 10 is attached to the surface of the roll paper 41 via the ink ribbon 31. The side (recording surface side) is pressed.

  In the thermal head 10, a plurality of heating resistors (corresponding to heating elements in the present invention) are arranged in a line in the width direction (line direction) of the roll paper 41. When the roll paper 41 and the ink ribbon 31 are transported in the feed direction, the heating resistor of the thermal head 10 is selectively energized and applied to the ink ribbon 31 using the heat energy generated thereby. Each color ink (Y, M, C) is transferred to the recording surface of the roll paper 41. Further, similarly, the laminate ink (L) of the ink ribbon 31 is laminated on the recorded image.

  Further, the ink ribbon 31 that is superimposed on the roll paper 41 between the thermal head 10 and the platen roller 11 and to which the ink is transferred is then transferred from the thermal head 10 and the platen roller 11 in the feed direction of the roll paper 41. Is also peeled off from the roll paper 41 by the ribbon peeling member 16 provided on the downstream side, and taken up on the take-up reel 33.

  The ribbon peeling member 16 is a guide member for changing the transport direction of the ink ribbon 31 at a steep angle. That is, the ink ribbon 31 is strongly attached to the roll paper 41 by the pressing force and heat of the thermal head 10 when the ink transfer is completed. Therefore, the tip of the blade-shaped ribbon peeling member 16 is brought into contact with the ink ribbon 31 and the ink ribbon 31 is pulled away from the roll paper 41 at a predetermined angle with respect to the transport direction of the roll paper 41, whereby the ink ribbon 31 is removed from the roll paper 41. It is made to peel.

  On the other hand, the roll paper 41 after printing is bent in the direction opposite to the direction of the curl applied to the roll paper 41 (upward in FIG. 4) by the decurling roller 17 (corresponding to the curl correcting means in the present invention). The curl is corrected. Thereafter, the roll paper 41 is cut into a predetermined size by the cutter 18 and discharged.

FIG. 5 is a flowchart showing the printing operation by the thermal printer 1 of the present embodiment shown in FIG.
6 and 7 are side views showing the peripheral portion of the thermal head 10 shown in FIG. 4, and FIG. 6 shows the states of steps S3, S5, and S7 in the flowchart shown in FIG. FIG. 7 shows the state of step S10 in the flowchart shown in FIG.

  As shown in FIG. 5, in the first step S1 after the start of the printing operation, the paper feed roller 14 (see FIG. 4) is rotationally driven to unwind and feed the roll paper 41. When a print command is issued in step S2, yellow (Y) of the ink ribbon 31 (see FIG. 3) is printed in the next step S3. Normally, since the roll paper 41 has already been fed and is in a standby state on the platen roller 11 (see FIG. 4), the printing in step S3 is performed by the printing command in step S2 without passing through step S1. Is executed.

  In step S 3, the capstan roller 12 shown in FIG. 6 is driven to rotate counterclockwise, and the roll paper 41 sandwiched between the pinch roller 13 is sent to the platen roller 11 through the conveyance guide 15. The platen roller 11 is also driven to rotate counterclockwise. At this time, when a sensor (not shown) detects the leading end (starting point of printing) of the roll paper 41, the number of steps of a motor (not shown) that drives the platen roller 11 is counted, and the count number is a predetermined number. When the number of steps is reached, the heating resistor of the thermal head 10 is energized. Thereafter, the thermal head 10 that has been raised is lowered, and the ink ribbon 31 and the roll paper 41 are sandwiched between the heating resistor of the thermal head 10 and the platen roller 11.

  In this state, the platen roller 11 and the capstan roller 12 cooperate to rotate the platen roller 11 and the capstan roller 12 counterclockwise so that the roll paper 41 from the paper supply side to the paper discharge side The roll paper 41 is fed in the feeding direction (left direction in FIG. 6). Then, the tension is applied to the roll paper 41 and the position of the roll paper 41 is regulated by the conveyance guide 15, and the roll paper 41 is sandwiched between the thermal head 10 and the platen roller 11 and the printing is finished from the printing start point. It is smoothly transported to the point in the feed direction.

  As the roll paper 41 is transported, the take-up reel 33 (see FIG. 4) is driven to rotate counterclockwise, and the ink ribbon 31 is taken up in the same direction and at the same speed as the roll paper 41. Then, the yellow (Y) color ink of the ink ribbon 31 is sequentially rolled from the front end portion (starting point of printing) of the roll paper 41 by the heat energy applied to the ink ribbon 31 from the heating resistor of the thermal head 10. 41 is transferred.

  At this time, as described above, in the thermal head 10, the heating resistor is energized and driven before the roll paper 41 is sandwiched, and at that time, the tip of the roll paper 41 (starting point of printing) Since it is immediately before the portion sandwiched between the head 10 and the platen roller 11, the transfer is executed just before the roll paper 41 is sandwiched. Therefore, the thermal printer 1 according to the present embodiment can print yellow (Y) from the start point of printing to the end point of printing without forming any margin at the leading end of the roll paper 41. During printing of each color ink (Y, M, C), as shown in FIG. 6, the decurling roller 17 is in the retracted position and the roll paper 41 is not bent.

  After printing yellow (Y) in this way, in the next step S4, preparation is made for printing magenta (M) in the next step S5. That is, in the case of color printing, since the transfer of color ink is executed for each color, whenever the color to be transferred is changed, the lowered thermal head 10 is raised and the roll paper 41 is pressed by the thermal head 10. After the release, the roll paper 41 is returned to the start point of printing by driving the capstan roller 12 to rotate counterclockwise. The platen roller 11 incorporates a one-way clutch (not shown) between the rotating shaft and the motor, and the platen roller 11 is driven to rotate as the roll paper 41 is returned. In addition, no extra load acts on the roll paper 41.

  Therefore, in the case of the thermal printer 1 of the present embodiment, printing is performed to the printing end point while feeding the roll paper 41 in the feeding direction (leftward in FIG. 6) from the paper feeding side to the paper ejection side in step S3. Thereafter, since the roll paper 41 is returned to the printing start point in step S4, the roll paper 41 reciprocates once by feeding and returning the roll paper 41 for yellow (Y) printing of the ink ribbon 31. .

  In the next step S5, as in step S3, magenta (M) printing of the ink ribbon 31 is performed while feeding the roll paper 41 to the printing end point. In step S6, printing is performed in the same manner as in step S4. Return the roll paper 41 to the start point. Therefore, the magenta (M) print is the second reciprocation of the roll paper 41. Further, cyan (C) printing of the ink ribbon 31 is performed while feeding the roll paper 41 to the printing end point in step S7, and the roll paper 41 is returned to the printing starting point in step S8, so cyan (C) printing is performed. Is the third reciprocation of the roll paper 41.

  Further, in step S9 and step S11, the laminate ink (L) of the ink ribbon 31 is transferred while feeding the roll paper 41 to the end point of printing. Since this laminate ink (L) is the ink that is finally transferred to the roll paper 41, it is not necessary to return the roll paper 41 that is necessary for transferring the next ink. That is, for the transfer of the laminate ink (L), after the roll paper 41 is sent in the feed direction to the end point of printing, the roll paper 41 is returned by continuing to transport the roll paper 41 in the feed direction. Instead, the roll paper 41 can be cut and discharged at the printing end point.

  As described above, in the thermal printer 1 of the present embodiment, the roll paper 41 needs to be reciprocated three times in order to print the color ink (Y, M, C), but the last laminate ink (L) is transferred. When the paper is discharged, the roll paper 41 does not need to be returned. Therefore, since the roll paper 41 has only to be reciprocated halfway between the start and end of the printing operation, the present embodiment is more effective than the conventional thermal printer 100 (see FIGS. 8 and 9) that needs to reciprocate four and a half times. The thermal printer 1 according to the embodiment can shorten the printing time by one reciprocation of the roll paper 41.

  Further, in the thermal printer 1 of the present embodiment, immediately after step S9 (start of printing) for transferring the laminate ink (L), in step S10, as shown in FIG. The roller 17 abuts, and the curl attached to the roll paper 41 is corrected by bending the roll paper 41 upward.

  The decurling roller 17 is a metal roller that rotates in contact with the roll paper 41 being conveyed, and the center of rotation is supported by the support arm 20. One end of the support arm 20 uses the rotation shaft of the platen roller 11 as a swing fulcrum, and a decal roller 17 is attached to the free end on the other end side. Therefore, the decurling roller 17 swings around the platen roller 11 around the rotation axis of the platen roller 11 and can move so as to contact or separate from the roll paper 41.

  Here, in order to bring the decurling roller 17 in the retracted position shown in FIG. 6 into contact with the roll paper 41, the cam 22 is rotated counterclockwise from the state of FIG. 6 to the state of FIG. The cam follower 21 is lifted. Then, the decurling roller 17 rises and comes into contact with the back side of the roll paper 41. Until step S9, as shown in FIG. 6, the cam 22 is separated from the cam follower 21, and the decurling roller 17 is in the retracted position and is not in contact with the roll paper 41. However, in step S10, the roll paper 41 As shown in FIG. 7, the curl of the roll paper 41 is corrected by rotating the cam 22 around the end of the ribbon peeling member 16 and bringing the decurling roller 17 into contact with the back side of the roll paper 41. .

  That is, as shown in FIG. 4, the roll paper 41 is wound with the recording surface on the front side, and has a curled wrinkle with a convex surface side (recording surface side). Therefore, if the roll paper 41 having the laminate ink (L) transferred to the recording surface is ejected as it is in step S9, the convex curl on the front side remains. Therefore, in step S10, as shown in FIG. 7, in order to bend the roll paper 41 in the direction opposite to the direction of the curl attached to the roll paper 41 (the direction in which the surface side is concave and upward in FIG. 7). The decurling roller 17 is brought into contact with the back side of the roll paper 41.

  In addition, the decurling roller 17 is disposed immediately after the ribbon peeling member 16 on the downstream side of the platen roller 11 in the feeding direction of the roll paper 41 (left direction in FIG. 7). In other words, the decurling roller 17 is disposed in the vicinity of the thermal head 10 by utilizing the space on the downstream side of the platen roller 11 vacated by disposing the capstan roller 12 on the upstream side of the platen roller 11. For this reason, at the position where the decurling roller 17 contacts the roll paper 41, the residual heat from the transfer of the laminate ink (L) by the thermal head 10 remains on the roll paper 41.

  When the decurling roller 17 is brought into contact with the back side of the roll paper 41 in the residual heat remaining state and the roll paper 41 is bent in a direction opposite to the curl direction (upward in FIG. 7), the substances constituting the roll paper 41 are changed. The roll paper 41 is deformed before heat shrinkage or moisture evaporation is completed, and the same effect as that obtained when the curling is corrected by heating is obtained. Therefore, the curl of the roll paper 41 can be reliably corrected. Further, curling can be corrected efficiently without installing a heating means such as a heater.

  By the way, the degree of curling applied to the roll paper 41 varies depending on the environmental conditions (temperature, humidity, etc.) at the time of printing, the material of the roll paper 41, the conveyance speed of the roll paper 41, the roll outer diameter of the roll paper 41, and the like. . Therefore, in the thermal printer 1 of this embodiment, the degree of curling of the roll paper 41 is changed according to the degree of curling applied to the roll paper 41 so that the amount of curl correction can be adjusted. Specifically, as shown in FIG. 7, since the surface of the cam 22 is inclined, the rotation of the cam 22 is based on the environmental conditions at the time of printing, the material of the roll paper 41, the conveyance speed, the outer diameter of the roll, and the like. By adjusting the angle, the degree to which the cam 22 lifts the cam follower 21 can be changed steplessly.

  For example, the curl shape and degree of the roll paper 41 gradually change from the start of winding to the end of winding, and the curl becomes conspicuous as it approaches the end of winding, but the roll paper 41 is bent by the decurling roller 17 to that extent. By doing so, the curl can be corrected uniformly. Therefore, it is possible to stabilize the state when the roll paper 41 is discharged. Note that the curl shape desired by the user can be corrected by setting.

  Thus, after the start of printing in step S9, the curl 41 whose curl has been corrected in step S10 and whose printing has been completed in step S11 is cut by the cutter 18 (see FIG. 4) in the next step S12 and discharged. Is done. Then, the discharged roll paper 41 has a quality because the curl is corrected and does not scatter around the discharge port 8 (see FIG. 1). Further, when the roll paper 41 is cut, the thermal printer 1 of the present embodiment is slightly in front and slightly behind the boundary between the printing end point of the roll paper 41 and the unexecuted portion of printing. The roll paper 41 is cut. Therefore, not only the curl attached to the roll paper 41 is corrected, but also the generated paper waste can be reduced to 2 to 3 mm.

  In the final step S13, the cam 22 is reversely rotated from the state shown in FIG. 7 to the state shown in FIG. 6, and the decurling roller 17 is lowered and moved to the retracted position so as not to hinder the new printing operation. Then, the printing operation ends. In the thermal printer 1 of the present embodiment, the paper waste is generated by 2 to 3 mm, but it is possible to prevent the paper waste from being generated at all.

  Therefore, according to the thermal printer 1 of the present embodiment, it is possible to achieve both reduction of paper waste and shortening of the printing time. That is, even if the conveying rollers (capstan roller 12 and pinch roller 13) are arranged upstream of the platen roller 11, the roll paper 41 is fed in the feed direction by causing the capstan roller 12 and the platen roller 11 to cooperate. Printing can be carried out while being conveyed. Therefore, it is possible to eliminate a margin generated by transporting the roll paper 41 by the transport roller disposed on the downstream side of the platen roller 11, and to adjust the vicinity of the boundary between the print end point and the unexecuted portion of the print. Paper waste can be reduced to only a small amount of paper waste. Further, compared with the case where printing is performed while the roll paper 41 is conveyed in the returning direction, the number of times the roll paper 41 is reciprocated between the start and end of the printing operation can be reduced by one reciprocation. Shortened.

  Furthermore, according to the thermal printer 1 of the present embodiment, the decurling roller 17 bends the roll paper 41 in the direction opposite to the curling direction of the roll paper 41 in a state where the residual heat during printing remains on the roll paper 41. Therefore, it is possible to correct the curl efficiently and adjust a wide range of correction amount, which is mechanically compact, without installing a heating means separately, and without burdening parts cost and manufacturing cost. Further, it is possible to obtain an excellent printing result in terms of quality such as durability while minimizing mechanical and thermal damage to the roll paper 41.

  (1) In this embodiment, the thermal printer 1 is used as an example of the image forming apparatus. However, the image forming apparatus is not limited to the thermal printer 1 and may be applied to various image forming apparatuses such as other types of printers and copiers. it can. In other words, the recording paper curl correcting mechanism of the present invention can be arranged downstream of the fixing device of the copying machine to correct the curl.

  (2) In the present embodiment, the roll paper 41 is used as the recording paper. However, the present invention is not limited to this, and cut paper can also be used. That is, even a cut sheet may be curled by heat from the thermal head 10 or the fixing device, and the curl can be corrected efficiently.

It is a perspective view which shows the thermal printer of this embodiment. FIG. 2 is a perspective view showing a state in which a door portion of the thermal printer of the present embodiment shown in FIG. 1 is opened, in which an ink cassette is taken out and illustrated. It is a top view which shows the ink ribbon used for the thermal printer of this embodiment shown in FIG. It is a side view which shows the outline of the internal structure of the thermal printer of this embodiment shown in FIG. 2 is a flowchart showing a printing operation by the thermal printer of the present embodiment shown in FIG. 1. FIG. 6 is a side view showing a peripheral portion of the thermal head shown in FIG. 4, and shows states of Step S <b> 3, Step S <b> 5, and Step S <b> 7 of the flowchart shown in FIG. 5. FIG. 6 is a side view showing a peripheral portion of the thermal head shown in FIG. 4 and shows a state of step S10 in the flowchart shown in FIG. It is a perspective view which shows the internal structure of the conventional thermal printer. It is a flowchart which shows the printing operation by the conventional thermal printer shown in FIG.

Explanation of symbols

1 Thermal printer (image forming device)
10 Thermal head 11 Platen roller (platen)
12 Capstan roller (conveyance roller)
13 Pinch roller (conveyance roller)
17 Decal roller 17 (curl correction means)
31 Ink ribbon 41 Roll paper (recording paper)

Claims (10)

This is a recording paper curl correction mechanism that is used in an image forming apparatus in which heat is transmitted from a heat source to the recording paper when printing is performed while the recording paper is conveyed, and for correcting curl attached to the recording paper. And
A curl correcting means capable of bending the recording paper in a direction opposite to the curling direction of the recording paper;
The curl correcting means is downstream of the heat source with respect to the feeding direction of the recording paper from the paper supply side to the paper discharge side, and residual heat at the time of printing by the heat source remains on the recording paper. A recording paper curl correction mechanism characterized by being arranged at a position. In the recording paper curl correction mechanism according to claim 1,
The recording paper curl correction mechanism, wherein the curl correction means is movable so as to contact or separate from the recording paper. In the recording paper curl correction mechanism according to claim 1,
The recording paper curl correction mechanism, wherein the curl correction means changes a degree of bending of the recording paper according to an environmental condition at the time of printing. In the recording paper curl correction mechanism according to claim 1,
The recording paper curl correction mechanism, wherein the curl correction means changes a degree of bending of the recording paper according to a material of the recording paper. In the recording paper curl correction mechanism according to claim 1,
The recording paper curl correction mechanism, wherein the curl correction means changes a degree of bending of the recording paper according to a conveyance speed of the recording paper. In the recording paper curl correction mechanism according to claim 1,
The curl correcting means changes the degree of bending of the recording paper according to the roll outer diameter of the roll paper when the recording paper is roll paper wound in a cylindrical shape. Paper curl correction mechanism. A transport roller for transporting recording paper;
A thermal head having a heating element;
A platen disposed opposite to the thermal head and sandwiching the recording paper with the thermal head when printing on the recording paper,
An image forming apparatus that performs printing by energizing and driving the heating element while transporting the recording paper sandwiched between the thermal head and the platen by rotation of the transport roller,
Comprising curl correction means capable of bending the recording paper in a direction opposite to the direction of curling applied to the recording paper;
The curl correcting means is a downstream side of the thermal head with respect to the feeding direction of the recording paper from the paper supply side to the paper discharge side, and residual heat at the time of printing by the thermal head remains on the recording paper. An image forming apparatus, wherein the image forming apparatus is disposed at a position. A recording paper curl correction method for correcting curl attached to the recording paper of the image forming apparatus in which heat is transferred from a heat source to the recording paper when performing printing while conveying the recording paper,
The recording paper in a state in which residual heat is left on the recording paper on the downstream side of the heat source with respect to the feeding direction of the recording paper from the paper supply side to the paper discharge side and at the time of printing by the heat source. A method of correcting the recording paper curl, characterized in that the recording paper is bent in a direction opposite to the curling direction. The recording paper curl correction method according to claim 8,
A method for correcting curling of recording paper, comprising: adjusting a curling correction amount attached to the recording paper by changing a degree of bending of the recording paper. A transport roller for transporting recording paper;
A thermal head that energizes and drives the heat generating element and sequentially transfers a plurality of inks on the ink ribbon to the recording paper;
A platen disposed opposite to the thermal head, and sandwiching the ink ribbon and the recording paper with the thermal head at the time of transferring each ink,
A recording paper curl correction method for an image forming apparatus that performs printing by sequentially transferring each ink while transporting the recording paper sandwiched between the thermal head and the platen by rotating the transport roller. ,
After the ink transferred last from the ink ribbon is transferred to the recording paper,
The recording paper in a state in which residual heat is left on the recording paper on the downstream side of the heat source with respect to the feeding direction of the recording paper from the paper supply side to the paper discharge side and at the time of printing by the heat source. A method of correcting the recording paper curl, characterized in that the recording paper is bent in a direction opposite to the curling direction.

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