JP2006043904A - Thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high print quality thermal printer in which poor printing, e.g. occurrence of white line, is prevented by feeding a recording sheet with no slack between a thermal head under head down state and a platen roller. <P>SOLUTION: A groove shallower than the thickness dimension of a recording sheet 1 and wider than the width dimension of the recording sheet 1 is formed in the outer circumferential surface of each platen roller 9-12 at such a part as each thermal head 5-8 comes into pressure contact with the recording sheet 1 so that each thermal head 5-8 under head down state can bring the recording sheet 1 into pressure contact with the groove of each platen roller 9-12. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermal printer, and more particularly to a thermal printer capable of conveying a recording sheet with high accuracy during printing and printing a high-quality image without image distortion.

A conventional thermal printer will be described based on Patent Document 1. As shown in FIG. 9, the thermal printer is provided with a plurality of ink ribbons 31 to which inks of different colors are applied.
The ink ribbon 31 includes an ink ribbon 31y applied with yellow (Y) color ink, an ink ribbon 31m applied with magenta (M) color, an ink ribbon 31c applied with cyan (C) ink, An ink ribbon 31b coated with black (B) ink is disposed in order from the right side in the figure.

The respective ink ribbons 31y, 31m, 31c and 31b are wound around supply reels 32y, 32m, 32c and 32b in a roll shape, guided by guide rollers 33 and 34, and take-up reels 35y, 35m, 35c and 35b. It is possible to wind up.
Further, the thermal heads 36y, 36m, 36c, 36b corresponding to the ink ribbons 31y, 31m, 31c, 31b of the respective colors and the thermal heads 36y, 36m, 36c, 36b are connected to the ink ribbons 31y, 31m, 31c, 31b. In addition, platen rollers 38y, 38m, 38c, and 38b that are press-contactable via a recording paper 37 made of roll paper are arranged adjacent to each other with a predetermined interval.

Further, the recording paper 37 is conveyed in the direction of arrow A by the first paper feed roller 39, and the leading end pushes up the thermal heads 36y, 36m, 36c, 36b with the heads down, and the platen rollers 38y, 38m, 38c, 38b. It is designed to be pressed between the two.
Further, intermediate rollers 41, 42, and 43 capable of conveying the recording paper 37 being printed to the downstream side in the direction of arrow A are disposed between the platen rollers 38y, 38m, 38c, and 38b.
In addition, a second paper feed roller 40 is disposed on the left side, which is the downstream side of the platen roller 38b on the left side of the figure, and a cutter 44 is disposed on the downstream side of the second paper feed roller 40. The recording sheet 37 after printing can be cut for each image.

The printing operation of such a conventional thermal printer will be described. First, the recording sheet 37 transported to the downstream side in the direction of arrow A by the pair of first paper feed rollers 39 is the first platen on the right side in the drawing. As shown in FIG. 10, it is guided by the roller 38y and hits the thermal head 36y in the head down state via the ink ribbon 31y. As a result, a large transport load is generated on the recording paper 37 being transported.
When the recording paper 37 is further conveyed downstream in the direction of the arrow A by the first paper feed roller 39 in a state where a large conveyance load is generated on the recording paper 37, the thermal head 36y is moved upward by the leading end of the recording paper 37. When pushed up, the leading end of the recording paper 37 is pressed between the thermal head 36y and the platen roller 38y. As a result, the Y color ink of the ink ribbon 31 y is transferred from the leading end of the recording paper 37, and the Y color image is printed on the recording paper 37.

Next, the recording paper 37 on which an image of Y color is printed is conveyed to the downstream side by a pair of intermediate rollers 41, and the leading end pushes up the thermal head 36m in the head down state and is pressed and clamped by the platen roller 38m. The
At the same time, the M color ink on the ink ribbon 31m is transferred onto the Y color image, and the M color image is overprinted.
Thereafter, in the same manner, an image of C color is overprinted on the image of M color, and an image of B color is overprinted on the image of C color, so that one image worth is recorded on the recording paper 37. A color image is printed.

Then, the printed recording paper 37 sandwiched between the second paper feed rollers 40 is cut out by the cutter 44 and the color image for one image is cut out and discharged to the outside of the printer.
Thereafter, when printing the same image continuously, the recording head 37 is transported downstream in the direction of arrow A while keeping the thermal heads 36y, 36m, 36c, and 36b down, so that the same image is continuously printed. Can be printed.
After the printing is finished, the thermal heads 36y, 36m, 36c, and 36b are raised, the first paper feed roller 39 is reversed, and the recording paper 37 is placed upstream of the first thermal head 36y and the platen roller 38y. Rewind to the side.
As a result, the thermal printer enters a standby state before starting printing.
JP-A-08-281985 JP 07-214843 A Japanese Patent Laid-Open No. 05-177853

  However, in the conventional thermal printer, when the recording paper 37 conveyed in the direction of arrow A before the start of printing pushes up the thermal head 36y in the head down state, a large conveyance load is generated on the recording paper 37. At this time, the recording paper 37 is partially bent due to a large conveyance load, and the printed image may be partially disturbed to cause a printing defect such as a white line in the printed image. .

Such a printing defect such as a white line may occur not only in the first thermal head 36y but also in the subsequent thermal heads 36m, 36c, and 36b.
The present invention solves the above-described problems, and transports recording paper between a thermal head in a head-down state and a platen roller without bending, so that high printing quality that does not cause printing defects such as white lines. It is an object of the present invention to provide a summary printer.

  As a first means for solving the above problems, a printer according to the present invention includes a thermal head composed of a long line head, a cylindrical platen roller to which the thermal head can be pressed, the platen roller, and the thermal head. A recording sheet that is held in pressure contact with the head and can be conveyed by rotation of the platen roller, and the outer peripheral surface of the platen roller at the portion where the recording sheet is pressed against is deeper than the thickness of the recording sheet The thermal head that is shallow and has a width that is wider than the width of the recording paper is formed so that the thermal head can be pressed against the groove of the platen roller. To do.

  Further, as a second means for solving the above-mentioned problem, the thermal head is characterized in that the longitudinal dimension is formed wider than the width dimension of the groove.

  As a third means for solving the above-mentioned problem, a plurality of the thermal heads are arranged adjacent to each other at a predetermined interval, and the platen roller is disposed on the side where the plurality of thermal heads face each other. Each is arranged.

  In addition, as a fourth means for solving the above-described problem, an ink ribbon to which ink of different colors is applied is drawn around the plurality of thermal heads.

In the printer according to the present invention, a groove portion having a depth smaller than the thickness of the recording paper and a width wider than the width of the recording paper is formed on the outer peripheral surface of the platen roller at the portion where the recording paper is pressed. The down thermal head can press the recording paper against the groove of the platen roller. Quality image printing can be performed.
In addition, the conveyance load generated on the recording sheet being conveyed can be reduced, the recording sheet is not bent, and printing defects such as a white lie can be eliminated.

  Also, since the thermal head has a longitudinal dimension wider than the width of the groove, a gap is formed between the thermal head and the thermal head that heads down before printing due to the groove, and the gap is located in the groove. Therefore, the thermal head with the recording sheet conveyed down can be pushed up without difficulty.

  In addition, a plurality of thermal heads are disposed adjacent to each other with a predetermined interval, and the platen roller is disposed on the side where the plurality of thermal heads face each other, so that the diameter dimension of the platen roller can be reduced, A small thermal printer can be provided.

  In addition, since the ink ribbons to which different colors of ink are applied are drawn around the thermal heads, the running cost of the ink ribbons can be improved.

  The thermal printer of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram for explaining a thermal printer according to a first embodiment of the present invention. FIGS. 2 to 4 are diagrams for explaining a printing operation of the thermal printer shown in FIG. FIG. 8 is a diagram for explaining a platen roller shown in FIG. 1, and FIG. 8 is a diagram for explaining a thermal printer according to a second embodiment of the present invention.

First, the thermal printer according to the first embodiment of the present invention will be described as a tandem printer in which a plurality of thermal heads are provided for each color of ink to be printed, for example.
In such a thermal printer, as shown in FIG. 1, a recording paper 1 made of thick paper such as photographic paper with a predetermined width is made of roll paper and wound around a paper take-up roller 2 in a roll shape.
The recording paper 1 is held in pressure contact with the paper feed roller 3 and the pressure contact roller 3a, and can be conveyed downstream in the direction of arrow B by the rotation of the paper feed roller 3.
The recording paper 1 conveyed in the direction of arrow B by the paper feed roller 3 and the pressure roller 3a is conveyed upward in the figure by a first paper guide 4 curved in an arc shape.

Also, the first to fourth thermal heads 4 to 8 are disposed at a predetermined interval on the downstream side (upper side in the drawing) from the first paper guide 4 in the conveyance direction indicated by the arrow B. First to fourth platen rollers 9 to 12 are disposed on the side facing the fourth thermal heads 4 to 8 with a gap of a predetermined size. The first to fourth platen rollers 9 to 12 can be driven to rotate. The first to fourth thermal heads 5 to 8 can be head-down. The four platen rollers 9 to 12 can be pressed against each other.

  Further, a first ink ribbon 13 coated with, for example, yellow (Y) color ink is drawn between the first thermal head 5 and the first platen roller 9, and the first ink ribbon 13 is taken up by a take-up reel. 13a and a supply reel 13b. Further, between the second thermal head 6 and the second platen roller 10, for example, a second ink ribbon 14 coated with magenta (M) color ink is wound around the take-up reel 14a and the supply reel 14b. Has been routed.

Further, between the third thermal head 7 and the third platen roller 11, for example, a third ink ribbon 15 coated with cyan (C) color ink is wound around the take-up reel 15a and the supply reel 15b. Has been routed.
Further, between the fourth thermal head 8 and the fourth platen roller 12, for example, a fourth ink ribbon 16 coated with a transparent overcoat layer (OV layer) is wound around the take-up reel 16a and the supply reel 16b. It has been turned around.

Further, an intermediate roller 17 and a pressure roller 17a that is in pressure contact with the intermediate roller 17 are disposed on the downstream side of each of the first to fourth platen rollers 9 to 12 in the conveyance direction of the recording paper 1 indicated by the arrow B. The recording paper 1 can be guided and conveyed downstream.
A second paper feed roller 18 is disposed on the downstream side of the fourth platen roller 12 via an intermediate roller 17 located on the most downstream side in the uppermost part of the figure, and the second paper feed roller 18 is in contact with the pressure roller. 18a is in pressure contact.
The second paper feed roller 18 is a second paper that can guide the printed recording paper 1 conveyed from the most downstream intermediate roller 17 between the second paper feed roller 18 and the pressure roller 18a. A guide 19 is provided.

A cutting device 20 having a cutter 20a for cutting the recording paper 1 made of printed roll paper is disposed on the left side of the drawing, which is the downstream side of the second paper feed roller 18, and the cutting device 20 includes: A paper tray 21 that can store the color image paper 1A after printing cut by the cutter 20a of the cutting device 20 is disposed on the left side in the drawing, which is the downstream side.
The first to fourth platen rollers 9 to 12 according to the present invention will be described with reference to the first platen roller 9 shown in FIGS. 5 to 7. The first platen roller 9 has a recording sheet 1 on the outer peripheral surface 9a. A groove 9b having a width dimension E that is wider than the width dimension D of the recording paper 1 is formed.

Further, the first thermal head 5 is formed such that the longitudinal dimension, which is the left-right direction shown in FIG. 7, is wider than the width dimension E of the groove 9b.
Therefore, a dimension corresponding to the depth dimension C of the groove portion 9b is provided between the first thermal head 5 which is lowered by an urging force of an elastic member or the like and the first platen roller 9 in the portion where the groove portion 9b is formed. A gap is formed.
Therefore, even if the recording paper 1 is transported with a small transport force, the head-down first thermal head 5 can be pushed up smoothly and smoothly against the urging force, and bends to the recording paper 1 being transported. Etc. are not generated.
Also, the second to fourth platen rollers 10 to 12 are formed with grooves (not shown) similar to the first platen roller 9.

The printing operation of the thermal printer according to the first embodiment of the present invention having such a configuration will be described with reference to FIGS. 2 to 4. First, as shown in FIG. 2, first to fourth thermal heads 5. -8 are headed down and pressed against the first to fourth platen rollers 9-12.
Thereafter, when the first paper feed roller 3 is driven to rotate, the leading edge of the recording paper 1 is conveyed to the first thermal head 5 and the first platen roller 9.

Then, the leading end portion of the recording paper 1 is positioned in the groove portion 9b having the depth dimension C of the first platen roller 9, and the first thermal head 5 is smoothly pushed up against the urging force and pressed against the first thermal head 5. At the same time, the recording paper 1 is cued with respect to the first thermal head 5.
Therefore, the recording paper 1 being conveyed in the direction of the arrow B is not bent, and it is possible to prevent a printing defect such as a white line from occurring in the Y color image.

Simultaneously with the cueing of the recording paper 1, the plurality of heating elements of the first thermal head 5 selectively generate heat based on the print information of the Y color image, and the Y color of the first ink ribbon 13 is changed. Ink is conveyed in the direction of arrow B while being transferred from the leading edge of the recording paper 1. As a result, a Y color image is printed on the recording paper 1.
Further, the recording paper 1 on which an image of Y color is being printed is conveyed to the second platen roller 10 on the downstream side, and is pressed and clamped by the second thermal head 6, and the recording paper 1 on the second thermal head 6 is pressed. Cueing is performed, and an image of M color is overprinted on an image of Y color.
Next, in a similar printing operation, the third thermal head 7 prints a desired color image on the recording paper 1 by overprinting the C color image on the M color image.

Thereafter, the leading end portion of the recording paper 1 on which a desired color image is printed is conveyed to the fourth thermal head 8 and the head of the fourth thermal head 8 is positioned, and the OV layer is overprinted on the color image. The upper surface of the color image is coated.
The recording paper 1 coated with a color image with such an OV layer is conveyed downstream, and is fed by the second paper guide 19 through the second paper guide 19 by the intermediate roller 17 and the pressure roller 17a on the most downstream side. The roller 18 and the pressure roller 18a are pressed and sandwiched.
Then, the recording sheet 1 on which the color image is printed is conveyed to the cutting device 20, and the color image sheet 1 </ b> A separated from the recording sheet 1 by cutting one image is dropped and stored in the sheet tray 21. .

When the same image is continuously printed on the recording paper 1, the recording paper 1 is cued with respect to the thermal heads 5 to 8 by controlling the rotational speed of the platen rollers 9 to 11. The same image can be printed continuously.
If the image to be printed is different, the thermal heads 5 to 8 are headed up, and the first and second paper feed rollers 3 and 18 and the paper take-up roller 2 around which the recording paper 1 is wound are reversed. Thus, by rewinding the recording paper 1, another color image can be printed on the recording paper 1 again.

  The thermal printer according to the first embodiment of the present invention has the same groove portion as the groove portion 9b formed in the first platen roller 9 as shown in FIG. 7 in each of the first to fourth platen rollers 10-12. Therefore, when the recording paper 1 corresponding to each of the thermal heads 5 to 8 is cued, the thermal heads 6 to 8 are smoothly pushed up, and the recording paper 1 is bent as in the conventional example. Therefore, it is possible to prevent printing defects such as white lines from occurring in each color image.

Further, in the thermal printer according to the second embodiment of the present invention, as shown in FIG. 4, the recording paper 1 made of the same roll paper as that of the first embodiment is wound around the paper take-up roller 2. . Then, the recording paper 1 is conveyed by the guide roller 51 and drawn around the outer peripheral surface 52a of one cylindrical platen roller 52 having a large outer diameter.
The platen roller 52 can be driven to rotate in the clockwise direction and the counterclockwise direction. The outer peripheral surface 52 a has a depth smaller than the thickness dimension of the recording sheet 1 and is smaller than the width dimension of the recording sheet 1. A wide groove (not shown) is formed, and the recording paper 1 is routed and positioned in this groove.
Then, the recording paper 1 positioned so as to be drawn around the groove part slightly protrudes from the groove part and can be conveyed in the arrow G direction by the rotation of the platen roller 52 in the arrow F direction.

Further, first to fourth thermal heads 53 to 56 are disposed at substantially equal intervals on the outer peripheral surface 52 a side of the platen roller 52, and yellow (Y) is provided between the platen roller 52 and the first thermal head 53. The first ink ribbon 57 coated with the color ink) is wound around the take-up reel 57a and the supply reel 57b.
A second ink ribbon 58 coated with magenta (M) color ink is wound around the take-up reel 58a and the supply reel 58b between the platen roller 52 and the second thermal head 54. Has been.

A third ink ribbon 59 coated with cyan (C) color ink is wound around the take-up reel 59a and the supply reel 59b between the platen roller 52 and the third thermal head 55. Has been.
A fourth ink ribbon 60 coated with a transparent overcoat layer (OV layer) is wound around the take-up reel 60a and the supply reel 60b between the platen roller 52 and the fourth thermal head 56. Has been routed.

Further, on the downstream side of the fourth thermal head 56 in the conveying direction of the arrow G of the recording paper 1, the same cutting device 20 and paper tray 21 as those in the first embodiment are disposed and cut by the cutting device 20. The color image paper 1A can be stored.
Each of the thermal heads 53 to 56 in the second embodiment is formed so that the dimension in the longitudinal direction (perpendicular to the paper surface) is wider than the width dimension of the groove portion of the platen roller 52.
For this reason, a gap having a dimension corresponding to the depth of the groove is formed between each of the thermal heads 53 to 56 whose head is down and the platen roller 52 in the portion where the groove is formed.

In the printing operation of the thermal printer according to the second embodiment of the present invention having such a configuration, first, the thermal heads 53 to 56 are brought down and brought into pressure contact with the platen roller 52. Thereafter, the recording paper 1 wound around the paper take-up roller 2 is conveyed to the groove portion of the platen roller 52 by the rotation of the guide roller 51.
When the platen roller 52 is rotationally driven in the direction of arrow F, the leading edge of the recording paper 1 is sandwiched between the first thermal heads 53 headed down, and the recording paper 1 is cued with respect to the first thermal head 53. Is called.

Simultaneously with the cueing of the recording paper 1 with respect to the first thermal head 53, the plurality of heating elements of the first thermal head 53 selectively generate heat based on the printing information of the Y color image, and the first ink ribbon. 57 Y-color ink is transferred from the leading end of the recording paper 1, and a Y-color image is printed on the recording paper 1 conveyed in the direction of arrow G.
Then, the leading end portion of the recording paper 1 on which the Y color image is printed is conveyed to the second thermal head 54 and is pressed and clamped, and the recording paper 1 is cued with respect to the second thermal head 54, so that the Y color is obtained. An image of M color is overprinted on the image of.
Thereafter, in the same printing operation, the third thermal head 55 prints a desired color image on the recording paper 1 by overprinting the C color image on the M color image.

Thereafter, the leading end portion of the recording paper 1 on which a desired color image is printed is conveyed to the fourth thermal head 56, the head is positioned with respect to the fourth thermal head 56, and the OV layer is overprinted on the color image. The
The recording paper 1 on which such an OV layer is formed is conveyed downstream, and the recording paper 1 on which one image has been printed by the cutting device 20 is cut, and the color image paper 1A falls onto the paper tray 21. And stored.

In such a thermal printer according to the second embodiment of the present invention, the platen roller 52 is provided with a groove portion having a depth smaller than the thickness dimension of the recording paper 1 and a width dimension wider than the width dimension of the recording paper 1 ( (Not shown), a large transport load is not applied to the recording paper 1 when cueing the recording paper 1 with respect to each of the thermal heads 53 to 56. For this reason, the recording paper 1 does not bend, and printing defects such as white lines can be prevented from occurring in each color image.
Further, since the thermal printer of the second embodiment has one platen roller, the number of parts is reduced and the assemblability is good.

In the first and second embodiments of the present invention, the tandem thermal printer in which a plurality of thermal heads are arranged has been described. However, each of the platen roller and the thermal head has one thermal printer (see FIG. (Not shown).
Ink ribbons that are used in a thermal printer each of which includes a platen roller and a thermal head are formed by repeatedly applying inks of different colors Y, M, and C and an OV layer in order to one ink ribbon. Yes.
Then, the recording paper on which the Y color ink is printed is back-fed back, the M color image is overprinted on the Y color image, and then the same operation is performed, and then the C color is printed on the M color image. The color images are overprinted to form a color image, and an OV layer is printed on the color image.

It is the schematic explaining the thermal printer of the 1st Embodiment of this invention. It is a figure explaining the printing operation of the thermal printer shown in FIG. It is a figure explaining the printing operation of the thermal printer shown in FIG. It is a figure explaining the printing operation of the thermal printer shown in FIG. It is a figure explaining the platen roller shown in FIG. It is a figure explaining the platen roller shown in FIG. It is a figure explaining the platen roller shown in FIG. It is the schematic explaining the thermal printer of the 2nd Embodiment of this invention. It is the schematic explaining the conventional thermal printer. It is a principal part enlarged view explaining the printing operation of the conventional thermal printer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Recording paper 2 Paper winding roller 3 1st paper feed roller 3a Pressure roller 4 1st paper guide 5 1st thermal head 6 2nd thermal head 7 3rd thermal head 8 4th thermal head 9 1st platen roller 10 2nd Platen roller 11 Third platen roller 12 Fourth platen roller 13 First ink ribbon 18 Second paper feed roller 20 Cutting device 21 Paper tray

Claims (4)

  A thermal head composed of a long line head, a cylindrical platen roller to which the thermal head can be pressure-contacted, and press-clamped between the platen roller and the thermal head, and can be conveyed by the rotation of the platen roller. A groove portion having a depth smaller than a thickness dimension of the recording paper and a width dimension wider than the width dimension of the recording paper on an outer peripheral surface of the platen roller at a portion that presses the recording paper. The thermal printer formed and head-down is capable of pressing the recording paper against the groove of the platen roller.   The thermal printer according to claim 1, wherein the thermal head has a longitudinal dimension wider than a width dimension of the groove.   The thermal head is provided in a plurality adjacent to each other with a predetermined interval, and the platen roller is provided on a side where the plurality of thermal heads are opposed to each other. 2. The thermal printer according to 2. 4. The thermal printer according to claim 3, wherein an ink ribbon to which inks of different colors are applied is drawn around the plurality of thermal heads.

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