JP3993053B2 - Thermal transfer printer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thermal transfer printer, and more particularly to a thermal transfer printer capable of eliminating a recording medium conveyance shift when a thick recording medium such as photographic paper capable of color printing is reciprocally conveyed.
[0002]
[Prior art]
Although not shown in the figure, a conventional thermal transfer printer rotationally drives a paper feed roller in a state where a recording medium made of thick photographic paper capable of color printing is pressed between the paper feed roller and a driven roller. As a result, the recording medium can be reciprocated between the platen roller and the thermal head.
The platen roller is rotatable with low torque, and the thermal head is a long line head, and the thermal head can be brought into contact with and separated from the platen roller, that is, the head can be raised / lowered. It has become.
[0003]
Further, an ink ribbon having a width dimension substantially equal to the width dimension of the recording medium is routed between the platen roller in the head-up state and the thermal head. The ink ribbon is repeatedly applied with a plurality of different colors of ink in order in the drawing direction.
[0004]
In order to print a desired color image on a recording medium using such a conventional thermal transfer printer, the thermal head is moved down with the recording medium pressed between the paper feed roller and the driven roller, and the ink ribbon and The recording medium is pressed against the platen roller.
Then, the recording medium is pressed by the thermal head and the platen roller while the paper feed roller is driven to rotate, and the plurality of heating elements of the thermal head are selectively heated based on the printing information, thereby recording the recording medium. The first color image can be printed.
[0005]
When the image printing of the first color is finished, the thermal head is headed up for non-printing, and the paper feed roller is reversed to back feed the recording medium in the direction of the platen roller.
Then, the same operation as when printing the first color image is repeated, and a plurality of different color images are overprinted on the first color image so that the color image of the desired color is printed on the recording medium. Can be printed.
[0006]
When not printing, the recording medium is back-fed in a state of being in contact with a platen roller that is rotatable with low torque.
Therefore, the recording medium that is back-fed at the time of non-printing can be transported with a very small transport load of 50 to 100 gf.
[0007]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-19208 [Patent Document 2]
Japanese Patent Laid-Open No. 2001-38931
[Problems to be solved by the invention]
However, since the conventional thermal transfer printer as described above presses the recording medium against the platen roller with a thermal head during printing, a large transport load of about 1 Kgf is applied to the recording medium.
Therefore, in the conventional thermal transfer printer, the transport load applied to the recording medium during printing is 10 times or more than the transport load applied to the recording medium during non-printing , and the transport accuracy when reciprocating the recording medium during color printing is achieved. Could get worse.
When the conveyance accuracy of such a recording medium is deteriorated, the position of the ink to be overprinted during color printing is shifted, and the print quality of the color image may be deteriorated.
[0009]
The present invention has been made in view of the above-described points. When a recording medium is back-fed at the time of non-printing, a predetermined rotational load is applied to the platen roller so that a predetermined amount is applied to the recording medium being back-fed. Provided is a thermal transfer printer capable of improving the conveyance accuracy of a recording medium by applying a conveyance load and reducing the magnification of the conveyance load applied to the recording medium during printing with respect to the conveyance load applied to the recording medium during non-printing. For the purpose.
[0010]
[Means for Solving the Problems]
As a first means for solving the above problems, a thermal transfer printer according to the present invention includes a paper feed roller capable of reciprocating a recording medium, a thermal head capable of printing a desired image on the recording medium, and this thermal head. A platen roller that can be pressure-contacted via the recording medium, a torque urging member that can urge a predetermined rotational load is disposed on the platen roller, and during printing of the image on the recording medium, The recording medium press-contacted between the thermal head and the platen roller is pulled by the paper feed roller, and after printing, the press-contact is released and the recording medium is back-fed in the direction opposite to the pulling direction. doing, this said platen roller is rotated against the predetermined rotational load by the torque biasing member, before type recording medium a predetermined conveying load is to be applied The features.
[0011]
The torque urging member may be a friction member capable of urging the platen roller.
[0012]
Further, the torque urging member comprises a coil spring inserted and supported by the rotation shaft of the platen roller, and this coil spring elastically urges the side surface of the platen roller.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a thermal transfer printer according to the present invention will be described with reference to FIGS. 1 and 2 are schematic diagrams for explaining the printing operation of the thermal transfer printer of the present invention, FIG. 3 is a schematic diagram when the recording medium is back-fed in the thermal transfer printer of the present invention, and FIG. 4 relates to the present invention. It is the schematic explaining the torque biasing member of a platen roller.
[0014]
First, as shown in FIG. 1, the thermal transfer printer of the present invention can use a recording medium 1 made of thick photographic paper or the like capable of printing a color image or the like. 2 and the driven roller 3 can be pressed against each other. The recording medium 1 held in pressure contact between the paper feed roller 2 and the driven roller 3 is rotated in the clockwise direction or the counterclockwise direction by driving the paper feed roller 2 clockwise or counterclockwise. Can be reciprocated.
Further, on the upstream side (the right side in the figure) of the paper feed roller 2 in the conveyance direction indicated by the arrow A, a rotatable platen roller 4 and a thermal head 5 that can come into contact with and separate from the platen roller 4, that is, a head up / down. Is arranged.
[0015]
The platen roller 4 has a cylindrical shape and is formed in a long shape in a direction perpendicular to the paper surface. In order to increase the frictional resistance with the recording medium 1, a friction member (not shown) is formed on the outer peripheral surface from rubber or the like. ) Is covered. Further, the thermal head 5 is formed in a long shape parallel to the longitudinal direction of the platen roller 4, and a plurality of heating elements (not shown) are aligned and formed in a portion facing the platen roller 4.
Then, the recording medium 1 in a state of being pressed and sandwiched between the paper feed roller 2 and the driven roller 3 is transported between the head-up platen roller 4 and the thermal head 5 in the conveying direction indicated by the arrow A, or back fed as indicated by the arrow B. It can be transported in the direction.
[0016]
An ink ribbon (not shown) formed to have a width dimension substantially equal to the width dimension of the recording medium 1 is drawn between the platen roller 4 and the thermal head 5 in the head-up state.
In this ink ribbon, for example, inks of a plurality of colors such as yellow (Y), magenta (M), cyan (C), and black (K) are sequentially arranged in an area approximately the same as the area of one sheet of the recording medium 1. Has been applied repeatedly.
Further, a torque urging member 6 capable of urging a predetermined rotational load is disposed on the platen roller 4, and this torque urging member 6 is a coil spring having a predetermined line shape and the number of turns as shown in FIG. 4. The coil spring is inserted into and supported by the rotation shaft 4 a of the platen roller 4 and is compressed between the side wall 7 of the main body case (not shown) and the side surface 4 b of the platen roller 4.
Therefore, the platen roller 4 is elastically urged by a coil spring whose side surface 4b is a torque urging member 6 to urge a predetermined rotational load.
[0017]
In order to print a desired color image on the recording medium 1 by the thermal transfer printer of the present invention having such a configuration, first, as shown in FIG. 1, the recording medium 1 is interposed between the paper feed roller 2 and the driven roller 3. Feed the paper and clamp it.
The recording medium 1 can be fed to the paper feed roller 2 in the direction of arrow A from the right side of the paper feed roller 2 or in the direction of arrow B from the left side of the drawing.
Then, the recording medium 1 fed between the paper feed roller 2 and the driven roller 3 is cued when a paper detection sensor (not shown) detects the front end 1a, and the paper feed roller The rotation of 2 stops temporarily.
Thereafter, as shown in FIG. 2, the thermal head 5 is lowered to press the recording medium 1 and the ink ribbon against the platen roller 4.
[0018]
Next, the paper feed roller 2 is rotated counterclockwise to pull the recording medium 1 in the direction of arrow A, and the plurality of heating elements of the thermal head 5 are selectively heated based on the print information. A first color ink, for example, a Y color ink, is thermally transferred to the printing surface 1b of the recording medium 1 to print a Y color image.
At the time of printing, the pressure contact pressure of the thermal head 5 is set so that the conveyance load of the recording medium 1 pulled in the direction of arrow A by the paper feed roller 2 and the driven roller 3 is approximately 1 Kgf equivalent to the conventional one. ing.
[0019]
Next, when the printing of the Y color image is completed, as shown in FIG. 3, the thermal head 5 is raised, the pressure contact between the thermal head 5 and the platen roller 4 is released (head-up), and the paper feed roller 2 is reversed in the clockwise direction, and the recording medium 1 during non-printing is back-fed in the direction of arrow B.
When the recording medium 1 is back-fed to the cueing position, the cueing is performed again, and then the M color ink is overprinted on the first Y color image.
Thereafter, the same printing operation is repeated, and a color image of a desired color is printed on the recording medium 1 by overprinting the inks of C color and K color.
[0020]
During the printing operation as described above, the recording medium 1 that is back-fed in the direction of arrow B is back-fed while being in contact with the outer peripheral surface of the platen roller 4 having a large frictional resistance. Therefore, the platen roller 4 rotates against a predetermined rotational load by the torque urging member 6 so that the recording medium 1 is back-fed.
The recording medium 1 that is back-fed in the direction of arrow B is given a transport load of about 200 gf, which is at least twice as large as before.
[0021]
In this way, by providing the torque urging member 6, the same transport load is applied to the recording medium 1 regardless of the transport direction, so that the thermal head 5 is lifted up during non-printing. The magnification of the conveyance load applied to the recording medium 1 at the time of printing with the thermal head 5 down can be reduced with respect to the conveyance load at the time of back feed.
Therefore, the conveyance accuracy of the recording medium 1 during the printing operation can be improved.
[0022]
As another method for increasing the conveyance load of the recording medium 1 during back feed, the recording medium 1 is placed on the outer peripheral surface of the platen roller 4 while the rotation of the platen roller 4 is stopped while the recording medium 1 is back fed. A method of sliding the 1 is also conceivable. However, in this method, since the outer peripheral surface of the platen roller 4 is covered with rubber or the like having a large frictional resistance, the recording medium 1 cannot be smoothly slid, and the recording medium 1 becomes intermittently fed. There is a possibility that the conveyance accuracy may be lowered.
[0023]
In the embodiment of the present invention, the head down operation has been described by moving the thermal head 5 to the platen roller 4 side. However, the thermal head 5 is fixed and the platen roller 5 is moved to the thermal head 5 side. It may be something like this. In the embodiment of the present invention, the torque urging member 6 is described as a coil spring. However, the torque urging member 6 is provided with a friction clutch (not shown) disposed on the rotating shaft 4 a of the platen roller 4. It is also possible to provide a platen roller 4 with a predetermined rotational load.
That is, the torque urging member 6 may be any member that can urge the platen roller 4 with a predetermined rotational load.
[0024]
【The invention's effect】
As described above, the thermal transfer printer according to the present invention allows the platen roller to rotate against a predetermined rotational load by the torque urging member, so that recording is performed during printing with respect to the transport load applied to the recording medium during non-printing. The magnification of the conveyance load applied to the medium can be reduced, and the conveyance accuracy of the recording medium during the printing operation can be improved.
Therefore, when printing a color image, it is possible to eliminate printing misalignment when the ink of the ink ribbon is overprinted, and it is possible to print a high-quality color image.
[0025]
Further, since the torque urging member is made of a friction member capable of urging the platen roller, an appropriate friction member can be properly used corresponding to the friction urging force, and the degree of freedom in design can be improved.
[0026]
The torque biasing member is a coil spring that is inserted into and supported by the rotation shaft of the platen roller, and the coil spring elastically biases the side surface of the platen roller. it can.
[Brief description of the drawings]
FIG. 1 is a schematic diagram illustrating a printing operation of a thermal transfer printer of the present invention.
FIG. 2 is a schematic diagram illustrating a printing operation of the thermal transfer printer of the present invention.
FIG. 3 is a schematic view when the recording medium is back-fed in the thermal transfer printer of the present invention.
FIG. 4 is a schematic view for explaining a torque urging member of a platen roller according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Recording medium 2 Paper feed roller 3 Driven roller 4 Platen roller 5 Thermal head 6 Torque biasing member

Claims (3)

A paper feed roller capable of reciprocating the recording medium, a thermal head capable of printing a desired image on the recording medium, and a platen roller capable of being pressed against the recording medium via the recording medium. Is provided with a torque urging member capable of urging a predetermined rotational load, and during printing of the image on the recording medium, the recording medium press-contacted between the thermal head and the platen roller is Pulled by the paper feed roller, and after the printing is finished, the pressure contact is released and the recording medium is back-fed in the direction opposite to the pulling direction to resist the predetermined rotational load by the torque biasing member. thermal transfer printer, wherein the platen roller is rotated, a predetermined transport load before type recording medium is to be applied. 2. The thermal transfer printer according to claim 1, wherein the torque biasing member is a friction member capable of frictionally biasing the platen roller. 3. The thermal transfer according to claim 1, wherein the torque urging member comprises a coil spring inserted and supported by a rotation shaft of the platen roller, and the coil spring elastically urges a side surface of the platen roller. Printer.

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