JP2004106219A - Thermal transfer printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer printer in which carrying accuracy of a recording medium can be enhanced by applying a specified rotational load to a platen roller when the recording medium is back fed during nonprint operation and imparting a specified carrying load to the recording medium under back feed thereby reducing the difference of carrying load being applied to the recording medium between print operation and nonprint operation. <P>SOLUTION: The thermal transfer printer can reduce the difference of carrying load being applied to the recording medium between print operation and nonprint operation because the recording medium 1 is back fed in the direction of arrow B while touching the outer circumferential surface of a platen roller 4, and the platen roller 4 rotates while resisting against a specified rotational load being applied from a torque applying means 6 to impart a specified carrying load to the recording medium 1 during back feed in the direction of arrow B. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD 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 deviation when reciprocating a thick recording medium such as photographic paper capable of color printing.
[0002]
[Prior art]
Although not shown, a conventional thermal transfer printer rotates a paper feed roller in a state in which a recording medium made of thick photographic paper capable of performing color printing is pressed against a paper feed roller and a driven roller. Thus, 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. The thermal head can be moved toward and away from the platen roller. Has become.
[0003]
Further, an ink ribbon having a width substantially equal to the width of the recording medium is routed between the platen roller in the head-up state and the thermal head. The ink ribbon is repeatedly coated with a plurality of inks of different colors sequentially in the drawing direction.
[0004]
In order to print a desired color image on a recording medium by such a conventional thermal transfer printer, the thermal head is moved down while the recording medium is pressed between the paper feed roller and the driven roller, and the ink ribbon is formed. The recording medium is pressed against the platen roller.
The recording medium is pressed by the thermal head and the platen roller to pull the recording medium in rotation by rotating the paper feed roller, and selectively heats a plurality of heating elements of the thermal head based on the printing information. The first color image can be printed.
[0005]
When the printing of the image of the first color is completed, the thermal head is raised to make no printing, and the paper feed roller is reversed to feed the recording medium back toward the platen roller.
Then, by repeating the same operation as when printing the image of the first color, a plurality of images of different colors are overprinted on the image of the first color, so that the color image of the desired color is printed on the recording medium. Can be printed.
[0006]
At the time of non-printing, the recording medium is back-fed while being in contact with a low-torque rotatable platen roller.
Therefore, a recording medium that is back-fed during non-printing can be transported with a very small transport load of 50 to 100 gf.
[0007]
[Patent Document 1]
JP-A-2001-19298 JP-A-2001-38931
[Problems to be solved by the invention]
However, in the above-described conventional thermal transfer printer, the recording medium is pressed against the platen roller by the thermal head during printing, so that a large transport load of approximately 1 kgf is applied to the recording medium.
For this reason, in the conventional thermal transfer printer, the difference in the transport load applied to the recording medium between printing and non-printing is as large as 10 times or more, and the transport accuracy when reciprocating the recording medium during color printing may be deteriorated. was there.
If the conveyance accuracy of such a recording medium deteriorates, the position of the ink to be overprinted during color printing may be shifted, and the print quality of a color image may be degraded.
[0009]
The present invention has been made in view of the above-described point, and when a recording medium is back-fed during non-printing, a predetermined rotation load is applied to a platen roller to apply a predetermined rotation to a recording medium being back-fed. It is an object of the present invention to provide a thermal transfer printer capable of improving the conveyance accuracy of a recording medium by applying a conveyance load and reducing the difference in the conveyance load applied to the recording medium between printing and non-printing. .
[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 a thermal head comprising: A rotatable platen roller capable of pressing against the recording medium, a torque biasing member capable of biasing a predetermined rotational load is disposed on the platen roller, and the image is printed on the recording medium. During printing, the recording medium pressed between the thermal head and the platen roller is pulled by the paper feed roller, and after printing is completed, the pressure contact is released to move the recording medium in a direction opposite to the drawing direction. Back feed, the platen roller rotates against the predetermined rotational load by the torque urging member, and the predetermined transport to the recording medium at the time of the back feed. Wherein the load is to be applied.
[0011]
Further, the torque biasing member comprises a friction member capable of biasing the platen roller with friction.
[0012]
Further, the torque biasing member includes a coil spring inserted and supported on a rotation shaft of the platen roller, and the coil spring elastically biases a side surface of the platen roller.
[0013]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the thermal transfer printer of the present invention will be described with reference to FIGS. 1 and 2 are schematic views for explaining a printing operation of the thermal transfer printer of the present invention, FIG. 3 is a schematic view when a recording medium is back-fed in the thermal transfer printer of the present invention, and FIG. 4 relates to the present invention. FIG. 4 is a schematic diagram illustrating a torque urging 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 on which a color image or the like can be printed. 2 and the driven roller 3 can be pressed and held. The recording medium 1 pressed and held between the paper feed roller 2 and the driven roller 3 is rotated in the clockwise direction or the counterclockwise direction by rotating the paper feed roller 2 in the arrow A direction or the arrow B direction. It can be reciprocated.
On the upstream side (right side in the drawing) of the paper feed roller 2 in the direction of arrow A, a rotatable platen roller 4 and a thermal head 5 that can be brought into contact with and separated from the platen roller 4, that is, can be moved up and down. Are arranged.
[0015]
The platen roller 4 is formed in a columnar shape and elongated in the direction perpendicular to the paper surface. To increase frictional resistance with the recording medium 1, a friction member (not shown) is formed on the outer peripheral surface of the platen roller 4 from rubber or the like. ) Is coated. 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 at a portion facing the platen roller 4.
The recording medium 1 pressed and held between the paper feed roller 2 and the driven roller 3 is moved between the platen roller 4 and the thermal head 5 in the head-up state in the transport direction of arrow A or the back feed of arrow B. It can be transported in any direction.
[0016]
An ink ribbon (not shown) having a width substantially equal to the width of the recording medium 1 is routed 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 equal to the area of one recording medium 1. Is repeatedly applied.
Further, a torque biasing member 6 capable of biasing a predetermined rotational load to the platen roller 4 is provided. As shown in FIG. 4, the torque biasing member 6 comprises a coil spring having a predetermined linear shape and a predetermined number of turns. The coil spring is inserted through and supported by the rotating shaft 4a of the platen roller 4, and is compressed and disposed between the side wall 7 of the main body case (not shown) and the side surface 4b of the platen roller 4.
For this purpose, the platen roller 4 has a side surface 4b elastically urged by a coil spring, which 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. And press it tightly.
The recording medium 1 can be fed to the paper feed roller 2 either from the right side of the paper feed roller 2 in the direction of arrow A or from the left side of the figure in the direction of arrow B.
The recording medium 1 fed between the paper feed roller 2 and the driven roller 3 is cueed by a paper detection sensor (not shown) detecting the front end 1a, and the paper feed roller 2 stops temporarily.
Thereafter, as shown in FIG. 2, the thermal head 5 is lowered, and the recording medium 1 and the ink ribbon are pressed against the platen roller 4.
[0018]
Next, the paper feed roller 2 is rotated in the counterclockwise direction to pull the recording medium 1 in the direction of arrow A, and selectively heats a plurality of heating elements of the thermal head 5 based on print information. The first color ink, for example, the Y color ink is thermally transferred to the printing surface 1b of the recording medium 1 to print the Y color image.
At the time of printing, the pressure applied to the thermal head 5 is set so that the transport load of the recording medium 1 pulled by the paper feed roller 2 and the driven roller 3 in the direction of arrow A becomes approximately 1 kgf, which is 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 is released. 2 is turned clockwise, and the recording medium 1 during non-printing is back-fed in the direction of arrow B.
Then, when the recording medium 1 is back-fed to the cueing position, cueing is performed again, and then M color ink is overprinted on the first Y color image. Thereafter, the same printing operation is repeated, and the C color and the K color inks are overprinted, whereby a color image of a desired color is printed on the recording medium 1.
[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 recording medium 1 is back-fed by rotating the platen roller 4 against a predetermined rotational load by the torque urging member 6.
The recording medium 1 that is back-fed in the direction of the arrow B is applied with a transport load of about 200 gf, which is at least twice as large as that in the related art.
[0021]
By applying a greater transport load than before to the recording medium 1 that is back-fed in the direction of the arrow B, the thermal head 5 is moved down during the printing operation, and the thermal head 5 is moved up during the printing operation. As a result, the difference in the transport load applied to the recording medium 1 during back-feeding during non-printing can be reduced.
Therefore, the conveyance accuracy of the recording medium 1 during the printing operation can be improved.
[0022]
Further, as another method for increasing the transport load of the recording medium 1 during the back feed, while the rotation of the platen roller 4 is stopped while the recording medium 1 is being back fed, the recording medium is attached to the outer peripheral surface of the platen roller 4. A method of making the sliding contact with each other is also conceivable. However, according to this method, since the outer peripheral surface of the platen roller 4 is coated with rubber or the like having a large frictional resistance, the recording medium 1 cannot be smoothly slid, and the recording medium 1 is intermittently fed. However, there is a possibility that the transfer accuracy is reduced.
[0023]
In the embodiment of the present invention, the head down operation is 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 that. Further, in the embodiment of the present invention, the torque urging member 6 has been described as a coil spring, but the torque urging member 6 includes a friction clutch (not shown) or the like disposed on the rotating shaft 4a of the platen roller 4. And a predetermined rotational load may be applied to the platen roller 4.
That is, the torque urging member 6 only needs to be capable of urging the platen roller 4 with a predetermined rotational load.
[0024]
【The invention's effect】
As described above, in the thermal transfer printer of the present invention, the platen roller rotates against a predetermined rotational load by the torque urging member by back-feeding the recording medium in the direction opposite to the pulling direction. Since a predetermined transport load is applied to the recording medium, the difference between the transport load of the recording medium applied during printing and the time of back feed which is non-printing can be reduced, and the recording during printing operation can be performed. The accuracy of transporting the medium can be improved.
For this reason, when printing a color image, it is possible to eliminate the printing deviation when the ink of the ink ribbon is overprinted, and to print a high-quality color image.
[0025]
Further, since the torque urging member is made of a friction member capable of urging friction with the platen roller, an appropriate friction member can be properly used according to the friction urging force, and the degree of freedom in design can be improved.
[0026]
Also, the torque biasing member is formed of a coil spring inserted and supported on the rotation shaft of the platen roller, and the coil spring elastically biases the side surface of the platen roller, thereby providing a thermal transfer printer having a simple structure and capable of reducing costs. 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 diagram when a recording medium is back-fed in the thermal transfer printer of the present invention.
FIG. 4 is a schematic diagram illustrating a torque urging member of a platen roller according to the present invention.
[Explanation of symbols]
REFERENCE SIGNS LIST 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 rotatable platen roller capable of pressing the thermal head through the recording medium. The platen roller is provided with a torque biasing member capable of biasing a predetermined rotational load, and the printing press pressed between the thermal head and the platen roller during printing of the image on the recording medium. The medium is pulled by the paper feed roller, and after printing is completed, the pressure contact is released and the recording medium is back-fed in a direction opposite to the pulling direction, so that the recording medium is subjected to the predetermined rotational load by the torque urging member. A thermal transfer printer, wherein the platen roller rotates to apply a predetermined transport load to the recording medium during the back feed. 2. The thermal transfer printer according to claim 1, wherein said torque urging member comprises a friction member capable of urging the platen roller. 3. The thermal transfer device according to claim 1, wherein the torque biasing member includes a coil spring inserted and supported on a rotation shaft of the platen roller, and the coil spring elastically biases a side surface of the platen roller. Printer.

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