JP2006315237A - Thermal printer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermal transfer printer for printing a high quality image by stabilizing the traveling state of a recording member and an ink ribbon. <P>SOLUTION: The thermal printer comprises a thermal print head having a plurality of heating elements for printing a desired image on a recording member, and print data for generating heat selectively from the heating elements according to a desired image during print operation of the thermal print head. During print operation, the desired image is printed on the recording member by applying predetermined energy selectively to the heating elements based on the print data, and disturbance of image due to variation in print speed is reduced by performing density correction of print speed variation caused by the number of conducting heating elements or the gradation. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thermal printer, and more particularly to a printer that can reduce the influence of a change in printing speed during recording and obtain a high-quality printed image.

  Conventional thermal transfer printers have a platen roller and a thermal print head that presses against the platen roller. The recording member and an ink ribbon are sandwiched between the platen roller and the thermal print head and the platen roller is rotated. In this way, the recording member and the ink ribbon are fed. In addition, there is also a method in which the recording member is fed between two opposed rollers.

In such conventional thermal transfer printer printing, a predetermined image is selectively applied to a plurality of heating elements based on print data on a recording member to cause the heating elements to generate heat, and the ink on the ink ribbon is sublimated. Alternatively, it is melted and a desired image is transferred to the recording member.
JP-A-5-345428

  However, in the conventional thermal transfer printer as described above, when a desired image is printed on a recording member, the ink in a portion where predetermined energy is applied to the heating element based on the print data is sublimated or melted. The portion where no energy is applied to the ink is in a state where the ink is solidified without melting. For this reason, the ink ribbon back surface temperature is greatly different between a portion to which predetermined energy is applied and a portion to which no energy is applied. On the other hand, the friction coefficient on the back side of the ink ribbon often changes greatly depending on the temperature. Due to the load fluctuation caused by the change of the friction coefficient, the recording member and the ribbon running during the printing operation become unstable, and the print quality of the image may deteriorate. It was. SUMMARY OF THE INVENTION It is an object of the present invention to provide a thermal transfer printer that solves the above-described problems and corrects image disturbance due to a change in friction coefficient between a recording member and an ink ribbon and can print a high-quality image. And

  In order to solve the above problems, a thermal transfer printer of the present invention includes a thermal print head having a plurality of heating elements for printing a desired image on a recording member, and the heat generation according to the desired image during a printing operation of the thermal print head. Printing data for selectively heating the element, and during the printing operation, a predetermined energy is selectively applied to the heating element based on the print data to print the desired image on a recording member; The density of the change in the printing speed caused by the number of heating elements to be energized and the gradation is corrected to reduce image disturbance due to the change in the printing speed.

  The thermal transfer printer according to the present invention prints a desired image on a recording member by selectively applying predetermined energy to a heating element based on print data during a printing operation, and the number of heating elements to which the predetermined energy is applied. Since the density change due to the change in the printing speed is corrected according to the gradation, it is possible to obtain a high-quality image free from printing unevenness.

The embodiment of the thermal transfer printer of the present invention will be described below.
A schematic configuration of a roll paper printing apparatus according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, a paper holder unit 2 is attached to the frame 1 so that the printing paper 8 and the ink ribbon 19 can be easily replaced. Further, the paper holder unit 2 is provided with a paper discharge port 2a, and a paper receiving pocket 4 for receiving cut scraps of the print paper 8 discharged from the paper discharge port 2a is attached to be openable and closable. As shown in FIG. 2, the printing paper 8 and the ink ribbon 19 can be easily attached and detached by opening the paper holder unit 2.

  The main configuration of the roll paper printing apparatus shown in FIG. 1 will be described with reference to FIG. A paper holder unit 2 is rotatably attached to the frame 1 by a paper holder unit shaft 2b, and can be turned between a closed state shown in FIG. 1 and an open state shown in FIG. ing. A paper winding shaft 7 is rotatably attached to the paper holder unit frame 3 constituting the frame of the paper holder unit 2, and the printing paper 8 wound in a roll shape is mounted on the paper winding shaft 7. ing. Further, the lower grip roller 9 and the upper grip roller 10 are rotatably attached to the paper holder unit frame 3 so as to sandwich the printing paper 8 passing between them. A platen 11 is rotatably mounted adjacent to the lower grip roller 9 and the upper grip roller 10.

  A feed roller 12 for conveying the printing paper 8 is rotatably mounted adjacent to the platen 11, the feed roller 12 is connected to a transmission means 22 described later, and the transmission means 22 is connected to a paper conveyance motor 21 which is a driving means. The paper transport motor 21 is connected to a control circuit (not shown). A pinch roller 13 is rotatably attached to the outer peripheral upper surface of the feed roller 12 so as to sandwich the printing paper 8 between the feed roller 12 and the pinch roller 13. A paper guide plate 14 for guiding the printing paper 8 from the feed roller 12 to the paper discharge port 2a is provided between the feed roller 12 and the paper discharge port 2a. A first roller holder 15 and a second roller holder 17 are provided with a passage for the paper 8 passing therethrough.

  The end 8a of the printing paper 8 wound around the paper winding shaft 7 is pulled out, passes between the lower grip roller 9 and the upper grip roller 10, and is wound around a part of the outer periphery of the platen 11 to feed the feed roller 12. Through the passage formed between the paper guide plate 14, the first roller holder 15, the curl correction roller 16, and the second roller holder 17 from the paper discharge port 2a. It is mounted to be discharged.

  Further, an ink ribbon winding shaft 18 is rotatably attached to the paper holder unit frame 3, and an ink ribbon 19 wound in a roll shape is attached to the ink ribbon winding shaft 18. An ink ribbon winding shaft 20 is rotatably attached to the opposite side of the platen 11 from the ink ribbon winding shaft 18. The ink ribbon mounted on the ink ribbon winding shaft 18 is attached to the ink ribbon winding shaft 20. The end of 19 is pulled out and attached so that it can be wound up. Yellow, magenta, and cyan inks are sequentially and repeatedly applied to the ink ribbon 19 with predetermined areas.

  A state when the thermal print head 6 performs printing on the printing paper 8 will be described with reference to FIG. A thermal print head holder unit 5 to which a thermal print head 6 is fixed at the tip is attached to the frame 1 so as to be rotatable by a thermal print head holder unit shaft 5a. The thermal print head 6 is rotated from the standby position shown in FIG. 3 by the thermal print head holder unit driving means (not shown), and the thermal print head 6 overlaps the ink ribbon 19 and the printing paper 8 as shown in FIG. Press contact.

  Printing with the thermal print head 6 is performed while the printing paper 8 is being conveyed by the first guide roller 16 and the second guide roller 19, and the printing paper 8 is conveyed as follows. The printing paper 8 extending from the paper winding shaft 7 between the lower grip roller 9 and the upper grip roller 10 is supported by the upper surface of the platen 11 and is sandwiched between the feed roller 12 and the pinch roller 13. The paper is guided by the first guide roller 16 and the second guide roller 19 so as to pass through between the paper guide plate 14 and the first roller holder 15 and the second roller holder 18 and be discharged from the paper discharge port 2a. Yes. In this state, color printing is performed by sequentially printing yellow, magenta, and cyan on the printing paper 8 while reciprocating the printing paper 8 appropriately.

FIG. 5 shows the positional relationship between the thermal print head 6 and the platen 11 in a printing state.
During printing, the thermal print head 6 is pressed against the platen 11 and desired printing is performed while energizing the heating element of the thermal print head 6.

When the conveyance amount of the printing paper is measured when the number of energized dots to the thermal print head 6 is large and small, the printing paper is fed to the nipping portion between the feed roller 12 and the pinch roller 13 at a set feeding speed. However, when the number of energized dots is large in the thermal print head 6 and the platen 11 portion, or when the print density is high and the energization energy to the thermal print head 6 is large, the frictional resistance of the ink ribbon increases, so the printing speed becomes slow. It was found that the print density was high.
Such a change in the feeding speed of the printing portion of the platen 11 causes streak-like printing unevenness in the direction of the heating element line of the thermal print head 6 on the printing paper.
In order to eliminate the above-described printing unevenness, the total amount of heat applied to one line is calculated in advance from the number of energized dots per line and gradation, and when the amount of heat applied to one line is large, the printing speed is reduced. In consideration of this, the amount of heat applied to one line is corrected to be uniformly reduced by several percent. On the other hand, when the total amount of heat applied to one line is small, the amount of heat applied to one line is corrected to be uniformly increased by several percent in consideration of the increase in printing speed. As a result, the change in the print density due to the change in the printing speed can be corrected, so that high-quality printing without causing printing unevenness can be performed.
In this embodiment, the correction is performed in consideration of the fluctuation of the frictional resistance of the ink ribbon, but the printing density can be corrected in consideration of the fluctuation of the frictional resistance of the recording paper.

1 is a perspective view showing an appearance of a roll paper printing apparatus in an embodiment according to the present invention. It is a perspective view which shows the state which opened the paper holder unit 2 of the roll paper printing apparatus shown in FIG. FIG. 2 is a main cross-sectional view illustrating a state of a main cross section of the roll paper printing apparatus illustrated in FIG. 1. It is operation | movement explanatory drawing which shows the state in which the print head 6 in the roll paper printing apparatus shown in FIG. 3 can print. It is operation | movement explanatory drawing which shows the operation | movement principle of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Frame 2 Paper holder unit 2a Paper discharge port 2b Paper holder unit axis 3 Paper holder unit frame 4 Paper receiving pocket 5 Print head holder unit 5a Print head holder unit axis 6 Print head 7 Paper holder 8 Printing paper 8a Paper edge 9 lower grip roller 10 upper grip roller 11 platen 12 feed roller 13 pinch roller 14 paper guide plate 15 first roller holder 16 curl correction roller 17 second roller holder 18 ink ribbon winding shaft 19 ink ribbon 20 ink ribbon winding shaft 21 Paper transport motor 22 Transmission means 23 Feed roller shaft 24 Clutch shaft 25 First slip clutch plate 26 Second slip clutch plate

Claims (1)

  A thermal print head having a plurality of heating elements for printing a desired image on a recording member; and print data for selectively heating the heating elements according to the desired image during a printing operation of the thermal print head; During the printing operation, a predetermined energy is selectively applied to the heating element based on the print data to print the desired image on the recording member, and a printing speed change caused by the number of heating elements to be energized and gradation. A thermal printer characterized in that image density is corrected to reduce image disturbance due to changes in printing speed.

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