JPH0557112B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thermal transfer color printer that records information on paper using a thermal head and an ink sheet.

Conventional configuration and its problems In thermal transfer printers that obtain color records by overlapping colors, in order to obtain good image quality without color shift, it is necessary to ensure the head alignment of each color. Of course, it is even more important to wind up the ink sheet stably so that the recording paper does not expand, contract, or skew while recording one color.

Fig. 1 is a schematic diagram of a conventional thermal transfer color printer. An ink sheet 1 coated with cyan) is prepared, and this ink sheet 1 is superimposed on a recording paper 2 and is pressed and held on a platen 4 by a thermal head 3. At the same time as applying the recording signal for the first color to the thermal head 3, the platen 4 is rotated in the direction of arrow A to print the recording paper 2.
By running the ink sheet 1, recording of the first color is performed. After the recording of the first color is completed, the thermal head 1 is moved away from the platen 4, the recording paper 2 is conveyed to the same recording start position as that of the first color, and the ink sheet 1 is conveyed to the beginning of the second color. Recording paper 2
When the respective cue operations for the ink film 1 are completed, the thermal head 3 presses the recording paper 2 and the ink film 1 again, and recording of the second color is started. A color recording is obtained by repeating the same operation for each color.

Normally, a back tension F _B and a winding tension F _W are added to the ink sheet 1 so that the ink sheet 1 runs stably without skew both during recording and during air feeding. F _B and
F _W are torque limiters 7 and 8 provided coaxially on the ink sheet supply reel 5 and take-up reel 6, respectively.
(The respective torque capacities are T _B and T _W. ) By the way, as the ink sheet 1 travels, the winding radius of both the supply reel 5 and the take-up reel 6 changes, so F _B ,
_FW changes. Figure 2 shows the ink sheet of a conventional thermal transfer printer from the beginning to the end.
This shows the changes in F _B and F _W , and the settings of T _W and T _B are set according to the winding tension F _We and back at the end of winding so that winding is always possible even when the ink sheet is being fed empty. The tension F _Be is set so that F _Be < F _We . Therefore, the winding tension at the beginning of winding
F _Wi and back tension F _Bi become F _Bi ≪F _We .

However, the above configuration has the following drawbacks. That is, the portion of the ink sheet 1 heated by the thermal head 3 undergoes thermal deformation, so that wrinkles may occur between the portion and the non-recorded portion, and depending on the recording pattern, one-sided elongation may occur. Ink sheet 1 transformed in this way is
Winding with _FW causes adverse effects such as uneven recording pitch and skew on the recording paper 2 during recording.
Recording quality deteriorates. Particularly in color printers, when colors are superimposed, color misregistration occurs, resulting in a significant drop in resolution. Furthermore, the larger the winding radius of the ink sheet 1 that is first loaded onto the supply reel 5, the greater the problem described above, which limits the number of ink sheets 1 that can be loaded at one time.

Purpose of the invention The present invention solves the above-mentioned conventional problems.
By setting the winding force of the ink sheet to a weak force during recording and a strong force during air feeding,
The purpose of the present invention is to provide a thermal transfer type color printer that can always wind up an ink sheet stably and obtain high-quality color recording without positional deviation.

Structure of the Invention The present invention comprises an ink sheet coated with thermal transferable ink, a thermal head that selectively generates heat from a heating element, a platen that faces the thermal head and presses and holds a recording paper and an ink sheet, and a thermal head. The printer is equipped with a drive device that presses or separates the ink sheet from the platen, a sheet winding device that winds up the ink sheet, and a head position detection device that detects whether the thermal head is pressed or separated. This is a thermal transfer color printer that is configured so that the sheet winding force when the thermal head is separated is greater than the sheet winding force when the thermal head is pressed. Because it is possible to wind up the ink sheet stably,
This can prevent color misalignment when superimposing colors.

DESCRIPTION OF EMBODIMENTS FIGS. 3 and 4 are schematic configuration diagrams of a thermal transfer color printer according to an embodiment of the present invention.
The same parts as in the figures are given the same reference numerals. In Figures 3 and 4, reference numeral 1 denotes an ink sheet in which heat-melting or heat-sublimating ink is applied on a thin base material in the order of overlapping colors, and this ink sheet 1 is wound up from a supply reel 5. It is wound so as to run on the reel 6. 7 is a torque limiter installed coaxially with the supply reel, and its torque capacity is
Back tension F _B to ink sheet 1 by T _B
give. 9 is a torque motor installed coaxially with the take-up reel 6, and its torque capacity T _W is determined by constant torque circuits C _L and C _W in the control circuit 11 as T _WL and T _WH.
(T _WL < T _WH ), and the winding force F _W of the ink sheet 1 also changes accordingly to two stages: F _WL and F _WH (F _WL < F _WH ). . 3 is a thermal head, and the thermal head 3 is driven by a platen 4 by a head drive device (not shown).
It is driven into a pressed state and a separated state. 10
is a head position detecting means constituted by a reflective photo sensor or the like, which detects when the thermal head 3 is in a pressed state and when it is in a separated state, and the detection results are inputted to the control circuit 11.
The torque capacity of the torque motor 9 is adjusted according to the detection result.
It is designed to switch between T _WL and T _WH .

The operation of the thermal transfer type color printer of this embodiment configured as described above will be explained below.

FIG. 3 is a diagram showing the recording state. In FIG. 3, the ink sheet 1 and recording paper 2 are pressed by the thermal head 3, and the platen 4 is rotated in the direction of arrow A while sending a recording signal to the thermal head 3. At the same time, the ink sheet 1 sent out by the rotation of the platen 4 is wound onto the take-up reel 6, thereby recording the first color.

If the winding force of the ink sheet 1 at this time is set to a light force F _WL (acted by T _WL ) that is enough to prevent the ink sheet 1 after recording fed out by the rotation of the platen 4 from sagging. Since the recording paper 2 is stably conveyed in synchronization with the rotation of the platen 4 without being affected by the winding force of the deformed ink sheet 1 after recording, uneven recording pitch and skew do not occur. FIG. 4 shows a state in which the thermal head 3 is separated from the platen 4 by a head drive device (not shown) after the recording of the first color is completed. In FIG. In order to detect that the ink sheet 1 has separated, the winding force of the ink sheet 1 is changed from F _WL to enough to overcome the back tension F _B.
The winding force F _WH that can be air-fed (acted by T _WL )
Switch to . The ink sheet 1 is continuously fed to the cue position for the second color by _FWH . During this time, the recording paper 2 is also conveyed to the recording start position for the first color.
When the respective cue operations for the recording paper 2 and the ink sheet 1 are completed, the thermal head 3 is again driven by a head drive device (not shown) to press the recording paper 2 and the ink sheet 1 against the platen 4.
At this time, the head position detection means 10 changes the winding force F _W of the ink sheet 1 again to F _WH in order to detect that the thermal head is pressing the platen 4.
to F _WL . From this state, the recording signal for the second color is applied to the thermal head 3, and the recording for the second color is performed in the same manner as for the first color. If you want to obtain a three-color record, repeat the above recording operation three times.

As described above, according to this embodiment, by setting the sheet winding force when the thermal head is separated to be larger than the sheet winding force when the thermal head is press-recording, the ink sheet can always be wound stably. This makes it possible to obtain color recording without color shift. Further, since the sheet winding force is switched in conjunction with the head position detection means for detecting the pressed state or the separated state of the thermal head, the winding force of the ink sheet can be reliably controlled.

Effects of the Invention The thermal transfer type color printer of the present invention is equipped with a head position detection means for detecting whether the thermal head is in a pressed state or a spaced state from the platen, and is linked to the head position detection means to detect when the thermal head is separated from the platen. By configuring the sheet winding force of the ink sheet to be larger than the sheet winding force when the thermal head is press recording, the ink sheet can be rolled up even when the thermal head is press recording and when the thermal head is separated. Since it is possible to consistently wind the ink sheet stably with an appropriate force, the recording paper during recording can obtain a stable pixel pitch without being affected by the unbalanced winding force caused by the deformed ink sheet after recording. . Moreover, since the winding force of the ink sheet is changed according to the pressing state of the thermal head, the winding force of the ink sheet can be reliably controlled. In other words, high-quality color recording without any color shift when colors are superimposed can be achieved with a simple configuration, so the practical effect is great.

In addition, regardless of the size of the winding radius of the ink sheet loaded on the supply reel, the ink sheet can always be wound with a stable winding force, making it possible to increase the number of ink sheets that can be loaded at one time. This has the effect of realizing a maintenance-free thermal transfer color printer.

[Brief explanation of drawings]

Figure 1 is a schematic configuration diagram of a conventional thermal transfer color printer, and Figure 2 is a characteristic diagram showing changes in winding force and back tension of an ink sheet from the beginning of winding to the end of winding of a conventional heat transfer color printer. , 3 and 4 are schematic diagrams of a thermal transfer color printer according to an embodiment of the present invention. 1... Ink sheet, 2... Recording paper, 3... Thermal head, 4... Platen, 5... Supply reel, 6... Take-up reel, 7, 8... Torque limiter, 9... Torque motor , 10... head position detection sensor, 11... control circuit.

Claims (1)

[Scope of Claims] 1. An ink sheet coated with thermally transferable ink, a thermal head that selectively generates heat from a heating element, a platen that faces the thermal head and presses and holds the recording paper and the ink sheet; A head driving device that presses or separates the thermal head from the platen, a sheet winding device that winds up the ink sheet, and a sheet winding force of the winding device depending on the positional relationship between the thermal head and the platen. sheet winding force switching means for switching the magnitude of the sheet winding force, and the sheet winding switching means changes the winding force of the sheet winding device when the thermal head is pressing against the platen to A thermal transfer type color printer characterized in that the winding force is smaller than the winding force when the ink sheet is spaced apart from the platen to an extent that does not cause deformation of the ink sheet. 2. Head position detection means for detecting whether the thermal head is in a pressed state or a separated state with respect to the platen is provided, and based on the output of the head position detection means, the sheet winding force switching means controls the sheet winding force of the winding device. The thermal transfer color printer according to claim 1, characterized in that the magnitude of the winding force is switched.