JPH05124322A - Heat transfer printer - Google Patents

Abstract

PURPOSE:To stabilize the printing quality of heat transfer ribbon by a method wherein the tension of the ribbon during printing is stably maintained by controlling the torque of the driving motor of a wind-up roll is response to the output of the detected change of the ribbon wind-up roll diameter with a ribbon wind-up roll diameter detector. CONSTITUTION:When heat transfer ribbon 3 is wound by a ribbon winding roll 5, the change of the roll diameter of the roll 5 is detected with a ribbon wind-up roll diameter detector. After that, at a torque controlling section 10, the torque of the driving motor 7 of the roll 5 is controlled in response to said torque detection output so as to stably maintain the tension of the ribbon 3 during printing. Thus, the printing quality of the heat transfer ribbon is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal transfer printer, and more particularly to a thermal transfer ribbon drive control mechanism for improving print quality, and is particularly effective for a line head type thermal transfer printer.

[0002]

1) For example, the output of a motor for winding a thermal transfer ribbon in a line head type thermal transfer printer is
It is constant from the beginning to the end of winding, and at the beginning and the end of winding, the winding torque varies due to the difference in the diameter of the wound ribbon, the tension of the thermal transfer ribbon changes, and the print quality changes. It could have an adverse effect.

2) Due to the change in tension accompanying winding, the range of the amount of winding of the ribbon is limited, and it is inconvenient to use a ribbon having a large long roll.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal transfer printer capable of controlling the tension of a thermal transfer ribbon and maintaining stable printing quality.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a ribbon take-up roll for correcting fluctuations in the tension of the thermal transfer ribbon in an apparatus for performing thermal transfer printing by winding a thermal transfer ribbon with a ribbon take-up roll and running it together with a recording sheet. A thermal transfer printer having a driving force control means, further means for detecting the winding amount of the thermal transfer ribbon or the diameter of the ribbon winding roll, and controlling the driving force of the ribbon winding roll according to the detection output. Having a control means,
The ribbon roll diameter detecting means also has a configuration in which it is provided with a lever mechanism that follows changes in the outer diameter of the roll diameter and means that generates a signal according to the displacement of the lever.

Specifically, means for winding the thermal transfer ribbon and means for controlling the winding torque according to the winding amount (roll diameter) of the thermal transfer ribbon are provided, and the winding amount (diameter) for the thermal transfer ribbon is set. Therefore, when the winding amount is small (when the diameter is small), the torque of the winding motor is low,
Control means is provided to increase the torque of the winding motor as the winding amount increases (the diameter increases).

[0007]

Since the diameter of the ribbon take-up roll increases as the ribbon is used, if the drive torque of the ribbon take-up roll is constant, the tension of the running ribbon will gradually increase according to the ribbon take-up amount. However, in the present invention, the take-up torque of the take-up roll is automatically changed according to the change in the take-up amount (roll diameter) of the thermal transfer ribbon due to printing. When the ribbon winding amount is small (roll diameter is small), the winding motor torque is reduced.
As the winding amount increases (the roll diameter increases), the torque is increased, the tension change of the ribbon is corrected, and the tension is maintained substantially constant during printing, so that good print quality can be maintained. Therefore, the ribbon can be effectively used over a wide range of the winding roll diameter.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of the main part of a line head type thermal transfer printer according to one embodiment of the present invention. (1) is a printing / recording section, and (2) is a recording sheet run by a separate sheet feeding mechanism. is there. Reference numeral (3) is a ribbon for thermal transfer, which is taken up by a ribbon take-up roll (5) from a ribbon supply roll (4) through a print recording section (1) as the printing progresses.

Reference numeral (6) is a ribbon winding drive motor for driving the ribbon winding roll (5), which is energized by the motor power source (9). (10) is a torque control unit for controlling the torque of the ribbon winding drive motor (7),
(11) is a ribbon take-up roll diameter detector for detecting the outer diameter of the ribbon take-up roll (5) at every moment. During printing, the motor (7) responds to the change (increase) in the outer diameter of the ribbon take-up roll detected by the detector (11).
The output of the power supply (9) is controlled by the torque control unit (10) so that the drive torque of the power source (9) is controlled (increased) and the tension of the ribbon (4) is maintained substantially constant.

This driving torque is preferably controlled so that the torque value is proportional to the outer diameter of the ribbon winding roll (5) and the tension of the thermal transfer ribbon is kept constant or within a set value range. It is also possible to control the torque stepwise such that the torque is increased by a fixed amount each time the roll diameter is increased by a predetermined amount. Therefore, the torque control unit (1
0), a memory storing a CPU and a torque control program, a communication interface, etc. may be provided and configured to be computer-controlled.

FIG. 2 shows an example of the mechanical structure of the main part of the device of the present invention, particularly the ribbon winding roll diameter detector (11).
(A) shows the initial state of ribbon use, and (b) shows the state where the ribbon is almost consumed. The detector (11) is, for example, a lever mechanism (11a) loaded so as to follow a change in the outer diameter of the ribbon winding roll (5), a load member (not shown) such as a spring, a lever displacement or It is composed of a converter (11b) which generates an output electric signal according to the rotation amount.

Reference numeral (12) is a thermal head, (13) is a platen roll, and (14) and (15) are rollers. FIG. 3 shows a specific example of the structure of the detector (11). The rotary displacement (115) of the volume resistance type electric displacement (113) mounted on the holding plate (114) is attached to the rotary lever ( 111) is attached, and the lever (111) is always pressed by the spring (112) in a direction (clockwise direction in the figure) to follow the outer diameter surface of the ribbon winding roll (5). A signal corresponding to the roll diameter can be obtained as the output signal of the volume resistor (113), but if necessary, a function resistor for converting the output signal of the resistor (113) into an output signal proportional to the roll diameter or a linear relation output signal. Etc. may be used.

With the configuration as shown in FIG. 3, instead of directly detecting the tension of the thermal transfer ribbon, this can be indirectly obtained by a simple mechanism via the ribbon winding amount (winding roll diameter). Reference numeral (101) is a torque control board on which each element of the torque control unit (10) is mounted, and the torque of the ribbon winding drive motor is controlled as described above according to the output of the detector (11). The torque control board (101) may also be provided with the power source (9).

In the above, the outer diameter of the thermal transfer ribbon take-up roll is detected, and the driving force of the ribbon take-up roll is controlled based on this detection signal. However, in some cases, the ribbon winding amount is detected. Device and winding amount integration mechanism, and the change in the diameter of the ribbon winding roll based on this (when the roll core is small, the ribbon winding roll diameter is approximately proportional to the square root of the ribbon winding integrated value)
It is also possible to provide a computing mechanism for calculating and to control the driving force of the winding roll.

According to the present invention, as outlined above,
Even if the roll diameter changes gradually based on the change in the ribbon winding amount (roll outer diameter) that accompanies printing, the tension of the thermal transfer ribbon is maintained almost constant during printing. It is possible to eliminate various problems such as adverse effects on printing due to fluctuations in the print quality, such as print blurring and print position deviation.

[0016]

As described above, according to the present invention, the following effects can be obtained. 1) Since the fluctuation of the tension of the thermal transfer ribbon is effectively corrected and is maintained substantially constant or within the required range, the adverse effect on the print quality due to the fluctuation of the tension is prevented. Therefore, it is possible to maintain high print quality over a wide range of roll diameter.

2) The ribbon tension does not fluctuate and the range of the ribbon winding amount is not limited. Therefore, a large roll (long) ribbon can be used while maintaining the print quality. Also, since a core with a smaller diameter can be used, the effective length of the ribbon can be made larger for the same roll outer diameter. Therefore, it is possible to reduce the frequency of ribbon replacement and reduce the labor and time. Furthermore, the volume of the ribbon, which requires a considerably large proportion of the entire printing device, can be reduced, which is also effective in downsizing the printing device.

3) Instead of directly detecting the tension of the ribbon, the outer diameter value of the ribbon winding roll is indirectly detected by a simple mechanism such as a follower lever, so that the ribbon tension control mechanism can be simply constructed.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of a thermal transfer printer according to an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration example of a main part of the apparatus of FIG. 1, particularly a winding rule diameter detecting part.

FIG. 3 is a diagram showing a specific configuration example of FIG.

[Explanation of symbols]

 1 Print Recording Section 2 Recording Paper 3 Thermal Transfer Ribbon 4 Ribbon Supply Roll 5 Ribbon Winding Roll 6 Transmission Mechanism 7 Ribbon Winding Drive Motor 8 Motor Power 9 Motor Power 10 Torque Control 11 Ribbon Winding Roll Diameter Detector 11a Lever 11b Displacement・ Electrical converter 12 Thermal head 13 Platen roll 14 Roller 15 Roller 111 Rotating lever 112 Spring 113 Volume resistor

Claims (3)

[Claims] 1. An apparatus for performing printing by running a thermal transfer ribbon together with a winding recording sheet by means of a ribbon take-up roll, wherein a ribbon take-up roll driving force control means for correcting fluctuations in the tension of the thermal transfer ribbon is provided. And thermal transfer printer. 2. A means for detecting the winding amount of the thermal transfer ribbon or the diameter of the ribbon winding roll, and a control means for controlling the driving force of the ribbon winding roll according to the detection output. The thermal transfer printer according to claim 1. 3. A ribbon roll diameter detecting means is provided with a lever mechanism that follows changes in the outer diameter of the roll diameter and means for generating a signal according to the displacement of the lever. 2. The thermal transfer printer according to 2.