JP2001225537A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal printer that can prevent a tension of an ink ribbon from being raised when a head is moved downward and can efficiently perform high quality printing. SOLUTION: Before the printing on a printing medium P disposed on a platen 2 is started, a thermal head 24 is moved from a standby position to a printing position and a supply side ribbon winding reel 3 is driven to be rotated to supply the ink ribbon 17 and then a rotational angle of the supply side ribbon rewinding reel 3 necessary for holding a tension arm 31 on a predetermined adequate position is obtained. After that, the printer movers to a printing mode and feeds the ink ribbon by rotating the supply side ribbon winding reel 3 by the rotational angle obtained in the above operation before the thermal head 24 is moved downward by each movement of the thermal head 24 from the standby position to the printing position during the printing on one sheet of the printing medium P from the starting to the completion.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer, and more particularly, to a means for optimizing a tension acting on an ink ribbon during printing to improve print quality.

[0002]

2. Description of the Related Art In a thermal printer, a thermal head is pressed against a print medium via an ink ribbon carrying a heat-soluble solid ink on one side, and a heating element arranged in the thermal head is selectively heated. The desired characters, symbols, figures, and the like are printed by transferring the dissolved solid ink to a print medium.

Conventionally, as a thermal printer of this type, an ink ribbon wound around a reel is used as one suitable for mass printing, and one end of an ink ribbon pulled out from a supply-side ribbon winding reel is wound up. Winding on the side ribbon winding reel, the ink ribbon transport path from the supply side ribbon winding reel to the winding side ribbon winding reel,
There is a known one in which a thermal head and a platen are arranged to face each other via an ink ribbon. The thermal head is configured to be able to reciprocate in a direction approaching or separating from the platen, and is moved to a position in contact with the platen via an ink ribbon and a print medium during printing,
When printing is stopped, the print head is moved to a standby position separated from the platen.

In the thermal printer having such a configuration, it is necessary to always maintain the tension of the ink ribbon in an appropriate range in order to prevent slippage between the ink ribbon and the print medium and obtain good print quality. . As a method of applying a required tension to the ink ribbon, for example, as disclosed in Japanese Patent Application Laid-Open No. 6-64266, a drive motor is provided on a take-up ribbon winding reel, and a torque of the drive motor is used. And a drive motor on both the supply-side ribbon winding reel and the take-up ribbon winding reel, as disclosed in, for example, JP-A-7-251517.
There is a method of applying the torque of each of these drive motors to the ink ribbon. Further, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 6-64266, a thermal printer having the above-mentioned configuration, which is well known, has a tension urged in a predetermined direction by a spring on a transport path of an ink ribbon. It is also known that an arm is arranged to stabilize the tension acting on the ink ribbon by the tension arm.

Further, Japanese Patent Application Laid-Open No. 6-64266 discloses that a sensor detects the amount of winding (roll diameter) of an ink ribbon wound on a winding reel winding reel and detects the roll diameter. The rotation speed of the take-up ribbon winding reel is controlled so that the ink ribbon is wound up quickly when the roll diameter is large and slow when the roll diameter is large, so that the tension applied to the ink ribbon during printing is always appropriate. Techniques for controlling the operating range are also described.

On the other hand, Japanese Patent Application Laid-Open No. 7-251517 discloses a head-down operation to prevent an increase in the tension of the ink ribbon that occurs when the thermal head is moved from a standby position (up position) to a printing position (down position). During the period from the start of the thermal head to the contact of the thermal head with the platen, the ink ribbon is fed from the supply-side ribbon winding reel at a predetermined constant speed to prevent the tension from rising. A technique is described in which a reel driving motor is controlled so that the torque acting on the side ribbon winding reel and the winding side ribbon winding reel is constant, and the tension acting on the ink ribbon is maintained at an optimum value. .

[0007]

SUMMARY OF THE INVENTION However, Japanese Patent Laid-Open No.
The technology described in Japanese Patent No. 64266 discloses a variation in the tension of the ink ribbon that occurs in the transport path of the ink ribbon from the supply-side ribbon winding reel to the thermal head, especially when the thermal head is moved from the standby position to the printing position. No consideration is given to the means for preventing the rise of the tension of the ink ribbon in the transport path concerned, and both the supply-side ribbon winding reel and the take-up ribbon winding reel are provided with drive motors, and the supply-side ribbon winding reel is provided. Applicable to thermal printers of the type that adjusts the tension of the ink ribbon in the transport path of the ink ribbon from the spinning reel to the thermal head and in the transport path of the ink ribbon from the thermal head to the winding reel winding reel. Can not.

On the other hand, Japanese Patent Application Laid-Open No. 7-251517 describes a technique not described in the above-mentioned Japanese Patent Application Laid-Open No. 6-64266. However, the technology described in this publication has a configuration in which the thermal head is moved to a standby position in a non-printing area of print data, and the thermal head is moved to a printing position in a print area of the print data. Each time the area switches to the print area, set the target speed based on the amount of ink ribbon wound on the supply-side ribbon winding reel, and set the target speed within the period from the start of head down operation until the thermal head contacts the platen. The ink ribbon is fed from the supply-side ribbon winding reel at a predetermined constant speed, and thereafter, the changeover switch is switched so that the torque acting on the supply-side ribbon winding reel and the winding-side ribbon winding reel is constant. In order to repeat the procedure of controlling the drive motor, the reel drive motor and the changeover switch Large burden on the CPU that controls, there is a problem that it is difficult to perform the printing with high efficiency.

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned deficiencies of the prior art, and an object of the present invention is to prevent an increase in the tension of an ink ribbon which occurs in a process of moving a thermal head from a standby position to a printing position. It is an object of the present invention to provide a thermal printer which can solve the problem and can perform high quality printing with high efficiency.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a supply-side ribbon winding reel and a driving motor thereof, a winding-side ribbon winding reel and a driving motor thereof, and An ink ribbon pulled out from the side ribbon winding reel and wound on the winding side ribbon winding reel; a thermal head and a motor for driving the thermal head arranged reciprocally in a transport path of the ink ribbon; A platen arranged to face the thermal head, a tension arm slidably arranged in the ink ribbon transport path to apply a required tension to the ink ribbon, and a tension detector for detecting a tension acting on the ink ribbon Means, and a control unit for controlling the thermal head and each of the driving motors, and a mark supplied on the platen. Before starting printing on the medium, the thermal head is moved from the standby position separated from the platen to a printing position in contact with the platen via the ink ribbon and the print medium, and the thermal head is moved from the supply-side ribbon winding reel. The ink ribbon is fed out, and the rotation angle of the supply-side ribbon winding reel required to hold the tension arm at a predetermined appropriate position is determined, and then the thermal head is returned to the standby position, and Starting the printing on the printing medium after rotating the winding-side ribbon winding reel to return the tension of the ink ribbon to an initial state, and starting printing on the one printing medium until printing is completed, Each time the thermal head is moved from the standby position to the print position, the thermal head is moved down before the thermal head is lowered. The obtained the supply-side ribbon winding reel by the rotation angle corresponding to the angle of rotation and rotated in the feeding direction of the ink ribbon, characterized in that it held to a proper value the tension acting on the ink ribbon.

When the thermal head is moved from the standby position to the printing position, the ink ribbon is pressed toward the platen by the thermal head, so that the ink ribbon transport path becomes longer, and the tension acting on the ink ribbon increases. The tension arm is always urged in one direction by a spring, and is configured to apply tension to the ink ribbon by the elastic force of the spring. Swings in a direction to reduce the tension of the ink ribbon against the elastic force of
The transport path length of the ink ribbon is kept constant. However, as described above, since the tension arm is urged in one direction by the spring, the elastic force of the spring acting on the ink ribbon increases as the swing amount of the tension arm increases. Therefore,
Even if the transport path length of the ink ribbon is kept constant by the swing of the tension arm, the tension acting on the ink ribbon cannot be completely reduced, and the tension increases in proportion to the swing amount of the tension arm. Then, when the tension acting on the ink ribbon becomes larger than an appropriate value, a slip occurs between the ink ribbon and the print medium,
This is a factor that deteriorates print quality.

When the thermal head is moved from the standby position to the print position, the rotation angle of the supply-side ribbon winding reel required to hold the tension arm at a predetermined appropriate position is determined by the supply-side ribbon winding reel. It depends on the winding amount of the ink ribbon wound on the reel, that is, the roll diameter of the supply-side ribbon winding reel. When the roll diameter is large, the rotation angle is small, and when the roll diameter is small, the rotation is small. It is necessary to increase the angle. However, since the ink ribbon is very thin in units of micrometers, the amount of winding of the ink ribbon does not change so much when printing is performed on a single print medium, and the tension in practical use becomes excessively large, and the printing quality is increased. Does not deteriorate.

Therefore, before starting printing on one print medium, the rotation angle of the supply-side ribbon winding reel required to hold the tension arm at a predetermined appropriate position is determined. Every time the thermal head is moved from the standby position to the printing position, the supply-side ribbon winding reel is driven to rotate by a rotation angle corresponding to the rotation angle previously obtained before the thermal head is lowered, and the ink ribbon is fed. In addition, since the tension of the ink ribbon can always be regulated within a required appropriate range irrespective of the reciprocating movement of the thermal head, high-quality printing without uneven printing can be obtained. Further, when the rotation angle of the supply-side ribbon winding reel is obtained for each print medium, the rotation angle is obtained as compared with the case where the rotation angle of the supply-side ribbon winding reel is obtained each time the thermal head reciprocates. The number of calibration operations can be reduced, so that printing can be performed efficiently.

As a motor for driving the supply-side ribbon winding reel and the winding-side ribbon winding reel, any well-known motor can be applied, but low noise, low vibration, and low rotation unevenness. For this reason, an ultrasonic motor is particularly suitable.

The detecting means for detecting the tension acting on the ink ribbon may be a potentiometer for detecting the swing amount of the tension arm, a load cell for directly detecting the tension acting on the ink ribbon, or both of them. Can be prepared.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 to 4 are views showing a configuration around a head in a thermal printer according to an embodiment.
1 is a perspective view, FIG. 2 is a front view when the thermal head is at a standby position, FIG. 3 is a front view when the thermal head is at a printing position, and FIG. 4 is a plan view of a main part.

In these figures, 1 indicates a carriage base and 2 indicates a platen. Carriage base 1
Is mounted on a guide rail (not shown), and is reciprocated within the width of the print medium P along the platen 2 by the carriage drive motor 1a (see FIG. 6). The transfer means of the carriage base 1 using the guide rail and the drive motor is a matter belonging to the public domain and is not the gist of the present invention, so that the description is omitted. An optical or mechanical paper detecting unit 2a (see FIG. 6) for detecting the presence or absence of the print medium P supplied one by one on the platen is provided on or near the platen 2.

On the upper portion of the carriage base 1, a supply-side ribbon winding reel 3 and a winding-side ribbon winding reel 4 are arranged at a predetermined interval. Each of these reels 3,
4 is rotatably attached to the carriage base 1 via bearings 5 and 6, as shown in FIG. As shown in the drawing, brackets 7 and 8 are provided on the rear side of the carriage base 1, and the brackets 7 and 8 are provided with a drive motor 9 for the supply-side ribbon winding reel 3 and a winding-side ribbon winding. The drive motors 10 of the spinning reels 4 are individually mounted, and the main shafts of the motors 9 and 10 are connected to the supply-side ribbon winding reel 3 and the winding-side ribbon via couplings 11 and 12 having an eccentricity adjusting function. Each of the winding reels 4 is individually connected to the center axis. Each of the motors 9 and 10 is individually provided with a supply-side rotary encoder 15 and a take-up rotary encoder 16 each including a code plate 13 attached to the main shaft and a detection unit 14 attached to the brackets 7 and 8. It is attached and detects the rotation amount and rotation direction of each of the motors 9 and 10. The ink ribbon 17 pulled out from the supply-side ribbon winding reel 3 is wound around each roller group described later, and the other end is wound on the winding-side ribbon winding reel 4. As the motors 9 and 10, any known motor can be used, but an ultrasonic motor is particularly preferable because of its low noise, low vibration, and low rotation unevenness.

A thermal head transfer unit 21 is vertically movable between the supply ribbon winding reel 3 and the take-up ribbon winding reel 4 in the carriage base 1. A thermal head 24 is attached to a lower end portion of the thermal head via an attachment joint 22 and a head attachment base 23. The thermal head transfer unit 21 moves the thermal head 24 up and down with a required stroke, such as a head drive motor 24a (see FIG. 6) and a rack and pinion mechanism (not shown) that is driven to rotate by the motor. It is configured with a mechanism to do. When the above-described rack and pinion mechanism is used as the thermal head transfer unit 21, a thermal head 24 is attached to the lower end of the rack via an attachment joint 22 and a head attachment base 23. The thermal head 24 is located between a standby position separated from both the platen 2 and the ink ribbon 17 as shown in FIG. 2 and a printing position which is in contact with the platen 2 via the ink ribbon 17 as shown in FIG. It is reciprocated.

Below the supply-side ribbon winding reel 3 and the take-up ribbon winding reel 4 in the carriage base 1, a supply-side tension arm 31 and a take-up tension arm 32 are individually arranged. As shown in FIG. 5A, the supply-side tension arm 31 is formed in a crank shape with a main shaft 31a, an arm 31b, and a tape roller 31c, and the main shaft 31a is provided on the rear side of the carriage base 1. Bracket 31d
It is rotatably attached to. A tension spring 31e is stretched between the main shaft 31a and the bracket 31d, and constantly urges the tape roller 31c outward. As shown in FIGS. 1 to 3, the tape roller 31 c penetrates through an arc-shaped hole 18 formed in the carriage base 1, and the leading end is disposed on the front side of the carriage base 1. The supply-side tension arm 31 swings around the main shaft 31a in the directions of arrows A and B according to the change in the tension acting on the ink ribbon 17 wound around the tape roller 31c (FIG. 5). The swing amount and swing direction of the supply-side tension arm 31 are detected by a supply-side potentiometer 33 attached to the bracket 31d and having a movable portion connected to the main shaft 31a.

The winding-side tension arm 32 is also shown in FIG.
As shown in (b), except that the biasing direction of the arm by the tension spring is reversed, the supply-side tension arm 3
1 is configured. In FIG. 5B, 32a is a main shaft, 32b is an arm, 32c is a tape roller 32d, a bracket, 32e is a tension spring, and 34 is a winding-side potentiometer.

The torque of the winding-side tension arm 31 is applied to the ink ribbon 17 to the winding-side ribbon winding reel 4.
Is set higher than the torque of the supply-side tension arm 31 in order to secure the winding tightening force.

Below the supply-side tension arm 31 and the take-up tension arm 32 in the carriage base 1, a supply-side pinch roller 41 and a take-up-side pinch roller 42 are individually arranged. As shown in FIG. 1, the supply side pinch roller 41 is rotationally driven by a stepping motor 43 in a direction to pull back the ink ribbon 17 from the thermal head 24 side. The take-up side pinch roller 42 is also rotationally driven by a stepping motor 44 (see FIG. 6) in a direction to pull out the ink ribbon 17 from the thermal head 24 side. The torque of the take-up pinch roller 41 is set higher than the torque of the supply-side pinch roller 41 in order to apply a required tension to the ink ribbon 17 from the supply-side pinch roller 41 to the take-up pinch roller 42. You.

A supply-side load cell 45 and a take-up load cell 46 are provided between the supply-side pinch roller 41 and the thermal head 24 and between the take-up-side pinch roller 42 and the thermal head 24 at the lower end of the carriage base 1.
Are individually disposed, and a supply-side pressure receiving roller 47 and a winding-side pressure receiving roller 48 are individually set in the pressure receiving portions of the load cells 45 and 46, respectively.
Further, between the thermal head 24 and the take-up side load cell 46 at the lower end of the carriage base 1, FIG.
The peel angle adjusting roller 49 that engages with the ink ribbon 17 when the thermal head 24 is lowered as shown in FIG.

In addition, on the front surface of the carriage base 1,
A plurality (10 in this embodiment) of guide rollers 50a to 50
50j are rotatably provided in a required arrangement.

As shown in FIG. 2, the ink ribbon 17 pulled out from the supply-side ribbon winding reel 3 has a first guide roller 50a, a tape roller 31c of the supply-side tension arm 31, a second guide roller 50b, Third guide roller 50c, supply-side pinch roller 41, fourth guide roller 50d, supply-side pressure receiving roller 47, fifth guide roller 50
e, sixth guide roller 50f, winding-side pressure receiving roller 48,
The seventh guide roller 50g, the take-up side pinch roller 42, the eighth guide roller 50h, the ninth guide roller 50i, the tape roller 32c of the take-up side tension arm 32, the tenth guide roller
, And the leading end thereof is wound on the winding ribbon winding reel 4. The supply-side ribbon winding reel 3 and the winding-side ribbon winding reel 4 are applied with torque in the directions of arrows C and D by drive motors 9 and 10 provided for each of the reels 3 and 4, respectively. 17 is provided with a required tension. When the thermal head transfer unit 21 is driven from this state to lower the thermal head 24, the transfer path of the ink ribbon 17 is changed by the pressing force of the thermal head 24 as shown in FIG. And the other part thereof comes into contact with the peel angle adjusting roller 49.

The carriage driving motor 1a, the supply side ribbon winding reel driving motor 9, the winding side ribbon winding reel driving motor 10, the head driving motor 24a and the thermal head 24 are controlled by a control device shown in FIG. You.

As is clear from FIG. 6, the control device 60 of this embodiment comprises a CPU 61, a memory 62, a D / A converter 6
3, a motor driver 64 and a head drive circuit 65. The memory 62 has a work program storage section 66a, a constant storage section 66b, and an applied voltage storage section 66.
c) is provided.
An A / D converter 67 is connected to an input terminal of the control device 60.
a, 67b, 67c, 67d, 67e, the print medium detecting means 2a, the supply-side potentiometer 33, the take-up potentiometer 34, the supply-side load cell 45, and the take-up load cell 46 are connected, and the counter 68a,
The supply-side rotary encoder 15 and the winding-side rotary encoder 16 are connected via 68b. On the other hand, at the output end of the control device 60, via a motor driver 69, a carriage driving motor 1a, a driving motor 9 for the supply-side ribbon winding reel 3, a driving motor 10 for the winding-side ribbon winding reel 4, and a head. The drive motor 24a is connected, and the thermal head 24 is connected via the head drive circuit 70.

The work program storage section 66a of the memory 62
The procedure for tension calibration performed before starting printing on the print medium P (FIG. 7) and the procedure for tension adjustment performed during printing on the print medium P (FIG. 8)
Are stored, and the CPU 61 controls the motors 1a, 9, 10, 24a and the thermal head 24 in accordance with these work procedures.

The operation of the thermal printer according to this embodiment will be described below with reference to FIGS.

When the print medium P is set on the platen 2, the control device 60 switches to the tension calibration mode shown in FIG.
The head drive motor 24a is started by a command from U61, and the thermal head 24a moves from the standby position to the printing position.
Is started (step S1).

The CPU 61 calculates the descending distance of the thermal head 24 from the rotation angle of the head drive motor 24a (the number of steps when a stepping motor is used), and stores the thermal head 24 in a constant storage section 66b of the memory 62 in advance. It is repeatedly determined whether or not the contact position A with the ink ribbon 17 has been reached (step S2). When it is determined that the thermal head 24 has reached the contact position A, the supply-side ribbon winding reel drive motor 9 is started,
The feeding of the ink ribbon 17 from the supply-side ribbon winding reel 3 is started (step S3). At this time, the rotation speed of the supply-side ribbon winding reel drive motor 9 is set to a low speed, for example, 30 rpm. The rotation speed of the supply-side ribbon winding reel drive motor 9 is determined by reading a required motor drive voltage according to a rotation speed command from the CPU 61 from the applied voltage storage unit 66c of the memory 62, and converting the motor drive voltage into a D / A. The voltage is converted into a voltage value which is analog data by the converter 63, and the voltage is controlled by driving the motor driver 64 with this voltage value.

Next, the CPU 61 sets the thermal head 2
4 is repeatedly determined whether or not the print position B has reached the print position B stored in advance in the constant storage unit 66b of the memory 62 (procedure S
4) When it is determined that the thermal head 24 has reached the printing position B, the driving of the head drive motor 24a is stopped (step S5). Further, the CPU 61 controls the supply-side potentiometer 3 provided on the supply-side tension arm 31.
3 and the output of the supply side load cell 45 are detected, and the swing position of the supply side tension arm 31 is stored in the memory 62 in advance.
It repeats whether or not the output has returned to the predetermined position R stored in the constant storage unit 66b, and whether or not the output of the supply-side load cell 45 has returned to the predetermined value L previously stored in the constant storage unit 66b of the memory 62. It is determined (step S6), and the swing position of the supply-side tension arm 31 returns to the predetermined position R,
When it is determined that the output of the supply side load cell 45 has returned to the predetermined value L, the supply side ribbon winding reel drive motor 9 is stopped (step S7).

The CPU 61 calculates the cumulative rotation angle S from the output of the supply-side rotary encoder 15 provided on the supply-side ribbon winding reel 3 from the start to the stop of the supply-side ribbon winding reel drive motor 9. (Step S8) This is stored in the memory 62 (Step S9), and the tension calibration mode is ended. After the completion of the tension calibration mode, the thermal printer 24 returns to the standby position.

When the above operation procedure is completed, the control device 6
0 switches to the print mode of FIG. And CPU6
The head drive motor 24a is activated by a command from the controller 1, and the lowering of the thermal head 24 from the standby position to the printing position is started (step S11).

The CPU 61 calculates the descending distance of the thermal head 24 from the rotation angle of the head drive motor 24a (the number of steps when a stepping motor is used), and stores the thermal head 24 in the constant storage section 66b of the memory 62 in advance. It is repeatedly determined whether or not the contact position A with the ink ribbon 17 has been reached (step S12), and when it is determined that the thermal head 24 has reached the contact position A, the drive motor 9 is started and supplied. The feeding of the ink ribbon 17 from the side ribbon winding reel 3 is started (step S1).
3). At this time, the rotation speed of the drive motor 9 is set to a high speed, for example, 150 rpm.

Next, the CPU 61 calculates the rotation angle of the supply-side ribbon winding reel 3 by counting the output of the supply-side rotary encoder 15 provided on the supply-side ribbon winding reel 3, and determines the rotation angle in step S9. It is repeatedly determined whether or not the accumulated rotation angle S stored in the memory 62 has been reached (step S14). When it is determined that the rotation angle of the supply-side ribbon winding reel 3 has reached the cumulative rotation angle S, the drive of the drive motor 9 is stopped (step S1).
5).

Next, the CPU 61 sets the thermal head 2
4 is repeatedly determined as to whether or not the print position B has reached the print position B stored in the constant storage unit 66b of the memory 62 in advance (step S1).
6) When it is determined that the thermal head 24 has reached the printing position B, the driving of the head drive motor 24a is stopped (step S17). Thereafter, the CPU 61 activates the head drive circuit 65 and executes printing on the print medium P (step S18). Hereinafter, each time a new print medium is supplied onto the platen 2, the operation procedure of FIGS. 7 and 8 is repeated.

In the embodiment, in step S6, the output of the supply-side potentiometer 33 provided in the supply-side tension arm 31 and the supply-side load cell 45
Is detected to determine whether the tension acting on the ink ribbon 17 is appropriate. However, it is necessary to detect only one of the output of the supply-side potentiometer 33 and the output of the supply-side load cell 45. By
It is also possible to determine whether or not the tension acting on the ink ribbon 17 is appropriate.

In the above-described embodiment, a printer of the type in which the thermal head 24 does not move up and down during the printing in step S18 has been described as an example. However, the thermal head 24 is repeatedly moved up and down during the printing. The type of printer can be dealt with by repeating the operation procedure of FIG. 7 every time the thermal head 24 is operated down.

[0042]

According to the present invention, before starting printing on a print medium, the supply-side ribbon necessary for moving the thermal head from the standby position to the printing position and holding the tension arm at a predetermined appropriate position is provided. The rotation angle of the winding reel is determined, and during printing, every time the thermal head is moved from the standby position to the printing position, the supply-side ribbon winding reel is moved by the determined rotation angle prior to the movement of the thermal head. Since the ink ribbon is driven to rotate and the ink ribbon is paid out from the reel, the tension of the ink ribbon can always be regulated within a required appropriate range irrespective of the operation of the thermal head, and high quality printing without uneven printing can be obtained. it can. In addition, since the rotation angle of the supply-side ribbon winding reel is calibrated for each print medium, the number of times of calibration work is smaller than the case where the rotation angle of the supply-side ribbon winding reel is calculated every time the thermal head is reciprocated. And printing can be performed efficiently.

Further, in the present invention, since the ultrasonic motor is used as the drive motor for the supply-side and take-up side ribbon winding reels, the supply-side ribbon take-up reel and the take-up side ribbon are reduced in noise and vibration. The uneven rotation of the winding reel can be suppressed.

Further, according to the present invention, as a detecting means for detecting the tension of the ink ribbon, a potentiometer for detecting the swing amount of the tension arm, a load cell for directly detecting the tension acting on the ink ribbon, or both of them. With this arrangement, the tension acting on the ink ribbon can be accurately detected, and high-quality printing without uneven printing can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a thermal printer according to an embodiment.

FIG. 2 is a front view of a main part of the thermal printer according to the embodiment when the thermal head is at a standby position.

FIG. 3 is a front view of the thermal printer according to the embodiment when the thermal head is at a printing position.

FIG. 4 is a plan view of a main part of the thermal printer according to the embodiment.

FIG. 5 is a perspective view of a tension arm according to the embodiment.

FIG. 6 is a configuration diagram of a control device according to the embodiment.

FIG. 7 is a flowchart illustrating an operation of the thermal printer according to the embodiment.

FIG. 8 is a flowchart illustrating an operation of the thermal printer according to the embodiment.

[Explanation of symbols]

 Reference Signs List 1 carriage base 2 platen 3, 4 tape reel 9, 10 tape reel drive motor 15, 16 rotary encoder 17 ink ribbon 24 thermal head 31, 32 tension arm 33, 34 supply-side potentiometer 60 controller

Claims (3)

[Claims] A supply-side ribbon winding reel and a driving motor thereof; a winding-side ribbon winding reel and a driving motor thereof; and a supply-side ribbon winding reel pulled out from the supply-side ribbon winding reel. An ink ribbon wound on a reel, a thermal head and a motor for driving the thermal head arranged reciprocally in a transport path of the ink ribbon, a platen arranged opposite to the thermal head, and transport of the ink ribbon A tension arm that is swingably disposed in the path to apply a required tension to the ink ribbon; a tension detection unit that detects a tension acting on the ink ribbon; and a control that controls the thermal head and the driving motors. Before starting printing on a print medium supplied on the platen, the thermal head The ink ribbon is fed from the supply-side ribbon winding reel while moving from a standby position separated from the platen to a printing position in contact with the platen via the ink ribbon and a print medium, and the tension arm is determined in advance. Then, the rotation angle of the supply-side ribbon winding reel required to maintain the appropriate position is determined.Then, the thermal head is returned to the standby position, and the winding-side ribbon winding reel is rotationally driven. After the tension of the ink ribbon is returned to the initial state, printing on a print medium is started, and from the start of printing on the one print medium to the completion of printing, every time the thermal head is moved from the standby position to the print position. Prior to the lowering of the thermal head, the supply-side lid is rotated by a rotation angle corresponding to the obtained rotation angle. Thermal printer a down winding reel is rotationally driven in the feeding direction of the ink ribbon, characterized in that it held to a proper value the tension acting on the ink ribbon. 2. The thermal printer according to claim 1, further comprising an ultrasonic motor as a drive motor for driving the supply-side ribbon winding reel and the winding-side ribbon winding reel. 3. The apparatus according to claim 1, wherein said tension detecting means includes a potentiometer for detecting a swing amount of said tension arm and / or a load cell for directly detecting a tension acting on said ink ribbon. The described thermal printer.