JPH06171179A - Thermal transfer ribbon, and thermal head driving method - Google Patents

Abstract

PURPOSE:To miniaturize the structure and to reduce costs while improving reliability. CONSTITUTION:A one-way clutch and a reversible motor 1 are provided, and conveyance of a ribbon is made by normal operation of the motor 1 and by operation of the one-way clutch for ribbon conveyance, and vertical movement of a thermal head 15 is made by reverse operation of the motor 1 and by operation of the one-way clutch for thermal head driving. The motor 1 is controlled, based on outputs for on/off from head position sensors, and thereby the thermal head 15 is stopped in positions respectively for printing and retraction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a one-way clutch, and a single motor capable of forward and reverse rotation is rotated in the forward and reverse directions to selectively drive the thermal transfer ribbon and the thermal head. Ribbon and thermal head driving method.

[0002]

2. Description of the Related Art In a conventional thermal printer, ribbon conveyance and thermal head drive are performed by dedicated motors.

[0003]

Therefore, in the conventional driving method, there is a drawback that the volume of the mechanism portion becomes large and the cost becomes high due to the plurality of motors and the driving circuits of the respective motors. In addition, it takes a lot of time to rotate the harness and the assembling workability is poor. Furthermore, since a plurality of motors are provided, there is a problem in reliability.

The present invention solves the above-mentioned drawbacks of the conventional apparatus,
It is an object of the present invention to provide a thermal transfer ribbon and a method of driving a thermal head, which can achieve size reduction, cost reduction, and reliability improvement.

[0005]

In order to achieve this object, the present invention utilizes a one-way clutch and a single motor capable of forward and reverse rotation is rotated in the forward and reverse directions to thereby provide a thermal transfer ribbon and a thermal transfer ribbon. In a method of driving a thermal transfer ribbon and a thermal head, which are configured to drive the head in a switching manner, the motor is rotated forward when the ribbon is conveyed,
When the ribbon conveyance is stopped, the motor is stopped, while when the thermal head is moved up and down, the motor is rotated in the reverse direction, and several steps from the time when the operating member that rotates in synchronization with the motor turns the detector on (or off). After that, the rotation of the motor is stopped, the thermal head is held at the retract position, and the motor is further rotated in the reverse direction.
The motor is held at the printing position after several steps from the time when the actuating member turns the detector on (or off).

[0006]

In the present invention, when the motor rotates forward, the ribbon is conveyed by the action of the one-way clutch for ribbon conveyance.
On the other hand, when the motor rotates in the reverse direction, the thermal head is moved toward or away from the platen by the action of the one-way clutch for driving the thermal head. Further, the motor is controlled based on the ON / OFF output of the head position detector to stop the thermal head at the print position and the retract position.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a front view showing a drive mechanism of a ribbon supply unit and a thermal head moving unit of a thermal printer according to an embodiment,
FIG. 2 is a side view of the same.

In the figure, 1 is a ribbon winding direction A.
A step motor (hereinafter, simply referred to as a motor) capable of rotating in a normal direction (for example, this is forward rotation) and a head retract (upward) direction B (for example, this is reverse rotation) (see FIG. 1), Reference numeral 2 denotes a first drive pulley (see FIG. 2) to which the driving force of the motor 1 is transmitted by a first endless belt (loop-shaped transmission means) 3. Reference numeral 4 denotes a first drive belt driven by a second endless belt 5. It is a second drive pulley (see FIG. 2) to which the drive force of the pulley 2 is transmitted.

The first drive pulley 2 is attached to a first drive shaft (winding shaft) 6 via a first one-way clutch 7 (see FIG. 2), while the second drive pulley 2 is attached. Four
Is attached to the second drive shaft 8 (head retract camshaft) via a second one-way clutch 9 (see FIG. 2). The first one-way clutch 7 is
When the motor 1 rotates forward, the first drive pulley 2 moves to the first
The second one-way clutch 9 drives the second drive pulley 4 to drive the second drive shaft 8 when the motor 1 reversely rotates. It is provided to be connected.

A winding-side hub 10 for winding a ribbon is attached to the tip of the first drive shaft 6, and
The thermal head assembly 1 is provided at two positions on the second drive shaft 8.
Eccentric cams 13, 13 are provided to abut on the pair of bearings 12, 12 provided on the upper part of the unit 1 from below. The second drive shaft 8 has elongated holes 14 at both ends of the thermal head assembly 11,
14 is provided so as to penetrate through the thermal head assembly 11
Is moved up and down under the action of the eccentric cam 13 by the long holes 14, 14.

Reference numeral 15 is a thermal head, 16 is a platen, 17 is a print frame, 18 is a ribbon cassette, and 1 is a ribbon cassette.
9 is the winding side hub, 20 is its support shaft (see FIG. 1),
Reference numeral 21 is a tension roller (see FIG. 1) that applies tension to the second endless belt 5. The first and second endless belts 3 and 5 may be replaced with a chain that meshes with a sprocket.

In such a structure, when the motor 1 rotates in the normal direction, the driving force transmitted to the first driving pulley 2 is
It is transmitted to the first drive shaft 6 via the first one-way clutch 7 and further transmitted to the winding-side hub 10. Therefore, the ribbon (not shown) is wound up and unwound from the core supported by the side hub 19, and is wound around the core supported by the winding side hub 10. At this time, the second one-way clutch 9 is free in the rotation direction of the second drive pulley 4, and the driving force is not transmitted to the second drive shaft 8.

Next, when the motor 1 rotates in the reverse direction, the rotation direction of the second drive pulley 4 is reversed, and this drive force is transmitted to the second drive shaft 8 via the second one-way clutch 9. . Here, when the second drive shaft 8 rotates, the eccentric cam 13 provided integrally therewith also rotates, and the eccentric cam 1
The thermal head assembly 11 is moved up and down through the bearing 12 that is in contact with the head 3. Therefore, the thermal head 15 can be retracted with respect to the platen 16 as needed. At this time, the first one-way clutch 7
Is free in the rotation direction of the first drive pulley 2, and the driving force is not transmitted to the first drive shaft 6.

Next, the timing of ribbon conveyance and thermal head vertical movement will be described. First, when carrying a ribbon,
The motor 1 is rotated at a constant speed after being started and accelerated in the normal rotation, and the ribbon is conveyed at a constant speed by the winding side hub 10 at the time of the constant speed rotation. When the ribbon conveyance is stopped, the motor 1 is decelerated and stopped.

Next, driving of the thermal head will be described. FIG. 3 is a schematic diagram showing the relationship between each position when the thermal head moves up and down, each position of the light shield plate of the position detector, and the timing operation of the motor. The light shield plate 22 and the transmission type light shown in FIG. The ascending position (retract position) and descending position (printing position) of the thermal head 15 are determined based on whether the position detector including the sensor 23 is turned on or off.

In FIG. 3, the motor 1 is rotated in the B direction, and the time when the light sensor 23 is switched from bright to dark is defined as 0 step, and with this as a reference, the motor 1 is driven for 9 steps and the motor 1 is stopped. This position is the ascending position (retract position) and the home position position. On the other hand, to move it to the lowered position, it is further driven in the B direction. The sensor changes from dark to bright around 74 steps between steps 9 and 259. The motor 1 is stopped when 185 steps are driven and 259 steps are driven due to the change from dark to bright. This position is the lowered position (printing position), and the optical sensor 23 remains bright. To move to the elevated position from here, the actuator is driven in the B direction for a predetermined number of steps, and after 0 steps, is driven for 9 steps to stop and then returns to the original position.

As described above, according to the present invention,
Ribbon transport and vertical movement of the thermal head can be performed with one motor, so the size of the mechanism is reduced and the cost is reduced.
It is possible to improve assembling workability and reliability.

[Brief description of drawings]

FIG. 1 is a front view showing a drive mechanism of a ribbon supply unit and a thermal head moving unit of a thermal printer according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of the drive mechanism.

FIG. 3 is a schematic diagram showing an example of control of vertical movement of a thermal head, the position of the thermal head, and the operation of a position detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Motor 7 1st one-way clutch 9 2nd one-way clutch 10 Winding side hub 11 Thermal head assembly 15 Thermal head 22 Light-shielding plate (operating member) 23 Optical sensor (detector)

Continuation of the front page (51) Int.Cl. ⁵ Identification number Reference number within the agency FI Technical display location B41J 23/02 A 33/38 9012-2C 9305-2C B41J 3/20 117 A

Claims (1)

[Claims] 1. A thermal transfer ribbon and a thermal head, wherein a thermal transfer ribbon and a thermal head are selectively driven by using a one-way clutch and by rotating a single motor capable of normal and reverse rotation in the forward and reverse directions. In the driving method of (1), the motor is rotated forward when the ribbon is conveyed,
When the ribbon conveyance is stopped, the motor is stopped. On the other hand, when the thermal head is moved up and down, the motor is rotated in the reverse direction, and an operating member that rotates in synchronization with the motor turns the detector on (or off) at a predetermined time. After the step, the rotation of the motor is stopped, the thermal head is held at the retract position, the motor is further rotated in the reverse direction, and the operation member turns off (or turns on) the detector. A thermal transfer ribbon and a method of driving a thermal head, characterized in that the thermal head is held at a printing position.