JP2001205834A - Thermal printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermal printer in which positional shift of a print sheet due to ambient temperature variation is corrected. SOLUTION: A thermistor 7 is provided in the vicinity of platen 2 and the output from the thermistor 7 is inputted to a motor control section 8. The motor control section 8 controls the rotational amount of a stepping motor 5 depending on the input to the thermistor 7 thus correcting positional shaft of a thermal sheet 6.

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 thermal printer for correcting a shift of a printing paper position due to a temperature change.

[0002]

2. Description of the Related Art A conventional thermal printer of this type will be described with reference to the drawings.

FIG. 4 is a schematic structural perspective view showing a conventional thermal printer.

Referring to FIG. 4, a thermal printer 20
Is a thermal head 1 for printing on the thermal paper 6, a platen 2 disposed opposite to the thermal head 1 with the thermal paper 6 interposed therebetween, and conveying the thermal paper 6 by frictional force, and provided on a central axis of the platen 2. The motor includes a stepping motor 5 for transmitting a rotational drive to the platen pulley 3 and the motor pulley 9 via the belt 4 via the belt 4, and a motor control unit 27 for controlling the rotation of the stepping motor 5.

Next, the operation of the thermal printer 20 configured as described above will be described.

When printing on the thermal paper 6, the thermal paper 6
Is a belt 4 that is located between the thermal head 1 and the platen 2 and is hung on the motor pulley 9 and the platen pulley 3.
, The rotational drive of the stepping motor 5 is transmitted to the platen 2 under the control of the motor control unit 27, and is conveyed in the sheet conveying direction shown in FIG. 3 by the frictional force between the thermal paper 6 and the thermal head 1 and the platen 2. However, when the thermal paper 6 is being conveyed, printing is performed on the thermal paper 6 by applying the applied energy to the thermal head 1.

Here, the motor control unit 27 controls the rotation amount of the platen 2 to be constant by setting the rotation drive amount of the stepping motor 5 to a constant step amount regardless of the ambient environment temperature.

Accordingly, when the ambient temperature of the platen 2 is low, the slip amount increases due to the decrease in the frictional force between the platen 2 and the thermal paper 6, and the platen 2 diameter shrinks. 2 and the thermal head 1, the transport amount of the thermal paper 6 that is transported by the frictional force is reduced, causing a transport delay, and the actual printing position of the thermal paper 6 with respect to the predetermined printing position is shifted in the paper transport direction. On the other hand, there arises a problem that it is shifted forward.

On the other hand, when the ambient temperature of the platen 2 is high, the slip amount decreases due to an increase in the frictional force between the platen 2 and the thermal paper 6, and the diameter of the platen 2 expands. As a result, the transport amount of the thermal paper 6 pressed by the platen 2 and the thermal head 1 and transported by the frictional force increases, and the transport advances, and the actual printing position with respect to the predetermined printing position of the thermal paper 6 is There is a problem that it is shifted rearward with respect to the transport direction.

[0010]

As described above,
Conventional thermal printers, regardless of the ambient temperature,
Because the rotation amount of the stepping motor is controlled to be a constant step amount and the rotation amount of the platen is kept constant, the transport amount of the thermal paper changes at high and low temperatures compared to normal temperature. However, there is a problem that an actual printing position is shifted from a predetermined printing position of the thermal paper.

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermal printer which corrects a shift of a printing paper position due to a change in ambient temperature.

[0012]

According to a first aspect of the present invention, there is provided a thermal printer for printing on a print sheet, and a platen disposed to face the thermal head across the print sheet and transporting the print sheet. A motor that drives the platen to rotate, a temperature sensor provided near the platen, and a motor control unit that receives the output of the temperature sensor and controls the rotation of the motor. The amount of rotation of the motor is controlled accordingly.

According to a second aspect of the present invention, there is provided a thermal printer for performing printing on a printing paper, a platen disposed to face the thermal head across the printing paper, and transporting the printing paper, and rotating the platen. A motor to be driven, a temperature sensor provided in the vicinity of the platen, printing paper identification means for identifying a printing paper manufacturer, and a motor control unit which receives the outputs of the temperature sensor and the printing paper identification means and controls the rotation of the motor. And the motor control unit controls the amount of rotation of the motor in accordance with the output from the temperature sensor and the printing paper identification unit.

The motor control section is characterized in that the motor control section performs control to decrease the rotation amount of the motor at a high temperature and increase the rotation amount at a low temperature.

The motor controller increases or decreases the rotation amount at high or low temperatures with respect to the rotation amount of the motor at normal temperature.

The motor is characterized in that it has a motor pulley and transmits the rotational drive of the motor to the platen via a belt to the platen pulley and the motor pulley provided on the center axis of the platen.

The motor is a stepping motor.

The printing paper is transported by a frictional force with a platen and a thermal head.

The temperature sensor is a thermistor.

The printing paper is a heat-sensitive paper.

[0021]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic perspective view showing a first embodiment of a thermal printer 10 according to the present invention, and FIG. 2 is a schematic front view of the configuration.

The same components as those of the conventional thermal printer 20 shown in FIG. 4 are denoted by the same reference numerals.

Referring to FIGS. 1 and 2, a thermal printer 10 includes a thermal head 1 for printing on a thermal paper 6 and a thermal head 6 arranged opposite to the thermal head 1 with the thermal paper 6 interposed therebetween. A platen 2 that conveys by force, a stepping motor 5 that transmits a rotational drive to the platen 2 via a belt 4 to a platen pulley 3 and a motor pulley 9 provided on a center axis of the platen 2, and a platen 2 provided near the platen 2 It comprises a thermistor 7 and a motor controller 8 that receives the output of the thermistor 7 and controls the rotation of the stepping motor 5. The motor controller 8 controls the amount of rotation of the stepping motor 5 according to the output of the thermistor 7. It is configured as follows.

Next, the operation of the thermal printer 10 configured as described above will be described.

When printing on the thermal paper 6, the thermal paper 6
Is a belt 4 that is located between the thermal head 1 and the platen 2 and is hung on the motor pulley 9 and the platen pulley 3.
The rotation of the stepping motor 5 controlled by the motor control unit 8 is transmitted to the platen 2 through the
The paper is transported in the paper transport direction shown in FIG. 3 by the frictional force between the thermal paper 1 and the platen 2.
When is transported, printing is performed on the thermal paper 6 by applying the applied energy to the thermal head 1.

Here, since the thermal printer 10 is generally used in an installation environment temperature range of 0 to 40 degrees Celsius, the motor control unit 8 reduces the rotation amount of the stepping motor 5 at a high temperature. At low temperatures, control is performed to increase the step amount. At high temperatures, the step amount is reduced, at low temperatures, the step amount is increased, and the rotation amount of the platen 2 is increased. By performing the change, control is performed such that the transport amount of the heat-sensitive paper 6 becomes equal at the high temperature and the low temperature as compared with the normal temperature.

When the ambient temperature of the platen 2 is low (0 to 5 degrees Celsius), the slip amount increases due to a decrease in the frictional force between the platen 2 and the thermal paper 6, and the platen 2 increases. Due to the contraction of the two diameters or the like, the transport amount of the thermal paper 6 pressed and transported by the platen 2 and the thermal head 1 decreases, causing a transport delay, and the actual printing position of the thermal paper 6 relative to a predetermined printing position is reduced. Experiments have shown that the printing position is shifted by about 0.2 mm to 0.25 mm forward with respect to the paper transport direction.

Therefore, the motor controller 8 sets the step amount of the stepping motor 5 to two steps (0.12 steps) with respect to the normal temperature based on the input from the temperature detecting thermistor 7.
By increasing the value (in the case of 5 mm / 1 step), it is possible to perform position correction control by correcting the transport amount of the thermal paper 6 and print at a predetermined print position.

When the ambient temperature of the platen 2 is high (35 degrees Celsius to 40 degrees Celsius), contrary to the low temperature,
Due to the decrease in the slip amount due to the increase in the frictional force between the platen 2 and the thermal paper 6 and the expansion of the diameter of the platen 2, the platen 2 is pressed by the thermal head 1 and conveyed by the frictional force. Although the transport amount of the thermal paper 6 increases and the transport advances, the actual printing position is shifted from the predetermined printing position of the thermal paper 6 by about 0.2 mm to 0.25 mm rearward with respect to the paper transport direction. The motor control unit 8 reduces the step amount of the stepping motor 5 by two steps (0.125 mm / 1 step) with respect to the normal temperature, based on the input from the thermistor 7, so that the transport amount of the thermal paper 6 is , The position can be controlled at the predetermined print position.

The deviation of the thermal paper 6 from the ambient temperature is determined in advance by an experiment, and the optimal amount of the stepping motor 5 is determined as a correction amount. The position correction control of the thermal paper 6 is performed. In the above embodiment, the temperature correction is controlled only at the time of high temperature and low temperature. However, the temperature correction is controlled by subdividing the temperature range. It is obvious that this also has the same effect, and it goes without saying that it is included in the present invention.

As described above, the thermistor 7 is provided near the platen 2, the output of the thermistor 7 is input to the motor control unit 8, and the motor control unit 8 controls the stepping motor according to the output of the thermistor 7 corresponding to the ambient temperature. By controlling the amount of rotation of 5, the position shift of the thermal paper 6 due to a change in ambient temperature can be corrected, and there is an effect that printing can be performed at a predetermined print position.

Next, a second embodiment of the thermal printer of the present invention will be described with reference to the drawings.

FIG. 3 is a schematic structural perspective view showing the thermal printer 16 of the present invention.

The same components as those of the thermal printer 10 according to the first embodiment are denoted by the same reference numerals.

Referring to FIG. 3, the thermal printer 16
Is a thermal head 1 for printing on the thermal paper 6, a platen 2 disposed opposite to the thermal head 1 with the thermal paper 6 interposed therebetween, and conveying the thermal paper 6 by frictional force, and provided on a central axis of the platen 2. A stepping motor 5 for transmitting rotational drive to the platen 2 via the belt 4 to the platen pulley 3 and the motor pulley 9, a thermistor 7 provided near the platen 2, and thermal paper identification for identifying the manufacturer of the thermal paper 6. Means 11 and a motor control unit 12 which receives the outputs of the thermistor 7 and the thermal paper identification means 11 and controls the rotation of the stepping motor 5. The motor control unit 12 comprises the thermistor 7 and the thermal paper identification means 1.
1 is configured to control the amount of rotation of the stepping motor 5 in accordance with the output from the control unit 1.

Next, the operation of the thermal printer 16 configured as described above will be described.

The difference from the first embodiment is that a thermal paper identification means 11 is provided, and in addition to the ambient temperature, the thermal paper 6
Only the operation of controlling the amount of rotation of the stepping motor 5 in correspondence with the manufacturer described above will be described below, focusing on differences from the first embodiment.

The amount of deviation of the transport amount of the thermal paper 6 from various manufacturers with respect to the ambient temperature as compared with the normal temperature is determined in advance by an experiment, and the step amount of the stepping motor 5 that is optimal for the thermal paper 6 of each manufacturer Is determined in advance, and at the time of printing, the position of the thermal paper 6 is determined by the motor control unit 12 according to the temperature from the thermistor 7 and the manufacturer of the thermal paper 6 from the thermal paper identification means 11. By performing the correction control, printing can be performed at a predetermined printing position.

Therefore, in addition to the ambient temperature, it is possible to correct the deviation of the transport amount due to the difference in the characteristics such as the friction coefficient of the thermal paper 6 due to the difference in the manufacturer of the thermal paper 6. There is an effect that variations in the printing position due to differences in the manufacturers can be eliminated.

[0041]

As described above, the thermal printer of the present invention has a thermistor for detecting the ambient temperature near the platen, and controls the rotation amount of the stepping motor in accordance with the ambient temperature to correct the position of the thermal paper. Has the effect that printing can always be performed at a predetermined printing position regardless of the ambient temperature.

Further, by providing a thermistor and a thermal paper discriminating means, and controlling the rotation amount of the stepping motor according to the thermal paper manufacturer in addition to the ambient temperature,
This has the effect of eliminating variations in printing position due to differences in thermal paper manufacturers.

[Brief description of the drawings]

FIG. 1 is a schematic configuration perspective view showing a first embodiment of a thermal printer of the present invention.

FIG. 2 is a schematic configuration front view showing a first embodiment of the thermal printer of the present invention.

FIG. 3 is a schematic configuration perspective view showing a second embodiment of the thermal printer of the present invention.

FIG. 4 is a schematic configuration perspective view showing a conventional thermal printer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal head 2 Platen 3 Platen pulley 4 Belt 5 Stepping motor 6 Thermal paper 7 Thermistor 8, 12 Motor control part 9 Motor pulley 11 Thermal paper identification means 10, 16 Thermal printer 20 Thermal printer 27 Motor control part

Claims (9)

[Claims] A thermal head for performing printing on a printing paper, a platen disposed to face the thermal head across the printing paper and transporting the printing paper, a motor for rotating the platen, and the platen A temperature sensor provided in the vicinity, and a motor control unit that receives an output of the temperature sensor and controls rotation of the motor;
The thermal printer according to claim 1, wherein the motor control unit controls a rotation amount of the motor according to an output of the temperature sensor. 2. A thermal head for performing printing on printing paper, a platen disposed to face the thermal head with the printing paper interposed therebetween, and conveying the printing paper, a motor for driving the platen to rotate, and the platen A temperature sensor provided in the vicinity, a printing paper identification unit for identifying a manufacturer of the printing paper, and a motor control unit that receives an output of the temperature sensor and the printing paper identification unit and controls rotation of the motor. And a motor control unit for controlling a rotation amount of the motor according to an output from the temperature sensor and the printing paper identification unit. 3. The thermal printer according to claim 1, wherein the motor control unit performs control to reduce the rotation amount of the motor at a high temperature and increase the rotation amount at a low temperature. 4. The motor control unit according to claim 1, wherein the motor control unit increases or decreases the rotation amount at a high or low temperature with respect to the rotation amount of the motor at a normal temperature. Thermal printer. 5. The motor according to claim 1, wherein the motor has a motor pulley and transmits a rotational drive of the motor to the platen via a belt to a platen pulley provided on a center axis of the platen and the motor pulley. The thermal printer according to claim 1. 6. The thermal printer according to claim 1, wherein the motor is a stepping motor. 7. The thermal printer according to claim 1, wherein the printing paper is conveyed by a frictional force between the platen and the thermal head. 8. The thermal printer according to claim 1, wherein the temperature sensor is a thermistor. 9. The thermal printer according to claim 1, wherein the printing paper is a thermal paper.