JPH09277580A - Thermal head equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means for heating uniformly a heating element. SOLUTION: When control signals 61, 68 which control heating elements 21, 28 at upper and lower ends of a head 2 are not sent out from a control means, second transistors 41B, 48B are controlled by preheat signals 71, 78, and a weak current is introduced to the heating elements 21, 28 at the upper and lower ends of the head 2 to carry out remaining heat. In order to keep temperature of the heating elements 21, 28 at not more than melting temperature of ink, a current is controlled with resistors 41A, 41B, and remaining heat is added to the heating elements 21, 28 by limiting the heating quantity. Thereby, differences in heat accumulation to the heating elements 22, 23, to 27 of a central part of the head 2 are compensated to reduce an irregularity in printing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal head device, and more particularly to a thermal head device having means for uniformly heating heating elements.

[0002]

2. Description of the Related Art As shown in FIG. 2, a conventional thermal head device has a plurality of heating elements 21, 22 arranged in a line.
The head 2 incorporating ~ 28 is pressed against the paper through the ink ribbon, and the head 2 is moved to the right or left direction, and at the same time, the heating elements 21, 22 to 28 are energized to generate heat, thereby causing the heat on the ink ribbon. By controlling the timing at which the ink is melted and the ink is transferred to the paper and the heating elements 21, 22 to 28 are started or stopped, heat is generated in order to print an arbitrary image or character on the paper. It is necessary to determine the energization timing in consideration of the heat storage characteristics of the elements 21, 22, and 28.

[0003]

However, in the case of a head having a plurality of heating elements, a difference occurs in the heat storage characteristics of the individual heating elements, and among the heating elements arranged in a line, the heating elements at both ends are adjacent to each other. Since there is only one heat generating element on one side, it has a characteristic that it is hard to store heat as compared with the heat generating element in the central portion, and unevenness appears in the printing result due to the difference in heat storage characteristics between the central portion of the head and both ends of the head.

Therefore, an object of the present invention is to provide a thermal head device provided with means for uniformly heating the heating elements.

[0005]

In order to solve the above-mentioned problems, the thermal head device of the present invention has a head in which a plurality of heating elements are arranged in the vertical direction, and a plurality of heating elements arranged in the head are driven. A power supply for supplying electric power, a control means for receiving and sending an input control signal for printing, and sending a preheat signal only to the heating elements at the upper and lower ends of the head when the control signal is not received, and From the heat transfer temperature of the head driver, a plurality of head drivers that respectively transfer the driving power to the heating element by the control signal sent from the control means to perform thermal transfer, and by the preheat signal sent from the control means. It is characterized in that it is composed of an upper end and a lower end preheat driver which respectively send the driving power having a low temperature to residual heat.

In order to solve the above-mentioned problems, in the thermal head device of the present invention, a plurality of first transistors having the control signal as a bias are provided between the plurality of heating elements and the power supply. Head driver, and a series circuit of a second transistor and a resistor biased by the preheat signal is composed of the heating elements at the upper and lower ends of the head and the upper and lower preheat drivers provided between the power source, respectively. It is characterized by being done.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a thermal head device according to an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a thermal head device according to an embodiment of the present invention.

As shown in FIG. 1, the thermal head device of the present invention comprises a head 2 having a plurality of heating elements 21, 22, to 28 arranged in a vertical direction, a plurality of heating elements 21 arranged on the head 2. 22 to 28, a power supply 1 for supplying drive power, and control signals 61, 62 for performing the input printing.
~ 68 is received and sent out, and these control signals 61, 62, ~
By the control means 5 for sending the preheat signals 71, 78 only to the heating elements 21, 28 at the upper and lower ends of the head 2 when 68 is not received, and the control signals 61, 62, ... 68 sent from this control means 5, Heating elements 21, 22,
28 to 28, a plurality of head drivers that respectively send driving power to perform thermal transfer, and preheat signals 71 and 78 that are sent from the control means 5 respectively send driving power at a temperature lower than the thermal transfer temperature of the head driver to send residual heat. Upper and lower preheat drivers 41 and 48.

Further, in the plurality of head-drivers, the first transistors 31, 32, -38 biased by the control signals 61, 62, -68 have the plurality of heating elements 21, 22, -38.
28 and the power source 1 respectively, and the upper and lower end preheat drivers 41, 48 are provided with preheat signals 71, 78.
A series circuit of the second transistors 41B and 48B and the resistors 41A and 48A, which are biased by, is provided between the heating elements 21 and 28 at the upper and lower ends of the head 2 and the power supply 1, respectively.

Next, the operation of the thermal head device according to the embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the operation of the thermal head device according to one embodiment of the present invention is sent out from the control means 5 when the control signals 61, 62, to 68 are input to the control means 5. The control signals 61, 62, to 68 are used as biases, and the first transistors 31, 32 to 38 supply the driving power of the power source 1 to the heating elements 21, 22 to 28 to perform thermal transfer. Signals 61, 62, ~ 6
When 8 is not input, the second transistors 41B and 48B use the preheat signals 71 and 78 sent from the control means 5 as biases and supply power to the heating elements 21 and 28 at the upper and lower ends of the head 2 through the resistors 41A and 48A. 1 drive power is supplied to perform residual heat.

Therefore, the heating elements 21 and 28 at the upper and lower ends of the head 2 are heated by supplying a weak current to the residual heat, and the temperatures of the heating elements 21 and 28 at the upper and lower ends of the head 2 at this time are melted by the ink. In order to keep the temperature below
The current is limited by A and 48A to suppress the amount of heat generation.

[0014]

As described above, according to the thermal head device of the present invention, the heating element at the head end portion is preheated to compensate for the difference in the heat storage characteristic with the heating element at the central portion of the head. Has the effect of reducing.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a thermal head device according to an embodiment of the present invention.

FIG. 2 is a block diagram of a conventional thermal head device.

[Explanation of symbols]

1 power source 2 head 5 control means 21, 22, ~ 28 heating element 31, 32, ~ 38 head driver (first transistor) 41, 48 preheat driver 61, 62, ~ 68 control signal 71, 78 preheat signal 41A, 48A resistance 41B, 48B second transistor

Claims (2)

[Claims] 1. A head in which a plurality of heating elements are arranged in a vertical direction, a power supply for supplying driving power to the plurality of heating elements arranged in the head, and a control signal for performing input printing are received and transmitted. , Control means for sending the preheat signal only to the heating elements at the upper and lower ends of the head when this control signal is not received, and the driving power to each of the heating elements by the control signal sent from this control means. A plurality of head drivers for thermal transfer, and the upper and lower end preheat drivers that respectively send the drive power that becomes a temperature lower than the thermal transfer temperature of the head driver by the preheat signal sent from the control means to residual heat. A thermal head device characterized by being configured. 2. A plurality of head drivers, each of which is provided with a first transistor biased by the control signal between the heating elements and the power supply, and a second transistor and a resistor biased by the preheat signal. 2. The thermal head device according to claim 1, wherein the series circuit is composed of heating elements at the upper and lower ends of the head and the upper and lower preheat drivers provided between the power sources, respectively.