JPH01150557A - Thermal printer - Google Patents

Abstract

PURPOSE:To reduce the recording density irregularities of a recording medium due to the setting efficiency by controlling a power supply device such that the voltage detected via a remote sensing wire remains constant. CONSTITUTION:A power supply terminal of a power supply device 2A having a remote sensing function for maintaining the output voltage at a load end constant is connected to a thermal head 1 via a thermal head driving power supply line 3, and a remote sensing terminal is also connected to the thermal head 1 via a remote sensing wire 5. The thermal head driving current generated by the power supply device 2A is supplied to the thermal head 1 via a thermal head driving power supply wire 3. The total current NI is allowed to flow through the thermal head driving power supply wire 3 by selecting the number N out of a row of thermal resistance units 4, and the voltage drop of NIXR3 is produced in the wire resistance R3 of the thermal head driving power supply wire 3 by the total current NI. The amount of the voltage drop is caused to change depending on the number N selected, but the supply voltage El can be maintained constant by controlling the output voltage E2 by means of the power supply device 2A having the remote sensing function for maintaining the voltage detected via the remote sensing wire 5 constant.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal printer device, and particularly to a thermal printer device with improved printing quality.

[Prior Art 1] FIG. 3 is a diagram showing a schematic configuration of a conventional thermal printer device. In the figure, (1) is a thermal head, (2
) is a power supply device for driving this thermal head (1), (3) is a power supply line for driving the thermal head that connects the thermal head (1) and the power supply device (2), and (4) is a power supply line for driving the thermal head (1). ) is a row of heat generating resistors.

FIG. 4 is a diagram showing a schematic circuit configuration of FIG. 3.

In the figure, (R3) is the line resistance of the thermal head driving power supply line (3), (R4) is the heating resistance of the heating resistor array (4), (El) is the supply voltage to the thermal head (1), (
R2> is the output voltage of the power supply device (2), and (I) is the current flowing through the heating resistor (R4).

A conventional thermal printer device is configured as described above.
The thermal head driving current generated by the power supply device (2) is supplied to the thermal head (1) through the thermal head driving power supply line (3).

A control circuit (not shown) selects each heat generating resistor (R4) of one heat generating resistor row (4) and causes a current (I) to flow therethrough. The thermal head drive power supply line (
The total current flowing through 3) is NI. Each heating resistor selectively generates heat according to the selected pattern and prints on a recording medium.

[Problem to be solved by the invention] In conventional thermal printer equipment like the one mentioned above.

The total current (N I ) changes depending on the number of heating resistors selected (N), and since the total current (N I ) flows through the thermal head drive power supply line (3), a voltage drop occurs due to the wire resistance (R3). , the supply voltage (El) is E1=E2-(R3+R
3) XNI, which varies depending on the supply voltage (El) or the number of heat generating resistors selected (N). When the supply voltage (El) changes, the amount of heat generated by each heating resistor in the heating resistor array (4) changes. In other words, the number of selections (N) in one heating resistor row (4),
That is, there is a problem in that recording density unevenness occurs on the recording medium depending on the printing rate.

The present invention has been made to solve these problems, and an object of the present invention is to provide a thermal printer device in which unevenness in recording density of a recording medium due to printing rate is reduced.

[Means for Solving the Problems] A thermal printer device according to the present invention includes a thermal head consisting of nine heat-generating resistor arrays, and a drive current for driving the thermal head, so that the output voltage at the load end is kept constant. a power supply device having a remote sensing function, a plurality of power supply lines connecting each of the heating resistors and the power supply device, and a plurality of remotes having one end connected to the power supply line and the other end connected to the power supply device. It is equipped with a sense line.

[Operation] In the present invention, voltage drop in the supply voltage is prevented by connecting the remote sense line of the power supply device to the power supply terminal of the thermal head.

The power supply device keeps the voltage supplied to the thermal head constant regardless of the total current, and by keeping the supply voltage constant, unevenness in the recording density of the recording medium due to the printing rate is reduced.

[Embodiment] FIG. 1 is a diagram showing a schematic configuration of a thermal printer device according to an embodiment of the present invention. In the figure, (1), (
3) and (4) are similar to the conventional latch shown in FIG.

(2A) is a power supply device having a remote sense function to keep the output voltage at the load end constant, and its power supply terminal is connected to the thermal head (1) via the thermal head drive power line (3), and A remote sense terminal is connected to the thermal head (1) via a remote sense line (5).

FIG. 2 is a diagram showing a schematic circuit configuration of FIG. 1.

In the figure, since only a new remote sense line (5) is connected to that in FIG. 4, explanation of the reference numerals will be omitted.

In the thermal printer device configured as described above, the thermal head driving current generated by the power supply device (2A) is supplied to the thermal head (1) through the thermal head driving power supply line (3). The remote sense line (5) of the power supply device ff (2A) is connected to this supply point.

A total current (NI) flows through the thermal head driving power supply line (3) depending on the selected number (N) in the heating resistor array (4). This total current (NI) is used to generate the power supply line for driving the thermal head (
3) A voltage drop (NIXR3) occurs in the line resistance (R3). The amount of voltage drop mentioned above changes depending on the number of selections (N), but the output voltage (R2) is controlled by the power supply unit ff1 (2A), which has a remote sense function that keeps the voltage detected by the remote sense line (5) constant. Keep the supply voltage (EI) constant.

In the above embodiment, the thermal head and the power supply device are directly connected by the power supply line for driving the thermal head, but a printed wiring board for relay may be provided. Further, the remote sense line may be connected on the printed circuit board.

[Effects of the Invention] As explained above, the present invention includes a thermal head consisting of one row of heating resistors, and a remote sensing function that supplies a drive current to drive the thermal head and keeps the output voltage at the load end constant. a plurality of power supply lines connecting each of the heating resistors and the power supply apparatus; and a plurality of remote sense lines having one end connected to the power supply line and the other end connected to the power supply apparatus, Since the change in the supply voltage depending on the printing rate is reduced, the amount of heat generated by each heating resistor is constant regardless of the printing rate, and there is an effect that the recording medium has less uneven recording density.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of a thermal printer device according to an embodiment of the present invention, FIG. 2 is a schematic circuit diagram of FIG. 1, FIG. 3 is a schematic configuration diagram of a conventional thermal printer device, and FIG.
The figure is a schematic circuit diagram of FIG. 3. In the figure, (1)... thermal head, (2A)...
...Power supply equipment] (3) ...Power supply line for driving the thermal head, (4) ...Heating resistor array, (5) ...Remote sense line. In addition, the same reference numerals in each figure represent the same or corresponding parts.
So Ga Do Teru ■-j Ng 1 diagram
4 W-) Figure 2

Claims (1)

[Claims] A thermal head consisting of a row of heat generating resistors, a power supply device having a remote sensing function that supplies a drive current for driving the thermal head and keeps an output voltage at a load end constant, each of the heat generating resistors and the power source. A plurality of power supply lines are provided to connect the device to the device, and a plurality of remote sense lines are connected at one end to the power supply line and at the other end to the power supply device, and to keep the voltage detected by the remote sense line constant. A thermal printer device, characterized in that the power supply device is controlled by: