JPH06246952A - Thermal printer - Google Patents

Abstract

PURPOSE:To use electric power efficiently and enable printing to be obtained through proper hysteresis control at all times by generating the frequency of fundamental pulses for controlling a head driving circuit according to changes of printing speed, and adjusting the capacity pulse decomposition. CONSTITUTION:The outer device acts to determine the dividing ratio of a reference pulse in accordance with commands that are received from, e.g. a host computer, or the printing speed that is selected by inputting and switching from the panel face of a printer. In this manner, the pulse width and frequency of fundamental pulses for controlling the head driver are determined, and printing is executed by controlling the head heating. When the printing speed is increased, the driving ratio is raised to increase the decomposition capacity of head heating time. If the printing speed is, e.g. 6 in/sec., and the reference clock is used intactly as fundamental pulses, when the printing speed is 3 in/sec., the repeating frequency of the fundamental pulses is made half (1/2) in use by a divider. In practical use, the most suitable value of more precisely divided ratio is determined experimentally, and then stored in a memory so that this value is used.

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 head heating history control.

[0002]

2. Description of the Related Art In a conventional apparatus, the width of one pulse for printing is uniquely determined by hardware.
The history control is performed by the ratio of the pulse width of the one pulse. Besides, set the setting of 1 pulse to the minimum value,
History control is performed according to the total number of one pulse. In any case, a table for defining the ratio or the total number is set in the program for history control, and the width of the basic pulse is constant.

[0003]

In the conventional pulse control used for history control, since the basic pulse is uniquely determined by hardware, a table of set values is indispensable in the history program, The need to change tables or multiple tables due to changes in print media and print materials,
There was a drawback that the ROM containing the program had to be recreated.

The present invention provides a thermal printer which controls the history pulse without changing the hardware with a pulse whose resolution of the history pulse is improved by performing frequency division of the basic pulse by software.

[0005]

The control of the history pulse of the thermal printer according to the present invention is characterized in that the resolution of the basic pulse of the history control is increased by dividing the basic pulse according to the printing speed. .

[0006]

According to the present invention, the ROM table can be simplified by dividing the basic pulse in accordance with the printing speed and increasing the resolution of the basic pulse for history control.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the basic structure of the present invention. The clock (C0) from the CPU (1) is input to the frequency divider (2), and the clock (C1) is used as a basic pulse for heating control of the thermal head (4) through the driver (3).

For example, 70 mm / sec and 150 mm
In the history of printers that can print at a speed of / sec,
A temperature rank is set according to the value of the thermistor of the thermal head, and a table for setting the number of basic pulses for each temperature rank is written in the ROM. At this time, since the conventional basic pulse number table has, for example, two types of speeds, two types are required, but in the present invention, one basic table may be set, which is 70 mm / sec. 15
For two types of speed of 0 mm / sec, 1: 2,
Based on a printing speed of 150 mm / sec, 7
When the printing speed is 0 mm / sec, the repetition frequency of the basic pulse is halved by the frequency divider. With the method of halving this, there is no need to modify the hardware substrate or polarize the ROM.

FIG. 2 is a diagram showing a concrete configuration example of the device of the present invention, which includes (1), (2), (3). (4) is the CPU, frequency divider, head driver, and thermal head, respectively. The head driver (31) includes a sensitivity sensor (such as a thermistor) for detecting the temperature of the head block. (5) is a fixed memory that stores control programs, data, etc., and is composed of, for example, a ROM, a storage area (51) for various control programs necessary for printing, and a storage area for programs related to head heating history control. (5
2) It has a region (53) in which an applied pulse table corresponding to the temperature of the head block is stored.

(6) is a font memory that stores character fonts and the like. Reference numeral (7) denotes a buffer memory, which is a reception buffer memory area for temporarily storing print information received from an external device, for example, a host computer in a code form, and a receive buffer memory for storing print information expanded and stored in a bit pattern according to the print. It has areas and the like.

FIG. 4 is a diagram showing an example of the configuration of a conventional thermal printer, in which elements common to those in FIGS. 1 and 2 are designated by the same reference numerals. In this case, as described above, the head driver (3) is directly controlled by the clock from the CPU (1). Further, the applied pulse table needs a plurality of tables so as to correspond to the printing speed as well as the head temperature.

Next, the general operation of the device of the present invention will be described.
The dividing ratio of the reference pulse (C0) is determined according to a command received from an external device, for example, a host computer, or input from the panel surface of the printer or a printing speed selected by switching a switch. As a result, the pulse width and frequency of the basic pulse (C1) for controlling the head driver are determined, head heating is controlled, and printing is performed.

As the printing speed increases, the division ratio is increased
Increase the time resolution of head heating. For example, when the printing speed is 6 inches / second, if the reference clock (C0) is used as it is as the basic pulse (C1) (frequency division ratio =
In the case of 1), when the printing speed is 3 inches / second, the internal program divides the reference clock into ⅙, and the pulse width of the basic pulse becomes 6 times the reference clock. When the printing speed is returned to 6 inches / second, the division ratio = 1
Return to.

In an actual case, the optimum value of the frequency division ratio, which is extremely fine, is experimentally determined and stored in the memory.
Use this. On the other hand, when the temperature of the head block fluctuates, the head heating control is performed by the application pulse table at a rate corresponding to this.

[0015]

【The invention's effect】

1) By increasing the resolution of the basic pulse, the basic pulse can be selected according to the speed, and the power efficiency can be improved. 2) Further, in order to increase the resolution, the frequency divider is controlled by software, so that it is possible to save the trouble of replacement by changing the ROM and remodeling by changing the hardware.

3) Regardless of changes in the print medium and the print object, printing can be always performed by appropriate history control.

[Brief description of drawings]

FIG. 1 is a basic configuration diagram of print head control of a thermal printer of the present invention.

FIG. 2 is a diagram of an embodiment of the thermal printer of the present invention.

FIG. 3 is an example of a flow of head heating control in the thermal printer of the present invention.

FIG. 4 shows an example of head heating control in a conventional thermal printer.

[Explanation of symbols]

 1 CPU 2 Frequency divider 3 Thermal head driver 31 Temperature sensor 4 Heating element part 5 Control memory (ROM) 51 Control program 52 Head history control program 53 Head applied pulse table 5A Control memory 6 Character font memory 7 Buffer memory B Data bus line

Claims (2)

[Claims] 1. A thermal printer for heating one dot by a plurality of heating pulses, comprising means for adjusting the pulse resolution by changing the frequency of a basic pulse for controlling a head drive circuit in response to a change in printing speed. This is a thermal printer. 2. A frequency divider is provided between the clock pulse generator and the head drive circuit, and the frequency of the basic pulse is changed by changing the frequency division ratio. Thermal printer.