JPS63185656A - Printing controller for thermal printer - Google Patents

Abstract

PURPOSE:To contrive a higher printing speed, by varying an oscillation frequency according to the temperature of a thermal head or the ambient temperature, storing the driving history of a heat generating element covering the preceding two driving operations, and determining an energization period reduced according to a basic total energization time and the driving history. CONSTITUTION:An output signal from a pulse generating circuit 18 having an oscillation frequency according to an output from a heat-sensitive element for detecting the temperature of a thermal head or the ambient temperature is inputted through an energizing pulse input terminal 9, and the pulse thus inputted is converted into an energization period signal by a gate circuit 34. Numeral 31 denotes a latch circuit group for holding a one-dot-column amount of the current head data, and numerals 32, 33 denote latch circuit groups for holding one-dot-column amounts of the past data of the preceding driving operation and the past data of the driving operation before the preceding operation, respectively. When a predetermined pulse is inputted to input terminals 9 after data is set, signals H0, H23 to both end heat generating elements and signals output signals H1-H22 are produced by gate circuits G0, G1 in 35, 36 for producing signals for controlling the heating value according to the driving histories through combining the latched data with the energization period signal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a thermal printer, and particularly relates to a method of driving a heat generating element thereof.

[Conventional technology]

Conventionally, various methods have been used in thermal printers to prevent deterioration in print quality due to heat accumulation during continuous use of thermal printers. Among them, there is a method of determining the energization time by storing the previous data for each dot, as in the case of Special Publication No. 55-48031;
A method such as No. 507 in which the energization time is changed depending on the driving cycle is used. These are generally called history control methods.

[Problem that the invention seeks to solve]

In these conventional examples, a method was generally adopted in which the data was sequentially sent to the drive 1c of the thermal head while the data was processed by the CI'U.

In such a system, even if an attempt is made to operate the thermal printer at high speed, the processing cannot keep up, which has been an obstacle to increasing the speed of the thermal printer.

One object of the present invention is to eliminate such conventional problems,
An object of the present invention is to provide a printing control device for a serial type thermal printer that is high-speed and has excellent printing quality.

[Means for solving problems]

A printing +lr+ control device for a thermal printer according to the present invention includes: a heat-sensitive element that detects the temperature of the thermal head or its surrounding temperature; an oscillation circuit that includes the heat-sensitive element and whose oscillation frequency changes according to the temperature; storage means for storing the drive history of each heat generating element of the thermal head at least twice in the past; the total energization time that is the basis of the heat generating element and the energization period that is reduced according to the drive history; This is print control k'It of a thermal printer characterized by being determined by an oscillation circuit.

〔Example〕

FIG. 1 is a schematic diagram showing the Hi configuration of a print control device for a thermal printer according to the present invention.

Reference numeral 1 denotes a thermal head including a plurality of heat generating elements 1a, 2 a head drive circuit for driving this thermal head, and 3 a head heat generation control circuit unit inserted between the CPU 4 and the thermal head 1 to control the amount of heat generated to the thermal head. , the CPU 4 also generally controls the entire thermal printer. Reference numeral 18 denotes a pulse generation circuit that supplies pulses having two or more types of pulse widths to the head heat generation control circuit unit 3, and a thermistor 14, which is a type of thermal element that detects the temperature of the thermal head l or its surrounding temperature.
is nurturing.

The CPU 4 is, for example, an 8-bit CPU and has a data bus 16, an address bus 17, a WR signal, and the like.

The head heat generation control circuit unit 3 is composed of, for example, a gate array, and is integrated into a single chip like the CPU 4. Hereinafter, the head heat generation control circuit unit will be abbreviated as I-ICU.

The HCU 3 has a built-in data latch circuit, which is a type of storage means, and has a data input terminal 5 connected to the data bus 16.
The address input terminal 8 inputs the lower two bits of the address bus 17, and according to predetermined address information from the CPU 4,
A chip select terminal (C terminal) 7, which is a type of unit select terminal that knows the designation of the unit, a data latch timing input terminal that is input to the CPU 4 signal, and multiple energization pulse inputs that determine the energization time to the heat generating element. It has at least a head drive output terminal lO that outputs a drive signal to each heat generating element of the thermal head l.

11 is II CU from the address information of CI' U 4
This is a decoder that creates a predetermined address code assigned to 3.

12 is a ROM that stores the control program, character generator, etc. of CI' U 4, 13 is a RAM 15
indicates the power supply.

FIG. 2 is a detailed circuit diagram showing one embodiment of II CU 3, and the same parts as in FIG. 1 are designated by the same numbers.

The data input terminal 5 can input 8-bit data D0 to D7 in parallel.

21 to 29 indicate data latch circuits that store 8-bit data, and 21 to 23 indicate head drive signals 11. ~I4□ data is held, and 24 to 26 are I-1
, ~H,, 27-29 are Hl, ~I1. ．．
The data of each is latched.

As an example, if the head drive output drives a 24-dot thermal head, there are 24 output terminals lie to I1.
．． ．． have.

31 is a latch circuit group that holds one bit string of the current data, 32 holds one bit string of the previous past data, and 33 holds one bit string of the two previous past data. The diagram shows a group of latch circuits that maintain the respective values.

30 is an address decoder for distributing and storing head data in units of 8 bits according to the address information of the data output of the CPU; -For example, the data latch circuit 21 is divided by the bit information of the lower 2 bits 80% A+ of the address data. .24.27 can be selected. Reference numeral 34 denotes a gate circuit that converts a pulse input manually from the energization pulse input terminal into an energization interval signal. This is the pulse generation circuit 18
This is not necessary if the output signal is originally output as a energized section signal.

CI) At the same time that the head drive data is output from U4 to the data bus, the WR multiplied signal is output, and the C
Three terminals are accessed according to the address information defined on the memory map of the PU 4, and data is transferred to each of the data latch circuits 21, 24, and 27 according to the information on the lower two bits of the address bus. Then, the already stored data is transferred to the right side in FIG. 2, for example, data latch circuit 2.
The data of 1 is shifted to the data latch circuit 22 and sequentially stored as past data.

Although it is possible to access up to four de-latch circuits using the lower two bits of information, the number of address input terminals and data latch circuits may be increased in accordance with the number of heating elements.

After the data is set, when a predetermined pulse is manually applied to the energization pulse input terminal 9, the heat generating element is energized.

35. 30 is a gate circuit G0, G, which combines the latched data and the energized period signal to create a heating key control signal that controls the amount of heat generated according to the past history;
, is a signal to the heating elements at both ends ■. , ■1. (The term limit, G, is Il, ~■.

, respectively, are shown to produce the output signals of .

FIG. 3 shows the relationship between the input signal of the energization pulse input terminal 9 and the energization period signal.

T, ~T, is the input waveform of the energizing pulse input terminal 9,
TW and ~TW indicate energization period signals, respectively.

t, ~(, respectively indicate the pulse width of the energization period signal.

FIG. 4 is an explanatory diagram showing the grammar for energizing the thermal head of the print control device according to the present invention.

41, 42, and 43 indicate data in the latch circuits 21, 22, and 23, respectively; 41 indicates the current data, 42 indicates the previous data, and 43 indicates the two previous data. 5152.
53 indicates the output waveform of the head drive signal, and 51 indicates tl. t>j child'), 52 is II x terminal, 5
3 indicates Il and a terminal, respectively.

43 indicates data at the start of printing 1tl.

At the first time of energization, all the energized sections are added to the heat generating element, and this is called the total energization time. If the dot is energized at the previous timing, 3 sections are subtracted as shown by the diagonal line, and if the dot is energized at the two timings before, t8 is shown as the output waveform 52. When the interval is reduced and 0 dots are energized continuously, 1. +1. The interval will be reduced. Furthermore, both dots were energized vertically at the previous timing! As shown in the output waveform 53, i is subtracted by one interval. Further, the energization time is determined by the combination of the above cases. In this method, 2
The configuration is such that it is only necessary to set four current-carrying interval signals for eight past cases (X2X2=8).

The gate circuits G0 and G in FIG. 2 produce this output signal.

If the current to the heating element of the thermal head is small, such as 50 mA or less, use the gate array II.
When forming the CU 3, it is also possible to form the head drive circuit in the same package 111g.

FIG. 5 is a schematic diagram showing one embodiment of a pulse generation circuit,
Fully energized to the heating element! The energization section to be reduced is determined depending on the interval i and the driving history.

60 is an oscillation circuit that includes the thermistor 14 described above, resistors 01, 02.66, INODENS 63, TR/DISTERO 4, inverter 8, Zener diode 05. m HV c formed by the voltage comparator 67
It is connected to the. The period S of this output waveform 69 increases the temperature of the thermal head by +t+Ju, and has a characteristic that it becomes small when the temperature is high and becomes large when the temperature is low. 70 indicates a frequency dividing circuit, and 71 indicates a gate circuit. Gate circuit 71
, each pulse of T. to T is output.

- For example T3 = Se xo, T* = Se x I
OlT.

A time of ==3@X12, T'e=Sex22 is formed. By determining the energization time to the thermal head using such a pulse generation circuit; eight, it is possible to apply the optimum energy to the thermal head and to reduce the past driving time! The applied energy, which is reduced by one cycle, is always correlated to the total energization time at that time, making it possible to improve printing quality.

The frequency dividing circuit 70 and gate circuit 71 in the pulse generation circuit can be integrated into a gate array, and can be further simplified by using a programmable timer.

〔Effect of the invention〕

According to the present invention, data processing by the past driving fat layer is
Since it is not necessary to use the PU, high-speed processing of CI)U becomes possible, and it becomes possible to increase the printing speed of the thermal printer.

In addition, by forming the head heat generation control circuit unit using a gate array and converting it into a single chip, this can be made into a CI).
The data bus allocated on U's memory map is directly connected to the address bus (CI).The configuration is extremely simple, as all that is required is to directly load data from U, making complex processing possible.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of a print control device for a thermal printer according to the present invention. FIG. 2 is a circuit diagram showing an embodiment of the head heat generation control circuit unit of the present invention. FIG. 3 is an explanatory diagram showing the relationship between the energization pulse input signal and the energization interval signal of the head heat generation control circuit unit of the first invention. FIG. 4 is an explanatory diagram showing a method of energizing the thermal hept of the printing control device according to the present invention. FIG. 5 is a circuit diagram of an embodiment of the pulse generation circuit of the printing system 9II apparatus of the present invention. 1... Thermal head 3... Head heat generation control circuit unit 4... Beta PU 18... Pulse generation circuit 14... Thermistor 60... Oscillation circuit and above f/'7 notification J data No. Figure 1T. 3rd v! J 434241 Figure 4

Claims (1)

[Claims] A thermal printer that prints while relatively moving a thermal head having a plurality of heat-generating elements includes a heat-sensitive element that detects the temperature of the thermal head or its surrounding temperature, and a heat-sensitive element that detects the temperature of the thermal head or the surrounding temperature. an oscillation circuit whose oscillation frequency changes accordingly, and a storage means for storing the driving history of each heat generating element of the thermal head at least twice in the past, the total energization time being the basis of the heat generating element; A printing control device for a thermal printer, characterized in that the oscillation circuit determines an energization period within a total energization time before decreasing in accordance with a driving history.