JP2647064B2 - Print control device for thermal printer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a printing control device for a thermal printer, and more particularly to a control circuit for controlling heat generation of a heat generating element.

[0002]

2. Description of the Related Art Conventionally, in a thermal printer, various methods have been used to prevent deterioration of print quality due to heat accumulation during continuous use of a thermal head. Among them, there is a method of determining the energization time by storing previous data for each dot as in Japanese Patent Publication No. 55-48631, and these methods are generally called a history control method. Among these, not a few control their energizing time based on not only their own driving history but also driving data of adjacent heating elements. Representatives of these are disclosed in JP-A-60-1
31262, JP-A-58-67777, and the like.

[0003]

In these prior arts, when referencing adjacent data, it is common to sequentially send data to the drive IC of the thermal head while performing data processing by the CPU. In such a method, even if an attempt is made to operate the thermal printer at a high speed, the processing cannot keep up, and this is an obstacle to speeding up the thermal printer.

In a serial type thermal printer, 2
While 4-dot fonts are becoming more common, there is a vigorous trend toward higher resolutions, such as 32-dot fonts and 48-dot fonts. Unitized thermal head control circuit
Unless it is possible to flexibly cope with such a situation in order to make a chip, a wasteful cost is required.

SUMMARY OF THE INVENTION An object of the present invention is to provide a print control apparatus for a serial type thermal printer which eliminates such conventional problems and is high in speed and excellent in print quality.

Another object of the present invention is to provide a print control apparatus using a head control IC which can be added in accordance with the number of heat generating elements of a thermal head and which can control the energization time in consideration of the influence of adjacent data. Is to do.

[0007]

In order to solve the above-mentioned problems, a print control device for a thermal printer according to the present invention includes a storage circuit for storing current and past drive data of a heating element, and an optional storage circuit connected to the storage circuit. A first gate circuit for increasing / decreasing an energizing time according to its own driving data of the heating element;
And a second gate circuit that increases or decreases the energization time in accordance with drive data of an adjacent heating element.
The storage information at both ends of each storage circuit of the sequentially arranged heating elements is output to another head control IC provided therewith,
And a head control IC in which a plurality of head control ICs are arranged and provided in parallel with each other, the outputs of both ends corresponding to both ends from another head control IC being input to the second gate circuit. By connecting the additional terminals to each other, the energization time of the heating element is controlled based on the driving data of the adjacent heating element.

Further, in the print control apparatus for a thermal printer according to the present invention, the input of the second gate circuit at the non-adjacent end of the head control IC provided side by side is always set to a state where there is no stored information. Features.

[0009]

FIG. 1 shows a head control I according to the present invention.
5 is a schematic diagram illustrating a configuration of a print control device of a thermal printer using C.

Reference numeral 1 denotes a thermal head having a plurality of heating elements 1a, and reference numeral 2 denotes a head drive circuit for driving the thermal head. 3 is a CPU 4 and a thermal head 1
The head control circuit is a head control circuit that is inserted between the ICs and controls the amount of heat generated by the thermal head. Reference numeral 18 denotes a pulse generation circuit for supplying a pulse having two or more types of pulse widths to the head control unit 3, and has a thermistor 14 for detecting the temperature of the thermal head 1 or its surrounding temperature.

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

Hereinafter, the head control unit 3 will be abbreviated as HCU.

The HCU 3 incorporates a data latch circuit, which is a type of storage circuit, and has a data input terminal 5 connected to a data bus 16, an address terminal 6 for inputting lower two bits of an address bus 17, and predetermined address information from the CPU 4. , A chip select terminal (CS terminal) 7, a type of unit select terminal for knowing the designation of the unit, CP
A data latch timing input terminal connected to the WR signal of U4, a plurality of energizing pulse input terminals 9 for determining the energizing time to the heat generating element, and a head drive output terminal for outputting a drive signal to each heat generating element of the thermal head 1. 10 at least.

Reference numeral 11 denotes an HCU based on the address information of the CPU 4.
3 is a decoder for generating a predetermined address code assigned to the address 3.

A ROM 12 stores a control program of the CPU 4, a character generator, and the like.
Reference numeral 15 denotes a power supply.

FIG. 2 is a detailed circuit diagram showing one embodiment of the head control unit HCU3, and the same components as those in FIG. 1 are denoted by the same reference numerals.

The data input terminal 5 can be input to the parallel 8-bit data D ₀ to D _7.

Numerals 21 to 29 denote data latch circuits which hold data of 8 bits, and 21 to 23 hold data of H _{0 to} H ₇ of the head drive signal, and 24 to 26
The data of H ₈ ~H _15, 27~29 are latches data H ₁₆ to H _23, respectively.

For example, the head drive output has 24 output terminals H _{0 to} H ₂₃ for driving a 24-dot thermal head.

Reference numeral 31 denotes a group of latch circuits for holding one dot row of the current head data, 32 denotes one dot row of the past data of one time before, and 33 denotes one dot of the past data of two times before. 2 shows a group of latch circuits each having a dot row.

Reference numeral 30 denotes an address decoder for storing the head data in units of 8 bits according to the address information of the data output of the CPU. As an example, the address decoder 30 uses the bit information of the lower two bits A ₀ and A ₁ of the address data. The latch circuits 21, 24, and 27 can be selected. Reference numeral 34 denotes a gate circuit that converts a pulse input from the energizing pulse input terminal into an energizing section signal. This is unnecessary when the output signal of the pulse generation circuit 18 is originally output as the energized section signal.

At the same time as the head drive data is output from the CPU 4 to the data bus, a WR signal is output, and the CS terminal is accessed by address information previously defined on the memory map of the CPU 4, and the lower 2 bits of the address bus are accessed.
The data latch circuits 21, 24, 2
7 is transferred. Then, the already stored data is shifted rightward in FIG. 2, for example, the data of the data latch circuit 21 is shifted to the data latch circuit 22, and is sequentially held as past data.

Although the lower two bits of information can access up to four data latch circuits, the number of address input terminals and the number of data latch circuits may be increased according to the number of heating elements.

After the data is set, when a predetermined pulse is input to the energizing pulse input terminal 9, energization of the heating element is performed.

Gate circuits G ₀ and G ₁ combine the latched data and the energized section signal to generate a heat control signal for controlling a heat generation amount according to the past history. Gate circuit 37 and a second gate circuit 38. The first gate circuit 37 increases or decreases the energizing time according to its own driving result, and the second gate circuit 38 increases or decreases the energizing time according to the driving result of the adjacent heating element. Wherein G ₁ is a gate circuit, except for sequentially arrayed both ends of the heating element, G ₀ is the gate circuit at both ends. The second gate circuit 38 in G ₀ is
AND circuit 38a, NOR circuit 38b, AND circuit 38
c. The AND circuit 38a refers to whether or not adjacent stored information is in a driving state at the same time. When the HCU 3 is constituted by one thermal head, the AND circuit 38a is essentially unnecessary. However, when the number of heating elements is increased to 32 dots or 48 dots, adjacent drive data must be input from another head control unit in order to arrange two or more head control units.

In this embodiment, the additional terminals 41, 42
When a head control unit is added in accordance with the number of heat generating elements in the thermal head, the ends in adjacent units are controlled in the same manner as those which are not the ends of the same unit, and the driving of the adjacent heat elements is performed. The energization time is determined with reference to the data. Reference numeral 41 denotes an output terminal that is output for reference to another head control unit, and reference numeral 42 denotes an input terminal that inputs stored information from the other head control unit to the second gate circuit 38. Reference numeral 42a denotes a pull-down resistor of the input terminal 42, which is provided to determine that the driving result is "none" when the head control unit is not added.

The operation of the gate circuit at the subsequent stage will be described. The NOR circuit 38b compares the present data with the past driving history.
The circuit 38c functions to reduce a predetermined energizing section.

FIG. 3 shows the relationship between the input signal of the energizing pulse input terminal 9 and the energizing section signal.

T _{0 to} T ₃ are input waveforms of the energizing pulse input terminal 9, and TW _{0 to} TW ₃ indicate energizing section signals, respectively. t _{0 to} t ₃ indicate the pulse widths of the energization section signals, respectively.

FIG. 4 is an explanatory diagram showing a method for energizing the thermal head by the head control unit of the present invention.

Reference numerals 54, 55, and 56 designate latch circuits 21, 2
The data in 2 and 23 are shown, respectively, where 54 is the current data, 55 is the previous data, and 56 is the previous data. 51, 52 and 53 have shown the output waveforms of the head driving signals, 51 of the H ₀ terminal, 52 is a data at the time of 53 H ₅ pin is being driven data 56 respectively start printing H ₂ terminal Is shown. In the first energization, all energization sections are added to the heat generating elements. When energized the dot in the previous timing is reduced is t ₃ period indicated by hatched portion, and energizing the dot in the two previous timing are output waveform 52
As shown by, the t ₂ section is reduced, and when continuous 3-dot energization is performed, the t ₂ + t ₃ section is reduced. Furthermore, when both dots are energized longitudinally previous timing t ₁ period is reduced as shown in the output waveform 53. The energization time is determined by a combination of the above cases. This method has a configuration in which only four energization section signals need to be provided for eight past cases of 2 × 2 × 2 = 8.

The gate circuits G ₀ and G ₁ of FIG. 2 produce this output signal.

The current flow G to the heating element of the thermal head G
If a small current of 50 mA or less is sufficient, the head drive circuit can be formed in the same package when the HCU 3 is formed by the gate array.

FIG. 5 is a schematic diagram showing one embodiment of the pulse generating circuit.

An oscillation circuit 60 including the thermistor 14 includes resistors 61, 62, 66, and a capacitor 6.
3, a power supply V formed by a transistor 64, an inverter 68, a zener diode 65, and a voltage comparator 67.
c. The cycle S ₀ of the output waveform 69 is
It senses the temperature of the thermal head and has a characteristic that when the temperature is high, it is small and when it is low, it is large. 70 indicates a frequency dividing circuit, and 71 indicates a gate circuit.

The gate circuit 71 outputs pulses T _{0 to} T ₃ . As an example, T ₃ = S ₀ × 6,
Times of T ₂ = S ₀ × 10, T ₁ = S ₀ × 12, and T ₀ = S ₀ × 22 are formed. By determining the energizing time to the thermal head using such a pulse generating circuit, the optimum applied energy is always given to the thermal head, and the applied energy reduced by the past driving history always correlated with the total energizing time at that time. And printing quality can be improved.

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

In this embodiment, the temperature of the thermal head is fed back to the energizing time. However, it is also possible to incorporate the thermal head into a power supply to the head and supply a pulse signal from the CPU without using a pulse generating circuit.

FIG. 6 is a schematic diagram of a word processor equipped with a thermal printer using the head control unit of the present invention, and the same components as those in FIG. 1 are denoted by the same reference numerals.

3a is the first HCU and 3b is the second HCU
U, data is mutually exchanged using the additional terminals 41 and 42, and the heat generation elements 1b and 1c at the ends of the connection portion can perform the same heat generation control as the other heat generation elements. 11a, 1
Reference numerals 1b denote address decoders, each of which changes address information to be responded to and can write data separately. Reference numeral 19 denotes a keyboard for inputting character information such as kanji and graphic information.

As described above, it is possible to easily add a head control unit according to the number of heat generating elements of the thermal head.

[0042]

According to the present invention, when controlling the drive energy by referring to the drive data of the dots adjacent to the heating element, a control unit storing the drive data, for example, a head control circuit which is an IC chip is added. However, because the drive data can be exchanged across this control unit, the structure that had to be designed in accordance with the number of heat generating elements in the past was changed to a structure that can be added from the beginning. The development cost and development period were reduced, waste was eliminated, and the thermal head cost was significantly reduced.

Also, since the head control unit is provided with a configuration capable of referring to the drive data of the adjacent dots, even if this type of head drive IC is mounted on a thermal print head, the number of heat generating elements is limited. Instead, the applied energy can be controlled based on the driving data of the adjacent dots, and even if the number of heating elements is large, the printing quality can be greatly improved, and the printing speed and the durability can be greatly improved.

Furthermore, since it can be added and high printing quality can be realized, it can be widely applied not only to serial printers but also to parallel printers and the like.

Furthermore, the range of adjacent dots can be easily expanded not only on both sides but also by the same method, and further improvement in print quality can be expected. "

[Brief description of the drawings]

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

FIG. 2 is a circuit diagram showing an embodiment of a head control unit of the print control device of the thermal printer according to the present invention.

FIG. 3 is an explanatory diagram showing a relationship between an energizing pulse input signal and an energizing section signal of a head control unit of a print control device of a thermal printer according to the present invention.

FIG. 4 is an explanatory diagram showing a method for energizing a thermal head by a head control unit of a print control device of a thermal printer according to the present invention.

FIG. 5 is a schematic diagram of an embodiment of a pulse generation circuit used in a head control unit of a print control device of a thermal printer according to the present invention.

FIG. 6 is a schematic diagram of a word processor using a head control unit of a print control device of a thermal printer according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Thermal head 3 Head control unit 4 CPU 16 Pulse generation circuit 41, 42 Extension terminal

Claims (2)

(57) [Claims] 1. A thermal printer, comprising: a plurality of heating elements; and a storage circuit for storing a driving history of the heating elements, and controlling a current supply time of each of the heating elements based on the storage result. A storage circuit for storing current and past drive data of the heating element, a first gate circuit connected to the storage circuit for increasing / decreasing an energization time by own drive data of an arbitrary heating element, A head control I unitized with at least a second gate circuit for increasing / decreasing energization time according to drive data as a component
C, the head control IC outputs stored information at both ends of the individual storage circuits of the sequentially arranged heating elements to another head control IC provided therewith, and the other head control IC From the corresponding ends of the both ends from the input terminal of the second gate circuit, wherein a plurality of the head control ICs are provided in parallel, and the additional terminals of the head control ICs provided in parallel are provided. A print control device for a thermal printer, wherein the print control devices are connected to each other to control the energization time of the heat generating elements based on drive data of the adjacent heat generating elements. 2. The print control device for a thermal printer according to claim 1, wherein an input of said second gate circuit at a non-adjacent end of said juxtaposed head control IC is always set to a state where there is no stored information. A printing control device for a thermal printer.