JPH0829600B2 - Print control device for thermal printer - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal printer, and more particularly to history control for controlling heat generation according to the driving results of its heat generating elements.

[Conventional technology]

Conventionally, in a thermal printer, in order to suppress deterioration of print quality due to heat accumulation during continuous driving of the thermal head,
A print control method called a history control method in which past drive history is stored and the applied energy of the thermal head is controlled in accordance with the history has been used. As one example of these,
58-49279, JP-A-58-67477, JP-A-59-150768 and the like.

[Problems to be solved by the invention]

In these conventional examples, generally, data for history control is created by a data processing circuit as in JP-A-59-150768, and this data is sequentially sent to the drive IC of the thermal head.
The method of printing while exchanging data was common. In such a system, even if an attempt is made to operate the thermal printer at high speed, the processing cannot catch up, which is an obstacle to speeding up.

Further, as seen in JP-A-58-49279, JP-A-58-67477, JP-A-59-150768, etc., the energization time corresponds to the current drive data by referring to past history and adjacent dots. When dividing and outputting to the one that refers to past drive data etc., it is not possible to flexibly change the composition ratio of the energization time according to the printing mode and printing speed such as ink ribbon difference and printing with thermal paper Therefore, there is a problem that it is necessary to limit the ink ribbon and the printing speed.

SUMMARY OF THE INVENTION An object of the present invention is to provide a print control device for a thermal printer, which eliminates the above-mentioned conventional problems, can cope with various print media, and has excellent print quality.

Another object of the present invention is to minimize the transfer of drive data during printing when referencing past stored data, remove the obstacle of speeding up, and energize a large number of divided heads with a simple configuration. It is an object of the present invention to provide a print control device for a thermal printer that provides a configuration capable of sending out time, and thereby makes it possible to speed up a serial thermal printer.

[Means for solving problems]

A print control device for a thermal printer according to the present invention stores a current and past drive data of a heat generating element, and can directly output individual storage data, and an energization of any heat generating element connected to the memory circuit. A gate circuit that outputs the time by dividing it into a main energization time for outputting the current drive data and a plurality of energization times for outputting data corresponding to past drive data, and a main energization time and a sub-energization time. The reference means stored in the recording circuit and corresponding to a plurality of print modes and showing the proportional relationship with the reference current means for setting a plurality of current-carrying sections in the gate circuit. Energization signal output means for modulating and outputting a periodic signal indicating the start and end, and demodulating the signal of the energization signal output means to output individual energization time having a time width corresponding to each cycle. And having a conduction period signal generating circuit to be supplied to the gate circuit as a conductive section signal and a head drive circuit that turns on and off the current supply to the heating element in response to an output signal of the gate circuit.

〔Example〕

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

1 is a thermal head having a plurality of heat generating elements 1a, 2 is a head drive circuit for driving this thermal head, 3 is a head control circuit which is inserted between the CPU 4 and the thermal head, and which controls the heat generation amount of the thermal head for each dot (Hereinafter abbreviated as HCU), 15 has a thermistor 19 that detects the ambient temperature of the thermal head 1 or the substrate temperature, and CP
A reference pulse generation circuit that generates a pulse in synchronization with the TRIG input from U4 and determines the reference amount of energization time to the heating element,
12 is a ROM, 13 is a RAM, 17 is a data bus, 18 is an address bus, 14 is a timer circuit built in the CPU 4, measuring means for measuring the pulse width of the reference pulse generating circuit 15, and 20 is a power supply.
Vh input terminals are shown.

CPU4 indicates an 8-bit CPU as an example.
It has a terminal 8, an I / O port, a timer circuit 14, and the like.

The HCU 3 functions as a type of peripheral of a CPU as a unit circuit, and is assigned to a specific address on a memory map like the ROM 12 and the RAM 13. The decoder 16 is connected to the terminal 7 for accessing this unit circuit.
5 is a data input terminal connected to the data bus 17, 6 is an address input terminal for inputting the lower 2 bits of the address bus, 9 and 10 are for determining the energization time of the heat generating element 1a,
The energization signal input terminal will be described in detail with reference to FIG.

FIG. 5 is a circuit diagram of an embodiment of the reference pulse generating circuit 15.

The resistors 61 and 62 form a reference potential generation circuit by the thermistor 19, and the transistor 64, the capacitor 63, and the resistor 65 form a charge / discharge circuit. Reference numeral 66 is a voltage comparison circuit, and 67 is an output pull-up resistor.

When a signal is input from the CPU to the TRIG input terminal 15a, the output terminal 15b outputs a pulse waveform having a pulse width TW corresponding to the temperature of the thermal head by the operation of the thermistor 19. The CPU 4 can measure this using the timer circuit 14 and obtain the reference energization time to the heat generating element installed in the thermal head.

FIG. 2 is a head control circuit of a print control device according to the present invention.
FIG. 3 is a detailed circuit diagram of HCU3.

The data input terminal 5 can input 8-bit data of D _{0 to} D ₇ in parallel.

21 to 29 shows a data latch circuit to hold 8-bit data, respectively, 21 to 23 of the head drive signals H ₀ to H ₇
Data holds, 24-26 data H ₈ to H _15, from 27 to 2
9 is latching data of H ₁₆ to H _23, respectively.

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

Reference numeral 31 denotes a latch circuit group for holding one dot row of the current head data, 32 denotes one dot row of the previous data of one time before, and 33 denotes one dot row of the past data of two times before. Are shown in FIG.

Reference numeral 30 is an address decoder for storing head data by dividing it into 8-bits according to the address information of the data output of the CPU, and as an example, the lower 2 bits of the address data, a data latch circuit according to the bit information of A ₀ and A _1.
21, 24, 27 can be selected.

At the same time as the head drive data is output from the CPU 4 to the data bus, the ▲ ▼ signal is output.
The terminal is accessed, and data is transferred to each of the data latch circuits 21, 24 and 27 by the information of the lower two bits of the address bus. 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 sequentially stored as past data. The data latch circuit is configured such that all stored data can be directly output for each bit, and when referring to past data, the output of the data latch circuit storing the current data is directly compared with the gate circuit. It is possible.

Although it is possible to access up to four data latch circuits with the information of the lower 2 bits, the number of address input terminals and the number of data latch circuits may be increased according to the number of heat generating elements. After the data is set, when a predetermined pulse is input to the energization signal input terminals 9 and 10, the heat generating element is energized.

34 is an energization section signal generation circuit for demodulating an energization signal modulated into a periodic signal from the CPU 4 as an energization section signal,
It is composed of a binary counter 35, an inverter 35a, and an AND circuit 35b. Reference numeral 9 is a clock input terminal of the binary counter, and 10 is a reset input terminal. The clock input is
The energization section signal generation circuit 34 is a signal transferred with a variable cycle, and selectively extracts the cycle to create a section signal.

FIG. 3 shows input / output waveforms of the energization section signal generating circuit. Reference numeral 41 represents a reset input waveform, and 42 represents a clock input waveform, that is, an output waveform of the energization signal output means. The output waveform of the energization signal output means is such that its cycle changes sequentially corresponding to the pulse width of each energization section calculated separately, and becomes a periodic signal indicating the start and end of each energization time. Is. When the binary counter 35 receives this clock after reset input, it is converted into a 4-bit code. This is converted into output waveforms of 43 to 46 by the inverter 35a and the AND circuit 35b. 43 shows the output waveform of the 36a terminal, 44 shows the output waveform of the 36b terminal, 45 shows the output waveform of the 36c terminal, 46 shows the output waveform of the 35d terminal, and their pulse widths are t ₃ , t ₂ , t ₁ , t _{0, respectively.} Is. These pulse widths are the energizing time of the heating element, and are given to the heating element as an energizing section corresponding to the past drive history.

FIG. 6 is an explanatory view showing an example of the contents of the reference means for referring to the ratio of the energized sections.

As an example, t ₀ in the thermal transfer printing mode is set to 100 and the respective proportional relationships are shown. This ratio can be changed or added according to the type of ink ribbon or the type of printing paper. Set this ratio as a table in ROM12,
Each energization time can be obtained according to the print mode and print speed from the separately set reference value and the value in the table. Further, the calculation becomes easy by using the output pulse width of the reference pulse generating circuit as the reference value. As described above, the pulse width TW of the reference pulse generating circuit can be set to a value for obtaining the main energization section t ₀ , but it is also possible to obtain the pulse width TW by dividing the total field time by TW and dividing it by the energization section ratio. At this time, a switching circuit may be added to the reference pulse generation circuit 15 so that the output pulse width can be varied depending on the printing mode or the like.

The gate circuit 37 (GO) in FIG.
34, and outputs a head drive signal to the heating element by mixing the output signal of 34 with the drive data of the storage circuit. The first gate circuit 38 corresponding to the past drive data and the first gate circuit 38 corresponding to the current drive data are output. A second gate circuit 40 and a third gate circuit 39 for applying a preheating pulse according to the past driving history. The energizing sections t ₃ , t ₂ and t ₁ are sub-energizing sections corresponding to past drive data and are input to the first gate circuit, and the energizing section t ₀ is a main energizing section corresponding to current drive data and 2 is input to the gate circuit. Of the sub-energization section, t ₂ is also input to the third gate circuit for the preheat pulse.

〔motion〕

The timer circuit 14 reads the pulse width TW corresponding to the temperature of the thermal head by the reference pulse generation circuit 15 of FIG. Next, the CPU 4 calculates the pulse width of each of the main energizing section and the sub-energizing section to the heat generating element according to this, and processes this by the energization signal output terminal 4a which is the output terminal of the built-in I / O port. It outputs as a periodic signal using a timer circuit. The CPU 4 also serves as the energization signal output means. The pulse width TW is read at each printing energization cycle, and by accommodating the ever-changing temperature of the thermal head, heat accumulation can be prevented and good print quality can be realized.

FIG. 4 is an explanatory view showing a method for energizing the thermal head of the print control device according to the present invention. 51, 52, 53 show data in the storage circuits 31, 32, 33, respectively, I indicates ON data, O indicates off data, 51 indicates current data, 52 indicates data of the previous time, and 53 indicates data of the previous time. 54 ~ 58
Is shows the output waveforms of the head driving signal, the H ₀ terminal 54, 55 of the H ₂ terminal, 56 a H ₅ terminal, 57 is the H ₇ terminals, 58
The output waveforms of the H ₁₀ terminal are shown.

In FIG. 4, 53 is shown as data at the start of printing. Energization The dots that are energized for the first time are energized in all energization periods. The entire energization time is applied, and the dots that are energized are t ₁
The section is applied as a preheat pulse. This preheating pulse only raises the substrate temperature of the thermistor and does not form dots.

If the energization data of its own heat generating element is ON at the previous timing, the t ₃ section indicated by the shaded area is reduced (shown in the output waveform 54), and if there is drive data at the previous timing t ₂ The interval is reduced (shown in output waveform 57) and if it is continuous, the t ₃ + t ₂ interval is reduced (shown in output waveform 54). In the previous drive result, when both the adjacent dots are energized, the t ₁ section is reduced (shown in the output waveform 56). And when its current data is on the data to be compared in an attempt to all reduction be on data, only t ₀ interval is energized on. Conversely, when the data to be compared for the reduction is the off data and the current data is off, a preheating pulse is given. The gate circuit 37 performs such comparison of drive data and selection of energization section.

By forming the head control circuit 2 as a gate array into one chip, a thermal printer having an extremely simple configuration can be realized. This is a very important factor when incorporating not only a terminal printer using a thermal printer but also a miniaturized device such as a portable word processor.

In the present embodiment, as an example, an example in which past data is stored up to twice before is shown. However, the number of sub energization sections can be increased to four or five times as three or four times. By doing so, more detailed history control can be realized.

In addition, the CPU 4 outputs the energization signal according to the type of the ink ribbon and the type of paper, and changes the width of the energization interval and the energization interval for convenience. Are stored in the ROM 12, and are converted into readout cycle signals corresponding to the print mode and output.

〔The invention's effect〕

According to the present invention, it is not necessary to process data by past drive data in a data processing circuit such as a CPU as generally seen in conventional examples, and it is not necessary to process this data while sequentially replacing it, Since the stored state can be used as it is, the processing speed of the CPU is increased, the processing speed of the thermal printer as a whole is increased, and eventually the printing speed is increased.

In addition, since the energization period signal that divides the energization period is output as a periodic signal corresponding to this energization period, there is no limitation on the combination of pulse widths of the energization period, and the optimal energization time corresponding to various print modes and printing speeds. Since the ratio can be selected and set easily, it can be widely applied to thermal transfer printers or thermal printers. Conventionally, it was difficult to share a thermal transfer printer with a printer compatible with thermal paper. Since the optimum control method can be selected, it is possible to use a single printer.

Further, all the energized sections can be generated by the modulated periodic signal and the reset signal, and it is possible to easily cope with the increase in the number of storage circuits and the increase in the number of times the past drive history is referred to. Can be further improved.

As described above in detail, the print control device for a thermal printer according to the present invention is extremely useful because it can be applied to any type of printer that prints using a heat generating element.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an embodiment of a terminal printer using a print control device of a thermal printer according to the present invention. FIG. 2 is a detailed circuit diagram of a head control circuit HCU3 of the print control device of the present invention. FIG. 3 is an explanatory diagram showing input / output waveforms of a conduction section signal generation circuit of the print control device of the present invention. FIG. 4 is an explanatory diagram showing a method of energizing the thermal head of the print control apparatus of the present invention. FIG. 5 is a circuit diagram of an embodiment of a reference pulse generating circuit used in the print control device of the present invention. FIG. 6 is an explanatory view showing an example of the contents of a reference means for referring to the ratio of energized sections. 1 …… Therma head 2 …… Head drive circuit 31, 32, 33 …… Memory circuit 4 …… Energization signal output means, CPU 15 …… Reference pulse generation circuit 14 …… Timer circuit 34 …… Energization section signal generation circuit 37 ...... Gate circuit

Claims (1)

[Claims] 1. A thermal printer that prints on plain paper via a thermal paper or a thermal transfer ribbon using a thermal head having a plurality of heating elements, and stores past driving history of the heating elements. In a thermal printer such as controlling the energization time of each of the heat generating elements based on the storage result, a storage circuit that stores the current and past drive data of the heat generating elements and can directly output the individual storage data. Dividing the energization time of any heat generating element connected to the memory circuit into a main energization time for outputting the current drive data and a plurality of sub-energization times for outputting the data corresponding to the past drive data. A gate circuit for outputting the main power supply time and the sub power supply time, and a reference means which is stored in a memory circuit and corresponds to a plurality of print modes; An energization signal output means for modulating and outputting to a periodic signal indicating the start and end of each energization time according to each energization time obtained by referring to the reference means for setting the plurality of energization sections in the automatic circuit, An energization interval signal generating circuit that demodulates the signal of the energization signal output means and outputs individual energization times having a time width corresponding to each cycle to give to the gate circuit as an energization interval signal, and a response to the output signal of the gate circuit And a head drive circuit for turning on and off the power supply to the heat generating element.