JPS63257657A - High-speed drive method for thermal hard copy equipment - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a high-speed driving method for a thermophobic hard copy device. More specifically, the present invention relates to a method of driving a thermal hard copy device consisting of a coloring type or transfer type thermal printer at high speed in order to cope with an increase in the amount of information processed.

(Background Art) Color-forming or transfer-type thermal printers operate quietly, are small, lightweight, and inexpensive;
It is widely used in hard copy devices such as various printers, copiers, and facsimile machines.

Conventionally, there are two types of thermal printers: a serial head type, which is used in word processors, and a line head type, which is used in facsimile machines. The line head type integrates a single line of heating element, which is the same size as the width of the document, and a driver that drives it.This allows you to print A4 or A4 size sheets by simply feeding the paper, while keeping the head fixed. It is possible to print 84 versions. This line head type achieves higher speed than the serial head type.

For example, a conventional print head with a resolution of 8 lines/l1II has a width of 216 dots and 1728 dots for an A4 size sheet.
It is 84th edition and consists of 256III+ width and 2048 dots. In the conventional line head driving method, all these dots are divided into 8 to 10 dots and time-division driving is performed. This is because, in order to obtain the necessary print density, the current consumption required to flow through the heating element is 10 to 20 mA per dot, and if all dots are to be driven simultaneously, a built-in power supply of several 1 OA is required. Although it is technically possible to incorporate such a large-capacity power supply, it is not a good idea for a thermal printer that is compact, lightweight, and inexpensive.

The fourth one shows the conventional circuit and timing chart.
FIG.

As shown in Figure 4, the 1728-dot heat sensitive body (A)
, and the corresponding driver (a) make up the printer. The time series signal of the 1728 don't shift register (O) is held as one line of data by the latch circuit (1), and the strobe (S>(S, 2)... ...
The pulse train of the signal (S8) and the N
By inputting it to an AND circuit, one line is divided into eight parts (216 dots are one unit). This makes the maximum current 1/8 of the total dot drive current.

As described above, in the case of divided driving, the current value can be reduced, so that the printer can be made inexpensive and compact.

However, in the case of such a conventional device, there was a problem that the speed was low due to the divided drive. That is, although the printing pulse width is high at 1 to 2 m5ec per dot, the speed becomes slower by the number of divisions. For example, if you divide 1728 dots into 8 and drive a 216 dot driver at the same time, the printing speed for one line will be 8 to 1.
It will be 6m5ec. The maximum current consumption at this time is 2.2 ~
It is 4.4A.

The fact that the printing speed becomes slower depending on the number of divisions makes it difficult to cope with an increase in the amount of information, which is a major problem with conventional printer devices.

(Objective of the Invention) This invention was made in view of the above circumstances, and aims to improve the drawbacks of the conventional thermal hard copy device,
It is an object of the present invention to provide a high-speed driving method for a thermal hard copy device that enables high-speed driving of a line head.

(Structure of the Invention) A high-speed driving method for a thermal hard copy device of the present invention includes:
In order to achieve the above objectives, in a thermal hard copy device that uses a thermal head in which a thermal line head and a driver circuit corresponding to each dot are integrated, one line is equipped with a line memory and a control circuit. It is characterized by changing the number of divided drives of the driver in real time according to the light/dark ratio.

The method of the present invention is based on simultaneous driving of all dots, and the number of divided drives of the driver is changed in real time according to the density ratio of one line.

In addition, when all dots are black, for example, in the case of printing lines etc., 10 to 2
If a current of 0 mA is required, a large current of several 1 OA is required in total, which is difficult to handle in reality. and counts the black data and generates a pulse train to be applied to the strobe when it exceeds a certain value and a pulse to change the period of the shift register and latch circuit to perform the necessary divided driving. The speed is increased by providing a memory circuit and a control circuit and performing divided driving only when necessary.

The present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 exemplifies a case in which the driver circuit has a driver circuit consisting of eight units I, like the conventional device. A driver (2) and a NAND circuit (3) are arranged corresponding to a heat sensitive element (1) consisting of 1728 dots. A latch circuit (4), a 1728-dot shift register (5) are arranged, and a strobe is provided corresponding to the common (6). Data (8) and clock (9) are input.

In this configuration similar to the conventional one, in this example, a line memory (10), a counting circuit (11), a comparison circuit (1
2) It has a timing circuit (13) that generates a pulse train of strobe pulses, a shift register, and a pulse that triggers a latch circuit.

In this circuit, basically all dots are driven simultaneously. That is, as shown in Fig. 2, one or more lines of data are stored, and the black data is counted and compared before printing, and if it is less than the reference value, for example 1/8 or less, it is sent as a strobe signal. Pulses corresponding to the print pulse width are generated simultaneously.

The pulses that trigger the latches and shift registers are also synchronous. The box in FIG. 2 shows the printing time for one line.

If the black data is less than the other reference value, for example 1/4
In the following cases, strobe (Sl) (S2) (S3) (S4) and strobe (S5) (S6) (S7) (S8) @: time-divided Pulses are applied to perform 1/2 division driving.

Of course, in ordinary documents, drawings, etc., the black ratio is less than 1/10, and normally all dots are driven simultaneously, and the minimum divided driving is performed only when necessary.In other words, the black ratio , the driving is performed in divisions according to the density ratio of one line. Moreover, this number of divisions is changed in real time.

In this way, it is several times faster than conventional hardcopy devices and can print, for example, 10 to 20 sheets of A4 paper per minute.

(Effects of the Invention) As described in detail above, the present invention enables printing at a much higher speed than conventional thermal hard copy devices. Furthermore, it is small, lightweight, and inexpensive.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram illustrating the method of the present invention. 2 and 3 are signal pulse diagrams for the example of FIG. 1. FIG. 4 is a circuit block diagram of the conventional method. FIG. 5 is a signal pulse diagram in the conventional method. 1... Heat sensitive body, 2... Driver, 3...
NAND circuit, 4...Latch circuit, 5...Dot shift register, 6...Common, 5IS2...
S8... Strobe, 7... Latch, 8...
・Data, 9... Crack, 10... Line memory, 11... Counting circuit, 12... Comparison circuit,
13...timing circuit. Agent Patent Attorney Toshi Nishizawa Mistake 2
:N1 Figure 3 Figure 4

Claims (1)

[Claims] (1) In a thermal hard copy device that uses a thermal head in which a thermal line head and a driver circuit corresponding to each dot are integrated, by being equipped with a line memory and a control circuit, it is possible to A high-speed driving method for a thermal hard copy device characterized by changing the number of divided drives of a driver in real time.