JPH04249165A - Thermal printer thermal history control device - 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]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermal history control device for thermal printers of thermal type and thermal transfer type using line thermal heads.

0002

[Prior Art] Conventional thermal printers print by heating a line thermal head for a certain period of time regardless of whether or not there is print data before or after the current line, or print data on the line before and after the current print line. Some were equipped with a heating control means that controlled the heating of the line thermal head by heating voltage and heating time depending on the presence or absence of line printing data and pattern.

0003

[Problems to be Solved by the Invention] However, conventional thermal printers of thermal type and thermal transfer type print by heating the line thermal head for a certain period of time regardless of print data before and after the current line. The temperature of the line thermal head varied due to the print condition of the line, and the density of the print on the current line was not constant, causing problems with print quality. Specifically, when printing is performed on the current line for the first time after no printing was performed on past lines, insufficient heating occurs because the line thermal head is in a cold state. To compensate for the lack of heating, increase the printing time.
If the past line and the current line are printed continuously, overheating will occur. In addition, changing the heating time and voltage depending on whether or not the lines before and after the current line are printed and the pattern takes time to search for print data, calculate the print data, and calculate the heating time and voltage, which is not suitable for high-speed printing. The problem was that it wasn't suitable.

[0004] The present invention aims to solve the above-mentioned problems, and it is possible to achieve high quality printing with no shading without reducing printing speed, and to improve the thermal history of a thermal printer without shortening its life due to excessive heating. The purpose is to provide a control device.

[0005]

[Means for Solving the Problems] In order to achieve the above object, the first means of the present invention is to provide a thermal printer equipped with heating control means and a line thermal head, which includes a storage device for storing print data. , the print data of the current line is input to the arithmetic circuit along with the print data of the past printed line, which is the data of one or more previous lines in the storage device, and the output data of the arithmetic circuit and the print data of the current line are input to the clock signal. By inputting data to the line thermal head in synchronization with the above, heating based on the output data of the arithmetic circuit and heating printing based on the print data of the current line are performed in a time-divided manner within the printing period of one line.

[0006] A second method is to use a thermal printer to sequentially output multiple lines of print data printed in the past from the storage device and simultaneously input it to an arithmetic circuit along with the print data of the current line, and then output the print data from the arithmetic circuit. By synchronizing the multiple output data and the print data of the current line with the clock signal and inputting it to the line thermal head, heating can be performed using the multiple output data output from the arithmetic circuit and heating printing using the print data of the current line. This is done in a time-divided manner within the printing period of one line.

[0007]

[Operation] According to the above-mentioned means, printing is performed after preheating each dot of the line thermal head by changing the number of heating times for each dot within the printing period of one line based on past printing history data. The temperature of each dot of the line thermal head when printing becomes constant, and the print quality is improved without compromising printing speed, and the printing quality is improved. At the same time, the line thermal head can be easily controlled to prevent it from overheating. The lifespan of line thermal printers can be extended.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1A is a block diagram showing the main parts of a thermal printer history control device of a thermal type and a thermal transfer type according to the present invention.

Reference numeral 1 denotes a 16-bit CPU that reads print data stored in a storage device 2 using a dynamic random memory (DRAM). The read print data is input to the arithmetic circuit 3, and the print data to be sent to the line thermal head 4 is selected by the CPU 1. The selected print data is input to the line thermal head 4 in synchronization with the clock signal 5, and thermal printing is performed.

FIG. 2 shows one detailed example of the arithmetic circuit 3. In this embodiment, one word is 160 bits as shown in Figure 3.
, one line has a 640-bit configuration with 40 words, and past print data from three lines before, two lines before, and one line before, and print data from the current line are used.Details of the arithmetic circuit 3 in FIG. For the sake of simplicity, an example of a calculation method for the lower 2 bits of the nth word will be described using the print data of the current line and the print data of the previous line.

Dij represents the j-th print data of one word in the i row before. For example, D000 represents the least significant bit of one word of print data on the current line, and D100 represents the least significant bit of one word of past print data on the previous line. Similarly, D001 represents the second lowest bit of one word of print data of the current line, and D101 represents the second lowest bit of one word of past print data of the previous line.

First, the data of the current row and the previous row outputted from the storage device 2 are latched by the latch circuit 6 using the signal L of the CPU 1, and the logical product of the signal D000 inverted by the inverter 7a and D100 is performed. It is obtained by the AND element 8a and inputted to the selection circuit 9a. Further, D000 is also input to the direct selection circuit 9a. The two input signals are sent to the CPU
1 by the signal S. D001 and D101
are also input to the selection circuit 9b in the same way, and selected by a signal from the CPU 1. The two print data selected by the selection circuits 9a and 9b are converted into serial data in synchronization with the line thermal head serial clock signal by the parallel input/serial output parallel/serial conversion circuit 10 and sent to the line thermal head 4. input.

FIG. 1(B) shows a part of the print data as a model diagram, where the white area is the data 0, that is, the area where no printing is performed, and the diagonally shaded area is the data 1.
This is the part that is printed. (a) is past print data from three lines ago, (b) is past print data from two lines before, (c) is past print data from one line before, and (d)
is the print data of the current line, and (e), (f) and (
g) is print data after calculation by the calculation circuit 3.

First, by the read cycle of CPU1, print data 1 from D000 to D015 of the current line is read.
6-bit data is read from the storage device 2. The data is latched with the signal L of CPU1, and then the past print data D10 of one line before the time after the same read cycle is
Read D115 from 0, latch, D200 to D215
is read and latched, D300 to D315 are read and latched, and then the calculation is completed in real time and input to the selection circuit similar to 9a or 9b. The selection circuit selects (e), which is the calculation result of the print data (a) from three lines before and the print data (d) from the current line, using the signal S of the CPU 1, and converts it into serial data by the parallel-serial conversion circuit 10. and is input to the line thermal head 4 in synchronization with the clock signal 5. This is repeated and heated for 40 words.

Next, select (f) which is the calculation result of the print data of two lines before (b) and the print data of the current line (d), convert it to serial data by the parallel-serial converter circuit 10, and convert it to line thermal data. The clock signal 5 is input to the head 4 in synchronization with the clock signal 5. This is repeated and heated for 40 words. The print data of the previous line (c) and the print data of the current line (
The calculation result (g) of step d) is selected, converted into serial data by the parallel-serial conversion circuit 10, and inputted to the line thermal head 4 in synchronization with the clock signal 5. This is repeated and heated for 40 words. Finally, the print data (d) of the current line is selected, converted into serial data by the parallel-serial conversion circuit 10, and inputted to the line thermal head 4 in synchronization with the clock signal 5 for printing. This is repeatedly heated and printed for 40 words. In other words, the print dots of the current line are heated except for the dots that were heated for printing three lines ago, then the print dots of the current line are heated except for the dots that were heated for printing two lines before, and then the print dots of the current line are heated for one more line. Heats the print dots in the current line except for the previously print heated dots. Finally, the current line is heated and printed. After preheating three times and heating printing once, the paper is advanced to the next line and the next line is heated. 3 lines ago, 2 lines ago,
Dots whose data was 0 in the previous row are heated 4 times to prevent insufficient heating.
For dots whose data was 1 in the previous row, heating is performed only once, thereby extending the life of the head.

In addition, in this embodiment, data is selected using the signal S from the CPU 1, and data is latched using the L signal, but a circuit for generating the signals S and L may be provided within the history control circuit.

[0018]

Effects of the Invention As described above, according to the present invention, printing data of a plurality of past dots can be stored and recorded with a small amount of additional circuitry without using an additional storage device for history control.
By performing calculations with the print data of multiple dots on the current line, the
Since printing is performed by changing the number of heating times for each dot of the line thermal head within the printing period of one line, the temperature of each dot of the line thermal head when printing is constant without reducing the printing speed, and the density of printing is improved. This improves print quality, and since the head is not overheated, the lifespan of the line thermal printer can be extended.

[Brief explanation of the drawing]

[Fig. 1] (A) is a block diagram of the main parts of a thermal history control device for a thermal printer according to the present invention; (B) shows an example of print data of past lines, print data of the current line, and print data after calculation; model diagram

[Fig. 2] A circuit diagram showing an example of an arithmetic circuit in the control device of the present invention.

[Figure 3] Configuration diagram of print data

[Explanation of symbols]

2. Storage device 3 Arithmetic circuit 4 Line thermal head 5 Clock signal

Claims (2)

[Claims] Claim 1: A thermal printer equipped with a heating control means and a line thermal head, comprising a storage device for storing print data, and print data of a previously printed line, which is data of one or more previous lines in the storage device. At the same time, the print data of the current line is input to the arithmetic circuit, and the output data of the arithmetic circuit and the print data of the current line are synchronized with the clock signal and input to the line thermal head. A thermal history control device for a thermal printer that performs heat printing based on line print data in a time-divided manner within the printing period of one line. 2. A thermal printer equipped with a heating control means and a line thermal head, which has a storage device for storing print data, and sequentially outputs multiple lines of print data printed in the past from the storage device while printing the current line. The output data from the arithmetic circuit is simultaneously input to the arithmetic circuit along with the print data of A thermal history control device for a thermal printer that performs heating using a plurality of output data and heating printing using print data of the current line in a time-divided manner within a printing period of one line.