JPH04475B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to serial thermal transfer printers.

Conventional technology One of the thermal heads of serial thermal transfer printers
When focusing on one heating element, there are periods in which it is heated and periods in which it is not heated depending on the presence or absence of print data. The period per dot is the reciprocal of the product of the number of characters printed per second and the number of dots per character. For example, if 20 characters are printed per second, each character is 28
If it is composed of dots, 560 dots are printed per second, so the time per dot is 1786 microseconds. The heating necessary for printing one dot is performed every time this time. Hereinafter, this heating repetition time will be referred to as a heating cycle or simply a cycle.

Regarding the control of this heating cycle, in conventional thermal transfer printers, when heating the thermal head, if a heating pulse was applied in the previous heating cycle, the heating pulse width of the current heating cycle is shortened from the regular heating pulse width. It was hot.

Problems to be Solved by the Invention When performing high-speed printing with a thermal transfer printer that performs such control, the temperature of the thermal head cannot be cooled to a temperature at which transfer is no longer possible within one non-heating cycle. Therefore, if characters or symbols that include narrow gaps are printed, the gaps will be lost.

Furthermore, if the heating time is shortened to such an extent that the gaps cannot be filled, there is a problem in that the printing becomes blurred.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides a method for determining whether each heating element of a thermal head has print data of the immediately preceding three dots corresponding to that element and the presence or absence of print data immediately after. It is configured to apply four types of heating pulses with a ratio of 1:0.9-0.7:0.8-0.6:0.5-0.3.

Effects According to the present invention, with the above-described configuration, even when performing high-speed printing, high-quality printing with less blurring of characters can be performed.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a time chart showing the energization pattern of a thermal head of a serial thermal transfer printer according to an embodiment of the present invention, where the solid line represents the energization pattern and the dotted line represents the energization pattern immediately before or after.

In FIG. 1, a, b, c, and d are heating pulses showing the principle of four heating patterns set in one heating cycle.

a is a regular heating pulse.

b is a heating pulse with a time ratio of pulse width to a of 0.8, and heating is not performed during the last 20% of the regular heating time.

c is a heating pulse with a ratio of 0.6 to a;
Do not heat during the first 40% of the regular heating time.

d is a heating pulse with a ratio of 0.4 to a;
Do not heat during the first 40% and last 20% of the regular heating time.

If there is no heating within the previous three cycles or within the immediately following two cycles, heating is performed for the longest time according to the regular heating pattern a.

There was no heating within the previous 3 cycles, and immediately after 2
If heating occurs within the cycle, increase the heating time to 0.8 times the regular heating time according to heating pattern b.

If there is heating within the last three cycles and there is no heating within the immediately following two cycles, the heating time is set to 0.6 times the regular heating time according to heating pattern c.

If heating occurs within the previous three cycles and within the immediately following two cycles, the heating time is set to 0.4 times the regular heating time according to heating pattern d.

With the above configuration, the operation of each pattern will be explained below.

1 If there is no heating within the previous 3 cycles and the immediately following 2 cycles, the longest heating time will be obtained according to pattern a, and sufficient print density will be obtained.

2 If there is no heating within the previous 3 cycles and there is heating within the immediately following 2 cycles, the heating time will be according to pattern b, and if there is heating within the immediately preceding 3 cycles and there is no heating within the immediately following 2 cycles, the heating time will be according to pattern b. , the heating time will be according to pattern c, and if there is heating in either the previous 3 cycles or the immediately following 2 cycles, the heating time will be according to pattern d, and the next heating pulse will be set according to each heating cycle. Since a sufficient non-heating time can be obtained between the dot and the previous heating pulse, the head is cooled to a temperature at which it will not transfer when one dot is vacant, and the print will not be distorted.

Next, FIG. 2 shows a block diagram of a control section of a printer in an embodiment of the present invention. FIG. 3 shows a timing chart for heating a specific thermal head. In this embodiment, a program in a ROM 23 is executed by a CPU (central processing unit) 21 to control the printer. The timer 22 manages heating time and motor speed. CPU2
1 controls the thermal head 26 through the port 25 and driver 25a. Also port 28,
The step motor 29 is also controlled through the driver 28a. Time management of the timer 22 is transmitted to the CPU 21 through an interrupt signal line 27. 23
is a ROM, and 24 is a RAM.

In this example, the heating cycle is 890 μsec. That is, 1120 dots are printed per second. This corresponds to a printing speed of 40 characters per second if each character consists of 28 dots. Heating pattern a, b, c, d
The heating times are 510μs, 390μs, 340μs, respectively.
220 microseconds and their ratio is 1:0.76:0.66:0.43
become. If heating is performed within the previous 3 cycles or within the following 2 cycles, and heating is performed according to pattern c or b, resulting in printing with 1 dot gap, the first dot will be in heating pattern b. , the dots in the middle become the heating pattern d, and the last dot becomes the heating pattern c. As a result, when one dot is empty, the time during which heating is not performed is 1560 microseconds, the thermal head is sufficiently cooled, and the printed characters are not crushed. It can be seen that when the conventional method is used, the non-heating time is 1270 μsec (assuming the normal pulse width is 510 μsec), and the method of the present invention increases the non-heating time by 290 μsec. This prevents the characters from being blurred.

Effects of the Invention As described above, according to the present invention, in a printer that performs high-speed printing, it is possible to obtain high print quality with less blurred characters, and in particular,
When energizing for coloring - non-coloring - coloring, the last of the preceding heating pulse is cut off, and the beginning of the subsequent energizing pulse is cut off, so a large period of non-energizing time corresponding to non-coloring can be provided, ensuring that no coloring occurs. can do.

[Brief explanation of drawings]

FIG. 1 is a time chart showing the energization pattern of the thermal head of a serial thermal transfer printer according to an embodiment of the present invention, FIG. 2 is a block diagram of the control section of the printer according to an embodiment of the present invention, and FIG. This is a time chart for energizing the thermal head of an example printer. 21...CPU, 22...Timer, 25...
Port, 26...Thermal head, 28...Port.

Claims (1)

[Claims] 1. If there is no printing data within the previous 3 cycles and within the 2 cycles immediately after corresponding to each heating element of the thermal head, apply a heating pulse with a time ratio of 1 to the regular heating pulse. If there is print data within the immediately preceding three cycles corresponding to that element, a heating pulse with a time ratio of 0.8 to 0.6 after the first cut is applied, and there is print data within the immediately preceding two cycles corresponding to that element. In this case, the time ratio of the last cut is 0.9 to 0.7
If there is printing data within the previous 3 cycles and within the immediately following 2 cycles corresponding to that element, apply a heating pulse with a cut time ratio of 0.5 to 0.3 at both the beginning and end. A thermal head control method for a serial thermal transfer printer characterized by the following.