JPH02225058A - Thermal recorder - Google Patents

Abstract

PURPOSE:To enable correction of printing density to be simply performed by a method wherein cycle is measured and at the same time, a number of black pigments in a printing data per one line to be recorded is counted, and applying time of voltage to a thermal head is controlled based on this number of black pigment and the cycle. CONSTITUTION:A number of black pigment in a printing data of a line to be printed is counted with a black pigment number counter 4 and, a cycle from end of preceeding line printing to start of next line printing is measured with a cycle counter 2. When the cycle is not long, applied time of a length corresponding to the measured cycle is established to a thermal head 1. When a period is a long cycle control period, the number of black pigments after end of the long cycle is judged. When the number is a specific number or more, since the thermal head 1 was heated for specific time or longer on the preceding time, corresponding ordinary applied time is determined. Further, when the number of black pigments is not a specific number or more, judgement of the number of black pigments on the further previous line is performed. When the specific number or more, corresponding applied time is determined. When the number of black pigments is not the specific number or more on the previous line, printing time for the thermal head 1 is established longer than ordinary time, and printing is performed.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a thermal recording device that prints on thermal recording paper using a thermal head.

[Conventional technology]

FIG. 5 shows a block circuit diagram of a conventional thermal recording device,
In the figure, 1 is a thermal head, 2 is a cycle counter that measures the cycle from the end of printing on the previous line to the start of printing on the next line, and 3 is a control means that controls the voltage application time of the thermal head from the cycle determined by the cycle counter 2. This is the microcomputer control section. Next, the operation will be explained. The microcomputer control unit 3 determines the voltage application time for printing the next line of the thermal head 1 based on the period measured by the period counter 2, and controls printing on the thermal recording paper. In this case, the application time of the voltage is determined according to the temperature of the thermal head l at that time, so the longer the period from the end of printing the previous line to the start of printing the next line, the more heat-sensitive the printing of the previous line is. The thermal head 1 is naturally cooled before moving to the next line, and the voltage application time for printing the next line must be long, and when the period exceeds a certain length, the application time is , we will call the period at this time, which is fixed at a certain period of time, a long period.

[Problem to be solved by the invention]

Since the conventional thermal recording device is configured as described above, in the case of roJ where there are no black pixels to be printed on the next line immediately after the long cycle is measured, the thermal head 1 will move on to the next line of printing without being heated, but since the previous line has been printed, printing will start in an extremely short cycle. . The recording conditions for this line should be exactly the same as the line after the previous long cycle, but since a short cycle was measured this time, the application time to the thermal head was extremely short. A problem sometimes occurred in that sufficient print density could not be obtained. This invention was made to solve the above-mentioned problems, and its purpose is to provide a thermal recording device that can obtain sufficient print density even after long-period detection, and that can always provide a reliable print condition. shall be.

[Means to solve the problem]

The thermal recording device according to the present invention measures the period, counts the number of black pixels in the print data for each line to be recorded, and applies the voltage to the thermal head based on the number of black pixels and the period. It was designed to be controlled.

[For use]

In the thermal recording device according to the present invention, when a long cycle is measured, the application time to the thermal head is increased until the number of black pixels exceeds a certain number at that time, and the print density is increased. to correct.

【Example】

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, 1 is a thermal head, 2 is a cycle counter, 3 is a microcomputer control unit as a control means, and 4 is a black pixel number counter that counts the number of black pixels in print data for each line to be recorded. Based on the cycle measured by the cycle counter 2 and the number of black pixels counted by the black pixel number counter 4, the microcomputer control unit 3 determines that the number of black pixels in the next printing line is constant when a long cycle is measured. Until the value exceeds the value, printing control is performed to correct the printing density by increasing the voltage application time to the thermal head 1. Next, the operation will be explained. The flowchart in FIG. 2 is the control for the second and subsequent lines after the end of the long cycle, but in steps STI and ST2, the black pixel number counter 4 counts the number of black pixels in the print data of the next line to be printed. Furthermore, the cycle counter 2 measures the cycle from the end of printing on the previous line to the start of printing on the next line. Next, in step ST3, the microcomputer control unit 3 determines whether or not it is a long cycle control period, and if it is not a long cycle, the microcomputer control unit 3 applies an application period corresponding to the measured cycle to the thermal head 1 in step ST7. The next line is printed by the thermal head 1 in step ST8. On the other hand, if it is a long cycle control period, the process proceeds to step ST4, where it is determined whether the number of black pixels after the end of the long cycle is greater than or equal to a certain number, and if it is greater than or equal to the certain number, the thermal head l is Since it has been heated for more than a certain time, the current corresponding normal application time is determined in step ST7. Furthermore, in step ST4, if the number of black pixels is not a certain number or more, the process proceeds to step ST5, where it is further determined whether the number of black pixels in the previous line was more than a certain number. If the number of black pixels is greater than a certain number, the corresponding application time is determined in step ST7, while if the number of black pixels for the previous line is not greater than a certain number, it is determined that the thermal head 1 has been naturally cooled for a considerably long time. Therefore, the process proceeds to step ST6, where the application time to the thermal head 1 is set longer than usual, and printing is performed. In addition, step ST
At step 7, the long cycle control period is canceled. The flowcharts of FIGS. 3 and 4 explain the printing operation of other embodiments, that is, these other embodiments:
In the example shown in Fig. 2, the application time of the thermal head is controlled to be longer than usual after a long period is detected, but even in the case of a short period, the number of black pixels under a certain convergence is If the printing status continues for more than the specified number of lines (
(Figure 3), or if it continues for more than the specified time (Figure 4)
Figure 2) also attempts to correct the print density by increasing the application time of the thermal head. That is, in the flowchart of FIG. 3, step 5
Even when the processing of T13 and 5T14 is short cycle,
When the number of black pixels below a certain number is printed for a specified number of lines, the thermal head 1 is naturally cooled, so the application time is made longer than usual. In addition, steps 5TII, 5T12, 5T15, 5T16
is the corresponding step in the flowchart of Fig. 2, that is, S
Tl, Sr1. Sr7. The processing is the same as Sr8. On the other hand, in the flowchart of FIG.
Even if the processing of T23 and 5T24 is performed in a short cycle, when printing with a black pixel number below a certain number continues for a specified time or more, the thermal head l is assumed to be naturally cooled, and Set the application time longer than usual. Note that steps 5T21, 5T22, 5T25, and 5T26 are the second
The corresponding steps in the flowchart of the figure, namely STI,
Sr1, Sr7. The processing is the same as Sr8.

【Effect of the invention】

As described above, according to the present invention, the thermal recording device can be set to the thermal head based on the cycle from the end of printing of the previous line to the start of printing of the next line and the number of black pixels in the print data for each line to be recorded. The voltage application time is controlled, that is, after long-period detection, the voltage application time is extended until the number of black pixels exceeds a certain number, so the print density can be easily corrected and always This has the effect of providing optimal printing conditions.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a thermal recording device according to an embodiment of the present invention, and FIG. 2 is a flowchart of its printing operation.
3 and 4 are flowcharts of printing operations in other embodiments, and FIG. 5 is a block circuit diagram of a conventional thermal recording apparatus. 1 is a thermal head, 2 is a cycle counter, 3 is a control means (microcomputer control unit), and 4 is a black pixel number counter. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent applicant: Mitsubishi Electric Corporation (2 others)

Claims (1)

[Claims] In a thermal recording device that prints on thermal recording paper using a thermal head, there is a period counter that measures the period from the end of printing on the previous line to the start of printing on the next line, and a period counter that counts the number of black pixels in the print data for each recorded line. a black pixel number counter and a period measured by the period counter;
and a control means for controlling the voltage application time of the thermal head for printing the next line based on the number of black pixels counted by the black pixel number counter.