JPH0371861A - Thermal printing 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 Field of Industrial Application The present invention relates to a thermal printing apparatus that prints images using a thermal head.

Conventional technology In the prior art, a digital video signal from an external device, such as a personal computer, is sent to one of the thermal heads.
Line by line, reference numbers #O, #1 in FIG. 4 (1). #2
．． Assuming that the data is transferred sequentially in the order of #3, and each transfer time is T1, each of the plurality of resistive heating elements of the thermal head provided in the thermal printing device will simultaneously transfer data for one line. When the print is energized and displays a binary value,
For example, in order to print data #1, as shown in Figure 4 (2), the heat generating resistor is energized for the energizing time Wl, and the heat generating resistor is energized for the rest time W2 (however, W2 = TiWl). It is not supplied and is in a de-energized state.

FIG. 5 is a graph showing the thermal characteristics of the thermal head. Assuming that the energization time Wl of the heat generating resistor provided in the thermal head is constant, when the dead time W2 is relatively long, the temperature of the heat generating resistor will change as the rest time is indicated by the reference mark W 2 a. Compared to the short case shown,
This temperature is low.

Therefore, at the time of transfer described in connection with FIG. 4 above, rWj
When Tl is long, the rest time W2 is long, and therefore the temperature of the heating resistor of the thermal head is relatively low.
As a result, the print density becomes lighter. Further, when the transfer time T1 is short, the pause time W2 is
As shown in , the temperature of the heating resistor increases and the printing density increases. In this way, there is a problem in that the print density changes depending on the length of the transfer time T1.

Problems to be Solved by the Invention An object of the present invention is to print a print W! regardless of the transfer time of the video signal to be printed. An object of the present invention is to provide a thermal printing device that can optimize i density.

Means for Solving the Problems The present invention provides a thermal head having a plurality of heating resistors as one line, a video signal generation source that generates a video signal to be printed, and a video signal that is transferred from the video signal generation source. at least 1
a memory for storing a line, a means for applying electric power r= to one line's worth of heating resistors all at once in relation to the transfer motion t' based on the stored contents of the memory; and one line by a power energizing means. 2. A thermal printing apparatus characterized by comprising means for variably setting an energization time of minutes.

According to the present invention, at least one line of the video signal is transferred from the video signal generation source and stored in the memory, and based on the stored contents of the memory, the plurality of heating resistors for one line of the thermal head are transferred. When printing a binary video signal without nine gradations, one or more heating resistors are simultaneously energized for the same amount of time.

This energization time can be varied and adjusted by the setting means. Therefore, 1 from the video signal source to the memory
If it takes a long time to transfer the line's worth of video signals, set the energization time longer.

In addition, when the transfer time is short and the transfer is at high speed, the energization time is set short to prevent the temperature of the heat generating resistor from rising too much due to heat accumulation. In this way, the printing density can be optimized regardless of the length of the transfer time.

When performing multiple illumination printing, the heating resistors to be energized with power for one line start energizing power at the same time,
The energization time is set for each heating resistor for the time corresponding to the gradation, and the energization time corresponding to this gradation is set longer when the transfer time is long and shorter when the transfer time is short. Print density can be maintained optimally regardless of the length of transfer time.

When the run-on transfer time is shorter and the required energization time is therefore longer than the transfer time, the heating resistor is energized for the required energization time, and then power is supplied to the resistance heating element for a predetermined rest period. First, it is preferable to cool the device to prevent heat accumulation as much as possible, and then perform the next transfer of the video signal.

Embodiment FIG. 1 is a block diagram of an embodiment of the present invention. A digital video signal from an external device 1 such as a personal computer is sent via line 2, one line at a time, as shown in FIG. 2 (1).

The signals are generated sequentially during the transfer time Tll and input to the parallel interface circuit 3. This video signal for each line is referred to as Rrl-1, n, n+1 in FIG. 2 (1).
．． ...is shown. This external device 1 connects the parallel interface circuit 3 to the line 4 as shown in FIG.
When the operation (busy) signal indicated by 2> is at a low level, one line of video signal (m dots) is transferred as described above. In addition, a strobe signal shown in FIG. 2 (3) is generated from the external device 1 to the line 5.
In synchronization with the usy signal, when this strobe signal is at a low level, the parallel interface circuit 3
Then, the video signal shown in FIG. 2 (4) is derived. The video signal derived to this line is as shown in FIG. 2 (4).
S reference φ, 1. . . m, which corresponds to one line of the video signal shown in FIG. 2 (1). Data selector 7 connects and derives the video signal from line 6 to output line 8 in order to print the video signal from external device 1 . The video signal from this line 8 is applied to a thermal head 10 via a printing control circuit 9.

In the thermal head 10, a plurality of heating resistors R1 to Rm for one line are provided, and these heating resistors R1
Power is supplied to ~Rm via driving transistors Q1 to Qm. Transistors Q1 to Qm are given signals from individually corresponding AND gates 01 to 0m, and one input of the AND gates 61 to Gm receives an energization control signal from the print control circuit 9 via line 21. Given. This energization control signal is configured to have a value determined by the setting means 12.

In the thermal head 10, the binary video signal for one line to be printed is sent to a shift register 23 via a line 22.
When the binary video signal for one line is stored in the shift register 23,
Latch circuit 2 in response to a latch signal via line 25
The stored contents of cells C1 and Cm of the shift register 23 are given to cells C11 to C1rn of 4 and latched.The binary data for one latch of these cells C11 and C1m is the other of 01 to 0m (AND game). given to the input of

In the latch circuit 24, the stored contents of each cell C11 to C1m are held during the transfer time Tll.

The energization control signal derived from the line 21 is set to be at a high level for the energization time Wll shown in FIG. 2 (5) for the heating resistors R1 to Rm.
ll increases as the transfer time Tll becomes longer as shown in FIG.
The setting means 12 sets so that the energization time Wll becomes shorter as l becomes shorter. The setting means 12 has one or more dip switches 13a, and the operator sets the energization time Wll in correspondence with the transfer time Tll by selectively turning on/off the dip switches 13a. The output from the setting means 12 is given to a timing circuit 13 realized by a microcomputer or the like.
Based on the timing signal given to the thermal head 10, the print control circuit 9 derives a signal that remains at a high level for the above-mentioned energization time Wit and supplies it to the thermal head 10. This energization control signal has a pause time W12 (however, W12=Tll-Wll
) is at a low level, and during this time W12, the heating resistors R1 to Rm are not energized and are in a non-energized state, and cooling is performed.

Abnormal heat accumulation is prevented.

Timing circuit 13 also provides timing signals to parallel interface circuit 3 via line 15 and select signals to data selector 7 via line 16 to control its operation.

In this way, even if the transfer speed of one line of digital video signals of the external device 1 is different, thermal printing can be performed with the optimum printing density.

An analog video signal from a television (abbreviated as TV) receiver 18 is given to an analog signal processing circuit 19, and further given to an analog/digital converter 20 to be converted into a digital video signal, and sent to a data selector 7 via a line 21a. given to. When the data selector 7 switches and connects the lines 21 and 8, a video signal from the television receiver 18 is thermally printed on the thermal head 10. External device 1 and television receiver 18
Transfer time T1 of one line of video signal from 1 line to the shift register 23 which is a memory in the thermal head 10
1 is short and therefore less than the necessary energization time W11, the transfer of the video signal for the next line is temporarily interrupted, and the next 1 line is restarted after the predetermined minimum pause time W12 necessary to prevent heat accumulation has elapsed. Transfer video signals for lines.

P! thermally printed by the resistance heating elements R1 to Rm of the thermal head 10! = The recording paper may be thermal paper, which has the property of changing color depending on the temperature, or alternatively, instead of thermal paper, so-called plain paper may be used, and the ink sheet may ripen. It may be configured to be heated by the resistors R1 to Rm and thermally printed.

When performing thermal printing with multiple gradations, the data of each gradation segment of one line of video signal is given to the shift register 23, and the transfer operation to the shift register 23 is performed repeatedly for the number of gradations. r5T11 at the time of transfer.
may be detected and the energization time Wll may be automatically set.

Effects of the Invention As described above, according to the present invention, at least one line of video signals from a video signal generation source is transferred to a memory, and one line of heating resistors is activated based on the contents stored in this memory. It is possible to energize power all at once and heat it, and to set the energization time for one line by varying it.As a result, when the transfer time is long, the energization time of the heating resistor is set longer, and the transfer time is increased. When the transfer time is short, the energization time is set short, thereby preventing changes in density due to heat accumulation in the thermal head, making it possible to obtain the optimum print density regardless of the length of the transfer time.

[Brief explanation of drawings]

112I is a block diagram of an embodiment of the present invention, FIG. 2 is a waveform diagram for explaining the operation of the embodiment shown in FIG. A graph showing the relationship between the energizing time Wll and FIG. 4 is a diagram for explaining the transfer time T1 and the energizing time Wl,
FIG. 5 is a graph showing the thermal characteristics of the thermal head.

Claims (1)

[Scope of Claims] A thermal head having a plurality of heating resistors as one line; a video signal generation source that generates a video signal to be printed; and at least one video signal transmitted from the video signal generation source.
a memory for storing a line, a means for simultaneously energizing one line's worth of heating resistors in connection with the transfer operation based on the stored contents of the memory, and a time for energizing one line by the power energizing means. 1. A thermal printing device comprising: means for variably setting the image.