JPS59226579A - Printer of television receiver - Google Patents

Abstract

PURPOSE:To reduce the variation of copy density due to the temperature change of a thermal head itself and to enable copying of uniform density by detecting the temperature of thermal head and correcting electric conduction time table according to the detected temperature. CONSTITUTION:When copy command is given, a television signal (t) is written in an image memory 3. When one field is written, it is read out, a gradation density signal is converted to 15-bit density data by using a density data conversion table. On the other hand, the temperature of a thermal head in a heat sensitive printer 6 is detected by a temperature detecting circuit 12, and table value of density pattern of an electric conduction table is corrected. Accordingly, printing data (a) of pulse width corrected according to the temperature of thermal head is inputted to a head driving circuit 7. Thus, printing of density corresponding to the gradation density signal is made on the thermal paper.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a printer device for a television receiver.

Generally, when a cooking program is being broadcast on a television receiver, you may want to write down the menu list and ingredients displayed on the screen. This was extremely inconvenient as the person had to take notes on the menu list, ingredients, etc. while looking at the screen each time. In addition, if you record the cooking program mentioned above on a VTR and put it on, you can play it again, but even in that case, you have to search for the necessary screen and play it back statically, which is cumbersome. there were.

Therefore, the inventor of the present invention has already developed a very convenient printer device for a television receiver that can temporarily store the gradation density signal of the image on the television screen in RAM, read it out, and automatically make a hard copy. There is.

By the way, in this printer device, it is possible to copy the above-mentioned image by using a thermal printer widely used in facsimiles and the like and controlling the energization time of the thermal head in the printer. However, in this case, if the voltage is applied for the energization time set in advance according to the level of the gradation density signal, the copy density of the thermal paper will be affected by changes in the ambient temperature of the thermal head, especially when copying. If it continues for a long time, the temperature of the thermal head itself will rise due to self-heating, and therefore, even if the thermal head is energized for a constant time, the copy density will change significantly due to the temperature change of the thermal head itself, as shown in Figure 1. The problem is that you end up doing it.

The present invention has been made in view of the above problems, and provides a printer device for a television receiver that reduces variations in copy density due to temperature changes in the thermal head itself and makes copies with uniform density. It is intended to.

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

FIG. 2 shows a printer device for a television receiver according to an embodiment of the present invention. In the figure, 1 indicates a television signal t, a video signal V, a horizontal synchronizing signal S1, and a vertical synchronizing signal S.
2 is a synchronous separation circuit that performs synchronous separation; 2 is an A/D converter that converts the video signal V into a 4-bit gradation density signal d; 3 is a video memory that stores the gradation density signal d; 4 is a write command e
5 is a reference oscillator that generates a reference clock; 6 is a thermal printer having a thermal head; 7
is a head drive circuit that applies a constant voltage to the thermal head for a time corresponding to the pulse width of print data a.

Further, 8 is a CPU having a conversion table for converting the gradation density signal into print data a, and when a copy command C is input from the outside, the CPU 8 outputs a write command e to the write control circuit 4, and the CPU 8 outputs a write command e to the write control circuit 4, When this is completed, the video memory 3 is addressed and gradation density signals are successively output, and the signals are converted into print data a using the conversion table and output. Here, the conversion table consists of a density data conversion table and an energization time table, and the density data conversion table converts the gradation density signal into a number of consecutive "1's" corresponding to the gradation density, and the rest are "1"s. For example, for a signal with gradation density 5, the third
"111110ooooooooooo as shown in the figure"
In FIG. 3, the density i pattern (i=θ~14) is the data of the 1st+1st bit of the density data.On the other hand, the energization pattern shown in FIG. The time table is a numerical value x (0) to x (1
4).

Here, the transfer time T (1) of the density l pattern is the energization time T (0) to obtain printing with gradation density 1, the energization time to obtain printing with gradation density 2, and the energization time T (0) to obtain printing with gradation density 1. The difference between the energization time to obtain a print and the energization time to obtain a print (11) Similarly, the difference between the energization time to obtain a print with a gradation density of 15 and the energization time to obtain a print with a gradation density of 14 T (14) In this embodiment, the table value x of the energization time is
(1) is obtained as follows. In other words, when a CPU with an execution speed of 1.36 μsec is executed at 1/4 of that speed, the CPU is
After processing one table value, it takes 50 #s to be able to count the next table value.
Since approximately ec is required, the time T (1) for transferring one bit of the density data is T(1)=x(1)Xl, 36X4 +50 (us
). Therefore, when the temperature of the thermal head due to self-heating is 25°C, the data transfer time T (1) that can obtain the copy density of the number-mark paper corresponding to the gradation density signal is experimentally determined, and this transfer time T x (1) can be calculated from (1) and the above equation. It should be noted that the above table values may of course be determined depending on the CPU execution speed or table transfer speed if they differ.

In addition, in the figure, 9 is a counter, and 10 is 1.3 from CPU 8.
A frequency divider divides the oscillation signal of 6 μsec into 1/4, and 11 is a paper/rotation speed detection circuit that detects the presence or absence of thermal paper in the thermal printer 6 and the motor rotation speed, and the above CPυ8
further controls the generation of print data a and successive output of gradation density signals according to the motor rotation speed detected by the paper/rotation speed detection circuit 11, and also controls the output of an external warning device (Fig. (not shown) outputs a warning signal g. Also, 13 is a control signal line, 14 is an address bus,
15 is a data bus.

12 is a temperature detection circuit that detects the temperature of the thermal head, and the CPU 8 detects the temperature so that the copy density corresponding to the gradation density signal can actually be obtained regardless of changes in the temperature of the thermal head due to self-heating. The table value X(0) of the density 0 pattern of the energization time table is corrected in accordance with the detection signal of the circuit 12. Here, this temperature correction is the table value x when the temperature of the thermal head is 25℃
(0) as a reference, and uses the formula x(0) above 2°5 x (difference between actual head temperature and 25° C.). Note that the coefficient 2.5 in this equation was determined through experiments, and may of course be a different value depending on the temperature characteristics of the thermal head and thermal paper.

Next, the operation will be explained.

In this device, when a copy command C is given, the CPU
8 outputs a write command e to the write control circuit 4, then the television signal t is synchronously separated by the synchronous separator 1, and the video signal V is converted into a 4-bit gradation density signal d by the A/D converter 2. The signal d is then written into the video memory 3 according to the write control of the write control circuit 4.

And one field of video, that is, 280 pixels in the horizontal direction,
When all the gradation density signals d of 234 lines in the vertical direction are written into the video memory 3, the video memory 3 is transferred to the CPU 8.
The gradation density signal addressed by and read out is converted into 15-bit density data by the CPU 8 using a density data conversion table. On the other hand, the temperature detection circuit 12 detects the temperature of the thermal head inside the thermal printer 6,
The CPU 8 corrects the table value x(0) of the zero density pattern in the energization time table according to the temperature detected by the temperature detection circuit 12. First, the first bit of the density data (density 0 pattern) is transferred from the CPU 8 to the head drive circuit 7, and at the same time, in the CPU 8, the counter 9 counts the reference clock f from the frequency divider 10, and the count value When becomes the table value of the corrected density 0 pattern, the counting operation is stopped, and when the CPU 8 becomes ready to count the table value of the density 1 pattern of the energization time table, the transfer of the data of the first bit is completed. . From then on, each bit of data is transferred for a time determined by the table value. In this way, the first data "1" out of the number of "1" data corresponding to the gradation density is transferred for a time determined by the table value x(0) of the energization time table and the thermal head temperature,
And the remaining data "1" is transferred for only 1 time determined by the table value -x is input, and the circuit 7 applies a constant voltage to the thermal head for a time corresponding to the pulse width of the print data a, thereby applying PIil to the thermal paper.
Printing is performed with a density corresponding to the l density signal.

Further, FIG. 5 shows the experimental results of determining the change in copy density with respect to the temperature change of the thermal head without temperature correction and with temperature correction, and the solid line a+1 dotted line 5 in the figure shows the gradation density. 15 shows the relationship when there is no temperature correction and the solid line c and the one-dot dashed line d show the relationship when the gradation density is 1 and there is no temperature correction and when there is temperature correction.

According to FIG. 5, in the case of no temperature correction, as can be seen from the slopes of solid lines a and C, the copy density of gradation density 15 is more affected by the temperature change of the thermal head than that of gradation density l. ing. On the other hand, in the case of temperature correction, 1
The slope of the dashed dotted line d has become smaller, while the slope of the dashed dotted line d has become negative, but its absolute value has hardly changed. It can be seen that the values are small in both cases of 1.15, and there is almost no variation in copy density.

In the above embodiment, only the value of the density 0 pattern in the energization time table is temperature-corrected, but of course the present invention may also be configured to temperature-correct all the table values, and in that case, the copy density is even more It is possible to reduce the variation in

As described above, according to the printer device for a television receiver according to the present invention, the energization time of the thermal head is determined for the gradation density signal read from the video memory, and the density of the gradation density signal is actually obtained. Since the energization time is corrected in accordance with the temperature of the thermal head, it is possible to reduce variations in copy density due to temperature changes in the thermal head, and it is possible to effect uniform copying.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the relationship between temperature changes due to self-heating of the thermal head and copy density, Fig. 2 is a block diagram of a printer device for a television receiver according to an embodiment of the present invention, and Fig. 3 is a diagram showing the above-mentioned device. 7. Figure 4 is a diagram showing the values of the energization time table of the above device. Figure 5 is a diagram showing the change in copy density with respect to the temperature change of the thermal head with and without temperature correction. FIG. 3 is a diagram showing experimental results. 3... Video memory, 4... Write control circuit, 6...
・Thermal printer, 7...head drive circuit, 8...C
PU (drive control circuit), 12... temperature detection circuit (temperature detection means). Agent Masuo Oiwa

Claims (1)

[Claims] (11) A printer device that prints out images from a television receiver, which includes a video memory that stores gradation density signals of images to be printed out, and controls writing of the gradation density signals into the video memory. A writing control circuit, a thermal printer having a thermal head, a temperature detecting means for detecting the temperature of the thermal head, and a gradation density signal read from the video memory to determine the basic energization time of the thermal head and detect the gradation. a drive control circuit that corrects the basic energization time according to the detected temperature and determines the actual energization time so that the concentration of the concentration signal is actually obtained;
A printer device for a television receiver, comprising: a head drive circuit that applies a constant voltage to the thermal head during the actual energization time.