JPS59226574A - Printer for television signal - Google Patents

Abstract

PURPOSE:To drive a heat sensitive printer only by soft operation by dividing heating elements of a heat sensitive printer into plural groups and determining electric conduction time to each heating element by using a conversion table. CONSTITUTION:When a gradation density signal of one field is written in an image memory, a CPU14 converts the gradation density signal into density data of 15 bits by a density data conversion table. A group selection signal (b) is outputted from the CPU14 to a group decoder circuit 13, and switching elements 9 belonging to a group of heating elements are made on for maximum driving time. On the other hand, one of the number of data corresponding to the gradation density are transferred for each time on an energizing time table, and switching elements 8 are turned on by the pulse width time of corresponding segment selection signal (a), and heating elements belonging to the group 6 are electrically conducted. Similar operation is made for remaining groups 6.

Description

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

Generally, when a TV receiver is broadcasting a cooking program, for example, you may want to write down the menu list, monthly fee, etc. that appear on the screen. On machines, viewers had to look at the screen and take notes on the menu and ingredients each time, which was very inconvenient. In addition, if the above-mentioned cooking programs, etc. are recorded on a VTR, they can be played back again, but even in that case, it is necessary to search for the necessary screen and play it back statically, which is cumbersome. Ta.

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.

The inventor of the present invention conceived the idea of using a thermal printer, which has recently been widely used in facsimile machines, as the printer device, and developed the present invention. Moreover, in this case, each pixel of the hard copy of the TV screen is not simply black or white, but has a gradation density, so it is not possible to directly adopt the driving method of a thermal printer used in conventional facsimile machines. It overcomes the problem that it is not possible to use a heat sensitive drive, and uses a completely new and very simple driving method.

First, in explaining the present invention in detail, the present invention will be explained in detail.

As shown in Figure 1, there is a nearly linear relationship between the temperature of the thermal head in a thermal printer and the copy density of thermal paper within a certain range of head temperature. In other words, in order to copy the image that has been stored, it is sufficient to change the temperature of the thermal head according to the density of floor #N. There are two ways to change the temperature of the thermal head: one is to change the applied voltage to the thermal head itself, and the other is to keep the applied voltage constant and change the energization time of the thermal head, as shown in Figure 2.
When trying to drive and control a thermal printer using a microcomputer, the latter is more advantageous than the former in terms of material costs and the like. However, in the latter method, that is, when trying to produce gradation density by changing the energization time, since the gradation density signal in RAM is digital data, the gradation density signal can be directly sent to the thermal printer. It cannot be used as an energizing pulse.

Furthermore, due to its structure, thermal printers are able to copy all pixels of one scanning line of an image at the same time, but this method requires a large current to be passed through the thermal printer, making it difficult to maintain durability. It is undesirable.

In a fence printer device, the heating elements of the thermal printer are divided into a plurality of groups, the gradation density signals for all the heating elements of the group to be driven are read out from the video memory, and the successive gradation density signals are converted. The energization time for each heating element is determined using a table, and a voltage is applied for the energization time to perform divided printing for each group on each scanning line.

Next, one embodiment of the present invention will be described with reference to the drawings.

where ■ is a video signal, l is an A/D converter that converts the video signal V into a 4-bit gradation density signal d, and 2 is a floor tJ! 1li
A video memory 3 stores the signal d once, and a write control circuit 3 controls writing to the video memory 2 when a write command e is given. Further, 4 is a clock pulse generation circuit, Sl is a horizontal synchronizing signal, and S2 is a vertical synchronizing signal.

Further, 5 is a thermal printer that prints out images on thermal paper, and in the thermal printer 5, 14 heating elements 6 are arranged adjacent to each other, and each heating element is arranged adjacent to each other. 20 heating element groups consisting of 7,
8 connects one end of each heating element 7 taken out one by one in the scanning direction of the image, that is, in the right direction in the figure, from each heating element group 6, and connects each end of the heating element 7 between each connection point and the power supply. 1 switching element 9, 20 second switching elements 9 connected to the other end of the heating element 7 for each heating element group 6, and connected between each connection point and the ground; lO is a diode.

Further, 11 is a head drive circuit that drives the thermal printer 5, and in the head drive circuit 11, 12 latches the input 14 segment selection signals a, and selects a pulse width according to the pulse width of each segment selection signal a. A segment latch driver circuit 13 turns on each first switching element 8 for a certain amount of time, and a segment latch driver circuit 13 turns on a second switching element 9 belonging to the heat generating element group 6 to be driven in accordance with an input group selection signal. This is a group decoder circuit that is turned on for the maximum drive time allowed.

Furthermore, 14 is a CPU having a conversion table for converting the gradation density signal into the segment selection signal a;
Reference numeral 14 outputs a write command e to the write control circuit 3 when a copy command C is input from the outside, and when the writing is completed, addresses the video memo IJ 2 and all elements of the heating element group 6 to be driven. 7, and converts all the signals into a segment selection signal a using the conversion table, and converts the segment selection signal a and the group selection signal a for selecting the group 6 to be driven. occurs. 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 of gradation density 5, the 15-bit density data of "0" is "111110000000" as shown in FIG.
000'', and in this Figure 5, the density i pattern (i=0 to 14
) is data of the 1st+1st bit of the above density data.

On the other hand, the energization time table shown in FIG. 6 shows the time to continue transferring each bit of the density data (density i pattern), that is, the energization time T (0) to obtain printing with gradation density 1. Difference T between the energization time to obtain printing with gradation density 2 and the energization time to obtain printing with gradation density 1
(11. Similarly, there is a difference T (14) between the energization time to obtain printing with gradation density 15 and the energization time to obtain printing with gradation density 14. In addition, in the figure, 15 is a control signal 16 is an address signal line, and 17 is a data line.

Next, the operation will be explained.

In this device, when a copy command C is given, the CPU
A write command e is output from 14 to the write control circuit 3,
Then, the video signal V is converted into a 4-bit gradation density signal d by the A/D converter 1, and the signal d is written into the video memory 2 according to the write control of the write control circuit 3.

And one field of video, that is, 280 pixels in the horizontal direction,
When all 234 lines of gradation density signals d in the vertical direction are written into the video memory 2, the video memory 2 is then
The gradation density signal addressed by 4 and read out is converted to 15 by the CPU 14 according to the density data conversion table.
Converted to bit density data. Then, when density data is obtained for all 14 elements 7 of the heating element group 6 to be driven, the head drive circuit 11 outputs a group selection signal from the CPU 14 to the group decoder circuit 13, thereby selecting the heating elements to be driven. The second belonging to group 6
The switching element 9 is turned on for the maximum driving time. On the other hand, the segment latch/driver circuit 12 includes the CPU 1
4, the first bit data of each of the 14 density data (see the density 0 pattern in FIG. 5) is transferred for the transfer time T+01 of the density 0 pattern in FIG. 6, respectively.
Thereafter, data up to the 15th bit of each density data is sequentially transferred in the same manner. In this way, the number of "1" data corresponding to the gradation density is displayed at each time T (1
), the segment latch/driver circuit 12 receives 14 segment selection signals a having a pulse width corresponding to the level of the gray scale density signal read out, and the first switching element 8 selects the corresponding one. It is turned on for a time equal to the pulse width of the segment selection signal a, thereby energizing each of the 14 heating elements 7 belonging to the group 6, and 14 pixels having each gradation density are printed on the thermal paper. In addition, the remaining 19 heating element group 6
Printing is also performed in the same manner as above, and as a result, one scanning line of the image is copied.

In the apparatus of this embodiment as described above, it is possible to copy images on a television screen having gradation density by using a thermal printer, and since the thermal printer can be driven only by software operation, control is very simple. be. Furthermore, since the heating elements are divided into groups and copies are made for each group, the current required for the thermal head can be small, and the durability of the thermal head and, by extension, the printer can be guaranteed.

Note that the present invention is not limited to the above-mentioned embodiments (various modifications and changes are possible; for example, according to an image printer device, an image is hard-copied by a thermal printer; The heating elements in the group are divided into a plurality of groups, the gradation density signals for all the heating elements of the group to be driven are read out from the video memory, and the conversion table is used for the gradation density signal to convert the gradation density signals to each heating element. By determining the energization time and applying voltage to each heating element in the above group for the vj energization time, it is possible to make hard copies of gradation density images using a thermal printer using a completely new and extremely simple driving method. This has the effect of guaranteeing the durability of the printer.

[Brief explanation of the drawing]

1 and 2 are diagrams for explaining the present invention in detail, FIG. 3 is an embodiment of the present invention, FIG. 4 is a configuration diagram of the main parts of the above-mentioned device, and FIG. 5 is a diagram for explaining the above-mentioned device in detail. FIG. 6 is a diagram illustrating the values of the energization time table in the device. 2...Video memory, 5...Thermal printer, 6...
Heating element group, 7... Heating element, 8... First switching element, 9... Second switching element, 11...
Head drive circuit, 14...CPU (drive control circuit)
. Agent Masuo Oiwa Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] (1) A printer device that prints out images from a television receiver, comprising a plurality of heating elements arranged adjacent to each other and each consisting of an equal number of heating elements arranged adjacent to each other. a plurality of first switching elements, each of which has one end of the heating elements taken out one by one in the scanning direction of the image from each of the heating element groups and which is connected between each connection point and a power source; a thermal printer comprising a plurality of second switching elements whose other ends are connected to each heating element group and connected between each connection point and ground; a video memory that stores tone density signals of images to be printed out; It has a table that converts each level of the gradation density signal into the energization time of the heating element, reads out the gradation density signal for all the elements of the heating element group to be driven from the video memory, and then converts each heating element to each of the signals. a drive control circuit that determines the energization time of the heating elements; What is claimed is: 1. A printer device for a television signal, comprising: a head drive circuit that applies a power supply voltage by turning on the head drive circuit.