JPH0480592B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a scanning line conversion device used when, for example, a so-called high-definition television with 1125 scanning lines is received by an NTSC system device with 525 scanning lines. .

BACKGROUND TECHNOLOGY AND PROBLEMS So-called high-definition televisions have been proposed. This television has a large number of scanning lines, 1125, and an aspect ratio of 3:5, which is different from conventional systems such as NTSC. Therefore, in order to receive such television images, a new dedicated device is required.

However, it is expected that equipment for receiving such high-definition television will be extremely expensive. Therefore, it was considered to convert the scanning lines of high-definition television so that it could be received by devices using conventional systems such as NTSC. If you do this, the screen will not have high definition, but you will still be able to watch the program.

That is, for example, in high-definition television,
Of the 1125 scanning lines, the video signal is 1045 or
There are 1085 pieces. On the other hand, in the NTSC system, it is 480 out of 525. Therefore, by converting the number of scanning lines at the ratio of 480/1045 = 1/2.18, 480/1085 = 1/2.26, you can convert high-definition TV images.
It can be viewed on an NTSC system.

In that case, if a frame memory is used, the above-mentioned calculations of 1/2.18 and 1/2.26 are possible. However, high-speed frame memories for high-definition televisions are extremely expensive and are not suitable for television receivers used in ordinary homes.

OBJECTS OF THE INVENTION In view of these points, the present invention is intended to perform scanning line conversion with a simple configuration.

Summary of the Invention The present invention includes first to fourth line memories, and first to fourth level converters that convert signals to levels of 1/8, 7/8, 3/8, and 5/8, respectively. , an adder, and converts the number of scanning lines to 1/2.5. According to this scanning line conversion device, scanning line conversion can be performed with a simple configuration.

Embodiment In FIG. 1, a high-definition television signal from an antenna 1 is received by a tuner 2 and converted into a composite signal.

This signal is supplied to switches 3 and 4, the operation of which will be described later. Signals from the switches 3 and 4 are supplied to line memories 5, 6, 7 and 8, respectively.
The signals from these line memories 5 to 8 are 7/
8, 1/8, 3/8, 5/8 level converter 9, 10, 1
1 and 12. This level converter 9,1
The signal from level converter 11 and 12 is fed to adder 14. Signals from the adders 13 and 14 are supplied to a switch 15 whose operation will be described later. The signal from this switch 15 passes through an adder 16 to the receiver 1.
7.

Also, the signal from tuner 2 is sent to synchronous separation circuit 21.
and the synchronization signal is separated. This separated synchronization signal is supplied to the field discrimination circuit 22. This discrimination signal and synchronization signal are supplied to the switch control circuit 23.

Here, the control circuit 23 first sends the switch 3 in the period of the first scanning line 1o in the odd field.
is connected to the upper side, switch 4 is set to neutral, and the second
During the period of the scanning line 2o, the switch 3 is connected to the lower side and the switch 4 is set to the neutral position, and during the period of the third scanning line 3o, the switch 3 is set to the neutral position and the switch 4 is connected to the upper side, and the switch 3 is connected to the upper side during the period of the fourth scanning line 4o. Switch 3 is set to neutral and switch 4 is connected to the lower side, and a control signal is generated to set switches 3 and 4 to neutral during the period of the fifth scanning line 5o.This operation is performed every five scanning lines thereafter. repeated.

In the even field, the first scanning line 1
During the period e, switch 3 is connected to the lower side and switch 4 is set to neutral; during the period of second scanning line 2e, switch 3 is connected to the upper side and switch 4 is set to neutral;
Switches 3 and 4 are set to neutral during the period of the third scanning line 3e, switch 3 is set to neutral and switch 4 is connected to the lower side during the period of the fourth scanning line 4e, and switch 3 is set to the neutral position during the period of the fifth scanning line 5e. becomes neutral and switch 4
A control signal is formed in which the upper side is connected to the upper side, and this operation is repeated for every five scanning lines.

Furthermore, in the odd field, the second scanning line 2
After the end of the period of the fourth scanning line 4o, the memories 5 and 6 are read out, and the signals whose levels have been converted to 1/8 and 7/8, respectively, are added by the adder 13. are read out and the signals whose levels are converted to 3/8 and 5/8 are added by an adder 14,
This operation is repeated for every five scanning lines.

In the even field, the second scanning line 2
After the end of the period e, the memories 5 and 6 are read out, and the signals whose levels have been converted to 1/8 and 7/8, respectively, are added by the adder 13, and after the end of the period of the fifth scanning line 5e, the signals are read out from the memories 7 and 8. are read out and the signals whose levels are converted to 3/8 and 5/8 are added by an adder 14,
This operation is repeated for every five scanning lines.

Therefore, signals corresponding to the positions indicated by broken lines in FIG. 2 are formed and taken out from the adders 13 and 14. Note that 1:2 interlacing is maintained at these positions. Furthermore, since the signals are actually not formed until after the lower scanning line, they are respectively extracted at the positions indicated by the dashed-dotted lines after one scanning period, for example.

The switch 15 is then switched in accordance with the period during which this signal is extracted.

This reduces the number of scanning lines to 1/2.5. That is, 1085 lines become 434 lines, 1045 lines become 418 lines, and signals with 1:2 interlacing maintained are formed.

In addition, the horizontal period is approximately 30 μsec for high-definition television.
It is multiplied by 2.5 and becomes approximately 74μsec. On the other hand, in the NTSC system, it is approximately 63.5 μsec. Therefore, the position of the horizontal synchronization signal changes. Therefore, as shown in the figure, the separated synchronization signal is supplied to a synchronization signal forming circuit 24 to form a desired synchronization signal and added to the output signal by an adder 16. Note that this may be omitted if the memories 5 to 8 process the synchronization signal as well.

In addition, in the receiver 17, it is necessary to slightly widen the horizontal scanning oscillation tolerance so that the period of 74 μsec can be reduced, but conventional receivers generally have this tolerance range. Note that the scanning amplitude in the vertical direction is
Make it slightly narrower so that the scanning line density is equal.

Furthermore, the aspect ratio of a high-definition TV screen is 3:5.
This is different from 3:4 in the NTSC system. However, in the above example, the number of scan lines is e.g.
If there are 418 lines, the vertical length becomes 418/480 by making the scanning line density the same.
Therefore, 480/418 x 4/3 x 3/5 = 0.919, and approximately 92% of the video can be viewed.

This is how scanning line conversion is performed, and since this device uses a line memory and does not use an expensive frame memory, the entire device can be manufactured at an extremely low cost.

Also, since signals always pass through the same circuit in odd and even fields, the screen is extremely stable.

In other words, even with the same 1/2.5 conversion, for example, the first scanning line 1o is directly output in an odd field,
When the third and fourth scanning lines 3 ₀ and 4 o are added and extracted at a level of 1/2, 1:2
In order to interlace 1/4 of the first scan line 1e and 3/4 of the second scan line 2e in an even field,
are added and taken out, and 3/4 of the fourth scanning line 4e and the fifth
1/4 of scanning line 5e will be added and extracted,
The odd and even fields pass through different level converters. When the signals are passed through different circuits in this way, it is difficult to adjust the level, etc., and screen deterioration such as flicker is likely to occur.

Note that for the line memories 5 to 8, for example, a CCD can be used in the case of analog processing. In that case, write
Assuming that the number of pixels in one scanning line in the NTSC system is 480 x 4/3 = 640, the readout clock is 21.6MHz, which is 640 times the horizontal frequency of high-definition television (33.75kHz), and the readout clock is NTSC. Approximately 640 times the horizontal frequency 15.75kHz
Set to 10.08MHz. However, these calculations are based on the assumption that the entire area between the synchronization signals is 640 pixels, and in reality, it is performed for the effective screen and 92% of it, so the cost will be slightly higher.

In addition, for example, linear amplifiers can be used as the level converters 9 to 12 in the case of analog processing.

In addition, line memories 5 to 8 and level converters 9 to 1
The order of 2 may be reversed. Furthermore, adders 13 and 14
The order of the switches 15 and 15 may be reversed. In that case, two switches may be used to switch the outputs of the level converters 9 and 11, and 10 and 12, and one adder may be used to add the switch outputs.

Furthermore, the output of the tuner 2 may be AD converted and processed digitally. This circuit can also be incorporated into a part of a so-called digital television.

Further, this device can be applied to a device that displays an image by arranging a large number of display elements in a matrix, and when adjusting the number of scanning lines to match that of the display device.

Effects of the Invention According to the present invention, it has become possible to perform scanning line conversion with a simple configuration.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an example of the present invention, and FIG. 2 is a diagram for explaining the same. 3, 4, and 15 are switches, 5 to 8 are line memories, 9 to 12 are level converters, and 13 and 14 are adders.

Claims (1)

[Scope of Claims] 1. In a scanning line conversion method of converting the number of scanning lines of a high-definition television signal to 1/2.5 and converting it into a television signal of the NTSC system, in an odd field, the first of the high-definition television signals is , the second, third, and fourth scan lines as the first
~The output of the first line memory is supplied to the 4th line memory, ignoring the 5th scanning line, and the output of the 1st line memory is supplied to the 7/8 first level conversion circuit, and the output of the second line memory is The signals from the first and second level conversion circuits are added to form the first NTSC TV signal scanning line, and the signals are supplied to the third line memory. The output from the third and fourth level conversion circuits is supplied to the third level conversion circuit of 3/8, and the output of the fourth line memory is supplied to the fourth level conversion circuit of 5/8. The signals are added to form the second NTSC television signal scanning line, and in even fields, the first, second, fourth, and fifth scanning lines of the high-definition television signal are used as the first scanning line.
~The output of the first line memory is supplied to the fourth line memory, ignoring the third scanning line, and the output of the first line memory is supplied to the second level conversion circuit of 1/8, and the output of the second line memory is converted to 7/8.
The signals from the first and second level converting circuits are added to form the first NTSC television signal scanning line, and the third line memory outputs the signal. is supplied to the 5/8 fourth level conversion circuit, and the output of the fourth line memory is supplied to the 3/8 third level conversion circuit to convert the signals from these third and fourth level conversion circuits. A scanning line conversion method in which the scanning lines of the second NTSC television signal are obtained by adding the following, and these processes are repeatedly performed for every five scanning lines of the high-definition television signal.