JPS60213185A - Aspect ratio converter - Google Patents

Abstract

PURPOSE:To transmit a signal having an aspect ratio different from that of a current television system in the band of the current system by inserting a signal component having frequency higher than that of a television signal having an aspect ratio different from that of the current system into the gap of these spectrum. CONSTITUTION:A luminance signal Y is separated into three frequency bands YL, YH1, YH2 through high pass filters 2, 3 and a low pass filter 1. The band YH1 is modulated at its amplitude by a carrier f1 through a modulator 4 and its lower bnad wave is extracted by a low pass filter 8 to shift the frequency. The signal Y is shifted to the position of the current system spectrum by inverting the phase of the carrier by a phase inversion circuit 7 in each line period and each field period. On the other hand, the YH2 is changed at its spectrum position by a modulator 5, a low pass filter 9 and a phase inversion circuit 7. Hue signals I, Q are limited at their bands by low pass filters 10, 11 and then rectangularly modulated by modulators 12, 13 and these modulated signals are added by an adder 15 to obtain a band signal based upon the current system.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a conversion device that converts the aspect ratio, that is, the aspect ratio of an image in a video signal. The present invention relates to a signal processing device suitable for transmitting and receiving video signals with different aspect ratios in the transmission band of the current television system.

[Background of the invention]

Current televisions use an aspect ratio of 4:3.

On the other hand, recently, high-definition television systems that transmit high-definition images have been developed. This system uses an aspect ratio of 5:3, and the horizontal direction of the image is 1.2 that of current TVs.
It is five times (5/4) longer.

Even if the number of scanning lines and frames are the same, in order to obtain the same horizontal resolution, a system with an aspect ratio of 5:3 requires 1.25 times the transmission bandwidth compared to a system with an aspect ratio of 4:3. become.

Therefore, in a system with an aspect ratio of 5:3, a problem arises in that the transmission band must be expanded.

[Purpose of the invention]

An object of the present invention is to provide a device that can transmit a video signal with an aspect ratio different from that of the current television system in the same transmission band as the current television system.

[Summary of the invention]

In the current television system (NTSC system), a luminance signal Y and a color signal I are transmitted within a band of 4.2 MHz.

Q is multiplexed. Figure 1 shows the frequency spectrum of this signal, and the spectrum of the television signal is (b), (
They are arranged discretely as shown in the enlarged view in C). Therefore, by using the hatched portions in the spectral gap (c) diagram, it becomes possible to transmit more information in the same transmission band as the current television system. That is, for a television signal with an aspect ratio different from that of the current system, transmission in the band of the current system becomes possible by packing high-frequency signal components into the gaps in these spectra.

Regarding the method of inserting high-frequency signal components into gaps in the spectrum of current television signals.

1 time-vertical" 1st on the two-dimensional frequency. Chapter 3 limit, or using a method such as stacking the color signal in the high range (for example, as described in IEICE Research Fund C383-61, July 1988, "Proposal for a high-definition TV system with complete communication"). ing).

[Embodiments of the invention] Hereinafter, the present invention will be explained in detail with reference to Examples.

FIG. 2 shows the distribution of frequency components of a television signal in order to explain the principle of inserting the high frequency component of the luminance signal of a television signal with an aspect ratio of 5:3 into the band of the current television system.

High frequency component Y of the luminance signal. , (4.2MHz~8.4M
Hz), and Ys2 (8,4MHz~10.4
MHz) components are each converted into a low frequency component signal by a frequency shift operation and multiplexed. The signal spectrum in this multiplexed case is shown in the enlarged diagrams in (b) and (C) of the same figure, where Y, , Y, and □ are inserted into the gaps between the conventional luminance signal and color signal spectra, respectively. There is.

The configuration of an embodiment of the conversion device of the present invention for realizing this is explained in Section 3. It is shown in Figure 4. FIG. 3 shows the configuration of the transmitting side, and FIG. 4 shows the configuration of the receiving side. First, FIG. 3 will be explained.

The luminance signal Y is converted to YL (0 to 4.2 MHz) by bypass filters 2 and 3 and a low-pass filter l.

YHI (4,2MHz-8,4MHz)l Yo 2
It is separated into three frequency bands: (8, 4 MHz - 10, 4 MHz). YH4 is carrier f+(f
1 = 4, 2 MHz), and the frequency shift is performed by extracting only the lower sideband wave with the low-pass filter 8. Note that by inverting the phase of the carrier for each line period and each field period using the phase inversion circuit 7, the signal spectrum can be placed at the position of the spectrum of YH1' shown in FIG. ■
), while Y)+2 is converted into a carrier fz (
fz = 8.4 MHz or 10.4 MHz), and the low-pass filter 9 removes the lower sideband wave to perform frequency shifting. In this case, the phase of carrier fz is
A phase inversion circuit 7 inverts the subcarrier f SC for each line period and frame period so that the phase is the same as that of the subcarrier f SC. Through this operation, the signal is converted into a signal with a spectrum like YH2' shown in FIG. 2(c) (hereinafter referred to as method-■).

On the other hand, the color signals I and Q are band-limited by low-pass filters 10 and 11, and then subjected to orthogonal modulation by modulators 12 and 13.

In this case, the carrier is f gc, and the phase is shifted by π/2 in the phase shift circuit 14 to realize orthogonal modulation.

These signals are added by an adder circuit 15 to obtain a signal with the same transmission band as the current television system.

FIG. 4 shows the configuration of the receiving side. In the separation circuit 16, YLI
Separate the YHI' r YH2'* and C component signals. YH1' is synchronously detected by the synchronous detection circuit 17, and the YH1 component is extracted by the bandpass filter 24. On the other hand, YH2' is subjected to synchronous detection by the synchronous detection circuit 19, and then the YH□ component is extracted by the bandpass filter 25. Note that the phase inversion circuit 18.degree. 20 switches the carrier phase so that it is the same as that during modulation.

On the other hand, regarding the color signal component, the synchronous detection circuits 21 and 22
After synchronously detecting the signals, the color signals 1. Extract Q.

The luminance signals YL, MHI', and YH2' are sent to the adder circuit 28.
, to obtain the original luminance signal Y.

FIG. 5 shows one sequence in the case where the high frequency components of the luminance signal and the two-color signal are inserted into the gaps in the current spectrum. In this case, the luminance signal YHt (4, 2
-6,2MHz), YH2(6,2MHz ~8.2
MHz) is O~2 depending on method -■ and method -■, respectively.
Perform a frequency shift to the MHz position.

On the other hand, as shown in (b), the color signals I and Q have their high frequency components QH and IN at f5-0.5MHz and fa, respectively.
= 0 to 0.5 MHz, O to 1.5 MHz by amplitude modulating with a carrier of 1.5 MHz and extracting the lower sideband.
Create a frequency shifted signal of Hz. By performing orthogonal modulation on these signals using carrier fsc and method -2, the signals are inserted into gaps in the spectrum of the color signal component band of 2 to 4.2 MHz. The configuration of the transmitting side and receiving side to realize this function is described in Section 3. Since it is obtained in the same manner as in FIG. 4, the explanation is omitted.

As described above in the embodiments, according to the present invention, it is possible to transmit and receive signals with different aspect ratios up to the Takaoka wave component with a simple configuration while maintaining the signal format of the current television standard.

Next, FIG. 6 shows the configuration of an image display device for displaying signals with different aspect ratios on a monitor. The demodulated signals Y, I, and Q are converted into signals with a desired aspect ratio by an aspect conversion circuit 29 and displayed on the monitor 30. Figure 7(a) shows a signal with an aspect ratio of 5:3 displayed on a monitor with an aspect ratio of 4:3, and Figure 7(b) shows a signal with an aspect ratio of 4:3 displayed on a monitor with an aspect ratio of 5:3. In (a) of the same figure, which shows an example of a waveform diagram of an image frame in a case where 80% of the demodulated signal including the central part is
The part shown in FIG.

Furthermore, if information that identifies the aspect ratio of the signal to be transmitted is inserted into the blanking period of the TV signal, the receiving side can use this identification information to perform aspect ratio conversion to match the aspect ratio of the monitor. Good images can always be obtained.

Further, in the above description, an aspect ratio of 5:3 was used as an example, but it is clear that similar effects can be obtained with other aspect ratios.

〔Effect of the invention〕

According to the present invention, it is possible to transmit a signal with an aspect ratio different from that of the current television standard in a signal band within the current television standard, and the effects obtained are extremely large.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the frequency spectrum of the current television system.
FIG. 2 is a frequency spectrum diagram of the present invention, FIGS. 3 and 4 are block diagrams of an embodiment of the transmitting side and an embodiment of the receiving side of the aspect ratio converter according to the present invention, respectively. The figure is a frequency characteristic diagram for explaining the operation of the embodiment of the present invention, FIG. 6 is a configuration diagram of an image display device implementing the present invention, and FIG. 7 is a waveform of an image frame for explaining the operation of the above-mentioned figure 6. It is a diagram. 1.8, 9, 10, 11, 26.27...Low pass filter, 2,3...Bypass filter, 24°25.
... Band pass filter, 4, 5, 12, 13 ... Modulator, 17, 19, 21, 22 ... Synchronous detection circuit, 6
, 7, 18, 20... phase inversion circuit. X i Figure (α) (C) 2nd day (C) Brother 3 mouths”/4 ’I34 mouths 5th day (0,)

Claims (1)

[Claims] 1. An aspect ratio conversion device that transmits and receives a television signal having an aspect ratio different from that of the current television system by inserting a high frequency component of the television signal having a different aspect ratio into a gap in the spectrum of the current television system.