JPH04227193A - Video signal superposing and extending circuit - Google Patents

Abstract

PURPOSE: To expand the frequency band of recorded and reproduced video signals to a band width limited to a recording medium for preventing the loss of high-frequency luminance signals at the time of interchanging a VCR with a VCR of a standard VHS system. CONSTITUTION: In a video recorder, a video signal superimposing circuit is incorporated with an A/D converter 10 which generates digital video signals, a low-pass filter 40 which detects the video signals, a frequency superimposing section 30 which superimposes the video signals upon each other, and an adder 50 and expands the frequency band of the video signals so as to improve the resolution. A video signal spreading circuit is incorporated with an A/D converter, a basic band processing section 141 which removes high-frequency components, a frequency spreading section 150 which spreads superimposed video signal to their original band, and an adder 160. Therefore, the resolution can be maintained constantly even when a VCR is interchanged with a VCR of a standard VHS system.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a video recording and reproducing device that uses frequency superimposition technology to record many video signals, and in particular, the bandwidth of the basic video signal, which is limited by frequency superposition, can be reduced by the limitations of the recording medium. This invention relates to a frequency superposition and broadening circuit for extending the bandwidth to a wide range of frequencies.

0002

2. Description of the Related Art In recent years, consumer VCRs record video signals onto video cassette tapes using one of various methods. The well-known VHS system produces degraded screens primarily due to insufficient horizontal resolution.

Generally, an improved VHS system called Super VHS (S-VHS) achieves improved video image quality by recording full-band video signals on a video cassette tape and outputting improved video image quality. Occur. Such systems require good quality tape in cassettes and good quality recording and playback equipment.

However, the S-VHS system is a standard VHS system.
It is not reverse compatible with other VCRs. S-VHS type VC
The R can play both S-VHS and cassettes recorded on standard VHS VCRs;
R was unable to play back cassettes recorded on an S-VHS VCR. In addition, video signals with a wider bandwidth than that recorded by a standard VHS VCR can be recorded on a standard quality cassette, and S-VH
Standard VHS system VCR, which is a problem with S system VCR
The applicant has proposed an improved video recording and playback device that maintains compatibility with the
It is disclosed in US Patent Application No. 07-569029, filed on August 17, 1990. According to this US Patent Application No. 07-569029, after attenuating the high frequency component of the luminance signal during recording, the attenuated high frequency component is sub-Nyquist sampled to be superimposed on the low frequency component, and then the superimposed high frequency component is superimposed on the low frequency component. filters the signal. In this way, all the information present in the entire bandwidth of the luminance signal is included in the superimposed luminance signal, which has a bandwidth of about 2.5 MHz. During reproduction, the reproduced luminance signal is It is filtered with a low pass filter having a cut-off frequency of about 2.5 MHz, and the filtered luminance signal is spread out so that it is distributed over the original frequency band. After all, the above-mentioned US Application No. 07-569029 processes luminance signals within 2.5 MHz during recording and reproduction.

[0005]

[Problem to be Solved by the Invention] However, the standard VHS system VCR has approximately 3MHz on the video tape cassette.
It is possible to record and play back luminance signals within By the way, the videotape cassette recorded by the VCR described in the above-mentioned U.S. Application No. 07-569029 can be used as a standard VCR.
2.5 MHz when playing with HS system VCR
No. 07-569, which describes a videotape cassette recorded by a standard VHS VCR, in which video information distributed over the above frequency bands is lost.
Even when playing with a VCR described in No. 029,
Video information distributed in frequency bands above 2.5 MHz is lost.

[0006] Therefore, an object of the present invention is to reduce the frequency band of video signals recorded and played back to a band width limited to the recording medium in order to prevent loss of high-frequency luminance signals when compatible with a standard VHS system VCR. It is an object of the present invention to provide a video signal superimposition and expansion circuit that can be extended to

[0007]

Means for Solving the Problems In order to achieve the above-mentioned object, the video signal superimposition circuit of the present invention converts a full bandwidth video signal into a multi-bit digital video signal.
a converter, a brightness signal separation unit that separates a full-band brightness signal from the digital video signal, and a brightness signal separation unit that superimposes the full-band brightness signal, medium-high frequency brightness signal, on a limited low-frequency brightness signal to generate a limited band. a frequency superimposing unit for generating a superimposed luminance signal having a width, an adder for adding the superimposed luminance signal of the limited bandwidth and the luminance signal of the full bandwidth; a DA converter for converting a luminance signal into an analog form; a luminance signal recorder for modulating the output of the DA converter so that it can be recorded on a recording medium; and a recording element for recording thereon.

Further, the video signal spreading circuit of the present invention for achieving the above-mentioned object includes a reading element for reading information recorded on a recording medium, and demodulating the information read by the reading element to determine the luminance. a luminance signal regenerator for reproducing a signal; an A-D converter for converting the reproduced luminance signal into a digital luminance signal; and a high-frequency luminance signal superimposed on a limited low-frequency luminance signal in the digital luminance signal. The present invention is characterized in that it includes a frequency broadening section that widens the original occupied bandwidth, and an adder that adds the output of the frequency broadening section and the output of the A/D converter.

[0009]

[Operation] The present invention processes a luminance signal distributed in a limited bandwidth of a recording medium in a frequency superposition or frequency broadening path for processing a luminance signal distributed in a limited band, that is, in a first path. A second path, that is, a reference band processing section is added for recording and reproducing a luminance signal in a limited frequency band on the recording medium together with the superimposed luminance signal.

0010

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram of a video signal superimposition circuit according to an embodiment of the present invention.

In FIG. 1, the input terminal 5 is connected to a video signal source (
(not shown) and receives a composite video signal CV, and the input terminal 5 is connected to the input terminal of an AD converter 10. An output terminal of the A-D converter 10 is coupled to an input terminal of a luminance signal separation section 20 , an input terminal of a dynamic signal separation section 22 , and an input terminal of a chromaticity signal separation section 21 .

The output terminal of the luminance signal separation section 20 is coupled to the input terminal of the frequency superposition section 30 and the input terminal of the low-pass filter 40. The output terminal of the frequency superimposing section 30 and the output terminal of the low-pass filter 40 are correspondingly coupled to a first input terminal and a second input terminal of an adder 50, respectively. adder 50
The output terminal of is connected to the input terminal of the DA converter 11,
The output terminal of the DA converter 11 is connected to the input terminal of the luminance signal recorder 60. An output terminal of the luminance signal recorder 60 is coupled to a first input terminal of a chroma/luminance signal mixer 71. An output terminal of the chromaticity signal separator 21 is coupled to a first input terminal of the chromaticity/luminance signal mixer 70. An output terminal of the dynamic signal separator 22 is coupled to a control terminal of the luminance signal separator 20 and a second input terminal of the chromaticity/dynamic signal mixer 70 . The output terminal of the chromaticity/dynamic signal mixer 70 is D-A.
It is coupled to an input terminal of converter 12. The output terminal of the DA converter 12 is coupled to the input terminal of a standard color signal recorder 80. The output terminal of the standard chromaticity signal recorder 80 is connected to the second input terminal of the chromaticity/luminance signal mixer 71. The output terminal of the chromaticity/luminance signal mixer 71 is connected to a magnetic recording head 90.

FIG. 2 is an operational characteristic diagram of each part of the circuit shown in FIG. 1.

In FIG. 2, (A) is an output characteristic diagram of the luminance signal separation section 20, (B) is an operation characteristic diagram of the frequency superposition section 30 during frequency superposition, and (C) is an output characteristic diagram of the frequency superposition section 30. 3A and 3B are characteristic diagrams, in which (D) is an output characteristic diagram of the low-pass filter 40, and (E) is an output characteristic diagram of the adder 50.

The operation of the circuit shown in FIG. 1 will be explained with reference to the characteristic diagram shown in FIG.

The A/D converter 10 samples the composite video signal CV using a sampling clock of about 10 MHz, encodes the sampled signal, and generates a digital composite video signal DCV. The moving signal separator 22 separates a moving signal M representing the amount of movement of pixels in the screen from the digital composite video signal DCV.

The luminance signal separation unit 20 separates a spatially derived luminance signal and a temporally derived luminance signal from the digital composite video signal DCV, and combines these two luminance signals appropriately according to the value of the moving signal. A luminance signal L is generated. At this time, the luminance signal L has a bandwidth as shown in FIG. 2(A).

The chromaticity signal separation section 21 separates the chromaticity signal C from the digital composite video signal DCV.

After attenuating the high frequency component (luminance signal of 2.5 MHz or higher) of the luminance signal L, the frequency superimposing section 30
Figure 2 shows the high-frequency luminance signal after sub-Nyquist sampling.
superimposed on the low frequency luminance signal as shown in (B) of
The superimposed luminance signal is low-pass filtered to have a high-frequency cutoff characteristic of 2.5 MHz to generate a superimposed luminance signal L* as shown in FIG. 2C. The low-pass filter 40 removes high-frequency luminance components of 3 MHz or higher from the luminance signal L to obtain a basic band luminance signal BL distributed over the video cassette tape's limited bandwidth of 3 MHz, as shown in FIG. 2(D). Occur. The adder 50 adds the superimposed luminance signal L* distributed in a limited band and the basic band luminance signal BL to generate a luminance signal (BL+L*) as shown in FIG. 2(E). The DA converter 11 converts the digital luminance signal (BL+L) added by the adder 50 into analog form. The luminance signal recording unit 60 frequency modulates the analog luminance signal (BL+L*) generated by the DA converter 11 so that it can be recorded on a recording medium. The color/motion signal mixer 70 mixes the motion signal and the chromaticity signal (C+M) and sends it to the D-A converter 1.
Supply to 2. DA converter 12 converts the chromaticity signal C+M in digital form to analog form. The standard chromaticity signal recording unit 80 amplitude-modulates the mixed chromaticity signal C+M inputted from the DA converter 12 using a carrier wave of about 629 kHz. The chromaticity/luminance signal mixer 71 mixes the frequency-modulated luminance signal and the amplitude-modulated chromaticity signal and supplies the mixed signal to the magnetic recording head 90 . A magnetic recording head 90 records the output of the chroma/luminance signal mixer 71 onto a videotape cassette.

FIG. 3 is a block diagram of another embodiment of the video signal spreading circuit according to the present invention.

In FIG. 3, magnetic read head 100 is coupled to the input terminal of chroma/luminance signal separator 110. In FIG. A first output terminal of the chromaticity/luminance signal separator 110 is coupled to an input terminal of the luminance signal reproducing section 120, and a second output terminal of the chromaticity/luminance signal separator 110 is coupled to the standard chromaticity signal reproducing section 17.
0 input terminal. Luminance signal reproducing section 120
The output terminal of is connected to the input terminal of the AD converter 130. The output terminal of the A-D converter 130 is connected to the low-pass filter 1.
40 and an input terminal of the basic band processing section 141. The output terminal of the low pass filter 140 is coupled to the input terminal of the frequency broadening section 150. An output terminal of frequency spreader 150 is coupled to a first input terminal of adder 160 . An output terminal of the basic band processing section 141 is coupled to a second input terminal of the adder 160. Adder 16
The output terminal of 0 is coupled to the input terminal of DA converter 132. An output terminal of the DA converter 132 is coupled to a first input terminal of the composite video signal generator 180. An output terminal of the chromaticity signal reproducing section 170 is coupled to an input terminal of the A/D converter 131. The output terminal of the A-D converter 131 is connected to the input terminal of the chromaticity/dynamic signal separator 111. The first output terminal of the chromaticity/dynamic signal separator 111 is D-
It is coupled to the input terminal of A converter 133. and,
A second output terminal of the chromaticity/dynamic signal separator 111 is connected to a control terminal of the frequency broadening section 150. D-A converter 1
The output terminal 33 is coupled to a second input terminal of the composite video signal generator 180.

FIG. 4 is an output characteristic diagram for each part in the circuit shown in FIG. 3.

In FIG. 4, (A) of FIG.
FIG. 4B is an output characteristic diagram of the luminance signal reproducing unit 120 when playing back a video cassette tape recorded by the VCR of the present invention. Signal reproducing section 12
0 is an output characteristic diagram. And (C) in FIG. 4 is the standard V
FIG. 4D is an output characteristic diagram of the low-pass filter 140 when playing back a video cassette tape recorded by the HS system VCR, and (D) in FIG. 3 is an output characteristic diagram of the low-pass filter 140. FIG. (E) in FIG. 4 shows the basic band processing section 14.
FIG. 1 is an output characteristic diagram of No. 1. (F) in FIG. 4 is an output characteristic diagram of the frequency widening section 150 when playing back a video cassette tape recorded by a standard VHS system VCR.
(G) is an output characteristic diagram of the frequency broadening section 150 when playing back a video cassette tape recorded by the VCR of the present invention.

The operation of the circuit shown in FIG. 3 will be explained in detail in conjunction with the output characteristic diagram shown in FIG.

The magnetic reproducing head 100 reads information recorded on the video cassette tape and supplies it to the chromaticity/luminance signal separator 110.

The chromaticity/luminance signal separator 110 separates the information supplied from the magnetic reproducing head 110 into a frequency-modulated luminance signal and an amplitude-modulated chrominance signal.

The luminance signal regenerator 120 frequency-demodulates the frequency-modulated luminance signal separated by the chromaticity/luminance signal separator 110 to generate a luminance signal. Luminance signal regenerator 12
If the video cassette tape being played is a video cassette tape on which video signals have been recorded by a standard VHS VCR, the brightness signal generated at 0 will have a frequency characteristic as shown in (A) in Figure 4; If the video cassette tape inside is a video cassette tape on which a video signal has been recorded by the VCR of the present invention, it will have frequency characteristics as shown in FIG. 4(B).

The A/D converter 130 converts the demodulated luminance signal into a multi-bit digital video signal.

Low pass filter 140 filters the digital luminance signal to detect a luminance signal distributed within a limited bandwidth (within 2.5 MHz). When a luminance signal having a frequency characteristic as shown in FIG. 4(A) is input to the low-pass filter 140, the filtered luminance signal has a frequency characteristic as shown in FIG. When a luminance signal having a frequency characteristic as shown in FIG. 4B is input to the filter 140, the filter 140 has a frequency characteristic as shown in FIG. 4D.

The frequency broadening unit 150 widens the high-frequency luminance component superimposed in the filtered luminance signal having a limited bandwidth input from the low-pass filter 140 to the original frequency band, and then converts the chromaticity/dynamic component into the original frequency band. Depending on the magnitude of the dynamic signal applied from the signal separator 111, the low frequency luminance signal and the high frequency luminance signal are appropriately combined to generate a full bandwidth luminance signal. When a luminance signal outputted from the frequency widening section 150 has a frequency characteristic as shown in FIG. However, when a luminance signal having a frequency characteristic as shown in FIG. 4(D) is inputted to the frequency broadening unit 150, the luminance signal has a frequency characteristic as shown in FIG. 4(G).

The basic band processing unit 141 filters the digital luminance signal, detects the luminance signal distributed in a frequency band within 3 MHz, which is the limited bandwidth of the video cassette tape, and superimposes it on the detected luminance signal. By removing the high-frequency luminance signal, a luminance signal having frequency characteristics as shown in FIG. 4(E) is generated.

The adder 160 adds the luminance signal generated by the frequency widening section 150 and the luminance signal processed by the basic band processing section 141, and adds the luminance signal generated by the frequency widening section 150 to the luminance signal processed by the basic band processing section 141. is shown in Figure 4 (
When a video cassette tape recorded by the VCR of the present invention is played back, a brightness signal having a frequency characteristic as shown in (G) of FIG. 4 is generated. .

DA converter 132 converts the output of adder 160 to analog form.

The chromaticity signal regenerator 170 amplitude-demodulates the amplitude-modulated chromaticity signal to generate a chromaticity signal. The chromaticity signal contains a motion signal when a video cassette tape recorded by the VCR of the present invention is played back.

The A/D converter 131 converts the demodulated chromaticity signal into a digital chromaticity signal.

The chromaticity/dynamic signal separator 111 separates the digital chromaticity signal into a dynamic signal and a chromaticity signal, supplies the dynamic signal to the frequency broadening section 150, and supplies the chromaticity signal to the D-A converter 133. do.

DA converter 133 converts the digital chromaticity signal, which is the output of chromaticity/motion signal separator 111, into analog form.

The composite video signal generating section 180 attempts to combine the luminance signal output from the D-A converter 132 and the chromaticity signal output from the D-A converter 133 to form a standard composite video signal. It operates according to the following method.

[0040]

The present invention has the advantage that even when compatible with a standard VHS system VCR, the resolution can be maintained the same between the standard VHS system and the VCR.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of a video signal superimposition circuit according to the present invention.

FIG. 2 is an output characteristic diagram for each part of the circuit shown in FIG. 1;

FIG. 3 is a block diagram of another embodiment of a video signal spreading circuit according to the present invention.

FIG. 4 is an output characteristic diagram for each part of the circuit shown in FIG. 3;

[Explanation of symbols]

10, 130, 131 A-D converter 20 Luminance signal separation unit 21 Chromaticity signal separation unit 22 Dynamic signal separation unit 30 Frequency superimposition unit 40, 140 Low-pass filter 50, 160 Adder 60 Luminance signal recorder 70 Chromaticity /dynamic signal mixer 71 chromaticity/luminance signal recorder 80 standard chromaticity signal recorder 90 magnetic recording head 100 magnetic reproducing head 110 chromaticity/luminance signal separator 111 chromaticity/luminance signal separator 120 luminance signal regenerator 141 Basic band processing section 150 Frequency broadening section 170 Chromaticity signal regenerator 180 Composite video signal generation section

Claims (7)

[Claims] Claim 1: A video recording device that records a full-bandwidth video signal including a chromaticity signal and a luminance signal on a recording medium with a limited bandwidth, in which the full-bandwidth video signal is recorded as a multi-bit digital video signal. an A-D converter for converting the digital video signal into a luminance signal, a luminance signal separation section for separating a full-band luminance signal from the digital video signal, and a luminance signal separating unit for converting the full-band luminance signal into a limited low-frequency luminance signal. a frequency superimposition unit that generates a superimposed luminance signal having a limited bandwidth by superimposition; an adder that adds the superimposed luminance signal of the limited bandwidth and the luminance signal of the full bandwidth;
a D-A converter that converts the summed digital luminance signal into an analog format; a luminance signal recorder that modulates the summed luminance signal so that it can be recorded on a recording medium; and the luminance signal recorder. 1. A video signal superimposition circuit comprising a recording element that records the output of the above onto a recording medium. 2. A low voltage amplifier connected between the luminance signal separator and the adder that detects the luminance signal distributed in a band width limited to a recording medium among the luminance signals of all bands and supplies the detected luminance signal to the adder. 2. The video signal superimposition circuit according to claim 1, further comprising a bandpass filter. 3. A color signal separation section that separates a chromaticity signal from a digital video signal; a chromaticity signal recorder that converts the frequency of the chromaticity signal so that it can be recorded on a recording medium; further comprising a chromaticity/luminance signal mixer connected between the luminance signal recorder, the luminance signal recorder, and the recording element to mix the frequency-converted chromaticity signal and the modulated luminance signal and supply the mixture to the recording element. Claim 1 characterized by
The video signal superimposition circuit described in . 4. A motion signal separator for separating a motion signal from the digital video signal; a motion signal separator connected between the motion signal separator, the chromaticity signal separator, and the chromaticity signal recorder; 4. The video signal superimposition circuit according to claim 3, further comprising a chromaticity/dynamic signal mixer that mixes chromaticity signals and supplies the mixture to the chromaticity signal recorder. 5. The video signal superimposition circuit according to claim 4, wherein the recording element includes a magnetic head. 6. A video reproducing device for reproducing a full-band video signal consisting of a luminance signal and a chromaticity signal recorded on a recording medium with a limited bandwidth. a reading element for reading, a luminance signal regenerator for demodulating information read by the reading element and reproducing a luminance signal, and an A-D converter for converting the reproduced luminance signal into a digital luminance signal; a frequency broadening section that widens the high frequency luminance signal superimposed on the limited low frequency luminance signal in the digital luminance signal to the original occupied bandwidth; and adding the output of the frequency broadening section and the output of the A/D converter. A video signal spreading circuit characterized by including an adder. 7. Connected between the A/D converter and the adder, detecting a luminance signal distributed in a limited bandwidth of a recording medium during output of the A/D converter, further comprising a baseband processing unit that removes a high-frequency brightness signal superimposed on the limited low-frequency brightness signal among the brightness signals and supplies the brightness signal from which the high-frequency brightness signal has been removed to the adder. 7. The video signal spreading circuit according to claim 6.