JPH0134517B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for recording and reproducing video signals that can be used in video tape recorders and the like.

Conventional configurations and their problems In consumer color video tape recorders (VTRs) that are currently widely used,
The luminance signal occupies the recordable high band side.
The carrier color signal is converted into an FM signal, and the frequency of the carrier color signal is converted to the lower frequency side of the FM luminance signal, and a frequency multiplexed signal of these FM luminance signals and the lower frequency converted carrier color signal is recorded on a magnetic tape. . Then, during reproduction, the FM luminance signal and the low-frequency converted carrier color signal are separated from the reproduced multiplexed signal.
The original luminance signal is demodulated from the FM luminance signal, and the carrier color signal that has been low-band converted is frequency-converted to the original frequency band. In such a recording method, the color signal requires various complicated analog signal processing.

In addition, for ENG, which is developed for commercial use.
In a VTR, the luminance signal and chrominance signal are recorded using two tracks in separate heads, and the recording method for the chrominance signal is to record two chrominance signals.
There are two types: one that performs FM modulation and frequency multiplexing, and the other that compresses time, performs time division multiplexing, and then performs FM modulation. In either case, the processing during recording and reproduction of color signals is quite complicated.

In particular, as mentioned above, the color signal processing of a color VTR is quite complex, and this has been a problem in simplifying the VTR circuit. For example, in the above-mentioned consumer VTR, recording and reproducing methods using magnetic tape generate so-called jitter, which causes fluctuations in the relative speed between the magnetic tape and the magnetic head due to the expansion and contraction of the servo system and the magnetic tape. Therefore, in particular, the phase of the reproduced carrier color signal fluctuates, causing color unevenness. To prevent this, it is necessary to provide an automatic phase control circuit (APC) in the carrier color signal system on the reproduction side. This APC
The reality is that the circuit has a relatively complex configuration.
In addition, a guard bandless azimuth recording method is used to achieve high-density recording, but in this case, the phase of the carrier color signal is adjusted for each horizontal line in order to prevent crosstalk between adjacent tracks with respect to the color signal. The configuration is such that a 1H comb filter is placed on the playback output side. However, such processing not only complicates the circuit, but also requires a glass delay line to constitute the comb filter, which is a major impediment to miniaturization. Furthermore, when processing with analog circuits, there are quality problems such as variations in characteristics, making it difficult to obtain uniform performance, and characteristics deteriorating due to changes over time.

Purpose of the Invention The purpose of the present invention is to digitize the color signal processing circuit of a VTR, thereby making it possible to eliminate adjustment and use LSI, to reduce the size and cost of the circuit, and to improve performance uniformity and reliability. An object of the present invention is to provide a video signal recording and reproducing method that can obtain excellent quality.

Structure of the Invention The video signal recording and reproducing method of the present invention separates a color video signal into a luminance signal and a chromaticity signal, records both signals on a medium in an analog manner, and processes the luminance signal in an analog manner. The chromaticity signal is digitally processed, which means that the chromaticity signal processing circuit is completely digitalized, reducing the adjustment process in the production process and reducing the need for a single-chip IC for the chromaticity signal processing system. This makes it possible to do things like

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the basic structure of the present invention. In the figure, the color video signal applied to input terminal 1 is filtered through a low pass filter (LPF).
2. Supplied to band pass filter (BPF) 3,
The output of the low pass filter 2 is the luminance signal processing circuit 4
After that, the data is recorded on a recording/reproducing medium 8 such as a magnetic tape using a magnetic head or the like. The output of the bandpass filter 3 passes through an AD converter (A/D) 5, a color signal processing circuit 6, and a DA converter (D/A) 7, and is recorded on a recording/reproducing medium 8 using a magnetic head or the like.
A luminance signal extracted from the recording/reproducing medium 8 by a magnetic head or the like is supplied to a mixer (MIX) 13 via a luminance signal processing circuit 9. On the other hand, the color signal extracted from the recording/reproducing medium 8 is sent to the AD converter 10.
It reaches a mixer 13 via a color signal processing circuit 11 and a DA converter 12, and the output of the mixer 13 is supplied to an output terminal 14.

Next, the operation of the configuration example shown in FIG. 1 will be explained. A color video signal including a luminance signal and a color signal is applied to the input terminal 1. This color video signal is separated into a luminance signal and a color signal by a low-pass filter 2 and a band-pass filter 3. The luminance signal output from the low-pass filter 2 is subjected to processing such as frequency modulation in a luminance signal processing circuit 4 and recorded on a recording/reproducing medium 8 using a magnetic head or the like. Bandpass filter 3
The output color signal is converted into a digital signal by the AD converter 5. The AD converter 5 performs code modulation (PCM) on the analog signal and converts it into a pulse code string. It extracts the amplitude value of the signal at regular time intervals (sampling) and converts the signal into an integer value (quantizes it). ), which is expressed by a pulse code. The digitized color signal is processed by being applied to a color signal recording circuit 6 that executes necessary processing in the form of a digital signal on the recording side, and its output is returned to an analog signal by a DA converter 7. The DA converter 7 has the function of decoding the code from the given pulse string and converting it into an analog signal. In this case, the color signal processed as a digital signal is returned to an analog signal that is easy to record, and is transferred to the recording/reproducing medium 8. Record.

As is clear from the above description, the luminance signal and color signal are recorded on the recording/reproducing medium 8 in the form of analog signals.

Next, the playback side will be explained. Recording and playback medium 8
The luminance signal reproduced from the luminance signal is subjected to processing such as FM demodulation by the luminance signal processing circuit 9 and is then added to the mixer 13. On the other hand, the color signal reproduced from the recording/reproducing medium 8 is encoded into a digital signal by the AD converter 10, and the color signal processing circuit 11 performs necessary color signal processing on the reproduction side in the form of a digital signal. The processed digitized color signal is converted back to an analog signal by the DA converter 12 and applied to the mixer 13. Here, AD converter 1
0 and the DA converter 12 function similarly to the recording system AD converter 5 and DA converter 7.

The brightness signal and color signal reproduced from the recording/reproducing medium 8 are given to the mixer 13 as analog signals after undergoing necessary processing on the reproduction side, and the reproduced color video signal is output to the output terminal 14 of the mixer 13. Ru.

The embodiment shown in FIG. 1 is a method for recording and reproducing color video signals, in which color signal processing required on the recording side and color signal processing required on the reproducing side are processed using digital signals by color signal processing circuits 6 and 11. It shows that.

Generally, when processing color signals using analog signals, the circuit is complicated, but in this example, that part is digitally processed, so even complex processing can be easily integrated into LSI. The circuit can be made smaller and at lower cost. Furthermore, since color signals are also recorded in analog format on the recording/reproducing medium 8, the bandwidth required for recording remains the same as before. Furthermore, in order to digitize and process only the color signal, AD converters 5, 10 and
The scale of the DA converters 7, 12, etc. can be small compared to the case where the luminance signal is also digitized and processed. For example, when digitizing a luminance signal, a sampling frequency of 10.7 MHz, a coding bit count of 8 or more bits, and a bit rate of 80 Mbit or more are required, whereas when digitizing only a color signal, a sampling frequency of 2.5 MHz is required. MHz, about 6 bits is sufficient, and the bit rate may be about 15 Mbits. This difference greatly facilitates the design of LSIs and the like.

2 and 3 are main block configuration diagrams showing a specific embodiment of the present invention, and FIG. 2 shows a recording system,
Figure 3 shows the reproduction system. Various methods can be considered for recording color signals, but this example is for consumer use.
The case is shown in which it is applied to the low frequency conversion carrier color signal method that is most widely used in VTRs. In the low frequency conversion carrier color signal method, color signal processing in the recording system is relatively simple, and basically involves only frequency conversion. Therefore, since there is little merit in digitizing color signal processing, in this embodiment, color signal processing on the recording system is performed in analog, and only color signal processing on the reproduction side is performed digitally. The recording system will be explained with reference to FIG. A color video signal applied to an input terminal 1 is separated into a luminance signal by a low-pass filter 2, subjected to frequency modulation by an FM modulator 15, and then guided to a mixer 19. The carrier color signal separated by bandpass filter 3 has a carrier frequency of 3.58MHz,
Bandwidth is approximately ±500KHz. This is performed by the frequency converter 16 oscillator (OSC) 17 and low pass filter 18 on the lower side of the recordable band, e.g.
The frequency is converted into a band of 100 KHz to 1.1 MHz and added to the mixer 19. Therefore, the output of the mixer 19 is a frequency-multiplexed signal of the FM-modulated luminance signal and the low-frequency converted carrier color signal.
This is recorded on the magnetic tape 8a by the recording amplifier 20 and the magnetic head 21.

FIG. 3 is a block diagram of the main parts showing the reproduction system. The magnetic head 21 reproduces the signal recorded on the magnetic tape 8a, and the head amplifier 22 amplifies the signal to an appropriate amplitude. A high-pass filter 23 separates the FM-modulated luminance signal from the reproduced signal, and an FM demodulator 24 demodulates the reproduced signal into a luminance signal, which is then applied to the mixer 13. low pass filter 2
5 separates the low frequency conversion carrier color signal multiplexed in the low frequency range from the reproduced signal and guides it to the AD converter 26.
The AD converter 26 functions to digitize the low-pass conversion carrier color signal. That is 100KHz ~ 1.1MHz
The color signal distributed in the band is encoded with, for example, 6 bits at a sampling frequency of 2.5 MHz, and the digital signal is sent to the color signal processing circuit 27. The color signal processing circuit 27 performs necessary processing on the digitized color signal on the reproduction side, and in this embodiment, the color signal processing circuit 27 performs the processing necessary on the reproduction side. Processes such as correction, crosstalk removal for removing crosstalk from adjacent tracks on the magnetic tape, and frequency conversion for converting the low frequency converted color signal into the original carrier color signal are performed. The output of the color signal processing circuit 27 is returned to analog form by the DA converter 28 and is applied to the mixer 13. Here, the clock generator 29 generates clock pulses for digital processing of the AD converter 26, the color signal processing circuit 27, and the DA converter 28, and in addition to fixed clock pulses from a crystal oscillator, it It also has a clock pulse that follows the time axis fluctuations of the signal. The mixer 13 combines the demodulated luminance signal and the DA-converted chroma signal, and outputs the reproduced color video signal to the output terminal 14.

In the embodiments shown in FIGS. 2 and 3, in the low-pass conversion carrier color signal recording method, the color signal processing in the recording system where color signal processing is relatively simple is analog, and the color signal processing in the reproduction system where color signal processing is complicated. Digital processing has the advantage of reducing the circuit scale of the digital processing section and making the overall configuration more economical.

Although the above-described embodiment is limited to VTR processing, it goes without saying that this can be applied to any device that records or reproduces color video signals.

Effects of the Invention As is clear from the above description, the present invention separates a color video signal into a luminance signal and a chrominance signal when recording and reproducing a video signal, and records both signals in an analog manner on a recording medium. Since the processing format is analog processing for luminance signals and digital processing for color signals, all complex color signal processing can be performed with digital signals, which of course improves processing performance. about,
It can be easily integrated into an LSI, and as a result, compared to conventional color signal processing circuits, it is possible to reduce the number of parts and adjustment man-hours, resulting in an extremely economical effect.

Furthermore, by performing analog processing only on the recording system where color signal processing is relatively easy, the scale of the LSI can be reduced, and the color signal processing system can be made even more economically superior.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a main part according to an embodiment of the present invention, FIG. 2 is a block diagram of a main part of a recording system showing another embodiment of the invention, and FIG. 3 is a block diagram of a main part of a reproduction system thereof. FIG. 3 is a block configuration diagram. 2...Low pass filter, 3...Band pass filter, 4...Brightness signal processing circuit, 5, 10, 26...
AD converter, 6... Color signal processing circuit, 7, 1
2, 28...DA converter, 8...recording/reproducing medium,
8a... Magnetic tape, 9... Luminance signal processing circuit, 11
...color signal processing circuit, 13...mixer, 15...FM modulator, 16...frequency converter, 21...magnetic head,
24...FM demodulator, 27...color signal processing circuit, 29
...clock generator.

Claims (1)

[Scope of Claims] 1. A video tape recorder that separates a color video signal into a luminance signal and a chrominance signal, frequency modulates the luminance signal, converts the chrominance signal, frequency multiplexes both signals, and records analog signals on the same track, A video signal recording and reproducing method characterized in that the signal processing format is that the luminance signal is subjected to analog processing and the color signal is processed digitally. 2 Analog/digital converter and digital/digital converter are installed in the recording side signal processing system and the playback side signal processing system.
It has an analog converter and converts the input color signal and the reproduced color signal into digital signals,
2. The video signal recording and reproducing method according to claim 1, wherein the video signal is subjected to predetermined signal processing digitally, and then converted to an analog signal and outputted. 3 Color video signals are separated into luminance signals and color signals, and the recording format on the medium is analog recording for both luminance signals and color signals, and the color signal processing format is analog processing on the recording side and digital processing on the reproduction side. A video signal recording and reproducing method characterized by: