JPH02119492A - Video recording and reproducing device - Google Patents

Abstract

PURPOSE:To add a pilot burst signal of the same frequency tuned to an input signal with a simple and inexpensive circuit by using a reproduced demodulation signal and a reproduced chrominance subcarrier reference signal so as to apply balance modulation and adding the resulting signal to a synchronizing signal portion of an input low frequency conversion color signal. CONSTITUTION:The reproduced low frequency conversion color signal is subject to balance modulation by using a signal demodulated into a chrominance subcarrier to generate a signal tuned in the same frequency as that of the signal inputted at low frequency conversion color signal dubbing and a changeover device 11 is provided, which adds the tuned signal to the input signal in the timing of a pilot burst signal with a timing pulse generated from a timing circuit 116. Thus, the addition and recording of a pilot burst signal tuned in the same frequency even at low frequency conversion color signal dubbing are realized with a simple and inexpensive circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a video recording and reproducing apparatus that is capable of adding a tuned pilot burst when dubbing a low frequency conversion color signal.

BACKGROUND OF THE INVENTION In recent years, video recording and playback devices, especially video tape recorders (
(VTR), emphasis is placed on high image quality.

Normal brightness as a dubbing method to improve image quality.

In contrast to a method of dubbing using a color composite signal, there is a method of separating a luminance signal and nine color signals and dubbing the color signal after low frequency conversion. This method is brightness.

This is an excellent dubbing method that causes very little deterioration in image quality because it allows dubbing while separating the color signals and eliminates circuitry.

In addition, in order to obtain stable high image quality, the input conditions during recording may be recorded on tape and used during playback.
It is known that a groove is added to the synchronization signal portion at the same frequency as the subcarrier of the color signal. For example, when the separation of the chrominance signal and luminance signal is incomplete, the phase of the pilot burst signal is advanced by 90' relative to the color subcarrier, whereas when the separation is perfect, the phase of the pilot burst signal is delayed by 90°. During playback, it is detected that the pilot burst has advanced by 90', which indicates that the separation of the luminance and 9 color signals is incomplete. A trap is placed in the vicinity of 1 MHz for the luminance signal, and is used for control to prevent an inversion phenomenon. However, the current VHS format does not have a method for adding a pilot burst signal, so it has not been possible to add a pilot burst signal and use it even when dubbing a low frequency conversion color signal.

A conventional video recording and reproducing device will be explained below. Third
The figure is a block diagram of a conventional video recording and reproducing device. 1 is a low-pass filter that extracts only the low-frequency conversion color signal, 2 is an addition circuit that adds the color signal and luminance signal, and 3 is a recordable device. 4 is a video head, and 6 is a luminance signal processing block.

The operation of the video recording and reproducing apparatus configured as described above is as follows.
The low-pass conversion color signal input from the UB color input terminal is input to a low-pass filter 1 that removes high-frequency components, while the luminance signal input from the DUB luminance input terminal is subjected to luminance signal processing and sent to a robust filter. This value is added to the output of R1, amplified by a recording amplifier to the optimum value for recording, and recorded on videotape.

Problems to be Solved by the Invention However, in the conventional configuration described above, there is no circuit for adding a pilot burst signal, and when a new pilot burst signal adding circuit is added, the frequency is the same as that of the input low-frequency conversion color signal. However, it has the disadvantage that a phase tuning circuit for tuning is additionally required, resulting in a large and expensive circuit.

was.

The present invention solves the above-mentioned conventional problems, and makes it possible to add a pilot burst signal tuned at the same frequency as the input signal using a simple and inexpensive circuit even when inputting a low-frequency conversion color signal dubbing. The purpose is to provide a recording/playback device.

Means for Solving the Problem In order to achieve this object, the video recording and reproducing apparatus of the present invention uses a reproduction demodulation signal for demodulating the reproduced low-pass converted color signal to a color subcarrier frequency and a reproduced color M1 carrier. A balanced modulation circuit that performs balanced modulation with a carrier reference signal, a timing circuit that creates a timing pulse in the synchronization signal portion, a switch that adds the output of the balanced modulation circuit to the input low-frequency conversion color signal at this timing, and its output. It has a recording amplifier that records the information on tape.

Effect: With this configuration, balanced modulation is performed using the reproduced demodulated signal and the reproduced color subcarrier reference signal, and this signal is added to the synchronization signal portion of the input low-frequency converted color signal, thereby performing low-frequency converted color signal dubbing. At the time of input, a pilot burst signal of the same frequency tuned to the input signal can be added using a simple and inexpensive circuit.

EXAMPLES Hereinafter, examples of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of a video recording and reproducing apparatus in an embodiment of the present invention.

In FIG. 1, 11 is a switch that adds a pilot burst signal, 12 is a low-pass filter that removes the high frequency range of the input signal, 13 is an addition circuit that adds luminance signals and color signals, 14 is a recording amplifier, and 15 is a A video head for recording signals, 16 a video head for playback, 17 a playback enhancer, 18 a low-pass filter for removing high frequencies of the playback signal,
19 is a luminance signal processing block, 110 is a synchronization separation circuit that separates a synchronization signal, 111 is a reference signal generator that creates a reference signal for a reproduced color subcarrier, 112 is a sub-balance modulation circuit that creates a reproduced demodulated signal, and 113 is a low frequency A balanced modulation circuit demodulates the converted color signal, 114 is a bandpass filter that extracts only the color subcarrier frequency, 115 is a balanced modulation circuit that generates a signal with the same frequency as the low frequency converted color signal, and 116 is a balanced modulation circuit that demodulates the converted color signal. 117 is a luminance signal processing block.

The operation of the video recording and reproducing apparatus configured as described above will be described below. FIG. 2 is a timing chart showing the timing of PL and B.

First, the low-frequency converted color signal 31 inputted from the DUB color input terminal is subjected to a switching device 11 to which a pilot Hurst signal is added, and a low-pass filter 12 to remove high-frequency components. The luminance signal input from the DUB luminance input terminal is processed by 117 luminance signal processing blocks, and 1
It is added with the output of low-pass filter 12 in adder 3,
The signal is amplified to the optimum value by 14 recording amplifiers and recorded by 15 heads. The other output system of the low-pass filter 12 is demodulated to the same frequency as the nine color subcarriers by a balanced modulation circuit 113, and then demodulated by a band-pass filter 114 to
Only the color subcarrier frequency is extracted and becomes the color signal output.

The input luminance signal is processed by a luminance signal processing block 19, and only a synchronization signal is extracted from the output signal by a synchronization separation circuit 110 and input to a sub-balanced modulation circuit 112. The other input of the sub-balanced modulation circuit 112 receives a reference signal of the reproduced color subcarrier frequency from the reference signal generator 111. The output of the sub-balanced modulation circuit 112 is input to a balanced modulation circuit 113 and a balanced modulation circuit 115 for pilot burst signals. A balanced modulation circuit 113 uses this signal to demodulate the color subcarrier. 11
The output of the reference signal generator 111 is input to the other input of 5, and the output 33 of 115 is input to the switch 11.

The output of the synchronization separation circuit 110 is used to generate a high lot burst signal timing 32 by a timing circuit 116 and is input to the switch 11. The output of the switch 11 is added with a pilot burst, passes through a low-pass filter 12, and becomes a signal 34.

Also, during playback, the signal played by the 16 heads is transferred to the 17
Amplified by a regenerative amplifier, 18 low-pass filters and 1
The signal is input to the luminance signal processing block No. 9.

As described above, according to this embodiment, the reproduced low-pass conversion color signal is balanced-modulated using the signal demodulated into the color subcarrier, and is tuned at the same frequency as the signal input when dubbing the low-pass conversion color signal. By providing a switch that generates a signal with the same frequency and adds this signal to the input signal at the timing of the pilot burst signal using a timing pulse, the pilot burst can be synchronized at the same frequency even when dubbing low-frequency conversion color signals. Adding and recording signals can be achieved with a simple and inexpensive circuit.

In the embodiment, 15 is a recording head and 16 is a reproducing head, but it is also possible to use the same head for both recording and reproducing purposes.

Effects of the Invention As described above, the present invention utilizes a signal that demodulates the reproduced low-frequency conversion color signal to a color subcarrier frequency, and balances the signal of the same frequency tuned to the input signal when dubbing the low-frequency conversion color signal. By using a modulation circuit to create the timing of the pilot burst signal from the synchronization signal using the timing circuit, and by providing a switch that adds the pilot burst signal to the input signal using that signal, even when dubbing low frequency conversion color signals, This makes it possible to realize an excellent video recording and reproducing device that can add pilot burst signals tuned at the same frequency using a simple and inexpensive circuit.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a video recording and reproducing device according to an embodiment of the present invention, FIG. 2 is a timing waveform diagram illustrating the operation of adding a high lot burst signal, and FIG. 3 is a block diagram of a conventional video recording and reproducing device. be. 11...off WPk, 12...low pass filter, 13...adder, 14...
Recording amplifier, 15... Recording head, 16...
...Playback head, 17...Playback amplification t? s, 1
s...Low pass filter, 19...Luminance signal processing block, 110...Sync separation circuit,
112...Sub-balanced modulation circuit, 113...
- Balanced modulation FILLE path, 114... Bandpass fill, 115... Balanced modulation circuit, 116
...Timing circuit, 117...Brightness signal processing block. Agent's name: Patent attorney Shigetaka Awano and 1 other person 411m after Figure 1. Antagonist

Claims (1)

[Claims] a balanced modulation circuit that performs balanced modulation of the reproduced low-pass conversion color signal with a reproduced demodulation signal that demodulates the reproduced low-frequency conversion color signal to a color subcarrier frequency and a reference signal of the reproduced color subcarrier; and a timing circuit that generates a timing pulse in a synchronization signal portion; A video recording and reproducing device characterized by comprising a switch that adds the output of the balanced modulation circuit to the input low-frequency conversion color signal at this timing, and a recording amplifier that records the output on a tape.