JPH0477379B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Technical Field> The present invention relates to a magnetic recording/reproducing device such as an 8 mm video tape recorder.

<Prior art> Generally, in an 8 mm video tape recorder, a magnetic tape is wound around a rotating drum in contact with each other over 180 degrees, and a video signal, a PCM signal obtained by pulse code modulating an audio signal, and a PCM signal on the magnetic tape are recorded. is recorded in the corresponding area. moreover,
An ID (identification) signal such as a cue signal is recorded in a specific portion of this PCM signal recording area. In such an 8mm video tape recorder,
When performing high-speed playback, the cue signal, etc.
It is necessary to reliably extract the ID signal.

However, in conventional 8mm video tape recorders, a phase shift may occur during high-speed playback, and as a result, the level of the playback output becomes low, making it impossible to extract the ID signal, making it difficult to cue. The problem is that it may not be possible.

<Object of the Invention> The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a magnetic recording/reproducing device that can reliably extract an ID signal during high-speed reproduction. The purpose is

<Structure of the Invention> In order to achieve the above-mentioned object, the present invention provides a magnetic recording and reproducing device for recording a video signal and a PCM signal in corresponding recording areas of a magnetic tape, and for reproducing both the signals. ID in the PCM signal recording area during high-speed playback.
A sampling signal forming circuit that forms and outputs a sampling signal in accordance with the timing of reproducing the signal recording portion, and a sampling signal forming circuit that forms and outputs a sampling signal in accordance with the timing of reproducing the signal recording portion, and 2 beat signal generating means for generating two beat signals; and a sample hold circuit for sample-holding the beat signal from the beat signal generating means in response to the sampling signal; The phase of the magnetic tape running is controlled based on the beat signal sampled by the magnetic tape, thereby maximizing the playback output when the ID signal is extracted.

<Examples> Examples of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of one embodiment of the present invention. In the figure, 1 and 2 are magnetic heads that rotate in contact with the magnetic tape T, 3 is a head amplifier that selectively switches and amplifies the output from the magnetic heads 1 and 2 in response to a head switching pulse, and 4 is an ID signal extraction circuit for extracting an ID signal. On the magnetic tape T, four pilot signals f1 to f4 having sequentially different frequencies are frequency-multiplexed recorded on each track along with a video signal and a PCM signal. The frequencies of the pilot signals f1, f2, f3, f4 are 6.5f ₀ ,
They are set to 7.5f ₀ , 10.5f ₀ , 9.5f ₀ (where f ₀ is the horizontal scanning frequency). These pilot signals
f1 to f4 are used for tracking control as is well known.

In the magnetic recording and reproducing apparatus of this embodiment, a sampling signal forming circuit 12 forms and outputs a sampling signal in accordance with the timing of reproducing an ID signal recorded in a specific part within a PCM signal recording area during high-speed reproduction. , a beat signal generating means 5 for generating two beat signals based on the reproduced outputs of the four pilot signals f1 to f4 recorded on the magnetic tape T; and this beat signal generating means 5.
A sample and hold circuit 13 that samples and holds the beat signal from the sample in response to the sampling signal.
It is equipped with

The beat signal generating means 5 generates a pilot signal f1.
Two beat signals are generated based on ~f4.
This beat signal is a beat signal between a pilot signal recorded on a certain recording track and each pilot signal recorded on recording tracks adjacent on both sides of this recording track, and has a frequency of, for example, 6.5. Assuming that a recording track on which a pilot signal f1 of f ₀ is recorded is being reproduced, pilot signals f2 and f4 with frequencies of 7.5f ₀ and 9.5f ₀ are recorded on adjacent recording tracks on both sides. Therefore, the frequency of the beat signal is f ₀ ,
3f becomes ₀ .

This beat signal generating means 5 is a head amplifier 3.
A low-pass filter 6 for extracting only pilot signals f1 to f4 from among the outputs from the
An extraction circuit 7 for extracting pilot signals f1 to f4 in the PCM signal recording area in response to a PCM area pulse, and a reference pilot signal and two pilot signals f1 to f4 from the extraction circuit 7 are mixed. The beat signal extraction circuit 8 extracts the beat signals f ₀ and 3f ₀ . The reference pilot signal applied to the beat signal extraction circuit 8 is a pilot signal having the same frequency as the pilot signal recorded on a predetermined recording track on which the magnetic head 1 or 2 is to run.

The two beat signals f ₀ and 3f ₀ from the beat signal generating means 8 are rectified by rectifying circuits 9 and 10, respectively, and are supplied to a mixer 11 for mixing, and then supplied to a sample and hold circuit 13. A sample-and-hold circuit 13 samples and holds the beat signal from the mixer 11 in response to the sampling signal, and provides the sample-and-hold signal as a phase control signal to a servo circuit (not shown).

As described above, the sampling signal forming circuit 12 forms and outputs a sampling signal corresponding to the timing of reproducing the ID signal recording portion in the PCM signal recording area of the magnetic tape T during high-speed reproduction.
This sampling signal is formed using head switching pulses.

Next, for convenience of explanation, the sampling signal from the sampling signal forming circuit 12 will be explained using the time chart for normal playback shown in FIG. Figure 2A shows the output waveform of the head amplifier 3 during normal playback, A1 is the PCM signal,
A2 each indicates a video signal. FIG. 2B shows a PCM area pulse for extracting a signal in the PCM area, and FIG. 2C is a waveform diagram showing an enlarged view of this PCM area pulse. Figure 2 D is
This shows a PCM signal corresponding to the PCM area pulse, and this PCM signal includes ID signals D1, D2,
Contains D3. FIG. 2E shows a sampling signal that corresponds to the timing of reproduction of a desired ID signal, for example ID signal D1 for cueing.

For convenience of explanation, the timing of the sampling signal from the sampling signal forming circuit 12 has been explained using a time chart for normal playback. This corresponds to the timing of playback of the portion of the signal recording area where the ID signal is recorded.

Next, the operation when high-speed reproduction is performed by the magnetic recording/reproducing apparatus of the present invention having the above configuration will be explained. For high-speed playback, press arrow 1 in Figure 3.
4, the magnetic head traverses the recording track 15 for reproduction, so the take-out circuit 7
The pilot signals f1 to f4 from the input terminal become signals with regular level changes as shown in FIG. 4B. Both beat signals from the beat signal extraction circuit 8 at this time are shown in FIGS. 4C and 4D, respectively. These beat signals are sampled and held in response to the sampling signal shown in FIG. 4E, and phase control is performed.

For example, when the playback phase advances and the beat signal moves to the left in the diagram relative to the sampling signal,
When the voltage of the beat signal in FIG. 4D becomes high and the phase is delayed, the beat signal moves to the right in the figure, and the voltage of the beat signal in FIG. 4C becomes high. Therefore, it is possible to perform phase control using the voltage sampled and held by the sample and hold circuit 13. Furthermore, since the sampling signal corresponds to the timing of reproducing the ID signal, that is, the timing of taking out the ID signal, FIG.
ID at maximum playback output level as shown in
A signal will be extracted, thereby
The ID signal can be reliably extracted during high-speed reproduction.

Note that FIG. 4A shows a PCM area pulse.

<Effects of the Invention> As described above, according to the present invention, a video signal and a PCM signal are respectively recorded in corresponding recording areas of a magnetic tape, and a magnetic recording and reproducing apparatus for reproducing both signals can be used at high speed. a sampling signal forming circuit that forms and outputs a sampling signal in accordance with the timing of playing back the ID signal recording portion in the PCM signal recording area during playback;
beat signal generating means for generating two beat signals based on the reproduced outputs of four pilot signals having sequentially different frequencies that are individually recorded on the magnetic tape; The present invention includes a sample hold circuit that samples and holds the sample in response to a sampling signal, and during high-speed playback, the phase of the magnetic tape running is controlled based on the beat signal sampled by the sample hold circuit. , the ID signal can be extracted when the reproduction output is at its maximum, making it possible to reliably extract the ID signal during high-speed reproduction.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, and FIG.
The figure is a time chart for normal reproduction, FIG. 3 is a schematic diagram showing the magnetization pattern of the magnetic tape, and FIG. 4 is a time chart for high-speed reproduction. 5... Beat signal generating means, 12... Sampling signal forming circuit, 13... Sample hold circuit.

Claims (1)

[Scope of Claims] 1. In a magnetic recording and reproducing apparatus for recording video signals and PCM signals in corresponding recording areas of a magnetic tape and reproducing both signals, the PCM signal recording area during high-speed reproduction is provided. a sampling signal forming circuit that forms and outputs a sampling signal in accordance with the timing of playing back the ID signal recording portion of the magnetic tape; and a sampling signal forming circuit that forms and outputs a sampling signal in accordance with the timing of playing back the ID signal recording portion of the magnetic tape, and a sampling signal forming circuit that reproduces and outputs four pilot signals having sequentially different frequencies that are individually recorded on the magnetic tape. beat signal generating means for generating two beat signals based on the beat signal; and a sample hold circuit for sample-holding the beat signal from the beat signal generating means in response to the sampling signal; 1. A magnetic recording and reproducing device characterized in that phase control of magnetic tape running is performed based on a beat signal sampled by a sample and hold circuit.