JPS6127818B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording device that records a plurality of control signals on a control track (CTL track) of a videotape. The present invention relates to a magnetic recording and reproducing apparatus that records another control signal on the same CTL track without erasing the original CTL signal based on the reproduction pulse of the CTL track.

In conventional video tapes, the CTL track is used for circuit head or capstan control during playback, and only the positive pulses of the playback pulses are used. No other pulses are used. For this reason, a method has been proposed in which a negative pulse is reproduced in the interval between adjacent reproduction pulses for CTL signals, and this is used for purposes other than the above-mentioned control, for example, as a cue signal.

To explain this regarding a conventional video tape recorder, in FIG. Through recording amplifier 5
A control signal as shown in FIG. 2B is guided to the CTL track by the CTL head 6, and saturation recording is performed on the tape as shown as CTL signal 7 in FIG. As shown in FIG. 2B, the CTL signal 7 is a rectangular wave signal B that rises in synchronization with a synchronization signal (not shown) obtained by dividing the vertical synchronization signal of the video signal 4 in FIG. During reproduction, a positive pulse is reproduced corresponding to the rising edge of the rectangular wave signal B, as shown by C in the figure, and this is used for synchronous control of the rotary head or capstan. Here, due to the CTL signal rectangular wave 3, a first saturation magnetization pattern of N pole is produced on the video tape in the positive polarity part of the rectangular wave, and a saturation magnetization pattern of S pole in the negative polarity part of the rectangular wave.
The magnetization state as shown in the figure is recorded.

From the above explanation, only the positive pulse with period T of the reproduced signal C shown in FIG. 2C is used for controlling the rotary head or capstan, so the negative pulse shown in FIG. 2C can be used for other purposes. For example, by changing the duty of the rectangular wave signal B, the generation timing of the negative pulse of the reproduced signal C can be moved, that is, the time interval _T1 from the positive pulse to the negative pulse for the CTL signal can be set to various values. hand,
For example, this can include information as a queue signal. This allows the CTL track to also be used as a cue track without affecting the conventional CTL signal.

However, if such a CTL track is also used, the CTL signal is recorded in conjunction with the video signal of the video track, so it is difficult to delete only the cue signal after recording and try to record a new cue signal. For example, leave the CTL signal without erasing it,
Only the queue signal must be rewritten. However, until now there has been no device capable of such rewriting.

In view of this point, the present invention provides a device that can rewrite only the cue signal without affecting the recorded CTL signal in any way.

FIG. 3 is a block diagram of one embodiment of this invention, and FIG. 4 is a waveform diagram of each component.
A case is shown in which the CTL signal and the queue signal recorded at the time interval T ₁ are updated and recorded at the time interval T ₂ over two sections.

The present invention will be explained below based on the drawings.

In FIG. 3, a switch 8 connects the CTL head 6 and the amplifier 9 during normal playback, and is switched while receiving the cue signal recording command signal H. While connected to the amplifier 9, the signal reproduced by the CTL head 6 from the CTL track 3 is amplified by the amplifier 9 to obtain a reproduced signal A as shown in FIG. 4A. This reproduction signal A is applied to a negative polarity amplifier 10 and a positive polarity amplifier 11, and in the positive polarity amplifier 11, only the CTL signal is amplified to obtain a pulse output as shown in FIG. 4B. On the other hand, in the negative polarity amplifier 10, only the negative polarity signal is amplified to obtain a pulse output (not shown), which is used as a cue signal.

The pulse output of the positive polarity amplifier 11 is applied to a phase locked loop circuit (PLL) 18 consisting of a phase detector 12, a low pass filter 13 and a voltage controlled oscillator (VCO) 14.
This PLL 18 oscillates in synchronization with the regenerated CTL signal and generates the pulse C shown in Fig. 4C, but even if one or more of the regenerated CTL signals are missing on the way, the The time constant of the low-pass filter 13 is set sufficiently large so that the period does not change.

The output pulse C of the PLL 18 thus obtained is used for controlling the rotational speed of the rotating head or capstan, while the cue signal generating circuit 16
It is also added to the gate pulse generation circuit 17. During the two periods in which the queue signal generating circuit 16 receives the queue signal update recording command signal H, as shown in _FIG . next
Until the output pulse C of the PLL 18 arrives, a cue signal D that is a negative pulse is generated.

A detailed explanation of the cue signal update recording command H will be omitted here, but it is roughly as follows. In other words, Fig. 4 is generated in response to a recording command.
_{The signal H 0 shown} in _{FIG . A} recording command H is composed of _the pulse _{H 1 shown} in FIG. The configuration is such that H ₂ is applied to the queue signal generation circuit 16.

Further, when the gate pulse generating circuit 17 receives the above queue signal recording command, as shown in FIG. 4E,
A gate pulse E is generated which rises after a certain time delay from the output pulse C of the PLL 18 and falls a certain time before the next output pulse C. This type of gate pulse can be created by various methods, but for example, it can be created by combining two sets of one-shot multis. Here, it is assumed that the time width from the rising edge of the gate pulse E to the falling edge of the gate pulse E is set so as to cover all possible timing positions of the queue signal.

The queue signal D and gate pulse E generated as described above are applied to the next recording signal generation circuit 15, and as shown in FIG. do.

The recording queue signal F generated in this way is applied to the next switcher 8.
However, the switcher 8 is operating to connect the CTL head 6 and the recording signal generation circuit 15 by the queue signal update recording command signal, and during this time the connection between the CTL head 6 and the amplifier 9 is cut off. Further, even when the switch 8 is switched in this manner, the normal reproduction state is maintained. That is,
In the method of controlling the rotating head based on the CTL signal, the tape is run at a constant speed, and even if the switch 8 is switched, the control of the rotating head continues with the oscillation output of the PLL 18, which is synchronized with the CTL signal. There is also a method that uses CTL signals to control the capstan and run the tape at a constant speed.
As above, capstan control continues with PLL output. Therefore, the above recording queue signal F is
The CTL head 6 records it on the CTL track 3 as a new cue signal. Here, when a positive pulse among the pulses shown in FIG. 4F is applied to the CTL head 6, a current flows in a direction that results in saturated magnetization of the same polarity as the magnetization already saturated recorded in the CTL track 3 (in this example, N pole). flows to CTL head 6. Subsequently, when the negative pulse shown in the figure is applied, a current flows in the direction of saturation magnetization in the opposite direction (S pole in this example) to the CTL head 6, and disappears along with the gate pulse E, so a new saturation magnetization is generated by the recording cue signal F. is formed. Since the recording cue signal F is not applied to the CTL head 6 outside the gate pulse generation section,
The magnetization of CTL track 3 remains the same. Furthermore, since the direction of the current flowing through the CTL head 6 is determined as described above, the starting and ending ends of the magnetization of the newly recorded queue signal are continuously connected without changing the original magnetization and polarity. In this way
This means that the time interval between the CTL signal and the queue signal has been changed from T ₁ to T ₂ .

While a new queue signal is being recorded by the queue signal recording command, the CTL signal is not transmitted to the amplifier 9 as described above, and therefore the output of the positive polarity amplifier 11 is not applied to the PLL 18. Since the output pulse C continues to oscillate in almost the same state as it has been oscillating in synchronization with the reproduced CTL signal A until now, the original cue signal is
The CTL signal never disappears.

The CTL track recorded as above
When played back by the CTL head 6, a new cue signal is played back as shown in Figure 4G, and the original CTL head 6 is played back.
This means that the queue signal has been rewritten without affecting the signal in any way.

In the above embodiment, the positive pulse is the CTL signal,
The negative pulse was used as a cue signal, but the negative pulse
CTL signal, positive pulse can be used as cue signal,
In this case, the invention can be easily applied by simply reversing the polarity relationships such as positive, negative, N-pole, and S-pole in the above description.

The above explanation shows an example of updating and recording a queue signal on a CTL track in which a queue signal with a polarity opposite to that of the CTL signal is recorded. However, the present invention is not limited to this example. Needless to say, this method can be widely applied to updating either one of two types of signals recorded as magnetic recording.

Further, in the above embodiment, one second
Although an example has been shown in which a plurality of second signals are updated and recorded, the present invention can be similarly applied to a case where a plurality of second signals are updated and recorded.

It goes without saying that the switch 8 may be switched by the output of the gate pulse generation circuit 17 without depending on the cue signal update/record command H.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the recording pattern of a videotape, Figure 2 is a waveform diagram of the recording and playback signals,
FIG. 3 is a block diagram of one embodiment of this invention, and FIG.
The figure is a waveform diagram. In the figure, 3 is a control track, 6 is a head, 7 is a control signal, 8 is a switch, 9 is an amplifier, 10 is a negative polarity amplifier, 11 is a positive polarity amplifier, 12 is a phase detection circuit, 13 is a low-pass filter, and 14 is a Voltage controlled oscillator, 15 is a recording signal generation circuit, 16 is a cue signal generation circuit, 17
1 is a gate pulse generation circuit, and 18 is a phase locked loop circuit. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Scope of Claims] 1. In one recording track of a magnetic recording medium, polarity is changed such that a reversal portion to one magnetization polarity is a first signal, and a reversal portion to the other magnetization polarity is a second signal. A magnetic recording and reproducing apparatus configured to form different saturation magnetization portions and to reproduce and use the recorded signals includes: a head for recording or reproducing first and second signals on the recording track; A switcher that always takes out a playback signal from the head and applies a recording signal to the head while receiving an update recording command for the second signal, and a switch that synchronizes with the first signal taken out via this switcher. A phase locked loop circuit that outputs a pulse signal, and a second gate pulse that is delayed by a certain period of time based on the output pulse of this circuit and has a certain time width shorter than one cycle of the first signal. a gate pulse generating circuit that generates while receiving an update recording command of the signal, and generates a pulse signal having a polarity that has the same magnetization polarity as the first signal recorded on the recording track in synchronization with the gate pulse. death,
Next, a second signal generation circuit generates a pulse signal having a polarity opposite to the magnetization polarity at a time of a second signal for updating the update recording signal set within the period of the gate pulse. A magnetic recording and reproducing device equipped with. 2. The magnetic recording and reproducing device according to claim 1, wherein the magnetic recording medium is a video tape, the recording track is a control track, the first signal is a control signal, and the second signal is a queue signal. .