JPS59175018A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To ensure a normal detection of a pilot signal for tracking with no deterioration of a sound signal and to improve the automatic tracking reliability, by recording the sound signal to a track in the form of a composite signal together with a video signal, etc. CONSTITUTION:An attenuator 31 is provided at the input terminal of a video signal 22 to attenuate the signal 22 when a switch 24 is turned off and transmits it to a mixing circuit 23. The disturbance is avoided by dropping the video signal recorded in a record side channel down to a level where a head amplifier of the reproduction side is not saturated mainly with the crosstalk of a luminance signal in a reproduction detecting period of a recording pilot signal (f). This countermeasure is possible with use of a filter since the video signal has a different frequency band from the signal (f). Thus it is possible to detect the pilot signal in a normal way and therefore to improve greatly the automatic tracking reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording and reproducing apparatus using a rotating magnetic head, and more particularly to a magnetic recording and reproducing apparatus that detects the amount of track deviation using a pilot signal.

In order to cause a magnetic head to correctly trace a recording track on a recorded tape, a device has been developed in which a rotating magnetic head is movable in the width direction and automatically performs tracking. The tracking signal used in this type of device is a reproduction pilot signal F having a constant frequency in a frequency range lower than the low frequency conversion color signal for tracking during reproduction, as shown in Figure 1. , superimposed and recorded on the video signal for each recording track A,
In addition, for self-correction of the head position during recording, a recording pilot signal f is separately recorded in a part of each track, and immediately after the recording area of this recording pilot signal f, 1 to 2
It is configured by using the fish signal @ area S of H as the pilot signal readout area. By setting the pilot signal in this way, if there is a track misalignment during playback, two types of pilot signals are available: a pilot signal for playback of the track being played, and a pilot signal due to crosstalk from the adjacent track to which the head approaches. track deviation is detected from these, and during recording, the recording is temporarily stopped in the no-signal area S, and the recording pilot signal t of the adjacent track is reproduced and detected by entering the reproduction mode,
Auto-tracking is performed by detecting the relative position with respect to the adjacent track.

Figure 2 shows the VT for performing the above-mentioned tracking operation.
This is a block diagram showing the main parts of R. Rotary transformers 2a*2b are connected to magnetic heads la and 1b provided at 180" symmetrical positions on the rotating drum, and recording and reproducing of signals is executed. The luminance signal and chroma signal outputted from the signal circuit 3 are multiplexed with the pilot signals F and f given from the pylon 1-signal generation circuit 4 in the mixing circuit 5, and are input to the recording amplifier 6.The pilot signal generation circuit The pilot signals formed in 4 are a reproduction pilot signal t and a recording pilot signal F for tracking detection in reproduction and recording modes.
and is output to the mixing circuit for recording on each track as shown in FIG.

The output of the recording amplifier 6 is sent to the rotary transformers 2a, 2b or the head amplifier 7 via switches 8a, 8b that switch the magnetic heads 1a, 1b to playback or recording mode.
Connected to a*7b.

The outputs of the head amplifiers 7a and 7b are connected to an output terminal 10 via a channel selection switch 9 for video signals and pilot signals. The pilot signal multiplexed with the video signal by the mixing circuit 5 is sent to the recording amplifier 6, the switch (3a,
8b and rotary transformers 2a, 2b to the magnetic heads ia, lb, and recorded on the magnetic tape. During reproduction, both switches 8a and 8b are switched to the reproduction side, and the signals from the magnetic heads 1a and 1b are read out to the output terminal 1o via Herad amplifiers 7a and 7b.

In tracking using the pilot method as described above, in tracking in recording mode, the magnetic head is moved in a very short distance 1ffi (no signal area S in Figure 1) in order to reproduce and detect the pilot signal f of the previously recorded adjacent track. It becomes necessary to switch to playback mode and operate. During this period S, the video signal is interrupted, but such an interruption of the video is processed by dropping out during playback, and the recording location of the pilot signal for recording is usually set at the top or bottom edge, which does not cause problems on the playback screen. Therefore, the effect on the image in either case is negligible.

By the way, switching from the recording mode to the above-mentioned temporary reproduction mode is performed by simultaneously switching both switches 8a and 8b. This is done on the back head side that is not in contact with the magnetic tape (for example, 1
When b) is kept in the recording state, the recording signal voltage applied to the rotary transformer 2b is several volts, and the reproduction signal level generated at the head 1a on the side that detects the pilot signal is a minute signal level of 0.11V or less. However, in the rotary transformer normally used, due to crosstalk between both channels, the crosstalk leaking from the recording signal to the playback channel is much larger than the detection pilot signal, which is not the original purpose. Pilot signal detection becomes impossible.

Therefore, the switches 8a and 8b are normally operated in conjunction with each other.

In addition, in recent years, in order to improve the quality of recorded audio signals, a type of VTR that modulates the audio signal, multiplexes it with a video signal, etc., and records it on a video track with a rotating magnetic head.
is proposed. In such a VTR, a temporary signal dropout in the recording mode described above results in an interruption of the audio signal, and the fact that the audio signal interruption period extends to several hours is a problem that cannot be ignored in terms of sound quality.

Figure 3 shows a type of V that multiplexes and records the above-mentioned FM-modulated audio signal and video signal onto a video track.
It is a figure of the rotating drum part used for TR. In the figure, a magnetic tape 12 contacts a rotating drum 11 with magnetic heads 1a and 1b provided at symmetrical positions at an angle of 180 degrees or more to form a recording area. Of the recording areas, an area 13 extending 180 degrees from the start is a video area for recording and reproducing video signals and audio signals, and the other side of the recording area is a separate continuous PC for recording PCM audio signals, for example.
M area 14, and the recording pilot signal f is recorded in an overlap area 15 between the two areas. therefore,
While one magnetic head 1b is recording and reproducing in the PCM area 14, the other magnetic head 1a is recording and reproducing in the video area 13, and simultaneously records and reproduces signals of two channels.

FIG. 4 shows the recording state of signals in each track. In the area 16 of the track, the main signal is a mixture of a luminance FM modulated signal, a low frequency conversion chroma signal, an FM modulated audio signal, and a pilot signal for reproduction. In the video area 13, the two magnetic heads 1a and 1b are
It records and plays continuously by switching over each time. The signal in the track area 17 is mainly the PCM area 14 in FIG.
This is a PCM audio signal recorded in , on which a pilot signal F for reproduction is superimposed. The signal recorded subsequent to area 17 is a pilot signal f for recording, and its period TR is normally set to 1 to 2H.

As described above, the recording pilot signal f is transferred to the video area 13.
By providing it outside of the recording pilot signal f, the period T
The combined period (TR+TP) of t and the regeneration detection period Tp (usually about one day) of the same pilot, which is set as the no-signal area S, prevents direct interference with other signals and prevents signal loss. This eliminates the occurrence of However, even if you set the recording area as described above,
For example, when the magnetic head 1b records a recording pilot signal f and immediately attempts to reproduce and detect the same pilot signal f on an adjacent track, the other magnetic head 1a is recording the main signal 16, and the Due to crosstalk, it is actually impossible to detect the regeneration of the pilot signal f.

Figure 5 explains the relationship between the spectra of these signals.
f is the recording pilot signal (around 200KH2), 18 is the low frequency converted chroma signal (around 250KH2 to 1.25MHz), 19
is an FM modulated audio signal (1.3MHz to 1.6MHz)
M1-(about Z) and 20 are FM-modulated luminance signals.

As can be seen from the above-mentioned spectrum relationship diagram, there are two types of crosstalk interference in the recording current flowing through the magnetic head 1a. One is that because the reproduction pilot signal F and the low-frequency conversion chroma signal 18 closely overlap the spectrum of the recording pilot signal f, the recording pilot signal r cannot be properly detected due to crosstalk. The other reason is that the brightness signal 2o of the recording current is separated from the recording pilot signal f in terms of the band, so it can be removed by a filter, but because the level of crosstalk is high, the head amplifier 6 It becomes saturated and the playback operation becomes virtually impossible.

As mentioned above, in conventional devices, attempting to prevent crosstalk between channels may result in audio signal interruption,
Alternatively, due to the relationship between the spectra of each signal and crosstalk, it becomes difficult to detect the recording pilot signal f, making it impossible to obtain a proper tracking operation.

Therefore, the main object of the present invention is to provide a magnetic recording/reproducing apparatus which solves the above-mentioned problems and can perform the tracking operation normally without interrupting the audio signal.

The above objects and other objects and features of the invention will become more apparent from the following detailed description with reference to the drawings.

To summarize the invention, a pilot signal is recorded on a part of a track for automatic tracking during recording and reproduction in a magnetic recording/reproducing device, and this pilot signal is detected to magnetically control movement corresponding to track deviation. When one magnetic head is in a state where a pilot signal is being reproduced, the other magnetic head is still kept in a recording state, and at least an audio signal is supplied as a recording signal to this magnetic head. , and other signals are attenuated or blocked to prevent interruption of the audio signal, and the level of the recording signal is reduced to a negligible effect on the pilot signal playback operation, increasing the reliability of tracking. It is something that enhances.

FIG. 6 is a block diagram showing a recording and reproducing section according to an embodiment of the present invention. In the figure, parts equivalent to those in FIG. 2 are designated by the same reference numerals.

In this embodiment, the FM-modulated audio signal 21 is converted into a video signal (luminance signal, low frequency conversion chroma signal, and reproduced pilot signal @
) 22, and both signals 21 and 22 are combined in a mixing circuit 23, but the input side of the video signal 22 is connected to the input side of the video signal 22 in the recording mode as will be described later. A switch 24 is provided for turning off the reproduction period of the recorded pilot signal @f. V
A PCM audio signal 25 and a recording pilot signal f are input from the other signal input terminals of T and R, and are combined by a mixing circuit 26. Each mixing circuit 23.26
The two output signals synthesized by the signal distribution switch 27
．． 28 to the next-stage independent recording amplifiers 5a and 6b. The signal distribution switches 27 and 28 select the respective output signals of the mixing circuits 23 and 26 to the recording amplifiers 6a and 6b according to the recording areas 13, 14, and 15 in the positional relationship between the magnetic heads 1a+1b and the magnetic tape described above. This is a switch that supplies Recording amplifier 5a, 5
head amplifiers 7a and 7b are connected to the head amplifiers 7a and 7b via independent switches 8a and 8b, respectively. In addition, switch 8
a+8b serves to switch between connecting the rotary transformers 2a and 2b connected to the magnetic heads 1a and 1b to the recording amplifiers 5a and 5b or to the head amplifiers 7a and 7b; 8b independently turns on and off in synchronization with the rotation of the drum, as shown in the timing diagram of FIG. 7, which will be described later. The head amplifier 7
A switch 9 and a switch 29 are connected to the output ends of the terminals a and 7b, and the switches 9 and 29 are connected to each other to switch the connection terminals.
An output signal is derived at 0. By switching the switches 9 and 29, the main signal @16 including the video signal etc. is output to the output terminal 10, and the PCM audio signal 25 and the recording pilot signal @f are output to the output terminal 30.

Each switch included in the device operates in the recording mode in the switching timing relationship shown in FIG. 7.

The connection state of each switch shown in FIG. 6 shows the state when the magnetic head 1b is reproducing and detecting the recording pilot signal f in the recording mode. That is, the switch 8a connects the magnetic head 1a and the rotary transformer 2a to the recording amplifier 6a, and records the main signal 16 on the magnetic tape. Further, the switch 81) is the magnetic head 1b.

The rotary transformer 2b is connected to the head amplifier 7b, and a minute signal from the magnetic head 1b is passed therethrough.

When the recording pilot signal f is being recorded (timing T in FIG. 7), the switch 24 is turned on and the audio signal 21 and the video signal 22 that have passed through the switch 24 are mixed in the mixing circuit 23. Signal distribution switch 2
7, the signal is supplied to the recording amplifier 6a. The recording current output from the recording amplifier 6a is applied to the magnetic head 1a via the rotary transformer 2a by a switch 8a, thereby recording the main signal.

On the other hand, at this timing, the PCM audio signal 25 does not exist, and only the recording pilot signal is sent to the mixing circuit 26.
．． Signal distribution switch 28. Recording amplifier 6b, switch 8
magnetic head 1b along the path of b and rotary transformer 2b.
is supplied to the recording pilot signal f, and recording of the recording pilot signal f is executed. Immediately after this recording pilot message @f was recorded,
The mode is switched to the pilot signal regeneration detection mode (timing T2 in FIG. 7) for a short period of time. In this state,
The switch 8b is switched to the head amplifier 7b side to enter the playback state. At the same time, the switch 24 is also turned off, the video signal 24 that has been supplied to the magnetic head 1a is cut off, and only a relatively low level audio signal is recorded. Therefore, crosstalk from the recording side channel to the reproduction channel can be reduced to an allowable extent, and tracking by pilot signal detection can be performed normally.

FIG. 8 shows another embodiment of the present invention, and shows the seventh embodiment.
Compared to the embodiment shown in the figure, a switch 2 is installed at the input end of the video signal 22.
An attenuator 31 is added that attenuates the video signal 22 and transmits it to the mixing circuit 23 when the video signal 4 is turned off. In this embodiment, during the reproduction detection period of the recording pilot @f, the recording side channel lowers the level of the recorded Eirin signal to a level where the reproduction side head amplifier does not become saturated mainly due to the crosstalk of the luminance signal. This is to avoid interference. That is, as for the luminance signal 20, as is clear from the spectrum diagram in FIG.
Since the frequency band is different from that of the recording pilot signal f to be detected, this can be handled by using a filter (not shown).

As described above, according to the present invention, even in a device that records an audio signal on a track as a composite signal together with a video signal, etc., the pilot signal detection operation for tracking can be performed normally without causing deterioration of the audio signal. This can significantly improve the reliability of auto-tracking.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the recording state of pilot signals in a conventional tracking method. FIG. 2 is a block diagram of a conventional device. FIG. 3 is a diagram showing the structure of the recording section to which the present invention is applied. FIG. 4 is a diagram showing the format of a recording signal by the recording section of FIG. 3. FIG. 5 is a diagram showing the spectrum between signals. FIG. 6 is a block diagram showing one embodiment of the present invention. FIG. 7 is a diagram for explaining the operation of a switch provided in an embodiment of the present invention. FIG. 8 is a block diagram showing another embodiment of the invention. In the figure, 18 and 1b are magnetic heads, 6a and 6b are recording amplifiers, 7a and 7b are head amplifiers, 8a and 3b are switches, 21 is an audio signal, 22 is a video signal, 24 is a video signal cutoff switch, 27 and 28 are Signal distribution switch, 3
1 is an attenuator, f is a recording pilot signal, F is a reproduction pilot signal, and S is a no-signal area. Agent Shin Kuzuno - (1 other person)
1. Illustration 2. Illustration 3. Illustration 5. Illustration 6. Illustration 7. 110 - Fig. 8 - ■ Procedural amendment (self-motivated) 1995 5th post 6. 22El Commissioner of the Japan Patent Office 1, Indication of the case Patent application No. 58-49746 2, Name of the invention Magnetic recording and reproducing device 3, Representative Hitoshi Katayama of the person making the amendment Part 5, Detailed description of the invention in the specification subject to the amendment and drawings 66 Contents of the amendment (1) [Rotating magnetic head width direction] in lines 9 and 10 on page 2 of the specification is corrected to ``width direction of the rotating magnetic head.'' (2) [ in lines 4 and 5 of page 4 of the specification] "Reproduction pilot signal f and recording pilot signal @F" is "Reproduction pilot signal F and recording pilot signal f"
Correct to. (3) [Or delete head amplifiers 7a and 7bJ on page 4, lines 10 and 11 of the specification. (4) "Recording amplifiers 6a, 6b J [magnetic heads 1a, 1bJ
Correct to. (5) Figure 6 of the drawings is as attached. that's all

Claims (2)

[Claims] (1) In a rotary head type magnetic recording/reproducing device that puts the magnetic head in a reproducing state during a part of the recording period, reproduces and detects a pilot signal, and controls tracking based on this detection signal, the first magnetic head operates as a pilot signal. The second magnetic head is held in a recording state during a period in which the signal is reproduced and detected, and at least a modulated audio signal is selected from among the composite signals supplied to a recording amplifier connected to the second magnetic head. 1. A magnetic recording/reproducing device characterized by being provided with signal limiting means for attenuating or blocking other signals while leaving the other signals. (2) The signal limiting means includes switching means for extracting the audio signal from the composite signal, and switching the first magnetic head or the second magnetic head to the recording side or the reproduction side in conjunction with the switching means. 2. The magnetic recording and reproducing apparatus according to claim 1, further comprising switching means.