JPH0618042B2 - Magnetic recording / reproducing device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus, and more particularly to an audio signal head for recording an audio signal superimposed on a bias signal in a deep portion of a magnetic layer, and formed by the audio signal head. The present invention also relates to a magnetic recording / reproducing apparatus having a video signal head for recording a video signal by forming a video track on the surface layer of the magnetic layer above the audio track and a rotation erasing head.

2. Description of the Related Art In the Japanese Patent Application No. 62-261319 (invention title “magnetic recording device and magnetic recording / reproducing device”), the present applicant frequency-multiplexes an FM audio signal and a PCM audio signal in a deep portion of a magnetic tape. Then, a high-frequency bias signal is superposed and recorded on the magnetic tape, and then a video signal consisting of a frequency-modulated luminance signal and a low-frequency conversion carrier color signal is frequency-multiplexed and recorded on the surface layer of the magnetic tape, and the recorded signal thus recorded. We have proposed a magnetic recording / reproducing device for reproducing data.

Some of the rotating cylinders of other VTRs including the above magnetic recording / reproducing apparatus are provided with a rotary erasing head for erasing previously recorded audio signals and video signals along recording tracks. This rotation erasing head has, for example, 4M
The erase signal of Hz was supplied from the outside of the rotary cylinder via the rotary transformer, and the winding for the rotation erasing head of the rotary transformer was wound between the windings for the audio signal.

As described above, a high frequency erase signal current is supplied to the rotary erase head, and the erase current is recorded in the deep portion of the magnetic layer in order to securely erase the recorded signal. A larger current is required than the high frequency bias signal of the audio signal being processed. Therefore, if no measures are taken, crosstalk occurs between this erase signal and the high-frequency bias signal for deep recording, causing intermodulation distortion in the audio signal recorded in the deep portion of the magnetic layer. As a result, the signal quality deteriorates.

As a means to prevent this crosstalk, it is conceivable to add a short ring, but this will increase the cost and reduce the winding interval of the rotary coil, which causes crosstalk to other signals. There is a problem that deterioration of

In addition, this erase signal also causes crosstalk with the video signal especially in the rotary transformer, so that cross modulation distortion also occurs in the video signal and the signal is deteriorated, and when the video signal thus recorded is reproduced, moire is displayed on the screen. There was a problem that it would occur.

The present invention has been made in view of the above points, and magnetic recording / reproduction capable of preventing the deterioration of the signal by eliminating the influence of the erase signal on the audio signal and the video signal without adding a short ring or the like. The purpose is to provide a device.

Means for Solving the Problems In a magnetic recording / reproducing apparatus according to the present invention, a bias signal for superimposing an audio signal at the time of recording and an erasing signal have the same frequency, and a recording audio signal and a recording video signal are passed through a rotary transformer. When transmitting and receiving an erasing signal, the first winding for the audio signal head among the windings constituting the rotary transformer is used as the second winding for the rotation erasing head and the third winding for the video signal head. A first core that is provided between the wire and the first and second windings, and a second core that winds the third winding are separately provided.

Further, the bias signal or the erasing signal (or the erasing signal) may be provided on either or both of the preceding stage of the rotary transformer on the recording video signal transmission path or the closed loop constituted by the winding of the rotary transformer and the winding of the video signal head. Bias signal trapping means for trapping frequencies of the same frequency) are provided.

The erase signal has a level higher than that of the high frequency bias signal of the audio signal normally recorded in the deep portion of the magnetic layer, but by matching the frequency of this erase signal and the frequency of the high frequency bias signal, both signals are Even if crosstalk occurs between them, it is possible to prevent the occurrence of intermodulation distortion due to the erase signal in the audio signal.

In addition, the configuration of the windings that form the rotary transformer is such that the windings for the erasing signal are arranged by arranging the windings for the audio signal between the windings for the erasing signal and the winding for the video signal, which have a large level. It is possible to greatly separate the distance between the image signal and the video signal winding, and it is possible to reduce the influence of the erase signal on the video signal.

Further, since the frequencies of the high frequency bias signals of the erase signal and the audio signal are equal, the core for winding the erase signal winding and the audio signal winding and the core for winding the video signal winding are separated from each other. By this, the cross modulation distortion of the video signal due to the crosstalk between the erase signal and the audio signal and the video signal is further reduced.

Even with the above configuration, even if the video signal is affected by the erasing signal or the audio signal through the winding of the rotary coil, it is in the preceding stage of the rotary coil or the rotary coil on the transmission path of the recording video signal. The erase signal and the high frequency bias signal are trapped by the bias signal trapping means provided in either one or both of the closed loops consisting of the winding of the image signal and the winding of the video signal head. The effect on the signal is further reduced.

Embodiment FIG. 1 is a block system diagram showing an embodiment of the device of the present invention. In the figure, a portion above the one-dot chain line A is a magnetic recording device (recording system), and a portion including a portion below A is a magnetic recording / reproducing device including a reproducing system.

To describe the present embodiment, a color video signal of the standard color system is input to the terminal 25, and the video signal processing circuit 26
Is supplied to. The video signal processing circuit 26 separates the luminance signal and the carrier color signal by a known means, and frequency-modulates the luminance signal (FM) obtained by frequency-modulating the carrier wave with this luminance signal.
Luminance signal), and the carrier color signal is subjected to low-frequency conversion to generate a low-frequency conversion carrier color signal, and both of these signals are frequency-division-multiplexed to obtain a signal having a frequency spectrum as shown in FIG. 2 (A). Output. In FIG. 2 (A), I is an FM luminance signal, and its carrier frequency band is 5.4 MHz to 7.0 MHz. II is a low-frequency conversion carrier color signal, and the low-frequency conversion color subcarrier frequency is almost
It is 629 kHz. The above-mentioned video signal for recording is the recording amplifier 2
7 and a trap circuit 90a which is one of the main parts of the present invention, and is supplied to the video rotary heads 28a and 28b. Detailed description of the trap circuit 90a will be given later.

Further, the video signal processing circuit 26 supplies the color video signal of the standard color system as it is to the sync signal separation circuit 29. The sync signal separation circuit 29 separates the vertical sync signal and supplies it to a servo circuit 30 described later.

On the other hand, the left channel analog audio signal and the right channel analog audio signal coming into the terminals 31a and 31b are sent to the noise reduction (NR) circuits 70a and 70b via the switch means 69a and 69b, respectively.
After the dynamic range is halved, pre-emphasis circuits 71a and 71b are provided with pre-emphasis characteristics, and limiters 72a and 72b cut off signals of a predetermined level or higher. Limiters 72a, 72b
Is sent to FM modulators 73a and 73b, is FM-modulated by carrier waves of 1.3 MHz and 1.7 MHz, respectively, and is sent to mixer 75 after passing through bandpass filters 74a and 74b.

On the other hand, after the unnecessary high frequency components exceeding the audible frequency band are removed by the low frequency filters 32a and 32b via the switch means 69a and 69b, respectively, the sample and hold of the sampling frequency is, for example, 47.952 kHz (= 48 KHz ÷ 1.001). A / D modulators 34a, 34b via circuits 33a, 33b
, And is linearly quantized to a quantization bit number of 16 bits and then coded to be a PCM audio signal. The PCM audio signals for each of the left and right channels are sent to the encoder 3
5 is supplied.

The encoder 35 has an even-numbered sample ES in one field period and an odd-numbered sample OS, and is shown in FIG.
The error detection and correction codes P and Q are generated in the format shown in FIG.

In FIG. 3 (A), data DATA1 and DATA2
Is a sample ES, OS respectively subjected to time axis compression and interleaving, and is a horizontal word unit (1
Data of each row (word is 8 bits) DATA1, DAT
The parity Q of 6 rows of 8 × 30 (= 8 × 6 × 5) bits is repeated by repeatedly performing a predetermined operation on each of 10 words of A2 (8 × 50 bits each). To get Also, the encoder 35 performs a predetermined operation for eight columns in the vertical direction, that is, for every 32 words of data DATA1, DATA2, and parity Q of 1 word (= 8 bits) for each row, and each column of 4 words has 8 × 4 bits. Parity P is generated.

Next, the data DATA1 and DATA2 and the parities P and Q are divided into eight columns of 36 words each, and immediately before each of the 36 words, each 8 bits (= 1 word as shown in FIG. 3B). ) Synchronization signal SYNC, identification signal ID,
Address signal ADDR, block parity signal PARI
TY is added to form a 40-word data block at the front. The synchronization signal SYNC indicates the start of each data block. The address signal ADDR indicates the order of each data block in the digital audio signal for one track (that is, 130 data blocks). The block parity signal PARITY is PARITY = IDADDR
This is a signal for error detection obtained in. Here, it is an addition operator modulo 2.

Data DATA1, DATA2 shown in FIG. 3 (A) in 130 data blocks of the data area shown in FIG. 3 (C).
And the parities P and Q are transmitted, but a preamble for clock recovery for 4 data blocks and a postamble for 2 data blocks are added before that.

In this way, the encoder 35 generates a digital audio signal having a signal format of 136 data blocks (= 43,520 bits) in total as shown in FIG. 3 (C), and this is generated in one field period (= 1 / 59.94 seconds). To transmit. Therefore, the transmission bit rate of the digital audio signal is 2.6086 (= 136
× 320 × 59.94) Mdps.

The encoder 35 is field-synchronized with the recorded video signal by the output signal of the servo circuit 30.

An offset four-phase differential PSK modulator (OQDPSK modulator) 36 converts the digital audio signal into a serial-parallel signal and outputs it as two code strings alternately.
Phase shift means for shifting one code sequence from each other by ½ of one time slot and two code sequences from the phase shift means are received as modulation signals, and their phases are 90 degrees with each other at a predetermined frequency fc.
A known balanced modulation means for separately modulating two carrier waves with suppressed carrier amplitude, and a synthesis circuit for synthesizing two amplitude-modulated waves from the balanced modulation means and outputting a digital voice signal subjected to OQDPSK modulation. It is configured.

The carrier frequency fc is, for example, a horizontal scanning frequency f.
It is selected to be about 3.0MHz, which is 191 times the frequency of _H. Therefore, the frequency spectrum of the output digital audio signal of the OQDPSK modulator 36 has the maximum level at the carrier frequency fc, and the transmission bit rate is 2.6086 Mb.
Since it is ps, ± n × 1.30 MH for carrier frequency fc
It becomes a known comb-shaped spectrum which becomes 0 at a frequency position away from z (= 2.6086 MHz / 2). However, the above n is a natural number. Therefore, the output digital voice signal of the OQDPSK modulator 36 has a pass band width of about 3.0 MHz which is band-limited to remove unnecessary frequency components and which does not cause intersymbol interference. After passing through a bandpass filter 37 selected to have a bit rate of about 0.7 times, the band is limited to a digital voice signal having a frequency spectrum as shown by III in FIG.
8 is input to the mixer 75, frequency-division-multiplexed with the FM audio signal, and then supplied to the bias superimposing circuit 39, where the high frequency bias signal generated in the bias superimposing circuit 91 is superposed.

The bias superimposing circuit 39 is configured as shown in FIG. 4 or FIG. 5, for example. 4 and 5, the same components as those in FIG. 1 are designated by the same reference numerals, and in FIG. 5, the same components as those in FIG. 4 are designated by the same reference numerals.

In the bias superposing circuit 39 shown in FIG. 4, in the adding circuit 45, a bias oscillator 46 is added to an audio signal obtained by mixing the OQDPSK-modulated digital audio signal from the terminal 38 and the frequency-modulated FM audio signal.
For example, superimpose a high frequency bias signal of 10.8MHz,
This superimposed signal is output to the terminal 40 through the recording amplifier 47.

On the other hand, the bias superposition circuit 39 shown in FIG.
The OQDPSK-modulated digital audio signal and the frequency-modulated FM audio signal from
After being taken out through the wrap circuit, the capacitor 51 and the capacitor 51 add and synthesize (superimpose) with the high frequency bias signal taken out from the bias oscillator 46 through the capacitor 52, and then output to the terminal 40.

The circuit shown in FIG. 5 has a well-known circuit configuration for bias recording. The trap circuit blocks the transmission of a high-frequency bias signal to the recording amplifier 47 side, and also the capacitor 52.
Thus, transmission of the digital audio signal and the FM audio signal to the bias oscillator 46 side is blocked. The recording amplifier 47 of the bias superimposing circuit 39 shown in FIG. 5 can use an inexpensive recording amplifier as compared with the expensive recording amplifier of wide band and high output required in the bias superimposing circuit 39 shown in FIG.

Next, the noise spectrum reduction effect by the high frequency bias recording will be described. About 3.0MHz ± 1.3M as shown in Fig.6
OQDPSK-modulated digital audio signal I and frequency-modulated FM audio signal II with a frequency spectrum of Hz
However, without superimposing a high frequency bias signal, it was recorded directly on the deep part of the magnetic layer of the magnetic tape by a rotary head for audio like a conventional device, and a video signal was recorded on the surface part of the magnetic layer. When the magnetic tape is reproduced by the rotary head for voice, the modulated digital voice signal and F
The frequency spectrum of the M audio signal is as shown in FIG. 7 (A).

In FIG. 7 (A), fsc is a color subcarrier frequency of the low-frequency conversion carrier color signal, which is, for example, 629 kHz, and the low-frequency conversion carrier color signal band is affected by the intermodulation distortion as shown by a broken line V. Since the noise spectrum exists at a large level and occurs in the low frequency region where the azimuth loss effect is reduced, it also occurs in the reproduced video signal of the video rotary head and deteriorates the color S / N. Further, such intermodulation distortion is caused by the non-linearity of the tape, and the distortion caused thereby deteriorates the error rate of the digital signal as described above, and the ratio of the carrier wave to the noise of the FM audio signal is reduced. It also deteriorates the C / N shown.

On the other hand, the frequency spectrum O shown in FIG.
When the QDPSK-modulated digital audio signal and FM audio signal are recorded by superimposing a high frequency bias signal of 10.8 MHz according to the present invention, the frequency spectrum of the reproduced modulated digital audio signal is shown in FIG. 7 (B). As a result, it is confirmed by experiments that the noise spectrum in the vicinity of the low-frequency conversion color subcarrier frequency fsc among the noise spectrum due to the intermodulation distortion of the low-frequency conversion carrier color signal band surrounded by the broken line VI is significantly reduced. I was raped. The high frequency components of FIG. 7 (B) are equalized by the reproduction equalizer into the spectrum of FIG. 2 (B).

Further, instead of OQDPSK modulation, four-phase differential PSK modulation (QDPSK modulation) is used to directly perform deep recording on a digital audio signal having a frequency spectrum similar to that shown in FIG. 6, without superimposing a high frequency bias signal, and recording it. Similarly, in the frequency spectrum when reproduced, the noise spectrum in the vicinity of the low frequency conversion color subcarrier frequency fsc is significantly reduced. Therefore, it can be applied not only to the OQDPSK-modulated digital audio signal but also to the QDPSK-modulated digital audio signal.
In addition to the QDPSK or QDPSK modulation format, the present invention can be similarly applied to a two-phase or eight-phase offset DPSK modulation or a DPSK-modulated digital audio signal.

The superimposed signal of the audio signal and the high frequency bias signal taken out from the terminal 40 is the audio rotary head 41 of FIG.
a and 41b, respectively. Rotary head 41 for voice
18a and 41b are attached to the rotating surface of the rotating cylinder (not shown).
They are mounted so as to oppose each other at 0 °, and are mounted at a fixed angle ahead of the mounting positions of the video rotary heads 28a and 28b. In addition, the rotary head 41 for voice
The azimuth angles of a and 41b are + 30 ° on one side and −30 ° on the other side.
One of the azimuth angles of 8b is + 6 ° and the other is -6 °.

The motor (not shown) that rotates the rotary cylinder is
Based on the output signal of the servo circuit 30 to which the vertical synchronizing signal from the synchronizing signal separating circuit 29 is supplied, it rotates in phase synchronization with the vertical synchronizing signal.

As a result, the rotary heads for voice 41a, 41b
The digital audio signal and the FM audio signal are subjected to high-frequency bias recording even to a deep portion of the magnetic layer of the magnetic tape 43 which runs while being wound around the rotary cylinder over an angle range of a little over 180 ° to form an audio track, After that, the video rotary head 28 is provided on the surface of the magnetic layer on the audio track.
A video signal for recording is recorded by a and 28b to form a video track.

At the same time, the control head 42 forms a control track along the longitudinal direction of the magnetic tape and records the control pulse generated from the vertical synchronizing signal extracted from the servo circuit 30.

Next, the main part of the present invention will be described. The high frequency bias signal from the bias oscillator 91 is supplied to the bias superposition circuit 3
In addition to being supplied to 9, the rotary erasing head 92 is also supplied as an erasing signal via the rotary transformer 100 (see FIG. 9). The rotary erasing head 92 is provided on the rotary surface of the rotary cylinder together with other rotary heads, and an erasing signal is supplied at the time of recording so that a signal previously recorded on the magnetic tape before recording can be recorded on a track on the magnetic tape. Erase along.

Since this erase signal has a higher level than the high frequency bias signal that is normally superimposed in the bias superimposing circuit 39, setting the erase signal at an arbitrary frequency causes crosstalk between the audio signal and the video signal in the rotary transformer. This causes signal deterioration. However, by using the signal from the bias oscillator 91 as the erasing signal as shown in FIG. 1, the frequencies of the erasing signal and the high frequency bias signal can be matched to, for example, 10.8 MHz, and crosstalk occurs in the rotary transformer. Even if this occurs, cross modulation distortion does not occur and signal deterioration can be reduced.

Further, the core of the rotary transformer provided on the lower drum of the rotary cylinder (the portion of the rotary cylinder that is fixed to the chassis) has the structure shown in FIG.
In the figure, a core 95 is a winding core for erasing signals and audio signals, and 96 is a winding core for video signals, and both are magnetically separated by a protruding member 97 of a lower drum. A winding for an erase signal is provided on the inner peripheral side of the surface of the core 95.
Is concentrically wound over several turns, and a voice signal winding is also wound on the outer peripheral side thereof. Also core 96
A video signal winding is wound on the surface (outer periphery of the protruding member 97) concentrically with the core 96 (and the core 95) over several turns.

As described above, the core 95 for the erase signal / audio signal winding and the core 96 for the video signal are separately provided, and in addition, the audio signal core is provided between the erase signal winding and the video signal winding. By providing the windings, the crosstalk between the video signal and the erase signal can be effectively reduced.

As shown in FIG. 1, FIG. 9A shows a stage after the recording amplifier 27 (between the recording amplifier 27 and the rotary transformer 100).
The trap circuit 90a provided in FIG. 2 is extracted and shown. FIG. 2B shows the winding of the video signal of the rotary transformer 100 in the rotary cylinder, the head 28a (or 28b) for the video signal, and the closed loop. 3 shows the trap circuit 90b provided in the above. In the figure, the right side of the one-dot chain line 1 is the inside of the rotating cylinder (the inside of the upper drum rotating above the lower drum), and the left side is the outside of the rotating cylinder (including the lower drum).

In both the trap circuits 90a and 90b, the values of the coil and the capacitor are set so as to trap the frequency 10.8 MHz (that is, the bias signal frequency) of the erase signal,
By trapping the erase signal and the high frequency bias signal induced in the rotary transformer 100, the impedance with respect to this frequency is increased, and as a result, the influence on the video signal is reduced.

By taking the above means, it is possible to effectively reduce the influence of the erase signal (and the high frequency bias signal) on the video signal, and it is possible to prevent intermodulation distortion due to the erase signal from occurring in the video signal. .

Next, the operation of the reproducing system for reproducing the magnetic tape 43 recorded by the above recording system will be described. From the audio track formed in the deep portion of the magnetic layer of the recorded magnetic tape 43, the rotary heads 41a and 41b are used. The modulated digital audio signal and the FM audio signal which are alternately reproduced are preamplified by the preamplifier 55.
Is supplied to. At the same time, the video signal reproduced alternately by the rotary heads 28a and 28b from the video track of the magnetic tape 43 is supplied to the switching amplifier 56. Further, the control pulse reproduced by the control head 42 from the control track of the magnetic tape 43 is supplied to the servo circuit 30. The servo circuit 30 controls the rotation of the rotary cylinder so that the reproduction control pulse can be synchronized with the reference frequency signal.

The switching amplifier 56 amplifies the reproduced video signals of the rotary heads 28a and 28b and switches the reproduced video signals into a continuous signal, and supplies this signal to the video signal processing circuit 58 via the preamplifier 57. The video signal processing circuit 58 band-separates and extracts the FM luminance signal and the low-frequency-converted carrier color signal from the reproduction signal by a known means, performs FM demodulation to obtain the brightness signal, and obtains the carrier color signal by frequency conversion. The carrier color signal is superimposed on the luminance signal and output as a standard color reproduction color video signal from the terminal 59.

On the other hand, the preamplifier 55 amplifies the reproduced audio signal in which the digital audio signal and the FM audio signal from the rotary heads 41a and 41b are mixed and switches the amplified reproduced audio signal into a continuous signal, thereby reproducing the equalizer 80 and the band-pass filters 81a and 81a.
supply to b. The outputs of the bandpass filters 81a and 81b are passed through limiters 82a and 82b, respectively, and FM demodulators 83a and 83, respectively.
FM demodulation at b, de-emphasis circuit 84
After the de-emphasis characteristic is added at a and 84b, the dynamic range is restored to the original by the noise reduction circuits 85a and 85b, and the output terminals 86a and 86b.
The audio signals of the left channel and the right channel are extracted from b.

The reproduction equalizer 80 reinforces the attenuated high frequency component and then supplies it to the band pass filter 60. The reproduced modulated digital voice signal of the frequency spectrum shown in FIG. 2 (B) which is band-separated by the band-pass filter 60 is supplied to the OQDPSK demodulator 61 where it is subjected to the known OQDPSK demodulation to be a digital voice signal. It is supplied to the decoder 62.

The decoder 62 is supplied from the servo circuit 30 with a synchronization signal generated from a pulse phase-synchronized with the rotation of the rotary cylinder in order to know the first reproduction position of the digital audio signal of each track. The reproduced digital audio signal is subjected to processing such as error correction, time axis correction, time axis expansion and deinterleave by the decoder 62, and each sample is A
The signals are combined in the same order as in the D / D conversion and separated into a left channel digital audio signal and a right channel digital audio signal.

The digital audio signals of the left and right channels are converted into analog signals by the D / A converters 63a and 63b, respectively, and then noise components generated at the time of D / A conversion are removed by the deglitcher circuits 64a and 64b. 65b
The unnecessary high frequency components exceeding the audible frequency band are removed by.
As a result, the left channel to the terminals 66a and 66b,
The right channel analog audio signals are output separately.

EFFECTS OF THE INVENTION As described above, according to the present invention, since the frequency of the erasing signal sent to the erasing head is equal to the frequency of the high frequency bias signal of the audio signal, the audio signal is free from intermodulation distortion due to the erasing signal. Deterioration is reduced, and the audio signal core of the rotary transformer is magnetically separated from the audio signal core and the audio signal core, and the audio signal winding of the rotary transformer is the erase signal winding and the video signal. By arranging it between the windings for use, the influence of the erase signal of a large level on the video signal is reduced, and by further providing the bias signal trap means in the transmission path of the recording video signal, it is possible to reduce the influence of the signal via the rotary transformer. Since it is possible to trap the erase signal or the high frequency bias signal picked up by, the influence of the erase signal and the audio signal on the video signal is further reduced, The intermodulation distortion of the video signal is reduced, and so-called moire that appears on the screen can be prevented.

[Brief description of drawings]

FIG. 1 is a block system diagram of an embodiment of the device of the present invention, and FIG.
1 is a diagram showing an example of a frequency spectrum of a signal of each part of the block system shown in FIG. 1, FIG. 3 is a signal format diagram for explaining the operation of an encoder in the block system shown in FIG. 1,
4 and 5 are block system diagrams each showing an example of a bias superimposing circuit in the block system shown in FIG. 1, and FIG. 6 is a diagram showing an example of a frequency spectrum of a recording signal to an audio track, and FIG. 8A and 8B are views showing the frequency spectrum of the reproduced signal when deep recording is performed on the OQDPSK-modulated digital audio signal by the conventional device and the device of the present invention, and FIG. FIG. 9 is a perspective view showing the core of the rotary transformer, and FIG. 9 is a circuit diagram of the trap circuit. 25 ... Color video signal input terminal, 28a, 28b ... Video rotary head, 31a, 31b ... Analog audio signal input terminal, 34a, 34b ... A / D converter, 35 ...
Encoder, 36 ... OQDPSK modulator, 39 ... Bias superposition circuit, 41a, 41b ... Voice rotary head, 43 ... Magnetic tape, 45 ... Adding circuit, 46 ...
Bias oscillator, 47 ... Recording amplifier, 50 ... Trap circuit coil, 51 ... Trap circuit capacitor,
73a, 73b ... Frequency modulators, 74a, 74b, 8
1a, 81b ... bandpass filter, 75 ... mixer, 80
...... Reproduction equalizer, 83a, 83b …… Demodulator (FM demodulator), 90a, 90b …… Trap circuit, 91 …… Bias oscillator, 92 …… Rotation erasing head, 95, 96 ……
Core, 97 ... Projection member, 100 ... Rotary transformer.

Claims (4)

[Claims] 1. An audio signal head for recording or reproducing an audio signal superimposed on a bias signal in a deep portion of a magnetic layer,
A video signal head for recording or reproducing a video signal by forming a video track on a surface layer portion of the magnetic layer above the audio track formed by the audio signal head, and the magnetic layer by supplying an erase signal of a predetermined frequency. In a magnetic recording / reproducing apparatus having a rotary erasing head for erasing the audio signal and the video signal recorded in, the frequency of the erasing signal supplied to the rotary erasing head is equal to the bias signal, and the recording audio signal A first transformer for an audio signal head, which is provided with a rotary transformer for transmitting and receiving a recording video signal and an erasing signal, and which constitutes the rotary transformer.
Magnetic recording / characteristics, wherein the winding is provided between a second winding for a rotation erasing head forming the rotary transformer and a third winding for a video signal forming the rotary transformer. Playback device. 2. The rotary transformer comprises a first core around which a first winding for an audio signal head and a second winding for a rotation erasing head are wound, and a third core for a video signal head. 2. The magnetic recording / reproducing apparatus according to claim 1, wherein the first core around which the winding is wound comprises a second core that is magnetically separated. 3. A magnetic recording / reproducing apparatus according to claim 1, wherein a first bias signal trap means is provided in the recording video signal transmission path before the rotary transformer. 4. A second bias signal trap means is provided in a closed loop constituted by a winding of a video signal head and a rotary transformer on a recording video signal transmission path. The magnetic recording / reproducing apparatus according to any one of claims.