JPH0736204B2 - Magnetic recording device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording apparatus having a rotating magnetic head, and more particularly to a magnetic recording medium using a flying erase head and a rotating magnetic head mounted on a rotating drum. The present invention relates to a magnetic recording device for recording and erasing information signals on it.

[Conventional technology]

A well-known video tape recorder (VT
R), but in the VTR, a magnetic tape running system for running and driving a magnetic tape which is a magnetic recording medium, a rotary drum system having a rotary magnetic head for recording / reproducing information signals on / from the magnetic tape, and a video signal magnetically. It is configured by a signal processing circuit system for recording / reproducing on / from a tape.

Recently, miniaturization of VTRs for consumer use is rapidly progressing from those using 1/2 inch width tapes to so-called 8mm VTRs using 8mm width tapes. Along with this, the diameter of the rotary drum has been reduced, and the rotary transformer for transmitting a recording / reproducing signal or the like between the magnetic head and the signal processing circuit system has been downsized. However, when the rotary transformer having a plurality of channels is downsized, the crosstalk between the channels becomes large.

On the other hand, the erasing head, which was conventionally fixed to the magnetic tape running system, has come to be mounted on the rotating drum even in the VTR for consumer use. That is, erasing is performed by using a flying erase head (hereinafter referred to as FEH) mounted on a rotating drum. Especially 8mmV
In TR, since a recording medium having a high coercive force such as a metal tape is used, in order to perform erasing by FEH, an erasing current several times as large as the recording current of a normal video head is required.

[Problems to be solved by the invention]

As described above, when the VTR is downsized, the rotary transformer is downsized, and the crosstalk between the channels becomes an important issue. Especially in the 8mm VTR, the FEH erase signal is recorded in the range of 10MHz to 10MHz because it may record the PCM audio signal on the extension line of the video signal track at the same head.
If the crosstalk of the rotary transformer is large at the time of recording when set to about,
The erasing signal leaks, the error rate of the PCM audio signal increases during playback, and the playback sound quality deteriorates. Further, since the video recording signal is also adversely affected and the image quality is deteriorated, the crosstalk between the channels of the rotary transformer is a serious problem.

SUMMARY OF THE INVENTION In view of these problems, an object of the present invention is to provide a magnetic recording device capable of eliminating an adverse effect of an erase signal to the FEH on recording performed by another magnetic head.

[Means for solving problems]

A magnetic recording apparatus according to the present invention includes a plurality of heads, a recording circuit for supplying an information signal to at least one of the plurality of heads, and a flying erase head for erasing the information signal recorded on a recording medium. An erasing circuit that supplies an erasing signal to the flying erase head; a phase inverting circuit that inverts the phase of the erasing signal supplied to the flying erase head and supplies the erasing signal to at least one of the plurality of heads; A plurality of heads and a flying erase head are electrically coupled to the recording circuit and the erasing circuit, respectively, and a rotary transformer having independent channels is provided, and the phase is determined according to the position of the channels in the rotary transformer. Setting the head that supplies the output signal of the inverting circuit A.

[Work]

In the present invention, when the erasing signal supplied to the FEH causes the magnetic head crosstalk for recording via the rotary transformer, a signal obtained by inverting the phase of the erasing signal by the mixing circuit is equivalent to the crosstalk, Crosstalk can be canceled by superimposing it on the information signal to be recorded.

〔Example〕

FIG. 1 is a circuit block diagram of a VTR according to one embodiment of the present invention, FIG. 2 is a diagram showing a channel arrangement of a rotary transformer of this embodiment, and FIG. 3 is a magnetic head and a magnetic head on a rotary drum of this embodiment. FIG. 4 shows the FEH mounting position, and FIG. 4 is a timing chart for explaining the operation of this embodiment.

In FIGS. 1, 2, and 3, F, L, and R are FEH and a magnetic head, respectively, and T _F , T _L , and T _R are rotary transformer channels for them. Further, T is a rotary transformer, “FEH OSC” is an oscillation circuit that forms an FEH erasing signal, and “PCM REC” is an audio signal A _IN to be recorded on the PC.
A PCM signal processing circuit that converts M into a PCM audio signal for recording, "Video REC" is an information signal processing circuit for converting a video signal V _IN to be recorded and an audio signal A _IN into a signal form suitable for recording, A _F , A _L and A _R are amplifiers respectively, A ₄ is a phase inverting circuit, A ₅ is a mixing circuit, SW ₁ and SW ₂ are switching switches, SW ₃ is switches, I _F , I _L and I _R are amplifiers respectively. Output currents of A _F , A _L , and A _R , and each channel of the rotary transformer.
Supplied to T _F , T _L and T _R.

The video signal V _IN and the audio signal A _IN are input to the signal processing circuit "Video REC", and the luminance signal is FM-modulated and the color signal is converted into the low-pass color according to the format of the 8 mm VTR, and the audio signal is converted into the audio signal. The center is FM-modulated at 1.5 MHz and the recorded information signal is output. The recorded information signal also includes a known tracking pilot signal.

In addition, the PCM conversion circuit "PCM REC" has an audio signal A _IN
Is input, the audio signal is converted to PCM, then time-compressed, and a PCM audio signal to be recorded before the video area is generated.

Next, the operation of the circuit block diagram shown in FIG. 1 will be described using the timing chart of FIG.

In FIG. 4, 30PG is a head switching signal which is synchronized with the rotation phase of the rotating drum. During the High level, the R head contacts the video signal recording area of the magnetic recording medium,
L head contacts between w levels. Since the rotary transformer is connected to the FEH, L head and R head channels from the outside, when recording, especially from the FEH channel to L
The crosstalk of the head channel becomes a problem. Therefore, during the period when the erasing current I _F flows, the phase of the current I _F is inverted to the recording current I _L of the L head via the mixing circuit A ₅ , and a signal (−ΔI _{Let's say F} ). Therefore, ΔI _F due to crosstalk is canceled in the recording current flowing through the L head.

That is, from the time 30PG goes high to the end of the supply of the erase current to FEH, I _L is set to −ΔI _F , and when the L head reaches the PCM area, only the PCM signal is sent. , V signal when reaching the video area, then FEH
When the erasing current supply to V + (-△ _IF ) starts
In, and the L head passes by video area, again - becomes △ I _F.

So, for example, L head is in the video area and FEH is O.
The currents actually flowing in the current L head when it is N _{is, V + (- △ I F} ) + △ I F = V becomes, so that the crosstalk component from the rotary transformer is Cancel.

Further, in order to switch the recording current in this manner, the states of the switching switches SW ₁ , SW ₂ and the switch SW ₃ are shown on the timing chart. For the switching switches SW ₁ and SW ₂ , PCM is connected to the "PCM REC" circuit, Video is connected to the "Video REC" circuit, and GND is "PCM RE".
Indicates that there is no signal input, not connected to either C "or" Video REC "circuit.

Next, details of this switching circuit will be described with reference to FIGS.

FIG. 5 is a concrete block diagram of the essential parts of one embodiment of the VTR according to the present invention, and FIG. 6 is a diagram showing its timing chart.

In FIG. 5, the control inputs of AS _{1 to} AS ₇ are High respectively.
An analog switch that turns on at the level and turns off at the low level,
MM ₁ and MM ₂ are mono-multivibrators triggered by rising edges, MM ₃ and MM ₄ are mono-multivibrators triggered by falling edges, IN ₁ and IN ₂ are inverters, and F / F is falling edges. An edge-triggered RS flip-flop, AND is a 2-input AND gate, NOR is a 2-input NOR gate, and R ₁ and R ₂ are resistors respectively.

Resistors R ₁ and R ₂ in FIG. 5 are mixed circuits A in FIG.
Corresponds to ₅ . The resistors R ₁ and R ₂ mix a signal from the "Video REC" circuit with a signal obtained by inverting the phase of the erase signal current to the FEH at a predetermined mixing ratio, and the recording current flowing in the L head is The crosstalk from the transformer will be canceled. The resistors R ₁ and R ₂
The resistance value of may be determined according to the crosstalk amount of the rotary transformer.

In the timing Chiya over bets Figure 6, AS ₂ ~AS ₇ shows a control signal of each analog switch AS ₂ ~AS _7, F / F corresponds to the control signal of the analog Sui Tsui AS _1. In this timing chart, the mono-multi-vibration rate MM ₁ according to the head switching signal synchronized with the rotation phase of the rotating drum.
Conditions, such as the control signal of the output signal and the analog switch AS ₂ ~AS ₇ of ～MM ₄ is shown.

Next, the operation of the principal block diagram shown in FIG. 5 will be described using the timing chart of FIG.

When 30PG becomes Hihg level, mono multivibrator MM
₁ and MM ₂ are switched to the high level, and the mono-multivibrates MM ₃ and MM ₄ are in the low level state. The output of the mono-multivibrator MM ₁ is input to the AND gate AND via the inverter IN ₂ and is ANDed with the output signal of 30PG, so that the output maintains the low level. Accordance connexion, control signal analog switch AS ₂ maintains the Low level, analog switch AS ₂ remains OFF. Similarly, the RS flip-flop F / F maintains the Hihg level, the analog switch AS ₁ remains ON, and the analog switch AS ₇ remains OFF. Further, the analog switches AS ₃ and AS ₅ are turned off, and the analog switches AS ₄ and AS ₆ are turned on.

Therefore, the output of the FEH OSC circuit is mixed with the current I _L via the analog switch AS ₁ , the phase inversion circuit A ₄ , the resistors R ₁ and R ₂ , and the analog switch AS ₄ . That is, the current I _L is mixed with the signal obtained by inverting the phase of the erase signal current to FEH, so that the recording current flowing in the L head becomes (−ΔI _F ) + I _F = 0, and The crosstalk will be canceled. In the same manner, follow the timing Chiya over preparative shown in FIG. 6 connexion, the analog switch AS ₁ ~AS ₇ is sequentially switched, circuit operation shown in the timing Chiya over preparative of FIG. 4 is performed.

Further, FIG. 7 is a diagram showing a specific circuit of the phase inverting circuit A ₄ . Q is a transistor, R _{3 to} R ₆ are resistors, and C ₁ and C ₂ are capacitors. The frequency characteristic of this circuit may be a substantially flat characteristic with respect to the input signal band.

〔The invention's effect〕

As described above, the present invention includes the phase inversion circuit that inverts the phase of the erase signal supplied to the FEH, and the mixing circuit that mixes the information signal recorded on the magnetic recording medium and the output signal from the phase inversion circuit. At the time of recording, the output of the mixing circuit is supplied to the magnetic head for recording on the magnetic recording medium. Therefore, when the erasing signal to the FEH causes the magnetic head crosstalk for recording through the rotary transformer, this crosstalk is generated. By making it possible to obtain a magnetic recording device, it is possible to prevent the adverse effect of the leakage of the erasing signal for recording performed by another magnetic head.

[Brief description of drawings]

FIG. 1 is a circuit block diagram of a VTR according to an embodiment of the present invention, FIG. 2 is a diagram showing a channel arrangement of a rotary transformer of the VTR of FIG. 1, and FIG. 3 is a rotary drum of the VTR of FIG. FIG. 4 is a timing chart for explaining the operation of the VTR shown in FIG. 1, FIG. 5 is a concrete circuit block diagram of the main part of the VTR shown in FIG. 1, and FIG. Fig. 5 Timing chart of each part, Fig. 7 shows 5
It is a figure which shows the concrete circuit of the phase inversion circuit in a figure. In the figure, F is FEH, L and R are magnetic heads, and "FEH OSC"
Is the oscillator circuit, "PCM REC" is the PCM signal processing circuit, and "Video
REC "is an information signal processing circuit, A _F , A _L and A _R are amplifiers, A ₄ is a phase inversion circuit, A ₅ is a mixing circuit, T is a rotary transformer,
T _F , T _L and T _R are each channels of the rotary transformer T, respectively.

Claims (1)

[Claims] 1. A plurality of heads, a recording circuit for supplying an information signal to at least one of the plurality of heads, a flying erase head for erasing the information signal recorded on a recording medium, and the flying. An erasing circuit for supplying an erasing signal to an erasing head; a phase inverting circuit for inverting the phase of the erasing signal supplied to the flying erasing head and supplying the erasing signal to at least one head of the plurality of heads; The flying erase head and the recording circuit and the erasing circuit are electrically coupled to each other, and a rotary transformer having independent channels is provided, and an output signal of the phase inversion circuit is output according to the position of the channel in the rotary transformer. Magnets characterized by setting the head to supply Qi recorder.