JPS6391801A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To reduce a crosstalk at the time of recording/reproduction between adjacent magnetic heads, comparing with a conventional one, by opening between winding terminals of the magnetic head except that which is being in an operating state at the time of recording or at the time of reproduction. CONSTITUTION:At the time of recording a frame, changeover switches 18, 20 are switched to a contact (a) side by a control signal. Simultaneously, by the pulse signal from a pulse generating circuit 17, the video signal of an odd field is recorded in a period in which a transistor Q1 becomes an ON state. In the next period, a transistor Q2 becomes an ON state, therefore, the video signal of an even field is recorded. In this way, frame recording is executed to two tracks of a magnetic disk. On the other hand, at the time of reproducing a frame, the changeover switches 18, 20 are switched to a contact (b) side by a control signal, and in the same way at the time of recording, the video signal of an even field and the video signal of an even field are reproduced alternately at every one vertical scanning period by magnetic heads 10A, 10B are reproduced, and the frame reproduction is executed.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a disk-shaped magnetic recording medium that is rotationally driven by operating a plurality of adjacently arranged wire-wound magnetic recording/reproducing heads in chronological order. The present invention relates to a magnetic recording and reproducing apparatus such as an electronic still camera and a tape type magnetic recording apparatus that record a plurality of different signals on a magnetic recording medium or reproduce the signals from the magnetic recording medium.

[Background of the invention]

For example, in a magnetic recording and reproducing device that records or reproduces a video signal on a rotating magnetic recording medium such as a magnetic disk, frame recording is performed, or when reproducing a frame-recorded video signal, the rotation of the rotating magnetic recording medium relative to the magnetic head is performed. The speed must be high enough. From this point of view, generally speaking, the recording of one field of video signals is the limit per rotation of a rotating magnetic recording medium, and in order to perform frame recording, two adjacent magnetic heads are used.
Normally, odd field signals are recorded on one side of the recording trunk of a book during the first revolution, and even field signals are recorded chronologically on the other recording track using each head during the next revolution. .

In order to improve the recording density in a conventional magnetic recording/reproducing device that performs frame recording using two magnetic heads, the recording track pitch must be shortened and the interval between the two magnetic heads must be shortened accordingly. There is a need.

However, when two magnetic heads are placed adjacent to each other, leakage magnetic flux from one magnetic head in a recording state causes current to flow through the winding of the other magnetic head, which is not in a recording state, resulting in crosstalk.

Also, during playback, the magnetic head that is not in the playback operation state causes the magnetic flux taken in from the corresponding track of the magnetic disk to leak into the core of the magnetic head that is in the playback operation and is disposed adjacent to the magnetic head. Crosstalk occurs in the magnetic head inside. This crosstalk that occurs during recording and reproduction causes a decrease in S/N and synchronization, leading to deterioration in image quality.

In magnetic recording and reproducing devices such as electronic still cameras, when reproducing frame-recorded video signals, two magnetic heads are switched every 1/60 seconds, and the winding terminals of the magnetic heads that are not in the reproducing state are shorted (between the terminals). The impedance is approximately 10Ω or less. In this case, the reproduction crosstalk is 5 to 50% higher than when the winding terminals of the magnetic head are left open.
It was found through experiments that the increase was 10 dB. In other words, this crosstalk (not only during playback but also during recording) increases in inverse proportion to the square of the distance between the two magnetic heads, but even if the distance between the two heads is constant, for example during playback, As for Kuko talk, it was confirmed through experiments that it changes depending on the magnitude of the impedance between the winding terminals of a magnetic head that is not in a reproducing state.

[Purpose of the invention]

The present invention was made in view of these circumstances, and
It is an object of the present invention to provide a magnetic recording/reproducing device in which crosstalk is reduced without changing the distance between magnetic heads.

[Summary of the invention]

In order to achieve the above object, the present invention has a plurality of wire-wound magnetic recording/reproducing heads disposed adjacent to each other, and operates each of these heads in chronological order to record the shape of a disk being rotated. In a magnetic recording and reproducing apparatus that records a plurality of different signals on a magnetic recording medium or reproduces the signals from the magnetic recording medium, the winding terminals of the recording heads other than the selected recording head are opened during recording. The present invention is characterized in that it has means for bringing the winding terminals of the reproducing heads other than the selected reproducing head into an open state during reproduction.

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the magnetic recording and reproducing apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. First, prior to a detailed explanation of the present invention, let us first discuss the relationship between the impedance between the winding terminals of the magnetic head in a non-operating state and the amount of crosstalk in a magnetic recording/reproducing apparatus equipped with two magnetic heads.
This will be explained based on FIGS. 5 to 5. FIG. 3 shows the configuration of a measurement circuit that measures the amount of crosstalk during playback of frame-recorded video signals. In the figure, 100A and 100B are magnetic heads that reproduce video signals from predetermined tracks of the magnetic disk 50, but in this measurement circuit, only the magnetic head 100A reproduces a single frequency signal corresponding to the video signal. It has become. A variable resistor VR is connected between both ends of the winding of the magnetic head 100B, and the impedance between the winding terminals is set from 0 to (
(a) It is possible to vary within the range of (b).

Also, VC is a peaking capacitor for high frequency compensation,
102 is a playback preamplifier, 104 is a preamplifier 102
This is a spectrum analyzer that analyzes the frequency spectrum of the signal output from the spectral analyzer.

Here, the magnetic head i o O, A, 1. A single frequency signal of 7.5 MHz is recorded on the track to be reproduced from the magnetic head 100B', and a signal of a single frequency of 7.5 MHz is recorded on the track to be reproduced from the magnetic head 100B'. In this measurement circuit, since the impedance between the winding terminals of the magnetic head 100B is not changed by the variable resistor VR, the magnetic head 100B is
i:1 to Jl from 0A via the playback preamplifier 102
By observing the frequency spectrum of No. 13, the crosstalk extent Q with respect to the impedance between the winding terminals of the magnetic head in a non-reproducing state is measured. cross 1-ri i
As shown in FIG. 4, Q is originally determined by the magnetic head 100A in the spectrum reproduced by the magnetic head 100A.
For the 7.5MHz No. 18 level that should be reproduced,
The recording level of each signal of 7MHz and 7.5MHz is the same. ).

The above measurement results are shown in FIG. -Finally Kukostalk I
It is said that it is preferable for Q to be -40 dB or less, and as is clear from the figure, the crosstalk ■ should be -40 dB or less.
To achieve the following, it is necessary to make the impedance between the winding terminals of the magnetic head in the non-reproducing state approximately 10Ω or more.

The reason why the amount of crosstalk decreases as the impedance between the winding terminals of the magnetic head in the non-reproducing state increases is considered to be due to the following reason G. That is, in FIG. 3, a signal current i flows through the winding of the magnetic head 100B due to the magnetic flux detected from the corresponding track of the magnetic disk 50 by the magnetic head 100B. This current i generates (ff flux ψ), which appears as crosstalk. Therefore, as the impedance Z between the winding terminals of the magnetic head 100B in the non-reproducing state increases, the current i flows into the winding of the head 100B. This is because the current 1 also becomes smaller, and as a result, the magnetic flux ψ, which causes Kukostalk, also becomes smaller.

Note that the impedance between the winding terminals of the magnetic head required to reduce crosstalk during frame playback is 1.
Although 0Ω or more is required, the same applies to frame recording.

Next, the configuration of an embodiment of a magnetic recording/reproducing apparatus according to the present invention is shown in FIG. In the figure, the magnetic recording/reproducing head IOA
, IOB are respectively connected to the pulse generating circuit 18 via a transistor Q1, a resistor R2 or a transistor Q2, a resistor R3, and an inharc I6. The bases of transistors Q1 and Q2 are connected to resistors R1 and R, respectively.
4 and the emitter is connected via a transformer 12.14 to the movable contact side of a changeover switch 18.20.

Further, the fixed contact a of the changeover switch 18.20 is connected to a recording amplifier 22.26, and the fixed contact is connected to a reproduction amplifier 24.
28 are connected to each other.

The pulse generating circuit 17 outputs 1 as shown in FIG. 2(a).
A pulse signal that changes to high level or low level is output every vertical scanning period (this is expressed as 1). The transistor Q1 is connected to the output of the pulse generator circuit 1, and the transistor Q2 is connected to the inverter 1 shown in FIG. 2(b).
The output of transistor Q1 is switched to a state opposite to that of transistor Q1.

The impedance of each circuit element is adjusted so that when the transistors Ql and Q2 are switched to the OFF state, the impedance between the winding terminals of the magnetic heads IOA and IOB has a crosstalk of less than 40 dB, that is, a value sufficiently larger than 10 Ω. It goes without saying that a constant is selected.

In the above configuration, during frame recording, the changeover switch 1 is controlled by a control signal output from a control circuit (not shown).
8.20 is switched to the contact a side. At the same time, the pulse signal outputted from the pulse generation circuit 18 via the resistor R2 causes the transistor Q1 to be in the ON state (
For example, at T1) in FIG. 2, the output voltage from the recording amplifier 22 is stepped up by the transformer 12, and the transistor Q
A predetermined recording current is applied to both ends of the winding of the magnetic head IOA through the coil 1, and a predetermined recording current flows through the winding, so that, for example, an odd field video signal is recorded on the corresponding trunk of a magnetic disk (not shown). .

Next, in period T2 (Fig. 3), transistor Q1 is OFF.
Since the transistor Q2 is in the F state and the transistor Q2 is in the ON state, the output voltage of the recording amplifier 26 is boosted by the transformer 14, and then the output voltage of the recording amplifier 26 is transferred to the magnetic head IOH via the transistor Q2.
is applied to the winding, a predetermined recording current flows through the winding,
For example, an even field video signal is recorded on the corresponding track in the same way as described above. In this way, frame recording is performed on two trunks of the magnetic disk.

On the other hand, during frame playback, the changeover switches 18 and 20 are switched to the contact side by a control signal from a control circuit (not shown), and the magnetic heads IOA and IOB are connected as in the case of recording.
Odd field video signals and even field video signals are alternately reproduced every 1v, thereby performing frame reproduction.

〔Effect of the invention〕

As explained above, in the present invention, multiple types of signals can be recorded or recorded on a rotating magnetic recording medium or a magnetic tape medium by operating a plurality of adjacently arranged wire-wound magnetic recording/reproducing heads in time series. In a magnetic recording/reproducing device that performs reproduction, the winding terminals of magnetic heads other than those in operation during recording or reproduction are configured to be in an open state, so that when recording/reproducing between adjacent magnetic heads, Crosstalk can be reduced compared to the conventional method.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a main part of an embodiment of the magnetic recording/reproducing apparatus according to the present invention, FIG. 2 is a timing chart showing the operation of the magnetic recording/reproducing apparatus in FIG. 1, and FIG. Circuit diagram showing a measurement circuit for measuring the amount of talk, No. 4
The figure is an explanatory diagram showing the amount of crosstalk between two adjacent magnetic heads, and FIG. FIG. 10A, IOB...magnetic recording/reproducing head, Ql, Q
2...Transistor, 12.14...Transformer,
17... Pulse generation circuit, 18.20... Changeover switch, 22.26... Recording amplifier, 24.28
...Reproduction amplifier.

Claims (2)

[Claims] (1) It has a plurality of wire-wound magnetic recording/reproducing heads arranged adjacently, and by operating each of these heads in chronological order, it is possible to record a plurality of different signals on a magnetic recording medium or to record the magnetic recording medium. In a magnetic recording and reproducing apparatus for reproducing the signal from a recording medium, there is provided a means for opening the winding terminals of the recording heads other than the selected recording head during recording, and means for opening the winding terminals of the recording heads other than the selected recording head during reproducing. 1. A magnetic recording and reproducing apparatus comprising: means for opening the winding terminals of the reproducing head. (2) The magnetic recording and reproducing apparatus according to claim 1, wherein a step-up transformer is provided between the winding of each head and a recording system or reproducing system amplifier.