JPS62150513A - Multi-channel magnetic head - Google Patents

Abstract

PURPOSE:To prevent crosstalk by providing plural piezoelectric elements holding each magnetic head to a normal position and displacing the head from its normal position independently due to deformation. CONSTITUTION:A magnetic head 2A of a channel A and a magnetic head 2B of a channel B are fitted to a common base 3 by bimorph plates 12A, 12B respectively. The bimorph plates 12A, 12B are formed by laminating two piezoelectric elements 13, 14 and three electrodes 15-17 alternately, and the piezoelectric elements 13, 14 are expanded or contracted by the impression of a voltage. Thus, through the operation of the piezoelectric elements, only an optional magnetic head to be used for the recording or reproduction is held at the normal position and other magnetic heads are displaced from the normal position. Thus, the inconvenience such as the provision of crosstalk to other channel or the reception of crosstalk from other channel is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to the structure of a multi-channel magnetic head and is intended to prevent crosstalk.

<Prior art> In a conventional multi-channel magnetic head, the multiple magnetic heads that make up the head are not able to contact the magnetic recording medium independently, and the whole magnetic head is always connected to the magnetic recording medium together. It has a contact structure.

<Problems to be Solved by the Invention> As described above, when a plurality of magnetic heads come into contact with a magnetic recording medium together, crosstalk problems occur for the following reasons.

Now, let us consider a two-channel magnetic recording/reproducing apparatus such as an electronic still camera using a disk-shaped magnetic sheet as shown in FIG. In the figure, 101 is a two-channel magnetic head, which has an A-channel magnetic head 102A and a B-channel magnetic head 102B, and these two magnetic heads 102A and 102B are fixed to a common base 103. . 104 is a magnetic recording medium, 104AI is an A channel track, and 104B is a B channel track. 105A1. tA channel recording selection switch, channel recording selection switch from 105Bl, IC16A1. Recording amplifier for tA channel, 106
B is a recording amplifier for B channel; 107A is a recording/playback switch for A channel; 107B is a recording/playback switch for B channel; 108A is a playback amplifier for A channel; 109A is a switch for selecting A channel playback; 109B1 ．． This is a switch for selecting tB channel reproduction.

For example, when recording on track 104A of channel A, switch 105A is turned on and switch 107 is turned on.
Insert both A and 107B into the recording side (black circle side). The other switches 105B, 109A and 1119B are turned off. As a result, the signal from the input terminal 110 passes through the recording amplifier 106A to the A channel magnetic head 1.
02A and recorded on track 104A. However, since there is a slight magnetic coupling between the two magnetic heads 102A and 10213, magnetic flux leaks from the A-channel magnetic head 102A attempting to record to the adjacent B-channel magnetic head 102B.

In this case, since the magnetic head 102B is also in contact with the magnetic recording medium 104, recording is also performed on the B channel track 104B, which is not the recording target. That is,
Crosstalk occurs.

On the other hand, when reproducing from track 104B of the B channel, for example, switch 109B is turned on, and both switches 107A and 107B are turned to the reproduction side (white circle side). The other switches 105A, 105B and 109A are turned off. As a result, the signal from the B channel magnetic head 102B is amplified by the reproduction amplifier 108B,
It is output to terminal 111. However, since the magnetic head 102A of the A channel is also in contact with the magnetic recording medium 104, the signal of the track 104A of the A channel is induced in this magnetic head 102A, and the resulting magnetic flux is
There is leakage from the magnetic head 102 of the channel to the magnetic head 102B of the adjacent B channel. Therefore, the A channel signal, which is not to be reproduced, mixes into the B channel signal. That is, crosstalk occurs.

An object of the present invention is to provide a multichannel magnetic head that can prevent the above-mentioned crosstalk.

A multi-channel magnetic head according to the present invention that achieves the above object includes a plurality of magnetic heads, a common base for the plurality of magnetic heads, and a base end on each of the bases. a plurality of piezoelectric elements each having a magnetic head attached to its tip end, each of which holds each magnetic head in its normal position, and which independently displaces each magnetic head from its normal position by deformation; A piezoelectric element is provided.

Here, the piezoelectric element may be used to displace the magnetic head so that the gap is separated from the magnetic recording medium, or the piezoelectric element may be displaced so that the azimuth changes while the gear is in contact with the magnetic recording medium.

With the above-mentioned configuration, only the desired magnetic head to be used for recording or reproduction can be held at the normal position by the action of the piezoelectric element, and all other magnetic heads can be displaced from their normal positions. can. Since a magnetic head displaced from its normal position has a large spacing loss or azimuth loss, no crosstalk occurs during recording or reproduction.

Embodiments The present invention will be described in detail below with reference to FIGS. 1 to 13.

FIG. 1 is a perspective view of a two-channel magnetic head that utilizes spacing loss in an embodiment of the present invention. FIG. 11 is a circuit diagram of an example of a two-channel magnetic recording/reproducing device, and FIGS. 12 and 13 are timing charts illustrating its operation.

First, in FIG. 1, the A channel magnetic head 2A
and a B channel magnetic head 2B are attached to a common base 3 by bimorph plates 12A and 12B, respectively.

The two bimorph plates 12A and 12B are fixed to the base 3 so that the two bimorph plates 12A and 12B face each other parallel to each other, have their tips facing the magnetic recording medium 4, and are deformed in a plane perpendicular to the longitudinal direction of the track. has been done. Further, magnetic heads 2A, 2 are provided at the tips of each bimorph plate 12A, 12B.
B is fixed one by one so that the gap faces the magnetic recording medium 4. In FIG. 1, 12A-1, 12A-2 and 12A-3 are lead wires of the bimorph board 12A, and 12B-1, 12B-2 and 12B-3 are lead wires of the bimorph board 12B. Bimorph board 1 of this example
2A and 12B, as illustrated in FIG. 2, are two piezoelectric elements 13, 14 and three electrodes 15, 16, 17 stacked alternately. A piezoelectric element expands or contracts by applying a voltage. Therefore, the bimorph plate 12A in FIG.
(12B) changes shape as shown in Figure 3 ta), (bl, tel) depending on how voltage is applied between the electrodes.
=0), the same figure (bl is "'IA"-E2A>0(E+
e=-E211>O), the same figure (cl is E, A=-E2
Examples of shapes in the case of A<O (E, a=-E2.<O) are shown.

Here, E, A, and E4 are assumed to be the voltages of one outer electrode 15 with reference to the central common electrode 16, and E2A and E28 are assumed to be the voltages of the common electrode 16 with respect to the other outer electrode 17. . As a result, the two-channel magnetic head 1 shown in FIG.

As shown in (b) and (e), two magnetic heads 2A.

The position of 2B can be changed freely. However, FIG.
This is a case where IA=E2A=0 and EIll=E2B=0, and the two magnetic heads 2A and 2B are both held at the normal position where the gap contacts each track 4A and 4B of A and B of the magnetic recording medium 4. (I'm sorry). Figure 4 (b
l is EI A = E2A = o and E, 6 = -E
This is the case of 2°-+0, and the magnetic head 2 of the A channel
Only A is held in the correct position relative to track 4A,
The gap between the B channel magnetic head 2B is bimorph plate 1:! Due to the curvature of B, it is slightly separated from track 4B. In the case of Fig. 4 fbl, when recording on track 4A by flowing a recording current to the magnetic head 2A of the A channel, even if magnetic flux leaks to the magnetic head 2B of the B channel, there is a gap between this magnetic head 2B and track 4B. Since a large spacing loss has occurred in , recording to track 4)1 is not performed. In addition, in the case of FIG. 4 (bl), when the A channel magnetic head 2A reproduces the signal from track 4A, the B channel magnetic head 2B does not reproduce the signal from track 4B due to spacing loss, so the signal from track 4B is It does not mix into the output of the A channel magnetic head 2A.FIG. 4 fc) is the same. =-E2
Go to A.

In addition, this is the case when E16=E2B"", as shown in Fig. 4 (bl
Contrary to the case of , only the B channel magnetic head 2B is held at the normal position with respect to the track 4B, and the gap between the two A channel magnetic heads is the bimorph plate 12A.
It is slightly away from track 4A due to the curvature of. Therefore, when a recording current is applied to the magnetic head 2B of the B channel to record on the track 4B, a large spacing loss occurs between the two magnetic heads of the A channel and the track 4, so the magnetic head Even if magnetic flux leaks to track 2A, no recording is performed on track 4A. Also, when the B channel magnetic head 2B reproduces the signal from track 4B, the A channel magnetic head 2A does not reproduce the signal from track 4A due to spacing loss, so the signal from track 4A is output from the B channel magnetic head 2B. There is no chance of contamination. Note that if the gap of the magnetic head is separated from the track by 1 μm or more, sufficient spacing loss can be obtained to prevent crosstalk.

Next, using the azimuth loss, the example is shown in Figures 5 and 6.
This will be explained with reference to the figures. In the two-channel magnetic head 1 of this embodiment, the two bimorph plates 12A and 12B face each other parallel to each other, have their tips oriented parallel to the magnetic recording medium 4, and are deformed in a plane parallel to the magnetic recording medium 4. As shown, each base end portion is fixed to the base 3. Each bimorph plate 12A.

One magnetic head 2A and one magnetic head 2B are fixed to the tip of the magnetic head 12B so that the gap faces the magnetic recording medium 4. Bimorph board 12A.

12B is the one explained with reference to FIGS. 2 and 3. In the two-channel magnetic head 1 shown in FIG. 5, the two-channel magnetic head 1 shown in FIG.
al, fbl, the positions of the two magnetic heads 2A, 2B can be freely changed as shown in (e).

However, Fig. 6 (al, (b)).

fe) is a plan view of the magnetic head. Figure 6 (al is
This is the case where E = E = O and E = E = O, and 1^ 2^ IB
Both of the two magnetic heads 2A and 2B are held at regular positions with a predetermined azimuth. In the figure, G indicates a gap. Figure 6(b) (Yo, E =
This is the case when E = O and E = -E -O, and 1^
2^ 111
Only the magnetic head 28 of the 28A channel is held in the normal azimuth with respect to the 1-rank 4A, and the azimuth of the B channel magnetic head 2B is deviated from the normal direction due to the curvature of the bimorph plate 12B. In the case of FIG. 6(b), when a recording current is applied to the magnetic head 2A of the A channel to perform recording on the track 4A, even if magnetic flux leaks to the magnetic head 2B of the B channel, the magnetic head 2B and the track 4B Since there is an anomalous difference between the two, no disturbing recording is performed on track 4B. In addition, FIG. 6 (in case of BL, A channel magnetic head 2A)
When reproducing the signal from the track 4A, the B channel magnetic head 2B does not reproduce the track 4B signal due to azimuth loss, so that the signal from the rack 4B does not mix into the output of the A channel magnetic head 2A. Figure 6 (cl is E1A=-E2A(=0 and TSE1B=E2
This is the case when 6=O, and as shown in Fig. 6 (contrary to the case of bl, B
Only the magnetic head 2B of the channel is held in the normal azimuth with respect to the track 4B, and the azimuth of the magnetic head 2A of the A channel is deviated from the normal direction due to the curvature of the bimorph plate 12A. Therefore, when recording or reproducing the track 4B with the B channel magnetic head 2B, no crosstalk occurs due to the azimuth loss of the A channel magnetic head 2A.

Next, Fig. 7 shows another example using spacing loss.
This will be explained with reference to FIG. In the two-channel magnetic head 1 of this embodiment, as shown in FIG. 7, there are two bimorph plates 12A.

12B are deviated perpendicularly to the track longitudinal direction and face parallel to each other, and the leading end faces the magnetic recording medium 4, and is deformed in a plane perpendicular to the magnetic recording medium 4 with a track longitudinal force +t'b. , each base end portion is fixed to the base 3. At the tip of each bimorph plate 12A, 12B, magnetic/\rad 2A, 2B
are fixed one by one so that the gap faces the magnetic recording medium 4. In the two-channel magnetic head 1 shown in FIG. 7, when the bimorph plate 12B, for example, is bent, the gap of the magnetic head 2B separates from the magnetic recording medium 4, as shown in FIG.

Still another example utilizing spacing loss is shown in Fig. 9.
This will be explained with reference to FIG. In the two-channel magnetic head 1 of this embodiment, as shown in FIG. 9, there are two bimorph plates 12A.

The magnetic recording media 12B are arranged horizontally parallel to the magnetic recording medium 4, and their base ends are fixed to the base 3 so as to be deformed along the track longitudinal direction and in a plane perpendicular to the magnetic recording medium 4. One magnetic head 2A, 2B is fixed to the tip of each bimorph plate 12A, 12B with the gap facing the magnetic recording medium 4.

In the two-channel magnetic head 1 shown in FIG. 9, when the bimorph plate 12A, for example, is bent, the gap of the magnetic head 2A separates from the magnetic recording medium 4 as shown in FIG.

Naturally, the control of the bimorph plates 12A and 12B in the two-channel magnetic head 1 of each of the embodiments described above must be performed in synchronization with channel switching in the magnetic recording or reproducing apparatus. A specific example of this will be explained with reference to FIGS. 11 to 13, in which a video signal for one frame is recorded and reproduced in a so-called electronic still camera using a disk-shaped magnetic sheet. In Figure 11,
1 is a two-channel magnetic head, 2A is an A-channel magnetic head, 2B is a B-channel magnetic head, and 5A is an A-channel magnetic head.
Channel recording selection switch, 5B is B channel recording selection switch, 6A is A channel recording amplifier,
6B is a recording amplifier for B channel, 7AlfA channel recording/playback selection switch, 7BlfB channel recording/playback selection switch, 8A is a playback amplifier for A channel, 8B is a playback amplifier for B channel, 9A is a switch for A channel playback selection. , 9B is a B channel playback selection switch, 10 is a terminal for inputting signals from the video camera, 11 is an output terminal, 12A is a bimorph board that holds the A channel magnetic head 2A, and 12B is a B channel magnetic head 2B. Bimorph plate holding 18A
is the drive circuit for the A channel bimorph board 12A, 18
B is a drive circuit for the B channel bimorph board 12B, 1
9A is a control switch for the A channel bimorph drive circuit 18A, 19B is a control switch for the B channel bimorph drive circuit 18B, 20 is an input terminal for recording command pulses, 21 is an input terminal for recording track switching pulses, 22
is an input terminal for the reproduction L/rack switching pulse.

In the bimorph drive circuit, the emitter of the NPN transistor 23 and the PNP! - the emitter of the transistor 24 is connected to the ground, and the collector of the transistor 23 is connected to the positive terminal (G) of the DC power supply through the resistor 25;
The collector of the transistor 24 is connected through a low current 26 to the negative terminal H of the DC power supply. A control pulse 30 obtained by inverting the inverter 27 and the inverter 29 is applied to the base of the transistor 23 . 31 is a base bias resistor. Furthermore, the common electrode 16 at the center of the bimorph
is grounded, one outer electrode 15 is connected to the active terminal of a potentiometer 32 connected between the collector of transistor 23 and ground, and the other outer electrode 17 is connected to a potentiometer connected between the collector of transistor 24 and ground. 33 sliding terminal. Potentiometers 32 and 33 are for voltage adjustment, and one outer electrode 1
A positive voltage is applied to the electrode 5, and a negative voltage is applied to the other outer electrode 17, but the absolute values of the voltages are made equal.

Next, the operation of the circuit shown in FIG. 11 will be explained with reference to FIGS. 12 and 13. First, in the case of recording, the first
A recording command pulse 34 is inputted as shown in ta+ in FIG. 2, and a track switching pulse 35 is inputted to the input terminal 21 as shown in FIG. 12(b). The pulse 34 has a vertical scanning period (1v
) becomes high level for a period of 2v, and from this 1
After a delay of v, the pulse 35 becomes high level for a period of 1v. These pulses 34 and 35 are input to the logic operation circuit 36, and the output pulses 37 and 35 shown in FIG.
, 38, the two recording track selection switches 5A
.

5B is turned on alternately for 1V periods as shown in FIG. control switch 19A, 19
Both B are input to the recording side (black circle side in FIG. 11) as shown in FIG. 12(g). As a result, while the switch 5A is turned on and recording of the A channel is performed, in the A channel bimorph drive circuit 18A, the input of the inverter 27 is at a low level, and the two transistors 2
3 and 24 are both turned on, and the voltage applied to the bimorph plate 12A of the A channel is as shown in FIG.
(As i+<E1A=E2A=0, the magnetic spatula F2
A is held in its normal position. During this time, in the B channel bimorph fishing circuit 18B, the input of the inverter 27 becomes high level, both transistors 23 and 24 are turned off, and the B channel bimorph board 12B
The voltage applied to E, , = -E2. .about.0, and the magnetic head 2B is shifted from its normal position.

On the other hand, when the switch 5B is turned on], while the B channel is being recorded, the voltage applied to the B channel bimorph plate 12B is EIB as shown in FIG. 12 (jl, (k)).
=E211 =0, the magnetic head 2B is held at the normal position, and the A channel bimorph plate 12A is
The voltage applied to the magnetic head 2A becomes E1A=-E2A←O, and the magnetic head 2A is shifted from its normal position. .

Next, in the case of reproduction, a track switching pulse 39 is input to the input terminal 22 as shown in FIG.
9 becomes high level and low level as many times as necessary per 1v period. This pulse 39 is input to the logic circuit 40,
Its output pulses 41, 4 shown in FIG. 13 (bl, (cl)
2, the two playback track selection switches 9A,
As shown in FIGS. 9(d) and 9(e), 9B alternately turns on and off for each IV period. While the track switching pulse 39 for reproduction is being applied, as shown in FIG. 13(f), 2
The two recording/reproduction changeover switches 7A and 7B and the two bimorph drive circuit control switches 19A and 19B are all turned on to the reproduction side (white circle side in FIG. 11). As a result, 1. While the switch 9A is on and the A channel is being reproduced, the input of the inverter 27 is at a low level in the A channel bimorph drive circuit 18A, and the voltage applied to the A channel bimorph board 12A is at the 13th level. As shown in FIGS. (g) and (h), <E=E=O, and the magnetic head 2A is held at the normal position. During this time, in the B channel bimorph drive circuit 18B, the input of the inverter 27 becomes high level, both transistors 23 and 24 are turned off, and the voltage applied to the B channel bimorph board 12B is EIB''-E2B.
”, and the magnetic head 2B is shifted from its normal position. Conversely, while the switch 5B is turned on and the B channel is being reproduced, the voltage applied to the B channel bimorph plate 12B is as shown in FIG. i), E as in (j)
=E2. =O, and the magnetic head 2B is held at the normal position, and the Sarel voltage applied to the bimorph plate 12A of A channel becomes E, and A=-E2A+0, and the magnetic head 2A is shifted from the normal position. It will be done.

Although each of the above embodiments concerns a two-channel magnetic head, a general multi-channel magnetic head may have the same structure as the embodiments. Furthermore, although the above embodiments relate to an electronic still camera using a magnetic disk, it can be used regardless of the shape of the recording medium (tape, sheet, etc.) or the type of recorded or reproduced signal (audio signal, data signal, etc.). ), the present invention can be applied.

<Effects of the Invention> According to the present invention, when recording or reproducing a channel using any one of the multi-channel magnetic heads, other magnetic heads can be shifted from their normal positions. This eliminates problems such as giving crosstalk to other channels or receiving crosstalk from other channels.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a two-channel magnetic head according to an embodiment of the present invention, Fig. 2 is a perspective view of a bimorph plate, Fig. 3 is an explanatory diagram of changes in the shape of the bimorph plate, and Fig. 4 is a diagram similar to that of Fig. 1. FIG. 5 is a perspective view of a two-channel magnetic head according to another embodiment, and FIG. 6 is an explanatory diagram showing the operation of the two-channel magnetic head shown in FIG. FIG. 7 is a perspective view of a two-channel magnetic head according to another embodiment; FIG. 8 is an explanatory diagram showing its operation as viewed from the X direction in FIG. 9; FIG. 9 is a perspective view of a two-channel magnetic head according to another embodiment, FIG. 10 is an explanatory diagram showing its operation as viewed from the X direction in FIG. 9, and FIG. 11 is an embodiment of the present invention. A circuit diagram of a two-channel magnetic recording/reproducing device according to an example, FIG. 12 is a timing chart of its recording operation, FIG. 13 is a timing chart of its reproducing operation, and FIG. 14 is an explanatory diagram of the prior art. . In the drawing, 1 is a two-channel magnetic head, 2 and 2B are individual magnetic heads, 3 is a base, 4 is a magnetic disk, and 4A and 4B are!・Rack, 5A and 5B are recording track switching switches, 6A and 6B are recording amplifiers, 7A and 7B are recording /
Playback selector switch, 8A and 8B are playback amplifiers, 9A and 9
B is a playback track switching switch, 10 is a recording signal input terminal, 11 is a playback signal output terminal, 12A and 12Bl
j bimorph board, 18A and 18B are bimorph drive circuits, 19A and 19B are their control switches, 20 is an input terminal for a recording command, 21 is an input terminal for a recording track switching command, and 22 is an input terminal for a reproduction track switching command. .

Claims (1)

[Claims] A plurality of magnetic heads, a base common to the plurality of magnetic heads, and a plurality of piezoelectric elements each having a base end attached to the base and the magnetic head attached to each tip. A multi-channel magnetic head comprising a plurality of piezoelectric elements that hold each magnetic head in a normal position and independently displace each magnetic head from the normal position by deformation.