JPH01134702A - Tracking control device - Google Patents

Abstract

PURPOSE:To increase the frequency response characteristics of a tracking control system by causing a current to flow to a prescribed superconductor element selected according to the level of a tracking error signal. CONSTITUTION:The title device has superconductor elements 101-106 to be independently connected to plural output signal lines 107-112 of a decoder circuit 115 to selectively switch the output signal lines 107-112 to be supplied with the current according to the level of a tracking error signal 116. In such a case, since, by converting the selected superconductor element to a permanent conductor, valid head width positions 307 and 308 of magnetic heads 302 and 303 are made variable and a substantial tracking control can be executed, the response frequency of a track curve following control system can be sufficiently increased.

Description

[Detailed Description of the Invention] Industrial Field of Application The present invention relates to a tracking control device for a magnetic recording/reproducing device, and is capable of selectively passing current through a plurality of superconducting elements fixed to a magnetic head surface. The present invention relates to a tracking control device that performs tracking control by switching.

BACKGROUND OF THE INVENTION FIG. 5 is a diagram showing a recording magnetization locus of a magnetic recording/reproducing apparatus (hereinafter simply referred to as a VTR). In the same figure, 50
1 is a magnetic tape, and 502, 503, and 504 are recorded magnetization trajectories. 505 indicates a magnetic head, and arrow 50
Scan in the direction indicated by 6. The recording magnetization locus (recording track) should originally be recorded in a straight line on the magnetic tape, but in reality it is recorded in a curved form due to variations in mechanical precision.

FIG. 6 is a diagram showing the relative positional relationship between the curvature of the recording track and the magnetic head. In the same figure, 601 and 6
04 each indicates one recording track, 601 indicates a straight recording track, and 604 indicates a curved recording track. 602.605.606 indicates a magnetic head,
Scanning is performed in the directions shown by arrows 603 and 607, respectively.

In Figure 6a, the magnetic head can always scan on the recording track, but in Figure 6a, the magnetic head can scan on the recording track, depending on the scanning position of the magnetic head. Therefore, it is not possible to obtain a necessary and sufficient reproduction signal level. The influence of such track curvature becomes a problem when performing compatible playback in which tapes recorded on different decks are played back.

Conventionally, as a method to eliminate the influence of track bending, a magnetic head is mounted on an electro-mechanical transducer composed of a piezoelectric element, etc., and the mechanical height of the magnetic head is increased depending on the level of the tracking error signal. A method was used in which track bending control was performed by displacing the magnetic head position in a direction perpendicular to the scanning direction of the magnetic head.

Problems to be Solved by the Invention In the conventional method using a piezoelectric element, the response frequency of the track bending follow-up control system is limited by the response frequency of the piezoelectric element, and there is a problem that track bending having high frequency components cannot be followed. Ta.

SUMMARY OF THE INVENTION An object of the present invention is to provide a tracking control device that can follow track bends that have high frequency components.

Means for Solving the Problems In order to solve the above-mentioned problems, the present invention provides an output to which a current is to be supplied in accordance with the level of a tracking error signal indicating a relative positional deviation between a magnetic head and a recorded magnetization locus. It has a decoder circuit that selectively switches signal lines, and a superconductor element that is independently connected to a plurality of output signal lines of the decoder circuit, and the superconductor element is parallel to the scanning direction of the magnetic head. The selected superconductor element is transferred to a normal conductor by passing a current through the predetermined superconductor element which is arranged and fixed to the tape contact surface of the magnetic head and selected according to the level of the tracking error signal. This allows the effective head width position of the magnetic head to be varied, thereby achieving substantial tracking.

According to the present invention, with the above-described configuration, tracking control can be performed without using a movable element, so that the response frequency of the track bend follow-up control system can be made sufficiently high.

Embodiment FIG. 4 is a diagram showing the configuration of a conventional magnetic head. In the figure, 401 and 402 are magnetic cores, which are made of a magnetic material such as ferrite. 403 is a gap of the magnetic head. A voltage corresponding to a change in magnetic flux passing through the magnetic core 402 is extracted from a coil 404 wound around the magnetic core 402 .

Hereinafter, in Kikiri IS, the direction indicated by arrow 405 will be referred to as the direction of the head gap, and the width indicated by 406 will be referred to as the head width.

FIG. 1 is a diagram showing the basic structure of a magnetic head used in the present invention, and FIG. 2 is a plan view of the magnetic head shown in FIG. 1.

In FIG. 1, the diagram indicated by broken lines is the magnetic head shown in FIG. 4, and the same parts are indicated by the same symbols. 101-1
06 is a superconductor element. Each superconductor element is arranged in a direction perpendicular to the gap direction of the magnetic head, and each superconductor element is electrically insulated from each other.

Although FIG. 1 is a diagram showing the basic arrangement of superconductor elements, each superconductor element is actually attached in close contact with the head gap surface as shown in FIG. 2. To form such an element, for example, a superconducting thin film may be formed on the head gap surface by a method such as vapor deposition. 1 shown in Figure 2
0'l is a Mi conductor element, and 201 and 202 are electrode terminals for flowing a 7M current through the superconductor element.

In FIG. 1, 107 to 112 are lead wires for passing current through each superconductor element, and are connected to a decoder circuit 115. One lead wire of each superconductor element is
They are commonly connected as shown at 113. Common terminal 1
14 is given a ground potential, for example. Decoder circuit l1
5 selects an output line for supplying current according to the level of the tracking error signal supplied from the terminal 116.

For example, in the on-track state, the superconductor element 10
A current is passed through superconductor elements 3 and 104, and when mistracking occurs to one side, current is passed to superconductor elements 104 and 105, and when mistracking occurs to the other side, current is passed to superconductor elements 102 and 103.

Superconductors have diamagnetic properties due to the Meissner effect. Therefore, as shown in FIG. 1, when the head gap surface is covered with a superconductor, magnetic flux cannot pass through the magnetic cores 401 and 402, and the magnetic head does not function. On the other hand, when a current higher than the critical current value is passed through a superconductor, the superconductor transforms into a normal conductor. Utilizing this property, for example, if a current of critical current value -H is passed through the superconducting element shown at 103 and 104 to transfer it to a normal conductor, the magnetic flux on the magnetic tape will spread through the spaces shown at 103 and 104. and passes through magnetic cores 401 and 402. That is, the effective gap of the magnetic head is the length of the superconductor element in the herad gap direction indicated by 103 and 104. Therefore, by selecting the superconductor element through which current flows, the effective gap width and head gap position of the magnetic head can be varied.

FIG. 3 is a diagram showing a tracking state when such a magnetic head is used. In the figure, 301 is a recording track, and 302 and 303 are magnetic heads having the configuration shown in FIG. The magnetic head linearly scans in the direction shown by arrow 304. 305, 306, . . . indicate superconductor elements fixed on the magnetic head surface. When the magnetic head is in the position 303, the superconductor elements in the range 307 are transferred to a normal conductor, and when the magnetic head is in the position 302, the superconductor elements in the range 308 are transferred to the normal conductor. For example, the magnetic head scans the recording track substantially on-track. For this reason, the magnetic head is mounted on an electro-mechanical conversion element,
Tracking control can be performed without changing the mechanical height position of the magnetic head.

Effects of the Invention As is clear from the above explanation, according to the present invention, since tracking control can be performed purely electrically, the frequency response characteristics of the tracking control system can be improved compared to conventional methods using piezoelectric elements. Not only can the height be increased, but also reliability can be improved since there are no moving parts.

It also has the advantage of not requiring the high voltage required to drive the piezoelectric element.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a magnetic head according to an embodiment of the present invention, FIG. 2 is a plan view of the same magnetic head, and FIG. 3 is an explanatory diagram showing a tracking state when the magnetic head according to the present invention is applied. Figure 4 is a configuration diagram of a conventional magnetic head;
The figure is an explanatory diagram of the recording magnetization locus, and FIG. 6 is an explanatory diagram showing the relationship between track bending and the scanning position of the magnetic head. 101-106...Superconductor element, 301...Recording track, 302.303...Magnetic head, 305.
306...Superconductor element, 307.308...Effective head width, 401.402...Magnetic core, 403...
・Head gap, 405...Direction of head gap, 40G...Head width, 502~504.60L
604... Recording track, 505.602.605.
...Magnetic head. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 Figure 2 4θl Figure 3 30/ 4θZ 46)/

Claims (1)

[Claims] A decoder circuit that selectively switches an output signal line to which current should be supplied according to the level of a tracking error signal indicating a relative positional deviation between the magnetic head and the recording magnetization locus, and a plurality of output signals of this decoder circuit. and a superconductor element independently connected to the wire, the superconductor element having:
The selected superconductor element is arranged in parallel to the scanning direction of the magnetic head and fixed to the tape contact surface of the magnetic head, and is selected according to the level of the tracking error signal by passing a current through the predetermined superconductor element. A tracking control device characterized in that the effective head width position of a magnetic head is varied by transferring an element to a normal conductor, thereby achieving substantial tracking.