JPH03113756A - Magneto-optical recording and reproducing head - Google Patents

Abstract

PURPOSE:To reduce the size and weight of the small magneto-optical recording and reproducing head and to save the electric power thereof by constituting the head in such a manner that a coil for external magnetic fields adopted to impress the external magnetic fields to an magneto-optical recording medium can be moved integrally with an objective lens. CONSTITUTION:The coil 2 for external magnetic fields is provided at the position on the immediate outer side of the objective lens 1 of a lens barrel 3 mounted with the objective lens 1. The concentrical impression of the external magnetic fields to the position where the lens 1 focuses is possible in this way. The lens barrel 3 is supported to a movable part 4 of a focus control driving mechanism. The coil 2 is integrated with the lens 1 by such constitution and is the objective of focus servo. The magneto-optical recording and reproducing head which is controlled to always the constant distance with the recording surface of the recording carrier is obtd. The magneto-optical recording and reproducing head which is small in size and weight and consumes less electric power is obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] Regarding a magneto-optical recording and reproducing head that integrates an optical head for recording and reproducing information on a magneto-optical recording medium and a coil for applying an external magnetic field during recording, In particular, the present invention relates to a magneto-optical recording/reproducing head which is miniaturized by reducing the current required to apply an external magnetic field to reduce heat generation.

[Summary of the invention]

The present invention enables the external magnetic field coil for applying an external magnetic field to the magneto-optical recording medium to be movable together with the objective lens of the optical head, so that the external magnetic field coil is also subject to focus servo and the distance from the recording surface is increased. This is a magneto-optical recording/reproducing head in which the angle is always controlled to be constant. The current for the external magnetic field is small, making it suitable for rotating heads.

[Conventional technology]

In magneto-optical recording, which is attracting attention as a rewritable recording method, a magnetic field is applied from outside the record carrier, and laser light is irradiated to heat the recording medium to record in the form of changes in the direction of the magnetic field within the recording medium. It is reproduced by irradiating weak laser light and detecting the difference in rotation angle of the reflected light. For this purpose, a coil for applying an external magnetic field (an external magnetic field coil) and an optical helad are used. The optical head is composed of a semiconductor laser, a light-receiving element, an objective lens, and other elements, and is held by a drive mechanism that drives the entire optical head mechanism along a plane parallel to the recording surface in order to track the recording track. It also includes a focus control drive mechanism that drives the objective lens in a direction perpendicular to the recording surface.

Conventionally, the external magnetic field coil was often installed at a position that sandwiched the record carrier and faced the objective lens of the optical head (
Figure 5). This is to enable efficient recording by making the position of high magnetic flux density equal to the position to be recorded by the optical head.

However, in a configuration in which the external magnetic field coil is arranged on the opposite side of the record carrier with respect to the objective lens, if the recording surface of the record carrier moves relatively (warpage in the case of a disk-shaped carrier, warpage in the case of a tape-shaped carrier) (surface runout, etc.) has a problem in that the portion of the magnetic field generated by the external magnetic field coil with the highest magnetic flux density deviates from the position to be recorded (recording pit). To compensate for this, the current flowing through the external magnetic field coil has increased, and the heat generated from the external magnetic field coil has also increased. In addition, when the record carrier is tape-shaped, it is advantageous to use a rotating head type that has extensive experience in magnetic recording, but in a configuration where an external magnetic field coil is provided on the opposite side of the record carrier, a rotating head type is used. This was extremely difficult. Furthermore, when the record carrier is in the form of a disk, it may be desirable to be able to record on both sides, but this poses a problem in that both the loading and unloading of the disk and the head mechanism become complicated. Accordingly, the optical head and the external magnetic field coil can be integrally formed on the same side of the recording carrier surface (FIG. 6).

Furthermore, according to the technique disclosed in Japanese Utility Model Application Laid-Open No. 57-91114, it is said that an external magnetic field can be uniformly applied to a disk-shaped record carrier.

However, the technique disclosed in Utility Model Application Publication No. 57-91114 also has unresolved practical problems.

First, in Utility Model Application No. 57-91114, in order to obtain a uniform external magnetic field by controlling the leakage magnetic flux of the permanent magnet that serves as the focus drive stator, the external magnetic field coil is used as a focus control drive mechanism. It is installed on the fixed side of the
Since the servo in the direction perpendicular to the recording surface is not effective, it is still necessary to generate a large magnetic flux using a large current in order to obtain sufficient magnetic flux density even when the recording surface is pretended.

Second, since the external magnetic field coil is provided on the stator side of the focus control drive mechanism, the coil needs to be extremely large in size compared to the size of the recording bit that is focused by the objective lens. However, there were problems that restricted miniaturization.

Thirdly, as a result of the problems described in the first and second points, a magneto-optical recording head that integrates an optical head and an external magnetic field head inevitably becomes larger, such as a rotary head. However, there was a problem in that it could not be applied to cases where it was required to be extremely small and lightweight.

[Problem to be solved by the invention]

The present invention solves the problems of the prior art, integrates an optical head and an external magnetic field coil, and provides an optical head that is small and lightweight and can be applied to tape-shaped record carriers to form a suitable rotary head. The objective is to obtain a magnetic recording/reproducing head.

[Means to solve the problem]

In the present invention, in a magneto-optical recording/reproducing head equipped with a focus control drive mechanism in which an objective lens is movable in the optical axis direction of the objective lens, an external magnetic field coil for applying an external magnetic field to a magneto-optical recording medium is provided. The magneto-optical recording/reproducing head is characterized in that it is configured to be movable together with the objective lens.

[Function] In the present invention, the external magnetic field coil is subjected to focus servo together with the objective lens, and the distance from the recording surface of the record carrier is always controlled to be constant.

As a result, the servo is applied to the deflection and tracking deviation of the recording surface, and the magnetic flux can be concentrated on the target recording bit. Therefore, the external magnetic field coil is small and the magnetic field strength necessary for recording can be achieved by applying a small current. Obtainable.

Therefore, the heat generation from the external magnetic field coil is small, and the increase in volume and weight due to adding the external magnetic field coil to the objective lens can be made small.

〔Example〕

A first embodiment of the present invention will be described with reference to FIG.

An external magnetic field coil 2 is located just outside the objective lens 1 of a lens barrel 3 to which the objective lens 1 is attached (for example, in a holder for attaching the objective lens 1). This results in
The external magnetic field can be applied in a concentrated manner to the position where the objective lens 1 is focused. The lens barrel 3 is supported by a movable part 4 of a focus control drive mechanism. The structure of the movable part 4 and the fixed part 5 of the focus control drive mechanism is simplified when one is a coil and the other is a permanent magnet. Note that the opening of the magnetic path of the focus control drive mechanism is located on the side far from the recording medium, and a magnetic shield is provided to prevent leakage of magnetic flux to the recording medium.

In the first embodiment shown in FIG. 1, the objective lens 1 is arranged at the center of the focus control drive mechanism, but a support mechanism for movable parts such as a damper (not shown) is required. On the other hand, the second
In the second embodiment shown in the figure, a shaft 6 supporting a movable portion 4 is provided at the center of the drive of the focus control drive mechanism, and the objective lens 1 is placed apart from the shaft 6.

Although the configuration of either the first embodiment or the second embodiment can be chosen arbitrarily, the key point of the present invention is to move integrally with the objective lens 1 disposed on the movable part 4 of the focus control drive mechanism. This is where the external magnetic field coil 2 is placed.

FIG. 3 shows an application example of the present invention, in which the present invention is applied to a rotary head for recording and reproducing by winding a tape-shaped record carrier around a rotary drum.

Since the external magnetic field coil 2 is integrated with the objective lens 1, it can be attached to a rotating drum and rotated together with the optical system constituting the optical head.

FIG. 4 shows another example of application of the present invention, which is a device capable of performing magneto-optical recording and reproduction on an endless tape-shaped record carrier.

Both FIGS. 3 and 4 can be easily realized by focusing the external magnetic field coil 2 at the same time as the objective lens 1 in order to cope with surface wobbling of the tape-shaped record carrier.

〔Effect of the invention〕

By implementing the present invention, the external magnetic field coil is integrated with the objective lens, becomes the target of focus servo, and magneto-optical recording/reproduction in which the distance from the recording surface of the record carrier is always controlled to be constant is obtained. It will be done.

As a result, it is possible to obtain a magneto-optical recording/reproducing head that is small, lightweight, and power-saving, and also to obtain a rotary head suitable for application to a tape-shaped record carrier.
It can contribute to the realization of TR (video tape recorder).

[Brief explanation of drawings]

Figure 1 is a conceptual diagram of a first embodiment of the present invention, Figure 2 is a conceptual diagram of a second embodiment of the present invention, Figure 3 is an application example of the present invention, and Figure 4 is a conceptual diagram of a second embodiment of the present invention. This is another application example. FIG. 5 is a conceptual diagram of a conventional example, and FIG. 6 is a sectional view of Utility Model Laid-Open No. 57-91114. 1-----1...----1 Objective lens 2
・−・−External magnetic field coil 3 Lens barrel 4・・−・−・・−1−−Movable part of focus control drive mechanism 5−−−−−−−−−−−・−Focus control Fixed part of the drive mechanism Fig. 1 1 Objective lens 2 Fig. 2 Illustration of the top-down features of the present invention Fig. 2 Examples of the use of this book

Claims (1)

[Claims] A magneto-optical recording/reproducing head equipped with a focus control drive mechanism that moves an objective lens in the optical axis direction of the objective lens, comprising an external magnetic field coil for applying an external magnetic field to a magneto-optical recording medium. A magneto-optical recording/reproducing head, characterized in that it is configured to be movable together with the objective lens.