JPS6233343A - Optical system driver - Google Patents

Abstract

PURPOSE:To improve the high speed response by providing two permanent magnets as to one tracking coil. CONSTITUTION:Permanent magnets 10, 13 and 11, 12 are arranged to be opposed to parts (a, b) in parallel with a support shaft 4 of the tracking coil 5. The magnetic flux is generated respectively in opposite direction by the two permanent magnets 11, 12 in the tracking coil 5 and in flowing a current in the direction of arrow I, since the current direction in the coils (a), (b) is opposite to each other, an electromagnetic force in the same direction as the arrow F is exerted to the coil. Thus, the tracking torque of an optical system holder is doubled and the tracking sensitivity of the optical holder is increased twice.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an optical system driving device, and particularly relates to a support shaft, an optical system holder provided rotatably at least with respect to the support shaft, and an optical system drive device. The present invention relates to an optical system drive device that includes a permanent magnet that is provided on a holding body and that forms a magnetic field for a tracking coil that generates a rotational driving force with respect to the support shaft.

[Prior art]

Conventionally, this type of optical system driving device has a focus control function to drive and control the optical system in the optical axis direction, and a tracking control function to drive and control the optical system in a direction perpendicular to the optical axis direction. Hereinafter, explanation will be given by taking an objective lens driving device as an example, and FIG. 3 is a plan view and a front view of a conventional objective lens driving device.

The objective lens l is attached to an objective lens holder 2, and a focus coil 3 is wound around the objective lens holder 2. The objective lens holder 2 is slidable in the optical axis direction A of the objective lens with respect to the support shaft 4, and is rotatable in the arrow direction B. The focusing coil 5 is mounted on the focusing coil 3. One end of an elastic body (not shown) is attached to the shaft 6 (the other end is attached to the base 20), and the objective lens holder 2 is attached to the shaft 6 by the elastic force of the elastic body.
is maintained at a neutral position in the directions of arrows A and B. A focus coil 7 is fixed to a permanent magnet 8, and the permanent magnet 8 is fixed to a base 20, and a magnetic gap is formed between the base 20 and an integral opposing magnetic pole 9. By passing a current in the direction of arrow C through the focus coil 3 existing in the magnetic gap, an electromagnetic force is generated that moves the coil 3, that is, the objective lens holder 2, in the direction of arrow A according to Fleming's left hand rule. Since the permanent magnets 11 and 13 are magnetized as shown in the figure, magnetic flux leaks into the air in the direction of magnetization, and by passing current in the direction of the arrow in the nearby tiger, King coil 5, Fleming's left hand According to the law, an electromagnetic force is generated that moves the tracking coil 5, that is, the objective lens holder 2 in the direction of arrow B.

[Problem that the invention seeks to solve]

However, in the conventional objective lens driving device described above, the electromagnetic force for moving the objective lens holder 2 is not sufficient, and a larger electromagnetic force is desired for high-speed response.

[Means for solving problems]

The above problem consists of a support shaft, an optical system holder that is rotatably provided at least with respect to the support shaft, and a tracking system that is provided on the optical system holder and generates a rotational driving force with respect to the support shaft. The problem is solved by the optical system driving apparatus of the present invention, which has a permanent magnet that forms a magnetic field with respect to a coil, and is characterized in that two permanent magnets are provided for one tracking coil.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings. Note that an objective lens driving device will be explained as an example of the optical system driving device of the present invention. FIG. 1 is a plan view and a front view showing one embodiment of the objective lens driving device of the present invention. Note that explanations regarding the same parts as those in FIG. 3 will be omitted.

FIG. 2 is an explanatory diagram of the operation of the objective lens driving device.

In FIG. 1, reference numeral 10.12 indicates permanent magnets increased according to the present invention, which are magnetized in the opposite direction to the magnetization direction of permanent magnets 11.13. Permanent magnet 10.13 and 1
1.12 is arranged so as to face portions a and b of the tracking coil 5 that are parallel to the support shaft 4. If we pay attention to one of the tracking coils 5, as shown in FIG. When a current flows in the direction, the direction of the current in the coils a and pb is opposite, so an electromagnetic force in the same direction acts on one coil in the direction of arrow F. In other words, the tracking direction driving force according to the embodiment of the present invention is similar to that of the conventional one. This is twice the driving force in the tracking direction.

〔Effect of the invention〕

As described above in detail, according to the optical system drive device of the present invention, by providing two permanent magnets for one tracking coil, the driving force for the optical system holder is doubled, and Accordingly, the tracking sensitivity of the optical system holder can be doubled.

[Brief explanation of the drawing]

FIG. 1 is a plan view and a front view showing one embodiment of the objective lens driving device of the present invention. FIG. 2 is an explanatory diagram of the operation of the objective lens driving device. FIG. 3 is a plan view and a front view of a conventional objective lens driving device. 1... Objective lens, 2... Objective lens holder, 4...
...Support shaft, 5...Tracking coil, 10, 11
゜12.13...Permanent magnet.

Claims (1)

[Claims] A magnetic field is applied to a support shaft, an optical system holder that is rotatably provided at least with respect to the support shaft, and a tracking coil that is provided on the optical system holder and that generates a rotational driving force with respect to the support shaft. What is claimed is: 1. An optical system driving device having a permanent magnet formed therein, wherein two permanent magnets are provided for one tracking coil.