JPS6346903Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an optical pickup device, which is provided with a plurality of drive coils when driving a lens using electromagnetic force.

Recently, video disc players and digital audio disc players have been proposed that reproduce signals using optical pickup devices that utilize laser light. These devices generate electricity by passing an electric current through a coil placed in a magnetic field.
For example, focus control is performed by driving the objective lens.

Now, let us consider playing back a plurality of types of discs with different center hole diameters using one player. In this case, it is conceivable that the spindle shaft of the turntable on which the disk is placed has a multi-stage structure depending on the diameter of the center hole of the disk. With such a structure, the heights of the disks in the direction of the turntable axis will be different.
Now, assuming that the position of the magnet that makes up the optical pickup device is constant regardless of the position of the disk, the position of the drive system (coil, objective lens) placed in the magnetic field formed by this magnet will be: Since the disk is displaced in accordance with the height of the disk, the position of the drive system relative to the magnet is also displaced. In this case, increase the length of the coil appropriately,
Although it is possible to prevent the coil from coming out of the magnetic field at all when the coil is displaced to any position, doing so will result in poor coil usage efficiency and increase in coil impedance. There is a drawback. The present invention overcomes these drawbacks and will be described in detail below with reference to embodiments shown in the drawings.

In the figure, the shaft 1a of the turntable 1 is provided with a stepped portion, and the disk D is placed at an upper position as shown in FIG. 1 or a lower position as shown in FIG. The turntable 1 is rotationally driven by a motor 2. The optical pickup device 3 has a magnet 4 and a drive system 5. The drive system 5 includes a frame 6, an objective lens 7 attached to the frame 6, and coils 8a and 8b wound around the frame 6. Optical pickup device 3 body and magnet 4 fixed to the body
The position of is constant regardless of the mounting height of the disk D, and only the drive system 5 moves up and down.

FIG. 1 shows a state in which the drive system 5 is set in the upper position, and the coil 8b faces the magnet 4. FIG. 2 shows a state in which the drive system 5 is set in the lower position, and the coil 8a faces the magnet 4. By selectively passing current through the coil 8a or 8b located opposite the magnet 4, the objective lens 7 is driven to perform, for example, focus control.

According to the present invention described above, a plurality of coils are provided corresponding to the disks set at different heights, and the lens is driven by passing current only through the coil facing the magnet. This is convenient because the coil is used efficiently and the impedance of the coil can be reduced.

[Brief explanation of the drawing]

The drawings show the optical pickup device according to the present invention; FIG. 1 shows the disk in the upper position, and FIG. 2 shows the disk in the lower position. It is a diagram. 3 is an optical pickup device, 4 is a magnet, 7 is an objective lens, and 8a and 8b are drive coils.

Claims (1)

[Scope of utility model registration request] This is an optical pickup device configured to drive a lens by passing a current through a drive coil placed in a magnetic field. An optical pickup device that is equipped with a drive coil and has a configuration in which current is selectively applied only to the drive coil located in a magnetic field.