JPS6120659Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical head when a plurality of optical disks are used in an optical disk device.

In recent years, optical disk devices, like magnetic disk devices, have come to be used as storage devices for computers and the like. This optical disk device is
As shown in Fig. 1, a transparent resin or glass disk 1
The optical disk 3 is attached to a device and rotated, and the metal film 2 is evaporated in spots by a laser beam 4 irradiated according to a signal. Information is recorded using the spot 5, and the information is read out by detecting the spot 5 using an optical head. In order to further increase the storage capacity of such an optical disk device, a system using a plurality of optical disks has been considered. Therefore, there is a need to develop an optical head necessary for this method. The present invention was devised based on this requirement.

For this reason, the present invention provides an optical head for an optical disk device that uses at least two or more disk surfaces as information recording surfaces, and includes two focus lenses facing each of the two opposing recording surfaces; One or two focus adjustment mechanisms that support a focus lens and can adjust its focus, and a light beam from a light source that is placed between the two focus lenses and directed to two opposing recording surfaces. a switching mirror that can rotate by 90 degrees, and one mirror that is placed at a position that allows the light beam from the light source to be moved in the radial direction of the disk via the switching mirror and focus lens. and a light receiving element that receives reflected light from the disk surface via the switching mirror and converts the optical signal into an electrical signal. .

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The first embodiment is shown together with an optical disk in the sectional view of FIG. To explain the figure, reference numerals 6 and 7 are focus lenses for focusing the light beam on the recording surface 8 or 9, respectively, voice coils 10 and 11, magnets 12 and 13, and yoke 1.
Focus adjustment is performed by a focus adjustment mechanism consisting of 4, 15 and support plate springs 16, 17. 18 is a 1/4 wavelength plate, and 19 is a switching mirror rotatable through 90 degrees, which rotates around an axis 20 within the range shown in the figure. Further, this mirror 19 is driven by a simple electromagnetic component such as a rotary solenoid.
A polarizing beam splitter 21 guides reflected light from the recording surface to a photodetector element 22 for focusing, tracking, and signal detection. Reference numeral 23 denotes an optical deflector for moving a light beam in the radial direction on the disk surface and performing track servo, which is a rotating mirror and is rotated about an axis 24. Further, 25 is a collimator lens system, and 26 is a laser diode.

The operation of this embodiment configured in this way will be described next. The light beam 27 emitted by the laser diode 26 passes through the collimator lens 25, the optical deflector 23, the beam splitter 21, and the quarter-wave plate 18, and reaches the switching mirror 19. In the state shown in the figure, the light beam is reflected toward the recording surface 8, further reflected from the recording surface 8, and reaches the polarizing beam splitter 21 along the same path. Since the plane of polarization of this reflected light has been rotated by 90 degrees by the quarter-wave plate 18, the light is guided to the detection element 22, where the optical signal is converted into an electrical signal. At the same time, the voice coil 10 is positioned in the gap between the magnet 12 and the yoke 14 to adjust the focus of the light beam.
The tracking servo of the light beam is performed by rotating the mirror of the optical deflector 23.

Further, in order to change the recording/reproduction from the recording surface 8 to the recording surface 9, it is sufficient to rotate the switching mirror 19 by 90 degrees, and the other operations are the same as those for the recording surface 8. Therefore, by switching the switching mirror 19, it is possible to alternately record and reproduce information on the two recording surfaces 8 and 9.

Note that this embodiment described above can be constructed by simply adding a focusing mechanism such as a focusing lens 7 and a switching mirror 19 for an optical head that can only be used for one recording surface, so it is not as functional as it should be. The size and weight can be reduced.

Further, the magnetic circuit of the focus adjustment mechanism can be combined into one as shown in FIG. To explain with the drawing, focusing lenses 30 and 31 supported by support leaf springs 28 and 29, respectively, are connected by a cylindrical member 32, and a magnet 33 is attached to the outside of the focusing lenses 30 and 31.
A yoke 34 is provided, and a voice coil 35 is connected to the cylindrical member 32 so as to cross the magnetic flux emitted from the yoke.
The focusing lenses 30 and 31 can be moved by controlling the current flowing through the voice coil 35. Note that 36 in the figure is a switching mirror, which is a cylindrical member 32.
It is inserted through a window 32a provided in the window 32a. In this way, the driving magnetic circuit of the focus adjustment mechanism can be integrated into one.

As explained above, the optical head of the present invention is capable of recording and reproducing data on two recording surfaces, and contributes to miniaturization of the optical disk device while increasing its storage capacity.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the principle of an optical disc device, Fig. 2 is a schematic explanatory diagram showing a cross section of an optical head for an optical disc device according to an embodiment of the present invention, and Fig. 3 is a perspective view of another embodiment. be. 6, 7, 30, 31... Focusing lens, 8, 9... Recording surface, 10, 11, 35... Voice coil, 12, 13, 33... Magnet, 14,
15, 34... Yoke, 16, 17, 28, 29...
...Support leaf spring, 18...1/4 wavelength plate, 19, 36
... Switching mirror, 21 ... Polarizing beam splitter, 22 ... Photo detection element, 23 ... Light deflector, 25 ... Collimator lens system, 26 ... Laser diode, 27 ... Light beam, 32 ... Cylindrical member.

Claims (1)

[Scope of utility model registration request] An optical head for an optical disk device using at least two or more disk surfaces as information recording surfaces, comprising two focus lenses facing each of the two opposing recording surfaces, and supporting the focus lenses; A 90° lens that is placed between one or two focus adjustment mechanisms that can adjust the focus and the two focus lenses, and that can switch the light beam from the light source to two opposing recording surfaces. a rotatable switching mirror; one optical deflector disposed at a position where the light beam from the light source can be moved in the disk radial direction via the switching mirror and the focus lens; 1. An optical head for an optical disk device, comprising a light receiving element that receives reflected light from the disk surface via the switching mirror and converts an optical signal into an electrical signal.