JPH08180442A - Optical pickup device - Google Patents

Abstract

PURPOSE: To obtain behavioral stability at the seek time of an objective lens in a simple constitution without using a photosensor. CONSTITUTION: Two wires 7a and 7b out of four wires are constituted of a piezoelectric ceramic element wire. At the tracking time, a switch 11 is turned on to the side of a tracking error signal T, and the tracking error signal T is amplified by an operational amplifier 12b, and then a tracking coil 6 is driven with a current by an operational amplifier 12c receiving the amplified tracking error signal T. At the seek time, the switch 11 is turned on to the side of an operational amplifier 12a, so that signals from the piezo-electric ceramic element wires are differentially amplified by the operational amplifier 12a, and is further amplified by the operational amplifier 12b, and then the tracking coil 6 is controlled to be driven with a current by the operational amplifier 12c with the amplified signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup device provided in an optical disc device or the like and used for reading an optical disc or the like.

[0002]

2. Description of the Related Art As a conventional method of stabilizing the behavior of an objective lens when seeking in an optical disk apparatus, a photonics sensor method is generally used. FIG. 3A is a side view of a main part of a conventional optical pickup device of an optical disk device, and FIG. 3B is a plan view of the same. In FIG. 3, reference numeral 1 is an objective lens, 2 is a lens holder for holding the objective lens 1, 3 is a yoke constituting a magnetic circuit, and a chassis base 8 of the optical pickup device.
Attached to. Reference numeral 4 is a permanent magnet, 5 is a focusing coil for driving the objective lens 1 with respect to the optical axis direction of the objective lens 1, 6 is a tracking coil for driving the objective lens 1 in a direction orthogonal to the optical axis direction, and 7 is a lens holder 2 Are four wires that support the optical axis of the objective lens 1 in the optical axis direction and the radial direction of the optical disk, and are attached to the chassis base 8. Reference numeral 9 is a reflector for reflecting the light from the photonics sensors 10a and 10b.

FIG. 4 is a drive circuit diagram of a conventional optical pickup device, and the operation will be described below with reference to the same figure. In the normal operation, first, the focus error signal F is amplified by the operational amplifier 12d, the focusing coil 5 is current-driven through the operational amplifier 12e, and feedback control is performed to perform the focusing operation. When the focusing operation is completed, the variable contact 11a of the switch 11 is turned on to the fixed contact 11b side. Switch 11 is fixed contact 11
When turned on to the b side, the tracking error signal T is amplified by the operational amplifier 12b, and the tracking coil 6 is current-driven through the operational amplifier 12c to perform feedback control to perform the tracking operation.

At the time of seek, the variable contact 11a of the switch 11 is turned on to the fixed contact 11c side. Switch 1
When 1 is turned on to the fixed contact 11c side, the tracking control signal shifts from the tracking error signal T to the output signals of the photonics sensors 10a and 10b. The output signals of the photonics sensors 10a and 10b are differentially amplified by the operational amplifier 12a, and the differentially amplified signals are further amplified by the operational amplifier 12b, and the tracking coil 6 is current-driven through the operational amplifier 12c to perform feedback control. By multiplying by, it is possible to stabilize the behavior of the objective lens at the time of seeking.

[0005]

However, in the above-mentioned conventional configuration, the reflector 9 and the photonics sensors 10a, 1 are provided.
0b is required, the structure of the optical pickup device is complicated, the weight of the optical pickup device itself is increased, and it is difficult to perform high-speed seek and miniaturize the optical pickup device.

Therefore, the present invention is to solve the above-mentioned conventional problems, and it is intended to stabilize the behavior of the objective lens at the time of seek without increasing the weight of the optical pickup device itself with a simple structure of the optical pickup device. It is an object of the present invention to provide an optical pickup device capable of

[0007]

In order to achieve the above object, the present invention provides an objective lens, a lens holder for holding the objective lens, and the lens holder in the optical axis direction of the objective lens by four wires. The four wires, which are finely supported in the radial direction of the optical disk, and at least one wire has a pressure sensor, and are fixed to the lens holder and driven in the optical axis direction of the objective lens. And a tracking coil that is driven in a direction orthogonal to the optical axis direction of the objective lens, a permanent magnet that forms a magnetic field that crosses the focusing coil and the tracking coil, and a yoke. , A driving circuit for generating a driving force for driving the focusing coil, and a driving force for driving the tracking coil. And a drive circuit for raw, during the seek are those having a mechanism for driving and controlling the tracking coil by a signal from the pressure sensor having the four wires.

[0008]

According to the above construction, since the state of the objective lens at the time of seek is detected by the pressure sensor of at least one of the four wires, the apparatus itself can be made compact and lightweight.

Further, with the above structure,
The output signal from the pressure sensor of the two wires is operated and amplified by the operational amplifier, and the tracking coil is current-driven through the operational amplifier to perform feedback control, making it easy to stabilize the behavior of the objective lens during seek. Can be planned.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a side view of a main part of an optical pickup device according to an embodiment of the present invention, FIG. 1B is the same plan view, FIG. 1C is the same sectional view, and FIG. 2 is the same optical pickup. It is a drive circuit diagram of an apparatus.

In FIG. 1, 1 is an objective lens, 2 is a lens holder for holding the objective lens 1, and 3 is a yoke constituting a magnetic circuit, which is attached to a chassis base 8 of the pickup device. 4 is a permanent magnet, 5 is a focusing coil for driving the objective lens 1 with respect to the optical axis direction, 6 is a tracking coil for driving the objective lens 1 in a direction orthogonal to the optical axis direction, and 7 is a lens holder 2. Are attached to the chassis base 8 and are composed of piezoelectric ceramic element wires 7a and 7b and metal wires 7c and 7d. The four wires finely support the objective lens 1 in the optical axis direction and the optical disc radial direction. Has been done.

Next, the operation will be described with reference to FIG.
In the normal operation, first, the focus error signal F is amplified by the operational amplifier 12d, the focusing coil 5 is current-driven through the operational amplifier 12e, and feedback control is performed to perform the focusing operation. When the focusing operation is completed, the variable contact 11a of the switch 11 is turned on to the fixed contact 11b side. When the switch 11 is turned on to the fixed contact 11b side, the tracking error signal T is amplified by the operational amplifier 12b, the tracking coil 6 is current-driven through the operational amplifier 12c, and feedback control is performed to perform the tracking operation. At the time of seeking, the variable contact 11a of the switch 11 is changed to the fixed contact 11
Turn on the c side. When the switch 11 is turned on to the fixed contact 11c side, the tracking control signal shifts from the tracking error signal T to the output signal from the piezoelectric ceramic element wires 7a and 7b. Piezoelectric ceramic element wire 7
The output signals of a and 7b are differentially amplified by the operational amplifier 12a, and the differentially amplified signal is further amplified by the operational amplifier 12b, and the tracking coil 6 is current-driven via the operational amplifier 12c to perform feedback control. Yes,
It is possible to stabilize the behavior of the objective lens 1 when seeking. Further, in the present embodiment, the piezoelectric ceramic elements 7a and 7b are used as pressure sensors provided on the four wires 7.
However, it is needless to say that the same effect can be obtained by using a metal strain gauge, a semiconductor strain gauge or the like (neither is shown).

According to this embodiment having the above-described structure, the behavior of the objective lens 1 can be stabilized during seek without using a photonics sensor as in the conventional case.

[0014]

As described above, according to the present invention, at least one of the four wires for supporting the lens holder in a finely movable manner has a pressure sensor so that the state of the objective lens at the time of seek can be determined. Since it can be detected, the device itself can be configured compactly.

Further, according to the present invention, at the time of seeking, the output signals from the pressure sensors of four wires are differentially amplified by the operational amplifier, and the tracking coil is current-driven and fed back through the operational amplifier. By applying the control, it is possible to easily stabilize the behavior of the objective lens at the time of seeking. Therefore, the device can be configured with a simple mechanism without using an optical sensor, and the device can be made lightweight, so that high-speed seek can be achieved.

[Brief description of drawings]

FIG. 1A is a side view of a main part of an optical pickup device according to an embodiment of the present invention. FIG. 1B is a plan view of a main part of an optical pickup device according to the embodiment of the present invention. Front sectional view of the main part of the optical pickup device in the example

FIG. 2 is a drive circuit diagram of an optical pickup device according to an embodiment of the present invention.

FIG. 3A is a side view of an essential part of an optical pickup device of a conventional optical disk device. FIG. 3B is a plan view of an essential part of an optical pickup device of a conventional optical disk device.

FIG. 4 is a drive circuit diagram of a conventional optical pickup device.

[Explanation of symbols]

 1 Objective Lens 2 Lens Holder 3 Yoke 4 Permanent Magnet 5 Focusing Coil 6 Tracking Coil 7 Four Wires 7a, 7b Piezoelectric Ceramic Element Wire 7c, 7d Metal Wire 11 Switch 12a, 12b, 12c, 12d, 12e Operational Amplifier

Claims (3)

[Claims] 1. An objective lens, a lens holder for holding the objective lens, and the lens holder supported by four wires so as to be finely movable in the optical axis direction of the objective lens and the radial direction of the optical disc, and at least 1. Wires having pressure sensors, a focusing coil fixed to the lens holder and driven in the optical axis direction of the objective lens, and an optical axis direction of the objective lens. An optical pickup device including a tracking coil that is driven in a direction orthogonal to the focusing coil, a permanent magnet that forms a magnetic field that crosses the focusing coil and the tracking coil, and a yoke, and that generates a driving force that drives the focusing coil. It has a drive circuit and a drive circuit that generates a drive force for driving the tracking coil, and is used when seeking. The optical pickup apparatus characterized by driving and controlling the tracking coil by a signal from the pressure sensor the four wires has the. 2. The optical pickup device according to claim 1, wherein the pressure sensor is composed of a piezoelectric ceramic element. 3. The pressure sensor comprises a metal strain gauge or a semiconductor strain gauge.
The optical pickup device described.