JPH052765A - Actuator for optical pickup - Google Patents

Abstract

PURPOSE:To obtain an optical pickup device with a high performance by preventing dust from intruding from an opening 10 into an actuator 8 and removing an optical adverse influence due to the intrusion of the dust or the like, at the time of a non-operation. CONSTITUTION:An optical recording medium 1 is irradiated with a beam light outgoing from a light source in order to operate the recording and reproduction of information. At the time of the non-operation, an actuator 8 is set to be in touch with an actuator cover 9. At the time of an operation, the offset currents of an offset generating circuit are superimposed on a focus error signal and supplied to a focus coil, so that the actuator 8 can be detached from the actuator cover 9 and not in touch with it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical pickup actuator in an optical information recording / reproducing apparatus such as an optical disc player.

[0002]

2. Description of the Related Art Conventionally, in an optical pickup device used in an optical recording / reproducing device such as an optical disk player, laser light emitted from a semiconductor laser passes through a half mirror and a collimator lens and is focused by an objective lens. A read operation or a write operation of information on the disk is performed.

Further, the focus of the laser beam focused by the objective lens must always be aligned with the signal surface of the disc, so that the distance between the objective lens and the disc signal surface must be constant. Therefore, in order to make the laser beam follow the displacement of the signal surface track due to the vertical swing of the disk when the disk of the recording medium is driven, an actuator that drives the objective lens up and down is used.

As shown in FIG. 8, the above-mentioned actuator uses the focus error signal S to determine the position of the track of the disk 1 and the amount of focus deviation of the laser light 4 emitted from the semiconductor laser in the pickup device 2 and focused by the objective lens 3. _The signal S _F is detected as _F , amplified by the amplifier circuit 5, passed through the actuator drive circuit 6, and then input to the focus coil 7 to drive and control the objective lens 3.

Further, as shown in FIG. 7, the actuator 8 is covered with an actuator cover 9, and the actuator cover 9 has an optical path of the laser beam 4 between the objective lens 3 and the signal surface of the disk 1. The opening 10 is formed in order to secure the above. The actuator 8 for driving the objective lens 3 in the vertical direction is
It is supported by the intermediate support 12 via the upper and lower leaf springs 11 and is in non-contact with the actuator cover 9.

[0006]

However, in the structure of the conventional actuator for an optical pickup described above, since the actuator cover 9 is provided with the opening 10, it is easy for dust to enter from the outside, and the actuator cover is not provided. A situation occurs such that dust or the like adheres to the optical components and the like inside 9. If dust adheres to the optical system path of the objective lens 3 etc., it causes a decrease in transmittance and reflectance, and the amount of light incident on the light receiving element decreases, which in turn enables normal reading and writing of information on the disc. It has the problem of disappearing.

[0007]

SUMMARY OF THE INVENTION The present invention relates to an optical pickup actuator for recording / reproducing information by irradiating an optical recording medium with a light beam emitted from a light source. When the actuator is not in operation, the actuator contacts the actuator cover. The actuator is disengaged from the actuator cover by the offset means so that the actuator is not in contact with the actuator cover during operation.

Further, the actuator is positioned above the optical recording medium, and the actuator is set so as to contact the actuator cover by its own weight when the actuator is not operating. It is designed to be

Further, as the offset means, when the track position of the optical recording medium and the shift amount of the focus of the light beam are detected as a focus error signal, amplified, and input to the focus coil after passing through the actuator drive circuit, on the way. The offset current of the offset generating circuit provided in the above is superposed on the focus error signal so that the actuator comes out of the actuator cover and is not in contact with it.

[0010]

In the optical pickup actuator according to the present invention, the actuator and the actuator cover are in contact with each other when not in operation because of the above-described structure.
Dust or the like from the outside does not enter the inside of the actuator cover, and since the actuator and the actuator cover are in a non-contact state during operation, the driving of the objective lens is not hindered.

When the actuator is positioned above the optical recording medium, it is possible to reduce the intrusion of dust and the like into the actuator not only when it is not operating but also when it is operating.

Further, by inserting the offset generating circuit in the middle of the objective lens drive control circuit in the focus direction, the actuator and the actuator cover can be kept in non-contact with each other during operation.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical pickup actuator of the present invention is provided with a semiconductor laser, a half mirror as an optical system member, a collimator lens, an objective lens, an actuator, a light receiving element, etc., as in the conventional case.

Laser light is emitted from the semiconductor laser, reflected by a half mirror, collimated by a collimator lens, and incident on an objective lens.

Further, as shown in FIG. 6, the actuator 8 has a focus coil 14, a focus servo magnet 15 and two upper and lower surfaces in order to drive the objective lens 3 supported by the support portion 13 in the vertical direction. Leaf spring 1
And a radial coil 16 and two left and right leaf springs 17 for driving the objective lens 3 in the left-right direction.
It consists of and. In addition, the above four leaf springs 11 and 17
Are supported by the intermediate support 12.

When the actuator 8 receives a focus servo signal from a light receiving element (not shown), a current corresponding to the focus servo signal is applied to the focus coil 14.
Is applied to the focus coil 14 and the focus servo magnet 15, an electromagnetic induction action is generated, and the objective lens 3 is driven in the vertical direction. Also, when receiving the radial servo signal, the objective lens 3 is driven in the left-right direction similarly to the focus servo signal.

A laser beam reflected by a disk as a recording medium passes through the objective lens 3, a collimator lens (not shown) and a half mirror and is incident on a light receiving element. A servo that adjusts the focus position of the laser light to the track position of the disk by detecting the shift in the focus direction between the track position of the disk from the laser light incident on the light receiving element and the focus position of the laser light emitted from the objective lens. The signal is input to the actuator.

The dustproof mechanism of the optical pickup actuator in the optical information recording / reproducing apparatus having the above construction will be described below.

As shown in FIG. 1, when the optical pickup device is not in operation, the objective lens 3, the focus coil 14, the focus servo magnet 15, and the plate, which are also supported by the supporting portion 13, are also shown in FIG. The actuator 8 including the spring 11 and the intermediate support 12 and the actuator cover 9 that covers the actuator 8 are in contact with each other, and have a structure for preventing dust from entering.

Next, as shown in FIG. 2, when the optical pickup device is in operation, the objective lens 3 is lowered by the offset means through the leaf spring 11 in the direction away from the disc 1, and the actuator 8 and the actuator cover 9 are provided. Are in a non-contact state, and the structure is such that movement of the actuator 8 in the vertical direction due to the servo signal is not hindered.

Another embodiment of the dustproof mechanism of the optical pickup actuator will be described below.

As shown in FIG. 3, when the actuator 8 of the optical pickup device is positioned above the disk 1 and is not in operation, the objective lens 3 supported by the supporting portion 13 is also shown in FIG. The actuator 8 composed of the focus coil 14, the focus servo magnet 15, the leaf spring 11 and the intermediate support 12 and the actuator cover 9 covering the actuator 8 are in contact with each other due to the weight of the actuator, so that dust may not enter. It has a structure to prevent it.

Next, as shown in FIG. 4, when the optical pickup device is in operation, the objective lens 3 is raised by the offset means via the leaf spring 11 in the direction away from the disc 1, and the actuator 8 and the actuator cover 9 are provided. Are in a non-contact state, and similarly to the above, the structure is such that there is no hindrance to the vertical movement of the actuator 8 associated with the servo signal.

Further, the offset means for bringing the actuator 8 and the actuator cover 9 into a non-contact state detects the deviation amount between the track position of the disk 1 and the focus of the laser light as a focus error signal S _F , and the amplifier circuit 5
Is amplified and supplied to the actuator drive circuit 6.
On the other hand, the offset current S of the offset generation circuit 18
_O is supplied to the actuator drive circuit 6,
It is superimposed on the amplified focus error signal S _F and input to the focus coil 7 to drive and control the objective lens 3.
The offset current S _O of the offset generation circuit 18 is
Is supplied to a portion other than the above circuit and the focus error signal S
_May be superimposed on _F.

[0025]

Since the optical pickup actuator according to the present invention is constructed as described above, when the actuator and the actuator cover are not in operation, the actuator is in a neutral state or is in contact with itself due to its own weight. During operation, it is possible to maintain a non-contact state by superimposing an offset current on the focus coil.

Further, this prevents dust from entering the actuator through the opening when it is not operating, and removes optical adverse effects due to the entry of dust or the like, thereby enabling a high-performance optical pickup device. .

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an optical pickup actuator of the present invention when not in operation.

FIG. 2 is a schematic cross-sectional view of the optical pickup actuator of FIG. 1 during operation.

FIG. 3 is a schematic cross-sectional view of an optical pickup actuator according to another embodiment of the present invention when not in operation.

4 is a schematic cross-sectional view of the optical pickup actuator of FIG. 3 during operation.

FIG. 5 is a block circuit diagram showing control of the actuator during operation in the optical pickup actuator according to the present invention.

FIG. 6 is a perspective view of a general optical pickup actuator.

FIG. 7 is a schematic cross-sectional view of a conventional optical pickup actuator.

FIG. 8 is a block circuit diagram showing control of a conventional optical pickup actuator.

Claims (3)

[Claims] 1. An optical pickup actuator for recording / reproducing information by irradiating an optical recording medium with a light beam emitted from a light source, wherein the actuator is set so as to come into contact with an actuator cover when not in operation, and is in operation. An actuator for an optical pickup, wherein the actuator is detached from the actuator cover by an offset means so as not to come into contact with the actuator cover. 2. The actuator according to claim 1, wherein the actuator is positioned above the optical recording medium, and the actuator is set so as to contact the actuator cover by its own weight when not operating. Actuator for optical pickup. 3. The offset generating circuit, as the offset means, detects a deviation amount between the track position of the optical recording medium and the focus of the light beam as a focus error signal, amplifies it, and inputs it to a focus coil via an actuator drive circuit. 2. The actuator for optical pickup according to claim 1, wherein the actuator is detached from the actuator cover and is not in contact with the focus error signal by superimposing the offset current on the focus error signal.