JP2003346363A - Optical head apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical head apparatus, which can drive a plurality of driving coils with a few feeding lines. <P>SOLUTION: In the optical head apparatus 1, three driving coils 10, 20 and 30 are electrically serially-connected, and four points, which include connection points between serially-connected driving coils, are electrically connected with wires 11A, 11B, 11C and 11D. In a drive circuit 50, signals (V11, V12, V13 and V14) are generated from original signals (+V1, +V2 and +V3) to independently drive each of the three driving coils 10, 20 and 30, and these signals are transmitted to both ends of driving coils 10, 20 and 30 through the wires 11A, 11B, 11C and 11D. Thereby, the subtraction voltage of the signal is applied to each of the driving coils 10, 20 and 30. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical head device used for recording and reproducing data on and from an optical recording medium. More specifically, the present invention relates to a driving technique for a magnetic drive circuit for driving an objective lens in the optical head device.

[0002]

2. Description of the Related Art In an optical head device for recording and reproducing data on and from an optical recording medium such as a CD, CD-R, or DVD, as shown in FIG. 2, a lens holder 13 for holding an objective lens 4 and a lens holder 13 are provided. To the four wires 11A, 11B,
A fixing member 12 supported via 11C and 11D, a focusing drive coil 10 and a tracking drive coil 20 fixed to a lens holder 13, and a drive for generating a magnetic flux linked to these drive coils 10 and 20 And a magnet 15. Here, a drive circuit (not shown) for the drive coils 10 and 20 includes a fixed member 1.
The power supply to the focusing drive coil 10 is performed using the wires 11A and 11B as power supply lines, and the power supply to the tracking drive coil 20 is performed using the wires 11C and 11D as power supply lines.

In the optical head device 1 configured as described above, when the focusing drive coil 10 and the tracking drive coil 20 are energized, the Lorentz force generated thereby causes the lens holder 13 holding the objective lens 4 to move in the focusing direction (X). Direction) and the tracking direction (Y direction).

Further, in the optical head device 1, if the optical axis 9 of the objective lens 4 is inclined with respect to the optical recording medium, there is a problem in recording and reproduction on the optical recording medium. So, for example,
A drive coil 30 for tilt control is provided at the bottom of the lens holder 13.
And permanent magnets 14A and 14B for generating magnetic flux interlinking with the drive coil 30 are arranged on both sides of the lens holder 13, and when the coil 30 is energized, the lens holder 13 is moved in the Z direction. Generates a couple around the axis extending to. Therefore, the inclination of the lens holder 13 can be adjusted by this couple, so that the inclination of the objective lens 4 can be adjusted.

[0005]

However, in the optical head device 1, as shown in FIG. 4, power is supplied to the focusing drive coil 10 via wires 11A and 11B, and power is supplied to the tracking drive coil 20 by wires. 11C and 11D, the addition of the tilt control drive coil 30 to the lens holder 13 requires additional wires 11E and 11F to supply power to the drive coil 30. The addition of such a wire leads to an increase in cost, the resonance mode becomes complicated, and the open-loop characteristics and the like may be deteriorated.

[0006] In view of the above problems, an object of the present invention is to provide:
An object of the present invention is to provide an optical head device capable of driving a plurality of drive coils with a small number of power supply lines.

[0007]

According to the present invention, there is provided a lens holder for holding an objective lens, a plurality of drive coils fixed to the lens holder, and a plurality of drive coils. An optical head device comprising: a drive magnet for generating magnetic flux interlinking with each other; and a drive circuit for feeding the drive coil from a fixed member side through a plurality of feed lines to drive the lens holder in a predetermined direction. Wherein, when n is an integer of 2 or more, the drive circuit includes n drive coils as the plurality of drive coils, and (n + 1) feed lines as the plurality of feed lines. Independently driving each of the n drive coils by a differential voltage of a drive signal supplied from the drive circuit via each of the (n + 1) power supply lines And it features.

In the present invention, since the drive coils are driven by the difference voltage of the signal generated from the original signal, (n + 1) power supply lines are required to drive the n drive coils independently. Therefore, in the optical head device, when performing tilt control in addition to focusing control and tracking control, it is not necessary to add a power supply line for supplying power to the tilt control drive coil. Therefore, in the optical head device of the wire suspension system, it is possible to avoid an adverse effect caused by adding a wire as a power supply line, that is, an increase in cost and a deterioration in open loop characteristics.

In the present invention, the n drive coils are, for example, electrically connected in series, and each of the (n + 1) power supply lines includes a connection point between the drive coils connected in series (n + 1). ) Electrical connection to the location.

In the present invention, for example, n is an integer of 3 or more, and the n drive coils include at least a focusing drive coil for driving the objective lens in a focusing direction, and a focusing drive coil for driving the objective lens in a tracking direction. It includes a tracking drive coil for driving. Furthermore, the n drive coils may include a tilt control drive coil that controls the tilt of the objective lens by generating a couple in the objective lens or the lens holder.

In the present invention, the power supply line is, for example, a wire that connects the fixed member side and the lens holder side and elastically supports the lens holder.

[0012]

Embodiments of the present invention will be described with reference to the drawings. Note that the embodiments described below are
Since the basic configuration is common to the conventional one, the common parts will be described with the same reference numerals.

[Overall Configuration] FIGS. 1 and 2 are a schematic configuration diagram of an optical head device to which the present invention is applied and an explanatory diagram showing a configuration around a lens holder used in the optical head device. In FIG. 2, a part of the drive magnet 15 is cut away.

In FIG. 1, in an optical head device 1 for recording and reproducing data on and from an optical recording medium such as a CD, CD-R, or DVD, a laser beam emitted from a laser light source 2 is reflected by a half mirror 3 and an objective lens. The light is condensed at 4 and focuses on the information recording surface of the optical recording disk 5. Here, the objective lens 4
Is held by a lens holder described later. The return light reflected by the optical recording disk 5 passes through the objective lens 4 and the half mirror 3 and enters the light detector 6. The light incident on the photodetector 6 is converted into an electric signal in the photodetector 6, and is converted into audio information or image information.

In order to correctly reproduce information in this type of apparatus, the objective lens 4 is moved while the optical axis of the objective lens 4 is perpendicular to the recording surface of the optical recording disk 5, and the deflection of the optical recording disk 5 is controlled. You have to follow the eccentricity. That is, for a focusing error, the objective lens 4 is driven in the vertical direction (focusing direction) to correct this, while for a tracking error, the objective lens 4 is driven in the horizontal direction (tracking direction). Needs to be corrected.

Therefore, as described with reference to FIG. 2, the optical head device 1 includes a lens holder 13 for holding the objective lens 4 and the lens holder 13 connected to the four wires 1.
A fixing member 12 supported via 1A, 11B, 11C, and 11D, a focusing driving coil 10 and a tracking driving coil 20 fixed to the lens holder 13, and are linked to the driving coils 10, 20. And a drive magnet 15 for generating a magnetic flux.
Accordingly, when the focusing drive coil 10 and the tracking drive coil 20 are energized, the lens holder 13 holding the objective lens 4 is driven in the focusing direction (X direction) and the tracking direction (Y direction) by the generated Lorentz force. be able to.

Also, in the optical head device 1, if the optical axis 9 of the objective lens 4 is inclined with respect to the optical recording medium, recording and reproduction on the optical recording disk 5 are hindered. In the optical head device 1, the lens holder 13
The tilt control drive coil 30 is mounted on the bottom of the lens holder 13, and permanent magnets 14A and 14B for generating magnetic flux interlinking with the drive coil 30 are disposed on both sides of the lens holder 13. Therefore, when the drive coil 30 for tilt control is energized, a couple around the axis extending in the Z direction can be generated with respect to the lens holder 13, so that the inclination of the lens holder 13, that is, the inclination of the objective lens 4 can be reduced. Can be adjusted.

[Description of Driving Method of Driving Coil] FIG.
FIG. 3 is an equivalent circuit diagram illustrating a circuit configuration on a lens holder side and a drive circuit side of the optical head device to which the present invention is applied.

In the optical head device 1, in the present embodiment, the three drive coils 10, 20, and 30 can be driven independently with the number of wires used as the power supply line being four. Is adopted.

First, as shown in FIG.
3, the three drive coils 10, 20, 30 are electrically connected in series, and a plurality of drive coils 10, 20, 30 are connected at four points including connection points 45, 46 between the drive coils connected in series. Four terminals 41, 4 are connected via resistance components 21, 22, 23, 24 of a shared line connecting the terminals 20, 30
2, 43 and 44 are electrically connected. Wires 11A, 11B, 11C, and 11D are electrically connected to the terminals 41, 42, 43, and 44, respectively.

On the other hand, in the drive circuit 50, three terminals 51 to which original signals (+ V1, + V2, + V3) for independently driving the three drive coils 10, 20, 30 are inputted. , 52, 53 and their original signals (+ V
1, + V2, + V3) (−V
1, -V2, -V3) and polarity inversion circuits 61, 62, 63 provided with inversion amplifiers for generating three original signals (+ V
1, + V2, + V3) and their inverted signals (−V
1, -V2, -V3) to add predetermined signals to generate output signals (V11, V12, V13, V14), and adders 71, 7, 74.
2, 73, 74 (V11, V12, V1
3, V14) respectively with wires 11A, 11B, 11
Output terminals 81, 82, 8 for outputting to C and 11D
3 and 84 are constituted. Output terminals 81 and 8
2, 83 and 84 are respectively electrically connected to the terminals 41, 42, 43 and 44 of the lens holder 13 via wires 11A, 11B, 11C and 11D, respectively. . The polarity inversion circuits 61 and 6
2, 63 and the addition circuits 71, 72, 73, 74 use electric elements such as input resistors.

In the driving circuit 50 configured as described above, the adder circuits 71, 72, 73, and 74 output four output signals (V11, V12, V13, and V13) represented by the following equation (1).
14) and the lens holder 13 outputs the output signals (V11, V12, V13,
V14), the difference voltages ΔV10, ΔV20, ΔV30 are applied to the respective drive coils 10, 20, 30.
0, 20, and 30 are driven.

[0023]

(Equation 1) V11 = (+ V1) + (+ V2) + (+ V3) V12 = (− V1) + (+ V2) + (+ V3) V13 = (− V1) + (− V2) + (+ V3) V14 = (− V1) + (− V2) + (− V3)

[0024]

ΔV10 = V11−V12 = 2 × (+ V1) ΔV20 = V12−V13 = 2 × (+ V2) ΔV30 = V13−V14 = 2 × (+ V3) That is, each of the drive coils 10, 20, 30 Differential voltages (ΔV10, ΔV20, ΔV30) corresponding to twice the original signals (+ V1, + V2, + V3) are applied independently of the signals supplied to the other drive coils. Accordingly, only by generating the original signals (+ V1, + V2, + V3) having a voltage corresponding to 1/2 of the original signals (+ V1, + V2, + V3) to be applied to the drive coils 10, 20, and 30, the drive coil 10 , 20, 30 with four wires 11
A, 11B, 11C, and 11D can be independently driven. Therefore, in the optical head device 1 of the present embodiment, even when the tilt control is applied in addition to the focusing control and the tracking control, the wires 11A, 11B, 1
Since it is not necessary to increase the number of 1C and 11D, it is possible to avoid the adverse effects caused by adding wires, that is, increase in cost and deterioration of open loop characteristics.

[Other Embodiments] In the embodiment shown in FIG. 3, four terminals 41, 4 are provided at four locations including connection points 45, 46 between drive coils 10, 20, 30 connected in series.
2, 43, 44 and wires 11A, 11B, 11
Although C and 11D were electrically connected, FIG.
The present invention may be applied to an optical head device having a configuration in which three drive coils 10, 20, and 30 are electrically connected to a common line 16 as shown in FIG.

In the above embodiment, the case where tilt control is performed in addition to focusing control and tracking control has been described as an example. However, the present invention is not limited to this, and the present invention is applied to an optical head device having n drive coils. If applied, (n
+1) It is possible to drive each drive coil independently of the power supply lines.

The drive circuit has resistance components 21, 22, 23, 2 which are included in a shared line connecting a plurality of drive coils.
A function of correcting a crosstalk component caused by the fourth method may be added.

[0028]

As described above, according to the present invention, since the drive coils are driven by the difference voltage of the signal generated from the original signal, when driving the n drive coils independently,
Only (n + 1) power supply lines are required. Therefore, in the optical head device, even when performing tilt control in addition to focusing control and tracking control, it is not necessary to add a wire. Can be avoided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an optical head device to which the present invention is applied.

FIG. 2 is an explanatory diagram showing a configuration around a lens holder used in an optical head device to which the present invention is applied, with a part of a driving magnet being cut away.

FIG. 3 is an equivalent circuit diagram showing a circuit configuration on a lens holder side and a drive circuit side of the optical head device to which the present invention is applied.

FIG. 4 is an equivalent circuit diagram showing a circuit configuration on a lens holder side of another optical head device to which the present invention is applied.

FIG. 5 is an equivalent circuit diagram showing a circuit configuration on a lens holder side of a conventional optical head device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Optical head device 2 Laser light source 3 Half mirror 4 Objective lens 5 Optical recording disk 6 Photodetector 10 Focusing drive coils 11A, 11B, 11C, 11D Wire (feeding line) 12 Fixing member 13 Lens holder 14A, 14B For tilt control Permanent magnet 15 Drive magnet 16 Common line 20 Tracking drive coil 30 Tilt control coils 41, 42, 43, 44 Terminals 61, 62, 63 on lens holder side Polarity inversion circuits 71, 72, 73, 74 Addition circuits 81, 82 , 83, 84 Fixed member side + V1, + V2, + V3 Original signal ΔV10, ΔV20, ΔV30 Difference voltage

Claims (5)

[Claims] A lens holder for holding an objective lens;
A plurality of drive coils fixed to the lens holder, a drive magnet that generates a magnetic flux linked to each of the plurality of drive coils, and power is supplied from the fixed member side to the drive coil through a plurality of power supply lines. A driving circuit for driving the lens holder in a predetermined direction, wherein when n is an integer of 2 or more, the optical head device has n driving coils as the plurality of driving coils and the plurality of driving coils. Have (n + 1) power supply lines as
The drive circuit independently drives each of the n drive coils by a difference voltage of a drive signal supplied from the drive circuit via each of the (n + 1) power supply lines. Head device. 2. The drive coil according to claim 1, wherein the drive coils are electrically connected in series to the n drive coils, and the (n + 1) power supply lines are respectively connected to connection points between the drive coils connected in series. An optical head device electrically connected to (n + 1) locations including: 3. The method according to claim 1, wherein n is an integer of 3 or more, and the n drive coils are at least:
An optical head device comprising: a focusing drive coil that drives the objective lens in a focusing direction; and a tracking drive coil that drives the objective lens in a tracking direction. 4. The drive coil according to claim 3, wherein the n drive coils further include a tilt control drive coil for controlling a tilt of the objective lens by generating a couple in the objective lens or the lens holder. An optical head device. 5. The method according to claim 1, wherein
The optical head device, wherein the power supply line is a wire that connects the fixed member side and the lens holder side and elastically supports the lens holder.