JP2008226305A - Optical pickup and driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical pickup capable of being easily subjected to tilting (inclination correcting operation) with high accuracy in a simple configuration without causing complicatedness and high cost of a device, and a driving device. <P>SOLUTION: The optical pickup for reading/writing information from/to an optical disk and performing a focus operation and a tracking operation comprises: an objective lens for converging light on the optical disk; an objective lens holder for holding the objective lens; a plurality of wires, one end of which is connected to the objective lens holder; a support member for supporting the lens holder freely rotatably through the plurality of wires in which the other end of the plurality of wires is connected; and a wire displacing means for making the objective lens holder perform tilting by slightly displacing a part adjacent to the support member of the wires. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical pickup and a driving device, and more particularly to an optical pickup that corrects an inclination between an optical axis of a light beam and an optical disk surface.

  Conventionally, CDs and DVDs are known as information recording media using optical disks. In recent years, blue laser systems (BD, HDDVD) have been studied, and the recording density of optical discs has been increasing. Along with this, an optical pickup that reads and writes information from and on an optical disc is required to have high performance.

  For example, the optical axis of the optical pickup and the disk surface are ideally vertical, but in reality, they are not always vertical due to various factors such as errors in the optical disk and optical disk apparatus.

  In the optical disk reproducing apparatus, when the optical axis of the signal reproducing beam is inclined with respect to the optical disk reproducing surface, optical aberration occurs, crosstalk increases, and the reproduced signal deteriorates. Further, in the optical disk recording / reproducing apparatus, if the optical axis of the signal recording beam is inclined with respect to the optical disk recording surface, the recording signal may be deteriorated and a pit formation may be missed.

Therefore, various methods for correcting the inclination between the optical axis of the optical pickup and the disk surface have been studied. For example, as in the focus and tracking operation mechanism, there is known a method of correcting by tilting an objective lens holder for holding an objective lens by providing a coil and a magnet (see Patent Document 1). In addition, a method of correcting by deforming a wire holding the objective lens holder is known (see Patent Document 2).
JP-A-7-65397 JP 2002-92915 A

  However, with the method disclosed in Patent Document 1, there are two electromagnetic driving portions, or the thickness direction becomes thick because four tilt coils are arranged on one side, so that the actuator itself becomes large and heavy, There is a problem that miniaturization of the optical disk device is hindered. In addition, the method disclosed in Patent Document 2 is a configuration that is not easy to realize, such as connecting a conductive element to a conductive wire while insulating the piezoelectric element. Furthermore, in order to perform rotation (radial tilt) about the wire as an axis, eight piezoelectric elements are required, resulting in an increase in the cost and complexity of the device.

  The present invention has been made in view of the above problems, and an optical pickup capable of easily performing a highly accurate tilt operation (tilt correction operation) with a simple configuration without incurring complexity and cost of the apparatus, and driving An object is to provide an apparatus.

  The above object is achieved by the invention described in any one of 1 to 8 below.

1. In an optical pickup that reads / writes information from / to an optical disc and performs focusing and tracking operations.
An objective lens for condensing light on the optical disc;
An objective lens holder for holding the objective lens;
A plurality of wires having one end coupled to the objective lens holder;
A support member that is coupled to the other ends of the plurality of wires and rotatably supports the lens holder via the plurality of wires;
An optical pickup comprising: a wire displacing means for tilting the objective lens holder by minutely displacing a portion of the wire adjacent to the support member.

  2. The wire displacing means causes the objective lens holder to move in a direction perpendicular to both the focus direction and the tracking direction by minutely displacing at least two portions of the wire adjacent to the support member in different directions. The optical pickup according to 1 above, wherein the optical pickup is rotated as follows.

3. The wire displacement means is
A lever member on which at least two wires are hooked and rotatably supported;
3. The optical pickup according to 2 above, further comprising: 1 drive source for finely rotating the lever member.

  4). The wire displacing means rotates the objective lens holder about the tracking direction by minutely displacing at least two portions of the wire adjacent to the support member in the same direction. The optical pickup described in 1.

5. The support member includes a first support member to which at least two wires are coupled, and a second support member to which the other wires are coupled,
The wire displacement means is
A hinge portion for rotatably supporting the first support member;
5. The optical pickup according to 4, further comprising: a drive source that rotates the first support member slightly.

  6). The wire displacing means selectively displaces the portion of the at least two wires adjacent to the support member by minute displacement, thereby moving the objective lens holder in a direction perpendicular to both the focus direction and the tracking direction and the tracking direction. 2. The optical pickup according to 1 above, wherein the optical pickup is rotated around an axis in one of the directions.

  7. The optical pickup according to any one of 1 to 6, wherein the wire displacing means includes a shape memory alloy.

8). A driven part which is a driven object;
A wire having one end coupled to the driven portion;
A support member to which the other end of the wire is coupled and movably supports the driven part via the wire;
A drive unit comprising: drive means for driving the driven part by minutely displacing a portion of the wire adjacent to the support member.

  According to the present invention, the wire displacing means causes the objective lens holder to be tilted by minutely displacing the portion of the wire coupled to the objective lens holder that is close to the support member. Since the portion of the wire adjacent to the support member is displaced, the objective lens holder can be tilted with a large amplitude with a slight displacement. In addition, it is possible to suppress the influence of the tilt operation on the focus and tracking operations. Thereby, a highly accurate tilt operation (tilt correction operation) can be easily performed with a simple configuration.

  Embodiments of an optical pickup according to the present invention will be described below with reference to the drawings. In addition, although this invention is demonstrated based on embodiment of illustration, this invention is not limited to this embodiment.

Embodiment 1
FIG. 1 shows a configuration of an optical pickup according to the first embodiment. FIG. 1 is a diagram illustrating a schematic configuration of an optical pickup 1 according to the first embodiment. As shown in FIG. 1, the optical pickup 1 includes an objective lens 101, an objective lens holder 102, a wire fixing portion 103, a wire 105, a shape memory alloy 107, and the like.

  The objective lens holder 102 that holds the objective lens 101 and corresponds to the driven portion in the present invention is connected to the wire fixing portion 103 that corresponds to the support member in the present invention via the four wires 105a to 105d that perform elastic deformation. It is supported so as to be movable, and can be translated in the focus direction (Y direction) and the tracking direction (X direction) by conventional electromagnetic means (not shown). Here, the rotation indicated by the arrow R with the axis perpendicular to the focus direction (Y direction) and the tracking direction (X direction), that is, the Z direction as the axis, and the tracking direction (X direction) as the axis. The rotation indicated by the arrow T is referred to as a tangential tilt operation.

  The optical pickup 1 according to Embodiment 1 causes the objective lens holder 102 to perform a radial tilt operation. In the vicinity of the wire fixing portion 103 of the wire 105d, a linear shape memory alloy (hereinafter referred to as SMA) 107 is installed in a V shape. Both ends of the SMA 107 are connected to terminals 108 provided on a base (not shown). The SMA 107 expands and contracts to a predetermined length by a current supplied from the drive / control circuit via the terminal 108 and causes the objective lens holder 102 to perform a radial tilt operation.

  FIG. 2 shows a state of the radial tilt operation. 2A and 2B are schematic views showing a radial tilt operation when viewed from the direction of arrow A1 in FIG.

  When the SMA 107 is not energized, as shown in FIG. 2A, the objective lens holder 102 maintains a horizontal posture. When the SMA 107 is energized, the SMA 107 contracts to a predetermined length according to the amount of current, and as shown in FIG. 2B, the wire 105d on which the SMA 107 is hooked is slightly displaced in the direction of the arrow Y1. As a result, the objective lens holder 102 rotates clockwise in FIG. When energization to the SMA 107 is stopped, the SMA 107 is extended, and the objective lens holder 102 is rotated counterclockwise by the elasticity of the wire 105d, and returns to the original horizontal state. Thus, the SMA 107 functions as a wire displacing unit and a driving unit in the present invention.

  In such a configuration, for example, since the displacement of the portion of the wire 105d where the SMA 107 is hooked is about 0.1 mm and the objective lens holder can be set to rotate about 1 degree, the configuration is very simple. With this, radial tilt operation becomes possible.

[Embodiment 2]
FIG. 3 shows the configuration of the optical pickup according to the second embodiment. FIG. 3 is a diagram showing a radial tilt mechanism of the optical pickup 1 according to the second embodiment viewed from the direction corresponding to the arrow A2 in FIG. The optical pickup 1 according to the second embodiment is a modification of the first embodiment, and causes the objective lens holder 102 to perform a radial tilt operation.

  In the case of the first embodiment, as described above, the objective lens holder 102 is rotated only in the lower region with reference to the horizontal position. In the case of the second embodiment, the bias spring 109 is used. Thus, the objective lens holder 102 is rotated in the upper and lower regions with respect to the horizontal position.

  When the force generated by the current supplied to the SMA 107 is smaller than the force of the bias spring 109, the objective lens holder 102 rotates clockwise in FIG. On the other hand, when the force generated by the current supplied to the SMA 107 is larger than the force amount of the bias spring 109, the objective lens holder 102 rotates counterclockwise. Thus, the SMA 107 and the bias spring 109 function as wire displacement means in the present invention.

[Embodiment 3]
FIG. 4 shows the configuration of the optical pickup according to the third embodiment. FIG. 4 is a diagram showing a radial tilt mechanism of the optical pickup 1 according to the third embodiment viewed from the direction corresponding to the arrow A2 in FIG. The optical pickup 1 according to the third embodiment is a modification of the first embodiment, and causes the objective lens holder 102 to perform a radial tilt operation.

  In the case of the third embodiment, the lever 110 is used to slightly displace the two wires 105c and 105d.

  The drive source for minutely displacing the wires 105c and 105d is only one of the SMA 107, and the lever 110 that is rotatably supported by the rotating shaft 111 is rotated by the balance of the forces of the SMA 107 and the bias spring 109, The two wires 105c and 105d hooked on the lever 110 are slightly displaced in different directions. Thus, the SMA 107, the bias spring 109, and the lever 110 function as wire displacement means in the present invention.

  If the two wires 105c and 105d are slightly displaced in different directions, the influence of the focusing operation can be suppressed. In the case of the first and second embodiments, if the focus operation is performed while performing the radial tilt operation, the tilt of the objective lens holder 102 is changed by the wire elastically deformed by the focus operation. Since the movement of the wire due to the focusing operation is canceled by the rotation, the inclination of the objective lens holder 102 does not change.

[Embodiment 4]
FIG. 5 shows the configuration of the optical pickup according to the fourth embodiment. FIG. 5 is a diagram showing a radial tilt mechanism of the optical pickup 1 according to the fourth embodiment as viewed from the direction corresponding to the arrow A2 in FIG. An optical pickup 1 according to the fourth embodiment is a modification of the third embodiment, and causes the objective lens holder 102 to perform a radial tilt operation.

  In the case of the fourth embodiment, the lever 110 is used to slightly displace the four wires 105a to 105d.

  The drive source for minutely displacing the wires 105a to 105d is only one of the SMAs 107 as in the case of the third embodiment, and is rotatably supported by the rotating shaft 111 by the balance of the forces of the SMA 107 and the bias spring 109. The lever 110 is rotated to slightly displace the four wires 105a to 105d hooked on the lever 110 in different directions.

  In this way, by finely displacing the four wires 105a to 105d in different directions, the center of the objective lens 101 can coincide with the rotational center of the radial tilt operation. As a result, in the case of the first to third embodiments, the focus and tracking position change with the radial tilt tilt operation. Therefore, it has been necessary to correct these by the focus and tracking driving means. This is not necessary, and only the radial tilt tilt operation can be performed independently.

[Embodiment 5]
FIG. 6 shows the configuration of the optical pickup according to the fifth embodiment. FIG. 6 is a diagram showing a tangential tilt mechanism of the optical pickup 1 according to the fifth embodiment viewed from the direction corresponding to the arrow A2 in FIG. The optical pickup 1 according to Embodiment 5 causes the objective lens holder 102 to perform a tangential tilt operation.

  A hinge 104 that elastically deforms is provided in the substantially central portion of the wire fixing portion 103, and the wire fixing portion 103a that fixes the two wires 105a and 105b is supported by the wire fixing portion 103b through the hinge 104 so as to be able to rotate slightly. Has been. Only one SMA 107 is the driving source for minutely displacing the wires 105a and 105b. The wire fixing portion 103a and the wire fixing portion 103b correspond to the first support member and the second support member in the present invention, respectively. The SMA 107 installed on the wire fixing portion 103a expands and contracts to a predetermined length by a current supplied from a drive / control circuit (not shown) via a terminal 108, and performs a tangential tilt operation on the objective lens holder 102. It is what you do.

  FIG. 7 shows the state of the tangential tilt operation. FIGS. 7A and 7B are schematic views showing a tangential tilt operation when viewed from the direction corresponding to the arrow B in FIG.

  When the SMA 107 is not energized, as shown in FIG. 7A, the objective lens holder 102 maintains a horizontal posture.

  When the SMA 107 is energized, the SMA 107 contracts to a predetermined length according to the amount of current. As shown in FIG. 7B, the wire fixing portion 103a on which the SMA 107 is installed receives a force in the direction of the arrow Y1, It pivots slightly counterclockwise in FIG. 7B around the hinge 104. By the slight rotation of the wire fixing portion 103a, the wire is elastically deformed and stops in a state where the forces of the four wires 105a to 105d are balanced. In this state, the objective lens holder 102 is slightly tilted counterclockwise in FIG. In this way, the objective lens holder 102 can be made to perform a tangential tilt operation. Thus, the SMA 107 and the hinge 104 function as wire displacement means in the present invention.

[Embodiment 6]
FIG. 8 shows the configuration of the optical pickup according to the sixth embodiment. FIG. 8 is a view showing a tilt mechanism of the optical pickup 1 according to the sixth embodiment viewed from the direction corresponding to the arrow A2 in FIG. The optical pickup 1 according to Embodiment 6 causes the objective lens holder 102 to perform a tangential tilt operation and a radial tilt operation.

  Hinges 104a and 104b for elastic deformation are provided on the left and right of the upper part of the wire fixing part 103, and the wire fixing parts 103a and 103b for fixing the two wires 105a and 105b are respectively moved in the directions of arrows P and Q by the hinges 104a and 104b. It is supported so as to be capable of minute rotation.

  The SMAs 107a and 107b hooked on the two wires 105a and 105b are expanded and contracted to a predetermined length by a current supplied from a drive / control circuit (not shown) via the terminals 108a and 108b. The lens holder 102 is made to perform a tangential tilt operation and a radial tilt operation.

  FIG. 9 shows a state where the SMAs 107a and 107b are energized so as to contract to the same length. The wire fixing portions 103a and 103b of the wires 105a and 105b receive a force in the direction of the arrow Y1 by the SMAs 107a and 107b, respectively, and slightly rotate in the directions of the arrows R1 and R2. The state of the objective lens holder 102 at this time is shown in FIG. FIG. 10 is a schematic diagram showing a tangential tilt operation when viewed from the direction corresponding to the arrow B in FIG.

  As the portions of the two wires 105a and 105b adjacent to the fixing portions 103a and 103b move in the Y1 direction, the four wires 105a to 105b are slightly tilted clockwise in FIG. 10 due to force balance. . Thereby, the objective lens holder 102 can be made to perform a tangential tilt operation.

  Next, FIG. 11 shows a state where only the SMA 107b is energized. The wire fixing portion 103b of the wire 105b receives a force in the arrow Y1 direction by the SMA 107b and slightly rotates in the arrow R2 direction. In this case, the objective lens holder 102 performs exactly the same operation as that shown in FIG. That is, a radial tilt operation is performed.

  As described above, the optical pickup 1 according to the sixth embodiment can cause the objective lens holder 102 to perform a radial tilt operation or a tangential tilt operation by selecting a wire to be energized. Note that the SMAs 107a and 107b and the hinges 104a and 104b function as wire displacement means in the present invention.

  Further, the radial tilt operation and the tangential tilt operation can be simultaneously performed by adjusting the energization amount to the SMAs 107a and 107b.

  Although only the tilting operation in the direction in which the SMA contracts has been described, the bias spring 109 is provided, and the operation in the direction in which the SMA extends can be achieved by balancing the forces of the SMA and the bias spring 109.

  Thus, in the embodiment of the present invention, the wire displacing means (SMA 107, bias spring 109, lever 110, hinge 104) is attached to the support member (wire fixing portion 103) of the wire 105 coupled to the objective lens holder 102. The objective lens holder 102 is tilted by minutely displacing the adjacent portion. Since the portion of the wire 105 close to the support member is displaced, the objective lens holder 102 can be tilted with a large amplitude with a slight displacement. In addition, it is possible to suppress the influence of the tilt operation on the focus and tracking operations. Thereby, a highly accurate tilt operation (tilt correction operation) can be easily performed with a simple configuration.

  The present invention has been described above with reference to the embodiments. However, the present invention should not be construed as being limited to the above-described embodiments, and can be changed or improved as appropriate. For example, in the above-described embodiment, the optical pickup is used as an example, and the lens is arranged in the driven portion. However, the driven body may be an optical element such as a reflection mirror or a detection device such as a position sensor. .

1 is a diagram illustrating a schematic configuration of an optical pickup according to Embodiment 1. FIG. FIG. 5 is a schematic diagram illustrating a radial tilt operation of the optical pickup according to the first embodiment. FIG. 6 is a diagram illustrating a radial tilt mechanism of an optical pickup according to a second embodiment. FIG. 10 is a diagram illustrating a radial tilt mechanism of an optical pickup according to a third embodiment. FIG. 10 is a diagram illustrating a radial tilt tilt mechanism of an optical pickup according to a fourth embodiment. FIG. 10 is a diagram illustrating a tangential tilt mechanism of an optical pickup according to a fifth embodiment. FIG. 10 is a schematic diagram for explaining a tangential tilt operation of an optical pickup according to a fifth embodiment. FIG. 10 shows a tilt mechanism of an optical pickup according to a sixth embodiment. FIG. 10 is a schematic diagram illustrating an example of a tilt operation of an optical pickup according to a sixth embodiment. It is the schematic diagram which looked at the tilting operation shown in FIG. 9 from the side. FIG. 16 is a schematic diagram for explaining another example of the tilt operation of the optical pickup according to the sixth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical pick-up 101 Objective lens 102 Objective lens holder 103 Wire fixing part 104 Hinge 105 Wire 107 SMA
108 Terminal 109 Bias spring 110 Lever 111 Rotating shaft 115 Insulating collar 130 Base

Claims (8)

In an optical pickup that reads and writes information on an optical disc and performs focus and tracking operations.
An objective lens for condensing light on the optical disc;
An objective lens holder for holding the objective lens;
A plurality of wires having one end coupled to the objective lens holder;
A support member that is coupled to the other ends of the plurality of wires and rotatably supports the lens holder via the plurality of wires;
An optical pickup comprising: a wire displacing means for tilting the objective lens holder by minutely displacing a portion of the wire adjacent to the support member. The wire displacing means causes the objective lens holder to move in a direction perpendicular to both the focus direction and the tracking direction by minutely displacing at least two portions of the wire adjacent to the support member in different directions. The optical pickup according to claim 1, wherein the optical pickup is rotated as follows. The wire displacement means is
A lever member on which at least two wires are hooked and rotatably supported;
The optical pickup according to claim 2, further comprising: a drive source that causes the lever member to rotate slightly. The wire displacing means rotates the objective lens holder about a tracking direction by minutely displacing at least two portions of the wire adjacent to the support member in the same direction. The optical pickup according to 1. The support member includes a first support member to which at least two of the wires are coupled, and a second support member to which the other wires are coupled,
The wire displacement means is
A hinge portion for rotatably supporting the first support member;
The optical pickup according to claim 4, further comprising: a driving source that minutely rotates the first support member. The wire displacing means selectively displaces the portion of the at least two wires adjacent to the support member by minute displacement, thereby moving the objective lens holder in a direction perpendicular to both the focus direction and the tracking direction and the tracking direction. The optical pickup according to claim 1, wherein the optical pickup is rotated about an axis in one of the directions. The optical pickup according to claim 1, wherein the wire displacement means includes a shape memory alloy. A driven part which is a driven object;
A wire having one end coupled to the driven portion;
A support member that is coupled to the other end of the wire and movably supports the driven part via the wire;
A drive device comprising: drive means for driving the driven portion by minutely displacing a portion of the wire adjacent to the support member.

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