JP2503401Y2 - Objective lens drive - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to recording in an optical disc player or the like by irradiating a light beam on an optical disc storing information signals such as audio signals and video signals to read or write the information signals. And / or an objective lens driving device used for an optical pickup device of a reproducing device.

[Conventional technology]

2. Description of the Related Art Conventionally, an optical pickup device used in an optical disc player accurately tracks a recording track of an optical disc that is rotated at a high speed by a light beam emitted from a laser oscillator such as a semiconductor laser. An objective lens driving device is provided for performing tracking control and focus control by drivingly displacing the objective lens for focusing on the recording track in the biaxial directions orthogonal to each other in the tracking direction and the focus direction of the recording track.

As an objective lens driving device of this type, there is known one configured as shown in FIG. This objective lens driving device supports the objective lens 1 and
The bobbin 2 is provided with a drive coil which constitutes an electromagnetic drive means for driving and displacing the element in a direction parallel to the optical axis direction and a direction orthogonal to the optical axis direction. And bobbin 2
Two planes orthogonal to the optical axis direction are formed by parallel springs 4 and 4 made up of a pair of leaf springs whose base ends are attached to a support body 3 movably supported in a direction orthogonal to the optical axis direction of the objective lens 1. In the figure, it is cantilevered so as to hold the upper and lower two surfaces. In the objective lens driving device configured as described above, when the driving force in the optical axis direction of the objective lens 1 is applied to the bobbin 2 by the electromagnetic driving means, the parallel springs 4 and 4 are elastically displaced and the objective is moved. The lens 1 is moved and displaced parallel to the direction of the arrow in FIG. 9, and focus control of the light beam focused on the signal recording surface of the optical disc is performed.

[Problems to be solved by the device]

In the objective lens driving device configured as described above, since the parallel springs 4 and 4 supporting the objective lens 1 are formed of leaf springs, the minimum resonance frequency f ₀ and the minimum resonance frequency f of the parallel springs 4 and 4 are The resonance sharpness (Q value) at the ₀ point depends on the material and the plate thickness of the leaf spring. However, the leaf spring formed of a sheet metal has large variations in the sheet thickness due to the material and processing characteristics, and the minimum resonance frequency f ₀ and the resonance sharpness (Q value) are not constant. Therefore, it is difficult to perform stable drive control of the objective lens 1 according to the control drive current in the tracking and focus directions.

In particular, in the case of using the metal leaf springs for the parallel springs 4 and 4, the lowest resonance frequency f ₀ of the leaf spring is high, and the resonance sharpness (Q value) at the lowest resonance frequency f ₀ point becomes large. I will end up. In particular, in the objective lens driving device that requires fine control of the tracking direction and the focus direction, the control driving frequency is also high, and high-order resonance is likely to occur during driving.
The objective lens 1 cannot be controlled with good control characteristics that follow the control drive currents in the tracking and focus directions.

To prevent such higher-order resonance and obtain stable control characteristics, lower the minimum resonance frequency f ₀
It is necessary to reduce the resonance sharpness (Q value) at the point f ₀ .

Therefore, in the conventional objective lens driving device, a member having a large viscous resistance such as rubber is adhered to the parallel springs 4 and 4 formed of sheet metal leaf springs to lower the minimum resonance frequency f _{0 and} to reduce the resonance sharpness (Q Value) is made small. However, even with this type, the resonance sharpness (Q value) is sufficient.
In addition to being unable to reduce the size, it is difficult to achieve stabilization of the control characteristics of the objective lens due to the influence of the adhesive agent for joining the rubber or the like and the variation in the hardness of the joined rubber or the like.

Therefore, the present invention can easily control the minimum resonance frequency f ₀ of the member supporting the objective lens,
Resonance sharpness (Q value) is reduced to suppress the occurrence of higher resonance,
An object of the present invention is to provide an objective lens driving device capable of performing stable driving control of the objective lens.

Another object of the present invention is to provide an objective lens driving device that is easy to assemble and can be easily mass-produced.

[Means for solving the problem]

The objective lens driving device according to the present invention is provided with a holding portion for holding the objective lens on the free end side in order to solve the problems of the conventional device described above and to achieve the above object. In addition, a pair of first arms having first and second elastic displacement portions that are movable in a direction parallel to the optical axis of the objective lens, and a mounting portion on the fixed end side are provided, and the objective lens is provided. A pair of second arms that are displaceable in a direction orthogonal to the optical axis and that are formed with third and fourth elastic displacement portions formed in a direction orthogonal to the first and second elastic displacement portions, An objective lens support member integrally formed of a synthetic resin with a connecting member that connects the other end sides of the first and second arms, and a free end side on which the holding portion of the objective lens support member is formed. The objective lens Those constructed an electromagnetic driving means for driving the displacement in the direction perpendicular to the direction parallel to the axis and the optical axis.

[Action]

According to the present invention, an objective lens supporting member, which holds an objective lens and is provided with a plurality of elastic displacement portions for movably supporting the objective lens in an optical axis direction and a direction orthogonal to the optical axis, is integrally formed of synthetic resin. Therefore, by selecting the synthetic resin material to be used and adjusting the elastic displacement force of the elastic displacement portion, the minimum resonance frequency f ₀ can be controlled and the resonance sharpness (Q value) can be reduced.

Further, when a driving force for driving and displacing the objective lens in a direction parallel to the optical axis and a direction orthogonal to the optical axis is applied by the electromagnetic driving means, the pair of first arms holding the objective lens causes the first and second arms to move. The elastically displacing portion 2 is elastically deformed to move and displace the objective lens in the optical axis direction, and
The arm elastically deforms the third and fourth elastic displacement portions to move and displace in the direction parallel to the direction orthogonal to the optical axis.

〔Example〕

Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the objective lens driving device 13 according to the present invention comprises a semiconductor laser that emits a light beam, a light beam emitted from the semiconductor laser and applied to an optical disc, and a return beam reflected from the optical disc. The optical pickup device is arranged on an optical system block 11 including an optical component such as a beam splitter for separating light and a photodetector for detecting a return beam, and constitutes an optical pickup device used for an optical disc player or the like.

This objective lens driving device includes an objective lens 12 for condensing a light beam on a signal recording surface of an optical disc, and an optical axis of the objective lens 12 according to an error detection output in a focus direction and a tracking direction obtained by detecting a return beam. The focus control and the tracking control of the light beam are performed by driving and displacing in the focus direction of the direction and the tracking direction orthogonal to the optical axis direction. As shown in FIG. 2, the objective lens driving device 13 is a magnetic circuit including first and second U-shaped yokes 14 and 15 and magnets 16 and 16 attached to the yokes 14 and 15. Section and the return beam reflected from the signal recording surface of the optical disc, a control drive current corresponding to the error detection output in the focus direction and the tracking direction obtained by detecting the return beam is supplied to the objective lens 12 in the optical axis direction and the optical axis direction. A focus drive coil 17 and four tracking drive coils 18, which form an electromagnetic drive unit together with a magnetic circuit unit that generates a drive force for driving in a direction orthogonal to the drive coil 17, and these drive coils 17, 18 are attached. The rectangular bobbin 19 and the objective lens 12 which support the objective lens 12 so as to be movable and displaceable in the optical axis direction and the direction orthogonal to the optical axis direction, and which is made of a synthetic resin to which the bobbin 19 is attached. Lens support member 20.

First and second yokes 14 and 15 constituting the magnetic circuit section
Is an optical system block 11 in which the open side is symmetrically directed upward with respect to the optical window 10 through which the light beam provided in the optical system block 11 passes, and the rising pieces 14a, 14b and 15a, 15b face each other.
It is positioned and mounted on the upper surface of. The magnets 16 and 16 are joined and arranged on the inner side surfaces of the rising pieces 14a and 15a located on the outer sides of the first and second yokes 14 and 15, respectively.

Further, the focus driving coil 17 generates a driving force for driving the objective lens 12 in the focus direction which is the optical axis direction in cooperation with the magnetizing directions of the magnets 16 and 16 when the control driving current is supplied. It is wound around the bobbin 19 in the circumferential direction. Each tracking drive coil 18 drives to drive the objective lens 12 in a tracking direction which is a direction orthogonal to the optical axis direction in cooperation with the magnetizing directions of the magnets 16 and 16 when a control drive current is also supplied. It is wound in a rectangular shape so as to generate force, and is provided over each corner portion of the bobbin 19.

Further, the objective lens supporting member 20 is integrally formed as shown in FIG. 3 by molding a synthetic resin such as polypropylene or polyester elastomer which is resistant to bending fatigue. This objective lens supporting member 20 is capable of displacing the objective lens 12 and the bobbin 19 in the optical axis direction of the objective lens 12 on both upper and lower sides of a connecting portion 21 having a height H ₂ which is substantially the same as the height H ₁ of the bobbin 19. A pair of support arms 23 and 24 forming the parallel arm 22 to be supported are connected in series via first elastic displacement portions 25 and 26 as shown in FIG. 3 (A). These elastic displacement portions 25, 26 are formed by forming the connecting portions of the support arms 23, 24 to the connecting portion 21 as thin portions. Further, cutout holes 27, 28 are provided in the continuous portion to adjust the elastic displacement force of the elastic displacement portions 25, 26 of FIG. The pair of support arms 23 and 24 are
As shown in FIG. 3 (B), the parallel arms 22 are bent parallel to the opposite sides along the first elastic displacement portions 25, 26.
Is configured. An objective lens attachment hole 30 into which a lens holder 29 to which the objective lens 12 is attached is fitted is formed on the free end side of one of the pair of support arms 23 and 24 forming the parallel arm 22. Installed on the other arm
A beam transmission hole 31 for controlling the light beam incident on the objective lens 12 is formed on the free end side of 24. Further, when the objective lens support member 20 is attached to the optical system block 11 on the pair of support arms 23, 24, the first and second yokes 1
Inward rising piece 14 facing the magnets 16 and 16 of 4,15
Yoke insertion holes 32, 33, 34, and 35 through which b and 15b are respectively inserted are symmetrically formed around the objective lens attachment hole 30 and the beam transmission hole 31. Furthermore, a pair of support arms 23, 24
As shown in FIGS. 3A and 3B, both ends of the bobbin 19 are positioned and engaged with the inner surfaces of the bobbin 19 centering on the centers of the objective lens mounting hole 30 and the beam transmitting hole 31. Joint portions 36 and 37 are provided.

Then, in the objective lens 12, the lens holder 29 having the objective lens 12 attached is fitted into the objective lens attachment hole 30 of the one support arm 23, and the flange portion 29 of the lens holder 29.
The a is attached to one of the support arms 23 so that the optical axis thereof is orthogonal. In addition, the bobbin 19 includes the engagement step portions 36, 37 of the pair of support arms 23, 24 that are bent so as to be parallel to each other.
Both ends are engaged with each other, and both end surfaces are joined with an adhesive so that they are sandwiched between the pair of support arms 23 and 24.

As described above, when the parallel arm 22 including the pair of support arms 23 and 24 that supports the objective lens 12 and the bobbin 19 receives the driving force in the focus direction, the objective lens 12 has the first elastic displacement in the optical axis direction. Second elastic displacement portions 38, 39 are provided in the width direction in the middle of the first and second support arms 23, 24 so as to be able to move in parallel with the portions 25, 26. There is. These second elastic displacement portions 38, 39 are formed by forming a part of the pair of support arms 23, 24 as thin portions like the first elastic displacement portions 25, 26, and the elastic displacement force is formed in the central portion. Notch holes 40 and 41 for adjusting the are provided.

In addition, a pair of support arms 2 forming a first parallel arm 22 is provided on both left and right sides of the connecting portion 21 of the objective lens support member 20.
Objective lens 12 and bobbin 19 are orthogonal to 3, 24
A pair of fixed arms 43 and 44, which are movably supported in the direction orthogonal to the optical axis direction of 12 and serve as a fixed portion to the optical system block 11, are provided in series. These fixed arms 43,44 also
As shown in FIG. 3 (A), it is connected to the connecting portion 21 via the third elastic displacement portions 45, 46. These elastic displacement parts 45,4
6 is also formed by forming a thin portion in the connecting portion to the connecting portion 21, and notch holes 47 and 48 for adjusting the elastic displacement force are provided in the connecting portion. Then, the pair of fixed arms 43 and 44 are bent along the third elastic displacement portions 45 and 46 so as to face each other and be parallel to each other, as shown in FIG. 3C. The pair of fixed arms 43 and 44 are formed in the same shape with left-right symmetry, and an optical system block 11 serving as a fixed portion at one end.
Mounting portions 49 and 50 are provided. These mounting parts 4
9,50 is formed by bulging one end of the fixed arms 43,44,
The screw insertion holes 53 and 54 are formed by inserting the fixing screws 51 and 52 in the axial direction. Furthermore, a pair of fixed arms 4
When the driving force in the tracking direction is received, the objective lens 12 mounted via the parallel arm 22 is provided in the middle of 3,44.
And a fourth elastic displacement portion 55 across the width direction so that the bobbin 19 can move in parallel with the third elastic displacement portions 45 and 46 in a direction orthogonal to the optical axis direction of the objective lens 12. 56 are provided. These fourth elastic displacement portions 55 and 56 are formed by forming a part of the pair of fixed arms 43 and 44 into thin-walled portions, similarly to the second elastic displacement portions 38 and 39, and are elastically displaced in the central portion. Notched holes 57 and 58 for adjusting force are provided.

As described above, the parallel lens supporting the objective lens and the bobbin 19 and the pair of fixed arms 43 and 44 are integrally provided, and the objective lens supporting member 20 includes the optical axis of the objective lens 12 and the optical window 10 of the optical system block 11. The optical axis of the light beam that transmits the light beam is aligned with the optical axis of the optical system block 11 as shown in FIG. That is, in the objective lens supporting member 20, the mounting portions 49, 50 provided at one end of the fixed arms 43, 44 are fixed to the optical system block 11 serving as the mounting base by the fixing screws 51, 53 with the spacer 59 interposed. Installed by doing. At this time, in the yoke insertion holes 32, 33, 34, 35 formed in the parallel arm 22, the rising pieces 14b, 15b on the inner side of the first and second yokes 14, 15 are shown in FIG. To insert.
The focus and mounting drive coils 17 and 18 mounted on the bobbin 19 are attached to the magnets 16 and 16 and the first and second yokes.
It is supported by holding a predetermined magnetic gap in the gap between 14 and 15.

The objective lens drive device 13 of the optical pickup device configured as described above supplies the focus drive current to the focus drive coil 17 according to the error detection output in the focus direction obtained by detecting the return beam reflected from the optical disc. Then, due to the magnetic action, a driving force in the direction of arrow F in FIG. 4 is generated on the bobbin 19 from the current flowing through the coil 17 and the direction of the magnetic field of the magnets 16, 16. In the parallel arm 22 to which the bobbin 19 having received this driving force is attached, the first and second elastic displacement portions 25, 26 and 38, 39 are elastically displaced, and the objective lens is displaced and driven in the arrow F direction in FIG. Focus control is performed by displacing 12 in the optical axis direction. At this time, the parallel arm 22
Is the first and second elastic displacement parts 25, 26 and 3 which are parallel to each other.
Since 8,39 is elastically displaced with respect to the bending point, the distal end side is moved and displaced while maintaining the parallel state, and the objective lens 12 is also approximately linearly moved in the optical axis direction.

Further, when a tracking drive current corresponding to the error detection output in the tracking direction obtained by detecting the return beam reflected from the optical disk is supplied to each tracking drive coil 18, the current flowing through the coil 18 and the magnet due to the magnetic action. A driving force in the direction of arrow T in FIG. 6 is generated on the bobbin 19 from the directions of the magnetic fields 16 and 16. Then, by this driving force, the first and second elastic displacement portions 25, 26 and 38, 39
Third elastic displacement portions 45, 4 formed in a direction orthogonal to
6 elastically displaces, and the fourth elastic displacement parts 55, 56 formed in the middle of the pair of fixed arms 43, 44 elastically displace,
The objective lens 12 is displaced and driven in the direction orthogonal to the optical axis in the direction of arrow T in FIG. 6 to perform tracking control of the light beam. At this time, the pair of fixed arms 43, 44 elastically displaces with the third and fourth elastic displacement portions 45, 46 and 55, 56 parallel to each other as bending points, so that the objective lens including the parallel arm 22 is included.
12 and the bobbin 19 are translated while maintaining a horizontal state with respect to the optical system block 11.

Furthermore, in the above description, the pair of fixed arms 43, 4
Although 4 is bent in parallel, by appropriately selecting the fixing position to the optical system block 11, even if it is bent so as to expand slightly, the third and fourth If the elastic displacement portions 45, 46 and 55, 56 are parallel to each other, the objective lens 12 including the parallel arm 22 and the bobbin 19 are horizontally displaced relative to the optical system block 11.

In the above-described embodiment, the objective lens support member 20 is directly attached to the optical system block 11 to form the optical pickup device. However, as shown in FIGS. Optical system block as a base via
May be attached to 11. In the case of this example, the first and second yokes 14 and 15 to which the magnets 16 and 16 constituting the magnetic circuit section are attached are attached to the attachment substrate 61.

Further, the objective lens supporting member 20 supporting the objective lens 12 and the bobbin 19 has mounting portions 64 and 65 in which mounting portions 62 and 63 provided at one end of the pair of fixed arms 43 and 44 are formed on both sides of the mounting substrate 61. Fix it with screws 66 and install it.
In this case, the mounting portion 62 provided on one fixed arm 43
Is a positioning protrusion provided on the screw hole 67 and one mounting piece 64.
A positioning hole that fits into the arm 68 is provided horizontally in the longitudinal direction of the arm 43. Further, the mounting portion 63 provided on the other fixed arm 44 has a positioning hole 72 that fits into the screw hole 70 and the positioning protrusion 71 provided on the other mounting piece 65.
It is provided vertically to the height direction of the. Then, the objective lens supporting member 20 fits the positioning holes 72 of the mounting portions 62, 63 provided on the pair of fixed arms 43, 44 to the respective mounting protrusions 68, 71 on the respective mounting pieces 64, 65, and with the screw 66. It is fixed and positioned and attached without being displaced with respect to the driving force applied to the optical axis direction of the objective lens 12 and the direction orthogonal to the optical axis direction.

As described above, the mounting substrate to which the objective lens supporting member 20 is mounted has the fitting cylindrical portion 74 which also allows the light beam to pass through in which the fitting hole 73 through which the light beam passes is provided in the optical system block 11.
It is fitted to and fixed by a screw 75.

In the embodiment described above, the bobbin 19 is formed separately from the objective lens support member 20, but it is integrally provided on the inner surface side of either one of the support arms 23 and 24 forming the parallel arm 22. You may do it.

[Effect of device]

As described above, the objective lens driving device according to the present invention is provided with a plurality of elastic displacement portions for holding the objective lens and movably supporting the objective lens in the optical axis direction and the direction orthogonal to the optical axis. Since the lens support member is integrally formed of synthetic resin, the elastic displacement force of each elastic displacement portion is adjusted when the objective lens is moved and displaced by the electromagnetic drive means in the optical axis direction and the direction orthogonal to the optical axis direction. Can be easily performed by adjusting the thickness of each elastic displacement portion.

And with the adjustment of the elastic displacement force of each elastic displacement part,
By appropriately selecting the synthetic resin material that constitutes the support member for the objective lens, the minimum resonance frequency f of each arm is controlled according to the frequency of the control current for driving and controlling the objective lens, and the resonance sharpness (Q value) is controlled. It is not small, and it is possible to easily realize the occurrence of resonance during driving.

Further, since the objective lens support member is integrally formed of synthetic resin and the objective lens is supported by the cantilever support structure, the objective lens is orthogonal to the optical axis direction by the electromagnetic drive means. When moving and displacing in one direction, variations in displacement characteristics in each direction can be reduced, and stable drive control of the objective lens is realized.
That is, since the objective lens is supported by the cantilever support structure by the objective lens support member integrally formed of synthetic resin, the objective lens is less likely to be tilted in the optical axis direction at the time of driving displacement and is small in size. You can

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment in which the objective lens driving device according to the present invention is suitable for an optical pickup device.
FIG. 3 is a perspective view showing the objective lens driving device in an exploded manner, FIG. 3 shows an objective lens supporting member, FIG. 3 (A) is an exploded view thereof, and FIG. 3 is a sectional view taken along line AA of FIG. 3 (A), FIG. 3 (C) is a sectional view taken along line BB of FIG. 3 (A), and FIG. 4 is a side view of the objective lens driving device. 5 is a sectional view thereof, and FIG. 6 is a plan view thereof. FIG. 7 is a perspective view showing another embodiment of the present invention.
The figure is an exploded perspective view thereof. FIG. 9 is a schematic perspective view showing a conventional objective lens driving device. 11 …… Optical system block 12 …… Objective lens 16 …… Magnet 17 …… Focus drive coil 18 …… Tracking drive coil 19 …… Bobbin 23,24 …… Support arm 25,26 …… First elastic displacement part 30 …… Objective lens mounting hole 38,39 …… Second elastic displacement part 45,46 …… Third elastic displacement part 49,50 …… Mounting part

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Toru Fujimori 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation (56) References JP-A-58-182141 (JP, A) 58-179661 (JP, U)

Claims (1)

(57) [Scope of utility model registration request] 1. A pair of first and second elastic displacement portions, each of which has a holding portion for holding an objective lens on its free end side and is movable in a direction parallel to an optical axis of the objective lens. A first arm, a mounting portion on the fixed end side, a third arm that is displaceable in a direction orthogonal to the optical axis of the objective lens, and is formed in a direction orthogonal to the first and second elastic displacement portions. And an objective lens support in which a pair of second arms having a fourth elastic displacement portion and a connecting member for connecting the other ends of the first and second arms are integrally formed of synthetic resin. A member, and an electromagnetic driving means which is disposed on the free end side of the objective lens supporting member on which the holding portion is formed and which drives and displaces the objective lens in a direction parallel to the optical axis and a direction orthogonal to the optical axis. An objective characterized by comprising Lens driving device.