JPH08180422A - Method for adjusting position of objective lens - Google Patents

Abstract

PURPOSE: To provide a method for adjusting the position of an objective lens capable of reducing the time and labor for adjusting the position, capable of making an adjusting device compact, high in accuracy and wide in application range. CONSTITUTION: In an objective lens driving device of optical pickup, a supporting member 21 consisting of a shape memory material is provided between the objective lens 6 and an objective lens holder 6a, and the objective lens 6 is supported only by the supporting member 21 for objective lens. The thermal energy is applied partially to the supporting member 21 by a laser beam from the outside to restore the shape of this part, then the supporting member 21 is minutely deformed by the internal stress generated between this part and surrounding part thereof, and the inclination and height of the objective lens 6 are thereby adjusted. Thus, the inclination and height are silmultaneously adjusted without touching the objective lens 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position adjusting method for adjusting an optical axis of an objective lens with respect to an optical axis from a light source.
Specifically, for example, the optical axis of an objective lens included in an optical pickup device used for irradiating an optical disk with laser light to record, reproduce, and erase information on the optical disk is an objective with respect to an optical axis from a laser light source. The present invention relates to a method for adjusting the position of an objective lens, in which the optical axis of the objective lens and the optical axis of the laser light source can be made parallel by adjusting the inclination of the lens. Further, the present invention relates to a method of adjusting the position of the objective lens, which can adjust the height (position in the optical axis direction) of the objective lens and can absorb the assembly error in the focus direction of the actuator included in the optical pickup device.

[0002]

2. Description of the Related Art FIG. 5 shows a side view of a magneto-optical disk device. In this magneto-optical disk device, a magneto-optical disk 51 is rotationally driven by a motor 52. Then, the laser light 57 emitted from the laser light source 53a is reflected by the mirror 53b, and then passes through the objective lens 56 to be included in the disc recording medium 51a built in the magneto-optical disc 51.
It converges on the surface of and records, reproduces, or erases information.

The objective lens driving device 54 includes an objective lens 5
6 is moved up, down, left and right so that the converged position of the laser beam 57 follows the recording track of the disk recording medium 51a. The housing 53 accommodates an optical system such as a laser light source 53a and a mirror 53b, and the housing 53 and the objective lens driving device 54.
And constitute an optical pickup device (optical head). The electromagnet coil 55 records and erases information by a magnetic field.

In the above magneto-optical disk device, when the objective lens 56 is attached so as to be tilted with respect to the optical axis 57a, the laser light traveling from the objective lens 56 to the magneto-optical disk 51 suffers aberrations, and the laser light 57 is sufficient. The result is that the information on adjacent tracks does not converge to crosstalk and causes crosstalk.

Therefore, conventionally, in order to solve the above-mentioned problem, a spacer 58 is provided between the objective lens driving device 54 and the housing 53, and the objective lens 56 has an optical axis 57a.
I was adjusting so that I wouldn't lean against.

In another conventional example, as shown in FIG. 6, a spherical seat 69a is provided on the upper surface of the housing 63, a spherical projection 69b is provided on the bottom of the objective lens driving device 64, and screws 70a, 70b and objectives are provided. A coil spring 71 is provided between the lens driving device 64 and the fixing screws 70c and 70d so that the objective lens 66 does not tilt with respect to the optical axis from the light source. In some cases, instead of completely tightening the fixing screws 70c and 70d, an adhesive is injected into the spherical seat 69a.

The third conventional example is different from the above-mentioned two conventional examples in which the tilt of the entire objective lens driving device is adjusted, and the objective lens itself is bonded after the tilt angle is adjusted by the tilt adjusting device. Then, there is one that is fixed (see Japanese Patent Laid-Open No. 04-113521).

[0008]

However, in the former objective lens tilt adjusting method described with reference to FIG.
Since it is not possible to simultaneously perform the work of measuring the tilt and the work of tilting, there is a problem that it takes time to adjust the tilt. Further, since the work of inserting the spacer 58 must repeat the screw tightening work and the screw removing work, there is a problem that it takes time.

Further, in the latter objective lens tilt adjusting method described with reference to FIG. 6, since the spherical seat 69a occupies a space, the height dimension 72 is required, which is disadvantageous in thinning the adjusting device. There's a problem.

A third conventional example, Japanese Patent Laid-Open No.
In the method described in Japanese Patent No. 4-1113521,
Since the tilt adjusting device tilts the objective lens itself, the structure supporting the objective lens is a movable body.
Then, the movable body is adjusted from the outside. Therefore, in the third conventional example, there is a problem that the measurement is difficult because the beam spot being observed moves due to the movement of the support structure with a slight external force.

By the way, the movable range in the focus direction (height direction) of the actuator of the objective lens is determined by
This is mainly due to the amount of surface vibration of the disk and the assembly error in the focus direction (height direction) of the actuator, pickup, etc. Therefore, the movable range in the focus direction (height direction) of the actuator can be reduced by adjusting the height of the objective lens and eliminating the above assembly error, so that the actuator can be designed in a small size. Therefore,
In particular, it is advantageous in downsizing of the optical disk device in terms of the device thickness.

In order to realize this downsizing, in the former and latter conventional examples, it is necessary to provide an objective lens height adjusting mechanism in addition to the tilt adjusting mechanism.

That is, the height of the reference surface of the turntable on the spindle motor for mounting the disk and the focal position of the objective lens are measured to find the assembly error of the actuator, the pickup, etc., and the former conventional example corresponds to the above error. In the latter conventional example, a height adjusting mechanism of a turntable that applies a screw is provided in the spindle motor mount portion to absorb the error. However, as described above, the former work of interposing the spacer requires the screw tightening work and the screw removing work to be repeated, which causes a problem that it takes time. Further, the latter method of adjusting the height of a spindle motor using screws has a drawback that it cannot be effectively applied only to a spindle motor having a special structure in which a motor shaft makes a metal contact with a base or the like. Furthermore, it is not impossible to say that adjustment with screws is not easy when aiming to automate the adjustment work. Further, in the method of fixing the lens with the resin after adjusting the position of the objective lens, the posture shift occurs due to the curing shrinkage of the resin, which limits the accuracy setting.

Therefore, an object of the present invention is to provide a method for adjusting the position of an objective lens, which can reduce the time and labor for position adjustment, can make the adjusting device compact, and have high precision and a wide range of application. Especially.

[0015]

In order to achieve the above object, a position adjusting method of an objective lens according to the invention of claim 1 is such that a shape memory is provided between an objective lens and an objective lens holder for holding the objective lens. A support member made of a material having an effect is provided, the support lens supports the objective lens with respect to the objective lens holder, and the support member is partially heated to a shape recovery temperature or higher to locally The shape of the objective lens is adjusted with respect to the optical axis from the light source by generating internal stress in the support member by deforming the support member and deforming the support member. .

According to a second aspect of the present invention, in the method for adjusting the position of the objective lens according to the first aspect, the supporting member supports three or more positions in the circumferential direction of the objective lens, and the supporting member is locally supported. It is characterized in that the tilt angle of the optical axis of the objective lens with respect to the optical axis from the light source and the position of the objective lens in the optical axis direction are adjusted by recovering the shape.

The invention according to claim 3 is the method for adjusting the position of an objective lens according to claim 1 or 2, characterized in that the support member is made of a shape memory alloy.

Further, the invention of claim 4 relates to claims 1 to 3.
In the method for adjusting a position of an objective lens according to any one of 1, a laser is irradiated locally on the support member made of a material having a shape memory effect to locally recover the shape of the support member. The feature is that the optical axis of the objective lens is adjusted with respect to the optical axis from the light source.

[0019]

According to the invention of claim 1, as described above, a part or all of the supporting member for supporting the objective lens is made of a shape memory material, and the invention of claim 2 is as described above. Part or all of the three or more supporting members for mounting the lenses are made of a shape memory material. Then, the support member is displaced by heating the local portion of the shape memory material to a temperature higher than the shape recovery temperature, and as a result, the height of the support point of the objective lens arranged thereon changes, and the objective lens is aligned with the optical axis. The height of the objective lens can be adjusted so that the assembly error of the focus direction of the actuator / pickup and the like can be absorbed at the same time as well as tilting the lens.

Even if the shape memory material is plastically deformed below the shape recovery temperature after being subjected to the shape memory treatment, it is restored to its original memorized shape when heated above the shape recovery temperature. It is a basic concept of the adjusting mechanism that the supporting member is gradually displaced by partially utilizing this shape recovery force by local heating, and as a result, the posture of the objective lens installed thereon is adjusted.

Hereinafter, this concept will be described in more detail.

The shape memory effect is a phenomenon that accompanies, for example, a metal, which is called a thermoelastic type martensitic transformation (hereinafter abbreviated as M transformation), and the M transformation is a crystal structure in a solid phase. It is a type of phase transformation that changes the phase, and is a phase transformation that occurs like shear deformation while the atoms as a whole maintain coordination without diffusion of the atoms over a long distance. This M transformation is caused by a change in temperature, and the temperature at which the phase transformation occurs is called the transformation temperature or transformation point. Phase (hereinafter abbreviated as M phase). Since the crystal structure of the alloy is different between the A phase and the M phase, the characteristics also change in various ways. When the shape memory alloy in the A phase state on the high temperature side is cooled, it undergoes M transformation to become the M phase, and when the M phase shape memory alloy is heated, it undergoes reverse transformation and returns to the A phase.

Conventionally, shape memory alloys have a temperature higher than the temperature at which the reverse transformation of the entire material is completed (hereinafter abbreviated as Af point), even if plastic deformation is applied below the temperature at which M transformation usually starts (hereinafter abbreviated as Ms point). It was generally applied in the form of utilizing the phase change of the entire material, that is, the material returns to its original shape when heated up to. Alternatively, as in the case of an eyeglass frame or an antenna of a mobile phone, it is common to use the property of superelasticity in the phase A, which immediately returns to its original shape even if it is deformed.

On the other hand, the present invention intends to utilize the new shape memory effect as described above.

FIG. 7 shows the basic concept of the member position adjusting method of the present invention. As shown in FIG. 7, first, (A) the entire adjusting portion of the member is subjected to heat treatment for shape memory to store a predetermined first shape, and (B) the entire adjusting portion is subjected to Ms.
If desired plastic deformation is applied below the point, and (C) after that, local heating is performed (for example, by irradiating with a laser) so that a part of the adjusting portion is above the Af point,
In this heating state, a part of the adjusting part undergoes reverse transformation to return to the A phase. (D) As a result, the local portion heated above the point Af returns to the original first shape. Then, when the local heating (for example, by laser irradiation) is interrupted and the temperature of the entire adjusting portion including the locally heated portion becomes equal to or lower than the Ms point, the entire adjusting portion becomes the M phase again. At this time, new stress is generated at the boundary between the portion where the shape is locally recovered and the portion where the shape is plastically deformed. Due to this internal residual stress, the adjustment portion is slightly displaced by δ with respect to the plastically deformed shape (second shape).

By confirming this basic principle, the inventors immediately obtained the following concept of the posture adjusting mechanism. That is, the ability to control the volume of the locally heated portion (volume of the shape-recovered portion) with respect to the entire material means that the entire material is plastically deformed (second shape) and memorized initially. That is, it is possible to intentionally create a shape between the shapes (first shape). That is, if the functional component is fixed to the shape memory material with resin at the shape recovery temperature or lower in advance, the attitude of the objective lens can be adjusted to a desired state based on this basic concept.

In particular, according to the present invention, since the posture can be adjusted by heating at most a hundred and several tens of degrees, even if a laser is used, the posture can be adjusted with a small power, and the adjusting device can be simplified, and a saving can be achieved. It has excellent characteristics in terms of practical use and production technology in terms of power conversion and safety improvement.

Therefore, according to the present invention, the adjustment time can be shortened, the adjustment device can be simplified, the power saving and the safety can be improved as compared with the conventional example, and the production technology can be practically compared with the conventional example. Is winning.

As described above, the most remarkable point of the present invention is that the submicron order posture control is possible because the minute displacement based on the local phase change of the supporting member is utilized. Further, once the posture is fixed, the posture can be stably maintained with almost no change with time such as relaxation of strain due to aging.

In the case of fixing the objective lens by the conventional resin, the posture shift due to the curing and shrinkage of the resin has been a problem, but in the case of the position adjustment utilizing the shape memory effect of the present invention, this kind of problem occurs. Can be completely avoided.

As long as it is based on the basic principle of the present invention, coarse adjustment and fine adjustment of the objective lens can be performed by controlling the ratio of the portion that has undergone reverse transformation to the portion that is plastically deforming. In particular, as in the invention described in claim 4,
When a laser is used as the means for locally heating, the position of the objective lens can be adjusted more easily by controlling the laser irradiation area.

[0032]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an objective lens driving device used in an embodiment of the objective lens position adjusting method of the present invention. The objective lens driving device includes an objective lens 6 and an objective lens holder 6 a that holds the objective lens 6. The objective lens holder 6a is supported by a parallel leaf spring 13 for focus movement. The parallel plate spring 13 bends the objective lens 6 so that the objective lens 6 can swing in the direction of the arrow F, which is the optical axis direction of the objective lens 6. The focus movable parallel leaf spring 13 is connected to an intermediate support 14, and one end of the intermediate support 14 is supported by a radial movable leaf spring 16 fixed to a columnar projection 15 a of a base 15. As a result, the intermediate support 14 and the objective lens holder 6a can swing in the arrow R direction, which is the radial direction.

Further, the focus drive coil 17 and the radial drive coil 18 wound around the objective lens holder 6a.
Crosses the magnetic flux generated in the gap 19a of the magnetic circuit 19. Therefore, when the coils 17 and 18 are energized, a force is generated in the arrow F direction and the arrow R direction, and the objective lens holder 6 is moved in the arrow F direction and the arrow R direction.
It is possible to move a and the objective lens 6.

The objective lens 6 is used as an embodiment of the method for adjusting the position of the objective lens of the present invention in the above-mentioned objective lens driving device.
The supporting method and the position adjusting method will be described in more detail below.

FIG. 2 is a three-sided view showing only the objective lens 6 and the objective lens holder 6a shown in FIG. 1, FIG. 2 (A) is a plan view, and FIG. 2 (B) is a side view. FIG. 2 and FIG.
2C is a sectional view taken along line XX in FIG.

As shown in FIG. 2A, the objective lens supporting members 21a, 21b and 21c are composed of base portions 21a-2 and 21b.
-2 and 21c-2, and tip portions 21a-1, 21b-1 and 21c bent from the base portions 21a-2, b-2, c-2.
-1. The tip portions 21a-1 and 21b-1
And 21c-1 are brought into contact with the lower surface of the circumferential flange portion 6b of the objective lens 6. Further, the support members 21a, 21b and 21c have the base portions 21a-2 and 21b-.
2 and 21c-2 are fixed to the objective lens holder 6a.

The objective lens supporting members 21a, 21b and 2
1c is composed of, for example, a shape memory alloy represented by a Ni-Ti alloy or a Cu-Zn-Al alloy. The Af point of this shape memory alloy changes due to a slight difference in the composition ratio of the shape memory alloy material, and in the case of the Ni-Ti alloy, it is Ni.
Content of 53 to 56 (wt.%), Af point is 30 to 10
Changes to around 0 ° C. The temperature difference between Ms point and Af point is a few
It is several tens of degrees Celsius. The Af point of the shape memory alloy used for the supporting members 21a, 21b, 21c was adjusted to 80 ° C or more in consideration of the operating temperature environment of the consumer equipment and the heat generated from the equipment, and the composition ratio of the shape memory alloy was adjusted. .

According to the method of adjusting the position of the objective lens of this embodiment, first, as shown in FIG.
A, 21b, 21c is bent and deformed in the Z-axis direction (direction in which the reference plane 24 is facing) with the heating parts 22a, 22b, 22c as the central axes of bending, and in that state 400 to 900 ° C, preferably 500 to Heat treatment is performed at 600 ° C. for about 1 hour to memorize the bent shape. The reference plane 24
Is a reference plane for fixing the objective lens 6 to the objective lens holder 6a.

Next, as shown in FIG. 2 (E), the deformed portions of the supporting members 21a to 21c (that is, the distal end portions 21a-1 and 21a-2 and 21a-3) in which the above-mentioned bent shapes are memorized are heated. 22a to 22c are central axes, and the heating portions 22a to 22c are flattened with respect to the reference surface 24 by plastically deforming in a direction opposite to the method in which the reference surface 24 is oriented along the Z axis below the Ms point. . And, the base portions 21a-2, 21 of the support members 21a to 21c
b-2 and 21c-3 are bonded to the objective lens holder 6a at room temperature. Then, the objective lens 6 is attached to the tip portions 21a-1, 21b-1, 21c-1 of the supporting members 21a to 21c by the adhesives Wa, Wb, Wc.
Are attached to obtain an objective lens assembly as shown in FIGS. 2 (A), (B) and (C). Alternatively, the objective lens 6 and the support member 22
After adhering a to c, it is mounted on the objective lens holder 6a. At the time of this mounting, it is necessary that the support members 22a to 22c made of a shape memory alloy do not undergo transformation by heating and do not return from the plastically deformed shape to the memorized shape. In the case of the thermosetting adhesive, It is preferable that the curing temperature is sufficiently lower than the transformation point of the alloy, and further, it is preferable to use an ultraviolet curing type / anaerobic adhesive which does not require heating during curing.

In FIG. 2A, for the sake of simplification, the objective lens 6 is drawn by supporting members 21a to 21c having the same shape so as to be supported at every approximately 120 ° in the circumferential direction. It suffices not to lose the balance with respect to the servo operation in the radial direction. For example, if the balance is unbalanced only by the support member, a dummy material as a balancer may be attached to the objective lens holder 6a.

The objective lens assembly composed of the objective lens 6, the objective lens holder 6a and the supporting members 21a to 21c is fixed to the main body of the apparatus constituting the objective lens driving device shown in FIG. Flange portion 6b of objective lens 6
Are supported by objective lens support members 21a, 21b, 21c fixed to the objective lens holder 6a.

Objective lens support members 21a, 21b, 21c
In addition, the heat energy is independently applied to each of the tip end portions 21a-1 and 21a-1 by adjusting the area (which can also be expressed as a volume in consideration of the depth direction) for shape recovery.
The amount of displacement of 1b-1 and 21c-1 in the Z-axis direction can be adjusted.

FIG. 3 shows the local heating of the support members 21a to 21c by the laser beams 100a to 100c. By adjusting the irradiation energy and irradiation area of the laser beams 100a to 100c, the tilt angle θ and the height (position in the direction of the optical axis 7a) of the objective lens 6 can be adjusted.

Laser beams 100a, 100b, 100c
Is oscillated by a laser oscillator (not shown) and is supported by a focusing lens (not shown) by the supporting members 21a, 21b, 21.
It is placed either on focus on c or intentionally off focus for effective local heating. The laser beam 100 may be any one as long as it can heat a part of the heating portions 22a, 22b, 22c of the supporting members 21a, 21b, 21c to the point Af or higher, but it is preferable to use a YAG laser whose power can be controlled by the pulse width. .

When the laser beam 100 is applied to the heating portion 22 of the supporting member 21, the power of the laser beam 100 is fixed and the laser irradiation area is changed to adjust the height of the objective lens 6 roughly and finely. It can be performed with submicron accuracy. Further, the laser beam 100
If the laser irradiation area is fixed and the irradiation time is controlled, the depth of the transformed portion of the heating portion 22 in the thickness direction can be controlled, and rough adjustment and fine adjustment of the height of the objective lens 6 can be performed with submicron accuracy. You can Further, by combining the control of the irradiation area of the laser beam 100 and the control of the irradiation time, rough adjustment and fine adjustment of the height of the objective lens 6 can be performed with submicron accuracy.

Specifically, for example, the laser beam 100
When the spot diameter is 100 μm and the irradiation power is 100 mw, and the irradiation for 100 ms is performed only once in the substantially central portion surrounded by the broken lines of the heating portions 22a, 22b and 22c shown in FIG. It was possible to displace 6 in the F direction (height direction) by 1 μm. The irradiation energy density of the laser beam 100 at this time is 1.3 × 10 ³ w / cm ² and the input energy is 10 mJ.

More specifically, as shown in FIG. 3 (A), when the optical axis of the objective lens 6 is inclined by an angle θ with respect to the optical axis 7a, as shown in FIG. 3 (B), The heating portions 22a, 22b and 22 of the objective lens supporting members 21a, 21b and 21c
Laser beam 100a, 100b, and 100c is irradiated to c. By this irradiation, the inclination of the objective lens 6 with respect to the optical axis 7a is adjusted, and the laser beam 100a is adjusted so that the optical axis of the objective lens 6 and the optical axis 7a from the light source coincide with each other, as shown in FIG. The irradiation area, irradiation time and irradiation frequency of 100b and 100c may be set.

The tilted amount of the objective lens 6 can be measured by observing the shape of the beam emitted from the objective lens 6. The tilt amount can also be measured by observing the angle formed by the assembly reference plane (not shown) and the flange portion 6b of the objective lens 6 with a predetermined observing device.

In this embodiment, in order to displace the tips 21a-1 to 21c-1 of the support members 21a to 21c, the phase change of the shape memory material constituting the tips is applied. Therefore, according to this embodiment, the adjusted position (posture) of the objective lens 6 can be permanently fixed. Therefore, since it is not necessary to bond and fix the objective lens 6 to the objective lens holder 6a, the bonding and fixing step which is conventionally required can be omitted.

Next, as shown in FIG. 4 (A), when there is an assembly error Δ in the focus direction (height direction) of the actuator or the pickup to which the objective lens holder 6a is fixed, there is a case shown in FIG. 4 (B). ), The objective lens support member 2
Laser beams 100a, 100 for 1a, 21b, 21c
Irradiate b and 100c. Then, by controlling the irradiation area, the irradiation time, and the number of times of this irradiation, the displacement amount of the tip portions 21a-1 to 21c-3 of the supporting members 21a to 21c-3 is controlled, and the height direction of the objective lens 6 is controlled. Displacement is controlled, and Fig. 4
As shown in (C), the assembling error Δ in the height direction can be eliminated.

By the way, a mirror (not shown) is provided at the turntable reference height 30 shown in FIG. 4A, and the objective lens height is adjusted so that the mirror is located at the focal point 31 of the objective lens 6. For example, a resonator is formed by the mirror and the cleavage plane of the semiconductor laser light source (not shown) inside the pickup, and the output of the semiconductor laser light source increases. Therefore, if this output is monitored by the stray light detector (not shown) inside the pickup and the increase in the output is detected, it can be seen that the height adjustment of the objective lens 6 is completed.

The tilt adjustment work and the height adjustment work of the objective lens 6 described with reference to FIGS. 3 and 4 can be simultaneously performed by controlling the irradiation spot, the irradiation area, and the irradiation time of the laser beam. it can.

As described above, according to this embodiment, the optical axis of the objective lens 6 can be adjusted without using spacers or screws. Therefore, the time and labor for adjusting the position of the objective lens 6 can be reduced, and the adjusting device can be made compact. Moreover, in this embodiment, since the minute displacement based on the local phase change of the support member 21 is utilized, the position can be precisely adjusted in the submicron order. Further, since the supporting member 21 supports three positions in the circumferential direction of the objective lens 6, not only the inclination of the optical axis of the objective lens 6 but also the position (height) of the objective lens 6 in the optical axis direction.
Can also be adjusted. Therefore, the efficiency and automation of the adjustment work can be significantly increased. Further, since the tilt adjusting mechanism and the height adjusting mechanism can be used as the adjusting device, a mechanism for adjusting the height is not separately required, and the driving device for driving the objective lens 6 can be designed in a small size. Therefore, it is advantageous for thinning and downsizing the pickup and the optical disc device including the above drive device. Further, according to this embodiment, the support member 21 is made of a shape memory alloy. Since the Af point of the shape memory alloy is 80 ° C. or higher, the time required for heat dissipation can be reduced. Therefore, the time required for position adjustment can be shortened and the production efficiency can be improved. Further, according to this embodiment, since the support member 21 is locally restored in shape by using the laser, the support member 21
The support member 21 can be displaced without mechanical contact with the. Therefore, the position of the objective lens 6 can be adjusted particularly precisely. Further, according to this embodiment, the posture and position can be adjusted after the curing shrinkage caused by the adhesive, which is convenient. Further, according to this embodiment, since the posture / position adjusting mechanism can be simplified, the weight can be reduced. Therefore, a margin can be obtained in the servo system design in the focus / radial direction of the objective lens, which is also effective in reducing the overall size and weight.

In the above embodiment, the support member 21 is
A laser beam was used as the heating means for heating the local portions (heating portions 22a to 22c) of a to c. However, instead of the laser beam, a heating tool such as a thermal head is used, and this heating tool is used for the supporting member 21a. Alternatively, the inclination and height position of the objective lens 6 may be adjusted by bringing them into contact with ~ c.

Any method of heating the supporting members 21a, 21b, 21c may be used as long as it is a local heating method such as a laser, a heater, an electron beam or the like, but the laser can easily adjust the temperature, the irradiation area, the irradiation time and the like. Therefore, in this embodiment, the heating method by the laser is described.

[0057]

As is apparent from the above description, in the objective lens position adjusting method according to the first aspect of the present invention, the support member is locally heated to a temperature higher than the shape recovery temperature to recover the shape. The optical axis of the objective lens can be adjusted with respect to the optical axis of. Therefore, according to the invention of claim 1, the optical axis of the objective lens can be adjusted without using a spacer or a screw. Therefore, the time and labor for adjusting the position of the objective lens can be reduced, and the adjusting device can be made compact. Moreover, according to the present invention, since the minute displacement based on the local phase change of the supporting member is utilized, it is possible to perform the precise position adjustment on the order of submicron.

Further, according to the invention of claim 2, since the supporting member supports three or more positions in the circumferential direction of the objective lens, not only the inclination of the optical axis of the objective lens but also the light of the objective lens The axial position (height) can also be adjusted. Therefore, the efficiency and automation of the adjustment work can be significantly improved as compared with the adjustment work only for adjusting the inclination. Further, since the tilt adjusting mechanism and the height adjusting mechanism can be used as the adjusting device, a mechanism for adjusting the height is not separately required, and in addition to the effect that the actuator for driving the objective lens can be designed in a small size, This is advantageous in reducing the thickness and size of the pickup and the optical disc device including the actuator.

According to the invention of claim 3, the supporting member is made of a shape memory alloy. Since the Af point of the shape memory alloy can be set to 80 ° C. or higher, the time required for heat dissipation can be reduced. Therefore, the time required for position adjustment can be shortened and the production efficiency can be improved.

Further, according to the invention of claim 4, since the shape of the supporting member is locally recovered by using the laser, the supporting member can be displaced without mechanical contact with the supporting member. Therefore, the objective lens can be adjusted particularly precisely.

Further, according to the present invention, the posture and position can be adjusted after the curing shrinkage caused by the adhesive, which is convenient. Further, according to the present invention, the posture / position adjusting mechanism is simplified, so that the weight can be reduced. Therefore, a margin can be obtained in the servo system design in the focus / radial direction of the objective lens, which is also effective in reducing the overall size and weight.

[Brief description of drawings]

FIG. 1 is a perspective view of an objective lens driving device to which an embodiment of an objective lens position adjusting method according to the present invention is applied.

FIG. 2A is a plan view of an objective lens assembly having an objective lens holder 6a and a supporting member to which the above embodiment is applied, and FIG. 2B is a side view of the assembly. ,
2C is a sectional view taken along line XX in FIG.
FIG. 2D is a perspective view showing a memory shape of the support member, and FIG.
(E) is a perspective view showing a plastically deformed shape of the support member.

FIG. 3A is a diagram showing a state in which the optical axis of the objective lens is tilted with respect to the optical axis of the light source in the above-described embodiment, and FIG. FIG. 3C is a diagram showing a state where the optical axis of the objective lens is aligned with the optical axis of the light source.

FIG. 4 (A) is a diagram showing a state in which the height of the objective lens is lower than the predetermined position by Δ in the above-described embodiment, and FIG. FIG. 4 (C) is a diagram showing a state in which the height position of the objective lens is at a predetermined position.

FIG. 5 is a diagram showing a first conventional example.

FIG. 6 is a diagram showing a second conventional example.

FIG. 7 is a schematic view of a minute displacement mechanism utilizing local shape recovery for explaining the principle of the present invention.

[Explanation of symbols]

6 ... Objective lens, 7a ... Optical axis, 13 ... Focus movable leaf spring, 16 ... Radial movable leaf spring, 17 ... Focus drive coil, 18 ... Radial drive coil, 19 ...
Magnetic circuit, 21a-c ... Objective lens support member, 22a-c
... Heated portion of support member, 24 ... Reference plane, 30 ... Turntable reference height, 31 ... Objective lens focus, 100a-c
... heating laser beam, 51 magnetic disk, 52 spindle motor, 53a laser source, 54 objective lens drive device.

Front page continued (72) Inventor Toshiyuki Tanaka 22-22 Nagaikecho, Naganocho, Abeno-ku, Osaka-shi, SHARP Co., Ltd. Within

Claims (4)

[Claims] 1. A support member made of a material having a shape memory effect is provided between an objective lens and an objective lens holder for holding the objective lens, and the support member serves to support the objective lens holder. The objective lens is supported, and the support member is partially heated to a shape recovery temperature or higher,
By locally recovering the shape, internal stress is generated in the support member, and the support member is deformed to adjust the optical axis of the objective lens with respect to the optical axis from the light source. Adjusting the position of the objective lens. 2. The method for adjusting the position of an objective lens according to claim 1, wherein the support member supports three or more positions in a circumferential direction of the objective lens, and the support member locally recovers its shape. ,
A method of adjusting a position of an objective lens, comprising adjusting an inclination angle of an optical axis of the objective lens with respect to an optical axis from the light source and a position of the objective lens in an optical axis direction. 3. The position adjusting method for an objective lens according to claim 1, wherein the supporting member is made of a shape memory alloy. 4. The method for adjusting the position of an objective lens according to claim 1, wherein the support member made of a material having a shape memory effect is locally irradiated with a laser, A method of adjusting the position of an objective lens, which comprises locally recovering the shape of a support member and adjusting the optical axis of the objective lens with respect to the optical axis from a light source.