JPH0381208B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a leaf spring for an optical element drive device suitable for application to a pickup device of an optical disc playback device.

For example, when reproducing a disc on which audio PCM signals have been recorded with or without pits, it is necessary for the laser beam for reading to focus correctly on the signal recording surface of the disc, so that the objective lens of the optical pickup device and the signal Focus servo is performed so that the distance to the recording surface is always constant.

FIG. 1 shows a structure for supporting an objective lens of a conventional optical disc playback device. In the figure, 1 is an objective lens, 2 is a cylindrical lens holder, 3 is a base body, and 4a and 4b are lenses. These are two leaf springs whose both ends are fixed to the holder 2 and the base 3, respectively. A coil 6 is wound around a winding frame 5 fixed to the lens holder 2. In addition, 7 is the lens holder 2
The cup-shaped yoke has a central ball with a central hole through which a magnet is inserted, and a ring-shaped magnet 8 is provided on the periphery of the cup-shaped yoke. The yoke 7 and the magnet 8 are provided and fixed on a mounting plate 9 screwed to the base body 3.

The laser beam is incident from the lower side of the lens holder 2 through the objective lens 1 onto the signal recording surface of the upper disk (not shown), and on the other hand, the laser beam is guided downward through the objective lens 1 along the same path. The incident light is separated from the incident light by a beam splitter (not shown) and is made to enter the light receiving element. By supplying this reflected light to a cylindrical lens, the amount and direction of the focus shift are detected, and a focus error signal is supplied to the above-mentioned coil 6, so that the objective lens 1 and the lens The holder 2 is integrally displaced in the vertical direction.

When such a focus servo operates,
The leaf springs 4a, 4b have the function of creating a neutral point during displacement operation;
There is a primary resonance frequency ₀ unique to b. Now the first
Setting up the equation of motion for the configuration shown in the figure, G(s) = Output displacement X/Input voltage V = K/(ms ² +k
)(Ls+R) However, G(s): transfer function, X: displacement of objective lens 1, m: weight of moving part, k: spring constant, V: input voltage, L: inductance of coil 6, R:
Low resistance of coil 6, K: Electromagnetic force generating part (coil 6,
This is the current sensitivity of the yoke 7 and magnet 8).

From the above formula, the resonance frequency ₀ is determined by m and k, and Q in the secondary system is generally 10 to 205
[dB/oct] For example, it is 20 [dB/oct], which is quite large and has a negative effect on the stability system of focus servo operation. FIG. 2A shows the frequency characteristics of the displacement of the spring system in the conventional support device.

In order to damp the Q of the resonance of the leaf springs 4a, 4b, as shown in FIGS.
It is proposed to paste b. However, in this configuration, as the leaf springs 4a, 4b deform, the rubbers 10a, 10b also deform, so as shown in FIG. 2B, although the Q decreases to about 15 [dB/oct], , it is not possible to obtain a sufficient dumping effect.

Therefore, the present applicant has previously proposed an optical system support device that provides a sufficient damping effect. This will be explained below with reference to FIG. In addition, in FIG. 4A, illustration of the electromagnetic force generating section for displacing the lens holder 2 shown in FIG. 1 is omitted. Leaf springs 4a, 4b
Polymer compounds 11a and 11b having damping properties are deposited so as to cover one side of each of the substrates, and vibration damping members each having an L-shaped cross section are attached to the corner portions where the polymer compounds 11a and 11b contact the base 3. 12
a, 12b are provided to constitute two leaf springs 4A, 4B for supporting the lens holder 2 with respect to the base body 3. In this case, the lower surfaces of the damping members 12a, 12b and the upper surfaces of the polymer compounds 11a, 11b are fixed, and the back surfaces of the damping members 12a, 12b and the base 3
is fixed.

The leaf springs 4a, 4b are made of stainless steel or amorphous metal and have a thickness of 50 μm, and the damping members 12a, 12b are made of the same material and thickness as the leaf springs 4a, 4b. It is something. Moreover, as the polymer compounds 11a and 11b, 0.6 [mm] to 0.9
Butyl rubber or silicone rubber with a thickness of [mm] can be used. In addition to this, an adhesive having damping properties may be applied. Examples of materials that have such adhesive properties include acrylic alkyl ester flexible resins. Since the parts of the polymer compounds 11a and 11b located below the damping members 12a and 12b are prevented from moving together with the leaf springs 4a and 4b, the internal loss is lower than in other parts. Becomes large.
In other words, the vibrations of the leaf springs 4a, 4b cause internal friction in the polymer compounds 11a, 11b, which generates thermal energy and absorbs the vibrations. Therefore, as is clear from the frequency characteristics in Fig. 5, the Q of the secondary spring system is, for example, 6.
It can be reduced to about [dB], and a sufficient vibration isolation effect can be obtained.

6 to 8 respectively show modifications of FIG. 4, and in the case of FIG. 6, secondary leaf springs 4a, 4
Polymer compounds 11a and 1 are placed on the opposing plate surfaces of b, respectively.
1b, and these polymer compounds 11a, 11b
A damping member 12a is provided at the corner portion where is in contact with the base body 3,
12b is provided. In addition, in the case shown in FIG. 7, the damping members 12a and 12b are made of polymer compound 1
a and 11b are provided at the corner portions in contact with the lens holder 2. In short, the vibration damping member 12
a and 12b are provided so as to suppress movement of the polymer compounds 11a and 11b following the vibrations of the leaf springs 4a and 4b. However, as in the configuration shown in FIG. 4 or FIG.
By providing , the damping effect becomes slightly better,
Also, the compliance of the moving parts does not decrease.

Furthermore, it is also possible to provide the damping members 12a and 12b at both the corner portion on the side that contacts the lens holder 2 and the corner portion on the side that contacts the base 3.

Furthermore, as shown in FIG.
A tape or sheet-like polymer compound 11a (or 11b) between a, 4a' (or 4b, 4b')
One end of each of the leaf springs 4A and 4B, which have a three-layer structure with a
It may be fixed to. In the configuration shown in FIG. 8, since the vibration modes of each of the two leaf springs 4a, 4ba'; 4b, 4b' of the two laminated leaf springs 4A, 4B do not completely match, one serves as a damping plate for the other, so there is no need to provide a damping member having an L-shaped cross section as described above.

The leaf springs 4A and 4B shown in FIG. 8 have a substantially isosceles triangular shape as shown in FIG. 9, and holes 15, 16, and 17 are formed at the top of each of the leaf springs 4A and 4B. Leaf spring 4
The hole 15 portions of A and 4B are the retaining rings 2a and 2b.
It is also bonded to both ends of the lens holder 2. or,
The holes 16 and 17 of the leaf springs 4A and 4B are connected to the base 3.
With washers 3a and 3b, screws 3c,
Stop by 3d.

The shapes of the leaf springs 4A, 4B and how to attach them to the lens holder 2 and base 3 are shown in FIGS. 4 and 6.
It can also be applied to the optical system support device shown in FIG. 7 and FIG.

Note that when using polymer compounds (for example, acrylic, alkyl, ester flexible resins) 11a and 11b that have not only damping properties but also adhesive properties, it is necessary to This has the advantage that the problem that the spring constant substantially increases due to curing of the adhesive does not occur.

Therefore, the optical system support devices shown in FIGS. 4, 6, 7, and 8 have a plate spring coated with a polymer compound having damping properties, and a vibration damping member provided thereon. Since the leaf spring is constructed using a simple structure, the Q of the spring system that supports the optical system can be sufficiently damped, and if these are applied to the objective lens support device in an optical disc playback device,
It is possible to prevent the focus servo operation from becoming unstable.

Note that, for tracking correction, a leaf spring is used when the optical axis of the objective lens can be displaced in a direction perpendicular to the signal track of the disk.
Alternatively, the optical system support device described above may be applied to a leaf spring used when the optical axis of the objective lens can be displaced in the direction of extension of the signal track for time axis correction. Further, the above-described optical system support device can be applied not only to an objective lens but also to support devices such as a beam splitter and a mirror.

By the way, in order to manufacture the leaf springs 4A, 4B of the optical system support device explained with reference to FIGS. 8 and 9, for example, a thin metal substrate is etched to form the leaf springs 4a, 4b; 4a', 4b' into desired shapes. A polymer compound containing a solvent is applied to each surface of the leaf springs 4a and 4b, and then the holes 15 and 15 of the leaf springs 4a and 4b are formed.
The polymer compounds 16 and 17 are coated with a solvent, and then each of the polymer compounds 11a and 11b is coated with a solvent.
Other leaf springs 4a' and 4b' were pasted on top of these, respectively.

For this reason, the conventional manufacturing method for leaf springs is extremely troublesome and has the disadvantage of leading to an increase in price.

In view of this point, the present invention proposes a manufacturing method that can easily manufacture a leaf spring for an optical system support device.

Hereinafter, one embodiment of the present invention will be described in detail with reference to FIGS. 10 to 12. In this embodiment, the leaf spring described with reference to FIGS. 8 and 9 above is obtained.

As shown in FIG. 10, thin metal base materials (for example, 10 to 50 μm thick) M and M' are used as spring base materials, and double-sided adhesive tape (for example, 50 to 100 μm thick) is used as a thin polymer compound base material having damping properties. )S
are prepared, and as shown in FIG. 11, metal base materials M,
The three are laminated and combined so that the tape S is sandwiched at M'. In this case, instead of the tape S, a polymer compound containing a solvent is applied to one side of the metal base materials M, M' to form a layer S, and on this layer S, the metal base materials M, M' are coated. You may also be able to attach the other one. still,
The metal substrates M and M' are the same or different metals.

Next, the laminated and combined three pieces are punched out as shown in FIG. 11 to obtain leaf springs 4A and 4B of desired shapes as shown in FIG. 12.

According to the present invention described above, in a method for manufacturing a plate spring for an optical element driving device in which an optical element is attached to a base by a plate spring, a polymer compound group having damping properties is formed on a first spring base material. After the second spring base material was laminated so as to sandwich the polymer compound base material with the first spring base material, the leaf spring was obtained by punching out the desired shape. Since the vibration modes of the first and second leaf springs do not match, one of them serves as a restraining plate for the other, making it possible to easily and reliably use the leaf spring of an optical element drive device that provides a good damping effect. can be made to

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a conventional optical system support device, Fig. 2 A and B are characteristic curve diagrams, and Fig. 3 A and B
4A and 4B are a cross-sectional view and a perspective view showing a part of another example of a conventional optical system support device, and FIGS. 4A and 4B are an example of an optical system support device to which the plate spring obtained by the manufacturing method of the present invention can be applied. 5 is a characteristic curve diagram, and FIGS. 6, 7, and 8 are optical system support devices to which the leaf spring obtained by the manufacturing method of the present invention can be applied. FIG. 9 is a plan view showing the leaf spring of the device shown in FIG. FIG. 1 is an objective lens, 2 is a lens holder, 4a, 4
a'; 4b, 4b'; 4A, 4B are leaf springs, 11a,
11b is a polymer compound, 12a and 12b are vibration damping members, M and M' are spring base materials, and S is a polymer compound base material.

Claims (1)

[Claims] 1. In a method for manufacturing a leaf spring for an optical element driving device in which an optical element is attached to a base by a leaf spring, a polymer compound base material having damping properties is deposited on a first spring base material, and An optical element characterized in that a second spring base material is laminated so as to sandwich the polymer compound base material together with the first spring base material, and then punched into a desired shape to obtain the leaf spring. Manufacturing method for leaf springs for drive devices.