JPS62246152A - Optical pickup driving device - Google Patents

Abstract

PURPOSE:To make a driving device smaller-sized and thinner than a conventional electromagnetic driving device by using piezoelectric elements or electrostrictive elements to constitute the driving device of an optical pickup. CONSTITUTION:Piezoelectric elements 13, 15, and 16 are connected through a revolving shaft 19 and a fulcrum 18 by a connecting rod 17, and an optical pickup 12 is connected to the piezoelectric element 13 by an elastic body 14. A guide 10 is provided for the purpose of suppressing oscillation of the connecting rod 17. A voltage applied to the piezoelectric element 15 is changed to move the optical pickup 12 near a desired information track. The piezoelectric element 16 is provided in a position of low displacement expansion rate in the middle of a displacement expanding mechanism, and the optical pickup 12 is displaced across information tracks in the direction of an arrow F by th error signal from the optical pickup 12 to match the light spot of the optical pickup 12 to a desired information track. Meanwhile, the optical pickup 12 is displaced in the direction where the light spot is approximated to and separated from a recording medium 11, namely, the focus direction by the piezoelectric element 13.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to the structure of a drive device for driving an original pickup.

[Conventional technology]

As shown in FIG. 5, a conventional optical pickup driving device includes air circuits 351, 352, 35.5 and coils 361.
It was a Tatsuta type drive device consisting of 362 and 363. The driving device composed of 351 and 361 drives the entire stroke in the information track transverse direction G, and the @ moving device composed of 352 and 362 drives only the objective lens 31 in the entire track transverse direction G. The driving device 353 and 363 drives the objective lens 31 in the direction H toward and away from the recording medium 11. These drives bring the light 34 of the optical pickup to the desired information track and are moved by small movements by error signals from the optical pickup.
The function of accurately converging the light 54 from the light source 33 onto the signal position of the recording medium 11 is 1! have money

[The problem that the invention attempts to solve]

However, the above-mentioned Kyuden Yu type optical pickup drive device,
It is heavy and large, and consists of a circuit 351°352.353 containing a magnet and a coil that drives a heavy pickup including a lens system, and a coil 361°562.565 that passes a driving current. This is a hindrance to miniaturization of light vehicles.

In recent years, optical recording devices, such as double-type compact disc players, have become smaller and thinner. Mano, optical pickup is also a journal of the Institute of Electronics and Communication Engineers' 85/10
vol, J68-a 1099803-811
A structure in which thin-film optical elements are integrated has also been proposed, as described in 2013.In this case, the weight of the pickup is lighter than that of conventional optical pickups, so the generated force required for the drive device that drives the optical pickup is also reduced. It is smaller than the conventional drive system.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an optical pickup tailing device that is small and compact.

[Means to solve the problem]

(1) The optical pickup driving device of the present invention is a driving device for driving an optical pickup used in a device that writes and reads information by optical means, in which the displacement of the optical pickup is controlled by a piezoelectric element or an electric device. It is characterized in that it is caused by displacement occurring in a strain element (hereinafter collectively referred to as a piezoelectric element).

(2) Ninth, the transmission means for transmitting the displacement generated in the piezoelectric element to the optical pickup is provided with a mechanism for magnifying the displacement.

(3) A second feature is that the displacement of the optical pickup in the direction across the information track of the recording medium is caused by at least one piezoelectric element.

(4) In addition, the optical pickup 'fI--displacement in the direction of approaching and separating from the recording medium surface can be controlled by laminating at least one piezoelectric material or electrostrictive material (hereinafter collectively referred to as piezoelectric material) over a length of It is characterized in that it is generated by combining at least two or more piezoelectric elements of the same or different sizes and adjusting the voltage applied to each piezoelectric element.

(5) In addition, optical fiber optics can mix, form, or monolithically incorporate thin-film optical elements such as light-emitting elements, light-receiving elements, waveguide lenses, and waveguide beam splitters into one optical pickup. It is characterized by

[Effect]

According to the above configuration of the present invention, the displacement caused by laminating thin piezoelectric bodies and applying voltage to the piezoelectric element is magnified by the fc displacement magnification mechanism by applying the lever principle, and all information tracks on the recording medium are expanded. Obtain the amount of movement of the optical pickup that allows access. Well, in addition to this piezoelectric element, we also provide a piezoelectric element that slightly displaces the optical pickup in the cross-track direction, and a piezoelectric element that slightly displaces the optical pickup in the direction of moving toward and away from the recording medium surface. To precisely control the position of a spot at a signal position on a recording medium.

[Example 1] FIG. 1 is a diagram showing a first embodiment of the present invention.

Reference numeral 11 denotes an optical disc recording medium, which performs a circumferential movement.

First, the configuration of the optical pickup driving device will be explained. 12
is a 4i''/area ratio optical pickup as shown in FIG. A buffer chip 42 and a quartz-based optical waveguide 1jl 45 are laminated on a substrate 41 such as 81. A semiconductor laser 121 is end face coupled to one end of the optical waveguide film 43. The light 47 incident on the film 43 passes through the waveguide beam splitter 44 and enters the condensing waveguide lens 12.
2, the light is radiated into space and condensed at a point 46 in space.

When the signal position on the optical recording medium is brought to this spot position and the reflected light is returned to the condensing waveguide lens 122,
The signal light enters the optical waveguide film 43, is divided by the waveguide beam splitter 44, and detected by the photodiode array 45, so that a signal output, a tracking error signal, and a focusing error signal can be detected.

The piezoelectric elements 13, 15, and 16 are connected by a connecting rod 17 via a rotating shaft 19 and a fulcrum 18, respectively, and the optical pickup 12 is connected to the piezoelectric element 13 by an elastic body 14. A guide 10 is also provided to suppress vibration of the connecting rod 17.

The structure of piezoelectric elements 15 and 16 is shown in FIG. Piezoelectric material P
b (Zr, 1) 03 series and electrostrictive materials pb (Mg, Nb
5A) OB-based thin plates 51 are stacked with electrodes 52 in between and polarization 53 in opposite directions, and when a potential 54 is applied alternately to each electrode, the piezoelectric element expands and contracts in the thickness direction (
In the direction of the arrow 51), with about 200 double compensation layers, the length L of the piezoelectric element is 60 m, and when 100 V is applied, a displacement of about 50 μm at 9 o'clock can be obtained. The cross-sectional area of the piezoelectric element 15 is 4 #
It is X4 Shizuku. In this example, the pressure is 1! Element 15
If the displacement flh is 50 μm, the displacement flrB will also be approximately 50 μm, and the lever made up of the fulcrum 18 and the connecting rod 17 will cause the displacement j1-0 to be approximately Q, 45III11, and similarly, the displacement 1・D will be approximately 551111, and the pickup The displacement tl of 12 is expanded to about 50.6. Therefore, by changing the voltage applied to the piezoelectric element 15, the optical pickup 12 can be moved to the vicinity of a desired information track.

A piezoelectric element 16 is also provided in the middle part of the displacement magnifying mechanism.

Since the displacement caused to the optical pickup by the piezoelectric element 15 is magnified by the displacement magnification mechanism, it is difficult to displace the optical pickup 12 accurately enough to distinguish the pitch of 1.6 μm between the information tracks on the recording medium.
A piezoelectric element 16 is also provided in the displacement magnification mechanism (indicated by ■) at a location where the displacement magnification rate is small, and the optical pickup 12 is displaced in the direction across the information track by the error signal from the optical pickup 12. Align the light spot with the given information track.

- 10,000, optical pickup 1 in a direction that brings the optical spot close to and away from the recording medium 11, the so-called focus direction
The displacement of 2 is created by the piezoelectric element 13. This piezoelectric element 1
The 'Ifi-tree-like method of creating displacement using 5 will be explained with reference to FIG. Two sheets of piezoelectric material or electrostrictive material 61 are laminated with electrodes 62f with polarization directions 64 opposite to each other and bonded together to form a pneumatic piezoelectric element.

When the piezoelectric element is fixed at a voltage 63 and a voltage 65 is applied, a displacement occurs at the tip of the piezoelectric element. In this example, the thickness t is (135 μm, the length l is 30 mm, and the voltage is 4
At 0V, the displacement is approximately 0.4 degrees. but,
When the optical pickup 12fr is attached to the tip of this piezoelectric element and displaced, the angle formed between the optical pickup 12 and the recording medium 11 also changes, and the signal light from the recording medium 11 no longer returns to the optical pickup 12, resulting in displacement in the focus direction. A mechanism is required that not only causes this, but also maintains a constant angle between the optical pickup 12 and the recording medium 11. This mechanism will be explained in a few sentences.

Two sets of piezoelectric elements as shown in FIG. 6 are attached to the tip of the connecting body 17 of the displacement magnifying mechanism.

In the initial state, these two sets of piezoelectric elements are parallel to the recording medium 11. The optical pickup 12 is attached to the piezoelectric element via an elastic material 14 such as phosphor bronze. At this time, the optical pickup 120 substrate surface and the recording medium surface 1
The angular change made by 1 is set to θt. In this example, approximately 1
It is 5°.

Quadrupole optical waveguide lens 12 of condensed optical pickup 12
The optical axis 124 of the light 123 emitted from 2 is in the substrate normal force direction 1
It forms an angle between 25 and 0. Therefore, in order to reflect the specific signal light on the recording medium surface 11 and redirect it to the condensing waveguide lens 122, it is necessary to make the optical axis 124 and the recording medium surface 11'% rectangularly intersect. Medium surface 11 and optical pickup 1
The slope ptOt of 2 is approximately the same as θ.

To drive the optical pickup 12 in the focusing direction, a voltage is applied to the piezoelectric element, and each pressure
The plane positions vl and v2 applied to the fK element are changed to keep the optical pickup 120 angle θti constant.

In addition, in the piezoelectric element shown in Figure 16, the pressure of two sheets ↑
Instead of pasting materials or electrostrictive materials together, it is possible to use a material made by pasting one piezoelectric material or electrostrictive material and one elastic body such as phosphorous copper.

However, the pressure that creates the displacement in the transverse direction of the information track 1
Instead of the 1L element 16, a vertical piezoelectric element like the one shown in FIG. 6 may be used.

- In the drive mechanism used in this embodiment as shown in FIG. The optical pickup 12 can be tilted so as to be substantially perpendicular to the . This situation is shown in FIG.

FIG. 7(,) shows that the recording medium surface 71 is δ from the normal position 11.
If it is tilted by 1, the voltage v applied to the piezoelectric element of the long sword
If Ij is smaller than vI in Figure 2, it is 573
The tip of the optical pickup 12 is lifted so that θ1=θ is - δ1, and the optical axis 124 of the condensing waveguide lens 122 is made almost perpendicular to the surface of the recording medium. be able to.

On the other hand, FIG. 71 (?1) shows the case where the recording medium surface 71 is tilted opposite to the case of (a). If the voltage v1'' applied to the long force piezoelectric element is made larger than vl in the wc2 diagram,
The element tends to bend greatly due to this pressure, creating a displacement in the direction of K7j. Due to this displacement, the optical pickup 12 can be tilted significantly (θ2=θt+δ!) so that the optical axis can be made almost perpendicular to the surface of the recording medium.

Here, the voltage v2 applied to the shorter piezoelectric element is kept constant, but the slope can be adjusted by changing v2 as well.

If this tilt correction mechanism is provided in the track cross direction and the track force direction, the tilt of the recording medium surface can be corrected two-dimensionally.

[Example 2] Fig. 8 shows an example @2. The piezoelectric element 15 in the first embodiment is replaced with an electromagnetic drive device composed of a magnetic circuit 82 including a can body and a coil 81.

The optical pickup 12 is moved to the vicinity of the desired information track using this mat-type drive device capable of producing a large displacement, and minute displacements in the track cross direction and focus direction are produced by the piezoelectric element 16.13. These functions are similar to those in the tenth embodiment.

〔Effect of the invention〕

As described above, an advantage of the present invention is that the driving device of an optical pickup is configured using a piezoelectric element or an electrostrictive element, so that the cross-sectional thickness of the piezoelectric element or electrostrictive element can be reduced to 5M.
The drive unit f is smaller than the conventional electromagnetic drive unit.

It can be made thinner.

In addition, the resonant frequency of the conventional tEB-type mechanical drive device that drives the objective lens is several tens of Hz, whereas the resonant frequency of the piezoelectric element or electrostrictive element is 110 Hz.
Since it is 0Hs or more, it also has the effect of making it easier to assemble a servo circuit that performs tracking and focusing using the error signal from the optical pickup.

In addition, IT4 is also used to drive magnetic heads used in magnetic recording devices using piezoelectric elements or electrostrictive elements.
I can be there.

[Brief explanation of drawings]

FIG. 1 is a plan view schematically showing a first embodiment of the optical pickup driving device of the present invention. @2 Figure is a cross-sectional view of a part of the optical pickup driving device of the present invention, showing a driving method in the focus direction. FIG. 3 is a cross-sectional view schematically showing a conventional optical pickup driving device. Surface diagram. FIGS. 5 and 6 (a) and (h) are diagrams showing the structure of a piezoelectric element used in the present invention. FIG. 7(,)(b) is a diagram showing another usage of the focus direction driving device of the present invention. FIG. 8 is a plan view schematically showing a second embodiment of the present invention. 10... Guide 11... Recording medium surface 12... Optical pickup 121... Semiconductor laser 122... Concentrating waveguide lens 123... Luminous flux 124... Optical axis 125... This machine Normal line 13... Piezoelectric element 14... Elastic body 15... Piezoelectric element 16... Piezoelectric element 17... Connecting rod 18... Fulcrum 19... Rotation shaft 31... Objective lens 32 ... Mirror 33 ... Light source 34 ... Luminous flux 351 ... Magnetic circuit 352 ... Magnetic circuit 353 ... Magnetic circuit 561 ... Coil 362 ... Coil 363 ... Coil 37 ...・Objective lens support 41... Substrate 42... Buffer 1-43... Optical waveguide film 44... Waveguide type beam splitter 45... Photodiode 46... Original spot 47... Guide Wave light 51...piezoelectric body 52...electrode 53-polarization direction 54...power source 55...stretching direction 61...piezoelectric body 62...electrode 63...support body 64...polarization direction 65...Power supply 71...Recording medium surface 81...Coil 82...Magnetic circuit A, B, O, T),! , KOI GI H + ENG 1fflK
, L, M, N...Movement direction θt, θ1, δ2...Angle θ between the recording medium and the optical pickup...Angle δ1, δ2... between the normal direction of the optical pickup board and the optical axis Inclination of recording medium surface ■I * v2 * vl' * V""'
Voltage L... Length of piezoelectric element l... Length of piezoelectric element d... Displacement t... Thickness of piezoelectric element or more Applicant: Seiko Epson Co., Ltd. Agent Patent Attorney Mogami Tsutomu 1. ',. 1 bend/12 figure rod 4 Figure (a) Figure 4 ('b) Figure 7 li) Figure 7 (shi)

Claims (5)

[Claims] (1) In a drive device that drives an optical pickup used in a device that writes and reads information by optical means, displacement of the optical pickup is applied to a piezoelectric element or an electrostrictive element (hereinafter collectively referred to as a piezoelectric element). An optical pickup driving device characterized in that the optical pickup is driven by the generated displacement. (2) The optical pickup driving device according to claim 1, wherein the transmission means for transmitting the displacement generated in the piezoelectric element to the optical pickup is provided with a mechanism for magnifying the displacement. (3) The optical pickup driving device according to claim 1, wherein the displacement of the optical pickup in the direction across the information track of the recording medium is caused by at least one piezoelectric element. (4) The displacement in the direction of moving the optical pickup closer to and away from the surface of the recording medium is made by bonding at least one piezoelectric material or electrostrictive material (hereinafter collectively referred to as piezoelectric material), and the lengths are the same or different. 2. The optical pickup driving device according to claim 1, wherein the optical pickup is generated by combining at least two piezoelectric elements and adjusting the voltage applied to each piezoelectric element. (5) A patent claim characterized in that the optical pickup is an optical pickup in which thin film optical elements such as a light emitting element, a light receiving element, a waveguide lens, a waveguide type beam splitter, etc. are integrated in a hybrid manner or monolithically. The optical pickup drive device according to scope 1.