JPS62164234A - Optical system driver - Google Patents

Abstract

PURPOSE:To drive an optical system with high accuracy by forming a support member into a curved arm shape and providing a piezoelectric element into a space enclosed by said support member. CONSTITUTION:When the voltage is impressed to a piezoelectric element 101, the element 101 has a mechanical strain and is displaced in the direction A-A'. This displacement is transmitted to the direction (a) of a frame body part 102a via a head 103 attached at the tip part of the element 101. Then the displacement degree is mechanically amplified by the part 102a. In other words, a point of force produced by the head 103 is set closer to the fulcrum side than the position of a hinge part 102d serving as an action point with the position of a hinge part 102e defined as a fulcrum. Thus the displacement degree of the element 101 is amplified by the action of levers and transmitted to a support member 102. The end face of the part 102a is fixed to a base 111 and therefore an optical system holder attachment part 102b is displaced in the direction (b), e.g., the tracking direction with a shaft hole 102c defined as the center of a curvature radius. The distance between the action point and the the hole 102c is smaller than that between the part 102a and the hole 102c. Therefore the displacement of the element 101 is amplified further at the part 102b.

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to an optical system drive device, particularly in an optical information recording/reproducing device such as an optical disk device, a magneto-optical disk device, or a digital audio device, in which a light beam is directed onto an information recording medium. This invention relates to an optical system driving device that focuses light. (Prior Art) In general, in an optical information recording/reproducing device such as an optical disk device, in order to read the information recorded in the information bits (1 to 2 μm in width and 1 to 3 μm in length) of an information recording medium, first, , a light beam (usually a Lede beam) is focused on a spot 4\\g by an optical system such as an objective lens, and irradiated onto the information bit.At this time, depending on the presence or absence of information, reflected light or transmitted light from the information recording medium By detecting this change with a photodetector, a reproduction signal corresponding to the information bit can be obtained. It is extremely important that the tiny spot of the light beam always accurately scans the FF information and columns.For this purpose, autofocus and eccentricity of the information recording medium are used to correct focal shifts caused by warping of the information recording medium. Auto-tracking is required to correct the irradiation position deviation due to etc.Then, as a means to realize this auto-focus function and auto-tracking and tracking functions, the optical system is supported by a spring-like structure and consists of a coil and a magnetic member. A method using electromagnetic force generated by a magnetic circuit is known. Fig. 4 is a perspective view showing a conventional optical system drive device having an autofocus function and an autotracking and kinging function. In this figure, 1 and 2 are A magnet and a yoke constitute a magnetic circuit for focusing, and 3 and 4 are magnets and a yoke that constitute a magnetic circuit for tracking.5 is an optical system holder equipped with an objective lens 6 as an optical system; Fixed to both opposing sides of the optical system holder 5

The two coils 7.8 are arranged in the focusing and tracking magnetic circuits, respectively. Reference numerals 9 and 10 are support legs that hold the optical system holder 5 movably in the focusing direction, 11 and 12 are support springs that hold the optical system holder 5 movably in the tracking direction, and the relay plate They are connected via 13. ] 4 is the magnet 1, 3.
Yokes 2, 4, optical system holder 5, support spring 9.10.1
This is a base on which 1.12 etc. are installed. In the device configured as described above, when a current is applied to the coil 7.8, each magnet 1°3 and yoke 2
, 4, and the objective lens 6 attached to the optical system holder 5 through the support springs 9, 10, 11, and 12 can be focused and tracked by the interaction due to the electromagnetic force generated by the magnetic [self 1 path]. can. (Problems to be Solved by the Invention) However, the above-mentioned leaf spring-shaped support spring 9.10.
11.12, each support spring 9, No. 11.1 is used when tracking and focusing at high frequency due to its characteristics.
There is a problem in that high-precision tracking, focusing, and focusing cannot be performed due to the occurrence of sub-resonance in the second lens. On the other hand, in order to solve the above problem of sub-resonance, an apparatus in which an optical system is supported by a supporting member rotatably provided about a predetermined axis has been proposed in Japanese Patent Publication No. 30017/1983. However, in this device as well, the optical system is driven by electromagnetic force between a magnet and a coil, so the structure of the magnetic circuit etc. is complicated and the device tends to be large. The present invention was made in order to solve the above-mentioned problems of the conventional example, and it is an object of the present invention to provide an optical system driving device that can drive an optical system with high precision, and with a simple and simple configuration. be. (Means for Solving the Problem) As a means for solving the problem, the present invention provides an optical system drive device that includes a support member that is rotatably provided around a certain axis, and a support member that is rotatable around a certain axis. an optical system supported at a position spaced apart from the axis so that its optical axis is almost parallel to the axis, and a piezoelectric element that applies a driving force in the direction of rotation to the support member; The gist is that the support member is formed into a curved arm shape, and the piezoelectric element is disposed in a space surrounded by the support member. (Example) Hereinafter, the present invention will be explained in detail with reference to an illustrated example. FIG. 1 is an exploded configuration diagram showing an optical system driving device according to the present invention. In this figure, 101 is a laminated piezoelectric element, and the piezoelectric element 101 is constructed by laminating a ceramic 101b formed by printing and laminating extremely thin internal electrodes 101m on a thin green sheet. (See Figure 2). 101c is an insulator provided on the side surface between each ceramic plate 101b, and terminals 101d and 101e are provided on the outside thereof.
An external electrode 101f is provided. Reference numeral 102 denotes a U-shaped arm-shaped support member that supports the optical system, and a frame portion 10 formed on one side of the support member 102
A piezoelectric element 101 is disposed inside the piezoelectric element 2a, and the piezoelectric element 103 provided at the tip of the piezoelectric element 101 comes into line contact with the frame body part 102m. The other side of the support member 102 is formed along the outer circumferential surface of a frame portion 02a on which the piezoelectric element 101 is disposed, and a cylindrical optical system holder attachment portion 102b is further formed at its tip. Reference numeral 104 denotes a cylindrical optical system holder. An objective lens 105 is attached to the optical system holder 104 as an optical system. A focusing coil 106 is arranged on the outer circumferential surface, and a sliding friction Coated with Teflon resin to reduce resistance. The optical system holder 104 is attached to the optical system holder mounting portion 102 of the support member 102.
b, so as to be slidable in the optical axis direction of the objective lens 105. 107 is a shaft hole 102c of the support member 102
The bearing 107 is inserted from above into the
It is locked by a fixing plate 109 attached to the upper part of the support member 102 at 08. 110 is a bearing provided on the base 111, and the bearing 110 is inserted into the shaft hole of the support member 102]02
Insert it into c from below. The support member 102 is rotatably supported by point contact with a bearing 107 . In the front, the end portion of the frame portion 102a is fixed to the base 111 with screws 112 and 113. 114 is a cylindrical magnet placed on the base 1]1,
The optical system holder mounting portion 102b of the support member 102 is located within the magnet 114. 102d. 102. and 102f are hinge portions formed on the body portion 102a of the support member 1020, respectively. The optical system driving device according to the present invention is configured as described above, and first, when tracking is performed, the terminal 101d,
Piezoelectric element via 101e and external electrode 101f]01
Apply voltage to. Then, each laminated ceramic 1
Mechanical strain occurs in 01b, causing a displacement in the A-A' force direction. This displacement is caused by the piezoelectric element 1 as shown in FIG.
It is transmitted to the tip end portion of 01 through l-' 103 in the a direction of the frame body portion 102a. The transmitted displacement amount of the piezoelectric element 101 is mechanically amplified by the frame portion 102a. That is, with the position of the hinge part 102e as a fulcrum, the point of force exerted by the head 103 is closer to the fulcrum than the position of the hinge part 102d, which is the point of action, and therefore, due to this lever principle, the amount of displacement of the piezoelectric element 01 is amplified, and the amount of displacement of the piezoelectric element 01 is amplified and 10
2 can be conveyed. On this occasion. Since the end face of the frame portion 102m is fixed to the base 11, the optical system holder mounting portion 102b formed at one end of the supporting member 02 has a radius of curvature centered around the shaft hole 102C.
direction (tracking direction). Here, since the distance between the above-mentioned point of action (position of the hinge part 102d) and the shaft hole 102C is shorter than the distance between the optical system holder mounting part 102b and the shaft hole 102C, the piezoelectric element 10
The displacement transmitted from 1 is further amplified at the optical system holder mounting portion 102b. For example, if the amount of displacement transmitted from the piezoelectric element 101 to the frame portion 102a of the support member 02 is 1
If it is 0 to 20 μm, the amount of displacement at the optical system holder mounting portion 102b will be approximately several hundred μm. In addition, the pressure [element 101
By turning off the voltage applied to the support member 1
02 returns to the original state. Advantages of using the laminated piezoelectric element include that it can be made light, thin, short, and compact, has high electrical-mechanical energy conversion efficiency, consumes low power, and can be driven with high precision. Here, the support member 102 is formed in the shape of a curved arm, and the piezoelectric element 101 described above is disposed in the space surrounded by the support member 102, so that the entire device can be constructed in the form of a condominium. Next, when performing focusing, the optical system holder 104
Due to the magnetic interaction between the magnetic field generated by applying a current to the coil 106 provided on the outer peripheral surface of the magnet 114 and the magnetic field generated by the magnet 114. The optical system holder 104, which is slidably disposed on the optical system holder mounting portion 102b, is driven in the optical axis direction of the objective lens e105. At this time, the outer peripheral surface of the optical system holder 104 is coated with Teflon-based resin, and the inner peripheral surface of the optical system holder mounting portion 102b is also mirror-finished to reduce sliding resistance. Therefore, a smooth 7-o-kashi/g is possible. Further, although this embodiment is an example in which the present invention is applied to an optical system drive device of an optical disk device, it is obvious that the present invention can also be applied to other optical devices such as a shape detection device and a radar processing machine. Incidentally, in the above-mentioned embodiment, the case where only the objective lens is driven as an optical system has been explained, but it is also applicable to the case where the entire optical system including a light source etc. is driven. (Effects of the Invention) As explained above, the optical system driving device according to the present invention performs tracking using the displacement caused by mechanical distortion of the piezoelectric element, and therefore can drive the optical system with high precision with a simple configuration. be able to. Further, since the support member is formed into a curved arm shape and the piezoelectric element is arranged in the space surrounded by the support member, the device can be made smaller.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an exploded state of an optical system driving device according to the present invention, FIG. 2 is a cross-sectional view showing a laminated piezoelectric element, and FIG. 3 is a main part of the optical system driving device according to the present invention. FIG. 4 is a perspective view showing a conventional optical system driving device. 101... Piezoelectric element, 102... Support member, 102
a... Frame body part, ]02b... Optical system holder mounting part,
102c... Shaft hole, 104... Optical system holder, 10
5...Objective lens, 106...Coil, 107,1
10... Bearing% 111... Base, 114... Magnet.

Claims (1)

[Claims] a support member rotatably provided around a certain axis;
an optical system supported at a position apart from the axis of the support member so that its optical axis is substantially parallel to the axis; and a piezoelectric element that applies a driving force in the rotational direction to the support member; An optical system driving device in which a support member is formed into a curved arm shape, and the piezoelectric element is arranged in a space surrounded by the support member.