JPS61122940A - Optical system lens fine adjusting device - Google Patents

Abstract

PURPOSE:To make a fine change of the focus distance easy and to decrease power consumption by fitting a lens to a central part of a sticking piezoelectric vibrator sticking a gear-shaped piezoelectric ceramic on both surfaces of a metallic plate 6 and supporting and fixing the metallic plate of the outer circum ference part. CONSTITUTION:A lens 8 is fitted at a metallic plate 6 of the central part of a sticking piezoelectric vibrator sticking gear-shaped piezoelectric ceramics 4 and 7 at both surfaces of a metallic plate 6, and the metallic plate 6 of the outer circumference part is supported and fixed to an external frame 9. The voltage is impressed to piezoelectric ceramics 4 and 7 of a gear-shaped sticking piezoelectric vibrator, one side is extended in the radial direction, other side is constructed to contract, and then, a gear-shaped sticking vibrator is flexible, and the lens 8 fitted to a central part is finely displaced in the flexible direction. When a voltage is impressed in the reverse direction, the lens 8 is displaced in the reverse direction. Because of such a gear-shaped piezoelectric vibrator, an electric capacity of the area ratio goes t be small and power consumption goes to be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION The field of application of the present invention is an optical precision device or an autofocus camera,
The present invention relates to the structure of an optical system lens fine movement device that slightly shifts the focal length of an optical system such as a video camera.

2. Description of the Related Art Generally, as a means for changing the focal length, there is a method of changing the position of a lens by using so-called electromagnetic force, which uses a permanent magnet and a coil. In order to generate minute vibrations in order to obtain minute displacements of the lens and autofocus force signals using this method, positioning accuracy is difficult and the structure becomes complex.

On the other hand, there are examples in which the position of the lens is slightly changed using a vibrator using a piezoelectric material such as a piezoelectric organic film, but tension must be applied to support the weight of the lens, and it is difficult to make large vibrations. be. One possible way to solve the above problems is to use piezoelectric ceramics. As shown in FIG. 5, annular piezoelectric ceramics 1 and 2 having polarization axes in the thickness direction are bonded together with an annular metal plate 3 in between to form a vibrator. Such an annular structure has strong mechanical strength and enables precise positioning.

Problems to be Solved by the Invention When an annular structure is used, the area of the piezoelectric ceramic becomes large, and as a result, each state as a capacitor becomes large, and ineffective power is consumed.

SUMMARY OF THE INVENTION An object of the present invention is to provide an optical system lens fine movement device that can stably and easily drive a lens to minutely change the focal length, and that consumes less power during driving.

Means for Solving the Problems According to the present invention, two flat plates of piezoelectric ceramic having a gear structure in which a part of the ring is cut out and at least two cantilevers are formed in the same shape. A laminated piezoelectric vibrator is used, which is laminated on both sides of a thin metal plate with a smaller inner diameter and a larger outer diameter than the piezoelectric ceramic, and a lens T [glued to the metal plate on the inner periphery, and a metal plate on the outer periphery]. is supported and fixed to a block made of metal, etc., and a voltage is applied between the metal plate of the laminated piezoelectric vibrator and the piezoelectric ceramic ζts, whereby the laminated piezoelectric vibrator is bent and the lens attached inside is slightly displaced. It is configured to allow

The area of the working electrode is smaller than that of an annular electrode, and the capacitance can be reduced. Moreover, an amplitude equivalent to that of a circular ring can be obtained.

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

First, an annular bonded piezoelectric vibrator as shown in FIG. 6 is created. That is, a circular metal plate is sandwiched between two circular piezoelectric ceramics having polarization axes in the thickness direction, and bonded with an adhesive such as epoxy resin. Next, as shown in FIG. 1, a part indicated by A is cut out from the annular bonded piezoelectric vibrator, and a gear-shaped piezoelectric ceramic 4 on which a plurality of cantilevers 6 are formed is attached to a metal plate 6. A laminated piezoelectric vibrator is constructed on both sides.

FIG. 2 is a longitudinal sectional view of an optical lens fine movement device using the gear-shaped bonded piezoelectric vibrator. A lens 8 is attached to the metal plate 6 at the center of a bonded piezoelectric vibrator in which gear-shaped piezoelectric ceramics 4 and 7 are bonded to both sides of a metal plate 60, and the metal plate 6 at the outer periphery is supported and fixed to an outer frame 9. . Applying a voltage to the piezoelectric ceramics 4 and 7 of the gear-shaped laminated piezoelectric vibrator,
If one side extends in the radial direction and the other side contracts, the gear-shaped bonded piezoelectric vibrator is deflected, and the lens 8 attached to the center is slightly displaced in the direction of the deflection. Furthermore, when a voltage is applied in the opposite direction, the lens 8 is displaced in the opposite direction.

Further, when an alternating current voltage is applied, the lens 8 is displaced as shown by the arrow shown in FIG. 3, and the focal position of the lens 8 can be changed periodically.

When the structure shown in FIG. 2 is adopted according to the present invention, the electrode area is smaller than that of the annular piezoelectric vibrator shown in FIG.

As a result, the area-to-area capacitance becomes smaller, resulting in less power consumption.

In addition, since it has a structure similar to that supported at both ends, it has the characteristic of being able to obtain an amplitude equivalent to that of an annular piezoelectric vibrator.

- Since the force support structure is the same as that of the toroidal piezoelectric vibrator, Z
・Features stable vibration characteristics and good displacement positioning accuracy due to its good J-symmetry.

As another embodiment of the present invention, similar effects can be expected when the annular portion is disposed at a portion other than the center, as in the structure shown in FIG. 3 or 4. However, in FIG. 3, a diagonally shaded portion 1o outside from the annular portion of the piezoelectric ceramic 4
The polarization direction of the inner gear-shaped grid area 11 must be reversed, or if the polarization directions are the same, the voltages of the hatched area 1o and the grid area 11 must be applied in opposite directions. No. The structure of FIG. 4 also requires operations similar to those of FIG. 3.

Effects of the Invention According to the optical system lens fine movement device of the present invention, the optical system lens can be driven with a large displacement with good positioning accuracy, and moreover, power consumption is low.

[Brief explanation of drawings]

FIG. 1 is a plan view of a piezoelectric vibrator used in an optical lens fine movement device according to an embodiment of the present invention, FIG. 2 is a sectional view of the same device, and FIGS. 3 and 4 are in an embodiment of the invention. A plan view of the piezoelectric vibrator and FIG. 6 are perspective views showing the piezoelectric vibrator having an annular shape as a whole. 4, 7...--piezoelectric ceramic, 6...metal plate, 8...lens, 9...outer frame. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure m3

Claims (3)

[Claims] (1) Two piezoelectric ceramic elements each having at least two gear-shaped cantilevers formed by cutting out a part of a ring having a polarization axis in the thickness direction, and a thin metal plate. An optical lens fine movement device comprising a laminated piezoelectric vibrator in which the laminated piezoelectric vibrators are laminated and bonded together, a metal plate on the outer circumference of the laminated piezoelectric vibrator is supported and fixed, and an optical lens is attached to the metal plate on the inner circumference. . (2) The optical system lens fine movement device according to claim 1, wherein two piezoelectric ceramic elements are bonded together and the metal plate is bonded to one end surface to form a bonded piezoelectric vibrator. (3) Claim 1, characterized in that the laminated piezoelectric vibrator is constructed by bonding one piezoelectric ceramic and a metal plate.
Optical system lens fine movement device as described in .