JPS5965491A - Piezo-electric fine displacement device - Google Patents

Abstract

PURPOSE:To eliminate a stick slip making use of the non-linearity of expansion and contraction of a piezo-electric element by a method wherein a pressurizing means is fixed to the base of a fine displacement device. CONSTITUTION:A U type case 36 is made of phosphor bronze and its top and bottom are respectively penetrated and threadingly fixed by a ball press screw 34 and a ball support screw 35. The lower end of the ball press screw 34 is formed into a flat or recessed surface or a notch coming into point contact with a ball 33 while the upper end of said screw 34 is formed into a spherical surface. On the other hand, the upper end of the ball support screw 35 is also formed into a flat or concave surface or a notch coming into point contact with another ball 33 while the lower end of said screw 35 is formed into a driver slot to be driven into or back for fine adjustment. Therefore both ends in the expansion and contraction direction of a piezo-electric element 3 are held by a point contact with the balls 33 to be pressurized in said direction by the ball support screw 35 when it is driven into. A cord 48 is connected to the piezo-electric element 3 through a connector 32 while the space between the piezo-electric element 3 and the U type case 36 is filled with electric insulating rubber 38. In such a constitution, an electric leak due to a stain or scratch of the piezo-electric element 3 may be prevented from occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to minute displacement 1q using a piezo element.

When a voltage is applied to a piezo element, it expands and contracts in minute dimensions, so a minute displacement fIL that utilizes this has been put into practical use.

FIG. 1 shows an example of a conventional micro-displacement device configured to focus a microscope using a piezo element.

1 is an objective lens of a microscope, and 2 is a workpiece that is an object to be focused. A vertically movable block 7 on which the work 2 is placed is supported by a fixed block 9 by two leaf springs 8. The piezo element 3 is interposed between the fixed block 9 and the vertically movable block 7, and is connected to the high voltage DC power supply 1.
0, when a driving voltage 4 is applied, it expands and contracts as shown by the arrow 5, causing the vertical movement block 7 to move up and down. In response to this, the ↓ diwork 2' is moved down as shown by arrow 6 to perform focusing.

'Figure 2 (Al is a plan view of the above piezo element 3, the same figure (
Bl is the same front view. The piezo element 3 used in this example is a multilayer piezo, and the positive electrode 21 shown by the dotted line
A plurality of piezo plates 231 are sandwiched between the main electrode 22 shown by the solid line and a voltage is applied to the expansion/contraction displacement arrow 5.
It is a structure that allows you to do this.

The upper end of the piezo element 3 contacts the vertical movement block 7 via a ball point 24, and the lower end is fixed to the fixed block 9 via 25 identification screw members.

In this conventional example, 50 piezo plates 23 of 5M square and 0.5 μm thick are laminated and bonded together. When a direct current of 5 oov, i is applied to this multilayer piezo 3, an expansion/contraction displacement as shown in FIG. 3(A) is exhibited. The characteristics of the piezo element used in this conventional example are as follows.

The load capacity is 7 Ky. The side load is relatively large compared to the size of 5W square.

The extension stroke when applying 500V is 25 μm, which is relatively small, but the resolution of minute displacement is very good, for example 0
．． Approximately 0.0 with a voltage change of 1V. [105μm elongation 11rv
c.

In addition, the displacement response speed is fast and it is easy to move with 'K)lz.

In summary, the advantage of the piezo element is that it is a small member and can perform minute displacements at high speed and with relatively high load resistance.

10,000, multilayer piezo elements used in conventional micro-displacement devices have (a) non-linearity of expansion and contraction, (damage at the 1 m contact point, and (/→ applied voltage There are technical problems such as electrical leakage.

FIG. 4 is an explanatory diagram of the above-mentioned (a) non-linearity of expansion and contraction.

When a voltage is applied to expand and contract the multilayer piezo element 3 while it is fixed to the bottom k1m constant block 9, the pole point 24 provided on the top thereof does not necessarily rise vertically as shown by arrow C, but for example, as shown by arrow C. It rises obliquely, and it is not uncommon for its fine dimension E to be about 0.5 shoes. Such non-linearity is thought to be due to uneven thickness and material unevenness of the individual piezo plates. Figure 5 is an explanatory diagram schematically showing the nonlinearity of expansion and contraction mentioned above.
It changes into various shapes as shown in the figure. Therefore, the top surface 4Cfik of the piezo element 3 + the attached ball point 24
is in contact with the vertical movement block 7, this contact S becomes stick-slip.

Figure 3 (Bl is an enlarged view of the state when stick-slip r occurs near the F part of the expansion/contraction curve of Figure 3 (At).FjIQ is the displacement curve of the piezo element 3, and the broken line R is the locus of the vertical motion block 7. In this way, due to the non-linearity of the expansion and contraction of the piezo element, the vertical motion block 7
Not only does the movement of the piezo element 3 lack smoothness, but also a moment 27 (see FIG. 2 (Bl) is applied to the piezo element 3, causing fatigue damage to the piezo element 3.

The damage at the adhesive point (q) mentioned above is related to the structure in which the piezo element 3 is made by laminating and bonding a large number of piezo plates 23 with ceramic cracks, and when subjected to shear force, sliding displacement occurs between the piezo plates. For this reason, the piezo elements used in the conventional five-position micro-displacement device described above are easily damaged by shearing during assembly and adjustment, and even after one set is molded, the piezo elements used in the conventional five-position micro-displacement device are susceptible to shearing. It is often damaged.

The leakage of the voltage applied to Q4 mentioned above is a problem related to the fact that a relatively high voltage, for example 500V, must be applied between the positive electrode 21 and the negative electrode 22 shown in FIG. Even the slightest dirt or scratch on the element 3 tends to cause IJ-induced damage.

In order to prevent this corrosion, electrically insulating paint is applied, but the effect is not perfect.

Particularly, as mentioned above, when the piezo element suffers fatigue damage or shear damage, there is a risk that the electrodes 21 and 22 may be short-circuited, which is very dangerous.

The present invention has been made in view of the above circumstances, and there is no risk of stick-slip occurring due to the non-IS nature of expansion and contraction of the piezo element, there is no risk of shear damage to the piezo element, and there is no risk of short circuit due to damage. The purpose of the present invention is to provide a piezo-type micro-displacement device without

In order to achieve the above objects, the piezoelectric micro displacement device of the present invention includes a piezo element, a member that makes point contact with both ends of the piezo element, and means for pressurizing the piezo element via the point contact member. The present invention is characterized in that the pressure means is fixed to the base of the minute displacement device, which is different from the means for transmitting the expansion and contraction position of the piezo element through the pressure means described above.

Next, a simple embodiment of the present invention will be described with reference to FIGS. 6 to 9.

FIG. 6 shows an embodiment of the piezo type minute displacement device of the present invention, in which an objective lens 1, a workpiece 2, a vertically moving block 7, and a plate spring are shown with the same drawing reference numbers as the conventional device (FIG. 1). 8, the identification block 9, and the high voltage DC power supply 10 are the same or similar components as in the conventional device, and the main difference from the conventional device is the support structure of the piezo element 3. FIG. 7 shows a plan view of the failure structure of the piezo element 3, FIG. 8 shows a front view, and FIG. 9 shows a side view.

The present invention provides point contact members at both ends of the piezo element.

In this embodiment, ball seats 32 are provided at the upper and lower ends of the piezo layer 3, respectively. N L/h The balls 33 are brought into opposing contact with the respective ball receiving surfaces.

The present invention provides means for pressurizing the piezo element via the point contact member.

In this embodiment, the U-shaped case 36 is made of phosphor bronze.
A ball support screw 35 for abutting the ball 33 is screwed through the lower side thereof, and a ball holding screw 54 is screwed through the upper side thereof.

The lower end of the ball retaining screw 34 is formed flat, concave or notched so as to make point contact with the ball 36, and the upper end thereof is formed spherically.

The upper end of the ball support screw 55 is formed flat, concave or notched so as to make point contact with the ball 33, and the lower end thereof is formed with a driver groove so that it can be screwed back and adjusted.

The exviezo element 3 is held in point contact with the balls 33 at both ends thereof in the direction of expansion and contraction, and when the ball support screw 35 is tightened, pressure is applied in the direction of expansion and contraction.

When carrying out the present invention, if a U-shaped member 36 made of a material with spring elasticity such as phosphor bronze is used as in this embodiment, the piezo element 3 is sandwiched between both parallel sides of the U-shaped member 36 and then applied. It is easy to apply pressure, and due to the elasticity of the U-shaped member, the pressure can be applied uniformly regardless of the expansion and contraction of the piezo element 3.

As described above, the U-shaped case 36, which constitutes a means for pressurizing the piezo element 3 through the point contact member and is the pressurizing means for the upper part, is attached to the fixing block 9 by means of a set screw 43.

X: -/L/Support and tighten 65 to apply a pressure of about 3~ to the piezo element. In this pressurization operation, the piezo element 3 is included! ! The total length of the cup unit can be finely adjusted by ±100 μm. The cord 48 is connected to the piezo element 3 via the connector 37,
The space between the piezo element 3 and the U-shaped case 36! ///
Fill with JtL electrical insulation rubber 3B. With this VL configuration, it is possible to prevent electrical leakage due to dirt or scratches on the piezo element 3.

FIG. 10 is an explanatory diagram schematically depicting the action of a piezo-type minute displacement device. IAI in this figure represents a conventional device in which the lower end of the piezo element 3 is fixed to a fixed base 9;
1 represents a state in which both ends of the piezo element 3 are held between point contact portions 40. 39 is the center line when the piezo element 3 is contracted.

In the conventional device + AI, the lower end of the piezo element 3 is fixed to the fixed block 9, so when the piezo element 6 is warped due to elongation, a moment 27 is applied to the piezo element 3.
In addition to causing breakage and causing eccentricity 2 at the tip,
6, resulting in stick-slip. On the other hand, in the device of the present invention (Bl), both the upper and lower ends of the piezo element 3 are held in point contact, and the upper end 41 and lower end 42 of the piezo element 3, which are supported via a single point contact part 40, can both rotate. Since it is not constrained, it does not generate a moment,
Therefore, there is no risk of the piezo element 3 breaking or being damaged. Therefore, there is no risk of electrode short-circuiting due to breakage. Also, □
When the upper end point contact portion 41 is guided along the center #39, it moves up and down without difficulty. Therefore, there is no risk of stick-slip occurring.

11 and 12 show an embodiment different from the above, in which FIG. 11 is a plan view and FIG. 12 is a sectional front view. This embodiment differs from the previous embodiment in the following points.

(1) A notch 56a is formed on the upper side of the U-shaped case 36 to facilitate elastic deformation in this part, and a ball seat 45 is formed at a distance hLt from this notch 56a, and at a point a distance L2 from the notch 56a. Pusher 49 is screwed on. As a result, the cantilever-shaped member 44 forming the upper side of the U-shaped case 36 acts as a lever, and the expansion and contraction of the piezo element 3 is amplified by a factor of L2/L1.
9 pushes a driven member (not shown).

(II) A cover part 361) is provided on the U-shaped case 36 to surround the outer periphery of the piezo element 3. ! The entire gap is filled with electrically insulating rubber 38. This prevents electrical leakage from occurring due to dirt or scratches on the piezo element 3! It is more completely prevented than in lK.

As described in detail above, when the present invention is applied, there is no risk of a sudden slip occurring due to the non-m-line property of the piezo element, and shear damage to the soil piezo element as well as short circuits caused by shear damage can be prevented. It has excellent practical effects.

[Brief Description of the Drawings] Figures 1 to 5 show a conventional piezoelectric micro displacement device, with Figure 1 being a front view and Figure 2 (Al being a plan view of the piezo element, tBl being the same). Front view, Figure 3 (Al is a diagram showing the operating characteristics of the piezo element, the same figure (Bl is an enlarged detailed view of the vicinity of the F part of Al, Figure 4 is an explanatory diagram of the expansion and contraction operation of the piezo element, Figure 5 (Al, (Bl) is an explanatory diagram schematically representing the deformation of the piezo element. Figures 6 to 8 show an embodiment of the present invention, Figure 6 is a front view, and Figure 7 is a front view. is a plan view of the piezo element and its supporting member, FIG. 8 is a front view of the same, and FIG. 9 is a J-plane view of the same. yc explanatory diagram,
FIG. 101(B) is an explanatory diagram schematically showing the operation of the piezo micro displacement device of the present invention. FIG. 11 is a plan view of an embodiment different from the above, and FIG. 12 is a front view of the same. 3...Piezo element, 9...Fixed professional...Yu, 23
... Piezo plate, 32... Ball catch, 33... Ball, 64... Pole holding screw, 35... Ball clamp screw, 66... U-shaped case, 45... Pole catch, 49...butsusha. zu樗゛ノ 06 2nd 田' 3rd round ya 4I! 1 sai 5 (2) (A) (is) sai 6 (2) off 1!1 o grs sai q2 imaginary 455 sai 1lIii ot2rl! J

Claims (1)

[Scope of Claims] 1. A piezo element, a member that makes point contact with both ends of the piezo element in the direction of expansion and contraction, means for pressurizing the piezo element via the point contact member r, and the point contact member. 1. A piezo-type micro-displacement device comprising means for transmitting the expansion and contraction displacement of a piezo element through the piezo element, and the above-mentioned pressurizing means is fixed to a base of the micro-displacement device. 2. The piezo type minute displacement device according to claim 1, wherein the pressurizing means uses a U-shaped member having spring elasticity.