JPS63120051A - Precision displacement generator - Google Patents

Abstract

PURPOSE:To obtain an optional displacement by energizing a piezo-electric element with a servo system and allowing a control circuit to control clamp means with the predetermined timing synchronous with the switching timing of the reference voltage. CONSTITUTION:Iron pieces 15, 16 are connected to both sliders 1, 2 via plate springs 17, 18 respectively. Electromagnets 9, 10 are arranged to face these iron pieces 15, 16 in their movement ranges. The electromagnets 9, 10 absorb the iron pieces 15, 16 when energized and clamp both sliders 1, 2 respectively. Energization of both electromagnets 9, 10 is performed by a power supply 8 via the contact points of relays 19, 20, and the relays 19, 20 are controlled by a control circuit 6 via the voltage V1, V2. The control circuit 6 outputs the voltage V1, V2 with the predetermined timing and in addition outputs the reference voltage e1 and e2 in turn with the predetermined timing, which is inputted to the plus terminal of an adder 5.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an apparatus that accurately generates displacement for precision machining or calibration of measuring instruments.

(Prior art) Conventional displacement generators of this type include those that perform feedback control while measuring the amount of displacement with a laser interferometer;
There are those that use a pulse motor and convert the rotation thereof into linear motion using a ball screw or the like, and those that utilize the distortion of a piezoelectric element.

(Problems to be Solved by the Invention) The device using the laser interferometer has a complicated structure and is not easy to operate. In those using a pulse motor, it is difficult to accurately reduce the step width, and only a fixed step width of about 5 to 10 μm can be obtained. Further, in the case of using a piezoelectric element, strain, that is, displacement corresponding to the applied voltage can be obtained continuously, but the disadvantage is that the operating range is extremely narrow.

The present invention provides a displacement generating bag that does not have these drawbacks, namely, 0. Precise displacement in the operating range of several tens of I in an adjustable step of about 01 to 1 μm.

Moreover, it is intended to be easily generated.

(Means for Solving the Problems) For the above purpose, the present invention utilizes strain in a piezoelectric element as a displacement generation source. Two piezoelectric elements arranged in parallel
The slider is installed across two sliders, and both sliders are alternately clamped in synchronization with the expansion and contraction, and this is repeated.

The amount of relative movement between both sliders caused by one strain is controlled to a constant value by a servo system.

That is, the amount of relative movement is measured by a micrometer installed on the slider, this is compared with a set value, and the piezoelectric element is energized based on the difference, thereby controlling the amount of distortion of the piezoelectric element to a predetermined value. 6 (Function) When one slider is clamped, a voltage is applied to the piezoelectric element, which causes distortion. For example, when the piezoelectric element is expanded, the other slider moves forward by the amount of expansion. Here, after clamping the other slider and releasing the clamp on one slider, when the voltage application to the piezoelectric element is released, the piezoelectric element returns to its original dimensions, and the other slider moves forward by the amount restored accordingly. do. Thereafter, when this is repeated, the piezoelectric element expands and contracts repeatedly.

Both sliders will move forward. The amount of expansion and contraction of the piezoelectric element is measured with a micrometer and compared with the set value, and the piezoelectric element is energized based on the difference between them. Therefore, the step lJ is a constant value determined by the set value, and the total displacement is determined by the number of repetitions. It will be doubled.

(Example) FIG. 3 shows an embodiment of the invention.

The first guide 11.12 is fixed parallel to the base 21.
The slider 1 and the second slider 2 are each supported so as to be able to move linearly in the direction of arrow A or vice versa. A piezoelectric element 3 is provided on arms 13 and 14 projecting from both sliders 1 and 2, respectively, with both ends thereof fixed. Second
A pickup 4 as a micrometer is fixed on the slider 2, and its probe 4a is in contact with a reference surface 13a provided on an arm 13. Iron pieces 15 and 16 are connected to both sliders 1.2 via leaf springs 17 and 18, respectively. An electromagnet 9.degree. 10 is arranged opposite to the iron piece 15.degree. 16 within its movement range. electromagnet 9,
10 attracts iron pieces 15 and 16 when it is energized, and clamps both sliders 1 and 2, respectively.

As shown in FIG. 1, the magnets 9 and 10 are energized from the power source 8 through the contacts of the relays 19 and 20, which are controlled by the voltages V□ and v2 from the control circuit 6. be done. The control circuit 6 outputs the voltages V and v2 at predetermined timings, and also outputs the reference voltages e1 and e2 while switching at predetermined timings, which are input to the plus terminal of the adder 5. The output of the pickup 4 is input to the negative terminal of the adder 5.

The output terminal is connected to the piezoelectric element 3 via an integrating circuit 7.

Next, the operation of the device will be explained. At time ○ in FIG. 2, the voltage V1. Since V2 is both at the H level, the contacts of relays 19 and 20 are both on, both electromagnets 9 and 10 are energized, and both sliders 1 and 2 are in a clamped state. At this time, the reference voltage e, =O is output from the control circuit 6, and the piezoelectric cord 3 is not distorted.

At time t□, the voltage V□ becomes O, the contact of the relay 19 is turned off, the electromagnet 9 is deenergized, and the slider 1 is unclamped. At this time, since the piezoelectric element 3 is not distorted, both sliders 1 and 2 are stopped at the start position.

At time t2, the reference voltage is switched to e□ (kiO). This reference voltage e□ is applied to the adder 5. The voltage is applied to the piezoelectric element 3 via the integrating circuit 7, causing the piezoelectric element 3 to expand in the direction of arrow A. The clamped state of the slider 1.degree. 2 is the same as at time t1, and since only the slider 2 is clamped, the slider 1 moves forward in the direction of arrow A by the amount of expansion .delta.1 of the piezoelectric element 3.

By the way, the amount of elongation δ is δ□” (et 'Kt / jWCR) / (1
” (Kt 4z / j'jCR)) K1: Voltage-displacement conversion coefficient of piezoelectric element 3; 2: Displacement of pickup 4-
Voltage conversion coefficient R: Resistance C of integrator 7: Capacitor ω of integrator 7: Angular frequency, and since ω=O in steady state, δ□=
2, and the voltage-displacement conversion constant of the piezoelectric element has a displacement δ1 that is independent of the force, thereby eliminating the effects of hysteresis and the like of the piezoelectric element.

Moreover, if an intensifier with a large increase rate A is used in place of the integration circuit 7, the expansion amount δ1 becomes δi=e,/(K2+1/□A), which is also δ
, = eyo/to2, and a similar result is obtained.

The precise standard displacement (step width) expected due to the expansion of the piezoelectric element 3 is δ. Binding, corresponding to pick-up 4
The output voltage of e. Then, K z = e o /δ.

(v/μm).

δ1== (a, /e,) ・δ.

Then, the reference voltage e is set to step width δ. The value e.

, the amount of expansion δ of the piezoelectric element 3 is the step width δ. is equal to That is, at this stage, the slider 1 takes steps rlJδ in the direction of arrow A. This means that we have made some progress.

At time t, the voltage V returns to H level, and both sliders 1 and 2 are clamped again.

When changing the time, only the voltage v2 becomes O, and the slider 2 is unclamped, but since the voltage remains applied to the piezoelectric element 3, the piezoelectric element 3 remains expanded, and both sliders 1. 2 has not moved from its position at time t.

At time t, the reference voltage is switched from e to e2=0. As a result, the piezoelectric element 3 returns from the expanded state. That is, if the expanded state is used as a reference, δ□ will be reduced. With this reduction, the unclamped slider 2 moves forward in the direction of the arrow.

At time 1G, the voltage V2 again goes to H level, clamping both sliders 1 and 2, and at time t. Return to state. However, at time t. The position of both sliders 1 and 2 is a step width δ in the direction of arrow A compared to when . It's moving forward.

When the above cycle is repeated n times, both sliders 1 and 2
is nδ. resulting in a displacement of n, δ. By arbitrarily selecting , it is possible to obtain precise displacement in any range with any step width.

In the embodiment described above, expansion was used as the strain of the piezoelectric element 3, but contraction may also be used. Also, the base $ voltage is e□
;eI, and e2=0, so the step width is δ. is determined only by el, but it can also be set to e 2''t; O, in which case 1-e2 will determine the step width. If c2 is 0, then This is because the distortion will change between δ, which corresponds to elf02, and 62, and δ.=δ, -62. δ2
The term “kio” means that the piezoelectric element 3 is not always in a strain-free state, and means that zero point drift can be prevented. Also, if el>0 and e2 are set to 0, then δ,>0, δ2
0, the opposite strain to δ□ (if δ is elongated, then δ2
(reduced) δ2 can be used. Therefore, δ0
= δ knee δ2 = δ1 + 1 δ21. This is one step width δ. This shows that it is possible to double the amount by expanding and contracting.

Note that if a displacement is to occur in the opposite direction to the above operation, it is possible to reverse the polarity of the reference voltage e, but it is difficult to imagine that the characteristics of the piezoelectric element 3 will have the same sensitivity to expansion and contraction. Because it's not limited.

Not necessarily appropriate. For this purpose, the group X [pressure e
□t 62 may be left as is and the clamp timing may be reversed. That is, if the clamp is released on the slider 2 at time t□, the slider 2 will move in the opposite direction of the arrow A by a step width δ. If the slider 1 is displaced at time t and the clamp is released at time t, the slider 1 also moves in the opposite direction of arrow A.

(Effects) As described above, the present invention utilizes the strain of the piezoelectric element as a one-step displacement, and repeats it like an inchworm using the alternate clamping of the two sliders. The narrow operating range, which is a drawback, can be overcome, and arbitrary displacement can be obtained. Furthermore, step 11] can be made minute, which is a characteristic of piezoelectric elements, and can be made variable by adjusting the reference voltage.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a signal system according to an embodiment of the present invention, FIG. 2 is a time chart, FIG. 3A is a plan view of the embodiment, and FIG. 3B is a side view of the same. 1.2...Slider 3...Piezoelectric element 4...Pickup 5...Adder 6...Control circuit 9.10...Electromagnet 11.12...Guide patent applicant Koyo Seiko Co., Ltd. Company diagram 1

Claims (1)

[Claims] Two sliders that can move straight along guides arranged parallel to each other, a piezoelectric element that is fixed at both ends to both sliders and that relatively displaces both sliders by expansion and contraction, and measures the relative displacement between both sliders. a micrometer that clamps both sliders individually to the guide at a predetermined timing, a control circuit that switches and outputs two reference voltages, and uses the output of the micrometer as a feedback signal,
and a servo system that uses the reference voltage as a setting signal, the piezoelectric element is energized by the servo system, and the control circuit controls the clamping means at a predetermined timing synchronized with the switching timing of the reference voltage. A precision displacement generator characterized by: