JPH0460428A - Mechanism for driving relative flat board - Google Patents

Abstract

PURPOSE:To enable high speed sweeping with a compact apparatus and also improve control voltage, linearity in a moving distance and temperature characteristics by providing a plurality of strain generating units for coupling two holding means which hold relative flat boards on a fixed side and a moving side. CONSTITUTION:When a distance between two relative flat boards 5, 6 is to be set to a target value, first a resistance value of a variable resistor VR3 is varied and set to set voltage corresponding to the target value. The set voltage is amplified 22 and output to adders 26 of control circuits of three strain generating units 15 to be input to one of input terminals of comparators 27. Strain signals from respective strain gages 10 and temperature signals are input to the other input terminal of the comparators 27 at this time. Then a difference between potentials in both terminals is amplified 28 and driving voltage is applied to an electrostrictive element 8. At this time the element 8 stretches in proportion to the approximate voltage so that each strain generating unit 15 is stretched resulting in occurrence of a strain proportional to the stretch. The strain is detected by the strain gape 10 and fed back to the main control circuit. Thus the two relative flat boards 5, 6 can be correctly moved to the target value while their parallelism maintained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention is applicable to devices with a moving distance of several μm, such as a Fabry-Bello interferometer.
The present invention relates to an optical device of m, in particular to a driving mechanism of a relative plane plate.

(Prior art) Conventionally, this type of drive 8! Horizontally, ■ those that change the refractive index and change the optical path length by changing the air pressure between the relative plane plates, ■ the ones that move the parallel plane purely mechanically, ■ the ones that tilt the relative plane plates themselves, and ■ the electrostrictive ones. Electrical parallel movement using elements or magnetostrictive elements, etc. are used. In particular, the method (2) of electrically moving parallel movement is a) capable of high-speed sweeping, b) miniaturization is possible, and has a small space length. It has the following characteristics: (1) relatively high stability; and (4) parallelism adjustment is relatively easy. Closed control, which feeds back the output signal of the controller, is often used.

(Problems to be Solved by the Invention) Among the conventional drive mechanisms described above, the method of changing the refractive index by changing the air pressure between relative plane plates requires a large-scale gas pressure regulating device, and it is difficult to change the air pressure at high speed. Because it is difficult,
High-speed sweeping is difficult, and the method of tilting the relative plane plate itself requires advanced techniques for driving and supporting methods, and high-speed sweeping is difficult because the rigidity and natural frequency are reduced.

Furthermore, the method of purely mechanical translation has drawbacks such as the overall size of the device, relatively low precision and difficult adjustment, and the inability to provide optical position feedback or high-speed sweeping. , methods of driving using electrostrictive elements, etc. have been frequently used. However, even with this method, the relationship between the applied voltage and displacement of the electrostrictive element is not linear, and even if a constant voltage is applied, the displacement may fluctuate due to the creep phenomenon, and the temperature coefficient of the element itself is large. there were. In addition, the method of feeding back the output signal of a capacitive position sensor has the disadvantage that the linearity and temperature coefficient of the sensor itself are low, and the capacitance is also small, especially when the distance between relative plane plates is large. It got bigger.

The present invention was devised to eliminate the above-mentioned drawbacks of the conventional technology, and is compact and capable of high-speed sweeping, and has high linearity and temperature characteristics of control voltage and moving distance, and has high precision. It is an object of the present invention to provide a drive am for a relative plane plate.

(Means for Solving the Problems) In order to solve the above problems, the present invention provides a drive 8! that fixes one of two relative plane plates and moves the other relative plane plate in the normal direction. A holding means for holding the fixed side relative flat plate, a holding means for holding the movable side relative flat plate, a plurality of strain generating parts connecting the two holding means, and a a plurality of electro-strain converting elements that expand and contract in a direction that changes the distance of the holding means; a plurality of strain gauges that are attached to the strain generating section to detect strain in the plurality of strain generating sections; and the two relative plane plates. setting means for providing a setting signal for setting the distance between the two to a target value;
A feedback circuit is provided for feeding back the output signal of the strain gauge to the control signal of the electro-strain conversion element.

(Function) When setting the distance between two relative plane plates to a target value by the drive mechanism of the present invention, a signal is applied to a plurality of electro-strain conversion elements by the setting means, and a direction in which the distance between the two holding means is changed is applied. Attempts to expand and contract.

This expansion and contraction is absorbed by the strain generating section, and distortion occurs in the strain generating section. This strain is detected by multiple strain gauges, and the output signal is fed back to the applied signal of each electro-strain conversion element by a feedback circuit, so that the two relative plane plates maintain parallelism and accurately reach the target value. will be moved.

(Embodiment) An embodiment of the relative plane plate drive mechanism of the present invention will be described with reference to FIGS. 1 to 3. FIG. 1 is a longitudinal cross-sectional view of the drive mechanism main body of the relative plane plate, and FIG. 2 is a cross-sectional view taken along the line A-A.

In FIG. 1, the fixed relative plane plate 5 and the movable relative plane plate 6 are fixed by an appropriate method such as adhesive so as not to cause optical distortion in the holder 4 and the holder 2, respectively.
Holder 4 and holder 2 each have a screw 12 and a screw Li.
2 is fixed to the body 1. The body 1 has a shape in which two coaxial circular tubes are connected by three thin-walled tile-shaped strain generating parts 15, and the upper surface of the lower circular tube has two equally shaped plates as shown in Fig. 2. A fan-shaped spacer 7 is glued. A square hole is bored in the center of the fan-shaped spacer 7, into which the electrostrictive element 8 is fitted.

A spacer 9, which is slightly larger than the cross section of the electrostrictive element 8, is bonded to the other end of the electrostrictive cable 8, and pressurization is applied to the electrostrictive element 8 in the axial direction by a setting screw 11. A strain gauge 10 and a temperature sensor 14 such as a thermocouple are attached to the outer surface of the strain generating section 15. Further, a cover 3 is provided to protect the strain generating section 15.

Further, FIG. 3 shows an outline of a control circuit mainly related to one distortion generating section 15, and the part surrounded by a broken line is a setting circuit 4.
To explain the structure and operation of the circuit, the fixed resistors R1, R2°R3 form a balanced bridge together with the strain gauge 10, and the resistance from the strain gauge 10 whose zero point is adjusted by the variable resistor VRI is explained. The output signal is amplified by amplifier 3o. Further, the output signal from the temperature sensor 14 is amplified by the amplifier 21. In addition, amplifier 2
The amplification factor of 1 is adjusted by variable resistor VR2.

In order to simultaneously set the displacements of the three distortion generating sections 15 by the variable resistor VR3, the set voltage is sent to the other two distortion generating sections 15 via the amplifier 22.

In order to adjust the displacement of each distortion generating section by the variable resistors VR4, VR5, VR6, the set voltage is applied to the amplifier 23.
24 and 25 to the control circuits of the first, second, and third distortion generating sections 15, respectively.

When the selector switch S is in position a, the adder 26 receives the set voltage from the variable resistor VR3 that simultaneously sets the displacement of the three distortion generating sections, and the set voltage from the variable resistor VR4 that sets only the displacement of the first distortion generating section. Add the set voltage of The comparator 27 compares the displacement signal outputted from the amplifier 20 on which the output signal from the temperature sensor 14 is superimposed, and the setting signal outputted from the adder 26, and outputs the difference output to the amplifier 28. The amplifier 28 amplifies the difference output from the comparator 27 to a voltage sufficient to drive the electrostrictive element 8.
to drive. In addition, this circuit has a photodiode 29 and a transmitter 30 that detect the intensity of the luminous flux after passing through the main driver ellipse, and by setting the changeover switch S to the position C,
A comparator 27 uses the output from this optical sensor as a setting signal.
By setting the switch S to position b, a high-speed sweep can be performed by superimposing an alternating signal from the transmitter 30 on the manual setting signal.

Next, to explain the operation of the drive mechanism of the present invention, when setting the distance between two relative plane plates to a certain target value, first change the resistance value of the variable resistor VR3, and then apply the set voltage corresponding to the target value. Set to . This set voltage is amplified by the amplifier 22, and the adder 26 of the control circuit of the three distortion generating sections 15
and is input to one of the input terminals of the comparator 27 of each distortion generating section. At this time, the strain signal from each strain gauge 10 and the temperature signal from the temperature sensor 14 are input to the other input terminal of the comparator 27. Thereby, the potential difference between both terminals is amplified by the drive amplifier 28, and a drive voltage is applied to the electrostrictive element 8. At this time, the electrostrictive element 8 generates a force in an extending direction substantially in proportion to the voltage. Each strain generating section 15 is stretched by this force, and a strain proportional to the stretch is generated. This strain is detected by strain gauges 10 attached to each strain generating section 15 and fed back to the main control circuit. In this way, a voltage is applied to the electrostrictive element 8 until the potential difference between the input terminals of the comparator 27 becomes zero, and the moving side relative plane plate moves in the normal direction.

However, since the characteristics of the electrostrictive element 8, circuit element, strain gauge 10, and temperature sensor 14 of each strain generating section 15 are different, the two relative plane plates do not necessarily move while remaining parallel. While detecting the optical path after passing through the etalon drive v1 ellipse, the resistance values of the variable resistors VR4, VR5, and VR6 are changed, and the set voltage input to the adder 26 of each distortion generating section 15 is changed. As a result, each strain generating section 15 can be moved independently, and the two relative plane plates can be kept parallel.

Note that the setting circuit 40 is not limited to the circuit shown in FIG. 3, but can also be used to maintain parallelism between the relative plane plates when signals from the photodiode 29 and the oscillator 31 are inputted, as in the embodiment shown in FIG. , the voltage regulators VR7 and VH2 may be provided individually, or the voltage regulators of each strain generator may be connected to the signal line of the strain gauge as in the embodiment shown in FIG. Combinations of this embodiment and other embodiments are also possible. Further, in the above embodiment, the circuit was controlled using an analog element, but it may also be controlled digitally using a CPU or the like.
Although we have explained the case where an electrostrictive element is used as a strain conversion element,
A magnetostrictive element can also be used.

In addition, in this example, since the temperature signal of the support member of the relative plane plate is fed back, the temperature characteristics are further improved.
By using the signal from the optical sensor as the setting signal,
Furthermore, highly accurate position control is possible.

Furthermore, in the above embodiment, when a voltage is applied to the electrostrictive element, the electrostrictive element expands, and the gap between the two relative plane plates becomes large.However, conversely, when a voltage is applied to the electrostrictive element, To,
A structure may be adopted in which the distance between the two relative plane plates is reduced.

(Effects of the Invention) The etalon drive mechanism of the present invention provides the following effects.

b) Sensitivity, linearity, and temperature characteristics are improved because the displacement of the relative plane plate is detected using a strain gauge.

Since the electro-strain conversion element is fixed and the strain generated in the strain generation part is detected, adverse effects such as applied voltage-strain nonlinearity, cleave phenomenon, and poor temperature coefficient are eliminated.

c) Since multiple electro-strain conversion elements can be controlled independently,
Parallelism can be easily adjusted.

2) The structure is simplified and miniaturization is possible.

e) Since the driving source is an electro-strictive conversion element, high-speed sweeping is possible.

[Brief explanation of the drawing]

1 to 3 relate to an embodiment of the etalon drive mechanism of the present invention, in which FIG. 1 is a longitudinal sectional view, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 3 is a control Schematic diagram of the circuit, 4th
5 and 5 are diagrams showing other setting circuits within the control circuit of FIG. 3. 2.4: Holder 5: Fixed side relative flat plate 6 Moving side relative flat plate 8: Electrostrictive element 10: Strain gauge 15: Strain generating section VR3, VR4, VR5, VR6: Variable resistor 29: Photodiode Patent applicant Shimadzu Corporation -1fr, -4-! i Agent Patent Attorney Hajiko Takeishi - Iya? i Name 1ji Bow H-rl Hanging 1st Day Figure No. 5121

Claims (1)

[Claims] In a drive mechanism that fixes two relative plane plates and moves the other relative plane plate in the normal direction, holding means holds the fixed side relative plane plate and holding means holds the movable side relative plane plate. , a plurality of strain generating parts connecting the two holding means, and a plurality of electro-strain conversion elements arranged between the two holding means and expanding and contracting in a direction that changes the distance between the two holding means when a signal is applied. a plurality of strain gauges attached to the plurality of strain generating parts to detect strain in the strain generating parts; a setting means for setting a distance between the two relative plane plates to a target value; A driving mechanism for a relative flat plate, comprising a feedback circuit that feeds back an output signal to a control signal for the electro-strain conversion element.