JPH0823488B2 - Displacement amount detection circuit and fluctuation amount control circuit using this circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a vehicle body posture control during running of a vehicle, a holography set, an electron microscope, a precision manufacturing apparatus for mounting an ultra-precision measuring apparatus such as a semiconductor manufacturing apparatus, and the like. A displacement amount detection circuit that accurately and accurately detects displacement amounts such as the level of the surface plate, and a variation amount control to prevent or reduce the transmission of micro vibrations from the floor surface and maintain or improve the accuracy of the equipment. The present invention relates to a novel control circuit in which the detection circuit is incorporated in a circuit.

(Prior Art and Problems Thereof) In a conventional displacement amount detection circuit, for example, a case where an encoder is used to detect a variation amount will be described. The moving scale of the encoder is attached, and the relative moving amount of the moving scale from the zero point of the reference scale is generated from the encoder as a pulse, and the moving amount is detected by counting the number of pulses. In this case, there is a problem that the detection accuracy and resolution of the movement amount are limited because they depend on the mechanical accuracy and mechanical structure of the pulse motor, and there is also a problem that the encoder itself becomes large if the accuracy is improved. There is also a problem in that the detection of the movement amount is limited by the capacity of the encoder.

Further, the conventional fluctuation amount control circuit merely detects the disturbance of the measured object transmitted from the floor surface and sends a signal corresponding to the disturbance to the drive circuit to perform the disturbance control. There was no countermeasure to deal with the level change due to the load fluctuation and the shift of the center of gravity.

(Object of the Invention) The present invention has been made in view of the drawbacks of the conventional example, and the object of the present invention is to be able to electrically count all displacement amounts of an object, and to achieve high detection accuracy and resolution. Not only can it be taken very high, but the volume of the device can also be made very compact, and by using this displacement amount detection circuit, not only disturbance control but also load fluctuation and center of gravity movement Is to provide a fluctuation amount control circuit that can also cope with this.

(Means for Solving Problems) In order to solve the problems of the related art, the present invention provides: a level sensor (11) for detecting a displacement amount δ of a device from a reference position; A reference voltage setter (13) that sets the reference position of as the reference voltage, and the displacement voltage from the level sensor (11) and the reference voltage from the reference voltage setter (13) are compared, and the difference is output. (14), a displacement pulse generator (2) for generating a constant pulse in accordance with an internal clock during the generation period of the displacement signal voltage output as a difference from the comparator (14), and the displacement pulse is added. A displacement amount detection circuit (A) is configured with an adder (3) that grasps the displacement amount by a digital amount.

In the second section, a vibration detection circuit (5) for detecting the vibration amount of the object to be measured by the vibration source (4) such as a floor surface or equipment as acceleration and a vibration detection circuit (5 ) Which outputs the fluctuation input signal from) as a fluctuation detection signal, a phase inverter (7) which reverses the phase of the fluctuation detection signal by 180 °, and an inversion signal which is output from the phase inverter (7). And from the adder (3) of the displacement amount detection circuit (A) of the first term, D
A level fluctuation adder (8) that adds the level displacement signal of the DUT that has been converted into an analog signal by the -A converter (15) and an addition fluctuation signal from the level fluctuation adder (8) Together with the drive circuit (9) which generates a drive signal, a fluctuation amount control circuit (B) is formed.

The technical means called; is adopted.

(Operation) The displacement amount detection circuit (A) will be briefly described. First,
A displacement amount sensing unit (1) including a level sensor (11), a reference voltage setting device (13) and a comparator (14) detects a displacement amount such as a level of an object to be measured such as a vehicle body or equipment, An analog displacement signal voltage is generated according to this displacement amount.

This analog displacement signal voltage is the displacement pulse generator (2)
, A constant pulse is generated from the displacement pulse generator (2) during the generation period of the displacement signal voltage according to the internal clock in the displacement pulse generator (2).

The displacement pulse is subsequently input to the adder (3), the input pulse number is counted by the adder (3), and then output as a displacement signal. As a result, the displacement amount is grasped as a digital amount.

Next, an outline of a fluctuation amount control circuit (B) using this displacement amount detection circuit (A) will be described. A vibration detection circuit (5) detects the amount of vibration of an object to be measured by a vibration source (4) such as a floor or equipment as acceleration.

An analog fluctuation detection signal is output from the arithmetic circuit (6) in accordance with the fluctuation input signal from the vibration detection circuit (5).

The phase of this fluctuation detection signal is inverted by 180 ° by the phase inverter (7).

The inverted signal output from the phase inverter (7) and the level displacement signal output from the adder (3) and converted into an analog signal by the DA converter (15) are added to the level fluctuation adder. In (8), not only the disturbance control but also the level correction are performed by adding.

The corrected addition fluctuation signal is input to the drive circuit (9),
The drive circuit (9) outputs a level-corrected disturbance control drive signal to the control mechanism.

(Examples) In describing the present invention, first, a displacement amount detection circuit (A) will be described, followed by a variation amount control circuit (B), and finally, a precision surface plate incorporating these. Description will be made by taking (C) as an example.

A. Example of displacement amount detection circuit (A) The displacement amount detection circuit (A) is, for example, a level sensor (11).
Displacement amount sensing unit composed of displacement amount amplifier (12) connected to a sensor for detecting the amount of displacement of the object to be measured from a reference position such as, a reference voltage setting device (13) and a comparator (14) (1), a displacement pulse generator (2), and a displacement amount detecting adder (3). Level sensor (11)
For example, when a load (D) is placed on a surface plate (C), the amount of sinking of the surface plate (C) is detected, and a detection signal voltage corresponding to the detected amount is generated. Here, the displacement amount is represented by δ. This detection signal voltage is amplified by the predetermined amount through the displacement amplifier (12) and input to the comparator (14). A reference voltage setting device (13) is also connected to the comparator (14), and the amplified detection signal voltage described above is compared with the reference voltage, and when it exceeds or falls below the reference, the comparator. It is output as a displacement signal voltage from (14) and input to the next displacement pulse generator (2). The displacement pulse generator (2) continues to generate and output a constant pulse in synchronization with the internal clock during the generation period of the displacement signal voltage. This displacement pulse is input to the next adder (3) and sequentially added, and the displacement amount is grasped as a digital amount. This displacement amount is output as a stepwise digital signal, input to the next D / A converter (15), and then output as a smooth displacement analog signal, and if necessary, the next level fluctuation adder (8) To enter.

Since the circuit configuration is as described above even when the displacement amount exceeds the capacity of the level sensor (11), the number of pulses is counted as long as the displacement amount detection potential deviates from the reference potential. After that, the moving side returns to the home position, the displacement amount becomes zero, and then the counting of the pulse number stops, and even if the level sensor (11) is overscaled, the zero point can be accurately returned. is there.

B. Example of fluctuation amount control circuit (B) The fluctuation amount control circuit (B) includes a vibration detection circuit (a low-pass filter (17) connected to a vibration sensor (16) such as an acceleration sensor ( 5), an arithmetic circuit (6), a phase inverter (7), a level fluctuation component adder (8) and a drive circuit (9).

First, the vibration transmitted from the vibration source (4) such as the floor surface or equipment to the object to be measured is detected by the vibration sensor (16) as the corresponding vibration signal voltage. High-frequency components are superposed, and if necessary, high-frequency components are passed through the next low-pass filter (17) and output as a vibration signal voltage of only relatively low-frequency components. Of course, if the control mechanism described later can sufficiently respond to the high frequency component, it is not necessary to pass the high frequency component. The vibration signal voltage thus passed is next inputted as a vibration signal to the arithmetic circuit (6) and outputted as a fluctuation detection signal. This fluctuation detection signal is then input to the phase inverter (7), and an inverted signal with the phase inverted by 180 ° is output and input to the next displacement amount adder (8).

The inverted signal output from the phase inverter (7) and the level displacement signal output from the adder (3) of the displacement amount detection circuit (A) are input to the level fluctuation adder (8). Is added, subtracted, output, and input to the next drive unit. The drive section outputs a drive signal in accordance with the added variation signal from the level variation adder (8), and the added variation signal is used to control the attitude of the control mechanism and to suppress the vibration.

This point will be described in more detail by taking as an example the case of being incorporated in the precision surface plate (C). The precision surface plate (C) is supported by an air spring (21) equipped with a pressure vessel (20).
The pressure control of 1) is performed by a control valve (18) such as a servo valve or a proportional control valve and a regulator (19).
The control circuit controls opening / closing of the control valve (18) to control the pressure of the air spring (21).

Now, when a load (D) is applied to the precision surface plate (C), the precision surface plate (C) sinks corresponding to the load (D). This sink amount δ
Is immediately detected by the level sensor (11), is input to the drive circuit (9) through the above-mentioned path, and the excitation voltage or current of the control valve (18) is adjusted to adjust the pressure container (of the air spring (21) ( The necessary amount of compressed air is supplied to 20) to inflate the air spring (21) and drive the precision surface plate (C) to return to the home position. When the precision surface plate (C) is completely restored, the comparator (14) compares the reference voltage setter (13) with the level sensor output, and the displacement amount δ is zero, so the displacement signal voltage is also zero. . At this time, the load (D) is added by the adder (3).
Since the number of pulses generated by is counted, the exciting current matching the load (D) continues to flow from the drive circuit (9) to the control valve (18) (or the exciting voltage is applied), The pressure vessel (20) of the air spring (21) is continuously supplied with compressed air to keep lifting the load (D) to the home position.

When the precision surface plate (C) is lifted beyond the home position, the level sensor (11) generates a displacement signal voltage opposite to the above, and the precision surface plate (C) is lowered to the home position. Operates to return.

On the other hand, on the side of the fluctuation control circuit (B), the phase inverter (7)
Since an inversion signal whose phase is inverted by 180 ° is output at, the vibration generated from the vibration source (4) is canceled and the precision surface plate (C) becomes almost stationary.

In this way, the level is quickly returned and the vibration is suppressed, and the posture control and vibration isolation of the device are performed.

(Effect) The displacement amount detection circuit according to the first aspect of the present invention includes a displacement amount sensing unit that detects a displacement amount of a device and generates a displacement signal voltage, and a displacement signal voltage that is constant during a generation period of the displacement signal voltage according to an internal clock. Since it is composed of a displacement pulse generator that generates a pulse and a displacement pulse adder that grasps the displacement amount by a digital amount, unlike the conventional encoder system, the detection accuracy and resolution of the movement amount Is electrically determined, which not only provides extremely high accuracy, but also has excellent responsiveness, and has the advantage that no scale over occurs regardless of the amount of displacement and the capacity is compact. .

The fluctuation amount control circuit according to the second aspect of the present invention is a vibration detection circuit that detects a vibration amount of an object to be measured due to a vibration source such as a floor surface or equipment, and a fluctuation input signal from the vibration detection circuit. An arithmetic circuit that outputs a detection signal, a phase inverter that inverts the phase of the fluctuation detection signal by 180 °, an inversion signal output from the phase inverter, and an output signal from the adder of the displacement amount detection circuit of the first term. It is composed of a level variation adder for adding the level displacement signal of the object to be measured and a drive circuit for generating a drive signal in accordance with the addition variation signal from the level variation adder. Not only can the vibration of the vibration source be canceled by this, but the level can be quickly restored as described above, so a practical fluctuation control circuit that can be applied to an actual machine could be made.

[Brief description of drawings]

FIG. 1 ... Circuit diagram of an embodiment of the present invention FIG. 2 ... Schematic configuration diagram of a precision surface plate to which the circuit of the present invention is applied FIG. 3 ... Graph and control showing changes in current flowing through a control valve of the present invention Drawing showing correspondence with time waveform (A) …… Displacement amount detection circuit, (B) …… Variation amount control circuit (C) …… Precision surface plate, (D) …… Load (1) …… Displacement Quantity sensing unit (2) …… Displacement pulse generator (3) …… Adder, (4) …… Vibration source (5) …… Vibration detection circuit, (6) …… Computation circuit (7) …… Phase inversion Unit, (8) …… Level fluctuation adder (9) …… Drive circuit (11) …… Level sensor, (12) …… Displacement amount amplifier (13) …… Reference voltage setter, (14) …… Comparator (15) …… D / A converter, (16) …… Vibration sensor (17) …… Low pass filter, (18) …… Control valve (19) …… Regulator, (20) …… Pressure Vessel (21) ... the air spring

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masashi Yasuda 5-chome, Minamitsukaguchi-cho, Amagasaki City, Hyogo Prefecture, 17-43 Patent Equipment Co., Ltd. (56) References JP-A-60-52772 (JP, A) JP-A-SHO 60-222309 (JP, A)

Claims (2)

[Claims] 1. A level sensor for detecting a displacement amount of a device from a reference position, a reference voltage setting device for setting the device reference position as a reference voltage, and a displacement voltage from the level sensor and a reference from a reference voltage setting device. A comparator that compares the voltage and outputs the difference, a displacement pulse generator that generates a constant pulse in accordance with the internal clock during the generation period of the displacement signal voltage output as the difference from the comparator, and the displacement pulse And a displacement amount detection circuit configured to add the displacement amount and digitally grasp the displacement amount. 2. A vibration detection circuit for detecting, as acceleration, a vibration amount of an object to be measured by a vibration source such as a floor surface or equipment, an arithmetic circuit for outputting a fluctuation input signal from the vibration detection circuit as a fluctuation detection signal, and a fluctuation. The phase inverter for inverting the phase of the detection signal by 180 °, the inversion signal output from the phase inverter, and the first
From the level fluctuation amount adder for adding the level displacement signal of the DUT output from the adder of the displacement amount detection circuit and converted into the analog signal by the DA converter, and from the level fluctuation amount adder. A variation amount control circuit using a displacement amount detection circuit, the variation amount control circuit being configured by a drive circuit that generates a drive signal in accordance with the addition variation signal of.