JPH10122844A - Ultrasonic measuring device and its temperature correction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure the displacement distance of a detection object that does not include an error even if a sound velocity changes by using the time difference of electrical signals equivalent to a reflection wave from a reflection plate being spaced from the detection object by a known distance. SOLUTION: The configuration of a device is achieved by adding only a reflection plate 6 and a memory 7 to a device without any temperature correction function. An ultrasonic wave U0 that is discharged from an ultrasonic sensor 2 is propagated in air and is partially reflected by a reflection plate 6, is received by the ultrasonic sensor 2 after being reflected on water surface, and is subjected to operation processing. Then, a measurement is made at a certain temperature and the measured value is stored in the memory 7. (The measurement is called memory measurement to distinguish itself from an actual measurement. And, a measurement may be made only once before the actual measurement if a detection object is the same but may be made in the case of an actual measurement).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic measuring apparatus for measuring the displacement of a detection object and a change in the water level of a water surface using airborne ultrasonic waves, and a method of correcting the temperature thereof.

[0002]

2. Description of the Related Art FIG. 4 is a block diagram schematically showing the configuration of a conventional ultrasonic measuring apparatus of this type. In the drawing, reference numeral 1 denotes a pulse generator, 2 denotes an ultrasonic sensor (transmitter / receiver), and 3 denotes A signal processing circuit, 4 is a display, 5 is a water surface, 10 is a temperature sensor, and 11 is a temperature correction circuit. As is well known, this type of ultrasonic measuring device uses an ultrasonic sensor 2 and a water surface 5 based on a burst pulse signal from a pulse generator 1.
, And the reflected wave reflected by the water surface 5 is received again by the ultrasonic sensor 2, converted into an electric signal, and input to the signal processing circuit 3. The time t from when the ultrasonic wave is emitted from the ultrasonic sensor 2 to when the reflected wave is received is the time required for the ultrasonic wave to reciprocate the distance L between the ultrasonic sensor 2 and the water surface 5, and v, L = (1/2) ·
It is well known that the distance L is obtained by t × v (1).

However, the speed of sound depends on the temperature of the medium through which the sound propagates. For example, in air, v = 331 + 0.6T m / sec (2) (T
Since the temperature changes with temperature), a means for correcting an error caused by a temperature change is required in the measurement of a delicate water level change or the like. Therefore, the temperature sensor 10 and the temperature correction circuit 1
1 is provided to obtain an accurate sound speed at the time of measurement, and the signal processing circuit 3 obtains an accurate distance L from the above formula (1) based on the sound speed. However, in such a temperature correction method, it is necessary to provide a temperature sensor.

FIG. 5 is a diagram showing the vicinity of an ultrasonic sensor of a conventional ultrasonic measuring device capable of temperature correction without using a temperature sensor. Metal rods 201 whose distances L1, L2 are known in advance,
A tube 20 is provided, which crawls 202 horizontally, and a part of the emitted ultrasonic wave U ₀ is first reflected by the metal bar 201, then reflected by the metal bar 202, and finally reflected by the water surface 5. ing.

[0005] As shown in FIG.
0 attached when transmitting and receiving ultrasonic waves from the ultrasonic sensor 2, and the electric signal S ₀ corresponding to the firing wave U _0, the metal rod 20
Electrical signals S ₁ , S ₂ corresponding to the reflected waves at 1,202
When, can be received and an electric signal S _W corresponding to reflected waves U _w from the water surface 5. The signal t ₁ is the time between the S ₀ to S _1, S time t ₂ up _2, S time until _W is t _W
If it was in, the change in temperature only sound speed is changed, L = the {(L2-L1) / ( t 2 -t 1)} × t W ··· (3), contains an error due to a temperature change You can measure the distance to the surface of the water.

[0006]

In the conventional ultrasonic measuring apparatus and the temperature correcting method as described above, the first method requires a temperature sensor, which increases the cost. Also the second
In the above method, it is necessary to attach a tube provided with at least two known metal rods at a known distance to the transmitting / receiving port of the ultrasonic sensor, which complicates the configuration and handling and also increases the cost. There were problems such as becoming.

The present invention has been made in order to solve such a problem, and an object of the present invention is to provide an ultrasonic measuring apparatus having a very simple and inexpensive configuration and a method of correcting the temperature thereof.

[0008]

A temperature correction method for an ultrasonic measuring device according to the present invention transmits and receives an ultrasonic wave from an ultrasonic transducer to a detection object, and displaces the detection object (Lx).
In a temperature correction method of an ultrasonic measuring device that measures without including an error due to a change in sound speed due to a temperature change, an ultrasonic wave is transmitted and received to the detection object before actual measurement. the electrical signal S _R corresponding to the reflected wave from the reflecting plate placed from the ultrasonic transducer to the known distance L _R, an electric signal corresponding to the reflected wave from the detection object between vessel and said detected object with S _W1, electrical signal S corresponding to the firing wave
The respective time differences t _R and t _W1 from ₀ are stored and actually measured, and the electric signal S _R ′ corresponding to the reflected wave from the reflector and the reflected signal from the detection object are equivalent. the electric signal S _W2, the electric signal S corresponding to the firing wave
_If the respective time differences from ₀ are t _R ′ and t _W2 , then Lx = {t _W2 − (t _W1 / t _R ) × t _R ′} × (L _R / t
_R ′) is used to determine the displacement distance (Lx) of the detection object.

[0009] As the device configuration, the ultrasound before the reflecting plate provided at a known distance L _R from the ultrasonic transducer between the detected object and the ultrasonic transducer, the actual measurement Ultrasonic waves are transmitted and received from the transducer, and an electric signal S _R corresponding to a reflected wave from the reflection plate and an electric signal SW ₁ corresponding to a reflected wave from the detection object correspond to emission waves. A memory for storing the respective time differences t _R and t _W1 from the electric signal S _0, an electric signal S _R ′ corresponding to a reflected wave from the reflection plate, which is actually measured, and a signal from the detected object. If the electrical signal S _W2 corresponding to the reflected wave, each of the time difference between the electric signals S ₀ corresponding to the firing wave was t _R 'and _{t W2, Lx = {t W2} - (t W1 / t R ) × t _R ｝ × (L _R / t
_R ′) and a calculation circuit for calculating a displacement distance (Lx) of the detection object. That is, the displacement distance of the detection object which does not include an error even if the sound speed changes due to the temperature can be measured by one reflector at a known distance L _R , a memory, and a simple arithmetic expression.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an apparatus configuration of an ultrasonic measuring apparatus according to the present invention. In the figure, 1 is a pulse generator, 2 is an ultrasonic sensor, 3 is a signal processing circuit, 4 is a display, 5 water, 6 reflector for reflecting a portion of the ultrasound U ₀ emitted provided from the ultrasonic sensor 2 a known distance L _R, 7 is a memory. Note that this device configuration can be realized with a simple configuration in which the reflection plate 6 and the memory 7 are added to the ultrasonic measurement device having no temperature correction function.

Next, the operation will be described. The ultrasonic wave U ₀ emitted from the ultrasonic sensor (transmitter / receiver) 2 propagates in the air, and a part of the ultrasonic wave U ₀ is reflected by the reflection plate 6, then reflected on the water surface and received by the ultrasonic sensor 2. Is converted into an electric signal, and is processed by the signal processing circuit 3. In the present embodiment, measurement is performed at a certain temperature, and the measured value is stored in the memory 7 (this measurement is also referred to as memory measurement in order to distinguish this measurement from actual measurement. If they are the same, it is only necessary to measure once before the actual measurement, but it is also possible to measure at the time of the actual measurement.)

[0012] As shown in FIG. 2, if at the time the memory measurement at the position of the water surface 5-1, as shown in FIG. 3 (A), and the electric signal S ₀ corresponding to the firing wave U _0, reflector The time difference from the electric signal S _R corresponding to the reflected wave reflected at 6 is t
_R, if the time difference between the electric signals S _W1 corresponding to the reflected wave U _W1 reflected by the surface of the water 5-1 was t _W1, allowed to store the time difference t _R and t _W1 in the memory 7.

Next, at the time of actual measurement, the temperature and the water level change from the time of the above-mentioned memory measurement. First, considering the change due to the temperature, for example, when the temperature drops and the sound speed becomes slower than at the time of the memory measurement, FIG. As shown in FIG. 3 (B), both the time difference t _R and the time difference t _W1 extend and change to the time differences t _R ′ and t _W1 ′. Since the ratios of these changes are equal, (t _R / t _R ′) = ( t _W1 / t _W1 ') (4) The relational expression of t _W1 ' = (t _W1 / t _R ) × t _R '(5) holds.

Next, in the change of the water surface, that is, in the actual measurement, at this temperature, the water surface changes from (5-1) to (5-2) in FIG.
As shown in FIG. 3, if the distance Lx is lowered,
As shown in (C), the reflected wave U _W2 reflected on the water surface 5-2
Since the time difference t _{W2 from} the electric signal _{SW 2} corresponding to the above is delayed by the time t _X corresponding to the distance Lx from the time difference t _W1 ′, t _W2 = t _W1 ′ + t _X (6) t _X = t _W2 -t _W1 '··· (7) is established. By the expression (7) and equation _{(5), t X = t} W2 - (t W1 / t R) × t R '··· (8) is satisfied.

The distance L _X is Lx = t _X × (L _R /
'Since) (9) is _{satisfied, Lx = {t W2 - (} t W1 / t R) × t R' t R _{a} × (L R / t R} ') ··· (10) . L _{R in} equation (10) is a known distance,
t _R and t _W1 are numerical values stored in the memory, and t _R 'and t _W2 are numerical values obtained by actual measurement. Even if the sound speed changes due to a temperature change, the water level change Lx is not affected by this change. Measurement becomes possible. In the above embodiment, the case where the change in the water level is measured has been described. However, it is needless to say that the present invention can be used for measuring the change in the position of the detected object in the air.

[0016]

As described above, the ultrasonic measuring apparatus and the temperature correcting method of the present invention have an effect that the ultrasonic measurement can be performed with a very simple and inexpensive configuration and without error caused by a temperature change.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of a device configuration of an ultrasonic measuring device of the present invention.

FIG. 2 is a diagram for explaining a measuring method in the ultrasonic measuring device of the present invention.

FIG. 3 is a timing chart for explaining a measuring method in the ultrasonic measuring device of the present invention.

FIG. 4 is a block diagram showing an example of a device configuration of a conventional ultrasonic measuring device of this type.

FIG. 5 is a block diagram showing another example of the device configuration of this type of conventional ultrasonic measurement device.

FIG. 6 is a timing chart for explaining a measuring method of the apparatus shown in FIG. 5;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pulse generator 2 Ultrasonic sensor (transmitter / receiver) 3 Signal processing circuit 4 Display 5 5-1 and 5-2 Water surface 6 Reflector 7 Memory

Claims (2)

[Claims] 1. An ultrasonic measurement system for transmitting and receiving an ultrasonic wave from an ultrasonic transducer to a detection object and measuring a displacement distance (Lx) of the detection object without including an error due to a change in sound speed due to a temperature change. In the temperature correction method of the apparatus, transmitting and receiving ultrasonic waves to the detection object before actual measurement,
And an electric signal S _R corresponding to the reflected wave from the reflecting plate placed from the ultrasonic transducer to the known distance L _R between the detected object and the ultrasonic transducer, the reflected wave from the detection object The respective time differences t _R and t _W1 from the electric signal S ₀ corresponding to the emitted wave with _respect to the electric signal S _W1 corresponding to are stored, and actually measured, and correspond to the reflected wave from the reflector. electric signal S _R that case 'and, between the electric signals S _W2 corresponding to the reflected wave from the detection object, each of the time difference between the electric signals S ₀ corresponding to the firing wave t _R' was and t _{W2 , Lx = {t W2 - (} t W1 / t R) × t R '} × (L R / t
_R ′), a temperature correction method of the ultrasonic measuring device for obtaining the displacement distance (Lx) of the detection object. 2. Ultrasonic measurement for transmitting and receiving an ultrasonic wave from an ultrasonic transducer to a detection object and measuring a displacement distance (Lx) of the detection object without including an error due to a change in sound speed due to a temperature change. An apparatus, comprising: a reflector provided at a known distance L _R from the ultrasonic transducer between the ultrasonic transducer and the detection object; and an ultrasonic transducer from the ultrasonic transducer before actual measurement. Transmits and receives a sound wave, and generates an electric signal S corresponding to a reflected wave from the reflector.
_R and an electric signal S corresponding to a reflected wave from the detection object.
Of _W1, and the respective memory for storing the time difference t _R and t _W1 from the electric signal S ₀ corresponding to the firing wave, performs the actual measurement, the electric signal S corresponding to the reflected wave from the reflector _When the time differences between _R ′ and the electric signal S _W2 corresponding to the reflected wave from the detection object from the electric signal S ₀ corresponding to the emission wave are t _R ′ and t _W2 , Lx = ｛ t _W2 − (t _W1 / t _R ) × t _R ′｝ × (L _R / t
_R ′), an arithmetic circuit for calculating a displacement distance (Lx) of the detection object.