JPH08110788A - Sound source for measuring instrument - Google Patents

Abstract

PURPOSE: To provide a small nondirectional sound source suitable for an anemometer. CONSTITUTION: Two needle-like electrode rods 24, 25 made of a conducting material are arranged so that their tips face each other at a prescribed gap, and a pulse-like high voltage is applied between two electrode rods 24, 25. The sound wave containing ultrasonic wave is uniformly emitted to the surrounding by an electric discharge between the electrode rods 24, 25.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sound source suitable for an anemometer for measuring wind direction, wind speed and the like and other measuring instruments using sound waves.

[0002]

2. Description of the Related Art Wind direction, wind speed, etc. (some of which can measure temperature at the same time) are utilized by utilizing the fact that the propagation speed of sound waves in the atmosphere changes depending on the direction and speed of the movement (wind) of the atmosphere. Anemometers for measuring are already known.
Conventionally, a small speaker has been exclusively used as the sound source of such anemometer. Speakers are magnetic or piezoelectric ceramics that convert an oscillating electrical signal into the motion of an object, thereby vibrating the air.

[0003]

In order to measure the wind direction and speed with high accuracy by utilizing the propagation velocity of sound waves, the sound source and the sound receiver should not affect the movement of the wind to be measured. There must be. Although it is possible to use a small microphone that has been developed in recent years for the sound receiver, as long as the above-mentioned principle is adopted, the sound source needs to have a certain amount of sound to generate a sound volume necessary for measurement. This requires a vibrating object, and there is a limit to miniaturization.

Further, the conventional sound source has a problem in directivity. For example, in the ultrasonic wind direction wind velocity temperature measuring device described in Japanese Patent Laid-Open No. 5-307087, the surroundings 4 around the sound source are used.
A sound receiver is arranged at each location, and the wind direction, wind speed, and temperature are measured based on the time taken for the sound emitted from the central sound source to reach the four sound receivers. Then
It is necessary to uniformly generate sound waves from the sound source to the sound receivers around it. In this case, conventionally, the direction of the emission intensity was made uniform by using an acoustic horn or the like, but this made the sound source larger and made it difficult to perform highly accurate measurement.

The present invention has been made to solve the above problems, and an object thereof is to provide a compact, non-directional device suitable for a measuring instrument using sound waves such as an anemometer. It is to provide a sound source.

[0006]

Means for Solving the Problems A sound source for a measuring instrument according to the present invention made to solve the above problems is a) made of a conductive material and provided with a predetermined gap so that its tips are opposed to each other. It is characterized by further comprising two needle-shaped electrode rods and b) a voltage application circuit for applying a pulsed high voltage between the two electrode rods.

[0007]

When a high voltage is applied from the voltage application circuit to both electrode rods, a discharge occurs across the gap between the tips of both electrode rods. This causes sound waves (including ultrasonic waves) to be generated, but the source of this sound wave is a very small portion, which is the gap between both electrodes, and its strength is 360 degrees around the straight line connecting the tips of both electrodes. Is uniform in the direction of.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An ultrasonic wind direction anemometer according to an embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1A, the measurement unit of the wind direction anemometer of this embodiment includes a sound source 20 that generates sound waves, and a sound source 20 that is arranged in four directions around the sound source 20.
The microphones 11 to 14 are provided. These are shown in Figure 1.
It is convenient to fix it on one base 10 as shown in (a) in terms of accuracy and handling, but they may be installed independently. The sound source 20 is provided on a stay (support) 21 made of a metal pipe, and the stay 21 is the base 10.
Keep it slightly longer to avoid wind turbulence.
Similarly, the microphones 11 to 14 are also provided on the support column and have the same height as the sound source 20. It is desirable to further extend the microphone column or the upper holding body 29 for the sound source 20 described later and to provide an umbrella for preventing a temperature rise due to rain or direct sunlight.

As shown in FIG. 1B, the sound source 20 comprises a lower discharge electrode rod 24 and an upper discharge electrode rod 25. The lower electrode rod 24 is fixed to the upper portion of the stay 21, and the upper electrode rod 2
5 is held by the upper holding body 29. Upper holder 29
Is connected and fixed to the stay 21 by a plurality of metal guards 22. The guard 22 also serves as a safety fence that prevents the human body from contacting the lower electrode rod 24 to which a high voltage is applied and the gap that is the discharge part, and dust (fallen leaves, etc.) enters the gap and is ignited by discharge. Role to prevent
It plays various roles, such as preventing insects from invading around the gap and preventing sound from leaking. As shown in FIG. 5 and FIG. 6 (these are other examples as described later, the stay 21 and the mounting portion of the lower electrode rod 24 have similar configurations), the pipe-shaped stay 21 An electric wire 28 is arranged inside via an insulating layer 27, and the electric wire 28 connects the lower electrode rod 24 and a high voltage side terminal of a pulse high voltage generating circuit 43 described later. Stay 2
In the mounting portion of the lower electrode rod 24 at the upper end of FIG.
As shown in FIG. 6, an insulating cap 23 is provided in order to prevent deterioration of insulation due to invasion of dust, rainwater, etc., and an O-ring 26 seals between the cap 23 and the inner wall of the stay 21. The upper electrode rod 25 includes an upper holder 29 and a guard 22.
And is grounded through the outer periphery of the stay 21. It is suitable that the outer diameter of the stay 21 is about 3 to 5 mm, and the outer diameter of each guard 22 is about 1 mm.

A high voltage applying circuit for applying a high voltage to the electrode rods 24 and 25 and an arithmetic circuit for calculating the wind speed, the wind direction and the like from the detection signals of the microphones 11 to 14 are provided under the base 10 or under the umbrella or the like. To be The configuration of these electric circuits is shown in FIG. The oscillation circuit 42 divides a crystal oscillator or a highly accurate reference signal obtained from the outside by
It outputs two reference clock signals 46 and 47. The reference clock signal 46 serves as a reference signal for generating a high voltage pulse, and also serves as a start signal for the timing circuits 38 to 41 to start measuring the propagation time of a sound wave. The reference clock signal 47 is the other reference clock signal 4
6, which is a pulse signal of a higher frequency than 6,
1 is a clock signal used as a reference for measuring time.

The pulse high voltage generating circuit 43 includes an oscillating circuit 4
A pulse-shaped high voltage is generated based on the reference clock signal 46 supplied from 2 and the two electrode rods 24, 25 of the sound source 20 are generated.
Apply between. Although various methods can be considered to generate a pulsed high voltage, generally, a low voltage pulse is boosted by using a single-winding or a double-winding transformer, or a recently developed piezoelectric transformer (electric signal To change the movement to electricity again) is more efficient. Both electrode rods 24,
The optimum value of the voltage applied to the gap between 25 varies depending on the volume of the required sound, but for example, when the gap between the electrodes is 1 mm, about 2 kV is suitable.

A sound wave including an ultrasonic wave is generated by the discharge between the electrode rods 24 and 25. The sound waves are both electrode rods 24, 25
It is uniformly emitted to the surroundings from the gap between them, but when propagating to the surroundings, its propagation speed varies depending on the movement (wind) of the atmosphere, which is the propagation medium. Therefore, the times detected by the four microphones 11 to 14 differ depending on the wind direction and the wind speed. Four microphones 11-14
The sound wave detection signal output from the band limiting amplifier 30 to 3
Amplified by 3 and binarized by the voltage comparators 34 to 37 using a predetermined reference voltage as a threshold. The thresholds given to the voltage comparators 34 to 37 are set to values such that only the discharge sound of the sound source 20 is extracted. The binarized signal is sent to the timing circuits 38 to 41. Each of the time counting circuits 38 to 41 starts counting the other reference clock signal 47 each time it receives a pulse of the reference clock signal 46 supplied from the oscillation circuit 42, and the four types of four voltage comparators 34 to 37 are supplied. The count value until the binarized signal of 1 arrives is stored in the prepared register. MP
The U circuit 44 reads the value of the register of each of the timing circuits 38 to 41, and based on these values, the time t ₁ from the time when the sound wave is emitted from the sound source 20 to the time when the sound wave reaches each of the microphones 11 to 14, Calculate t ₂ , t ₃ , and t ₄ .

The MPU circuit 44 calculates the wind direction, the wind speed and the temperature by the following procedure. In the following, for simplicity, it is assumed that the distance between the sound source 20 and each of the microphones 11 to 14 is L as shown in FIG. 3, but calculation is possible even if they are different from each other.

First, consider the microphones 11 and 13 facing each other across the sound source 20 as shown in FIG. Assuming that the sound velocity is c and the wind velocity in the direction from the microphone 13 to the microphone 11 (this direction is x) is v _x , t ₁ and t ₃ are respectively t ₁ = L / (c + v _x ) ... (1 ) T ₃ = L / (c−v _x ) ... (2) However, since the sound velocity c changes depending on the temperature T, the equations (1) and (2) are exactly t ₁ = L / (c ₀ + k · T + v _x ) ... (3) t ₃ = L / (c ₀ + k · T-v _x) ... it is expressed as (4). Here, c ₀ is the speed of sound at 0 ° C. (c ₀ =
331.5m / s), k is the rate of change in sound velocity per degree Celsius (k = 0.60)
7 (m / s) / deg). From the equations (3) and (4), the temperature T is calculated as T = (L / t ₁ + L / t ₃ −2 · c ₀ ) / (2 · k) (5).

By substituting the value of the temperature T into the equation (3), the wind speed v _{x +} from the sound source 20 to the microphone 11
Is v _{x +} = (L / t ₁ −L / t ₃ ) / 2 (6), and similarly, by substituting the value of the temperature T into the equation (4), the wind speed from the sound source 20 to the microphone 13 is v _x-
Is calculated as v _x− = − (L / t ₁ −L / t ₃ ) / 2 (7).

As can be seen from the equations (6) and (7),
Originally, v _{x +} and v _x- have only opposite signs, and their absolute values should be the same. However, when some abnormality occurs in this device, the absolute values of v _{x +} and v _x- are absolute. The calculated values may not match. Therefore, the MPU circuit 44 of the wind direction anemometer according to the present embodiment calculates the x-direction components v _{x +} , v _x- of the wind speed using both equations (6) and (7), and both v _{x +} , v By comparing the absolute values of _x- , it is determined whether or not any abnormality has occurred in this device. That is, when the absolute values of both are the same, v _{x +} = −v _x-
= V _x , the x-direction component of the wind speed is determined. When the two values do not match (v _{x +} ≠ −v _x− ), it is determined that the device is abnormal.

The other two microphone pairs 12, 14
Also for (this direction is y), the y-direction components v _{y +} and v _y- of the wind speed are calculated in the same manner as above. v _{y +} = (L / t _{y +} −L / t _y− ) / 2 (8) v _y− = − (L / t _{y +} −L / t _y− ) / 2 (9) The same applies to the y direction. Similarly, it is determined whether or not the device is abnormal, and when the absolute values of both values v _{y +} and v _y− are equal, v _{y +} = −v _y− = v _y is adopted as the component value in the y direction. The absolute values of the wind direction and the wind speed can be calculated from the component values v _x and v _{y in the} x direction and the y direction.

The MPU circuit 44 calculates the wind direction, the wind speed, and the temperature in the above-described procedure, and then outputs these data to the LCD panel, the CRD display or the like through the output circuit 45, or the data through the communication line. Send to the center etc. Also, by accumulating these data obtained over time, it is possible to periodically create a transition table or perform secondary data processing such as displaying average values, maximum / minimum values, etc. at the same time. Good.

The sound source according to the present invention is characterized in that it can uniformly emit sound waves around 360 degrees, but of course it is also possible to emit sound waves only in a limited part of the directions. For example, an L-shaped structure as shown in FIG. 3 can be used for emission in only one direction, and a T-shaped structure as shown in FIG. 4 as a sound source for emission in two directions. 5 and 6, the same symbols as those in FIG. 1 represent the same elements.

[0020]

The sound source according to the present invention is very small because it is composed of only two electrode rods. Also, since the narrow gap is the sounding portion, the sounding portion itself is small, and in addition, the sound is emitted uniformly in the surrounding 360 degrees, so that highly accurate measurement can be performed. Therefore, the sound source is suitable for various measuring instruments that measure distances and the like using sound waves, in addition to the wind direction and wind speed (temperature) meter.

[Brief description of drawings]

FIG. 1 is a perspective view (a) of a measurement unit of a wind direction anemometer and an enlarged perspective view (b) of a sound source according to an embodiment of the present invention.

FIG. 2 is an electric circuit diagram of the wind direction wind velocity thermometer of the embodiment.

FIG. 3 is an explanatory diagram showing a positional relationship between a sound source and a microphone.

FIG. 4 is an explanatory diagram showing a relationship between a sound wave propagation velocity in the x direction and a wind velocity.

FIG. 5 is a sectional view of an L-shaped sound source that is a second embodiment of the present invention.

FIG. 6 is a sectional view of a T-shaped sound source that is a third embodiment of the present invention.

[Explanation of symbols]

 10 ... Base 11, 12, 13, 14 ... Microphone 20 ... Sound source 21 ... Stay 22 ... Guard 23 ... Cap 24, 25 ... Discharge electrode rod 26 ... O-ring 27 ... Insulating layer 28 ... High voltage electric wire 29 ... Upper holding body 30 , 31, 32, 33 ... Band limiting amplifier 34, 35, 36, 37 ... Voltage comparator 38, 39, 40, 41 ... Timing circuit 42 ... Oscillation circuit 43 ... Pulse high voltage generation circuit 44 ... MPU circuit 45 ... Output circuit 46 ... Reference clock signal 47 ... Reference clock signal (high frequency)

Claims (1)

[Claims] 1. A) two needle-shaped electrode rods which are made of a conductive material and are provided with a predetermined gap so that their tips are opposed to each other; and b) a pulse is provided between the two electrode rods. And a voltage applying circuit for applying a high voltage of a circular shape, and a sound source for a measuring instrument using sound waves.