JPS63122983A - Ultrasonic range finder - Google Patents

Abstract

PURPOSE:To enable the measuring of a correct distance with a head small in the directional angle without being affected by environments such as temperature, by arranging an ultrasonic wave transmitting/receiving head and an ultrasonic wave receiving head longitudinally back and forth in the same direction of directivity. CONSTITUTION:An ultrasonic wave receiving head 2 has the same direction of directivity as an ultrasonic receiving head 1 and is set at a position behind the head 1 shifted by a specified interval (d). A measuring section 3 outputs an ultrasonic wave signal to the head 1 while signals received by both the heads 1 and 2 are inputted to compute a distance to be measured. The heads 2 and 1 are integrated by arranging the head 1 above the head 2 or the head 1 ahead of 2. Thus, an ultrasonic wave transmitted from the head 1 is received by the head 1 while done by the head 2 delayed in time thereby enabling the computing of a distance to an object to be measured from required time for the heads 1 and 2 and a specified distance between both the heads.

Description

[Detailed Description of the Invention] (Field of Application of the Invention) This invention relates to a distance meter using ultrasonic waves.
In particular, it relates to something that can accurately measure distance without being affected by the environment such as temperature.

(Prior Art) Conventionally, a rangefinder using ultrasonic waves is known, and the ultrasonic rangefinder has an ultrasonic transmitting/receiving head (hereinafter simply referred to as "head").
Ultrasonic waves are emitted toward the object to be measured (sometimes referred to as ``transmission''), and the ultrasonic waves reflected by the object are received by the ultrasonic transmitting/receiving head. Measuring the distance to an object.

However, the speed of sound waves is greatly affected by the conditions of the environment being measured, such as temperature. For this reason, conventionally, a temperature compensation circuit having a temperature sensing element (thermistor) has been incorporated into an ultrasonic distance meter to correct the measured distance.

Alternatively, instead of using the temperature compensation circuit type described above, the ultrasonic transmitting/receiving head and the ultrasonic receiving head are placed on the same surface facing the object to be measured with a required distance between them, and the ultrasonic receiving head is connected to the ultrasonic receiving head. Ultrasonic waves are emitted towards the object to be measured and the reflected waves are received, and the reflected waves are also received by an ultrasonic receiving head that is a certain distance apart. It has also been proposed to measure the measurement distance (Japanese Patent Laid-Open No. 51-99563).

(Problems to be Solved by the Invention) Among the conventional examples mentioned above, the former temperature compensation circuit type corrects the measurement distance based on the temperature near where the thermistor is installed, so the distance to the object to be measured is long. However, there was a problem in that the measured distance could not be corrected accurately.

In addition, in the latter method using two heads, the reflected waves must be received at separate positions on the same surface, so it is necessary to prepare a head with a wide directivity angle, and the structure makes it difficult to position both heads. and operational shortcomings were rare.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention provides ultrasonic waves that transmit ultrasonic waves toward an object to be measured and receive ultrasonic waves reflected from the object to be measured. a transmitting/receiving head; an ultrasonic receiving head that is installed in the same direction as the ultrasonic transmitting/receiving head and at a predetermined distance from the object to be measured, and receives ultrasonic waves reflected from the object to be measured; It is characterized by comprising a calculation section that calculates the time required for the ultrasonic transmitting/receiving head and the ultrasonic receiving head to receive the emitted ultrasonic waves, and the measured distance from the predetermined interval to the object to be measured. .

(Function) Since the present invention has the above-described configuration, the ultrasonic wave transmitted from the ultrasonic transmitter/receiver head is received by the ultrasonic transmitter/receiver head, and the ultrasonic wave is always transmitted at a predetermined distance apart in the direction of the same directivity. The ultrasonic receiving head receives signals with a time difference. The distance to the object to be measured is calculated and measured from the time required for each of the heads and the distance of the predetermined interval between both heads.

(Example) An embodiment of the present invention will be described based on the drawings.

FIG. 1 schematically shows how a distance l to an object to be measured a is measured by an ultrasonic distance meter according to the present invention, where 1 is an ultrasonic transmitting/receiving head and 2 is an ultrasonic receiving head. The head 2 has the same directivity direction as the head 1, and is provided at a position set back from the head 1 by a predetermined distance d.

Reference numeral 3 denotes a measuring section which outputs an ultrasonic signal to the head 1, inputs signals received by both heads 1 and 2, and calculates a measured distance.

Both heads 1 and 2 are constructed so as to be oriented in one piece, as shown in FIGS. 2 and 3. That is, on the front side (Figure 2), head 1 is on the top, head 2 is on the bottom, and on the side (
In FIG. 3), the head 1 is located at the front and the head 2 is located at the rear.

Both heads 1 and 2 have cone-shaped recesses 3 and 4, and conical equalizers 5 and 6 are provided at the top of the cone to equalize the ultrasonic waves. A ring-shaped vibrator 7 surrounds the equalizers 5 and 6,
8 are provided respectively.

In this example, head 1 is placed upward, and head ? Although it is possible to position it so that it is at the bottom, it is also possible to reverse this. Furthermore, although the heads 1 and 2 are positioned so that the head 1 is in the front, they may be positioned in the opposite manner, that is, with the head 1 in the rear. However, if the head that transmits the ultrasound is at the rear, the ultrasound transmission will be obstructed by the head at the front.
As in the illustrated embodiment, the head that emits ultrasound waves is preferably located at the front.

When ultrasonic waves are transmitted from head 1 to object a from both heads configured as described above, head 1 transmits 1
After 1 second, the head 2 receives the reflected wave from the object to be measured 12 seconds later than tl.

Now let the speed of sound be v (m/S), and the distance to the object to be measured be l
(If m>, the following equation holds true.

vxt+=2. e...(1)vx
t2=2. g+d m (2>If ■ is deleted from the above two equations, the following three equations are established.

! =1.・d/2(i2 L+)...(3) This (3
) In the equation, d is a fixed distance between heads 1 and 2, so it is a known value. Therefore, in the end, t1 and t2
By measuring , the distance to the object to be measured can be measured.

Therefore, in the present invention, the relationship among g, d, t+, and t2 is calculated by the measuring section 3.

FIG. 4 shows the electrical configuration of this measuring section 3. Here, reference numeral 31 denotes a transmission driver, which operates to provide a timing signal to an ultrasonic output signal amplifier 32), an analog switch 33, and a logic operation section to be described later. By the output of the ultrasonic output signal amplifier 32 that received the timing signal,
The vibrator 7 of the head 1 is vibrated to emit ultrasonic waves toward the object to be measured a.

On the other hand, the ultrasonic waves (reflected waves) reflected by the object to be measured a are received by the heads 1 and 2, but first the front head 1
will be received. This reception is performed by the analog switch 33. which is switched by the timing signal of the transmission drive section 31.
The received signal is input to the received signal amplifier 35 via the analog switch 34 and amplified there. After noise is cut from the amplified signal by a band pass filter (BPF) 36, the signal waveform is shaped by a waveform shaping circuit 37, and the signal is input to a logic operation section 38.

Further, after inputting the signal from the head 1, the logic operation section 38
The signal is output to the analog switch 34 so as to switch the analog switch 34. As a result, the signal received by the head 2 is transferred to the analog switch 3 in the same way as the signal received by the head 1 described above.
4. Reception signal amplifier 35, BPF 36. The signal is then input to the logic operation unit 38 via the waveform shaping circuit 37.

On the other hand, this logic operation section 38 includes the above-mentioned transmission drive section 3.
Since the timing signal for ultrasonic transmission is also input from 1.1, the required time for both heads is determined from the timing at which head 1 and head 2 receive it. ．． 12 is calculated. Further, since the known distance d is also set in advance, the conditions for processing the above-mentioned equation (3) are satisfied, and the distance l to the object to be measured can be calculated. Although not shown, the logic calculation unit 38 outputs the calculation result to a display unit that displays the measured distance l.

(Effects of the Invention) The present invention includes an ultrasonic transmitting/receiving head and an ultrasonic receiving head arranged one behind the other in the same directivity direction, and a measuring instrument that calculates the measurement distance from the time difference in reception of reflected waves. With a head with a small directivity angle, it is possible to accurately measure distance without being affected by the environment such as temperature.

Moreover, if both heads are constructed integrally, the construction becomes simpler, and there is no need to manipulate the arrangement distance between both heads, and the distance measurement operation can be performed extremely easily.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a schematic explanatory diagram of the present invention, FIG. 2 is a front view of the head, and FIG.
The figures are a sectional view taken along the line A-A in FIG. 2, and FIG. 4 is an electrical configuration diagram. 1... Ultrasonic transmitting/receiving head 2... Ultrasonic receiving head 3... Measuring section

Claims (2)

[Claims] (1) An ultrasonic transmitter/receiver head that emits ultrasonic waves toward the object to be measured and receives the ultrasonic waves reflected from the object; an ultrasonic receiving head that receives the ultrasonic waves reflected from the object to be measured, which is provided at a constant distance; An ultrasonic distance meter comprising: a calculation section that calculates the measured distance to the object from each required time and the predetermined interval. (2) The ultrasonic distance meter according to claim 1, wherein the ultrasonic transmitting/receiving head and the ultrasonic receiving head are integrally constructed.