JPS5961793A - Ultrasonic distance measuring apparatus - Google Patents

Abstract

PURPOSE:To eliminate a measuring error caused by amplitude variation and to make it possible to always perform distance measurement with high accuracy, by discriminating a detection output based on an ultrasonic receiving wave through level discriminators or timers different in a threshold value. CONSTITUTION:The output of a detector 7 based on the reflected ultrasonic receiving wave from an object is inputted to discriminators 9, 12 respectively set to a small and a large threshold values in parallel. By the output of the discriminator 9, the counting of a counter 10 is stopped and an object distance calculation output is outputted through a latch circuit 15 while a timer 13 is operated. In addition, a gate 14 is opened during the timing period of the timer 13 and, when the output from the discriminator 12 is absent during this period, the output of the counter 10 is prohibited while the previous distance calculation output held in the circuit 15 is outputted and alarm generation is performed through an alarm output circuit 16. By this constitution, influence such as reflection loss and propagation loss are erased and distance measurement free from a measuring error caused by amplitude variation can be always performed with high accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic distance measuring device, and more particularly to a device that measures the distance to a target based on the propagation time of ultrasonic waves.

In the conventional ultrasonic distance measuring device, as shown in FIG. The ultrasonic pulse is emitted from the wave transmitter 3 (toward the target) and reflected from the wave receiver J to the RF amplifier B, and the detector V to the threshold value setter. When the reflection level is greater than the threshold value, it can be determined that there is reception for the first time, and the super i transmission time from transmission to reception is calculated by counter 10. However, in this conventional device, the reflected pulse from the target includes reflection loss at the target and transmission within the medium. (There was a change in reconnaissance for 1h, and it was impossible to always receive the reflected pulse of -7-foot width.
When a received pulse of amplitude cannot be received, as shown in Figure 2, the error (
The appearance of variations was unavoidable. gshi1
In the figure, this error (variation) is τ3. This variation is shown as τ2. τ2 is the maximum τ. corresponds to

In the same figure, a is the basic repetition period pulse, b is the transmitted pulse, C is the reflected pulse, and the pulse after dI/'i detection.

The present invention eliminates the drawbacks of the conventional ultra-high frequency distance measuring device, completely eliminates the effects of target reflection loss and propagation loss in the medium,
The object of the present invention is to provide an ultra-high wave distance measuring device that eliminates measurement errors caused by fluctuations in amplitude and can measure distances using just one eave from a high treetop.

The configuration will be explained below based on the embodiments of the present invention shown in Figure 43 and below.

FIG. 3 is a block diagram of the embodiment of the present invention; in FIG. 7 is a threshold value setter, 7 is a ml/level discriminator, 10 is a counter, and these are the conventional super It is the same as a wave distance measuring device. Further, in this embodiment, another 4λ level discriminator/vertical is connected to the output side of the detector 7 in parallel with the first level discriminator 7, and this co-level discriminator/ 2, a comparison is made with the second threshold value f set in the I ear 2 threshold setter //.

Note that this first threshold 111: f is set to be larger than the store/threshold value e. A gate is connected to the output side of this 4J level discriminator/2, and
The gate is in charge of opening the timer/3 which operates according to the output of the level discriminator. Also, /3 is a latch circuit, which is connected to the output side of the counter 10, and passes the output signal of the counter 10 only when the signal from the gate /3 is rare, and otherwise passes the output signal. has become a threat to deter Furthermore, /B is an alarm circuit that displays whether the current measurement output is normal or not, and is a reference repetition period pulse generator.

Signals are obtained from latch circuit/3 and gate/respectively 7
It has become.

This example has the same configuration as above, and an ultrasonic pulse b is emitted from the transmitter 3 toward the target in synchronization with the reference repetition period pulse a. , the reflected echo is received by the receiver j and amplified by the RF amplifier B (7, after detection by the detector 7, the detection output d is set in the 7th threshold setter g). In addition to the first level discriminator 7 that performs level discrimination with the threshold e, a, Zt, and threshold setter // have been set. 1) A first level discriminator that performs level discrimination with the threshold f. 7.2 is also fed in parallel.

Then, the reflected waveform is t/ and the second [7th threshold e.

When the value is larger than f, the output of the level discriminator starts driving timer/3.

Then, while the timer 73 is running, the second level discrimination %”+
It is determined by the gate /\ whether there is an output of /-2, and if there is, the output of the counter 10 is outputted via the latch circuit /j. or.

When the output d is smaller than the second threshold value f, there is no output from the second level discriminator /2, the latch circuit /2 suppresses the output of the counter 10, and the previous distance IIF information is held. The alarm signal can be output from the external output circuit/B. In other words, the -W timer 73 operates at the same time as the reception is determined by the output signal of the /3rd level discriminator, and the timer /3
During the operation, it can be determined whether the g2 level discriminator 7.2 outputs or not, and when this second level discriminator /) outputs, the counter 10 outputs new distance information and replaces the previous distance information. is updated, and when the channel rubel discriminator 7.2 does not output, the previous distance information is held until that point. Figure 49 shows this 5. This figure shows the waveform of the output signal at each part of the circuit of Example 1. In the section (1) in the figure, the reflection level is higher than both thresholds e and f, so the error due to the amplitude is It can be determined that it is small, and the output of the counter 10, that is, the measurement result, is output as is, but in the case of (If) and (1), the counter 10 is ! I tried to say this, but since the reflex level was too low, the error caused by the blood was determined to be a dog, and the output from the counter 10 was suppressed by the latch circuit /j.

The measurement result is not output, and the previous distance information is retained for the first time. Furthermore, in the case of (1v), the counter 10 itself does not function properly, and naturally the measurement result is not output, and the previous distance information is retained as is. Therefore, book '141f
In the lr example, only the reflected ultrasonic wave ζ having a large reflection level is selected and its propagation period is counted, so that no error occurs compared to the conventional method.

Next, the second embodiment of the present invention will be explained based on FIGS. 5 and 6. In this second embodiment, the operation of 5f, 2 counter/7 is stopped by the output of the first level discriminator. Compare the output of the first level discriminator with the 17th value set by the 43th threshold setter/gVC using the 3rd level discriminator/9, and the output of the first level discriminator is within this threshold value. In this case, the error due to the amplitude of the detection level is considered to be small, and the measured value is output from the latch circuit. Other parts are first
Components that are the same as those in the embodiment are designated by the same reference numerals, and description thereof will be omitted.

Note that in the above two embodiments, the detection output is discriminated by two Leben level discriminators to check the character of the signal, that is, the error. ? Needless to say, flff1 is further improved.

As explained above, in the present invention, by providing a plurality of level discriminators, the influence of reflection loss of the target and propagation loss in the medium is eliminated, measurement errors caused by fluctuations in the amplitude II are eliminated, and the It has an excellent effect of being able to accurately measure the distance to the target.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a conventional ultrasonic wave distance measuring device, Fig. 2 is a waveform diagram of the generated output of each part, Fig. 3 is a block diagram of the (H/embodiment) of the present invention, and Fig. FIG. 5 is a block diagram of the second example, and FIG. 6 is a waveform diagram of the output signals of each part. ) is a transmitting pulse generator, 3 is a transmitter, g is a target, j is a receiver, O is an RF amplifier, 7 is a wave detector, g is a threshold setter,
ri is a level discriminator, 10 is a counter, // is a second threshold setter, /2 is a second level discriminator, /3 is a timer, /ri is a gate, /3 is a latch circuit, /Otsu is a sound The report output is HI6. % Liver Applicant: Shimada Rika Koka Co., Ltd.

Claims (1)

[Claims] Ultrasonic pulses are emitted from the transmitter toward the target at each standard repetition period 7, and the reflected echoes are received by the receiver, which is then
In an ultrasonic distance measuring device that detects waves during F increase, discriminates reception by level-discriminating the detection output, measures ultrasonic propagation + iK time from transmission to reception with a counter7, and outputs it as distance information, the number of arrows is Level discriminators are provided in parallel, −
The threshold value of the power level discriminator is set to be smaller than that of the other level discriminator, and a timer is operated for a certain period of time at the same time as reception discrimination starts based on the output of the level discriminator with the smaller threshold. , determines whether or not the other level discriminator outputs during the operating time of that timer 7, outputs new distance information when this level discriminator outputs, and outputs new distance information when this level discriminator does not output. is the previous i+:l'
- An ultrasonic distance measuring device characterized in that it is configured to retain distance information as it is.