JPH0384488A - Ultrasonic distance measuring instrument - Google Patents

Abstract

PURPOSE:To measure up to a long distance and to shorten the measurement time by making the numbers of ultrasonic wave transmitters and receivers which are driven at the same time smaller for a shorter distance and larger for a longer distance. CONSTITUTION:This distance measuring instrument drives all ultrasonic wave vibrators 3 at the same time within a range of longer than a preset distance and when measurement data on shorter than a set distance is obtained, the number of ultrasonic wave vibrators 3 which are driven according to the distance is decreased with the distance to decrease output sound pressure and reception sensitivity as the distance is short, thereby measuring the distance in the best state according to the distance. Namely, an unnecessary area due to a side lobe is hardly formed and even when a short distance is measured, an unnecessary reflected signal is hardly generated, so the measurement time can be shortened.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an ultrasonic distance measuring device that obtains distance information using ultrasonic pulse signals. This ultrasonic distance measuring device is used as an obstacle detection device for vehicles, etc.

[Conventional technology]

A conventional example is shown in FIG. In conventional ultrasonic distance measuring devices, in order to increase the measurement distance, multiple ultrasonic transducers ■ to [phases] are driven by a drive device ■.
By driving simultaneously (both transmitting and receiving waves), the output sound pressure and receiving sensitivity were multiplied by the number of transducers (1) to [phase], making long-distance distance measurement possible. (2) is a signal processing device that performs such processing.

[Problem to be solved by the invention]

However, if a plurality of transducers are driven simultaneously, long-distance detection becomes possible, but conversely, the signal level becomes too high at short distances. In other words, when performing short-distance detection, unnecessary detection areas may occur due to side ropes, etc., and the next detection operation cannot be started until unnecessary reflected signals from long-distance areas disappear, resulting in a slow detection response speed. There are problems such as delays.

[Means to solve the problem]

The present invention provides an ultrasonic distance measuring device configured to simultaneously drive a plurality of ultrasonic transmitters and receivers toward the same sound field region. This ultrasonic distance measuring device is characterized in that the number of drives of the receiver is decreased at short distances and increased at longer distances.

[For production]

For example, when there is no detection or within a range greater than a preset distance, all ultrasonic transducers are driven simultaneously, and when measurement data within the set distance is obtained, depending on the distance, The number of ultrasonic transducers to be driven is
By decreasing the distance as the distance approaches, the output sound pressure and reception sensitivity are reduced at the short distance, allowing distance measurement to be performed in an optimal state depending on the distance.

Therefore, according to the present invention, measurement can be performed under optimal conditions depending on the distance of the object to be measured.

In other words, unnecessary areas due to side ropes are less likely to occur, and unnecessary reflected signals are less likely to occur even during short-distance measurements.
Measurement time can be shortened.

〔Example〕

Hereinafter, one embodiment of the present invention will be shown based on FIG.
■, ■, ■ are ultrasonic transducers, ■, ■, ■, [phase] are acoustic horns, and both constitute an ultrasonic transmitter and a receiver.
This ensures arbitrary directivity. 2 is an ultrasonic transducer driving device that drives the ultrasonic transducers 2, 2, 2, and 2 to transmit waves, and also takes in reception signals at times other than when transmitting waves. 2 is a signal processing device, which performs wave transmission timing and reception signal processing. ＠ is a switch device, which receives transducer control signals (a) and (b) from the signal processing device.
) to select one of the ultrasonic transducers (■, -■, ■, ■) to be driven.

In this example, four ultrasonic transducers ■, ■, ■, ■ are used.
This shows the case where the signal processing device uses the ultrasonic transducer ■, ■, ■ when the reflected wave exists and the distance is within the set range. , (2) is output as a 2-bit signal and sent to the switch device @ to select the ultrasonic transducer to be driven.

〔Effect of the invention〕

As described above, according to the ultrasonic distance measuring device of the present invention, ■ Can measure distances over long distances.

■ Distance can be measured even at short distances under optimal conditions.

■ Detects objects to be measured at short distances with a flat response speed.

There is an effect.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a block diagram showing a conventional example. ■ is a signal processing device, ■ is a drive device, ■, ■, ■, ■ is an ultrasonic vibrator, ■, ■, ■, [phase] is an ultrasonic horn.

Claims (1)

[Claims] (1) In an ultrasonic distance measuring device configured to simultaneously drive a plurality of ultrasonic transmitters and receivers toward the same sound field region, the ultrasonic transmitter and receiver are driven simultaneously. An ultrasonic distance measuring device characterized by reducing the number of drives of the receiver at short distances and increasing it at longer distances.