JPS6031076A - Ultrasonic detector - Google Patents

Abstract

PURPOSE:To achieve certain detection even if receiving influence such that a circumferential condition is varied, by enhancing detection sensitivity from the point of time when a receiving signal is detected. CONSTITUTION:A receiving wave amplifier circuit 6 receives the receiving wave signal of an ultrasonic vibrator 5 to amplify the same while the reflected wave is detected by a wave detecting and wave form shaping circuit 7. On the other hand, a comparator 8 discriminates the receiving wave signal while a signal processing circuit 9 is controlled by the receiving wave signal in a detection gate and an output circuit 10 fabricates an output signal to drive a relay. In this case, the gain of the circuit 6 is enhanced by a detection output signal.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to an ultrasonic detector that detects the presence of an object by projecting an ultrasonic signal and detecting a reflected signal.

(Background Art) Fig. 1 shows the detection area of an ultrasonic detector. 1st
The detection area shown in the figure is, for example, an area Et (indicated by a solid line) for detecting a cylinder having a diameter of 60U. However, due to the nature of the ultrasonic detector, this detection area is not constant within a certain range due to ambient conditions such as wind and wind (area Ez + Es indicated by a broken line in the figure).

Furthermore, it also depends on the installation conditions such as the inclination of the sensing object (in the above case, a cylinder with a diameter of 60 km). Also, for a cylinder with a diameter of 60 mm, the detection area shown in Figure 1 can be obtained, but for a cylinder smaller than 60 II in diameter, for example, a cylinder with a diameter of 50 M, it will be much narrower (area E4 in Figure 2). ), also has a diameter of 60 M
In a thicker cylinder, for example a cylinder with a diameter of 70 H, it presents a wider detection area (indicated by area E5 in FIG. 2). Note that in FIGS. 1 and 2, the person is an ultrasonic transducer.

Due to the characteristics of ultrasonic detectors, a detection object near the detection area limit may or may not be detected even if it is stationary in the vicinity, resulting in flickering of the output and The drawback was that it was not possible to obtain accurate output.

(Object of the Invention) The present invention was made in view of the above-mentioned drawbacks, and its purpose is to provide an ultrasonic detector that can consistently detect objects even near the detection area limit. .

(Disclosure of the Invention) Fig. 3 is a block diagram showing an embodiment of the present invention, in which the ultrasonic detector includes a periodic oscillation circuit 1 that outputs a signal at a constant period (for example, 70 m5eC), a gate generator that generates a gate signal, and a gate generator that generates a gate signal. Circuit 2.40K) (Ultrasonic oscillation circuit 3 that oscillates and transmits ultrasonic waves near , a receiving amplification circuit 6 and a detection/waveform shaping circuit 7 that detect the reflected wave, a comparator 8 that discriminates the received signal, a signal processing circuit that is controlled by the received signal in the detection gate, and a signal processing circuit that creates an output signal and operates the relay. It is constituted by an output circuit 10 for driving, and is configured to increase the gain of the wave receiving amplification circuit 6 using a detection output signal.

With this configuration, as shown in Figure 4,
The detection sensitivity increases from the time the received signal is detected, that is, the detection area expands, and even if the surrounding conditions change as described above, detection can be performed reliably (3). Furthermore, since the detection area expands after detection, for example, a detector sensitive enough to detect a cylinder with a diameter of 60 mm can also detect objects smaller than 60 mm in diameter. In addition, in Fig. 4, lal is the transmitted pulse, +bld is the received signal, tel is the detection output, (d)
is the detection sensitivity, and let is the detection area.

Next, FIG. 5 shows a different embodiment of the present invention, in which the reception sensitivity is reduced by lowering the threshold value of the comparator 8 for determining the total reception signal t, using different detection and detection output signals from the previous embodiment. It is the one that raised the. This embodiment also provides the same effects as the above embodiment.

(Effects of the Invention) As described above, in the present invention, the detection sensitivity increases from the time the received signal is detected, so it is possible to eliminate flickering in the output when an object exists near the detection area limit, and to ensure reliable A detection output signal can be obtained. In addition, after object detection,
Since the detection area is expanded, it is possible to detect objects that are smaller than those that can be detected under normal conditions.

(4)

[Brief explanation of drawings]

1 and 2 are characteristic diagrams showing the detection area, FIG. 3 is a block diagram showing an embodiment of the present invention, FIG. 4 is a time chart showing the operating state of the same, and FIG. 5 is a characteristic diagram showing the detection area. FIG. 3 is a block diagram showing different embodiments. Patent applicant Matsushita Electric Works Co., Ltd. Representative patent attorney Toshimaru Takemoto (#1 or 2 (5)

Claims (1)

[Claims] (1) By intermittently projecting the ultrasonic Barne signal and receiving and detecting the reflected waves from the sensing object, the presence of the object is detected, and the detection output signal is used to detect the detection sensitivity of the Nariotsu ultrasonic detector. An ultrasonic detector characterized by adding a detection sensitivity increasing means to increase the detection sensitivity.