JPS59120875A - Ultrasonic object detector - Google Patents

Abstract

PURPOSE:To achieve a larger application range and a higher distance measuring accuracy by providing ultrasonic transmitting and receiving elements separately in the inner part of L-shaped ducts. CONSTITUTION:This detector is equipped with a pair of L-shaped transmitting and receiving ducts 6 and 11 housed in a detector section case 1 and the ducts 6 and 11 have a refracting section 7 at an L-shaped corner section thereof and an ultrasonic transmitting element 4 and an ultrasonic radiating section 5 and an ultrasonic receiving element 9 and an ultrasonic receiving section 10 at the inner end section thereof. These ducts are set downward with such an opening angle theta that the center axes 13 and 14 of radiation and receiving directivity thereof 6 and 11 expand relatively in the direction of ultrashort wave radiation and a sound absorbing member 16 is provided on the surface 2 of the detector section between the ducts 6 and 11 to prevent ultrasonic interference. This reduces the interference due to a multiple reflection of a radiation ultrasonic signal to prevent rain drops and dirts from attaching to the main section inside the ducts thereby enabling a higher distance measuring accuracy and a larger application range.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ultrasonic object detection device that detects objects at a distance using ultrasonic signals.

In a conventional ultrasonic object detection device, the detection section is the first
As shown in the figure, the detection unit case 1 includes a pair of ultrasonic transmitting element 4 that emits an ultrasonic signal toward a detection object 3 and an ultrasonic receiving element 9 that receives the reflected ultrasonic signal. Ultrasonic transmitting elements 4,
Corresponding to the ultrasonic receiving element 9, an ultrasonic emitting section 5 and an ultrasonic receiving section 10 were arranged facing the detection direction. Between the ultrasonic wave emitting unit 5 and the ultrasonic wave receiving unit 10, the ultrasonic signals emitted three-dimensionally into the air from the ultrasonic wave emitting unit 5 are not reflected by the sensing object 3 and are transmitted to the ultrasonic wave receiving unit 10. In order to prevent ultrasonic signals directly entering, that is, leakage waves, they are separated by a certain distance, and the sensing part surface 2 between them is flat or nearly flat, and has a shape and material with a high ultrasonic reflectance. Therefore, when the surface of the sensing object 3 is also flat or nearly flat, and has a shape and material with a high ultrasonic reflectance, the ultrasonic waves emitted from the ultrasonic radiator 5 are the radiated ultrasonic signal 1 shown by the dotted line in FIG.
8 and the reflected ultrasonic signal 19, the radiated ultrasonic signal 16 and the received ultrasonic wave to be detected undergo multiple reflections between the surface of the sensing object 3 facing each other and the sensing unit surface 2. It interferes with and affects the signal 17, and as shown in FIG.
is facing the sensing object 3, so the ultrasonic radiation components in two directions on the surface of the sensing part between the ultrasonic emitting part 5 and the ultrasonic receiving part 10 are large, and therefore interference due to multiple reflections is likely to occur. For this reason, as described above, there is a drawback that there are many leakage waves that are not reflected by the sensing object 3 and directly enter the ultrasonic wave receiving section 10 from the ultrasonic wave emitting section 5.

The present invention has been made to eliminate the above-mentioned drawbacks, and includes a pair of L-shaped transmission duct and reception duct housed in a detection unit case, and the duct has a bending part and a bending part at the corner of the L-shape. An ultrasonic transmitting element, an ultrasonic emitting part, an ultrasonic receiving element, and an ultrasonic receiving/receiving part are provided at the recessed inner end of the L-shape toward the duct. - Due to the opening angle θ such that the center axis of the wave receiving directivity relatively expands toward the ultrasonic direction, and the provision of a raised sound-absorbing material body on the surface of the detection part between the ducts to prevent ultrasonic interference. When the detection unit is placed facing the sensing object, interference due to multiple reflections of the emitted ultrasonic signal is less likely to occur, and there is little effect on the object detection signal, so the sensitivity is less affected by the shape, material, size, etc. of the sensing object. It provides a structure that has less unevenness, reduces leakage waves, prevents raindrops and dirt from adhering to the main inner parts of the transmission and reception ducts, and expands the range of use and distance measurement accuracy.

An embodiment of the present invention will be described below with reference to the drawings.

The structure of the embodiment is shown in the plan view of FIG. 3 and the sectional view taken along the line AA in FIG. Reference numeral 2 denotes the surface of a detection section, and 3 a detection object.The detection section surface 2 of the detection section case 1 is provided on the side facing the detection object 3. 4 is an ultrasonic transmitting element, 5 is an ultrasonic radiation section, 6
is an ultrasonic transmission duct, which forms an L-shaped waveguide and has a rectangular cross-section in the ultrasonic passing direction.
The ultrasonic wave transmitting element 4 and the ultrasonic radiation section 5 are installed in the inclined surface of the L-shaped corner part of the ultrasonic wave reflecting refraction part 7, and the ultrasonic wave transmission element 4 and the ultrasonic emission part 5 are installed in the recessed inner end of the L shape, facing toward the refraction part 7. An ultrasonic radiation opening 8 is provided at the end. 9 is an ultrasonic receiving element, 10 is an ultrasonic receiving section, 11 is a receiving duct,
The receiving duct 11 has the same shape as the transmitting duct 6, and the receiving duct 11 has an inclined ultrasonic reflecting refraction part 7 at the L-shaped corner, and the ultrasonic receiving element 9 and the ultrasonic receiving element 9 at the recessed inner end of the L-shape. A sound wave receiving section 10 is installed facing toward the refracting section 7, and an ultrasonic wave receiving opening 12 is opened at the other end. The transmitting duct 6 and the receiving duct 11 having the ultrasonic transmitting element 4 and the ultrasonic receiving element 9 are made into a pair, and the respective radiation apertures 8 and wave receiving apertures 12 are directed toward the sensing object 3 into the sensing part case 1. It is for storage. 13 is the central axis of radiation directivity of the transmitting duct 6, 14 is the central axis of receiving directivity of the receiving duct, and the distance between the central axis of radiation directivity 13 and the central axis of receiving directivity 14 is relatively in the ultrasonic radiation direction. The opening angle θ is set such that the opening angle increases along the direction.

15 is an ultrasonic buffer section, which is located on the detection section surface 2 of the detection section case 1.
The transmitting duct 6 and the receiving duct 11 are provided so as to form a bulge in the waveform of an arcuate peak.

Reference numeral 16 denotes a sound-absorbing material body made of thick cloth, felt, porous rubber, plastic, or the like, and is provided on the corrugated surface of the arcuate peaks formed in the ultrasonic buffer band 15. Note that the detection unit case 1 includes an ultrasonic wave emitting unit 5 and an ultrasonic wave receiving unit 1.
It is installed with 0 facing downward. The ultrasonic object detection device is equipped with a detection section having the above configuration.

In the above configuration, its operation is as follows. A shape with a flat or nearly flat surface and a high ultrasonic reflection.
When the detection object 5 of different material and size and the detection unit face each other in parallel, the radiated ultrasonic signal 16 output from the ultrasonic transmitting element 4,
18 is three-dimensionally radiated into the air from the radiation opening 6 of the transmission duct 6, among which the radiated ultrasonic signal 16 that detects the sensing object 5 hits the sensing object 3 and is reflected and becomes the received ultrasonic signal 17. The ultrasonic wave enters the receiving duct 11 through the receiving opening 12 and is converted into an electrical signal by the ultrasonic receiving element 9, and the electrical signal is sent to a control circuit (not shown) to determine the presence or absence of the sensing object 3 or to measure the distance. Let's do it. On the other hand, a radiation ultrasonic signal 18 other than the object detection signal, for example, shown by a dotted line, becomes a reflected ultrasonic signal 19 after hitting the sensing object 3 and being reflected. Since the sonic buffer zone 15 is provided, there is no parallel plane between the surface of the sensing object 3 and the sensing part surface 2, making it difficult for multiple reflections of the ultrasonic signal to occur, and attenuating the radiated ultrasonic signal to become the object detection signal. 16. The influence on the received ultrasonic signal 17 is also small. Note that other than the reflected ultrasonic signal 19 that hits the detection object 5 and is reflected and returns to the sound absorbing material body 16 and the ultrasonic buffer zone 15, those that are incident at an angle where they are not reflected again are attenuated by the sound absorbing material body 16 and multiplexed. It absorbs repeated reflections and eliminates interference as above. Furthermore, since the transmitting duct 6 and the receiving duct 11 have an opening angle θ, even if the sensing object 3 and the sensing unit face each other parallel to each other in front, the central ultrasonic waves with high radiation intensity will be emitted from the radiation opening 8. Since the signal hits the detection object 3 at an angle according to the opening angle θ, the component reflected in the direction of the receiving aperture 12 is smaller than that of the signal without the opening angle θ, as in the inappropriately reflected ultrasonic signal 20. is dissipated outside the receiving range, and interference due to multiple reflections is inherently less likely to occur. In this manner, as shown in FIG. 5, the directivity characteristics exhibit good performance with no decrease in sensitivity even near 0° in the center between the radiation aperture 8 and the reception aperture 12. Furthermore, since the ultrasonic transmitting element 4 and the ultrasonic receiving element 9 are installed at the inner part of the L-shaped transmitting duct 6 and receiving duct 11, raindrops and dirt do not attach directly to them, so they can be used not only indoors. It can also be used outdoors.

According to the present invention, there is provided a transmitting duct and a receiving duct in which the ultrasonic transmitting element and the ultrasonic receiving element are respectively installed in the inner part of the L-shape, and the ultrasonic transmitting element and the ultrasonic receiving element are emitted and received. Detection is achieved by setting an opening angle θ that relatively expands the center axis of the wave directivity, and by installing a wave-shaped sound absorbing material body of an arcuate mountain between the radiation amount opening and the wave receiving opening of the transmitting duct and receiving duct. When the part faces the sensing object, it attenuates the multiple repeated reflections of the radiated ultrasound signal and also absorbs and attenuates some of the multiple reflection ultrasound signals, making it difficult for their interference to occur.
It has little influence on the object detection signal, and is therefore less affected by the shape, material, size, etc. of the object to be detected.In other words, there is less unevenness in sensitivity, and it reduces leakage waves. It has the effect of expanding distance measurement accuracy and range of use, since raindrops and dirt do not adhere to the surface.

[Brief explanation of drawings]

Figure 1 is a top sectional view of a conventional ultrasonic object detection device;
The figure is a directivity characteristic graph of the same ultrasonic object detection device, FIG. 3 is a top sectional view of the ultrasonic object detection device showing one embodiment of the present invention, and FIG. 4 is an A-A arrow arrow of the same ultrasonic object detection device. The cross-sectional view in FIG. 5 is a directional characteristic graph of the ultrasonic object detection device. DESCRIPTION OF SYMBOLS 1...Detection part case, 2...Detection part surface, 4...Ultrasonic transmission element, 5...Ultrasonic emission part, 6...Transmission duct, 7...Refraction part, 9. ...Sound wave receiving element, 10...Ultrasonic wave receiving section, 11...Receiving duct, 13...Radiation directivity center axis, 14...Wave directivity center axis, 16...Sound absorbing material Body, θ... Opening angle. Applicant: Hitachi Thermal Appliances Co., Ltd. Figure 1/- Figure 3 Kawahai Figure 2 Qilu Figure 4 +90°

Claims (1)

[Claims] It has a pair of L-shaped transmission ducts (6) and reception ducts (11) housed inside the detection unit case (1), and the ducts (
6) and (11) have a refraction part (7) in a part of the corner of the L shape, and an ultrasonic receiving element (4) and an ultrasonic emission part at the recessed inner end of the L shape toward the refraction part (7), respectively. (5), an ultrasonic receiving element (9), and an ultrasonic receiving section (10), which are installed in a downward position, and furthermore, the duct (6), (11
) is an opening angle (θ) such that the central axes (13) and (14) of the radiation/reception directivity of
and the detection part surface (2) between the ducts (6) and (11).
An ultrasonic object detection device characterized in that a sound-absorbing material body (16) for preventing ultrasonic interference is provided at the top.