JPS6281585A - Apparatus for detecting moving object - Google Patents

Abstract

PURPOSE:To reduce the length of the title apparatus without lowering efficiency, by forming the electromagnetic horn antenna connected to a Doppler sensor from a wave guide and a pyramidal horn connected thereto at a right angle and providing a reflective curved surface to the connection part of the wave guide. CONSTITUTION:In a moving object detection apparatus constituted by combining a microwave Doppler sensor 1 with an electromagnetic horn antenna 3, at first, a wave guide 5 transmitting the spherical wave from the Doppler sensor 1 is provided to the electromagnetic horn antenna 3. A pyramidal horn 4 approximately converting the spherical wave to plane wave is connected to the wave guide 5 at a right angle and a reflective curved surface curved so as to have a curvature reflecting a microwave at an angle of 90 deg. is provided to the part opposed to the wave guide of the pyramidal horn 4. By this method, the length of the apparatus can be reduced as a whole and required antenna efficiency can be secured.

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is used as an activation switch for detecting a moving object such as a human body and controlling the operation of a security alarm device or the opening/closing of an automatically opening/closing door. This invention relates to a moving object detection device.

<Prior art> Moving object detection devices that have been put into practical use so far include those using mat switches, those using the Doppler effect of radio waves or ultrasonic waves, and active devices that monitor the infrared flux emitted from a projector with a receiver. There are passive infrared systems that utilize fluctuations in the emitted infrared light flux based on the temperature difference between the background and the moving object. Among these, the one that utilizes the Doppler effect has a configuration in which a microwave Doppler sensor 1 and a pyramidal horn antenna 2 are combined, as shown in FIG.

A microwave Doppler sensor l is generally used with a low power of several mW to several tens of mW, and has a microwave oscillation section using a Gunn diode and a mixer diode that detects the Doppler signal built into it, and detects the inside of the detection area. Changes in frequency due to the passing of a moving object are detected using reflected received waves. Further, the pyramidal horn antenna 2 performs impedance matching between the microwave oscillation part of the Doppler sensor 1 and free space, and efficiently emits sharp upward radiation.

<Problems to be Solved by the Invention> By the way, since the pyramidal horn antenna 2 matches the impedance between the microwave oscillating part and the free space, its shape and dimensions are limited within the range naturally determined by the conditions of use. be done. In detail, pyramidal horn antenna 2
The length of the opening 2' and the opening area of the opening 2' are important factors in determining the directivity of radio waves. The efficiency (power gain) G of the horn antenna 2 has the following relationship, where λ is the microwave wavelength, A is the aperture area, and η is the aperture efficiency. Therefore, in order to increase the efficiency of the antenna 2, the aperture It is sufficient to increase the area A, but in order to increase the aperture area A, it is necessary to increase the length of the horn antenna 2. Generally, the length of the horn antenna 1 is designed to be three times the wavelength or more, and its opening angle is designed to be about 20 to 40" in order to easily convert it into a plane wave. For example, when using a 10.5 GHz microwave When using this, the wavelength is 2.850, so the length of the horn antenna 2 is designed to be 8.6 cm or more, which is about three times the wavelength.

Considering the entire device under the above conditions, if the length of the main body mechanism is added to the length of the Ho antenna 2 and the Doppler sensor 1, the entire device will be approximately 15 cm or more. It has a very elongated appearance. However, the installation location of this type of moving object detection device is often in conspicuous places such as the ceiling of a building, the upper part of a side wall, or the blind area of a door, and its shape is severely restricted from the viewpoint of interior design. There is a problem that the length cannot be shortened in order to obtain the required antenna efficiency. Moreover, since it has an elongated shape, it may be inconvenient to use depending on the installation location.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a moving object detection device that can secure a required antenna efficiency while having a horizontally elongated physique. It is something to do.

Means for Solving the Problems> In order to achieve the above object, the present invention provides a moving object detection device that combines a microwave Doppler sensor and an electromagnetic horn antenna.
A waveguide is provided on one side of the pyramidal horn in a direction perpendicular to the pyramidal horn, and the opposing surface of the waveguide on the pyramidal horn allows microwaves passing through the waveguide to be
The gist is that the reflection curved surface is formed with a curvature that causes reflection at an angle of 0°.

<Operation> With the above configuration, the microwave emitted from the Doppler sensor passes through the waveguide and is deflected in the radiation direction at an angle of 90'' by the reflective curved surface of the pyramidal horn. The spherical waves are converted into plane waves and radiated.Therefore, since the Doppler sensor is connected perpendicularly to the pyramidal horn, which is the main part of the electromagnetic horn antenna, through a waveguide, the length of the device is It will be shorter by approximately the length of the Doppler sensor.

<Example> Hereinafter, one embodiment of the present invention will be explained in detail.

1 and 2, the electromagnetic horn antenna 3 includes a pyramidal horn 4 having approximately the same shape as the conventional pyramidal horn antenna 2, and a flange 5' provided on one side of the pyramidal horn 4 in a direction perpendicular to the pyramidal horn 4. It is composed of a waveguide 5. The surface of the pyramidal horn 4 facing the waveguide 5 is formed into a reflective curved surface 4' having a predetermined curvature R to reflect the microwave at an angle of 90 degrees. Flange 5 of waveguide 5
' is fixed to a flange 1' of the Doppler sensor 1, and an electromagnetic antenna 3 is connected to the Doppler sensor 1.

The operation of the embodiment device configured as described above will be explained as follows.
The microwave radiated from the microwave oscillating part 1'' of the Doppler sensor 1 passes through the waveguide 5 and is reflected by the reflective curved surface 4', as shown by the broken line in FIG.
Deflected. This reflected radio wave is gradually and easily approximately converted into a plane wave in the pyramidal horn 4, and is radiated from the opening of the pyramidal horn 4. The curvature of the reflecting curved surface 4' is designed so that the relationship between the microwave oscillating part l"2 reflecting curved surface 4' and the reflected surface optically matches.

Since the Doppler sensor 1 is provided in an example part of the sensor 1 perpendicularly to the pyramidal horn 4, the longitudinal dimension B of the device required to obtain the required antenna efficiency is reduced by sharpening the directivity. However, compared to a device using a conventional straight pyramidal horn antenna, it is shorter by approximately the length of the Doppler sensor 1. According to actual measurements, the longitudinal dimension B of the device required to obtain the required antenna efficiency is
can be shortened by about 30% compared to the conventional one. Therefore, there are fewer restrictions on interior design for installing this, giving greater freedom, and the appearance of the installed state becomes more attractive.

<Effects of the Invention> As described above, according to the moving object detection device of the present invention, the Doppler sensor is provided in an example part of the electromagnetic horn antenna in the orthogonal direction, and the microwaves radiated from the Doppler sensor are deflected at 90° inside the antenna. Since the radiation direction is deflected at an angle of It has the advantage of being able to shorten the dimensions in the direction, giving greater freedom in interior design when installing it, allowing it to be installed in an attractive manner, and being easier to handle due to its smaller size. .

[Brief explanation of drawings]

1 and 2 are an exploded perspective view and a cutaway sectional view of an embodiment of the moving object detection device of the present invention, respectively, and FIG. 3 is a perspective view of a conventional device. 1- Doppler sensor 3--Electromagnetic horn antenna 4--Pyramid horn 4'-Reflection curved surface 5--Waveguide

Claims (1)

[Claims] (1) In a moving object detection device that combines a microwave Doppler sensor and an electromagnetic horn antenna, the electromagnetic horn antenna is provided with a waveguide on one side of the pyramidal horn in a direction orthogonal to the pyramidal horn, and A moving object detection device characterized in that a surface of the pyramidal horn facing the waveguide is formed into a reflective curved surface having a curvature that reflects microwaves passing through the waveguide at an angle of 90 degrees.