JPS635290A - Body detection sensor - Google Patents

Abstract

PURPOSE:To detect an invasion body, by comparing the shape of the change in the intensity of a reflected wave at the time of initial setting with that of the change in the intensity of a reflected wave at the time of usual warning. CONSTITUTION:The output of a counter circuit 9 is connected to the address indication part of a memory circuit 11 and the output of an amplifying/detection circuit 5 is connected to the circuit 11 on the side of INI by a mode change-over switch 12 through an A/D converter circuit 10 at the time of initial setting but connected to a comparing circuit 13 on the side of NORM at a usual time. In an initial setting mode, the reflection level within a definite time after ultrasonic transmission is stored in the circuit 11. In a usual mode, the reflection level subjected to AD conversion by the circuit 10 is compared with the initially set reflection level of the circuit 11 by the circuit 13 and, when the difference between the reflection levels comes to a definite value, a detection signal is outputted from the circuit 13. By the output of this detection signal, the presence of the invasion body different from a body preliminarily arranged in a warning area is detected.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an object detection sensor used for intrusion warning, etc., which transmits ultrasonic waves and detects the presence or absence of an object and intrusion based on the reflection time and intensity of the reflected wave. It is.

[Background technology] In general, object detection sensors for intrusion warning against intrusion through openings in houses, etc. include a hot-wire type that detects heat rays emitted from the human body, and a sensor that emits ultrasonic waves from a sensor and detects the reflected waves. There is an ultrasonic Doppler type that detects frequency changes, and an ultrasonic echo time type that detects the presence or absence of an object based on the reflection time of reflected waves. Among the various object detection sensors mentioned above, in the hot-ray type, it is difficult to select only the heat rays of the wavelength emitted by the human body, so it monitors the amount of change in radiant power in a certain range of wavelengths near the heat rays emitted by the human body. Therefore, in this case, the zero-order ultrasonic Doppler method used to detect the movement of the heat source uses the fact that the ultrasonic wavelength wave from the moving object deviates from the transmission frequency, so basically This is movement detection.

However, the movement detection type has the problem of having to detect only when the intruder moves at a certain speed or higher in order to prevent malfunctions. In some cases, there were undetectable problems. - The ultrasonic echo time type is a presence detection type installed as shown in Figure 3, for example, and does not have the above drawbacks, but in the case of this method, - after transmitting ultrasonic waves for a fixed time, Since it monitors whether there is a reflected wave from an object within a certain period of time, there are problems as will be discussed later.

An example of the circuit configuration of this system is shown in the block diagram of FIG. 4, and the operation of this example will be explained with reference to the time chart of FIG. 5 as follows.

The gate signal generation circuit 2 generates a transmission gate signal as shown in FIG. 5(a), and during this time the ultrasonic signal generation circuit 3 is operated as shown in FIG. The ultrasonic waves are amplified and transmitted by the ultrasonic microphone 1. The reflected ultrasonic waves as shown in (e) of the same figure are converted into electrical signals by the ultrasonic microphone 1, and then the reflected ultrasonic waves as shown in (d) of the same figure are converted into electric signals by the ultrasonic microphone 1.
If there is a reflected wave of − constant level L or higher within the period of the reception gate signal shown in FIG. outputs its output as shown in the same figure (f), and this detection result is held by the sample and hold circuit 7, and the same figure (f)
The object is detected and the detection result is output by outputting 0 or more as shown in g). Therefore, it is a presence detection type that detects the presence or absence of objects that reflect ultrasonic waves. However, this method also has drawbacks. For example, if there is an object in the warning range X as shown in the installation example in Figure 3, such objects such as the protruding parts of the window frame and plants (n) (I There is a problem. In this case, the reflected ultrasound is observed according to the distance from the ultrasound microphone 1 to the reflecting object, and
The received waveform will be as shown in (C') in the figure, and (d') in the same figure.
Since the detected waveform is as shown in FIG. 2, the level determination result is as shown in FIG. If it operates in this way, there is a problem that it cannot be used to guard against intruders. Therefore, it was necessary to remove the object within the warning range, change the installation angle of the ultrasonic microphone 1, or narrow the warning range so that the object was located outside the warning range. . However, it is often difficult to move objects within the warning range, and if the position or angle of the ultrasonic microphone 1 is changed or the warning range is narrowed, the warning range covers the opening that is originally intended to be monitored. In some cases, the warning range becomes too far away from the aperture surface, which poses a serious problem in practical use.

[Purpose of the Invention] The present invention has been made in view of the above-mentioned circumstances, and its purpose is to use an ultrasonic echo time type sensor to detect objects other than objects to be detected, such as intruders, within the warning range in advance. To provide an object detection sensor for intrusion prevention that does not output a detection output of the presence of an installed object.

[Disclosure of the Invention] FIG. 1 is a block diagram of a circuit configuration of an embodiment of the present invention. The configuration from the ultrasonic signal generation circuit 3 to the amplification/detection circuit 5 is the same as that of the conventional example.

Clock circuit 8 includes the functions of a conventional gate signal generation circuit. The output of the tarok circuit 8 is connected to the ultrasonic signal generation circuit 3, the counter circuit 9, and the A/D conversion circuit 10, and the output of the counter circuit 9 is connected to the addressing section of the memory circuit 11. The output of the amplification/detection circuit 5 is A
/D conversion circuit 10, and the output after conversion is:
When the mode changeover switch 12 is used, the memory circuit 11 is set during the initial setting on the INI side, and the comparison circuit 13 is set during the normal setting on the NORM side.
connected to. The comparison circuit 13 inputs the outputs of the A/D conversion circuit 10 and the storage circuit 11, and outputs a detection output when the difference therebetween exceeds a certain value.

Thus, the operation of the embodiment shown in FIG. 1 will be explained with reference to the time chart shown in FIG. First, the operation is roughly divided into two modes. There are two modes: initial setting mode and normal mode.

In the initial setting mode, the reflected wave level within a certain period of time after ultrasonic transmission is stored in the storage circuit as data converted by the A/D conversion circuit 10, and in the normal mode, the reflected wave level is stored in the storage circuit as data converted by the A/D conversion circuit 10.
By comparing the data converted by the /D conversion circuit 10 and the data stored in the storage circuit, the reflected wave level in the corresponding initial setting mode is compared, and a detection output is output when the difference is greater than a certain value. It is supposed to be done. First, Figure 2 (A) explains the initial mode in a little more detail.
are the waveforms of various parts in the initial mode. (a) in (a) of the same figure
) When transmitting ultrasonic waves as shown in (b) of the same figure, a received waveform as shown in (e) of the same figure is obtained.
At this time, the clock circuit 8 outputs a sampling signal as shown in FIG. 2(f) for a time corresponding to the conventional reception gate signal. At the timing of the sampling signal shown in (f) of the same figure, the A/D conversion circuit 10 performs A/D conversion on the detected waveform shown in (d) of the same figure, and outputs the numerical data of the black dots in (cl) of the same figure. . Further, the counter circuit 9 instructs the storage circuit 11 of the corresponding address by counting the sampling signal shown in FIG. 2(f).

Therefore, since the output of the A/D conversion circuit 10 is connected to the data input of the storage circuit 11, the constantly changing reflected wave level is stored in the storage circuit 11. Note that the counter circuit 9 is reset by the next transmission' signal. Further, one cycle is defined as the period from the ultrasonic wave transmission until the sampling signal as shown in FIG. 4(f) is completed. This storage operation is performed for one cycle or a plurality of cycles immediately after the initial setting is specified or after a certain period of time, and waveforms of various parts during the zero-order normal mode operation are shown in FIG. 2 (b). Memory circuit 11
The steps up to the address designation and the A/D conversion operation by the A/D conversion circuit 10 are the same as those in the initial setting mode, so the explanation will be omitted. The memory circuit 11 outputs the initially set reflected wave level at the same time after ultrasonic wave transmission as a stored value as shown in (g) in FIG. 13 can compare the reflection level at that time and the reflection level at the time of initial setting. When the difference in the level of reflected waves exceeds a certain value, the arrangement of objects in the warning area is different from that at the time of initial setting, and this is caused by an intruder or the like. Therefore, the comparison circuit 13 is
A detection output as shown in (h) of the same figure is output.

By repeating this cycle, you can always be on the lookout for intruders based on the changes from the initial settings. Note that in the cycle after the detection output, if the difference in reflected wave level is always below a certain value within that cycle, the comparison circuit 13 cancels the detection output.

[Effects of the Invention] As described above, the present invention uses an ultrasonic echo time type sensor to detect intrusion by comparing the shape of the change in reflected wave intensity during initial settings with the change in reflected wave intensity during normal warning. Since it is designed to detect objects, it is possible to provide a sensor used for intrusion warning, etc. that does not output a detection output to pre-installed objects within the warning range, but outputs a detection output to intruding objects. This sensor does not have the problems of movement detection type sensors, and has the effect of reliably solving the problems of presence detection type sensors.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a time chart during initial setting (a) and normal use (b), Fig. 3 is an example of installation of an object detection sensor for intrusion prevention, FIG. 4 is a block diagram of the conventional example, No. 57 is a time chart same as above, and (1) is an ultrasonic microphone. Agent Patent Attorney Ishi 1) Chief 71st Drawing 3rd Drawing 4th

Claims (1)

[Claims] (1) In an object detection sensor that detects the presence or absence of an object based on the intensity of reflected ultrasound that returns within a predetermined time after transmitting ultrasonic waves from an ultrasonic microphone, within a predetermined time during initial settings. storage means for storing a pattern of changes in the intensity of the reflected ultrasound waves, a comparison means for comparing the pattern of changes in the intensity of the reflected ultrasound waves within a predetermined period of time during normal use with the pattern stored in the storage means; An object detection sensor comprising: output means for outputting a detection output when a difference between comparison results by the means exceeds a predetermined value.