JPS583091A - Electric field type detector - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention (d) relates to an electric field type detector installed outdoors or the like to detect illegal intruders among visitors.

FIG. 1 is a schematic circuit block diagram of a conventional general electric field type detector.
1) and the earth (2), a detection signal voltage E. which is the oscillation output of an oscillator (3) consisting of a low frequency oscillator is applied. (4) is the detection line, and this detection line (4) is the excitation line (1
) is arranged horizontally with respect to K and connected to ground (2) via an input resistor RIM. (6) is a detection circuit, and this detection circuit (6) is amplified by an amplification circuit (6) and detects a change in the voltage across the input resistor RIM. (7
) is a cossiparator circuit, and this cossiparator circuit (7)
is connected to the detection circuit (
This is for inputting the detection output of 5) and detecting the change level, and when it exceeds a preset value, the KtJ next-stage notification circuit (9) is activated.

The operation of the circuit shown in FIG. 1 will be briefly explained with reference to FIG. 2, which shows a circuit equivalent to the circuit shown in FIG. 1, and an explanatory diagram of FIG. 3.

FIG. 3 shows the change in the induced voltage ve of detection #(41) that occurs due to the movement of the human body M relative to the position of the detection 11141. When moving away from the point, the capacitance ch between the human body M and the detection line (4) changes from ChI to Ch, or from Chl to Ch.
The induced voltage v0 changes from ■a to vo! or change from vo鵞 to vo:.

In FIG. 2, co indicates the capacitance between the detection line (4) and the ground (2), and the line indicates the line capacitance between the excitation line (1) and the detection line (4).

Now, when the above-mentioned change in the induced voltage v0 is detected by the detection circuit (6) and the change level is detected by the cosciparator circuit (7) via the Basid bus filter (8), when the change level exceeds a preset value, It activates the alarm circuit (9) and functions as a human body detector.

By the way, the oscillator (3) that puts the oscillation output on the excitation line itl
When the oscillation frequency of is set to a single fixed frequency, the detection line (4
) received commercial power supply harmonic components such as power supply hum noise and sweep noise, and oscillation output (hereinafter referred to as detection signal).
A beat is generated between the
In some cases, the signal may pass through and activate the cossiparator circuit (7), causing a false alarm.

Figures 4-) and (b) show the state of beat generation between the commercial power supply harmonic noise In- and the detection signal, and the commercial power supply harmonic noise ns is generated at intervals of the commercial power supply frequency (60 Hz intervals or 50 Hz intervals).
Hz interval), and the commercial power supply frequency signal frequency f
, the beat frequency is 20-odd Hz
Therefore, such a high frequency is determined by the above-mentioned bass filter (8) <0°08Hz''-0.3 for this type of detector.
The HzK band is set. > cannot pass through, and will not cause false alarms. However, as shown in Figure 4(b), the frequency of the commercial power supply fluctuates and the harmonic noise of the commercial power supply n
If the field fluctuates and generates a low-frequency beat between the commercial power supply harmonic noise n-, which is close to the detection signal frequency 70, the beat frequency will pass through the bassid bass filter (8) and cause a false alarm. There was a drawback.

Thinking about the cause of this, first of all, if the commercial power supply harmonic noise ins is far away from the detection signal frequency, it is not a problem.
It can be seen that the following) occurs.

Therefore, as shown in Fig. 5, no matter what frequency the commercial power supply harmonic noise ns is, the frequency f0 of the detection signal is
By frequency modulating the beat frequency, it is possible to drive the beat frequency to a higher range and prevent false alarms. However, in this case, for example, if the detection signal frequency 10 is modulated at 1 m, then f
A sideband of 0±fm is generated, and there is a risk that a beat will occur between the sideband and the commercial J source harmonic noise, so a filter must be provided to remove the harmonic noise near the sideband. Figure 6 is a block diagram of a conventional circuit based on the principle of Figure 5, and the oscillator means is a low frequency oscillator (3a
) and a voltage controlled oscillator (3b), the low frequency oscillator (
The frequency 10 of the voltage controlled oscillator (3b) is modulated with the oscillation frequency fm of 3a). 1101 is a notch filter,
This is to remove harmonic noise ns around the frequency of 10±fm.〇If we consider the cause of false alarms, the cause is that even when a single frequency detection signal is used, commercial power supply harmonic noise in+
s is the detected signal frequency f0 (this is the case where the distribution of the commercial power supply harmonic noise ns is determined as shown in Figure 7). Therefore, the harmonic noise component of the commercial power supply frequency and the detection signal frequency A circuit is installed to constantly monitor the beat frequency of f, and when the beat frequency is high enough to cause no problem, the single frequency f0 is used as the detection signal, and conversely, when it is low enough to cause a false alarm, the commercial There is a sideband wave f between the power supply harmonic noise ns and the commercial power supply harmonic noise in Hatake.
, -fm or f0+fm is used. In this case, low frequency beats that may cause false alarms will not be generated due to any fluctuations in the commercial power frequency. Using this principle, the notch filter in the circuit of FIG. 6 is unnecessary, resulting in the circuit shown in the block diagram of FIG. 18. When the switch SWi is on, the low frequency oscillator (button) modulates the detection signal whose frequency is fo, which is oscillated by the oscillator (3C), at the frequency fm in the phase modulator (river).This frequency fmd side band 0±fm is the frequency adjusted so that it is approximately in the center of the adjacent harmonic noise. (The phase adjuster outputs the frequency f0 when there is no control input voltage (when the switch SwI is off). The beat frequency monitoring unit 01 controls the switch SW that determines whether the modulator (11) outputs the 10 single frequency detection (IT signal or the FM modulated signal with fm). It is a circuit, i.e. an oscillator (
3) f. frequency, commercial power frequency fAco, high m
If the beat frequency with the wave noise ng is too high to cause a problem, switch SW1 is turned off, and if the beat frequency is low enough to pass through the bassid bass filter (8), switch SW1 is turned off. - It is designed to be kept at -.

As mentioned above, the cause of beat frequency generation is the excavation frequency f.
The problem is that the frequency of commercial power supply harmonic noise ns approaches 0. In addition to the above-mentioned repulsion method, there are the following methods to prevent the generation of low beat frequencies: In other words, when generating a low beat frequency that becomes a problem. Since the distribution of commercial power harmonic noise n8 is determined as K, if the frequency for of the detection signal is a problem, the oscillation frequency will change just before the low beat frequency occurs, as shown in Figure 9. This is a method to move the vehicle safely. In this case the frequency f
So that of does not become a problem (occurrence of high beat frequency)
If the frequency fog becomes a problem after selecting f,...
This means that Id can be a safe frequency. In this way, low frequency beats that would cause a problem are not generated due to any frequency fluctuations of commercial power supply harmonic noise inI, and W4 notification can be prevented.

10th Shows a block diagram of a circuit based on the above principle, (
The oscillator in 3) is capable of oscillating detection signals of two frequencies /as and fヮ, and when high 11 wave noise ns approaches the frequency fIL of one, the other frequency is set to the harmonic of one adjacent commercial power supply. The frequencies 701 and fa are adjusted to be approximately at the center between the wave noises ns. t7tt
The beat frequency monitoring circuit of the ts detects the harmonic components of the commercial power supply frequency 7AC and the beat of the detection signal frequency, and if a low beat frequency that causes a problem occurs, it will change one oscillation frequency to the oscillator (3). This method outputs a control signal to oscillate at
111fI1. There are ways to prevent this from happening, such as: In other words, the problem with the ts1 diagram circuit is that the beat between the commercial power supply harmonic noise ns and the detection signal passes through the Basidic filter (8), so the frequency 10 of the detection signal is As shown in the figure, if the commercial power supply harmonic noise nmK is made to match, the beat frequency will be OHZ.
), and no matter what commercial power supply frequency fluctuations occur, false alarms due to 4 beats are impossible.

FIG. 12 shows a schematic diagram of a circuit using the above-mentioned principle, using a voltage controlled oscillator as the oscillator (3). 0
The frequency divider 4 is used to divide the oscillation frequency of the oscillator (3) to reduce it to the commercial radio frequency 110, and the output is input to the phase comparator 11 where the phase is compared with the commercial power frequency zAa. , the phase comparator (l:1) controls the oscillator (3) by this phase comparison.

In this way, the oscillation frequency of the oscillator (3) is always fixed to an integral multiple (harmonic frequency) of the commercial power supply frequency fha by the loop of the oscillator (3), the divider 04, and the phase comparator I, and Harmonic noise does not generate beats between the four.

By the way, in each circuit of Fig. 8, Fig. 1θ, and Fig. 12 which do not use No. 1 Sochi filter t101, the commercial power supply frequency fA
A countermeasure against false alarms is taken using O, but this commercial power supply frequency fhc has conventionally been taken out just like the commercial power supply.

Therefore, there is no problem when the human body detector is operated with commercial power, but for example, when the commercial power to the human body detector is cut off and the human body detector is operated with DC power, such as battery backup, it becomes impossible to extract the commercial power frequency fAc. It had the disadvantage of giving away information.

The present invention has been made in view of the above-mentioned drawbacks, and its purpose is to obtain the commercial power frequency without directly extracting the commercial power frequency from the commercial power source, and to use the commercial power frequency to generate harmonics of the commercial power source. To provide an electric field type ring detector which prevents false alarms due to the beat frequency between noise and the frequency of a detection signal, and which can be used with both commercial power sources and DC power sources without causing false alarms.

The present invention will be explained below using examples. Figure 13 shows a schematic diagram of the circuit that is the basis of the present invention. In such a circuit, circuits having the same numbers as those in circuit program 1 in FIG. 1 have similar configurations and functions. In the figure, 9@ is a newly installed Basidopass filter, which passes only the commercial power frequency fAO induced in the detection line (4). The obtained commercial power supply frequency fAo signal is used to prevent beat frequency generation. FIG. 14 shows a block diagram of a circuit according to an embodiment of the present invention that can use an AC or DC power source, and an oscillator (3) consisting of a low frequency oscillator is used to detect two types of detection that differ in frequency by 30 Hz by an external control signal. The Basid bass filter alternately oscillates the signal and passes only the commercial power frequency fha induced by the test tube (4), and extracts the commercial power frequency 7AO signal. Then, the beat frequency detection circuit 1 generates a beat signal between the detection signal output from the oscillator (3) and the harmonic noise of the commercial power supply, and controls the oscillator +3 before a problematic low beat signal frequency occurs. It outputs a signal and shifts the detection signal frequency. This prevents false alarms due to commercial power source high 1111 wave noise.

In addition to the above-mentioned embodiments, it is of course possible to apply the present invention to a circuit that prevents false alarms by using the commercial power frequency fm0 signal as shown in FIGS. 8 and 12.
The present invention is not limited to the embodiment shown in the figure.The present invention is configured as described above, in which a bass filter is connected to the detection line and extracts the commercial power frequency that is guided by the detection line, and the extracted commercial power frequency is based on the detected commercial power frequency. Since the oscillation means is controlled so that the frequency of the detection signal is such that no low frequency beat occurs between the commercial power supply interharmonic noise and the frequency of the detection signal, the oscillation means is controlled so that the frequency of the detection signal is such that no low frequency beat occurs between the commercial power supply interharmonic noise and the frequency of the detection signal. Zhou@,
11 due to commercial power supply harmonic noise without entering the number.
#4 It is possible to prevent the alarm from occurring, and therefore it can be used with a DC power source, reducing the battery power consumption.
It has an excellent effect of not causing false alarms even during periods of shiku-a-shibu.◇

[Brief explanation of the drawing]

Figure 1 is a block diagram of a conventional circuit, Figure 2 is an equivalent circuit diagram of the same as above, Figure 3 is an explanatory diagram of the operation of the same as above, and Figure 4-
) 佽) #-i Figure -5 is an explanatory diagram of the generation of false alarms, Figure -5 is a diagram explaining the principle for preventing false alarms, Figure 6 is an oI diagram of a conventional circuit based on the principle of Figure 5, and Figure 7 is an illustration of the principle of preventing false alarms. Another diagram explaining the principle for preventing false alarms, Figure #18 is a circuit block diagram of a conventional example based on the principle of Figure 6, and Figure #9! J is a diagram explaining another principle for preventing false alarms, FIG. 10 is a circuit block diagram of a conventional example based on the principle of FIG. 9, FIG. 11 is a diagram explaining another principle for preventing false alarms, and FIG. 13 is a block diagram of a basic circuit of the present invention, and FIG. 14 is a block diagram of an embodiment of the present invention. (1)
is the excitation line, (2) is the ground, (3) is the oscillator, 14) is the detection line, and 7AO is the commercial power supply frequency Jl is the harmonic noise of the bent power supply. Agent Patent Attorney Ishi 1) Choshichi

Claims (1)

[Claims] l) An oscillating means is connected between the excitation line installed approximately parallel to the earth and the earth, and a detection signal voltage is applied based on the way the oscillation is output.
A level detection means for detecting the change level by detecting a change in the induced voltage of a detection line installed approximately parallel to the excitation line is connected to the detection line, and a bass filter is provided for extracting the commercial power frequency induced by the detection line. Connect to the detection line, and set the detection signal frequency so that low frequency beats do not occur between the commercial power harmonic noise and the detection signal frequency based on the extracted commercial power frequency. An electric field type detector characterized by controlling an oscillation means.