JPS6410136B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention detects the presence or absence of a moving object such as a human body within a predetermined detection area, and controls the opening/closing of an automatic door or the operation of a security alarm device. The present invention relates to an amplitude discrimination circuit that processes an analog detection signal in a moving object detection device used in a starting switch for detecting a moving object.

<Prior art> Among this type of moving object detection device, a non-contact type that is currently widely used uses differential detection of the difference between infrared energy emitted from a moving human body and infrared energy emitted from the background. There is a passive infrared type (infrared passive type). In this moving object detection device, radiant energy from a detection area set by the viewing angle of the optical system is focused on an infrared detection element such as a pyroelectric element by an optical system consisting of a mirror or lens; The change in radiated energy is converted into an electrical signal, and after this electrical signal is amplified, it is determined whether the amplitude is above the detection level, and if it is above the detection level, a signal is output. ing.

<Problems to be Solved by the Invention> By the way, the output signal from the infrared detection element is an analog signal that repeats 0.5 to 1 cycle at a frequency of 0.2 to 6 Hz, and is of a twin type in which a pair of infrared detection elements are operatively connected. Then, it becomes an analog signal that repeats 1 to 2 cycles. In other words, in this moving object detection device, a human body, etc. continues to enter and leave the detection area, so immediately after an output voltage is generated, a voltage with the opposite polarity is output, and furthermore, a heat source such as a human body to be detected is output. However, when the temperature is lower than the ambient temperature, such as during summer, the output voltage has the opposite polarity. In this way, the polarity and level of the output voltage of the infrared detection element differs when entering the detection area and when exiting the detection area, so this output voltage is compared at a constant level to detect moving objects. In order to obtain a signal, the output signal of the infrared detection element is individually amplified into a positive signal and a negative signal by a selective amplifier, and then the amplitude of each amplified signal is controlled by a level set individually for each polarity. Separate. Therefore, in order to individually discriminate the amplitudes of both positive and negative signals, two types of amplitude discrimination circuits, one for positive signals and one for negative signals, and an OR circuit to combine the outputs of both amplitude discrimination circuits are required. As the circuit configuration becomes more complex, the number of parts increases, leading to higher costs. Also, since the output signal of the infrared detection element is not very large,
There is a problem that the S/N ratio is not good.

The present invention has been made in view of these conventional problems, and is capable of discriminating the amplitudes of both positive and negative signals using a circuit configuration that is significantly simplified compared to conventional circuits, and is also capable of superior performance. A technical object of the present invention is to provide an amplitude discrimination circuit that can reliably detect a moving object when applied to a moving object detection device based on the S/N ratio.

<Means for Solving the Problems> In the present invention, as a technical means for achieving the above-mentioned problems, an amplitude discrimination circuit is configured as follows. That is, in an amplitude discrimination circuit that detects when the amplitude width of at least one of a positive signal or a negative signal from a signal input terminal exceeds a certain level, a charging resistor connected in series with the signal input terminal, respectively;
A positive signal CR integral consisting of a forward or reverse unidirectional element, a capacitor, and a discharging resistor that has a larger resistance value than each of the charging resistors and is connected in parallel to each of the unidirectional elements. circuit and a CR integrating circuit for negative signals, and setting the bias voltage of the CR integrating circuit for positive signals to be lower than that of the CR integrating circuit for negative signals,
The structure is characterized in that connection points between each of the unidirectional elements and the capacitor in both of the integrating circuits are connected to respective input terminals of a voltage comparator.

<Function> With the above configuration, each capacitor in each integrating circuit functions as a peak memory for positive and negative signals from the signal input terminal because the discharging time constant is larger than the charging time constant. ,
In addition, under normal conditions, the terminal voltage of the positive signal integration capacitor is lower than the terminal voltage of the negative signal integration capacitor, and the difference in voltage between these two capacitors during normal operation determines the comparator level of the voltage comparator, that is, the threshold voltage. is set. When a positive signal is input from the signal input terminal, the terminal voltage of the positive signal integration capacitor exceeds the above threshold voltage and becomes higher than the terminal voltage of the negative signal integration capacitor, or When the terminal voltage of the negative signal integrating capacitor exceeds the above threshold voltage and becomes lower than the terminal voltage of the positive signal integrating capacitor due to input of a negative signal, or when both positive and negative signals are input When the voltage of the signal integration capacitor increases and the voltage of the negative signal integration capacitor decreases, so that the voltage of the positive signal integration capacitor becomes higher than the voltage of the negative signal integration capacitor, the voltage of the voltage comparator is The output is inverted, and this inverted signal becomes a moving object detection signal when applied to a moving object detection device, for example. In this way, one amplitude discrimination circuit can discriminate the amplitudes of both positive and negative signals, and the amplitudes can be discriminated by adding up the absolute values of the changes in each of the positive and negative signals. In particular, when applied to a moving object detection device, positive and negative signals are output when a moving object crosses the detection area, so the terminal voltage of the positive signal integration capacitor increases, In addition, the terminal voltage of the negative signal integration capacitor is lowered, making it possible to reliably detect a moving object, and eliminating the influence of small-amplitude noise that is either positive or negative, and improving the S/N ratio. Much improved.

<Example> Hereinafter, a preferred example of the present invention will be described in detail with reference to the drawings.

In FIG. 1 showing an electric circuit according to an embodiment of the present invention, an input signal from a signal input terminal (not shown) is amplified by an amplifier 1, and a positive signal of this amplified signal is transmitted to a charging resistor 2. , diodes 3, 8
The positive signal integrating capacitor 10 is charged through the positive signal integrating capacitor 10, and discharged through the discharging resistor 7. On the other hand, the negative signal is charged in the negative direction through the charging resistor 2 and the diode 6 into the negative signal integrating capacitor 9, and is discharged through the discharging resistor 5. Furthermore, the diode 3 acts to lower the internal impedance by passing current through the resistors 2 and 4, and furthermore, the discharge resistors 5 and 7 have the same resistance value, and A resistor with a resistance value 100 to 200 times that of charging resistor 2 is used, and because the discharging time constant is much larger than the charging time constant, it can be used for positive signals and negative signals as described above. The respective capacitors 9 and 10 of each integrating circuit function as a peak memory with time-limiting characteristics. The terminal voltages of the capacitors 9 and 10 of each integrating circuit are input to the non-inverting input terminal + and the inverting input terminal - of the voltage comparator 11, respectively.

Next, the operation of the above embodiment will be explained with reference to FIG. 2 when applied to a moving object detection device. FIG. 2b shows the terminal voltage of each capacitor 9, 10, that is, the non-inverting input terminal of the voltage comparator 11 +
and the respective input voltage 1 of the inverting input terminal -
4 and 13 waveforms are shown. Normally, the negative signal integrating capacitor 9 is biased through the discharging resistor 5, whereas the positive signal integrating capacitor 10 is biased through the discharging resistor 5.
is biased through the diode 3 and the discharge resistor 7, so it is biased to a voltage lower than the negative signal integrating capacitor 9 by the voltage V2 between the terminals of the diode 3, and this difference voltage V2 is applied to the voltage comparator 11. This becomes the threshold voltage. With this setting of the threshold voltage V2, when a positive signal is input and the terminal voltage of the positive signal integrating capacitor 10 exceeds the threshold voltage V2 and becomes higher than the terminal voltage of the negative signal integrating capacitor 9, or When a negative signal is input and the terminal voltage of the negative signal integration capacitor 9 exceeds the threshold voltage V2 and becomes lower than the terminal voltage of the positive signal integration capacitor 10, the output voltage of the voltage comparator 11 is increased by either of the following: is reversed. This makes it possible to discriminate between the amplitudes of both positive and negative signals. Furthermore, even if only one of the positive and negative signals does not invert the output signal of the voltage comparator 11, both signals are output at a short time interval, and the absolute value of each change in both signals is outputted at a short time interval. The sum of the threshold voltage V2
When the voltage exceeds 0, the output voltage of the voltage comparator 11 is inverted. This operation will be explained below based on FIG. 2.

FIG. 2a shows the waveform of the output signal 12 of the amplifier 1, where V1 is the threshold voltage of the diodes 6 and 8, respectively. Since the amplitude of the positive signal indicated by S1 in FIG. 2a does not reach the threshold voltage V1 of the diode 8, the positive signal integrating capacitor 10 is not charged. In this way, regardless of whether it is a signal or a noise, those having an amplitude that does not reach the threshold voltage of the diodes 6 and 8 are blocked by the diodes 6 and 8 and are not charged in the capacitors 9 and 10. Therefore, continuous small amplitude noise such as white noise is blocked by the threshold voltage V1 of the diodes 6 and 8.

Next, since the amplitude of the positive signal portion of the signal indicated by S2 exceeds the threshold voltage V1 of the diode 8, the positive signal integrating capacitor 10 is charged.
4 does not rise to the extent that it exceeds the threshold voltage V2 of the voltage comparator 11 as shown in FIG. The voltage is not reversed as shown in c of the same figure. Therefore, noise that is spike-like and has a large amplitude but only occurs for a short time, such as an electric surge, is caused by the charging resistor 2 and the capacitors 9 and 10.
It will be absorbed by.

Then, when a human body crosses the detection area,
A signal as indicated by S3 is input, and since the amplitudes of both the positive signal and the negative signal exceed the threshold voltage V1 of the diodes 6 and 8, both capacitors 9 and 10 are charged. As shown in Figure b, first, the terminal voltage of the positive signal integrating capacitor 10 rises due to the positive signal portion, and is almost maintained at the increased voltage for a while due to the relatively long discharge time constant. Ru. In this way, with the voltage difference between both capacitors 9 and 10 becoming small, the negative signal integrates the negative signal and the capacitor 9 is charged in the negative direction, its terminal voltage decreases, and after a short period of time the negative signal integrating capacitor 9 is charged in the negative direction. The voltage becomes lower than the terminal voltage of the signal integration capacitor 10, and as shown in FIG.
output voltage is inverted. That is, a moving object detection signal is output. In this way, the amplitude is discriminated by adding the absolute values of the changes in both positive and negative signals, so when applied to a security alarm system, it is possible to detect illegal intruders into a home, etc. It is unthinkable for the area to remain completely stationary, and it usually moves slowly while observing the situation, so the difference between the terminal voltages of both capacitors 9 and 10 gradually decreases, in other words, the detection The sensitivity improved and finally both capacitors 9 and 1
Since an illegal intruder can be detected by reversing the zero terminal voltage, the S/N ratio is significantly improved and malfunctions due to noise can be reliably prevented.

This embodiment circuit includes one voltage comparator 11, 3
diodes 3, 6, 8, 4 resistors 2, 4,
5, 7 and two capacitors 9, 10, it is a circuit component that is almost equivalent to a single amplitude discrimination circuit of the two types provided in a conventional moving object detection device. It is composed of approximately half the number of circuit components.

<Effects of the Invention> Since the present invention is configured and operates as described above, it produces the following effects. That is, according to the amplitude discrimination circuit of the present invention, the amplitude of both positive and negative signals can be discriminated even though the circuit has about half the number of parts as compared to existing devices. Moreover, since amplitude discrimination can be performed by adding the absolute values of each change in both positive and negative signals, it is especially useful when applied to moving human body detection devices such as security alarm devices and automatic door activation switches. This has the great advantage of significantly improving the S/N ratio and reliably preventing malfunctions.

[Brief explanation of drawings]

Fig. 1 is an electrical circuit diagram of one embodiment of the present invention;
The figure is a waveform diagram of the operating voltage of each part in FIG. 1. 2...Charging resistor, 5,7...Discharging resistor,
6, 8...diode (unidirectional element), 9...
Capacitor for positive signal integration, 10... Capacitor for negative signal integration, 11... Voltage comparator.

Claims (1)

[Claims] 1. In an amplitude discrimination circuit that detects when the amplitude width of at least one of a positive signal or a negative signal from a signal input terminal exceeds a certain level, a charging resistor connected in series to the signal input terminal, forward or reverse a unidirectional element and a capacitor in the direction;
A CR integrating circuit for positive signals and a CR for negative signals, each comprising a discharging resistor having a larger resistance value than each of the charging resistors and connected in parallel to each of the unidirectional elements.
an integrator circuit, and the CR for the positive signal.
The bias voltage of the integrating circuit is set to be lower than that of each negative signal CR integrating circuit, and the connection points between the unidirectional elements and the capacitors in both integrating circuits are connected to each input of the voltage comparator. An amplitude discrimination circuit characterized in that it is connected to a terminal.