JPH0765261A - Human body detecting device - Google Patents

Abstract

PURPOSE:To provide the human body detecting device which does not require a reference electrostatic capacitor. CONSTITUTION:An electrostatic capacitor Cx which varies in capacity value as a human body approaches is connected between the inverted input terminal and output terminal of an operational amplifier 1. A resistor R1 is connected to the inverted input terminal and an integrator 2 is composed of the operational amplifier 1, the terminal of an oscillator 3 which outputs a rectangular wave voltage is connected to the input terminal of the integrator 2. A smoothing circuit 4 consisting of a resistor R2 and a capacitor C1 is connected to the output terminal of the integrator 2. The inverted input terminal of an operational amplifier 5 is connected to the output side of the smoothing circuit 4. A reference voltage Vr is inputted to the uninverted input terminal of the operational amplifier 5 to constitute a comparator 6. When the human body approaches and the capacity value of the electrostatic capacitor Cx increases, the output of the integrator 2 decreases and the input of the comparator 6 becomes less than the reference voltage Vr. Consequently, the output of the comparator 6 varies and then the human body is therefore detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a human body detecting device for detecting a human body by knowing a change in the capacitance value of the electrostatic capacitance due to the approach of the human body.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, a pair of detection electrodes 12 and 12 made of a metal sheet are attached to the inside of a toilet seat 11 made of resin, and a person sits on the toilet seat 11 to make this electrode. There is a human body detection device that detects the presence or absence of a human body by utilizing the fact that the electrostatic capacitance between 12 and 12 increases.

FIG. 6 shows a schematic circuit configuration diagram of the human body detecting device. As shown in FIG. 6, in this human body detecting device, the output of an oscillator 13 that generates an AC signal such as a sine wave or a triangular wave is inverted and amplified by an inverting amplifier formed by using an operational amplifier 18, and the electrodes 12 and 12 are connected to each other. Capacitance C
x is the input capacitance of the inverting amplifier, and the feedback capacitance is the reference capacitance C.
Since the capacitance Cx increases as the human body approaches as f, the amplification degree of the operational amplifier 18 increases, and an inverting amplified output (output proportional to Cx / Cf) corresponding to that is obtained, and the human body can be detected. is there.

Further, in order to reduce noise near the commercial power supply frequency mixed in from the power supply and included in the inverted amplified output, it is passed through a high-pass filter 14, full-wave rectified by a full-wave rectifier 15, and then amplified by an amplifier 16 and integrator. It is integrated at 17 and the DC voltage output is taken out. When the human body is detected, the amplification degree of the operational amplifier 18 increases and the DC voltage output also increases. Therefore, for example, only when the DC voltage output exceeds a predetermined value, that is, when a person sits on the toilet seat 11, It is used by turning on a switch such as an attached cleaning device (not shown).

[0005]

However, in the above configuration, since the AC signal is amplified by the ratio of the capacitance values of the two electrostatic capacitances Cx and Cf, the static capacitance serving as the reference for the electrostatic capacitance Cx to be detected. The capacitance Cf is required, and there is a problem in that the capacitance Cf serving as a reference has to be individually adjusted with respect to variations in the capacitance value of the capacitance Cx to be detected.

An object of the present invention is to solve the above problems, and an object thereof is to provide a human body detecting device having a simple structure which does not require a reference electrostatic capacitance.

[0007]

In order to achieve the above object, the invention of claim 1 connects an electrostatic capacitance, whose capacitance value changes when a human body approaches, between an inverting input terminal and an output terminal of an operational amplifier. Characterized in that the output terminal of the oscillator for outputting a rectangular wave voltage is connected to the input terminal of the integrator and the input terminal of the comparator is connected to the output terminal of the integrator via a smoothing circuit. .

According to a second aspect of the present invention, a first comparator is provided at an output terminal of an integrator which is formed by connecting a capacitance whose capacitance value changes when a human body approaches, between an inverting input terminal and an output terminal of an operational amplifier. And the input terminal of the first comparator is connected to the input terminal of the integrator, and the output terminal of the integrator is connected to the input terminal of the second comparator through a smoothing circuit. Is characterized by.

[0009]

According to the structure of the invention of claim 1, a rectangular wave is applied to the input terminal of the integrator which is connected between the inverting input terminal and the output terminal of the operational amplifier, and the capacitance of which changes when the human body approaches. Since the output terminal of the oscillator that outputs the voltage was connected and the input terminal of the comparator was connected to the output terminal of the integrator via the smoothing circuit, when the human body approaches and the capacitance value of the integrator becomes large, The output decreases, and as a result, the input of the comparator becomes smaller than the reference value and the output of the comparator changes, which allows the human body to be detected and does not require a reference capacitance. The human body detection device can be realized with a very simple structure.

According to the second aspect of the invention, the first terminal is provided at the output terminal of the integrator which is connected between the inverting input terminal and the output terminal of the operational amplifier and whose capacitance changes when the human body approaches. Since the input terminal of the comparator is connected, the output terminal of the first comparator is connected to the input terminal of the integrator, and the output terminal of the integrator is connected to the input terminal of the second comparator via the smoothing circuit. , By using the output of the first comparator as the input of the integrator, the first comparator is caused to self-oscillate and the rectangular wave voltage is input to the integrator, and the human body approaches and the capacitance value of the capacitance is changed. When it becomes larger, the oscillation frequency of the first comparator becomes lower, and as a result, the input of the second comparator smoothed by the smoothing circuit becomes smaller than the reference value and the output of the second comparator changes, whereby The human body can be detected, and the reference capacitance Without necessity, moreover it is the oscillator human body detection device with an extremely simple structure that does not require can be realized.

[0011]

Embodiments of the present invention will be described with reference to the drawings.
The following embodiments relate to the human body detection device used for the toilet seat described in the conventional example, but the present invention is not limited to this and the technical idea of the present invention can be applied to other devices. (Embodiment 1) As shown in FIG. 1, the human body detecting apparatus according to the present embodiment has a capacitance C whose capacitance value changes depending on the approach of a human body like capacitance between electrodes incorporated in a toilet seat (not shown).
The output terminal of the oscillator 3 for outputting a rectangular wave voltage to the input terminal of the integrator 2 in which x is connected between the inverting input terminal and the output terminal of the operational amplifier 1 and the resistor R ₁ is connected to the inverting input terminal. And the inverting input terminal of the operational amplifier 5 is connected to the output terminal of the integrator 2 via the smoothing circuit 4 including the resistor R ₂ and the capacitor C _1.
The comparator 6 is configured by inputting the reference voltage Vr to the non-inverting input terminal of the.

In the above structure, the peak value voltage V ₁ of the rectangular wave output of the oscillator 3 is V ₁ = 5V, and the capacitance of the electrostatic capacitance Cx when the human body is not approaching (when the person is not sitting on the toilet seat). When the value Cx ₁ is Cx ₁ = 20 pF, the charging current i flowing through the electrostatic capacitance Cx is i = 10 μA, and the charge charged in the electrostatic capacitance Cx is represented by Q, then Q = Cx ₁ · V ₁ = i · T Holds. Here, T is the time until the electrostatic capacitance Cx is fully charged. From the above equation, T = Cx ₁ · V ₁ / i = 20p
F · 5V / 10 μA = 10 μs. Here, assuming that the oscillation frequency of the oscillator 3 is 50 Hz (half cycle 10 μs), the output waveform of the oscillator 3 and the output waveform of the integrator 2 are shown in FIG.
The waveform is as shown in. That is, the output of the integrator 2 has a charge / discharge waveform having a peak at 5V. Here, when a person sits on the toilet seat, the capacitance value of the electrostatic capacitance Cx becomes large, so the time T until the above-mentioned full charge becomes long, and the half cycle time (10 μs) when the output of the oscillator 3 is 5V. )
Then, the electrostatic capacitance Cx is not sufficiently charged, and the peak of the output of the integrator 2 is lowered as shown in FIG. Integrator 2
Output is smoothed by the smoothing circuit 4 and input as a DC voltage to the comparator 6, where a person sits on the toilet seat, that is, the capacitance C.
When the capacitance value of x increases, the DC voltage input from the smoothing circuit 4 to the comparator 6 decreases and falls below the reference voltage Vr, and as a result, the output of the comparator 6 changes (becomes higher).
The detection output of the human body can be obtained as a change in output voltage.

(Embodiment 2) The human body detecting apparatus of this embodiment is
As shown in FIG. 3, the capacitance Cx is connected between the inverting input terminal and the output terminal of the operational amplifier 1, and the resistor R ₁ is connected to the inverting input terminal. 7 is connected to the input terminal of the first comparator 8 (non-inverting input terminal of the operational amplifier 7) in which the reference voltage Vr ₁ is input to the inverting input terminal of 7 and the output terminal of the first comparator 8 is connected to the integrator 2 Input terminal of the second comparator 10 connected to the output terminal of the integrator 2 through the smoothing circuit 4 and the reference voltage Vr ₂ input to the non-inverting input terminal of the operational amplifier 9 (of the operational amplifier 9). Inverting input terminal) is connected.

In the above configuration, while the output of the integrator 2 is lower than the reference voltage Vr ₁ of the first comparator 8, the first comparator 8
A constant output voltage is input to the integrator 2 to charge the electrostatic capacitance Cx. However, when the output of the integrator 2 becomes higher than the reference voltage Vr ₁ , the output of the first comparator 8 becomes zero, and the charge of the electrostatic capacitance Cx is discharged. When the electric charge of the electrostatic capacitance Cx is completely discharged, the first comparator 8 outputs a constant output voltage again to charge the electrostatic capacitance Cx, and thereafter, the above-mentioned operation is repeated.
As shown in (a) and (b), the rectangular wave voltage is input to the integrator 2 by causing the first comparator 8 to self-oscillate.

When the output voltage waveforms of the integrator 2 and the first comparator 8 are compared between a case where a person is seated on the toilet seat and a case where the person is not seated, as shown in FIG. 4 (a). As shown in FIG. 4B, when the person is seated, the capacitance value of the capacitance Cx is larger than that when the person is not seated. Becomes longer and the frequency of the output voltage decreases. If the output voltage of the integrator 2 is smoothed or integrated in the smoothing circuit 4,
Since the charge / discharge amount of the electrostatic capacitance Cx per unit time changes depending on the magnitude of the capacitance value of the electrostatic capacitance Cx, the DC voltage and the reference voltage V input from the smoothing circuit 4 to the second comparator 10
By comparing with r ₂ , it is possible to obtain an output depending on whether or not the human body is detected.

[0016]

According to the invention of claim 1, a rectangular wave is applied to an input terminal of an integrator which is formed by connecting an electrostatic capacitance whose capacitance value changes when a human body approaches it, between an inverting input terminal and an output terminal of an operational amplifier. Since the output terminal of the oscillator that outputs the voltage was connected and the input terminal of the comparator was connected to the output terminal of the integrator via the smoothing circuit, when the human body approaches and the capacitance value of the integrator becomes large, The output decreases, and as a result, the input of the comparator becomes smaller than the reference value and the output of the comparator changes, which allows the human body to be detected and does not require a reference capacitance. Therefore, there is an effect that the human body detection device can be realized with a simple configuration without the need for adjustment.

According to a second aspect of the present invention, a first comparator is provided at an output terminal of an integrator formed by connecting a capacitance whose capacitance value changes when a human body approaches, between an inverting input terminal and an output terminal of an operational amplifier. The input terminal of the first comparator is connected to the input terminal of the integrator, and the output terminal of the integrator is connected to the input terminal of the second comparator through the smoothing circuit. When the output of the first comparator is input to the integrator, the first comparator is caused to self-oscillate and a rectangular wave voltage is input to the integrator, and when the human body approaches and the capacitance value of the capacitance increases. The oscillation frequency of the first comparator becomes low, and as a result, the input of the second comparator smoothed by the smoothing circuit becomes smaller than the reference value and the output of the second comparator changes, which causes the human body to be damaged. It can be detected and requires a reference capacitance. , Yet human body detection device with an extremely simple structure that does not require oscillator there is an effect that can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic circuit configuration diagram showing a first embodiment.

FIG. 2 is a waveform diagram of output voltages of an oscillator and an integrator for explaining the above.

FIG. 3 is a schematic circuit configuration diagram showing a second embodiment.

4A and 4B are waveform diagrams of output voltages of a first comparator and an integrator for explaining the same as above. FIG. 4A is a waveform diagram when a person is not seated on the toilet seat, and FIG. It is a wave form diagram when sitting.

FIG. 5 is a schematic configuration diagram of a toilet seat using a conventional human body detection device.

FIG. 6 is a schematic circuit configuration diagram showing a conventional example.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 operational amplifier 2 integrator 3 oscillator 4 smoothing circuit 5 operational amplifier 6 comparator Cx electrostatic capacity Vr reference voltage R ₁ , R ₂ resistance C ₁ capacitor

Claims (2)

[Claims] 1. An output of an oscillator for outputting a rectangular wave voltage to an input terminal of an integrator formed by connecting a capacitance whose capacitance value changes when a human body approaches, between an inverting input terminal and an output terminal of an operational amplifier. A human body detection device characterized in that the input terminal of a comparator is connected to the output terminal of an integrator via a smoothing circuit while connecting the terminals. 2. An input terminal of a first comparator is connected to an output terminal of an integrator formed by connecting a capacitance whose capacitance value changes when a human body approaches, between an inverting input terminal and an output terminal of an operational amplifier. And a human body characterized in that the output terminal of the first comparator is connected to the input terminal of the integrator, and the output terminal of the integrator is connected to the input terminal of the second comparator through a smoothing circuit. Detection device.