JPS5917493B2 - Object sensing and display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides an object sensing and display device, more specifically, a sensing section is provided on a door knob, etc., and has a floating communication/de/sensing capacity of more than a certain level with the ground surface of a human body, an animal, etc. The present invention relates to a device that displays an alarm or the like when an object touches or approaches a sensing part.

Conventionally, as this type of object sensing means, there are known ones that are activated by detecting an external force when an external force is directly applied, or those that are activated by optical means.

However, these devices sometimes do not operate even when an external signal is applied, and there are problems in terms of reliability, or the state of approach to the sensing section cannot be detected.

As mentioned above, the present invention provides a device that detects the contact or approach of an object to a door knob, etc., reliably outputs an alarm, and is capable of deterring thieves or accurately sorting objects. This is what we are trying to provide.

The present invention will be explained below using specific examples shown in the drawings.

FIG. 1 shows a first embodiment, in which reference numeral 1 denotes a pulse oscillator, connected to inverters 2 and 3, and fed back via a capacitor 4.

The variable resistor 5 is for changing the oscillation frequency.

The output from the pulse oscillator 1 is input to an inverter 8 forming a threshold circuit via a diode 6 and a resistor 7 connected in parallel with the diode 6.

A sensing section 9 is provided in front of the inverter 8, and corresponds to a door knob in the case of preventing a burglar as described above.

A positive potential is applied to the inverter 8, and the original potential is voltage-dropped via a light emitting diode 10 and a varistor 11 in order to save power.

For example, if the original potential is 9V, the light emitting diode 10 causes a drop of about 1.7V, and the varistor 11 causes a drop of about 2.5V.

A reverse diode 12 is connected to the output side of the inverter 8, and is further connected to an integrating circuit 13.

The integrating circuit 13 is composed of a resistor 14, a capacitor 15, and an inverter 16.

A stabilizing circuit 19 consisting of inverters 17 and 18 is connected to the next stage of the inverter 16, and the next stage of the stabilizing circuit 19 is composed of a transistor 21 whose emitter is grounded via a resistor 20 and a buzzer 22 provided on the collector side. Buzzer circuit is connected.

The operation of the device configured in this way will be explained with reference to the waveform diagram shown in FIG.
A regular rectangular wave is continuously outputted from Pl.

In the state where an object does not approach or come into contact with the sensing section 9 (Zone Z in Figure 2), the grounding capacitance (C) of the sensing section 9 is very small, and this and the resistance? (Let it be R)
Since the time constant CR of the integrating circuit is also very small, this first
A slightly distorted rectangular wave appears at the output P2 of the integrating circuit (input of the inverter 8) in synchronization with the output of the pulse oscillator 1.

Then, a thin positive pulse appears at the output P3 of the inverter 8 as a binary level output obtained by comparing the P2 waveform with the threshold level TL8.

The output P3 of this inverter 8 is converted to P3 by the second integrating circuit 13.
4, but each time the potential of the output P4 of the second integrating circuit 13 (input of the inverter 16) becomes higher than the potential of the output P3 of the inverter 8, the diode 12 becomes conductive, as shown by arrow A. Since the voltage is short-circuited through the resistor 14 and diode 12, the voltage does not rise above the threshold level of the stabilizing circuit 19.

At this time, the stabilizing circuit 19 is inactive and its output P5 remains at a low level, so the buzzer 22 does not operate and does not issue an alarm.

However, when an object (for example, a human body) having a stray capacitance above a certain level comes into contact with the sensing section 9, the output waveforms P2 to P change as shown in zone Z2.

That is, when an object comes into contact with the sensing section 9, the grounding capacitance C of the sensing section 9 increases and the time constant of CR also increases, so the output P2 of the first integrating circuit reaches the threshold level TL8 of the inverter 8. I won't be able to do that.

Therefore, the output P3 of the inverter 8 is continuously bi-level.
The output P4 of the second integrating circuit 13 also changes to the bi-level and exceeds the threshold level TL,6 of the stabilizing circuit 19.

As a result, the stabilizing circuit 19 becomes monostable and its output P5 becomes bi-level continuously, causing the buzzer 22 to continuously sound and issue an alarm.

On the other hand, if the time constants of the resistor 14 and capacitor 15 of the integrating circuit 13 are set to appropriate values, the buzzer 22 will sound intermittently when the object is close to the sensing section 9, and when the object is in contact. can be distinguished.

That is, when an object approaches the sensing section 9, the sensing section 9
The capacitance to ground increases only slightly, and the output P2 of the first integrating circuit exceeds the threshold level TL8 of the peak part inverter 8, so that the output P3 of the inverter 8
, a positive pulse whose pulse width is narrower than in zone Z2 (but wider than in zone Z1) appears in synchronization with the output P1 of pulse oscillator 1.

Therefore, a relatively bi-level signal appears intermittently at the output P4 of the second integrating circuit 13, so that the output P4 at this time
The threshold level TL6 of the level stabilizer circuit 19 of
If the time constant of the integrating circuit 13 is selected so as to exceed
The stabilizing circuit 19 is in an unstable state and outputs an intermittent signal at its output P, causing the buzzer 22 to sound intermittently.

In the above example, the buzzer 22 can of course be replaced with a display means such as a speaker or a lamp.

As described above, according to the present invention, an object can be detected by utilizing the fact that the voltage drops below the threshold level of the threshold circuit due to the approach or contact of an object with a stray capacitance greater than a predetermined value. It is reliable and has the advantage of being able to detect approaching conditions.

Therefore, it can be used not only in the disaster prevention field, but also for sorting objects in manufacturing plants, and its range of use is extremely wide.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a specific example of the present invention, and FIG. 2 is an output waveform diagram at each part thereof. 1.1'... Pulse oscillator, 8... Inverter (threshold circuit), 9... Sensing section, 13... Integrating circuit, 19... ...Stability circuit, 22...Buzzer.

Claims (1)

[Claims] 1. A first integration circuit is formed by a pulse oscillator, its own grounding capacitance that is connected to the output side of the pulse oscillator via a resistor, and changes due to contact or approach of an object with stray capacitance, and the above-mentioned resistor. and a sensing section that compares the output of the first integrating circuit with a first threshold level.
a threshold circuit that obtains a value level output; a second integration circuit that integrates the output of the threshold circuit; and a second integration circuit that compares the output of the second integration circuit with the second threshold level to detect the object in the sensing section. An object sensing and display device comprising: a stabilizing circuit that enters a monostable state when it comes into contact with an object and becomes an astable state when it approaches; and a display circuit that is driven by the output of the stabilizing circuit.