JPS5948355B2 - proximity detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device that detects an object by a change in capacitance.

Proximity detection devices are attached to the front edge of doors in elevators, etc., and detect people or obstacles in the path of the door without contact when the door is closed or fully opened, and can detect people or obstacles in the path of the door when the door is closed or fully opened. It is used to stop.

This type of proximity detection device is constructed as shown in FIG.

In Figure 1, 1 and 2 are antennas that are separated and attached to the front edge of the door, 3 is a shroud that is insulated from the antennas 1 and 2, 4 is an antenna cover that protects the antennas 1 and 2, and 5
, 6 are the capacitances between the antenna 1°2 and the door plate 3, 7 and 8 are the capacitances that the antennas 1 and 2 have with the ground, respectively, and 9 is the AC power supply, and the capacitance 5 is .about.8 form an AC bridge, and are normally set so that capacitance 5×capacitance 8=capacitance 6×capacitance 7.

10 is an AC amplifier circuit, 11 is a rectifier circuit, 11a is its output, 12 is a DC amplifier circuit, 12a is its output, 13
is an output relay, 13a is its output, 14 is an AC amplifier circuit, 14a is its output, 15 is a rectifier circuit, and 15a is its output.

Normally, the AC bridge is balanced, there is no voltage between the antennas 1 and 2, and the output 11 of the rectifier circuit 11
a is zero.

However, the capacitances 7 and 8 between the antenna and the ground change due to dust adhesion to the antenna cover 4 and changes in the surrounding environment such as temperature and humidity.

Therefore, the AC bridge becomes unbalanced, and the output 11
An output corresponding to the degree of unbalance appears at a.

In order to avoid the influence of unbalance of the AC bridging caused by the above-mentioned surrounding environment, in the DC amplifier circuit 12, the output 11 of the rectifier circuit 11
a is amplified, and the output relay 13 is driven only when there is a large unbalance in the AC bridge, that is, when the antenna cover 4 is touched with a hand.

On the other hand, the AC amplifier circuit 14 selectively amplifies the change in the output 11a of the rectifier circuit 11 in order to avoid the influence of unbalance due to the surrounding environment of the AC bridge. The approach of the person is detected with high sensitivity and the output relay 13 is driven.

The output relay 13 prevents the door of an elevator or the like from closing, stops and reverses the door while it is closed, and prevents people from getting caught in the door.

However, in the above-mentioned proximity detection device, when a person touches the antenna cover 4, continues touching the antenna cover 4, and then releases the hand from the antenna cover 4, the movement of the hand and the operation of the output relay 15 occur. A problem occurs where a discrepancy appears.

This problem will be explained using FIG. 2.

At time t1, when a person touches the antenna cover 4 of the antenna 1 part, the capacitance 7 of the antenna 1 increases, and the output 11a of the rectifier circuit 11 corresponds to the degree of increase.
changes.

The DC amplifier circuit 12 amplifies the output 11a of the rectifier circuit 11, and drives the output relay 13 when the output 12a is greater than a preset voltage level Va.

At the same time, the AC amplifier circuit 14 selectively amplifies the change in the output 11a of the rectifier circuit 11, full-wave rectification is performed in the rectifier circuit 15, and when the output 15a is greater than a preset voltage level vb, the output relay 13 is driven. do.

While touching the antenna cover 4 with the hand and continuing to touch the antenna cover 4, the movement of the hand with respect to the antenna cover 4 and the movement of the output relay 13 match.

However, at time t2, when the antenna cover 4 is released, the AC amplifier circuit 14 emits an output 14a with the opposite polarity to the previous one, and the output relay 13 operates at time T, and becomes inactive at time t3.

That is, the movement of the hand and the movement of the output relay 13 no longer match.

As a result, the following problems occur.

(a) When the door is fully open and you touch the antenna cover 4 to prevent the door from closing, even if you release your hand from the antenna cover 4, the door will not close immediately, and as shown in Figure 2. Since the elevator begins to close after the indicated time T, the operating efficiency of elevators and the like decreases.

(b) A door closing device that controls so that if you touch the antenna cover 4 while the door is closing, the door opens only while your hand is touching it, and the door closes immediately when you release your hand. In this case, if an attempt is made to prevent the door from closing by touching the antenna cover 4, the door opens more than necessary, and the operating efficiency decreases as in the case of -G.

SUMMARY OF THE INVENTION The object of the present invention is to improve the above-mentioned drawbacks, and to provide a proximity detection device that immediately closes the door when an obstacle leaves the door.

An embodiment of the present invention will be described below with reference to FIGS. 3 and 4.

In FIG. 3, 20 and 21 are rectifier circuits that convert the AC voltage appearing at the antenna 1.2 into DC voltage, respectively; 20a;
21a are the outputs of the rectifier circuits 20 and 21, respectively.

The outputs 20a and 21a of the rectifier circuits 20 and 21 are in the form of converting the ground capacitances 7 and 8 of the antennas 1 and 2, respectively, into DC voltages, and when the antenna 1 and a person approach, the ground capacitance 7 increases, The voltage appearing on the antenna 1 changes, and the output 20a of the rectifier circuit 20 changes.

Similarly, when the antenna 2 and a person come close to each other, the output 21a of the rectifier circuit 21 changes.

22 is a first detection circuit, which detects a person approaching the antennas 1 and 2 without contact; 22a is its output; 23 is a differential amplifier circuit; 23a is its output; 24 is an AC amplifier circuit. , 24a is its output, 25 is a rectifier circuit, 25a is its output, 26 is a voltage comparator, 27 is a reference voltage control circuit, and 27a is its output.

In the differential amplifier circuit 23 in the first detection circuit 22, the respective outputs 20a of the rectifier circuits 20.21.

21a is amplified.

The capacitances 5 and 6 and the ground capacitances 7 and 8 seen from the output of the differential amplifier circuit 23 constitute a bridge,
[Capacitance 5] x [Capacitance 8] - [Capacitance 6] x [
When the capacitance 7] is satisfied, the output 23a of the differential amplifier circuit 23 becomes zero.

When a person approaches antenna 1, the ground capacitance of antenna 1 increases
If the setting is made such that the output 23a of the differential amplifier circuit 23 changes in the positive direction when

Normally, the capacitances 5 and 6 and the ground capacitances 7 and 8 are adjusted so that the output 23a of the differential amplifier circuit 23 becomes zero, but due to changes in ambient temperature, humidity, etc., or changes to the antenna cover 4. Due to the adhesion of dust, etc., it becomes difficult to maintain a balance between capacitances 5 to 8 at all times.

Therefore, the output 23a of the differential amplifier circuit 23 is not always zero, but fluctuates.

Generally, the output 2 of the differential amplifier circuit 23 due to this ambient condition
3a has a longer period than the change in the output 23a of the differential amplifier circuit 23 when a person approaches the antennas 1 and 2. Only the change in is transmitted to the next stage AC amplifier circuit 24.
This selectively amplifies the signal and removes the influence of ambient conditions.

Since the polarity of the output 24a of the AC amplifier circuit 24 is different when a person approaches the antenna 1 and when a person approaches the antenna 2, the output 24a is full-wave rectified by the rectifier circuit 25 in the next stage, and then output by the voltage comparator 26. When the output 25a of the rectifier circuit 25 exceeds the preset output 27a of the reference voltage control circuit 27, the output 22a of the first detection circuit 22 is generated as a detection signal.

28 is a second detection circuit, which detects a person touching the antenna cover 4, 28a is its output, 29 is a summation amplifier circuit, 29a is its output, 30 is an AC amplifier circuit,
30a is its output, 31°32 is a voltage comparator, 31a
, 32a are their outputs, and 33 is a pulse counter.

In the summation amplifier circuit 29 of the second detection circuit 28, the output 20a obtained by the rectifier circuit 20.21.

21a is added and amplified.

If the output 29a of the summation amplifier circuit 29 is set to decrease due to an increase in the ground capacitance 7, 8 of the antenna 1 or 2, then Output 29a of summation amplifier circuit 29
increases.

In this way, as seen from the output 29a of the summation amplifier circuit 29,
The divided antennas 1 and 2 are equivalent to configuring one antenna.

In such a single antenna configuration, the ground capacitances 7 and 8 of the antennas 1 and 2 are susceptible to changes due to vibrations of the door during closing operation, ambient temperature, humidity, etc., and the harmonic amplifier circuit 2
9's output 29a fluctuates.

Therefore, it is difficult to detect changes in the ground capacitances 7 and 8 of the antennas 1 and 2 with high sensitivity from the output 29a of the summation amplifier circuit 29.

Therefore, in the second detection circuit 28, the antennas 1 and 2
Only a large change in the ground capacitance of 7°8, that is, an action of touching or releasing the antenna cover 4, is detected.

When there is a large change in the output 29a of the harmonic amplification circuit 29, if this change is selectively amplified by the AC amplification circuit 30, when there is an action such as touching the antenna cover 4,
When there is an action such as letting go of the antenna cover 4, the polarity of the output 30a of the AC amplifier circuit 30 is different.

In the voltage comparator 31, the output 30 of the AC amplifier circuit 30
It discriminates the polarity and size of a, and when there is an action of touching the antenna cover 4, an output 31a of the voltage comparator 31 is generated, and when there is an action of removing the hand from the antenna cover 4, an output of the voltage comparator 32 is generated. 32a.

The content of the pulse counter 33 is normally set to zero, and the pulse counter 33 is counted up by the output 31a of the voltage comparator 31, that is, by the action of touching the antenna cover 4. Things are remembered.

Then, a signal indicating that the antenna cover 4 is being touched is generated as the output 28a of the second detection circuit 28.

The pulse counter 33 is counted down by the output 32a of the voltage comparator 32, that is, by the action of removing the hand from the antenna cover 4, the memory of the action of touching the antenna cover 4 is erased, and the second The output 28a of the detection circuit 28 also disappears.

When there are multiple tentacles on the antenna cover 4, the output 28a of the second detection circuit 28 is generated until there are the same number of tentacles.

The reference voltage control circuit 27 connects the detection signal output 28a of the second detection circuit 28 to the voltage comparator 26 of the first detection circuit 22.
This is a circuit that sets the reference voltage of

34 is an Or (circuit), and 13 is an output relay.

Output 22a of first detection circuit 22 and second detection circuit 28
The output 28a drives the output relay 13 through the OR circuit 34.

In the embodiment shown in FIG. 3, the operation when the hand continues to touch the antenna cover 4 and then releases the hand from the antenna cover 4 will be described with reference to FIG.

The output 27a of the reference voltage control circuit 27 is normally low when the output 28a of the second detection circuit 28 is absent! Pressing bell■1
is maintained.

When the part of the antenna cover 4 corresponding to the antenna 1 is touched, the output 2 of the rectifier circuit 25 of the first detection circuit 22
5a, a positive pulse is generated, which is the reference voltage control circuit 27.
When the output 27a of the first detection circuit 22 becomes larger than the output 27a of the first detection circuit 22, the output 22a of the first detection circuit 22 is generated.

At the same time, a negative pulse is generated at the output 30a of the AC amplifier circuit 30 of the second detection circuit 28, and when the reference voltage becomes -H in the voltage comparator 31, it is detected that the antenna cover 4 has been touched. The second detection circuit 28 generates an output 31a, counts up the pulse counter 33, and generates an output 28a from the second detection circuit 28.

The output 27a of the reference voltage control circuit 27 is set to the previous level ■1 by the output 28a of the second detection circuit 28.
Changes to a higher level v4.

If the antenna cover 4 continues to be touched, the output 27a of the reference voltage control circuit 27 continues to maintain the high level (4) due to the output 28a of the second detection circuit 28.

Next, when you release your hand from the antenna cover 4, a positive pulse is generated at the output 30a of the AC amplifier circuit 30 of the second detection circuit 28, and when the voltage becomes higher than the set voltage v3 of the voltage comparator 32, The output 32a is generated as a signal that the hand is released from the antenna cover 4, the pulse counter 33 is counted down, and when the content reaches zero, the second detection circuit 2
8's output 28a disappears.

At this time, the output 27a of the reference voltage control circuit 27 is at a high voltage level, and a positive pulse is generated at the output 25a of the rectifier circuit 25 of the first detection circuit 22, causing a gradual change from the high voltage level V4 to the low voltage level V1. , reference voltage control circuit 27
The voltage comparator 26 does not operate, and the output 22a of the first detection circuit 22 is no longer generated.

That is, when the user takes his hand off the antenna cover 4, the detection sensitivity of the first detection circuit 22 is made relatively low.

As a result of the above operation, the output relay 13 operates from time t□ to time t2, which coincides with the hand movement, and after touching the antenna cover 4 and blocking the door closing operation +g-, the hand moves from the antenna cover 4. When released, the door can be immediately closed.

- In the embodiment described in F, the output 28a of the second detection circuit 28 detects that the antenna cover 4 is touched by a hand.
When the output 27a of the reference voltage control circuit 27 is changed and the antenna cover 4 is released, the first detection circuit 22
Although the detection sensitivity was lowered, it is clear that equivalent results can be obtained by other examples described below.

(Force) The output 28a of the second detection circuit 28 changes the amplification degree of the amplifier circuit of the first detection circuit 22, thereby lowering the detection sensitivity of the first detection circuit 22 when the hand is removed from the antenna cover 4.

(a) Biasing the output 25a of the rectifier circuit 25 of the first detection circuit 22 by the output 28a of the second detection circuit 28 increases the detection sensitivity of the first detection circuit 22 when the hand is removed from the antenna cover 4. make low.

(1) A detection body including antennas 1 and 2, a shield plate 3, an antenna cover 4, etc. is movably attached to the tip of the door, and a switch attached to the detection body or the door pushes the detection body. In a proximity detector structured such that it is activated by this, the reference voltage control circuit 27 is activated by the signal from the switch.

Further, the amplification degree of the amplifier circuit of the first detection circuit 22 may be changed by the signal from the switch, and the output 2 of the rectifier circuit 25 of the first detection circuit 22 may be changed by the signal from the switch.
A bias voltage may be applied to 5a.

(1) Output 20a of the AC amplifier circuit 20 of the second detection circuit 28 that occurs when the hand is removed from the antenna cover 4 or output 32a of the voltage comparator 32 that detects that the hand is removed from the antenna cover 4 Using the reference voltage control circuit 2
Operate 7.

Further, the amplification degree of the amplifier circuit of the first detection circuit 22 may be changed using the output 30a or the output 32a, and the output of the rectifier circuit 25 of the first detection circuit 22 may be changed using the output 30a or the output 32a. A bias voltage may be applied to 25a.

g) The detection sensitivity of the first detection circuit 22 is gradually changed from when the hand is removed from the antenna cover 4;
There is a time delay from when the hand is released from the antenna cover 4, and the state of no detection sensitivity or the state of low detection sensitivity is changed stepwise to the state of the original detection sensitivity.

As explained above, the present invention detects an object whose value corresponding to the change in the ground capacitance of the antenna exceeds a reference value, and detects an object approaching the door or moving away from the door. It detects whether the object has touched the door or left the door, and the above reference value is increased immediately after the object leaves the door, so the object detection sensitivity decreases immediately after the object leaves the door. It becomes possible to close the door as soon as the object that was blocking the door closing operation leaves, reducing the dead time that occurs during door operation.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram of a conventional proximity detection device, FIG. 2 is an output waveform diagram of each part of FIG. 1, FIG. 3 is a block circuit diagram showing an embodiment of the proximity detection device according to the present invention, and FIG. The figure is an output waveform diagram of each part in FIG. 3. 1.2...Antenna, 3...Shipping plate, 4...Antenna cover, 5, 6...Between antennas 1 and 2 and binding plate 3 The capacitance of 7, 8...
... Ground capacitance of antenna 1.2, 9...
... AC power supply, 13 ... Output relay, 20
．． 21... Rectifier circuit, 22... First detection circuit, 23... Differential amplifier circuit, 24...
... AC amplifier circuit, 25 ... Rectifier circuit, 26
...Voltage comparator, 27...Reference voltage control circuit, 28...Second detection circuit, 29...
... Harmonic amplification circuit, 30 ... AC amplification circuit,
31.32... Voltage comparator, 33...
Pulse count, 34...OR circuit. Note that the same parts in the figures are indicated by the same reference numerals.

Claims (1)

[Claims] 1 A pair of antennas arranged at intervals from each other are arranged along the front edge of the door, and when the value corresponding to the change in the ground capacitance of the antenna exceeds a reference value, the door is closed. a first detection circuit for detecting an object approaching or leaving the door; and detecting a change greater than the change in ground capacitance and generating an output when the object contacts the door; A second detection circuit whose output is no longer output when the user leaves the door is provided, and the movement of the door is controlled by the outputs of the first and second detection circuits. A proximity detection device comprising means for increasing the reference value set in the first detection circuit.