JP2005133465A - Door opening/closing detecting sensor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the detecting reliability of an oscillating type proximity switch adopted as an opening/closing detecting switch for a door and to safely protect the proximity switch from impact in closing the door. <P>SOLUTION: In this door opening/closing detecting sensor device, a detector 2a made of metal and mounted to the door 1 is placed facing a detecting surface 3a of the oscillating type proximity switch 3, and the approach of the detector is detected when the door is closed, to output a "door closing" detection signal from the proximity switch. The oscillating type proximity switch is equipped with a comparing circuit (a window comparator) 6, and an ON region where the detection signal is outputted from an output circuit 7 by sensing the approach of the detector 2a is set to a specific range spaced from the detection surface of the proximity switch. Further, the detector 2a is embedded in an outer shell body 2b formed of resin, rubber, or the like, and placed to face the detecting surface of the proximity switch, and the thickness d of the outer shell body is determined to position the detector within the range of the ON region in the closed state of the door. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a door opening / closing detection sensor device that electrically detects a door opening / closing state of a door such as a protective door and a cover attached to an equipment or the like.

For equipment and equipment that may cause accidents due to accidental contact with operating machines such as press machines, unnecessary intrusion by surrounding the machine as a security measure to ensure the safety of machine operation The door of the work entrance / exit and the maintenance / inspection door are equipped with an open / close detection switch, and the switch and the equipment are electrically interlocked. When the door opens, the output of the detection switch The operation of the machine is forcibly stopped based on the signal.
Also, a limit switch is used as a switch to detect the open / close state of the door, and the limit switch is turned on / off in response to the door open / close operation, or a magnetic proximity switch in which a reed switch is combined with a magnetic lock block A configuration in which a reed switch is turned on and off by capturing a change in magnetic flux of a magnetic circuit accompanying the opening / closing operation of the door is known (for example, see Patent Document 1).

In addition, an oscillation type proximity switch has been adopted for door opening / closing detection, and the approach of detecting the opening / closing state of the door by detecting the proximity of the metal detector attached to the door side using the oscillation type proximity switch has also been implemented. Yes. The door opening / closing detection sensor device using this oscillation type proximity switch is arranged such that the detection surface of the oscillation type proximity switch faces the metal detection body attached to the door side, and when the door is closed, the proximity switch When the proximity of the detection object is detected and a detection signal for `` door closing '' is output, the door opens and the detection object moves away from the detection surface of the proximity switch and the proximity switch stops detecting the detection object, the proximity switch The detection signal to be output is turned off.
JP-A-6-196060

By the way, the above-described conventional door opening / closing detection sensor device has the following problems in terms of function and security reliability. That is,
(1) Limit switch method: The limit switch is detected by mechanical contact between the dog attached to the door and the actuator of the limit switch, so wear powder is generated by contact between the dog and the actuator each time the door is opened or closed. In addition, since a lubricant such as grease is used for the movable mechanism of the limit switch, this lubricant may flow out of the switch, especially in the processing area and workpieces such as food machines. It is unsuitable for equipment that is extremely disliked. In addition, if the limit switch actuator is deliberately pressed even when the door is open, the switch will turn ON and the door will be mistakenly closed. In equipment that is forced to stop, there remains a problem in terms of security.

(2) Reed switch method: The contact structure of the reed switch is weak against shock and vibration, so the reed switch may malfunction due to the shock and vibration applied when the door is closed, and there is a problem in ensuring reliability. .
(3) Oscillation type proximity switch method: Oscillation type proximity switch has no moving parts like limit switch, and does not cause malfunction due to shock and vibration as seen in reed switch. Although there is an advantage that non-contact detection is possible, when a general oscillation type proximity switch is employed in the door detection sensor device, there remains a problem in the operation reliability of the door opening / closing detection as described below.
In other words, the oscillating proximity switch is based on the principle of operation. When a metal detection object approaches the detection surface of the proximity switch, an eddy current flows on the surface of the detection object due to electromagnetic induction, and the impedance of the detection coil is reduced. The oscillation voltage amplitude decreases. A general oscillation type proximity switch captures the change in the oscillation voltage amplitude and outputs an output signal. Therefore, when this oscillating proximity switch is used as a door open / close detection sensor, if a piece of metal (such as a coin) is artificially stacked on the detection surface of the proximity switch while the door is open, the proximity switch There is a problem in terms of security in the same way as the limit switch method described above, because the detection signal “door closed” is output by misidentifying that the door is closed. In addition, when the metal detection body attached to the door side collides with the detection surface of the proximity switch when the door is closed, the detection coil of the proximity switch may be damaged by the impact.

  The present invention has been made in view of the above points, and employs an oscillation proximity switch that is more reliable in detection operation than a limit switch or a reed switch. It is intended to provide an improved door open / close detection sensor device that prevents false detection of door open / close detection due to actions such as overlapping the detection surface of the door and also can safely protect the proximity switch from impact when the door is closed And

In order to achieve the above object, according to the present invention, a metal detection body attached to the door side is opposed to the detection surface of the oscillation type proximity switch, and the approach of the detection body is detected when the door is closed. In the door opening / closing detection sensor device that outputs the detection signal of “door closing” from the proximity switch,
As the detection operation characteristics of the oscillating proximity switch, the upper and lower limits of the ON area that senses the approach of a detection object attached to the door and outputs a detection signal are set to a specific range spaced from the detection surface of the proximity switch. In addition, the detection body is covered with a non-metallic outer shell so as to face the detection surface of the proximity switch, and the thickness of the outer shell is set to be within the specific range with the door closed. (Claim 1).
Here, as means for imparting the detection operation characteristic to the oscillation type proximity switch, a comparison circuit using a window comparator is provided between the oscillation circuit of the oscillation type proximity switch and the output circuit, and the output voltage of the oscillation circuit is A detection signal for “door closing” is outputted through an output circuit under a condition corresponding to a predetermined range of the ON region.

Sometimes, the outer shell covering the metal detector is made of an elastic material such as resin or rubber so as to reduce the impact force of the outer shell hitting the detection surface of the proximity switch when the door is closed. .
Furthermore, in the present invention, as means for further improving the reliability of the detection operation of the sensor device, the oscillation proximity switch is provided with a plurality of detection coils, and a specific range of the ON region is separately set for each detection coil. In addition, a plurality of metal detectors individually corresponding to each of the detection coils are arranged on the door side, and each detector is arranged at a position corresponding to a specific range of the ON region of the corresponding detection coil, and the door is When closing, a detection signal of “door closing” is output under the condition that each detection body is located in each ON region.

According to the door opening / closing detection sensor device having the above-described configuration, the following effects can be obtained.
(1) Since it uses an oscillation type proximity switch to detect the open / closed state of the door without contact, wear due to mechanical contact between the dog and actuator, which has been a problem with conventional devices that employ limit switches and reed switches There is no risk of generation of powder, foreign matter such as lubricant, and malfunction of the reed switch due to impact or vibration.
(2) By setting the ON area of the oscillating proximity switch to a specific range spaced from the detection surface of the proximity switch, a metal piece such as a coin is deliberately placed in the proximity switch detection surface (this Even if the range is applied to the OFF region (detection dead zone) outside the ON region, the detection signal is not output from the proximity switch. As a result, the door is not mistakenly closed, and high safety can be ensured with respect to the operation of the equipment that is interlocked with the proximity switch.

The metal detector attached to the door side is covered with an elastic outer shell such as resin or rubber so as to face the proximity switch, so that the metal detector detects the proximity switch when the door is closed. Since the outer shell body does not directly hit the surface and the impact force is buffered, the switch can be prevented from being damaged.
(3) In addition, multiple sets of oscillation proximity switch detection coils and metal detectors are provided, and the range of the ON region is set for each detection coil, and the detection body is specified for the ON region of each detection coil. According to the configuration of claim 4, which is arranged at a position matching the range and covered with an outer shell, security against fraudulent acts that erroneously operate a proximity switch in which a metal piece is intentionally brought close to the detection surface of the proximity switch. The sex can be further enhanced.

  Hereinafter, embodiments of the present invention will be described with reference to the illustrated examples.

FIG. 1 (a) is a block diagram of a door opening / closing detection sensor device, wherein 1 is a door to be detected attached to an equipment machine or the like (not shown), 2 is a detection unit attached to the door, and 3 is a detection unit 2 This is an oscillating proximity switch placed inside the door entrance opposite to the door. Here, the detection body unit 2 has a structure in which a detection body 2a made of a metal plate is embedded in an outer shell 2b made of an elastic material such as resin or rubber, and is fixed to the inner surface of the door 1. On the other hand, the oscillating proximity switch 3 includes an oscillation circuit including a detection coil 4 disposed on the front end detection surface of the switch, a comparison circuit 6 for setting an ON region described later, and an output circuit 7, and the door 1 is closed. At this time, the detection body 2 a is detected, and a detection signal of “door closing” is output to the outside through the output circuit 7.
FIG. 1B is a detection operation characteristic diagram of the oscillation type proximity switch 3. That is, when the metal detection body 2a is far away from the detection surface 3a of the oscillation type proximity switch 3 (in a state where the door is open), the detection coil 4 impedance is large and the oscillation voltage amplitude is large, and the door is closed. When the detection body 2a approaches the detection surface 3a of the oscillation type proximity switch 3, an eddy current flows on the surface of the detection body due to the linkage with the alternating magnetic field of the detection coil 4, and the impedance of the detection coil is lowered to reduce the oscillation voltage. The amplitude becomes smaller. As a result, the output voltage characteristic of the oscillation circuit 5 that smoothes the oscillation voltage of the detection coil 4 is high when the detection body 2a is away from the detection surface 3a of the proximity switch as shown in the figure, and decreases when approaching.

With respect to this oscillation circuit output voltage characteristic, in the oscillation type proximity switch 3 of the embodiment, an ON region in which a detection signal is output through the output circuit 7 by the comparison circuit 6 provided at the subsequent stage of the oscillation circuit 5 is shaded as shown in the figure. The detection operation characteristic is set so that the detection signal is not output in the other OFF region. In the illustrated example, the ON region is set in a range in which the oscillation circuit output voltage V1 is the lower ON voltage lower limit and V2 is the upper ON voltage upper limit, and the corresponding distance L1 from the detection surface 3a of the proximity switch to the detection body 2a is ON. With the distance lower limit and L2 being the ON distance upper limit, the detection signal is output under the condition that the detection body 2a is located in the range of the ON region.
Further, the outer shell 2b of the detection unit 2 in which the detection body 2a is embedded in accordance with the setting of the ON region is the detection surface 3a of the oscillation proximity switch 3 at the position where the door 1 is closed as shown in FIG. In this state, the thickness d is determined so that the distance between the detection body 2a and the detection surface 3a is located in the ON region between the ON distance lower limit L1 and the ON distance upper limit L2.

Next, a detailed circuit of the oscillation proximity switch 3 will be described with reference to FIG. 2, and a timing chart of the operation will be described with reference to FIG. In FIG. 2, the comparator circuit 6 has a circuit configuration known as a window comparator, and has two comparators OP1, OP2 having different thresholds, an input resistor R1, and reference voltage dividing resistors R2-R5 corresponding to the comparators OP1, OP2. And output resistors R6 and R7. The output circuit 7 connected to the subsequent stage of the comparison circuit 6 comprises a level shift Zener diode ZD1, an output transistor Q1, a surge protection Zener diode ZD2, and a base resistance R8 of the output transistor Q1. Reference numeral 8 denotes a power supply circuit (power supply voltage Vcc), and 9 denotes a load of a detection signal output from the oscillation proximity switch 3 (such as a “door closed” indicator).
When the door 1 is opened and closed in a state where the oscillation type proximity switch 3 is employed to monitor the open / closed state of the door 1, the metal detector 2a is detected from the detection surface 3a of the proximity switch 3 (see FIG. 1A). The output voltage of the oscillation circuit 5 (the voltage at the point P1 in FIG. 2) varies as shown by the oscillation circuit output voltage characteristics of FIG.

Further, the ON voltage upper limit V2 in the ON region shown in FIG. 1B is a voltage determined by the voltage dividing ratio between the voltage dividing resistors R2 and R3: Vcc × R3 / (R2 + R3), and the ON voltage lower limit V1 is The voltage determined by the voltage dividing ratio between the piezoresistors R4 and R5 is Vcc × R5 / (R4 + R5).
If the output voltage of the oscillation circuit 5 is in the range between the upper limit voltage V2 and the lower limit voltage V1 (ON region in FIG. 1 (b)), the output voltage of the comparison circuit 6 (at the point P2 in FIG. 2). Voltage) becomes an H level corresponding to the power supply voltage Vcc, and a current flows to the base of the output transistor Q1 through the Zener diode ZD1 of the output circuit 7, whereby the output transistor Q1 is turned on and the load 9 is turned on. Closed is detected.
On the other hand, when the output voltage of the oscillation circuit 5 is higher than the upper limit voltage V2, the output voltage of the comparison circuit 6 is Vcc × R6 (R6 + R7), and when lower than the lower limit voltage V1, The output voltage is Vcc × R7 (R6 + R7). Here, assuming that the breakdown voltage of the Zener diode ZD1 is Vz1, Vcc.times.R6 (R6 + R7) <Vz1, Vcc.times.R7 (R6 + R7) <Vz1, so that the output resistances R6, R7 of the comparators OP1, OP2 and the Zener diode ZD1. If the output voltage of the oscillation circuit 5 is higher than the upper limit voltage V2 or lower than the lower limit voltage V1, the output transistor Q1 remains non-conductive. No detection signal is output from the oscillation proximity switch 3.

As a result, the detection operation characteristic of the oscillation proximity switch 3 has the ON region and the OFF region in FIG. 1B, and the oscillation proximity switch 3 in the state of FIG. The detection signal “door closed” is output. Further, the outer shell 2a of the detection unit 2 attached to the door 1 is made of an elastic body such as resin or rubber so that the detection unit 2 collides with the detection surface 3a of the oscillation proximity switch 3 when the door 1 is closed. Even in this case, the outer shell 2a serves as a buffer to prevent the proximity switch from failing.
Therefore, even if the metal piece such as a coin is intentionally applied to the detection surface 3a of the oscillation proximity switch 3 (OFF region in FIG. 1B) with the door 1 open, the oscillation proximity switch Since the detection signal is not output, there is no possibility of misidentifying that the door is closed, so that the safety of the operation of the equipment interlocked with the oscillation proximity switch 3 can be ensured.

  Even if the detection coil 4 is disconnected due to an object hitting the oscillating proximity switch 3 or the like, if the detection coil 4 is disconnected, the impedance of the coil increases and the output voltage of the output circuit 5 becomes higher than that described above. Since the ON voltage upper limit V2 is exceeded, the switch output is OFF. When the detection coil 4 causes a short-circuit accident, the impedance of the coil becomes smaller and the output voltage of the output circuit 5 becomes lower than the ON voltage lower limit V1. And fail safe can be secured.

  Next, as an application example of the first embodiment, an embodiment corresponding to claim 4 of the present invention is shown in FIG. In this embodiment, the oscillation proximity switch 3 is provided with two sets of detection coils 4a and 4b, and a comparison circuit 6 is connected to each oscillation circuit of each detection coil so that the ON region (see FIG. 1 (b)). The specific range is changed to a different range and set separately, and the output of each comparison circuit 6 is input to the output circuit 7 via the AND circuit 10. The coil unit 2 mounted on the door side facing the detection surface of the oscillation proximity switch 3 has two metal detectors 2a-1 and 2a-2 corresponding to the detection coils 4a and 4b, respectively. Are embedded in the outer shell 2b, and the detectors 2a-1 and 2a-2 are arranged at positions corresponding to a specific range of the ON region of the detection coil corresponding to the detection. Then, when the door is closed, a detection signal “door closed” is output through the output circuit 7 under the condition that each of the detection bodies 2a-1 and 2a-2 is located in a range corresponding to the ON region. Like to do.

  According to this configuration, since the two metal detectors 2a-1 and 2a-2 embedded in the outer shell 2b of the detection unit 2 are arranged at different positions in the front-rear direction, it is possible to detect the opening / closing of the door. Reliability can be further increased.

BRIEF DESCRIPTION OF THE DRAWINGS It is explanatory drawing of a structure and detection operation | movement of a door opening / closing detection sensor apparatus corresponding to Example 1 of this invention, (a) is a schematic block diagram of a sensor apparatus, (b) is an oscillation type proximity switch in (a) figure. Detecting operation characteristic diagram showing the relationship between oscillation circuit output voltage and ON / OFF area of detection signal Detailed circuit diagram of the oscillation type proximity switch in FIG. Timing chart showing the detection operation of FIG. Schematic configuration diagram of a door opening / closing detection sensor device corresponding to Example 2 of the present invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Door 2 Detection unit 2a, 2a-1, 2a-2 Detection body 2b Outer shell body 3 Oscillation type proximity switch 3a Detection surface 4 Detection coil 5 Oscillation circuit 6 Comparison circuit 7 Output circuit

Claims (4)

It is a door open / close detection sensor device that detects the open / closed state of a door using an oscillating proximity switch, and when a metal detector attached to the door is opposed to the detection surface of the oscillating proximity switch and the door is closed In what detects the approach of the detection body and outputs a detection signal of "door closing" from the proximity switch,
In the oscillation proximity switch, as a detection operation characteristic, an ON region that senses the approach of the detection body and outputs a detection signal is set to a specific range separated from the detection surface of the proximity switch, and the detection body attached to the door side The outer shell is covered with a non-metallic outer shell so that it faces the detection surface of the proximity switch, and the thickness of the outer shell is determined so that the detector is positioned within the specific range with the door closed. A door opening / closing detection sensor device. 2. The sensor device according to claim 1, further comprising a comparison circuit using a window comparator between the oscillation circuit and the output circuit of the oscillation type proximity switch, wherein the output voltage of the oscillation circuit corresponds to a predetermined range in the ON region. The door opening / closing detection sensor device is characterized in that a detection signal is output via an output circuit under the conditions of 2. The door opening / closing detection sensor device according to claim 1, wherein the buffer shell covering the detection body is made of an elastic material such as resin or rubber. 2. The sensor device according to claim 1, wherein the oscillating proximity switch includes a plurality of detection coils, and a specific range of the ON region is separately set for each detection coil. A door opening / closing detection sensor device comprising: a plurality of metal detectors corresponding to each of the detectors, and each detector being disposed at a position corresponding to a specific range of an ON region of a detection coil corresponding to the detector.

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