JPH07104987B2 - Shutter sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention detects a magnetic field from a magnet attached to a shutter with a hall element, and generates an alarm output when the magnetic field detection output cannot be obtained when the shutter is opened. Regarding the shutter sensor.

(Prior Art) Conventionally, as a shutter sensor that detects an opening of a shutter by an intruder and outputs an alarm, a photoelectric reflection type sensor is generally used.

However, in the photoelectric reflection type shutter sensor,
There is a problem that the reflection sheet attached to the detection position of the shutter is easily torn, and false alarms are generated due to cockroaches and spiders.

Therefore, in recent years, a magnet has been attached to the shutter, and a sensor main body equipped with a magnetic field detecting means such as a reed relay or a magnetoresistive element is arranged at a position facing the magnet when the shutter is closed, and the shutter is opened in the monitoring state. When this is done, the magnetic field from the magnet is cut off, so a so-called magnetic shutter sensor has been put into practical use in which interruption of this magnetic field is detected by a reed relay or a magnetic resistance element and an alarm is output.

(Problems to be Solved by the Invention) However, such a conventional magnetic shutter sensor has a problem that the effective installation distance of the sensor main body to the magnet attached to the shutter is relatively short.

For example, a shutter sensor that uses a reed relay is about
The installation limit is 7 cm, and even with a magnetoresistive element, the installation limit is about 12 cm.

If the shutter sensor installation limit distance is short like this, the sensor installation position inside the shutter is restricted,
In the case of an existing shutter, the sensor body may not be attached unless it is located far from the shutter, and the installation work is complicated due to the use of special support metal fittings. There is a seat plate that stops the shutter from being taken up in the shutter storage part provided on the ceiling part, but this seat plate must be sufficiently larger than the entrance part of the shutter storage part. Also, it must be heavy and strong because the winding on the winding device must be stopped. For this reason, when the sensor body is attached near the shutter, the seat plate may hit and damage the sensor when the shutter is opened.

Furthermore, depending on the shutter, the shutter itself may be magnetized under the influence of a magnetic field generation source located nearby.In such a case, if the installation distance of the sensor body is short, the effect of the magnetic field of the shutter itself may occur. There was also a risk of receiving malfunctions.

(Means for Solving Problems) The present invention has been made in view of the above-mentioned conventional problems, and has a high magnetic field detection sensitivity that allows a long installation limit distance to a magnet attached to a shutter. It is intended to provide a shutter sensor.

In order to achieve this object, in the present invention, in a shutter sensor that detects a magnetic field generated from a magnet attached to a shutter, a Hall element that detects a magnetic field,
A first yoke that extends forward from a downward slight bending portion facing the front surface of the Hall element, is bent at about 90 ° midway and extends downward so as to face the magnet, and the Hall element A second downwardly extending small bent portion facing the rear surface of the second yoke, which extends rearward more largely than the first yoke, is bent at about 90 ° midway, and extends downwardly below the first yoke. And a detection circuit for generating an alarm output by detecting that the magnetic field detection output from the magnet by the Hall element is reduced or cut off.

(Operation) In the shutter sensor of the present invention having such a configuration, the magnetic fields from the magnets attached to the shutter can be efficiently provided by the magnetism collecting operation of the first and second yokes provided before and after the Hall element. They can be collected and passed through the Hall element, resulting in a critical installation distance exceeding 15 cm.

Also, since the first and second yokes are bent in the middle at about 90 ° and extend so as to face the magnet, the disconnection of the magnetic field is improved when the magnet is disengaged from the sensor installation position by opening the shutter. The detection sensitivity to the movement of the shutter can be increased.

(Embodiment) FIG. 1 is a sectional view showing an embodiment of the present invention.
The plan is shown in the figure.

In FIG. 1, reference numeral 1 denotes a sensor main body, which is installed at a predetermined distance on a ceiling surface 3 or the like inside a place where the shutter 2 is installed. The magnet 4 is attached as shown in FIG.

A circuit board 5 is incorporated in the sensor body 1, and a hall element 6 for detecting a magnetic field generated from a magnet 4 attached to the shutter 2 is provided on the circuit board 5. A first yoke 7 is arranged in front of the Hall element 6 on the side where the magnet 4 is installed, and the first yoke 7 extends from the downward slightly bent portion 7a facing the front surface of the Hall element 6 to the first bent portion 7a. As shown in the plan view of FIG. 2, it has a shape that widens toward the front. The first yoke 7 spreads forward and at the same time is bent about 90 ° in the middle to extend downward so as to face the magnet 4.

A second yoke 8 is provided behind the hall element 6.
The second yoke 8 spreads from the slightly bent downward portion 8a facing downward so as to cover the rear surface of the Hall element 6 to the rear and larger than the first yoke 7 as shown in the plan view of FIG. It has a shape that is bent at 90 ° and extends downward longer than the first yoke 7.

Further, the circuit board 5 on which the hall element 6 is mounted is provided with a detection circuit for detecting that the magnetic field from the magnet 4 due to the hall element 6 is cut off or dropped to a predetermined level or less to generate an alarm output. There is.

Next, the operation of the above embodiment will be described.

When the shutter 2 is closed, the magnet 4 attached to the shutter 2 is positioned in front of the sensor body 1 as shown in FIG. Therefore, the magnetic field from the magnet 4 toward the sensor body 1 is collected by the first yoke 7 arranged in front of the Hall element 6, and passes through the Hall element 6 to generate a magnetic field toward the second yoke 8 arranged behind. produce. That is, since the first yoke 7 has a surface facing the magnet 4 extending downward by bending about 90 ° on the way, it is generated from the magnet 4 in the range corresponding to the surface extending downward at least. The magnetic field can be collected and passed through the Hall element 6.

The magnetic field collected by the first yoke 7 that has passed through the Hall element 6 enters the second yoke 8 arranged rearward, and the second yoke 8 has a larger lateral spread than the first yoke 7. Thus, the magnetic field lines returning to the magnet 4 are dispersed in the left-right direction due to the spread, and a magnetic path returning to the magnet 4 is efficiently formed.

In the present invention, the installation limit distance of the sensor body 1 with respect to the magnet 4 attached to the shutter 2 is 15 cm or more due to the action of collecting the magnetic field generated from the magnet 4 by the first and second yokes 7 and 8 as described above. And can be long.

On the other hand, in the steady monitoring state in which the magnetic field generated from the magnet 4 is passing through the hall element 6, the detection circuit mounted on the circuit board 5 outputs the magnetic field detection output of the hall element 6 and outputs an alarm. Does not occur.

Next, if the shutter 2 is pry open by an intruder or the like in the monitoring state, the opening of the shutter 2 moves the magnet 4 upward, and the magnetic field to the sensor body 1 is cut off. Therefore, when the magnetic field detection output of the Hall element is reduced or eliminated, the detection circuit mounted on the circuit board 5 detects the shutter opening and generates an alarm output, and the buzzer or the like sounds a theft alarm.

In this way, the magnet 4 is generated by opening the shutter 2.
When the magnet 4 moves, the first yoke 7 arranged in front of the Hall element 6 is bent about 90 ° on the way and comes off from the downwardly extending surface, so that the first yoke 7 collects the magnetic field. Is significantly reduced and the magnetic field passing through the Hall element 6 is well cut off. Therefore, an alarm output can be reliably output for a slight shutter prying when the magnet 4 moves to a position deviating from the facing position of the first yoke 7. it can.

(Effects of the Invention) As described above, according to the present invention, the shutter is bent from a slight downward bent portion facing the front surface of the Hall element for detecting a magnetic field to the front and then bent at about 90 ° on the way. The first yoke extending downward so as to face the magnet attached to the magnet, and the slightly bent downward portion facing the rear surface of the Hall element, extending backward more than the first yoke. A second yoke which is bent at a degree and extends downwardly longer than the first yoke is provided, and a detection circuit is provided which detects that the magnetic field from the magnet is reduced or cut off by the Hall element and generates an alarm output. As a result, even if the strength of the magnetic field from the magnet decreases in inverse proportion to the square of the distance due to the magnetism collecting action of the first and second yokes, it is sufficient to exceed the sensor installation limit distance of 15 cm. And the distance Rukoto can, with the sensor body placed in sufficiently away from the shutter surface fitted with a magnet even existing shutter can effectively monitor the shuttering.

Specifically, by the first and second yoke shapes of the present invention,
Compared to the case where the first and second yokes are not provided, the Hall element can output approximately 20 times more power.
It has been confirmed that the magnetism collecting function of the yoke is sufficiently fulfilled.

Further, the first and second yokes arranged in front of and behind the Hall element are arranged so as to face each other with a magnet attached to the shutter.
Since it bends in the direction of ° and extends downward, when the magnet of the shutter moves to a position outside the position of this yoke extension surface, the magnetic field passing through the Hall element is cut off easily. The magnetic field detection sensitivity of can be improved.

[Brief description of drawings]

FIG. 1 is an explanatory view showing an embodiment of the present invention, and FIG. 2 is a plan view of the sensor body of FIG. 1: Sensor body 2: Shutter 3: Ceiling surface 4: Magnet 5: Circuit board 6: Hall element 7: 1st yoke 8: 2nd yoke 7a, 8a: Small bend

Claims (1)

[Claims] 1. A shutter sensor for detecting a magnetic field generated from a magnet attached to a shutter, comprising: a Hall element for detecting a magnetic field; and a front portion of the Hall element that faces a front side of the Hall element. A first yoke that expands and is bent at about 90 ° in the middle and extends downward so as to face the magnet, and a first downwardly bent portion that faces the rear surface of the Hall element, and then the first yoke extends rearward. Second yoke that is wider than the first yoke, is bent at about 90 ° midway, and extends longer than the first yoke, and the magnetic field detection output from the magnet by the Hall element is reduced or A shutter sensor, which is provided with a detection circuit that detects an interruption and generates an alarm output.