JPS63191300A - Preventor for theft or the like - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a device for preventing theft, etc.

[Conventional technology]

Conventionally, magnet/reed switch type sensors and microswitch type sensors shown in FIG. 6(2), υ have been used as sensors for anti-theft devices.

Among these, in a magnet/reed switch type sensor, for example, a magnet is attached to an object to be prevented from theft, and a reed switch is placed separately in close proximity to the magnet, and the object to be prevented from theft having the magnet is moved and separated from the reed switch. When it is, the reed switch turns 0FF (in the case of a contact)
, or 0N (in the case of a b contact).

In addition, in the microswitch type sensor, the actuating piece is kept in contact with the target object, and the actuating piece is removed from the target object as the target object moves, making use of the fact that the actuating piece moves 0N10FF7.

[Problem to be solved by the invention]

As described above, in the sensors used in conventional theft prevention devices, the difference between normal operation and abnormality detection is simply due to the rM closing of the circuit.

For this reason, either short-circuit (directly connect) the wiring (connection line) to the sensor, which is the detection end, and then disconnect it (A contact type).
Or, if it was simply disconnected (b contact type), it could not be detected on the main body side, and there were many cases where it could not perform its intended function.

Therefore, the present invention improves the shortcomings of the conventional device as described above, and improves the reliability of the device by short-circuiting the wire to the sensor and then disconnecting it, or by directly disconnecting it to accurately detect abnormal situations. The purpose is to provide a highly anti-theft device.

[Means for solving problems]

According to the theft prevention device according to the present invention, the sensor unit 1 includes a circuit in which a resistor RS of a predetermined value is connected in series to a switching element 5 that opens upon detection of movement of an object to be prevented from theft or the like.
A predetermined reference voltage range including a voltage value generated based on the current flowing through the resistor R3 when the switching element 5 is closed is set, and a command signal is issued when the voltage value deviates from the reference voltage range. Discrimination unit 2 to output
It is characterized in that it is provided with: and an alarm section 3 that notifies an abnormality by the command signal.

[Effect]

When an object to be prevented from theft or the like moves from the sensor section 1, the switching element 5 of the sensor section 1 opens, and when the circuit is closed, the resistor R
Since the predetermined voltage value generated at 8 becomes "0°" and is out of the reference voltage range of the discriminating section 2, a command signal is output from the discriminating section 2, thereby causing the alarm section 3 to notify the abnormality.

〔Example〕

Hereinafter, illustrated embodiments of the invention will be described.

FIG. 1 is a circuit diagram showing one embodiment of the overall configuration of the present invention.

The theft prevention device according to the present invention includes a sensor section 1, a discrimination section 2, and an alarm section 3. The sensor unit 1 has a reed switch 5 that is opened and closed by a magnet 4 attached to, for example, a product to be anti-theft, and a resistor R8 having a predetermined value is connected in series to the reed switch 5.

Therefore, if the magnet 4 is located close to the sensor section 1, the reed switch 5 will be biased to close the switch terminals by the lines of magnetic force of the magnet 4 (in the case of a contact), and the output terminal of the sensor section 1 will be biased to close the switch terminals. The internal resistance value seen from is the value of resistor R3 (the contact resistance etc. of reed switch 5 is R
It is assumed that the value is negligible compared to the value of 3).

The discrimination section 2 provided at the next stage of the sensor section 1 is composed of a window comparator 6 and four resistors R, R2, R3, and R4. Of these, resistors -R, R3, and R4 are connected in series between a positive potential of 10 VcC and a ground potential, and the voltage at the connection point of resistors R and R3 and the connection point of R3 and R is ``vre''.
rH and vrert are input to the window comparator 6 as an upper limit reference voltage value and a lower limit reference voltage value, respectively.

These upper and lower limit reference voltage values are given separately, and by appropriately selecting each resistance value, the upper and lower limit reference voltage values of the window comparator 6 can be arbitrarily set.

In addition, a resistor R3 and a resistor R1 built in the sensor unit 1 are connected in series between a positive potential of 10cc and a ground potential, and a voltage is input to a partial voltage comparator 6 at the connection point of these resistors R and R1. be done.

This window comparator 6 has two comparators io, 1
i and an AND gate 12 that performs an AND operation on these outputs, one of the comparators 10 has a non-inverting input inputted with a reference voltage value vrert+, and an inverted input inputted with a divided voltage value Vio. .

Therefore, as shown in Fig. 3 (2) and (v), the comparator 1
0, the input voltage (divided voltage m>v, n is base Q, voltage v
The output becomes high level only when it is lower than refH.

Regarding the other comparator 11 constituting the land comparator 6, the input voltage ■io is input to the non-inverting input, and the reference voltage ■refL is applied to the inverting input. Then, the bell in Figure 4 (2) and (c) yelled.

Therefore, A of the two outputs of these comparators 10.11
As shown in FIG. 5(2), 0, the window comparator 6 which takes the ND calculation value has an input voltage Vio equal to the reference voltage v.
Reference voltage V below rO□. When the value is 75 or more, the output becomes high level.

Therefore, from the window comparator 6, vrerL
The high level signal in the range <vin<vreftl is v
When in is out of this range, a low level signal is output to the alarm section 3 connected to the next stage.

This alarm section 3 includes a latch circuit 7, an oscillator 8 and a speaker 9.
is configured, and when a low level signal is input from the discriminator 2, the latch circuit 7 operates to hold the signal for a predetermined period of time. The oscillator 8 emits a low frequency signal while the latch circuit 7 is operating, and the speaker 9 emits an alarm sound.

In the above configuration, when the magnet 4 is normally located close to the sensor section 1, the reed switch 5
is closed, and the window comparator 6 of the discriminator 2 receives vio divided by the resistors R and R4. At this time, vio is the preset vrofull and vref.
Since it is within the range of L, the discriminator 2 does not operate (V
>V・>V).

re4tl +n refL On the other hand, if the magnet 4 separates from the sensor section 1 in the event of an abnormality and the reed switch 5 is opened or disconnected, the resistance value inside the sensor section 1 becomes infinite and becomes v in""o. Become. For this reason, vio deviates from the standard value (V・
<■), the window comparator+n rerL controller 6 operates, and the alarm unit 3 generates an alarm.

Furthermore, if an attempt is made to disconnect or remove the sensor section 1 after short-circuiting the wiring between the sensor section 1 and the discrimination section 2, the total voltage of +vcc becomes Vi at the time of the short-circuit.

The signal is input to the window comparator 6 as follows.

Therefore, VintfiVrefH is exceeded (V
,.

〉■　　　), window comparator 6 is activated and e4H An alarm is issued from the alarm unit 3.

In this way, since the partial pressure value corresponding to the value of the implant R8 installed in series in the sensor section 1 is monitored and compared with the reference voltage range of a certain setting j width, the reed switch 5 of the sensor II is If the value of the resistor R3 deviates from the reference value due to an open circuit, a short-circuit and then disconnection of the σ wire to the sensor section 1, or a direct disconnection, the y normal state is immediately detected.

In this embodiment, a magnet/reed switch type sensor is used as the sensor section 1, but the same function can be achieved by connecting a resistor R8 in series to the micro switch 10 as shown in the second section. 1 is over.

Further, the device constructed in this way is not limited to a device for preventing damage to products, etc., but can also be used as an intrusion prevention device by being attached to an opening/closing part such as a door or window.

〔Effect of the invention〕

According to this invention, not only when an object to be prevented from theft, etc. is taken away directly, but also when the wiring to the sensor is quickly cut by short-circuiting it, or even if it is cut by a weld, the abnormality is accurately detected. It is possible to grasp the situation and provide a device for preventing theft, etc., which is highly effective for borrowing money.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, Part 2)
The figure is a configuration diagram showing another embodiment of the sensor section, Fig. 3 (2)
, (f), Fig. 4 (2), (c) and Fig. 5 (2), (
6) is a diagram showing the configuration and output characteristics of a linear comparator, and FIGS. 6(2) and 6(c) are configuration diagrams showing a conventional example of a sensor section. (Explanation of symbols) 1 1...Sensor section, 2...Discrimination section,
3... Alarm section, 4... Magnet, 5
...Reed switch, 6 ... Window comparator, 7 ... Latch circuit, 8 ...
...Oscillator, 9...Speaker, 10.11.
...i Comparator, 12...AND gate.

Claims (1)

[Claims] A sensor unit includes a circuit in which a resistor of a predetermined value is connected in series to a switching element that opens when detecting movement of an object to prevent theft, etc., and a voltage generated based on a current flowing through the resistor when the switching element is closed. A predetermined reference voltage range including a value is set, and a discrimination unit outputs a command signal when the voltage value deviates from the reference voltage range, and an alarm unit that notifies an abnormality by the command signal. Prevention device.