JP2000207652A - Burglar preventing system and monitoring system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain the miniaturization of a warning unit by sharing one antenna coil as antenna coils for receiving an announce signal and transmitting a warn ing signal. SOLUTION: The warning unit receives the announce signal generated from a robber prevention gate through a reception circuit composed of an antenna coil L and a capacitor C1, and inputs it through an amplifier 1 for reception to a central arithmetic circuit 2. When the announce signal is inputted, the central arithmetic circuit 2 sounds an alarm from a speaker 3 and outputs the warning signal through an amplifier 4 for transmission to a transmission circuit composed of the antenna coil L and a capacitor C2. At such a time, the central arithmetic circuit 2 turns on a switching transistor T and grounds a point P so that the configuration equal with a conventional transmission circuit can be provided and transmission from the antenna coil L is enabled. The switching transistor is small and inexpensive in comparison with the antenna coil so that miniaturization and price-down are attained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-theft system for protecting goods displayed in a store from fraudulent acts such as shoplifting, and more particularly, to a theft apparatus which emits an alarm at a gate device together with a tag device attached to the goods. It concerns prevention systems.

[0002]

2. Description of the Related Art Conventionally, a store which sells and sells products such as compact disk cassettes and magnetic tape cassettes employs an antitheft system as shown in FIG. 4 in order to protect these products from fraudulent acts such as shoplifting. Has adopted.

[0003] The anti-theft system is provided at an outlet 40 of a store.
It comprises an anti-theft gate 30 installed in the vicinity and an alarm unit 20 attached to a product 50.
The anti-theft gate 30 has a built-in circuit board 31 and a transmitting antenna (not shown). The circuit board 31 has a transmitting circuit (not shown) for generating an alarm activation signal (notification signal) for the alarm unit 20. .

As shown in FIG. 5, the alarm unit 20 includes a buzzer 22, a circuit board 23, a battery (not shown) and the like inside a casing 21, and a plurality of sound emission holes 24 are formed on the surface of the casing 21. At the same time, the alarm operation switch piece 25 is protruded. The buzzer 22 includes a circuit board 23
The operation is controlled by the alarm unit 20 when the alarm unit 20 is removed from the product 50 or
Sounds when passing through the anti-theft gate 30.

[0005] In a store, goods are displayed on a display stand with the alarm unit 20 attached. When a clerk sells a product to a customer, a specific signal is sent from a nullification device (not shown) to the circuit board 23 of the alarm unit 20 so that the buzzer 22 is not sounded, and then the alarm unit 20 is turned off. The customer removes the product from the product 50 and hands the product to the customer in exchange for the price.

[0006] The customer illegally moves the alarm unit 20 from the product 50.
Is removed, the alarm operation switch piece 25 is turned off, and the buzzer 22 sounds. When the customer illegally takes the product 50 out of the store together with the alarm unit 20, the circuit board 23 of the alarm unit 20 receives the alarm activation signal from the transmission antenna of the anti-theft gate 30, and the buzzer 22 It will sound.

Further, in Japanese Patent Application Laid-Open No. Hei 8-279082, a signal generator is also provided on the alarm unit 20 described above, and a response signal is transmitted in response to receiving an alarm activation signal from the anti-theft gate 30, An anti-theft device that sounds a buzzer provided on the anti-theft gate 30 by receiving the anti-theft gate 30 is described.

In such a device, since an alarm is issued from both the alarm unit 20 and the anti-theft gate 30, reliability in crime prevention can be improved.

[0009]

FIG. 3 shows the structure of a conventional alarm unit. In such an alarm unit, the notification signal is detected by the antenna coil L1 and the capacitor C1 as a receiving circuit, and is input to the central processing circuit 2 through the receiving amplifier 1. When the notification signal is input, the central processing circuit 2 sounds an alarm from the speaker 3 and outputs the alarm signal to the antenna coil L2 and the capacitor C2 as a transmission circuit through the transmission amplifier 4.

However, in such a conventional alarm unit,
The use of separate antenna coils in the receiving circuit and the transmitting circuit increases the size of the alarm unit to be attached to the product, deteriorating the appearance when displaying the product, and increasing the cost due to an increase in the number of parts. Problems arise.

[0011]

In order to solve the above-mentioned problems, in a theft prevention system according to the present invention, a notification signal transmitting device for transmitting a notification signal and an object for theft prevention are combined, and the notification signal transmitting device is provided. An alarm signal transmitting device that transmits an alarm signal having a frequency different from that of the notification signal while detecting that the notification signal has been received, and that an alarm signal has been received from the alarm signal transmitting device. Alarm signal receiving device that detects and issues an alarm
The alarm signal transmitting device is characterized in that one antenna coil is shared as an antenna coil for receiving a notification signal and transmitting an alarm signal.

According to another aspect of the present invention, there is provided an anti-theft system for transmitting a notification signal for transmitting a notification signal, and a notification signal from the notification signal transmission device, wherein the notification signal is transmitted from the notification signal transmitting device. Along with detecting the reception and issuing an alarm, an alarm signal transmitting device that transmits an alarm signal having a frequency different from the notification signal, and detecting that an alarm signal from the alarm signal transmitting device has been received. An anti-theft system including an alarm signal receiving device that issues an alarm, wherein the alarm signal transmitting device has a control circuit having an input terminal to which the notification signal is input and an output terminal to output the alarm signal, An antenna coil having one end connected to the input end of the control circuit; a first capacitor having one end connected to the input end of the control circuit and the other end grounded; And the other end is connected to the other end of the Nakoiru has a second capacitor connected to the output terminal of the control circuit.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a circuit block diagram showing the configuration of an alarm unit according to the present invention. The same elements as those in the prior art shown in FIG.

The difference from the conventional example of the present invention is that the capacitor C1 is connected in parallel to one antenna coil L and the capacitor C2 is connected in series, so that the antenna coil L is shared by the receiving circuit and the transmitting circuit. It is that. The point P side of the antenna coil L is grounded by the input signal from the central processing circuit 2 through the switching transistor T. In the alarm unit of this embodiment, the frequency of the notification signal to be received is 37.5 kHz,
The frequency of the alarm signal to be transmitted is 5.4 kHz.

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

First, the alarm unit receives an annunciation signal emitted from an anti-theft gate (not shown) by a receiving circuit including an antenna coil L and a capacitor C1, and inputs the signal to the central processing circuit 2 through the receiving amplifier 1. At this time, since the notification signal has a higher frequency than the transmission signal, the capacitance of the capacitor C2 as the transmission circuit is set to be sufficiently larger than the capacitance of the capacitor C1 as the reception circuit. That is, the capacitor C2 is connected to the capacitor C1.
Therefore, the antenna circuit L has a configuration equivalent to that of the conventional receiving circuit, and can be received by the antenna coil L. At this time, the switching transistor T is off.

When the notification signal is input, the central processing circuit 2
Generates an alarm from the speaker 3 and outputs an alarm signal to a transmission circuit including the antenna coil L and the capacitor C2 through the transmission amplifier 4. At this time, the central processing circuit 2 turns on the switching transistor T and grounds the point P, so that the configuration becomes equivalent to that of the conventional transmission circuit, and transmission from the antenna coil L is possible.

According to this embodiment, although one switching transistor is added as compared with the conventional example, one antenna coil which has conventionally been used in two can be used. That is, the switching transistor is smaller and less expensive than the antenna coil, so that the alarm unit of the present embodiment can be reduced in size and cost.

In the alarm unit, when an alarm is sounded, a stop signal from an alarm stop device (not shown) is detected to stop the alarm. That is,
In the apparatus of this embodiment, as shown in FIG. 2, after starting the alarm, the central processing circuit 2 causes the transmission of the alarm signal and the reception of the stop signal alternately. The stop signal has the same frequency as the notification signal and a different signal pattern.

In this embodiment, an example in which an alarm sound is issued from the alarm unit has been described. However, the function of issuing an alarm sound from the alarm unit in this embodiment is omitted, and the alarm unit detects the notification signal and outputs only the alarm signal. As an emission configuration, the alarm unit can be used as a monitoring system for monitoring that an object to which an alarm unit is coupled has passed a predetermined area (an area where a notification signal reaches).

[0022]

According to the present invention, since the antenna coil of the receiving circuit and the transmitting circuit of the alarm unit are commonly used, the size of the alarm unit can be reduced, and the appearance of the product when displayed is impaired. Disappears.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing an embodiment of an alarm unit according to the anti-theft system of the present invention.

FIG. 2 is a diagram showing transmission and reception timings in the alarm unit according to the present invention.

FIG. 3 is a circuit block diagram showing a conventional alarm unit.

FIG. 4 is a perspective view showing an anti-theft gate installed near an outlet of a store.

FIG. 5 is a perspective view showing an alarm unit attached to a product.

[Description of Signs] 1 Receiver amplifier 2 Central processing circuit 3 Speaker 4 Transmission amplifier L Antenna coil C1 Capacitor C2 Capacitor T Switching transistor

Claims (5)

[Claims] 1. An information signal transmitting device for transmitting an information signal, and an object to be stolen, which is coupled to the information signal transmitting device, detects that a notification signal from the information signal transmitting device is received, and issues an alarm. In an anti-theft system including an alarm signal transmitting device that transmits an alarm signal having a frequency different from the signal and an alarm signal receiving device that detects that an alarm signal has been received from the alarm signal transmitting device and issues an alarm. The alarm signal transmitting device is characterized in that one antenna coil is shared as an antenna coil for receiving a notification signal and transmitting an alarm signal. 2. The alarm signal transmitting apparatus according to claim 1, wherein, after detecting the notification signal, transmitting the alarm signal and receiving a stop signal for stopping the alarm in a time sharing manner.
The anti-theft system described in 1. 3. The anti-theft system according to claim 1, wherein the alarm signal and the notification signal have different frequencies. 4. A notification signal transmitting device for transmitting a notification signal, and an object to be stolen is detected. When the notification signal from the notification signal transmitting device is received, an alarm is issued, and the notification is issued. In an anti-theft system including an alarm signal transmitting device that transmits an alarm signal having a frequency different from the signal and an alarm signal receiving device that detects that an alarm signal has been received from the alarm signal transmitting device and issues an alarm. The alarm signal transmitting device has a control circuit having an input end to which the notification signal is input and an output end to output the alarm signal, an antenna coil having one end connected to the input end of the control circuit, and one end having A first capacitor connected to the input end of the control circuit and the other end grounded; one end connected to the other end of the antenna coil and the other end connected to the output end of the control circuit; An anti-theft system comprising a continuous second capacitor. 5. A broadcast signal transmitting apparatus for transmitting a broadcast signal, and a frequency different from the broadcast signal, being coupled to an object to be monitored, detecting that the broadcast signal has been received from the broadcast signal transmitting apparatus and detecting the broadcast signal. An alarm signal transmitting device for transmitting an alarm signal of the above, and a monitoring system including an alarm signal receiving device for detecting the reception of the alarm signal and issuing an alarm, the alarm signal transmitting device includes one antenna coil A monitoring system, which is commonly used as an antenna coil for receiving a notification signal and transmitting a warning signal.