JP2000123262A - Theft prevention system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a system for generating an alarm at both a warning unit and a theft prevention gate by providing a first alarming unit, which is coupled with a theft prevention object, for sounding an electromagnetic buzzer and a second alarming unit for issuing the alarm by receiving an electromagnetic wave generated simultaneously with the sounding of the electromagnetic buzzer. SOLUTION: The first alarming unit B is coupled with the object of theft prevention. When the first alarming unit B gets close to a theft prevention gate A, a reception antenna 5 of this first alarming unit B receives the electromagnetic wave outputted from a transmission antenna 4 of the theft prevention gate A. Concerning this system, an electromagnetic buzzer 9 is sounded by detecting the first alarming unit B gets close to the theft prevention gate A (namely a notifying signal is received from the theft prevention gate A) or the first alarming unit B is disconnected from the object of theft prevention. At the same time, a second alarming unit C issues an alarm by receiving a higher harmonic wave generated from the electromagnetic buzzer 9 of the first alarming unit B as well.

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.

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

As shown in FIG. 5, a warning unit (20) includes a buzzer (22), a circuit board (23), and a battery inside a casing (21).
(Not shown) etc., a plurality of sound emission holes (24) are opened on the surface of the casing (21), and
(25) is protruded. The operation of the buzzer (22) is controlled by the circuit board (23), and when the alarm unit (20) is removed from the product (50), or the alarm unit (20) closes the anti-theft gate (30). Sounds when passing.

[0005] In a store, the product is an alarm unit.
Displayed on a display stand with (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) does not sound. In the alarm unit
(20) is removed from the product (50) and the product is handed to the customer in exchange for the price.

[0006] A customer illegally sends an alarm unit (20) from a product (50).
When the is removed, the alarm operation switch piece (25) is turned off, and the buzzer (22) sounds. Also, if 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) is moved from the transmitting antenna of the anti-theft gate (30). Upon receiving the alarm activation signal, the buzzer (22) will sound.

Further, in Japanese Patent Application Laid-Open No. Hei 8-279082, a signal generator is also provided on the alarm unit (20), and a response signal is received in response to the reception of an alarm activation signal from the anti-theft gate (30). Is transmitted, and when the anti-theft gate (30) receives it, an anti-theft device that sounds a buzzer provided on the anti-theft gate (30) side is described.

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

[0009]

However, Japanese Patent Laid-Open No.
In the anti-theft device described in JP-A-279082, since a circuit for generating and transmitting a signal is separately provided also on the alarm unit (20) side, the circuit configuration of the alarm unit (20) becomes complicated, There is a problem that the alarm unit (20) to be attached to the product itself becomes large and the appearance when displaying the product deteriorates.

[0010]

In order to solve the above-mentioned problems, an anti-theft system according to the present invention is combined with an alarm signal transmitting device for transmitting an alarm signal and an object to prevent theft, and an object to prevent theft is provided. A first alarm unit that emits an electromagnetic buzzer upon detecting that the connection state with the connection has been separated or that the notification signal from the notification signal transmitting device has been received;
A second alarm unit that detects that an electromagnetic wave generated simultaneously with the sounding of the electromagnetic buzzer has been received and issues an alarm.

In the anti-theft system according to the present invention, the electromagnetic wave detected by the second alarm unit is a second harmonic generated by an electromagnetic buzzer of the first alarm unit.

Further, in order to solve the above-mentioned problem, in the anti-theft system according to the present invention, a notification signal transmitting device for transmitting a notification signal is connected to an object to be stolen and connected to the object to be stolen. A first alarm unit that detects the disconnection or the reception of the notification signal from the notification signal transmitting device and emits a warning sound, and a harmonic that is generated simultaneously when the first warning unit generates a warning sound And a second alarm unit for issuing an alarm upon detecting the reception of the second alarm.

[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 the anti-theft system of the present invention, and FIG. 2 shows signal waveforms in each signal path.

In FIG. 1, A denotes an anti-theft gate. In the anti-theft gate A, (1) denotes a signal generator for generating a sine wave (sine wave) signal (see waveform 1 in FIG. 2). It is.

(2) is a burst control signal generator, which turns on the switch SW1 by a burst control signal (see waveform 2 in FIG. 2) using the SIN wave signal generated by the signal generator (1).
By turning on / off, a burst signal is generated (see waveform 3 in FIG. 2).

(3) is a transmission signal amplifying circuit, which includes a signal generator (1), a burst control signal generator (2), and a switch S.
The burst signal generated by W1 is amplified. Further, (4) is a transmitting antenna, and a transmitting signal amplifying circuit (3)
The burst signal (notification signal) amplified by the above is radiated into the air as an electromagnetic wave.

B shows the configuration of a first alarm unit, which is connected to an object to be stolen.

In the first alarm unit B, (5) is a receiving antenna, which is output from the transmitting antenna (4) of the anti-theft gate A when the first alarm unit B approaches the anti-theft gate A. Receives electromagnetic waves. And (6)
Is a reception signal amplifying circuit for amplifying a signal received by the reception antenna (5).

(7) is a control circuit, and a received signal amplifying circuit (6)
It is determined whether or not the received signal amplified in step (b) is a specified burst signal (broadcast signal). If the received signal is a specified burst signal, the buzzer driving circuit (8) at the subsequent stage is operated and the electromagnetic buzzer (9) is activated. Generates an audible alarm. The control circuit (7)
Detects that the first alarm unit A has been separated from the object to be stolen (not shown), activates the buzzer drive circuit (8), and generates an alarm sound from the electromagnetic buzzer (9). .

Here, the buzzer drive circuit (8) drives the electromagnetic buzzer (9) with a square wave as shown in FIG. In this embodiment, the driving frequency is 2.7 kHz and the duty is 25 to
A 35% square wave is used. At this time, the electromagnetic buzzer
From (9), the frequency is increased by n times (n = 2, 3,...) Together with the electromagnetic wave (fundamental wave) of 2.7 kHz which is the same as the driving frequency.
・) The n-th harmonic is generated simultaneously.

On the other hand, C shows the configuration of the second alarm unit. In the second alarm unit C, (10) is a receiving antenna, (11) is a received signal amplifying circuit, and
The signal received at (10) is amplified by the received signal amplifier (11).

(12) is a band-pass filter, which in this embodiment uses a filter transmitting a frequency of 5.4 kHz. That is, in the present embodiment, the second harmonic generated from the electromagnetic buzzer (9) when the first alarm unit B emits a warning sound passes through the band-pass filter (12).

(13) is a control circuit, which is a bandpass filter.
The signal (second harmonic) transmitted through (12) is detected, and the subsequent alarm generation circuit (14) is driven to generate an alarm (not shown) such as sound or light.

However, in this embodiment, the first alarm unit B coupled to the object of theft prevention approaches the antitheft gate A (that is, the first alarm unit B receives the notification signal from the antitheft gate A). ) Or detecting that the object has been separated from the anti-theft object, emits an electromagnetic buzzer, and the second alarm unit C also issues an alarm by receiving a harmonic generated from the electromagnetic buzzer of the first alarm unit B. It will be.

Here, the second alarm unit C may be built in the anti-theft gate A, or may be separately installed separately.

In this embodiment, an example in which the second harmonic is detected has been described. However, the transmission range of these harmonics is larger than that of the fundamental frequency band normally used for driving an electromagnetic buzzer. This is because the output of the second harmonic is relatively large among the harmonics. Of course, the transmission frequency of the band-pass filter (12) may be changed so as to detect a fundamental wave or a third or higher harmonic. For example, when detecting the third harmonic, the transmission frequency of the band-pass filter (12) may be set to 8.1 kHz. At this time, the electromagnetic buzzer
If the duty of the square wave signal for driving (9) is set to 50%, only odd-order harmonics are generated as harmonics, so that the output increases and detection becomes easier.

[0028]

According to the present invention, without providing a circuit for generating and transmitting a signal in the first alarm unit attached to the product, an alarm is generated by the anti-theft gate or the second alarm unit separately installed. Therefore, the circuit configuration of the first alarm unit can be simplified, and the first alarm unit to be attached to the product does not become large.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing a configuration of a theft prevention system according to the present invention.

FIG. 2 is a diagram showing a notification signal waveform in the anti-theft system of the present invention.

FIG. 3 is a diagram showing an electromagnetic buzzer driving waveform in the anti-theft system of the present invention.

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.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 signal generator 2 burst control signal generator 3 transmission signal amplification circuit 4 transmission antenna 5 reception antenna 6 reception signal amplification circuit 7 control circuit 8 buzzer drive circuit 9 electromagnetic buzzer 10 reception antenna 11 reception signal amplification circuit 12 bandpass filter 13 control Circuit 14 Alarm generation circuit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5C084 AA03 AA09 BB33 CC35 DD07 DD74 GG07 GG09 GG23 GG33 GG38 GG39 GG57 GG65 GG74 HH03

Claims (3)

[Claims] An information signal transmitting apparatus for transmitting an information signal is coupled to an object to be stolen, and the state of connection with the object to be stolen is disconnected, or an information signal from the information signal transmitting apparatus is received. A first alarm unit that emits an electromagnetic buzzer upon detecting that the electromagnetic wave has been emitted, and a second alarm unit that emits an alarm by detecting the reception of an electromagnetic wave generated simultaneously when the electromagnetic buzzer sounds. Anti-theft system. 2. The electromagnetic wave detected by the second alarm unit,
The anti-theft system according to claim 1, wherein the second alarm is a second harmonic generated from an electromagnetic buzzer of the first alarm unit. 3. A notification signal transmitting device for transmitting a notification signal and an anti-theft object are coupled to each other, and a connection state between the anti-theft object and a notification signal from the information signal transmitting device is received. A first alarm unit that emits a warning sound by detecting that the alarm has been performed, and a second alarm unit that emits an alarm by detecting that the first alarm unit has received harmonics generated simultaneously when the first alarm unit generates the alarm sound. An anti-theft system comprising: