JPS58200187A - Detecting method by sensor - Google Patents

Abstract

PURPOSE:To prevent commodities from being stolen by using a signal from a frequency sensor provided within a radiation area of a transmission wave. CONSTITUTION:An electromagnetic wave having a prescribed frequency is radiated constantly from a transmission antenna 2 into an area. When a frequency sensor 3 set in this area receives a transmission wave, radiates, as an output, an electromagnetic wave having a frequency higher by an integer multiple than the frequency of the transmission wave. The wave radiated from said sensor 3 is received by an antenna 4, and a reception signal is supplied to a receiver 5. When an alarm generator 6 is operated in the presence of the reception signal, the presence of the sensor 3 can be recognized from the presence of an alarm. Accordingly, commodities can be prevented from being stolen by sticking the sensor 3 to the commodities beforehand.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sensor detection method in which, for example, a frequency sensor attached to a product is placed in a radio wave emission area and the presence of the sensor in the area is detected.

In recent years, stores such as Dehart stores and supermarkets have taken various measures to prevent product theft. One of these measures is to station security guards inside the store. However, if the product is relatively small, it is extremely difficult for only a small number of security guards to prevent theft.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sensor detection method that is extremely simple and can be reliably used for theft prevention.

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

In FIG. 1, 1 is a transmitter that transmits high-frequency power at a predetermined frequency, and this transmitter 1 includes an oscillation section 1m, an amplification section 1m, and an amplification section 1m.
b and a power amplification section 1c. Transmitter 1
The high frequency power output from the transmitting antenna 2 is continuously radiated within a predetermined area. Reference numeral 6 denotes a frequency sensor whose details will be described later. This sensor 6 has the function of receiving the high frequency power from the transmitter 1, multiplying it to a frequency that is an integral multiple of the receiving frequency, and transmitting it again. Radio waves transmitted from the sensor 6 are received by the receiving antenna 4. This receiving antenna 4 is set to the transmission frequency of sensor B, and the received signal is supplied to a receiver 5. The receiver 5 includes a first frequency converter 5ax, a second frequency converter 5b, a third frequency converter 5C, and a relay circuit 5d.
is formed from. The output signal of the receiver 5 is supplied to an alarm generator 6, such as a buzzer.

In the embodiment configured as described above, radio waves of a predetermined frequency are constantly radiated into the area from the transmitting antenna 2. When the frequency sensor 6 placed within this area receives the transmitted radio wave, it emits as an output a radio wave having a frequency that is an integral multiple of the received radio wave. Radio waves radiated from the sensor 6 are received by the receiving antenna 4, and the received signal is supplied to the receiver 5. If the alarm generator 6 is operated when the receiver 5 signal is present, that is, when the sensor 6 is present in the Erina, the presence of the sensor B can be recognized from the presence or absence of an alarm.

If the sensor 6 described above is attached to a product at a store, for example, it is possible to prevent theft of the product by taking it outside without purchasing it properly.

Next, a specific example of the above-mentioned sensor B is shown in FIG.

In FIG. 2, reference numeral 11 denotes a receiving antenna pattern section formed on a printed board (not shown), and this receiving antenna pattern section 11 is formed in a substantially U-shape. A transmitting antenna pattern section 12 is disposed within the receiving antenna pattern section 11 . The transmitting antenna pattern section 12 is formed into a substantially rectangular shape, and connection conductor patterns 15a and 15b are drawn out from each corner section 14m and 14b of the side opposite to the long side section 13a of the receiving antenna pattern section 11. They are each separately connected to the section 13a. Reference numeral 16 denotes a multiplier diode consisting of a varactor diode, and the anode of this diode 16 is connected to a bent portion 17 of the long side 13b and short side 13c of the receiving antenna pattern section 11 at 1°. Further, the cathode of the diode 16 is connected to the corner portion 14c of the transmitting antenna pattern portion 12.

Note that the electrical equinodal circuit of the sensor shown in Figure 2 is
As shown in the figure. In Figure 3, capacitor CI and coil L
is a distributed constant determined by the shape of the receiving antenna pattern section 11 in FIG. 2, and the receiving tuning frequency is determined by the capacitor C1 and the coil Ll. Further, the capacitor C2 and the coils 1 and 2 are distributed constants that are similarly determined by the shape of the transmitting antenna pattern section 12, and the transmitting tuning frequency is determined by the capacitor C2 and the coil L2.

In the embodiment shown in FIG. 1, the receiving antenna 4, receiver 5, and alarm generator 6 may be formed into a portapull type.

However, in the embodiment shown in FIG. 1, the case where it can be used to prevent product theft has been described as an example, but it can also be used for the following purposes.

(b) Linking with security cameras, e.g. sensor 6
Activates the camera when you take out an object that has been affixed to it.

(b) Using a key, for example, using sensor 6 and a key lock, and releasing the key lock by sensor B. This makes it possible to prevent anyone other than the person holding the sensor 3 from entering the room.

(c) Preventing people from entering dangerous areas, for example, having visitors carry a sensor 6 (as a name tag) to issue an alarm if they enter a place they are not allowed to enter.

2) Use the sensor 6 to prevent items from being left behind, for example, attaching the sensor 6 to belongings that must be taken out, locking the opening/closing door with a key, and using the sensor 6 to release the door.

As described above, according to the present invention, a frequency sensor is provided within the radiation area of the transmitted radio waves, and the sensor ~
When receiving radio waves radiated from the sensor and receiving a signal from the sensor, it can be easily recognized that the sensor is within the area, so it can be used to prevent theft of products, etc.

[Brief explanation of drawings]

FIG. 1 is a schematic structural explanatory diagram showing an embodiment of the present invention;
FIG. 2 is an explanatory diagram of a specific configuration of the frequency sensor, and FIG. 3 is an electrical equivalent circuit diagram of FIG. 2. 1... Transmitter, 2... Transmitting antenna, 3... Frequency sensor, 4... Receiving antenna, 5... Receiver,
6...Alarm generator. Patent applicant: Samba-Ichi Kogyo Co., Ltd. Patent attorney Terumasa Tsukuda (Figure 1)

Claims (1)

[Claims] (1) Radio frequency power of a predetermined frequency sent out from a transmitter is radiated from an antenna, and a frequency sensor is installed within the radiation region that is tuned to the frequency and multiplies the frequency to an integral multiple higher than that frequency and transmits it again. The radio waves emitted from the sensor are received by a receiving antenna and supplied to the receiver, and the presence or absence of the radio waves is detected from the output of the receiver to determine whether the sensor is present within the radiation area. A sensor detection method characterized by making a judgment.