JPS63144281A - Frequency sensor - Google Patents

Abstract

PURPOSE:To obtain a sensor capable of sending and receiving signals of different frequencies by connecting pattern parts in different shapes to a multiplying diode through a changeover switch. CONSTITUTION:Transmitting antenna pattern parts 2A, 2B, and 2C which are formed in nearly rectangular shapes and transmit radio waves of freqneicies determined by the shapes are provided in receiving antenna pattern parts 1A, 1B, and 1C which are formed in nearly U shape and receive radio waves of frequencies determined by the shapes, and both patterns are connected to the multiplying diode 6 through changeover switches 8a and 8b. Then when the receiving antenna pattern parts 1A, 1B, and 1C receive the radio waves of the frequencies determined by their shapes, the transmitting antenna pattern parts 2A, 2B, and 2C send radio waves of frequencies which are integral multiples of the reception frequencies. Thus, the changeover switches 8a and 8b are operated to switch and connect both pattern parts which differ in shape to the multiplyihng diode 6, so the signals of the different frequencies can be sent and received.

Description

[Detailed Description of the Invention] [Object of the Invention] - (Industrial Application Field) The present invention relates to a frequency sensor called a tag card, which is being used as a means to prevent theft of products, for example, in department stores. This invention relates to a frequency sensor that can transmit and receive radio waves of multiple frequencies.

(Prior art) Conventionally, as this type of frequency sensor, Japanese Patent Application Laid-Open No. 58-2
Some of these are explained in detail in Japanese Patent Laid-Open No. 00180, Japanese Patent Laid-Open No. 58-200187, and the like. That is, as shown in FIG. 2, the receiving antenna pattern section 1 is formed into a substantially U-shape and is capable of receiving radio waves at a frequency determined by the shape.
A transmitting antenna pattern section 2 is provided therein, which is formed into a substantially rectangular shape and is capable of transmitting radio waves at a frequency determined by the shape, and a multiplier diode 6 is provided between both patterns 1 and 2. Here, the above-mentioned elements are arranged on a component mounting body such as a wiring board.

This configuration will be described in more detail. That is, each corner 4a of the side opposite to the long side 3a of the receiving antenna pattern part l,
From 4b is a connecting conductor pattern 5a.

5b are pulled out and connected to the long side portions 3a, respectively. The anode of the multiplier diode 6 is connected to a bent portion 7 between the long side 3b and the short side 3C of the receiving antenna pattern section 1. Further, the cathode of the multiplier diode 6 is connected to the corner portion 4c of the transmitting antenna pattern portion 2.

This configuration has an electrical equivalent circuit as shown in FIG. 3. In FIG. 3, capacitor C1 and coil L1 are distributed constants determined by the shape of receiving antenna pattern section 1 in FIG. 2, and the receiving tuning frequency is determined by capacitor CI and coil L1. Capacitor C2 and coil L2 are distributed constants determined by the shape of transmitting antenna pattern section 2 in FIG. 2, and the transmitting tuning frequency is determined by capacitor C2 and coil L2.

Its operation is such that when the receiving antenna pattern section 1 receives a signal of a predetermined frequency, the transmitting antenna pattern section 2 sends a signal at a frequency that is an integral multiple of the receiving frequency (normally, the transmitting frequency is set to 2f relative to the receiving frequency f). It can be said to be a small-sized identification card that uses microwaves and does not require a power source.

This sensor is used as a theft prevention measure in department stores, etc. by attaching this frequency sensor to a product, and using a transmitter that can send a signal at a reception frequency specific to the sensor, and a receiver that can receive a signal at a frequency that is an integral multiple of this frequency. A transmitting/receiving system consisting of a machine and a machine is installed at the entrance/exit of the checkout office. If the clerk at the checkout office removes the frequency sensor from the product that has been paid for, then when a product that has not yet been paid for leaves the checkout counter, the transmitter/receiver system will respond to the frequency sensor and issue an alarm, etc. It now outputs an alarm, which is effective as a measure to prevent product theft. However, if a plurality of sensors exist in a transmitting/receiving area, it is possible to determine the presence or absence of a sensor, but it is impossible to identify the product to which the sensor is attached and the person who owns the product. As a means to solve this problem, if a sensor with a different frequency is attached to each product, and a transmitter and receiver corresponding to each sensor are installed, the product with the sensor attached and the person holding it can be identified. It becomes possible to make detailed identifications such as In this case, sensors with different frequencies are required,
This was not practical as it sometimes caused confusion in the management of sensors.

(Problem to be solved by the invention) As described above, since conventional frequency sensors are configured to be able to transmit and receive signals of only one frequency, it is difficult to determine whether a sensor is present or not. It was not possible to make detailed distinctions.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a frequency sensor capable of transmitting and receiving signals of different frequencies.

[Structure of the Invention] (Means for Solving the Problems) The present invention is characterized by taking the following measures in order to solve the above problems and achieve the object. That is, the present invention provides a transmitting antenna pattern formed in a substantially rectangular shape and capable of transmitting radio waves at a frequency determined by the shape, within a receiving antenna pattern portion formed in a substantially U-shape and capable of receiving radio waves at a frequency determined by the shape. and a multiplier diode is provided between both patterns, and when the antenna pattern section receives radio waves with a frequency determined by its shape, the transmitting antenna pattern section transmits radio waves with a frequency that is an integral multiple of the receiving frequency. Zhou to send,
The wave number sensor is characterized in that each of the pattern portions has a plurality of different shapes, and includes a switching means for selectively connecting each of the pattern portions of the plurality of different shapes to the multiplier diode.

(Function) By taking such a measure, by operating the switching means, it is possible to switch and connect each of the plurality of pattern sections of different shapes to the above-mentioned multiplier diode, and the transmission and reception frequencies of the two pattern sections can be changed. Since it is determined by its shape, signals of different frequencies can be transmitted and received.

(Embodiment) An embodiment of the frequency sensor according to the present invention will be described below with reference to FIG. 1, in which the same parts as in FIGS. 2 and 3 are denoted by the same reference numerals.

In this embodiment, the receiving antenna pattern section has three different shapes, for example, IA, IB, and IC, which are formed in a substantially U-shape and can receive radio waves of a frequency determined by the shape. In addition, as a transmitting antenna pattern section that is formed into a substantially rectangular shape and can transmit radio waves of a frequency determined by the shape, there are, for example, three different shapes 2A, 2B, and 2.
It has C. Both patterns IA have different shapes.

Selector switch 8a between IB, IC and 2A, 2B, 2C
, 8b are provided with a multiplier diode 6. Each of these elements is arranged using a conductor or the like on a component mounting body such as a printed circuit board.

Here, both patterns IA, IB, IC, and 2A.

For 2B and 2C, in addition to actually arranging different shapes on printed circuit boards, a standard pattern is set, and patterns for changing the long side, short side, etc. By configuring to add or delete patterns, it is possible to substantially configure a plurality of patterns. In addition, the changeover switches 8a and 8b are assumed to perform switching operations in conjunction with each other, and their specific configuration includes forming a fixed contact and a movable contact on a printed circuit board by patterning them with a conductor. This enables the realization of an ultra-compact switch.

In this embodiment configured in this way, the changeover switches ga,
By operating gb, the receiving antenna pattern portion IA of a different shape is formed in the multiplier diode 6.

Either IB or IC is connected to the corresponding transmitting antenna pattern sections 2A, 2B, and 2C, and the transmitting and receiving frequency is that of both pattern sections IA.

Since it is determined by the shapes of IB, IC, 2A, 2B, and 2C, signals of different frequencies can be transmitted and received.

[Effects of the Invention] As described above, the present invention has a receiving antenna pattern section that is formed in a substantially square shape and can receive radio waves with a frequency determined by the shape, within a receiving antenna pattern section that is formed in a substantially U-shape and can receive radio waves with a frequency determined by the shape. A transmitting antenna pattern section is provided, and a multiplier diode is provided between both patterns, and when the receiving antenna pattern section receives a radio wave with a frequency determined by its shape, the receiving frequency is In a frequency sensor that transmits radio waves with a frequency that is an integer multiple of , each of the pattern portions has a plurality of different shapes, and each of the pattern portions of the plurality of different shapes is selectively connected to the multiplier diode. It is characterized by being equipped with means.

According to this configuration, by operating the switching means, it is possible to switch and connect each of a plurality of different shaped pattern parts to the multiplier diode, and the transmission and reception frequencies by both pattern parts are determined by their shapes. Therefore, there is an effect that signals of different frequencies can be transmitted and received.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of a frequency sensor according to the present invention, and FIGS. 2 and 3 are diagrams showing a conventional example. IA, IB, IC...Receiving antenna pattern section, 2A
, 2B, 2C... transmitting antenna pattern section, 6...
Multiplier diode, GA, GB... selector switch.

Claims (1)

[Claims] A transmitting antenna pattern section is provided within a receiving antenna pattern section formed in a substantially U-shape and capable of receiving radio waves at a frequency determined by the shape, and a transmitting antenna pattern section formed in a substantially square shape and capable of transmitting radio waves at a frequency determined by the shape; In the frequency sensor, a multiplier diode is provided between both patterns, and when the receiving antenna pattern part receives a radio wave with a frequency determined by its shape, the transmitting antenna pattern part transmits a radio wave with a frequency that is an integral multiple of the receiving frequency. . A frequency sensor comprising: a plurality of pattern portions each having a plurality of different shapes; and a switching means for selectively connecting each of the plurality of pattern portions having different shapes to the multiplier diode.