JPH0512866Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a shield card for resonant markers for monitoring articles, and more specifically, for library lending books,
The present invention relates to an improvement in a shield card that makes a resonant marker used to prevent theft of rental records and other items in a rental business undetectable during regular use of the item.

[Prior Art] A radio frequency article monitoring device attaches a resonant marker equipped with a resonant circuit to an article and provides a monitoring area where radio waves of a predetermined frequency are radiated through which the article always passes. When passing through the monitoring area, the resonant marker on the article is configured to generate a resonant current in response to radio waves, and to detect this resonant current and issue an alarm. According to the article monitoring device, the theft of articles can be prevented with this configuration.

On the other hand, in the above-mentioned article monitoring device, articles may be allowed to pass through the monitoring area for originally legitimate purposes, such as when lending out books. In such a case, it is inconvenient for the resonance marker to operate and generate an alarm. Therefore, a shield card that disables the operation of the resonant marker has been proposed.

A conventional shield card has a structure as shown in FIG. 3, for example. This shield card consists of a shielding metal foil 30 made of aluminum or the like and two pieces made of paper or the like.
It is formed by sandwich-like covering from both sides with a sheet of packaging material 31. When this shield card 32 is attached to the resonant marker 34 so as to cover it, the metal foil 30 blocks the radio waves that should be given to the resonant circuit of the resonant marker 34, so a resonant current is generated in the resonant marker 34. Therefore, the resonance marker 34 becomes undetectable. In this way, the resonance marker 34 is
Once inoperable, the article to which the resonant marker 34 is attached can be moved freely within the monitored area without causing an alarm.

[Problems to be solved by the invention] According to the conventional shield card 32 having the above configuration, the resonance marker 3
4 can be effectively prevented. However, since the shield card 32 merely includes a conductive member, the monitoring device cannot detect when only the shield card 32 passes through the monitoring area. For this reason, the shield card 32 is illegally carried through the surveillance area, and the shield card 32 is placed on the resonant marker 34 of the desired article.
There is a problem in that it is not possible to prevent items from being stolen by making the resonant marker 34 undetectable.

In order to effectively solve the above-mentioned problems, the purpose of this invention is to provide the original shielding function that prevents the resonant operation of the resonant marker, and the purpose of the present invention is to provide a shield card that prevents the resonant operation of the resonant marker, and to prevent fraudulent activities such as bringing a shield card through a surveillance area and using it to steal goods. It is an object of the present invention to provide a shield card for a resonant marker for article monitoring, which also has a function of making it possible to detect the shield card itself in a monitoring area in order to prevent this.

[Means for Solving the Problems] The shield card of the resonant marker for article monitoring according to the present invention has a resonant marker attached to the article, and the resonant marker resonates in response to radio waves, thereby preventing unauthorized access to the article. The article monitoring device for preventing removal is configured to include a resonant circuit that changes a resonance condition of the resonant marker when placed near the resonant marker and operates in resonance in response to the radio waves.

[Function] In the shield card of the resonant marker for object monitoring according to the present invention, when the shield card is attached to the resonant marker, the resonant marker becomes undetectable, so the object can be moved freely in the monitoring area and used normally. In addition, it is possible to detect if only the shield card is illegally brought in.

[Example] An example of the present invention will be described below based on the accompanying drawings.

In FIG. 1, 1 is a book pocket, and the book pocket 1 is attached to, for example, books loaned out at a library. A resonant marker 3 is disposed within the pocket portion 2 of the book pocket 1.
The resonant marker 3 has a known resonant circuit made up of a combination of a planar coil and a capacitor, and has an overall shape of, for example, a rectangular sheet. The resonant circuit of the resonant marker 3 has a resonance condition designed so that it generates a resonant current in response to radio waves of a predetermined frequency (predetermined frequency). When the resonance marker 3 passes, a resonance current is caused to flow on the condition that the radio wave passes through the planar coil. When a resonant current flows through the resonant marker 3, a sensor (not shown) detects this resonant current, and an alarm is activated to issue an alarm. Such a sheet-like resonance marker 3
is attached to the inside surface of the book pocket 1 that is not visible to the public.

4 is a shield card; shield card 4
is provided with a resonance marker 5 almost at its center.
Further, the shield card 4 usually has the function of a card that records the rental status by printing predetermined information on its surface. The shield card 4 is not inserted into the book pocket 1 at first, but necessary information is recorded at the time of lending, and then the shield card 4 is used by being inserted into the book pocket 1. The resonance marker 5 is generally the resonance marker 3 described above.
Although it has exactly the same structure and function as
Further, it can also be configured as a resonant marker including a resonant circuit that produces a similar resonant effect. That is,
Changing the resonance condition of the resonance marker 3 when it is near the resonance marker 3 to prevent resonance operation,
It is sufficient that the resonant circuit of the resonant marker 5 itself causes a resonant operation in response to the radio waves. As shown in FIG. 2, the shield card 4 consists of a substrate 6 and a resonance marker 5, and the substrate 6 and the resonance marker 5 are separate bodies. The substrate 6 is made of any material, usually a non-conductor, and has a shape that allows it to be easily inserted into the book pocket 1. To be precise, the mounting position of the resonant marker 5 on the board 6 is such that when the board 6 is inserted into the book pocket 1, the resonant markers 3 and 5 completely match and overlap, or the resonant marker 5 covers the resonant marker 3. It is a perfect position. However, this is not strictly required, and can be changed as desired within a range that can effectively prevent the generation of resonance current in the resonance marker 3. Further, in the shield card 4, it is not necessarily necessary to separate the substrate 6 and the resonance marker 5. For example, it can be made of the resonant marker itself, having a shape corresponding to the substrate 6 and having rigidity. Furthermore, the resonance marker 5 can be made to have a larger area than the resonance marker 3. Generally, as shown in Figure 2, the resonance marker 5
It is preferable to form the shield card 4 by attaching the shield card to either the front or back surface of the substrate 6 or by sandwiching it between two substrates.

Next, the function of the shield card 4 will be explained. The resonant marker 3 in the book pocket 1 attached to the book generates a resonant current when the book passes within the monitoring area without using the shield card.
This will cause an alarm. When the shield card 4 is inserted into the book pocket 1, the resonance markers 3 and 5 overlap each other as shown in FIG. When the resonance markers 3 and 5 overlap in this way, the inductance and conductance values of each resonance marker 3 and 5 change, and the resonance conditions change. As a result, they become insensitive to the radio waves radiated in the monitoring area, No resonant current flows. Therefore, the shield card 4 can prevent the resonant operation of the resonant marker 3 of the book pocket 1, and conversely, the resonant operation of the resonant marker 5 of the shield card 4 is also prevented by the resonant marker 3. In this way, by using the shield card 4, it is possible to legitimately lend out books without triggering the detection operation accompanied by the notification of the alarm buzzer in the monitoring device.

Furthermore, even if the user passes through the monitoring area with the shield card 4 inserted into the book pocket 1 in order to return books, the monitoring device will not detect the same.

However, when only the shield cover 4 is brought into the monitored area, a detection operation is performed by the resonating marker 5, so that it is possible to prevent in advance any fraudulent acts caused by bringing in a shield card from the outside.

A specific example of a radio frequency article monitoring device using the shield card 4 as described above is ET-3000L manufactured by Sumitomo 3M Limited. Also,
As the resonant marker 5 disposed on either surface of a non-metallic substrate 6 such as paper or plastic, and the resonant marker 3 attached to the article, for example, a label tag manufactured by Sumitomo 3M Co., Ltd. is used.

[Effects of the invention] As is clear from the above explanation, according to the invention,
Since the shield card is formed using a resonant circuit, the function of shielding the resonant marker attached to the item makes the resonant marker undetectable during the normal original use of the item, while the resonant marker provided on the shield card itself This function makes it possible to detect the shield card itself, thereby preventing fraudulent acts such as theft of goods due to bringing in the shield card.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of the use of the shield card according to the present invention, FIG. 2 is an assembly diagram of the shield card according to the present invention, and FIG. 3 is an assembly diagram of a conventional shield card. Explanation of symbols: 1...Book pocket, 2...Pocket portion, 3...Resonance marker, 4...Shield card, 5...Resonance marker, 6...Substrate.

Claims (1)

[Scope of utility model registration request] An article monitoring device that prevents unauthorized removal of the article by attaching a resonant marker to the article and causing the resonant marker to resonate in response to radio waves, comprising a resonant circuit that causes resonance in response to the radio waves. and a shield card for a resonant marker for article monitoring, characterized in that when placed near the resonant marker, the resonant circuit changes the resonance condition of the resonant marker.