JP2558330Y2 - Electromagnetic coupling type electronic equipment - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement of a coil portion used for a read / write head or a data carrier in an electronic device of an electromagnetic coupling system, for example, an ID system, and particularly to a structure for removing the common mode noise. It is.

[0002]

2. Description of the Related Art A conventional electromagnetic coupling type ID system comprises a data carrier for holding data, a read / write head arranged at a position facing the data carrier, an ID controller connected to the data carrier, and the like. The read / write head and the data carrier are
And transmit data to each other by electromagnetic coupling.
You. In such an ID system, common mode noise is removed by enclosing a circuit portion in a thin copper plate or brass plate.

[0003]

However, the conventional electromagnetic coupling type ID system has a drawback that the antenna coil portion is not shielded and is easily affected by common mode noise. Shielding the antenna coil eliminates the effects of noise, but the antenna coil
An eddy current flows through the shield plate by a magnetic field generated from the shield plate. Therefore, there is a disadvantage that the magnetic energy is consumed by the shield plate and the communication distance is shortened.

[0004] The present invention has been made in view of such problems of the conventional ID system, and has as its technical object to reduce the loss of magnetic energy and effectively remove noise. .

[0005]

Means for Solving the Problems The invention of claim 1 of the present application
Is an electromagnetic coupling type electronic device that transmits data in a non-contact manner by electromagnetic coupling by arranging antenna coils opposite each other, comprising an annular antenna coil and a core in which the antenna coil is embedded in an annular groove. A shield plate provided on the surface of the antenna coil exposed from the groove of the core,
It has a shield plate in the form a metal film for shielding the thin film
Form, eddy current generated by the antenna coil to the metal layer
Characterized in that a slit is provided so as to reduce the diameter of the vortex . The invention of claim 2 of the present application
In the electromagnetic coupling type electronic device of 1, the metal film is formed in a ring shape
And a small part that divides the metal film in the radial direction.
Characterized by having at least one slit
It is.

[0006]

According to the present invention having such a feature, the portion of the side surface of the antenna coil that is exposed from the core is used for shielding .
Is formed. The vortex generated in the metal film
Form a slit so that the eddy diameter of the current is small
This suppresses eddy currents. Like this
Then, there is no influence of noise, and data transmission and power transmission by magnetic flux passing through the core can be performed.

[0007]

FIG. 1 is an assembly diagram of a data carrier according to an embodiment of the present invention, and FIG. 2 is a front view of a shield plate used in the embodiment. As shown in these drawings, the data carrier 1 has an annular antenna coil 2 having a through hole at the center wound around a coil spool. The antenna coil 2 has a ferrite core 3 having an annular groove as shown in the figure.
Embedded in the groove and fixed integrally. On the back surface, a printed circuit board 6 constituting an electronic circuit portion of the data carrier is sandwiched and mounted between a pair of shield plates 4 and 5 having a U-shaped cross section to shield the electronic circuit portion.

In this embodiment, as shown in the figure, a disk-shaped shield plate 7 having substantially the same shape as the side surface 2a, that is, having an opening at the center and protruding portions at both ends, is attached to the side surface 2a of the antenna coil 2. As shown in FIG. 2, the shield plate 7 is formed by laminating a metal film 9 for shielding in a ring shape on a thin thin film, for example, a polyimide film 8. As shown, the shield plate 7 has an annular slit 10 which is substantially circular as a whole and extends along the central axis, and a slit 11 which extends along the radial direction. One end of the shield plate 7 is bent and electrically connected to the shield plates 4 and 5 for the circuit board described above. In this way, as shown in FIG. 3, common mode noise generated between the data carrier 1 and the read / write head 12 is effectively removed by the shield plate 7 attached to the antenna coil 2.

Here, as shown in FIG. 4A, if this shield plate is donut-shaped and does not have the slits 10 and 11, the magnetic energy generated from the data carrier and the read / write head causes the shield plate as shown by a broken line in the figure. An eddy current is generated. Therefore, the magnetic energy is consumed, and the communication distance is reduced by 1 / compared to the case where the shield plate is not used.
2 or less. Therefore, in order to reduce the influence of the eddy current, the eddy current can be reduced by providing a radial slit 11 as shown in FIG. 4B, and further, as shown in FIG. The eddy current can be greatly reduced by providing the slit 10. In this way, the influence of the eddy current is almost eliminated, and almost the same data transmission distance as when the shield plate is not attached can be realized.

[0010]

According to the present invention, as described in detail above, the common mode noise can be effectively removed by attaching the shield plate to the side surface of the antenna coil. Moreover, since the shield plate is provided with slits, the effect of the eddy current due to the attachment of the shield plate is reduced, and the effect of securing the original communication distance can be obtained.

[Brief description of the drawings]

FIG. 1 is an assembly configuration diagram of a data carrier according to an embodiment of the present invention.

FIG. 2 is a front view of a shield plate used in the embodiment.

FIG. 3 is a diagram illustrating a relationship between a data carrier, a read / write head, and common mode noise according to the present embodiment.

FIG. 4 is a diagram showing the relationship between shield plates of various shapes and eddy currents generated therein.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Data carrier 2 Antenna coil 2a Side surface 3 Ferrite core 7 Shield plate 8 Polyimide film 9 Metal film 10, 11 Slit

Claims (2)

(57) [Scope of request for utility model registration] 1. An electromagnetically coupled electronic device that transmits data in a non-contact manner by electromagnetic coupling by arranging antenna coils opposite to each other, wherein an annular antenna coil and the antenna coil are embedded in an annular groove. A core, and a shield plate provided on a surface of the antenna coil exposed from the groove of the core, wherein the shield plate forms a shielding metal film on a thin film.
And an eddy current generated by the antenna coil on the metal film.
An electromagnetically coupled electronic device , wherein a slit is provided so as to reduce a flow vortex diameter . 2. The metal film is formed in a ring shape.
At least one parting the metal film in the radial direction.
The slit according to claim 1, wherein two slits are provided.
Electromagnetic coupling type electronic equipment.