Method for producing antenna device
A method for manufacturing an antenna device may include a first step of forming an antenna circuit so that the resonance frequency of the antenna circuit will be lower than an oscillation frequency of the reader/writer. The antenna circuit includes an antenna coil that receives the magnetic field transmitted from the reader/writer and a capacitor electrically connected to the antenna coil. The manufacturing method also includes a second step of affixing a magnetic sheet to the antenna coil via an adhesive. The magnetic sheet is at a face-to-face position with respect to the antenna coil and is configured to change the inductance of the antenna coil. The adhesive is of a film thickness to change the inductance so that the resonance frequency of the resonance circuit will be coincident with the oscillation frequency depending on the spacing between the antenna coil and the magnetic sheet.
1. A method for manufacturing an antenna device that is inductively coupled to a transmitter on receipt of a magnetic field transmitted at a preset oscillation frequency from the transmitter to provide for a communication enabled state, the method comprising:
forming a resonance circuit including an antenna coil that receives the magnetic field transmitted from the transmitter and a variable capacitance capacitor electrically connected to the antenna coil so that a resonance frequency of the resonance circuit will be adjustable; and
affixing a magnetic sheet to the antenna coil via an insulation material,
wherein the magnetic sheet is formed at a face-to-face position with respect to the antenna coil and configured to change an inductance of the antenna coil, and a thickness of the insulation material allows the inductance to change so that the resonance frequency of the resonance circuit is coincident with the oscillation frequency depending on a spacing between the antenna coil and the magnetic sheet, and
wherein the affixing of the magnetic sheet comprises:
measuring the resonance frequency of the resonance circuit; and
affixing the magnetic sheet to the antenna coil via the insulation material having the thickness which, based on measured results of the resonant frequency, will provide for the resonance frequency of the resonance circuit coincident with the oscillation frequency.
2. The method according to claim 1 , wherein the forming of the resonance circuit comprises using a capacitor formed of a ferroelectric material, and the capacitance of the capacitor decreases monotonously with rise in temperature.
3. The method according to claim 1 , wherein the affixing of the magnetic sheet comprises arranging the magnetic sheet via the antenna coil on an electrical wave signal receiving side.
4. The method according to claim 1 , wherein the affixing of the magnetic sheet comprises varying the spacing by applying pressure at an angle relative to a direction normal to the surface of the antenna coil or to the surface of the magnetic sheet.
5. A method for manufacturing an antenna device that is inductively coupled to a transmitter on receipt of a magnetic field transmitted at a preset oscillation frequency from the transmitter to provide for a communication enabled state, the method comprising:
forming a resonance circuit including an antenna coil that receives the magnetic field transmitted from the transmitter and a variable capacitance capacitor electrically connected to the antenna coil so that a resonance frequency of the resonance circuit will be adjustable; and
affixing a magnetic sheet to the antenna coil via an insulation material,
wherein the magnetic sheet is formed at a face-to-face position with respect to the antenna coil and configured to change an inductance of the antenna coil, and a thickness of the insulation material allows the inductance to change so that the resonance frequency of the resonance circuit is coincident with the oscillation frequency depending on a spacing between the antenna coil and the magnetic sheet, and
wherein the affixing of the magnetic sheet comprises:
affixing the antenna coil to the magnetic sheet via an adhesive, curable by preset curing processing, as the insulation material;
changing the spacing as the resonance frequency of the resonance circuit is measured; and
curing the adhesive to affix the antenna coil and the magnetic sheet together when the resonance frequency of the resonance circuit has become equal to the oscillation frequency.
6. The method according to claim 5 , wherein the adhesive contains 5 to 30 wt % of elastic particles or a foaming agent.
7. The method according to claim 5 , wherein the affixing of the magnetic sheet comprises varying the spacing by applying pressure at an angle relative to a direction normal to the surface of the antenna coil or to the surface of the magnetic sheet.
8. The method according to claim 5 , wherein the forming of the resonance circuit comprises using a capacitor formed of a ferroelectric material, and the capacitance of the capacitor decreases monotonously with rise in temperature.
9. The method according to claim 5 , wherein the affixing of the magnetic sheet comprises arranging the magnetic sheet via the antenna coil on an electrical wave signal receiving side.
10. A method for manufacturing an antenna device that is inductively coupled to a transmitter on receipt of a magnetic field transmitted at a preset oscillation frequency from the transmitter to provide for a communication enabled state, the method comprising:
forming a resonance circuit including an antenna coil that receives the magnetic field transmitted from the transmitter and a variable capacitance capacitor electrically connected to the antenna coil so that a resonance frequency of the resonance circuit will be adjustable; and
affixing a magnetic sheet to the antenna coil via an insulation material,
wherein the magnetic sheet is formed at a face-to-face position with respect to the antenna coil and configured to change an inductance of the antenna coil, and a thickness of the insulation material allows the inductance to change so that the resonance frequency of the resonance circuit is coincident with the oscillation frequency depending on a spacing between the antenna coil and the magnetic sheet, and
wherein the affixing of the magnetic sheet comprises:
varying the spacing as the resonance frequency of the resonance circuit is measured; and
introducing, as the insulation material, an adhesive curable by preset processing of curing between the antenna coil and the magnetic sheet and cured in situ after the resonance frequency of the resonance circuit is equal to the oscillation frequency in order to affix the antenna coil and the magnetic sheet together.
11. The method according to claim 10 , wherein the affixing of the magnetic sheet comprises varying the spacing by applying pressure at an angle relative to a direction normal to the surface of the antenna coil or to the surface of the magnetic sheet.
12. The method according to claim 10 , wherein the adhesive contains 5 to 30 wt % of elastic particles or a foaming agent.
13. The method according to claim 10 , wherein the forming of the resonance circuit comprises using a capacitor formed of a ferroelectric material, and the capacitance of the capacitor decreases monotonously with rise in temperature.
14. The method according to claim 10 , wherein the affixing of the magnetic sheet comprises arranging the magnetic sheet via the antenna coil on an electrical wave signal receiving side.