CONTACTLESS RECEIVER, RESONANT CIRCUIT, AND VARIABLE CAPACITANCE ELEMENT

• US 20100056098A1
• Filed: 08/24/2009
• Published: 03/04/2010
• Est. Priority Date: 08/29/2008
• Status: Active Grant

• Current Assignee: Dexerials Corporation, Sony Chemical & Information Device Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Habu, Kazutaka, Watanabe, Makoto, Kanno, Masayoshi, Yokota, Toshiaki
• Granted Patent: US 8,781,396 B2
• Time in Patent Office: Days
• US Class Current: 455/343.100
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H04B 5/0012 using capacitive coupling
• CPC Class Codes: H04B 5/22 Capacitive coupling

Abstract

A contactless receiver is provided with a receiving section and a rectification section. The receiving section has a resonant circuit including a resonant capacitor having a variable capacitance element formed with a ferroelectric material, a capacitance of the variable capacitance element changing according to a received voltage at a predetermined frequency, and a resonance coil connected to the resonant capacitor. The rectification section converts an alternating current voltage output from the receiving section into a direct current voltage.

Claims

1. A contactless receiver comprising:

a receiving section having a resonant circuit including a resonant capacitor having a variable capacitance element formed with a ferroelectric material, a capacitance of the variable capacitance element changing according to a received voltage at a predetermined frequency and a resonance coil connected to the resonant capacitor; and

a rectification section for converting an alternating current voltage output from the receiving section into a direct current voltage.

2. The contactless receiver according to claim 1, further comprising:

a signal processing section which operates with the direct current voltage output from the rectification section for demodulating received signals.

3. The contactless receiver according to claim 1, wherein

the variable capacitance element has a characteristic in which the capacitance of the variable capacitance element becomes smaller or larger when the received voltage becomes higher within a predetermined voltage range within a range in which the received voltage changes.

4. The contactless receiver according to claim 1, wherein

the received voltage corresponding to a maximum capacitance of the variable capacitance element is equal to or smaller than a minimum operating voltage of the signal processing section.

5. The contactless receiver according to claim 1, wherein

a relationship of C₂≦

C₁/(Δ

fd)² is satisfied,

where the capacitance of the resonant capacitor is C₁ when a resonance frequency of the resonant circuit is substantially the same as the predetermined frequency, and the capacitance of the resonant capacitor when the largest received voltage is received is C₂, and a detuning value of the resonant circuit corresponding to a relative value of the largest operating voltage of the signal processing section with respect to the largest received voltage is Δ

fd.

6. The contactless receiver according to claim 1, wherein

the resonant capacitor only includes the variable capacitance element.

7. The contactless receiver according to claim 1, wherein

the ferroelectric material is a ferroelectric material in which ionic polarization occurs.

8. A resonant circuit comprising:

a resonant capacitor including a variable capacitance element formed with a ferroelectric material, a capacitance of the variable capacitance element changing according to an input alternating current voltage; and

a resonance coil connected to the resonant capacitor.

9. A variable capacitance element comprising:

a ferroelectric layer formed with a ferroelectric material, a capacitance of the ferroelectric layer changing according to an input alternating current voltage, and the capacitance becoming smaller or larger when the alternating current voltage becomes higher within a predetermined voltage range within a range in which the alternating current voltage changes; and

two electrodes sandwiching the ferroelectric layer.