Non-contact power transmitting device having simplified self-oscillation feedback loop which interrupts power transmission when no load is present

• US 6,040,986 A
• Filed: 11/27/1998
• Issued: 03/21/2000
• Est. Priority Date: 12/09/1997
• Status: Expired due to Term

• Current Assignee: Hiroshi Sakamoto, Panasonic Electric Works Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Hiroshi Sakamoto, Matsushita Electric Works Ltd (Panasonic Holdings Corporation)
• Inventors: Sakamoto, Hiroshi, Abe, Hideaki
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US09/200,474
• Time in Patent Office: 480 Days
• Field of Search: 363/49, 363/21, 363/19, 363/20
• US Class Current: 363/21.02
• CPC Class Codes: H01F 2038/143 for signals
• CPC Class Codes: H01F 38/14 Inductive couplings for wireless supply or distribution of electric power using inductive coupling H02J50/10
• CPC Class Codes: H02J 50/12 of the resonant type
• CPC Class Codes: H02J 50/40 using two or more transmitting or receiving devices H02J50/50 takes precedence

Abstract

A power supplying section has a signal transmitting secondary coil which is not inductively coupled to a power transmitting primary coil, and actuates as a feedback coil of a switching element. A load section has a power transmitting secondary coil arranged so as to be confronted with the power transmitting primary coil when the load section is attached to the power supplying section, and also has a signal transmitting primary coil so as to be confronted with the signal transmitting secondary coil when the load section is attached to the power supplying section. When the load section is not attached to the power supplying section, the voltage is not induced in the signal transmitting secondary coil as the feedback coil, and the switching of the switching element is intermittently carried out.

Claims

1. A non-contact power transmitting device comprising:

(A) a power supplying section comprising;

a voltage source;

a start resistor connected to said voltage source;

a first capacitor connected to said voltage source;

a power transmitting primary coil;

a signal transmitting secondary coil which is not inductively coupled to said power transmitting primary coil; and

a switching element having a control terminal, wherein, said start resistor and said first capacitor apply a bias voltage to said control terminal of said switching element, and when the bias voltage applied to said control terminal becomes higher than a threshold voltage, said switching element switches a current from said voltage source to said power transmitting primary coil; and

(B) a load section comprising;

a power transmitting secondary coil; and

a signal transmitting primary coil being electrically and magnetically coupled to said power transmitting secondary coil,

wherein, when said load section is attached to said power supplying section, said power transmitting primary coil and said power transmitting secondary coil are magnetically coupled to each other, so that power is transmitted from said power supplying section to said load section by electromagnetic induction,

said signal transmitting secondary coil is magnetically coupled to said signal transmitting primary coil and electrically coupled to said control terminal as a feedback coil, and

said power transmitting primary coil, said power transmitting secondary coil, said signal transmitting primary coil, and said signal transmitting secondary coil form a feedback loop.

2. A non-contact power transmitting device according to claim 1, wherein the load section further includes a control circuit connected to said signal transmitting primary coil so as to control a voltage level induced in the signal transmitting primary coil.

3. A non-contact power transmitting device according to claim 1, wherein said power supplying section further includes a second capacitor connected in parallel to said power transmitting primary coil.

4. A non-contact power transmitting device according to claim 1, wherein said signal transmitting secondary coil is arranged outside of a magnetic-flux loop of said power transmitting primary coil, and said signal transmitting primary coil is arranged so as to be confronted with said signal transmitting secondary coil when said load section is attached to said power supplying section.

5. A non-contact power transmitting device according to claim 1, wherein said signal transmitting secondary coil is arranged inside of a magnetic-flux loop of said power transmitting primary coil, and said signal transmitting primary coil is arranged so as to be confronted with said signal transmitting secondary coil when said load section is attached to said power supplying section.