Electronic circuit device

1. An electronic circuit device, comprising:

a board that is formed of at least one insulating base;

a patterned conductor that is formed on the at least one insulating base;

a transformer that is provided at the board, the transformer having:

a magnetic core;

a primary winding member, the primary winding member being configured with:

a primary winding that is an integrated part of the patterned conductor and that is provided at the board; and

a primary side element that is incorporated in and electrically connected to the primary winding, wherein the primary side element is directly electrically connected to the primary winding without an intervening connecting pattern portion provided therebetween; and

a secondary winding member, the secondary winding member being configured with:

a secondary winding that is an integrated part of the patterned conductor and that is provided at the board; and

a secondary side element that is incorporated in and electrically connected to the secondary winding, wherein the secondary side element is directly electrically connected to the secondary winding without an intervening connecting pattern portion provided therebetween,

wherein each of the primary winding and the secondary winding is wound around the magnetic core, and the primary winding and the secondary winding are magnetically coupled with each other via the magnetic core; and

a first current path that is an integrated part of the patterned conductor between an input terminal of the electronic circuit device and the primary winding member, the input terminal being provided on the board, wherein the first current path is located so as to perpendicularly abut the primary winding member so that a magnetic flux generated by an electric current flowing in the first current path does not cross the primary winding member.

2. The electronic circuit device according to claim 1 , wherein

the board has a first surface and a second surface opposite to the first surface, and

the primary winding is located on the first surface of the board, and the secondary winding is located on the second surface of the board.

3. The electronic circuit device according to claim 2 , wherein

parts of the primary and secondary windings are located on the board, and

at least one other part of either the primary winding or the secondary winding is further located in the board.

4. The electronic circuit device according to claim 2 , wherein

a second current path is an integrated part of the patterned conductor between an output terminal of the electronic circuit device and the secondary winding member, and the output terminal is located on the board, and

the second current path is located so as to perpendicularly abut the second winding member so that a magnetic flux generated by an electric current flowing in the second current path does not cross the secondary winding member.

5. The electronic circuit device according to claim 2 , wherein

at least one of the primary side and secondary side elements is a field effect transistor,

an inner shield layer is provided on an inside of the board, and

the inner shield layer is located under the field effect transistor.

6. The electronic circuit device according to claim 2 , wherein

a plurality of primary elements configure a primary side circuit, and a plurality of secondary elements configure a secondary side circuit, and

each of the primary and secondary side circuits is configured as one of a half bridge circuit and a full bridge circuit.

7. The electronic circuit device according to claim 1 , wherein

parts of the primary and secondary windings are located on the board, and

at least one other part of either the primary winding or the secondary winding is further located in the board.

8. The electronic circuit device according to claim 7 , wherein

a second current path is an integrated part of the patterned conductor between an output terminal of the electronic circuit device and the secondary winding member, and the output terminal is located on the board, and

the second current path is located so as to perpendicularly abut the second winding member so that a magnetic flux generated by an electric current flowing in the second current path does not cross the secondary winding member.

9. The electronic circuit device according to claim 7 , wherein

at least one of the primary side and secondary side elements is a field effect transistor,

an inner shield layer is provided on an inside of the board, and

the inner shield layer is located under the field effect transistor.

10. The electronic circuit device according to claim 7 , wherein

a plurality of primary elements configure a primary side circuit, and a plurality of secondary elements configure a secondary side circuit, and

each of the primary and secondary side circuits is configured as one of a half bridge circuit and a full bridge circuit.

11. The electronic circuit device according to claim 1 , wherein

the board has a first surface and a second surface opposite to the first surface,

the primary and secondary windings are entirely located in the board, and

the primary winding is located at a side of the first surface, and the secondary winding is located at a side of the second surface.

12. The electronic circuit device according to claim 11 , wherein

a second current path is an integrated part of the patterned conductor between an output terminal of the electronic circuit device and the secondary winding member, and the output terminal is located on the board, and

the second current path is located so as to perpendicularly abut the second winding member so that a magnetic flux generated by an electric current flowing in the second current path does not cross the secondary winding member.

13. The electronic circuit device according to claim 11 , wherein

at least one of the primary side and secondary side elements is a field effect transistor,

an inner shield layer is provided on an inside of the board, and

the inner shield layer is located under the field effect transistor.

14. The electronic circuit device according to claim 11 , wherein

a plurality of primary elements configure a primary side circuit, and a plurality of secondary elements configure a secondary side circuit, and

each of the primary and secondary side circuits is configured as one of a half bridge circuit and a full bridge circuit.

15. The electronic circuit device according to claim 1 , wherein

a second current path is an integrated part of the patterned conductor between an output terminal of the electronic circuit device and the secondary winding member, and the output terminal is located on the board, and

the second current path is located so as to perpendicularly abut the second winding member so that a magnetic flux generated by an electric current flowing in the second current path does not cross the secondary winding member.

16. The electronic circuit device according to claim 15 , wherein

at least one of the primary side and secondary side elements is a field effect transistor,

an inner shield layer is provided on an inside of the board, and

the inner shield layer is located under the field effect transistor.

17. The electronic circuit device according to claim 15 , wherein

a plurality of primary elements configure a primary side circuit, and a plurality of secondary elements configure a secondary side circuit, and

each of the primary and secondary side circuits is configured as one of a half bridge circuit and a full bridge circuit.

18. The electronic circuit device according to claim 1 , wherein

at least one of the primary side and secondary side elements is a field effect transistor,

an inner shield layer is provided on an inside of the board, and

the inner shield layer is located under the field effect transistor.

19. The electronic circuit device according to claim 18 , wherein

a plurality of primary elements configure a primary side circuit, and a plurality of secondary elements configure a secondary side circuit, and

each of the primary and secondary side circuits is configured as one of a half bridge circuit and a full bridge circuit.

20. The electronic circuit device according to claim 1 , wherein

a plurality of primary elements configure a primary side circuit, and a plurality of secondary elements configure a secondary side circuit, and

each of the primary and secondary side circuits is configured as one of a half bridge circuit and a full bridge circuit.