Thin film electromagnet and switching device comprising it

• US 20050047010A1
• Filed: 08/15/2002
• Published: 03/03/2005
• Est. Priority Date: 08/16/2001
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ishiwata, Nobuyuki, Ohashi, Keishi, Honjo, Hiroaki, Saito, Shinsaku, Toba, Tamaki
• Granted Patent: US 7,042,319 B2
• Time in Patent Office: Days
• US Class Current: 335/6
• CPC Class Codes: H01F 2007/068 using printed circuit coils
• CPC Class Codes: H01F 7/08 with armatures
• CPC Class Codes: H01H 50/005 using micromechanics

Abstract

The present invention provided a thin-film electromagnet including a magnetic yoke and a thin-film coil, characterized in that the magnetic yoke is comprised of a first magnetic yoke and a second magnetic yoke making contact with the first magnetic yoke, the first magnetic yoke is located at a center of a winding of which the thin-film coil is comprised, and the second magnetic yoke is arranged above or below the thin-film coil such that the second magnetic yoke faces the thin-film coil, and overlaps at least a part of the thin-film coil.

Claims

1. A thin-film electromagnet comprising a magnetic yoke and a thin-film coil,

characterized in that said magnetic yoke is comprised of a first magnetic yoke and a second magnetic yoke making contact with said first magnetic yoke,

said first magnetic yoke is located at a center of a winding of which said thin-film coil is comprised, and

said second magnetic yoke is arranged above or below said thin-film coil such that said second magnetic yoke faces said thin-film coil, and overlaps at least a part of said thin-film coil.

2. The thin-film electromagnet as defined in claim 1, wherein said thin-film electromagnet has magnetic poles at a surface of said first magnetic yoke which surface is opposite to a surface at which said first and second magnetic yokes make contact with each other, and further at an outer surface of said second magnetic yoke.

3. The thin-film electromagnet as defined in claim 2, wherein said magnetic pole generated at said surface of said first magnetic yoke is out of a center of said winding of which said thin-film coil is comprised.

4. The thin-film electromagnet as defined in any one of claims 1 to 3, further comprising a substrate, wherein said first and second magnetic yokes are arranged on said substrate.

5. The thin-film electromagnet as defined in claim 4, wherein said substrate constitutes said second magnetic yoke.

6. The thin-film electromagnet as defined in any one of claims 1 to 5, further comprising an insulating layer formed on said first or second magnetic yoke, wherein said thin-film coil is formed on said insulating layer.

7. The thin-film electromagnet as defined in any one of claims 1 to 6, further comprising a protection layer covering said first magnetic yoke, said second magnetic yoke and said thin-film coil therewith, wherein said protection layer is planarized at a surface thereof, and said surface of said first magnetic yoke, constituting said magnetic pole, is exposed to a planarized surface of said protection layer.

8. The thin-film electromagnet as defined in any one of claims 1 to 7, wherein said first and second magnetic yokes have a thickness in the range of 0.1 micrometer to 200 micrometers both inclusive.

9. The thin-film electromagnet as defined in claim 8, wherein said first and second magnetic yokes have a thickness in the range of 1 micrometer to 50 micrometers both inclusive.

10. The thin-film electromagnet as defined in any one of claims 1 to 9, wherein said first magnetic yoke is arranged above said second magnetic yoke, and said first magnetic yoke is comprised of a central portion located at a center of said winding of which said thin-film coil is comprised, a body portion making contact above said central portion with said central portion, and extending in parallel with said second magnetic yoke in a direction in which said second magnetic yoke extends, and projecting portions upwardly projecting at opposite ends of said body portion.

12. A switching device comprising a thin-film electromagnet defined in any one of claims 1 to 10, and a swingable unit, wherein said swingable unit is comprised of a pillar, and a swinger supported on said pillar for making swing-movement about said pillar, and

switching is carried out by turning on and off electromagnetic force generated between said thin-film electromagnet and said swinger.

13. The switching device as set forth in claim 12, wherein said first magnetic yoke faces said swinger.

14. The switching device as set forth in claim 12 or 13, wherein said swinger is supported on said pillar with a spring being arranged therebetween.

15. The switching device as set forth in claim 14, wherein said spring is composed of amorphous metal.

16. The switching device as set forth in claim 14, wherein said spring is composed of shape memory metal.

17. The switching device as set forth in any one of claims 12 to 16, wherein said swinger has magnetic substance.

18. The switching device as set forth in claim 17, wherein said magnetic substance has remanent magnetism.

19. A switching device comprising:

a first thin-film electromagnet;

a substrate in which said first thin-film electromagnet is buried;

a first electrical contact formed on a surface of said substrate;

a swinger rotatable in a plane vertical to said substrate by virtue of magnetic force generated by said first thin-film electromagnet; and

a second electrical contact formed on said swinger such that said second electrical contact makes contact with said first electrical contact when said swinger rotates towards said substrate;

wherein said first thin-film electromagnet is comprised of a thin-film electromagnet defined in any one of claims 1 to 10.

20. The switching device as set forth in claim 19, wherein said first electrical contact is formed on a surface of said substrate above said first thing-film electromagnet in electrical insulation from said first thin-film electromagnet.

21. The switching device as set forth in claim 19, wherein said first electrical contact is formed on a surface of said substrate away from said first thin-film electromagnet, and said swinger rotates about an intermediate point between said first thin-film electromagnet and said first electrical contact.

22. A switching device comprising:

a first thin-film electromagnet;

a second thin-film electromagnet;

a substrate in which said first and second thin-film electromagnets are buried;

a first electrical contact formed on a surface of said substrate above said first thin-film electromagnet in electrical insulation from said first thin-film electromagnet;

a second electrical contact formed on a surface of said substrate above said second thin-film electromagnet in electrical insulation from said second thin-film electromagnet;

a swinger rotatable in a plane vertical to said substrate about an intermediate point between said first thin-film electromagnet and said second thin-film electromagnet;

a third electrical contact formed on said swinger such that said third electrical contact makes contact with said first electrical contact when said swinger rotates towards said first thin-film electromagnet; and

a fourth electrical contact formed on said swinger such that said fourth electrical contact makes contact with said second electrical contact when said swinger rotates towards said second thin-film electromagnet,

wherein each of said first and second thin-film electromagnets is comprised of a thin-film electromagnet defined in any one of claims 1 to 10.

23. The switching device as set forth in any one of claims 19 to 22, further comprising connectors formed on opposite ends of said swinger, and extensions extending in a direction in which said swinger extends and attached to said swinger through said connectors, wherein said third and fourth electrical contacts are formed on said extensions.

24. The switching device as set forth in any one of claims 12 to 18, wherein said swinger has a light-reflective surface.

25. A switching device comprising:

a first thin-film electromagnet;

a substrate in which said first thin-film electromagnet is buried; and

a swinger rotatable in a plane vertical to said substrate by virtue of magnetic force generated by said first thin-film electromagnet,

wherein said swinger has a light-reflective surface, and said first thin-film electromagnet is comprised of a thin-film electromagnet defined in any one of claims 1 to 10.

26. The switching device as set forth in claim 24 or 25, wherein said swinger is covered partially or wholly at a surface thereof with gold or silver.

27. The switching device as set forth in any one of claims 12 to 18, wherein said swinger has a mirror unit for reflecting light.

28. A switching device comprising:

a first thin-film electromagnet;

a substrate in which said first thin-film electromagnet is buried;

a swinger rotatable in a plane vertical to said substrate by virtue of magnetic force generated by said first thin-film electromagnet, and

a mirror unit mounted on said swinger for reflecting light,

wherein said first thin-film electromagnet is comprised of a thin-film electromagnet defined in any one of claims 1 to 10.

29. The switching device as set forth in claim 28, wherein said mirror unit is formed by forming a sacrifice layer on said swinger, forming a metal or insulating film on said sacrifice layer which film will make said mirror unit, patterning said metal or insulating film, and removing said sacrifice layer.

30. The switching device as set forth in any one of claims 19 to 29, further comprising a pair of pillars arranged facing each other outside said swinger in a width-wise direction of said swinger, and

a pair of springs mounted on said pillars and extending towards said swinger,

wherein said swinger is supported at its opposite edges in its width-wise direction by said springs arranged such that a line connecting said springs to each other passes a center of said swinger in its length-wise direction.

31. A switching device comprising a thin-film electromagnet defined in any one of claims 1 to 10, and a swingable unit,

wherein said swingable unit is comprised of a pillar, and a cantilever supported on said pillar for making swing-movement about said pillar, and

switching is carried out by turning on and off electromagnetic force generated between said thin-film electromagnet and a free end of said cantilever.

32. A method of fabricating a switching device defined in any one of claims 19 to 31, said method comprising:

the first step of forming said second magnetic yoke on a substrate;

the second step of forming an insulating layer on said second magnetic yoke for electrically insulating said second magnetic yoke and said thin-film coil from each other;

the third step of forming said thin-film coil on said insulating layer;

the fourth step of forming an insulating layer covering said thin-film coil therewith;

the fifth step of forming said first magnetic yoke on said second magnetic yoke;

the sixth step of forming a protection film entirely covering a resultant resulted from said fifth step;

the seventh step of planarizing said protection film such that said first magnetic yoke is exposed to a surface of said protection film;

the eighth step of forming an electrical contact on said protection layer;

the ninth step of forming a sacrifice layer on said protection layer, said sacrifice layer having a pattern in which openings are formed in predetermined areas;

the tenth step of filling said openings with a predetermined material to form a pillar by which said swinger is supported;

the eleventh step of forming said swinger on said sacrifice layer; and

the twelfth step of removing said sacrifice layer.

11. A method of fabricating a thin-film electromagnet comprising a magnetic yoke and a thin-film coil, said magnetic yoke being comprised of a first magnetic yoke and a second magnetic yoke making contact with said first magnetic yoke, said first magnetic yoke being located at a center of a winding of which said thin-film coil is comprised, said method comprising:

the first step of forming said second magnetic yoke on a substrate;

the second step of forming an insulating layer on said second magnetic yoke for electrically insulating said second magnetic yoke and said thin-film coil from each other;

the third step of forming said thin-film coil on said insulating layer;

the fourth step of forming an insulating layer covering said thin-film coil therewith;

the fifth step of forming said first magnetic yoke on said second magnetic yoke;

the sixth step of forming a protection film entirely covering a resultant resulted from said fifth step; and

the seventh step of planarizing said protection film such that said first magnetic yoke is exposed to a surface of said protection film.