Magnetic chuck for convergence apparatus
A magnetic chuck ( 10 ) for temporarily holding an LCD imager ( 14 ) to a convergence device ( 12 ) during an alignment or convergence operation. A substrate ( 16 ) of the imager ( 14 ) is made of a magnetically permeable material. A knob ( 38 ) turns an armature assembly ( 22 ) such that in an on position 10 b a second magnetic flux path ( 46 b ) is allowed to permeate the substrate 16 thereby holding the imager ( 14 ) to a grip face 18 of the magnetic chuck ( 10 ). When the knob ( 28 ) is rotated to shunt flux through a first magnetic flux path ( 49 a ) through a pair of steel grip shoes ( 20 ), then the imager ( 14 ) is released form the grip face ( 18 ).
1. A holding apparatus for temporarily securing an imager having a ferro-magnetic component, said apparatus comprising:
a grip face adapted to abut said imager; and
a magnet disposed to selectively, magnetically engage said ferro-magnetic component of said imager by altering the magnetic field relative to the grip face.
2. The holding apparatus of claim 1 , wherein:
said magnet is a permanent magnet; and further comprising
a handle coupled to said magnet for rotating said magnet between an on position and an off position; and
a magnetically permeable shunt path for shunting magnetic flux therethrough when said magnet is rotated to said off position.
3. The holding apparatus of claim 2 , wherein:
said shunt path includes two ferro-magnetic blocks spaced apart from one another;
a portion of each of said blocks forms a portion of said grip face; and
each of said blocks at least partially encircles said magnet.
4. The holding apparatus of claim 3 , wherein:
said permanent magnet is shaped as a rectangular solid having at least one flat pole face.
5. The holding apparatus of claim 4 , and further including:
a cylindrical pole piece disposed adjacent said flat pole face.
6. The holding apparatus of claim 2 , wherein:
said magnet is held in an armature assembly.
7. The holding apparatus of claim 6 , wherein:
the armature assembly includes a non-magnetic shaft.
8. The holding apparatus of claim 6 , wherein:
said handle is affixed to the armature assembly such that the armature assembly can be manually rotated by the action of rotating said handle.
9. The holding apparatus of claim 6 , wherein:
said magnet is held within a shaft of the armature.
10. The holding apparatus of claim 9 , further comprising:
two cylindrical pole pieces, one of said pole pieces disposed adjacent a first pole face of said magnet, and the other of said pole pieces disposed adjacent a second pole face of said magnet.
11. The holding apparatus of claim 6 , wherein:
the imager is held by magnetic flux against a grip face when the armature assembly is rotated to an on position.
12. A magnetic chuck for holding an imager, comprising:
a non ferromagnetic housing;
two ferromagnetic blocks affixed to said housing; and
a magnet rotatably affixed between said blocks such that a magnetic field can selectively be routed through said blocks or between said blocks.
13. The magnetic chuck of claim 12 , and further including:
a grip face positioned such that when the magnetic field is routed between said blocks then the magnetic field passes across the grip face.
14. The magnetic chuck of claim 12 , and further including:
a knob for manually rotating said magnet.
15. The magnetic chuck of claim 12 , wherein:
said housing is made of aluminum.
16. The magnetic chuck of claim 12 , further comprising:
a magnetic armature at least partially surrounded by said blocks.
17. The magnetic chuck of claim 16 , wherein:
the armature includes a non ferromagnetic shaft at least partially enclosing said magnet.
18. The magnetic chuck of claim 17 , and further including:
at least one pole piece adjacent to said magnet.
19. The magnetic chuck of claim 18 , wherein:
the quantity of pole pieces is two.
20. The magnetic chuck of claim 12 , wherein:
said magnet flux from said magnet is routed through said blocks when said magnet is rotated to an off position.
21. A magnetic chuck for positioning an imager assembly, said magnetic chuck comprising:
a contact surface for engaging said imager assembly; and
means for selectively generating a magnetic field through said contact surface to attract said imager assembly to hold said imager assembly to said contact surface.
22. The magnetic chuck of claim 21 , wherein: said means for generating a magnetic field to attract said imager assembly includes:
a magnetic shunt path; and
means for selectively directing said magnetic field through said shunt path.
23. A method for mounting an imager assembly to another apparatus, said method comprising:
magnetically coupling said imager assembly to a positioning device;
positioning said imager with respect to said other apparatus with said positioning device;
fixing said imager with respect to said other apparatus; and
disengaging said imager from said positioning device.
24. The method of claim 23 , wherein:
said step of magnetically coupling said imager assembly to said positioning device includes directing a magnetic field to attract said imager assembly; and
said step of disengaging said imager includes redirecting said magnetic field through a shunt path.
25. The method of claim 23 , wherein:
said imager assembly includes a pixilated imaging device mounted to a front surface of a ferro-magnetic substrate; and
said step of magnetically coupling said imager assembly to a positioning device includes magnetically engaging a rear surface of said substrate.
26. The holding apparatus of claim 1 , wherein the selective magnetic engagement is provided by the ability to change at least one of the direction and strength of the magnetic field of said magnet.
27. A holding apparatus for temporarily securing an imager mounted to a front side of a substrate, said apparatus comprising:
a grip face adapted to abut a back side of said substrate; and
a magnet disposed to selectively, magnetically engage said back side of said substrate through said grip face by altering the magnetic field relative to the grip face.