MAGNETIC DIRECT DRIVE SHUTTER ACTUATION SYSTEM

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims an invention which was disclosed in a

United States provisional patent application filed November 15, 2006,

Serial No. 60/859,184, entitled "Magnetic Direct Drive Shutter

Actuation System". Priority benefit of the said United States provisional

application is hereby claimed, and the aforementioned application is

hereby incorporated herein by reference.

BACKGROUND AND SUMMARY

[0002] Most commercially-available electromagnetic shutters are

driven by linear solenoids. While readily available and inexpensive, they

are very inefficient shutter actuators. Inherently non-linear, they provide

much-reduced force at the beginning of pull-in (just when the shutter

requires maximum force to achieve high acceleration and short ac

tuition time). They provide very short stroke, typically requiring

troublesome lever mechanisms to match the longer stroke required by

the shutter drive mechanism. Furthermore, the short stroke often

requires tight manufacturing tolerance and/or custom alignment of

solenoid to drive linkage. At smallest sizes, solenoids provide very poor

power efficiency for given output force/stroke.

[0003] Rotary solenoids are also sometimes used for shutter drive. And,

while these sometimes contain non-linear helical ramps to smooth out

the force/distance curve, they still have disadvantages in cost, energy

efficiency, and size.

[0004] DC motor actuators have occasionally been used. While they

offer more linear force/torque output and better power efficiency, they

still have several disadvantages. Their size/shape configuration is not

well matched to the low-profile donut-shaped space envelope

requirements of an optical shutter. Size trade-offs (tiny motors) reduce

power efficiency. Power coupling drives are sometimes costly and/or

inefficient. Motor inertia slows the start/stop response. And, motor

brushes add reliability and debris concerns for this short-stroke

start/stop application.

[0005] Some proprietary electromagnetic shutter drives (i.e., Kodak)

use magnets and coils to drive a shutter. However, these all include an

iron core electromagnet. These have the disadvantage of higher

inductance of the coil assembly. And most of these designs have

magnet/pole cogging (requiring higher drive current just to overcome

magnet/pole attraction before actuator motion takes place).

[0006] Thus, there is a continuing need for new and improved shutter

actuation mechanisms and technology. I have, therefore, developed a

direct-driven shutter blade/rotor assembly where each shutter blade (1

or more) has moving magnet(s) directly coupled to blade motion and

driven by a coil-induced electromagnetic field. The resultant shutter

drive system, where multiple blades/rotors are driven by the

electromagnetic field of a single coil multiplies the flux shift through the

coil and lowers (I ² R=power) power consumption for any given total

force/acceleration requirement.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 provides a schematic diagram illustrating basic

principles of my invention.

[0008] FIG. 2 provides a schematic flux flow diagram (simplified/folded

to 2D).

[0009] FIG. 3 provides a perspective schematic diagram of an

exemplary embodiment in the form of a simplified partial cutaway view

showing internal components.

DESCRIPTION

[00010] As will be noted from review of the drawing figures, my

invention relies on electromagnets to drive a permanent magnet (or

magnets) in a relatively linear fashion, with the said permanent

magnet(s) serving as actuators for shutter blades. Magnets can be

directly mounted on the shutter blades or on a separate blade driving

mechanism, a blade ring, linking and driving multiple blades.

[00011] FIG. 1 provides a very basic schematic illustrating some of the

operating principles of my invention. As it shows, the direct-drive

shutter of my invention is based on at least one pair of electromagnetic

poles arranged to push and/or pull the North and/or South poles of a

permanent magnet 3 in a linear direction transverse to the magnetic

poles/flux 3A of magnet 3 and of the flux axes of the electromagnet

poles. In the schematic illustrated in FIG. 1, the electromagnet pair

could be seen as being IA and IB, IA and 2A, 2A and 2B, or IB and 2B.

In fact, all act together to accomplish the purposes of the invention.

However, it will be easiest to understand the invention by initially

discussing a single one of the alternatives for pole pairs mentioned.

[00012] Beginning with the first alternative discussed above, where IA

and IB are seen as a pairing of electromagnetic poles, it will be seen

that an electromagnetic coil 4 produces a magnetic flux (as illustrated

by arrows 5A) in opposite directions in E/M flux conductors 5 depending

on the direction of current produced by bipolar voltage drive 6. Flux

conductors 5 are arranged so that one pole IA of the pair of

electromagnetic poles IA, IB is north while the other pole is south.

Thus, where as illustrated in FIG. 1, the north magnetic pole of magnet

3 is proximate pole IA and its south magnetic pole is proximate pole IB,

it will be pulled in direction 6 when IA is the south pole of the

electromagnetic poles IA, IB and IB is the north pole of this pair of

electromagnetic poles. Likewise, it will be pushed in direction 7 when

IA is the north pole of the electromagnetic poles IA, IB and IB is the

south pole of this electromagnetic pair.

[00013] Alternately, pole pairs 2A and 2 B can be seen as performing

this same function. And, finally, pole pairs IA and 2A, or IB and 2B can

also be seen as being the means for forcing lateral movements in

directions 6 or 7 depending on the direction of current in coil 4 and,

hence, the direction 5A of the magnetic flux in and through E/M flux

conductors 5.

[00014] However, while any one of the aforesaid pole pairs could

accomplish the purposes of this invention, the force/movement

generated by the use of such pole pairs and the purposes of the

invention are greatly facilitated by the arrangement of poles illustrated

in FIG. 1, where all of the aforesaid magnetic pole pairings

simultaneously assist in moving magnet 3. This is accomplished by

arranging the system so that each electromagnetic pole has a polarity

opposite to that of the electromagnetic pole located on the other end of

the permanent magnet 3 in the same direction 6 or 7 as well as being

opposite to the polarity of an adjacent electromagnetic pole located at

the same end of the permanent magnet 3, but in the opposite direction 6

or 7.

[00015] Thus, pole 2A like pole IA is adjacent to the north pole of

permanent magnet 3 but located in direction 7 rather than direction 6,

and will be south when pole IA is north and north when pole IA is

south. Likewise, the portions of said flux conductors 5 driving said poles

2 A, 2 B are arranged such that pole 2 B (while being adjacent to the south

pole of permanent magnet 3 like pole IB, but located in direction 7), will

be south when IB is north and north when IB is south.

[00016] In FIG. 1, all of the pole pairings are simultaneously driven by

the same voltage drive 6, and the preferred result discussed in the

preceding paragraphs is achieved by arranging relevant portions of flux

conductors 5 driving said poles to accomplish this result. However, the

same result can be accomplished through the use of multiple coils and

other means. Thus, the particular single coil arrangement illustrated in

FIG. 1 should not be seen as limiting the possibilities inherent in the

inventive concept.

[00017] In view of the foregoing, the more exemplary and preferred

embodiment illustrated in FIG. 3 can be better understood. In this

embodiment, a first coil 11 drives an upper inside pole 1 IA and a lower

inside pole HB. A second coil 12 drives an upper outside pole 12A and

a lower outside pole 12B. In keeping with the principles discussed

with regard to FIG. 1, the polarity of pole 1 IA will be the same as that of

pole 12B and opposite to that of 12A and HB. Thus, (as in FIG. 1) the

direction of the magnetic flux through poles HA, HB, 12A, and 12B,

forces magnets 3 (in this particular embodiment) towards or away from

the central axis 30. This movement is then used to operate (open/close)

shutters 13 by virtue of the lever arm 15 and pivot rod 14 combination

by which each permanent magnet 3 is anchored to the shutter housing

and rigidly connected to said respective shutter(s) 13. With some

reduction in electromagnetic efficiency, the 4-pole arrangement shown

in the drawing figures can be replaced with a 2-pole arrangement which

is less efficient, but could be manufactured at a lower cost.

[00018] However, there could be various other combinations of the

features/systems described above (all using the basic principles of this

invention as applied to a shutter drive). Moreover, various of the above-

disclosed and other features and functions, or alternatives thereof, may

be desirably combined into many other different systems or applications.

[00019] Thus, as will be appreciated from review of this specification,

numerous variations can be made and/or produced without exceeding

the scope of the inventive concept. There are, therefore, a variety of

presently unforeseen or unanticipated alternatives, modifications,

variations or improvements therein which may be subsequently made by

those skilled in the art which are also intended to be encompassed by

this application and the claims that follow.