WO2008060599A2

WO2008060599A2 - Magnetic direct drive shutter actuation system

Info

Publication number: WO2008060599A2
Application number: PCT/US2007/024005
Authority: WO
Inventors: David W. Durfee
Original assignee: Melles Griot, Inc.
Priority date: 2006-11-15
Filing date: 2007-11-15
Publication date: 2008-05-22
Also published as: WO2008060599A3

Abstract

This magnetic direct drive shutter actuation system for an optical shutter with an aperture and shutter blades has blades rigidly connected via a pivot to a permanent magnet or magnets. This magnet or magnets have magnetic axes parallel to the pivot. The magnet or magnets is/are moved so as to cause rotation of said pivot and thereby open or close said aperture by electromagnets peripheral to the aperture. In the preferred embodiment, the electromagnet(s) form a quadrapole.

Description

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 (I²R=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.

Claims

WHAT IS CLAIMED IS:

1. A magnetic direct drive shutter actuation system for an optical shutter having an aperture with at least one shutter blade, comprising: a) a blade having a connected end and a distal end with said connected end being operatively connected via a pivot to a periphery of said aperture such that rotation of said pivot in a first rotational direction will move the distal end of said blade away from said periphery so as to occlude said aperture and rotation of said pivot in a second rotational direction will move said distal end towards said periphery so as to expose said aperture; b) a magnet operatively connected to said pivot so that movement of said magnet in a first direction will cause rotation of said pivot in the first rotational direction and movement of said magnet in a second direction will cause rotation of said pivot in the second rotational direction; and c) at least one electromagnet having poles arranged peripherally of said aperture so as to move said magnet in the first direction when a magnetic flux generated by said electromagnet is in a first polar orientation, and move said magnet in the second direction when a magnetic flux generated by said electromagnet is in a second polar orientation.

2. The magnetic direct drive shutter actuation system of claim 1, wherein at least one of the operative connection of said blade to the pivot is a rigid connection to said pivot, the operative connection of said magnet to the pivot is a rigid connection to said pivot, and the operative connections of said blade to both the pivot and said magnet are rigid connections.

3. The magnetic direct drive shutter actuation system of claim 1, wherein said magnet has first and second magnetic poles, which poles define a magnetic axis intersecting said poles, and said magnetic axis is generally parallel to the pivot axis.

4. The magnetic direct drive shutter actuation system of claim 2, wherein said magnet has first and second magnetic poles, which poles define a magnetic axis intersecting said poles, and said magnetic axis is generally parallel to the pivot axis.

5. The magnetic direct drive shutter actuation system of claim 3, wherein said at least one electromagnet has electromagnetic poles defining at least one electromagnetic axis intersecting electromagnetic poles having opposite polarity and at least one of: said at least one electromagnetic axis is parallel to said magnetic axis, and said at least one electromagnetic axis is transverse to said magnetic axis.

6. The magnetic direct drive shutter actuation system of claim 4, wherein said at least one electromagnet has electromagnetic poles defining at least one electromagnetic axis intersecting electromagnetic poles having opposite polarity and at least one of: said at least one electromagnetic axis is parallel to said magnetic axis, and said at least one electromagnetic axis is transverse to said magnetic axis.

7. The magnetic direct drive shutter actuation system of claim 3, wherein said at least one electromagnet is a quadrapole electromagnet arranged so that it has a pair of electromagnetic poles adjacent each magnetic pole, with one of said pair being proximate said aperture and another of said pair being distal said aperture.

8. The magnetic direct drive shutter actuation system of claim 4, wherein said at least one electromagnet is a quadrapole electromagnet arranged so that it has a pair of electromagnetic poles adjacent each magnetic pole, with one of said pair being proximate said aperture and another of said pair being distal said aperture.

9. The magnetic direct drive shutter actuation system of claim 7, wherein at least one of: the electromagnetic pole adjacent the first magnetic pole and distal said aperture always has the same polarity as the electromagnetic pole adjacent the second magnetic pole and proximate said aperture, and the electromagnetic pole adjacent the second magnetic pole and distal said aperture always has the same polarity as the electromagnetic pole adjacent the first magnetic pole and proximate said aperture.

10. The magnetic direct drive shutter actuation system of claim 8, wherein at least one of: the electromagnetic pole adjacent the first magnetic pole and distal said aperture always has the same polarity as the electromagnetic pole adjacent the second magnetic pole and proximate said aperture, and the electromagnetic pole adjacent the second magnetic pole and distal said aperture always has the same polarity as the electromagnetic pole adjacent the first magnetic pole and proximate said aperture.

11. A magnetic direct drive shutter actuation system for an optical shutter having an aperture with at least one shutter blade, comprising: a) a blade having a connected end and a distal end with said connected end being operatively connected via a pivot to a periphery of said aperture such that rotation of said pivot in a first rotational direction will move the distal end of said blade away from said periphery so as to occlude said aperture and rotation of said pivot in a second rotational direction will move said distal end towards said periphery so as to expose said aperture; b) a magnet operatively connected to said pivot so that movement of said magnet in a first direction towards said aperture will cause rotation of said pivot in the first rotational direction and movement of said magnet in a second direction away from said aperture will cause rotation of said pivot in the second rotational direction; c) at least one electromagnet having poles arranged peripherally of said aperture so as to move said magnet in the first direction when a magnetic flux generated by said electromagnet is in a first polar orientation, and move said magnet in the second direction when a magnetic flux generated by said electromagnet is in a second polar orientation; d) wherein the operative connections of said blade to both the pivot and said magnet are rigid connections; and e) wherein said magnet has first and second magnetic poles, which poles define a magnetic axis intersecting said poles, and said magnetic axis is generally parallel to the pivot axis.

12. The magnetic direct drive shutter actuation system of claim 11, wherein said magnetic axis is spaced from said pivot axis.

13. The magnetic direct drive shutter actuation system of claim 11, wherein said first direction and said second direction are not parallel to said magnetic axis.

14. The magnetic direct drive shutter actuation system of claim 12, wherein said first direction and said second direction are not parallel to said magnetic axis.

15. The magnetic direct drive shutter actuation system of claim 13, wherein said at least one electromagnet has electromagnetic poles defining at least one electromagnetic axis intersecting electromagnetic poles having opposite polarity and at least one of: said at least one electromagnetic axis is parallel to said magnetic axis, and said at least one electromagnetic axis is transverse to said magnetic axis.

16. The magnetic direct drive shutter actuation system of claim 14, wherein said at least one electromagnet has electromagnetic poles defining at least one electromagnetic axis intersecting electromagnetic poles having opposite polarity and at least one of: said at least one electromagnetic axis is parallel to said magnetic axis, and said at least one electromagnetic axis is transverse to said magnetic axis.

17. The magnetic direct drive shutter actuation system of claim 13, wherein said at least one electromagnet is a quadrapole electromagnet arranged so that it has a pair of electromagnetic poles adjacent each magnetic pole, with one of said pair being proximate said aperture and another of said pair being distal said aperture.

18. The magnetic direct drive shutter actuation system of claim 14, wherein said at least one electromagnet is a quadrapole electromagnet arranged so that it has a pair of electromagnetic poles adjacent each magnetic pole, with one of said pair being proximate said aperture and another of said pair being distal said aperture.

19. The magnetic direct drive shutter actuation system of claim 17, wherein at least one of: the electromagnetic pole adjacent the first magnetic pole and distal said aperture always has the same polarity as the electromagnetic pole adjacent the second magnetic pole and proximate said aperture, and the electromagnetic pole adjacent the second magnetic pole and distal said aperture always has the same polarity as the electromagnetic pole adjacent the first magnetic pole and proximate said aperture.

20. The magnetic direct drive shutter actuation system of claim 18, wherein at least one of: the electromagnetic pole adjacent the first magnetic pole and distal said aperture always has the same polarity as the electromagnetic pole adjacent the second magnetic pole and proximate said aperture, and the electromagnetic pole adjacent the second magnetic pole and distal said aperture always has the same polarity as the electromagnetic pole adjacent the first magnetic pole and proximate said aperture.