Search Images Maps Play YouTube News Gmail Drive More »
Sign in
Screen reader users: click this link for accessible mode. Accessible mode has the same essential features but works better with your reader.

Patents

  1. Advanced Patent Search
Publication numberUS3772537 A
Publication typeGrant
Publication dateNov 13, 1973
Filing dateOct 27, 1972
Priority dateOct 27, 1972
Publication numberUS 3772537 A, US 3772537A, US-A-3772537, US3772537 A, US3772537A
InventorsR Clifford, J Moses
Original AssigneeTrw Inc
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Electrostatically actuated device
US 3772537 A
Abstract
An electrostatic device having a relatively thin and flexible electrode strip, such as a metal coated plastic film or metal foil, which is secured to and normally curls away from an electrode member and is caused to electrostatically unfurl along the member by impressing a voltage between the member and strip. The device is capable of varied uses and is described in connection with its use as a thermal control louver and a light valve or shutter.
Images(1)
Previous page
Next page
Description  (OCR text may contain errors)

United States Patent [191 Clifford et al.

[451 Nov. 13, 1973 ELECTROSTATICALLY ACTUATED DEVICE [75] Inventors: Richard P. Clifford, Newport Beach; James A. Moses, Torrance, both of Calif.

[73] Assignee: TRW Inc., Redondo Beach, Calif.

[22] Filed:

Oct. 27, 1972 [21] Appl. No.: 301,425

[52] 0.8. CI. 310/6, 317/262 E, 200/181 [51] Int. Cl. H02n H00 [58] Field of Search 117/93.4 NC, 93.4 R;

[56] References Cited UNITED STATES PATENTS 2,893,041 7/1959 Schafer 310/12 X 2,942,077 6/1960 Diesel 200/181 2,975,307 3/1961 Schroeder et al 310/6 3,273,301 9/1966 Anderson 317/262 E 3,325,709 6/1967 Anderson 317/262 E 3,616,135 10/1971 Tesainer et a1... 3,641,373 2/1972 Elkuch 310/6 OTHER PUBLICATIONS Byrnes, Electrostatic Fluid Pump IBM Tech Disclosure Bulletin, Vol. 11, N0. 4, 9/68.

Primary Examiner-D. F. Duggan Att0rney-Daniel T. Anderson et a1.

[57] ABSTRACT An electrostatic device having a relatively thin and flexible electrode strip, such as a metal coated plastic film or metal foil, which is secured to and normally curls away from an electrode member and is caused to electrostatically unfurl along the member by impressing a voltage between the member and strip. The device is capable of varied uses and is described in connection with its use as a thermal control louver and a light valve or shutter.

5 Claims, 3 Drawing Figures PATENTEDHUY 13 I976 HEAT SOURCE LIGHT SOURCE Fig. 2

ELECTROSTATICALLY ACTUATED DEVICE BACKGROUND OF THE INVENTION l. Field This invention relates generally to electrostatically actuated devices, and more particularly to an electrostatic device having a normally curled electrode strip which is caused to unfurl by electrostatic action.

2. Prior Art A wide variety of devices have been devised which utilize electrostatic forces to move a part from one position to another. A few of the prior art patents disclosing such devices are listed below: US. Pat. Nos. 2,568,824; 2,885,509; 2,885,511; 2,927,255; 2,931,954; 2,942,077; 3,553,364.

Most, if not all, of these and other electrostatic de vices which have been developed to date are designed for a specific use, such as a relay, light valve, etc.

SUMMARY OF THE INVENTION The present invention provides a novel electrostatic device capable of many diverse uses. This electrostatic device has a relatively thin and flexible electrode strip which is secured to and normally curls away from an electrode member. A voltage is impressed between the electrode member and strip in such a way that the resulting electrostatic attraction force between the member and strip causes the latter to unfurl along the member. In the particular electrostatic devices described, the electrode member is a plate and the electrode strip is a metal coated plastic film or a. metal foil. This strip is preformed to normally curl into a coil. The outer end of the coiled strip is secured to one side of the electrode plate with electrical insulation between the plate and strip and with the coil curling away from the plate. When the electrode plate and strip are electrified, the strip unfurls across the surface of the plate and then returns to its coiled configuration when the voltage is removed.

This electrostatic device is capable of many diverse uses. Two different devices are described. One is a thermal central louver. The other is a light valve or shutter.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a longitudinal section through a thennal DESCRIPTION OF THE PREFERRED EMBODIMENTS The electrostatic device or thermal control louver 10 of FIG. 1 has an electrode member 12 including a flat metal plate 13. The upper surface of this plate is coated with a dielectric film 14. Louver 10 has a second electrode 16 in the form of a relatively thin and elastically flexible strip which may comprise metal coated plastic film, such as aluminized Mylar, or a metal foil. This electrode strip is preformed to normally curl into a coil 18, as shown in full lines. The outer end 19 of the strip is adhesively bonded or otherwise secured to the upper coated surface of the electrode member 12 with the coil 18 curling away from the member.

Louver 10 may be utilized as either a controllable thermal energy radiator for regulating radiant heat transfer from a heat source below the electrode member 12 to a heat sink above the member, as shown in FIG. 1, or as a controllable thermal energy absorber for regulating radiant heat transfer from a heat source above the electrode member to a heat sink below the member. In the case of the radiator, the electrode member 12 has a high thermal emittance and the electrode strip 16 has a low thermal emittance. This low thermal emittance of the strip may be attained by making the strip from a material which has low thermal emittance or by coating the strip with a low emittance material. In the case of the thermal energy absorber, the electrode member 12 has a high thermal absorbance and the electrode strip 16 has a low thermal absorbance.

Louver 10 has an electrifying circuit 20. This circuit includes a d-c voltage source 22 having one terminal connected to the electrode plate 13 and its other terminal connected to the electrode strip 16. A switch 24 is provided for interrupting the circuit and a currentlimiting resistor 26 is connected in series with the battery.

Whenthe switch 24 is open, the electrode strip 16 remains in its solid line coiled configuration. Under these conditions, the strip uncovers the upper thermal radiating surface of the electrode member 12 and maximum radiant heat transfer occurs between the heat source and heat sink through the plate.

When the switch 24 is closed, the terminal voltage of the d-c source 22 is impressed between the-electrode plate 13 and strip 16. This voltage electrifies the plate and strip with opposite electrical polarity. The resulting electrostatic attraction force between the plate and strip causes the strip to unfurl across the electrode member, as indicated in broken lines in FIG. 1. The strip then covers the electrode member to reduce heat transfer between the heat source and .heat sink. Reopening the switch 24 removes the impressed voltage and hence the electrostatic attraction force. The elastic strain energy stored in the electrode strip in its unfurled condition causes the stripto recurl itself to its coiled configuration and thereby restore the radiant heat transfer to its original high value. If desired, the switch 24, when opened to interrupt the electrifying circuit 20, may complete a short circuit path 28 for shortcircuiting the electrode plate and strip to rapidly dissipate the charges on the plate and strip. Also, the d-c source 22 may be adjustable to permit unfurling of the strip to and retention of the strip in any selected partially unfurled position, so as to permit finer control of the radiant heat transferbetween the heat source and sink.

The electrostatic light valve or shutter of FIGS. 2 and 3 is similar to the thermal control louver just described except for replacement of the metal electrode plate 13 and dielectric film 14 of the louver by an electrode plate 102, dielectric film 104, and intervening electrically conductive film 106 which are transparent to the wavelength of the light to be controlled, and use of an electrode strip 108 which is opaque to such light. The terminals of the electrifying circuit 110 are connected to the electrode strip 108 and the conductive film 106.

When the circuit switch 112 is closed, the electrode strip 108 unfurls across the electrode plate 102 to block passage of light through the plate. Opening the said electrode member comprises a plate and said switch permits the strip to recurl to its coiled configuraelectrode strip comprises a thin sheet material such tion and permit light passage through the plate. It will as tal ated plastic film, metal foil or the like. be understood that the Strip 108 y not be totally 3. An electrostatic device according to claim 1 opaque to light but only to those wavelengths to the 5 wherein; Controlledsaid device is a thermal control louver; What is claimed as new in support of Letters Patent Said electrode member comprises a hermal energy v radiator having high thermal emittance; and

An electrostatlc devlce compnsmgz said electrode strip has low thermal emittance.

an electrode member; 4. An electrostatic device according to claim 1 a relatively thin and resiliently flexible electrode strip secured at one end to said electrode member and having its opposite end portion preformed to normally curl away from said electrode member into a coil;

means electrically insulating said electrode member and strip from one another; and

wherein:

said device is a thermal control louver; said electrode member comprises a thermal energy absorber having high thermal absorbance; and said electrode strip has low thermal absorbance. 5. An electrostatic device according to claim 1 means for impressing a voltage between said elecwherein:

trode member and strip to cause said coiled end Said device is a light Valve; portion of said strip to unfurl lon id mb said electrode member is transparent to light; and 2. An electrostatic device according to claim 1 said electrode strip is opaque to light.

wherein:

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2893041 *Aug 1, 1958Jul 7, 1959George SchaferWindshield wiper with magnetically actuated flexible blade
US2942077 *Oct 28, 1957Jun 21, 1960Erdco IncElectrostatic controls
US2975307 *Jan 2, 1958Mar 14, 1961IbmCapacitive prime mover
US3273301 *Aug 28, 1963Sep 20, 1966Grace W R & CoMethod and apparatus for wrapping and package produced
US3325709 *Jan 11, 1965Jun 13, 1967Grace W R & CoDevice for electrostatically transporting an unrestrained sheet of dielectric film material
US3616135 *Mar 21, 1969Oct 26, 1971Wilkinson Micahel CCarpetlike material
US3641373 *Oct 2, 1969Feb 8, 1972Proctor EtsElectrostatic system for generating periodical mechanical vibrations
Non-Patent Citations
Reference
1 *Byrnes, Electrostatic Fluid Pump IBM Tech Disclosure Bulletin, Vol. 11, No. 4, 9/68.
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US4224557 *Jul 10, 1978Sep 23, 1980Displaytek Corporation Of SankoControlling unit for A.C. driving an electrostatic device
US4987332 *Sep 29, 1989Jan 22, 1991Pentel Kabushiki KaishaRobot hand for electrostatically applying thin workpiece to mold
US5233459 *Mar 6, 1991Aug 3, 1993Massachusetts Institute Of TechnologyElectric display device
US5642015 *May 1, 1995Jun 24, 1997The University Of British ColumbiaElastomeric micro electro mechanical systems
US5681103 *Dec 4, 1995Oct 28, 1997Ford Global Technologies, Inc.Electrostatic shutter particularly for an automotive headlamp
US5784189 *Jul 2, 1993Jul 21, 1998Massachusetts Institute Of TechnologySpatial light modulator
US5829870 *Dec 4, 1995Nov 3, 1998Ford Global Technologies, Inc.Variable headlamp system for an automotive vehicle using an electrostatic shutter
US5959763 *Feb 26, 1998Sep 28, 1999Massachusetts Institute Of TechnologySpatial light modulator
US5977685 *Jun 3, 1996Nov 2, 1999Nitta CorporationPolyurethane elastomer actuator
US6057520 *Jun 30, 1999May 2, 2000McncArc resistant high voltage micromachined electrostatic switch
US6229683Jun 30, 1999May 8, 2001McncHigh voltage micromachined electrostatic switch
US6359374Nov 23, 1999Mar 19, 2002McncMiniature electrical relays using a piezoelectric thin film as an actuating element
US6373682Dec 15, 1999Apr 16, 2002McncElectrostatically controlled variable capacitor
US6377438Oct 23, 2000Apr 23, 2002McncHybrid microelectromechanical system tunable capacitor and associated fabrication methods
US6485273Sep 1, 2000Nov 26, 2002McncDistributed MEMS electrostatic pumping devices
US6586738Apr 13, 2001Jul 1, 2003McncElectromagnetic radiation detectors having a micromachined electrostatic chopper device
US6590267Sep 14, 2000Jul 8, 2003McncMicroelectromechanical flexible membrane electrostatic valve device and related fabrication methods
US6700309Jan 16, 2002Mar 2, 2004McncMiniature electrical relays using a piezoelectric thin film as an actuating element
US6731492May 6, 2002May 4, 2004Mcnc Research And Development InstituteOverdrive structures for flexible electrostatic switch
US6972889Jun 27, 2002Dec 6, 2005Research Triangle InstituteMems electrostatically actuated optical display device and associated arrays
US7026602May 29, 2003Apr 11, 2006Research Triangle InstituteElectromagnetic radiation detectors having a microelectromechanical shutter device
US7448412Jul 22, 2005Nov 11, 2008Afa Controls LlcMicrovalve assemblies and related structures and related methods
US7753072Jul 22, 2005Jul 13, 2010Afa Controls LlcValve assemblies including at least three chambers and related methods
US7946308Oct 7, 2008May 24, 2011Afa Controls LlcMethods of packaging valve chips and related valve assemblies
US8198974 *Apr 25, 2005Jun 12, 2012Research Triangle InstituteFlexible electrostatic actuator
US8330820 *Dec 5, 2008Dec 11, 2012Bae Systems Information And Electronic Systems Integration Inc.Fast electrostatic shutter and method of achieving offset compensation in infrared video imagers using fast shutters
US8562776Sep 12, 2012Oct 22, 2013Bae Systems Information And Electronics Systems Integration Inc.Fast electrostatic shutter and method of achieving offset compensation in infrared video imagers using fast shutters
US20100141768 *Dec 5, 2008Jun 10, 2010Bae Systems Information & Electronic Systems Integration, Inc.Fast electrostatic shutter and method of achieving offset compensation in infrared video imagers using fast shutters
EP0072062A2 *Jul 23, 1982Feb 16, 1983Gian Vieri NardiniExternally actuated light shielding curtains housed in the sealed space of double glazings
EP1178597A1 *Apr 12, 2000Feb 6, 2002NUNUPAROV, Martyn SergeevichElectrostatic devices for mechanical blocking
WO1989001183A1 *Jul 19, 1988Feb 9, 1989Battelle Memorial InstituteDevice for unrolling and rolling a roll of material in sheet form and use of said device
WO1989001217A1 *Jul 19, 1988Feb 9, 1989Battelle Memorial InstituteDevice for unrolling on a substrate a material in sheet form rolled elastically in a spiral and use of said device
WO2009128008A1 *Apr 10, 2009Oct 22, 2009Koninklijke Philips Electronics N.V.High quantum efficiency lighting device with light influencing element
Classifications
U.S. Classification310/309, 83/658, 361/233, 200/181, 83/451
International ClassificationE06B9/24, H02N1/00
Cooperative ClassificationH02N1/006, E06B9/24, G02B26/02
European ClassificationE06B9/24, H02N1/00B2, G02B26/02