US4896039A
Expired / Lapsed
US
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Active infrared motion detector and method for detecting movement
Assignee: Individual
•
Filing: 1987-12-31
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Granted: 1990-01-23
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Expires: 2007-12-31
Abstract
Abstract A miniature active infrared motion detector contains a self-heating temperature sensitive resistor, an electronic circuit to maintain temperature of that resistor at predetermined constant level which is higher than ambient temperature. The detector actively radiates thermal energy to environment and measures electric power required to generate that energy. This provides information about temperature variations in surrounding objects. The detector is also comprised of a focusing system, image distortion means and a threshold circuit. An optical system can be made of a curved Fresnel lens or curved mirror, such as parabolic, cylindrical, spherical, etc. which distributes thermal radiation over narrow or wide field of view, potentially up to 360°. The method of detecting movements is based on the use of a warm sensor whose temperature is maintained constant and above ambient.
Inventors
- 👤 Jacob Fraden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 14:21
CPC Classifications
G; G08; G08B; G08B13/00; G08B13/18; G08B13/181; G01; G01P; G01P13/00; G08B13/189; G08B13/19; G08B13/193; Y; Y10; Y10S; Y10S250/00; Y10S250/01
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
110 words
An active infrared radiation motion detector for detecting a moving object, said detector comprising: a support body; a first temperature sensitive self-heating resistive means capable of emitting thermal radiation in response to electric power through said resistive means, mounted on said support body for emitting said thermal radiation for radiating on a region which may include said object; a first electronic control circuit connected to said resistive means for maintaining the resistance of said resistive means at a predetermined value by adjusting electrical power through said resistive means, and for providing a signal indicative of change in said power, said change being indicative of modulation by movement of said object.
Claim 2
Dependent Claim
110 words
An active infrared radiation motion detector for detecting a moving object, said detector comprising: a support body; a first temperature sensitive self-heating resistive means capable of emitting thermal radiation in response to electric power through said resistive means, mounted on said support body for emitting said thermal radiation for radiating on a region which may include said object; a first electronic control circuit connected to said resistive means for maintaining the resistance of said resistive means at a predetermined value by adjusting electrical power through said resistive means, and for providing a signal indicative of change in said power, said change being indicative of modulation by movement of said object.
Claim 3
Dependent Claim
37 words
An active infrared radiation motion detector as described in claim 1, further comprising: means for focusing, located on said support body for focusing thermal radiation from said resistive means toward the region which may include said object.
Claim 4
Dependent Claim
44 words
An active infrared radiation motion detector as described in claim 2, further comprising: said means for focusing, comprising a plurality of individually focused lenses, arranged so that thermal radiation falling on said object in said region, from said lenses, changes as the object moves.
Claim 5
Dependent Claim
30 words
An active infrared radiation motion detector as described in claim 2, further comprising: said means for focusing comprising a reflector, having a high degree of reflectivity in the far infrared.
Claim 6
Dependent Claim
37 words
An active infrared radiation motion detector as described in claim 3, further comprising: said means for focusing comprising a Fresnel lens comprising a plurality of sections, where each section is capable of independent focusing of infrared radiation.
Claim 7
Dependent Claim
33 words
An active infrared radiation motion detector as described in claim 5, further comprising: said Fresnel lens being curved to distribute infrared radiation produced by said resistive means over a desired field of view.
Claim 8
Dependent Claim
27 words
An active infrared radiation motion detector as described in claim 3, further comprising: said resistive means being positioned within the focal plane of said means for focusing.
Claim 9
Dependent Claim
25 words
An active infrared radiation motion detector as described in claim 4, further comprising: said resistive means being positioned within the focal plane of said reflector.
Claim 10
Dependent Claim
22 words
An active infrared radiation motion detector as described in claim 1, further comprising: said temperature sensitive self-heating resistive means being a thermistor.
Claim 11
Dependent Claim
38 words
An active infrared radiation motion detector as described in claim 1, further comprising: image distortion means, located on said support body between said resistive means and said region, for passing spatially selective levels of said emitted thermal radiation.
Claim 12
Dependent Claim
42 words
An active infrared radiation motion detector as described in claim 10, further comprising: said image distortion means comprising a mask including a section having high attenuation for thermal radiation, and a section having low attenuation for thermal radiation passing through said mask.
Claim 13
Dependent Claim
43 words
An active infrared radiation motion detector as described in claim 2, further comprising: material having a low degree of emissivity in far infrared located over portions of said resistive means which are outside of the thermal radiation gathering area of the focusing means.
Claim 14
Dependent Claim
60 words
An active infrared radiation motion detector as described in claim 1, further comprising: a second temperature sensitive self-heating resistive means, and a second control circuit for maintaining said second resistive means at approximately equal temperature with said first self-heating resistive means by adjusting electrical power through said resistive means, and for providing a signal indicative of change in said power.
Claim 15
Dependent Claim
32 words
An active infrared radiation motion detector as described in claim 1, further comprising: said control circuit maintaining the temperature of said resistive means at a level above ambient temperature of said region.
Claim 16
Dependent Claim
35 words
An active infrared radiation motion detector as described in claim 14, further comprising: said control circuit maintaining the temperature of said resistive means at a level above the expected highest temperature of the moving object.
Claim 17
Dependent Claim
31 words
An active infrared radiation motion detector as described in claim 10, further comprising: said resistive means comprising a non uniform pattern for delivering spatially selective levels of said emitted thermal radiation.
Claim 18
Independent Claim
82 words
A method of active infrared radiation motion detection, for sensing a moving object whose temperature is different from that of ambient, said method comprising: pre-heating an electrically heated, thermal radiation emitting, sensing means to a temperature above ambient; maintaining the temperature of said sensing means at a constant level; measuring the power required to maintain the temperature of said sensing means at constant level; detecting variations exceeding a predetermined minimum in said power, said variations being indicative of movement of said object.
Claim 19
Independent Claim
82 words
A method of active infrared radiation motion detection, for sensing a moving object whose temperature is different from that of ambient, said method comprising: pre-heating an electrically heated, thermal radiation emitting, sensing means to a temperature above ambient; maintaining the temperature of said sensing means at a constant level; measuring the power required to maintain the temperature of said sensing means at constant level; detecting variations exceeding a predetermined minimum in said power, said variations being indicative of movement of said object.
Claim 20
Dependent Claim
27 words
A method of active infrared radiation motion detection, as described in claim 17, further comprising: directing thermal radiation from said sensor to surroundings by a focusing system.
Claim 21
Dependent Claim
92 words
A method of active infrared radiation motion detection, as described in claim 17, further comprising: said preheating of sensing means being preheating of a pair of temperature sensitive self-heating resistors to approximately equal temperatures, at a temperature above ambient; and said detecting-variations in said power, comprising comparing measured power required to maintain the temperature of each of said pair at a constant level, and detecting variations between the measured power for each of said pair, said variations being indicative of movement of said object, exclusive of common sources of ambient thermal interference.
Claim 22
Dependent Claim
27 words
A method of active infrared radiation motion detection, as defined in claim 17 comprising use of focusing system to direct thermal radiation from said sensor to surroundings;
Claim 23
Dependent Claim
22 words
A method of active infrared radiation motion detection, as defined in claim 17 comprising use of at least two said sensing means.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-01-22 | 1993-07-24 | 1994-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-22 | 1997-07-24 | 1998-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-22 | 2001-07-24 | 2002-01-23 | $7700.00 | Window Closed / Lapsed |