Varied intensity and/or infrared auxiliary illumination of surveillance area
First Claim
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1. Apparatus for illuminating the field of view of a surveillance camera, comprising:
- an infrared light source;
optics for coupling radiation emanating from said infrared light source to the field of view of a surveillance camera having a vertical frame rate; and
a source of power connected to said infrared light source for applying pulses of power, at adjustable power level(s), to said infrared light source, said source of power being operative to pulse the infrared light source, at a plurality of levels, in synchronization with the camera vertical frame rate;
wherein said source of power applies varying power with respect to time to said infrared light source; and
wherein said source of power comprises a plurality of switches, said switches being operated cyclically, one at a time, in a timed sequence to provide pulses of progressively increasing power levels to said infrared light source.
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Abstract
Infrared radiation from a light source such as a laser diode illuminates the field of view of a surveillance camera. The amount of illumination is varied in intervals, which may for example, be about 3/4 of a second, by varying the power applied to the light source. The radiation may emanate from optical fibers surrounding a camera lens, or through other ports. The power to the laser diode may be altered in response to background light sensed by a photo cell. A filter on the camera preferentially passes reflected illumination of the source while alternating background illumination.
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Citations
10 Claims
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1. Apparatus for illuminating the field of view of a surveillance camera, comprising:
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an infrared light source; optics for coupling radiation emanating from said infrared light source to the field of view of a surveillance camera having a vertical frame rate; and a source of power connected to said infrared light source for applying pulses of power, at adjustable power level(s), to said infrared light source, said source of power being operative to pulse the infrared light source, at a plurality of levels, in synchronization with the camera vertical frame rate; wherein said source of power applies varying power with respect to time to said infrared light source; and wherein said source of power comprises a plurality of switches, said switches being operated cyclically, one at a time, in a timed sequence to provide pulses of progressively increasing power levels to said infrared light source. - View Dependent Claims (2, 3, 4)
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- 5. A method of recording successive frames of images of subject in a surveillance field of view by means of a surveillance camera which method includes illuminating said field of view with a pulsed source of infrared illumination, synchronizing the pulse rate of said source of illumination with the camera vertical frame rate, and adjusting the intensity of illumination to distinguish subjects being recorded from the remaining field of view, and progressively increasing intensity of illumination on a cyclical basis.
Specification
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Current AssigneeNorthrop Grumman Systems Corporation (Northrop Grumman Corporation)
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Original AssigneeNorthrop Grumman Corporation
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InventorsJones, Ronald B., Lang, Paul D., Tranchita, Charles J.
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Primary Examiner(s)Tung, Bryan
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Assistant Examiner(s)AN, SHAWN S
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Application NumberUS08/918,362Time in Patent Office791 DaysField of Search348/143, 348/150, 348/164, 340/567, 340/541US Class Current348/143CPC Class CodesG08B 13/196 using television camerasG08B 13/19636 pertaining to the cameraH04N 23/20 for generating image signal...H04N 23/74 by influencing the scene br...H04N 5/33 Transforming infrared radia...
