Software determination of LED brightness and exposure
First Claim
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1. An image capture device, comprising:
- an illumination source;
a thermal model of said illumination source that determines a temperature of said illumination source;
a light output model of said illumination source that determines a light output of said illumination source from said temperature; and
, an exposure adjustment that is changed to compensate for changes in said illumination source as indicated by said model output.
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Abstract
The junction temperature of an LED is determined. This result is used to determine an initial brightness value of the LED. The initial brightness value is derated by a long-term degradation amount that is determined using a stored indication of the lifetime total on time. The derated brightness value is used to determine an exposure for a capture system. The junction temperature is determined by measuring the ambient temperature and then keeping a running junction temperature determined from the on and off times.
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Citations
26 Claims
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1. An image capture device, comprising:
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an illumination source;
a thermal model of said illumination source that determines a temperature of said illumination source;
a light output model of said illumination source that determines a light output of said illumination source from said temperature; and
,an exposure adjustment that is changed to compensate for changes in said illumination source as indicated by said model output. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of compensating for changes in an illumination source, comprising:
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determining a temperature of said illumination source;
determining a light output of said illumination source from said temperature; and
,adjusting an exposure to compensate for changes in said illumination source as indicated by said light output. - View Dependent Claims (9, 10, 11, 12)
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13. An article of manufacture comprising a program storage medium having computer readable program code means embodied therein for causing the adjustment of an exposure, the computer readable program code means in said article of manufacture comprising:
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computer readable program code means for causing a computer to determine an indication of a temperature of an illumination source;
computer readable program code means for causing a computer to determine an indication of brightness of said illumination source from said indication of said temperature; and
,computer readable program code means for causing said computer to adjust said exposure based on said indication of said illumination sources brightness. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. An image capture device, comprising:
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illumination means;
thermal modeling means, said thermal modeling means producing a thermal modeling means output that is indicative of said illumination means temperature;
brightness modeling means, said brightness modeling means producing a brightness modeling means output that is indicative of said illumination means brightness; and
,exposure adjustment means for changing and exposure to compensate for changes in said brightness of said illumination means as indicated by said brightness modeling means output. - View Dependent Claims (21, 22, 23, 24, 25, 26)
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Specification