ILLUMINATION METHODS AND APPARATUS
Illumination methods and apparatus which are well suited for use with camera devices are described. The methods are well suited for use with a rolling shutter. In some embodiments, plurality of lighting elements are provided and controlled in a manner which is synchronized with operation of the rolling shutter. While the portion of an area which is being captured by the sensor is illuminated during the image capture process, lighting elements corresponding to portions of the area which are not being captured are not activated when the corresponding area portion is not being captured. In this manner the entire area is not illuminated at the same level for the entire image capture period and energy is used more efficiently as compared to devices which illuminate a complete area at a consistent illumination level for the full duration of an image capture time period in which a rolling shutter is used.
1 . A method of controlling an imaging device including multiple light emitting elements and at least one sensor with a rolling shutter, the method comprising:
operating the rolling shutter to control sequential capture of different image areas by an image sensor; and
operating different light emitting elements at different times depending on the image area being captured by said image sensor at a particular point in time.
2 . The method of claim 1 , wherein said rolling shutter is an electronic shutter that controls reading out of different portions of said image sensor at different times; and
wherein the light emitting element is a light source included in a lighting module which further includes:
a collimating lens positioned in front of said light source and for generating a beam of light from light output by said light source; and
at least a first beam flattening lens for flattening the beam of light in at least a first direction as it passes through the first beam flattening lens.
3 . The method of claim 1 , wherein said multiple light emitting elements includes an array of light emitting elements.
4 . The method of claim 3 , wherein operating different light emitting elements at different times depending on the image area being captured includes:
controlling different sets of light emitting elements in said array to emit light at different times.
5 . The method of claim 3 ,
wherein said light emitting elements include a plurality of sets of light emitting elements, each set of light emitting elements corresponding to different image areas which are captured by said sensor; and
wherein operating different light emitting elements at different times depending on the image area being captured includes:
operating a first set of light emitting elements corresponding to a first image area during a first period of time, determined based on the timing of said rolling shutter, during which a first portion of said sensor is exposed for image capture.
6 . The method of claim 5 , wherein operating different light emitting elements at different times depending on the image area being captured further includes:
operating a second set of light emitting elements corresponding to a second image area which is different from said first image area during a second period of time, determined based on the timing of said rolling shutter, during which a second portion of said sensor corresponding is being exposed for image capture.
7 . The method of claim 6 , wherein said first period of time includes at least a portion of time which does not overlap said second period of time.
8 . The method of claim 7 , wherein operating the second set of light emitting elements includes controlling said second set of light emitting elements to be off during said portion of time included in said first period of time which does not overlap said second period of time.
9 . The method of claim 8 , wherein operating different light emitting elements at different times depending on the image area being captured by said image sensor at a particular point in time includes:
determining when said first and second set of light emitting elements are to be on based on an exposure setting and a speed of said rolling shutter.
10 . The method of claim 9 , wherein different sets of light emitting elements in said plurality of light emitting elements are covered with different lenses, the method further comprising:
determining which sets of light emitting elements to use based on an effective focal length setting being used by said imaging device for image capture.
11 . The method of claim 10 , wherein said focal length is user selectable, the method further comprising:
determining the focal length from a user setting prior to determining which set of light emitting elements to use.
12 . The method of claim 11 , wherein said focal length is set by a user via a zoom control input.
13 . A camera device comprising:
a rolling shutter;
at least one sensor;
a plurality of light emitting elements; and
a light control element configured to control said light emitting elements in a synchronized manner with operation of said rolling shutter.
14 . The camera device of claim 13 ,
wherein said rolling shutter is an electronic shutter that controls reading out of different portions of said image sensor at different times.
15 . The camera device of claim 14 , wherein said multiple light emitting elements includes an array of light emitting elements.
16 . The camera device of claim 15 , wherein said light control device is configured to control different sets of light emitting elements in said array to emit light at different times in a manner that is synchronized with the timing of said rolling shutter.
17 . The camera device of claim 15 ,
wherein said light emitting elements include a plurality of sets of light emitting elements, each set of light emitting elements corresponding to a different image area which is captured by a different portion of said sensor.
18 . The camera device of claim 15 , wherein said light control device is configured to control a first set of light emitting elements corresponding to a first image area to output light during a first time period, said first time period being determined based on the timing of said rolling shutter and being a period of time during which a first portion of said sensor is exposed for image capture.
19 . The camera device of claim 17 , wherein different sets of light emitting elements in said plurality of light emitting elements are covered with different lenses.
20 . The camera device of claim 19 , wherein said light control device is further configured to:
determine which sets of light emitting elements to use based on an effective focal length setting being used by said camera device.