Illumination methods and apparatus

Abstract

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.

What is claimed is: 
     
         1 . A method of controlling a system including a light source and at least a first image sensor, the method comprising:
 controlling sequential capture of different image areas by the first image sensor;   operating a light source to emit light; and   synchronizing changes in position of a movable mirror with capture of different image areas by the first image sensor, the changes in the position of the movable mirror directing light on to the different image areas as they are sequentially captured by the first image sensor.   
     
     
         2 . The method of  claim 1 , wherein said first image sensor includes a rolling shutter that is an electronic shutter that controls reading out of different portions of said image sensor at different times; and
 wherein the light source 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 light source includes an array of light emitting elements. 
     
     
         4 . The method of  claim 3 , further comprising:
 controlling different sets of light emitting elements in said array to emit light at different times.   
     
     
         5 . The method of  claim 1 , wherein said light source and said movable mirror are part of a lighting device which is external to a camera including said first image sensor. 
     
     
         6 . The method of  claim 5 , further comprising:
 operating the camera to output an image capture timing synchronization signal used to synchronize image capture and image area illumination.   
     
     
         7 . The method of  claim 6 , wherein said camera includes multiple sensors, said first image sensor being one of said multiple image sensors. 
     
     
         8 . The method of  claim 1 ,
 wherein said movable mirror is mounted on a hinge.   
     
     
         9 . The method of  claim 8 , wherein synchronizing changes in position of the movable mirror with capture of different image areas by the first image sensor includes:
 controlling movement of said hinge as a function of which area is being captured by the first image sensor at a given point in time.   
     
     
         10 . The method of  claim 1 , wherein said movable mirror is a multi-faced mirror. 
     
     
         11 . The method of  claim 10 ,
 wherein said movable mirror is mounted on a rotatable mount; and   wherein synchronizing changes in position of the movable mirror with capture of different image areas by the first image sensor includes:
 controlling rotation of said movable mirror as a function of which area is being captured by the first image sensor at a given point in time. 
   
     
     
         12 . A system comprising:
 at least a first image sensor;   a light source; and   a light control element configured to synchronize changes in position of a movable mirror with capture of different image areas by the first image sensor, the changes in the position of the movable mirror directing light on to the different image areas as they are sequentially captured by the first image sensor.   
     
     
         13 . The system of  claim 12 ,
 wherein said first image sensor includes an electronic shutter that controls reading out of different portions of said first image sensor at different times.   
     
     
         14 . The system of  claim 13 , wherein said light source includes an array of light emitting elements. 
     
     
         15 . The system of  claim 14 ,
 wherein said electronic shutter is a rolling shutter; and   wherein said light control device is configured to control different sets of light emitting elements in said array of light emitting elements to emit light at different times in a manner that is synchronized with the timing of said rolling shutter.   
     
     
         16 . The system of  claim 12 , wherein said light source and said movable mirror are part of a lighting device which is external to a camera including said first image sensor. 
     
     
         17 . The system of  claim 14 , further comprising:
 a hinge; and   wherein said movable mirror is mounted on said hinge.   
     
     
         18 . The system of  claim 17 , wherein said light control device controls movement of said hinge as a function of which area is being captured by the first image sensor at a given point in time. 
     
     
         19 . The system of  claim 14 , wherein said movable mirror is a multi-faced mirror. 
     
     
         20 . The system of  claim 19 , further comprising:
 a rotatable mount on which said movable mirror is mounted; and   wherein said light control device controls rotation of said movable mirror on said rotatable mount as a function of which area is being captured by the first image sensor at a given point in time.