Method of low intensity lighting for high speed image capture
A system for synchronizing image capture and a light source has a first strobing light emitting diode (LED) array with a plurality of LEDs located to light an illumination area. The LED array has an on cycle during which the LED array is activated and an off cycle during which the LED array is inactivated. The system also has a camera located with a view of the illumination area. The camera has an image exposure that coincides with the on cycle of the strobing LED array.
1. A system for synchronizing image capture and a light source comprising:
a. a first strobing light emitting diode (LED) array comprising a plurality of LEDs located above a conveyor belt and configured to light an illumination area on the conveyor belt, the LED array having
i. an on cycle during which the LED array is activated; and
ii. an off cycle during which the LED array is inactivated,
wherein the strobing LED array is strobed at a fixed frequency to provide apparently constant human observable illumination of the illumination area during operation of the conveyor belt; and
b. a camera located with a view of the illumination area, the camera having an image exposure that coincides with the on cycle of the strobing LED array.
2. The system of claim 1 , wherein the frequency of the on cycle is at least 60 Hz.
3. The system of claim 1 , wherein the camera comprises a CCD sensor.
4. The system of claim 1 , wherein the camera comprises a global shutter.
5. The system of claim 1 , wherein the camera comprises a global shutter and CCD sensor.
6. The system of claim 1 , wherein a camera image exposure request occurs prior to the coincidence of the image exposure and the on cycle of the strobing LED array.
7. The system of claim 6 , wherein the camera image exposure request is initiated by a trigger.
8. The system of claim 6 , wherein the camera image exposure request is initiated by the decoder.
9. The system of claim 1 , wherein the camera comprises a global shutter CMOS imager.
10. A system for synchronizing an image capture and a light source for use in a barcode scanning tunnel comprising:
a. a scanning tunnel frame;
b. a conveyor belt for moving objects through the scanning tunnel frame;
c. a first strobing light array mounted on the scanning tunnel frame and positioned to illuminate an area of the conveyor belt, the strobing light array having
i. an on cycle during which the light array is activated, and
ii. an off cycle during which the light array is inactivated,
wherein the strobing light array is strobed at a fixed frequency to provide an apparently constant human observable illumination intensity on the illuminated conveyor belt area during operation of the conveyor belt; and
d. a camera located with a view of the illuminated conveyor belt area, the camera having an image exposure that coincides with the on cycle of the strobing light array.
11. The system of claim 10 , wherein the frequency of the on cycle is at least 60 Hz.
12. The scanning system of claim 10 , further comprising a trigger, wherein said trigger is an optically activated trigger that is activated by the presence of the object on the conveyor at a certain position.
13. The system of claim 10 , wherein the strobing light source comprises at least one light emitting diode.
14. The system of claim 10 , wherein the camera image exposure is initiated prior to the on cycle of the strobing light source.
15. The system of claim 14 , wherein the camera image exposure is initiated by a trigger.
16. The system of claim 15 , wherein the trigger is an optical sensor.