System for, and method of, controlling target illumination for an imaging reader
AssigneeSymbol Technologies, Inc.
InventorsVladimir Gurevich, David P. Goren
Life of this patent
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Abstract
An array of pixels of a solid-state imaging sensor having a rolling shutter is sequentially exposed to capture images from an illuminated target over successive frames for image capture by an imaging reader. The target is illuminated at a peak output power level for a fractional time period of a frame, and is not illuminated for at least a portion of a remaining time period of the frame for increased energy efficiency. Only a sub-array of the pixels is exposed during the fractional time period in which the target is being illuminated at the first output power level.
Claims18
A control system for an imaging reader having an illuminating light assembly for illuminating a target with illumination light, and a solid-state imaging sensor with a rolling shutter for sequentially exposing an array of pixels over an imaging field of view to capture images from the illuminated target over successive frames, the control system comprising:
- an illumination controller to control an output power level of the illumination light;
- and
- a main control in communication with the imaging sensor and the illumination controller, the main controller to:
- cause the imaging sensor to capture at least one previous image of the target in a previous frame that precedes at least one of the frames;
- detect an image brightness level of the previous image;
- cause the illuminating light assembly to operate at a first output power level for at least one fractional time interval of the at least one frame when the detected image brightness level is below a reference threshold level, and
- cause the illuminating light assembly to operate at a second output power level that is less than the first output power level for at least a portion of a remaining time period of the at least one frame, wherein:
- only a sub-array of the pixels of the array are exposed during the at least one fractional time interval;
- and
- the main controller is to cause the imaging sensor to capture a target image of the illuminated target.
A method of illuminating a target with an illumination light assembly, and of sequentially exposing an array of pixels of a solid-state imaging sensor having a rolling shutter over an imaging field of view to capture images from the illuminated target over successive frame for image capture by an imaging reader, the method comprising:
- controlling an output power of the illumination light assembly;
- operating the illumination light assembly at a first output power level for at least one fractional time interval of at least one of the frames;
- capturing at least one previous image of the target in a previous frame that precedes the at least one frame;
- detecting an image brightness level of the previous image, wherein the operating of the illumination light assembly at the first output power level for the at least one fractional time interval of the at least one frame is performed when the detected image brightness level is below a reference threshold level;
- operating the illumination light assembly at a second output power level that is less than the first output power level for at least a portion of a remaining time period of the at least one frame;
- exposing only a sub-array of the pixels of the array during the at least one fractional time interval;
- and
- capturing a target image of the illuminated target.
Dependencies are inferred from the claim text.