Digital imaging-based bar code symbol reader employing an LED-based illumination subsystem driven by an automatic light exposure measurement and illumination control subsystem

A digital imaging-based bar code symbol reading device having a working range, and comprising:

• an image formation and detection subsystem having image formation optics for producing a field of view (FOV) upon an object to be imaged and an area-type image sensing array for detecting imaged light reflected off the object during illumination operations in an image-capture mode in which substantially all rows of said area-type image sensing array are enabled, and when substantially all rows of pixels in said area-type image sensing array are in a state of integration operation, automatically generating a first control activation signal;
• a light emitting diode (LED) based illumination subsystem for automatically producing LED-based illumination within said FOV from an LED illumination array;
• an automatic object presence detection subsystem for automatically producing an object detection field that spatially encompasses a substantiated portion of said FOV within the working range of said digital imaging-based bar code symbol reading device, and detecting the presence of an object within said FOV and generating said second control activation signal in response to such object presence detection;
• an automatic light exposure measurement and illumination control subsystem for automatically measuring the light exposure incident upon a central portion of said FOV, and controlling the operation of said LED illumination array, in response to the generation of both said first and second control activation signals, so as to produce LED-based illumination from said LED illumination array and illuminate said detected object therewith during object illumination and image capture operations;
• an image capturing and buffering subsystem for capturing and buffering a digital image of the illuminated object, formed and detected by said image formation and detection subsystem;
• an image-processing based bar code symbol reading subsystem for processing said digital image captured and buffered by said image capturing and buffering subsystem, and reading 1D and 2D bar code symbols graphically represented in said digital image;
• an input/output subsystem for outputting processed image data to an external host system or other information receiving or responding device;
• a system control subsystem for controlling and coordinating the operation of said subsystems;
• and
• a housing for containing said subsystems, and having a light transmission panel with an imaging window, through which said FOV extends, said LED-based illumination is projected, and light reflected and scattered off said object is transmitted.