Patent ID: 7216810

Claim:
A hand-supportable digital imaging-based bar code symbol reading device comprising: a hand-supportable housing; a multi-mode area 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 image sensing array for detecting imaged light reflected off the object during illumination operations in either (i) a narrow-area image capture mode in which a few central rows of pixels on the image sensing array are enabled, or (ii) a wide-area image capture mode in which substantially all rows of the image sensing array are enabled; a multi-mode LED-based illumination subsystem for producing narrow and wide area fields of narrow-band illumination within said FOV during narrow-area and wide-area image capture modes, respectively; an automatic object presence detection subsystem for producing an object detection field within said FOV and detecting objects present in said object detection field; 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 multi-mode LED-based illumination subsystem; an image capturing and buffering subsystem for capturing and buffering 2-D images detected by said multi-mode image formation and detection subsystem; an image-processing based bar code symbol reading subsystem for processing images captured and buffered by said image capturing and buffering subsystem and reading 1D and 2D bar code symbols represented in said images; an input/output subsystem for outputting processed image data to an external host system or other information receiving or responding device, and a system control subsystem for automatically controlling the operation of each said subsystem; wherein said automatic light exposure measurement and illumination control subsystem has a light collecting mirror and a photodiode arranged within said hand-supportable housing, wherein incident illumination is collected from a selected portion of the center of said FOV using said light collecting mirror, and then focused upon said photodiode for detection of the intensity of incident illumination and subsequent processing by said automatic light exposure measurement and illumination control subsystem, and wherein said automatic object presence detection subsystem automatically detects the presence of an object within said object detection field, and in response thereto, said system control subsystem enables said automatic light exposure measurement and illumination control subsystem to continuously measure the light exposure within said selected portion of the center of said FOV and automatically control the illumination produced by said multi-mode LED-based illumination subsystem so that the detected object is sufficiently illuminated and said multi-mode image formation and detection subsystem forms and detects good quality digital images of illuminated objects.