Hand-supportable imaging-based bar code symbol reader capable of exposing an automatically detected object to a field of narrow-band LED-based illumination only when substantially all rows of pixels in a CMOS image sensing array are in a state of integration

摘要

A hand-supportable digital imaging-based bar code symbol reader comprises: an automatic object presence detection subsystem; an image formation and detection subsystem employing a CMOS area-type image detection array; an LED-based illumination subsystem employing an LED illumination array to generate a field of narrow-band LED-based illumination within the FOV; an automatic light exposure measurement and illumination control subsystem employing LED illumination driver circuitry; an image capturing and buffering subsystem; an image-processing bar code symbol reading subsystem; an input/output subsystem; and a system control subsystem for controlling the subsystems. The automatic light exposure measurement and illumination control subsystem controls the LED illumination driver circuitry to expose the automatically detected object, to a field of narrow-band LED-based illumination only when substantially all rows of pixels in the CMOS image sensing array are in a state of integration, thereby enabling the image capturing and buffering subsystem to capture high quality digital images independent of the relative motion between the bar code symbol reader and the object.