| 摘要 |
A digital imaging-based bar code symbol reading device employing an automatic light exposure measurement and illumination control subsystem having an optical axis which is coincident with the field of view (FOV) of a digital imaging area-type sensing array. The bar code symbol reading device including a system for detecting image light intensity reflected off an object in the FOV of the digital imaging-based bar code symbol reading device, having image formation optics including a beam splitter with a surface of a known reflection/transmission ratio. The image formation optics being arranged such that light reflected off of an object placed in the FOV of the digital imaging-based bar code symbol reading device is directed to the beam splitter whereby a portion of the return light being reflected from the image is directed towards the area-type sensing array during illumination operations in an image capture mode, and a portion of the return light being reflected from the images is transmitted through the beam splitter and focused upon a photodiode for detecting image light intensity and subsequent processing by an automatic light exposure measurement and illumination control subsystem, whereby said automatic light exposure measurement and illumination control subsystem controls illumination intensity produced by said illumination array subsystem. The digital imaging-based bar code symbol reading device further includes a system control subsystem for activating and controlling said subsystem components described above.
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