Optical reader with adaptive exposure control

An optical reader comprising:

• a common output bus;
• an imaging array comprising a plurality of pixels, each pixel connected to said common bus and comprising a photo-sensitive element and a pixel circuit connected to said photo-sensitive element;
• an address decoder outputting a plurality of pixel select signals, each of said pixel select signals connected to a different pixel, said address decoder asserting said pixel select signals in a repeating, uninterrupted sequence so as to generate a continuous stream of pixel data on said common bus;
• and
• an adaptive exposure control circuit, said adaptive exposure control circuit comprising at least one stand-alone photo-sensitive detector not used in said image array, said stand-alone photo-sensitive detector connected to a comparator, wherein said adaptive exposure control circuit controls overlapping exposure periods for each pixel based on a relative amount of light detected simultaneously by said stand-alone photo-sensitive detector and said imaging array.

An integrated optical reader comprising:

• an imaging array fabricated using a CMOS process and located on a CMOS chip, said imaging array comprising a plurality of individually accessible pixels;
• a clock generator outputting an imaging array clocking signal at a variable clock frequency, said imaging array clocking signal having a new clock pulse to initiate each new pixel readout and controlling a rate at which data from said individually accessible pixels is read out;
• and
• an adaptive exposure control circuit, said adaptive exposure control circuit adjusting an exposure time of said pixels by adjusting said variable clock frequency, said adaptive exposure control circuit fabricated using a CMOS process and located on said CMOS chip.

An integrated optical reader comprising:

• an imaging array fabricated using a CMOS process and located on a CMOS chip, said imaging array comprising a plurality of individually accessible pixels;
• means for generating a periodic reading cycle of fixed duration;
• a clock generator outputting a clocking signal, said clocking signal controlling read out of said individually accessible pixels at a constant rate once each reading cycle;
• a light measurement exposure circuit, said light measurement exposure circuit fabricated using a CMOS process and located on said CMOS chip;
• and
• means for regulating a duty cycle of pixel exposure time individually for each pixel in response to an amount of light simultaneously detected by said light exposure measurement circuit and said imaging array.

An integrated optical reader, comprising:

• an imaging array fabricated using a CMOS process and located on a CMOS chip, said imaging array comprising a plurality of individually accessible pixels:
• means for generating a periodic reading cycle of fixed duration;
• a clock generator outputting a clocking signal, said clocking signal controlling read out of said individually accessible pixels at a constant rate once each reading cycle;
• a light measurement exposure circuit, said light measurement exposure circuit fabricated using a CMOS process and located on said CMOS chip;
• and
• means for regulating a duty cycle of pixel exposure time individually for each pixel in response to an amount of light detected by said light exposure measurement circuit;
• wherein said means for regulating a duty cycle of pixel exposure time individually for each pixel comprises an exposure period delay calculator connected to said light exposure measurement circuit, said exposure period delay calculator generating once each reading cycle a variable exposure delay period inversely proportional to said amount of light detected by said light exposure measurement circuit and holding each pixel in a reset state for said variable exposure delay period at the start of the exposure period for each pixel.

An optical reader, comprising:

• a plurality of photosensitive pixels;
• a plurality of pixel control signals connected to said photosensitive pixels;
• a clock generator;
• a readout clock signal output from said clock generator and connected to said pixel control signals, said readout clock signal comprising a separate clock pulse to initiate selection of each pixel in a designated sequential order, whereby an exposure time for said photosensitive pixels is controlled;
• and
• an exposure control circuit receiving light collection information from at least one of said photosensitive pixels, said clock generator adjusting a frequency of said readout clock signal in response to said light collection information received by said exposure control circuit.

An optical reader, comprising:

• a plurality of photosensitive pixels;
• a plurality of pixel select signals, each pixel select signal connected to a different photosensitive pixel;
• a plurality of pixel reset signals, each pixel reset signal connected to a different photosensitive pixel, whereby assertion of a pixel select signal causes its corresponding photosensitive pixel to be read and assertion of a pixel reset signal while the photosensitive pixel is selected causes the photosensitive pixel to be reset and exposure of the photosensitive pixel to end, such that sequential assertion of said pixel select signals and said pixel reset signals provides a continuous and uninterrupted stream of pixel data in a series of repeating frames;
• and
• an exposure control circuit receiving light collection information from at least one of said photosensitive pixels, said exposure control circuit adjusting a frequency of said pixel select signals and of said pixel reset signals in response to said light collection information, so as to vary a readout rate of said plurality of photosensitive pixels in response to a level of light exposure indicated by said light collection information.

An optical reader, comprising:

• a plurality of photosensitive pixels, each of said photosensitive pixels capable of being separately selected for readout and separately reset;
• a plurality of pixel outputs from said photosensitive pixels;
• a common bus connected to said pixel outputs, said common bus receiving a continuous and uninterrupted stream of pixel data when said photosensitive pixels are sequentially selected;
• and
• an exposure control circuit connected to said plurality of photosensitive pixels by a plurality of pixel control signals to provide individual selection and reset of said photosensitive signals, said exposure control circuit varying a readout rate of said photosensitive pixels in response to a level of light exposure of at least one of said photosensitive pixels, said readout rate increasing in response to an increase in said level of light and decreasing in response to a decrease in said level of light.

A method of optical reading, comprising the steps of:

• collecting light incident upon a plurality of photosensitive pixels;
• controlling a light exposure time individually and separately for each photosensitive pixel by selectively asserting a reset signal associated with each photosensitive pixel;
• reading light collection data from said photosensitive pixels on to a common output bus, said light collection data for each photosensitive pixel being read on to the common output bus just prior to the assertion of the reset signal associated with the photosensitive pixel so as to generate, by sequentially reading said photosensitive pixels in a repetitive pattern, a continuous and uninterrupted stream of pixel data on said common output bus;
• and
• varying said exposure time in response to a level of light exposure from at least one of said photosensitive pixels, thereby varying a readout rate of light collection data on to the common output bus said readout rate increasing in response to an increase in said level of light and decreasing in response to a decrease in said level of light.