Method and means for self-referencing and self-focusing a bar-code reader
First Claim
1. Apparatus for optically sensing contrasting marks disposed along an illuminated surface that is relatively movable with respect to the apparatus and that is positionable at variable distances from the apparatus, the apparatus comprising:
- lens means having an optical axis that is oriented to intersect the surface;
radiation sensor means positioned substantially along said optical axis for receiving radiation from the surface for producing output signals representative of radiation received thereby, said sensor means including a plurality of individual detectors disposed at various distances from the lens means; and
circuit means coupled to the sensor means for cyclically actuating the sensor means to respond to radiation reflected from the surface to produce an output that is indicative of the reflected radiation received by the sensor means at distances from such surface that vary cyclically through out-of-focus and in-focus distances for producing representations of the contrasting marks sensed in succession along the surface.
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Accused Products
Abstract
A scanning device and method for reading bar-code or other contrasting marks from a surface at variable distance from the scanning device operates by modulating the focal point of the optical system to yield pulse responses on detected code bars while in focus, and average background response levels from the bar-code surface while out of focus. Modulation of focal point of the optical system is achieved in selected ways such as by positioning optical elements using piezoelectric or electromagnetic drivers or liquid-crystal elements, or by staggering the positions along an optical axis of arrays of optical sensors, or of optical fibers coupled to the sensors.
107 Citations
15 Claims
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1. Apparatus for optically sensing contrasting marks disposed along an illuminated surface that is relatively movable with respect to the apparatus and that is positionable at variable distances from the apparatus, the apparatus comprising:
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lens means having an optical axis that is oriented to intersect the surface; radiation sensor means positioned substantially along said optical axis for receiving radiation from the surface for producing output signals representative of radiation received thereby, said sensor means including a plurality of individual detectors disposed at various distances from the lens means; and circuit means coupled to the sensor means for cyclically actuating the sensor means to respond to radiation reflected from the surface to produce an output that is indicative of the reflected radiation received by the sensor means at distances from such surface that vary cyclically through out-of-focus and in-focus distances for producing representations of the contrasting marks sensed in succession along the surface. - View Dependent Claims (2, 3)
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4. A method of sensing a bar code on a illuminated surface at varying distances therefrom, the method comprising the steps of:
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sensing the radiation reflected from the surface at distances which cyclically vary through focus and non-focus distances to produce an output indication of the relative levels of radiation reflected from the surface and sensed at the different distances; and producing an output representative of the bar code being sensed in response to the sensed radiation reflected from the surface varying from the level sensed at non-focus distances to the level sensed at the focus distance. - View Dependent Claims (5, 6, 7)
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8. Apparatus for optically sensing contrasting marks disposed along an illuminated surface that is relatively movable with respect to the apparatus and that is positioned at variable distances from the apparatus, the apparatus comprising:
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lens means having an optical axis that is oriented to intersect the surface; radiation sensor means positioned substantially along said optical axis for receiving radiation from the surface for producing output signals representative of radiation received thereby; - View Dependent Claims (10, 11, 12, 13, 14, 15)
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9. optical means interposed between said lens means and said radiation sensor means for cyclically altering the operative distance between the radiation sensor means and surface through the focal distance;
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circuit means coupled to the sensor means for selectively responding to radiation reflected from the surface to produce an output indicative of the reflected radiation received by the sensor means whether in focus or out of focus from such surface for producing representations of the contrasting marks sensed in succession along the surface.
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Specification