Sensor array and illumination system for a large depth-of-field bar code scanner
First Claim
1. An optical system for a bar code scanner for reading a bar code tag, comprising:
- a focusing means having an optical axis;
illumination means for projecting a sheet of light along an object plane at a first acute angle with respect to a plane perpendicular to the optical axis of the focusing means, for illuminating a strip on the bar code tag to be read; and
a detector array for receiving light reflected from the bar code tag, with a plurality of elements having a long axis and a short axis, positioned substantially in an image plane at a second acute angle with respect to a plane perpendicular to the optical axis of the focusing means, with the long axis of the elements arranged substantially perpendicular to the image of the illuminated strip of the bar code tag, the projection of the long axis of the elements of the detector array onto the object plane defining the working range of the optical system;
a plane through the focusing means perpendicular to the optical axis of the focusing means, the image plane and the object plane all intersecting along a line so that an image of the illuminated strip of the bar code tag is formed substantially in focus on the detector array when the bar code tag is within the working range of the optical system.
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Accused Products
Abstract
An improved sensor array and illumination scheme for a bar code scanner use a modified Scheimpflug arrangement optical system that simplifies signal processing. The preferred embodiment includes a detector array comprising a multi-element array of photosensors positioned in one Scheimpflug plane and an illumination beam in the form of a sheet of light along the other Scheimpflug plane. The detector array has a plurality of elements having a long axis and a short axis, with the long axis of the elements arranged substantially perpendicular to the image of the illuminated strip of the bar code tag. The projection of the long axis of the elements of the array onto the other Scheimpflug plane defines the working range of the optical system. So long as the bar code tag intersects the illumination beam within the working range, the image of the illuminated strip of the bar code tag will be substantially in focus across the elements of the detector array. Filtering allows substantially only the light from the illuminated strip to reach the detector array. Thus, substantially all of the light that reaches the detector array is useful signal, and all the output data from the array during a bar code scan is relevant. The output signal from the array can be processed with conventional digitizing and decoding circuitry with audio signal processing techniques.
172 Citations
42 Claims
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1. An optical system for a bar code scanner for reading a bar code tag, comprising:
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a focusing means having an optical axis; illumination means for projecting a sheet of light along an object plane at a first acute angle with respect to a plane perpendicular to the optical axis of the focusing means, for illuminating a strip on the bar code tag to be read; and a detector array for receiving light reflected from the bar code tag, with a plurality of elements having a long axis and a short axis, positioned substantially in an image plane at a second acute angle with respect to a plane perpendicular to the optical axis of the focusing means, with the long axis of the elements arranged substantially perpendicular to the image of the illuminated strip of the bar code tag, the projection of the long axis of the elements of the detector array onto the object plane defining the working range of the optical system; a plane through the focusing means perpendicular to the optical axis of the focusing means, the image plane and the object plane all intersecting along a line so that an image of the illuminated strip of the bar code tag is formed substantially in focus on the detector array when the bar code tag is within the working range of the optical system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An optical system of a bar code scanner for reading a bar code tag, comprising:
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a focusing means having an optical axis; illumination means for projecting a beam of light along a line in an object plane at a first acute angle with respect to a plane perpendicular to the optical axis of the focusing means for illuminating a spot on the bar code tag to be read; and a detector for receiving light reflected from the bar code tag, comprising an element having a long axis and a short axis, with the long axis positioned substantially along the intersection of an image plane at a second acute angle with respect to a plane perpendicular to the optical axis of the focusing means and a plane including the optical centerline of the focusing means and the line along which the illumination means projects the beam of light, the projection of the detector onto the object plane defining the working range of the optical system; a plane through the focusing means perpendicular to the optical axis of the focusing means, the image plane and the object plane all intersecting along a line so that the image of the illuminated spot on the bar code tag forms an image substantially in focus on the element when the bar code tag is within the working range of the optical system. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. An optical system for a bar code scanner for reading a bar code tag, comprising:
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a focusing means including an anamorphic element and having an optical axis; illumination means for projecting a sheet of light along an object plane at a first acute angle with respect to a plane perpendicular to the optical axis of the focusing means, for illuminating a strip on the bar code tag to be read; and a detector array for receiving light reflected from the bar code tag, with a plurality of elements positioned substantially in an image plane at a second acute angle with respect to a plane perpendicular to the optical axis of the focusing means, and arranged substantially perpendicular to the image of the illuminated strip of the bar code tag; the anamorphic element positioned to expand the projection of the detector array in a direction perpendicular to the illuminated strip, the projection of the detector array onto the object plane defining the working range of the optical system; a plane through the focusing means perpendicular to the optical axis of the focusing means, the image plane and the object plane all intersecting along a line so that an image of the illuminated strip of the bar code tag is formed substantially in focus on the detector array when the bar code tag is within the working range of the optical system.
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21. An optical system for measuring light reflected from an object, comprising:
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a focusing means having an optical axis; illumination means for projecting a sheet of light along an object plane at a first acute angle with respect to a plane perpendicular to the optical axis of the focusing means, for illuminating a strip on the object; and a detector array for receiving light reflected from the object, with a plurality of elements having a long axis and a short axis, positioned substantially in an object plane at a second acute angle with respect to a plane perpendicular to the optical axis of the focusing means, with the long axis of the elements arranged substantially perpendicular to the image of the illuminated strip on the object, the projection of the long axis of the elements of the detector array onto the object plane defining the working range of the optical system; a plane through the focusing means perpendicular to the optical axis of the focusing means, the image plane and the object plane all intersecting along a line so that an image of the illuminated strip on the object is formed substantially in focus on the detector array when the object is within the working range of the optical system. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31)
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32. An optical system for measuring light reflected from an object, comprising:
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a focusing means having an optical axis; illumination means for projecting a beam of light along a line in an object plane at a first acute angle with respect to a plane perpendicular to the optical axis of the focusing means for illuminating a spot on the object; and a detector for receiving light reflected from the object, comprising an element having a long axis and a short axis, with the long axis positioned substantially along the intersection of an image plane at a second acute angle with respect to a plane perpendicular to the optical axis of the focusing means and a plane including the optical centerline of the focusing means and the line along which the illumination means projects the beam of light, the projection of the detector onto the object plane defining the working range of the optical system; a plane through the focusing means perpendicular to the optical axis of the focusing means, the image plane and the object plane all intersecting along a line so that the image of the illuminated spot on the object forms an image substantially in focus on the element when the object is within the working range of the optical system. - View Dependent Claims (33, 34, 35, 36, 37, 38, 39)
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40. An optical system for measuring light reflected from an object, comprising:
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a focusing means including an anamorphic element and having an optical axis; illumination means for projecting a sheet of light along an object plane at a first acute angle with respect to a plane perpendicular to the optical axis of the focusing means, for illuminating a strip on the object to be read; and a detector array for receiving light reflected from the object, with a plurality of elements positioned substantially in an image plane at a second acute angle with respect to a plane perpendicular to the optical axis of the focusing means, and arranged substantially perpendicular to the image of the illuminated strip of the object; an anamorphic element positioned to expand the projection of the detector array in a direction perpendicular to the illuminated strip, the projection of the detector array onto the the object plane defining the working range of the optical system; a plane through the focusing means perpendicular to the optical axis of the focusing means, the image plane and the object plane all intersecting along a line so that an image of the illuminated strip of the object is formed substantially in focus on the detector array when the object is within the working range of the optical system.
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41. An optical system for a bar code scanner for reading a bar code tag comprising:
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a focusing means having an optical axis; a plurality of photodetectors, each having a long axis and a short axis lying in a plane at an acute angle with respect to a plane perpendicular to the optical axis of the focusing means, the photodetector plane and the focusing means plane intersecting along a line, the photodetectors being arranged side by side with the long axis of each photodetector being perpendicular to the line of intersection; a source of illumination projecting light in an illumination plane at a second acute angle with respect to a plane perpendicular to the optical axis of the focusing means, the illumination plane intersecting the photodetector plane and the focusing means plane along the same line; and means for spreading the light into a fan in the illumination plane.
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42. An optical system for a bar code scanner for reading a bar code tag comprising:
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a focusing means having an optical axis; at least one photodetector having a long axis and a short axis lying in a plane at an acute angle with respect to a plane perpendicular to the optical axis of the focusing means, the photodetector plane and the focusing means plane intersecting along a line, the long axis of the photodetector being perpendicular to the line of intersection; a source of illumination projecting light in an illumination plane at a second acute angle with respect to a plane perpendicular to the optical axis of the focusing means, the illumination plane intersecting the photodetector plane and the focusing means plane along the same line; and means for spreading the light into a fan in the illumination plane.
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Specification