Welch Allyn, Inc.

Welch Allyn Data Collection, Inc.

Charles M Hammond

William H Havens

Andrew Longacre, Jr

Robert J Wood

Robert J Hennick

John M Pidhirny

Robert C Hinkley

Jeffrey B Powers

Harry R McKinley

Joseph J Morabito

Tanya A Onori

Briefly stated, the operating depth of field for a bar code scanner, preferably a laser scanner, is increased by placing a cubic phase mask (CPM) in the scanning beam. The masked beam is then scanned and reflected off a bar code and received by a photodetector. The received signal is then processed to recover the original unperturbed representation of the bar code pattern. The processed signal has an increased depth of field over an unmasked scanner signal.

Method and apparatus for extending operating range of bar code scanner

The operating depth of field for a bar code scanner, preferably a laser scanner, is increased by placing a cubic phase mask (CPM) in the scanning beam. The masked beam is then scanned and reflected off a bar code and received by a photodetector. The received signal is then processed to recover the original unperturbed representation of the bar code pattern. The processed signal has an increased depth of field over an unmasked scanner signal.

A low profile optical unit for use in a 2D bar code reader. A vertically disposed light redirecting panel having contoured reflective openings therein is mounted in the front of the unit and an LED behind the panel. Light emitting diodes for illuminating a target are mounted on the LED board behind the contour openings whereby direct light and reflected light illuminates a target. An imager housing is mounted on the back of the LED board and contains a recess that passes through the back of the housing and a lens barrel that extends forward through holes provided in the LED board and the light redirecting panel. An imager board is secured to the back of the housing which holds a 2D imager that is contained within the housing recess. Circuitry for generating image data signals is mounted on the back of the imager board. A lens holder is threadably mounted in the lens barrel which contains a lens system having a short back focal length for focusing a target image on the imager.

Imaging and illumination optics assembly

An array of reflectors is arranged to approximately match the arrangement of a two-dimensional array of LEDs such as used in a 2-D bar code scanner. Each reflector has at least one reflecting wall for reflecting light from a respective LED, thus increasing the amount of LED light illuminating the target.

Illuminating assembly for use with bar code readers

There is provided a system of detecting mark-sense indicia wherein the images of a light source and the region of sensitivity of a light sensor are substantially coaxial, coplanar, and coextensive throughout the working depth of field. This system is insensitive to the laminate and the diffusion effects. A light source is aimed at a beam splitter that diverts a portion of the light beam through optics that focus the light on a reflective target containing a bar code symbol to be scanned. The reflected beam is returned through the optics and the beam splitter, and a portion of the reflected beam is conducted to a light sensor. In this manner, the light path from the detector to the optical sensor is split twice by the beam splitter. The optics are configured so that the light beams that define the field of illumination and the region of sensitivity and which pass between the optics and the target are congruent, having identical optical axes and angles of divergence.

Intimate source and detector and apparatus employing same

There is provided an integrated semiconductor source-detector matrix in which solid state photonic diodes are configured as LEDs, disposed on a substrate and coupled to electronic circuits so that the diodes can be individually driven to emit light or to detect light as may be desired. Providing an integrated matrix of light source (emitter) and light sensor units disposed in close proximity results in each unit having nearly coextensive fields of view and illumination. Apparatus, such as bar code and optical readers utilizing such a matrix are shown, and are insensitive to the diffusion and laminate effects. In alternate embodiments the matrix is coupled to remote sensors or another similar matrix to provide optical communication and interchange devices having high bandwidth.

Integrated solid state light emitting and detecting array and apparatus

A scanner is provided for reading a target containing indicia, such as bar codes, which includes a means for directing the a light source so that it illuminates a target, a photodetector that generates an electrical signal indicative of the intensity of the detected light, a means for decoding the electrical signal to identify the presence of a target containing a region of relatively high reflectivity, and a means for modifying the level of illumination of the light source either from low to high upon recognition of said region of relatively high reflectivity or from high to low when some predetermined condition, such as the end of the indicia scan, or the passage of a time period without reading indicia, is met.

Reduced power scanner for reading indicia

A bar code detection circuit accepts as input the discretized analog output of a CCD array, and performs piecewise linear reconstruction to produces a continuous polylinear output signal. In the region of a bar/space transition, the output signal is a close approximation of the reflectance function of a bar code symbol convolved with the system transfer function of the bar code reader. Linear interpolation is performed in order to determine the offset of a given threshold value from an edge of the CCD analog output.

Analog reconstruction circuit and bar code reading apparatus employing

There is disclosed an simplified apparatus that enables optical scanners to achieve minimum field curvature and at the same time provide uniformly distributed light on an image sensor. A single element lens, preferably an aspherical lens made of a plastic material is combined with an aperture stop. The combination is capable of reducing lens aberrations and minimizing image field curvature for an object plane that contains indicia to be scanned or read. A suitably demagnified image of the indicia is focused onto an image sensor such as a CCD array. The spatial light distribution function in the image plane can be equalized by an attenuator, such as a neutral density filter or a slit, suitably configured to compensate for the reduced optical efficiency at large field angles. An aspherical lens containing a dye or a cold mirror can be used for limiting light transmission to a range of wavelengths.

Optical assembly and apparatus employing same using an aspherical lens

A method and apparatus are provided for detecting bar-space and space-bar transitions in a bar code symbol. A sequence of sparsely sampled analog signals from a photodetector in a bar code scanner is representative of the reflectance pattern of a symbol. Following initialization, a threshold, representing the value of the analog signal at a transition point, is derived from observed samples of the bars and spaces in the bar code symbol. Sampled reflectance information is accumulated as the symbol is scanned, and a program driven microprocessor calculates and repeatedly updates this threshold, using observed maxima and minima in the analog samples, and also referencing a binary output to determine whether a bar or space is currently being viewed. When the values of two successive analog samples bracket this threshold, then a bar-space or space-bar transition has occurred. Linear interpolation is performed on the two samples to determine the transition point and an offset from the first of the two samples. After a delay corresponding to this offset, the level of a binary output is changed. A bit serial binary output is thus produced, representative of the relative widths of bars and spaces.

Method of programmable digitization and bar code scanning apparatus

An optical reader is designed to be insensitive to specular reflection, particularly at tapered lead-in areas to the left and right of a coded record on a record member. The optical reader includes a photosensor that is oriented with its optical axis along the reader optical center line so as to be situated substantially perpendicular to the record member passing through a reader slot. There are upper and lower LEDs only, which are disposed respectively on opposite sides of the optical center line in a vertical plane. That is, the LEDs lie in a plane perpendicular to the path of a record member being swiped through the slot. In this way, no specular reflection at the lead-in areas will fall onto the photosensor. In addition, the effect of specular reflection occurring at areas of the record member in a plane perpendicular to its path of travel is reduced by a factor of two over an optical reader using a single LED.

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Skaneateles, NY, United States of America

Charles M Hammond