Optical focusing device and method
First Claim
1. A hand held symbology reader comprising:
- a portable housing configured to be held by a user such that the user can manipulate the reader for purposes of aiming it at a symbology to be read;
a two-dimensional photodetector having an active area positioned in said housing at a predetermined location; and
an objective taking lens positioned with respect to said two-dimensional photodetector to image symbologies on said active area thereof, said objective taking lens including a plurality of stationary lens elements fixedly aligned along an optical axis and at least one focusing element that is rotatable about an axis offset with respect to said optical axis, said focusing element being moveable transversely with respect to said optical axis to change the focus of said objective taking lens between at least two focusing zones so that said objective taking lens can image both linear and matrix symbologies over working distances that at least partially overlap with respect to linear and matrix symbologies.
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Accused Products
Abstract
A hand held, omnidirectional symbology or bar code reader for imaging linear and two dimensional (matrix, maxi-code) bar codes over relatively long working distances. The reader includes an imaging system including a focusing objective taking lens and a two-dimensional photodetector that operate to form an image of a bar code in X and Y directions simultaneously and generate an electrical signal representative of the code for subsequent downstream processing which extracts information embedded in a bar code. Focusing is achieved via a rotating disk that carries a plurality of optical shims for different focus zones. A through-the-lens (TTL) targeting system is provided to visually assist the user in positioning the reader for a variety of code modalities to assure that a bar code will be captured within the field of view and be sharply imaged on the photodetector when the lens is focused. Two different forms of artificial illumination are provided to accommodate nearby codes that may be either specular or partially diffuse and more distant codes where the reflection characteristics have less impact on code contrast. Elements of the photodetector are used to assess available light levels and activate the artificial illumination system when ambient light levels are low. Ranging through the lens using elements of the photodetector is included to provide information to set the focus of the objective lens in one of many possible focusing zones. All of the reader'"'"'s components are housed in an ergonomically designed shell to reduce user repetitive stress injuries while providing access to a user interface and a protective cover for the reader'"'"'s various systems.
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Citations
23 Claims
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1. A hand held symbology reader comprising:
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a portable housing configured to be held by a user such that the user can manipulate the reader for purposes of aiming it at a symbology to be read; a two-dimensional photodetector having an active area positioned in said housing at a predetermined location; and an objective taking lens positioned with respect to said two-dimensional photodetector to image symbologies on said active area thereof, said objective taking lens including a plurality of stationary lens elements fixedly aligned along an optical axis and at least one focusing element that is rotatable about an axis offset with respect to said optical axis, said focusing element being moveable transversely with respect to said optical axis to change the focus of said objective taking lens between at least two focusing zones so that said objective taking lens can image both linear and matrix symbologies over working distances that at least partially overlap with respect to linear and matrix symbologies. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for forming an image of a symbology, said method comprising the steps of:
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aiming an objective taking lens and a two-dimensional photodetector having an active area positioned behind said objective taking lens by a predetermined distance at the symbology so that the symbology is located with the field of view of the objective taking lens and the two-dimensional photodetector; continuously rotating a focusing element such that focusing element moves transversely with respect to said optical axis of the objective taking lens to continuously change the focus of said objective taking lens between at least two focusing zones so that said objective taking lens can image both linear and matrix symbologies over working distances that at least partially overlap with respect to linear and matrix symbologies; forming a series of images of the symbology via the objective taking lens onto the two-dimensional photodetector as the focusing element rotates; determining the range separating the objective taking lens and the symbology; determining a best focusing zone of the focusing element that most sharply images the symbology in accordance with the range determined as the focusing element rotates; capturing an image of the symbology with the two-dimensional photodetector when the best focusing zone of the rotating focusing element is in alignment with the objective taking lens. - View Dependent Claims (21, 22, 23)
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Specification