Dynamic focus calibration, such as dynamic focus calibration using an open-loop system in a bar code scanner
OwnerSerge Thuries, Jean-Louis Massieuinventors
Life of this patent
Estimating the term…
Abstract
A system and method for recalibrating a bar code scanner or other optical system is described. In some cases, the system dynamically adjusts the focal length of a lens assembly based on open-loop process, such as based on feedback related to a distance between the lens assembly and an imaged object. In some cases, the system dynamically adjusts the lens assembly in order to provide auto focusing or zoom adjustment
Claims29
A method of dynamically recalibrating a bar code reader, the method comprising:
- receiving a recalibration signal or an indication of an error in reading an image of a machine readable code imaged by the bar code reader using a lens assembly calibrated at a first focal length, wherein the bar code reader employs open-loop auto focus controls;
- measuring a distance between the machine readable code and a lens assembly in the bar code scanner, wherein the distance is measured with a range finder carried by the bar code scanner;
- determining a second focal length of the lens assembly that provides a better image of the machine readable code;
- and
- recalibrating the open-loop auto focus controls of the bar code reader using the determined second focal length and the measured distance.
A hand-held device configured to take an image of an object, comprising:
- a lens assembly having an adjustable focal length;
- a range finder, wherein the range finder determines a distance between the hand-held device and a position on a selected object;
- an operation monitoring component, wherein the operation monitoring component receives an adjustment signal and initiates an adjustment of the focal length;
- and
- a dynamic adjustment component coupled to the lens assembly and range finder, wherein the dynamic adjustment component adjusts the focal length of the lens assembly based on information received from the range finder and based on the received signal from the operation monitoring component.
A computer memory within an imaging device and containing a data structure, the data structure used to calibrate the imaging device, the data structure comprising:
- one or more entries relating distance from an object to be imaged with the device and a lens of the device and a focal length to be applied to the lens of the device, wherein the distance is measured by an open-loop control process and the focal length is determined by a closed-loop process.
A system for dynamically recalibrating a bar code reader, the method comprising:
- means for receiving an indication of an error in reading an image of a machine readable code imaged by the bar code reader using a lens assembly calibrated at a focal length;
- means for measuring a first distance and a second distance, wherein the first distance is a distance between a first position on a machine readable code and a lens assembly in the bar code reader and the second distance is a distance between a second position on a machine readable code and the lens assembly;
- means for determining an alternate focal length of the lens assembly that provides an adjusted image of the machine readable code;
- and
- recalibrating the bar code reader using the determined alternate focal length and the measured distances.
A machine readable symbol reader configured to image a machine readable symbol, comprising:
- a lens assembly having an adjustable focal length;
- an open-loop measurement component, wherein the open-loop measurement component determines a distance between the machine readable symbol reader and a position on a machine readable symbol;
- a focus adjustment component, wherein the focus adjustment component determines an adjusted focus of the lens assembly;
- and
- a dynamic adjustment component coupled to the lens assembly and open-loop measurement component, wherein the dynamic adjustment component adjusts the focal length of the lens assembly based on one or more determined distances and based on one or more focus adjustments.
Dependencies are inferred from the claim text.