Method of optimizing focus plane position of imaging scanner

摘要

A method includes the following: (1) projecting a light pattern towards a target object; (2) detecting light returned from the target object through an imaging lens arrangement with an imaging sensor to capture at least a first slit-frame-image and a second slit-frame-image; (3) determining an optimized position of the imaging lens arrangement; (4) detecting light returned from the target object with the imaging sensor to capture an image of a barcode when the imaging lens arrangement is maintained at the optimized position; and (5) processing the image of the barcode to decode the barcode. In the method, determining the optimized position includes processing at least the first slit-frame-image and the second slit-frame-image.

主权项

1. A method comprising:
projecting a light pattern towards a target object; detecting light reflected from the target object due to the light pattern through an imaging lens arrangement having a focus plane that is variable in object space with an imaging sensor to capture at least a first slit-frame-image and a second slit-frame-image, the imaging sensor having rows of photosensitive elements arranged in a matrix, wherein the average position of the focus plane of the imaging lens arrangement during the capture of the first slit-frame-image is different from the average position of the focus plane of the imaging lens arrangement during the capture of the second slit-frame-image, wherein each of the first slit-frame-image and the second slit-frame-image has pixels located in no more than 32 rows of photosensitive elements in the matrix, wherein said detecting light reflected from the target object due to the light pattern comprises changing the position of the focus plane of the imaging lens arrangement to make the average position of the focus plane of the imaging lens arrangement during the capture of the first slit-frame-image different from the average position of the focus plane of the imaging lens arrangement during the capture of the second slit-frame-image; determining an optimized position of the imaging lens arrangement, with said determining including processing at least the first slit-frame-image and the second slit-frame-image, wherein said determining the optimized position comprises comparing at least a first focus sharpness of the first slit-frame-image and a second focus sharpness of the second slit-frame-image; detecting light returned from the target object through the imaging lens arrangement with the imaging sensor to capture an image of a barcode during a main frame exposure time period, wherein the position of the focus plane of the imaging lens arrangement during at least part of said main frame exposure time period is maintained at the optimized position as previously determined; and processing the image of the barcode to decode the barcode.