Data reader with hybrid auto focus system

Patent metadata

Field	Value
Publication number	US-10146975-B2
Application number	US-201615354247-A
Country	US
Kind code	B2
Filing date	Nov 17, 2016
Priority date	Nov 17, 2016
Publication date	Dec 4, 2018
Grant date	Dec 4, 2018

Abstract

The present disclosure relates to data readers including an improved imaging system that optimizes active and passive autofocus techniques for improving data reading functions. In an example, the data reader initially uses active autofocus techniques to focus a lens system based on a measurement reading by a rangefinder and acquire an image of an item in the field-of-view of the data reader. The data reader includes a decoding engine operable to decode an optical code of the item using the acquired image. If the decoding engine is unable to decode the optical code using the active autofocus technique, the data reader alternates to a passive autofocus technique to alter the focus settings of the lens system and reattempt the decoding process.

First claim

The invention claimed is:

1. A data reader comprising:
a housing;
a lens system carried in the housing, the lens system including one or more lens elements;
an image sensor carried by the housing, the image sensor operable to acquire a set of images of an item in a field-of-view of the data reader, the item bearing an optical label; and
a hybrid autofocus system including both an active autofocus mode and a passive autofocus mode, wherein the hybrid autofocus system is operable to selectively alternate between the active autofocus mode and the passive autofocus mode, the hybrid autofocus system comprising:
a rangefinder operable to measure a distance between the data reader and the item in the field of view of the data reader;
a driver in operable communication with the lens system, the driver operable to adjust a focus setting of the lens system by moving at least one of the one or more lens elements;
a decoding engine operable to decode the optical label from the set of images acquired by the image sensor; and
a controller operable to determine whether the optical code is decodable or non-decodable from the set of images based on an output signal from the decoding engine,
wherein, when the hybrid autofocus system is in the active autofocus mode, the driver adjusts a focus setting of the lens element based in part on the distance measured by the rangefinder, and wherein the image sensor acquires the set of images of the item with the lens system at the focus setting, and wherein the decoding engine attempts to decode the optical label from the set of images acquired by the image sensor; and
wherein, when the controller determines that the optical code is non-decodable by the decoding engine, the controller initiates the passive autofocus mode whereat the controller is further operable to:
analyze at least two images from the set of images acquired by the image sensor and determine contrast measurements for each of the at least two images; and
identify in each of the at least two images one or more focal planes based on the determined contrast measurements, each of the one or more focal planes corresponding to a focus position of the lens system; and
wherein, the driver adjusts the lens system to the focus position corresponding with at least one of the one or more focal planes, without using the rangefinder, and wherein the decoding engine attempts further decoding with the lens system set at the focus position.

2. The data reader of claim 1 , further comprising a motion detection unit operable to detect a motion of the data reader, wherein the rangefinder measures the distance between the data reader and the item in response to the motion detection unit detecting a motion of the data reader.

3. The data reader of claim 2 , wherein the motion detection unit comprises an accelerometer.

4. The data reader of claim 2 , wherein the motion detection unit comprises an image analysis system operable to analyze a set of images acquired by the image sensor for detecting motion of the data reader.

5. The data reader of claim 2 , wherein the driver delays adjusting the focus setting of the lens element when the motion detection unit indicates that the data reader is moving at a movement speed exceeding a threshold movement speed.

6. The data reader of claim 1 , further comprising an input mechanism in operable communication with the image sensor, the input mechanism operable to acquire the image via the image sensor in response to activation of the input mechanism.

7. The data reader of claim 6 , wherein the rangefinder measures the distance to the item in advance of activation of the input mechanism.

8. The data reader of claim 6 , wherein the rangefinder measures the distance to the item subsequent to activation of the input mechanism.

9. The data reader of claim 1 , further comprising a gyroscope configured to measure an inclination angle of the data reader, the gyroscope in operable communication with the driver to adjust the focus setting of the lens element based in part on the inclination angle of the data reader.

10. The data reader of claim 1 , further comprising a memory storing a calibration factor for associating the distance measured by the rangefinder with the adjustment of the focus setting by the driver, wherein an adjustment amount of the focus setting of the lens element is based in part on the calibration factor.

Assignees

• Datalogic IP Tech Srl

Inventors

• Canini Federico
• Vonmetz Kurt
• Bruni Davide

Classifications

• G06K7/10722

  Photodetector array or CCD scanning · CPC title

• G06K7/1465

  using several successive scans of the optical code · CPC title

• G06K7/10811 Primary

  Focalisation · CPC title

• G06K7/10831

  Arrangement of optical elements, e.g. lenses, mirrors, prisms (optical elements per se G02B) · CPC title