Depth sensor based auto-focus system for an indicia scanner

• US 10,121,039 B2
• Filed: 10/02/2017
• Issued: 11/06/2018
• Est. Priority Date: 10/10/2014
• Status: Active Grant

• Current Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Original Assignee: Hand Held Products Incorporated (Honeywell International Inc.)
• Inventors: Todeschini, Erik, Jovanovski, Brian L., Bremer, Edward C.
• Primary Examiner(s): Vo, Tuyen K
• Application Number:
  US15/722,011
• Publication Number:
  US 20180025196A1
• Time in Patent Office: 400 Days
• Field of Search: 23546201, 23546214, 23546215, 23546225, 23546245, 23547201
• CPC Class Codes: G01S 17/08 for measuring distance only indirect measurement G01S17/46; active triangulation systems G01S17/48
• CPC Class Codes: G01S 17/86 Combinations of lidar systems with systems other than lidar, radar or sonar, e.g. with direction finders
• CPC Class Codes: G01S 17/894 3D imaging with simultaneous measurement of time-of-flight at a 2D array of receiver pixels, e.g. time-of-flight cameras or flash lidar
• CPC Class Codes: G06K 2007/10504 Data fields affixed to objects or articles
• CPC Class Codes: G06K 2007/10524 Hand-held scanners
• CPC Class Codes: G06K 7/10732 Light sources
• CPC Class Codes: G06K 7/10792 Special measures in relation to the object to be scanned
• CPC Class Codes: G06K 7/10801 Multidistance reading
• CPC Class Codes: G06K 7/10811 Focalisation
• CPC Class Codes: G06K 7/10881 constructional details of hand-held scanners
• CPC Class Codes: G06K 7/1426 Multi-level bar codes

Abstract

An indicia reading terminal has a three-dimensional depth sensor, a two dimensional image sensor, an autofocus lens assembly, and a processor. The three dimensional depth sensor captures a depth image of a field of view and create a depth map from the depth image, the depth map having one or more surface distances. The two dimensional image sensor receives incident light and capture an image therefrom. The autofocusing lens assembly is positioned proximate to the two dimensional image sensor such that the incident light passes through the autofocusing lens before reaching the two dimensional image sensor. The processor is communicatively coupled to the two dimensional image sensor, the three dimensional depth sensor, and the autofocusing lens assembly.

Claims

1. An indicia reading terminal comprising:

a three dimensional depth sensor for capturing a depth image of a field of view and determining distances from the indicia reading terminal to major surfaces in the depth image having areas greater than a predetermined threshold to create a depth map of the depth image, comprising calculating areas of the major surfaces and comparing the calculated areas to the predetermined threshold;

a two dimensional image sensor;

an autofocusing lens assembly positioned proximate to the two dimensional image sensor such that incident light passes through the autofocusing lens assembly before reaching the two dimensional image sensor; and

a processor communicatively coupled to the two dimensional image sensor, the three dimensional depth sensor, and the autofocusing lens assembly;

wherein the processor is configured to;

calculate optimal focal distances from the autofocusing lens assembly to each of the major surfaces;

based on the calculated optimal focal distances, focus the autofocusing lens assembly at one of the optimal focal distances;

capture an image with the two dimensional image sensor; and

decode an indicia in the captured image.

2. The indicia reading terminal of claim 1, wherein each surface distance corresponds to a distance between the indicia reading terminal and each plane present within the field of view that has an area greater than the predetermined threshold.

3. The indicia reading terminal of claim 2, wherein the processor is configured to predict optimal focal distances for each surface distance.

4. The indicia reading terminal of claim 3, wherein, based on the predicted optimal focal distances, the autofocusing lens assembly progressively adjusts to each of the predicted optimal focal distances.

5. The indicia reading terminal of claim 4, wherein the autofocusing lens assembly progressively adjusts to each of the predicted optimal focal distances starting with the optimal focal distance closest to the indicia reading terminal.

6. The indicia reading terminal of claim 4, wherein the two dimensional image sensor captures an image when the autofocusing lens assembly is focused at each of the predicted optimal focal distances.

7. The indicia reading terminal of claim 6, wherein the processor analyzes each captured image and determines if a decodable indicia is present.

8. The indicia reading terminal of claim 7, wherein the processor signals to the autofocusing lens assembly to stop progressively adjusting to the next predicted optimal focal distance when a decodable indicia is present in the captured image.

9. The indicia reading terminal of claim 6, wherein the processor is configured to predict an optimal exposure level for each predicted optimal focus distance.

10. The indicia reading terminal of claim 9, wherein the two dimensional image sensor captures the image at the predicted optimal focal distance using the predicted optimal exposure level.

11. A method, comprising:

capturing a first depth image of a field of view with a three dimensional depth sensor in an indicia reading terminal;

determining distances from the indicia reading terminal to major surfaces in the first depth image having areas greater than a predetermined threshold to create a depth map of the first depth image, comprising calculating areas of the major surfaces and comparing the calculated areas to the predetermined threshold;

calculating optimal focal distances from an autofocusing lens assembly in the indicia reading terminal to each of the major surfaces, wherein light passes through the autofocusing lens assembly to a two dimensional image sensor;

capturing a first image with the two dimensional image sensor when the autofocusing lens assembly is focused at one of the optimal focal distances; and

decoding an indicia in the captured first image.

12. The method of claim 11, comprising sequentially focusing the autofocusing lens assembly at each of the calculated optimal focal distances.

13. The method of claim 12, comprising stopping the sequential focusing of the autofocusing lens assembly when a decodable indicia is present in the captured image.

14. The method of claim 11, comprising capturing an image at each of the optimal focal distances with the two dimensional image sensor.

15. The method of claim 14, comprising analyzing each captured image for the presence of a decodable indicia.

16. The method of claim 15, comprising capturing a second depth image of the field of view if no decodable indicia is present in any of the captured images based on the first depth image.

17. The method of claim 11, comprising predicting an optimal exposure level for each predicted optimal focus distance.

18. The method of claim 17, wherein the two dimensional image sensor captures the first image using the predicted optimal exposure level.

19. A method, comprising:

capturing a first depth image of a field of view with a three dimensional depth sensor in an indicia reading terminal;

determining distances from the indicia reading terminal to major surfaces in the first depth image having areas greater than a predetermined threshold to create a depth map of the first depth image;

calculating optimal focal distances from an autofocusing lens assembly in the indicia reading terminal to each of the major surfaces, wherein light passes through the autofocusing lens assembly to a two dimensional image sensor;

capturing a first image with the two dimensional image sensor when the autofocusing lens assembly is focused at one of the optimal focal distances;

decoding an indicia in the captured first image; and

comparing the area of the major surface having the decodable indicia with an expected area value encoded in the decodable indicia.

20. The method of claim 19, comprising determining approximate dimensions of an item having the decodable indicia from the areas of the major surfaces in the depth map.