Fast vision system

Patent metadata

Field	Value
Publication number	US-10210362-B2
Application number	US-201514831054-A
Country	US
Kind code	B2
Filing date	Aug 20, 2015
Priority date	Dec 22, 2008
Publication date	Feb 19, 2019
Grant date	Feb 19, 2019

Abstract

A method and apparatus for performing a vision process using a camera having a multi-focus lens having a lens field of view where the lens can be set at different focus positions the method comprising the steps of positioning at least one of the camera and an item to be imaged so the lens field of view is directed at the item to be imaged, obtaining a plurality of images where each image is obtained with the lens focus at a different position and after each image is obtained, attempting to perform the machine vision process using the image irrespective of whether or not the lens was focused when the image was obtained.

First claim

To apprise the public of the scope of this invention, the following claims are made:

1. A system for performing a vision process using a camera having a variable-focus lens having a lens field of view where the lens can be set at different focus positions, the system comprising:
a processor programmed to perform the steps of: setting an
image-independent formation setting;
controlling the camera to obtain a subset of images at each of a plurality of different image-independent lens focus positions where the image-independent image formation setting is different for each of the images obtained at each image-independent lens focus position; and
after each image is obtained and while obtaining additional images, attempting to perform the vision process on the images;
wherein the vision process includes one of locating a symbol in obtained images and decoding a symbol in obtained images.

2. The system of claim 1 wherein the variable-focus lens has a range of different focus positions from a minimum focus position to a maximum focus position and wherein the processor is programmed to control the camera to obtain a plurality of images by obtaining images in a sequence where the focus position starts at one end of the range and incrementally steps through the range toward the maximum focus position.

3. The system of claim 1 wherein the variable-focus lens has a range of different focus positions from a minimum focus position to a maximum focus position and wherein the processor attempts to perform the vision process until one of (i)the vision process has been successfully completed for at least one of the images and (ii) the vision process has been attempted for images at each of the different focus positions.

4. The system of claim 1 wherein the processor is further programmed to perform the steps of using at least a subset of the images to determine one of that the lens is focused on the item and that the lens is unfocused on the item in the image and, where the lens is focused on the item in the image, ending the process after attempting to perform the machine vision process on the image corresponding to the focusedlens.

5. The system of claim 1 wherein the processor is further programmed to perform the steps of, when the lens is unfocused on the symbol to be imaged, using at least one of the obtained images to determine how to better focus the lens on the symbol to be imaged and adjusting the lens to better focus on the symbol to be imaged prior to obtaining another image.

6. The system of claim 1 wherein the image-independent image formation setting is at least one of light brightness, exposure duration and image sensor gain.

7. A system for performing a vision process using a camera having a variable-focus lens having a lens field of view where the lens can be set at different focus positions, the system comprising:
a processor programmed to perform the steps of: setting an
image-independent image formation setting;
obtaining a subset of images at each of a plurality of different lens focus positions where the image formation setting is different for each of the images obtained at each lens focus position; and
after each image is obtained and while obtaining additional images, attempting to perform the vision process on the images.

8. The system of claim 7 wherein the processor is further programmed to perform the steps of obtaining images at the maximum and the minimum lens focus positions.

9. The system of claim 7 wherein the processor is further programmed to perform the steps of obtaining images at different lens focus positions between the maximum and the minimum lens focus positions.

10. The system of claim 7 wherein the step of attempting to perform the machine vision process includes, when the machine vision process is successfully performed on at least one of the images, halting further image acquisition.

11. The system of claim 7 wherein the processor is further programmed to perform the steps of, when the machine vision process is successfully performed on at least one of the images, indicating that the machine vision process has been successfully completed.

12. The system of claim 7 wherein the variable-focus lens has a range of different focus positions from a minimum focus position to a maximum focus position and wherein the processor attempts to perform the vision process until one of (i) vision process has been successfully completed for at least one of the images and (ii) the vision process has been attempted for images at each of the different focus positions.

13. A system for facilitating a machine vision process using a camera having a variable-focus lens having a lens field of view, the system comprising:
a processor programmed to perform the steps of:
a. setting the lens at an image-independent focus position;
b. setting an image-independent image formation setting;
c. obtaining an image of the item with the lens at the focus position and with the set image formation setting;
d. attempting to perform the machine vision process on the image;
e. while performing step (d), initiating steps (b) through (d) using a different image formation setting to obtain a next image of the item; and
f. after a subset of images have been obtained using different image formation settings at the focus position, while performing step (d), initiating steps (a) through (e) using a next focus position to obtain a next image of the item where the next focus position is different than any previous focus position.

14. The system of claim 13 wherein the processor is further programmed to repeat step (f) for a plurality of lens focus positions.

15. The system of claim 11 wherein the machine vision process is one of a symbol reading process and a symbol locating process.

Assignees

• Cognex Corp

Inventors

• Nadabar Sateesh
• Equitz William

Classifications

• G06K7/10544 Primary

  by scanning of the records by radiation in the optical part of the electromagnetic spectrum · CPC title

• G06K7/10722 Primary

  Photodetector array or CCD scanning · CPC title

• H04N23/67

  Focus control based on electronic image sensor signals · CPC title

• H04N23/743

  Bracketing, i.e. taking a series of images with varying exposure conditions · CPC title

• G06K2207/1013

  Multi-focal · CPC title