System and method for expansion of field of view in a vision system

Patent metadata

Field	Value
Publication number	US-9857575-B2
Application number	US-201514680143-A
Country	US
Kind code	B2
Filing date	Apr 7, 2015
Priority date	Feb 6, 2012
Publication date	Jan 2, 2018
Grant date	Jan 2, 2018

Abstract

This invention provides a field of view expander (FOVE) removably attached to a vision system camera having an image sensor defining an image plane. In an embodiment the FOVE includes first and second mirrors that transmit light from a scene in respective first and second partial fields of view along first and second optical axes. Third and fourth mirrors respectively receive reflected light from the first and second mirrors. The third and fourth mirrors reflect the received light onto the image plane in a first strip and a second strip adjacent to the first strip. The first and second optical axes are approximately parallel and a first focused optical path length between the scene and the image plane and a second focused optical path between the image plane and the scene are approximately equal in length. The optical path can be rotated at a right angle in embodiments.

First claim

What is claimed is:

1. A system for expanding a field of view of a scene imaged by a vision system camera having a lens assembly and an image sensor defining an image plane, the system being constructed and arranged to search and analyze features of interest in the scene comprising:
at least a first mirror and a second mirror that transmit light from a field of view in a scene in at least a first partial field of view along a first optical axis and a second partial field of view along a second optical axis; and
at least a third mirror receiving reflected light from the first mirror and a fourth mirror receiving reflected light from the second mirror, the third mirror and the fourth mirror reflecting the light through the lens assembly onto the image plane in a first strip and a second strip adjacent to the first strip, wherein the first strip and the second strip are arranged in a stacked relationship.

2. The system as set out in claim 1 wherein the first optical axis and the second optical axis are approximately parallel and a first focused optical path length between the scene and the image plane and a second focused optical path between the image plane and the scene are approximately equal in length.

3. The system as set forth in claim 1 wherein the first strip and the second strip are arranged in a vertically stacked relationship on, each having a common horizontal overlap region.

4. The system as set forth in claim 3 wherein the overlap region is at least as large horizontally as a largest feature of interest to be searched by the vision system camera.

5. The system as set forth in claim 4 wherein the searched feature of interest is a symbology code, the system further comprising a symbology code decoding system that receives information related to located symbology codes from the vision system camera and outputs code data to a further interconnected process.

6. The system as set forth in claim 5 wherein the symbology code is located on an object moving on a conveyor through the scene.

7. The system as set forth in claim 1 wherein the first mirror, the second mirror, the third mirror and the fourth mirror are enclosed in a housing and the housing is operatively connected to a coupling removably attached to the vision system camera such that the vision system camera is adapted for use free of the coupling, the coupling including a lens shroud that selectively allows access to the lens assembly of the vision system camera.

8. The system as set forth in claim 1 further comprising a vision processor and wherein the lens assembly comprises a liquid lens assembly, and further comprising an auto-focus process operated by the vision processor constructed and arranged to focus the liquid lens assembly.

9. The system as set forth in claim 1 further comprising a vision processor that determines distance to an object based upon at least one of (a) size of an overlap region between the first partial field of view and the second partial field of view, and (b) relative position of an identified feature in an overlap region or the first partial field of view and the identified feature in an overlap region of the second partial field of view.

10. The system as set forth in claim 1 wherein the first mirror, the second mirror, the third mirror and the fourth mirror are located in a mirror housing having a housing optical path therethrough, and further comprising a vision processor that determines focus of the lens assembly based upon an image of fiducial located along the housing optical path.

11. The system as set forth in claim 10 wherein the fiducial is located on at least one of the first mirror, the second mirror, the third mirror, the fourth mirror, and a transparent window on the mirror housing.

12. The system as set forth in claim 1 wherein a first partial field of view and a second partial field of view are approximately free of overlap therebetween, and further comprising a vision processor that is constructed and arranged to identify a first partial code in the first partial field of view and a second partial code in the second partial field of view, the vision processor being further constructed and arranged to stitch together the first partial code and the second partial code and generate decoded information therefrom.

13. The system as set forth in claim 12 wherein the first partial code is provided in a first captured image frame at a first time, the first captured image frame being stored and the second partial code is provided in a second captured image frame at a second time subsequent to the first time.

14. A system for expanding a field of view of a scene imaged by a vision system camera having a lens assembly and an image sensor defining an image plane, the system being constructed and arranged to search and analyze features of interest in the scene comprising:
at least a first mirror and a second mirror that transmit light from a field of view in a scene in at least a first partial field of view along a first optical axis and a second partial field of view along a second optical axis, wherein the first mirror comprises a first outboard mirror oriented over the first partial field of view and the second mirror comprises a second outboard mirror oriented over the second partial field of view, each of the first outboard mirror and the second outboard mirror being oriented at an acute angle with respect to a horizontal plane;
at least a third mirror receiving reflected light from the first mirror and a fourth mirror receiving reflected light from the second mirror, the third mirror and the fourth mirror reflecting the light through the lens assembly onto the image plane in a first strip and a second strip adjacent to the first strip, wherein the third mirror comprises a first inboard mirror and the fourth mirror comprises a second inboard mirror, each of the first inboard mirror and the second inboard mirror being respectively located on a first vertical plane and a second vertical plane, each substantially perpendicular to the horizontal plane, wherein the first inboard mirror and the second inboard mirror are constructed and arranged to direct light from a scene from a vertical optical path through a right angle onto a horizontal optical path toward the image sensor.

15. The system as set forth in claim 14 wherein the sensor is rotated so that a width dimension is oriented vertically.

16. The system as set forth in claim 14 wherein the first outboard mirror and the second outboard mirror are each oriented at opposing 45-degree angles with respect to the horizontal plane.

17. The system as set forth in claim 16 wherein the first inboard mirror and the inboard mirror are each oriented at opposing 45-degree angles with respect to each of the first vertical plane and the second vertical plane, respectively, that each (a) is perpendicular to the horizontal plane and (b) resides on an optical axis of the vision system camera.

18. The system as set forth in claim 14 wherein the first outboard mirror, the second outboard mirror, the first inboard mirror and the second inboard mirror are mounted in a mirror enclosure having a unitary tubular structure and at least one removable end cover.

19. The system as set forth in claim 18 wherein the mirror enclosure includes keyway slots for engaging mounting structures and accessories.

20. The system as set forth in claim 19 wherein the accessories include illuminators.

21. The system as set forth in claim 19 further comprising an extension tube that extend

Assignees

• Cognex Corp

Inventors

• Nunnink Laurens
• Gerst Carl
• Equitz William
• Engle Matthew D

Classifications

• G02B27/143

  using macroscopically faceted or segmented reflective surfaces · CPC title

• G06K7/10603

  Basic scanning using moving elements · CPC title

• G02B27/1066 Primary

  for enhancing image performance, like resolution, pixel numbers, dual magnifications or dynamic range, by tiling, slicing or overlapping fields of view · CPC title

• G02B26/12

  using multifaceted mirrors · CPC title

• G02B17/06

  using mirrors only {, i.e. having only one curved mirror (used in non-imaging applications G02B19/00)} · CPC title