Stereoscopic electro-optical system for automated inspection and/or alignment of imaging devices on a production assembly line

• US 5,638,461 A
• Filed: 04/12/1996
• Issued: 06/10/1997
• Est. Priority Date: 06/09/1994
• Status: Expired due to Fees

• Current Assignee: Kollmorgen Instrument Corporation
• Original Assignee: Kollmorgen Instrument Corporation
• Inventors: Fridge, David A.
• Primary Examiner(s): Boudreau, Leo
• Assistant Examiner(s): Tran, Phuoc
• Application Number:
  US08/631,042
• Time in Patent Office: 424 Days
• Field of Search: 382/141, 382/148, 382/151, 382/154, 382/201, 382/276, 382/285, 382/287, 382/291, 382/293, 382/294, 382/295, 382/302, 348/47, 348/48, 348/92, 348/93, 348/180, 348/189, 348/190, 348/191
• US Class Current: 382/141
• CPC Class Codes: G01N 21/88 Investigating the presence of flaws or contamination
• CPC Class Codes: G06T 2207/10012 Stereo images
• CPC Class Codes: G06T 7/0004 Industrial image inspection
• CPC Class Codes: G06T 7/30 Determination of transform parameters for the alignment of images, i.e. image registration
• CPC Class Codes: G06T 7/85 Stereo camera calibration
• CPC Class Codes: G06T 7/97 Determining parameters from multiple pictures depth or shape recovery from multiple images G06T7/55; stereo camera calibration G06T7/85
• CPC Class Codes: H04N 13/239 using two 2D image sensors having a relative position equal to or related to the interocular distance H04N13/243 takes precedence
• CPC Class Codes: H04N 13/243 using three or more 2D image sensors
• CPC Class Codes: H04N 13/246 Calibration of cameras
• CPC Class Codes: H04N 13/25 using two or more image sensors with different characteristics other than in their location or field of view, e.g. having different resolutions or colour pickup characteristics; using image signals from one sensor to control the characteristics of another sensor
• CPC Class Codes: H04N 2013/0081 Depth or disparity estimation from stereoscopic image signals

Abstract

Disclosed is a stereoscopic optical inspection system. A computer uses the stereoscopic information to compute and correct for angular and distance misalignments between the unit-under-test and the inspection system. A feature of the optical system is the use of multiple high-resolution inspection cameras, in conjunction with a single stereoscopic reference camera. One example of a preferred embodiment is presented as an electro-optical inspection system for inspection and/or alignment of cathode-ray-tube displays and other video displays on a production assembly line.

Claims

1. A three-dimensional optical inspection and alignment system for electronically adjustable visual displays on a production assembly line comprising

a rigid support,

two cameras mounted on said support, said cameras oriented to have an overlapping field of view with each camera being calibrated to define two-dimensional locations in said overlapping field of view,

computer means for identifying calibrated two-dimensional locations of said visual displays in said overlapping field of view from said cameras, determining three-dimensional coordinates of said visual displays in said field of view, and transforming three-dimensional coordinates to two-dimensional coordinates in an ideal viewpoint, and

means for electronically adjusting said visual displays based on said two dimensional coordinates.

2. The inspection system as defined by claim 1 and including a plurality of high resolution cameras and at least one stereo reference camera, said stereo reference camera viewing all of said field of view, and said plurality of high resolution cameras each covering a portion of said field of view and collectively covering all of said field of view.

3. The inspection system as defined by claim 1 and further including a frame grabber means for storing image frames from said plurality of cameras and providing said image frames to said computer means for identifying calibrated two-dimensional locations and determining three-dimensional locations of said objects.

4. The inspection system as defined by claim 3 wherein each image frame has a plurality of pixels each identified by row and column, each pixel being associated with a line in space, a three dimensional location of an object in said field of view being defined by the intersections of lines in space from said image frames.

5. A method of optically inspecting and aligning an electronically adjustable visual display on a production line comprising the steps of:

a) viewing said visual display with two rigidly mounted separated cameras having an overlapping field of view with each camera being calibrated to define two-dimensional locations in said overlapping field of view,

b) determining three-dimensional locations of said visual display in said overlapping field of view from said two-dimensional locations,

c) transforming said three-dimensional locations to a two-dimensional coordinate system, and

d) electronically adjusting said display based on said two-dimensional coordinate system.

6. The method as defined by claim 5 wherein each frame of each camera has a plurality of pixels, each identified by row and column, each pixel being associated with a line in space, said step of determining three-dimensional locations including determining the intersections of lines in space from frames from said plurality of cameras.

7. A three-dimensional optical inspection and alignment system for electronically adjustable visual displays on a production assembly line comprising

a rigid support,

a plurality of cameras mounted on said support, said cameras oriented to have an overlapping field of view with each camera being calibrated to define two-dimensional locations in said overlapping field of view, said plurality of cameras including a plurality of high resolution cameras and at least one stereo reference camera, said stereo reference camera viewing all of said field of view, and said plurality of high resolution cameras each covering a portion of said field of view and collectively covering all of said field of view,

computer means for identifying calibrated two-dimensional locations of said visual displays in said overlapping field of view from said cameras, determining three-dimensional coordinates of said visual displays in said field of view, and transforming three-dimensional coordinates to two-dimensional coordinates in an ideal viewpoint,

a frame grabber means for storing image frames from said plurality of cameras and providing said image frames to said computer means for identifying calibrated two-dimensional locations and determining three-dimensional locations of said objects, and

means for electronically adjusting said visual displays based on said two dimensional coordinates.