# US 2014/0152885 A1 · Method And Apparatus For Calibrating A Camera Lens Flange To Sensor Distance > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0152885 A1 - Document ID: US20140152885A1 - Status: Published application - Kind: A1 - Application number: 13/691,942 - Filed: 2012-12-03 - Published: 2014-06-05 - Earliest claimed: 2012-12-03 - Assignees: Cognex Corporation - Inventors: Laurens Nunnink; Michael Haardt; Rene Delasauce - Web page: https://patentgrep.com/patent/US20140152885A1 ## CPC - H04N 23/55: Optical parts specially adapted for electronic image sensors; Mounting thereof - G02B 1/06: made of fluids in transparent cells - G02B 13/0075: {having an element with variable optical properties} - G02B 26/004: {based on a displacement or a deformation of a fluid} - H04N 23/663: for controlling interchangeable camera parts based on electronic image sensor signals - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS ## Abstract A method and camera assembly for use in a machine vision system, the assembly comprising a support structure forming a mounting flange that is configured for coupling with any of a plurality of exchangeable electrically controllable adjustable focal length lens assemblies, a two dimensional image sensor supported by the support structure and forming a sensor plane spaced from the mounting flange by a flange focal distance and a processor programmed with a flange focal distance error and to use the flange focal distance error to generate lens control signals to compensate for the flange focal distance error when a lens is mounted to the mounting flange. ## Claims ### Claim 1 A camera assembly for use in a machine vision system, the assembly comprising: a support structure forming a mounting flange that is configured for coupling with any of a plurality of exchangeable electrically controllable adjustable focal length lens assemblies; a two dimensional image sensor supported by the support structure and forming a two dimensional sensor plane spaced from the mounting flange by a flange focal distance; and a memory supported by the support structure and storing a flange focal distance error prior to normal operation of the assembly wherein the flange focal distance error is the difference between an ideal flange focal distance and the flange focal distance. ### Claim 2 (depends on 1) The camera assembly of claim 1 further including a processor programmed to use the flange focal distance error to generate lens control signals to compensate for the flange focal distance error when a lens is mounted to the mounting flange. ### Claim 3 (depends on 2) The camera assembly of claim 2 wherein the processor is supported by the support structure that forms the mounting flange. ### Claim 4 (depends on 2) The camera assembly of claim 2 further including an adjustable focal length lens assembly wherein the processor is supported by the lens assembly and obtains the focal distance error from the memory after the lens assembly is connected to the mounting flange. ### Claim 5 (depends on 1) The assembly of claim 1 wherein the flange focal distance error is determined using a first lens assembly during the commissioning procedure and is thereafter used during normal operation with at least a second lens assembly. ### Claim 6 (depends on 3) The assembly of claim 3 further including electrical contacts adjacent the mounting flange and linked to the processor, the contacts for linking to contacts on a lens assembly when the lens assembly is mounted to the mounting flange to provide the lens control signals to the lens assembly. ### Claim 7 (depends on 6) The assembly of claim 6 wherein the processor is further programmed to, when a lens assembly is mounted to the mounting flange, obtain lens characteristics from the lens assembly and use the lens characteristics to generate the lens control signals to compensate for the flange focal distance error. ### Claim 8 (depends on 7) The assembly of claim 7 wherein the lens includes a fixed glass imager lens and a liquid lens. ### Claim 9 (depends on 8) The assembly of claim 8 wherein the lens characteristics include an effective focal length of the imager lens. ### Claim 10 (depends on 2) The assembly of claim 2 further including a distance determiner for determining a target distance from the camera to a target to be imaged, the processor further programmed to use the target distance to generate the lens control signals to compensate for the flange focal distance error. ### Claim 11 (depends on 2) The assembly of claim 2 wherein the lens assembly is a motorized lens assembly and the control signals cause the lens assembly to adjust by an amount equal to the flange focal distance error. ### Claim 12 (depends on 1) The assembly of claim 1 wherein the flange focal distance error is coded into software run by the processor to generate the lens control signals. ### Claim 13 A camera assembly for use in a machine vision system, the assembly comprising: a support structure forming a mounting flange that is configured for coupling with any of a plurality of exchangeable electrically controllable adjustable focal length lens assemblies; a two dimensional image sensor supported by the support structure and forming a two dimensional sensor plane spaced from the mounting flange by a flange focal distance; a memory supported by the support structure and storing a flange focal distance error prior to normal operation of the assembly and for use thereafter with multiple adjustable focal length lens assemblies wherein the flange focal distance error is the difference between an ideal flange focal distance and the flange focal distance; and a processor programmed to obtain the flange focal distance error from the memory and use the flange focal distance error to generate lens control signals to compensate for the flange focal distance error when a lens is mounted to the mounting flange. ### Claim 14 (depends on 13) The assembly of claim 13 wherein the processor is supported by the support structure that forms the mounting flange. ### Claim 15 (depends on 13) The assembly of claim 13 wherein the processor is supported by one of the adjustable focal length lens assemblies. ### Claim 16 (depends on 14) The assembly of claim 14 wherein the processor is further programmed to obtain at least one lens characteristic from a lens memory when a lens is mounted to the support structure and use the flange focal distance error and the at least one lens characteristic to generate the lens control signals to compensate for the flange focal distance error. ### Claim 17 (depends on 13) The assembly of claim 13 further including a distance determiner for determining a target distance from the camera to a target to be imaged, the processor further programmed to use the target distance to generate the lens control signals to compensate for the flange focal distance error. ### Claim 18 A method for use with a camera assembly for use in a machine vision system where the camera assembly includes a support structure forming a mounting flange that is configured for coupling with any of a plurality of exchangeable electrically controllable adjustable focal length lens assemblies, a two dimensional image sensor supported by the support structure and forming a two dimensional sensor plane spaced from the mounting flange by a flange focal distance and a processor, the method comprising the steps of: during a commissioning procedure prior to normal operation of the camera, measuring a flange focal distance error which is the difference between an ideal flange focal distance and the flange focal distance; and programming the processor to use the flange focal distance error to generate lens control signals to compensate for the flange focal distance error when a lens is mounted to the mounting flange for use with the assembly during normal operation of the assembly. ### Claim 19 (depends on 18) The method of claim 18 wherein the camera assembly further includes a memory supported by the support structure, the step of programming including storing the flange focal distance error in the memory where the processor is programmed to retrieve the flange focal distance error from the memory. ### Claim 20 (depends on 19) The method of claim 19 wherein the flange focal distance error is determined using a first lens assembly during a commissioning procedure and is thereafter used during normal operation with at least a second lens assembly. ### Claim 21 (depends on 18) The method of claim 18 wherein the processor is further programmed to, when a lens assembly is mounted to the mounting flange, obtain lens characteristics from the lens assembly and use the lens characteristics to generate the lens control signals to compensate for the flange focal distance error. ### Claim 22 (depends on 21) The method of claim 21 wherein the lens characteristics include an effective focal length associated with the lens assembly. ### Claim 23 (depends on 18) The method of claim 18 wherein the lens assembly mounted to the flange is a motorized lens assembly and the control signals cause the lens assembly to adjust by an amount equal to the flange focal distance error. ### Claim 24 (depends on 18) The method of claim 18 wherein the flange focal distance error is coded into software run by the processor to generate the lens control signals. ### Claim 25 (depends on 18) The method of claim 18 wherein the camera assembly includes a memory supported by the support structure, the method further comprising the steps of: storing the flange focal distance error in the memory; and programming the processor to retrieve the flange focal distance error from the memory. ### Claim 26 (depends on 25) The method of claim 25 wherein the processor is further programmed to obtain at least one lens characteristic from a lens memory when a lens is mounted to the support structure and use the flange focal distance error and the at least one lens characteristic to generate the lens control signals to compensate for the flange focal distance error. ### Claim 27 (depends on 25) The method of claim 25 further including a distance determiner for determining a target distance from the camera to a target to be imaged, the processor further programmed to use the target distance to generate the lens control signals to compensate for the flange focal distance error.