# US 5,707,128 A · Target projector automated alignment system > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,707,128 A - Document ID: US5707128A - Status: Granted - Kind: A - Application number: 08/670,737 - Filed: 1996-06-24 - Granted: 1998-01-13 - Earliest claimed: 1996-06-24 - Assignees: Hughes Electronics Corporation - Inventors: Jon Dugdale - Web page: https://patentgrep.com/patent/US5707128A ## CPC - G09B 9/326: {the image being transformed by optical means} - G09B: EDUCATIONAL OR DEMONSTRATION APPLIANCES; APPLIANCES FOR TEACHING, OR COMMUNICATING WITH, THE BLIND, DEAF OR MUTE; MODELS; PLANETARIA; GLOBES; MAPS; DIAGRAMS (devices for psychotechnics or for testing reaction times A61B5/16; games, sports, amusements A63; projectors, projector screens G03B) ## Abstract An alignment system and method for maintaining the alignment of a target projector with another image projector in a simulator system. The target projector system includes a slewable fold mirror to move the target image in azimuth and elevation. A two position beam splitter is arranged so that in a projector operating mode, the beam splitter is positioned out of the target projector image light path, and in a projector maintenance mode, the beam splitter is positioned in the image light path. A photo-sensitive array is positioned relative to the beam splitter such that light from the display screen is redirected from the light path onto the array. During the maintenance mode, reference light points are generated on the display screen, and the target projector is precisely aligned by use of processing the images captured by the array to calculate an error signal representing the distance between the light point image and the center of the array. The error signal is used to command servo motors positioning the slewable fold mirror to precisely align the target projector to the light points. The servo commands resulting in the precise alignment for each reference point are stored in a lookup table in memory. These commands are used to obtain additional table values for interpolated points between the reference points. The table values are then used to adjust the servo motor commands positioning the slewable mirror during normal operation of the target projector. ## Claims ### Claim 1 An alignable image projector system for projecting slewable visual images, comprising: a display screen; a first image projector responsive to image data signals for projecting a visual target image along a target image light path; a slewable optical apparatus disposed in the light path between the image projector and the display screen for slewing the position of the projected visual image on the display screen in response to slew commands; apparatus for generating a reference pattern of one or more light points on the display screen, each light point at a corresponding reference position; a position sensor apparatus for sensing the position of a light point in relation to a sensor reference point and generating a sensor signal indicative of said sensed position; an optical relay operable during a system maintenance mode to relay the image from the display screen to the position sensor apparatus; and control apparatus responsive to the sensor signal during the maintenance mode to generate said slew commands to position said slewable optical apparatus so as to align said optical apparatus with said one or more light points of said reference pattern, said control apparatus including memory apparatus for storing slew command data representing alignment command data for controlling said slewable optical apparatus during a projector operating mode. ### Claim 2 (depends on 1) The system of claim 1 wherein the slewable optical apparatus comprises a slewable fold mirror and positioning apparatus for slewing the position of the fold mirror in response to the slew commands. ### Claim 3 (depends on 2) The system of claim 2 wherein the positioning apparatus comprises servo motor apparatus. ### Claim 4 (depends on 1) The system of claim 1 wherein the slewable optical apparatus comprises apparatus for slewing said position of said target image in azimuth and in elevation. ### Claim 5 (depends on 1) The system of claim 1 wherein said optical relay comprises a beam splitter selectively positionable in said target light path during said maintenance mode to relay said display screen image to said position sensing apparatus. ### Claim 6 (depends on 5) The system of claim 5 wherein the optical relay includes relay positioning apparatus responsive to relay position commands for positioning the beam splitter in the target light path at an alignment position during the maintenance mode, and for positioning the beam splitter out of the target light path at a projector operating position during the normal operating mode of the projector. ### Claim 7 (depends on 1) The system of claim 1 further including an image generator for generating said image data signals, said image generator providing image data signals for producing an alignment image during said maintenance mode for coarse alignment of said target projector with a reference light point. ### Claim 8 (depends on 7) The system of claim 7 wherein said alignment image includes a crosshair and a nominal circle. ### Claim 9 (depends on 1) The system of claim 1 wherein said sensor signal is proportional to the distance between a center of said position sensor apparatus and the image of the reference light point relayed to said position sensor apparatus, and wherein said control apparatus includes a feedback loop apparatus operable during the maintenance mode for moving said slewable optical apparatus to reposition the slewable optical apparatus until the reference light point image is centered on said center of said position sensing apparatus. ### Claim 10 (depends on 1) The system of claim 1 wherein said apparatus for generating said reference light pattern comprises a fiber optic array. ### Claim 11 (depends on 1) The system of claim 1 wherein said apparatus for generating said reference light pattern comprises a second image projector for projecting a pattern of light points onto said display screen. ### Claim 12 (depends on 11) The system of claim 11 wherein said first projector is a target projector comprising a visual display simulator system. ### Claim 13 (depends on 12) The system of claim 12 wherein said second projector is an out-of-the-window projector comprising the simulator system. ### Claim 14 (depends on 1) The system of claim 1 wherein said position sensing apparatus comprises a two-dimensional photosensitive array device for capturing a two-dimensional image of a scene within an array device field of view. ### Claim 15 A method for aligning an image projector to a display screen, the image projector including a slewable optical apparatus disposed in the light path between the image projector and the display screen for slewing the position of the projected visual image on the display screen in response to slew commands, the method comprising the following steps: generating a reference pattern of one or more light points on the display screen, each light point at a corresponding reference position; disposing an optical relay in the light path between the image projector and the slewable optical apparatus to relay an image of a reference light point on said display screen onto a position sensor apparatus; generating a sensor signal indicative of the position of one of the reference light points in relation to a sensor reference point; issuing slew commands for slewing the optical apparatus to align the relayed image of the reference light point with each one of the detector reference points; storing slew command data representing the alignment of the relayed image with the detector reference points for subsequent use in a normal system operating mode. ### Claim 16 (depends on 15) The method of claim 15 further comprising a manual setup process comprising the steps of: generating an alignment pattern by the image generator onto the display screen; using the projected alignment pattern to slew the slewable optical apparatus to coarsely align the image projector with each of the reference light points; and for each coarse alignment of the image projector with a reference light point, storing slew command data representing the position of the slewable optical apparatus at each coarse alignment position. ### Claim 17 (depends on 16) The method of claim 16 further comprising the step of using said slew command data representing the position of the slewable optical apparatus at each coarse alignment position to pre-position said slewable optical apparatus prior to said step of issuing slew commands to align said sensor reference point with said relayed image of said reference light point. ### Claim 18 (depends on 15) The method of claim 15 wherein said slew command data is stored in a lookup table in a memory. ### Claim 19 (depends on 15) The method of claim 15 further comprising the step of using said lookup table data to generate an interpolated lookup table including slew command data for positions intermediate said reference light positions.