# US 9,004,698 B2 · Optical micro-projection system and projection method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,004,698 B2 - Document ID: US9004698B2 - Status: Granted - Kind: B2 - Application number: 13/358,269 - Filed: 2012-01-25 - Published: 2012-05-17 - Granted: 2015-04-14 - Earliest claimed: 2009-07-31 - Assignees: Lemoptix SA - Applicants: Lucio Kilcher; Faouzi Khechana - Inventors: Lucio Kilcher; Faouzi Khechana - Web page: https://patentgrep.com/patent/US9004698B2 ## CPC - H04N 9/3194: {including sensor feedback} - G01S 7/4814: {of transmitters alone} - G01S 17/26: wherein the transmitted pulses use a frequency-modulated or phase-modulated carrier wave, e.g. for pulse compression of received signals - G01S 17/42: Simultaneous measurement of distance and other co-ordinates (indirect measurement G01S17/46) - G02B 26/0833: {the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD (G02B26/0825 takes precedence; micromechanical devices in general B81B)} - G06F 3/017: {Gesture based interaction, e.g. based on a set of recognized hand gestures (interaction based on gestures traced on a digitiser G06F3/04883)} - G06F 3/0304: {Detection arrangements using opto-electronic means (constructional details of pointing devices not related to the detection arrangement using opto-electronic means G06F3/033; optical digitisers G06F3/042)} - H04N 9/3129: {scanning a light beam on the display screen (scanning a light beam on a screen in displays other than projection devices G09G3/02; scanning systems in general G02B26/10; projectors using laser light sources in general H04N9/3161)} - H04N 9/3155: {for controlling the light source (light source control per se H05B35/00 – H05B47/00; control of an illumination source for displays in general G09G3/3406)} - H04N 9/3185: {Geometric adjustment, e.g. keystone or convergence (optical or mechanical adjustment of convergence H04N9/317; using scanning means H04N3/22; optical or mechanical adjustments of projectors not peculiar to the presence of an electronic spatial light modulator G03B21/14)} - H04N 9/3188: {Scale or resolution adjustment (scaling in general G06T3/40; resolution modifying circuits for displays in general G09G5/391)} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION - G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract An optical micro-projection system comprising the following components: at least one laser light source (200, 400, 402, 600); at least one movable mirror (102, 103, 203) for deviating light from said light source to allow generation of images on a projection surface (104, 301, 303, 306, 603); a self mixing module for measurement of the distance (604) between the projection source and a projection surface, said self mixing module comprising: —at least one photodiode (401, 601) for monitoring the light emission power of the laser light source; —an optical power variation counter for counting optical power variations (605); successive displacements of said mirror allowing the self mixing module providing successive projection distance measurements of a plurality of points of said projection surface. A projection method for optical micro-projection system and a distance measurement method are also provided. ## Claims ### Claim 1 An optical micro-projection system comprising the following components: at least one light source; at least one movable MEMS mirror for deviating light from said light source to allow generation of images on a projection surface; at least one photodiode for receiving light reflected by said projection surface; a distance evaluation circuit for evaluating a distance between the projection source and a projection surface based on light deviated by said MEMS mirror and received by said photodiode, and for detecting a change in the evaluated distance, due to one or more variations on portions of the projection surface which is/are at different distances from the projection source, wherein the optical micro-projection system further comprises, a means to adjust the at least one light source and the at least one movable MEMS mirror, according to the distance evaluated by the distance evaluation circuit, such that an image projected by the optical micro-projection system can be modified to compensate for said variations on a projection surface so that an undistorted image can be projected on the projection surface, and such that a property of the image projected by the optical micro-projection system, other than the intensity of the image, can be modified in response to a direct physical interaction of a user with a part of the projected image. ### Claim 2 (depends on 1) The system of claim 1, said light source being a laser light source. ### Claim 3 (depends on 1) The system of one claim 1, said distance evaluation circuit being arranged for evaluating the brightness of light deviated by said mirror and received by said photodiode in order to evaluate said distance. ### Claim 4 (depends on 1) An optical micro-projection system according to claim 1, in which said circuit comprises a self-mixing module and an optical power variation counter for counting optical power variations. ### Claim 5 (depends on 3) The system of claim 3, wherein the same component is used as said light source and as said photodiode. ### Claim 6 (depends on 1) The system of claim 1, said photodiode being an avalanche photodiode, said distance evaluation circuit being arranged for evaluating the time-of-flight of the light between emission by said light source and detection by said avalanche photodiode. ### Claim 7 (depends on 1) The system of claim 1, said light source emitting a modulated light at a visible wavelength, said mirror deviating said visible light so as to scan a visible image onto said projection surface, said photodiode receiving said visible light reflected by said projection surface. ### Claim 8 (depends on 1) The system of claim 1, comprising: at least one light source emitting a modulated light at a visible wavelength; at least one additional light source emitting infrared light at an infrared wavelength; said mirror deviating said visible light and said infrared light, so as to scan a visible image onto said projection surface, said photodiode receiving said infrared light reflected by said projection surface. ### Claim 9 (depends on 1) The system of claim 1, in which successive displacements of said mirror allow distance measurements of a plurality of points of said projection surface, and compiling the plurality of measured distances allow generating a projection distance map of the generated points. ### Claim 10 (depends on 1) The system of claim 1, in which the laser light source is an image projection light source usable alternatively in an image projection mode and in a measuring mode during which the projection point does not correspond to an image pixel. ### Claim 11 A projection method for optical micro-projection system comprising the steps of: a) providing at least one light source coupled to at least one movable MEMS micro-mirror for deviating light from said light source to allow generation of images on a projection surface; b) receiving light deviated by said MEMS micro-mirror and reflected by said projection surface with at least one photodiode; c) with a distance evaluation circuit, evaluating a distance between the projection source and a projection surface based on the output of said photodiode and for detecting a change in the evaluated distance, due to one or more variations on portions of the projection surface which is/are at different distances from the projection source; d) adjusting the at least one light source and the at least one movable MEMS mirror, according to the distance evaluated by the distance evaluation circuit, such that an image projected by the optical micro-projection system is modified to compensate for said variations on a projection surface so that an undistorted image can be projected on the projection surface, and such that a property of the image projected by the optical micro-projection system, other than the intensity of the image, is modified in response to a direct physical interaction of a user with a part of the projected image. ### Claim 12 (depends on 11) A projection method for optical micro-projection system according to claim 11, in which successive displacements of said mirror allow distance measurements of a plurality of points of said projection surface. ### Claim 13 (depends on 11) A projection method for optical micro-projection system according to claim 11, comprising: a) for a first point in a projection zone, generating a light signal for projection on a projection surface via reflection on said micro-mirror; b) measuring the projection distance of this point from the projection source; c) displacing the micro mirror position to a new position allowing projecting a further point; d) projecting said further point with said laser light source; e) measuring the projection distance of this further point from the projection system; f) repeating steps “c” to “e” until the projection distances for all points have been measured, and; g) compiling the plurality of measured distance for generating a projection distance map of the generated points. ### Claim 14 (depends on 11) A projection method for optical micro-projection system according to claim 11, in which a self-mixing technique is used for distance measurement. ### Claim 15 (depends on 11) A projection method for optical micro-projection system according to claim 11, in which time-of-flight distance measurement technique is used for distance measurement. ### Claim 16 (depends on 1) The system of claim 1, wherein the modified property comprises scrolling the projected image, resizing the projected image, or moving an object in the projected image. ### Claim 17 An optical micro-projection system comprising the following components: at least one light source; at least one movable MEMS mirror for deviating light from said light source to allow generation of images on a projection surface; at least one photodiode for receiving light reflected by said projection surface; a distance evaluation circuit for evaluating a distance between the projection source and a projection surface based on light deviated by said MEMS mirror and received by said photodiode, and for detecting a change in the evaluated distance, due to one or more variations on portions of the projection surface which is/are at different distances from the projection source, wherein the optical micro-projection system further comprises, a means to adjust the at least one light source and/or the at least one movable MEMS mirror, according to the distance evaluated by the distance evaluation circuit, such that an image projected by the optical micro-projection system can be modified to compensate for said variations on a projection surface so that an undistorted image can be projected on the projection surface, and such that a property of the image projected by the optical micro-projection system, other than the intensity of the image, can be modified in response to a direct physical interaction of a user with a part of the projected image, wherein said circuit comprises a self-mixing module and an optical power variation counter for counting optical power variations in light reflected from the projection surface, and wherein the self-mixing module is configured to adjust the light source to compensate for optical power variations.