# US 7,612,948 B2 · Controllable optical lens > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,612,948 B2 - Document ID: US7612948B2 - Status: Granted - Kind: B2 - Application number: 10/599,353 - Filed: 2005-03-29 - Published: 2008-10-02 - Granted: 2009-11-03 - Earliest claimed: 2004-03-30 - Assignees: Koninklijke Philips Electronics N.V. - Inventors: Albert H. J. Immink; Bernardus H. W. Hendriks; Stein Kuiper; Ivon F. Helwegen; Marco A. J. Van As - Web page: https://patentgrep.com/patent/US7612948B2 ## CPC - G02B 3/14: of variable focal length - G02B 26/005: {based on electrowetting} - Y10S 359/90: Methods - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A controllable optical lens system, comprises a chamber housing first and second fluids, the interface between the fluids defining a lens surface. An electrode arrangement controls the shape of the lens surface and has first and second electrodes. A parameter is determined by the system dependent on the electrical resistance through at least one of the lens fluids between the first and second electrodes. Thus, the series resistance through a lens fluid is used as a measure of meniscus position. ## Claims ### Claim 1 A controllable optical lens system, comprising: a chamber housing first (10) and second (12) fluids, the interface between the fluids defining a lens surface; an electrode arrangement for electrically controlling the shape of the lens surface, the electrode arrangement comprising first (14) and second (16) electrodes; means for measuring the electrical resistance (REW) through at least one of the lens fluids (10) between the first and second electrodes; and means for determining the meniscus position of the lens in dependence upon the measured electrical resistance (REW). ### Claim 2 (depends on 1) system as claimed in claim 1, further comprising means for measuring the electrical capacitance (CEW) through at least one of the lens fluids (10) between the first and second electrodes. ### Claim 3 (depends on 1) A system as claimed in claim 1, wherein the means for means for measuring the electrical resistance (REW) through at least one of the lens fluids (10) between the first and second electrodes comprises: an ac power source (40);means (42,44) for analyzing the current supplied by the ac power source. ### Claim 4 (depends on 3) A system as claimed in claim 3, wherein the means for measuring the electrical resistance (REW) through at least one of the lens fluids (10) between the first and second electrodes providing a lens power feedback function further comprises a first series resistor (Rm) in series between the power source and one of the first and second electrodes, and wherein the means (42,44) for analyzing a current supplied by the ac power source analyzes the voltage drop across the first series resistor. ### Claim 5 (depends on 4) A system as claimed in claim 4, wherein the means for analyzing is for determining a time constant for the response of the system. ### Claim 6 (depends on 4) A system as claimed in claim 4, further comprising a second series resistor (Rs) which is selectively switched into circuit with the first resistor (Rm). ### Claim 7 (depends on 6) A system as claimed in claim 6, wherein the means for analysing is for determining first and second time constants for the response of the system with and without the second series resistor. ### Claim 8 (depends on 7) A system as claimed in claim 7, wherein the time constants are obtained by a best fit analysis. ### Claim 9 (depends on 3) A system as claimed in claim 3, wherein the ac power source signal used for determining is superposed onto the dc power source signal used for driving the lens. ### Claim 10 (depends on 1) A system as claimed in claim 1, wherein the electrode arrangement comprises: a drive electrode arrangement comprising a base electrode (14) and a side wall electrode (16). ### Claim 11 (depends on 10) A system as claimed in claim 10, wherein the side wall electrode (16) comprises an annular electrode which surrounds the chamber. ### Claim 12 (depends on 10) A system as claimed in claim 10, wherein the area of overlap of one of the fluids (10) with respect to the side wall electrode (16) varies in dependence on the lens surface position, and the side wall electrode (16) is formed from a material having a higher resistance than said one of the fluids. ### Claim 13 (depends on 12) A system as claimed in claim 12, wherein the side wall electrode (16) is formed from a non-metal. ### Claim 14 (depends on 1) A system as claimed in claim 1, wherein the first liquid (10) comprises a polar or conductive liquid and the second liquid (12) comprises a nonconductive liquid. ### Claim 15 A method of sensing the lens position of a controllable optical lens, the lens comprising a chamber housing first and second liquids (10,12), the interface between the liquids defining a lens surface and an electrode arrangement (14,16) for electrically controlling the shape of the lens surface, the electrode arrangement comprising first and second electrodes (14,16), wherein the method comprises: means for measuring the electrical resistance (REW) through at least one of the lens fluids (10) between the first and second electrodes; and using the measured electrical resistance (REW) to determine the meniscus position of the lens. ### Claim 16 (depends on 15) A method as claimed in claim 15, further comprising determining an electrical capacitance (CEW) between the first and second electrodes. ### Claim 17 (depends on 15) A method as claimed in claim 15, wherein determining a parameter comprises determining a charging time constant for the lens. ### Claim 18 (depends on 17) A method as claimed in claim 17, wherein determining a parameter comprises determining two charging time constants for the lens, one with and without an additional known resistance (Rs), and further determining the lens capacitance (CEW) and resistance (REW) from the two time constant measurements. ### Claim 19 (depends on 17) A method as claimed in claim 17, wherein determining a charging time constant comprises driving the lens with an AC voltage. ### Claim 20 (depends on 17) A method as claimed in claim 17, wherein determining a charging time constant comprises driving the lens with the superposition of a DC voltage and a lower voltage square wave AC voltage. ### Claim 21 (depends on 17) A method as claimed in claim 17, wherein determining a charging time constant comprises driving the lens with the superposition of a DC voltage and a lower voltage sinusoidal wave AC voltage and measuring the phase relation between the voltage and the induced current through the lens. ### Claim 22 (depends on 17) A method as claimed in claim 17, wherein the time constant is obtained by a best fit analysis. ### Claim 23 (depends on 17) A method as claimed in claim 17, wherein the time constant is obtained using a look up table.