# US 10,481,429 B2 · Liquid-crystal varifocal lens and focal length control method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,481,429 B2 - Document ID: US10481429B2 - Status: Granted - Kind: B2 - Application number: 15/711,445 - Filed: 2017-09-21 - Published: 2018-06-07 - Granted: 2019-11-19 - Earliest claimed: 2016-12-06 - Assignees: The Doshisha - Applicants: The Doshisha - Inventors: Daisuke Koyama; Yuki Shimizu - Web page: https://patentgrep.com/patent/US10481429B2 ## CPC - G02F 1/133526: {Lenses, e.g. microlenses or Fresnel lenses} - B06B 1/06: operating with piezoelectric effect or with electrostriction (piezoelectric or electrostrictive devices per se H10N30/00) - B06B 1/0644: {using a single piezoelectric element (B06B1/0688 takes precedence)} - G02F 1/294: {Variable focal length devices} - G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS - B06B: METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, {e.g.} FOR PERFORMING MECHANICAL WORK IN GENERAL (for particular applications, see the relevant subclasses, e.g. B07B1/40, B23Q17/12, B24B31/06; measurement of mechanical vibrations G01H; in direction finding, locating, distance or velocity measuring G01S; {generating seismic energy G01V1/02}; control of mechanical vibrations in general G05D; sound-producing devices, e.g. bells, sirens, whistles G10K, {e.g. methods or devices for transmitting, conducting, or directing sound in general G10K11/00}; generation of electrical oscillations H03B; electromechanical resonators in general H03H; electromechanical transducers {for communication techniques, e.g. microphones, speakers} H04R) ## Abstract A liquid-crystal varifocal lens includes a liquid crystal lens, and an ultrasonic transducer for generating an ultrasonic wave with a frequency that matches a resonant frequency of the liquid crystal lens. The ultrasonic transducer generates flexural oscillation in the liquid crystal lens such that the flexural oscillation has a vibration intensity decreasing continuously from the center to the circumference of a liquid crystal layer, whereby the thickness of the liquid crystal layer is changed, with the result that the orientation of the liquid crystal molecules is changed. ## Claims ### Claim 1 A liquid-crystal varifocal lens comprising: a liquid crystal lens including a liquid crystal layer composed of liquid crystal molecules as well as a first substrate and a second substrate disposed with the liquid crystal layer positioned therebetween; and an ultrasonic transducer disposed on either the first substrate or the second substrate, or both, wherein, the ultrasonic transducer generates an ultrasonic wave with a frequency that matches a resonant frequency of the liquid crystal lens, in accordance with an input voltage, whereby, flexural oscillation is generated in the liquid crystal lens such that the flexural oscillation has a vibration intensity decreasing continuously from a center to a circumference of the liquid crystal layer, and a thickness of the liquid crystal layer is changed, thereby changing an orientation of the liquid crystal molecules. ### Claim 2 (depends on 1) The liquid-crystal varifocal lens according to claim 1, wherein the ultrasonic transducer is disposed on the first substrate so as to be apart from the liquid crystal layer and the second substrate. ### Claim 3 (depends on 2) The liquid-crystal varifocal lens according to claim 2, wherein, the first substrate is formed in a disk shape, the liquid crystal layer and the second substrate are formed in disk shapes each having a smaller diameter than the first substrate and being disposed at a center of the first substrate, and the ultrasonic transducer is formed in an annular shape with an inner diameter larger than a diameter of each of the liquid crystal layer and the second substrate but smaller than a diameter of the first substrate, the ultrasonic transducer being disposed on the first substrate with an opening accommodating the liquid crystal layer and the second substrate. ### Claim 4 (depends on 1) The liquid-crystal varifocal lens according to claim 1, wherein the ultrasonic transducer is disposed on each of the first substrate and the second substrate so as to sandwich the liquid crystal lens. ### Claim 5 (depends on 4) The liquid-crystal varifocal lens according to claim 4, wherein, the liquid crystal lens is formed in a disk shape, and the ultrasonic transducer is formed in an annular shape with an opening positioned at a center of the liquid crystal lens. ### Claim 6 (depends on 1) The liquid-crystal varifocal lens according to claim 1, wherein each of the first substrate and the second substrate is a film material. ### Claim 7 (depends on 1) The liquid-crystal varifocal lens according to claim 1, wherein the ultrasonic transducer has electrode patterns formed in circumferential divisions. ### Claim 8 (depends on 1) The liquid-crystal varifocal lens according to claim 1, wherein the flexural oscillation generated in the liquid crystal lens by the ultrasonic transducer is first-order-mode flexural oscillation. ### Claim 9 (depends on 1) The liquid-crystal varifocal lens according to claim 1, wherein the liquid crystal layer is a nematic liquid crystal layer. ### Claim 10 A focal length control method for controlling a focal length of a liquid crystal lens with a liquid crystal layer provided between a first substrate and a second substrate, the method comprising applying an input voltage to an ultrasonic transducer disposed on the liquid crystal lens to generate an ultrasonic wave with a frequency that matches a resonant frequency of the liquid crystal lens, whereby, flexural oscillation is generated in the liquid crystal lens such that the flexural oscillation has a vibration intensity decreasing continuously from a center to a circumference of the liquid crystal layer, and a thickness of the liquid crystal layer is changed, thereby changing an orientation of the liquid crystal molecules. ### Claim 11 (depends on 10) The focal length control method according to claim 10, wherein an amplitude value of the input voltage is changed while keeping the frequency of the input voltage constant. ### Claim 12 (depends on 11) The focal length control method according to claim 11, wherein the frequency of the input voltage is fixed to such a value that the flexural oscillation generated in the liquid crystal lens is first-order-mode flexural oscillation. ### Claim 13 (depends on 11) The focal length control method according to claim 11, wherein, the ultrasonic transducer has electrode patterns formed in circumferential divisions, whereby, the input voltage applied to some of the divisions has an amplitude value different from an amplitude value of the input voltage applied to some other of the divisions, thereby laterally shifting a focal position of the liquid crystal lens.