Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/006—Resulting in heat recoverable alloys with a memory effect
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22F—CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS
  • C22F1/00—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working
  • C22F1/10—Changing the physical structure of non-ferrous metals or alloys by heat treatment or by hot or cold working of nickel or cobalt or alloys based thereon
• • G—PHYSICS
  • G02—OPTICS
  • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
  • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
  • G02B27/64—Imaging systems using optical elements for stabilisation of the lateral and angular position of the image
  • G02B27/646—Imaging systems using optical elements for stabilisation of the lateral and angular position of the image compensating for small deviations, e.g. due to vibration or shake
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
  • G03B5/00—Adjustment of optical system relative to image or object surface other than for focusing
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
  • G03B2205/00—Adjustment of optical system relative to image or object surface other than for focusing
  • G03B2205/0007—Movement of one or more optical elements for control of motion blur
• • G—PHYSICS
  • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
  • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
  • G03B2205/00—Adjustment of optical system relative to image or object surface other than for focusing
  • G03B2205/0053—Driving means for the movement of one or more optical element
  • G03B2205/0076—Driving means for the movement of one or more optical element using shape memory alloys

Definitions

• the invention relates generally to methods for manufacturing camera lens suspensions such as those incorporated into mobile phones, tablets and other personal devices.
• the invention relates to a method for stabilizing the electrical performance of such camera lens suspensions having shape memory alloy (SMA) wires, such as nitinol wires, used to actuate the suspensions.
• SMA shape memory alloy
• 2013/175197 disclose a camera lens optical image stabilization (OIS) suspension system that has an upper or moving assembly (to which a camera lens element can be mounted) supported by a flexure element or spring plate on a bottom or stationary support assembly.
• the flexure element which is formed from metal such as phosphor bronze, has a moving plate and flexures.
• the flexures extend between the moving plate and the stationary support assembly and function as springs to enable the movement of the moving assembly with respect to the stationary support assembly.
• the moving assembly and support assembly are coupled by nitinol or other shape memory alloy (SMA) wires extending between the assemblies.
• SMA wires has one end attached to the support assembly, and an opposite end attached to the moving assembly.
• the SMA wires are selectively driven by electrical signals to move the moving assembly with respect to the support assembly to actuate the suspension.
• the wires are typically subjected to a stabilization process, also sometimes known as "burn in,” as part of the manufacture of these suspensions.
• a purpose of the stabilization process is to stabilize characteristics such as wire stroke length and resistance asymmetry to provide a stable condition for calibration and to enhance the consistency and accuracy of the suspension's operation.
• the assembled suspensions are electrically connected to a controller, and electrical drive signals are repeatedly applied to the device to cycle the wires through the phase changes.
• This electrical burn in (EB) stabilization process requires relatively complicated equipment and is relatively time consuming to perform.
• Embodiments of the invention include a method and system for stabilizing properties of shape memory alloy (SMA) wires in an optical image stabilization (OIS) suspension of the type having a first or support assembly and a second or moving assembly coupled with respect to one another by the SMA wires.
• the method comprises cyclically mechanically straining and de-straining the wires by moving the moving and support assemblies with respect to one another. Heat can be applied to the wires while mechanically straining and de-straining the wires.
• the temperature, strain, and de-strain levels are configured to cause the wires to cyclically transition between austenite and martensite phases during the mechanical straining and de-straining.
• FIG. 1 is an illustration of a thermo-mechanical stabilization system in accordance with embodiments of the invention, with optical image stabilization (OIS) suspensions on the stabilization system.
• OIS optical image stabilization
• FIG. 2 is detailed illustration of a portion of the system shown in FIG. 1, including an OIS suspension.
• FIG. 3 is an illustration of an alternative releasable mounting structure for use with the system shown in FIG. 1.
• FIG. 4 is an illustration of an alternative releasable mounting structure for use with the system shown in FIG. 1.
• FIG. 5 is a graph of stress v. strain at constant wire temperature (105 deg C) representing a Nitinol wire having 100 repeated cycles or phase transitions from unstressed austenite to stressed martensite showing stabilization of stress plateau and strain offset properties in accordance with embodiments of the invention.
• FIG. 6 is a graph of measured average wire resistance asymmetry v. test conditions for OIS suspensions subjected to thermo-mechanical burn in in accordance with embodiments of the invention and prior art electrical burn in (EB).
• Resistance asymmetry is a ratio characterization of measured wire resistance between the strained and de-strained states.
• FIG. 7 is a graph of measured average actuator stroke v. test conditions for OIS suspensions subjected to thermo-mechanical burn in in accordance with embodiments of the invention and prior art EB.
• FIG. 8 is an illustration of an embodiment of an apparatus in accordance with embodiments of the invention that can thermally and mechanically stabilize SMA wire performance before the wire is installed within an OIS actuator assembly.
• Embodiments of the invention include a thermo-mechanical stabilization or burn in system and process for shape memory alloy (SMA) optical image stabilisation (OIS) suspensions.
• SMA shape memory alloy
• OIS optical image stabilisation
• upper or moving sections or assemblies of the suspensions are reciprocally moved with respect to the bottom or stationary support sections or assemblies to alternately tension and de-tension or recover (i.e., to strain and de-strain or recover) the SMA wires while the wires are heated or otherwise maintained at a predetermined temperature.
• the moving and support assemblies of the suspensions are alternately tensioned and de-tensioned by amounts and at a temperature at which this action and heat causes the SMA wires to cyclically undergo phase transitions between the austenite and martensite phases.
• the temperature and amounts of tension and de-tension can be selected to optimize stabilization results and to minimize possible damage to the wires (e.g., work hardening of the wires).
• Other parameters that can be varied to optimize the stabilization results include the number of strain cycles and the frequency of strain or cycles.
• the stationary support assemblies of a plurality of the suspensions are fixedly mounted to a stationary plate that is heated by a heater.
• the plurality of associated moving assemblies of the suspensions are mounted to an upper moving plate.
• the upper moving plate is reciprocally driven in a back-and-forth manner with respect to the stationary plate to move the moving assemblies with respect to the stationary support assemblies of the suspensions during the stabilization process.
• FIGs. 1 and 2 illustrate a thermo-mechanical stabilization or burn in system 10 and process in accordance with embodiments of the invention and shape memory alloy (SMA) optical image stabilization (OIS) suspensions 12 that can be processed by the system and method.
• an exemplary OIS suspension 12 includes a stationary support or bottom assembly 14, a moving or upper assembly 16, and SMA wires 18. Each of the wires 18 extends between the bottom assembly 14 and the upper assembly 16.
• the illustrated embodiment of OIS suspension 12 has four SMA wires 18 arranged in a rectangular pattern, although other embodiments (not shown) have greater or lesser numbers of such wires.
• System 10 includes a stationary or bottom plate 20, a moving or top plate 22, actuator 24 and heater 26.
• heater 26 is a hot plate that heats the suspensions 12 through the bottom plate 20.
• the heater can be a heated air gun or an oven in which the system 10 is operated.
• Actuator 24 is a voice coil shaker in the illustrated embodiment, and reciprocally moves the top plate 22 (e.g., about path or axis 28).
• a controller (not shown) is coupled to the actuator and optionally the heater.
• the bottom assembly 14 of each suspension 12 is mounted to the bottom plate 20 of the system 10, and the upper assembly 16 of each suspension is mounted to the top plate 22.
• Embodiments of the system 10 include mounting structure (not visible) enabling the bottom assembly 14 of each suspension 12 to be coupled to the bottom plate 20 during the stabilization procedure, and released and removed from the plate following the procedure.
• a mounting structure such as the rod 30 shown FIG. 2 can couple the upper assembly 16 of each suspension 12 to the top plate 22.
• system 10 can include structures such as the pin 40 of FIG. 3 or the key stock 42 of FIG.
• the suspensions 12 are mounted at an angle (e.g., 45°) with respect to the mechanical motion axis 28, enabling pairs of SMA wires 18 sharing a moving crimp to be simultaneously strained or de-strained by the movement of the top plate 22 about the axis 28.
• Other embodiments are configured for OIS suspensions that have fewer or more than four SMA wires, and/or such wires that have other geometrical configurations.
• the stabilization system and method can be configured to operate on fewer than all the wires at the same time.
• suspensions having four nitinol wires were subjected to a stabilization procedure in accordance with embodiments at parameters including a temperature of 105° C and two thousand cycles at 15 Hz.
• Measured parameters of the parts following the stabilization included (1) average part movement at cold temperature of 163.4 ⁇ ⁇ 2.4% strain, and (2) measured part movement at hot temperature of 142.5 ⁇ ⁇ 2.1% strain.
• Other stabilization process test parameters included 125 cycles at 30 Hz (approximately 4 sec.) and 85° C. These test parameters produced part test results having a mean ⁇ 1 standard deviation shown in FIGs. 6 and 7 as single (85 deg C) or replicated (105 deg C) data points.
• Yet other embodiments of the invention include other structures and methods for providing the relative movement between the moving and stationary support assemblies of the suspensions.
• the moving assemblies of the suspensions can be free from engagement by the system while the stationary support assemblies of the suspensions are driven at frequencies and over distances that cause the desired relative movement between the moving and stationary support assemblies.
• the inertia of the moving assemblies when unconstrained by structures other than those of the suspensions themselves, results in the relative movement when the stationary support assemblies are driven.
• Embodiments of the invention provide significant advantages.
• the method stabilizes nitinol wire electrical performance using the heat and repetitive mechanical strain.
• the heated nitinol wires within the OIS suspension are repeatedly mechanically driven during manufacturing to provide a stable position calibrated to the wire's resistance properties.
• the thermo-mechanical stabilization process (1) uses less complex process equipment than prior art approaches through elimination of electrical pinning, (2) facilitates longer burn in for better stabilization, and (3) provides for enhanced product stiffness during test.
• embodiments of the invention can strain wire between austenite and martensite phases at a constant temperature before the wire is installed within an OIS actuator assembly.
• FIG. 6 is a graph of measured asymmetry of suspensions stabilized using embodiments of the invention (test conditions of two thousand cycles at 85° C and 105° C).
• FIG. 7 is a graph of measured stroke of suspensions stabilized using embodiments of the invention (test conditions of two thousand cycles at 85° C and 105° C). For purposes of reference, baseline values and corresponding measured values using two thousand EB cycles are also shown.
• the shape memory wire is subjected to thermo-mechanical burn in stabilization procedures before it is attached to the OIS suspensions.
• lengths of the wire can be unwound from a supply spool and rewound on a different spool after the wire has traveled through a heated zone.
• the straining and de-straining of the wire during the heat zone dwell time can be accomplished by wire travel around single or multiple idler rollers affixed to a moving and controlled linear stage.
• Roller 54 can be moved by surface 56 to increase strain (indicated by arrow 62) and to decrease strain (indicated by arrow 64) in the wire in the heat zone 52.
• the idler roller can be stationary or non-existent for embodiments in which one or both drive rollers have their rotational speed adjusted to induce strain changes in the wire that is suspended in the heat zone.
• the heat zone could represent wire travel through convective, conductive or radiated equipment. After the length and/or resistance properties of wire are stabilized, it can be installed within an OIS actuator having subsequent electrical burn in processes eliminated or minimized with respect to cycle time.

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• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Thermal Sciences (AREA)
• Crystallography & Structural Chemistry (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• General Physics & Mathematics (AREA)
• Optics & Photonics (AREA)
• Adjustment Of Camera Lenses (AREA)
• Studio Devices (AREA)
• Heat Treatment Of Strip Materials And Filament Materials (AREA)

Priority Applications (4)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Citations (7)

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• 2016
  • 2016-09-29 CN CN201680056242.XA patent/CN108026605B/zh active Active
  • 2016-09-29 WO PCT/US2016/054274 patent/WO2017058975A1/en not_active Ceased
  • 2016-09-29 US US15/279,494 patent/US20170088925A1/en not_active Abandoned
  • 2016-09-29 EP EP16852532.7A patent/EP3356566B1/en active Active
  • 2016-09-29 KR KR1020187008577A patent/KR20180059453A/ko not_active Withdrawn
  • 2016-09-29 JP JP2018516557A patent/JP6935395B2/ja active Active

Patent Citations (8)

Non-Patent Citations (1)

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