Lens shifting mechanism with shape memory alloy

Abstract

The invention discloses a lens shifting mechanism with a shape memory alloy (SMA), and the lens shifting mechanism is suitable for an auto-focusing lens module. The SMA wire has two opposite ends and a middle moving segment between the two opposite ends, wherein, the two opposite ends are fixed, and the length direction middle point of the middle moving segment is tightened and suspended at a corresponding hook arranged at the outer edge of a lens retaining part, which causes the middle moving segment to form a stress state relative to the two opposite ends; when the SMA is heated, the middle moving segment can be retracted to pull the corresponding hook at the lens to drive the lens to shift by sliding to achieve auto-focusing effect; an elastic restoring piece can be further arranged at the lens retaining part, and when the SMA contracts to recover the original length due to cooling, the elastic restoring piece can supply restoring force to cause the lens to be restored to the original position; and a correspondingly matched guide rail device can be further arranged between the lens retaining part and an accommodation chamber to cause a lens set to steadily shift in the accommodation chamber by sliding.

Description

technical field [0001] The present invention relates to a lens displacement mechanism, especially a lens displacement mechanism controlled by a shape memory alloy wire (SMA wire) and a spring force for automatic focusing. In an autofocus lens module. Background technique [0002] Currently used digital cameras, mobile phones with shooting functions, notebook computers and other hand-held electronic devices often have a compact camera module (CCM for short) capable of auto-focusing (AF for short). , and the lens module basically includes: a cavity (housing); a lens composed of a lens group (lens group) and a lens holder (lens holder), which is sleeved in the cavity inside and on the optical axis, and can be displaced by sliding or screwing in the direction of approaching the object; and a lens displacement (control) mechanism (lensdisplacement / control mechanism), mainly used to drive the The lens produces a sliding or helical shifting movement on the optical axis to achieve...

AI Technical Summary

Problems solved by technology

[0003] Common designs of existing lens shifting mechanisms include: a piezoelectric motor (piezoelectric motor), which is formed using the principle of piezoelectric (piezoelectric) materials, but generally used piezoelectric materials cannot withstand reflow ( reflow) high temperature, and the special piezoelectric material that can withstand the high temperature of reflow is quite expensive; another kind is called voice coil motor (voice coil motor, referred to as VCM), which uses electromagnetic force and elastic parts (such as springs or shrapnel) ) are formed together, but the voice coil motor will be damaged or the magnetic force will be reduced at the reflow temperature. Therefore, the above-mentioned existing piezoelectric motors and voice coil motors cannot use reflow during assembly, resulting in mass production efficiency. Restricted; another form of shape memory alloy (SMA for short), which uses an SMA device (SMA device), and drives the lens to move through the "heat shrink and cold expand" characteristics of SMA Bit effect, because SMA can reach 5% shrinkage, which is far greater than the thermal expansion and contraction of general materials, and SMA can withstand high temperature reflow, so that reflow can be used during assembly, so the assembly output can be increased and there is a specific Practical value

At present, there are many existing technologies using SMA in the design field of lens shifting mechanism, such as: US5,185,621A, US5,279,123A, US5,459,544A, US6,307,678B2, US6,449,434B1, WO2005001540 、US20020136548、US2007058070、US2007047938、JP64000938、JP9127398、JP62067738、JP3196781、JP2006329111、JP2005275270、JP2005195998、JP2005156892、JP2004184775、JP2004129950、JP2004069986、JP2004038058、JP2000056208等,而上述各专利案虽然都是利用SMA作为镜头移位的驱动 However, the disclosed technical means or driving methods are different; however, most of the structures of the above-mentioned prior art are still relatively complex, and the volume is relatively large, which does not meet the miniaturization requirements of the lens module, such as US6,449,434B1 , which is to use an SMA wire to fix its two opposite ends and make the length of the middle movable section between the two opposite ends to be tensioned to the middle point (longitudinal mid-point) to hang in a pivotable movement A groove on the outer edge of the brake (actuator) is used as a driving force application point, and an opposite protruding pin is provided on the outer edge of the brake and snapped into the outer edge of a lens holder (lens holder) The card slot is used as a stress point, which can drive the brake (actuator) to pivot at an angle through the characteristics of the heat shrinkage and cold expansion of the SMA wire, so that the opposite sides on the brake (actuator) The protruding tip also pivots at an angle synchronously, and then through the cooperation between the protruding pin and the groove on the outer edge of the lens clamping part, the lens clamping part is synchronously driven to pivot at an angle, so that the lens clamping part can Through other structures such as an upper, middle and lower three-stage ladder structure, it can enter the upper, middle and lower three different positions to achieve the adjustment function of lens shift and positioning, that is, to achieve the focus function of the lens

It can be seen from the above that although US6,449,434B1 or other prior art also use SMA wires as the driving force source, they can only drive the lens clamp through other interlocking devices such as brakes (actuator) or other similar lever devices. The displacement of the holding part, that is, in the prior art, an additional interlocking device is almost all set between the SMA wire and the lens holder (lens holder), in order to make the shrinking driving force of the SMA pass through the interlocking device. Converted into the driving force of the lens holder (lens holder); therefore, in the application of SMA in the prior art, the structure and movement mode of the lens shift (control) mechanism are too complicated and not simplified enough, which relatively affects the miniaturization of the lens module Design requirements for cost reduction are not conducive to mass production, so there is still room for further improvement

Images