CML Technology
Core SMA platform designs
Product design with SMA
CML has developed a number of fundamental designs with associated control algorithms. These are described below and form the basis of our current product range. CML is committed to the continuous development of new and improved core designs for an ever-increasing range of product types and to meet more challenging performance metrics.
All CML’s fundamental designs enjoy extensive IP protection, and products may comprise a combination of the fundamental technologies described below. The benefits of SMA are summarised at the bottom of the page.
4-wire
The 4-wire technology from CML consists of 4 SMA wires in a flat and square configuration. By controlling the length of each of the wires, a precise motion control can be achieved. For example, by controlling 2 of the wires, independent motion in both the X and Y directions can be controlled. When all 4 wires are working together, roll motion (Rz) can be achieved. CML’s 4-wire technology is very mature and has shipped in 10s of millions of products worldwide.
This technology is currently being applied to CML’s SMA Lens shift OIS and SMA Sensor shift OIS products.
8-wire
The 8-wire design comprises 2 wires on each side of a square configuration, in a shallow ‘X’ shape, to make up 8 SMA wires in total. The wires are laid out in a cross-pattern at a relatively shallow angle to the Z-axis, typically from 13 to 15 degrees. This unique arrangement means each wire system pulls in a specific direction, so together they combine to control all 6 degrees of freedom, including XYZ translation and tilt. The wire arrangement can also offer a gearing advantage, allowing fast transitions. Specific advantages of the design include a very economical use of components and manufacturing steps - there are no bearings and only a static and moving component.
This technology is currently being applied to CML’s SMA Lens shift AF+OIS and SMA Module Tilt OIS products.
Zero Hold Power
CML’s Zero Hold Power (ZHP) technology enables designs where power is only applied when a positional change is required. When the power is removed from the SMA wires, other components in the system provide a holding force to ensure that the position of the actuator is maintained. For applications where intermittent position adjustment is required the ZHP technology dramatically reduces the average power consumption.
This technology is currently being applied to CML’s SMA Variable Aperture product and can be applied to SMA Autofocus amongst others.
Helical
The helical technology is the ultimate in low height design. Two horizontal SMA wires provide the driving force and control. Ball bearings are distributed in a plane around the moving element, for example a lens, in contact to vertically distributed bearings in other approaches, allowing for low dynamic tilt. The opposing SMA wire configuration allows for fast step transitions of the optical component along a helical path, in a direction perpendicular to the bearing plane. Specifically designed for autofocus, the technology exploits the cylindrical symmetry of the lens to achieve the highest level of performance in an ultra-slim form factor and without impacting image quality.
This technology applies to CML’s current ultra-slim SMA AF actuator designs.
Angled V
This actuator design uses an SMA wire hooked around the moving portion of the actuator at one corner to form an angled ‘V’ and provide motion in an out-of-plane direction, e.g. to move a lens along its optical axis to provide auto-focus functionality in a camera. The design operates the SMA wire against a constant spring force, with the direction of motion defined by appropriate mechanical constraints. Critically, the design maximizes the SMA wire length by running it diagonally across the sides and providing stroke amplification and simple electrical connections to the static portion, ensuring that the range of motion of the lens meets industry requirements for infinity and macro focus.
This technology was used in CML’s early SMA AF actuator products.
Small, lightweight, precise and powerful
CML's SMA actuators are particularly suited to technology applications that require high levels of precision and force, in a compact and lightweight design.
Learn about SMA actuators