In January 2023, Alps Alpine, a leading manufacturer of voice-coil motor (VCM) systems for camera modules, has announced the mass production of a shape-memory alloy (SMA) actuator for CMOS image sensor (CIS) camera modules.
This technology uses SMA wires to provide precise and reliable optical image correction. Unlike traditional actuation systems which rely on bulky and complex mechanisms, SMA actuation offers a compact and energy-efficient solution that can be easily integrated into a wide range of devices, including foldable smartphones where magnetic interference is a concern. The mass production by Alps Alpine can also bring larger sensors and optics and advanced image stabilization to more mid-range handsets.
This article, written by Florian Domengie, Ph.D.., Senior Technology and Market Analyst within the Photonics & Sensing division at Yole Intelligence and Peter Bonanno, Ph.D., Technology & Cost Analyst, Imaging at Yole SystemPlus, both part of Yole Group, explains the market context of this important news and compares the technology to existing solutions. Indeed, this article uses market trends and technology analyses performed by Yole Group’s teams from the Status of the Camera Module Industry 2022 report and the Smartphone Camera Module & CIS Comparison 2022 – Xiaomi report.
SMA actuation stands out among existing actuation solutions.
Actuation systems are used in camera modules primarily to achieve autofocus and OIS, the goal of which is to keep the subject in focus and prevent blurring due to camera shake. This can be achieved by moving optical components or by deforming lenses.
The most common example of moving optical components is autofocus by VCM. While multiple possible configurations exist, they all rely on a combination of springs, coils, and permanent magnets to change the distance between the lens module and the CIS along the optical axis. In its simplest form, electrical current is run through a coil to generate an electromagnetic field that interacts with the field of one or more permanent magnets to create a force. By attaching the lens module to either the coils or the magnets, it can be moved against the springs to bring the subject into focus. The electromagnetic force is proportional to the current through the coil, allowing precise control of the position of the lens module.
Optical image stabilization (OIS) is realized through the same principle but with the components arranged to produce forces perpendicular to the optical axis. Either the lens module or the CIS can be shifted in this manner to compensate for camera shake while capturing a photo or recording video.
Aside from displacing components, the optical system can be adjusted by deforming lenses. The advantages of this approach compared to conventional VCM systems come mainly from the fact that there is no or very little actual motion, so large changes in focus can be driven very quickly and without spending much energy. This also results in a compact, robust system with a long service life, making them particularly adapted to demanding industrial applications like machine vision and barcode reading.
Three approaches to autofocus by lens deformation are considered here. Perhaps the best known is the electrowetting liquid lens technology exemplified by Corning’s Varioptic Lenses, which uses the interface between two immiscible liquids to form a refractive lens surface that can be deformed by controlling the electric potential across the walls of its container. Optotune uses a second approach, wherein a liquid lens is created by encapsulating an optical fluid in a transparent flexible polymer membrane. A ring-shaped element is driven against the membrane by a voice coil motor, causing it to deform. In a third approach, poLight’s TLens uses a piezoelectric film to deform a soft polymer lens.
SMA actuation is similar to that of VCM in that it performs optical correction by moving optical components, either the lens module or the CIS. SMA actuation depends on the defining property of SMA materials: they change crystal phase as a function of temperature. When the SMA is cast into long wires, the expansion/contraction of the crystal lattice produces a significant change in length. Actuation is achieved by incorporating SMA wires into a suspension assembly and carefully controlling the temperature of the wires by running a current through them.
Such systems are lightweight, energy efficient, and powerful, allowing them to move the large, heavy lens modules necessary for large-format CIS. Not relying on permanent magnets means that they don’t need shielding and can be made very compact. The actuator position can be measured by monitoring the wire’s resistance, eliminating the need for position sensors. Cambridge Mechatronics’ 8-wire system, which is used in the Huawei Mate 50 Pro, uses a configuration of 8 independently-controlled SMA wires to achieve actuation along the X, Y, and Z axes as well as pitch and yaw. This combines both autofocus and OIS in a single actuator. The system being mass-produced by Alps Alpine has not yet been observed in the wild, but if it has similar capabilities, it has the potential to increase penetration of advanced optical correction features, especially beyond the premium range of smartphones.
Big news for both the camera module actuation segment and greater camera module market.
CIS camera modules represent a large and expanding industry, with more than 7 billion units shipped in 2022. Looking ahead, the market is set to continue growing beyond the mobile segment, with automotive and consumer products sustaining a new growth cycle. By 2027, the industry revenue is projected to reach $60.2B, with a compound annual growth rate (CAGR) of 9.0%.
Actuators play a critical role in the camera module by enabling features such as autofocus and OIS. These high-tech and adaptable systems can currently be found in most smartphones as well as in some specific applications in consumer products, such as mixed-reality headsets and drones, and in more niche and higher-end industrial applications for machine vision. Actuators are expected to take a larger share of the total camera module business, with the actuator segment accounting for $2.9 billion in 2021 and projected to increase to $6.4 billion by 2027 at a CAGR of 13.8%.
The top six camera module actuation companies, Alps Alpine, Mitsumi, SEMCO, Jahwa, TDK, and LG Innotek, account for over 61% of the market share. However, new challengers, including numerous Chinese companies, are appearing in lens sets and autofocus systems. Nonetheless, high-end OIS remains in the hands of the leading historical players, and innovation is critical for new entrants to differentiate themselves and achieve new design wins. While emerging technologies such as piezo motors, MEMS actuators, and liquid lenses have been brought to market, their use remains somewhat niche, while most products are based on more conventional VCM technology.
Alps Alpine’s announcement is big news for both the actuation segment and the CIS camera module market as a whole. Yole Intelligence’s analysts are of the opinion that the advantages of SMA technology combined with the cost reduction afforded by mass production promises not only to increase penetration of advanced image correction and larger sensors into mid-tier smartphones, but also creates new design possibilities for the higher tier, thus touching all segments of this market.
Despite the very clear potential, this is the first time this promising technology is being produced at this scale. Interestingly, Cambridge Mechatronics has relayed this breaking news from Alps Alpine, leading some to believe it’s their actuator technology that Alps Alpine has licensed.
About the authors
Florian Domengie, Ph.D.. is a Senior Technology and Market Analyst within the Photonics & Sensing division at Yole Intelligence (Yole Group). Florian is engaged in technology and market analyses for various imaging technologies and contributes to the production of relevant reports and projects. Prior to Yole, he worked at STMicroelectronics in process and technology development and R&D project management. Florian has authored or co-authored numerous papers and has five semiconductor R&D and manufacturing patents. He holds an MSc in Engineering Physics, Materials, and Microelectronics from INSA Toulouse (France) and a Ph.D. In Microelectronics and Nanoelectronics from the University of Grenoble-Alpes (France).
Peter Bonanno, Ph.D., is a Technology & Cost Analyst, Imaging at Yole SystemPlus, part of Yole Group. With solid expertise in imaging, optical sensors, and optoelectronics, Peter performs reverse engineering & costing analyses as well as custom projects. He collaborates closely with the laboratory team, and together they create an analysis plan to reveal the device structures, technologies, and manufacturing steps used by leading imaging & photonics companies. At the same time, Peter runs a technology watch to identify the latest innovations and related manufacturing processes. His aim is to gain a comprehensive understanding of the evolution of technologies and identify the strategies of the leading manufacturers. His technology watch is supported by his participation in numerous trade shows and conferences. Peter previously worked at the US Naval Research Laboratory, where he developed tools for time-resolved 2-photon photoluminescence and UV defect imaging. He also authored many scientific papers and articles. Peter holds a Ph.D. in Electrical & Computer Engineering from the Georgia Institute of Technology (Atlanta, Georgia, USA) and a B.S. in Computer Science and Applied Physics (double major) from the New Jersey Institute of Technology (Newark, New Jersey, USA).