Bi-directional camera autofocus actuator: low power, low profile

January 19, 2016 // By Graham Prophet
ALPS has developed the “ATMC1Z9 Series” bi-direction type autofocus actuator for integration into 13-megapixel smartphone camera modules. The new product achieves low power consumption and a low profile.

ALPS has noted that as of 2015, more than 90% of smartphones in the Chinese market have autofocus functionality; camera performance is seen as a differentiator in a crowded market. Of those, around 70% are fitted with lenses and camera modules supporting eight-megapixel resolution, while roughly 35% (forecast to grow further) support 13 megapixels.

ALPS has responded by developing and starting mass production of the ATMC1Z9 Series Autofocus Actuator for Cameras supporting 13-megapixel resolution and realising low power consumption as well as a low profile. The new product is the first bi-direction type actuator for 13 megapixels. It offers power savings, consuming around one third of the power used by existing preload type actuators, and enables high-speed focusing. With dimensions of 8.5 × 8.5 × 2.8 mm, the actuator has one of the slimmest profiles available, contributing to greater flexibility and quality in casing design.

Bi-direction type actuators set the initial position of the lens at a frequently used focal distance (position) and adjust focus by moving the lens from that point in one direction or the other (bi-directionally) depending on whether the current is positive or negative. This shortens the distance the lens has to travel, thereby reducing the amount of power required to move the lens and enabling high-speed focusing.

To be able to stop and start movement of a suspended lens while still managing to restrict lens tilt requires a high degree of precision in flat spring assembly. ALPS achieves this using mould design, simulation and automated machine design technologies. Lens tilt is less than one tenth of a degree during lens drive. Other applications include camera-integrated office equipment. For a lens barrel size of M6.5 × P0.25mm (ISO metric screw thread), the actuator delivers a stroke (when facing upward) of ≥ +220 µm (@ +90mA), ≤ -30µm (@ -20mA).

ALPS Electric (Tokyo):