Expansion of lens driver lineup suitable for dark places or distant subjects
Development of feedback control drivers and various actuator control technologies.

Compared to electronic image stabilization, optical image stabilization solutions enable clear, shake-free shooting even in dark environments and with distant subjects.

ROHM is expanding its lens driver business for smartphone camera image stabilization. The company has expanded its lineup of lens driver ICs by combining analog signal processing technology and driver circuit technology accumulated from motor drivers and the like with advanced digital signal processing technology.

With existing electronic correction solutions dominating the mainstream market, the strategy is to continue pushing optical image stabilization (OIS) driver solutions capable of in-frame correction.

▲ Comparison of optical image stabilization (left) and electronic image stabilization. As shown in the photo, even dark areas and distant subjects appear clearly.

With smartphone cameras evolving rapidly in recent years, it has become common practice to incorporate features such as autofocus, image stabilization, and zoom. Accordingly, ROHM Co., Ltd., which has been developing lens driver ICs for camera modules since 2008, has been supplying products to smartphone manufacturers. ROHM developed a model that supports a ringing correction function to suppress excessive vibration for feedforward control, which was the mainstream for autofocus lens drivers at the time, and a bidirectional driving actuator called Bi-Direction.

In 2012, the lineup was further expanded by developing lens driver ICs for optical image stabilization that began to be installed in smartphones, models compatible with ball-type actuators with different structures, as well as lens drivers for feedback-controlled autofocus.

Electronic image stabilization basically detects image deviations between frames and corrects them to eliminate such deviations, whereas optical image stabilization is a method that detects and corrects hand shake signals through a gyroscope sensor installed in the camera or smartphone body.

While both electronic and optical image stabilization have their advantages and disadvantages, optical image stabilization has recently become highly valued for its ability to achieve high performance in dark environments or when photographing distant subjects. Accordingly, manufacturers expect that the adoption of optical stabilization will increase in the future, and that there will be a greater number of cameras that utilize both optical and electronic methods to further enhance image stabilization capabilities.

Optical image stabilization requires mechanical components for driving and area for its control IC, but it can utilize the entire effective area of the pixel and enables correction not only between frames but also within frames. In particular, the absence of image quality degradation due to image processing distinguishes it from electronic image stabilization methods.

In addition, there are various methods of optical image stabilization; in digital still cameras, there is the 'lens shift method,' which shifts only the corrected lenses within the lens group, and the 'sensor shift method,' which fixes the lenses and shifts the image sensor. In smartphone cameras, the 'lens barrel shift method,' which shifts the entire lens group, is mainly adopted. ROHM is also promoting the development of control technology for various actuators.

Advisor Yoshihiro Sekimoto stated, “ROHM’s lens driver ICs for camera modules are planned to be primarily supplied to flagship models capable of delivering top performance in the smartphone market, which has now entered a mature stage.”