A Compact Optical Image Stabilization Chip with Actuator Trackability Improvement Controller and Double Offset Cancel Hall Amplifier to Improve Camera Shake Correction.

Image stabilization technique is a very effective way of capturing clear movie and is widely used in cameras, smartphones, wearable cameras, etc. There are two main types of image stabilization techniques: Electronic Image Stabilization (EIS), which uses digital image processing, and Optical Image Stabilization (OIS), which stabilizes the optical axis by physically correcting the position of the image sensor or lens. EIS is low cost because no additional parts are required. But if the image before correction is unclear, correction effect is limited [1]. Therefore, OIS is mainly used. Many of the CMOS image sensor(CIS) installed in recent smartphones easily exceed 10 million pixels. But, the higher the resolution of the CIS, the more serious the image blur caused by camera shake. In addition, the influence of camera shake become even more noticeable during long exposure shooting or zoom shooting. Therefore, further improvements of camera shake correction are required. To realize them, it is necessary to (1) accurately detect the position of the sensor and lens, and accurately calculate the target position for correction, and (2) move the sensor and lens to the target position with high accuracy using an actuator. However, there are the following issues. One is that the detection accuracy decreases due to interference between the detection elements. The other is that the actuator is affected by frictional forces, it is difficult to track the target position, especially when starting to move. In addition, when higher resolution is attempted to improve calculation accuracy, the influence of noise which generated in the analog blocks or caused by mutual interference between analog blocks, and the influence of the variation of AD-conversion error caused by PWM signal using PWM driver become apparent at converting analog signals from detection elements into digital signals, and countermeasures against analog noise are required. Furthermore, from the perspective of commercialization, it is also important to realize a smaller chip to reduce the chip cost. In addition, it is important to achieve more stable and practical performance in the industrial field, but there are few examples of academic analysis of OIS to achieve this. To overcome the above issues and further improve camera shake correction, we propose a compact OIS IC shown in Fig. 1 that applies the following three noble techniques: (1) an Actuator Trackability Improvement Controller (ATIC), (2) a Double Offset Cancel Hall Amplifier (DOC-HA), and (3) a Pulse width modulation Noise Suppression ADC (PNS-ADC).