Hand-shake correction method and apparatus of camera module for use in mobile device

Abstract

A hand-shake correction apparatus and method for a camera module for typical use in a mobile device. A camera unit includes an angular velocity sensor for sensing an angular velocity of a hand-shake motion of a camera, a position detection sensor for detecting a current position of an image sensor, and an actuator for actuating the image sensor. An Optical Image Stabilizer (OIS) circuit unit controls the actuator using a multi-rate Proportional Integrate Derivative (PID) control scheme that performs control a plurality of times using a shorter control period compared with existing PID controls for a basic period, in which a reference value is updated according to a control reference value by which the image sensor optimally shifts to correct a hand-shake motion.

Description

technical field [0001] The present invention generally relates to camera modules for use in mobile devices. More particularly, the present invention relates to a hand-shake correction method and apparatus for correcting image shake caused by shaking / shaking of the hand that occurs when holding the camera module during photographing. Background technique [0002] Conventional cameras can provide shake-free high-resolution pictures at shutter speeds of 1 / 125 second or less, even if the user's hand shakes slightly during image capture. However, cameras located on mobile devices have less light quantity than conventional cameras during image capture because their lens aperture is smaller than that of conventional cameras, leaving the camera aperture much less opportunity to receive ambient light. As a result, cameras located on mobile devices use slower shutter speeds to compensate for the lack of light, and when cameras in mobile devices take still images, image shake can occu...

AI Technical Summary

Problems solved by technology

[0011] First, when implementing the function of measuring hand shake from the signal measured by the gyro sensor, errors between real and processed signal values ​​accumulate due to offset, drift and phase delay

[0012] Second, it is difficult to expect the best control performance of a VCM actuator using a commonly used controller because it has nonlinear characteristics, time-varying characteristics in which dynamic characteristics change with the lapse of time, and hysteresis characteristics

Furthermore, it is to be considered that even if the proposed controller performs well, its execution is not easy if there are excessive calculations, using devices such as 8-bit processors, which are usually used to control miniaturized devices

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