Image Sensor Phase Difference Pixels for OIS Focus Accuracy
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Solution Overview
Problem
The integration of phase difference detection AF systems with optical image stabilization (OIS) in image acquisition devices leads to unstable optical signals, causing inaccuracies in focus control due to differences in phase difference values detected when OIS is driven.
Innovation Solution
An image acquisition device with a grid-patterned image sensor unit featuring phase difference detection pixels, including first and second pixel groups with shielded areas in vertical and horizontal directions, respectively, and an optical image stabilization unit that controls the optical unit's movement based on stabilization results, allowing for selective image processing of electrical signals to maintain focus accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase difference detection pixels are arranged in a conventional uniform pattern, then the AF system can detect focus deviation, but the optical signal becomes unstable when OIS is driven, causing phase difference detection errors
Solution Approach 1:
The image sensor is divided into distinct regions: image detection pixels arranged in a grid pattern and phase difference detection pixels arranged in a non-uniform pattern. This segmentation allows different pixel groups to serve different functions, with the non-uniformly arranged phase difference detection pixels being less affected by OIS-induced optical signal instability, thereby resolving the contradiction between focus detection capability and detection stability.
Solution Approach 2:
Different regions of the image sensor are assigned different functional characteristics. The phase difference detection pixels are specifically arranged in a non-uniform pattern to optimize their performance under OIS conditions, while image detection pixels maintain a regular grid pattern. This local differentiation allows the system to maintain both AF functionality and stability during OIS operation.
2Ease of operation
If OIS is driven for image stabilization, then hand tremor can be corrected, but the optical signal input to the image sensor becomes unstable, causing phase difference values to differ from those detected when OIS is not driven
Solution Approach 1:
The patent employs a dynamic approach where the phase difference detection pixels are arranged in a non-uniform pattern that adapts to the dynamic conditions created by OIS operation. This non-uniform arrangement is specifically designed to maintain detection accuracy despite the dynamic optical signal variations introduced by OIS-driven lens movement for hand tremor correction.
3Productivity
If a grid pattern is used for pixel arrangement, then image detection is optimized, but phase difference detection accuracy deteriorates when OIS is active
Solution Approach 1:
The pixel array is segmented into two distinct functional groups: image detection pixels arranged in a grid pattern for optimized image capture, and phase difference detection pixels arranged in a non-uniform pattern for accurate focus detection under OIS conditions. This segmentation resolves the contradiction by allowing each pixel group to be optimized for its specific function without compromising the other.
Solution Approach 2:
Different local regions of the sensor have different arrangement characteristics tailored to their specific functions. The image detection region uses a regular grid pattern for high productivity, while the phase difference detection region uses a non-uniform pattern that maintains accuracy during OIS operation, thus resolving the local quality conflict between the two detection modes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves focus accuracy by outputting selected phase difference detection pixel values aligned with OIS stabilization, reducing phase difference detection errors even when OIS is active, thus ensuring precise focus control.
Implementation Method 1
an image sensor unit for converting optical information output from the optical unit into an electrical signal
Data Source
AI summary
An image acquiring device, according to one embodiment, comprises: an optical image stabilization unit which compensates for hand trembling; and optical unit which is controlled in accordance with the result value compensated in the optical image stabilization unit; an image sensor unit which converts optical information output from the optical unit into an electric signal; and image information processing unit which image processes the electric signal in accordance with the compensated result value; and an image information output unit which displays the image-processed result, wherein the image sensor unit comprises a plurality of phase difference detection pixels, and a plurality of image detection pixels disposed in a grid pattern along with the plurality of phase difference detection pixels, and the plurality of phase difference detection pixels comprise a first pixel group having a certain area shielded, the certain area being among an area separated by being partitioned in the vertical direction, and a second pixel group having a certain area shielded, the certain area being among an area separated by being partitioned in the horizontal direction, and thus the accuracy of focus may be increased by using a phase difference detection auto focus (AF) method even when an optical image stabilizer (OIS) is being driven.