Image Sensor Phase Detection Grid for Arbitrary Edge Autofocus
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Solution Overview
Problem
Current electronic cameras, especially compact and cost-effective models, face challenges in implementing robust on-chip phase detection for fast and reliable autofocus, as existing solutions often lack comprehensive multi-directional edge detection and phase-shift measurement capabilities.
Innovation Solution
An image sensor with a pixel array comprising intersecting horizontal and vertical phase-detection rows and columns, which generates pairs of line profiles to determine phase shifts associated with arbitrarily oriented edges, enabling robust autofocus and flexible focus adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If dedicated phase-detection sensor is added to image sensor, then phase-detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines phase-detection pixels and imaging pixels into a single integrated pixel array. Phase-detection pixels are interspersed with imaging pixels in the same sensor chip, eliminating the need for separate dedicated phase-detection sensors while maintaining phase-detection capability. This integration reduces device complexity and cost.
Solution Approach 2:
The pixel array serves dual functions: imaging pixels capture scene information while phase-detection pixels measure focus accuracy. By making the sensor universal for both imaging and phase-detection purposes, the patent avoids adding dedicated phase-detection hardware, thereby reducing complexity.
2Device complexity
If only horizontal phase-detection rows are used, then device complexity is reduced, but measurement precision for arbitrary edge orientations deteriorates
Solution Approach 1:
The patent extends phase-detection capability from a single horizontal dimension to two dimensions by adding vertical phase-detection columns that intersect with horizontal rows. This creates a grid pattern that enables measurement of phase shifts for edges oriented in any direction, not just horizontal edges.
Solution Approach 2:
The patent applies different orientations of phase-detection pixels at different locations within the pixel array. Horizontal rows detect phase shifts for horizontally oriented edges, while vertical columns detect phase shifts for vertically oriented edges, creating locally optimized detection capability throughout the array.
3Device complexity
If phase-detection pixels are separated from imaging pixels, then device complexity is reduced, but light collection efficiency deteriorates
Solution Approach 1:
The patent merges phase-detection pixels and imaging pixels into the same physical array structure. Phase-detection pixels are interspersed among imaging pixels rather than being separated, allowing both functions to share the same optical path and light-collection infrastructure, thereby improving light collection efficiency.
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
The solution provides accurate and robust phase-shift measurements for arbitrary edge orientations, enhancing autofocus performance and image quality by intermixing phase-detection and non-phase-detection pixels for improved light collection and artifact correction.
Implementation Method 1
phase-detection autofocus directly measures the degree of misfocus by comparing light passing through one portion of the imaging objective, e.g., the left portion, with light passing through another portion of the imaging objective, e.g., the right portion
Data Source
AI summary
An image sensor for on-chip phase detection includes a pixel array for capturing an image of a scene, wherein the pixel array has a plurality of horizontal phase-detection rows, each including phase-detection pixels for detecting horizontal change in the scene, and a plurality of vertical phase-detection columns, each including phase-detection pixels for detecting vertical change in the scene, and wherein each of the horizontal phase-detection rows intersects each of the vertical phase-detection columns. A phase-detection method includes generating a pair of horizontal line profiles using one of a plurality of phase-detection rows; generating a pair of vertical line profiles using one of a plurality of phase-detection columns intersecting with the one of a plurality of phase-detection rows; and determining phase shift associated with at least one arbitrarily oriented edge in a scene, based upon the pair of horizontal line profiles and the pair of vertical line profiles.