Imaging Device Focus Pixel Signal Separation and Storage
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Solution Overview
Problem
In imaging devices, high frame rates and increased focus detecting pixel density make it difficult to secure sufficient time to read focus detection signals during the vertical blanking period, affecting focus detection accuracy and requiring innovative signal processing techniques.
Innovation Solution
The imaging device employs a solid-state imaging device with focus detecting pixels arranged in a 2D matrix, utilizing a separating unit to distinguish and process focus detection signals from imaging signals, and includes horizontal and vertical direction focus detection processing units to convert and store these signals in a format suitable for phase difference calculation, enabling efficient storage and access in a DRAM.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frame rate of the solid-state imaging device is increased, then imaging productivity is improved, but the time available to read focus detection signals during the vertical blanking period is reduced
Solution Approach 1:
The pixel array is segmented into imaging pixels and focus detecting pixels with different readout paths. Focus detection signals are separated and read out through a dedicated pathway that can operate independently from the main imaging signal readout, allowing simultaneous processing without time conflicts during the vertical blanking period.
Solution Approach 2:
Focus detection signals are accumulated in a buffer memory during the imaging exposure period, preparing them in advance for rapid readout during the vertical blanking period. This preliminary accumulation allows the system to handle high frame rates while maintaining sufficient time for focus signal processing.
2Measurement precision
If the density of focus detecting pixels is increased, then focus detection precision is improved, but the time required to read all focus detection signals is extended
Solution Approach 1:
The focus detecting pixels are arranged in multiple columns with corresponding relationships between columns. This segmentation allows the readout circuit to process signals from multiple columns simultaneously or in parallel stages, reducing the total readout time while maintaining high pixel density for accurate focus detection.
Solution Approach 2:
The system reads out focus detection signals from multiple columns in parallel, performing more readout operations simultaneously than traditionally required. This excessive parallel processing capability ensures that even with increased pixel density, the total readout time remains within the vertical blanking period.
3Adaptability or versatility
If focus detecting pixels are arranged in multiple positions in the imaging region, then focus detection versatility is improved, but the complexity of storing and accessing all focus detection signals increases
Solution Approach 1:
The patent introduces a column dimension to the focus detection signal storage structure. Focus detection signals are stored not only by row but also organized by column, creating a two-dimensional storage access structure. This allows the phase difference calculation circuit to efficiently access corresponding pixels between different columns without complex addressing logic, reducing overall system complexity while maintaining multi-position focus detection capability.
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 approach allows for accurate focus detection by ensuring focus detection signals are stored and processed in a consistent format, independent of pixel arrangement, enhancing focus detection accuracy and reducing the complexity of DRAM access, thus improving overall imaging performance.
Implementation Method 1
imaging pixels that output pixel signals obtained by performing photoelectric conversion on an optical image of a subject
Data Source
AI summary
An imaging device includes a solid-state imaging device including focus detecting pixels which are arranged together in a region in which imaging pixels are arranged in a form of a two-dimensional (2D) matrix, a separating unit configured to separate imaging signals and focus detection signals from pixel signals output from the solid-state imaging device, to output horizontal direction focus detection signals output from a horizontal direction focus detecting pixel set including two focus detecting signals in a row direction and vertical direction focus detection signals output from a vertical direction focus detecting pixel set including two focus detecting signals in a column direction, a horizontal direction focus detection processing unit configured to convert a format in which the horizontal direction focus detection signals are output to a predetermined format.