Image Sensor Readout Controller Synchronizing Noise and Signal Timing
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Solution Overview
Problem
Existing image sensor technologies suffer from differing readout periods for noise and image signals between pixel rows assigned to focus detection and image forming processing, leading to uneven noise levels and degraded image quality.
Innovation Solution
A controller is used to synchronize the readout of noise and image signals from both focus detection and image forming areas, ensuring equal time intervals between noise and image signal readout, and allowing readout from adjacent rows to reduce noise in the image signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If different pixel rows are used for both focus detection and image forming processing and for image forming processing only, then the readout method can be simplified, but the noise signal readout timing becomes inconsistent between row types, causing noise gaps and image quality deterioration
Solution Approach 1:
The patent applies preliminary action by reading out noise signals from all pixel rows (both first and second types) before reading out image signals. This ensures that noise signals are captured at consistent timing conditions for all rows, eliminating noise gaps while maintaining a simplified readout structure. The noise signal readout is performed in advance at a unified timing, and then image signals are read out subsequently.
2Productivity
If noise signals are read out at different times for different pixel row types, then the readout process can be completed faster, but noise levels become uneven across rows, degrading image quality
Solution Approach 1:
The patent reads out noise signals from all pixel rows before reading out image signals, establishing a consistent temporal reference point for noise measurement across different row types. This preliminary noise readout ensures uniform noise characteristics while maintaining efficient readout throughput.
Solution Approach 2:
The patent achieves homogeneity by ensuring that noise signals from both first-type and second-type pixel rows are read out under identical timing conditions. By standardizing the noise readout timing across all rows, the patent creates uniform noise characteristics throughout the image data, eliminating the noise gaps that would otherwise occur between different row types.
3Manufacturing precision
If the readout timing is synchronized between first and second area pixels, then noise consistency is improved, but the readout control complexity increases
Solution Approach 1:
The patent implements a two-stage readout process where noise signals from all rows are read out first in a preliminary stage, followed by image signal readout in a subsequent stage. This preliminary action approach achieves noise consistency across different pixel row types while using straightforward sequential control logic, avoiding the need for complex synchronized timing mechanisms.
Data Source
AI summary
A sensor includes a pixel portion having first and second areas; and a controller that controls readout of signals from the pixel portion in units of rows. The controller controls to read out a noise signal and an image signal, from each pixel in the first area, controls to read out a noise signal, a focus detection signal, and an image signal, from each pixel in the second area. Further, a time from when the noise signal is read out to when the image signal is read out from each pixel is controlled to be equal between the first area and the second area, and during that time, at least one of the noise signal and the image signal is read out from another row in the first area.