Image Sensor Digital Signal Processing for Simultaneous Focus and Imaging
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Solution Overview
Problem
In image-capturing devices, focus detection and image information generation cannot be executed simultaneously when reading out signals from the image sensor, as the signals require analog addition processing before being read out.
Innovation Solution
An image sensor with A/D conversion units, digital adders, and separate output units allows for parallel conversion and output of analog signals to digital signals, enabling simultaneous focus detection and image generation by processing and outputting digital sum signals independently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If analog addition processing is performed within the focus detection pixel before reading out signals, then image information can be generated, but focus detection and image information generation cannot be executed simultaneously
Solution Approach 1:
The patent divides the signal processing into separate functional units: an A/D conversion unit for converting analog signals to digital signals, a digital adder unit for adding digital signals, and separate output units for focus detection signals and image information signals. This segmentation allows parallel processing of different signal types without mutual interference, resolving the contradiction between processing speed and system complexity.
Solution Approach 2:
The patent replaces the traditional analog addition mechanism with a digital addition system. By converting analog signals to digital signals first and then performing addition in the digital domain, the system achieves more flexible and controllable signal processing. This substitution enables independent control of focus detection and image information generation processes, allowing them to be executed simultaneously.
2Adaptability or versatility
If analog signals are converted to digital signals and processed digitally, then simultaneous focus detection and image generation become possible, but additional conversion units and processing circuits are required
Solution Approach 1:
The patent designs the A/D conversion unit and digital adder unit to serve multiple functions: they process both focus detection signals and image information signals through the same conversion and addition pathways. This multi-functionality reduces the need for separate dedicated circuits for each signal type, thereby increasing adaptability while controlling overall system complexity.
Solution Approach 2:
The patent merges the focus detection signal path and the image information signal path into a unified digital processing architecture. Both analog signals from the photoelectric conversion units are converted to digital signals by the same A/D conversion unit and then processed by the digital adder unit, which can selectively output focus detection signals or image information signals based on control signals. This merging approach improves versatility while minimizing the increase in device complexity.
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
Enables high-speed reading of signals for focus detection and image generation, overcoming the limitation of sequential processing in existing technologies.
Implementation Method 1
a pair of photoelectric conversion units 13 and 14 disposed behind the micro-lens 10... generate a pair of focus detection light fluxes... outputs a pair of analog signals
Data Source
AI summary
An image sensor includes: first pixels, each of which receives a pair of light fluxes and outputs a pair of first analog signals; an A/D conversion unit that converts each of pairs of first analog signals to a pair of first digital signals; a digital adder unit that generates digital sum signals each by adding together the pair of first digital signals among pairs of first digital signals; a first output unit that outputs pairs of first digital signals to an external recipient; and a second output unit that outputs the digital sum signals to an external recipient.