Microlens Pixel Correction for CMOS Sensor Sensitivity Matching
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Solution Overview
Problem
Existing solid-state imaging devices face sensitivity differences due to manufacturing errors, such as positional shifts of microlenses, leading to varying pixel output values across devices of the same model, affecting phase difference detection accuracy and image brightness.
Innovation Solution
A solid-state imaging device with a pixel unit where one microlens is formed to coincide with pixel boundaries, coupled with a correction circuit that adjusts sensitivity differences between pixels using a correction coefficient, ensuring consistent output across devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If one microlens is formed for multiple pixels to detect phase difference, then phase difference detection function is enabled, but sensitivity difference between pixels occurs due to manufacturing errors
Solution Approach 1:
The patent applies parameter changes by introducing correction coefficients that modify the output signals of individual pixels. These coefficients are calculated based on measured sensitivity differences and are used to adjust the gain or amplitude of each pixel's output, thereby compensating for manufacturing variations and achieving uniform sensitivity across all pixels while maintaining the phase difference detection function
2Manufacturing precision
If correction coefficient is applied to resolve sensitivity difference, then sensitivity uniformity is improved, but pixel output values vary between different solid-state imaging devices
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction coefficients for each individual solid-state imaging device during or after manufacturing. These device-specific coefficients are determined through initial sensitivity measurements and are stored in memory for subsequent use, enabling each device to self-correct its sensitivity variations and achieve consistent output characteristics across the production batch
3Manufacturing precision
If correction is performed using correction coefficient, then sensitivity difference between pixel pair is resolved, but reference value for correction is lacking causing variation in corrected output
Solution Approach 1:
The patent applies feedback by implementing a measurement-correction-verification loop. Correction coefficients are calculated based on measured sensitivity differences, applied to adjust pixel outputs, and then the results are verified through additional measurements. This iterative feedback process ensures that the correction reference is accurately determined and that the correction coefficients effectively eliminate sensitivity differences while maintaining consistent output levels
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 solution effectively suppresses sensitivity differences between solid-state imaging devices, maintaining consistent detection accuracy and image brightness, regardless of manufacturing variations.
Implementation Method 1
In a solid-state imaging device such as a CMOS image sensor, there is a disclosed example in which a phase difference in an object image is detected by dividing a photodiode that partly shields light of a microlens or receives a light flux collected by a microlens
Data Source
AI summary
The present disclosure relates to a solid-state imaging device, a signal processing method therefor, and an electronic apparatus enabling sensitivity correction in which a sensitivity difference between solid-state imaging devices is suppressed.The solid-state imaging device includes a pixel unit in which one microlens is formed for a plurality of pixels in a manner such that a boundary of the microlens coincides with boundaries of the pixels. The correction circuit corrects a sensitivity difference between the pixels inside the pixel unit based on a correction coefficient. The present disclosure is applicable to, for example, a solid-state imaging device and the like.