Image Pickup Apparatus Thinning-Out Circuit for Wide Focus Detection
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Solution Overview
Problem
Conventional image pickup apparatuses face challenges in focus detection, particularly when dealing with large defocus quantities, as they often require a narrow focus detection region to avoid near/far conflicts, which can lead to confusion between focusing on near and far objects, and they lack efficient methods to utilize a wide focus detection region without increasing circuit complexity or computation time.
Innovation Solution
The image pickup apparatus incorporates an optical imaging system, an image pickup device with pixels for both photography and focus detection, a defocus quantity calculation section, and a thinning-out section. This configuration calculates defocus based on phase differences between signals from different pupil regions and thins out unused signals, allowing for a wide focus detection region even during large defocus, without increasing circuit scale or computation time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a narrow focus detection region is used to avoid near/far conflict, then focus detection reliability is improved, but focus detection region width is reduced
Solution Approach 1:
The focus detection pixels are segmented into multiple pupil regions (first pupil region and second pupil region) within the image pickup device. This segmentation allows the system to detect phase differences between light fluxes from different pupil regions, enabling reliable focus detection across a wider focus detection region without causing near/far conflict confusion.
Solution Approach 2:
The image pickup device performs dual functions: it captures images for photography while simultaneously detecting focus information using dedicated focus detection pixels. This multi-functionality eliminates the need for a separate focus detection sensor, allowing the system to use a wide focus detection region without increasing device complexity.
2Area of stationary object
If a wide focus detection region is used, then focus detection region width is improved, but near/far conflict detection accuracy deteriorates
Solution Approach 1:
By dividing the focus detection pixels into multiple pupil regions, the system can accurately measure phase differences even across a wide focus detection region. The segmentation of pupil regions provides spatial information that resolves near/far conflict, maintaining measurement precision while expanding the detection region width.
Solution Approach 2:
The multiple pupil regions act as intermediaries that provide additional information for resolving focus detection ambiguity. By comparing phase differences from different pupil regions, the system can distinguish between near and far objects even when they are within the wide focus detection region, thereby maintaining accuracy.
3Measurement precision
If all focus detection signals are processed, then focus detection accuracy is improved, but computation time and circuit complexity increase
Solution Approach 1:
The thinning-out section extracts and processes only the necessary focus detection signals from the multiple pupil regions, discarding redundant information. This selective extraction maintains focus detection accuracy by preserving essential phase difference data while significantly reducing computation time and circuit complexity.
Solution Approach 2:
Instead of processing all focus detection signals equally, the system applies partial action by selectively processing signals from specific pupil regions based on the defocus quantity. This approach achieves sufficient focus detection accuracy without the excessive computation and circuit complexity that would result from processing all signals fully.
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 enables efficient focus detection across a wide region even during large defocus, maintaining low circuit complexity and computation time, while eliminating the need for a separate focus detection sensor, thus improving autofocus functionality.
Implementation Method 1
an image pickup device including a plurality of pixels that photoelectrically converts the object image
Data Source
AI summary
An image pickup apparatus includes: an optical imaging system; an image pickup device; a defocus quantity calculation circuit for calculating a defocus quantity based on a phase difference between a plurality of signals for focus detection obtained from a plurality of pixels for focus detection that respectively receive a light flux that has passed through a different pupil region of the optical imaging system; a focusing section for driving the optical imaging system so as to achieve an in-focus state in accordance with the calculated defocus quantity; and a thinning-out circuit for thinning out a plurality of signals for focus detection that are not used for calculating the defocus quantity, based on an analysis result of a signal component of an object image.