Imaging Apparatus Phase Difference Detection Autofocus
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Solution Overview
Problem
Existing digital cameras face challenges in quickly detecting focus, particularly with video AF, which requires shifting the focus lens back and forth, and in single-lens reflex cameras, the movable mirror obstructs light during phase difference detection AF, limiting exposure of the imaging device.
Innovation Solution
An imaging apparatus that includes a phase difference detection section capable of receiving light while the imaging device is exposed, allowing for phase difference detection AF without moving the mirror, and a control section to adjust electrical charge storage time for different shooting modes, enabling smooth AF in moving picture shooting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If phase difference detection AF is used to achieve fast focus detection, then focus detection speed is improved, but the movable mirror must be moved to block light during AF operation
Solution Approach 1:
The patent extracts the light-guiding function from the movable mirror by introducing a separate light guide component that channels light from the lens to both the imaging device and phase difference detection section simultaneously, eliminating the need for the mirror to block light during AF operations
Solution Approach 2:
The optical path is segmented into multiple independent channels: one leading to the imaging device for exposure and another leading to the phase difference detection section for focus detection, allowing both functions to operate simultaneously without interference
2Volume of moving object
If video AF is used to reduce camera size by eliminating the movable mirror, then device compactness is improved, but focus detection speed decreases due to the need to shift the focus lens back and forth
Solution Approach 1:
The imaging device is segmented into functional zones with light transmitting portions that allow simultaneous operation of imaging and phase difference detection, enabling fast focus detection without requiring the focus lens to shift back and forth
Solution Approach 2:
The patent utilizes the thickness dimension of the imaging device substrate to create light transmitting portions that channel light to the phase difference detection section located on the back surface, enabling optical path separation without increasing planar footprint
3Measurement precision
If the movable mirror is positioned to block light during phase difference detection AF, then phase difference detection accuracy is improved, but the imaging device cannot be exposed to light during AF operation
Solution Approach 1:
The optical path is divided into separate channels using light guide structures, allowing one channel to deliver light to the imaging device for exposure while another channel delivers light to the phase difference detection section for accurate focus detection, eliminating the need for the mirror to block light
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 faster and more accurate autofocus using phase difference detection while allowing continuous exposure of the imaging device, improving focus detection speed and accuracy in both still and moving picture shooting modes.
Implementation Method 1
an imaging device for performing photoelectric conversion to convert light from an object into an electrical signal
Data Source
AI summary
An imaging apparatus includes: an imaging device for performing photoelectric conversion to convert light from an object into an electrical signal; a phase difference detection section for receiving the light from the object to the imaging device while the imaging device receives the light, and performing phase difference detection; a focus lens group for adjusting a focus position; a focus lens position detection section for detecting a position of a focus lens; and a control section for calculating an object distance based on an output of the focus lens position detection section and an output of the phase difference detection section and automatically selecting one of a plurality of shooting modes according to the calculated object distance.