Intermittent Focus Detection for Power Reduction
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Solution Overview
Problem
Existing imaging apparatuses face challenges in performing focus detection while minimizing power consumption, particularly when using multiple photodiodes for each pixel, which can lead to increased signal reading and power consumption for focus detection calculations.
Innovation Solution
An imaging apparatus with a drive unit for focus adjustment, a calculation unit for phase difference detection, and a control unit that intermittently performs focus detection calculations across multiple image frames, reducing power consumption by optimizing focus detection operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus detection is performed by acquiring signals from multiple photodiodes for each pixel, then focus detection capability is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic focus detection by performing correlation calculations only at specific intervals (e.g., every Nth frame) rather than continuously for every frame. The control unit selectively activates the calculation unit to compute correlation values between first and second image signals only at these periodic intervals, thereby maintaining focus detection capability while significantly reducing power consumption during video capture operations.
2Speed
If focus detection calculation is performed for every image frame, then focus adjustment responsiveness is improved, but processing load and power consumption increase
Solution Approach 1:
The system performs correlation-based focus detection calculations at periodic intervals (e.g., once every N frames) rather than continuously for each frame. The control unit manages the calculation unit to execute correlation computations only at these predetermined intervals, reducing processing load and power consumption while maintaining adequate focus responsiveness for video capture applications.
Solution Approach 2:
The patent applies partial action by performing focus detection on only a subset of image frames rather than all frames. The correlation calculation is executed selectively on specific frames (e.g., every other frame or every Nth frame), providing sufficient focus information for video capture without the excessive processing burden of analyzing every single frame, thus optimizing the balance between responsiveness and power consumption.
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 focus detection during image capturing while minimizing power consumption by selectively performing focus detection calculations, thereby reducing overall power usage and maintaining efficient focus adjustment capabilities.
Implementation Method 1
an imaging element having a plurality of photoelectric conversion units included in each pixel
Data Source
AI summary
An imaging apparatus includes an imaging element for outputting focus detecting signals. A DFE performs phase difference detection-type focus detecting calculation using an output signal of the imaging element. A CPU controls a focus drive circuit depending on the result of calculation and a focus lens is driven so as to perform a focus adjusting operation. The CPU controls the DFE to intermittently execute focus detecting calculation at a predetermined frequency set for a plurality of image frames. In the first mode, AF processing is executed at a rate of once in a few frames and the operation of a circuit unit for performing correlation calculation or the like is stopped in a frame period during which no focus detecting calculation is performed, whereas in the second mode, AF processing is executed for each frame so as to perform a focus adjusting operation following the movement of an object.