CMOS Image Sensor Clock Switching for Low-Power Sensing
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Solution Overview
Problem
There is no existing solid-state imaging apparatus that can transition from a sensing mode to an imaging mode by switching from a self-running operation with an internal clock to an external clock when a moving body is detected, which is necessary for applications like surveillance cameras, and this transition is challenging due to power consumption and frequency precision issues.
Innovation Solution
A solid-state imaging apparatus with an A/D conversion unit and an oscillator that generates a second internal clock with a lower frequency than the first internal clock, allowing the A/D conversion unit to operate with reduced resolution and power consumption in sensing mode, and switching to a higher frequency internal clock during imaging mode for improved resolution and power management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the A/D conversion unit operates with high resolution using the first internal clock, then image quality is improved, but power consumption increases
Solution Approach 1:
The system dynamically switches between two operating modes: sensing mode using the second internal clock with lower frequency and reduced A/D conversion resolution for low power consumption, and imaging mode using the first internal clock with higher frequency and full A/D conversion resolution for high image quality. This dynamic adaptation resolves the contradiction by allowing the system to operate at different performance levels based on实际需求
Solution Approach 2:
The invention changes the operating parameters of the A/D conversion unit by switching between different internal clock frequencies (first internal clock for imaging, second internal clock for sensing) and adjusting A/D conversion resolution accordingly. This parameter change enables the system to achieve both low power consumption and high image quality at different times, resolving the inherent contradiction
2Extent of automation
If the solid-state imaging apparatus operates in sensing mode with internal clock, then autonomous operation is achieved, but frequency precision deteriorates
Solution Approach 1:
The invention introduces an oscillator as an intermediary component that generates the second internal clock specifically for sensing mode operation. This intermediary enables autonomous operation without external clock supply while maintaining acceptable frequency precision for sensing applications, resolving the contradiction between autonomy and precision
3Use of energy by moving object
If the oscillator generates a second internal clock with lower frequency, then power consumption is reduced, but A/D conversion resolution decreases
Solution Approach 1:
The system dynamically adjusts A/D conversion resolution based on the operating mode: in sensing mode, it operates with lower resolution acceptable for detection purposes, while in imaging mode, it switches to full resolution for high-quality image capture. This dynamic adjustment resolves the contradiction between power consumption and resolution
Data Source
AI summary
The present disclosure relates to a solid-state imaging apparatus and electronic equipment which can realize operation with lower power consumption in a sensing mode. A solid-state imaging apparatus has an A/D conversion unit that A/D converts a pixel signal and an oscillator that generates a second internal clock with a frequency lower than that of a first internal clock obtained by multiplying an external clock, in which the A/D conversion unit is configured to operate, when operating by the second internal clock, with resolution lower than resolution of A/D conversion when operating by the first internal clock. The present disclosure can be applied to, for example, a CMOS image sensor.