Imaging Device Analog Digital Mode Switching
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Solution Overview
Problem
Imaging devices, particularly those using CMOS image sensors, face high power consumption due to extensive digital and analog processing requirements, especially in applications like security cameras where continuous monitoring is needed, leading to increased energy usage and potential inefficiencies.
Innovation Solution
The implementation of an imaging device with a pixel, digital circuit, and analog processing circuit including a constant current circuit, current comparison circuit, and control circuit, which allows for differential data processing with reduced power consumption by switching between analog and digital operation modes based on detection signals, thereby minimizing unnecessary processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous digital and analog processing is performed for monitoring, then detection capability is improved, but power consumption increases
Solution Approach 1:
The imaging device alternates between a first operation mode (analog processing only) and a second operation mode (digital and analog processing) based on whether changes are detected in the imaging data. This periodic switching between processing intensities reduces overall power consumption while maintaining detection capability when needed.
Solution Approach 2:
The device changes operational parameters by switching between two distinct operation modes. In the first mode, only analog processing is performed with lower power consumption. When changes are detected, the device transitions to the second mode where digital processing is activated, increasing power consumption but also detection capability. This dynamic parameter adjustment resolves the contradiction between continuous monitoring and power efficiency.
2Measurement precision
If extensive digital processing is performed on imaging data, then image analysis accuracy is improved, but processing time increases
Solution Approach 1:
The device performs partial digital processing only when necessary - specifically, digital processing is activated only when changes are detected in the imaging data. For normal monitoring conditions without detected changes, the device relies on analog processing alone, reducing processing time while maintaining sufficient accuracy for change detection applications.
3Speed
If analog processing circuit operates continuously, then real-time detection is improved, but power consumption increases
Solution Approach 1:
The analog processing circuit operates continuously in the first operation mode to maintain real-time detection capability. When changes are detected, the device switches to the second operation mode where digital processing is activated. This periodic operation pattern allows the analog circuit to remain ready for real-time detection while reducing overall power consumption by activating additional processing only when needed.
Data Source
AI summary
An imaging device includes a pixel; a digital circuit; and an analog processing circuit including a constant current circuit, a current comparison circuit, and a control circuit. The pixel is capable of outputting differential data. The constant current circuit is capable of supplying a first current corresponding to the differential data, in accordance with a first control signal. The current comparison circuit is capable of supplying a second current that flows through the constant current circuit in accordance with a change in the differential data. The current comparison circuit has a function of setting a determination signal active depending on whether to supply the second current to the constant current circuit. The control circuit has a function of controlling the constant current circuit and the current comparison circuit to stop their functions as the determination signal becomes active. The digital circuit operates as the determination signal becomes active.