Image Sensor Analog Differencing Circuit for Ambient Light Noise Reduction
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Solution Overview
Problem
Conventional image sensors using global shutters require post-processing subtraction of digital image frames to eliminate ambient light noise, which necessitates large digital buffers and increased power consumption.
Innovation Solution
An image sensor employing analog differencing to eliminate ambient light noise by storing and comparing charge amounts during light source on and off periods, eliminating the need for large digital buffers and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If digital buffer is used to store image frames for post-processing subtraction, then ambient light noise can be eliminated through digital image frame subtraction, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces the digital buffer storage system with an analog differencing circuit system. Instead of storing complete digital image frames in a digital buffer and performing subtraction through digital processing, the invention uses analog circuits to directly subtract the ambient light component from the captured image signal in the analog domain, thereby eliminating the need for large digital buffers and reducing device complexity
Solution Approach 2:
The patent changes the domain parameter from digital to analog for the differencing operation. By performing the subtraction operation in the analog domain before digital conversion, the system avoids the need to store and process large amounts of digital data, thus reducing device complexity while maintaining noise elimination capability
2Object-affected harmful factors
If digital buffer is used to store image frames for post-processing subtraction, then ambient light noise can be eliminated, but power consumption increases
Solution Approach 1:
The patent substitutes the power-intensive digital buffer storage and digital processing system with a low-power analog differencing circuit system. The analog circuits perform the subtraction operation directly on the analog image signals before they are converted to digital form, significantly reducing the power consumption associated with digital buffer operations and post-processing
Solution Approach 2:
The patent performs the noise elimination action preliminarily by subtracting the ambient light component in the analog domain before the signals are converted to digital form. This preliminary differencing operation eliminates the need for subsequent digital buffer storage and digital subtraction operations, thereby reducing overall power consumption
3Quantity of substance
If large digital buffer is used to store sensing data, then complete image frames can be stored for processing, but device complexity and power consumption increase
Solution Approach 1:
The patent replaces the large digital buffer storage system with an analog differencing circuit system that processes signals in the analog domain. This substitution eliminates the need to store large amounts of digital image frame data, thereby reducing device complexity while maintaining the capability to eliminate ambient light noise
Solution Approach 2:
The patent extracts and processes only the necessary signal components in the analog domain before digital conversion. By performing differencing operations on analog signals rather than storing and processing complete digital image frames, the system reduces the quantity of data that needs to be buffered, thus reducing device complexity
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
The solution effectively removes ambient light noise from analog image signals before digital conversion, reducing the need for frame differencing and lowering power consumption, while maintaining image quality.
Implementation Method 1
an optoelectronic conversion circuit 10 configured to store a charge amount Q corresponding to a period of a drive signal
Data Source
AI summary
An image sensor including an optoelectronic conversion circuit, a read circuit, a timing control and a serial interface is provided. The optoelectronic conversion circuit is configured to store a charge amount. The read circuit is coupled to the optoelectronic conversion circuit via a bit line. The timing control is configured to send at least one control signal to control the optoelectronic conversion circuit to store the charge amount and control the read circuit to read the charge amount stored in the optoelectronic conversion circuit. The serial interface is coupled to the timing control and configured to send a trigger signal to the timing control to activate the timing control to send the at least one control signal.