Digital Pixel Sensor Threshold Capture for Lower-Power HDR Imaging
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Solution Overview
Problem
Contemporary digital image sensors face a trade-off between power efficiency and dynamic range, as higher dynamic range requirements lead to increased power consumption and potential saturation issues, limiting their performance in applications like augmented and virtual reality.
Innovation Solution
A digital image sensor design that employs single quantization operations and time-based pixel charge threshold processing, using an integrated circuit to determine when sufficient charge is generated and prevent further accumulation, thereby reducing power consumption while maintaining a high dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the charge storage device continuously accumulates charge to increase dynamic range, then the dynamic range is improved, but power consumption increases and saturation occurs
Solution Approach 1:
The integrated circuit performs preliminary comparison of the captured voltage against a threshold voltage value before the charge storage device completes its accumulation. This preliminary action allows the system to determine in advance whether the dynamic range requirement is satisfied, preventing unnecessary continued accumulation that would waste power and cause saturation.
Solution Approach 2:
The system implements a feedback mechanism where the integrated circuit continuously monitors the captured voltage from the charge storage device and compares it to a threshold. Based on this feedback, the system dynamically determines when to stop the quantization operation, ensuring the dynamic range is sufficient while avoiding excessive power consumption and saturation.
2Duration of action of moving object
If the charge storage device accumulates charge for longer periods to capture more light values, then the dynamic range is improved, but saturation and unnecessary power usage occur
Solution Approach 1:
The integrated circuit provides continuous feedback by comparing the captured voltage against the threshold voltage value during the exposure period. This feedback mechanism allows the system to accurately determine when the dynamic range requirement is met, preventing over-exposure that would lead to saturation while still capturing sufficient light values for high dynamic range.
Solution Approach 2:
The system performs a preliminary check of the captured voltage level against the threshold before the full exposure time elapses. This preliminary determination allows the system to stop the accumulation process early if the dynamic range is already sufficient, preventing the harmful saturation effect while maintaining high dynamic range performance.
3Measurement precision
If multiple quantization operations are performed to maintain accuracy, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent extracts only the essential quantization operation needed to achieve sufficient dynamic range by comparing the captured voltage against a threshold voltage value. This single comparison operation replaces multiple complex quantization operations, maintaining measurement precision while significantly reducing device complexity and power consumption.
Solution Approach 2:
The system changes the approach from multiple incremental quantization operations to a single threshold-based comparison. By changing the parameter from repeated quantization cycles to a one-time threshold check, the system achieves the same measurement precision with reduced complexity 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
This approach reduces power consumption while preserving a higher dynamic range, preventing unnecessary power usage and saturation, and enhancing the accuracy of digital image generation.
Implementation Method 1
Each pixel cell may include a photodiode to sense light by converting photons into charge (e.g., electrons or holes)
Data Source
AI summary
In some examples, a sensor apparatus comprises: a pixel cell configured to generate a voltages, the pixel cell including a photodiode configured to generate charge in response to incoming light, and a charge storage device to convert the charge to a voltage; an integrated circuit configured to: determine a first captured voltage converted by the charge storage device during a first time period; compare the first captured voltage to a threshold voltage value; and in response to determining that the first captured voltage meets or exceeds the threshold voltage value: determine first time data corresponding to the first time period; and prevent the charge storage device from further generating a charge; and an analog-to-digital converter (ADC) configured to generate a digital pixel value based on the first captured voltage, and a memory to store the digital pixel value and the first time data.