Image Sensor Photo Gate Controller Delay Circuits
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Solution Overview
Problem
Time-of-flight (ToF) based image sensors face challenges in accurately measuring distance due to reading noise in the information generated, which affects the precision of depth information obtained.
Innovation Solution
The implementation of a photo gate controller circuitry with first and second delay circuits that generate delayed clock signals, allowing pixels to selectively receive these signals to reduce noise in depth information by compensating for phase differences and tilt in depth measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single delay circuit is used to generate photo gate signals for all pixels, then the device complexity is reduced, but measurement precision deteriorates due to reading noise and tilt in depth information
Solution Approach 1:
The photo gate controller circuitry is divided into multiple delay circuits (first delay circuit, second delay circuit, third delay circuit) that independently generate photo gate signals for different pixel groups. This segmentation allows each delay circuit to be optimized for specific timing requirements, reducing reading noise and tilt in depth information while maintaining manageable device complexity through modular architecture
Solution Approach 2:
Different delay circuits provide different delay characteristics tailored to specific pixel groups. The first delay circuit provides a first delay time for first pixel groups, the second delay circuit provides a second delay time for second pixel groups, and the third delay circuit provides a third delay time for third pixel groups. This local optimization of timing characteristics improves depth information accuracy for each region while keeping the overall system complexity controlled
2Reliability
If multiple delay circuits with different delay times are implemented, then reading noise in depth information is reduced, but the device complexity increases
Solution Approach 1:
The pixel array is divided into multiple pixel groups (first pixel groups, second pixel groups, third pixel groups) that are separately controlled by different delay circuits. This segmentation enables independent optimization of timing for each group, reducing reading noise through differential timing while maintaining device complexity at acceptable levels through systematic organization
Solution Approach 2:
The multiple delay circuits serve universal functions of generating photo gate signals for different pixel groups, but with specialized timing characteristics. Each delay circuit can be configured with different delay times to accommodate various pixel group requirements, providing both specialization and universality in the photo gate controller circuitry
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 enhances the accuracy of distance measurement by minimizing noise and correcting depth measurement tilts, leading to improved precision in determining object distances.
Implementation Method 1
The pixel signal may correspond to a photoelectric signal generated at a photodiode of the pixel
Data Source
AI summary
An image sensor includes a plurality of pixels and photo gate controller circuitry. Each pixel may transmit a pixel signal, corresponding to a photoelectric signal, in response to a photo gate signal in a frame. The photo gate controller circuitry may generate photo gate signals and transmit photo gate signals to the pixels. The photo gate controller circuitry includes a first delay circuit configured to transmit first delay clock signals each being delayed with respect to a reference clock signal by a certain amount of time and a second delay circuit configured to transmit second delay clock signals each being delayed with respect to the reference clock signal by a certain amount of time. The pixels are each configured to selectively receive signals, as the photo gate signals, among the delay clock signals output from the first delay circuit and the delay clock signals output from the second delay circuit.