Multi-Element Light-Receiving Apparatus with Bias-Based Saturation Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing ToF sensors face challenges in accurately measuring distance due to increased sensitivity leading to detection of ambient light, such as sunlight, which interferes with the measurement of faint reflected light from distant objects.
Innovation Solution
A light-receiving apparatus with multiple light-receiving elements per pixel, controlled by a controller circuit to adjust bias voltage, ensuring that no more than a threshold number of elements detect light simultaneously, thereby preventing saturation and reducing ambient light interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensitivity of the light-receiving apparatus is increased to detect faint reflected light from distant objects, then the detection capability for weak light is improved, but ambient light such as sunlight is also detected, causing interference with accurate distance measurement
Solution Approach 1:
The light-receiving apparatus is divided into multiple light-receiving elements (first, second, and third elements) within a single pixel, each independently detecting light signals. This segmentation allows the system to process different light intensity ranges separately, enabling accurate detection of weak reflected light while filtering out ambient light interference through comparative analysis of signals from multiple elements.
Solution Approach 2:
The patent applies different bias voltages to different light-receiving elements to change their sensitivity parameters. By adjusting the bias voltage, each element can be optimized for specific light intensity ranges, allowing the system to maintain high sensitivity for weak light detection while preventing saturation from ambient light through parameter optimization.
2Measurement precision
If multiple light-receiving elements are used per pixel to improve detection accuracy, then the ability to filter ambient light is enhanced, but the device complexity increases
Solution Approach 1:
The pixel is segmented into multiple light-receiving elements with distinct functional roles. The first element detects both reflected light and ambient light, the second element detects primarily ambient light, and the third element provides additional detection capability. This segmentation enables ambient light subtraction through differential measurement, improving distance measurement accuracy while maintaining a manageable device structure.
Solution Approach 2:
The control circuit receives signals from multiple light-receiving elements and performs differential processing to subtract ambient light components. By using feedback from the second element (which primarily detects ambient light) to compensate for the first element's signal, the system achieves accurate distance measurement while managing the complexity of having multiple elements through intelligent signal processing.
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 allows for accurate distance measurement by ensuring the light-receiving elements are not saturated, effectively filtering out ambient light and enhancing the detection of weak reflected light.
Implementation Method 1
M light-receiving elements corresponding to one pixel in a light-receiving unit having a plurality of pixels
Implementation Method 2
By operating in Geiger mode using an avalanche photodiode as a light-receiving apparatus, it is possible to obtain a highly sensitive light-receiving apparatus capable of detecting faint light
Data Source
AI summary
A light-receiving apparatus has M (M is greater than 2) light-receiving elements corresponding to one pixel, and controller circuitry configured to control a bias voltage of the M light-receiving elements in accordance with a condition that the number of light-receiving elements of the M light-receiving elements simultaneously detecting light within a first period is less than N (N is an integer equal to or greater than 2 and less than M).