Active-Pixel Sensor Array Binning for LiDAR Sensitivity
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Solution Overview
Problem
Existing active-pixel sensor arrays face challenges in increasing pixel sensitivity while maintaining image resolution, particularly in applications requiring a large number of pixels in one dimension, such as line scanners and LiDAR systems, due to limitations in semiconductor technology and readout difficulties.
Innovation Solution
The solution involves an active pixel sensor array with a plurality of pixel elements, including photodiodes and floating diffusion regions, where the array is configured to emit alternating short-range and long-range light pulses, allowing for selective detection and calculation of distance using different sensitivity settings, and the array is arranged with multiple photodiodes in columns to maintain high resolution without enlarging the detector's physical dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the active area of each pixel sensor is increased to enhance sensitivity, then pixel sensitivity is improved, but the number of pixels in the detected image is reduced or the size of the entire active-pixel sensor array must be increased
Solution Approach 1:
The patent applies binning technology to combine photodiodes from multiple rows (first row and second row) along the second dimension to increase the effective active area of each pixel sensor. This allows sensitivity enhancement without reducing the number of pixels along the first dimension, thereby maintaining image resolution while improving pixel sensitivity through multi-row photodiode combination.
2Measurement precision
If the dimension of each pixel sensor is increased in the second dimension to maintain resolution along the first dimension, then pixel sensitivity is improved, but technical difficulties related to readout (diffusion length of charge carriers) limit this increase
Solution Approach 1:
The patent merges photodiodes from the first row and second row into combined pixel sensors through binning operation. By coupling corresponding photodiodes from adjacent rows and reading them through a common floating diffusion region, the patent reduces readout complexity while effectively increasing the active area for light detection, thus improving sensitivity without proportionally increasing readout difficulty.
3Measurement precision
If photodiodes are arranged in multiple rows with binning operation to increase sensitivity, then pixel sensitivity is improved, but the resolution along the first dimension is compromised
Solution Approach 1:
The patent segments the pixel array into multiple independent rows along the first dimension, where each row maintains its own photodiode arrangement for high-resolution detection. By combining photodiodes from different rows through binning operation rather than combining photodiodes within the same row, the patent preserves the high-resolution capability along the first dimension while achieving sensitivity enhancement through the second dimension.
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 configuration enhances pixel sensitivity for both short-range and long-range object detection, maintaining image resolution and improving detection accuracy in autonomous vehicle systems by effectively utilizing different sensitivity settings for varying detection requirements.
Implementation Method 1
each pixel containing a photodetector... the at least one photodiode being disposed with respect to the light source, such that the first and second pulses are reflected back from the object towards the at least one photodiode
Data Source
AI summary
A range detector for detecting distance of an object is provided. The detector includes: a light source configured to emit a first light pulse and a second light pulse towards a distant object, the first light pulse being configured for short-range object detection and the second light pulse being configured for long-range object detection; an active pixel sensor having a plurality of pixel elements each of which including at least one photodiode and at least one floating diffusion region configured to receive photoelectric charge from the at least one photodiode, the at least one photodiode being disposed with respect to the light source, such that the first and second pulses are reflected back from the object towards the at least one photodiode; and a controller configured to actuate the light source to selectively emit the first and second light pulses and to determine distance of the object.