ToF Sensor Pixel Array With Overflow Transistor for LIDAR
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Solution Overview
Problem
Current LIDAR systems using time of flight (ToF) sensors face limitations in sensing distance due to limited power in electronic devices, which restricts their range and accuracy, especially when using flash-type light sources that result in leakage currents and shading phenomena.
Innovation Solution
The electronic device incorporates a ToF sensor with a pixel array and a light source that emits light signals to specific areas of an object, utilizing an optical device to control light projection directions and a pixel array with overflow transistors to remove charges, allowing for efficient scanning and demodulation of light signals based on scanning direction, thereby enhancing sensing capabilities without the limitations of flash-type light sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If flash-type light sources are used in LIDAR systems, then illumination intensity is improved, but leakage currents and shading phenomena increase
Solution Approach 1:
The pixel array is divided into multiple pixel blocks, where each pixel block contains multiple pixels arranged in a specific pattern. This segmentation allows selective activation of different pixel blocks for different scanning directions, reducing the overall leakage current and shading effects while maintaining sufficient illumination intensity for distance measurement.
Solution Approach 2:
Different pixel blocks are configured with different orientations of photo transistor arrays to match different scanning directions. This local quality optimization ensures that each pixel block efficiently detects light signals from its corresponding scanning direction while minimizing interference and harmful effects from other directions.
2Use of energy by moving object
If power consumption is reduced in electronic devices, then energy efficiency is improved, but sensing distance is limited
Solution Approach 1:
The LIDAR system employs periodic scanning operations where different pixel blocks are activated in sequence according to different scanning directions. This periodic action allows the system to concentrate power consumption on active pixel blocks only, reducing overall power consumption while maintaining adequate sensing distance through time-multiplexed detection.
Solution Approach 2:
The system dynamically adjusts operational parameters such as integration time and light source pulse duration based on the active pixel block configuration. By optimizing these parameters for each scanning phase, the system achieves extended sensing distance while minimizing power consumption during each measurement cycle.
3Measurement precision
If multiple pixel blocks are used to cover different areas, then measurement precision is improved, but device complexity increases
Solution Approach 1:
Multiple pixel blocks with different photo transistor array orientations are integrated into a single ToF sensor module. This merging approach enables simultaneous multi-directional scanning capabilities while sharing common control and readout circuitry, thereby improving measurement precision across different areas without proportionally increasing 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
This configuration enables the electronic device to sense distant objects using limited power while reducing leakage currents and shading effects, improving the accuracy and range of LIDAR systems by controlling light projection and demodulation operations.
Implementation Method 1
a light source configured to emit light signals
Implementation Method 2
the light signal may be reflected from the object
Implementation Method 3
Each of the pixels includes a plurality of taps each including a photo transistor
Data Source
AI summary
An electronic device includes a time of flight (ToF) sensor including a pixel array, a light source that emits light signals, and an optical device that projects the light signals to areas of an object which respectively correspond to a plurality of pixel blocks including pixels of the pixel array. Each of the pixels includes a plurality of taps each including a photo transistor, a first transfer transistor connected with the photo transistor, a storage element connected with the first transfer transistor, a second transfer transistor connected with the storage element, a floating diffusion area connected with the second transfer transistor, and a readout circuit connected with the floating diffusion area. An overflow transistor is disposed adjacent to the photo transistor and connected with a power supply voltage.