SPAD Pixel Timing Shift for High-Frequency Pulsed Light Detection
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Solution Overview
Problem
SPAD pixels face difficulties in detecting high-frequency pulsed light due to their inability to detect light after avalanche amplification until they are reset.
Innovation Solution
A solid-state imaging apparatus with a drive section that shifts the operation timings of light-receiving elements and a time measurement section to measure the time until light is reflected and received, allowing for the detection of high-frequency pulsed light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SPAD pixel uses avalanche amplification to detect light, then detection sensitivity is improved, but the pixel cannot detect light after avalanche amplification until reset, reducing detection speed
Solution Approach 1:
The pixel array is divided into multiple pixel groups, where each group contains pixels that operate in synchronized phases. By segmenting the detection process across multiple groups with different phase timings, the system achieves both high sensitivity (through avalanche amplification in each pixel) and high speed (through parallel processing across groups), resolving the contradiction between detection sensitivity and detection speed.
2Productivity
If SPAD pixel operates continuously to detect high-frequency pulsed light, then detection capability for high-frequency light is improved, but the reset time after avalanche amplification limits the frame rate
Solution Approach 1:
The pixel groups operate with periodic phase shifts, where each group sequentially activates at different time intervals. This periodic operation allows pixels to complete avalanche amplification and reset before the next detection cycle begins, eliminating the constraint of reset time on frame rate while maintaining the ability to detect high-frequency pulsed light.
3Measurement precision
If single pixel detects light sequentially, then detection accuracy is maintained, but the time required for distance measurement increases
Solution Approach 1:
Multiple pixel groups are merged into a single integrated detection system that processes distance measurement data in parallel. Each pixel group contributes to the overall distance measurement simultaneously, combining their individual measurements to achieve both high accuracy (through multiple measurements) and reduced time (through parallel processing), resolving the contradiction between measurement precision and measurement time.
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
Enables the detection of high-frequency pulsed light, improving the frame rate and reducing the time required for distance measurement in the distance measurement system.
Implementation Method 1
a light-receiving element that converts received light into an electric signal
Implementation Method 2
avalanche amplification occurs when a photon enters into a PN junction region having a high electric field with a voltage much larger than a breakdown voltage applied
Data Source
AI summary
It is an object to provide a solid-state imaging apparatus and a distance measurement system that can detect high-frequency pulsed light. The solid-state imaging apparatus includes a plurality of pixels, a drive section, and a time measurement section. Each of the plurality of pixels has a light-receiving element that converts received light into an electric signal. The drive section drives the plurality of pixels by shifting operation timings of the light-receiving elements. The time measurement section is provided such that the electric signal is input from each of the plurality of pixels and measures the time until light emitted from a light source is reflected by a subject and received by the light-receiving element on the basis of the input of the electric signal.