Variable-Delay Pixel Timing to Shorten Photon Detection Dead Time
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Solution Overview
Problem
Current time measurement devices face challenges in minimizing the dead time after detecting a photon, which hinders efficient measurement processes.
Innovation Solution
Incorporating a pixel with a light receiving element and a delay circuit having a variable delay time, allowing for output of pulse signals corresponding to the delay time in one mode and oscillation signals through a ring oscillator in another mode, enabling time measurement processing that shortens dead time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a light receiving element is used to detect photons in a TOF measurement system, then light detection capability is improved, but dead time increases making it difficult to detect subsequent photons
Solution Approach 1:
The invention divides the pixel into two independent operational modes: a first operation mode for precise light detection using the light receiving element, and a second operation mode for rapid reset using the ring oscillator. This segmentation allows the system to switch between high-precision measurement and quick recovery states, effectively reducing dead time while maintaining detection capability.
Solution Approach 2:
The ring oscillator generates periodic clock signals that control the timing and reset sequence of the pixel circuit. By using periodic oscillation to systematically manage the transition between detection and reset states, the system achieves regular, predictable dead time cycles that can be optimized for minimum duration while maintaining measurement accuracy.
2Adaptability or versatility
If a delay circuit with variable delay time is added to control pulse width, then time measurement flexibility is improved, but device complexity increases
Solution Approach 1:
The delay circuit is designed to serve multiple functions: it controls the pulse width in the first operation mode for accurate time measurement, and simultaneously provides timing control for the ring oscillator in the second operation mode. This multi-functionality reduces the need for separate dedicated circuits, thereby limiting the increase in overall device complexity while maintaining high adaptability.
Solution Approach 2:
The delay circuit features variable delay time that can be adjusted to optimize performance for different measurement requirements. By changing the delay parameter rather than adding complex hardware for each measurement scenario, the system achieves high flexibility with minimal increase in structural 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 allows for reduced dead time in time measurement devices, enhancing measurement efficiency by enabling precise timing adjustments and simplified circuit configurations.
Implementation Method 1
a light receiving element... configured to detect reflected light
Data Source
AI summary
A time measurement device according to the present disclosure includes: a pixel that includes a light receiving element and a delay circuit having a variable delay time, is configured to output, as an output signal, a pulse signal that includes a received-light pulse having a pulse width corresponding to the delay time in a first operation mode, and is configured to have a ring oscillator with use of the delay circuit and configured to output, as the output signal, an oscillation signal in the ring oscillator in a second operation mode; and a time measurement section that is configured to perform time measurement processing on the basis of the output signal.