Sinusoidal Optical Emission Circuit via Phase-Shifted Group Activation

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Solution Overview

Problem

Existing optical transmission circuits face challenges in efficiently generating sinusoidal optical signals for indirect time-of-flight applications, particularly in achieving high frequency and high average power with sinusoidal amplitude variation, which is simpler to measure than slotted optical signals.

Innovation Solution

A method involving an array of optical sources divided into groups, with sequential and periodic activation/deactivation using control signals phase-shifted by Pi/N, generating sinusoidal optical signals by varying the total current flowing through the sources, ensuring symmetry and high power transmission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If optical sources are activated continuously to maintain high average power, then power transmission is improved, but the ability to generate sinusoidal amplitude variation is degraded

Engineering Contradiction:
Improveaverage powerVSAvoidsinusoidal amplitude variation
Core Design Contradiction:
PowerVSEase of operation

Solution Approach 1:

The patent applies periodic action by sequentially activating and deactivating groups of optical sources in a periodic manner. The optical sources are divided into multiple groups that are activated in sequence with phase shifts, creating a periodic modulation pattern that generates sinusoidal amplitude variation while maintaining high average power transmission.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent segments the optical sources into multiple independent groups that can be controlled separately. This segmentation allows each group to be activated in sequence with specific duty cycles and phase shifts, enabling the generation of sinusoidal amplitude variation while maintaining overall high power transmission through coordinated group activation.

Inventive Principle:
Principle #1Segmentation

2Ease of operation

If optical sources are divided into multiple groups for sequential activation, then sinusoidal signal generation is improved, but device complexity is worsened

Engineering Contradiction:
Improvesinusoidal signal generationVSAvoidcontrol circuit complexity
Core Design Contradiction:
Ease of operationVSDevice complexity

Solution Approach 1:

The control circuit generates periodic control signals with specific duty cycles (e.g., 50%) and phase shifts (e.g., Pi/N for N groups) to sequentially activate the optical source groups. This periodic control approach simplifies the generation of sinusoidal amplitude variation by using regular, repeating patterns rather than complex arbitrary waveforms.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent changes key parameters of the control signals, specifically the duty cycle (set to 50% for symmetry) and phase shift (Pi/N between adjacent groups), to optimize the generation of symmetric sinusoidal signals. These parameter optimizations simplify the control circuit design by establishing fixed, standardized signal characteristics.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If duty cycle is set to 1/2 for control signals, then symmetry of sinusoidal signal is improved, but flexibility in power adjustment is worsened

Engineering Contradiction:
Improvesignal symmetryVSAvoidpower adjustment flexibility
Core Design Contradiction:
Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The patent sets the duty cycle parameter to a fixed value of 1/2 (50%) to ensure symmetry in the generated sinusoidal optical signal. This fixed parameter approach prioritizes signal quality and symmetry over flexible power adjustment, creating a stable and predictable signal characteristics suitable for precise phase shift measurements.

Inventive Principle:
Principle #35Parameter changes

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 approach enables the transmission of sinusoidal optical signals with high frequency and high average power, maintaining symmetry and reducing complexity, effectively addressing the measurement challenges in indirect time-of-flight applications.

Implementation Method 1

a method for controlling an array of M optical sources... generating an optical signal whose amplitude varies in stages according to a sinusoidal evolution

Methodology Applied
Scientific EffectLight emission from optical sources: Light Emitting Diode

Data Source

PatentEP3336980B1Sinusoidal optical emission method, and corresponding circuit
Publication Date: 2019.08.28 STMICROELECTRONICS (ALPS) SAS
  • EP3336980B1 patent drawingFigure 1~3
  • EP3336980B1 patent drawingFigure 4
  • EP3336980B1 patent drawingFigure 5~6

AI summary

The method for controlling an array (3) of M optical sources, the M optical sources being distributed into N groups (G1 to G4), with N less than M, comprises cycles of respective and sequential activation/deactivation of all the optical sources of the N groups from N control signals (SC1 to SC4) in periodic squares successively mutually phase-shifted by Pi/N and all having the same period, each control signal (SC1 to SC4) having a first state, a second state, and a duty cycle (R) of 1/2, each group (G1 to G4) being activated when the corresponding control signal (SC1 to SC4) is in its first state and deactivated when the control signal (SC1 to SC4) is in its second state,the number of optical sources in each group (G1 to G4) and the ordering of the groups (G1 to G4) in the activation/deactivation sequence being chosen so as to generate an optical signal (5) whose amplitude varies in steps according to a sinusoidal evolution.