Multipurpose Inductor Driver Circuit for Time-of-Flight Cameras

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Solution Overview

Problem

Existing driver circuits for light sources, particularly in range finding devices and time of flight cameras, are inefficient due to the need for complex buck-boost systems and additional pulsating laser drivers.

Innovation Solution

A driver circuitry utilizing a single inductor for both buck conversion and high-speed pulse driving, eliminating the need for additional storage capacitors and reducing power loss by leveraging the parasitic resistance of the inductor, allowing efficient power conversion from battery to laser with a compact and cost-effective design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a complex buck-boost system with four switches is used for driver circuits, then the circuit can provide power conversion, but the efficiency deteriorates due to additional components and power loss

Engineering Contradiction:

Improvepower conversion capabilityVSAvoidpower loss

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The patent combines the buck converter inductor and the laser driver inductor into a single shared inductor. This merging eliminates the need for separate inductors and reduces the total number of switches required, thereby decreasing power loss while maintaining both power conversion and high-speed pulse driving capabilities.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single inductor is designed to serve multiple functions: it acts as the energy storage element for the buck converter to provide average current, and simultaneously serves as the pulse generation element for driving the laser at high speeds. This multi-functionality reduces component count and improves efficiency.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Use of energy by moving object

If additional storage capacitors are added to the driver circuitry, then the power conversion can be improved, but the device complexity increases

Engineering Contradiction:

Improvepower conversion efficiencyVSAvoidcircuit complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The single inductor performs dual roles as both the buck converter energy storage element and the laser driver pulse generation element. This eliminates the need for additional storage capacitors and other auxiliary components, reducing circuit complexity while maintaining efficient power conversion.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The inductor's inherent parasitic resistance is utilized to generate the pulse driving signal for the laser, eliminating the need for separate pulse generation circuits and storage capacitors. The circuit uses its own components to serve multiple functions without requiring external additions.

Inventive Principle:

Principle #25Self-service

3Loss of energy

If a single inductor is used for both buck conversion and pulse driving, then the power loss is reduced, but the measurement precision requirement increases for maintaining efficiency

Engineering Contradiction:

Improvepower lossVSAvoidefficiency monitoring precision

Core Design Contradiction:

Loss of energyVSMeasurement precision

Solution Approach 1:

The patent incorporates a comparator that monitors the voltage across the sensing resistor (which is proportional to the inductor current) and compares it with a reference voltage. This feedback mechanism allows precise control of the switching signals to maintain optimal efficiency while utilizing the single inductor for both functions.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent uses electronic feedback control through comparators and switching signals to precisely manage the single inductor's dual functions, replacing what would otherwise require complex mechanical or analog adjustment mechanisms to optimize performance.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

The solution achieves high efficiency in energy conversion and precise distance measurements with reduced power dissipation, enabling strong, short light bursts and improved background light rejection in time-of-flight applications.

Implementation Method 1

an inductor configured to be used both as inductor of a buck convertor, and to provide high-speed pulse driving of a load

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

reducing power loss by leveraging the parasitic resistance of the inductor

Methodology Applied

Scientific EffectJoule heating: Joule Heating

Data Source

PatentUS10250011B2Driver circuitry and electronic device including a multipurpose inductor

Publication Date: 2019.04.02 SONY SEMICON SOLUTIONS CORP

AI summary

Driver circuitry including an inductor configured to be used both as an inductor of a buck converter and to provide high-speed pulse driving of a load. The driver circuitry includes the buck converter, which includes a first switch, a second switch and a comparator configured to drive the first switch and the second switch. The inductor is connected between the first switch and the second switch of the buck converter and the load and supplies current to drive the load.