Oxide Semiconductor Transistors for Low-Power Contactless Charging

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Solution Overview

Problem

Portable electronic devices that rely on contactless charge by electromagnetic induction face challenges with power supply durability and risk of contact failure or leakage, requiring reduced power consumption to operate effectively without metal terminals for charging.

Innovation Solution

A portable electronic device design incorporating a reflective liquid crystal display, a rechargeable battery capable of contactless charging, and a nonvolatile semiconductor memory device with transistors using oxide semiconductors, which eliminates the need for metal terminals and reduces power consumption by employing a solar cell and efficient power management circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If contactless charge by electromagnetic induction is used, then durability and contact failure risk are improved, but power supply capacity is reduced

Engineering Contradiction:

ImprovedurabilityVSAvoidpower supply capacity

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent changes the material parameter of the transistor by using oxide semiconductor instead of conventional semiconductor materials. This material substitution enables extremely low off-state current (lower than or equal to 100 aA/μm), which dramatically reduces power consumption and allows the device to operate effectively with the limited power supplied through contactless charging while maintaining durability benefits

Inventive Principle:

Principle #35Parameter changes

2Power

If metal terminals are provided for charging, then power supply capacity is improved, but risk of contact failure and leakage increases

Engineering Contradiction:

Improvepower supply capacityVSAvoidcontact failure risk

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent replaces the mechanical contact system (metal terminals and contacts) with a contactless electromagnetic induction charging system. This substitution eliminates physical contact components that are prone to failure, corrosion, and leakage, thereby improving reliability while the low power consumption of oxide semiconductor transistors ensures adequate power supply capacity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Use of energy by moving object

If power consumption is reduced to operate with contactless charge, then operation capability with low power is improved, but device performance may be limited

Engineering Contradiction:

Improvepower consumptionVSAvoiddevice performance

Core Design Contradiction:

Use of energy by moving objectVSProductivity

Solution Approach 1:

The patent changes the fundamental material parameter of the transistor to oxide semiconductor, which inherently provides extremely low off-state current characteristics. This material change enables the device to achieve ultra-low power consumption without sacrificing essential device performance, as the oxide semiconductor maintains adequate on-state current and switching characteristics necessary for normal device operation

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

The solution enables reliable operation of portable electronic devices without metal terminals, minimizing the risk of contact failure and leakage, while reducing power consumption even when power supplied through contactless charge is low, ensuring efficient and durable charging.

Implementation Method 1

capable of charge by contactless charge

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

The oxide semiconductor is intrinsic or substantially intrinsic, and the off-state current per unit channel width of a transistor is lower than or equal to 100 aA/μm

Methodology Applied

Scientific EffectIntrinsic semiconductor property:

Data Source

PatentUS12001241B2Portable electronic device having transistor comprising oxide semiconductor

Publication Date: 2024.06.04 SEMICON ENERGY LAB CO LTD

AI summary

A portable electronic device that can operate even when electric power supplied through contactless charge by electromagnetic induction is low is provided. The portable electronic device includes a reflective liquid crystal display which includes a transistor including an oxide semiconductor, a power source portion which includes a rechargeable battery capable of charge by contactless charge, and a signal processing portion which includes a nonvolatile semiconductor memory device. In the portable electronic device, electric power stored in the rechargeable battery is used in the reflective liquid crystal display and the signal processing portion.