Oxide Semiconductor Touch Sensor for Low Power Display

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing display devices face challenges in achieving low power consumption and high visibility, especially in bright environments, while also providing a novel user interaction method for inputting handwritten information.

Innovation Solution

An information terminal is designed with a display panel incorporating a light-emitting element, a reflective liquid crystal element, and a touch sensor using oxide semiconductor transistors, where the touch sensor senses user input and displays it using the light-emitting element, allowing for low power consumption and high visibility through the use of oxide semiconductor transistors with low off-state current.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a light emission type element is used for display, then visibility in dark environments is improved, but power consumption increases

Engineering Contradiction:

ImprovevisibilityVSAvoidpower consumption

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The display device dynamically switches between reflection-type and light emission type display modes based on ambient light conditions. A light sensor detects environment light intensity, and a control circuit automatically selects the appropriate display type, enabling the system to adapt its power consumption and visibility characteristics to match current usage conditions.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the operational parameter of the display element from fixed light emission mode to variable mode between reflection and light emission. By adjusting the display type parameter based on ambient light levels, the system optimizes the balance between visibility and power consumption.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If a reflection-type element is used for display, then power consumption is reduced, but visibility in dark environments deteriorates

Engineering Contradiction:

Improvepower consumptionVSAvoidvisibility

Core Design Contradiction:

Use of energy by moving objectVSIllumination intensity

Solution Approach 1:

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the operational parameter of the display element from fixed reflection mode to variable mode between reflection and light emission. By adjusting the display type parameter based on ambient light levels, the system optimizes the balance between power consumption and visibility.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If oxide semiconductor transistors are used in the touch sensor, then power consumption is reduced, but sensing accuracy may deteriorate

Engineering Contradiction:

Improvepower consumptionVSAvoidsensing accuracy

Core Design Contradiction:

Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The touch sensor uses a photodiode as an intermediary element that converts light changes (caused by touch) into electrical signals. The photodiode's high photosensitivity compensates for the lower electron mobility of oxide semiconductor transistors, maintaining sensing accuracy while enabling low power consumption operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention changes the material parameter of the transistor from conventional semiconductor to oxide semiconductor, which has lower off-state current but lower electron mobility. This parameter change is compensated by optimizing the photodiode characteristics and circuit design to maintain overall sensing performance.

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 an information terminal with reduced power consumption and high visibility, allowing for efficient display of user input in bright environments by utilizing oxide semiconductor transistors to minimize power usage and enhance sensing accuracy.

Implementation Method 1

The touch sensor includes a photodiode, a second transistor, and a third transistor

Methodology Applied

Scientific EffectPhotoelectric effect: Photoelectric Effect

Implementation Method 2

a light-emitting element

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS10853587B2Information terminal

Publication Date: 2020.12.01 SEMICON ENERGY LAB CO LTD

AI summary

An information terminal with low power consumption is provided. The information terminal includes a liquid crystal element, a light-emitting element, a first transistor, and a touch sensor. The touch sensor includes a photodiode, a second transistor, and a third transistor. The first transistor has a function of controlling a current flowing through the light-emitting element. The photodiode is electrically connected to a gate of the third transistor through the second transistor. A gate of the first transistor is electrically connected to the gate of the third transistor through at least one transistor.