Low Power Wakeup Detection Circuit for Portable Touch Devices

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Solution Overview

Problem

Portable electronic devices with touch-sensitive displays consume significant power due to periodic scanning required to detect touch events, leading to reduced battery life.

Innovation Solution

A low power wakeup detection circuit that uses force sensing transducers to monitor for touch events at a reduced duty cycle, only switching to full power mode when a predefined force threshold is exceeded, eliminating the need for periodic scanning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If periodic scanning is used to detect touch events on touch-sensitive displays, then touch event detection capability is improved, but power consumption increases

Engineering Contradiction:

Improvetouch event detection capabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent extracts the wake-up detection function from the main touch-sensitive display system by using a separate force sensing transducer that operates independently at low power. This allows the main display scanning to be disabled or reduced while maintaining touch detection capability through the force sensor.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The force sensing transducer continuously monitors for touch events in advance at low power consumption, preparing the system to wake up only when necessary. This preliminary monitoring action eliminates the need for continuous high-power scanning of the touch-sensitive display.

Inventive Principle:

Principle #10Preliminary action

2Speed

If continuous scanning is performed to ensure responsive touch detection, then touch response time is improved, but battery life deteriorates

Engineering Contradiction:

Improvetouch response timeVSAvoidbattery life

Core Design Contradiction:

SpeedVSDuration of action of moving object

Solution Approach 1:

The system uses periodic scanning only when needed (when the force sensing transducer detects a potential touch event), rather than continuous scanning. This periodic activation maintains responsive touch detection while significantly reducing overall power consumption and extending battery life.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The force sensing transducer acts as an intermediary that triggers the main touch detection system only when necessary. This intermediary sensor operates at low power and activates the higher-power scanning system only when a touch event is likely, optimizing both response time and battery life.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If the touch-sensitive display scanning is reduced to save power, then power consumption is improved, but touch event detection reliability deteriorates

Engineering Contradiction:

Improvepower consumptionVSAvoidtouch event detection reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent replaces the electrical scanning mechanism of the touch-sensitive display with a mechanical force sensing transducer. This mechanical sensor can detect physical touch events without requiring electrical scanning, maintaining detection reliability while consuming significantly less power.

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

This solution significantly reduces power consumption by minimizing unnecessary scanning, thereby extending battery life and maintaining responsive touch event detection.

Implementation Method 1

at least one force sensing transducer for measuring force data

Methodology Applied

Scientific EffectForce sensing:

Data Source

PatentEP2315102B1A low power wakeup detection circuit and a portable electronic device having a low power wakeup detection circuit

Publication Date: 2018.01.31 BLACKBERRY LTD

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Figure 3A~3B

AI summary

The present disclosure provides a low power wakeup detection circuit and a portable electronic device having a low power wakeup detection circuit. In accordance with one embodiment, there is provided a portable electronic device, comprising: a housing; a controller received within the housing; a touch-sensitive display having a touch-sensitive overlay, the touch-sensitive display being mechanically constrained by the housing; at least one force sensing transducer located below the touch-sensitive display on an opposite side to the touch-sensitive overlay, the at least one force sensing transducer being connected to the controller and measuring forces applied to the touch-sensitive display; wherein the controller is configured for: initiating a sleep mode from a full power mode in response to a trigger; when in the sleep mode, reading force data measured by the at least one force sensing transducer at a reduced duty cycle relative to the full power mode, comparing the force data to a wakeup force threshold, and returning to the full power mode from the sleep mode when the force data is greater than the wakeup force threshold.