Accessory Connection Detection via Voltage Measurement

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Solution Overview

Problem

Existing electronic devices face challenges in detecting connection with accessories when the host device is powered down or has a dead battery, as they cannot communicate to indicate their presence, hindering authentication and power transfer.

Innovation Solution

An accessory device with detection circuitry and a current source outputs a current over a contact, measures voltage as a function of time, and determines connection based on threshold voltage criteria, allowing it to authenticate and provide power to the host device even when it has no power.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the host device is powered down or has a dead battery, then power consumption is reduced, but the ability to detect connection and communicate with accessory devices is lost

Engineering Contradiction:

Improvepower consumptionVSAvoidconnection detection capability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent introduces an intermediary detection mechanism using voltage measurement circuitry that can detect the presence of a host device through voltage changes on the data line, even when the host is powered off. This intermediary method allows connection detection without requiring the host to be actively powered or communicating.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the traditional communication-based detection method (which requires powered devices to exchange signals) with an electrical field-based detection method. By measuring voltage changes on the data line caused by the host device's capacitance or leakage current, the system can detect connection without mechanical or electronic communication from the host.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Speed

If the accessory device outputs power before confirming connection, then power transfer can be initiated faster, but safety and security are compromised

Engineering Contradiction:

Improvepower transfer initiation speedVSAvoidsafety and security risk

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The patent performs preliminary connection detection by measuring voltage on the data line before initiating power transfer. This preliminary action confirms that a host device is properly connected and authenticated, ensuring safety and security before the faster power transfer process begins.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from voltage measurements to control the power transfer process. The accessory device continuously monitors voltage levels on the data line and uses this feedback to determine when it is safe to initiate power output, ensuring that power is only transferred when a valid connection is confirmed.

Inventive Principle:

Principle #23Feedback

3Loss of information

If traditional connection detection methods are used, then communication between devices can be established, but they fail when the host device has no power to communicate

Engineering Contradiction:

Improveconnection status informationVSAvoidoperation under power-off conditions

Core Design Contradiction:

Loss of informationVSAdaptability or versatility

Solution Approach 1:

The accessory device performs self-service connection detection by actively measuring voltage on the data line without requiring the host device to provide any signals or power. The host device's mere presence creates a detectable electrical effect that the accessory can measure and interpret as connection status.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent changes the detection parameter from communication-based signals (which require power) to voltage-based electrical characteristics (which can be measured without host power). By measuring voltage changes, leakage current, or capacitance effects on the data line, the system can detect connection status under all power conditions.

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

Enables successful authentication and power transfer between devices, ensuring safe and secure connections, even when the host device is powered off or has a dead battery, by detecting connection through voltage measurement and managing power delivery accordingly.

Implementation Method 1

measuring a voltage as function of time at the contact and determining whether the measured voltage at the contact reaches or exceeds a threshold voltage

Methodology Applied

Scientific EffectVoltage measurement: Ohm's Law

Data Source

PatentUS8898348B2Method and system for detecting connection of a host device to an accessory device

Publication Date: 2014.11.25 APPLE INC

AI summary

Techniques for detecting connection of a host device by an accessory device are provided. The accessory device outputs a pulsed voltage/current on its power contact and measure the voltage at the power contact in response to the pulsed voltage/current. If the measured voltage reaches a certain value at or after the expiration of a predetermined time, then the accessory concludes that a host device is connected to it.