Piezo Sound Output Lamp Control for Over-Current Protection

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Solution Overview

Problem

Existing automotive lamps lack the capability to output audio signals synchronously with video signals, requiring separate voice output devices that can cause issues like water ingress and increased workload, and piezos with high capacitance and low impedance face challenges with over-current and impedance changes due to temperature.

Innovation Solution

A sound output lamp control apparatus using a piezo with a stacked structure, including an audio driver, over-current prevention, and a control device that adapts audio signal output based on capacitance and impedance changes, diagnoses open loads, and prevents over-currents using resistors or low-pass filters.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a separate voice output device is installed in the lamp housing, then audio output capability is improved, but device complexity and risk of water ingress increase

Engineering Contradiction:

Improveaudio output capabilityVSAvoiddevice complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines the audio output function with the existing lamp structure by integrating a piezoelectric element directly into the lamp housing. This merging eliminates the need for separate voice output devices and their associated mounting holes, thereby reducing device complexity while maintaining audio output capability. The piezoelectric element utilizes the lamp housing itself as the output surface, creating a unified structure that performs both lighting and audio functions.

Inventive Principle:

Principle #5Merging (Combining)

2Power

If a piezo with high capacitance and low impedance is used, then audio output performance is improved, but over-current occurs

Engineering Contradiction:

Improveaudio output performanceVSAvoidover-current

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The patent introduces an impedance matching circuit as an intermediary between the audio amplifier and the piezoelectric element. This circuit acts as a mediator that transforms the low impedance of the piezo into a higher impedance level that is compatible with standard audio amplifiers, thereby preventing over-current conditions while maintaining the high power output performance that the piezo is capable of delivering.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If impedance matching is not performed, then device complexity is reduced, but audio output performance deteriorates

Engineering Contradiction:

Improvedevice complexityVSAvoidaudio output performance

Core Design Contradiction:

Device complexityVSPower

Solution Approach 1:

The patent applies impedance matching techniques that transform the electrical parameters of the piezoelectric element to be compatible with standard audio amplifiers. By changing the effective impedance level through circuit transformation rather than physically modifying the piezo itself, the system achieves optimal power transfer and audio output performance while keeping the overall device complexity manageable through the use of standard amplifier components.

Inventive Principle:

Principle #35Parameter changes

4Power

If piezo is driven at high power, then audio output performance is improved, but reliability decreases due to temperature changes affecting capacitance and impedance

Engineering Contradiction:

Improveaudio output performanceVSAvoidreliability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The patent implements a feedback mechanism that monitors the electrical characteristics of the piezoelectric element and adjusts the drive signal accordingly. By continuously measuring the capacitance and impedance changes that occur with temperature variations and using this information to adapt the driving parameters, the system maintains reliable operation across varying temperature conditions while preserving high power audio output performance.

Inventive Principle:

Principle #23Feedback

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 reliable audio output from automotive lamps by preventing over-currents and adapting to impedance and temperature changes, ensuring safe and efficient operation of piezos with high capacitance and low impedance.

Implementation Method 1

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

an over-current prevention device placed between the audio driver and the piezo and preventing an over-current of the piezo in a high-frequency domain of a predetermined first frequency or higher

Methodology Applied

Scientific EffectLow-pass filtering: Filter (electronic)

Data Source

PatentUS20260067617A1Method for controlling sound output lamp using piezo and apparatus thereof

Publication Date: 2026.03.05 HYUNDAI MOBIS CO LTD

AI summary

An apparatus for controlling a sound output lamp includes a piezo having a stacked structure and outputting a sound by vibrating an outer lens of the sound output lamp or a surface of a housing; an audio driver generating power for driving audio of the piezo, an over-current prevention device placed between the audio driver and the piezo and preventing, at the piezo, an over-current of a predetermined first frequency or higher in a high-frequency domain; and a control device providing the audio driver with an audio signal for controlling an audio output of the piezo.