Display Panel Sound Generation with Harmonic Cancellation
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Solution Overview
Problem
Display devices experience deterioration in sound quality due to harmonic tones having different frequencies from the fundamental tone, leading to reduced sound pressure levels and quality.
Innovation Solution
A display device with two sound generators, one using a piezoelectric element and the other a linear resonant actuator, where the phases and sound pressure levels of the harmonic tones are adjusted to create a third sound with amplified fundamental tone and reduced harmonic tone sound pressure levels, using a phase shifter and look-up table to modulate sound data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single sound generator is used to output sound, then the device structure is simple, but the sound quality deteriorates due to harmonic tones having different frequencies from the fundamental tone
Solution Approach 1:
The sound generation function is segmented into two independent sound generators: a first sound generator (piezoelectric element) that generates the fundamental tone, and a second sound generator (linear resonant actuator) that generates harmonic tones. This segmentation allows independent control of each sound generator to optimize the fundamental tone while suppressing unwanted harmonic tones, thereby improving sound quality without excessive structural complexity.
Solution Approach 2:
The invention changes the operational parameters of the second sound generator by adjusting the phase and amplitude of the drive signal. Specifically, the phase of the second sound generator is shifted relative to the first sound generator, and the amplitude is adjusted so that the harmonic tones from the second generator cancel out the unwanted harmonic tones from the first generator. This parameter adjustment resolves the contradiction by maintaining simple device structure while achieving high sound quality through precise parameter control.
2Power
If the sound pressure level of harmonic tones is increased to enhance overall sound output, then the fundamental tone quality deteriorates due to the presence of different-frequency harmonic tones
Solution Approach 1:
The invention converts the harmful effect of harmonic tones into a beneficial effect by using the second sound generator to produce harmonic tones that are phase-shifted and amplitude-adjusted to cancel the unwanted harmonic tones from the first sound generator. This approach transforms the previously harmful harmonic interference into a useful cancellation mechanism, allowing high sound pressure levels without compromising fundamental tone quality.
Solution Approach 2:
The second sound generator acts as a counterweight to the unwanted harmonic tones produced by the first sound generator. By generating harmonic tones with opposite phase and adjusted amplitude, the second generator creates a counterbalancing effect that neutralizes the harmful harmonic components while maintaining the overall sound pressure level, thus preserving fundamental tone quality.
3Reliability
If phase adjustment is applied to reduce harmonic tone interference, then the control complexity increases
Solution Approach 1:
The invention implements preliminary action by pre-calculating and storing the optimal phase shift values in a lookup table during the design phase. During operation, the system simply retrieves the appropriate phase shift value from the lookup table based on the operating conditions, rather than performing complex real-time phase calculations. This approach maintains high sound quality through precise phase control while minimizing control complexity during actual operation.
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 effectively prevents sound quality deterioration by increasing the sound pressure level of the fundamental tone and reducing harmonic tone levels, providing high-quality sound by optimizing the phase and amplitude relationships between the sounds.
Implementation Method 1
a first sound generator on a first surface of the display panel, the first sound generator configured to vibrate the display panel to output a first sound
Implementation Method 2
a second sound generator being configured to output a second sound
Implementation Method 3
the first sound generator configured to vibrate the display panel to output a first sound
Data Source
AI summary
A display device includes: a display panel; a first sound generator on a first surface of the display panel, the first sound generator being configured to vibrate the display panel to output a first sound; and a second sound generator configured to output a second sound. A third sound is a sum of the first sound and the second sound, and a sound pressure level of at least one of harmonic tones of the third sound is less than a sound pressure level of at least one of harmonic tones of the first sound.