Touch Sensitive Device Haptic Simulation via Complex Modulation
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Solution Overview
Problem
Existing touch-sensitive devices struggle to effectively simulate tactile feedback at ultra-low frequencies, which are below the frequency range of the coupled system, limiting their ability to provide realistic haptic sensations such as a button click or other low-frequency stimuli.
Innovation Solution
A method involving the generation of a carrier wave signal modulated with complex modulation, where the modulated signal's time response matches the desired haptic sensation, allowing users to demodulate the higher frequency signal into a perceived low-frequency haptic response, utilizing a touch surface and force exciter to simulate sensations below the system's frequency bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a force exciter is used to generate tactile feedback at ultra-low frequencies, then the haptic sensation can be simulated, but the frequency must be below the system's frequency bandwidth which limits direct generation capability
Solution Approach 1:
The patent uses mechanical vibration at higher frequencies (within the system's bandwidth) and employs the acoustic radiation pressure effect to create a perceived low-frequency haptic sensation. The vibration signal is modulated such that the envelope corresponds to the desired low-frequency sensation, while the actual vibration occurs at a higher carrier frequency that the force exciter can generate.
Solution Approach 2:
The patent substitutes direct mechanical vibration at low frequencies with an acoustic field-based approach. Instead of directly generating mechanical vibration at ultra-low frequencies (which the system cannot do), it uses acoustic radiation pressure created by higher-frequency vibrations to produce the same perceptual effect, effectively replacing the mechanical generation mechanism.
2Measurement precision
If direct low frequency vibration is used to produce haptic sensation, then the sensation is accurate, but the system cannot generate frequencies below its bandwidth
Solution Approach 1:
The system generates mechanical vibration at a higher carrier frequency within its operational bandwidth, then modulates this vibration to create an envelope that corresponds to the desired low-frequency haptic sensation. The force exciter vibrates the touch surface at the higher frequency, but the modulated signal creates the perception of ultra-low frequencies through acoustic radiation pressure.
Solution Approach 2:
The patent changes the frequency parameter by operating at a higher carrier frequency than the desired sensation frequency, then uses modulation to transform the perceived frequency. The actual vibration frequency is changed from the target ultra-low frequency to a higher frequency that the system can generate, while the perception remains at the original lower frequency due to the modulation and acoustic radiation pressure effects.
3Adaptability or versatility
If complex modulation is applied to the carrier wave signal, then the desired haptic sensation can be simulated at ultra-low frequencies, but the signal processing becomes more complex
Solution Approach 1:
The patent applies periodic modulation to the carrier wave signal, creating a modulated signal where the envelope periodicity corresponds to the desired haptic sensation frequency. The carrier wave is modulated with a periodic function that creates the perception of ultra-low frequency vibration through acoustic radiation pressure, allowing the system to simulate haptic sensations across different frequency ranges using a single force exciter.
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 approach enables the simulation of desired haptic sensations at ultra-low frequencies, enhancing user experience by efficiently utilizing the available bandwidth and providing more realistic tactile feedback, such as a button click, through the use of complex modulation techniques.
Implementation Method 1
a piezoelectric element which form a switch to vibrate the element to apply a reaction force to a user's finger
Data Source
AI summary
A touch sensitive device comprising a touch surface, a force exciter coupled to the touch surface to excite vibration in the surface in response to a signal sent to the exciter, with the touch surface and exciter together forming a coupled system and a signal generator to generate the signal, with the signal generator generating a carrier wave signal at frequencies within the frequency bandwidth of the coupled system and modulating the carrier wave signal with a complex modulation where the modulated carrier wave signal has a time response comparable to that of a low frequency signal which produces a desired haptic sensation whereby a user touching the touch surface excited by the exciter in response to the modulated carrier wave signal experiences the desired haptic sensation which is perceived at a frequency below the frequency bandwidth of the coupled system.