Mid-Air Haptic Interface Using Dual-Frequency Ultrasonic Transducers
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Solution Overview
Problem
Existing haptic interfaces using matrices of identical transducers find it difficult to generate complex and varied haptic effects, limiting their ability to create immersive experiences in virtual, augmented, and mixed reality applications.
Innovation Solution
A 'mid-air' haptic interface featuring a control circuit and multiple sets of ultrasonic transducers emitting at different carrier frequencies, allowing for the generation of acoustic pressures in distinct focal zones, enabling the creation of complex haptic effects by modulating signals and calculating phase shifts to concentrate ultrasonic waves in predefined areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If identical transducer arrays emitting at the same carrier frequency are used, then the device complexity is reduced and manufacturing is simplified, but the ability to generate varied and complex haptic effects deteriorates
Solution Approach 1:
The patent applies local quality by assigning different carrier frequencies to different spatial zones of the transducer array. Each zone (first zone with first carrier frequency, second zone with second carrier frequency) has distinct acoustic characteristics tailored to generate specific haptic effects at different locations, enabling varied haptic experiences while maintaining a unified device structure
Solution Approach 2:
The patent changes the carrier frequency parameter across different spatial zones of the transducer array. By varying this critical parameter from the first zone to the second zone, the system generates different acoustic pressures and haptic effects without changing the physical structure of the transducers themselves, thus maintaining manufacturing simplicity while achieving haptic diversity
2Adaptability or versatility
If transducers of different sizes and/or materials are used to generate varied haptic effects, then the haptic effect variety is improved, but the device complexity increases
Solution Approach 1:
The patent segments the transducer array into multiple spatial zones (first zone, second zone, etc.), each responsible for generating specific haptic effects through distinct carrier frequencies. This segmentation allows independent control of acoustic characteristics in different regions without requiring physically different transducers, reducing overall device complexity while maintaining haptic variety
Solution Approach 2:
The patent makes the transducer array universal by using identical transducers across all zones that can operate at multiple carrier frequencies through digital signal modulation. This multi-functional approach allows a single transducer type to serve multiple haptic functions by varying the drive frequency, eliminating the need for specialized transducers for different haptic effects and thus reducing device complexity
3Adaptability or versatility
If multiple sets of transducers emitting at different carrier frequencies are used, then the ability to generate haptic effects at different distances and extents is improved, but the device complexity increases
Solution Approach 1:
The patent applies dynamics by enabling the transducer array to dynamically switch between different carrier frequencies in different spatial zones based on real-time requirements. The control circuit can adaptively modulate signals to first carrier frequency in the first zone and second carrier frequency in the second zone as needed, providing flexible focal zone control without permanent complex hardware configuration
Solution Approach 2:
The patent introduces a control circuit as an intermediary between the simple transducer array and the complex haptic effect generation requirements. This control circuit processes digital signals and translates them into appropriate acoustic pressures by modulating carrier frequencies in different zones, thereby achieving focal zone flexibility without adding physical complexity to the transducer configuration itself
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 the generation of varied and complex haptic effects at different distances and extents, enhancing user immersion in VR, AR, and MR applications without the need for modulating transducer power, and allowing for precise control over tactile sensations.
Implementation Method 1
use a matrix of ultrasonic transducers excited at a frequency greater than 20 kHz, called the carrier frequency, to generate a plurality of ultrasonic waves which, not audible, are focused by playing on the phase shift of the carriers in a predefined area of space, to generate an acoustic pressure
Implementation Method 2
focused by playing on the phase shift of the carriers in a predefined area of space
Implementation Method 3
a plurality of identical micromachined piezoelectric transducers (PMUT) generating a haptic effect on the user's hand
Implementation Method 4
generate an acoustic pressure detectable tactilely in at least a first focal zone
Data Source
Figure 1~2
Figure 3
Figure 4~5A
AI summary
A mid-air haptic interface, comprising: - a control circuit (3), - a plurality of ultrasonic transducers (2) connected to said circuit, of which a first set (25) of transducers emitting at a first ultrasonic carrier frequency and at least a second set (26) of transducers emitting at a second ultrasonic carrier frequency different from the first; the control circuit being configured to modulate the signals (30) sent to the transducers (2) in order to: o generate with the ultrasonic waves emitted by at least a part of the transducers of the first set an acoustic pressure detectable by touch in at least a first focal zone (10), and o generate with the ultrasonic waves emitted by at least a part of the transducers of the second set an acoustic pressure detectable by touch in at least a second focal zone (11).