Piezoelectric Vibrating Device Resolving Haptic and Audio Thickness Trade-off
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Solution Overview
Problem
Existing vibrating devices with piezoelectric elements attached to glass surfaces, such as in smartphones, struggle to generate sufficient sound volume and transmit adequate vibration while maintaining a slim design, as they require additional thickness for effective sound production.
Innovation Solution
A vibrating device comprising a first transparent glass plate and a second transparent resin plate with a lower modulus of elasticity, where the piezoelectric element is placed in a storage part on the resin plate, allowing for efficient vibration transmission and audible sound generation without increasing the device's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If piezoelectric elements are attached to glass surfaces to achieve haptic function, then tactile sensation is provided, but sound generation capability is insufficient
Solution Approach 1:
The patent uses a composite structure combining glass plate and resin plate with different elastic moduli. The glass plate provides hardness and protection while the resin plate with lower elastic modulus enables sufficient vibration displacement for both haptic feedback and audible sound generation, resolving the contradiction between haptic reliability and sound volume.
Solution Approach 2:
The patent applies different material properties to different parts of the protective plate - the glass plate maintains high elastic modulus for durability while the resin plate portion has lower elastic modulus to enable vibration. This local differentiation allows the same structure to serve both haptic and audio functions effectively.
2Reliability
If piezoelectric elements are attached to the back of cover glass, then haptic function is achieved, but the installability in the thickness direction is limited
Solution Approach 1:
The patent transitions from attaching piezoelectric elements to the back surface of glass (2D attachment) to embedding them within a multi-layer resin structure (3D integration). This dimensional change allows the piezoelectric elements to be positioned optimally within the thickness direction while maintaining a slim overall profile.
Solution Approach 2:
The piezoelectric elements are nested within the resin plate structure, which itself is integrated with the glass plate. This nested arrangement allows efficient use of space in the thickness direction, enabling haptic function without increasing overall device thickness.
3Object-generated harmful factors
If the thickness of the protective plate is increased to improve sound generation, then audible sound can be generated, but the device becomes less slim and installability is reduced
Solution Approach 1:
The patent changes the elastic modulus parameter by introducing a resin plate with lower elastic modulus than glass. This material parameter change enables sufficient vibration displacement for sound generation without increasing thickness, as the softer resin material requires less thickness to achieve the same vibratory amplitude.
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 enables reliable haptic feedback and audible sound production with reduced thickness, enhancing installability and maintaining a slim, high-end feel by using a resin plate that supports the piezoelectric element, which is thinner than the glass plate, allowing for effective vibration and sound transmission.
Implementation Method 1
a piezoelectric element attached to glass or other material
Data Source
AI summary
In an embodiment, a surface of a smartphone 10 is covered with a transparent protective panel 22 supported by rims 16 of a housing 12, and a display device 18 and touch panel 20 are placed in a storage part 14 of the housing 12. The protective panel 22 is constituted by joining a glass plate 22A and resin plate 22B together, and concave parts 30A, 30B are provided on the joining surface side of the resin plate 22B, with piezoelectric vibrating elements 40 placed therein and joined to the glass plate 22A, wherein vibration is transmitted to the surface of the protective panel 22 as surface acoustic waves, demonstrating a haptic function, and also, audible vibration is generated because the modulus of elasticity of the resin plate 22B is lower than that of the glass plate 22A, achieving an operation as a speaker (or receiver).