Piezo Actuator Drop Protection via Reverse Bending
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Solution Overview
Problem
Portable electronic devices, such as smartphones and PDAs, face challenges in providing effective tactile feedback and protecting their components, especially the piezo disk actuators, from damage due to drops and impacts, which can lead to mechanical failure and user input errors.
Innovation Solution
Incorporating a piezo disk actuator between the touch-sensitive input assembly and the base of the device, connected to a microprocessor and accelerometer, which applies a negative voltage to reverse bend the actuator upon detection of a fall, limiting movement and force exerted on the actuator, and providing tactile feedback simulating a dome-type switch for user confirmation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a piezo disk actuator is used to provide tactile feedback in a thin portable device, then the device can provide positive feedback and maintain a thin profile, but the actuator is vulnerable to damage from drops and impacts
Solution Approach 1:
The patent applies beforehand cushioning by using a polymer layer positioned between the touch-sensitive input assembly and the piezo disk actuator. This polymer layer acts as a cushion that absorbs impact forces before they reach the actuator, protecting it from damage during drops or impacts while allowing the actuator to function normally during regular operation.
Solution Approach 2:
The patent implements preliminary action by detecting a drop event through an accelerometer before significant damage can occur to the actuator. Upon detecting the drop, the system preemptively disables the piezo disk actuator, preventing potential damage from subsequent impacts or operations that would occur if the actuator remained active.
2Volume of moving object
If the device is made smaller for portability, then it becomes more portable and easier to carry, but space for user input devices is limited
Solution Approach 1:
The patent merges the display function and input function into a single integrated touch-sensitive display assembly. The touch-sensitive input assembly is disposed over the display, allowing the same surface to serve both as visual output and as an input interface, thereby eliminating the need for separate physical buttons or input devices and enabling the device to maintain a compact form factor.
Solution Approach 2:
The patent replaces traditional mechanical input devices (such as physical buttons or switches) with a touch-sensitive input assembly that provides tactile feedback through a piezo disk actuator. This substitution allows for a more compact design since no mechanical movement or additional space for physical components is required, while still providing tactile feedback to confirm user input.
3Speed
If the piezo disk actuator is positioned close to the touch-sensitive input assembly for efficient feedback, then tactile response is improved, but the actuator is more exposed to impact forces
Solution Approach 1:
The patent introduces a polymer layer as an intermediary between the touch-sensitive input assembly and the piezo disk actuator. This intermediary layer is positioned adjacent to the actuator and serves to absorb and distribute impact forces, reducing the stress transmitted to the actuator during drops or impacts while allowing the actuator to remain positioned close to the input assembly for efficient tactile feedback.
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 solution effectively protects the piezo disk actuators from impact-induced stress and enhances user experience by providing reliable tactile feedback, reducing the risk of mechanical failure and input errors while maintaining a thin device profile.
Implementation Method 1
An actuating arrangement including a piezoelectric actuator is disposed between the touch-sensitive input assembly and the base for selectively receiving an applied voltage to thereby apply a force to the touch-sensitive input assembly
Implementation Method 2
An accelerometer and functional components are housed within the housing
Data Source
AI summary
A portable electronic device includes a housing with a base. A touch-sensitive input assembly is spaced from and moveable relative to the base and a stopping arrangement limits movement of the touch-sensitive input assembly in the direction of the base. An actuating arrangement including a piezoelectric actuator for selectively receiving an applied voltage to thereby apply a force to the touch-sensitive input assembly. An accelerometer and functional components are housed within the housing. The functional components include a memory and a processor operably connected to the memory, the touch-sensitive input assembly, the piezoelectric actuator, and the accelerometer to monitor signals from the accelerometer and, if a fall is detected, apply a negative voltage to the piezoelectric actuator causing reverse bending of the piezoelectric actuator to permit the stopping arrangement to limit movement of the touch-sensitive input assembly and thereby limit force exerted on the piezoelectric actuator.