Stacked Haptic Actuator Assembly for Mobile Devices
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Solution Overview
Problem
Conventional mobile devices face challenges in producing distinct local and global haptic vibrations due to the use of a single actuator, leading to lag in local haptic responses and space constraints that prevent separate actuators for each type of vibration.
Innovation Solution
A mobile device design featuring a stacked actuator assembly with a rigidly coupled first actuator for global vibrations and a second actuator for local vibrations, separated by a compliant layer to decouple vibrations and allow independent activation, enabling separate tuning and optimization of each type of haptic response.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single actuator is used to produce both global and local haptic vibrations, then device complexity is reduced, but local haptic response speed deteriorates due to lag when rapidly accelerating and deaccelerating a vibrating mass
Solution Approach 1:
The patent divides the haptic actuation system into two separate actuators: a first actuator (e.g., linear resonant actuator) for global haptic vibrations and a second actuator (e.g., piezoelectric actuator) for local haptic vibrations. This segmentation allows each actuator to be optimized for its specific function, with the second actuator capable of rapid acceleration and deacceleration for crisp local haptic responses without being constrained by the mass and inertia of the first actuator.
Solution Approach 2:
The patent introduces a compliant layer positioned between the first and second actuators. This compliant layer mechanically couples the two actuators while having sufficiently low compliance in the direction parallel to the vibration plane of the first actuator to decouple vibrations. The intermediary layer allows the second actuator to apply force to the display panel out of the plane without transmitting vibrations from the first actuator, enabling independent operation and rapid response for local haptic feedback.
2Speed
If separate actuators are used for global and local haptic vibrations, then local haptic response speed is improved, but device complexity increases and space constraints are violated
Solution Approach 1:
The patent merges the first and second actuators into a single stacked actuator assembly where the actuators are positioned one above the other and share a common footprint. The first actuator is rigidly coupled to the back panel and the second actuator is rigidly coupled to the display panel, with the compliant layer between them. This merging allows both actuators to occupy the same spatial envelope, fitting within the thickness of the mobile device without requiring additional lateral space, while maintaining independent control for improved local haptic response.
Solution Approach 2:
The patent transitions from a lateral arrangement of actuators to a stacked configuration in the thickness dimension. By positioning the first and second actuators in different layers (one above the other) rather than side-by-side, the design accommodates both actuators within the limited footprint of the mobile device chassis. The compliant layer enables mechanical coupling in the thickness direction while maintaining vibration decoupling in the plane direction, allowing independent activation and optimized performance for both global and local haptic vibrations.
3Reliability
If separate actuators are used for global and local haptic vibrations, then haptic performance is optimized, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple actuators and the compliant layer into an integrated stacked actuator assembly that functions as a single manufacturable unit. The first and second actuators are positioned in a stacked configuration with a common footprint, allowing them to be assembled and aligned more easily than separate lateral placements. This integrated assembly can be installed as one component within the mobile device chassis, reducing the number of separate assembly steps and simplifying manufacturing despite the presence of multiple actuators.
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 allows for efficient generation of both local and global haptic vibrations within a single actuator assembly, optimizing each type of response and improving the device's ability to produce crisp and instantaneous local vibrations and strong global vibrations, while also simplifying integration and manufacturing.
Implementation Method 1
having a compliance in a direction parallel to a plane of vibration of the first actuator sufficiently low to decouple vibrations of the first actuator from the second actuator
Implementation Method 2
configured to vibrate in a plane of the back panel
Implementation Method 3
configured to apply a force to the display panel out of a plane of the display panel
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
A mobile device includes a chassis including a back panel and sidewalls. The device also includes a display panel connected to the chassis opposite the back panel. The device further includes an actuator assembly including a first actuator and a second actuator stacked on the first actuator, the first actuator being rigidly coupled to the back panel and being configured to vibrate in a plane of the back panel, and the second actuator being rigidly coupled to the display panel and configured to apply a force to the display panel out of a plane of the display panel. The device also includes an electronic control module in communication with the actuator assembly, the electronic control module being programmed to independently activate the first actuator and second actuator to generate a haptic vibration in the chassis and a haptic vibration in the display panel, respectively.