Touch Surface Force Detection Using Haptic Actuation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing user input devices, such as trackpads, require additional force-measuring components like capacitive force sensors and strain gauges, which occupy valuable packaging space, impose design constraints, and increase manufacturing costs.
Innovation Solution
Utilize a haptic actuator and integrated accelerometer to measure touch surface accelerations, eliminating the need for additional force-measuring components by determining touch force through actuation and acceleration measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional force-measuring components (capacitive force sensors, strain gauges) are included in the user input device, then force determination capability is improved, but packaging space is reduced and manufacturing costs increase
Solution Approach 1:
The haptic actuator is made to serve dual purposes: providing haptic feedback to the user and measuring touch force through acceleration measurement. By driving the actuator with a known force detection driving signal and measuring the resulting acceleration with the accelerometer, the system determines touch force without requiring dedicated force-sensing components, thus eliminating the need for additional packaging space.
Solution Approach 2:
The patent combines the haptic actuator and accelerometer into an integrated force measurement system. The accelerometer, already present for other purposes, is combined with the haptic actuator to create a force sensing mechanism. This merging eliminates the need for separate force-measuring components, thereby preserving packaging space while maintaining force determination capability.
2Measurement precision
If additional force-measuring components (capacitive force sensors, strain gauges) are included in the user input device, then force determination capability is improved, but manufacturing costs increase
Solution Approach 1:
The haptic actuator is made to serve dual purposes: providing haptic feedback to the user and measuring touch force through acceleration measurement. By driving the actuator with a known force detection driving signal and measuring the resulting acceleration with the accelerometer, the system determines touch force without requiring dedicated force-sensing components, thereby reducing component count and manufacturing costs.
Solution Approach 2:
The patent recovers and repurposes the accelerometer (already present in the device for other functions) to serve as a force measurement sensor. Instead of discarding or underutilizing the accelerometer, the system leverages it to measure touch force by analyzing the acceleration response to a known driving signal, thereby eliminating the need for expensive dedicated force sensors.
3Device complexity
If the haptic actuator is driven with a force detection driving signal to measure acceleration, then touch force can be determined without additional components, but the actuator must be precisely controlled and calibrated
Solution Approach 1:
The system uses feedback from the accelerometer to measure the actual acceleration response of the haptic actuator to the applied touch force. By comparing the expected acceleration (from the known driving signal) with the measured acceleration, the system can accurately determine the touch force applied by the user, compensating for variations in actuator performance and calibration.
Solution Approach 2:
The force detection driving signal is applied periodically or in discrete pulses, allowing the system to measure acceleration responses at specific intervals. This periodic actuation enables accurate force measurement while minimizing continuous actuator operation, reducing heat generation and wear while maintaining measurement precision.
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
Increases packaging space and reduces manufacturing costs by eliminating the need for capacitive force sensors and strain gauges while enhancing force determination accuracy.
Implementation Method 1
drives the haptic actuator with a force detection driving signal to cause an acceleration in the touch surface
Implementation Method 2
Using a signal from the accelerometer, the acceleration is measured
Data Source
AI summary
Computing devices and methods for determining a force applied to a user input device are disclosed. In one example, a computing device comprises a user input device comprising a touch surface, a haptic actuator coupled to the touch surface, and an accelerometer coupled to the touch surface. The computing device receives a touch input from the touch surface and drives the haptic actuator with a force detection driving signal to cause an acceleration in the touch surface. The computing device measures the acceleration using a signal from the accelerometer and uses at least the acceleration to determine a force of the touch input on the touch surface.