Force Sensor Signal Processing for Multi-Object Input Detection
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Solution Overview
Problem
Existing input devices, such as touchpads and touch screens, face challenges in accurately determining which input object is applying a force to the surface and which is merely touching it, especially when multiple objects are present, due to complexities in signal processing and surface interactions.
Innovation Solution
A processing system that utilizes sensor circuitry and processing circuitry to receive signals from force sensors, calculate aggregate force metrics, and determine distances to differentiate between input objects applying force and those merely touching the surface, allowing for precise identification of input forces and positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple input objects are detected on the surface, then the input device can recognize more user interactions, but it becomes difficult to accurately determine which object is applying force and which is merely touching
Solution Approach 1:
The patent divides the sensing surface into multiple discrete sensor regions, each capable of independently detecting touch and force characteristics. By segmenting the input surface into multiple force sensors, the system can analyze force distribution across different locations to determine which specific input object is applying force, even when multiple objects are present simultaneously.
Solution Approach 2:
The patent introduces a force dimension in addition to the traditional touch position detection. By measuring not just the location of input objects but also the magnitude and distribution of force across multiple sensor points, the system creates an additional measurement dimension that enables differentiation between touching and pressing actions for multiple objects.
2Reliability
If force sensors are used to detect input force, then the device can distinguish pressing actions, but the signal processing complexity increases when multiple objects are present
Solution Approach 1:
The patent introduces aggregate force metrics as an intermediary computational layer between the raw force sensor signals and the final input object identification. By calculating aggregated force values for different input objects based on multiple sensor readings, the system simplifies the complex multi-object signal processing into manageable metrics that can be directly compared to determine force application.
3Measurement precision
If the surface is divided into multiple regions for force calculation, then force distribution can be analyzed, but the calculation overhead increases
Solution Approach 1:
The patent calculates aggregate force metrics selectively for regions where input objects are detected, rather than computing force distributions for all possible regions uniformly. This partial action approach maintains precise force distribution analysis where needed while reducing unnecessary calculations in regions without input objects, thereby improving processing efficiency.
Data Source
AI summary
A processing system for an input device, including: sensor circuitry configured to receive resulting signals from a plurality of force sensors of the input device; and processing circuitry configured to: determine a first position of a first input object and a second position of a second input object on a surface of the input device; determine a plurality of force values based on the resulting signals; calculate a first aggregate force metric for a first region of the input region based on a first subset of the plurality of force values; determine that the first region has an input force based on a first comparison involving the first aggregate force metric; calculate a first distance between the first position and a first region and a second distance between the second position and the first region; and determine that the first input object is applying the input force in response to the first distance being smaller than the second distance.