Display Controller Synchronization for Touch and Force Sensing
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Solution Overview
Problem
Electronic devices face interference and noise issues when multiple functions, such as touch sensing and force sensing, operate concurrently on a shared display area, making it difficult to discern force sensing signals from the noise produced by the display.
Innovation Solution
A system where a controller synchronizes the operations of touch and force sensing devices with the display's pixel refresh time period, allowing force sensing operations to occur during periods of minimized noise and touch sensing operations to take place either during or outside this period, using technologies like capacitive, ultrasonic, or piezoelectric sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple functions (display, touch sensing, force sensing) operate concurrently on the display area, then the functionality and versatility of the device is improved, but signal interference and noise increase making it difficult to discern force sensing signals
Solution Approach 1:
The patent implements periodic action by synchronizing force sensing operations with the display refresh cycle. The force sensing device performs sensing operations during specific time periods when the display is refreshing pixels, creating periodic intervals when noise is minimized. This allows multiple functions to coexist by timing their operations to avoid simultaneous interference.
Solution Approach 2:
The patent applies preliminary action by having the display controller signal the force sensing device about upcoming noise periods before they occur. The controller provides advance information about when pixel refresh operations will happen, allowing the force sensing device to prepare and schedule its operations during low-noise intervals, preventing interference before it occurs.
2Measurement precision
If force sensing operations are performed during pixel refresh time period, then the signal-to-noise ratio is improved, but the timing coordination between display refresh and sensing operations becomes more complex
Solution Approach 1:
The patent implements feedback by having the display controller continuously signal the force sensing device about the current refresh state and upcoming noise periods. This feedback mechanism allows the sensing device to dynamically adjust its operation timing based on real-time display state information, maintaining optimal signal-to-noise ratio while managing timing coordination complexity through systematic information exchange.
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 approach reduces signal interference, enabling accurate force and touch sensing by minimizing noise overlap and improving the signal-to-noise ratio during sensing operations.
Implementation Method 1
the force sensing device can use capacitive sensing technology to detect force. One or more excitation signals can be received by the force sensing device during the pixel refresh time period, and one or more force sense signals can be received from the force sensing device when noise is minimized or reduced during the pixel refresh time period
Implementation Method 2
The touch sensing device can also use capacitive sensing technology to detect touch in some embodiments. One or more excitation signals can be received by the touch sensing device during the second time period, and one or more touch sense signals can be received from the touch sensing device during the second time period
Implementation Method 3
Other embodiments can use a different sensing technology to detect force, such as ultrasound or piezoelectric technology
Data Source
AI summary
A system can include a display, a first device, and a second device all operatively connected to a controller. The first and second devices each use or share at least a portion of the display area. The controller is adapted to transmit during a pixel refresh time period of the display a first signal that is received by the first device. The first sync signal indicates a first time period in which a first operation can be performed in the first device. The controller is also adapted to transmit a second sync signal that is received by the second device indicating a second time period in which a second operation can be performed in the second device. The second time period can be during the pixel refresh time period or outside of the pixel refresh time period.