Touchscreen Haptic Control Path for Near-Zero Latency Feedback
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Solution Overview
Problem
Conventional haptic feedback systems in touchscreens suffer from latency issues, where the delay between sensing a touch event and providing a haptic response can range from a few milliseconds to over 100 milliseconds due to the involvement of the system host controller, leading to annoying user experiences.
Innovation Solution
A haptic feedback system that bypasses the system host controller by directly transmitting a haptic trigger signal from a touch controller to an actuator controller via a dedicated or serial bus interface, allowing for immediate processing and actuation of haptic waveforms on haptic drive elements, reducing latency to less than 30 milliseconds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the system host controller is involved in processing touch events and generating haptic control signals, then system-level processing and control can be performed, but haptic feedback latency increases to several milliseconds or over 100 milliseconds
Solution Approach 1:
The system is segmented into two independent control paths: a fast path for haptic feedback that bypasses the system host controller, and a standard path for other processing that goes through the system host controller. The touch controller directly generates haptic control signals for immediate feedback, while maintaining the ability to send touch events to the system host controller for higher-level processing.
Solution Approach 2:
The touch controller acts as an intermediary that receives touch events from the touchscreen and can directly generate haptic control signals without waiting for system host controller processing. This intermediary role allows the system to maintain fast haptic response while still enabling comprehensive system-level processing through the standard path.
2Loss of time
If a dedicated signal path is used between touch controller and actuator controller, then haptic feedback latency is reduced to near-zero, but device complexity increases
Solution Approach 1:
The touch controller is designed with multi-functionality, serving both as a touch event processor and as a direct haptic control signal generator. This universal component can operate in two modes: sending touch events through the system host controller for standard processing, or directly generating haptic control signals for immediate feedback, thereby reducing latency without requiring separate dedicated hardware paths.
3Ease of manufacture
If haptic feedback is provided through conventional transducers vibrating the entire panel, then haptic feedback can be generated, but localization precision and user experience are degraded
Solution Approach 1:
The system implements local quality by providing haptic feedback at the specific location where the touch event occurred, rather than vibrating the entire panel. The touch controller identifies the touch position and generates localized haptic control signals that activate only the relevant region, improving localization precision while maintaining ease of manufacture through software-controlled actuation.
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 provides consistently timed and responsive haptic feedback, improving user experience by ensuring that haptic responses are felt within a short duration, typically less than 10 milliseconds, thus enhancing the tactile feedback in touchscreen interactions.
Implementation Method 1
A capacitive touchscreen panel is coated, partially coated, or patterned with a material that conducts a continuous electrical current across a sensor. The sensor exhibits a precisely controlled field of stored electrons in both the horizontal and vertical axes to achieve capacitance.
Implementation Method 2
Piezoelectric actuators are sometimes used as the transducers. The piezoelectric actuators vibrate when excited by an electrical signal.
Data Source
AI summary
A haptic feedback system includes a user interface device, such as a touchscreen that includes a touch panel and one or more haptic drive elements coupled to the touch panel, a touch controller, and an actuator controller. The touch controller receives sensed data from the touch panel, and in response generates and sends a haptic signal to an actuator controller. Generation and transmission of the haptic signal bypasses any system host controller. A dedicated signal path couples the touch controller and the actuator controller, over which the haptic signal is transmitted. Alternatively, the haptic signal is transmitted from the touch controller to the actuator controller over a serial bus interface. In response to the received haptic signal, the actuator controller implements an appropriate drive signal in the form of a haptic waveform to the one or more haptic drive elements of the touchscreen.