Touch Sensor Controller Buffering for Low Power Response
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current mobile computing devices face a challenge in minimizing power consumption while maintaining fast response times, as reducing power consumption often conflicts with increasing responsiveness, particularly in touch-sensitive displays where lower refresh rates lead to slower response times and inefficiencies in processing input.
Innovation Solution
Implementing a low power mode with a touch sensor controller that increases scan rate upon detecting touch input, buffering subsequent touch data, and using a self-refreshing display panel with a frame buffer to asynchronously update the display at the fastest possible pixel rate, allowing for immediate rescan and buffering of updates during the refresh cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the display refresh rate is reduced to minimize power consumption, then power consumption is reduced, but response time increases and the system becomes less responsive to touch input
Solution Approach 1:
The system performs preliminary actions by buffering sensor input data and maintaining a ready-to-process state during low-power modes. The touch sensor controller continues to scan and buffer touch data even when the display is in a low refresh rate state, so that when a touch event occurs, the system can immediately process and display the buffered data without delay, thus maintaining fast response time while consuming less power during idle periods.
Solution Approach 2:
The system dynamically adjusts the display refresh rate based on activity state. During idle periods, the display operates at a lower refresh rate to save power. When touch input is detected, the system dynamically switches to a higher refresh rate to ensure fast response and smooth display updates. This dynamic adaptation allows the system to optimize power consumption during inactivity while maintaining responsiveness when needed.
2Use of energy by moving object
If the processor is placed in sleep state to reduce power consumption, then power consumption is reduced, but the system cannot quickly respond to sensor input
Solution Approach 1:
The touch sensor controller acts as an intermediary between the sensor and the processor. It continues to operate in a low-power state, scanning the touch sensor and buffering any detected touch data. When a touch event occurs, the controller generates an interrupt signal that wakes the processor from its sleep state. This intermediary approach allows the processor to remain in a low-power state while still being able to respond quickly to touch input through the interrupt mechanism.
Solution Approach 2:
The touch sensor controller performs self-service by autonomously scanning the touch sensor, detecting touch events, buffering the data, and generating interrupt signals without requiring the processor to be active. This allows the processor to remain in a deep sleep state, consuming minimal power, while the controller handles all preliminary detection and notification tasks, enabling fast response when the processor is awakened by an interrupt.
3Use of energy by moving object
If the touch sensor operates at low scan rate to conserve power, then power consumption is reduced, but touch input data may be lost during sleep state transitions
Solution Approach 1:
The touch sensor controller performs preliminary action by continuously scanning and buffering touch data even when operating at a low scan rate during power-saving modes. The buffer stores any touch events that occur during the transition to and from sleep states, ensuring that no data is lost. This preliminary buffering action guarantees data completeness while allowing the system to operate at low power consumption during idle periods.
4Device complexity
If display updates are synchronized to regular refresh periods to simplify processing, then system complexity is reduced, but display responsiveness is limited by the fixed refresh interval
Solution Approach 1:
The system dynamically adjusts display refresh behavior based on input events. Instead of being strictly synchronized to fixed refresh periods, the display can be updated immediately when touch input is detected, even if this means interrupting the regular refresh cycle. This dynamic approach allows the system to maintain simple processing logic while achieving fast display updates by breaking the synchronization constraint when responsiveness is needed.
Data Source
AI summary
A solution is proposed for processing input in a lower power user interface of touch-sensitive display panels. According to an embodiment, a mobile computing device is placed in the low power mode. During this mode, the sensor controller produces a raw event/interrupts on a detected touch. Upon detecting a touch, the sensor controller also automatically increases the scan rate of the touch sensor, while the triggered event or interrupt proceeds to wake the system into a higher power state. Subsequent touch data received while the system is booting into the higher power state is buffered by the timing controller, or by a bridge chipset, while the processor(s) in the power up. When awake, the processor(s) collect the touch samples from the buffer, and processes the touch samples, generating updated displays where necessary.