Adaptive VCOM Control for Low Power Display Modes
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Solution Overview
Problem
Existing touch sensing devices face challenges in efficiently managing power consumption, particularly in transitioning between normal and low-power operating modes, which affects the accuracy and reliability of input detection and display quality.
Innovation Solution
A processing system that includes reference voltage generators for grayscale mode and VCOM control circuits to adjust VCOM voltage based on supply rails, allowing for separate calibration values for normal and low-power modes, and shutting down reference voltage generators to conserve power while maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If reference voltage generators are shut down to save power in low-power mode, then power consumption is reduced, but display quality and input detection accuracy may deteriorate
Solution Approach 1:
The system changes the VCOM voltage parameter specifically for low-power mode. The VCOM control circuit adjusts the VCOM voltage to a second calibrated value when reference voltage generators are shut down, ensuring that input detection accuracy is maintained despite the power-saving mode activation.
Solution Approach 2:
The system dynamically switches between different VCOM voltage values based on the operating mode. A mode indicator signal triggers the VCOM control circuit to select between a first calibrated VCOM voltage for grayscale mode and a second calibrated VCOM voltage for low-power binary mode, allowing adaptive optimization of both power consumption and detection accuracy.
2Use of energy by moving object
If reference voltage generators are shut down to save power in low-power mode, then power consumption is reduced, but display quality may deteriorate
Solution Approach 1:
The system changes the VCOM voltage parameter specifically for low-power mode. The VCOM control circuit adjusts the VCOM voltage to a second calibrated value when reference voltage generators are shut down, ensuring that display quality is maintained despite the power-saving mode activation.
Solution Approach 2:
The system dynamically switches between different VCOM voltage values based on the operating mode. A mode indicator signal triggers the VCOM control circuit to select between a first calibrated VCOM voltage for grayscale mode and a second calibrated VCOM voltage for low-power binary mode, allowing adaptive optimization of both power consumption and display quality.
3Device complexity
If a single VCOM voltage is used for both grayscale and low-power modes, then device complexity is reduced, but image flicker and sticking issues occur in low-power mode
Solution Approach 1:
The system segments the VCOM voltage control into mode-specific calibrated values. Instead of using a single VCOM voltage for all modes, the system provides a first calibrated VCOM voltage for grayscale mode and a second calibrated VCOM voltage for low-power binary mode, eliminating image flicker and sticking issues while maintaining manageable complexity through automated mode-based selection.
Data Source
AI summary
Embodiments described herein include a display device having a capacitive sensing device, a processing system and a method for providing an adaptive low-power mode. In one embodiment, the method includes generating a reference voltage with one or more reference voltage generators while a display device is in a grayscale mode. The method also includes driving subpixels in the grayscale mode with the reference voltage. The method further includes shutting down the one or more reference voltage generators and driving subpixels in a low power, binary mode with a VCOM voltage based on positive and negative supply rails.