Display Driver IC Self-Clock Time Offset Compensation
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Solution Overview
Problem
Mobile devices with display drivers face challenges in reducing power consumption while accurately displaying time, especially when operating in self-clock display modes, due to errors in internal clock signals and the need for continuous interfacing with application processors.
Innovation Solution
Incorporating a display driver integrated circuit (DDI) that generates internal synchronization signals and calculates time offsets to display time independently, reducing the need for continuous interfacing with application processors by using an oscillator, timer logic circuit, and symbol memory to adjust and display time in self-clock display mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the display device uses an internal clock signal for time display, then the device can operate independently without continuous interfacing with the application processor, but time accuracy deteriorates due to clock errors
Solution Approach 1:
The display device is configured to independently calculate and display time using its own internal clock signal without requiring continuous intervention from the application processor. The display driver integrated circuit generates display data based on the internal clock, enabling the display device to serve itself for time display operations, thereby reducing power consumption while maintaining operational independence.
Solution Approach 2:
The system implements a time offset compensation mechanism where the application processor calculates the difference between its accurate time and the display device's internal time, then provides this time offset to the display driver integrated circuit. The display device uses this feedback to adjust its displayed time, ensuring accuracy is maintained despite using the less accurate internal clock for independent operation.
2Measurement precision
If the display device interfaces continuously with the application processor, then time accuracy is maintained, but power consumption increases
Solution Approach 1:
Instead of continuous interfacing, the system uses periodic communication where the application processor sends time offset information to the display driver integrated circuit at intervals. This periodic action maintains time accuracy by regularly updating the display device with accurate time references while minimizing the frequency of communication events, thereby reducing overall power consumption compared to continuous interfacing.
3Device complexity
If the DDI calculates time independently using internal clock, then interfacing complexity with application processor is reduced, but time synchronization deteriorates
Solution Approach 1:
The system maintains time synchronization through a feedback mechanism where the application processor monitors the time difference between its accurate time and the display device's internal time, calculates the time offset, and sends this offset to the display driver integrated circuit. This feedback loop ensures that even though the display device operates independently with its own internal clock, it remains synchronized with the accurate time reference from the application processor.
Data Source
AI summary
A mobile device includes a display driver integrated circuit (DDI), a display panel, and an application processor. The DDI provides an internal synchronization signal based on an internal clock signal as a synchronization signal. The application processor calculates a time offset corresponding to a difference between a real time and the internal synchronization signal, and provides the time offset to the DDI. The DDI calculates a time to be displayed based on the time offset and a current time provided from the application processor, and displays the time to be displayed in the display panel in a self clock display mode.