Low Power Display Controller for Reduced Mode Visual Indication
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Solution Overview
Problem
Portable electronic devices in reduced power mode lack visual indication of their operational state, such as time or battery status, due to deactivated display controllers, which can leave users unaware of the device's status and functionality.
Innovation Solution
A display controller with a processor interface, memory, and display processor that stores and displays a predetermined image, such as a digital clock or battery meter, even in reduced power mode, using minimal resources and updating the image periodically to prevent burn-in and conserve memory.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the display controller is deactivated in reduced power mode, then battery power is conserved, but the user receives no visual indication of the device's operational state
Solution Approach 1:
The display controller is segmented into two operational paths: a full power mode path for normal operation and a reduced power mode path for low-power operation. The reduced power mode path includes a minimal display processor that can independently render simple graphics without requiring the full display controller functionality, enabling selective activation of only the necessary components during reduced power mode.
Solution Approach 2:
The display controller includes an integrated minimal display processor capable of independently generating and rendering simple graphics without requiring data from the device processor. This self-service capability allows the display controller to autonomously provide visual feedback during reduced power mode, eliminating the need for external data input while maintaining user awareness of device state.
2Loss of information
If the display controller remains active to provide visual information, then the user is informed of the device status, but battery power is consumed
Solution Approach 1:
Instead of activating the full display controller functionality, only a minimal subset is activated during reduced power mode. The minimal display processor renders only essential information (such as basic graphical indicators) rather than complete application graphics, providing sufficient visual feedback while consuming significantly less power than full operation.
Solution Approach 2:
The display controller dynamically changes its operational parameters based on power mode. During reduced power mode, it switches to a low-complexity rendering mode with reduced processing requirements, adjusted clock frequencies, and modified data throughput, thereby reducing power consumption while maintaining essential display functionality.
3Use of energy by moving object
If simple predetermined images are displayed in reduced power mode, then power is conserved and visual indication is provided, but the display may suffer from burn-in
Solution Approach 1:
The minimal display processor periodically updates the displayed image during reduced power mode rather than holding a static image. This periodic refresh prevents phosphor burn-in by periodically redistributing electron beam exposure across the display phosphors, while still maintaining the low-power benefit of displaying simple predetermined images.
Data Source
AI summary
A display controller for use within an electronic device includes a dedicated memory and a low power display processor for displaying information when the electronic device is operating in a reduced power mode of operation (e.g., sleep mode). The memory stores display data for a predetermined image and the display processor supplies the display data to a display panel of the electronic device when the electronic device is operating in the reduced power mode. The display controller may also include a processor interface for receiving control information from the electronic device's device processor to enable the display processor to determine that the electronic device is operating in reduced power mode. The display processor may be configured to scale the stored display data when, due to memory size constraints, the memory stores the display data at a resolution that is different from (e.g., less than) the display panel resolution.