Memory Cache Power Management for Static Display Frames

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Solution Overview

Problem

Digital systems consume wasteful bandwidth and power when displaying static images for extended periods, as existing technologies do not efficiently manage memory cache and power usage during idle screen states.

Innovation Solution

A system with a memory controller and display controller that detects static images, allocates cache for frame buffer data in the memory cache to prevent power shutdown and reduce cache size during idle states, while enabling power management to conserve energy during dynamic image display.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the memory cache is allowed to shut down or reduce its effective size during idle screen states to save power, then power consumption is reduced, but frame buffer data cannot be retained and must be re-fetched from external memory when images change, increasing bandwidth usage and power consumption

Engineering Contradiction:
Improvepower consumptionVSAvoidbandwidth usage
Core Design Contradiction:
Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making the cache power management configuration changeable based on display state. The system dynamically switches between a first configuration (cache remains powered and full-sized during idle states with static images) and a second configuration (cache can shut down or reduce size during active states with dynamic images), optimizing power consumption for each operational context

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the power management configuration parameter of the memory cache based on whether the display is showing static or dynamic images. This parameter change allows the cache to maintain different operational states (powered on vs. powered off, full size vs. reduced size) to match the requirements of different display scenarios

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If the memory cache remains powered and full-sized during idle states to retain frame buffer data, then bandwidth usage is reduced by avoiding re-fetches, but power consumption increases unnecessarily during dynamic image display

Engineering Contradiction:
Improvebandwidth usageVSAvoidpower consumption
Core Design Contradiction:
Loss of energyVSUse of energy by moving object

Solution Approach 1:

The system dynamically adjusts the cache power management configuration based on the display state. During idle states with static images, the cache remains powered and full-sized to retain frame buffer data and avoid bandwidth waste. During active states with dynamic images, the configuration changes to allow cache shutdown or size reduction, reducing power consumption when data retention is less critical

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The power management configuration parameter is changed based on display activity detection. When static images are detected, the configuration favors data retention. When dynamic images are detected, the configuration shifts to power savings mode, changing the operational parameters of the cache to match current needs

Inventive Principle:
Principle #35Parameter changes

3Use of energy by moving object

If the cache size is reduced during dynamic image display to save power, then power consumption is reduced, but the cache may not have sufficient capacity to handle dynamic frame buffer updates

Engineering Contradiction:
Improvepower consumptionVSAvoidcache capacity
Core Design Contradiction:
Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The cache size is made dynamic through configuration changes. During idle states, the cache operates at full capacity to ensure sufficient capacity for frame buffer operations. During active states with dynamic images, the configuration allows size reduction for power savings, with the understanding that the system can transition back to full capacity when needed

Inventive Principle:
Principle #15Dynamics

4Reliability

If the system continuously fetches frame buffer data from external memory during static image display, then the latest data is always available, but power consumption and bandwidth usage increase unnecessarily

Engineering Contradiction:
Improvedata freshnessVSAvoidpower consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system performs preliminary action by retaining frame buffer data in the powered cache during idle states with static images. Instead of continuously fetching data, the data is fetched once and held in the cache, eliminating the need for continuous external memory access and reducing both power consumption and bandwidth usage while maintaining data availability

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3309674B1Memory power savings in idle display case
Publication Date: 2023.01.11 APPLE INC
  • EP3309674B1 patent drawingFigure 1
  • EP3309674B1 patent drawingFigure 2~3
  • EP3309674B1 patent drawingFigure 4

AI summary

In an embodiment, a system includes a memory controller that includes a memory cache and a display controller configured to control a display. The system may be configured to detect that the images being displayed are essentially static, and may be configured to cause the display controller to request allocation in the memory cache for source frame buffer data. In some embodiments, the system may also alter power management configuration in the memory cache to prevent the memory cache from shutting down or reducing its effective size during the idle screen case, so that the frame buffer data may remain cached. During times that the display is dynamically changing, the frame buffer data may not be cached in the memory cache and the power management configuration may permit the shutting down/size reduction in the memory cache.