Foveated Display Pixel Bus Latching Without Multiplexers

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Solution Overview

Problem

Foveated display architectures using multiplexers consume significant die area and energy, reducing the field of view and increasing power consumption as the number of display pixels increases.

Innovation Solution

Implement a multiplexer-free architecture by hardwiring groups of source latches to pixel data bus wires and using time multiplexing for higher-resolution groupings, along with gating slices of the pixel data bus to reduce energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiplexers are used to route image data to source latches in foveated displays, then routing flexibility is improved, but die area consumption increases and field of view decreases

Engineering Contradiction:

Improverouting flexibilityVSAvoiddie area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent removes multiplexers from the data bus architecture entirely, extracting the problematic component that caused die area consumption. Instead of using multiplexers to route image data to source latches, the invention implements a direct routing scheme where data bits are assigned to specific bus wires based on their destination, eliminating the need for multiplexing hardware and thereby reducing die area while maintaining routing capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent transitions from a time-multiplexed routing approach (using multiplexers that switch connections over time) to a spatial routing approach (assigning specific data bits to specific bus wires). This dimensional change from temporal to spatial organization allows direct routing without multiplexers, resolving the contradiction between routing flexibility and die area consumption

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If multiplexers are used to route image data to source latches, then routing capability is improved, but energy consumption increases

Engineering Contradiction:

Improverouting capabilityVSAvoidenergy consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by stationary object

Solution Approach 1:

The patent extracts and removes the multiplexer components from the system, eliminating the source of energy consumption associated with multiplexer operation. By replacing the multiplexer-based routing system with a direct routing architecture, the patent eliminates the dynamic switching operations that consume significant energy, thereby reducing overall energy consumption while preserving routing capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent implements continuous data flow through the display pipeline by eliminating the stop-start nature of multiplexer switching. Data flows continuously through dedicated bus wires to source latches without being interrupted by multiplexer switching cycles, maintaining continuous useful action and reducing energy consumption associated with repeated switching operations

Inventive Principle:

Principle #20Continuity of useful action

3Reliability

If image data is sent across the pixel data bus to source latches, then data delivery is achieved, but energy consumption increases with the number of columns

Engineering Contradiction:

Improvedata deliveryVSAvoidpixel data bus energy

Core Design Contradiction:

ReliabilityVSUse of energy by stationary object

Solution Approach 1:

The patent segments the pixel data bus into column-specific segments, where each bus wire is dedicated to carrying data for specific column ranges. This segmentation allows the system to activate only the necessary bus segments for current operations, reducing energy consumption proportional to the number of active columns while maintaining reliable data delivery to the required source latches

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements local quality by assigning specific data bits to specific bus wires based on their destination columns. This localized routing ensures that energy is consumed only in the specific regions of the data bus that are currently active, rather than energizing the entire bus, thereby reducing overall energy consumption while maintaining data delivery reliability

Inventive Principle:

Principle #3Local quality

Data Source

PatentUS12462729B2Mux-free architecture for pixel data bus latching in foveated displays

Publication Date: 2025.11.04 APPLE INC

AI summary

On a foveated electronic display, foveated image data may include a variety of groupings of pixels in different resolutions for different parts of the display. As such, different parts of the foveated image data are routed to different pixels of the electronic display. One way of routing data is to use multiplexers to select which image data is routed to which source latches of columns of pixels of the electronic display. Depending on the number of columns of the electronic display, however, the multiplexers may consume a significant portion of the die area while also consuming a significant amount of energy and reducing the field-of-view (FOV). Instead of using multiplexers to route foveated image data in the electronic display, groups of source latches of the electronic display may be hardwired to respective wires of a pixel data bus.