Multifocal Display Bit Sequence Control for Color Artifacts

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Solution Overview

Problem

Multifocal display devices face challenges with low frame rates and color artifacts due to the limitations of existing methods in generating bit sequences for focal plane images, particularly during optical power transitions.

Innovation Solution

The solution involves generating first and second bit sequences by discarding specific bits from the original sequence to achieve higher frame rates and reduce intensity variations, with the controller adjusting the display element to minimize artifacts by normalizing color intensities and positioning less significant bits closer to the start or end of the sequence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a sequential binary pattern is used to control the display element for field sequential color operation, then color images can be produced, but the frame rate is limited and color artifacts occur during optical power transitions

Engineering Contradiction:
Improveframe rateVSAvoidcolor artifacts
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent segments the bit sequence into multiple groups (first group, second group, third group) with different bit significances. By selectively discarding bits from different groups depending on whether an optical power transition is detected, the system handles different temporal contexts differently, thereby reducing color artifacts during transitions while maintaining high frame rates during stable periods.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent dynamically adjusts the bit sequence generation based on detected optical power transitions. When a transition is detected, the system switches to a different bit discarding strategy (discarding from second group) compared to when no transition is detected (discarding from first group). This dynamic adaptation allows the system to optimize between artifact reduction and frame rate maintenance in real-time.

Inventive Principle:
Principle #15Dynamics

2Object-generated harmful factors

If the highest intensity illumination of a binary color pattern is followed by the lowest intensity illumination in another focal plane image, then color artifacts are generated, but maintaining constant intensity would reduce color information

Engineering Contradiction:
Improvecolor artifactsVSAvoidcolor information
Core Design Contradiction:
Object-generated harmful factorsVSLoss of information

Solution Approach 1:

The patent applies different quality treatments to different parts of the bit sequence based on their significance. Less significant bits (third group) are discarded during transitions to reduce artifacts, while more significant bits (first group) are preserved to maintain color information. This local differentiation in bit handling quality resolves the contradiction between artifact reduction and information preservation.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the parameter of bit significance weighting based on the temporal context (transition vs. stable period). During transitions, the system effectively changes which bit parameters are retained or discarded, allowing intensity variations to be minimized when necessary while preserving color information when possible.

Inventive Principle:
Principle #35Parameter changes

3Adaptability or versatility

If bit sequences are generated for each focal plane image, then multifocal display is achieved, but intensity variations during optical power transitions degrade image quality

Engineering Contradiction:
Improvemultifocal display capabilityVSAvoidimage quality
Core Design Contradiction:
Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent performs preliminary detection of optical power transitions before generating the bit sequences for display. By detecting transitions in advance (or at the appropriate timing), the system can pre-adjust which bits to discard in the subsequent bit sequence generation, preventing intensity variations before they occur and maintaining image quality throughout the multifocal display operation.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3949384B1Multifocal display device and method
Publication Date: 2023.10.25 HUAWEI TECH CO LTD
  • EP3949384B1 patent drawingFigure 1
  • EP3949384B1 patent drawingFigure 2A~2B
  • EP3949384B1 patent drawingFigure 3A~3B

AI summary

The present invention provides a device, in particular a multifocal display device. The device comprising a display element configured to generate an image; and a controller configured to control the display element according to at least a first bit sequence provided over a first determined time period and a second bit sequence provided over a second determined time period, in order to generate the image with one or more colors, the bit sequences including for each color a number of bits of different significance. Moreover, the device is configured to generate the first bit sequence from an original bit sequence based on discarding at least one bit of a color and to generate the second bit sequence from the original bit sequence based on discarding at least one other bit of the color.