Multifocal Display Lens Control for Flicker Reduction
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Solution Overview
Problem
Multifocal Display (MFD) devices face significant image quality issues due to oscillation artifacts caused by lens inertia in focus tunable lenses, leading to flicker and distortion, which existing preprocessing methods are insufficient to fully address.
Innovation Solution
A modified focal plane arrangement where the controller selectively tunes the focus of the lens to a plurality of focal planes using pre-defined groups with specific index differences and sequence rules, reducing extreme control signal changes and minimizing flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a focus tunable lens is used to rapidly switch focal planes in an MFD device, then the ability to create a multifocal 3D display is improved, but oscillation artifacts and flicker appear due to lens inertia
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal focal plane sequences in a lookup table before operation. The controller retrieves pre-optimized sequences that minimize abrupt focal transitions, thereby reducing oscillation artifacts and flicker while maintaining high-speed switching capability. This approach prepares the system in advance to avoid harmful oscillations during runtime.
Solution Approach 2:
The patent implements dynamics by adaptively adjusting the focal plane switching sequence based on real-time conditions. The controller dynamically selects from multiple pre-stored sequences, optimizing the transition path between focal planes to minimize lens inertia effects. This dynamic adaptation allows the system to maintain high switching speed while reducing oscillation artifacts through intelligent sequence selection.
2Speed
If current step control signals are applied to rapidly change focal planes, then the response speed is improved, but pronounced overshoot and ringing artifacts occur
Solution Approach 1:
The patent applies preliminary action by pre-calculating optimal current control waveforms and storing them associated with each focal plane transition. Instead of applying simple current steps that cause overshoot, the system retrieves pre-optimized waveforms that smoothly drive the lens to target focal planes, maintaining fast response while eliminating ringing artifacts and improving optical power precision.
Solution Approach 2:
The patent implements parameter changes by transforming the control approach from fixed current steps to variable current waveforms. The controller adjusts current magnitude and timing parameters dynamically based on pre-stored optimization data, enabling fast focal plane transitions without the pronounced overshoot and ringing that occur with simple step inputs.
3Adaptability or versatility
If multiple focal planes are switched during a frame period, then the multifocal display capability is improved, but flicker increases due to lens inertia oscillations
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing complete focal plane sequences that visit multiple focal planes within a frame period while minimizing oscillations. The controller retrieves these pre-optimized sequences, enabling the system to maintain stable images across multiple focal plane transitions and thereby improve multifocal display capability without increasing flicker.
Solution Approach 2:
The patent implements periodic action by organizing focal plane visits into regular, predictable sequences stored in advance. By following pre-determined periodic patterns rather than arbitrary switching, the system maintains image stability during multiple focal plane transitions within each frame period, reducing flicker while preserving multifocal display versatility.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces flicker and improves image quality by minimizing the impact of artifacts during transitions between focal planes, ensuring a more stable and flicker-free multifocal display experience.
Implementation Method 1
an electrically focus-tunable lens or a deformable membrane mirror device (DMMD) may be used as the focus tunable lens
Implementation Method 2
the focus tunable lens is able to change its focal distance, in order to selectively focus on one of a plurality of focal planes of different index
Data Source
AI summary
A multifocal display device has a focus tunable lens, a controller, and a storage. The controller selectively tunes the focus of the lens to a plurality of focal planes of different index during a frame per A focal plane of lower index has a shorter focal distance. The storage stores a plurality of focal plane groups, each group including the plurality of focal planes in a different sequence. The controller selects a first group and tunes, during a first frame period, the focus of the lens to each one of the focal planes in the first group according to their sequence, and selects a second group from groups allowed by a selection rule, and tunes, during a second frame period, the focus of the lens to each one of the focal planes in the second group according to their sequence.