Liquid Crystal on Silicon Spatial Light Modulator with Embedded Pixel Circuitry

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Solution Overview

Problem

Existing holographic projectors face limitations in image quality due to constraints on pixel size and data streaming, which can result in artefacts and reduced resolution, especially when tiling schemes are not optimized for liquid crystal on silicon spatial light modulators.

Innovation Solution

A liquid crystal on silicon spatial light modulator with embedded pixel mapping circuitry that combines hologram pixels with light processing functions, such as lens and grating functions, within the silicon backplane, allowing for efficient tiling and reduced data streaming, thereby increasing update rates and improving image quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If tiling schemes are used to display holograms on liquid crystal on silicon spatial light modulators, then the hologram can be displayed on the available pixels, but pixel size constraints and data streaming limitations result in artefacts and reduced resolution

Engineering Contradiction:
Improvehologram display precisionVSAvoidpixel size constraints
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent divides the hologram into multiple tiles that can be independently processed and displayed across the spatial light modulator pixels. This segmentation allows optimization of each tile's processing while working within pixel size constraints, reducing artefacts and improving overall hologram display precision without requiring larger individual pixels

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a temporal dimension by implementing frame buffering and sequential updating mechanisms. Instead of attempting to display the entire high-resolution hologram simultaneously across limited pixels, the system updates tiles sequentially over multiple frames, effectively trading temporal processing for spatial resolution and eliminating data streaming bottlenecks

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If data streaming is used to supply pixel values to the spatial light modulator, then the hologram can be displayed, but the data streaming rate limits the pixel update rate and reduces image quality

Engineering Contradiction:
Improvepixel update rateVSAvoidimage quality degradation
Core Design Contradiction:
ProductivityVSLoss of information

Solution Approach 1:

The patent implements frame buffering where pixel values for upcoming frames are pre-calculated and stored in memory before being streamed to the spatial light modulator. This preliminary preparation of data eliminates real-time calculation bottlenecks during the display refresh cycle, enabling higher pixel update rates without losing holographic image quality

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates intermediate representations of the hologram data in buffer memory that can be rapidly copied to the spatial light modulator without requiring complex real-time processing. These copied data structures are optimized for fast transfer, separating the computationally intensive hologram calculation from the time-critical display update operation

Inventive Principle:
Principle #26Copying

3Productivity

If the spatial light modulator uses standard pixel architecture without embedded processing, then the device is simpler to manufacture, but processing tasks must be performed externally increasing system complexity and reducing update rates

Engineering Contradiction:
Improveprocessing speedVSAvoidsilicon backplane complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges the processing functions with the display functions by embedding pixel circuitry directly in the silicon backplane of the spatial light modulator. This integration allows pixel values to be processed and updated in-place without requiring separate external processing stages, significantly increasing processing speed while the modular circuit design keeps the added complexity manageable

Inventive Principle:
Principle #5Merging (Combining)

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 enhances the rate at which pixels can be updated, reduces artefacts, and improves the overall quality of holographic projections by moving processing tasks to the silicon backplane and optimizing tiling schemes, leading to higher resolution and more complex image interlacing techniques.

Implementation Method 1

The spatial light modulator may be a liquid crystal device in which case each pixel is an individually-addressable liquid crystal cell having birefringence. Each pixel may modulate the amplitude and/or phase of light in accordance with a corresponding hologram pixel.

Methodology Applied
Scientific EffectBirefringence: Birefringence

Implementation Method 2

The light is diffracted by the spatial light modulator. The complex light pattern emanating from the display device interferes at a replay plane to form a holographic reconstruction corresponding to the target image.

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 3

The complex light pattern emanating from the display device interferes at a replay plane to form a holographic reconstruction corresponding to the target image.

Methodology Applied
Scientific EffectInterference: Interference

Data Source

PatentEP3650950B1A spatial light modulator for holographic projection
Publication Date: 2022.07.06 DUALITAS LTD
  • EP3650950B1 patent drawingFigure 1
  • EP3650950B1 patent drawingFigure 2A
  • EP3650950B1 patent drawingFigure 2B

AI summary

There is provided a spatial light modulator arranged to display a light modulation pattern comprising a hologram. The spatial light modulator comprises a liquid crystal on silicon spatial light modulator having a plurality of pixels. The hologram has a plurality of pixels. The spatial light modulator comprises a silicon backplane. Each pixel of the spatial light modulator comprises a light-modulating element and a respective pixel circuit. Each pixel circuit is embedded in the silicon backplane. Each pixel circuit is arranged to drive the corresponding light-modulating element. Each pixel circuit is further arranged to combine a received pixel value of the hologram with a corresponding pixel value of the light processing function such that the light modulation pattern further comprises the light processing function. The light processing function comprises a lens function and/or a grating function.