Beam Steering Backlight Unit for Holographic Displays
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Solution Overview
Problem
Current 3D image display methods, such as glasses-type and non-glasses-type methods, face limitations in providing consistent depth perception and cause viewer fatigue due to differences between perceived depth and focus, while holographic displays aim to address these issues but require advanced backlight units for effective beam steering and hologram image reproduction.
Innovation Solution
A backlight unit comprising a light source array with independently drivable light source blocks, a micro lens array, and a controller that selectively activates light sources to provide coherent light, allowing for beam steering and precise control of hologram image placement, integrated with a spatial light modulator and eye tracker for adaptive display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional 3D display methods (glasses-type or non-glasses-type) are used, then the display structure is relatively simple, but the depth perception consistency deteriorates and causes viewer fatigue
Solution Approach 1:
The light source array is divided into multiple light source blocks, where each block corresponds to a specific micro lens and can be independently controlled. This segmentation enables precise control of light beams for different spatial light modulator zones, achieving consistent depth perception across multiple viewing zones while maintaining a manageable structural complexity through modular organization.
Solution Approach 2:
The system dynamically controls the activation of light sources based on observer position detection. The controller selectively turns on or off specific light sources in real-time according to the detected observer location, enabling adaptive beam steering that maintains depth perception consistency without requiring a completely complex fixed structure for all possible viewing angles.
2Reliability
If holographic display methods are implemented, then full parallax and depth perception consistency are achieved, but the backlight unit complexity increases
Solution Approach 1:
The backlight unit is segmented into light source blocks that correspond to different spatial light modulator zones. Each light source block can be independently controlled to provide light for specific holographic viewing zones, enabling full parallax and depth consistency while managing complexity through this modular, zone-based organization.
Solution Approach 2:
The light source array serves multiple functions: it provides illumination for the spatial light modulator, enables beam steering to multiple viewing zones, and supports dynamic adaptation to observer position. This multi-functionality reduces the need for separate components, achieving holographic display capabilities without proportionally increasing overall complexity.
3Adaptability or versatility
If multiple light sources are activated for full viewing coverage, then the viewing zone coverage is improved, but the energy consumption increases
Solution Approach 1:
The system dynamically activates only the light sources corresponding to the detected observer position. When an observer is detected in a specific zone, only the light source blocks for that zone remain active, while others are turned off. This dynamic adaptation maintains full viewing zone coverage capability while significantly reducing energy consumption by activating only necessary light sources.
Solution Approach 2:
The system uses the eye tracker to automatically detect observer position and self-adjusts which light sources to activate. This self-service mechanism ensures optimal viewing zone coverage is maintained without manual intervention, while energy consumption is minimized by automatically deactivating unnecessary light sources based on real-time observer location.
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
Enables the creation of hologram images with consistent depth perception and full parallax, reducing viewer fatigue by dynamically adjusting light source activation based on observer positions, thereby enhancing the 3D display experience.
Implementation Method 1
Each of the plurality of micro lenses may be configured to collimate light incident from the plurality of light sources arranged in a corresponding one of the light source blocks as parallel light.
Implementation Method 2
When reference light is irradiated onto a hologram pattern having recorded thereon an interference pattern obtained by interference between object light reflected from an original object and the reference light, the reference light is diffracted and an image of the original object is reproduced.
Implementation Method 3
The plurality of light sources may be coherent light sources that emit coherent light.
Implementation Method 4
The plurality of light sources may be light-emitting diodes (LEDs) or laser diodes (LDs).
Data Source
AI summary
A beam steering backlight unit provides a hologram image to multiple viewing positions and a holographic display apparatus includes the beam steering backlight unit. The backlight unit includes a light source array comprising a plurality of two-dimensionally arranged light sources and a micro lens array arranged to face the light source array and comprising a plurality of two-dimensionally arranged micro lenses. The light source array includes a plurality of light source blocks each corresponding to a respective one of the plurality of micro lenses, wherein a plurality of the light sources are arranged in each of the plurality of light source blocks. The light source array is configured to select and turn on only those light sources of the plurality of light sources respectively disposed in a same position in each of the plurality of light source blocks and turn off the other light sources.