Projection Display Device Light Path Length Control for Depth Perception
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Solution Overview
Problem
Conventional stereoscopic image viewing methods restrict the horizontal parallax to a specific range, limiting the viewer's ability to perceive depth, leading to eyestrain or queasiness and restricting the number of depth gradations to around 24-32, which is insufficient for displaying images with larger depth ranges.
Innovation Solution
A projection display system that acquires pixel and depth values for each pixel, adjusts the light path length or reflection times based on depth values, allowing the viewer to perceive depth without relying on horizontal parallax, using a light output means, light guide body, and control means to adjust light path length or reflection times according to depth values, and optionally employs a reflecting member to change the angle of incidence and oscillate to maintain display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If horizontal parallax is increased to enhance depth perception, then the sense of three-dimensionality is improved, but the viewer experiences eyestrain or queasiness
Solution Approach 1:
The patent transitions from horizontal parallax (2D plane displacement) to vertical parallax (3D depth dimension). By controlling the light path length in the vertical direction through the light guide body and reflector, the system creates depth perception without horizontal displacement, thus avoiding eyestrain and queasiness while maintaining depth sensation.
Solution Approach 2:
The patent replaces the mechanical/displacement-based horizontal parallax system with an optical path length control system. Instead of moving images horizontally to create depth effect, the system uses controlled light path length variations through optical components (light guide body, reflector) to achieve the same depth perception effect without the harmful side effects of horizontal displacement.
2Ease of operation
If horizontal parallax is restricted to within a specific range to avoid eyestrain, then viewer comfort is improved, but the number of depth gradations is limited
Solution Approach 1:
The patent moves depth representation from the horizontal dimension to the vertical dimension through controlled light path length. This allows for a much larger range of depth gradations (up to 1000mm or more) while maintaining viewer comfort, as the vertical parallax does not cause the same eyestrain and queasiness as horizontal parallax.
3Measurement precision
If the number of pixels per millimeter is increased to improve image resolution, then display quality is improved, but the number of perceivable depth gradations decreases
Solution Approach 1:
The patent separates image resolution (horizontal/vertical pixel density) from depth representation (light path length). By encoding depth information in the vertical light path length dimension rather than relying on horizontal pixel displacement, the system allows high pixel density (3-4 pixels per mm) while maintaining a large number of perceivable depth gradations.
4Manufacturing precision
If light path length is extended to increase depth perception, then the sense of depth is improved, but light intensity is reduced
Solution Approach 1:
The patent introduces a light guide body as an intermediary component between the light source and the reflector. This light guide body efficiently transmits light over the extended vertical path length while maintaining high light intensity, acting as an optical mediator that prevents light loss during the depth-representing light path extension.
Solution Approach 2:
The patent uses a reflector with high reflectivity to redirect and intensify the light path. By strategically positioning the reflector and controlling the light path length, the system maintains or enhances light intensity even as the vertical light path length increases to represent greater depth.
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 viewer to perceive an image rich in depth without the limitations of horizontal parallax, allowing for a higher number of depth gradations and maintaining display quality by adjusting light path length or reflection times dynamically.
Implementation Method 1
a light guide body for guiding the light output per pixel from the light output means to a position corresponding to the pixel on a projection surface
Implementation Method 2
a reflector having light reflecting surfaces that oppose each other, and for guiding the light output per pixel from the light output means to a position corresponding to the pixel on a projection surface by reflecting the light with the light reflecting surfaces
Data Source
AI summary
A projection display device D includes an acquiring means 2 that acquires a pixel value Cg and a depth value Cz for each of a plurality of pixels constituting an image, a light output means 3 that outputs pixel display light Ld per pixel according to the pixel value, a light guide body 5 that guides the pixel display light Ld to a position corresponding to the pixel on a projection surface 8, and changes the light path length of the pixel display light Ld to the projection surface 8 according to the depth value Cz of the pixel. The light guide body 5 includes a reflector 51 that has mirror surfaces 511a opposing each other. The light path length control means 3 changes the number of times the pixel display light is reflected by the mirror surfaces 511a of the reflector 51 according to the depth value Cz of the pixel.