Display Device Moire Control via Beam Spot Overlap
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Solution Overview
Problem
Existing display devices using optical element arrays and scanning lines are prone to the moire phenomenon, which degrades image quality due to the interaction between the optical element arrangement and scanning line pitch.
Innovation Solution
The display device controls the moire phenomenon by ensuring that the beam spot diameter in the sub-scanning direction and the arrangement pitch of micro optical elements are equal to or greater than the scanning line pitch, allowing for overlapping of adjacent beam spots and scanning lines to reduce intensity unevenness and contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the scanning line pitch is reduced to increase resolution, then the image detail is improved, but the moire phenomenon occurs due to interaction with the optical element array
Solution Approach 1:
The patent applies parameter changes by adjusting the scanning line pitch relative to the optical element array pitch. Specifically, it sets the scanning line pitch to be different from the optical element array pitch (preferably with a ratio not equal to 1:1), which changes the spatial frequency relationship between the scanning lines and the optical elements, thereby eliminating the moire phenomenon while maintaining high image resolution
Solution Approach 2:
The patent employs asymmetry by making the scanning line pitch asymmetric relative to the optical element array pitch. Instead of using equal or harmonically related pitches that cause constructive interference, the patent uses irregular or prime number ratio relationships between the two pitches, creating an asymmetric spatial frequency pattern that prevents moire formation
2Measurement precision
If the beam spot diameter is reduced to increase pixel density, then the display precision is improved, but the luminance unevenness increases due to insufficient overlap between adjacent beam spots
Solution Approach 1:
The patent applies partial or excessive action by making the beam spot diameter slightly larger than the minimum required for pixel density. Specifically, it ensures that adjacent beam spots overlap by a certain extent (the beam spot diameter is greater than the scanning line pitch), which provides excessive coverage that compensates for luminance variations at the boundaries between adjacent beam spots, thereby reducing overall luminance unevenness while maintaining high pixel density
Data Source
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AI summary
A display device includes a light source unit, a light deflector configured to deflect light from the light source unit, an optical element array configured to be two-dimensionally scanned in a main-scanning direction and in a sub-scanning direction with light via the light deflector 15, the optical element array having a plurality of optical elements, and a light projecting unit configured to project light received via the optical element array. In the display device, each of a beam spot diameter in the sub-scanning direction on the optical element array and an arrangement pitch of the optical elements in the sub-scanning direction on the optical element array is equal to or greater than a scanning line pitch on the optical element array.