Laser Projector Speckle Noise Reduction via Diffusion Member Positioning
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Solution Overview
Problem
Existing projectors using a lens member to split laser light and a diffusion member to diffuse it are ineffective in reducing speckle noise due to insufficient diffusion of laser light, leading to reduced diffusion components and inadequate averaging of speckle noise patterns.
Innovation Solution
A projector design where the diffusion member is positioned at a distance greater than the focal length of the lens member along the optical axis, allowing for increased diffusion of laser light and reducing speckle noise while preventing overlapping of split laser light, thereby maintaining image resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the diffusion member is positioned at the focal position of the lens member, then the laser light is sufficiently narrowed down, but the pitch of the diffusion portion becomes relatively large with respect to the spot diameter of the laser light, resulting in insufficient diffusion and inadequate speckle noise reduction
Solution Approach 1:
The patent changes the position parameter of the diffusion member from the focal position to a position beyond the focal position (at a distance of focal length or more from the optical principal surface of the lens member). This parameter change causes the laser light spot diameter to increase, which in turn increases the number of diffusion portions within the spot, thereby increasing diffusion components and improving speckle noise reduction effectiveness
2Measurement precision
If the diffusion member is positioned beyond the focal length to increase diffusion, then speckle noise reduction improves, but the split laser light may overlap, reducing image resolution
Solution Approach 1:
The patent optimizes the position parameter within a specific range (focal length or more from the optical principal surface) to achieve a balance: this position ensures sufficient diffusion for speckle noise reduction while preventing excessive spread that would cause overlapping of split laser light and degradation of image resolution
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
The projector effectively reduces speckle noise through sufficient diffusion of laser light, enhancing image quality by preventing overlapping of split laser light and maintaining image resolution.
Implementation Method 1
a lens member including a plurality of lens portions splitting the laser light scanned by the projection portion
Implementation Method 2
a diffusion member arranged to be opposed to the lens member, having an incident surface on which the laser light split by the lens member is incident and a diffusion portion diffusing the laser light incident from the incident surface
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
This projector (100, 200) includes a laser light generation portion (23, 24, 25), a projection portion (28) scanning laser light, and a speckle noise reducing projection screen (1). The projection screen includes a lens member (11) including a plurality of lens portions (111) splitting the laser light and a member (12) arranged to be opposed to the lens member, having an incident surface (122) and a diffusion portion. The diffusion portion of the diffusion member is arranged at a position apart by a distance larger than the focal length of the lens member along an optical axis (114) with respect to the optical principal surface (113) of the lens member.