Progressive Eyeglass Lens Prism Layout for Convergence Relief
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Solution Overview
Problem
Conventional progressive power spectacle lenses generate unintended base out prisms due to convergence of the user's eyeballs, leading to excessive eye movement and discomfort.
Innovation Solution
The lenses are designed with a base in prism to counteract the unintended base out prism, ensuring that at least a part of the base out prism is cancelled, particularly in the portions where the main line of sight influenced by convergence passes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional progressive power spectacle lenses are designed with continuous power changes, then the lens provides multiple viewing distances, but unintended base out prisms are generated due to eyeball convergence
Solution Approach 1:
The patent applies preliminary anti-action by pre-calculating the convergence angle specific to each user and designing the progressive corridor and prism characteristics to counteract the expected base out prism before the user actually wears the lens. The main line of sight is deliberately deflected outward (away from the nose) to compensate for the inward convergence of the eyeballs, thus preventing the harmful prismatic effect before it occurs.
Solution Approach 2:
The patent applies local quality by making the prism characteristics location-dependent within the lens. Different regions of the lens have different prism values tailored to the local optical requirements and the user's specific convergence pattern. The prism power varies continuously across the lens surface, with specific focus on the corridor region where the main line of sight passes, to locally cancel the base out prism generated by convergence at each specific viewing point.
2Ease of operation
If the main line of sight is deflected toward the nose to accommodate convergence, then eye movement is reduced, but excessive convergence and discomfort occur
Solution Approach 1:
The patent applies inversion by doing the opposite of what conventional lenses do. Instead of deflecting the main line of sight inward toward the nose to accommodate convergence, the patent deliberately deflects it outward (away from the nose). This counterintuitive approach compensates for the inward convergence of the eyeballs, effectively canceling out the base out prism and preventing excessive convergence while maintaining natural eye movement patterns.
3Object-generated harmful factors
If base out prism is reduced by altering lens configuration, then convergence is minimized, but optical properties may be disrupted
Solution Approach 1:
The patent applies parameter changes by systematically varying multiple lens parameters including the deflection angle of the main line of sight, the prism power distribution, the corridor length, and the position of the progressive addition zone. These parameters are optimized based on the user's specific convergence angle to minimize base out prism while maintaining essential optical properties such as clear vision at all distances and minimal distortion in the peripheral zones.
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 design significantly reduces unnecessary eye convergence, enhancing user comfort by minimizing the prismatic effects caused by base out prisms.
Implementation Method 1
a shape of a base in prism is formed in a portion in which power continuously changes and through which a main line of sight, influenced by convergence of the user, passes
Data Source
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AI summary
The present invention provides a technology concerning a spectacle lens to suppress unnecessary convergence. In the spectacle lens, when an inner horizontal direction of the spectacle lens is a direction toward the nose of a user who wears the spectacle lens, and an outer horizontal direction of the spectacle lens is a direction toward an ear of the user, a shape of a base in prism is formed in a portion in which power continuously changes and through which a main line of sight, influenced by convergence of the user of the spectacle lens, passes such that at least a part of a base out prism, which may be generated in the portion, is cancelled.