Observation Optical System Aberration Control via Brancher Segmentation
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Solution Overview
Problem
Conventional observation optical systems for electronic viewfinders struggle with aberrations and securing sufficient eye point length due to unclear optical characteristics and positioning of optical path branchers, especially when incorporating a visual line detecting function.
Innovation Solution
The optical system includes a first lens with positive refractive power, a second lens with negative refractive power, and a third lens with positive refractive power, with an optical path brancher disposed between the display panel and the first lens, satisfying specific inequalities to correct aberrations and secure a wide angle of view and sufficient eye point length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an optical path brancher is added to detect visual line, then visual line detection function is improved, but various aberrations occur and eye point length becomes insufficient
Solution Approach 1:
The optical system is divided into multiple lens elements (first lens with positive refractive power, second lens with negative refractive power, third lens with positive refractive power) to separately manage different optical functions. The optical path brancher is positioned between the display panel and the first lens to segment the optical path for visual line detection without interfering with the main imaging path, thereby controlling aberrations while maintaining detection functionality.
Solution Approach 2:
Specific parameters are defined and constrained: the absolute value of the radius of curvature of the first lens surface on the observation side is smaller than on the display panel side, and the inequalities 0.5 < d1/f < 2.0 and 0.01 < d23/d12 < 0.5 are satisfied. These parameter changes optimize the optical characteristics to control aberrations while accommodating the optical path brancher for visual line detection.
2Adaptability or versatility
If a negative lens with concave shape is used, then optical path branching is enabled, but eye point length becomes insufficient
Solution Approach 1:
Instead of using a single strong negative lens, the optical path branching function is achieved by positioning the optical path brancher between the display panel and the first lens. This segmentation allows the main lens system to maintain a longer eye point length while still enabling optical path branching for visual line detection.
Solution Approach 2:
The optical path brancher acts as an intermediary element positioned between the display panel and the first lens. It enables optical path branching without requiring a strong negative lens, thereby preserving eye point length while achieving the necessary functionality for visual line detection.
3Device complexity
If optical path brancher position is not clearly determined, then device complexity is reduced, but aberrations cannot be restrained
Solution Approach 1:
The position of the optical path brancher is precisely defined by the inequalities 0.5 < d1/f < 2.0 and 0.01 < d23/d12 < 0.5, where d1 is the distance from the display panel to the first lens surface and d23 is the distance from the second lens to the third lens. This parameter specification clearly determines the optimal position for aberration control while maintaining manageable device complexity.
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 configuration effectively corrects spherical aberration, curvature of field, and astigmatism, while maintaining a wide angle of view and sufficient eye point length, enabling accurate visual line detection and high imaging magnification.
Implementation Method 1
a first lens having a positive refractive power
Implementation Method 2
a second lens having a negative refractive power
Implementation Method 3
a third lens having a positive refractive power
Data Source
AI summary
An observation optical system includes, in order from a display panel side to an observation side, a first lens having a positive refractive power, a second lens having a negative refractive power, and a third lens having a positive refractive power, and an optical path brancher configured to branch an optical path, and disposed between a display panel and the first lens. An absolute value of a radius of curvature of a lens surface on the observation side of the first lens is smaller than that on the display panel side of the first lens. A predetermined condition is satisfied.