Eyepiece-Connected Taking Optical System for TV Camera Heads
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Solution Overview
Problem
Conventional TV camera heads using small-format imaging devices face challenges with shading performance and focus adjustment due to the exit pupil position of the eyepiece lens, leading to interference and inadequate correction of aberrations, especially when the exit pupil position is not proximate to the taking lens or when filters and stops are interposed.
Innovation Solution
A taking optical system comprising a positive first group and a negative second group, with focus adjustment implemented by changing the spacing between the groups, ensuring the exit pupil is positioned on the object side of the imaging plane, and satisfying specific conditions to optimize refracting power and imaging magnification, thereby correcting aberrations and improving shading performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If a small-format imaging device is used to reduce camera head size and weight, then the focal length of the taking optical system must be shortened, but this causes the exit pupil position to lie on the image side, resulting in off-axis chief rays at an angle of convergence and deteriorated shading performance
Solution Approach 1:
The patent changes the optical parameters of the taking lens by positioning the exit pupil on the object side (negative position) rather than on the image side, and by adjusting the focal length and refracting power distribution. This allows the use of small-format imaging devices while maintaining proper ray angles for optimal shading performance.
2Length of moving object
If the focal length of the taking lens is shortened to accommodate small-format imaging devices, then the back focus becomes short, but this causes interference between the taking lens and imaging device during focus adjustment and makes it difficult to provide sufficient focus range
Solution Approach 1:
The taking optical system is divided into multiple lens groups with different refracting powers (positive and negative groups). This segmentation allows independent adjustment of each group to achieve focus while maintaining adequate back focus distance, preventing interference between the taking lens and imaging device.
Solution Approach 2:
The patent introduces a new spatial arrangement by positioning the exit pupil on the object side and creating specific spacing relationships between lens groups and the imaging device. This dimensional reconfiguration provides sufficient focus adjustment range without requiring excessive back focus length.
3Length of stationary object
If the exit pupil position of the eyepiece lens is not proximate to the taking lens or filters and stops are interposed, then the optical path is extended, but this causes the exit pupil position of the taking lens to lie on the image side, worsening the match with imaging device shading performance
Solution Approach 1:
The patent changes the exit pupil position parameter to lie on the object side (negative position), which compensates for the extended optical path length caused by filters and stops. This parameter adjustment restores proper alignment between the taking lens and imaging device for optimal shading performance.
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 allows for effective focus adjustment and aberration correction, enhancing shading performance and reducing interference, while maintaining a compact design suitable for small-format imaging devices in TV camera heads.
Implementation Method 1
A taking optical system comprising, in order from its object side, a positive first group and a negative second group, characterized in that focus adjustment is implemented by changing the spacing between the first group and the second group
Implementation Method 2
satisfying specific conditions to optimize refracting power and imaging magnification, thereby correcting aberrations and improving shading performance
Data Source
AI summary
The invention relates to an eyepiece-connected taking optical system well fit for TV camera heads using a small-format imaging device. The taking optical system comprises a field direction turning member 1P, 2P, a positive first group and a negative second group. The first group comprises a positive cemented lens convex on its object side, a positive single lens convex on its object side and a positive cemented lens convex on its object side, and the second group comprises a negative single lens. Focus adjustment is implemented by changing a spacing t2 between the first group and the second group. The taking optical system satisfies condition (1) for defining the position of the front focus with respect to the taking lens, condition (2) for defining the refracting power of each lens group, condition (3) for defining the imaging magnification of the second group, and condition (4) for defining the profile of refracting power in the first group.