Visual Function Test Device Using Virtual Image Optics
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Solution Overview
Problem
Conventional visual acuity tests require physical contact or the use of equipment that can be unsanitary or uncomfortable, especially for children, and may lead to inaccurate results due to unconscious visual acuity adjustment.
Innovation Solution
A visual function test device with a housing, peephole, and virtual image optics that form a virtual image of a visual target at a position visible from the peephole, with an exit pupil dimension less than the interocular distance and an eye relief of 5 cm or more, allowing non-contact examination without the need for equipment attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a visual acuity test is performed by blocking one eye with an occluder, then the test can be conducted using conventional methods, but the subject's unconscious visual acuity adjustment may cause inaccurate test results
Solution Approach 1:
The patent introduces an intermediary mechanism (the housing with peephole and virtual image optics) that mediates between the subject and the visual target. This intermediary structure guides the subject's eye movement and ensures that only the inspection eye can see the visual target, preventing unconscious adjustment while maintaining subject comfort without requiring occluders or forehead contact
2Reliability
If a forehead pad is used to fix the subject's forehead, then the visual acuity meter can be used, but it becomes unsanitary unless periodically disinfected
Solution Approach 1:
The patent extracts and eliminates the forehead pad component from the visual acuity testing system. Instead of requiring forehead contact for stability, the invention uses a housing with peephole and virtual image optics that provides stable testing through optical guidance alone, completely removing the sanitation issue associated with forehead pads
3Measurement precision
If polarized glasses or lens units are used to perform examination per eye, then eye-by-eye testing can be achieved, but it takes time and labor and children may be reluctant to wear such equipment
Solution Approach 1:
The patent uses the housing with peephole as an intermediary structure that inherently separates the visual paths for each eye. The peephole positioning and virtual image optics create a geometric constraint where only the inspection eye can access the visual target, eliminating the need for polarized glasses or lens units while maintaining eye-by-eye testing capability
Solution Approach 2:
The patent creates a virtual image copy of the visual target at a distance from the housing, allowing the subject to view the target through the peephole without direct line-of-sight exposure. This virtual image copying mechanism enables precise eye-by-eye testing through geometric optical path separation without requiring additional eyewear equipment
4Ease of operation
If the exit pupil dimension is larger than the interocular distance, then both eyes can see the visual target, but unconscious visual acuity adjustment occurs
Solution Approach 1:
The patent applies local quality by making the exit pupil dimension specifically smaller than the interocular distance, creating a localized optical constraint at the peephole. This localized dimensional constraint ensures that only the inspection eye can access the visual target through the peephole, preventing the non-inspection eye from seeing the target and eliminating unconscious visual acuity adjustment
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
Enables accurate and sanitary visual function testing without equipment contact, as the virtual image is only visible to the intended eye, reducing the likelihood of unconscious visual acuity adjustment and improving test reliability.
Implementation Method 1
virtual image optics accommodated in the housing, the virtual image optics being optics including a lens for forming a virtual image of the predetermined visual target at a position visible from the peephole
Data Source
AI summary
A visual function test device 1 is provided with a housing 10 with a peephole; a visual target display 11 accommodated in the housing 10 to display a predetermined visual target; and virtual image optics accommodated in the housing 10, the virtual image optics being optics including lenses 121, 122 for forming a virtual image of the predetermined visual target at a position visible from the peephole, the virtual image optics having an exit pupil of a predetermined dimension. The visual function test device has an eye relief of 5 cm or more. By using the visual function test device 1, a visual function test can be performed without the need to mount equipment on a subject.