Electrochromic Filter for AR Sight Light Balance
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Solution Overview
Problem
Augmented reality sights face challenges in varying light conditions, where the intensity of the scene light significantly differs from the display light, leading to obscured or invisible images, and previous solutions like adjustable filters are inconvenient and degrade optical performance.
Innovation Solution
An optical assembly with an electrochromic filter and a control arrangement that automatically or manually adjusts optical transmittance based on light intensity, using a light sensor to balance the brightness of the scene and display images, ensuring clear visibility of both components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the brightness of the display is increased to match high intensity scene light in daylight conditions, then the display becomes visible, but the power consumption of the display and its associated circuitry increases significantly
Solution Approach 1:
An electrochromic filter is introduced as an intermediary element in the optical path between the objective lens and the display. This filter dynamically adjusts its optical transmittance based on ambient light conditions, thereby controlling the intensity of scene light reaching the display without requiring changes to display brightness. The filter acts as a mediator that balances the optical densities of the scene and display images, resolving the contradiction by attenuating scene light rather than increasing display output.
2Illumination intensity
If the brightness of the display is increased to match high intensity scene light, then the display becomes visible, but the comfort of the user is degraded due to excessive illumination
Solution Approach 1:
The electrochromic filter serves as an intermediary that selectively attenuates scene light intensity while allowing the display to maintain a comfortable, constant brightness level. By adjusting the filter's optical transmittance in response to ambient light conditions, the system ensures that the combined optical densities of scene and display images remain balanced, providing user comfort across varying lighting conditions without requiring increased display brightness.
3Illumination intensity
If adjustable irises or polarising filters are used to attenuate scene light, then the balance between scene and display brightness is improved, but the device complexity and ease of operation are degraded
Solution Approach 1:
The patent replaces mechanical adjustment mechanisms (such as adjustable irises) with an electrochromic filter that can be controlled electrically. This substitution eliminates the need for manual mechanical adjustment, reducing device complexity and improving ease of operation. The electrochromic filter's optical transmittance can be dynamically adjusted through electrical signals, allowing for automated or remote control without moving parts.
4Illumination intensity
If adjustable irises or polarising filters are used to attenuate scene light, then the balance between scene and display brightness is improved, but the ease of operation in the field is degraded
Solution Approach 1:
The electrochromic filter replaces manual mechanical adjustment systems with an electrically controllable solution. This allows the filter's optical transmittance to be adjusted automatically or remotely without requiring the user to physically manipulate mechanical components in the field. The electrical control mechanism significantly improves field usability by enabling quick, tool-free adjustments.
5Illumination intensity
If adjustable irises are used to attenuate scene light, then the brightness balance is improved, but light losses in the transmissive state occur
Solution Approach 1:
The electrochromic filter's optical transmittance is dynamically adjusted by changing its electrochromic state through applied voltage. In the transmissive state, the filter maintains high light transmission with minimal losses, unlike mechanical irises that inherently block some light. The parameter change in the filter's optical properties is achieved through electrochemical reactions that modify the material's transparency, allowing for efficient light transmission when attenuation is not required.
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 solution effectively adjusts the brightness of the scene light to match the display light, maintaining clear visibility of augmented reality images across different lighting conditions without increasing power consumption or degrading optical performance.
Implementation Method 1
an electrochromic filter mounted within said optical path and a control arrangement, the control arrangement being electrically connected to the electrochromic filter and operable to adjust the optical transmittance of the electrochromic filter
Data Source
Figure 1~2
AI summary
There is disclosed an optical assembly for viewing a scene. The optical assembly has an optical path extending from an objective end of the optical assembly to an eyepiece and is characterised by the provision of an electrochromic filter mounted within said optical path and an electrical control arrangement. The control arrangement is electrically connected to the electrochromic filter and is operable to adjust the optical transmittance of the electrochromic filter to thereby control the intensity of scene light which reaches the eyepiece along the optical path.