Retarder and Polarizer Stack for Photosensor Light Sensing
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Solution Overview
Problem
Display devices face a challenge in maintaining consistent light sensing for photosensors due to the orientation of optical inputting devices, leading to reduced light transmission and sensitivity issues as users change their grip angle.
Innovation Solution
Incorporating a phase difference optical system with λ/4 retarders and polarizers, where the retarders are strategically positioned between the optical inputting device and the photosensor to ensure uniform light transmission regardless of the user's grip angle, by converting elliptically polarized light and maintaining its phase difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a polarizer is positioned between the photosensor and the optical inputting device, then light control capability is improved, but light sensing uniformity deteriorates due to grip angle variations
Solution Approach 1:
A retarder plate is introduced as an intermediary component between the polarizer and the optical inputting device. This retarder plate modifies the polarization state of incoming light, enabling the photosensor to detect light signals uniformly regardless of the optical inputting device's grip angle, thus resolving the contradiction between light control capability and light sensing uniformity
2Device complexity
If the polarizer is fixed in position, then device structure is simplified, but light transmission efficiency varies with grip angle
Solution Approach 1:
The retarder plate serves as a mediator that compensates for grip angle variations without requiring the polarizer to move or adjust. This maintains simple device structure while ensuring consistent light transmission efficiency across different grip angles by transforming the polarization state of incoming light
3Device complexity
If no retarder is used, then device complexity is reduced, but photosensor detection accuracy deteriorates under varying grip angles
Solution Approach 1:
The retarder plate is positioned between the polarizer and the optical inputting device to modify the polarization state of incoming light. This intermediary component ensures that the photosensor receives light with consistent polarization characteristics regardless of grip angle, thereby maintaining high detection accuracy without significantly increasing 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 solution enhances light sensitivity and maintains a consistent level of light transmission to the photosensor, improving the overall performance and usability of display devices by minimizing sensitivity loss due to user grip angle changes.
Implementation Method 1
a retarder disposed on the polarizer, wherein light of elliptical polarization from outside is converted by a λ/4 phase difference, and transmitted to the photosensor sequentially through the retarder and the polarizer
Implementation Method 2
the optical inputting device may generate elliptically polarized light having a phase value δ, and the variable retarder may have a phase difference of (λ/4)−δ
Data Source
AI summary
A display device includes an upper substrate, a lower substrate disposed opposite to the upper substrate, a photosensor disposed between the upper substrate and the lower substrate, a polarizer disposed on the upper substrate, and a retarder disposed on the polarizer, where light of elliptical polarization from outside is converted by a λ/4 phase difference, and transmitted to the photosensor sequentially through the retarder and the polarizer.