Polarization Direction Measurement Without Reference Plate
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Solution Overview
Problem
Accurate measurement of the polarization direction of polarizing plates in liquid crystal displays is challenging due to the reliance on knowing the polarization direction of a reference polarizing plate, which complicates the process and can lead to reduced image quality if not accurately controlled.
Innovation Solution
A polarization direction measuring apparatus and method that includes a rotatable sample holder allowing the sample to be mounted in two directions, with a light source and detector to measure the polarization direction by detecting minimum light transmission angles, enabling accurate measurement without requiring known polarization directions of the reference polarizing plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the polarization direction of a reference polarizing plate is used for measurement, then the measurement process can be performed, but the measurement precision is reduced due to accumulated errors from the reference plate's unknown or inaccurate polarization direction
Solution Approach 1:
The invention extracts and eliminates the reference polarizing plate from the measurement system. By using a polarizing film with known polarization characteristics (the sample itself) as the measurement target rather than requiring a separate reference plate, the system removes the source of reference plate error accumulation. The measurement is performed by rotating the sample and detecting minimum light transmission angles, which directly yields the sample's polarization direction without dependency on reference plate accuracy.
Solution Approach 2:
The measurement system uses the sample's own optical properties to perform self-measurement. By utilizing the sample's birefringence characteristics and its interaction with polarized light, the system enables the sample to serve as both the object of measurement and the reference standard. The minimum light transmission angles detected during rotation directly reveal the sample's polarization direction, making external reference plates unnecessary.
2Ease of operation
If the reference axis of the sample holder is assumed to be aligned with the light source and detector, then the setup is simplified, but the measurement precision deteriorates because the reference axis alignment accuracy is unknown
Solution Approach 1:
The invention replaces the mechanical alignment system (relying on precise physical alignment of reference axis with light source and detector) with an optical measurement system. Instead of depending on mechanical alignment accuracy, the system uses optical detection of minimum light transmission angles during sample rotation to determine polarization direction. This substitution eliminates the need for precise mechanical reference axis alignment while maintaining high measurement precision.
3Reliability
If the polarization direction of the first polarizing plate is accurately controlled, then the image quality of the liquid crystal display is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The invention implements a feedback-based measurement system that determines the actual polarization direction of the sample through optical detection. By measuring the minimum light transmission angles during rotation and calculating the polarization direction from these measurements, the system provides feedback information about the sample's true polarization state. This enables post-manufacturing verification and adjustment, ensuring accurate polarization direction control without requiring extremely high manufacturing precision during assembly.
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 approach simplifies the measurement of polarization angles, ensuring accurate determination of the polarization direction of the sample polarizing plate, thereby improving image quality by eliminating the need to know the reference polarizing plate's direction.
Implementation Method 1
Light is generated by the light source 71, and the light detector 75 detects the quantity of light passing through the first polarizing plate 72 and the sample 74
Implementation Method 2
the light detector 75 detects when the minimum quantity of light is detected
Data Source
AI summary
A polarization direction measuring apparatus includes: a first polarizing plate having an unknown polarization direction about a reference axis; a sample whose polarization direction is to be measured; a rotatable sample holder on which the sample is mounted in a first direction and a second direction opposite to the first direction, wherein the sample holder rotates the sample along a reference axis in the azimuth direction; a light source that generates light passing though the first polarizing plate and the sample; and a light detector detecting light generated by the light source that passes though the first polarizing plate and the sample.