Display Device Polarization Axis Control for Contrast
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Solution Overview
Problem
Conventional display devices face issues with visibility due to low contrast between characters and scales and the background, especially in varying light conditions, with strong outer light causing illumination parts to be seen undesirably and leading to deterioration in visibility.
Innovation Solution
A display device incorporating a backlight, a first polarizing plate with a ½λ phase difference plate for character and scale construction, and a second polarizing plate with polarizing plate controlling means to adjust the polarization axis relationship between the plates, allowing for improved contrast by blocking or transmitting light effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a diffuser plate with clouded color is used to block light, then the illumination part is obscured, but the color becomes visible and contrast deteriorates
Solution Approach 1:
The patent uses polarizing plates to control light transmission and blocking, achieving color-independent contrast. The first polarizing plate is affixed to the dial plate, and the second polarizing plate is rotated to change between parallel and orthogonal relations, allowing the dial plate to appear white or black without color interference from diffuser materials.
Solution Approach 2:
The patent changes the polarization state parameter by rotating the second polarizing plate between parallel and orthogonal orientations relative to the first polarizing plate. This parameter change enables dynamic control of light transmission, achieving high contrast without relying on color-based diffusion that compromises visibility.
2Illumination intensity
If a backlight is turned on in twilight, then the dial plate and character/scale both appear white, but the contrast between them deteriorates significantly
Solution Approach 1:
The patent uses polarizing plates to create extreme contrast states (white/black) independent of ambient light conditions. The 1/2λ phase difference plate on the dial plate interacts with the polarizing plates to ensure that character and scale regions deflect light differently, maintaining high contrast ratio in twilight conditions where conventional backlighting fails.
Solution Approach 2:
The patent introduces dynamic control through rotatable second polarizing plate that can be adjusted between parallel and orthogonal orientations. This dynamic adjustment allows the system to adapt to varying ambient light conditions (daytime, twilight, nighttime) and maintain optimal contrast ratio by changing the polarization state rather than relying on fixed brightness levels.
3Illumination intensity
If the polarization axis of the first polarizing plate is made parallel to that of the second polarizing plate, then light is transmitted for daytime viewing, but at night the contrast deteriorates when outer light enters
Solution Approach 1:
The patent employs dynamic reconfiguration of the polarizing plate system by rotating the second polarizing plate between parallel and orthogonal orientations. During daytime, the parallel orientation allows light transmission for clear viewing. During nighttime, the orthogonal orientation blocks transmitted light to prevent washout from outer light sources, maintaining contrast ratio adaptively rather than using a fixed configuration.
Solution Approach 2:
The patent changes the polarization angle parameter of the second polarizing plate relative to the first polarizing plate. By adjusting this parameter between 0° (parallel) and 90° (orthogonal), the system optimizes performance for different ambient light conditions, achieving both high light transmission during daytime and high contrast ratio during nighttime when outer light enters.
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 significantly enhances visibility by achieving a high contrast ratio, ensuring that characters and scales appear as a color extremely close to black, even under strong outer light conditions, thereby improving readability both day and night.
Implementation Method 1
a first polarizing plate arranged in front of the backlight, a 1⁄2λ phase difference plate for constructing a character and scale being affixed to the first polarizing plate; a second polarizing plate arranged between the backlight and the first polarizing plate or in front of the first polarizing plate
Implementation Method 2
a 1⁄2λ phase difference plate for constructing a character and scale being affixed to the first polarizing plate
Implementation Method 3
a 1⁄2λ phase difference plate for constructing a character and scale being affixed to the first polarizing plate
Data Source
AI summary
When a polarization axis of a first polarizing plate is parallel to that of a second polarizing plate, a light emitted from a backlight is transmitted, on the other hand, when a polarization axis of the first polarizing plate is orthogonal with that of the second polarizing plate, a light emitted from the backlight is mostly blocked off. A character and scale are constructed by a ½λ phase difference plate, so that the emitted light from the backlight, which enters to the character and scale, has a deflection direction reverse to that of the first polarizing plate. When the light emitted from the backlight is blocked, differently from a conventional artificial (pseudo) black color, a color extremely close to black color is seen. The contrast ratio and visibility are improved.