See-through Display Contrast via Polarization Modulation
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Solution Overview
Problem
Existing see-through display devices struggle to enhance image contrast ratio without being affected by ambient brightness, as the contrast ratio changes with varying ambient conditions, making it difficult to maintain consistent display quality.
Innovation Solution
A display device configuration that includes a light source emitting polarized waves, a light guide plate, and polarization modulation elements on both sides, with absorptive and reflective polarizing plates, where the second polarization modulation element is driven based on the gradation value of the image displayed on the first, to control light quantity and maintain contrast ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a see-through display adjusts luminances by modulating polarization of light from a light source, then the display allows objects on the back side to be seen through the screen, but the luminances increase at the same rate resulting in no change in display image contrast ratio
Solution Approach 1:
The display is divided into two separate polarization modulation elements (first and second polarization modulation elements) with different functions. The first element modulates light for see-through display with high transmittance, while the second element modulates light for image display with contrast enhancement, allowing each element to be optimized independently for its specific function
Solution Approach 2:
A light guide plate is introduced as an intermediary component between the light source and the polarization modulation elements. The light guide plate distributes light uniformly and directs it through the first polarization modulation element, enabling independent control of the light path for see-through and image display functions
2Manufacturing precision
If a projection display system displays video on a screen by irradiating with light based on video signal, then the contrast ratio is maximized when surroundings are dark, but ambient brightness changes cause contrast ratio to change
Solution Approach 1:
The second polarization modulation element receives image data and modulates the light path based on the image content and ambient conditions. By controlling the polarization state of light passing through it, it dynamically adjusts the contrast ratio to maintain optimal display quality under varying ambient brightness conditions
Solution Approach 2:
The display combines two polarization modulation elements with complementary functions - the first element optimized for high transmittance (see-through function) and the second element optimized for contrast control (image display function). This composite structure allows the display to achieve both see-through capability and ambient brightness adaptability
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 enhances contrast ratios for both still and video images by controlling light quantity effectively, maintaining display quality regardless of ambient brightness changes, and allowing for increased luminance and improved image display quality.
Implementation Method 1
a light source configured to emit light including a first polarized wave and a second polarized wave having a polarization axis perpendicular to a polarization axis of the first polarized wave
Implementation Method 2
absorptive polarizing plates respectively disposed on front-side and back-side surfaces of the first polarization modulation element
Implementation Method 3
a reflective polarizing plate disposed on a back-side surface of the second polarization modulation element
Implementation Method 4
Such a see-through display adjusts luminances for high and low gradation values by modulating the polarization of light from a light source
Data Source
AI summary
Provided is a display device enhancing an image contrast ratio and thereby enhancing display quality without being affected by ambient brightness. The luminance of an image displayed on a first liquid crystal panel in a display gradually increases in slope as a gradation value increases from 0 to 255. Accordingly, luminance A for the gradation value 0 is the same as conventional luminance a for the gradation value 0. However, luminance B for the gradation value 255 is higher than conventional luminance 2b for that gradation value, resulting in a high contrast ratio as expressed by the following equation:B:A=B/A:1>2b/a:1.