Polarization Control Element for Reflection-Type Liquid Crystal Display
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Solution Overview
Problem
Reflection-type liquid crystal display devices suffer from reduced Modulation Transfer Function (MTF) and increased power consumption due to the use of a semitransparent reflective sheet at an inclination, leading to astigmatism and inefficient light utilization.
Innovation Solution
A display device configuration that includes a light source, light guide plate, prism sheet, 1/4 wavelength plate, reflection-type liquid crystal display element, and a polarization control element arranged parallel to the light emitting surface, which splits light into polarized components and eliminates the need for a semitransparent reflective sheet, enhancing MTF and reducing power consumption by optimizing light usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a semitransparent reflective sheet is used to reflect light in a reflection-type liquid crystal display device, then the device structure is simplified, but the Modulation Transfer Function (MTF) is lowered due to astigmatism and light utilization efficiency is reduced
Solution Approach 1:
The invention extracts and removes the problematic semitransparent reflective sheet from the optical system. By eliminating this component, the source of astigmatism is removed, thereby maintaining high MTF performance while achieving the light reflection function through alternative means (the liquid crystal display element itself at 45-degree inclination)
Solution Approach 2:
The liquid crystal display element is given multiple functions: it serves both as the display medium and as the light reflection element. By positioning the liquid crystal display element at a 45-degree inclination, it performs both display and reflection functions, eliminating the need for a separate reflective sheet and avoiding the astigmatism problem
2Illumination intensity
If a semitransparent reflective sheet is used to reflect light, then only half of the polarized light can be utilized, but increasing light source quantity to brighten the image increases power consumption
Solution Approach 1:
The invention changes the orientation parameter of the liquid crystal display element to 45 degrees relative to the light guide plate. This parameter change enables the element to reflect both polarized light components effectively, doubling the light utilization efficiency and providing sufficient image brightness without increasing power consumption
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 enables the display of a bright image without lowering the MTF, reducing power consumption, and allowing for a longer operating time or smaller battery size in electronic viewfinders and similar devices.
Implementation Method 1
a 1/4 wavelength plate (12)
Implementation Method 2
a polarization control element (8) which is provided between the 1/4 wavelength plate (12) and the reflection-type liquid crystal display element (1)
Implementation Method 3
a prism sheet (5) configured to reflect light at a predetermined angle among the light emitted from the light emitting surface (32)
Implementation Method 4
a light guide plate (3) configured to receive light emitted from the light source (2), and emit the light from a light emitting surface (32)
Implementation Method 5
a reflection-type liquid crystal display element (1) that is provided at an inclination with respect to the light emitting surface (32)
Data Source
AI summary
A light guide plate (3) receives light emitted from the light source (2), and emits the light from a light emitting surface (32). A prism sheet (5) reflects light at a predetermined angle among the light emitted from the light emitting surface (32), allows the reflected light to enter the light guide plate (3), and transmits light at another angle. A polarization control element (8) is provided between a 1/4 wavelength plate (12) and a reflection-type liquid crystal display element (1) so as to be parallel to the light emitting surface (32). The polarization control element (8) splits the light emitted from the 1/4 wavelength plate (12) into first polarized light allowed to transmit as illumination light that enters the reflection-type liquid crystal display element (1) and second polarized light reflected so as to enter the light guide plate (3), and reflects the light modulated and emitted by the reflection-type liquid crystal display element (1) toward an imaging lens (10). The imaging lens (10) allows the incident light to go toward a combiner (21).