Projection Display Light Source Control for Contrast and Power
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Solution Overview
Problem
Existing projection video display apparatuses using independently controlled LED light sources struggle to adjust luminescence effectively without compromising contrast or increasing power consumption.
Innovation Solution
A projection video display apparatus with a controller that adjusts the lighting ratio and current value per unit time for each light source, employing a black display light source control mode to reduce the relative lighting ratio and current values of certain light sources more significantly during black signal input compared to white signal input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the lighting ratio and current value of each light source are adjusted to reduce power consumption, then power consumption decreases, but the contrast and luminescence adjustment capability deteriorates
Solution Approach 1:
The patent implements dynamic control of light source parameters by switching between multiple predetermined control modes (first through fifth modes) based on video signal characteristics. The controller dynamically adjusts lighting ratios and current values for each light source depending on whether the video is bright or dark, enabling adaptive luminescence control that maintains contrast while optimizing power consumption.
Solution Approach 2:
The patent changes operational parameters (lighting ratio and current value) of each light source based on different control modes. By predetermining multiple sets of parameter combinations and switching between them according to video brightness characteristics, the system achieves fine-grained luminescence adjustment that resolves the contradiction between power savings and contrast maintenance.
2Illumination intensity
If the lighting ratio per unit time for a light source with specific color is reduced more than other light sources in black signal display, then contrast is improved, but the overall luminescence adjustment range is limited
Solution Approach 1:
The patent segments the control of each light source (R, G, B) into independent controllable units with predetermined control modes. Each light source can be independently adjusted in terms of lighting ratio and current value, allowing selective reduction of specific color components during black signal display while maintaining overall luminescence adjustment versatility through multiple control mode combinations.
Solution Approach 2:
The system dynamically switches between five predetermined control modes depending on video signal characteristics. This dynamic adaptation enables the controller to achieve both high contrast (by selectively reducing specific light source output in black signals) and wide luminescence adjustment range (by selecting appropriate modes for different brightness conditions).
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 allows for higher adjustment of luminescence levels in independently controlled light sources, improving contrast and maintaining tone or shade of colors, especially during dark input signals while minimizing power usage.
Implementation Method 1
an LED (Light Emitting Diode) light source has been used in recent years. In this case, for example, light sources for three colors of red (R), green (G), and blue (B) are independently provided
Implementation Method 2
an illumination optical system configured to guide light generated by the plurality of light sources to the display element
Data Source
AI summary
A projection video display apparatus includes an input unit to input a video signal; a display to display the inputted video signal; a plurality of light sources to generate light; an illumination optical system to guide the generated light to the display; a projection optical system to project light via the display; and a controller to control the light sources, a lighting ratio and a current value per time for each light source. The controller has a black display control mode, for each light source, which makes a relative rate of a lighting ratio for a light source with a specific color smaller than the other light sources, and reduces the current value of the other light sources to be less than a current value of the light source with the specific color when compared with a case where the input video signal is a white signal.