Backlight Assembly Light Shielding for LED Color Stability
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Solution Overview
Problem
Liquid crystal display (LCD) apparatuses experience inaccurate feedback control of red, green, and blue LEDs due to environmental changes like high temperature or humidity, leading to luminance reduction and color coordinate shifts, as the detected light amounts become inconsistent with initial settings.
Innovation Solution
A method and backlight assembly that detect the actual light ratios of red, green, and blue LEDs and compare them to reference ratios, using sensors and a controller to adjust the LEDs' output to maintain the desired color coordinates and prevent luminance variations, by converting analog values to digital and adjusting amplification to ensure the light ratios remain within specified ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If feedback control is used to maintain color coordinates of white light, then color accuracy is improved, but measurement precision deteriorates due to apparatus transformation in high temperature or humidity environments
Solution Approach 1:
A light shielding member is introduced as an intermediary component between the light source and light sensor. This member selectively shields certain wavelengths of light, creating a modified light path that allows accurate measurement of specific color components (e.g., red light) while blocking interference from other wavelengths. This resolves the contradiction by providing a reliable measurement mechanism that is insensitive to apparatus transformation, as the shielding effect remains consistent despite environmental changes.
Solution Approach 2:
The light shielding member is positioned at a specific location (edge of the light guide plate) and performs a specialized function of selective light blocking. Rather than uniformly treating all light, the system applies local quality control by shielding only specific wavelengths in a specific region, allowing accurate local measurement of color coordinates while maintaining overall system reliability under environmental stress.
2Use of energy by moving object
If the light source unit uses LEDs with low power consumption and high color reproduction, then energy efficiency is improved, but device complexity increases due to the need for feedback control systems
Solution Approach 1:
The light shielding member acts as a passive intermediary that simplifies the feedback control system. By physically blocking certain wavelengths before they reach the sensor, it eliminates the need for complex software-based wavelength discrimination or multiple sensors. The shielding member performs the discrimination function mechanically, reducing overall system complexity while maintaining the energy efficiency of LED-based backlighting.
3Adaptability or versatility
If the apparatus is maintained in high temperature or humidity environment for a long time, then adaptability is improved, but measurement precision deteriorates due to apparatus transformation
Solution Approach 1:
The light shielding member provides a stable reference for light measurement that is insensitive to apparatus transformation. Even when the display apparatus undergoes warping or dimensional changes due to environmental stress, the shielding member maintains its light-blocking function, ensuring that measurements taken through the shielded path remain accurate. This allows the system to adapt to environmental conditions while preserving measurement precision.
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 solution effectively maintains consistent white color coordinates and prevents luminance reduction in LCDs by accurately controlling the LEDs' output, even under environmental stressors that might warp the display apparatus.
Implementation Method 1
the light source unit typically uses LEDs having low power consumption and high color reproduction as the light source. Generally, there are a red diode generating red light, a green diode generating green light, and a blue diode generating blue light in the LED
Implementation Method 2
The red, green, and blue light generated from the red, green, and blue LEDs are mixed with each other to form white light
Implementation Method 3
a display apparatus should detect the amounts of the red, green, and blue light generated from the red, green, and blue LEDs
Data Source
AI summary
A method of driving light-emitting diodes (LEDs), a backlight assembly for performing the method, and a display apparatus having the backlight assembly are disclosed for various embodiments. For example, the backlight assembly includes a light source unit and a light source controller. The light source unit includes red, green, and blue LEDs generating red, green, and blue light, respectively. The light source controller detects amounts of the red, green, and blue light, respectively, to compare the actual light amount ratio of the red, green, and blue light with the reference light amount ratio. The light source controller controls the red, green, and blue LEDs, respectively, so that an actual light amount ratio becomes substantially identical to a reference light amount ratio when the actual light amount ratio is not identical to the reference light amount ratio.