Backlight Unit with Flexible PCB and Compensation Layers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional backlight assemblies for displays with passive pixels are often bulky, inefficient, and prone to visible artifacts, occupying excessive space in electronic devices.
Innovation Solution
A backlight unit with a row of light-emitting diodes mounted on a flexible printed circuit board, emitting light into a light guide layer, and incorporating color and luminance compensation layers to ensure homogeneous backlight illumination, along with a flexible printed circuit design that includes a stainless steel stiffener and varying trace pitch for improved robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional backlight assemblies are used, then backlight illumination is provided, but the assembly occupies excessive space and is bulky
Solution Approach 1:
The backlight assembly is segmented into discrete components: individual light-emitting diodes mounted on a flexible printed circuit board, separated from the light guide plate by spacers, with color compensation layers applied as separate elements. This segmentation allows compact arrangement while maintaining functional integrity and reducing overall assembly volume.
Solution Approach 2:
A flexible printed circuit board is used to mount the light-emitting diodes, allowing the backlight source to conform to the compact display geometry. The flexible circuit enables dense packing of LEDs in limited space while maintaining electrical connections, significantly reducing the volume occupied by the backlight assembly compared to rigid conventional structures.
2Area of stationary object
If light-emitting diodes are positioned close together to minimize inactive area, then display active area is maximized, but visible artifacts may occur
Solution Approach 1:
Color compensation layers are applied locally at specific positions within the light guide plate, particularly in regions where luminance non-uniformity occurs due to the close spacing of light-emitting diodes. This local quality adjustment corrects visible artifacts such as color shifts and brightness variations without requiring increased spacing between LEDs, thereby maintaining maximum display active area.
Solution Approach 2:
Color compensation layers with specific chromaticity values are introduced to counteract the color temperature variations and luminance non-uniformity caused by closely spaced light-emitting diodes. These layers modify the spectral composition of the backlight locally, eliminating visible artifacts while allowing the LEDs to remain positioned close together for maximum active area utilization.
3Illumination intensity
If color compensation layers are added to ensure homogeneous backlight, then luminance uniformity is improved, but device complexity increases
Solution Approach 1:
The spectral parameters of the backlight are modified by introducing color compensation layers with specific optical properties. These layers are positioned at strategic locations within the light guide plate to adjust the color temperature and luminance distribution, achieving homogeneous backlight illumination without requiring complex multi-component assemblies or precise alignment mechanisms.
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 configuration minimizes the size of inactive display areas, enhances backlight efficiency, and reduces visible artifacts, resulting in a more compact and robust display solution.
Implementation Method 1
The backlight unit may have a row of light-emitting diodes that are mounted on a flexible printed circuit board and that emit light into a light guide layer
Implementation Method 2
A light guide plate is used to distribute backlight generated by a light source such as a light-emitting diode light source
Data Source
AI summary
An electronic device includes display layers such as liquid crystal display layers and a backlight unit that provides illumination for the display layers. The backlight unit includes light-emitting diodes that emit light into the edge of a light guide film. To minimize the inactive area of the display, the light-emitting diodes are tightly spaced to approximate a line light source instead of point light sources. Color and/or luminance compensation layers are incorporated at various locations within the backlight structures to ensure that the backlight provided to the display layers is homogenous. A thin-film transistor layer of the display is coupled to a printed circuit board by a flexible printed circuit. The flexible printed circuit has additional solder mask layers to improve robustness, encapsulation, and traces with a varying pitch.