Pulsed Backlight Unit for High-Resolution LCDs
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Solution Overview
Problem
Conventional liquid crystal displays (LCDs) face limitations in spatial resolution due to the need for three subpixels per pixel, which increases the size of the display and limits its resolution.
Innovation Solution
A display device with a backlight unit (BLU) that emits pulses of colored light, allowing each pixel to selectively pass portions of the pulsed light, eliminating the need for color filters and enabling smaller pixel sizes by sequencing red, green, and blue light emission, with a timing controller synchronizing the pulses to adjust color balance and duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If three subpixels per pixel are used to display color, then color display capability is improved, but spatial resolution is limited and pixel size increases
Solution Approach 1:
The patent applies periodic action by using a backlight unit that emits light in periodic pulses of different colors (e.g., red, green, blue) rather than continuous multi-color emission. Each pixel is programmed sequentially for each color pulse, allowing the display to achieve full color capability through time-multiplexed color emission instead of spatial subpixel arrangement. This temporal sequencing enables color display while reducing the need for three separate subpixels per pixel, thereby improving spatial resolution.
Solution Approach 2:
The patent transitions from a spatial dimension approach (three subpixels arranged side-by-side to provide red, green, and blue colors) to a temporal dimension approach (sequentially emitting red, green, and blue light pulses over time). By moving the color differentiation from space to time, each pixel can be smaller and more densely packed, improving spatial resolution while maintaining full color display capability through the time-multiplexed color sequencing.
2Ease of manufacture
If three subpixels per pixel are used, then color filters are needed in each pixel, but this increases pixel size and reduces spatial resolution
Solution Approach 1:
The patent extracts and removes the color filters from each pixel structure. Instead of having color filters embedded in every pixel, the color filtering function is transferred to the backlight unit, which emits already-filtered colored light pulses. This extraction eliminates the need for color filter materials within each pixel, reducing pixel size and allowing for higher spatial resolution while maintaining color display capability through the colored light pulses from the backlight.
Solution Approach 2:
The backlight unit acts as an intermediary that performs the color filtering function externally. Rather than each pixel containing its own color filters, the backlight unit serves as a mediator by emitting pre-filtered colored light pulses that then pass through the liquid crystal layer. This intermediary approach centralizes the color filtering function in one component, eliminating the need for repeated color filters in each pixel and reducing overall pixel area.
3Ease of manufacture
If color filters are included in each pixel, then color display is achieved, but manufacturing complexity and material usage increase
Solution Approach 1:
The backlight unit is given a multi-functional role, serving both as the light source and as the color filtering device. By making the backlight unit universal—capable of emitting multiple colors sequentially through pulsed emission—it eliminates the need for each pixel to have its own color filtering capability. This consolidation of functions reduces the total quantity of color filter materials required from the patent, as the filtering function is performed once by the backlight unit rather than being replicated in every pixel.
4Manufacturing precision
If pulsed colored light is used instead of continuous light, then spatial resolution is improved by reducing pixel size, but timing synchronization complexity increases
Solution Approach 1:
The patent applies preliminary action by programming the pixel states in advance before each colored light pulse is emitted. The liquid crystal display controller prepares the pixel configurations ahead of time, ensuring that each pixel is in the correct state to modulate the incoming colored light pulse. This preliminary programming approach allows for precise timing control and synchronization, managing the complexity of pulsed operation by preparing pixel states beforehand rather than requiring real-time coordination during pulse emission.
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 increases spatial resolution by reducing the size of pixels and eliminating the need for subpixels, while also allowing for higher brightness through the inclusion of white light pulses, and synchronizing the light emission with the LCD driver operations to achieve efficient color display.
Implementation Method 1
the BLU includes a light guiding plate and a plurality of light-emitting diodes (LEDs) arranged along one or more peripheries of the light guiding plate to emit pulses of the colored light
Implementation Method 2
Each pixel of an LCD includes a layer of liquid crystal molecules aligned between two transparent electrodes... By controlling the voltage applied across the liquid crystal layer in each pixel, light can be allowed to pass through the pixel in varying amounts
Data Source
AI summary
To increase the spatial resolution of a liquid crystal display (LCD) device, instead of emitting colors of an image (e.g., the three primary colors) in a single frame, the colors of an image are emitted sequentially. For example, if the colors of the image are red, blue, and green, the colors are emitted sequentially at a rate three times the desired frame rate of the display. The colors are emitted from a backlight unit (BLU) that produces pulses of colored light successively. By emitting colors sequentially, the number of subpixels in a pixel can be decreased or eliminated. Thus, among other advantages, the size of each pixel can decrease and the spatial resolution of the display device (e.g., pixels per inch) can increase.