Passive Matrix LED Assembly for Low-Cost Image Display
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Solution Overview
Problem
Conventional automotive display technologies, such as LCDs and OLEDs, are inefficient in terms of power consumption and manufacturing complexity, while active matrix LED displays are costly to produce for simple communication tasks like vehicle-to-pedestrian information transfer.
Innovation Solution
A passive matrix LED display assembly using a free-floating matrix of conductor lines and direct-emitting LED packages, where each LED is mounted on an interposer, allowing for low-cost manufacturing and simple image generation with coarse resolution, utilizing bias voltages to turn LEDs on and off for image display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional LED active matrix displays are used, then high resolution and image quality are achieved, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The display is segmented into a passive matrix structure with row and column conductor lines intersecting to form pixel locations. LED packages are placed only at intersection points rather than requiring individual transistors and capacitors for each pixel, significantly reducing component count and manufacturing complexity while maintaining adequate image quality for communication purposes
Solution Approach 2:
The patent uses relatively large, inexpensive LED packages (e.g., 5mm x 5mm or larger) instead of expensive, precision-mounted chip-scale LEDs. These larger packages are easier and cheaper to manufacture and assemble, and are sufficient for the application's needs since high resolution is not critical for pedestrian communication displays
2Ease of operation
If conventional LED active matrix displays are used, then individual pixel control is achieved, but cost and manufacturing complexity increase
Solution Approach 1:
Multiple conductor lines (rows and columns) are merged into a single matrix structure where intersections define pixel locations. This allows individual pixel control through the intersection of activated row and column lines without requiring separate control circuitry for each pixel, reducing manufacturing cost and complexity while maintaining operational control
Solution Approach 2:
The conductor lines serve multiple functions: they provide structural support, electrical connection, and pixel addressing. The intersection of row and column lines universally defines all pixel locations in the display, creating a scalable and cost-effective control mechanism that works across different display sizes and resolutions
3Illumination intensity
If LCD displays are used, then image display capability is achieved, but power consumption increases significantly
Solution Approach 1:
LED packages are self-emissive light sources that generate their own light through electroluminescence, eliminating the need for separate backlight units and complex liquid crystal filtering systems. This self-service capability provides adequate illumination for the application while consuming significantly less power than LCD systems, which can absorb up to 75% of backlight light
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 provides a cost-effective and efficient means to communicate simple information to pedestrians or other vehicles, reducing manufacturing complexity and power consumption, while ensuring the image is visible in various conditions with sufficient brightness.
Implementation Method 1
an n x m array of direct-emitting LED packages arranged over the row/column intersections. An LED package comprises a single LED mounted on an interposer
Data Source
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AI summary
The invention describes a passive matrix single-color LED display assembly (1) comprising a matrix (10) of row conductor lines (11) and column conductor lines (12); an array of direct-emitting LED packages (20), wherein the anode (21) of each LED package (10) is electrically connected to one of the row conductor lines (11) and the cathode (22) of that LED package (20) is connected to one of the column conductor lines (12); and a driver (40) configured to apply a bias voltage to a row conductor line (11) and to apply a bias voltage to a column conductor line (12) according to an image (71, 72, 73) to be displayed.