Integrated LED Module with On-Substrate Driver Transistor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing LED technologies face challenges in creating compact, cost-effective, and efficient solutions for controlling current through LEDs, especially when driving multi-colored LEDs or forming high-density RGB pixels, due to the need for separate driver circuits and interconnections, which increase size and cost, and can result in unintended light emission and reduced contrast in addressable arrays.
Innovation Solution
The integration of a drive transistor with the LED in a single module, featuring three terminals - a positive voltage terminal, a negative voltage terminal, and a control terminal - allows for active control of current through the LED, enabling parallel or addressable connections of LEDs of different colors, reducing sensitivity to voltage drops and parasitic paths, and allowing for compact, efficient, and cost-effective LED modules.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate driver circuits are used for each LED, then precise current control is achieved, but device size and manufacturing cost increase
Solution Approach 1:
The patent merges the LED and driver circuit into a single integrated device structure. The driver circuit is formed directly on the LED substrate, eliminating the need for separate driver circuits and reducing overall device size while maintaining precise current control capability.
Solution Approach 2:
The integrated driver circuit is designed to control multiple LEDs simultaneously through shared control lines. A single driver can address multiple LEDs in an array, reducing the total number of driver circuits needed and simplifying the overall system architecture.
2Measurement precision
If separate driver circuits are used for each LED, then precise current control is achieved, but manufacturing cost increases
Solution Approach 1:
The LED and driver circuit are manufactured together on the same substrate using compatible fabrication processes. This integration eliminates the need for separate manufacturing steps, assembly operations, and interconnections, thereby reducing manufacturing cost while maintaining precise current control.
Solution Approach 2:
The substrate is divided into multiple segments or regions, each containing an LED and its associated driver circuit elements. This segmentation allows for standardized manufacturing units that can be produced efficiently and assembled into larger displays.
3Productivity
If multiple LEDs are connected in parallel for high density RGB pixels, then pixel density increases, but unintended light emission occurs due to interconnect impedance
Solution Approach 1:
The LED and driver circuit are merged into a single integrated unit with well-defined electrical boundaries. This integration eliminates the interconnect impedance issues between separate components, preventing unintended current leakage and maintaining high light-to-dark contrast even when multiple LEDs are connected in parallel for high-density RGB pixels.
4Adaptability or versatility
If different color LEDs are used for color displays, then color versatility is achieved, but forward voltage mismatch problems occur
Solution Approach 1:
Each LED is integrated with its own driver circuit on the same substrate, allowing independent voltage regulation and current control. This integration compensates for forward voltage differences between different color LEDs (red, green, blue), enabling reliable color display operation without voltage matching issues.
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 enables compact, efficient, and cost-effective LED modules that can be connected in parallel or series for various applications, including color displays and white light sources, with each LED having its own driver for precise brightness control, reducing size and cost while improving light-to-dark contrast and handling process variations.
Implementation Method 1
LEDs are typically formed as dies having an anode terminal and a cathode terminal
Implementation Method 2
An LED is a two terminal electrical device with non-linear voltage versus current characteristics
Data Source
AI summary
An LED module is disclosed containing an integrated driver transistor (e.g, a MOSFET) in series with an LED. In one embodiment, LED layers are grown over a substrate. The transistor regions are formed over the same substrate. After the LED layers, such as GaN layers, are grown to form the LED portion, a central area of the LED is etched away to expose a semiconductor surface in which the transistor regions are formed. A conductor connects the transistor in series with the LED. Another node of the transistor is electrically coupled to an electrode on the bottom surface of the substrate. In one embodiment, an anode of the LED is connected to one terminal of the module, one current carrying node of the transistor is connected to a second terminal of the module, and the control terminal of the transistor is connected to a third terminal of the module.