PWM Transistor and Current Source in Optoelectronic Light Emitting Device
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Solution Overview
Problem
Conventional LED displays using pulse-width modulation (PWM) have limited dynamic range and analog current dimming capabilities, and are constrained by the limitations of conventional TFT technology in achieving short PWM pulses.
Innovation Solution
An optoelectronic light emitting device comprising a semiconductor component, a current source, and a PWM transistor, where the current source is manufactured using TFT technology and the PWM transistor is made using a higher charge carrier mobility technology like crystalline silicon, allowing for a high dynamic range and cost-effective implementation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional TFT technology is used for the PWM transistor, then manufacturing cost is reduced, but dynamic range and modulation speed are limited
Solution Approach 1:
The device is segmented into two parts manufactured with different technologies: the current source is manufactured with conventional TFT technology for cost-effectiveness, while the PWM transistor is manufactured with crystalline silicon technology for high-speed modulation. This segmentation allows each component to be optimized for its specific function without requiring the entire device to use the more expensive high-performance technology.
2Productivity
If crystalline silicon technology is used for the PWM transistor, then dynamic range and modulation speed are improved, but manufacturing cost increases
Solution Approach 1:
High-performance crystalline silicon technology is applied locally only to the PWM transistor where fast switching and high dynamic range are critical for modulation, while the rest of the device (current source) uses conventional TFT technology. This local application of advanced technology optimizes performance where needed while controlling overall manufacturing costs.
3Adaptability or versatility
If analog current dimming is added to conventional LED displays, then dynamic range is improved, but device complexity increases
Solution Approach 1:
The patent replaces complex analog current dimming circuits with a simplified PWM-based control system using a crystalline silicon transistor. The high-speed switching capability of the crystalline silicon device enables precise PWM modulation that achieves wide dynamic range without requiring additional analog dimming circuitry, thereby reducing overall device complexity while maintaining versatility.
Data Source
AI summary
An optoelectronic light emitting device includes an optoelectronic semiconductor component configured to generate light, a current source configured to generate a current, and a PWM transistor driven by a pulse-width modulated signal. The PWM transistor enters a first state or a second state based on said pulse-width modulated signal. The PWN transistor is configured to supply the optoelectronic semiconductor component with the current generated by the current source in the first state and to decouple it from the current generated by the current source in the second state. The current source is manufactured by a first technology and the PWM transistor is manufactured by a second technology.