Saturation Mode Drivers for Solid-State Light Sources
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Solution Overview
Problem
Linear mode light drivers require significant headroom voltage and power supply capabilities to drive solid-state light sources, leading to increased cost and limited rapid switching capabilities, which can affect the contrast ratio and image quality in projection display systems.
Innovation Solution
The use of saturation mode current drivers with multiple current sources, rectifiers, and a shunt to eliminate AC bias and allow rapid switching of drive current, enabling efficient power management and increased on-time for the light source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If linear mode drive circuits are used to drive solid-state light sources, then the circuit design is simple and well understood, but significant headroom voltage and power supply capabilities are required, leading to increased cost
Solution Approach 1:
The patent changes the operating mode of the drive circuit from linear mode to saturation mode. This parameter change allows the circuit to operate with significantly lower headroom voltage requirements while maintaining the ability to drive high current levels. The saturation mode operation fundamentally alters the voltage-current relationship, enabling the use of lower voltage power supplies while still delivering the required drive current to the solid-state light source.
2Ease of manufacture
If linear mode drive circuits are used, then the circuit design is simple, but rapid switching capability is limited due to voltage dissipation requirements
Solution Approach 1:
The patent transitions from linear mode to saturation mode operation, which fundamentally changes the circuit's response characteristics. In saturation mode, the circuit can rapidly switch between states without being constrained by voltage dissipation requirements that limit linear mode switching speed. This enables the drive circuit to quickly turn on and off the solid-state light source, achieving microsecond-scale switching speeds suitable for high-frame-rate display applications.
3Illumination intensity
If high drive current is used to provide adequate light for projection systems, then the light output is sufficient, but power dissipation increases significantly
Solution Approach 1:
The patent changes the operating mode from linear to saturation, which alters the power dissipation characteristics. In saturation mode, the drive circuit can deliver high current to achieve the required light output while operating at lower voltage levels. This reduces the power dissipation in the drive circuitry itself, as the circuit operates more efficiently in saturation mode compared to linear mode at high current levels.
4Reliability
If the on-time of the light source is shortened to increase contrast ratio, then the minimum displayable light is reduced, but the circuit cannot rapidly switch due to voltage dissipation requirements
Solution Approach 1:
The patent changes the operating mode from linear to saturation, which enables rapid switching capability. This allows the circuit to quickly transition between on and off states, supporting short on-times necessary for high contrast ratio operation. The saturation mode operation eliminates the voltage dissipation constraints that would otherwise prevent rapid switching, enabling the circuit to achieve the required switching speeds for high-frame-rate display and high contrast ratio imaging.
Data Source
AI summary
System and method for driving solid-state light sources utilizing saturation mode current drivers. A preferred embodiment comprises charging a first drive circuit, discharging the first drive circuit into the solid-state light source, charging a second drive circuit, and discharging the second drive circuit into the solid-state light source. The alternating of the charging and discharging of two drive circuits ensures that there is a minimum amount of time without the capability of providing the drive current to solid-state light source. The use of saturation mode drive circuits ensures that it is possible to rapidly switch the solid-state light source on and off, improving the performance of the solid-state light source by minimizing the minimum amount of light producible by the solid-state light source, while reducing power consumption by eliminating the need to provide a headroom voltage.