Display Panel Current Driver With Fast Feedback Stabilization
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Solution Overview
Problem
Existing current drivers for LCD panels face challenges in achieving fast reaction speeds due to the need to drive high-voltage LED strings, which limits their ability to support increasing scan speed requirements with rising resolution and refresh rates.
Innovation Solution
A novel current driver design that includes a current source, current mirror, output enable switch, and control circuit, forming a feedback loop through the input channel to rapidly stabilize and control the driving current, while using a high-voltage output enable switch to handle the high power supply voltage of the LED strings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a high-voltage device such as a high-voltage transistor is used to drive the LED string, then the device can tolerate the high supply voltage of the LED string, but the reaction speed of the operational amplifier is limited and the circuit cost and load increase
Solution Approach 1:
The patent divides the driver circuit into two separate stages: a first stage that generates the driving current signal at low voltage, and a second stage that boosts the voltage to drive the LED string. This segmentation allows each stage to be optimized independently - the first stage prioritizes fast response speed while the second stage handles high-voltage requirements, thus resolving the contradiction between speed and voltage tolerance.
Solution Approach 2:
The patent introduces an intermediate voltage boosting stage between the operational amplifier and the LED string. This intermediary stage converts the low-voltage signal from the op-amp into a high-voltage signal suitable for LED driving, allowing the op-amp to operate at its optimal speed without being directly burdened by the high-voltage load.
2Manufacturing precision
If the resolution and refresh rate of the LCD panel are increased, then the display quality is improved, but the scan speed requirements increase which exposes the limitation of the current driver's reaction speed
Solution Approach 1:
By segmenting the driver circuit into two stages with distinct functions, the patent enables the first stage to operate at high speed to meet increasing scan rate requirements, while the second stage handles the power delivery. This allows the system to support higher resolutions and refresh rates without being bottlenecked by the driver's response speed.
Data Source
AI summary
A current driver having an input channel and an output channel includes a current source, a current mirror, an output enable switch and a control circuit. The current source is deployed in the input channel. The current mirror is deployed between the input channel and the output channel and coupled to the current source. The output enable switch is deployed in the output channel and coupled to the current mirror. The control circuit is coupled between the input channel and the output channel, to form a feedback loop through the input channel.