Pixel Driving Circuit Voltage-Dividing Transistor High Grey Scale Control
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Solution Overview
Problem
Conventional pixel driving circuits using MOSFETs struggle to output exact current for high grey scales, leading to inadequate display control.
Innovation Solution
A pixel driving circuit is designed with a switch thin film transistor, a storage circuit, and a light driving circuit, incorporating a voltage-dividing transistor that adjusts resistance based on grayscale levels, allowing the circuit to operate in linear or saturation regions, and includes a control module to adjust supply voltage for precise current control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If MOSFET is used as driving transistor operated in saturation region, then the device can provide stable current drive capability, but a few change in gate voltage induces great change in drain current, causing inability to output exact current for high grey scales
Solution Approach 1:
The patent introduces a voltage-dividing transistor connected between the drain of the driving MOSFET and the cathode of the LED. This voltage-dividing transistor dynamically adjusts the voltage distribution in the circuit based on the operating conditions, enabling the driving MOSFET to operate in saturation region while reducing the sensitivity of drain current to gate voltage changes. The dynamic voltage division allows precise control of current for high grey scales while maintaining stable current drive capability.
2Measurement precision
If voltage-dividing transistor is added to the pixel driving circuit, then current control precision for high grey scales is improved, but the device complexity increases
Solution Approach 1:
The voltage-dividing transistor serves as an intermediary element between the driving MOSFET and the LED. It mediates the voltage and current relationship by providing a controllable voltage division ratio, which reduces the direct coupling between gate voltage changes and drain current changes. This intermediary structure enables precise current control without requiring complex circuit topologies or multiple additional components.
Data Source
AI summary
A pixel driving circuit and a mobile terminal are provided. The pixel driving circuit includes a switch thin film transistor, a storage circuit, and a light driving circuit. The switch thin film transistor receives data signal applied on the data line in response to scan signal applied on the scan line. The storage circuit is charged by the data signal. The light driving circuit emits light in response to the data signal. The light driving circuit includes a driving unit, light-emitting unit, a supply voltage end, a ground end, and a voltage-dividing transistor that is coupled between the driving unit and the ground end.