Data Driving IC Feedback Loop for Display Brightness Control
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Solution Overview
Problem
Light emitting displays struggle to emit light with desired brightness due to varying threshold voltages of transistors in pixels and lack of real current measurement and control.
Innovation Solution
A data driving integrated circuit that generates gradation voltage and current, compares pixel current with gradation current, and adjusts bit values to equalize them, ensuring consistent brightness across pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If transistors are provided in each pixel to supply current corresponding to data signal, then the light emitting display can emit light, but the brightness cannot be controlled precisely due to threshold voltage variations
Solution Approach 1:
The patent implements a feedback mechanism where the actual current flowing through each pixel is measured and compared with the target current. Based on this comparison, the data signal is adjusted to compensate for threshold voltage variations in transistors, enabling precise brightness control. The feedback loop continuously monitors and corrects the current to match the desired level.
Solution Approach 2:
The patent replaces the conventional direct current driving method with a voltage-based control system. Instead of directly controlling current through transistor gate voltages, the system converts data signals to voltages that are then converted to currents by pixel circuits, allowing for more precise control and measurement of the actual current flowing through each pixel.
2Ease of manufacture
If transistors with different threshold voltages are used in pixels, then manufacturing is simplified, but brightness uniformity deteriorates
Solution Approach 1:
The feedback mechanism measures the actual current in each pixel and adjusts the data signal to compensate for manufacturing variations in transistor threshold voltages. This allows pixels with different transistor characteristics to display uniform brightness by dynamically correcting for individual variations.
Solution Approach 2:
The patent changes the control parameter from direct current control to voltage control with current measurement. By controlling the voltage applied to each pixel and measuring the resulting current, the system can adapt to threshold voltage variations in transistors while maintaining brightness uniformity across the display.
3Device complexity
If no current measurement method is provided, then device complexity is reduced, but brightness control accuracy deteriorates
Solution Approach 1:
The patent introduces a feedback system that measures the actual current flowing through each pixel using dedicated measurement circuits. This measurement capability enables precise brightness control by comparing the measured current with the target current and adjusting the data signal accordingly, despite the increased device complexity.
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
Enables light emitting displays to achieve desired brightness by adjusting data bit values based on pixel current feedback, overcoming transistor threshold voltage variations.
Implementation Method 1
the light emitting display can emit light for itself by electron-hole recombination
Data Source
AI summary
A data driving integrated circuit to display an image with a desired brightness includes: a shift register adapted to generate sampling signals in sequence; a latch adapted to store external data in response to the sampling signal; a register adapted to temporarily store the data stored in the latch; a voltage digital-analog converter adapted to generate a gradation voltage corresponding to the data stored in the register; a current digital-analog converter adapted to generate a gradation current corresponding to the data stored in the register; a buffer adapted to supply the gradation voltage as a data signal to a pixel; and a data controller adapted to receive a pixel current flowing in the pixel in correspondence to the gradation voltage and fed back from the pixel and to adjust a bit value of the data stored in the register.