Current Supply Circuit with Switch-Isolated Compensation for Display Devices
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Solution Overview
Problem
In display devices, variations in pixel characteristics and leakage currents can lead to undesired brightness and image quality deterioration, as existing current supply circuits fail to maintain stable voltages and prevent current leakage between transistors and capacitors.
Innovation Solution
A current supply circuit with a first transistor, a second transistor, a capacitor, and switches that adjust the input current and voltage, including a current compensation circuit to minimize voltage changes and prevent current leakage, allowing for precise control of pixel brightness and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitor is added to reduce voltage change of the driving transistor, then image quality stability is improved, but current leakage occurs between the capacitor and transistors causing brightness variation
Solution Approach 1:
A switch transistor is introduced as an intermediary component between the capacitor and the driving transistor. This switch transistor controls the connection state between these components, allowing the capacitor to store voltage for stability while preventing current leakage paths when the switch is in the off state. The switch acts as a gatekeeper that enables the beneficial voltage storage function while blocking the harmful leakage current.
2Use of energy by stationary object
If the same data voltage is supplied to all pixels, then power consumption is reduced, but brightness variation occurs due to pixel characteristic differences
Solution Approach 1:
The patent applies local quality by providing individual compensation circuits for each pixel. Each pixel's driving transistor has its own dedicated compensation circuit that includes a capacitor and switch transistor, allowing localized adjustment of voltage levels. This enables each pixel to receive customized voltage compensation based on its specific characteristics while maintaining overall system efficiency.
Solution Approach 2:
The patent changes the voltage parameter locally for each pixel through the compensation circuit. By adjusting the voltage stored in each pixel's capacitor based on its specific characteristics (such as threshold voltage variations), the system maintains brightness uniformity across all pixels. The switch transistor controls when this voltage parameter is set and maintained for each individual pixel.
3Object-generated harmful factors
If switches are added to control current paths, then current leakage is prevented, but circuit complexity increases
Solution Approach 1:
The patent merges the switch transistor with the existing pixel circuit structure. The switch transistor is integrated into the current path control mechanism, combining the functions of current control and leakage prevention into a single component that works in conjunction with the capacitor. This integration approach minimizes the increase in circuit complexity while achieving effective leakage prevention.
Data Source
AI summary
The present disclosure provides a current mirror circuit including a first transistor configured to be supplied with a data current from a data driving circuit; a second transistor configured to drive a light emitting diode by mirroring the data current transferred to the first transistor; a capacitor disposed between the first transistor and the second transistor and configured to store a voltage of a gate terminal of the second transistor therein; and a first switch disposed between the first transistor and the second transistor and configured to adjust an input current of the gate terminal of the second transistor.