Capacitive Driving Circuit for Display Voltage Accuracy
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Solution Overview
Problem
Display devices using organic EL or liquid crystal elements face challenges in reducing power consumption due to constant current flow in D/A converter and amplifier circuits, leading to low voltage accuracy and the need for temperature compensation.
Innovation Solution
A display device with a pixel circuit and a driving circuit that includes a first and second capacitance element, where the driving circuit alternately charges and discharges the second capacitance element based on pixel gradation, controlling the voltage signal for the data line, thereby reducing temperature's impact on transistor driving capability and eliminating the need for temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a constant current is applied to control the voltage of a data line, then the driving capability of the transistor is affected by temperature changes, but voltage accuracy of the data line becomes low
Solution Approach 1:
The patent applies periodic action by alternately repeating charging and discharging of the capacitance element a plurality of times during the data writing period. This periodic operation allows the voltage to be gradually built up with high accuracy while the transistor operates in a stable region, reducing temperature sensitivity and improving both voltage accuracy and temperature stability.
Solution Approach 2:
The patent uses the inherent capacitance element within the pixel circuit itself rather than adding a separate external capacitor. This self-service approach eliminates the need for additional components and allows the pixel circuit to serve its own voltage storage function, improving voltage accuracy without increasing device complexity.
2Power
If a D/A converter circuit or amplifier circuit is used to drive the data line, then the display device can operate, but power consumption increases due to constant current flow
Solution Approach 1:
The patent replaces continuous current flow with periodic charging and discharging of a capacitance element. By applying voltage only during the necessary data writing period and then maintaining it through capacitance, the system achieves full driving capability during active periods while dramatically reducing power consumption during idle periods when no current flows.
Solution Approach 2:
The patent maintains continuous voltage on the data line through the capacitance element after initial charging, eliminating the need for continuous current flow. The useful action of voltage maintenance is achieved through the stored electrical energy in the capacitor, allowing the display to operate continuously without constant power input.
3Measurement precision
If temperature compensation is implemented for transistor driving capability changes, then voltage accuracy improves, but device complexity increases due to additional components
Solution Approach 1:
The patent leverages the existing capacitance element within the pixel circuit to perform voltage storage and stabilization functions. By utilizing components already present in the pixel circuit design, the system achieves high voltage accuracy without adding external capacitors or temperature compensation circuits, thereby avoiding 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
This configuration improves voltage accuracy on the data line, simplifies the display device's design by eliminating the need for temperature sensors, and enhances power efficiency while maintaining high-quality display performance.
Implementation Method 1
a first switching circuit configured to alternately repeat charging and discharging of the second capacitance element, and is configured to control the charging and the discharging based on a gradation specified by the pixel circuit, and output a voltage signal corresponding to the gradation
Implementation Method 2
a first capacitance element provided between the data line and the driving circuit, wherein the driving circuit includes a second capacitance element
Data Source
AI summary
A display device includes a pixel circuit, a driving circuit configured to drive a data line coupled to the pixel circuit, and a first capacitance element provided between the data line and the driving circuit, wherein the driving circuit includes a second capacitance element, and a first switching circuit configured to alternately repeat charging and discharging of the second capacitance element, and is configured to control the charging and the discharging based on a gradation specified by the pixel circuit, and output a voltage signal corresponding to the gradation.