Pixel Circuit Using Reference Voltage to Reduce Power and Hysteresis
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Solution Overview
Problem
Display panels in flat panel displays, such as OLED and MicroLED panels, consume excess power due to the driving current of the light-emitting elements being based on the difference between a power voltage and a data voltage, leading to potential display quality deterioration from hysteresis in the driving switching elements.
Innovation Solution
A pixel circuit design that determines the driving current based on a reference voltage lower than the power voltage and incorporates complementary switching elements with specific gate signals to reduce power consumption and enhance display quality by minimizing hysteresis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If the driving current is determined based on the difference between power voltage and data voltage, then the light emitting element can be driven, but power consumption increases
Solution Approach 1:
The patent introduces a reference voltage that is lower than the power voltage to determine the driving current. By changing the voltage parameter from using full power voltage difference to using reference voltage difference, the power consumption is reduced while maintaining adequate driving current for the light emitting element
Solution Approach 2:
The patent introduces a dual switching element structure (fifth and sixth switching elements) that acts as an intermediary between the power voltage and the light emitting element. This switching structure controls current flow through the light emitting element based on gate signals, enabling precise control of driving current and reducing power consumption
2Reliability
If a driving switching element is used to control current flow, then current can be controlled, but hysteresis occurs and display quality deteriorates
Solution Approach 1:
The patent divides the driving switching function into two separate switching elements (fifth switching element and sixth switching element) instead of using a single switching element. This segmentation allows each switching element to be controlled independently by different gate signals, reducing hysteresis effects and improving display quality
Solution Approach 2:
The patent uses asymmetric control signals for the fifth and sixth switching elements. The fifth switching element receives a first gate signal while the sixth switching element receives a second gate signal, creating an asymmetric control structure that optimizes current flow and reduces hysteresis in the driving switching elements
Data Source
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AI summary
A pixel circuit includes a light emitting element, a first switch connected to first, second and third nodes, a second switch applying a data voltage to the second node in response to a writing gate signal, a third switch connecting the first and third nodes in response to a compensation gate signal, a capacitor connected to the first and fourth nodes, a fifth switch receiving a power voltage and connected to the second node, a sixth switch connected to the third node and an anode of the light emitting element, an eighth switch receiving a reference voltage and connected to the fourth node and a ninth switch receiving the power voltage and connected to the fourth node. One of the eighth and ninth switches is an N-type transistor and the other is a P-type transistor. Control electrodes of the fifth and sixth switches receive different signals.