Pixel Circuit Back-Gate Structure for Low-Frequency Flicker Control
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Solution Overview
Problem
Low-frequency driving methods for display devices increase leakage current, leading to luminance differences between frames and flicker phenomena, which affect the display's performance and power consumption.
Innovation Solution
The display device incorporates a pixel circuit with a light emitting diode, a driving transistor, and switching transistors with a dual-gate structure, including a common node and sub-transistors connected through a back-gate terminal, along with capacitors to manage voltage and reduce leakage current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a low-frequency driving method is used to reduce power consumption, then power consumption is reduced, but leakage current increases causing luminance differences between frames and flicker phenomena
Solution Approach 1:
The switching transistor is divided into two sub-transistors (third and fourth transistors) that are connected in parallel between the common node and the power supply terminal. This segmentation allows each sub-transistor to share the leakage current, reducing the total leakage current that flows into the storage capacitor and preventing luminance differences between frames.
Solution Approach 2:
A back-gate terminal is introduced as an intermediary element that overlaps the second sub-transistor. This back-gate terminal applies a bias voltage to control and reduce the leakage current of the switching transistor, thereby preventing harmful leakage current from affecting the storage capacitor while maintaining low power consumption operation.
2Loss of energy
If a low-frequency driving method is used to reduce power consumption, then power consumption is reduced, but flicker phenomena occur due to leakage current
Solution Approach 1:
The switching transistor is segmented into two parallel sub-transistors that share the leakage current burden. By dividing the single transistor into two parallel paths, the leakage current is distributed and reduced, preventing the accumulation of harmful leakage current that causes flicker phenomena during low-frequency driving.
Solution Approach 2:
The back-gate terminal serves as a mediator that actively controls the leakage current by applying a bias voltage to the second sub-transistor. This intermediary control mechanism suppresses the harmful leakage current before it can cause flicker phenomena, enabling stable low-frequency operation.
3Loss of energy
If the frame period is increased to enable low-frequency driving, then power consumption is reduced, but leakage current increases
Solution Approach 1:
The switching transistor is divided into two parallel sub-transistors during the extended frame period of low-frequency driving. This segmentation reduces the effective leakage current by distributing it across two parallel paths, allowing the longer frame period to be utilized without excessive leakage current accumulation.
Solution Approach 2:
The back-gate terminal acts as an intermediary control mechanism that actively manages leakage current during the extended frame period. By applying appropriate bias voltage to the second sub-transistor, the back-gate terminal suppresses leakage current even when the frame period is increased for low-frequency operation.
Data Source
AI summary
A display device includes a light emitting diode, a first transistor which transmits a driving current to the light emitting diode, at least one switching transistor connected to the first transistor and including a first sub-transistor and a second sub-transistor connected to each other through a common node, and a back-gate terminal connected to a first power supply and the common node, and overlapping the second sub-transistor.