Pixel Drive Circuit With PWM Control for Low-Grayscale Uniformity
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Solution Overview
Problem
OLED display screens suffer from poor uniformity in low grayscale display.
Innovation Solution
A pixel driving circuit with a first control circuit that adjusts the duration of a voltage signal at the first power supply terminal based on an enable signal, using a voltage difference between nodes to provide a driving current, and includes a fifth transistor to regulate the duty cycle of the enable signal, thereby controlling the driving current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional OLED display is used, then the display can show images, but the uniformity of low grayscale display is poor
Solution Approach 1:
The pixel drive circuit is segmented into multiple functional modules: a drive transistor for current control, a fifth transistor specifically for PWM signal input, a first control circuit for PWM signal processing, and a first reset circuit. This segmentation allows each module to perform its specific function optimally, with the fifth transistor and first control circuit enabling precise grayscale control through PWM while the drive transistor maintains stable current output, thereby improving display uniformity without requiring complete redesign of the entire circuit.
Solution Approach 2:
The first control circuit is designed to perform multiple functions: it processes PWM signals from the fifth transistor, controls the drive transistor's operation, and works with the first reset circuit to maintain proper circuit states. This multi-functionality allows the circuit to handle both grayscale control and drive management within a single integrated block, improving display uniformity while avoiding the need for separate dedicated circuits for each function.
2Manufacturing precision
If a pixel drive circuit with first control circuit and fifth transistor is added, then display uniformity at low grayscale is improved, but the circuit complexity increases
Solution Approach 1:
The circuit incorporates dynamic control through the fifth transistor and first control circuit that respond to PWM signals. The fifth transistor dynamically adjusts its conduction state based on the PWM signal duty cycle, enabling the drive transistor to modulate its output current dynamically. This dynamic operation achieves precise grayscale control and uniform display performance without requiring multiple static circuit configurations.
Solution Approach 2:
The invention utilizes parameter changes in the PWM signal (duty cycle variation) to control grayscale levels. By changing the duty cycle parameter of the PWM signal input to the fifth transistor, the circuit achieves different grayscale outputs from the drive transistor. This parameter-based control method improves grayscale uniformity while avoiding the need for multiple physical circuit variants for different grayscale levels.
Data Source
AI summary
A pixel drive circuit and a drive method therefor, and a display panel and a display apparatus. The pixel drive circuit includes a drive circuit and a first control circuit, wherein the drive circuit is connected to a first node, a second node and a third node, and the drive circuit is used for providing, in response to a voltage signal of the first node, a drive current by using a voltage difference between the second node and the third node; and the first control circuit is connected to the second node, a first power source end and an enable signal end, and the first control circuit is used for transmitting a voltage signal of the first power source end to the second node in response to a signal of the enable signal end.