Pixel Driving Circuit Gray Level Control via Variable Slope Scanning
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Solution Overview
Problem
Display devices using pulse-width modulation (PWM) signals face issues such as current accumulation, complex circuit designs, and screen flickers when driving LED panels, necessitating the development of more effective techniques for controlling light emission.
Innovation Solution
A display device with pixel driving circuits that include a light emitting element, a driving unit, and a control unit, where the driving unit adjusts current based on scanning signals with varying slopes and light emitting signals with enable and disable voltage levels, allowing for precise control of light emission periods to achieve desired gray levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If PWM signals are used to drive LED panels, then light emission control is achieved, but current accumulation occurs and circuit design becomes complex
Solution Approach 1:
The patent changes the control parameter from PWM duty cycle to direct current magnitude control. The driving circuit adjusts the current magnitude directly based on grayscale information, eliminating the need for PWM timing control and associated complex circuitry while maintaining precise light emission control.
Solution Approach 2:
The patent extracts and removes the PWM signal generation and timing control mechanisms from the display device. By using direct current control instead of PWM modulation, the complex timing circuits, counters, and control logic required for PWM operation are eliminated, simplifying the overall circuit design.
2Illumination intensity
If PWM signals are used to drive LED panels, then light emission control is achieved, but screen flickers occur
Solution Approach 1:
The patent changes from time-based PWM control to direct current magnitude control. By controlling the actual current flowing through the LED based on grayscale data without PWM modulation, the periodic switching that causes flicker is eliminated, providing stable illumination without flickering artifacts.
3Illumination intensity
If PWM signals are used to drive LED panels, then light emission control is achieved, but current accumulation occurs
Solution Approach 1:
The patent changes the control approach from PWM duty cycle modulation to direct current magnitude control. The driving circuit directly regulates the current magnitude according to grayscale information, ensuring precise current control without the accumulation issues that arise from PWM switching and duty cycle variations.
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 solution enables accurate control of gray levels and reduces flickers by carefully managing light emitting periods, improving the efficiency and performance of display devices.
Implementation Method 1
a light emitting element L2, a driving unit 240 and a control unit 220. The light emitting element L2 is configured to emit light according to a current I2
Data Source
AI summary
A display device includes pixel driving circuits. A first pixel driving circuit includes a light emitting element, first and second driving units and a control unit. The light emitting element emits light according to a current. The first driving unit generates the current. The second driving unit drives the first driving unit to adjust the current according to a first scanning signal. The control unit controls the first driving unit to adjust the current according to a first light emitting signal. The first scanning signal has first slope to third slopes during first to third periods, respectively. The first to third slopes are different from each other. The first light emitting signal has an enable voltage level during the first and third periods, and has a disable voltage level during the second period. The first to third periods are arranged continuously in order.