Display Panel Dimming Control for Low Grayscale Precision
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Solution Overview
Problem
Current dimming methods, such as PWM and DC dimming, face challenges in achieving accurate control of low grayscales due to limitations in duty cycle segmentation and power control, which affects luminous efficiency and color consistency.
Innovation Solution
A method and device for a display panel that involves determining a light-emitting stage based on the grayscale value, generating a dimming signal to control the light-emitting signal, and superposing a control signal to achieve precise grayscale control, with different control mechanisms for low and high grayscale values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PWM dimming method is used with duty cycle segmentation, then luminous efficiency and color consistency are improved, but control accuracy at low grayscales deteriorates due to minimum turning-on limit of transistors
Solution Approach 1:
The patent divides the dimming control into two separate stages: a first dimming stage using PWM duty cycle control for higher grayscales, and a second dimming stage using pulse amplitude control for lower grayscales. This segmentation allows each stage to operate in its optimal range, resolving the contradiction between maintaining reliability through PWM and achieving precision at low grayscales.
Solution Approach 2:
The patent transitions from one-dimensional duty cycle control to a two-dimensional control approach by introducing amplitude control as an additional dimension. The second dimming stage controls both the amplitude and duty cycle of pulses, enabling precise control at low grayscales where traditional duty cycle control alone is insufficient due to the minimum turning-on limit.
2Object-affected harmful factors
If DC dimming method is used to adjust brightness, then no strobef is generated, but control accuracy at low grayscales deteriorates due to high requirements for current or voltage ripple
Solution Approach 1:
The patent employs periodic pulse signals in both dimming stages, maintaining the advantage of PWM in controlling average brightness while avoiding continuous DC current adjustments. The periodic nature of the pulses allows for strobe-free operation while achieving the precision needed at low grayscales through amplitude modulation in the second stage.
3Measurement precision
If finer duty cycle segmentation is implemented for low grayscales, then control accuracy is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent changes the control parameter from duty cycle alone to a combination of amplitude and duty cycle in the second dimming stage. This parameter change enables coarse control through amplitude adjustment and fine control through duty cycle adjustment, achieving high precision without requiring extremely fine duty cycle segmentation, thus reducing system complexity.
Data Source
AI summary
A dimming method and device of a display panel, a storage medium, and a terminal equipment are provided. In a second dimming stage in a frame of one frame of an image, a grayscale of a light-emitting stage of the display is controlled by the light-emitting signal. In a first dimming stage in the frame of the image, the grayscale of the light-emitting stage of the display panel is controlled by superposing a control signal in the light-emitting signal. Therefore, in a low grayscale, the grayscale is realized by reducing an amplitude of the light-emitting signal.