Display Pixel Circuit Segmentation for Grayscale Control
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Solution Overview
Problem
As the requirement for higher levels of grayscales increases, existing light emitting devices require larger driving circuits to manage the increased complexity, leading to inefficiencies in display performance.
Innovation Solution
The light emitting device employs a pixel circuit with a current control circuit and a pulse width modulation (PWM) circuit, receiving analog signals and digital signals with reference pulse signals to generate driving currents and PWM pulses during specific sub-frames, allowing for a variety of grayscale combinations while maintaining a relatively small driving circuit scale.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If current control is used to generate a variety of currents for pixels to display multiple levels of grayscales, then grayscale display capability is improved, but the scale of the driving circuit increases
Solution Approach 1:
The patent divides the grayscale display task into two independent parts: (1) current control circuit that generates driving current based on analog signal, and (2) PWM circuit that generates pulse width modulation signals based on digital signals. By segmenting the grayscale control into separate current control and pulse width control functions, the system achieves high grayscale capability without requiring a single large complex circuit, thus resolving the contradiction between grayscale display capability and driving circuit scale.
Solution Approach 2:
The patent transitions from traditional single-dimension current control to a two-dimensional control approach by combining analog signal-based current control with digital signal-based PWM control. This dimensional expansion allows the system to achieve higher grayscale levels through the combination of two control dimensions (current magnitude and pulse width) rather than relying on a single complex control circuit, thereby improving grayscale capability while keeping the driving circuit scale manageable.
2Measurement precision
If the requirement of levels of grayscales increases, then grayscale precision is improved, but the scale of the driving circuit increases
Solution Approach 1:
The patent segments the grayscale precision requirement into two independent control paths: the current control circuit handles the analog signal for precise current generation, while the PWM circuit handles digital signals for precise pulse width control. This segmentation allows each circuit to be optimized for its specific function with appropriate precision, achieving high overall grayscale precision without requiring one large complex circuit that would increase driving circuit scale.
Solution Approach 2:
The patent introduces an intermediary PWM circuit that acts as a mediator between the digital control signals and the light emitter. The PWM circuit converts digital grayscale values into precisely controlled pulse widths, which then modulate the analog driving current from the current control circuit. This intermediary approach enables high grayscale precision through the combination of digital precision and analog control, without requiring the current control circuit itself to handle the full complexity of high-precision grayscale generation.
Data Source
AI summary
A light emitting device and a light emitting method are provided. The light emitting device includes a plurality of sub-pixels. Each of the sub-pixels displays a grayscale during a frame. The frame includes N sub-frames. Each of the sub-frames include a scan period and an emission period. Each of the sub-pixels include a pixel circuit and a light emitter. The pixel circuit include a current control circuit and a pulse width modulation (PWM) circuit. The current control circuit receives an analog signal, and outputs a driving current according to the analog signal. The PWM circuit receives M digital signals and M reference pulse signals, and outputs a PWM pulse according to the M digital signals and the M reference pulse signals. The light emitter receives the driving current and the PWM pulse during emission period of each of the N sub-frames.