Display Pixel Circuit Segmentation for Adjustable PWM Emission
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Solution Overview
Problem
Existing display technologies face challenges in efficiently adjusting the duty cycle and slope of the sweep signal for pulse width modulation (PWM) in display devices, leading to limitations in controlling the emission time of light-emitting elements.
Innovation Solution
A display device with a pixel circuit configuration that includes a first pixel circuit to generate a sweep signal changing linearly over time and a second pixel circuit to adjust the duty cycle of the current flowing through the light-emitting element, utilizing transistors and capacitors to control the voltage levels and slopes of the sweep signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional pixel circuit is used to generate sweep signal, then the circuit structure is simple, but the adjustment of sweep signal slope and duty cycle is limited
Solution Approach 1:
The pixel circuit is divided into two independent modules: a first pixel circuit dedicated to generating the sweep signal with adjustable slope, and a second pixel circuit dedicated to adjusting the duty cycle of the emission current. This segmentation allows each module to be optimized for its specific function, enabling flexible adjustment of sweep signal parameters without complicating the overall pixel structure.
Solution Approach 2:
The first pixel circuit generates a sweep signal that can be applied to multiple pixels simultaneously through a common electrode, making it a universal signal source. The second pixel circuit then individually adjusts the duty cycle for each pixel based on this universal sweep signal, combining multi-functionality with individualized control.
2Adaptability or versatility
If additional signal adjustment circuits are added to each pixel, then the sweep signal control is improved, but the pixel area increases
Solution Approach 1:
The first pixel circuit that generates the sweep signal is merged and shared across multiple pixels through a common electrode structure. This allows the sweep signal generation function to be combined at a higher level, eliminating the need for duplicate signal generation circuits in each pixel and thus saving pixel area while maintaining full control capability.
Solution Approach 2:
The sweep signal control is moved from the pixel level to the display panel level by applying the sweep signal to a common electrode that spans multiple pixels. This dimensional shift allows signal adjustment functionality to be implemented outside the individual pixel boundaries, preserving pixel area while enhancing control capabilities.
3Manufacturing precision
If the sweep signal is adjusted for each pixel individually, then the emission time control is precise, but the manufacturing complexity increases
Solution Approach 1:
The circuit is segmented into two functional modules with clear division of labor: the first pixel circuit handles sweep signal generation with precise slope control, and the second pixel circuit handles duty cycle adjustment. This segmentation enables precise emission time control through coordinated operation of specialized modules, simplifying the manufacturing process compared to implementing full control functionality in each pixel.
Data Source
AI summary
A display device includes a pixel, the pixel including: a light emitting element; a first pixel circuit including at least one capacitor and at least one transistor, and to generate a sweep signal that changes linearly over time from a voltage level of a data signal received through a data line; and a second pixel circuit including at least one transistor, and to adjust a duty cycle of a current flowing through the light emitting element based on the sweep signal.