Digital Pixel Driving Circuit for Stable Grayscale in Micro LED Displays
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Solution Overview
Problem
Augmented reality display devices require high brightness and stable pixel driving due to the limitations of optical waveguides and the brightness of organic light emitting diodes, while inorganic micro or mini light emitting diode panels are suitable but face challenges in achieving the necessary pixel density and grayscale control.
Innovation Solution
A pixel driving circuit with a first circuit providing a driving current and a second circuit controlling the frequency and duration of the current based on digital signals to manage grayscale, utilizing transistors and latches to stabilize the display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If inorganic micro or mini light emitting diode panels are used to achieve high brightness, then light emitting intensity is improved, but pixel density and grayscale control become difficult to achieve
Solution Approach 1:
The pixel driving circuit is divided into two separate circuits: a first circuit responsible for providing driving current to the light emitting element, and a second circuit responsible for controlling the frequency and duration of the driving current based on digital signals. This segmentation allows each circuit to be optimized independently for its specific function, enabling both high brightness and precise grayscale control in mini LED displays.
Solution Approach 2:
The patent implements dynamic control of the driving current through the second circuit, which adjusts the frequency and duration of current pulses based on digital grayscale signals. This dynamic adjustment enables precise grayscale control (29, 216 gray levels) while maintaining the high brightness characteristics of mini LED, resolving the contradiction between fixed high intensity and variable grayscale requirements.
2Volume of moving object
If optical waveguide technology is used to achieve miniaturized structures, then device size is reduced, but optical loss increases requiring higher display brightness
Solution Approach 1:
The patent employs periodic pulsing of the driving current through the second circuit, which controls the frequency and duration of current delivery to the mini LED. This periodic action allows the display to achieve high peak brightness (compensating for optical waveguide losses) while maintaining small device size, as the mini LEDs are activated in controlled pulses rather than continuous operation.
Solution Approach 2:
The patent changes the operational parameters of the mini LED by controlling the frequency and duty cycle of the driving current pulses. By adjusting these parameters, the system can achieve the required peak brightness levels to overcome optical waveguide losses while maintaining the miniaturized structure benefits for augmented reality displays.
3Device complexity
If organic light emitting diodes are used, then device complexity is reduced, but brightness is insufficient for augmented reality displays
Solution Approach 1:
The patent introduces a second control circuit as an intermediary between the digital grayscale signals and the mini LED driving. This intermediary circuit processes digital signals to generate precise frequency and duration control for the driving current, enabling mini LED (which provide high brightness) to be controlled with the simplicity and precision of digital signaling, thus bridging the gap between organic LED simplicity and inorganic LED brightness.
Data Source
AI summary
A pixel driving circuit includes a first circuit and a second circuit. The first circuit is configured to provide a driving current to a light emitting element under the control of the second circuit; the second circuit is configured to receive a digital selection signal from at least one digital selection signal line, receive a digital data signal from at least one digital data signal line, and control a frequency and duration of the driving current received by the light emitting element during one frame of image, thereby controlling tahe grayscale of a sub-pixel having the light emitting element.