Level Shift Circuit for LCD Camera Light Transmission
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Solution Overview
Problem
Liquid crystal display panels face challenges in achieving sufficient light transmission for cameras integrated within the display, particularly in modes like normally-black and normally-white, where insufficient light can lead to unclear images, especially when switching between visible and infrared light modes.
Innovation Solution
Incorporating a level shift circuit that selectively applies voltage levels to control electrodes, enabling three-value output and ensuring sufficient light transmission to cameras by driving control electrodes at higher voltage levels than pixel electrodes, thereby addressing light transmission issues in various display modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If control electrodes are driven at low voltage levels (same as pixel electrodes), then device complexity is reduced, but light transmission to cameras becomes insufficient
Solution Approach 1:
A level shift circuit is introduced as an intermediary component between the signal line driving circuit and the control electrodes. This circuit converts the low-voltage control signals into high-voltage drive signals, enabling sufficient light transmission to cameras while maintaining compatibility with the existing low-voltage control signal interface.
Solution Approach 2:
The level shift circuit dynamically changes the voltage parameter of control signals based on the display mode. In camera integration modes, it transforms low-voltage control signals into high-voltage drive signals to enhance light transmission, while in normal display modes, it maintains the original low-voltage operation to minimize complexity.
2Illumination intensity
If control electrodes are driven at high voltage levels to improve light transmission, then light transmission to cameras is enhanced, but device complexity increases
Solution Approach 1:
The level shift circuit is designed to perform multiple functions: it operates as a high-voltage drive circuit when cameras need to integrate, and as a pass-through for low-voltage signals during normal display operation. This multi-functionality allows the system to achieve enhanced light transmission only when necessary, reducing the impact on overall device complexity.
3Ease of operation
If low voltage control signals are used, then ease of operation is improved, but image clarity for cameras deteriorates
Solution Approach 1:
The level shift circuit serves as a mediator that preserves the ease of operation with low-voltage control signals while improving image clarity by converting these signals to high-voltage drive signals when camera integration is required, ensuring sufficient light transmission for clear image capture.
Data Source
AI summary
According to one embodiment, a level shift circuit includes a first input terminal, a second input terminal, an output terminal, a first level shift unit, a first inverter, a second level shift unit, a second inverter, and first to fourth switching elements. The first level shift unit outputs a first output voltage and a reference voltage. The second level shift unit outputs the reference voltage and a second output voltage.