Pixel Unit Detection Switch for AMOLED Noise Compensation
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Solution Overview
Problem
In AMOLED display devices, external compensation circuits face significant errors in noise data extraction due to voltage floating caused by parasitic capacitors during the establishment of GOA levels, leading to inaccurate electrical data.
Innovation Solution
Incorporating a detection switch device in each pixel unit connected to a multiplexer, allowing for the acquisition of first data with noise caused by level jumps when the switch is open and second data including electrical data when closed, using an external compensation circuit with an operational amplifier, integrating capacitors, and an analog-to-digital converter to eliminate noise by calculating the difference between the two data sets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the multiplexer selects an acquiring channel to collect noise data of each pixel unit separately, then the external compensation circuit can acquire electrical data of pixel units, but voltage floating occurs during the establishment of GOA levels which couples to the sensing line through parasitic capacitors, resulting in large errors in noise data
Solution Approach 1:
The patent applies preliminary action by performing a reset operation before noise data acquisition. Specifically, a reset signal is sent to each pixel unit beforehand to initialize the detection switch device and eliminate residual voltages. This preliminary reset action ensures that when the multiplexer subsequently selects channels for noise data collection, the voltage floating caused by GOA level establishment does not introduce errors, as the system starts from a known stable state.
2Measurement precision
If the detection switch device is opened to acquire first data including noise data caused by level jump, then the noise can be separated, but the voltage floating and parasitic capacitor coupling still occur during multiplexer switching
Solution Approach 1:
The patent applies segmentation by dividing the noise data acquisition process into distinct time segments corresponding to different multiplexer channel selections. Each pixel unit's noise data is acquired in a separate time slot when the multiplexer selects its corresponding channel. The detection switch device is controlled to be opened during these segmented time periods, allowing noise data to be collected channel-by-channel without interference from voltage floating, as each measurement is isolated in time and space.
Solution Approach 2:
The patent implements periodic action through time-division multiplexing where the multiplexer periodically cycles through different pixel unit channels to acquire noise data. Each channel is selected for a specific time period, and this periodic switching pattern allows systematic collection of noise data from all pixel units. The detection switch device synchronizes its opened state with these periodic channel selections, ensuring that noise measurements are taken at regular intervals when the system is in a stable state.
Data Source
AI summary
An array substrate comprising a plurality of pixel units and an external compensation circuit; wherein, for each pixel unit of the plurality of pixel units, the pixel unit comprises a detection switch device, and the pixel unit is connected to a corresponding input end of a multiplexer of the external compensation circuit through the detection switch device; the external compensation circuit is configured: to acquire first data in a case that the detection switch device is opened, the first data comprising noise data caused by a level jump of the multiplexer of the external compensation circuit; to acquire second data in a case that the detection switch device is closed, the second data comprising the noise data and electrical data of the pixel unit; and to obtain the electrical data according to the first data and the second data.