Pixel Sensing Device Analog Front-End Circuit Parasitic Loading
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Solution Overview
Problem
Existing pixel sensing devices suffer from reduced accuracy due to parasitic resistances and capacitances in sensing lines, leading to a loading effect that degrades image quality and causes issues like burn-in, especially when pixel characteristics change over time or with environmental variations.
Innovation Solution
A pixel sensing device is designed with an analog-front-end circuit featuring an operational amplifier, current mirror transistors, and an integrating circuit to reduce the loading effect by separating the integrating circuit from the sensing line, using a sample and hold circuit to store voltage, and an amplifying circuit to enhance signal amplification before conversion to digital data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an integrated circuit is used to convert pixel characteristic current into voltage signal, then the pixel sensing function is achieved, but parasitic resistances and capacitances in sensing lines cause loading effect that deteriorates sensing accuracy
Solution Approach 1:
The patent segments the sensing system into two independent parts: a sensing line that only transfers current signals, and an integrated circuit that performs voltage conversion. By separating the integration function from the sensing line, the patent eliminates the loading effect caused by parasitic elements in the sensing line, as the integration capacitor is now located within the integrated circuit rather than being part of the sensing line.
Solution Approach 2:
The patent introduces an operational amplifier as an intermediary component between the sensing line and the integration capacitor. This operational amplifier acts as a buffer that isolates the sensing line from the capacitive load, preventing the parasitic capacitances in the sensing line from affecting the integration process and thereby maintaining high sensing accuracy.
2Area of stationary object
If sensing lines are made longer to cover more pixels, then the sensing coverage is increased, but parasitic resistances increase causing greater loading effect and accuracy deterioration
Solution Approach 1:
The patent applies segmentation by moving the integration function into the integrated circuit, which allows the sensing lines to remain short and localized to each pixel or pixel group. This segmentation enables extended sensing coverage through multiple independent integrated circuits while keeping each individual sensing line short, thus minimizing parasitic resistances and maintaining accuracy across the entire display panel.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration improves the sensing accuracy and performance of pixel sensing devices by minimizing the loading effect, allowing for more precise characterization of pixel characteristics and better image quality compensation.
Implementation Method 1
an amplifying circuit comprising an operational amplifier, which comprises a first input terminal, a second input terminal, and an output terminal
Implementation Method 2
an integrating circuit to integrate a current flowing into the second transistor
Implementation Method 3
a first transistor connected with the output terminal and a second transistor forming a current mirror circuit with the first transistor
Data Source
AI summary
The present disclosure provides, in a pixel sensing, a technology in which a parasitic impedance formed in a sensing line does not affect an integrating circuit using a current mirror circuit coupled with an operational amplifier.