LTPS Palmprint Circuit Virtual Ground Parasitic Capacitance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a lack of palmprint recognition circuits and methods specifically designed for LTPS-TFT display panels, which are affected by changes in parasitic capacitance due to variations in circuit wiring.
Innovation Solution
A palmprint recognition circuit based on low temperature poly-silicon (LTPS) technology, comprising an optical signal collecting unit, a current signal amplifying unit, and a current signal detecting unit, that converts reflected light into a current signal, amplifies it, and detects the intensity to distinguish ridge and valley lines, thereby eliminating the influence of parasitic capacitance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional palmprint recognition circuit is used in LTPS-TFT display panel, then the display panel can be manufactured, but the recognition result is affected by changes in parasitic capacitance due to wiring variations
Solution Approach 1:
The patent creates a virtual ground node that replicates the electrical characteristics of a true ground, allowing the circuit to reference a stable potential point that is electrically isolated from parasitic capacitance variations in the wiring. This virtual copy of ground potential enables stable signal reference without direct connection to physical ground traces.
Solution Approach 2:
The patent introduces a ground simulation circuit as an intermediary element between the signal processing path and the physical ground. This intermediary virtual ground node mediates the reference potential, blocking the transmission of parasitic capacitance effects from the wiring into the signal path while maintaining proper circuit operation.
2Illumination intensity
If LTPS technology is used to reduce transistor area and improve aperture ratio, then display brightness and efficiency improve, but parasitic capacitance becomes more significant relative to signal levels
Solution Approach 1:
The patent extracts the ground reference function from the physical wiring structure and relocates it to a virtual ground node created by the ground simulation circuit. This separation removes the harmful coupling between signal paths and parasitic capacitance sources while preserving the necessary reference potential for signal processing.
Solution Approach 2:
The patent uses standard LTPS transistors and capacitors that are already part of the display panel manufacturing process to construct the ground simulation circuit. These existing components are repurposed to create the virtual ground, avoiding the need for additional specialized components or process steps.
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
The solution effectively detects palmprint features by stabilizing the amplified current signal and isolating the detection from parasitic capacitance effects, enabling accurate palm recognition without the interference caused by wiring changes in the circuit.
Implementation Method 1
an optical signal collecting unit, configured to collect an optical signal indicating a palmprint information and to convert the collected optical signal into a current signal
Data Source
AI summary
The disclosure provides a palmprint recognition circuit based on a LTPS technology, a palmprint recognition method and a display screen. The palmprint recognition circuit comprises an optical signal collecting unit, configured to collect an optical signal indicating a palmprint information and convert the collected optical signal into a current signal; a current signal amplifying unit, configured to amplify the converted current signal; and a current signal detecting unit, and configured to detect an intensity of the amplified current signal which indicates a ridge line or a valley line of the palmprint in the palmprint information. Therefore, it can solve the problem of having no palmprint recognition circuit and method for a LTPS-TFT display panel. This can eliminate an influence of a change of parasitic capacitance on the recognition result, wherein the change of parasitic capacitance is caused by a change of a wiring manner in the circuit.