Optical Node Liquid Crystal Pixel Circuitry for Dynamic Range and S/N
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Solution Overview
Problem
The existing optical node devices using reflective liquid crystal display devices in wavelength selective switches (WSS) face limitations in signal-to-noise ratio (S/N) and dynamic range, which restrict the number of channels that can be effectively managed.
Innovation Solution
The optical node device incorporates a liquid crystal display device with multiple pixels having intersecting positive and negative polarity pixel data lines and row scan lines, along with specific transistor configurations to enhance dynamic range and improve S/N ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a reflective liquid crystal display device is used in a wavelength selective switch, then the optical signal routing function is achieved, but the dynamic range is limited and the S/N ratio is insufficient
Solution Approach 1:
The liquid crystal display device is divided into multiple pixels with independent transistor circuits. Each pixel has separate positive and negative polarity data lines with dedicated holding capacitors, allowing independent control and optimization of each pixel's electrical characteristics to expand overall dynamic range.
Solution Approach 2:
The patent introduces a time dimension by implementing alternating positive and negative polarity drive sequences. This temporal dimension allows the system to overcome the limited voltage range of single-polarity drives, effectively expanding the dynamic range through sequential voltage application in different polarities.
2Productivity
If the dynamic range of the reflective liquid crystal display device is expanded, then the S/N ratio and channel capacity increase, but the device structure becomes more complex
Solution Approach 1:
The transistor circuits in each pixel are designed to perform multiple functions: serving as switching elements, holding capacitors, and voltage regulation components. This multi-functionality reduces the need for additional separate components, thereby expanding channel capacity without proportionally increasing device complexity.
Solution Approach 2:
The patent changes the electrical parameters of the liquid crystal display device by implementing dual-polarity data lines and alternating voltage sequences. This parameter change allows the same physical device structure to achieve expanded dynamic range and increased channel capacity through optimized electrical drive conditions.
3Adaptability or versatility
If multiple pixels with intersecting data lines are used, then the optical signal management capability is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent employs asymmetric transistor circuit configurations within each pixel, with distinct positive and negative polarity data lines and separately positioned holding capacitors. This asymmetric design provides manufacturing tolerance by allowing independent optimization of each polarity's electrical characteristics, reducing the impact of alignment variations at pixel intersections.
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 expands the dynamic range and improves the signal-to-noise ratio, allowing for increased channel capacity and efficient management of optical signals in optical networks.
Implementation Method 1
a lens configured to condenses the light of each wavelength dispersed by the dispersive element onto a surface of the liquid crystal display device per wavelength and output light of each wavelength reflected by the liquid crystal display device toward the dispersive element
Implementation Method 2
output light of each wavelength reflected by the liquid crystal display device toward the dispersive element
Implementation Method 3
a liquid crystal display device with multiple pixels respectively provided at intersections at which multiple pairs of pixel data lines comprising of a positive polarity pixel data line to which a positive polarity pixel signal is supplied and a negative polarity pixel data line to which a negative polarity pixel signal is supplied
Data Source
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AI summary
An optical node device includes a liquid crystal display device. Each pixel includes a first transistor connected between a positive polarity pixel data line and a first holding capacitor and having a gate to which a row scan signal is supplied, a second transistor connected between a negative polarity pixel data line and a second holding capacitor and having a gate to which the row scan signal is supplied, a fifth transistor connected between a pixel electrode and a first source follower circuit to which a voltage from the first holding capacitor is input and having a gate to which a first control signal is supplied, and a sixth transistor connected between the pixel electrode and a second source follower circuit to which a voltage from the second holding capacitor is input and having a gate to which a second control signal turned on alternately with the first control signal is supplied. The fifth and sixth transistors have a threshold voltage different from that of other transistors of a first conductivity type.