LCD FAQ:
How does an LCD work?
What is the definition of liquid crystal?
Who discovered liquid crystals?
What does the acronym ITO stand for?
When referring to an LCD, what is the definition of Duty Rate?
When referring to an LCD what is the definition of Bias Ratio?
How is optimum Bias calculated for a given duty rate?
What are the common molecular phases of liquid crystal?
What is more commonly used in a TFT type LCD an STN or TN construction?
What type of interfaces are available on single-chip LCD controller/driver IC's?
What is contrast ratio?
How does an LCD work?
Liquid crystal (LC) fluids have unique physical and electrical properties. They flow like a liquid, but at a microscopic level have molecules that are not packed randomly (like a liquid). They exhibit a structure that is ordered like a solid crystalline material. These fluids are injected between thin glass sheets that are closely spaced together. On the inside of the glass sheets are microscopic grooves that allow the LC molecules arrange and order themselves. Also on the inside of these glass sheets are invisible, printed electrical conductive paths. These paths act like electrical wires and apply an electrical field to the liquid crystal fluid at specific locations. LC molecules have the ability to change the polarization of light and when an electrical field is applied to the fluid, the molecules alter their direction, redirecting light. Special light bending films, called polarizers, are laminated to the outside of the glass. These polarizers translate the different direction of the liquid crystal molecules into a pattern of bright and dark areas, called pixels. These pixels form the numbers, text or graphics that are seen on an LCD.
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What is the definition of liquid crystal?
Liquid crystals are a phase of matter whose order is intermediate between that of a liquid and that of a crystalline solid. The molecules are typically rod-shaped and about 25 Angstroms in length. The ordering function of these liquid crystal molecules is a function of temperature.
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Who discovered liquid crystals?
Liquid crystals were first discovered by an Austrian botanist Friedrich Reinitzer in 1888.
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What does the acronym ITO stand for?
The acronym ITO stands for Indium Tin Oxide. ITO is the conductive patterned layer in a Liquid Crystal Display.
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When referring to an LCD, what is the definition of Duty Rate?
The Duty Rate, also known as multiplex rate, is the fraction of total frame time that each row of the LCD is addressed. For example a 64 row passive display has a duty rate of 1/64th.
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When referring to an LCD what is the definition of Bias Ratio?
The Bias Ratio of an LCD is also known as the Voltage margin and is defined as the ratio of V on (voltage on pixels that are currently addressed to the ON-state) divided by V off (voltage on pixels that are not currently addressed).
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How is optimum Bias calculated for a given duty rate?
The formula for optimum bias is S =SQRT(duty rate) + 1.
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What are the common molecular phases of liquid crystal?
The most common molecular phases of liquid crystal are nematic, smectic, discotics, cholesteric, and lyotropic.
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What is more commonly used in a TFT type LCD? An STN or TN construction?
A Twisted-Nematic TN cell construction is the most common type used in a TFT LCD panel.
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What type of interfaces are available on single-chip LCD controller/driver IC's?
Almost all LCD single-chip controller/drivers can be interfaced by an 8-bit, 4-bit, or serial interface.
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What is contrast ratio?
The contrast ratio of an LCD is defined as the ratio of brightness (or luminance) of the pixel to the background. In all cases the numerator of the calculation should be the brighter value.
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