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How is the brightness on a LCD module defined? |
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It is the average brightness measured from 9 surface areas of the display. The surface is divided into 9 equivalent partitions and the brightness is measured from center of each partition. |
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What is cd/m^2? |
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It is the acronym of Candela per squared meter that represents the unit of brightness. Candela has another term of “nit”. |
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How is the contrast ratio on a LCD module defined? |
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Brightness measured when LCD is at “white state"
Contrast ratio (CR) = ----------------------------------------------------------------------------------
Brightness measured when LCD is at “black state” |
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How is the resolution on a LCD module defined? |
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It is the number of color pixels over the surface area of a LCD module. It is calculated by the numbers of pixels in the row and in the column. |
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What are the standard resolutions? |
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‧ QVGA |
320(H)x240(V) pixel
240(H)x320(V) pixel |
2.2” , 2.4” , 3.2” , 3.5” , 5.7” |
‧ WQVGA |
480(H)x272(V) pixel |
4.0” , 4.3” |
‧ VGA: |
640(H)x480(V) pixel |
5.6” , 5.7” , 10.4” |
‧ WVGA: |
800(H)x480(V) pixel |
5.0” , 7.0” , 10.2” |
‧ SVGA: |
800(H)x600(V) pixel |
7.0” , 8.0” , 10.4” |
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What is LCD response time? |
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Response time is the amount of time a pixel in a LCD takes to go from black to white and back to black again. It is measured in milliseconds (ms). Smaller values represent faster transitions and therefore smoother images. |
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What do the RGB bits represent? |
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There are three colors, red, green and blue, in a pixel. The changes of the saturation level of each color combine into a spectrum of colors. The saturation level can be represented by bit. The number of bits represents the power to 2. For example, if there are 8 bits for red, then there are 256 levels of saturation. Therefore, when we have 24 bits in a LCD module for color representations, 8 bits are equally divided to red, green and blue. In this way, there can be 16.8 millions colors. |
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What is TFT? |
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TFT-LCD stands for thin-film transistor liquid-crystal display.
It uses liquid crystal between to glass substrates to control the passage of light. The color filter is on the front glass substrate, and the back glass substrate has transistors on it. When voltage is applied, the liquid crystal is bent and a pixel is formed by the light that passes through. The color filter on the front glass substrate gives each pixel its own color. The combination of these pixels in different colors forms the image on the panel. |
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In-plane switching (IPS) |
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In-plane switching was developed by Hitachi Ltd. in 1996 to improve on the poor viewing angle and the poor color reproduction of TN panels at that time. Its name comes from the main difference from TN panels, that the crystal molecules move parallel to the panel plane instead of perpendicular to it. This change reduces the amount of light scattering in the matrix, which gives IPS its characteristic wide viewing angles and good color reproduction. |
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Multi-domain vertical alignment (MVA) |
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Multi-domain vertical alignment was originally developed in 1998 by Fujitsu as a compromise between TN and IPS. It achieved pixel response which was fast for its time, wide viewing angles, and high contrast at the cost of brightness and color reproduction. Modern MVA panels can offer wide viewing angles (second only to S-IPS technology), good black depth, good color reproduction and depth, and fast response times due to the use of Response Time Compensation technologies. When MVA panels are viewed off-perpendicular, colors will shift, but much less than for TN panels. |
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OLED |
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OLED stands for Organic Light Emitting Diode.
It is a light-emitting diode (LED) whose emissive electroluminescent layer is composed of a film of organic compounds that emit light when an electric current passes through it. This layer of organic semiconductor material is formed between two electrodes, where at least one of the electrodes is transparent. |
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