Refresh Rates of PowerBook Displays

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By Ross Lodge

This article provides general information on display refresh rates used in Macintosh PowerBook computers. However, the information provided here should not be used to compare display to the built-in display of your PowerBook. It is impossible to compare Cathode Ray Tubes monitors (CRTs), used with desktop Macintosh computers, to passive and active matrix Liquid Crystal Display (LCD) screens, used in PowerBook computers, because CRTs and LCDs use entirely different technologies. There are two types of LCD displays using different technologies to create the image on the screen.

Active Matrix

Active matrix displays, also called Thin-Film Transistor (TFT), have transistors that are individually addressed and charged. The amount of time that it takes for the charge to diminish is around 20 milliseconds (ms). Apple uses a refresh rate of 62Hz on all (color and grayscale) TFT displays which means that each row of pixels gets refreshed every 16ms.

Passive Matrix

Passive matrix displays, also called Film SuperTwisted Nematic (FSTN), have a faster refresh rate. Once their pixels receive a charge, the time it takes for the pixel to lose its charge can be measured in seconds. In fact, the fastest time that the computer can turn a pixel off is over 60ms. The passive matrix screens use a refresh rate of 73Hz for grayscale passive matrix (MFSTN) displays and 79Hz for color passive matrix (CFSTN) displays, each row of pixels is refreshed every 12ms.

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