Sunday, February 25, 2007

REFRESH RATE & RESPONSE TIME

Refresh Rate: The refresh rate is the number of times a display's image is repainted or refreshed per second. The refresh rate is expressed in "Hertz." A refresh rate of 75 means the image is refreshed or "redrawn" 75 times in a second. Acceptable refresh rates for the human eye is anything over 70hz. Refresh rates pertain mostly to Plasma and CRT Tube tv's. Low refresh rates result in on-screen flicker, which can make the eye tired as the screen isn't refreshing fast enough for the human eye.

Response Time: While a CRT Tube "repaints" the picture on the entire screen, LCD's work differently. Unlike a tube, LCD's are digital in nature and pixel based. The "response time" pertains to the time it takes for an LCD to make a pixel go from active (black) to inactive (white) and back to active (black) again. It is measured in milliseconds (ms). The faster the response time, the better. Failure to do this efficiently can cause smearing or ghosting where the image of a previously displayed screen image is still on the screen after a new image is displayed. LCD's are getting progressively better at this, while 8-12ms is more common, response times have gotten as fast as 6ms with some of Sharps, Aquos line of LCD's.

1 Comment:

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