What is the 600Hz Sub-Field Drive Feature on Plasma Televisions? What is Hz Rate?
Also called 600Hz Subfield Motion
By Phil Conner
When LED televisions started to increase the Hz rate speed from 60Hz to 120Hz to 240Hz, plasma manufacturers needed a measurement to combat or compare plasma technology with LED technology. Hz is the number of cycles of a waveform per second. Hz rate in televisions - also called the refresh rate, determines how many times the screen is redrawn per second. In the U.S. The power mains run on a 60Hz cycle which explains why our televisions are 60Hz.
LCD and LED TVs there has always been an issue with motion lag, and especially jerky effects (also called "judder") from images when panning slowly from side to side. This is due to the difficulty these TVs have in properly displaying moving images. Fast moving images present particular problems as the twisting crystals on an LCD television have a hard time keeping up with the speed of the action sequence. So in effect, you are seeing distortions from the processing of the TV.
Lately, LED televisions have devised ways to increase the Hz rate in order to present a smoother picture during panning side to side motion and fast movement. The higher Hz rates enable the LCD panel (for both LCD and LED TVs) to process (via faster twisting crystals) the picture signal at a faster rate. Some specifications from these manufacturers are as high as 480 virtual Hz rate – doubling the 240 which doubled the 120 which doubled the 60.
Plasma manufacturers needed a response to this specification. Plasma Televisions have always been superior in the motion lag fast action scenes category due to the nature of plasma technology. There are no twisting crystals but instead pixels composed of 3 phosphor colors which each have their own electrode affixed to the back. These charges are extremely fast. So Panasonic and then the other plasma manufacturers found a way to measure the processing speed and came up with the term Subfield Drive or Sub-field Motion as a way to describe it. It describes a comparable speed for Plasma TVs of 600Hz or the image flashing 600 times per second to redraw the image.
The benefits of faster processing are smoother side to side panning, no motion lag in fast moving scenes, crisper and clearer images, smoother contouring transitions, and cleaner image edges. All of these benefits were already there in plasma televisions before the 600Hz relative specification was invented – they just did not have a name for it. Now these manufacturers are looking for ways to better even this specification.