120hz LED or 240hz LCD?

[Mark R]

Those numbers have nothing to do with refresh rates. Plasmas' refresh rates range from 48Hz to 96Hz. The numbers you are quoting are subfield drive numbers which were used as a marketing gimmick to compete with LCD's artificial refresh rates (120Hz-240Hz). They have nothing to do with refresh rates.

Th subfield rate may not equate to the frame refresh rate, but plasma screens by nature of the way they work must refresh the image (like a CRT, because each pixel is only illuminated briefly - although unlike a CRT, it is because plasma screens are digital devices; a plasma cell is either on, or it is off. The ratio of on-to-off time is what determines the apparent brightness).

In order to reduce perceived flicker, a subfield rate higher than the frame rate is required. In much the same way that cinema projectors use 48 or 72 Hz shutter rates, even though they only show 24 Hz material. A higher subfield rate also permits the use of 3D dithering techniques to further improve perceived contrast resolution.

The importance of 600 Hz subfield rate on plasma, is that this is the lowest subfield rate that permits integer scaling of all industry standard frame rates. Any screen with a lower subfield rate will have to resort to pulldown techniques with some material (e.g. a 480 Hz plasma will have to use pulldown for 50 Hz material, giving a juddering effect - although this should be minimally perceptible, unlike the very distracting 60 Hz 3:2 pulldown for 24 Hz material)

This hasn't stopped the marketing departments from blowing the importance and relevance of these subfield rates out of proportion.

 

[Oyeve]

I actually turn of trumotion and all that jazz as I hate how the screen looks. It looks fake to me. I actually prefer my 4 year old 32" 60hz 720p samsung TV to the newer one.

 

[JackBurton]

Th subfield rate may not equate to the frame refresh rate, but plasma screens by nature of the way they work must refresh the image (like a CRT, because each pixel is only illuminated briefly - although unlike a CRT, it is because plasma screens are digital devices; a plasma cell is either on, or it is off. The ratio of on-to-off time is what determines the apparent brightness).

In order to reduce perceived flicker, a subfield rate higher than the frame rate is required. In much the same way that cinema projectors use 48 or 72 Hz shutter rates, even though they only show 24 Hz material. A higher subfield rate also permits the use of 3D dithering techniques to further improve perceived contrast resolution.

The importance of 600 Hz subfield rate on plasma, is that this is the lowest subfield rate that permits integer scaling of all industry standard frame rates. Any screen with a lower subfield rate will have to resort to pulldown techniques with some material (e.g. a 480 Hz plasma will have to use pulldown for 50 Hz material, giving a juddering effect - although this should be minimally perceptible, unlike the very distracting 60 Hz 3:2 pulldown for 24 Hz material)

This hasn't stopped the marketing departments from blowing the importance and relevance of these subfield rates out of proportion.

It seems like you are still confusing subfield with refresh rate. The subfield has nothing to do with motion handling or judder. It is simply advertised for marketing purposes, nothing more. 60Hz refresh rate on a 480Hz subfield drive plasma will produce the same judder on 24 frame material as 60Hz refresh rate on a 600Hz subfield drive plasma.

For more information on subfield drive, here are a couple of links. The posts you want to read are from xrox.

http://www.avsforum.com/avs-vb/showthread.php?t=1047145

http://www.avsforum.com/avs-vb/showthread.php?t=1006091