Samsung 172X: 12ms Response Time for 17" LCD

Samsung LTM170EX

The cornerstone of any good LCD monitor is the panel. Samsung's 172X is no exception. We have talked about different display modes and LCD panels in the past. Today, we want to talk about a display mode that is traditionally different from Samsung's PVA (Pattern Vertical Alignment) display mode. We will talk about TN or twisted nematic mode.

If you have read our LCD primer, you may already be familiar with Twisted Nematic display modes, or other variations on TN, such as TN with some sort of Frame Rate Control. Sharp's LL-191A LCD uses a TN display mode, and we also explained that in the review.

In a nutshell, the problem with current LCD displays is that many of them cannot break the 25ms response time barrier. Response time has quickly become the most important specification when buying an LCD. In most cases, we call the "average" response time the time it takes a pixel to twist and untwist, also known as "time rising, time falling" (we abbreviate that as "TrTf"). As manufacturers approach the boundary of display technologies such as PVA, MVA and IPS, it appears the industry has come full circle; back to the original TN technology used in some of the first LCDs.

Here is the problem: as manufacturers continue to stretch the limitations of their slightly different twisting methods, they begin to hit the theoretical limit for how fast their twisting technology can work. Granted, each technology has advantages and disadvantages, particularly in the realm of viewing angle and color replication. Within the last year, however, AUO, LG Philips LCD, and now Samsung have all readopted the TN technology with some minor tweaks.

Just like the Hitachi CML174 and the Sharp LL-191A, the Samsung 172X uses a 6-bit LCD panel. Our particular SyncMaster 172X uses the Samsung LTM170EX, one of Samsung's newest panels not even listed directly on the website. You can find out more information through a Samsung Semiconductor brochure. Notice that the monitor claims 16.2M color replication - a 6-bit LCD with a dithering technology. In reality, this LCD can only produce 262,000 color shades, but by using a method of frame rate control, the panel controller can adjust voltages to emulate out of bound gray scales.

Aside from the 6-bit display, most things concerning the LTM170EX are quite outstanding. The 500:1 contrast ratio seems about right for a TN based display. Our monitor produces 270 cd/m² brightness; although, we suspect the European version may actually produce 300cd/m². Last, but not least, the response time claims an impressive sub-13ms response time. There is a small footnote stating that these results are measured at 25 degrees Celsius (77 degrees Fahrenheit). We suspect that the transition periods may be higher at lower temperatures, since the liquid crystals are at a slightly higher state of solidity.