### TL;DR -

* Was the LCD technology in Game & Watch passive (or active)?
* If so, was the technology used Twisted Nematics (and at which point, if at all, were Super Twisted Nematics employed, and in which latter models)?

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Leading on from [Thomas's excellent answer](https://retrocomputing.stackexchange.com/questions/1613/main-board-of-the-original-game-watch-ball#answer-1911) to the question, [Main board of the original Game & Watch (Ball)](https://retrocomputing.stackexchange.com/questions/1613/main-board-of-the-original-game-watch-ball), does anyone know what sort of LCD technology was used in the Game and Watch devices?

Thomas mentions that the LCD required constant refreshing (specifically for [Green House](https://en.wikipedia.org/wiki/List_of_Game_%26_Watch_games#Green_House), which came out in late 1982):

> 
> There is a bit more logic to it, but that's essentially it; some of the logic is to drive the screen; I don't remember the reason but I was explained that LCD screens from that era needed the segments to be toggled on / off to prevent some damage, apparently it's the same in watches; if anyone worked with that technology, I'd be happy to understand the details.
> 
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> 

I wondered what the answer was to the need for constant toggling, and decided to research the topic.

The [Wikipedia G&W - Models](https://en.wikipedia.org/wiki/List_of_Game_%26_Watch_games#Models) section lists the release dates which range from 1980 to 1991. Bearing that in mind, I looked up which LCD technologies were available at these dates.

The Wikipedia entry for the [history of the LCD during the 1970s and 80s](https://en.wikipedia.org/wiki/Liquid-crystal_display#1970s-1980s), states that [Twisted Nematic](https://en.wikipedia.org/wiki/Twisted_nematic_field_effect) (**TN**) field effect LCDs were available when the G&W was first conceived. Later, in 1983, [Super-Twisted Nematic](https://en.wikipedia.org/wiki/Super-twisted_nematic_display) (**STN**) structure for passive matrix addressed LCDs was invented, and so would have been available for the later models of G&W.

Assuming that the TN was used, en lieu of the earlier [Dynamic Scattering Mode](https://en.wikipedia.org/wiki/Dynamic_Scattering_Mode) (**DSM**) LCD (which was discovered in the [60s](https://en.wikipedia.org/wiki/Liquid-crystal_display#1880s-1960s)):

> 
> In 1971 the company of Fergason ILIXCO (now LXD Incorporated) produced the first LCDs based on the TN-effect, which soon superseded the poor-quality DSM types due to improvements of lower operating voltages and lower power consumption.
> 
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Presumably the LCD used was passive and not active. From [Passive and Active-matrix](https://en.wikipedia.org/wiki/Liquid-crystal_display#Passive_and_active-matrix), it is stated that STN requires constant refreshing, similar to that alluded to by Thomas in the quote above:

> 
> STN LCDs have to be continuously refreshed by alternating pulsed voltages of one polarity during one frame and pulses of opposite polarity during the next frame.
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> 
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The earlier TN also requires refreshing, or toggling, see the description of [Twisted Nematics](https://en.wikipedia.org/wiki/Twisted_nematic_field_effect#Description). Although in this wiki entry, there is no mention of refreshing, or field reversal, it *is* actually required1:

> 
> A voltage of about 1 V is required to make the crystal align itself with the field, and no current passes through the crystal itself. Thus the electrical power required for that action is very low.
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So, to summarise, are my assumptions correct, and TN was used in the earlier models of G&W? Also, was STN used in latter models? If so, at which point was STN employed and for which G&W models?

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From the article [Game & Watch](http://www.retrogamer.net/profiles/hardware/game-watch/) there are a number of references to the fact that when the G&W was designed LCD screens were crude, and with limited size/resolution yet cheap and plentiful, but the actual type of LCD used in not mentioned.

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1 The reason why polarity reversal is required is answered by [this answer](https://electronics.stackexchange.com/questions/276967/do-twisted-nematic-lcd-need-refresh-polarity-reversal/276973#276973) to the question [Do Twisted Nematic LCD need refresh (polarity reversal)?](https://electronics.stackexchange.com/questions/276967/do-twisted-nematic-lcd-need-refresh-polarity-reversal)