# Refresh Rate and LCD

**URL:** <https://psychtoolbox.discourse.group/t/refresh-rate-and-lcd/1488>\
**Category:** Uncategorized\
**Created:** [January 26, 2005, 11:38pm UTC](https://psychtoolbox.discourse.group/t/refresh-rate-and-lcd/1488 "2005-01-26T23:38:35Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![sandhitsu.rm](https://avatars.discourse-cdn.com/v4/letter/s/a88e57/32.png) [@sandhitsu.rm](https://psychtoolbox.discourse.group/u/sandhitsu.rm)\
**Post date:** [January 26, 2005, 11:38pm UTC](https://psychtoolbox.discourse.group/t/refresh-rate-and-lcd/1488/1 "2005-01-26T23:38:35Z")

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After reading through past messages, I realize that the response time for LCDs,  
which is equivalent to the refresh rate of CRTs, is generally slower than CRTs.   
In my tests with an animation loop, I get 60 Hz from the LCD.  
  
But since LCDs don't really scan, isn't there potentially a way to update the screen  
faster ? It seems like video cards still treat the output as going to a scanning device  
like CRT, and just assume a nominal framerate of 60 Hz if it's LCD and then there  
is a scan converter that actually refreshes the LCD screen. Can we trick the video  
hardware into putting out data at a faster rate to an LCD though ? Will it work ?   
Is there a way to do this on OS X ?  
  
How about syncing ? Does Flip automatically take care of that ?  
  
Sandhitsu

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**Author:** ![Allen\_Ingling](https://avatars.discourse-cdn.com/v4/letter/a/a183cd/32.png) [@Allen\_Ingling](https://psychtoolbox.discourse.group/u/Allen_Ingling)\
**Post date:** [January 27, 2005, 11:42am UTC](https://psychtoolbox.discourse.group/t/refresh-rate-and-lcd/1488/2 "2005-01-27T11:42:42Z")

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Dear Sandhitsu,  
  
The LCD monitors ARE slower. There's no scan (simultaneous refresh of  
all the pixels), and the pixels are able to change state separately,  
but the process (LC twist/untwist) is slow - 60Hz is the correct  
number.  
Maybe in the future they will improve, but the bottom line is - if you  
need a faster refresh rate, use CRTs.  
  
Yours -   
 Mark  
  
  

> On Wed, 26 Jan 2005 23:38:35 +0000, sandhitsu.rm \<[sudas@...](mailto:sudas@...)\> wrote:  
> \>   
> \> After reading through past messages, I realize that the response time for  
> \> LCDs,  
> \> which is equivalent to the refresh rate of CRTs, is generally slower than  
> \> CRTs.   
> \> In my tests with an animation loop, I get 60 Hz from the LCD.  
> \>   
> \> But since LCDs don't really scan, isn't there potentially a way to update  
> \> the screen  
> \> faster ? It seems like video cards still treat the output as going to a  
> \> scanning device  
> \> like CRT, and just assume a nominal framerate of 60 Hz if it's LCD and then  
> \> there  
> \> is a scan converter that actually refreshes the LCD screen. Can we trick the  
> \> video  
> \> hardware into putting out data at a faster rate to an LCD though ? Will it  
> \> work ?   
> \> Is there a way to do this on OS X ?  
> \>   
> \> How about syncing ? Does Flip automatically take care of that ?  
> \>   
> \> Sandhitsu  
> \>   
> \>   
> \>   
> \>   
> \>   
> \> Post your message to: [psychtoolbox@yahoogroups.com](mailto:psychtoolbox@yahoogroups.com)  
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> \> [http://psychtoolbox.org](http://psychtoolbox.org)  
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