LCD vs DLP replonse time

[tausifs]

Hi,

is there any difference between LCD pixel response time and that of 'mirror' response time for DLP DMD, or can't the 2 be compared ?

Thanks,

tausif.

[Avi]

Originally Posted by tausifs

Hi,

is there any difference between LCD pixel response time and that of 'mirror' response time for DLP DMD, or can't the 2 be compared ?

Thanks,

tausif.

tausifs

Yes there is a difference in the time taken to fully change state. I'm not sure what is meant by "reponse time" but LCOS is around 4ms or a bit less. DLP is generally quoted as being around 500 times faster for full state change. The mirror is in a constant state of dither and one of the side effects of this can be visible dither (green pixelation) noticeable in dark scenes. This tends to be less of a problem or a complete non issue on some of the lastest DLP PJ's. Also it appears different DMD versions use different mirror drivers and according to reports some handle motion better than others.

LCD, LCOS and DLP do have a different image style in a similar way to LCD and plasma displays. Some claim the sample and hold effect of LCD and LCOS causes the perception of motion smear/blur and this may contribute more to the issue rather than just response time.

AVI

[tausifs]

Is there no lens shift with DLP ?

The HD80 for example has vertical adjust but is this achieved by lens shift or keystone ?

[Colin151]

Hi again Taufis,
Yes most DLP's don't have mechanical lens shift (the older H79 I just bought has mechanical vertical lens shift actually, - very useful,) Why this is I don't know. I also don't know why the zoom range is always limited compared to LCD too?? Anyone any ideas?

I think I can notice the "Smear" effect with LCD. As you know a liquid crystal is a chemical and it works by voltages that change the temperature over the liquid crystal (different colours are produced according to the temperature) so I think there is always a lag time as a lot depends on how quickly the chemical changes/responds. DLP looks far better to my eyes, - they talk about motion blur on the Texas insturments DLP site, - have a look at this page.
http://www.dlp.com/hdtv/no_motion_blur.aspx


As for the green pixellation I have not seen that with my current H79 or the HD65 I had before.

Cheers,
Colin

Originally Posted by tausifs

Is there no lens shift with DLP ?

The HD80 for example has vertical adjust but is this achieved by lens shift or keystone ?

[Avi]

Originally Posted by tausifs

Is there no lens shift with DLP ?

The HD80 for example has vertical adjust but is this achieved by lens shift or keystone ?

Lens shift/zoom varies by product. My understanding is that due to the technical properties of DLP it is more costly to achieve good results. Hence, as a rule of thumb optical shift and bigger zoom range often only appears on more expensive products. Optical shift can be helpful if you have a difficult install. The downside is the greater the shift range the greater the potential of PQ issues i.e. CA, focus etc unless expensive glass is used. Some products provide options for specific zoom range lenses as opposed to a one size fits all due to the expense of the glass for a single high quality lens solution.

AVI

[Colin151]

Hi Tausfs,
If you are to buy a ceiling mount then the you can get one that is adjustable in all directions so you can point it down more if you wish, - the H79 ceiling mount I got with the H79 is like this, - really easy to get the pic set up to the screen, - I don't even have to use the mechanical vertical lens shift like this. So there are ways around the mechanical lens shift problem with DLPs.

Cheers,
Colin

[Avi]

Originally Posted by Colin151

I think I can notice the "Smear" effect with LCD. As you know a liquid crystal is a chemical and it works by voltages that change the temperature over the liquid crystal (different colours are produced according to the temperature) so I think there is always a lag time as a lot depends on how quickly the chemical changes/responds. DLP looks far better to my eyes, - they talk about motion blur on the Texas insturments DLP site, - have a look at this page.
http://www.dlp.com/hdtv/no_motion_blur.aspx

Whilst this may contribute I think the main issue is how LCD holds the image until it changes as opposed to contstant change. Because of the sample and hold our brains percieve smear when a change occures. Some of the new products use black frame insertion to help reduce the perception of this effect. Much of the info I've read from TI about it's competitors is often based on old technology. Do they still use the DLP v LCD high usage report they comissioned in 2002/2003 ?

AVI

[Colin151]

Hi Avi,
Yes you are right LCD tecnology has improved massively in terms of the smear, - better/improved liquid crystal chemicals etc. we have an old LCD TV at work here that has a massive smear effect! And yes Texas probably still use the 2002 report no doubt!

I had the Panny AX200E LCD and now have an Optoma H79 DLP. Though the Panny was OK in terms of smear there is something that looks much better about the H79 DLP pic on moving stuff, - it is really noticable with PS3 computer games despite the AX200E having that "gaming" mode with improved response, - the DLP pic looks less smeary to my eyes.

Cheers,
Colin

[Avi]

Originally Posted by Colin151

Hi Avi,
Yes you are right LCD tecnology has improved massively in terms of the smear, - better/improved liquid crystal chemicals etc. we have an old LCD TV at work here that has a massive smear effect! And yes Texas probably still use the 2002 report no doubt!

I had the Panny AX200E LCD and now have an Optoma H7 DLP. Though the Panny was OK in terms of smear there is something that looks much better about the H79 DLP pic on moving stuff, - it is really noticable with PS3 computer games despite the AX200E having that "gaming" mode with improved response, - the DLP pic looks less smeary to my eyes.

Cheers,
Colin

Hi Colin

I don't have an LCD but I use both a D-ILA and DLP pj. As you say there are differences that are more noticeable when you see the images side by side.

AVI

[tausifs]

And how are DLPs with regard to the screen door/ chicken wire effect ?

[Colin151]

Hi Taufis,
There are pixels with DLP but it is well known that there in no screendoor/chickenwire effect with DLP, - that is something charateristic of LCD technology only. You can therefore sit closer to the screen with DLP and not get this nasty effect (however you might see the Rainbow effect more when you sit closer though! (and that could possibly be a problem depending on how sensitive you are to it!!))

I know the Panny has that smooth screen technology that vitually banishes the screendoor effect but I think it really effects the image sharpness and makes it look too soft, - I note that in one of those online reviews of the AX200 (or maybe it was the AX100?!) someone mentions this as well (will look it up for you).

Cheers,
Will be really interested to know what you think of the DLP pic when you view the HD80!,
Colin

[Colin151]

Hi AVI,
Yes I suppose the differences would if you were viewing side by side, but I wasn't, - this was on separate occasions. I was not directly comparing two PJ's. Maybe it is becuase I am just more sensitive to the shortcomings of the LCD pic than others?!!

The D-ILA is supposed to be very good isn't it?, - sort of like the best of both technologies.

Cheers,
Colin

Originally Posted by Avi

Hi Colin

I don't have an LCD but I use both a D-ILA and DLP pj. As you say there are differences that are more noticeable when you see the images side by side.

AVI

[Avi]

Originally Posted by Colin151

The D-ILA is supposed to be very good isn't it?, - sort of like the best of both technologies.

Both D-ILA and DLP have areas of general strength and weakness as technogies. D-ILA's high native full field contrast improves performance in low APL (darker) scenes but it can look less dimensional and hazy in higher APL (brighter) senes. The reverse is true of DLP in low APL scenes but it looks better to my eyes in higher APL scenes. Some of the lastest DLP products also offer higher full field contrast so you can get the best of both worlds. The pixel structure of DLP appears more delineated than D-ILA and I think this adds to the perception of a crisper image. Certainly at 1080 resolution there is no visible pixel structure with either unless you are very, very close to the screen.

AVI

[Colin151]

Hey Taufis,
That thing I read about smoothscreen technology giving a soft pic was actually someone talking about the AE2000E. Have a read. here is the link: -

Panasonic PT-AE2000 Launch Event AV Forums Special Report

Cheers,
Colin

Originally Posted by Colin151

I know the Panny has that smooth screen technology that vitually banishes the screendoor effect but I think it really effects the image sharpness and makes it look too soft, - I note that in one of those online reviews of the AX200 (or maybe it was the AX100?!) someone mentions this as well (will look it up for you).

Colin

[Colin151]

Cheers for that interesting info,
Yes I agree DLP does give a really nice crisp pic that I love. It looks a lot sharper/crisper than the Panny AX200E LCD projector I had. And I agree you cannot see the pixel structure of a DLP projector unless you are very very close to the screen (like virtually put you head close to it!)

I assume you have a JVC D-ILA. I'm very interested to know what DLP projector do you have? Is it a 1080p native model?

Cheers again,
Colin

Originally Posted by Avi

Both D-ILA and DLP have areas of general strength and weakness as technogies. D-ILA's high native full field contrast improves performance in low APL (darker) scenes but it can look less dimensional and hazy in higher APL (brighter) senes. The reverse is true of DLP in low APL scenes but it looks better to my eyes in higher APL scenes. Some of the lastest DLP products also offer higher full field contrast so you can get the best of both worlds. The pixel structure of DLP appears more delineated than D-ILA and I think this adds to the perception of a crisper image. Certainly at 1080 resolution there is no visible pixel structure with either unless you are very, very close to the screen.

AVI