Dead Pixels in LCD Displays at DVinfo.net

Jack Robertson · July 28th, 2003, 08:19 PM

Hello all,

I don’t have a real reason to post this, but since there was someone who asked and is a common problem among LCD screens that affect Cameras as well, here is a little reply post I did in another forum…

Subject:
Dead Pixels in LCD Displays

I bought a new XM2 and as soon I unpacked it I noticed three dead pixels...( I wasn't very happy), but I rang the dealer who sold it to me and he organised a replacement from Canon... no questions asked!

Some manufacturers see “Dead Pixels” differently (mainly with LCD displays), they claim the error rate accounts for some dead pixels and have all different policies regarding them. But they all insist on claiming that you are getting a 1600x1200 pixel monitor (for example), which to me is not true even if only one pixel is dead! So technically they have to replace it and give you a monitor that has the full advertised 1600x1200 pixels all working... right?

In retrospect, does one buy a car with a dead wheel and accepts it? Highly unlikely!

The XM2 is not a toy and thus should be perfect when new... it is (in my opinion) seldom for the camera to create dead pixels after purchasing the camera WITHOUT any dead pixels... it either has or hasn't got dead pixels when manufactured.

I will however point out that a dead pixel is much better than one stuck on a colour especially RED! That is what happened with me... One bright Red pixel, one bright Green pixel and one dead pixel (unlit).

Here is an interesting article about dead pixels in LCD screens if you are interested.

http://www4.tomshardware.com/display/20030319/

Also, one way to test for dead pixels is to generate a few different colours and feed them into the camera (via SD memory card) or shoot them via the lens to see individual pixels if they are dead or permanently lit.

Cheers,
Jack – XM2 User

Gints Klimanis · July 28th, 2003, 08:50 PM

>In retrospect, does one buy a car with a dead wheel and >accepts it? Highly unlikely!

That's a bit of an overstatement. Even with cars, you are buying
a particular range of "defects" in the form of manufacturing tolerances. Car manufacturers screen for defects that fall outside of the designed limits. Your new car is not perfect, either.
A dead wheel is a critical defect. A scratch on the chassis will go unnoticed. Likewise, a dead pixel is not a critical defect in the minds of most consumers.

As for LCD panels, it's pretty clear that the market is willing to
accept a particular # of defects although it seems that the manufacturers are trying increase this #. I didn't want to bother returning my first JVC camcorder with one dead pixel in the LCD display for two reasons: 1) it didn't really bother me 2) I know products are shipped with dead pixels and thought the next unit could be the same or worse.

LCD panel manufacturers can ship all of their panels with zero dead pixels, but you will be paying more.
It's clear the manufaturers are trying to reduce their cost of shipping LCD products by shipping slightly defective panels.

Jack Robertson · July 28th, 2003, 10:25 PM

Gints,

I agree with you, that zero dead pixels would cost us more, but in the end it comes down to what the customer is willing to accept.

As you have mentioned it really didn't bother you having one dead pixel, but if you had the problem I had, you might have had a different view.... One Pixel stuck on RED, One Pixel Stuck on Green and one dead... as I said previousy, a dead pixel is better than one stuck on a colour, which is far more annoying and always in your face!

Jack

Gints Klimanis · July 29th, 2003, 01:08 AM

Jack,

I'm with you on dead pixels, be they unlit or "stuck". For my first sub $1000 camcorder with a 3.5" flipout LCD, I didn't care. I would have been more upset if my Sony vx-2000 with it's 2.5" flip LCD had a dead pixel, but I still would have accepted it. On an LCD display or TV, I would have less tolerance.

The higher the price, the lower my tolerance. Manufacturers should know this, but obviously, consumers are accepting it.
I've seen $5000 rear projection Tvs with dead pixels on pretty small LCDs. What's up with that? If the return rate were significant, manufacturers would ship with dead pixel ratings and possibly offer discounts that reflect quality of the LCD shipped.
For camcorders, the manufacturers should make it easy for the user to remove and replace the LCD.

Don Palomaki · July 29th, 2003, 04:28 AM

The cost of using only perfect LCD (or CCD for that matter) would be prohibitive for most users of these consumer/prosumer/entry-level progessional camcorders.

It goes back to the attainable yield in the semiconductor manufacturing process. A For a perfect CCD you would have to produce a chip with 270,000 or more perfect transistors.

Will Fastie · July 29th, 2003, 07:46 AM

The yield of perfect 3" and under flat displays is quite high today. Yield is the major factor that prevents or allows a manufacturer to move along to larger sizes. There was a time when the cost of a 3" display was prohibitive because of yield, but those days are long gone.

That doesn't mean less than perfect ones won't show up, but I see no reason not to demand a perfect one.

I don't know what the yield equation is for CCDs. The yield for semiconductor devices in these sizes is pretty high, though.

Will

Chris Hurd · August 1st, 2003, 12:27 PM

Like most other camera manufacturers, Canon provides a gaurantee of 99.97% on the LCD pixels. This means that there might be 3 or 4 dead or hot pixels. Since they're in the LCD display and not in the CCD block, image quality is NOT affected. As inexpensive as this gear is these days, in my opinion a 0.03% tolerance is more than acceptable. If you need 100% firing pixels in the LCD display, you can have them, but they will be in a significantly costlier camcorder than the GL2 or XM2. Hope this helps,

Will Fastie · August 1st, 2003, 12:43 PM

Chris, you're right, I wasn't clear. I agree that LCD quality is not a determining factor for camcorders, as it won't affect the camcorder's output. LCD quality on a laptop PC is a determining factor; I, for one, demand that all the pixels work.

The question is whether it is reasonable to expect a CCD to be perfect. The CCD will affect output, so I say it must be perfect. Is it reasonable to make that demand? I think it is because the yield for semiconducter devices sized like CCDs and with similar component counts is extremely high today.

As for getting 270,000 perfect transistors, contemporary CPU chips have millions of transistors. While it might be okay for memory to have defective transistors that can be avoided by using spares, the core circuitry of a processor is either right or wrong. Most CPUs come off the line right; processor yields today are high.

Will

Phil Christopher · August 20th, 2003, 05:53 AM

Hi all!

I'm new - so after having used this site as a fantastic reference help before buying my XM2 this is my first post!

Got my XM2 (new) last night so haven't had a chance to check it totally although I can already see a stuck/hot pixel (red) just off the centre of the LCD display.

I have read the links to dead/stuck pixel related stuff on this post and elsewhere and I think this is a plain scary situation from the end-user point of view. I understand the argument that imperfect screens still need to be used/sold in the marketplace and there is a place for them, however I feel the heart of the matter is this: regardless of the cost a product containing an LCD screen should be perfect unless info regarding this problem (not uncommon it seems) is freely available from manufacturer to customer prior to purchase.

Most manufacturers do not seem to make this info easily accessible - understandably possible defects are not a great selling point - and after having no luck with documentation or online, currently Canon UK (who told me 99.99% - I haven't done the maths yet) are trying to source something that is actually written down to send me regarding this subject.

I am just coming from the consumer info angle because, like many of us I'm sure, I have had a fair amount of use of LCD screens for quite a while now on computers, cameras and the like and although I have seen this problem before on stuff I don't own, I have never entertained the idea that visible LCD defects would be tolerated in a brand new product.

Don't know about the truth in this, however the idea that Philips are using/will use zero tolerance of dead pixels in screens as a selling point is laudable and seems like a more positive manufacturer response.

I read with glee the advice on one of the posts regarding 'stuck' pixels - on solidly red, green or blue - and the fact they might be gently 'massaged' back to functioning normally using a lens cloth or similar. I love this cam already and can't wait to get home from work to try that - although I might refrain from telling my friends...!

Phil Christopher · August 21st, 2003, 05:10 AM

Just to update - tried the 'pixel massage' theory, but no joy. Worth a shot I suppose...

Phil

July 28th, 2003, 08:19 PM	#1
Jack Robertson Regular Crew Join Date: Jun 2003 Location: Sydney, Australia Posts: 125	Dead Pixels in LCD Displays Hello all, I don’t have a real reason to post this, but since there was someone who asked and is a common problem among LCD screens that affect Cameras as well, here is a little reply post I did in another forum… Subject: Dead Pixels in LCD Displays I bought a new XM2 and as soon I unpacked it I noticed three dead pixels...( I wasn't very happy), but I rang the dealer who sold it to me and he organised a replacement from Canon... no questions asked! Some manufacturers see “Dead Pixels” differently (mainly with LCD displays), they claim the error rate accounts for some dead pixels and have all different policies regarding them. But they all insist on claiming that you are getting a 1600x1200 pixel monitor (for example), which to me is not true even if only one pixel is dead! So technically they have to replace it and give you a monitor that has the full advertised 1600x1200 pixels all working... right? In retrospect, does one buy a car with a dead wheel and accepts it? Highly unlikely! The XM2 is not a toy and thus should be perfect when new... it is (in my opinion) seldom for the camera to create dead pixels after purchasing the camera WITHOUT any dead pixels... it either has or hasn't got dead pixels when manufactured. I will however point out that a dead pixel is much better than one stuck on a colour especially RED! That is what happened with me... One bright Red pixel, one bright Green pixel and one dead pixel (unlit). Here is an interesting article about dead pixels in LCD screens if you are interested. http://www4.tomshardware.com/display/20030319/ Also, one way to test for dead pixels is to generate a few different colours and feed them into the camera (via SD memory card) or shoot them via the lens to see individual pixels if they are dead or permanently lit. Cheers, Jack – XM2 User

July 29th, 2003, 04:28 AM	#5
Don Palomaki Wrangler Join Date: Sep 2001 Location: Northern VA Posts: 4,489	The cost of using only perfect LCD (or CCD for that matter) would be prohibitive for most users of these consumer/prosumer/entry-level progessional camcorders. It goes back to the attainable yield in the semiconductor manufacturing process. A For a perfect CCD you would have to produce a chip with 270,000 or more perfect transistors. __________________ dpalomaki@dspalomaki.com

August 1st, 2003, 12:27 PM	#7
Chris Hurd Obstreperous Rex Join Date: Jan 2001 Location: San Marcos, TX Posts: 27,368 Images: 513	Like most other camera manufacturers, Canon provides a gaurantee of 99.97% on the LCD pixels. This means that there might be 3 or 4 dead or hot pixels. Since they're in the LCD display and not in the CCD block, image quality is NOT affected. As inexpensive as this gear is these days, in my opinion a 0.03% tolerance is more than acceptable. If you need 100% firing pixels in the LCD display, you can have them, but they will be in a significantly costlier camcorder than the GL2 or XM2. Hope this helps, __________________ CH Search DV Info Net \| 20 years of DVi \| ...Tuesday is Soylent Green Day!

July 28th, 2003, 08:50 PM	#2
Gints Klimanis Inner Circle Join Date: Jun 2003 Location: San Jose, CA Posts: 2,222	>In retrospect, does one buy a car with a dead wheel and >accepts it? Highly unlikely! That's a bit of an overstatement. Even with cars, you are buying a particular range of "defects" in the form of manufacturing tolerances. Car manufacturers screen for defects that fall outside of the designed limits. Your new car is not perfect, either. A dead wheel is a critical defect. A scratch on the chassis will go unnoticed. Likewise, a dead pixel is not a critical defect in the minds of most consumers. As for LCD panels, it's pretty clear that the market is willing to accept a particular # of defects although it seems that the manufacturers are trying increase this #. I didn't want to bother returning my first JVC camcorder with one dead pixel in the LCD display for two reasons: 1) it didn't really bother me 2) I know products are shipped with dead pixels and thought the next unit could be the same or worse. LCD panel manufacturers can ship all of their panels with zero dead pixels, but you will be paying more. It's clear the manufaturers are trying to reduce their cost of shipping LCD products by shipping slightly defective panels.

July 28th, 2003, 10:25 PM	#3
Jack Robertson Regular Crew Join Date: Jun 2003 Location: Sydney, Australia Posts: 125	Gints, I agree with you, that zero dead pixels would cost us more, but in the end it comes down to what the customer is willing to accept. As you have mentioned it really didn't bother you having one dead pixel, but if you had the problem I had, you might have had a different view.... One Pixel stuck on RED, One Pixel Stuck on Green and one dead... as I said previousy, a dead pixel is better than one stuck on a colour, which is far more annoying and always in your face! Jack

July 29th, 2003, 01:08 AM	#4
Gints Klimanis Inner Circle Join Date: Jun 2003 Location: San Jose, CA Posts: 2,222	Jack, I'm with you on dead pixels, be they unlit or "stuck". For my first sub $1000 camcorder with a 3.5" flipout LCD, I didn't care. I would have been more upset if my Sony vx-2000 with it's 2.5" flip LCD had a dead pixel, but I still would have accepted it. On an LCD display or TV, I would have less tolerance. The higher the price, the lower my tolerance. Manufacturers should know this, but obviously, consumers are accepting it. I've seen $5000 rear projection Tvs with dead pixels on pretty small LCDs. What's up with that? If the return rate were significant, manufacturers would ship with dead pixel ratings and possibly offer discounts that reflect quality of the LCD shipped. For camcorders, the manufacturers should make it easy for the user to remove and replace the LCD.

July 29th, 2003, 07:46 AM	#6
Will Fastie Major Player Join Date: Feb 2003 Location: Jarrettsville, MD Posts: 353	The yield of perfect 3" and under flat displays is quite high today. Yield is the major factor that prevents or allows a manufacturer to move along to larger sizes. There was a time when the cost of a 3" display was prohibitive because of yield, but those days are long gone. That doesn't mean less than perfect ones won't show up, but I see no reason not to demand a perfect one. I don't know what the yield equation is for CCDs. The yield for semiconductor devices in these sizes is pretty high, though. Will

August 1st, 2003, 12:43 PM	#8
Will Fastie Major Player Join Date: Feb 2003 Location: Jarrettsville, MD Posts: 353	Chris, you're right, I wasn't clear. I agree that LCD quality is not a determining factor for camcorders, as it won't affect the camcorder's output. LCD quality on a laptop PC is a determining factor; I, for one, demand that all the pixels work. The question is whether it is reasonable to expect a CCD to be perfect. The CCD will affect output, so I say it must be perfect. Is it reasonable to make that demand? I think it is because the yield for semiconducter devices sized like CCDs and with similar component counts is extremely high today. As for getting 270,000 perfect transistors, contemporary CPU chips have millions of transistors. While it might be okay for memory to have defective transistors that can be avoided by using spares, the core circuitry of a processor is either right or wrong. Most CPUs come off the line right; processor yields today are high. Will

August 20th, 2003, 05:53 AM	#9
Phil Christopher New Boot Join Date: Aug 2003 Location: Dorset, UK Posts: 10	Hi all! I'm new - so after having used this site as a fantastic reference help before buying my XM2 this is my first post! Got my XM2 (new) last night so haven't had a chance to check it totally although I can already see a stuck/hot pixel (red) just off the centre of the LCD display. I have read the links to dead/stuck pixel related stuff on this post and elsewhere and I think this is a plain scary situation from the end-user point of view. I understand the argument that imperfect screens still need to be used/sold in the marketplace and there is a place for them, however I feel the heart of the matter is this: regardless of the cost a product containing an LCD screen should be perfect unless info regarding this problem (not uncommon it seems) is freely available from manufacturer to customer prior to purchase. Most manufacturers do not seem to make this info easily accessible - understandably possible defects are not a great selling point - and after having no luck with documentation or online, currently Canon UK (who told me 99.99% - I haven't done the maths yet) are trying to source something that is actually written down to send me regarding this subject. I am just coming from the consumer info angle because, like many of us I'm sure, I have had a fair amount of use of LCD screens for quite a while now on computers, cameras and the like and although I have seen this problem before on stuff I don't own, I have never entertained the idea that visible LCD defects would be tolerated in a brand new product. Don't know about the truth in this, however the idea that Philips are using/will use zero tolerance of dead pixels in screens as a selling point is laudable and seems like a more positive manufacturer response. I read with glee the advice on one of the posts regarding 'stuck' pixels - on solidly red, green or blue - and the fact they might be gently 'massaged' back to functioning normally using a lens cloth or similar. I love this cam already and can't wait to get home from work to try that - although I might refrain from telling my friends...!

August 21st, 2003, 05:10 AM	#10
Phil Christopher New Boot Join Date: Aug 2003 Location: Dorset, UK Posts: 10	Just to update - tried the 'pixel massage' theory, but no joy. Worth a shot I suppose... Phil