SID’s 50th Anniversary – Then & Now

This past weekend marked a milestone for the electronic display industry, the 50th anniversary of the Society for Information Display (SID) which was celebrated at its birthplace, Boelter Hall at UCLA.  SID is the preeminent organization serving the display industry, sponsoring symposiums for display technology and display business.  Several of those early contributors have passed away in recent years.  Looking back 50 years, the industry was still using Nixie tubes and was only developing commercial CRT displays.  I have a clear memory of my early days at Xerox R&D as a co-op student more than 40 years ago, asking my boss what the ideal display would look like.  With only a moment’s thought he pointed to a memo on his desk and said that it would look just like this – paper, but would be instantly reconfigurable.

While displays have come a long way they still do not look as good as paper.  Even though paper doesn’t emit one photon of light, nobody ever says that it doesn’t look bright enough or colorful enough or flexible enough or thin enough or low power enough or sufficiently viewable from all angles.  One has to wonder if in 50 years we will yet have a display with the attributes of paper.

I could never have imagined in those early years  that anyone would ever complain that a display was too colorful.  Yet, that is exactly the conclusion of Ray Soniera of DisplayMate.  http://bit.ly/PgmCFN  He says that the display in the Galaxy S3 is too colorful because it has a color gamut in excess of sRGB, a standard that was historically picked for studio monitors. The iPhone5 has an LCD that very closely matches sRGB, so presumably that make this better that the Galaxy S3 that has a gamut that is ~105% of 1953 NTSC

On the other hand, every TV showroom is filled with TVs that strive for 1953 NTSC color gamut, a gamut that is 41% larger than sRGB.  It was correctly noted by some bloggers that if one offered a TV with only sRGB consumers comparing TVs would be very unlikely to pick the sRGB model for their TV.  You need to be a judge of this attribute for yourself.  While sRGB has been the gamut standard for web content, smartphones are increasingly displaying video, where the standard has been NTSC.  There are those who now expect their smartphone to be able to display both video and web content with the color of the most demanding application.

At this link you can see a comparison of both NTSC and sRGB

http://bit.ly/WlChYr

 

When I have demonstrated my Galaxy S3, those people that I have polled have been very impressed with the color and the contrast.  None have said it has gaudy colors.

Ray also comments that the Galaxy S3 needs to be brighter.  On this point I might agree.  If you want to use the S3 in full sunlight it is difficult to compete with an LCD that is also partially transflective.  It takes considerable brightness to compete with the sun.  That said it is largely due to PenTile technology that the S3 display is as bright as it is.  Brightness correlates to current density.  Lifetime is affected by current density.  Thanks to PenTile which reduced current density, the S3 is still viewable in rather bright environments.

Neither the Galaxy S3 nor the iPhone 5 display are yet up to the standards of paper, but I must say that both of these displays have come a long way from where this industry began only 50 years ago.

 

 

PenTile Super AMOLED Chosen for Display Application Gold Award – 2nd Year in a Row

There is one organization that is more focused than any other on displays—the Society for Information Displays, now celebrating its 50 year anniversary.  Display Week is held each year as a gathering of the world’s display experts.  After evaluating every new display component that has been introduced into products this past year SID selected the display in the Samsung Galaxy Note for the gold award winner.  You might recall that the display in the Samsung Galaxy S won this award last year.  So, for two years in a row a PenTile OLED panel has been awarded this coveted honor.

http://www.androiddoes.net/breaking-news/galaxy-note-wins-display-industry-award-at-sid-2012/

Shown below is T K Lee of Samsung SMD accepting the award at SID’s awards luncheon event.

 

 

 

 

 

 

 

 

 

 

Here is a photo of the Galaxy Note Gold Award winner exhibit in the Samsung booth.

 

 

 

 

 

 

 

 

 

So if the world’s experts in displays, who also generated he first comprehensive standard for display metrology published May 31, 2012 have judged this PenTile display as the best how can it be that so many bloggers persist in finding fault with PenTile displays? It is time to recognize the impact that PenTile has had on the display industry and the quality that it offers.

Shown below is the Samsung SID booth.

Amongst the roughly 30+ displays that were shown this about one half of these were PenTile displays, including the PenTile Super AMOLED displays used in the Galaxy Note, the Galaxy Nexus, the Galaxy Prime, the Galaxy Nexus and the newly announced  Galaxy SIII smartphones.  Samsung also exhibited their line of mirrorless digital SLR cameras, each of which uses a 3-inch VGA PenTile OLED display.

Inventor of OLED – Professor Ching Tang

It is all too easy to forget where good ideas come from.  I wanted to pass along a link to an article in the Rochester Democrat and Chronicle talking about Professor Ching Tang the inventor of OLED technology, who in the 1980s was at Kodak, but is today a professor at the University of Rochester. http://on.rocne.ws/JTBLfT

Last year he was awarded the coveted Wolf Prize in chemistry.  I have to wonder if he ever imagined the impact his idea would have 30 years later.  Together with his colleague,  Steven Van Slyke, many patents were awarded for this technology.

Professor Ching Tang from Democrat and Chronicle

 

Why PenTile Technology Improve OLED Lifetime

Many bloggers have picked up on comments that Philip Berne of Samsung made at a recent press event.  He explained that the reason that Samsung chose PenTile Super AMOLED over RGB stripe AMOLED was that of lifetime, specifically that of blue subpixels.  He is exactly right, but let me explain this a little more.

AMOLEDs have lifetime that is related to the current density used to drive the OLED material.  This is especially true for blue since blue has the lowest brightness for a given amount of current.  The other way to say this is that blue OLED material has lower luminous efficiency.  To maintain the same brightness with blue, OLED display designers have to drive it with more current per unit area.

So how does PenTile technology help Samsung to extend lifetime for high resolution panels?

This comes from the ability to use 2/3s the number of subpixels in PenTile OLED (Super AMOLED)  relative to RGB stripe OLED (Super AMOLED Plus).  Thanks to PenTile technology’s use of subpixels rendering it is possible to have the same number of pixels as the equivalent RGB stripe.  With only 2/3s the subpixels, one can make the ratio of driven subpixel area larger with a smaller overall percentage of space in between subpixels (better fill factor), as compared to RGB stripe – which is what gives rise to the improvement in current density for a given brightness,  which in turn leads to better lifetime.

For lower pixel pitch, such as was used in the Galaxy S Plus, the current density was relatively low due to the coarser pixel pitch so the lifetime was fine.  But, at the pixel density of the Galaxy Nexus or the Galaxy S III, PenTile is the way to go, at least until sometime in the future when significant strides are made in blue OLED material luminous efficiency.  As I have said before, PenTile is an enabler that make high resolution OLED practical for the product brightness and lifetimes specs that we all have come to demand.   This is why you have never seen any production OLED  of greater than 250 dpi without a PenTile configuration.  If the demand for ever increasing pixel pitch continues, PenTile will still be key even if blue luminous efficiency sees some level of enhancement.

Galaxy S3 Arrives — and, yes, with PenTile Super AMOLED

Samsung Galaxy S3

At long last the long awaited Galaxy SIII smartphone has emerged and the blogs such as Android Community  http://bit.ly/K5t9Rz are describing the unboxing.  Despite the many speculations about Samsung abandoning PenTile for this 720P OLED display  http://bit.ly/JFb79Z , it is now apparent that this didn’t happen.   http://engt.co/IpwdXs  Samsung has not abandoned PenTile and still counts on PenTile for such high resolution OLED displays such as the Galaxy S3 with a 306 PPI layout.

When bloggers refer to PenTile Super AMOLED as being cheaper, I have to ask them, “Cheaper than what?”  Show me a comparable, high resolution RGB stripe AMOLED display to compare this to.  If there is no such displays any discussion of relative cost is meaningless.  PenTile technology remains an enabler for high resolution OLED applications, not a cost reducer.  And, as long as the demand for ever increasing resolution continues you will see many more such PenTile OLED designs.

Increasingly I am seeing blogs that ask what is wrong with PenTile anyway.  Despite the vocal critics, at a pixel pitch in the range of 300ppi+  PenTile technology is a great fit for these applications.

Just Look for Yourself

While it seems fashionable to criticize PenTile technology, increasingly we are reading blogs that refer to PenTile displays as  “oft maligned” but “looks fine to me”.   The reality is that as PenTile technology has moved to the higher end of resolution >300 ppi it doesn’t look less than sharp.  One example was this recent post regarding the RGBW in the Nokia E6.  Most people do not even realize that this display is a PenTile LCD.

http://bit.ly/HrspZI

This author, who never specifically noted that this displays was PenTile technology,  commented:

“…But we have no issues with the crispness and the brightness of the display as it works well with 640 x 480 …”

It comes down to looking at PenTile displays for yourself and not being misled by any negative blogs or claims of fuzzy text.

PenTile at the 2012 Superbowl

Samsung Galaxy Note Superbowl Ad

With all of the focus on the Superbowl and the Superbowl ads it was gratifying to see two ads for PenTile equipped products in a single Superbowl.  One was for the Galaxy Note with a 5.3-inch diagonal 800 x 1280 format PenTile OLED display http://bit.ly/yW5brS  The other ad was for the Motorola RAZR with a 4.3-inch qHD format PenTile OLED display. http://huff.to/wqqHYr

By my count today PenTile has shown up in 118 products to date.

Opportunity to Learn More About PenTile Technology

For those who would like more information about PenTile OLED and PenTile RGBW technologies for mobile products, you may wish to attend the up coming talk by Nouvoyance CEO Candice Brown Elliott in Southern California, “AMOLED vs. Hi-Res LCD for Premium Cell Phones”.  She will be speaking at the Los Angeles Society for Information Display Chapter’s annual symposium on “Emerging Display Technologies” on February 3rd, 2012.  For more information regarding attending the symposium, visit the LA SID Chapter website:  http://www.sid.org/ConferencesExhibits/LAChapterEmergingDisplayTechConference.aspx

 

Ms. Brown Elliott will also be speaking in Northern California, at Stanford University on the 28th of February on the topic of “Reducing Field Sequential Color Break-Up Artifacts using a Hybrid Display with Locally Desaturated Virtual Primaries”.  This talk will cover the development of the PenTile Hybrid Multi-Primary Field Sequential Color display that was demonstrated by Samsung in their DisplayWeek 2011 booth last May in Los Angeles.  For more information regarding attending the talk, visit the Stanford Center for Image Systems Engineering website:  http://scien.stanford.edu/

Not all RGBW Displays are Created Equal

Perhaps you may have noticed that LG introduced an RGBW OLED TV at CES, using a white OLED process together with traditional RGB+Clear color filters.

http://www.oled-info.com/lg-55em9600

The purpose of this was ostensibly to facilitate the manufacturing of a large diagonal OLED, that is traditionally difficult with shadow mask deposition techniques.  My assumption is that they used RGBW to enhance brightness, taking advantage of their white OLED material to attain the longer 30,000 hours or more of  lifetime which is now expected for TVs.  At CES I was told that the layout was a QUAD layout, which uses 4 subpixels per pixel, unlike PenTile that uses, on average, 2 subpixels per pixel achieved through subpixel rendering.

Similarly, we are also seeing additional announcements of products by Sony using their Sony Whitemagic™ technology.

http://news.in.msn.com/technology/article.aspx?cp-documentid=5762843

The layout of RGBW for Whitemagic also has used 4 subpixels per pixel unlike PenTile’s 2 subpixels per pixel on average.  While Sony’s stated purpose for Whitemagic has been to enhance power efficiency, a 4 subpixel per pixel layout only take advantage of the improved light throughput of clear subpixels.  It is, no doubt, an improvement to power efficiency, but it forgoes the chance to improve aperture ratio, which a significant part of what is achieved with PenTile technology.  As one moves to increasingly higher resolution formats aperture ratio becomes a major limitation, even for low temperature polysilicon (LTPS) backplanes.  For PenTile, however, the contribution of improved efficiency in our highest resolution designs is equally attributable to improvements in aperture ratio as well as the improved throughput gained from clear color filters.

Competitive RGBW is a step in the right direction, but there is no substitute for genuine PenTile technology.

Larger WVGA OLED Phone Displays

I have noticed a question reoccurring recently about some larger SVGA phones being announced at CES.  It can be said in general that an WVGA format (800 x 480) OLED phone with more than 4.1-inch diagonal will be an RGB stripe display rather than PenTile OLED.  Such a large WVGA format, such as that in the newly announced Nokia Lumina 900 (4.3-inch WVGA) would be too coarse of a pixel density to recommend PenTile due to increased pattern visibility.  For sizes of 4.1″ or less for WVGA it is necessary to use PenTile to enable the manufacturing of a phone that meets the required specifications for an OLED display in a phone.  This says nothing about any given manufacturers preference for RGB stripe over PenTile or PenTile over RGB stripe, but a simple decision based upon the size and resolution of the display.