True Facts about the OLED

[Dr. Lecter]

I'm curious if anyone can weigh in on details about OLED vs. current LCD screens, because from what I've seen recently the OLED is no longer the brightest, sharpest, highest resolution, best contrast, easiest to read, 'whatever adjective you choose' display option.

However, it's hard to quantify the differences between OLED screens, which are really awesome, and the new LCD screens, which are basically selected for their ability to be really awesome like the OLEDs at a lower cost. So, I'm hoping we can get some technical details about the various OLEDs and LCDs out there: max brightness, power consumption, resolution, max contrast, etc. Perhaps a better comparison than 'I think this one is slightly easier to read that that one' can be realized.

I haven't found a ton of tech specification detail on manufacturers' websites:

Shearwater calls the Predator's display a QVGA, Full-Color OLED, and the Petrel's a QVGA, Full-Color LCD. No other details.

Liquivision calls most of its various displays full color OLEDs, and the X1's a high contrast OLED. No other details.

Atomic says the Cobalt uses an AMOLED full color display. No other details.

With pleasantly predictable German precision, Heinrichs Weikamp tells us that the OSTC3 has "High resolution IPS LCD Monitor,Field of view: 160°, Resolution: 320 x 240 Pixel"; the OSTC2 has a "High resolution color-display, Field of vision: 170 °Contrast: 10000:1, Resolution: 320 x 240 pixels" (though I don't think it's an LCD display); and the DRx has a "High resolution IPS LCD Monitor, Field of view: 160°, Resolution: 320 x 240 Pixel."

DiveRite tells us its NiTek Q has a "Yellow OLED display."

 

[letterboy]

will be interesting to see if anyone has insight into this.

I forsee that they are all made by the same company in Taiwan, assembled by Mexican immigrants in Taiwan for a company that is owned by the Koreans....

 

[lindenbruce]

Here is a link that helps with understanding display resolutions. I don't know if this will answer part of your question. B.

Graphics display resolution - Wikipedia, the free encyclopedia

 

[KeithG]

Maybe if we had a simple layman's explanation of the fundamental differences in technology?

My understanding is
A) an LCD screen uses pixels to block light from passing through the screen (most often from a backlight)
B) an OLED screen contains a bunch of pixels that emit light

Not sure if this gets us anywhere....

 

[Ken T]

At the end of the day, even with all the technical data in front of you, it will probably still be a subjective experience anyways.

 

[RonR]

I can throw some basic concepts out, having recently done a lot of comparisons between various commercially available display technologies. But a caveat about claims and specifications- a lot of statistics re. displays have more to do with marketing than forming a real basis for comparison. Contrast ratios, for instance, will be far higher on OLED displays, but that doesn't necessarily translate into a more readable display, or past a certain threshold, into anything the eye can detect. Resolution- pixel size and dimensions- can be objectively stated. But things like max brightness just are't likely to be comparable in any useful, objective way- and power consumption, for instance, on the Cobalt, depends on what the screen is displaying at the moment. Both have a lot to do with firmware design.

You are basically dealing with three technologies. TFT LCD (thin-film transistor liquid crystal display), AMOLED (active matrix organic light-emitting diode), and PMOLED, usually called just OLED (passive matrix organic light-emitting diode). Both OLED technologies are emissive- little colored lights shining from the surface of the display when they are switched on. They look cool under a microscope. That means the pixels not switched on use no power- which is an advantage. Most LCD displays (in this discussion, anyway) are transmissive, meaning that the light from the backlight passes through the screen and the colored pixels- so the whole backlight needs to be on in order for the display to be seen. Both these have additional variations regarding the arrangement of the colored pixels and how that relates to color perception and the process of controlling the pixels, but giffenk has the basics right.

Dr. Lecter is correct in that newer TFT LCD displays are very, very good. Comparing them to the AMOLED displays used in the Cobalt and the earlier Shearwater, UEMIS, etc. the main difference is that the AMOLED's have a far wider viewing angle- almost 180° with no falloff in intensity. However the viewing angle for new LCD's is fairly wide, and I doubt if this is a significant difference in the context of a dive computer. Which one looks better comes down to a subjective judgement. In comparing lots of 320 x 240 (QVGA) screens, the AMOLED pixels typically seem brighter to my eye, and harsher in contrast, leading to a brighter, but more pixelated look- even though the pixel size is essentially identical. Most LCD screens are smoother looking. At the time we brought the Cobalt to market, AMOLED screens could be made to have a very bright display while consuming far less power than an equivalent LCD screen- a huge advantage. That advantage is now very slight, almost nonexistent. LCD display power consumption is mostly determined by the backlight and the backlight controller, these have become far more efficient. The IPS designation (in-plane switching) references one of the technologies that have helped make these displays more efficient, and is quite common now.

Active Matrix (meaning essentially that there is a transistor for each pixel) vs. Passive Matrix is a big issue for OLED screens, as PMOLED screens can't be made very large or with high resolution without having excessive power consumption. AMOLED is what all the buzz concerning large TV screens is about- they can be big, subject only to limitations of manufacturing processes. These have turned out to be very challenging. Which is why they are so expensive.

Most PMOLED displays are monochrome- orange or yellow or green or blue, rather than full color. These monochrome displays can be very power efficient. That's the Dive Rite display, and a lot of small consumer devices. Liquivison is using a full color PMOLED. This display technology doesn't get much larger than 160 x 128, 1.8" diagonal in full color, but it's very good at those smaller sizes. The number of pixels being switched is the basic limitation of the passive matrix technology.

For comparison, the AMOLED display used in the Cobalt is 320 x 240, and a 2.4" diagonal. It's the same display Shearwater used, as did UEMIS. It's a truly great display. Unfortunately, it's not being made any more, nor is there any replacement. It's my understanding that the factory could never get the yields up from their processes enough to make a profit. Cobalt still has it only because Atomic bought up all the displays they could find when the end of life announcement came. No one else has stepped into the gap to produce a small AMOLED for the general market yet, though there are apparently factories tooling up- but we are talking about billion dollar investments, often backed by governments, and years of development. Samsung does produce the small AMOLED displays used in their phones, but they won't sell them to you unless you are buying hundreds of thousands per month.

However, a number of LCD manufacturers have stepped up to make displays that are 320 x 240 and physically the same size, and use new technologies that keep power under control. In a device, they are actually very difficult to tell apart from the AMOLED. I expect this general class of computers with larger (QVGA), full color displays, will all be using very similar technologies for a while. I don't think quality of display is going to be a very meaningful distinction, for the most part.


Ron

 

[Kevrumbo]

I can't read my Liquivision Xen BT OLED in the shallows of tropical waters with bright ambient light all around even if looking directly face-on at the screen up close; I can read my Uwatec LCD BT & Petrel Computer color LCD no problem in bright ambient light.

At depth and in an overhead (wreck), I can easily see both the Petrel color LCD and Xen OLED active illumination display; the Uwatec LCD display requires shining a light source (canister torch or a chem stick) in order to read. . .

 

[RonR]

OLED displays must overcome the ambient light to be seen- like a light bulb on a bright sunny day, they can just disappear unless they are shielded from the brightest light by a hand or some such means. That's their Achilles' heel. "Transflective" LCD displays can have elements of both transmission and reflection to make legibility in bright light somewhat better- though usually not as good as when using a backlight in dim ambient light. It's the same issue as using a laptop screen outdoors vs. indoors. Reflective LCD displays, like the traditional black and white or grayscale used by older or less expensive dive computers, are readable in bright light but require a light source (backlight or external) to be seen in the dark.

Ron