Smartphone manufacturers are doing a good job at producing thinner, lighter smartphones with bigger and bigger displays. But it seems that we are quickly running up against the limits of how thin our smartphone bezels can get. LG and Samsung are currently leading the way on the thin bezel front, but although LG’s 1mm bezel prototype, which it flaunted last year, may have given us a glimpse of what’s to come, so far none of last year’s bezel-less device rumors have come to fruition.
Enter CrucialTec, a South Korean fingerprint sensor and touch panel manufacturer, which is preparing to launch a new display technology that may finally usher in the promised era of bezel-less smartphones.
As well as enabling slimmer devices or larger displays, CrucialTec is also leading the way with its range of new touchscreen panel embedded with fingerprint sensors. This is something that we’re likely to see much more of in the future, given the inclusion of biometric security measure in the iPhone 5S and Samsung Galaxy S5. In fact, CrucialTec was rumoured to have agreed to a deal to supply fingerprint sensors to Samsung Electronics for the Galaxy S5, something which the company now denies, and that has obviously not panned out.
I know what you’re thinking — we’ve heard promises of bezel-less handsets for more than a year now, so what makes CrucialTec’s claims more valid than anything else we’ve heard? Well, for a start, this is coming straight from the mouth of a manufacturer.
CrucialTec’s CEO is predicting that smartphones featuring the company’s new panel would be unveiled as early as the first half of this year, so anytime soon. Furthermore, the company has been relatively forthcoming about how its technology works, so let’s investigate how CrucialTec plans to rid us of smartphone bezels.
Existing technology – under the microscope
Leader of the thin-bezel pack – the Alcatel OneTouch Hero
Although there are a range of different touchscreen technologies in use across a range of smartphones, especially when you compare old and new models, most modern devices which support multi-touch are built using capacitive touch screens. Essentially, this means that inside the display there are rows and columns of capacitors which will alter their charge when you place your finger on or near them. Electronic devices, like Samsung’s S Pen, can also affect the capacitors’ magnetic fields, and “touch-less” features, like Samsung’s Air View, make use of more sensitive capacitors to achieve the same results at greater distances.
Anyway, the important thing to note here is that all of these touchscreens make use of two separate capacitor layers in order to accurately detect the location of your finger, one in the X plane and one in the Y plane. This is especially important for multi-touch features, as you can detect multiple changes in capacitance at points on both the X and Y axes quite easily. Resolution (accuracy) can be increased by adjusting the number of columns and rows. In order to detect current changes in these planes, additional circuitry is required around the edge of the capacitive display, which is where bezel limitations start coming into play.
Additionally, when it comes to manufacturing, this method of recording data from two separate axes is not ideal. Current designs require the use of two capacitive layers (X and Y), plus an insulating layer between them to avoid crosstalk between signals. After that, there’s the protective glass screen and wiring layers too. Considering that a malfunction in any layer would ruin the entire device, yields are a really important for current display technology.
Single Layer Manufacturing
This brings us to the key difference with CrucialTec’s technology, named matrix-switching touch screen panel (MS-TSP). CrucialTec touchscreens are built using a single capacitive layer, rather than two plus a layer of insulation. (It should be noted that other developers are working on this technology too, but CrucialTec is currently the most forthcoming with information about how it works.)
A single layer presents problems of its own, the biggest one being how to tell two parts of the screen apart effectively. Rather than creating a matrix of x and y locations, CrucialTec’s single layer technology uses a cell by cell grid system to detect location. This has essentially the same effect for the user as the X and Y system, but instead of collecting data from two points to create a coordinate, each grid is assigned its own location which is then interpreted by a direct connection to an integrated control circuit. One of the biggest challenges with this technology is accuracy, especially when dealing with potential noise generated from other components.
The control IC becomes much more complicated and has to be robust enough to interpret the locations accurately, hence why development has been slower than X by Y touchscreens. If this all works well, you’re looking at a touchscreen that has an even easier time of locating multiple finger placements, with excellent control over resolution, sensitivity, and size, as each cell can be controlled and calibrated individually.
The immediate benefit here is that you’re instantly cutting down the number of components that can go wrong, resulting in better production yields and less wastage. Current designs are based on a 4 mask process, ITO-X, ITO-Y, as well as a metal layer for each, whilst CrucialTec is using just a single ITO-XY layer. The company puts its yield rate for this technology at over 90% for the whole display, whilst the 4 mask process has a similar success rate for each component. This works out at around a 30 percent cost saving for CrucialTec, which could end up making its displays cheaper than the current crop.
There are a couple of other benefits to this manufacturing method too. Obviously, fewer layers also makes for a thinner display — under 0.5mm compared with just under 1mm for traditional multi-layer displays, which will result in thinner handsets for consumers, or more space for smartphone manufacturers to fit larger components under the display, such as bigger batteries.
Speaking of battery life, using a single layer also means that more light can pass through from the backlight to the top of the display and the user’s eyes. CrucialTec suggests that the maximum light transmittance of the older design is around 88%, whilst its own technology can pass around 94% of light produced from the backlight. So your displays could end up a little brighter, or even better yet, you could turn the screen brightness down a notch and still receive the same perceived brightness, which would make for a healthy battery saving, especially on larger devices. As we know, the screen is one of the biggest battery drainers in modern smartphones.
Finally, the entire point of the article was bezels, and the single layer production method can, on paper, lead to devices which do away with the need for bezels. As the diagram below shows, the MS-TSP method does away with all of the external circuitry around the edges of the capacitive layers. All of the connections simply come out of the bottom of the display, which is connected to the driver control IC elsewhere in the handset.
Now whether or not we really want truly bezel-less devices is up for debate. After all, portable technology is likely to encounter the odd accidental drop from time to time.
Perhaps truly bezel-less will be saved for monitors or TVs; even so, the technology has several other benefits for our smartphones. As well as thinner bezels and devices, this display technology could help reduce battery drain, free up room for other components, such as a larger camera, or allow manufacturers to release handsets with even larger displays.
With devices looking to ship as early as the first half of this year, we could soon have our first look at an ultra-thin bezel, super-slim handset, that’s lighter and more battery efficient than other smartphones on the market right now. Don’t forget about the integrated fingerprint scanner technology too.