Touch Screens Everywhere

Posted by  29 April 2010

Computing is getting closer to the consoles we see on old episodes of Star Trek TNG, with everything seeming to go touch screen these days. It is actually uncanny how the touch screens resemble the shiny black sleek things that Captain Picard used to use. The latest hot gadget to leverage this technology is, of course, the Apple iPad.

 Star-Trek-screen

Example of a Star Trek touch screen: (http://www.startrek4u.com/special/multimedia/lcars/curry/enterprise-e-engineering-ne.png)

Enabling technology is an important precursor to great systems and consumer acceptance of new and nifty products. For example, from a semiconductor standpoint, you could argue that the driving force behind the success of devices like portable music players was the availability of huge amounts of small and inexpensive memory.


Now with touch screens, the enabling technology is powering a whole new type of application development for systems and software design. The combination of smart phone ubiquity and emerging tablet computing opens billions of new sockets, where the secret sauce for the next killer app is once again the semiconductor technology that is beneath.


With a market forecasted to grow to $9 billion dollars by 2015 (from $3.6 billion in 2008), there has been a flurry of activity in this sector, with some analysts reporting over 170 suppliers in the supply chain today (source = DisplaySearch).

To illustrate the innovation we will use Apple – a current (and deserved) media darling who has done an exemplary job integrating touch screen technology. 

What makes a touch screen controller work?

The most popular technology used in touch screens is the resistive 4-wire and 5-wire approach, due to low cost and simple interface electronics. There is also a recent notable increase in overall shipping of products based on the Projected Capacitive Touch (PCT) approach. This latter technology is used by Apple and others, including the Samsung Pixon12 and Sony Ericsson Satio.


Controlling the screen is managed through a variety of chipset solutions. Staying with our example, Apple used to use a 5-chip solution in the original 2G phone, evolved to a 3-chip solution, and now its latest devices use a single Texas Instruments chip – the 343S0487. This latest TI chip has documented design wins in the iPod Touch, iPhone, and Magic Mouse – but notably not the iPad.


Getting the required touch functionality onto the 343S0487 single chip was facilitated by fabricating at 90 nm. This gave the required density to put all this functionality into a small footprint and at a low cost. This device has a contacted gate pitch of ~341 nm and a metal 1 half pitch at ~155 nm. The device further features five metals and an aluminum RDL. By comparing the CMP, we do see a fill pattern characteristic of Texas Instruments, and can conclude that the device is likely manufactured within one of its fabs.

 touch-screen-image2

touch-screen-image3

 

In fact, TI has also been gaining some other big socket wins in this industry, notably the Motorola DROID resistive touch screen (using TI’s TSC2046 4-wire touch screen controller with low voltage digital I/O). What is different about this chip versus the one found in the Droid is that the device made for Apple contains over 50% digital components and memory versus a simple analog chip that looks very similar to the Burr Brown version made 10 years ago (TI acquired Burr Brown). Getting all of Apple’s advanced features clearly requires some relatively heavy processing power.

To see an annotated die photo of the TI 343S0487, you’ll need to visit our page promoting die photos of several of the touch screen controllers we have in inventory (scroll to bottom of page).


Although the focus of this article has been on Texas Instruments, a number of other innovative suppliers are in this market, including Cypress, Analog Devices, Broadcom, Synaptics, eGalax_eMPIA , and others. In the end there will, of course, be winners and losers.  However, as the market matures, there is plenty of opportunity for all of these players to succeed with their own unique spin on the technology.

Last modified on Thursday, 29 April 2010 17:18