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Touchscreen Technology


Photo Courtesy of Garmin

Garmin's GPSmap 7212 offers a user-friendly interface.

Simple fingertip control and user-friendly operating systems combine to make powerful, intuitive electronics a reality.

In World War II, a top-secret research project taught pigeons to pilot missiles. The birds, strapped into the nose-cone of a missile, had been trained to peck at the image of a battleship on a screen. If the target was to the left, the birds pecked on the left-hand side of the screen, which made the missile turn left; if the image was to the right, the birds pecked right and the missile turned to the right.

Of course, modern touchscreens are much more sophisticated than the simple mechanical contraptions of Project Pigeon. But although there are now more than a dozen different touchscreen technologies, all have limitations. Some reduce screen brightness, some are horrendously expensive, some are fragile, and some won’t work if they get wet.

The GPS on my motorcycle, for instance, has a resistive touchscreen, in which the screen itself is slightly flexible. Underneath it are two very thin sheets of conductive material, held apart by spacers. When I touch the screen, the two sheets come into contact with each other, forming an electrical circuit. Measuring resistance in the circuit—from left to right and top to bottom—tells the software exactly where I touched.

But “touchscreen” is hardly the right word to describe it; “press-screen” would be nearer the mark because it requires far more than the feather-light touch of more recent technologies. But resistive touchscreens have advantages too: They can be waterproof, dustproof, and unbelievably rugged. And as a motorcyclist, the fact that they can be operated while I’m wearing gloves is crucial.

My kids’ Nintendo DSs have resistive screens too. They are relatively cheap, and using a plastic stylus makes them very accurate. But the double-conductive layer inevitably means that their screens aren’t as clear or bright as some of the alternatives.

One of those alternatives, selected by Garmin, Raymarine, and Simrad, is known as capacitive-screen technology. It uses a grid of microscopic conductors behind the screen, each carrying a small electric charge. When another conductor—such as a human finger—approaches the front face of the screen, some of the charge in the grid is attracted towards the finger. The grid’s capacitance (its ability to hold an electric charge) changes where it is touched and can be measured and interpreted by the touchscreen software, so they’re brighter.

Even capacitive screens have their drawbacks: They can’t be operated with gloved hands or non-conductive styluses, and although they are unaffected by rainwater, there are still potential problems when there are dollops of salt spray flying around. But they are quicker to respond than a resistive screen, and the single grid behind the screen lets much more light through than the double conductive layer of a resistive screen.


Photo Courtesy of Raymarine

The Raymarine E120 retains some manual controls.

As Simrad’s Mike Fargo told me “the trade-off between not being able to use it wearing gloves and being able to see the screen in sunlight is a no-brainer.”

But why go for a touchscreen in the first place?

“In the physical world,” explains Garmin’s Derek Hoy, “you use your hands to manipulate whatever it is you’re interacting with. A touchscreen is as close as you can get to this type of interaction. It allows you to sort of turn off the part of your brain that’s trying to figure out what tools to use to manipulate something.”

Jim Hands, of Raymarine, makes much the same point. “Touchscreen makes cursor-related tasks much easier. On our E-series Widescreens, you just tap the screen to drop each leg of a route. And touchscreen enables us to introduce niceties like virtual keyboards”—full QWERTY keyboards that can be used to name and organize waypoints and routes as easily on a multifunction device (MFD) as on a PC.

Yet none of these three have completely dispensed with knobs and buttons. Northstar (remember them?) was first out of the blocks, using LEDs and light-sensitive transistors to create an invisible grid of infrared beams to detect the presence and position of a pointing finger on the screen of its 8000i. But there was still a conventional control panel whose functions were duplicated by the touchscreen, rather than replaced by it.

Garmin was next up and went to the other extreme. Its 5000 series and later 7000 series MFDs have no twiddle-knobs at all, and the only push button is the one that turns the display on or off! iPhone enthusiasts love them, but for boaters who aren’t happy with the idea of paying a thousand-dollar premium for a touchscreen or who fear that it might be unreliable, difficult to keep clean, or awkward to use on a moving boat, the 5000 and 7000 series are paralleled by the 4000 and 6000 series, both with conventional controls.

The Hybrid touch controls of Raymarine’s E-Series Wide displays include both touchscreen and knobs and buttons that can be used interchangeably. “Touchscreen is the preferred option when you’re dockside and in calm waters,” says Hands, “but when you’re bouncing around in seven-foot seas, the positive feel of buttons and knobs makes manipulation of the user interface much simpler.”

Simrad’s NSS displays are the new kids on the touchscreen block. They’ve gone for an interesting midway option, with some functions controlled by the touchscreen and others through the minimal keypad and rotary knob. Fargo summed it up this way: “Touch is great for setup operations such as placing waypoints, but there’s still no better way of adjusting a proportional control such as zoom or gain than a rotary knob.

This article originally appeared in the August 2011 issue of Power & Motoryacht magazine.