Microsoft looks to bring back the light pen

July 23, 2012 // 11:49 a.m.

Tags: #capacitive-touch #light-pen #metro-ui #microsoft #microsoft-hardware #resistive-touch #touch-screen #touch-sensitive #windows-8

Microsoft's current focus on touch-display interaction - as evidenced by its pushing of Metro UI in Windows 8 and its Surface interactive tables and Windows-based tablet product lines - is clear, but it looks like the company has another trick up its sleeve: the reintroduction of the light pen.

A popular accessory in the eight-bit microcomputing era, the light pen as a product dates back to 1950s and the Whirlwind real-time computer system developed by the Massachusetts Institute of Technology for the US Navy. Its operation was simple: long before the idea of a mouse, it allowed the user to interact with a computer simply by pointing and clicking on the screen.

A light pen typically takes the form of a stylus which contains a small photoreceptor in its tip. This stylus tracks the light emitted by activated phosphor on a cathode-ray tube display - although later models work with liquid-crystal displays too - in order to figure out where on the screen the user is pointing. Using the light pen, an operator could quickly highlight large areas of text for modification and even - in later implementations - draw freehand.

light pens have largely disappeared thanks to the advent of various touch-sensitive overlay technologies which quickly add capacitive or resistive touch-detection capabilities to devices like tablets and mobile phones. Unlike a light pen, a touch-sensitive screen is typically operated using your fingertip or a cheap plastic stylus.

The downside of the current state of the art in touch-sensitivity should be obvious: it's near-impossible to add touch sensitivity to an existing desktop or laptop computer without replacing the display. Although add-on overlays do exist, these typically require dismantling the surround of the display - not something your average user feels particularly comfortable doing.

Faced with an operating system clearly designed to be prodded but an embarrassment of non-proddable computers on the market, Microsoft has apparently decided to bring back the light pen - a simple add-on device which can bring pen control to any computer or laptop on the market today.

According to Technology Review, which claims that Microsoft has not yet decided whether or not it will actually release the gadget, the system works by using a side-looking camera to peer at the display and read positioning information encoded in the blue pixels - blue being chosen to minimise the image disruption perceived by the human eye.

While clever, the design - created by Microsoft's Andreas Nowatzyk and Anoop Gupta - does have one drawback: it requires high-resolution image sensors which are currently hard to come by. As a result, the company has yet to decide whether it's worth developing the hardware required to make the reborn light pen a commercial reality.

One thing seems clear, however: Microsoft is doing all it can to ensure that Metro UI on the desktop is a success.