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Sharp LCD Screen Doubles As Image Sensor

Sharp VGA LCD Sensor Screen (Images courtesy Tech-On!)
By Andrew Liszewski

As if I wasn’t already paranoid enough about accidentally getting fingerprints on my phone’s screen Sharp has just developed a new LCD technology that encourages that behavior. The new 2.6-inch VGA (640×480) LCD was unveiled at the ISSCC 2007 event in San Francisco and will be used to add touch-panel input functionality as well as biometric capabilities to mobile devices like phones and PDAs. Apparently other companies have developed similar LCDs in the past but Sharp’s version allows for a higher resolution output from the sensor at a low cost.

The real breakthrough made by Sharp was a proprietary TFT fabrication technology called the continuous grain (CG)-Silicon TFT process:

…This technology enables the integration of circuits with multiple functions on a single glass substrate by the same film formation process.

Based on this process, a PIN photodiode that converts incident light into the electrical signal and the TFT that drives the display panel are formed on the Si thin film on the same glass substrate. The photodiode is formed adjacent to the TFT so that they can share the same bus, thereby allowing the function as a sensor circuit even without the resetting and row-selecting transistors.

Unfortunately at the moment there is no information on when this technology might be included in future mobile devices.

[ Sharp LCD Screen With Image Sensor @ Tech-On! ] VIA [ SlashPhone ]