LCD screen can recognize what happens in front of it

A new modified version of a normal LCD screen has been developed that can see the world in front of it in 3D, thus giving the viewer the power the control the options/objects on screen without actually touching it or using a mouse a conventional remote control. More over it can also work as a 3D scanner.

The technology has been developed by an Indian scientist Ramesh Raskar at the Massachusetts Institute of Technology media Lab. He states that “This is the level of interaction that nobody has ever been able to do before.” He along with his colleagues presented a prototype 20” screen at Brown University in Providence, Rhode Island. They call it the Dubbed Bi-Directional Screen or simply Dubbed BiDi.

A 3D image will be made on the screen if an object is spinned in front of it. BiDi Screen is an example of a new type of I/O device that possesses the ability to both capture images and display them. BiDi screen is capable of capturing both touch and off-screen gestures through the use of embedded optical sensors.



Some characteristics of BiDi are discussed below:

Better Focusing Ability

Currently manufacturers are experimenting with the LSD by adding optical sensors between panel pixels, this will give the screen a touch screen interface.

This feature is definitely a positive for the innovation but a negative to this feature is that this display will have a poor vision. The image will not be focused. This drawback of a normal LCD has been catered for in BiDi by placing a tiny lens slightly in front of the sensor. This drastically improved the quality of the image. Thus the LCD screen of BiDi performs the job of a lens array.

Pinhole Pixels

In a conventional LCD a layer of liquid crystals is used to control the brightness of each of the pixels. These crystals can swivel to physically control displays backlight. Whereas in BiDi this concept is used in the other way around to control the amount of light passing onto the array of sensors behind the display.

During normal operation the liquid crystals block the pixels of BiDi but the liquid crystals of the regular hundreds of pixels spread around the screen are used to create a tiny hole which acts as a pinhole camera lens. This camera focuses the image in front of the screen onto a thin behind the LCD which is then detected by a camera. Thus BiDi knows what is happening in front of it.

According to the project team, "The BiDi Screen uses a sensor layer, separated a small distance from a normal LCD display. A mask image is then displayed on the LCD. When the bare sensor layer views the world through the mask, information about the distance to objects in front of the screen can be captured and decoded by a computer."

While BiDi technology is working the normal LCD is also doing its job, thus providing the image. In simple words a normal LCD screen is put to double duty.

Stereo Imaging

Using the different pinholes and using small information from each of their image from their different viewpoints the screen reconstructs stereoscopic images. All the images from each pinhole are combined to make the final image. By doing so the system can calculate how far away the object is from the screen.

Multiple images are produced, each focused on a different plane in front of the screen all the way to, say, 50 centimeters away from the screen, for instance, your hand will be blurred except in the one image that’s at the right depth.

No extra time is consumed for processing, the gestures are interpreted as an input by the computer software to control the objects on the screen.

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