The addition of two small RFID “Pills” about the size of a grain of rice will allow the position and orientation of any object placed on the screen to be tracked with ease. These inexpensive Pills are similar to those used currently for pet identification.
A small RFID Pill similar to a currently available subcutaneously inserted pet ID “chip” augmented with a small light sensitive photodiode. Such an RFID transponder can transmit not only its unique ID, but also data received from its photo sensor or other sensor such as a “fire button” on a toy piece. The optical message can allow the position and orientation of the toy on the screen to be computed.
An optically sensitive triangulating tag can be designed with off the shelf components. A photodiode or an infrared receiver of the type used in remote controls can be attached to a “dual access RFID tag.” The data from the photo sensors can be read via RFID, thus enabling the position of the toy to be tracked.
IdentiToyTag Schematic download.
The optically triangulating tag can be a pill type or even a flat circuit board as shown above. The physical separation of the two photo receptors allows the orientation of the tag to be determined.
The optical positioning information sent to the toy from the base can be a subliminal modulation of the image on the screen, or it can be by modulation of the backlight. Backlight modulation can be simulated by an array of LEDs. These LEDS can be modulated at a frequency of around 40 KHz to be compatible with commonly available IR remote control receiver chips.
IdentiToyBase Schematic download.
IdentiToy has developed a position emitting IR LED array capable of emitting 40 KHz modulated IR signals that can be read by any standard remote control receiver. This board can be made available to developers.
The IdentiToy base creates IR based position encoding signals. These signals can be a part of the LCD backlight. The small 128 LED array is designed to show the proof of concept of such a solution. It is intended that the final design be an edge-lit LCD solution with comb shaped light guides (requiring X+Y position emitters rather than X*Y position emitters).
IdentiToyBase Schematic download.
A new generation of dual access RFID Tags can transmit not only their unique ID, but also a user defined message which is written into a part of its memory. Continuously updating this user-defined message area with either position coordinates or data from sensors on the toy, such as a fire button, allows a fully interactive application to be developed.
A position emitting backlight can be made relatively inexpensively by the use of light guides. This allows X+Y emitters to be placed on the perimeter, instead of X*Y emitters directly behind the image. Since the position encoding message at any X or Y coordinate is always the same the LEDs can be easily driven by an inexpensive electronics. The light guides can be made by sandwiching many thin sheets of plastic with opaque sheets in between or by laser cutting grooves in a flat sheet of plastic.