US Patent 8022943 Controller arrangement for an optical sensing pen

Provided is a controller arrangement for an optical sensing pen having a nib. The controller arrangement is configured to operatively sense location data by sensing location tags on a page of printed media, and to calculate an orientation of the pen and a nib-to-tag distance. The controller arrangement includes an infrared (IR) illumination LED and image sensor assembly configured to transmit IR light onto, and receive IR light reflected from, respectively, the page of printed media. The controller arrangement also includes a force sensing infrared LED and photodiode assembly configured to detect when the nib contacts the page so that the sensor assembly is only activated when the nib is in contact with said page, and an accelerometer configured to allow the controller to sense motion without reference to the location tags. The controller arrangement further includes a transceiver and antenna assembly, and a processor arranged in signal communication with, and configured to control, the sensor assembly, the photodiode assembly, the accelerometer and antenna assembly to operatively calculate the orientation of the pen and the nib-to-tag distance, and to transmit the location data to a computing system.