Abstract: A digital pen comprising a skeleton and a removable skin: the skeleton holding together in fixed relationship: an electric circuit; an acoustic transmitter, detached from said electric circuit, and configured to transmit acoustic signals; and a resilient holder, configured to mechanically press said electric circuit into electrical contact with said transmitter, so as to electrically connect said electric circuit and said transmitter; and the removable skin comprising a housing fitting over said skeleton.

Abstract: A digital pen comprising: an electric circuit, an acoustic transmitter, detached from the electric circuit, and configured to transmit acoustic signals, and a resilient holder, configured to mechanically press the electric circuit into electrical contact with the transmitter, so as to electrically connect the electric circuit and the transmitter.

Abstract: Apparatus configured for processing of both audible and ultrasonic sound inputs, including a sensor with a frequency response spanning both audible and ultrasonic frequencies, and processing electronics configured to separate the audible and ultrasonic input frequencies for independent use. Apparatus configured for processing of both audible and ultrasonic sound inputs, including a sensor with a frequency response spanning both audible and ultrasonic frequencies, and processing electronics configured to process each one of the audible and ultrasonic input frequencies independently. Related apparatus and methods are also described.

Abstract: A computing system comprises a processor and internal peripheral devices, and a system bus connecting the internal peripheral devices to the processor. One of the internal peripheral devices is an ultrasonic digitizer that digitizes ultrasonic signals from at least two associated microphones into a digitized audio signal carrying a corresponding location and outputs the digitized audio as a signal on the system bus.

Abstract: A computing system comprises a processor and internal peripheral devices, and a system bus connecting the internal peripheral devices to the processor. One of the internal peripheral devices is an ultrasonic digitizer that digitizes ultrasonic signals from at least two associated microphones into a digitized audio signal carrying a corresponding location and outputs the digitized audio as a signal on the system bus.

Abstract: A digital pen comprising: an electric circuit, an acoustic transmitter, detached from the electric circuit, and configured to transmit acoustic signals, and a resilient holder, configured to mechanically press the electric circuit into electrical contact with the transmitter, so as to electrically connect the electric circuit and the transmitter.

Abstract: A digital pen comprising: an electric circuit, an acoustic transmitter, detached from the electric circuit, and configured to transmit acoustic signals, and a resilient holder, configured to mechanically press the electric circuit into electrical contact with the transmitter, so as to electrically connect the electric circuit and the transmitter.

Abstract: A receiving unit for receiving an acoustic signal from a digital pen, comprises: at least two ultrasound receivers, for receiving ultrasound signals from the digital pen; an electric circuit connected to said ultrasound receivers, and configured to extract ultrasound signals received by said ultrasound receivers, to enable tracking a position of said pen, and a biased clip for holding paper in fixed relationship to said ultrasound receivers. The clip may be metal, and alignment and location features may be provided for fitting sheets of paper for writing.

Abstract: A digital pen comprising a skeleton and a removable skin: the skeleton holding together in fixed relationship: an electric circuit; an acoustic transmitter, detached from said electric circuit, and configured to transmit acoustic signals; and a resilient holder, configured to mechanically press said electric circuit into electrical contact with said transmitter, so as to electrically connect said electric circuit and said transmitter; and the removable skin comprising a housing fitting over said skeleton.

Abstract: A receiving unit for receiving an acoustic signal from a digital pen, comprises: a housing; at least two ultrasound receivers, for receiving ultrasound signals from the digital pen, the ultrasound receivers comprising electret microphones, the electret microphones being located in location holes in the housing; and an electric circuit connected to said electret microphones, to extract ultrasound signals received by the ultrasound receivers. An attachment device may removably attach the receiving unit to another item.

Abstract: A computing system comprises a processor and internal peripheral devices, and a system bus connecting the internal peripheral devices to the processor. One of the internal peripheral devices is an ultrasonic digitizer that digitizes ultrasonic signals from at least two associated microphones into a digitized audio signal carrying a corresponding location and outputs the digitized audio as a signal on the system bus.

Abstract: A digital pen input system for allowing a user to write or draw by interacting with sheets of paper and allowing electronic tracing of pen movements for digital storage or display, the input device comprising a holder for sheets of paper, and a unit for detecting exchange of a current sheet, the system comprising: an autonomous page changing detector for autonomously detecting an action being a direct part of the exchange of a current sheet; and a data-stream insertion unit for inserting a new page indicator into a data stream emerging from the pen movements, at a location in the stream indicated by a time of the detecting, the new page indicator being a display instruction to separately display pen movements located before and after the new page indicator as separate pages.

Abstract: Apparatus configured for processing of both audible and ultrasonic sound inputs, including a sensor with a frequency response spanning both audible and ultrasonic frequencies, and processing electronics configured to separate the audible and ultrasonic input frequencies for independent use. Apparatus configured for processing of both audible and ultrasonic sound inputs, including a sensor with a frequency response spanning both audible and ultrasonic frequencies, and processing electronics configured to process each one of the audible and ultrasonic input frequencies independently. Related apparatus and methods are also described.

Abstract: A digital pen comprising: an electric circuit, an acoustic transmitter, detached from the electric circuit, and configured to transmit acoustic signals, and a resilient holder, configured to mechanically press the electric circuit into electrical contact with the transmitter, so as to electrically connect the electric circuit and the transmitter.