# US 5,708,458 A · Method of and apparatus for using the digitizer sensor loop array of a computing device as an antenna for a radio frequency link to an external data source > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,708,458 A - Document ID: US5708458A - Status: Granted - Kind: A - Application number: 08/356,706 - Filed: 1994-12-15 - Granted: 1998-01-13 - Earliest claimed: 1994-12-15 - Assignees: Compaq Computer Corporation - Inventors: Michael E. Vrbanac - Web page: https://patentgrep.com/patent/US5708458A ## CPC - G06F 3/0219: {Special purpose keyboards} - G06F 1/1626: {with a single-body enclosure integrating a flat display, e.g. Personal Digital Assistants [PDAs]} - G06F 1/1643: {the display being associated to a digitizer, e.g. laptops that can be used as penpads (details related to the relative motion of the display enclosure with respect to the body enclosure, e.g. to move between laptop and tablet PC configuration G06F1/1615)} - G06F 1/166: {related to integrated arrangements for adjusting the position of the main body with respect to the supporting surface, e.g. legs for adjusting the tilt angle} - G06F 1/1698: {the I/O peripheral being a sending/receiving arrangement to establish a cordless communication link, e.g. radio or infrared link, integrated cellular phone (details of antennas disposed inside a computer H01Q1/2266)} - G06F 3/0231: {Cordless keyboards} - G06F 3/041: Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means - G06F 3/04162: {for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware} - G06F 3/046: by electromagnetic means - G06F 2200/1632: Pen holder integrated in the computer - H01H 2207/048: Inductive or infrared coupling - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) - H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00) ## Abstract A pen-enabled computer system in which the digitizer sensor loop array is employed as a radio frequency antenna for receiving signals from an external signal source such as a wireless keyboard or wireless local area network interface. This radio frequency datalink arrangement allows for greatly enhanced freedom of movement when using external system components, as well as reduced component count and weight. ## Claims ### Claim 1 A pen-enabled computer system for use with an external radio frequency serial data signal source including a radio frequency transmitter for transmitting a serial datastream radio frequency signal, the computer system comprising: a digitizer pen; a digitizer sensor loop array for cooperatively communicating with said digitizer pen and for receiving the serial datastream radio frequency signal, wherein the serial datastream radio frequency signal is provided by a source other than said digitizer pen; and receiver circuitry electrically coupled to said digitizer sensor loop array, said receiver circuitry including means for retrieving the serial datastream radio frequency signal received by said digitizer sensor loop array and for providing a digital signal responsive to the serial datastream radio frequency signal. ### Claim 2 (depends on 1) The computer system of claim 1, wherein said digitizer pen provides a pen radio frequency signal, and further comprising: digitizer control circuitry coupled to said digitizer sensor loop array, said digitizer control circuitry including means for differentiating said pen radio frequency signal from the serial datastream radio frequency signal and means for translating said pen radio frequency signal received by said digitizer sensor loop array into pen location data for use by said computer system. ### Claim 3 (depends on 2) The computer system of claim 2, wherein the serial datastream radio frequency signal is modulated at a frequency different than the transmission frequency of the pen radio frequency signal, and wherein said means for differentiating includes a first filter tuned to pass the serial datastream radio frequency signal and a second filter tuned to pass said pen radio frequency signal. ### Claim 4 (depends on 2) The computer system of claim 2, wherein said means for differentiating includes data decoding circuitry for separating said pen radio frequency signal from the serial datastream radio frequency signal. ### Claim 5 (depends on 1) The computer system of claim 1, in which said external radio frequency serial data signal is provided by an external keyboard. ### Claim 6 (depends on 5) The computer system of claim 5 in which the keyboard includes light emitting diodes (LEDs) and keyboard receiver circuitry for reception of LED radio frequency control signals, the computer system further comprising: transmitter circuitry electrically coupled to said digitizer sensor loop array, said transmitter circuitry transmitting an LED control signal developed by said computer system for reception by the keyboard receiver circuitry for controlling LEDs on said external keyboard. ### Claim 7 (depends on 6) The computer system of claim 6, wherein said digitizer sensor loop array is integrated in a liquid crystal display unit. ### Claim 8 (depends on 1) The computer system of claim 1, in which said external radio frequency serial data signal is provided by a wireless computer networking interface. ### Claim 9 (depends on 1) The computer system of claim 1, wherein said means for retrieving includes frequency shift keying demodulation circuitry. ### Claim 10 (depends on 1) The computer system of claim 1, wherein said means for retrieving includes phase shift keying demodulation circuitry. ### Claim 11 (depends on 1) The computer system of claim 1, wherein said digitizer sensor loop array is integrated in a liquid crystal display unit. ### Claim 12 A pen-enabled computer system with wireless connectivity, the pen-enabled computer system comprising: an external keyboard transmitting a serial datastream radio frequency signal; a pen-enabled computer, including: a digitizer pen; a digitizer sensor loop array for cooperatively communicating with said digitizer pen and for said serial datastream radio frequency signal from said external keyboard; and receiver circuitry electrically coupled to said digitizer sensor loop array, said receiver circuitry including means for retrieving the serial datastream radio frequency signal received by said digitizer sensor loop array and for providing a digital signal responsive to the serial datastream radio frequency signal to the pen-enabled computer. ### Claim 13 (depends on 12) The computer system of claim 12, wherein said digitizer pen provides a pen radio frequency signal, said pen-enabled computer further comprising: digitizer control circuitry coupled to said digitizer sensor loop array, said digitizer control circuitry including means for differentiating said pen radio frequency signal from the serial datastream radio frequency signal and means for translating said pen radio frequency signal received by said digitizer sensor loop array into pen location data for use by said computer system. ### Claim 14 (depends on 13) The computer system of claim 13, wherein the serial datastream radio frequency signal is modulated at a frequency different than the transmission frequency of the pen radio frequency signal, and wherein said means for differentiating includes a first filter tuned to pass the serial datastream radio frequency signal and a second filter tuned to pass said pen radio frequency signal. ### Claim 15 (depends on 13) The computer system of claim 13, wherein said means for differentiating includes data decoding circuitry for separating said pen radio frequency signal from the serial datastream radio frequency signal. ### Claim 16 (depends on 12) The computer system of claim 12, wherein said keyboard includes light emitting diodes (LEDs) and keyboard receiver circuitry for reception of LED radio frequency control signals, said pen-enabled computer further comprising: transmitter circuitry electrically coupled to said digitizer sensor loop array, said transmitter circuitry transmitting an LED control signal developed by said computer system for reception by the keyboard receiver circuitry for controlling LEDs on said external keyboard. ### Claim 17 (depends on 16) The computer system of claim 16, wherein said digitizer sensor loop array is integrated in a liquid crystal display unit. ### Claim 18 (depends on 12) The computer system of claim 12, wherein said means for retrieving includes frequency shift keying demodulation circuitry. ### Claim 19 (depends on 12) The computer system of claim 12, wherein said means for retrieving includes phase shift keying demodulation circuitry. ### Claim 20 (depends on 12) The computer system of claim 12, wherein said digitizer sensor loop array is integrated in a liquid crystal display unit. ### Claim 21 A system with wireless connectivity, the system comprising: a wireless local area network interface transmitting a serial datastream radio frequency signal; a pen-enabled computer, including: a digitizer pen; a digitizer sensor loop array for cooperatively communicating with said digitizer pen and for receiving said serial datastream radio frequency signal; and receiver circuitry electrically coupled to said digitizer sensor loop array, said receiver circuitry including means for retrieving the serial datastream radio frequency signal received by said digitizer sensor loop array and for providing a digital signal responsive to the serial datastream radio frequency signal to the pen-enabled computer. ### Claim 22 (depends on 21) The system of claim 21, wherein said digitizer pen provides a pen radio frequency signal, said pen-enabled computer further comprising: digitizer control circuitry coupled to said digitizer sensor loop array, said digitizer control circuitry including means for differentiating said pen radio frequency signal from the serial datastream radio frequency signal and means for translating said pen radio frequency signal received by said digitizer sensor loop array into pen location data for use by said computer system. ### Claim 23 (depends on 22) The system of claim 22, wherein the serial datastream radio frequency signal is modulated at a frequency different than the transmission frequency of the pen radio frequency signal, and wherein said means for differentiating includes a first filter tuned to pass the serial datastream radio frequency signal and a second filter tuned to pass said pen radio frequency signal. ### Claim 24 (depends on 22) The computer system of claim 22, wherein said means for differentiating includes data decoding circuitry for separating said pen radio frequency signal from the serial datastream radio frequency signal. ### Claim 25 A method for establishing a radio frequency data link between a pen-enabled computer system and an external serial data signal source, wherein the external serial data source is other than a pen, comprising the steps of: transmitting a serial datastream from the external serial data signal source; utilizing the digitizer sensor loop array of the pen-enabled computer system as an antenna for reception of said serial datastream; and demodulating said serial datastream for use as an input to said pen-enabled computer system. ### Claim 26 (depends on 25) The method of claim 25, in which said external serial data signal source is a wireless computer networking interface. ### Claim 27 (depends on 25) The method of claim 25, in which said external serial data signal source is an external keyboard. ### Claim 28 (depends on 27) The method of claim 27, further comprising the step of: utilizing said digitizer sensor loop array as an antenna for transmitting an LED control signal developed by said computer system for controlling LED's on said external keyboard. ### Claim 29 A pen-enabled computer system for use with an external radio frequency serial data signal source including a radio frequency transmitter for transmitting a serial datastream radio frequency signal, the computer system comprising: a digitizer pen; a digitizer sensor loop array for cooperatively communicating with said digitizer pen and for receiving the serial datastream radio frequency signal, wherein the serial datastream radio frequency signal is provided by a source other than said digitizer pen; and receiver circuitry electrically coupled to said digitizer sensor loop array, said receiver circuitry including demodulation circuitry for retrieving the serial datastream radio frequency signal received by said digitizer sensor loop array and for providing a digital signal responsive to the serial datastream radio frequency signal. ### Claim 30 (depends on 29) The computer system of claim 29, wherein said digitizer pen provides a pen radio frequency signal, and further comprising: digitizer control circuitry coupled to said digitizer sensor loop array, said digitizer control circuitry including discrimination circuitry for distinguishing said pen radio frequency signal from the serial datastream radio frequency signal and digital circuitry for translating said pen radio frequency signal received by said digitizer sensor loop array into pen location data for use by said computer system. ### Claim 31 (depends on 29) The computer system of claim 29, further comprising a keyboard, wherein said external radio frequency serial data signal is provided by said keyboard. ### Claim 32 (depends on 31) The computer system of claim 31, wherein said keyboard comprises: light emitting diodes (LEDs); and keyboard receiver circuitry for receiving LED radio frequency control signals; and the computer system further comprising: radio frequency transmitter circuitry electrically coupled to said digitizer sensor loop array, said radio frequency transmitter circuitry utilizing said digitizer sensor loop array as an antenna in transmitting an LED control signal developed by said computer system for reception by said keyboard receiver circuitry. ### Claim 33 (depends on 29) The computer system of claim 29, wherein said digitizer sensor loop array is integrated in a liquid crystal display unit. ### Claim 34 (depends on 29) The computer system of claim 29, wherein said digitizer sensor loop array is integrated in an active matrix display. ### Claim 35 (depends on 29) The computer system of claim 29, wherein said digitizer sensor loop array is integrated in a field emission display. ### Claim 36 A system with wireless connectivity, the system comprising: a wireless local area network interface transmitting a serial datastream radio frequency signal; a pen-enabled computer, comprising: a digitizer pen; a digitizer sensor loop array for cooperatively communicating with said digitizer pen and for receiving the serial datastream radio frequency signal; and receiver circuitry electrically coupled to said digitizer sensor loop array, said receiver circuitry including demodulation circuitry for retrieving the serial datastream radio frequency signal received by said digitizer sensor loop array and for providing a digital signal responsive to the serial datastream radio frequency signal. ### Claim 37 (depends on 36) The system of claim 36, wherein said digitizer pen provides a pen radio frequency signal, and further comprising: digitizer control circuitry coupled to said digitizer sensor loop array, said digitizer control circuitry including discrimination circuitry for distinguishing said pen radio frequency signal from the serial datastream radio frequency signal and digital circuitry for translating said pen radio frequency signal received by said digitizer sensor loop array into pen location data for use by said computer system.