# US 2013/0155014 A1 · Capacitive cordless writing device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0155014 A1 - Document ID: US20130155014A1 - Status: Published application - Kind: A1 - Application number: 13/716,490 - Filed: 2012-12-17 - Published: 2013-06-20 - Earliest claimed: 2011-12-19 - Assignees: Egalax_Empia Technology Inc. - Inventors: SHANG-TAI YEH - Web page: https://patentgrep.com/patent/US20130155014A1 ## CPC - G06F 3/03545: {Pens or stylus} - G06F 3/0416: {Control or interface arrangements specially adapted for digitisers} - G06F 3/04162: {for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware} - G06F 3/04166: {Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving (Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184)} - G06F 3/044: by capacitive means - G06F 3/0441: {using active external devices, e.g. active pens, for receiving changes in electrical potential transmitted by the digitiser, e.g. tablet driving signals} - G06F 3/0442: {using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser} - G06F 3/0488: using a touch-screen or digitiser, e.g. input of commands through traced gestures - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract When a touch sensor is approached or touched by a capacitive pen in a small area, the corresponding approach or touch signal might be slightly less than the threshold originally used for normal detection. By comparing the sum of the corresponding approach or touch signal and some adjacent signals with the threshold, the approach or touch of a small-area object that otherwise would not be detected by the original method can be determined. The capacitive pen can be made of bonded conductive fibers. ## Claims ### Claim 1 A cordless capacitive writing device, comprising: a touch sensor including a plurality of conductive strips including a plurality of first conductive strips and a plurality of second conductive strips; a capacitive pen including a conductive pen head for receiving a driving signal from the touch sensor and a signal conversion circuit for generating a delayed driving signal based on the driving signal after delaying a predefined period of time, the delayed driving signal being transmitted to the touch sensor through the conductive pen head, wherein the driving signal and the delayed driving signal have the same frequency and phase; and a controller for detecting the location of at least one external conductive object based on a change in capacitive coupling of the driving signal between the touch sensor and the at least one external conductive object in a passive mode, and detecting the location of at least one external conductive object based on the delayed driving signal received from the capacitive pen in an active mode. ### Claim 2 (depends on 1) The cordless capacitive writing device of claim 1, wherein, in the passive mode, the controller detects the location of the at least one external conductive object at the same time the driving signal is being provided, whereas in the active mode, the controller detects the location of the capacitive pen in the absence of the driving signal. ### Claim 3 (depends on 1) The cordless capacitive writing device of claim 1, wherein in the active mode, the controller simultaneously provides the driving signal to all of the first conductive strips, all of the second conductive strips, or all of the conductive strips. ### Claim 4 (depends on 1) The cordless capacitive writing device of claim 1, wherein in the active mode, the controller determines a first one-dimensional (1D) coordinate from signals of the first conductive strips, and determines a second 1D coordinate from signals of the second conductive strips, wherein the first and second 1D coordinates form a two-dimensional (2D) coordinate. ### Claim 5 (depends on 1) The cordless capacitive writing device of claim 1, wherein the frequencies of the driving signal provided in the active mode and the driving signal provided in the passive mode are different. ### Claim 6 (depends on 1) The cordless capacitive writing device of claim 1, wherein the touch sensor further includes a shielding conductive strip provided with a DC signal in the active mode to shield the conductive strips from external noise interference, and provided with an AC signal in the passive mode, the shielding conductive strip being provided with the AC signal forms a first coil that generates an electromagnetic signal. ### Claim 7 (depends on 6) The cordless capacitive writing device of claim 6, wherein the capacitive pen further includes a second coil for providing power necessary for generating the delayed driving signal by the signal conversion circuit through electromagnetic induction with the electromagnetic signal of the first coil. ### Claim 8 (depends on 6) The cordless capacitive writing device of claim 6, wherein the driving signal received by the capacitive pen is the electromagnetic signal generated by the first coil. ### Claim 9 (depends on 1) The cordless capacitive writing device of claim 1, wherein the signal conversion circuit further includes an oscillating feedback loop for generating, based on the driving signal, the delayed driving signal of the same phase as the driving signal, wherein the working frequency of the oscillating feedback loop is the same as the frequency of the driving signal. ### Claim 10 (depends on 1) The cordless capacitive writing device of claim 1, wherein the capacitive pen further includes an internal capacitor for storing the power generated by the second coil through electromagnetic induction.