Method, apparatus, and system for capacitive touch communication

• US 20130257804A1
• Filed: 03/29/2013
• Published: 10/03/2013
• Est. Priority Date: 03/29/2012
• Status: Active Application

• Current Assignee: Rutgers University
• Original Assignee: Rutgers University
• Inventors: Howard, Richard, Spasojevic, Predrag, Vu, Tam, Gruteser, Marco
• Application Number:
  US13/853,899
• Publication Number:
  US 20130257804A1
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/04162 for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware
• CPC Class Codes: G06F 3/044 by capacitive means

Abstract

A method, apparatus, and system for using a user device to communicate with a touch-screen of an electronic device includes generating, by an electronic circuit of the user device, a signal by encoding a data sequence that may be stored in a memory of the user device and communicating the signal from the user device, to the electronic device by varying a capacitance of the touch-screen thereof. The electronic device receives the signal to obtain the data sequence. The electronic device may use the data sequence to at least authenticate a user of the user device.

Claims

1. A user device, comprising:

a circuit to generate a signal; and

at least one electrode electrically coupled to the circuit and configured to communicate the signal to an electronic device by varying a capacitance of a capacitive touch sensor of the electronic device.

2. The device according to claim 1, further comprising a memory having a data sequence stored therein.

3. The device according to claim 2, further comprising a processor configured to generate signal based on the data sequence stored in the memory.

4. The device according to claim 1, wherein the signal is modulated using frequency modulation.

5. The device according to claim 1, wherein the signal is modulated using amplitude modulation.

6. The device according to claim 5, wherein the wherein the amplitude modulation is on-off keying.

7. The device according to claim 1, further comprising a second electrode electrically coupled to the circuit configured to communicate the signal to the external device using a user'"'"'s body as a communication medium, wherein the electrode is in contact with the user and the user is in contact with the capacitive touch screen.

8. A method for using a user device to communicate with a touch-sensor of an electronic device, the method comprising:

generating, by the user device, a signal encoding a data sequence;

communicating the signal from the user device, to the electronic device by varying a capacitance of the touch-screen thereof; and

receiving and decoding, by the electronic device, the signal to obtain the data sequence.

9. The method according to claim 8, further comprising identifying a user of the user device using the data sequence.

10. The method according to claim 8, further comprising authenticating a user of the user device using the data sequence.

11. The method according to claim 8, wherein the data sequence is stored on the electronic device, the method further comprising:

receiving, by the electronic device, a sequence of touch events generated in response to the signal;

training the electronic device by;

repeatedly transmitting, by the user device, the signal generated from the data sequence;

recording the sequence of touch events generated in response to the signal that is transmitted by the user device; and

aligning the sequence of touch events with the data sequence stored on the electronic device, wherein each bit of the data sequence is associated with a bit period that defines an amount of time during which the bit is transmitted.

12. The method according to claim 11, wherein aligning the sequence of touch events with the data sequence comprises, for each possible starting point in a first bit period:

counting a number of one-bit touch events, wherein a one-bit touch event is a touch event received in a bit period associated with a one bit;

counting a number of zero-bit touch events, wherein a zero-bit touch event is a touch event received in a bit period associated with a zero bit;

calculating a ratio of the number of one-bit touch events to the number of zero-bit touch events; and

selecting a starting point that results in the ratio being maximized.

13. The method according to claim 12, further comprising determining a touch event threshold based on the sequence of touch events, wherein the touch event threshold is the number of touch events that is least likely to occur in a bit period associated with either a zero bit or a one bit.

14. The method according to claim 13, further comprising:

on a condition that the number of touch events is greater than the touch event threshold, identifying the bit period as a one bit.

15. The method according to claim 14, further comprising:

on a condition that the number of touch events is less than the touch event threshold, identifying the bit period as a zero bit.

16. The method according to claim 8, wherein decoding the signal comprises:

receiving, by the electronic device, a sequence of touch events generated in response to the to the signal;

identifying a plurality of bit period sequences each having a unique starting position, and each bit period sequence comprising a plurality of bit periods;

for each bit period sequence, counting the number of events in each bit period;

generating a bit sequence for each bit period sequence by;

on a condition that the number of touch events is greater than a threshold, identifying the bit period as a one bit; and

on a condition that the number of touch events is less than a threshold, identifying the bit period as a zero bit;

comparing each bit sequence to a table of possible messages; and

selecting a message from the table that is most similar to the bit sequence.

17. A system for capacitive touch communication, the system comprising:

a first device comprising;

a signal generating circuit configured to generate a signal encoded with a data sequence; and

at least one electrode electrically coupled to the circuit and configured to communicate the modulated signal to a second device by varying a capacitance of a capacitive touch screen of the second device; and

the second device comprising;

a processor;

a capacitive touch sensor; and

a computer-readable storage medium storing instructions that, when executed, cause the processor to;

receive a sequence of touch events from the touch sensor generated in response to the varying capacitance of the capacitive touch-screen caused by the device; and

decode the sequence of touch events to obtain the encoded data sequence.

18. The system according to claim 17, wherein the data sequence is used by the second device to identify a user of the first device.

19. The system according to claim 17, wherein the first device further comprises a memory having the data sequence stored therein.

20. The system according to claim 19, where in the first device further comprises a processor configured to generate the signal by encoding the data sequence stored in the memory;

21. The system according to claim 17, wherein the instructions further cause the processor to:

receive a sequence of touch events generated in response to the signal;

record the sequence of touch events generated in response to the signal that is transmitted by the user device;

align the sequence of touch events with the data sequence stored on the electronic device, wherein each bit of the data sequence is associated with a bit period that define an amount of time during which the bit is transmitted;

for each possible starting point in a first bit period;

count a number of one-bit touch events, wherein a one-bit touch event is a touch event received in a bit period associated with a one bit;

count a number of zero-bit touch events, wherein a zero-bit touch event is a touch event received in a bit period associated with a zero bit;

calculate a ratio of the number of one-bit touch events to the number of zero-bit touch events; and

select a starting point that results in the ratio being maximized; and

determine a touch event threshold based on the sequence of touch events, wherein the touch event threshold is the number of touch events that is least likely to occur in a bit period associated with either a zero bit or a one bit.

23. The system according to claim 17, wherein the instructions further cause the processor to:

receiving, by the electronic device, a sequence of touch events generated in response to the to the modulated signal;

identifying a plurality of bit period sequences each having a unique starting position, and each bit period sequence comprising a plurality of bit periods;

for each bit period sequence, counting the number of events in each bit period;

generating a bit sequence for each bit period sequence by;

on a condition that the number of touch events is greater than a threshold, identifying the bit period as a one bit; and

on a condition that the number of touch events is less than a threshold, identifying the bit period as a zero bit;

comparing each bit sequence to a table of possible messages; and

selecting a message from the table that is most similar to the bit sequence.