Time interval measurement for capacitive detection

• US 7,797,115 B2
• Filed: 08/13/2007
• Issued: 09/14/2010
• Est. Priority Date: 08/13/2007
• Status: Active Grant

• Current Assignee: Nuvoton Technology Corporation (Winbond Electronics Corporation)
• Original Assignee: Nuvoton Technology Corporation (Winbond Electronics Corporation)
• Inventors: Tasher, Nir, Friedman, Yehezkel, Abramov, Vladimir
• Primary Examiner(s): Cosimano; Edward R
• Application Number:
  US11/889,435
• Publication Number:
  US 20090046827A1
• Time in Patent Office: 1,128 Days
• Field of Search: 178/18.06, 178/2.R, 178/18.01, 178/18.03, 324/600, 324/649, 324/658, 324/661, 324/663, 324/672, 324/679, 324/686, 341/33, 341/20, 341/22, 702/89, 702/116, 702/125, 702/1, 702/57, 702/79, 702/85, 702/104, 702/108, 702/124, 702/127, 702/150, 702/179, 702/189, 345/156, 345/173, 368/89, 368/107, 377/1, 377/13, 377/16, 377/19, 377/20
• US Class Current: 702/57
• CPC Class Codes: G01D 5/2405 by varying dielectric
• CPC Class Codes: 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
• CPC Class Codes: G06F 3/0443 using a single layer of sensing electrodes

Abstract

Capacitive detection systems, modules, and methods. In one embodiment, time interval measurement(s) are generated that are monotonic functions of the capacitance(s) of capacitive sensor(s) in a capacitive sensing area. In one embodiment, the generated time interval measurement(s), or any other monotonic function(s) of capacitance(s) of capacitive sensor(s) in a capacitive sensing area, may be analyzed to detect the presence of an object near the capacitive sensing area and/or to detect the position of an object near the capacitive sensing area.

Claims

1. A method of generating a time interval measurement which is a monotonic function of the capacitance of a capacitive sensor, comprising:

causing a voltage across a capacitive sensor to change at least one time;

generating a time interval measurement which is a monotonic function of capacitance of said capacitive sensor by measuring at least one time interval during each of which said changing voltage across said sensor ranges between two predetermined values, wherein if said time interval measurement is generated by measuring at least two time intervals then said measuring is cumulative, and wherein said predetermined values corresponding to at least one of said at least one time interval are both non-zero; and

analyzing said generated time interval measurement in order to detect or not detect presence of an object near said capacitive sensor.

2. A module for generating a time interval measurement which is a monotonic function of the capacitance of a capacitive sensor, comprising:

a means for causing a voltage across a capacitive sensor to change at least one time;

a means for generating a time interval measurement which is a monotonic function of capacitance of said capacitive sensor, including a means for measuring a time interval during which said changing voltage across said sensor ranges between two predetermined values or a means for cumulatively measuring at least two time intervals during each of which said changing voltage across said sensor ranges between two predetermined values, wherein said predetermined values corresponding to at least one measured time interval are both non-zero; and

a clock generator configured to generate a clock signal, wherein said clock generator is configured to selectively provide a jitter in said generated clock signal.

3. The method of claim 2, wherein said means for generating includes a counter, and wherein said generated clock signal or a function thereof is provided to said counter.

4. A module for generating a time interval measurement which is a monotonic function of the capacitance of a capacitive sensor, comprising:

a means for causing a voltage across a capacitive sensor to change at least one time;

a means for generating a time interval measurement which is a monotonic function of capacitance of said capacitive sensor, including a means for measuring a time interval during which said changing voltage across said sensor ranges between two predetermined values or a means for cumulatively measuring at least two time intervals during each of which said changing voltage across said sensor ranges between two predetermined values, wherein said predetermined values corresponding to at least one measured time interval are both non-zero; and

a controller configured to configure at least one operational parameter affecting operation of said module.

5. A module for generating a time interval measurement which is a monotonic function of the capacitance of a capacitive sensor, comprising:

a means for causing a voltage across a capacitive sensor to change at least one time;

a means for generating a time interval measurement which is a monotonic function of capacitance of said capacitive sensor, including a means for measuring a time interval during which said changing voltage across said sensor ranges between two predetermined values or a means for cumulatively measuring at least two time intervals during each of which said changing voltage across said sensor ranges between two predetermined values, wherein said predetermined values corresponding to at least one measured time interval are both non-zero; and

a controller configured to receive said generated time interval measurement and to analyze said generated time interval measurement to detect or not detect presence of an object near said sensor.

6. A capacitive detection method comprising:

causing each voltage across at least one capacitive sensor in a capacitive sensing area to change at least one time;

for each of said at least one capacitive sensor, generating a time interval measurement which is a monotonic function of capacitance of said capacitive sensor by measuring at least one time interval during each of which said changing voltage across said sensor ranges between two non-zero predetermined values, wherein if said time interval measurement is generated by measuring at least two time intervals then said measuring is cumulative; and

analyzing said at least one generated time interval measurement corresponding to said at least one capacitive sensor in order to detect or not detect presence of an object near said capacitive sensing area.

7. The method of claim 6, wherein said at least one capacitive sensor includes at least two capacitive sensors, further comprising:

if presence was detected, analyzing generated time interval measurements for said at least two capacitive sensors in order to detect position of said object.

8. A capacitive detection system, comprising:

a capacitive sensing area comprising at least one capacitive sensor, a capacitive gauging module configured to cause each voltage across at least one sensor in said capacitive sensing area to change at least one time and configured to generate for each of said at least one sensor whose voltage was caused to change, a time interval measurement which is a monotonic function of capacitance of said capacitive sensor, said gauging module including at least one counter, wherein each counter corresponds to one sensor and is configured to measure a time interval during which said changing voltage across said corresponding sensor ranges between two non-zero predetermined values or configured to cumulatively measure at least two time intervals during each of which said changing voltage across said corresponding sensor ranges between two non-zero predetermined values; and

a controller module configured to analyze said at least one generated time interval measurement corresponding to said at least one sensor whose at least one voltage was caused to change in order to detect or not detect presence of an object near said capacitive sensing area.

9. The system of claim 8, wherein said at least one capacitive sensor includes at least two capacitive sensors, said controller is further configured to analyze generated time interval measurements for said at least two capacitive sensors in order to detect position of an object whose presence was detected.