Method and device for dual-differential sensing

• US 20110084930A1
• Filed: 10/08/2010
• Published: 04/14/2011
• Est. Priority Date: 10/09/2009
• Status: Active Grant

• Current Assignee: eGalax_eMPIA Technology Inc.
• Original Assignee: eGalax_eMPIA Technology Inc.
• Inventors: Lee, Cheng-Han, Ho, Shun-Lung, Tang, Chi-Hao, Chang, Chin-Fu
• Granted Patent: US 8,643,613 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G01R 27/2605 Measuring capacitance capacitive sensors G01D5/24
• CPC Class Codes: G06F 2203/04102 Flexible digitiser, i.e. constructional details for allowing the whole digitising part of a device to be flexed or rolled like a sheet of paper
• CPC Class Codes: G06F 2203/04103 Manufacturing, i.e. details related to manufacturing processes specially suited for touch sensitive devices
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 2203/04111 Cross over in capacitive digitiser, i.e. details of structures for connecting electrodes of the sensing pattern where the connections cross each other, e.g. bridge structures comprising an insulating layer, or vias through substrate
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• 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 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/047 using sets of wires, e.g. crossed wires

Abstract

A method and device for dual-differential sensing is disclosed. The sensing information can be generated from signals provided by a sensing device with a plurality of sensors. Each value of the sensing information corresponds to signals of three sensors, respectively. The sensing device is flexible and configured on a display. The noise effect of the display on the signal of each sensor corresponds to the distance between the display and the sensor. Besides, the noise effect of the display on each value of the sensing information corresponds to the distances between the display and the three sensors, respectively.

Claims

1. A dual-differential sensing method, comprising:

providing a sensing device including a plurality of sensors;

obtaining a sensing information, each value of the sensing information corresponding to signals of three sensors in the sensors; and

determining a location on the sensing device touched or approached by an external object according to the sensing information.

2. The method of claim 1, further comprising:

providing a dual-differential circuit, including;

a first-stage differential circuit including a pair or a plurality of first subtractors, each of the first subtractors generating a first-stage differential signal based on signals of a pair of sensors in the sensors;

a second-stage differential circuit including one or a plurality of second subtractors, each of the second subtractors generating a second-stage differential signal based on a pair of the first-stage differential signals in the first-stage differential signals; and

a measuring circuit for measuring the second-stage differential signals at one or a plurality of time points to generate the sensing information.

3. The method of claim 2, wherein each value of the sensing information is generated from one of the second-stage differential signals, and each of the second-stage differential signals is generated from a first differential signal and a second differential signal of the pair of the first-stage differential signals, wherein the first differential signal is generated based on signals of a first sensor and a second sensor of the sensors, and the second differential signal is generated based on signals of the second sensor and a third sensor of the sensors.

4. The method of claim 1, further comprising:

providing a differential circuit, including;

one or a plurality of subtractors, each subtractor generating a differential signal based on signals of a pair of sensors in the sensors; and

a measuring circuit for measuring the differential signals at one or a plurality of time points to generate a differential sensing information; and

generating the sensing information based on the differential sensing information, wherein each value of the sensing information is generated from a pair of values of the differential sensing information.

5. The method of claim 4, wherein each value of the sensing information is the difference between a pair of values of the differential sensing information.

6. The method of claim 4, wherein each value of the sensing information is the difference between a first difference and a second difference of the differential sensing information, wherein the first difference is generated based on signals of a first sensor and a second sensor of the sensors, and the second difference is generated based on signals of the second sensor and a third sensor of the sensors.

7. The method of claim 1, further comprising:

providing a measuring circuit for measuring signals of the sensors at one or a plurality of time points to generate an initial sensing information; and

generating the sensing information based on the initial sensing information, wherein each value of the sensing information is generated from three values of the initial sensing information.

8. The method of claim 7, wherein each value of the sensing information is the difference or sum of a first difference and a second difference, wherein the first difference is the difference of the prior two values of three values of the initial sensing information, and the second difference is the difference of the latter two values of the three values of the initial sensing information.

9. The method of claim 7, wherein the three values of the initial sensing information are a first value, a second value, and a third value, respectively, and each value of the sensing information is (the second value−

the first value)−

(the third value−

the second value), (the first value−

the second value)−

(the second value−

the third value), (the second value−

the first value)+(the second value−

the third value), or (the first value−

the second value)+(the third value−

the second value).

10. The method of claim 7, wherein each touch related sensing information in the sensing information has two zero-crossings, and the location touched or approached by the external object is determined based on each touch related sensing information.

11. A dual-differential sensing device, comprising:

a sensing device including a plurality of sensors; and

a controller for obtaining a sensing information, each value of the sensing information corresponding to signals of three sensors in the sensors.

12. The device of claim 11, further comprising:

a dual-differential circuit, including;

a first-stage differential circuit including a pair or a plurality of first subtractors, each of the first subtractors generating a first-stage differential signal based on signals of a pair of sensors in the sensors;

a second-stage differential circuit including one or a plurality of second subtractors, each of the second subtractors generating a second-stage differential signal based on a pair of the first-stage differential signals in the first-stage differential signals; and

a measuring circuit for measuring the second-stage differential signals at one or a plurality of time points to generate the sensing information.

13. The device of claim 12, wherein each value of the sensing information is generated from one of the second-stage differential signals, and each of the second-stage differential signals is generated from a first differential signal and a second differential signal of the pair of the first-stage differential signals, wherein the first differential signal is generated based on signals of a first sensor and a second sensor of the sensors, and the second differential signal is generated based on signals of the second sensor and a third sensor of the sensors.

14. The device of claim 11, further comprising:

a differential circuit, including;

one or a plurality of subtractors, each subtractor generating a differential signal based on signals of a pair of sensors in the sensors; and

a measuring circuit for measuring the differential signals at one or a plurality of time points to generate a differential sensing information; and

wherein the controller generates the sensing information based on the differential sensing information, wherein each value of the sensing information is generated from a pair of values of the differential sensing information.

15. The device of claim 14, wherein each value of the sensing information is the difference between a pair of values of the differential sensing information.

16. The device of claim 14, wherein each value of the sensing information is the difference between a first difference and a second difference of the differential sensing information, wherein the first difference is generated based on signals of a first sensor and a second sensor of the sensors, and the second difference is generated based on signals of the second sensor and a third sensor of the sensors.

17. The device of claim 11, further comprising:

a measuring circuit for measuring signals of the sensors at one or a plurality of time points to generate an initial sensing information; and

wherein the controller generates the sensing information based on the initial sensing information, wherein each value of the sensing information is generated from three values of the initial sensing information.

18. The device of claim 17, wherein each value of the sensing information is the difference or sum of a first difference and a second difference, wherein the first difference is the difference of the prior two values of three values of the initial sensing information, and the second difference is the difference of the latter two values of the three values of the initial sensing information.

19. The device of claim 17, wherein the three values of the initial sensing information are a first value, a second value, and a third value, respectively, and each value of the sensing information is (the second value−

the first value)−

(the third value−

the second value), (the first value−

the second value)−

(the second value−

the third value), (the second value−

the first value)+(the second value−

the third value), or (the first value−

the second value)+(the third value−

the second value).

20. The device of claim 17, wherein the three values are adjacent or non-adjacent.

21. The device of claim 11, wherein each touch related sensing information in the sensing information has two zero-crossings, and the location touched or approached by the external object is determined based on each touch related sensing information.