Capacitive sensing and data input device power management
First Claim
1. A capacitive sensing system for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising:
- a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor;
a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor;
an input threshold switch;
switching means for selectively;
connecting at least one of said scoop capacitor and bucket capacitor to a voltage source to charge said at least one capacitor, varying the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, said varying being carried out for plural cycles of charge transfer to or from said scoop capacitor, and applying a voltage of said bucket capacitor to said input threshold switch;
detector means for detecting an input state of said input threshold switch;
determining means for determining a value (TouchVal) based upon a count of a number of said cycles of charge transfer corresponding to a detection of a transition of said input threshold switch by said detector means; and
signal generating means for generating, based upon TouchVal, a signal indicative of an ON state wherein said object or body portion is in contact with or close proximity to said another object, and an OFF state wherein said object or body portion is not in contact with or close proximity to said another object.
2 Assignments
0 Petitions
Accused Products
Abstract
Capacitive proximity sensing is carried out by detecting a relative change in the capacitance of a “scoop” capacitor formed by a conductor and a surrounding ground plane. The conductor may be a plate provided in the form of an adhesive label printed with conductive ink. Charge is transferred between the “scoop” capacitor and a relatively large “bucket” capacitor, and a voltage of the bucket capacitor is applied to an input threshold switch. A state transition (e.g., from low to high, or high to low) of the input threshold switch is detected and a value (TouchVal) indicative of a number of cycles of charge transfer required to reach the state transition is determined. The presence or absence of an object or body portion in close proximity to or contact with a device can be determined by comparing TouchVal with a predetermined threshold value (TouchOff). TouchOff can be adjusted to take into account environmentally induced (non-touch related) changes in the capacitance of the scoop capacitor. Power management is provided in a user operated data input device utilizing proximity sensing and switching between three or more power states. Switching between the power states occurs based upon the presence or absence of input activity, and an operation instrumentality (e.g., a hand) in close proximity to or contact with the device. In an optical surface tracking cursor control device embodiment, switching to and from a BEACON state, which provides a reduced flash rate of a surface illuminating light source, is carried out based upon a detected presence or absence of a trackable surface.
261 Citations
52 Claims
-
1. A capacitive sensing system for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising:
-
a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor;
a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor;
an input threshold switch;
switching means for selectively;
connecting at least one of said scoop capacitor and bucket capacitor to a voltage source to charge said at least one capacitor, varying the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, said varying being carried out for plural cycles of charge transfer to or from said scoop capacitor, and applying a voltage of said bucket capacitor to said input threshold switch;
detector means for detecting an input state of said input threshold switch;
determining means for determining a value (TouchVal) based upon a count of a number of said cycles of charge transfer corresponding to a detection of a transition of said input threshold switch by said detector means; and
signal generating means for generating, based upon TouchVal, a signal indicative of an ON state wherein said object or body portion is in contact with or close proximity to said another object, and an OFF state wherein said object or body portion is not in contact with or close proximity to said another object. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27)
said switching means cyclically;
(a) clamps the first and second terminals to ground, to discharge the bucket capacitor;
(b) sets the second terminal to be a high impedance input and drives the first terminal, to charge the scoop capacitor without charging the bucket capacitor; and
(c) sets the first terminal to be a high impedance input and drives the second terminal, to transfer charge from the scoop capacitor to the bucket capacitor;
said input threshold switch is connected to one of said first terminal and said second terminal to receive a voltage therefrom when said one terminal is set to be said high impedance input; and
said detector means samples, in relation to the cycling of said switching means, a state of said input threshold switch.
-
-
4. A capacitive sensing system according to claim 1, wherein the at least one capacitor comprises said bucket capacitor and said varying of the charge of said bucket capacitor comprises transferring charge from said bucket capacitor to said scoop capacitor.
-
5. A capacitive sensing system according to claim 4, conductor of said scoop capacitor being commonly connected, together with a first one of said pair of conductors of said bucket capacitor, to a first terminal, the second of said pair of conductors of the bucket capacitor being connected to a second terminal, wherein:
-
said switching means cyclically;
(a) drives the first terminal high and drives the second terminal low, to charge the bucket capacitor;
(b) sets the second terminal to be a high impedance input and drives the first terminal low, to discharge the scoop capacitor without discharging the bucket capacitor, and (c) sets the first terminal to be a high impedance input and drives the second terminal to transfer charge from the bucket capacitor to the scoop capacitor;
said input threshold switch is connected to one of said first terminal and said second terminal to receive a voltage therefrom when said one terminal is set to be said high impedance input; and
said detector means samples, in relation to the cycling of said switching means, a state of said input threshold switch.
-
-
6. A capacitive sensing system according to claim 1, wherein the at least one capacitor comprises said scoop capacitor and said bucket capacitor connected in series, and said varying of the charge of said bucket capacitor comprises charging said bucket capacitor with said voltage source, as regulated by said scoop capacitor.
-
7. A capacitive sensing system according to claim 6, first conductor of said scoop capacitor being commonly connected, together with a first one of said pair of conductors of said bucket capacitor, to a first terminal, the second of said pair of conductors of the bucket capacitor being connected to a second terminal, wherein:
-
said switching means cyclically;
(a) drives the first and second terminals low, to discharge the bucket capacitor and scoop capacitor;
(b) sets the first terminal to be a high impedance input and drives the second terminal high, to place the bucket capacitor and scoop capacitor in series, and (c) sets the second terminal to be a high impedance input and drives the first terminal low, to discharge the scoop capacitor without discharging the bucket capacitor;
said input threshold switch is connected to one of said first terminal and said second terminal to receive a voltage therefrom when said one terminal is set to be said high impedance input; and
said detector means samples, in relation to the cycling of said switching means, a state of said input threshold switch.
-
-
8. A capacitive sensing system according to claim 1, further comprising comparing means for comparing TouchVal, or a number derived from TouchVal, with a predetermined threshold value (TouchOff), or a number derived from TouchOff and wherein said signal generating means generates said ON and OFF state indicating signals based upon an output of said comparing means.
-
9. A capacitive sensing system according to claim 8, comprising means for deriving a value (Touch Avg) from TouchVal, said comparing means comparing TouchAvg with TouchOff during said ON state.
-
10. A capacitive sensing system according to claim 8, wherein said signal generating means transitions from said OFF state to said ON state upon TouchVal decreasing below TouchOff by a predetermined amount.
-
11. A capacitive sensing system according to claim 8, said system decrementing Touch Off upon TouchVal remaining below TouchOff for a predetermined interval.
-
12. A capacitive sensing system according to claim 8, further comprising threshold count determining means for dynamically adjusting the value of TouchOff in accordance with a relative decrease in the capacitance of said scoop capacitor occurring during said OFF state.
-
13. A capacitive sensing system according to claim 12, further comprising means for deriving a value (Touch Avg) from TouchVal, said comparing means comparing TouchAvg with TouchOff during said ON state.
-
14. A capacitive sensing system according to claim 13, wherein TouchAvg is initially set to equal TouchVal upon a transition from the OFF state to the ON state, and the value of TouchAvg is incremented upon TouchVal exceeding TouchAvg for a predetermined interval.
-
15. A capacitive sensing system according to claim 12, wherein said decrease in the capacitance of said scoop capacitor is determined from the occurrence of an increase in TouchVal during said OFF state.
-
16. A capacitive sensing system according to claim 15, wherein said decrease in the capacitance of said scoop capacitor is determined from TouchVal remaining above TouchOff for a predetermined interval.
-
17. A capacitive sensing system according to claim 1, wherein said object is a computer peripheral device, and said first conductor is mounted on said computer peripheral device.
-
18. A capacitive sensing system according to claim 17, wherein said computer peripheral device is an external computer peripheral device linkable to a separate host computer, said peripheral device incorporating therein a power supply.
-
19. A capacitive sensing system according to claim 18, wherein said external computer peripheral device is linkable to a host computer without a hard-wired connection.
-
20. A capacitive sensing system according to claim 19, wherein said external computer peripheral device is a cursor control device comprising an optical tracking engine.
-
21. A capacitive sensing system according to claim 20, wherein said cursor control device is a computer mouse configured to track on a planar surface upon which the mouse rests.
-
22. A capacitive sensing system according to claim 1, wherein TouchVal for a control cycle n is a moving average value.
-
23. A capacitive sensing system according to claim 1, wherein said input threshold switch comprises a CMOS transistor.
-
24. A capacitive sensing system according to claim 1, wherein said input threshold switch, said switching means, said detector means, said determining means and said signal generating means are provided within a control integrated circuit (IC) having a pair of pins, said first conductor of said scoop capacitor being commonly connected, together with a first one of said pair of conductors of said bucket capacitor, to a first one of said pair of pins, the second of said pair of conductors of the bucket capacitor being connected to the second of said pair of pins.
-
25. A capacitive sensing system according to claim 24, wherein:
-
said switching means cyclically;
(a) clamps the first and second pins to ground, to discharge the bucket capacitor;
(b) sets the second pin to be a high impedance input and drives the first pin to charge the scoop capacitor without charging the bucket capacitor; and
(c) sets the first pin to be a high impedance input and drives the second pin, to transfer charge of the scoop capacitor to the bucket capacitor;
said input threshold switch is connected to one of said first pin and said second pin to receive a voltage therefrom when said one pin is set to be said high impedance input; and
said detector means samples, in relation to the cycling of said switching means, a state of said input threshold switch.
-
-
26. A capacitive sensing system according to claim 24, wherein:
-
said switching means cyclically;
(a) drives the first pin high and drives the second pin low, to charge the bucket capacitor;
(b) sets the second pin to be a high impedance input and drives the first pin low, to discharge the scoop capacitor without discharging the bucket capacitor; and
(c) sets said first pin to be a high impedance input and drives the second pin, to transfer charge from the bucket capacitor to the scoop capacitor;
said input threshold switch is connected to one of said first pin and said second pin to receive a voltage therefrom when said one pin is set to be said high impedance input; and
said detector means samples, in relation to the cycling of said switching means, a state of said input threshold switch.
-
-
27. A capacitive sensing system according to claim 24, wherein:
-
said switching means cyclically;
(a) drives the first and second pins low, to discharge the bucket capacitor and scoop capacitor;
(b) sets the first pin to be a high impedance input and drives the second pin high, to place the bucket capacitor and scoop capacitor in series; and
(c) sets said second pin to be a high impedance input and drives the first pin low, to discharge the scoop capacitor without discharging the bucket capacitor;
said input threshold switch is connected to one of said first pin and said second pin to receive a voltage therefrom when said one pin is set to be said high impedance input; and
said detector means samples, in relation to the cycling of said switching means, a state of said input threshold switch.
-
-
28. A method for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising:
-
providing a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor;
a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor; and
an input threshold switch;
performing switching to selectively;
connect at least one of said scoop capacitor and said bucket capacitor to a voltage source to charge said at least one capacitor, vary the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, said varying being carried out for plural cycles of charge transfer to or from said scoop capacitor, and apply a voltage of said bucket capacitor to said input threshold switch;
detecting an input state of said input threshold switch;
determining a value (TouchVal) relating to a number of said cycles of charge transfer corresponding to a detection of a transition of said input threshold switch; and
generating, based upon TouchVal, a signal indicative of an ON state wherein said object or body portion is in contact with or close proximity to said another object, and an OFF state wherein said object or body portion is not in contact with or close proximity to said object. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44)
said first conductor of said scoop capacitor is commonly connected, together with a first one of said pair of conductors of said bucket capacitor, to a first terminal, the second of said pair of conductors of the bucket capacitor being connected to a second terminal;
said switching cyclically;
(a) clamps the first and second terminals to ground, to discharge the bucket capacitor;
(b) sets the second terminal to be a high impedance input and drives the first terminal to charge the scoop capacitor without charging the bucket capacitor, said input threshold switch being connected to one of said first terminal and said second terminal to receive a voltage therefrom when said one terminal is set to be said high impedance input; and
(c) sets the first terminal to be a high impedance input and drives the second terminal, to transfer charge of the scoop capacitor to the bucket capacitor; and
said detecting comprises sampling, in relation to the cycling through steps (a)-(c), a state of said input threshold switch.
-
-
31. A method for sensing according to claim 28, wherein the at least one capacitor comprises said bucket capacitor, and said varying of the charge of said bucket capacitor comprises transferring charge from said bucket capacitor to said scoop capacitor.
-
32. A method for sensing according to claim 31, wherein:
-
said first conductor of said scoop capacitor is commonly connected, together with a first one of said pair of conductors of said bucket capacitor, to a first terminal, the second of said pair of conductors of the bucket capacitor being connected to a second terminal;
said switching cyclically;
(a) drives the first terminal high and drives the second terminal low, to charge the bucket capacitor;
(b) sets the second terminal to be a high impedance input and drives the first terminal low to discharge the scoop capacitor without discharging the bucket capacitor; and
(c) sets said first terminal to be a high impedance input and drives the second terminal, to transfer charge from the bucket capacitor to the scoop capacitor, said input threshold switch being connected to one of said first terminal and said second terminal to receive a voltage therefrom when said one terminal is set to be said high impedance input; and
said detecting comprises sampling, in relation to the cycling through steps (a)-(c), a state of said input threshold switch.
-
-
33. A method for sensing according to claim 28, wherein the at least one said scoop capacitor and said bucket capacitor connected in series, and said varying of the charge of said bucket capacitor comprises charging said bucket capacitor with said voltage source, as regulated by said scoop capacitor.
-
34. A method for sensing according to claim 33, wherein:
-
said first conductor of said scoop capacitor is commonly connected, together with a first one of said pair of conductors of said bucket capacitor, to a first terminal, the second of said pair of conductors of the bucket capacitor being connected to a second terminal;
said switching cyclically;
(a) drives the first and second terminals low, to discharge the bucket capacitor and scoop capacitor;
(b) sets the first terminal to be a high impedance input and drives the second terminal high, to place the bucket capacitor and scoop capacitor in series; and
(c) sets said second terminal to be a high impedance input and drives the first terminal low, to discharge the scoop capacitor without discharging the bucket capacitor, said input threshold switch being connected to one of said first terminal and said second terminal to receive a voltage therefrom when said one terminal is set to be said high impedance input; and
said detecting comprises sampling, in relation to the cycling through steps (a)-(c), a state of said input threshold switch.
-
-
35. A method for sensing according to claim 28, further comprising comparing TouchVal, or a number derived from Touch Val, with a predetermined threshold value (TouchOff), or a number derived from TouchOff and wherein said signal generating generates said ON and OFF state indicating signals based upon an output of said comparing.
-
36. A method for sensing according to claim 35, further comprising dynamically adjusting the value of TouchOff in accordance with a relative decrease in the capacitance of said scoop capacitor occurring during said OFF state.
-
37. A method for sensing according to claim 36, further comprising deriving a value (Touch Avg) from TouchVal, wherein said comparing compares TouchAvg with TouchOff during said ON state.
-
38. A method for sensing according to claim 37, wherein TouchAvg is initially set to equal TouchVal upon a transition from the OFF state to the ON state, and the value of TouchAvg is incremented upon TouchVal exceeding TouchAvg for a predetermined interval.
-
39. A method for sensing according to claim 38, wherein said decrease in the capacitance of said scoop capacitor is determined from the occurrence of an increase in Touch Val during said OFF state.
-
40. A method for sensing according to claim 39, wherein said decrease in the capacitance of said scoop capacitor is determined from TouchVal remaining above TouchOff for a predetermined interval.
-
41. A method for sensing according to claim 28, wherein Touch Val for a control cycle n is a moving average value.
-
42. A method for sensing according to claim 35, further comprising deriving a value (Touch Avg) from TouchVal, wherein said comparing compares TouchAvg with TouchOff during said ON state.
-
43. A method for sensing according to claim 35, wherein in said signal generating, a transition from said OFF state to said ON state occurs upon TouchVal decreasing below TouchOff by a predetermined amount.
-
44. A method according to claim 35, wherein TouchOff is decremented upon TouchVal remaining below TouchOff for a predetermined interval.
-
45. A capacitive sensing system for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising:
-
a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor;
a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor;
an input threshold switch;
switching means for selectively;
connecting at least one of said scoop capacitor and bucket capacitor to a voltage source to charge said at least one capacitor, varying the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, and applying a voltage of said bucket capacitor to said input threshold switch;
detector means for detecting an input state of said input threshold switch;
determining means for determining a value (TouchVal) relating to a number of cycles of said varying of the bucket capacitor charge, corresponding to a detection of a transition of said input threshold switch by said detector means;
signal generating means for generating, based upon TouchVal, a signal indicative of an ON state wherein said object or body portion is in contact with or close proximity to said another object, and an OFF state wherein said object or body portion is not in contact with or close proximity to said another object;
comparing means for comparing TouchVal, or a number derived from TouchVal, with a predetermined threshold value (TouchOff), or a number derived from TouchOff; and
wherein said signal generating means generates said ON and OFF state indicating signals based upon an output of said comparing means; and
threshold count determining means for dynamically adjusting the value of TouchOff in accordance with a relative decrease in the capacitance of said scoop capacitor occurring during said OFF state.
-
-
46. A capacitive sensing system for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising:
-
a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor;
a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor;
an input threshold switch;
switching means for selectively;
connecting at least one of said scoop capacitor and bucket capacitor to a voltage source to charge said at least one capacitor, varying the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, and applying a voltage of said bucket capacitor to said input threshold switch;
detector means for detecting an input state of said input threshold switch;
determining means for determining a value (TouchVal) relating to a number of cycles of said varying of the bucket capacitor charge, corresponding to a detection of a transition of said input threshold switch by said detector means;
signal generating means for generating, based upon TouchVal, a signal indicative of an ON state wherein said object or body portion is in contact with or close proximity to said another object, and an OFF state wherein said object or body portion is not in contact with or close proximity to said another object;
comparing means for comparing TouchVal, or a number derived from TouchVal, with a predetermined threshold value (TouchOff), or a number derived from TouchOff; and
wherein said signal generating means generates said ON and OFF state indicating signals based upon an output of said comparing means; and
means for deriving a value (Touch Avg) from TouchVal, said comparing means comparing TouchAvg with TouchOff during said ON state.
-
-
47. A capacitive sensing system for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising:
-
a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor;
a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor;
an input threshold switch;
switching means for selectively;
connecting at least one of said scoop capacitor and bucket capacitor to a voltage source to charge said at least one capacitor, varying the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, and applying a voltage of said bucket capacitor to said input threshold switch;
detector means for detecting an input state of said input threshold switch;
determining means for determining a value (TouchVal) relating to a number of cycles of said varying of the bucket capacitor charge, corresponding to a detection of a transition of said input threshold switch by said detector means;
signal generating means for generating, based upon TouchVal, a signal indicative of an ON state wherein said object or body portion is in contact with or close proximity to said another object, and an OFF state wherein said object or body portion is not in contact with or close proximity to said another object; and
comparing means for comparing TouchVal, or a number derived from TouchVal, with a predetermined threshold value (TouchOff), or a number derived from TouchOff and wherein said signal generating means generates said ON and OFF state indicating signals based upon an output of said comparing means, wherein said signal generating means transitions from said OFF state to said ON state upon Touch Val decreasing below TouchOff by a predetermined amount.
-
-
48. A capacitive sensing system for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising:
-
a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor;
a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor;
an input threshold switch;
switching means for selectively;
connecting at least one of said scoop capacitor and bucket capacitor to a voltage source to charge said at least one capacitor, varying the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, and applying a voltage of said bucket capacitor to said input threshold switch;
detector means for detecting an input state of said input threshold switch;
determining means for determining a value (TouchVal) relating to a number of cycles of said varying of the bucket capacitor charge, corresponding to a detection of a transition of said input threshold switch by said detector means;
signal generating means for generating, based upon TouchVal, a signal indicative of an ON state wherein said object or body portion is in contact with or close proximity to said another object, and an OFF state wherein said object or body portion is not in contact with or close proximity to said another object; and
comparing means for comparing TouchVal, or a number derived from TouchVal, with a predetermined threshold value (TouchOff), or a number derived from TouchOff; and
wherein said signal generating means generates said ON and OFF state indicating signals based upon an output of said comparing means, said system decrementing Touch Off upon TouchVal remaining below TouchOff for a predetermined interval.
-
-
49. A method for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising:
-
providing a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor;
a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor; and
an input threshold switch;
performing switching to selectively;
connect at least one of said scoop capacitor and said bucket capacitor to a voltage source to charge said at least one capacitor, vary the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, and apply a voltage of said bucket capacitor to said input threshold switch;
detecting an input state of said input threshold switch;
determining a value (TouchVal) relating to a number of cycles of said varying of the bucket capacitor charge, corresponding to a detection of a transition of said input threshold switch;
generating, based upon TouchVal, a signal indicative of an ON state wherein said object or body portion is in contact with or close proximity to said another object, and an OFF state wherein said object or body portion is not in contact with or close proximity to said object;
comparing TouchVal, or a number derived from TouchVal, with a predetermined threshold value (TouchOff), or a number derived from TouchOff and wherein said signal generating generates said ON and OFF state indicating signals based upon an output of said comparing; and
dynamically adjusting the value of TouchOff in accordance with a relative decrease in the capacitance of said scoop capacitor occurring during said OFF state.
-
-
50. A method for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising:
-
providing a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor;
a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor; and
an input threshold switch;
performing switching to selectively;
connect at least one of said scoop capacitor and said bucket capacitor to a voltage source to charge said at least one capacitor, vary the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, and apply a voltage of said bucket capacitor to said input threshold switch;
detecting an input state of said input threshold switch;
determining a value (TouchVal) relating to a number of cycles of said varying of the bucket capacitor charge, corresponding to a detection of a transition of said input threshold switch; and
generating, based upon TouchVal, a signal indicative of an ON state wherein said object or body portion is in contact with or close proximity to said another object, and an OFF state wherein said object or body portion is not in contact with or close proximity to said object;
comparing TouchVal, or a number derived from TouchVal, with a predetermined threshold value (TouchOff), or a number derived from TouchOff; and
wherein said signal generating generates said ON and OFF state indicating signals based upon an output of said comparing; and
deriving a value (Touch Avg) from TouchVal, wherein said comparing compares TouchAvg with TouchOff during said ON state.
-
-
51. A method for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising:
-
providing a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor;
a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor; and
an input threshold switch;
performing switching to selectively;
connect at least one of said scoop capacitor and said bucket capacitor to a voltage source to charge said at least one capacitor, vary the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, and apply a voltage of said bucket capacitor to said input threshold switch;
detecting an input state of said input threshold switch;
determining a value (TouchVal) relating to a number of cycles of said varying of the bucket capacitor charge, corresponding to a detection of a transition of said input threshold switch;
generating, based upon TouchVal, a signal indicative of an ON state wherein said object portion is in contact with or close proximity to said another object, and an OFF state wherein said object or body portion is not in contact with or close proximity to said object; and
comparing TouchVal, or a number derived from TouchVal, with a predetermined threshold value (TouchOff), or a number derived from TouchOff and wherein said signal generating generates said ON and OFF state indicating signals based upon an output of said comparing, wherein in said signal generating, a transition from said OFF state to said ON state occurs upon Touch Val decreasing below TouchOff by a predetermined amount.
-
-
52. A method for sensing the presence of an object or body portion in contact with or close proximity to another object, comprising:
-
providing a first conductor capacitively coupled to a ground to thereby form a scoop capacitor having a capacitance which varies in relation to the proximity of said object or body portion to said conductor;
a pair of second and third conductors forming a bucket capacitor having a capacitance which is larger than a maximum capacitance of said scoop capacitor; and
an input threshold switch;
performing switching to selectively;
connect at least one of said scoop capacitor and said bucket capacitor to a voltage source to charge said at least one capacitor, vary the charge of said bucket capacitor in relation to a relative size of said scoop capacitor, and apply a voltage of said bucket capacitor to said input threshold switch;
detecting an input state of said input threshold switch;
determining a value (TouchVal) relating to a number cycles of said varying of the bucket capacitor charge, corresponding to a detection of a transition of said input threshold switch; and
generating, based upon TouchVal, a signal indicative of an ON state wherein said object or body portion is in contact with or close proximity to said object; and
comparing TouchVal, or a number derived from TouchVal, with a predetermined threshold value (TouchOff), or a number derived from TouchOff; and
wherein said signal generating generates said ON and OFF state indicating signals based upon an output of said comparing, wherein TouchOff is decremented upon TouchVal remaining below TouchOff for a predetermined interval.
-
Specification