Methods and systems for detecting a capacitance using sigma-delta measurement techniques
First Claim
1. A method for measuring a measurable capacitance, the method comprising the steps of:
- applying a voltage to the measurable capacitance using a first switch;
allowing the measurable capacitance to share charge with a passive network;
changing a charge on the passive network by an amount of charge if the charge on the passive network is past a threshold; and
repeating each of the applying step, the allowing step, and the changing step at least once.
3 Assignments
0 Petitions
Accused Products
Abstract
Methods, systems and devices are described for detecting a measurable capacitance using sigma-delta measurement techniques. According to various embodiments, a voltage is applied to the measurable capacitance using a first switch. The measurable capacitance is allowed to share charge with a passive network. If the charge on the passive network is past a threshold value, then the charge on the passive network is changed by a known amount for a sufficient number of repetitions until the measurable capacitance can be detected. Such a detection scheme may be readily implemented using conventional components, and can be particularly useful in sensing the position of a finger, stylus or other object with respect to a button, slider, touchpad or other input sensor.
-
Citations
50 Claims
-
1. A method for measuring a measurable capacitance, the method comprising the steps of:
-
applying a voltage to the measurable capacitance using a first switch;
allowing the measurable capacitance to share charge with a passive network;
changing a charge on the passive network by an amount of charge if the charge on the passive network is past a threshold; and
repeating each of the applying step, the allowing step, and the changing step at least once. - 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. A system for measuring a measurable capacitance, the system comprising:
-
means for repeatedly applying a voltage to the measurable capacitance using a first switch;
means for repeatedly allowing the measurable capacitance to share charge with a passive network; and
means for repeatedly changing a charge on the passive network by an amount of charge if the charge on the passive network is past a threshold.
-
-
28. An electrical circuit for measuring a measurable capacitance, the electrical circuit comprising:
-
a first switch coupled to the measurable capacitance;
a passive network coupled to the measurable capacitance, wherein the passive network is configured to store charge received from the measurable capacitance; and
a charge changing circuit coupled to the passive network; and
a controller configured to determine a value for the measurable capacitance by repeatedly applying a voltage to the measurable capacitance using the first switch, repeatedly storing charge received from the measurable capacitance on the passive network, and repeatedly changing a charge on the passive network by an amount of charge using the charge changing circuit in response to the charge on the passive network being past a threshold level. - View Dependent Claims (29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
-
Specification