ACTIVE MATRIX TOUCH SENSING
First Claim
Patent Images
1. An active matrix capacitive touch sensing pixel comprising:
- a capacitor including a first layer and a second layer;
a thin film transistor having a first terminal, a second terminal, and a gate, the first terminal being coupled with the first layer of the capacitor;
a metal pixel select bus coupled with the gate of the thin film transistor, the metal pixel select bus to supply a voltage to the gate of the thin film transistor to actively address the capacitor;
a metal drive bus coupled with the second terminal of the thin film transistor, the metal drive bus to supply an alternating current signal to the second terminal; and
a metal sense bus coupled with the second layer of the capacitor, the metal sense bus to transmit a current that varies with a capacitance of the capacitor in response to the alternating current signal received at the second terminal of the thin film transistor.
2 Assignments
0 Petitions
Accused Products
Abstract
An active matrix for a capacitive multiple touch sensing device is disclosed. One embodiment comprises one or more active matrix capacitive touch sensing pixels that each include a capacitor and a thin film transistor, wherein a voltage can be applied to the thin film transistor to address the capacitor. In this way, the thin film transistor can operate as a switch to apply an alternating current to the capacitor, and the capacitor'"'"'s capacitance can be measured in relation to the alternating current and an externally applied electric field.
50 Citations
20 Claims
-
1. An active matrix capacitive touch sensing pixel comprising:
-
a capacitor including a first layer and a second layer; a thin film transistor having a first terminal, a second terminal, and a gate, the first terminal being coupled with the first layer of the capacitor; a metal pixel select bus coupled with the gate of the thin film transistor, the metal pixel select bus to supply a voltage to the gate of the thin film transistor to actively address the capacitor; a metal drive bus coupled with the second terminal of the thin film transistor, the metal drive bus to supply an alternating current signal to the second terminal; and a metal sense bus coupled with the second layer of the capacitor, the metal sense bus to transmit a current that varies with a capacitance of the capacitor in response to the alternating current signal received at the second terminal of the thin film transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. An active matrix capacitive touch sensing device with an array of pixels, the device comprising:
-
a plurality of rows of pixels, each row being coupled with a metal drive bus; a plurality of columns of pixels, each column being coupled with a metal sense bus; a voltage source switchably coupled with a metal pixel select bus for each row of pixels, the voltage source configured to select a row of pixels by providing a voltage to that row of pixels; and a first analog multiplexer to sequentially couple the metal sense bus for each column in the array with sense circuitry; each pixel of the array of pixels comprising; a capacitor including a first layer and a second layer; a thin film transistor having a first terminal, a second terminal, and a gate, the first terminal being coupled with the first layer of the capacitor; a metal pixel select bus coupled with the gate of the thin film transistor, the metal pixel select bus to supply a voltage to the gate of the thin film transistor to actively address the capacitor; a metal drive bus coupled with the second terminal of the thin film transistor, the metal drive bus to supply an alternating current signal to the second terminal; and a metal sense bus coupled with the second layer of the capacitor, the metal sense bus to transmit a current that varies with the capacitance of the capacitor to the sense circuitry in response to the alternating current signal received at the second terminal of the thin film transistor and further in response to an electric field applied from an external input to the active matrix capacitive touch sensing device. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. A method for using an active matrix in a capacitive multiple touch sensing device, the active matrix comprising a plurality of pixels arranged in rows and columns, each pixel including a capacitor coupled with a thin film transistor, each row of pixels coupled with a metal drive bus, and each column of pixels coupled with a metal sense bus that is coupled to sense circuitry, each row of pixels further coupled with a metal pixel select bus, the method comprising:
-
applying a voltage to a metal pixel select bus to form a channel in each transistor in a row of pixels coupled with the metal pixel select bus; applying an alternating current to a capacitor through a metal drive bus and through a transistor coupled to that capacitor; sensing a capacitance of that capacitor using the sense circuitry; and detecting a change in a capacitance of the capacitor to indicate an external touch input at or near that capacitor. - View Dependent Claims (19, 20)
-
Specification