US 2011/0210924 A1Published application

Snr enhancement for differential input device

AssigneeAu Optronics Corporation

InventorsChun-Wei Yang, Chia-Feng Yang, Yu-Min Hsu, Yung-Tse Cheng

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Abstract

The present invention relates to a position detector and a touch sensing device of using same with SNR enhancement. In one embodiment, the position detector has (P+1) inputs, each input for receiving an input signal associated with a position, P being a positive integer, and P operational amplifiers, each operational amplifier having a non-inverting input and an inverting input, where the inverting input of the j-th operational amplifier is electrically connected to the non-inverting input of the (j+1)-th operational amplifier, and the non-inverting input and the inverting input of the j-th operational amplifier are electrically connected to the j-th input port and the (j+1)-th input port, respectively, j=1, 2, 3, . . . , (P−1).

Claims16

Dependent claims

A touch sensing device, comprising:

(a) a sensor matrix comprising (M+1) x-axis sensors spatially arranged in an x-axis direction, and (N+1) y-axis sensors spatially arranged crossing over the (M+1) x-axis sensors in a y-axis direction substantially perpendicular to the x-axis direction, M, N being a positive integer;
(b) an x-axis detector comprising:
(i) M operational amplifiers, the m-th operational amplifier having a non-inverting input electrically connected to the m-th x-axis sensor, an inverting input electrically connected to the (m+1)-th x-axis sensor, and an output, m=1, 2, 3, . . . , M;
(ii) M gain amplifiers, the m-th gain amplifier having an input electrically connected to the output of the m-th operational amplifier, and an output;
(iii) M reference capacitors, the m-th reference capacitor having a first terminal electrically connected to the output of the m-th gain amplifier, and a second terminal electrically connected to ground;
(iv) M switches, the m-th switch having a first terminal electrically connected to the output of the m-th gain amplifier, and a second terminal;
(v) an analog-to-digital converter (ADC) having an input electrically connected to the second terminal of each of the M switches, and an output, and
(vi) a subtraction circuit having an input electrically connected to the output of the ADC and an output for outputting touch sensing signals of the (M+1) x-axis sensors;
and
(c) a y-axis detector comprising:
(i) N operational amplifiers, the n-th operational amplifier having a non-inverting input electrically connected to the n-th y-axis sensor, an inverting input electrically connected to the (n+1)-th y-axis sensor, and an output, n=1, 2, 3, . . . , N;
(ii) N gain amplifiers, the n-th gain amplifier having an input electrically connected to the output of the n-th operational amplifier, and an output;
(iii) N reference capacitors, the n-th reference capacitor having a first terminal electrically connected to the output of the n-th gain amplifier, and a second terminal electrically connected to ground;
(iv) N switches, the n-th switch having a first terminal electrically connected to the output of the n-th gain amplifier, and a second terminal;
(v) an analog-to-digital converter (ADC) having an input electrically connected to the second terminal of each of the N switches, and an output, and
(vi) a subtraction circuit having an input electrically connected to the output of the ADC and an output for outputting touch sensing signals of the (N+1) y-axis sensors.

13 more elements

A position detector usable for a touch sensing device, comprising:

(a) (P+1) input ports, each input for receiving an input signal associated with a position, P being a positive integer;
(b) P operational amplifiers, the j-th operational amplifier having a non-inverting input electrically connected to the j-th input port, an inverting input electrically connected to the (j+1)-th input port, and an output, j=1, 2, 3, . . . , P;
(c) P gain amplifiers, the j-th gain amplifier having an input electrically connected to the output of the j-th operational amplifier, and an output;
(d) P reference capacitors, the j-th reference capacitor having a first terminal electrically connected to the output of the j-th gain amplifier, and a second terminal electrically connected to ground;
(e) P switches, the j-th switch having a first terminal electrically connected to the output of the j-th gain amplifier, and a second terminal;
(f) an analog-to-digital converter (ADC) having an input electrically connected to the second terminal of each of the P switches, and an output, and
(g) a subtraction circuit having an input electrically connected to the output of the ADC and an output for outputting an output signal identified the position.

4 more elements

Dependencies are inferred from the claim text.