INDUCING CAPACITANCE DETECTOR AND CAPACITIVE POSITION DETECTOR OF USING SAME

• US 20110100728A1
• Filed: 11/02/2009
• Published: 05/05/2011
• Est. Priority Date: 11/02/2009
• Status: Active Grant

• Current Assignee: TCL China Star Optoelectronics Technology Co. Ltd. (TCL Technology Group Corp.)
• Original Assignee: AU Optronics Corporation
• Inventors: Chen, Chung-Chun
• Granted Patent: US 9,612,691 B2
• Time in Patent Office: Days
• US Class Current: 178/18.06
• CPC Class Codes: G06F 3/044 by capacitive means
• 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

Abstract

One aspect of the present invention relates to an inducing capacitance detector. In one embodiment, the inducing capacitance detector has an input terminal for receiving a supply voltage; a capacitive sensor array with a first output terminal and a second output terminal; an operational amplifier having an inventing input terminal electrically connected to the first output terminal of the capacitive sensor array, a non-inventing input terminal electrically connected to the second output terminal of the capacitive sensor array and the input terminal, and an output terminal for outputting an output signal, a feedback capacitor electrically connected between the inventing input terminal and the output terminal of the operational amplifier.

Claims

1. A capacitive position detector, comprising:

(a) an input for providing a supply voltage, V_IN;

(b) a capacitive sensor array, comprising;

(i) a first sensing output;

(ii) a second sensing output;

(iii) a plurality of capacitors, {C(m)}, m=1, 2, . . . , M, M being a positive integer, each capacitor C(m) having a first electrode and a second electrode;

(iv) a plurality of sensor resistors, {R_S(m)}, each sensor resistor R_S(m) having a first terminal and a second terminal, wherein the first and second terminals of the j-th sensor resistor R_S(j) are electrically connected to the first electrodes of the j-th capacitor C(j) and the (j+1)-th capacitor C(j+1), respectively, j=1, 2, . . . , (M−

1), and the first and second terminals of the M-th sensor resistor R_S(M) are electrically connected to the first electrode of the M-th capacitor C(M) and the first sensing output, respectively; and

(v) a plurality of reference resistors, {R_COM(m)}, each reference resistor R_COM(m) having a first terminal and a second terminal, wherein the first and second terminals of the j-th reference resistor R_COM(j) are electrically connected to the second electrodes of the j-th capacitor C(j) and the (j+1)-th capacitor C(j+1), respectively, and the first and second terminals of the M-th reference resistor R_COM(M) are electrically connected to the second electrode of the M-th capacitor C(M) and the second sensing output, respectively; and

(c) an operational amplifier having an inverting input terminal electrically coupled to the first sensing output of the capacitive sensor array, and a non-inverting input terminal, and an output terminal, wherein the non-inverting input terminal and the second sensing output of the capacitive sensor array are electrically connected in common to the input, and wherein an output terminal is adapted for outputting an output signal, V_OUT; and

(d) a feedback capacitor C_T is electrically connected between the inventing input terminal and the output terminal of the operational amplifier.

2. The inducing capacitance detector of claim 1, wherein each of the plurality of capacitors, {C(m)} has a capacitance, C_S.

3. The inducing capacitance detector of claim 1, wherein each of the plurality of the sensor resistors {R_S(m)} has a resistance R_S, wherein each of the plurality of reference resistors {R_COM(m)} has a resistance R_COM, and wherein R_S and R_COM are identical or different.

4. The inducing capacitance detector of claim 1, further comprising a switch S_R is electrically connected between the inventing input terminal and the output terminal of the operational amplifier.

5. The inducing capacitance detector of claim 1, further comprising two resistors R_P1 and R_P2, wherein the resistor R_P1 is electrically connected between the first detecting input and the inverting input terminal of the operational amplifier, and the resistor R_P2 is electrically connected between the second detecting input and the non-inverting input terminal of the operational amplifier, respectively.

6. The inducing capacitance detector of claim 1, wherein the output signal at a given time t, V_OUT(t), satisfies the following formula:

7. A capacitive position detector, comprising:

(d) an input for providing a supply voltage, V_IN;

(e) a capacitive sensor array, comprising;

(vi) a first sensing output;

(vii) a second sensing output;

(viii) a plurality of capacitors, {C(m)}, m=1, 2, . . . , M, M being a positive integer, each capacitor C(m) having a first electrode and a second electrode;

(ix) a plurality of sensor resistors, {R_S(m)}, each sensor resistor R_S(m) having a first terminal and a second terminal, wherein the first and second terminals of the j-th sensor resistor R_S(j) are electrically connected to the first electrodes of the j-th capacitor C(j) and the (j+1)-th capacitor C(j+1), respectively, j=1, 2, . . . , (M−

1), and the first and second terminals of the M-th sensor resistor R_S(M) are electrically connected to the first electrode of the M-th capacitor C(M) and the first sensing output, respectively; and

(x) a plurality of reference resistors, {R_COM(m)}, each reference resistor R_COM(m) having a first terminal and a second terminal, wherein the first and second terminals of the j-th reference resistor R_COM(j) are electrically connected to the second electrodes of the j-th capacitor C(j) and the (j+1)-th capacitor C(j+1), respectively, and the first and second terminals of the M-th reference resistor R_COM(M) are electrically connected to the second electrode of the M-th capacitor C(M) and the second sensing output, respectively; and

(c) a detecting unit having a first detecting input and a second detecting input, wherein the first detecting input is electrically connected to the first sensing output of the capacitive sensor array, and the second detecting input and the second sensing output of the capacitive sensor array are electrically connected in common to the input.

8. The inducing capacitance detector of claim 7, wherein the detecting unit comprises:

(a) an operational amplifier having an inverting input terminal electrically coupled to the first detecting input, a non-inverting input terminal electrically coupled to the second detecting input, a first output terminal for outputting a first output signal, V_OUTP, and a second output terminal for outputting a second output signal, V_OUTN;

(b) a first feedback capacitor C_T1 is electrically connected between the first detecting input and the first output terminal of the operational amplifier;

(c) a second feedback capacitor C_T2 is electrically connected between the second detecting input and the second output terminal of the operational amplifier;

(d) a first switch S_R1 is electrically connected between electrically connected between the first detecting input and the first output terminal of the operational amplifier; and

(e) a second switch S_R2 is electrically connected between electrically connected between the second detecting input and the second output terminal of the operational amplifier.

9. The inducing capacitance detector of claim 8, wherein each of the first feedback capacitor C_T1 and the second feedback capacitor C_T2 has a capacitance C_T.

10. The inducing capacitance detector of claim 9, wherein the first output signal V_OUTT and the second output signal V_OUTN are opposite to each other.

11. The inducing capacitance detector of claim 10, wherein the first output signal V_OUTP at a given time t, V_OUTP(t), and the second output signal V_OUTN at a given time t, V_OUTN(t), respectively satisfy the following formulas:

12. The inducing capacitance detector of claim 8, wherein the detecting unit further comprises:

(a) an additional operational amplifier having an inverting input terminal, a non-inverting input terminal, and an output terminal for outputting an output signal, V_OUTT;

(b) a pair of first resistors R₁, one of the pair of first resistors R₁ electrically connected between the first output terminal of the operational amplifier and the non-inverting input terminal of the additional operational amplifier, and the other of the pair of first resistor R₁ electrically connected between the second output terminal of the operational amplifier and the inverting input terminal of the additional operational amplifier; and

(c) a pair of second resistors R₂, one of the pair of second resistors R₂ electrically connected between the non-inverting input terminal of the additional operational amplifier and a reference voltage supply, and the other of the pair of second resistor R₂ electrically connected between the inverting input terminal and the output terminal of the additional operational amplifier.

13. The inducing capacitance detector of claim 12, wherein the output signal V_OUTT at a given time t, V_OUTT(t), satisfies the following formula:

14. A capacitive position detection device comprising a plurality of inducing capacitance detectors of claim 7.

15. A capacitive position detection device, comprising:

(b) a plurality of sensor loading models, {S(m, n)}, m=1, 2, . . . , M, n=1, 2, . . . , N, each of M and N being an positive integer, spatially arranged in the form of matrix having M rows and N columns, each sensor loading model S(m, n) comprises;

(i) first, second, third and fourth X-axis terminals, X₁(m), X₂(m), X₃(m) and X₄(m);

(ii) first, second, third and fourth four Y-axis terminals, Y₁(n), Y₂(n), Y₃(n) and Y₄(n);

(iii) an X-axis sensor resistor, R_X, electrically connected between the first and third X-axis terminals X₁(m) and X₃(m);

(iv) an X-axis VCOM resistor, R_XCOM, electrically connected between the second and fourth X-axis terminals X₂(m) and X₄(m);

(v) a Y-axis sensor resistor, R_Y, electrically connected between the first and third Y-axis terminals Y₁(n) and Y₃(n);

(vi) a Y-axis VCOM resistor, R_YCOM, electrically connected between the second and fourth Y-axis terminals Y₂(n) and Y₄(n);

(vii) an X-axis capacitor, C_X, electrically connected between the first and second X-axis terminals X₁(m) and X₂(m);

(viii) a Y-axis capacitor, C_Y, electrically connected between the third and fourth Y-axis terminals Y₃(n) and Y₄(n); and

(ix) a X-Y-axis cross capacitor, C_XY, electrically connected between the first Y-axis terminal Y₁(n) and the second X-axis terminal X₂(m);

wherein for the n-th column, the first and second X-axis terminals X₁(j+1) and X₂(j+1) of the (j+1)-th row sensor loading model S(j+1, n) are electrically connected to the third and fourth X-axis terminals X₃(j) and X₄(j) of the j-th row sensor loading model S(j, n), j=1, 2, . . . , (M−

1); and

wherein for the m-th row, the first and second Y-axis terminals Y₁(k+1) and Y₂(k+1) of the (k+1)-th column sensor loading model S(m, k+1) are electrically connected to the third and fourth Y-axis terminals Y₃(k) and Y₄(k) of the k-th column sensor loading model S(m, k), k=1, 2, . . . , (N−

1); and

(c) M X-axis detecting units, {D_X(m)}, m=1, 2, . . . , M, each X-axis detecting unit D_X(m) having first and second detecting inputs electrically connected to the third and fourth Y-axis terminals Y₃(N) and Y₄(N) of the m-th row and N-th column sensor loading model S(m, N), respectively;

(d) N Y-axis detecting units, {D_Y(n)}, n=1, 2, . . . , N, each Y-axis detecting unit D_Y(n) having first and second detecting inputs electrically connected to the third and fourth X-axis terminals X₃(M) and X₄(M) of the M-th row and n-th column sensor loading model S(M, n), respectively.

16. The capacitive position detection device of claim 15, wherein each X-axis detecting unit D_X(m) and each Y-axis detecting unit D_Y(n) are identical to each other.

17. The capacitive position detection device of claim 16, wherein each X-axis detecting unit D_X(m) comprises:

(a) an operational amplifier having an inverting input terminal electrically coupled to the first detecting input, a non-inverting input terminal electrically coupled to the second detecting input and an output terminal for outputting an output signal; and

(b) a feedback capacitor C_T is electrically connected between the first detecting input and the output terminal of the operational amplifier.

18. The capacitive position detection device of claim 17, wherein the operational amplifier has a third input terminal electrically connected to a supply voltage

19. The capacitive position detection device of claim 17, wherein each X-axis detecting unit D_X(m) further comprises two resistors R_P1 and R_P2, wherein the resistor R_P1 is electrically connected between the first detecting input and the inverting input terminal of the operational amplifier, and the resistor R_P2 is electrically connected between the second detecting input and the non-inverting input terminal of the operational amplifier, respectively.

20. The capacitive position detection device of claim 16, wherein each X-axis detecting unit D_X(m) comprises:

(a) an operational amplifier having an inverting input terminal electrically coupled to the first detecting input, a non-inverting input terminal electrically coupled to the second detecting input, a third input terminal electrically connected to a supply voltage, a first output terminal for outputting a first output signal, and a second output terminal for outputting a second output signal;

(b) a first feedback capacitor C_T1 is electrically connected between the first detecting input and the first output terminal of the operational amplifier; and

(c) a second feedback capacitor C_T2 is electrically connected between the second detecting input and the second output terminal of the operational amplifier.

21. The capacitive position detection device of claim 20, wherein each of the first feedback capacitor C_T1 and the second feedback capacitor C_T2 has a capacitance C_T.

22. The capacitive position detection device of claim 20, wherein each X-axis detecting unit D_X(m) further comprises two resistors R_P1 and R_P2, wherein the resistor R_P1 is electrically connected between the first detecting input and the inverting input terminal of the operational amplifier, and the resistor R_P2 is electrically connected between the second detecting input and the non-inverting input terminal of the operational amplifier, respectively.

23. The capacitive position detection device of claim 23, wherein the detecting unit further comprises:

(a) an additional operational amplifier having an inverting input terminal, a non-inverting input terminal, a third input terminal electrically connected to a supply voltage, and an output terminal for outputting an output signal;

(b) a pair of first resistors R₁, one of the pair of first resistors R₁ electrically connected between the first output terminal of the operational amplifier and the non-inverting input terminal of the additional operational amplifier, and the other of the pair of first resistor R₁ electrically connected between the second output terminal of the operational amplifier and the inverting input terminal of the additional operational amplifier; and

(c) a pair of second resistors R₂, one of the pair of second resistors R₂ electrically connected between the non-inverting input terminal of the additional operational amplifier and a voltage supply, and the other of the pair of second resistor R₂ electrically connected between the inverting input terminal and the output terminal of the additional operational amplifier.

24. The capacitive position detection device of claim 23, wherein the detecting unit further comprises a pair of capacitors C_R, one of the pair of capacitors C_R electrically connected between the first output terminal of the operational amplifier and the ground, and the other of the pair of capacitors C_R electrically connected between the second output terminal of the operational amplifier and the ground.