LOW POWER DRIVING AND SENSING METHOD AND SYSTEM FOR CAPACITIVE TOUCH PANELS

• US 20130155007A1
• Filed: 09/12/2012
• Published: 06/20/2013
• Est. Priority Date: 12/20/2011
• Status: Active Grant

• Current Assignee: Orise Technology Co., Ltd (FocalTech Systems Co.,Ltd)
• Original Assignee: Chien Ying Huang
• Inventors: HUANG, Yen Lin, HUANG, Chien Ying
• Granted Patent: US 8,970,527 B2
• Time in Patent Office: Days
• US Class Current: 345/174
• CPC Class Codes: G06F 3/041662 using alternate mutual and self-capacitive scanning
• 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

A low power driving and sensing system for capacitive touch panels includes a capacitive touch panel, a first switch device, a second switch device, a driving device, a sensing device, and a control device. The capacitive touch panel has plural first conductor lines arranged in a first direction and plural second conductor lines arranged in a second direction. The driving device is connected to the first switch device for driving the capacitive touch panel. The sensing device is connected to the second switch device for sensing the capacitive touch panel. The control device configures the first switch device and the second switch device for entering the capacitive touch panel into a self-capacitance mode such that the driving device and the sensing device perform a self capacitance sensing, and into a mutual capacitance mode such that the driving device and the sensing device perform a mutual capacitance sensing.

Claims

1. A low power driving and sensing system for capacitive touch panels, comprising:

a capacitive touch panel, having a plurality of first conductor lines arranged in a first direction and a plurality of second conductor lines arranged in a second direction, wherein the first conductor lines and the second conductor lines include parasitic and stray capacitance respectively, and a mutual capacitance is formed at each overlap of the first and second conductor lines;

a first switch device, connected to the capacitive touch panel;

a second switch device, connected to the capacitive touch panel;

a driving device, connected to the first switch device, for driving the capacitive touch panel through the first switch device;

a sensing device, connected to the second switch device, for sensing a signal outputted by the capacitive touch panel through the second switch device; and

a control device, connected to the first switch device, the second switch device, the driving device, and the sensing device, for configuring the first switch device and the second switch device to allow the capacitive touch panel to enter into a self capacitance mode, such that the driving device and the sensing device perform a self capacitance sensing, and to enter into a mutual capacitance mode, such that the driving device and the sensing device perform a mutual capacitance sensing,

wherein when the sensing device performs the self capacitance sensing, the control device determines that a number of touch points on the capacitive touch panel is smaller than a second predetermined number and accordingly maintains configuration of the first switch device and second switch device, such that the sensing device performs the self capacitance sensing, and otherwise the control device configures the first switch device and the second switch device, such that the sensing device performs the mutual capacitance sensing.

2. The system as claimed in claim 1, wherein, when the sensing device performs the mutual capacitance sensing, the control device determines that the number of touch points on the capacitive touch panel is smaller than a first predetermined number and accordingly configures the first switch device and the second switch device, such that the sensing device performs the self capacitance sensing.

3. The system as claimed in claim 2, wherein, when the sensing device performs the mutual capacitance sensing, the control device determines that the number of touch points on the capacitive touch panel is greater than or equal to the first predetermined number and accordingly maintains configuration of the first switch device and the second switch device, such that the sensing device performs the mutual capacitance sensing.

4. The system as claimed in claim 1, wherein the capacitive touch panel includes k first conductor lines arranged in the first direction and k second conductor lines arranged in the second direction;

the first switch device includes k 1-to-2 switches, the driving device includes k drivers, and an i-th 1-to-2 switch has a first terminal connected to an i-th driver, a second terminal connected to an i-th second conductor line, and a third terminal connected to an i-th first conductor line, where 1≦

i≦

k.

5. The system as claimed in claim 4, wherein the second switch device includes k 2-to-1 switches;

the sensing device includes k sensors, and an i-th 2-to-1 switch has a first terminal connected to an i-th sensor, a second terminal connected to the i-th first conductor line, and a third terminal connected to the i-th second conductor line.

6. The system as claimed in claim 5, wherein the self capacitance sensing includes a first direction self capacitance sensing and a second direction self capacitance sensing.

7. The system as claimed in claim 5, wherein when the first direction self capacitance sensing is performed, the control device configures the i-th 1-to-2 switch and the i-th 2-to-1 switch, such that the i-th driver and the i-th sensor are connected to the i-th first conductor line, and when the second direction self capacitance sensing is performed, the control device configures the i-th 1-to-2 switch and the i-th 2-to-1 switch, such that the i-th driver and the i-th sensor are connected to the i-th second conductor line.

8. The system as claimed in claim 7, wherein when the first direction mutual capacitance sensing is performed, the control device configures the i-th 1-to-2 switch and the i-th 2-to-1 switch, such that the i-th driver is connected to the i-th first conductor line, and the i-th sensor is connected to the i-th second conductor line.

9. The system as claimed in claim 3, wherein the capacitive touch panel includes m first conductor lines arranged in the first direction and n second conductor lines arranged in the second direction, the first switch device includes m (m+n)-to-1 switches, the driving device includes m drivers, the sensing device includes n sensors, and a j-th (m+n)-to-1 switch has a first terminal connected to a j-th first conductor line, and a second terminal to (m+n+1)-th terminals connected to the m drivers and n sensors, respectively, where m, n are each a positive integer, m is not equal to n, and 1≦

j≦

m.

10. The system as claimed in claim 9, wherein the second switch device includes n 1-to-(m+n) switches, a g-th 1-to-(m+n) switch has a first terminal connected to a g-th second conductor line, and second to (m+n+1)-th terminals connected to the m drivers and n sensors, respectively, where 1≦

g≦

n.

11. The system as claimed in claim 10, wherein the self capacitance sensing includes a first direction self capacitance sensing and a second direction self capacitance sensing, and the control device configures the j-th (m+n)-to-1 switch when the first direction self capacitance sensing is performed, such that the first driver and the first sensor are connected to the j-th first conductor line.

12. The system as claimed in claim 11, wherein when the second direction self capacitance sensing is performed, the control device configures the g-th 1-to-(m+n) switch, such that the first driver and the first sensor are connected to the g-th second conductor line.

13. The system as claimed in claim 12, wherein when the mutual capacitance sensing is performed, the control device configures the j-th (m+n)-to-1 switch and the g-th 1-to-(m+n) switch, such that a j-th driver is connected to the j-th first conductor line, and a g-th sensor is connected to the g-th second conductor line.

14. The system as claimed in claim 3, wherein the capacitive touch panel includes m first conductor lines arranged in the first direction and n second conductor lines arranged in the second direction, the first switch device includes m (m+n+z)-to-1 switches, the driving device includes m mutual capacitance drivers and z self capacitance driving and sensing units, the sensing device includes n mutual capacitance sensors, a j-th (m+n+z)-to-1 switch has a first terminal connected to a j-th first conductor line, and second to (m+n+z+1)-th terminals connected to the m drivers, z self capacitance driving and sensing units, and n sensors, respectively, where m, n are each a positive integer, m is not equal to n, and 1≦

j≦

m.

15. The system as claimed in claim 14, wherein the second switch device includes n 1-to-(m+n+z) switches;

a g-th 1-to-(m+n+z) switch has a first terminal connected to a g-th second conductor line, and a second terminal to (m+n+z+1)-th terminals connected to the m drivers, z self capacitance driving and sensing units, and n sensors, respectively, where 1≦

g≦

n.

16. A low power driving and sensing method for a capacitive touch system including a capacitive touch panel, a first switch device, a second switch device, a driving device, a sensing device, and a control device, wherein the capacitive touch panel having a sleep mode, a self capacitance mode, and a mutual capacitance mode, the low power driving and sensing method comprising the steps of:

(A) using the control device to determine whether a self capacitance of the capacitive touch panel is changed when the capacitive touch panel enters into the self capacitance mode from the sleep mode, and executing step (B) when the self capacitance of the capacitive touch panel is changed, otherwise returning to step (A);

(B) using the control device to determine whether a number of touch points on the capacitive touch panel is greater than or equal to a second predetermined number, and executing step (C) when the number of touch points on the capacitive touch panel is greater than or equal to the second predetermined number;

(C) using the control device to configure the first switch device and the second switch device for allowing the capacitive touch panel to enter into the mutual capacitance mode such that the sensing device performs a mutual capacitance sensing, using the control device to determine whether a mutual capacitance of the capacitive touch panel is changed, and executing step (D) when the mutual capacitance of the capacitive touch panel is changed, otherwise returning to step (A); and

(D) using the control device to determine whether the number of touch points on the capacitive touch panel is greater than or equal to a first predetermined number, and executing step (C) when the number of touch points on the capacitive touch panel is greater than or equal to the first predetermined number, otherwise returning to step (A).

17. The method as claimed in claim 16, wherein step (A) is executed when the control device in step (B) determines that the number of touch points on the capacitive touch panel is not greater than or equal to the second predetermined number.

18. The method as claimed in claim 17, wherein step (A) is executed when the control device in step (D) determines that the number of touch points on the capacitive touch panel is not greater than or equal to the first predetermined number.

19. The method as claimed in claim 16, wherein the control device in step (A) compares a pre-stored self capacitance data for the capacitive touch panel with a self capacitance data sensed by the sensing device so as to determine whether the self capacitance of the capacitive touch panel is changed.

20. The method as claimed in claim 19, wherein the control device in step (C) compares a pre-stored mutual capacitance data for the capacitive touch panel with a mutual capacitance data sensed by the sensing device so as to determine whether the mutual capacitance of the capacitive touch panel is changed.