OBJECT POSITIONING FOR AN X-Y PROJECTED CAPACITIVE TOUCH PANEL

• US 20110050614A1
• Filed: 08/26/2010
• Published: 03/03/2011
• Est. Priority Date: 08/28/2009
• Status: Active Grant

• Current Assignee: Elan Microelectronics Corporation
• Original Assignee: Elan Microelectronics Corporation
• Inventors: SUNG, BRIAN, TSENG, HSUAN-WEN, TAO, YI-HSIN, TSAI, HSIN-SHIEH, NIEN, HUNG, LIN, CHIA-HSING
• Granted Patent: US 9,069,419 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• CPC Class Codes: G06F 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• 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

Methods are proposed for object positioning for an X-Y projected capacitive touch panel. In an embodiment, capacitance sensing under inphase excitation of traces is applied to set a base value when the capacitive touch panel is not touched and to obtain capacitances at intersections when the capacitive touch panel is touched, and the base value is compared with the measured capacitances to identify touch points. In other embodiments, X-Y projected sensing and all-point sensing are combined to reduce the amount of calculation and achieve the same positioning effect as an all-point capacitive touch panel.

Claims

1. A method for object positioning for an X-Y projected capacitive touch panel including three traces with a first intersection between the first and second traces and a second intersection between the first and third traces, the method comprising the steps of:

(a) in a first state, sensing the first trace under inphase excitation of the first and second traces to obtain a first measured capacitance;

(b) setting a base value according to the first measured capacitance;

(c) in a second state, sensing the first trace under inphase excitation of the first and second traces to obtain a second measured capacitance;

(d) in the second state, sensing the first trace under inphase excitation of the first and third traces to obtain a third measured capacitance; and

(e) comparing the base value with the second and third measured capacitances respectively, to identify a touched position;

wherein the X-Y projected capacitive touch panel is not touched in the first state and is touched in the second state.

2. The method of claim 1, wherein the step (b) comprises the step of increasing the base value with a number of objects on the X-Y projected capacitive touch panel increases.

3. The method of claim 1, wherein the step (e) comprises the steps of:

concluding that the first intersection is touched if the second measured capacitance is greater than the base value;

concluding that the second intersection is touched if the third measured capacitance is greater than the base value; and

concluding that the first and second intersections are touched if both the second and third measured capacitances are greater than the base value.

4. A method for object positioning for an X-Y projected capacitive touch panel including a plurality of first traces in a first direction and a plurality of second traces in a second direction, the method comprising the steps of:

(a) sequentially sensing the first traces and the second traces to generate an X-Y projected sensed frame;

(b) inphase crisscross sensing of the first traces and the second traces to generate an all-point sensed frame; and

(c) obtaining touch information of the X-Y projected capacitive touch panel according to the X-Y projected sensed frame and the all-point sensed frame.

5. A method for object positioning for an X-Y projected capacitive touch panel including a plurality of first traces in a first direction and a plurality of second traces in a second direction, the method comprising sequentially performing the steps of:

(a) sequential sensing of the first traces and the second traces to obtain X-Y projected sensing information;

(b) object number resolution for identifying an object number to be compared with one;

(c) returning to the step (a), if the object number is less than or equal to one;

(d) sequential inphase crisscross excitation of the first traces and the second traces for sensing of the first traces and the second traces to obtain all-point sensing information, if the object number is greater than one;

(e) object number resolution for identifying the object number to be compared with one;

(f) returning to the step (a) if the object number is less than or equal to one; and

(g) returning to the step (d) if the object number is greater than one.

6. A method for object positioning for an X-Y projected capacitive touch panel including a plurality of first traces in a first direction and a plurality of second traces in a second direction, the method comprising sequentially performing the steps of:

(a) sequential sensing of the first traces and the second traces to obtain X-Y projected sensing information;

(b) identification of whether or not a ghost point phenomenon is present according to the X-Y projected sensing information;

(c) returning to the step (a) if no ghost point phenomenon is present; and

(d) sequential inphase crisscross excitation of a portion of first traces and a portion of second traces near the ghost point phenomenon for sensing of the portion of first traces and the portion of second traces to obtain all-point sensing information corresponding to the portion of first traces and the portion of second traces to eliminate the ghost point phenomenon, if the ghost point phenomenon is present.