Touch device for determining real coordinates of multiple touch points and method thereof

A touch device for determining real coordinates of multiple touch points is provided. The touch device for determining real coordinates of the multiple touch points comprises a plurality of electrodes and a scanning circuit having a Normal Scanning Circuit and a Split Scanning Circuit connected to said electrodes for eliminating ghost coordinates of the multiple touch points from raw coordinates to output the real coordinates of the multiple touch points. The method of determining real coordinates of multiple touch points on the touch device is also provided.

BACKGROUND OF THE INVENTION

This application claims the benefit of People's Republic of China Application No. 201010550974.9, filed on Nov. 13, 2010.

FIELD OF THE INVENTION

The present invention relates to a touch device for determining real coordinates of multiple touch points and a method thereof.

DESCRIPTION OF THE RELATED ART

In the last two decades, touch technologies have been applied in a variety of consumer applications such as touch screens in automated-teller machines (ATMs), track pads in laptop computers, and scroll wheels in media players. In these consumer applications, movement of an object such as a finger or a stylus along a surface of a touch device is detected by a touch sensor inside of the touch device, wherein the touch sensor generates electrical signals for subsequent processing.

There are many types of touch sensing methods such as resistive sensing, capacitive sensing, acoustic wave sensing, and optical sensing. In the capacitive sensing method, a touch sensor perceives touch locations by detecting change in capacitance due to proximity of a conductive object such as a metal or a part of human body. Capacitive touch sensors are classified as projective capacitive type and surface capacitive type. A projective capacitive type touch sensor contains a lattice electrode pattern whereas a surface capacitive touch sensor includes electrodes formed on peripheral edges of a continuous conductive sheet.

FIG. 1aandFIG. 1bshow a conventional projective capacitive touch device1comprising a plurality of first electrodes2in a first direction, a plurality of second electrodes3in a second direction, an insulator4, a substrate5, wires6, and a processor7. The plurality of first electrodes2and the plurality of second electrodes3intersect each other to form a lattice pattern placed on the substrate5. Insulator4is arranged between the plurality of first electrodes2and the plurality of second electrodes3. Processor7is connected to the plurality of first electrodes2and the plurality of second electrodes3by wires6. When a conductive object such as a finger or a stylus touches or moves on the surface of the projective capacitive touch device1, change in self capacitance produced on both first electrodes2in the first direction and second electrodes3in the second direction can be transmitted and then processed by the processor7. Centroids of the change in self capacitance indicate locations of the touch point in the first direction and in the second direction. Coordinate of the touch point is calculated by intersecting the centroids in the first direction and the second direction. In other words, the conventional method of detecting touch point comprises: (a) scanning both the first. electrodes2in the first direction and the second electrodes3in the second direction; (b) computing centroids of the change in self capacitance in the first direction and the second direction; and (c) calculating the coordinate of the touch point based on the centroids.

FIG. 2shows that when two touch points G and H appear on surface of the projective capacitive touch device1, two centroids8a,8bare computed on the first electrodes2and two centroids9a,9bare computed on the second electrodes3. Thus, four raw coordinates G (8a,9a), G′ (8a,9b), H′ (8b,9a), H (8b,9b) are formed. However, in these four raw coordinates, only two are real coordinates indicating the two touch points G, H, and the other two are defined as “ghost coordinates”, which are coordinates of so-called “ghost points”.

As a result, conventional projective capacitive touch devices have appearance of ghost coordinates, which limit the application and operation of the touch device for determining multiple touch points. Therefore, it is necessary to eliminate ghost coordinates during the process of determining multiple touch points located on a touch device as mentioned above.

SUMMARY OF THE INVENTION

It. is an object of the present invention to provide a touch device for determining multiple touch points, wherein the touch device eliminates ghost coordinates from raw coordinates of the multiple touch points to determine real coordinates.

The present disclosure relates to a touch device for determining real coordinates of multiple touch points comprises a plurality of electrodes and a scanning circuit, wherein the scanning circuit further comprises of a Normal Scanning Circuit and a Split Scanning Circuit connected to the plurality of electrodes. Normal Scanning Circuit is a circuit for scanning the electrodes for detecting taw coordinates of multiple touch points (herein referred to as “Normal Scanning Circuit”). Split Scanning Circuit is a circuit for scanning electrode parts, wherein the electrodes are divided into two separate parts. The first part comprises of first A electrodes and first B electrodes, and the second part comprises of second A electrodes and second B electrodes. The split scanning circuit, after scanning, eliminates ghost coordinates of the multiple touch points from the raw coordinates of multiple touch points to determine real coordinates of the multiple touch points (herein referred to as the “Split Scanning Circuit”).

It is another object of the present invention to provide a method of determining real coordinates of multiple touch points.

The present disclosure further relates to a method of determining real coordinates of multiple touch points, wherein the method comprises: (a) scanning a plurality of electrodes both in a first direction and a second direction to detect raw coordinates of said multiple touch points by a Normal Scanning Circuit; and (b) scanning said electrodes to determine real coordinates of said touch points in said raw coordinates by a Split Scanning Circuit.

By means of the present invention, a touch device can eliminate ghost coordinates and output only real coordinates during the process of determining multiple touch points thus overcoming the disadvantage of those conventional touch devices.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIGS. 3aand3bshow a touch device100for determining real coordinates of multiple touch points in accordance with a first embodiment of the present invention. The touch device100comprises a substrate110, a plurality of first electrodes120disposed in the first direction X, a plurality of second electrodes130disposed in the second direction Y, an insulating layer140, a processor150, wires170and switches161,162,163,164. The first electrodes120are placed on the substrate110. The first direction is different from the second direction. The first electrodes120and the second electrodes130disposed on the two opposite sides of the insulating layer140are intersected with each other to form a plurality of intersection points. In an embodiment, the insulating layer140is of the shape of a plate and provides insulation between the first electrodes120and the second electrodes130. Moreover, each of the first electrodes120comprises a plurality of divided electrodes and each of the second electrodes comprises a plurality of divided electrodes. Preferably, each first electrode120is divided into two separate electrode parts in the first direction X, right and left, a first A electrode121and a first B electrode122, while each second electrode130is divided into two separate electrode parts in the second direction Y, upper and lower, a second A electrode131and a second B electrode132. Therefore, the first A electrode121intersect with the second A electrode131to form a first electrode area Q1. In the same way, the first B electrode122intersect with the second. A electrode131to form a first electrode area Q2; the first A electrode121intersect with the second B electrode132to form a first electrode area Q3; the first B electrode122intersect with the second B electrodes132to form a first electrode area Q4. The first A electrodes121are connected to the processor150with switches161. In the same way, the first B electrodes122are connected to the processor150with switches162; the second A. electrodes131are connected to the processor150with switches163; the second B electrodes132are connected to the processor150with switches164. The touch device100further comprises a scanning circuit (not shown) having a Normal Scanning Circuit and a Split. Scanning Circuit. These two different scanning circuits are both utilized to scan the first electrodes120and the second electrodes130, when multiple touch points occur on the touch device100.

In an embodiment, switches161,162,163,164are controlled by a scanning circuit. When all switches161,162,163,164are closed to transmit scanning signals to electrodes, scanning signals are transmitted to both first A electrodes121and first B electrodes122resulting in electrodes121and122together performing as a whole structure i.e the first electrodes120perform. Similarly, scanning signals are transmitted to both the second A electrodes1131and the second B electrodes132, resulting in electrodes131and132together performing as the whole structure i.e the second electrodes130perform. At this time, the Normal Scanning Circuit starts to scan the first electrodes120and the second electrodes130.

In an embodiment, when switches161connected to first A electrodes121are closed and other switches162,163,164are open, Split Scanning Circuit starts to scan the first A electrodes121. Similarly, when switches162connected to first B electrodes122are closed and other switches161,163,164are open, Split Scanning Circuit starts to scan the first B electrodes122. When switches163connected to second A electrodes131are closed and other switches161,162,164are open, Split Scanning Circuit starts to scan the second A electrodes131. When switches164connected to second B electrodes132are closed and other switches161,162,163are open, Split Scanning Circuit starts to scan the second B electrodes132.

To fulfill various design requirements, configuration of the first. A electrodes121, the first B electrodes122, the second A electrodes131, and the second B electrodes132have different forms. For instance, the first A electrodes121are symmetrical to the first B electrodes122, while the second A electrodes131are symmetrical to the second B electrodes132, making the four electrode areas Q1, Q2, Q3, Q4symmetrical to each other. In another instance, the first A electrodes121are not symmetrical to the. first B electrodes122and the second A electrodes131are not symmetrical to the second B electrodes132, making the four electrode areas Q1, Q2, Q3, Q4non-symmetrical to each other.

FIGS. 4aand4billustrate a touch device200for determining real coordinates of multiple touch points in accordance with a second embodiment of the present invention. Similar to touch device100and in the accordance with the first embodiment of the present invention, the touch device200comprises a substrate210, a plurality of first electrodes220disposed in the first direction X, a plurality of second electrodes230disposed in the second direction Y, a plurality of insulating elements240, a processor250, wires270and switches261,262,263,264. The difference is that the first electrodes220and the second electrodes230are both placed on the substrate210. To insulate the first electrodes220from the second electrodes230, the insulating elements240are located between the first electrodes220and the second electrodes230at the intersection points of the two electrodes. In addition, each first electrode220is divided into two separate electrode parts, a first A electrode221and a first B electrode222, in the first direction X, while each second electrode230is divided into two separate electrode parts, a second A electrode231and a second B electrode232, in the second direction Y. The other components of the touch device200according to the second embodiment of the present invention are the same as those of the touch device100mentioned above.

The shape of the first electrodes and the second electrodes could be of any geometry contour or combination of different geometry contours such as stripe, polygon and so on.

In an embodiment, of the first electrodes and the second electrodes, there are at least two electrodes in each of the two directions in the present invention. Resolution and size of the proposed touch device are main factors influencing the number of electrodes. Usually, a higher resolution or larger size requires more electrodes.

Being applied in various devices, touch device of the present invention may be opaque such as in touch pads of a laptop computer or may be transparent such as in touch screen of a cell phone. In an embodiment, first and second electrodes are made of conductive material while the insulating layer and the insulating elements are made of insulating material. Opaque conductive material can be selected from copper, alumina, gold and other metals, while the transparent conductive material could be Indium Tin Oxides (ITO), Aluminum-doped zinc Oxide, transparent conductive oxides and so on. The insulating material could be plastic, glass and so on.

When at least two touch points appear on surface of a touch device for determining real coordinates of multiple touch points, the real coordinates of the touch points can be determined by using the method of determining real coordinates of multiple touch points shown inFIG. 5. A situation of two touch points appearing on a surface of a projective capacitive touch device is taken as an example, referring toFIGS. 6a-6c. The process starts at step10where the touch device is in standby. When two touch points, A and B, occur in two neighboring electrode areas on the surface of the touch device, the process proceeds to step11.

In step11, all switches are closed and then the processor respectively applies a scanning signal to the first electrodes and the second electrodes through wires. Normal Scanning Circuit scans the first electrodes in the first direction X and the second electrodes in the second direction Y. The signals representing the changes in the self-capacitance in both the first direction X and the second direction Y caused by two touch points A and B are transmitted to the processor (not shown).

Step12is implemented, in which centroids x1, x2, representing changes in self capacitance, corresponding to two touch points A, B in the first direction .X and the centroids y1, y2, representing changes in self capacitance, corresponding to two touch points A, B in the second direction Y are computed by the processor based on the signals representing the changes in the self-capacitance created in step11. According to location and definition of the second A electrodes131and the second B electrodes132, the processor can determine that the centroid y1is on the second A electrodes131and the centroid y2is on the second B electrodes132. By intersecting the centroids x1, x2, y1, y2, four raw coordinates a(x1,y1), b(x2,y2), a′(x1,y2) and b′(x2,y1) are calculated, referring toFIG. 6a.

In step13, it is determined whether only one centroid is computed in either the first direction X or the second direction Y in step13. If two centroids are computed in both the first direction X and the second direction Y, which presents that x1is not equal to x2and y1is not equal to y2, the process proceeds to step14, in which the processor defines two diagonal coordinates of those four raw coordinates as belonging to one group, leading to two groups of raw coordinates, i.e. a(x1,y1), b(x2,y2) in one group and a′ (x1,y2), b′(x2,y1) in another group. As ghost coordinates exist, raw coordinates in one of the two groups are real coordinates, while the raw coordinates in the other group are ghost coordinates.

In step15, only the switches connected to the first A electrodes121are closed while other switches are open and then the processor transmits the scanning signal to the first A electrodes121through wires. Split Scanning Circuit scans the first A electrodes121. Signals representing changes in self capacitance caused by touch points are transmitted to the processor, as illustrated inFIG. 6b. The processor computes the centroids of changes in self capacitance based on the signals transmitted to the processor.

In step16, it is determined whether there is the only one centroid computed in step15. If there are two centroids in step15, the process proceeds to step17.

In step17, only the switches connected to the second A electrodes131are closed while other switches are open and then the processor transmits the scanning signal to the second A electrodes131through wires. Split Scanning Circuit scans the second A electrodes131. Signals representing changes in self capacitance caused by touch points are transmitted to the processor, as illustrated inFIG. 6c. The processor computes the centroids of changes in self capacitance based on the signals transmitted to the processor.

After step17, only one centroid xl is computed. Moreover, only centroid y1computed in step12is on the second A electrodes131. Thus, the raw coordinates a(x1, y1) are the real coordinates and are in the same group as their diagonal coordinates b(x2, y2). Therefore the group of raw coordinates a (x1,y1) and b (x2,y2) in step14are the real coordinates of two touch points A and B. The processor outputs the real coordinates a(x1, y1) and b(x2, y2) in step18.

FIGS. 7aand7bshow that two touch points C and D occur in two diagonal electrode areas. In step12, according to location and definition of the first A electrodes121and the first B electrodes122, processor can determine that the centroid x3is on the first A electrodes121and the centroid x4is on the first B electrodes122. In this situation, the result of step16is that only one centroid y3is computed in step15. Thus, in the two groups of raw coordinates c(x3,y3), d(x4,y4), c′(x3,y4), and d′(x4,y3), the group of raw coordinates c(x3,y3) and d(x4,y4) containing the real coordinate c(x3,y3) are the real coordinates of two touch points C and D. After step16, the process directly proceeds to step18, in which the processer outputs the real coordinates c(x3,y3) and d(x4,y4).

FIG. 8illustrates that two touch points E and F occur on the same electrode. In this situation, the determined result in step13of the process inFIG. 5is that only one centroid y5is computed, which presents that only two raw coordinates e(x5,y5) and f(x6,y6) are calculated in step12. Thus, these two raw coordinates are the real coordinates of two touch points E and F. After step13, the process directly proceeds to step18, in which the processer outputs the real coordinates e(x5, y5) and f(x6, y6).

Real coordinates of multiple touch points can be output to a control device or display for subsequent executions, which are not limited in the present invention.

By various designs of scanning circuit, Split Scanning Circuit may, each time, scan any of the first or second electrodes with switches connected to the scanned electrodes being closed and switches connected to the other electrodes being open. If more than one centroid is computed, the Split Scanning Circuit may repeat the process by scanning other electrodes of a different direction. For example, in step15, switches connected to the first B electrodes are closed, and the Split Scanning Circuit scans the first B electrodes while the other electrodes are open. if two centroids are computed, in step17, switches connected to the second B electrodes are closed, and the Split Scanning Circuit scans the second B electrodes while the other electrodes are open.

Real coordinates of multiple touch points can also be determined by using the method explained inFIG. 9. Similar to the method presented inFIG. 5, the process from step20to step23is the same as that from step10to step13. Nevertheless, when two centroids are computed in both the first direction X and the second direction Y, the processor does not divide raw coordinates, but instead, as in step24, the Split Scanning Circuit scans all electrodes namely the first A electrodes, the first B electrodes, the second A electrodes and the second B electrodes, in any order, with the switches, connected to the electrodes being scanned, being closed while other switches are open, to find out the real coordinates directly. After step24, the processor outputs the real coordinates in step25.

The processor mentioned above comprises a scanning unit, a computing unit and an outputting unit. The scanning unit is used to provide scanning signal to electrodes and receive electric signal (such as a signal representing the change in the self capacitance) generated during scanning of the electrodes. The computing unit performs the role of computing centroid and calculating projection. The results, such as the real coordinates of the touch points, are outputted by the outputting unit.

Method of determining real coordinates of two touch points mentioned above can also be utilized to determine real coordinates of more than two touch points. The Normal Scanning Circuit scans a plurality of electrodes both in a first direction and a second direction to detect raw coordinates of said touch points, and then the Split Scanning Circuit scans said electrodes to determine real coordinates of said touch points from said raw coordinates.

One of multiple touch points described above is located on at least one intersection of the first electrodes and second electrodes.

While certain embodiments have been shown and described, various modifications and substitutions may be made thereto without departing from the spirit and scope of the invention. Therefore, it is to be understood that the present invention has been described by way of illustration and not limitations.