This application claims priority of No. 097129599 filed in Taiwan R.O.C. on Aug. 5, 2008 under 35 USC 119, the entire content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to the touch-control technology, and more particularly to a touch screen and a coordinate positioning method.
2. Related Art
Recently, due to the rapid development of the technology, handheld devices, such as a smart mobile phone, a digital personal assistant (PDA), a global position system (GPS) and the like, have become more and more popular. Because touch screens are used in the above-mentioned devices, the technology of the touch sensor becomes very important. In the prior art, the typically used touch sensor is a resistive sensor. This resistive sensor has to sense the coordinate on the screen according to the pressure. A liquid crystal display is usually used in the handheld device, and the resistive sensor further has to be overlapped with the liquid crystal display. So, when the liquid crystal display presses the resistive sensor, the liquid crystal display is correspondingly pressed. After a long period of time, the liquid crystal display may be thus damaged. In addition, the resistive sensor has the lower resolution, and the coordinate often cannot be positioned precisely.
In the prior art, another touch sensor corresponding to a capacitive touch panel is also adopted. At present, the capacitive touch panel is widely applied to the touch screen of the handheld device. However, four layout layers have to be adopted in the circuit layout of the touch board of the conventional capacitive touch panel.
In addition, the conventional capacitive touch panel further has still another structure, such as an indium tin oxide (ITO) glass structure with six layers.
However, the printed circuit board or the indium tin oxide (ITO) glass structure has to be configured into a two-dimensional plane so that the conventional capacitive touch panel may be applied to the sensing over the two-dimensional plane. Thus, the manufacturing procedure is complicated, and the cost requirement also becomes higher.
In view of this, it is therefore an objective of the present invention to provide a coordinate positioning method and a touch screen using the same, wherein two-dimensional plane coordinates are obtained by way of one-dimensional sensing. Thus, the sensing resolution is increased, and the manufacturing cost of a printed circuit board or an indium tin oxide (ITO) glass is lowered.
Another objective of the present invention is to provide a coordinate calibrating method of a touch screen for transferring coordinates of capacitive sensors into coordinates of a display panel.
The present invention achieves the above-identified or other objectives by providing a touch screen including a sensor array layer and a microprocessor. The sensor array layer includes M×N capacitive sensors, wherein M rows of the capacitive sensors are disposed along a first axis, and N columns of the capacitive sensors are disposed along a second axis. The microprocessor includes multiple pins correspondingly coupled to the capacitive sensors. When the touch screen is touched to change at least one of sensing values of the capacitive sensors in the sensor array layer, the microprocessor performs an interpolation calculation to determine a touched coordinate according to the sensing values sensed by the capacitive sensors.
In addition, the present invention provides a coordinate positioning method. The method includes the steps of: providing a touch screen; providing a sensor array layer, comprising M×N capacitive sensors, in the touch screen, wherein M rows of the capacitive sensors are disposed along a first axis, and N columns of the capacitive sensors are disposed along a second axis; providing a plurality of reference coordinates, each comprising a first axial coordinate and a second axial coordinate, to the capacitive sensors; and determining, when the touch screen is touched to change at least one of sensing values of the capacitive sensors in the sensor array layer, a touched coordinate by performing an interpolation calculation according to the sensing values sensed by the capacitive sensors and the first axial coordinate and the second axial coordinate of the corresponding reference coordinate.
The touch screen according to the preferred embodiment of the present invention, the touch screen further includes an electronic component layer and a grounding layer, wherein the grounding layer is disposed between the sensor array layer and the electronic component layer. In another embodiment, the touch screen further includes a first silicon oxide layer and a second silicon oxide layer, wherein the sensor array layer is disposed between the first silicon oxide layer and the second silicon oxide layer.
The spirit of the present invention is to provide a sensor array layer in a touch panel, wherein the sensor array layer has M×N capacitive sensors, M rows of the capacitive sensors are disposed along the first axis, N columns of the capacitive sensors are disposed along the second axis, and each capacitive sensor is coupled to a microprocessor. Thus, when the touch panel is touched, the sensing value of the capacitive sensor located at the corresponding position is changed, and the touched position may be obtained by way of calculation. Because the structure is obviously different from the conventional touch panel, the present invention only needs one sensing layer to perform the coordinate positioning, which has to be achieved in the prior art using two sensing layers. Thus, the sensing resolution is increased, and the manufacturing cost of the printed circuit board or the indium tin oxide (ITO) glass may be further reduced as compared with the prior art.
Further scope of the applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus are not limitative of the present invention.
The present invention will be apparent from the following detailed description, which proceeds with reference to the accompanying drawings, wherein the same references relate to the same elements.
When the finger of the human body or any conductive material does not contact with the capacitive touch screen, the capacitance of the capacitive sensor 50 is kept unchanged. Therefore, each capacitor sensing value received by the microprocessor 502 does not fluctuate. Generally speaking, the microprocessor 502 provides an initial value (BaseValue), which is typically equal to 0, to each corresponding capacitive sensor 50. When the finger or any conductive material contacts with the capacitive touch screen of this embodiment, the capacitor sensing values (ADCValue) corresponding to some of the contacted capacitive sensors 50 or the neighboring capacitive sensors 50 change, and the microprocessor 502 performs the following judgement:
(ADCValue−BaseValue)>Th,
wherein Th represents a threshold value.
When the value is judged as being greater than the threshold value, the microprocessor 502 judges that the finger or any conductive material has contacted with the capacitive sensor 50.
When it is judged that the capacitor sensing values corresponding to two neighboring capacitive sensors 50 are greater than the threshold value, an interpolation calculation is performed to obtain the touched coordinate of the object (e.g., the conductor or the finger). The interpolation calculation is listed in the following:
wherein X_position represents the judged X coordinate, i and i+1 respectively represent X coordinates of the neighboring capacitive sensors 50, K represents the capacitor sensing value sensed at the ith X coordinate, L is the capacitor sensing value sensed at the (i+1)th X coordinate, and S is a coordinate interval number (or a difference) between two X coordinates.
For example, it is assumed that the built-in coordinate interval number of the X coordinate is 32 in each capacitive sensor 50 of the capacitive touch screen. When the finger touches the portion between the capacitive sensors 50 located at the coordinates (1, 0) and (2, 0), the capacitor sensing value sensed by the capacitive sensor 50 located at the coordinate (1, 0) is 70, and the capacitor sensing value sensed by the capacitive sensor 50 located at the coordinate (2, 0) is 80. That is, the X coordinate is:
(70×1+80×2)×32÷(70+80)=49.067≈49.
When it is judged that the capacitor sensing values corresponding to two neighboring capacitive sensors 50 are greater than the threshold value, the interpolation calculation is performed to obtain the touched coordinate of the object (e.g., the conductor or the finger). The interpolation calculation is listed in the following:
wherein Y_position represents the judged Y coordinate, j and j+1 respectively represent Y coordinates of the neighboring capacitive sensors 50, K represents the capacitor sensing value sensed at the jth Y coordinate, L is the capacitor sensing value sensed at the (j+1)th Y coordinate, and S is a coordinate interval number (or a difference) between two coordinates.
For example, it is assumed that the built-in coordinate interval number of the Y coordinate is 40 in each capacitive sensor 50 of the capacitive touch screen. When the finger touches the portion between the capacitive sensors 50 located at the coordinates (1, 1) and (1, 2), the capacitor sensing value sensed by the capacitive sensor 50 located at the coordinate (1, 1) is 90, and the capacitor sensing value sensed by the capacitive sensor 50 located at the coordinate (1, 2) is 150. That is, the Y coordinate is:
Y_position=(90×1+150×2)×40→(90+150)=65.
The following assumptions are made before the coordinate transferring calculation is described. It is assumed that the symbols of the X coordinate and the Y coordinate of
The simultaneous equations may be expressed in the form of a matrix:
Therefore, a two-dimensional coordinate (Xo, Yo) is mapped and obtained by an inverse matrix operation:
According to the above-mentioned embodiments, it is obtained that the present invention only needs one sensor array layer to achieve the two-dimensional coordinate positioning, which only can be achieved using two sensing layers in the prior art.
A coordinate positioning method may be simply concluded according to the embodiment of the present invention.
In step S1300, the method starts.
In step S1301, a touch screen is provided.
In step S1302, a sensor array layer, which includes M×N capacitive sensors, is provided in the touch screen, wherein M rows of the capacitive sensors are disposed along a first axis, and N columns of the capacitive sensors are disposed along a second axis.
In step S1303, multiple corresponding reference coordinates are provided to the capacitive sensors. Each reference coordinate includes a first axial coordinate and a second axial coordinate, as shown in the coordinate system of
In step S1304, it is judged whether the touch screen is touched or not by the microprocessor 502 according to whether the capacitor sensing value of the capacitive sensor 50 is greater than the threshold value, for example, when the judged result is negative, the procedure goes back to step S1304 to perform the continuous judgement.
In step S1305, when the touch screen is touched to change at least one of sensing values of the capacitive sensors in the sensor array layer, an interpolation calculation is performed to determine a touched coordinate according to the sensing values sensed by the capacitive sensors, and the first axial coordinate and the second axial coordinate of the corresponding reference coordinate. The interpolation calculation has been mentioned in the above-mentioned embodiment, so detailed descriptions thereof will be omitted.
In step S1306, the method ends.
First, the gain adjustment is performed on the sensing values sensed by each row of capacitive sensors 50 with one row serving as one unit. For example, if the layout resistance of the sensing line coupled to the Ith row of capacitive sensors 50 is smaller than the layout resistance of the sensing line coupled to the (I+1)th row of capacitive sensors 50, then the Ith row of sensing values are greater that the (I+1)th row of sensing values. Therefore, the designed microprocessor 502 may make the (I+1)th row of gains be greater than the Ith row of gains such that suitable gains may be assigned to the capacitive sensor 50 according to the layout resistance, and the sensing values sensed by the capacitive sensors 50 may be close to one another or each other under the same touch condition.
Second, the threshold value adjustment is performed on the sensing values sensed by each row of capacitive sensors 50 with one row serving as one unit. As mentioned hereinabove, when the finger is placed on a sensing region, the microprocessor 502 obtains a sensing value (ADCVaule). So, when (ADCValue−BaseValue) is greater than the threshold value (Threshold), it is judged that the finger is placed on the sensing region. Therefore, in order to overcome the layout resistance, the microprocessor 502 may be designed with one row serving as one unit to adjust the threshold values (Threshold) corresponding to each row of capacitive sensors 50. For example, if the layout resistance corresponding to the Ith row of capacitive sensors 50 is smaller than the layout resistance corresponding to the (I+1)th row of capacitive sensors 50, then the sensing values corresponding to the Ith row of capacitive sensors 50 are greater than the sensing values corresponding to the (I+1)th row of capacitive sensors 50. Thus, suitable threshold values may be assigned to the capacitive sensors 50 according to different layout resistances by properly designing the built-in (I+1)th row of threshold values (Threshold I+1) of the microprocessor 502 to be smaller than the Ith row of threshold values (Threshold I) such that each row of capacitive sensors 50 may correctly judge whether the finger or the conductor contacts with or approaches to the capacitive sensors 50 or not.
In summary, the spirit of the present invention is to provide a sensor array layer in a touch panel, wherein the sensor array layer has M×N capacitive sensors, M rows of the capacitive sensors are disposed along the first axis, N columns of the capacitive sensors are disposed along the second axis, and each capacitive sensor is coupled to a microprocessor. Thus, when the touch panel is touched, the sensing value of the capacitive sensor located at the corresponding position is changed, and the touched position may be obtained by way of calculation. Because the structure is obviously different from the conventional touch panel, the present invention only needs one sensing layer to perform the coordinate positioning, which has to be achieved in the prior art using two sensing layers. Thus, the sensing resolution is increased, and the manufacturing cost of the printed circuit board or the indium tin oxide (ITO) glass may be further reduced as compared with the prior art.
While the invention has been described by way of examples and in terms of preferred embodiments, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications. Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications.
Number | Date | Country | Kind |
---|---|---|---|
97129599 A | Aug 2008 | TW | national |
Number | Name | Date | Kind |
---|---|---|---|
5463388 | Boie et al. | Oct 1995 | A |
5825352 | Bisset et al. | Oct 1998 | A |
20020093491 | Gillespie et al. | Jul 2002 | A1 |
20050041018 | Philipp | Feb 2005 | A1 |
20060279551 | Lii et al. | Dec 2006 | A1 |
20070008299 | Hristov | Jan 2007 | A1 |
20070074913 | Geaghan et al. | Apr 2007 | A1 |
20070284154 | Li et al. | Dec 2007 | A1 |
20090189866 | Haffenden et al. | Jul 2009 | A1 |
Number | Date | Country | |
---|---|---|---|
20100033449 A1 | Feb 2010 | US |