DEVICE FOR DETECTING TOUCH
The present invention is a touch detection panel that uses capacitance changes between electrodes and changes thereof to determine a position of touch. The touch panel can be used in commercial applications where using a finger, stylus, or other object is the desired method of interface with an electronic system. The touch panel includes conductive electrodes and conductive lines connecting the conductive electrodes. The conductive electrodes themselves can be made of opaque conductive material, substantially transparent conductive material, or transparent conductive material depending on the requirements of an application. One such material is a metal mesh. The Touch panel is connected to a controller that applies current and/or voltage to the touch panel and senses current and/or voltage from the touch panel to determine either single or multiple touch locations.
Human-machine interface has long been studied and different methods have been developed to interface with machines. Entering characters on a keyboard is one way of entering information into a machine. Mice are also used to move a cursor on a screen and point to a certain area to enter information. Combination of keyboard and mice entries can be replaced by touch panels that are either overlaid or embedded on a display device or a mouse pad to enter information to a machine. Touch panels detect the object touching the surface of the touch panel and produce a signal that indicates the position of a touch. There are different touch technologies including resistive, capacitive, projected capacitive, acoustic, force and optical.
Currently the most popular technology is a projective capacitive technology due to its ability to provide multiple touches, meaning if several objects touch the touch panel the locations of all the objects can be determined either simultaneously or in a very short period of time from each other.
Multiple touch projective capacitive touch panels detect the change in current due to change in capacitance. When an electrode line of a capacitive touch panel is driven by a current source, all capacitances on those electrodes are charged. The charging time changes depending upon the number of electrodes and the resistance of the given line on a given axis. As the touch panel gets larger, an increasing number of electrodes are needed per axis to provide proper resolution. As the number of electrodes increases, the resistance increases therefore increasing the charging time. Increased charging time reduces the speed of the touch panel circuit.
SUMMARY OF THE INVENTIONOne objective of the invention is to reduce the charging time on a given axis for a capacitive touch panel therefore increasing the response time.
Another object of the invention is to provide a touch panel with a better visual performance while reducing the resistance of electrodes.
Another object of the invention is to manufacture a touch panel wherein all electrodes with lower resistance are placed on the same layer of a substrate and self capacitances or mutual capacitances or the combination of both self capacitance and mutual capacitances are used to determine the location of a touch.
Another object of the invention is to build a touch panel wherein a plurality of capacitances on a surface are used to determine a single or multiple touch locations.
Another object of the invention is to provide a touch panel wherein as the size increases, regardless of the touch panel structure, the speed of the touch panel is kept at an acceptable level.
Another object of the invention is to provide a formula for designing a touch panel wherein proper variables are used to change the touch panel design that is sensitive to touches on its surface.
Each conductive electrode 6 has a self capacitance between conductive electrode 6 and the ground. Likewise each conductive electrode 5 has a self capacitance between conductive electrode 5 and the ground. A self capacitance in this invention is defined as a capacitance between a conductor and the ground. A self capacitance depends on the size of the conductor and the permittivity of the conductor. It is also determined by the distance between the conductor and the ground. There also exists mutual capacitance between conductive electrode 6 and conductive electrode 5. Mutual capacitance is determined by three variables among other things. The distance between conductive electrode 5 and conductive electrode 6, the area between the conductive electrode 5 and conductive electrode 6 and the permittivity of the material used to build conductive electrode 5 and conductive electrode 6.
Touch panel 80 can detect touches on substrate 1 by using different techniques. In the first technique, controller 4 applies a current at a predetermined fundamental frequency to conductive assembly 3. The current is applied to one conductive assembly 3 at a time in sequence. While current is applied to one of the conductive assemblies 3, conductive assemblies 2 in the horizontal direction are sensed in a sequence. Once all the conductive assemblies 2 in horizontal direction are sensed, a current is applied to next conductive assembly 3 and then all conductive assemblies 2 are sensed in sequence. This process is repeated so that a map of capacitance distribution of touch panel 80 is calculated and stored in controller 4. This mapping of the touch panel is important because there are many stray capacitances caused by the touch panel structure and other neighboring structures. By mapping the touch panel 80, all the current capacitances captures while there is no touch on the surface. If a touch occurs, the capacitance at the point of touch will alter the capacitance at that point and as a result, the current sensed from that line will change. Controller 4 detects this change and determines the touch location based on this change.
An alternative method of increasing signal to noise ratio is to model touch panel 80 as a band pass filter (BPF). It has many self and mutual capacitances and conductive resistances built on the panel. When a current is applied to conductive assembly 3, certain amount of current will pass to conductive assembly 2 based on the filter characteristics. Therefore it is important to find the optimum frequency for the signal applied to touch panel 80 based on the filter characteristics. The filter characteristics can be best recognized by applying signals with different frequencies to touch panel 80 and measuring the output to determine the filter characteristics. This way, an amplitude versus frequency graph can be obtained and saved in the storage in controller 4 for each conductive assembly 3 and conductive assembly 2. By knowing these many curves, an optimum input frequency can be identified to provide the best signal to noise ratio. The system is adaptive in that during the normal operation of touch panel 80, a current with a certain frequency is applied to each conductive assembly 3. The frequency of the current applied to each individual conductive assembly in the vertical direction may be the same or similar or different based on the filter characteristic is obtained. When current is applied to one of the conductive assemblies 3, conductive assemblies 2 are sensed in a sequence. Alternatively a current with a certain frequency may be applied to each conductive assembly 2. The frequency of the current applied to each individual conductive assembly in the vertical direction may be the same or similar or different based on the filter characteristic is obtained. When current is applied to one of the conductive assemblies 2, conductive assemblies 3 are sensed in a sequence. By knowing the filter characteristics of touch panel 80, each conductive assembly is driven with a current with an optimum frequency based on the filter characteristics and therefore an optimum signal to noise ratio is obtained at the output of sensing conductive assemblies.
Metal mesh used in this invention can be any conductive metal including metal nanowires or micro wires.
Claims
1. A touch panel comprising:
- a substrate;
- a plurality of first conductive assemblies placed on a surface of the substrate in a first direction;
- a plurality of second conductive assemblies placed on the surface of the substrate in a second direction;
- wherein the first direction is substantially perpendicular to the second direction;
- wherein each first conductive assembly comprises a plurality of first conductive electrodes and a plurality of first conductive lines connecting the plurality of first conductive electrodes;
- wherein each second conductive assembly comprises a plurality of second conductive electrodes and a plurality of second conductive lines connecting the plurality of second conductive electrodes;
- a plurality of insulators placed between the plurality of first conductive lines and plurality of second conductive lines;
- wherein a controller applies an alternating current at a predetermined frequency to the plurality of second conductive assemblies or to the plurality of first conductive assemblies;
- wherein the touch panel is modeled as a band pass filter, and the frequency of the alternating current is determined based on filter characteristics of the band pass filter;
- wherein the controller senses the current from the plurality of first conductive assemblies if the current is applied to the plurality of second conductive assemblies;
- wherein the controller senses the current from the plurality of second conductive assemblies if the current is applied to the plurality of first conductive assemblies;
- wherein a first map containing either voltage or current or capacitance values at different locations on the surface of the touch panel is generated when there is no touch on the surface of the touch panel, and when there is a touch on the touch panel a second map is generated containing either voltage or current or capacitance values at similar locations as in the first map, and the second map and the first map are compared to determine the touch location on the surface of the touch panel.
2. The touch panel of claim 1, wherein the frequency of the alternating current is determined by using the distance between the first conductive electrodes and the second conductive electrodes, the resistance of the conductive material used to build the first conductive electrodes and the second conductive electrodes, the area between the first conductive electrodes and the second conductive electrodes and the permeability of the material used to build the first conductive electrodes and the second conductive electrodes;
3. The touch panel of claim 1, wherein the substrate is made of a transparent material.
4. The touch panel of claim 2, wherein the first group of conductive electrodes are made of a material that is selected from a group consisting of transparent material, opaque material and metal mesh.
5. The touch panel of claim 3, wherein the second group of conductive electrodes are made of a material that is selected from a group consisting of transparent material, opaque material and metal mesh.
6. The touch panel of claim 4, wherein the plurality of first conductive lines and the plurality of second conductive lines are made of a material that is selected from a group consisting of transparent material, opaque material and metal mesh.
7. The touch panel of claim 5 wherein if the plurality of first conductive lines and the plurality of second conductive lines are made of metal mesh, then the plurality of insulators are used between individual metal lines in the first direction and individual metal lines in the second direction.
8. The touch panel of claim 1 wherein the alternating current is applied to the first group of conductive assemblies in a sequential manner and the output of the second group of conductive assemblies are measured sequentially such that when a current is applied to a first conductive electrode assembly of the first group of conducive electrode assemblies, the output of each conductive electrode assembly of the second group of conductive electrode assemblies is measured in a sequential manner, and for the current applied to each conductive electrode assembly of the first group of conductive electrode assemblies, the outputs of the second group of conductive electrode assemblies are measured sequentially; wherein any change in output of the second group of conductive electrode assemblies corresponds to a touch, wherein the touch is located between a conductive electrode of the first group of conductive electrode assemblies and a conductive electrode of the second group of conductive electrode assemblies.
9. A touch panel comprising:
- a substrate;
- a plurality of first conductive assemblies placed on a surface of the substrate in a first direction;
- a plurality of second conductive assemblies placed on a separate surface of the substrate second direction;
- wherein the first direction is substantially perpendicular to the second direction;
- wherein each first conductive assembly comprises a plurality of first conductive electrodes and a plurality of first conductive lines connecting the plurality of first conductive electrodes;
- wherein each second conductive assembly comprises a plurality of second conductive electrodes and a plurality of second conductive lines connecting the plurality of second conductive electrodes;
- wherein a controller applies an alternating current having a predetermined frequency to the plurality of second conductive assemblies or to the plurality of first conductive assemblies;
- wherein the controller senses the current from the plurality of first conductive assemblies if the current is applied to the plurality of second conductive assemblies;
- wherein the controller senses the current from the plurality of second conductive assemblies if the current is applied to the plurality of first conductive assemblies;
- wherein the frequency of the alternating current is determined by using the distance between the first conductive electrodes and the second conductive electrodes, the area between the first conductive electrodes and the second conductive electrodes, the area between the first conductive lines and the second conductive lines, the resistance of the conductive material used to build the first conductive electrodes, the resistance of the conductive material used to build the second conductive electrodes, the resistance of the conductive material used to build the first conductive lines, the resistance of the conductive material used to build the second conductive lines, and the permittivity of the material used to build the first conductive electrodes and the second conductive electrodes.
10. The touch panel of claim 9, wherein the substrate is made of a transparent material.
11. (canceled)
12. The touch panel of claim 9, wherein the first group of conductive electrodes are made of a material that is selected from a group consisting of transparent material, opaque material and metal mesh.
13. The touch panel of claim 9, wherein the second group of conductive electrodes are made of a material that is selected from a group consisting of transparent material, opaque material and metal mesh.
14. The touch panel of claim 10 wherein the plurality of first conductive lines and the plurality of second conductive lines are made of a material that is selected from a group consisting of transparent material, opaque material and metal mesh.
15. (canceled)
16. The touch panel of claim 9, wherein the alternating current is applied to the first group of conductive assemblies in a sequential manner and the output of the second group of conductive electrodes are measured sequentially such that when a current is applied to a first conductive assembly of the first group of conductive assemblies, the output of each conductive assembly of the second group of electrodes is measured in a sequential manner, and for the current applied to each conductive electrode of the first group of conductive electrodes, the outputs of the second group of electrodes are measured in sequentially; wherein any change in output of the second group of conductive electrodes corresponds to a touch, wherein the touch is located between a conductive electrode of the first group of conductive electrodes and a conductive electrode of the second group of conductive electrodes.
17. A touch panel comprising:
- a substrate;
- a touch circuit placed on a surface of the substrate; the touch circuit comprising: plurality of first conductive assemblies placed on a surface of the substrate in a first direction;
- a plurality of second conductive assemblies placed on the surface of the substrate in a second direction;
- wherein the first direction is substantially perpendicular to the second direction;
- wherein each first conductive assembly comprises a plurality of first conductive electrodes and a plurality of first conductive lines connecting the plurality of first conductive electrodes;
- wherein each second conductive assembly comprises a plurality of second conductive electrodes and a plurality of second conductive lines connecting the plurality of second conductive electrodes;
- wherein a controller applies an alternating current at a predetermined frequency to the plurality of second conductive assemblies or to the plurality of first conductive assemblies;
- wherein the touch panel is modeled as a band pass filter, and the frequency of the alternating current is determined based on filter characteristics of the band pass filter;
- a plurality of insulators placed between the plurality of first conductive lines and plurality of second conductive lines.
18. The touch panel of claim 17 wherein a controller applies an alternating current at a predetermined frequency to the plurality of second conductive assemblies or to the plurality of first conductive assemblies; and wherein the controller senses the current from the plurality of first conductive assemblies if the current is applied to the plurality of second conductive assemblies.
19. The touch panel of claim 18, wherein the frequency of the alternating current is determined based on filter characteristics of each conductive electrode assembly.
20. The touch panel of claim 17, wherein the substrate is made of a transparent material.
21. The touch panel of claim 17, wherein the first group of conductive electrodes are made of a material that is selected from a group of conductive electrodes are made of a material that is selected from a group consisting of transparent material, opaque material and metal mesh.
22. The touch panel of claim 18, wherein the second group of conductive electrodes are made of a material that is selected from a group consisting of transparent material, opaque material and metal mesh.
23. The touch panel of claim 19 wherein the plurality of first conductive lines and the plurality of second conductive lines are made of a material that is selected from a group consisting of transparent material, opaque material and metal mesh.
24. The touch panel of claim 20 wherein if the plurality of first conductive lines and the plurality of second conductive lines are made of metal mesh, then the plurality of insulators are used between individual metal lines in the first direction and individual metal lines in the second direction.
25. The touch panel of claim 17 wherein the alternating current is applied to the first group of conductive assemblies in a sequential manner and the output of the second group of conductive assemblies are measured sequentially such that when a current is applied to a first conductive electrode assembly of the first group of conductive electrode assemblies, the output of each conductive electrode assembly of the second group of conductive electrode assemblies is measured in a sequential manner, and for the current applied to each conductive electrode assembly of the first group of conductive electrode assemblies, the outputs of the second group of conductive electrode assemblies are measured sequentially; wherein any change in output of the second group of conductive electrode assemblies corresponds to a touch, wherein the touch is located between a conductive electrode of the first group of conductive electrode assemblies and a conductive electrode of the second group of conductive electrode assemblies.
26. The touch panel of claim 17, wherein a black mask is placed at the periphery of the same surface as the touch circuit.
Type: Application
Filed: Dec 31, 2014
Publication Date: Jun 30, 2016
Inventor: Nihat Deniz Bayramoglu (Henderson, NV)
Application Number: 14/588,354