PATENT DOCUMENT

Publication Number: US-9557845-B2
Application Number: US-201213560958-A
Country: US
Kind Code: B2

Title: Input device for and method of communication with capacitive devices through frequency variation

Abstract:
A computing device configured to receive data from a peripheral device, such as a stylus. The computing device includes a processor, a touch interface, such as a touch screen, in communication with the processor and configured to detect an input corresponding to an object approaching or contacting a surface. The computing device further includes a touch filter in communication with the touch interface and a peripheral filter in communication with the touch interface. The touch filter is configured to reject a peripheral frequency corresponding to a peripheral signal of the peripheral device and the peripheral filter is configured to reject a touch frequency component corresponding to a touch signal corresponding to a touch input.

Claims:
What is claimed is: 
     
       1. A computing device configured to receive data from a peripheral device, comprising:
 a processor; 
 a touch interface in communication with the processor and configured to detect an input corresponding to an object approaching or contacting a surface, the touch interface comprising a plurality of drive lines coupled via a multiplexer to drive circuitry and a plurality of sense lines coupled to sense circuitry; 
 a touch filter in the sense circuitry in communication with at least one of the plurality of sense lines and configured to reject a peripheral frequency corresponding to a peripheral signal of the peripheral device; 
 a first peripheral filter in the sense circuitry in communication with the at least one of the plurality of sense lines and configured to reject a touch frequency component corresponding to a touch signal corresponding to a touch input; and 
 a second peripheral filter in the drive circuitry in communication with at least one of the plurality of drive lines and configured to detect the peripheral signal of the peripheral device along the drive lines; 
 wherein the multiplexer is configurable to: 
 couple the drive lines to a stimulation signal in the drive circuitry when scanning the sense lines for the touch and peripheral signals: and 
 couple the drive lines to the second peripheral filter in the drive circuitry when scanning the drive lines for the peripheral signal when the peripheral signal is detected by the sense circuitry in response to the stimulation signal. 
 
     
     
       2. The computing device of  claim 1 , wherein the touch interface further comprises:
 a display screen in communication with the processor and configured to provide a visual output for the computing device. 
 
     
     
       3. The computing device of  claim 1 , wherein the peripheral signal and the touch signal are provided to the first peripheral filter and the touch filter, respectively, by the at least one of the plurality of sense lines. 
     
     
       4. The computing device of  claim 1 , wherein the touch interface further comprises one or more analog to digital converters, wherein the analog to digital converters are in communication with the touch filter and the first peripheral filter. 
     
     
       5. The computing device of  claim 1 , wherein the touch filter and the first peripheral filter receive the input from the touch interface substantially simultaneously. 
     
     
       6. The computing device of  claim 1 , wherein the touch filter is a band pass filter having a pass band set to a frequency corresponding to a frequency of the touch signal. 
     
     
       7. The computing device of  claim 6 , wherein the pass band of the touch filter ranges between 100 kHz to 10000 kHz. 
     
     
       8. The computing device of  claim 1 , wherein the first peripheral filter and the second peripheral filter are band pass filters having a pass band set to a frequency corresponding to a frequency of the peripheral signal. 
     
     
       9. The computing device of  claim 8 , wherein the pass band of the first and second peripheral filters ranges between 100 kHz to 2000 kHz. 
     
     
       10. A method for receiving digital data from a peripheral input device at a touch screen including a plurality of drive lines and a plurality of sense lines, the method comprising:
 scanning the plurality of sense lines, wherein the plurality of drive lines are coupled via a multiplexer to a stimulation signal when scanning the plurality of sense lines; 
 filtering a first signal received through one or more of the plurality of sense lines by a touch filter coupled to the one or more of the plurality of sense lines; 
 filtering the first signal by a first peripheral filter coupled to the one or more of the plurality of sense lines; 
 analyzing a touch output from the touch filter and a peripheral output from the first peripheral filter to determine whether the first signal is a touch signal or an input device signal; and 
 when the first signal is determined to be the input device signal:
 coupling, via the multiplexer, a second peripheral filter to one or more of the plurality of drive lines; 
 scanning the plurality of drive lines; and 
 filtering a second signal received through the one or more of the plurality of drive lines by the second peripheral filter. 
 
 
     
     
       11. The method of  claim 10 , wherein the input device signal is a modulated analog signal including digital data corresponding to the input device. 
     
     
       12. The method of  claim 10 , wherein the input device is a stylus. 
     
     
       13. The method of  claim 10 , wherein the first peripheral filter and the touch filter are band pass filters. 
     
     
       14. The method of  claim 13 , wherein a pass band of the first peripheral filter is different from a pass band of the touch filter. 
     
     
       15. The method of  claim 14 , wherein the first peripheral filter is configured to reject a bandwidth of frequencies falling within the pass band of the touch filter.

Description:
TECHNICAL FIELD 
     The present invention relates generally to computing devices, and more specifically, to input devices for computing devices. 
     BACKGROUND 
     Many types of input devices may be used to provide input to computing devices, such as buttons or keys, mice, trackballs, joysticks, touch screens and the like. Touch screens, in particular, are becoming increasingly popular because of their ease and versatility of operation. Typically touch screens can include a touch sensor panel, which may be a clear panel with a touch-sensitive surface, and a display device that can be positioned behind the panel so that the touch-sensitive surface substantially covers the viewable area of the display device. Touch screens allow a user to provide various types of input to the computing device by touching the touch sensor panel using a finger, stylus, or other object at a location dictated by a user interface being displayed by the display device. In general, touch screens receive a touch event and a position of the touch event on the touch sensor panel, and the computing system can then interpret the touch event in accordance with the display appearing at the time of the touch event, and thereafter can perform one or more actions based on the touch event. 
     Some capacitive sense touch sensor panels can be formed from a matrix of row and column traces, with capacitive sensing elements or nodes present where the rows and columns cross over each other while being separated by a dielectric material. Each row can be driven by a stimulation signal, and touch locations can be identified through changes in the stimulation signal. Typically, a touch location is sensed based on an interference of the stimulation signal, such that a touch location may correspond to a location where the stimulation signal is the weakest. 
     In some instances it may be desirable for input devices, such as styli, to be able to transfer data, in addition to the touch location data, to the touch screen. For example, a stylus may have a finer tip than a user&#39;s finger and may be better able to transmit fine characters or symbols (such as those used in handwriting) better than a user&#39;s fingers. As another example, data from sensors in the input device may enhance the user experience, with the touch screen, e.g., a sensor may transfer force input parameters to the touch screen to vary an output corresponding to the input device. However, in many instances, the touch screen may have difficulty detecting the input device and/or may not recognize the signal from the input device, and data communication between the touch screen and the input device may be difficult to implement. 
     SUMMARY 
     One example of the present disclosure may take the form of a computing device configured to receive data from a peripheral device, such as a stylus. The computing device includes a processor, a touch interface, such as a touch screen, in communication with the processor and configured to detect an input corresponding to an object approaching or contacting a surface. The computing device further includes a touch filter in communication with the touch interface and a peripheral filter in communication with the touch interface. The touch filter is configured to reject a peripheral frequency corresponding to a peripheral signal of the peripheral device and the peripheral filter is configured to reject a touch frequency component corresponding to a touch signal corresponding to a touch input. 
     Another example of the disclosure may take the form of a method for receiving digital data through a touch screen. The method may include scanning a plurality of sense lines, filtering a first signal received through one or more of the plurality of sense lines by a touch filter, filtering the first signal by a peripheral filter, and analyzing a touch output from the touch filter and a peripheral output from the peripheral filter to determine whether the first signal is a touch signal or an input device signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a system including a computing device and an input device configured to provide input data to the computing device. 
         FIG. 2  is an exemplary block diagram of the input device of  FIG. 1 . 
         FIG. 3  is a simplified cross-section view of a portion of a touch screen of the computing device taken along line  3 - 3  in  FIG. 1 . 
         FIG. 4  is a simplified block diagram of a sample touch screen or touch interface and associated circuitry. 
         FIG. 5  is an enlarged view of a node of the touch screen in communication with the input device. 
         FIG. 6  is a flow chart illustrating a method for using a touch screen to receive data from an input device. 
         FIG. 7  is a perspective view of a system including a computing device and two input devices configured to provide input data to the computing device. 
         FIG. 8  is a schematic of an illustrative implementation of the input devices, the touch screen, and associated circuitry of  FIG. 7 . 
         FIG. 9A  is a diagram of a sample sinusoidal waveform encoded by frequency modulation. 
         FIG. 9B  is a diagram of a sample sinusoidal waveform encoded with data by phase shifting. 
     
    
    
     SPECIFICATION 
     Overview 
     In some embodiments herein, an input device and methods for transmitting data from the input device through a capacitive coupling or touch screen interface are disclosed. In one embodiment, the input device, which may be a peripheral device, such a stylus, may transmit data to the touch screen. The input device may transmit data to the touch screen without requiring the input device to send an activation signal or otherwise “sniff” the touch screen to indicate to the touch screen that data is about to be transferred thereto. Rather, the input device may be the “master” and the touch screen may be the “slave,” which may allow the input device to transmit data as desired by the input device, which may result in more efficient data transmission between the two devices, and may eliminate the need for the touch screen to provide feedback to the input device. 
     In some embodiments, the touch screen may include one or more peripheral signal filters as well as one or more touch filters in communication with one or more sense lines for the touch screen. The peripheral filter may be one or more band pass filters with the pass band frequency set at a frequency corresponding to a frequency of an input signal (peripheral signal) from the input device. Additionally, the pass band of the peripheral filter is set at a frequency to reject touch signals (for example, from a user&#39;s finger) and environmental noise signals. Conversely, the touch filter may have a pass band that is narrow enough to reject the peripheral signal from the input device, as well as any environmental noise signals, but may have a bandwidth sufficiently wide to allow touch signals to be transmitted therethrough. 
     In these embodiments, when the touch screen receives an input, either from the input device or from a user&#39;s finger (or other user touch), the signal may be filtered by the peripheral signal and the touch filter. A processor in communication with the sense lines and the filters may analyze the output from each filter to determine if an input is a touch input or a peripheral input. In other words, if the signal passes through the touch filter the processor may determine that the received input was a touch signal, whereas if the signal passes through the peripheral filter, the processor may determined that the received input was a peripheral input. Because both user touches and touches by the input device may be filtered by the touch filter and the peripheral filter, the touch screen may simultaneously detect user touch inputs as well as any input signals from the input device. 
     Once the processor identifies a particular input signal as being an input from the input device, the touch screen may scan one or more drive lines. For example, the touch screen may multiplex one or more drive lines of the touch screen to receive additional data from the input device. In some instances, by scanning the drive lines the processor may be able to determine the horizontal location of the input device, and using the data from the sense lines may be able to determine the vertical location of the input device. Thus, by scanning the sense and drive lines, the x and y coordinates of the input device on the touch screen may be determined. Further, scanning the drive lines may allow the touch screen to receive additional data from the input signal of the input device. 
     The touch screen may be configured to receive an analog and/or digital signal from the input device. This may allow the input device to transfer data from one or more sensors (such as force sensors, accelerometers, gyroscopes, and so on) to the touch screen. Additionally, the touch screen may vary a displayed output, may provide different inputs to one or more applications, or the like based on the data received from the input device. As one example, the input device may include a force sensor that may sense a change in force experienced on a body of the input device, and this data may be transferred to the touch screen which may vary the thickness of a displayed line corresponding to the movements of the input device. 
     DETAILED DESCRIPTION 
     Turning now to the figures, a communication system including a computing device and an input device will be discussed in more detail.  FIG. 1  is a perspective view of an input system  100  including an input device  104  in communication with a computing device  102  by a touch screen  106 . The computing device  102  may be substantially any type of electronic device including a capacitive input mechanism, such as the touch screen  106  or other touch interface. For example, the computing device  102  may be a laptop computer, a tablet computer, a smart phone, a digital music player, portable gaming station, or the like. Although not shown, the computing device  102  may include one or more components of a typical electronic or computing device, such as a processor, to provide control or provide other functions for the device  102 . Some illustrative components for operating and communicating with the touch screen  106  are discussed in more detail below with respect to  FIG. 4 . 
     The computing device  102  may include the touch screen  106 , an enclosure  110 , and/or one or more input buttons  108 . The enclosure  110  encloses one or more components of the computing device  102 , as well as may surround and/or secure a portion of the touch screen  106  to the computing device  102 . The one or more input buttons  108  may provide input functions to the computing device  102 . For example, the input buttons  108  may adjust a volume for the computing device  102 , turn the computing device  102  on or off, or may provide other inputs for the computing device  102 . Further, the computing device  100  may also include one or more receiving ports  112 . The receiving ports  112  may receive one or more plugs or connectors, such as but not limited to, a universal serial bus (USB) cable, a tip ring sleeve connector, or the like. 
     The touch screen  106  may include one or more sensors in order to detect one or more input or location signals. Additionally, the touch screen  106  may include a display screen to provide a graphical user interface, and other video and/or image output for the computing device  102 . The touch screen  106  and other components of the computing device  102  will be discussed in more detail below. 
     Turning to  FIG. 2 , the input device  104  will be discussed in more detail. The input device  104  may be configured to be in communication with the computing device  102 , specifically through the touch screen  106 , discussed in more detail below.  FIG. 2  is an exemplary block diagram of the input device  104 . With reference to  FIGS. 1 and 2 , in some embodiments, the input device  104  may be in the form a stylus, and may have a generally elongated main body  124  with a tip  122  at a first end. The tip  122  may be configured to be traced along the touch screen  106 . For example, the tip  122  may be a generally resilient material, which may deform upon pressure, and can slide along the surface of the touch screen  106 . In another example, the tip  122  may be a relatively hard material and may be configured to roll along the surface of the touch screen. 
     The tip  122  may be a conductive material, or another material laced with a conductive material, in order to interact with the touch screen  106  and specifically one or more electrode layers (as discussed below) to provide input to the computing device  102 . Additionally, the tip  122  may be configured to transmit one more signals, such as voltage signals, to the touch screen  106 . For example, the tip  122  may be communicatively coupled to a power source  128 , which may provide one or more voltages to the tip  122  to transmit to the touch screen  106 . In one embodiment, the tip  122  may act as an electrode that may interact with the touch screen to stimulate an electric field. The tip  122  may be made of metals such as aluminum, brass or steel, as well as conductive rubber, plastic or other materials doped with conductive particles. 
     It should be noted that the input device  104  may include input components other than the tip that may transfer one or more signals to the touch screen. For example, the input device may include one or more input components positioned on the sides of the body  124  and/or the end of the input device. These components may be used to provide additional data to the touch screen. For example, the input device  104  may include an “eraser” component that may be positioned on the end of the device  104  opposite the tip  122 . The eraser may provide a signal that may be differentiated by the touch screen from a signal from the tip. As one example, the eraser signal may be phase or frequency shifted from the tip signal, which may allow the touch screen to identify the signal as being from the eraser. 
     With continued reference to  FIG. 2 , the input device  104  may also include one more sensors  126 . In some instances the sensors  126  may be configured to detect one more stimuli at the tip  122 , the body  124 , and/or other areas of the input device  104 . For example, the one more sensors  126  may include an accelerometer, a gyroscope, a pressure or force sensor, and so on. In these instances, the sensors  128  may be configured to detect changes in the angle a user may hold the input device  104 , a force that the user presses the tip  122  against the touch screen  106 , an acceleration of the tip  122  along the touch screen  106 , and so on. In some embodiments, the sensor  126  may provide a signal to the processor  130  in response to a sensed parameter, and the processor  130  may use that signal to activate the input device  104 . For example, the sensor  126  may be a force sensor that may activate the input device  104  when a user applies a force on the input device  104  (for example, by squeezing the body  124 , pressing the tip  122  to the touch surface, or the like). It should be noted that the power source  128  may further provide power to the one or more sensors  128 , as necessary or desired. 
     The input device  104  may also include one or more processing components to control select functions of the input device  104 . For example, the input device may include a processor  130  that may control certain functions of the sensors  128 . In some embodiments, the processor  130  may determine one or more input signals that may be transmitted through the tip  122  to the touch screen  106  and/or computing device  102 . Moreover, as discussed in more detail with respect to  FIGS. 8, 9A, and 9B , depending on the desired format of the data transfer between the input device and the touch screen, the input device may include other components, such as amplifiers, signal boosters, modulators, or the like. 
     Optionally, the input device  104  may also include an output circuitry or interface  132 . The output interface  132  may receive and/or transmit one or more signals to and from the input device  104 . For example, the output interface  132  may receive one or more radio signals (e.g., Bluetooth), or may be configured to receive one or more electrical (digital and/or analog) signals transmitted from the computing device  102 . In the latter example, the output interface  132  may be used in conjunction with or instead of the tip  122  to transmit and/or receive signals from the touch screen  106 . For example, the output interface  132  may be configured to receive one or more voltage signals from the touch screen  106  (e.g., through the drive lines). Additionally, the output interface  132  may include a voltage source in order transmit (optionally via the tip  122 ) one or more signals to the touch screen  106  and/or computing device  102 . 
     The touch screen  106  will now be discussed in more detail.  FIG. 3  is a cross-section view of the touch screen  106  taken along line  3 - 3  in  FIG. 1 . The touch screen  106  is configured to receive inputs from an object and send this information to a processor. Such information may be, for example, location information based on a user&#39;s finger or data from the input device. The touch screen  106  may report touches to the processor  148  and the processor  148  may interpret the touches in accordance with its programming. For example, the processor may initiate a task in accordance with a particular touch. The touch screen  106  may include a display screen  112  and a sensor panel  114  positioned at least partially over the display screen  112 . The display screen  112  is configured to display one or more output images and/or videos for the computing device  102 . The display screen  112  may be substantially any type of display mechanism, such as a liquid crystal display (LCD), plasma display, or the like. In instances where the display screen  112  is a LCD display, the display screen  112  may include (not shown) various layers such a fluorescent panel, one or more polarizing filters, a layer of liquid crystal cells, a color filter, or the like. It should be noted that  FIG. 3  is not drawn to scale and is a schematic view of the touch screen. For example, in some embodiments, there may be an air gap between the display  112  and the sensor glass  118 , although this gap is not illustrated in  FIG. 3 . 
     The sensor panel  114  may include an electrode layer  116  operably connected to a sensor glass  118  or other type of support structure. The electrodes  116  may be connected to one or both sides of the sensor glass  118 . As one example, the electrodes  116  may be positioned on a first side of the sensor glass  118 , and the other side of the glass may be coated to form a ground shield. As another example, the sensor glass  118  may be formed of multiple layers of polyethylene terephthalate (PET), with each layer including electrodes  116  operably connected to one side of the layer, and then each of the layers may be stacked to form rows, columns, and/or shield layers. 
     With continued reference to  FIG. 3 , the sensor glass  118  may form a portion of the display screen  112  or may be separate therefrom. The sensor glass  118  may be a relatively clear element that may protect the display screen  112  from forces that may be exerted on the sensor panel  114  by a user or input device. In some embodiments, the sensor glass  118  may be a clear glass panel that may allow the display screen  112  to be viewable therethrough. The electrode layer  116  may include one or more electrodes which may be deposited on the sensor glass  118 . For example, the electrode layer  116  may include transparent conductive materials and pattern techniques such as ITO and printing. It should be noted that the electrode layer  116  may include a plurality of electrodes separated by gaps, where the electrodes are interconnected by one or more traces or other electrical elements. 
     In some embodiments, the sensor glass  118  may act as a ground shield to electronically isolate the electrode layer  116  from the display screen  112  and/or other internal components of the computing device  102  (such a processor, or electronic circuits). The electrode layer  116  may include one or two layers of electrodes which may be spaced apart across the layer  116 . The electrodes, discussed in more detail with respect to  FIG. 4 , may define one or more nodes  144  that act as capacitive coupling sensors to detect touches on the touch screen  106 . The number and configuration of the nodes  144  may be varied, depending on the desired sensitivity of the touch screen  106 . 
     The touch screen  106  may also include a cover sheet  120  disposed over the electrode layer  116 . Thus, the electrode layer  116  may be substantially sandwiched between the cover sheet  120  and the sensor glass  118 . The cover sheet  120  protects the other layers of the touch screen  106 , while also acting to insulate the electrode layer  116  from external elements (such as fingers or input devices that may contact the cover sheet  120 ). The cover sheet  120  may generally be formed from substantially any suitable clear material, such as glass or plastic. Additionally, typically the cover sheet  120  should be sufficiently thin to allow for sufficient electrode coupling between the electrode layer  118  and any external input objects (e.g., fingers, input devices). For example, the cover sheet  120  may have a thickness ranging between 0.3 to 2 mm. 
     It should be noted that in some embodiments, the touch screen  106  may be substantially any type of touch interface. For example, the touch interface may not be see-through and/or may not correspond to a display screen. In these instances, a particular surface or group of surfaces may be configured to receive touch inputs, that may or may not correspond to a separately displayed user interface, icons, or the like. 
     Operation of the touch screen  106  during a touch scan will now be discussed in more detail. It should be noted that in the embodiments discussed herein, the touch screen may simultaneously search for user input touches as well as inputs from the input device. Thus, the term “touch scan” may encompass an input device scan as well, as those signals may also be detected during the touch scan.  FIG. 4  is an illustrative block diagram of the computing device  102  and touch screen  106 . The sensor panel  114  of the touch screen  106  may be configured to detect touches on the surface of the touch screen  106  by changes in capacitance. Typically when two electrically conductive members come close to one another, without actually touching, their electric fields interact to form a capacitance. With reference to  FIG. 4 , a sensing node  144  formed by one or more electrodes (explained below) may form a first electrically conductive member and an object, such as a finger of the user, may form a second electrically conductive member. The sensor panel  114  of the touch screen  106  may be configured as in a self capacitance arrangement or in a mutual capacitance arrangement. 
     In the self capacitance arrangement, the electrode layer  116  may include a single layer of a plurality of electrodes spaced in a grid or other arrangement where each electrode may form a node  144 . The sensing circuit  150  monitors changes in capacitance that may occur at each node  144 . These changes occur at a node  144  when a user places an object (e.g., finger or tip  122  of the input device  104 ) in close proximity to the electrode. 
     With continued reference to  FIG. 4 , in a mutual capacitance system, the electrode layer  116  may include electrodes separated into two layers forming drive lines  142  and sense lines  140 . The drive lines  142  may be formed on a first layer of the electrode layer  116  and the sense lines  140  may be formed on a second layer of the electrode layer  116 . The nodes  144  for the sensor panel  114  may be defined at locations of the electrode layer  116  where the drive lines  142  may cross over or under the sense lines  140  (although they are typically in different layers). The sense lines  140  may intersect the drive lines  142  in a variety of manners. For example, in one embodiment, the sense lines  140  are perpendicular to the drive lines  142 , thus forming nodes  144  with x and y coordinates. However, other coordinate systems can also be used, and the coordinates of the nodes  144  may be differently defined. 
     A drive controller  146  or other circuitry is connected to each of the drive lines  142 . The drive controller  146  provides a stimulation signal (e.g., voltage) to the drive lines  142 . The sensing circuit  150  is connected to each of the sense lines  140  and the sensing circuit  150  acts to detect changes in capacitance at the nodes  144 . During operation, the stimulation signal is applied to the drive lines  142  and due to the capacitive coupling between the drive lines  142  and sensing rows  140 , a current is carried through to the sense lines  140  at each of the nodes  144 . The sensing circuit  150  then monitors changes in capacitance at each of the nodes  144 . As with the self-capacitance, a change in capacitance at each of the nodes  144  typically occurs when a user places an object such as a finger in close proximity to the node  144  as the object typically steals a charge, affecting the capacitance of the node  144 . 
     In a specific embodiment, each drive line  140  may be driven separately, such that the drive controller  146  may selectively apply the stimulation signal to each row  153  or banks (groups) or rows of drive lines  142 . Each drive line  140  may be driven sequentially until the entire set of drive lines  142  has been driven. In some embodiments, the drive lines  142  may be driven in banks  155  or groups. For example, a certain number of rows  153  may form a bank  155 , and each row  153  in the bank  155  may be driven together. Although the drive lines  142  are driven individually (or in groups) the sensing circuit  150  may sense changes of capacitance along all of the sense lines  140  in parallel. In other words, each column  152  of sense lines  140  may be sensed substantially simultaneously. It should also be noted that, in some instances, a stimulation signal may be applied to the electrode layer  116  by the input device  104 , rather than, or in addition to the drive controller  146 . This will be discussed in more detail below, but briefly, the input device  104  may create a capacitive coupling within the electrode layer  116  and apply a voltage signal in order to induce a current through the sense lines  140  and the drive lines  142 . 
     In either the self-capacitance or mutual capacitance arrangements discussed above, the sensing circuit  150  can detect changes in capacitance at each node  144 . This may allow the sensing circuit  150  to determine when and where a user has touched various surfaces of the touch screen  106  with one or more objects. The sensing circuit  150  may include one more sensors for each of the sense lines  140  and may then communicate data to a processor  148 . In one example, the sensing circuit  150  may convert the analog capacitive signals to digital data and then transmit the digital data to the processor  148 . In other examples, the sensing circuit  150  may transmit the analog capacitance signals to the processor  148 , which may then convert the data to a digital form. Further, it should be noted that the sensing circuit  150  may include individual sensors for each sensing line  142  or a single sensor for all of the sense lines  140 . The sensing circuit  150  may report a location of the node  144 , as well as the intensity of the capacitance (or changed thereof) at the node  144 . 
     In some embodiments, the touch screen  106  may include one or more multiplexers. For example, the sensing circuit  150  may include a multiplexer configured to perform time multiplexing for the sense lines  140 . For example, during a touch scan the sensing circuit  150  may receive signals from each of the nodes  144  along the sense lines  140  at approximately the same time, and the multiplexer stores the incoming signals and then may release the signals sequentially to the processor  148  one at a time. 
     In addition to the multiplexers that may be used to process touch signals, the touch screen  106  may also include a drive multiplexer  152 . The drive multiplexer  152  may be in communication with the drive lines  142  to switch between a touch mode and a stylus or input device mode. As will be discussed in more detail below, if a signal from the input device is detected, the touch screen  106  may scan the drive lines  142  in order to receive data transmitted from the tip  122  of the input device  104 . In these embodiments, the drive controller  146  may further be configured to sense for signals on the drive lines  142  in order to detect a signal transmitted from the tip  122  of the input device. In some embodiments, the drive controller  146  may include components that may be substantially similar to the sense circuitry  150 , which may allow the drive controller  146  and the drive lines  142  to act as sense lines  140  and interact with the tip  122  of the input device  104  to receive one or more signals (e.g., voltage signals). In other words, rather than providing a stimulation signal to the drive lines  142 , when receiving an input signal from the input device  104 , the input signal may act as a stimulation signal to the drive lines  142  (in the form of a data transmission signal). For example, during a stylus mode the drive controller  146  and the sense circuitry  150  may both act as receivers to receive signals from the drive lines  142  and the sense lines  140 , respectively, whereas during typical touch mode the drive controller  146  may not generally receive any signals but may provide the stimulation signal to the drive lines  142 . 
     With continued reference to  FIG. 4 , the sense circuitry  150  may also include two or more signal filters. For example, the sense circuitry  150  and the drive controller  146  may each include a peripheral filter  154 ,  156 . The peripheral filters  154 ,  156  process signals sensed by the sense lines  140  and the drive lines  142  to isolate a signal from the input device  104 , if present. For example, the peripheral filters  154 ,  156  may be pass band filters that may have a pass band set to allow the input signal of the input device  104 , while at the same time rejecting at least a portion of signals generated due to touch events and/or environmental noise. Additionally, as will be discussed in more detail below, in some instances, the input signal may be encoded with digital data by including one or more modulations, such as frequency, phase, or amplitude modulation. In these examples, the pass band of the peripheral filters  154 ,  156 , may have a sufficiently wide bandwidth to allow for the modulations. In many instances the bandwidth may depend on the type of modulation used to encode digital data within the input signal. However, as a general range, the bandwidth required for some modulations may range between 200-600 KHz. 
     As will be explained in more detail below, the input device  104  may transmit an input signal at a frequency that may be distinct from an operating frequency of the drive controller  146 . In other words, the input signal may have a different frequency than the stimulation signal applied by the drive controller  146 , so that signals sensed by the sense lines  140  may be different for user input touch events as compared to input device touch events. However, it should be noted that in some embodiments, the input device  104  may have a frequency that may be the same as the operating frequency of the touch screen, but in these cases the input device  104  and the touch screen may need to negotiate signal transmission timing, or the like, in order to determine which signal is being received by the sense lines  140  at a particular moment. 
     It should be noted that the peripheral filter  156  may be placed into communication with the drive lines  142  when the drive multiplexer  152  switches into stylus mode. In other words, during a touch scan where the drive controller  146  may apply a stimulation signal to the drive lines  142 , the peripheral filter  156  may not be in communication with the drive lines  142 ; however, during stylus mode, the input device  104  may provide a stimulation signal to the drive lines  142 , and in these instances the peripheral filter  156  may be placed into communication with the drive lines  142 . 
     With continued reference to  FIG. 4 , the touch screen  106  may also include a touch filter  158 . The touch filter  158  may be in communication with the sense lines  140  and may be incorporated as part of the sense circuitry  150  or separate therefrom. The touch filter  158  processes signals received at the sense lines  140  to determine if a received signal falls within a range to be considered a user touch event. For example, the touch filter  158  may be a band pass filter that may have a pass band configured to receive signals within typical touch frequencies and reject frequencies from the input device  104  and/or environmental noise. The touch filter  158  may have a bandwidth with center frequency ranges between 100-1000 kHz. 
     It should be noted that although a touch filter  158  is not illustrated in  FIG. 4  as being incorporated in to the drive controller  146 , in some embodiments, the drive lines  142  may be in communication with a touch filter  158 . For example, some components of the drive controller  146  may be substantially the same as the sense circuitry  150  and the drive controller  146  may include a peripheral filter and a touch filter. 
     The touch screen  106  may further include one or more analog to digital converters (ADCs). For example, the sense circuitry  150  may be in communication with an ADC  160 , such that the sense circuitry  150  may provide signals from the sense lines  140  to the ADC  160  which may convert analog signals received from the sense lines  140  into digital signals and provide those digital signal to the processor  148 . In one example, the touch screen  106  may include a single ADC  160  for converting signals from the sense lines  140 . In this example, the outputs from the peripheral filter  154  and the touch filter  158  for each sense line  140  may be time multiplexed and then provided to the ADC  160 . In a second example, the touch screen  106  may include a first ADC for the peripheral filter  154  for each sense line  140  and a second ADC for the touch filter  158  for each sense line  140 . In this example, the separate ADCs may convert signals from each of the filters respectively. 
     Operation of the system  100  and the input device  104  interacting with the touch screen  106  will now be discussed in more detail.  FIG. 5  is an enlarged view of the tip  122  of the input device  104  providing an input signal to a node  144  of the touch screen  106 . With reference to  FIGS. 2 and 5 , the input device  104  may provide a voltage signal at the tip  122 , and that signal may be applied to the sense lines  140  and/or drive lines  142 . The voltage signal may be a waveform, such as, but not limited to, sinusoidal, square, trapezoidal, or triangular wave (see, e.g.,  FIGS. 9A and 9B ). Additionally, it should be noted that the voltage signal may be an analog signal and/or may include digital data encoded therein. For example, the voltage signal may include data encoded in the amplitude, phase, frequency, and/or shape. In some embodiments, the voltage signal may be a relatively narrowband frequency modulated and/or phase modulated signal. For example, the voltage signal may have a frequency shift of approximately 20 kHz and/or a phase shift of approximately 180 degrees that may include data encoded within each of the shifts. Illustrative embodiments for data transfer from the voltage signal in the tip  122  will be discussed in more detail below. However, with reference to  FIG. 5 , there may be a tip to drive line capacitance Cxd, a tip to sense line capacitance Cxs. The changes in the Cxd, Cxs, as well as the applied voltage signal may transfer data from the input device  104  through the drive and sense lines to the touch screen  106 . 
     The voltage signal from the input device  104  may be configured to be transferred at a frequency range that may be different from the frequency of the stimulation signal. In this manner, the peripheral filters  154 ,  156  may be able to separate the voltage signal from the input device from the stimulation signal, and thus distinguish between user touches and input device touches. That is, the peripheral filters  154 ,  156  may attenuate and/or reject any signal outside of the pass band range, such as touch inputs, while passing through signals within the pass band range, such as signals from the input device. 
     A method for using the touch screen to receive data from the input device will now be discussed in more detail.  FIG. 6  is a flow chart illustrating a method  200  for using the input device  104  to transmit information to the touch screen  106 . The method  200  may begin with operation  202  and the drive controller  146  may apply a stimulation signal to the drive lines  142 . The drive controller  146  may apply the stimulation signal to a single drive line  142 , a group of drive lines  142  (for example, a bank of drive lines), or may apply the stimulation signal to the entire set of drive lines  146 . In many embodiments the drive controller  146  may apply the stimulation signal to groups of drive lines  142 , and may stimulate the groups sequentially until all of the drive lines  142  have been stimulated. As briefly mentioned above, the stimulation signal may be selected to have a frequency that may be different from a frequency of the input signal from the input device  104 . 
     Once the stimulation signal has been applied to the drive lines  142 , the method  200  may proceed to operation  204 . In operation  204  the sense circuitry  150  may scan the sense lines  140 . As discussed above, when the stimulation signal is applied to the drive lines  142 , a current may be induced in the sense lines  140  and changes in capacitance may be detected by the sense circuitry  150 . Additionally, the input device  104  may also provide a stimulation signal to the sense lines  140 . That is, the input signal from the input device  104  may be a sufficient voltage to stimulate the sense lines  140 . Accordingly, during operation  204 , the sense circuitry  150  may receive signals from each of the sense lines  142 . 
     Once the signals from the sense lines  142  have been received, the method  200  may proceed to operation  206 . In operation  206  the touch filter  158  may process the signals from each channel or sense line  140 . As described above, the touch filter  158  may be a band pass filter with a bandwidth set to allow touch signals to be passed through, but to reject signals from the input device and/or environmental noise. Accordingly, in some embodiments, the touch filter  158  may output only signals that may be generated by a user providing one or more touches to the touch screen  106 . 
     Substantially simultaneously with operation  206 , the method  200  may also proceed to operation  208  and the peripheral filter  154  in the sense circuitry  150  may filter the sensed signals from the sense lines  140 . In other words, the sense circuitry  150  may provide the sensed signals from the sense lines  140  to the touch filter  158  and the peripheral filter  154  substantially simultaneously so that the two filters can filter the signals at the same time. However, it should be noted that in other embodiments, the touch filter and the peripheral filtering may be done at different times, e.g., in a multiplexed manner. Moreover, in some instances, the peripheral filter  154  and the touch filter  158  may receive the signals prior to those signals being filter by an analog filter such as the ADC  160 , or the peripheral filter  154  and the touch filter  158  may filter the received signals after the signals have been filtered by the ADC  160 , or another signal filtering combination (e.g., the peripheral filter  154  may receive signals from the ADC, whereas the touch filter provide signals to the ADC). 
     During operation  208 , the peripheral filter  154  may process the sensed signals to determine if the signals are from the input device or due to a user touch. For example, opposite of the touch filter, the peripheral filter is configured to reject signals having a frequency corresponding to a user touch, and allow only those signals having a frequency generally corresponding to the input device  104  signal. However, as briefly discussed above, because the signal from the input device may be encoded with digital data (for example, through frequency or phase modulation), the peripheral filter  154  may further be configured to have a bandwidth allowing the modulations in the input signal to still be output. In other words, the pass band bandwidth of the peripheral filter  154  may be sufficiently wide to allow for modulations in frequency and/or phase from the input signal, so that although certain parameters of the input signal may vary, the input signal may not be filtered out or rejected. 
     After operations  206 ,  208  and the signals sensed by the sense lines  140  have been filtered by both the touch filter  158  and the peripheral filter  154 , the method  200  may proceed to operation  210 . In operation  210 , the processor  148  may analyze the output from the touch filter and the peripheral filter to determine if the input device  104  is present. For example, if the output from the peripheral filter  154  is relatively small or otherwise is not present, the processor  148  may determine that the input device is not providing a signal to the touch screen. On the contrary, if the output from the peripheral filter  154  has a value other than zero, the processor  148  may determine that the input device  104  is providing the input signal to the touch screen. 
     If the input device  104  is present, the method  200  may proceed to operation  212 . In operation  212  the touch screen  106  may scan the drive lines  142 . As one example, the multiplexer  152  may disconnect the drive lines  142  from a voltage source of the stimulation signal, and may connect the drive lines  142  to one or more sensors. In some embodiments, the drive lines  142  may be scanned similarly to the sense lines  140 , that is, each of the drive lines may be analyzed to detect changes in a signal or capacitance. 
     Once the drive lines  142  have been scanned, the method  200  may proceed to operation  214 . In operation  214 , the signals from the drive lines  142  may be provided to the peripheral filter  156  in communication with the drive controller  146 . The peripheral filter  156  may filter the received signals to remove any user touch and/or environmental frequencies. It should be noted that by scanning the drive lines  142  to receive the input signal from the input device  104 , the touch screen  106  may receive position information along the drive lines as well as the sense lines. That is, while the input device  104  is transmitting a signal, when the sense lines are scanned, the touch screen  106  may determine the location of the input device  104  along a first axis, and when the drive lines are scanned, the touch screen may determine the location of the input device  104  along a second axis. Thus, the node  144  location of the input device  104  may be determined by scanning both the drive lines and the sense lines. This may be required, because unlike a touch scan and the application of the stimulation signal, the location of the input signal applied by the input device  104  with respect to the drive lines may not be known. 
     The filtered input device signal as provided by the peripheral filters  154 ,  156  may include data from the input device  104 . As descried above, the input device  104  may include one or more sensors  126  that may provide data at the touch screen  106 . Additionally, the input device  104  may also transfer data regarding the power level in the power source, and as mentioned above, the input signal may be used by the touch screen to determine the position of the input device. As such, the touch screen may receive a variety of data from the input device  104  which may be used to vary an output on the display  118 , be provided as inputs to one or more applications on the touch screen  106 , or the like. After operation  214 , or if the input device  104  is not present in operation  210 , the method  200  may return to touch mode and return to operation  202 . 
     Multiple Input Devices 
     In some embodiments, the touch screen  106  may be configured to receive data from two or more peripheral or input devices.  FIG. 7  is a top perspective view of the two input devices communicating with the touch screen  106 .  FIG. 8  is a schematic of an illustrative embodiment of the two input devices communicating with the touch screen illustrated in  FIG. 7 . In these embodiments, the first input device  104  may be used by a first user to provide input the computing device  102 , and the second input device  304  may be used substantially simultaneously with the first input device  104  by a second user or the same user. In this manner, two separate users may provide input to the computing device  102  through their own input devices  104 ,  304 , or a user may use two or more input devices  104 ,  304  to provide input to the computing device  102 . For example, using a drawing application or program, the first input device  104  may represent a first color that may be displayed on the screen or a first width brush and the second input device  304  may represent a second color and/or a second width brush. Alternatively, each of the input devices  104 ,  304  may be selectively modified by changing an input to the one or more sensors  126  (e.g., by a user varying the applied force, tilt, or the like of the respective device). 
     The second input device  304  may be substantially similar to the first input device  104 . For example, the second input device  304  may include one or more sensors  326 , a power source  328 , a tip  322 , and the like. Additionally, with reference to  FIG. 8 , both the input devices  104 ,  304  may include a signal generator  170 ,  370 , a timing logic component  172 ,  372 , a boost regulator component  174 ,  374 , and/or a transmission amplifier  173 ,  373 . These components may be varied in other implementations, but in the implementation illustrated in  FIG. 8 , these components may create the input signal for the respective input device  104 ,  304  and encode the signal (via modulation) to include data, and prepare the signal to be transferred to the touch screen. For example, in some instances, the transmission amplifier  173 ,  373  may be used to amplify the signal prior to transmission in order to assist the touch screen in receiving the input signal. 
     In instances where two or more input devices may be used to provide communication to the touch screen  106 , each input device  104 ,  304  may be configured to communicate with a different frequency from each other. In other words, an input signal transmitted from a tip  122 ,  322  of each input device  104 ,  304  may have different frequencies from each other and may have different frequencies from the stimulation signal of the touch screen  106 . In one embodiment, the touch screen may alternatively filter the signals from the sense lines  140  to detect the first input device and the second input device. For example, touch screen  106  may apply the stimulation signal to a first set of drive lines  142  and scan the sense lines  140  for any user touch inputs and/or for any inputs from the first input device  104 . Then, the touch screen  106  may apply the stimulation signal to a second set of drive lines  142  and scan the sense lines  140  and any user touch inputs and/or any inputs from the second input device  304 . In this method, the touch screen  106  may include two separate peripheral filters  154  for each input device, or may otherwise vary the pass band of the peripheral filter  154  based on the input device. This may be required, because as described above, the two input devices  104 ,  304  may have different operating frequencies, and therefore the pass band for the peripheral filters may need to be modified to be configured to accept frequencies within the range of a respective input device. 
     In some embodiments, each input device  104 ,  304  may include one or more defined frequencies. As a first example, the touch screen  106  may implement a pair procedure, which may allocate specific frequencies to select input device. For example, both input devices  104 ,  304  may be connected through a wire or other mechanism to the computing device, and the touch screen  106  or computing device may allocate a specific frequency or range of frequencies to each input device. After this initial pairing, each respective input device may use the selected frequency to transfer the input signals. As a second example, the input devices may be dynamically reprogrammable by a user, through a backdoor wireless communication channel to the computing device, or other mechanism. For example, the input device may be reprogrammed as soon as two or more input devices operating at the same or similar frequencies are detected. 
     With reference to  FIG. 8 , operation of an illustrative embodiment will now be discussed in further detail. Each input device  104 ,  304  may generate an input signal through a signal generator  170 ,  370 , the input signal from each device  104 ,  304  may be transmitted to the touch screen  106  through the respective tips  122 ,  322  of the devices  104 ,  304 . As the tip  122 ,  322  contacts the touch screen  106 , the voltage of the input signal may induce a current in the sense lines  140 , which may be detected by the sense circuitry  150 . In some embodiments, the touch screen  106  may interleave searching for each of the two input devices  104 ,  304 . For example, the first input device  104  may transmit at a first frequency and the second input device  304  may transmit at a second frequency, and between a touch scan where the touch screen may drive one or more of the drive lines  142 , the sense lines may be multiplexed to a first peripheral filter that may be configured to receive the first frequency. Then, after the next drive lines are scanned, the sense circuitry  150  may connect the sense lines  140  to a second peripheral filter. Alternatively, the output from the sense lines  140  may be transmitted substantially simultaneously to the first and second peripheral filters. 
     Once an input signal from one of the input devices  104 ,  304  is received, the signal may be transmitted to a peripheral demodulation component  176 . The demodulation component  176  may demodulate the signal to extract digital data transmitted through an analog voltage signal of the input devices  104 ,  304 . The digital data may then be transferred to a memory component  186  until the processor  148  or other element may need to use the data. The touch screen  106  may also then scan the drive lines  142  for the input device signal and provide any received data to the processor  148 . 
     Similarly, when a touch input is received, the touch filter  160  may transmit the filtered signal to a touch demodulation component  178 , a decoder  180 , and a multiple and accumulate component. After the touch signals are demodulated, they may be combined in the decoder  180  with the data from the drive lines  142 . The drive controller  146 , which may include a transmission component  188  for providing the stimulation signal to the drive lines  142 , may stimulate the drive lines  142  during a touch scan to induce a current in the sense lines  140  in order so that the sense lines  140  may be able to detect changes in capacitance at the nodes  144 . 
     It should be noted that the implementation illustrated in  FIG. 8  is meant as a single example only. As one example, in  FIG. 8  the ADC  160  is illustrated as a single component shared by the peripheral filter and the touch filter; however, in some instances, each of the filters may have their own ADC. Embodiments of the present disclosure may be implemented in a variety of manners, and the discussion of any particular component or structure is meant as illustrative and not limiting. 
     Examples of data transmission from the input device  104  to the touch screen  106  will now be discussed. The input device  104  may transmit data corresponding the one or more sensors  126 , as well as other characteristics of the input device  104 . For example, the input device  104  may transmit a power level remaining (e.g., battery level), tilt or angle relative to the touch screen  106 , input or user force on the input device, as well as other parameters. The type of data transferred may depend on the configuration of the input device, as well as a desired application or software executed by the touch screen. 
     The data signal or transmission signal from the input device  104  may be analog, digital, or a combination signal including both analog and digital characteristics. As briefly discussed above the input device  104  may transmit data in the form of a voltage signal to the touch screen  106 . The voltage signal may be encoded with one or more changes in frequency that may each represent data.  FIG. 9A  is a diagram of a sample sinusoidal waveform encoded by frequency modulation. However, it should be noted that other types of waveforms may be used as the carrier wave from the data. With reference to  FIG. 9A , digital data, such as readings from one or more sensors  126 , may be represented by two different frequencies of the carrier wave. For example, a first portion of the sine wave  232  may have a period P 1  and a second portion may have a period P 2 , such that during a first time period, the sine wave  232  may have a first frequency of 1/P 1  and during a second time period the sine wave  232  may have a second frequency of 1/P 2 . In this instance, the first frequency may represent a digital  0  and the second frequency may represent a digital  1 . 
     As another implementation, the input device  104  may encode digital data as phase changes in the signal transmitted from the tip  122  to the touch screen  106 .  FIG. 9B  is a diagram of a sample sinusoidal waveform encoded with data by phase shifting. With reference to  FIG. 9B , using phase shifting, the digital data may be represented by different phases or phase shifts of the carrier wave. For example, a sine wave  234  may, during a predetermined time period, have a first portion with a first phase, and a second portion with a second phase that is shifted (e.g., either 90° or 180°) from the first phase. In this manner, the portion of the sine wave  234  having the first phase may represent a digital  0  and the second portion of the sine wave  234  shifted from the first portion may represent a digital  1 . 
     It should be noted that in other embodiments, the data signal from the input device  104  may be otherwise encoded with digital data. For example, the data signal may be encoded through amplitude modulation, angle modulation (varying an angle of the carrier wave), or the like. In these instances, the touch screen and/or the input device may be differently configured, as desired. Further, shift keying, such as amplitude and/or frequency shift keying may further be used to transfer data to and from the input device and the touch screen. 
     CONCLUSION 
     The foregoing description has broad application. For example, while examples disclosed herein may focus on input devices, it should be appreciated that the concepts disclosed herein may equally apply to substantially any other type of communication between electronic devices. Similarly, although the input device and receiving unit may be discussed with touch screens, the devices and techniques disclosed herein are equally applicable to other types of capacitive coupling systems. Accordingly, the discussion of any embodiment is meant only to be exemplary and is not intended to suggest that the scope of the disclosure, including the claims, is limited to these examples.

Metadata:
Filing Date: 20120727
Publication Date: 20170131
Grant Date: 20170131
Priority Date: 20120727
Inventors: SHAHPARNIA SHAHROOZ
Assignee: APPLE INC
CPC Classifications: [{"code": "G06F3/03545", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/044", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0416", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/033", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/03545", "inventive": true, "first": true, "tree": "[]"}, {"code": "G06F3/04162", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0441", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0442", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0443", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/033", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0443", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0442", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/04162", "inventive": true, "first": false, "tree": "[]"}, {"code": "G06F3/0441", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 48795936