Abstract:
A capacitive sensing device and method include a touch surface, a capacitive touch sensor coupled to the touch surface and configured to measure finger motion along the touch surface, and a processor in operative communication with the capacitive touch sensor. The processor is configured to generate a scrolling command in response to finger motion along the touch surface, cease the scrolling command without substantially continuing generating the scrolling command upon the finger lifting from the touch surface when the finger is stationary prior to lifting from the touch surface, and continue generating the scrolling command for a time after the finger lifting from the touch surface to emulate coasting responsive to finger motion prior the finger lifting.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. patent application Ser. No. 12/880,805 filed Sep. 13, 2010, which is a continuation of U.S. patent application Ser. No. 11/253,477 filed on Oct. 18, 2005 (now U.S. Pat. No. 7,817,135), which is a continuation of U.S. patent application Ser. No. 10/382,799, filed Mar. 5, 2003 (now U.S. Pat. No. 7,212,189), which is a continuation of U.S. patent application Ser. No. 09/971,181, filed Oct. 4, 2001, which is a divisional of U.S. Pat. No. 6,587,093, filed Nov. 3, 2000, which claims priority to U.S. Provisional Application Ser. No. 60/163,635, filed Nov. 4, 1999. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    This patent discloses a computer mouse implemented partially or wholly using capacitive sensors. Pointing devices are an essential component of modern computers. One common type of pointing device is the mouse. Computer mice have been well known for many years. U.S. Pat. No. 3,541,541 to Engelbart discloses an early mouse implementation using either potentiometers or wheels with conductive patterns to measure the motion. The conductive patterns on these wheels are measured by direct electrical contact. Direct electrical contact to moving objects has many well-known disadvantages, such as increased friction, and wear and corrosion of contacts. 
         [0003]    Modern mice follow a plan similar to that of U.S. Pat. No. 4,464,652 to Lapson et al, with a rolling ball mechanically coupled to optical rotary motion encoders. The mouse also includes one or several buttons that operate mechanical switches inside the mouse. Recent mouse designs also feature a wheel for scrolling; U.S. Pat. No. 5,530,455 to Gillick et al discloses a mouse with a scroll wheel mechanically coupled to another optical rotary encoder. Such mechano-optical mice are widely used and well understood, but they do suffer several drawbacks. First, as moving parts they are susceptible to mechanical failure and may need periodic cleaning. Second, they are exposed to dirt, moisture, and other contaminants and environmental effects. Third, as low-cost mechanical devices they may be less sensitive to fine movements than fully electronic devices. Fourth, electromechanical sensors may be more expensive than purely electronic sensors. And fifth, optical sensors draw a significant amount of power due to their use of light emitting diodes. 
         [0004]    Another well-known type of mouse measures motion by direct optical sensing of the surface beneath the mouse. U.S. Pat. No. 4,364,035 to Kirsch discloses an optical mouse that worked with patterned surfaces, and U.S. Pat. No. 5,907,152 to Dandiker et al discloses a more sophisticated example that works with natural surfaces. U.S. Pat. No. 5,288,993 to Bidiville et al discloses a pointing device which includes a rotation ball but measures the rotation of the ball by purely optical means. Optical mice eliminate the difficulties associated with moving parts in the motion sensor, but even they must typically use mechanical mouse buttons and a mechanical scroll wheel. 
         [0005]    Many alternatives to scroll wheels have been tried. U.S. Pat. No. 5,883,619 to Ho et al discloses a mouse with a four-way scrolling button. U.S. Pat. No. 5,313,229 to Gilligan et al discloses a mouse with a thumb-activated scrolling knob. U.S. Pat. No. 5,122,785 to Cooper discloses a mouse that is squeezed to initiate scrolling. The ScrollPoint Mouse from International Business Machines includes an isometric joystick for scrolling, and the ScrollPad Mouse from Fujitsu includes a resistive touch sensor for scrolling. The proliferation of such devices shows both that there is a need for a good scrolling device for use with mice, and that none of the technologies tried so far are completely satisfactory. 
         [0006]    Capacitive touch pads are also well known in the art; U.S. Pat. No. 5,880,411 discloses a touch pad sensor and associated features. Touch pads can simulate the motion detector and buttons of a mouse by measuring finger motion and detecting finger tapping gestures. Touch pads can also be used for scrolling, as disclosed in U.S. Pat. No. 5,943,052. Capacitive touch pads are solid state electronic devices that avoid many of the pitfalls of mechanical sensors. However, many users prefer mice over touch pads for reasons of ergonomics or familiarity. 
         [0007]    Capacitive touch sensors for use as switches are well known in the art. For example, U.S. Pat. No. 4,367,385 to Frame discloses a membrane pressure switch that uses capacitance to detect activation. U.S. Pat. No. 5,867,111 to Caldwell et al discloses a capacitive switch that directly detects the capacitance of the user. The circuits of the &#39;411 patent already cited could also be used to implement a capacitive switch. Applications of capacitive switches to mice are relatively rare, but in the paper “Touch-Sensing Input Devices” (ACM CHI &#39;99, pp. 223-230), Hinckley and Sinclair disclose an experimental mouse with capacitive touch sensors to detect the presence of the user&#39;s hand on or near various mouse controls. 
         [0008]    U.S. Pat. No. 5,805,144 to Scholder et al discloses a mouse with a touch pad sensor embedded in it. However, Scholder only considers resistive and thermal touch sensors, which are less sensitive and less able to be mounted within the plastic enclosure of the mouse than capacitive sensors. Scholder suggests using the touch sensor in lieu of mouse buttons, but does not consider the use of the touch sensor for scrolling. 
         [0009]    The purpose of the present invention is to create a device with the familiar form and function of a mouse, wherein some or all of the mechanical functions of the mouse have been replaced by capacitive sensors. 
       SUMMARY 
       [0010]    The present invention is directed toward a capacitive sensing device for effecting a user interface action based on the measured variations of capacitance. In an embodiment, the device includes a touch surface, a capacitive touch sensor coupled to the touch surface and configured to measure finger motion along the touch surface, and a processor in operative communication with the capacitive touch sensor. The processor is configured to: generate a scrolling command in response to finger motion along the touch surface; cease the scrolling command without substantially continuing generating the scrolling command upon the finger lifting from the touch surface when the finger is stationary prior to lifting from the touch surface; and continue generating the scrolling command for a time after the finger lifting from the touch surface to emulate coasting responsive to finger motion prior the finger lifting. 
         [0011]    The disclosed device is directed towards a computer mouse. The computer mouse comprises a touch sensor embedded within a surface material of the mouse. The touch sensor is configured to measure motion of a finger along an axis. The touch sensor is configured to operate by capacitive means. 
         [0012]    Another embodiment disclosed includes a pointing device. The pointing device comprises a computer mouse configured to generate cursor commands. A touch sensor is coupled to the computer mouse. The touch sensor is configured for measuring motion of a finger along an axis. The touch sensor is configured for operating by capacitive means. A processor is in operative communication with the touch sensor. The processor is configured to generate a scrolling command in response to the motion of the finger along the axis. The processor is configured to continue generating the scrolling command responsive to the finger lifting from the touch sensor. 
         [0013]    Another embodiment disclosed includes a touch input system. The touch input system comprises a capacitive touch sensor configured for measuring motion of a finger along an axis. A processor is in operative communication with the capacitive touch sensor. The processor is configured to generate quadrature signals compatible with those from an optical rotary motion encoder in response to the motion of the finger along the axis. 
         [0014]    Yet another embodiment disclosed includes a one-axis touch sensor configured for sensing an object along a single axis. The one-axis touch sensor is configured to generate a scrolling signal responsive to sensing motion of the object touching the one-axis touch sensor. 
         [0015]    Still another embodiment disclosed includes a one-axis touch sensor comprising a sensor configured to sense along a single axis. The sensor is configured to generate a quadrature signal responsive to an object touching the sensor. The quadrature signal including characteristics of signals being of the type produced by a rotary encoder. 
         [0016]    Still another embodiment disclosed includes a one-axis touch sensor comprising a sensor configured to sense a finger along a single axis of the one-axis touch sensor. A processor is in operative communication with the sensor. The sensor is configured to transmit to the processor one of a touch signal responsive to motion of the finger touching the sensor, and a lift signal responsive to lift off of the finger from the sensor. The processor is configured to generate a scrolling signal responsive to the touch signal and the lift signal. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING FIGURES 
         [0017]      FIG. 1A  is a side plan view of a mouse typical of the prior art; 
           [0018]      FIG. 1B  is a top plan view of a mouse typical of the prior art; 
           [0019]      FIG. 2A  is a schematic view of a typical prior art rotary encoder; 
           [0020]      FIG. 2B  is a partial side plan view of a rotary disk and light detector employed by mice of the prior art; 
           [0021]      FIG. 2C  is a digital quadrature waveform generated by the rotary disk of  FIG. 2B ; 
           [0022]      FIG. 2D  shows an alternative waveform to that of  FIG. 2C ; 
           [0023]      FIG. 3A  is a schematic view of a rotary encoder that operates on capacitive principles rather than that which operates on optical principles as depicted in  FIG. 2A ; 
           [0024]      FIG. 3B  is a partial side plan view of a notched disk and related capacitance detector; 
           [0025]      FIG. 3C  is a depiction of a waveform as generated by the notched disk and capacitance detector of  FIG. 3B ; 
           [0026]      FIGS. 3D and 3E  are depictions of waveforms as generated by the notched disk and capacitance detector of  FIG. 3B  where the capacitance plates rotate in an opposite direction to that of  FIG. 3C ; 
           [0027]      FIG. 4  is a partial schematic side view of a capacitive rotary encoder for use herein; 
           [0028]      FIG. 5  is a partial side plan view of a rotary encoder as an enhancement of the encoder depicted in  FIG. 3A ; 
           [0029]      FIG. 6  is a partial schematic side view of a mechanism for capacitively sensing mouse motion; 
           [0030]      FIG. 7  is a partial schematic side view of a capacitance detector and capacitance measurement circuit for use herein; 
           [0031]      FIGS. 8A and 8B  are side views of typical capacitive switches housed within a mouse enclosure; 
           [0032]      FIG. 9  is a partial schematic side view of a scrolling wheel, capacitive rotary encoder and processor for use herein; 
           [0033]      FIG. 10  is a partial schematic view of a further version of a capacitive scrolling control for use in the present invention; 
           [0034]      FIGS. 11A through 11D  are side and top plan views, respectively, of a mouse enclosure showing plates for capacitive sensing; 
           [0035]      FIGS. 12A through 12E  are side views of sensors mounted for use herein; 
           [0036]      FIGS. 13A through 13D  are schematic views of alternative patterns for sensors for use herein; 
           [0037]      FIG. 14  is a top plan view of a mouse enclosure and scrolling area for use in creating the present capacitive mouse; 
           [0038]      FIG. 15  is a graphical depiction showing total summed capacitance signal over time in employing the capacitive mouse of the present invention; 
           [0039]      FIGS. 16A through 16C  are graphical depictions of the coasting feature of the present invention; 
           [0040]      FIG. 17  is a side view of a mouse enclosure housing the capacitive features of the present invention; and 
           [0041]      FIG. 18  is a schematic view of a scrolling module for use as a component of the present capacitive mouse. 
       
    
    
     DETAILED DESCRIPTION 
       [0042]    The following description of preferred embodiments of the disclosure is not intended to limit the scope of the invention to these preferred embodiments, but rather to enable any person skilled in the art to make and use the invention. 
         [0043]    For reference,  FIG. 1A  shows the elements of a conventional prior art mouse  100  in side view. Enclosure  102 , typically of hard plastic, forms the body of the mouse. Ball  104  protrudes from the bottom of enclosure  102  through a small hole. Motion of the mouse over a flat surface causes ball  104  to rotate; this rotation is measured by rotary encoders  106 . Typically two rotary encoders are used to measure motion of the mouse in two orthogonal axes. Buttons  108  form part of the top surface of enclosure  102 . Finger pressure on buttons  108  is detected by switches  110  mounted below the buttons. Scroll wheel  112  is mounted between buttons  108 ; its rotation is measured by rotary encoder  114 . Inputs from rotary encoders  106  and  114  and switches  110  are combined by processor  116  and transmitted to a host computer via cable  118 . 
         [0044]      FIG. 1B  shows the same mouse  100  in top view, featuring enclosure  102 , ball  104 , buttons  108 , scroll wheel  112 , and cable  118 . 
         [0045]      FIG. 2A  shows a typical prior art rotary encoder  200 . Rotation of ball  202  causes shaft  204  to spin, thus rotating notched disc  206 . Light emitter  208  passes light beam  214  through the notches of disc  206  to light detector  210 . As disc  214  spins, the pattern of signals from detector  210  allows processor  212  to deduce the direction and speed of rotation. Note that shaft  204  is excited only by rotation of ball  202  about an axis parallel to shaft  204 . By mounting a second rotary decoder (not shown) perpendicular to rotary decoder  200 , rotation of ball  202  about two axes, and hence motion of the mouse in a two-dimensional plane, can be detected. 
         [0046]      FIG. 2B  shows a detail view of notched disc  206  and light detector  210 . Detector  210  actually contains two light sensitive elements  220  and  222  spaced closely together relative to the spacing of notches  224 . As disc  206  rotates in the direction indicated by arrow  226 , light sensitive elements  220  and  222  are first both exposed to light through notch  224 , then element  220  is eclipsed by the body of disc  206 , then element  222  is also eclipsed, then element  220  is exposed to light through adjacent notch  228 , then element  222  is also exposed to light through notch  228 . Sensors  220  and  222  thus generate the digital quadrature waveform shown in  FIG. 2C  over time. If disc  206  rotates in the direction opposite arrow  226 , the sensors are eclipsed in the opposite order and they generate the digital waveform shown in  FIG. 2D . By digitally reading the outputs of light sensors  220  and  222  and decoding the quadrature signals therein, the processor can determine the direction and amount of motion of disc  206 . 
         [0047]    In an alternate embodiment, light sensitive elements  220  and  222  can be separated and placed at analogous positions within two distinct notch positions of disc  206 . This embodiment is preferable if the light sensors  220  and  222  are too large to be placed closely together; the disadvantage is that it is more difficult to align sensors  220  and  222  precisely relative to one another. 
         [0048]      FIG. 3A  shows a rotary encoder  300  that operates on capacitive instead of optical principles. Ball  302  spins shaft  304  and notched disc  306 . Shaft  304  and disc  306  are made of a conductive material such as metal, and the assembly consisting of shaft  304  and disc  306  is electrically grounded by grounding element  308 . Capacitance detector  310  measures the capacitive effects of grounded disc  306 . Various methods for grounding a spinning object, such as metal brushings, are known in the art. Alternatively, only disc  306  can be made conductive, with ground  308  applied directly to disc  306 . In yet another alternative embodiment, disc  306  is capacitively coupled to a nearby grounded object. In yet another embodiment, a transcapacitance measurement may be done between the body of disc  306  and detector  310 , possibly by driving a time-varying signal into disc  306  and measuring the amplitude of coupling of that signal onto detector  310 . In any case, capacitance detector  310  measures the position of disc  306  by its capacitive effects, and the resulting signals are read by processor  312 . 
         [0049]      FIG. 3B  shows a detail view of notched disc  306  and capacitance detector  310 . As in the case of the optical detector of  FIG. 2B , capacitance detector  310  is formed of two conductive plates  320  and  322  placed near but not touching the plane of disc  306 . When notch  324  of disc  306  is situated adjacent to plates  320  and  322 , those plates each have a low capacitance to ground. As the body of disc  306  moves to be adjacent to plate  320  and then to plate  322 , the capacitance to ground of these plates rises to a higher level. Because capacitance is linearly related to the area of overlap of conductive plates, this rise of capacitance of plate  320  is linear. As disc  306  completely covers plate  320  and begins to cover plate  322 , the capacitance of plate  320  stays relatively constant while the capacitance of plate  322  linearly rises. As disc  306  continues to rotate in the direction of arrow  326 , the capacitance of plate  320  and then plate  322  falls linearly, as depicted in the waveforms of  FIG. 3C . If disc  306  rotates in a direction opposite arrow  326 , the capacitances of plates  320  and  322  instead generate the waveform of  FIG. 3D . 
         [0050]    Those experienced in the art will recognize that plates  320  and  322  may be actual metal plates, or they may equivalently be conductive regions formed in a variety of ways, including but not limited to conductive ink painted or screened on a surface or substrate, conductive material such as metal or indium tin oxide plated or otherwise disposed on a surface or substrate, or any other conductive object with at least one substantially flat portion placed in close proximity to disc  306 . Similarly, the conductive notched disc  306  may be an actual notched metal disc, or it may be a notched conductive pattern formed on a disc-shaped substrate. The dielectric component of the capacitance between plates  320  and  322  and disc  306  may be an empty gap, a coating, surface, substrate, or other intermediary object, or some combination thereof whose thickness and dielectric constant yield a conveniently measurable capacitance. 
         [0051]    Those experienced in the art will further recognize that rotary capacitive sensors are not limited to the disc configuration. Any arrangement in which an irregular conductive object rotates near a conductive sensor will work equally well. In one alternate embodiment, disc  306  is extruded to form a rotating drum with a notched or patterned conductive surface, and plates  320  and  322  are oriented along the long dimension of the drum. The drum embodiment is bulky and mechanically more complex, but allows a larger area of capacitive overlap and hence a stronger capacitance signal. In another alternate embodiment, the notched disc could be simplified to a single “notch,” resulting in a semicircular conductive cam facing quarter-circle plates  320  and  322 . 
         [0052]    One way to process the capacitance signals from plates  320  and  322  is to compare them against fixed capacitance thresholds. Referring to  FIGS. 3D and 3E , comparing capacitance  340  against threshold  344  yields digital waveform  348 ; similarly, comparing capacitance  342  against threshold  346  yields digital waveform  350 . Note that waveforms  348  and  350  of  FIG. 3E  are identical in nature to the digital waveforms of  FIG. 2D . Hence, if threshold comparison is used in this manner to generate digital waveforms, these digital waveforms can be processed by a processor  312  identical to processor  212  of the conventional optical rotary encoder of  FIG. 2B . 
         [0053]    Capacitance detector  310  can use any of a number of methods for measuring capacitance as are known in the art. U.S. Pat. No. 5,880,411 discloses one such capacitance measuring circuit. 
         [0054]    As in the case of the optical encoder of  FIG. 2A , note that plates  320  and  322  may be placed adjacent to different notches as long as their positioning within their respective notches is maintained. However, since plates  320  and  322  do not require housings or packages outside the plates themselves, it is convenient to place them side by side mounted on a common substrate in order to ensure that they will remain aligned to each other. 
         [0055]    One skilled in the art will observe that by examining the original analog capacitance waveforms of  FIGS. 3C and 3D , it is possible to locate disc  306  to a much finer resolution than the notch spacing. This is because at any given point in time, one of the capacitance signals is varying linearly with disc rotation while the other is constant. By tracking these linear variations, processor  312  can track disc rotation at a resolution limited only by the resolution and linearity of the capacitance measurements. In the preferred embodiment, the circuits disclosed in U.S. Pat. No. 5,880,411 are used to perform these precise capacitance measurements. 
         [0056]    Because disc rotation can be measured to much higher resolution than the notch spacing, it is possible to use much larger notches on disc  306 , and correspondingly larger plates  320  and  322 , than are feasible for the analogous notches and sensors of the optical encoder of  FIG. 2A . Larger notches and plates allow mechanical tolerances of the assembly to be relaxed, yielding potentially lower costs. Even with larger notches and plates, a capacitive rotary encoder can produce higher-resolution data than an optical rotary encoder if a sufficiently high-resolution capacitance detector is used. Larger plates  320  and  322  also result in a larger capacitance signal which is easier for detector  310  to measure. 
         [0057]    The plates  320  and  322  and grounding mechanism  308 , being simple formed metal pieces or plated conductive patterns, may also be less costly than the semiconductor light emitters and sensors of  FIG. 2A . 
         [0058]    Another advantage of the capacitive rotary encoder is that it is not affected by optically opaque foreign matter, such as dirt, which may be picked up and introduced into the assembly by ball  306 . The looser mechanical tolerances allowed by the capacitive rotary encoder may also make it more resistant to jamming by foreign matter. 
         [0059]      FIG. 4  shows a side view of the capacitive rotary encoder, with disc  400  and plates  402  and  404  separate by a gap  406 . Gap  406  is drawn large for illustrative purposes, but in the preferred embodiment gap  406  is kept as small as possible to maximize the capacitance between disc  400  and plates  402  and  404 . If gap  406  is small, and the tolerances of the encoder assembly are loose as previously disclosed, then movement of disc  400  along the axis of shaft  408  will have a proportionately large effect on the width of gap  406 . This variation can impact the accuracy of the capacitance measurements of plates  402  and  404 .  FIG. 5  shows an enhancement to the arrangement of  FIG. 3A  that solves this problem. 
         [0060]    In  FIG. 5 , disc  500  is adjacent to three plates  502 ,  504 , and  506 . Plates  502  and  504  are identical to plates  320  and  322  of  FIG. 3A . Plate  506  is the size of plates  502  and  504  combined, and is located near plates  502  and  504 ; in  FIG. 5 , plate  506  occupies the next notch space after plates  502  and  504 . In an alternative embodiment, matching could be improved by splitting plate  506  into two half-plates each exactly the size of plates  502  and  504 . In the system of  FIG. 5 , the processor computes the sum of the capacitance measurements from plates  502 ,  504 , and  506 . Note that the total overlap area between disc  500  and plates  502 ,  504 , and  506  is constant regardless of the rotary position of disc  500 . Hence, the summed capacitance of plates  502 ,  504 , and  506  should be constant. Variation in this sum indicates that disc  500  has shifted relative to plates  502 ,  504 , and  506 , for example, by moving along the axis as shown in  FIG. 4 . The processor divides each plate capacitance measurement by the summed capacitance in order to normalize the capacitance measurements. These normalized measurements are invariant of the width of gap  406  of  FIG. 4 , and are suitable for use in the position computations previously discussed. 
         [0061]      FIG. 6  shows an alternative mechanism for capacitively sensing mouse motion. This mechanism employs a rolling ball  602  protruding from a hole in enclosure  600  similar to that of a conventional mouse. The surface of ball  602  is patterned with regions  604  of higher and lower conductivity. This patterning can be accomplished by forming the ball of material such as rubber of varying conductivity, or by treating the surface of the ball with conductive substances such as paint or metal. The conductive surface of the ball may be protected if necessary by a dielectric outer layer  606 . Capacitance detectors  608  are placed in several locations proximate to ball  602 . As the ball rolls, the conductive regions  604  will move from one capacitance detector to another; processor  610  correlates these signals to measure the movement of ball  602 . Because the capacitance measurements vary linearly as conductive region  604  moves from one detector  608  to another, processor  610  can interpolate in order to measure movement of the ball to very high resolution. 
         [0062]    The system of  FIG. 6  requires several sensors  608  in order to ensure that at least one conductive region  604  is detectable at all times. Conductive regions  604  should be as large as possible in order to maximize the capacitive signal, subject to the constraint that different regions  604  should be separated by enough distance to allow individual regions  604  and the spaces between them to be resolved by detectors  608 . Hence, the spaces between regions  604  should be at least comparable to the size of detectors  608 , and the conductive regions  604  should be at least a significant fraction of the size of detectors  608 . 
         [0063]      FIG. 6  depicts a linear row of sensors  608  curved around the surface of ball  602 . Such an arrangement can detect rolling of the ball in one dimension; the example of  FIG. 6  would detect the rolling resulting from motion of the mouse along axis  612 . In the preferred embodiment, other sensors (not shown) are arranged in a row perpendicular to the row of sensors  608  in order to measure motion of the mouse in two dimensions. 
         [0064]    In one embodiment, the conductive regions in the ball are grounded to facilitate capacitance measurements by simple conductive plates. However, grounding the conductive regions of the ball may be impractical, so in the preferred embodiment, capacitance detectors  608  measure transcapacitance. 
         [0065]      FIG. 7  shows one simple way to measure transcapacitance. The capacitance detector  700  consists of two plates  702  and  704 . Plate  702  is connected to ground, and plate  704  is connected to a capacitance measurement circuit  706 . Proximity to an electrically floating conductor  708  within ball  710  creates a capacitive coupling  712  from plate  702  to conductor  708 , and a capacitive coupling  714  from conductor  708  to plate  704 , hence effectively coupling plate  702  to plate  704  through two series capacitances. Those experienced in the art will recognize that many other configurations of plates  702  and  704  are possible, such as interdigitated lines or concentric circles and toroidal shapes. In still another embodiment of capacitance detector  700 , plate  702  could be driven with a time-varying signal which is capacitively coupled onto plate  704  and detected by circuit  706 . 
         [0066]    The motion sensor of  FIG. 6  requires even fewer moving parts than that of  FIG. 3 , and thus can lead to an even cheaper and more physically robust mouse. However, the system of  FIG. 6  has the disadvantage of requiring more complex processing in processor  610 . 
         [0067]    Other methods for detecting mouse motion are known in the art, such as the optical methods of U.S. Pat. No. 4,546,347 (Kirsch) and U.S. Pat. No. 5,907,152 (Dandiker et al.). Fully solid-state optical motion detectors would pair well with the capacitive button and scrolling controls of the present invention to form an entirely solid-state optical/capacitive mouse. 
         [0068]    Mice conventionally include one or more buttons as well as a motion detector. Referring back to  FIG. 1 , button  108  is typically linked to a mechanical switch  110 . By pressing down on the surface of switch  108 , the user closes switch  110 . Mechanical switches have various well known disadvantages. Since they have moving parts, mechanical switches can fail over time or with rough handling. Also, mechanical switches require a certain threshold of pressure for activation, which can tire the user with repeated use. 
         [0069]    Mechanical switches can be replaced by capacitive sensors in several ways.  FIG. 8A  shows one type of capacitive switch that is well-known in the art. Enclosure  800 , for example a mouse enclosure, may be shaped similarly to that of a conventional mouse, but with no moving parts in its top surface. Conductive plate  802  is placed on or near the surface of the enclosure, preferably covered by a protective dielectric layer  806 . In an embodiment, capacitance measurement circuit  804  monitors the capacitance of plate  802 . When a finger (not shown) touches surface region  806 , the capacitance to ground of plate  802  increases beyond a threshold set by measurement circuit  804 . When no finger is present, the capacitance to ground of plate  802  is below the threshold. By comparing the capacitance of plate  802  to the threshold, circuit  804  can generate a digital signal which is equivalent to the signal produced by a mechanical switch. 
         [0070]    The system of  FIG. 8A  implements a mouse button which requires zero activation force; indeed, depending on the threshold setting, it could even be sensitive to mere proximity of the finger. Although this mouse button solves the problem of tiring the finger during repeated activations, it introduces the converse problem of tiring the finger during periods of inactivity, since the finger must not be rested against surface  806  without accidentally activating the button. 
         [0071]      FIG. 8B  shows a second type of capacitive switch, also well-known in the art. Enclosure  820  includes a separate movable button portion  822  as in a conventional mouse. Instead of a mechanical switch beneath button  822 , there is a conductive plate  826  and some sort of spring mechanism  824 . A variety of mechanisms  824  are usable and well-known, including but not limited to metal springs, compressible foam, or single-piece enclosures with buttons made of springy material. Spring mechanism  824  may optionally also include a tactile feedback means to impart the familiar clicking feel to button activations. A second conductive plate  828  is mounted beneath plate  826  so that pressure on button  822  brings plate  826  measurably closer to plate  828 , thus increasing the capacitance between plates  826  and  828 . Capacitance measuring circuit  830  detects this change in capacitance to form a button signal. 
         [0072]    Because the system of  FIG. 8B  works by measuring the capacitance between plates  826  and  828 , these plates do not need to make electrical contact in order to activate the button. Indeed, these plates must be kept out of electrical contact in order for capacitance measuring circuit  830  to operate properly. Many straightforward ways are known to separate plates  826  and  828 , including but not limited to an insulating surface on plate  826 , plate  828 , or both plates, or an insulating compressible foam placed between the plates. 
         [0073]    The system of  FIG. 8B  is very similar to a conventional mechanical switch, but it is more resistant to dirt and wear because button activation does not require an electrical contact to be made. 
         [0074]    Capacitance measuring circuits  804  and  830  may use any of a variety of well-known capacitance measuring techniques. In the preferred embodiment, a circuit like that disclosed in U.S. Pat. No. 5,880,411 is used. 
         [0075]    Many mice also include a scrolling mechanism. This mechanism typically employs a rotating wheel, an isometric joystick, or a set of directionally arranged buttons; the scrolling mechanism  112  is typically mounted between two mouse buttons  108  as shown in  FIG. 1B . 
         [0076]      FIG. 9  shows one way to measure a scrolling command capacitively. A scrolling wheel  902  is mounted in mouse enclosure  900 , seen in side view. The wheel appears to the user to be the same as the wheel of the conventional mouse of  FIG. 1A and 1B . Rotation of the wheel is measured by capacitive rotary encoder  904  and processor  906  similar to those of  FIG. 3A and 3B . The capacitive rotary encoder  904  can be mounted directly on the axis of scrolling wheel  902  as shown in  FIG. 9 , or wheel  902  can be mechanically linked to a separate rotary encoder mechanism elsewhere in enclosure  900 . 
         [0077]      FIG. 10  shows another capacitive scrolling control. A scrolling knob  1002  protrudes from mouse enclosure  1000 . Knob  1002  is connected by stick  1004  to conductive plate  1006  and to spring mechanism  1008 . Depending on the stiffness of spring  1008 , knob  1002  may act as either a rocking control or an isometric joystick. Conductive plates  1010  and  1012  are mounted near plate  1006 , and capacitance measuring circuit  1014  measures the capacitances between plate  1010  and plate  1006 , and between plate  1012  and plate  1006 . When knob  1002  is pressed in a forward or backward direction, plate  1006  is deflected slightly to produce a measurable change in the capacitances of plates  1010  and  1012 . By comparing the capacitances of plates  1010  and  1012 , circuit  1014  can detect this forward or backward deflection to produce a scrolling command. Also, by noting an increase in capacitance of both plates  1010  and  1012  at once, circuit  1014  can detect downward pressure exerted on knob  1002 . Many conventional mice use a downward deflection of the scrolling control as an additional command signal, such as the activation of a third mouse button. 
         [0078]    By placing two additional plates along an axis perpendicular to the axis of plates  1010  and  1012 , it is possible to measure deflection of knob  1012  in three dimensions. Sideways deflection of knob  1012  can be interpreted as a command for horizontal scrolling, or panning Forward and backward deflection can be interpreted as vertical scrolling, and downward deflection can be interpreted as an additional mouse button or other special command. 
         [0079]    In an alternate embodiment, plates  1010  and  1012  are situated above plate  1006  so that pressure on knob  1002  causes plate  1006  to deflect away from plates  1010  and  1012 , and the measured capacitance on plates  1010  and  1012  to decrease with pressure instead of increasing. Those skilled in the art will recognize that the processing necessary for this embodiment is identical to that required for the embodiment of  FIG. 10  except for a change of sign. 
         [0080]    The systems of  FIGS. 9 and 10  share the disadvantage that they are still mechanical devices with moving parts. For greatest robustness and sensitivity and lowest cost, a truly solid state solution to scrolling is preferable. 
         [0081]      FIG. 11A  shows a scrolling control that operates directly on capacitive sensing principles. Mouse enclosure  1100  contains an array of conductive plates  1102  connected to a processor  1104  that includes capacitance measuring circuits. Plates  1102  are insulated from the user&#39;s finger by surface  1106 . In the preferred embodiment, the array of plates  1102  is placed in between two mouse buttons  1108  as shown in  FIG. 11B . Many alternate embodiments in which the scrolling control is placed elsewhere are possible, such as the embodiment of  FIG. 11  C in which the scrolling control is mounted on the side of mouse enclosure  1100  for access by the user&#39;s thumb. The mouse buttons  1108  of  FIGS. 11B and 11C  could be capacitive buttons as previously disclosed, or conventional mechanical switches or any other suitable type of button. 
         [0082]      FIG. 11D  shows yet another configuration, in which scrolling sensors  1102  are placed on top of a conventional mouse button  1108 ; pressing down on button  1108  without substantially moving the finger produces a button click, while lightly touching button  1108  and then moving the finger generates scrolling. 
         [0083]    Preferably, plates  1102  are numerous and spaced closely together so as to allow interpolation of the finger position to greater resolution than the plate spacing. In one preferred embodiment, nine plates are used spanning a distance of approximately one inch. U.S. Pat. No. 5,880, 411 discloses a preferred method for measuring the capacitances of an array of sensors and interpolating the finger position from those measured capacitances. Many other methods are possible and well-known in the art, such as that of U.S. Pat. No. 5,305,017 to Gerpheide. 
         [0084]    Once the finger position among plates  1102  is known, motion of the finger along the axis of plates  1002  can be measured by comparing finger positions at successive times. Processor  1104  generates a scrolling signal of a certain direction and distance when a finger motion of a corresponding direction and distance is measured. The effect as observed by the user is as if the user were rolling a wheel like wheel  902  of  FIG. 9  by moving the finger forward and backward on the top edge of the wheel. Instead, the user moves the finger forward and backward along sensor surface  1106  to produce the identical scrolling signals. 
         [0085]    In any scrolling mouse, but particularly in a capacitive scrolling mouse, it may be desirable to provide for different regimes of low-speed and high-speed scrolling in order to account for the fact that the scroll surface  1106  is much shorter than a typical scroll bar in a typical graphical user interface. A simple way to provide for different speed regimes is to use the technique commonly known as “acceleration” or “ballistics” when applied to mouse motion signals. In this technique, very small finger motions translate to disproportionately small scroll signals, and very large finger motions translate to disproportionately large scroll signals. 
         [0086]    In the preferred embodiment, processor  1104  measures the total amount of finger signal as well as the finger position, and generates a scrolling signal only when sufficient finger signal is present. Otherwise, the scrolling signal when no finger was present would be ill-defined, and the mouse would be prone to undesirable accidental scrolling. In the preferred embodiment, processor  1104  compares the total summed capacitance on all sensors  1102  against a threshold to determine finger presence or absence; in an alternate embodiment, processor  1104  instead compares the largest capacitance signal among all sensors  1102  against a threshold. The threshold should be set high enough so that only deliberate finger actions result in scrolling. If the threshold is set too low, the mouse may scroll in response to mere proximity of the finger, in general an undesirable feature. 
         [0087]    There are many ways to mount sensors  1102  under surface  1106  or to otherwise integrate the sensors into enclosure  1100 . Some of these ways are depicted in  FIGS. 12A through 12E . Those experienced in the art will realize that many other mounting schemes are possible, and that the particular choice of mounting scheme does not alter the essence or the basic operation of the invention. 
         [0088]    In  FIG. 12A , scrolling surface  1202  is an uninterrupted region of the top layer  1201  of enclosure  1200 . In the embodiment illustrated in  FIG. 12 , top layer  1201  includes an external surface (front surface)  1207  and an internal surface (back or underside surface)  1203 . Sensors  1204  are affixed to the internal surface  1203  of enclosure  1200 , for example using adhesive or other intermediary substance  1206 . Adhesive  1206  could be eliminated by the use of a self-adhesive sensor material  1204  such as conductive paint. Wires or other conductors  1205  connect sensors  1204  to processor  1208 . 
         [0089]    In  FIG. 12B , sensors  1204  are disposed on a substrate material  1206  which is then affixed to the internal surface  1203  of enclosure  1200 . Sensors  1204  might be composed of conductive ink, indium tin oxide, metal foil, or any other conductive material. Substrate  1206  might be polyester film, plastic, glass, or any other flexible or bendable material on which conductive sensors can be disposed. In the example of  FIG. 12B , substrate  1206  is shown extending downwardly (e.g., through bending) and away from enclosure  1200  to carry the conductive signals from sensors  1204  to processor  1208 . 
         [0090]    In  FIG. 12C , the material which forms the top layer  1201  of enclosure  1200  in or near scrolling region  1202  has been made thinner than normal in order to reduce the distance between, and thereby increase the capacitive coupling between, sensors  1204  and the finger. Additionally, sensors  1204  have been disposed on the opposite side of substrate  1206  (as compared to the embodiments shown in  FIGS. 12A and 12B ) in order to increase the proximity of the sensors to the finger. To strengthen the top layer  1201  of the enclosure, solid backing plate  1210  can optionally be placed behind the sensors  1204 . Layer  1210  may also be made conductive and electrically grounded in order to isolate sensors  1204  from interference from other circuits within the mouse. A similar grounded shield may be used in any of the other sensor arrangements disclosed herein. 
         [0091]    In  FIG. 12D , substrate  1206  extends from the inside of enclosure  1200 , with an intermediate portion of substrate  1206  extending out through hole  1212  to the external surface (outside surface) of enclosure  1200 . In this example, substrate  1206  itself forms the protective dielectric layer associated with the scrolling surface  1202  between sensors  1204  and the finger. Hole  1212  may be protected and disguised in various ways, such as by combining hole  1212  with the opening around the edge of a mechanical mouse button. 
         [0092]    In  FIG. 12E , sensors  1204  are embedded directly into the material of enclosure  1200 , for example in the form of wires or foil strips encased in plastic. 
         [0093]    When sensors  1204  are disposed on a substrate  1206 , it is convenient to use an extension of substrate  1206  to carry the sensor signals to processor  1208 , as shown in  FIGS. 12B ,  12 C, and  12 D. In these cases, sensors  1204  and their associated wiring may be patterned on substrate  1206  using conductive ink or other suitable material.  FIGS. 13A to 13D  show several of the many possible patterns. 
         [0094]    In  FIG. 13A , substrate  1300  extends beyond the area of sensors  1302  on one side (e.g., to the right). This side extension  1306  forms a carrier for the sensor signals carried by the wires or conductors  1304  to a processor  1308 . Processor  1308  may be mounted to the side of sensor area  1302  as shown, or it may be mounted beneath sensor  1302  or in another location, with a bendable extension  1306  bending, folding or warping as it leads away from sensor  1302 . 
         [0095]    In  FIG. 13B , wires  1304  are shown as being bent at  90  degrees and extension  1306  leads away along the length of the area of sensors  1302 . 
         [0096]      FIG. 13C  is similar to  FIG. 13B , but sensors  1304  leave the area of sensors  1302  on both sides in order to balance the extension of substrate  1300  to the sides of the area of sensors  1302 . 
         [0097]    In  FIG. 13D , two layers of conductive material are used with an insulating layer or substrate therebetween. The first conductive layer contains sensors  1302 . The second conductive layer contains conductors  1304  which carry the sensor signals and which extend in a direction perpendicular to sensors  1302 . Vias  1310  penetrate the insulating layer or substrate to connect sensors  1302  to signal wires  1304 . In crossings  1312  of wires  1304  over sensors  1302  without vias, the two conductive layers are electrically isolated although there may be some capacitive coupling that processor  1308  may take into account. The sensor design of  FIG. 13D  may be more expensive due to its use of additional layers, but it avoids excess extension of substrate  1300  around the area of sensors  1302 . Such extension may be undesirable for design or aesthetic reasons, in addition to providing opportunities for undesirable capacitive coupling between the finger and wires  1304  when the finger touches near but not directly in the area of sensors  1302 . The latter undesirable capacitive coupling can also be remedied by the addition of a grounded shield over the exposed wires  1304 , as shown by region  1314  of  FIG. 13B . 
         [0098]    Yet another embodiment of the capacitive scrolling control is shown in  FIG. 14 . Mouse enclosure  1400  includes a two-dimensional scrolling area  1402  preferably disposed between mouse buttons  1408 . Scrolling area  1402  includes first plurality of sensors  1404  disposed in one direction, and a second overlapping plurality of sensors  1406  disposed in a substantially perpendicular direction to form a two-dimensional matrix. Each plurality of sensors is processed using methods analogous to  FIGS. 11 through 13 ; the position results from the two pluralities are combined to form the complete finger location in two dimensions. 
         [0099]    Two-dimensional capacitive touch sensors, or touch pads, are well known in the art. In the preferred embodiment, the methods of U.S. Pat. No. 5,880, 411 are used.  FIG. 2  of the &#39;411 patent illustrates a diamond pattern for sensor matrix  1402  which is preferred due to various advantages disclosed in that patent. Many other sensing techniques and sensor geometries are known in the art. 
         [0100]    Once the finger position in two dimensions is known, finger motion in the horizontal and vertical directions can be measured by comparing finger positions at successive times. Horizontal finger motion translates to horizontal scrolling, or panning Vertical finger motion translates to vertical scrolling. In one embodiment, diagonal finger motion translates to simultaneous horizontal and vertical scrolling. In an alternate embodiment, the horizontal and vertical motion signals are compared to discover whether the finger motion is primarily horizontal or primarily vertical, and the corresponding type of scrolling is applied. 
         [0101]    Scrolling wheel mice like that of U.S. Pat. No. 5,530,455 typically contain an additional switch to sense when the wheel is pressed down by the user. This switch generates a signal similar to a third mouse button signal for enabling additional scrolling or other features in host software. A comparable switch could be mounted beneath the capacitive touch sensors of  FIGS. 11 through 14 , but other methods are preferred in order to avoid the cost and reliability problems inherent in switches. 
         [0102]    One way to simulate a third mouse button in a capacitive scrolling control is to decode tapping gestures using the various methods disclosed in U.S. Pat. No. 5,880,411. In the most simple case, basic finger taps are decoded and translated into simulated clicks of the third mouse button.  FIG. 15  shows the total summed capacitance signal over time, and the corresponding third button signal resulting from tap detection. The &#39;411 patent discloses many additional refinements for tap detection on capacitive touch sensors, many of which are suitable for application to scrolling controls. 
         [0103]    A second way to simulate a third mouse button is to introduce an additional touch sensor plate which forms a capacitive button as disclosed in  FIGS. 8A  or  8 B. 
         [0104]    Arrayed capacitive touch sensors, particularly two-dimensional sensors like that of  FIG. 14 , can resolve numerous additional types of input that more specialized sensors like wheels and isometric joysticks cannot. One example is the use of multiple fingers to activate special modes or user interface commands; U.S. Pat. No. 5,880,441 discloses one embodiment of multi-finger sensing. Another example is graphic gestures, where looping motions and other finger motions that are not entirely horizontal or vertical can be interpreted as special user interface commands. Yet another example is special designated zones in which finger motion or tapping invokes special behaviors. 
         [0105]    Because the capacitive scrolling control feels similar to a scrolling wheel to the user, other techniques may be employed to strengthen the wheel analogy. One such technique is “momentum” or “coasting,” in which scrolling behavior is adjusted based on the velocity of finger motion as the finger lifts away from the scroll sensor; that is, the scrolling speed may be determined based on the instantaneous velocity of the finger at the point the finger lifts from the scroll surface. 
         [0106]      FIGS. 16A and 16B  illustrate the basic coasting feature. Each figure shows the finger presence or absence, the computed finger motion, and the resulting scrolling signal generated by the mouse. For simplicity, motion and scrolling in only one dimension are considered as in the case of  FIG. 11 ; the two-dimensional scrolling of  FIG. 14  leads to a straightforward generalization of  FIG. 16 . Note that the finger motion is undefined when the finger is absent; in  FIGS. 16A and 16B , the motion is plotted as zero when the finger is absent for purposes of illustration. 
         [0107]    In  FIG. 16A , the finger touches the scrolling sensor, moves back and forth to generate a corresponding back-and-forth scrolling signal, then comes to a complete stop before lifting. When the processor observes a zero or near-zero velocity as the finger lifts, i.e., when the finger is stationary immediately prior to lifting, the processor ceases all scrolling activity; coasting does not occur. 
         [0108]    In  FIG. 16B , the finger executes the same scrolling motions, but then moves again and lifts while still moving. When the processor observes that the velocity was substantially non-zero as the finger began lifting, the processor continues scrolling in a direction and speed determined by the final velocity of the finger upon lifting. The effect as seen by the user is that the imaginary scroll wheel is left spinning, or coasting—much like a roulette wheel continues to rotate after manually spinning it. In the preferred embodiment, the coasting speed and direction are equal to the scrolling speed and direction just before the finger lifted, though in alternate embodiments, the coasting speed could be constant or the coasting speed and direction could be some other function of the final scrolling speed and direction. 
         [0109]    To terminate coasting, the user simply returns the finger to the scrolling control as seen in  FIG. 16B . No special processing is needed to accomplish this aspect of coasting: As soon as the finger returns to the scrolling control, the coasting signal is replaced by fresh motion signals, which are zero until the finger actually moves on the control. The effect as seen by the user is that the imaginary spinning scroll wheel is halted as soon as the finger is pressed on it. Coasting is a valuable aid to long-distance scrolling through large documents. 
         [0110]      FIG. 16C  shows an additional embodiment or implementation of the coasting feature, wherein friction is simulated thereby having the coasting speed slowly decay to zero. Much like a spinning roulette wheel loses its momentum and slows down to a stop.  FIG. 16C  shows an alternate scrolling signal to that of  FIG. 16B  in which friction slows the coasting effect over time. 
         [0111]    The user can still halt the coasting before it has come to a natural stop by touching the finger back to the scrolling control. 
         [0112]    Some mice offer other features in addition to motion, two buttons, and scrolling. Many of these features are also well suited to a capacitive implementation. One example is additional buttons for special functions such as Internet browsing. Another example is additional scroll-like functions such as a separate “zoom” control. Still another example is a general hand proximity sensor on the mouse enclosure that allows the mouse and associated software to tell whether or not the user&#39;s hand is gripping the mouse. Those experienced in the art will recognize that the various types of capacitive sensors, buttons, rotary, linear and two-dimensional, are appropriate for a wide variety of applications beyond those specific examples disclosed here. 
         [0113]    Referring back to  FIG. 1 , any combination of one or more of the motion sensors  106 , button sensors  110 , scrolling sensors  114 , and any additional sensors can be implemented by capacitive methods as disclosed herein. In typical mice, the signals from all these types of sensors, whether capacitive, mechanical, optical or otherwise are combined in processor  116  to produce a mouse signal to be sent to the host computer. Standard protocols are well known in the art for sending motion, button, and scrolling signals from a mouse to a host computer. These same protocols may be used when one, several, or all of the sensors are implemented by capacitive techniques. Thus, the capacitive mouse of the present invention is fully interchangeable with conventional mice with no change to host mouse drivers or other system-level facilities. 
         [0114]    It is possible and may be desirable to construct a mouse that uses a combination of capacitive, mechanical and other sensing techniques. For example, a capacitive scrolling sensor could be added to an otherwise conventional mechanical mouse. Or, a capacitive motion sensor could be used on a mouse with mechanical buttons and no scrolling control at all. 
         [0115]    If several or all sensor functions of the mouse are implemented capacitively, it may be possible to use a single capacitive sensing chip for all capacitive sensing functions. Thus, for example, if capacitive sensing is used on the mouse for scrolling, then it may cost little more to implement the motion sensor capacitively as well using additional input channels of the same capacitance measuring chip. 
         [0116]    It is possible to purchase mouse processor chips that perform all of the tasks of processor  116  or a conventional mouse. These chips generally accept motion and scrolling inputs in quadrature form as shown in  FIGS. 2C and 2D , and the buttons are implemented as switches which alternately drive an input pin to a high or low voltage. 
         [0117]      FIG. 17  shows how a capacitive mouse  1700  can be built using a conventional mouse processor chip  1702  in conjunction with a capacitance measuring chip  1704 . Ball  1706  drives capacitive motion sensor  1708 , whose sensing plates connect to chip  1704 . Scrolling sensors  1710  also connect to chip  1704 , as do the button sensors (not shown). Chip  1704  computes motion and scrolling signals using the techniques disclosed herein, and then generates quadrature signals as outputs with timing and characteristics matching those produced by a true rotary sensor such as that of  FIG. 2A . Chip  1702  then converts these artificial quadrature signals into standard mouse protocols. If quadrature is not appropriate, chips  1704  and  1702  could equally well use any other intermediate form for transmitting motion data. Chip  1704  also measures the signals from the capacitive mouse buttons, and drives its digital output pins high or low based on the observed button capacitances. Chip  1702  reads these digital button signals as if they came from mechanical switches. The arrangement of  FIG. 17  is not as cost-effective as a design with a single chip that does all the tasks, but it may greatly simplify the design of a new mouse using a new protocol or other features not yet supported by standard capacitive sensing chips. 
         [0118]    Yet another alternative is to perform only rudimentary sensor processing on the mouse, producing an intermediate form such as the quadrature output by chip  1704  of  FIG. 17 . These signals can then be sent to a host computer for final processing, thus relieving some of the load from the low-cost mouse hardware. Another variation of this scheme is to send finger position data instead of fully processed scrolling motion data for a capacitive scroll sensor. 
         [0119]      FIG. 18  shows a scrolling module designed to be used as a component in a mouse design. Circuit board  1800  includes an array of sensors  1802  as well as a capacitive sensing chip  1804 . Connector  1806  sends out quadrature signals compatible with conventional rotary encoders. Similarly, a self-contained rotary encoder module could be constructed using capacitive sensors. Using these modules, an industrial designer could construct the mouse of  FIG. 17  using only standard components, without requiring any expertise in capacitive sensing. 
         [0120]    As any person skilled in the art will recognize from the previous description and from the figures and claims, modifications and changes can be made to the preferred embodiments of the invention without departing from the scope of the invention defined in the following claims.