Force-based input device

Disclosed is an input device comprising (a) a base support, having a periphery and a plurality of apertures formed therein to define a circumscribed or circumscribing input pad configured to displace under the applied force; (b) a plurality of isolated beam segments, defined by the plurality of apertures, and operable to receive resultant forces distributed to the isolated beam segments by the displacement of the input pad; (c) at least two sensors, disposed along each isolated beam segment, and configured to measure the forces transmitted from the input pad to the periphery and to output a signal corresponding to the applied force. One or more processing means operable with the plurality of sensors may be utilized to receive the signal and to determine at least one of a location and/or magnitude of the applied force acting on the input pad.

FIELD OF INVENTION

The present invention relates generally to input devices, and more particularly to force-based input devices configured with isolated beam segments designed to concentrate the applied force across the beam segments, wherein the force is measured and processed to obtain or derive specific characteristics about or related to the applied force, such as its location and magnitude as it relates to the input device.

BACKGROUND OF THE INVENTION AND RELATED ART

Input devices (e.g., a touch screen or touch pad) are designed to detect the application of an object and to determine one or more specific characteristics of or relating to the object as relating to the input device, such as the location of the object as acting on the input device, the magnitude of force applied by the object to the input device, etc. Examples of some of the different applications in which input devices may be found include computer display devices, kiosks, games, automatic teller machines, point of sale terminals, vending machines, medical devices, keypads, keyboards, and others.

Currently, there are a variety of different types of input devices available on the market. Some examples include resistive-based input devices, capacitance-based input devices, surface acoustic wave-based devices, force-based input devices, infrared-based devices, and others. While providing some useful functional aspects, each of these prior related types of input devices suffer in one or more areas.

Resistive-based input devices typically comprise two conductive plates that are required to be pressed together until contact is made between them. Resistive sensors only allow transmission of about 75% of the light from the input pad, thereby preventing their application in detailed graphic applications.

Capacitance-based input devices operate by measuring the capacitance of the object applying the force to ground, or by measuring the alteration of the transcapacitance between different sensors. Although inexpensive to manufacture, capacitance-based sensors typically are only capable of detecting large objects as these provide a sufficient capacitance to ground ratio. In other words, capacitance-based sensors typically are only capable of registering or detecting application of an object having suitable conductive properties, thereby eliminating a wide variety of potential useful applications, such as the ability to detect styli and other similar touch or force application objects. In addition, capacitance-based sensors allow transmission of about 90% of input pad light.

Surface acoustic wave-based input devices operate by emitting sound along the surface of the input pad and measuring the interaction of the application of the object with the sound. In addition, surface acoustic wave-based input devices allow transmission of 100% of input pad light, and don't require the applied object to comprise conductive properties. However, surface acoustic wave-based input devices are incapable of registering or detecting the application of hard and small objects, such as pen tips, and they are usually the most expensive of all the types of input devices. In addition, their accuracy and functionality is affected by surface contamination, such as water droplets.

Force-based input devices are configured to measure the location and magnitude of the forces applied to and transmitted by the input pad. Force-based input devices provide some advantages over the other types of input devices. For instance, they are typically very rugged and durable, meaning they are not easily damaged from drops or impact collisions. Indeed, the input pad (e.g., touch screen) can be a thick piece of transparent material, resistant to breakage, scratching and so forth. There are no interposed layers in the input pad that absorb, diffuse or reflect light, thus 100% of available input pad light can be transmitted. They are typically impervious to the accumulation of dirt, dust, oil, moisture or other foreign debris on the input pad. Force-based input devices comprise one or more force sensors that are configured to measure the applied force. The force sensors can be operated with gloved fingers, bare fingers, styli, pens pencils or any object that can apply a force to the input pad. Despite their advantages, force-based input devices are typically too large and bulky to be used effectively in many touch screen applications. Additionally, conventional force-based input devices, as well as most other types of input devices, are capable of registering touch from only one direction, or in other words, on one side of the input pad, thereby limiting the force-based input device to monitor or screen-type applications.

Infrared-based devices are operated by infrared radiation emitted about the surface of the input pad of the device. However, these are sensitive to debris, such as dirt, that affect their accuracy.

SUMMARY OF THE INVENTION

In light of the problems and deficiencies inherent in the prior art, the present invention seeks to overcome these by providing a force-based input device that can determine the location and magnitude of an applied force from either side of the input pad, and that has force sensors that are in, or very near, the plane of the input pad, thereby minimizing the height of the input pad, and also the effect of any forces parallel to the input pad.

In accordance with the invention as embodied and broadly described herein, the present invention features an input device suitable for determining location and magnitude of an applied force, comprising: a) a base support having a periphery and a plurality of apertures formed near the periphery to define an input pad configured to displace under the applied force; b) a plurality of isolated beam segments defined by the plurality of apertures and operable to receive resultant forces distributed to the isolated beam segments by the displacement of the input pad; and c) at least one sensor operable with each isolated beam segment to measure the strain within the respective isolated beam segment occurring as a result of various stresses being created by the displacement of the input pad in response to the applied force and transmitted to the periphery, the at least one sensor also being configured to output a signal corresponding to the applied force and the measured strain to be used to determine a location of the applied force.

Although use of a single sensor may be adequate, as indicated, using two or more sensors provides certain recognized advantages. For example, with two sensors, it may be possible to partially correct temperature effects, as well as to minimize the effects of strains occurring parallel to the sensor plane.

The present invention also features an input device configured to receive an applied force, the input device comprising: a) a first structural element supported in a fixed position; b) a second structural element operable with the first structural element, and dynamically supported to be movable with respect to the first structural element to define an input pad configured to displace under the applied force; c) a plurality of isolated beam segments joining said first and second structural elements, said isolated beam segments being operable to transfer forces between the first and second structural elements, and to receive resultant forces distributed to the isolated beam segments by the displacement of the input pad; and d) at least one sensor operable with each isolated beam segment to measure the strain within the respective isolated beam segment occurring as a result of various stresses transmitted to the isolated beam segments by the displacement of the input pad in response to the applied force, each of the sensors also being configured to output a signal corresponding to the applied force and the measured strain to be used to determine a location of the applied force.

The present invention further features an input device configured to receive an applied force, the input device comprising: a) a base support having a periphery and a plurality of grooves formed at the periphery and extending only partially through the base support, the grooves being configured to define an input pad movable with respect to the base support, the input pad being configured to displace under the applied force; b) a plurality of isolated beam segments defined by the plurality of grooves and operable to receive resultant forces distributed to the isolated beam segments by the displacement of the input pad; and c) at least one sensor operable with each isolated beam segment to measure the strain within the respective isolated beam segment occurring as a result of various stresses being created by the displacement of the input pad in response to the applied force and transmitted to the periphery, the at least one sensor also being configured to output a signal corresponding to the applied force and the measured strain to be used to determine a location of the applied force.

The present invention still further features a method for making a touch pad device, comprising the steps of: a) providing a base support capable of receiving an applied force; b) forming apertures through peripheral locations on the base support to define an input pad and a plurality of isolated beam segments operable to receive resultant forces distributed to the isolated beam segments by the displacement of the input pad; c) providing a plurality of sensors along each of the isolated beam segments to measure the strain within the plurality of isolated beam segments occurring as a result of various stresses created by the displacement of the input pad and transmitted to the peripheral locations in response to the applied force, and to output a signal corresponding to the applied force to be used to determine the location of said applied force.

The present invention still further features a method for determining at least one of location and magnitude of a force applied to an input pad, the method comprising: a) providing a base support having a periphery and a plurality of isolated beam segments formed by a plurality of apertures at the periphery that define an input pad configured to displace in response to the force, the isolated beam segments having located thereon at least one sensor; b) measuring the strain within the plurality of isolated beam segments, which strain occurs as a result of various stresses created by the displacement of the input pad in response to the force as applied thereto; c) generating an output signal from each of the sensors, the output signal corresponding to the measured strain; and d) processing the output signal from the at least two sensors to determine the location of the force applied to the input pad.

The present invention still further features a method for determining at least one of location and magnitude of a force applied to an input pad, the method comprising: a) providing a first structural element; b) providing a second structural element operable with the first structural element to define a plurality of apertures, and dynamically supporting one of said first and second structural elements with respect to the other, which is fixedly supported, to define an input pad configured to displace under the applied force, the plurality of apertures defining a plurality of isolated beam segments operable to transfer forces between the first and second structural elements, and to receive resultant forces distributed to the isolated beam segments by the displacement of the input pad; c) measuring the strain within the plurality of isolated beam segments, which strain occurs as a result of various stresses transmitted to the isolated beam segments by the displacement of the input pad in response to the applied force; d) generating an output signal corresponding to the measured strain; and e) processing the output signal to determine the location of the force applied to the input pad.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following detailed description of exemplary embodiments of the invention makes reference to the accompanying drawings, which form a part hereof and in which are shown, by way of illustration, exemplary embodiments in which the invention may be practiced. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art practice the invention, it should be understood that other embodiments may be realized and that various changes to the invention may be made without departing from the spirit and scope of the present invention. Thus, the following more detailed description of the embodiments of the present invention, as represented inFIGS. 1 through 26, is not intended to limit the scope of the invention, as claimed, but is presented for purposes of illustration only and not limitation to describe the features and characteristics of the present invention, to set forth the best mode of operation of the invention, and to sufficiently enable one skilled in the art to practice the invention. Accordingly, the scope of the present invention is to be defined solely by the appended claims.

The following detailed description and exemplary embodiments of the invention will be best understood by reference to the accompanying drawings, wherein the elements and features of the invention are designated by numerals throughout.

Generally, the present invention describes a force-based input device and methods for making and using the same. The force-based input device is configured to determine the location and the magnitude of a force applied thereto. In some exemplary embodiments, the input device comprises a base support made of a material with suitable elasticity. The base support can be supported on its periphery by any suitable means. The force to be sensed and measured can be applied to an inner portion of the base support referred to herein as an input pad.

The base support may further comprise a plurality of beam segments disposed between the input pad and the periphery of the base support, thus preferably isolating the beam segments from the periphery. The isolated beam segments are configured to control the path of forces that are transmitted from the input pad to the periphery of the base support, and to concentrate the stresses imposed on the input pad by the applied force. The isolated beam segments may be in the form of slots, holes, or other relieved areas formed into the base support.

The force-based input device further comprises one or more sensors configured to be disposed or otherwise located along the isolated beam segments to provide a measure of the force being transmitted from the input pad to the periphery of the base support. The sensors function to measure the strain in the isolated beam segments resulting from stresses in the isolated beam segments caused by the applied force(s), and to provide a corresponding electrical output or signal. The stresses in the isolated beam segments result from the deflection of the input pad in response to application of the applied force(s). The electrical output or signal generated by the sensors can be further processed to derive the location coordinates of the applied force on the input pad, and the magnitude of the applied force. The output signals can also be processed to perform other functions, such as to correcting baseline activity.

In still other embodiments, the sensors may be integral with beam segments, wherein the beam segments comprise piezoelectric or other similar material. In other words, the beam segments themselves may be made of a material capable of functioning as a sensor, thus eliminating the need for separate sensors to be added to the beam segments.

The present invention provides several significant advantages over prior related force-based input devices. First, the force-based input device of the present invention can be very rugged, in that the pad is not easily damaged as a result of drops, impacts, or collisions. Second, the input pad may be configured as a transparent window, an opaque surface, or an integral part of the base support. In addition, the input pad may comprise any suitably elastic material. Third, the sensors can be impervious to accumulation of dirt, dust, oil, moisture or other foreign material on the window. Fourth, the sensors can detect force applied to the input pad by gloved fingers, bare fingers, styli, pens pencils, or any object capable of applying a force to the window. Fifth, the sensors may be configured to measure both the magnitude of the applied force, and also the location on the input pad where the force was applied. Sixth, the input pad and the base support may comprise a relatively thin planar configuration that can be easily affixed to typical display monitors or used as a stand alone interface device. Seventh, the configuration of the input pad and the one or more sensors is relatively insensitive to forces applied parallel to the input pad. Lastly, the force-based input device can detect and register forces applied to either side of the input pad, and can accurately determine the magnitude and location of the applied force.

Each of the above-recited advantages will be apparent in light of the detailed description set forth below, with reference to the accompanying drawings. These advantages are not meant to be limiting in any way. Indeed, one skilled in the art will appreciate that other advantages may be realized, other than those specifically recited herein, upon practicing the present invention.

As illustrated inFIGS. 1 and 2, a force-based input device10in accordance with an exemplary embodiment of the present invention is shown. The input device can have a base support14having an outer periphery18. A plurality of apertures20,22,24, and26can be formed in the base support14within the periphery18. The apertures20,22,24, and26can be located along the periphery18and can circumscribe and define a substantially rectangular input pad50, shown by dashed lines inFIG. 1. The plurality of apertures can also define a plurality of isolated beam segments,30,32,34, and36, near the corners of, and parallel to the sides of the input pad50. Two sensors (see sensors30a,30b,32a,32b,34a,34b,36aand36b) can be attached along each isolated beam segment30,32,34, and36, respectively. The sensors30a,30b,32a,32b,34a,34b,36aand36bare configured to detect and measure a force applied to the input pad50. In addition, the sensors30a,30b,32a,32b,34a,34c,36aand36bare configured to output an electronic signal through a transmission device40attached or otherwise related to the sensors30a,30b,32a,32b,34a,34b,36aand36b, which signal corresponds to the applied force as detected by the sensors.

In one exemplary embodiment, the sensors30a,30b,32a,32b,34a,34c,36aand36beach comprise a strain gage configured to measure the strain within or across each of the respective isolated beam segments30,32,34, and36. Moreover, although each isolated beam segment30,32,34, and36is shown comprising two sensors located or disposed thereon, the present invention is not limited to this configuration. It is contemplated that one, two or more than two sensors may be disposed along each of the isolated beam segments depending upon system constraints and other factors. In addition, it is contemplated that the sensors may be comprised of the beam segments themselves, if appropriately configured. The sensor are discussed in greater detail below.

The transmission device40is configured to carry the sensors' output signal to one or more signal processing devices, shown as signal processing device44, wherein the signal processing devices function to process the signal in one or more ways for one or more purposes. For example, the signal processing devices may comprise analog signal processors, such as amplifiers, filters, and analog-to-digital converters. In addition, the signal processing devices may comprise a micro-computer processor that feeds the processed signal to a computer, as shown inFIG. 2. Or, the signal processing device may comprise the computer48, itself. Still further, any combination of these and other types of signal processing devices may be incorporated and utilized. Typical signal processing devices are known in the art and are therefore not specifically described herein.

Processing means and methods employed by the signal processing device for processing the signal for one or more purposes, such as to determine the coordinates of a force applied to the force-based touch pad, are also known in the art. Various processing means and methods are discussed in further detail below.

With reference again toFIGS. 1 and 2, the base support14is shown comprising a substantially flat, or planar, pad or plate. The base support14can have an outer mounting surface60and an inner mounting surface64that can lie essentially within the same plane in a static condition. The outer mounting surface60can be located between the periphery18and the apertures20,22,24, and26. The inner mounting surface64can be located between the input pad50and the apertures20,22,24, and26. The isolated beam segments30,32,34, and36can connect the inner mounting surface64with the outer mounting surface60. The outer mounting surface60can be mounted to any suitably stationary mounting structure configured to support the input device10. The input pad50can be a separate structure mounted to the inner mounting surface64, or it may be configured to be an integral component that is formed integrally with the inner mounting surface64. In the embodiment where the input pad is a separate structure, one or more components of the input pad can be configured to be removable from the inner mounting surface. For example, the input pad50may comprise a large aperture formed in the base support14, and a removable force panel configured to be inserted and supported within the aperture, which force panel functions to receive the applied force thereon from either direction.

The base support14can be formed of any suitably inelastic material, such as a metal, like aluminum or steel, or it can be formed of a suitably elastic, hardened polymer material, as is known in the art. In addition, the base support14may be formed of glass, ceramics, and other similar materials. The base support14can be shaped and configured to fit within any type of suitable interface application. For example, the base support can be configured as the viewing area of a display monitor, which is generally rectangular in shape. In addition, the base support14can be configured to be relatively thin so that the touch surface of the input pad of the base support is only minimally offset from the viewing area of a display monitor, thereby minimizing distortion due to distance between the input pad and the display monitor.

It is noted that the performance of the input device may be dependent upon the stiffness of the outer portion or outer mounting surface of the base support14. As such, the base support14, or at least appropriate portions thereof, should be made to comprise suitable rigidity or stiffness so as to enable the input device to function properly. Alternatively, instead of making the base support14stiff, the base support14, or at least a suitable portion thereof, may be attached to some type of rigid support. Suitable rigidity functions to facilitate more accurate input readings.

The input pad50can be a substantially flat, or planar, pad or plate and can lie within the same plane as the base support14. The input pad50can be circumscribed by the apertures20,22,24, and26.

The input pad50is configured to displace in response to various stresses induced in the input pad50resulting from application of a force, shown as arrow54inFIG. 2, acting on the input pad50. The input pad50is further configured to transmit the stresses induced by the applied force54to the inner mounting surface64and eventually to the isolated beam segments30,32,34, and36where resulting strains in the isolated beam segments are induced and measured by the one or more sensors.

The base support14and input pad50can have a first side80and a second side82. The present invention force-based input device10advantageously provides for the application of force to either the first or second sides80and82of the input pad50, and the input pad50may be configured to displace out of the plane of the base support14in either direction in response to the applied force54.

The input pad50can be formed of any suitably rigid material that can transfer, or transmit the applied force54. Such a material can be metal, glass, or a hardened polymer, as is known in the art.

The isolated beam segments30,32,34, and36can be formed in the base support14, and may be defined by the plurality of apertures20,22,24, and26. The isolated beam segments30,32,34, and36can lie essentially in the same plane as the base support14and the input pad50when in a static condition. In some embodiments, the apertures20,22,24, and26may be configured to extend all the way through the base support14. For example, the apertures20,22,24, and26can be through slots or holes. In other embodiments, the apertures20,22,24, and26may be configured to extend only partially through the base support14.

As illustrated inFIG. 1, the isolated beam segment32can be formed or defined by the apertures22and24. Aperture22can extend along a portion of the periphery18and have two ends22aand22b. The aperture24can extend along another portion of the periphery and have two ends24aand24b. Portions of the two apertures22and24can extend along a common portion of the periphery18where one end22bof aperture22overlaps an end24aof aperture24. The two ends22band24a, and the portions of the apertures22and24that extend along the common portion of the periphery18, can be spaced apart on the base support14a pre-determined distance. The portion of the aperture22that extends along the common portion of the periphery18can be closer to the periphery18than portion of the aperture24that extends along the common portion of the periphery18. The area of the base support14between the aperture22and the aperture24, and between the end22band the end24a, can define the isolated beam segment32.

The isolated beam segments30,34, and36can be similarly formed and defined as described above for isolated beam segment32. Isolated beam segment30can be formed by the area of the base support14between the apertures24and20, and between the ends24aand20a. Isolated beam segment34can be formed by the area of the base support14between the apertures24and26, and between the ends24band26b. Isolated beam segment36can be formed by the area of the base support14between the apertures26and20, and between the ends26aand20b. Thus, all of the isolated beam segments can be defined by the various apertures formed within the base support14. In addition, the isolated beam segments may be configured to lie in the same plane as the plane of the input pad50and base support14, as noted above.

The plurality of apertures20,22,24, and26can nest within each other, wherein apertures22and26extend along the sides90and92of the rectangular base support14, and can turn perpendicular to the short sides90and92and extend along at least a portion of the sides94and96of the base support14. Apertures20and24can be located along a portion of the sides94and96of the base support14and closer to the input pad50than apertures22and26. Thus, apertures20and24can be located or contained within apertures22and26. Stated differently, the apertures may each comprise a segment that overlaps and runs parallel to a segment of another aperture to define an isolated beam segment, thus allowing the isolated beam segments to comprise any desired length.

With respect toFIG. 1a, an alternative exemplary embodiment of the present invention input device10is illustrated. This particular embodiment is similar to the one described above and shown inFIG. 1, only the apertures20and24are located closer to the periphery18than apertures22and26. In other words, apertures20and24are configured to lie outside the apertures22and26.

As illustrated inFIG. 3, the isolated beam segments30,32,34, and36can have an outer or periphery juncture70, formed with the outer mounting surface60, and an inner juncture74, formed with the inner mounting surface64of the base support14, as shown for isolated beam segment32inFIG. 3. The inner juncture74and outer juncture70are configured to receive and concentrate the stresses induced on the base support14by the applied force54by deflecting or bending in opposite directions. Upon the application of a force to the input pad50, the resultant forces are transmitted through the input pad50to the various isolated beam segments as a result of the configuration of the isolated beam segments, and specifically the inner and outer junctures70and74, in relation to the input pad50and the inner mounting surface64. For example, returning toFIGS. 1 and 2, when a force is applied to the input pad50, the input pad50displaces and induces stresses in the input pad50. These stresses can be transmitted from the input pad50to the inner mounting surface64, and ultimately to the isolated beam segments30,32,34, and36. Upon receiving the forces or stresses, the isolated beam segments30,32,34, and36are configured to deflect in response to the displacement of the input pad50in response to the force being applied to the input pad50. Thus, the force applied to the input pad50and the resultant stresses induced in the input pad50can be directed to and concentrated in the isolated beam segments30,32,34, and36. The concentrated stresses can result in deflection of the isolated beam30,32,34, and36segments, and the deflection can be measured by the sensors30a,30b,32a,32b,34a,34b,36aand36b. The combination of providing isolated beam segments, and particularly isolated beam segments that lie in or substantially in the same plane as the input pad, and configuring the input device to concentrate the stresses on the input pad within the isolated beam segments, as well as the coplanar or substantial coplanar relationship of the force sensors with the touch surface or input pad, provides significant advantages over prior related input devices, including, but not limited to, being able to create the entire input device, including the mounting elements, from a single piece of material by means of appropriately positioning the apertures in the material; being able to reduce the sensitivity to longitudinal forces or moments transmitted to the touch surface; being mechanically simple; being able to eliminate preload springs; being able to provide a rugged and robust design that protects the input device from the environment; being able to minimize size and weight by making the sensors integral with and coplanar to the input pad; and being able to register forces from either side of the input pad. Furthermore, ceramic piezoelectric transducers deployed in the more sensitive longitudinal mode with the strain applied perpendicular to the axis of the poles and parallel to the electrodes makes the sensors more sensitive to elongation or strain and less sensitive to shear and transverse forces, thereby reducing the need for elaborate mechanisms to isolate the transducers from unwanted forces and moments.

The sensors30a,30b,32a,32b,34a,34b,36aand36bcan be located along each isolated beam segment30,32,34, and36essentially in the same plane as the base support14and the input pad50when in a static condition. Specifically, as shown inFIGS. 1 and 2, a sensor can be located at each end of each isolated beam segment. Thus, a sensor30acan be located on an isolated beam segment30near the end22aof one aperture22. Similarly, another sensor30bcan be located on the isolated beam segment30near the end20aof the aperture20. The sensors32aand32bcan be located on isolated beam segment32near each aperture end22band24arespectively. The sensors34aand34bcan be located on isolated beam segment34near each aperture end26band24brespectively. The sensors36aand36bcan be located on isolated be segment36near each aperture end26aand20brespectively.

The sensors30a,30b,32a,32b,34a,34b,36aand36bcan also be located along each isolated beam segment30,32,34, and36in a different plane than the base support14and the input pad50when in a static condition. The sensors30a,30b,32a,32b,34a,34b,36aand36bdo not necessarily have to be in the same plane as the input pad50, but preferably lie within the same plane with respect to one another. A plane containing all the sensors30a,30b,32a,32b,34a,34b,36aand36bis hereinafter referred to as the sensor plane. For example, an isolated beam segment having a side in the same plane as the input pad50, and a side in an offset plane from the input pad50can have the sensor plane located on the side that is in the same plane as the input pad50, or can have the sensor plane located on the side that is offset, but parallel to the plane of the input pad50.

The sensors30a,30b,32a,32b,34a,34b,36aand36bare configured to measure the deflection in the isolated beam segments30,32,34, and36caused by the applied force54on the input pad50. The sensors30a,30b,32a,32b,34a,34b,36aand36bcan be any type of sensor capable of measuring properties related to displacement of the isolated beam segments30,32,34, and36. For example, the sensors can be strain gages, capacitance gages, liquid level gages, laser level gages, or any suitable gage as is known in the art. The sensors30a,30b,32a,32b,34a,34b,36aand36bcan generate an electrical signal corresponding to the displacement of the isolated beam segments30,32,34, and36. The electrical signal can be transmitted from the sensors30a,30b,32a,32b,34a,34b,36aand36bvia a transmission means.

The transmission means40may comprise a wired or wireless transmission means, including for example, electrical wires40as shown inFIG. 2, radio transmitter, or optical communication devices, as known in the art. The transmission means40is configured to carry the signal output by each of the various sensors to a processing means44and48configured to receive and analyze the signal to determine the location and magnitude of the applied force54on the input pad50. The processing means and analysis methods can be any known in the art.

The present invention force-based input device may comprise several different embodiments, each of which function in a similar manner as the exemplary embodiment described above. Several specific embodiments are shown in the figures and set forth herein, however, these are not intended to be limiting in any way. It is contemplated that other embodiments may fall within the scope of the present invention that are not specifically set forth herein. With reference toFIG. 4, illustrated is a force-based input device100including a plurality of apertures120,122,124, and126that defines a substantially rectangular input pad150and the isolated beam segments130,132,134, and136are defined near the corners of, and at an angle to the sides of the input pad150. It is believed that orienting the isolated beam segments130,132,134, and136at an angle to the sides of the apertures120,122,124, and126further enhances the stress concentrating ability of the isolated beam segments130,132,134, and136. Namely, the stresses induced in the isolated beam segments130,132,134, and136have a higher magnitude and provide a more reliable analysis of the location and magnitude of the force applied to the input pad150. In addition, more symmetrical distortion may be realized by this design.

Illustrated inFIG. 4ais an alternative embodiment of the input pad illustrated inFIG. 4and described above. Specifically, each aperture120,122,124, and126can have a portion160on each end that angles toward the adjacent aperture. For example, the end portions160of aperture124can be angled toward the apertures122and126respectively. Each aperture can then turn perpendicular to the angled portion and extend away from input pad150, thus defining the plurality of isolated beam segments130,132,134, and136at angles to the sides of the input pad.

With reference toFIG. 5, illustrated is a force-based input device200including a plurality of apertures220,222,224, and226that define a rectangular input pad250and the isolated beam segments230,232,234, and236are defined near the center of, and parallel to the sides of the input pad250. Each of the apertures220,222,224, and226comprises a dog leg220a,222a,224a, and226aon one end that extends away from the input pad250and encloses those ends220b,222b,224b, and226bof the adjacent aperture not comprising a dog leg. It is believed that defining the isolated beam segments230,232,234, and236near the center of, and parallel to the sides of the apertures220,222,224, and226de-sensitizes the stress concentrating ability of the isolated beam segments230,232,234, and236. Namely, the stresses induced in the isolated beam segments230,232,234, and236can have a lower magnitude and allow a greater force to be applied to the input pad250without overloading the sensors. In addition, centering the isolated beam segments along the edges may make the sensor(s) located on these beam segments less sensitive to distortion, such as that resulting from diagonal warping of the base support. However, when the sensor(s) is/are touched near the corners the outputs can become negative. As a result, this configuration may be subject to increased distortions from other effects, such as warping of the input pad250.

Illustrated inFIG. 5ais an alternative embodiment of the input pad illustrated inFIG. 5and described above. In this embodiment, aperture224can have two ends224aand224bthat do not have dog legs. The dog leg ends of apertures222and226can encompass the aperture224.

With reference toFIG. 6, illustrated is a corner of a force-based input device300including a plurality of apertures324and326that define a rectangular input pad350having an isolated beam segment330defined near the corner of, and parallel to the sides of the input pad350. The plurality of apertures324and326can have perpendicular extensions that abruptly change directions, such as directional apertures390,392,394,396, occurring at the locations of the sensors330aand330b. It is believed that providing abrupt directional apertures390,392,394,396oriented in an orthogonal direction with respect to the longitudinal orientation of the isolated beam segments near the location of the sensors further enhances the stress concentrating ability of the isolated beam segments. In addition, providing such abrupt directional apertures is believed to provide a gradient that functions to smooth out the strain across the beam segments. More specifically, these abrupt directional apertures function to make more uniform the stresses and resulting strains in the direction perpendicular to the isolated beam segments. Although the beam segment330comprises apertures390,392,394, and396of an abrupt directional change that are shown as being perpendicular to the beam segment330, other aperture orientations are contemplated, such as apertures oriented at acute or orthogonal angles with respect to the longitudinal orientation of the beam segment330.

Illustrated inFIG. 6ais an alternative embodiment of the input pad illustrated inFIG. 6and described above. The plurality of apertures324and326can have perpendicular direction changes390, and394corresponding to the locations of the sensors330aand330b.

With reference toFIG. 7, illustrated is a force-based input device400including a plurality of apertures424and426that define a rectangular input pad450having isolated beam segments430defined near the corner of, and parallel to the sides of the input pad450. The plurality of apertures424and426comprise a change in width and increase ii size along the isolated beam segments430. This increase in size is represented by apertures410and412. It is believed that this change in width adjacent to isolated beam segments enhances the stress concentrating ability of the isolated beam segments.

With reference toFIG. 8, illustrated is a force-based input device500including a plurality of apertures524and526that can define a rectangular input pad550and two adjacent isolated beam segments534and536near the corner of, and parallel to the sides of the input pad550. The aperture526can have two parallel legs526aand526bthat extend perpendicularly away from the aperture526and toward the adjacent aperture524. The aperture524can extend between the parallel legs and split the isolated beam into two parallel segments534and536. It is believed that having two adjacent and parallel isolated beam segments534and536enhances the measurement accuracy of the sensors.

Illustrated inFIG. 8-Bis an alternative embodiment of the input pad illustrated inFIG. 8-Aand described above. The aperture524can have a dog leg524athat extends perpendicularly away from the aperture526and toward the periphery518. The dog leg can turn perpendicularly toward the adjacent aperture526so that the dog leg524aand the aperture524can extend, spaced apart and parallel, toward the adjacent aperture526. The aperture526can perpendicularly change direction toward the aperture524and can extend between the parallel dog leg524aand aperture524and split the isolated beam into two segments534and536.

Illustrated inFIG. 8-Cis an alternative embodiment of the input pad illustrated inFIG. 8-Aand described above. The parallel legs526aand526bof the aperture526can have perpendicular directional changes570and572at their ends. It is believed that the perpendicular directional changes570and572enhance the stress concentration ability of the isolated beam segments. In addition, the perpendicular directional changes in the apertures function to smoothen the stress and resulting strain, therefore making these more uniform, in the direction perpendicular to the isolated beam segments. Furthermore, the reduction in stress concentration due to the perpendicular direction changes can increase the degree of force overload the input pad can withstand without permanent damage.

Illustrated inFIG. 8-Dis an alternative embodiment of the input pad illustrated inFIG. 8-Band described above. The dog leg524aand aperture524can have perpendicular directional changes574and576at their ends. It is believed that the perpendicular directional changes574and576enhance the stress concentration ability of the isolated beam segments. Similar to that ofFIG. 8cthe perpendicular directional changes in the apertures function to smoothen the stress and resulting strain, therefore making these more uniform, in the direction perpendicular to the isolated beam segments.

With reference toFIGS. 9-11, illustrated are several force-based input devices that incorporate various stress concentrating features with the isolated beam segments, which stress concentrating features may be used in combination with the several aperture configurations described herein.FIG. 9illustrates notches610,612,614, and616in the plurality of apertures624and626adjacent the location of the sensors.FIG. 10illustrates holes710and712that are cut in the isolated beam segment734underneath the location of the sensors734aand734b.FIG. 11illustrates notches810and812cut in the isolated beam segment834underneath the location of the sensors834aand834b.

With reference toFIG. 12, illustrated is an isolated beam segment932formed in support base914, which isolated beam segment932has associated with it four sensors that are operable to determine the location and magnitude of an applied force. The sensors are shown as strain gauges932a,932b,932cand932d, arrayed in a full bridge configuration (seeFIG. 12-A), which is well known in the art for its advantages, such as for doubling the output, and others. This particular configuration of sensors functions to enhance the measurement accuracy of the sensors, collectively, in determining the location and magnitude of a force applied to the input pad.

With reference toFIG. 13, illustrated is a force-based input device1000including a plurality of apertures1020,1022,1024, and1026that can define a rectangular input pad1050and isolated beam segments1030,1032,1034and1036near the corner of, and parallel to the sides of the input pad1050. Aperture1020can extend along a side and around a corner of the input pad wherein the portion of the aperture that extends around the corner encloses a portion of aperture1022. Aperture1022can extend along a side and around a corner of the input pad wherein the portion of the aperture that extends around the corner encloses a portion of aperture1024. Aperture1024can extend along a side and around a corner of the input pad wherein the portion of the aperture that extends around the corner encloses a portion of aperture1026. Aperture1026can extend along a side and around a corner of the input pad wherein the portion of the aperture that extends around the corner encloses a portion of aperture1020. The plurality isolated beam segments1030,1032,1034, and1036can be defined by the enclosed portion of the apertures.

Illustrated inFIG. 13ais an alternative embodiment of the input pad illustrated inFIG. 13and described above. Aperture1020can extend along a side and around a corner of the input pad wherein the portion of the aperture that extends around the corner can be enclosed a portion of aperture1022. Aperture1022can extend along a side and around a corner of the input pad wherein the portion of the aperture that extends around the corner can be enclosed a portion of aperture1024. Aperture1024can extend along a side and around a corner of the input pad wherein the portion of the aperture that extends around the corner can be enclosed a portion of aperture1026. Aperture1026can extend along a side and around a corner of the input pad wherein the portion of the aperture that extends around the corner can be enclosed a portion of aperture1020.

Although the exemplary embodiments discussed above and shown in the drawings depict various exemplary force-based input devices having linear geometric configurations, it is contemplated that other exemplary force-based input devices may comprise nonlinear geometries, or a combination of these. It is further contemplated that the force-based input device may comprise virtually any arbitrary geometry.FIGS. 14-17illustrate several different exemplary embodiments of force-based input devices having different geometric configurations. It is noted that these embodiments can be configured to function in a similar manner as other force-based input devices described elsewhere herein. As such, a detailed description of their geometry, and not their function, is provided.

Specifically,FIG. 14illustrates a force-based input device according to still another exemplary embodiment, which is similar in function to those discussed above. However, in this particular embodiment the force-based input device1100comprises a base support1114having a nonlinear geometric configuration in the shape of an oval. In addition, curved apertures1120,1122,1124, and1126are formed in the base support1114, which apertures function to define a plurality of isolated beam segments, shown as beam segments1130,1132,1134, and1136, as well as an input pad1150. The force based input device1100further comprises a plurality of sensors operable with each isolated beam segment. The curved apertures are configured to be parallel with a perimeter or periphery of the base support. However, this is not required. The apertures may be formed at any orientation with respect to the periphery of the base support. In addition, the apertures may comprise any type of spline configuration.

FIG. 15illustrates a force-based input device according to still another exemplary embodiment, which, again, is similar in function to those discussed above. However, in this particular embodiment the force-based input device1200comprises a base support1214having a linear geometric configuration in the shape of a square. In addition, curved apertures1220,1222,1224, and1226are formed in the base support1214, which apertures function to define a plurality of isolated beam segments, shown as beam segments1230,1232,1234, and1236, as well as a substantially circular input pad1250. The force based input device1200further comprises a plurality of sensors operable with each isolated beam segment.

FIG. 16illustrates a force-based input device according to still another exemplary embodiment, which, again, is similar in function to those discussed above. However, in this particular embodiment the force-based input device1300comprises a base support1314having a linear geometric configuration in the shape of a pentagon. In addition, linear apertures1320,1322,1324,1326, and1328are formed in the base support1314, which apertures function to define a plurality of isolated beam segments, shown as beam segments1330,1332,1334,1336, and1338, as well as an input pad1350having a substantially pentagonal geometry. The force-based input device1300further comprises a plurality of sensors operable with each isolated beam segment. The plurality of apertures are formed or configured to be parallel to the periphery of the base support.

FIG. 17illustrates a force-based input device according to still another exemplary embodiment, which, again, is similar in function to those discussed above. However, in this particular embodiment the force-based input device1400comprises a base support1414having an arbitrary shape. In addition, apertures1430,1432,1434, and1436are formed in the base support1414, which apertures function to define and plurality of isolated beam segments, shown as beam segments1430,1432,1434, and1436, as well as an arbitrarily-shaped input pad1450. The force-based input device1400further comprises a plurality of sensors operable with each isolated beam segment. This embodiment illustrates how the support base and the apertures formed therein may comprise any arbitrary, spline configuration or geometry.

FIGS. 18-20illustrate several force-based input devices in accordance with still other exemplary embodiments of the present invention. As shown in these figures, the apertures formed within the base supports are not configured to overlap or extend beyond one another to form or define the isolated beam segments as in the other force-based input devices discussed above. Rather, the isolated beam segments are each formed or defined by two terminal ends of two different apertures and the approximation of these ends to one another. As such, the isolated beam segments defined by the apertures are much shorter in length.

FIG. 18illustrates an force-based input device1500having a support base1514and a plurality of apertures formed therein, shown as apertures1520,1522,1524, and1526. These apertures function similar to those described elsewhere herein, namely to define a plurality of isolated beam segments, shown as isolated beam segments1530,1532,1534, and1536, as well as to define an input pad1550. The apertures are configured such that each of their opposing terminal end is in close proximity with a terminal end of another aperture. However, unlike the other exemplary force-based input devices described above, none of the apertures are configured so that a segment of that aperture overlaps a segment of another aperture in a parallel manner. As such, the isolated beam segments are not formed by these overlapping segments. Instead, the isolated beam segments of the force-based input device1500are defined by the terminating ends of two apertures. Since these terminating ends are configured to be in close proximity to one another, the isolated beam segments are defined by that portion of the support base extending between the terminal ends of the two apertures. The isolated beam segments formed in this manner are shorter in length than would otherwise be in the case of overlapping aperture segments as their length is approximately that of the width of the apertures. In the specific embodiment shown inFIG. 18, the ends of each aperture terminate prior to joining the adjacent aperture, thus creating an isolated beam segment. One or more sensors may be located within or about the formed beam segment, which sensors are intended to function in a similar manner as described above.

FIG. 19illustrates a similar configuration, except the force-based input device1600comprises horizontal apertures1620and1624, formed in support base1614, having ends that extend beyond the vertical location vertical apertures1622and1626a distance x1. Furthermore, vertical apertures1622and1626comprise ends that terminate prior to intersecting or joining the horizontal apertures1620and1624, which termination results in a gap having a distance x2. Again, the apertures, and particularly their ends being in close proximity to one another function to define a plurality of isolated beam segments, shown as isolated beam segments1630,1632,1634, and1636. In addition, located within or about the isolated beam segments is one or more sensors configured to be operable with the isolated beam segments as discussed herein. Again, the apertures are also configured to define the isolated beam segments, as well as the input pad1650.

FIG. 20illustrates an exemplary force-based input device1700similar to the one described above and shown inFIG. 19, except that the ends of the horizontal apertures1720and1724, formed in support base1714, do not extend beyond the vertical location of the vertical apertures1722and1726. Instead, the ends of the horizontal apertures terminate at the vertical location of the vertical apertures. A gap or distance x2is still maintained as the vertical apertures do not intersect or join the horizontal apertures, which gap or distance represents the isolated beam segments, shown as isolated beam segments1730,1732,1734, and1736, each of which are operable with one or more sensors as located thereon or thereabout. The various apertures also define the input pad1750.

FIG. 21illustrates a force-based input device1800in accordance with still another exemplary embodiment of the present invention. In this particular embodiment, the input device1800can have a base support1814having an outer periphery1818. A plurality of apertures1820,1822,1824, and1826can be formed in the base support1814within the periphery1818. The apertures1820,1822,1824, and1826can be located along the periphery1818and can define a substantially rectangular input pad1850formed about the periphery1818, as delineated by dashed lines inFIG. 21. The plurality of apertures can also define a plurality of isolated beam segments,1830,1832,1834, and1836, near the corners of, and parallel to the sides of the input pad1850, each of which may be operable with one or more sensors as shown.

The base support1814is shown comprising a substantially flat, or planar, pad or plate. The base support1814can have an outer mounting surface1860and an inner mounting surface1864that can lie essentially within the same plane in a static condition. The outer mounting surface1860can be located between the periphery1818and the apertures1820,1822,1824, and1826, as well as between the input pad1850and the various apertures. In other words, the input pad1850may be configured to circumscribe the outer mounting surface1860. The inner mounting surface1864can be located inside of, or in other words circumscribed by, the various apertures. The isolated beam segments1830,1832,1834, and1836can connect the inner mounting surface1864with the outer mounting surface1860. The outer mounting surface1860can be mounted to any suitably stationary mounting structure configured to support the input device1810. The input pad1850can be a separate structure mounted to the outer mounting surface1860, or it may be configured to be an integral component that is formed integrally with the outer mounting surface1860.

The input pad1850, as supported about and integral with the periphery1818is configured to displace in response to various stresses induced in the input pad1850resulting from application of a force acting on the input pad1850. The input pad1850is further configured to transmit the stresses induced by the applied force to the outer mounting surface1860and eventually to the isolated beam segments1830,1832,1834, and1836where resulting strains in the isolated beam segments are induced and measured by the one or more sensors.

Essentially, the input device embodiment illustrated inFIG. 21is similar to that shown inFIG. 1, except that the input pad ofFIG. 21is located about the perimeter or periphery of the input device with the inner and outer mounting surfaces being positioned inside or interior to the input pad. In other words, the input device ofFIG. 21may be considered to comprise a structural configuration that is the inverse of the input device shown inFIG. 1. This particular embodiment is intended to illustrate that the present invention broadly contemplates a first structural element supported in a fixed position, and a second structural element operable with the first structural element, wherein the second structural element is dynamically supported to be movable with respect to the first structural element to define an input pad configured to displace under an applied force.

A method for making a force-based input device includes providing a base support capable of receiving an applied force. Apertures can be formed through the base support to define a input pad, and a plurality of isolated beam segments. The isolated beam segments can receive resultant forces transmitted the input pad when the input pad is displaced by an applied load. At least two sensors can be attached to each of the isolated beam segments to measure the forces transmitted from the input pad to the periphery. The sensors can output a signal corresponding to the applied force that can be used to determine the location and magnitude of the force applied to the input pad by means and methods known in the art.

A method for determining the location and magnitude of a force on a touch pad can include providing a base support having a periphery and a plurality of apertures that define a input pad. The input pad can be displaced by applying a force to the input pad. The force applied to the input pad can be transmitted by the input pad to a plurality of isolated beam segments, formed by the plurality of apertures. The isolated beam segments can be configured to receive resultant forces transmitted to the isolated beam segments by the displacement of the input pad. The transmitted forces can be measured by at least two sensors, located along each of the isolated beam segments. The sensors can be configured to output a signal corresponding to the applied force. The signal can be used to determine the location and magnitude of the force applied to the input pad by various processing means and methods, such as those known in the art.

As indicated above, the present invention features one or more processing means configured to process the signal output from the various sensors for one or more purposes, such as to determine the coordinates of the force being applied to the force-based touch pad, or to improve accuracy readings by accounting for and correcting changes in baseline activity. For example, the force signal sample from the sensors can be averaged from the beginning of the touch until either a specified time elapses or the force waveform crosses zero, at which time the location can be calculated. Other methods for determining the touch coordinates can include mapping the total force signal by a weighting function and integrating from the beginning of the touch to the end of the touch, waiting for the total force to exceed a specified threshold, averaging or integrating the sensor signal between specified points either of force level or time, estimating the peak of the total applied force, or pre-determining the preferred time of measurement.

With reference toFIGS. 22-24, illustrated are various block and flow diagrams of a signal processing method according to one exemplary embodiment. Specifically, with reference toFIG. 22, the sensor signals are first conditioned to correct the baseline, calibrate the sensor, equalize the time response, filter the noise, and correct for sampling time errors. The conditioned signals from all of the sensors are then summed to form the total force signal. The total force signal is then mapped into the time domain by a weighting function. Each conditional signal is then multiplied by the weighting factor and the weighted signals are then integrated beginning at the start of the touch until the end of the touch. The results are then used to calculate the location and magnitude of the applied force.

FIG. 23is similar to that shown inFIG. 22, only here, the processing method takes into account that most methods of calculating the spatial touch coordinates are insensitive to the scale factor of the sensor signals. As such, dividing by the integral of the weighting factor is eliminated. Instead the signals are summed before being divided.

FIG. 24illustrates an exemplary method for implementing the process described above to measure the applied force. The sensor channels are sampled at regular intervals and after one sample from each sensor is obtained, the sensors are calibrated, corrected, filtered and equalized. The sum of the sensors is then calculated. If a touch in process is valid, and if all sensors are valid, the weighting factor is calculated from the sum of the sensors. The product of the weighting factor and the sensor value is added to each sensor signal input. The weighting factor is also added to the sensors input signal. When the touch has ended, the processor checks for acceptable accuracy of the measurement, divides by the weighting factor, and further processes the signals to calculate the location or coordinates and magnitude of the applied force.

Exemplary techniques for processing signals from the sensors are also disclosed in commonly owned U.S. patent application Ser. No. 11/402,985, U.S. Publication No. US-2006-0284856-A1) entitled “Sensor Signal Conditioning in a Force-Based Input Device,” and U.S. patent application Ser. No. 11/402,692, (now U.S. Pat. No. 7,337,085) entitled “Sensor Baseline Compensation in a Force-Based Touch Device,” each filed the same day as the present application and incorporated herein by reference.

Indeed, other processing means and methods may be employed by the present invention that are known to those skilled in the art. For example, U.S. Pat. No. 4,121,049 to Rober; and U.S. Pat. No. 4,340,772 to DeCosta et al. disclose and discuss exemplary processing methods that may be incorporated for use with the present invention. As such, the present invention should not be limited to any particular processing means or methods, as each of these is contemplated for use and may be implemented with the force-based touch pad of the present invention to perform its intended function of processing the signal(s) received from the various sensors for one or more purposes.

With reference toFIGS. 25 and 25b, illustrated are respective top and side cross-sectional views of a portion of a touch pad, wherein the touch pad comprises sealing means designed to protect the touch pad from foreign objects and other debris so that moisture, dust and so forth can not pass through the apertures, if they completely penetrate the screen. As shown, the touch pad1900comprises a flexible membrane1950attached to the inner and outer frame areas, shown as outer mounting surface1160and inner mounting surface1964adjacent the input pad1950, to cover or seal apertures1922and1924. The flexible membrane1954may be attached using an adhesive, such as adhesive1958, or any other suitable attachment means. Flexible membrane1954is intended to be exemplary only of a single type of sealing means. Indeed, other types of sealing means may be used to seal the touch pad1900, which are contemplated herein.

FIG. 26illustrates an alternative embodiment of a force-based touch pad2000, wherein piezoelectric sensors, more accurately transducers, are utilized in place of stain gauge sensors. In one exemplary configuration, piezoelectric transducers2036aand2036bmay be mounted so that they are electrically in series with one another. This mounting configuration, however, only works with electrically conductive substrates. As such, the force-based touch pad2000comprises an electrically conductive substrate. The piezoelectric transducers2036each comprise metallic electrodes (not shown) located on their top and bottom surfaces.FIG. 36illustrates electrical connectors2037-aand2037-b(e.g., solder or other material deposits) located on respective bottom surfaces of the piezoelectric transducers2036-aand2036-b. The bottom surfaces are configured to be in electrical contact with the substrate. The output connections are made at the top surfaces (not shown) of the transducers2036aand2036b.

The advantage of locating the electrodes on the top and bottom surfaces of the transducers parallel to the plane of the isolated beam segments is that this orientation is most sensitive to strain parallel to the base support. Most prior related force-based touch pads use piezoelectric sensors to measure force perpendicular to the electrode planes. This, however, makes the sensors sensitive to lateral forces. As a result, many of the prior related force-based touch pads use elaborate schemes to reduce the lateral forces applied to the sensors. In the present invention, there are no forces being applied in the perpendicular direction. Indeed, the transducers are configured to measure strain which occurs parallel to the base support.FIG. 26further illustrates that the electrical connection to the side facing the plate is made by contact with the plate. It is otherwise difficult to make this connection. The wires connected to the other side of each transducer are connected to the signal as a differential pair, much like the output of a strain gauge bridge.

The piezoelectric transducers2036may be formed of a polymer or ceramic material. In addition, the piezoelectric transducers2036comprise thin plates with the poles on opposite sides of the smallest dimension. One poled face is attached parallel with the input pad, which comprises the most sensitive orientation.

More specifically, while illustrative exemplary embodiments of the invention have been described herein, the present invention is not limited to these embodiments, but includes any and all embodiments having modifications, omissions, combinations (e.g., of aspects across various embodiments), adaptations and/or alterations as would be appreciated by those in the art based on the foregoing detailed description. The limitations in the claims are to be interpreted broadly based the language employed in the claims and not limited to examples described in the foregoing detailed description or during the prosecution of the application, which examples are to be construed as non-exclusive. For example, in the present disclosure, the term “preferably” is non-exclusive where it is intended to mean “preferably, but not limited to.” Any steps recited in any method or process claims may be executed in any order and are not limited to the order presented in the claims. Means-plus-function or step-plus-function limitations will only be employed where for a specific claim limitation all of the following conditions are present in that limitation: a) “means for” or “step for” is expressly recited; b) a corresponding function is expressly recited; and c) structure, material or acts that support that structure are not expressly recited, except in the specification. Accordingly, the scope of the invention should be determined solely by the appended claims and their legal equivalents, rather than by the descriptions and examples given above.