WO2011094213A1

WO2011094213A1 - Acoustic wave touch-actuated cursor-control system

Info

Publication number: WO2011094213A1
Application number: PCT/US2011/022423
Authority: WO
Inventors: Brian J. Truesdale
Original assignee: Illinois Tool Works Inc
Current assignee: Illinois Tool Works Inc
Priority date: 2010-02-01
Filing date: 2011-01-25
Publication date: 2011-08-04
Anticipated expiration: 2012-08-01

Abstract

A touch pad assembly includes a substrate having a contact surface, a plurality of acoustic wave switches formed in the substrate, each of the plurality of acoustic wave switches including an acoustic wave cavity and a touch surface on the contact surface, and a button extending from the contact surface between the plurality of acoustic wave switches. The button provides an anchoring position configured to be engaged by a user.

Description

ACOUSTIC WAVE TOUCH-ACTUATED CURSOR- CONTROL SYSTEM

RELATED APPLICATIONS

[0001] This application relates to and claims priority benefits from U.S. Provisional Patent Application No. 61/300,343 entitled "Acoustic Wave Touch- Actuated Cursor-Control System," filed February 1, 2010, which is hereby incorporated by reference in its entirety.

[0002] This application also makes reference to U.S. Patent Application No. 11/946,251 entitled "Acoustic Wave Touch Actuated System," filed November 28, 2007 (U.S. Patent Application Publication No. 2008/0198145), which is hereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

[0003] Embodiments of the present invention generally relate to an acoustic wave touch actuated system and more particularly to an acoustic wave touch actuated system that may be used to detect motion, including direction and speed, over a surface of a device. The embodiments of the present invention may be used to control a cursor on a screen, or as a joystick, for example.

BACKGROUND OF THE INVENTION

[0004] Many capacitive slider assemblies and laptop computer touch or mouse pads are configured to detect sliding motion. For example, an operator may slide a finger across the touch or mouse pad, and a processing unit within the laptop correlates that motion with respect to images shown on the screen of the laptop computer. Thus, as a user moves a finger over the touch or mouse pad, a cursor displayed on the screen may move in response to the movement of the finger over the touch or mouse pad.

[0005] Typically, touch or mouse pads and capacitive slider assemblies use capacitive sensors to detect a touch and corresponding movement. For example, a conventional touch or mouse pad includes a plurality of capacitive sensors to detect movement across the pad. However, capacitive sensors may be adversely affected by water or other such fluids on the surface of the touch or mouse pad. Additionally, conventional capacitive sensors are not able to distinguish between pressure levels. That is, a finger pressed into a conventional touch pad at a first force is detected the same as a finger pressed into the conventional touch pad at a second force.

[0006] Existing keyboards and mouse pad systems designed for rugged, challenging environments have certain drawbacks. For example, if a keyboard or mouse pad system is sealed, it has been found that functionality may be lacking. Conversely, if a keyboard or mouse pad system exhibits a high degree of functionality, it has been found that they are typically not sealed well.

SUMMARY OF THE INVENTION

[0007] Certain embodiments of the present invention provide a touch pad assembly that includes a substrate having a contact surface. A plurality of acoustic wave switches are formed in the substrate. Each of the plurality of acoustic wave switches includes an acoustic wave cavity and a touch surface on the contact surface.

[0008] A button extends from the contact surface between the plurality of acoustic wave switches. The button provides an anchoring position configured to be engaged by a user.

[0009] The button may include a semi- spherical base having a recessed engagement area. The button may be offset with respect to at least two of the plurality of acoustic wave switches.

[0010] Each touch surface may include a tactile target, such as a central pinhole or recess formed in each touch surface.

[0011] A transducer may be secured to a surface of each acoustic wave cavity opposite the touch surface. The transducer is configured to generate a trapped acoustic wave within the acoustic wave cavity. [0012] The plurality of acoustic wave switches may be arranged in rows and columns on the substrate. The rows and columns intersect to form the touch surfaces.

[0013] A spacer may connect to the substrate. A plurality of spring members may extend from the spacer toward the substrate. At least four transducers may be secured to at least four of the plurality of spring members, respectively.

[0014] A handle may connect to the substrate. In this manner, a joystick may be formed.

[0015] The plurality of acoustic wave switches may be arranged in a circle. Optionally, the plurality of acoustic wave switches may include four acoustic wave switches arranged as a cross.

[0016] Certain embodiments of the present invention provide a pad interface that includes a touch plate pad including a substrate having a contact surface. A plurality of acoustic wave switches are formed in the substrate. Each of the plurality of acoustic wave switches includes an acoustic wave cavity and a touch surface on the contact surface. Each touch surface may include a tactile target.

[0017] A button extends from the contact surface between the plurality of acoustic wave switches. The button provides an anchoring position configured to be engaged by a user. The button includes a semi-spherical base having a recessed engagement area configured to anchor the user's finger or thumb thereto. The button is offset with respect to at least two of the plurality of acoustic wave switches.

[0018] Certain embodiments of the present invention provide a touch pad assembly that includes a pad interface and a printed circuit board. The pad interface includes a substrate having a contact surface and four acoustic wave switches formed in the substrate defining four touch surfaces on the contact surface. Each of the acoustic wave switches includes an acoustic wave cavity. Each touch surface includes a tactile target. [0019] The pad interface also includes a central button extending from the contact surface between the four acoustic wave switches. The button provides an anchoring position configured to be engaged by a user. The button includes a semi- spherical base having a recessed engagement area configured to anchor the user's finger or thumb thereto. The button is offset with respect to upper and lower acoustic wave switches.

[0020] Four transducers are secured to or otherwise abut the four acoustic wave switches. The transducers are configured to generate trapped acoustic waves within each of the acoustic wave cavities.

[0021] The pad interface may also include a spacer secured to the substrate. The printed circuit board connects to the spacer and is in communication with the transducers.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

[0022] Figure 1 illustrates a side cross-sectional view of an acoustic wave switch.

[0023] Figure 2 illustrates a top plan view of an acoustically multiplexed touch screen pad.

[0024] Figure 3 illustrates a substrate supporting a densely packed array of acoustic wave switches.

[0025] Figure 4 illustrates an isometric exploded view of a pad interface, according to an embodiment of the present invention.

[0026] Figure 5 illustrates a front view of a touch pad plate, according to an embodiment of the present invention.

[0027] Figure 6 illustrates a rear view of a touch pad plate, according to an embodiment of the present invention.

[0028] Figure 7 illustrates a side view of a touch pad plate, according to an embodiment of the present invention. [0029] Figure 8 illustrates an isometric front view of a touch pad plate, according to an embodiment of the present invention.

[0030] Figure 9 illustrates an isometric rear view of a touch pad plate, according to an embodiment of the present invention.

[0031] Figure 10 illustrates an isometric view of a joystick, according to an embodiment of the present invention.

[0032] Figure 11 illustrates an isometric front view of a touch pad plate, according to an embodiment of the present invention.

[0033] Figure 12 illustrates an isometric rear view of a touch pad plate, according to an embodiment of the present invention.

[0034] Figure 13 illustrates a rear view of a touch pad plate, according to an embodiment of the present invention.

[0035] Before the embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of "including" and "comprising" and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof.

DETAILED DESCRIPTION OF THE INVENTION

[0036] Figure 1 illustrates a side cross-sectional view of an acoustic wave switch 10. Each acoustic wave switch 10 has an associated acoustic wave cavity, or resonator 12 that extends through the thickness b_s of a substrate 14. The acoustic wave cavity 12 is formed in the substrate 14 such that the mass per unit surface area of the acoustic wave cavity 12 is greater than the mass per unit surface area of the substrate 14 adjacent the acoustic wave cavity 12. In one embodiment, the mass per unit area of the substrate in the switch region is increased to form the acoustic wave cavity 12 by forming a thin plateau or mesa 16 on a surface of the substrate 14 that is parallel to the plane of the substrate 14 and/or a touch surface 18. The mesa 16 may be formed on a back surface 20 of the substrate opposite the touch surface 18 of the acoustic wave cavity 12. Alternatively, the mesa 16 may be formed on the touch surface 18. A transducer 22 may be mounted on, or abut into, a surface 24 of the acoustic wave cavity 12 to generate an acoustic wave that is substantially trapped or localized in the acoustic wave cavity 12. Although the transducer 22 is shown as mounted on the mesa 16, if the mesa 16 is formed on the touch surface 18 of the substrate, the transducer 22 may be mounted directly on the substrate surface of the acoustic wave cavity 12 opposite the mesa 16 so that the transducer 22 is on the backside of the substrate 14. Each transducer 22 of each acoustic wave switch 10 is electrically connected to a processing unit 26, such as a printed circuit board, and/or a sensing circuit 28.

[0037] Each acoustic wave switch 10 may use any type of acoustic wave capable of being substantially trapped in a particular acoustic wave cavity 12. For simplicity, the acoustic wave switch 10 may use a shear wave in a direction that is in the plane of the substrate 14, wherein the shear wave energy extends in a direction perpendicular to the plane of the substrate 14, that is, through the thickness of the substrate 14. A shear wave is advantageous because it is insensitive to liquids and other contaminants on the touch surface 18 of the acoustic wave switch 10. Because the fundamental or zeroth order mode of a horizontally polarized shear wave may not be substantially trapped, higher order shear wave modes are used in accordance with embodiments of the present invention. It should be appreciated that because the acoustic wave used is trapped, the wave is a standing wave. A standing wave has a number of advantages over an acoustic wave that propagates or travels along a path in a substrate. For example, propagating waves are not confined to the main path of propagation but can diffract off of the main path complicating touch detection. This is opposed to a standing wave which by its nature is confined to the area of a particular acoustic wave cavity 12. Because the acoustic wave is confined, touch detection is easily accomplished. Further, the wave energy of a propagating wave is not stored at any location along the path. Once the wave passes a point along the path, the wave is gone, thereby making timing and control critical for touch detection with propagating waves. There are no timing or control issues with a standing wave because the wave energy is stored in the particular acoustic wave cavity 12. Moreover, a propagating wave is not a resonating wave. As such, the wave energy decays as it travels. A standing wave is resonant so that the wave is reinforced and prolonged. As a result, the standing wave has a much greater amplitude than a wave that is not confined. The construction and operation of each acoustic wave cavity 12 is further described in United States Patent No. 7,106,310, entitled "Acoustic Wave Touch Actuated Switch" (the "'310 patent"), which is hereby incorporated by reference in its entirety.

[0038] Embodiments of the present invention provide a system and method of detecting pressure and movement with respect to a surface, such as a mouse pad, dial, keypad, or the like, that employs trapped energy concepts to create localized mechanical resonators, or acoustic wave cavities 12. The '310 patent discloses an acoustic wave switch that includes a substrate with an acoustic wave cavity, or resonator, formed therein such that the mass per unit area of the acoustic cavity is greater than the mass per unit area of the substrate adjacent the acoustic cavity. A transducer is mounted on the acoustic cavity for generating an acoustic wave that is substantially trapped in the cavity. A touch on the touch surface of the acoustic cavity absorbs acoustic wave energy and produces a detectable change in the impedance of the transducer. Moreover, as a user touches the touch surface, the resonant frequency changes, which may be detected by a processing unit which is electrically connected to the transducer.

[0039] The acoustic wave switch described in the '310 patent has a high Q (the ratio of the stored energy to lost or dissipated energy over a complete cycle) so as to enable a touch to be detected by extremely simple, low-cost circuitry. The acoustic wave switch is rugged, explosion proof, operates in the presence of liquids and other contaminants (unlike capacitive sensors), has a lower power consumption and may be incorporated and integrally formed in a wall of a housing for a device.

[0040] Each acoustic wave switch 10 may be connected to an extremely simple touch detection or sensing circuit 28, such as shown and described in the '310 patent. For example, each transducer 22 associated with a respective acoustic wave switch 10 may be coupled to a multiplexer that sequentially couples the transducer 22 and its associated acoustic wave switch 10 to an oscillator, as discussed in the '310 patent. Embodiments of the present invention may detect a touch on a respective touch surface 18 through a detected change in impedance, as described in the '310 patent.

[0041] Optionally, contact on the touch surface 18 may be detected by measuring the decay time of the acoustic wave within the acoustic wave cavity 12. United States Patent No. 7,265,746, entitled "Acoustic Wave Touch Detection Circuit and Method" (the "'746 patent"), which is hereby incorporated by reference in its entirety, describes a controller that detects a sensed event such as a touch on an acoustic wave switch/sensor based on the decay time. The trapped acoustic wave within the acoustic wave/resonant cavity acts to "ring" the acoustic wave/resonant cavity. That is, as a voltage is applied to the transducer, the transducer operates to resonate the resonant cavity.

[0042] As described in the '746 patent, the sensing circuit 28 is operatively connected to the acoustic wave switch 10 and may include a controller that drives the transducer 22 to generate a resonant acoustic wave in the acoustic wave cavity 12 during a first portion of a sampling cycle. In a second portion of the sampling cycle, the controller monitors the time that it takes for the acoustic wave signal from the transducer 22 to decay to a predetermined level. Based on the decay time, the controller detects a sensed event, such as contact on the touch surface 18.

[0043] It has been discovered that acoustic wave switches 10 may be positioned close together on a substrate 14 without adversely affecting one another. The acoustic wave switches may be positioned close enough such that, during use, a finger or glove will be in contact with at least two acoustic wave switches 10 at a given time.

[0044] Figure 2 illustrates a bottom plan view of an acoustically multiplexed touch screen pad 30. Raised acoustic wave switches or resonators 32 are positioned on, or formed over, a substrate 33. As shown in Figure 2, the acoustic wave switches 32 are aligned on or over the substrate 33 such that the planes of the acoustic wave switches 32 and the substrate 33 are parallel with one another. Each acoustic wave switch 32 includes a transducer 22 coupled to one end. Four rows 34 of acoustic wave switches 32 intersect six columns 36 of acoustic wave switches 32. Optionally, more or less rows 34 and columns 36 may be used than those shown. For example, a system may use two rows that intersect two columns, such as shown in Figures 12 and 13, described below.

[0045] The intersections of the rows 34 and columns 36 of acoustic wave switches 32 form touch surfaces 38. Movement over each of the touch surfaces 38 is detected by the horizontally and vertically aligned transducers 22. Thus, less transducers 22 are needed (as compared to a non-multiplexed arrangement) due to the fact that changes will be detected by a combination of transducers 22 at the ends of the raised acoustic wave switches 32. For example, a finger positioned at a touch surface 38 represented by the intersection of the lowest row 34 and the leftmost column 36 produces a first impedance and/or decay that is detected by the transducer 22 of that row 34, while a second impedance and/or decay is detected with respect to the transducer 22 of the column 36. If the finger is moved, the detected impedances or acoustic decays with respect to the respective transducers change accordingly. Each acoustic wave switch 32 is operatively connected to a processing unit and/or sensing circuit, as discussed above.

[0046] Figure 3 illustrates a substrate 40 supporting a densely packed array of acoustic wave switches 10. As shown in Figure 3, the acoustic wave switches 10 are positioned at "North," "South," "East" and "West" positions.

[0047] Four acoustic wave switches 10, for example, are formed close together in the shape of a cross. A touching medium, such as a finger tip, glove tip, absorbing rubber ball, or the like, may span all four acoustic wave switches 10, and roll in a desired cursor direction. Consider two acoustic wave switches 10 of the cross, aligned along a N-S axis for example, and assume a finger tip placed at the center of the cross rolls to the Northwest thereby applying more pressure to the North and West acoustic wave switches 10 and less on the South and East. By comparing the North acoustic wave switch 10 response to the South acoustic wave switch 10 response, a N-S axis signal is generated. The same comparison is done between the E-W pair of acoustic wave switches 10, and the signals are vectorially added. As such, a simple cursor control system is created that can be operated by a finger or thumb tip. An absorbing overlay may be positioned over each acoustic wave switch 10 in order to make the sensor assembly act as a trackball or joystick. Pressure sensitivity may be utilized for both selection and speed determination of the cursor. The surface region that includes the four acoustic wave switches 10 may be contoured for optimum ergonomics.

[0048] During operation, a user positions a finger or thumb on the substrate 40 over the acoustic wave switches 10 or pads. The finger overlays portions of each one of the acoustic wave switches 10. As the user shifts finger pressure from the "West" and "South" acoustic wave switches 10 to the "East" and "South" pads, the impedances of the transducers and/or the measured rates of acoustic decay change accordingly. These changes are correlated to directional movement and rate of movement by a processing unit and/or sensing circuit to which the acoustic wave switches 10 are operatively connected.

[0049] Acoustic wave sensing, as described in the '310 patent and the '746 patent, has several operational advantages over capacitive sensors. First, the pressure sensitivity of the acoustic wave switches or resonators may be used to direct a cursor to a location using a slight sliding motion, then increasing the finger pressure to activate. For example, a user may exert a slight amount of pressure over the acoustic wave switches of the embodiments shown in Figures 2-3, for example, to move a cursor over a screen. When the user moves the cursor over a desired icon, such as an internet link, the user may exert additional pressure to open or activate that link. Exerting additional pressure may be ergonomically more appealing, smoother, and easier than clicking a button or double clicking a mouse pad, for example.

[0050] An additional operational advantage of the resonator pads is that they are not affected by water and other fluids on the control or touch surface. This is in stark contrast to conventional capacitive sensors.

[0051] Figure 4 illustrates an isometric exploded view of a pad interface 50, according to an embodiment of the present invention. The pad interface 50 includes a touch pad plate 52 that may be secured over a spacer 53, which, in turn, mechanically and electrically connects to a printed circuit board 55, which may include the central processing unit 26 and/or sensing circuit 28 discussed above with respect to Figure 1.

[0052] The touch pad plate 52 includes a contact surface 54 including touch surfaces 18 of acoustic wave switches 10. A center button or detent 56 is positioned between the touch surfaces 18. The center button 56 is not positioned on, in, or above the touch surfaces 18 of the acoustic wave switches 10. That is, the center button 56 is not a dome cover or otherwise part of any of the acoustic wave switches 10. As shown in Figure 4, the center button 56 is positioned at a midpoint between the left and right touch surfaces 18. However, the center button 56 may be closer to the top touch surface 18 than the lower touch surface 18.

[0053] The button 56 may be a semi- spherical protuberance extending outwardly from the contact surface 54. The button 56 may include a semi-spherical base 58 having an anchoring divot or recessed area 60 at a top surface.

[0054] The touch pad plate 52 may be a substrate on which the acoustic wave switches 10 are formed, as described above with respect to Figure 1. The touch pad plate 52 secures to the spacer 53 through fasteners 62.

[0055] Spring members 64, such as coil springs, that support transducers 22, extend outwardly from the spacer 53 toward the mesas (not shown in Figure 4) of the acoustic wave switches 10 of the touch pad plate 52. When the touch pad plate 52 is secured to the spacer 53, the transducers 22 abut into, and/or are secured to, the mesas of the acoustic wave switches 10.

[0056] Additionally, a central spring member 66 extends toward an underside of the button 56. As shown in Figure 4, however, the spring member 66 may not support a transducer.

[0057] The transducers 22 are configured to generate trapped acoustic waves within the acoustic wave switches 10, such as described above with respect to Figure 1. Moreover, finger or thumb movement with respect to the acoustic wave switches 10 is detected, as discussed above with respect to Figure 3. Pinholes or recesses 68 may be formed in the centers of each acoustic wave switch 10 to provide an operator with a reference target toward which to exert pressure.

[0058] Figure 5 illustrates a front view of the touch pad plate 52, according to an embodiment of the present invention. Figure 6 illustrates a rear view of the touch pad plate 52, according to an embodiment of the present invention. Figure 7 illustrates a side view of the touch pad plate 52, according to an embodiment of the present invention. Figure 8 illustrates an isometric front view of the touch pad plate 52, according to an embodiment of the present invention. Figure 9 illustrates an isometric rear view of the touch pad plate 52, according to an embodiment of the present invention.

[0059] As shown in Figures 5-9, the button 56 provides an anchoring position for an operator to place a thumb or finger. A thumb or finger may be positioned on the button 56 so that at least a portion of a thumb or finger surface extends into the recess 60 when the operator applies force therein.

[0060] As the operator pivots his/her thumb or finger towards the acoustic wave switches 10, detected impedances or decay times change with respect to each acoustic wave switch 10. As such, movement with respect to the contact surface 54 may be detected and correlated with respect to a cursor or other such item on a computer screen, as described above. [0061] The button 56 provides a home position on which an operator anchors his/her thumb or finger. Accordingly, the button 56 minimizes susceptibility of contacting an undesired portion of the contact surface 54.

[0062] Additionally, the spring members 64 and 66 (shown in Figure 4) may be used to provide additional feedback. For example, the spring members 64 and 66 compress and extend based on changing pressure. That is, when a user presses down toward a particular acoustic wave switch 10, the spring member 64 will compress, while the other spring members 64 will compress or extend in response thereto. As such, the relative lengths of the spring members 64 and 66 (as the central spring member 66 may also compress and contract) may change, thereby affecting the detected impedances or acoustic decays of the trapped acoustic waves within the acoustic wave cavities 12.

[0063] Referring to Figures 4-9, optionally, the spring members 64 and 66 may not be used. Instead, the transducers 22 may be positioned between the face of the spacer 53 and the mesas 16. Additionally, the system may, alternatively, not use the spacer 53 at all, but instead simply have the touch pad plate 52 include the transducers 22 secured to the mesas 16, with the touch pad plate 52 connecting to the printed circuit board 55.

[0064] The central button 56 allows for easy thumb pivoting with respect to the acoustic wave switches 10. The anchoring recess 60 provides, in essence, a secure tactile area that anchors the thumb at a home position, and prevents the thumb from slipping over the contact surface 54 onto undesired areas. As the operator pivots his thumb or finger on the button 56, the acoustic wave switches 10 detect changing trapped wave impedances or decay rates. These changes are detected and are correlated to movement of a cursor or other such item on a computer monitor. The anchored, pivotal movement with respect to the button 56 allows a user to move a cursor, or operate a joystick, without actually sliding his/her finger or thumb to each touch surface 18 of each individual acoustic wave switch 10. [0065] The bottom acoustic wave switch 10 is offset with respect to the top acoustic wave switch 10. The button 56 is positioned closer to the top acoustic wave switch 10 than the bottom acoustic wave switch 10. It has been found that this offset allows for maximum lower thumb application force and provides for easier thumb activation in the down direction. That is, the offset provides an ergonomically-efficient configuration for the user. Nevertheless, the acoustic wave switches 10 may be positioned at different relative positions depending on a particular operator's preferences.

[0066] Figure 10 illustrates an isometric view of a joystick 70, according to an embodiment of the present invention. The joystick 70 includes the pad interface 50 secured to a handle 72. An operator may grasp the handle 72 with his fingers. That is, the operator's fingers may longitudinally wrap around at least a portion of the handle 72. The operator may then engage the button 56 with his/her thumb. In this manner, the operator may securely and firmly engage the button 56 with his/her thumb while his/her hand securely grasps the handle 72, thereby allowing the operator to efficiently engage the pad interface 50.

[0067] Figure 11 illustrates an isometric front view of a touch pad plate 90, according to an embodiment of the present invention. Figure 12 illustrates an isometric rear view of the touch pad plate 90, according to an embodiment of the present invention. Referring to Figures 11-12, the touch pad plate 90 is configured similar to the touch screen pad 30 shown in Figure 2. Acoustic wave switches 92 are formed as rows intersect acoustic wave switches 94 configured as columns. A transducer 96 is positioned at one end of each row 92. Similarly, a transducer 96 is positioned at one end of each column 94. The intersection of the rows and columns provide target or touch areas, such as described above with respect to Figure 2.

[0068] The button 56 is then used as an anchoring home position for an operator. The operator may pivot his/her thumb on the button 56, as described above with respect to Figures 4-9, to move a cursor or other such item on a screen. [0069] Figure 13 illustrates a rear view of the touch pad plate 90. The four intersections are labeled A, B, C, and D. Areas A, B, C, and D are target areas towards which an operator may pivot his/her finger or thumb toward. The movement toward and/or away from these target areas is detected, as discussed above, and correlated to movement of a cursor or other such item on a computer monitor/screen.

[0070] Additionally, the embodiment shown in Figures 11-13 provides additional touch- sensitive areas E, F, G, and H. The operator may pivot his/her thumb toward these areas, and changes in impedance or decay time may be detected. The touch pad plate 90 provides four additional target areas E, F, G, and H in addition to A, B, C, or D while still using only four transducers 96. Accordingly, the touch pad plate 90 provides increased coverage of potential touch areas. The touch pad plate 90 provides eight target areas (A-H) while utilizing four transducers 96 that intersect at four areas (A- D).

[0071] Embodiments of the present invention, such as shown and described with respect to Figures 4-13, are capable of detecting variable forces applied on or toward target areas. If a first pressure is applied toward a first target area, movement of a cursor, for example, may move in that direction on a monitor at a first speed. With increased applied force toward the same target area, the speed of the cursor on the screen increases. With decreased applied force, the speed of the cursor on the screen decreases.

[0072] For example, the output of the embodiments shown and described with respect to Figures 4-13 may be a vector including X and Y coordinates of intended motion. The magnitude of the vector is a function of the pressure being applied.

[0073] Thus, embodiments of the present invention provide a pressure- sensitive acoustic-wave based system and method of moving a cursor or other such item on a computer monitor. The embodiments of the present invention may function as a more compact and efficient mousepad system.

[0074] Additionally, embodiments of the present invention may be used to directionally control various types of equipment. For example, the embodiment shown in Figure 10 may be used as a joystick for controlling a forklift, or other such device. Embodiments of the present may be used to replace traditional mechanical joysticks.

[0075] Unlike a conventional mouse or joystick, embodiments of the present invention may include minimal or no moving parts. As such, manufacture and operation may be more efficient than conventional devices.

[0076] Additionally, embodiments of the present invention may provide a pad interface and/or joystick that may be completely sealed, while at the same time providing heightened operational sensitivity.

[0077] Embodiments of the present invention are also smaller and lighter than traditional mouse pad systems and/or joysticks.

[0078] While various spatial terms, such as upper, lower, mid, lateral, horizontal, vertical, and the like may used to describe portions of the embodiments discussed above, it is understood that such terms are merely used with respect to the orientations shown in the drawings. The orientations may be inverted, rotated, or otherwise changed, such that an upper portion is a lower portion, and vice versa, horizontal becomes vertical, and the like.

[0079] Variations and modifications of the foregoing are within the scope of the present invention. It is understood that the invention disclosed and defined herein extends to all alternative combinations of two or more of the individual features mentioned or evident from the text and/or drawings. All of these different combinations constitute various alternative aspects of the present invention. The embodiments described herein explain the best modes known for practicing the invention and will enable others skilled in the art to utilize the invention. The claims are to be construed to include alternative embodiments to the extent permitted by the prior art.

[0080] Various features of the invention are set forth in the following claims.

Claims

1. A touch pad assembly comprising:

a substrate having a contact surface;

a plurality of acoustic wave switches formed in said substrate, each of said plurality of acoustic wave switches comprising an acoustic wave cavity and a touch surface on said contact surface; and

a button extending from said contact surface between said plurality of acoustic wave switches, wherein said button provides an anchoring position configured to be engaged by a user.

2. The touch pad assembly of claim 1, wherein said button comprises a semi- spherical base having a recessed engagement area.

3. The touch pad assembly of claim 1, wherein said button is offset with respect to at least two of said plurality of acoustic wave switches.

4. The touch pad assembly of claim 1, wherein each touch surface comprises a tactile target.

5. The touch pad assembly of claim 4, wherein said tactile target comprises a central pinhole.

6. The touch pad assembly of claim 1, further comprising a transducer secured to a surface of said acoustic wave cavity opposite said touch surface, wherein said transducer is configured to generate a trapped acoustic wave within said acoustic wave cavity.

7. The touch pad assembly of claim 1, wherein said plurality of acoustic wave switches are arranged in rows and columns on said substrate, wherein said rows and columns intersect to form said touch surfaces.

8. The touch pad assembly of claim 1, further comprising a spacer that connects to said substrate.

9. The touch pad assembly of claim 8, further comprising a plurality of spring members extending from said spacer toward said substrate.

10. The touch pad assembly of claim 9, further comprising at least four transducers secured to at least four of said plurality of spring members, respectively.

11. The touch pad assembly of claim 1, further comprising a handle connected to said substrate.

12. The touch pad assembly of claim 1, wherein said plurality of acoustic wave switches are arranged in a circle.

13. The touch pad assembly of claim 1, wherein said plurality of acoustic wave switches comprises four acoustic wave switches arranged as a cross.

14. A pad interface comprising:

a touch plate pad comprising a substrate having a contact surface;

a plurality of acoustic wave switches formed in said substrate, each of said plurality of acoustic wave switches comprising an acoustic wave cavity and a touch surface on said contact surface, wherein each touch surface comprises a tactile target; and a button extending from said contact surface between said plurality of acoustic wave switches, wherein said button provides an anchoring position configured to be engaged by a user, wherein said button comprises a semi-spherical base having a recessed engagement area configured to anchor the user's finger or thumb thereto, wherein said button is offset with respect to at least two of said plurality of acoustic wave switches.

15. The pad interface of claim 14, wherein said tactile target comprises a central pinhole.

16. The pad interface of claim 14, further comprising a transducer secured to a surface of said acoustic wave cavity opposite said touch surface, wherein said transducer is configured to generate a trapped acoustic wave within said acoustic wave cavity.

17. The pad interface of claim 14, wherein said plurality of acoustic wave switches are arranged in rows and columns on said substrate, wherein said rows and columns intersect to form said touch surfaces.

18. The pad interface of claim 14, further comprising a spacer that connects to said substrate.

19. The pad interface of claim 14, further comprising a handle connected to said substrate.

20. A touch pad assembly comprising:

a pad interface comprising:

a substrate having a contact surface;

four acoustic wave switches formed in said substrate defining four touch surfaces on said contact surface, each of said acoustic wave switches comprising an acoustic wave cavity, wherein each of said touch surfaces comprises a tactile target; and

a central button extending from said contact surface between said four acoustic wave switches, wherein said button provides an anchoring position configured to be engaged by a user, wherein said button comprises a semi- spherical base having a recessed engagement area configured to anchor the user's finger or thumb thereto, wherein said button is offset with respect to upper and lower acoustic wave switches;

four transducers secured to or abutting said four acoustic wave switches, wherein said transducers are configured to generate trapped acoustic wave within each of said acoustic wave cavities

a spacer secured to said substrate; and

a printed circuit board connected to said spacer and in communication with said transducers.