Patent Application
20080198145
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.
Capacitive slider assemblies and laptop computer touch or mouse pads are currently 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.
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.
Embodiments of the present invention provide an improved system and method of detecting pressure and movement over a surface, such as may be used, for example, with respect to a computer (e.g., a touch or mouse pad of a laptop computer), and various other applications.
Certain embodiments of the present invention provide a touch pad system that may include a sensing device (such as a processing unit and/or sensing circuit), a substrate and a plurality of acoustic wave switches. The plurality of acoustic wave switches are positioned with respect to the substrate, with each of the acoustic wave switches including a touch surface connected to an acoustic wave cavity and a transducer secured to a side of the acoustic wave cavity that may be opposite the touch surface. The sensing device is in communication with each transducer. The plurality of acoustic wave switches are positioned to provide detection of sliding motion direction and rate between the plurality of acoustic wave switches. Adjacent acoustic wave switches are positioned close enough with respect to one another so that a finger tip touches both at the same time during operation.
The acoustic wave switches may be oriented in a linear fashion, arranged in a circle, arranged in a plurality of rows, or various other configurations. The plurality of acoustic wave switches may be arranged in rows and columns on the substrate, wherein the rows and columns intersect to form the touch surfaces.
The plurality of acoustic wave switches may include four acoustic wave switches arranged as a cross, wherein a finger overlays a portion of each of the four acoustic wave switches during operation. A user may then shift the finger over the four acoustic wave switches. The detected changes in amplitude, impedance, resonant frequency or decay rate of the acoustic wave switches is used to determine movement of the finger over the four acoustic wave switches.
The sensing device receives signals from the plurality of acoustic wave switches such that varying touch pressures are capable of being distinguished. For example, the transducer generates an acoustic wave that is trapped in the acoustic wave cavity. A touch on the touch surface absorbs the wave energy and changes the amplitude, decay rate, impedance or resonant frequency. The detected change depends on the amount of pressure (i.e., force exerted by a touch) applied to the touch surface.
Certain embodiments of the present invention also provide a touch pad system that includes one or both of a processing unit and/or a sensing circuit, and first and second acoustic wave switches. The acoustic wave switches are spaced from one another such that a finger may contact both of the acoustic wave switches simultaneously. The processing unit and/or the sensing circuit recognizes a touch on the first acoustic switch as a first value, a touch on the second acoustic wave switch as a second value, and a touch on both of the first and second acoustic wave switches simultaneously as a third value. The first, second and third values are correlated to a position of a finger on the touch pad system.
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.
Each acoustic wave switch 12 may use any type of acoustic wave capable of being substantially trapped in a particular acoustic wave cavity 20. For simplicity, the acoustic wave switch 12 is described using 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 28 of the acoustic wave switch 12. 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 20. 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 20. 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 20 is further described in U.S. Pat. No. 7,106,310, entitled “Acoustic Wave Touch Actuated Switch” (The “'310 patent”), which is hereby incorporated by reference in its entirety.
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, using active touch that employs trapped energy concepts to create localized mechanical resonators, or acoustic wave cavities 20. 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.
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.
With respect to
Optionally, embodiments of the present invention may detect a touch on a respective touch surface 28 by measuring the decay time of the acoustic wave within a particular acoustic wave cavity 20. United States Patent Application Publication No. 2004/0246239, entitled “Acoustic Wave Touch Detection Circuit and Method” (the “'239 application”) 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 cavity, or resonator, acts to “ring” the acoustic cavity. That is, as a voltage is applied to transducer, the transducer operates to resonate the acoustic cavity.
As described in the '239 application, the sensing circuit 42 operatively connected to an acoustic wave switch 12 may include a controller that drives the transducer 26 to generate a resonant acoustic wave in the acoustic wave cavity 20 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 26 to decay to a predetermined level. Based on the decay time, the controller detects a sensed event, such as a touch on the touch surface 28 of the acoustic wave switch 12.
Referring to
It has been discovered that acoustic wave switches 12 may be positioned close together on a substrate 14 without adversely affecting one another. The acoustic wave switches, or resonators 12 may be positioned close enough such that, during use, a finger or glove will be in contact with at least two acoustic wave switches 12 at a given time. The distance d between two acoustic wave switches 12 is small enough to ensure that a finger tip or glove tip will be in contact with at least two acoustic wave switches 12 during operation, thereby providing, by signal interpolation, a response from discrete sensors operatively connected to the transducers 26 that is continuous along a line of acoustic wave switches 12. For example, the acoustic wave switches 121 and 122 may be less than ⅛″ from one another. As noted above, the processing unit 40 and/or sensing circuit 42 is operatively connected to each transducer 26. As such, the processing unit 40 and/or the sensing circuit 42 are able to detect which acoustic wave switches 12 are being touched. Therefore, the processing unit 40 and/or the sensing circuit 42 are able to determine which direction the touching medium, e.g., a finger tip, is moving and how fast it is moving over the linear slider pad 10.
As a finger tip moves from left to right over the first two acoustic wave switches 121 and 122, the detected impedance or rate of acoustic decay of the first two acoustic wave switches 121 and 122 changes as the finger tip moves from left to right. For example, at time t1, a majority of a surface area of a user's finger tip may be over the acoustic wave switch 121, while a smaller portion is over the acoustic wave switch 122. As such, the processing unit 40 and/or sensing circuit 42 detects a first impedance or rate of decay with respect to the acoustic wave switch 121 that is different than the detected impedance or rate of decay with respect to the acoustic wave switch 122. At time t2, as the user moves the finger from left to right, a majority of the surface area of the user's finger shifts over the acoustic wave switch 122, while a smaller portion is over the acoustic wave switch 121. Thus, at time t2, the detected impedance or rate of decay with respect to the acoustic wave switches 121 and 122 is different than at time t1. The processing unit 40 and/or sensing circuit 42 detects the change in impedance or rate of decay from time t1 to time t2 with respect to both acoustic wave switches 121 and 122. These impedance or rate of decay changes with respect to the acoustic wave switches 12 is correlated to directional movement and rate of movement. That is, as the detected impedances or rates of decay with respect to adjacent acoustic wave switches 12 change, the processing unit 40 and/or the sensing circuit 42 correlate the detected changes to directional movement and rate of movement.
For example, if the processing unit 40 and/or sensing circuit 42 detects a first set of changes of impedance or rate of decay for acoustic wave switches 121 and 122, the processing unit 40 and/or sensing circuit 42 determines that a touching medium, e.g., a finger, is moving in a first direction at a first rate. If the rate of change of impedance or rate of decay with respect to the acoustic wave switches 121, and 122 varies, then the processing unit 40 and/or sensing circuit 42 determines that the finger is moving from left to right, or right to left, at a different rate. In general, touch detection algorithms may be adapted so that pressure variable responses result in continuous or discrete level pressure sensors.
With respect to acoustic decay, for example, as the touch surface 28 of an acoustic wave switch 12 is touched, acoustic wave energy is absorbed by the touch. Thus, the resonance of the acoustic wave within the acoustic wave cavity 20 decays. The time of the decay is correlated to a threshold voltage and the processing unit 40 counts the number of cycles it takes between the transducer 26 “striking” the acoustic wave cavity 20 and the particular decayed level. When the acoustic wave switch 12 is touched, the acoustic wave cavity 20 rings down faster and the threshold voltage occurs at a smaller count. Thus, the measure of whether the acoustic wave cavity 12 has been touched or not is based on the count. As a finger is slid over the acoustic wave switches 12 on the substrate 14, the acoustic wave switch 12 that the finger is leaving will be dampened less, and the acoustic wave switch 12 toward which the finger is moving will be dampened more (as such, the count for that pad will be decreasing because of the increased dampening). The processing unit 40 and/or the sensing circuit 42 detect the dampening changes and correlate that to directional movement and rate of movement over the linear slider pad 10.
The intersections of the rows 74 and columns 76 of acoustic wave switches 72 form touch surfaces 78. Movement over each of the touch surfaces 78 is detected by the horizontally and vertically aligned transducers 26. Thus, less transducers 26 are needed (as compared to a non-multiplexed arrangement) due to the fact that changes will be detected by a combination of transducers 26 at the ends of the raised acoustic wave switches 72. For example, a finger positioned at a touch surface 78 represented by the intersection of the lowest row 74 and the leftmost column 78 produces a first impedance and/or decay that is detected by the transducer 26 of that row 74, while a second impedance and/or decay is detected with respect to the transducer 26 of the column 76. If the finger is moved, the detected impedances or acoustic decays with respect to the respective transducers changes accordingly. Each acoustic wave switch 72 is operatively connected to a processing unit and/or sensing circuit, as discussed above.
As shown in
During operation, a user positions a finger on the substrate 80 over the acoustic wave switches 12 or pads. That is, the finger overlays portions of each one of the acoustic wave switches 12. As the user shifts finger pressure from the “West” and “South” acoustic wave switches 12 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 12 are operatively connected.
The acoustic wave cavity or resonator pads, rows, or columns shown and described with respect to
The signal processing techniques described above are analogous to those used in capacitive slider and mouse applications. The mouse pad in a laptop computer, as noted above, includes a series of capacitive sensors having circuit board traces in both horizontal and vertical directions and uses interpolation to create a smooth response.
A linear and circular resonator sensor system, such as shown in
Active touch sensing, as described in the '310 patent and the '239 application and used with the embodiments described with respect to
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.
Embodiments of the present invention use trapped energy resonators/acoustic wave cavities for rugged, sealed, pressure sensitive cursor control in metals, ceramics and plastics. The sliding sensors may be used to set and vary lighting, appliance heating elements, electronic devices, and the like. Certain embodiments of the present invention may be used, for example, as mouse touch pads for laptop computers.
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.
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.
Various features of the invention are set forth in the following claims.
This application relates to and claims priority benefits from U.S. Provisional Patent Application No. 60/902,278 entitled “Acoustic Wave Touch Actuated System,” filed Feb. 20, 2007, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60902278 | Feb 2007 | US |
