Patent Application
20150009185
The present disclosure relates to touch-sensitive devices, and in particular to touch systems and methods that employ acoustic sensing in a thin cover glass.
The market for displays and other devices (e.g., keyboards) having non-mechanical touch functionality is rapidly growing. As a result, touch-sensing techniques have been developed to enable displays and other devices to have touch functionality. Touch-sensing functionality is gaining wider use in mobile device applications, such as smart phones, e-book readers, laptop computers and tablet computers.
Touch systems in the form of touch screens have been developed that respond to a variety of types of touches, such as single touches, multiple touches, swiping, and touches. The main touch-sensing techniques are electrical (i.e., capacitance-based), optical and acoustic. While these main touch-sensing techniques are effective, there remains a need for improved approaches to touch-sensing that can provide the required sensitivity to sense touch events while also being able to accurately determine the location of and pressure at each touch event.
Additional features and advantages of the disclosure are set forth in the detailed description that follows, and in part will be readily apparent to those skilled in the art from that description or recognized by practicing the disclosure as described herein, including the detailed description that follows, the claims, and the appended drawings.
The claims as well as the Abstract are incorporated into and constitute part of the Detailed Description set forth below.
All publications, articles, patents, published patent applications and the like cited herein are incorporated by reference herein in their entirety.
Cartesian coordinates are shown in certain of the Figures for the sake of reference and are not intended as limiting with respect to direction or orientation.
The present disclosure can be understood more readily by reference to the following detailed description, drawings, examples, and claims, and their previous and following description. However, before the present compositions, articles, devices, and methods are disclosed and described, it is to be understood that this disclosure is not limited to the specific compositions, articles, devices, and methods disclosed unless otherwise specified, as such can, of course, vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only and is not intended to be limiting.
The following description of the disclosure is provided as an enabling teaching of the disclosure in its currently known embodiments. To this end, those skilled in the relevant art will recognize and appreciate that many changes can be made to the various aspects of the disclosure described herein, while still obtaining the beneficial results of the present disclosure. It will also be apparent that some of the desired benefits of the present disclosure can be obtained by selecting some of the features of the present disclosure without utilizing other features. Accordingly, those who work in the art will recognize that many modifications and adaptations to the present disclosure are possible and can even be desirable in certain circumstances and are a part of the present disclosure. Thus, the following description is provided as illustrative of the principles of the present disclosure and not in limitation thereof.
Disclosed are materials, compounds, compositions, and components that can be used for, can be used in conjunction with, can be used in preparation for, or are embodiments of the disclosed method and compositions. These and other materials are disclosed herein, and it is understood that when combinations, subsets, interactions, groups, etc. of these materials are disclosed that while specific reference of each various individual and collective combinations and permutation of these compounds may not be explicitly disclosed, each is specifically contemplated and described herein.
Thus, if a class of substituents A, B, and C are disclosed as well as a class of substituents D, E, and F, and an example of a combination embodiment, A-D is disclosed, then each is individually and collectively contemplated. Thus, in this example, each of the combinations A-E, A-F, B-D, B-E, B-F, C-D, C-E, and C-F are specifically contemplated and should be considered disclosed from disclosure of A, B, and/or C; D, E, and/or F; and the example combination A-D. Likewise, any subset or combination of these is also specifically contemplated and disclosed. Thus, for example, the sub-group of A-E, B-F, and C-E are specifically contemplated and should be considered disclosed from disclosure of A, B, and/or C; D, E, and/or F; and the example combination A-D. This concept applies to all aspects of this disclosure including, but not limited to any components of the compositions and steps in methods of making and using the disclosed compositions. Thus, if there are a variety of additional steps that can be performed it is understood that each of these additional steps can be performed with any specific embodiment or combination of embodiments of the disclosed methods, and that each such combination is specifically contemplated and should be considered disclosed.
The example touch system 10 of
In an example, glass sheet 30 is a chemically strengthened glass, such as Gorilla Glass®, made by Corning, Inc. of Corning, N.Y.
Assembly 20 includes a plurality of acoustic transducers 50. A first sub-set of acoustic transducers 50 are used as transmitters and are referred to as transmitters 50T, with the first subset defining a transmitter array 52T. A second sub-set is used as receivers and are referred to as receivers 50R, with the second subset defining a receiver array 52R. In an example, transmitters 50T are arranged adjacent sides 36A and 36B, while receivers 50R are arranged adjacent sides 36C and 36D. Glass sheet 30 is shown by way of example as being rectangular with four distinct sides, but other shapes (e.g., other polygonal shapes, circular, etc.) can be employed. Transmitters 50T and receivers 50R are generally arranged in pairs, with the receiver being directly across from the paired transmitter.
In an example, transmitters 50T and receivers 50R are arranged on either top surface 32 (
In an example, the acoustic wave 56 from a given transmitter 56 is received by between one and 100 receivers 50R, which includes the paired receiver. The number of receivers 50R that receive a given acoustic wave 56 depends on the distance separating the transmitters and receivers, the spacing between the receivers, and the directionality (i.e., divergence angle) of the acoustic wave.
In an example, acoustic transducers 50 are thin-film based and are formed directly on top surface 32 or bottom surface 34 of glass sheet 30. In an example, acoustic transducers 50 are IDT piezoelectric thin-film acoustic transducers each having an electrode 53 and interleaved digits 55, as shown in the close-up inset of
In an example, the IDT piezoelectric thin-film acoustic transducers 50 can be fabricated using first a thin-film process technique to deposit piezoelectric film 57, such as PVDF, on the top or bottom surfaces 32 or 34 of glass sheet 30. Either a wet process, such as a coating method, or a dry process, such as lamination of a thin piezoelectric film on the glass, can be employed. A printing technology, such as screen printing with the desired IDT pattern, can then be used to fabricate the IDT electrode 53 atop piezoelectric film 57.
Alternatively, the above two process can be reversed, i.e., printing the IDT electrode 53 first, then coating or laminating the piezoelectric film 57 atop the IDT electrode. Compared to conventional single-chip piezoelectric transducers, IDT-based acoustic transducers 50 have better frequency and acoustic mode selection, i.e., more accurate dispersion analysis for spatial resolution and pressure sensitivity. Example methods of forming IDT transducers 50 based on laminate piezoelectric films such as PVDF or copolymer P(VDF0.75−TrFE0.25) are describe in the article by Brown, L. F., “Design considerations for piezoelectric polymer ultrasound transducers,” IEEE Transactions on Ultrasonics, Ferroelectrics and Frequency Control, Vol. 47, Issue 6, November 2000, pp. 1377-1396.
Fabricating acoustic transducers 50 directly on the top or bottom surfaces 32 or 34 of glass sheet 30 eliminates sources of reflection, such as notches as used in conventional surface-acoustic wave (SAW) touch panels. Such notches can also weaken glass sheet 30 given that the glass sheet is relatively thin. It also simplifies the configuration of assembly 20 by obviating the need for reflection gratings and other ancillary structures used in the prior art to generate and direct acoustic waves.
In an example embodiment, acoustic transducers 50 are configured to generate acoustic waves 56 of frequency f in the low-dispersion A0 mode, wherein frequency f is in the range from 0.5 MHz to 5 MHz. This frequency range falls between the standard SAW frequency of nominally 5 MHz and the dispersive signal technology (DST) and acoustic pulse recognition (APR) frequencies that generally fall in the range from 20 kHz to 60 kHz. Operating in the frequency range for frequency f provides comparable pressure sensitivity and spatial resolution to SAW-based touch screens while also providing greater touch sensitivity and spatial resolution as compared to DST-based or APR-based touch systems.
The optimum frequency f within the stated frequency range depends on the thickness d of glass sheet 30.
In example embodiments of the disclosure such as illustrated in
With continuing reference to
In an example, controller 60 comprises a computer and includes a device, for example, a floppy disk drive, CD-ROM drive, DVD drive, magnetic optical disk (MOD) device (not shown), or any other digital device including a network connecting device such as an Ethernet device (not shown) for reading instructions and/or data from a computer-readable medium, such as a floppy disk, a CD-ROM, a DVD, a MOD or another digital source such as a network or the Internet, as well as yet to be developed digital means. The computer executes instructions embodied in a computer-readable medium (e.g., stored in firmware and/or software) to cause the controller to perform signal processing to determine at least one characteristic of at least one touch event TE.
The computer is programmable to perform functions described herein, including the operation of touch system 10 and any signal processing that is required to determine at least one characteristic of at least one touch event TE. As used herein, the term computer is not limited to just those integrated circuits referred to in the art as computers, but broadly refers to computers, processors, microcontrollers, microcomputers, programmable logic controllers, application-specific integrated circuits, FPGAs, and other programmable circuits, and these terms are used interchangeably herein.
Software may implement or aid in performing the touch location and pressure-sensing functions and operations disclosed herein, including in the execution of one or more algorithms for processing receiver signals SR to determine at least one characteristic of at least one touch event TE. The software may be operably installed in controller 60 or processor 62. Software functionalities may involve programming, including executable code, and such functionalities may be used to implement the methods disclosed herein. Such software code is executable by the general-purpose computer or by one or more processors, e.g., processor 62.
In operation, the software code and possibly the associated data records are stored within a general-purpose computer platform, within the processor unit, or in local memory. At other times, however, the software may be stored at other locations and/or transported for loading into the appropriate general-purpose computer systems. Hence, the embodiments discussed herein involve one or more software products in the form of one or more modules of code carried by at least one machine-readable medium. Execution of such code by a processor of the computer system or by the processor unit enables the platform to implement the catalog and/or software downloading functions, in essentially the manner performed in the embodiments discussed and illustrated herein.
The computer and/or processor 62 may each employ a computer-readable medium or machine-readable medium, which refers to any medium that participates in providing instructions to a processor for execution, including for example, determining at least one characteristic associated with a touch event TE, as explained below. Any memory discussed below constitutes a computer-readable medium. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic disks, such as any of the storage devices in any computer(s) operating as one of the server platforms, discussed above. Volatile media include dynamic memory, such as main memory of such a computer platform. Physical transmission media include coaxial cables; copper wire and fiber optics, including the wires that comprise a bus within a computer system. In an example, processor 62 comprises an FPGA programmed with hardware description language (HDL) or comprises one or more application-specific logic integrated circuits (ASICs).
Common forms of computer-readable media therefore include, for example: a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, less commonly used media such as punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge, a carrier wave transporting data or instructions, cables or links transporting such a carrier wave, or any other medium from which a computer can read programming code and/or data. Many of these forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to a processor for execution.
In an example, controller 60 also employs a high-speed pulse generator, such as an ultrasound transmit pulser (e.g. the LM96550 from Texas instruments, Inc. Austin, Tex.) to provide transmit signals ST that cause transmitters 50T to generate acoustic waves 56. Also in an example embodiment, controller 60 includes a multi-channel ultrasound amplifier/ADC device, such as the 8-channel I/Q demodulator model AD9279 from Analog Devices, to control the operation of receivers 50R. The model AD9279 includes a variable gain amplifier (VGA) with a low noise preamplifier (LNA), an antialiasing filter (AAF), an analog-to-digital converter (ADC), and an I/Q demodulator with programmable phase rotation.
Controller 60 is thus adapted to trigger transmitters 50T to generate acoustic waves 56 and acquire the corresponding receiver signals from receivers 50R. The acquired receiver signals SR are processed by controller 60 using a reconstruction algorithm to determine at least one characteristic of each touch event TE. This sequence is continuously repeated at frequency γ for real time monitoring of the touch events TE.
Controller 60 is also configured to receive and process the receiver signals SR to create a “map” of glass sheet 30, including a baseline map of unperturbed acoustic signals 56 through the glass, as well as a map of deviations and a threshold that is used to indicate the occurrence of one or more touch events TE. Tables 1A, 2A, 1B and 2B set forth below and
Assembly Interfaced with a Display Panel
A layer 110 of transparent acoustic-absorbing material (e.g., epoxy or film) is disposed atop light-emitting side 82 of display panel 80. Assembly 20 is disposed adjacent layer 110 and is spaced apart therefrom, such as by the use of a spacer 120, to define an air gap 130. Example materials for layer 110 include.
With reference to
The example touch screen system 10 of
In an example operation of touch system 10, controller 60 sequentially activates transmitters 50T to generate acoustic waves 56 of frequency f that travel through glass sheet 30 to one or more receivers 50R. As noted above, acoustic waves 56 can be transmitted in acoustic-wave pulses 56W having a pulse frequency γ. Receivers 50R detect acoustic waves 56 and in response generate receiver signals SR representative of the amount of acoustic energy received.
In the absence of a touch event TE, the resulting receiver signals SR represent a “no touch event” baseline that can be compared with other receiver signals SR taken later in time to determine if some of the receiver signals have been attenuated, and if the attenuation is sufficient (i.e., is greater than a threshold attenuation) to indicate the occurrence of a touch event TE. It is also noted that the strength (i.e., amplitude A) of acoustic waves 56 can vary between transmitters 50T and the detection efficiently of the acoustic waves can vary between receivers 50R.
Consequently, prior to operating touch system 10 to detect one or more touch events TE, touch system 10 is operated in a “no touch event” calibration mode so that the receiver signals SR can be normalized. Further, the baseline readings can be taken during system operation to account for any system drifts. Since normalized values for receiver signals SR are between 0 and 1, the receiver signal attenuation αR can be defined as αR=−ln(SR).
In a first example embodiment, a method called the “line method” is used to identify a touch location TE(x,y). In the line method, glass sheet 30 is divided into an imaginary pixel grid 100 of n pixels p, as shown in the close-up view of assembly 20 of
With reference to
where αji are coefficients proportional to length of line Lj within pixel pi. The pixels pi along a line Lj that has bj=0 are assigned an attenuation Xi=0.
This serves to define a set of linear equations corresponding to lines Lj having non-zero attenuation. In the case of just a few touch events TE, the number of lines Lj can be greater than number of remaining pixels to solve. If this is the case, a direct or an iterative solution can be employed. For example, a suitable iterative algorithm is called the algebraic reconstruction technique (ART) algorithm, and an even faster version is called the simultaneous algebraic reconstruction technique (SART).
Where just a few lines Lj are involved (i.e., just a few receivers 50R detect a given acoustic wave 56 from a given transmitter 50T), a first example algorithm proceeds as follows:
The data obtained by processing the receiver signals SR using the above method can also be processed to obtain additional information about the touch event TE, such as a touch-event occurrence, a touch-event location, a touch-event duration, a touch-event pressure, and a time-evolution of the touch-event pressure.
In another example embodiment, a second method referred to herein as the “projection method” employs an algorithm based on the use of Radon transforms as known in the art (and used in tomography applications) is used to determine the occurrence of a touch event TE, as well as additional characteristics of the touch event. The method includes three main steps. The first main step involves collecting data from receivers 50T for one direction of acoustic waves 56, e.g., those traveling from transmitters' 50T adjacent side 36A to receivers 50R adjacent side 36C. This set of data is called a “projection.”
In applications where high accuracy is required, many projections are needed to construct an accurate attenuation map that shows the touch event TE. In our case, we can treat all parallel lines connecting transmitters 50T and receivers 50R as one projection. For example, if the acoustic wave 56 from each transmitter 50T is detected by three receivers 50R on the opposite side of glass substrate 30, there are a total of 3+3=6 projections.
Next, in the second main step, the parallel lines are sorted by spatial coordinate x. If a single projection with angle θ is denoted as fθ(x), then a filter in the frequency domain is applied, wherein Fθ(ω) is the Fourier transform of fθ(x) and Rθ(ω)=|ω|·F(ω) is the Radon transform of the projection in the frequency domain. Returning to spatial domain, rθ(x) is inverse Fourier transform of Rθ(ω). Note that here the x axis is orthogonal to the projection. In other words, the touch event TE is projected onto the x axis.
Once rθ(x) for several angles (projections) is determined, the third main step involves combining rθ(x) into a reconstructed image of the touch event TE. For any given point (x,y) within the touch event TE, all radon transforms (r) of projections of that point are added (all projection lines passing through the point). Interpolation can be employed to obtain a finer grid. The result is an attenuation map.
Once the attenuation map is established, the touch events TE are determined using steps 6) through 8 from the first example algorithm.
The configuration for assembly 20 of
Tables 1A and 1B below set forth exemplary data obtained by simulation for the amplitude of receiver signals SR for a given transmitter-receiver pair for the case where there is no touch event TE. That is, the data in Tables 1A and 1B are baseline data or a baseline “map.” Note that the maximum signal values are on the diagonal of the Tables 1A and 1B and illustrate that the direct-line transmission of acoustic wave 56 (e.g., TY1 to RY1, TY2 to RY2, etc.) between the transmitter-receiver pair has the strongest amplitude.
Note that TX and TY are reversed here as compared to the data provided in the PPT information provided because the coordinates are reversed.
1.31
1.32
1.18
0.76
1.1
1.39
1.34
1.38
1.98
2.03
2.71
2.16
1.82
1.97
2
1.76
1.31
1.32
1.18
1.39
1.34
1.38
1.98
2.03
2.71
2.16
1.97
2
1.76
The amount of pressure PTE associated with a given touch event TE can be deduced by performing a calibration wherein different amounts of pressure are applied to different locations on glass sheet 30. A look-up table of signal attenuation versus pressure PTE versus touch location TL(x,y) can be constructed. Interpolation can be used to provide data for a large number of touch locations in between actual measured touch locations. Once a touch event TE is detected and its location TL(x,y) identified, then the signal data can be analyzed to ascertain the amount of pressure PTE for the touch location.
The time-evolution of the pressure PTE(t) can be determined by examining the signal data for different times and noting the change in the signal values. The aforementioned look-up table can be used to establish the pressure PTE(t) for a given time associated with the duration of the touch event. The various values of PTE for different times are then used to define PTE(t). In an example illustrated in
Although the embodiments herein have been described with reference to particular aspects and features, it is to be understood that these embodiments are merely illustrative of desired principles and applications. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the appended claims.
This application claims the benefit of priority under 35 U.S.C. §119 to U.S. Provisional Application Ser. No. 61/843,612, filed on Jul. 8, 2013, the content of which is relied upon and incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61843612 | Jul 2013 | US |
