Patent Publication Number: US-11051112-B2

Title: Multiple audio transducers driving a display to establish localized quiet zones

Description:
RELATED APPLICATION 
     The present disclosure claims priority to U.S. Provisional Patent Application Ser. No. 62/615,145, filed Jan. 9, 2018, which is incorporated by reference herein in its entirety. 
    
    
     FIELD OF DISCLOSURE 
     The present disclosure relates in general to a mobile device, and more particularly, to using one or more mechanical transducers to drive a display to generate audio and one or more other mechanical transducers to drive the display to establish localized audio quiet zones. 
     BACKGROUND 
     Traditionally, a small speaker (typically referred to as a “receive,” “rec” or “Rx” speaker) generates audio playback of a mobile device in a “phone call” mode of the device. In many mobile designs, this receive speaker was located at an upper front face of the device, generally located behind a front panel of the device with a small slot provided to localize the sound when a user of the device holds the device to the user&#39;s ear. 
     With the advent of touch-screen controlled devices, featuring full edge-to-edge glass fronts with displays beneath, the receive speaker was often enabled by forming a slot into the front glass and situating the speaker behind the slot, with the active display area stopping short of the area of the receive speaker. This reverse side mounting and venting (amongst other front facing functions) prevents the active display area from becoming fully as large as the glass itself, typically leading to inactive (dark) areas at the top and/or bottom of the mobile device. As full edge-to-edge mobile designs emerge, alternate solutions are desired to bring audio signals to the surface of the glass front without obscuring or otherwise compromising the display beneath the glass. 
     Multiple transducers may be used to enable surface audio in a display-based device, such that the surface of the display screen itself acts as an acoustic transducer to generate sound. In certain applications, it may be desired that only designated areas of a display are acoustically driven. For example, in a mobile device used close to the ear, it may be desirable that the sound generated by the display surface is localized to the user&#39;s ear, for privacy purposes. However, the nature of display materials, which are typically mechanically stiff in nature, often results in the issue that even if driven at one corner or area of the display, the whole of the display tends to emit acoustically. This whole surface display design is very different from previous designs which have a speaker “firing” through a port in the top front portion of the phone, that creates a localized, point source of audio with minimum leakage to the immediate area outside the user&#39;s ear. 
     Thus, with a full surface of a display being driven, this audio leakage may compromise privacy on calls. In other words, others near a user may be able to hear audio that the user may not desire the others to hear. With traditional designs that use speakers and acoustic ports, people who are near the mobile device are typically unable to hear the received audio. Accordingly, methods and systems are desired for localizing display surface audio in a mobile device. 
     SUMMARY 
     In accordance with the teachings of the present disclosure, the disadvantages and problems associated with localizing surface-generated audio with a mobile device may be reduced or eliminated. 
     In accordance with embodiments of the present disclosure, a method for mechanically driving a display screen to produce acoustic sound may include mechanically driving a first mechanical transducer mechanically coupled to the display screen to generate acoustic sound from the display screen and controlling a second mechanical transducer mechanically coupled to the display screen at a specific location to apply an acoustic null to the specific location in order to localize generation of the acoustic sound from the display screen. 
     In accordance with embodiments of the present disclosure, a system for mechanically driving a display screen to produce acoustic sound may include a first mechanical transducer mechanically coupled to the display screen and configured to be mechanically driven in order to generate acoustic sound from the display screen and a second mechanical transducer mechanically coupled to the display screen at a specific location and configured to apply an acoustic null to the specific location in order to localize generation of the acoustic sound from the display screen. 
     Technical advantages of the present disclosure may be readily apparent to one having ordinary skill in the art from the figures, description and claims included herein. The objects and advantages of the embodiments will be realized and achieved at least by the elements, features, and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are examples and explanatory and are not restrictive of the claims set forth in this disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete understanding of the present embodiments and advantages thereof may be acquired by referring to the following description taken in conjunction with the accompanying drawings, in which like reference numbers indicate like features, and wherein: 
         FIG. 1A  illustrates a block diagram of selected components of an example mobile device, in accordance with embodiments of the present disclosure; 
         FIG. 1B  illustrates an exploded perspective view of selected components of an example mobile device, in accordance with embodiments of the present disclosure; 
         FIG. 2A  illustrates a side elevation view of selected components of an example mobile device, in accordance with embodiments of the present disclosure; 
         FIG. 2B  illustrates a top plan view of selected components of an example mobile device, in accordance with embodiments of the present disclosure; 
         FIG. 3  illustrates a circuit diagram of an example amplifier and mechanical transducer for generating acoustical sound via a screen surface, in accordance with embodiments of the present disclosure; 
         FIG. 4  illustrates a circuit diagram of an example amplifier and mechanical transducer for sensing mechanical energy and correcting for the sensed mechanical energy, in accordance with embodiments of the present disclosure; and 
         FIG. 5  illustrates a circuit diagram of another example amplifier and another mechanical transducer for sensing mechanical energy and correcting for the sensed mechanical energy, in accordance with embodiments of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  illustrates a block diagram of selected components of an example mobile device  102 , in accordance with embodiments of the present disclosure. As shown in  FIG. 1A , mobile device  102  may comprise an enclosure  101 , a controller  103 , a memory  104 , a user interface  105 , a microphone  106 , a radio transmitter/receiver  108 , a plurality of mechanical transducers  110 , and a plurality of amplifiers  112 . 
     Enclosure  101  may comprise any suitable housing, casing, or other enclosure for housing the various components of mobile device  102 . Enclosure  101  may be constructed from plastic, metal, and/or any other suitable materials. In addition, enclosure  101  may be adapted (e.g., sized and shaped) such that mobile device  102  is readily transported on a person of a user of mobile device  102 . Accordingly, mobile device  102  may include but is not limited to a smart phone, a tablet computing device, a handheld computing device, a personal digital assistant, a notebook computer, or any other device that may be readily transported on a person of a user of mobile device  102 . 
     Controller  103  is housed within enclosure  101  and may include any system, device, or apparatus configured to interpret and/or execute program instructions and/or process data, and may include, without limitation, a microprocessor, microcontroller, digital signal processor (DSP), application specific integrated circuit (ASIC), or any other digital or analog circuitry configured to interpret and/or execute program instructions and/or process data. In some embodiments, controller  103  may interpret and/or execute program instructions and/or process data stored in memory  104  and/or other computer-readable media accessible to controller  103 . 
     Memory  104  may be housed within enclosure  101 , may be communicatively coupled to controller  103 , and may include any system, device, or apparatus configured to retain program instructions and/or data for a period of time (e.g., computer-readable media). Memory  104  may include random access memory (RAM), electrically erasable programmable read-only memory (EEPROM), a Personal Computer Memory Card International Association (PCMCIA) card, flash memory, magnetic storage, opto-magnetic storage, or any suitable selection and/or array of volatile or non-volatile memory that retains data after power to mobile device  102  is turned off. 
     User interface  105  may be housed at least partially within enclosure  101 , may be communicatively coupled to controller  103 , and may comprise any instrumentality or aggregation of instrumentalities by which a user may interact with mobile device  102 . For example, user interface  105  may permit a user to input data and/or instructions into mobile device  102  (e.g., via a keypad and/or touch screen), and/or otherwise manipulate mobile device  102  and its associated components. User interface  105  may also permit mobile device  102  to communicate data to a user, e.g., by way of a display device. 
     Microphone  106  may be housed at least partially within enclosure  101 , may be communicatively coupled to controller  103 , and may comprise any system, device, or apparatus configured to convert sound incident at microphone  106  to an electrical signal that may be processed by controller  103 , wherein such sound is converted to an electrical signal using a diaphragm or membrane having an electrical capacitance that varies as based on sonic vibrations received at the diaphragm or membrane. Microphone  106  may include an electrostatic microphone, a condenser microphone, an electret microphone, a microelectromechanical systems (MEMS) microphone, or any other suitable capacitive microphone. 
     Radio transmitter/receiver  108  may be housed within enclosure  101 , may be communicatively coupled to controller  103 , and may include any system, device, or apparatus configured to, with the aid of an antenna, generate and transmit radio-frequency signals as well as receive radio-frequency signals and convert the information carried by such received signals into a form usable by controller  103 . Radio transmitter/receiver  108  may be configured to transmit and/or receive various types of radio-frequency signals, including without limitation, cellular communications (e.g., 2G, 3G, 4G, LTE, etc.), short-range wireless communications (e.g., BLUETOOTH), commercial radio signals, television signals, satellite radio signals (e.g., GPS), Wireless Fidelity, etc. 
     A mechanical transducer  110  may be housed at least partially within enclosure  101  or may be external to enclosure  101 , may be communicatively coupled to controller  103  (e.g., via a respective amplifier  112 ), and may comprise any system, device, or apparatus made with one or more materials configured to generate electric potential or voltage when mechanical strain is applied to mechanical transducer  110 , or conversely to undergo mechanical displacement or change in size or shape (e.g., change dimensions along a particular plane) when a voltage is applied to mechanical transducer  110 . In some embodiments, a mechanical transducer may comprise a piezoelectric transducer made with one or more materials configured to, in accordance with the piezoelectric effect, generate electric potential or voltage when mechanical strain is applied to mechanical transducer  110 , or conversely to undergo mechanical displacement or change in size or shape (e.g., change dimensions along a particular plane) when a voltage is applied to mechanical transducer  110 . 
     In some embodiments, mechanical transducer  110  may comprise a structure similar to a dynamic loudspeaker, which employs a lightweight diaphragm mechanically coupled to a rigid frame via a flexible suspension that constrains a voice coil to move axially through a cylindrical magnetic gap. When an electrical signal is applied to the voice coil, a magnetic field is created by the electric current in the voice coil, making it a variable electromagnet. The coil and the driver&#39;s magnetic system interact, generating a mechanical force that causes the coil (and thus, the attached cone) to move back and forth, thereby reproducing sound under the control of the applied electrical signal coming from an amplifier. 
     Although specific example components are depicted above in  FIG. 1A  as being integral to mobile device  102  (e.g., controller  103 , memory  104 , user interface  105 , microphone  106 , radio transmitter/receiver  108 , mechanical transducers  110 , amplifiers  112 ), a mobile device  102  in accordance with this disclosure may comprise one or more components not specifically enumerated above. 
       FIG. 1B  illustrates an exploded perspective view of selected components of example mobile device  102 , in accordance with embodiments of the present disclosure. As shown in  FIG. 1B , enclosure  101  may include a main body  120 , a mechanical transducer assembly  114 , and a cover assembly  130 , such that when constructed, mechanical transducer assembly  114  is interfaced between main body  120  and cover assembly  130 . Main body  120  may house a number of electronics, including controller  103 , memory  104 , radio transmitter/receiver  108 , and/or microphone  106 , as well as a display (e.g., a liquid crystal display) of user interface  105 . 
     Mechanical transducer assembly  114  may comprise a frame  124  configured to hold and provide mechanical structure for one or more mechanical transducers  110  (which may be coupled to controller  103 ) and transparent film  128 . 
     Cover assembly  130  may comprise a frame  132  configured to hold and provide mechanical structure for transparent cover  134 . Transparent cover  134  may be made from any suitable material (e.g., ceramic) that allows visibility through transparent cover  134 , protection of mechanical transducer  110  and display  122 , and/or user interaction with display  122 . 
     Although  FIG. 1B  illustrates mechanical transducer assembly  114  being situated between cover assembly  130  and display  122 , in some embodiments, mechanical transducer assembly  114  may reside “behind” display  122 , such that display  122  is situated between cover assembly  130  and mechanical transducer assembly  114 . In addition, although  FIG. 1B  illustrates mechanical transducers  110  located at edges of mechanical transducer assembly  114  (and thus, at or near the edge of display  122 ), mechanical transducers  110  may be located at any suitable location below cover  134  and/or display  122 . For example,  FIG. 2A  illustrates a side elevation view of selected components of another embodiment of example mobile device  102 , in accordance with embodiments of the present disclosure, while  FIG. 2B  illustrates a top plan view of selected components of example mobile device  102 , in accordance with embodiments of the present disclosure; both  FIGS. 2A and 2B  show that mechanical transducers  110  may be located in any suitable location within mobile device  102 . 
     Although  FIGS. 1A-2B  depict certain numbers of mechanical transducers  110  (e.g., two mechanical transducers  110  in  FIGS. 1A and 1B  and three mechanical transducers  110  in  FIGS. 2A and 2B ), mobile device  102  may include any suitable number of mechanical transducers  110 . 
     Mechanical transducers, including piezoelectric transducers, are typically used to convert electric signals into mechanical force. Thus, when used in connection with display  122  and/or cover  134 , one or more mechanical transducers  110  may cause vibration on a surface of cover  134 , which in turn may produce pressure waves in air, generating human-audible sound. Accordingly, in operation of mobile device  102 , one or more mechanical transducers  110  may be driven by respective amplifiers  112  under the control of controller  103  in order to generate acoustical sound by vibrating the surface of cover  134 . 
     However, mechanical transducers, including piezoelectric transducers and coil-based dynamic transducers, may also function in reverse, such that mechanical force applied to a mechanical transducer  110  may result in the mechanical transducer generating an electrical signal indicative of the mechanical force applied. 
     Accordingly, in accordance with the systems and methods disclosed herein, mobile device  102  may comprise a plurality of mechanical transducers  110  driving a common screen (e.g., display  122 , cover  134 ), wherein one or more of the mechanical transducers  110  may drive the common screen in order to generate human-audible sound, and one or more of other mechanical transducers  110  may be used as sensors, converting a measure of mechanical energy local to such sensor mechanical transducers  110 —which may be indicative of an undesired displacement or mechanical vibration of the screen—into electrical signals (e.g., voltages) indicative of the undesired displacement or mechanical vibration of the screen. Further, the electrical signals produced by a mechanical transducer  110  acting as a sensor may be received by controller  103 , which may implement a control circuit to inject a cancelling signal (e.g., scaled amounts of drive current from a synthesized high-impedance source) to mechanically control the mechanical transducer  110  acting as a sensor to cancel out the undesired displacement or mechanical vibration of the screen, resulting in a reduced mechanical (and hence reduced acoustic) output in a local area specific to the mechanical transducer  110  acting as a sensor. 
     While only two mechanical transducers  110  may be necessary to implement such a system (e.g., one mechanical transducer  110  driving a screen at one location and another mechanical transducer sensing and cancelling in another location of the screen), the use of multiple transducers  110  may lead to greater cancellation and localized control of cancellation, while also enabling different “active” acoustic areas on mobile device  102  in applications in which such flexibility is desirable. 
       FIG. 3  illustrates a circuit diagram of an example amplifier  112 A and mechanical transducer  110 A for generating acoustical sound via a screen surface, in accordance with embodiments of the present disclosure. As shown in  FIG. 3 , an amplifier  112 A, which may be configured as a voltage-controlled voltage source, may receive an input signal and generate an appropriate output signal based on the input signal in order to drive mechanical transducer  110 A directly, or in some cases such as when a Class D or switching amplifier is used, via a matching/filter network. In turn, mechanical transducer  110 A may be mechanically coupled to a screen (e.g., display  122  and/or cover  134 ), and may cause mechanical movement/vibration of such screen in order to generate acoustical sound. 
       FIG. 4  illustrates a circuit diagram of an example amplifier  112 B and mechanical transducer  110 B for actively sensing mechanical energy (e.g., at a screen surface) and correcting for the sensed mechanical energy with an opposing drive in order to establish a localized acoustic null on the screen surface proximate to mechanical transducer  110 B, in accordance with embodiments of the present disclosure. In operation, mechanical transducer  110 B may generate a voltage V SENSE  across its terminals in response to mechanical displacement/vibration of mechanical transducer  110 B. Voltage V SENSE  may be sensed by a control circuit  400  (e.g., implemented by controller  103 ) which may compare voltage V SENSE  to a reference voltage V REF  in order to generate an error voltage V ERR  Amplifier  112 B, which may comprise a voltage-controlled current source, may generate a corrective current I CORR  as a function of error voltage V ERR  in order to generate an acoustic null on the screen surface proximate to mechanical transducer  110 B. 
       FIG. 5  illustrates a circuit diagram of an example amplifier  112 C and a multi-layer mechanical transducer  110 C for actively sensing mechanical energy (e.g., at a screen surface) and correcting for the sensed mechanical energy with an opposing drive in order to establish a localized acoustic null on the screen surface proximate to mechanical transducer  110 C, in accordance with embodiments of the present disclosure. As shown in  FIG. 5 , mechanical transducer  110 C may comprise a three-terminal device, such that one layer of mechanical transducer  110 C may be used for driving mechanical movement while another layer of mechanical transducer  110 C may be used for sensing mechanical movement. In operation, mechanical transducer  110 C may generate a voltage V SENSE  as shown in  FIG. 5  in response to mechanical displacement/vibration of mechanical transducer  110 C. Voltage V SENSE  may be sensed by a control circuit  500  (e.g., implemented by controller  103 ) which may compare voltage V SENSE  to a reference voltage V REF  in order to generate an error voltage V ERR . Amplifier  112 C, which may comprise a voltage-controlled voltage source, may generate a corrective voltage V CORR  as a function of error voltage V ERR  in order to generate an acoustic null on the screen surface proximate to mechanical transducer  110 C. 
     As used herein, when two or more elements are referred to as “coupled” to one another, such term indicates that such two or more elements are in electronic communication or mechanical communication, as applicable, whether connected indirectly or directly, with or without intervening elements. 
     This disclosure encompasses all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Similarly, where appropriate, the appended claims encompass all changes, substitutions, variations, alterations, and modifications to the example embodiments herein that a person having ordinary skill in the art would comprehend. Moreover, reference in the appended claims to an apparatus or system or a component of an apparatus or system being adapted to, arranged to, capable of, configured to, enabled to, operable to, or operative to perform a particular function encompasses that apparatus, system, or component, whether or not it or that particular function is activated, turned on, or unlocked, as long as that apparatus, system, or component is so adapted, arranged, capable, configured, enabled, operable, or operative. Accordingly, modifications, additions, or omissions may be made to the systems, apparatuses, and methods described herein without departing from the scope of the disclosure. For example, the components of the systems and apparatuses may be integrated or separated. Moreover, the operations of the systems and apparatuses disclosed herein may be performed by more, fewer, or other components and the methods described may include more, fewer, or other steps. Additionally, steps may be performed in any suitable order. As used in this document, “each” refers to each member of a set or each member of a subset of a set. 
     Although exemplary embodiments are illustrated in the figures and described below, the principles of the present disclosure may be implemented using any number of techniques, whether currently known or not. The present disclosure should in no way be limited to the exemplary implementations and techniques illustrated in the drawings and described above. 
     Unless otherwise specifically noted, articles depicted in the drawings are not necessarily drawn to scale. 
     All examples and conditional language recited herein are intended for pedagogical objects to aid the reader in understanding the disclosure and the concepts contributed by the inventor to furthering the art, and are construed as being without limitation to such specifically recited examples and conditions. Although embodiments of the present disclosure have been described in detail, it should be understood that various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the disclosure. 
     Although specific advantages have been enumerated above, various embodiments may include some, none, or all of the enumerated advantages. Additionally, other technical advantages may become readily apparent to one of ordinary skill in the art after review of the foregoing figures and description. 
     To aid the Patent Office and any readers of any patent issued on this application in interpreting the claims appended hereto, applicants wish to note that they do not intend any of the appended claims or claim elements to invoke 35 U.S.C. § 112(f) unless the words “means for” or “step for” are explicitly used in the particular claim.