PATENT DOCUMENT

Publication Number: US-10680161-B1
Application Number: US-201715785175-A
Country: US
Kind Code: B1

Title: Electronic Devices with Piezoelectric Ink

Abstract:
An electronic device may have input devices and/or output devices based on piezoelectric components. Piezoelectric components may include piezoelectric ink in which particles of piezoelectric material are dispersed in a binder. The piezoelectric ink may be printed or otherwise deposited onto a substrate to form piezoelectric ink traces. The piezoelectric ink traces may be deposited on flexible substrates such as elastic speaker diaphragms or flexible fabric layers. The piezoelectric traces may be part of a key in a keyboard or a stand-alone button. In arrangements where the piezoelectric trace forms part of a key in a keyboard, the piezoelectric trace may be coupled to a grid of horizontal and vertical signal lines. The signal lines may convey key press data from the piezoelectric trace to control circuitry and/or may supply control signals from the control circuitry to the piezoelectric trace to produce haptic output.

Claims:
What is claimed is: 
     
       1. An electronic device, comprising:
 a substrate; 
 a piezoelectric trace on the substrate, wherein the piezoelectric trace comprises piezoelectric particles dispersed in a binder; 
 control circuitry; and 
 a conductive signal path that conveys signals between the piezoelectric trace and the control circuitry. 
 
     
     
       2. The electronic device defined in  claim 1  wherein the piezoelectric trace has a serpentine shape. 
     
     
       3. The electronic device defined in  claim 1  further comprising an additional piezoelectric trace on the substrate, wherein the control circuitry supplies control signals to the piezoelectric trace and the additional piezoelectric trace to cause the piezoelectric trace and the additional piezoelectric trace to vibrate. 
     
     
       4. The electronic device defined in  claim 3  wherein the control signal supplied to the piezoelectric trace has a first waveform and the control signal applied to additional piezoelectric trace has a second waveform, and wherein the second waveform is 90 degrees out of phase with the first waveform such that vibration of the piezoelectric trace and the additional piezoelectric trace forms a surface wave. 
     
     
       5. The electronic device defined in  claim 4  wherein the surface wave has a frequency in the ultrasonic range. 
     
     
       6. The electronic device defined in  claim 1  wherein the substrate comprises a speaker diaphragm. 
     
     
       7. The electronic device defined in  claim 1  wherein the substrate comprises a fabric layer. 
     
     
       8. The electronic device defined in  claim 1  further comprising a movable key member, wherein the piezoelectric trace overlaps the movable key member. 
     
     
       9. The electronic device defined in  claim 1  further comprising an array of keys and wherein the piezoelectric trace overlaps one of the keys. 
     
     
       10. The electronic device defined in  claim 9  wherein the control circuitry applies a voltage to the piezoelectric trace to provide haptic output. 
     
     
       11. The electronic device defined in  claim 9  wherein the control circuitry gathers key press data from the piezoelectric trace. 
     
     
       12. The electronic device defined in  claim 1  wherein the piezoelectric particles comprise lead zirconate titanate. 
     
     
       13. The electronic device defined in  claim 1  wherein the binder comprises material selected from the group consisting of: silicone and metal oxide. 
     
     
       14. A keyboard, comprising:
 an array of keys; 
 piezoelectric ink traces that each overlap a respective one of the keys; 
 control circuitry; and 
 a grid of signal lines coupled to the piezoelectric ink traces, wherein the grid of signal lines conveys signals between the piezoelectric ink traces and the control circuitry. 
 
     
     
       15. The keyboard defined in  claim 14  wherein the grid of signal lines comprises horizontal signal lines and vertical signal lines, wherein each piezoelectric ink trace comprises first and second opposing ends coupled respectively to first and second terminals, wherein the first terminal is coupled to one of the vertical signal lines and the second terminal is coupled to one of the horizontal signal lines. 
     
     
       16. The keyboard defined in  claim 14  wherein each key comprises a movable key member. 
     
     
       17. The keyboard defined in  claim 14  further comprising a fabric layer, wherein the piezoelectric traces are formed on the fabric layer. 
     
     
       18. Apparatus, comprising:
 a flexible substrate; 
 piezoelectric material on the flexible substrate, wherein the piezoelectric material comprises piezoelectric particles dispersed in a binder; and 
 control circuitry that supplies haptic output by applying a voltage to the piezoelectric material. 
 
     
     
       19. The apparatus defined in  claim 18  wherein the control circuitry gathers touch input using the piezoelectric material. 
     
     
       20. The apparatus defined in  claim 18  wherein the piezoelectric material has a serpentine shape.

Description:
This application claims the benefit of provisional patent application No. 62/478,512, filed Mar. 29, 2017, which is hereby incorporated by reference herein in its entirety. 
    
    
     FIELD 
     This relates generally to electronic devices and, more particularly, to electronic devices with piezoelectric components. 
     BACKGROUND 
     Electronic devices often include input-output devices for gathering input and providing output. Input-output devices are sometimes formed from piezoelectric materials. For example, haptic output devices such as vibrators may use piezoelectric materials. 
     It can be challenging to incorporate conventional piezoelectric components into an electronic device. For example, it may be difficult to mount piezoelectric ceramic wafers to flexible substrates or to achieve the desired output from the piezoelectric material. 
     SUMMARY 
     An electronic device may have input devices and/or output devices based on piezoelectric components. Piezoelectric components may include piezoelectric ink in which particles of piezoelectric material are dispersed in a binder. The piezoelectric particles may be lead zirconate titanate or other suitable piezoelectric material. The binder may be formed from a metal oxide, a polymer material such as silicone, or other suitable material. 
     The piezoelectric ink may be printed or otherwise deposited onto a substrate to form piezoelectric ink traces. The fluid or paste-like nature of the piezoelectric ink may allow the piezoelectric ink to be deposited on a variety of surfaces including flexible surfaces, curved surfaces, and surfaces with protrusions, recesses, or other surface features. 
     The piezoelectric ink traces may be deposited on a flexible membrane that forms a diaphragm for a speaker. Control circuitry may apply a voltage to the piezoelectric traces to cause the piezoelectric traces to vibrate the flexible membrane to produce sound. 
     The piezoelectric traces may be part of a key in a keyboard or a stand-alone button. Control circuitry may supply haptic output from the key using the piezoelectric traces and/or may receive key press data that the piezoelectric traces produce in response to an applied force or touch. 
     In arrangements where the piezoelectric trace forms part of a key in a keyboard, the piezoelectric trace may be coupled to a grid of horizontal and vertical signal lines. Each trace may have first and second opposing ends coupled to first and second terminals. The first terminal may be coupled to one of the horizontal signal lines and the second terminal may be coupled to one of the vertical signal lines. The signal lines may convey key press data from the piezoelectric trace to control circuitry and/or may supply control signals from the control circuitry to the piezoelectric trace to produce haptic output. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic diagram of an illustrative electronic device with piezoelectric components in accordance with an embodiment. 
         FIG. 2  is a perspective view of an illustrative electronic device with piezoelectric components in accordance with an embodiment. 
         FIG. 3  is a top view of illustrative fabric in accordance with an embodiment. 
         FIG. 4  is a diagram of an illustrative piezoelectric component that converts electrical energy into mechanical energy in accordance with an embodiment. 
         FIG. 5  is a diagram of an illustrative piezoelectric component that converts mechanical energy into electrical energy in accordance with an embodiment. 
         FIG. 6  is a side view of an illustrative piezoelectric component formed from printed piezoelectric ink in accordance with an embodiment. 
         FIG. 7  is a top view of an illustrative piezoelectric component formed from a printed trace of piezoelectric ink on a substrate in accordance with an embodiment. 
         FIG. 8  is an enlarged view of a portion of the piezoelectric component of  FIG. 7  in accordance with an embodiment. 
         FIG. 9  is a perspective view of an illustrative piezoelectric component having piezoelectric ink traces that form a motor in accordance with an embodiment. 
         FIG. 10  is a cross-sectional side view of an illustrative speaker having a piezoelectric component in accordance with an embodiment. 
         FIG. 11  is a cross-sectional side view of an illustrative key having a piezoelectric component that overlaps a movable key member in accordance with an embodiment. 
         FIG. 12  is a cross-sectional side view of an illustrative key having a piezoelectric component that detects key presses and/or that provides haptic output in accordance with an embodiment. 
         FIG. 13  is a cross-sectional side view of an illustrative keyboard having an array of keys with piezoelectric components in accordance with an embodiment. 
         FIG. 14  is a top view of an illustrative keyboard having an array of piezoelectric components that produce haptic output and/or receive user input in accordance with an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Electronic devices may be provided with input-output devices. The input-output devices may include components that gather input from a user such as touch sensors, buttons, force sensors, force-sensitive touch sensors, microphones, and other input gathering components. The input-output devices may also include components that provide output to a user such as speakers that provide audio output and haptic devices that provide haptic output (e.g., tactile output in the form of vibrations that are picked up by a user&#39;s fingers). 
     Input-output devices may include piezoelectric components. The piezoelectric components may include piezoelectric fluid or ink in which piezoelectric particles are dispersed in a binder. The piezoelectric ink may be deposited on a substrate. Illustrative components that may include piezoelectric inks include audio components such as speakers and microphones, buttons, touch sensors, force sensors, ultrasonic sensors, other sensors, ultrasonic motors, other motors, actuators, latches, other components, or components that implement the functionality of two more of these components. 
     A schematic diagram of an illustrative electronic device of the type that may include piezoelectric components such as piezoelectric components based on piezoelectric ink is shown in  FIG. 1 . Electronic device  10  of  FIG. 1  may be an electronic device such as a laptop computer, a computer monitor containing an embedded computer, a tablet computer, a cellular telephone, a media player, or other handheld or portable electronic device, a smaller device such as a wristwatch device, a pendant device, a headphone or earpiece device, a device embedded in eyeglasses or other equipment worn on a user&#39;s head, or other wearable or miniature device, a television, a computer display that does not contain an embedded computer, a gaming device, a navigation device, an embedded system such as a system in which electronic device  10  is mounted in a kiosk, in an automobile, airplane, or other vehicle, other electronic equipment, or equipment that implements the functionality of two or more of these devices. If desired, electronic device  10  may be a removable external case for electronic equipment or other device accessory, may be a strap, may be a wrist band or head band, may be a removable cover for a device, may be a case or bag that has straps or that has other structures to receive and carry electronic equipment and other items, may be a necklace or arm band, may be a wallet, sleeve, pocket, or other structure into which electronic equipment or other items may be inserted, may be part of a chair, sofa, or other seating (e.g., cushions or other seating structures), may be part of an item of clothing or other wearable item (e.g., a hat, belt, wrist band, headband, shirt, pants, shoes, etc.), may be a keyboard, or may be any other suitable device that includes circuitry. 
     As shown in  FIG. 1 , electronic device  10  may have control circuitry  12 . Control circuitry  12  may include storage and processing circuitry for supporting the operation of device  10 . The storage and processing circuitry may include storage such as hard disk drive storage, nonvolatile memory (e.g., flash memory or other electrically-programmable-read-only memory configured to form a solid state drive), volatile memory (e.g., static or dynamic random-access-memory), etc. Processing circuitry in control circuitry  12  may be used to control the operation of device  10 . The processing circuitry may be based on one or more microprocessors, microcontrollers, digital signal processors, baseband processors, power management units, audio chips, application specific integrated circuits, etc. 
     Input-output circuitry in device  10  such as input-output devices  14  may be used to allow data to be supplied to device  10  and to allow data to be provided from device  10  to external devices. Input-output devices  14  may include buttons, joysticks, scrolling wheels, touch pads, key pads, keyboards, microphones, speakers, tone generators, vibrators, cameras, sensors, light-emitting diodes and other status indicators, displays, data ports, etc. Input-output devices  14  may include piezoelectric components  20  such as components based on piezoelectric materials. Piezoelectric materials exhibit the piezoelectric effect by generating voltages in response to applied force. Piezoelectric materials also exhibit the “reverse” piezoelectric effect by moving in response to an applied electric field. As a result, piezoelectric materials can be used for both sensing and actuation applications. Piezoelectric components  20  may include piezoelectric ink in which particles of piezoelectric material are dispersed in a binder and printed or otherwise deposited on a substrate. 
     Piezoelectric components  20  may include audio components such as speakers and microphones, buttons, touch sensors, force sensors, ultrasonic sensors, other sensors, ultrasonic motors, other actuators, latches, other components, or components that implement the functionality of two more of these components. 
     Control circuitry  12  may be used to run software on device  10  such as operating system code and applications. During operation of device  10 , the software running on control circuitry  12  may use input-output devices  14  to gather user input (e.g., key press input or other input from a keyboard, button press input from a button on a fabric wrist band or other fabric item, or other input from input-output devices  14 ) and to supply the user with output using input-output devices  14 . Device  10  may, for example, supply a user with output using piezoelectric components  20  (e.g., haptic feedback to inform a user that input on a key in a keyboard, a button on a watch band, or other input device has been received, audio feedback, or other suitable output). Device  10  may also receive input using piezoelectric components  20  (e.g., audio input, touch input, force input, etc.). In some configurations, piezoelectric components  20  may be used for sensing or actuation that is not necessarily related to input from a user or output for a user. For example, piezoelectric components  20  may be used to actuate a latch (e.g., to attach or detach two parts of device  10 ), may be used as a motor for actuating a lens in a camera, etc. Piezoelectric components  20  may, if desired, be used to provide vibrating alerts (haptic alerts) and other haptic output (i.e., haptic output that is not necessarily directly related to confirming a key press or button press). In general, piezoelectric components  20  be used for forming any suitable actuators and/or sensors. 
     A perspective view of an illustrative electronic device that may include piezoelectric components is shown in  FIG. 2 . As shown in  FIG. 2 , electronic device  10  may include strap  18  and electronic device housing  16 . In the illustrative example of  FIG. 2 , strap  18  is attached to housing  16  and may, for example, be used to attach electronic device  10  to some part of a user&#39;s body. For example, strap  18  may form a wrist band, an arm band, a head band, a waist band, or other article that can be secured against a user&#39;s body and that can support or hold electronic device  10  in place (e.g., against a user&#39;s skin). The arrangement of  FIG. 2  is, however, merely illustrative. In general, housing  16  and strap  18  may be integrated with or attached to one another in any suitable fashion. 
     In the example of  FIG. 2 , device  10  includes display  24 . Display  24  has been mounted in housing  16 . Housing  16 , which may sometimes be referred to as an enclosure or case, may be formed of plastic, glass, ceramics, fiber composites, metal (e.g., stainless steel, aluminum, etc.), other suitable materials, or a combination of any two or more of these materials. Housing  16  may be formed using a unibody configuration in which some or all of housing  16  is machined or molded as a single structure or may be formed using multiple structures (e.g., an internal frame structure, one or more structures that form exterior housing surfaces, etc.). 
     Display  24  may be a touch screen display that incorporates a layer of conductive capacitive touch sensor electrodes or other touch sensor components (e.g., resistive touch sensor components, acoustic touch sensor components, force-based touch sensor components, light-based touch sensor components, etc.) or may be a display that is not touch-sensitive. Capacitive touch screen electrodes may be formed from an array of indium tin oxide pads or other transparent conductive structures. 
     Display  24  may include an array of pixels formed from liquid crystal display (LCD) components, an array of electrophoretic pixels, an array of plasma display pixels, an array of organic light-emitting diode pixels, an array of electrowetting pixels, or pixels based on other display technologies. 
     In the illustrative example of  FIG. 2 , piezoelectric component  20  may be formed on or integrated with strap  18 . Electrical path  26  may be used to convey signals between piezoelectric component  20  and components in housing  16  such as component  80 . Component  80  may, for example, be a voltage source that supplies a voltage to piezoelectric component  20  and/or may be an electrical load that receives electrical current from piezoelectric component  20  over path  26  in response to an applied force on piezoelectric component  20 . 
     Component  80  (e.g., an electrical supply or load) may be mounted in housing  16  of electronic device  10  and may be coupled to path  26  in strap  18 . In some arrangements, path  26  and component  80  may be detachable from one another so that strap  18  can be detached from housing  16 . In other arrangements, path  26  may be permanently coupled to component  80  in housing  16 . The arrangement of  FIG. 2  is merely illustrative, however. If desired, component  80  may be mounted to or incorporated into strap  18 , or piezoelectric component  20  and path  26  may be mounted in housing  16 . 
     Device  10  may include fabric. Fabric may be used to form a housing structure, part of a strap or band such as band  18  of  FIG. 2 , a cover for a keyboard, or other structures in device  10 . In arrangements of the type shown in  FIG. 2 , fabric may be used to form all or a portion of strap  18 . Fabric may be knitted, braided, woven, or otherwise formed from intertwined fibers. As an example, the fabric for device  10  may include woven fabric such as illustrative woven fabric  74  of  FIG. 3 . 
     As shown in  FIG. 3 , fabric  74  may include strands of material such as warp strands  76  and perpendicular strands of material such as weft strands  78 . Fabric  74  may have a plain weave, a basket weave, may be a three-dimensional fabric (e.g., a spacer fabric), or may have other suitable fabric constructions. Strands  76  and  78  may include insulating strands and/or conductive strands. Conductive strands may be formed from metal wires, metal wires coated with polymer, metal coatings on insulating strands of material such as glass or polymer strands, or other suitable conductive structures. Insulating strands may be formed from polymer, other dielectric, multiple dielectric layers, or other suitable insulating structures. Strands of material in fabric  74  may be monofilaments or may be multifilament yarns. Fabric  74  may include exclusively insulating strands, may include exclusively conductive strands, or may include a mixture of insulating and conductive strands. For example, fabric  74  may include insulating strands and conductive strands and the conductive strands may be used in carrying signals associated with input-output devices  14  (e.g., currents for controlling piezoelectric devices  20 , sensor signals from piezoelectric devices  20 , etc.). 
     Diagrams of illustrative piezoelectric components that may be used in electronic device  10  are shown in  FIGS. 4 and 5 . In the example of  FIG. 4 , piezoelectric component  20  exhibits the inverse piezoelectric effect to convert electrical energy into mechanical energy. Piezoelectric component  20  may include a piezoelectric material such as piezoelectric material  28 . Piezoelectric material  28  may have a net polarization (sometimes referred to as a poling voltage) as a result of being poled (e.g., a process during which piezoelectric material is exposed to a strong magnetic field to align domains, or groups of dipoles, in the material). Examples of materials that may be used to form piezoelectric material  28  include synthetic ceramics such as lead zirconate titanate (PZT), naturally occurring crystals such as quartz, synthetic crystals such as langasite, polymer-based piezoelectric materials such as Polyvinylidene fluoride, lead-free piezoceramics such as sodium potassium niobate, piezoelectric nanotubes such as boron-nitride nanotubes or composite carbon nanotubes, other suitable piezoelectric materials, or a combination of any two or more of these materials. Piezoelectric material  28  may be formed from a single solid piezoelectric substance or may be formed from a piezoelectric fluid or paste in which piezoelectric particles are dispersed in a binder that can be printed or otherwise deposited onto a surface. 
     An electrical supply such as electrical supply  30  (e.g., a voltage source) may supply a current (e.g., an alternating current or a direct current) to electrodes  82  and  84 . The resulting voltage across piezoelectric material  28  causes piezoelectric material  28  to either elongate (as indicated by arrows  34 ) or compress (as indicated by arrows  36 ), depending on the polarity of the applied voltage. The mechanical output from piezoelectric material  28  may be proportional to the voltage applied to material  28 . When supply  30  applies an alternating current to piezoelectric material  28 , piezoelectric material  28  will lengthen and shorten cyclically at the frequency of the applied voltage, resulting in a mechanical vibration. This type of mechanical vibration may be used to form a motor (e.g., an ultrasonic motor or other suitable motor), a sound generating device (e.g., a speaker), a haptic output device (e.g., a vibrator), or other suitable device. 
     In the example of  FIG. 5 , piezoelectric component  20  exhibits the piezoelectric effect to convert mechanical energy into electrical energy. When a tension force (as indicated by arrows  34 ) or a compressive force (as indicated by arrows  36 ) is applied to piezoelectric material  28 , a voltage is generated across piezoelectric material  28 , having a polarity that is either the same as or opposite to the poling voltage of piezoelectric material  28 , depending on the direction of compression or tension relative to the poling voltage. The resulting voltage across electrodes  82  and  84  may supply a current to an electrical load such as electrical load  32 . The electrical signal produced by piezoelectric material  28  may be proportional to the amount of compressive or tension force applied to material  28 . In this way, piezoelectric component  20  of  FIG. 5  may be used as a sensor (e.g., an ultrasonic sensor, a microphone, a force sensor, a touch sensor, or other suitable sensor). 
     If desired, the same piezoelectric component may be used to exhibit both the piezoelectric effect and the reverse piezoelectric effect (e.g., may be coupled to both an electrical source and an electrical load). The diagrams of  FIGS. 4 and 5  are merely illustrative of the two phenomena that piezoelectric component  20  may be capable of exhibiting. 
     Piezoelectric material  28  in components  20  of device  10  may be formed from a piezoelectric fluid or ink that can be printed onto a substrate or other support surface.  FIG. 6  is a diagram showing how piezoelectric ink  28  may be printed onto the surface of support  38 . Support  38  may be a planar substrate, a curved substrate, a fabric substrate, an elastic diaphragm or other flexible substrate, or may be any other suitable support structure. Ink-jet dispenser  86  may be controlled using computer-controlled positioner  88 . When moved in direction  90 , dispenser  86  may deposit piezoelectric ink  28  onto support  38 , thereby forming a desired shape and pattern of piezoelectric material  28  on support  38 . Piezoelectric ink (e.g., binder material that contains piezoelectric particles) may be applied to a support structure using ink-jet printing, screen printing, pad printing, spraying, dipping, dripping, painting, or other suitable deposition techniques. 
     The example of  FIG. 6  in which piezoelectric material  28  is deposited on support  38  is merely illustrative. Examples of other equipment that may be used to form or otherwise process piezoelectric material  28  include extrusion equipment, molding equipment (e.g., injection molding equipment, compression molding equipment, or other suitable molding equipment), physical vapor deposition equipment, chemical vapor deposition equipment, electrochemical deposition equipment (e.g., tools for electroless chemical deposition and/or electroplating), etching equipment, equipment for dispensing and curing liquid polymer (e.g., liquid polymer containing magnetic material), soldering equipment, cutting tools, machining equipment, equipment for forming welds, three-dimensional printing equipment (e.g., three-dimensional printing tools or other equipment that applies light or other energy to sinter, cure, ablate, and/or otherwise adjust the properties of material associated with a 3D printing process), etc. 
       FIG. 7  is a top view of an illustrative piezoelectric component  20  having piezoelectric ink  28 . Piezoelectric ink  28  (sometimes referred to as a fluid, a colloidal mixture, or paste) may be deposited on support  38  in any suitable pattern (e.g., using deposition equipment of the type shown in  FIG. 6 ). In the example of  FIG. 7 , piezoelectric ink  28  has a serpentine pattern on surface  38 . This is, however, merely illustrative. If desired, piezoelectric ink  28  may be formed in a spiral pattern, a zigzag pattern, a pattern of parallel lines, or any other suitable pattern. Ink  28  may be deposited to form one or more individual traces (as in the example of  FIG. 7 ) or ink  28  may be deposited as a continuous layer covering a more substantial surface area on support  38 . Ink  28  may be deposited over planar surfaces (e.g., may extend across a two-dimensional space) and/or may be deposited over surfaces with contours, curves, protrusions, recesses, steps, or other three-dimensional surface features. 
     Piezoelectric ink  28  may be coupled to conductive paths such as conductive signal paths  64 . Conductive signal paths  64  may be metal traces on substrate  38  may be wires, may be flexible printed circuits, or may be other suitable conductive paths that convey electrical signals between piezoelectric ink  28  and control circuitry  12  ( FIG. 1 ). Conductive paths  64  may be used to apply a voltage to piezoelectric ink  28  to cause piezoelectric ink  28  (and, if desired, support  38 ) to move and/or may be used to transmit electrical signals from piezoelectric ink  28  that are produced in response to a force applied to piezoelectric ink  28 . If desired, electrodes may be located above and below ink  28  so that substrate  38  and ink  28  are sandwiched between first and second conductive layers. The conductive layers may be used to apply an electric field to ink  28  to produce mechanical energy and/or may be used to transmit electrical signals from ink  28  in response to a force applied to ink  28 . 
       FIG. 8  is an enlarged view of region  40  of  FIG. 7  illustrating the composition of piezoelectric ink  28 . As shown in  FIG. 8 , piezoelectric ink  28  may include piezoelectric particles  42 . Examples of materials that may be used to form piezoelectric particles  42  include synthetic ceramics such as lead zirconate titanate (PZT), naturally occurring crystals such as quartz, synthetic crystals such as langasite, polymer-based piezoelectric materials such as Polyvinylidene fluoride, lead-free piezoceramics such as sodium potassium niobate, piezoelectric nanotubes such as boron-nitride nanotubes or composite carbon nanotubes, other suitable piezoelectric materials, or a combination of any two or more of these materials. A binder such as binder  40  (sometimes referred to as a matrix or supporting material) may be used to support piezoelectric particles  42  (i.e., piezoelectric particles  42  may be embedded within binder  40 ). Examples of materials that may be used to form binder  40  include metal oxides and polymers such as silicones, polyamides (e.g., nylon 6, nylon 12, etc.), polyphenylene sulfide (PPS), and other suitable polymers. Other materials may be used, if desired. 
       FIG. 9  shows an illustrative piezoelectric component  20  in which piezoelectric ink  28  forms multiple traces on support  38  such as piezoelectric ink trace  28 - 1  and piezoelectric ink trace  28 - 2 . If desired, piezoelectric ink traces  28 - 1  and  28 - 2  may have different properties. For example, traces  28 - 1  and  28 - 2  may have different patterns, may have different thicknesses, may have piezoelectric particles  42  formed from different materials, in different concentrations, in different shapes, etc., and/or may be driven at different voltages or frequencies. 
     Piezoelectric component  20  may be used to form an ultrasonic motor. For example, control circuitry  12  may apply a voltage to piezoelectric traces  28 - 1  and  28 - 2 , causing traces  28 - 1  and  28 - 2  to vibrate. The voltage applied to trace  28 - 1  may correspond to a first waveform (e.g., a cosine wave) and the voltage applied to trace  28 - 2  may correspond to a second waveform that is 90 degrees out of phase with the first waveform (e.g., a sine wave). This may cause traces  28 - 1  and  28 - 2  to vibrate out of phase with one another so that a surface wave is formed. In arrangements where component  20  forms part of an ultrasonic motor (e.g., a rotational ultrasonic motor or linear ultrasonic motor), the surface waves produced may have a frequency in the ultrasonic range. 
       FIG. 10  illustrates an arrangement in which piezoelectric component  20  forms part of an audio component such as a speaker. As shown in  FIG. 10 , speaker  48  may include a diaphragm such as flexible diaphragm  92  and a transducer  94  formed from piezoelectric ink  28 . Transducer  94  may receive electrical audio signal input from circuitry in device  10 , which in turn causes piezoelectric material  28  in transducer  94  to vibrate. The vibration of transducer  94  causes diaphragm  92  to vibrate at the same frequency, thereby producing audible sound. 
     Diaphragm  92  may be formed from a flexible material (e.g., a flexible polymer layer or other suitable flexible layer). Piezoelectric material  28  (e.g., an ink of the type described in connection with  FIG. 8 ) may be deposited directly on diaphragm  92  or may be deposited on a separate substrate that is then attached (e.g., via adhesive or other attachment mechanism) to diaphragm  92 . 
     A suspension structure such as suspension structure  46  may be used to attach portions of diaphragm  92  to a rigid support structure such as support structure  44 . Suspension structure  46  may help prevent speaker membrane  92  from moving laterally along the x-axis and/or the y-axis, but may allow free motion of speaker membrane  92  along the z-axis as speaker  48  produces sound. Suspension structure  46  may be formed from an elastomeric material, foam material, resin coated material, other suitable materials, or a combination of these materials. As shown in the example of  FIG. 10 , suspension structure  46  may form a pliant interface between speaker membrane  92  and support structure  44 . 
     If desired, piezoelectric ink  28  may be used in other types of input-output devices  14  in device  10  such as buttons (e.g., keys in a keyboard or stand-alone buttons). An illustrative key formed from a movable key member (e.g., a keyboard key or other button) is shown in  FIG. 11 . As shown in  FIG. 11 , key  50  may have movable key member  52  and flexible layer such as flexible outer layer  96  that overlaps key member  52 . Layer  96  may be a fabric layer, a flexible polymer layer, a layer of silicone, or other flexible member that forms an outer layer of key  50  in device  10 . Arrangements where layer  96  is a fabric layer are sometimes described herein as an illustrative example. Key  50  may include one or more piezoelectric components such as piezoelectric component  20 . Piezoelectric component  20  may include piezoelectric ink  28  formed on layer  96 , as shown in the example of  FIG. 11 . If desired, piezoelectric ink  28  may be formed on key member  52  instead of or in addition to being formed on layer  96  (e.g., piezoelectric material may be deposited on the surface of key member  52 , as indicated by material  28 ′ of  FIG. 11 ). 
     Keys such as key (button)  50  may include dome switches or other mechanically actuated input devices, as illustrated by dome switch  56  on substrate  54  in  FIG. 11 . In configurations in which key  50  includes a switch such as switch  56 , a user may press downwards on button  50  during a key press event. This moves button member  52  downwards and compresses dome switch  56 . Control circuitry  12  can monitor the state of dome switch  56  to detect key press events. Dome switch support structure  54  may be formed from a plastic support structure, a housing structure, a substrate such as a printed circuit having traces that route switch signals to control circuitry  12 , or other suitable support for dome switches such as dome switch  56 . If desired, dome switches and other mechanical switches may be omitted from keys such as key  50  and a user&#39;s input may be gathered using exclusively touch sensor input from a touch sensor in layer  96  and/or input from piezoelectric components  20 . Keys such as key  50  may be formed on any portion of device  10  that is accessible by a user&#39;s finger (e.g., the surface of a watch band, the surface of a keyboard, an exterior or interior portion of an item of clothing or bag, a surface of a console, the surface of a seat, the surface of an item of furniture, etc.). 
     Piezoelectric components in device  10  such as piezoelectric component  20  may be used for sensing (e.g., receiving input) and/or for actuation (e.g., providing output). For example, piezoelectric component  20  may be used to detect a force applied to fabric  96  over button  50  and/or may be used to provide haptic output in response to a user contacting or pressing button  50 . 
     During operation, a user may press on key  50  with the user&#39;s fingers. Dome switch  56  in each key  50 , piezoelectric component  20 , a touch sensor formed in fabric  96 , and/or other suitable input components associated with key  50  may be used to gather key press data. In response to detected key presses and/or in response to satisfaction of other criteria, control circuitry  12  may activate piezoelectric component  20  to provide haptic output. For example, a piezoelectric device  20  that overlaps a pressed key may be activated to provide a user with haptic feedback indicating that the key has been successfully pressed. 
       FIG. 12  is a cross-sectional side view of an example in which key  50  is formed without a moveable button member. With this type of arrangement, key press data may be gathered by piezoelectric component  20  in layer  96 , by a touch sensor formed in (or overlapping with) layer  96 ), and/or by other suitable input components associated with key  50 . In response to detected key presses and/or in response to satisfaction of other criteria, control circuitry  12  may activate piezoelectric component  20  to provide haptic output. For example, a piezoelectric device  20  that overlaps a pressed key may be activated to provide a user with haptic feedback indicating that the key has been successfully pressed. If desired, layer  96  may be sufficiently flexible that it bends towards lower housing structure  62  when pressed by a user&#39;s finger  60 , as shown in the example of  FIG. 12 , or layer  96  may be stiff so that it does not bend when pressed by a user&#39;s finger. 
       FIG. 13  is a cross-sectional side view of an illustrative electronic device having an array of keys  50 . In the example of  FIG. 13 , device  10  is a cover (or part of a cover) for a tablet computer or other electronic equipment. Device  10  may have housing structures formed from plastic, metal, glass, ceramic, carbon-fiber composites, fiberglass, and other fiber composites, fabric and other intertwined strands of material, and/or other materials. As an example, device  10  may have components that are mounted within a housing body formed from lower housing layer  66  and upper housing layer  96 . Lower housing layer  66  may be formed from plastic, plastic with embedded microfibers, or other materials. Upper housing layer  96  may be formed from fabric. 
     Device  10  may include a keyboard (e.g., a computer keyboard for an associated tablet computer, laptop computer, or other computing equipment). The keyboard may have an array of keys  50  that are formed in or covered by fabric layer  26 . Each key  50  may have a movable button member (e.g., of the type shown n  FIG. 11 ) or keys  50  may be free of movable button members, as shown in the example of  FIG. 13 . Fabric layer  96  may be supported by a support structure such as key web  70  (e.g., a plastic panel with rectangular openings  68  that overlap keys  50 ). Key web  70  may supply structural support for fabric layer  96  and may therefore form an internal frame for the upper housing wall of device  10 . Each key  50  may include a piezoelectric element such as piezoelectric component  20  for gathering key press data and/or for providing haptic output. 
     During operation, a user may press on key  50  with the user&#39;s fingers. Piezoelectric component  20 , a touch sensor formed in fabric  96 , and/or other suitable input components associated with key  50  may be used to gather key press data. In response to detected key presses and/or in response to satisfaction of other criteria, control circuitry  12  may activate piezoelectric component  20  to provide haptic output. For example, a piezoelectric device  20  that overlaps a pressed key may be activated to provide a user with haptic feedback indicating that the key has been successfully pressed. 
       FIG. 14  is a top view of a portion of an illustrative electronic device  10  have an array of keys with piezoelectric components. As shown in  FIG. 14 , each key  50  (e.g., a key of the type shown in  FIG. 11, 12 , or  13 ) of keyboard  98  has an associated piezoelectric component  20 . Keys  50  may each include an embossed key-shaped region of fabric  96 . If desired, fabric  96  may incorporate a touch sensor. For example, fabric  96  may include insulating strands (e.g., warp strands  76  and weft strands  78  of  FIG. 3 ) interspersed with conductive strands that form horizontal drive lines and vertical sense lines. 
     Piezoelectric elements  20  may each be formed from a trace or layer of piezoelectric material  28  (e.g., a piezoelectric ink of the type described in connection with  FIG. 8 ). Each segment of piezoelectric material  28  may have a first terminal  102  coupled to a vertical line  104  and a second terminal  106  coupled to a horizontal line  108  (e.g., using solder, welds, conductive adhesive, or other connections). Horizontal lines  108  and vertical lines  104  may be formed from metal traces on fabric  96 , metal traces on a printed circuit, conductive strands in fabric  96 , or conductive paths formed on any other suitable substrate and may be used as address lines for piezoelectric components  20  formed from respective piezoelectric material segments  28 . 
     Whenever a particular piezoelectric component  20  is to be activated, an electric field may be applied to material  28  of that piezoelectric component  20  by control circuitry  12  by applying a voltage across an appropriate set of lines (e.g., the horizontal line  108  coupled to the terminal  106  of that segment and a vertical line  104  coupled to the terminal  102  of that segment), resulting in haptic output from that piezoelectric component  20 . In arrangements where piezoelectric components  20  are used for sensing, mechanical input on piezoelectric components  20  (e.g., an applied force or touch from a user&#39;s finger) may result in a potential difference across terminals  102  and  106  that is conveyed to control circuitry  12  and processed as key press data. 
     The foregoing is merely illustrative and various modifications can be made to the described embodiments. The foregoing embodiments may be implemented individually or in any combination.

Metadata:
Filing Date: 20171016
Publication Date: 20200609
Grant Date: 20200609
Priority Date: 20170329
Inventors: BHARADWAJ, SHRAVAN
Assignee: APPLE INC
CPC Classifications: [{"code": "H01L41/0825", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R17/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L41/317", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L41/1876", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K17/9643", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L41/183", "inventive": true, "first": false, "tree": "[]"}, {"code": "H01L41/0475", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03K2217/96062", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K2217/96019", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K17/965", "inventive": true, "first": false, "tree": "[]"}, {"code": "H03K17/9643", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10N30/077", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10N30/077", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10N30/852", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10N30/8554", "inventive": false, "first": false, "tree": "[]"}, {"code": "H10N30/875", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R17/00", "inventive": true, "first": true, "tree": "[]"}, {"code": "H04R7/00", "inventive": false, "first": false, "tree": "[]"}, {"code": "H04R2499/11", "inventive": false, "first": false, "tree": "[]"}, {"code": "H03K17/9643", "inventive": true, "first": false, "tree": "[]"}, {"code": "H04R17/00", "inventive": true, "first": false, "tree": "[]"}, {"code": "H10N30/101", "inventive": true, "first": true, "tree": "[]"}, {"code": "H10N30/101", "inventive": true, "first": false, "tree": "[]"}]
Family ID: 70973274