Patent Description:
A two-dimensional distributed mode actuator may generate force in multiple dimensions to provide a system that includes the actuator, such as a smartphone, a wider output frequency range, a reduced actuator length, or both, compared to single-dimensional distributed mode actuators that generate force in a single direction, e.g., along a length of the single-dimensional actuator. For instance, the two-dimensional actuator may generate separate forces along a length and a width of the actuator and transfer these forces to a load, such as a speaker, to cause the load to generate sound. The two-dimensional distributed mode actuator also has different vertical, e.g., height, displacement along the width of the actuator, while a single-dimensional actuator generally has constant vertical displacement along with width.

Typically, a two-dimensional distributed mode actuator includes a plate connected to a stub. The plate has a width and a length that define a surface that generates force for the two-dimensional distributed mode actuator. The stub connects the plate to the panel, while at least one end of the plate along its width and its length are free to vibrate.

When the two-dimensional distributed mode actuator receives a drive signal, the two-dimensional distributed mode actuator can cause different sections of the plate's surface to move separately along a height axis. The height axis is perpendicular to the axes for the length and the width of the actuator.

The actuator also includes a damper that fits between a space between the plate's surface and the panel. As the plate vibrates it compresses the damper against the panel, absorbing vibration energy from the plate and changing the response of the actuator. It is believed that extending the damper along the width of the plate beyond the stub can improve the performance of the actuator-panel system by way of the forces created by the plate having an increased force amplitude at certain frequencies. For example, extending the damper's width can mitigate cancellation of output at frequencies between <NUM> and <NUM> in certain applications that has been observed for actuators having dampers that don't extend beyond the width of the stub.

Various aspects of the invention are summarized as follows.

The invention is defined in the appended independent claims. Preferred embodiments of the invention are defined in the dependent claims thereof.

In general, we describe a system according to claim <NUM> that includes a panel extending in a plane, an actuator attached to a surface of the panel, and an electronic control module in electrical communication with the actuator and programmed to activate the actuator during operation of the system to cause the vibration of the panel. The actuator is defined in claim <NUM> and comprises: a plate adapted to create a force to cause vibration of a load to generate sound waves during operation of the actuator, the plate having a width, WT, along a first direction at a first edge of the plate, the first edge being parallel to the first direction, and a length, LT, along a second direction orthogonal to the first direction, where WT is less than LT; a stub connected to the plate at the first edge, the stub having a width, WS, along the first direction at a region of connection to the plate that is less than WT, wherein a center point of the region of connection of the stub to the plate is offset from a center point of the first edge of the plate, the stub being configured to connect to the load to transfer the force from the plate to the load during operation of the actuator; and a damper supported by a surface of the plate facing the load and extending from the plate to contact the load when the stub is connected to the load, the damper having a width, WD, extending in the first direction by an amount greater than WS.

Embodiments of the system can include one or more of the following features. The region of connection of the stub to the first edge of the plate extends from a corner of the plate.

WD can be about <NUM>% of WT or more (e.g., about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more). In some embodiments, WD is substantially the same as WT.

Ws can be about <NUM>% of WT or less (e.g., about <NUM>% or less, about <NUM>% or less, about <NUM>% or less).

The damper can have a length along the second direction, LD, substantially less than LT.

The plate can include a piezoelectric material.

The actuator, at a second edge of the plate opposite the first edge, can be unattached to the panel. In some embodiments, the plate can include a third edge extending along the second direction and a fourth edge opposite the third edge, wherein the actuator is unattached to the panel along the third and fourth edges.

The surface of the plate can face the surface of the panel and extend parallel to the plane of the panel, and the stub can include a portion that extends away from the surface of the plate along a third direction orthogonal to the first and second directions, the portion of the stub providing a separation between the surface of the plate and the surface of the panel. The damper can have a thickness in the third direction substantially equal to the separation between the surface of the plate and the surface of the panel. The separation between the surface of the panel and the surface of the plate can be in a range from about <NUM> to about <NUM>.

The panel can include an electronic display panel.

We also describe a mobile device according to claim <NUM>.

Among other advantages, embodiments feature 2D DMA's that display improved output at certain frequency bands compared to similar actuator's that feature shortened dampers. The frequency response of the actuator, and precise range of improved output, can be varied depending on design parameters of the system, such as the physical dimensions of each component and each components material properties. Accordingly, device performance can be improved (e.g., optimized) by judicious selection of the damper's dimensions and material properties.

Other advantages will be evident from the description, drawings, and claims.

The disclosure features actuators for panel audio loudspeakers, such as distributed mode loudspeakers (DMLs). Such loudspeakers can be integrated into a mobile device, such as a mobile phone. For example, referring to <FIG>, a mobile device <NUM> includes a device chassis <NUM> and a touch panel display <NUM> including a flat panel display (e.g., an OLED or LCD display panel) that integrates a panel audio loudspeaker. Mobile device <NUM> interfaces with a user in a variety of ways, including by displaying images and receiving touch input via touch panel display <NUM>. Typically, a mobile device has a depth of approximately <NUM> or less, a width of <NUM> to <NUM> (e.g., <NUM> to <NUM>), and a height of <NUM> to <NUM> (e.g., <NUM> to <NUM>).

Mobile device <NUM> also produces audio output. The audio output is generated using a panel audio loudspeaker that creates sound by causing the flat panel display to vibrate. The display panel is coupled to an actuator, such as a two-dimensional distributed mode actuator, or 2D DMA. The actuator is a movable component arranged to provide a force to a panel, such as touch panel display <NUM>, causing the panel to vibrate. The vibrating panel generates human-audible sound waves, e.g., in the range of <NUM> to <NUM>.

In addition to producing sound output, mobile device <NUM> can also produces haptic output using the actuator. For example, the haptic output can correspond to vibrations in the range of <NUM> to <NUM>.

<FIG> also shows a dashed line that corresponds to the cross-sectional direction shown in <FIG>. Referring to <FIG>, a cross-section <NUM> of mobile device <NUM> illustrates device chassis <NUM> and touch panel display <NUM>. <FIG> also includes a Cartesian coordinate system with X, Y, and Z axes, for ease of reference. Device chassis <NUM> has a depth measured along the Z-direction and a width measured along the X-direction. Device chassis <NUM> also has a back panel, which is formed by the portion of device chassis <NUM> that extends primarily in the X-Y-plane. Mobile device <NUM> includes an electromagnet actuator <NUM>, which is housed behind display <NUM> in chassis <NUM> and affixed to the back side of display <NUM>. Generally, electromagnet actuator <NUM> is sized to fit within a volume constrained by other components housed in the chassis, including an electronic control module <NUM> and a battery <NUM>.

Referring to <FIG>, an embodiment of a 2D DMA <NUM> includes a plate <NUM> that extends along the y-direction from a free end <NUM> to an end <NUM> connected to a stub <NUM>. Stub <NUM> is attached to a surface of a display panel <NUM>. Effectively, plate <NUM> is a cantilever, anchored at a corner to stub <NUM>. DMA <NUM> also includes a damper <NUM> that is attached to a surface of plate <NUM> facing display panel <NUM>. A space <NUM> is provided between plate <NUM> and display panel <NUM>, extending from damper <NUM> to free end <NUM>.

<FIG> depict DMA <NUM> in more detail. Specifically, <FIG> shows a side view of DMA <NUM>, <FIG> shows an isometric view, and <FIG> shows a plan view. Plate <NUM> has a rectangular shape, extending a length, LT, along the y-direction and a width, WT, in the x-direction.

Plate <NUM> is a multilayer planar element, composed of layers <NUM>, <NUM>, and <NUM>, having a rectangular shape in the x-y plane, with a length LT and a width WT in the y- and x-directions, respectively. Generally, the length and width of plate <NUM> is selected, along with the mechanical properties of its compositional materials, so that the plate has vibrational resonances at frequencies appropriate for the application for which it is being used. Also, the dimensions can depend on the amount of space available for the plate in device <NUM>. In some embodiments, LT and WT are in a range from about <NUM> to about <NUM>. LT is larger than WT.

Layer <NUM>, <NUM>, and <NUM> generally include at least one layer of an appropriate type of piezoelectric material. For instance, one or more of these layers can be a ceramic or crystalline piezoelectric material. Examples of ceramic piezoelectric materials include barium titanate, lead zirconium titanate, bismuth ferrite, and sodium niobate, for example. Examples of crystalline piezoelectric materials include topaz, lead titanate, lithium niobate, and lithium tantalite. In some embodiments, layers <NUM> and <NUM> are piezoelectric materials while layer <NUM> is a rigid vane formed from, e.g., a rigid metal or rigid plastic. Layer <NUM> can extend into stub <NUM>, severing as a cantilever for plate <NUM>.

In some embodiments, plate <NUM> can be composed of additional layers. For instance, each piezoelectric layer can, itself, be composed of two more sublayers.

Generally, the thickness of plate <NUM> in the z-direction can vary depending on the desired mechanical properties the plate. In some embodiments, plate <NUM> has a thickness in a range from about <NUM> to about <NUM> (e.g., about <NUM> or more, about <NUM> or more, about <NUM> or more, about <NUM> or more, about <NUM> or less, about <NUM> or less, about <NUM> or less). The layer thickness of layers <NUM>, <NUM>, and <NUM> can vary as desired. For example, each layer have a thickness in a range of about <NUM> to about <NUM> (e.g., about <NUM> or more, about <NUM>. <NUM> or more, about <NUM> or less, about <NUM> or less).

Plate <NUM> is anchored to stub <NUM> along a portion of edge <NUM> of plate <NUM>. Stub <NUM> is mechanically secured to panel <NUM> at one end and to plate <NUM> at another end sufficient that the stub can efficiently transfer force from the plate to the panel. Stub <NUM> includes a portion <NUM> that extends in the z-direction beyond the surface of plate <NUM> toward panel <NUM>. This establishes the extent of space <NUM> between panel <NUM> of plate <NUM>. In some embodiments, space <NUM> is in a range from about <NUM> to about <NUM> (e.g., about <NUM> or more, about <NUM> or more, about <NUM> or less).

Stub <NUM> has a length, LS, in the y-direction and a width, Ws, in the x-direction. Ws is generally significantly smaller than WT, the plate's width, so that a significant portion of the plate along edge <NUM> is free to vibrate when activated. In some embodiments, Ws is less than <NUM>% of WT (e.g., about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less). Because none of the other edges of plate <NUM> are anchored to the panel, they too are free to vibrate when the plate is activated. Accordingly, plate <NUM> can support vibrational modes in both the x- and y-directions.

Panel <NUM> may be permanently, e.g., fixedly, connected to stub <NUM>, e.g., such that removal of panel <NUM> from stub <NUM> will likely damage panel <NUM>, stub <NUM>, or both. In some examples, panel <NUM> is removably connected to stub <NUM>, e.g., such that removal of panel <NUM> from stub <NUM> will not likely damage panel <NUM> or stub <NUM>. In some embodiments, an adhesive is used to connect a surface of stub <NUM> to panel <NUM>.

Stub <NUM> is typically formed from a hard material, e.g., that does not deform. For example, stub <NUM> may be formed from a metal, a hard plastic, or another appropriate type of material. In some embodiments, stub <NUM> is a composite structure, formed from two or more pieces of different materials.

Damper <NUM> is supported by the surface of plate <NUM> facing panel <NUM>. The damper has a thickness, TD, sufficient so that it contacts the surface of panel <NUM>, thereby providing a mechanical coupling between plate <NUM> and panel <NUM>. Damper <NUM> has a width, WD, extending in the x-direction greater than Ws and approximately equal to WT. Damper <NUM> has a length along the y-direction, LD, substantially less than LT. For example, LD can be about <NUM>% of LT or less (e.g., about <NUM>% or less, about <NUM>% or less, about <NUM>% or less, about <NUM>% or less).

Damper <NUM> is typically formed from one or more materials that have viscoelastic properties suitable for damping vibrations at certain frequencies. The damper materials should also be sufficiently environmentally robust so as not to degrade substantially during the lifetime of the DMA. Suitable materials can include organic or silicone polymers, e.g., rubbers. In some embodiments, neoprene is used. Commercially-available adhesive tapes, such as Tesatape (from Tesa Tape Inc. , Charlotte, NC), can be used in certain embodiments.

While actuator <NUM> includes a damper <NUM> that has the same width as plate <NUM> (i.e., WT = WD), other implementations are also possible. In general, while the width of damper <NUM> is greater than a width of stub <NUM>, the width of the damper can vary. For example, Ws can be about <NUM>% of WD or less (e.g., about <NUM>% of WD or less, about <NUM>% of WD or less, about <NUM>% of WD or less, about <NUM>% of WD or less, about <NUM>% of WD or less, about <NUM>% of WD or less, about <NUM>% of WD or less). WD can be about <NUM>% or more of WT (e.g., about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, about <NUM>% or more, such as about <NUM>% of WT). In general, the precise width of the damper can be included as a design variable in order to obtain a desired frequency response.

Furthermore, while the plate described above has a rectangular footprint in the x-y plane, more generally, other shapes are possible. For example, the dimension of the plate in either the x-direction and/or y-direction can vary along its length and width. Generally, the width of the plate is considered its maximum dimension in the x-direction, while the length of the plate is considered its maximum dimension in the y-direction. Similarly, either the stub and/or damper may have footprints that are not rectangular. In general, the shape of each of these element can be optimized, e.g., using computational simulation software, to a shape that provides a desired response spectrum.

In general, the force created by the plate includes a fundamental resonance peak at a fundamental frequency, F<NUM>, a first resonance peak at a first frequency, F<NUM>, and a second resonance peak at a second frequency, F<NUM>. These resonances represent frequencies at which the force amplitude, which is a measure of the output of the actuator, is a local maximum. Generally, for a fixed input power, the efficiency of the actuator will decrease between these resonances. For actuators designed to produce audio signals in a panel audio loudspeaker, such as actuator <NUM>, F<NUM> is typically in a range from about <NUM> to about <NUM> (e.g., from about <NUM> to about <NUM>), F<NUM> is typically in a range from about <NUM> to about <NUM> (e.g., from about <NUM> to about <NUM>), and F<NUM> is typically in a range from about <NUM> to about <NUM>. These resonance frequencies depend on, among other parameters, on the width, WD, of damper <NUM>. It is believed that, by using a damper that extends beyond the width of the stub, an output of the plate is increased for at least some frequencies between F<NUM> and F<NUM> compared to the same plate but for which WD is the same as Ws. This advantageously improves the efficiency of the actuator. For at least one frequency between F<NUM> and F<NUM>, the force created by the plate is at least <NUM> times (e.g., about <NUM> times or more, about <NUM> times or more, about <NUM> times or more) greater compared to the same plate but for which WD is the same as WS.

<FIG> is a plot of load velocity (in ms-<NUM>) as a function of frequency comparing the effect of a damper that is <NUM>/<NUM> the width of the plate (solid line) to one that is the full width of the plate (dashed line). The fundamental frequency, F<NUM>, is at approximately the same frequency for both damper widths, however, the DMA with the shorter damper demonstrates a resonance peak, F<NUM>, at a lower frequency compared to the full-width damper. In particular, the <NUM>/<NUM> width damper has peak F<NUM> at approximately <NUM>, while the full width damper has a corresponding peak at approximately <NUM>. Notably, also, the <NUM>/<NUM> width damper exhibits a steep drop in load velocity between F<NUM> and a further peak at approximately <NUM>, as well as a step <NUM> at approximately <NUM>. In contrast, the full width damper does not demonstrate a similar drop in load velocity in the <NUM> to <NUM> range. This suggests that the efficiency of the DMA with the full width damper will be higher than the efficiency of the <NUM>/<NUM> damper, at least over the frequency range from <NUM> to <NUM>.

<FIG> illustrate the effect of damper width on load velocity (in ms-<NUM>) at two different frequencies of interest, namely <NUM> and <NUM>. These results were generated by simulation. As is evident from this plot, low frequency performance (e.g., at <NUM>) is relatively unchanged as the damper width is increased from <NUM> to <NUM>. At higher frequencies (<NUM> in this example), however, damper width has a significant impact on load velocity, increasing the velocity over an order of magnitude from a low value at <NUM> damper width, to a maximum value at <NUM>.

<FIG> compares the performance of two DMA's having dampers with differing widths. Specifically, <FIG> shows a plot of results of a blocked force measurement taken for a DMA with a damper that has a width that is <NUM>/<NUM> the width of the plate (line <NUM>) and measurements taken for a similar DMA in which the damper has a width that is substantially equal to the width of the plate (line <NUM>). There are several notable differences between the two spectra. First, the DMA with the extended damper demonstrates a fundamental frequency F<NUM> at a slightly higher frequency than the DMA with the shorter damper. This frequency shift is identified as ΔF<NUM> in <FIG>, and is about <NUM>. Second, the DMA with the shorter damper (line <NUM>) exhibits a notable step in its spectra at approximately <NUM>. This is identified as <NUM> in <FIG>. The extended damper does not display such as step, but a much smoother increase in response from approximately <NUM> to F<NUM>. Third, at the frequency range <NUM>, from approximately <NUM> to <NUM>, the DMA with the shorter damper exhibits a significant drop in force output over this range. In contrast, the drop in force output from the DMA with the extended damper is significantly smaller. Accordingly, it is believed that that the efficiency of the DMA with the full width damper will be higher than the efficiency of the <NUM>/<NUM> damper, at least over the frequency range <NUM>.

In general, the disclosed actuators are controlled by an electronic control module, e.g., electronic control module <NUM> in <FIG> above. In general, electronic control modules are composed of one or more electronic components that receive input from one or more sensors and/or signal receivers of the mobile phone, process the input, and generate and deliver signal waveforms that cause actuator <NUM> to provide a suitable haptic response. Referring to <FIG>, an exemplary electronic control module <NUM> of a mobile device, such as mobile phone <NUM>, includes a processor <NUM>, memory <NUM>, a display driver <NUM>, a signal generator <NUM>, an input/output (I/O) module <NUM>, and a network/communications module <NUM>. These components are in electrical communication with one another (e.g., via a signal bus) and with actuator <NUM>.

Processor <NUM> may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, processor <NUM> can be a microprocessor, a central processing unit (CPU), an application-specific integrated circuit (ASIC), a digital signal processor (DSP), or combinations of such devices.

Memory <NUM> has various instructions, computer programs or other data stored thereon. The instructions or computer programs may be configured to perform one or more of the operations or functions described with respect to the mobile device. For example, the instructions may be configured to control or coordinate the operation of the device's display via display driver <NUM>, waveform generator <NUM>, one or more components of I/O module <NUM>, one or more communication channels accessible via network/communications module <NUM>, one or more sensors (e.g., biometric sensors, temperature sensors, accelerometers, optical sensors, barometric sensors, moisture sensors and so on), and/or actuator <NUM>.

Signal generator <NUM> is configured to produce AC waveforms of varying amplitudes, frequency, and/or pulse profiles suitable for actuator <NUM> and producing acoustic and/or haptic responses via the actuator. Although depicted as a separate component, in some embodiments, signal generator <NUM> can be part of processor <NUM>. In some embodiments, signal generator <NUM> can include an amplifier, e.g., as an integral or separate component thereof.

Memory <NUM> can store electronic data that can be used by the mobile device. For example, memory <NUM> can store electrical data or content such as, for example, audio and video files, documents and applications, device settings and user preferences, timing and control signals or data for the various modules, data structures or databases, and so on. Memory <NUM> may also store instructions for recreating the various types of waveforms that may be used by signal generator <NUM> to generate signals for actuator <NUM>. Memory <NUM> may be any type of memory such as, for example, random access memory, read-only memory, Flash memory, removable memory, or other types of storage elements, or combinations of such devices.

As briefly discussed above, electronic control module <NUM> may include various input and output components represented in <FIG> as I/O module <NUM>. Although the components of I/O module <NUM> are represented as a single item in <FIG>, the mobile device may include a number of different input components, including buttons, microphones, switches, and dials for accepting user input. In some embodiments, the components of I/O module <NUM> may include one or more touch sensor and/or force sensors. For example, the mobile device's display may include one or more touch sensors and/or one or more force sensors that enable a user to provide input to the mobile device.

Each of the components of I/O module <NUM> may include specialized circuitry for generating signals or data. In some cases, the components may produce or provide feedback for application-specific input that corresponds to a prompt or user interface object presented on the display.

As noted above, network/communications module <NUM> includes one or more communication channels. These communication channels can include one or more wireless interfaces that provide communications between processor <NUM> and an external device or other electronic device. In general, the communication channels may be configured to transmit and receive data and/or signals that may be interpreted by instructions executed on processor <NUM>. In some cases, the external device is part of an external communication network that is configured to exchange data with other devices. Generally, the wireless interface may include, without limitation, radio frequency, optical, acoustic, and/or magnetic signals and may be configured to operate over a wireless interface or protocol. Example wireless interfaces include radio frequency cellular interfaces, fiber optic interfaces, acoustic interfaces, Bluetooth interfaces, Near Field Communication interfaces, infrared interfaces, USB interfaces, Wi-Fi interfaces, TCP/IP interfaces, network communications interfaces, or any conventional communication interfaces.

In some implementations, one or more of the communication channels of network/communications module <NUM> may include a wireless communication channel between the mobile device and another device, such as another mobile phone, tablet, computer, or the like. In some cases, output, audio output, haptic output or visual display elements may be transmitted directly to the other device for output. For example, an audible alert or visual warning may be transmitted from the electronic device <NUM> to a mobile phone for output on that device and vice versa. Similarly, the network/communications module <NUM> may be configured to receive input provided on another device to control the mobile device. For example, an audible alert, visual notification, or haptic alert (or instructions therefor) may be transmitted from the external device to the mobile device for presentation.

Claim 1:
An actuator (<NUM>), comprising:
a plate (<NUM>) adapted to create a force to cause vibration of a load (<NUM>) to generate sound waves during operation of the actuator, the plate having a width, WT, along a first direction at a first edge of the plate, the first edge being parallel to the first direction, and a length, LT, along a second direction orthogonal to the first direction, where WT is less than LT;
a stub (<NUM>) connected to the plate at the first edge, the stub having a width, Ws, along the first direction at a region of connection to the plate that is less than WT, wherein a center point of the region of connection of the stub to the plate is offset from a center point of the first edge of the plate, the stub being configured to connect to the load to transfer the force from the plate to the load during operation of the actuator; and
a damper (<NUM>) supported by a surface of the plate facing the load and extending from the plate to contact the load when the stub is connected to the load, the damper having a width, WD, extending in the first direction by an amount greater than Ws.