Patent Grant
12143771
This specification relates generally to audio speakers.
Many conventional moving magnet actuators can be damaged as a result of the actuators being dropped. In particular, the voice coil and magnets of the moving magnet actuators can be fragile, making them especially prone to drop damage.
Disclosed are actuator modules with improved damage resistance compared to conventional modules. The actuator modules may be suitable for panel audio loudspeakers, especially those incorporated in mobile devices (e.g., mobile phones). For example, implementations of such actuator modules feature components, such as a back plate, suspension, and a frame, which are configured to effectively dissipate a force that results from the actuator module being dropped, therefore preventing damage to the components of the actuator module.
In a general aspect, an actuator module includes a baseplate extending in a plane, a voice coil connected to the baseplate, and a magnet assembly. The actuator module also includes a rigid frame attached to the baseplate, the rigid frame comprising four stubs. The actuator module further includes a pair of springs suspending the magnet assembly relative to the frame and baseplate so that the voice coil extends into the air gap, the pair of springs including a first and second spring each shaped as a loop defining an aperture sized to accommodate motion of the magnet assembly along a direction of the coil axis, the first spring being attached to the frame at a first pair of the four stubs, the second spring being attached to the frame at a second pair of the four stubs, and both being attached to separate portions of the magnet assembly.
In a first aspect, an actuator module includes an actuator module that includes a baseplate extending in a plane and a voice coil connected to the baseplate, the voice coil defining a coil axis perpendicular to the plane. The actuator module also includes a magnet assembly that includes a first side facing the baseplate, a second side facing away from the baseplate, a first pair of sidewalls on opposing sides of the magnet assembly, and a second pair of sidewalls on opposing sides of the magnetic assembly and adjacent to the first pair of sidewalls. The actuator module further includes a rigid frame attached to the baseplate, the rigid frame including four stubs each facing a corresponding one of the sidewalls. The actuator module also includes a pair of springs suspending the magnet assembly relative to the frame and the baseplate so that the voice coil extends into the air gap. The pair of springs including a first spring shaped as a loop defining an aperture sized to accommodate motion of the magnet assembly along a direction of the coil axis, the first spring being attached to the frame at a first pair of the four stubs respectively facing the first pair of sidewalls and attached to the magnet assembly at the second pair of sidewalls of the magnet assembly on the second side of the magnet assembly. The pair of springs including a second spring shaped as a loop defining an aperture sized to accommodate motion of the magnet assembly along the direction of the coil axis, the second spring being attached to the frame at a second pair of the four stubs respectively facing the second pair of sidewalls and attached to the magnet assembly at the first pair of sidewalls of the magnet assembly on the first side of the magnet assembly.
The first side may be referred to as a back side of the magnet assembly.
The second side may be referred to as a front side of the magnet assembly.
The magnet assembly may define the air gap.
The air gap may be a recess defined in the second side of the magnet assembly. The recess may be an annular recess.
By the springs being attached to the magnet assembly on the first side or the second side of the magnet assembly, it is not necessary for the connection point to be at the furthest extent of the magnet assembly at the first side or the second side. Rather, the connection point may be generally at, or around, the respective side. For example, a recess may be provide in the first side or the second side to accommodate part of the spring, meaning that the point of connection is offset slightly (i.e. recessed from) from the outermost part of the magnet assembly at the first side or the second side.
The first spring and/or the second spring may each comprise a single component, or may be formed from a plurality of spring components (e.g. two spring components). As such, the “loop” does not need to be continuous, but may be defined by a combination of spring components.
Implementations of the apparatus can include one or more of the following features.
In some implementations, a width of each spring varies along a circumference of the spring. The width of each spring may be said to vary along a circumference of the spring. This is not intended to require that the spring in circular, by rather that the width is different at different points of the loop. By width, it may be meant a dimension in a direction parallel to a plane perpendicular to the coil axis.
In some implementations, a width of each spring varies along a perimeter of the spring.
The width of each spring can be a local maximum at a location of the spring where the spring attaches to the frame. The width of each spring can be a local maximum at a location of the spring where the spring attaches to the magnet assembly.
In some implementations, the spring includes a pair of first segments on opposing sides of the corresponding aperture, the pair of first segments extending parallel to each other, and each spring further including a pair of second segments on opposing sides of the corresponding aperture, the pair of second segments extending perpendicular to the pair of first segments. The pair of first segments can each extend along a corresponding straight line and have a maximum width at a midpoint of the segment. Each spring can be attached to the frame at the midpoint of the pair of first segments.
An area of attachment of each spring to the frame can extend 0.8 mm or more (e.g., 1 mm or more, 1.2 mm or more, 1.3 mm or more, 1.4 mm or more, 1.5 mm or more, 1.6 mm or more, 1.7 mm or more, 1.8 mm or more, 1.9 mm or more, 2 mm or more, 2.1 mm or more, 2.2 mm or more, 2.5 mm or more, 3 mm or less) along the straight line of the corresponding first segment. An area of attachment of each spring to the frame can extend 0.45 mm or more (e.g., 0.5 mm or more, 0.55 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, 1 mm or less 0.2 mm or more (0.3 mm or more, 0.4 mm or more, 0.5 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, 1 mm or less) along a direction perpendicular to the straight line of the corresponding first segment.
The pair of second segments can each including a pair of arms extending along a straight line and an indented portion between the arms, the indented portion being offset from the straight line towards the aperture of the corresponding spring. Each spring can be attached to the magnet assembly at the indented portions of the second segments. In some implementations, the indented portions are each at a midpoint of the corresponding second segments. A width of each second segment can be a maximum at the corresponding indented portion.
In some implementations, the first segments each extend the same length. In some implementations, the second segments each extend the same length. In other implementations, the first and second segments each extend the same length. Each first segment can attach to an adjacent second segment at a corner of the corresponding spring. A width of the spring can be a minimum at the corners of the spring.
In some implementations, each spring has a depth along a direction of the coil axis in a range from 0.1 mm to 0.3 mm (e.g., 0.15 mm or more, 0.16 mm or more, 0.17 mm or more, 0.18 mm or more, e.g., 0.25 mm or less, 0.2 mm or less). Each spring can have a minimum width to depth ratio in a range from 1.1 to 3.75 (e.g., 3.5 or less, 3 or less, 2.5 or less, 2 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, e.g., 1.2 or more, 1.3 or more, 1.4 or more).
Each spring can be formed from a single piece of material. Each spring is formed from a metal or alloy. In some implementations, each spring is formed from stainless steel.
The magnet assembly can further include a back plate and sidewalls defining a cup, an inner element including a center magnet mounted within the cup, the back plate extending parallel to the plane, wherein the sidewalls and inner element are separated by the air gap.
Each spring can have a radial dimension that is the sum of (i) the local maximum width of the spring at the location of the spring where the spring attaches to the frame and (ii) a clearance distance between a first point along an edge of the spring facing the aperture at the location of the spring where the spring attaches to the frame and a second point along an edge of the magnet assembly, the clearance distance being measured in a radial direction perpendicular to the coil axis. Each spring can also have an excursion distance that is a maximum distance the spring is displaced in the direction of the coil axis. Each spring can have a radial dimension to excursion distance ratio of 1.5:1 or less (e.g., 1.4:1 or less, 1.3:1 or less; 1.2:1 or less, 1.1:1 or less, 1:1 or more). Where the magnet assembly comprises a back plate, the clearance may be a distance between a first point along an edge of the spring facing the aperture at the location of the spring where the spring attaches to the frame and a second point along an edge of the back plate.
In another aspect, the subject matter features a panel audio loudspeaker including the actuator module and a panel attached to the baseplate of the actuator module. The panel can include a display panel.
In yet another aspect, a mobile device or wearable device includes a housing, the panel audio loudspeaker, and an electronic control module electrically coupled to the voice coil of the actuator module and programmed to energize the voice coil to couple vibrations to the panel to produce an audio response from the panel. The mobile device can be a mobile phone or a tablet computer. The wearable device can be a smart watch or head-mounted display.
Among other advantages, embodiments feature an actuator module that has a decreased chance of failure from mechanical stress caused by the actuator module being dropped, as compared to conventional actuator modules.
Other advantages will be evident from the description, drawings, and claims.
Like reference symbols in the various drawings indicate like elements.
Referring to
Actuator module 100 can be relatively compact. For example, hood 102, which has a substantially square profile in the x-y plane, can have an edge length (i.e., in the x- or y-directions) of about 25 mm or less (e.g., 20 mm or less, 15 mm or less, such as 14 mm, 12 mm, 10 mm or less). The actuator module's height (i.e., its dimension in the z-direction) can be about 10 mm or less (e.g., 8 mm or less, 6 mm or less, 5 mm or less).
During operation, an electric current is applied to voice coil 106 via PCB 108. The resulting magnetic flux interacts with a suspended magnet that is part of motor module 104 (discussed below), which generates a force, i.e., the Lorentz force, that varies proportionally with a change in the current. The force gives rise to vibrations that are transferred via baseplate 110 to the panel.
Referring to
The magnet assembly also includes a front center plate 212 and a front ring plate 214, which are attached to bottom surfaces of center magnet 208 and ring magnet 210, respectively. The magnet assembly further includes a bucking magnet 218, which is attached to front center plate 212. Front center plate 212 and front ring plate 214 are sized and shaped so that the front center plate fits within a gap defined by the front ring plate, as shown by their relative placement in
At each corner of frame 204 are posts 204a-204d that attach the frame to hood 102 and baseplate 110. That is, top surfaces of posts 204a-204d are attached to hood 102, while bottom surfaces of the posts are attached to baseplate 110. Frame 204 also includes stubs 204e-204h, which are positioned on the sides of the frame, between two of posts 204a-204d. Stubs 204e and 204g each have a bottom surface that attaches to baseplate 110. Stubs 204f and 204h each have a top surface that attaches to hood 102. Stubs 204e and 204g are provided on opposite sides of the frame 204 from one another, while stubs 204f and 204h are also provided on opposite sides of the frame 204 from one another.
While frame 204 has an approximately square shape when viewed in the xy-plane, each corner of the frame is curved so that the frame has dull corners. Between each of the corners of frame 204 are portions of the frame that are substantially straight along their outside edges. The straight portions of frame 204 attach the frame to hood 102. Stubs 204e-204h extend in the z-direction allowing for an increased area of contact with hood 102, as compared to a frame that does not include the stubs.
While the straight portions of frame 204 attach to hood 102, the outside edge of springs 202a and 202b do not contact hood 102. That is, a first distance measured between the inside edge of hood 102 and the outside edge of spring 202a or 202b is greater than a second distance measured between the inside edge of hood 102 and the outside edge of the straight portions of frame 204, where the first and second distances are measured parallel to the x or y-axes.
Spring 202a is attached (e.g., welded) to frame 204 at connection points 216a and 216b. Spring 202b is attached to frame 204 at a connection point 218c. While obscured in the view of
Springs 202a and 202b share approximately the same shape when viewed in the xy-plane. The corners of springs 202a and 202b, as viewed in the xy-plane, are curved. Two sides of springs 202a and 202b, between the corners of the springs, are substantially straight. The remaining two sides of springs 202a and 202b are curved inward in a “c” shape. One example of the benefit provided by the c-shaped portions of springs 202a and 202b is that they allow stubs 204e-204h to extend in the z-direction.
Spring 202a is attached to back plate 206 at connection points 206a and 206b. Back plate 206 includes two slots at the locations of connection points 206a and 206b, so that spring 202a is significantly flush with the top surface of the back plate. That is, the depth of the slots in the z-direction maybe approximately equal to the thickness of the spring 202a at the connection points 206a, 206b. The shape of the slots of back plate 206 are curved in approximately the same c-shaped curvature as are springs 202a and 202b. The c-shaped portions of spring 202a and the corresponding c-shaped slot of back plate 206 facilitate the connection between these components at connection points 206a and 206b.
A width of each spring 202a and 202b varies along a length of the spring. For example, a first width of spring 202a at connection point 216a or 216b is greater than a second width of the spring at the corners of the spring. The first width can be about 0.8 mm or less (e.g., 0.75 mm or less, 0.7 mm or less, 0.65 mm or less), while the second width can be about 0.35 mm or less (e.g., 0.3 mm or less, 0.25 mm or less, 0.2 mm or less). Similarly, a third width of spring 202a at connection points 206a or 206b is greater than the second width of the spring. The third width can be about 0.55 mm or less (e.g., 0.5 mm or less, 0.45 mm or less, 0.4 mm or less). The width of the spring decreases as it extends along any midpoint that is on the spring and between two corners of the spring to any corner of the spring. That is, as spring 202a extends from connection point 206a or 206b to a closest corner of the spring, the width of the spring decreases. Similarly, as spring 202a extends from connection point 216a or 216b to a closest corner of the spring, the width of the spring decreases.
While spring 202a is attached to back plate 206, spring 202b is attached to a bottom surface of front ring plate 214.
During the operation of actuator module 100, springs 202a and 202b bend in the z-direction. By virtue of their connection to springs 202a and 202b, back plate 206, center magnet 208, ring magnet 210, front center plate 212, front ring plate 214, and bucking magnet 218 also move in the z-direction. The locations of the connections of springs 202a and 202b to motor module 104 are chosen so that the motor module has a desired resonant frequency.
Spring 202b includes c-shaped notches that correspond with connection point 214a and connection point 214b (not shown). The location of connection points 206a and 206b of back plate 206 and connection points 214a and 214b of front ring plate 214 can be chosen to facilitate motor module 104 to exhibit a desired resonant behavior. For example, connection points 206a and 206b are not placed above connection points 214a and 214b. This placement of the connection points facilitates motor module 104 to exhibit a desired resonant behavior, e.g., to facilitate the motor module to exhibit a desired rocking mode at a particular rocking frequency.
The top surface of back plate 206 (i.e., the surface having rectangular dimensions with rounded corners visible with respect to
For example, if actuator module 100 is dropped, springs 202a and 202b and their corresponding connection points can facilitate motor module 104, e.g., the magnet assembly of the motor module, to exhibit a rocking mode. The frequency of the rocking mode can be at roughly twice a resonant frequency displayed by motor module 104. Because the rocking mode is at roughly twice the resonant frequency of motor module 104, it is not a favorable excitation for the motor module during normal operation. However, because the rocking mode is the first normal mode above the resonant frequency, motor module 104 can exhibit the rocking mode if actuator module 100 is dropped, and the force of the impact can be at least partially dissipated by the rocking mode.
The size and shape of the springs, e.g., the width to depth ratio of the springs, is chosen to favor displacement of motor module 104 in the z-direction over displacement of the motor module in the x or y-directions. However, during abnormal operation of actuator module 100, such as when the actuator is dropped, there may be some lateral displacement (e.g., displacement in the x or y-directions) of motor module 104. The lateral displacement causes uneven forces in the z-direction, causing the rocking mode which dissipates the energy of the drop over time.
Not only can the placement of the connection points 216a, 216b, 214a, and 214b be chosen to facilitate a desired resonant behavior of motor module 104, the shape of springs 202a and 202b can affect the resonant behavior of the motor module. For example, the depth of springs 202a and 202b, as measured in the z-direction, or the width of the springs, as measured in the x and y-directions, can be increased or decreased to promote a desired resonant behavior of motor module 104, e.g., to promote a certain fundamental frequency. In addition, the depth of frame 204 or the width of the frame can be increased or decreased to promote a desired resonant behavior of motor module 104.
The overall dimensions of springs 202a and 202b, as measured in the x and y-dimensions, can be approximately equal. For example, springs 202a and 202b can fit within a square having side lengths of about 13.5 mm or less (e.g., 13.25 mm or less, 13 mm or less, 12.75 mm or less, 12.5 mm or less). Springs 202a and 202b can be made from a hard metal or alloy having a high yield strength, e.g., a yield strength of 1400 MPa or greater. For example, springs 202a and 202b can be made from stainless steel, e.g., one having a high-cycle fatigue strength, such as 50% cold-worked 301 stainless steel. Springs 202a and 202b are formed from a single piece of material, although in some implementations, the springs can be formed from multiple pieces of material or multiple pieces of different materials that are adhered together (e.g., using an adhesive or weld).
When motor module 104, including one or more springs of the module, is part of a mobile device, e.g., a mobile phone, it is advantageous to minimize the size of the motor module so that it can fit within a device chassis that may house other components of the mobile device. For example, when an actuator module that includes the motor module is used to drive a panel audio loudspeaker of a mobile device, during operation of the actuator, the spring is displaced in the z-direction, e.g., to provide a force to the panel audio loudspeaker. Achieving a desirable amount of spring displacement, or excursion, using conventional suspension components, e.g., a conventional spider component, may result in a speaker that does not fit within the size constraints of a mobile device. A conventional spider component may have a radial dimension, to excursion ratio of 10:1, where the radial dimension is measured from a central axis to an outer edge of the component. The shape of the springs of motor module 104 are chosen so as to achieve the desired displaced in the z-direction while minimizing the radial dimension of the spring, where the radial dimension is the sum of the maximum width of the spring plus the clearance of the spring. For example, springs 202a and 202b have a radial dimension of approximately 0.75 mm and an excursion of approximately 0.5 mm, leading to a 1.5:1 radial dimension to excursion ratio. In some implementations, the radial dimension to excursion ratio can be less than 1.5:1 (e.g., 1.4:1 or less, 1.3:1 or less, 1.2:1 or less, 1.1:1 or less).
During operation of the actuator module, moving components of the motor module 104 (e.g., back plate 206, center magnet 208, ring magnet 210, front center plate 212, front ring plate 214, and bucking magnet 218) are displaced in the z-direction. The springs to which the moving components are attached have a frequency response that includes a fundamental frequency, a rocking frequency, and a shearing frequency that are functions of the mass of the moving components, the spring constant of the springs, the width of the springs, as measured in the x or y-directions, and the depth of the springs, as measured in the z-direction. The fundamental frequency of the spring can be on the order of 280 Hz or less (e.g., 270 Hz or less, 260 Hz or less, 250 Hz or less, 240 Hz or less, 230 Hz or less).
When the springs exhibit a shearing frequency, the moving components of the module are displaced in the x and/or y-directions. The displacement in the x and/or y-directions can be on the order of 0.2 mm or less (e.g., 0.15 mm or less, 0.1 mm or less, 0.05 mm or less, 0.025 mm or less). The shearing frequency can be many times the fundamental frequency. For example, the shearing frequency of the motor module can be on the order of 1150 Hz or less (e.g., 1100 Hz or less, 1050 Hz or less, 1000 Hz or less, 950 Hz or less, 900 Hz or less).
While
Spring 300A has a pair of segments 302a and 302b that extend the same distance in the x-direction and are bordered at their ends by solid black lines. Segments 302a and 302b include connection points 304a and 304b, respectively, which are positioned at the midpoint of each segment. Connection points 304a and 304b are finite areas of spring 300A at which the spring is attached to areas of frame 204. Spring 300A also includes a pair of segments 306a and 306b that extend the same distance in the y-direction and are bordered at their ends by solid black lines. Segments 306a and 306b include connection points 308a and 308b, respectively, which are positioned at the midpoint of each segment, at an indented portion of the segment.
Connection points 308a and 308b are finite areas of spring 300A at which the spring is attached to either areas of back plate 206 or areas of front ring plate 214, depending on the position of the spring relative to the magnets of motor module 104. For example, if spring 300A is positioned above center magnet 208, i.e., like spring 202a, then spring 300A is attached to back plate 206 at connection points 206a and 206b. If instead spring 300A is positioned below center magnet 208, i.e., like spring 202b, then spring 300A is attached to front ring plate 214 at connection points 214a and 214b.
In some implementations, spring 300A is welded to components of motor module 104 at the connection points 304a, 304b, 308a, and 308b. When spring 300A is welded, the connection points and their surrounding areas may be more fragile than other portions of the spring that are farther from the weld site. Accordingly, it is advantageous to distribute the stress on spring 300A so that there is relatively low stress at and near the connection points.
Segments 302a, 302b, 306a and 306b are each connected to rounded corners. The shape and width of the corners helps to evenly distribute the stress experienced during operation of the actuator module along the corner and along each segment of spring 300A. Spring 300A has a minimum width, Wc, at the corners of the spring. The minimum width refers to the minimum dimension measured in the xy-plane, e.g., along the radius of curvature of each corner. Wc is approximately 0.31 mm.
The shape and width, as measured in the y-direction, of segments 302a and 302b are chosen to distribute stress along the length of the segment. The width of segments 302a and 302b increases from a width at the boundaries of each segment and the adjacent corners, to a local maximum, Wmax1, at connection points 304a and 304b, respectively. The width Wmax1 is approximately 0.55 mm. The shape and dimensions of spring 300A promote a certain frequency response of the spring. Spring 300A has a fundamental frequency of 255 Hz, a rocking frequency of 520 Hz, and a shearing frequency of 990 Hz.
While the width, as measured in the y-direction, of segments 302a and 302b increases along a portion of the segments, the width, as measured in the x-direction, of segments 306a and 306b, also increases along a portion of the segments to distribute stress along the length of the segments. The width of segments 306a and 306b increases from a width at the boundaries of each segment and the adjacent corners, to a local maximum, Wmax2, at connection points 308a and 308b, respectively. The width Wmax2 is approximately 0.83 mm.
The area of attachment between spring 300A and frame 204 also affects the frequency response of the spring. Increasing the area of attachment decreases the length of spring 300A that is free to vibrate, which in turn changes the distribution of force along the spring. The area of attachment is dictated by the width of the spring and the length of connection points 304a and 304b, which is labeled L1 in
Not only does the width of spring 300A affect the distribution of stress along the spring, so too does the depth of the spring, as measured in the z-direction. The depth of spring 300A is approximately 0.1778 mm. The behavior and stress resistance of spring 300A changes according to the width to depth ratio of spring 300A. The width to depth ratio of a spring is the ratio of the width at connection point 304a or 304b, i.e., Wmax1, to the depth of the spring. A positive width to depth ratio (i.e. a width to depth ratio greater than 1) favors motion of the moving components of motor module 104 in the z-direction, as opposed to the x and/or y-directions. Spring 300A has a width to depth ratio of 1.65.
The physical dimensions of spring 300A can be increased or decreased to promote a certain change in the frequency response of the spring. For example, increasing the width or the depth of the spring results in increases in the fundamental frequency, rocking frequency, and shearing frequency of the spring. In particular, increasing the corner width results in increases in the fundamental frequency, rocking frequency, and shearing frequency. Increasing the corner width also results in an increase in the stress experienced by the spring at and around the area of attachment of the spring. Increasing the area of attachment between the spring and the frame increases the fundamental frequency, rocking frequency, and shearing frequency of the spring.
While
Spring 300F includes connection points 312a, 312b, 312c, and 312d. Connection points 312a-312d are finite areas of spring 300F at which the spring is attached to areas of frame 204. Connection points 312a and 312b are positioned at the ends of piece 310, while connection points 312c and 312d are positioned at the ends of piece 320. Spring 300F also includes connection points 314a and 314b, which are finite areas of the spring at which it is attached to either areas of back plate 206 or to areas of front ring plate 214, depending on the position of the spring relative to the magnets of motor module 104. The length of the portion of spring 300F that is connected to frame 204 at connection points 312a-312d is labeled L3. L3 is approximately 0.5 mm.
Spring 300F′ includes connection points 312a′, 312b′, 312c′, and 312d′. Connection points 312a′-312d′ are finite areas of spring 300F′ at which the spring is attached to areas of frame 204. Connection points 312a′ and 312b′ are positioned at the ends of piece 310′, while connection points 312c′ and 312d′ are positioned at the ends of piece 320′. Spring 300F′ also includes connection points 314a′ and 314b′, which are finite areas of the spring at which it is attached to either areas of back plate 206 or to areas of front ring plate 214, depending on the position of the spring relative to the magnets of motor module 104. The length of the portion of spring 300F′ that is connected to frame 204 at connection points 312a′-312d′ is labeled L′3.
Spring 300F has a first local maximum width, Wmax4, at connection points 312a-312d and a second local maximum width, Wmax5, at connection points 314a and 314b. Wmax4 and Wmax5 are approximately 0.6 mm and 0.7 mm, respectively. The width of spring 300F tapers along a portion of the spring from the first local maximum width to a corner of the spring. The width at the corner of spring 300F, Wc2, is a local minimum width of the spring 300F. Wc2 is approximately 0.22 mm. The width of spring 300F also tapers along a portion of the spring from the second local maximum width to the corner of the spring.
Spring 300F′ has a first local maximum width, W′max4, at connection points 312a′-312d′ and a second local maximum width, W′max5, at connection points 314a′ and 314b′. The width of spring 300F′ tapers along a portion of the spring from the first local maximum width to a corner of the spring. The width at the corner of spring 300F′, W′c2, is a local minimum width of the spring 300F′. The width of spring 300F′ also tapers along a portion of the spring from the second local maximum width to the corner of the spring.
Referring now to springs 300A-300F and 300F′, the springs can be sized and shaped according to the following specifications. For example, the maximum width along the portion of the spring that connects to frame 204 can be 0.2 mm or more (0.3 mm or more, 0.4 mm or more, 0.5 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, 1 mm or less). The maximum width along the portion of the spring that connects to either back plate 206 or front plate 214 can be 0.3 mm or more (0.4 mm or more, 0.5 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, 1 mm or less). The width at the corner of the springs can be 0.35 mm or less (e.g., 0.3 mm or less, 0.275 mm or less, 0.25 mm or less, 0.225 or less, 0.2 mm or less).
The spring depth ranges from approximately 0.1 mm to approximately 0.3 mm (e.g., 0.15 mm or more, 0.16 mm or more, 0.17 mm or more, 0.18 mm or more, e.g., 0.25 mm or less, 0.2 mm or less). The springs have a minimum width to depth ratio in a range from 1.1 to 3.75 (e.g., 3.5 or less, 3 or less, 2.5 or less, 2 or less, 1.9 or less, 1.8 or less, 1.7 or less, 1.6 or less, 1.5 or less, e.g., 1.2 or more, 1.3 or more, 1.4 or more). The lateral stiffness of the spring, e.g., as measured in the x and/or y-directions, should be greater than the stiffness of the spring in the z-direction by 2 times or more, (e.g., 4.5 times or more, 5 times or more, 5.5 times or more, 6 times or more).
The length of the connection points that connect springs 300A-300E to frame 204 can be 0.8 mm or more (e.g., 1 mm or more, 1.2 mm or more, 1.3 mm or more, 1.4 mm or more, 1.5 mm or more, 1.6 mm or more, 1.7 mm or more, 1.8 mm or more, 1.9 mm or more, 2 mm or more, 2.1 mm or more, 2.2 mm or more, 2.5 mm or more, 3 mm or less). The length of connection points 312a-312d and the length of connection points 312a′-312d′ can be 0.4 mm or more (e.g., 0.5 mm or more, 0.6 mm or more, 0.65 mm or more, 0.7 mm or more, 0.75 mm or more, 0.8 mm or more, 0.85 mm or more, 0.9 mm or more, 0.95 mm or more, 1 mm or more, 1.05 mm or more, 1.1 mm or more, 1.25 mm or more, 1.5 mm or less).
Referring now to
During the operation of actuator module 100, voice coil 106 is energized. When energized, voice coil 106 induces a magnetic field in air gap 402. Center magnet 208 and ring magnet 210 each experience a force due to the interaction of their magnetic fields with that induced by voice coil 106. The force experienced by center magnet 208 and ring magnet 210 cause these components to be displaced in the z-direction. By virtue of their respective connections, back plate 206, front center plate 212, front ring plate 214, and bucking magnet 218 are displaced in the z-direction during operation of actuator assembly 100.
Bucking magnet 218 is provided to focus the magnetic field generated by center magnet 208 and ring magnet 210, so that the magnetic flux passing though voice coil 106 along the x-axis is maximized. The polarity of bucking magnet 218 is chosen to oppose the magnetic flux of center magnet 208 and ring magnet 210. That is, center magnet 208 and bucking magnet 218 have their corresponding magnetic poles aligned in opposite directions. Bucking magnet 218 can also reduce the stray magnetic flux generated by center magnet 208 and ring magnet 210, e.g., reduce the magnetic flux that does not pass perpendicularly to voice coil 106.
During normal operation of actuator module 100, moving components of the actuator are displaced primarily in the z-direction. Outside of normal operation, the moving components of the module may be displaced in the x or y-directions, e.g., as a result of the module being dropped, or as a result of a mobile device that includes the module being dropped. Displacement in the x or y-directions of the moving components can cause damage to actuator module 100. Accordingly, hood 102 and frame 204 serve as physical stops to prevent significant displacement of the moving components of actuator module 100.
For example, when actuator module 100 is dropped, back plate 206, front ring plate 214, or both may contact frame 204, preventing further displacement of these components in the x or y-directions. Back plate 206 and front ring plate 214 can be made from one or more materials that are able to withstand the shock caused by contacting frame 204. These components are also sized to prevent ring magnet 210 from contacting frame 204, therefore preventing the magnet from being damaged as a result of contacting the frame. For example, a section of the outer surface formed by ring magnet 210 is recessed relative to a section of the outer surface formed by front ring plate 214. Similarly, a section of the output surface formed by ring magnet 210 is recessed relative to a section of the outer surface formed by back plate 206. One of the recessed portions of ring magnet 210 is accented by a white dotted line 404. In other words, a first gap between an inner surface of frame 204 and the outer surface of front ring plate 214 and a second gap between the inner surface of frame 204 and an outer surface of back plate 206 are smaller than a third gap between the inner surface of the frame and the outer surface of ring magnet 210. For example, the difference between the first and third gaps and the second and third gaps can be about 0.05 mm or less (e.g., 0.045 mm or less, 0.04 mm or less, 0.035 mm or less).
Similarly, to protect ring magnet 210, a section of the inner surface formed by the ring magnet is recessed relative to a section of the inner surface of front ring plate 214. One of the recessed portions of ring magnet 210 is accented by a white dotted line 406. In other words, a gap between voice coil 106 and front ring plate 214 is smaller than a gap between the voice coil and ring magnet 210. This relative spacing prevents ring magnet 210 from contacting voice coil 106.
Similarly, to protect center magnet 208, a section of the outer surface formed by the center magnet is recessed relative to a section of the outer surface formed by front center plate 212. One of the recessed portions of center magnet 208 is accented by a white dotted line 408. In other words, a gap between voice coil 106 and front center plate 212 is smaller than a gap between voice coil 106 and center magnet 208. This relative spacing prevents center magnet 208 from contacting voice coil 106.
The relative shape of other components of actuator module 100 can be chosen to prevent damage that may be caused by the module being dropped. For example, back plate 206 can be shaped so as to efficiently dissipate the forces generated when actuator module 100 is dropped.
Referring to
Concentric corners can nest within one another, allowing a greater surface area of contact between the corners, as compared to the surface area of contact between corners that are not concentric. Accordingly, the corresponding corners of voice coil 106, front center plate 212, and front ring magnet 214 are concentric with respect to one another.
Similarly, the shapes of the corners of other components of actuator module 100 can be chosen so that the corners that may contact one another when the module is dropped have a large enough surface area to effectively dissipate forces generated during the drop.
To further help maximize the contacting surface area between voice coil 106 and front ring plate 214 during displacement in the x and/or y-directions, a distance between the outside corner arc of voice coil 106 and the inside corner arc of front ring plate 214 is larger than a distance between the outside middle edge of the voice coil and the inside middle edge of the front ring plate. Similarly, a distance between the outside corner arc of front center plate 212 and the inside corner arc of voice coil 106 is larger than a distance, between the outside middle edge of the front center plate and the inside middle edge of the voice coil.
In some embodiments, actuator module 100 can include a damping material between all or some of the edges of components that may make contact with one another, e.g., if actuator module 100 is dropped. For example, a damping material can be positioned between an inner edge 502 of frame 204 and an outer edge 504 of back plate 206. In some embodiments, a damping material can be placed between inner edge 410 of front ring plate 214 and outer edge 420 of voice coil 106. In other embodiments, a damping material can be placed between inner edge 422 of voice coil 106 and outer edge 430 of front center plate 212.
In some embodiments, a damping material can be attached to one or more springs of the motor module to form a composite spring. For example, a damping material can be attached above or below the spring, or can be attached both above and below the spring. The damping material can be completely or partially coplanar with one or more surfaces of the spring. In some embodiments, the placement of the damping material can be chosen such that the properties of the spring are different from those of the resulting composite spring. For example, adding a damping material to a spring can form a composite spring having a different stiffness or frequency response (e.g., different fundamental, rocking, and/or shearing frequency) than the spring alone.
In some embodiments, a damping material can be positioned between a top surface of back plate 206 and a bottom surface of hood 102. In other embodiments, a damping material can be positioned between hood 102 and frame 204. The damping material can be any material that is able to reduce the force of impact between components that contact one another. For example, the damping material can be a foam, a pressure sensitive adhesive, a ferrofluid, or a compliant polymer, e.g., one having a low stiffness and high elongation after curing.
The components of actuator module 100 are packaged together, as illustrated in
In addition to serving as an enclosure for the other components of actuator module 100, hood 102 also provides magnetic shielding. When actuator module 100 is housed in a mobile device, it is advantageous to reduce the magnetic flux present outside of hood 102, e.g., so that other electronic components of the mobile device are not affected by the magnetic fields generated by the magnets and voice coil 106. Accordingly, the material properties of hood 102 are chosen to provide the desired magnetic shielding. For example, the magnetic permeability of the one or more materials chosen for hood 102 should be high enough so that the hood acts as a shield, but not so high that the hood promotes the formation of magnetic fields that may be present as a result of other components housed in the mobile device. For example, the material or materials of hood 102 may have a relative permeability equal to or more than 100, equal to or more than 1000, or equal to or more than 10000. Examples include high carbon steel and vanadium permendur.
While the foregoing figures cover a specific embodiment of an actuator module, i.e., actuator module 100, more generally the principles embodied in this example can be applied in other designs too. For example, while magnet motor 104 has a substantially square footprint (i.e., in the x-y plane), other shapes are possible, such as substantially rectangular, oval, or round.
While actuator module 100 includes three magnets, in some implementations, an actuator module can include one, two, three, or more magnets. For example, while actuator module 100 includes ring magnet 210 and center magnet 208, in some embodiments, an actuator module can include either the ring magnet or the center magnet and one or more bucking magnets. In other embodiments, an actuator module can include either ring magnet 210 or center magnet 208 and no bucking magnet 218.
In some embodiments, an actuator module can include a cup magnet module, e.g., a magnet positioned in a cup made of a permeable material, such as steel. In some embodiments, the cup magnet module can be accompanied by one or more bucking magnets, while in other embodiments, an actuator module can include the cup magnet module and no bucking magnet.
In some embodiments, an actuator module can include a ring magnet, a yoke, and no bucking magnet. In other embodiments, an actuator module can include a ring magnet, a yoke, and one or more bucking magnets.
In some embodiments, the actuator module can include one or more radially magnetized magnets accompanied by zero, one, or more bucking magnets.
The magnets of actuator module 100 can be an iron magnet, a neodymium magnet, or a ferrite magnet, such as one composed of iron and nickel. In some embodiments, one or more of the magnets of actuator module 100 can be replaced by an electromagnet. In some embodiments, actuator module 100 can include high permeability materials.
In general, the relative polarities of the magnets, as shown with respect to
In general, the actuator modules described above can be used in a variety of applications. For example, in some embodiments, actuator module 100 can be used to drive a panel of a panel audio loudspeaker, such as a distributed mode loudspeaker (DML). Such loudspeakers can be integrated into a mobile device, such as a mobile phone. For example, referring to
Mobile device 700 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 distributed mode actuator, or DMA. The actuator is a movable component arranged to provide a force to a panel, such as touch panel display 704, causing the panel to vibrate. The vibrating panel generates human-audible sound waves, e.g., in the range of 20 Hz to 20 kHz.
In addition to producing sound output, mobile device 700 can also produce haptic output using the actuator. For example, the haptic output can correspond to vibrations in the range of 180 Hz to 300 Hz.
In general, the disclosed actuators are controlled by an electronic control module, e.g., electronic control module 820 in
Processor 910 may be implemented as any electronic device capable of processing, receiving, or transmitting data or instructions. For example, processor 910 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 920 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 930, signal generator 940, one or more components of I/O module 950, one or more communication channels accessible via network/communications module 960, one or more sensors (e.g., biometric sensors, temperature sensors, accelerometers, optical sensors, barometric sensors, moisture sensors and so on), and/or actuator module 100.
Signal generator 940 is configured to produce AC waveforms of varying amplitudes, frequency, and/or pulse profiles suitable for actuator module 100 and producing acoustic and/or haptic responses via the actuator. Although depicted as a separate component, in some embodiments, signal generator 940 can be part of processor 910. In some embodiments, signal generator 940 can include an amplifier, e.g., as an integral or separate component thereof.
Memory 920 can store electronic data that can be used by the mobile device. For example, memory 920 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 920 may also store instructions for recreating the various types of waveforms that may be used by signal generator 940 to generate signals for actuator module 100. Memory 920 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 900 may include various input and output components represented in
Each of the components of I/O module 950 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 960 includes one or more communication channels. These communication channels can include one or more wireless interfaces that provide communications between processor 910 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 910. 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 960 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 mobile device 700 to a mobile phone for output on that device and vice versa. Similarly, the network/communications module 960 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.
The actuator technology disclosed herein can be used in panel audio systems, e.g., designed to provide acoustic and/or haptic feedback. The panel may be a display system, for example based on OLED of LCD technology. The panel may be part of a smartphone, tablet computer, or wearable devices (e.g., smartwatch or head-mounted device, such as smart glasses).
Other embodiments are in the following claims.
This application is a continuation of pending U.S. application Ser. No. 17/626,861, filed Jan. 13, 2022, which is a U.S. National Stage application, and claims priority of International Application No. PCT/US2020/043238, filed Jul. 23, 2020, which claims the benefit of U.S. Application No. 62/894,636, filed Aug. 30, 2019, which is incorporated by reference in its entirety.
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| Number | Date | Country | |
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| 20240129672 A1 | Apr 2024 | US |
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| Number | Date | Country | |
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| Parent | 17626861 | US | |
| Child | 18500835 | US |
