U.S. patent application number 16/422366 was filed with the patent office on 2019-12-19 for generation and braking of vibrations.
The applicant listed for this patent is Immersion Corporation. Invention is credited to Juan Manuel CRUZ-HERNANDEZ, Danny A. GRANT, Vahid KHOSHKAVA, Christopher ULLRICH.
Application Number | 20190385422 16/422366 |
Document ID | / |
Family ID | 66676991 |
Filed Date | 2019-12-19 |
United States Patent
Application |
20190385422 |
Kind Code |
A1 |
CRUZ-HERNANDEZ; Juan Manuel ;
et al. |
December 19, 2019 |
GENERATION AND BRAKING OF VIBRATIONS
Abstract
An actuator system configured to generate a haptic effect, the
actuator system including a housing of an electronic device, the
housing being configured to form a mechanical ground, a first
actuator disposed between a first moving mass and the mechanical
ground, the first actuator being configured to render the haptic
effect, and a second actuator disposed between a second moving mass
and the mechanical ground, the second actuator being configured to
dampen the haptic effect.
Inventors: |
CRUZ-HERNANDEZ; Juan Manuel;
(Westmount, CA) ; GRANT; Danny A.; (Laval, CA)
; KHOSHKAVA; Vahid; (Laval, CA) ; ULLRICH;
Christopher; (Ventura, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Immersion Corporation |
San Jose |
CA |
US |
|
|
Family ID: |
66676991 |
Appl. No.: |
16/422366 |
Filed: |
May 24, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
16010372 |
Jun 15, 2018 |
10395489 |
|
|
16422366 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 3/0414 20130101;
G06F 3/016 20130101; G08B 6/00 20130101 |
International
Class: |
G08B 6/00 20060101
G08B006/00; G06F 3/041 20060101 G06F003/041 |
Claims
1. An actuator system configured to control a haptic effect, the
actuator system comprising: a first actuator disposed between a
first moving mass and a device housing, the first actuator being
configured to render the haptic effect; and a second actuator
disposed between a second moving mass and the device housing, the
second actuator being configured to generate a braking force tuned
to dampen the haptic effect.
2. The actuator system of claim 1, wherein the device housing is
mechanically coupled to a band of a wearable device, and wherein
the device housing and said band act in cooperation to jointly
render vibrations.
3. The actuator system according to claim 1, wherein a size of the
second moving mass is calibrated to generate the braking force
according to a resonant frequency of the first actuator so as to
dampen the haptic effect generated by the first actuator.
4. The actuator system according to claim 1, wherein each of the
first actuator and the second actuator is driven by one of a
closed-loop drive circuit or an open-loop drive circuit.
5. The actuator system according to claim 4, wherein the second
actuator is configured as a sensor for the closed-loop drive
circuit.
6. The actuator system according to claim 1, further comprising: a
sensor that is configured to monitor vibration after rendering the
haptic effect.
7. The actuator system according to claim 1, wherein the first
actuator has a first resonant frequency and the second actuator has
a second resonant frequency.
8. The actuator system according to claim 7, wherein the second
resonant frequency is calibrated to eliminate vibrations of the
haptic effect within 5 ms.
9. An actuator system configured to control a haptic effect, the
actuator system comprising: a housing of an electronic device, the
housing being configured to form a mechanical ground; and an
actuator comprising a piezoelectric moving mass mechanically
coupled to a spring and configured to operate in first and second
movement states, wherein in said first movement state, said
piezoelectric moving mass is configured to be driven by said spring
unencumbered by said mechanical ground to render the haptic effect,
and wherein in said second movement state, said piezoelectric
moving mass is configured to expand so as to cause contact friction
with said mechanical ground to dampen the haptic effect.
10. The actuator system of claim 9, wherein the device housing is
mechanically coupled to a band of a wearable device, and wherein
said device housing and said band act in cooperation to jointly
render vibrations.
11. The actuator system according to claim 9, wherein said spring
is not driven in said second movement state.
12. The actuator system according to claim 9, wherein said
piezoelectric moving mass comprises a plurality of piezoelectric
actuators.
13. The actuator system according to claim 12, wherein said
plurality of piezoelectric actuators are disposed along an axis of
said housing.
14. An actuator system configured to control a haptic effect, the
actuator system comprising: a housing of an electronic device, the
housing being configured to provide a mechanical ground; and an
actuator comprising a moving mass mechanically coupled to a
piezoelectric spring, wherein the actuator system is configured to
operate in first and second movement states, wherein in said first
movement state, said moving mass is configured to be driven to
render the haptic effect, and said piezoelectric spring has a first
stiffness, and wherein in said second movement state, said
piezoelectric spring is configured to have a second stiffness which
encumbers movement of said moving mass to dampen the haptic
effect.
15. The actuator system of claim 14, wherein the device housing is
mechanically coupled to a band of a wearable device, and wherein
said device housing and said band act in cooperation to jointly
render vibrations.
16. The actuator system according to claim 14, wherein in said
first movement state, said moving mass is configured to be driven
by a magnetic field.
17. The actuator system according to claim 16, wherein said moving
mass is not driven by said magnetic field in said second movement
state.
18. The actuator system according to claim 14, wherein in said
first movement state, said moving mass is configured to be driven
by said piezoelectric spring.
19. The actuator system according to claim 14, wherein in said
second movement state, said moving mass is configured to expand so
as to cause contact friction with said mechanical ground to dampen
the haptic effect.
20. The actuator system according to claim 14, wherein said second
stiffness of the piezoelectric spring is calibrated to dampen the
haptic effect according to a resonant frequency of the actuator.
Description
PRIORITY APPLICATION
[0001] This application is a continuation of U.S. patent
application Ser. No. 16/010,372, filed on Jun. 15, 2018, which has
been incorporated herein by reference in its entirety.
FIELD OF INVENTION
[0002] The embodiments of the present invention are generally
directed to electronic devices, and more particularly, to
electronic devices that produce haptic effects.
BACKGROUND
[0003] Electronic device manufacturers strive to produce a rich
interface for users. Conventional devices use visual and auditory
cues to provide feedback to a user. In some interface devices,
kinesthetic feedback (e.g., active and resistive force feedback)
and/or tactile feedback (e.g., vibration, texture, and heat) is
also provided to the user, more generally known collectively as
"haptic feedback" or "haptic effects." Haptic feedback can provide
cues that enhance and simplify the user interface. Specifically,
vibration effects, or vibrotactile haptic effects, may be useful in
providing cues to users of electronic devices to alert the user to
specific events, or provide realistic feedback to create greater
sensory immersion within a simulated or virtual environment.
[0004] With the continued development of mobile devices, such as
smart phones and tablets, users are now able to view high
definition audio and video on a handheld device that traditionally
could only be seen in movie theaters, television or home theater
systems. With haptically-enabled mobile devices, experience has
shown that content viewing is sufficiently enhanced, and viewers
like it, if there is a haptic content component in addition to the
audio and video content components. However, in order to be
compatible with the high definition audio/video, for example,
crisper haptic effects are needed, and provided herein.
SUMMARY OF THE INVENTION
[0005] Embodiments of the present invention are directed toward
electronic devices configured to produce haptic effects that
substantially improve upon the related art.
[0006] Features and advantages of the embodiments are set forth in
the description which follows, or will be apparent from the
description, or may be learned by practice of the invention.
[0007] In one example, an actuator system is configured to generate
a haptic effect, such as a crisp haptic effect. The actuator system
includes a housing of an electronic device, the housing being
configured to form a mechanical ground, a first actuator disposed
between a first moving mass and the mechanical ground, the first
actuator being configured to render the haptic effect, and a second
actuator disposed between a second moving mass and the mechanical
ground, the second actuator being configured to dampen the haptic
effect.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Further embodiments, details, advantages, and modifications
will become apparent from the following detailed description of the
preferred embodiments, which is to be taken in conjunction with the
accompanying drawings.
[0009] FIG. 1 is a block diagram of a haptically-enabled
system/device according to an example embodiment of the present
invention.
[0010] FIG. 2 illustrates a multi-actuator system for generating
crisp haptic effects according to an example embodiment of the
present invention.
[0011] FIG. 3 illustrates an actuator system for generating crisp
haptic effects according to an example embodiment of the present
invention.
[0012] FIG. 4 illustrates an actuator system for generating crisp
haptic effects according to another example embodiment of the
present invention.
DETAILED DESCRIPTION
[0013] Reference will now be made in detail to the embodiments,
examples of which are illustrated by the accompanying drawings. In
the following detailed description, numerous specific details are
set forth in order to provide a thorough understanding of the
present invention. However, it will be apparent to one of ordinary
skill in the art that the present invention may be practiced
without these specific details. In other instances, well-known
methods, procedures, components, and circuits have not been
described in detail so as not to unnecessarily obscure aspects of
the embodiments. Wherever possible, like reference numbers will be
used for like elements.
[0014] The example embodiments are generally directed toward
improved haptic systems. In the various embodiments, a single or
multi-actuator system is configured to generate "crisp" haptic
(vibrotactile) effects. In particular, the single and
multi-actuator embodiments described herein are configured to
dampen or cancel undesired vibrations that occur after the
rendering of one or more haptic effects. For example, a first
actuator may be configured to generate haptic effects and a second
actuator may be configured to dampen or cancel the remaining or
residual vibrations after the rendering of the haptic effect. In
another example embodiment, a piezoelectric actuator may comprise a
moving mass, and be configured to brake the movement of the
actuator. In another example embodiment, an electromagnetically
driven moving mass is provided on a piezo spring (also referred to
as a "leaf spring" or "piezo beam"). The piezo spring acts as a
spring for the moving mass and also may be activated to stop the
moving mass, thereby acting as a braking mechanism.
[0015] FIG. 1 is a block diagram of a haptically-enabled
system/device 10 according to an example embodiment of the present
invention. System 10 includes a touch sensitive surface 11 or other
type of user interface mounted within a housing 15, and may include
mechanical keys/buttons 13.
[0016] Internal to system 10 is a haptic feedback system that
generates haptic effects on system 10 and includes a processor or
controller 12. Coupled to processor 12 is a memory 20, and a haptic
drive circuit 16 which is coupled to an actuator 18. Processor 12
may be any type of general purpose processor, or could be a
processor specifically designed to provide haptic effects, such as
an application-specific integrated circuit ("ASIC"). Processor 12
may be the same processor that operates the entire system 10, or
may be a separate processor. Processor 12 can decide what haptic
effects are to be played and the order in which the effects are
played based on high level parameters. In general, the high level
parameters that define a particular haptic effect include
magnitude, frequency and duration. Low level parameters such as
streaming motor commands could also be used to determine a
particular haptic effect. A haptic effect may be considered
"dynamic" if it includes some variation of these parameters when
the haptic effect is generated or a variation of these parameters
based on a user's interaction. The haptic feedback system in one
embodiment generates vibrations 30, 31 or other types of haptic
effects on system 10.
[0017] Processor 12 outputs the control signals to haptic drive
circuit 16, which includes electronic components and circuitry used
to supply actuator 18 with the required electrical current and
voltage (i.e., "motor signals") to cause the desired haptic
effects. System 10 may include more than one actuator 18, and each
actuator 18 may include a separate drive circuit 16, all coupled to
a common processor 12.
[0018] Haptic drive circuit 16 is configured to generate one or
more haptic drive signals. For example, the haptic drive signal may
be generated at and around the resonance frequency (e.g., +/-20 Hz,
30 Hz, 40 Hz, etc.) of actuator 16. In certain embodiments, haptic
drive circuit 16 may comprise a variety of signal processing
stages, each stage defining a subset of the signal processing
stages applied to generate the haptic command signal.
[0019] Non-transitory memory 20 may include a variety of
computer-readable media that may be accessed by processor 12. In
the various embodiments, memory 20 and other memory devices
described herein may include a volatile and nonvolatile medium,
removable and non-removable medium. For example, memory 20 may
include any combination of random access memory ("RAM"), dynamic
RAM ("DRAM"), static RAM ("SRAM"), read only memory ("ROM"), flash
memory, cache memory, and/or any other type of non-transitory
computer-readable medium. Memory 20 stores instructions executed by
processor 12. Among the instructions, memory 20 includes audio
haptic simulation module 22, which are instructions that, when
executed by processor 12, generates high bandwidth haptic effects
using speaker 28 and actuator 18, as disclosed in more detail
below. Memory 20 may also be located internal to processor 12, or
any combination of internal and external memory.
[0020] System 10 may be any type of handheld/mobile device, such as
a cellular telephone, personal digital assistant ("PDA"),
smartphone, computer tablet, gaming console, controller or split
controller, remote control, or any other type of device that
includes a haptic effect system that includes one or more
actuators. System 10 may be a wearable device such as wrist bands,
headbands, eyeglasses, rings, leg bands, arrays integrated into
clothing, etc., or any other type of device that a user may wear on
a body or can be held by a user and that is haptically enabled,
including furniture or a vehicle steering wheel. Further, some of
the elements or functionality of system 10 may be remotely located
or may be implemented by another device that is in communication
with the remaining elements of system 10.
[0021] Actuator 18 may be any type of actuator or haptic output
device that can generate a haptic effect. In general, an actuator
is an example of a haptic output device, where a haptic output
device is a device configured to output haptic effects, such as
vibrotactile haptic effects, electrostatic friction haptic effects,
temperature variation, and/or deformation haptic effects, in
response to a drive signal. Although the term actuator may be used
throughout the detailed description, the embodiments of the
invention may be readily applied to a variety of haptic output
devices. Actuator 18 may be, for example, an electric motor, an
electro-magnetic actuator, a voice coil, a shape memory alloy, an
electro-active polymer, a solenoid, an eccentric rotating mass
motor ("ERM"), a harmonic ERM motor ("HERM"), a linear resonance
actuator ("LRA"), a solenoid resonance actuator ("SRA"), a
piezoelectric actuator, a macro fiber composite ("MFC") actuator, a
high bandwidth actuator, an electroactive polymer ("EAP") actuator,
an electrostatic friction display, an ultrasonic vibration
generator, or the like. In some instances, the actuator itself may
include a haptic drive circuit. In the description that follows, a
piezoelectric actuator may be used as an example, but it should be
understood that the embodiments of the present invention may be
readily applied to any type of actuator or haptic output
device.
[0022] Currently, there is a high degree of variance between
similarly rated actuators. As a result, the similarly rated
actuators often produce inconsistent haptic responses. The variance
is especially large between different actuator manufacturers, but
is still significant among actuators produced by a single
manufacturer. Variance between similarly rated actuators is
especially perceptible for the generation of "crisp" haptic
effects.
[0023] Crisp haptic effects include short duration haptic effects
(e.g., 5 ms) that reach a relatively high or peak acceleration
value (e.g., 2.5 peak to peak gravities "Gpp", or 3.5 Gpp). In
other words, during the generation of a crisp haptic effect, the
actuator may reach a high or peak acceleration in less than one
cycle. In addition, the actuator returns to a stopped position
within 5 ms after drive signal is removed. For a crisp haptic
effect, minimal (e.g., imperceptible) or no vibrations remain after
rendering the effect regardless of the driving frequency of the
actuator.
[0024] Generation of high acceleration haptic effects within 5 ms
generally uses an actuator that generates vibrations in the range
of 100 Hz and over. For example, a single oscillation to drive a
haptic effect may have duration of 10 ms, and thus, by the
mid-point of the driving signal, that is 5 ms, the acceleration is
already high.
[0025] The generation of crisp haptic effects is subject to
numerous drawbacks. The generation of crisp haptic effects is
difficult to achieve using some electromechanical actuators (e.g.,
LRA and ERM). Also, some known techniques at most function with
high resonant systems and are unable to produce high acceleration
values in a short duration (e.g., 5 ms). Other known techniques
attempt to modify the haptic drive signal by using a closed-loop
haptic drive circuit. Such known drive circuits have been adapted
to produce "crisp" haptic effects. However, such techniques are
overly complex and costly due to the incorporation of expensive
sensors.
[0026] FIG. 2 illustrates a multi-actuator system 200 for
generating crisp haptic effects according to an example embodiment
of the present invention.
[0027] As illustrated in FIG. 2, multi-actuator system 200 includes
a first piezoelectric actuator 218A and a second piezoelectric
actuator 2186. Each of first and second piezoelectric actuators
218A, 218B is disposed between, and coupled to, a mechanical ground
215 and a respective moving mass. In this example configuration,
first piezoelectric actuator 218A is coupled to first moving mass
219A and second piezoelectric actuator 2186 is coupled to second
moving mass 2196. The multi-actuator system 200, including first
and second piezoelectric actuators 218A, 218B, is configured to
generate one or more haptic effects, including crisp haptic
effects.
[0028] In multi-actuator system 200, the embodiments may rely upon
first piezoelectric actuator 218A to generate one or more haptic
effects and may further rely upon second piezoelectric actuator
218B for vibration dampening/cancellation, or vice versa. In an
alternative configuration, both of first and second piezoelectric
actuators 218A, 218B may be configured to produce one or more
haptic effects, and the motion of both first and second
piezoelectric actuators 218A, 218B may be inverted to generate a
braking signal and/or braking force that is tuned for vibration
dampening/cancellation.
[0029] To stop a haptic effect, such as in the production of a
crisp haptic effect, remaining or residual oscillations of the
haptic effect are removed. Such remaining vibrations may also be
referred to as a "vibrations tail."
[0030] In the various embodiments, first and second piezoelectric
actuators 218A, 218B may be driven using known or expected open- or
closed-loop drive circuits. When using a closed-loop drive circuit,
second piezoelectric actuator 218B may be further configured as a
sensor for the closed-loop control process. By configuring an
actuator, such as second piezoelectric actuator 218B, as the sensor
for a closed-loop drive circuit, the cost associated with a
dedicated sensor is avoided. Here, one actuator generates one or
more haptic effects. And, the other actuator is configured as both
a sensor to monitor the remaining vibrations of the one or more
haptic effects and to apply a braking signal or force to remove
undesired vibrations. In other configurations, the remaining
vibrations may be detected using a dedicated sensor. The dedicated
sensor may be engaged to monitor vibrations after the processing of
the haptic drive signal. Dedicated sensors may be used in
connection with actuator types that cannot be configured as a
sensor.
[0031] First and second moving masses 219A, 219B may be standalone
components or may comprise, or be otherwise coupled to, other
components of the host electronic device, such as a push button,
rotatable knob, screen, touchscreen, digital crown, and the like.
Additionally, or alternatively, first and second moving masses
219A, 2198 may have the same or different sizes (e.g., the mass of
219A may be greater than, less than, or equal to the mass of 219B).
More importantly, the moving mass corresponding to the actuator
used for vibration dampening/cancellation are calibrated or tuned
to quickly eliminate any undesired vibrations that remain after the
rendering of the haptic effect. For example, the size of the moving
mass may be determined according to the frequency of the vibrations
tail.
[0032] Mechanical ground 215 may be the housing of the host
electronic device, such as housing 15 of FIG. 1. Although
mechanical ground 215 is depicted as a single element, multiple
mechanically coupled elements may collectively form mechanical
ground 215. For example, the touchscreen and housing of a
smartphone may collectively form mechanical ground 215. Here, the
touchscreen and the housing are mechanically coupled and may
jointly render vibrations. In another example, the housing and band
of a wearable device may collectively form mechanical ground 215.
Here again, the housing and band are mechanically coupled and may
jointly render vibrations. In the example configuration depicted in
FIG. 2, first and second piezoelectric actuators 218A, 218B have
respective displacements d1, d2 in the same direction. However,
depending on the configuration of first and second moving masses
219A, 2198 as well as mechanical ground 215, the respective
displacements d1, d2 may vary.
[0033] Although a piezoelectric actuator is described in this
example embodiment, any type of actuator or haptic output device
may be used. Haptic output devices may include any haptic output
device, such as the various haptic output devices described in
connection with actuator 18 of FIG. 1. In configurations using
haptic output devices other than piezoelectric actuators, a
dedicated sensor may be used in combination with the second
actuator. Alternatively, piezoelectric actuators may be configured
to function as both an actuator and a sensor. Piezoelectric
actuators and dedicated sensor may be configured to continually or
periodically monitor the vibrations output by actuator 218, and the
sensed vibrations may be applied as a closed-loop feedback signal
in a haptic drive circuit. The sensor may be mounted on the
piezoelectric actuator itself (e.g., a strain gauge), or the sensor
may be mounted on the body of the host electronic device (e.g., an
accelerometer).
[0034] Additionally, or alternatively, first and second
piezoelectric actuators 218A, 2188 may be configured to have the
same or different resonant frequencies. The resonant frequency
first piezoelectric actuator 218A may be greater than, less than,
or equal to the resonant frequency of second piezoelectric actuator
2188. More importantly, the resonant frequency of the actuator(s)
used for vibration dampening/cancellation are calibrated or tuned
to quickly eliminate any undesired vibrations that remain after the
rendering of the haptic effect.
[0035] FIG. 3 illustrates an actuator system 300 for generating
crisp haptic effects according to an example embodiment of the
present invention. As illustrated in FIG. 3, actuator system 300
includes a mechanical ground 315, a piezoelectric moving mass 318
which includes, or is formed of, one or more piezoelectric
actuators, and a spring 324.
[0036] In some actuator types, such as the LRA type actuator, a
moving mass is typically mounted on an electromechanical part, such
as a spring 324. In this embodiment, a piezoelectric moving mass
318 is introduced. Piezoelectric moving mass 318 includes, or is
formed of, one or more piezoelectric actuators. In other words,
piezoelectric actuators may either be added to the moving mass, or
alternatively, may comprise the moving mass. As illustrated in FIG.
3, example actuator system 300 includes two states. The two states
of actuator system 300 will now be described.
[0037] When one or more haptic effects are being rendered, the
piezoelectric moving mass 318, illustrated as 318A, is in an "Off"
state. In other words, piezoelectric moving mass 318 is not
engaged. Accordingly, piezoelectric moving mass 318A is configured
to be driven by spring 324, illustrated as 324A, such that the
haptic effects may be rendered. Here, movement of piezoelectric
moving mass 318A is not encumbered by mechanical ground 315,
illustrated as 315A.
[0038] However, when activating braking, piezoelectric moving mass
318 is engaged and configured to expand. In this "On" state,
piezoelectric moving mass 318, illustrated as 318B, expands and
causes friction with an adjacent part, such as mechanical ground
315, illustrated as 3156. As a result of the expansion of
piezoelectric moving mass 3186, the vibrations of the actuator are
dampened/cancelled. Additionally, during braking, the
electromechanical components, such as spring 324B, are
deactivated.
[0039] Mechanical ground 315 may be the housing of the host
electronic device, such as housing 15 of FIG. 1. Although
mechanical ground 315 is depicted as a single element, multiple
mechanically coupled elements may collectively form mechanical
ground 315.
[0040] Although FIG. 3 illustrates an example configuration of a
single-actuator system, numerous other configurations may be
readily configured. For example, one or more piezoelectric
actuators may be coupled to a piezoelectric moving mass. In another
example, one or more piezoelectric actuators may be coupled to a
traditional moving mass. In either configuration, the inclusion of
multiple piezoelectric actuators on the moving mass may be
configured to further increase friction and to more quickly stop
the moving mass. In other example configurations, the actuators may
be disposed along any axis of the host electronic device (e.g.,
opposite or adjacent portions of the housing). The various haptic
output devices of actuator system 300 may be driven by an open- or
closed-loop drive circuit.
[0041] FIG. 4 illustrates an actuator system 400 for generating
crisp haptic effects according to another example embodiment of the
present invention. As illustrated in FIG. 4, actuator system 400
includes a mechanical ground 415, a moving mass 418, and a
piezoelectric spring 424 (also referred to as a "leaf spring" or
"piezo beam").
[0042] To render one or more haptic effects, moving mass 418 is
driven by a magnetic field (not shown) to induce movement of moving
mass 418 and to cause vibration. As compared to the embodiments of
FIG. 3, in which piezoelectric moving mass 318 is
electromechanically driven by spring 324, moving mass 418 is
electromagnetically driven along a piezoelectric material, such as
piezoelectric spring 424. In the various embodiments, piezoelectric
spring 424 is an active spring and comprises the actuator.
[0043] When one or more haptic effects are being rendered, moving
mass 418 is driven to move and to produce vibrations. Here, motion
of moving mass 418 is not encumbered by piezoelectric spring 424.
However, when activating braking, piezoelectric spring 424 is
engaged. In some instances, the stiffness of piezoelectric spring
424 may be calibrated or tuned according to the resonant frequency
of the actuator. Alternatively, or additionally, piezoelectric
spring 424 may cause moving mass 418 to a stop position at either
end of piezoelectric spring 424. In another example, piezoelectric
spring 424 may be configured to expand. Expansion of piezoelectric
spring 424 causes friction with moving mass 418. Here, expansion of
piezoelectric spring 424 induces friction between moving mass 418
and mechanical ground 415. As a result of the expansion of
piezoelectric spring 424, the vibrations of the actuator are
dampened/cancelled. Additionally, during braking, the magnetic
field that drives moving mass 418 is deactivated.
[0044] In some embodiments, piezoelectric spring 424 is activated
at the end or near to the end of the haptic effect. In one example,
for a 10 ms haptic effect, at the end of the haptic effect or at
time duration of 9.8 ms, piezoelectric spring 424 may be activated
to cancel/dampen the vibrations of moving mass 418. As the free
oscillation frequency is known, piezoelectric spring 424 can be
activated at, or otherwise tuned to, that frequency (e.g., out of
phase with the free oscillation frequency) to cancel/dampen any
remaining vibrations. In another example, moving mass 418 is driven
with an electromagnetic field, and when the desired haptic effect
is finished (e.g., at time duration of 10 ms), piezoelectric spring
424 can be activated to counterbalance the movement of moving mass
418.
[0045] In yet another example, a bimorph structure may be used.
Here, two piezoelectric actuators may be bonded with the same
working mechanism on a passive spring. One piezoelectric actuator
drives the moving mass, and the other piezoelectric actuator is
engaged when braking is needed. In other words, a second
piezoelectric actuator can cancel the haptic effect(s) of the first
piezoelectric actuator.
[0046] Mechanical ground 415 may be the housing of the host
electronic device, such as housing 15 of FIG. 1. Although
mechanical ground 415 is depicted as a single element, multiple
mechanically coupled elements may collectively form mechanical
ground 415.
[0047] Although FIG. 4 illustrates an example configuration of a
single-actuator system, numerous other configurations may be
readily configured. For example, one or more piezoelectric
actuators comprise the moving mass. In another example, one or more
piezoelectric actuators may be coupled to a traditional moving
mass. In either configuration, the inclusion of multiple
piezoelectric actuators on the moving mass may be configured to
more quickly stop the moving mass. In other example configurations,
the piezoelectric spring may be configured to both further drive
the moving mass by varying the stiffness of the piezoelectric
spring (e.g., add force, speed, etc) as well as cause braking as
described above. The various haptic output devices of actuator
system 400 may be driven by an open- or closed-loop drive
circuit.
[0048] In the various embodiments discussed above, single and
multi-actuator systems are configured to generate crisp haptic
effects. The single and multi-actuator embodiments described herein
are configured to dampen/cancel undesired vibrations that occur
after the rendering of one or more haptic effects.
[0049] One having ordinary skill in the art will readily understand
that the invention as discussed above may be practiced with steps
in a different order, and/or with elements in configurations which
are different than those which are disclosed. Additionally, one of
ordinary skill in the art will readily understand that features of
the various embodiments may be practiced in various combinations.
Therefore, although the invention has been described based upon
these preferred embodiments, it would be apparent to those of skill
in the art that certain modifications, variations, and alternative
constructions would be apparent, while remaining within the spirit
and scope of the invention. In order to determine the metes and
bounds of the invention, therefore, reference should be made to the
appended claims.
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