Patent Grant
11388531
The present invention relates generally to power-consuming medical devices, and more particularly, to smoothing power consumption of such devices.
Hearing loss, which may be due to many different causes, is generally of two types: conductive and sensorineural. Sensorineural hearing loss is due to the absence or destruction of the hair cells in the cochlea which transduce sound signals into nerve impulses. Various hearing prostheses are commercially available to provide individuals suffering from sensorineural hearing loss with the ability to perceive sound. For example, cochlear implants use an electrode array implanted in the cochlea to bypass the mechanisms of the ear. More specifically, an electrical stimulus is delivered to the auditory nerve via the electrode array, thereby causing a hearing percept.
Conductive hearing loss occurs when the normal mechanical pathways that provide sound to hair cells in the cochlea are impeded, for example, by damage to the ossicular chain or ear canal. Individuals suffering from conductive hearing loss may retain some form of residual hearing because the hair cells in the cochlea may remain undamaged.
Individuals suffering from conductive hearing loss typically receive an acoustic hearing aid. Hearing aids rely on principles of air conduction to transmit acoustic signals to the cochlea. In particular, a hearing aid typically uses a component positioned in the recipient's ear canal to amplify sound received by the device. This amplified sound reaches the cochlea causing motion of the perilymph and stimulation of the auditory nerve.
In contrast to hearing aids, certain types of hearing prostheses commonly referred to as bone conduction devices, convert a received sound into mechanical vibrations. The vibrations are transferred through the skull to the cochlea causing generation of nerve impulses, which result in the perception of the received sound. Bone conduction devices may be a suitable alternative for individuals who cannot derive sufficient benefit from acoustic hearing aids, cochlear implants, etc.
According to one aspect of the present invention, there is an active medical device, comprising: an input receiver configured to receive a frequency-varying input signal; and a functional component that reacts to the input signal and consumes power at a rate dependant on the frequency of the input signal to which the functional component reacts, wherein the device is configured to adjust one or more portions of the input signal where the functional component consumes power at a rate that is greater than that of other portions of the input signal.
According to another aspect of the invention, there is an active medical device comprising: a functional component that has a parameter-dependent power consumption profile; and a power-smoothing circuit configured to determine an intensity level of a frequency-varying input signal, and to adjust, based on the intensity level, a parameter referenced by the functional component upon which the parameter-dependent power consumption profile depends so as to selectively reduce power consumption of the functional component, wherein the functional component is operably responsive to the adjusted parameter.
According to another aspect of the invention, there is a method of reducing power consumption of an active medical device including a functional component reactive to an input signal, comprising receiving the input signal, filtering the input signal to attenuate frequencies for which the functional component consumes power at a rate that is greater than that of other frequencies, and providing the filtered input signal to the functional component such that the functional component reacts to the input signal.
According to another aspect of the invention, there is a method of operating a hearing prosthesis, comprising receiving an acoustic signal having intensity level components, generating a signal, representative of the received acoustic signal, having corresponding intensity level components, evaluating the intensity level components of the input signal, and adjusting an operating parameter of the hearing prosthesis based on the intensity level, and evoking a hearing percept based on the received acoustic signal with the hearing prosthesis at the adjusted operating parameter so as to evoke the hearing percept utilizing a reduced amount of power as compared to evoking a hearing percept based on the received acoustic signal with the hearing prosthesis without adjustment of the operating parameter.
Illustrative embodiments of the present invention are described herein with reference to the accompanying drawings, in which:
Aspects of the present invention are generally directed to reducing a rate of power consumption of a medical device, such as a bone conduction device. In one exemplary embodiment, the device consumes power at a rate that is dependant on the frequency of a frequency-varying input signal to which a functional component of the device reacts. In another exemplary embodiment, the device consumes power at a higher rate than may be necessary to attain sufficient efficacious performance. Exemplary embodiments described herein are presented in connection with a specific type of active medical device, namely a hearing prosthesis that processes received audio signals, and more specifically, a bone conduction device that mechanically stimulates the recipient to cause a hearing percept. Some embodiments of the present invention may be implemented in other hearing prostheses as well as other medical devices that react to or otherwise process frequency-varying input signals, as will now be briefly described.
Broadly speaking, active medical devices (AMDs) consume power. Some exemplary embodiments detailed herein are directed to strategies to reduce power consumption of a given AMD by adopting techniques to operate the AMD in a more energy-efficient manner based on specific characteristics of the given AMD. In some exemplary embodiments, certain frequencies within an input signal upon which operation of the AMD is based are identified as contributing more to the AMD's power consumption than other frequencies. In such embodiments, the input signal is filtered to selectively reduce (including eliminate) at least one of the more power intensive frequency components. In some exemplary embodiments, certain features of the input signal upon which operation of the AMD is based may indicate conditions for which a less than full operational capability can be sufficient in order to obtain sufficiently efficacious performance of the AMD. In such embodiments, there may be selective adjustment of one or more parameters of the AMD to temporarily adopt less than full operational capability, thereby reducing power consumption, while still providing sufficiently effective performance. Hereinafter, this is sometimes referred to as leveling.
Additional details of the above embodiments and other embodiments will be described in greater detail below. Prior to this, an exemplary medical device with which embodiments disclosed herein and variations thereof may be utilized will be briefly discussed.
In a fully functional human hearing anatomy, outer ear 1101 comprises an auricle 1105 and an ear canal 1106. A sound wave or acoustic pressure 1107 is collected by auricle 1105 and channeled into and through ear canal 1106. Disposed across the distal end of ear canal 1106 is a tympanic membrane 1104 which vibrates in response to acoustic wave 1107. This vibration is coupled to oval window or fenestra ovalis 1110 through three bones of middle ear 1102, collectively referred to as the ossicles 1111 and comprising the malleus 1112, the incus 1113 and the stapes 1114. The ossicles 1111 of middle ear 1102 serve to filter and amplify acoustic wave 1107, causing oval window 1110 to vibrate. Such vibration sets up waves of fluid motion within cochlea 1139. Such fluid motion, in turn, activates hair cells (not shown) that line the inside of cochlea 1139. Activation of the hair cells causes appropriate nerve impulses to be transferred through the spiral ganglion cells and auditory nerve 1116 to the brain (not shown), where they are perceived as sound.
Bone conduction device 1100 comprises a sound processor (not shown), an actuator (also not shown) and/or various other operational components. In operation, sound input device 1126 converts received sounds into electrical signals. These electrical signals are utilized by the sound processor to generate control signals that cause the actuator to vibrate. In other words, the actuator converts the electrical signals into mechanical vibrations for delivery to the recipient's skull.
In accordance with embodiments of the present invention, a fixation system 1162 may be used to secure implantable component 1150 to skull 1136. As described below, fixation system 1162 may include an implant at least partially embedded in the skull 1136.
In one arrangement of
In another arrangement of
In a variation of the arrangement of
Still with reference to
An exemplary embodiment of the present invention includes a functional component having a frequency-dependent power consumption profile that includes one or more resonance peaks. In an exemplary embodiment, frequency component reduction is accomplished by filtering. Such filtering may be accomplished via the use of, for example, notch filtering. In an exemplary embodiment utilizing notch filtering, respective notch center frequencies correspond to respective resonance peaks. Still further by example, in some embodiments where the profile might indicate that power consumption increases with frequency, low pass filtering is utilized.
Some embodiments may be practiced utilizing filtering that varies based upon, for example, an energy level available from a battery (or other power storage device). (Such embodiments may be practiced in combination with other techniques detailed herein.) In some such exemplary embodiments, as the available energy level from the battery decreases, filtering is performed to a greater degree than at the higher energy level. Such filtering may be accomplished by, for example, utilizing notches that can be progressively deepened as the available energy level decreases.
In another exemplary embodiment, the notch filtering can be enhanced relative to a desired frequency band. Some such embodiments rely on the phenomenon that the location of a resonance peak in the frequency spectrum can impact the likelihood (e.g., make it relatively less likely or more likely) that the input signal will contain a significant intensity (e.g., power consuming intensity) at that frequency. By way of illustrative example, a band of frequencies may have significant intensities with regard to human speech. An exemplary embodiment may address this phenomenon by utilizing a notch filter in a manner such that if a resonance peak in the profile overlaps a significant frequency band, the corresponding notch in the filter is made deeper. This may be done because, in some embodiments, some input signals are more likely than not to have a significant intensity at the resonance frequency.
In an exemplary embodiment where the AMD 100B is a hearing prosthesis (e.g., of a type that has an internal module and an external module that communicate transcutaneously, such as a cochlear implant), the transducer is the functional component and the parameter is a modulation parameter (e.g., a pulse-width control signal “PW_CTRL”), which affects the transcutaneous coupling between the external and internal modules. The intensity of the input signal (in this exemplary embodiment, an audio signal), can be monitored so as to recognize relatively quieter conditions and/or relatively louder conditions and/or recognize a change from one such condition to another such condition. With respect to an embodiment that recognizes quieter conditions, once quieter conditions are so recognized, the value of PW_CTRL may be decreased so as to reduce a duty cycle of the wireless transmission system, and thereby reduce power consumption.
The external module 102 of
As will be discussed in more detail below, the power smoothing circuit 110C includes one or more filters 166C, and/or a level controller 168C. Because of the optional presence/absence of these components, these components are represented in dashed lines.
In embodiments having one or more filters 166C, the filter(s) provide a filtered audio signal(s) to the RF modulator block 114. If these filters are not present in a given embodiment, the power smoothing circuit 110C may transfer an unfiltered audio signal(s) to the RF modulator 114. In embodiments having the level controller 168C, the level controller 168C provides an automatic level control (ALC) signal to the RF modulator 114.
Referring back to
The RF decoder and pulse generator 122 of
The pulse generator 148 can be, for example, a pulse width modulator, pulse density modulator or a sigma-delta modulator. The pulse generator 148 produces two bit streams, P1 and P2, with each bit stream being 1-bit wide. In an exemplary embodiment, the bit streams P1 and P2 are non-overlapping. The transducer driver circuit 126, for example, can be driven directly with the two bit streams, P1 and P2.
With respect to bone conduction device 110C, rather than provide a notch in the notch filter corresponding to the resonance peak observed at about 1750 Hz, a low pass filter (LPF) instead can be provided that is configured with a pass band below the approximately 1750 Hz resonance peak. Accordingly, another of the one or more active filters 166 of the DSP (again, an example implementation of the power smoothing circuit 110A) is a low pass filter tuned to have a pass band below the approximately 1750 Hz resonance peak.
As noted above, the power smoothing circuit 110C of bone conduction device 100C can be implemented as a DSP such that the one or more filters 166 can be active filters. One of the active filters 166 can be configured as a notch filter with at least one notch corresponding to at least one of the one or more peaks in the frequency response (e.g., the peaks in plot 262), of the stimulation transducer 128 and/or implantable module 104. More particularly, the magnitude of a given notch in the notch filter, in some embodiments, is inversely proportional to the magnitude of a corresponding resonance peaks in the frequency response (e.g., the plot 262). For example, a notch filter tuned to compensate for the peaks of the plot 262 of the frequency response would have at least a first notch centered at about 700 Hz and corresponding in magnitude inversely proportionally thereto, and/or may also have a second notch centered at about 1750 Hz.
Some embodiments utilizing leveling, that is, the selective adjustment of one or more parameters of the bone conduction device 100C to temporarily adopt less than full operational capability, thereby reducing power consumption, while still providing effective performance, will now be described. As will be understood from the embodiments of
More specifically, some exemplary embodiments of the level controller 168 are configured to recognize relatively quiet acoustical conditions and then adjust (by selectively reducing) a pulse width of the OOK scheme used by the RF modulator 114. This results in the level of the voltage VLL provided to the transducer driver circuit 126 by the rectification circuit 120 being selectively reduced, resulting in power smoothing.
More particularly, the level controller 168 is configured to determine a loudness level based upon the audio signal from the audio transducer 108. The level controller 168 can be configured with a first mapping, namely a loudness:pulse width PW mapping (e.g., in the form of a look-up table (LUT), an executable block of instructions, etc.) between loudness levels and values for the pulse width PW. The level controller 168 is further operable to index the loudness level into the first mapping and retrieve therefrom a corresponding value of the pulse width PW, and supply the same to the RF modulator 114.
Before discussing further specific features of the exemplary leveling embodiments, details pertaining to the underlying features of the bone conduction device 110C useful in conveying understanding of these specific features will now be discussed. Specifically, an exemplary circuit schematic of a transducer drive circuit will be described, followed by a discussion on conceptual principles underlying the use of leveling to smooth power consumption.
In
The node 454 in
If the stimulation transducer 128 is modeled to include capacitor 460, the rate at which the transducer driver circuit 126 can charge the capacitor 460 is dq(t)=i(t)dt. At higher frequencies of the audio signal (again, provided by the audio transducer 108, and upon which the control signals fed to the transducer driver circuit 126 are based), the rate of charging the capacitor 460 correspondingly increases, which may result in commensurately higher peak currents to remove or add charge more quickly from or to the plates of the capacitor 460. Consequently, greater amounts of power are consumed in relation to higher audio frequencies.
Operational characteristics of the transducer driver circuit 126 also present opportunities to selectively smooth its power consumption, and thereby that of the implantable module 104. The P-MOSFET 450 and the N-MOSFET 452 exhibit parasitic capacitances (e.g., gate capacitances). Also, conductive paths in the ASIC exhibit parasitic capacitances. Each such capacitance is regarded as a type of power consumption generally referred to as a switching loss, PSW-loss. Switching losses can be characterized as follows.
PSW-loss=(CPD+CLayout)·VLL2·fSW [Watts] Equation 1
In Equation 1, CPD represents a power dissipation capacitance and is a virtual capacitance value given by the manufacturer of an ASIC. More particularly, CPD is a capacitance that consolidates most if not all parasitic capacitances of the switches SW1 and SW2. Also, CLayout represents an aggregate layout capacitance (including the capacitances of IC paths, PCB tracks, etc.). Note that CLayout excludes the capacitance of the stimulation transducer, CPz. For a Class-D amplifier, VLL is a supply voltage. Lastly, fSW represents the switching frequency.
In view of Equation 1, it can be seen that there is dependence of the switching losses upon the magnitude of the voltage VLL, namely PSW-loss=f(VLL2) in some embodiments of the present invention. If the voltage VLL can be selectively decreased, then significant reductions in the switching losses can be achieved for such embodiments because the switching losses are proportional to the square of the voltage VLL, namely PSW-loss=f(VLL2).
As noted above, in some exemplary embodiments, the level controller 168 is configured to recognize relatively quiet acoustical conditions of the recipient's environment and correspondingly adjust one or more operating parameters of the AMD 100 (e.g., bone conduction device 100C). The operating parameters that are adjusted are substantially time invariant parameters that are not used by the AMD to directly represent acoustic content of sound impinging upon the recipient. Such parameters include, for example, a voltage Vkk used internally by the RF modulator 114, a digital modulation parameter in the circumstance that the RF modulator 114 uses digital modulation, etc. Such adjustment results in power smoothing, as will be described below.
As noted above, the RF modulator block 114 can be configured to use the OOK (On-Off Keying) type of digital modulation. A more particular example of such operating parameters is the pulse width used by the OOK modulation scheme. In an exemplary OOK modulation scheme, a binary value of one is represented by the presence of a carrier wave, i.e., the presence of pulses, during an interval representing a value of a bit (hereinafter, “bit interval”). By contrast, a binary value of zero is represented by the absence of the carrier wave, i.e., the absence of pulses, during the bit time interval. So long as the width of the pulses is sufficient to permit their recognition as pulses, the value for the width of the pulses can be varied.
Another way of viewing the width of the pulses in the OOK carrier is as a duty cycle. For a given number of pulses, greater values for the width of the pulses achieve greater duty cycles. In contrast, smaller values for the width of the pulses achieve smaller duty cycles. It is to be recalled that the rectification circuit 140 extracts power from the RF link 130, and supplies the extracted power to the RF decoder and pulse generator 122 and the transducer driver circuit 126. By selectively reducing the pulse width of the OOK carrier, the amount of power extracted by the rectification circuit 140, and therefore the value of the resultant voltage VLL, can be selectively reduced, and so the power consumed by the transducer driver circuit 126 can be selectively reduced.
An example of a loudness:PW-mapping, according to an embodiment of the present invention, is illustrated in
Under relatively noisy conditions, the level controller 168 also may apply a default value of a gain kG that is applied to the audio signal from the audio transducer, where the default value kDEF is, e.g., zero gain or relatively little gain. Under the quiet conditions for which the level controller 168 selectively reduces the voltage VLL, it may be desirable also to correspondingly increase the gain kG applied to the audio signal from the audio transducer 108.
Accordingly, the level controller 168 can be configured with a second mapping, namely a loudness:kG mapping (e.g., in the form of another look-up table (LUT), another executable block of instructions, etc.) between loudness levels and values of the gain kG.
An example of a loudness:kG mapping, according to an embodiment of the present invention, is illustrated in
The RF modulator block 714B includes a digital RF modulator 751B that receives the audio signal (which can be either filtered or unfiltered), an RF driver voltage conditioner 755B that provides the pulse-width control signal PW_CTRL to the digital RF modulator 751B and an RF driver circuit 753B that operates upon a modulated output from the RF modulator 751B to generate the RF signal. The ALC signal is provided as a control signal to the RF driver voltage conditioner 755B, which then adjusts the pulse-width control signal PW_CTRL according to the ALC signal. The digital RF modulator 751B adjusts the width of the modulation pulses according to the pulse-width control signal PW_CTRL.
As noted above, the power-smoothing features detailed herein are usable in a variety of medical devices. In this regard, embodiments have been described in terms of an active transcutaneous bone conduction device 100C with reference to
The removable component 802 of
In operation, the voltage conditioner 886 generates a voltage VLL that is provided to the pulse generator 848 and the transducer driver circuit 826. Similarly, the stimulation transducer 828 can be regarded as a capacitive load to the transducer driver circuit 826.
As with pulse generator 148, the pulse generator 848 can be a pulse width modulator, pulse density modulator or a sigma-delta modulator. The pulse generator 848 produces two bit streams, P1 and P2, with each bit stream being 1-bit wide. It is to be observed that the bit streams P1 and P2 are non-overlapping. The transducer driver circuit 826, for example, can be driven directly with the two bit streams, P1 and P2. A simple OOK envelope detector can be made, e.g., using a diode loaded to an RC parallel circuit.
Similarly to the one or more operating parameters discussed above, operating parameters of the bone conduction device 800 include, for example, a level of the voltage VLL provided to the transducer driver circuit 826. Again, such parameters are parameters are substantially time invariant and not used by the AMD to directly represent acoustic content of sound impinging upon the recipient. Accordingly, like the level controller 168, not only is the level controller 868 operable to recognize relatively quiet acoustical conditions, but it is further operable to then adjust (by selectively reducing) a level of the voltage VLL provided to the transducer driver circuit 826.
More particularly, the level controller 868 is operable to determine a loudness value based upon the audio signal from the audio transducer 108. The level controller 868 is configured with a third mapping, namely a loudness:VLL mapping (e.g., in the form of a look-up table, an executable block of instructions, etc.) between loudness levels and levels of the voltage VLL. The level controller 868 is further operable to index the loudness level into the third mapping and retrieve therefrom a corresponding value of the voltage VLL.
An example of a loudness:VLL-mapping, according to an embodiment of the present invention, is illustrated in
As with level controller 168, the level controller 868 is similarly operable, under the quiet conditions for which the level controller 868 selectively reduces the voltage VLL, also to optionally and correspondingly increase the gain kG applied to the audio signal from the audio transducer 108.
Accordingly, the level controller 868 can be configured with the second mapping, similarly to the level controller 168.
Various aspects of the present invention provide advantages over the Background Art. For example, the arrangement shown allows much of the circuit complexity to remain in the external module 102 with a simplified arrangement of the implantable module 104.
The arrangements described herein may be used in a uni-directional system (i.e. power and data flow from the external module to the implantable module), thus allowing for further simplification of the implantable module. The various aspects of the present invention have been described with reference to specific embodiments. It will be appreciated however, that various variations and modifications may be made within the broadest scope of the principles described herein.
Some embodiments include methods of manufacturing and/or calibrating the AMD of
At block 904, an input signal having time-varying frequency components (e.g., an audio signal) is received. From block 904, the method proceeds to block 906, which entails the step of filtering the input signal.
More particularly, at block 906, the input signal is filtered according to the power consumption profile so as to selectively reduce one or more frequency components for which consumption of power by the functional component is relatively more dependent (i.e., one or more of the relatively more power intensive frequency components in the input signal). From block 906, the method proceeds to block 908, which entails the step of driving the functional component according to the filtered signal. From block 908, the method proceeds to block 910, which entails determining whether exit conditions have been satisfied (e.g., whether sufficient frequency component reduction has occurred to obtain desired power consumption reduction). If not, the method proceeds from block 910 back to block 906. If exit conditions have been satisfied, the method proceeds from block 910 to block 912, where the method ends.
It is further noted that this method may be practiced during normal use of the AMD. For example, the magnitude of the frequency reduction may be varied during normal use to further reduce power consumption. Such may be the case in the event of a batter with a very low charge, thus prolonging operation of the AMD for an additional period of time, however brief.
An exemplary embodiment includes a method executed by the AMD 100B of
In
It is noted that the just-described method may be practiced before or after implantation of the AMD. Its further noted that implantation includes attachment of an external component to the recipient that does not penetrate the skin.
Throughout the specification and the claims that follow, unless the context requires otherwise, the words “comprise” and “include” and variations such as “comprising” and “including” will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.
Reference herein to “one embodiment” or “an embodiment” means that a particular feature, structure, operation, or other characteristic described in connection with the embodiment may be included in at least one implementation of the present invention. However, the appearance of the phrase “in one embodiment” or “in an embodiment” in various places in the specification does not necessarily refer to the same embodiment. It is further envisioned that a skilled person could use any or all of the above embodiments in any compatible combination or permutation.
It is to be understood that the detailed description and specific examples, while indicating embodiments of the present invention, are given by way of illustration and not limitation. Many changes and modifications within the scope of the present invention may be made without departing from the spirit thereof, and the present invention includes all such modifications.
The present application is a Continuation application of U.S. patent application Ser. No. 14/886,683, filed Oct. 19, 2015, which is a Continuation application of U.S. patent application Ser. No. 13/301,946, filed Nov. 22, 2011, now U.S. Pat. No. 9,167,361, the entire contents of these applications being incorporated herein by reference in their entirety.
| Number | Name | Date | Kind |
|---|---|---|---|
| 8325964 | Weisman | Dec 2012 | B2 |
| 20040057586 | Licht | Mar 2004 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20200186948 A1 | Jun 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14886683 | Oct 2015 | US |
| Child | 16543813 | US | |
| Parent | 13301946 | Nov 2011 | US |
| Child | 14886683 | US |
