Patent Application
20050085871
This application claims priority from Australian Provisional Patent Application No. 2003905730 filed on Oct. 20, 2003, the contents of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to covers and housings for electronic devices that use miniature batteries.
2. Related Art
Hearing aids and cochlear implants are useful in restoring the sensation of hearing to hearing impaired individuals.
A cochlear implant is used where the hair cells of the cochlea have been damaged to the extent that they are no longer able to convert the mechanical vibration of the cochlea fluid into an electrical signal.
The cochlear implant bypasses the hair cells of the cochlea and delivers electrical stimulation, representative of speech and environmental sounds, to the nerves in the cochlea. The neural impulses generated by this electrical stimulation are then communicated to the brain where they are interpreted as sound.
An example of a cochlear implant system is described in U.S. Pat. No. 4,532,930 (“Crosby”), the contents of which are incorporated herein by reference.
More recently, the physical dimensions of various external components have been able to be reduced. A relatively small unit capable of being worn behind the ear (“BTE”) can now house the microphone, batteries and sound processor circuitry.
However, the BTE configuration has increased the likelihood of the components coming into contact with moisture from ambient humidity, precipitation, perspiration, or shower or bath water, causing degradation and corrosion. Similarly, the components can become exposed to contaminants such as dust, hair care products and skin care products.
The above factors can increase the likelihood of intermittent power cut-outs.
It is desired to provide an alternative arrangement that ameliorates the foregoing drawbacks.
Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
In accordance with one aspect of the present invention, there is provided a housing for an electronic device powered by one or more batteries, said housing comprising:
In one embodiment, the at least one aperture can be provided in the movable portion. In this or another embodiment, the hydrophobic mesh member can be a hydrophobic, airflow membrane, such as a membrane formed from ePTFE.
In a further embodiment, the at least one aperture can include two circular portions.
in yet another embodiment, the at least one aperture can further include a screen member that overlays the hydrophobic mesh member. The screen member can be formed from a non-corrosive metal.
In a still further embodiment, the housing can include two apertures.
In a further embodiment, the electronic device can be an external component of a cochlear implant system.
A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein:
Before describing the features of the present invention in detail, it is convenient to describe the construction and overall operation of one example of a BTE cochlear implant system.
Referring to
In operation, the sound processor device 29 receives sound and calculates a digital data stream, based on a selected coding strategy. The digital data stream thus represents stimulation parameters for application to the electrode array.
The digital data stream is then modulated on to a high frequency (RF) carrier signal, and transmitted together with a power signal, to the implanted receiver-stimulator unit 22 over a transcutaneous radio frequency (RF) link.
The electrical signals received by the receiver antenna coil 23 are provided to the receiver-stimulator unit 22 are applied to the electrode array 20. The electrode array 20 applies electrical stimulation to the basilar membrane 8 and hence the auditory nerve 9 to create a sensation of hearing in the recipient. The electrical stimulation signals are normally bi-phasic and charge balanced to ensure there is no net DC current flow.
It is noted that the receiver coil 23 can also transmit signals back to the transmitter/headset coil 24 for telemetry purposes.
Referring now to
Referring now to
In this particular example, the shaped opening 31 includes two circular portions. Each of the circular portions of the shaped opening have a similarly configured ePTFE hydrophobic, airflow membrane 33. An example of a material by which the membrane 33 can be made is Gore-Tex™.
The shaped opening 31 further includes a metallic mesh 32 fitted over each of the membranes 33 as shown, for example, in the exploded perspective view of
Preferably, the metallic mesh 32 is made from a non-corrosive, biocompatible material and is removable from the battery cover 30, to allow for replacement and service of the membrane 33, the mesh 32 and/or the holding rings and fixing elements 34.
In this example, each membrane 33 is positioned at about halfway between the underside planar surface of the mesh 32 and the upper, or outer surface of the batteries installed in the battery housing 35.
The present inventors have carried out a number of tests on the modified battery cover 30 and have demonstrated that this can provide an advantageous alternative to the prior art arrangements.
Specifically, the test results show that the modified battery cover 30 can improve the current delivery capacity of the batteries 36, thus making more current available for the increasing demands associated with more sophisticated speech processing strategies. As indicated in Table 1, the current capacity of the batteries 36 with the modified battery cover 30 is at least 20% greater at the beginning of the battery life. It is estimated that the current carrying capacity of the batteries 36 is at least 5% greater at the end of battery life.
Further, the modified battery cover 30 can reduce the incidence of intermittent faults, thought to have been due to the battery characteristics. The batteries 36 still provide an acceptable mAh capacity and are far less likely to prematurely reach the “low battery cutoff“ voltage.
Moreover, the modified battery cover 30 is advantageous when used in high humidity environments or during sporting activities. Any moisture or fluid that happens to creep into the housing of the speech processor device is quickly evaporated, due to an increased airflow that is provided to the interior of the sound processor device.
Referring now to
The battery drawer 51 provides a hydrophobic membrane 52, not unlike that described in relation to the first arrangement, fitted into a membrane mounting assembly 53. The membrane mounting assembly 53 comprises a pair of rings 56 that are adapted to be pressed over the hydrophobic membrane 52, so as to keep the hydrophobic membrane 52 stretched and fixed into position.
The battery drawer 51 is adapted to slide into the main body portion 54 of the BTE unit 50 where it is locked into position. A metallic perforated mesh 55 having a considerable opening area is fitted near the underside of the battery drawer 51, as shown in
Test Results
Tests on the present invention were conducted in two phases: Phase 1, where a constant voltage load was applied to the miniature batteries, and Phase 2, where production standard BTE devices were used.
The Phase 1 tests involved connecting the batteries to a 2.2 Volt (V), constant voltage load and measuring the available instantaneous current capacity of the various batteries. This measurement was carried out for a room environment situation, and then repeated for an elevated temperature and humidity.
The Phase 2 set of tests involved connecting the batteries to a working speech processor load, to simulate real-life conditions. The Phase 2 tests also involved testing under periods of no noise, alternating with random noise bursts at regular intervals to cause excess current drain from the batteries.
Referring now to
The elevated temperature and humidity conditions were achieved using an oven set at 30° C., and in which a 500 ml beaker holding approximately 250 ml of water was placed inside. After around 20 mins, sufficient humidity was developed in the oven and the tests could be conducted.
The test schedule was as follows:
RH = Relative Humidity
In all cases, the tabs of the batteries were removed and allowed to activate in air for around 5 minutes before being tested.
Phase 1, Part A: Tests at Room Environment
This test was conducted for different makes of batteries. The two series-connected battery cells were placed in a dummy battery holder without any cover and placed on the inside wall of the test container 60, using a non permanent, adhesive putty. The dummy battery holder without a cover provides a baseline because this represents a maximum current output that may be obtained from a battery during test.
A constant voltage load circuit was then applied, so as to maintain a load of between 2.200 and 2.199 volts DC. The discharge current from the batteries was then logged for 10 minutes.
A prior art battery cover was then placed over the dummy battery holder and the 10 minute discharge test was repeated. Similarly, the modified battery cover was fitted to the dummy battery holder and the 10 minute discharge test again repeated.
Finally, the batteries were allowed to discharge without any cover, until the discharge current fell to 14 mA, thus providing an ‘end of life’ series of readings.
Phase 1, Part B: Tests in Elevated Temperature and Humidity Conditions
As earlier discussed, this test was set up by placing a 500 ml beaker filled with approx. 250 ml water in an oven set to 30° C. for about 20 minutes. A humidity meter was used to verify the required humidity parameters as set out in the test schedule.
The batteries were placed in the dummy battery holder and a prior art cover fitted. The 2.2V constant voltage load was connected and the holder suspended just above the beaker while current readings were recorded until the end of the battery life.
This test was carried out for at least two different makes of batteries with both the prior art cover and the modified cover.
Phase 2: Tests with Working Speech Processors
This test was conducted only with Toshiba 675 SP batteries, as the differences between the battery cover designs with different makes of batteries was already tested in Phase 1.
The test was performed for each of three BTE speech processors having a MAP selected to elicit maximum speech processor power consumption (e.g. high pulse width, high T & C levels, high number of maxima etc). The sensitivity control was kept at maximum during all tests.
Firstly, the batteries were placed in a dummy battery holder with a prior art battery cover. The holder was placed on the inside wall of the container using adhesive putty and the airflow set as per phase 1. The output terminals of the dummy battery holder were connected to the battery terminals of the BTE device under test, with an ammeter in series and a voltmeter in parallel.
An RF coil connected to the BTE device was then coupled to a receiver circuit in an ‘implant in a box’ system. An ‘implant in a box system’ is one constructed for the specific purpose of simulating the working of a BTE device under test.
To stimulate the sudden bursts of sound in real life, a signal generator was used to supply a sine wave burst of 4 KHz to a pair of speakers placed approximately 25 cm from the speech processor. The amplitude of the sine wave bursts was set so that at the sound burst, the current supplied by the batteries was 18 mA (±2 mA).
The current consumption and battery voltage during the sound burst tests was logged at 2 second intervals. In particular, the readings were monitored for any sudden change in the current/voltage, as more intermittency may be expected at the end of the battery life. Intermittency was identified by a sudden fall of current, to a value less than 1 mA.
Next the prior art battery cover was replaced with the modified battery cover and the test repeated.
The covers were swapped at least 3 times at 30 minutes time intervals and the changes in the supply voltage/current of the battery were monitored. These steps were repeated at the end of battery life period.
Referring now to
It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.
| Number | Date | Country | Kind |
|---|---|---|---|
| 200395730 | Oct 2003 | AU | national |
