Electrical audio signal processing systems and devices – Hearing aids – electrical – Remote control – wireless – or alarm
Reexamination Certificate
1998-01-29
2001-05-29
Woo, Stella (Department: 2743)
Electrical audio signal processing systems and devices
Hearing aids, electrical
Remote control, wireless, or alarm
C381S312000
Reexamination Certificate
active
06240194
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a hearing aid comprising a controllable oscillator and a control circuit coupled thereto.
Such a hearing aid is disclosed in DE-C 4 221 304. Digital hearing aids require an oscillator to generate a clock signal. To obtain properly functioning hearing aids, the frequency of this clock signal must be determined in a stable and accurate manner. In general, such a stable and accurate clock signal can be obtained in a simple manner by using a crystal oscillator. However, crystal oscillators are not often used in hearing aids because of the dimensions of the crystals required by these oscillators. Instead, hearing aids are customarily provided with a controllable oscillator. In such hearing aids, the frequency of the clock signal generated by the controllable oscillator, which frequency is governed, inter alia, by voltage and temperature variations, can be regulated.
The hearing aid known from the above-mentioned German patent specification comprises a controllable oscillator and a control circuit which is coupled thereto. This control circuit comprises a memory in which a number of data words are stored. By manually selecting one specific data word from this memory, the frequency of the signal generated by the oscillator is set via a number of capacitors. However, in the known hearing aid, a fine adjustment of the oscillator frequency is not readily possible.
OBJECTS AND SUMMARY OF THE INVENTION
It is an object of the invention to provide a hearing aid of the type mentioned in the opening paragraph, in which the oscillator frequency remains substantially constant despite variations, inter alia, in the supply voltage and the temperature. To achieve this, the hearing aid in accordance with the invention is characterized in that the hearing aid further includes a receiver for receiving a reference signal from a remote control, the control circuit also being coupled to the receiver, and the control circuit being constructed so as to regulate a frequency of the oscillator by means of the reference signal received by the receiver.
By sending a reference signal generated in the remote control to the hearing aid, such a reference signal is available now in the hearing aid. By controlling the oscillator by means of the received reference signal, a substantially constant frequency of the oscillator is achieved despite variations in the supply voltage and the temperature.
The reference signal now can be generated by means of a crystal oscillator. In general, the use of a crystal in the remote control is not problematic because the space available in the remote control is generally sufficient.
An embodiment of the hearing aid in accordance with the invention is characterized in that the control circuit can be switched between at least a first and a second state, the control circuit being arranged so as to change, in the first state, the frequency in first frequency steps and, in the second state, in second frequency steps, the first frequency steps being larger than the second frequency steps. By virtue thereof, on the one hand, a frequency which differs relatively substantially from the desired frequency can be regulated relatively rapidly towards the desired value. In this case, the control circuit must be switched into the first state. On the other hand, if the frequency is already close to the desired frequency, the frequency can be accurately adjusted. In this case, the control circuit must be switched into the second state.
A further embodiment of the hearing aid in accordance with the invention is characterized in that the reference signal comprises a first sub-signal, with the control circuit being switched into the first state during reception of the first sub-signal, and, upon completion of the reception of the first sub-signal, the control circuit is switched into the second state.
The first sub-signal is selected so as to correspond to a first part of the reference signal. At the beginning of the reception of the reference signal (and hence at the beginning of the reception of the first sub-signal) it is not certain whether the frequency of the oscillator is close to the desired frequency. For this reason, during reception of the first sub-signal, the control circuit is always switched into the first state. By virtue thereof, the frequency, if it differs relatively substantially from the desired frequency, can be regulated relatively rapidly towards the desired value. Further, the length of the first sub-signal is selected so that, upon completion of the reception of the first sub-signal, the frequency is always close to the desired frequency. By virtue thereof, upon completion of the reception of the first sub-signal, it is sufficient to accurately regulate the frequency. At this stage, the control circuit is switched into the second state.
A further embodiment of the hearing aid in accordance with the invention is characterized in that the control circuit further comprises first and second memory means, the memory means being disposed so as to contain a control value corresponding to a frequency of the oscillator, and the reference signal further comprising a second sub-signal, the control circuit being arranged so as to determine, during reception of the second sub-signal, a first control value and store this value in the first memory means, and the control circuit further being embodied so as to read, upon completion of the reception of the second sub-signal, the first control value from the first memory means and store this value in the second memory means.
The length of the second sub-signal is selected so that the first control value, which is known upon completion of the reception of this second sub-signal, corresponds properly to the desired frequency of the oscillator. By storing this first control value in the second memory means, it becomes possible to fall back on this first control value when, during further reception of the reference signal, problems occur which cause the first control value to be no longer reliable.
A further elaboration of the last-mentioned embodiment of the hearing aid in accordance with the invention is characterized in that the reference signal also comprises a third sub-signal, with the control circuit being arranged so as to determine, during reception of the third sub-signal, a second control value and to store this value in the first memory means, and the control circuit further being embodied so as to read, upon completion of the reception of the third sub-signal, the first control value from the second memory means and to store this value in the first memory means.
The third sub-signal is selected so that the end of this signal corresponds to the end of the reference signal. If, after a complete reception of the reference signal, the first control value stored in the second memory means is always copied to the first memory means, a reliable control value is guaranteed which is available in the first memory means at the beginning of the reception of a subsequent reference signal.
These and other aspects of the invention will be apparent from and elucidated with reference to the embodiments described hereinafter.
REFERENCES:
patent: 4034300 (1977-07-01), Steckenbach
patent: 4959810 (1990-09-01), Darbee et al.
patent: 5012520 (1991-04-01), Steeger
patent: 5083312 (1992-01-01), Newton et al.
patent: 5563553 (1996-10-01), Jackson
patent: 5703541 (1997-12-01), Nakashima
patent: 5739725 (1998-04-01), Ferraiolo et al.
patent: 5835610 (1998-11-01), Ishige et al.
patent: 5896069 (1999-04-01), Williams et al.
patent: 4221304 (1993-09-01), None
“A Single Battery, 0.9V-Operated Digital Sound Processing IC Including AD/DA and IR Receiver with 2mW Power Consumption” by Harry Neuteboom et al; ISSCC97/Session 6/Low-Power and Mixed-Signal Processing/Paper TP6.4; IEEE International Solkid-Statie Circuits Conference.
Dabney P.
Franzblau Bernard
U.S. Philips Corporation
Woo Stella
LandOfFree
Hearing aid with external frequency control does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Hearing aid with external frequency control, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hearing aid with external frequency control will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2561227