CA2099187A1 - Hearing aid - Google Patents
Hearing aidInfo
- Publication number
- CA2099187A1 CA2099187A1 CA002099187A CA2099187A CA2099187A1 CA 2099187 A1 CA2099187 A1 CA 2099187A1 CA 002099187 A CA002099187 A CA 002099187A CA 2099187 A CA2099187 A CA 2099187A CA 2099187 A1 CA2099187 A1 CA 2099187A1
- Authority
- CA
- Canada
- Prior art keywords
- voltage
- integrator
- hearing aid
- output
- input
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
- H04R25/50—Customised settings for obtaining desired overall acoustical characteristics
- H04R25/505—Customised settings for obtaining desired overall acoustical characteristics using digital signal processing
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R25/00—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception
- H04R25/50—Customised settings for obtaining desired overall acoustical characteristics
- H04R25/502—Customised settings for obtaining desired overall acoustical characteristics using analog signal processing
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
- H04R2225/00—Details of deaf aids covered by H04R25/00, not provided for in any of its subgroups
- H04R2225/33—Aspects relating to adaptation of the battery voltage, e.g. its regulation, increase or decrease
Landscapes
- Health & Medical Sciences (AREA)
- General Health & Medical Sciences (AREA)
- Neurosurgery (AREA)
- Otolaryngology (AREA)
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Acoustics & Sound (AREA)
- Signal Processing (AREA)
- Amplifiers (AREA)
- Adornments (AREA)
- Finger-Pressure Massage (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A hearing aid has a microphone, an amplifier, an earphone, and a battery as a source for an operating voltage. A switching amplifier is provided as an output stage.
A delta voltage generator forms a base signal generator for a pulse-duration-modulated signal with which the switching amplifier can be controlled. The delta voltage generator comprises at least one integrator whose integration direction is reversible, dependent on an input signal thereto. A quotient of an operating voltage and a peak value of a delta voltage of the delta voltage generator remains at least largely constant given a changing operating voltage. For that purpose, the integrator is in an interactive connection with a switch at its input side and with a comparison circuit at its output side. The comparison circuit controls the switch by which the input signal can be supplied to the integrator, dependent on at least one threshold voltage derived from the operating voltage.
A hearing aid has a microphone, an amplifier, an earphone, and a battery as a source for an operating voltage. A switching amplifier is provided as an output stage.
A delta voltage generator forms a base signal generator for a pulse-duration-modulated signal with which the switching amplifier can be controlled. The delta voltage generator comprises at least one integrator whose integration direction is reversible, dependent on an input signal thereto. A quotient of an operating voltage and a peak value of a delta voltage of the delta voltage generator remains at least largely constant given a changing operating voltage. For that purpose, the integrator is in an interactive connection with a switch at its input side and with a comparison circuit at its output side. The comparison circuit controls the switch by which the input signal can be supplied to the integrator, dependent on at least one threshold voltage derived from the operating voltage.
Description
209~1~7 S P E C I F I C A T l O N
TITLE
"HEARING AID"
BACKGROUND OF THE INVENTION
The present invention is directed to a hearing aid comprising an input transducer (microphone), an amplifier means, an output transducer (earphone) and a power source (battery) as a source for an operating voltage. A switching amplifier is provided as an output stage and a delta voltage generator as a base signal generator for a pulse-duration-modulated signal with which the switching amplifier can be controlled.
The delta voltage generator comprises at least one integrator whose integration direction can be reversed, dependent on an input signal.
DE-C 36 16 752 discloses a hearing aid of the type initially cited. In this known hearing aid, the delta voltage generator is composed of a square-wave generator which is followed by an integrator for generating a delta voltage. The integrator is formed of a simple RC circuit and is biased by a voltage divider. The voltage divider is composed of two resistors that form a series circuit between the two poles of the operating voltage.
A hearing aid battery serves as a source for the operating voltage of the various circuit components ot the hearing aid in hearing aids of the type initially cited. As is known, the hearing aid battery outputs a changing, dropping operating voltage during its useful life. The useful signal amplification is thereby particulariy reduced, this being obviously undesirable. The gain of the useful signal derives as a quotient from the mean value of the output voltage of the useful signal at the output stage and of the input voltage of the useful signal. In hearing alds having switching amplifier output stages, the useful signal is contained in the modulation of the pulse-duration-modulated signal. A delta voltage generator is required for generating the pulse-duration modulation. This delta r 209918~
voltage generator supplies a delta voltage signal that is compared to the useful signal in a modulator. The pulse-duration-modulated signal is available at the output of the modulator which, for example, can be designed as a comparator. The delta voltage, particularly the peak value thereof, is also dependent on the operating voltage.
It has been recognized with the invention that the gain of the useful si~nal also derives as a quotient of the operating voltage and of the peak value of the delta voltage that is generated by the delta voltage generator.
SUMMARY OF THE INVENTION
An object of the invention is to design a hearing aid of the type initially cited such that the quotient of the operating voltage and the peak value of the delta voltage remains at least largely constant given a changing operating voltage.
In the hearing aid according to the present invention, an input transducer such as a microphone, an amplifier means, an output transducer such as an earphone, and a current source such as a battery as a source for an operating voltage are provided. The earphone is connected to a switching amplifier as an output stage. A delta voltage generator as a base signal generator for a pulse-duration-modulated signai is provided by which the switching amplifier can be controlled. The delta voltage generator has at least one integrator whose integration direction is reversible dependent on an input signal thereto. The integrator is in an interactive connection with a switch means at its input side and with a comparison circuit at its output side. The comparison circuit controls the switch means so that the input signal supplied to the integrator is dependent on at least one threshold voltage derived from the operating voltage.
In the hearing aid of the invention, the delta voltage generator comprises a comparison circuit with whose output signal an input signal becomes suppliable, for example formable (generateable) as well, to the input side of the integrator onthe basis of a switch means. According to the invention, the delta voltage generator acts like a self-excited oscillator. The peak value of the generated delta voltage is prescribed by at least 20991~7 one threshold voltage that, for example, is derived from the operating voltage with a voltage divider. The output voltage of the integrator is compared to this threshold voltage in the comparison circuit. When the output voltage of the integrator reaches the threshold voltage, the comparison circuit outputs an output signal to the switch means. The input signal is supplied to the integrator by the switch means.
According to the invention, the peak value of the delta voltage linearly followsthe changes of the operating voltage. The quotient of operating voltage and peak value of the delta voltage thereby remains constant, given a varying operating voltage.
Consequently, the gain of the useful signal also remains constant because the peak value of the delta voltage linearly changes with the operating voltage.
A further critical advantage of the invention is comprised in the designing of the delta voltage generator as a self-excited oscillator. A separate oscillator, for example a square-wave generator, which in turn would again be dependent on operating voltage fluctuations, is thereby eliminated. Changes in gain that arise due to the drive of an integrator with a square-wave signal from a square-wave generator are consequently also avoided by the invention.
In a development of the invention, the switch means can comprise a bistable trigger circuit. The output signal of this trigger circuit in one version of the invention can also be employed as an input signal for the integrator. At every switch-over of the trigger circuit, the input signal at the integrator changes according to the output signal of the trigger circuit from a high level to a low level, or from a low level to a high level. An automatic change of the integration direction in the integrator is thereby achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a hearing aid comprising a delta voltage generator; and Figure 2 is a hearing aid with a more detailed illustration of the switching amplifier and comprising a modified delta voltage generator.
20991~7 DESCRIPTION OF THE PREFERRED EMBODIMENTS
In Figure 1, a dot-dash line symbolically illustrates a hearing aid 1. The hearing aid 1 comprises a microphone 2 as an input transducer for picking up useful signals in the range of human hearing. Thc useful signals are pre-amplified in an amplifier 3, which can also be designed in multi-stage fashion, and are forwarded to a modulator 4. The modulator 4 receives a delta voltage from a delta voltage generator 5 via a line 6, this delta voltage serving as a higher-frequency base signal for the useful signal. A pulse-duration-modulated signal that is supplied via a line 7 to an output stage designed as a switching amplifier 8 is available at the output of the modulator 4. The switching amplifier 8 has its output side connected to an electrical earphone 9 as an output transducer for reproducing the amplified useful signal.
The delta voltage generator 5 comprises an integrator 10. The integrator 10 is in an interactive connection with a switch means 12 at its input 11 and wlth a comparison circuit 14 at its output 13. The comparison circuit 14, furthermore, receives at least one threshold voltage that is derived via a voltage divider 15 from a battery 16 as a power source outputting an operating voltage UB.
In a development of the invention, two threshold voltages that can be taken from the voltage divider 15 are supplied to the comparison circuit 14 via lines 17 and 18 in this exemplary embodiment. The voltage divider 15 is connected electrically parallel to the battery 16, and comprises a series circuit composed of the resistors R1 through R4.
The two threshold voltages via the lines 17 and 18 can be taken at Junctions 19 and 20 between the resistors R1 and R2, or R3 and R4.
The comparison circuit 14 is designed as a comparator circuit comprising the comparators 21 and 22, preferably as a window comparator circuit. For that purpose, a high threshold voltage frorn the voltage divider 15 is forwarded to the non-inverting input of the comparator 21, and a low threshold voltage from the voltage divider 15 is forwarded to the inverting input of the comparator 22. The inverting input of the comparator 21 and 20991~7 the non-inverting input of the comparator 22 are connected in common to the output 13 of the integrator 10.
In an advantageous development of the invention, the switch means 12 comprises a bistable trigger circuit 23 that is preferably designed as a R/S flip-flop. A first input 24 of the bistable trigger circuit 23 is connected to the output of the comparator 21.
A second input 25 of the bistable trigger circuit 23 is connected to the output of the comparator 22.
In a development of the invention, the switch means 12 comprises a voltage switch-over 26 that can also be digitally driven by the trigger circuit 23. The voltage switch-over comprises input terminals 27 and 28. Two different DC voltages can be applied to these input terminals 27 and 28, these DC voltages being alternately connectable to the input 11 at the integrator 10 via the switch means 12 or via the voltage switch-over 26 depending on the comparison circuit 14, for example via an output terminal 29.
In the exemplary embodiment of Figure 1, the input terminal 27 of the voltage swltch-over 26 is connected to the positive pole and the input terminal 28 of the voltage switch-over 26 is connected to the negative pole (ground) of the operating voltage U~ that can be taken from the hearing aid battery 16. As a result thereof, a current I flowing into the integrator 10 at the input 11 as an input signal is linearly dependent on the operating voltage U~. As a result of this inventively effected dependency of the integration current I on the operating voltage U~, one advantageously obtains a frequency constancy of the delta signal on the line 6 given a varying operating voltage U~. Consequently, the delta voltage generator in the hearing aid of the invention works with constant frequency, even given fluctuations in operating voltage.
A reversal of the integration direction at the output side of the integrator 10 is effected by the switching of the input signal, for example of the integration current 1, at the input 11 of the integrator 10 by the switch means 12. The potential (for example, plus or minus potential of the battery 16) respectively switched on by the switch means 12 is 20991~7 maintained by the storage effect of the trigger circuit 23 until the integrated output signal at the output 13 of the integrator 10 coincides with a threshold voltage on the line 17 or 18. In case of such a coincidence, one of the two comparators 21 or 22 supplies an output signal with which the bistable trigger circuit 23 is flipped into the respectively complementary status. As a result thereof, the polarity at the input 11 of the intesrator 10 is again switched via ths voltage switch-over 26, as a result whereof another reversal of the integration direction in the integrator 10 arises. In this embodiment, consequently the delta voltage generator works automatically and without a separate generator, for example a square-wave generator.
In a development of the invention, the integrator 10 comprises an operational amplifier 30 whose output 31 is capacitatively connected to the inverting input 32 thereof.
The non-inverting input 33 is connected to approximately half the operating voltage U~, via the voltage divider 15. A resistor 34 is arranged between the input 11 of the integrator and the input 32 of the operational amplifier 30; this resistor 34 defines the output frequency of the delta generator together with a capacitor 35.
The hearing aid shown in Figure 2 comprising the delta voltage generator 5 and comprising the switching amplifier 8 is modified in terms of its hearing aid components in comparison to the hearing aid shown in Figure 1. The reference characters that agree in Figure 2 and in Figure 1 refer to equivalent hearing aid components.
By adding a resistor R2, the voltage divider 15 in the delta vottage generator 5of Figure 2 comprises a series circuit of a total of four resistors R1 through R4. When the sums of the resistance vaiues R1 and R2 as well as R3 and R4 are respectively selected of the same size, half the operating voltage UB can be taken at their middle junction 36.
The non-inverting input 33 of the operational amplifier 30 in the integrator 10 is supplied with this half operating voltage in this exemplary embodiment. When, furthermore, the resistors R1 or R4 have respectively twice the value of resistance in comparison to the resistors R2 or R3, the peak value of the delta voltage output by the integrator 10 via the line 6 to the modulator 4 amounts to one-third of the operating voltage U~. The zero 20~9187 potential of this delta voltage lies at half the operating voltage UB also because of the symmetry of the comparison circuit 14 designed as a window comparator. Since an input voltage that is symmetrical to half the operating voltage U~ is supplied to the integrator 10 via the voltage switch-over 26, the integration currents, and thus the two slopes of the delta signal, are also the same, except for the operational sign. As a result thereof, the arising square-wave signal at the output of the bistable trigger circuit 23 has a pulse-duty factor of exactly 50%. According to Figure 2, the output signal of the bistable trigger circuit 23 controls the voltage switch-over 26 via a driver 37.
Given the dimensionings of the voltage divider 15 recited here by way of example, the frequency of ths delta signal can be derived and calculated from the following relationships:
U~/2 . TDr/2 = U~/3;
R C
TDr = 4 R C;
fDr 4 R C
Denoted in the equations are:
R C = time constant of the integrator U~/2 = input voltage of the integrator U~/3 = voltage change during half a period of the delta signal TDr = period of the delta signal.
The switching amplifier 8 in Figure 2 is designed as a push-pull circuit and is therefore additionally driven via an inverter 38 for generating an additional, complementary drive signal. The switching amplifier 8 according to Figure 2 comprises four MOSFET
transistors T1 through T4 that operate in switched mode. The transistors T1 and T2 as well as the transistors T3 and T4 are each respectively designed complementarily relative to one another. The switching amplifier 8 is supplied with operating voltage via terminals 39 and 40. Due to the switched mode, either the transistors T1 and T4 or T3 and T2 are ~99187 simultaneously transmissive. The time span within which these transistors are transmissive is defined by the respective pulse duration of the individual pulses of the pulse-duration-modulated signal that is supplied to the switching amplifier via inputs 41 and 42. Given a change of the level in the pulse-duration-modulated signal, the transmissive transistors conseguently also switch into the non-transmissive condition and the transistors that were previously not transmissive thus become transmissive. As a result, the earphone 9 arranged in the bridge arm of the switching amplifier 8 is consequently switched between the operating voltage UB (plus and minus pole) Iying at the terminals 39 and 40. As a result of the low-pass effect of the earphone 9, the useful signal is filtered out from the pulse-duration-modulated signal and is made audible.
Although various minor changes and modifications might be suggested by those skilled in the art, it will be understood that I wish to include within the scope of the patent warranted hereon all such changes and modifications as reasonably come within my contribution to the art.
TITLE
"HEARING AID"
BACKGROUND OF THE INVENTION
The present invention is directed to a hearing aid comprising an input transducer (microphone), an amplifier means, an output transducer (earphone) and a power source (battery) as a source for an operating voltage. A switching amplifier is provided as an output stage and a delta voltage generator as a base signal generator for a pulse-duration-modulated signal with which the switching amplifier can be controlled.
The delta voltage generator comprises at least one integrator whose integration direction can be reversed, dependent on an input signal.
DE-C 36 16 752 discloses a hearing aid of the type initially cited. In this known hearing aid, the delta voltage generator is composed of a square-wave generator which is followed by an integrator for generating a delta voltage. The integrator is formed of a simple RC circuit and is biased by a voltage divider. The voltage divider is composed of two resistors that form a series circuit between the two poles of the operating voltage.
A hearing aid battery serves as a source for the operating voltage of the various circuit components ot the hearing aid in hearing aids of the type initially cited. As is known, the hearing aid battery outputs a changing, dropping operating voltage during its useful life. The useful signal amplification is thereby particulariy reduced, this being obviously undesirable. The gain of the useful signal derives as a quotient from the mean value of the output voltage of the useful signal at the output stage and of the input voltage of the useful signal. In hearing alds having switching amplifier output stages, the useful signal is contained in the modulation of the pulse-duration-modulated signal. A delta voltage generator is required for generating the pulse-duration modulation. This delta r 209918~
voltage generator supplies a delta voltage signal that is compared to the useful signal in a modulator. The pulse-duration-modulated signal is available at the output of the modulator which, for example, can be designed as a comparator. The delta voltage, particularly the peak value thereof, is also dependent on the operating voltage.
It has been recognized with the invention that the gain of the useful si~nal also derives as a quotient of the operating voltage and of the peak value of the delta voltage that is generated by the delta voltage generator.
SUMMARY OF THE INVENTION
An object of the invention is to design a hearing aid of the type initially cited such that the quotient of the operating voltage and the peak value of the delta voltage remains at least largely constant given a changing operating voltage.
In the hearing aid according to the present invention, an input transducer such as a microphone, an amplifier means, an output transducer such as an earphone, and a current source such as a battery as a source for an operating voltage are provided. The earphone is connected to a switching amplifier as an output stage. A delta voltage generator as a base signal generator for a pulse-duration-modulated signai is provided by which the switching amplifier can be controlled. The delta voltage generator has at least one integrator whose integration direction is reversible dependent on an input signal thereto. The integrator is in an interactive connection with a switch means at its input side and with a comparison circuit at its output side. The comparison circuit controls the switch means so that the input signal supplied to the integrator is dependent on at least one threshold voltage derived from the operating voltage.
In the hearing aid of the invention, the delta voltage generator comprises a comparison circuit with whose output signal an input signal becomes suppliable, for example formable (generateable) as well, to the input side of the integrator onthe basis of a switch means. According to the invention, the delta voltage generator acts like a self-excited oscillator. The peak value of the generated delta voltage is prescribed by at least 20991~7 one threshold voltage that, for example, is derived from the operating voltage with a voltage divider. The output voltage of the integrator is compared to this threshold voltage in the comparison circuit. When the output voltage of the integrator reaches the threshold voltage, the comparison circuit outputs an output signal to the switch means. The input signal is supplied to the integrator by the switch means.
According to the invention, the peak value of the delta voltage linearly followsthe changes of the operating voltage. The quotient of operating voltage and peak value of the delta voltage thereby remains constant, given a varying operating voltage.
Consequently, the gain of the useful signal also remains constant because the peak value of the delta voltage linearly changes with the operating voltage.
A further critical advantage of the invention is comprised in the designing of the delta voltage generator as a self-excited oscillator. A separate oscillator, for example a square-wave generator, which in turn would again be dependent on operating voltage fluctuations, is thereby eliminated. Changes in gain that arise due to the drive of an integrator with a square-wave signal from a square-wave generator are consequently also avoided by the invention.
In a development of the invention, the switch means can comprise a bistable trigger circuit. The output signal of this trigger circuit in one version of the invention can also be employed as an input signal for the integrator. At every switch-over of the trigger circuit, the input signal at the integrator changes according to the output signal of the trigger circuit from a high level to a low level, or from a low level to a high level. An automatic change of the integration direction in the integrator is thereby achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a hearing aid comprising a delta voltage generator; and Figure 2 is a hearing aid with a more detailed illustration of the switching amplifier and comprising a modified delta voltage generator.
20991~7 DESCRIPTION OF THE PREFERRED EMBODIMENTS
In Figure 1, a dot-dash line symbolically illustrates a hearing aid 1. The hearing aid 1 comprises a microphone 2 as an input transducer for picking up useful signals in the range of human hearing. Thc useful signals are pre-amplified in an amplifier 3, which can also be designed in multi-stage fashion, and are forwarded to a modulator 4. The modulator 4 receives a delta voltage from a delta voltage generator 5 via a line 6, this delta voltage serving as a higher-frequency base signal for the useful signal. A pulse-duration-modulated signal that is supplied via a line 7 to an output stage designed as a switching amplifier 8 is available at the output of the modulator 4. The switching amplifier 8 has its output side connected to an electrical earphone 9 as an output transducer for reproducing the amplified useful signal.
The delta voltage generator 5 comprises an integrator 10. The integrator 10 is in an interactive connection with a switch means 12 at its input 11 and wlth a comparison circuit 14 at its output 13. The comparison circuit 14, furthermore, receives at least one threshold voltage that is derived via a voltage divider 15 from a battery 16 as a power source outputting an operating voltage UB.
In a development of the invention, two threshold voltages that can be taken from the voltage divider 15 are supplied to the comparison circuit 14 via lines 17 and 18 in this exemplary embodiment. The voltage divider 15 is connected electrically parallel to the battery 16, and comprises a series circuit composed of the resistors R1 through R4.
The two threshold voltages via the lines 17 and 18 can be taken at Junctions 19 and 20 between the resistors R1 and R2, or R3 and R4.
The comparison circuit 14 is designed as a comparator circuit comprising the comparators 21 and 22, preferably as a window comparator circuit. For that purpose, a high threshold voltage frorn the voltage divider 15 is forwarded to the non-inverting input of the comparator 21, and a low threshold voltage from the voltage divider 15 is forwarded to the inverting input of the comparator 22. The inverting input of the comparator 21 and 20991~7 the non-inverting input of the comparator 22 are connected in common to the output 13 of the integrator 10.
In an advantageous development of the invention, the switch means 12 comprises a bistable trigger circuit 23 that is preferably designed as a R/S flip-flop. A first input 24 of the bistable trigger circuit 23 is connected to the output of the comparator 21.
A second input 25 of the bistable trigger circuit 23 is connected to the output of the comparator 22.
In a development of the invention, the switch means 12 comprises a voltage switch-over 26 that can also be digitally driven by the trigger circuit 23. The voltage switch-over comprises input terminals 27 and 28. Two different DC voltages can be applied to these input terminals 27 and 28, these DC voltages being alternately connectable to the input 11 at the integrator 10 via the switch means 12 or via the voltage switch-over 26 depending on the comparison circuit 14, for example via an output terminal 29.
In the exemplary embodiment of Figure 1, the input terminal 27 of the voltage swltch-over 26 is connected to the positive pole and the input terminal 28 of the voltage switch-over 26 is connected to the negative pole (ground) of the operating voltage U~ that can be taken from the hearing aid battery 16. As a result thereof, a current I flowing into the integrator 10 at the input 11 as an input signal is linearly dependent on the operating voltage U~. As a result of this inventively effected dependency of the integration current I on the operating voltage U~, one advantageously obtains a frequency constancy of the delta signal on the line 6 given a varying operating voltage U~. Consequently, the delta voltage generator in the hearing aid of the invention works with constant frequency, even given fluctuations in operating voltage.
A reversal of the integration direction at the output side of the integrator 10 is effected by the switching of the input signal, for example of the integration current 1, at the input 11 of the integrator 10 by the switch means 12. The potential (for example, plus or minus potential of the battery 16) respectively switched on by the switch means 12 is 20991~7 maintained by the storage effect of the trigger circuit 23 until the integrated output signal at the output 13 of the integrator 10 coincides with a threshold voltage on the line 17 or 18. In case of such a coincidence, one of the two comparators 21 or 22 supplies an output signal with which the bistable trigger circuit 23 is flipped into the respectively complementary status. As a result thereof, the polarity at the input 11 of the intesrator 10 is again switched via ths voltage switch-over 26, as a result whereof another reversal of the integration direction in the integrator 10 arises. In this embodiment, consequently the delta voltage generator works automatically and without a separate generator, for example a square-wave generator.
In a development of the invention, the integrator 10 comprises an operational amplifier 30 whose output 31 is capacitatively connected to the inverting input 32 thereof.
The non-inverting input 33 is connected to approximately half the operating voltage U~, via the voltage divider 15. A resistor 34 is arranged between the input 11 of the integrator and the input 32 of the operational amplifier 30; this resistor 34 defines the output frequency of the delta generator together with a capacitor 35.
The hearing aid shown in Figure 2 comprising the delta voltage generator 5 and comprising the switching amplifier 8 is modified in terms of its hearing aid components in comparison to the hearing aid shown in Figure 1. The reference characters that agree in Figure 2 and in Figure 1 refer to equivalent hearing aid components.
By adding a resistor R2, the voltage divider 15 in the delta vottage generator 5of Figure 2 comprises a series circuit of a total of four resistors R1 through R4. When the sums of the resistance vaiues R1 and R2 as well as R3 and R4 are respectively selected of the same size, half the operating voltage UB can be taken at their middle junction 36.
The non-inverting input 33 of the operational amplifier 30 in the integrator 10 is supplied with this half operating voltage in this exemplary embodiment. When, furthermore, the resistors R1 or R4 have respectively twice the value of resistance in comparison to the resistors R2 or R3, the peak value of the delta voltage output by the integrator 10 via the line 6 to the modulator 4 amounts to one-third of the operating voltage U~. The zero 20~9187 potential of this delta voltage lies at half the operating voltage UB also because of the symmetry of the comparison circuit 14 designed as a window comparator. Since an input voltage that is symmetrical to half the operating voltage U~ is supplied to the integrator 10 via the voltage switch-over 26, the integration currents, and thus the two slopes of the delta signal, are also the same, except for the operational sign. As a result thereof, the arising square-wave signal at the output of the bistable trigger circuit 23 has a pulse-duty factor of exactly 50%. According to Figure 2, the output signal of the bistable trigger circuit 23 controls the voltage switch-over 26 via a driver 37.
Given the dimensionings of the voltage divider 15 recited here by way of example, the frequency of ths delta signal can be derived and calculated from the following relationships:
U~/2 . TDr/2 = U~/3;
R C
TDr = 4 R C;
fDr 4 R C
Denoted in the equations are:
R C = time constant of the integrator U~/2 = input voltage of the integrator U~/3 = voltage change during half a period of the delta signal TDr = period of the delta signal.
The switching amplifier 8 in Figure 2 is designed as a push-pull circuit and is therefore additionally driven via an inverter 38 for generating an additional, complementary drive signal. The switching amplifier 8 according to Figure 2 comprises four MOSFET
transistors T1 through T4 that operate in switched mode. The transistors T1 and T2 as well as the transistors T3 and T4 are each respectively designed complementarily relative to one another. The switching amplifier 8 is supplied with operating voltage via terminals 39 and 40. Due to the switched mode, either the transistors T1 and T4 or T3 and T2 are ~99187 simultaneously transmissive. The time span within which these transistors are transmissive is defined by the respective pulse duration of the individual pulses of the pulse-duration-modulated signal that is supplied to the switching amplifier via inputs 41 and 42. Given a change of the level in the pulse-duration-modulated signal, the transmissive transistors conseguently also switch into the non-transmissive condition and the transistors that were previously not transmissive thus become transmissive. As a result, the earphone 9 arranged in the bridge arm of the switching amplifier 8 is consequently switched between the operating voltage UB (plus and minus pole) Iying at the terminals 39 and 40. As a result of the low-pass effect of the earphone 9, the useful signal is filtered out from the pulse-duration-modulated signal and is made audible.
Although various minor changes and modifications might be suggested by those skilled in the art, it will be understood that I wish to include within the scope of the patent warranted hereon all such changes and modifications as reasonably come within my contribution to the art.
Claims (13)
1. A hearing aid, comprising:
an input transducer connected to an amplifier, an output of the amplifier connected to an output stage formed of a switching amplifier, and an output of the switching amplifier connecting to an output transducer;
a current source for supplying an operating voltage;
a delta voltage generator as a base signal generator for providing a pulse-duration-modulated signal for controlling said switching amplifier;
said delta voltage generator comprising at least one integrator whose integration direction is reversible dependent on an input signal at an input side thereof, said integrator being in interactive connection with a switch at said input side thereof and with a comparison circuit at an output side thereof; and said comparison circuit controlling the switch by which said input signal is supplied at said input side of said integrator dependent on at least one threshold voltage derived from said operating voltage.
an input transducer connected to an amplifier, an output of the amplifier connected to an output stage formed of a switching amplifier, and an output of the switching amplifier connecting to an output transducer;
a current source for supplying an operating voltage;
a delta voltage generator as a base signal generator for providing a pulse-duration-modulated signal for controlling said switching amplifier;
said delta voltage generator comprising at least one integrator whose integration direction is reversible dependent on an input signal at an input side thereof, said integrator being in interactive connection with a switch at said input side thereof and with a comparison circuit at an output side thereof; and said comparison circuit controlling the switch by which said input signal is supplied at said input side of said integrator dependent on at least one threshold voltage derived from said operating voltage.
2. A hearing aid according to claim 1 wherein said input signal of the integrator is switched by the switch for reversing said integration direction at said integrator output side.
3. A hearing aid according to claim 1 wherein said input signal for said integrator is formed of two different DC voltages that can be alternately applied to said input side of said integrator via said switch dependent on said comparison circuit.
4. A hearing aid according to claim 1 wherein said switch comprises a bistable trigger circuit.
5. A hearing aid according to claim 4 wherein said bistable trigger circuit comprises a R/S flip-flop.
6. A hearing aid according to claim 1 wherein said input transducer comprises a microphone, said output transducer comprises an earphone, and said current source comprises a battery.
7. A hearing aid according to claim 1 wherein said comparison circuit comprises a window comparator circuit.
8. A hearing aid according to claim 1 wherein said comparison circuit is supplied with two threshold voltages from a voltage divider connected electrically parallel to said current source which is a battery, and further comprising a series circuit to at least three resistors whose junctions form taps for said threshold voltages.
9. A hearing aid according to claim 1 wherein said integrator comprises an operational amplifier whose output is capacitively connected to an inverting input thereof and whose non-inverting input is supplied with voltage representing half of said operating voltage.
10. A hearing aid according to claim 9 wherein said half of said operating voltage is obtained from a voltage divider connected parallel to said battery, and wherein two resistors whose junction forms a tap for half the amount of the operating voltage are arranged between taps for threshold voltages input to saidcomparison circuit.
11. A hearing aid according to claim 1 wherein said switch alternately connects said input side of said integrator to one or two sides of said voltage source.
12. A hearing aid according to claim 11 wherein said voltage source comprises a battery and said two sides are a plus terminal and a minus terminal.
13. A hearing aid, comprising:
an input transducer connected to an amplifier, an output of the amplifier connected to an output stage, and an output of the output stage connecting to an output transducer;
a current source for supplying an operating voltage;
a delta voltage generator as a signal generator for providing a pulse-duration-modulated signal for controlling said output stage;
said delta voltage generator comprising at least one integrator whose integration direction is reversible dependent on an input signal at an input side thereof, said integrator being in interactive connection with a switch at said input side thereof and with a comparison circuit at an output side thereof; and said comparison circuit controlling the switch by which said input signal is supplied at said input side of said integrator dependent on a voltage derived from said operating voltage.
an input transducer connected to an amplifier, an output of the amplifier connected to an output stage, and an output of the output stage connecting to an output transducer;
a current source for supplying an operating voltage;
a delta voltage generator as a signal generator for providing a pulse-duration-modulated signal for controlling said output stage;
said delta voltage generator comprising at least one integrator whose integration direction is reversible dependent on an input signal at an input side thereof, said integrator being in interactive connection with a switch at said input side thereof and with a comparison circuit at an output side thereof; and said comparison circuit controlling the switch by which said input signal is supplied at said input side of said integrator dependent on a voltage derived from said operating voltage.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP92111013A EP0576700B1 (en) | 1992-06-29 | 1992-06-29 | Hearing aid |
| EP92111013.6 | 1992-06-29 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2099187A1 true CA2099187A1 (en) | 1993-12-30 |
Family
ID=8209759
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002099187A Abandoned CA2099187A1 (en) | 1992-06-29 | 1993-06-25 | Hearing aid |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0576700B1 (en) |
| AT (1) | ATE132682T1 (en) |
| CA (1) | CA2099187A1 (en) |
| DE (1) | DE59204943D1 (en) |
| DK (1) | DK0576700T3 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE69633967T3 (en) * | 1996-12-04 | 2008-10-09 | Phonak Ag | Method and device for supplying energy to a hearing aid |
| CN100337171C (en) * | 2002-05-16 | 2007-09-12 | 广达电脑股份有限公司 | Double frequency pulse wave width modulating and voltage stabilizer |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2908942C3 (en) * | 1979-03-07 | 1982-01-28 | Siemens AG, 1000 Berlin und 8000 München | Device for generating an electrical triangular voltage |
| US4689819B1 (en) * | 1983-12-08 | 1996-08-13 | Knowles Electronics Inc | Class D hearing aid amplifier |
| IL89259A0 (en) * | 1989-02-10 | 1989-09-10 | Avr Communications Ltd | Audio apparatus |
| CH681499A5 (en) * | 1990-10-30 | 1993-03-31 | Ascom Audiosys Ag |
-
1992
- 1992-06-29 AT AT92111013T patent/ATE132682T1/en active
- 1992-06-29 DE DE59204943T patent/DE59204943D1/en not_active Expired - Fee Related
- 1992-06-29 DK DK92111013.6T patent/DK0576700T3/en active
- 1992-06-29 EP EP92111013A patent/EP0576700B1/en not_active Expired - Lifetime
-
1993
- 1993-06-25 CA CA002099187A patent/CA2099187A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| ATE132682T1 (en) | 1996-01-15 |
| DE59204943D1 (en) | 1996-02-15 |
| EP0576700A1 (en) | 1994-01-05 |
| DK0576700T3 (en) | 1996-06-03 |
| EP0576700B1 (en) | 1996-01-03 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |