WO2000031891A1 - Procede destine a un systeme de boucle d'induction a distance, systeme de boucle d'induction a distance et amplificateur correspondant - Google Patents

Procede destine a un systeme de boucle d'induction a distance, systeme de boucle d'induction a distance et amplificateur correspondant Download PDF

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Publication number
WO2000031891A1
WO2000031891A1 PCT/DK1999/000650 DK9900650W WO0031891A1 WO 2000031891 A1 WO2000031891 A1 WO 2000031891A1 DK 9900650 W DK9900650 W DK 9900650W WO 0031891 A1 WO0031891 A1 WO 0031891A1
Authority
WO
WIPO (PCT)
Prior art keywords
amplifier
teleloop
signal
pulse width
output
Prior art date
Application number
PCT/DK1999/000650
Other languages
English (en)
Inventor
Leif JØRGENSEN
Original Assignee
Logia A/S
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Logia A/S filed Critical Logia A/S
Priority to AU13754/00A priority Critical patent/AU1375400A/en
Priority to EP99972807A priority patent/EP1138129A1/fr
Publication of WO2000031891A1 publication Critical patent/WO2000031891A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
    • H03F3/20—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers
    • H03F3/21—Power amplifiers, e.g. Class B amplifiers, Class C amplifiers with semiconductor devices only
    • H03F3/217—Class D power amplifiers; Switching amplifiers
    • H03F3/2171—Class D power amplifiers; Switching amplifiers with field-effect devices
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03F—AMPLIFIERS
    • H03F2200/00—Indexing scheme relating to amplifiers
    • H03F2200/351—Pulse width modulation being used in an amplifying circuit
    • 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
    • H04R25/55—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception using an external connection, either wireless or wired
    • H04R25/554—Deaf-aid sets, i.e. electro-acoustic or electro-mechanical hearing aids; Electric tinnitus maskers providing an auditory perception using an external connection, either wireless or wired using a wireless connection, e.g. between microphone and amplifier or using Tcoils

Definitions

  • the invention relates to teleloop systems, particularly to amplifiers for amplification of signals, which are supplied to a teleloop and to the method of amplification.
  • Teleloop systems are well known assistive listening devices used for generating a magnetic signal, which can be picked up by a telecoil in a hearing aid worn by a hearing impaired person or by a tele-receiver. Teleloops are commonly used in public facilities, such as churches, railway stations and the like.
  • a typical teleloop system comprises a teleloop cable and an amplifier adapted to amplify an input signal from a microphone or the like.
  • the purpose of the amplifier is to make a suitable amplification of the signal supplied to the amplifier in order to generate a magnetic field of a magnitude sufficient for the receivers, e.g. the coil in the hearing aid, to sense this signal and process this further for output to the user.
  • the impedance in the teleloop cable is constituted by a self-induction connected in series with a resistance.
  • a linear amplifier When a linear amplifier is connected to such impedance an output effect corresponding to the output voltage multiplied with the output current is expected.
  • a blind effect is disposed within the amplifier.
  • a significant part of the effect supplied to the amplifier is therefore converted to heat in the amplifier. This requires a significant cooling surface area and a power supply having a capacity significant larger than the necessary output. The result is a high power consumption and high production costs.
  • One objective of the present invention is to provide a method for amplifying a signal in a teleloop system, which will make it possible to lower the production costs and the power consumption of the teleloop system.
  • a further objective of the present invention is to provide a teleloop system, where the production costs and the power consumption of this is lowered.
  • a still further objective of the present invention is to provide an amplifier for a teleloop system, where the production costs and the power consumption of this is lowered.
  • the amplification has been achieved in the time domain and the heat generation will remain limited since the blind effect disposed in the amplifier is reduced. By this it is possible to dimension the cooling surface area smaller. The capacity of the power supply can at the same time be reduced. Both these factors contribute to lower production costs. Furthermore the operation costs are reduced due to the lower power consumption.
  • the invention further lead to a possibility of increasing the output from the teleloop system at a maintained power consumption and hereby allowing a hearing aid user to reduce gain in his or her hearing aid with possible audible benefits such as lowering of noise and distortion.
  • the second objective is achieved by means of a teleloop system as defined in claim 3.
  • a teleloop system as defined in claim 3.
  • the third objective is achieved by means of an amplifier as defined in claim 5.
  • FIG. 1 is a schematic drawing showing a preferred embodiment of the amplifier according to the invention.
  • FIG. 2 is a schematic drawing showing the frequency /voltage characteristics of the amplifier
  • FIG. 3 is a schematic drawing showing the principles of the PWM generator
  • FIG. 4 is a diagram showing a PWM signal.
  • the amplifier comprises a highpass filter 1 followed by a lowpass filter 2.
  • the highpass filter 1 is of a variable type controlled by a frequency compensation control 12, which preferably is automatic and which gets input from a current transducer 7 at the induction loop or the teleloop 6.
  • the signal from the lowpass filter 2 is mixed with a filtered (filter 3) feedback signal 4.
  • the mixed signal is lead to an amplifier 11 and afterwards to a PWM generator 10 and to a driver 9 before the output stage 8 is reached.
  • the signal is lowpass filtered (filter 5 and led to the induction loop 6.
  • the feedback signal 4 is obtained from the output before the lowpass filtering 5. This feedback signal is likewise led to the pulse width modulation generator 10.
  • the purpose of the amplifier is to generate current with constant amplitude and a defined frequency response at a given load, the teleloop or induction loop.
  • the teleloop is a cable arranged as a single loop coil.
  • the cable can be equalized by an impedance (Z) consisting of a self-induction (L) and a resistance (R) connected in series. If a current is applied to the impedance the characteristics as shown in FIG. 2 appears, f, and f u are the lower and the upper border frequency, respectively and f o is the border frequency of the teleloop.
  • f 0 is determined by L and R, which are dependent on the area of the teleloop and the cross section area of the cable, and may therefore vary in the entire bandwidth of the amplifier.
  • the amplifier comprises three main elements, which are a signal adaptation part, a regulation part and an output stage.
  • the signal adaptation part is the signal adaptation part:
  • Tone control The loop loads the output stage.
  • the frequency characteristic of the output stage can therefore not be completely linear between f, and f u .
  • the tone control is used for correcting this error.
  • a linear characteristic is necessary for achieving optimal f 0 correction.
  • the tone control is further used for tone regulation of the input signal.
  • f 0 correction The circuit forms a variable treble raising element. The knee point frequency f 0 is determined by a digitally controlled potentiometer. f u of the amplifier is likewise determined by this circuit.
  • Attenuator A voltage-controlled attenuator is used for protection purposes (temperature and excessive current)
  • a filter is applied serving the purpose of damping the input signal to a level where the output filter is not oscillating.
  • a micro-controller, an AD converter and a tone generator constitute the controller.
  • the controller sends a sine signal in the loop and the ADC measures the resulting current. Based on measurements at different frequencies the necessary correction is carried out.
  • a crystal controlled oscillator generates a basic clock signal for the PWM generator.
  • a logic circuit divides the frequency to the desired switching frequency.
  • a schematic embodiment of the generator is shown in FIG 3.
  • Al is a operation amplifier coupled as a integrator and A2 is a comparator , the output of which represents the output of the amplifier.
  • the coupling reacts as a common inverting amplifier coupling, as Al will adjust its output voltage at OV between the + and - inputs.
  • the output signal will shift at a frequency corresponding to the clock frequency. If a positive signal is applied to Rl (Uin) Uin is mixed with the clock signal. Al will try to maintain OV between the inputs. Hereby the triangle signal is displaced in negative direction. Most of the triangle signal will be below OV. The negative output pulses will therefore be broader than the positive output pulses.
  • R3 creates a coupling the mean value of the output signal is proportional with the input signal.
  • the triangle signal appears from FIG. 4.
  • the output stage :
  • Push-pull coupling Two FET transistors are arranged in a +- supplied push- pull coupling.
  • Output filter the filter functions as a demodulator.
  • the PWM signal is integrated and the amplified input signal is regenerated.
  • the filter furthermore removes noise.
  • the output current is used for determining the output voltage, which is used for f 0 correction.
  • Temperature measurement The temperature is measured. At to high temperature the signal is damped and the temperature is reduced.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Amplifiers (AREA)

Abstract

L'invention concerne un système permettant d'amplifier un signal dans un amplificateur destiné à un système de boucle d'induction à distance. Ce procédé consiste à émettre un signal de sortie au moyen d'une modulation d'impulsions en durée. L'invention concerne également un système de boucle d'induction à distance comprenant un câble de boucle d'induction à distance, un amplificateur relié à ce câble et un dispositif à l'intérieur de l'amplificateur afin d'émettre un signal de sortie au moyen d'une modulation d'impulsions en durée.
PCT/DK1999/000650 1998-11-24 1999-11-24 Procede destine a un systeme de boucle d'induction a distance, systeme de boucle d'induction a distance et amplificateur correspondant WO2000031891A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU13754/00A AU1375400A (en) 1998-11-24 1999-11-24 A method for use in a teleloop system, a teleloop system and an amplifier for a teleloop system
EP99972807A EP1138129A1 (fr) 1998-11-24 1999-11-24 Procede destine a un systeme de boucle d'induction a distance, systeme de boucle d'induction a distance et amplificateur correspondant

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DKBA199800442 1998-11-24
DK199800442U DK199800442U3 (da) 1998-11-24 1998-11-24 Teleslyngeforstærker

Publications (1)

Publication Number Publication Date
WO2000031891A1 true WO2000031891A1 (fr) 2000-06-02

Family

ID=8156719

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/DK1999/000650 WO2000031891A1 (fr) 1998-11-24 1999-11-24 Procede destine a un systeme de boucle d'induction a distance, systeme de boucle d'induction a distance et amplificateur correspondant

Country Status (4)

Country Link
EP (1) EP1138129A1 (fr)
AU (1) AU1375400A (fr)
DK (1) DK199800442U3 (fr)
WO (1) WO2000031891A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1250026A1 (fr) * 2001-04-11 2002-10-16 Phonic Ear, Inc. Transfer de données courte portée pour dispositifs de communication
WO2004034738A1 (fr) * 2002-10-09 2004-04-22 Estron A/S Systeme de boucle d'induction
EP1777644A1 (fr) * 2005-10-20 2007-04-25 Oticon A/S Système et procédé d'actionnement d'antenne

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5276910A (en) * 1991-09-13 1994-01-04 Resound Corporation Energy recovering hearing system
EP0576701A1 (fr) * 1992-06-29 1994-01-05 Siemens Audiologische Technik GmbH Prothèse auditive
EP0843427A1 (fr) * 1996-10-31 1998-05-20 AB Transistor Dispositif d'atténuation de distorsions harmoniques pour un signal à transmettre
US5812598A (en) * 1993-07-02 1998-09-22 Phonic Ear Incorporated Hearing assist system employing time variant modulation transmission to hearing aid

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5276910A (en) * 1991-09-13 1994-01-04 Resound Corporation Energy recovering hearing system
EP0576701A1 (fr) * 1992-06-29 1994-01-05 Siemens Audiologische Technik GmbH Prothèse auditive
US5812598A (en) * 1993-07-02 1998-09-22 Phonic Ear Incorporated Hearing assist system employing time variant modulation transmission to hearing aid
EP0843427A1 (fr) * 1996-10-31 1998-05-20 AB Transistor Dispositif d'atténuation de distorsions harmoniques pour un signal à transmettre

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1250026A1 (fr) * 2001-04-11 2002-10-16 Phonic Ear, Inc. Transfer de données courte portée pour dispositifs de communication
WO2004034738A1 (fr) * 2002-10-09 2004-04-22 Estron A/S Systeme de boucle d'induction
EP1777644A1 (fr) * 2005-10-20 2007-04-25 Oticon A/S Système et procédé d'actionnement d'antenne
AU2006230661B2 (en) * 2005-10-20 2010-09-02 Oticon A/S System and method for driving an antenna
AU2006230661B8 (en) * 2005-10-20 2010-12-23 Oticon A/S System and method for driving an antenna
US7903832B2 (en) 2005-10-20 2011-03-08 Oticon A/S System and method for driving an antenna

Also Published As

Publication number Publication date
EP1138129A1 (fr) 2001-10-04
AU1375400A (en) 2000-06-13
DK199800442U3 (da) 1999-01-22

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