Circuit and a receiver comprising the circuit

Abstract

A circuit and a receiver comprising the circuit, the circuit is able to either feed a received signal directly to the receiver coil or amplify the signal before transmission to the coil. The circuit receives a supply power and amplifies the input signal if the supply power exceeds a threshold value.

Claims

1. A method of operating a sound generator, the method comprising the steps of: A) receiving an audio signal, B) receiving a supply voltage, C) if the supply voltage does not exceed a threshold voltage, feeding the received audio signal to the sound generator, the received audio signal having a first signal strength, D) if the supply voltage exceeds the threshold voltage: a) feeding the supplied voltage to an amplifier, b) feeding the audio signal to the amplifier, and c) causing the amplified audio signal to be fed to the sound generator, the amplified audio signal having a second signal strength exceeding the first signal strength, where step A) comprises receiving the audio signal on a first and a second input terminal of a circuit also including: a first and a second output terminal, the first and second output terminals connected to the sound generator, and a first and a second switch, where step B) comprises receiving the supply voltage from a power supply, where step C) comprises: the first switch connecting the first input terminal to the first output terminal, and the second switch connecting the second input terminal to the second output terminal, and where step D) comprises: the first switch connecting the first input terminal to an input of a first amplifier or an output of the first amplifier to the first output terminal, and the second switch connecting the second input terminal to an input of a second amplifier or an output of the second amplifier to the second output terminal.

2. An assembly of a sound generator and a circuit, the sound generator comprising a coil having a first and a second coil terminal, the circuit comprising: a first and a second input terminal, a first and a second output terminal, the first output terminal connected to the first coil terminal and the second output terminal connected to the second coil terminal, a first and a second switch, the first switch being configured to either make a first connection or a second connection, the first connection connecting the first input terminal to an input of a first amplifier or to an output of the first amplifier to the first output terminal and the second connection connecting the first input terminal to the first output terminal, and the second switch being adapted to either make a third connection or a fourth connection: the third connection connecting the second input terminal to an input of a second amplifier or to an output of the second amplifier to the second output terminal, when the first switch either connects the first input terminal to the input of the first amplifier or the output of the first amplifier to the first output terminal, and the fourth connection connecting the second input terminal to the second output terminal, when the first switch connects the first input terminal to the first output terminal.

3. An assembly according to claim 2, wherein the circuit further comprises a third and a fourth switch, wherein: the first and third switches are configured to either make a fifth connection or a sixth connection, the fifth connection connecting the first input terminal to the input of the first amplifier and the output of the first amplifier to the first output terminal and the sixth connection connecting the first input terminal to the first output terminal, and the second and fourth switches are adapted to either make a seventh connection or an eighth connection: the seventh connection connecting the second input terminal to the input of the second amplifier and the output of the second amplifier to the second output terminal, when the first and third switches connect the first input terminal to the input of the first amplifier and the output of the first amplifier to the first output terminal, and the eighth connection connecting the second input terminal to the second output terminal, when the first and third switches connect the first input terminal to the first output terminal.

4. An assembly according to claim 2, further comprising: a voltage input terminal connected to voltage supplies of the first and second amplifiers, a controller connected to the voltage input terminal, the controller being configured to control the switches.

5. An assembly according to claim 4, wherein the controller is configured to, when the voltage supplied to the voltage input terminal is below a predetermined voltage: control the first switch to connect the first input terminal to the first output terminal and control the second switch to connect the second input terminal to the second output terminal.

6. An assembly according to claim 4, wherein the controller is configured to, when the voltage supplied to the voltage input terminal is above a predetermined voltage: control the first switch to connect the first input terminal to the input of the first amplifier and the output of the first amplifier to the first output terminal, control the second switch to connect the second input terminal to the input of the second amplifier and the output of the second amplifier to the second output terminal.

7. An assembly according to claim 2, further comprising: a housing defining an inner space, a diaphragm dividing the inner space into at least two chambers, a magnet assembly defining a magnet gap, an armature comprising a portion extending through the magnet gap and a coil tunnel of the coil, the armature being connected to the diaphragm.

8. A circuit for use in the assembly according to claim 2, the circuit comprising: a voltage input terminal connected to voltage supplies of the first and second amplifiers, and a controller connected to the voltage input terminal, the controller being configured to control the switches.

9. A circuit according to claim 8, further comprising a third and a fourth switch, wherein: the first and third switches are configured to either make a fifth connection or a sixth connection, the fifth connection connecting the first input terminal to the input of the first amplifier and the output of the first amplifier to the first output terminal and the sixth connection connecting the first input terminal to the first output terminal, and the second and fourth switches are adapted to either make a seventh connection or an eight connection: the seventh connection connecting the second input terminal to the input of the second amplifier and the output of the second amplifier to the second output terminal, when the first and third switches connect the first input terminal to the input of the first amplifier and the output of the first amplifier to the first output terminal and the eight connection connecting the second input terminal to the second output terminal, when the first and third switches connect the first input terminal to the first output terminal.

10. A circuit according to claim 8, wherein the controller is configured to, when the voltage supplied to the voltage input terminal is below a predetermined voltage: control the first switch to connect the first input terminal to the first output terminal and control the second switch to connect the second input terminal to the second output terminal.

11. A circuit according to claim 8, wherein the controller is configured to, when the voltage supplied to the voltage input terminal is above a predetermined voltage: control the first switch to connect the first input terminal to the input of the first amplifier and the output of the first amplifier to the first output terminal, control the second switch to connect the second input terminal to the input of the second amplifier and the output of the second amplifier to the second output terminal.

Description

(1) In the following, preferred embodiments will be described with reference to the drawing, wherein:

(2) FIG. 1 illustrates the main components of a known receiver, and

(3) FIG. 2 illustrates a switching circuit according to the invention.

(4) In FIG. 1, a standard receiver set-up is seen where a hearing aid or a hearable 10 comprises a microphone 12, a battery 16, a controller 14 and a receiver 100 comprising a housing 102 divided into two chambers 1022 and 1023 by a diaphragm 104. The controller 14 feeds, via input terminals 15 and 16, a signal to a coil 108 comprising a number of windings and defining a coil tunnel 1081. The receiver also comprises a magnet assembly 106 defining a magnet air gap 1061. An armature 17 is fixed to the housing and has a flexible arm extending through the coil tunnel 1081 and the magnet air gap 1061 and which is connected, at an end 121 to the diaphragm 104 via a drive pin 122.

(5) The receiver generates sound by receiving a current from the terminals 15/16, whereby an electrical field is generated within the armature, which makes it move due to the interaction with the magnetic field in the air gap. The movement of the diaphragm generates pressure differences in the chambers, whereby sound is output from a sound outlet 1021. A vent may be provided for ensuring pressure equalization of the back chamber.

(6) The controller may be formed on any technology and implemented as a chip, FPGA, ASIC, controller, DSP or the like. The controller may be monolithic or formed by multiple elements communicating with each other.

(7) Systems of this type are adapted to a single supply voltage from the battery 16. Often, the controller 14 is manufactured to suit the voltage of the battery type preferred. Up until now these Controller/DSP's 14 in the hearing aid industry were constructed for ZnO batteries where the maximum voltage is around 1.5 Volt. New, rechargeable batteries have been developed which provide significantly higher voltages on the order of 3-4.2 Volt (depending on the charging level). Using such batteries with the legacy DSPs would require a voltage conversion, which is inefficient and thus consumes power.

(8) In order to adapt the battery voltage to the processor, a DC conversion may be performed. Actually, some processors even for the usual supply voltages have internal DC conversions to even lower voltages in order to e.g. save power.

(9) Naturally, as high a sound intensity as possible is desired, within limits. Naturally, for a given supply voltage, the impedance of the coil could be reduced (see e.g. EP1617704), such as by decreasing the number of windings. This will decrease the voltage drawn from the battery but will increase the current consumption. There is, however, a limit to the current which the battery can provide. Also, a very low impedance will increase the noise level at lower frequencies, which is problematic in that many persons with hearing loss actually has OK hearing at the lower frequencies.

(10) Thus, when no higher voltage is available than that suitable for the controller, so that the output of the controller would be as high as an output of an amplifier fed with the voltage available, the controller output may be fed directly to the coil as usual.

(11) However, when a higher supply voltage is available, the output of the controller may be amplified before transmission to the coil. In this manner, a higher sound output may be obtained. Thus, when the supply voltage exceeds a predetermined voltage, an amplifier circuit may be used.

(12) A situation catering for this may be seen in FIG. 2, where a circuit 40 is provided having two input terminals, 42 and 44, and two output terminals, 46 and 48, outputting a signal to the receiver 100, or rather the coil thereof. Actually, the circuit 40 may be provided inside the receiver 100, so that the inputs 42/44 are connected to or embodied as the inputs 15/16.

(13) Four switches, 52, 54, 56 and 58, are provided, as well as transistors 62, 64, 66 and 68 forming two amplifier elements (62/66 combined and 64/68 combined) powered by a supply voltage 60 and ground.

(14) The operation of the circuit 40 is to, when the supply voltage available is lower than a threshold voltage, operate the switches to be in the position illustrated, so that the inputs 42/44 are fed directly to the outputs 46/48 and to the receiver coil.

(15) However, when the supply voltage 60 exceeds the threshold, the switches are brought to their other position, so that the signal from the input 42 is fed to the amplifier formed by transistors 62/66 and thereafter to the output 56 and the receiver, where the signal received on the input 44 is amplified in 64/68 and fed to the receiver via output 58. In this situation, the higher supply voltage will bring about a higher sound output intensity.

(16) Then, the same receiver, with this circuit, may be used for different battery technologies, and/or it may change its mode of operation when e.g. a battery becomes depleted. It may be preferred that the default operation of the circuit is that seen in FIG. 2, where the input into the circuit is fed directly to the outputi.e. the operation of a standard receiver.

(17) Naturally, the four switches may be reduced in number. Thus, the switches 52/54 may be removed and the terminal 44 permanently connected to both conductors which the switches 52 and 54 switch between. Then, the signal received on the terminal 44, for example, is always fed into the input of the amplifier and toward the switch 58. The switch 58 then still decides which signal to feed to the terminal 48.

(18) Alternatively, the switches 56/58 may be removed and the terminal 48 connected to both the amplifier output and the conductor toward the switch 52/54. Then, the switch 52/54 decides where to forward the signal received and thus which signal is eventually fed to the terminals 46/48.

(19) A separate controller 50 may be provided for controlling the switches. Alternatively, a controller provided outside of the circuit 40, such as within the receiver 100 or in any other position.

(20) Naturally, other types of amplifier circuits may be used, such as operational amplifiers. Also, or alternatively, circuitry may be provided for recreating the signal output of the circuit, such as to recreate pulses therein. The pulse rise- and fall times may be altered by e.g. the amplification or cables provided between the DSP (which may be provided in a BTE) and the circuit (which may be provided in an ITC) and preferably are brought back to the desired values or intervals before feeding to the coil.

(21) Usually, the signal fed to the coil and thus the inputs 42/44 is pulse width modulated (PWM) or pulse density modulated (PDM). Then, preferably the transistors are fast enough to have a good pulse rise- and fall time, so as to not affect the modulation and efficiency.

(22) In some receivers configured to receive signals from low power consumption devices, electronics may already be provided in the receiver for power conversion. These electronics may be combined with the circuit 40.

(23) The circuit or receiver can either have a fixed behaviour with respect to supply voltage changes, such as operate in one mode when the supply voltage is below a threshold voltage and in another when the supply voltage exceeds the threshold voltage. In fact, when the supply voltage exceeds the threshold voltage so that it is possible to operate the amplifiers, it may still be decided to feed the signal directly through the circuit. Thus, a controlling signal may be received (wired or wireless) which controls the operation of the circuit, at least when the supply voltage is high enough for the circuit to have a choice to use the amplifiers or not.

(24) Naturally, the circuit/receiver can be freely programmable, such as by a DSP or a user interface (see e.g. EP2663095 and EP1331835).

(25) In the situation where the higher supply voltage is available, the amplifier may additionally be configured to filter the signal received on the input and fed to the output. Usually, this filtering, if performed at all, is performed by an amplifier feeding the signal to the receiver.

(26) This filtering may be the filtering usually performed by other amplifiers in usual hearing aids or hearables, such as to remove certain frequency intervals, attenuation of certain frequency intervals (e.g. for compensating for a resonance frequency) or amplifying certain frequency intervals.

(27) It may be desired to under all circumstances amplify the signal received on the terminals 42/44, whereby an additional amplifier may be provided, or the signal received may be fed into the processor 50 for amplification also.

(28) Identification of the receiver or circuit (see e.g. U.S. Pat. No. 9,426,587) may be used in order to adapt the signal fed thereto either to the terminals 42/44 or for e.g. controlling parameters of the amplification and/or a filtering or the like as described above. This identification may be output on one of the existing wires (for the terminal 42, 44 or 60) or in a separate cross section such as a separate wire or wirelessly.

(29) This filtering may be an attenuation of the signal, such as within a predetermined frequency interval in order to control the power consumption. In many instances it is desired to limit the maximum current drawn from the power source. Usually, the lower frequency portion of the signal contains the most power, so that if the current limit is approaching, it may be desired to attenuate the lower frequency portion of the signal while maintaining the higher frequency portion thereof.

(30) Thus, a current determination may be made in the circuit or in the receiver, which feeds a signal to the processor for this controlling.

(31) Exceeding the maximum current of a battery may shorten the lifetime thereof or cause the battery voltage to become unstable (dips).

(32) Providing a controller within this circuit also allows a portion of the processing of other controllers/DSPs to be distributed to the circuit, such as power supply stabilization, identification of the receiver/circuit or further amplification.

(33) In some situations, multiple, such as two, receivers are desired. This may be to simply increase the sound intensity. Alternatively, a tweeter and a woofer may be provided handling either end of the frequency range.

(34) One circuit 40 could be used for two receivers. In this situation, both receivers are connected, in series or parallel, between the output terminals 46/48.

(35) Alternatively, a separate circuit 40 may be provided for each receiver. In this situation, the above filtering, amplification, power management and the like may be handled separately for each receiver.

(36) It may be desired, when separate circuits are provided, to control the gains of the circuits to e.g. match the vibrations or the vibration frequencies of the two receivers to obtain a vibration suppression over a certain frequency range.

(37) Naturally, the circuit may be autonomous in the sense that it is hard programmed to operate in a particular fashion, such as in the simple case where the switches are operated only on the basis of the supply voltage and the threshold voltage.

(38) However, the circuit offers, as mentioned above, a wide range of functionality and adaptation to different situations, different supply voltages and the like.

(39) Thus, the settings of the controlling of the switches, the threshold voltage, the amplification, the filtering and the like of the amplifiers may be stored in a memory provided in the receiver, for example. Such settings could be fed to the memory or a controller connected thereto from outside of the receiver via a data input. This data input may be a wireless connection or an input wire which, naturally, may be a conductor used also for other purposes, such as for supplying power to the receiver. Thus, this configuration data may be received by the circuit over the wire 60.

(40) Also, this configuration data may be received by the circuit and stored intermittently or permanently, such as in a ROM, FPGA or the like, such as when using fuses, which are burned to stay in a permanent state.