DE102016224834A1 - Method and circuit arrangement for operating a headphone - Google Patents

Abstract

The present invention relates to a method and a circuit arrangement for operating a headphone, in particular an in-ear headset, by a user together with a terminal, wherein it is provided in particular that the electrical resistance of at least one loudspeaker of the headphone is determined (500-510 ) and is detected (520) based on the determined resistance, whether the headset is currently located in or on the ear or outside or away from the user's ear

Description

The invention relates to a method and a circuit arrangement for operating a headset or a headset, in particular an in-ear headphone or a corresponding clothing, according to the preambles of the respective independent claims. The present invention also relates to a computer program, a machine-readable data carrier for storing the computer program and an electronic control unit, by means of which the method according to the invention can be carried out.

State of the art

So-called "in-the-ear" or "in-ear" headphones are often used in mobile terminals, e.g. in mobile phones, mobile music players or portable computers, e.g. Laptop or tablet computers. The loudspeakers I use are mostly membrane loudspeakers driven by low-impedance magnetic coils.

The respective mobile terminal and the headphone interact in such a way that it is first detected whether there is an effective electrical connection between the terminal and the headset, and that at a detected electrical connection present in the terminal control or driver program an audio connection between an audio application and the headset. The control of the audio application and corresponding functions such as volume control, selection of an audio file or the termination of a telephone connection is usually carried out by means arranged on the terminal controls such as buttons, touchscreen icons or the like.

Out US 2014/0003616 A1 For example, an apparatus and method for detecting AC electrical resistance (impedance) of a headset for an electronic terminal is disclosed. On the basis of the detected resistance, or by means of a signal or a correspondingly derived signal signature, which is defined by a respectively present impedance characteristic of a load applied to the terminal, is between the presence of an electrical connection of the terminal with a headphone or the Existence of an electrical connection of the terminal with a self-amplified output device, which has a "line-level" input, distinguished. In the latter case, a corresponding "line-out" amplifier and a suitable insulation resistance are activated at the terminal, by means of which the required for a line-out high voltage level or the correspondingly required high capacitive load can be provided or driven.

Disclosure of the invention

The method proposed here or the circuit arrangement for operating a headphone or a headphone with a terminal concerned here, in particular a corresponding in-ear headphones, the idea is based on the electrical resistance, in particular the electrical AC resistance (impedance) To determine at least one speaker of an in-ear headphone, whether the headset is in the ear or outside the ear of a user.

The method is based on the technical effect that the electrical resistance or the alternating electrical resistance (impedance) of a loudspeaker or both loudspeakers in an in-ear loudspeaker caused by the sound pressure-induced acoustic attenuation of the loudspeaker membrane and / or by the inner chamber acoustic attenuation / Resonance effects, indirectly affects the flowing through the speaker electric current back and therefore influenced or changed accordingly.

The said effect can be further exploited to depending on the respective headset type or the speaker used therein and the respective user or the spatial configuration of his ear interior, signatures for the impedance history in the ear and outside of the ear arranged headphones generate, by means of which the detection of the affected state of use of the headphone can be performed even more precise and thus more reliable.

An embodiment of the proposed method provides that the electrical current flowing through at least one loudspeaker of the headset is detected as a function of the time that time-dependent resistance values are calculated from the detected electrical current values using a specifiable electrical drive voltage such that the time-dependent resistance values are determined by means of Fourier signals. Transformation are converted into frequency-dependent resistance values, and that it is detected from the resulting frequency-dependent resistance values, whether the headset is arranged in or on the ear or outside or away from the user's ear.

According to a further aspect, it may be provided that a frequency-dependent resistance value is determined from the said frequency-dependent resistance values Frequency-dependent signature for the resistance profile is generated when in and / or at the ear and outside of the ear arranged headphones, on the basis of which said detection is performed.

• - Der Kopfhörertyp;
• - der Benutzer;
• - die Beendigung oder Pausierung des Abspielens einer Audiodatei mittels des Endgerätes;
• - die Erfassung der Beendigung eines Telefonats mittels einer den Kopfhörer aufweisenden Freisprechanlage oder das Umschalten in einen Freisprechmodus;
• - die Zuführung zweier Kanalbeiträge eines Stereo-Audiosignals an nur einen Lautsprecher.

In addition, it can be provided that one or more of the following conditions or quantities is additionally recognized by means of the frequency-dependent signature:

• - the headphone type;
• - the user;
• the termination or pausing of the playback of an audio file by means of the terminal;
• - the detection of the termination of a call by means of a headset having handsfree or switching to a handsfree mode;
• - The supply of two channel contributions of a stereo audio signal to only one speaker.

It can also be provided that the said recognition method is trained and thereby the recognition rate and / or the recognition quality are optimized or improved.

Furthermore, provision can be made for only relative resistance changes to be taken into account in the aforementioned detection, so that absolute values can not falsify the recognition result.

The proposed method makes it possible, even without additional sensors, to automatically interrupt or end the playback of an audio file in the terminal if it is determined that the headset is no longer on or in the ear of the user.

When operating a telephony terminal can be alternatively or additionally provided in the proposed method that the terminal is automatically transferred to the handsfree operation or switched when recognizing that the headset is no longer on or in the ear of the user. This makes it possible that a telephone call already executed can be continued without interruption even when the headset falls out of the user's ear.

According to one embodiment of the proposed circuit arrangement, this has a load resistor electrically connected to at least one loudspeaker, a first amplifier for providing a bias voltage, so that a load voltage drops across the load resistor, and an A / D converter for detecting the resistance of the at least one loudspeaker.

In the proposed circuit arrangement can also be provided that supplied by two speakers voltage signals are supplied by means of a multiplexer only a single A / D converter.

It can also be provided that voltage signals supplied by two loudspeakers and by a microphone are fed by means of a multiplexer to a single A / D converter.

Overall, the method or the circuit arrangement thus make possible a more intuitive or user-friendly operation of a headphone concerned here as well as a reduction of the energy consumption of an energy store (for example battery or rechargeable battery), in particular of a mobile terminal.

The computer program according to the invention is set up to carry out each step of the method, in particular if it runs on a computing device or a control device. It allows the implementation of the method according to the invention on an electronic control unit, without having to make structural changes to this. For this purpose, the machine-readable data carrier is provided on which the computer program according to the invention is stored. By loading the computer program according to the invention onto an electronic control unit, the electronic control unit according to the invention is obtained, which is set up to control a headphone or a terminal operated with a headphone by means of the method according to the invention.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

list of figures

• 1 shows a used in mobile phones for the operation of a headphone according to the prior art circuitry.
• 2 shows a first embodiment of a circuit arrangement according to the invention.
• 3 shows a second embodiment of a circuit arrangement according to the invention.
• 4 shows exemplary resistance measurement results according to the method of the invention.
• 5 shows an embodiment of the method according to the invention with reference to a flowchart.

Description of exemplary embodiments

According to a in US 2014/0003616 A1 The approach described is the connecting a headset with a terminal, in this case a conventional (not shown here) mobile phone, based on a in 1 detected circuitry detected. The circuit shown is implemented in the terminal in the present example, but may alternatively also be partially or totally integrated in the headset. The circuit is equipped with a stereo pair of speakers located on the headphone 100 as well as with a likewise arranged on the headphones microphone 105 electrically connected. In the 1 shown microphone / speaker combination is often used as a handsfree device for a mobile device, such as a smartphone.

The electrical connection of the terminal with the headphone by means of a conventional, four-pin connector with cables 110 , each with a live line 115 . 120 for the two speakers 100 , a live wire 125 for the microphone 105 and three interconnected ground lines 130 both for the speakers 100 as well as for the microphone 105 ,

The circuit includes one with the live line 125 of the microphone 105 connected analog / digital (A / D) converter 135, whose output signal by the dashed line 145 is indicated. Furthermore, the circuit includes one with the live wires 115 . 120 of the speaker pair 100 connected digital / analog (D / A) converter 140, whose output signal through the dashed line 150 is indicated. In the present example, the two converters 135 . 140 implemented in the mobile terminal in a respective CODEC (encoder / decoder) of the terminal. It should be noted that today's CODECs usually provide a variety of input and output channels and the 1 for simplicity's sake only has the few channels shown here.

In the 1 In addition, the circuit shown comprises a conventional bias supply 155 for the microphone supplied by a first amplifier (not shown) 105 with resistor in series 156 and with earth potential 158 connected bias voltage source 157 , The signal supplied by the microphone 105 is also by means of a first amplifier 160 strengthened. Furthermore, the circuit comprises a second amplifier 165 for signal amplification of a supplied by the D / A converter 140, to the pair of speakers 100 transmitted audio signal. The second amplifier 165 includes, as usual, two amplifiers 170 . 175 for the two audio channels 115, 120.

Compared to the prior art, the inventive method or the circuit arrangement based on the generation of a (control) signal on the basis of a current flowing through the coil of at least one headphone speaker electrical current. From a suitably generated signal, suitable features or signatures are extracted or changes in the electrical resistance or the impedance are detected in order to trigger predefinable actions at the terminal.

According to the in 2 shown first embodiment of the circuit arrangement according to the invention comprises the live line 200 of a loudspeaker 205 , in addition to the in 1 shown circuit, a shunt resistor 210 , It should be noted that in 2 for with in 1 functionally identical circuit components identical reference numerals are used. Due to a likewise additionally provided and supplied by said, not shown first amplifier bias voltage or drive voltage V _DRIVE 212 falls here on the shunt resistor 210 a shunt voltage V _SHUNT 215. The by means of two capacitors 220 galvanically decoupled shunt voltage V _SHUNT 215 becomes an additional amplifier 225 fed and the corresponding amplified voltage signal finally fed to an additional A / D converter 230, which in the present embodiment as a separate for the resistance detection of the speaker 205 provided auxiliary converter ("Aux Audio A / D converter") is set up. This auxiliary converter 230 is preferably capable of digitizing the entire bandwidth of the audio signal.

It should be noted that the described converter function can also be additionally implemented in the existing A / D converter 135. In addition, it is worth noting that even for the speaker 235 one the circuit components 210 to 230 appropriate evaluation or evaluation logic can be provided with a corresponding separate shunt resistor.

Alternatively, two separate A / D input channels may be present, but you can make use of that, for example, in today's smartphones or built-in sound cards there are often already several audio input channels, by means of which in a conventional manner analog Audio signals can be converted by sampling into digital signals.

In 3 a second embodiment of the circuit arrangement according to the invention is shown, in which according to the 1 only a single A / D converter 135 is provided. In doing so, those from the speaker 205 and supplied to the microphone voltage signals by means of a multiplexer, ie, in a per se known time division multiplex method, the single A / D converter 135, ie, in contrast to 2 without the requirement of an auxiliary converter shown there 230 , With an extended multiplexer, a signal of the second speaker can be detected via another shunt resistor and fed to the single A / D converter.

Similar to in 2 is also in 3 a driver voltage V _DRIVE 212 is provided, wherein one of the 2 corresponding shunt resistance 300 also a shunt voltage 303 drops. By branch lines 305 , 307, 310 and their interaction with a 4-to-2 multiplexer (MUX) analogous to the present embodiment 320 , The microphone signal in the time division multiplex method, the only single amplifier 160 and the only single A / D converter 135 are supplied. By means of the two capacities 315 becomes the multiplexer 320 from the second amplifier 160 galvanically isolated.

It should be noted that in this embodiment also for the second speaker 235 a separate or separate shunt resistor R _{SHUNT is} provided, wherein the corresponding voltage signal would also be supplied to the A / D converter 135 by means of a multiplexer. However, in this embodiment, the multiplexer would have to be formed as a channel-wise extended 6-to-2 multiplexer instead of the mentioned 4-to-2 multiplexer 320.

A disadvantage of the second embodiment over the first embodiment is that the microphone 105 during the course of detection of the resistance or the impedance of the speakers 205 . 235 at least temporarily unavailable.

The following is based on the 4 an embodiment of the method according to the invention described. In this case, the electrical current I _SPK flowing through either one or both loudspeakers of the headset is calculated on the basis of ohmic law, in the time domain, according to the known relationship I _SPK (t) = V _SHUNT (t) / R _SHUNT . Since the driver voltage V _DRIVE 212 provided by said first amplifier can be predefinable and therefore assumed to be known, the instantaneous speaker impedance Z _SPK (t) can be calculated according to the following relationship: Z _SPK (t) = V _DRIVE (t) / I _SPK (t). In this case, the size Z _SPK (t) a time dependent signal is such that in per se known manner by means of "Fast-Fourier" transformation (FFT) of the time-dependent signal Z _SPK (t) a frequency-dependent impedance signal Z _SPK (f) according to the relationship Z _SPK (f) = fft (Z _SPK (t)) can be calculated by means of which it can be determined whether the headphone is currently in the ear or outside the ear of the respective user.

It should be noted that the described approach with the Fourier transform (FFT) requires that a time-dependent audio signal is present at the respective loudspeaker or loudspeaker pair and that the said determination of the headphone usage state can not be performed when at the Headphones no corresponding audio signal is present. Therefore, it can alternatively be provided in the method that only those frequency ranges or frequency lines ("frequency bins") resulting in the FFT are evaluated whose signal strength exceeds an empirically predeterminable threshold value. This can be achieved by separately _subjecting the loudspeaker current I _SPK (t) and the drive voltage V _DRIVE (t) to an FFT and evaluating only frequency lines satisfying the following condition: V _DRIVE (f)> V _min , and thus only for these frequency lines, the impedance is determined in the manner described.

In order to solve the above problem due to the FFT in situations where no audio signal is applied to the speakers, e.g. if music is not yet played on the terminal, but an appropriate player program has already been opened or started, or in situations in which no music or the like is played at all, it can be provided that a test signal is transmitted to one or both loudspeakers, eg an inaudible to the user ultrasonic signal in the frequency range of about 20 kHz in order to determine the said operating or use state of the headphone in such situations in the described manner. Such a high-frequency signal can also be output in addition to an existing audio signal, since thereby the impedance change can be detected even faster and / or more precisely.

It should also be noted that in the operation of the headphone by the continuous playback of audio signals, such as music tracks, most or even all possible frequency lines are covered by the drive voltage V _DRIVE , so that in the entire frequency range impedance values Z _SPK (f) are determined can.

In 4 is for a headphone speaker a typical, measured impedance curve | Z | in the unit [Ω] as a function of the current frequency f in the unit [Hz] in the frequency range between 1 kHz and 20 kHz. The curve 400 corresponds to the situation of an in-ear headphones arranged in the ear of a user and the curve 405 the situation of the same in-ear headphones, but outside the ear. As you can see, the two curves are different 400 . 405 both in terms of amplitude and frequency dependence significantly.

In 5 an embodiment of the method according to the invention is illustrated with reference to a flow chart. In step 500 First, a current value of said size I _SPK (t) is detected. In step 505 from this, the calculation of the impedance Z _SPK (t) based on the ohmic law, wherein the predetermined driver voltage V _DRIVE (t) 510 is taken into account. In step 515 the said FFT transformation takes place, from which the quantity Z _SPK (f) results. The size Z _SPK (f) is determined according to step 520 in fixed time steps of duration 0.1s or longer, each time considering changes of this magnitude, eg ΔZ _SPK (f) = Z _SPK (f) (t) -Z _SPK (f) (t-Δt)).

• - Ermittlung des Kopfhörertyps, z.B. ob es sich um einen passiven oder aktiven Kopfhörer handelt, wobei der zulässige Wertebereich der genannten Größe Z_SPK entspricht;
• - Ermittlung der Person des Benutzers, wobei der zulässige Wertebereich wiederum der genannten Größe Z_SPK entspricht;
• - Erfassung der Beendigung bzw. Pausierung des Abspielens z.B. eines Musiktitels, wobei der zulässige Wertebereich gleich der genannten Änderung der Größe Z_SPK, d.h. dem Wert ΔZ_SPK, entspricht;
• - Erfassung der Beendigung eines Telefonats mittels einer den Kopfhörer aufweisenden Freisprechanlage oder des Umschaltens in den Freisprechmodus, wobei der zulässige Wertebereich wiederum der genannten Änderung der Größe Z_SPK, d.h. dem Wert ΔZ_SPK, entspricht;
• - Zuführung der beiden Kanalbeiträge eines Stereo-Audiosignals an nur einen Lautsprecher, d.h. sozusagen unter Bildung eines Mono-Audiosignals, wenn erkannt bzw. ermittelt wurde, dass momentan nur einer der beiden Kopfhörer bzw. Lautsprecher im Ohr des Benutzers angeordnet ist, wobei der zulässige Wertebereich der genannten Änderung der Größe Z_SPK eines einzelnen Kanals, d.h. dem Wert ΔZ_SPK eines einzelnen Kanals, entspricht.

By recording the impedance or corresponding, frequency-dependent signature as well as its change over time, the following operating conditions or operating variables can be determined:

• - Determining the type of headphone, for example, whether it is a passive or active headphone, the permissible value range of said size Z corresponds to _SPK ;
• - Determination of the person of the user, wherein the permissible value range in turn corresponds to said size Z _SPK ;
• Detecting the termination or pausing of the playback, for example, of a song, the permissible value range being equal to said change of the quantity Z _SPK , ie the value ΔZ _SPK ;
• - Recording the termination of a call by means of a headset having handsfree or switching to handsfree mode, the allowable range of values in turn the said change in size Z _SPK , ie the value .DELTA.Z _SPK corresponds;
• - Supplying the two channel contributions of a stereo audio signal to only one speaker, ie, so to speak, to form a mono audio signal when detected or determined that currently only one of the two headphones or speakers is located in the user's ear, the permissible Range of values of said change in the size Z _{SPK of} a single channel, ie the value .DELTA.Z _{SPK of} a single channel corresponds.

Since the resulting absolute values of the impedance depend on the exact loudspeaker type and therefore vary from headphone to headphone, it can additionally be provided that the described evaluation method is trained and thus optimized for a specific, present type of headphone. Alternatively, it may be provided in this context that the evaluation method takes into account only relative impedance changes, so that the absolute values have no influence on the evaluation result.

The method described can be implemented in the form of a control program for an electronic control unit for controlling a terminal concerned here or in the form of one or more corresponding electronic control units (ECUs).

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2014/0003616 A1 [0004, 0022]

Claims (13)

A method of operating a headset, in particular an in-ear headset, by a user together with a terminal, characterized in that the electrical resistance of at least one loudspeaker of the headset is determined (500-510) and detected on the basis of the determined resistance (520) whether the headset is located in or on the ear or outside or away from the user's ear. Method according to Claim 1 , characterized in that the electrical AC resistance of at least one speaker of the headphone is determined. Method according to Claim 1 or 2 characterized in that the electrical current flowing through at least one loudspeaker of the headset is detected as a function of time (500) that time-dependent resistance values are calculated based on a specifiable electrical drive voltage from the detected electrical current values (505) that the time-dependent resistance values Fourier transform into frequency dependent resistance values are converted (515), and it is detected (520) from the resulting frequency dependent resistance values whether the headset is located in or on the ear or outside or away from the user's ear. Method according to Claim 3 , characterized in that from the frequency-dependent resistance values, a frequency-dependent signature for the resistance profile is generated at in or on the ear and out of the ear headphones arranged, based on the recognition (520) is performed. Method according to Claim 4 , characterized in that by means of the frequency-dependent signature additionally one or more of the following conditions or quantities is recognized: - The headset type; - the user; the termination or pausing of the playback of an audio file by means of the terminal; - the detection of the termination of a call by means of a headset having handsfree or switching to a handsfree mode; - The supply of two channel contributions of a stereo audio signal to only one speaker. Method according to one of the preceding claims, characterized in that the recognition (520) whether the headphone is arranged in or on the ear or outside or away from the user's ear is trained. Method according to one of the preceding claims, characterized in that only relative changes in resistance are taken into account in the recognition (520). Computer program, which is set up, each step of a method according to one of Claims 1 to 7 perform. Machine-readable data carrier on which a computer program according to Claim 8 is stored. Electronic control device, which is set up, a headphone and / or a terminal by means of a method according to one of Claims 1 to 7 to control. Circuit arrangement for operating a headphone comprising at least one loudspeaker (205), in particular an in-ear headset, by a user together with a terminal, characterized by a load resistor (210) electrically connected to the at least one loudspeaker (205), a first amplifier for providing a bias voltage (212) such that a load voltage (215) is dropped across the load resistor (210), and an A / D converter (135, 230) for resistance sensing the at least one loudspeaker (205). Circuit arrangement according to Claim 11 , characterized in that supplied by two speakers (205, 235) voltage signals by means of a multiplexer (320) to the A / D converter (135) are supplied. Circuit arrangement according to Claim 11 or 12 , characterized in that by two speakers (205, 235) and supplied by a microphone voltage signals by means of a multiplexer (320) to the A / D converter (135) are supplied.

Images