阅读说明：本技术 用于测量动态扬声器驱动器的力因子的测量设备 (Measuring device for measuring the force factor of a dynamic loudspeaker driver ) 是由 R·弗里德里希 于 2019-09-16 设计创作，主要内容包括：一种用于测量动态扬声器驱动器的力因子的测量设备包括：第一端子和第二端子；放大器；电压测量装置；位移测量装置；以及电气/电子装置。该测量设备用于在第一操作模式下操作放大器以产生电压并且在第一操作模式期间操作电气/电子装置以具有低阻抗,使得该电压存在于第一端子处以使振膜相对于磁体移位；并在第二操作模式期间操作电气/电子装置以具有高阻抗,使得连接到测量设备的动态扬声器移动其移位的振膜,从而导致由动态扬声器驱动器产生并存在于第一端子处的感应电压。该测量设备包括评估装置,其被配置为响应于在第二操作模式期间所测量的振膜的位移以及由电压测量装置测量的感应电压来确定连接到测量设备的动态扬声器驱动器的力因子。(A measurement device for measuring a force factor of a dynamic loudspeaker driver comprising: a first terminal and a second terminal; an amplifier; a voltage measuring device; a displacement measuring device; and electrical/electronic devices. The measuring device is for operating the amplifier in a first mode of operation to generate a voltage and operating the electrical/electronic device to have a low impedance during the first mode of operation such that the voltage is present at the first terminal to displace the diaphragm relative to the magnet; and operating the electrical/electronic device to have a high impedance during a second mode of operation such that a dynamic loudspeaker connected to the measurement apparatus moves its displaced diaphragm, resulting in an induced voltage generated by the dynamic loudspeaker driver and present at the first terminal. The measuring device comprises evaluation means configured to determine a force factor of a dynamic loudspeaker driver connected to the measuring device in response to the displacement of the diaphragm measured during the second mode of operation and the induced voltage measured by the voltage measuring means.)

1. A measurement device for measuring a force factor of a dynamic loudspeaker driver, the measurement device comprising:

a first terminal and a second terminal for connecting a dynamic speaker driver to the measurement device, the dynamic speaker driver including a magnet, a diaphragm movably mounted relative to the magnet, and a voice coil attached to the diaphragm and operatively coupled with the magnet;

an amplifier configured to generate a voltage;

a voltage measurement device configured to measure a voltage present at the first terminal;

a displacement measuring device configured to measure a displacement of the diaphragm or the voice coil relative to the magnet;

an electrical/electronic device connected between the amplifier and the first terminal; the measurement device is configured to operate the amplifier in a first mode of operation to generate a voltage and to operate the electrical/electronic apparatus to have a low impedance during the first mode of operation such that the voltage generated by the amplifier is present at the first terminal to displace the diaphragm relative to the magnet, and the measurement device is configured to operate the electrical/electronic apparatus to have a high impedance during a second mode of operation such that the dynamic speaker driver connected to the measurement device moves the displaced diaphragm of the dynamic speaker driver resulting in an induced voltage generated by the dynamic speaker driver and present at the first terminal, the second mode of operation being immediately subsequent to the first mode of operation; and

an evaluation means configured to determine the force factor of the dynamic loudspeaker driver connected to the measuring device in response to the displacement of the diaphragm measured during the second mode of operation and the induced voltage measured by the voltage measuring means.

2. The measurement device according to claim 1, wherein the electrical/electronic arrangement comprises a first diode arrangement having a first anode, a first cathode and a first threshold voltage, the measurement device being configured to operate the amplifier to generate the voltage during the first mode of operation such that the voltage has a polarity allowing the first diode arrangement to be electrically conductive, and to operate the amplifier to be switched off or not to generate the voltage during the second mode of operation.

3. The measurement apparatus of claim 2, wherein the first threshold voltage of the first diode arrangement is greater than an absolute value of the induced voltage generated by the dynamic speaker driver connected to the measurement apparatus during the second mode of operation.

4. The measurement device of claim 2, wherein the measurement device comprises a second diode arrangement having a second anode, a second cathode and a second threshold voltage, the anode of one of the first and second diode arrangements being connected to the first terminal and the cathode of the other of the first and second diode arrangements being connected to the first terminal, the measurement device being configured to:

operating the amplifier during a third mode of operation to generate a voltage of opposite polarity compared to the polarity of the voltage during the first mode of operation to displace the diaphragm of the dynamic loudspeaker driver connected to the measurement device relative to its magnet, and

operating the amplifier during a fourth operating mode such that it is switched off or does not generate a voltage such that the dynamic loudspeaker driver connected to the measuring device can move its displaced diaphragm resulting in a further induced voltage generated by the dynamic loudspeaker driver and present at the first terminal, the evaluation means being configured to determine a force factor of the dynamic loudspeaker driver connected to the measuring device in response to the displacement of the diaphragm measured during the fourth operating mode and the further induced voltage measured by the measuring means, the fourth operating mode immediately following the third operating mode.

5. The measurement device of claim 4, wherein the second threshold voltage of the second diode arrangement is greater than an absolute value of the another induced voltage generated by the dynamic speaker driver connected to the measurement device during the fourth mode of operation.

6. A measurement device as claimed in claim 4, wherein the measurement device comprises a switch having a first switch state in which the first diode arrangement is connected to the amplifier and the second diode arrangement is not connected to the amplifier, and a second switch state in which the second diode arrangement is connected to the amplifier and the first diode arrangement is not connected to the amplifier, an anode of one of the first and second diode arrangements being connected to the first terminal, and a cathode of the other of the first and second diode arrangements being connected to the first terminal, the measurement device being configured to:

operating the switch in its first switching state during the first and second operating modes, and

operating the switch in its second switching state during the third and fourth modes of operation.

7. The measurement device according to claim 2, wherein the electrical/electronic apparatus is a further switch, the measurement device being configured to operate the further switch such that it is closed during the first mode of operation and such that it is open during the second mode of operation.

8. The measurement device of claim 1, wherein the measurement device comprises a third terminal for connecting a dynamic speaker driver to the measurement device, the dynamic speaker driver comprising: a magnet, a diaphragm movably mounted relative to the magnet, and first and second voice coils attached to the diaphragm and operatively coupled with the magnet and connected in series with each other;

the voltage measuring device is configured to measure at least one of a voltage present at the first terminal or a voltage present at the third terminal;

the dynamic loudspeaker driver connected to the measurement device moves its displaced diaphragm during the second mode of operation, resulting in a first induced voltage associated with the first voice coil and a second induced voltage associated with the second voice coil generated by the dynamic loudspeaker driver, the first induced voltage being present at the first terminal and the second induced voltage being present at the third terminal; and is

The evaluation means is configured to determine at least one of a force factor, a first force factor or a second force factor of the dynamic loudspeaker driver connected to the measuring device in response to the displacement of the diaphragm measured during a second mode of operation and at least one of the first induced voltage and the second induced voltage measured by the voltage measuring means, the force factor being associated with the first voice coil and the second voice coil, the first force factor being associated with the first voice coil and the second force factor being associated with the second voice coil.

9. The measurement device according to claim 1, wherein the measurement device comprises a control arrangement configured to control the operation of the measurement device.

10. The measurement device of claim 1, wherein the displacement of the diaphragm changes over time during the second mode of operation, the evaluation means is configured to determine the velocity of the diaphragm during the second mode of operation in response to the measured displacement with respect to time, and the evaluation means is configured to determine the force factor of the dynamic loudspeaker driver connected to the measurement device in response to the velocity of the diaphragm during the second mode of operation and in response to the induced voltage with respect to time measured by the voltage measurement means during the second mode of operation.

Technical Field

The invention relates to a measuring device for measuring a force factor of a dynamic loudspeaker driver.

Background

A dynamic speaker driver generally includes a magnet, a diaphragm movably mounted with respect to the magnet, and a voice coil attached to the diaphragm. The voice coil is operatively coupled with the magnet.

For example, a dynamic speaker driver may be described by a set of electromechanical parameters that describe its performance. One of the electromechanical parameters is the force factor. The force factor is a function of the displacement of the voice coil or diaphragm depending on the geometry of the voice coil and the magnetic field generated by the magnet.

Disclosure of Invention

It is an object of the invention to provide a device for measuring a force factor of a dynamic loudspeaker driver.

The object of the invention is achieved by a measuring device for measuring a force factor of a dynamic loudspeaker driver, comprising:

first and second terminals for connecting a dynamic speaker driver to a measurement device, the dynamic speaker driver including a magnet, a diaphragm movably mounted with respect to the magnet, and a voice coil attached to the diaphragm and operatively coupled with the magnet;

an amplifier configured to generate a voltage;

a voltage measurement device configured to measure a voltage present at the first terminal;

a displacement measuring device configured to measure a displacement of the diaphragm or the voice coil relative to the magnet;

an electric/electronic device connected between the amplifier and the first terminal; the measuring device is configured to operate the amplifier to generate a voltage in a first operating mode and to operate the electrical/electronic device to have a low impedance during the first operating mode such that the voltage generated by the amplifier is substantially present at the first terminal to displace the diaphragm relative to the magnet, and to operate the electrical/electronic device to have a high impedance during a second operating mode such that a dynamic speaker driver connected to the measuring device moves the displaced diaphragm of the dynamic speaker driver resulting in an induced voltage generated by the dynamic speaker driver and present at the first terminal, the second operating mode being immediately subsequent to the first operating mode; and

an evaluation means configured to determine a force factor of a dynamic loudspeaker driver connected to the measuring device in response to the displacement of the diaphragm measured during the second mode of operation and the induced voltage measured by the voltage measuring means.

The measuring device may comprise a control arrangement configured to control the measuring device. In particular, the control means controls the amplifier during different operating modes.

The measurement device includes an amplifier that generates a voltage during a first mode of operation. The voltage is preferably a direct voltage. The measuring device further comprises a first terminal and a second terminal at which a dynamic loudspeaker driver is connected for measuring a force factor of the dynamic loudspeaker driver. For example, the second terminal may be connected to ground.

The electrical/electronic means of the measuring device are connected between the amplifier and the first terminal. During the first mode of operation, the electrical/electronic device has a low impedance, in particular a low resistance, preferably a zero resistance. Thus, the voltage generated by the amplifier during the first mode of operation is present at the first terminal, causing the diaphragm and the voice coil to displace relative to the magnet. During the first mode of operation, the diaphragm and the voice coil are displaced according to the value of the voltage. The voltage present at the first terminal may be measured with respect to a reference potential, in particular with respect to ground.

During the second mode of operation, the electrical/electronic device has a high impedance, preferably a high resistance, even more preferably an "infinite" resistance. Depending on the type of electrical/electronic device, the measurement apparatus may be configured to operate the amplifier during the second mode of operation such that it is off or does not generate a voltage. This can be controlled by the control means (if applicable).

Thus, during the second mode of operation, the voltage of the amplifier is no longer present at the first terminal, and the diaphragm can be displaced or deflected back therefrom. Due to this movement, a voltage is induced in the voice coil. The induced voltage may be measured by a voltage measuring device.

The measuring device comprises evaluation means configured to determine a force factor of a dynamic loudspeaker driver connected to the measuring device in response to the displacement (excursion) of the diaphragm or voice coil measured during the second mode of operation and the induced voltage measured by the measuring means during the second mode of operation.

The force factor bl (z) is an electromechanical parameter of the dynamic loudspeaker driver and is a function of the voice coil or diaphragm displacement or excursion z, which depends on the geometry of the voice coil and the magnetic field generated by the magnet. The force factor also satisfies the following equation:

BL(z,t)*v(z,t)＝U_emf(t)

wherein, U_emfIs the induced voltage, and v (z) is the velocity of the diaphragm or voice coil moving during the second mode of operation. During the second mode of operation, the diaphragm (and hence the voice coil) moves, causing the displacement or excursion of the diaphragm to change with respect to time t.

The displacement or excursion of the diaphragm changes over time during the second mode of operation. The evaluation means may be configured to determine the velocity of the diaphragm or voice coil during the second mode of operation in response to the measured displacement with respect to time. The evaluation means may be configured to determine a force factor of the dynamic loudspeaker driver connected to the measuring device in response to the velocity of the diaphragm or voice coil during the second mode of operation and in response to the induced voltage with respect to time measured by the measuring means during the second mode of operation.

Such displacement or offset measuring devices are known to the skilled person and may for example comprise a laser.

The electrical/electronic device may comprise or may be a first diode arrangement. The first diode arrangement has a first anode, a first cathode and a first threshold voltage. The measuring device may then be configured to operate the amplifier during a first mode of operation to generate a voltage such that the voltage has a polarity that allows the first diode arrangement to be electrically conductive, and to operate the amplifier during a second mode of operation subsequent to the first mode of operation to turn it off or not generate a voltage.

The polarity of the voltage is selected such that the first diode arrangement is conducting during the first mode of operation. For example, if the first anode of the first diode arrangement is connected to the amplifier and the first cathode of the first diode arrangement is connected to the first terminal, the voltage is a positive voltage to allow a current to flow through the first diode arrangement, resulting in a low resistance, i.e. an on-state of the first diode arrangement.

When the voltage of the amplifier decreases to zero, the current stops flowing through the first diode arrangement and is also prevented from flowing through the first diode arrangement due to the induced voltage during the second mode of operation.

The first diode arrangement has a threshold voltage, which may also be referred to as built-in potential or knee voltage, as known to the person skilled in the art. Silicone diodes typically have a threshold or knee voltage of about 0.7V.

The first diode arrangement may be a single first diode, in particular a single first semiconductor or a p-n junction diode. The first diode arrangement may be a plurality of first diodes connected in series, in particular a plurality of first semiconductor or p-n junction diodes connected in series. The threshold voltage of a diode arrangement comprising a plurality of semiconductor diodes connected in series is greater than the threshold voltage of a single semiconductor diode.

The first diode arrangement is preferably selected such that the first threshold voltage is larger than the absolute value of the induced voltage generated by the dynamic loudspeaker driver connected to the measurement device during the second mode of operation, thereby ensuring that the first diode arrangement has a high impedance, in particular a high resistance, during the second mode of operation.

The measurement device may comprise a second diode arrangement having a second anode, a second cathode and a second threshold voltage. An anode of one of the first and second diode arrangements is connected to the first terminal and a cathode of the other diode arrangement is connected to the first terminal. The measurement device may then be configured to:

operating the amplifier during a third mode of operation to generate a voltage of opposite polarity compared to the polarity of the voltage during the first mode of operation to displace a diaphragm of a dynamic loudspeaker driver connected to the measuring device relative to a magnet of the dynamic loudspeaker driver, and

the amplifier is operated during a fourth mode of operation such that it is switched off or does not generate a voltage, such that a dynamic loudspeaker driver connected to the measuring device can move a displaced diaphragm of the dynamic loudspeaker driver, resulting in a further induced voltage generated by the dynamic loudspeaker driver and present at the first terminal, the fourth mode of operation immediately following the third mode of operation.

The evaluation means may then be configured to determine a force factor of a dynamic loudspeaker driver connected to the measuring device in response to the displacement of the diaphragm measured during the fourth mode of operation and the further induced voltage measured by the measuring means.

The second diode arrangement may be a single second diode, in particular a single second semiconductor or a p-n junction diode. The second diode arrangement may be a plurality of second diodes connected in series, in particular a plurality of second semiconductor or p-n junction diodes connected in series.

The second diode arrangement is preferably selected such that the second threshold voltage is larger than the absolute value of the induced voltage generated by the dynamic loudspeaker driver connected to the measurement device during the fourth mode of operation, thereby ensuring that the second diode arrangement has a high impedance, in particular a high resistance, during the fourth mode of operation.

For example, if the cathode of the first diode arrangement is connected to the first terminal, the voltage during the first mode of operation is a positive voltage. Then, the anode of the second diode arrangement is connected to this terminal and the voltage during the third mode of operation is a negative voltage.

The measuring device may comprise a switch, preferably a semiconductor switch, such as a FET. The switch has a first switching state in which the first diode arrangement is connected to the amplifier and the second diode arrangement is not connected to the amplifier, and a second switching state in which the second diode arrangement is connected to the amplifier and the first diode arrangement is not connected to the amplifier. The measuring device may then be configured to operate the switch in its first switching state during the first and second operation modes and to operate the switch in its second switching state during the third and fourth operation modes.

The electrical/electronic device may be another switch. The measurement apparatus may then be configured (e.g. controlled by the control means) to operate the further switch so that it is closed during the first mode of operation and to operate the further switch so that it is open during the second mode of operation. Thus, the amplifier is substantially directly connected to the first terminal during the first mode of operation and disconnected during the second mode of operation. The further switch is preferably a semiconductor switch, such as a transistor, in particular a FET.

The dynamic speaker driver may include a single voice coil or two voice coils or more than two voice coils connected in series. A dynamic speaker driver having at least two voice coils is associated with more than one force factor. One of the force factors is associated with two voice coils or all voice coils connected in series. Additionally, each voice coil may be associated with its respective force factor.

The voice coil may be implemented as a laminated voice coil arrangement, where, for example, two identical voice coils, each half weight, are attached or glued together to geometrically and electrically form a single voice coil. For example, two voice coils are connected at the midpoint.

The measuring device may comprise a third terminal or terminals for connecting the dynamic loudspeaker driver to the measuring device, wherein the dynamic loudspeaker driver comprises two voice coils or more than two voice coils, i.e. a first voice coil and a second voice coil attached to the diaphragm and operatively coupled with the magnet and connected in series. The dynamic loudspeaker driver is then connected to the first, second and third terminals of the measuring device.

The voltage measuring device may then be configured to measure at least one voltage present at the first terminal or at the third terminal.

During a second mode of operation, a dynamic loudspeaker having at least two voice coils connected in series and connected to a measurement device moves a displaced diaphragm of the dynamic loudspeaker resulting in a first induced voltage associated with a first voice coil and a second induced voltage associated with a second voice coil generated by a dynamic loudspeaker driver. The first induced voltage is present at the first terminal and the second induced voltage is present at the third terminal.

The evaluation means may then be configured to determine at least one of a force factor of a dynamic loudspeaker driver connected to the measuring device, a first force factor or a second force factor in response to the displacement of the diaphragm measured during the second mode of operation and at least one of the first induced voltage and the second induced voltage measured by the voltage measuring means. A force factor is associated with the first and second voice coils being connected in series, the first force factor being associated with the first voice coil, and the second force factor being associated with the second voice coil. The force factor bl (z) of two voice coils connected in series can be determined according to the formula mentioned before:

BL(z,t)*v(z,t)＝U_emf(t)

wherein, U_emfIs the induced voltage.

Force factor BL of nth voice coil (i.e., first (n-1) or second (n-2))_n(z) can be determined according to the following formula:

BL_n(z,t)*v(z,t)＝U_emf,n(t)

wherein, U_emf,nIs the induced voltage at the respective terminal and is associated with the nth voice coil.

Drawings

Fig. 1 is a measuring device for measuring a force factor of a dynamic loudspeaker driver;

fig. 2 and 3 are diagrams illustrating measurements of a dynamic loudspeaker driver with a measuring device;

FIG. 4 is an alternative embodiment of a measuring device;

FIG. 5 is another measuring device;

FIG. 6 is a circuit showing a measurement of a dynamic loudspeaker driver having two voice coils;

FIG. 7 is a graph illustrating the force factor of a dynamic speaker driver having two voice coils; and

fig. 8 is a circuit showing an example of excitation of a dynamic speaker driver having two voice coils.

Detailed Description

Fig. 1 shows a measuring device 1 for measuring a force factor bl (z) of a dynamic loudspeaker driver 20.

Dynamic speaker driver 20 includes a magnet 21, a diaphragm 22 movably mounted with respect to magnet 21, and a voice coil 23 attached to diaphragm 22 and operatively coupled with magnet 21. In operation, the voice coil 23 moves with the diaphragm relative to arrow 24.

The measuring device 1 comprises a first terminal 2 and a second terminal 3 (the second terminal 3 being connectable to ground 4). When measuring the force factor bl (z) of the dynamic loudspeaker driver 20, the dynamic loudspeaker driver 20 is connected to the first terminal 2 and the second terminal 3.

The measuring apparatus 1 includes: an amplifier 5, the amplifier 5 being configured to generate, in particular, a direct voltage U_dcVoltage of (d); and a voltage measuring device 6, the voltage measuring device 6 being configured to measure a voltage u present at the first terminal 2. In particular, the voltage measuring device 6 is configured to measure the voltage u across the first terminal 2 and the second terminal 3, i.e. the voltage u at the first terminal 2 with respect to ground 4.

The measuring device 1 comprises a displacement measuring means 7, which displacement measuring means 7 is configured to measure a displacement or deflection z of the diaphragm 22 relative to the magnet 21. The displacement measuring device 7 comprises, for example, a laser.

The measuring device 1 comprises an evaluation means 8, which evaluation means 8 is configured to determine a force factor bl (z) of a dynamic loudspeaker driver 20 connected to the measuring device 1.

The measuring device 1 may comprise a control means 9, which control means 9 is configured to control the operation of the measuring device 1, in particular the amplifier 5.

The measuring device 1 comprises an electrical/electronic device 10 connected between the amplifier 5 and the first terminal 2.

Fig. 2 and 3 are graphs illustrating the measurement of the force factor bl (z).

The measuring device 1 is configured to operate in a first operating modeDuring this first mode of operation, the amplifier 5, controlled by the control means 9, generates a direct voltage U_dc. During the first mode of operation, the electrical/electronic device 10 has a low impedance, preferably a low resistance or even no resistance at all (i.e. is conducting). Thus, the DC voltage U generated by the amplifier 5_dcIs present substantially at the first terminal 2 and displaces the diaphragm 22 relative to the magnet 21. During the first mode of operation, the voltage U across the first terminal 2 and the second terminal 3 (i.e. the voltage U at the first terminal 2 with respect to ground 4) is substantially equal to the direct voltage U_dc. For the example shown in fig. 2 and 3, the first mode of operation lasts from t 0.5ms to t 1 ms. The resulting displacement or excursion z of the diaphragm 22 is shown in FIG. 2.

The measuring device 1 is configured to operate in a second operating mode immediately following the first operating mode. In the examples shown in fig. 2 and 3, the second mode of operation starts at t ═ 1 ms.

During the second mode of operation, the electrical/electronic device 10 has a high impedance, so that a dynamic loudspeaker driver 20 connected to the measuring apparatus 1 moves a displaced diaphragm 22 of the dynamic loudspeaker driver 20, resulting in an induced voltage U generated by the dynamic loudspeaker driver 20_emf. The induced voltage U_emfIs present at the first terminal 2. During the second mode of operation, the voltage U across the first terminal 2 and the second terminal 3 (i.e. the voltage U at the first terminal 2 with respect to ground 4) is substantially equal to the induced voltage U measured by the voltage measuring device 6_emf。

The evaluation means 8 is configured to be responsive to the induced voltage U measured by the voltage measurement means 6 during the second mode of operation_emfAnd the measured displacement or deflection z of the diaphragm 22 to determine the force factor bl (z) of the dynamic loudspeaker driver 20 connected to the measuring device 1.

The force factor BL (z) also satisfies the following equation:

BL(z,t)*v(z,t)＝U_emf(t)

where v is the velocity of the diaphragm 22 moving during the second mode of operation. During the second mode of operation, the diaphragm 22 (and hence the voice coil 23) moves, causing the displacement or excursion z of the diaphragm 22 to change with respect to time t. The velocity v may be derived by a varying displacement or offset z.

For the present embodiment, the evaluation device 8 is configured to determine the velocity v of the moving diaphragm 22 from the measured displacement or excursion z. The evaluation means 8 are configured to respond to the measured velocity v of the moving diaphragm 22 and to respond to the measured induced voltage U_emfTo determine the force factor bl (z).

For values where the determined velocity v is around zero, the displacement factor cannot be determined.

As shown in fig. 1, the electrical/electronic device 10 may comprise a first diode arrangement 11 or may be a first diode arrangement 11. The first diode arrangement 11 has a first anode a1, a first cathode C1 and a first threshold voltage U_{Threshold value}. Then, the measurement device 1 may be configured to operate the amplifier 5 during the first operation mode to generate the direct voltage U_dcSo that the DC voltage U is_dcHaving a polarity allowing the first diode arrangement 11 to be electrically conductive and operating the amplifier 5 during the second mode of operation such that it is switched off or does not generate a voltage. For example, if the DC voltage U_dcPositive, the first cathode C1 is connected to the first terminal 2, as shown in fig. 1.

When the voltage of the amplifier 5 decreases to zero at t-1 ms, then the second operation mode starts, the current stops flowing through the first diode arrangement 11 and the current is also prevented from being induced by the induced voltage U during the second operation mode_emfBut flows through the first diode arrangement.

The first diode arrangement 11 may be a single first diode, in particular a single first semiconductor or a p-n junction diode. The first diode arrangement 11 may be a plurality of first diodes connected in series, in particular a plurality of first semiconductor or p-n junction diodes connected in series.

The first diode arrangement 11 is preferably selected such that the first threshold voltage U is_{Threshold value}Greater than the induced voltage U generated by the dynamic loudspeaker driver 20 connected to the measuring device 1 during the second mode of operation_emfAbsolute value of (a).

The measurement device 1 may comprise a switch 13, preferably a semiconductor switch, e.g. a FET, and a second diode arrangement 12 having a second anode a2, a second cathode C2, and a second threshold voltage. The switch 13 has a first switching state in which the first diode arrangement 11 is connected to the amplifier 5 and the second diode arrangement 12 is not connected to the amplifier 5, and a second switching state in which the second diode arrangement 12 is connected to the amplifier 5 and the first diode arrangement 11 is not connected to the amplifier 5. The anode of one of the first diode arrangement 11 and the second diode arrangement 12 is connected to the first terminal 2, and the cathode of the other diode arrangement is connected to the first terminal. For the embodiment shown in fig. 1, the second anode a2 of the second diode arrangement 12 is connected to the first terminal 2.

For this embodiment, the measuring device 1 is configured (under control of the control means 9) to operate the switch 13 in its first switching state during the first and second operating modes and to operate the switch 13 in its second switching state during the third and fourth operating modes.

During the third operating mode, the amplifier 5 generates a dc voltage of opposite polarity compared to the polarity of the dc voltage during the first operating mode in order to displace the diaphragm 22 of the dynamic loudspeaker driver 20 connected to the measuring device 1 relative to the magnet 21 of the dynamic loudspeaker driver 20.

The fourth mode of operation is subsequent to the third mode of operation. During the fourth mode of operation, the amplifier 5 is switched off or generates no voltage. Then, the dynamic loudspeaker driver 20 connected to the measuring device 1 may move the displaced diaphragm 22 of the dynamic loudspeaker driver 20, resulting in a further induced voltage generated by the dynamic loudspeaker driver 20 and present at the first terminal 2.

The evaluation means 8 are then configured to determine the force factor of the dynamic loudspeaker driver 20 connected to the measuring device 1 in response to the displacement of the diaphragm 22 measured during the fourth operating mode and the further induced voltage measured by the voltage measuring means 6.

The second diode arrangement 12 may be a single second diode, in particular a single second semiconductor or a p-n junction diode. The second diode arrangement 12 may be a plurality of second diodes connected in series, in particular a plurality of second semiconductor or p-n junction diodes connected in series.

The switch 13 may be omitted if the absolute value of the voltage caused by the transducer speed is below the threshold voltage of the diode arrangements 11 and 12. This means that two diode arrangements are connected to the amplifier and to the terminals. In this case, the diode arrangement in the non-conducting state due to the signal polarity of the amplifier 5 only adds a very high impedance to the speaker-amplifier connection dominated by the conducting diode arrangement.

For example, if the amplifier 5 is configured to supply a positive direct voltage, the diode arrangement 11 will be in a conducting state and the diode arrangement 12 will be in a non-conducting state for both modes of operation.

The effect of such a high impedance connected in parallel to a low impedance connection can be rated low and therefore negligible if the measurement time and setup complexity can be reduced.

In an alternative embodiment shown in fig. 4, the electrical/electronic device 10 is another switch 14. The measuring device 1 is configured (controlled by the control means 9) to operate the further switch 14 such that it is closed during the first mode of operation and to operate the further switch 14 such that it is open during the second mode of operation. The further switch 14 is preferably a semiconductor switch, such as a transistor, in particular a FET.

Fig. 5 shows another measuring device 41 for measuring the force factor of a dynamic loudspeaker driver 51. The measuring device 41 of fig. 5 differs from the measuring devices of fig. 1, 4 in that it has a third terminal 42 in addition to the first terminal 2 and the second terminal 3. The measuring device 41 of fig. 5 is intended to measure, among other things, one or more force factors of a dynamic loudspeaker driver 50 having a first voice coil 53 and a second voice coil 54 connected in series. Fig. 6 shows a circuit diagram of the dynamic speaker driver 50.

Two voice coils 53, 54 are connected in series at a mid-point connection 55.

The dynamic speaker driver 50 has more than one force factor. In particular, the dynamic speaker driver 50 may have a force factor associated with both the first voice coil 53 and the second voice coil 54 connected in series, a first force factor associated with the first voice coil 53, and a second force factor associated with the second voice coil 54.

For the embodiment shown in fig. 5, 6, the first voice coil 53 is connected to the first terminal 2 and the third terminal 42, and the second voice coil 54 is connected to the third terminal 42 and the second terminal 3. The midpoint connection 55 is connected to the third terminal 42.

During the first mode of operation, the amplifier 5, controlled by the control means 9, generates a direct voltage U_dc. The voltage U across the first terminal 2 and the second terminal 3 is then equal to the direct voltage U_dc。

During the second mode of operation, the electrical/electronic device 10 has a high impedance, such that a dynamic loudspeaker driver 50 connected to the measurement apparatus 41 moves the displaced diaphragm 22 of the dynamic loudspeaker driver 50, resulting in a first induced voltage U generated by the first voice coil 53_emf,1And a second induced voltage U generated by a second voice coil 54_emf,2. Thus, the voltage u across the first voice coil 53₁Equal to the first induced voltage U_emf,1Voltage u across the second voice coil 54₂Equal to the second induced voltage U_emf,2. The induced voltage is measured (in particular simultaneously) by the voltage measuring device 6 of the measuring device 41. For example, the voltage measuring device 6 is configured to measure a voltage u across the first and second terminals 2, 3 and a voltage across the third and second terminals 42, 3. The voltage measuring device 6 or the evaluation device 8 is then configured to determine the first induced voltage U using the measured voltage_emf,1And a second induced voltage U_emf,2。

The force factor bl (z) of the two voice coils 53, 54 connected in series can be determined according to the formula mentioned before:

BL(z,t)*v(z,t)＝U_emf(t)

wherein, U_emfIs the induced voltage, i.e. the voltage u measured during the second mode of operation.

Force factor BL of first voice coil 53₁(z) can be determined according to the following formula:

BL₁(z,t)*v(z,t)＝U_emf,1(t)

force factor BL of second voice coil 54₂(z) can be determined according to the following formula:

BL2(z,t)*v(z,t)＝U_emf,2(t)

fig. 7 shows a diagram of the course of the force factor with respect to the displacement z.

Fig. 8 shows an alternative connection of the dynamic loudspeaker driver 50 with a measuring device 41 for measuring the force factor of the dynamic loudspeaker driver 50. In the example shown in fig. 8, the second voice coil 54 is connected to the first terminal 2 and the second terminal 3. Thus, during the first mode of operation, the diaphragm 22 is moved (i.e., displaced) only by the second voice coil 54. The first voice coil 53 is connected to the first terminal 2 and the third terminal 42.

During the second operation mode, the first induced voltage U can be determined_emf,1And a second induced voltage U_emf,2Corresponding voltage u₁、u₂And thus the corresponding force factor.

While modifications and changes may be suggested by those skilled in the art, it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art.