SPEAKERS WITH PASSIVELY CONTROLLED VOYAGE COIL SECTIONS

Abstract

The invention relates to a method for controlling a voice coil of a loudspeaker, comprising the steps of providing a magnetic circuit with an air gap, providing a voice coil suspended in the air gap, and applying an audio signal to the voice coil to move the voice coil along an axis of motion. The voice coil comprises a middle voice coil section, an upper voice coil section, and a lower voice coil section, arranged on the respective sides of the middle voice coil section. A middle control signal is supplied to the middle voice coil, and an upper rectified control signal, which attenuates a first current direction, and a lower rectified control signal, which attenuates a second current direction, are supplied to the upper and lower voice coil sections, respectively.The invention further relates to a voice coil control system and a loudspeaker with a voice coil control system.

Description

Field of invention

[0001] The present invention relates to a loudspeaker and in particular a voice coil arranged in such a way as to improve the power handling capacity and reduce the energy consumption of the control electronics. Background of the invention

[0002] With reference to Fig. Figures 1a-1b illustrate a voice coil drive system for a loudspeaker. The voice coil drive system is equipped with a voice coil 1 comprising a multitude of coil windings. These windings are driven by a control signal 40, causing the voice coil 1 to move the diaphragm 7 back and forth, thus generating an acoustic sound signal.

[0003] The coil windings are partially located within an air gap 3 of a magnetic circuit 2, with the highest magnetic flux density within the air gap 3. When the coil windings are energized, they interact with the magnetic field of the magnetic circuit 2 to generate an electromotive force that moves the voice coil 1. However, only the windings of the voice coil 1 that are substantially located within the air gap 3 provide a substantial force to move the voice coil 1 back and forth. The windings of the voice coil outside the air gap 3, which do not contribute a substantial electromotive force, are also energized simultaneously and thus contribute to the heating of the voice coil, which is a significant limiting factor in loudspeaker design.

[0004] JP S59 - 12 693 A concerns a loudspeaker, in particular a bass loudspeaker with good playback efficiency.

[0005] JP 2009 - 89 260 A refers to a loudspeaker with reduced loss during operation.

[0006] US 2009 / 0 028 371 A1 refers to loudspeaker design and loudspeaker drivers that produce more sound and less distortion and generate less heat. Summary of the invention

[0007] The inventors have identified the aforementioned problems and challenges related to the power consumption of loudspeakers and subsequently made the invention described below, which can reduce the power consumption of the voice coil and avoid unnecessary heating of the voice coil.

[0008] One aspect of the invention relates to a method for controlling a voice coil of a loudspeaker according to claim 1.

[0009] A voice coil can be understood as a coil of wire that, under the influence of a magnetic field, can generate an electromotive force to move a loudspeaker diaphragm and thus produce acoustic sounds. The magnetic field can be generated by a magnet, such as a permanent magnet or an electromagnet, within a magnetic circuit. This circuit may include an air gap in which the voice coil moves back and forth, thereby causing the loudspeaker diaphragm to move and produce acoustic sounds.

[0010] When an audio signal is applied, a current in the form of control signals, e.g. a central control signal and an auxiliary control signal, is supplied to the voice coil windings, which, due to the magnetic field, leads to an electromotive force on the coil windings that drives the voice coil along an axis of movement that can be essentially perpendicular to the coil windings.

[0011] A control signal applied to a voice coil typically includes current flowing alternately through the voice coil windings in a first current direction and a second current direction, the first and second current directions being opposite directions. When current flows through the voice coil windings in a first current direction, an electromotive force can be generated on the voice coil in a first direction along the axis of motion, and when current flows through the voice coil windings in a second current direction, an electromotive force can be generated on the voice coil in a second direction along the axis of motion, with the first and second directions being opposite directions along the axis of motion.Therefore, forces can be exerted on the voice coil in both directions of movement along the axis of movement, and this allows the voice coil to move back and forth within the air gap.

[0012] An audio signal is typically a type of electronic signal. In various forms, it can be an analog signal, continuous or pulsed. In various forms, it can also be a digital signal. When referring to the amplitude of an audio signal, this can refer to the amplitude of an analog audio signal or the audio signal level of a digital audio signal.

[0013] Typically, the reciprocating excursion, or displacement, of a voice coil in a loudspeaker is intended to reproduce the audio signal delivered to the loudspeaker by moving the loudspeaker diaphragm back and forth. Thus, an increasing amplitude of the audio signal within the loudspeaker's boundaries results in an increase in excursion. The audio signal can be provided by an external unit, such as an audio source configured to output an electrical audio signal, and equipped with means of transmitting that signal to the loudspeaker. Examples of such means include wired connections, such as a cabled electrical or optical connection, and wireless connections, such as a Bluetooth connection (e.g., Bluetooth A2DP or Bluetooth aptX) or a Wi-Fi connection.

[0014] According to various embodiments of the invention, the voice coil comprises several voice coil sections, e.g., it comprises an upper voice coil section, a middle voice coil section, and a lower voice coil section; however, the invention is not limited to only three sections, and further voice coil sections of the voice coil can be considered in other embodiments of the invention.

[0015] In various embodiments, voice coil sections can have the same or different heights, numbers of turns, and winding densities, and can include windings made of the same or different materials. The winding material of the voice coil sections can be selected from a list consisting of alloys, aluminum, silver, copper, or gold, or any combination thereof.

[0016] In various embodiments, each of these voice coil sections has a height of one-third of the voice coil height. However, the voice coil sections are not limited to having the same height or the same number of windings, etc. In the present disclosure, the "height" of a voice coil refers to the extent of the voice coil along the axis of motion.

[0017] For the control of the voice coil according to the invention, a central control signal based on the audio signal is supplied to a central voice coil section, and an auxiliary control signal, also based on the audio signal, is supplied to an upper voice coil section and a lower voice coil section. The supply of the auxiliary control signal comprises supplying an upper rectified control signal to the upper voice coil section and supplying a lower rectified control signal to the lower voice coil section. The upper rectified control signal can be generated by attenuating or blocking a first current direction of the auxiliary control signal, while the lower rectified control signal can be generated by attenuating or blocking a second current direction of the auxiliary control signal, which is opposite to the first current direction.

[0018] The main control signal and the auxiliary control signal can be the same control signal or different control signals in various embodiments. "Different" can be understood to mean that the auxiliary control signal is a representation of the main control signal, characterized in that it has a lower amplitude than the main control signal, i.e., a lower gain compared to the main control signal.

[0019] Attenuation of a current can be understood as a reduction of the current and / or voltage of the signal. For example, an upper rectified control signal can be generated by attenuating a first current direction of an auxiliary control signal. Therefore, the magnitude of the current flow in a first current direction in the upper rectified control signal can be smaller than the magnitude of the current flow in a first current direction in the auxiliary control signal. The attenuation preferably represents a reduction of the current and / or voltage by at least 50%, such as at least 75%, at least 90%, or preferably at least 99%.

[0020] Blocking a current can be understood as a reduction of the current, so that after the current is blocked, no substantial current flows.

[0021] According to the invention, the attenuation or blocking of the auxiliary signal is achieved by passive rectification, i.e., attenuation or blocking of one current direction by passive means, i.e., without the need for active control. Therefore, for passive rectification, no regulating signal or current source is required other than a control signal. Passive rectification can be achieved, for example, by diodes or other inactive components or circuits thereof. In various embodiments of the invention, the upper rectified control signal is generated by passing the auxiliary control signal through a rectifier unit, e.g., a diode. A passive rectifier unit or a rectifier unit can be understood as a unit, device, circuit, or circuit element that processes current asymmetrically, i.e.,A rectifier unit can react in a first way to a current in a first direction and in a second way to a current in a second direction.

[0022] In various embodiments, when the voice coil is not driven (i.e., at rest in equilibrium without an applied signal), the middle voice coil section can be located substantially within the air gap, the upper voice coil section can be located substantially outside the air gap, and the lower voice coil section can be located substantially outside the air gap. If a control signal is applied to a voice coil section while it is substantially within the air gap, the resulting electromotive force can be greater compared to an electromotive force produced by applying the same control signal to the same voice coil section when it is substantially outside the air gap.

[0023] When the voice coil is driven and thus moves along its axis of motion, the voice coil sections can move in and out of the air gap depending on their direction, amplitude of displacement, and geometry. The contribution to generating the electromotive force can therefore vary from different voice coil sections as the voice coil moves back and forth.

[0024] For small audio signals, e.g., with low amplitude, which can lead to small voice coil excursions, the invention allows primarily a central voice coil section capable of generating an electromotive force. For a larger audio signal, e.g., with a larger amplitude, a contribution from the upper and / or lower voice coil section may be required to generate an electromotive force in order to reproduce the audio signal.

[0025] According to the invention, the current supplied to the voice coil sections of the segmented voice coil can be reduced by damping or blocking control signals. It is particularly advantageous to block the current to the voice coil sections that do not contribute to generating an electromotive force. In various embodiments, this can be achieved by using one or more rectifier units, e.g., diodes. This allows the displacement to reproduce an audio signal, while the power consumption and excessive heating of a loudspeaker can be significantly reduced according to the invention.

[0026] In various embodiments, rectifier units or diodes can additionally block the auxiliary control signal below a certain threshold amplitude and / or a certain threshold current. This can further reduce power consumption and heat generation when only small deflections are required for audio signal reproduction.

[0027] In various embodiments, the upper rectified control signal is provided by a first half-wave rectification of the auxiliary control signal, and the lower rectified control signal is provided by a second half-wave rectification of the auxiliary control signal, wherein the first half-wave rectification blocks a first current direction and the second half-wave rectification blocks a second current direction.

[0028] In contrast to, for example, an AC-DC converter or a full-wave bridge rectifier, the rectification according to the invention is not intended to move the entire signal or energy content into the positive or negative range, but rather to actually exclude the entire negative content of, for example, the lower rectified control signal and the entire positive content of, for example, the upper rectified control signal, and to transmit the remaining content as unchanged as possible. This is because the upper and lower voice coil sections driven by these signals, and because the voice coil geometry according to the invention, depending on its geometric configuration, effectively operate only with either the positive or the negative signal content.

[0029] In various embodiments, a rectifier unit with a specific threshold current and / or voltage is integrated. An auxiliary control signal whose current and / or voltage is less than the threshold current and / or voltage is attenuated or blocked by the rectifier unit. For a small audio signal, e.g., one with low amplitude, sufficient excursion can be generated by the middle voice coil section and may not require electromotive force generated by the upper and / or lower voice coil sections to reproduce the audio signal. In this scenario, one rectifier unit can block or attenuate the current to the upper voice coil section, and another rectifier unit can block or attenuate the current to the lower voice coil section, i.e., block both current directions in both rectifier units.If an audio signal has a sufficiently large amplitude that it might not be accurately reproduced by the excursion generated by a middle voice coil section alone, the current of the auxiliary control signal can be greater than the threshold current and / or threshold voltage of the rectifier unit. This allows the upper and lower voice coil sections to contribute to generating an electromotive force, enabling the excursion to reproduce the audio signal within the limits of the voice coil.

[0030] Thus, with small audio signals, e.g. with low amplitude, no significant current is supplied to the upper or lower voice coil section, which, according to the invention, can reduce power consumption and excessive heating compared to a prior art voice coil system.

[0031] In practice, a rectifier unit can be a diode, which may be characterized by an asymmetrical conductance, i.e., low resistance for one current direction and high resistance for the opposite current direction within the current and / or voltage limits of the diode.

[0032] According to one embodiment of the invention, neither the upper rectifier unit nor the lower rectifier unit contains a full-wave rectifier circuit or a full-wave bridge rectifier.

[0033] As explained above, the rectifier unit according to the present invention should not mirror the negative signal content to the positive side of the signal and vice versa. Therefore, the rectifier unit should, for example, not contain a diode bridge for full-wave rectification.

[0034] Therefore, with small audio signals, e.g. with low amplitude, no substantial current is supplied to the upper or lower voice coil section, which, according to the invention, can reduce power consumption and excessive heating compared to a prior art voice coil system.

[0035] This behavior allows a diode to be used as a rectifier unit according to the invention.

[0036] In embodiments where diodes are used to achieve rectification, and where the forward voltage drop is undesirable, the forward voltage drop can be compensated. Compensation can, for example, involve forward-biasing the diodes with a DC voltage slightly lower than the intrinsic forward voltage drop of the diodes, e.g., a DC voltage of 0.6 V for silicon diodes with a turn-on voltage of 0.7 V, or 0.25 V for germanium or Schottky diodes with a turn-on voltage of 0.30 V. Alternatively, the auxiliary control signal can be adjusted by similar amounts to compensate for the forward voltage drop.

[0037] The individual voice coil sections of a segmented voice coil can have different geometries, e.g., different numbers of windings, winding densities, voice coil section heights, etc. Therefore, it can be advantageous for the auxiliary control signal to have a signal amplitude that differs from the amplitude of the main control signal. In various embodiments, the relative amplitudes can be selected to ensure a linear response of the voice coil to an applied audio signal.

[0038] The individual voice coil sections of a segmented voice coil can have identical geometries, e.g., the same number of windings, winding densities, voice coil section heights, etc. Therefore, it can be advantageous for the auxiliary control signal to have a signal amplitude equal to the amplitude of the main control signal. In various embodiments, the amplitudes can be selected to ensure a linear response of the voice coil to an applied audio signal.

[0039] In various embodiments, the rectifier units do not need to be the same; for example, a first type of rectifier unit is responsible for providing the first upper rectified control signal and the first lower rectified control signal, while a second type of rectifier unit is responsible for providing the second upper rectified control signal and the second lower rectified control signal.

[0040] The prior art in the field of loudspeakers includes both voice coils whose height is greater than the height of the air gap along the axis of motion and voice coils whose height is less than the height of the air gap along the axis of motion. In this disclosure, the height of the air gap refers to the extent of the air gap along the axis of motion and not to the narrow distance between the magnet or pole pieces that form the air gap. A voice coil whose height is greater than the height of the air gap along the axis of motion can be referred to as an over-constrained coil, while a voice coil whose height is less than the height of the air gap along the axis of motion can be referred to as an under-constrained coil. The design and geometry can preferably be based on the intended application of the voice coil system.

[0041] The present invention is applicable in embodiments in which the height of the individual voice coil sections is smaller than the height of the air gap along the axis of motion, and also in embodiments in which the height of the individual voice coil sections is larger than the height of the air gap along the axis of motion.

[0042] The invention can also be applied in embodiments in which the overall height of the individual voice coil sections is smaller than the height of the air gap along the axis of movement, and also in embodiments in which the overall height of the individual voice coil sections is greater than the height of the air gap along the axis of movement.

[0043] Furthermore, the invention is applicable in embodiments in which the height of the individual voice coil sections has the same height as the air gap along the axis of movement, and also in embodiments in which the total height of the individual voice coil sections has the same height as the air gap along the axis of movement.

[0044] Furthermore, the invention is applicable in embodiments in which the height of the voice coil sections is individually smaller, larger and / or the same as the height of the air gap along the axis of movement.

[0045] One aspect of the invention relates to a voice coil control system of a loudspeaker according to claim 13.

[0046] The method for controlling a voice coil can be used according to the invention in a voice coil control system of a loudspeaker. As such, the integrated rectifier units can ensure that a reduced amount of current is supplied to selected voice coil sections when these sections are not able to contribute to generating a substantial electromotive force.

[0047] In voice coil systems known from the prior art, the entire voice coil is often supplied with current, even though significant sections of the voice coil do not contribute to generating an electromotive force. This can be considered a waste of energy and can lead to heat generation, which limits the performance of a voice coil system. This invention ensures that the heat generation and power consumption of voice coil sections that cannot contribute to generating an electromotive force are significantly reduced.

[0048] A voice coil drive system as described herein can offer all the advantages and benefits described above in relation to the method for driving a voice coil. Thus, a loudspeaker according to the present invention can offer the advantageous effect of low power consumption and a reduction in excessive heating within the loudspeaker due to the efficiency of the segmented voice coil. Drawings

[0049] Various embodiments of the invention are described below with reference to the drawings, wherein Fig. 1a-1b shows a conventional loudspeaker known according to the state of the art, Fig. 2 represents a loudspeaker with a voice coil drive system comprising a middle voice coil section, an upper voice coil section and a lower voice coil section according to an embodiment of the invention, Fig. Figures 3a-3c illustrate the reciprocating translation of the voice coil according to embodiments of the invention, comprising three voice coil sections. Fig. Figures 4a-4b illustrate different configurations for providing an intermediate control signal and an auxiliary control signal for the multiple voice coil sections according to the embodiments of the invention. Fig. 5 represents a loudspeaker according to an embodiment of the invention, Fig. Figures 6a-6c illustrate different configurations for applying a mean control signal and an auxiliary control signal to the plurality of voice coil sections according to the invention. Fig. Figures 7a-7b illustrate configurations of the voice coil sections according to different embodiments of the invention, and Fig. Figure 8 illustrates a preferred processing of the control signal according to various embodiments of the invention. Detailed description

[0050] Fig. Figure 1a shows a sectional view of a state-of-the-art loudspeaker. Fig. Figure 1b shows a section view along line 1b-1b in Fig. 1a. The loudspeaker contains two concentrically aligned magnetic elements 2, which form a magnetic circuit. These magnetic elements 2 are arranged such that a circular air gap 3 is formed within the magnetic circuit 2.

[0051] Furthermore, a voice coil 1, comprising a plurality of coil windings, is suspended in the air gap 3. The windings of the voice coil 1 are arranged such that when an electric current is passed through the coil 1, an electromotive force displaces the voice coil 1 within the air gap 3, thus actuating a diaphragm 7. An alternating current causes the diaphragm 7 to move back and forth, generating an acoustic tone signal.

[0052] With reference to Fig. Figure 2 shows a voice coil control system 51 according to an embodiment of the invention. The voice coil control system 51 comprises a magnetic circuit 2 formed by two concentrically aligned magnetic elements 2. The magnetic elements can be permanent magnets or metal poles. The magnetic circuit 2 is arranged such that a circular air gap 3 is formed within the magnetic circuit 2, which is closed off by the two magnetic elements 2. The circular air gap 3 is an air volume that takes the form of a volume located between two axially aligned cylinders of different widths.

[0053] As is known to those skilled in the art, several alternative voice-coil-based loudspeaker configurations are known in the technical field of loudspeakers and acoustic transducers. These configurations feature different magnetic circuit and air gap configurations, including various configurations of permanent magnets, pole pieces, front and rear plates, housings, and various air gap configurations, including circular, as described above, linear, polygonal, irregular, one or more air gaps, etc. The present invention, as defined in the claims, is therefore not limited to the magnetic circuit and air gap configuration shown in the drawings, but can readily be applied by those skilled in the art to other voice-coil-based transducers.

[0054] A voice coil 1 is suspended in the air gap 3. The voice coil 1 comprises a plurality of voice coil sections 21-22b, with a central voice coil section 21 being arranged centrally and surrounded by an upper voice coil section 22a and a lower voice coil section 22b, each arranged on either side of the main voice coil section, all voice coil sections being axially aligned along a motion axis 4 of the voice coil 1. Each voice coil section comprises a plurality of metal windings that wind around the inner magnetic element 2 and a motion axis 4, as shown in Fig. Figure 2 shows that the voice coil sections are mechanically coupled, but not necessarily electrically coupled, to form the voice coil 1. The mechanical coupling may include a support, such as a tube, mesh, or wire structure made of cardboard, plastic, or metal, e.g., a film.

[0055] The voice coil sections 21-22b are configured such that when an electric current is passed through a voice coil section 21-22b that is at least partially located within the air gap 3 of the magnetic circuit 2, an electromotive force displaces the respective voice coil section 21-22b along the axis of motion 4. Since all voice coil sections 21-22b are mechanically coupled elements of the voice coil 1, an electromotive force generated by any one of the voice coil sections 21-22b will displace the entire voice coil 1 along the axis of motion 4. The displacement of the voice coil 1 along the axis of motion 4 causes the voice coil 1 to push and pull a diaphragm 7 of a loudspeaker 50. The movement of the diaphragm 7 generates an acoustic tone signal.

[0056] The coupling of the voice coil 1 and the diaphragm 7 can be implemented by the aforementioned mechanical coupling of the voice coil section, e.g., by a plastic film tube, or by other support elements known to those skilled in the art, e.g., a spider and a diaphragm surround. The rest position of the voice coil 1 can be controlled by the support elements, such as a spider and / or a diaphragm surround, and a frame, as is known to those skilled in the art. In a preferred embodiment, the overall height of the voice coil is centered in the air gap in the rest state, so that, with three voice coil sections as shown in the examples, the middle voice coil section is aligned with the magnetic circuit and the air gap.

[0057] Since the magnetic field is essentially located within the air gap 3 in the magnetic circuit 2, only those voice coil sections 21-22b that are at least partially located within the air gap can generate a substantial electromotive force when an electric current is applied. In general, the more of a particular voice coil section is contained within the air gap, the greater the force generated when an electric current is applied. With reference to the in Fig. At the time shown in Figure 2, only the voice coil section 21 is located wholly or partially within the air gap 3, while the voice coil sections 22a and 22b are located entirely outside the air gap 3. Since the magnetic field density is highest within the air gap 3 and decreases rapidly outside the air gap 3, only the voice coil section 21 can generate a substantial electromotive force to move the voice coil 1, while the voice coil sections 22a and 22b are sufficiently far from the air gap 3 that the efficiency of converting electrical drive power into electromotive force for the voice coil section 21 is considerably lower and practically negligible compared to the efficiency of converting electrical drive power into electromotive force.

[0058] Windings of voice coil sections 21-22b that are located away from the air gap 3 primarily contribute to excessive heating of the voice coil only when electrical drive power is applied, and contribute only slightly to the displacement of the voice coil 1 along the axis of motion 4. Based on these considerations, it is advantageous to avoid applying power to any voice coil sections 21-22b, e.g., 22a-22b, that are not at least partially located within the air gap at any given time.

[0059] In general, a loudspeaker system aims to reproduce an audio signal 30 by means of the displacement of a voice coil 1, where displacement is the position of the voice coil 1 relative to its rest position. An audio signal 30 can represent different sound intensities, which may require different displacements for reproduction. For example, an audio signal 30 may require a range of displacements that can only be established for the audio signal 30 to be reproduced by utilizing the electromotive force that can be generated by the middle voice coil section 21. For the reproduction of a different audio signal 30, a range of displacements may be required that can only be established using the middle voice coil section 21 together with the upper voice coil section 22a and the lower voice coil section 22b.

[0060] Referring to Fig. 2 Each voice coil section 21-22b receives a control signal 41, 43a-43b. These control signals can be provided in any way, e.g., by a control device, an amplifier, or an external source. The middle voice coil section 21 receives a middle control signal 41, the upper voice coil section 22a receives an upper rectified control signal 43a, and the lower voice coil section 22b receives a lower rectified control signal 43b. The upper rectified control signal 43a and the lower rectified control signal 43b are based on an auxiliary control signal 42. The auxiliary control signal 42 and the middle control signal 41 are based on the audio signal 30 or are even identical to it.

[0061] The control signals 41, 43a-43b are the actual electrical signals that pass through the respective voice coil sections 21-22b to generate an electromotive force to move the voice coil 1 along the axis of motion 4. The control signals 41-43b are supplied to the voice coil sections 21-22b via channels, e.g., cables or wires, preferably electrical connections.

[0062] In the Fig. In the exemplary embodiment shown in 2, the middle control signal 41 and the auxiliary control signal 42 are the tone signal 30, but the invention is not limited to this example.

[0063] The upper and lower rectified control signals 43a-43b can be derived from the rectifier units 16, based on the auxiliary control signal 42. A rectifier unit or a passive rectifier unit can process current asymmetrically, i.e., a rectifier unit can respond in a first way to a current in a first direction and in a second way to a current in a second direction.

[0064] Preferably, a rectifier unit will dampen or block one current direction and allow the opposite current direction to pass through.

[0065] An example of a rectifier unit 16 is a diode 17, which may be characterized by asymmetric conductivity, i.e., low resistance for one current direction and high resistance for the opposite current direction, within the current and / or voltage limits of the diode.

[0066] The two rectifier units 16 of the in Fig. The embodiments shown in two exemplary illustrations can preferably be used to block opposite current directions. If the current of an auxiliary control signal 42 flows in one direction, this current can flow substantially to the lower voice coil section 22b, while its flow to the upper voice coil section 22a is blocked. Similarly, if the current of an auxiliary control signal flows in the opposite direction, this current can flow substantially to the upper voice coil section 22a, while its flow to the lower voice coil section 22b is blocked. This is described further below.

[0067] For one direction of the control signal current, the lower voice coil section 22b, whose rest position lies wholly or partially outside the air gap, can be displaced towards the air gap, while for the opposite current direction it is displaced away from the air gap. By implementing a rectifier unit 16, it is possible to attenuate or block the current of the auxiliary control signal 42 to the lower voice coil section 22b when it is moved away from the air gap, where it is unable to generate a substantial electromotive force. The same principle applies to the upper voice coil section 22a, with the direction in which the current is to be attenuated or blocked preferably being the opposite.

[0068] Since each current direction of the control signals can be assigned to a specific translational or deflection direction of the voice coil depending on the orientation of the magnetic field, the rectifier units can be used to limit the current to the upper and lower coil sections 22a-22b when they are moved translationally away from the air gap. It is noteworthy that the upper rectified control signal 43a and the lower rectified control signal 43b are arranged to supply current flowing in a suitable direction to generate an electromotive force on the voice coil 1, so that the applied audio signal 30 is correctly reproduced by the deflection of the voice coil.

[0069] The voice coil sections 21-22b of the voice coil 1 can be configured in various ways, depending on their relative positioning and dimensions. In the illustrated embodiments, the voice coil 1 comprises three voice coil sections 21-22b, but the present invention, as defined in the claims, can be configured with various other numbers and geometries of voice coil sections. A person skilled in the art would be able to change the geometry or increase the number of voice coil sections, for example, to five voice coil sections, i.e., one middle voice coil section, two upper voice coil sections, and two lower voice coil sections, each of the upper and lower voice coil sections being connected to different rectifier units.

[0070] Referring to the Fig. Figures 3a-3c illustrate the dynamic behavior of the voice coil 1 in one embodiment of the invention.

[0071] Fig. Figure 3a shows a voice coil 1, comprising a middle voice coil section 21, an upper voice coil section 22a, and a lower voice coil section 22b, at a point in time during the application of an audio signal. In the case shown, the displacement required to reproduce the audio signal can be generated solely by the middle voice coil section 21. Depending on the current direction of the auxiliary control signal 42, the current can be damped or blocked either towards the upper voice coil section 22a or towards the lower voice coil section 22b.

[0072] In some embodiments of the invention, a current and / or voltage threshold can be implemented such that neither the upper voice coil section 22a nor the lower voice coil section 22b is activated at similar times as those described in Fig. 3a is supplied with electricity.

[0073] In Fig. 3b an audio signal is applied such that the voice coil 1 was moved in an upward direction 5 at the time shown. Thus, the current of the middle control signal 41 and the auxiliary control signal 42 can have a flow direction that is damped or blocked towards the upper voice coil section 22a.

[0074] Alternatively, in Fig. 3c an audio signal is applied such that the voice coil 1 was moved in a downward direction 6 at the time shown. Thus, the current of the middle control signal 41 and the auxiliary control signal 42 can have a flow direction that is damped or blocked towards the lower voice coil section 22b.

[0075] The Fig. Figures 4a-4b show different embodiments of the invention, both of which include reinforcing means.

[0076] In Fig. 4a An audio signal 30 is fed to an amplifier 12 via an interface 52. The amplifier 12 is powered by a power supply unit 13, e.g., a battery, a DC power supply, or an AC-to-DC power supply. The amplifier 12 has two output channels on which the middle control signal 41 and the auxiliary control signal, respectively, are provided. According to the invention, the amplifier 12 can provide two identical or two different gains to supply the two outputs. The middle control signal 41 is sent to the middle voice coil section 21, and the auxiliary control signal 42 is sent to the rectifier units 16 to generate an upper rectified signal 43a and a lower rectified signal 43b, which are fed to the upper voice coil section 22a and the lower voice coil section 22b, respectively.

[0077] In Fig. In 4b, an audio signal 30 is supplied via an interface 52 to an amplifier 12, which is powered by a power supply unit 13. The amplifier 12 has one output channel, at which a signal is provided that serves both as the middle control signal 41 and as an auxiliary control signal 42. One channel carries the signal to the middle voice coil section 21, and two other channels are connected to diodes 17, which in the embodiment shown function as rectifier units 16. The diodes 17 are arranged with opposite directional characteristics, so that one current direction is primarily supplied to the lower voice coil section 22b, while the opposite current direction is primarily supplied to the upper voice coil section 22a.

[0078] The use of one or more diodes 17 as rectifier units 16 is not limited to embodiments of the invention in which an amplifier 12 with one or more output channels is integrated, since diodes can generally be used as rectifier units in all configurations of the present invention.

[0079] Fig. Figure 5 shows a loudspeaker 50 according to the invention. The loudspeaker 50 receives an audio signal 30, which is applied to a voice coil control system 51 according to the invention.

[0080] A loudspeaker according to the invention can be a passive loudspeaker that does not require a power source but a pre-amplified audio signal, or an active loudspeaker that may require a power source, e.g. for internal amplification, e.g. when receiving a line-level or digital audio signal.

[0081] The Fig. Figures 6a-6c illustrate different configurations of applying the middle control signal 41 and the auxiliary drive signal 42 according to embodiments of the invention.

[0082] In Fig. At 6a, an incoming control signal 46 is supplied to the voice coil 1. This control signal 46 is supplied to the middle voice coil section 21 as the middle control signal 41 and to two diodes 17 to generate an upper rectified control signal 43a and a lower rectified control signal 43b. The diodes 17 are mounted with opposite polarities, so that the upper rectified control signal 43a and the lower rectified control signal 43b each contain currents flowing in opposite directions. The current supplied to the voice coil sections 21-22b is carried out via the output channels 44a-45. These channels are electrically connected to provide a single current output 47 of the voice coil 1.

[0083] In Fig. In 6b, an incoming control signal 46 is supplied to the voice coil 1. This control signal 46 is supplied only to the central voice coil section 21 as a central control signal 41. The signal current leaves the central voice coil section 21 via an output channel 45. This output channel provides the auxiliary control signal 42, which is supplied to two diodes 17 to generate an upper rectified control signal 43a and a lower rectified control signal 43b. The diodes 17 are mounted with opposite polarities, so that the upper rectified control signal 43a and the lower rectified control signal 43b each contain currents flowing in opposite directions. The current of the upper and lower rectified control signal 43a-43b leaves the upper and lower voice coil sections 22a-22b through the output channels 44a-44b, which are electrically connected to provide a single current output 47 of the voice coil 1.

[0084] In Fig. In 6c, a central control signal 41 and an auxiliary control signal 42 are supplied to the voice coil 1. The central control signal is supplied to the central voice coil section 21, while the auxiliary control signal 42 is supplied to two diodes 17 to generate an upper rectified control signal 43a and a lower rectified control signal 43b. The diodes 17 are mounted with opposite directional characteristics, so that the upper rectified control signal 43a and the lower rectified control signal 43b each contain currents flowing in opposite directions.

[0085] The current of the middle control signal 41 leaves the middle voice coil section 21 via the output channel 45, and the current of the upper and lower rectified control signal 43a-43b leaves the upper and lower voice coil sections 22a-22b via the output channels 44a-44b, which are electrically connected to provide a single auxiliary current output 48.

[0086] The in the Fig. The embodiments shown in Figures 6a-6c use diodes 17 as rectifier units 16, but the configurations shown are not limited to the use of diodes 17. Furthermore, the embodiments shown are only selected examples of providing rectified control signals by passive rectification, and the invention is not limited to these examples.

[0087] Fig. Figure 7a shows an alternative embodiment of the invention with a voice coil 1 comprising five different voice coil sections, namely a second upper voice coil section 24a, a first upper voice coil section 23a, a middle voice coil section 21, a first lower voice coil section 23b, and a second lower voice coil section 24b. The upper and lower voice coil sections 23a-24b can be connected to rectifier units 16, similarly to the above description of a voice coil 1 with an upper voice coil section 22a and a lower voice coil section 22b. In other words, a voice coil 1 with five different voice coil sections can, for example, include four rectifier units 16. In this embodiment, four rectifier units 16, such as...Diodes 17 are used, but in other embodiments of the invention, fewer rectifier units 16 can be used for a voice coil 1 comprising five different voice coil sections. For example, one or more rectifier circuits, e.g., two rectifier circuits, can be used to supply rectified control signals to the voice coil section.

[0088] If one or more control signals are supplied to the voice coil 1, a first current direction can only be supplied to the first lower voice coil section 23b and the second lower voice coil section 24b, and a second current direction can only be supplied to the first upper voice coil section 23b and the second upper voice coil section 24b.

[0089] All rectifier units 16 that supply rectified signals to the upper and lower voice coil sections 23a-24b can have different current and / or voltage thresholds. Such a threshold ensures that no current is supplied to the voice coil sections when it is not required. Thus, if the voice coil sections 24a-24b do not need to generate electromotive force to assist the movement of the voice coil 1, rectifier units 16 connected to the outer voice coil sections 24a-24b can attenuate or block current. Furthermore, if the voice coil sections 23a-23b do not need to generate electromotive force to reproduce an applied audio signal, rectifier units 16 connected to the voice coil sections 23a-23b can attenuate or block current.All current and / or voltage threshold values ​​are preferably chosen such that the audio signal can be reproduced without distortion within the limits of the complete voice coil 1, while a minimal current is supplied to the voice coil sections that are not substantially within the air gap and therefore cannot generate any electromotive force.

[0090] Fig. Figure 7b shows a further alternative embodiment of the invention, in which the height of the individual voice coil sections of the voice coil 1 along the direction of the axis of motion 4 is smaller than the air gap 3.

[0091] In preferred embodiments, either the upper voice coil section 22a or the lower voice coil section 22b is capable of generating an electromotive force to move the voice coil 1 to very large displacements when the middle voice coil section 21 is substantially outside the air gap, i.e., when the middle voice coil section 21 leaves the air gap, another voice coil section 22a-22b enters. In such embodiments, an audio signal 30 can be reproduced without distortion by the displacement, even when the middle voice coil section 21 leaves the air gap 3.

[0092] Fig. Figure 8 illustrates a method for generating an upper rectified control signal 43a and a lower rectified control signal 43b based on an auxiliary control signal 42.

[0093] Four charts, P1-P4, show representations of the control signals at different stages. These representations describe the amplitude of the control signals as a function of time. The zero point shown on the four charts P1-P4 indicates the points in time in a control signal at which no current flows in a corresponding section of the voice coil.

[0094] In the Fig.In the exemplary embodiment shown in Figure 8, a mean control signal 41 is supplied to a mean voice coil section 21, a representation of which is shown in Table P1. Additionally, an auxiliary control signal 42 is provided, a representation of which is shown in Table P2. In this embodiment, the representations of the mean control signal in Table P1 and the auxiliary control signal in Table P2 are shown with similar amplitudes. In various other embodiments, the actual current and / or voltage of the mean control signal and the auxiliary control signal may not be the same; that is, the signals may differ in amplitude / gain.

[0095] The auxiliary control signal 42 is supplied to rectifier units 16 to generate an upper rectified control signal 43a and a lower rectified control signal 43b. Since the auxiliary control signal 42 is provided, a first current direction can therefore only be supplied to the lower voice coil section 22b, and a first current direction can only be supplied to the upper voice coil section 22a. This is illustrated in Table P3, which shows a representation of the upper rectified control signal 43a, and in Table P4, which shows a representation of the lower rectified control signal 43b. In Table P3, negative parts of the signal are omitted, while in Table P4, positive parts of the signal are omitted. This represents a preferred embodiment of the invention in which, depending on the current direction, no significant current of the auxiliary control signal is supplied to either the upper voice coil section 22a or the lower voice coil section 22b.

Claims

[1] Method for driving a voice coil (1) of a loudspeaker (5), comprising the steps: Providing a magnetic circuit (2) with an air gap (3) and a voice coil (1) suspended in the air gap (3); Applying an audio signal (30) to the voice coil (1) suspended in the air gap (3) to generate an electromotive force that moves the voice coil (1) along an axis of motion (4); characterized by , that the voice coil (1) comprises a plurality of voice coil sections arranged along the axis of motion (4), wherein the plurality of voice coil sections comprises a middle voice coil section (21), an upper voice coil section (22a) and a lower voice coil section (22b), wherein the upper voice coil section (22a) and the lower voice coil section (22b) are each arranged on both sides of the middle voice coil section (21); wherein the step of applying an audio signal (30) comprises providing a middle control signal (41) based on the audio signal (30) to the middle voice coil section (21) and providing an auxiliary control signal (42) based on the audio signal (30) to the upper voice coil section (22a) and the lower voice coil section (22b), wherein the provision of an auxiliary control signal (42) comprises providing an upper rectified control signal (43a) to the upper voice coil section (22a) and providing a lower rectified control signal (43b) to the lower voice coil section (22b); wherein the upper rectified control signal (43a) is provided by attenuation or blocking a first current direction of the auxiliary control signal (42) by rectification; wherein the lower rectified control signal (43b) is provided by attenuation or blocking a second current direction of the auxiliary control signal (42) by rectification; wherein the first and second current directions of the auxiliary control signal (42) are opposite current directions; wherein the middle control signal (41) is electrically fed in parallel to the middle voice coil section (21), the upper rectified control signal (43a) to the upper voice coil section (22a) and the lower rectified control signal (43b) to the lower voice coil section (22b). [2] Method for controlling a voice coil according to claim 1, wherein the rectification of the auxiliary control signal (42) is half-wave rectification. [3] Method for controlling a voice coil according to one of the preceding claims, wherein providing the upper rectified control signal (43a) comprises processing the auxiliary control signal (42) using an upper rectifier unit (16), and providing the lower rectified control signal (43b) comprises processing the auxiliary control signal (42) using a lower rectifier unit (16). [4] Method for controlling a voice coil according to claim 3, wherein the upper rectifier unit (16) has a passive rectifier circuit, and / or wherein the lower rectifier unit (16) has a passive rectifier circuit. [5] Method for driving a voice coil according to claim 3 or 4, wherein the upper rectifier unit (16) and the lower rectifier unit (16) each have a half-wave rectifier circuit. [6] Method for controlling a voice coil according to one of claims 3-5, wherein the upper rectifier unit (16) has a diode (17) and wherein the lower rectifier unit (16) has a diode (17). [7] Method for controlling a voice coil according to claim 6, wherein the diodes (17) are coupled with a forward voltage drop compensation. [8] Method for controlling a voice coil according to one of the preceding claims, wherein the mean control signal (41) and the auxiliary control signal (42) are provided by one or more amplifiers (12). [9] Method for controlling a voice coil according to one of the preceding claims, wherein providing an upper rectified control signal (43a) comprises amplifying the auxiliary control signal (42) and wherein providing a lower rectified control signal (43b) comprises amplifying the auxiliary control signal (42). [10] Method for controlling a voice coil according to one of the preceding claims, wherein the auxiliary control signal (42) has an amplitude different from the mean control signal (41). [11] Method for controlling a voice coil according to one of claims 1-9, wherein the auxiliary control signal (42) has the same amplitude as the mean control signal (41). [12] Method for controlling a voice coil according to one of the preceding claims, wherein the upper voice coil section (22a) is a first upper voice coil section (23a), the lower voice coil section (22b) is a first lower voice coil section (23b), the upper rectified control signal (43a) is a first upper rectified control signal, the lower rectified control signal (43b) is a second lower rectified control signal, and the auxiliary control signal (42) is a first auxiliary control signal; wherein the plurality of voice coil sections arranged along the axis of motion (4) further comprises a second upper voice coil section (24a) and a second lower voice coil section (24b), wherein the second upper voice coil section (24a) and the second lower voice coil section (24b) are each arranged on both sides of the group of voice coil sections comprising the first upper voice coil section (23a), the middle voice coil section (21) and the first lower voice coil section (23b); wherein the step of applying an audio signal (30) further comprises providing a second auxiliary control signal based on the audio signal (30) to the second upper voice coil section (24a) and the second lower voice coil section (24b), wherein the provision of a second auxiliary control signal comprises providing a second upper rectified control signal to the second upper voice coil section (24a) and providing a second lower rectified control signal to the second lower voice coil section (24b); wherein the second upper rectified control signal is provided by attenuation or blocking a first current direction of the second auxiliary control signal (42) by rectification; and wherein the second lower rectified control signal is provided by attenuation or blocking a second current direction of the second auxiliary control signal (42) by rectification. [13] Voice coil control system (51) of a loudspeaker (50), comprising: a magnetic circuit (2) with an air gap (3); a voice coil (1) suspended in the air gap (3), wherein the voice coil (1) has a plurality of voice coil sections arranged along the axis of motion (4), the plurality of voice coil sections comprising a middle voice coil section (21), an upper voice coil section (22a) and a lower voice coil section (22b) includes the upper The voice coil section (22a) and the lower voice coil section (22b) are each arranged on both sides of the middle voice coil section (21); one or more passive rectifier units (16) arranged to supply an upper rectified control signal (43a) to the upper voice coil section (22a) and a lower rectified control signal (43b) to the lower voice coil section (22b); wherein a middle control signal (41) is electrically fed in parallel to the middle voice coil section (21), the upper rectified control signal (43a) to the upper voice coil section (22a) and the lower rectified control signal (43b) to the lower voice coil section (22b). [14] Voice coil control system according to claim 13, wherein the one or more rectifier units (16) comprise either one or more rectifier circuits or one or more diodes (17). [15] Voice coil control system according to one of claims 13 or 14, wherein the voice coil control system (51) is arranged to receive an audio signal (30) and supply a mean control signal (41) based on the audio signal (30) to the mean voice coil section (21) and supply an auxiliary control signal (42) based on the audio signal (30) to one or more passive rectifier units (16). [16] Voice coil control system according to one of claims 13-15, wherein the voice coil control system (51) comprises two rectifier units (16), each of the two rectifier units (16) being arranged such that it provides either an upper rectified control signal (43a) or a lower rectified control signal (43b) based on the auxiliary control signal (42). [17] Voice coil control system according to claim 16, wherein an upper rectifier unit of one or more rectifier units (16) is arranged to process the auxiliary control signal (42) by damping or blocking a first current direction of the auxiliary control signal (42) in order to provide the upper rectified control signal (43a); wherein a lower rectifier unit of one or more rectifier units (16) is arranged to process the auxiliary control signal (42) by attenuating or blocking a second current direction of the auxiliary control signal (42) in order to provide the lower rectified control signal (43b); and wherein the first and second current directions of the auxiliary control signal (42) are opposite current directions. [18] Voice coil control system according to one of claims 13-17, wherein the upper voice coil section (22a) is displaced relative to the middle voice coil section (21) along a first displacement direction along the axis of motion (4), the lower voice coil section (22b) is displaced relative to the middle voice coil section (21) along a second displacement direction along the axis of motion (4), and the upper voice coil section (22a) and the lower voice coil section (22b) are arranged symmetrically around the middle voice coil section (21), wherein the first displacement direction and the second displacement direction are opposite directions along the axis of motion (4). [19] Voice coil control system according to one of claims 13-18, wherein the height of the voice coil sections is individually either smaller, larger and / or of the same height as the height of the air gap (3) along the axis of motion (4). [20] Loudspeaker (50) comprising a diaphragm (7); an interface (52) configured to receive an audio signal (30); and a voice coil drive system (51) according to any one of claims 13 to 19.

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