Search

DE-102020102904-B4 - SPEAKERS WITH PASSIVELY CONTROLLED VOYAGE COIL SECTIONS

DE102020102904B4DE 102020102904 B4DE102020102904 B4DE 102020102904B4DE-102020102904-B4

Abstract

The invention relates to a method for driving 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 driving system and a loudspeaker with a voice coil driving system.

Inventors

  • George Albert Bullimore
  • Ruben Minoru Tuemp Millyard

Assignees

  • TYMPHANY ACOUSTIC TECHNOLOGY (HUIZHOU) CO., LTD.

Dates

Publication Date
20260513
Application Date
20200205

Claims (20)

  1. A method for controlling a voice coil (1) of a loudspeaker (5), comprising the steps of: 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 in 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 central 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 central 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 attenuating or blocking a first current direction of the auxiliary control signal (42) by rectification; wherein the lower rectified control signal (43b) is provided by attenuating 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 supplied 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 a 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 controlling 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 driving a voice coil according to one of the 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 driving a voice coil according to one of the Claims 1 - 9 , wherein the auxiliary control signal (42) has the same amplitude as the mean control signal (41).
  12. A method for controlling a voice coil according to any 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 attenuating 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 attenuating 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), the voice coil (1) having 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), the upper voice coil section (22a) and the lower voice coil section (22b) being arranged on either side 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); where 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 the 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 an auxiliary control signal (42) based on the audio signal (30) to the provides one or more passive rectifier units (16).
  16. Voice coil control system according to one of the Claims 13 - 15 , wherein the voice coil control system (51) comprises two rectifier units (16), each of the two rectifier units (16) being arranged to provide 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 attenuating or blocking a first current direction of the auxiliary control signal (42) 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) 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 the 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 the 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 one of the Claims 13 until 19 .

Description

Field of invention 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 With reference to 1a-1b A voice coil drive system for a loudspeaker is illustrated in the technical drawing. The voice coil drive system is equipped with a voice coil 1, which comprises a multitude of coil windings. The coil 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 tone signal. 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. JP S59 - 12 693 A This concerns a loudspeaker, especially a bass speaker with good playback efficiency. JP 2009 - 89 260 A refers to a loudspeaker with reduced loss during operation. 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 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. One aspect of the invention relates to a method for controlling a voice coil of a loudspeaker according to claim 1. 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 in order to produce acoustic sounds. The magnetic field can be generated by a magnet, such as a permanent magnet or an electromagnet, present in a magnetic circuit. The magnetic circuit may include an air gap in which the voice coil moves back and forth, thereby producing acoustic sounds by moving the loudspeaker diaphragm back and forth. 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. 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, with the first and second current directions being opposite directions. When current flows through the voice coil windings in a first 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 along the axis of motion, enabling the reciprocating motion of the voice coil within the air gap. An audio signal is typically a type of electronic signal. In various forms, it can be an analog signal, continuous or pulsed. The signal type can be digital. When referring to the amplitude of an audio signal, it can be the amplitude of an analog audio signal or the audio signal level of a digital audio signal. 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. According to various embodiments of the invention