JP2013157972A - Digital speaker device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a digital speaker device capable of reproducing good sound without generating distortion sound even when any of a plurality of voice coils are disconnected and do not operate in a conductive state.SOLUTION: The digital speaker device comprises: a speaker system including a plurality of m voice coils; and a drive circuit having a plurality of m output terminals. The drive circuit includes: a signal conversion output section for converting an input signal into output signals to be supplied to the respective voice coils and outputs the output signals to the plurality of m output terminals; a current conduction detecting section for detecting whether or not the plurality of m voice coils are in a conductive state; and a control section for controlling the signal conversion output section and the current conduction detecting section. When the current conduction detecting section detects that the number n (≤m) of the voice coils in a conductive state is less than the number m, the control section controls the signal conversion output section to output the output signals to the n output terminals excluding the output terminal corresponding to the voice coil in a non-conductive state.

Description

  The present invention relates to a digital speaker device that performs sound reproduction using a speaker system including a plurality of voice coils.

  In a speaker that reproduces sound waves in the audible sound range, a direct radiation type electrodynamic speaker that vibrates the speaker diaphragm by supplying the voice signal amplified by the amplifier to the voice coil arranged in the magnetic gap of the magnetic circuit, Generally used. In electrodynamic speakers, analog signals or digital signals subjected to PWM modulation or the like are mainly supplied to a single voice coil, while a speaker including a multi-voice coil corresponding to a bit of a multi-bit digital signal. There is a digital speaker device that reproduces sound by using a system and a dedicated drive circuit. There are various types of speaker systems of digital speaker devices and methods of driving circuits thereof.

  For example, conventionally, there is a voice coil tap corresponding to a parallel digital value of a digital signal, and each voice coil tap has a number of windings proportional to the weight of the corresponding number of bits. There is a digital speaker that has a volume adjustment coil magnetically coupled to a voice coil and adjusts the volume by adjusting a current flowing through the volume adjustment coil (Patent Document 1).

  Further, conventionally, using an electromagnetically coupled speaker, in the gap of the magnetic circuit having a gap between the center pole portion and the plate, the center pole portion has the front side of the speaker from the position of the thickness P of the plate and A primary coil, which is a drive coil, with a winding width L extended to the rear side is fixed, and the center pole portion 12 is located at a position on the front side and rear side of the speaker from the position of the winding width L of the primary coil. And has an outer peripheral surface facing the rear or oblique rear of the speaker and an outer peripheral surface facing the front or oblique front of the speaker, and is fixed to a cone in the gap to constitute a short coil. There is one which arranges the next coil (patent document 2).

  Also, conventionally, there is provided a digital speaker system for driving a digital speaker having s sets of digital signal terminals, a ΔΣ modulator that modulates a digital input signal and outputs an n-bit digital signal, and the ΔΣ modulator. A post filter that outputs an m-bit digital signal that is mismatch-shaped from the n-bit digital signal and a part of the m-bit digital signal corresponding to the s sets of digital signal terminals are input. S drive circuits for outputting digital signals, each of the s drive circuits being connected to a first input terminal of a corresponding digital signal terminal; and A second output circuit connected to a second input terminal paired with the first input terminal of the digital signal terminal; There is provided a digital speaker driving device that takes at least three digital signal output states in accordance with a combination of a first digital signal input to one output circuit and a second digital signal input to the second output circuit. Yes (Patent Document 3).

Japanese Patent No. 2522184 Japanese Patent Application Laid-Open No. 10-051888 JP 2010-028784 A

  However, in a speaker system including a multi-voice coil and a digital speaker device using a dedicated drive circuit, it is assumed that the operation of all the plurality of voice coils is good, and one of the voice coils is disconnected. When the energization operation is not performed, there is a problem that good sound reproduction cannot be performed. In addition, the digital speaker device has a problem in that when an audio is played back even if any one of the voice coils is disconnected, the original operation is not realized, so that a distorted sound is generated. When any one of the voice coils cannot be energized, there is a problem that the conversion efficiency to sound waves is lowered due to a decrease in driving force to the speaker diaphragm, and the reproduced sound pressure level is lowered.

  The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is a digital speaker device that reproduces sound using a speaker system including a plurality of voice coils. It is an object of the present invention to provide a digital speaker device that can reproduce sound well even when the voice coil is disconnected and does not operate when energized and does not generate distorted sound.

  A digital speaker device according to the present invention is a digital speaker device including a speaker system including a plurality of m voice coils, and a drive circuit having a plurality of m output terminals connected to the voice coils, respectively. Whether or not the signal conversion output unit that converts the signal into an output signal to be supplied to each voice coil and outputs it to a plurality of m output terminals and the plurality of m voice coils of the speaker system connected to the output terminals can be energized. And a control unit that controls the signal conversion output unit and the energization detection unit, and the energization detection unit has a number n (≦ m) of voice coils that can be energized less than a plurality of m. The control unit controls the signal conversion output unit so that it outputs to a number n of output terminals excluding the output terminal corresponding to the voice coil that cannot be energized. That.

  Preferably, in the digital speaker device of the present invention, when the energization detection unit detects that the number n of voice coils that can be energized is less than a plurality of m, the control unit substantially reduces the output voltage of the output signal ( The signal conversion output unit is controlled so that it is multiplied by m / n) and output to several n output terminals.

  Preferably, in the digital speaker device of the present invention, a plurality of m voice coils of the speaker system are connected to a single speaker diaphragm.

  The operation of the present invention will be described below.

  The digital speaker device of the present invention is a digital speaker device comprising a speaker system including a plurality of m voice coils and a drive circuit having a plurality of m output terminals connected to the voice coils. The speaker system constituting this digital speaker device is preferably a system in which a plurality of m voice coils are connected to a single speaker diaphragm. Alternatively, the speaker system may be a system in which a plurality of speakers each having a plurality of m voice coils connected to individual speaker diaphragms are arranged close to each other.

  In the digital speaker device of the present invention, the drive circuit converts the input signal into an output signal supplied to each voice coil and outputs the output signal to a plurality of m output terminals, and the speaker connected to the output terminal. An energization detection unit that detects whether or not a plurality of m voice coils of the system can be energized, and a control unit that controls the signal conversion output unit and the energization detection unit. The energization detection unit of the drive circuit can perform an operation of detecting the number n (≦ m) of voice coils of the speaker system that can be energized before the audio reproduction operation or during the audio reproduction operation.

  Therefore, when the control unit of the drive circuit detects that the number n of voice coils that can be energized is less than a plurality of m, the control unit of the drive circuit transfers to a number n of output terminals excluding output terminals corresponding to voice coils that cannot be energized. The signal conversion output unit is controlled to output. As a result, in this digital speaker device, even when any voice coil of the speaker system is disconnected and the energization operation is not performed, or when it is not properly connected, good sound reproduction is possible and distortion sound is not generated. It can be prevented from occurring.

  In the digital speaker device of the present invention, when the energization detecting unit detects that the number n of voice coils that can be energized is smaller than a plurality of m, the control unit approximates the output voltage of the output signal (m / N) The signal conversion output unit is controlled so as to be multiplied and output to several n output terminals. Therefore, even when there is a voice coil that cannot be energized, the reproduction sound pressure level does not decrease and good sound reproduction is possible.

  The digital speaker device of the present invention is capable of good sound reproduction even when any one of a plurality of voice coils is disconnected and does not operate, so that distortion sound is not generated and the reproduction sound pressure level does not decrease. A speaker device can be provided.

It is a figure explaining the digital speaker apparatus 1 by preferable embodiment of this invention. Example 1 It is a table | surface explaining the disconnection detection and coil control in the digital speaker apparatus 1 by preferable embodiment of this invention. Example 1 It is a flowchart in the control circuit of the digital speaker apparatus 1 by preferable embodiment of this invention. Example 1

  Hereinafter, although the digital speaker apparatus by preferable embodiment of this invention is demonstrated, this invention is not limited to these embodiment.

  FIG. 1 is a diagram for explaining a digital speaker device 1 according to a preferred embodiment of the present invention. Specifically, FIG. 1 is a block diagram showing a configuration of the digital speaker device 1. FIG. 2 is a table for explaining disconnection detection and coil control in the digital speaker device 1, and FIG. 3 is a flowchart in the control circuit of the digital speaker device 1. In addition, illustration and description of a part of the structure unnecessary for the description, an internal structure, and the like are omitted.

  The digital speaker device 1 includes a speaker system 2 and a drive circuit 3. The digital speaker device 1 outputs the digital audio signal input to the input terminal Input of the drive circuit 3 to the speaker system 2 without converting it into an analog audio signal via the D / A converter, and the speaker system 2 outputs the audio. It is an acoustic reproduction apparatus that performs audio reproduction by converting a signal into a sound wave. In the digital speaker device 1 of the present embodiment, the speaker system 2 includes a single speaker diaphragm 4 and a voice coil 5 including a plurality of m = 4 coils 51 to 54 connected thereto.

  Specifically, the voice coil 5 of the speaker system 2 is connected to the speaker diaphragm 4 on one end side of the bobbin 50 by winding coils 51 to 54 around a cylindrical bobbin 50. Further, the coils 51 to 54 are arranged so as to be able to vibrate in a magnetic gap (not shown) of a magnetic circuit (not shown). Therefore, when a current based on an audio signal is supplied to the coils 51 to 54, a driving force for vibrating the speaker diaphragm 4 and the voice coil 5 is generated. In FIG. 1, the magnetic circuit in the speaker system 2, and other components such as an edge and a damper (not shown) that support the speaker diaphragm 4 and the voice coil 5 so as to vibrate are not shown and described. doing.

  The drive circuit 3 corresponding to the speaker system 2 converts an input signal into an output signal to be supplied to each of the coils 51 to 54, and outputs the output signal from the signal conversion output unit 6 as power. An amplifying unit 7 for amplifying and an output terminal group 10 connected to the voice coil 5 of the speaker system 2 are included. Further, the drive circuit 3 controls the energization detection unit 8 that detects whether or not the voice coil 5 of the speaker system 2 connected to the output terminal group 10 can be energized, and the signal conversion output unit 6 and the energization detection unit 8. And a control unit 9 for performing. Specifically, the control unit 9 is a microcomputer that controls the entire digital speaker device 1 and may include an operation part such as volume adjustment.

  The signal conversion output unit 6 of the drive circuit 3 can convert the input signal into four output signals supplied to the respective coils 51 to 54 and output them. The four output signals from the signal conversion output unit 6 are amplified by the four power amplifiers of the amplification unit 7 and output to the output terminal group 10. The signal conversion output unit 6 can perform signal conversion according to the number of outputs and output a signal even when the number of coils to be output is four or less. The amplifying unit 7 may be an amplifier that amplifies an audio signal, may be a switching amplifier that performs class D amplification, and may be included in the signal conversion output unit 6. Further, the signal conversion output unit 6 through the amplification unit 7 may be a digital speaker driving circuit including a PWM modulator or a ΔΣ modulator.

  The output terminal group 10 includes four sets of output terminals 11 to 14 with positive and negative output terminals as a set. Specifically, the four output signals from the signal conversion output unit 6 of the drive circuit 3 are supplied to the four output terminals 11A, 12A, 13A, and 14A of the output terminal group 10. One ends of coils 51, 52, 53, 54 of the voice coil 5 of the speaker system 2 are connected to the output terminals 11A, 12A, 13A, 14A, respectively. The other ends of the coils 51, 52, 53, 54 are connected to the four output terminals 11 B, 12 B, 13 B, 14 B of the output terminal group 10. One end of the current detection resistor 15 of the energization detection unit 8 is connected to the output terminals 11B, 12B, 13B, and 14B, and the other end of the current detection resistor 15 is grounded. That is, the current detection resistor 15 is a resistor having a resistance value sufficiently smaller than the DC resistance value of the coils 51 to 54 and is connected in series to each of the coils 51 to 54. Even when the amplification unit 7 is a BTL amplifier using two switching elements, the current detection resistor 15 only needs to be connected in series to the coils 51 to 54 of the voice coil 5 to be BTL-connected.

  Therefore, in the energization detection unit 8, the internal energization detection circuit can detect the current flowing through the coils 51 to 54 by detecting the voltage across the current detection resistor 15. When an input signal that is an audio signal or a small DC voltage or noise signal that is a test signal is supplied to the coils 51 to 54, both ends of the current detection resistor 15 are provided when the coils 51 to 54 can be energized. A predetermined voltage can be detected. On the other hand, when the coils 51 to 54 cannot be energized, the voltage is not detected at both ends of the current detection resistor 15, so that the energization detection unit 8 can energize the coils 51 to 54 of the voice coil 5. Whether or not can be detected. The case where the energization is impossible includes the case where the coils 51 to 54 are disconnected and the energization operation is not performed, or the case where the speaker system 2 and the drive circuit 3 are not properly connected. In this embodiment, a coil that can be energized is denoted as ix, and a coil that cannot be energized is denoted as iz.

  The control unit 9 of the digital speaker device 1 operates the energization detection unit 8 of the drive circuit 3 before or during the sound reproduction operation, and the number of coils ix that can be energized in the speaker system 2. An operation for detecting n (≦ m) is performed. As described above, the signal conversion output unit 6 of the drive circuit 3 can output a signal by performing signal conversion according to the number of outputs even when the number of coils to be output is four or less. When the unit 9 detects that the number n of the coils ix that can be energized is less than four, which is the upper limit of the present embodiment, the number n excluding the output terminal corresponding to the coil iz that cannot be energized. The signal conversion output unit 6 is controlled to output to the output terminal group 10.

  For example, as shown in the table of FIG. 2, when all of the coils 51 to 54 can be energized (circles), the signal conversion output unit 6 of the drive circuit 3 outputs to all the output terminal groups 10. When any one of the coils 51 to 54 is disconnected and cannot be energized (x mark), the signal conversion output unit 6 of the drive circuit 3 assumes that the number n of the coils ix that can be energized is three. Output to three sets of output terminal groups 10 excluding output terminals corresponding to coils iz that cannot be energized. Similarly, when any two of the coils 51 to 54 are disconnected and cannot be energized (x mark), the signal conversion output unit 6 of the drive circuit 3 has two n number of coils ix that can be energized. Assuming that there is a current, the output is output to two sets of output terminals 10 excluding the output terminal corresponding to the coil iz that cannot be energized. Further, when any three of the coils 51 to 54 are disconnected and cannot be energized (x mark), the signal conversion output unit 6 of the drive circuit 3 has the number n of coils ix that can be energized. Are output to a set of output terminal groups 10 excluding output terminals corresponding to coils iz that cannot be energized. When all of the coils 51 to 54 cannot be energized (x mark), the signal conversion output unit 6 of the drive circuit 3 stops output to all the output terminal groups 10.

  FIG. 3 is a flowchart for explaining the operation of the control unit 9 of the drive circuit 3 described above. For example, the control unit 9 starts the operation of the energization detection unit 8 of the drive circuit 3 before the sound reproduction operation (S001). The control unit 9 initializes the counter i with the detection of energization / disconnection (S002). Next, disconnection detection of the i-th coil is performed (S003), and it is performed in order until the disconnection detection is completed for all the coils 51 to 54 (S004: No). When the disconnection detection is completed for all the coils 51 to 54 (S004: Yes), the control unit 9 specifies the coil iz that cannot be energized and obtains the total number n of the coils ix that can be energized (S005). When the total number n of the coils ix that can be energized is equal to the number m of all the coils (S006: Yes), the control unit 9 outputs the signal conversion output unit 6 to all the output terminal groups 10. Setting is made (S007). When it is detected that the total number n of the coils ix that can be energized is smaller than the number m of all the coils (S006: No), the control unit 9 outputs an output terminal group corresponding to the coils ix that can be energized. The output is set to 10 (S008). Then, the control unit 9 controls the signal conversion output unit 6 so as to multiply the output voltage of the output signal by (m / n) and output it to several n output terminals (S009). Finally, when the energization / disconnection detection is not completed (S010: No), the control unit 9 returns to the initialization step (S002), and when completed (S010: Yes), the control unit 9 ends (S011).

  Therefore, in the digital speaker device 1 of the present embodiment, even when any of the coils 51 to 54 of the voice coil 5 of the speaker system 2 includes the coil iz that cannot be energized, the reproduced sound pressure level does not decrease. Good sound reproduction becomes possible. For example, when two of the four coils iz that cannot be energized are detected, the signal conversion output unit 6 can energize by multiplying the output voltage of the output signal by 2 (= 4/2). It outputs to the two coils ix and does not output to the coil iz that cannot be energized. As a result, not only does distortion sound occur, but the reproduction sound pressure level can be made substantially equal when all four coils can be energized, so that the user does not experience a sense of volume. The control unit 9 operates the energization detection unit 8 continuously or intermittently during reproduction of the audio signal, and appropriately changes the signal conversion output unit 6 if the energization / disconnection state of the voice coil 5 changes. You may change the setting.

  In the digital speaker device 1 of the present embodiment, the number of coils of the voice coil 5 of the speaker system 2 is four, but may be two or more corresponding to the drive circuit 3. The voice coil 5 of the speaker system 2 has coils 51 to 54 wound around a cylindrical bobbin 50 and connected to the speaker diaphragm 4 on one end side of the bobbin 50. The voice coil 5 may be connected so as to be distributed behind the diaphragm 4. Alternatively, the speaker system 2 may be a system in which a plurality of speakers each having a plurality of m of voice coils 5 connected to individual speaker diaphragms 4 are arranged close to each other.

  The digital speaker device of the present invention includes not only a stereo device for reproducing a digital audio signal or a multi-channel surround sound reproducing device, but also a speaker incorporated in a video / audio device such as a display, or a speaker for reproducing audio. The present invention can also be applied to game machines such as a game machine having a cabinet and a slot machine.

DESCRIPTION OF SYMBOLS 1 Digital speaker apparatus 2 Speaker system 3 Drive circuit 4 Speaker diaphragm 5 Voice coil 6 Signal conversion output part 7 Amplification part 8 Current supply detection part 9 Control part 10 Output terminal group 11-14 Output terminal 15 Current detection resistance

Claims (3)

A digital speaker device comprising: a speaker system including a plurality of m voice coils; and a drive circuit having a plurality of m output terminals respectively connected to the voice coils.
A drive circuit converts an input signal into an output signal supplied to each voice coil and outputs it to a plurality of m output terminals, and a plurality of m voice coils of a speaker system connected to the output terminal. An energization detection unit that detects whether or not energization is possible, and a control unit that controls the signal conversion output unit and the energization detection unit,
When the energization detection unit detects that the number n (≦ m) of voice coils that can be energized is less than a plurality of m, the control unit is a number n of units excluding output terminals corresponding to voice coils that cannot be energized. Control the signal conversion output unit to output to the output terminal,
Digital speaker device. When the energization detecting unit detects that the number n of the voice coils that can be energized is smaller than the plurality m, the control unit substantially increases the output voltage of the output signal by (m / n) times. And controlling the signal conversion output unit to output to the number n of the output terminals,
The digital speaker device according to claim 1. A plurality of m of the voice coils of the speaker system are coupled to a single speaker diaphragm;
The digital speaker device according to claim 1 or 2.

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