JP2013125975A - Loudspeaker device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a simplified loudspeaker device with few noises.SOLUTION: A loudspeaker device for emitting acoustic signals comprises: an optical sensor 3 provided on a radiation face side of the acoustic signals of the loudspeaker device and converting received optical signals into electric signals; a signal processing section 7 for generating the electric signals given to a voice coil on the basis of the electric signals; a magnetic circuit 1 fixed to a frame 2 of a loudspeaker and having a magnetic gap 15; a voice coil 8 arranged in the magnetic gap 15 and provided with the electric signals; and a diaphragm 4 supported by the frame 2, vibrated together with the voice coil 8 and emitting the acoustic signals.

Description

  The present invention relates to a speaker device that converts an electrical signal into sound. In particular, the present invention relates to a speaker device that reproduces sound by optical wireless communication.

  In movie theaters, concert halls, video conferences, and the like, three-dimensional acoustic technology such as wavefront synthesis using a large number of speakers is used to faithfully reproduce the sound field. For the wavefront synthesis method, see Non-Patent Document 1, for example.

  However, when a large number of speakers are simultaneously driven by wire, the amount of wiring increases, resulting in an increase in cost and noise. Therefore, in order to reduce the amount of wiring, a technique using a wired serial communication interface is proposed in Non-Patent Document 2, for example, and a wireless speaker system using RF radio waves is proposed in Non-Patent Document 3, for example.

Gunther Theile, Helmut Wittek, “Wave field synthesis: A promising spatial audio rendering concept”, Acoust. Sci. And Tech., 25 (6), 2004. S. Lee, T. Kim, J. Byun, Y. Chung, M. Song, “Integrated control system of multichannel audio signals for serial transmission”, Proc. Of IEEE APCCAS 2008, pp. 1446-1449, Nov 2008. Cirrus Logic Inc., “Digital wireless loudspeaker system”, European Patent Specification EP 1 135 969 B1.

  However, even if a wired serial communication interface is used as in Non-Patent Document 2, if there are many speakers, the amount of wiring may still increase. In addition, in a wireless speaker system using RF radio waves as in Non-Patent Document 3, noise may be generated due to electromagnetic interference caused by a magnet included in the speaker.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a speaker device that is simpler than the prior art and generates less noise than the prior art.

  A speaker device according to an aspect of the present invention is a speaker device for emitting an acoustic signal, provided on the radiation surface side of the acoustic signal of the speaker device, and an optical sensor that converts a received optical signal into an electrical signal; A signal processing unit that generates an electric signal to be given to the voice coil based on the electric signal, a magnetic circuit that is fixed to the speaker frame and has a magnetic gap, a voice coil that is arranged in the magnetic gap and is given an electric signal, And a diaphragm that is supported by the frame and vibrates together with the voice coil to emit an acoustic signal.

  By driving the speaker device with an electric signal based on the optical signal received by the optical sensor provided on the radiation surface side of the acoustic signal, the speaker device can be simplified as compared with the related art. In addition, by using an optical signal instead of an RF radio wave, the influence of electromagnetic interference caused by the magnet of the speaker is reduced, and the generation of noise is reduced as compared with the prior art.

The figure for demonstrating the speaker apparatus of 1st embodiment. The figure for demonstrating the speaker apparatus of 1st embodiment. The figure for demonstrating the signal processing part 7 of 1st embodiment. The figure for demonstrating the speaker apparatus of 2nd embodiment. The figure for demonstrating the signal processing part 7 of 2nd embodiment. The figure for demonstrating the speaker apparatus of 3rd embodiment. The figure for demonstrating the change of the intensity | strength of the optical signal according to the distance of a lens and the optical sensor 3. FIG. The equivalent circuit of the speaker apparatus of 3rd embodiment.

  Embodiments of the present invention will be described below with reference to the drawings.

[First embodiment]
First, a first embodiment of a speaker device will be described with reference to FIGS. 1 and 2. FIG. 1 is a front view of the speaker device of the first embodiment, and FIG. 2 is a cross-sectional view of the speaker device of the first embodiment shown in FIG.

  The magnetic circuit 1 includes a magnet 11 and three yokes 12, 13, and 14. The magnet 11 has a cylindrical shape and includes a through hole 11a. Each of the three yokes 12, 13, and 14 has a ring shape and is laminated so that the central axes thereof coincide with each other. The inner diameter of the yoke 14 is smaller than the inner diameters of the yokes 12 and 13, and the yokes 12, 13, and 14 have a cup shape as a whole. Magnets 11 are arranged on the bottom surfaces of the cup-shaped yokes 12, 13 and 14. The outer peripheral surface of the magnet 11 and the inner peripheral surface of the yoke 12 are opposed to each other via an annular magnetic gap 15. As described above, the magnetic circuit 1 includes the magnetic air gap 15.

  The magnetic circuit 1 is fixed to the frame 2. In this example, the end face of the yoke 12 and one end of the frame 2 are fixed. The frame 2 has a shape formed by a frustoconical outer peripheral surface. A connecting portion 21 is provided on the frame 2. The connection unit 21 electrically connects the cables 81 and 82.

  A ring-shaped edge 41 is attached to the other end of the frame 2. The edge 41 supports the diaphragm 4 at a predetermined position so as not to disturb the vibration of the diaphragm 4.

  The diaphragm 4 is supported by the frame 2 via the edge 41. The diaphragm 4 has a cone shape in this example, but may have another shape.

  A center cap 5 is attached to the center of the diaphragm 4. Since the center cap 5 vibrates with the diaphragm 4, the center cap 5 may be considered as a part of the diaphragm 4, or the center cap 5 may be considered as a member different from the diaphragm 4. The center cap 5 also functions as a dust cap that prevents dust and dust from entering the speaker device.

  When the center cap 5 is considered as a part of the diaphragm 4, a part or all of the diaphragm 4 including the center cap 5 is made of a light transmissive material. When the center cap 5 is considered to be a member different from the diaphragm, a part or all of the center cap 5 is made of a material having optical transparency. The material having optical transparency is, for example, acrylic. An optical signal that passes through the light-transmitting portion is input to the optical sensor 3. The optical sensor 3 converts the received optical signal into an electrical signal.

  A cylindrical voice coil bobbin 6 is attached to the center of the diaphragm 4. The voice coil bobbin 6 is inserted into the magnetic gap 15 of the magnetic circuit 1. As a material of the voice coil bobbin 6, for example, paper, plastic, or aluminum foil is used. The voice coil bobbin 6 is supported by the frame 2 via a damper 61.

  A voice coil 8 is wound around the voice coil bobbin 6. The voice coil bobbin 6 is inserted into the magnetic gap 15 of the magnetic circuit 1, and the voice coil 8 is also arranged in the magnetic gap 15. The voice coil 8 is electrically connected to the signal processing unit 7 via the cable 81, the connection unit 21, and the cable 82. The cable 81 is disposed at a position that does not interfere with the optical signal received by the optical sensor 3.

  The optical sensor 3 is provided on the acoustic signal emission surface side of the speaker device. In this example, the optical sensor 3 is disposed on the back side of the center cap 5. The optical sensor 3 is disposed at a position where an optical signal from the outside of the speaker device can be received. In this example, as described above, a part or the whole of the diaphragm 4 or a part or the whole of the center cap 5 is made of a light transmissive material. The optical sensor 3 is disposed at a position where the light transmitted through the light-transmitting portion can be received. The optical sensor 3 may be fixed by the frame 2 or the magnetic circuit 1, or may be supported by the diaphragm 4, the center cap 5, or the voice coil bobbin 6. For example, the diameter of the optical sensor 3 is not more than half of the diameter of the through hole 11a of the magnet 11. The optical sensor 3 outputs a larger electrical signal as the received optical signal is larger. That is, if the optical signal received by the optical sensor 3 is a digital signal, the electrical signal converted by the optical sensor 3 is a digital signal, and if the optical signal received by the optical sensor 3 is an analog signal, the electrical sensor 3 The converted electrical signal is an analog signal, and if the optical signal received by the optical sensor 3 is a modulated signal, the electrical signal converted by the optical sensor 3 is a modulated signal.

  The optical sensor 3 and the signal processing unit 7 are electrically connected by a cable 31. The cable 31 passes through the through hole of the magnet 11.

  The signal processing unit 7 is provided on the back surface of the speaker device. Specifically, the signal processing unit 7 is fixed to the yoke 14 of the magnetic circuit 1. In order not to disturb the vibration of the diaphragm 4, a vent hole 71 is provided between the magnetic circuit 1 and the yoke 14 to connect the inside and the outside of the speaker device. Since the air can freely move between the inside and outside of the speaker device by the vent hole 71, the vibration of the diaphragm 4 is not hindered.

  As shown in FIG. 3, the signal processing unit 7 includes, for example, a processing unit 72 and an amplifier 73. The electrical signal converted by the optical sensor 3 is input to the processing unit 72. The processing unit 72 generates an electrical signal to be given to the voice coil 8 based on the electrical signal. For example, when the electrical signal converted by the optical sensor 3 is a PCM format digital signal, the processing unit 72 provides an electrical signal for providing the voice coil 8 with an analog signal obtained by DA-converting the PCM format digital signal. Generate as a signal. When the electrical signal converted by the optical sensor 3 is a digital signal composed of a code sequence of acoustic signal encoding, the processing unit 72 obtains a PCM format digital signal by decoding the code sequence, An analog signal obtained by DA-converting a PCM format digital signal is generated as an electric signal to be applied to the voice coil 8. When the electrical signal converted by the optical sensor 3 is an analog signal, the processing unit 72 uses the electrical signal converted by the optical sensor 3 as it is as an electrical signal to be applied to the voice coil 8. When the electrical signal converted by the optical sensor 3 is a digitally modulated signal or an analog modulated signal, the processing unit 72 demodulates the electrical signal converted by the optical sensor 3 to generate a digital signal or an analog signal. After being obtained, it is generated as an electric signal to be given to the voice coil 8 in the same manner as the above digital signal or analog signal.

  The amplifier 73 amplifies the electric signal to be given to the voice coil 8 generated by the processing unit 72. The amplified electrical signal is applied to the voice coil 8.

  Since the voice coil 8 is disposed in the magnetic gap 15, it vibrates according to the applied electric signal. The vibration is transmitted to the voice coil bobbin 6, the center cap 5, and the diaphragm 4, and emits an acoustic signal. In this example, an acoustic signal is emitted in the left direction with respect to the paper surface of FIG.

  Thus, the speaker device can be simplified as compared with the conventional case by driving the speaker device with the electrical signal based on the optical signal received by the optical sensor 3 provided on the radiation surface side of the acoustic signal. In addition, by using an optical signal instead of an RF radio wave, the influence of electromagnetic interference caused by the magnet of the speaker is reduced, and the generation of noise is reduced as compared with the prior art.

[Second Embodiment]
With reference to FIG. 4, the speaker apparatus of 2nd embodiment is demonstrated. In order to abbreviate | omit duplication description, description about the part similar to 1st embodiment is abbreviate | omitted below, and it demonstrates centering on a different part from 1st embodiment.

  The speaker device of the second embodiment is provided with a plurality of optical sensors 3 as illustrated in FIG. In the example of FIG. 4, five optical sensors 3 are provided. In the speaker device of the second embodiment, an optical sensor 3 smaller than that of the speaker device of the first embodiment is used. Further, as the optical sensor 3, a sensor such as a CCD (Charge Coupled Device image sensor) may be used.

  The speaker device according to the second embodiment includes a lens that collects an optical signal received by the optical sensor 3. In the example of FIG. 4, the center cap 5 functions as a lens. The lens diffracts a plurality of different incident optical signals according to the incident position, and outputs them to the plurality of optical sensors 3, respectively. Each of the plurality of optical sensors 3 converts the input optical signal into an electrical signal. The center cap 5 as a lens can be made of acrylic, for example. For example, the lens is a Fresnel lens. In the second embodiment, the center cap 5 as a lens is a member different from the diaphragm 4, and is fixed to the frame 2 or the magnetic circuit 1 instead of the center of the diaphragm 4, and the optical sensor 3 is also the frame 2. Alternatively, it is fixed to the magnetic circuit 1 and the distance between the lens and the optical sensor 3 is not changed. In the example of FIG. 4, the center cap 5 as a lens is fixed to the magnetic circuit 1 via a cylindrical fixing member 51.

  The signal processing unit 7 performs parallel processing on a plurality of electrical signals converted by the plurality of optical sensors 3 to generate an electrical signal to be given to the voice coil 8. For example, as illustrated in FIG. 5, the processing unit 72 of the signal processing unit 7 includes a plurality of filters. In the example of FIG. 5, the processing unit 72 includes five filters 721, 722, 723, 724, and 725. The processing unit 72 demodulates each of the plurality of electrical signals converted by the plurality of optical sensors 3. In the demodulation, the filter 721 performs filter processing on the electrical signal caused by the first optical signal, the filter 722 performs filter processing on the electrical signal caused by the second optical signal, and the filter 723 performs the third light. The filter process is performed on the electrical signal caused by the signal, the filter 724 performs the filter process on the electrical signal caused by the fourth optical signal, and the filter 725 filters the electrical signal caused by the fifth optical signal. Process. The processing unit 72 synthesizes the electric signals that have undergone the filter processing and outputs them to the amplifier 73. Filtering here refers to, for example, changing the amplitude of an electrical signal resulting from an optical signal, changing the frequency characteristics of an electrical signal resulting from an optical signal, or applying a reverberation signal to an electrical signal resulting from an optical signal. It is a process to add.

  In this way, by performing different filter processing depending on the position where the optical signal is emitted, the speaker device can have light direction dependency, in other words, light directivity. When the position where the optical signal is emitted moves, signal processing using different filters can be performed according to the movement.

[Third embodiment]
With reference to FIG. 6, the speaker apparatus of 3rd embodiment is demonstrated. In order to abbreviate | omit duplication description, description about the part similar to 1st embodiment is abbreviate | omitted below, and it demonstrates centering on a different part from 1st embodiment.

  The speaker device of the third embodiment includes a lens that collects an optical signal received by the optical sensor 3. In the example of FIG. 6, the center cap 5 functions as a lens. The center cap 5 as a lens can be made of acrylic, for example. For example, the lens is a Fresnel lens. In the third embodiment, the lens is supported by the diaphragm 4 and the voice coil bobbin 6, and vibrates together with the diaphragm 4 and the voice coil bobbin 6. For this reason, when the optical sensor 3 is fixed to the frame 2 or the magnetic circuit 1, the distance between the lens and the optical sensor 3 changes according to the movement of the lens.

  The optical sensor 3 is disposed at a position where an optical signal transmitted through the lens can be received. When the input optical signal satisfies a predetermined condition, the optical sensor 3 is further disposed at the focal position of the lens. The predetermined condition is, for example, a condition that the intensity of the optical signal is a predetermined intensity such that no optical signal is input. The predetermined condition may be a condition that the intensity of the optical signal is the average intensity.

  FIG. 8 shows an equivalent circuit of the speaker device of the third embodiment. When the electrical signal converted by the optical sensor 3 is an analog signal, that is, when the processing unit 72 uses the electrical signal converted by the optical sensor 3 as it is as an electrical signal to be applied to the voice coil 8, As the strength increases, the strength of the electrical signal applied to the voice coil 8 also increases, and the center cap 5 as a lens moves greatly together with the voice coil bobbin 6 and the diaphragm 4. If it does so, the position of the optical sensor 3 will leave | separate from the position of the focus of a lens, and the intensity | strength of the optical signal which the optical sensor 3 receives will become small. Then, since the movement of the lens becomes smaller, the position of the optical sensor 3 approaches the focal position of the lens. Thus, feedback control is performed so that the position of the optical sensor 3 is in the vicinity of the focal position of the lens.

  By such feedback control, for example, even when the magnitude of the optical signal emitted to the speaker device of the third embodiment is constant, the optical signal received by the optical sensor 3 becomes a signal of a specific frequency. . As a result, since the electrical signal converted by the optical sensor 3 and the electrical signal to be applied to the voice coil 8 are signals having a specific frequency, the center cap 5 which is a lens has a specific frequency together with the voice coil bobbin 6 and the diaphragm 4. Vibrate. The frequency of the specific vibration depends on the electrical system properties, mechanical system properties, and optical system properties of the speaker device. The electrical system property of the speaker device is a property of the voice coil 8 or the like, and the mechanical system property of the speaker device is a property of the center cap 5, the voice coil bobbin 6, the diaphragm 4, or the like. The property is a property of the lens and the optical sensor 3.

  Therefore, if the signal processing in consideration of this feedback control is performed in the processing unit 72, or the optical signal generated by digital or analog modulation of the acoustic signal in consideration of this feedback control is applied to the speaker device of the third embodiment. In this case, a desired acoustic signal can be emitted by supporting the lens not by the non-vibrating frame 2 or the magnetic circuit 1 but by the vibrating diaphragm 4 or voice coil bobbin 6.

  For example, when the optical signal is an AM-modulated optical signal, the intensity of the optical signal received by the optical sensor 3 changes according to the distance between the lens and the optical sensor 3 as illustrated in FIG. Specifically, when the distance between the lens and the optical sensor 3 is the distance between the lens and the focal position of the lens, the intensity of the optical signal received by the optical sensor 3 is maximized, and the distance between the lens and the optical sensor 3 is The further away from the distance between the lens and the focal position of the lens, the lower the intensity of the optical signal received by the optical sensor 3. In this case, for example, the optical sensor 3 is in the vicinity of the focal position of the lens, and the change in the distance between the lens and the optical sensor 3 and the intensity of the optical signal received by the optical sensor 3 changes in a form close to linear. It may be arranged at a position (in FIG. 7, for example, a position R).

  It goes without saying that the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Magnetic circuit 11 Magnet 11a Through-hole 12, 13, 14 yoke 15 Magnetic space | gap 2 Frame 3 Optical sensor 31 Cable 4 Diaphragm 5 Center cap 6 Voice coil bobbin 7 Signal processing part 8 Voice coil 81, 82 Cable

Claims (8)

A speaker device for emitting an acoustic signal,
An optical sensor that is provided on the radiation surface side of the acoustic signal of the speaker device and converts the received optical signal into an electrical signal;
A signal processing unit for generating an electric signal to be given to the voice coil based on the electric signal;
A magnetic circuit fixed to the speaker frame and having a magnetic gap;
A voice coil disposed in the magnetic gap and provided with the electrical signal;
A diaphragm supported by the frame and vibrating with the voice coil to emit the acoustic signal;
Including speaker device. The speaker device according to claim 1,
Part or all of the diaphragm or part or all of the center cap attached to the diaphragm is made of a light-transmitting material.
The optical sensor is disposed at a position where the optical signal transmitted through the diaphragm or the portion made of the light-transmitting material of the center cap can be received.
Speaker device. The speaker device according to claim 1,
The optical sensor is one or a plurality of optical sensors,
A lens for collecting an optical signal received by the optical sensor;
Speaker device. The speaker device according to claim 3, wherein
The optical sensor is a plurality of optical sensors,
Each of the plurality of optical sensors is disposed at a position where different optical signals transmitted through the lens can be received.
Speaker device. The speaker device according to claim 3, wherein
The optical sensor is a single optical sensor,
The optical sensor and the lens are fixed to the frame,
The optical sensor is a position where an optical signal transmitted through the lens can be received, and is disposed at a focal position of the lens.
Speaker device. The speaker device according to claim 3, wherein
The optical sensor is a single optical sensor,
The optical sensor is fixed to the frame,
The lens is supported by the diaphragm,
The optical sensor is disposed at a position where the optical signal transmitted through the lens can be received, and is further disposed at the focal position of the lens when the input optical signal satisfies a predetermined condition.
Speaker device. The speaker device according to any one of claims 1 to 5,
The magnetic circuit includes a magnet having a through hole, and a cable connecting the optical sensor and the signal processing unit passes through the through hole.
Speaker device. The speaker device according to any one of claims 1 to 5,
The cable that electrically connects the voice coil and the signal processing unit is disposed at a position that does not interfere with the optical signal received by the optical sensor.
Speaker device.

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