JP2003087892A - Speaker, speaker system, and speaker control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a speaker system or the like with high linearity. SOLUTION: The speaker system 1 comprises an amplifier section 20, a speaker section 30 and a feedback circuit 40. The speaker section 30 drives its diaphragm in response to a drive signal received from the amplifier section 20. A light emitting element and a light receiving circuit to optically detect the displacement of the diaphragm are placed in the speaker section 30. The light receiving circuit detects a change in the position of the diaphragm from an emitted position of a reflected light from the light emitting element via a cap fixed to the diaphragm and converts the change into an electric signal to provide an output of the signal to the feedback circuit 40. The feedback circuit 40 generates an error signal on the basis of the electric signal and feeds it back to the amplifier section 20. The amplifier section 20 amplifies a signal corresponding to a difference between the input signal from a signal source 10 and the feedback signal from the feedback circuit 40 and supplies the amplified signal to the speaker section 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a speaker, a speaker system and a speaker control method.

[0002]

2. Description of the Related Art Recently, CDs (Compact Disks), MDs (Mini Ds) that record music information by digital recording methods such as MP3, etc.
2. Description of the Related Art Digital AV (Audio Visual) speaker systems that use a recording medium such as isk), a DVD (Digital Versatile Disk), or a received radio wave such as digital TV broadcast as a signal source are in widespread use.

Conventionally, in a general-purpose speaker system, a correction circuit (feedback circuit) as shown in FIG. 10 is used in order to ensure linearity between an input signal to the system and an output signal of the system. To do. That is, the amplifier unit 1
A part of the output signal of 02 is inverted and input to the amplifier unit 102 via the feedback circuit 104. This makes it possible to compensate (correct) the non-linear distortion caused mainly by the non-linearity of the amplification characteristic of the amplifier section 102.

As shown in FIG. 11, the speaker unit 1
There is known a speaker system in which a microphone 105 is arranged on the output side of 03. In this speaker system, the microphone 105 detects the audio output of the speaker unit 103, converts it into an electric signal, and feeds it back to the amplifier unit 102 via the feedback circuit 104.

[0005]

In the above-mentioned conventional technique, according to the speaker system using the correction circuit as shown in FIG. 10, for example, the speaker unit 103 such as the natural vibration of the diaphragm, the viscosity of the movable part, and the magnetic distortion. The non-linear distortion due to can not be corrected. Therefore, it cannot be applied to a digital AV speaker system that requires higher accuracy linearity than a general-purpose speaker system.

Further, in the speaker system as shown in FIG. 11, the microphone 105 detects not only the sound output of the speaker unit 103 but also the noise generated in the placed environment. Further, the input / output characteristic of the microphone 105 also has nonlinearity. That is, the signal input to the feedback circuit 104 includes a component other than the nonlinearity of the amplifier unit 102 and the speaker unit 103. Therefore, it is difficult to ensure the linearity between the input signal from the signal source 101 and the output of the speaker unit 103 (as the entire system) with high accuracy.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a speaker system and the like which can obtain high linearity.

[0008]

In order to achieve the above object, a speaker according to a first aspect of the present invention is provided with a light emitting means for emitting a light beam and a speaker vibration provided near a central portion of a speaker diaphragm. Reflecting means that vibrates with the plate and reflects the light from the light emitting means, and light receiving that detects the light reflected by the reflecting means and converts it into an electric signal having a voltage corresponding to the position of the speaker diaphragm. And means.

The light receiving means is installed in a direction orthogonal to the vibration displacement direction of the speaker diaphragm, and a DC voltage source having one end grounded and the other end connected to one end of the reference resistor. A plurality of photodetectors, and a plurality of resistors provided corresponding to each of the photodetectors, each resistor is connected in series in the order corresponding to the installation position of each photodetector. , The resistor provided at one end is grounded, and the resistor provided at the other end is connected to one end where the DC voltage source is not connected by the reference resistor, and is connected in series. It is desirable to output a connection point voltage between the plurality of resistors and the reference resistor.

It is desirable that the light emitting means and the light receiving means be held by a member forming a magnetic circuit for driving the speaker diaphragm.

A speaker system according to a second aspect of the present invention is a drive signal generating means for generating a drive signal for driving a diaphragm of a speaker in response to a signal from a signal source, and the drive signal generating means. Diaphragm drive means for driving the diaphragm of the speaker in response to the drive signal generated by the means,
A light emitting means for emitting a light beam for detecting the position of the speaker driven by the diaphragm driving means; a reflecting means for vibrating together with the diaphragm of the speaker to reflect the light from the light emitting means; Light receiving means for detecting the light reflected by the means and converting it into an electric signal having a voltage corresponding to the position of the diaphragm; and the drive signal generating means based on the electric signal generated by the light receiving means. Correction signal generating means for generating a signal for correcting the drive signal generated by and supplying the signal to the drive signal generating means.

The light receiving means is provided with a reference resistor, one end of which is grounded and the other end of which is connected to one end of the reference resistor, and a DC voltage source which is orthogonal to the vibration displacement direction of the speaker diaphragm. A plurality of photodetectors, and a plurality of resistors provided corresponding to each of the photodetectors, each resistor is connected in series in the order corresponding to the installation position of each photodetector. , The resistor provided at one end is grounded, and the resistor provided at the other end is connected to one end where the DC voltage source is not connected by the reference resistor, and is connected in series. It is desirable to output the connection point voltage between the plurality of resistors and the reference resistor, to the correction signal generating means.

Alternatively, the light receiving means may generate an electric signal having a voltage having a magnitude corresponding to the amount of light incident within a predetermined area, and output the electric signal to the correction signal generating means.

A speaker control method according to a third aspect of the present invention comprises a drive signal generating step for generating a drive signal for driving a diaphragm of a speaker in response to a signal from a signal source, and the drive signal. A diaphragm driving step of driving the diaphragm of the speaker by the driving signal generated in the generating step; a light emitting step of emitting a light beam for detecting the position of the speaker driven in the diaphragm driving step; With the reflector that vibrates with the diaphragm of
A reflecting step of reflecting the light beam emitted in the light emitting step, and a light receiving step of detecting the light reflected in the reflecting step and converting the light into an electric signal having a voltage corresponding to the position of the diaphragm. And a correction signal generating step of generating a signal for correcting the drive signal generated in the drive signal generating step based on the electric signal generated in the light receiving step.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION A speaker system and the like according to embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows the overall structure of a speaker system 1 according to an embodiment of the present invention. As shown in FIG. 1, the speaker system 1 is for outputting sound in response to an input signal from the signal source 10, and includes an amplifier unit 20 and
It is composed of a speaker unit 30 and a feedback circuit 40.

The amplifier section 20 comprises a subtraction circuit, a power amplifier and the like. The amplifier section 20 receives the input signal from the signal source 10 at the non-inverting input terminal and the feedback signal from the feedback circuit 40 at the inverting input terminal. The amplifier section 20 is
A signal corresponding to the difference between the input signal from the signal source 10 and the feedback signal from the feedback circuit 40 is amplified and supplied to the speaker unit 30.

The speaker section 30 is for converting an electric signal into mechanical vibration and outputting a sound. For example, as shown in FIG. 2, a frame 31, a diaphragm 32, a damper 33, and a magnet. 34, a center pole 35, a cap 36, a voice coil 37, a light emitting element 38, and a light receiving circuit 39.

The vibrating plate 32 is formed into a substantially conical shape (cone shape) by using, for example, paper or the like, and is for generating air vibration and emitting sound waves. The vibrating plate 32 has a peripheral edge portion supported by the frame 31 via an edge member or the like. Further, the diaphragm 32 has a hole in the center, and a cap 36 is fitted and attached.

The damper 33 is for holding the cap 36, around which the voice coil 37 is wound, on the frame 31 in a freely vibrating manner.

The magnet 34 is an annular driving magnet, and is for driving the diaphragm 32 by an electromagnetic force acting between the magnet 34 and the voice coil 37.

The center pole 35 is made of, for example, a ferromagnetic material, and forms a magnetic circuit together with the magnet 34 to generate an electromagnetic force between the center pole 35 and the voice coil 37. Here, the center pole 35 is a cap 36.
Is adjusted coaxially with and holds the light emitting element 38 and the light receiving circuit 39 at predetermined positions.

The cap 36 is fitted in a hole provided in the center of the diaphragm 32, and the voice coil 37 is wound around the side wall thereof. The inner surface of the cap 36 is, for example, mirror-finished to be formed into a substantially hemispherical shape, and reflects the light beam emitted by the light emitting element 38 without attenuating and scattering.

Both ends of the voice coil 37 are connected to the amplifier section 20, and the electromagnetic force generated by the magnetic field in the gap provided between the magnet 34 and the center pole 35 and the current supplied from the amplifier section 20 is applied. The vibration plate 32, to which the cap 36 is fixed, is set in the vibration displacement direction x
Drive in the direction to emit sound waves.

The light emitting element 38 is, for example, an LED (Light Em
itting diode) or a laser emitter,
Light of a predetermined wavelength is emitted to irradiate the inner surface of the cap 36.

The light receiving circuit 39 is for receiving the reflected light reflected by the inner surface of the cap 36. Figure 3
FIG. 6 is a diagram showing an example of a configuration of a light receiving circuit 39.

As shown in FIG. 3, the light receiving circuit 39 is, for example,
DC voltage source V_DDAnd the reference resistor R₀And multiple lights
Detector Q₁~ Q_n(N is an arbitrary natural number) and resistor R₁
~ R _nAnd is configured.

The DC voltage source V _DD has, for example, a negative electrode grounded and a positive electrode connected to one end of the reference resistor R ₀ . Each of the photodetectors Q _{1 to} Q _n is composed of, for example, a phototransistor whose emitter is grounded, and is arranged so as to be aligned in the x ′ direction orthogonal to the x direction which is the vibration displacement direction of the diaphragm 32. Each of the resistors R _{1 to} R _n corresponds to each of the photodetectors Q ₁
It provided corresponding to to Q _n, are connected in series in the order corresponding to the installation position of each photodetector Q ₁ to Q _n. That is,
One end of the resistor R _k (k: 1 to n−1) is the resistor R
_k-1 and the other end is connected to the resistor R _{k + 1} . At the connection point between the resistor R _k and the resistor R _k-1 , for example, a photodetector Q _k, which is a phototransistor, is provided.
The collector of is connected. Here, one end of the resistor R ₁ is connected to one end of the reference resistor R _{0 to which the} DC voltage source V _DD is not connected. The voltage at the connection point between the resistor R ₁ and the reference resistor R ₀ is supplied to the feedback circuit 40 as the output voltage V _out . Further, one end of the resistor R _{n to which the} resistor R _n-1 is not connected is grounded.

Returning to FIG. 1, the feedback circuit 40 comprises an amplifier for amplifying the output signal of the light receiving circuit 39 with a predetermined loop gain, and the amplifier section 20 and the speaker section 30.
This is for generating an error signal corresponding to the magnitude of non-linear distortion due to and feeding back to the amplifier section 20. For example, the feedback circuit 40 obtains the ideal response of the speaker unit 30 to the input signal from the signal source 10, and also obtains the actual response of the speaker unit 30 from the one in which the phase of the output signal of the light receiving circuit 39 is inverted. Identify. The feedback circuit 40 amplifies an error between the ideal response and the actual response of the speaker unit 30 to generate an error signal having a voltage corresponding to the magnitude of nonlinear distortion.

The operation of the speaker system 1 having the above configuration will be described below. In the speaker system 1, the light receiving circuit 39 detects the light emitted from the light emitting element 38 to the inner surface of the cap 36, and thereby the nonlinear distortion due to the amplifier section 20 and the speaker section 30 can be specified and compensated (corrected). System.

The amplifier section 20 amplifies an input signal sent from a predetermined signal source 10, and the like, so that the speaker section 3
A signal for driving 0 is generated and supplied to the speaker unit 30.

When the input signal amplified by the amplifier section 20 is supplied to the speaker section 30, the electromagnetic force acting on the voice coil 37 drives the diaphragm 32 in the x direction, which is the vibration displacement direction, and outputs a sound. . At this time, the position of the cap 36 fitted in the central portion of the diaphragm 32 also changes with the diaphragm 32.

The light emitted from the light emitting element 38 is emitted by the cap 36.
The light is reflected by the inner surface of the irradiator and is irradiated to the light receiving circuit 39, and the vibration plate 3
An output voltage V _out corresponding to the 2 position is generated. The signal having the output voltage V _out generated by the light receiving circuit 39 is supplied to the feedback circuit 40.

Here, as shown in FIG.
Has a substantially hemispherical inner surface, for example, and the irradiation position of the reflected light in the light receiving circuit 39 moves with the movement in the x direction. Accordingly, in the light receiving circuit 39, the vibration of the cap 36 in the x direction is detected as the vibration of the irradiation position of the reflected light in the x ′ direction.

When the irradiation position of the reflected light is moved, one of the plurality of photodetectors Q _{1 to} Q _n which is conducting is switched,
The output voltage V _out from the light receiving circuit 39 changes. For example, as shown in FIG. 4, when the diaphragm 32 is at the rearmost position A ₁ in the x direction, which is the vibration displacement direction, the light reflected by the inner surface of the cap 36 irradiates the photodetector Q ₁ . To be done. Further, when the diaphragm 32 is at the position A ₂ which is the most forward in the x direction, the light reflected by the inner surface of the cap 36 is applied to the photodetector Q _n .

When the photodetector Q ₁ is irradiated with the reflected light, the photodetector Q ₁ becomes conductive, so that the resistor R ₁ and the reference resistor R ₁ are connected.
The connection point with ₀ is almost grounded. On the other hand, the light reflected to the photodetector _{Q n} is irradiated, the light detector _{Q n} is conductive, the output voltage _{V out} is the reference resistor _{R 0,} series-connected resistors _R 1 to R _{n -1} and DC voltage source V
It is almost equal to the divided voltage of _DD . In this way, the light receiving circuit 39 generates an electric signal having a voltage having a magnitude corresponding to the position of the diaphragm 32, and the feedback circuit 4
Supply to 0.

Here, the shape of the inner surface of the cap 36 that reflects the light from the light emitting element 38, the installation positions of the photodetectors Q _{1 to} Q _n , the reference resistor R ₀ and the resistors R _{1 to} R _n . By appropriately setting the resistance value and the like, a displacement amount by which the irradiation position of the reflected light in the light receiving circuit 39 moves in the x ′ direction,
The relationship with the output voltage V _out of the light receiving circuit 39 can be a relationship having negative linearity as shown in FIG. 5, for example. As a result, the output of the speaker unit 30 (the diaphragm 32
Position) and the output voltage V _out of the light receiving circuit 39,
It is possible to secure the linearity and detect the non-linear distortion generated in the amplifier section 20 and the speaker section 30.

The feedback circuit 40 receiving the signal from the light receiving circuit 39 generates an error signal corresponding to the magnitude of the non-linear distortion by amplifying the signal with a predetermined amplification factor, and feeds it back to the amplifier section 20. . The amplifier unit 20 corrects the signal supplied to the speaker unit 30 by taking the difference between the error signal received from the feedback circuit 40 and the input signal from the signal source 10. Accordingly, the non-linear distortion generated in the amplifier section 20 and the speaker section 30 can be appropriately detected and corrected, and high linearity can be obtained.

As described above, according to the embodiment of the present invention, the output of the speaker unit 30 (position of the diaphragm 32).
Is detected using the light emitting element 38 and the light receiving circuit 39.
The detection result, that is, the output voltage of the light receiving circuit 39 and the output of the speaker unit 30 have a good linearity. The feedback circuit 40 uses the output signal from the light receiving circuit 39 to specify the error signal indicating the magnitude of the non-linear distortion, and the amplifier unit 20.
Supply to. The amplifier unit 20 corrects the signal supplied to the speaker unit 30 based on the error signal received from the feedback circuit 40, and thereby the linearity between the input signal from the signal source 10 and the output of the speaker unit 30 is It is possible to ensure the accuracy. Since the non-linear distortion is detected by light, the noise generated in the arranged environment is not detected.

The light emitting element 38 and the light receiving circuit 39 are
Since both are held by the center pole 35, the weight of the vibration system (for example, the diaphragm 32, the cap 36, etc.) for emitting sound waves in the speaker unit 30 does not increase. Therefore, the magnitude of the non-linear distortion can be detected without deteriorating the characteristics of the speaker unit 30.

In the above embodiment, the diaphragm 32 is detected by detecting the irradiation position of the reflected light in the light receiving circuit 39.
However, the position of the diaphragm 32 may be detected based on the intensity of reflected light, for example. Hereinafter, a modified example of the speaker system 1 that detects the position of the diaphragm 32 from the intensity of reflected light will be described.

For example, instead of the light emitting element 38 and the light receiving circuit 39 shown in FIG. 2, a light emitting and receiving element 51 is arranged at the center of the center pole 35. The light emitting / receiving element 51 is, for example,
It has a cylindrical outer shape, and a light receiving element is arranged in the central portion and a light emitting element is arranged in the outer peripheral portion.

As shown in FIG. 6, when the vibration plate 32 moves (vibrates) in the x direction, which is the vibration displacement direction, in accordance with the signal supplied from the amplifier unit 20 to the speaker unit 30, the vibration plate 32 is fitted into the central portion of the vibration plate 32. The position of the combined cap 36 also changes. In this modification, even if the cap 36 vibrates in the x direction, the light receiving element of the light emitting and receiving element 51 detects the reflected light at a fixed position.

Here, the inner surface of the cap 36 has a shape for diffusing the light emitted by the light emitting element of the light emitting and receiving element 51. Therefore, the irradiation area of the reflected light with which the light receiving element of the light emitting and receiving element 51 is irradiated increases or decreases as the cap 36, that is, the diaphragm 32 moves in the x direction, as shown in FIG. Therefore, the amount of reflected light incident on the light receiving element provided in the central portion of the light emitting / receiving element 51 and having a predetermined light receiving area changes corresponding to the position of the cap 36.

Therefore, as the light receiving element of the light emitting and receiving element 51, as shown in FIG. 8, a light receiving circuit in which a photodetector Q _{1 including} a phototransistor and a resistor R are connected in series is provided. Thus, as shown in FIG. 9, the output voltage V _{ou t} of the light-emitting light-receiving element 51, with respect to the radius x 'of the reflected light spot on the light receiving surface of the light-emitting light-receiving element 51 has a positive linearity .

In this case, the feedback circuit 40 receives the output voltage V _out as the output signal of the speaker unit 30, amplifies the phase without inverting the phase of the output signal, generates an error signal, and inverts the amplifier unit 20. Supply it to the input terminal and feed it back. The components other than those described here and the operation thereof are the same as those described in the above embodiment.

As described above, according to this modification, the output of the speaker unit 30 (position of the diaphragm 32) can be detected by a simpler light receiving circuit as compared with the above embodiment. Also, the output voltage V _out of the light receiving circuit
Has a positive linearity with respect to the position of the diaphragm 32,
The feedback circuit 40 does not need to invert the phase of the output signal from the light receiving circuit, and can detect the non-linear distortion with a simpler configuration.

The present invention is not limited to the above embodiment,
Various modifications and applications are possible. For example, although the photodetectors Q _{1 to} Q _n have been described as phototransistors in the above embodiments, they may be other photodetection devices such as photodiodes.

In the above embodiment, the inner surface of the cap 36 fitted in the hole provided in the central portion of the diaphragm 32 is
Although it is described that the light emitted from the light emitting element 38 is reflected, the invention is not limited to this. That is, the light emitted from the light emitting element 38 is reflected by providing a mirror-finished portion at a location where the position of the diaphragm 32 is easily detected, such as near the center of the diaphragm 32. May be.

[0050]

According to the present invention, it is possible to provide a speaker system or the like which can obtain high linearity.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of a speaker system according to an embodiment of the present invention.

FIG. 2 is a sectional view showing a schematic structure of a speaker unit according to an embodiment of the present invention.

FIG. 3 is a diagram showing an example of a configuration of a light receiving circuit according to an embodiment of the present invention.

FIG. 4 is a diagram for explaining a principle of detecting light accompanying vibration of a diaphragm.

FIG. 5 is a diagram showing a relationship between an irradiation position of reflected light and an output voltage of a light receiving circuit.

FIG. 6 is a diagram for explaining a principle of detecting light accompanying vibration of a diaphragm in a light emitting and receiving element according to a modification of the present invention.

FIG. 7 is a diagram showing a change in irradiation area of light received by a light emitting and receiving element according to a modification of the present invention.

FIG. 8 is a diagram showing an example of a configuration of a light emitting / receiving element according to a modification of the present invention.

FIG. 9 is a diagram showing a relationship between a radius of a reflected light spot and an output voltage of a light emitting / receiving element.

FIG. 10 is a block diagram showing a configuration example of a conventional speaker system.

FIG. 11 is a block diagram showing another configuration example of a conventional speaker system.

[Explanation of symbols]

1 speaker system 10 signal source 20 Amplifier section 30 speaker 31 frames 32 diaphragm 33 damper 34 Magnet 35 center pole 36 cap 37 voice coils 38 light emitting device 39 Light receiving circuit

Claims (7)

[Claims] 1. A light emitting means for emitting a light beam, a reflecting means provided near a central portion of the speaker diaphragm for vibrating together with the speaker diaphragm and reflecting light from the light emitting means, and a reflecting means for reflecting the light from the light emitting means. And a light receiving unit that detects the emitted light and converts it into an electric signal having a voltage of a magnitude corresponding to the position of the speaker diaphragm. 2. The light receiving means includes a reference resistor, a DC voltage source having one end grounded and the other end connected to one end of the reference resistor, and a direction orthogonal to the vibration displacement direction of the speaker diaphragm. A plurality of photodetectors installed in the, and a plurality of resistors provided corresponding to each of the photodetectors, each resistor in series in the order corresponding to the installation position of each photodetector Connected, the resistor provided at one end is grounded, the resistor provided at the other end is connected to one end where the DC voltage source is not connected in the reference resistor, A speaker that outputs a connection point voltage between the plurality of resistors connected in series and the reference resistor. 3. The speaker according to claim 1, wherein the light emitting means and the light receiving means are held by a member forming a magnetic circuit for driving the speaker diaphragm. 4. A drive signal generating means for generating a drive signal for driving a diaphragm of a speaker in response to a signal from a signal source, and a speaker receiving the drive signal generated by the drive signal generating means. Diaphragm driving means for driving the diaphragm, the light emitting means for emitting a light beam for detecting the position of the speaker driven by the diaphragm driving means, and the light emitting means for vibrating together with the diaphragm of the speaker. Generated by the light receiving means, and a light receiving means for detecting the light reflected by the reflecting means and converting it into an electric signal having a voltage of a magnitude corresponding to the position of the diaphragm. Correction signal generating means for generating a signal for correcting the drive signal generated by the drive signal generating means based on the electric signal and supplying the signal to the drive signal generating means. Speaker system according to claim. 5. The light receiving means includes a reference resistor, a DC voltage source having one end grounded and the other end connected to one end of the reference resistor, and a direction orthogonal to the vibration displacement direction of the speaker diaphragm. A plurality of photodetectors installed in the, and a plurality of resistors provided corresponding to each of the photodetectors, each resistor in series in the order corresponding to the installation position of each photodetector Connected, the resistor provided at one end is grounded, the resistor provided at the other end is connected to one end where the DC voltage source is not connected in the reference resistor, The speaker system according to claim 4, wherein the connection point voltage between the plurality of resistors connected in series and the reference resistor is output to the correction signal generating means. 6. The light receiving means generates an electric signal having a voltage corresponding to an amount of light incident within a predetermined area and outputs the electric signal to the correction signal generating means. The speaker system according to. 7. A drive signal generation step for generating a drive signal for driving a diaphragm of a speaker in response to a signal from a signal source, and a vibration of the speaker by the drive signal generated in the drive signal generation step. A diaphragm driving step of driving the plate; a light emitting step of emitting a light beam for detecting the position of the speaker driven in the diaphragm driving step; and a reflecting portion vibrating together with the speaker diaphragm to emit the light. A reflecting step of reflecting the light beam emitted in the step, a light receiving step of detecting the light reflected in the reflecting step, and converting into an electric signal having a voltage of a magnitude corresponding to the position of the diaphragm, A signal for correcting the drive signal generated in the drive signal generating step is generated based on the electric signal generated in the light receiving step. And a positive signal generating step, a speaker control method characterized by.