JP2009232346A - Sound output system and audio amplifier used for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform connection drive of both a plane speaker and another electrodynamic speaker. <P>SOLUTION: A sound output system comprises: a pulsewidth modulation section 6 for performing pulsewidth modulation upon an input signal on the basis of a reference clock; a first edge trigger section 8a for frequency-dividing the reference clock; a second edge trigger section 8b for frequency-dividing a modulation signal; a phase inverting section 9 for phase-inverting the modulation signal; a first switch SW1 for switching and supplying to first and second switching elements 13a and 13b the frequency-divided reference clock and the phase-inverted modulation signal; a second switch SW2 for switching and supplying to third and fourth switching elements 13c and 13d the frequency-divided modulation signal and the modulated modulation signal; a third switch SW3 for switching whether to supply driving currents from the first and second switching elements 13a and 13b to a plane speaker 1 or to an electrodynamic speaker 2; and a fourth switch SW4 for switching whether to supply driving currents from the third and fourth switching elements 13c and 13d to the plane speaker 1 or to the electrodynamic speaker 2. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an audio output system for outputting audio from a flat speaker, another electrodynamic speaker having a different driving form from the flat speaker, and an audio amplifier used in the audio output system.

  2. Description of the Related Art Conventionally, a speaker as an audio device has, for example, a substantially conical diaphragm, and the diaphragm vibrates by outputting a drive current to a voice coil provided in the diaphragm, and outputs a sound. There are electric speakers.

  As an audio amplifier for driving this electrodynamic speaker, for example, a switching amplifier that performs pulse width modulation on the original audio signal is known. In this switching amplifier, switching elements such as MOS-FETs are alternately turned on and off by a modulation signal obtained by modulating an audio signal and an inverted modulation signal obtained by inverting the modulation signal, and harmonic components are removed by a low-pass filter. Then, the drive current is supplied to the electrodynamic speaker.

  On the other hand, in recent years, for example, a pair of plane plates arranged opposite to each other is provided, and the plane plates are vibrated based on electromagnetic force generated by the direction of the drive current flowing in the conductor lines formed on the pair of plane plates. Has been proposed (see, for example, Patent Document 1).

Japanese Patent No. 3349647

  The present applicant has proposed a speaker system including the above planar speaker and a switching amplifier for driving it in Japanese Patent Application No. 2006-284478. 9 and 10 are diagrams showing a schematic structural diagram of a planar speaker and pulse signals (control pulse signal and driving pulse signal) for driving the planar speaker.

  According to these drawings, the flat speaker has a pair of diaphragms 21a and 21b formed with conductor lines 22a and 22b, for example, and the conductor lines 22a and 22b have a high level and a low level at a constant period. By supplying a control pulse signal that repeats alternately and a drive pulse signal whose duty ratio changes according to the amplitude of the audio signal, an attractive force and a repulsive force are generated between the pair of diaphragms 21a and 21b.

  FIG. 9 is a diagram illustrating a case where repulsive force is generated between the pair of diaphragms 21a and 21b. When the control pulse signal and the drive pulse signal are at different levels (see the shaded area), one diaphragm 21a is illustrated. The directions of the current flowing in the conductor line 22a and the current flowing in the conductor line 22b of the other diaphragm 21b are opposite to each other, and a repulsive force is generated between the pair of diaphragms 21a and 21b.

  On the other hand, FIG. 10 is a diagram showing a case where an attractive force is generated between the pair of diaphragms 21a and 21b. When the control pulse signal and the drive pulse signal are at the same level (see the shaded portion), The direction of the current flowing through the conductor line 22a of the diaphragm 21a and the current flowing through the conductor line 22b of the other diaphragm 21b are the same direction, and an attractive force is generated between the pair of diaphragms 21a and 21b. In this way, when a repulsive force and an attractive force are generated between the pair of diaphragms 21a and 21b, one of the pair of diaphragms 21a and 21b vibrates, thereby outputting a sound.

  As described above, when driving a planar speaker, it is necessary to supply a driving signal different from, for example, an electrodynamic speaker driven by a driving current based on a modulation signal and an inverted modulation signal to the planar speaker. . Therefore, an audio amplifier (switching amplifier) that connects and drives a planar speaker has a circuit unique to the planar speaker, and is unique to the planar speaker.

  Therefore, for example, when a user wants to output a sound from the speaker by connecting an electrodynamic speaker to the audio amplifier instead of a flat speaker, the audio amplifier generates a drive signal for driving the electrodynamic speaker. Therefore, there is a problem that an electrodynamic speaker cannot be connected and driven.

  In particular, although proposals related to planar speakers have been made in recent years, the demand is still lower than that of electrodynamic speakers, etc., so audio amplifiers that can drive planar speakers are used in electrodynamic speakers, etc. There is a request to connect a conventional speaker.

  The present invention has been conceived under the circumstances described above, and provides an audio output system capable of connecting and driving both a planar speaker and another speaker having a different driving form. Is the issue. It is another object of the present invention to provide an audio amplifier used in this audio output system.

  In order to solve the above problems, the present invention takes the following technical means.

  The audio output system provided by the first aspect of the present invention can be connected to a signal source that generates an audio signal as an input signal, and generates a reference clock and a reference from the clock generation unit Pulse width modulation means for pulse-modulating an input signal from the signal source based on a clock and outputting a modulated signal; clock frequency dividing means for dividing a reference clock from the clock generation means; and the pulse width modulation Modulation signal dividing means for dividing the modulation signal from the means, phase inversion means for inverting the phase of the modulation signal from the pulse width modulation means, and switching between positive and negative power supply voltages based on the level of the supplied signal First current supply means for supplying the drive current to the subsequent stage, and switching between positive and negative power supply voltages based on the level of the supplied signal The second current supply means provided separately from the first current supply means, which is supplied to the subsequent stage as a dynamic current, the reference clock divided by the clock frequency divider, and the phase inverted by the phase inverter. A first switching means for switching the modulated signal to be supplied to the first current supply means, a modulation signal that is frequency-divided by the modulation signal dividing means in conjunction with the first switching means, A second switching means for switching the modulation signal modulated by the pulse width modulation means to supply the second current supply means; and a pair of opposed flat plates, each surface of the pair of flat plates Based on the electromagnetic force (also referred to as current force, the same applies hereinafter) generated by the direction of the current flowing in the formed conductor line, one or both of the pair of plane plates is vibrated to generate sound. A planar speaker for output, and another electrodynamic speaker for outputting sound by supplying a driving current based on the modulation signal from the pulse width modulation means and the modulation signal phase-inverted by the phase inversion means; In conjunction with the first switching means, it is switched whether the drive current from the first current supply means is supplied to one end of the planar speaker or one end of the other electrodynamic speaker. In conjunction with the third switching means and the first switching means, the drive current from the second current supply means is supplied to the other end of the planar speaker or the other of the other electrodynamic speakers And a fourth switching means for switching whether to supply to the end (Claim 1).

  According to this configuration, when the first to fourth switching means are switched to one side (for example, the flat speaker side), the reference clock divided by the clock frequency dividing means by the first switching means is the first. Is supplied to the current supply means, and the second switching means supplies the modulation signal divided by the modulation signal dividing means to the second current supply means. In the first current supply means, positive and negative power supply voltages are switched based on the level of the supplied divided reference clock, and supplied as one drive current to one end of the planar speaker via the third switching means. The In the second current supply means, positive and negative power supply voltages are switched based on the level of the frequency-divided modulation signal supplied and supplied as the drive current to the other end of the flat speaker via the fourth switching means. The

  On the other hand, when the first to fourth switching means are switched to the other side (for example, another electrodynamic speaker side), the modulated signal whose phase is inverted by the phase switching means by the first switching means is the first current. In addition to being supplied to the supply means, the second switching means supplies the modulation signal modulated by the pulse width modulation means to the second current supply means. In the first current supply means, positive and negative power supply voltages are switched based on the level of the phase-inverted modulation signal to be supplied, and one end of another electrodynamic speaker as a drive current via the third switching means. To be supplied. In the second current supply means, the positive and negative power supply voltages are switched based on the level of the supplied modulation signal and supplied as the drive current to the other end of the other electrodynamic speaker via the fourth switching means. .

  Thus, in the audio output system, a planar speaker and another electrodynamic speaker can be connected together, and the planar speaker and the other electrodynamic speaker can be connected by the first to fourth switching means. Can be easily switched and driven. Therefore, it is not necessary to separately prepare an amplifier device dedicated to a planar speaker or another amplifier device dedicated to an electrodynamic speaker, and a versatile audio output system can be provided.

  In the audio output system of the present invention, a harmonic component of one output of the third switching means is removed between one output end of the third switching means and the other electrodynamic speaker. A first filter means is interposed between the one output end of the fourth switching means and the other electrodynamic loudspeaker to remove harmonic components of one output of the fourth switching means. The second filter means may be interposed (claim 2).

  The audio output system provided by the second aspect of the present invention can be connected to a signal source that generates an audio signal as an input signal, and generates a reference clock, and a reference from the clock generation unit Pulse width modulation means for pulse-modulating an input signal from the signal source based on a clock and outputting a modulated signal; clock frequency dividing means for dividing a reference clock from the clock generation means; and the pulse width modulation A modulation signal dividing means for dividing the modulation signal from the means, a phase inversion means for phase-inverting the modulation signal from the pulse width modulation means, and a pair of opposed plane plates, Based on the electromagnetic force generated by the direction of the current flowing in the conductor line formed on each surface, either one or both of the plane plates A planar speaker that outputs sound by being moved, and a positive / negative power supply voltage is switched based on the level of the reference clock frequency-divided by the clock frequency dividing means and supplied to one end of the planar speaker as a drive current A first current supply means and a second current supply means for switching the positive and negative power supply voltage based on the level of the modulation signal divided by the modulation signal dividing means to supply the drive current to the other end of the planar speaker. Current supply means, another electrodynamic loudspeaker that outputs sound when supplied with a drive current based on the modulation signal from the pulse width modulation means and the modulation signal phase-inverted by the phase inversion means, and the pulse The positive and negative power supply voltages are switched based on the level of the modulation signal modulated by the width modulation means, and the other electrodynamic type switches are used as drive currents. Third current supply means for supplying to one end of the speaker, and the other electrodynamic speaker as a drive current by switching positive and negative power supply voltages based on the level of the modulation signal phase-inverted by the phase inversion means And a fourth current supply means for supplying the other end of the first current supply means.

  The audio amplifier provided by the third aspect of the present invention can be connected to a signal source that generates an audio signal as an input signal, and generates a reference clock, and a reference clock from the clock generation means A pulse width modulation means for pulse-modulating an input signal from the signal source and outputting a modulated signal, a clock frequency dividing means for dividing a reference clock from the clock generation means, and the pulse width modulation means Modulation signal dividing means for dividing the modulation signal from the signal, phase inversion means for inverting the phase of the modulation signal from the pulse width modulation means, and switching between positive and negative power supply voltages based on the level of the supplied signal First current supply means for supplying the drive current to the subsequent stage, and switching between positive and negative power supply voltages based on the level of the supplied signal The second current supply means provided separately from the first current supply means, which is supplied to the subsequent stage as a dynamic current, the reference clock divided by the clock frequency divider, and the phase inverted by the phase inverter. A first switching means for switching the modulated signal to be supplied to the first current supply means, a modulation signal that is frequency-divided by the modulation signal dividing means in conjunction with the first switching means, A second switching unit that switches the modulation signal modulated by the pulse width modulation unit and supplies the modulated signal to the second current supply unit; and, in conjunction with the first switching unit, from the first current supply unit One of the pair of plane plates based on the electromagnetic force generated by the direction of the current flowing through the conductor line formed on each surface of the pair of plane plates, the output having a pair of plane plates facing each other if Is supplied to one end of a flat speaker that vibrates both flat plates and outputs sound, or a driving current based on a modulation signal from the pulse width modulation means and a modulation signal phase-inverted by the phase inversion means Is supplied to one end of another electrodynamic speaker that outputs sound, and in conjunction with the first switching means, the second current supply means And a fourth switching means for switching whether to supply the output to the other end of the planar speaker or to the other end of the other electrodynamic speaker (Claim 4). .

  Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

  Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing an audio output system according to the present invention. This audio output system is roughly composed of an amplifier device A, a planar speaker 1 and an electrodynamic speaker 2. In this audio output system, a planar speaker 1 and an electrodynamic speaker 2 can be connected as speakers to the amplifier device A, and either one of the speakers can be selected and used. is there.

  That is, the amplifier device A is provided with a switching unit 10 (described later) that can be operated by the user. When the user selects, for example, the planar speaker 1 by the operation of the switching unit 10, the planar speaker 1. Can be used, and the electrodynamic speaker 2 can be used when the user selects the electrodynamic speaker 2.

  As shown in FIG. 2, the flat speaker 1 includes a pair of horizontally long rectangular flat plates 3a and 3b arranged to face each other at a predetermined interval, and either one of the pair of flat plates 3a and 3b or When both the flat plates 3a and 3b vibrate, the surrounding air vibrates and a sound is output.

  The flat speaker 1 is not shown in FIG. 2, but one of the pair of flat plates 3a and 3b is a fixed plate that does not vibrate, and the other flat plate is a vibrating plate that vibrates. The other flat plate vibrates in a substantially normal direction with respect to its surface. Between one flat plate and the other flat plate, a spacer (not shown) arranged as a frame body is provided along the periphery of the flat plate. In the operation principle of the flat speaker 1 described below, the pair of flat plates 3a and 3b will be described as diaphragms.

  The pair of flat plates 3a and 3b are made of, for example, ceramic and have a thickness of about 1 to 30 μm. On the surface of the pair of flat plates 3a and 3b, meander line-shaped conductor lines 4a and 4b are formed, respectively. One end of the conductor line 4a is connected to the positive terminals of a pair of terminals provided at one end in the longitudinal direction of the flat plate 3a, for example, and the other end of the conductor line 4a is the other end in the longitudinal direction of the flat plate 3a. To one end and is connected to a negative terminal provided near the positive terminal. The configuration of the conductor line 4b with respect to the flat plate 3b is the same as the configuration of the conductor line 4a with respect to the flat plate 3a.

  The conductor lines 4a and 4b formed on the pair of flat plates 3a and 3b are arranged so that the conductor lines 4a and 4b face each other. The conductor lines 4a and 4b may be formed by attaching a conductor to the flat plates 3a and 3b, or may be formed by etching. Further, the conductor lines 4a and 4b are more preferably light weights that do not hinder the vibration of the flat plates 3a and 3b.

  A drive current output from the amplifier device A flows through each of the conductor lines 4a and 4b. The driving current has a direction of flowing from the positive terminal (+) to the negative terminal (−) and a direction of flowing from the negative terminal (−) to the positive terminal (+) shown in FIG.

  As shown in FIG. 2, when a drive current flows through the conductor lines 4a and 4b of the pair of flat plates 3a and 3b in directions opposite to each other, as shown in FIGS. Repulsive forces F1, F2 due to Lorentz force act between 4b. More specifically, when the drive current I1 flowing through the conductor line 4a of the one flat plate 3a and the drive current I2 flowing through the conductor line 4b of the other flat plate 3b are in opposite directions, the periphery of the one conductor line 4a The magnetic field lines E2 are generated counterclockwise by the drive current I2 flowing through the other conductor line 4b. Therefore, an upward electromagnetic force (repulsive force) F1 in FIG. 3 is generated in one conductor line 4a by the drive current I1 and the magnetic force line E2.

  Further, around the other conductor line 4b, a magnetic force line E1 is generated clockwise by the drive current I1 flowing through the one conductor line 4a. Therefore, a downward electromagnetic force (repulsive force) F2 in FIG. 3 is generated in the other conductor line 4b by the drive current I2 and the magnetic force line E1.

  On the other hand, when drive currents flow in the same direction as shown in FIG. 4, attractive forces F1 'and F2' due to Lorentz force act between the conductor lines 4a and 4b as shown in FIGS. That is, when the drive current I1 flowing through the conductor line 4a of one plane plate 3a and the drive current I2 flowing through the conductor line 4b of the other plane plate 3b are in the same direction, the drive current I The downward electromagnetic force (attraction) F1 ′ in FIG. 5 is generated by I1 and the magnetic force line E2. In the other conductor line 4b, an upward electromagnetic force (attracting force) F2 'in FIG. 5 is generated by the drive current I2 and the magnetic force line E1.

  The directions in which the electromagnetic forces F 1, F 2, F 1 ′, and F 2 ′ are generated are made to coincide with the sound emission direction in the flat speaker 1. That is, by causing the drive current to flow by alternately changing the direction in which the drive current flows to the conductor lines 4a and 4b of any of the flat plates 3a and 3b, any of the flat plates 3a and 3b vibrate. Sound is output by vibration. In the flat speaker 1, both the flat plates 3a and 3b may be vibrated.

  The electrodynamic speaker 2 is provided with a substantially cone-shaped cone paper and a voice coil (both not shown) as a diaphragm, and the cone paper vibrates when a drive current flows through the voice coil. To do. In the audio output system according to the present embodiment, an electrostatic speaker or the like may be used instead of the electrodynamic speaker as the speaker that can be switched to the planar speaker. That is, as will be described later, any speaker may be used as long as it is driven on the basis of a pulse width modulated modulation signal and its inverted modulation signal.

  Returning to FIG. 1, the amplifier device A includes an audio signal generation source 5, a pulse width modulation (PWM) unit 6, a clock generation unit 7, first and second edge trigger units 8 a and 8 b, and a phase inversion unit 9. A switching unit 10, first to fourth level shift units 11a to 11d, first to fourth driving units 12a to 12d, first to fourth switching elements 13a to 13d, and first and second filters. The parts 14a and 14b are schematically configured. The audio signal generation source 5 may be provided separately from the amplifier device A.

  In the amplifier device A according to the present embodiment, switching between the planar speaker 1 and the electrodynamic speaker 2 is performed by a switching operation in a switching unit 10 described later in detail. More specifically, the planar speaker 1 and the electrodynamic speaker 2 both vibrate and generate sound due to the drive current supplied to them, but the signal form of the supplied drive current is different. However, since a part of the circuit that generates the signal form can be shared, in the present embodiment, a common part can be shared in the configuration of the amplifier device A so that the flat speaker 1 and the electrodynamic speaker are shared. 2 and switching and using them together.

  The audio signal generation source 5 generates an audio signal as an input signal. The audio signal generated from the audio signal generation source 5 is input to the pulse width modulation unit 6.

  The pulse width modulation unit 6 performs pulse width modulation on the audio signal output from the audio signal generation source 5 to generate and output a modulation signal (a pulse signal having a constant cycle in which the duty ratio changes according to the amplitude of the audio signal). Is. The modulation method in the pulse width modulation unit 6 may be any one of a method using a sawtooth wave and a triangular wave, a method using charge / discharge of a capacitor, and other methods. The modulation signal output from the pulse width modulation unit 6 is input to the second edge trigger unit 8b, the second switch SW2 (described later) of the switching unit 10, and the phase inversion unit 9, respectively.

  The clock generator 7 generates a reference clock signal that is a clock signal having a duty ratio of approximately 50%. The reference clock signal is used as a reference clock for generating a modulation signal in the pulse width modulation unit 6 and is used for frequency division in the first edge trigger unit 8a.

  The first edge trigger unit 8a detects a fall or rise of the reference clock signal from the clock generation unit 7 and generates a clock signal having a frequency twice that of the original reference clock signal. It is. The output of the first edge trigger unit 8a is input to a first switch SW1 (described later) of the switching unit 10.

  The second edge trigger unit 8b detects the falling or rising of the modulation signal, which is a pulse signal from the pulse width modulation unit 6, and generates a modulation signal having a frequency twice that of the original modulation signal. Circuit. The output of the second edge trigger unit 8b is input to a second switch SW2 (described later) of the switching unit 10. The half-divided clock signal output from the first edge trigger unit 8 a and the half-divided modulation signal output from the second edge trigger unit 8 b are used for driving the flat speaker 1.

  The phase inversion unit 9 inverts the phase of the pulse signal from the pulse width modulation unit 6. The pulse signal whose phase has been inverted is input to a first switch SW1 (described later) of the switching unit 10. The inverted modulation signal output from the phase inversion unit 9 and the modulation signal output from the pulse width modulation unit 6 are used for driving the electrodynamic speaker 2.

  The switching unit 10 is for switching signals output to the planar speaker 1 and the electrodynamic speaker 2, and is composed of first to fourth switches SW1 to SW4 as shown in FIG. Yes. The first to fourth switches SW1 to SW4 are switched in conjunction with, for example, a user's operation. For example, when set to the upper side in FIG. 1, the first to fourth switches SW1 to SW4 are switched to the flat speaker 1 side and set to the lower side in FIG. If it does, it will switch to the electrodynamic speaker 2 side.

  That is, the first switch SW1 switches between the clock signal divided by two from the first edge trigger unit 8a and the phase-inverted modulation signal and supplies them to the first and second level shift units 11a and 11b. belongs to. The second switch SW2 switches between the half-divided modulation signal from the second edge trigger unit 8b and the original non-divided modulation signal and supplies them to the third and fourth level shift units 11c and 11d. Is for.

  The third switch SW3 is for switching whether the signals from the first and second switching elements 13a and 13b are supplied to the flat speaker 1 or the first filter unit 14a (the electrodynamic speaker 2). belongs to. The fourth switch SW4 is for switching whether the signals from the third and fourth switching elements 13c and 13d are supplied to the flat speaker 1 or the second filter unit 14b (the electrodynamic speaker 2). belongs to.

  The first to fourth level shift units 11a to 11d are for shifting the reference potential in the pulse width modulation unit 6 to a reference potential for driving the first to fourth switching elements 13a to 13d. The first to fourth level shift units 11a to 11b correspond to first to fourth drive units 12a to 12d, which will be described later, and to first to fourth switching elements 13a to 13d, respectively.

  The 1st thru | or 4th drive parts 12a-12d are for driving the 1st thru | or 4th switching elements 13a-13d. The 1st thru | or 4th drive parts 12a-12d respond | correspond to each of the 1st thru | or 4th switching elements 13a-13d mentioned later.

  The first to fourth switching elements 13a to 13d are configured by power amplification type field effect transistors such as MOS-FETs. The first and second switching elements 13a and 13b are connected in series between the positive and negative power supply voltages + V and -V, and their midpoints are connected to the speaker side to constitute a so-called half-bridge circuit. The first and second switching elements 13a and 13b are alternately turned on and off based on the frequency-divided clock signal or the phase-inverted modulation signal from the first edge trigger unit 8a.

  More specifically, the first switching element 13a is a p-type, and when the clock signal divided by two is at a high level, the first switching element 13a is turned on and supplies a positive power supply voltage + V to the speaker side ( Current "). The second switching element 13b is an n-type, and when the clock signal divided by two is at a low level, the second switching element 13b is turned on and supplies a negative power supply voltage -V to the speaker side ("sink current" is supplied to the speaker side To do).

  Similarly to the first and second switching elements 13a and 13b, the third and fourth switching elements 13c and 13d are connected in series between the positive and negative power supply voltages + V and −V, and the middle point thereof is Connected to the speaker side to form a half-bridge circuit. The third and fourth switching elements 13c and 13d are alternately turned on and off based on the half-divided modulation signal from the second edge trigger unit 8b or the original modulation signal.

  More specifically, the third switching element 13c is a p-type, and when the modulation signal divided by two is at a high level, the third switching element 13c is turned on and supplies a positive power supply voltage + V to the speaker side ( Current "). The fourth switching element 13d is an n-type, and when the original modulation signal is at a low level, the fourth switching element 13d is turned on and supplies a negative power supply voltage −V to the speaker side (provides “suction current” to the speaker side).

  The first and second filter units 14a and 14b are configured by an LC circuit including a coil and a capacitor (both not shown), for example. The first and second filter units 14a and 14b are low-pass filters having a cutoff frequency of 60 kHz, for example. The first filter unit 14 a removes harmonic components of the positive and negative power supply voltages + V and −V switched by the first and second switching elements 13 a and 13 b, and supplies the output to the electrodynamic speaker 2. The second filter unit 14 b removes the harmonic components of the positive and negative power supply voltages + V and −V switched by the third and fourth switching elements 13 c and 13 d and supplies the output to the electrodynamic speaker 2.

  Next, the effect | action by the said structure is demonstrated. First, for example, a case where the switching unit 10 is switched to the planar speaker 1 side will be described with reference to a timing chart shown in FIG. When the switching unit 10 is switched to the planar speaker 1 side, the first to fourth switches SW1 to SW4 are switched to the upper side in FIG.

  The reference clock signal (see FIG. 6B) output from the clock generator 7 is generated as a clock signal (see FIG. 6D) divided by 2 in the first edge trigger unit 8a. The clock signal divided by two is supplied to the first and second level shift units 11a and 11b via the first switch SW1.

  The half-divided clock signal supplied to the first and second level shift units 11a and 11b is shifted to the reference potential of the first and second switching elements 13a and 13b, and the first and second drive units 12a and 12b The signals are converted into signals for driving the first and second switching elements 13a and 13b. And it outputs to the 1st and 2nd switching element 13a, 13b at a predetermined timing, respectively.

  The first and second switching elements 13a and 13b are turned on and off based on drive signals output from the first and second drive units 12a and 12b. That is, as shown in FIG. 6D, in the high-level period T1 of the divided clock signal 2, the first switching element 13a is turned on while the second switching element 13b is turned off. Thereby, the positive power supply voltage + V is supplied to one flat plate 3a of the flat speaker 1 through the third switch SW3.

  In the low-level period T2 of the frequency-divided clock signal by 2, the first switching element 13a is turned off while the second switching element 13b is turned on. As a result, the negative power supply voltage −V is supplied to the planar speaker 1 via the third switch SW3. That is, the driving current in the opposite direction flows through one flat plate 3a of the flat speaker 1 during the period T1 when the frequency-divided clock signal 2 is at a high level.

  On the other hand, an audio signal (see FIG. 6 (a)) as an analog signal output from the audio signal generation source 5 is subjected to pulse width modulation in the pulse width modulation section 6 to be a modulated signal (FIG. 6 (c) ))). The modulation signal output from the pulse width modulation unit 6 is generated as a modulation signal (see FIG. 6E) divided by two in the second edge trigger unit 8b. This half-divided modulation signal is supplied to the third and fourth level shift units 11c and 11d via the second switch SW2.

  The divide-by-two modulation signals supplied to the third and fourth level shift units 11c and 11d are shifted to the reference potentials of the third and fourth switching elements 13c and 13d, and the third and fourth drive units 12c and 12d The signals are converted into signals for driving the third and fourth switching elements 13c and 13d. And it outputs to the 3rd and 4th switching elements 13c and 13d at a predetermined timing, respectively.

  The third and fourth switching elements 13c and 13d are turned on and off based on drive signals output from the third and fourth drive units 12c and 12d. That is, as shown in FIG. 6E, in the high-level period T3 of the divide-by-2 divided signal, the third switching element 13c is turned on, while the fourth switching element 13d is turned off. Thereby, the positive power supply voltage + V is supplied to the other flat plate 3b of the flat speaker 1 through the fourth switch SW4.

  In the low-level period T4 of the divide-by-2 modulation signal, the third switching element 13c is turned off and the fourth switching element 13d is turned on. As a result, the negative power supply voltage −V is supplied to the planar speaker 1 via the fourth switch SW4. That is, the driving current in the reverse direction flows through the other flat plate 3b of the flat speaker 1 during the period T3 when the frequency-divided modulation signal is at the high level.

  That is, referring to FIG. 6 (f), in the period t1, the divided-by-2 clock signal is at a high level, while the divided-by-2 divided signal is at a low level, so that the flat plates 3a, 3b of the flat speaker 1 are used. A reverse drive current flows through each of the conductor lines 4a and 4b. Further, in the period t2, both the divided clock signal 2 and the divided signal 2 are high level, so that the drive currents in the same direction flow through the conductor lines 4a and 4b.

  Further, in the period t3, since the divided-by-2 clock signal is at a low level, the divided-by-2 modulation signal is at a high level, a reverse drive current flows through each conductor line 4a, 4b. In the period t4, both the divided clock signal 2 and the divided modulation signal 2 are at the low level, so that drive currents in the same direction flow through the conductor lines 4a and 4b.

  As shown in FIGS. 2 to 5, when the drive currents flowing through the conductor lines 4a and 4b are in the same direction, attractive forces F1 ′ and F2 ′ are generated in the pair of flat plates 3a and 3b. In the reverse direction, repulsive forces F1 and F2 are generated on the pair of flat plates 3a and 3b. The pair of flat plates 3a and 3b are vibrated by the attractive forces F1 'and F2' and the repulsive forces F1 and F2, and sound is output from the flat speaker 1 due to the vibration.

  Next, for example, a case where the switching unit 10 is switched to the electrodynamic speaker 2 side will be described with reference to a timing chart shown in FIG. When the switching unit 10 is switched to the electrodynamic speaker 2 side, the first to fourth switches SW1 to SW1 are switched to the lower side in FIG.

  An audio signal (see FIG. 7A) output as an analog signal output from the audio signal generation source 5 is subjected to pulse width modulation in the pulse width modulation unit 6 based on the reference clock signal from the clock generation unit 7 and is digitally converted. It is converted into a modulated signal (see FIG. 7C) as a signal. The modulation signal output from the pulse width modulation unit 6 is supplied to the third and fourth level shift units 11c and 11d via the second switch SW2. The modulation signal output from the pulse width modulation unit 6 is phase-inverted by the phase inversion unit 9 and supplied to the first and second level shift units 11a and 11b via the first switch SW1.

  The inverted modulation signal (see FIG. 7D) that has been phase-inverted by the phase inverter 9 and supplied to the first and second level shifters 11a and 11b is the reference of the first and second switching elements 13a and 13b. It is shifted to a potential and converted into a signal for driving the first and second switching elements 13a and 13b in the first and second driving units 12a and 12b. And it outputs to the 1st and 2nd switching element 13a, 13b at a predetermined timing, respectively.

  The first and second switching elements 13a and 13b are turned on and off based on drive signals output from the first and second drive units 12a and 12b. That is, as shown in FIG. 7D, in the high-level period T5 of the inverted modulation signal, the first switching element 13a is turned on while the second switching element 13b is turned off. As a result, the positive power supply voltage + V is output to the first filter unit 14a via the third switch SW3. In the 1st filter part 14a, after a harmonic component is removed, it supplies to the one terminal of the electrodynamic speaker 2. FIG.

  In the low-level period T6 of the inverted modulation signal, the first switching element 13a is turned off while the second switching element 13b is turned on. Thereby, the negative power supply voltage -V is output to the first filter unit 14a via the third switch SW3, and after the harmonic component is removed, it is supplied to one terminal of the electrodynamic loudspeaker 2.

  On the other hand, the modulation signals supplied to the third and fourth level shift units 11c and 11d are shifted to the reference potentials of the third and fourth switching elements 13c and 13d, and the third and fourth drive units 12c and 12d receive the first signals. 3 and the fourth switching elements 13c and 13d are converted into signals for driving. And it outputs to the 3rd and 4th switching elements 13c and 13d at a predetermined timing, respectively.

  The third and fourth switching elements 13c and 13d are turned on and off based on drive signals output from the third and fourth drive units 12c and 12d. That is, as shown in FIG. 7C, in the low-level period T7 of the modulation signal, the third switching element 13c is turned off while the fourth switching element 13d is turned on. Thereby, the negative power supply voltage −V is output to the second filter unit 14b via the fourth switch SW4. In the second filter unit 14b, the negative power supply voltage -V is supplied to the other terminal of the electrodynamic speaker 2 after the harmonic component is removed.

  Further, in the high-level period T8 of the modulation signal, the third switching element 13c is turned on, while the fourth switching element 13d is turned off. Accordingly, the positive power supply voltage + V is output to the second filter unit 14b via the fourth switch SW4, and after the harmonic component is removed, the positive power supply voltage + V is supplied to the other terminal of the electrodynamic speaker 2.

  In the electrodynamic loudspeaker 2, the drive current flowing in a voice coil (not shown) is alternately inverted based on the modulation signal and the inverted modulation signal, so that the cone paper as the diaphragm is vibrated based on the inversion operation. Due to this vibration, sound is output from the electrodynamic speaker 2.

  Thus, in the audio output system according to the present embodiment, the planar speaker 1 and the electrodynamic speaker 2 can be connected together, and the switching operation is performed by the switching unit 10, whereby the planar speaker 1. And the electrodynamic speaker 2 can be easily switched and driven. Therefore, it is not necessary to separately prepare an amplifier device dedicated to the planar speaker 1 or an amplifier device dedicated to the electrodynamic speaker 2, and a versatile audio output system can be provided.

  The planar speaker 1 and the electrodynamic speaker 2 are different in signal form for driving, but in the amplifier device A of this embodiment, the circuit for generating the drive signal is partially shared. Therefore, the number of parts can be reduced and the apparatus can be downsized. Specifically, the audio signal generation source 5, the pulse width modulation unit 6, the clock generation unit 7, the first to fourth level shift units 11a to 11d, the first to fourth driving units 12a to 12d, and the first to fourth. The switching elements 13a to 13d can be shared.

  FIG. 8 is a block diagram showing a modification of the audio output system. The configuration of this modified example is that the power amplifying unit including the level shift unit, the driving unit, and the switching element is provided independently for each of the planar speaker 1 and the electrodynamic speaker 2, and the switching unit 10 is omitted. Different from the embodiment described above.

  More specifically, the output stage of the first edge trigger unit 8a includes first and second level shift units 11a and 11b, first and second drive units 12a and 12b, and first and second switching elements 13a and 13b. And the third and fourth level shift units 11c and 11d, the third and fourth drive units 12c and 12d, and the third and fourth switching elements 13c and 13d are connected to the output of the second edge trigger unit 8b. Has been. The planar speaker 1 is connected to the midpoint of the first and second switching elements 13a and 13b and the midpoint of the third and fourth switching elements 13c and 13d.

  Further, the fifth and sixth level shift units 11e and 11f, the fifth and sixth driving units 12e and 12f, and the fifth and sixth switching elements 13e and 13f are connected to the output stage of the pulse width modulation unit 6, Seventh and eighth level shift units 11g and 11h, seventh and eighth drive units 12g and 12h, and seventh and eighth switching elements 13g and 13h are connected to the output stage of the phase inverting unit 9. An electrodynamic speaker is connected to the midpoint of the fifth and sixth switching elements 13e and 13f and the midpoint of the seventh and eighth switching elements 13g and 13h via the first and second filter portions 14a and 14b. 2 is connected. Other configurations are substantially the same as those in the above-described embodiment.

  Also in this configuration, the planar speaker 1 and the electrodynamic speaker 2 can be connected to the amplifier device A ′, and a signal for driving the planar speaker 1 and the electrodynamic speaker 2 such as the pulse width modulation unit 6 or the like. Can be partially shared. Further, in the audio output system of this modification, the switching unit 10 is omitted, so that the user does not need to switch between the planar speaker 1 and the electrodynamic speaker 2 according to use, and the switching effort can be saved. it can.

  Of course, the scope of the present invention is not limited to the above-described embodiment, and the circuit configuration shown in the above embodiment is an example, and various circuits can be applied as long as they have equivalent functions. Can do. For example, FIG. 1 and FIG. 8 show block configuration diagrams of an audio output system according to the present invention, but the present invention is not limited to this block.

It is a block block diagram which shows the audio | voice output system which concerns on this invention. It is a schematic block diagram of a planar speaker, and shows a case where repulsive force is generated between conductor lines. It is an operation | movement principle figure of a flat type speaker, and shows the case where a repulsive force arises between conductor lines. It is a schematic block diagram of a planar speaker, and shows a case where an attractive force is generated between conductor lines. It is an operation | movement principle figure of a flat type speaker, and shows the case where attractive force arises between conductor lines. It is a timing chart for demonstrating the effect | action of an audio | voice output system, and shows the case where a switching part is switched to the planar speaker side. It is a timing chart for demonstrating the effect | action of an audio | voice output system, and shows the case where the switching part is switched to the electrodynamic type speaker side. It is a block block diagram which shows the modification of an audio | voice output system. It is a figure for demonstrating the principle of operation of a planar speaker, and shows the case where repulsive force arises between conductor lines. It is a figure for demonstrating the principle of operation of a planar speaker, and shows the case where attractive force arises between conductor lines.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Planar speaker 2 Electrodynamic speaker 3a, 3b Planar board 4a, 3b Conductor line 5 Audio signal generation source 6 Pulse width modulation part 7 Clock generation part 8a 1st edge trigger part 8b 2nd edge trigger part 9 Phase inversion part 10 Switching unit 11a first level shift unit 11b second level shift unit 11c third level shift unit 11d fourth level shift unit 12a first drive unit 12b second drive unit 12c third drive unit 12d fourth drive unit 13a first switching Element 13b Second switching element 13c Third switching element 13d Fourth switching element 14a First filter part 14b Second filter part SW1 First switch SW2 Second switch SW3 Third switch SW4 Fourth switch

Claims (4)

A signal source that generates an audio signal as an input signal can be connected,
Clock generating means for generating a reference clock; and
Pulse width modulation means for pulse-modulating an input signal from the signal source based on a reference clock from the clock generation means and outputting a modulation signal;
Clock dividing means for dividing a reference clock from the clock generating means;
Modulation signal dividing means for dividing the modulation signal from the pulse width modulation means;
Phase inversion means for inverting the phase of the modulation signal from the pulse width modulation means;
First current supply means for switching a positive and negative power supply voltage based on the level of a supplied signal and supplying it as a drive current to a subsequent stage;
A second current supply means provided separately from the first current supply means, which switches positive and negative power supply voltages based on the level of the supplied signal and supplies them as a drive current to the subsequent stage;
First switching means for switching the reference clock frequency-divided by the clock frequency dividing means and the modulation signal phase-inverted by the phase inversion means to be supplied to the first current supply means;
In conjunction with the first switching means, the modulation signal divided by the modulation signal dividing means and the modulation signal modulated by the pulse width modulation means are switched and supplied to the second current supply means. A second switching means;
One or both of the pair of flat plates based on the electromagnetic force generated by the direction of the current flowing in the conductor line formed on each surface of the pair of flat plates A flat speaker that outputs sound by vibrating a flat plate;
Another electrodynamic speaker that outputs sound by being supplied with a drive current based on the modulation signal from the pulse width modulation means and the modulation signal phase-inverted by the phase inversion means;
In conjunction with the first switching means, it is switched whether the drive current from the first current supply means is supplied to one end of the planar speaker or one end of the other electrodynamic speaker. Third switching means;
In conjunction with the first switching means, switching between supplying the drive current from the second current supply means to the other end of the planar speaker or the other end of the other electrodynamic speaker is switched. A fourth switching means;
An audio output system comprising: A first low-pass filter means for removing a harmonic component of one output of the third switching means between one output end of the third switching means and the other electrodynamic speaker. Intervened,
Between the one output end of the fourth switching means and the other speaker, a second low-pass filter means for removing harmonic components of one output of the fourth switching means is interposed. The audio output system according to claim 1. A signal source that generates an audio signal as an input signal can be connected,
Clock generating means for generating a reference clock; and
Pulse width modulation means for pulse-modulating an input signal from the signal source based on a reference clock from the clock generation means and outputting a modulation signal;
Clock dividing means for dividing a reference clock from the clock generating means;
Modulation signal dividing means for dividing the modulation signal from the pulse width modulation means;
Phase inversion means for inverting the phase of the modulation signal from the pulse width modulation means;
One of the pair of flat plates based on the electromagnetic force generated by the direction of the current flowing through the conductor line formed on each surface of the pair of flat plates, having a pair of opposed flat plates A flat speaker that vibrates and outputs sound;
First current supply means for switching positive and negative power supply voltages based on the level of the reference clock frequency-divided by the clock frequency dividing means and supplying the drive current to one end of the planar speaker;
Second current supply means for switching a positive and negative power supply voltage based on the level of the modulation signal divided by the modulation signal frequency dividing means and supplying it as a drive current to the other end of the planar speaker;
Another electrodynamic speaker that outputs sound by being supplied with a drive current based on the modulation signal from the pulse width modulation means and the modulation signal phase-inverted by the phase inversion means;
Third current supply means for switching positive and negative power supply voltages based on the level of the modulation signal modulated by the pulse width modulation means to supply one end of the other electrodynamic speaker as a drive current;
Fourth current supply means for switching positive and negative power supply voltages based on the level of the modulation signal phase-inverted by the phase inversion means to supply the other end of the other electrodynamic speaker as a drive current;
An audio output system comprising: A signal source that generates an audio signal as an input signal can be connected,
Clock generating means for generating a reference clock; and
Pulse width modulation means for pulse-modulating an input signal from the signal source based on a reference clock from the clock generation means and outputting a modulation signal;
Clock dividing means for dividing a reference clock from the clock generating means;
Modulation signal dividing means for dividing the modulation signal from the pulse width modulation means;
Phase inversion means for inverting the phase of the modulation signal from the pulse width modulation means;
First current supply means for switching a positive and negative power supply voltage based on the level of a supplied signal and supplying it as a drive current to a subsequent stage;
A second current supply means provided separately from the first current supply means, which switches positive and negative power supply voltages based on the level of the supplied signal and supplies them as a drive current to the subsequent stage;
First switching means for switching the reference clock frequency-divided by the clock frequency dividing means and the modulation signal phase-inverted by the phase inversion means to be supplied to the first current supply means;
In conjunction with the first switching means, the modulation signal divided by the modulation signal dividing means and the modulation signal modulated by the pulse width modulation means are switched and supplied to the second current supply means. A second switching means;
In conjunction with the first switching means, the output from the first current supply means has a pair of opposing flat plates, and the current flowing through the conductor lines formed on the respective surfaces of the pair of flat plates Based on the electromagnetic force generated by the direction, either one or both of the pair of flat plates is vibrated and supplied to one end of a flat speaker that outputs sound, or from the pulse width modulation means And a third switching means for switching whether to supply to one end of another electrodynamic speaker that outputs sound by being supplied with a drive current based on the modulation signal and the modulation signal phase-inverted by the phase inversion means. ,
In conjunction with the first switching means, a second switch is made to switch whether the output from the second current supply means is supplied to the other end of the planar speaker or the other end of the other electrodynamic speaker. 4 switching means;
An audio amplifier comprising:

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