JP4230332B2 - Audio equipment and audio system - Google Patents

Description

  The present invention relates to an audio device or an audio system to which a speaker whose driving capability is insufficient with an internal power supply alone is connected.

  Conventionally, portable audio devices have existed. An audio device refers to a sound reproduction device such as a stereo. Here, it is normal usage for a portable audio device to listen to sound using headphones or earphones, and listening to sound using a speaker is left to a stationary audio device. However, portable audio devices are convenient to carry, and are convenient for users if they can connect to speakers and listen to sounds.

  In a conventional portable audio device, when sound is reproduced externally using a speaker, there is a method of connecting a speaker to a headphone terminal of the audio device and driving the speaker to make a sound. However, in this case, the output terminal of the portable audio device is originally for headphones, and when a speaker is connected, the audio output level is low in the portable audio device, and the speaker cannot be sounded sufficiently. Therefore, the audio output from the headphone terminal is once input to the amplifier, the audio output is amplified by the amplifier, and the sound is emitted from the speaker. Therefore, in this case, an amplifier and a power supply circuit that supplies power to the amplifier are required (for example, Patent Document 1).

  FIG. 4 shows a configuration shown as a specific conventional example of an audio device, and a part of the “sound source device, portable sound source device, and acoustic system” (Patent Document 1) is modified in order to compare with the embodiment of the present invention. It is a thing. In the audio device 10 of FIG. 4, the sound source unit 31 is controlled by the microcomputer 21 to which power is supplied from the power supply / charging circuit 61, and a sound is emitted from the headphone 71 connected to the headphone terminal 41 provided in the sound source unit 31. ing.

Further, FIG. 5 shows that the audio device 10 is connected to an external speaker system 80 through the headphone terminal 41, and is amplified by an amplifier circuit 82 built in the speaker system 80 to drive the speaker 81 to produce a sound. It shows the state. The amplifier circuit 82 of FIG. 5 is for amplifying an audio signal, and at the same time, the speaker system 80 is provided with a power supply circuit 83 for supplying power to the amplifier circuit 82. At this time, a charger 85 for charging the power supply / charging circuit 61 is used. As shown in FIG. 5, the audio device 10, the speaker system 80, and the charger 85 are separated separately. When the charger 85 is not used, the power source / charging circuit 61 becomes an internal power source isolated from the outside.
Japanese Patent Laid-Open No. 2001-275260 (released on October 5, 2001) JP 2002-246852 (published August 30, 2002)

  However, in the configuration of the conventional audio device as shown in FIGS. 4 and 5, when a speaker connected to the headphone terminal is driven without using an amplifier such as the amplifier circuit 82, a desired sound can be heard. Can not. This is because the output terminal of a conventional portable audio device is provided for connecting headphones or earphones, and therefore the output voltage is low.

  The reason why the voltage of the output terminal for headphones or earphones is low is that if the voltage is high, the headphones or earphones are burdened and may break down. Also, in this type of audio device, the output and power supply time are insufficient to drive the speaker with only the internal power supply of the audio device. For this reason, when connecting a speaker to a portable audio device and listening to the sound, it is necessary to input the output from the headphone terminal to the amplifier for the speaker once and amplify with the amplifier before driving the speaker. Furthermore, since power must be supplied to the amplifier, a dedicated power supply circuit for that purpose is also required. The power supply circuit 83 in FIG. 5 is a power supply circuit for this purpose, and is provided separately from the charger 85. Therefore, there is a problem that the cost is increased in order to drive the speaker.

  The present invention has been made in view of the above problems, and its purpose is to eliminate the need for a dedicated power supply circuit for operating an external amplifier and an amplifier provided for a speaker whose driving capability is insufficient with only an internal power supply, An object of the present invention is to provide an audio device and an audio system capable of driving a speaker while reducing the cost.

In order to solve the above problems, the audio device according to the present invention does not pass through the low-pass filter after being generated from the power supply and the first output terminal that outputs the signal that has passed through the low-pass filter after being generated from the power supply. A second output terminal that outputs a signal, a power supply voltage for generating a signal voltage when a signal is output from the first output terminal as a first power supply voltage, and the second output An audio device that makes the second power supply voltage larger than the first power supply voltage when a power supply voltage for generating a signal voltage when a signal is output from a terminal is the second power supply voltage, and an analog signal Or a 1-bit signal conversion means for converting an audio signal composed of a digital signal assigned and expressed in multiple bits into a 1-bit signal assigned in 1 bit; A positive-phase amplification unit that amplifies one signal of the one-bit signal and a negative-phase amplification unit that amplifies the other signal that is in reverse phase with the one signal of the one-bit signal, and amplifies the one-bit signal A switching amplification means; a first low-pass filter that passes the low-frequency component of the output signal of the positive-phase amplification means; and a second low-pass filter that passes the low-frequency component of the output signal of the negative-phase amplification means, The first output terminal has an output portion of the first low-pass filter and an output portion of the second low-pass filter as output terminals, and the second output terminal is an output portion of the positive phase amplification means and the output of the negative phase amplification means. And the first power supply voltage is a power supply voltage for generating a signal voltage when the signal is output from the first output terminal by the switching amplification means. , The second power supply voltage is characterized by a power supply voltage for the signal voltage generated by said switching amplifier means when outputting a signal from said second output terminal.

  In order to solve the above problems, the audio device according to the present invention is characterized in that an earphone or a headphone can be connected to the first output terminal, and a speaker can be connected to the second output terminal.

  In order to solve the above-described problems, the audio device according to the present invention can incorporate a rechargeable battery, and the speaker is provided on a charging stand for charging the rechargeable battery built in the audio device. And

  In order to solve the above problem, the audio device according to the present invention is characterized in that the power supply voltage is set to the second power supply voltage when the audio device is set on the charging stand.

  In order to solve the above problems, an audio device according to the present invention includes a charging stand detection unit that detects that the audio device is set on the charging stand, and the audio device is configured to be detected by the charging stand detection unit. When it is detected that the battery is set on the charging stand, the power supply voltage is set to the second power supply voltage.

In order to solve the above problems, the audio device according to the present invention does not pass through the low-pass filter after being generated from the power supply and the first output terminal that outputs the signal that has passed through the low-pass filter after being generated from the power supply. An audio device comprising two output terminals, a second output terminal for outputting a signal, wherein an audio signal composed of an analog signal or a digital signal assigned and expressed in multiple bits is represented by 1 bit. 1-bit signal converting means for converting to an assigned 1-bit signal, normal-phase amplifying means for amplifying one signal of the 1-bit signal, and amplifying the other signal having an opposite phase to the one signal of the 1-bit signal Switching amplifying means for amplifying the 1-bit signal with a reverse phase amplifying means, and a low frequency range of the output signal of the normal phase amplifying means A first low-pass filter that allows a component to pass through, and a second low-pass filter that allows a low-frequency component of the output signal of the antiphase amplification means to pass through, wherein the first output terminal includes an output unit of the first low-pass filter and the first low-pass filter The output section of the second low-pass filter is an output terminal, and the second output terminal is an output section of the output section of the positive phase amplification means and the output section of the negative phase amplification means .

  In order to solve the above problems, an audio device according to the present invention is configured to make a power supply voltage for generating a voltage of a signal output from the first output terminal and the second output terminal variable by the power supply. Features.

  In order to solve the above problems, an audio system according to the present invention is characterized in that the audio device is combined with at least one of earphones, headphones, and speakers.

  In order to solve the above-described problems, an audio system according to the present invention includes a combination of the audio device capable of incorporating a rechargeable battery and a charging stand for charging the rechargeable battery incorporated in the audio device. Features.

  As described above, the audio device according to the present invention includes the two output terminals of the first output terminal and the second output terminal, and makes the second power supply voltage larger than the first power supply voltage. Only when driving a speaker having insufficient driving capability, an additional amplifier and a dedicated power supply circuit are not required, and the cost can be reduced. Moreover, even if it is a portable audio apparatus, there exists an effect that a desired sound can be heard from a speaker.

  In addition, as described above, the audio device according to the present invention includes a 1-bit signal conversion unit, a switching amplification unit including a normal phase amplification unit and a reverse phase amplification unit, a first low-pass filter, and a second low-pass filter. The first output terminal includes an output section of the first low-pass filter and an output section of the second low-pass filter, and the second output terminal includes an output section of the positive phase amplification means and the negative phase amplification. The output portion of the means is an output terminal, and the first power supply voltage is a power supply voltage for generating a signal voltage when the signal is output from the first output terminal by the switching amplification means, and the second power supply voltage is A power supply voltage for generating a signal voltage when the signal is output from the second output terminal by the switching amplification means.

  As a result, when the speaker is driven, the use of a 1-bit signal reproduction circuit eliminates the need for a dedicated amplifier and a dedicated power supply circuit, thereby reducing the cost.

  In addition, as described above, the audio device according to the present invention can connect an earphone or a headphone to the first output terminal and a speaker to the second output terminal.

  Thereby, when listening to music with earphones or headphones, a sufficient output can be obtained with the signal after passing through the LPF. Further, if the speaker is connected directly rather than taking a signal after the LPF, a sufficient output can be obtained if the voltage is increased. As a result, it is possible to use headphones or earphones and speakers without using an amplifier in one audio device.

  In addition, as described above, the audio device according to the present invention can incorporate a rechargeable battery, and the speaker is provided on a charging stand for charging the rechargeable battery built in the audio device.

  Thus, there is an effect that music can be easily listened to without using a space for placing a speaker and occupying a large area on a desk or the like.

  In addition, as described above, the audio device according to the present invention sets the power supply voltage as the second power supply voltage when the audio device is set on the charging stand.

  Therefore, when an audio device is connected to a speaker that requires a larger sound output than headphones or the like, sufficient power can be automatically supplied from the charging stand, and sound with a high output level can be sufficiently emitted from the speaker. As a result, the user's operation is simplified.

  In addition, as described above, the audio device according to the present invention sets the power supply voltage as the second power supply voltage when the charging device detection unit detects that the audio device is set on the charging device.

  Thereby, it is possible to adjust the power supply voltage for generating the signal voltage by distinguishing the connection of the speaker from the connection of the headphones by the connection to the charging stand of the audio device.

  The audio device according to the present invention includes two output terminals, the first output terminal and the second output terminal, as described above.

  As a result, the power supply voltage for the second output terminal for generating the signal voltage is differentiated from that for the first output terminal, and when the speaker is driven, a separate amplifier and dedicated power supply circuit are not required, thereby reducing costs. This produces an effect of becoming an audio device suitable for a possible configuration.

  In addition, as described above, the audio device according to the present invention includes a 1-bit signal conversion unit, a switching amplification unit including a normal phase amplification unit and a reverse phase amplification unit, a first low-pass filter, and a second low-pass filter. The first output terminal includes an output section of the first low-pass filter and an output section of the second low-pass filter, and the second output terminal includes an output section of the positive phase amplification means and the negative phase amplification. The output part of the means is an output terminal.

  As a result, there is an effect that the audio device is suitable for a configuration that can reduce the cost by using a 1-bit signal reproduction circuit without using a dedicated amplifier and a dedicated power supply circuit.

  In addition, as described above, the audio device according to the present invention varies the power supply voltage for generating the voltage of the signal output from the first output terminal and the second output terminal by the power supply.

  As a result, there is an effect that an audio device suitable for increasing the power supply voltage for the second output terminal separately from that for the first output terminal is obtained.

  Further, as described above, the audio system according to the present invention is a combination of the audio device and at least one of earphones, headphones, and speakers.

  As a result, there is an effect that it is possible to provide a system configuration suitable for using an audio device capable of reducing the cost by separately requiring an amplifier and a dedicated power supply circuit when driving a speaker.

  In addition, as described above, the audio system according to the present invention is a combination of the audio device in which a rechargeable battery can be incorporated and a charging stand for charging the rechargeable battery incorporated in the audio device.

  As a result, there is an effect that it is possible to provide a system configuration suitable for using an audio device capable of reducing the cost by separately requiring an amplifier and a dedicated power supply circuit when driving a speaker.

The embodiment of the present invention will be described with reference to FIGS. 1 to 3 as follows.
First, an embodiment when driving headphones with a portable audio device will be described with reference to FIG. 1, and then an embodiment when driving a speaker with a portable audio device will be described with reference to FIG. 2, and finally FIG. Will be described.

  FIG. 1 shows a configuration of portable audio device 100 as an audio device according to the present embodiment, and a state in which headphones 701 are driven by portable audio device 100.

  First, an internal structure of the portable audio device 100 surrounded by a broken line in FIG. 1 will be described. The portable audio device 100 is an audio device including a digital amplifier (class D amplifier) that performs switching amplification of an audio signal. The portable audio device 100 includes a ΔΣ block 101 (which includes a ΔΣ conversion circuit (not shown)), a microcomputer (hereinafter referred to as “amplifier”). 201, upper gate drives 301 and 302, lower gate drives 401 and 402, output transistors 501 to 504, coils 505 and 506, capacitors 507 and 508, and resistance components 509 and 510 of coils 505 and 506 , A positive phase analog output terminal 511, a negative phase analog output terminal 512, a positive phase digital output terminal 513, a negative phase digital output terminal 514, a power supply terminal 515, and a power supply / charging circuit 601. The power source / charge circuit 601 can incorporate a rechargeable battery. Furthermore, the portable audio device 100 is combined with a headphone 701 and a charging stand 800 described later to constitute an audio system.

  Each will be described below.

  The ΔΣ block (1-bit signal conversion means) 101 includes a ΔΣ conversion circuit (not shown), and an analog signal or a multi-bit digital signal input to the ΔΣ conversion circuit is used as a PDM signal as a series of binary signals or Create a PWM signal. Further, the ΔΣ block 101 generates two series of 1-bit signals (a normal phase signal and a negative phase signal) based on the generated binary signal (PDM signal, PWM signal). The normal phase signal is output from the 1-bit normal phase output terminal 102, and the negative phase signal is output from the 1-bit negative phase output terminal 103.

  The microcomputer 201 is provided to control the audio system, and is always supplied with power from the power / charge circuit 601. Further, the microcomputer and the ΔΣ block 101 are connected by a control signal line CL.

  The 1-bit signal output from the 1-bit positive phase output terminal 102 is input to the input terminals of the upper gate drive 301 and the lower gate drive 401. The 1-bit signal output from the 1-bit reverse phase output terminal 103 is input to the input terminals of the upper gate drive 302 and the lower gate drive 402. A power supply voltage is applied to the upper gate drives 301 and 302 and the lower gate drives 401 and 402 from the power supply / charge circuit 601 according to the control of the microcomputer 201.

  The drains of the output transistors 501 and 502, which are N-channel MOS transistors, are connected to the power supply terminal 515, respectively. The source of the output transistor 501 is connected to the drain of the output transistor 503, and the source of the output transistor 502 is connected to the drain of the output transistor 504. The sources of the output transistors 503 and 504 are connected to the ground. The configuration in which the output transistors 501 to 504 are connected as described above is a full bridge circuit.

  The output of the upper gate drive 301 is input to the output transistor 501, the output of the upper gate drive 302 is input to the output transistor 502, the output of the lower gate drive 401 is input to the output transistor 504, and the output of the lower gate drive 402 Is input to the output transistor 503. The upper gate drives 301 and 302, the lower gate drives 401 and 402, and the output transistors 501 to 504 constitute switching amplification means. The upper gate drive 302, the lower gate drive 401, and the output transistors 502 and 504 constitute positive phase signal amplification means for switching and amplifying the positive phase signal. The upper gate drive 301, the lower gate drive 402, The output transistors 501 and 503 constitute antiphase signal amplifying means for switching and amplifying antiphase signals.

  Two output lines are connected to a connection point between the output transistor 502 and the output transistor 504. First, a coil 505 is connected to one output line. The opposite side of the coil 505 with respect to the output transistors 502 and 504 is connected to the positive phase analog output terminal 511 via the resistance 509 of the coil 505. A positive phase digital output terminal 513 is connected to the other output line. A capacitor 507 is connected between the load side of the coil 505 and the ground, and the coil 505 and the capacitor 507 constitute an LPF (low-pass filter) (hereinafter referred to as a first LPF (first low-pass filter)).

  On the other hand, two output lines are also connected to a connection point between the output transistor 501 and the output transistor 503. First, a coil 506 is connected to one output line. The other side of the coil 506 with respect to the output transistors 501 and 503 is connected to the negative phase analog output terminal 512 via the resistance component 510 of the coil 506. Further, a negative phase digital output terminal 514 is connected to the other output line. A capacitor 508 is connected between the load side of the coil 506 and the ground, and the coil 506 and the capacitor 508 constitute an LPF (low-pass filter) (hereinafter referred to as a second LPF (second low-pass filter)). .

  The positive phase analog output terminal 511 is connected to the common mode output terminal which is the output section of the first LPF, and the negative phase analog output terminal 512 is connected to the common mode output terminal which is the output section of the second LPF. Will be. Further, a headphone 701 is connected between the normal phase analog output terminal 511 and the negative phase analog output terminal 512. As a result, the signal input to the headphones 701 is in the normal mode. Thus, the normal phase analog output terminal 511 and the negative phase analog output terminal 512 constitute a first output terminal.

  Further, the positive phase digital output terminal 513 is connected to a common mode output terminal which is an output portion of a circuit constituted by the output transistor 502 and the output transistor 504, and the negative phase digital output terminal 514 is an output. It is connected to a common mode output terminal which is an output part of a circuit composed of the transistor 501 and the output transistor 503. Further, a speaker 801 is connected between the positive phase digital output terminal 513 and the negative phase digital output terminal 514 as described later. As a result, the signal input to the speaker 801 is in the normal mode. Thus, the positive phase digital output terminal 513 and the negative phase digital output terminal 514 constitute a second output terminal.

  The operation of the audio system configured as described above will be described.

  The ΔΣ block 101 creates a PDM signal or PWM signal as a series of binary signals from the input analog signal or multi-bit digital signal. Further, the ΔΣ block 101 generates two series of 1-bit signals (a normal phase signal and a negative phase signal) based on the generated binary signal (PDM signal, PWM signal). Thereafter, the 1-bit digital signal generated by the ΔΣ block 101 is input to the upper gate drives 301 and 302 and the lower gate drives 401 and 402 through the 1-bit positive phase output terminal 102 and the 1-bit reverse phase output terminal 103. . These signals are converted into predetermined voltages required to operate the output transistors 501, 502, 503, and 504 constituting the output full bridge circuit by the upper gate drives 301 and 302 and the lower gate drives 401 and 402. As a result, the output transistors 501 to 504 perform a switching operation.

  By this switching operation, an amplified 1-bit signal is obtained. This signal is a signal generated from the power supply through the power supply terminal 515 and the ground. A power supply voltage for obtaining this signal voltage when driving the headphones 701 is defined as a first power supply voltage. Among the obtained signals, a signal obtained from the connection point between the output transistor 502 and the output transistor 504 is obtained from the connection point between the output transistor 501 and the output transistor 503 through the first LPF composed of the coil 505 and the capacitor 507. The signal is passed through a second LPF comprising a coil 506 and a capacitor 508. Headphone 701 includes a normal-phase analog output 511 terminal that outputs a positive-phase analog signal that is a signal that has passed through the first LPF, and a negative-phase analog output 512 terminal that outputs a negative-phase analog signal that is a signal that has passed through the second LPF. By connecting to, sound can be heard through the headphones 701.

  Next, FIG. 2 will be described. FIG. 2 shows a state in which the portable audio device 100 drives the speaker 801. Below, only a different part from FIG. 1 is demonstrated.

  The internal structure of the portable audio device 100 from the ΔΣ block 101 to the power source / charge circuit 601 is the same as that in FIG. In FIG. 2, the portable audio device 100 is connected to an external charging base 800. The charging stand 800 includes a charging / power supply circuit 901 and a speaker 801, supplies power to the portable audio device 100, and charges a rechargeable battery built in the portable audio device 100.

  The charging / power supply circuit 901 performs a charging / power supply operation to the power supply / charging circuit 601 in the portable audio device 100. This charging / power supply operation is performed when the portable audio device 100 is set on the charging stand 800. Further, when outputting audio using the speaker 801, when the portable audio device 100 is placed on the charging stand 800, the normal phase digital output terminal 513 and the negative phase digital output terminal 514 are connected to the speaker 801 by a connector (not shown). It has become so.

  When the portable audio device 100 is set on the charging stand 800 and the charging stand detection means (not shown) built in the portable audio device 100 detects that the charging stand 800 is set, the power supply / charging circuit 601 The supply voltage of the power supply terminal 515 is increased. That is, the switching operation of the output transistors 501 to 504 generates an amplified 1-bit signal from the power supply via the power supply terminal 515 and the ground. The power supply for obtaining this signal voltage when driving the speaker 801 When the voltage is the second power supply voltage, the second power supply voltage is larger than the first power supply voltage.

  Thereby, when the portable audio device 100 is connected to the speaker 801, the portable audio device 100 distinguishes the connection of the speaker 801 from the connection of the headphones 701, adjusts the power supply voltage for generating the signal voltage, and Since sufficient power supply is automatically performed, a high output level sound can be produced from the speaker 801, so that the user's operation is simplified. The speaker 801 can be driven even if the power supply / charging circuit 601 that is an internal power supply has a small capacity and the output and power supply time are insufficient to drive the speaker 801.

  As described above, the positive phase digital output terminal 513 is connected to the connection point of the output transistors 502 and 504, and the negative phase digital output terminal 514 is connected to the connection point of the output transistors 501 and 503. When the ΔΣ block 101 operates in this state, the operation from the ΔΣ block 101 to the output transistors 501 to 504 performs the same operation as in FIG. A positive phase digital signal from the positive phase digital output terminal 513 and a negative phase digital signal from the negative phase digital output terminal 514 are applied to the speaker 801. As a result, the speaker 801 is driven, and sound is reproduced by the speaker 801.

  In general, a certain output voltage is required to drive a speaker. Further, the coil constituting the LPF has a direct current resistance component like the resistance components 509 and 510, and the output signal that has passed through the LPF cannot sufficiently produce sound due to a voltage drop due to the resistance. Further, the signal to the speaker is not taken after the LPF, but even if the signal is directly connected, the voltage required for the speaker is not satisfied, and the power source needs to be further increased.

  However, as described above, in this embodiment, a signal is directly output without passing through the LPF as in the normal phase digital output terminal 513 and the reverse phase digital output terminal 514, and the power supply / charge circuit 601 Increases the supply voltage of the power supply terminal 515. That is, the voltage applied to the power supply terminal 515 is variable, and when the output signal is output from the normal phase digital output terminal 513 and the negative phase digital output terminal 514, the voltage applied to the power supply terminal 515 is increased. . Therefore, a voltage sufficient to drive the speaker is output, and a sufficient volume can be maintained. In addition, the fact that the signal is output directly without passing through the LPF eliminates the need to configure the coil with a thick wire in order to reduce the DC resistance contained in the coil that constitutes the LPF, and uses small parts. Convenient for portable devices. Therefore, the portable audio device 100 includes two types of output terminals for earphones or headphones and for speakers.

  In addition, such a configuration having two types of output terminals has an upper limit on the voltage that can be generated and driven in the output bridge circuit and the power supply circuit, and it is difficult to increase the voltage of the output path through which the LPF passes. It has a configuration that takes into account. Forcibly increasing the upper limit of the voltage will lead to an increase in cost. For this reason, the LPF coil with a voltage drop is used only when necessary, such as when using headphones, which leads to cost reduction. Furthermore, if only an output terminal dedicated to the speaker is provided, when headphones or earphones are connected to this, the voltage will be too high and the burden on the headphones or earphones will increase, and the output circuit and power supply circuit of the headphones or earphones will There is a risk of failure, but this can also be avoided.

  Thus, in the portable audio device 100, the earphone or the headphone 701 is connected to the normal phase analog output terminal 511 and the negative phase analog output terminal 512, and the speaker 801 is connected to the positive phase digital output terminal 513 and the negative phase digital output terminal 514. It is possible. Thereby, when listening to music with earphones or headphones 701, a sufficient output can be obtained with the signal after passing through the LPF. Further, if the speaker 801 is connected directly instead of taking a signal after the LPF, the voltage can be increased to obtain a sufficient output. As a result, headphones or earphones and speakers can be used without using an amplifier in one audio device.

  In addition, since the speaker 801 is provided on the charging stand 800, a space for placing the speaker is unnecessary, and music can be easily heard without occupying a large area on a desk or the like.

FIG. 3 shows how sound is output from pulses. 3 is obtained by subtracting the voltage between the negative phase digital output terminal 514 and the ground from the voltage between the positive phase digital output terminal 513 and the ground, and the maximum value is V _CC and the minimum value is V _EE. It has become. A voice waveform is extracted from this pulse as shown in the figure. Here, in general, the loudspeaker can operate for output frequencies up to about 20 kHz. On the other hand, the sampling frequency of the 1-bit signal output from the ΔΣ block 101 of this embodiment is several hundred kHz to several MHz. For this reason, the speaker cannot respond directly to the frequency component of the pulse, but can respond only to the low-frequency component contained therein. This is the same operation as the first LPF composed of the coil 505 and the capacitor 507 and the second LPF composed of the coil 506 and the capacitor 508 in FIG. 1, and only the audio signal having a frequency of about 20 kHz at maximum is output from the speaker 801.

  As described above, according to the portable audio device 100 according to the present embodiment, when driving a speaker whose driving capability is insufficient with only an internal power supply, a separate amplifier is used by using a 1-bit signal reproduction circuit. In addition, a dedicated power supply circuit becomes unnecessary, and the cost can be reduced. In particular, there is a great advantage in that a desired sound can be heard from a speaker while being a portable audio device.

  An audio device including a first output terminal that outputs a signal that has been generated from a power supply and passed through the LPF, and a second output terminal that outputs a signal that has been generated from the power supply and has not passed through the LPF, The power supply voltage for the second output terminal that generates the signal voltage is made distinct from that for the first output terminal, and when the speaker is driven, a separate amplifier and dedicated power supply circuit are not required, and the cost can be reduced. The audio device is suitable for a configuration such as the audio device 100.

  Also, a 1-bit signal converting means for converting an audio signal composed of an analog signal or a digital signal expressed by being assigned with multiple bits into a 1-bit signal assigned with 1 bit, and amplifying one of the 1-bit signals. A switching amplification means for amplifying the 1-bit signal by comprising a positive-phase amplification means and a reverse-phase amplification means for amplifying the other signal having the opposite phase to the one signal of the 1-bit signal; A first low-pass filter that allows a low-frequency component of the output signal to pass; and a second low-pass filter that allows a low-frequency component of the output signal of the anti-phase amplification means to pass through, the first output terminal being the first low-pass filter. And the output part of the second low-pass filter are output terminals, and the second output terminal is an output part of the positive phase amplification means and The audio device having the output portion of the reverse phase amplification means as an output terminal can be reduced in cost by using a 1-bit signal reproduction circuit, eliminating the need for a separate dedicated amplifier and dedicated power supply circuit. This is an audio device suitable for such a configuration.

  In addition, an audio device in which a power supply voltage for generating a voltage of a signal output from the first output terminal and the second output terminal is variable by the power supply is used for the second output terminal like the portable audio device 100. Is an audio device suitable for a configuration in which the power supply voltage is increased in distinction from that for the first output terminal.

  Further, if an audio system in which the portable audio device 100 is combined with at least one of the earphone, the headphone 701, and the speaker 801 is configured, a system configuration suitable for using the portable audio device 100 is provided. be able to. In particular, when the portable audio device 100 and the speaker 801 are combined, the speaker 801 does not include an amplifier and its dedicated power supply circuit as in the conventional case, which is convenient when a user forms a system.

  In addition, if an audio system is configured by combining the portable audio device 100 in which the rechargeable battery can be incorporated and the charging stand 800, a system configuration suitable for using the portable audio device 100 can be provided.

  In addition, as described above, since the speaker 801 is provided on the charging stand 800, a space for placing the speaker is unnecessary, and music can be easily heard without occupying a large area on a desk or the like. This is particularly true for portable audio devices such as MD (mini disc) products. Furthermore, as a further application, a mobile phone that is an audio device from the viewpoint of outputting sound can be cited, and by setting it on the charging stand 800 and ringing the speaker 801, it is possible to make a call by hand (hands-free). Become.

  It can be used for audio equipment and audio systems in general, and is particularly useful for portable audio equipment and audio systems such as MD products and mobile phones.

It is a block diagram which shows the structure of the portable audio equipment and audio system which concern on one Embodiment of this invention, and the drive state of headphones. It is a block diagram which shows the structure of the portable audio equipment and audio system which concern on one Embodiment of this invention, and the drive state of a speaker. It is a graph which shows a mode that an audio | voice is output from a speaker by pulse input. It is a block diagram which shows the state which drives the headphones with the conventional portable audio equipment. It is a block diagram which shows the state which drives the external speaker in the state which is charging the conventional portable audio equipment with the charging stand.

Explanation of symbols

100 Portable audio equipment (audio equipment)
101 ΔΣ block (1-bit signal conversion means)
102 1-bit positive phase output terminal 103 1-bit negative phase output terminals 301 and 302 Upper gate drives 401 and 402 Lower gate drives 501 to 504 Output transistor 511 Positive phase analog output terminal 512 Negative phase analog output terminal 513 Positive phase digital output terminal 514 Reverse phase digital output terminal 515 Power supply terminal 601 Power supply / charging circuit 701 Headphone 800 Charging stand 801 Speaker 901 Charging / power supply circuit

Claims (9)

Two output terminals are provided: a first output terminal that outputs a signal that has been generated from a power supply and passed through a low-pass filter; and a second output terminal that outputs a signal that has been generated from a power supply and has not passed through a low-pass filter. A power supply voltage for generating a signal voltage when outputting a signal from the first output terminal is a first power supply voltage, and a power supply for generating a signal voltage when outputting a signal from the second output terminal When the voltage is a second power supply voltage, the audio device makes the second power supply voltage larger than the first power supply voltage ,
1-bit signal conversion means for converting an analog signal or an audio signal composed of a digital signal assigned and expressed in multiple bits into a 1-bit signal assigned in 1 bit, and a positive phase for amplifying one of the 1-bit signals A switching amplifying means for amplifying the 1-bit signal by amplifying means and an anti-phase amplifying means for amplifying the other signal having the opposite phase to the one signal of the 1-bit signal; And a second low-pass filter that passes the low-frequency component of the output signal of the negative phase amplification means, and the first output terminal is an output of the first low-pass filter. And the output part of the second low-pass filter are output terminals, and the second output terminal is the output part of the normal phase amplification means and the reverse The output section of the amplification means is an output terminal, and the first power supply voltage is a power supply voltage for generating a signal voltage when the signal is output from the first output terminal by the switching amplification means, and the second power supply voltage Is a power supply voltage for generating a signal voltage when the signal is output from the second output terminal by the switching amplification means . The audio apparatus according to claim 1 , wherein earphones or headphones can be connected to the first output terminal, and a speaker can be connected to the second output terminal. The audio device according to claim 2 , wherein a rechargeable battery can be built in, and the speaker is provided on a charging stand for charging the rechargeable battery built in the audio device. The audio device according to claim 3 , wherein when the audio device is set on the charging stand, the power supply voltage is set to the second power supply voltage. Charge base detecting means for detecting that the audio device is set on the charging base is provided, and when the charging base detection means detects that the audio device is set on the charging base, the power supply voltage is set. The audio device according to claim 4 , wherein the second power supply voltage is used. Two output terminals are provided: a first output terminal that outputs a signal that has been generated from a power supply and passed through a low-pass filter; and a second output terminal that outputs a signal that has been generated from a power supply and has not passed through a low-pass filter. it an audio device, characterized in that,
1-bit signal conversion means for converting an analog signal or an audio signal composed of a digital signal assigned and expressed in multiple bits into a 1-bit signal assigned in 1 bit, and a positive phase for amplifying one of the 1-bit signals A switching amplifying means for amplifying the 1-bit signal by amplifying means and an anti-phase amplifying means for amplifying the other signal having the opposite phase to the one signal of the 1-bit signal; And a second low-pass filter that passes the low-frequency component of the output signal of the negative phase amplification means, and the first output terminal is an output of the first low-pass filter. And the output part of the second low-pass filter are output terminals, and the second output terminal is the output part of the normal phase amplification means and the reverse Audio equipment, characterized in that the output of the amplifying means and the output terminal. The audio device according to claim 6 , wherein a power supply voltage for generating a voltage of a signal output from the first output terminal and the second output terminal is variable by the power supply. Audio system to the audio device according to any of claims 1 to 5, characterized earphone, headphone, and that the at least one of a speaker comprising the combination. Audio system to the audio device according to any of claims 1 capable of incorporating the rechargeable battery 5, characterized by comprising in combination and the charging base is to charge the rechargeable battery built in the audio device.

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