JP2005236404A - Speaker system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speaker system capable of configuring speaker main bodies to be a cordless type, by providing a charging type internal power supply section and a reception section of voice signal to one or more speaker bodies among a plurality of speakers and providing a charging mechanism section applied to the internal power supply section to the other speaker bodies. <P>SOLUTION: Cordless speakers are employed for rear speakers. The rear speaker bodies 26L, 26R are provided with audio signal receiving sections 40L, 40R, and also the charging type internal power supply section as a power supply section of the audio signal receiving section and an external power supply terminal, and a signal input terminal for receiving the audio signal supplied to the front speakers, in addition to the external power supply terminal. In the case of the 5.1 channel surrounding sound, 6 speakers including center speakers are arranged. Charging for the internal power supply section is made from front speaker bodies 24L, 24R via power supply lines 54L, 54R. The rear speaker bodies are arranged in parallel with the front speaker bodies. Further, the voice signal supplied from the front speaker bodies to the front speakers is supplied to the rear speaker bodies via signal lines 55L, 55R. In the case of the 5.1 channel surrounding sound, a cordless configuration is realized, and in the case of charging, the 3.1 channel surround sound can be enjoyed, while carrying out charging. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a speaker system suitable for application to a 5.1 channel surround system, a 4 channel surround system, or the like.

  Specifically, when a speaker system is configured by a plurality of speaker bodies each having a built-in speaker, the speaker can be driven without particularly drawing signal lines and power lines connected to the speaker body. About the system.

  As a speaker system connected to an audio device, a game software playback device, etc. in order to give a sense of realism in recent audio devices such as a surround stereo or game software playback device, a 5.1 channel surround system or a 4-channel surround system Is often adopted.

  An example of a 5.1-channel surround speaker system will be described with reference to FIG. As shown in FIG. 4, in the room (listening room) 12, with a viewer (listener) 14 as a reference, a center speaker CS is disposed in the center of the front together with the system main body 1, and left and right front speakers on both sides thereof. FL and FR are arranged. Rear speakers RL and RR are disposed on the left and right sides of the viewer 14. Next to the center speaker CS, a subwoofer SW that handles the extremely low frequency range is arranged, and a system for listening to music, sound effects of a game, etc. using these five speakers is a 5.1 channel surround type speaker system 10. is there.

  The system main body 1 is composed of a plurality of components, and in the case of the figure, an AD player (record player) 4 and a pre-main amplifier 6 as well as various decks 2 such as DAT, DVD, and CD are equipped. Video monitors (CRTs, LCDs, screens, etc., not shown) are also provided for enjoying home theater.

  The center speaker CS is built in the center speaker body 22, and the left and right front speakers FL, FR are built in the left and right front speaker bodies 24L, 24R, respectively. Similarly, the rear speakers RL and RR are also incorporated in the left and right rear speaker bodies 26L and 26R, and the subwoofer SW is housed in the subwoofer body 28.

  The system main body 1 and the center speaker main body 22 are connected by a signal line 23 (a connection cable for left and right audio signals (L + R)). Similarly, the system main body 1 and the front speakers FL and FR are connected by signal lines 30L and 30R, and the subwoofer SW is also connected by the same signal line 34, and the system main body 1 and the rear speakers RL and RR are connected to each other. Are also connected by similar signal lines 32L and 32R.

  As described above, in the speaker system 10 or the like that employs the 5.1 channel surround system, signal lines are routed through the room 12 due to the use of a large number of speakers, and particularly for the rear speakers RL and RR. Then, the signal lines 32L and 32R are routed along the wall of the room 12.

  Therefore, when rearranging the speakers or cleaning the room, this signal line often becomes an obstacle. If there is no signal line, such inconvenience is eliminated. It has already been proposed to drive a speaker without a signal line (for example, Patent Documents 1 and 2).

Japanese Patent Laid-Open No. 11-122688 JP 2003-134590 A

  By the way, Patent Document 1 discloses a technology that includes a signal transmission device and a reception device thereof, an electronic musical instrument is disposed on the transmission device side, and a speaker is disposed on the reception device side.

  Since the receiving device side equipped with the speaker requires a signal receiving means, an amplifier for driving the speaker, etc., the audio signal has a cordless configuration, but a power source for driving the signal receiving means, the amplifier, etc. And the power cord must be provided on the receiving device side.

  Therefore, since it is not completely cordless, the power cord may be an obstacle when rearranging the speakers or cleaning the room. Further, since the technique of Patent Document 1 is not applied to a speaker system such as a plurality of speakers, particularly a 5.1 channel surround system or a 4-channel surround system, a technique for making the power cords cordless is not disclosed. .

  Patent Document 2 discloses means for preventing overcharging of an electric double layer capacitor, which is a charging capacitor, in order to eliminate a problem in charging work when realizing a cordless speaker device.

  The speaker device that is the subject of this Patent Document 2 is applied to a speaker device that is separated from the main body of a television receiver for an audio signal received by the television receiver, and is dedicated for making the speaker device cordless. Charging device is required. That is, before driving the speaker device, it is necessary to charge the above-described capacitor using this dedicated charging device.

  Therefore, this patent document 2 describes a specific method for charging a cordless speaker body using a simpler device when some of them are cordless in a speaker system using a plurality of speakers. Not disclosed.

  Therefore, the present invention solves such a conventional problem, and in particular, among a plurality of speakers, at least one speaker body is provided with a rechargeable internal power supply unit and an audio signal receiving unit, A speaker system is proposed in which a charging mechanism for the internal power supply is provided in another speaker main body so that the speaker main body can be configured in a cordless manner.

  In order to solve the above-mentioned problem, the speaker system according to the present invention described in claim 1 is a speaker system using at least two or more speakers in addition to the system main body, and includes one or more built-in speakers. The speaker main body is configured as a cordless speaker main body provided with an audio signal receiving unit in the speaker main body, and a rechargeable internal power supply unit for the receiving unit is further provided in the wireless speaker main body, and the other speaker main body Is provided with a charging mechanism for the internal power supply, and is charged through the charging mechanism when the internal power supply is required.

  The present invention is applied to a speaker system using a plurality of speakers such as the 5.1 channel surround system and the 4 channel surround system. In the case of the 5.1 channel surround system, four speakers (center speaker CS and a pair of front speakers FL, FR and subwoofer SW) are arranged on the front side of the viewer (listener), and two speakers are arranged on the back side. (Rear speakers RL, RR) are arranged.

  These six speakers are all connected with signal lines for audio signals, but in the present invention, signal lines are eliminated particularly for the rear speakers. That is, it is set as a cordless speaker (wireless speaker). For this reason, the cordless speaker main body incorporating the rear speaker is provided with an audio signal (L, R) receiving unit, and the audio signal transmitting unit is provided on the speaker system main body (the speaker main unit incorporating the center speaker) side. Is provided.

  Further, the cordless speaker main body is provided with a rechargeable power source (such as a power source using a secondary battery) as a power source for the audio signal receiving unit, and an external power terminal for charging the power source. Preferably, in addition to the external power supply terminal, a signal input terminal for receiving audio signals (L, R) supplied to the front speaker is provided.

  When enjoying music in 5.1 channel surround, 6 speakers including the center speaker are arranged so that normal 5.1 channel surround is achieved. The main body of the two rear speakers (cordless speaker main body) is provided with an audio signal receiving unit, so that the internal power supply unit is activated and the audio signal transmitted from the system main body side is received. Since the rear speaker can be driven, the original 5.1 channel surround can be enjoyed.

  When the charging capacity of the internal power supply unit becomes insufficient, charging is performed via the external power supply terminal. For example, this charging is performed through a connector constituting a charging mechanism provided in the front speaker body. Therefore, the rear speaker body is juxtaposed with the front speaker body. Furthermore, audio signals (L, R) supplied from the system main body to the front speaker are supplied to the rear speaker via a signal input terminal provided on the rear speaker main body.

  As a result, the internal power supply unit provided in the rear speaker body is charged, and at the same time, the same left and right audio signals as the front speaker are supplied to the rear speaker, so that 3.1 channel surround can be enjoyed while charging. be able to.

  The front speaker main body and the rear speaker main body can be connected by a connection cable (power supply line and audio signal signal line). In order to do this, since it is necessary to supply power to the front speaker body from the system body, the front speaker body and the system body are connected by a connection cable (power line). By using the power line, a dedicated charging device for the cordless speaker body is not required.

  In this way, by providing a rechargeable internal power supply unit, an audio signal receiving unit and a charging external power supply terminal in the rear speaker body, and providing a charging mechanism unit for the internal power supply unit in the other speaker body. Since the rear speaker body can be configured in a cordless manner, 5.1 channel surround or 4 channel surround can be enjoyed without routing signal lines or power lines. When charging, you can enjoy 3.1 channel surround at the same time as charging.

  According to the present invention, an easy-to-use speaker system can be constructed by eliminating signal lines and charging power lines from the rear speaker body. In particular, when the present invention is applied to a 5.1-channel surround speaker system, the signal lines for the two rear speakers can be omitted, which is convenient when rearranging.

  If the audio signal supplied to the front speaker is also supplied to the rear speaker during charging, it can be enjoyed as 3.1 channel surround while charging.

  Charging is performed via a power supply line connected to a charging mechanism provided in another speaker body, so that there is an effect that a dedicated charging device for the internal power supply is not required.

Next, a preferred embodiment of the speaker system according to the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a case where the present invention is applied to a 5.1 channel surround speaker system 10. Since this is a 5.1 channel surround speaker system, a total of six speakers are used as shown in FIG.

  The arrangement of the speakers is also as described in the conventional example of FIG. 4, and the L and R front speakers FL and FR are arranged on the left and right sides of the center speaker CS. Then, L and R rear speakers RL and RR are arranged on both sides of the listener 14 on the back side, and a subwoofer SW that handles a low frequency range of 100 Hz or less is arranged on the center speaker CS side to construct the speaker system 10. Is done.

  As described above, the system main body 1 includes various components such as a deck 2 that receives audio signals, video signals, and the like that receives, demodulates, reproduces, amplifies, and outputs audio and game video. Equipped. In this example, an AD player 4 and a pre-main amplifier 6 are provided in addition to the deck 2 as in the conventional example of FIG. A video monitor or the like is provided as necessary.

  In the present invention, a transmitter 36 for transmitting audio signals to be supplied to the rear speakers RL and RR is provided in the system body 1. When listening by 5.1 channel surround, the transmission unit 36 is driven to transmit audio signals (for example, radio waves) to the rear speakers RL and RR.

  The system main body 1 and the center speaker main body 22 are connected by a signal line 23 for an audio signal (L + R). Similarly, the audio signal (L + R) signal line 34 is connected between the system body 1 and the subwoofer SW, and the left and right audio signal signal lines 30L and 30R are connected to the front speakers FL and FR. Is connected. Further, power lines (power cables) 49L and 49R used for charging are led out from the system body 1 to the front speaker bodies 24L and 24R. The power supply lines 49L and 49R will be described later.

  The signal line 30L and the power supply line 49L and the signal line 30R and the power supply line 49R may use separate cables as shown in the figure, or may use combined cables.

  The system body 1 is provided with L and R connectors 50L and 50R for connecting the signal lines 30L and 30R and the power supply lines 49L and 49R, respectively. In contrast, the left and right front speaker bodies 24L and 24R are provided with connectors 51L and 51R for connection.

  On the other hand, the rear speaker bodies 26L and 26R are provided with receiving units 40L and 40R for receiving audio signals, respectively, and power sources for driving the receiving units 40L and 40R having the receiving antennas 41L and 41R, respectively. Section (which is an internal power supply section, which will be described later). This internal power supply is configured to be rechargeable.

  Thus, by providing the receiving units 40L and 40R and the rechargeable power supply unit, the rear speaker bodies 26L and 26R can be configured as cordless speaker bodies. Hereinafter, the rear speaker bodies 26L and 26R will be described as cordless speaker bodies with the same reference numerals.

  These cordless speaker main bodies 26L and 26R are further provided with connectors 43L and 43R. The connectors 43L and 43R are connectors used when the power supply units in the cordless speaker bodies 26L and 26R require charging. The power supply terminals for charging the power supply units, and in this example, the rear speakers are also used for charging. Both audio signal input terminals for driving RL and RR are provided.

  Further, among the plurality of speaker bodies arranged on the front side of the listener 14, in this example, the front speaker bodies 24L and 24R are provided with the charging mechanism section for the internal power supply section described above.

  This charging mechanism is configured as a simple connector, and a pair of connectors (51L, 44L) and (51R, 44R) provided on the input side and the output side of the power source line and the signal line to the speaker main body, respectively. ).

  In the speaker system 10 configured as described above, in the 5.1 channel surround listening mode which is a normal usage mode, the speaker arrangement is as shown in FIG. When the system main body 1 is turned on, audio signals are output from the left and right front speakers FL and FR and the subwoofer SW as well as the center speaker CS. Furthermore, by setting the transmission unit 36 and the reception units 40L and 40R to the operating state, the R and L channel audio signals transmitted from the transmission unit 36 can be received by the reception units 40L and 40R, respectively. The audio signals L and R of the L and R channels can be output from the speakers RL and RR, and thereby 5.1 channel surround can be enjoyed.

  When the cordless speaker bodies 26L and 26R are charged, the cordless speaker bodies 26L and 26R are performed via the front speakers 24L and 24R as shown in FIG. Therefore, the L-channel cordless speaker body 26L is placed close to the L-channel front speaker body 24L and the R-channel cordless speaker body 26R is placed close to the R-channel front speaker body 24R.

  This juxtaposition is very simple. This is because none of the speaker main bodies 26L, 26R has a connection cord such as a signal line or a power line, so that the work of unplugging the power cord from the outlet or collecting the power cord and the signal line is completely unnecessary. is there.

  In a state where the cordless speaker bodies 26L and 26R are juxtaposed, the L channel connectors 44L and 43L are connected by a power line 54L, and in this example, the audio signal signal line 55L is connected between the connectors 44L and 43L. Is connected. As a result, the power line 54L is connected to the power line 49L, and the signal line 55L is connected to the signal line 30L.

  Similarly, the R channel connectors 44R and 43R are connected to the power supply line 54R, and in this example by the audio signal signal line 55R, so that the power supply line 54R is connected to the power supply line 49R. The line 55R is connected to the signal line 30R.

  By making such a connection, when a predetermined DC voltage is applied to the power supply lines 49L and 49R from the system main body 1, the inside of the cordless speaker main bodies 26L and 26R is respectively connected via the power supply lines 49L and 54L and 49R and 54R. The power supply unit is charged. Further, the L and R channel audio signals are supplied to the front speakers FL and FR via the signal lines 30L and 30R, and at the same time, the audio signals are further supplied to the rear speakers RL and RR via the signal lines 55L and 55R, respectively. Therefore, it is possible to enjoy 3.1 channel surround while charging.

  FIG. 3 is a conceptual diagram showing an internal configuration in the connected state of FIG. FIG. 3 particularly shows the configuration on the L channel side. Since the configuration on the R channel side is the same, its configuration and description are omitted.

  The system main body 1 will be described. When an audio receiving deck is exemplified as the deck 2, a broadcast wave received by the antenna 60 is selected by a tuner 62 constituting the audio receiving device 61 and a desired channel is selected. The audio signal is further demodulated at 64 and subjected to signal processing for 5.1 channel surround, and then supplied to a corresponding speaker via a line amplifier.

  Therefore, a center audio signal is first supplied to the center speaker CS via the center line amplifier 66 (66C) and the signal line 23. Next, an audio signal for L channel front is led out to the connector 50L side via the front line amplifier 66F. Similarly, a subwoofer audio signal is derived to the outside via the subwoofer line amplifier 66R.

  Further, among the demodulated audio signals, the audio signals for the rear speakers (L and R channels) are supplied to the transmission unit 36 and transmitted from the transmission antenna 37.

  The system main body 1 is further provided with a recording / reproducing device 65, and 5.1 channel audio signals reproduced from a disc such as a DVD via the above-mentioned line amplifiers 66 respectively correspond to the speakers CS, FL, FR. And the SW are also supplied to the transmitter 36 so that audio signals are supplied to the rear speakers RL and RR. The detailed connection diagram is omitted.

  The system main body 1 is further provided with an operation power supply unit 68. The operation power supply unit 68 is used as all power supplies built in the system main body 1. Further, the operation power supply unit 68 also functions as a power supply unit for charging the cordless speaker bodies 26L and 26R.

  Therefore, in this example, a power switch 69 is connected to a specific power line 67 led out to the outside among the power lines connected to the operation power supply unit 68. The power switch 69 is controlled to be turned on when the internal power supply units in the cordless speaker bodies 26L and 26R are charged.

  This switching control can be controlled by a remote control signal, for example. The power supply line 67 is connected to the power supply line 49L connected to the connector 50L, and the power switch 69 is controlled to be turned on based on the power-on signal received by the remote control receiver 70. The reason why the predetermined DC voltage is applied to the power supply line 67 only when the cordless speaker bodies 26L and 26R are in the charging mode in this way is because safety is taken into consideration.

  The remote control receiver 70 is used to control not only the system main body 1 but also the entire speaker system 10.

  Next, the configuration of the front speaker body 24L will be described. The front speaker main body 24L incorporates the above-described front speaker FL, but there are only the connection connectors 51L and 44L that constitute a pair of charging mechanisms. Therefore, the connectors 51L and 44L are connected to each other by the two connection lines 91 and 92 inside the main body.

  The cordless speaker main body 26L as the rear speaker main body is configured as follows. The reception unit 40L will be described. An audio signal is received by the antenna 41L and the receiving circuit (high frequency circuit) 71, and the received audio signal is demodulated by the receiving circuit 71. The demodulated audio signal is supplied to the rear speaker RL via the amplifier 72 and the changeover switch 74.

  An internal power supply unit 78 is further provided in the cordless speaker body 26L. The internal power supply unit 78 is a rechargeable power supply unit, and uses, for example, a secondary battery. The internal power supply voltage of the internal power supply unit 78 is supplied as a drive voltage to each circuit of the receiving unit 40L described above via the power switch 80.

  The internal power supply voltage is also supplied as an operating voltage for the voltage detection / control unit 82 provided for detecting the applied voltage when an external DC voltage for charging is applied. The terminal voltage of the internal power supply unit 78 is monitored by the voltage detection unit 84 to detect whether the operation voltage is sufficient. In this example, lighting control is performed such that an indicator lamp, for example, the LED 86 controlled by the output of the voltage detection unit 84 is turned on when the voltage is higher than a predetermined voltage, and the LED 86 is blinked when the voltage is lower than the predetermined voltage. The viewer can determine whether or not to charge based on the lighting state of the LED 86.

  In order to charge the internal power supply unit 78 from the outside, in this example, the internal power supply unit 78 is connected to a power supply terminal 94a provided on the connector 43L via a power switch 80 and a backflow prevention diode 76.

  When charging the internal power supply unit 78, by turning on the power switch 80, a predetermined DC voltage is applied to the internal power supply unit 78 from the outside via the power supply terminal 94a. The internal power supply 78 is charged by this voltage application. The DC voltage applied from the outside is used not only as a charging voltage for the internal power supply unit 78 but also as a driving voltage for the receiving unit 40L.

  Meanwhile, in addition to the received audio signal, the above-described changeover switch 74 is supplied with an audio signal via the signal input terminal 94b provided in the connector 43L. In the case of 5.1 channel surround, the audio signal for the rear speaker received from the antenna 41L is switched, and the audio for the front speaker supplied to the front speaker main body 24L is provided so that the audio can be viewed as 3.1 channel surround at the time of charging. This is for switching to a signal.

  Therefore, a voltage detection / control unit 82 for controlling the changeover switch is provided. A DC voltage applied to the power supply terminal 94a is supplied to the voltage detection / control unit 82 as an operating voltage via the backflow prevention diode 76, and a direct current between the backflow prevention diode 76 and the power supply terminal 94a is supplied. A voltage is supplied as a detection voltage.

  When no DC voltage is applied to the power supply terminal 94a, no detection voltage is supplied to the voltage detection / control unit 82. In this case, the changeover switch 74 maintains the original switching state as shown by the solid line. As a result, the audio signal supplied to the terminal a side of the changeover switch 74 is output from the rear speaker RL. That is, it is a normal 5.1 channel surround mode.

  However, when charging the internal power supply unit 78, the rear speaker main body 26L is juxtaposed in the vicinity of the front speaker main body 24L, and the power supply line 94L is connected to the power supply terminal 94a from the outside (in other words, from the front speaker main body 24L). Therefore, at this time, a predetermined detection voltage is applied to the voltage detection / control unit 82 via the power supply terminal 94a, and the application state of the DC voltage is detected.

  As a result, the changeover switch 74 is switched by the output from the voltage detection / control unit 82 as shown by a broken line. Since the L channel audio signal is supplied to the terminal b side of the changeover switch 74 via the signal input terminal 94b, the same audio signal as that of the front speaker FL is output from the rear speaker RL. Therefore, in this case, the 3.1 channel surround mode is set.

  Thus, when charging the internal power supply 78 of the cordless speaker body 26L, charging can be performed while listening in the 3.1 channel surround mode. In other words, you can enjoy 3.1 channel surround while charging.

  Note that the above-described reverse current blocking diode 76 drives the receiving unit 40L with the internal power supply unit 78 alone, and the voltage detection / control unit 82 uses the voltage of the internal power supply unit 78 as an external charging voltage. This is to prevent detection.

  The power switch 80 described above is controlled to be turned on / off based on a remote control signal received by a remote control receiver 88 provided inside. In this example, when the speaker system 10 is not in an operating state, that is, when the entire system is at rest, the power switch 80 is turned off to avoid wasting power. During charging, only the front speaker bodies 24L and 24R may be driven. At this time, the supply of the operating voltage to the receiving units 40L and 40R may be stopped.

  In the above-described embodiments, the present invention is applied to the 5.1 channel surround type speaker system. However, it can be easily understood that the present invention can be applied to a 4 channel surround type speaker system, for example. Also in this case, the rear speaker side is configured to be a cordless speaker, and a charging unit is provided. A charging mechanism portion is provided on the front speaker side, and by performing signal transmission and charging through the front speaker, charging can be performed while enjoying a two-channel stereo.

  The present invention can be applied to a speaker system adopting a 5.1 channel surround system or a 4 channel surround system.

It is a conceptual diagram which shows the speaker arrangement | positioning relationship at the time of applying the speaker system based on this invention to a 5.1 channel surround system. It is a conceptual diagram which shows the speaker arrangement | positioning relationship in the drive state by 3.1 channel surround when charging a cordless speaker main body. It is a block diagram which shows the connection state at the time of charge. It is a figure which shows the speaker arrangement | positioning relationship by a 5.1 channel surround system.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... System main body, 2 ... Deck, 4 ... Player, 6 ... Pre-main amplifier, 10 ... Speaker system, 12 ... Listening room, 14 ... Listener, 22 ... Center speaker body, 24L, 24R ... front speaker body, 26L, 26R ... rear speaker body (cordless speaker body), 28 ... subwoofer body, 36 ... transmitting unit, 40L, 40R ... receiving Part, 30L, 30R, 55L ... signal line, 49L, 49R, 54L ... power supply line, 43L, 44L, 50L, 50R, 51L ... connector, 94a ... power supply terminal, 94b ... signal Input terminal, 78... Internal power supply unit, 82... Voltage detection / control unit, 74.

Claims (8)

A speaker system using at least two or more speakers in addition to the system main body,
One or more speaker bodies including the above-described speakers are configured as a cordless speaker body including a sound signal receiving unit in the speaker body.
In the cordless speaker body, a rechargeable internal power supply unit for the receiving unit is further provided,
The other speaker body incorporating another speaker is provided with a charging mechanism for the internal power supply,
The speaker system according to claim 1, wherein the power supply unit is charged through the charging mechanism unit when charging is required. 2. The speaker according to claim 1, wherein during the charging, an audio signal supplied to the other speaker body provided with the charging mechanism is supplied to the cordless speaker body provided with the internal power supply. system. 3. The switch according to claim 2, wherein a switching switch for switching between an audio signal output from the receiving unit and an audio signal supplied from the other speaker main body is provided in the cordless speaker main body. Speaker system. In the cordless speaker body, a connector used for charging is provided,
2. The speaker system according to claim 1, wherein the connector includes at least a power supply terminal supplied from the other speaker body side and an input terminal for an audio signal supplied to the other speaker body. A diode for preventing backflow is connected to the power supply terminal side,
An external power supply voltage obtained between the backflow prevention diode and the power supply terminal is supplied to the voltage detection / control unit,
5. The speaker system according to claim 4, wherein the change-over switch is controlled by a detection output when the external power supply voltage is detected. 5. The speaker system according to claim 1, wherein the speaker system is a 5.1 channel surround system or a 4 channel surround system, wherein the cordless speaker body is a rear speaker body. 5. The speaker system according to claim 1, wherein the speaker system is a 5.1-channel surround system or a 4-channel surround system, and the other speaker body is a front speaker body. 5. A speaker system of 1 channel surround system or 4 channel surround system,
2. The speaker system according to claim 1, wherein when the cordless speaker body is being charged, the cordless speaker body is driven so as to be a 3.1 channel surround system.

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