Sound signal output device and sound signal output method

Abstract

To provide a sound signal output device capable of corresponding to the case where a power consumption exceeds a power that can be supplied from an external power supply.SOLUTION: A sound signal output device includes a charging unit 206 that controls charging of a secondary battery 206 with a power from an AC adapter 10, and a switching unit 210a that switches a power source of a power amplifier 214 that amplifies a sound signal Au to either the AC adapter 10 or the secondary battery 206. In a case where the power source is switched to the AC adapter 10 source, the switching unit 210a switches the power source from the AC adapter 10 to the secondary battery 206 when the power from the AC adapter 10 exceeds a predetermined power as the power consumption in the power amplifier 214 increases.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a sound signal output device and a sound signal output method. [Background technology]

[0002] For example, there is known an audio signal output device that amplifies audio signals, such as musical instrument performance signals or microphone audio signals, and outputs them to a speaker, enabling street performances, speeches, and the like, anytime, anywhere. To make audio signal output devices lightweight and convenient to carry, they often use a small, lightweight external power source, such as an AC adapter, as their power source.

[0003] In a sound signal output device, since the input is a sound signal, a momentary large output may be generated. If a momentary large output is generated and the power consumption of the sound signal output device exceeds the capacity of the external power supply, the external power supply may become unable to output. On the other hand, the average power consumed by the sound signal output device is small compared to the momentary large output. For this reason, a technique is known in which the sound signal output device is configured to be able to handle momentary high outputs, rather than determining the rated output of the external power supply according to momentary high outputs (see, for example, Patent Document 1). Specifically, this technique supplies power stored in a capacitor to a load when it is detected that the power consumption of the sound signal output device exceeds the upper limit of the power that can be supplied from the power supply. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-178843 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technology described in Patent Document 1 has a problem in that the amount of power that can be stored in the capacitor is limited, and therefore it cannot handle cases where the power consumption of the sound signal output device frequently exceeds the upper limit of the power that can be supplied from an external power source. [Means for solving the problem]

[0006] A sound signal output device according to one aspect of the present disclosure includes a charging unit that controls charging of a secondary battery using input power from an external power source, and a switching unit that switches the power source of an amplifier that amplifies a sound signal between the external power source and the secondary battery, and when the power source is switched to the external power source and the input power exceeds a predetermined power due to an increase in power consumption in the amplifier, the switching unit switches the power source from the external power source to the secondary battery.

[0007] Another aspect of the present disclosure provides a sound signal output method that controls charging of a secondary battery using input power from an external power source, and when switching the power source of an amplifier unit that amplifies a sound signal to either the external power source or the secondary battery, if the power source is switched to the external power source and the input power exceeds a predetermined power due to an increase in power consumption in the amplifier unit, the power source is switched from the external power source to the secondary battery. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing the configuration of a system including a sound signal output device according to a first embodiment. [Figure 2] 4 is a flowchart showing the operation of the sound signal output device. [Figure 3] 4 is a flowchart showing the operation of the sound signal output device. [Figure 4] 4 is a flowchart showing the operation of the sound signal output device. [Figure 5] FIG. 10 is a diagram illustrating switching of power supply in a normal operation mode. [Figure 6] FIG. 10 is a diagram illustrating switching of charging in an output limit mode. [Figure 7] FIG. 4 is a diagram showing the remaining charge of a secondary battery. [Figure 8] FIG. 10 is a diagram showing the configuration of a system including a sound signal output device according to a second embodiment. [Figure 9] FIG. 10 is a diagram showing the configuration of a system including a sound signal output device according to a third embodiment. [Figure 10] FIG. 10 is a diagram showing the configuration of a system including a sound signal output device according to a modified example. [Figure 11] 10A and 10B are diagrams showing the remaining charge of a secondary battery in a sound signal output device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, sound signal output devices according to embodiments of the present disclosure will be described with reference to the drawings. The embodiments described below are preferred examples, and therefore various technically preferable limitations are applied, but the scope of the present invention is not limited to these embodiments unless otherwise specified in the following description to the effect that the present invention is limited thereto.

[0010] 1 is a block diagram showing the configuration of a system 1 including a sound signal output device 20a according to the first embodiment. The sound signal output device 20a amplifies a sound signal Ain and outputs the amplified sound from a speaker 30.

[0011] The AC adapter 10 is an example of an external power supply that converts AC from a commercial power source into DC and supplies it to the sound signal output device 20a. In this embodiment, the rated output of the AC adapter 10 is, for example, 24 V, 2.5 A (=60 W). The sound signal Ain is an acoustic signal output from a microphone, an electric musical instrument, or a playback device.

[0012] The speaker 30 converts the amplified sound signal into sound, which is a physical vibration, and outputs it. In FIG. 1, the speaker 30 is a so-called full-range type that reproduces a range of sounds from low to high frequencies with one unit, but it may also be a multi-way unit with separate speaker units for each frequency band. In addition, in FIG. 1, for convenience of explanation, the sound signal output device 20a and the speaker 30 are separated, but the sound signal output device 20a and the speaker 30 may be housed in a single housing.

[0013] The sound signal output device 20 a includes a voltage monitoring unit 202 , a charging unit 204 , a secondary battery 206 , a remaining charge detecting unit 208 , a switching unit 210 a , a head amplifier 212 , a power amplifier 214 , a level detecting unit 216 , an attenuation unit 220 , and a control unit 250 . The voltage monitoring unit 202 monitors the voltage Vin input from the AC adapter 10, and outputs a signal Vd indicating the result of the voltage monitoring. The charging unit 204 controls the charging of the secondary battery 206 using the voltage Vin based on the signal Bc. More specifically, the charging unit 204 controls the secondary battery 206 to, for example, not charge, charge at a low speed, or charge at a high speed. The secondary battery 206 is a storage battery that can be repeatedly charged and discharged. As the secondary battery 206, for example, a lithium ion battery is preferable.

[0014] The remaining charge detector 208 detects the charge remaining in the secondary battery 206, that is, the remaining battery charge, from the charging current, voltage, temperature, etc., and outputs a signal Bd indicating the detection result. The switching unit 210a is a double-throw switch circuit that selects one end or the other end in accordance with the signal Se1. When the AC adapter 10 is connected, the voltage Vin is applied to one end of the switching unit 210a, and the voltage Vb output from the secondary battery 206 is applied to the other end. The switching unit 210a selects either the voltage Vin or the voltage Vb and applies it to the power input terminal Pin of the power amplifier 214. Therefore, the switching unit 210a switches the power source of the power amplifier 214 between the voltage Vin and the voltage Vb.

[0015] The head amplifier 212 amplifies the audio signal Ain to a line level or converts it to a lower impedance and outputs it as an audio signal Au. The level detection unit 216 detects the level of the sound signal Au and outputs a signal Ld indicating the detection result. The level of the sound signal Au is, for example, the effective amplitude value of the sound signal. Although the level detection unit 216 directly detects the level of the sound signal Au, since the amplification factor of the head amplifier 212 is fixed, it indirectly detects the level of the sound signal Ain.

[0016] The attenuation unit 220 selects either the sound signal Au or a signal obtained by attenuating the sound signal Au, and supplies the selected signal to the input terminal of the power amplifier 214. In detail, the attenuation unit 220 includes an attenuator (ATT) 222 and a switch 224. The attenuator 222 attenuates the sound signal Au by, for example, 5 dB. The switch 224 selects either the sound signal Au or the signal attenuated by the attenuator 222 in accordance with a signal Se2, and supplies the selected signal to the input terminal of the power amplifier 214. The power amplifier 214 uses the voltage selected by the switching unit 210 a as a power source, amplifies the signal output from the attenuation unit 220 , and supplies the amplified signal to the speaker 30 .

[0017] The control unit 250 is configured with one or more processing circuits such as a DSP (Digital Signal Processor), and controls the switching unit 210a, the charging unit 204, and the switch 224 based on the signals Vd, Bd, and Ld. Specifically, the control unit 250 outputs a signal Se1 for controlling the switching unit 210a based on a signal Vd indicating the result of monitoring the voltage Vin. The control unit 250 also outputs a signal Bc for controlling the charging unit 204 based on a signal Bd indicating the result of detection of the remaining battery charge and a signal Ld indicating the result of detection of the level of the sound signal Au, and outputs a signal Se2 for controlling the switch 224 based on the signal Ld. The control unit 250 may be configured by circuits such as a CPU (Central Processing Unit) and an ASIC (Application Specific Integrated Circuit) in addition to a DSP.

[0018] Next, the operation of the sound signal output device 20a will be described.

[0019] 2 to 4 are flowcharts showing an example of the operation of the sound signal output device 20a. The control unit 250 executes the process shown in Fig. 2 at regular intervals (for example, every 100 ms).

[0020] First, when a power switch (not shown) is turned on, the control unit 250 executes a power source switching process (step S1), and then executes an operation mode switching process (step S2). After the operation mode switching process is executed, the processing procedure returns to step S1 again. That is, in the sound signal output device 20a, as long as the power switch is on, the power source switching process and the operation mode switching process are repeatedly executed.

[0021] FIG. 3 is a flowchart showing an example of the power source switching process in step S1. First, the control unit 250 determines whether or not the AC adapter 10 is connected to the sound signal output device 20a (step S11). Whether or not the AC adapter 10 is connected to the sound signal output device 20a is detected, for example, by determining whether or not the output plug of the AC adapter 10 is inserted into the input jack of the sound signal output device 20a.

[0022] If the AC adapter 10 is connected (if the determination result in step S11 is "Yes"), the control unit 250 determines whether the voltage Vin is equal to or greater than the threshold voltage Vth1 based on the signal Vd (step S12). The threshold voltage Vth1 is a voltage used as a criterion for determining whether the total power consumed by the sound signal output device 20a exceeds the threshold power. Specifically, the threshold voltage Vth1 is set to a voltage below the lower limit of the rated output voltage of the AC adapter 10 and equal to or greater than the voltage at which the protection circuit built into the AC adapter 10 activates. A "protection circuit" is a circuit that protects an external power source by cutting off the output of the external power source. If the rated output voltage of the AC adapter 10 is 24 V ±5%, the lower limit of the rated output voltage is 22.8 V. Furthermore, if the power consumed by the sound signal output device 20a increases and continuously exceeds the rated output power of the AC adapter 10, the output voltage of the AC adapter 10 (the voltage Vin input from the AC adapter 10) drops, activating the protection circuit. For example, if the output voltage of the AC adapter 10 falls below 20.0 V, the protection circuit of the AC adapter 10 activates. In such a case, the threshold voltage Vth1 is set to a voltage in the range of 20.0 V or greater and less than 22.8 V. Setting the threshold voltage Vth1 to a voltage within this range makes it possible to accurately determine when the output voltage of the AC adapter 10 falls below the rated output voltage, while reliably preventing the protection circuit of the AC adapter 10 from activating (i.e., preventing the AC adapter 10 from being able to output).

[0023] If the voltage Vin is equal to or greater than the threshold voltage Vth1 (if the determination result in step S12 is "Yes"), it is determined that the total power consumed by the sound signal output device 20a does not exceed the threshold power. Therefore, the control unit 250 outputs a signal Se1 to the switching unit 210a to select the voltage Vin as the power source for the power amplifier 214 (step S13). As a result, one end is selected in the switching unit 210a, and the power source of the power amplifier 214 becomes the voltage Vin input from the AC adapter 10.

[0024] On the other hand, when the voltage Vin is less than the threshold voltage Vth1, it means that the total power consumed by the sound signal output device 20a exceeds the threshold power, or that some kind of malfunction has occurred in the AC adapter 10. In either case, when the voltage Vin is less than the threshold voltage Vth1, it means that when the voltage Vin input from the AC adapter 10 is used as the power source for the power amplifier 214, the sound signal Au cannot be amplified. Therefore, if the voltage Vin is less than the threshold voltage Vth1 (if the judgment result in step S12 is "No"), the control unit 250 outputs a signal Se1 to the switching unit 210a to select the voltage Vb of the secondary battery 206 as the power source for the power amplifier 214 (step S14). As a result, the switching unit 210a selects the other end, and the power source of the power amplifier 214 becomes the voltage Vb output from the secondary battery 206.

[0025] After executing the process of either step S13 or S14, the control unit 250 executes the next operation mode switching process.

[0026] FIG. 4 is a flowchart showing an example of the operation mode switching process in step S2. First, the control unit 250 determines whether the level of the sound signal Au, which is indicated by the signal Ld as a result of level detection, is equal to or greater than a threshold level Lth1 (step S21). The threshold level Lth1 is a level when there is no sound signal Au that needs to be emitted by the speaker 30, and is set to, for example, zero or a noise floor level.

[0027] If the level of the sound signal Au is equal to or greater than the threshold level Lth1 (if the determination result in step S21 is "Yes"), the control unit 250 determines whether the remaining battery charge indicated by the signal Bd is equal to or greater than a threshold remaining charge Bth1 (step S22). The threshold remaining charge Bth1 is, for example, an amount indicating that the remaining battery charge is 10%.

[0028] If the level of the sound signal Au is equal to or greater than the threshold level Lth1, it means that the sound signal Au needs to be emitted from the speaker 30, and if the remaining battery charge is equal to or greater than the threshold remaining charge Bth1, it means that there is no need to charge the secondary battery 206. Therefore, if the level of the sound signal Au is equal to or greater than the threshold level Lth1 (the judgment result of step S21 is "Yes") and the remaining battery charge is equal to or greater than the threshold remaining charge Bth1 (the judgment result of step S22 is "Yes"), the control unit 250 sets the operating mode to the normal operating mode (step S23).

[0029] The normal operation mode is a mode in which the sound signal Au output from the head amplifier 212 is amplified by the power amplifier 214 without being attenuated by the attenuator 222, and is emitted from the speaker 30, and the secondary battery 206 is not charged. To set the normal operation mode, the control unit 250 outputs a signal Se2 to the switch 224 to select the sound signal Au, and outputs a signal Bc to the charging unit 204 to stop charging the secondary battery 206.

[0030] If the level of the sound signal Au is equal to or greater than the threshold level Lth1 (the judgment result in step S21 is "Yes") but the remaining battery charge is less than the threshold remaining charge Bth1 (the judgment result in step S22 is "No"), the control unit 250 sets the operating mode to the output limit mode (step S24).

[0031] The output limit mode is a mode in which the sound signal Au is attenuated by the attenuator 222 and then amplified by the power amplifier 214, while the secondary battery 206 is charged at a low speed. To switch to the output limit mode, the control unit 250 outputs a signal Se2 to the switch 224 to select the attenuated signal from the attenuator 222, and outputs a signal Bc to the charging unit 204 to charge the secondary battery 206 at a low rate.

[0032] Specifically, the transition to the output limit mode is likely to occur when the system 1 has been used continuously for a relatively long period of time and the remaining charge of the secondary battery 206 is low. An example of an application in which the system 1 is used continuously for a relatively long period of time is playing background music. When the system 1 transitions to the output limit mode, the sound signal Au is attenuated by 5 dB by the attenuator 222 and supplied to the power amplifier 214. However, in such an application, the drop in volume due to the 5 dB attenuation is not noticeable. Therefore, the output limit mode has a significant advantage in that it allows the sound signal Au to be continuously emitted from the speaker 30 while the secondary battery 206 is charged.

[0033] On the other hand, if the level of the sound signal Au is less than the threshold level Lth1 (if the judgment result of step S21 is "No"), the control unit 250 judges whether the state in which the level of the sound signal Au is less than the threshold level Lth1 has continued for a certain period of time (e.g., 5 seconds) (step S25). The operation mode is maintained in the normal operation mode or the output limiting mode until the state in which the level of the sound signal Au is less than the threshold level Lth1 continues for a certain period of time.

[0034] If the level of the sound signal Au remains below the threshold level Lth1, the determinations of steps S21 and S25 are repeated until a certain period of time has elapsed and the determination result of step S25 becomes "Yes." If the determination result of step S25 becomes "Yes," the control unit 250 switches the operation mode to the charging mode (step S26). The charging mode is a mode in which the amplification of the sound signal Au is stopped and the secondary battery 206 is charged at high speed.

[0035] To enter the charging mode, the control unit 250 outputs a signal Bc to the charging unit 204, which causes the charging unit 204 to charge the secondary battery 206 at high speed. Note that to enter the charging mode, the control unit 250 may, for example, stop the operation of the head amplifier 212 using a function not shown. As a result, there is nothing to amplify, so the power consumed by the power amplifier 214 becomes zero and the speaker 30 becomes silent. In the sound signal output device 20a, elements other than the power amplifier 214 continue to consume power.

[0036] After steps S23, S24, and S26 are completed, or if the determination result in step S25 is "No," the control unit 250 ends this operation mode switching process and returns the processing procedure to step S1. In this manner, the processes of steps S1 and S2 are repeatedly executed.

[0037] Next, a specific example of the above-mentioned power source switching process will be described. Fig. 5 is a diagram showing switching of the power source in the normal operation mode. As described above, when the AC adapter 10 is connected to the sound signal output device 20a and the voltage Vin input from the AC adapter 10 is equal to or greater than the threshold voltage Vth1, the AC adapter 10 becomes the power source for the power amplifier 214.

[0038] The total power consumed by the sound signal output device 20a can be divided into the power consumed by the power amplifier 214 and the power consumed by elements other than the power amplifier 214. Of these, the power consumed by the power amplifier 214 varies depending on the level of the sound signal Au. Elements other than the power amplifier 214 include the voltage monitoring unit 202, remaining power detection unit 208, head amplifier 212, level detection unit 216, control unit 250, etc., and the power consumed by these elements does not vary depending on the level of the sound signal Au but is approximately constant. In Fig. 5, the elements other than the power amplifier 214 are referred to as "inside the system." The power consumed inside the system is, for example, 10 W. As mentioned above, the rated output of AC adapter 10 is 60 W. If the power consumed by power amplifier 214, i.e., the power continuously output to speaker 30, is 50 W or less, and the power consumed within the system of 10 W is added, the total will be 60 W or less, so AC adapter 10 will be the power source for power amplifier 214.

[0039] On the other hand, when the AC adapter 10 is connected to the sound signal output device 20a and the power source is the AC adapter 10, if the power output to the speaker 30 momentarily exceeds 50 W, the total power consumed by the sound signal output device 20a exceeds the rated output power of the AC adapter 10, and the voltage Vin falls below the threshold voltage Vth1. As a result, the power source of the power amplifier 214 is switched from the AC adapter 10 to the secondary battery 206, and the speaker 30 continues to emit sound.

[0040] The right column of FIG. 5 shows an example in which the power output to the speaker 30 momentarily becomes 100 W, causing the total power consumed by the sound signal output device 20a to exceed the rated output power of the AC adapter 10, which is 60 W. Furthermore, when the voltage Vin falls below the threshold voltage Vth1 and the power source of the power amplifier 214 is the secondary battery 206, if the voltage Vin recovers to above the threshold voltage Vth1, the power source of the power amplifier 214 is switched from the secondary battery 206 to the AC adapter 10.

[0041] Next, a specific example of the above-mentioned operation mode switching process will be described. Fig. 6 is a diagram showing the transition of operation modes, and Fig. 7 is a diagram showing the allocation of power in the output limit mode and the charging mode. As described above, when the level of the sound signal Au is equal to or greater than the threshold level Lth1 and the remaining battery charge is equal to or greater than the threshold remaining charge Bth1, the operation mode becomes the normal operation mode. On the other hand, when the level of the sound signal Au is equal to or greater than the threshold level Lth1 and the remaining battery charge is less than the threshold remaining charge Bth1, the operation mode becomes the limited output mode.

[0042] The left column of FIG. 7 shows the power allocation by the AC adapter 10 in the output limit mode. In the output limit mode, the attenuator 222 reduces the output of the power amplifier 214 by 5 dB, reducing the output from 100 W to 30 W, for example. In this case, the power consumed within the system is 10 W, leaving a margin of 20 W up to the rated output power of the AC adapter 10. In this embodiment, this 20 W is used to charge the secondary battery 206. In the output limiting mode, the sound signal Au is attenuated by 5 dB by the attenuator 222 and input to the power amplifier 214, so that the power consumed by the power amplifier 214 is reduced, the speaker 30 continues to emit sound, and furthermore, the secondary battery 206, which is in a low charge state, is charged.

[0043] When the operation mode is the normal operation mode or the output limit mode, if the level of the sound signal Au remains below the threshold level Lth1 for a certain period of time, the operation mode shifts to the charging mode. The right column of FIG. 7 shows the power allocation by the AC adapter 10 in the charging mode. In the charging mode, 10 W of the rated output power of the AC adapter 10 is ensured for power consumption within the system, and the remaining 50 W is used to charge the secondary battery 206. Therefore, in the charging mode, the secondary battery 206 is charged at a higher speed than in the output limit mode.

[0044] When the operation mode is the charging mode, if the level of the sound signal Au becomes equal to or greater than the threshold level Lth1, and the remaining battery charge is less than the threshold remaining charge Bth1, the operation mode changes to the output limiting mode, and if the remaining battery charge is equal to or greater than the threshold remaining charge Bth1, the operation mode changes to the normal operation mode. Furthermore, in the output limiting mode, the amount of power that can be used to charge the secondary battery 206 is less than in the charging mode, so the secondary battery 206 is charged at a relatively slower rate than in the charging mode, i.e., at a low rate.

[0045] In the first embodiment, when the power consumption of the sound signal output device 20a exceeds the power that can be supplied from the AC adapter 10, the power source of the power amplifier 214 is switched to the secondary battery 206, so that the power amplifier 214 can continue to amplify the sound signal Au.

[0046] In the first embodiment, the condition for transitioning from the normal operation mode or the output limited mode to the charging mode is that the level of the sound signal Au remains below the threshold level Lth1 for a certain period of time. However, the present invention is not limited to this, and the mode may be configured to transition immediately to the charging mode without continuing the state for a certain period of time if the level of the sound signal Au is below the threshold level Lth1. Furthermore, the condition for transitioning to the charging mode may be that the level of the sound signal Au is below the threshold level Lth1 (or this state continues for a certain period of time) and that the remaining amount of the secondary battery 206 is below a threshold remaining amount Bth2. That is, if the level of the sound signal Au is below the threshold level Lth1 and the remaining battery amount is below the threshold remaining amount Bth2, the mode may transition to the charging mode, but if the remaining battery amount is equal to or greater than the threshold remaining amount Bth2, the mode may not transition to the charging mode. With this configuration, even if the level of the sound signal Au is below the threshold level Lth1, the mode will not transition to the charging mode if the remaining battery amount is equal to or greater than the threshold remaining amount Bth2 (i.e., if the remaining battery amount is sufficient to a certain extent). This reduces the number of times the battery is charged, thereby preventing deterioration of the secondary battery 206. The threshold remaining capacity Bth2 may be set to an amount that indicates, for example, that the battery remaining capacity is 10%, similar to the threshold remaining capacity Bth1, but may also be set to an amount different from the threshold remaining capacity Bth1 in order to prevent deterioration of the secondary battery 206.

[0047] In the first embodiment, if the voltage Vin is equal to or greater than the threshold voltage Vth1, it is determined that the total power consumed by the sound signal output device 20a has exceeded the threshold power. However, it may be determined based on a factor other than the voltage Vin. As described above, the total power consumed by the sound signal output device 20a can be divided into the power consumed by the power amplifier 214 and the power consumed within the system, and the power consumed by the power amplifier 214 varies depending on the level of the sound signal Au. In other words, by detecting the level of the sound signal Au, the total power consumed by the sound signal output device 20a can be estimated.

[0048] Therefore, if the level of the sound signal Au is equal to or greater than the threshold level Lth2, it may be determined that the total power consumed by the sound signal output device 20a exceeds the threshold power. The threshold level Lth2 is a level used as a criterion for determining whether the total power consumed by the sound signal output device 20a has exceeded the threshold power. For example, the level of the sound signal Au corresponding to when the voltage Vin is equal to the threshold voltage Vth1 may be set as the threshold level Lth2.

[0049] Furthermore, if the voltage Vin is equal to or higher than the threshold voltage Vth2, the control unit 250 may cause the charging unit 204 to charge the secondary battery 206. In other words, if there is a margin in the voltage Vin, the secondary battery 206 may be configured to be used as a power source for the power amplifier 214 while being charged. In this configuration, since it is preferable that the power consumed by the power amplifier 214 is small, the charging conditions for the secondary battery 206 may be such that the level of the sound signal Au is less than a threshold level (e.g., threshold level Lth1) in addition to the voltage Vin being equal to or greater than the threshold voltage Vth2. The threshold voltage Vth2 is set to a voltage that can be used as a power source for the power amplifier 214 while charging the secondary battery 206 with the voltage Vin. In addition, the condition for transitioning from the normal operation mode or the output limiting mode to the charging mode was that the level of the sound signal Au was below the threshold level Lth1 (or this state continued for a certain period of time), but the configuration may also be such that transition to the charging mode occurs if the voltage Vin is equal to or higher than the threshold voltage Vth2.

[0050] Next, a sound signal output device 20b according to a second embodiment and a sound signal output device 20c according to a third embodiment will be described in order.

[0051] 8 is a block diagram showing the configuration of a system 1 including a sound signal output device 20b according to the second embodiment. The sound signal output device 20b differs from the sound signal output device 20a according to the first embodiment in that the switching unit 210a is replaced with a switching unit 210b, the voltage monitoring unit 202 is not included, and the control unit 250 does not output a signal Se1.

[0052] In the second embodiment, the switching unit 210b is a so-called diode OR circuit. In detail, the switching unit 210b includes a diode D1 whose forward direction is from the input jack into which the output plug of the AC adapter 10 is inserted toward the power supply input terminal Pin of the power amplifier 214, and a diode D2 whose forward direction is from the output terminal of the secondary battery 206 toward the power supply input terminal Pin. In the switching unit 210b, if the voltage Vin input from the AC adapter 10 is higher than the voltage Vb output from the secondary battery 206, the voltage Vin becomes the power source for the power amplifier 214, and if the voltage Vb is higher than the voltage Vin, the voltage Vb becomes the power source for the power amplifier 214.

[0053] In this way, the switching unit 210b automatically switches the power source of the power amplifier 214 depending on whether the voltage Vin or the voltage Vb is high or low. Therefore, in the second embodiment, the voltage monitoring unit 202 that monitors the voltage Vin is not necessary, and the configuration can be simplified compared to the first embodiment. Furthermore, in the second embodiment, the power consumed by the voltage monitoring unit 202 and the power consumed in the configuration of the control unit 250 that outputs the signal Se1 in accordance with the signal Vd are reduced, and therefore the power consumed within the system can be reduced accordingly compared to the first embodiment.

[0054] 9 is a block diagram showing the configuration of a system 1 including a sound signal output device 20c according to the third embodiment. The sound signal output device 20c differs from the sound signal output device 20a according to the first embodiment in that it includes a DC / DC converter 201 that converts the voltage Vin and applies it to a charging unit 204 and one end of a switching unit 210a, a DC / DC converter 209 that converts the voltage selected by the switching unit 210a and applies it to a power supply input terminal Pin of a power amplifier 214, and a control unit 250 that outputs a signal Dc.

[0055] The DC / DC converter 201 converts the voltage Vin input from the AC adapter 10 into a charging voltage for the secondary battery 206. The DC / DC converter 201 stops the voltage conversion operation in accordance with the instruction of the signal Dc. The DC / DC converter 209 converts the voltage selected by the switch 210a into a power supply voltage for the power amplifier 214 and applies it to the power supply input terminal Pin. When the control unit 250 selects the secondary battery 206 as the power source for the power amplifier 214, it outputs a signal Dc to the DC / DC conversion unit 201 to instruct it to stop the conversion operation.

[0056] According to the third embodiment, even if the voltage Vin input from the AC adapter 10 and the charging voltage to the secondary battery 206 are different, the voltage conversion by the DC / DC converter 201 can be performed. Furthermore, even if the voltage Vin input from the AC adapter 10 or the voltage Vb output from the secondary battery 206 differs from the power supply voltage of the power amplifier 214, the voltage can be converted by the DC / DC converter 209. Therefore, a wide variety of types of AC adapters 10 and secondary batteries 206 can be used. Furthermore, in the third embodiment, when the power source of the power amplifier 214 is the secondary battery 206, the DC / DC conversion unit 201 stops the voltage conversion operation in accordance with the instruction of the signal Dc, so that the power consumed by the DC / DC conversion unit 201 can be reduced.

[0057] In the third embodiment, the DC / DC conversion unit 209 is configured to constantly perform the voltage conversion operation, but the voltage conversion operation may be stopped in the charging mode. That is, the DC / DC conversion unit 209 may stop the voltage conversion operation in accordance with an instruction of a predetermined signal from the control unit 250. With this configuration, the power consumed by the DC / DC conversion unit 209 when the mode is switched to the charging mode can be reduced, and the saved power can be used to charge the secondary battery 206.

[0058] The above-described first to third embodiments (hereinafter referred to as "embodiments, etc.") can be modified or applied in various ways as follows. Specific modified aspects that can be applied to the embodiments are exemplified below. Two or more aspects arbitrarily selected from the following examples may be combined to the extent that they are not mutually contradictory.

[0059] FIG. 10 is a block diagram showing the configuration of a system 1 including a sound signal output device 20d according to a modified example. The sound signal output device 20d is an example in which the sound signal output device 20a according to the first embodiment has a function of indicating the remaining charge of the secondary battery 206 to the user. The sound signal output device 20d is provided with an LED 260 that is visible to the user, and the control unit 250 controls the light emission mode of the LED 260 using a signal Lec in accordance with the remaining battery level indicated by a signal Bd. The LED 260 can emit light in, for example, red, blue, or green.

[0060] FIG. 11 is a diagram showing the light color and blinking cycle of the LED 260 according to the remaining battery power. By visually checking the LED 260, the user can easily ascertain the current operation mode of the sound signal output device 20d as well as the remaining charge of the secondary battery 206. For example, when the sound signal Au is being emitted from the speaker 30, it is difficult for the user to ascertain whether the current operation mode is the normal operation mode or the limited output mode by listening to the sound alone. On the other hand, by visually checking the LED 260, the user can easily ascertain that if the LED 260 is flashing red, the current operation mode is the limited output mode, and if the LED 260 is lit in any other manner, the current operation mode is the normal operation mode. Note that, although Figure 10 shows an example in which the LED 260 is provided in the sound signal output device 20a according to the first embodiment, the LED 260 may also be provided in the sound signal output device 20b according to the second embodiment or the sound signal output device 20c according to the third embodiment.

[0061] In the embodiment, the secondary battery 206 is charged in the output limit mode or the charging mode. Specifically, the secondary battery 206 is charged when the level of the sound signal Au is equal to or greater than the threshold level Lth1 and the remaining charge of the secondary battery 206 is less than the threshold remaining charge Bth1, or when the level of the sound signal Au remains below the threshold level Lth1 for a certain period of time. This is not limiting, and for example, the control unit 250 may be configured to cause the charging unit 204 to charge the secondary battery 206 if the voltage Vin is equal to or greater than the threshold voltage Vth2 based on the signal Vd. In this configuration, the charging condition for the secondary battery 206 may further include the voltage Vin being equal to or greater than the threshold voltage Vth2, and the level of the sound signal Au being less than the threshold level Lth1, or the level of the sound signal Au remaining below the threshold level Lth1 for a certain period of time.

[0062] In the first or third embodiment, the voltage monitoring unit 202 is configured to monitor the voltage applied to the jack of the sound signal output device 20a, but the present invention is not limited to this configuration. For example, although not particularly shown, the voltage monitoring unit 202 may be configured to monitor the voltage applied to the power supply input terminal Pin of the power amplifier 214. The control unit 250 may determine whether the voltage is equal to or greater than a predetermined threshold voltage, and based on the determination result, may select the voltage Vin input from the AC adapter 10 or the voltage Vb of the secondary battery 206 as the power source for the power amplifier 214 (i.e., the voltage applied to the power supply input terminal Pin). In a configuration in which the voltage monitoring unit 202 monitors the voltage applied to the power input terminal Pin, the power supply voltage of the power amplifier 214 can be accurately detected without being affected by voltage drops due to the switching unit 210a or wiring resistance. As described above, the power consumed by elements other than the power amplifier 214 is approximately constant, so the threshold voltage for the power supply voltage of the power amplifier 214 can be set based on the rated output power of the AC adapter 10 and the power consumed by elements other than the power amplifier 214. In this case, the control unit 250 can accurately select the power source for the power amplifier 214 based on the accurately detected power supply voltage of the power amplifier 214. Furthermore, even if the voltage monitoring unit 202 is configured to monitor the voltage applied to the power supply input terminal Pin, if the voltage at the power supply input terminal Pin is corrected by the amount of voltage drop due to the switching unit 210a and wiring resistance, it is also possible to detect the voltage Vin input from the AC adapter 10. The control unit 250 may compare the voltage Vin detected in this manner with the threshold voltage Vth1.

[0063] From the above description, preferred aspects of the present disclosure can be understood, for example, as follows.

[0064] A sound signal output device according to one aspect 1 of the present disclosure includes a charging unit that controls charging of a secondary battery using input power from an external power source, and a switching unit that switches the power source of an amplifier that amplifies a sound signal between the external power source and the secondary battery, and when the power source is switched to the external power source and the input power exceeds a predetermined power due to an increase in power consumption in the amplifier, the switching unit switches the power source from the external power source to the secondary battery.

[0065] According to the sound signal output device of aspect 1, when the power source of the amplifier unit is an external power source, when the input power exceeds a predetermined power due to an increase in power consumption in the amplifier unit, the power source is switched from the external power source to a secondary battery, so that the amplification of the sound signal can be continued without interruption. The AC adapter 10 is an example of an "external power source," and the power amplifier 214 is an example of an "amplifier." "Input power" refers to the power input from the external power source to the sound signal input device, and includes not only the power consumed by the amplifier, but also the power consumed by elements other than the amplifier. "Specified power" refers to, for example, a threshold power, which is power equivalent to the rated output power of the "external power source." However, since an error is allowed for in the rated output power, the "specified power" is the power that takes error into account in the rated output power of the "external power source."

[0066] In the sound signal output device according to a second specific aspect of the first aspect, when the external power supply is disconnected or abnormal, the switching unit selects the secondary battery as the power source. According to the sound signal output device of the second aspect, even when the external power supply is not connected or is not normal, the sound signal can be continuously amplified. Note that "when not connected" refers to a case where the external power supply is not connected to the sound signal output device, and "when abnormal" refers to a case where a malfunction has occurred, for example, when the external power supply is connected to the sound signal output device but the external power supply is not outputting at its rated capacity.

[0067] A sound signal output device according to a specific aspect 3 of aspect 1 further includes a monitoring unit that monitors the input voltage from the external power source, and a control unit that controls the switching of the power source by the switching unit in accordance with the input voltage monitored by the monitoring unit, and when the voltage monitored by the monitoring unit is less than a first voltage, the control unit determines that the input power has exceeded the predetermined power, and controls the switching unit to switch the power source from the external power source to the secondary battery. According to the sound signal output device of aspect 3, when the input voltage is less than the first voltage, it is determined that the input power has exceeded the predetermined power. Note that the threshold voltage Vth1 is an example of the "first voltage."

[0068] In a sound signal output device according to a specific aspect 4 of aspect 3, the first voltage is less than the lower limit of the rated output voltage of the external power supply and is equal to or greater than the voltage at which a protection circuit built into the external power supply operates. The "lower limit of the rated output voltage" refers to the lower limit of the voltage range that an external power supply can stably output. For example, if the rated output voltage is 24V ±5%, the lower limit of the rated output voltage is 23.4V. The "protection circuit" is a circuit that cuts off the output of an external power supply to protect the external power supply, and is built into the external power supply. The external power supply may be of a type that has a time lag before the protection circuit operates in order to withstand temporary overload, or that has a heat sink to dissipate temporary heat generation, but is not limited to these types.

[0069] A sound signal output device according to a specific aspect 5 of aspect 1 further includes a level detection unit that detects the level of the sound signal, and a control unit that controls the charging unit in accordance with the level detected by the level detection unit, and when the level detected by the level detection unit is less than a first level, the control unit controls the charging unit to charge the secondary battery. According to the sound signal output device of aspect 5, when the level of the sound signal is lower than the first level, the secondary battery is charged. The threshold level Lth1 is an example of the "first level."

[0070] A sound signal output device according to a specific embodiment 6 of embodiment 1 further includes a remaining capacity detection unit that detects the remaining capacity of the secondary battery, and an attenuation unit that attenuates the sound signal and inputs it to the amplifier unit when the remaining capacity detected by the remaining capacity detection unit is less than a first amount. According to the sound signal output device of the sixth aspect, when the remaining charge of the secondary battery is less than a first amount, the sound signal is attenuated and input to the amplifier, so that the amplification of the sound signal can be continued without interruption and the power consumed by the amplifier can be reduced. The threshold remaining charge Bth1 is an example of the "first amount."

[0071] A sound signal output device according to a specific aspect 7 of aspect 6 further includes a control unit that controls the charging unit in accordance with the remaining amount detected by the remaining amount detection unit, and when the remaining amount detected by the remaining amount detection unit is less than the first amount, the control unit controls the charging unit to charge the secondary battery. According to the sound signal output device of the seventh aspect, when the remaining charge of the secondary battery is less than the first amount, the secondary battery is charged.

[0072] A sound signal output device according to a specific embodiment 8 of embodiment 1 further includes a level detection unit that detects the level of the sound signal, and a control unit that controls the switching of the power source by the switching unit according to the level detected by the level detection unit, and the control unit determines that the input power has exceeded the predetermined power when the level detected by the level detection unit is equal to or higher than a second level. According to the sound signal output device of aspect 8, it is possible to continue amplifying the sound signal even when the level of the sound signal is equal to or higher than the second level. The threshold level Lth2 is an example of the "second level".

[0073] A sound signal output device according to a specific aspect 9 of aspect 1 further includes a level detection unit that detects the level of the sound signal, a remaining charge detection unit that detects the remaining charge of the secondary battery, and a control unit that controls the charging unit in accordance with the level detected by the level detection unit and the remaining charge detected by the remaining charge detection unit, and when the level detected by the level detection unit is less than a first level, if the remaining charge detected by the remaining charge detection unit is less than a second amount, the control unit controls the charging unit to charge the secondary battery, and if the remaining charge is equal to or greater than the second amount, the control unit controls the charging unit to not charge the secondary battery. According to the sound signal output device of aspect 9, when the level of the sound signal is below the first level, if the remaining charge of the secondary battery is less than a second amount, the secondary battery is charged, and if the remaining charge is equal to or greater than the second amount, the secondary battery is not charged. In other words, even if the level of the sound signal is below the first level, if the remaining charge of the secondary battery is equal to or greater than the second amount, charging of the secondary battery is suppressed, thereby preventing deterioration of the secondary battery. The threshold remaining charge Bth2 is an example of the "second amount."

[0074] A specific example 10 of the sound signal output device of example 1 further includes a monitoring unit that monitors the input voltage from the external power source, and charges the secondary battery when the input voltage monitored by the monitoring unit is equal to or higher than a second voltage. According to the sound signal output device of aspect 10, the secondary battery is charged when the input voltage from the external power supply is equal to or higher than the second voltage. The threshold voltage Vth2 is an example of the "second voltage."

[0075] The sound signal output device according to aspect 1 can be understood as the following sound signal output method: That is, the sound signal output method according to aspect 11 controls charging of a secondary battery with input power from an external power source, and when switching the power source of an amplifier that amplifies a sound signal to either the external power source or the secondary battery, if the power source is switched to the external power source and the input power exceeds a predetermined power due to an increase in power consumption in the amplifier, the power source is switched from the external power source to the secondary battery. [Explanation of symbols]

[0076] 10...AC adapter, 20a, 20b, 20c, 20d...sound signal output device, 30...speaker, 202...voltage monitoring unit, 204...charging unit, 206...secondary battery, 208...remaining charge detection unit, 214...power amplifier, 210a, 210b...switching unit, 216...level detection unit 212, 220...attenuation unit, 250...control unit.

Claims

1. a charging unit that controls charging of the secondary battery using input power from an external power supply; a switching unit that switches the power source of an amplifier that amplifies a sound signal between the external power supply and the secondary battery; and The switching unit is When the power source is switched to the external power source, if the input power exceeds a predetermined power due to an increase in power consumption in the amplifier unit, the power source is switched from the external power source to the secondary battery. Sound signal output device.

2. When the external power supply is not connected or is abnormal, The switching unit is The power source is the secondary battery. The sound signal output device according to claim 1 .

3. a voltage monitoring unit that monitors an input voltage from the external power supply; a control unit that controls the switching unit to switch the power source in accordance with the input voltage monitored by the voltage monitoring unit; and The control unit When the voltage monitored by the voltage monitoring unit is lower than a first voltage, it is determined that the input power has exceeded the predetermined power, and the switching unit is controlled to switch the power source from the external power supply to the secondary battery. The sound signal output device according to claim 1 .

4. The first voltage is A voltage that is less than the lower limit of the rated output voltage of the external power supply, but is equal to or greater than the voltage at which a protection circuit built into the external power supply operates. The sound signal output device according to claim 3 .

5. a level detection unit that detects the level of the sound signal; a control unit that controls the charging unit in accordance with the level detected by the level detection unit; and The control unit When the level detected by the level detection unit is lower than a first level, the charging unit is controlled to charge the secondary battery. The sound signal output device according to claim 1 .

6. a remaining capacity detection unit that detects a remaining capacity of the secondary battery; an attenuation unit that attenuates the sound signal and inputs the attenuated sound signal to the amplifier unit when the remaining amount detected by the remaining amount detection unit is less than a first amount; Further having The sound signal output device according to claim 1 .

7. a control unit that controls the charging unit in accordance with the remaining amount detected by the remaining amount detection unit; and The control unit When the remaining amount detected by the remaining amount detection unit is less than the first amount, the charging unit is controlled to charge the secondary battery. The sound signal output device according to claim 6 .

8. a level detection unit that detects the level of the sound signal; a control unit that controls the switching unit to switch the power source in accordance with the level detected by the level detection unit; and The control unit When the level detected by the level detection unit is equal to or higher than a second level, it is determined that the input power has exceeded the predetermined power. The sound signal output device according to claim 1 .

9. a level detection unit that detects the level of the sound signal; a remaining capacity detection unit that detects a remaining capacity of the secondary battery; a control unit that controls the charging unit in accordance with the level detected by the level detection unit and the remaining amount detected by the remaining amount detection unit; and The control unit When the level detected by the level detection unit is less than a first level, if the remaining amount detected by the remaining amount detection unit is less than a second amount, controlling the charging unit to charge the secondary battery; If the remaining amount is equal to or greater than the second amount, the charging unit is controlled to stop charging the secondary battery. The sound signal output device according to claim 1 .

10. a voltage monitoring unit that monitors the input voltage from the external power supply; and When the input voltage monitored by the voltage monitoring unit is equal to or higher than a second voltage, the secondary battery is charged. The sound signal output device according to claim 1 .

11. Controlling the charging of the secondary battery using input power from an external power source; When switching the power source of an amplifier that amplifies a sound signal to either the external power source or the secondary battery, When the power source is switched to the external power source, if the input power exceeds a predetermined power due to an increase in power consumption in the amplifier unit, the power source is switched from the external power source to the secondary battery. Sound signal output method.

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