JP6115266B2 - Communication device - Google Patents

Description

  The present invention relates to a communication apparatus that can be used as an emergency call system and performs a call via a radio base station.

As an emergency call system mounted on a vehicle, there is one that includes a communication device such as a hands-free telephone device or a handset telephone device, and can make a call with a facility outside the vehicle.
When such a communication device is used in the event of a traffic accident or vehicle failure, the power supply from the main power supply may stop due to damage to the main battery, which is the main power supply, or disconnection of the power supply line. There is sex. In view of such a situation, an auxiliary battery is provided for such a case, and when the power supply from the main battery cannot be performed, the auxiliary battery is configured to supply the power.

  If the auxiliary battery is made large, it is not preferable from the viewpoint of the degree of freedom of arrangement of the apparatus and the cost. Therefore, there is a demand for using an auxiliary battery having a capacity as small as possible. Conventionally, an emergency call system has been proposed that reduces the current consumption during a call by limiting the current to a speaker amplifier that amplifies an audio signal (see Patent Document 1).

JP 2008-98706 A

  In order to employ a small auxiliary battery, it is preferable to make it possible to use an auxiliary battery with a small maximum supply current by reducing the maximum current consumption of the entire communication device. For this purpose, the communication device may be configured to be able to suppress an increase in maximum current consumption.

  An object of the present invention is to provide a communication device capable of suppressing an increase in maximum current consumption.

One aspect of the present disclosure relates to a communication device (11) that performs a call with a partner via a wireless base station.
In this communication apparatus, a first audio signal, which is an audio signal input from a microphone (21), is acquired, and a transmission means (33) is used as a radio base station for transmitting radio waves obtained by modulating and superimposing the acquired first audio signal. Send to the station. Also, the second radio signal is generated by demodulating the received radio wave received from the radio base station.

  The first determination means (31) determines the presence or absence of sound input to the microphone based on the sound signal level of the first sound signal, and the second determination means (31) is the sound signal of the second sound signal. The presence / absence of voice input at the destination is determined based on the level.

  Then, at least a current supplied to at least one of the current supplied to the transmitting means and the current supplied to the amplifying means for inputting and amplifying the generated second audio signal. A current reduction operation is performed to reduce the current. This current reduction operation is executed when the first determination means determines that there is a voice input and the second determination means determines that there is a voice input.

  The state in which the first determination unit and the second determination unit determine that there is a voice input is a state in which voice is input from the microphone and the other party's voice is output from the speaker. The communication device consumes a large amount of current for the operation of superimposing the input sound input from the microphone on the transmission radio wave and the operation of amplifying the output sound output to the speaker. It is highly possible that the state in which the peak is in the state described above.

  Since the communication device of the present invention reduces the current consumption of any one of the above-described states, an increase in the maximum current consumption can be suppressed. Thereby, for example, a battery having a small maximum supply current can be adopted as an auxiliary battery for supplying power to the communication device, and the auxiliary battery and the communication device as a whole can be reduced in size and the degree of freedom in installing the communication device can be increased. .

Note that the above-described microphone and speaker may be connected to the communication device, or may be provided in the communication device.
Note that the reference numerals in parentheses described in this column and in the claims indicate the correspondence with the specific means described in the embodiment described later as one aspect, and the technical scope of the present invention. It is not limited.

It is a block diagram which shows the structure of the emergency call system of Example 1. FIG. It is a circuit diagram which shows a current limiting circuit, (A) is a schematic diagram which shows a connection relationship, (B) is an example of a concrete circuit configuration, and the relationship between the output current and output voltage in the circuit configuration It is a graph which shows. It is a figure explaining an example of control which reduces current consumption. It is a block diagram which shows the structure of the modification of an emergency call system. It is a graph which shows the structural example of an amplitude limiting circuit, and the relationship between the input voltage and output voltage of the amplitude limiting circuit. It is a flowchart which shows the process sequence of the consumption current reduction process in the case of giving priority to transmission. It is a flowchart which shows the process sequence of the consumption current reduction process in the case of giving priority to reception. It is a block diagram which shows the structure of the emergency call system of Example 2. FIG. (A) is a graph which shows the example of the frequency characteristic of the impedance of a speaker, (B) is a graph which shows the output voltage of the speaker amplifier which can reduce the consumption current in the speaker at the time of an operation mode. It is a graph which shows the structural example of a low frequency component cut circuit, and the relationship between a frequency and a gain.

Embodiments of the present invention will be described below with reference to the drawings.
[Example 1]
(1) Configuration of Emergency Call System The emergency call system 1 of this embodiment is a system that is mounted on a vehicle and used. As shown in FIG. 1, a communication device 11, an antenna 13, a main battery 15, and a backup battery 17 are used. , An emergency switch 19, a microphone 21, a speaker 23, an airbag ECU 25, a temperature sensor 27, and the like.

  The emergency call system 1 makes a call with a communication partner 11 via a wireless base station (not shown). The wireless base stations here are scattered radio wave transmission / reception facilities having antennas. The communication device 11 communicates with a radio base station when located in a communicable range of the radio base station, and mutually establishes a telephone line with a communication partner via a communication network that connects the radio base stations and other exchange facilities. Connect to make a call.

The antenna 13 is used for transmission / reception of radio waves with the radio base station.
The main battery 15 is a battery used for starting the engine of the vehicle and supplying power to electrical components. The backup battery 17 (hereinafter simply referred to as BUB 17) is a small auxiliary battery having a small current capacity that can be supplied as compared with the main battery 15. The main battery 15 and the BUB 17 supply power to the communication device 11.

  The emergency switch 19 is a switch that is pressed by the user in an emergency such as a vehicle failure or an accident, and is used to switch the communication device 11 to an operation mode described later. The microphone 21 inputs the sound in the vehicle and outputs a sound signal to the communication device 11. The speaker 23 outputs sound into the vehicle based on the sound signal output from the communication device 11.

  The airbag ECU 25 is an electronic control unit that controls the operation of the airbag. When the airbag is in an operating state, the airbag ECU 25 outputs an airbag operation signal to the communication device 11 for the purpose of notifying that the airbag has been operated. .

The temperature sensor 27 is a sensor attached to the BUB 17 and outputs temperature information of the BUB 17 to the communication device 11.
The communication device 11 includes a control unit 31, a radio unit 33, a power supply switching control unit 35, a current consumption suppression circuit unit 37, a speaker amplifier (SPAMP) 39, and the like.

  The control unit 31 is configured around a known microcomputer including a CPU 31a, a ROM 31b, a RAM (not shown), an I / O, a bus line connecting these components, and the like, and controls the entire communication device 11 described above. . Further, the control unit 31 executes a process specific to the present invention, which will be described later, according to the application program stored in the ROM 31b.

  The control unit 31 functions as a codec 31c having a codec (CODEC) function. The codec 31c may have a configuration in which the CPU 31a realizes a function by application software stored in the ROM 31b, or may have a configuration including a chip having a codec function.

  The radio unit 33 demodulates the high frequency received radio wave received from the radio base station, generates a digital signal, and outputs the digital signal to the control unit 31. This high-frequency received radio wave is a radio wave transmitted from the communication device at the other end of the call and on which the audio signal at the other end is superimposed. The control unit 31 generates an audio signal (an example of the second audio signal in the present invention) from the input digital signal.

  Further, the control unit 31 obtains an audio signal (an example of the first audio signal in the present invention) input from the microphone 21 and generates a digital signal, and the radio unit 33 modulates the digital signal and superimposes the radio frequency transmission radio wave. Is generated and transmitted to the radio base station. Radio wave transmission control of the radio unit 33 is performed according to a control signal output from the control unit 31.

  The power supply switching control unit 35 switches the supply source of power supplied to the communication device 11 to either the main battery 15 or the BUB 17. Normally, power is supplied from the main battery 15 to the communication device 11, but when a control signal for switching to the BUB 17 is input from the control unit 31, the power supply source is switched to the BUB 17.

  The power supply switching control unit 35 outputs the voltage value of the power supplied from the main battery 15 to the control unit 31. When the voltage value falls below a predetermined threshold in the operation mode described later, the control unit 31 outputs a control signal indicating that the power supply source is switched to the BUB 17.

  In FIG. 1, a broken line indicates a power supply path. Although description of power supply to other than the speaker amplifier 39 is omitted, power is also supplied from the power supply switching control unit 35 to the control unit 31, the radio unit 33, and the like.

  The consumption current suppression circuit unit 37 is provided between the power supply switching control unit 35 and the speaker amplifier 39. In normal times, power is supplied from the main battery 15 and power is supplied to the speaker amplifier 39 without any special restriction. On the other hand, when a predetermined condition is satisfied, power is supplied to the speaker amplifier 39 by switching to a current limiting circuit that limits current supply based on a control signal from the control unit 31.

As a specific configuration of the current limiting circuit, various types such as a DC / DC converter and a resistance circuit can be applied. An example of the current limiting circuit will be described with reference to FIGS.
FIG. 2A is a schematic circuit diagram showing the configuration except for the BUB 17, the current limiting circuit 38, and the speaker amplifier 39. The current supplied from the BUB 17 is supplied to the speaker amplifier 39 via the current limiting circuit 38.

  A specific example of the current limiting circuit 38 is shown in FIG. Tr1 operates in the direction of OFF (OFF) → ON (ON) when a current exceeding a certain value flows through R1, and Tr2 operates in the direction of ON → OFF in order to short-circuit between BE of Tr2. , No more current flows (the output current is limited). Therefore, the upper limit of the current supply amount to the speaker amplifier 39 is determined.

  The speaker amplifier 39 inputs and amplifies the audio signal generated by the control unit 31 and drives the speaker 23. Note that the speaker amplifier 39 of the present embodiment is an amplifier whose current consumption varies depending on the level of the input audio signal.

(2) Operation of Communication Device The communication device 11 of this embodiment operates in two modes, a stop mode and an operation mode. In the stop mode, upon receiving the power supply from the main battery 15, the control unit 31 detects the pressing signal of the emergency switch 19 and the operation signal from the airbag ECU. When the user presses the emergency switch 19 and when an airbag operation signal is transmitted to the control unit 31, the operation mode is switched.

  In the operation mode, the control unit 31 makes a call to the emergency call center to establish communication so that a vehicle occupant can make a call using the microphone 21 and the speaker 23 with a predetermined emergency call center operator. .

  Further, in the operation mode, the control unit 31 causes the main battery 15 when the voltage value of the power supplied from the main battery 15 is equal to or less than a predetermined threshold, that is, when the charge amount of the main battery 15 is not sufficient, or when the main battery 15 is broken or disconnected. When the power supply from 15 is not received, a control signal is output to the power supply switching control unit 35 to switch the power supply source from the main battery 15 to the BUB 17.

  Then, the control unit 31 determines the presence / absence of voice input (caller's utterance) from the call partner based on the voice signal level of the voice signal generated from the received radio wave received from the radio base station, Based on the input audio signal level, the presence / absence of audio input to the microphone (utterance of the vehicle occupant) is determined. Specifically, for example, it is determined that there is a voice input when the voice input level is equal to or higher than a predetermined threshold or when the voice level is higher than a certain level compared to the noise level.

  Hereinafter, the voice input from the other party is described as “received”, and the state where there is an incoming call is described as “received sound”. Also, the voice input to the microphone is described as “sending”, and the state where there is a transmitting is described as “with transmitting sound”.

  An example of control for reducing current consumption will be described with reference to FIG. In the reception state and the transmission state in the figure, “ON” is the timing when there is a reception sound or the timing when there is a transmission sound.

  In FIG. 3, since both the received sound and the transmitted sound are initially present, both are “ON”. In this case, both current consumption due to transmission of transmission radio waves, that is, current supply to the radio unit 33 and current consumption of the speaker amplifier 39, that is, current supply to the speaker amplifier 39, are generated. Will become bigger.

  Therefore, when both the reception sound and the transmission sound are present, at least one of the reduction of the current supplied to the radio unit 33 and the reduction of the current supplied to the speaker amplifier 39 is executed as the current reduction operation. To do.

(2-1) Reduction of current supplied to radio unit 33 Reduction of current supplied to radio unit 33 is realized by executing one of the following two operations.

(2-1-1) Output Intermittent Operation As shown in FIG. 3, the transmission radio wave is intermittently transmitted as the output intermittent operation. At this time, the audio signal input from the microphone 21 cannot be transmitted, but the connection state with the radio base station can be maintained.

  The radio base station performs control so that communication is not immediately terminated even if a transmission radio wave from a mobile communication terminal such as the communication device 11 is interrupted. This is because the reception of radio waves at the radio base station may be interrupted instantaneously due to the movement of the mobile communication terminal or the like, thereby preventing the communication from being disconnected. Therefore, as described above, the transmission radio wave is transmitted intermittently with an interval (for example, 1 second) at which the radio base station does not disconnect the communication, so that the communication connection state is maintained and the transmission radio wave is transmitted. The current consumption is reduced, and the current supplied to the radio unit 33 is reduced.

  When there is no received sound, the output intermittent operation is stopped, and the audio signal input from the microphone 21 is transmitted to the radio base station. Thereafter, if a reception sound is generated, the output intermittent operation is resumed. By performing such an operation, the peak of current consumption can be reduced without interrupting the received sound from the other party of the call.

(2-1-2) Output Reduction Operation As shown in FIG. 3, the transmission radio wave is transmitted with a small transmission output as the output reduction operation. The output in this case is an output smaller than the transmission output except when it is determined that both the received sound and the transmitted sound are present (hereinafter, this case is described as normal time), and communication with the radio base station The output is such that is maintained.

  The magnitude of the normal transmission output is set, for example, according to the received radio wave intensity from the radio base station, or set based on a command from the radio base station. The transmission output at this time is set to a large output with a margin so that communication is not interrupted. Therefore, even if the margin is removed, there is a low possibility that the connection will be interrupted immediately.

  By reducing the transmission output in this way, it is difficult to stably transmit the voice signal of the transmission to the radio base station as compared with the normal time, but while maintaining the connection state with the radio base station, The current consumption due to the transmission of radio waves is reduced, and the current supplied to the radio unit 33 is reduced.

  When there is no received sound, the output reduction operation is stopped, and the audio signal input from the microphone 21 is transmitted to the radio base station with the normal transmission output. Thereafter, if a reception sound is generated, the output reduction operation is resumed. By performing such an operation, the peak of current consumption can be reduced without interrupting the received sound from the other party of the call.

(2-2) Reduction of current supplied to speaker amplifier 39 Reduction of current supplied to speaker amplifier 39 is realized by executing one of the following two operations.

(2-2-1) Input Current Limit The current supplied to the speaker amplifier 39 by the current limit circuit 38 is limited.
When it is determined that both the received sound and the transmitted sound are present, the control unit 31 outputs a control signal to the current consumption suppression circuit unit 37 to supply a current via the current limiting circuit 38. When the received voice signal level is high, the current consumption of the speaker amplifier 39 increases. However, by limiting the current supply to the speaker amplifier 39, the peak of current consumption can be reduced.

If there is no transmission sound, the restriction on the current supply to the speaker amplifier 39 may be released.
Note that the current supplied to the speaker amplifier 39 may be limited to be substantially zero.

(2-2-2) Input Signal Suppression By cutting the peak of the audio signal in advance before the audio signal is input to the speaker amplifier 39, the current supplied to the speaker amplifier 39 is reduced.

  The control unit 31 (codec 31c) outputs the received voice signal to the speaker amplifier 39 without performing any special processing during normal operation. On the other hand, when it is determined that both the received sound and the transmitted sound are present, the peak of the audio signal output to the speaker amplifier 39 is reduced in advance. Thereby, the current consumed by the speaker amplifier 39 can be reduced.

The input audio signal may be controlled to be substantially zero.
Note that the above-described peak cut processing of an audio signal is not limited to the configuration executed by the codec 31c, and may be configured to perform processing by an analog circuit. FIG. 4 shows a block diagram of the communication device 11a provided with such an analog circuit.

  The communication device 11a includes an amplitude limiting circuit 40. The control unit 31 normally outputs a sound signal directly to the speaker amplifier 39, but outputs a sound signal to the speaker amplifier 39 via the amplitude limiting circuit 40 when it is determined that both the received sound and the transmitted sound are present. To do.

  An example of the amplitude limiting circuit 40 is shown in FIG. When the amplitude of the input voltage exceeds a certain level, D1 and D2 change from OFF to OFF, and the signal voltage input to the speaker amplifier 39 is limited. Therefore, the output power of the speaker amplifier 39 is also limited.

(3) Process by control part 31 The consumption current reduction process performed by the control part 31 (CPU31a) is demonstrated. In order to reduce the maximum value of current consumption in the operation mode, when it is determined that both the received sound and the transmitted sound are present, either the transmitted or received sound is preferentially processed and the other is stopped. Or the output drops.

  Hereinafter, a case where transmission is prioritized and a case where reception is prioritized will be described. Which one of transmission and reception is prioritized is arbitrary and may be switched by a user's input operation or the like, or may be configured to prioritize either one in advance.

(3-1) Current Consumption Reduction Processing when Sending is Prioritized This processing will be described with reference to the flowchart of FIG.
This process is started when the communication device 11 enters the operation mode. In this process, first, it is determined whether or not the BUB 17 is operating (S1). In the present embodiment, the BUB 17 operates when the operation mode is set and power is not supplied from the main battery 15 or is insufficient. If the BUB 17 is not operating (S1: NO), this process ends. If BUB17 is operating (S1: YES), the process proceeds to S2. In FIG. 6, YES and NO are written as Y and N, respectively.

  Next, based on the detection signal of the temperature sensor 27, it is determined whether or not the BUB 17 is below a predetermined temperature (0 ° C. in this embodiment) (S2). If it is not below 0 ° C. (S2: NO), this process is terminated. If it is 0 degrees C or less (S2: YES), a process will transfer to S3.

Next, the transmission / reception level determination process is validated (S3). Here, processing for determining the presence / absence of voice input based on the voice signal levels of the transmission and reception is started.
Next, it is determined whether or not there is a transmission sound (S4). If there is a transmission sound (S4: YES), the process proceeds to S5. If there is no transmitted sound (S4: NO), the process proceeds to S10.

Next, it is determined whether there is an incoming call sound (S5). If there is a received sound (S5: YES), the process proceeds to S6. If there is no received sound (S5: NO), the process proceeds to S9.
Next, current consumption is calculated (S6). Here, the sum of the current transmission output and the speaker amplifier output is calculated. The method is not particularly limited, and for example, the consumption current may be estimated from the voice signal levels of transmission and reception, or the current actually supplied may be monitored.

If the current consumption calculated in S6 is equal to or greater than the specified value (S7: YES), the process proceeds to S8. If the current consumption is not greater than or equal to the specified value (S7: NO), the process proceeds to S9.
Next, the speaker amplifier current reduction process is validated (S8). The determination of YES in S7 means that transmission and reception have occurred and the current consumption has exceeded a specified value. In that case, processing is performed so that the amount of current supplied to the speaker amplifier 39 is reduced. Specifically, either the input current limitation or the input signal suppression described in the above (2-2-1) and (2-2-2) is executed.

  Next, transmission data is transmitted (S9). Here, without limiting the output, the audio signal input from the microphone 21 is superimposed on the transmission radio wave and transmitted to the radio base station. Thereafter, the process returns to S4.

  If it is determined in S4 that there is no transmitted sound, it is determined whether there is a received sound (S10). If there is a received sound (S10: YES), the process proceeds to S11. If there is no received sound (S10: NO), the process proceeds to S16.

Next, current consumption is calculated (S11). Here, the same processing as in S6 is performed.
If the consumption current calculated in S11 is equal to or greater than the specified value (S12: YES), the process proceeds to S13. If it is not greater than the specified value (S12: NO), the process proceeds to S16.

  Next, transmission silence data is created (S13), and transmission output reduction or intermittent transmission processing is performed (S14). Specifically, the output intermittent operation and output described in (2-1-1) and (2-1-2) above are performed without superimposing the audio signal from the microphone 21 on the transmission radio wave to the radio base station. Perform one of the lowering actions.

  The determination of YES in S12 means that there is no transmitted sound but the received sound is large and the current consumption is equal to or greater than a specified value. In that case, by reducing the transmission output, the current consumption as a whole can be reduced without limiting the current supplied to the speaker amplifier 39 and lowering the sound quality.

Next, the speaker amplifier current reduction process is invalidated (S15). Since it is determined in S4 that there is no transmitted sound, the operation of the speaker amplifier 39 is returned to normal.
If it is determined in S10 that there is no received sound, and if it is determined in S12 that the received sound is not equal to or higher than a predetermined specified value, the transmission data is transmitted without any output restriction as in S9 ( S16). Thereafter, the process returns to S4.

(3-2) Current Consumption Reduction Processing When Priority is given to Reception This processing will be described with reference to the flowchart of FIG. In addition, about the point which is performing the process similar to the flowchart of FIG. 6, the same code | symbol is attached | subjected and description of a process is omitted.

  If it is determined in S7 that the current consumption calculated in S6 is equal to or greater than the specified value (S7: YES), transmission silence data is created (S21), and transmission output reduction or intermittent transmission processing is performed (S22). The processing of S21 and S22 is the same processing as S13 and S14 of FIG. Thereafter, the process returns to S4.

  In this process, when there is a transmission sound and a reception sound and the current consumption is equal to or greater than a specified value, the reception is given priority and the transmission output is reduced. By reducing the transmission output, the current consumption as a whole can be reduced without limiting the supply current to the speaker amplifier 39 and lowering the sound quality.

  In addition, when NO is determined in S5 and NO is determined in S7, in other words, when there is no incoming call and when the current consumption is equal to or less than the specified value, the transmission data is transmitted. (S23). Here, as in S9 of FIG. 6, the transmission data is transmitted without any output limitation. Thereafter, the process returns to S4.

  In S12, if it is determined that the consumption current calculated in S11 is equal to or greater than the specified value (S12: YES), the speaker amplifier current reduction process is validated (S24). The determination of YES in S12 means that only an incoming call has occurred and the current consumption is equal to or greater than a specified value. In that case, processing is performed so that the amount of current supplied to the speaker amplifier 39 is reduced. Specifically, either the input current limitation or the input signal suppression described in the above (2-2-1) and (2-2-2) is executed. Thereafter, the process proceeds to S26.

  Also, if NO is determined in S10 and NO is determined in S12, in other words, if no transmission or reception occurs or if the current consumption only for reception is less than the specified value, The speaker amplifier current reduction process is invalidated (S25). Since it is determined in S4 that there is no transmission sound and the current consumption is not equal to or higher than the specified value, the operation of the speaker amplifier 39 is returned to normal. Thereafter, the process proceeds to S26.

Next, as in S23, normal transmission data without any output restriction is transmitted (S26). Thereafter, the process returns to S4.
(4) Effect The communication device 11 according to the present embodiment is in a state where sound is input from the microphone 21 and the sound of the other party is output from the speaker 23, that is, in a state where there is a high possibility that the current consumption will peak. In order to reduce the current consumption of any one of reception and transmission, an increase in the maximum current consumption can be suppressed.

  Thereby, a battery with a small maximum supply current can be adopted as the backup battery 17, and the size of the emergency call system 1 as a whole and the degree of freedom of installation of the communication device 11 and the BUB 17 can be increased.

  Further, by intermittently transmitting the transmission radio wave as the current reduction operation, current consumption at a timing when transmission is not performed can be reduced. Note that, at the timing of transmission, it is necessary to supply a large current instantaneously. Since the time is short, for example, the instantaneous current increase can be averaged by discharging the current from the capacitor. Therefore, it is not necessary to configure the BUB 17 itself to have a large current capacity.

  Further, by reducing the transmission output as the current reduction operation, it is possible to reduce the current consumption as a difference from the normal transmission output. Note that the reduced transmission output does not always have to be constant, and the output may be appropriately changed according to the received radio wave intensity from the radio base station, or the output may be periodically increased or decreased.

  In addition, by restricting the current supply to the speaker amplifier 39, it is possible to suppress an increase in the amount of current supply when receiving a voice signal having a high voice signal level from the other party, and it is possible to receive a call. When the upper limit of the audio signal level of the audio signal input to the speaker amplifier 39 is limited, means for limiting the current supply amount is not necessary.

  In addition, since the current reduction operation is not performed unless the sum of the transmission output and the speaker amplifier output is equal to or greater than the specified value, the transmission and reception are not restricted until there is no need to reduce the current supply. You can make a call.

  Note that the specified value may be a fixed value, but a fluctuating value such that the specified value decreases if the amount of current supplied to related devices such as the control unit 31, the microphone 21, and the speaker 23 is large. It may be. In other words, not only the transmission output and the speaker amplifier output but also the configuration in which the current reduction operation is performed when the total consumption current in the other configurations of the communication device 11 and the emergency call system 1 reaches a predetermined specified value. it can.

  In this embodiment, the current reduction operation is performed only when the BUB 17 is 0 ° C. or lower. The battery is affected by temperature, and the output capacity is greatly reduced when the temperature is low. Therefore, the supply current can be reduced when the battery temperature is low and the output capacity is reduced, and the communication device can be driven for a long time.

  In the present embodiment, the control unit 31 is an example of an audio signal acquisition unit, a first determination unit, a second determination unit, and a calculation unit in the present invention, and the wireless unit 33 is an example of a transmission unit. The wireless unit 33 is an example of a generating unit, the speaker amplifier 39 is an example of an amplifying unit, and the power supply switching control unit 35 is an example of a switching unit in the present invention.

The control unit 31, the current limiting circuit 38, the amplitude limiting circuit 40, and the low frequency component cut circuit 65 are examples of current reducing means.
[Example 2]
In order to reduce the supply current, it is conceivable to reduce the current supplied to the speaker amplifier. However, the current consumption in the speaker amplifier varies depending on the characteristics of the speaker. In the present embodiment, a communication apparatus having an audio output function capable of performing speaker amplifier output in accordance with speaker characteristics will be described. Note that the speaker amplifier of this embodiment is an amplifier whose current consumption varies depending on the level of an input audio signal.

(1) Configuration of emergency call system Since the emergency call system in the second embodiment has the same configuration as the emergency call system 1 in the first embodiment, the description of the same part as in the first embodiment is omitted. Configurations and functions related to the differences will be described below.

  The emergency notification system of this embodiment is characterized in that the output signal of the speaker amplifier 39 is adjusted in accordance with the frequency characteristic of the impedance of the speaker. More specifically, the output signal voltage (received sound of the received sound) that is output from the speaker amplifier is determined for a frequency band that is determined from the impedance characteristics of the speaker and whose impedance is lower than the surrounding frequency band or lower than a predetermined threshold. Amplitude) is configured to be smaller in the frequency band than in other frequency bands.

(2) Specific configuration As an example, the following two configurations may be considered.
(2-1) Output Adjustment by Analog Circuit FIG. 8 shows a configuration of the emergency call system 61 that performs speaker amplifier output adjustment by an analog circuit. The configuration of the communication device 11b is different from the communication device 11 of the first embodiment. Specifically, the current consumption suppression circuit unit 37 is not provided, and the signal component cut circuit unit 63 is provided between the control unit 31 and the speaker amplifier 39.

  The signal component cut circuit unit 63 has two circuits. One is a first circuit that outputs the audio signal from the control unit 31 to the speaker amplifier 39 as it is. The other is a second circuit configured to reduce the output of a frequency with a small impedance (input of an audio signal to the speaker amplifier 39) in accordance with the frequency characteristic of the load impedance of the speaker 23. The signal component cut circuit unit 63 is configured to switch a circuit through which the audio signal output from the control unit 31 passes according to the control signal output from the control unit 31.

  An example of the impedance characteristic of the speaker is shown in FIG. In this exemplified speaker, the impedance at a low frequency is small. Therefore, as shown in FIG. 9B, the supply current can be reduced by reducing the output of the low frequency component in the output signal from the speaker amplifier to the speaker.

  The signal component cut circuit unit 63 normally outputs the audio signal to the speaker amplifier 39 by the first circuit. However, when it is determined that both the received sound and the transmitted sound are present in the operation mode, the control unit Based on the control signal from 31, the second circuit (low frequency component cut circuit) is switched.

  An example of the low frequency component cut circuit is shown in FIG. FIG. 10 is a schematic circuit diagram illustrating a configuration other than the control unit 31, the low frequency component cut circuit 65, and the speaker amplifier 39. The audio signal output from the control unit 31 is supplied to the speaker amplifier 39 via the low frequency component cut circuit 65.

  At a frequency lower than the cut-off frequency fc (= 1 / 2πCR) determined by the values of C and R, the gain of the amplifier is lowered. Since the sound has a large bass energy, the supply current can be reduced by cutting the bass.

(2-2) Output adjustment by control unit 31 In this configuration, the control unit 31 does not have an analog circuit, and the control unit 31 cuts a predetermined frequency band of the audio signal output to the speaker amplifier 39 in advance (the predetermined frequency band Keep the amplitude small). Specifically, for a speaker having the characteristics shown in FIG. 9A, the audio signal output from the control unit 31 is adjusted in advance to a low frequency audio level. Thereby, the current consumed by the speaker amplifier 39 can be reduced.

(3) Processing by Control Unit 31 Also in the present embodiment, the processing can be executed by the current consumption reduction processing similar to that in the first embodiment.

  Specifically, adjustment control of the audio signal output to the speaker amplifier described above is started in S8 of FIG. 6 and S24 of FIG. In S15 of FIG. 6 and S25 of FIG. 7, the adjustment control is stopped. Other processes are the same as those in the first embodiment.

(4) Effect In the communication device 11b of the present embodiment, the signal output from the speaker amplifier 39 can be adjusted in accordance with the characteristics of the speaker 23, and the current consumption in the speaker amplifier 39 can be reduced.

In the present embodiment, the low frequency component is cut according to the characteristics of the speaker. However, the low frequency component may not be used as long as the impedance is low.
Conventionally, for example, the audio signal output from the speaker amplifier has been adjusted for the purpose of improving the ease of hearing of the sound or the preference of the listener, but the adjustment is made according to the frequency characteristics of the speaker impedance. There was no. That is, the above-mentioned invention is a novel technical idea that has not existed before.

[Modification]
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various forms can be taken as long as they belong to the technical scope of the present invention.

  For example, in each of the above-described embodiments, the configuration in which the communication device is used in the emergency call system is illustrated, but the configuration may be used in a communication system other than the emergency call system. Therefore, a configuration in which the operation of reducing the supply current is always performed even when there is no condition such as an emergency or a low temperature, or a configuration in which the operation is performed according to other conditions may be employed.

  Further, in each of the above embodiments, the configuration in which the operation of reducing the supply current is performed when the consumption current is equal to or more than the specified value is illustrated. However, the consumption current is not measured, and the supply current is simply determined based on the presence or absence of transmission and reception. The reduction operation may be performed.

  In each of the above-described embodiments, the configuration in which either one of reception and transmission is prioritized and the current consumed by the other is reduced. However, the consumption current is reduced for both reception and transmission (wireless). The current reduction operation may be simultaneously performed on both the unit 33 and the speaker amplifier 39.

DESCRIPTION OF SYMBOLS 1 ... Emergency call system 11, 11a, 11b ... Communication apparatus, 17 ... Backup battery (BUB), 21 ... Microphone, 23 ... Speaker, 31 ... Control part, 33 ... Radio | wireless part, 35 ... Power supply switching control part, 37 ... Current consumption suppression circuit unit 38 ... Current limiting circuit 39 ... Speaker amplifier 40 ... Amplitude limiting circuit 61 ... Emergency notification system 63 ... Signal component cut circuit unit 65 ... Low frequency component cut circuit

Claims (9)

A communication device (11) for communicating with a partner via a wireless base station,
An audio signal acquisition means (31) for acquiring a first audio signal which is an audio signal input from the microphone (21);
Transmitting means (31, 33) for transmitting a transmission radio wave obtained by modulating and superimposing the first audio signal acquired by the audio signal acquiring means to the radio base station;
Generating means (31, 33) for generating a second audio signal by demodulating the received radio wave received from the radio base station;
First determination means (31, S4) for determining the presence or absence of voice input by the user's utterance to the microphone based on the voice signal level of the first voice signal acquired by the voice signal acquisition means;
Second determination means (31, S5, S10) for determining the presence or absence of voice input by the voice of the other party based on the voice signal level of the second voice signal generated by the generation means;
At least one of the current supplied to the transmitting means and the current supplied to the amplifying means (39) for inputting and amplifying the second audio signal generated by the generating means. Current reduction means (31, 38, 40, 65, S8, S14, S22, S24) for performing a current reduction operation for reducing the supplied current;
The current reduction means performs the current reduction operation when the first determination means determines that there is a voice input and the second determination means determines that there is a voice input. . The communication apparatus according to claim 1, wherein the current reduction unit intermittently transmits the transmission radio wave as the current reduction operation. The current reducing means transmits the transmission radio wave with a smaller transmission output than the normal transmission output except when the first determination means and the second determination means determine that there is a voice input as the current reduction operation. The communication apparatus according to claim 1, wherein: The communication device according to claim 1, wherein the current reduction unit limits current supply to the amplification unit as the current reduction operation. The communication apparatus according to claim 1, wherein the current reduction unit limits an audio signal level of a second audio signal input to the amplification unit as the current reduction operation. As the current reduction operation, the current reduction unit lowers the audio signal level of the second audio signal input to the amplification unit for a frequency band in which the impedance of the speaker from which the amplification unit outputs the audio signal is lower than a predetermined reference The communication device according to claim 1, wherein: A calculating means (31) for calculating a sum of a current amount supplied to the transmitting means and a current amount supplied to the amplifying means;
The current reduction means performs the current reduction operation when the sum of the current amounts calculated by the calculation means is equal to or greater than a predetermined threshold value. Item 1. The communication device according to item 1. The communication device includes a first power source (15) as a power source capable of supplying a current, an auxiliary battery (17) having a smaller current capacity that can be supplied than the first power source,
Switching means (35) for switching the source of current to the communication device from the first power source to the auxiliary battery when a predetermined condition is satisfied,
The current reduction means executes the current reduction operation when the current supply source is switched to the auxiliary battery by the switching means. The communication device described. The communication device according to claim 8, wherein the current reduction unit further performs the current reduction operation when the temperature of the auxiliary battery becomes equal to or lower than a predetermined threshold value.

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