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DESCRIPTION JP2008131478

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DESCRIPTION JP2008131478
[PROBLEMS] A voice of a calling party can be output from a speaker, or an audio signal output
from a small-sized, low-output audio device can be amplified and output from the speaker.
SOLUTION: An external connection terminal to which a mobile phone 2 and an audio device 3
are selectively connected and an audio reception signal at the mobile phone 2 taken in from an
external connection terminal or an audio signal output from the audio device 3 are amplified. A
signal processing circuit 4 including an amplification circuit 41, and a speaker 40 for converting
the amplified output of the amplification circuit 41 into sound and outputting the sound. The
signal processing circuit 4 cuts the low frequency component of the signal taken in from the
external connection terminal to remove the low frequency, and the low frequency removal circuit
5 when the mobile phone 2 is connected to the external connection terminal And a control circuit
6 that deactivates the low frequency elimination circuit 5 when the audio device 3 is connected
to the external connection terminal. [Selected figure] Figure 1
Amplifier with speaker and hands-free device for mobile phones
[0001]
The present invention refers to a voice signal received by a mobile phone (hereinafter referred to
as "voice received signal"). The present invention relates to an amplifier with a speaker that
amplifies the voice of the other party and outputs voice of the other party from a speaker, and a
hands-free device of a mobile phone capable of making a call without holding the mobile phone.
Amplifier with speaker that can be applied to the application of amplifying the audio signal
output from the audio equipment and outputting it from the speaker in addition to the
application of outputting the voice of the speaker from the speaker, and the handsfree of the
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cellular phone in which the amplifier is used It relates to the device.
[0002]
With the spread of mobile phones, calls are being made by mobile phones in running vehicles,
and as a result traffic accidents occur frequently. In particular, when an incoming call is
answered while driving, the user may be inadvertently forward or distracted, which may cause an
accident. Therefore, there has been proposed a hands-free device of a mobile phone which does
not hold the mobile phone in one hand to operate or respond when an incoming call is received
(for example, see Patent Document 1).
[0003]
Unexamined-Japanese-Patent No. 10-224449
[0004]
The hands-free device is a combination terminal of an earphone and a microphone provided in a
mobile phone (hereinafter, simply referred to as a "shared terminal".
The voice reception signal of the mobile phone is taken out from the shared terminal to the
outside and output from the speaker as voice, while the voice signal to be transmitted to the
other party obtained by voice input to the microphone (hereinafter referred to as , "Voice
transmission signal". ) Is supplied to the mobile phone from the shared terminal.
[0005]
The hands-free device of the mobile phone described above can be manufactured inexpensively
by combining existing circuits, but a speaker or a microphone is connected to the shared
terminal and the voice reception signal in the mobile phone is simply amplified. In a simple
configuration in which output is only from the speaker, an echo phenomenon occurs in the
telephone of the other party, making it difficult to hear voice. That is, as a result of the voice of
the other party output from the speaker being mixed with the voice of the transmitter and
collected by the microphone, a phenomenon in which the voice emitted by the other party echoes
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2
like this in the phone of the other party (echo phenomenon) Cause.
[0006]
SUMMARY OF THE INVENTION The present invention has been made focusing on the above
problem, and it has an amplifier with a speaker equipped with a function to suppress the
occurrence of an echo phenomenon in the telephone of the other party when used in a handsfree
device of a mobile phone. An object of the present invention is to provide a hands-free device of a
mobile phone in which the amplifier is used.
[0007]
In addition to the application where the voice of the other party is output from the speaker, the
other object of the present invention is also applied to the application where the audio signal
output from the small-sized, small-output audio device is amplified and output from the speaker
It is an object of the present invention to provide an applicable amplifier with a speaker and a
hands free device of a mobile phone in which the amplifier is used.
[0008]
The amplifier with a speaker according to the present invention is an external connection
terminal to which the mobile phone and the audio device are selectively connected via the
connection cable, and an audio reception signal or audio device in the mobile phone taken in
from the external connection terminal. A signal processing circuit including an amplification
circuit for amplifying an audio signal, and a speaker for converting the amplification output of
the amplification circuit into sound and outputting the sound.
The signal processing circuit is a low frequency removing circuit that removes low frequency
components by cutting low frequency components of a signal acquired from an external
connection terminal, and the low frequency removing circuit when a mobile phone is connected
to the external connection terminal. And a control circuit which is activated and which
deactivates the low frequency removing circuit when an audio device is connected to the external
connection terminal.
[0009]
Here, the "audio device" refers to an audio device such as a digital audio player dedicated to an
earphone without a built-in speaker or a mini radio built in a speaker with a small output.
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[0010]
When the external connection terminal of the speaker amplifier with the above configuration is
connected to the shared terminal of the mobile phone, the voice reception signal of the mobile
phone input from the external connection terminal is taken into the signal processing circuit and
amplified by the amplifier circuit, The amplified output is converted to voice by the speaker and
output, and the voice of the other party in the call can be heard by the speaker.
When a mobile phone is connected to the external connection terminal, the low frequency
removal circuit is activated by the operation of the control circuit.
Since the low frequency component of the voice frequency accounts for 50% or more of the
factor causing the echo phenomenon, the low frequency removal circuit removes the low
frequency component by cutting the low frequency component included in the voice reception
signal in the mobile phone. The occurrence of the echo phenomenon is suppressed. When an
audio device is connected to the external connection terminal, the low frequency removal circuit
is deactivated by the control circuit, so the low frequency component of the audio signal output
from the audio device is not cut, and the bass removal is performed. There is no risk of
deterioration of sound or deterioration of sound quality.
[0011]
In the above-described configuration of the present invention, the "control circuit" can be realized
not only by a dedicated hardware circuit but also by a programmed computer. In a preferred
embodiment, the control circuit includes a semiconductor switch that turns on when it detects
that the mobile phone is in a communicable state (a state where it is connected to the other
party's phone), and turns on the semiconductor switch. The low frequency removal circuit is
activated by the operation, and the low frequency removal circuit is deactivated by the off
operation of the semiconductor switch. The low frequency removing circuit can be constituted
by, for example, a simple circuit in which a capacitor and a resistor are combined, and for
example, low frequency components of 20 to 300 Hz are cut.
[0012]
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In a preferred embodiment of the present invention, as the connection cable, a stereo audio cable
in which one is set to a ground line and two to a signal line is used. In this case, the two signal
lines are respectively connected to the stereo output circuit of the audio signal when connected
to the audio device, and when connected to the mobile phone, the reception circuit of the audio
reception signal and the audio transmission signal It is connected to the transmission circuit.
[0013]
When a portable telephone in a communicable state is connected to the external connection
terminal via the connection cable of this embodiment, the voice reception signal at the mobile
telephone is taken in from the external connection terminal and amplified, and the amplified
output is obtained by the speaker. It is converted to sound and output. In this case, the
transmission circuit of the voice transmission signal is set to a voltage level at which signal
transmission is possible, and the control circuit detects that the portable telephone in a
communicable state is connected to the external connection terminal by the voltage level. Thus,
the low frequency removal circuit is activated. As a result, the low frequency component of the
audio reception signal fetched from the external connection terminal is cut and the bass is
removed. Also, when an audio device is connected to the external connection terminal via the
connection cable of this embodiment, one stereo output of the audio signal is taken in from the
external connection terminal and amplified, and the amplified output is converted to sound by
the speaker Is output. In this case, since the audio signal has a low voltage level, the control
circuit detects that the audio device is connected to the external connection terminal according to
the voltage level of the other stereo output of the audio signal, thereby reducing the low
frequency removal circuit. Is deactivated. As a result, the low frequency component of the audio
reception signal taken in from the external connection terminal is not cut.
[0014]
The hands-free device of the mobile phone according to the present invention comprises the
amplifier with a speaker and the microphone for voice input, and the amplifier with a speaker
receives an audio reception signal from the mobile phone from an external connection terminal.
A sensitivity adjustment circuit is provided to reduce the sensitivity of the microphone when it is
captured. Here, "reducing the sensitivity of the microphone" is to limit the supply to the mobile
phone of the voice transmission signal obtained by the voice input to the microphone to a
predetermined value or zero.
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[0015]
According to this embodiment, when the voice reception signal of the mobile phone is taken in
from the external connection terminal, the sensitivity adjustment circuit lowers the sensitivity of
the microphone, so the voice of the other party to be output from the speaker is collected by the
microphone Supply to the mobile phone as a voice transmission signal is suppressed, and as a
result, occurrence of an echo phenomenon is suppressed in the telephone of the other party.
Since the sensitivity adjustment circuit does not lower the sensitivity of the microphone when the
voice reception signal of the mobile phone is not fetched from the external connection terminal,
the voice of the transmitter is collected by the microphone and sent to the mobile phone as a
voice transmission signal. Supplied.
[0016]
According to the present invention, in addition to the application of outputting the voice of the
other party from the speaker, the present invention can also be applied to the application of
amplifying the audio signal output by the small-sized small output audio device and outputting it
from the speaker It is possible to effectively use one amplifier with speaker. In addition, since the
low frequency elimination circuit is activated when the portable telephone is connected to the
external connection terminal, it is possible to suppress the occurrence of the echo phenomenon
in the telephone of the other party. On the other hand, when the audio device is connected to the
external connection terminal, the low frequency removing circuit is deactivated, so that the
deterioration of the sound due to the removal of the bass is not caused or the sound quality is not
deteriorated.
[0017]
FIG. 1 shows a schematic configuration of a speaker-equipped amplifier 1 according to an
embodiment of the present invention. The amplifier with speaker 1 in the illustrated example is
applied to a hands-free device that can talk via the microphone 20 and the speaker 40 without
holding the mobile phone 2 in hand, and amplifies the audio reception signal at the mobile phone
2 Audio signal output from the small-sized, low-output audio device 3 such as a digital audio
player or mini radio in addition to the original application of outputting the voice of the other
party from the speaker 40 and outputting it from the speaker 40 There is an additional use to
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[0018]
As shown in FIG. 2 and FIG. 3, the speaker-equipped amplifier 1 is provided with a speaker 40 on
one side of a box-shaped main body case 10, and two external connection terminals 11 and 12
provided on one end face of the main body case 10. It is done. The mobile phone 2 is selectively
connected to one external connection terminal 11 via the two connection cables 8 and 9, and the
audio device 3 is selectively connected via the one connection cable 8. The other external
connection terminal 12 is for connecting a headphone. In the figure, reference numeral 13
denotes an operation display lamp.
[0019]
Inside the body case 10, a signal processing circuit 4 including an amplification circuit 41 for
amplifying an audio reception signal of the mobile phone 2 taken in from the external connection
terminal 11 or an audio signal output from the audio device 3 is incorporated. There is. The
amplified output by the amplifier circuit 41 is converted to sound and output from the speaker
40. Although not shown, the battery 100 (shown in FIG. 4) is provided on the other side of the
main body case 10. A battery box with a lid is provided to accommodate the
[0020]
The signal processing circuit 4 cuts the low frequency component of the voice reception signal at
the mobile phone 2 taken in from the external connection terminal 11 to remove low tones, and
calls the external connection terminal 11. Control circuit 6 for activating the low frequency
elimination circuit 5 when the portable telephone 2 in the state is connected and for disabling
the low frequency elimination circuit 5 when the audio device 3 is connected to the external
connection terminal 11 It contains.
[0021]
The speaker-equipped amplifier 1 and the microphone 20 for voice input constitute the handsfree device of the mobile phone. However, the speaker-equipped amplifier 1 receives an audio
reception signal from the mobile phone 2 from the external connection terminal 11. It further
comprises a sensitivity adjustment circuit 7 that reduces the sensitivity of the microphone 20
when it is captured.
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[0022]
The mobile phone 2 incorporates a receiving circuit for receiving an audio signal from a calling
party and a transmitting circuit for sending an audio signal to the calling party, and the earphone
and microphone shared terminal 21 is provided at an appropriate place.
By using the shared terminal 21, audio can be input / output using the external speaker 40 and
the microphone 20 without using the speaker and the microphone built in the mobile phone 2.
The mobile phone 2 has a function of automatically receiving an incoming call from a calling
party, and when using this hands-free device, it is desirable to set the mobile phone 2 to the state
of an automatic incoming call.
[0023]
The amplifier with speaker 1 and the audio device 3 are connected by a first connection cable 8
as shown in FIG. A stereo audio cable is used as the connection cable 8 and three-pole plugs 80,
80 can be connected to the external connection terminal 11 of the amplifier with speaker 1 and
the audio signal output terminal 30 of the audio device 3 at both ends thereof. Are attached
respectively.
[0024]
The amplifier with speaker 1 and the mobile phone 2 are connected via the first connection cable
8 and the second connection cable 9 as shown in FIG. The second connection cable 9 has one
end attached with a flat terminal 90 connectable to the common terminal 21 of the mobile phone
2 and the other end incorporated with a microphone 20, a call receiving switch 21 and a socket
92. The operation unit 91 is attached. The plug 80 of the first connection cable 8 can be
connected to the socket 92 of the operation unit 91.
[0025]
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When the call switch 21 is pressed at the time of call reception, the power is turned on and the
operation display lamp 13 is turned on to enable a call. Note that if the mobile phone 2 is set to
be in an automatic call reception mode, a call can be made without pressing the call reception
switch 21. In addition, when the mobile phone 2 is in the standby state and the call switch 21 is
pressed, it is possible to make a call to the number set in advance by the mobile phone 2.
[0026]
FIG. 4 shows the configuration of a speaker-equipped amplifier 1 according to an embodiment of
the present invention and the configuration of a hands-free device of a mobile phone in which
the amplifier 1 is used. The hands-free device of the illustrated example is comprised of an
amplifier with speaker 1 and first and second connection cables 8 and 9. Connect one plug 80 of
the first connection cable 8 to the external connection terminal 11 of the amplifier with speaker
1 and connect the other plug 80 of the first connection cable 8 to the socket 92 of the second
connection cable 9, The flat terminal 90 of the second connection cable 9 is connected to the
common terminal 21 of the mobile phone 2. In the figure, reference numeral 12 denotes an
external connection terminal for connecting the headphone 22. Reference numerals 20 and 21
denote a microphone incorporated in the operation unit 91 and a call origination / reception
switch.
[0027]
Each of the first and second connection cables 8 and 9 has one ground line E and two signal lines
R and L. The plugs 80 provided at both ends of the first cable 8 have electrode portions 81E,
81R, 81L in which the respective lines are connected. The two signal lines R and L of the first
connection cable 8 are connected to the stereo output circuit of the audio signal when the plug
80 is connected to the audio device 3. When connected to the mobile phone 2 via the second
connection cable 9, the signal line R is connected to the reception circuit of the voice reception
signal, and the signal line L is connected to the transmission circuit of the voice transmission
signal. An audio transmission signal obtained by audio input to the microphone 91 is supplied to
an audio transmission signal transmission circuit via the transmission line L of the second
connection cable 9.
[0028]
The amplifier with speaker 1 processes an external connection terminal 11 to which the first
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connection cable 8 is connected, and an audio reception signal from the mobile phone 2 captured
from the external connection terminal 11 or an audio signal output from the audio device 3 A
signal processing circuit 4 and a sensitivity adjustment circuit 7 for adjusting the sensitivity of
the microphone 20 are provided.
[0029]
The external connection terminal 11 includes three terminals 11E, 11R and 11L, and each of the
external connection terminals 11 is connected to the respective electrode portions 81E, 81R and
81L provided on the plug 80 of the first connection cable 8.
An audio reception signal at the mobile phone 2 and an audio signal output from the audio
device 3 are taken in from the terminal 11R.
[0030]
The signal processing circuit 4 amplifies the audio reception signal of the mobile phone 2 or an
audio signal output from the audio device 3, and cuts low frequency components of the audio
reception signal of the mobile phone 2 to obtain bass. When the low frequency elimination
circuit 5 for elimination and the portable telephone 2 in a communicable state are connected to
the external connection terminal 11, the low frequency elimination circuit 5 is activated and the
audio equipment 3 is connected. And a control circuit 6 for deactivating the circuit 5.
[0031]
The low frequency removing circuit 5 is composed of two capacitors C1 and C2 and one resistor
R1.
The capacitor C1 and the resistor R1 are connected in series to form a voltage dividing circuit.
When the frequency is low, the impedance of the capacitor C1 is large and the output voltage is
low. On the other hand, when the frequency is high, the impedance of the capacitor C1 is small
and the output voltage is high. In this way, the frequency band of 20 to 300 Hz is cut, and the
occurrence of the echo phenomenon and the howling sound can be suppressed.
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[0032]
The output signal b of the low frequency removing circuit 5 is a signal from which low frequency
components are removed and has a sound range necessary for conversation, and is given to the
amplifying circuit 41 through the capacitor C2. The amplification circuit 41 amplifies the output
signal b to generate an audio signal c, and outputs the audio signal c to the speaker 5 and sends
it to the sensitivity adjustment circuit 7.
[0033]
The control circuit 6 is composed of a single transistor TR1 constituting an on / off switch and a
resistor R1 connected to the base of the transistor TR1, and the terminal 11R is connected to the
base of the transistor TR1 via the resistor R2. The voltage extracted by When the mobile phone 2
in a communicable state is connected to the external connection terminal 11 via the first and
second connection cables 8 and 9, the transmission circuit of the voice transmission signal in the
mobile phone 2 can transmit signals. Therefore, the voltage level is applied to the base of the
transistor TR1 through the terminal 11L, and the transistor TR1 is turned on. As a result, the
resistor R1 is used, and the low frequency removing circuit 5 is activated to remove low
frequency components.
[0034]
When the audio device 3 is connected to the external connection terminal 11 via the first
connection cable 8, the voltage level of the audio signal output from the audio device 3 is low, so
the transistor TR 1 does not turn on, It is in the off state. As a result, the resistor R1 is not
utilized, the low frequency removing circuit 5 is deactivated, and the low frequency component is
not removed.
[0035]
When the sensitivity adjustment circuit 7 limits the supply of the voice transmission signal d
obtained by voice input to the microphone 20 to the mobile phone 2 and when the amplification
circuit 41 outputs the voice signal c The control unit 71 is configured to set the signal limiting
unit 70 in the operating state and set the signal limiting unit 70 in the non-operating state when
not outputting the audio signal c.
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[0036]
The signal limiting unit 70 is constituted by a series circuit of a photocoupler 72 and a resistor R
4 and is in parallel with the microphone 20.
When the audio signal c is sent from the amplification circuit 41 to the control unit 71, the
impedance of the series circuit of the photocoupler 72 and the resistor R4 decreases, and the
sensitivity of the microphone 20 decreases. On the other hand, when the audio signal c is not
sent from the amplifier circuit 41 to the control unit 71, the impedance of the series circuit of the
photocoupler 72 and the resistor R4 is increased, and the sensitivity of the microphone 20 is
increased.
[0037]
The control unit 71 includes a rectifier circuit 73 for rectifying the output of the amplifier circuit
41, and a drive circuit 74 for providing the DC output obtained by the rectifier circuit 73 to the
photocoupler 72 through the resistor R3. When the amplifier circuit 41 outputs the audio signal
c, when the DC output obtained by rectifying the audio signal c by the rectifier circuit 73 is given
to the photocoupler 72 by the drive circuit 74, the photocoupler 72 is turned on. . As a result, the
impedance of the series circuit of the photocoupler 72 and the resistor R4 is reduced to be in the
conductive short state, and the supply of the voice transmission signal obtained by the voice
input to the microphone 20 to the mobile phone 2 is limited.
[0038]
When the amplifier circuit 41 does not output the audio signal c, the photocoupler 72 is not
turned on and is turned off. As a result, the impedance of the series circuit of the photocoupler
72 and the resistor R4 is increased to be in the open state, and the voice transmission signal
obtained by the voice input to the microphone 20 is supplied to the transmission circuit of the
mobile phone 2.
[0039]
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The sensitivity adjustment circuit 7 is not limited to the above configuration, and may have a
configuration as shown in FIG. 5, for example. Also in the illustrated example, the signal limiting
unit 70 capable of limiting the supply of the voice transmission signal d obtained by voice input
to the microphone 20 to the mobile phone 2, and the amplification circuit 41 output the voice
signal c. The control unit 71 is configured to set the signal limiting unit 70 in the operating state,
and set the signal limiting unit 70 in the non-operating state when the audio signal c is not
output.
[0040]
In the signal limiter 70 of this embodiment, when the audio signal c is sent to the controller 71
from the amplifier circuit 41, the impedance of the circuit increases and the sensitivity of the
microphone 20 decreases. On the other hand, when the audio signal c is not sent from the
amplification circuit 41 to the control unit 71, the impedance of the circuit is reduced and the
sensitivity of the microphone 20 is increased. The signal limiting unit 70 shown in the figure
includes a transistor TR3, a resistor R5 connected to the base of the transistor TR3, and a
capacitor C3 connected between the collector and the emitter of the transistor TR3. The
impedance of the transistor TR3 is determined by the resistance between the collector and the
emitter of the transistor TR3 and the capacitor C3.
[0041]
The control unit 71 is composed of a transistor TR4 and two resistors R6 and R7 connected to
the base of the transistor TR4. The resistor R 6 is connected to the output side of the amplifier
circuit 41. The collector of the transistor TR4 is connected to the base of the transistor TR3.
When the audio signal c is not sent from the amplification circuit 41, no current flows to the base
of the transistor TR4, and the transistor TR4 is in the off state. When the audio signal c is sent
from the amplification circuit 41, a base current flows to the transistor TR4 via the resistor R6,
and the transistor TR4 is turned on.
[0042]
A positive voltage is always applied to the amplifier circuit 41 and the resistor R5 by the battery
100. Therefore, when the transistor TR4 of the control unit 71 is off, a positive voltage is applied
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to the base of the transistor TR3 of the signal limiting unit 70 via the resistor R5, and the
transistor TR3 is on. As a result, the collector and the emitter of the transistor TR3 become
conductive to reduce the impedance of the signal limiting unit 70, and the voice transmission
signal d obtained by the voice input to the microphone 20 is supplied to the mobile phone 2.
[0043]
On the other hand, when the transistor TR4 of the control unit 71 is in the on state, the collector
and the emitter of the transistor TR4 are conductive, so that the base current does not flow in the
transistor TR3 of the signal limiting unit 70, and the transistor TR3 is turned off. As a result, the
impedance of the signal limiting unit 70 is increased, and the supply of the voice transmission
signal d obtained by the voice input to the microphone 20 to the mobile phone 2 is limited.
[0044]
When the external connection terminal 11 of the speaker amplifier 1 and the common terminal
20 of the mobile phone 2 are connected via the first and second connection cables 8 and 9, the
mobile phone is connected from the external connection terminal 11 The voice reception signal
at 2 is taken into the signal processing circuit 4 and amplified by the amplification circuit 41, and
the voice signal c is converted to voice by the speaker 40 and output, so the voice of the other
party can be heard by the speaker .
[0045]
When the portable telephone 2 is in a communicable state, the transistor TR1 in the control
circuit 6 is turned on to activate the low frequency elimination circuit 5, so that the low
frequency elimination circuit 5 generates an audio reception signal at the portable telephone 2
The low frequency components included are cut to remove the bass.
This suppresses the occurrence of the echo phenomenon.
[0046]
When the audio device 3 is connected to the external connection terminal 11 by the first
connection cable 8, the transistor TR 1 in the control circuit 6 is in the OFF state and the low
frequency removal circuit 5 is deactivated. The low frequency components included in the audio
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signal output by the signal are not cut, and there is no possibility of deterioration of sound or
deterioration of sound quality due to removal of the bass.
[0047]
It is a block diagram which shows schematic structure of the amplifier with a speaker which is
one Example of this invention.
It is explanatory drawing which shows the connection state of an amplifier with a speaker, and a
mobile telephone. It is explanatory drawing which shows the connection state of amplifier with a
speaker, and audio equipment. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is an electric
circuit diagram showing a configuration of an amplifier with a speaker which is an embodiment
of the present invention and a configuration of a handsfree device of a mobile phone. FIG. 10 is
an electric circuit diagram showing a configuration of a hands-free device of a mobile phone in
which a sensitivity adjustment circuit according to another embodiment is used.
Explanation of sign
[0048]
1 Amplifier with speaker 2 Mobile phone 3 Audio equipment 4 Signal processing circuit 5 Low
frequency elimination circuit 6 Control circuit 7 Sensitivity adjustment circuit 8, 9 Connection
cable 11 External connection terminal 20 Microphone 41 Amplifier circuit
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