JP2009159441A - Sound output apparatus, and noise prevention means - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent noise generated from a detachable earphone. <P>SOLUTION: A sound output apparatus is provided with an earphone insertion detection unit and a power supply control unit. The earphone insertion detection unit detects whether an earphone 28 for converting an electric signal generated by an earphone amplifier 25 into a sound is detached or not by using a sensor 30. After detecting the detachment of the earphone 28, the power supply control unit turns off a power supply 20 for supplying power for generating the electric signal to the earphone amplifier 25. By turning off the power supply 20 after detaching the earphone 28, noise generated from the earphone 28 due to the OFF of the power supply 20 can be prevented. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an audio output device and noise prevention measures, and more particularly, to an audio output device and noise prevention measures used when outputting audio from a speaker that can be attached to and detached from a main body.

  There has been known a mobile phone capable of listening to sound using a detachable earphone. In such a mobile phone, it is desired to prevent noise generated from the earphone, and it is desired to reduce current consumption.

  Japanese Patent Laying-Open No. 2003-110441 discloses a pop sound reduction circuit that can significantly reduce the pop sound generated when the power is turned on and off. The pop noise reduction circuit includes a first switch for turning on / off a pulse width modulation amplifier having an output reference voltage as a midpoint potential of an amplitude, a buffer amplifier for generating a DC voltage equal to the output reference voltage, and the buffer The second switch for turning on / off the amplifier, the first switch and the second switch according to the potential of the rising region of the output reference voltage that rises from when the power is turned on or the falling region of the output reference voltage that falls from the time of power off And a control circuit for operating either the pulse width modulation amplifier or the buffer amplifier by turning on and off the switch 2.

  Japanese Patent Application Laid-Open No. 2005-94603 discloses a headphone device that can reduce discomfort caused by pop noise that accompanies power on / off during use, and has a simple structure. The headphone device is a headphone device capable of turning on and off the power supply, provided in at least one of a pair of headphone units incorporating a speaker unit, a headphone band connecting the headphone units, and the headphone unit, Provided with a power switch for controlling the state of power supply, the headphone unit is rotatable about the extension direction of the headphone band as a central axis, and the power switch is turned on / off according to the rotation position of the headphone unit Is.

  According to Japanese Patent Laid-Open No. 2005-218006, consumption is performed by stopping / restarting the operation of each circuit by operating means such as an audio mode, a video mode, and a normal mode that normally outputs audio and video according to user preference. An easy-to-use portable digital broadcast receiver is disclosed by suppressing power and providing various modes to simplify the mode switching operation. The portable digital broadcast receiving apparatus includes a digital reception demodulation unit that receives and demodulates a desired broadcast wave, a video decoding unit that reproduces a video signal from the output of the digital reception demodulation unit, and a video that displays the output of the video decoding unit A display device, an audio decoding unit that reproduces an audio signal from the output of the digital reception demodulation unit, an audio presentation device that outputs the output of the audio decoding unit, an operation unit that sets an output of a digital broadcast video, and The video decoding unit and a control unit that controls the operation of the video display device. When the control unit is selected to reproduce only audio by the operation unit, the video decoding unit and the video Control is performed so as to stop the operation of the display device.

  Japanese Patent Application Laid-Open No. 11-195931 discloses a noise removal circuit that can reliably suppress a nuisance generated when a power supply voltage is turned on / off with a simple circuit configuration. The noise elimination circuit is an on / off detection circuit that outputs an on / off detection signal only for a predetermined period when the power switch is turned on / off in a noise elimination circuit that suppresses a noise generated when the power switch is turned on / off. A buffer circuit that allows the impedance to be changed in at least two stages and allows an audio signal to pass with the set impedance, and the buffer circuit is otherwise configured while the on / off detection signal is being output. It is characterized in that the impedance is set to be larger than the period.

JP 2003-110441 A JP 2005-94603 A JP 2005-218006 A JP-A-11-195931

  The subject of this invention is providing the audio | voice output apparatus and noise prevention measure which prevent the noise which generate | occur | produces from the detachable earphone.

  The audio output device according to the present invention includes an earphone insertion detection unit and a power supply control unit. The earphone insertion detection unit uses a sensor to detect whether or not an earphone that converts an electrical signal generated by the earphone amplifier into sound has been removed. After detecting that the earphone has been removed, the power supply control unit turns off the power supply for supplying the earphone amplifier with power for generating the electrical signal.

  The noise prevention measure according to the present invention includes a step of detecting whether or not an earphone that converts an electric signal generated by an earphone amplifier into sound is removed using a sensor, and after detecting that the earphone has been removed. And a step of turning off a power source that supplies power for generating the power to the earphone amplifier.

  The noise prevention program according to the present invention is a computer program that causes a computer to realize an earphone insertion detection unit and a power supply control unit. The earphone insertion detection unit uses a sensor to detect whether or not an earphone that converts an electrical signal generated by the earphone amplifier into sound has been removed. After detecting that the earphone has been removed, the power control unit turns off the power to supply the earphone amplifier with power for generating the electrical signal.

  The sound output device and the noise prevention measure according to the present invention can prevent noise generated from the earphone when the power is turned off by turning off the power after the earphone is removed.

  Embodiments of an audio output device according to the present invention will be described with reference to the drawings. The audio output device is applied to a mobile phone terminal. As shown in FIG. 1, the cellular phone terminal 1 includes a control unit 2, a memory 3, an operation unit 5, a display unit 6, a radio unit 7, and an audio / audio signal processing unit 8. The control unit 2 includes a CPU 10 and executes a computer program installed in the mobile phone terminal 1 to control the memory 3, the operation unit 5, the display unit 6, the radio unit 7, and the audio / audio signal processing unit 8. . The memory 3 records the computer program and temporarily records information generated by the control unit 2. The memory 3 further records audio data. The operation unit 5 includes a plurality of keys, generates information when operated by a user, and outputs the information to the control unit 4. The display unit 6 displays a screen generated by the control unit 4.

  The radio unit 7 includes an antenna 11, receives a radio signal from an external device using the antenna 11, demodulates the radio signal into reception information, and outputs the received information to the control unit 4. The radio unit 7 further modulates the transmission information generated by the control unit 4 into a radio signal, and transmits the radio signal to an external device using the antenna 11. As the external device, a base station applied to a mobile phone communication network is exemplified.

  The audio / audio signal processing unit 8 includes an output device 12 and a microphone 14. The voice / audio signal processing unit 8 generates voice information indicating the voice collected by the microphone 14 and outputs the voice information to the control unit 4. The audio / audio signal processing unit 8 is further controlled by the control unit 4 to output audio using the output device 12.

  FIG. 2 shows the voice / audio signal processing unit 8. The audio / audio signal processing unit 8 includes a power source 20, a sound source 21, a D / A (digital / analog) converter 22, a receiver amplifier 23, a speaker amplifier 24, an earphone amplifier 25, a mute circuit 29, and a sensor 30. . At this time, the output device 12 includes a receiver 26, a speaker 27, and an earphone 28.

  The power source 20 is controlled by the control unit 4 to be turned on or turned off. The power source 20 supplies power to the receiver amplifier 23, the speaker amplifier 24, and the earphone amplifier 25 when turned on. When the power supply 20 is turned off, the power supply 20 stops supplying power to the receiver amplifier 23, the speaker amplifier 24, and the earphone amplifier 25. The power supply 20 further has a plurality of modes, and is switched to one of the plurality of modes by the control unit 2. The plurality of modes includes a normal mode and a power saving mode. The power supply 20 supplies power to the receiver amplifier 23, the speaker amplifier 24, and the earphone amplifier 25 so that the receiver amplifier 23, the speaker amplifier 24, and the earphone amplifier 25 operate normally when switched to the normal mode. To do. When the power supply 20 is switched to the power saving mode, the power supply 20 reduces the power supplied to the receiver amplifier 23, the speaker amplifier 24, and the earphone amplifier 25 without a sharp voltage drop. At this time, the power source 20 has a smaller current consumed in the power saving mode than the current consumed in the normal mode, for example, about several μA.

  The sound source 21 generates a digital signal indicating sound. For example, the sound source 21 is a block for music reproduction. At this time, the sound data is read from the memory 3 and the sound data is output as a digital signal. The sound source 21 can also be configured by a tone generation circuit or the like. The sound source 21 is configured as an independent block outside the control unit 2 in the present embodiment, but may be incorporated in the control unit 2 as a playback module.

  The D / A converter 22 converts the digital signal generated by the sound source 21 into an analog signal. The receiver amplifier 23 amplifies the analog signal converted by the D / A converter 22 using the power supplied from the power supply 20 to generate an electrical signal, and outputs the electrical signal to the receiver 26. The receiver 26 converts the electrical signal output from the receiver amplifier 23 into sound and outputs the sound. The speaker amplifier 24 amplifies the analog signal converted by the D / A converter 22 using the power supplied from the power supply 20 to generate an electrical signal, and outputs the electrical signal to the speaker 27. The speaker 27 converts the electrical signal output from the speaker amplifier 24 into sound and outputs the sound.

  The earphone amplifier 25 amplifies the analog signal converted by the D / A converter 22 using the electric power supplied from the power supply 20 to generate an electric signal, and outputs the electric signal to the earphone 28. The earphone 28 can be attached to and detached from the mobile phone terminal 1 by a user operation. The earphone 28 converts the electrical signal output from the earphone amplifier 25 into sound and outputs it when inserted in the mobile phone terminal 1. The sensor 30 detects whether the earphone 28 is inserted into or removed from the mobile phone terminal 1, and outputs the detection result to the control unit 2.

  The mute circuit 29 is formed of an FET (Field-Effect Transistor). The mute circuit 29 is controlled by the control unit 4 and does not ground the wiring for transmitting the electric signal output from the earphone amplifier 25 to the earphone 28 or grounds the wiring. That is, the mute circuit 29 is controlled by the control unit 4 and cancels mute so that sound is output from the earphone 28 or mute so that sound is not output from the earphone 28. When the power supply 20 is turned off, the mute circuit 29 generates a steep voltage drop in the wiring and generates a popping sound from the earphone 28.

  FIG. 3 shows a computer program installed in the mobile phone terminal 1. The computer program includes a mobile phone unit 31, an earphone insertion detection unit 32, a ringing event detection unit 33, a ringing control unit 34, an amplifier control unit 35, and a power supply control unit 36.

  The mobile phone unit 31 causes the mobile phone terminal 1 to function as a mobile phone. That is, in response to a predetermined operation input to the operation unit 5, the mobile phone unit 31 uses the wireless unit 7 to transmit the sound collected by the microphone 14 to another computer via the mobile phone communication network. The audio transmitted and received from the computer via the mobile phone communication network is output from the output device 12. In response to a predetermined operation input to the operation unit 5, the mobile phone unit 31 further transmits an email created via the operation unit 5 to another computer using the wireless unit 7, and The electronic mail received from the computer is displayed on the display unit 6. The mobile phone communication network can be replaced with another communication line network. Examples of the communication line network include a LAN (Local Area Network), the Internet, and a dedicated line.

  The earphone insertion detection unit 32 uses the sensor 30 to detect whether the earphone 28 is inserted into or removed from the mobile phone terminal 1.

  The ringing event detection unit 33 detects a ringing event or a ringing off event. The ringing event indicates an event for generating sound from the output device 12. The ringing event is exemplified by pressing a key of the operation unit 5. The ringing off event is an event for stopping the sound generated from the output device 12. An example of the ringing off event is that a predetermined time has elapsed since the beginning of the sound.

  The ringing controller 34 controls the mute circuit 29 to mute so that no sound is output from the earphone 28 at a predetermined timing, or controls the mute circuit 29 so that sound is output from the earphone 28. To release.

  The amplifier control unit 35 activates the earphone amplifier 25 or stops the earphone amplifier 25 at a predetermined timing.

  The power supply control unit 36 turns on the power supply 20 or turns off the power supply 20 at a predetermined timing. Furthermore, the power supply control unit 36 sets the mode of the power supply 20 to the normal mode or sets the mode of the power supply 20 to the power saving mode at a predetermined timing.

  The embodiment of the noise prevention measure according to the present invention is executed by the cellular phone terminal 1 and operates as a cellular phone, when a ringing event is detected, and when an earphone 28 is inserted or removed. And.

  In the operation as the cellular phone, the cellular phone terminal 1 responds to pressing of a predetermined key on the operation unit 5 and uses the radio unit 7 to transmit the voice collected by the microphone 14 to another computer. The output device 12 outputs the voice transmitted through the communication network and received from the computer through the mobile phone communication network. In response to pressing of a predetermined key on the operation unit 5, the mobile phone terminal 1 further transmits an e-mail created via the operation unit 5 to another computer using the wireless unit 7. The e-mail received from is displayed on the display unit 6.

  The operation when an event related to the ringing is detected will be described below. When the earphone 28 is inserted and a ringing event is detected, the cellular phone terminal 1 mutes using the mute circuit 29, switches the mode of the power supply 20 to the normal mode, and activates the earphone amplifier 25. The mute circuit 29 is used to cancel mute. According to such an operation, the cellular phone terminal 1 outputs the sound generated by the sound source 21 from the earphone 28 after the mute is released.

When the earphone 28 is removed and the ringing event is detected, the mobile phone terminal 1 mutes using the mute circuit 29, turns on the power source 20, activates the earphone amplifier 25, and activates the mute circuit 29. Use to unmute. According to such an operation, the mobile phone terminal 1 outputs the sound generated by the sound source 21 from the receiver 26 and the speaker 27 after the mute is released.
When the earphone 28 is inserted and a ringing off event is detected, the mobile phone terminal 1 mutes using the mute circuit 29 and sets the power source 20 to the power saving mode. According to such an operation, the mobile phone terminal 1 is prevented from outputting the sound generated by the sound source 21 from the earphone 28 after being muted.

  The cellular phone terminal 1 turns off the power supply 20 when the earphone 28 is removed and a ringing off event is detected. According to such an operation, the mobile phone terminal 1 is prevented from outputting the sound generated by the sound source 21 from the receiver 26 and the speaker 27 after being muted.

  FIG. 4 shows an operation when the insertion / removal of the earphone 28 is detected. When the mobile phone terminal 1 detects that the earphone 28 has been inserted by the sensor 30 or when it has been detected that the earphone 28 has been removed, it first generates an interrupt (step S1). When the cause of the interruption is the insertion or removal of the earphone 28 (step S2, YES), the cellular phone terminal 1 determines whether the earphone 28 has been inserted or the earphone 28 has been removed (step S3).

  The cellular phone terminal 1 determines whether or not it is ringing when the earphone 28 is inserted (step S3, with earphone) (step S4). When the mobile phone terminal 1 is not ringing (step S4, ringing OFF), the power source 20 is turned on (step S5), and the mode of the power source 20 is set to the power saving mode (step S6).

  When the earphone 28 is removed (step S3, no earphone), the cellular phone terminal 1 determines whether or not it is ringing (step S7). When the cellular phone terminal 1 is not ringing (step S7, ringing OFF), the power source 20 is turned off (step S8), and the mode of the power source 20 is set to the normal mode (step S9).

  Such an operation changes only the process related to the earphone 28 and does not affect the sounding process of the output device 12 (receiver 26 or speaker 27) other than the earphone 28.

  FIG. 5 shows states that can be taken by the mobile phone according to the comparative example of the present invention. The state includes state A to state D. The state A is a state in which no sound is generated and the earphone 28 is not inserted. The power supply 20 is turned off in the state A, and the mode is the normal mode. State B is a state in which the sound is being played and the earphone 28 is not inserted. The power supply 20 is turned on in the state B, and the mode is the normal mode. State C is a state in which the sound is being played and the earphone 28 is inserted. The power supply 20 is turned on in the state C, and the mode is the normal mode. The state D is a state in which the sound is not ringing and the earphone 28 is inserted. The power supply 20 is turned off in the state D, and the mode is the normal mode.

  When a ringing event is detected in the state A, the mobile phone terminal of the comparative example is turned on and makes a transition to the state B. When the ringing off event is detected in the state B, the power source 20 is turned off and the mobile phone terminal of the comparative example transits to the state A. The mobile phone terminal of the comparative example transitions to the state C when the earphone 28 is inserted in the state B. The mobile phone terminal of the comparative example transitions to the state B when the earphone 28 is pulled out in the state C. The mobile phone terminal of the comparative example transitions to the state D when the earphone 28 is inserted in the state A. The mobile phone terminal of the comparative example transitions to the state A when the earphone 28 is pulled out in the state D. In the mobile phone terminal of the comparative example, when a ringing event is detected in the state D, the power source 20 is turned on and the state transitions to the state C. When the ringing off event is detected in the state C, the power source 20 is turned off and the mobile phone terminal of the comparative example transits to the state D. At this time, a steep voltage drop occurs in the wiring connected to the earphone 28 by the mute circuit 29, and noise is generated from the earphone 28.

  FIG. 6 shows the control timing in the mobile phone terminal of the comparative example. The mobile phone terminal of the comparative example is not ringing, and in the state A where the earphone 28 is not inserted, when the earphone 28 is inserted, the power supply 20 is not turned on but remains off. When a ringing event is detected, the cellular phone terminal of the comparative example mutes using the mute circuit 29, turns on the power source 20, activates the earphone amplifier 25, and releases the mute using the mute circuit 29. When the mute is released, the mobile phone terminal of the comparative example outputs sound from the earphone 28 and is ringing.

  When a ringing off event is detected while ringing, the mobile phone terminal of the comparative example mutes using the mute circuit 29 and stops the earphone amplifier 25. When the cellular phone terminal of the comparative example is muted, it stops outputting sound from the earphone 28. According to such mute, it is possible to prevent noise that occurs when the earphone amplifier 25 is turned on or a path is switched when a button confirmation sound is sounded. The mobile phone terminal of the comparative example turns off the power supply 20 after a few seconds (for example, 10 seconds) have elapsed since the ringing off event was detected. In the mobile phone terminal of the comparative example, when the power supply 20 is turned off before the earphone 28 is removed, a steep voltage drop occurs in the wiring connected to the earphone 28 by the mute circuit 29, and noise is generated from the earphone 28.

  When music data is played continuously, the above noise is inconspicuous because the ringing end process is not performed during ringing. In particular, the button confirmation sound that rings when a button is operated starts to ring each time the button is pressed. Since the processing and ringing end processing are performed, the occurrence of noise is easily understood by the user.

  In order to prevent the above-mentioned noise, it is conceivable to keep the power supply 20 on even while the earphone 28 does not ring. In this case, useless current is consumed, and the battery is consumed quickly. Further, by using a timer after the ringing ends and turning off the power supply 20 after a few seconds (for example, 10 seconds), it is difficult for the user to understand the occurrence of noise. At this time, after a few seconds, noise occurs and is not a permanent measure. In addition, when the timer is used, if the earphone is pulled out before the timer ends, the power of the amplifier remains on, and wasteful current is consumed.

  FIG. 7 shows states that the cellular phone 1 according to the present invention can take. The states include states A to D as in the mobile phone terminal of the comparative example described above. The state A is a state in which no sound is generated and the earphone 28 is not inserted. The power supply 20 is turned off in the state A, and the mode is the normal mode. State B is a state in which the sound is being played and the earphone 28 is not inserted. The power supply 20 is turned on in the state B, and the mode is the normal mode. State C is a state in which the sound is being played and the earphone 28 is inserted. The power supply 20 is turned on in the state C, and the mode is the normal mode. The state D is a state in which the sound is not ringing and the earphone 28 is inserted. The power supply 20 is turned on in the state D, and the mode is the power saving mode.

  When a ringing event is detected in the state A, the mobile phone terminal 1 is turned on and makes a transition to the state B. When the ringing off event is detected in the state B, the cellular phone terminal 1 is turned off and the state is changed to the state A. The mobile phone terminal 1 transitions to the state C when the earphone 28 is inserted in the state B. The mobile phone terminal 1 transitions to the state B when the earphone 28 is pulled out in the state C. When the earphone 28 is inserted in the state A, the cellular phone terminal 1 is turned on, the mode of the power source 20 is set to the power saving mode, and the state transitions to the state D. When the earphone 28 is pulled out in the state D, the cellular phone terminal 1 is set to the power saving mode, the power source 20 is turned on, and the state transitions to the state A. When a ringing event is detected in the state D, the cellular phone terminal 1 is set to the normal mode in the power source 20 and transitions to the state C. When the ringing off event is detected in the state C, the mobile phone terminal 1 is set to the power saving mode and transitions to the state D. At this time, the mute circuit 29 does not cause a steep voltage drop in the wiring connected to the earphone 28, and no noise is generated from the earphone 28.

  Such state transition changes only the processing related to the earphone (transition between state A and state D, transition between state C and state D), and the output device 12 other than the earphone 28 (receiver 26 and speaker 27). The ringing process (transition between state A and state B, transition between state B and state C) is not affected. That is, the cellular phone terminal 1 sets the mode of the power source 20 to the normal mode at the same time as the power source 20 is turned off when the earphone 28 is pulled out, so that the processing of the receiver 26 and the speaker 27 other than the earphone 28 has been conventionally performed. This is preferable because it is not necessary to change this.

  According to such a transition, the mobile phone terminal 1 is not ringing and the power supply 20 is in the power saving mode in the state D in which the earphone 28 is inserted, and wasteful current is consumed. It is possible to prevent battery consumption from being accelerated.

  FIG. 8 shows the control timing in the mobile phone terminal 1. When the earphone 28 is inserted in the state where the mobile phone terminal 1 is not ringing and the earphone 28 is not inserted, the power supply 20 is turned on and the mode of the power supply 20 is set to the power saving mode. . When a ringing event is detected, the cellular phone terminal 1 mutes using the mute circuit 29, sets the mode of the power source 20 to the normal mode, activates the earphone amplifier 25, and releases the mute using the mute circuit 29. . When the mute is released, the mobile phone terminal 1 outputs sound from the earphone 28 and is ringing.

  When the ringing off event is detected while ringing, the cellular phone terminal 1 mutes using the mute circuit 29 and stops the earphone amplifier 25. When the mobile phone terminal 1 is muted, it stops outputting sound from the earphone 28. The cellular phone terminal 1 sets the mode of the power source 20 to the power saving mode after being muted. The cellular phone terminal 1 turns off the power supply 20 after the earphone 28 is removed. When the power supply 20 is turned off after the earphone 28 is removed in this manner, the mobile phone terminal 1 does not generate a steep voltage drop in the wiring connected to the earphone 28 by the mute circuit 29, and no noise is generated from the earphone 28.

  In another embodiment of the noise prevention measure according to the present invention, the noise prevention measure in the above-described embodiment is replaced with another process.

  FIG. 9 shows a state that the mobile phone 1 that executes such a noise prevention measure can take. The states include states A to D as in the mobile phone terminal of the comparative example described above. The state A is a state in which no sound is generated and the earphone 28 is not inserted. The power supply 20 is turned off in the state A, and the mode is the normal mode. State B is a state in which the sound is being played and the earphone 28 is not inserted. The power supply 20 is turned off in the state B, and the mode is the normal mode. State C is a state in which the sound is being played and the earphone 28 is inserted. The power supply 20 is turned on in the state C, and the mode is the normal mode. The state D is a state in which the sound is not ringing and the earphone 28 is inserted. The power supply 20 is turned on in the state D, and the mode is the power saving mode.

  When the ringing event is detected in the state A, the mobile phone terminal 1 transits to the state B. When the ringing off event is detected in the state B, the mobile phone terminal 1 transitions to the state A. When the earphone 28 is inserted in the state B, the mobile phone terminal 1 is turned on and changes to the state C. When the earphone 28 is pulled out in the state C, the mobile phone terminal 1 is turned off and the state transitions to the state B. When the earphone 28 is inserted in the state A, the cellular phone terminal 1 is turned on, the mode of the power source 20 is set to the power saving mode, and the state transitions to the state D. When the earphone 28 is pulled out in the state D, the cellular phone terminal 1 is set to the power saving mode, the power source 20 is turned on, and the state transitions to the state A. When a ringing event is detected in the state D, the cellular phone terminal 1 is set to the normal mode in the power source 20 and transitions to the state C. When the ringing off event is detected in the state C, the mobile phone terminal 1 is set to the power saving mode and transitions to the state D. At this time, the mobile phone terminal 1 does not output sound from the output device 12 in the state B, but a steep voltage is applied to the wiring connected to the earphone 28 by the mute circuit 29 in the same manner as the noise prevention measure in the above-described embodiment. No descent occurs and no noise is generated from the earphone 28.

  When the button confirmation sound is sounded in a state where the earphone 28 is not inserted, the state A is changed to the state B, but the power source 20 is not turned on when the receiver 26 or the speaker 27 is sounded. Therefore, even when the ringing from state B to state A is completed, the power supply 20 is not turned off. Conversely, when the state B changes to the state C (for example, the earphone 28 is inserted while the button confirmation sound is sounding), the power source 20 needs to be turned on at this timing. Further, when the earphone 28 is pulled out while the earphone 28 in the state C is ringing, the amplifier power source 20 is turned off at the timing of transition from the state C to the state B.

  According to such a transition, the mobile phone terminal 1 is not ringing and the power supply 20 is in the power saving mode in the state D in which the earphone 28 is inserted, and wasteful current is consumed. It is possible to prevent battery consumption from being accelerated.

  Note that the mobile phone terminal 1 can also apply a power source without a power saving mode as the power source 20. At this time, the mobile phone terminal 1 consumes a wasteful current and accelerates battery consumption, but noise generated from the earphone 28 can be prevented.

FIG. 1 is a block diagram showing an embodiment of an audio output device according to the present invention. FIG. 2 is a block diagram showing the voice / audio signal processing unit. FIG. 3 is a block diagram showing a computer program installed in the audio output device according to the present invention. FIG. 4 is a flowchart showing an operation when an earphone is inserted or removed. FIG. 5 is a state transition diagram in a comparative example of a noise prevention measure according to the present invention. FIG. 6 is a timing chart in the comparative example of the noise prevention measure according to the present invention. FIG. 7 is a state transition diagram in the noise prevention measure according to the present invention. FIG. 8 is a timing chart in the noise prevention measure according to the present invention. FIG. 9 is a state transition diagram in another embodiment of the noise prevention measure according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Cellular phone terminal 2: Control part 3: Memory 4: Control part 5: Operation part 6: Display part 7: Radio | wireless part 8: Audio | voice / audio signal processing part 11: Antenna 12: Output device 14: Microphone 20: Power supply 21 : Sound source 22: D / A converter 23: Receiver amplifier 24: Speaker amplifier 25: Earphone amplifier 26: Receiver 27: Speaker 28: Earphone 30: Sensor 31: Mobile phone unit 32: Earphone insertion detection unit 33: Ring event detection unit 34: Ringing control unit 35: Amplifier control unit 36: Power supply control unit

Claims (15)

An earphone insertion detection unit that detects whether or not an earphone that converts an electrical signal generated by the earphone amplifier into sound is removed using a sensor;
An audio output device comprising: a power supply control unit that turns off a power supply that supplies power for generating the electrical signal to the earphone amplifier after detecting that the earphone is removed. In claim 1,
A ring event detection unit for detecting a ring event or a ring off event;
The power supply control unit controls the power supply so that the power is reduced after the earphone is inserted and the ringing off event is detected. In claim 2,
The power supply control unit controls the power supply so that the power is supplied to the earphone amplifier after the earphone is disconnected or the ringing event is detected. In either claim 2 or claim 3,
The power control unit turns off the power after the earphone is unplugged and the ringing off event is detected, and turns on the power after the earphone is unplugged and the ringing event is detected. Sound output device. In either claim 2 or claim 3,
The power control unit turns off the power after the ringing event is detected and the earphone is removed, and turns on the power after the ringing event is detected and the earphone is inserted. Sound output device. Detecting whether an earphone for converting an electrical signal generated by the earphone amplifier into sound is removed using a sensor;
A noise prevention measure comprising: turning off a power source that supplies power for generating the electrical signal to the earphone amplifier after detecting that the earphone has been removed. In claim 6,
Detecting a ringing event or ringing off event;
And a step of controlling the power supply so that the power is reduced after the earphone is inserted and the ring-off event is detected. In claim 7,
The noise prevention measure further comprising the step of controlling the power supply so that the power is supplied to the earphone amplifier after the earphone is unplugged or the ringing event is detected. In either claim 7 or claim 8,
Turning off the power after the earphone is unplugged and the ring off event is detected;
A noise prevention measure further comprising: turning on the power after the earphone is unplugged and the ringing event is detected. In either claim 7 or claim 8,
Turning off the power after the ringing event is detected and the earphone is removed;
A noise prevention measure further comprising: turning on the power after the ringing event is detected and the earphone is inserted. An earphone detection means for detecting whether an earphone for converting an electrical signal generated by the earphone amplifier into sound using a sensor is removed;
A noise prevention program for causing a computer to realize power supply control means for turning off a power supply for supplying power for generating the electric signal to the earphone amplifier after detecting that the earphone is removed. In claim 11,
A program for causing a computer to implement a ringing event detection means for detecting a ringing event or a ringing off event;
The noise prevention program for controlling the power supply so that the power is reduced after the earphone is inserted and the ringing off event is detected. In claim 12,
The noise prevention program for controlling the power supply so that the power is supplied to the earphone amplifier after the earphone is pulled out or the ringing event is detected. Either of claim 12 or claim 13,
The power control means turns off the power after the earphone is unplugged and the ringing off event is detected, and turns on the power after the earphone is unplugged and the ringing event is detected. Yes Noise prevention program. Either of claim 12 or claim 13,
The power control means turns off the power after the ringing event is detected and the earphone is removed, and turns on the power after the ringing event is detected and the earphone is inserted. Yes Noise prevention program.

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