JP2018125798A - Portable audio player - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a portable voice reproducer capable of suppressing pop noise.SOLUTION: A portable voice reproducer generates an analog audio-signal based on digital voice data, and reproduces voice via a voice output device. The portable voice reproducer includes a voice electrode electrically connected with the connection terminal of the voice output device, a voice signal generation circuit for generating a voice signal based on the voice data and outputting to the voice electrode, a control circuit for outputting the voice data to the voice signal generation circuit, and a voice switch for interconnecting the output terminals of the voice electrode and the voice signal generation circuit, or connecting with a ground terminal, in response to a control signal from the control circuit.SELECTED DRAWING: Figure 7

Description

  The present invention relates to a portable audio player.

  There is known a portable audio player that generates an analog audio signal based on digital audio data and reproduces the audio via an audio output device such as an earphone or a headphone. Such a portable audio player generates, for example, an audio electrode electrically connected to a connection terminal (for example, an earphone jack) of an audio output device, and the audio signal based on the audio data. An audio signal generation circuit for outputting, and a control circuit for outputting audio data to the audio signal generation circuit.

JP 2007-011088 A

  For example, when an earphone jack or the like is inserted in a state where the power is supplied to the portable audio player, the charge of the audio electrode is released upon contact with the earphone jack or the like, which may cause pop noise.

  Further, for example, the audio signal itself may include pop noise. For example, when two audio data having different sampling frequencies are continuously reproduced by a portable audio player, pop noise may occur when the audio data is switched.

  The present invention has been made in view of such problems, and an object thereof is to provide a portable audio player capable of suppressing pop noise.

  A portable audio player according to an embodiment of the present invention is a portable audio player that generates an analog audio signal based on digital audio data and reproduces audio via an audio output device. This portable audio player includes an audio electrode that is electrically connected to a connection terminal of an audio output device, an audio signal generation circuit that generates an audio signal based on audio data, and outputs the audio signal to the audio electrode, and the audio signal A control circuit that outputs audio data to the generation circuit, and an audio switch that connects the output terminals of the audio electrode and the audio signal generation circuit to each other or to the ground terminal in accordance with a control signal from the control circuit; Is provided.

  For example, the voice switch includes a first switch circuit that connects a voice electrode to a first node or a second node according to a control signal, and a third output terminal of the voice signal generation circuit according to the control signal. And a second switch circuit connected to the node or the fourth node. In addition, at least one of the first and third nodes is provided on an audio signal transmission path from the audio electrode to the output terminal of the audio signal generation circuit, and the second and fourth nodes are connected to the ground terminal. Also good. The voice switch may further include a resistor and a capacitor connected in parallel between the second and fourth nodes and the ground terminal.

  For example, in the portable audio player, when the portable audio player is turned on, the audio electrode and the output terminal of the audio signal generating circuit are connected to the ground terminal, and the audio electrode and the audio signal generating circuit are used for reproducing the audio. Output terminals may be connected to each other.

  Also, for example, in the portable audio player, when the audio is sequentially reproduced based on the first and second audio data, and the sampling frequencies of the first and second audio data are different, When the reproduction of the sound based on the first sound data is finished, the sound electrode and the output terminal of the sound signal generation circuit are connected to the ground terminal, and when the sound reproduction based on the second sound data is started, the sound electrode and The output terminals of the audio signal generation circuit may be connected to each other. In this case, for example, when the sampling frequencies of the first and second audio data are the same, the first and second audio electrodes and the output terminals of the audio signal generation circuit are connected to each other. The voice data may be switched.

  Further, for example, the control circuit may include fifth and sixth nodes, and may be operable by power supplied to any of the fifth and sixth nodes. The portable audio player includes a power supply circuit that generates a voltage of a predetermined magnitude and supplies the voltage to the fifth node, a battery that supplies power to the power supply circuit, and electrically connects the power supply circuit and the battery. A power switch to be connected or disconnected, and a voltage dividing circuit having an input terminal connected to the battery and an output terminal connected to the sixth node may be further provided.

  For example, when the power is turned off by the power switch, the control circuit may store the preliminary information by the power supplied from the sixth node before stopping the operation. This preliminary information may be, for example, the voltage of the sixth node.

  For example, the power switch may be a mechanical switch. Furthermore, the portable audio player may further include a power operation unit that can be operated from the outside of the housing, and this power operation unit may be mechanically linked with the power switch.

  According to the present invention, it is possible to provide a portable audio player capable of suppressing pop noise.

1 is a front view showing an external appearance of a portable audio player according to a first embodiment of the present invention. It is a bottom view which shows the external appearance of the portable audio player. It is a top view which shows the external appearance of the portable audio | voice reproduction machine. It is a right view which shows the external appearance of the portable audio player. It is a left view which shows the external appearance of the portable audio player. It is a schematic functional block diagram which shows the internal structure of the portable audio player based on the embodiment. It is a schematic circuit diagram for demonstrating the circuit structure of a voice switch. It is a schematic circuit diagram for demonstrating the circuit structure of a monitor circuit. It is a flowchart for demonstrating operation | movement of the portable audio | voice reproduction machine. It is a flowchart for demonstrating one part operation | movement of the portable audio | voice reproduction machine.

[First Embodiment]
[Appearance of portable audio player]
1 to 5 are a front view, a bottom view, a plan view, a right side view, and a left side view, respectively, showing the external appearance of the portable audio player according to the first embodiment of the present invention. Note that the appearance of the portable audio player, the position, size and range of each component, specific aspects of each component, and the like can be changed as appropriate.

  As shown in FIG. 1, three buttons 102 are provided at the lower front of the housing 101, and a display 103 is provided above the buttons. The button 102 is used for operations such as sound reproduction, stop, music feed, and volume adjustment. The display 103 displays information related to the sound being played back and the selected sound.

  As shown in FIG. 2, an audio terminal 104, a charging terminal 105, and a light source 106 are provided at the lower part of the housing 101. A connection terminal (for example, an earphone jack) of an audio output device such as an earphone or a headphone can be connected to the audio terminal 104. The audio output device outputs audio in response to an audio signal input to the connection terminal. The portable audio player according to the present embodiment reproduces audio by outputting an audio signal to the audio output device. The charging terminal 105 is, for example, a terminal for a micro USB cable, and is used for charging a built-in battery, installing firmware, or the like. The light source 106 is, for example, a light source such as a light emitting diode, and emits light according to the state of the built-in battery, the state of charge, or the like.

  As shown in FIG. 3, a recording medium insertion unit 107 is provided on the top of the housing 101. The recording medium insertion unit 107 is a socket into which a semiconductor memory such as a microSD card or an SD card can be inserted. The portable audio player according to the present embodiment generates an audio signal based on the audio data recorded in the semiconductor memory.

  As shown in FIG. 4, a power operation unit 108 is provided on the right side surface of the housing 101. The power operation unit 108 is, for example, a slide-type switch, and is used to turn on and off the portable audio player. In addition, an accessory attachment portion to which accessories such as a strap can be attached is provided above the power supply operation unit 108. The accessory mounting portion includes a pin member 110 and the like, and a hole portion 111 is provided between the pin member 110 and the housing 101.

  As shown in FIG. 5, a button operation switching unit 109 is provided on the left side surface of the housing 101. The button operation switching unit 109 is used for switching the operation of the button 102, for example. For example, the operation of the button 102 may be locked by the operation of the button operation switching unit 109, or a different operation may be assigned to the button 102. For example, when the button operation switching unit 109 is in the first state, the first operation such as playback and music feed is assigned to the three buttons 102 on the front surface of the housing 101, respectively, and in the second state. The second operation such as display switching and volume adjustment may be assigned.

[Internal configuration of portable audio player]
FIG. 6 is a schematic functional block diagram showing the internal configuration of the portable audio player according to the first embodiment. In FIG. 6, a part of the configuration is omitted for convenience of explanation.

  The housing 101 stores an audio terminal 104, an audio signal generation circuit 201, a control circuit 202, an audio switch 203, a power circuit 204, a battery 205, a power switch 206, a charging circuit 207, a monitor circuit 208, and the like.

  The audio terminal 104 is, for example, a tripolar audio terminal including an audio electrode 141 for the left ear, an audio electrode 142 for the right ear, and electrodes 143 and 144 for grounding. The audio electrodes 141 and 142 and the grounding electrodes 143 and 144 mechanically hold a connection terminal (for example, an earphone jack) of the audio output device and are electrically connected to the connection terminal. The audio terminal 104 may have other configurations such as a two-pole type or a four-pole type.

  The audio signal generation circuit 201 is, for example, a DA converter, generates an analog audio signal based on digital audio data, and outputs the analog audio signal to the audio electrodes 141 and 142. Specifically, analog audio signals (L, R) for the left ear and the right ear are generated, and the audio terminal 104 is output from the output terminals 201L and 201R via the coupling capacitor CC and the audio switch 203, respectively. To the voice electrodes 141 and 142. The audio data referred to here is, for example, music data of high resolution audio (hereinafter referred to as “high resolution”). The high-resolution music data includes, for example, both the sampling frequency and the number of quantization bits larger than the CD sound source, or one of the sampling frequency and the number of quantization bits larger than the CD sound source, and the other is a CD sound source. It is equivalent. The sampling frequency of the CD sound source is 44.1 kHz, and the number of quantization bits is 16 bits. The high-resolution music data has a data format such as FLAC (Free Lossless Audio Codec) or WAV. The audio signal referred to here is an analog AC signal and is output to an audio output device such as an earphone or a headphone to reproduce audio such as music.

  The control circuit 202 is, for example, an MCU, and operates according to the operation of the button 102 and the button operation switching unit 109 and the firmware stored in the ROM inside the control circuit 202. For example, when reproducing audio, the control circuit 202 reads audio data from the semiconductor memory 300 inserted into the recording medium insertion unit 107 and outputs the audio data to the audio signal generation circuit 201. The control circuit 202 controls the display 103 to display characters, numbers, logos, and the like. In addition, the control circuit 202 includes nodes N5 and N6, and can be operated by power supplied to any one of these nodes N5 and N6. In the present embodiment, the node N6 basically operates in accordance with the power supplied to the node N5, and the node N6 is used for a power monitor of the battery 205 or the like.

  The audio switch 203 is provided on an audio signal transmission path from the audio electrodes 141 and 142 to the output terminals 201L and 201R of the audio signal generation circuit 201. The sound switch 203 connects the sound electrodes 141 and 142 and the output terminals 201L and 201R of the sound signal generation circuit 201 to each other or grounds according to a sound output start / stop command (control signal) from the control circuit 202. Connect to the terminal. The voice switch 203 will be described in detail later with reference to FIG.

  The power supply circuit 204 is an integrated circuit such as a step-down circuit, a DC / DC converter, or a regulator, for example, and generates a voltage suitable for the operation of the audio signal generation circuit 201, the control circuit 202, the audio switch 203, the display 103, etc. Supply to these configurations.

  The battery 205 is a rechargeable battery such as a lithium ion battery, and supplies power to the power supply circuit 204. The battery 205 may be a replaceable battery.

  The power switch 206 is, for example, a mechanical switch that mechanically interlocks with the power operation unit 108, and electrically connects the node n10 connected to the power circuit 204 and the node n11 connected to the anode of the battery 205. Or cut. That is, in this embodiment, power is not supplied to the power supply circuit 204 when the power is turned off. The power switch 206 may not be a mechanical switch.

  The charging circuit 207 is an integrated circuit that adjusts the power supplied to the charging terminal 105 and supplies it to the battery 205, for example. In addition, the light source 106 is connected to the charging circuit 207, and the light source 106 is caused to emit light according to, for example, the state of the battery 205 or the state of charging.

  The monitor circuit 208 is used for monitoring the power of the battery 205 or the like. The monitor circuit 208 will be described later in detail with reference to FIG.

[Voice Switch 203 According to First Embodiment]
FIG. 7 is a schematic circuit diagram for explaining the circuit configuration of the voice switch 203. Although FIG. 7 illustrates a state in which voice output is permitted, the state of the voice switch 203 is switched by inputting a voice output start / stop command. The audio switch 203 includes a left ear circuit 203L and a right ear circuit 203R. In the following description, the left ear circuit 203L will be described as an example, but the right ear circuit 203R is configured in the same manner as the left ear circuit 203L. Furthermore, the configuration of the voice switch 203 can be changed as appropriate. For example, part or all of the voice switch 203 can be realized by an FPGA (Field Programmable Gate Array) or the like.

  The audio switch 203L includes a first switch circuit 231 connected to the audio electrode 141, a second switch circuit 232 connected to the output terminal 201L of the audio signal generation circuit 201 via a coupling capacitor CC, and the second A ground circuit 233 connected to the first switch circuit 231 and the second switch circuit 232;

  The first switch circuit 231 is a switch circuit that connects the audio electrode 141 to the first node N1 in response to the audio output start command and connects to the second node N2 in response to the audio output stop command. The first node N1 is connected to the output terminal 201L of the audio signal generation circuit 201 via the coupling capacitor CC. The second node N2 is connected to the ground terminal via the resistor R231 and the ground circuit 233. The first switch circuit may be, for example, a circuit that amplifies a low-frequency signal, and may have a conduction resistance of 1Ω or less. Further, the coupling capacitor CC may be, for example, a tantalum capacitor.

  The second switch circuit 232 connects the output terminal 201L of the audio signal generation circuit 201 to the third node N3 according to the audio output start command, and connects to the fourth node N4 according to the audio output stop command. It is a switch circuit. The third node N3 is not connected anywhere. The fourth node N4 is connected to the ground terminal via the ground circuit 233.

  Note that the first and third nodes N1 and N3 may be provided on the transmission path of the audio signal, at least one of which is from the audio electrode 141 to the output terminal 201L of the audio signal generation circuit 201. For example, the third node N3 may be connected to the audio electrode 141, and in this case, the first node N1 need not be connected anywhere. Further, the first node N1 may be connected to the third node N3 instead of the output terminal 201L.

  The ground circuit 233 includes a resistor R232 and a capacitor C232 connected in parallel between the second and fourth nodes N2, N4 and the ground terminal. The ground circuit 233 temporarily accumulates the charge of the input terminal in the capacitor C232, and gradually releases the charge to the ground terminal via the resistor R232.

  In the state where the audio output is permitted, the audio electrode 141 is connected to the output terminal 201L via the coupling capacitor CC as illustrated in FIG. As a result, the audio signal can be transmitted to the audio electrode 141. Further, the second node N 2 and the fourth node N 4 are connected to the ground circuit 233. Accordingly, no charge is accumulated in the second node N2 and the fourth node N4, and these potentials become the ground potential.

  When a voice output stop command is input to the voice switch 203, the connection destination of the voice electrode 141 is switched from the first node N 1 to the second node N 2 in the first switch circuit 231, and the output is output in the second switch circuit 232. The connection destination of the terminal 201L is switched from the third node N3 to the fourth node N4. Here, when charges are accumulated in the voice electrode 141 and the wiring connected thereto, the charges are gradually discharged through the resistor R231 and the ground circuit 233. Therefore, the pop noise accompanying switching hardly occurs.

  In a state where sound output is not permitted, the sound electrode 141 and the output terminal 201L are connected to the ground terminal via the ground circuit 233. Therefore, no charge is accumulated in the audio electrode 141 and the output terminal 201L, and these potentials become the ground potential.

  When a voice output start command is input to the voice switch 203, the connection destination of the voice electrode 141 is switched from the second node N2 to the first node N1 in the first switch circuit 231, as illustrated in FIG. In the second switch circuit 232, the connection destination of the output terminal 201L is switched from the fourth node N4 to the third node N3. Here, as described above, no charge is accumulated in the audio electrode 141 and the output terminal 201L, and these potentials are also the same potential. Therefore, the pop noise accompanying switching hardly occurs.

[Monitor Circuit 208 According to First Embodiment]
FIG. 8 is a schematic circuit diagram for explaining the circuit configuration of the monitor circuit 208. The monitor circuit 208 includes a voltage dividing circuit 281 and capacitors C281 and C282 connected in parallel between the output terminal and the ground terminal of the voltage dividing circuit 281. The voltage dividing circuit 281 steps down the voltage of the battery 205 so that the control circuit 202 can measure the voltage value of the battery 205. The voltage dividing circuit 281 has resistors R281 and R282, and has an input terminal connected to the anode of the battery 205 via the node n11 and an output terminal connected to the node N6 of the control circuit 202. The resistance ratio between the resistors R281 and R282 is determined so that, for example, the voltage value of the node N6 can be measured by the control circuit 202 when the battery 205 is charged to the maximum. Capacitor C281 stabilizes the current supplied to node N6. The capacitor C282 suppresses high frequency noise and has a smaller capacitance than the capacitor C281.

  When the switch 206 is in the ON state, power is supplied from the battery 205 to the power supply circuit 204, and power is supplied to the control circuit 202 via the node N5. The monitor circuit 208 steps down the voltage of the battery 205 so that the control circuit 202 can measure the voltage value of the battery 205.

  When the switch 206 is turned off, and thereby the power source of the portable audio player is turned off, the supply of power to the control circuit 202 via the node N5 is stopped. The control circuit 202 detects this and switches the power supply source from the node N5 to the node N6. Further, the control circuit 202 records the preliminary information with the power supplied from the node N6 before stopping the operation. The preliminary information referred to here is, for example, the voltage value of the node N6. After the operation of the control circuit 202 is stopped, the control circuit 202 does not operate until power is supplied to the node N5 again.

[Operation of portable audio player]
FIG. 9 is a flowchart for explaining the operation of the portable audio player according to the first embodiment. The following operations are executed by the CPU in the control circuit 202 according to the firmware stored in the ROM in the control circuit 202 (FIG. 6), for example, when the portable audio player is turned on.

  In step S100, a voice output stop command is output to the voice switch 203. That is, a voice output stop command is output when the portable audio player is turned on (immediately after the power is turned on). As a result, the output terminal 104 is electrically disconnected from the audio signal generation circuit 201, and the audio output is not permitted.

  In step S200, the state of the semiconductor memory 300 is detected. For example, whether or not the semiconductor memory 300 is inserted into the portable audio player, whether or not the semiconductor memory 300 can be handled, and audio data or data designating it are stored in the root directory of the semiconductor memory 300 It is determined whether or not it is done. Here, “data specifying it” is, for example, a playlist file, which specifies data such as the name of a subdirectory storing audio data, the name of audio data, and the playback order of audio data. is there. If all the conditions are satisfied, step S300 is started. If any of the conditions is not satisfied, a message to that effect is displayed on the display 103, and the process waits until all the conditions are satisfied. For example, it waits until the semiconductor memory 300 in which voice data or data designating it is stored in the root directory is inserted.

  In step S300, audio data is selected. For example, information related to audio data is displayed on the display 103 in such a manner that desired audio data can be selected. The information related to the audio data mentioned here includes, for example, a name (for example, a song name) corresponding to the audio data, a sampling frequency of the audio data, a name corresponding to the playlist, and the like. “Display in a selectable manner” means, for example, that a name corresponding to the audio data to be selected or a name corresponding to the playlist is displayed on the display 103 and is displayed on the display 103 according to the operation of the button 102. The audio data or playlist to be selected is switched, and thereby the user can select audio data or data designating the audio data. When the user determines audio data using the button 102 or the like, step S400 is started. For example, when selecting audio data, a sound effect may be generated according to the operation of the button 102. In this case, for example, a voice output start command may be output according to the operation of the button 102, a sound effect may be sounded, and a voice output stop command may be output.

  In step S300, for example, not only one piece of sound data but also sound data selected after that may be determined. For example, when the selected audio data is stored in the root directory of the semiconductor memory 300, the audio data stored in the root directory may be sequentially selected. For example, when the first audio data is designated by a playlist, the first audio data may be sequentially selected according to the playlist. Further, the audio data stored in the semiconductor memory 300 may be rearranged randomly and selected in the rearranged order.

  In step S400, a voice output start command is output to voice switch 203. That is, an audio output start command is output when reproducing audio. As a result, the output terminal 104 is electrically connected to the audio signal generation circuit 201, and the audio output is permitted. Here, “when playing back audio” means, for example, “from when audio data is selected until playback of audio based on this audio data is started”.

  In step S500, audio is reproduced. That is, the audio data selected in step S300 is read from the semiconductor memory 300 and output to the audio signal generation circuit 201. Also, the audio signal generation circuit 201 generates an audio signal based on this and outputs it to the audio electrodes 141 and 142. In addition, various monitoring is performed by the control circuit 202 during audio reproduction. For example, when other audio data or data designating it is selected, or when stop or music feed is performed, the operation is performed according to these operations. When the semiconductor memory 300 is pulled out, a message to that effect is displayed on the display 103 and the sound reproduction is interrupted. For example, step S600 is started when the reproduction of the sound is finished or when it is within a predetermined time immediately before the end.

  In step S600, the audio data is switched. This step will be described in detail with reference to FIG. When step S600 is completed, step S500 is started again.

  FIG. 10 is a flowchart for explaining step S600. The following operation is executed by the CPU inside the control circuit 202 according to the firmware stored in the ROM inside the control circuit 202 (FIG. 6), for example, with the start of step S600. In the following, the audio data before switching is referred to as first audio data, and the audio data after switching is referred to as second audio data.

  In step S601, it is determined whether the sampling frequency is changed. Specifically, it is determined whether the sampling frequency of the first audio data is the same as the sampling frequency of the second audio data. If the sampling frequencies are the same, step S602 is started. If changed, step S603 is started.

  In step S602, the audio data is switched. That is, the reproduction of the first audio data is finished and the reproduction of the second audio data is started. In step S602, the audio data is switched. However, the selection of the second audio data itself is performed before step S601, for example, in step S300 (FIG. 9).

  In step S603, a voice output stop command is output to the voice switch 203. That is, a sound output stop command is output when the reproduction of sound based on the first sound data is finished. As a result, the output terminal 104 is electrically disconnected from the audio signal generation circuit 201, and the audio output is not permitted. Here, “when the audio playback ends” may be, for example, “after the audio playback ends” or “within a predetermined time immediately before the audio playback ends”. May be.

  In step S604, the audio data is switched. Step S604 is performed in the same manner as step S602.

  In step S605, a voice output start command is output to the voice switch 203. In other words, a voice output start command is output when playback of voice based on the second voice data is started. As a result, the output terminal 104 is electrically connected to the audio signal generation circuit 201, and the audio output is permitted. Here, “when starting to play back the sound” may be, for example, “before starting to play back the sound based on the second sound data” or “based on the second sound data” It may be within a predetermined time immediately after the start of audio reproduction ”.

[Effect of portable audio player according to the first embodiment]
As described with reference to FIG. 7 and the like, the portable audio player according to the present embodiment generates an analog audio signal based on digital audio data and outputs the audio via an audio output device such as an earphone or a headphone. Is a portable audio player that reproduces. This portable audio player generates audio signals based on audio data 141 and 142 and audio electrodes 141 and 142 that are electrically connected to connection terminals (for example, earphone jacks) of the audio output device. The audio signal generation circuit 201 that outputs to the audio signal, the control circuit 202 that outputs audio data to the audio signal generation circuit 201, and the outputs of the audio electrodes 141 and 142 and the audio signal generation circuit 201 according to the control signal from the control circuit 202 The audio switch 203 connects the terminals 201L and 201R to each other or to a ground terminal.

  Here, for example, when an earphone jack or the like is inserted in a state where the power is applied to the portable audio player, the electric charges of the audio electrodes 141 and 142 are released upon contact with the earphone jack and the like, thereby generating pop noise. There was a case. However, in this embodiment, for example, prior to the insertion of an earphone jack or the like, the audio electrodes 141 and 142 can be connected to the ground terminal, and the charges of the audio electrodes 141 and 142 can be discharged in advance. . Thereby, pop noise can be suppressed.

  Further, for example, the audio signal itself may include pop noise. For example, when the audio data is high-resolution music data, the semiconductor memory 300 (FIG. 6) may store data of a plurality of types of sampling frequencies. Here, when two audio data flow continuously, if the sampling frequency of the audio data is different, pop noise may occur when the audio data is switched. However, in this embodiment, it is possible to suppress the occurrence of pop noise by separating the audio electrodes 141 and 142 from the output terminals 201L and 201R of the audio signal generation circuit 201 at the timing of switching between two audio data having different sampling frequencies. It is.

  For example, when the audio data is a live sound source or the like, the sampling frequency of the audio data that is continuously reproduced is often the same. Here, if the audio electrodes 141 and 142 are separated from the output terminals 201L and 201R of the audio signal generation circuit 201 up to such a case, the audio is interrupted at this timing. In order to prevent this, for example, when the sampling frequency of the audio data is not changed, the audio data 141 and 142 and the output terminals 201L and 201R of the audio signal generation circuit 201 are connected to each other. Can be switched.

  Further, as described with reference to FIG. 7 and the like, in the present embodiment, the audio electrodes 141 and 142 and the audio electrodes 141 and 142 and the audio electrodes 141 and 142 are separated from the output terminals 201L and 201R of the audio signal generation circuit 201. The output terminals 201L and 201R of the audio signal generation circuit 201 can be grounded. Therefore, since both the electric electrodes 141 and 142 and the output terminals 201L and 201R of the audio signal generation circuit 201 can be connected to each other, both charges can be discharged, and pop noise is also generated at this timing. Absent.

  The voice switch 233 according to the present embodiment includes a resistor R232 and a capacitor C232 connected in parallel between the second and fourth nodes N2 and N4 and the ground terminal.

  Here, when the audio electrodes 141 and 142 are connected to the ground terminal, the charge of the first node N1 is released to the second node N2, which may cause pop noise. However, in such a configuration, the charge of the first node N1 can be gradually released, and the pop noise at this timing can also be suppressed.

  In the portable audio player according to the present embodiment, as described with reference to FIG. 8 and the like, the control circuit 202 includes nodes N5 and N6 and is supplied to one of these nodes N5 and N6. It can be operated by electric power. Furthermore, the portable audio player according to the present embodiment includes a power supply circuit 204 that generates a voltage of a predetermined magnitude and supplies the voltage to the node N5, a battery 205 that supplies power to the power supply circuit 204, and these power supply circuits. The power switch 206 electrically connects or disconnects the battery 204 and the battery 205, and the voltage dividing circuit 281 having an input terminal connected to the battery 205 and an output terminal connected to the node N6.

  In such an aspect, for example, the control circuit 202 is operated by the power supplied to the node N5, and the node N6 can be used for monitoring the battery 205. In such an aspect, the power supply circuit 204 and the battery 205 are electrically disconnected in the OFF state, and the power supply is not monitored by firmware. Therefore, a configuration with less standby power can be realized. Further, for example, the control circuit 202 detects when the power is turned off by the power switch 206, switches the power supply source from the node N5 to the node N6, and is supplied from the node N6 before stopping the operation. Various operations can be performed by using the generated electric power. As such an operation, for example, recording of preliminary information such as the voltage of the node N6 can be considered.

  In the present embodiment, the power switch 206 is a mechanical switch. Therefore, almost no leakage current occurs in the power switch 206. Furthermore, the portable audio player according to the present embodiment further includes a power operation unit 108 that can be operated from the outside of the housing 101, and the power operation unit 108 is mechanically interlocked with the power switch 206.

[Other Embodiments]
The portable audio player according to the above embodiment is illustrated for explanation, and the specific configuration can be changed as appropriate.

  For example, FIG. 6 shows an example in which the audio signal generation circuit 201 and the control circuit 202 are realized by independent integrated circuits. However, for example, the audio signal generation circuit 201 and the control circuit 202 can be realized by a single integrated circuit.

  In addition, for example, the portable audio player according to the above embodiment does not include an audio output device, but the present invention can also be applied to those formed integrally with the audio output device.

  DESCRIPTION OF SYMBOLS 101 ... Case, 102 ... Button, 103 ... Display, 104 ... Audio | voice terminal, 105 ... Charging terminal, 106 ... Light source, 107 ... Recording medium insertion part, 108 ... Power supply operation part, 109 ... Button operation switching part, 110 ... Pin 201, audio signal generation circuit, 202 ... control circuit, 203 ... audio switch, 204 ... power circuit, 205 ... battery, 206 ... power switch, 207 ... charging circuit, 208 ... monitor circuit, 231 ... first switch circuit 232: a second switch circuit, 233: a ground circuit.

Claims (11)

A portable audio player that generates an analog audio signal based on digital audio data and reproduces the audio via an audio output device,
An audio electrode electrically connected to a connection terminal of the audio output device;
An audio signal generation circuit that generates the audio signal based on the audio data and outputs the audio signal to the audio electrode;
A control circuit for outputting the audio data to the audio signal generation circuit;
A portable audio player comprising: an audio switch that connects the audio electrode and the output terminal of the audio signal generation circuit to each other or to a ground terminal in accordance with a control signal from the control circuit. The voice switch is
A first switch circuit that connects the audio electrode to a first node or a second node in response to the control signal;
A second switch circuit for connecting an output terminal of the audio signal generation circuit to a third node or a fourth node according to the control signal,
At least one of the first and third nodes is provided on a transmission path of the audio signal from the audio electrode to an output terminal of the audio signal generation circuit;
The portable audio player according to claim 1, wherein the second and fourth nodes are connected to the ground terminal. The portable audio player according to claim 2, wherein the audio switch further includes a resistor and a capacitor connected in parallel between the second and fourth nodes and the ground terminal. Connecting the output terminal of the audio electrode and the audio signal generation circuit to the ground terminal when the portable audio player is powered on;
The portable audio player according to any one of claims 1 to 3, wherein the audio electrode and an output terminal of the audio signal generation circuit are connected to each other when reproducing the audio. When sequentially playing back sound based on the first and second sound data,
When the sampling frequencies of the first and second audio data are different,
Connecting the output terminal of the audio electrode and the audio signal generation circuit to the ground terminal when finishing the reproduction of the audio based on the first audio data;
The portable audio player according to any one of claims 1 to 4, wherein the audio electrode and an output terminal of the audio signal generation circuit are connected to each other when audio reproduction based on the second audio data is started. . When the sampling frequency of the first and second audio data is the same,
The portable audio player according to claim 5, wherein the first audio data and the second audio data are switched in a state where the audio electrodes and the output terminals of the audio signal generation circuit are connected to each other. The control circuit includes fifth and sixth nodes, and is operable by power supplied to any of the fifth and sixth nodes.
A power supply circuit that generates a voltage of a predetermined magnitude and supplies the voltage to the fifth node;
A battery for supplying power to the power supply circuit;
A power switch for electrically connecting or disconnecting the power circuit and the battery;
The portable audio player according to claim 1, further comprising: a voltage dividing circuit having an input terminal connected to the battery and an output terminal connected to the sixth node. The portable audio player according to claim 7, wherein the control circuit stores preliminary information by the power supplied from the sixth node before the operation is stopped when the power is turned off by the power switch. The portable audio player according to claim 8, wherein the preliminary information is a voltage of the sixth node. The portable audio player according to any one of claims 7 to 9, wherein the power switch is a mechanical switch. A power operation unit that can be operated from the outside of the housing is further provided.
The portable audio player according to claim 10, wherein the power operation unit is mechanically interlocked with the power switch.

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