JP2005064651A - Sound muting apparatus, sound muting method, and optical disk apparatus provided with sound muting apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reliably eliminate a pop noise sound at the application of power by a small number of components, prevent distortion in a sound output at sound reproduction and reduce current consumption. <P>SOLUTION: At the application of power, the level of a voltage V1 rises at a time constant comprising the resistance of a resistor R2 and the capacitance of a capacitor C1 in a second control circuit 2, the P-MOS transistor of the second control circuit 2 is turned on and the level of a voltage V2 rises to a high (H) level to turn on the transistor Tr1 of a first control circuit 1 from a time at the application of power until a prescribed time elapses, thereby interrupting an input line from a sound amplifier to a speaker and preventing a pop noise sound outputted from the sound amplifier at the application of power from intruding to the speaker. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an audio mute device such as an audio circuit for muting (mute) audio, an audio mute method thereof, and an optical disk device such as a CD-R / RW disc device and a DVD disc device provided with the audio mute device.

FIG. 11 is a block diagram showing a configuration of an audio sound mute circuit, and FIG. 12 is a waveform diagram showing output levels of respective parts of the sound mute circuit shown in FIG.
This audio mute circuit is configured to mute the sound when the mute signal = low (L) and output the sound when the mute signal = high (H).
As a countermeasure against popping noise when the power is turned on, when the power is turned on, the junction field effect transistor (junction FET: P-JFET1) is turned on, and a current flows from the output line of the audio amplifier circuit (audio amplifier) to the GND. I try to flow.
However, the junction-type FET: P-JFET 1 shown in FIG. That is, the pop sound cannot be completely removed when the power is turned on.

Therefore, an audio mute circuit as shown in FIG. 13 is also considered. FIG. 14 is a waveform diagram showing the output level of each part of the audio mute circuit shown in FIG.
The audio mute circuit shown in FIG. 13 uses an NPN transistor Tr1 instead of a junction FET. As in the above, the basic operation is to mute the sound when the mute signal = low (L), and output the sound when the mute signal = high (H).
As a countermeasure against popping noise when the power is turned on, when the power is turned on, V1 = L level and the transistor Tr2 is turned on (ON), and V2 = high (H) level and the transistor Tr1 is turned on (ON). A current is allowed to flow from the output line of the amplifier circuit (sound amplifier) to GND.

The NPN transistor Tr1 has a lower ON resistance than that of the junction FET, so that a sufficient current can flow from the output line of the audio amplifier to the GND.
Therefore, the audio mute circuit shown in FIG. 13 can sufficiently take measures against pop noise when the power is turned on.
However, the audio mute circuit of FIG. 13 has a problem that the audio output is distorted during audio reproduction.
This is because when V2 = GND during audio reproduction, when a negative voltage is applied to V3, the diode between the base and collector of the NPN transistor Tr1 is in the forward direction and is lower than the voltage applied to the collector. The voltage is not applied, and the output waveform is distorted in the same manner as the lower limiter is inserted.

Conventionally, an audio mute circuit shown in FIG. 15 has been considered in order to solve these two problems. FIG. 16 is a waveform diagram showing output levels at various parts of the audio mute circuit shown in FIG.
In the audio mute circuit shown in FIG. 15, as in the audio mute circuit described above, the audio is muted when the mute signal = low (L), the audio is output when the mute signal = high (H), and the power is turned on. As a countermeasure against pop noise, when the power is turned on, a high (H) level signal is output from the mute signal, but the voltage level of V1 is only gradually increased by the integration circuit of the resistor R2 and the capacitor C2. Therefore, immediately after the power is turned on, the field effect transistor FET1 is off (OFF), and V2 = high (H) level, and the transistor Tr1 is turned on to take measures against pop noise.
Then, as time goes on since the power is turned on, the capacitor C2 is charged, the voltage level of V1 rises, the field effect transistor FET1 is turned on, and V2 = low (L) level. The transistor TR1 is turned off (OFF) so that sound can be reproduced.

That is, the sound mute circuit shown in FIG. 15 delays the rise of the voltage V1 by the integration circuit of the resistor R2 and the capacitor C2 from the power-on and delays the field-effect transistor FET1 from being turned on. This is a circuit that eliminates the pop sound by creating a time period during which the field effect transistor FET11 is turned on, and automatically enables the sound reproduction after the field effect transistor FET11 is turned on.
In this circuit, if the time constant is sufficient for the pop noise countermeasure, the pop noise countermeasure can be sufficiently performed. Further, C1 is inserted as a countermeasure against the problem that the audio output is distorted during audio reproduction. In this way, countermeasures against pop noise when power is turned on and countermeasures against distortion of audio output during voice reproduction are performed (for example, see Patent Document 1).
JP-A-9-46149

However, in the audio mute circuit described above, when a capacitor having a capacity larger than that of the capacitor C1 is inserted in the output of the audio circuit, there is a problem that the capacitor C1 cannot completely absorb the pop sound generated when the power is turned on.
If the capacitance of the capacitor C1 is increased to prevent this, pop noise can be absorbed, but there is a problem that pop noise is generated again when electric charge is stored in the capacitor C4. At the time of audio reproduction, current continues to flow in the path of power source → resistor R1 → ON resistance of the field effect transistor FET1 → GND or path of power source → resistor R1 → base / emitter of the transistor Tr1 → GND.
The present invention has been made in view of the above points, and can reliably eliminate pop noise when power is turned on with a smaller number of parts, prevent distortion of audio output during audio reproduction, and reduce current consumption. The purpose is to.

In order to achieve the above object, the present invention provides the following audio muting devices (1) to (4).
(1) First control means for controlling whether or not the sound signal amplified by the amplification means is input to the sound output means, and second control means for switching the control of the first control means are provided. The second control means controls to switch the control so that the first control means does not input the audio signal to the audio output means from when the amplifier means is powered on until a predetermined time, After a predetermined time, the first control means switches to control to input the audio signal to the audio output means, and the first control means is switched by the second control means. Control is performed so that the audio signal is not input to the audio output means in order to eliminate the pop sound generated when the amplification means is turned on for a predetermined time from when the amplification means is turned on. After a predetermined time audio mute unit is a means for controlling so as to input the audio signal to the audio output means.
(2) In the audio mute device of (1), the second control unit is stopped in order to prevent a reverse flow of current from the first control unit with respect to the negative voltage of the audio signal during audio reproduction. A sound mute device provided with third control means for controlling the sound.

(3) a first control means for controlling whether or not to input the audio signal amplified by the amplifying means to the audio output means; a second control means for switching the control of the first control means; The second control means has a third control means for controlling the switching control operation of the second control means, and the third control means is configured such that the second control means is the first control during the CPU reset after the power is turned on. The control means is controlled to switch to control for inputting the audio signal to the audio output means, and when the CPU reset is released, the second control means controls the first control means. Control is performed so as to switch the control so that the sound signal is not input to the sound output means, and the second control means sends the sound signal to the first control means based on a sound reproduction instruction from the CPU. Voice output hand The second control means controls the input to the control to be input to the CPU during the resetting of the CPU after the power is turned on and the voice reproduction instruction from the CPU by the control from the third control means. Is switched to control that causes the first control means to input the audio signal to the audio output means, and when the CPU reset is released, the first control means causes the audio signal to be input. Is controlled to prevent the sound from being input to the sound output means, and the first control means is controlled by the second control means to the sound output means during the CPU reset by the control from the second control means. The audio signal is controlled to be input, and when the CPU reset is released, the sound is deleted to remove the pop sound generated when the CPU reset is released. Controlled so as not to enter the audio signal to the output means, audio muting device when for which the audio reproduction instruction is means for controlling so as to input the audio signal to the audio output means from the CPU.

(4) First control means for controlling whether or not the sound signal amplified by the amplification means is input to the sound output means, and second control means for switching the control of the first control means. The second control means controls to switch the control so that the first control means does not input the audio signal to the audio output means within a predetermined time from when the power is turned on, and reproduces the audio from the CPU. When instructed, the first control means switches to control that causes the audio signal to be input to the audio output means, and the first control means controls the audio from the time of power-off until a predetermined time. The first control means controls the control so as not to input a signal to the sound output means, and the first control means performs the switching control by the second control means until a predetermined time from power-on. The first control means controls so that the audio signal is not input to the audio output means, and when there is an audio reproduction instruction from the CPU, the first control means sends the audio signal to the audio output means. An audio mute device which is a means for controlling the input so that the first control means does not input the audio signal to the audio output means from the time of power-off until a predetermined time.

The following audio muting methods (5) to (8) are also provided.
(5) From the first control step for controlling whether or not to input the audio signal amplified by the amplifying unit to the audio output unit, and the second control step for switching and controlling the control of the first control step The second control step switches to control that prevents the audio signal from being input to the audio output unit in the first control step from when the power of the amplifying unit is turned on to a predetermined time. After the predetermined time, the first control step is a step of switching control to control the voice signal to be input to the voice output means, and the first control step is a switching by the second control step. Control is performed so that the audio signal is not input to the audio output means from the time when the amplification means is turned on until a predetermined time from the time when the amplification means is turned on in order to delete the pop sound. The predetermined time after the audio muting process is a step of controlling so as to input the audio signal to the audio output means.
(6) In the audio mute method according to (5), the second control step is stopped in order to prevent a backflow of current in the first control step with respect to the negative voltage of the audio signal during audio reproduction. A sound mute method provided with a third control step for controlling the sound.

(7) a first control step for controlling whether or not to input the audio signal amplified by the amplifying unit to the audio output unit, and a second control step for switching and controlling the control of the first control step; A third control step for controlling the switching control operation of the second control step. The third control step is performed by the second control step during the CPU reset after the power is turned on. In the control step, control is performed so as to switch to control for inputting the audio signal to the audio output means, and when the CPU reset is released, the audio signal is output in the first control step by the second control step. Control is performed so as to switch to control that does not input to the audio output means, and the audio signal is output by the first control means by the second control step based on an audio reproduction instruction from the CPU. The second control step is a step of controlling to switch to the control to be input to the means, and the second control step is during the CPU reset after the power is turned on by the control of the third control step and the voice reproduction instruction from the CPU Is switched to control that causes the audio signal to be input to the audio output means in the first control step, and when the CPU reset is released, the audio signal is input in the first control step. Is controlled so as not to be input to the audio output means, and the first control step is the control of the second control step, and the audio output means is supplied to the audio output means during the CPU reset. When the CPU reset is released, the audio output is used to delete the pop sound generated when the CPU reset is released. Controlled so as not to enter the audio signal to the unit, audio muting process upon for which the audio reproduction instruction from the CPU is a step of controlling so as to input the audio signal to the audio output means.

(8) From the first control step for controlling whether or not to input the audio signal amplified by the amplifying unit to the audio output unit, and the second control step for switching and controlling the control of the first control step. In the second control step, the control is switched to control that prevents the audio signal from being input to the audio output means in the first control step from the time of power-on to a predetermined time, and the audio reproduction from the CPU is performed. When instructed, in the first control step, control is performed to switch the control so that the audio signal is input to the audio output means, and from the time the power is turned off until the predetermined time, the audio signal is input in the first control step. This is a step of switching control to prevent the signal from being input to the audio output means, and the first control step is a period of time from when the power is turned on by the switching control by the second control step. In the first control step, the audio signal is controlled not to be input to the audio output means. When an audio reproduction instruction is issued from the CPU, the audio signal is output in the first control step. An audio mute method, which is a step of controlling the audio signal not to be input to the audio output means in the first control step from the time of power-off until a predetermined time.

Furthermore, the following optical disk device (9) is also provided.
(9) An optical disc device comprising the audio mute device according to any one of (1) to (4).

  The optical mute apparatus, the audio mute method, and the audio mute apparatus according to the present invention can reliably remove pop noise when the power is turned on with a smaller number of parts, prevent audio output distortion during audio reproduction, and Current consumption can be reduced.

Embodiments of the present invention will be specifically described below with reference to the drawings.
[Example 1]
FIG. 2 is a diagram showing a schematic configuration of an information processing apparatus using an optical disc apparatus according to an embodiment of the present invention.
This information processing apparatus includes an optical disk device (optical disk drive) 10 and a host computer 11.
The host computer 11 is a device such as a personal computer including an input device 12 such as a keyboard and a mouse, a display device 13 such as a CRT and an LCD, and a CPU 14.

  The optical disk apparatus 10 includes MD, MO, CD, CD-ROM, CD-R disk, CD-RW disk, CD + R disk, CD + RW disk, DVD-R disk, DVD + R disk, DVD-RW disk, DVD + RW disk, DVD-RAM. This is a device for recording a large amount of information on an optical disc (recording medium) such as a disc, a DVD + RAM disc, or reproducing information recorded on the optical disc.

For example, the CD-R disc and the CD-RW disc are writable (recordable) CDs (compact discs), and the former CD-R (CD recordable) disc can be written only once. CD (also referred to as CD-Write Once). The latter CD-RW (CD rewritable) disc is a CD that can be written a plurality of times (also referred to as CD-E (CD erasable)).
These CD-R discs and CD-WR discs, that is, optical discs, are recorded and reproduced by an optical disc 10 having a configuration as shown in FIG.

FIG. 3 is a block diagram showing a configuration of the optical disc apparatus shown in FIG.
This optical disk apparatus corresponds to an optical disk apparatus according to an embodiment of the present invention provided with a mute circuit to be described later.
This optical disk apparatus 10 includes 50 an optical disk, 20 a spindle motor, 21 an optical pickup, 22 a motor driver, 23 a read amplifier, 24 a servo unit, 25 a CD decoder, 26 an ATIP decoder, 27 a laser controller, 28 is a CD encoder, 29 is a CD-ROM encoder, 30 is a buffer RAM, 31 is a buffer manager, 32 is a CD-ROM decoder, 33 is an ATAPI / SCSI interface, 34 is a D / A converter, 35 is a ROM, and 36 is a CPU. , 37 is a RAM, 38 is an audio amplifier (amplifier circuit), 39 is a speaker, 40 is an audio mute circuit, and L is a laser beam.
In FIG. 3, the arrows indicate the directions in which data mainly flow, and in order to simplify the drawing, the CPU 36 that controls each block in FIG. 3 and the connection between the blocks are not shown. .

Next, the operation of this optical disc apparatus will be described.
The optical disk 50 is rotationally driven by the spindle motor 20. The spindle motor 20 is controlled by the motor driver 22 and the servo unit 24 so that the linear velocity is constant. This linear velocity can be changed stepwise.
The optical pickup 21 includes a semiconductor laser light source (LD) such as a known laser diode (not shown), an optical system, a focus actuator, a track actuator, a light receiving element, and a position sensor, and irradiates the optical disk 50 with the laser light L. To do.
The optical pickup 21 can be moved in the sledge direction by a seek motor. These focus actuator, track actuator, and seek motor are positioned at a target location on the optical disk 50 by the motor driver 22 and the servo unit 24 based on signals obtained from the light receiving element and the position sensor. To be controlled.

At the time of reading (information reproduction), a reproduction signal obtained by the optical pickup 21 is amplified and binarized by the read amplifier 23 and then input to the CD decoder 25. The input binary data is demodulated by the CD decoder 25 by EFM (Eight to Fourteen Modulation).
Note that the recording data is EFM modulated by collecting 8 bits at a time. In this EFM modulation, 8 bits are converted to 14 bits, and 3 bits are added to form a combined bit to make a total of 17 bits. In this case, the combined bits are attached so that the number of previous “1” s and “0” s are equal on average. This is called “DC component suppression”, and the slice level fluctuation of the DC-cut reproduction signal is suppressed.

The demodulated data is subjected to deinterleaving and error correction. Thereafter, this data is input to the CD-ROM decoder 32, and further error correction processing is performed in order to increase the reliability of the data.
The data that has been subjected to the error correction processing twice as described above is temporarily stored in the buffer RAM 30 by the buffer manager 31 and is arranged as sector data in the host via the ATAPI / SCSI interface (I / F) 33. It is transferred at once to a computer (personal computer).
In the case of audio data including music data, the data output from the CD decoder 25 is input to the D / A converter 34 and extracted as an analog audio signal (audio signal (audio)).

The audio signal output from the D / A converter 34 is amplified by an audio amplifier (amplifying circuit: amplification means) 38, input to a speaker (audio output means) 39, and output from the speaker 39 as audio. The audio mute circuit 40 is provided on the input line from the audio amplifier 38 to the speaker 39, and removes pop sounds when the power is turned on, when the CPU reset is released, and when the power is turned off.
At the time of writing (information recording), data sent from the host computer through the ATAPI / SCSI I / F 33 is temporarily stored in the buffer RAM 30 by the buffer manager 31.

The write operation is started in a state where a certain amount of data is accumulated in the buffer RAM 30. In this case, the laser spot needs to be positioned at the write start point before that. This point is obtained by a wobble signal preliminarily engraved on the optical disc 50 by the meandering of the track.
The wobble signal includes absolute time information called ATIP, and this information is extracted by the ATIP decoder 26. Further, the synchronization signal generated by the ATIP decoder 26 is input to the CD encoder 28, and data can be written at an accurate position on the optical disk 50. Data in the buffer RAM 30 is added to the error correction code and interleaved by the CD-ROM encoder 29 and the CD encoder 28, and is recorded on the optical disk 50 via the laser controller 27 and the optical pickup 21.

  The EFM modulated data drives the laser as a bit stream at a channel bit rate of 4.3218 Mbps (standard speed). The recording data in this case constitutes an EFM frame in units of 588 channel bits. The channel clock means a clock having a frequency of this channel bit.

Next, the audio mute circuit 40 of the optical disc apparatus will be described.
FIG. 1 is a block diagram showing a configuration of the audio mute circuit 40 shown in FIG.
The audio mute circuit 40 includes a first control circuit 1 (corresponding to the first control means of claim 1) comprising a transistor Tr1 and a resistor R1, and a second control circuit comprising a P-MOS, a resistor R2, and a capacitor C1. Control circuit 2 (corresponding to the second control means of claim 1), and fulfills the function of the audio mute device according to claim 1 of the present invention.
The audio mute circuit 40 can mute (mute) the sound from the speaker when the mute signal = low (L), and output the sound from the speaker when the mute signal = high (H). Yes. In this audio mute circuit, the P-MOS is turned off during audio reproduction, so that no current flows anywhere.

  As a countermeasure against pop sound mute when power is turned on (power input, power on), the voltage level of V1 rises due to the time constant of the resistor R2 and capacitor C1 of the second control circuit 2 when power is turned on. Therefore, immediately after the power is input, the P-MOS of the second control circuit 2 is on (ON) and becomes V2 = high (H) level, and the transistor of the first control circuit 1 from the time of power-on to a predetermined time. Tr1 is turned on (second control step of claim 5). The transistor Tr1 of the first control circuit 1 is turned on for a predetermined time after the power is turned on to cut off the input line from the voice amplifier to the speaker, and the pop sound output from the voice amplifier when the power is turned on is not input to the speaker. (First control step of claim 5).

As time elapses after the power is turned on, the capacitor C1 of the first control circuit 1 is charged, the voltage level of V1 increases, and the P-MOS of the second control circuit 2 is turned off. , V2 = Low (L) level, and the transistor Tr1 of the first control circuit 1 is turned off (OFF) so that the audio signal can be input from the audio amplifier to the speaker.
In other words, in the audio mute circuit 40, the transistor Tr1 is turned on after the power is turned on by delaying the voltage rise of the V1 by the integration circuit of the resistor R2 and the capacitor C2 from turning on the power and delaying the P-MOS being turned off. Time can be taken to remove the pop sound, and after P-MOS is turned off, the sound can be automatically reproduced.

Here, if the time constant is sufficient for the pop noise countermeasure, the pop noise countermeasure can be sufficiently performed.
In this way, if it is not necessary to mute the sound during playback, the circuit can be muted by turning on the transistor Tr1 only when the power is turned on, without controlling the second control circuit 2 by the CPU. After the power is turned on, the voice can be automatically played back.

Next, another audio mute circuit according to the present invention will be described.
FIG. 4 is a block diagram showing a configuration example of another audio mute circuit according to the present invention.
FIG. 5 is a waveform diagram showing changes in signal levels at various points in the audio mute circuit shown in FIG.
The audio mute circuit 41 includes a first control circuit 3 (corresponding to the first control means of claim 2) comprising a transistor Tr1 and a resistor R1, and a second control circuit comprising a P-MOS, a resistor R2, and a capacitor C1. Control circuit 4 (corresponding to the second control means of claim 2) and a CPU 36 (corresponding to the third control means of claim 2).
With such a circuit configuration, power saving and a reduction in the number of components are realized while taking countermeasures against pop sound mute when power is turned on and distortion when reproducing sound.

The audio mute circuit 41 can mute (mute) the sound from the speaker when the mute signal = low (L), and output the sound from the speaker when the mute signal = high (H). Yes. In this audio mute circuit, the P-MOS is turned off during audio reproduction, so that no current flows anywhere.
As a measure against pop sound mute when the power is turned on (power input, power on), the voltage level of V1 rises with the time constant of the resistor R2 and the capacitor C1 of the second control circuit 4 when the power is turned on. Therefore, immediately after the power is input, the P-MOS of the second control circuit 4 is turned on (ON) and becomes V2 = high (H) level, and the transistor of the first control circuit 3 is turned on for a predetermined time after the power is turned on. Tr1 is turned on (second control step of claim 6).
The transistor Tr1 of the first control circuit 3 is turned on for a predetermined time from when the power is turned on to cut off the input line from the voice amplifier to the speaker, and does not input the pop sound output from the voice amplifier when the power is turned on to the speaker. (First control step of claim 6).

As time elapses after the power is turned on, the capacitor C1 of the first control circuit 3 is charged with a charge, the voltage level of V1 rises, and the P-MOS of the second control circuit 4 is turned off. V2 = Low (L) level, the transistor Tr1 of the first control circuit 3 is turned off (OFF), and a sound signal can be reproduced by inputting a sound signal from the sound amplifier to the speaker.
In other words, in the audio mute circuit 41, the transistor Tr1 is turned on after the power is turned on by delaying the voltage rise of the V1 by the integration circuit of the resistor R2 and the capacitor C2 from the power on and delaying the P-MOS from being turned off. Time can be taken to remove the pop sound, and after the P-MOS is turned off, the voice can be automatically reproduced. Here, if the time constant is sufficient for the pop noise countermeasure, the pop noise countermeasure can be sufficiently performed.

Further, as a countermeasure against the problem that the audio output is distorted during the audio reproduction, the CPU 36 turns off the P-MOS of the second control circuit 4 by the mute signal during the audio reproduction so that the V2 line is completely changed to the other. By separating the circuit from the circuit (third control step of claim 6), even if a negative voltage is applied to V3, the diode between the base and collector of the transistor Tr1 of the first control circuit 3 is in the forward direction. Thus, the lower limiter is prevented from being generated, and the backflow of current from the first control circuit 3 to the second control circuit 4 can be prevented.
In this way, measures are taken against pop sound mute when power is turned on and sound output distortion when sound is reproduced.
Therefore, according to the audio mute circuit 41, it is possible to remove pop noise when the power is turned on with a minimum necessary circuit configuration with a smaller number of parts, and it is possible to prevent audio output distortion during audio reproduction. The current consumption of the mute circuit during audio reproduction can be reduced to zero.

Next, still another audio mute circuit according to the present invention will be described.
The main pop sound at power-on occurs at the moment when the CPU reset of the CPU 36 is released after power-on. For this reason, when it is necessary to reset the CPU for a long time, there is a possibility that the pop sound cannot be completely removed by the time constant generated by the capacitor C1 and the resistor R2 of the audio mute circuit.
In that case, the pop circuit at the time of power-on can be surely removed by using the following circuit configuration.

FIG. 6 is a block diagram showing a configuration example of still another audio mute circuit according to the present invention.
FIG. 7 is a waveform diagram showing changes in signal levels at various points in the audio mute circuit shown in FIG.
The audio mute circuit 42 includes a first control circuit 5 (corresponding to the first control means of claim 3) comprising a transistor Tr1 and a resistor R1, and a second control circuit comprising a P-MOS and a resistor R2. 6 (corresponding to the second control means of the third aspect) and a third control circuit (corresponding to the third control means of the third aspect) comprising a CPU 36, an OR circuit and an inverter 7. Has been.

The audio mute circuit 42 can mute audio from the speaker when the mute signal = low (L), and output audio from the speaker when the mute signal = high (H).
As a countermeasure against pop sound mute when the power is turned on (power input, power on), when the power is turned on, the CPU reset signal output from the CPU 36 in the third control circuit 7 becomes a low (L) level, and the CPU after the power is turned on. In the case of resetting (CPU resetting when the CPU reset signal is L), V3 becomes high (H) via the inverter and the OR circuit (third control step of claim 7), and at this time The P-MOS of the second control circuit 6 is turned off (second control step of claim 7), the transistor Tr1 of the first control circuit 5 is turned off, and an audio signal is input from the audio amplifier to the speaker. In this way, the sound can be reproduced (first control step of claim 7).

Thereafter, the CPU reset signal becomes high (H) (CPU reset release), and the voltage level of V3 becomes low (L) accordingly (third control step of claim 7), and the second control circuit 6 The P-MOS is turned on (second control step of claim 7), and the transistor Tr1 of the first control circuit 5 is turned on.
When the CPU reset is released, the transistor Tr1 of the first control circuit 5 is turned on to cut off the input line from the audio amplifier to the speaker so that the pop sound generated when the CPU reset is released is not input to the speaker. Item 7 first control step).
In this way, it is possible to take a countermeasure against the pop sound mute at the moment when the CPU reset is released.

Further, if the mute signal is set to high (H) from the CPU 36 of the third control circuit 7 after the pop sound has disappeared (voice reproduction instruction), V3 becomes high (H) via the OR circuit (invoice). (Third control step of item 7), the P-MOS of the second control circuit 6 is turned off (second control step of claim 7), the transistor Tr1 of the first control circuit 5 is turned off, and the voice The audio reproduction can be performed by inputting the audio signal from the amplifier to the speaker (first control step of claim 7).
In this way, according to the audio mute circuit 42, it is possible to reliably remove the pop sound caused by the CPU reset release when the power is turned on.

Next, still another audio mute circuit according to the present invention will be described.
In addition to turning on the power, it is possible to take a mute pop noise countermeasure when the power is turned off (power off).
FIG. 8 is a block diagram showing a configuration example of still another audio mute circuit according to the present invention.
FIG. 9 is a waveform diagram showing changes in signal levels at various points when the power is turned off in the audio mute circuit shown in FIG.
FIG. 10 is a waveform diagram showing changes in signal levels at various points when the power is turned on in the audio mute circuit shown in FIG.

The audio mute circuit 43 includes a first control circuit 8 (corresponding to the first control means of claim 4) comprising a transistor Tr1 and a resistor R1, a P-MOS, a capacitor C1, a resistor R2, and a resistor R3. And a second control circuit 9.
The audio mute circuit 43 is configured to mute the sound from the speaker when the mute signal = low (L), and output the sound from the speaker when the mute signal = high (H).
As a countermeasure against pop sound mute when the power is turned off (power is turned off) (see FIG. 9), the voltage level of V1 decreases as the power supply voltage decreases when the power is turned off.

However, the voltage level of V2 decreases while taking time corresponding to the time constant of the resistor R2 and the capacitor C1 of the second control circuit 9. Therefore, even after the power is turned off, as indicated by V3 in FIG. 9, it is possible to make a time during which the P-MOS of the second control circuit 9 is on.
Then, when the P-MOS of the second control circuit 9 is turned on (second control step of claim 8), the transistor Tr1 of the first control circuit 8 is turned on, and the first control circuit 5 When the transistor Tr1 is turned on, the input line from the audio amplifier to the speaker is cut off, so that the pop sound generated when the power is turned off is not input to the speaker (first control step of claim 8).

As a countermeasure against pop sound mute when the power is turned on (see FIG. 10), when the power is turned on, the voltage level of V2 is increased by the time constant of the resistor R2 and the capacitor C1 of the second control circuit 9.
Therefore, immediately after the power is turned on, the P-MOS of the second control circuit 9 is turned off, but the voltage level of V2 gradually rises and the P-MOS is turned on (second control of claim 8). Step), when the voltage V2 is transmitted to V3 and the transistor Tr1 of the first control circuit 8 is turned on, the input line from the voice amplifier to the speaker is cut off, and the pop sound generated when the power is turned on is not input to the speaker. (First control step of claim 8).

  Then, after the pop sound disappears, if the mute signal of the CPU 36 is set to high (H) (audio reproduction instruction), the P-MOS of the second control circuit 6 is turned off (second control step of claim 8). ), The transistor Tr1 of the first control circuit 5 is turned off, and a sound signal can be reproduced by inputting a sound signal from the sound amplifier to the speaker (first control step of claim 8).

Further, as a countermeasure against the problem that the audio output is distorted during the audio reproduction, the CPU 36 turns off the P-MOS of the second control circuit 9 by the mute signal during the audio reproduction so that the V2 line is completely changed to the other. By separating the circuit from the circuit (second control step of claim 8), even if a negative voltage is applied to V3, the diode between the base and collector of the transistor Tr1 of the first control circuit 8 is in the forward direction. Thus, the lower limiter is prevented from being generated, and the backflow of current from the first control circuit 8 to the second control circuit 9 can be prevented.
In this way, measures are taken not only when the power is turned on but also when the power is turned off.

  The audio mute apparatus, the audio mute method, and the audio mute apparatus according to the present invention can also be applied to personal computers such as desktop personal computers and notebook personal computers.

It is a block diagram which shows the structure of the audio | voice mute circuit 40 shown in FIG. It is a figure which shows schematic structure of the information processing apparatus using the optical disk device which is one Embodiment of this invention. FIG. 3 is a block diagram showing a configuration of the optical disc apparatus shown in FIG. 2. It is a block diagram which shows the structural example of the other audio | voice mute circuit based on this invention. FIG. 5 is a waveform diagram showing changes in signal levels at various points in the audio mute circuit shown in FIG. 4. It is a block diagram which shows the structural example of the another audio | voice mute circuit based on this invention. FIG. 7 is a waveform diagram showing changes in signal levels at various points in the audio mute circuit shown in FIG. 6. It is a block diagram which shows the structural example of the other audio | voice mute circuit based on this invention. It is a wave form diagram which shows the change of the signal level of each place at the time of power-off in the audio | voice mute circuit shown in FIG. It is a wave form diagram which shows the change of the signal level of each place at the time of power activation in the audio | voice mute circuit shown in FIG. It is a block diagram which shows the structure of the conventional audio | voice mute circuit. It is a wave form diagram which shows the output level of each part of the conventional audio | voice mute circuit shown in FIG. It is a block diagram which shows the structure of the other conventional audio | voice mute circuit. It is a wave form diagram which shows the output level of each part of the conventional audio | voice mute circuit shown in FIG. It is a block diagram which shows the structure of the other conventional audio | voice mute circuit. FIG. 16 is a waveform diagram showing output levels of respective parts of the conventional audio mute circuit shown in FIG. 15.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 3, 5, 8: 1st control circuit 2, 4, 6, 9: 2nd control circuit 7: 3rd control circuit 10: Optical disk apparatus 11: Host computer 12: Input apparatus 13: Display apparatus 14 : CPU 20: Spindle motor 21: Optical pickup 22: Motor driver 23: Read amplifier 24: Servo unit 25: CD decoder 26: ATIP decoder 27: Laser controller 28: CD encoder 29: CD-ROM encoder 30: Buffer RAM 31: Buffer manager 32: CD-ROM decoder 33: ATAPI / SCSI interface 34: D / A converter 35: ROM 36: CPU 37: RAM 38: Audio amplifier (amplifier circuit) 39: Speakers 40, 41, 4 2, 43: Audio mute circuit 50: Optical disc

Claims (9)

A first control unit that controls whether or not to input the audio signal amplified by the amplification unit to the audio output unit; and a second control unit that switches and controls the control of the first control unit;
The second control means controls to switch the control so that the first control means does not input the audio signal to the audio output means until a predetermined time from when the amplification means is turned on. Thereafter, the first control means is a means for switching control to control the audio signal to be input to the audio output means,
The first control unit is configured to delete the pop sound generated when the amplification unit is turned on for a predetermined time from when the amplification unit is turned on by switching control by the second control unit. The audio mute apparatus controls the audio signal so that the audio signal is not input to the audio output unit and controls the audio output unit to input the audio signal after the predetermined time. The audio mute device according to claim 1,
Third control means is provided for controlling the second control means to be stopped in order to prevent backflow of current from the first control means with respect to the negative voltage of the audio signal during audio reproduction. A featured audio mute device. A first control means for controlling whether or not to input the audio signal amplified by the amplifying means to the audio output means; a second control means for switching control of the control of the first control means; and the second control means. And third control means for controlling the switching control operation of the control means,
The third control means switches the control to switch the first control means to input the audio signal to the audio output means during the CPU reset after the power is turned on. And when the CPU reset is released, the second control means controls the first control means so as to switch the control so as not to input the audio signal to the audio output means. The second control means controls the first control means to switch to control to input the audio signal to the audio output means based on the audio reproduction instruction of
The second control means is configured such that when the CPU is reset after the power is turned on by the control from the third control means and when there is an audio reproduction instruction from the CPU, the first control means Is switched to control that causes the audio output means to be input to the audio output means, and when the CPU reset is released, the first control means switches to control that prevents the audio signal from being input to the audio output means. Means to
The first control unit controls the audio output unit to input the audio signal during the CPU reset by the control from the second control unit, and the CPU reset when the CPU reset is released. In order to delete the pop sound generated at the time of release, control is performed so that the audio signal is not input to the audio output means, and the audio signal is input to the audio output means when there is an audio reproduction instruction from the CPU. An audio mute device characterized in that it is a means for controlling as described above. A first control unit that controls whether or not to input the audio signal amplified by the amplification unit to the audio output unit; and a second control unit that switches and controls the control of the first control unit;
The second control means controls to switch the control so that the first control means does not input the audio signal to the audio output means between the time of power-on and a predetermined time, and receives an audio reproduction instruction from the CPU. When there is, the first control means controls to switch the control so that the audio signal is input to the audio output means, and the first control means outputs the audio signal from the time of power-off until a predetermined time. It is means for switching control to control not to input to the audio output means,
The first control means controls the first control means so as not to input the audio signal to the audio output means from the time of power-on to a predetermined time by switching control by the second control means, and the CPU The first control means controls the audio signal to be input to the audio output means when an audio reproduction instruction is received from the first, and the first control means causes the audio signal to be input from the time of power-off until a predetermined time. An audio mute apparatus, characterized in that it is means for controlling a signal not to be input to the audio output means. A first control step for controlling whether or not to input the audio signal amplified by the amplifying unit to the audio output unit, and a second control step for switching and controlling the control of the first control step,
In the second control step, switching control is performed so that the audio signal is not input to the audio output unit in the first control step from when the power of the amplifying unit is turned on until a predetermined time, and the predetermined time The latter is a step of controlling to switch to a control for inputting the audio signal to the audio output means in the first control step,
In the first control step, the audio output means is used to delete a pop sound generated when the amplification means is turned on for a predetermined time from when the amplification means is turned on by switching control in the second control step. The audio mute method is a step of controlling so that the audio signal is not input to the audio signal and controlling the audio output means to input the audio signal after the predetermined time. The audio mute method according to claim 5, wherein
In order to prevent a backflow of current in the first control step with respect to the negative voltage of the audio signal during sound reproduction, a third control step is provided for controlling the second control step to a stop state. A feature of audio mute. A first control step for controlling whether or not to input the audio signal amplified by the amplifying unit to the audio output unit, a second control step for switching control of the control of the first control step, and the second A third control step for controlling the operation of switching control of the control step,
In the third control step, the CPU is controlled so as to switch to the control in which the audio signal is input to the audio output means in the first control step during the CPU reset after the power is turned on. When the CPU reset is released, the second control step is controlled so as to switch the control so that the audio signal is not input to the audio output means in the first control step, and the audio reproduction instruction from the CPU Based on the second control step, the first control means to control to switch to control to input the audio signal to the audio output means,
In the second control step, when the CPU is reset after the power is turned on by the control of the third control step and when there is an audio reproduction instruction from the CPU, the audio signal is output in the first control step. Control is switched to control to input to the voice output means, and control to switch to control to prevent the voice signal from being input to the voice output means in the first control step when the CPU reset is released. Process,
The first control step controls the audio output means to input the audio signal during the CPU reset by the control of the second control step, and releases the CPU reset when the CPU reset is released. In order to eliminate pop sounds that sometimes occur, control is performed so that the audio signal is not input to the audio output unit, and when the audio reproduction instruction is issued from the CPU, the audio signal is input to the audio output unit. A method for muting audio, characterized in that the method is a step of controlling the sound. A first control step for controlling whether or not to input the audio signal amplified by the amplifying unit to the audio output unit, and a second control step for switching and controlling the control of the first control step,
In the second control step, switching control is performed so that the audio signal is not input to the audio output means in the first control step within a predetermined time from when the power is turned on. If there is, the control is switched to the control that causes the audio signal to be input to the audio output means in the first control step, and the audio signal is output in the first control step from the time of power-off until a predetermined time. A step of switching control to control not to input to the audio output means,
In the first control step, control is performed so that the audio signal is not input to the audio output means in the first control step from the time of power-on to a predetermined time by switching control in the second control step, and the CPU When there is an audio reproduction instruction from the control unit, the audio signal is controlled to be input to the audio output means in the first control step, and the audio signal is output in the first control step from the time of power-off until a predetermined time. An audio mute method comprising a step of controlling so as not to input a signal to the audio output means.   An optical disc device comprising the audio mute device according to claim 1.

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