JP3819687B2 - Audio recording device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an audio recording apparatus, and more particularly to an audio recording apparatus that records an audio signal by an optical pickup in each of a plurality of recording areas discretely distributed on a disk recording medium.
[0002]
[Prior art]
In this type of disk device, when a predetermined signal is read from or written to a disk recording medium, recording areas {circle around (1)} to {circle around (7)} distributed discretely on the magneto-optical disk as shown in FIG. Access ▼. When accessing the recording area, the optical pickup is moved in the radial direction of the magneto-optical disk 34 by the seek operation and reaches the track where the target recording area exists. When the optical pickup moves by this seek operation, the tracking servo is off and the focus servo is on.
[0003]
A tracking error signal (hereinafter referred to as “TE signal”) and a focus error signal (hereinafter referred to as “FE signal”) for controlling the tracking servo and focus servo are shown in FIG. Is generated based on the reflected light of the three laser beams 46a, 46b, and 46c irradiated to the land track (L in FIG. 17A) or the groove track (G in FIG. 17A) provided on the surface of . The laser light reflected from the surface of the magneto-optical disk 36 is received and photoelectrically converted by a photodetector 48 having a plurality of light receiving elements 48a to 48h as shown in FIG.
[0004]
The laser light 46b is divided into four parts, laser light A, laser light B, laser light C, and laser light D, and irradiated onto the surface of the magneto-optical disk 36, and the reflected light of each laser light is an alphabet of A to D. Light is received by the corresponding light receiving elements 48a, 48b, 48c and 48d, respectively.
[0005]
Similarly, the laser beam 46a and the laser beam 46c are respectively divided into laser beams E and F and laser beams G and H, and the reflected light of each laser beam is a corresponding light receiving element 48e of alphabets E to H. , 48f, 48g, and 48h, respectively.
[0006]
When the outputs from the light receiving elements 48a to 48h are represented by alphabets A to H, TE and FE are calculated by calculations based on Equations 1 and 2, respectively.
[0007]
[Expression 1]
TE = {(A + B) − (C + D)} − α {(E + H) − (F + G)}
However, α≈2.
[0008]
[Expression 2]
FE = (A + C)-(B + D)
[0009]
[Problems to be solved by the invention]
During the seek operation, the optical pickup exceeds a plurality of land tracks and groove tracks in the track width direction. Since the land track and the groove track have different reflectivities, light and darkness are generated at spots formed by the reflected light of the laser light 46b on the light receiving elements 48a, 48b, 48c and 48d. This brightness changes as shown in FIGS. 18A to 18B according to the movement of the optical pickup. The shaded portions in each of FIGS. 18A to 18B are dark portions of light and dark (the same applies in FIG. 19).
[0010]
As shown in FIG. 18, it is an ideal state that the spot shape is a perfect circle and the center of the spot coincides with the center of the light receiving elements 48a, 48b, 48c and 48d. Thus, when the spot is ideal, the value of the FE signal during the seek operation is always 0.
[0011]
However, even if the beam spot on the magneto-optical disk 36 is ideally narrowed due to assembly errors of the pickup optical system, the light distribution on the sensors (light receiving elements 48a, 48b, 48c and 48d) and the like are in the ideal state. May not be. In this case, the brightness of the spot of the laser beam during the seek operation shown in FIG. 18 also affects the focus detection (focus error signal), and the focus error signal is not always “0”.
[0012]
As shown in FIG. 19, the spot of the laser beam in the actual disk device is elliptical, and its center is deviated from the center of the sensors (light receiving elements 48a, 48b, 48c and 48d). Since the spot shape changes as shown in FIGS. 19A to 19B, the values of (A + C) and (B + D) in Equation 2 are not equal. Therefore, a signal waveform other than “0” appears in the FE signal during the seek operation. Further, since the center of the spot is shifted, the difference between the values of (A + B) and (B + D) is further increased, and the signal waveform appearing in the FE signal is further increased.
[0013]
Therefore, in an actual disk device, the FE signal at the time of seek operation includes a signal waveform that should not be generated. This signal waveform that should not occur originally in the FE signal is called a “TE leakage signal”. As described above, when the TE leakage signal is included in the FE signal, the optical pickup largely vibrates up and down by the focus servo based on the FE signal, and noise is generated.
[0014]
The optical pickup is connected to the sled motor by a rack and pinion state or the like. During the seek operation, the rotation of the sled motor is transmitted to the rack and pinion state, whereby the optical pickup is moved in the radial direction (inner circumferential direction and outer circumferential direction) of the magneto-optical disk 36 (sled movement). Accordingly, not only noise due to vibration of the optical pickup but also noise due to rotation of the sled motor and operation in the rack and pinion state is generated during the seek operation.
[0015]
For this reason, the conventional audio recording apparatus has a problem that noise generated during sled operation is picked up by a microphone during audio recording, and noise is mixed in an audio signal to be originally recorded.
[0016]
In order to solve this problem, there has been an audio recording apparatus that employs a method of blocking vibration generated from a noise source from being directly transmitted to a microphone. As a method for shutting off the noise source and the microphone, there is a method of attaching the microphone to the casing of the voice recording device through a cushioning material such as rubber or sponge.
[0017]
[Problems to be solved by the invention]
However, in the method of attaching the microphone to the casing of the voice recording apparatus via the cushioning material as in the conventional voice recording apparatus, noise due to vibration transmitted to the microphone can be prevented, but the noise is generated from the noise source. Noise generated by picking up noise by the microphone could not be removed.
[0018]
Therefore, a main object of the present invention is to provide an audio recording apparatus that can reduce the influence of seek noise picked up by a microphone on a recorded audio signal.
[0019]
[Means for Solving the Problems]
  An audio recording apparatus according to the invention of claim 1 is an audio recording apparatus for recording an audio signal by an optical pickup in a plurality of empty areas discretely formed on a disk recording medium. A writing means for temporarily writing the audio signal captured by the microphone into the buffer; and a moving means for moving the optical pickup for recording the audio signal stored in the buffer in each empty area. Includes an attenuating means for attenuating the audio signal when the optical pickup moves, and further comprising a discriminating means for discriminating the level of the audio signal captured by the microphone, and the attenuating means attenuates the audio signal according to the discrimination result of the discriminating means. And determining means for comparing the level of the audio signal with the first threshold every predetermined period. And a measuring means for measuring a level drop time during which the level of the audio signal is continuously below the first threshold, and the attenuating means attenuates the audio signal when the level drop time exceeds the second threshold. .
  An audio recording apparatus according to a second aspect of the present invention is a sound recording apparatus for recording an audio signal by an optical pickup in a plurality of empty areas discretely formed on a disk recording medium, and a microphone that continuously takes in an audio signal from the outside, A writing means for temporarily writing the audio signal captured by the microphone into the buffer; and a moving means for moving the optical pickup for recording the audio signal stored in the buffer in each empty area. Includes an attenuating means for attenuating the audio signal when the optical pickup moves, and further comprising a discriminating means for discriminating the level of the audio signal captured by the microphone, wherein the attenuating means attenuates the audio signal according to the discrimination result of the discriminating means The discriminating means repeatedly calculates the average level of the audio signal for a predetermined period, and the attenuation means And wherein the attenuating the audio signal when the average level is equal to or less than the third threshold value.
  According to a third aspect of the present invention, there is provided an audio recording apparatus for recording an audio signal by an optical pickup in a plurality of empty areas discretely formed on a disk recording medium, wherein the microphone continuously captures the audio signal from the outside, A writing means for temporarily writing the audio signal captured by the microphone into the buffer; and a moving means for moving the optical pickup for recording the audio signal stored in the buffer in each empty area. Attenuating means for attenuating the audio signal when the optical pickup is moved by the first attenuating means for attenuating the audio signal regardless of the frequency, and a second attenuating means for attenuating the audio signal in a predetermined frequency band. Including at least one, wherein the attenuation rate of the first attenuation means varies depending on the level of the audio signal. To.
  According to a fourth aspect of the present invention, there is provided an audio recording apparatus for recording an audio signal with an optical pickup in a plurality of empty areas discretely formed on a disk recording medium, wherein the microphone continuously captures an audio signal from the outside, A writing means for temporarily writing the audio signal captured by the microphone into the buffer; and a moving means for moving the optical pickup for recording the audio signal stored in the buffer in each empty area. Attenuating means for attenuating the audio signal when the optical pickup is moved by the first attenuating means for attenuating the audio signal regardless of the frequency, and a second attenuating means for attenuating the audio signal in a predetermined frequency band. The frequency band that includes at least one and is attenuated by the second attenuation means depends on the level of the audio signal. Characterized in that it comprises.
  An audio recording apparatus according to the invention of claim 5 is a microphone for continuously recording audio signals from the outside in an audio recording apparatus for recording audio signals by an optical pickup in a plurality of empty areas discretely formed on a disk recording medium, A writing means for temporarily writing the audio signal captured by the microphone into the buffer; and a moving means for moving the optical pickup for recording the audio signal stored in the buffer in each empty area. Attenuating means for attenuating the audio signal when the optical pickup is moved by the first attenuating means for attenuating the audio signal regardless of the frequency, and a second attenuating means for attenuating the audio signal in a predetermined frequency band. The determination means includes at least one, and the level of the audio signal is compared with the first threshold every predetermined period. Comparison means, and the first threshold level of the audio signal is continuously It includes a measuring means for measuring a level reduction time which is as follows, and the attenuation means attenuates the audio signal when the level reduction time exceeds a second threshold value.
  An audio recording apparatus according to the invention of claim 6 is a sound recording apparatus for recording an audio signal by an optical pickup in a plurality of empty areas discretely formed on a disk recording medium, and a microphone that continuously takes in an audio signal from the outside, A writing means for temporarily writing the audio signal captured by the microphone into the buffer; and a moving means for moving the optical pickup for recording the audio signal stored in the buffer in each empty area. Attenuating means for attenuating the audio signal when the optical pickup is moved by the first attenuating means for attenuating the audio signal regardless of the frequency, and a second attenuating means for attenuating the audio signal in a predetermined frequency band. Including at least one, the determining means repeatedly calculates the average level of the audio signal for a predetermined period, Decay means is characterized in that for attenuating the audio signal when the average level is equal to or less than the third threshold value.
[0020]
[Action]
In the present invention, the signal level of the portion including the seek noise of the audio signal recorded on the disk recording medium is attenuated. In other words, the microphone continuously captures the audio signal from the outside, and the writing means temporarily writes the audio signal captured by the microphone into the buffer. The moving means moves the optical pickup in order to record the audio signal stored in the buffer in each empty area, and the attenuating means attenuates the signal level of the audio signal when the optical pickup moves by the moving means. Therefore, the audio signal is attenuated when the optical pickup moves.
[0021]
In the preferred embodiment of the present invention, it is determined whether to attenuate the audio signal based on the movement of the optical pickup and the level of the audio signal. That is, the discrimination means discriminates the level of the audio signal captured by the microphone, and the attenuation means attenuates the audio signal according to the discrimination result of the discrimination means.
[0022]
In another preferred embodiment of the invention, the signal level of the audio signal is attenuated by either the first or second method. That is, the first attenuation means attenuates the signal level of the audio signal regardless of the frequency of the audio signal as the first method, and the second attenuation means attenuates only a predetermined frequency band of the audio signal as the second method. .
[0023]
The attenuation rate by the first attenuation means may be changed according to the signal level of the audio signal. Furthermore, it is desirable that the predetermined frequency band includes a frequency band of noise generated due to the movement of the optical pickup, and the frequency band to be attenuated is desirably changed according to the signal level of the audio signal.
[0024]
In another aspect of the present invention, it is determined whether or not to attenuate the signal level of the audio signal based on the signal of a predetermined period acquired from the audio signal. That is, the comparison means compares the signal level of the audio signal with the first threshold value off the predetermined period, and the measurement means measures the level decrease time during which the signal level of the audio signal is continuously below the first threshold value. The attenuation means attenuates the audio signal when the level reduction time of the audio signal exceeds the second threshold.
[0025]
In yet another aspect of the present invention, it is determined whether to attenuate the signal level of the audio signal based on the average level of the signal for a predetermined period obtained from the audio signal. That is, the average level for a predetermined period of the discrimination means audio signal is repeatedly calculated, and the attenuation means attenuates the audio signal when the average level becomes equal to or less than the third threshold value.
[0026]
【The invention's effect】
According to the present invention, the signal level of the audio signal during the seek operation is attenuated and recorded on the disk recording medium. Therefore, the influence of seek noise on the audio signal recorded on the disk recording medium can be reduced.
[0027]
The above object, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.
[0028]
【Example】
[Example 1]
Referring to FIG. 1, in this embodiment, a digital camera 10 constitutes an audio recording device. The digital camera 10 includes a focus lens 12 and a microphone 30. The light image of the subject passing through the focus lens 12 is incident on the light receiving surface of the CCD imager 14. On the light receiving surface, a camera signal (video signal) corresponding to the incident light image is generated by photoelectric conversion.
[0029]
The timing generator (TG) 24 repeatedly reads camera signals from the CCD imager 14 at a predetermined frame rate when a processing command is given from the system controller 26. The read camera signal is converted into a digital signal by the A / D converter 18 through known noise removal and level adjustment in the CDS / AGC circuit 16.
[0030]
On the other hand, the audio signal processing circuit 32 acquires an audio signal from the microphone 30 when a processing command is given from the system controller 26. The acquired audio signal is converted into a digital signal by the A / D converter 34 through predetermined signal processing described later.
[0031]
Specifically, the audio signal circuit 32 is configured as shown in FIG. The audio signal output from the microphone 30 is supplied to the switch 70 directly and through the amplifier 68 through known signal processing by the signal processing circuit 66. The switch 70 is supplied with a signal (hereinafter referred to as “normal signal”) from a signal processing circuit 66 or a signal (hereinafter referred to as “hereinafter referred to as“ normal signal ”) from a signal processing circuit 66 in accordance with a control signal provided from a microcomputer (Digital Signal Processor) 56 described later. The correction signal is called “corrected signal” and output to the A / D converter 34. The amplifier 68 amplifies the audio signal given from the signal processing circuit 66 by a factor k and outputs the amplified signal. Here, the coefficient k is a value smaller than 1, preferably a value in the range of 1/2 to 1/10. Therefore, the amplifier 68 functions as an attenuator.
[0032]
The recording signals converted into digital signals by the A / D converter 18 and the A / D converter 34 are respectively input to the recording signal creation circuit 20. The input camera signal and audio signal (hereinafter referred to as “recording signal”) are output to the buffer memory 22 as a recording signal subjected to predetermined signal processing. The recording signal stored in the buffer memory 22 is appropriately read out by a microcomputer (Digital Signal Processor) 56 that controls the disk drive system.
[0033]
The system controller 26 receives a shutter signal from the shutter button 28b and gives a processing command to the timing generator (TG) 24 and the audio signal processing circuit 32. The shutter signal is also given to the microcomputer 56 by the system controller 26.
[0034]
The disk drive system includes an optical pickup 42. The optical pickup 42 includes an optical lens (objective lens) 50, and the objective lens 50 is supported by an actuator 44. The actuator 44 includes a tracking actuator and a focus actuator. The laser light output from the laser diode 46 is converged by the objective lens 50 and irradiated onto the recording surface of a magneto-optical disk (MO disk) 36 such as an ASMO (Advanced Storage Magneto Optical) disk. As a result, a desired signal is recorded on the recording surface of the magneto-optical disk 36, and the desired signal is read from the recording surface.
[0035]
The magneto-optical disk 36 is a disk that can be recorded on a land track and a groove track. The optical pickup 42 is connected to the sled motor 38 by, for example, a rack and pinion state 40, and its position is moved in the radial direction (outer peripheral direction and inner peripheral direction) of the magneto-optical disk 36 (seek operation).
[0036]
The reflected light of the laser beam reflected by the recording surface of the magneto-optical disk 36 passes through the same objective lens 50 and is irradiated to the photodetector 48. The output of the photodetector 48 is input to an FE signal detection circuit 52 and a TE signal detection circuit 54. The FE signal detection circuit 52 has a focus error signal (FE signal), and the TE signal detection circuit 54 has a tracking error signal (TE signal). Are detected respectively. The detected FE signal and TE signal are respectively supplied to a core (not shown) of the microcomputer 56 via an A / D converter (not shown) provided in the microcomputer 56.
[0037]
Specifically, the photodetector 48 is configured as shown in FIG. The photodetector 48 has four regions A to D provided in the center and regions F and E and regions G and H provided above and below the regions A to H. The regions A to H are respectively detected by the light detecting elements 48a to 48h. It is formed. Laser light emitted from the laser diode 46 is diffracted by a diffraction grating (not shown), and three laser beams 46 a, 46 b and 46 c are irradiated onto the recording surface of the magneto-optical disk 36 through the objective lens 50. That is, as shown in FIG. 17A, with respect to the rotation direction (tangential direction) of the magneto-optical disk 36, the laser beams 46b corresponding to the regions A to D are centered on the regions E and F on the left and right. The corresponding laser beam 46a and the laser beam 46c corresponding to the regions G and H are irradiated. Laser light 46b corresponding to regions A to D is a main beam, and laser light 46a and laser light 46c corresponding to regions E and F and regions G and H are sub-beams. The reproduction signal (recording signal) and the FE signal are extracted from the main beam. The TE signal is extracted from the main beam and the sub beam.
[0038]
The FE signal and the TE signal extracted from the main beam and the sub beam are respectively supplied to the microcomputer 56 as described above. In the microcomputer 56, predetermined processing is performed on the supplied FE signal and TE signal, and a focus actuator control signal is generated from the FE signal, and a tracking actuator control signal and a thread control signal are generated from the TE signal. Each generated control signal is converted into an analog signal by a D / A converter (not shown) included in the microcomputer 56, and a focus actuator control signal, a tracking actuator control signal, and a thread control signal are converted into a focus actuator (FACT) drive circuit 60. , Focus actuator (TACT) drive circuit 62 and sled (SLED) drive circuit 64, respectively.
[0039]
The focus actuator drive circuit 60 adjusts the focus of the objective lens 50 by moving the position of the actuator 44 in the axial direction of the magneto-optical disk 36. The tracking actuator drive circuit 62 moves the position of the actuator 44 in the radial direction (tangential direction) of the magneto-optical disk 36 to cause the objective lens 50 to follow the land track or groove track.
[0040]
Here, the focus actuator control signal is generated based on the FE signal. As described above, the TE leakage signal is included in the FE signal during the seek operation. Due to the TE leakage signal, the amplitude of the FE signal during the seek operation is larger than it should be. Therefore, the focus actuator control signal generated during the seek operation is a signal that causes the optical pickup 42 to focus more than necessary in the axial direction of the magneto-optical disk 36. The optical pickup 42 vibrates greatly due to a focus movement more than necessary during the seek operation, and noise is generated.
[0041]
The sled driving circuit 64 drives the sled motor 38 connected to the optical pickup 42 by the rack and pinion state 40 to move the position of the optical pickup 42 in the radial direction (tangential direction) of the magneto-optical disk 36 (seek). Operation).
[0042]
As described above, during the seek operation of the optical pickup 42, noise is generated due to the vibration of the optical pickup 42 caused by the TE leakage signal included in the FE signal and the operation of the sled mechanism.
[0043]
In the digital camera 10 of this embodiment, the signal level of the audio signal output from the microphone 30 is attenuated, thereby reducing the influence of the noise during the seek operation included in the audio signal on the audio signal that should be recorded.
[0044]
The microcomputer 56 of the digital camera 10 of this embodiment executes the process of the procedure shown in the flowcharts of FIGS. The flowcharts of FIGS. 4 and 5 show processing when recording signals are recorded on the magneto-optical disk 36 in the digital camera 10.
[0045]
When a power source (not shown) of the digital camera 10 is turned on, a start signal is given from the system controller 26 to the microcomputer 56. When the microcomputer 56 receives the activation signal, first, the focus actuator (FACT) drive circuit 60 is turned on in step S1, and the tracking actuator (TACT) drive circuit 62 is turned on in step S3.
[0046]
In step S5, it is determined whether the disk drive system is in the recording mode. When the operator of the digital camera 10 sets the mode switching button 28a to the recording mode, a mode switching signal to the recording mode is given from the system controller 26 to the microcomputer 56, and the disk drive system shifts to the recording mode. When the disk drive system shifts to the recording mode, it is determined in step S5 that the recording mode is set.
[0047]
In step S7, a TOC (Table of Contents) is read from the magneto-optical disk 36, and an empty area table as shown in FIG. 13 is created in a DRAM (Dynamic random access memory) 58. This vacant area table corresponds to the vacant areas (1) to (7) of the magneto-optical disk 36 shown in FIG. 16, and holds the head address and recording capacity of each vacant area.
[0048]
When the operator depresses the shutter button 28 b in the recording mode, a shutter signal is given to the microcomputer 56 via the system controller 26. When the shutter signal is given to the microcomputer 56, it is determined in step S9 that the shutter button 28b is in an on state. If it is determined that the shutter button 28b is in the ON state, in step S11, the microcomputer 56 provides a switching control signal to the switch 70 (see FIG. 2A) included in the audio signal processing circuit 32, and the audio signal processing circuit 32. The audio signal output from is set as a normal signal.
[0049]
Next, in step S13, the microcomputer 56 determines whether or not the buffer memory 22 is empty, that is, whether or not data to be recorded (hereinafter referred to as “recording data”) still exists in the buffer memory 22. The absence of data in the buffer memory 22 is a data recording end condition. If it is determined that there is data (recording data) to be recorded in the buffer memory 22, a free area for recording data is determined based on the free area table (see FIG. 13) recorded in the DRAM 58 in step S17. As a method of determining the free area, a method of selecting from a free area having a large free capacity can be considered.
[0050]
In step S19, it is determined whether the amount of data stored in the buffer memory 22 is equal to or less than a predetermined threshold value. Here, the predetermined threshold value is determined so that data overflow or depletion of the buffer memory 22 does not occur, for example, based on a data storage speed in the buffer memory 22, a capacity of a free area for recording data, a writing speed, and the like. Value.
[0051]
If it is determined that the amount of data stored in the buffer memory 22 is greater than or equal to the threshold value, the tracking actuator drive circuit 62 is turned off in step S23. In step S25, the sled driving circuit 64 is turned on, and the optical pickup 42 is threaded toward the track in which the empty area (determined in step S17) exists (seek operation).
[0052]
In step S27, the microcomputer 56 provides the switching control signal to the switch 70 of the audio signal processing circuit 32, and the audio signal output from the audio signal processing circuit 32 is attenuated by a factor k times by the amplifier 68 (hereinafter, referred to as the audio signal). , Referred to as “correction signal”). Therefore, the audio signal processing circuit 32 outputs an audio signal whose signal level is attenuated.
[0053]
In step S29, it is determined whether or not the optical pickup 42 has reached the target track. If it is determined that it has reached, the sled (SLED) drive circuit 64 is turned off in step S31 to end the seek operation, and the tracking actuator drive circuit 62 is turned on in step S33.
[0054]
Further, in step S35, the microcomputer 56 gives a switching control signal to the switch 70 of the audio signal processing circuit 32, and the signal output from the audio signal processing circuit 32 is used as the audio signal (hereinafter referred to as "normal signal" ”).
[0055]
In step S37, the microcomputer 56 acquires a recording signal corresponding to the free capacity of the recording area (determined in step S17) from the buffer memory 22, and records it in the free area. When the recording in the free area is completed, the free area table (see FIG. 13) recorded in the DRAM 58 is updated in step S39.
[0056]
When the update of the free area table is completed, the process returns to step S13 to determine again whether or not the buffer memory 22 is empty. When recording data remains in the buffer memory 22, a free area is determined again in step S17, and the processing from step S19 to step S37 is repeated to record the remaining recording data.
[0057]
If it is determined in step S19 that the amount of recording data stored in the buffer memory 22 is less than the threshold value, it is determined in step S21 whether the shutter button 28b is in an off state. When the shutter button 28b is in the on state, the process returns to step S19 to determine again whether or not the amount of recording data is greater than or equal to the threshold value. On the other hand, when the shutter button 28b is in the OFF state, no record data is accumulated in the buffer memory 22 any more, so the process proceeds to step S23 and subsequent steps, and the record data remaining in the buffer memory 22 is written.
[0058]
When the recording data is recorded, it is determined in step S13 that the buffer memory 22 is empty, and the TOC of the magneto-optical disk 36 is updated based on the empty area table recorded in the DRAM 58 in step S15. Returning to the step, the data recording process is terminated.
[0059]
In the digital camera 10 of this embodiment, the signal level of the audio signal is attenuated during the seek operation for recording the recording signal on the magneto-optical disk 36, so that the signal level of the portion including noise during the seek operation of the audio signal is lowered. . Therefore, the seek noise included in the audio signal recorded on the magneto-optical disk 36 becomes inconspicuous.
[0060]
[Example 2]
In the digital camera 10 according to the second embodiment, not only the signal level of the audio signal is lowered during the seek operation, but also the frequency band other than the frequency band including many seek noise frequencies in the frequency band of the audio signal using the filter circuit. Only pass through.
[0061]
The configuration of the digital camera 10 of the second embodiment is different from the digital camera 10 of the first embodiment (FIG. 1) only in the configuration of the audio signal processing circuit 32, and the other configurations and operations are the same. Only the configuration of the circuit 32 will be described.
[0062]
Specifically, the audio signal processing circuit 32 is configured as shown in FIG. The audio signal output from the microphone 30 is given to the amplifier 68 and the switch 70 through known signal processing by the signal processing circuit 66, respectively. The amplifier 68 amplifies the given audio signal by a factor k and supplies it to the filter circuit 72. Here, the value of the coefficient k is 1 or less. Therefore, the amplifier 68 functions as an attenuator. When the value of the coefficient k is 1, the correction signal is a signal in which only the filter effect by the filter circuit 72 is added to the audio signal output from the microphone 30.
[0063]
The filter circuit 72 is a low-pass filter (LPF), passes only frequencies below the frequency band including many seek noise frequencies, and applies the same to the switch 70. The frequency of the seek noise is 6 kHz to 7 kHz, and the filter circuit (LPF) 70 preferably passes only the frequency band of 2 kHz or less.
[0064]
In the digital camera 10 of this embodiment, the signal level of the audio signal is attenuated and the frequency band of seek noise is cut during the seek operation for recording the recording signal on the magneto-optical disk 36. Therefore, the seek noise included in the audio signal recorded on the magneto-optical disk 36 becomes less noticeable.
[0065]
The filter circuit 70 is not limited to a low-pass filter, and may be configured by a band rejection filter (BEF). At this time, the filter circuit 70 cuts the frequency band of 6 kHz to 7 kHz.
[0066]
[Example 3]
The noise included in the audio signal becomes more prominent when the level of the audio signal to be originally recorded is low. Therefore, in the digital camera 10 according to the third embodiment, the audio signal output from the audio signal processing circuit 32 is switched to the correction signal only during the seek operation and when the audio signal level is low. Note that the time when the level of the audio signal is low refers to the time when the level of the audio signal is lower than a predetermined threshold by a certain period (time interval “T”).
[0067]
The configuration of the digital camera 10 of the third embodiment is the same as the configuration of the digital camera 10 of the second embodiment except for the configuration of the audio signal processing circuit 32. Specifically, the audio signal processing circuit 32 is configured as shown in FIG. The audio signal processing circuit 32 of FIG. 3A is different from the audio signal processing circuit 32 of the second embodiment (FIG. 2B) in that the output of the audio signal processing circuit 66 is given to the microcomputer 56 (audio signal processing). The circuit 32 includes an amplifier 68 and a filter circuit 72. The function of the filter circuit 72 is LPF or BEF). Based on the audio signal obtained from the signal processing circuit 66, the microcomputer 56 determines switching of the output of the audio signal processing circuit 32 (normal signal and correction signal), and gives the determination result to the switch 70.
[0068]
The microcomputer 56 in the digital camera 10 according to the third embodiment executes the processing shown in the flowcharts of FIGS. 6 and 7 are processes related to recording of recording signals of the disk drive system (hereinafter referred to as “main routine”), and the flowchart of FIG. 8 is output from the audio signal processing circuit 32. This is processing related to determination of switching of audio signals (hereinafter referred to as “switching determination routine”). The main routine (FIGS. 6 and 7) and the switching determination routine (FIG. 8) are executed independently and in parallel by the microcomputer 56.
[0069]
The processing of the main routine shown in FIGS. 6 and 7 is the same as that shown in FIGS. 4 and 4 of the first embodiment except that a determination part (step S71 in FIG. 6) for switching the audio signal output from the audio signal circuit 32 is added. The processing is almost the same as that shown in FIG. Therefore, the switching determination routine in FIG. 8 will be mainly described.
[0070]
First, the microcomputer 56 turns off the switching flag in step S101, and turns off the timer flag in step S103. Here, the switching flag is a flag for holding a determination result as to whether or not the output of the audio signal circuit 32 is switched from the normal signal to the correction signal. The timer flag is a flag for holding a state indicating whether or not a timer for counting a time during which the output of the signal processing circuit 66 satisfies a predetermined condition is started.
[0071]
Next, the microcomputer 56 acquires an audio signal (hereinafter referred to as “unit signal”) corresponding to the time ΔT from the signal processing circuit 66 in step S105, and determines whether or not the signal level of the acquired unit signal is equal to or less than a threshold value. Determination is made in step S107. Here, the threshold value is, for example, a value of about one-tenth of the maximum range of the microphone 30. Hereinafter, this threshold is set to “M₁". The time ΔT is assumed to be a time corresponding to the minimum signal that can be handled by the microcomputer 56.
[0072]
The signal level of the unit signal is M₁If it is higher, it is determined in step S121 whether or not the timer flag is on. At this time, since the timer flag is in the OFF state, the process returns to step S105, and the next unit signal is acquired from the signal processing circuit 66.
[0073]
On the other hand, in step S107, the signal level of the unit signal is M.₁If it is determined as follows, it is determined in step S109 whether or not the timer flag is on. Since the timer flag is currently off, the timer flag is turned on in step S111, and the timer (up counter) is started in step S113 (t in FIGS. 14A and 14B).₁). Although not shown in the flowchart, the microcomputer 56 counts the timer after starting the timer.
[0074]
Next, in step S115, it is determined whether or not the switching flag is on. Since the switching flag is not on, the value indicated by the timer is “T” in step S117._thre”(Threshold) or more. Where the value T_threIs a time as a threshold and is a few seconds of 2-3. The value indicated by the timer is T_threIf it is smaller, the setting of the switching flag in step S119 is skipped, and the process returns to step S105 to acquire the next unit signal again. Then, the acquired unit signal is changed to M in step S107.₁If it is determined that the timer flag is greater than the threshold value, it is determined in step S121 whether or not the timer flag is on. When the timer flag is on, the timer is reset at step S123, and the timer flag is turned off at step S125 (t in FIG. 14A).₂). In step S127, it is determined whether or not the switching flag is on. At this time, since the switching flag is in the off state, the clearing of the switching flag in step S129 is skipped and the process returns to step S105.
[0075]
On the other hand, in step S117, the value indicated by the timer is T._threIf it is determined that the above is true, the switching flag is turned on in step S119 (t in FIG. 14B).₂) Return to step S105. Once the switching flag is turned on, the value of the unit signal newly acquired in step S105 is changed again to the threshold value M in step S107.₁The switching flag remains in the on state until it is determined that it is larger.
[0076]
In step S107, the value of the unit signal is M.₁If it is determined that the timer flag is larger, it is determined in step S121 whether or not the timer flag is on. T in FIG. 14 (B)_ThreeIn step S123, since the timer flag is on, the timer is reset in step S123, and the timer flag is turned off in step S125. Further, in step S127, it is determined whether or not the switching flag is on. Similarly, t in FIG._ThreeIn step S129, since the switching flag is on, the switching flag is turned off in step S129, and the process returns to step S105. In the same manner, in the switching determination routine, the setting of the ON state and the OFF state of the switching flag is repeated according to the signal level of the audio signal output from the signal processing circuit 66.
[0077]
In the processing of the main routine (FIGS. 6 and 7), the output from the audio signal processing circuit 32 is switched based on the determination result (switch flag value) in the switching determination routine. Specifically, when it is determined in step S69 in FIG. 6 that the capacity of the recording signal stored in the buffer memory 22 is equal to or greater than the threshold value, or when it is determined in step S71 that the shutter button 28b is in the off state. In step S73, it is determined whether or not the switching flag is on. If the switching flag is on, in step S75, the microcomputer 56 gives a switching control signal to the switch 70 (see FIG. 3A) included in the audio signal processing circuit 32, and corrects the output of the audio signal processing circuit 32. Switch to signal. On the other hand, if the switching flag is off, the signal switching in step S75 is skipped and the subsequent processing is executed.
[0078]
As described above, in the digital camera 10 according to the third embodiment, the audio signal output from the signal processing circuit 66 is always monitored. Then, it is determined whether or not the level of the audio signal is below a certain level for a certain period of time, and the on / off state of the switching flag is set based on the determination result. The value set in the switching flag thus determined is referred to only during the seek operation. If the switching flag is in the ON state, the value output from the audio signal processing circuit 32 is switched to the correction signal. Therefore, the audio signal is switched to the correction signal only during the seek operation and when the level of the audio signal is low, that is, when the influence of seek noise is strong and the audio signal needs to be corrected.
[0079]
Note that, as described above, the method for determining whether or not to switch the audio signal output from the audio signal processing circuit 32 (conditions for turning on the switching flag) is that the signal level of the audio signal is a predetermined time (T_thre) Over a predetermined threshold (M₁) The determination may be based on various methods, not limited to the following. For example, you may make it determine based on whether the average signal level of the audio | voice signal corresponded to a predetermined time interval (T) is below a predetermined threshold value.
[0080]
At this time, the microcomputer 56 executes a switching determination routine shown in the flowchart of FIG. 9 instead of the switching determination routine shown in the flowchart of FIG. That is, only the processing method for setting the switching flag is different from the above-described embodiment (embodiment 3), and the processes shown in the flowcharts of FIGS. 6 and 7 are common. Therefore, only the switching determination routine for setting the switching flag will be described.
[0081]
First, in step S131 of FIG. 9, the switching flag is turned off and initialized. Next, the microcomputer 56 takes in the audio signal corresponding to the time interval T from the signal processing circuit 66 to the DRAM 58 in step S133, and calculates the average signal level of the audio signal corresponding to the time interval “T” taken in the DRAM 58 in step S135. . The value of the time interval T is the threshold value T_threIt may be the same as the value of. In step S137, it is determined whether the average signal level is equal to or lower than a predetermined threshold. Here, the predetermined threshold is, for example, about 1/20 of the output range of the microphone 30. This threshold is hereinafter referred to as “M₂".
[0082]
Average signal level is threshold M₂If it is determined that the following is true, the switching flag is set to the ON state in step S139. In step S141, an audio signal (unit signal) corresponding to time ΔT is acquired from the signal processing circuit 66, and the process returns to step S135 to calculate the average signal level of the audio signal again. Here, the audio signal used for calculating the average level of the audio signal is an audio signal corresponding to the time interval T including the audio signal of ΔT newly captured in step S141. Therefore, in the second step S135, the average signal level of the audio signal corresponding to time ΔT to time T + ΔT is calculated.
[0083]
On the other hand, in step S137, the average signal level is the threshold value M.₂If it is determined that the value is higher, the switching flag is set to the off state (the switching flag is set to the off state even in the off state) in step S143, and the audio signal (unit signal) corresponding to the time ΔT is acquired in step S141. Then, returning to step S137, the average signal level of the audio signal is calculated again.
[0084]
As described above, in the switching determination routine shown in the flowchart of FIG. 9, the average signal level of the audio signal corresponding to the time interval T updated by ΔT is sequentially calculated, and the calculation result is M₂The audio signal switching flag is set to the on state when
[0085]
In the main routine shown in the flowcharts of FIGS. 6 and 7, the value set in the switching flag in step S73 of FIG. 6 is referred only to the seek operation (thread operation). When the switch flag is on, the audio signal output from the audio signal processing circuit 32 is switched to the correction signal in step S75. When the sled driving circuit is turned off in step S83 and the seek operation is completed, the audio signal is switched to the normal signal in step S85.
[0086]
In this way, in the digital camera 10 that executes the switching determination routine shown in the flowchart of FIG. 9, the switching between the normal signal and the correction signal is determined based on the average of the signal level, so the switching determination shown in the flowchart of FIG. The output of the audio signal can be switched more stably and appropriately than the digital camera 10 that executes the routine. A weighted average may be used as a method for calculating the average of the signal level.
[0087]
As described above, in the digital camera 10 according to the third embodiment, the audio signal output from the microphone 30 is constantly monitored, and the average signal level of the audio signal during a seek operation and for a certain period is lower than a predetermined threshold. Only the signal level of the recorded audio signal is attenuated and the frequency band corresponding to the frequency of the seek noise is cut. Therefore, since the audio signal is corrected only when the audio signal level is low and the influence of seek noise is large, there is no possibility that information included in the audio signal is removed more than necessary.
[0088]
Although the above-described audio signal processing circuit 32 in the third embodiment is configured to include both the amplifier 68 and the filter circuit 72, the audio signal processing circuit 32 is configured to include either the amplifier 68 or the filter circuit 72. Also good. Further, the filter circuit 72 may be constituted by either a low-pass filter or a band rejection filter.
[0089]
[Example 4]
The digital camera 10 according to the fourth embodiment changes the degree of correction of the audio signal according to the signal level of the audio signal output from the microphone 30. The digital camera 10 of the fourth embodiment is different from the digital camera 10 of the third embodiment only in the configuration of the audio signal processing circuit 32. Other configurations are the same as those of the digital camera 10 of the third embodiment. The audio signal processing circuit 32 of the fourth embodiment is specifically configured as shown in FIG. In the audio signal processing circuit 32 of this embodiment, as shown in FIG. 3B, not only the switch 70 but also the amplifier 68 and the filter circuit 72 are controlled by control signals from the microcomputer 56. The microcomputer 56 changes the attenuation factor (value of coefficient k) of the amplifier 68 and the cutoff frequency of the filter circuit 72 (LPF) based on the output level (audio signal level) of the signal processing circuit 66. The other points are the same as those of the digital camera 10 of the third embodiment.
[0090]
The microcomputer 56 in the digital camera 10 according to the fourth embodiment executes the processing shown in the flowcharts of FIGS. The flowcharts of FIGS. 10 and 11 show processing (main routine) relating to recording of recording signals of the disk drive system. The flowchart of FIG. 12 is a process (switching determination routine) relating to determination of switching of the audio signal output from the audio signal processing circuit 32. The main routine (FIGS. 10 and 11) and the switching determination routine (FIG. 12) are executed independently and in parallel by the microcomputer 56.
[0091]
When the main routine (FIGS. 10 and 11) determines that the switching flag is on, the values of the cutoff frequency (fc) and attenuation rate (k) set in the switching determination routine are amplified. 68 and the processing of the main routine shown in the flowcharts of FIGS. Therefore, the switching determination routine of FIG. 12 will be mainly described.
[0092]
First, in step S201, the switching flag is turned off and initialized. Next, the microcomputer 56 obtains an audio signal corresponding to the time interval T from the signal processing circuit 66 (see FIG. 3B) in step S203 and loads it into the DRAM 58, and corresponds to the time interval T captured in the DRAM 58 in step S205. The average signal level of the audio signal is calculated. The value of the average signal level calculated at this time is expressed as “Aave”. In step S207, it is determined whether the average signal level is equal to or lower than a predetermined threshold value. Here, the predetermined threshold value is the same value as in the third embodiment.₂And
[0093]
Average signal level is threshold M₂If it is determined as follows, the value of the attenuation factor k (coefficient k) of the amplifier 68 is determined in step S209. The value of the coefficient k is determined based on a predetermined rule as shown in FIG. As shown in FIG. 15A, the value of the coefficient k is given by the function of the average value Aave of the signal level calculated in step S205. As shown in FIG. 15A, the value of the coefficient k gradually increases as the value of Aave increases, and when the value of Aave exceeds a certain value, the value of the coefficient k becomes a constant value “1”. Therefore, the attenuation rate decreases as the value of Aave increases. In the graph of FIG. 15A, the value of the coefficient k is “0” or more, but may include “0”. Further, although the function shown in FIG. 15A changes linearly, it may be a function that changes curvedly, and is preferably determined in accordance with the characteristics of the signal processing system of the digital camera 10.
[0094]
Next, in step S211, the value of the cutoff frequency (fc) of the filter circuit (LPF) 72 is determined. The value of the cut-off frequency (fc) is also determined based on a predetermined rule as shown in FIG. As shown in FIG. 15B, the value of the cutoff frequency (fc) is given by a function of the average value Aave of the signal level calculated in step S205. As shown in FIG. 15B, the cutoff frequency (fc) is a value in the range of the frequency “fL” to the frequency “fH”, and the value of the cutoff frequency gradually increases as the value of Aave increases. To do. However, when the value of Aave becomes equal to or greater than a certain value, the value of the cutoff frequency becomes a certain value “fH”. The function shown in FIG. 15B is a function that varies linearly, but the function for determining the cutoff frequency may be a curved one, and is matched to the characteristics of the signal processing system of the digital camera 10. It is desirable to decide.
[0095]
When the value of the coefficient k and the value of the cutoff frequency are determined, the switching flag is set to the on state in step S213.
[0096]
In step S215, the microcomputer 56 acquires an audio signal (unit signal) corresponding to the time ΔT from the signal processing circuit 66, and returns to step S205. In step S205, the average signal level of the audio signal corresponding to the time interval T is calculated again. Here, the audio signal used for calculating the average signal level Aave is an audio signal corresponding to the time interval T including the audio signal of ΔT newly captured in step S215. Accordingly, in the second step S205, the value of the average signal level Aave is calculated based on the audio signal corresponding to time ΔT to time T + ΔT.
[0097]
On the other hand, in step S207, the value of the average signal level Aave is the threshold value M.₂If it is determined that the value is higher, the switching flag is set to an off state (the switching flag is also set to an off state even in the off state) in step S217, and an audio signal (unit signal) corresponding to time ΔT is acquired in step S215. Then, returning to step S205, the average signal level of the audio signal is calculated again.
[0098]
As described above, the “switching determination routine” of the fourth embodiment constantly monitors the audio signal output from the microphone 30 and calculates the average signal level Aave from the audio signal corresponding to the time interval T. The output switching of the audio signal processing circuit 32 is determined according to the average signal level, and the attenuation rate k (coefficient k) of the amplifier 68 and the cutoff frequency of the filter circuit (LPF) 72 are determined according to the average signal level Aave value. Determine the value of (fc).
[0099]
Then, in the processing of the main routine shown in FIGS. 10 and 11, it is determined in step S173 in FIG. 11 whether or not the switching flag is on. When the switching flag is in the ON state, the microcomputer 56 gives a control signal to the amplifier 68 in step S175, and sets the attenuation rate to be k times the coefficient determined in the “switching determination routine”. Further, the microcomputer 56 gives a control signal to the filter circuit 72 in step S177, and sets the cutoff frequency to be (fc) determined by the “switching determination routine”.
[0100]
When the setting of the attenuation factor of the amplifier 68 and the setting of the cutoff frequency of the filter circuit 72 are completed, the microcomputer 56 supplies a switching control signal to the switch 70 in step S179 to switch the output of the audio signal processing circuit 32 to the correction signal.
[0101]
When the thread control is turned off in step S187 and the seek operation (thread operation) is completed, the microcomputer 56 supplies a control signal to the switch 70 in step S189 to switch the output of the audio signal processing circuit 32 to the normal signal.
[0102]
As described above, in the fourth embodiment, the average signal level Aave of the audio signal obtained from the microphone 30 is calculated, and according to the calculation result, the state of the switching flag, the value of the attenuation factor k (coefficient k) of the amplifier 68, and the filter circuit The value of the cutoff frequency (fc) of (LPF) 72 is determined. When the seek operation is performed, the switching flag is referred to. When the state of the switching flag indicates switching of the output of the audio signal processing circuit 32, the value of the attenuation factor (coefficient k) of the amplifier 68 and the filter circuit (LPF) 72 Change the value.
[0103]
Therefore, according to the digital camera 10 of the fourth embodiment, the audio signal output from the audio signal processing circuit 32 is switched to the correction signal only when the signal level of the audio signal decreases and the influence of seek noise increases. Not only can the information contained in the signal be deleted more than necessary, but also a more appropriate correction signal can be generated.
[0104]
Although the above-described audio signal processing circuit 32 in the fourth embodiment includes both the amplifier 68 and the filter circuit 72, the audio signal processing circuit 32 includes either the amplifier 68 or the filter circuit 72. In this case, the microcomputer 56 controls either the attenuation rate of the amplifier 68 or the cutoff frequency of the filter circuit 72. Further, the filter circuit 72 may be constituted by either a low-pass filter or a band rejection filter.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an overall configuration of an embodiment of the present invention.
2 is a glock diagram showing an example of an internal configuration of an audio signal processing circuit in FIG. 1. FIG.
3 is a block diagram showing another example of the internal configuration of the audio signal processing circuit in FIG. 1. FIG.
FIG. 4 is a flowchart showing a part of processing in the first and second embodiments of the microcomputer shown in FIG. 1;
FIG. 5 is a flowchart showing another part of the processing in the first and second embodiments of the microcomputer shown in FIG. 1;
6 is a flowchart showing a part of processing in the third embodiment of the microcomputer shown in FIG. 1; FIG.
FIG. 7 is a flowchart showing another part of the processing in the third embodiment of the microcomputer shown in FIG. 1;
FIG. 8 is a flowchart showing another part of the processing in the third embodiment of the microcomputer shown in FIG. 1;
FIG. 9 is a flowchart showing another part of the processing in the third embodiment of the microcomputer shown in FIG. 1;
FIG. 10 is a flowchart showing a part of processing in the fourth embodiment of the microcomputer shown in FIG. 1;
FIG. 11 is a flowchart showing still another part of the processing in the fourth embodiment of the microcomputer shown in FIG. 1;
FIG. 12 is a flowchart showing another part of the process in the fourth embodiment of the microcomputer shown in FIG. 1;
FIG. 13 is an illustrative view showing one example of a free area table of a magneto-optical disk;
FIG. 14 is an illustrative view showing one example of a method for switching the output of the audio signal processing circuit;
FIG. 15 is an illustrative view showing one example of a method for determining an amplification factor of an amplifier and a cutoff frequency of a filter circuit;
FIG. 16 is an illustrative view showing one example of empty areas discretely distributed on the magneto-optical disk.
FIG. 17 is an illustrative view showing a relationship between a laser beam irradiated on the magneto-optical disk and a photodetector (light receiving element) for detecting the reflected light.
FIG. 18 is an illustrative view showing spots formed on the light receiving element by the main beam in an ideal state.
FIG. 19 is an illustrative view showing spots formed on the light receiving element by the main beam during the seek operation in the embodiment of FIG. 1;
[Explanation of symbols]
10 Digital camera
14 ... CCD imager
22 ... Buffer memory
26 ... System controller
28a ... Mode switching button
28b ... Shutter button
30 ... Mike
32 Audio signal processing circuit
56: Microcomputer
58… DRAM (Dynamic random access memory)
66 Signal processing circuit
68… Amplifier
70: Switch
72 ... Filter circuit (LPF / BEF)

Claims (8)

In an audio recording apparatus for recording an audio signal by an optical pickup in a plurality of empty areas discretely formed on a disk recording medium,
A microphone that continuously captures the audio signal from the outside;
Writing means for temporarily writing the audio signal captured by the microphone into a buffer; and
Moving means for moving the optical pickup to record the audio signal stored in the buffer in each of the empty areas;
The writing means includes attenuation means for attenuating the audio signal when the optical pickup is moved by the moving means;
A discriminator for discriminating the level of the audio signal captured by the microphone;
The attenuation means attenuates the audio signal according to the determination result of the determination means,
The determining means includes a comparing means for comparing the level of the audio signal with a first threshold at predetermined intervals, and a measuring means for measuring a level decrease time during which the level of the audio signal is continuously below the first threshold. Including
The sound recording apparatus according to claim 1, wherein the attenuation means attenuates the sound signal when the level drop time exceeds a second threshold. In an audio recording apparatus for recording an audio signal by an optical pickup in a plurality of empty areas discretely formed on a disk recording medium,
A microphone that continuously captures the audio signal from the outside;
Writing means for temporarily writing the audio signal captured by the microphone into a buffer; and
Moving means for moving the optical pickup to record the audio signal stored in the buffer in each of the empty areas;
The writing means includes attenuation means for attenuating the audio signal when the optical pickup is moved by the moving means;
A discriminator for discriminating the level of the audio signal captured by the microphone;
The attenuation means attenuates the audio signal according to the determination result of the determination means,
The determination means repeatedly calculates an average level of the audio signal for a predetermined period,
The audio recording apparatus according to claim 1, wherein the attenuation means attenuates the audio signal when the average level becomes a third threshold value or less. In an audio recording apparatus for recording an audio signal by an optical pickup in a plurality of empty areas discretely formed on a disk recording medium,
A microphone that continuously captures the audio signal from the outside;
Writing means for temporarily writing the audio signal captured by the microphone into a buffer; and
Moving means for moving the optical pickup to record the audio signal stored in the buffer in each of the empty areas;
The writing means includes attenuation means for attenuating the audio signal when the optical pickup is moved by the moving means;
The attenuation means includes at least one of first attenuation means for attenuating the audio signal regardless of frequency, and second attenuation means for attenuating the audio signal in a predetermined frequency band,
The audio recording apparatus according to claim 1, wherein the attenuation rate of the first attenuation means varies depending on the level of the audio signal. In an audio recording apparatus for recording an audio signal by an optical pickup in a plurality of empty areas discretely formed on a disk recording medium,
A microphone that continuously captures the audio signal from the outside;
Writing means for temporarily writing the audio signal captured by the microphone into a buffer; and
Moving means for moving the optical pickup to record the audio signal stored in the buffer in each of the empty areas;
The writing means includes attenuation means for attenuating the audio signal when the optical pickup is moved by the moving means;
The attenuation means includes at least one of first attenuation means for attenuating the audio signal regardless of frequency, and second attenuation means for attenuating the audio signal in a predetermined frequency band,
The audio recording apparatus according to claim 1, wherein the frequency band to be attenuated by the second attenuating unit varies depending on the level of the audio signal. In an audio recording apparatus for recording an audio signal by an optical pickup in a plurality of empty areas discretely formed on a disk recording medium,
A microphone that continuously captures the audio signal from the outside;
Writing means for temporarily writing the audio signal captured by the microphone into a buffer; and
Moving means for moving the optical pickup to record the audio signal stored in the buffer in each of the empty areas;
The writing means includes attenuation means for attenuating the audio signal when the optical pickup is moved by the moving means;
The attenuation means includes at least one of first attenuation means for attenuating the audio signal regardless of frequency, and second attenuation means for attenuating the audio signal in a predetermined frequency band,
The determining means includes a comparing means for comparing the level of the audio signal with a first threshold at predetermined intervals, and a measuring means for measuring a level decrease time during which the level of the audio signal is continuously below the first threshold. Including
The sound recording apparatus according to claim 1, wherein the attenuation means attenuates the sound signal when the level drop time exceeds a second threshold. In an audio recording apparatus for recording an audio signal by an optical pickup in a plurality of empty areas discretely formed on a disk recording medium,
A microphone that continuously captures the audio signal from the outside;
Writing means for temporarily writing the audio signal captured by the microphone into a buffer; and
Moving means for moving the optical pickup to record the audio signal stored in the buffer in each of the empty areas;
The writing means includes attenuation means for attenuating the audio signal when the optical pickup is moved by the moving means;
The attenuation means includes at least one of first attenuation means for attenuating the audio signal regardless of frequency, and second attenuation means for attenuating the audio signal in a predetermined frequency band,
The determination means repeatedly calculates an average level of the audio signal for a predetermined period,
The audio recording apparatus according to claim 1, wherein the attenuation means attenuates the audio signal when the average level becomes a third threshold value or less. A discriminator for discriminating the level of the audio signal captured by the microphone;
7. The audio recording apparatus according to claim 3, wherein the attenuation unit attenuates the audio signal according to a determination result of the determination unit. 8. The audio recording apparatus according to claim 3, wherein the predetermined frequency band includes a frequency band of noise caused by movement of the optical pickup.

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