JPH11232802A - Noise reducing device for electronic equipment and for recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely reduce noise components which are mixed in information signals even at the time of transition of the operation mode of electronic equipment without substitutically lowering the quality of the signals and without being affected by disturbances. SOLUTION: This device is provided with adaptive filters 6 for generating, based on the driving signal from a driving signal source (microcomputer) 15 and noise error components, digital noise correlation signals which consist of the fundamental of a frequency equivalent to that of an energy wave from an energy wave generating means (rotary drum) 11 and its higher harmonics and which have correlations with digital noise components mixed in the information signals based on the energy wave a subtracting means 5 for obtaining output digital information signals in which digital noise components are reduced by subtracting digital noise correlation signals from input digital information signals, and a variable gain means 8 which varies step gains of output information signals from the subtracting means 5 and supply them to the adaptive filters 6 as noise error components.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a noise reduction device for electronic equipment and a noise reduction device for recording devices.

[0002]

2. Description of the Related Art For example, a video camera-integrated video tape recorder has a built-in microphone.
The microphone also picks up noise caused by the rotation of the rotating drum having the rotating magnetic head, so that the sound quality of the audio signal recorded on the magnetic tape together with the video signal is degraded.
The smaller the video camera-integrated video tape recorder, the higher the level of noise picked up by the microphone.

A noise component included in an audio signal from a microphone is composed of a fundamental wave having a frequency equal to the rotation frequency of the rotating drum and second to many harmonics distributed over a wide band within the audio signal band. ing. Therefore, conventionally, an audio signal from a microphone is supplied to a comb filter having a delay line having a delay time equal to the reciprocal of the rotation frequency of the rotating drum, and the fundamental wave and its secondary to
A noise component consisting of a large number of harmonics is reduced.

In such a conventional noise reduction apparatus, a fundamental wave and a sound having a frequency equal to the rotation frequency of the rotating drum included in an audio signal from the microphone are used by using a comb filter having a frequency equal to the rotation frequency of the rotating drum. Since the noise component consisting of the second to many harmonics distributed in a wide band within the signal band was reduced, the comb filter not only reduced the noise component but also the rotation frequency of the rotating drum in the audio signal. Since the audio signal components having the same frequency and an integral multiple of the frequency are also reduced, there is a disadvantage that the sound quality is deteriorated such that the sound is cut or the phase is rotated. Also, in the case of noise reduction for a two-channel audio signal from two microphones, a comb filter is required for two channels.
When noise is reduced by digital processing, 2
D-RA for each channel comb filter
M must be provided.

[0005]

A description will be given of the noise reduction device of the recording device proposed above. The noise reduction device of this recording device has a microphone, a rotating head driven by a motor, and having a rotating head, and a rotating drum around which a magnetic tape is wound and guided. In a noise reduction device of a recording device in which a noise component mixed in an audio signal from a microphone is reduced and the audio signal with the reduced noise component is recorded on a magnetic tape, a motor drive signal from a servo means for the motor is provided. Means for varying a duty factor and a delay amount of a drive pulse based on the following: an equalizing means to which a motor driving pulse is supplied from the variable means; and a motor drum to which a motor driving pulse is supplied from the equalizing means. The rotation of the rotating drum consists of a fundamental wave with a frequency equal to the rotation frequency of An adaptive filter that generates a digital noise correlation signal having a correlation with a digital noise component based on noise picked up by a microphone based on the input signal and a digital noise signal obtained by digitally converting an audio signal from the microphone. Subtraction means for subtracting the correlation signal to obtain an output digital audio signal with a reduced digital noise component, wherein the output digital audio signal from the subtraction means is supplied to the adaptive filter as an error component. It is.

[0006] According to the prior art, the quality of the audio signal is not degraded so much, and is not affected by disturbance.
It is possible to obtain a noise reduction device of a recording device capable of reducing a noise component mixed in an audio signal. A variable means for varying the duty factor and delay amount of the drive pulse and an equalizing means to which the drive pulse is supplied from the variable means are jointly included in the digital audio signal by an adaptive filter having a small number of taps and a small number of processing steps. A digital noise correlation signal sufficiently approximated to the digital noise component is obtained. Further, since a microphone or the like for detecting a sound based on the rotation of the rotating drum is not required, the configuration is simplified. Furthermore, even if the noise component mixed into the audio signal has a variation due to a difference in the model or a change with time, the adaptive filter follows the adaptive filter.
Since a digital noise correlation signal approximating the digital noise component of the noise component can be generated, it is not necessary to make adjustments according to the variation due to the difference in the model of the noise component or the change over time.

In such a noise reduction device of a recording apparatus of the prior art, when a video signal from a video camera and an audio signal from a microphone are being recorded on a magnetic tape, a recording pause or recording standby may occur. The noise picked up by the microphone includes noise due to rotation of the rotating drum and its resonance noise during recording, and noise (slap noise) of the rotating magnetic head contacting the magnetic tape. No noise due to rotation of the rotating drum or noise caused by the rotating magnetic head contacting the magnetic tape during recording standby.

Further, in the noise reduction device of the recording apparatus of the prior art, the amount of noise cancellation subtracted from the microphone also changes according to the magnitude of the noise of each device. During the mode transition between the recording standby modes, the noise cancellation amount cannot follow the change amount of the mechanical noise MN, so that the noise cancellation is not reliably performed. There is a disadvantage that the noise is apt to be heard.

In view of the above, the present invention includes an energy wave generating means driven by a drive signal from a drive signal source to generate an energy wave, and information is generated based on the energy wave from the energy wave generating means. In a noise reduction device for electronic equipment designed to reduce noise components mixed in signals, the noise components mixed in the information signals can be reliably reduced without significantly reducing the quality of the information signals and without being affected by disturbances. It is an object of the present invention to propose a device that can reduce the noise component mixed in the information signal even when the operation mode of the electronic device changes.

Further, the present invention includes a microphone and rotating means driven by a motor, and reduces noise components mixed into an audio signal from the microphone through the microphone based on rotation by the rotating means. In the noise reduction device of the recording device, the noise component mixed into the audio signal can be reliably reduced without significantly lowering the quality of the audio signal and without being affected by disturbance. An object of the present invention is to propose a device capable of surely reducing a noise component mixed in an audio signal even at the time of transition of an operation mode.

[0011]

According to a first aspect of the present invention, there is provided an energy wave generating means for generating an energy wave driven by a driving signal from a driving signal source. In the noise reduction device for an electronic device, the noise component mixed into the information signal is reduced based on the drive signal from the drive signal source and the noise error component. An adaptive filter comprising a fundamental wave having the same frequency and a harmonic thereof and generating a digital noise correlation signal having a correlation with a digital noise component based on the noise component mixed into the information signal based on the energy wave from the energy wave generating means; Digital noise correlation from the input digital information signal obtained by digitally converting the information signal The subtracted No., a subtraction means for obtaining the output digital information signal digital noise components have been reduced,
Variable gain means for changing the step gain of the digital information signal output from the subtraction means and supplying the digital gain as an error noise component to the adaptive filter.

According to the first aspect of the present invention, the fundamental wave having the frequency equal to the frequency of the energy wave from the energy wave generating means and its fundamental wave are generated by the adaptive filter based on the drive signal from the drive signal source and the noise error component. A digital noise correlation signal composed of harmonics and having a correlation with a digital noise component based on a noise component mixed into the information signal is generated based on the energy wave from the energy wave generating means. The subtraction means subtracts the digital noise correlation signal from the input digital information signal obtained by digitally converting the information signal to obtain an output digital information signal with a reduced digital noise component. The variable gain means changes the step gain of the digital information signal output from the subtraction means and supplies the digital information signal to the adaptive filter as an error noise component.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first aspect of the present invention comprises an energy wave generating means which is driven by a driving signal from a driving signal source to generate an energy wave, based on the energy wave from the energy wave generating means. In a noise reduction device for an electronic device configured to reduce a noise component mixed in an information signal, a frequency equal to a frequency of an energy wave from an energy wave generation unit is determined based on a drive signal from a drive signal source and a noise error component. An adaptive filter that generates a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into an information signal, based on the energy wave from the energy wave generating means, comprising: A digital noise correlation signal is subtracted from the input digital information signal obtained by digitally converting the signal. Subtraction means for obtaining an output digital information signal having a reduced digital noise component, and variable gain means for varying the step gain of the output digital information signal from the subtraction means and supplying the digital gain as an error noise component to the adaptive filter Are provided.

According to a second aspect of the present invention, in the noise reduction device for an electronic device according to the first aspect of the present invention, the variable gain means adjusts a step gain near a transition period of an operation mode of the electronic device to a predetermined value near an operation mode. Different from the step gain, the noise canceling pull-in speed near the transition period of the operation mode is set to be higher than the pull-in speed near the operation mode.

According to a third aspect of the present invention, in the noise reduction device for an electronic device according to the first aspect of the present invention, the operation mode of the electronic device is:
It changes between a first operation mode in which the level of the noise component mixed in the information signal is high and a second operation mode in which the level of the noise component mixed in the information signal is low as compared with the first operation mode. In this case, the variable gain means sets the noise canceling pull-in speed in the second operation mode to the first speed.
The step gain near the first operation mode and the step gain near the second operation mode are made different from each other so as to be smaller than the pull-in speed of the noise cancellation in the operation mode.

According to a fourth aspect of the present invention, there is provided an energy wave generating means driven by a drive signal from a drive signal source to generate an energy wave, and an information signal is generated based on the energy wave from the energy wave generating means. In a noise reduction device of an electronic device configured to reduce a mixed noise component, a fundamental wave having a frequency equal to a frequency of an energy wave from an energy wave generation unit is provided based on a drive signal and a noise error component from a drive signal source. An adaptive filter that generates a digital noise correlation signal having a harmonic with the digital noise component based on the noise component mixed into the information signal based on the energy wave from the energy wave generating means, and a digital conversion of the information signal. The digital noise correlation signal is subtracted from the obtained input digital information signal, Subtracting means for obtaining an output digital information signal Jitarunoizu component is reduced, it is provided with a switching means for controlling the supply and non-supply to the subtraction means of the digital noise correlation signal from the adaptive filter.

According to a fifth aspect of the present invention, in the noise reduction device for an electronic device according to the fourth aspect of the present invention, the operation mode of the electronic device includes a first operation mode having a high level of a noise component mixed in the information signal; If the digital signal changes between the first operation mode and the second operation mode in which the level of the noise component mixed into the information signal is low, the digital noise correlation signal is subtracted near the first operation mode. The switching means is controlled so as to be supplied to the means, and the switching means is controlled so that the digital noise correlation signal is not supplied to the subtracting means in the vicinity of the second operation mode.

According to a sixth aspect of the present invention, there is provided an energy wave generating means driven by a drive signal from a drive signal source to generate an energy wave, and an information signal is generated based on the energy wave from the energy wave generating means. In a noise reduction device of an electronic device configured to reduce a mixed noise component, a fundamental wave having a frequency equal to a frequency of an energy wave from an energy wave generation unit is provided based on a drive signal and a noise error component from a drive signal source. An adaptive filter that generates a digital noise correlation signal having a harmonic with the digital noise component based on the noise component mixed into the information signal based on the energy wave from the energy wave generating means, and a digital conversion of the information signal. The digital noise correlation signal is subtracted from the obtained input digital information signal, Subtracting means for obtaining an output digital information signal Jitarunoizu component is reduced, by varying the step gain of the output digital information signal from the subtraction means,
Variable gain means for supplying an adaptive filter as an error noise component and switching means for controlling supply and non-supply of a digital noise correlation signal from the adaptive filter to a subtraction means are provided.

According to a seventh aspect of the present invention, in the noise reduction device for an electronic device according to the sixth aspect, the operation mode of the electronic device is as follows.
It changes between a first operation mode in which the level of the noise component mixed in the information signal is high and a second operation mode in which the level of the noise component mixed in the information signal is low as compared with the first operation mode. In this case, the variable gain means sets the noise canceling pull-in speed in the second operation mode to the first speed.
The step gain near the first operation mode and the step gain near the second operation mode are set to be different from each other so as to be smaller than the noise canceling pull-in speed in the first operation mode. The switching means is controlled so that the digital noise correlation signal is supplied to the subtraction means in the vicinity of the operation mode, and the switching is performed so that the digital noise correlation signal is not supplied to the subtraction means in the vicinity of the second operation mode. The means is controlled.

According to an eighth aspect of the present invention, there is provided a microphone and a rotating means driven by a motor. Based on noise caused by the rotation of the rotating means, a noise component mixed into an audio signal from the microphone is passed through the microphone. In a noise reduction apparatus of a recording apparatus in which recording is performed on a recording medium in a reduced manner, the noise reduction apparatus includes a fundamental wave equal to the rotation frequency of a rotation unit and its harmonics based on a drive signal supplied to a motor and a noise error component. An adaptive filter for generating a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the audio signal based on noise due to rotation of the means, and an input digital audio signal obtained by digitally converting the audio signal The digital noise correlation signal is subtracted from the Subtracting means for obtaining an output digital audio signal, by varying the step gain of the output digital audio signal from the subtraction means, as an error noise component, it is provided with a variable gain means for supplying to the adaptive filter.

According to a ninth aspect of the present invention, in the noise reduction apparatus for a recording apparatus according to the eighth aspect of the present invention, the variable gain means includes a step gain near a transition period between the recording mode and the recording pause mode of the recording apparatus. Different from the predetermined step gain near the recording mode, the pull-in speed of noise cancellation near the transition period between the recording mode and the recording pause mode is set to be larger than the pull-in speed near the recording mode. is there.

According to a tenth aspect of the present invention, in the noise reduction apparatus for a recording apparatus according to the ninth aspect of the present invention, the variable gain means sets the noise canceling pull-in speed in the recording pause mode.
The step gain near the recording mode and the step gain near the recording pause mode are made different from each other so as to be smaller than the noise canceling pull-in speed in the recording mode.

According to an eleventh aspect of the present invention, there is provided a microphone and a rotating means driven by a motor. Based on noise caused by rotation of the rotating means, a noise component mixed into an audio signal from the microphone is passed through the microphone. In a noise reduction apparatus of a recording apparatus in which recording is performed on a recording medium in a reduced manner, the noise reduction apparatus includes a fundamental wave equal to the rotation frequency of a rotation unit and its harmonics based on a drive signal supplied to a motor and a noise error component. An adaptive filter for generating a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the audio signal based on noise due to rotation of the means, and an input digital audio signal obtained by digitally converting the audio signal , The digital noise component is reduced by subtracting the digital noise correlation signal from Subtracting means for obtaining an output digital audio signal, it is provided with a switching means for controlling the supply and non-supply to the subtraction means of the digital noise correlation signal from the adaptive filter.

According to a twelfth aspect of the present invention, in the noise reduction device for a recording apparatus according to the eleventh aspect of the present invention, the operation mode of the recording apparatus includes a recording mode and a recording standby mode in which a noise component is not mixed in the audio signal. In the case of changing between the recording modes, the switching unit is controlled so that the digital noise correlation signal is supplied to the subtracting unit near the recording mode, and the digital noise correlation signal is not supplied to the subtracting unit near the recording standby mode. Thus, the switching means is controlled.

According to a thirteenth aspect of the present invention, there is provided a microphone and a rotating means driven by a motor. Based on noise caused by rotation of the rotating means, a noise component mixed into an audio signal from the microphone is passed through the microphone. In a noise reduction apparatus of a recording apparatus in which recording is performed on a recording medium in a reduced manner, the noise reduction apparatus includes a fundamental wave equal to the rotation frequency of a rotation unit and its harmonics based on a drive signal supplied to a motor and a noise error component. An adaptive filter for generating a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the audio signal based on noise due to rotation of the means, and an input digital audio signal obtained by digitally converting the audio signal , The digital noise component is reduced by subtracting the digital noise correlation signal from Subtracting means for obtaining an output digital audio signal, the step gain of the output digital audio signal from the subtraction means to the variable, as an error noise component,
A variable gain means for supplying to the adaptive filter and a switching means for controlling supply and non-supply of the digital noise correlation signal from the adaptive filter to the subtraction means are provided.

According to a fourteenth aspect of the present invention, in the thirteenth aspect of the noise reduction apparatus for a recording apparatus of the present invention, the operation modes of the recording apparatus are a recording mode and a recording standby mode in which noise is not mixed in the audio signal (or In a recording pause mode in which the level of the noise component mixed into the audio signal is smaller than that in the recording mode, the variable gain means:
The step gain near the recording mode and the recording standby mode (or recording) are set so that the noise canceling pull-in speed in the recording standby mode (or recording pause mode) is smaller than the noise canceling pull-in speed in the recording mode. The step gains in the vicinity of the pause mode are made different from each other, and in the vicinity of the recording mode, the switching unit is controlled so that the digital noise correlation signal is supplied to the subtraction unit, and the recording standby mode (or In the vicinity of the recording pause mode, the switching means is controlled so that the digital noise correlation signal is not supplied to the subtraction means.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1, a noise reduction device for an electronic device and a noise reduction device for a recording device according to the present invention will be described with reference to a video camera-integrated video tape recorder (video). A specific example of an embodiment applied to a camera-integrated VTR will be described in detail.

The left and right audio signals from the left and right microphones ML and MR built in the VTR are amplified by amplifier circuits 1L, 1R and an AGC circuit (automatic gain control circuit) 2, respectively.
L and 2R, and supplied to the A / D converters 2L and 2R to be converted into left and right digital audio signals. Various noises are collected by the left and right microphones ML and MR together with sounds to be collected such as human voices. Here, in particular, noise and resonance noise generated when the rotating drum described later rotates and noise (slap noise) caused by the magnetic tape contacting the rotating drum are transmitted through the outer casing of the VTR and into the space. It is intended to reduce noise components radiated, collected by the left and right microphones ML, MR, and mixed into the left and right audio signals from the left and right microphones ML, MR.

These left and right digital audio signals (digital main left and right input signals) are supplied to left and right noise canceling circuits 4L and 4R formed by a DSP (digital signal processor). These left and right digital audio signals are supplied to subtraction means 5, respectively.
The digital left and right noise correlation signals from each adaptive filter 6 are subtracted, and the left and right digital audio signals with reduced noise components are obtained from the output terminals 10L and 10R.

An on / off switch 7 is inserted between the output side of each adaptive filter 6 and each subtracting means 5 for executing and stopping the noise canceling operation, and its on / off is controlled by a microcomputer 15 described later. Is done.

A magnetic tape guide device comprising a rotating drum 11 as an energy wave generating means provided with a stationary drum (not shown) and a rotating magnetic head 12 is provided. It is guided to be wound around the surface. The rotating drum 11 is driven by, for example, 90
It is rotated at a rotation speed of 00 rpm. A servo is applied to the drum motor 13 by the microcomputer 15.

The digital audio signals output from the output terminals 10L and 10R are recorded together with the digital video signals by the rotating magnetic head 12 on the magnetic tape 14 so as to form an inclined track.

Next, the servo for the drum motor 13 will be described with reference to FIG. The motor 13 includes a phase detector 13P that generates a phase detection pulse (the frequency is, for example, 150 Hz) according to the rotation thereof and a frequency detection pulse having a frequency significantly higher than the phase detection pulse according to the rotation. A generated frequency detector 13F is provided. The motor 13 is supplied with a motor drive pulse of 150 Hz from the motor drive circuit 13D.

In FIG. 2, the function of the microcomputer 15 is illustrated by means 32, 34 and 35 described later.

The phase detection pulse from the phase detector 13P is supplied to the phase comparison means 32, and the reference magnetic phase pulse from the input terminal 31 causes the rotary magnetic head 12 to
The phase of the digital video signal to be recorded on the magnetic tape 14 is compared with that of a pulse having a frequency three times that of the vertical synchronizing signal, and the comparison output (phase error signal) is supplied to the control pulse generator 35.

The frequency detection pulse from the frequency detector 13F is supplied to the speed comparison means 34, and the reference frequency pulse from the input terminal 33 (the digital video signal to be recorded on the magnetic tape 14 by the rotating magnetic head 12). The speed is compared with a frequency pulse (an integer fraction of the frequency of the horizontal synchronizing signal) (frequency comparison), and the comparison output (frequency error signal) is supplied to the control pulse generator 35. Then, the phase-controlled and frequency-controlled drive pulse of 150 Hz from the control pulse generator 35 is driven by the drive circuit 13D.
To the drum motor 13.

150 Hz from the control pulse generator 35
Of the drum noise reference signal is the least mean square (LMS: Le
As well as being supplied to the adaptive filter 6 that performs ast mean square processing, digital left and right audio signals from output terminals 10L and 10R described later are supplied to the adaptive filter 6 as noise error components.

The adaptive filter 6 is composed of a fundamental wave equal to the rotation frequency of the rotating drum 11 and second to many harmonics widely distributed in the band of the audio signal from the microphones ML and MR. Based on the rotation at 11, a digital left and right noise correlation signal having a correlation with a noise component mixed in the audio signal from the microphones ML and MR is generated. This adaptive filter 6
The digital noise correlation signal is supplied to each subtraction means 5 and is subtracted from the digital left and right audio signals from the A / D converters 3L and 3R, and the noise from each subtraction means 5 is reduced. Digital left and right audio signals are output from output terminals 10L and 10R.

The digital left and right audio signals from the output terminals 10L and 10R are respectively passed through a limiter 9 to a variable gain amplifier circuit 8 whose step gain (step gain coefficient) is controlled by a step gain control signal from a microcomputer 15. Provided and amplified. Then, the output of each amplifier circuit 8 is used as a noise error component,
The coefficient is supplied to each adaptive filter 6, and the coefficient of the coefficient multiplying means of the adaptive filter 6 described later is changed.

The limiter 9 allows the audio signal component of the audio signal, which coincides with the frequency of the noise component, to pass a noise component having a smaller level than the level of the audio signal component, and a high level audio signal component. In order to supply the adaptive filter 6 with an accurate noise error signal.

An example of the configuration of the adaptive filter 6 will be described with reference to FIG. The input digital signal from the input terminal T1 is converted into delay means D ₁ , D ₂ ,... Having a delay amount equal to the clock cycle of the sample clock of the input digital signal.
........., is supplied to a series circuit of the D _n, the input digital signal from the input terminal T1, the delay means D _1, D _2,
,..., D _n are output from coefficient multiplying means M ₀ ,
M _1, M _2, ............, it is supplied to the M _n, each sample coefficients _{W 0, W 1, W 2} , ............, W n is multiplied by its respective multiplier output adder means AD The signals are supplied and added, and an output digital signal is output to the output terminal T2. The adaptive filter 6 is a FIR (finite impulse response) digital filter.

As the algorithm by the adaptive filter 6, in addition to the least mean square processing method, the steepest descent method, learning identification method, RLS (Recursive Least Square: recursive least square)
Although there are methods such as the convergence time and the amount of processing calculations are small, the least mean square processing method is most advantageous.

The adaptive filter 6 converts sample coefficients W ₀ , W ₁ , W ₂ ,..., W _n according to the number of taps into a sampling period of a digital audio signal to be processed (for example, 1/32000, 1/441
00, 1/48000 seconds, etc.).

[0044]

W (n) = W (n−1) +2 μE (n−1) ·
x (n-1)

Where W (n) is the coefficient of n samples, W
(N-1) is a coefficient of (n-1) samples, mu is a step size, E (n-1) is an error signal of (n-1) samples, and x (n-1) is (n-1) samples. Is a drum noise reference signal. The step size μ is a parameter for determining the convergence speed and the residual error after convergence.

Most of the noise generated by the rotation of the rotary drum 11 is noise (slap noise) generated by the contact of the magnetic tape with the rotating rotary drum 11. In addition, there are two types of noise caused by the rotation of the rotating drum 11 that travel through the outer casing of the VTR and reach the microphones ML and MR, and those that are radiated to the space and reach the microphones ML and MR.
Therefore, the noise component mixed in the audio signals from the microphones ML and MR is the one in which the original noise component based on the rotation of the rotating drum has changed in amplitude and phase by passing through an unknown transfer function circuit. Can be considered.

Therefore, in order to sufficiently reduce the noise component included in the digital audio signal, it is necessary to perform system identification by estimating an unknown transfer function by a least mean square process using an adaptive filter.

Here, the identification in the adaptive filter is as follows.
It is a problem of estimating the impulse response of the system or estimating the output signal.

Compared with the distance between the periphery of the rotary drum 11 and the microphones ML and MR, the microphone M
If the distance between L and MR is sufficiently short, microphone M
The noise components included in the left and right audio signals from L and MR can be treated as the same,
Even if they cannot be handled as the same, the addition signal of the left and right output digital audio signals from each subtraction means 5 is supplied to the adaptive filter 6 as an error component, so that the left and right output digital audio signals The feedback can be applied so that the noise component of is sufficiently small.

As described above, a digital noise correlation signal is generated from the drive signal for driving the rotating drum 11 and is subtracted from the digital audio signal mixed with the noise component, whereby the frequency is equal to the frequency of the noise component of the audio signal itself. Since almost no frequency components are removed, it is possible to avoid sound quality degradation due to audio shaving or phase rotation. Further, since the noise correlation signal is generated based on the driving pulse based on the driving signal for driving the rotary drum 3, the configuration of the noise reduction device is simplified, and the noise reduction of the means for generating the noise correlation signal is reduced. Since there is no influence on the mounting position, structure, accuracy, and the like with respect to the apparatus, the apparatus can be installed on a different type of apparatus, so that it is highly versatile.

Next, the relationship between the VTR mode in the noise reduction device of FIG. 1 and the step gain (step gain coefficient) control for the variable gain amplifier circuit 8 will be described with reference to FIG. FIG. 4A shows the VTR mode,
Here, the recording mode is first changed to the recording pause mode, and then the recording mode is set again at the end. There are transition periods between the first recording mode and the next recording pause mode, and between the recording pause mode and the last recording mode, respectively.

The noise in the recording mode includes drum noise (noise generated by rotation of the drum and its resonance noise) and head noise (noise generated when the rotating magnetic head comes into contact with the magnetic tape <hitting noise> 〉). The noise during the recording pause consists only of drum noise because the magnetic tape stops and is separated from the rotating magnetic head to mechanically protect the magnetic tape. Therefore, it can be seen that the level of noise (mechanical noise) in the recording mode is larger than the level of noise (mechanical noise) in the recording pause.
In the recording standby mode described later, the magnetic tape is stopped, and furthermore, the magnetic tape is separated from the rotary magnetic head to protect the magnetic tape mechanically, and the rotary magnetic head is stopped. Does not occur.

In the case of FIGS. 4B, 4C and 4D described below,
It is assumed that each switch 7 remains on. In the following description, as the step gain (step gain coefficient) increases, the pull-in speed at the time of noise cancellation increases, and conversely, the step gain (step gain coefficient) increases.
Is smaller, the pull-in speed at the time of noise cancellation becomes smaller.

On the contrary, as the step gain (step gain coefficient) increases, the pull-in speed at the time of noise cancellation decreases, and conversely, as the step gain (step gain coefficient) decreases, the noise canceling speed decreases. May be increased.

FIG. 4B shows a conventional example, in which the step gain SG of each amplifier circuit 8 is fixed to a constant value irrespective of the mode of the VTR, and is included in the output digital left and right audio signals. The change of the noise MN is shown. The level of the mechanical noise MN is a low constant value in the first recording mode, gradually increases in the transition period when the mode shifts to the recording pause mode, and gradually decreases when the mode shifts to the next recording pause, but becomes a low constant value. It takes a considerable amount of time until the transition from recording pause mode to the last recording mode gradually increases again.When the last recording mode is entered, the noise level gradually decreases, but the noise level gradually decreases. It takes a considerable amount of time to become.

In the case of FIG. 4B, the level of the mechanical noise MN follows the change of the mechanical noise sound during the mode transition period with a delay of the pull-in time. The level of the noise cancellation signal (digital noise correlation signal) supplied from the adaptive filter 6 to the subtraction means 5 changes so as to cancel the rise in the level of the mechanical noise MN. Therefore, even when the mode transition period is completed, the mechanical noise MN remains at the start of the recording mode or the recording pause mode. Further, when the mode is shifted from the recording mode to the recording pause mode, the level of the mechanical noise MN after processing is increased while the level of the mechanical noise is reduced, because the mechanical noise canceled during the recording mode disappears. This is because the equilibrium state is broken and the digital noise correlation signal is inverted and added.

FIGS. 4C and 4D show specific examples of the embodiment of the present invention. In the case of FIG. 4C, a transition period from the recording mode to the recording pause mode and a predetermined period from the beginning of the recording pause mode, and a transition period from the recording pause mode to the recording mode and a predetermined period from the beginning of the recording mode. In addition, the step gain (step gain coefficient) SG in the amplifier circuit 8 is made larger than the step gain SG in the recording mode and in the recording pause to increase the following speed of the noise cancel signal, so that the transition period and the subsequent mode are changed. An increase in the level of the mechanical noise MN at the beginning is suppressed. The effect of suppressing the level of the mechanical noise MN in the vicinity of the transition period is such that as the step gain SG in the predetermined period is increased,
growing.

Incidentally, unlike the above, the step gain S
If G is constantly increased, the coefficient updating step of the adaptive filter 6 increases, and the adaptive filter 6 oscillates over the optimum cancellation point, so that the error after convergence increases and the noise cancellation effect decreases.

In the case of FIG. 4D, during the recording pause, since no audio signal is recorded on the magnetic tape, the tracking of the noise cancel signal is stopped, that is, the step gain SG is set to 0, and the noise is reduced to the next recording mode. Hold. When the step gain SG is set to 0, since the step update of the adaptive filter 6 is not performed, the immediately preceding noise is continuously canceled. In this case, during the recording pause, the mechanical noise MN
Is higher than the level of the mechanical noise MN in the recording mode, but since the audio signal from the microphone is not recorded on the magnetic tape, there is no problem even if the level of the mechanical noise MN is high. Therefore, during the recording mode, the level of the mechanical noise MN can always be kept constant in the cancel state.

Next, the VTR mode and the cancel on / off control in the noise reduction apparatus of FIG. 1 will be described with reference to FIG. 5, but before that, the recording standby mode will be described. When audio signals from a microphone are supplied to a speaker for monitoring when the rotating drum is not rotating, a long-time recording standby or a video signal from a video camera without a cassette tape loaded into the VTR can be displayed on the LCD. When a monitor is supplied to a finder or a monitor receiver for monitoring (a demonstration at a store, etc.), since the rotating drum does not rotate, sound is picked up by the microphone without generating mechanical noise. During this recording standby, the subtraction means 5 does not need to subtract the noise cancel signal from the digital left and right audio signals. On the other hand, during recording standby, the microcomputer 15
Therefore, since the drum noise reference (reference) signal is not output, if the noise cancellation is performed in this state, a malfunction occurs. Therefore, it is better to stop the noise cancellation operation.

Therefore, in order to prevent noise cancellation in the recording standby mode, in FIG. 1, a cancel on / off control signal for canceling off from the microcomputer 15 is transmitted to each of the noise cancel circuits 4L and 4R. The on / off switch 7 inserted between the output side of the adaptive filter 6 and each subtraction means 5 may be turned off. As a result, the input digital left and right audio signals from the A / D converters 3L and 3R are output as output digital left and right audio signals, respectively.
L and 10R.

Next, FIG. 5 will be described. FIG.
The TR mode is shown. Here, the recording mode is first set, then the recording standby mode is replaced, and finally the recording mode is set again. There are transition periods between the first recording mode and the next recording standby mode, and between the recording standby mode and the last recording mode.

FIG. 5B shows a conventional example, in which the step gain SG of each variable gain amplifying circuit 8 of the noise canceling circuits 4L and 4R is fixed. Also, a noise canceling circuit 4
Each of the ON / OFF switches 7 of L and 4R is always ON. In the first recording mode, the level of the mechanical noise MN remaining in the output digital left and right audio signals is a low constant value, and in the transition period between the recording mode and the recording standby mode, the mechanical noise MN is reduced. The level gradually decreases, and the mechanical noise MN remains even at the beginning of the recording standby mode, and the level gradually decreases and finally reaches zero. In the transition period between the recording standby mode and the last recording mode, the level of the mechanical noise MN gradually increases, and the level of the mechanical noise MN gradually decreases at the beginning of the recording mode. It becomes a constant value with a low level. Therefore, the mechanical noise MN in the transition period between the recording mode and the recording standby mode is not a problem, but in the transition period between the recording standby mode and the recording mode and at the beginning of the recording mode,
The mechanical noise MN remains and its level becomes higher than the level of the mechanical noise MN in the recording mode, and this residual noise is recorded on the magnetic tape.

FIGS. 5C and 5D show specific examples of the embodiment of the present invention. In the case of FIG. 5C, the step gain SG of each of the variable gain amplifying circuits 8 of the noise canceling circuits 4L and 4R is fixed. And in the first recording mode,
Each on / off switch 7 is turned on, and each on / off switch 7 is turned off in a transition period between the recording mode and the recording standby mode and in the recording standby mode. Then, in the transition period between the recording standby mode and the last recording mode and in the last recording mode period, each on / off switch 7 is turned on. In this case, in the first recording mode, the mechanical noise MN
Is a low constant value, and when entering a transition period between the recording mode and the recording standby mode, at the end of the transition period,
Since the rotation of the rotating drum 11 is stopped, the mechanical noise M
The level of N gradually decreases and finally reaches zero. And
In the recording standby mode, the level of the mechanical noise MN is 0. In the transition period between the recording standby mode and the last recording mode, the rotating drum 11 starts rotating, and the noise cancellation amount cannot follow the change amount of the mechanical noise MN, so that the noise cancellation is not performed reliably. , The noise level gradually increases, and the noise level continues to slightly increase even at the beginning of the recording mode. Thereafter, the noise level gradually decreases and finally reaches a constant value with a low level. Therefore, the noise level is low in the transition period between the first recording mode and the recording standby mode, and there is no problem. However, in the transition period between the recording standby mode and the last recording mode and at the beginning of the recording mode. , The level of the mechanical noise MN becomes higher than the level of the mechanical noise MN in the recording mode,
This mechanical noise MN is recorded on the magnetic tape,
It is not as effective as the conventional example of FIG. 5B.

In the case of FIG. 5D, in the first recording mode, the step gain SG of each variable gain amplifying circuit 8 is set to a constant value, and during the transition period between the recording mode and the recording standby mode and in the recording standby mode, it is set to 0. The transition period between the recording standby mode and the last recording mode and the last recording mode have a constant value. Further, the on / off switches 7 are turned on in the first recording mode, and turned off in the transition period between the recording mode and the recording standby mode and in the recording standby mode.
It is turned on in the transition period between the recording standby mode and the last recording mode and in the last recording mode. Thus, in this case, in the first recording mode, the mechanical noise MN
Is a low constant value, and when entering a transition period between the recording mode and the recording standby mode, the level of the mechanical noise MN gradually decreases and finally reaches zero. In this case, the cancel noise signal in the recording mode is held during the recording standby mode. Then, in the recording standby mode, the level of the mechanical noise MN is 0. In the transition period between the recording standby mode and the last recording mode, the on / off switches 7 are turned on to release the hold of the cancel noise signal. In the recording mode, the level of the mechanical noise MN is equal to the level of the mechanical noise MN. In the recording mode, the noise canceling operation is started from the held canceling noise signal at the time of recording. There is no danger that tracking will not be possible, and the level of the mechanical noise MN is kept at that constant value. Accordingly, the rise of the level of the mechanical noise MN during the transition period from the recording standby mode to the last recording mode becomes small.

In the specific example of FIG. 4D, the step gain SG is set to 0 during the transition period between the first recording mode and the recording pause and the recording pause in a state where the on / off switches 7 are turned on, and other periods are set. In FIG. 5D, the on / off switches 7 are turned off during the transition period between the first recording mode and the recording pause and during the recording pause, and are turned on during the other periods. Similarly, the rise of the level of the mechanical noise MN during the transition period from the recording pause mode to the last recording mode becomes small.

Next, a modification of the specific example of FIG. 1 will be described with reference to FIG. Both noise canceling circuits 4L of FIG.
4R, the outputs of the variable gain amplifying circuits 8 in both the noise canceling circuits 4L and 4R are converted by the adding means 16 so as to be averaged.
The added output is supplied to the common adaptive filter 6 as an error component. And a common adaptive filter 6
The digital correlation signal is supplied to the subtraction means 6 through the on / off switch 7 and the A / D converter 3
The digital left audio signal and the digital right audio signal from L and 3R are respectively subtracted. Other configurations are the same as those in FIG.

In the specific example of FIG. 6, the circuit configuration is simpler than in the specific example of FIG. 1, but on the other hand, there are the following disadvantages. That is, the left and right cancel circuits 4L, 4L
For R, one common adaptive filter 6 is provided, the average value of the left and right noise error components is supplied to the adaptive filter 6, and the noise cancellation signal (noise correlation signal) from one common adaptive filter 5 is provided. ) Are supplied to the respective subtraction means 5 of the left and right cancel circuits 4L and 4R. Therefore, when the noises entering the left and right microphones ML and MR are different, compared with the specific example of FIG. The noise removal effect is low.

The energy wave generating means includes vibration, sound, light,
A rotating body, a vibrating body, a vibrator, a speaker, a light emitting source, an oscillator, and the like that generate energy waves such as electromagnetic waves can be used. As the information signal into which the noise component is mixed by these energy waves, an audio signal, a video signal, and the like can be used.

The electronic apparatus to which the present invention can be applied includes a helical scan recording / reproducing apparatus for recording / reproducing a video signal and an audio signal, a recording / reproducing apparatus, a tape recorder, a disk recording apparatus, and a recording / reproducing apparatus. is there.

[0071]

According to the first aspect of the present invention, there is provided an energy wave generating means driven by a drive signal from a drive signal source to generate an energy wave, and the energy wave is generated based on the energy wave from the energy wave generating means. In a noise reduction device for an electronic device configured to reduce a noise component mixed in an information signal, a frequency equal to a frequency of an energy wave from an energy wave generation unit is determined based on a drive signal from a drive signal source and a noise error component. An adaptive filter that generates a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into an information signal, based on the energy wave from the energy wave generating means, comprising: A digital noise correlation signal is subtracted from the input digital information signal obtained by digitally converting the signal. Subtraction means for obtaining an output digital information signal having a reduced digital noise component, and variable gain means for varying the step gain of the output digital information signal from the subtraction means and supplying the digital gain as an error noise component to the adaptive filter With this, the quality of the information signal is not reduced so much, and without being affected by disturbance,
A noise reduction device for an electronic device capable of reliably reducing a noise component mixed in an information signal and capable of reliably reducing a noise component mixed in an information signal even when the operation mode of the electronic device changes. Can be.

According to the second aspect of the present invention, in the noise reduction device for electronic equipment according to the first aspect of the present invention, the variable gain means
By making the step gain near the transition period of the operation mode of the electronic device different from the predetermined step gain near the operation mode, the pull-in speed of the noise cancellation near the transition period of the operation mode is larger than the pull-in speed near the operation mode. As a result, the noise component mixed in the information signal can be reliably reduced without significantly deteriorating the quality of the information signal and without being affected by disturbance. It is possible to obtain a noise reduction device of an electronic device that can surely reduce a noise component mixed in an information signal even at the time of transition.

According to the third aspect of the present invention, in the noise reduction device for an electronic device according to the first aspect of the present invention, the operation mode of the electronic device is different from the first operation mode in which the level of the noise component mixed in the information signal is high. When the variable gain means changes between the first operation mode and the second operation mode in which the level of the noise component mixed in the information signal is low, the variable gain means performs the noise cancellation in the second operation mode. The step gain near the first operation mode and the step gain near the second operation mode are made different from each other so that the pull-in speed of the first operation mode is smaller than the pull-in speed of the noise cancellation in the first operation mode. In this way, the noise component mixed in the information signal can be reliably reduced without significantly deteriorating the quality of the information signal and without being affected by disturbance. , It is possible to obtain the noise reduction device of an electronic device capable of reliably reducing the contaminating noise component to the operation mode information signal even at the time of transition of the electronic device.

According to the fourth aspect of the present invention, there is provided an energy wave generating means driven by a drive signal from a drive signal source to generate an energy wave, and information is generated based on the energy wave from the energy wave generating means. In a noise reduction device of an electronic device configured to reduce a noise component mixed in a signal, a basic frequency having a frequency equal to a frequency of an energy wave from an energy wave generation unit is determined based on a drive signal from a drive signal source and a noise error component. An adaptive filter that generates a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the information signal, based on the energy wave from the energy wave generating means, comprising an Subtract digital noise correlation signal from input digital information signal obtained by digital conversion Te, and subtracting means for obtaining the output digital information signal digital noise components have been reduced, since there is provided a switching means for controlling the supply and non-supply to the subtraction means of the digital noise correlation signal from the adaptive filter,
The noise component mixed into the information signal can be reliably reduced without significantly deteriorating the quality of the information signal and without being affected by disturbance. It is possible to obtain a noise reduction device for an electronic device that can surely reduce a mixed noise component.

According to the fifth aspect of the present invention, in the noise reduction device for an electronic device according to the fourth aspect of the present invention, the operation mode of the electronic device includes the first operation mode in which the level of the noise component mixed into the information signal is high; If the digital signal changes between the first operation mode and the second operation mode in which the level of the noise component mixed into the information signal is low, the digital noise correlation signal is subtracted near the first operation mode. The switching means is controlled so that the digital noise correlation signal is not supplied to the subtraction means in the vicinity of the second operation mode. The noise component mixed in the information signal can be reliably reduced without significantly reducing the noise, and without being affected by disturbance. In addition, it is possible to obtain a noise reduction device for an electronic device that can reliably reduce a noise component mixed in an information signal.

According to the sixth aspect of the present invention, there is provided an energy wave generating means driven by a driving signal from a driving signal source to generate an energy wave, and information is generated based on the energy wave from the energy wave generating means. In a noise reduction device of an electronic device configured to reduce a noise component mixed in a signal, a basic frequency having a frequency equal to a frequency of an energy wave from an energy wave generation unit is determined based on a drive signal from a drive signal source and a noise error component. An adaptive filter that generates a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the information signal, based on the energy wave from the energy wave generating means, comprising an Subtract digital noise correlation signal from input digital information signal obtained by digital conversion Subtraction means for obtaining an output digital information signal having a reduced digital noise component, and variable gain means for varying the step gain of the output digital information signal from the subtraction means and supplying the digital gain as an error noise component to the adaptive filter. Since switching means for controlling supply and non-supply of the digital noise correlation signal from the adaptive filter to the subtraction means are provided, the quality of the information signal is not significantly reduced, and further, without being affected by disturbance, A noise reduction device for an electronic device capable of reliably reducing a noise component mixed in an information signal and capable of reliably reducing a noise component mixed in an information signal even when the operation mode of the electronic device changes. Can be.

According to the seventh aspect of the present invention, in the noise reduction device for an electronic device according to the sixth aspect of the present invention, the operation mode of the electronic device is the first operation mode in which the level of the noise component mixed in the information signal is high. When the variable gain means changes between the first operation mode and the second operation mode in which the level of the noise component mixed in the information signal is low, the variable gain means performs the noise cancellation in the second operation mode. The step gain near the first operation mode and the step gain near the second operation mode are different from each other so that the pull-in speed of the first operation mode is smaller than the pull-in speed of the noise cancellation in the first operation mode. And controlling the switching means so that the digital noise correlation signal is supplied to the subtracting means in the vicinity of the first operation mode.
In the vicinity of the second operation mode, the switching means is controlled so that the digital noise correlation signal is not supplied to the subtracting means. Therefore, the quality of the information signal is not reduced so much and the influence of the disturbance is obtained. Noise reduction device for an electronic device that can reliably reduce noise components mixed in an information signal, and can surely reduce noise components mixed in an information signal even when the operation mode of the electronic device changes. Can be obtained.

According to the eighth aspect of the present invention, there is provided the microphone and the rotating means driven by the motor, and the noise mixed into the audio signal from the microphone through the microphone based on the noise due to the rotation of the rotating means. In a noise reduction apparatus of a recording apparatus in which a component is reduced and recorded on a recording medium, the noise reduction apparatus comprises a fundamental wave equal to a rotation frequency of a rotation unit and a harmonic thereof based on a drive signal supplied to a motor and a noise error component. ,
An adaptive filter that generates a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the audio signal based on noise due to rotation of the rotation unit, and an input digital audio obtained by digitally converting the audio signal Subtract the digital noise correlation signal from the signal,
Subtraction means for obtaining an output digital audio signal with a reduced digital noise component, and variable gain means for varying the step gain of the output digital audio signal from the subtraction means and supplying it to the adaptive filter as an error noise component are provided. Therefore, it is possible to reliably reduce noise components mixed in the audio signal without significantly lowering the quality of the audio signal and without being affected by disturbances, and at the time of transition of the operation mode of the recording apparatus. It is possible to obtain a noise reduction device of a recording device that can surely reduce a noise component mixed in an audio signal.

According to the ninth aspect of the present invention, in the noise reduction apparatus for a recording apparatus according to the eighth aspect of the present invention, the variable gain means
The step gain near the transition period between the recording mode and the recording pause mode of the recording apparatus is made different from a predetermined step gain near the recording mode, and noise cancellation near the transition period between the recording mode and the recording pause mode is performed. The pull-in speed of the audio signal is set to be higher than the pull-in speed in the vicinity of the recording mode, so that the noise component mixed into the audio signal can be reduced without significantly reducing the quality of the audio signal and without being affected by disturbance. It is possible to obtain a noise reduction device of a recording apparatus that can surely reduce the noise component and can surely reduce a noise component mixed in an audio signal even when the operation mode of the recording apparatus changes.

According to the tenth aspect of the present invention, in the noise reduction apparatus for a recording apparatus according to the ninth aspect, the variable gain means controls the pull-in speed of the noise cancellation in the recording pause mode and the noise canceling speed in the recording mode. The step gain near the recording mode and the step gain near the recording pause mode are made different from each other so as to be smaller than the pull-in speed, so that the quality of the audio signal is not reduced so much, and Unaffected,
A noise reduction device for a recording apparatus capable of reliably reducing a noise component mixed in an audio signal and capable of reliably reducing a noise component mixed in an audio signal even when the operation mode of the recording apparatus changes. Can be.

According to the eleventh aspect of the present invention, the microphone and the rotating means driven by the motor are provided, and the noise mixed into the audio signal from the microphone through the microphone based on the noise due to the rotation of the rotating means. In a noise reduction apparatus of a recording apparatus in which a component is reduced and recorded on a recording medium, the noise reduction apparatus comprises a fundamental wave equal to a rotation frequency of a rotation unit and a harmonic thereof based on a drive signal supplied to a motor and a noise error component. ,
An adaptive filter that generates a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the audio signal based on noise due to rotation of the rotation unit, and an input digital audio obtained by digitally converting the audio signal Subtract the digital noise correlation signal from the signal,
A subtraction unit for obtaining an output digital audio signal with a reduced digital noise component and a switching unit for controlling supply and non-supply of the digital noise correlation signal from the adaptive filter to the subtraction unit are provided. The noise component mixed into the audio signal can be reliably reduced without being reduced so much and without being affected by disturbance, and the noise component mixed into the audio signal during the transition of the operation mode of the recording apparatus can be reduced. It is possible to obtain a noise reduction device of a recording device that can be reliably reduced.

According to the twelfth aspect of the present invention, in the noise reduction apparatus for a recording apparatus according to the eleventh aspect of the present invention, the operation modes of the recording apparatus include a recording mode and a recording standby mode in which noise components are not mixed in the audio signal. In the vicinity of the recording mode, the switching means is controlled so that the digital noise correlation signal is supplied to the subtraction means. In the vicinity of the recording standby mode, the digital noise correlation signal is supplied to the subtraction means. Since the switching means is controlled so as not to be supplied, it is possible to surely reduce noise components mixed in the audio signal without significantly lowering the quality of the audio signal and without being affected by disturbance. While you can
It is possible to obtain a noise reduction device of a recording apparatus that can surely reduce a noise component mixed in an audio signal even when the operation mode of the recording apparatus changes.

According to the thirteenth aspect of the present invention, the microphone and the rotating means driven by the motor are provided, and the noise mixed into the audio signal from the microphone through the microphone based on the noise due to the rotation of the rotating means. In a noise reduction apparatus of a recording apparatus in which a component is reduced and recorded on a recording medium, the noise reduction apparatus comprises a fundamental wave equal to a rotation frequency of a rotation unit and a harmonic thereof based on a drive signal supplied to a motor and a noise error component. ,
An adaptive filter that generates a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the audio signal based on noise due to rotation of the rotation unit, and an input digital audio obtained by digitally converting the audio signal Subtract the digital noise correlation signal from the signal,
Subtraction means for obtaining an output digital audio signal with a reduced digital noise component, variable gain means for varying the step gain of the output digital audio signal from the subtraction means and supplying it as an error noise component to an adaptive filter, Since switching means for controlling the supply and non-supply of the digital noise correlation signal from the filter to the subtraction means are provided, the audio signal is not significantly reduced in quality and is not affected by disturbances. It is possible to obtain a noise reduction device for a recording apparatus that can reliably reduce noise components mixed in audio signals and can surely reduce noise components mixed in audio signals even when the operation mode of the recording apparatus changes. .

According to the fourteenth aspect of the present invention, in the noise reducing apparatus for a recording apparatus according to the thirteenth aspect of the present invention, the operation modes of the recording apparatus include a recording mode and a recording standby mode in which noise is not mixed in the audio signal ( Alternatively, when changing between a recording mode and a recording pause mode in which the level of a noise component mixed in the audio signal is smaller than that in the recording mode, the variable gain means may be configured to reduce noise in the recording standby mode (or recording pause mode). The step gain near the recording mode and the step gain near the recording standby mode (or the recording pause mode) are made different from each other so that the cancellation pull-in speed is smaller than the noise cancellation pull-in speed in the recording mode. And in the vicinity of the recording mode, the digital noise correlation signal is supplied to the subtraction means so as to be switched. In the vicinity of the recording standby mode (or the recording pause mode), the switching means is controlled so that the digital noise correlation signal is not supplied to the subtraction means. Without being affected by disturbances
A noise reduction device for a recording apparatus capable of reliably reducing a noise component mixed in an audio signal and capable of reliably reducing a noise component mixed in an audio signal even when the operation mode of the recording apparatus changes. Can be.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a specific example of an embodiment of the present invention.

FIG. 2 is a block diagram showing a partial configuration of the specific example of FIG. 1;

FIG. 3 is a block diagram showing a specific configuration of the adaptive filter of the specific example of FIG. 1;

FIG. 4 is an explanatory diagram of transition of a VTR mode and step gain control.

FIG. 5 is an explanatory diagram of VTR mode transition and cancel on / off control.

FIG. 6 is a block diagram showing another specific example of the embodiment of the present invention.

[Explanation of symbols]

ML, MR microphone, 3L, 3R A / D converter, 4L, 4R noise cancellation circuit, 5 subtraction means, 6 adaptive filter, 7 on / off switch, 8 variable gain amplifier circuit, 9 limiter, 10L, 10R output terminal, 11 rotation Drum, 12 rotating magnetic head, 1
3 drum motor, 14 magnetic tape, 15 microcomputer.

Claims (14)

[Claims] 1. An energy wave generating means driven by a drive signal from a drive signal source to generate an energy wave, wherein a noise component mixed into an information signal is reduced based on the energy wave from the energy wave generating means. A noise reduction device for an electronic device, wherein a fundamental wave having a frequency equal to a frequency of an energy wave from the energy wave generating means and a harmonic thereof are based on a drive signal from the drive signal source and a noise error component. An adaptive filter for generating a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the information signal based on the energy wave from the energy wave generating means; and The digital noise correlation signal is subtracted from the input digital information signal Subtracting means for obtaining an output digital information signal in which the digital noise component is reduced; and varying the step gain of the output digital information signal from the subtracting means to supply the error noise component to the adaptive filter. A noise reduction device for an electronic device, comprising a variable gain means. 2. The noise reduction device for an electronic device according to claim 1, wherein said variable gain means sets a step gain near a transition period of an operation mode of said electronic device to a predetermined step gain near the operation mode. A noise reduction device for an electronic device, wherein a pull-in speed of noise cancellation near a transition period of the operation mode is set to be higher than a pull-in speed near the operation mode. 3. The noise reduction device for an electronic device according to claim 1, wherein the operation mode of the electronic device is a first operation mode in which a level of a noise component mixed in the information signal is high.
When the variable gain means changes between the second operation mode and the second operation mode in which the level of the noise component mixed in the information signal is lower than the operation mode of the second operation mode, the variable gain means cancels the noise in the second operation mode. The step gain near the first operation mode and the step gain near the second operation mode are mutually set so that the pull-in speed is smaller than the noise canceling pull-in speed in the first operation mode. A noise reduction device for an electronic device, wherein the noise reduction device is configured to make the noise reduction different. 4. An energy wave generating means driven by a drive signal from a drive signal source to generate an energy wave, wherein a noise component mixed in the information signal is reduced based on the energy wave from the energy wave generating means. A noise reduction device for an electronic device, wherein a fundamental wave having a frequency equal to a frequency of an energy wave from the energy wave generating means and a harmonic thereof are based on a drive signal from the drive signal source and a noise error component. An adaptive filter for generating a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the information signal based on the energy wave from the energy wave generating means; and The digital noise correlation signal is subtracted from the input digital information signal A subtraction means for obtaining an output digital information signal in which the digital noise component is reduced; and a switching means for controlling supply and non-supply of the digital noise correlation signal from the adaptive filter to the subtraction means. A noise reduction device for an electronic device, comprising: 5. The noise reduction device for an electronic device according to claim 4, wherein the operation mode of the electronic device is a first operation mode in which a level of a noise component mixed in the information signal is high.
When the digital noise correlation signal changes between the first operation mode and the second operation mode in which the level of the noise component mixed in the information signal is lower than the operation mode of The switching means is controlled so as to be supplied to the subtraction means, and the switching means is controlled so that the digital noise correlation signal is not supplied to the subtraction means near the time of the second operation mode. A noise reduction device for an electronic device, comprising: 6. An energy wave generating means driven by a drive signal from a drive signal source to generate an energy wave, wherein a noise component mixed in the information signal is removed based on the energy wave from the energy wave generating means. A noise reduction device for an electronic device, wherein a fundamental wave having a frequency equal to a frequency of an energy wave from the energy wave generating means and a harmonic thereof are based on a drive signal from the drive signal source and a noise error component. An adaptive filter for generating a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the information signal based on the energy wave from the energy wave generating means; and The digital noise correlation signal is subtracted from the input digital information signal Subtracting means for obtaining an output digital information signal in which the digital noise component is reduced; and varying the step gain of the output digital information signal from the subtracting means to supply the error noise component to the adaptive filter. A noise reduction device for an electronic device, comprising: a variable gain unit; and a switching unit that controls supply and non-supply of the digital noise correlation signal from the adaptive filter to the subtraction unit. 7. The noise reduction device for an electronic device according to claim 6, wherein the operation mode of the electronic device includes a first operation mode having a high level of a noise component mixed in the information signal, and
When the variable gain means changes between the second operation mode and the second operation mode in which the level of the noise component mixed in the information signal is lower than the operation mode of the second operation mode, the variable gain means cancels the noise in the second operation mode. The step gain near the first operation mode and the step gain near the second operation mode are mutually set so that the pull-in speed is smaller than the noise cancellation pull-in speed in the first operation mode. In the vicinity of the first operation mode, the switching means is controlled so that the digital noise correlation signal is supplied to the subtraction means. In the vicinity of the second operation mode, The switching means is controlled so that the digital noise correlation signal is not supplied to the subtraction means. Noise reduction apparatus of the equipment. 8. A recording apparatus comprising: a microphone; and rotating means driven by a motor, wherein the noise component mixed into an audio signal from the microphone is reduced and recorded through the microphone based on noise caused by rotation of the rotating means. A noise reduction device for a recording device adapted to record on a medium, comprising a fundamental wave equal to the rotation frequency of the rotation unit and a harmonic thereof based on a drive signal and a noise error component supplied to the motor, An adaptive filter that generates a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the audio signal based on noise due to rotation of the input digital audio obtained by digitally converting the audio signal The digital noise correlation signal is subtracted from the signal to obtain the digital noise Subtraction means for obtaining an output digital audio signal having a reduced component, and variable gain means for varying the step gain of the output digital audio signal from the subtraction means and supplying the error noise component to the adaptive filter. A noise reduction device for a recording apparatus. 9. The noise reduction apparatus for a recording apparatus according to claim 8, wherein the variable gain means sets a step gain near a transition period between a recording mode and a recording pause mode of the recording apparatus in the recording mode. A step gain different from the predetermined step gain near the time, the pull-in speed of the noise canceling near the transition period between the recording mode and the recording pause mode is set to be higher than the pull-in speed near the recording mode. A noise reduction device for a recording device, comprising: 10. The noise reduction apparatus for a recording apparatus according to claim 9, wherein said variable gain means sets a noise canceling pull-in speed in said recording pause mode smaller than a noise canceling pull-in speed in said recording mode. So that
A noise reduction device for a recording apparatus, wherein a step gain near the recording mode and a step gain near the recording pause mode are different from each other. 11. A recording apparatus comprising: a microphone; and rotating means driven by a motor, wherein a noise component mixed into an audio signal from the microphone is reduced and recorded through the microphone based on noise caused by rotation of the rotating means. A noise reduction device for a recording device adapted to record on a medium, comprising a fundamental wave equal to the rotation frequency of the rotation unit and a harmonic thereof based on a drive signal and a noise error component supplied to the motor, An adaptive filter that generates a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the audio signal based on noise due to rotation of the input digital audio obtained by digitally converting the audio signal The digital noise correlation signal is subtracted from the signal to obtain the digital noise correlation signal. Subtraction means for obtaining an output digital audio signal with a reduced noise component; and switching means for controlling supply and non-supply of the digital noise correlation signal from the adaptive filter to the subtraction means. Noise reduction device for recording devices. 12. The noise reduction device for a recording device according to claim 11, wherein the operation mode of the recording device changes between a recording mode and a recording standby mode in which a noise component is not mixed in the audio signal. In this case, the switching unit is controlled so that the digital noise correlation signal is supplied to the subtraction unit around the recording mode, and the digital noise correlation signal is subtracted around the recording standby mode. A noise reduction apparatus for a recording apparatus, wherein the switching means is controlled so as not to be supplied to the means. 13. A recording apparatus comprising: a microphone; and rotating means driven by a motor, wherein noise components mixed into an audio signal from the microphone are reduced and recorded through the microphone based on noise caused by rotation of the rotating means. A noise reduction device for a recording device adapted to record on a medium, comprising a fundamental wave equal to the rotation frequency of the rotation unit and a harmonic thereof based on a drive signal and a noise error component supplied to the motor, An adaptive filter that generates a digital noise correlation signal having a correlation with a digital noise component based on a noise component mixed into the audio signal based on noise due to rotation of the input digital audio obtained by digitally converting the audio signal The digital noise correlation signal is subtracted from the signal to obtain the digital noise correlation signal. Subtraction means for obtaining an output digital audio signal having a reduced noise component; variable gain means for varying the step gain of the output digital audio signal from the subtraction means and supplying the error noise component to the adaptive filter; A switching unit that controls supply and non-supply of the digital noise correlation signal from the adaptive filter to the subtraction unit. 14. The noise reduction apparatus for a recording apparatus according to claim 13, wherein the operation mode of the recording apparatus is a recording mode and a recording standby mode in which noise is not mixed in the audio signal (or
When changing between the recording mode and the recording pause mode in which the level of the noise component mixed into the audio signal is smaller than in the recording mode, the variable gain means sets the recording standby mode (or the recording pause mode). The step gain in the vicinity of the recording mode and the step gain in the vicinity of the recording standby mode (or the recording pause mode) are set so that the pull-in speed of the noise cancellation at the time is smaller than the pull-in speed of the noise cancellation in the recording mode. The step gains are made different from each other. In the vicinity of the recording mode, the switching means is controlled so that the digital noise correlation signal is supplied to the subtracting means, and the recording standby mode (or the Near the recording pause mode), the digital noise correlation signal is supplied to the subtraction means. No way, noise reduction device for a recording apparatus which is characterized in that so as to control the switching means.