JPH048097A - Magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To generate a sound signal with less noise by providing a low cut filter to a post stage of a unidirectional microphone and providing a high cut filter to a post stage of a omnidirectional microphone so as to synthesize sound signals passing through both filters. CONSTITUTION:Low frequencies of a sound collected by unidirectional microphones 201,202 whose sensitivity against noise such as wind or vibration sound are eliminated by low cut filters 204, 205. Then the characteristic of the unidirectional microphones is improved. Moreover, only low frequencies not giving much effect onto the directivity among sound collected by an omnidirectional microphone 203 having an unsharp directivity but whose sensitivity against wind or vibration sound is suppressed by 10-20dB lower than that of the unidirectional microphone are passed by a high cut filter 206. Thus, high frequencies collected by the unidirectional microphone with excellent directivity and low frequencies collected by the non-directional microphone 203 are synthesized to attain recording with less noise in a VTR block 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a magnetic recording and reproducing device for recording audio signals.

BACKGROUND OF THE INVENTION In recent years, magnetic recording and reproducing devices are required to have not only high image quality but also high sound quality, and as microphones, high-fidelity stereo microphones are increasingly being installed in the main body of the device.

An example of the above-mentioned conventional magnetic recording/reproducing device will be described below with reference to the drawings. 4 and 5 show the configuration of a conventional magnetic recording/reproducing device and a stereo microphone. In Figures 4 and 6, 1 is a camera block, 2 is a stereo microphone, and 3 is a VTR.
It is a block. 11 is a video signal, 21 is a right channel (Rch) audio signal, and 22 is a left channel (Lah) audio signal. In FIG. 5, 201 is a unidirectional microphone for Rch, and 202 is a unidirectional microphone for Lch. 11 is a video signal sent from the camera clock 1 to the VTR block 3, and 21 and 22 are audio signals sent from the stereo microphone 2 to the VTR block 3, which are an Rch audio signal and an Lch audio signal, respectively.

The operation of the conventional magnetic recording/reproducing apparatus configured as described above will be described below.

Although not shown, the camera block 1-E is equipped with a motor that moves the lens during focusing.

The focused and captured video is converted into an electrical signal and the video signal 11 is sent to the VTR block 3.

At the same time, the Rch unidirectional microphone 201 and L
The sounds collected by the channel unidirectional microphone 202 are an Rch audio signal 21 and an Lch audio signal 22, respectively.
and sent to VTR block 3. In this way, video signals and audio signals are sent to the VTR block 3 to operate the VTR.

Problems to be Solved by the Invention However, in the above conventional configuration, the unidirectional microphone 2o
1 and 202 are highly sensitive to noise such as wind and vibration, so the unidirectional microphones 201 and 202 collect wind noise and the vibration sound of the motor generated when focusing with the camera block 1. It had the following drawback.

The present invention solves the above-mentioned conventional problems by improving the low-frequency characteristics that are the main frequency band of noise such as wind and vibration noise,
An object of the present invention is to provide a magnetic recording and reproducing device capable of performing high-fidelity recording without impairing the frequency characteristics and directional characteristics of recorded speech.

Means for Solving the Problems In order to solve the above-mentioned conventional problems, the magnetic recording and reproducing apparatus of the present invention has a stereo microphone, and the stereo microphone includes a plurality of unidirectional microphones, and a plurality of unidirectional microphones. an omnidirectional microphone located between the plurality of unidirectional microphones, and an audio signal of each of the plurality of unidirectional microphones provided after the plurality of unidirectional microphones. a plurality of low-cut filters that cut low-frequency components of the audio signal of the omnidirectional microphone; a high-cut filter that is provided after the omnidirectional microphone and cuts the high-frequency components of the audio signal of the omnidirectional microphone; The audio signal is characterized in that each audio signal is synthesized with an audio signal that has passed through the high-cut filter.

Effect: When recording with this configuration, the low-frequency range, which is the main frequency range of wind and vibration sounds, is removed from the sound collected by the unidirectional microphone, and the omnidirectional microphone removes it. The high-frequency range of the collected audio is removed by the high-cut filter, and the audio signal that has passed through the high-cut filter and the audio signal that has passed through the low-cut filter are synthesized, so the synthesized audio signal has no loss of frequency characteristics or directivity. This results in an audio signal with less noise.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, and FIG. 2 is a frequency characteristic diagram of an audio signal. In Figure 1, 1 is a camera block, 12 is a stereo microphone, and 3 is a VTR block. 4 for stereo microphone 12 and unidirectional microphone 201. L
Unidirectional microphone for channel 2o2. Omnidirectional microphone 2o3° low cut filters 204 and 205.
Ha! -)) Consisting of a throat filter 206 and a mixer 2oγ, the Rch unidirectional microphone 20
The unidirectional microphone 202 for 1 and Lchs generally has a sensitivity higher than that of the omnidirectional microphone 203 to wind and vibration sounds by 1 odB to 2 odB. Low cut filters 204 and 205 are connected to the rear stage of the Rch unidirectional microphone 201 and the rear stage of the Lch unidirectional microphone 202, and the low cut filter 20
4. The high-frequency audio signals 24 and 26 that have passed through the input and output terminals 205 pass through a resistor 31 (resistance value R31) or a resistor 33 (resistance value R33), respectively, and are input to the mixer 2o.

Further, the omnidirectional microphone 203 is located between the Rch unidirectional microphone 201 and the Lch unidirectional microphone 202.
A high-cut filter 206 is connected to the rear stage of 3, and the low-frequency audio signal 26 that has passed through the high-cut filter 206 is divided equally by two resistors 32 (resistors VLR 32), and these two equally divided audio signals are each connected to a resistor 31. Or it is synthesized with the audio signal that has passed through the resistor 33 and sent to the mixer 2.
It is set to enter 07. The mixer 207 is composed of a feedback type operational amplifier having a feedback resistor 34 (resistance value R34). Regarding the resistance value, R
31, R3□, R33, and R34 are all the same value.

In FIG. 2, (a) is a frequency characteristic diagram of the audio signal 24 that has passed the low-cut filter 204 and the audio signal 25 that has passed the low-cut filter 205, and (b) is a frequency characteristic diagram of the audio signal 26 that has passed the high-cut filter 206. (C) is a frequency characteristic diagram of the audio signals 27 and 28 that have passed through the mixer 20a.

The operation of the magnetic recording/reproducing apparatus configured as described above will be described below.

The sound collected by the Rch unidirectional microphone 201 is converted into an audio signal 21, and the sound is passed through a low-cut filter 20.
As shown in FIG. 2(a), the high-frequency audio signal 24 becomes a high-frequency audio signal 24 in which only the high-frequency components are extracted, passes through a resistor 31, and reaches point p. The sound collected by the unidirectional microphone 202 for Lah is converted into an audio signal 22, which passes through a low-cut filter 205 and becomes a high-frequency audio signal 25. This high-frequency audio signal 25 is converted into a high-frequency audio signal 24. Similarly, it is represented by a frequency characteristic diagram as shown in FIG. 2(a).

It passes through the resistor 33 and reaches point q. The sound collected by the omnidirectional microphone 203 is converted into an audio signal 23,
A low-frequency audio signal 26 is passed through a high-cut filter 206 and only low-frequency components are extracted as shown in FIG. 2(b).
Therefore, the low frequency audio signal 26 is equally divided by the resistor 32 and reaches the p point or the q point, respectively. Resistance 31 at point p
The high frequency audio signal that has passed through the resistor 32 and the low frequency audio signal that has passed through the resistor 32 are configured, and the synthesized audio signal is sent to the mixer 207.
becomes the input. Similarly, at point q, the audio signal that has passed through the resistor 33 and the low-frequency audio signal that has passed through the resistor 32 are synthesized, and the synthesized audio signal is input to the mixer 207. The mixer 207 has a ratio of the resistance value R34 of the resistor 34 and the resistance value R31 of the resistor 31, and the ratio of the resistance value R34 and the resistance value R3 of the resistor 33.
The gain for Rch and Lch is determined by the ratio of 3.

In addition, since the input impedance of this mixer 207 is sufficiently larger than the output impedance, the left and right high-frequency audio signals 26 and 24 are mixed in the audio signals at points p and q that are input to the mixer 207. The effect of shrinkage can be ignored.

Therefore, the audio signals at points p and q that are input to the mixer 207 are input to the mixer 207 while maintaining a sufficient degree of separation, and are amplified by the gain of the mixer described above to become audio signals 27 and 28, respectively. As shown in FIG. 2(C), the audio signals 27 and 28 have a composite cutoff characteristic where the low frequency component and the high frequency component are at the same sound pressure level, and the frequency is 500 H.
Intersect at z.

The audio signals 27 and 28 are sent to the VTR block 3, but even if the input impedance of the VTR block 3 fluctuates, the output impedance of the mixer 207 is sufficiently low, so this fluctuation has no effect on the synthesis of the audio signals before the mixer 20. It has no effect.

If the stereo microphone 2 of this embodiment is configured as described above, the sensitivity to noise such as wind and vibration noise will be high.The low frequency range of the sound collected by the unidirectional microphones 2o1 and 202 will be filtered by a low-cut filter. 204 and 2
By removing it with 05, the characteristics of a unidirectional microphone are improved, and although the directivity is dull, the sensitivity to wind and vibration sounds is a unidirectional microphone! 1l11゜dB~20
Among the sounds collected by the omnidirectional microphone 203 that can be suppressed to a low dB, only the low frequency range that does not have much influence on the directivity can be passed through the high-cut filter 206.

Therefore, sensitivity to high frequencies and noise collected by a unidirectional microphone with excellent directivity is kept low, allowing for excellent recording.

Note that if the noise such as wind or vibration is too strong, the low-frequency audio signal 26 that has passed through the pi-cut filter 206 can be cut by the low-cut switch 208 as in the stereo microphone 13 shown in FIG. Noise can be removed more effectively by simply adding a low-cut switch 208 to the stereo microphone 12.

Effects of the Invention As described above, the magnetic recording/reproducing device of the present invention has a stereo microphone, in which a low-cut filter is provided after the unidirectional microphone, and a high-cut filter is provided after the omnidirectional microphone. Since the audio signal and the audio signal that has passed the high-cut filter are synthesized, the low-frequency characteristics, which are the frequency band of noise such as wind and vibration noise, are improved, and the audio signal with less noise is generated without impairing the frequency characteristics or directional characteristics. Can be generated.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a magnetic recording/reproducing apparatus according to an embodiment of the present invention, FIG. 2 is a frequency characteristic diagram of an audio signal, and FIG. 3 is a block diagram of a stereo microphone of a magnetic recording/reproducing apparatus according to an embodiment of the present invention. FIG. 4 is a block diagram of a conventional magnetic recording/reproducing apparatus, and FIG. 5 is a block diagram of the microphone shown in FIG. 4. 1... Camera block, 201, 202...
...Unidirectional microphone, 2o3...Omnidirectional microphone, 204,205...Low cut filter, 206...High cut filter, 208... Low cut switch, 3...
...VTR block.

Claims (1)

[Claims] A magnetic recording/reproducing device having a stereo microphone, wherein the stereo microphone includes a plurality of unidirectional microphones, an omnidirectional microphone located between the plurality of unidirectional microphones, and a plurality of unidirectional microphones. a plurality of low-cut filters provided after the directional microphone to cut low frequency components of the tone signals of each of the plurality of unidirectional microphones; A magnetic recording and reproducing device comprising: a high-cut filter that cuts high-frequency components of an audio signal from a microphone; and an audio signal that has passed through the plurality of low-cut filters and an audio signal that has passed through each of the high-cut filters are synthesized. Device.