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DESCRIPTION JPH06133387

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DESCRIPTION JPH06133387
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
audio signal processing apparatus for processing an audio signal inputted by a built-in
microphone or an external microphone.
[0002]
2. Description of the Related Art In the following, as an audio signal processing apparatus, a
camera integrated VTR capable of recording both an image pickup signal and an audio signal will
be described as an example.
[0003]
The camera-integrated VTR has recently been miniaturized, and along with that, the mechanical
distance between various motors (for example, a focus lens drive motor, a zoom lens drive motor,
a motor of a VTR unit, etc.) generating noise is Inevitably, proximity advances.
There is also a limit to the reduction of driving noise of motors and the like.
[0004]
Therefore, when the voice is recorded by the built-in microphone of the camera integrated type
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VTR thus miniaturized, the motor driving noise and the like which are not desired to be recorded
are recorded together.
[0005]
Therefore, a camera integrated type VTR has already been proposed in which the frequency
characteristics and sensitivity of the built-in microphone and the characteristics of the audio
signal processing circuit are changed to record the drive noise so that the drive noise can not be
heard.
[0006]
In addition to the built-in microphone, the above-described camera integrated VTR is provided
with an external microphone connection terminal for inputting sound from the external
microphone.
[0007]
However, in the conventional camera-integrated type VTR, when sound is collected by the
external microphone, the processing circuit of the sound signal collected by the built-in
microphone is used as it is, so when using the external microphone Changes the frequency
characteristics etc. as well as the audio signal collected by the built-in microphone without
having to worry about the drive / vibration noise generated from the inside of the camera
(attenuating the frequency region of the drive / vibration noise Because of this, there was a
problem that it was not possible to record high-quality sound with an external microphone.
[0008]
Under the circumstances, it is an object of the present invention to provide an audio signal
processing apparatus in which high-quality audio signals can be input to either an internal
microphone or an external microphone.
[0009]
An audio signal processing apparatus according to the present invention is an apparatus for
inputting an audio signal by means of a built-in microphone or an external microphone built in
the apparatus and processing the input audio signal. Determining means for determining
whether the input audio signal is from the built-in microphone or the external microphone, and
frequency characteristic switching means for switching the frequency characteristic of the input
audio signal according to the output of the determining means And.
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[0010]
According to the invention, in either case where voice is recorded by the built-in microphone or
the external microphone, the frequency characteristic is switched to the optimum frequency
according to the microphone in use, so high-quality voice input is enabled.
[0011]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A camera integrated VTR
according to an embodiment of the present invention will be described below.
[0012]
FIG. 1 is a block diagram of a camera integrated VTR according to this embodiment.
[0013]
In FIG. 1, 1 is an optical system including a focus lens, 2 is a shutter for adjusting the aperture, 3
is an imaging device such as a CCD, and 4 is video signal processing for performing
predetermined signal processing on the output signal of the imaging device 3 A circuit 5 is a
recording processing circuit that performs predetermined processing to record video and audio
signals on the magnetic tape 7, 6 is a magnetic head, 7 is a magnetic tape, 8 is an output of the
video signal output from the imaging device 3 AE control circuit for adjusting the shutter 2 using
the lens, 9 is an AF control circuit for adjusting the focus of the focus lens of the optical system 1
using the output of the video signal output from the imaging device 3, and 10 is an optical
system 1, a motor for moving the focus lens 1, a display processing circuit 11 for multiplexing a
title display and the like on an imaging signal, and an electronic viewfinder 12 for displaying a
captured image etc. (hereinafter referred to as EV) Referred to as), the drum motor 13, 14 is a
drum servo 15 a capstan motor, 16 is a cap servo.
[0014]
A built-in microphone 17 applies a DC voltage to the output of the built-in microphone 17.
A switch 19 switches in synchronization with connection of the connection terminal on the
external microphone side to the external microphone connection terminal 18, a capacitor 20 for
removing a DC component, and a DC voltage detection circuit 21. It detects if you are collecting
sound with an external microphone.
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Reference numeral 22 denotes an amplifier, and 23 denotes a frequency characteristic switching
circuit which switches the frequency characteristic according to the output of the DC voltage
detection circuit 21.
That is, the frequency characteristic switching circuit 22 is controlled by the DC voltage detection
circuit 21.
[0015]
A method of audio processing input by the built-in microphone of the camera integrated VTR
configured as described above and audio processing input by the external microphone will be
described.
[0016]
First, a method of detecting whether an external microphone is connected to the external
microphone terminal will be described.
[0017]
FIG. 2 is a diagram for explaining the specific configuration of the switch 19.
[0018]
In FIG. 2, when the connection terminal on the external microphone side is not connected to the
external microphone connection terminal 18 on the camera side, the switch 19 is connected (see
FIG. 2A), and the audio signal of the built-in microphone is An audio signal is input to the
capacitor 20 and the DC voltage detection circuit 21.
[0019]
When the connection terminal on the external microphone side is inserted into the external
microphone connection terminal 18, the switch 19 is disconnected as shown in FIG. 2B, and the
audio signal of the external microphone is sent to the capacitor 20 and the DC voltage detection
circuit 21. It is input.
[0020]
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Next, the frequency of the sound taken in by the built-in microphone and the external
microphone is shown in FIG.
[0021]
As shown in FIG. 3, when voice is taken in by the built-in microphone, mechanical drive noise is
concentrated in the low frequency range, so the low frequency components are attenuated.
[0022]
Also, since the period (about 60 Hz) of the vertical synchronization signal and the period (about
15.6 kHz) of the horizontal synchronization signal used in the internal video signal processing
circuit affect the audio processing circuit, the high frequency component is a notch filter The low
frequency component is attenuated by the HPF to take drive noise and noise of the power source
(noise due to vibration) generated in the horizontal synchronization signal period.
That is, the frequency characteristic switching circuit 23 includes an HPF and a notch filter.
[0023]
On the other hand, when capturing audio with an external microphone, there is no need to worry
about mechanical drive noise inside the camera or power supply noise due to air vibration, so the
high frequency notch filter and the low frequency HPF are also removed to make it flat. The
frequency characteristic switching circuit 23 is controlled to have characteristics.
[0024]
Although the direct current voltage is applied to the output of the built-in microphone in the
present embodiment, it may be determined by applying the direct current voltage to the output
of the external microphone.
[0025]
Further, the frequency characteristic switching circuit 22 may be switched in conjunction with
the switch 19 described with reference to FIG.
[0026]
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As described above, the audio signal processing apparatus according to the present invention is
an apparatus for inputting an audio signal by the built-in microphone incorporated in the
apparatus or an external microphone and processing the input audio signal. It is determined
whether the input audio signal is from the built-in microphone or the external microphone, and
the frequency characteristic of the input audio signal is switched according to the determination
result. In either case of inputting voice with a microphone, high-quality voice input is enabled
because the frequency characteristic is switched to the optimum frequency according to the
microphone in use.
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