JPH03173298

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DESCRIPTION JPH03173298
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
stereo zoom microphone which is mounted on a camera having a zoom function of an image
such as an integrated video camera and the like and which picks up a sound in synchronization
with the image. 2. Related Art Conventional integrated video cameras are equipped with
nondirectional microphones or unidirectional microphones, and perform recording synchronized
with recording. Also, in the past, it has been practiced to increase the sound collection quality by
mixing and picking up a sense of perspective and a sense of spread with an external microphone.
SUMMARY OF THE INVENTION However, the above-mentioned conventional microphones for
integrated video cameras are monodirectional, monophonic microphones using a monophonic
microphone, lack of realism, and clearly pick up the target sound. There was a problem I could
not do. In addition, when using an external microphone, there was a problem that operation was
complicated. The present invention solves the above-mentioned conventional problems, and
provides a stereo zoom microphone that can realize a zoom sound pickup with a simple
configuration that is matched to the perspective and spread of the image in conjunction with the
zooming of the camera. It is Means for Solving the Problems In order to achieve the above object,
the present invention provides a plurality of unidirectional microphone units, combining means
for combining the outputs of the microphone units and outputting a plurality of combined
signals, and the combining means. Filter means for cutting the low band of at least one
synthesized signal of the plurality of synthesized signals outputted by the plurality of signals,
signal level control means for controlling the level of each of the plurality of synthesized signals,
and control signal according to the zooming operation of the lens And means for controlling the
signal level control means by the control signal. The present invention is configured as described
above, and since the level control means is controlled in conjunction with the zooming operation
of the lens, it is possible to pick up sound with a sense of reality at wide angle, and pick up with
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clarity at telephoto. Is possible. Embodiment An embodiment of the present invention will be
described with reference to FIGS. 1 and 2. In FIG. 1, 1 ° 2 is a unidirectional microphone unit
having a directivity pattern as shown, and this microphone unit 1.2 is arranged so that the main
axis angle is 90. A microphone amplifier 3.4 amplifies the output of the microphone unit 1.2. The
outputs of the microphone amplifiers 3.4 are applied to the subtractors 7 and 8 as well as to the
attenuators 5 and 6, respectively.
The attenuator 5 ° 6 attenuates the output level of the microphone amplifier 3.4 by half. The
subtractor 7 mixes the output of the microphone amplifier 3 with the output of the attenuator 6
and outputs a composite signal to a terminal 9. On the other hand, the subtractor 8 mixes the
output of the microphone amplifier 4 with the output of the attenuator 5 and outputs a
composite signal to the terminal 10. An adder 11 adds the outputs of the subtractors 7 and 8 and
outputs a combined signal. The attenuator 5.6, the subtractor 7 ° 8 and the adder 9 constitute a
combining means, and three combining signals are output from this combining means. Reference
numeral 12 denotes a low cut amplifier having low pass cut characteristics. 13, 14, and 15. Each
of the electronic polymes 13 (the output of the local amplifier 12 is applied, the output of the
subtractor 7 is applied to the electronic polyem 14, and the subtracter 8 is applied to the
electronic volume 15. The output of is applied. 16.17 is an adder, and the adder 16 adds the
outputs of the electronic volumes 13 and 14, and the other adder 17 adds the outputs of the
electronic volumes 13 and 15. A zoom lens 18 and an optical encoder 19 output a signal
corresponding to the zooming of the zoom lens 18. Reference numeral 20 denotes a control
voltage generator, which is controlled by the control signal output from the control voltage
generator 20 to control the electronic volume 13, 14.15. Next, the operation of the above
embodiment will be described. The signal collected by the microphone unit 1.2 is applied to the
subtractor 7.8 through the microphone amplifier 34 and the attenuators 5 and 6, and the
subtracter 7 outputs a composite signal of (L-1 / 2R). The subtracter 8 outputs a composite
signal of (R-1 / 2L). This is a synthesizing method for obtaining the directivity equivalent to that
of the MS stereo microphone, and is a signal component at the wide angle. Also, the signal added
by the adder 11 is applied to the low cut amplifier 12 of the low cut-off frequency fL (300 to 500
Hz), and the low-pass frequency is cut while amplifying 6 to 10 dB with I KHz. It is used as a
signal component of time. The position of the zoom lens 18 of the video camera is detected by
the optical encoder 19 and voltage conversion is performed by the control voltage generator 20
to generate a control voltage for the electronic polygons 13 and 14.15. 2A shows the gain
characteristics of the electronic volume 14.15, and FIG. 2B shows the gain characteristics of the
electronic volume 13.
As shown in FIG. 2A, the electronic volume 14.15 increases in gain as the zoom lens 18 is at the
wide-angle position, and the electronic volume 13 increases in gain as the zoom lens 18 is at the
telephoto position. It is controlled. The wide-angle signal and the narrow-angle signal whose level
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is controlled by the control voltage are synthesized by the adder 1617 and output. That is, when
the zoom lens 18 moves to the inter-angle position, the output level of the electronic polymes 13
becomes high, the output level of the electronic polymes 14.15 becomes low, and the stereo
sound is changed to the monaural sound. Since the low range of is cut off and the volume is
increased by 6 to 10 dB, the intelligibility to ambient noise is improved, and the effect of zooming
up distant sounds can be obtained. On the other hand, when the zoom lens 18 is moved to the
wide-angle position, the output level of the electronic volume 13 is lowered and the output level
of the electronic volume 14.15 is increased. Since the low-frequency range is raised, ambient
noise can be picked up, and it becomes possible to pick up a sound that gives a sense of stereo
and a sense of reality. As described above, according to this embodiment, the zooming effect of
sound according to the zooming operation of the zoom lens can be obtained. The present
invention is configured as described above, and has the advantage of being able to pick up sound
according to the wide angle and the included angle in conjunction with the zooming operation of
the zoom lens with a simple configuration.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a block diagram of a stereo zoom microphone according to an embodiment of the
present invention, and FIGS. 2A and 2B are diagrams showing the characteristics of the electronic
volume of the microphone.
1.2 · · Microphone unit, 3.4 · · Microphone amplifier, 5.6 · · Attenuator, 7.8 · · · · · · · · Adder, 12 · · ·
Low cut amplifier, 13.14.15 · · · · Electronic volume, 16.17 · · Adder, · · · Zoom lens, 19 · · Optical
encoder, 20 · · · Control voltage generator.
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