JPH05308553

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DESCRIPTION JPH05308553
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
recording apparatus for a video camera, and more particularly to a recording apparatus for a
video camera capable of highly realistic recording at zoom shooting.
[0002]
2. Description of the Related Art Some recent consumer video cameras obtain a zoom function by
digitizing and processing a video signal. Such a zoom function is called an electronic zoom
function, which enables zooming up to about 8 times.
[0003]
In a video camera equipped with an electronic zoom function, by combining the zoom lens with
the electronic zoom function, a zoom function with a higher magnification than the zoom
function of the optical system can be obtained. For example, combining a 12x zoom lens with an
8x electronic zoom function enables continuous zooming up to about 100x.
[0004]
Also, in recent years, video cameras equipped with a recording device have been widely used in
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order to enhance video effects.
[0005]
By the way, when performing zoom photography in a video camera equipped with a recording
device, the focus of the camera is focused on a distant subject, and the subject is projected on
one surface, but the sound to be recorded is recorded. The position where the sound is collected
is the position of the camera, and the image of the subject and the focus of the recording do not
match, and a great dissatisfaction is felt in enhancing the sense of reality.
[0006]
Further, since the sound of a distant subject is recorded at a low level, it can not be balanced with
the zoomed-in image, and a sense of discomfort is felt between the image and the audio level.
[0007]
The present invention has been made in view of the above-described circumstances, and an
object of the present invention is to provide a recording apparatus of a video camera capable of
performing highly realistic recording at the time of zoom shooting.
[0008]
SUMMARY OF THE INVENTION In order to achieve the above object, the present invention
focuses on a microphone capable of controlling directivity and focusing of the microphone on the
subject in synchronization with focusing on the subject of a video camera. And an audio signal
processing unit.
[0009]
Furthermore, a means for detecting the zooming magnification upon zooming of the subject, and
an AGC circuit for adjusting the recording level corresponding to the zooming magnification may
be provided.
[0010]
Here, as microphones capable of controlling the directional characteristics, microphone arrays
comprising a large number of microphone elements, parametric microphones having an array
structure of ultrasonic transducers, etc. can be mentioned as an example, for example, in the case
of a microphone array The directivity is controlled by delaying or weighting the output of each
microphone element.
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[0011]
Focusing on the subject of the video camera means adjusting the focus distance to the position of
the subject by zooming, and this zooming may be either optical zooming or zooming with an
electronic zoom function. It may be zooming combined with an electronic zoom function.
[0012]
Also, focusing on the directional characteristics of the microphone on the subject means that the
sound is actually collected at the position of the camera, but the directional characteristics of the
microphone are controlled and the apparent sound collecting position (hereinafter referred to as
a pseudo sound collecting position) .
) To align the subject position.
In other words, it means controlling the directivity characteristic of the microphone to obtain an
audio signal as if it were collected at the position of the object.
[0013]
In the present invention, the sound is collected at the position of the video camera through the
microphone capable of controlling the directional characteristic, but the audio signal processing
unit focuses the directivity of the microphone on the subject in conjunction with the focusing of
the subject. It is possible to obtain an audio signal as if it were collected at the position of the
subject.
[0014]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A recording apparatus for a video
camera according to an embodiment of the present invention will be described in detail with
reference to FIGS. 1 to 4. First, the outline will be described based on FIG.
As shown in the block diagram of FIG. 1, the distance between the camera and the subject A, that
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is, the focus distance is detected by the focus distance detection unit 2 based on the output of the
focus distance measurement sensor 1.
[0015]
Audio is collected by a microphone array 3 described later, and an audio signal output from the
microphone array 3 is subjected to focusing signal processing described later by an audio signal
focus processor 4.
[0016]
Also, based on the detected focus distance, the video signal focus processor 5 outputs a focus
control signal to control the zoom motor so that the focal position of the lens becomes the
position of the subject A, and the video signal is output via the lens. I am trying to get it.
The video signal is subjected to electronic zoom processing by the video signal focus processing
unit 5 as necessary, and then output from the video signal focus processing unit 5 to the
recording medium.
[0017]
The zoom motor is additionally provided with an encoder 6 for detecting the amount of
displacement thereof, the zoom magnification detection section 7 detects the zoom magnification
based on the output of the encoder 6, and the gain control signal detection section based on the
zoom magnification 8 calculates a gain control signal, and an audio signal which has been
subjected to focus processing by the audio signal focus processing unit 4 is subjected to
automatic gain control by an AGC (Auto Gain Control) circuit 9 based on the calculation result.
The microphone array 3 includes a large number of microphone elements M1, M2,..., MN
arranged concentrically in N stages as shown in the schematic view of FIG.
[0018]
As shown in the block diagram of FIG. 3, the audio signal focus processing unit 4 includes delay
circuits 411, 412,... 41N of the number corresponding to the number of stages of the microphone
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array 3, weighting circuits 421, 422,. , And an adder 43. The outputs of the microphone elements
M1, M2,..., MN are input to the corresponding delay circuits 411, 412,.
[0019]
Here, as shown in the schematic view of FIG. 4, assuming that the distance between the
respective microphone elements M1, M2,..., MN is d and the focus distance is f, each position
from the subject A, ie, each from the focus position. The distances to the microphone elements M
1, M 2,..., MN have a difference between the focus distance and ξ 1, ξ 2,.
[0020]
For this reason, time differences t1, t2,..., TN are generated in the audio signals obtained from the
microphone elements M1, M2,.
[0021]
In order to place the pseudo sound collection position at the focus position, the delay time of
each delay circuit 411, 412,... 41N may be set so as to eliminate these time differences. The delay
time Tk of the delay circuit 41k corresponding to the element Mk may be set in accordance with
the following equation (1).
[0022]
Tk = t N-tk = (ξ N-/ k) / C = {((N · d) 2 + f 2) 1/2-((k · d) 2 + f 2) 1/2} / C
[0023]
The weighting circuits 421, 422,..., 42N increase in number as the number of microphone
elements M1, M2,. The audio signal weighting is performed so that the signal output from each
stage has the same amplitude level.
[0024]
The addition circuit 43 adds all the audio signals of the respective stages obtained in this way,
and outputs the addition result to the AGC circuit 9.
[0025]
According to the recording device of the video camera, the delay circuits 411, 412,. Since the
volume dispersed to the microphone elements of each stage by weighting circuits 421, 422,. As
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you can, you can record audio signals, and you can record with a sense of reality.
[0026]
Further, according to the recording apparatus of the video camera, the automatic gain control is
performed by the AGC circuit 9 corresponding to the zoom magnification, the sound level of the
distant object is increased, and the sense of distance to the object received from the video and
the sound This makes it possible to reduce the gap between the subject and the sense of distance
to the subject, eliminate the sense of discomfort between the image and the sound level, and
make a more realistic recording.
[0027]
In the above embodiment, the microphone array 3 is used as a microphone capable of controlling
the directivity characteristic, but it is also possible to use a parametric microphone
(superdirective microphone) instead.
The parametric microphone itself has an array structure of ultrasonic transducers, so that its
directivity can be controlled to perform focusing of the audio signal, and since it has sharp
directivity, it has an image and It is possible to further reduce the sense of incongruity with the
voice and to make recording with a more realistic feeling.
[0028]
As described above, according to the present invention, there is provided a microphone capable
of controlling the directivity characteristic, an audio signal processing unit for focusing the
directivity characteristic of the directional microphone onto the object in synchronization with
the focusing of the video camera onto the object; By controlling the directional characteristics of
the microphone at the time of zoom shooting, it is possible to make the pseudo sound collection
position coincide with the focus position and to make a highly realistic recording.
[0029]
Particularly, in the present invention, in the case of including means for detecting the zooming
magnification during zooming of the subject and an AGC circuit for adjusting the recording level
corresponding to the zooming magnification, the recording level of the audio signal of the subject
corresponds to the zoom magnification. The gap between the sense of distance to the subject
received from the video and the sense of distance to the subject received from the audio can be
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reduced by gain adjustment and enlarged, and the sense of reality can be further enhanced.
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