JPS6359300A - Video camera - Google Patents

Abstract

PURPOSE:To attain a sound collection with natural feeling corresponding to the distance of a sound source, and a state of zooming, by changing the directivity of a microphone, and a sound volume by using the output signals of a distance measuring instrument, and a zoom positioning encoder as a control signal. CONSTITUTION:By controlling the mixing ratio of a mixer 14, and the frequency characteristic of an equalizer 15 by the output signal of the distance measuring instrument 17, and controlling the gain of a variable amplifier 16 by the output signal of the zoom positioning encoder 9, the global directivity of the microphone, and the sound volume can be controlled based on the distance of an object, and the wide-angle/long-shot information of a zoom lens. By incresasing the sound volume of a variable directional microphone based on the output of the zoom positioning encoder 9, according to the switching of the focusing distance of a photographing zoom lens from a wide-angle side to a long-shot side, an effect in which a sound image also with a video approaches to this side, can be obtained, thereby, the sound collection with the natural feeling can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a microphone for a video camera.

Conventional technology Generally, a single omnidirectional or unidirectional microphone is used in a video camera, and its volume remains constant regardless of whether the video is zoomed.

Therefore, when you zoom in on someone who is close to you,
Even when zooming in on a bird that is far away, although the effect of being close to the subject can be achieved on the screen, the proximity effect of the audio is not accompanied, and the result is unnatural.

Conventionally, there has been a microphone shown in FIG. 3 as a microphone with improved directivity in order to improve the characteristics when zoomed in.

In FIG. 3, the microphone 21 is composed of three microphones 21a, 21b, and 21c having unidirectionality.

Two microphones 22a and 22c are arranged facing forward with respect to the sound source 22, and one microphone 22b is arranged facing backward.

The overall characteristics of these microphones are three directional characteristics as shown in FIG.

The omnidirectionality shown in FIG. 4a is obtained by combining microphones 22a and 22b.

Figure 4 shows the primary sound pressure gradient unidirectional characteristic, which is the characteristic of one microphone.

Figure 4C shows the secondary sound pressure gradient unidirectional characteristic, and the volume is displaced by rotating the zoom ring of the television camera.
When mixing the output from the microphones, the mixing ratio is varied by a predetermined amount to change the directivity.

(For example, Japanese Patent Application Laid-Open No. 56-35596.) Furthermore, as the directivity of a single microphone has become narrower, some have increased the sound volume. (For example, JP-A-56-506
(No. 98 Publication) Problems to be Solved by the Invention However, with conventional variable directional microphones, the directivity and volume are changed only in conjunction with the zooming operation, and there is no effect on the distance of the subject. It wasn't even considered. Originally, directional microphones collect distant sounds while excluding surrounding noise. Therefore, even if the directivity of the microphone is changed in accordance with the shooting angle of view, the volume remains constant, and a sufficient sound image zooming effect cannot be obtained.

In view of the above-mentioned problems, the present invention provides a video camera having a microphone having a function of realizing a natural zooming effect on a sound image.

Means for Solving the Problems In order to solve the above problems, the video camera of the present invention uses a variable directional microphone that mixes the outputs from at least two microphones and changes the directivity by changing the mixing ratio. and a distance measuring device that outputs a signal corresponding to the distance to the subject, and a mechanism for changing the directivity of the variable directional microphone according to the signal corresponding to the distance to the subject, and furthermore, a mechanism for changing the directivity of the variable directional microphone according to the signal corresponding to the distance to the subject. The volume of the microphone is changed based on the output of the encoder.

Effect: In the case of a subject located far away, by the above means,
Since the sound of the sound source is considered to be small, the directivity of the variable directional microphone is set to narrow directivity to remove noise around the sound source and collect only effective sound. In the case of a subject located at a close distance, the sound source is likely to be loud, so the variable directivity microphone is set to have a wide directivity to incorporate surrounding sounds. ↑As the focal length of the closest zoom lens changes from the wide-angle side to the telephoto side, the volume of the variable directional microphone is increased based on the output of the zoom position encoder (by doing so, the sound image becomes closer together with the image). The effect can be changed.

Embodiment Hereinafter, an embodiment of the video camera of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention.

In Fig. 1, 1 is a light emitting lens, 2 is a light receiving lens, and 3 is a light emitting lens.
1 is a light emitting element, and 4 is a light emitting element driving section that drives the light emitting element. Reference numeral 5 denotes a semiconductor device detection element, the output of which is input to an arithmetic unit 6. The output of the calculation unit 6 is a signal corresponding to the distance to the subject (hereinafter referred to as a distance signal).

) and is input to the analog/digital converter 7.

The distance measuring device 17 is formed with the above configuration. Further, 8 indicates a photographing zoom lens, and 9 is a zoom position encoder attached to the photographing zoom lens, which converts information on the focal length of the photographing zoom lens 8 into a 2-bit digital value and outputs it.

Reference numeral 10 indicates a unidirectional microphone A, and 1) a unidirectional microphone B, which is arranged with respect to the 10 microphones A in consideration of its spatial position. 12.13 are preamplifiers, and 14 is the preamplifier 12.1.
This is a mixer that mixes the outputs of three in an appropriate ratio. 15 is an equalizer, and 16 is a variable amplifier.

The operation of one embodiment will be described below with reference to the drawings.

The distance measuring device 17 applies the principle of triangulation, as described in detail in Japanese Patent Application Laid-Open No. 61-731)7, and projects infrared light toward the subject and captures the reflected light. The infrared light is guided onto the light receiving element through a lens, and the distance to the subject is calculated based on the position of the center of gravity of the spot image of the infrared light on the light receiving element.

The distance signal output from the arithmetic unit 6 is converted into a digital signal by the analog/digital converter 7, and then sent to the mixer 1.
Supplied with 4 and 15 elegance and so on.

The mixer 14 mixes a and b at a ratio of a+*b, where k is the mixing ratio, a is the output value of the preamplifier 13, and b is the output value of the preamplifier 12. The mixing ratio at this time is
As the distance signal indicates from a long distance to a short distance, k=- based on the output signal of the analog/digital converter 7.
Takes the value from 1 to =o.

The equal elegance 15 changes the frequency characteristics based on the output signal of the analog/digital converter 7 so that the overall frequency characteristics of the microphone become flat in accordance with the value of the mixing ratio.

FIG. 2 is a directional characteristic diagram of the microphone.

The 10 unidirectional microphones A and the 1) unidirectional microphone B are arranged at an interval of d (d=λ/2). At this time, the phase of the sound coming from the front of the microphones is opposite to that of the two microphones, and the phase of the sound coming from the side direction is the same.

The outputs of the two microphones 10.1) are connected to a preamplifier 12
．． After being amplified in 13, they are mixed in a mixer 14 at a ratio of k. However, if the copying object is located far away, the mixing ratio of the two output signals is k = -1, and the directivity of the microphone is The characteristics are unidirectional with a secondary sound pressure gradient shown in Figure 2 (di, (e), ([1). At this time, the frequency characteristics of the microphone are 6 dB10
Since the frequency characteristics of the E-elegant 15 shift toward the low range side at c and t, the low range is lifted.

Furthermore, when the subject is located at a short distance, the mixing ratio is k=o, and only the output of the microphone AIO is output from the mixer 14, and the directional characteristic of the microphone is
As shown in Figures (a), (b), and (C), it has first-order unidirectionality. At this time, since the frequency characteristics of the microphone are flat, the frequency characteristics of the equal grace 15 are also flat.

If the subject is located at a medium distance, the mixing ratio will be - based on the output signal of the analog/digital converter 7.
Values of 1<k<Q are selected and the values shown in Fig. 2 (al, fbl,
(cl and fd), (1) 41, ([Has a directivity characteristic intermediate between 1.

Also, as the shooting zoom lens changes from the wide-angle side to the telephoto side, based on the output signal of the zoom position encoder 9,
The gain of the variable amplifier 16 is increased to obtain the directional characteristics shown in FIG. 2, and the volume of the microphone is increased.

That is, by controlling the mixing ratio of the mixer 14 and the frequency characteristics of the equal-elegant 15 using the output signal of the distance measuring device 17, and controlling the gain of the variable amplifier 16 using the output signal of the zoom position encoder 9, the distance and distance of the subject can be adjusted. The overall directional characteristics and volume of the microphone are controlled based on the wide-angle and telephoto information of the zoom lens.

As described above, according to the present invention, based on the output signal of the distance measuring device 17, in the case of a subject located far away, the directivity of the variable directional microphone is made narrow, and noise around the sound source is reduced. In the case of a subject located at a close distance, the variable directional microphone can be set to wide directivity, allowing surrounding sounds to be taken in as well.

In addition, as the focal length of the shooting zoom lens changes from the wide-angle side to the telephoto side, the volume of the variable directional microphone is increased based on the output of the zoom position encoder 9, which changes the effect that the sound image approaches along with the image. This allows for a natural-feeling sound collection.

The distance measuring device 17 used here can be the one used in the automatic focus adjustment device of a video camera, so the above configuration can be achieved by simply adding one microphone and a simple circuit. can do.

Effects of the Invention The present invention uses the output signals of the distance measuring device and the zoom position encoder as control signals to change the directivity and volume of the microphone, and collects natural sound according to the distance of the sound source and the zooming state. This provides a microphone with new effects.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the video camera of the present invention, FIG. 2 is a directional characteristic diagram of a microphone of the video camera of the present invention, and FIG. 3 is a configuration diagram of a microphone of a conventional video camera. FIG. 4 is a directional characteristic diagram of a conventional video camera microphone. 8... Shooting zoom lens, 9... Zoom position encoder, 10... Microphone AS
1)...Microphone B, 12.13...
...Preamplifier, 14...Mixer, 15...
...Elegance, 16...Variable amplifier, 17...
... Distance measuring device. Name of agent: Patent attorney Toshio Nakao 1 name 3 - 1) - Microphone 8 17 - Distance measuring device Fig. 3 1b Fig. 4

Claims (2)

[Claims] (1) It has a variable directional microphone that mixes the output from at least two microphones to vary the directivity, and a distance measuring device that outputs a signal corresponding to the distance to the subject, and corresponds to the distance to the subject. A video camera comprising a mechanism for changing the directivity of a variable directional microphone depending on a signal. (2) It has a zoom position encoder that outputs a focal length signal of a photographing zoom lens, and is equipped with a mechanism that changes the volume of a microphone based on the output of the zoom position encoder. ) Video camera described in section 2.