JP2000278581A - Video camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an excellent characteristic and a sense of unity in image and sound through zooming to a small sized video camera by solving problems of methods to change directivity of a zoom microphone applied to various electric device and adopting a method where a sound volume and a frequency characteristic of one microphone are changed in matching with a change in a zoom magnification. SOLUTION: A filter 14 cuts low frequency components of an output signal of a 1st amplifier circuit 13 and a 2nd amplifier circuit 15 amplifies an output of the filter 14. An electronic volume 16 receives an output signal of the 2nd amplifier circuit 15. A control signal voltage generating circuit 17 allows the electronic volume 16 to control the reception of the output signal from the 2nd amplifier circuit 15 in response to a zoom ratio through a zoom operation and an adder 18 sums an output signal from the electronic volume and the output signal from the 1st amplifier circuit 13 and provides an output of the sum, which provides a sense of unity between video and audio data.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a zoom microphone mounted on a camera having a function of zooming an image and picking up a zoom sound in synchronism with the image, and a video camera including the same.

[0002]

2. Description of the Related Art In recent years, consumer video cameras have become remarkably popular. While most of these consumer video cameras have a zoom function, these built-in microphones have a fixed directivity, and therefore have a poor sense of unity between video and audio.

[0003] A video camera provided with a conventional microphone will be described below.

Conventionally, a video camera is disclosed in Japanese Patent Laid-Open No. 1-3217.
The one described in Japanese Patent Publication No. 80 is known. The video camera is shown in FIG. FIG. 3 shows a block diagram of a conventional video camera. In FIG. 3, reference numeral 1 denotes an imaging unit having a zoom function and capable of capturing an image of a subject. 2
Is a first microphone with wide directivity used at the time of wide-angle shooting, and is also called an omnidirectional microphone. 3
Is a second microphone having a narrow directivity used at the time of telephoto shooting, and is also called a unidirectional microphone.
Reference numeral 4 denotes a mixer for changing the audio output signal levels of the first and second microphones 2 and 3. Ra and Rb are mixers 4
It is a variable resistor provided inside. Reference numeral 5 denotes a control signal voltage generation circuit that generates a control signal according to the zooming operation of the imaging unit 1 and controls the mixer 4. 6
Is an audio recording circuit.

The operation of the conventional video camera configured as described above will be described below.

First, a zoom operation causes a zoom position information signal from the imaging section 1 to be transmitted to a control signal voltage generation circuit 5.
And controls the variable resistors Ra and Rb of the mixer 4 at a zoom ratio corresponding to the zoom position.

For example, when the image pickup section 1 is performing wide-angle photographing, the control signal voltage generation circuit 5 controls to increase the resistance value of the variable resistor Rb of the mixer 4 so as to obtain a narrow directivity at the time of telephoto photographing. The variable resistor Ra of the mixer 4 is controlled so that the sound output signal of the second microphone 3 is attenuated and only the sound output signal of the first microphone 2 having a wide directivity is output to the sound recording circuit 6.

When the image pickup section 1 is performing telephoto shooting, the control signal voltage generation circuit 5 controls to increase the resistance value of the variable resistor Ra of the mixer 4, and outputs the audio output signal of the first microphone 2. And the variable resistor Rb of the mixer 4 is controlled so that only the audio output signal of the second microphone 3 is output to the audio recording circuit 6.

The audio signal controlled as described above is input to the audio recording circuit 6, and the audio signal is recorded on a recording medium or the like.

FIG. 4 shows a change in directivity of an audio signal input to the audio recording circuit 6 in which the variable resistors Ra and Rb of the mixer 4 are controlled at a zoom ratio corresponding to a zoom position.

[0011]

However, in the above-described conventional configuration, a plurality of microphone units having different directivities are required, so that the video camera cannot be downsized and the cost is increased. Had.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a video camera capable of realizing a reduction in size and cost of the video camera.

[0013]

In order to achieve the above object, a video camera according to the present invention comprises an imaging means capable of performing a zoom operation, and controls a sound signal in accordance with the zoom operation of the imaging means. A microphone for picking up sound, a first filter for reducing a low frequency of an audio output signal from the microphone, and a second filter for extracting only a high frequency of the audio output signal from the first filter. A level varying unit that varies a level of an audio output signal from the second filter; a control unit that controls a level of the level varying unit in accordance with a zoom operation in the imaging unit; Adding means for adding the output audio signal of the level varying means.

With this configuration, the video camera can be downsized by changing the gain and frequency characteristics of the audio output signal of the microphone unit without changing the directivity.
A video camera can be provided at a low price.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claims 1 and 2 of the present invention is a video camera comprising an imaging means capable of performing a zoom operation and controlling an audio signal in accordance with the zoom operation of the imaging means. A microphone that picks up sound, a first filter that reduces a low frequency of an audio output signal from the microphone, and a second filter that extracts only a high frequency of the audio output signal from the first filter, Level varying means for varying the level of the audio output signal from the second filter; control means for controlling the level of the level varying means in accordance with a zoom operation in the imaging means;
And an adding means for adding the output audio signal of the level varying means. With this configuration, when video and audio are recorded, audio and video signals are recorded in accordance with a change in the zoom magnification of the lens. Output level and frequency characteristics change. This change is based on changes in human vision and hearing when played back, and as a result, when played back, the volume and ambient sound of the subject change according to the zoom of the image, and the directivity does not change. However, it has the effect that a sufficient sense of unity of video and audio can be obtained.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a block diagram of a video camera according to an embodiment of the present invention.
11 is an omnidirectional microphone, 12 is a microphone 1
In the present embodiment, a first filter that cuts the low band of the audio output signal from No. 1 and has a characteristic that a drop of 3 dB becomes 200 Hz is used. Reference numeral 13 denotes a first amplifier circuit that amplifies the audio output signal from the first filter 12, 1
Reference numeral 4 denotes a second filter that cuts a low band of the audio output signal from the first amplifier circuit 13 and extracts only a high band. In the present embodiment, a filter having a characteristic that a 3 dB drop is 600 Hz is used. . Reference numeral 15 denotes a second amplifier circuit for amplifying the audio output signal from the second filter 14, reference numeral 16 denotes an electronic volume which is a level variable means for changing the level of the audio output signal from the second amplifier circuit 15, and reference numeral 17 denotes an imaging unit. A control signal voltage generation circuit which is a control means for generating a control signal in accordance with the zooming operation of the electronic volume 16 and controlling the electronic volume 16 by controlling the output level of the electronic volume 16 to be small when the imaging unit 19 is in the wide-angle shooting state When the imaging unit 19 is in the telephoto shooting state, the electronic volume 1
6 to increase the output level. 18
Is an adder which is an adding means for adding an audio output signal from the first amplifier circuit 13 and an audio output signal from the electronic volume 16, and 19 is an image pickup section which is an image pickup means for photographing a subject image. Telephoto shooting for enlarging an image and wide-angle shooting for reducing an image can be performed, and the size of the image between the telephoto end and the wide-angle end can be changed to a desired size.
Reference numeral 20 denotes an audio recording circuit that records the audio signal from the adding unit 18 on a recording medium such as a magnetic tape.

FIG. 2 shows an electronic volume 16 according to this embodiment.
FIG. 4 is a characteristic diagram showing a level of an output audio signal corresponding to a frequency characteristic of an input audio signal in FIG. 3, showing an output level at the time of photographing at a telephoto end and an output level at the time of photography at a wide-angle end. At frequencies up to about 10 kHz, the output level changes according to the zoom magnification.

The operation of the video camera thus configured according to the present embodiment will be described with reference to FIG.

First, the low band of the audio output signal from the omnidirectional microphone 11 is cut by a first filter 12 having a characteristic that a drop of 3 dB is 200 Hz.
This audio output signal is amplified by the amplifier circuit 13 of FIG. This audio output signal is called for wide-angle shooting. The low-frequency range of the audio output signal for wide-angle shooting is further cut by a second filter 14 having a characteristic of dropping 3 dB to 600 Hz.
The second amplifier circuit 15 amplifies the audio output signal by 12 dB. This audio output signal is called for telephoto shooting. An audio output signal for telephoto shooting is input to the electronic volume 16.

By the zoom operation in the image pickup section 19, the control signal voltage generation circuit 17 reads the zoom position information signal from the image pickup section 19, and controls the electronic volume 16 according to the zoom ratio. For example, at the time of wide-angle shooting, control is performed so that the level at the electronic volume 16 is reduced so that the audio output signal of the second amplifier circuit 15 is attenuated as approaching the wide-angle end, and the level at the wide-angle end is minimized. I do. On the other hand, during telephoto shooting,
The level in the electronic volume 16 is controlled to increase as the telephoto end is approached so that the audio output signal of the second amplifier circuit 15 is passed, and the level at the telephoto end is controlled to be the highest. The level control of the output audio signal from the electronic volume 16 is clearly shown in the characteristic diagram of FIG.

Then, the audio output signal for wide-angle photography from the first amplifier circuit 13 and the audio output signal of the electronic volume 16 are added by the adder 18, and only the audio output signal for wide-angle photography is obtained during wide-angle photography. At the time of telephoto shooting, the audio output signal for wide-angle shooting and the audio output signal for telephoto shooting are added and input to the audio recording circuit 20.

As described above, according to the present embodiment, the audio output signal for telephoto shooting is increased by 12 dB with respect to the audio output signal for wide-angle shooting, and the first amplifier for wide-angle shooting is increased. The second filter 14 for telephoto shooting has a characteristic of cutting the low frequency range further than the filter 12, and the electronic volume 16 controls the audio signal for telephoto shooting, and the adder 1
2, the sensitivity and frequency characteristics in the middle and high frequency ranges are increased in telephoto shooting as compared to wide-angle shooting as shown in the frequency characteristics in FIG. 2, and when the zoom is operated in telephoto shooting, the sense of clarity with respect to ambient noise is improved. The effect of zooming up the audio is obtained. That is, the volume and the surrounding sound of the subject change in accordance with the zoom of the image, and a sufficient sense of unity between the image and the sound can be obtained without changing the directivity.

[0024]

As described above, according to the present invention, the sound volume and the sound level can be adjusted in accordance with the zoom of the image by the method of changing the audio output level and the frequency characteristic in accordance with the change in the zoom magnification of the lens with one microphone unit. An excellent effect is obtained in that the ambient sound of the subject changes and a sufficient sense of unity of the video and audio is obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of a video camera according to an embodiment of the present invention.

FIG. 2 is a frequency characteristic diagram for explaining the operation of the video camera according to the first embodiment;

FIG. 3 is a block diagram of a conventional video camera.

FIG. 4 is a directivity change diagram for explaining the operation of a conventional video camera.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Non-directional microphone 12 1st filter 13 1st amplifier circuit 14 2nd filter 15 2nd amplifier circuit 16 Electronic volume 17 Control signal voltage generation circuit 18 Adder 19 Imaging part

Claims (2)

[Claims] 1. A video camera that includes an imaging unit capable of performing a zoom operation, and controls an audio signal in accordance with the zoom operation of the imaging unit, comprising: a microphone that collects audio; and a microphone that outputs an audio output signal from the microphone. A first filter for reducing a low band, a second filter for extracting only a high band of an audio output signal from the first filter, and a level for varying a level of the audio output signal from the second filter. Variable means, control means for controlling the level of the level variable means in accordance with a zoom operation in the imaging means, and adding means for adding the first filter and the output audio signal of the level variable means. A video camera characterized by the following. 2. A video camera comprising an imaging unit capable of performing a zoom operation and controlling an audio signal in accordance with the zoom operation of the imaging unit, comprising: a microphone that collects audio, and an audio output signal from the microphone. A first filter for reducing a low band, a second filter for extracting only a high band of an audio output signal from the first filter, and a level for varying a level of the audio output signal from the second filter. Variable means, control means for controlling the level of the level variable means in accordance with a zoom operation in the imaging means, and adding means for adding the first filter and the output audio signal of the level variable means, The control unit controls the output level of the level varying unit to be small when the imaging unit is in the wide-angle shooting state, and when the imaging unit is in the telephoto shooting state. A video camera, wherein control is performed to increase an output level in the level varying means.