Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JPH07336793 [0001] FIELD OF THE INVENTION The present invention relates to microphones used for video cameras. [0002] 2. Description of the Related Art In recent years, video cameras have become smaller, lighter and lower in price, and are widely used in many homes, and their applications are also expanding in various fields. Along with this, there is a change from a tendency to emphasize only video recording to a tendency to also emphasize sound information recording, and it is desirable that the user can experience a sense of presence at the time of reproduction more than at the time of reproduction. Hereinafter, a conventional video camera microphone will be described with reference to the drawings. [0003] FIG. 4 is a block diagram of a conventional microphone for a video camera. 1 is an angle of view detection means, 3 is a stereo sound pickup means, 4 is an acoustic zoom control means, and 5 is an acoustic signal recording means. 10 is a superdirective sound collecting unit, 11 is a stereo sound collecting unit. 10-05-2019 1 [0004] In the above configuration, when recording of a video camera is started, an audio signal is input to the stereo sound collecting means 3. For example, the stereo sound pickup means 3 may be configured by a superdirective sound pickup unit 10 and a stereo sound pickup unit 11 as shown in the figure. In this case, the superdirective sound pickup unit 10 is composed of two single directional microphone units, and the directivity pattern changes in a low frequency range and a high frequency range, and an input with reduced wind noise and mechanical vibration noise A signal is output to the acoustic zoom control means 4. On the other hand, in the stereo sound pickup unit 11, two single directional microphone units are configured such that the main axes of their directivity are at an angle of 90 °, and the input signal is an acoustic zoom control as a left and right two channel signal It is outputted to the means 4. The angle of view detection means 1 detects the zoom position in synchronization with the operation of the optical zoom lens, and outputs a zoom position signal to the acoustic zoom control means 4. The acoustic zoom control means 4 controls the output signal levels of the superdirectivity sound pickup unit and the stereo sound pickup unit which are output signals of the stereo sound pickup means 3 according to the zoom position signal from the angle of view detection means 1. The respective signals are then added and output to the acoustic signal recording means 5 as stereo signals of two channels. The acoustic signal recording means 5 records the output signal. [0005] In this way, sound is collected by superdirectivity at the time of telephoto, and stereo sound collection is performed synchronously with the zoom of the image at the wide angle, and integration of the image and sound is realized. [0006] In such a conventional microphone for a video camera, the acoustic zoom control means 4 uses the zoom position signal from the angle of view detection means 1 to output the output signal level of the stereo sound pickup means 3. In the case of control, that is, in the case of controlling the system sensitivity, the increase / decrease level is constant regardless of the frequency. However, since the sensitivity is different between the high frequency component and the low frequency component for the same level change, there is a problem that the reproduced timbre is different depending on the control result of the level. 10-05-2019 2 [0007] The present invention solves the above-mentioned problems, and is for a video camera which realizes the zoom of a sound image with a constant tone regardless of the change in the output signal level of the stereo sound pickup means accompanying the change in zoom magnification of the optical lens in the acoustic zoom control means. The purpose is to realize a microphone. [0008] In order to achieve the above object, the present invention provides an angle of view detection means 1 for detecting a zoom position signal of an optical lens, and a stereo sound pickup means 3 for collecting an audio signal in stereo. Acoustic zoom control means 6 for controlling the level of the output signal from the stereo sound pickup means 3 in accordance with the loudness curve for each frequency as a function of the zoom position signal outputted from the angle of view detection means 1; And an acoustic signal recording means 5 for recording the stereo signal output from the above. [0009] According to the present invention, according to the above configuration, by adding the audio signal level control associated with the zoom position signal of the optical lens in accordance with the loudness curve for each frequency, the zoom effect of the image can be obtained without changing the timbre of the recorded sound. And get a sense of sound zoom effect. [0010] Embodiments of the present invention will be described hereinbelow with reference to the drawings. FIG. 1 is a block diagram of a video camera microphone according to a first embodiment of the present invention. In the figure, the same components as those of the conventional example shown in FIG. What differs from the conventional example is the internal configuration of the acoustic zoom 10-05-2019 3 control means 6. 61 is a filter coefficient storage unit, 62 is a convolution operation unit, and 63 is a signal addition unit. [0011] The operation of the above arrangement will be described. First, when recording of a video camera is started, an audio signal is input to the stereo sound collecting means 3. The process until the output signal from the stereo sound pickup means 3 is input to the acoustic zoom control means 6 is the same as in the prior art. The angle of view detection means 1 detects the zoom position in synchronization with the operation of the optical zoom lens, and outputs the zoom position signal to the acoustic zoom control means 6 as in the prior art. [0012] The acoustic zoom control means 6 performs the following operation. In the acoustic zoom control means 6, with the zoom position signal value as a memory address, filter coefficients for realizing the loudness curve corresponding to each control level are stored in advance in the filter coefficient storage unit 61. The filter coefficient is input from the filter coefficient storage unit 61 to the convolution operation unit 62 based on the zoom position signal value input from the angle of view detection unit 1. Further, the output signal from the stereo sound pickup means 3 is inputted to the acoustic zoom control means 6, inputted to the convolution operation unit 62, and the convolution operation is performed. As a result, the signal addition unit 63 adds the signals at the mixing ratio determined by the zoom position signal value, and outputs the result to the acoustic signal recording means 5 as a stereo signal of two channels. The acoustic signal recording means 5 records the output signal. [0013] As described above, by controlling the sound signal level control according to the zoom position signal of the optical lens in accordance with the loudness curve for each frequency, the zoom effect of the image and the zoom effect of the audio can be maintained while maintaining the timbre of the reproduced sound. You can get a sense of experience. [0014] 10-05-2019 4 Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 2 shows a block diagram of a microphone for a video camera in the second embodiment of the present invention. The angle of view detection means 1, the stereo sound collection means 3, and the acoustic signal recording means 5 are the same as in the first embodiment. What differs from the first embodiment is the internal configuration of the acoustic signal control means 7. [0015] The sound signal control means 7 changes the characteristics of the input signal from the stereo sound collecting means 3 so as to change the spatial impression in response to the zoom position signal from the angle of view detection means 1. For example, when control is performed to increase the sense of spread at the time of telephoto and decrease at the time of wide angle, the sound pressure frequency characteristics in which the frequency band correlating to the sense of spread is changed stepwise corresponds to the zoom position signal. Then, the filter coefficient is determined by inverse Fourier transform, and the zoom position signal is stored in the expansion feeling filter coefficient storage unit 71 with the memory address. A band that is particularly correlated with the sense of spread is 320 Hz in the 1/3 octave band. In the acoustic signal control means 7, the filter coefficients at the memory address corresponding to the zoom position signal value inputted from the angle of view detection means 1 are taken out from the spread feeling filter coefficient storage unit 71 and set in the convolution operation unit 72. The signal from the stereo sound pickup means 3 is converted by the convolution operation unit 72 by the convolution operation. The converted signals are added as in the first embodiment and stored in the acoustic signal recording means 5. [0016] As described above, by converting the characteristics of the acoustic signal by coupling to the zoom magnification and recording the signal to which the sense of spread is added, the sense of spread is large in the case of long distance at the time of reproduction, and in the case of proximity. It is possible to realize the sound more in the image, such as narrowing the width of the sound image. [0017] 10-05-2019 5 Next, a third embodiment of the present invention will be described with reference to the drawings. FIG. 3 shows a block diagram of a microphone for a video camera in the third embodiment of the present invention. The angle of view detection means 1, the stereo sound collection means 3, and the acoustic signal recording means 5 are the same as in the first embodiment. 9 is an elevation angle detection means, 8 is an acoustic signal control means. 81 is a filter coefficient storage unit, 82 is a convolution operation unit, and 83 is a signal addition unit. Here, the filter coefficients of the filter coefficient storage unit 81 are created as follows. [0018] By controlling the sound pressure frequency characteristics, the height of the sound image is changed. Therefore, the sound pressure frequency characteristic in which the level of the band correlated with the height of the sound image is changed is created with the number of steps of the height of the sound image to be controlled, and the filter coefficient is determined by the inverse Fourier transform. As a band correlated with the height of the sound image, bands of 200 Hz, 5 K to 10 KHz, and 16 KHz in the 1/3 octave band can be mentioned. [0019] The operation in the above configuration will be described. When recording is started, an audio signal is taken in by the stereo sound collecting means 3. Also, the target direction of the video camera is detected by the elevation angle detection means 9 every hour as an elevation angle from the horizontal plane, and is inputted to the acoustic signal control means 8 as an elevation angle signal. For example, a level may be incorporated as elevation angle detection means 9. In the acoustic signal control means 8, the filter coefficient is output from the filter coefficient storage unit 81 to the convolution operation unit 82 corresponding to the data information of the elevation signal, and is set as a filter. In the convolution unit 82, the input signal from the stereo sound pickup means 3 is convoluted with the filter. The filtered signal is added by the signal addition unit 83 at the mixing ratio determined by the zoom position signal value obtained by the angle of view detection means 1 and output to the acoustic signal recording means 5 as a stereo signal of two channels. . The acoustic signal recording means 5 records the output signal. [0020] 10-05-2019 6 As described above, by controlling the collected sound signal, it is possible to obtain a sound image corresponding to the movement of the video camera at the time of reproduction, and it is possible to realize the realism of the site. [0021] In the second embodiment, the frequency to be controlled is set to a specific value by focusing on the sense of expansion of the sound image, but other bands are controlled similarly by changing the data of the filter coefficient storage unit Also, the contour of the sound can be changed in conjunction with the zoom position signal. [0022] In the third embodiment, only the height of the sound image coupled to the elevation signal is controlled. However, the sense of reality may be further enhanced by combining with the sense of spread as in the second embodiment. [0023] As described above, according to the present invention, by controlling the sound signal level control associated with the zoom position signal of the optical lens in accordance with the loudness curve for each frequency, the zoom of the image is maintained while maintaining the timbre of the reproduced sound. It is possible to obtain a sense of unity between the effect and the zoom effect of audio. [0024] In addition, by converting the characteristics of the acoustic signal by coupling to the zoom ratio and recording the signal to which a sense of spread is added, the sense of spread is large in the case of long distance during reproduction, and the width of the sound image in the case of proximity. It is possible to realize the sound that was more in the image, such as [0025] Furthermore, by controlling the height of the sound image of the sound signal collected by the stereo sound collecting means in accordance with the change of the elevation signal obtained by the elevation detection means for detecting the target direction of the video camera, At the time of reproduction, a sound image corresponding to the movement of the video camera can be obtained, and a more realistic presence on the site can be realized. 10-05-2019 7
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