JPH055726Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" This invention relates to an audio level display circuit, particularly to an audio level display mechanism for a viewfinder of a video camera.

``Prior art and its problems'' Professional video cameras are designed to monitor audio output from a microphone or audio input from a VTR. To monitor the input or output audio level of this type of conventional video camera, use earphones or a headphone to check directly with your ears (VTR).
There is a method of checking using a level meter on the device.There is a method of checking using a level display device other than the CRT screen of the electronic viewfinder (for example, a level display device using LEDs, etc.). However, with the above method, it is difficult to accurately check and adjust the audio level, and the above method does not work when the VTR device is set to a specific state (recording state, recording standby state, or playback state). only,
Although monitoring is possible, in other situations it is difficult to monitor the volume of the input or output to the video camera or adjust the volume based on it. Furthermore, the above method requires a separate display device such as an LED in addition to the CRT display device, which has disadvantages in terms of space and cost.

For reference, a technical technique for displaying the level of a video signal on the screen of a television camera monitor is disclosed, for example, in Japanese Patent Application Laid-Open No. 159178/1982, but it is not covered by the present invention. The problem to be solved is different from that of monitoring the audio output of a video camera, and as is clear from the solution described below, such a monitor of the level of a video signal cannot be applied to the present invention.

``Purpose of the invention'' This invention was proposed in view of the above-mentioned conventional circumstances, and is capable of accurately monitoring the volume under any conditions, does not require special installation space, and is inexpensive. The object of the present invention is, of course, to provide an audio level display device that can always display the effective value of an audio signal, and also to make the display digital and easy to quantitatively judge.

"Means for achieving the purpose" In order to achieve the above purpose, this invention adopts the following means. That is, as an audio level display mechanism in an analog video camera, an effective value rectifier circuit that rectifies an audio input signal,
The output of the effective value rectifier circuit is converted into a digital signal.
The system is provided with A/D conversion means consisting of an A/D converter having the function of sampling and holding peak values as required, a microcomputer which operates based on the output of the A/D conversion means, graphic signal generation means consisting of a CRT controller which outputs a graphic signal for displaying a character according to the input level in accordance with instructions from the microcomputer, and a mixing circuit which mixes the output of the graphic signal generation means with a video signal and inputs the result to an electronic viewfinder.

Therefore, in particular, the microcomputer can take in the A/D converted data of the audio signal through the effective value rectifier circuit, convert it into graphic data, and display it on the electronic viewfinder.
Effective values can be displayed at all times.

Moreover, since the displayed value is digital, it is possible to determine the appropriate amount.

Furthermore, since the peak of A/D converted data can be held, level adjustment is easy.

"Embodiment" FIG. 1 shows an embodiment of this invention.

When the input audio signal is obtained from a microphone 1 attached to a video camera, the output from the microphone 1 is amplified by an amplifier 2 and then input to an A/D conversion means 10. Also,
If the input audio signal is a return signal from a VTR, it is input to the A/D conversion means 10 as is.

A selection switch 3 allows selection of which of the above two signals is input to the A/D conversion means.

As is well known, the A/D conversion means 10 rectifies the analog input signal using an effective value rectification circuit 11.
The rectified signal is A/D converted by an A/D converter 12. In this case, by using the A/D converter 12 with a peak hold function,
It is preferable that the peak value can be displayed as described below, and that the selection switch 13 can be used to select whether or not to use this function. For level meters used in audio equipment
Since the IC is an A/D converter having the above function, it is preferable to use this as the A/D converter 12. However, in this case, like audio equipment,
Since it does not drive LEDs, etc., it is okay to design the current consumption to be smaller.

A digital signal corresponding to the magnitude of the input signal obtained from the A/D converter 12 is input to a graphic signal generating means 20, where a graphic signal necessary for display on the electronic viewfinder 40 described below is generated. That is, the digital signal obtained from the A/D converter 12 is input to the microcomputer 21 for controlling the CRT controller 22 (hereinafter referred to as CRTC), where it is converted into the signals necessary to control the CRTC 22. converted. CRTC22 is the microcomputer 2 mentioned above.
According to the command from 1, it outputs an analog graphic signal of the character corresponding to the input.

The graphic signal thus obtained is mixed with the video output in the mix circuit 30 and displayed on the CRT 41 of the electronic viewfinder 40.

Figure 2 shows CRT4 of electronic viewfinder 40.
This is an example of the audio level display in 1. The number of rectangular sections 42 corresponds to the magnitude of the input audio level...
42 is displayed in a specific color.
Of course, this rectangular section may be a round section, or the length of the rod-shaped body may change depending on the input, and the microcomputer 2 determines which character to display.
1 and CRTC22.

Furthermore, it is preferable to provide a switch 23 for operating the microcomputer 23 so that it is possible to select whether or not to display the volume level.

Note that the microcomputer 21 and CRTC 22 are conventionally provided in video cameras for displaying characters, etc., so it is preferable to use them.

FIG. 3 shows an example of level display in relation to time when the A/D converter 12 is provided with a peak hold function. Peak value of input level P
is retained even if the input becomes small.
It is displayed on the first screen and provides convenience for adjusting the volume.

``Effects of the invention'' As explained above, this invention allows accurate input audio levels to be confirmed regardless of the operating status of the VTR device without the need for special display devices such as LEDs in the viewfinder. However, it is effective to make the adjustment properly.
In particular, it has the unique effect of continuously displaying the effective value for the audio signal, that the displayed value is digital and easy to judge, and that it is easy to adjust the level.

[Brief explanation of the drawing]

Figure 1 is a block circuit diagram showing an embodiment of this invention, Figure 2 is a diagram of audio level display on a CRT,
FIG. 3 is an explanatory diagram showing an example of peak hold display. In the figure, 10... A/D conversion means, 11... Effective value rectification circuit, 12... A/D converter, 20... Graphic signal generation means, 21... Microcomputer, 22... CRTC, 30... ...mix circuit, 40...view finder.

Claims (1)

[Claims for Utility Model Registration] A that has an effective value rectifier circuit that rectifies an analog audio input signal, converts the output of the effective value rectifier circuit into digital, and has a function of sampling and holding peak values as necessary. A/D converter comprising an A/D converter; a microcomputer that operates based on the output of the A/D converter; Output graphic signal
An audio level display mechanism in a video camera consisting of a graphic signal generating means comprising a CRT controller, a mixing circuit for mixing the output of the graphic signal generating means and a video signal and inputting the mixture to an electronic viewfinder; .