JPH0250692A - Video camera - Google Patents

Abstract

PURPOSE:To allow the operator to engage in the photographic operation without any care by providing a shutter speed control means detecting fluorescent light flicker included in color temperature information of an object required for white balance adjustment and bringing the shutter speed of an image pickup element to a speed not subject to the effect of fluorescent light flicker. CONSTITUTION:A flicker detection circuit 22 is provided between a color temperature detection circuit 11 and a shutter speed changeover circuit 15 and when a light source is a fluorescent light or a light source includes a fluorescent light, an output of the flicker detection circuit 22 brings the shutter speed into a speed not subject to the effect of the fluorescent light flicker. Thus, if a photographer enters a room lighted by the fluorescent light lighting from an outdoor place while picking up an object at the standard shutter speed, since the changeover to the high speed shutter not subject to the effect of fluorescent light flicker is implemented automatically, the photographer can engage in the photographic operation such as setting of camera angle or zooming without any care.

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Field of Industrial Application The present invention relates to a video camera with measures against fluorescent lamp flicker.

[Prior Art] A video camera 1 shown in FIG. 2 focuses light from a subject that has passed through an imaging lens system consisting of a focus lens 2 and a zoom lens 3 onto a solid-state imaging device 5 via an optical filter 4. Take a configuration that allows The image information accumulated in the solid-state imaging element 5, which has a plurality of pixels arranged in a two-dimensional array, is sequentially read out, for example, for each field by vertical and horizontal scanning, and is supplied to the brightness/color separation circuit 6 to generate a brightness signal. and color signals. The separated luminance signal is supplied to the encoding circuit 8 via the luminance signal processing circuit 7, and the chrominance signal is supplied to the encoding circuit 8 via the chrominance signal processing circuit 9 and the white balance adjustment circuit 10.

The white balance adjustment circuit 10 is for reproducing a white object as white by adjusting the gain of the red signal and the blue signal according to the color temperature of the object which changes depending on the light from the light source, and is a color temperature detection circuit. It operates by the output of 11. A solid-state image sensor 12 with an optical filter is connected to the color temperature detection circuit II, and the light passes through a milky-white diffusion filter 13 placed on the curved side of the solid-state image sensor 12. This light provides color temperature information. That is, red (R), blue (B), green CG) separated by the optical filter attached to the front surface of the solid-state image sensor I2.
The color components of the three primary colors are supplied to a color temperature detection circuit l],
There, the color component ratios are converted to R/G and B/G with green as the reference. And these color component ratios R/G, B/G are:
It is sent to the aforementioned white balance adjustment circuit IO as a command to express the color component ratio of the light source and vary the level of each red and blue color signal, and is used for white balance adjustment.

In the case of this example, the readout speed of the charges accumulated in the solid-state image sensor 5, that is, the shutter speed, can be manually switched in four stages by the shutter speed switching circuit 15 connected to the drive circuit 14 of the solid-state image sensor 5. It has become. That is, the solid-state image sensor 5 has a standard shutter speed of 1760 seconds and 1/+00. I/250.1/100
A total of four shutter speeds of 0 seconds are available, and by operating a slide-type changeover switch 16 connected to a shutter speed changeover circuit 15, the shutter speed can be selected in accordance with the movement of the subject.

[Problems to be Solved by the Invention] The above-mentioned conventional video camera has a variable gloss speed, so when capturing an image of a subject moving at high speed, by selecting a shutter speed that matches the movement of the subject, it is possible to obtain clear images with less afterimage. It has the advantage of being able to capture accurate images. In addition to this, for example, when capturing an image under indoor fluorescent lighting, switching the shutter speed to a shutter speed of 1/100 seconds or less may cause the fluorescent lights to flicker at the commercial power frequency, resulting in the image being captured. The flickering that occurs, so-called fluorescent lamp flicker, can be avoided.

However, the above-mentioned glossy speed switching is done manually, so if you go from shooting outdoors at the standard glossy speed to indoor shooting under fluorescent lighting while following a subject, you may have to change the camera angle setting or zoom. Because they were so focused on the imaging task, such as operating the camera, they did not realize that they needed to change the shutter speed, resulting in the problem of being easily affected by fluorescent light flicker.

[Means for Solving the Problems] The present invention has solved the above problems, and includes an image sensor with variable shutter speed, a color temperature detection circuit that obtains color temperature information of a subject necessary for white balance adjustment, A shutter speed control means for detecting fluorescent lamp flicker included in the color temperature information detected by the color temperature detection circuit and adjusting the gloss speed of the image sensor to a speed that is not affected by the fluorescent lamp flicker. This is a characteristic feature.

[Function] This invention detects fluorescent lamp flicker included in the color temperature information of the subject necessary for white balance adjustment, and automatically adjusts the gloss speed of the image sensor to a speed that is not affected by fluorescent lamp flicker. to avoid fluorescent light flicker.

[Example] Hereinafter, an example of the present invention will be described with reference to FIG. 1. FIG. 1 is a circuit diagram showing an embodiment of a video camera according to the present invention.

In FIG. 1, the video camera 21 is provided with a flicker detection circuit 22 between the color temperature detection circuit 11 and the shutter speed switching circuit 15, and has a flicker detection circuit 22 installed between the color temperature detection circuit 11 and the shutter speed switching circuit 15. In this case, the output of the flicker detection circuit 22 is used to set the shutter speed to a speed that is not affected by fluorescent lamp flicker. The flicker detection circuit 22 waves the commercial power frequency component included in the color temperature information sent from the solid-state image sensor 12 to generate a flicker detection signal, and the flicker speed switching circuit 1
5 constitutes a shutter speed control means.

That is, the glossy speed switching circuit 15 that receives the flicker detection signal switches the shutter speed to 1/100 seconds if the shutter speed at that time is the standard shutter speed, and also switches the shutter speed to 1/100 seconds or less at a glossy speed of 1/100 seconds or less. If so, the shutter speed at that point is continued. Therefore, for example, if you enter a room under fluorescent lighting from outdoors while shooting at a standard shutter speed, the photographer will automatically switch to a high-speed glossy mode that is not affected by fluorescent flicker. This allows you to concentrate on imaging tasks such as setting the camera angle and zooming with peace of mind, and avoids the inconvenience of being affected by fluorescent light flicker due to neglecting to switch the shutter speed.

[Effects of the Invention] As explained above, the present invention detects fluorescent lamp flicker included in the color temperature information of the subject necessary for white balance adjustment, and adjusts the shutter speed of the image sensor so that it is not affected by fluorescent lamp flicker. Since we have provided a shutter speed control means, you can enter a room under fluorescent lighting from outside while taking pictures at the standard shutter speed, or you will not notice that you are using the standard shutter speed even though you are under fluorescent lighting. In such cases, the shutter speed control means automatically switches the glossy speed to a speed that is not affected by fluorescent lamp flicker, which is included in the color temperature information of the light source necessary for white balance adjustment. This provides excellent effects such as allowing you to concentrate on your imaging work with peace of mind.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of a video camera of the present invention, and FIG. 2 is a circuit diagram showing an example of a conventional video camera. 5. , Solid-state image sensor, Il, , Color temperature detection circuit, 1
2. , solid-state image sensor, +3. ,,diffusion filter, 14
．． ,,drive circuit,15. ,,Glossy speed switching circuit, 16. ,, changeover switch, 2+,, video camera, 22. , flicker detection circuit.

Claims (1)

[Claims] An image sensor with a variable shutter speed, a color temperature detection circuit that obtains the color temperature information of the subject necessary for white balance adjustment, and a fluorescent lamp flicker included in the color temperature information detected by this color temperature detection circuit, which detects the A video camera comprising a shutter speed control means for controlling the shutter speed of an image sensor to a speed that is not affected by fluorescent lamp flicker.