JPH0110054Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a blurring mechanism for a television lens, and more particularly to a blurring mechanism for a television lens that blurs and projects a subject image onto the imaging surface of a television camera to adjust white balance.

Conventionally, most color cameras used for broadcasting are three-tube type, and before they can be put into operation, a series of adjustment operations are required to ensure correct color reproduction when replacing the image pickup tube or during regular maintenance. It is said that

That is, in order to obtain correct color reproduction with a color camera, it is necessary to select an appropriate color temperature conversion filter and control the gain of the amplification system in accordance with the color temperature of illumination light or external light.

Such adjustment in the operation of a color camera is generally referred to as color balance adjustment, and conventionally, the above adjustment has been performed manually or automatically by imaging a reference white color.

However, it is often difficult to prepare a reference white color and calibrate the camera system at the shooting site or while the camera is in operation. For example, when shooting an outdoor sports broadcast in the evening, the color temperature of the outside light changes from moment to moment, and it is not practical to prepare a standard white color and make adjustments each time.

On the other hand, television cameras with built-in pattern projectors that have built-in patterns for the above-mentioned adjustment have also been put into practical use, but with this method, it is not possible to quickly and easily grasp the color temperature characteristics of the photographed light.
The color temperature of the light source for pattern projection cannot be easily adjusted, and the color reproducibility is not very good.

It has also been proposed to use a defo-focus lens system for white balance adjustment (Japanese Unexamined Patent Publication No. 123727/1973), but this method does not require a focus mechanism when the depth of focus is deep, such as on the wide side of a zoom lens. Even if you extend it far, you will not be able to obtain the necessary defocus, and if you set the zoom lens to the telephoto side, the depth of focus will be extremely shallow, so you may have to adjust the white balance by changing the lighting conditions while leaving the zoom lens at the telephoto side. If you make any adjustments, you will have to perform tedious focusing again after defocusing, which is not practical.

Therefore, even in a television camera equipped with a zoom lens, the present invention integrates external light using an optical means provided in the imaging lens system, without using the reference white color, and easily obtains color temperature information of the external light. To provide a blurring mechanism for a television lens which can be grasped quickly and accurately and facilitates color balance adjustment of a color camera.

This objective is achieved by inserting a convex lens into the space in the television lens during color balance adjustment.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an optical system in which the present invention is applied to a television lens with a built-in extender, and a subject image is formed on an imaging surface 4 via a zoom lens system 1, an aperture 2, and a relay lens system 3. Further, the imaging magnification on the imaging surface 4 is increased by inserting the extender 6 into the 3x relay lens. At this time, there are three imaging surfaces 4 for each of the R, G, and B channels, but in order to simplify the explanation, only one will be explained. However, it goes without saying that the insertion of the extender 6 does not cause the focus position to shift.

If a convex lens 5 is inserted in place of the extender 6, the focus position of the lens system will be on the imaging plane 4.
As a result, a blurred subject image is formed on the imaging surface 4.

When looking at the video signal from the imaging surface 4 in this state, it becomes a signal with high spatial frequency components removed.

FIG. 2 shows these signals in an open aperture state. FIGS. 2A and 2B show each video signal A before the convex lens 5 is inserted, and each video signal B after inserting the convex lens 5, respectively. Furthermore, FIG. 3 shows a state in which the aperture is set to F4. Figure 3 A and B are convex lenses 5
Each video signal A before and after insertion of video signal B are shown respectively. Here, each video signal has the video signal level of the B channel 100
The relative signal level is shown as .

As is clear from FIGS. 2B and 3B, the video signals of the R, G, and B channels are signals from which high frequency components have been removed, and the relative values of these signals are affected by the aperture and convex lens 5. This makes white balance adjustment very easy.

Furthermore, recently it has been considered that computers etc. can automatically adjust the white balance using these video signals, but even in this case, it is very easy because the high frequency components of the video signal are removed. .

Here, it is preferable that the convex lens 5 is switched instead of the extender by a turret or a slide for switching the extender. In this case, the convex lens 5 can be inserted with a single touch, and remote control is also possible.

As explained above, according to the mechanism of the present invention, white balance adjustment can be performed simply by inserting a convex lens into the space of the TV lens, and it can also be performed using the subject light, so consideration must be given to light source matching, etc. There's no need to. Furthermore, unlike a diffuser plate, there is less loss of light quantity, so there is less imbalance between adjustment and photographing, making it possible to provide an inexpensive and high-performance television lens blurring mechanism that has never existed before.

[Brief explanation of the drawing]

Fig. 1 shows an optical system showing one embodiment of the present invention;
This figure shows the relative ratio of each video signal when the aperture is open, and FIG. 3 shows the relative ratio of each video signal when the aperture is F4. 1... Zoom lens, 2... Aperture, 3... Relay lens, 4... Imaging surface, 5... Convex lens, 6...
...Extender lens.

Claims (1)

[Scope of Claim for Utility Model Registration] 1. By inserting a convex lens into the relay lens space of a television lens consisting of a zoom lens, the focus is shifted from the normal image plane and white balance adjustment is performed. Features a TV lens blurring mechanism. 2. The television according to claim 1, wherein the television lens is a television lens with a built-in extender, and the convex lens is insertable in conjunction with a turret or slide for switching the extender. Lens blurring mechanism.