JPS59126391A - Optical fiber device of color television camera - Google Patents

Abstract

PURPOSE:To attain correct supply to a white color detecting region without being leaked to a pickup region where an output light from an optical fiber plays a major role by providing a fiber fixing jig so that an output end of an optical fiber is made in parallel with a photodetecting face of an image pickup element. CONSTITUTION:The fiber fixing jig 25 is adhered closely to a target face 27 of an image pickup tube 26 and the output end face of the arranged optical fibers is made coincident with a white color detecting region 28 of the target face 27. Black coating 38 is applied to the optical fiber between a light collector and a fiber fixing jig 25 so as to avoid input/output and reflection of unnecessary light. The optical fiber 30 is configured of two kinds of raw materials having different refractive index and a prescribed spread angle 31 exits to the irradiated light depending on the raw material. Thus, as the optical fibers, those having a small spread angle 31 are used and most of the optical fiber output light is made incident vertically to the target face 32 by fixing the output end face of the optical fiber and the target face 32 in parallel.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an optical fiber device that can be used in an automatic white balance adjustment device for a single-tube or single-panel color television camera.

Conventional configurations and their problems In recent years, with the spread of home VTRs, simple color television cameras have also become popular.

In order to meet market demands for low cost, light weight, and compact size, simple color television cameras have become mainstream with single-tube cameras that use optical color separation filters.

One of the essential adjustments for color television cameras is white balance adjustment. the current.

One of the most commonly used methods is to photograph a white plate in advance, or to insert a light diffuser plate between the imaging lens and the imaging tube to capture a uniformly restricted amount of white light. There is a preset method in which the color signal processing circuit is adjusted so that the carrier color signal in the camera's output signal 3-2 is zero.

Since the above-mentioned conventional method is a preset method, it is necessary to readjust it in response to changes in illumination during photographing, which is extremely troublesome in terms of camera operability.

FIG. 1 is a block diagram schematically showing a method that improves the drawbacks of the conventional method and enables automatic white balance adjustment in real time in response to arbitrary changes in illumination during shooting. Further, FIG. 2 shows an example of the configuration of the image pickup tube target surface. An object is imaged by an imaging lens 1 onto a main imaging area 22 on a target surface 3 of an imaging tube 2. White light, which serves as a reference for white balance adjustment, is collected by a condenser 4 that collects light around the subject, and is transmitted via an optical fiber 5 to a white detection area 2 provided on a part of the target surface 3 of the image pickup tube 2.
3. Here, the camera deflection scans the main imaging area 22 and the white detection area 23 on the target surface.
configured to scan.

The output signal 6 taken out from the image pickup tube is amplified by a preamplifier 7 and supplied to a color separation circuit 8, where it is output as a luminance signal 9.
Red primary color signal 10. The signal is separated into a blue primary color signal 11. The red primary color signal 10 is sent to the subtracter 1 via the variable gain amplifier 12R.
On the other hand, the luminance signal 9 is also supplied to the subtracter 13R, and a difference signal 14R between the two signals is output. Difference signal 1
4R is supplied to a white detector 1esR. The white detector 15R extracts a difference signal 14R corresponding to the white detection area 23 on the image pickup tube target surface, and outputs a signal for controlling the gain of the variable gain amplifier 12H in response to the extracted difference signal. Similarly, regarding the blue primary color signal 11,
Variable gain amplifier 12B, subtracter 13B, white detector 15
B is used to configure a feedback loop and output a difference signal 14B. Note that a sampling pulse 16 is supplied to the white detectors 1sR and 15B.

Both difference signals 14R and 14B are supplied to a modulator 17 and modulated by a color subcarrier 18 to output a carrier color signal 19. The carrier color signal 19 and the luminance signal 9 are supplied to the 5-page output circuit 2o, and a required video signal 21 is obtained. In the above configuration, the variable gain amplifier 1 is configured such that the carrier color signal 19 corresponding to the white detection area 23 is always zero.
2R, 12B, subtractor 13R213B, white detector 15
By constructing a feedback loop using R and 16B, an automatic white balance adjustment device capable of responding in real time can be realized.

The automatic white balance adjustment device based on the above configuration is already known, but the most important problem in realizing this device, which is the method of supplying the output light of the optical fiber to the image pickup tube target surface, is as follows. No specific configuration is shown. If one end of the fiber is simply brought into close contact with the target surface, the output light from the one end of the fiber may leak into the main imaging area 22, or the optical fiber may prevent the light rays from the subject from forming an image on the target surface. This poses a major problem in realizing an automatic white balance adjustment device.

OBJECTS OF THE INVENTION It is an object of the present invention to use a 6-beam automatic white balance adjustment device of a color television camera, and
Another object of the present invention is to provide an optical fiber device for a color television camera that is capable of separating light incident on the white detection area 23.

Structure of the Invention The optical fiber device for a color television camera of the present invention has a fiber fixing jig that supports the optical fiber so that the output end of the optical fiber is parallel to the light receiving surface of the image sensor. This has the effect that the output light from the optical fiber does not leak into the main imaging area 22 and is correctly supplied to the white detection area 23.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 is a perspective view showing one embodiment of the present invention. As shown in FIG. 1, the input end face of the optical fiber 24 has a
Light around the object collected by the condenser 4 is incident.

The output ends of the optical fibers are aligned to match the shape of the seven-way white detection area 23 and fixed by a fiber fixing jig 26.

Note that it is easier to use a plurality of fibers with a smaller diameter in terms of shaping. In addition, the fiber fixing jig 26 is arranged so as not to block the light rays that contribute to image formation of the subject light.
Along with making the center part hollow.

It is made of a black material that absorbs light so as not to generate unnecessary reflected or scattered light.

The fiber fixing jig 25 configured as described above is brought into close contact with the target surface 27 of the image pickup tube 26, and is fixed so that the output end surfaces of the aligned optical fibers coincide with the white detection area 28 on the target surface 2. . 29 is the main imaging area.

Further, the optical fiber between the condenser 4 and the fiber fixing jig 26 is coated with a black coating 38 to prevent unwanted light from coming out or being reflected.

Next, the fixing angle of the optical fiber in the fiber fixing jig 26 will be explained using FIG. 4. Fourth
The diagram is based on the XYZ rectangular coordinates shown in Figure 3.
It shows a cross-sectional view on a plane. optical fiber 30
As is well known, it is composed of two types of materials with different refractive indexes.

A certain spread angle 31 exists in the emitted light depending on the material. If the spread angle 31 is large, the fiber fixing jig 25
Even if the front surface 32 of the target surface is brought into close contact with the target surface, the fiber output light will not reach the face plate 33 that constitutes the target.
Since the particles are scattered more widely and reach the photoconductive film 34, they also leak into the above-mentioned main imaging area 29, causing color unevenness in the photographed image and deteriorating the image quality. Therefore, an optical fiber with a small spread angle 31 is used, and the output end face of the optical fiber and the target face 3
By fixing the optical fibers 2 in parallel, it is necessary to configure the optical fiber so that the majority of the output light is incident perpendicularly to the target surface 32.

FIG. 5 and FIG. 6 also show the fiber fixing jig 26.
This figure shows another configuration example, and shows a cross-sectional view on the xZ plane. Figure 6 shows the fiber fixing jig 2.
It has nine pages in which one end surface of the optical fiber is provided inside by a width 36 from the target surface side 35 of No. 6, and is effective in reducing the spread angle 31. FIG. 6 further shows an optical fiber output end face,
By providing a condensing lens 37 between the front surface 32 of the target surface, the spread angle 31 can be made smaller.

In each of the above embodiments, the fiber fixing jig is described as having a circular outer shape, but the present invention is applicable regardless of the outer shape as long as unnecessary reflection or scattering of light does not occur. be able to. Furthermore, although the above embodiments have been described with reference to a single tube type color television camera, the present invention can also be applied to a single tube type color television camera.

Effects of the Invention As is clear from the above explanation, the present invention is configured such that the output end face of the optical fiber is parallel to the image pickup tube target surface, so there is little leakage of the fiber output light to the main imaging area, and automatic imaging is possible. When applied to a white balance adjustment device, the image quality of the effective screen is less likely to deteriorate. Also,
By using a condensing lens between the output end of the optical fiber and the target surface, it is possible to further reduce the leakage of light. By configuring fixing jigs and optical fibers,
A high-quality automatic white balance adjustment device can be realized.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an automatic white balance adjustment device for a single-tube color television camera. 2 is a diagram showing the configuration of the image pickup tube target surface used in the device shown in FIG. 1, FIG. 3 is a perspective view showing one embodiment of the optical fiber device of the present invention, and FIGS. The figure is a sectional view showing each side of a fiber fixing jig used in the optical fiber device of the present invention. 1... Image pickup lens, 2. 26... Image pickup tube, 3°27... Image pickup tube target surface, 4...
...Concentrator, 5゜24.30...Optical fiber, 7...Preamplifier, 8...Color separation circuit, 12R, 12B...・Variable gain amplifier,
1sR, 13B...Subtractor, 15R, 15B1
1 pemi''...White detector, 17...Modulator, 2
o... Output circuit, 21... Video signal,
22, 29... Main imaging area, 23, 28...
...White detection area, 25...Fiber fixing jig, 33...Face plate, 34.
...Photoconductive film, 37... Condensing lens.

Claims (1)

[Scope of Claims] (1) An optical fiber for a color television camera, characterized in that a fiber fixing jig is configured to support the optical fiber so that the output end face of the optical fiber is parallel to the light receiving surface of an image sensor. Device. (no) The color television camera according to claim (1), wherein the fiber fixing jig is disposed at a position that does not block incident light to the main imaging area of the light receiving surface of the image sensor. Optical fiber device. (3) An optical fiber for a color television camera according to claim (1), characterized in that a condenser lens is disposed between the output end face of the optical fiber and the light receiving surface of the image sensor. (→ An optical fiber 2 base for a color television camera according to claim (1), characterized in that the portions of the optical fiber other than the input and output end faces are coated with black.
Three devices.