JPH0219092A - Color separation filter - Google Patents

Abstract

PURPOSE:To obtain excellent color reproducibility by specifying the spectral characteristic of 3 primary color filters as a color separation means. CONSTITUTION:A red color filter has a spectral characteristic having a maximum toward longer wavelengths than a wavelength of 640nm and a blue color filter has a spectral characteristic having a maximum toward shorter wavelengths than a wavelength of 440nm in the color separation filter where 3 primary color red, green and blue filters are arranged repetitively in a stripe. Thus, the spectral characteristic of the color filters is set properly to obtain the color separation filters suitable when the spectral characteristic of the color filters is set properly and the filters are used for the optical system such as a color video camera or a color television camera able to reproduce colors in an excellent way.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a color separation filter, and more particularly to a stripe-shaped color separation filter used by being incorporated into an optical system such as a color video camera or a color television camera. .

(Prior Art) Conventionally, in optical systems such as color video cameras and color television cameras, color separation means for color reproducibility is disposed in front of an image pickup device such as a CCD or an image pickup tube.

As the color separation means, for example, a so-called stripe filter in which red, green, and blue striped color filters are arranged repeatedly at a constant pitch is often used because of its simple configuration.

The color filters for color separation are set to have predetermined spectral transmission characteristics, and the light that has passed through each color filter is guided to a COD, an image pickup tube, etc., and color reproduction is thereby performed.

Generally, the imaging characteristics of the three primary colors are set to approximately match the spectral characteristics of the so-called NTSC system.

The spectral characteristics shown in this NTSC system are ideal and have negative sensitivity, and in reality, it is impossible to obtain a color separation filter that can obtain such spectral characteristics.

For this reason, the three primary color filter is constructed using, for example, an optical multilayer film such as a dichroic film so that its spectral characteristics are as close to ideal imaging characteristics as possible.

However, in order to obtain good color reproducibility, it is not enough to simply match the peak wavelengths of the spectral characteristics of the three primary color filters to the ideal spectral characteristics of the three primary color filters; It is important to do so.

(Problems to be Solved by the Invention) The present invention provides a method for improving color separation by appropriately setting the spectral characteristics of the color filters when stripe filters of the three primary colors red, green, and blue are used as color separation means. The purpose of the present invention is to provide a color separation filter suitable for use in optical systems such as color video cameras and color television cameras capable of color reproducibility.

(Means for solving the problem) In a color separation filter having a configuration in which red, green, and blue filters of three primary colors are repeatedly arranged in a stripe pattern, the red filter has a spectral characteristic that has a maximum value at a wavelength longer than 640 nm. The blue filter is configured to have a spectral characteristic having a maximum value on the shorter wavelength side than the wavelength of 440 nm.

(Example) FIG. 1 is an explanatory diagram of the spectral characteristics of an example of the color separation filter of the present invention.

In the figure, R is the red filter, G is the green filter, and B is the spectral transmittance of each stripe filter of the blue filter.

In this example, as shown in the figure, the peak wavelengths of the spectral transmittance of the red filter are set to longer wavelengths than approximately 643 nm and 640 nm, and the peak wavelengths of the spectral transmittance of the blue filter are set to be approximately 438 nm and 440 nm. As will be described later, each color filter is configured so that the wavelength is on the shorter wavelength side.

As a result, the spectral characteristics of each of the three primary color filters are set to approximate ideal imaging characteristics.

FIG. 3 is an explanatory diagram showing color reproduction characteristics on a vectorscope when a color par chart is imaged using the color separation filter according to the present invention.

In the figure, the "○" mark indicates the case where the color separation filter according to the present invention is used. For reference, the "x" marks are images taken with a conventional video camera having the spectral characteristics shown in FIG. In the figure, in addition to red, green, and blue filters, complementary colors of these colors, cyan, magenta, and yellow, are also shown in the same way.

As shown in the figure, the color separation filter according to the present invention is used.
It can be seen that the saturation is better reproduced than when the conventional color separation filter shown in FIG. 2 is used.

The color filter according to this embodiment can be, for example, a color filter dyed with a dye or a multilayer interference thin film.

Next, Table 1 shows an example in which each color filter was constructed on a transparent substrate using a dyeing method using an organic dye.
2 shows an example of a film configuration using a multilayer interference thin film.

(Table-1) Red filter; Irgazin ED 2800 AJ! g.

Green filter; Phthalocyanine blue; 1350 people thick Easto gen Super Yellow; 3000 people thick Blue filter: Phthalocyanine blue: 6000 people thick (Table-2) 7th layer 6th layer 5th layer 4th layer 3rd layer 2nd layer 1st layer Tie, (refractive index n-2, 33) Si02 (refractive index n-1, 45) Si02 Si02 Tie2 Si02 Tie2 Thickness included/4 person/2 person/4 person/4 person/4 person/2 person/4 Two red filters = 610 nm.

Green filter: person = 540 ntn.

Two blue filters = 440 nm (Effect of the invention) According to the present invention, by setting the spectral characteristics of the three primary color filters as color separation means as described above, the output signals from each image sensor can be maintained appropriately. It is possible to achieve a color separation filter suitable for use in optical systems such as color video cameras and color television cameras, which has good color reproducibility and an improved S/N ratio of color reproducibility. .

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of the spectral characteristics of the color separation filter according to the present invention, Fig. 2 is an explanatory diagram of the spectral characteristics of a color separation filter used in conventional video cameras, etc., and Fig. 3 is an explanatory diagram of the spectral characteristics of the color separation filter according to the present invention. FIG. 3 is an explanatory diagram of a vector scope when imaging a color par chart using a decomposition filter. 1 in the figure. R is a red filter, G is a green filter, B
indicates the spectral characteristics of the blue filter. length (nm)

Claims (1)

[Claims] (1) In a color separation filter configured by repeatedly arranging three primary color red, green, and blue filters in a striped pattern,
The red filter has a spectral characteristic with a maximum value at a wavelength longer than 640 nm, and the blue filter has a wavelength of 440 nm.
A color separation filter characterized in that it is configured to have spectral characteristics having a maximum value on the wavelength side shorter than nm.