JPS5942282B2 - Kougakuirobunkai Stripe Filter Noseizouhouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to optical systems such as color television cameras, and in particular to a method for manufacturing an optical color separation stripe filter necessary for obtaining color signals of two or more colors from a single image pickup tube. be.

First, in order to facilitate understanding of the present invention, the optical system of a frequency-separated two-tube color television camera using an optical color separation stripe filter and the spectral characteristics of the optical filter will be described as an example. 11 in Figure 1
12 is an objective lens, 12 is an infrared cut filter, 13 is a prism, 14 is an optical low-pass filter, 15 is an imaging tube for U-color signals with a built-in optical color separation stripe filter, and 16 is an imaging tube for luminance signals. The prism 13 has spectral characteristics as shown by curve A in FIG. Prika・
The blue light component and red light component transmitted by the image pickup tube 15
The green light component incident on the camera and reflected by the prism is sent to the image pickup tube 16.
incident on the The image pickup tube 15 has a built-in optical color separation stripe filter that blocks blue light and transmits red light, and has spectral characteristics as shown by curve B in FIG. 2.
Here, if the red light transmittance of the part where the optical color separation stripe filter is not formed and the red light transmittance of the part where it is formed are not the same value, it may cause a false color signal to be generated. . In order to eliminate this drawback, it is necessary to improve the red light transmittance of the optical color separation stripe filter, or to substantially reduce the red light transmittance of the part where the optical color separation stripe filter is not formed. Proposals have been made to reduce the The optical color separation stripe filter materials used include gelatin filters that use organic dyes and dichroic filters that utilize the interference of light that occurs when thin films of high refractive index and thin films of low refractive index made of inorganic materials are alternately layered. ing. However, gelatin filters have drawbacks such as poor heat resistance, and dichroic filters are difficult to manufacture and expensive. In order to overcome these drawbacks, an optical color separation stripe filter that utilizes the basic absorption edge of a thin film material has been provided, but there is a problem in that the spectral transmittance of such an optical color separation stripe filter varies greatly depending on the manufacturing method. An object of the present invention is to solve the above-mentioned problems and provide a method for manufacturing an optical color separation stripe filter 1 in which the spectral transmittance of the optical color separation stripe filter 1 can be improved. The present invention will be explained below with reference to the embodiment diagram shown in FIG. 3. As shown in FIG. 0.2-1 at °C
．． Next, the film is deposited to a thickness of 5 μm and then heat treated at 350 to 700° C. for 3 to 30 minutes in vacuum or inert gas.

Thereafter, the optical color separation filter film 32a is photoetched to form a striped optical color separation filter film 32b as shown in FIG. 3B. Then, heat treatment was performed again at 350 to 70°C in vacuum or inert gas for 30 minutes.
A desired optical color separation stripe filter is manufactured by the process described above for ~30 minutes. Conventionally, heat treatment in vacuum or in an inert gas was not performed at all. Curve A shows the spectral transmittance obtained by the conventional manufacturing method, and curve B in FIG. 4 shows the spectral transmittance obtained by the manufacturing method of the present invention. The spectral transmittance of the optical color separation stripe filter has been improved.The filter material is not only ZnTe but also CdS, Gap, etc.
, a solid solution of ZuSe and ZnTe, a solid solution of CdS and CdSe, etc., whose fundamental absorption edge is in the range of 500 to 570 (Nm), can be used to create a single-tube or two-tube optical color separation stripe filter. It is easy to think that these materials can be used as
Similar to Te, it was confirmed that the spectral transmittance can be improved by heat treatment in vacuum or in an inert gas. o If the heat treatment temperature is below 350°C, it will take a very long time and no noticeable improvement in transmittance will be observed. At temperatures above 0 or 700°C, a decrease in transmittance is often observed and reproducibility is poor. Approximately 55
Heat treatment at 0°C for about 5 minutes improves the transmittance the most.As another example, the red light transmittance of the part where the optical color separation stripe filter is formed and the part where it is not formed are substantially the same. Even when it is desired to have a structure in which the values are the same, if a material that utilizes at least the basic absorption edge of a thin film material is used as the material for the optical color separation stripe filter, manufacturing of the optical color separation stripe filter according to the present invention is possible. This can be achieved by adopting this method. Since the present invention is as described above, it is possible to produce an optical color separation stripe filter with improved spectral transmittance.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing the optical system and image pickup tube of a frequency-separated two-tube color television camera, and FIG. 2 is a characteristic diagram showing the spectral characteristics of the prism and the spectral characteristics of the optical color separation stripe filter. 3A and 3B are explanatory diagrams for manufacturing an optical color separation stripe filter according to an embodiment of the present invention, and FIG. 4 is a diagram showing the spectral characteristics of a ZnTe filter obtained by a conventional manufacturing method and the manufacturing method of the present invention. This is a characteristic diagram showing the spectral characteristics of the obtained ZnTe filter, in which 31 is a transparent substrate, 32a is an optical color separation filter film, and 32b is a striped optical color separation filter film.

Claims (1)

[Claims] 1 At least 500 to 570 (nm) on a transparent substrate
An optical color separation filter film having a basic absorption edge is formed on the substrate, and heat treatment is performed at 350 to 700°C in vacuum or in an inert gas to form the optical color separation filter film into stripes. 350-70 in active gas
A method for producing an optical color separation stripe filter, characterized by subjecting it to heat treatment at 0°C.