JPS6344698B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a filter glass for near-infrared absorption that has excellent spectral transmittance in the wavelength range of 400 to 600 nm and sharp cut characteristics in the wavelength range of 600 to 800 nm.

When measuring the amount of visible light using a photosensitive element having high sensitivity from the long wavelength visible region to the near infrared region, a filter is required to correct the visibility of the photosensitive element to an appropriate value. Conventionally, as this type of filter glass, for example, P ₂ O ₃ - R ₂ O (R is an alkali metal element) is disclosed in Japanese Patent Application Laid-open No. 137357/1983.
―BaO―CuO glass was also introduced in Japanese Patent Application Publication No. 1983-
In the specification of 121924 publication, P ₂ O ₅ ―Al ₂ O ₃ ―R ₂ O―
MgO—BaO—SO ₃ —CuO-based glasses are disclosed, respectively. All of these glasses contain a large amount of P ₂ O ₃ as well as CuO as an essential component, and when melted in an oxidizing atmosphere, Cu ⁺⁺ ions coordinated with many oxygen ions are released into the glass. When formed, it takes on a blue color and exhibits a near-infrared absorption effect centered on about 900 nm. However, these glasses are generally modified by increasing the CuO content to give them certain near-infrared absorption properties.
The spectral transmittance at 400 to 600 nm, especially at 400 to 500 nm, decreases and shows a greening tendency;
Sharp cut characteristics at 800nm deteriorate.
However, since a thinner glass sample requires a higher CuO content, it is difficult to obtain a thin filter with the desired spectral transmittance.

An object of the present invention is to provide an improved infrared absorbing filter glass that eliminates the above-mentioned tendency observed in conventional filter glasses, improves near-infrared absorption characteristics, and prevents greening tendency.

While conducting test research to achieve the above object, the present inventor discovered that a specific range of amounts of Fe ₂ O ₃ and/or CeO ₂ were added to a CuO-containing phosphate base glass with a wide composition range. Depending on the situation, 400~
It has been found that the spectral transmittance at 600 nm and the sharp cut characteristic at 600 to 800 nm are much improved compared to the base glass, and the present invention has been completed. In conventional glasses that do not contain CuO,
It is recognized that the addition of Fe ₂ O ₃ and CeO ₂ adversely affects the above-mentioned effects, and therefore the addition of the above-mentioned components is not indicated in the above-mentioned known documents. If CeO ₂ is added for some purpose, the amount should be kept to an extremely small amount. However, it contained CuO
In glasses mainly composed of P ₂ O ₃ , Fe ₂ O ₃ and
Addition of CeO ₂ has an effect completely opposite to that expected above. This finding is surprising and contrary to common sense.

The feature of the filter glass composition of the present invention based on such new knowledge is that Fe 2 O 3 and/or Fe ₂ O ₃ and/or or
CeO ₂ 0.01-5%, however, Fe ₂ O ₃ 0.01-0.5%,
It contains 0.5 to 5% of CeO ₂ .

In the CuO-phosphate base glass of the present invention
The content of CuO and P ₂ O ₃ can be set to any composition ratio of each of the above components in the conventionally known glass, but the amounts of Fe ₂ O ₃ and CeO ₂ components to be added are limited to the above range. be done. The reason is as follows. i.e. Fe ₂ O ₃ and
When _CeO2 is used alone, the glass has a spectral transmittance of 400-600nm and 600-600nm when the amount of each of their components is less than 0.01% and 0.5%, respectively.
It shows almost no improvement effect on the sharp cut characteristics at 800 nm, and when the amount of these components exceeds 0.5% and 5%, respectively, the spectral transmittance of the glass in the short wavelength visible region, that is, 400 to 500 nm, decreases. It shows a tendency to Further, these components may be used in combination within the above-mentioned ranges, and may be contained in a total amount of 0.01 to 5%, but in this case, CeO ₂ may be contained in an amount of less than 0.5%.

In the present invention, Fe ₂ O ₃ and/or CeO ₂
The CuO-phosphate base glass containing CuO improves the meltability, resistance to devitrification, and chemical durability of the glass, and also contains Cu ⁺⁺ ions coordinated to many oxygen ions in the glass. In order to form stably and obtain the desired spectral transparency, CuO 1 to 1% by weight was added.
8%, _P2O3 50-80%, _{Al2O3 0-11} %, _{SiO2 0}
~5%, _B2O3 0-5 _% , _Li2O 0-6%, _Na2O
0-8%, K ₂ O 0-8%, however, Li ₂ O+
Na ₂ O + K ₂ O 0.5-10%, MgO 0-10%, CaO
0 to 11%, SrO 0 to 15%, BaO 0 to 40%, however, MgO + CaO + SrO + BaO 0 to 40%, ZnO
0-10%, PbO 0-10%, Nb ₂ O ₃ 0-5%,
It is desirable to contain each component in a range of 0 to 0.5% of As ₂ O ₃ and 0 to 5% of Sb ₂ O ₃ . Note that the filter glass of the present invention using the above basic glass composition is
Weigh and mix commonly used raw materials to obtain a predetermined oxide composition, and use a platinum crucible or the like in an oxidizing atmosphere at approximately 1050 to 1350°C and 0.5 to 100°C, depending on the difficulty of melting depending on the composition and melting scale. It is obtained by melting and degassing for 7 hours, stirring and homogenizing at about 900 to 1050°C for 0.5 to 7 hours, and then pouring into a mold and slowly cooling.

Next, 400 nm of the glass samples which are practical composition examples (No. 1 to No. 20) of the filter glass of the present invention,
Transmission at 500nm and 600nm, i.e.
T400 (%), T500 (%) and T600 (%), absorption edge wavelength AW (nm) and _Fe2O3 from these _glasses
and/or the increased change in transmittance at 400 nm and 600 nm in the example compositions described above when compared to a CuO-phosphate base glass sample of the same thickness produced under the same melting conditions with CeO ₂ removed; i.e. ΔT400 (%) and ΔT600
(%) is shown in Table 1. Table 1 shows practical composition example No. 1.
Basic glass composition S-1 common to No. 2 and No.
The basic glass composition S-2 common to No. 3 and No. 4 is shown as a comparative example, respectively. Regarding these example glass samples and the basic glass sample of the comparative example,
Figures 1 and 2 show comparison diagrams of spectral transmittance curves.
It is as follows. Note that ΔT400 and ΔT600 of Examples No. 5 to 20 were also determined in the same manner as in Examples No. 1 to No. 4. As is clear from these charts, all of the glasses of the composition examples of the present invention exhibit superior effects in spectral transmittance in the 400 to 600 nm range and sharp cut properties in the 600 to 800 nm range, compared to conventional glasses of this type. are doing.

As described above, the CuO-phosphate near-infrared absorbing filter glass containing a predetermined amount of Fe ₂ O ₃ and/or CeO ₂ of the present invention has a
Since it has superior spectral transmittance at 600 nm and sharp cut characteristics at 600 to 800 nm, it can be used not only as a visibility correction filter for the photosensitive element, but also as a near-infrared absorption filter for color television cameras, a filter for color printing, etc. Useful.

[Brief explanation of the drawing]

FIG. 1 shows glass sample No. 1 of the composition example of the present invention.
and a comparison diagram of the spectral transmittance curves of No. 2 and basic glass sample S-1. FIG. 2 is a comparison diagram of glass samples No. 3 and No. 4 of composition examples of the present invention and basic glass sample S-2.

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Claims (1)

[Claims] 1 For 100 parts by weight of CuO-phosphate base glass,
In weight%, Fe ₂ O ₃ and/or CeO ₂ 0.01-5
%, however, _{Fe2O3 0.01} ~0.5%, _CeO2 0.5~5
A filter glass for near-infrared absorption characterized by containing %.