WO2003019607A1 - Funnel glass for cathode ray tube - Google Patents

Abstract

A funnel glass for a cathode ray tube capable of preventing the contrast of the cathode ray tube from lowering by absorbing light invaded in the funnel glass thereby, wherein a light transmittance in the range of wavelength of 450 to 650 nm is 80% or less when the wall thickness of the glass is 10 mm, and an X-ray absorption coefficient when the wavelength is 0.06 nm is 40 cm-1 or larger.

Description

 Description Funnel glass for cathode ray tube Technical field

 The present invention relates to a funnel glass for a cathode ray tube. Background art

 The cathode ray tube envelope includes a panel glass on which an image is projected, a tubular neck glass on which an electron gun is mounted, and a funnel-shaped funnel glass connecting the panel glass and the neck glass. Phosphor is coated on the inner surface of the panel glass to display images. The inner and outer surfaces of each of the neck glass and the funnel glass are coated with a carbon conductive film (carbon doug) in order to equalize the potential inside the cathode ray tube bulb when generating an electron beam from the electron gun. In a cathode ray tube, when an applied voltage is applied to the anode, an electron beam is emitted from the electron gun, which is a cathode, and the phosphor attached to the inner surface of the panel glass emits light to display an image on the panel glass. At this time, braking X-rays are generated in the cathode ray tube. Damping X-rays leaking out of the tube through the envelope can have an adverse effect on the human body. For this reason, this type of envelope is required to have high X-ray absorption capacity.

 By the way, the light emitted from the phosphor mainly passes through the panel glass to display an image, but part of the light goes to the funnel side and enters the funnel glass. For example, in the case of a projection type cathode ray tube, since a high voltage and current are applied to the anode, the amount of light generated from the phosphor is particularly large, and therefore, the amount of light entering the funnel glass is also large.

The glass used as the conventional funnel glass is almost colorless and transparent, and the light transmittance at a wavelength of 450-650 nm is about 85% with a glass thickness of 10 mm. Therefore, light that has entered the funnel glass may repeatedly diffuse and reflect on the inner and outer surfaces of the glass and reach the panel glass. Especially In the case of a projection cathode ray tube, the panel glass and the funnel glass are welded to the direct without any frit, so that light is easily guided from the funnel glass to the panel glass. The light guided to the panel glass mixes with the image light, causing a problem of reducing the contrast of the image.

 Therefore, an object of the present invention is to provide a funnel glass for a cathode ray tube, which can prevent a decrease in the contrast of the cathode ray tube. Disclosure of the invention

 As a result of repeating various experiments, the present inventor has found that by reducing the light transmittance in the visible region of the funnel glass for a cathode ray tube, the absorption of light penetrating the glass is increased, and the decrease in the contrast of the cathode ray tube is suppressed. I found that I could do it.

According to one embodiment of the present invention, the light transmittance in a wavelength range of 450 to 65 nm is 80% or less at a glass thickness of 10 mm, and at a wavelength of 0.06 nm. X-ray absorption coefficient of 40 cm- ¹ or more is obtained. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, a funnel glass for a cathode ray tube according to an embodiment of the present invention will be described. In the funnel glass for a cathode ray tube described here, the light transmittance in the wavelength range of 450 to 65 nm is set to 80% or less with a glass thickness of 10 mm. Moreover, the X-ray absorption coefficient at a wavelength of 0.06 nm is set to 40 cm- ¹ or more.

Since this funnel glass has a light transmittance of 80% or less, it has an excellent light absorbing effect. For this reason, of the light emitted from the phosphor attached to the inner surface of the panel glass, the light that has entered the funnel glass is gradually absorbed into the glass while being repeatedly reflected on the inner and outer surfaces of the funnel glass. Therefore, it is necessary to reduce light that is guided from the panel glass to the panel glass and mixed into the image light. And a decrease in contrast can be prevented.

 If the transmittance of the glass is more than 80%, the effect of absorbing light is reduced, so that light mixed into the panel glass cannot be reduced, and the contrast is undesirably reduced. The preferred light transmittance is 60% or less, more preferably 50% or less.

The light transmittance at a wavelength of 450 to 650 nm of the funnel glass to below 80%, for example, Co ₃ 0 ₄ in the glass, N _{I_〇, C r 2 0 3, V} 2 〇 _5, S e0 _2, At least one colorant selected from the group consisting of CuO and MnO may be contained in a total amount of 10 to 50,000 ppm. If the total amount of the coloring agent is less than 10 ppm, the effect of lowering the transmittance of the glass is reduced. If the total amount is more than 50,000 ppm, the meltability of the glass is deteriorated. The preferred range of the total amount of the colorant is 20 to 30,000 ppm.

The funnel glass for a cathode ray tube has a high X-ray absorption coefficient at 0.6 A of 40 cm- ¹ or more, so that X-rays do not leak outside the tube.

Specific compositions usable in this funnel glass, in percent by mass, S I_〇 _{2 48~58%, A 1 2 0} 3 0. 5~6%, PbO 10~30%, MgO 0 ~5%, CaO Less than six%, S R_〇 0 to 9%, B A_〇 0 to 9%, Na ₂ 〇 _{3 ~9%, K 2 0 4~ll} %, Sb 2 0 3 0~1%, colorant 10 It is in the range of 50000 ppm, and it may be selected so as to satisfy the above conditions within this range. The reasons for limiting the glass composition as described above are as follows.

S i〇 ₂ is a component that becomes a glass network former. When the content of Si 含有₂ is 48 to 58% by mass, the molding of the funnel glass becomes easy, and the consistency with the thermal expansion coefficient of the neck glass is improved. The preferred range of the funnel glass is 50-57% by mass.

A 1 ₂ 〇 _{3 is} also a component that becomes the network former of glass. If the amount of A 1 ₂ 0 ₃ is 0.5 to 6% by weight, molding of the funnel glass is facilitated, the tooth may, better consistency between the thermal expansion coefficient of the neck glass. The preferred range of A 1 ₂ 0 ₃ is from 1 to 5 mass%. PbO is a component that increases the X-ray absorption coefficient of glass. When the content of PbO is 10 to 30% by mass, a sufficient X-ray absorption capacity can be obtained, and the viscosity can be adjusted to a value suitable for molding funnel glass. The preferred range of Pb〇 is 15 to 27% by mass.

 Mg〇 is a component that adjusts the coefficient of thermal expansion and viscosity while making glass easier to melt. When the content of MgO is 5% by mass or less, the glass is not easily devitrified, and the liquidus temperature is lowered, so that funnel glass is easily molded. Mg 0 is preferably at most 4% by mass.

 Ca〇 is also a component that adjusts the coefficient of thermal expansion and the viscosity while making glass easier to melt, like MgO. When the content of Ca〇 is 6% by mass or less, the glass is hardly devitrified and the liquidus temperature is lowered, so that funnel glass is easily molded. The preferred range of C a0 is 1 to 5% by mass.

 31 ”〇 and 8 & 0 are components that facilitate melting of glass, adjust the coefficient of thermal expansion and viscosity, and further enhance X-ray absorption. The content of each of SrO and BaO is 9 When the content is less than 10% by mass, the glass is less likely to be devitrified, and the liquidus temperature is lowered, so that funnel glass can be easily formed. 3 Each of 1 "〇 and 8 & 〇 is preferably 7% by mass, respectively. It is as follows.

Na ₂ 〇 is a component that adjusts the coefficient of thermal expansion and viscosity. When the content of Na ₂ 3 is 3 to 9% by mass, the consistency with the thermal expansion coefficient of the neck glass is improved, and the viscosity can be adjusted to be suitable for molding the funnel glass. A preferred range of N a ₂ 0 is 4-8 wt%.

K ₂ 〇 also a component that adjusts the thermal expansion coefficient and viscosity as well as the N a ₂ 0. When the content of K ₂₀ is 4 to 11% by mass, the consistency with the thermal expansion coefficient of the neck glass is improved, and the viscosity can be adjusted to be suitable for molding the funnel glass. The preferred range of { ₂ } is 5 to 10% by mass.

Sb ₂ 〇 ₃ is a component which acts as a fining agent. When the S b ₂ 0 ₃ increases, but the glass tends to be devitrified, no problem as long as the addition of up to 1% by weight. Sb ₂ 〇 ₃ is preferably 0.05 to 0.8 wt%. Furthermore, the cathode-ray tube funnel glass, in addition to the above components, as impurities resulting from the raw materials used, ZnO, that each of Z r0 _2, T I_〇 _2, F e ₂ 0 ₃ including multi Kutomo 2% it can.

 In the above description, the light transmittance is defined based on a glass thickness of 1 Omm, but it goes without saying that the present invention can be applied to any funnel glass having various thicknesses.

 Table 1 shows examples of the present invention (sample Nos. 1 to 4) and comparative examples (sample No. 5).

表中の各試料は、 次のようにして作製した まず、 表の組成となるようにガラス原料を調合し、 白金ポットを用いて 15 00°Cで 4時間溶融した。 尚、 均質なガラスを得るため、 途中で 3分間攪拌し て脱泡を行った。 その後、 溶融ガラスを金型に流し出して所定形状に成形し、 徐冷した。

Each sample in the table was prepared as follows First, glass raw materials were prepared so as to have the composition shown in the table, and were melted at 1500 ° C. for 4 hours using a platinum pot. In order to obtain a homogeneous glass, degassing was performed by stirring for 3 minutes on the way. Thereafter, the molten glass was poured into a mold, formed into a predetermined shape, and gradually cooled.

 The X-ray absorption coefficient, transmittance, thermal expansion coefficient, molding temperature and liquidus temperature of each sample thus obtained were measured and are shown in the table.

 The X-ray absorption coefficient was obtained by calculating the absorption coefficient for a wavelength of 0.06 nm based on the glass composition and density.

 As for the transmittance, after optical polishing was performed so that the glass thickness became 10 mm, the light transmittance at a wavelength of 450 to 650 nm was measured with a spectrophotometer, and the maximum transmittance was shown in the table.

 Regarding the coefficient of thermal expansion, the average coefficient of thermal expansion at 30 to 380 ° C was measured with a dilatometer.

For molding temperature, the temperature was measured at which the viscosity of the glass corresponds to 10 ⁴ dP a · s by platinum ball pulling method. This molding temperature is a guide when molding the molten glass into a predetermined shape, and the lower the temperature, the better the moldability.

 Regarding the liquidus temperature, each sample was first ground and mixed to a size of 300 to 500 m, mixed, placed in a platinum port, transferred to a temperature gradient furnace at 800 to 1200 ° C, and held for 48 hours. Then, a port made of platinum was taken out of the temperature gradient furnace. Then, the glass was taken out of the platinum port. The sample thus obtained was observed with a polarizing microscope, and the crystal precipitation point was measured.

As is clear from the table, each of the samples No. 1 to No. 4 has a high X-ray absorption coefficient of 66 cm- ¹ or more, so that X-rays generated inside the cathode ray tube can be shielded. The maximum transmittance of glass with a wavelength of 450 to 650 nm was as low as 55% or less. Furthermore the thermal expansion coefficient of 101 X 10- ⁷ Z ° C, the panel can be well matched with glass Ya net Kugarasu, molding temperature 966 ° C below the liquidus temperature is lower than 890 ° C, glass Was also excellent in moldability.

On the other hand, the sample of sample No. 5 has the highest wavelength of 450-650 nm glass. The large transmittance was as high as 84%.

 From the above results, the funnel glass prepared from each of Sample Nos.! To No. 4 is superior to the funnel glass prepared from Sample No. 5 in the effect of absorbing light. It can be assumed that it is possible to reduce the light mixed into the panel glass and prevent the contrast from decreasing. Industrial applicability

 The funnel glass for a cathode ray tube of the present invention is suitable as a glass used for manufacturing a funnel for a cathode ray tube.

Claims

The scope of the claims 1. Light transmittance in the wavelength range of 450 to 650 nm is a glass thickness of 10 mm, and 80% or less, and, the wavelength 0. 06 nm definitive X-ray absorption coefficient is 40 cm one ¹ or more Characteristic funnel glass for cathode ray tubes.  2. The funnel glass for a cathode ray tube according to claim 1, wherein the light transmittance is 60% or less.  3. The funnel glass for a cathode ray tube according to claim 1, wherein the light transmittance is 50% or less. 4. _{Co 3 0 4, N i 0} , C r 2 0 3, V 2 0 5, S e0 2, CuO, and the total content of at least one colorant selected from the group of Mn_〇, 10 to 50,000 2. The funnel glass for a cathode ray tube according to claim 1, which contains ppm.  5. The funnel glass for a cathode ray tube according to claim 4, wherein the total amount of the coloring agent is 20 to 30,000 ppm. 6. mass percentage, S I_〇 _{2 48~58%, A 1 2 0} 3 0. 5~6%, Pb_〇 10~30%, 0~5% MgO, C aO 0~6%, S rO 0 ~9%, B aO 0~9%, N a 2 0 3~9%, K 2 0 4~1 1%, S b 2 〇 ₃ 0-1%, claims containing a colorant 10 to 50,000 p pm Item 5. The funnel glass for a cathode ray tube according to item 4 above. 7. The funnel glass for a cathode ray tube according to claim 6, wherein the content of Si ₂ is in the range of 50 to 57% by mass. 8. A 1 ₂ 〇 ₃ for cathode ray tube funnel glass according to claim 6, the content is in the range of from 1 to 5% by weight of.  9. The funnel glass for a cathode ray tube according to claim 6, wherein the content of PbO is in a range of 15 to 27% by mass.  10. The funnel glass for a cathode ray tube according to claim 6, wherein the content of MgO is 4% by mass or less. 11. The method according to claim 6, wherein the content of Ca〇 is in the range of 1 to 5% by mass. Funnel glass for cathode ray tubes.  12. The funnel glass for a cathode ray tube according to claim 6, wherein the content of SrO is 7% by mass or less.  13. The funnel glass for a cathode ray tube according to claim 6, wherein the content of BaO is 7% by mass or less. 14. N a ₂ 0 for a cathode ray tube funnel glass according to claim 6, the content is in the range of 4-8% by weight of. 15. cathode-ray tube funnel glass according to claim 6, the content of K ₂ 0 is in the range of 5 to 10 wt%. 16. Sb ₂ 0 ₃ content is 0.05 to 0. Cathode-ray tube funnel glass according to claim 6 in the range of 8 wt%. _{17. ZnO, Z r0 2, T} i 0 2, F e 2 〇 ₃ for cathode ray tube funnel glass according to claim 6 at most each further comprising 2%.