JPH0616452A - Front glass for hid lamp - Google Patents

Abstract

PURPOSE:To provide a glass suitable for front side glass of HID lamp without causing coloring and cracks, even irradiated with U.V. rays. CONSTITUTION:This glass has the composition consisting of, by wt. 60-85% SiO2, 0.5-8% Al2O3, 0-8% (Na2O+K2O+Li2O), 0-5% (CaO+MgO), 10-20% B2O3, 0.1-2% (CeO2+TiO2), and 0.1-3% (F+Cl+P2O5+Sb2O3+As2O5+PbO). U.V. rays are absorbed with CeO2 and TiO2 and also coloring of the glass is prevented and generation of stress in the glass caused by irradiation of U.V. rays is suppressed by F, Cl and P2O5, etc., thus the prescribed object is attained.

Description

Detailed Description of the Invention

[0001]

The present invention relates to HID (high intensity discharge)
The present invention relates to a glass suitable for a front glass of a light source with ultraviolet radiation such as a lamp.

[0002]

2. Description of the Related Art HID lamps have mainly been used as outdoor lighting, facility lighting for sports facilities, factories and the like. However, in recent years, the features that HID lamps have such as high power consumption with low power consumption and long life have been noticed, and the miniaturization of the lamp itself has progressed. It is considered to be used for applications such as lighting equipment and automobile headlights.

Conventionally, incandescent light bulbs such as halogen lamps have been used for these lighting applications, and the front glass of a light bulb with a reflector and the headlight lens of an automobile have high heat resistance because of high temperature of the light source. Borosilicate glass, which has excellent translucency, is used.

It is known that HID lamps emit a large amount of ultraviolet rays simultaneously with visible rays. For this reason, conventionally, glass with an ultraviolet absorber added to absorb harmful ultraviolet rays has been used for an envelope bulb such as a mercury lamp which serves as an ultraviolet ray source to prevent ultraviolet radiation from a light source.

[0005]

However, in recent years, with the miniaturization of HID lamps as described above, the envelope bulb of the lamp is no longer used, and it becomes difficult for the envelope bulb to absorb ultraviolet rays. The arc tube of the lamp itself is made of quartz glass and transmits ultraviolet rays. For this reason, when borosilicate glass, which has been conventionally used for the front glass of a light bulb with a reflecting mirror or the headlight lens of an automobile, is used as the front glass of a lighting device having a HID lamp as a light source, the glass is colored by UV irradiation. Or the internal stress is generated in the glass to cause cracks. The coloring of the glass causes a decrease in illuminance and color rendering, and the generation of unnecessary internal stress has a problem that it is damaged during use, especially in a headlight lens of an automobile in which the temperature difference between the inside and outside of the lamp becomes large.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a glass suitable as a front glass for an HID lamp, which does not cause coloring or cracking even when irradiated with ultraviolet rays.

[0007]

In order to achieve the above object, the present invention provides a borosilicate glass having a specific composition with at least one of TiO ₂ or CeO ₂ and F, Cl, P ₂ O ₅ ,
It is a material in which at least one component selected from Sb ₂ O _{3 and} PbO is added together. That is, in the present invention, by weight%, SiO ₂ 60 to 85%, Al ₂ O ₃ 0.5 to 8
%, Na ₂ O + K ₂ O + Li ₂ O 0-8%, CaO +
MgO 0-5%, B ₂ O ₃ 10-20%, CeO ₂ +
TiO ₂ 0.1-2%, F + Cl + P ₂ O ₅ + Sb ₂ O
_A front glass for an HID lamp, which has a composition of 0.1 to 3% of ₃ + As ₂ O ₅ + PbO.

[0008]

The action of each component constituting the present invention and the reason for limiting the composition range as described above will be described below.

SiO ₂ is a main component for forming glass, but if it is less than 60%, the chemical durability of glass deteriorates, and
If it exceeds 5%, the viscosity of the glass becomes so high that melting and molding becomes difficult. Addition of Al ₂ O ₃ has the effect of improving chemical durability, but if it is less than 0.5%, it has no effect, and if it exceeds 5%, the viscosity during melting increases and a homogeneous glass is obtained. Absent. Na ₂ O, K ₂ O and Li ₂ O can be added to improve the meltability of the glass, but if the total amount exceeds 10%, the chemical durability deteriorates.
Addition of CaO and MgO is effective in improving the chemical durability and electrical insulation of the glass and adjusting the high temperature viscosity, but if the total amount exceeds 5%, the devitrification tendency becomes stronger, which is not preferable. Like SiO ₂ , B ₂ O ₃ is a main component forming the present glass, but if it is less than 10%, the melting property of the glass deteriorates, and if it exceeds 20%, phase separation occurs in the glass and a homogeneous glass is obtained. Absent. CeO ₂ and TiO ₂ are added as essential components for preventing coloring of glass by ultraviolet rays,
If the total amount of CeO ₂ and TiO ₂ is less than 0.1%, a sufficient coloring preventing effect cannot be obtained, and even if added in excess of 2%, there is no significant change in the coloring preventing effect. Since coloring due to these components themselves appears, the content is limited to 2%. F, Cl, P ₂ O ₅ , Sb ₂ O ₃ , As ₂ O ₅ , P
bO is added in order to prevent or reduce the generation of internal stress due to ultraviolet irradiation of borosilicate glass, but if the total amount of these is less than 0.1%, a sufficient effect cannot be obtained, and bO is added in excess of 3%. However, no significant effect can be obtained when 3% is added.

The glass of the present invention has a basic composition of borosilicate glass, and can maintain the same heat resistance as the front glass of a conventional light bulb with a reflector and the headlight lens of an automobile.

[0011]

EXAMPLES Examples of the present invention will be described below. Examples of the present invention are shown in Table 1. Sample No.1 to No.1 in Table 1
No. 2 is an example of the present invention, and No. 13 is a conventional example. Further, the composition in the table is shown by weight%.

[0012] In each of these glasses, raw materials are mixed so as to obtain a predetermined component composition, and each glass is housed in a platinum crucible, melted at a temperature of 1500 to 1600 ° C, sufficiently stirred and clarified, and then in a mold. After casting, slowly cooling, then cutting /
The sample was polished and formed into a flat plate having a thickness of 3 mm, and used as a sample for transmittance measurement and stress measurement.

These samples were irradiated with ultraviolet rays for 300 hours using a Sunshine Weather Meter manufactured by Suga Test Instruments Co., Ltd., and the stress generated in the samples after irradiation was measured.
Similarly, the transmittance at a wavelength of 400 nm before and after irradiation with ultraviolet rays was measured, and the change in transmittance before and after irradiation (transmittance difference)
The degree of coloring of the glass was evaluated. The results of these measurements are shown in Table 1.

[0014]

[Table 1] It can be seen from Table 1 that the glass of the examples according to the present invention has a small change in transmittance after irradiation with ultraviolet rays and has an excellent effect of preventing coloring against ultraviolet rays. Further, the stress generated by the irradiation of ultraviolet rays is extremely small or hardly generated.

[0015]

As described above, the front glass for an HID lamp of the present invention uses TiO ₂ or C as a coloring preventing agent.
By adding eO ₂ , coloring of the glass due to the lighting of the lamp can be prevented, and the colorless and transparent state can be maintained for a long period of time. Further, since ultraviolet ray absorbing properties are imparted by these components and the ultraviolet rays emitted from the light source are cut off by the front glass, the irradiated object is not adversely affected by the ultraviolet rays. Furthermore, F, Cl, P
By adding a stress generation preventing component such as 2 O5, generation of stress on the glass surface due to ultraviolet irradiation can be suppressed, and generation of cracks or damage can be prevented.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location H01J 61/30 C 7135-5E

Claims (1)

[Claims] 1. SiO ₂ 60-85% by weight, Al
₂ O ₃ 0.5-8%, Na ₂ O + K ₂ O + Li ₂ O 0
~8%, CaO + 0~5% MgO , B 2 O 3 10~2
0%, CeO ₂ + TiO ₂ 0.1-2%, F + Cl + P
₂ O ₅ + Sb ₂ O ₃ + As ₂ O ₅ + PbO 0.1-3
% Front glass for HID lamps.