DE3340387A1 - ELECTRIC BULB AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Abstract

1. Process for manufacturing an electrical incandescent lamp with a mushroom-shaped lamp bulb made of glass which, on its internal surface between the neck of the bulb and the maximum bulb diameter, is provided with an SiO2 layer which reflective to visible radiation and which reflects the radiation in an intensified manner to the bulb bowl, and the bulb bowl of which has an internal surface which diffuses visible radiation, a coating nozzle with a deflector shield attached to it being placed inside the lamp bulb to apply the SiO2 coating, and the fine SiO2 powder particles carried by a gas stream being blown into a heated lamp bowl and applied to the internal wall of the bulb in the electrostatic field, characterized in that the internal surface of the bulb bowl which diffuses visible radiation also consists of an SiO2 coating which is applied in one operating cycle with the coating which is reflective to visible radiation between the neck of the bulb and the maximum bulb diameter, the deflector shield being formed as a flat, circular disc which is positioned concentrically with the coating nozzle and at the level of the maximum bulb diameter, and the bulb bowl of the otherwise heated lamp bulb being cooled during the coating.

Description

Patent Trust Company

for electric light bulbs mbH., Munich

Electric incandescent lamp and process for making the same

The invention relates to an electric incandescent lamp with a mushroom-shaped lamp bulb made of glass, which with an inner silicon layer arranged between the piston neck and the largest piston diameter is, which reflects the light intensified to the piston tip, wherein the piston tip is a light-diffusing surface and a method for manufacturing the lamp.

The light-scattering surface of the bulb tip is usually produced by a hydrofluoric acid matting of the lamp bulb. The internal siliconization is currently carried out using the wet process. Pre-matted standing lamp bulbs are coated with _{paste containing TiO 2} up to the largest bulb diameter, the bulb tip remaining unslurry.

It is known also the light-diffusing surface to produce with an inner silicon layer, which is applied in the wet process. A condensing paste is used certain viscosity (U.S. Patent 3,909 6 ^ 9).

Furthermore, the internal siliconization of lamp bulbs in the dry process is known, in the case of a gas flow borne SiO “powder particles are blown into the lamp bulb and bound to the heated flask glass in an electrostatic field. When the silicon layer only on certain parts of the inner wall of the piston

should extend, can in the carrying the powder particles Gas flow these deflecting means are arranged. So is to keep the tubular dome clear of a bulbous lamp bulb of an electric discharge lamp of powder particles in the area of the largest A circular deflector plate supported by a piston diameter, its side facing away from the coating nozzle is flat, while the side facing the nozzle has a convex shape. The deflection shield is over the Coating nozzle and is arranged concentrically to this. The shield is supported with supporting rods that are anchored in the nozzle area and consists of stainless steel (US Pat. No. 3,279,937).

The object of the invention is to provide an electric incandescent lamp of the type described at the outset with a simpler structure and manufacturing method.

The problem posed is achieved with the features listed in the characterizing part of claim 1. The transition from one layer to the other is essentially sharp-edged. The absorption ratio of the first inner silicon layer, which reflects the light more intensely towards the bulb tip, to the second inner silicon layer applied to the bulb top is in the range from 3 ^: 1 to 15.5 1. A layer thickness ratio of approx. 6: 1 (reflective first layer: more light-scattering second layer) has proven to be particularly advantageous. The layers are applied in one operation using the electrostatic process, with a high voltage potential being applied between the lamp bulb and the coating nozzle. The desired differences in layer density and layer thickness are achieved by means of a circular, flat deflector shield, which is above and concentric with the

Coating nozzle is arranged in the area of the largest piston diameter and divides the powder flow. It is also essential for this process that the piston tip of the heated piston is cooled during the coating. A further significant advantage of this novel coating process is that the interior matting of the lamp bulb by means of hydrofluoric acid can be dispensed with, which significantly reduces the environmental impact.
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The following is an exemplary embodiment. From the figures shown schematically show

FIG. 1 shows an electric incandescent lamp according to the invention in a partially broken away view

FIG. 2 the coating of the lamp bulb

The lamp according to FIG. 1 has a mushroom-shaped lamp bulb 1, a base 2 and a luminous element k held in a frame 3. The lamp bulb 1 is provided on its inner surface with a first siliconizing layer 5, which extends from the bulb neck to the largest bulb diameter and reflects the light to the bulb tip 6 to a greater extent. The second, much thinner silicon layer 7, which adjoins the first layer 5 with a substantially sharp-edged transition and which covers the inner wall of the piston tip 6, causes the light-scattering effect.

The absorption ratio is preferably the first reflective applied on the base side Layer 5 to the thin second layer 7 applied to the piston tip 6 approx. 6: 1. As can be seen from FIG. Both layers are applied in one operation using the electrostatic drying process

the SiQg powder particles carried by an air current at approx. 3.3 bar for approx. 0.5 s are blown into the lamp bulb 1 and deposited in the electrostatic field on the inner wall of the glass bulb. A high voltage of approx. 20 kV is applied between the heated lamp bulb 1 and the coating nozzle 8. The distribution of the layer densities and layer thicknesses is achieved by means of a cooling cap 9 and a circular, flat deflection shield 10. The piston tip 6 is cooled for approx. 10 s with blown air 11 of approx. 2.7 bar. For this purpose, the lamp bulb 1 is fitted with the cooling cap 9, which extends down to the height of the largest bulb diameter and is sealed with a rubber ring 12. The blown air 11 escapes through an opening 13 made in the cooling cap 9. The deflection shield is arranged inside the lamp bulb 1 above and concentrically with the coating nozzle 8, likewise approximately at the level of the largest bulb diameter. The lamp bulb 1, which is heated to about 50 K before the siliconization begins, is kept at a temperature of about 300 K in the area of the bulb tip 6 during the siliconization, while the remaining part of the bulb has about ^ 20 K.

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Claims (2)

Claims Nut electric incandescent lamp with a mushroom-shaped lamp bulb made of glass, which is provided with an inner silicon layer arranged between the bulb neck and the largest bulb diameter, which reflects the light intensified to the bulb top, the bulb top having a light-diffusing surface, characterized in that, in addition to that between the bulb neck and a first inner silicon layer (5) arranged at the largest piston diameter is applied to the untreated inner wall of the piston tip (6) with a second, substantially thinner inner silicon layer (7). 2. Electric incandescent lamp according to claim 1, characterized in that the absorption ratio of the first inner siliconizing layer (5) to the second inner siliconizing layer (7) is in the range from 3 ^: 1 to 15 ' . 3 · A method for producing an electric incandescent lamp according to claim 1, in which by a gas stream carried SiO “powder particles into a heated Blown bulb and - by a circular deflector at the level of the largest bulb diameter deflected - in the electrostatic field on the Kolbess inner wall are applied, characterized in that the two inner silicon layers (5 »7) can be applied in one operation, wherein the deflector (9) is flat and the piston tip (6) is cooled.