Method of producing a halogen lamp and halogen lamp

Abstract

The present invention relates to a method for producing a halogen lamp, including the following steps: providing a glass tube blanket; dip-coating of the glass tube blanket using a sol gel process having an inorganic coating; forming a lamp bulb from the coated glass tube blanket. The present invention relates further to a halogen lamp produced accordingly.

Claims

1. A method of producing a halogen lamp, the method comprising: providing a glass tube blanket; dip-coating the glass tube blanket using a sol gel process having an inorganic coating; forming a lamp bulb from the coated glass tube blanket.

2. The method of claim 1, wherein the glass tube blanket is suspended and dipped in the sol for dip-coating such that an end portion of the glass tube blanket remains uncoated.

3. The method of claim 2, wherein electrical components of the halogen lamp are introduced into the glass tube blanket for forming the lamp bulb and are melted portion-wise in the uncoated end portion of the glass tube blanket.

4. The method of claim 1, wherein the glass tube blanket is made of hard glass.

5. The method of claim 1, wherein a low pressure is generated in the inner cavity volume of the glass tube blanket for coating the inner surface of the glass tube blanket such that a sol determined for the sol gel process rises up until a predefined extent within the cavity.

6. The method of claim 1, wherein the coating is applied during dip-coating both on the inner surface and on the outer surface of the glass tube blanket.

7. The method of claim 1, wherein the coating applied during a dip-coating comprises a coating reflecting infrared radiation.

8. The method of claim 7, wherein the dip-coating of the glass tube blanket using a sol gel process comprises a structure of an alternating layer system, which comprises in particular between 5 and 30 single layers and having a thickness of 0.3 m to 3 m.

9. The method of claim 7, wherein the alternating layer system alternately comprises single layers having a high and low refraction index.

10. The method of claim 7, wherein the dip-coating of the glass tube blanket using a sol gel process comprises applying at least a transparent layer having nano pigments reflecting infrared radiation.

11. The method of claim 1, wherein the dip-coating of the glass tube blanket using a sol gel process comprises applying an absorption layer.

12. The method of claim 1, wherein the sol gel process comprises a pull out step of the pulling out of the glass tube blanket from the sol, at a relative humidity of the ambient air between 30% and 70%.

13. The method of claim 1, wherein the sol gel process comprises a tempering step in which the glass tube blanket pulled out from the sol is exposed to a bake-out temperature between 250 C. and 550 C.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) For a more complete understanding of the disclosure, reference should be made to the following detailed description and accompanying drawings, wherein:

(2) FIG. 1 shows a method for producing a halogen lamp;

(3) FIG. 2a shows a glass tube blanket;

(4) FIGS. 2b-2e show steps of forming a lamp bulb from a glass tube blanket according to FIG. 2a;

(5) FIG. 2f shows a lamp bulb which is coated on the outside;

(6) FIG. 2g shows a halogen lamp comprising a lamp bulb according to FIG. 2f;

(7) FIG. 3 shows a method for producing a halogen lamp according to the present invention;

(8) FIG. 4a shows a glass tube blanket;

(9) FIG. 4b shows a dip-coated glass tube blanket according to the present invention;

(10) FIGS. 4c-4f show steps of forming a lamp bulb from the coated glass tube blanket of FIG. 4b;

(11) FIG. 4g shows a halogen lamp comprising a lamp bulb of FIG. 4f according to the present invention;

(12) FIG. 5 shows a schematic cross-section view of a dip-coated glass tube blanket according to the present invention;

(13) FIG. 6 shows a schematic cross-sectional view taken along the line illustrated in FIG. 5;

(14) FIG. 7 shows a cross-sectional view according to FIG. 6, illustrating an alternative layer structure; and

(15) FIG. 8 shows the steps of dip-coating a glass tube blanket using a sol gel process.

(16) The accompanying figures of the drawing should provide a more complete understanding of the embodiments of the present invention. The figures illustrate embodiments and serve to explain the principles and concepts of the invention in conjunction with the disclosure. Other embodiments and many of the mentioned advantages result in view of the drawings. The elements of the drawings are not necessarily shown to scale with respect to each other.

(17) In the figures of the drawing like reference numerals refer to like parts, features, and components having the same functionality and operation unless it is stated otherwise.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

(18) FIG. 1 in conjunction with FIGS. 2a to 2d shows a method for producing a halogen lamp which is known to the inventor. The method comprises steps S1 to S7. Herein the individual steps are explained with respect to FIGS. 2a to 2g which illustrate the respective state of the individual method steps during the production.

(19) First step S1 refers to providing a glass tube blanket as is shown in FIG. 2a. The glass tube blanket 101 of FIG. 2a is made of for instance quartz glass or hard glass and is constructed as a circular hollow body illustrated in FIG. 2a in a side view. The length of the glass tube blanket 101 is already cut to the length required for producing a lamp bulb 103. Such an appropriate length is for example 8 cm. A glass tube blanket 101 which is thus cut to the correct length for producing a lamp bulb 103 is referred to as sprengling (i.e. a cut off piece).

(20) Subsequent step S2 comprises the introduction of a pipette-like tapering 109 into the glass tube blanket 101. The tapering 109 is achieved by locally annealing and simultaneously lengthening the glass tube blanket 101 in the area which is provided for the tapering 109. Thereby, the diameter is greatly reduced locally, for example to a constant inner diameter of 1 millimeter, creating a tapered portion also referred to as capillary.

(21) In the next step S3 electrical components of the halogen lamp 110 to be completed are introduced into the cavity of the glass tube blanket 101 at the end of the glass tube blanket 1 opposite the tapering or capillary 109, as is shown in FIG. 2c. The electrical components comprise two contact pins 105a and 105b as well as a glow filament 105c electrically connected in between.

(22) In the subsequent step S4 the electrical components are, as is illustrated in FIG. 2d, melted with the glass tube blanket 101 by crimping the end of the glass tube blanket 101 opposite the capillary to a support portion 106. For the glass tube blanket 101 made of quartz glass this is typically performed at temperatures in a range between 1500 C. and 1600 C. By this crimping step, the glass tube blanket is gas-tightly sealed in the area of the support portion 106 on the one hand, and on the other hand the pins 105a and 105b are fixedly mounted therein.

(23) After the crimping step and in a subsequent step, which is not disclosed here in detail, the lamp bulb 103 which is now formed into its basic shape is firstly purged with a gas for cleaning and is then evacuated. Thereafter the bulb is filled with a predetermined gas filling which typically contains mainly inert gases as well as halogen additives.

(24) In a last forming step S5 the capillary is then cut at its narrowest position and is sealed gas-tightly using a glass drop such that the state illustrated in FIG. 2e of a completely formed lamp bulb 103 is achieved. In this condition the lamp bulb 103 could already been used in a halogen lamp.

(25) To increase the efficiency of a halogen lamp or to modify the spectrum or the color of the light emitted from the halogen lamp the completed lamp bulb 103 may be coated additionally using a coating 102, as is illustrated in FIG. 2f. Such a coating may for instance be applied using a PVD method (physical vapor deposition) on the exterior of the lamp bulb 103 or may be vapor-deposited.

(26) The lamp bulb 103 which is finalized in such a manner may then be processed in a subsequent step S7, for instance into an automotive halogen lamp 110, or may be assembled into a completed halogen lamp for a different field of application by mounting the lamp bulb 103 to a lamp socket 111. In addition, the lamp bulb 103 may be blackened at the tip by using a black colored surface paint 112.

(27) As an alternative to step S7 the lamb bulb 103, after being completed in step S6, may for example be prepared for use in household lights by suitably forming the pins 105a, 105b to be received in a household lamp socket.

(28) FIG. 3 shows a method for producing a halogen lamp according to the present invention. The inventive method comprises steps P1 to P7, wherein the individual steps are explained herein in detail with reference to FIGS. 4a to 4g illustrating the respective producing state of the individual steps.

(29) In a first step P1 a glass tube blanket 1 is provided, as is shown in FIG. 4a. In contrast to the glass tube blanket 101 of FIG. 2a, this glass tube blanket 1 of FIG. 4a is not made of quartz glass, but is made of hard glass. The external or geometric shape of the glass tube blanket 1 is identical to the shape of the glass tube blanket 101 of FIG. 2a.

(30) In a subsequent step P2 the glass tube blanket 1 is coated by using a sol gel process using an inorganic coating 2. To perform this step the glass tube blanket 1 is suspended first by grabbing the glass tube blanket 1 in an area of an end portion 4 by means of a grabber. Then the glass tube blanket 1 is dipped into a sol by using the grabber, however, without the end portion 4 being dipped as well. The end portion 4 of the glass tube blanket 1 therefore remains uncoated.

(31) Step P2 further comprises a pullout step of pulling out the glass tube blanket from the sol leading to a gel film, as well as a tempering step for firing or baking the layer into a ceramic, wherein the layer is applied by being dipped into the sol. With reference to FIG. 8 these individual steps will be explained in more detail below.

(32) Subsequent to step P2 a glass tube blanket is thus provided which is coated with a ceramic layer. If multiple layers are to be provided, for example in the form of an alternating layer system, step P2 may be repeated multiple times. With respect to an alternating layer system this is performed using different sols for producing different individual layers of the coating 2 which will be explained in more detail with reference to FIG. 6.

(33) In step P3 subsequent to step P2 the glass tube blanket 1 is provided with a tapering 9, as is illustrated in FIG. 4C. Again, this is performed by locally annealing and lengthening. However, in contrast to FIG. 2b where step S2 is achieved, this is performed at a glass tube blanket 1 made of hard glass and already coated using an inorganic layer at significantly lower temperatures in the range of 1100 C. to 1300 C.

(34) In subsequent step P4 electrical components of the halogen lamp to be completed are introduced into the cavity of glass tube blanket 1, in analogy to step S3 according to FIG. 1. This is performed at the end opposite to tapering 9 at which end the uncoated end portion 4 is provided. The electric components comprise two contact pins 5a and 5b as well as a glow filament 5c being electrically connected in between the two contact pins of which are arranged coaxially to the axis of the glass tube blanket 1 or the later to be finished lamp bulb 103, respectively.

(35) In subsequent step P5 the electrical components are melted section-wise into the glass tube blanket 1, as is illustrated in FIG. 4d. Herein it is important that for melting the electrical components only the uncoated end portion 4 of the glass tube blanket 1 is crimped or pressed into a support portion 6. Since the glass tube blanket is made of hard glass, this may be performed at temperatures starting from 1100 C. Thus, it is avoided that the coating is damaged at the coated portion. Due to the absence of a coating in the uncoated end portion 4, formation of bubbles or a foaming of the glass material is further avoided during crimping.

(36) Subsequent to step P5 and in analogy to step S4 the bulb created by crimping is cleaned, evacuated, and filled with gas.

(37) Then the capillary is cut in the area of the tapering 9 in a subsequent step P6 which is the last step of forming the lamp bulb 3, and is leak tightly sealed using a glass drop. The state thus achieved is illustrated in FIG. 4f.

(38) By mounting on a lamp socket the further processing to achieve a halogen lamp is now performed in step P7, in analogy to step S7. For example, this may be a lamp socket for an automotive application. Additionally, a black surface paint 12 may be provided at the tip of the lamp bulb for avoidance of undefined light emission.

(39) Also in analogy to step S7, a lamp bulb according to FIG. 4f may be deformed at its pins such that the lamp bulb corresponds to a conventional household lamp standard, as an alternative to step P7.

(40) With respect to FIG. 5 a cross-section view of a coated glass tube blanket 1 is shown according to the present invention. The glass tube blanket 1 is provided with an inorganic coating 2 both on its inner surface 7 and on its outer surface 8, respectively. Such a coating both on the inner surface 7 and on the outer surface 8 is provided using dip-coating of the glass tube blanket 1 by means of a sol gel process. The inorganic coating 2 may be constructed in different ways and may have different functionalities.

(41) A particularly advantageous functionality of halogen lamps is the provision of a reflection band for infrared light. Such a layer which reflects infrared light may be implemented for example by using a system of alternating layers.

(42) FIG. 6 shows a schematic cross-section view along the cross-section line (longitudinal cross-section) illustrated in FIG. 5, in the case of such an alternating layer system.

(43) Accordingly, the glass tube blanket 1 has an inorganic coating 2 on its inner surface 7 and on its outer surface 8, respectively, the coating of which has been formed with an alternating layer system. The alternating layer system comprises two different types of single layers 2a and 2b having different refractive indices, respectively, in particular a high refractive index and a low refractive index. For example, the first type of single layers 2a provides a silicon oxide layer and the second type of single layers 2b provides a titanium oxide layer.

(44) With reference to the exemplary embodiments illustrated, a total of nine single layers are provided on the inner surface 7 and on the outer surface 8, respectively, with a silicon oxide layer 2a and a titanium oxide layer 2b consistently alternating and stacked on top of each other. Such an alternating layer system is manufactured by repeating the dip coating using a sol gel process multiple times with different sols, that means in the exemplary case a total of nine times.

(45) With reference to FIG. 8 the steps of dip-coating P2a to P2c of a glass tube blanket 1 are illustrated in detail using a sol gel process.

(46) In a first step P2a the glass tube blanket which is suspended for example by using a grabber is dipped into a sol. This is preferably performed such that an end portion 4 of the glass tube blanket 1 remains uncoated. For precisely adjusting the extent or height of the coating 2 within the inner cavity of the glass tube blanket 1 a low pressure may be adjusted in the inner cavity of the glass tube blanket 1 to achieve a predetermined height of the coating 2 on the inner surface 7.

(47) In a second step P2b, illustrating a pull out action, the glass tube blanket 1 is pulled out from the sol. It is important at this step that the relative humidity of the ambient air is between 30% and 70% in order to achieve a consistent or homogeneous coating. Further, the layer thickness gradient may be adjusted by varying the pull out speed.

(48) After the pullout step a sol film is provided on the glass tube blanket, which is dried during and after the pulling out. Meanwhile a hydrolysis and condensation reactions of components of the sol (so-called precursor molecules) are performed until a gel layer is formed from the sol film.

(49) In a third step P2c the coating is tempered. This means that organic components are transformed into inorganic component. This occurs at bake-out temperatures of between 250 C. and 550 C. wherein best results are achieved at temperatures of between 500 C. and 550 C.

(50) With continued reference to FIG. 6 an alternating layer system may be implemented by multiply repeating the dip-coating using the sol gel process with different sols. For this, the different sols are utilized for each repeating step in an alternating manner such that the different single layers 2a and 2b are created alternatingly. This is repeated so many times until the desired number of single layers or until the desired total layer thickness is achieved. Higher reflective factors may be achieved by providing more single layers 2a, 2b.

(51) FIG. 7 shows a cross-section view of a glass tube blanket having an alternative layer structure similar to the one of FIG. 6. In the case of FIG. 7 the glass tube blanket 1 has a transparent layer 2c comprising infrared radiation reflecting nano pigments on its inner surface 7 and on its outer surface 8, respectively, which are schematically indicated by the dots of layers 2c. Such nano pigments are disclosed for example in DE 10 2005 061 684 A1.

(52) In order to apply the layer 2c using a sol gel process the nano pigments are provided in a sol in combination with precursors, which are provided for and suitable for forming a transparent layer. The precursors for forming a transparent layer comprise preferably silicates or silicon oxide, in other words a silicate sol. By a singular dip-coating step according to a method of FIG. 8 a layer 2c is applied on the glass tube blanket. Preferably this layer has a relatively large thickness of 1 micron to 2 microns which may be simplified by a pull out process having a relatively high pull out speed.

(53) Although the present invention is described with respect to preferred exemplary embodiments herein, the invention is not limited thereto and may be modified in numerous ways.

(54) In addition, meanwhile an absorption layer may be provided in the exemplary embodiments according to FIG. 6 or 7 above or below the infrared radiation reflecting layer which may cause a coloration of the lamp bulb for exam-le.

(55) Furthermore, a purely absorbing coating may be provided as an alternative coating 2 instead of one of the coatings illustrated in FIG. 6 or FIG. 7.

(56) Still further, the glow filament 5c in the lamp bulb 3 may also be positioned in a different manner, for instance parallel to the bulb axis, angled or transverse to the bulb axis.

LIST OF REFERENCE NUMERALS AND SIGNS

(57) 1 glass tube blanket 2 coating 2a first single layer 2b second single layer 2c transparent layer having infrared radiation reflecting nano pigments 3 lamp bulb 4 uncoated end portion 5a, 5b contact pins 5c glow filament 6 support portion 7 inner surface 8 outer surface 9 tapering or capillary 10 halogen lamp 11 lamp socket 12 black surface paint 101 glass tube blanket 102 coating 103 lamp bulb 105a, 105b contact pins 105c glow filament 106 support portion 109 tapering or capillary 110 halogen lamp 111 lamp socket 112 black surface paint S1-S7 method steps P1-P7 method steps