GB2034110A

GB2034110A - Headlight having metallized reflector coating

Info

Publication number: GB2034110A
Application number: GB7937440A
Authority: GB
Original assignee: GTE Sylvania Inc
Current assignee: GTE Sylvania Inc
Priority date: 1978-10-30
Filing date: 1979-10-29
Publication date: 1980-05-29
Also published as: FR2441794A1; DE2942371A1; IT7926709A0; FR2441794B3; BE879684A; IT1125562B; NL7907917A

Abstract

A filament-containing headlight has a glass reflector (1) having a metallic reflector coating (6) thereon. The reflector has bosses (8) having holes therethrough to accommodate lead-in wires (4) for the filament. The area (7) around the boss region is kept devoid of reflecting coating. <IMAGE>

Description

SPECIFICATION Headlight having metalized reflector coating This invention is concerned with automobile headlights comprising a tungsten-halogen lamp within a reflector envelope. Examples of such headlights are disclosed in Patent Specifications Nos. 7907753 Serial number 2015822 and 7914955 Serial number 2019998 the disclosures of which are incorporated herein by reference. The invention is particularly concerned with Type 2 headlights, that is to say, those having both a high beam and a iow beam filament. In such lamps the glass reflector has three ferrule bosses thereon to accommodate the three filament lead-in wires, as shown in U.S. Patent Specification No.

3,898,451. In the prior art, when the glass was aluminized to provide a reflecting surface, the area around and within the region defined by the three bosses was also aluminized.

We have found that glare can be reduced by making the glass area around and within the region defined by the three bosses devoid of reflecting coating. This area, which is somewhat distorted because of the three bosses, thus does not contribute to forward light reflection and glare is thereby reduced. The area devoid of reflecting material should not be so large, however, as to significantly reduce the desired main beam illumination.

The invention is illustrated by way of example in the accompanying drawings, the single figure of which is a perspective view, partly in section, of a headlight in accordance with one embodiment of this invention.

Referring to the drawing, a headlight comprises a glass reflector 1 having a lens 2 bounded to the front thereof. A the rear of reflector 1 are three bosses 8 having holes therethrough through which extend lead-in wires 4 for a tungsten halogen lamp 5, shown diagrammatically in broken lines. The internal rear surface of the glass reflector 1 is provided with a reflecting coating 6 except for the area 7 which is the area around and within the triangular region defined by the bosses 8.

The reflective coating 6 may be aluminized on the glass reflector 1 in the manner shown in U.S.

Patent Specification No.2,160,714, for example.

However, prior to aluminizing, a protective shield, made, for example, of 20 mil thick stainless steel sheet, is disposed over the area 7 to prevent deposit of aluminium thereon. The shield is about the same shape as the area 7 and is held in place during aluminizing by being fastened to two or three rods which extend through the holes in bosses 8 and which are clamped to hold the shield in place. In one example, one of the rods was threaded, and the clamping was accomplished by a wingnut which was threaded onto the rod at the rear of the glass reflector. After aluminizing, the shield is removed and the lamp is completed in the usual manner.

Several lamps having a reflective coating in the area 7 were measured at specific test points as specified in SAE Standard J579C entitled "Sealed Beam Headlamp Units for Motor Vehicles". The coating in the area 7 was then removed and the measurements were then repeated on the same lamps. The glare light as measured at 1 up, 1 21 left and 210 up, 2" right was reduced by an average of 8.8% by removing the reflecting coating in the area 7, while the desirable mainbeam light as measured at IC down, 130 right and 130 down, 20 right was reduced only an average of 2.1%. It is expected that an even greater average reduction in glare light will be obtained by not depositing reflecting coating on area 7 in the first place.

In order to further reduce glare, it may be desirable also to coat the press-sealed end 9 of the tungsten-halogen capsule 5 with an opaque coating, as disclosed in U.S. Patent Specification No. 3.784.861.This blocks the rearward emitted radiation from the filament, which can be undesirably refracted because the glass at the rear of the capsule 5 changes from a tubular shape to a press seal shape. However, for manufacturing convenience, the opaque coating need not be limited to a specified area as described in U.S.A.

Patent Specification No. 3,784,861 but can include the entire press seal.

This invention may also be used with the usual type of Type 2 headlight, such as shown in U.S.A.

Patent Specification No. 3,898,451, which does not contain a capsule. It may even be more advantageous in this case because the step of sealing ferrules to the bosses require the glass to be heated to its softening point, which can cause additional distortion of the area 7.

This invention can also be applicable to type 1 headlights, which contain no low beam filament and therefore are not involved in the above discussed type of glare problem, but which utilize metal eyelets as disclosed in Patent Specification No. 7907753 Serial number 201 5822 instead of ferrules-fused-to-the-glass as disclosed in U.S.A.

Patent Specification No.3,898,451. If the entire surface of the reflector 1 were aluminized, the aluminium coating would effectively short circuit the eyelets to each other. Removing the metallic reflecting coating from around each boss area or shielding each such area during the aluminizing step prevents such short circuiting.

1. A motor vehicle filament-containing headlight comprising a lens bonded to the front of a glass reflector having a metallic reflecting coating' the reflector having bosses having holes therethrough to accommodate lead-in wires for the headlight filament or filaments, and the reflector being devoid cf reflecting coating in an area at about the region around the bosses.

2. A headlight as daimed in Claim 1 , wherein the area devoid of reflecting coating is such as to reduce headlight glare.

3. A headlight as claimed in Claim 2, wherein the area devoid of reflecting coating is sufficientiy small so as to not significantly reduce desired main beam illumination.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Headlight having metalized reflector coating This invention is concerned with automobile headlights comprising a tungsten-halogen lamp within a reflector envelope. Examples of such headlights are disclosed in Patent Specifications Nos. 7907753 Serial number 2015822 and 7914955 Serial number 2019998 the disclosures of which are incorporated herein by reference. The invention is particularly concerned with Type 2 headlights, that is to say, those having both a high beam and a iow beam filament. In such lamps the glass reflector has three ferrule bosses thereon to accommodate the three filament lead-in wires, as shown in U.S. Patent Specification No. 3,898,451. In the prior art, when the glass was aluminized to provide a reflecting surface, the area around and within the region defined by the three bosses was also aluminized. We have found that glare can be reduced by making the glass area around and within the region defined by the three bosses devoid of reflecting coating. This area, which is somewhat distorted because of the three bosses, thus does not contribute to forward light reflection and glare is thereby reduced. The area devoid of reflecting material should not be so large, however, as to significantly reduce the desired main beam illumination. The invention is illustrated by way of example in the accompanying drawings, the single figure of which is a perspective view, partly in section, of a headlight in accordance with one embodiment of this invention. Referring to the drawing, a headlight comprises a glass reflector 1 having a lens 2 bounded to the front thereof. A the rear of reflector 1 are three bosses 8 having holes therethrough through which extend lead-in wires 4 for a tungsten halogen lamp 5, shown diagrammatically in broken lines. The internal rear surface of the glass reflector 1 is provided with a reflecting coating 6 except for the area 7 which is the area around and within the triangular region defined by the bosses 8. The reflective coating 6 may be aluminized on the glass reflector 1 in the manner shown in U.S. Patent Specification No.2,160,714, for example. However, prior to aluminizing, a protective shield, made, for example, of 20 mil thick stainless steel sheet, is disposed over the area 7 to prevent deposit of aluminium thereon. The shield is about the same shape as the area 7 and is held in place during aluminizing by being fastened to two or three rods which extend through the holes in bosses 8 and which are clamped to hold the shield in place. In one example, one of the rods was threaded, and the clamping was accomplished by a wingnut which was threaded onto the rod at the rear of the glass reflector. After aluminizing, the shield is removed and the lamp is completed in the usual manner. Several lamps having a reflective coating in the area 7 were measured at specific test points as specified in SAE Standard J579C entitled "Sealed Beam Headlamp Units for Motor Vehicles". The coating in the area 7 was then removed and the measurements were then repeated on the same lamps. The glare light as measured at 1 up, 1 21 left and 210 up, 2" right was reduced by an average of 8.8% by removing the reflecting coating in the area 7, while the desirable mainbeam light as measured at IC down, 130 right and 130 down, 20 right was reduced only an average of 2.1%. It is expected that an even greater average reduction in glare light will be obtained by not depositing reflecting coating on area 7 in the first place. In order to further reduce glare, it may be desirable also to coat the press-sealed end 9 of the tungsten-halogen capsule 5 with an opaque coating, as disclosed in U.S. Patent Specification No. 3.784.861.This blocks the rearward emitted radiation from the filament, which can be undesirably refracted because the glass at the rear of the capsule 5 changes from a tubular shape to a press seal shape. However, for manufacturing convenience, the opaque coating need not be limited to a specified area as described in U.S.A. Patent Specification No. 3,784,861 but can include the entire press seal. This invention may also be used with the usual type of Type 2 headlight, such as shown in U.S.A. Patent Specification No. 3,898,451, which does not contain a capsule. It may even be more advantageous in this case because the step of sealing ferrules to the bosses require the glass to be heated to its softening point, which can cause additional distortion of the area 7. This invention can also be applicable to type 1 headlights, which contain no low beam filament and therefore are not involved in the above discussed type of glare problem, but which utilize metal eyelets as disclosed in Patent Specification No. 7907753 Serial number 201 5822 instead of ferrules-fused-to-the-glass as disclosed in U.S.A. Patent Specification No.3,898,451. If the entire surface of the reflector 1 were aluminized, the aluminium coating would effectively short circuit the eyelets to each other. Removing the metallic reflecting coating from around each boss area or shielding each such area during the aluminizing step prevents such short circuiting. CLAIMS

4. A headlight as claimed in any one of Claims 1-3, wherein the reflector contains three bosses defining a triangle and the area devoid of reflecting coating includes the triangular region bounded by the three bosses.

5. A headlight as claimed in any one of Claims 1-4, wherein metal eyelets are disposed in the holes in the bosses and the area devoid of reflecting coating is such as to prevent electrical continuity between said eyelets via said coating.

6. A headlight as claimed in Claim 2 or any one of Claims 3-5 as appended thereto, wherein the headlight contains a tungsten-halogen capsule and glare is further reduced because of an opaque coating on the press-sealed end of the capsule.

7. A motor vehicle headlight comprising a lens bonded to the front of a curved glass reflector and containing a tubulartungsen-halogen capsule having a press seal at one end thereof, the capsule being mounted substantially along the axis of the reflector with the press seal end rearward, and the press seal end of the capsule being coated with an opaque coating extending onto the tubular portion of the capsule.

8. A motor vehicle headlight substantially as described herein with reference to the accompanying drawing.

9. The features as herein described, or their equivalents, in any novel selection.