FIELD OF INVENTION
This invention relates to HID (High Intensity discharge) headlamp unit with safety lock for prevention of electrical/thermal hazard to user. The safety lock is particularly provided in back cover of the high intensity discharge headlamp.
BACKGROUND/PRIOR ART '
HID headlamp unit in a vehicle comprises of HID unit (Ballast, HID Bulb & High Voltage cable) which is mounted inside Headlamp Housing. The housing forming a cylindrical member accommodating a plurality of parts including HID ballast system with sorne caution label to deter the user from touching the ballast system. The ballast system steps up voltage upto 30KV. In case user attempts to replace the HID system, he may receive electrical/thermal shock which may lead to fatal accident. Further owing to very high temperature upto 120°C of the ballast system, the operator may suffer burn injuries.
In order to avoid the above situation the HID Ballast unit is placed in an inaccessible location of vehicle(down side of Headlamp) as shown in fig. 1 according to one prior art indicating HID bulb (B), Igniter (I) and ballast (T). It is provided with simple dust cover without any locking. Hence igniter can be accessed, which can lead to accident due to high voltage.
In case the HID Ballast unit is positioned in accessible location of vehicle, the housing (1) of the headlamp unit is covered by means of a dust cover (2) as indicated in fig. 2. The cover is integrated to an extended part (3), which is used to open the cover.
The shortcoming with this provision is that the dust cover is not provided with any locking means to prevent the user from opening it for replacement/repair

of the HID ballast system. This may cause accident due to high voltage and temperature of the ballast system.
To offer a solution to the above problem another known art has been suggested lor which reference may be made to fig. 3. An additional cover (4) is placed over dust cover (D). However, provision of additional cover (4) contributes to weight, which finally adds to cost of vehicle.
In view of the above, it is required to develop an alternative which can provide an effective solution to the existing problem without increasing weight and cost of vehicle.
OBJECTS OF THE INVENTION
The principal object of the present invention is to provide HID headlamp unit with safety lock for prevention of electrical/thermal hazard to user.
Another object of the present invention is to provide HID headlamp unit with safety lock for prevention of electrical/thermal hazard to user which obviates drawbacks of prior art.
Still another object of the present invention is to provide HID headlamp unit with safety lock for prevention of electrical/thermal hazard to user which is simple in construction.
Yet.another object of the present invention is to provide HID headlamp unit with safety lock for prevention of electrical/thermal hazard to user which is cost effective.

SUMMARY OF THE INVENTION
According to this invention, HID headlamp unit is provided with safety lock for prevention of electrical/thermal hazard to user comprising a housing with a back cover accommodating ballast system, wherein the housing with back cover is provided with a locking means.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Further objects and advantages of this invention will be more apparent from the ensuing description when read in conjunction with the accompanying drawings of exemplary embodiments of invention and wherein:

Fig. 1 shows:
Fig. 2 shows:
Fig. 3 shows:
Fig. 4 shows:
Fig. 5 shows:
Fig. 6 shows: Fig. 7 shows: Fig. 8 shows:

HID Ballast unit in Headlamp is situated in inaccessible
location of vehicle according to known art;
HID Ballast unit mounted inside of Housing without any
safety lock according to prior art;
Conventional housing of HID headlamp unit with double
cover;
Top view of housing of HID headlamp unit with cover
according to present invention;
Side view of housing of HID headlamp unit with cover
according to present invention;
Screw used in the invention;
Tool used in the invention;
Assembly between housing, back cover and screw of present
invention.

DETAIL DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS
The instant invention makes a disclosure regarding HID headlamp unit with safety lock for prevention of electrical/thermal hazard to user, which does not necessitate major constructional variation in the existing lamp unit situated at accessible location.
The present invention has been devised to accommodate a safety lock for avoiding electrical/thermal hazard to user constituting a safety measure.
Now reference may be made to fig. 4-7, in which the HID headlamp unit comprises a housing (lA) with a back cover (2A}. The housing is normally cylindrical in shape without restricting scope of the invention to the same.
The housing is integrated to boss (3A) on its outer peripheral surface.The boss comprises a tubular member as shown in the figure.
The back cover is provided with a locking lug (4A) in fig. 4. The lug is integrated to the cover at its outer periphery.
Said lug is having a flat part (5) with a hole therein. The flat part is integrated to an extended part (6) on one side. Said extended part (6) constituting an extension is employed for application of force while opening/ closing the cover. Absence of the extension would have required comparatively more force for opening/closing the cover. Hence the provision of the extension has been made in the invention. The extension is placed at an inclination with respect to the surface of said flat part.

The cover is screwed to the adjoining housing by means of a tool. The screw is accommodated in the boss through the hole in the lug. Said screw as shown in fig. 6 is a special type of screw, head of which includes a hexagonal groove requiring said tool (fig.7) for screwing/unscrewing. The tool comprises tool with corresponding hexagonal tip to be inserted into the groove for opening/closing the cover. The groove in the head of screw and the tool tip need not necessarily be hexagonal in shape, alternatively it can form other shapes which are not commonly available in the. market rendering it difficult to access by the users. So that the users will be compelled to visit service station for repair/replacement of ballast system, which will prevent them from undertaking the same task thereby avoiding the hazard related thereto. Thus, the safety of users can be accomplished by means of present invention.
Now reference may be made to fig. 8 illustrating assembly between back cover (1') with lug (2') and housing (3') with boss (4') and ballast (6') with the help of said screw (5'). The cover and housing are rigid parts made of resin by injection molding without restricting scope of the invention to the same. Thus other materials/methods readily apparent to a person skilled in the art are understood to be within perview of the invention.

Advantageous Features
- Addressing safety issues of users.
- Cost effective solution to the existing problem.
- Less weight comparatively, which in turn results in improved fuel efficiency.
- Easy to manufacture.
It is to be noted that the present invention is susceptible to modifications, adaptations and changes by those skilled in the art. Such variant embodiments employing the concepts and features of this invention are intended to be within the scope of the present invention, which is further set forth under the following claims:-

We Claim:
1. HID headlamp unit with safety lock for prevention of electrical/thermal hazard to user comprising a housing with a back cover accommodating ballast system, wherein the housing with back cover is provided with a locking means.
2. HID headlamp unit with safety lock for prevention of electrical/thermal hazard to user as claimed in claim 1 wherein the housing is provided with a boss on its outer peripheral surface.
3. HID headlamp unit with safety lock for prevention of electrical/thermal hazard to user as claimed in claim 1 or 2 wherein the cover is having a locking lug at outer periphery thereof.
4. HID headlamp unit with safety lock for prevention of electrical/thermal hazard to user as claimed in any of the preceding claims wherein the housing and the cover is integrated to said boss and said lug respectively.
5. HID headlamp unit with safety lock for. prevention of electrical/thermal" hazard to user as claimed in any of the preceding claims wherein the lug includes a flat part with a hole integrated to an extended part on one side thereof.
6. HID headlamp unit with safety lock for prevention of electrical/thermal hazard to user as claimed in any of the preceding claims wherein the extended part is disposed at an inclination with respect to the flat part, which is utilized for application of force during opening/closing the cover.

7. HID headlamp unit with safety lock for prevention of electrical/thermal
hazard to user as claimed in any of the preceding claims wherein the
cover is screwed to the housing by means of a screw and a tool.
8. HID headlamp unit with safety lock for prevention of electrical/thermal
. hazard to user as claimed in any of the preceding claims is associated
with the advantageous features such as herein described.
9. HID headlamp unit with safety lock for prevention of electrical/thermal
hazard to user substantially as herein described with reference to the
accompanying drawings.