FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A wiping unit for wiping the closing ends of the coated tube of a compact fluorescent lamp
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai - 400 030, Maharashtra, India, an Indian Company
INVENTOR
Kumar Vinit, of Crompton Greaves Ltd, L2 Division, Baroda, India, an Indian National
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:


FIELD OF THE INVENTION
This invention relates to a wiping unit for wiping the closing ends of the coated tube of a
compact fluorescent lamp
BACKGROUND OF THE INVENTION
Manufacture of a compact fluorescent lamp (CFL) includes the steps of coating the inside of a blow moulded U-shaped glass tube with a substance capable of converting UV radiation into visible light such as triband phosphorous powder followed by drying the coated tube, sealing the closing ends of the tube and evacuating the tube. In order to seal the closing ends of the tube effectively and prevent leakage of vacuum from the tube, the powder coating at the inner sides of the closing ends of the tube is wiped off and removed. This is carried out in a wiping unit comprising a pair of wiper assemblies vertically disposed and spaced apart from each other at a distance corresponding to the distance between the closing ends of a coated and dried tube. The wiper assemblies are disposed for rotation about a vertical axis and are contra rotatable. Each of the wiper assemblies comprises a slotted pin comprising a flared portion at the lower end thereof and an open slot at the upper end thereof. A rubber scraper is fitted in the slot at the upper end of the slotted pin. A shaft extends to the slotted pin through a bush over which the flared portion of the slotted pin is rotatabiy held. The bush is mounted over a base plate which in turn is mounted on the frame of the wiper unit. The shaft is coupled to the slotted pin with a grub screw. The lower ends of the shafts of the wiper assemblies are coupled to a drive arrangement to contra rotate the shafts. During operation of the wiping unit, the scrapers at the upper ends of the slotted pins engaged in the closing ends of the coated and dried tube held above the wiping unit, rotate in opposite directions so as to scrape down the powder coating at the inner surfaces of the closing ends of the tube.

Because of the grub screw fitment of the shaft and slotted pin during rotation of the wiper assemblies the grub screws loosen very frequently, many times in a day. As a result, the grub screws are to be replaced in order to ensure a tight fit between the slotted pins and shafts. As a result of loosening of the grub screws, there is also play between the slotted pins and the shafts and they tend to rotate relatively. This not only disturbs the smooth rotation of the wiper assemblies, but also creates wear and tear to the slotted pins and shafts. This requires the wiper assemblies to be replaced periodically. Because of the periodic replacement of the grub screws and the wiper assemblies, maintenance of the wiper unit is very expensive, life of the wiper unit is reduced and productivity is reduced. The bushes are truncated conical shaped and short. The powder being scraped down from the closing ends of the tube accumulates on the bottom plate. Because of the engagement surface between the slotted pin and the bush is very close to the bottom plate, the powder getting accumulated on the bottom plate easily rises and enters the clearance between the slotted pin and the bush and jam the slotted pin unless the powder is wiped off and removed very frequently. This is not only cumbersome and inconvenient to carry out but also further increases the downtime and reduces productivity. Jamming of the slotted pin on the bush may also damage the drive arrangement of the wiping unit.
OBJECTS OF THE INVENTION
An object of the invention is to provide a wiping unit for wiping the closing ends of the coated tube of a compact fluorescent lamp which unit has long life and which unit is practically maintenance free and ensures trouble free and smooth operation for a long period of time.

Another object of the invention is provide a wiping unit for wiping the closing ends of the coated tube of a compact fluorescent lamp which unit increases the productivity and is economical.
Another object of the invention is provide a wiping unit for wiping the closing ends of the coated tube of a compact fluorescent lamp which unit is simple in construction and easy and convenient to operate.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a wiping unit for wiping the closing ends of the coated tube of a compact fluorescent lamp, the wiping unit comprising a pair of wiper assemblies disposed vertically in a spaced apart relationship corresponding to the spacing between the closing ends of the coated tube held above the wiper assemblies, the wiper assemblies being disposed for contra rotation about a vertical axis, each of the wiper assemblies comprising a slotted pin having a flared portion at the lower end thereof and rotatably disposed over a bush mounted on a base plate which in turn is mounted on the frame of the wiping unit, a shaft extending into the slotted pin through the base plate, frame and bush, the lower ends of the shafts of the wiper assemblies being coupled to a drive arrangement for rotation of the wiper assemblies in opposite directions, the upper ends of the slotted pins being provided with open slots fitted with scrapers adapted to engaged in the closing ends of the coated tube in close contact therewith, wherein the slotted pin and the shaft of each of the wiper assemblies is coupled together in thread engagement tightened in a direction opposite to the direction of rotation of each of the wiper assemblies and wherein the bush of each of the wiper assemblies comprises a truncated cone shaped portion and cylindrical portion in co-axial relationship.

The following is a detailed description of the invention with reference to the accompanying drawings, in which the sole Fig 1 is a partly crossectional view of the wiping unit for wiping the closing ends of the coated tube of a compact fluorescent tube according to an embodiment of the invention. The wiping unit 1 as illustrated in Fig 1 of the accompanying drawings comprises a pair of wiper assemblies 2 which are disposed vertically in a spaced apart relationship corresponding to the spacing between the closing ends of the coated tube (not shown) of a compact fluorescent lamp (not shown) held above the wiping unit. Each of the wiper assemblies comprises a slotted pin 3 having a flared portion 4 at the lower end thereof. The flared portion is rotatably located over a bush 5 which is mounted on a base plate 6 which in turn is mounted on the frame 7 of the wiping unit. 8 is a shaft extending into the slotted pin through the frame, base plate and bush. The slotted pin and shaft are coupled to each other in thread engagement. The bush comprises a truncated cone shaped portion 5a and a cylindrical portion 5b in coaxial relationship integrally formed as a single piece. However, the bush also can be two piece construction. The drive arrangement of the wiper assemblies comprises a motor 9 and a driver pulley 10 mounted on the shaft 11 of the motor. 12 is a driven pulley mounted at the lower end of one of the shafts. The driver and driven pulleys are interconnected by a belt 13. 14 and 15 are spur gears mounted at the lower ends of the shafts of the wiper assemblies and in mesh with each other. The upper ends of the slotted pins are provided with open slots and scrapers (not shown) are fitted in the open slots. The scrapers are generally made of rubber. However, the scrapers also can be made of any other flexible material. During operation of the wiping unit, the scrapers at the upper ends of the slotted pins of the wiper assemblies are engaged in the closing ends of the coated tube.

The dimensions of the scrapers are selected to maintain close tolerances with the inner surface of the closing ends of the coated tube. During operation of the wiping unit, the slotted pins rotate in opposite directions and the scrapers at the upper ends of the slotted pins engaged in the closing ends of the coated tube swipe down and remove the powder coating at the inner surfaces of the closing ends of the coated tube.
According to the invention the slotted pins and the respective shafts of the wiper assemblies are in thread engagement in a direction opposite to the directions of rotation of the wiper assemblies. Therefore, a tight fit between the slotted pins and the shafts are maintained during rotation of the wiper assemblies. As a result, loosening of the slotted pins and the shafts is avoided so also play and friction between the slotted pins and shafts. This ensures smooth and trouble free rotation of the wiper assemblies for a long period of time so as to achieve proper cleaning of the inside of the closing ends of the coated tubes. Wear and tear to the slotted pins and the shafts are avoided and their maintenance is reduced and life is increased. The invention eliminates the grub screws and ensures a tight fit between the slotted pins and the shafts so as to reduce the maintenance cost and ensure a smooth and trouble free operation of the wiper assemblies for a long period of time. Down time is reduced, cost is reduced and productivity is increased. Further the cylindrical portion of the bushes increases the height of the joint between the flared portions of the slotted pins and the bushes. As a result, the powder being scraped down and getting accumulated on the base plate does not easily enter the clearance between the flared portion of the slotted pins and the bushes and frequency of removal of the powder getting accumulated on the base plate is reduced and downtime is further reduced. Chances of jamming of the slotted pins on the bushes are reduced and damage to the drive arrangement of the wiping unit is eliminated. This further increases

the life of the wiping unit and productivity besides rendering the operation of the wiping unit easy and convenient. The construction of the wiping unit is also simplified.

We claim:
1. A wiping unit for wiping the closing ends of the coated tube of a compact fluorescent lamp, the wiping unit comprising a pair of wiper assemblies disposed vertically in a spaced apart relationship corresponding to the spacing between the closing ends of the coated tube held above the wiper assemblies, the wiper assemblies being disposed for contra rotation about a vertical axis, each of the wiper assemblies comprising a slotted pin having a flared portion at the lower end thereof and rotatably disposed over a bush mounted on a base plate which in turn is mounted on the frame of the wiping unit, a shaft extending into the slotted pin through the base plate, frame and bush, the lower ends of the shafts of the wiper assemblies being coupled to a drive arrangement for rotation of the wiper assemblies in opposite directions, the upper ends of the slotted pins being provided with open slots fitted with scrapers adapted to engaged in the closing ends of the coated tube in close contact therewith, wherein the slotted pin and the shaft of each of the wiper assemblies is coupled together in thread engagement tightened in a direction opposite to the direction of rotation of each of the wiper assemblies and wherein the bush of each of the wiper assemblies comprises a truncated cone shaped portion and cylindrical portion in co-axial relationship.
2. The wiping unit as claimed in claim 1, wherein the truncated cone shaped portion and cylindrical portion of the bush are integrally formed.
3. The wiping unit as claimed in claim 1 or 2, wherein the scrapers are made of rubber.