GB2209431A

GB2209431A - A discharge lamp provided with a removable ballast unit

Info

Publication number: GB2209431A
Application number: GB8720622A
Authority: GB
Inventors: Man-Chung Cha
Original assignee: FOOK TIN PLASTIC FACTORY LIMIT; Fook Tin Plastic Factory Ltd
Current assignee: FOOK TIN PLASTIC FACTORY LIMIT; Fook Tin Plastic Factory Ltd
Priority date: 1987-09-02
Filing date: 1987-09-02
Publication date: 1989-05-10
Also published as: GB8720622D0

Abstract

An electric discharge lamp comprises a lamp unit (2) housing a folded fluorescent tube (4) and a starter (23), and a separable ballast unit (1) on which the lamp unit (2) is removably mounted in electrical connection therewith. The ballast unit (1) carries a screw threaded or bayonet connector (18) for electrical connection to a light bulb socket. <IMAGE>

Description

ELECTRIC DISCHARGE LAMP The present invention relates to an electric discharge lamp.

Various types of so-called compact size electric discharge lamps are known and generally comprise a folded or bent fluorescent tube within a housing and associated electrical components such as a ballast and starter. Although the lamp may have a comparatively long life, it will eventually need replacement. This is almost always due to failure of the tube or possibly the starter since the ballast is unlikely to fail. Nevertheless, the complete lamp must be replaced and the presence of the ballast in the replacement lamp contributes significantly to the cost thereof.

According to the present invention there is provided an electric discharge lamp comprising a lamp unit with a discharge tube, and a separate ballast unit on which the lamp unit is removably mounted in electrical connection therewith, said ballast unit being provided with means for connecting the lamp to a light bulb socket.

Since the lamp unit is removably mounted on the ballast unit, it is only necessary to replace the lamp unit (without the comparatively expensive ballast) when the tube fails. Preferably the lamp unit is also provided with the starter for the lamp so that should the starter fail then, once again, it is only necessary to replace the lamp unit.

Preferably also the lamp unit and the ballast unit are provided with complementary connection means which provide both for the removable mounting of the lamp unit on the ballast unit and one electrical connection therebetween.

The invention also provides a lamp unit without a ballast for an electric discharge lamp, comprising a discharge tube mounted in a housing, a starter mounted across the electrodes of the discharge tube, a screw threaded electrically conducting component on the base of the housing for removably mounting the lamp unit on a ballast unit and for providing one electrical connection therewith, and a terminal for providing the other electrical connection to said ballast unit.

The invention additionally provides a ballast for connection to a lamp unit as defined in the preceding paragraph comprising a body within which the ballast is located, means for connecting the ballast unit to a power source, a screw threaded electrically conducting component complementary to that of the lamp unit, and a second terminal for electrical connection with said first terminal of the lamp unit.

The invention will be further described by way of example only with reference to the accompanying drawing which is an exploded perspective view of one embodiment of discharge lamp in accordance with the invention.

The illustrated discharge lamp comprises a ballast unit 1 and a lamp unit 2 itself comprising a light transparent housing 3, a folded fluorescent tube 4 mounted on a support plate 5, and a base 6. The ends of tube 4 locate through respective apertures 7 in plate 5 and the tube is supported on the plate by a bracket 8 which holds the tube against lug 9 provided integral with plate 5. Plate 5 has an integral collar 10 with circumferentially spaced notches 11 and a radial flange 12. Tabs 13 are provided on housing 3 and, for assembly of the housing onto the plate 5, slide into the notches 11 such that the lower edge of housing 3 abuts against flange 12.

A conventional starter 23 is electrically connected across the electrodes of tube 4.

Base 6 comprises a cylindrical collar 6a, a circular wall 6b of a smaller diameter, and a frusto-conical wall 6c connecting the collar 6a and the wall 6b. A cylindrical recess 14 is provided on the wall 6b opposite tube 4. Within recess 14 is a screw threaded male electrical connector 15 encircling a conducting button 16 biassed outwardly of recess 14.

Connector 15 and button 16 are connected by respective wires 17 to the electrodes of tube 4.

Eight equi-angularly spaced ventilation slots 24 are provided in the wall 6c of the base 6.

Ballast unit 1 houses a conventional ballast 22 and has a standard screw threaded electrical connecting unit 18 for mounting the ballast unit in a conventional screw-threaded light socket. On the front face of ballast unit 1 is an upstanding plastics collar 19 of a diameter just less than that of cylindrical recess 14. Collar 19 encircles a female screw threaded connector 20 in which the male connector 15 will engage. A terminal 21 is provided centrally within female connector 20. This connector 20 and the terminal 21 are electrically connected to the unit 18 via the ballast in conventional manner.

To use the illustrated discharge lamp, the ballast unit 1 and lamp unit 2 are assembled by screw threaded engagement of connector 15 in connector 20.

This causes button 16 to contact terminal 21 and a good electrical connection is assured by the outward biassing of the button. The assembled lamp may now be screwed into a light socket for normal operation.

If either the tube 4 or the starter 13 should fail, then it is only necessary to replace the light unit 2 so that the expense of the ballast is not incurred.

Various modifications may be made to the described embodiment. For example, the screw connector 18 may be replaced by a bayonet type fitting for a light socket.

Claims

1. An electric discharge lamp comprising a lamp unit with a discharge tube and a separate ballast unit on which the lamp unit is removably mounted in electrical connection therewith, said ballast unit being provided with means for readily removably connecting the lamp to a light bulb socket.

2. A lamp as claimed in claim 1 having a starter provided in the lamp unit.

3. A lamp as claimed in claim 1 or 2, wherein the lamp unit and the ballast unit are provided with complementary connection means which provide both for the removable mounting of the lamp unit on the ballast unit and one electrical connection therebetween.

4. A lamp as claimed in claim 3, wherein the complementary connection means comprise screw-threaded components on the lamp unit and the base unit.

5. A lamp as claimed in claim 4, wherein the screw threaded components comprise male and female parts on the respective units.

6. A lamp as claimed in claim 5, wherein the screw male part encircles a first terminal on the respective unit, and the female part encircles a second terminal on the other respective unit, said first and second terminals being in contact to provide the other electrical connection between the lamp unit and the ballast unit.

7. A lamp as claimed in claim 6, wherein the first terminal is a button biassed towards the other respective unit.

8. A lamp as claimed in claim 5 or 6, wherein said male part is located in a recess in a base of the lamp unit and said female part is provided as a projection on said ballast unit.

9. A lamp as claimed in any one of the preceding claims, wherein ventilation slots are provided in a base of the lamp unit.

10. A lamp unit without a ballast for an electric discharge lamp comprising a discharge tube mounted in a housing, a starter mounted across electrodes of the discharge tube, mounting means on the base of the housing for removably mounting the lamp unit on a ballast unit and for providing one electrical connection therewith, and a terminal for providing the other electrical connection to said ballast unit.

11. A lamp unit as claimed in claim 10, wherein the mounting means is a screw threaded male component, and said terminal is a button encircled by the male component and biassed outwardly of the housing.

12. A lamp unit as claimed in claim 11, wherein the screw threaded component is located in a recess in the base of the housing.

13. A ballast unit for connection to a lamp unit as claimed in claim 10 comprising a body within which the ballast is located, means for connecting the ballast unit to a light bulb socket, mounting means complementary to that of the lamp unit, and a terminal for electrical connection with said terminal of the lamp unit.

14. A ballast unit as claimed in claim 13, wherein the mounting means is a female component, and the terminal is encircled by the mounting means.

15. A ballast unit as claimed in claim 14, wherein the mounting means is provided as a projection on the ballast unit.

16. An electric discharge lamp comprising a lamp unit having a discharge tube and a starter, and a ballast unit on which the lamp unit is removably mounted in electrical connection therewith, said ballast unit being provided with means for connecting the lamp to a power source.

17. An electric discharge lamp substantially as hereinbefore described with reference to the accompanying drawing.

18. A lamp unit without a ballast substantially as hereinbefore described with reference to the accompanying drawing.

19. A ballast unit substantially as hereinbefore described with reference to the accompanying drawing.