A Lamp Assembly

Europäisches Patentamt *EP001176363A2* (19) European Patent Office

Office européen des brevets (11) EP 1 176 363 A2

(12) EUROPEAN PATENT APPLICATION

(43) Date of publication: (51) Int Cl.7: F21V 19/00 30.01.2002 Bulletin 2002/05

(21) Application number: 01306081.9

(22) Date of filing: 13.07.2001

(84) Designated Contracting States: (71) Applicant: Thomas & Betts International, Inc. AT BE CH CY DE DK ES FI FR GB GR IE IT LI LU Sparks, Nevada 89434 (US) MC NL PT SE TR Designated Extension States: (72) Inventor: McKenna, John AL LT LV MK RO SI Lidcombe, New South Wales 2141 (AU)

(30) Priority: 14.07.2000 AU PP879200 (74) Representative: Denmark, James Bailey, Walsh & Co. 5 York Place Leeds LS1 2SD Yorkshire (GB)

(54) A lamp assembly

(57) A lamp assembly for providing a safer means cathode fluorescent lamp is placed; and (iii) at least one for handling of cold cathode fluorescent lamps wherein end cap (3). In particular the present invention provides said lamp assembly comprises: (i) a cold cathode fluo- a lamp assembly for use with "EXIT" signage manufac- rescent lamp (1); (ii) a housing (2) into which said cold tured in accordance with recognised international codes or standards. EP 1 176 363 A2

Printed by Jouve, 75001 PARIS (FR) 1 EP 1 176 363 A2 2

Description (i) a Cold Cathode fluorescent lamp; (ii) a housing into which the Cold Cathode fluores- [0001] The present invention relates to a lamp assem- cent lamp is placed; and bly and in particular to Cold Cathode fluorescent lamps (iii) an end cap or caps. and their use in a lamp assembly. The lamp assembly 5 of the present invention provides a safer means for han- [0009] The end caps seal the housing and provide for dling of Cold Cathode fluorescent lamps. a means of connection of the lamp to the control gear. [0002] Cold Cathode fluorescent lamps have been [0010] The Cold Cathode fluorescent lamp is most available for many years. Neon signs are one example preferably of a substantially elongated tubular configu- of the early implementation of Cold Cathode fluorescent 10 ration having a diameter of 1.8 mm to 6 mm. Most pref- lamps. Smaller diameter Cold Cathode fluorescent erably the Cold Cathode fluorescent lamp is 2 to 3 mm lamps, down to 2.5 mm diameter, have been developed in diameter. to provide a light source, for example as back lighting [0011] The housing is most preferably glass tubing, for laptop computers, document scanners, photocopiers but may also be tubing of a suitable plastic material, and and the like. 15 is also of a substantially elongated tubular configuration. [0003] Cold Cathode fluorescent lamps have a single The housing should be of sufficient diameter to house connection at each end and generally do not require the Cold Cathode fluorescent lamp comfortably within heating above ambient temperature to produce light. the housing. Preferably, the housing may have a diam- Cold Cathode fluorescent lamps may be custom made eter of from 5 mm to 38 mm, and most preferably about and can be contoured to almost any shape. Although 20 6 to 10 mm in diameter. widely used, the use of Cold Cathode fluorescent lamps [0012] Generally, the diameter of the housing may be has been restricted in its usage due largely to difficulties of such a diameter as to conform with standard lamp in handling smaller diameter lamps. For example, in EX- classification. For example, the housing may have a T2 IT signage, use of Cold Cathode fluorescent lamps is classification which indicates a diameter of two eighths generally limited to edge lit diffuser panels in much the 25 of an inch. A T5 classification indicates the diameter is same way as laptops, although a 6 mm diameter Cold five eighths of an inch, and so on. The housing may con- Cathode fluorescent lamp held in place with clips has form to any standard size in accordance with standard been used in a "back lit" EXIT sign. In this case, the lamp classification. has semi-exposed end connections. [0013] The end cap or caps may be made of any [0004] The difficulty with utilising Cold Cathode fluo- 30 standard material such as moulded plastic. Most pref- rescent lamps in a medium such as an EXIT sign is that erably it is made of a one piece moulded plastic. difficulties may exist with respect to safety, lamp han- [0014] The end caps provide a means of holding the dling and replacement. An EXIT sign utilizing a Cold Cold Cathode fluorescent lamp within the housing and Cathode fluorescent lamp would usually operate the to provide a connection interface for the lamp with a lamp on approximately 600 volts AC therefore, safety 35 lamp holder. and handling difficulties arise due to the semi-exposed [0015] The Cold Cathode fluorescent lamp generally lamp end connection, and the potential to break smaller fits into the end caps via a recess in each end cap that diameter lamps. is tailored with respect to the Cold Cathode fluorescent [0005] For an EXIT sign, the relative dimensions, in- lamp diameter. This recess is preferably in the form of cluding size and spacing for each letter, size of the sign, 40 four diametrically opposed longitudinal finger sections colour and intensity of the light including the intensity of that support the Cold Cathode fluorescent lamp concen- each of the letters, and the ratio of intensity between the trically within each end cap. The housing of the lamp illumination of each letter as opposed to the illumination assembly is also supported, preferably concentrically of the background is generally regulated. In Australia with each end cap by this finger detail. A Ultra Violet and New Zealand the applicable standard is regulated 45 cure acrylic glue is preferably used and introduced via by Australian/New Zealand standard AS/NZS 2293. a filling hole in the end cap which provides the securing [0006] The discussion of the background to the inven- mechanism between the end cap and the housing. The tion herein is included to explain the context of the in- Cold Cathode fluorescent lamp is free to move within vention. This is not to be taken as an admission that any the constraints of the finger recesses to allow for expan- of the material referred to was published, known or part 50 sion/contraction of the lamp assembly during operation of the common general knowledge in Australia as at the and to provide further shock protection during handling priority date of this application. and transport. The connection wire from each end of the [0007] It is a desirable feature of the present invention Cold Cathode fluorescent lamp is fed through a hole in to provide a Cold Cathode fluorescent lamp that over- the end of the end cap during this assembly process, comes one or more of the difficulties associated with the 55 and is formed back along the end cap towards the centre prior art. of the lamp assembly into a recess in the end cap, where [0008] The present invention relates to a lamp assem- it is then heat staked to the end cap. bly including: [0016] A further embodiment is to assemble the Cold

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Cathode fluorescent lamp into housing of different diam- application. eter from 4mm diameter up to and including a T12 [0024] The purpose of the diffusive variant is to (38mm) style, utilising either a standard type single or achieve a more dispersed light source in its simplest two pin fluorescent end caps, or purpose designed end form, and to provide a radially gradiated intensity from caps. 5 the lamp assembly in its most complex form. This has [0017] Generally, the length of the lamp and the hous- application in reducing the centre luminance of the dif- ing is such to enable the lamp to fit within an EXIT sign fuser panel that carries the signage information when in accordance with the applicable code or standard. this panel is in close proximity to the lamp assembly. Cold Cathode lamps in accordance with this invention This is important particularly in regard to EXIT signage are suitable for mounting either as a "back lit" light 10 where the ratio of the background luminance across the source for an EXIT sign, or as an "edge lit" light source face of the sign has to meet relevant standards, and having a diffuser panel to transmit the light source within would allow for EXIT signs to be reduced in depth. the EXIT sign. [0025] A further extension of the present invention in- [0018] Preferably, the effective light length of the lamp volves the mounting of a cold cathode fluorescent lamp assembly is from 80 to 380mm, most preferably 297 15 (s) within an assembly that will connect to either com- mm. The overall length of the lamp assembly including mercially available or purpose built lamphoiders, but dif- end caps is 126 to 426 mm, most preferably 343 mm. fers in that there is electronic control gear also fitted [0019] The lamp assembly preferably fits within an within the assembly that allows the assembly to operate Exit Sign by engaging into lampholders that are usually "stand alone" from either normal mains voltage, or from attached to the housing or other part that attaches to the 20 a mains derived voltage that would be available at the housing of the Exit Sign. In a preferred embodiment, the lamp holder connections of an existing luminaire. Lamp Assembly engages into a commercially available [0026] The purpose of this extension is to provide a lampholder that is designed to accommodate a "T2" replacement lamp for the mains operated lamp in sus- style conventional fluorescent lamp. These lampholders tained EXIT signs (sustained EXIT signs have two inde- affix to a purpose designed "lampholder adapter". This 25 pendent lamps - one that is illuminated during normal lampholder adapter then affixes to the frame of the Exit mains operation, and one that is illuminated during pow- Sign. The use of these lampholder adapters is that the er loss). This allows the benefits of the long lamp life Exit Sign may be fitted with either the Cold Cathode flu- exhibited by the cold cathode fluorescent lamp to be orescent lamp assembly of the present invention, or with adapted to existing EXIT signage without the need for a conventional 10W T8 fluorescent lamp with lamphold- 30 any modifications to the existing sign. Similar principles er adapters that accept Standard T8 lampholders. of construction would apply, with several implementa- [0020] By placing the Cold Cathode fluorescent lamp tions available to achieve the desired configuration. within a housing such as a glass tube and affixing the [0027] The present invention enables a Cold Cathode end caps, the lamp may be handled with a greater de- fluorescent lamp to be used safely in a back lit or edge gree of safety than Cold Cathode lamps that are cur- 35 lit EXIT sign having regard to the potential safety con- rently available. cerns, such as physical injury from breakage or electric [0021] For a Cold Cathode fluorescent lamp to shock. The Cold Cathode fluorescent lamp assembly of achieve optimum luminous efficacy, it should be operat- the present invention may be readily replaced, handled, ed in an ambient temperature of about 40-45°C. By sur- shipped and stored while providing an optimal operating rounding the Cold Cathode lamp with a housing, the en- 40 environment for the Cold Cathode fluorescent lamp. closure provides for an elevation in temperature to nor- [0028] The lamp assembly in accordance with this in- mal operating conditions. At 40 - 45°C, there is a greater vention may be used for any application, and in partic- luminous efficacy for a Cold Cathode fluorescent lamp ular, where a lamp having a small diameter is desirable. of around 8-10% above output rated at 25°C. At approx- A lamp assembly of smaller diameter allows for an EXIT imately 55°C the efficacy returns to the nominal point 45 Sign to be reduced in depth whilst maintaining the var- and decreases with increasing temperature. iations of luminance across the face of the EXIT Sign [0022] Either reflective or diffusive material may be within the tolerance allowed by the applicable code or applied to the lamp housing, or the manufacture of the standard. cold cathode fluorescent lamp altered to achieve these [0029] The present invention will now be described reflective/diffusive properties. 50 with reference to the accompanying drawings. These [0023] The purpose of the reflective variant is to drawings are merely provided to illustrate preferred em- achieve an integral reflector along the length of the lamp bodiments of the present invention, and the invention assembly to enable the light emmitted from the lamp as- should not be considered to be limited thereto. sembly to be concentrated and/or directed in a particular [0030] Figure 1 illustrates a Cold Cathode lamp (1) direction. This has particular application for edge light- 55 within a glass housing (2). End caps (3) are provided at ing a light diffusing panel that can be used as the basis each end of the glass housing. Wire (4) is heat sealed for signage including EXIT Signage. The width of the into a slot within the end cap at both ends of the Cold longitudinal clear area can be varied depending on the Cathode lamp to provide an electrical connection while

3 5 EP 1 176 363 A2 6 ensuring that the connection is not exposed. The end 8. A lamp assembly according to claim 7 wherein said caps also hold the lamp away from the housing. finger sections also engage with the housing to sup- [0031] Figure 2 illustrates a Cold Cathode lamp of the port said housing substantially concentrically within invention fitted within an EXIT sign. The Cold Cathode each end cap. fluorescent lamp (1) and glass housing (2) is shown in 5 a position fitted with end caps (3) in holders (6) in a "back 9. A lamp assembly according to claim 8 wherein a lit" EXIT sign. securing means fixes the housing into position with- [0032] Throughout the description and claims of the in the end cap/s. specification the word "comprise" and variations of the word, such as "comprising" and "comprises", is not in- 10 10. A lamp assembly according to claim 9 wherein the tended to exclude other additives, components, integers securing means is an acrylic glue introduce via a or steps. hole in each end cap. [0033] It is to be understood that the embodiments described within the specification are merely preferable, 11. A lamp assembly according to claim 10 wherein the and that alterations and amendments without departing 15 acrylic glue is an ultra violet cure acrylic glue. from the spirit of the invention described herein should also be considered as part of the invention. 12. A lamp assembly according to any one of the pre- ceding claims wherein said cold cathode fluorescent lamp is of a substantially elongated tubular Claims 20 configuration having a diameter of 1.8 mm to 6.0 mm . 1. A lamp assembly wherein said lamp assembly comprises: 13. A lamp assembly according to claim 12 wherein said cold cathode fluorescent lamp has a diameter (i) a cold cathode fluorescent lamp; 25 of 2 to 3 mm. (ii) a housing into which said cold cathode fluorescent lamp is placed; and 14. A lamp assembly according to any one of the pre- (iii) at least one end cap. ceding claims wherein the housing is of a substan- tial elongated tubular configuration of sufficient di- 2. A lamp assembly according to claim 1 wherein said 30 ameter to comfortably house the cold cathode fluo- lamp assembly has two end caps. rescent lamp.

3. A lamp assembly according to claim 1 or claim 2 15. A lamp assembly according to claim 14 wherein the wherein said end cap/s seal the housing and pro- housing is tubing made of glass or suitable plastic vide a means of connection of the fluorescent lamp 35 material. to a controlling means. 16. A lamp assembly according to any one of the pre- 4. A lamp assembly according to any one of the pre- ceding claims where the housing has a diameter of ceding claims wherein each of said end cap/s is from 5mm to 38mm. made of a one piece moulded plastic. 40 17. A lamp assembly according to claim 16 wherein the 5. A lamp assembly according to any one of the pre- housing has a diameter from 6mm to 10mm ceding claims wherein said end cap/s provide a means of holding the cold cathode fluorescent lamp 18. A lamp assembly according to any one of the pre- within the housing and provide a connection inter- 45 ceding claims wherein said end cap/s comprise a face for the lamp with a lamp holder. standard type single or two pin fluorescent end cap.

6. A lamp assembly according to any one of the pre- 19. A lamp assembly according to any one of the pre- ceding claims wherein the cold cathode fluorescent ceding claims wherein reflective or diffusive mate- lamp engages with the end cap/s via a recess in 50 rial is incorporated in or applied to the lamp assem- each end cap which is tailored with respect to the bly. cold cathode fluorescent lamp diameter. 20. A lamp assembly according to any one of the pre- 7. A lamp assembly according to claim 6 wherein the ceding claims wherein said lamp assembly further recess is in the form of four diametrically opposed 55 provides electronic control gear to enable the lamp finger sections which support the cold cathode flu- assembly to operate from a normal mains power orescent lamp substantially concentrically within source, or from a mains derived power source. each end cap.

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21. A lamp assembly according to any one of the pre- ceding claims dimensioned to fit within standard EXIT signs in accordance with commonly used international standards. 5 22. A lamp assembly according to claim 21 wherein said lamp assembly is dimensioned to fit within an EXIT sign in accordance with AS/NZS 2293.

23. A lamp assembly according to claim 20 or claim 21 10 wherein the lamp assembly is held in position within said EXIT sign by one or more lampholders attached to or connected to the housing of the EXIT sign. 15 24. A lamp assembly according to any one of the pre- ceding claims substantially as hereinbefore described with reference to any of the figures.

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